title: Xenotransplantation

text: Binding of the previously mentioned XNAs to the donor endothelium leads to the activation of host macrophages as well as the endothelium itself. The endothelium activation is considered type II since gene induction and protein synthesis are involved. The binding of XNAs ultimately leads to the development of a procoagulant state, the secretion of inflammatory cytokines and chemokines, as well as expression of leukocyte adhesion molecules such as E-selectin, intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1).


title: Xenotransplantation

text: This response is further perpetuated as normally binding between regulatory proteins and their ligands aid in the control of coagulation and inflammatory responses. However, due to molecular incompatibilities between the molecules of the donor species and recipient (such as porcine major histocompatibility complex molecules and human natural killer cells), this may not occur.


title: Xenotransplantation

text: Due to its complexity, the use of immunosuppressive drugs along with a wide array of approaches are necessary to prevent acute vascular rejection, and include administering a synthetic thrombin inhibitor to modulate thrombogenesis, depletion of anti-galactose antibodies (XNAs) by techniques such as immunoadsorption, to prevent endothelial cell activation, and inhibiting activation of macrophages (stimulated by CD4 T cells) and NK cells (stimulated by the release of Il-2). Thus, the role of MHC molecules and T cell responses in activation would have to be reassessed for each species combo.


title: Xenotransplantation

text: If hyperacute and acute vascular rejection are avoided accommodation is possible, which is the survival of the xenograft despite the presence of circulating XNAs. The graft is given a break from humoral rejection when the complement cascade is interrupted, circulating antibodies are removed, or their function is changed, or there is a change in the expression of surface antigens on the graft. This allows the xenograft to up-regulate and express protective genes, which aid in resistance to injury, such as heme oxygenase-1 (an enzyme that catalyzes the degradation of heme).


title: Xenotransplantation

text: Rejection of the xenograft in hyperacute and acute vascular rejection is due to the response of the humoral immune system, since the response is elicited by the XNAs. Cellular rejection is based on cellular immunity, and is mediated by natural killer cells that accumulate in and damage the xenograft and T-lymphocytes which are activated by MHC molecules through both direct and indirect xenorecognition.


title: Xenotransplantation

text: In direct xenorecognition, antigen presenting cells from the xenograft present peptides to recipient CD4 T cells via xenogeneic MHC class II molecules, resulting in the production of interleukin 2 (IL-2). Indirect xenorecognition involves the presentation of antigens from the xenograft by recipient antigen presenting cells to CD4 T cells. Antigens of phagocytosed graft cells can also be presented by the host's class I MHC molecules to CD8 T cells.


title: Xenotransplantation

text: The strength of cellular rejection in xenografts remains uncertain, however, it is expected to be stronger than in allografts due to differences in peptides among different animals. This leads to more antigens potentially recognized as foreign, thus eliciting a greater indirect xenogenic response.


title: Xenotransplantation

text: A proposed strategy to avoid cellular rejection is to induce donor non-responsiveness using hematopoietic chimerism. Donor stem cells are introduced into the bone marrow of the recipient, where they coexist with the recipient's stem cells. The bone marrow stem cells give rise to cells of all hematopoietic lineages, through the process of hematopoiesis. Lymphoid progenitor cells are created by this process and move to the thymus where negative selection eliminates T cells found to be reactive to self. The existence of donor stem cells in the recipient's bone marrow causes donor reactive T cells to be considered self and undergo apoptosis.


title: Xenotransplantation

text: Chronic rejection is slow and progressive, and usually occurs in transplants that survive the initial rejection phases. Scientists are still unclear how chronic rejection exactly works, research in this area is difficult since xenografts rarely survive past the initial acute rejection phases. Nonetheless, it is known that XNAs and the complement system are not primarily involved. Fibrosis in the xenograft occurs as a result of immune reactions, cytokines (which stimulate fibroblasts), or healing (following cellular necrosis in acute rejection). Perhaps the major cause of chronic rejection is arteriosclerosis. Lymphocytes, which were previously activated by antigens in the vessel wall of the graft, activate macrophages to secrete smooth muscle growth factors. This results in a build up of smooth muscle cells on the vessel walls, causing the hardening and narrowing of vessels within the graft. Chronic rejection leads to pathologic changes of the organ, and is why transplants must be replaced after so many years. It is also anticipated that chronic rejection will be more aggressive in xenotransplants as opposed to allotransplants.


title: Xenotransplantation

text: Successful efforts have been made to create knockout mice without α1,3GT; the resulting reduction in the highly immunogenic αGal epitope has resulted in the reduction of the occurrence of hyperacute rejection, but has not eliminated other barriers to xenotransplantation such as dysregulated coagulation, also known as coagulopathy.


title: Xenotransplantation

text: Different organ xenotransplants result in different responses in clotting. For example, kidney transplants result in a higher degree of coagulopathy, or impaired clotting, than cardiac transplants, whereas liver xenografts result in severe thrombocytopenia, causing recipient death within a few days due to bleeding. An alternate clotting disorder, thrombosis, may be initiated by preexisting antibodies that affect the protein C anticoagulant system. Due to this effect, porcine donors must be extensively screened before transplantation. Studies have also shown that some porcine transplant cells are able to induce human tissue factor expression, thus stimulating platelet and monocyte aggregation around the xenotransplanted organ, causing severe clotting. Additionally, spontaneous platelet accumulation may be caused by contact with pig von Willebrand factor.


title: Xenotransplantation

text: Just as the α1,3G epitope is a major problem in xenotransplantation, so too is dysregulated coagulation a cause of concern. Transgenic pigs that can control for variable coagulant activity based on the specific organ transplanted would make xenotransplantation a more readily available solution for the 70,000 patients per year who do not receive a human donation of the organ or tissue they need.


title: Xenotransplantation

text: Extensive research is required to determine whether animal organs can replace the physiological functions of human organs. Many issues include size – differences in organ size limit the range of potential recipients of xenotransplants; longevity – The lifespan of most pigs is roughly 15 years, currently it is unknown whether or not a xenograft may be able to last longer than that; hormone and protein differences – some proteins will be molecularly incompatible, which could cause malfunction of important regulatory processes. These differences also make the prospect of hepatic xenotransplantation less promising, since the liver plays an important role in the production of so many proteins;


title: Xenotransplantation

text: environment – for example, pig hearts work in a different anatomical site and under different hydrostatic pressure than in humans;


title: Xenotransplantation

text: temperature – the body temperature of pigs is 39 °C (2 °C above the average human body temperature). Implications of this difference, if any, on the activity of important enzymes are currently unknown.


title: Xenotransplantation

text: Xenozoonosis, also known as zoonosis or xenosis, is the transmission of infectious agents between species via xenograft. Animal to human infection is normally rare, but has occurred in the past. An example of such is the avian influenza, when an influenza A virus was passed from birds to humans. Xenotransplantation may increase the chance of disease transmission for 3 reasons: (1) implantation breaches the physical barrier that normally helps to prevent disease transmission, (2) the recipient of the transplant will be severely immunosuppressed, and (3) human complement regulators (CD46, CD55, and CD59) expressed in transgenic pigs have been shown to serve as virus receptors, and may also help to protect viruses from attack by the complement system.


title: Xenotransplantation

text: Examples of viruses carried by pigs include porcine herpesvirus, rotavirus, parvovirus, and circovirus. Porcine herpesviruses and rotaviruses can be eliminated from the donor pool by screening, however others (such as parvovirus and circovirus) may contaminate food and footwear then re-infect the herd. Thus, pigs to be used as organ donors must be housed under strict regulations and screened regularly for microbes and pathogens. Unknown viruses, as well as those not harmful in the animal, may also pose risks. Of particular concern are PERVS (porcine endogenous retroviruses), vertically transmitted microbes that embed in swine genomes. The risks with xenosis are twofold, as not only could the individual become infected, but a novel infection could initiate an epidemic in the human population. Because of this risk, the FDA has suggested any recipients of xenotransplants shall be closely monitored for the remainder of their life, and quarantined if they show signs of xenosis.


title: Xenotransplantation

text: Baboons and pigs carry myriad transmittable agents that are harmless in their natural host, but extremely toxic and deadly in humans. HIV is an example of a disease believed to have jumped from monkeys to humans. Researchers also do not know if an outbreak of infectious diseases could occur and if they could contain the outbreak even though they have measures for control. Another obstacle facing xenotransplants is that of the body's rejection of foreign objects by its immune system. These antigens (foreign objects) are often treated with powerful immunosuppressive drugs that could, in turn, make the patient vulnerable to other infections and actually aid the disease. This is the reason the organs would have to be altered to fit the patients' DNA (histocompatibility).


title: Xenotransplantation

text: In 2005, the Australian National Health and Medical Research Council (NHMRC) declared an eighteen-year moratorium on all animal-to-human transplantation, concluding that the risks of transmission of animal viruses to patients and the wider community had not been resolved.


title: Xenotransplantation

text: This was repealed in 2009 after an NHMRC review stated "... the risks, if appropriately regulated, are minimal and acceptable given the potential benefits.", citing international developments on the management and regulation of xenotransplantation by the World Health Organisation and the European Medicines Agency.


title: Xenotransplantation

text: Endogenous retroviruses are remnants of ancient viral infections, found in the genomes of most, if not all, mammalian species. Integrated into the chromosomal DNA, they are vertically transferred through inheritance. Due to the many deletions and mutations they accumulate over time, they usually are not infectious in the host species, however the virus may become infectious in another species. PERVS were originally discovered as retrovirus particles released from cultured porcine kidney cells. Most breeds of swine harbor approximately 50 PERV genomes in their DNA. Although it is likely that most of these are defective, some may be able to produce infectious viruses so every proviral genome must be sequenced to identify which ones pose a threat. In addition, through complementation and genetic recombination, two defective PERV genomes could give rise to an infectious virus. There are three subgroups of infectious PERVs (PERV-A, PERV-B, and PERV-C). Experiments have shown that PERV-A and PERV-B can infect human cells in culture. To date no experimental xenotransplantations have demonstrated PERV transmission, yet this does not mean PERV infections in humans are impossible. Pig cells have been engineered to inactivate all 62 PERVs in the genome using CRISPR Cas9 genome editing technology, and eliminated infection from the pig to human cells in culture.


title: Xenotransplantation

text: Xenografts have been a controversial procedure since they were first attempted. Many, including animal rights groups, strongly oppose killing animals to harvest their organs for human use. In the 1960s, many organs came from the chimpanzees, and were transferred into people that were deathly ill, and in turn, did not live much longer afterwards. Modern scientific supporters of xenotransplantation argue that the potential benefits to society outweigh the risks, making pursuing xenotransplantation the moral choice. None of the major religions object to the use of genetically modified pig organs for life-saving transplantation. Religions such as Buddhism and Jainism, however, have long espoused non-violence towards all living creatures.


title: Xenotransplantation

text: In general, the use of pig and cow tissue in humans has been met with little resistance, save some religious beliefs and a few philosophical objections. Experimentation without consent doctrines are now followed, which was not the case in the past, which may lead to new religious guidelines to further medical research on pronounced ecumenical guidelines. The "Common Rule" is the United States bio-ethics mandate .


title: Xenotransplantation

text: At the beginning of the 20th century when studies in xenotransplantation were just beginning, few questioned the morality of it, turning to animals as a "natural" alternative to allografts. While satirical plays mocked xenografters such as Serge Voronoff, and some images showing emotionally distraught primates appeared - who Voronoff had deprived of their testicles - no serious attempts were yet made to question the science based on animal rights concerns. Xenotransplantation was not taken seriously, at least in France, during the first half of the 20th century.


title: Xenotransplantation

text: With the Baby Fae incident of 1984 as the impetus, animal rights activists began to protest, gathering media attention and proving that some people felt that it was unethical and a violation of the animal's own rights to use its organs to preserve a sick human's life. Treating animals as mere tools for the slaughter on demand by human will would lead to a world they would not prefer. Supporters of the transplant pushed back, claiming that saving a human life justifies the sacrifice of an animal one. Most animal rights activists found the use of primate organs more reprehensible than those of, for example, pigs. As Peter Singer et al. have expressed, many primates exhibit greater social structure, communication skills, and affection than mentally deficient humans and human infants. Despite this, it is considerably unlikely that animal suffering will provide sufficient impetus for regulators to prevent xenotransplantation.


title: Xenotransplantation

text: Autonomy and informed consent are important when considering the future uses of xenotransplantation. A patient undergoing xenotransplantation should be fully aware of the procedure and should have no outside force influencing their choice. The patient should understand the risks and benefits of such a transplantation. However, it has been suggested that friends and family members should also give consent, because the repercussions of transplantation are high, with the potential of diseases and viruses crossing over to humans from the transplantation. Close contacts are at risk for such infections. Monitoring of close relations may also be required to ensure that xenozoonosis is not occurring. The question then becomes: does the autonomy of the patient become limited based on the willingness or unwillingness of friends and family to give consent, and are the principles of confidentiality broken?


title: Xenotransplantation

text: The safety of public health is a factor to be considered. If there is any risk to the public at all for an outbreak from transplantation there must be procedures in place to protect the public. Not only does the recipient of the transplantation have to understand the risks and benefits, but society must also understand and consent to such an agreement.


title: Xenotransplantation

text: The Ethics Committee of the International Xenotransplantation Association points out one major ethical issue is the societal response to such a procedure. The assumption is that the recipient of the transplantation will be asked to undergo lifelong monitoring, which would deny the recipient the ability to terminate the monitoring at any time, which is in direct opposition of the Declaration of Helsinki and the US Code of Federal Regulations.


title: Xenotransplantation

text: In 2007, xenotransplantation was banned under ethical grounds in all countries but Argentina, Russia and New Zealand. Since then, the practice has only been carried out to treatment for diabetes type 1 to serve as a substitute for insulin injections.


title: Xenotransplantation

text: The application of the four bioethics principal is found to be everywhere because it is now standardized in the moral conducts of a laboratory. The four principles emphasize on the informed consent, the Hippocratic Oath to do no harm, apply one's skill to help others, and protecting the rights of others to quality care.


title: Xenotransplantation

text: Problems with xenotransplantation is that even though it has future medical benefits, it also has the serious risk of introducing and spreading the infectious diseases, into the human population.


title: Xenotransplantation

text: There have been guidelines that have been drafted by the government that have the purpose of forming the foundation of infectious disease surveillance. In the United Kingdom, the guideline that were introduced state that first, "the periodic provision of bodily samples that would then be archived for epidemiological purposes;" second, "post-mortem analysis in case of death, the storage of samples post-mortem, and the disclosure of this agreement to their family;" third, "refrain from donating blood, tissue or organs;" fourth, "the use of barrier contraception when engaging in sexual intercourse;" fifth, keep both name and current address on register and to notify the relevant health authorities when moving abroad;" and lastly "divulge confidential information, including one's status as a xenotransplantation recipient to researchers, all health care professionals from whom one seeks professional services, and close contacts such as current and future sexual partners." With these guidelines in place the patient has to abide to these rules until either their lifetime or until the government determines that there is no need for public health safe guards.


title: Xenotransplantation

text: The Food and Drug Administration (FDA) has also stated that if a transplantation takes place the recipient must undergo monitoring for the rest of that recipient's lifetime and waive their right to withdraw. The reason for requiring lifelong monitoring is due to the risk of acute infections that may occur. The FDA suggests that a passive screening program should be implemented and should extend for the life of the recipient.


title: Severin Hacker

text: Severin Hacker (born July 6, 1984) is a Swiss computer scientist who is the co-founder and CTO of Duolingo, the world's most popular language-learning platform.


title: Severin Hacker

text: Hacker was born and raised in Zug and studied at ETH Zurich. In a 2020 interview, Hacker specified that gaming played a large role in his interest in computer science: "What originally drew me to computers was video games and the desire to build your own games and understand how those games are built. I was somewhat obsessed."


title: Severin Hacker

text: He moved to Pittsburgh to study at Carnegie Mellon University where he co-founded Duolingo with Luis von Ahn in 2009.


title: Severin Hacker

text: He received his BS in Computer Science from ETH Zurich in 2006 and his PhD in Computer Science from Carnegie Mellon University in 2014.


title: Severin Hacker

text: Initially, Hacker and his former graduate advisor, Luis von Ahn, wanted to develop an application that could translate internet sites, so that they would be accessible for non-English speakers. They felt that automated translation software wasn't as effective as using the skills and knowledge of bilingual speakers. During Hacker's doctoral studies, Duolingo became a by-product of this idea, or "happy mistake." Hacker's goal for Duolingo was to make it "100% free" so the most disadvantaged person with an internet connection would still have access to it.


title: Severin Hacker

text: Hacker and his team of PhD students used machine learning to personalize Duolingo to each user. Specifically, they wanted to predict what language concepts the user was on the verge of forgetting. In 2012, a study by American universities showed that spending 34 hours of learning on Duolingo was equivalent to a full-semester of a college language course. In 2015, Hacker and von Ahn started selling translations, such as to the Spanish tech news group of CNN.


title: Severin Hacker

text: There are two parts to Hacker's "Retention Philosophy": learning should be fun and motivation should remain high. Through Duolingo, Hacker wants users to have the option to increase their 'stay-tuned quota' which involves adjusting the learning time and difficulty of the course. Another idea derived from Hacker's philosophy was to apply gamification to Duolingo. This was to apply game elements and principles instead of classroom learning tools to the course.


title: Electrolyte imbalance

text: Electrolyte imbalance, or water-electrolyte imbalance, is an abnormality in the concentration of electrolytes in the body. Electrolytes play a vital role in maintaining homeostasis in the body. They help to regulate heart and neurological function, fluid balance, oxygen delivery, acid–base balance and much more. Electrolyte imbalances can develop by consuming too little or too much electrolyte as well as excreting too little or too much electrolyte.


title: Electrolyte imbalance

text: Electrolyte disturbances are involved in many disease processes, and are an important part of patient management in medicine. The causes, severity, treatment, and outcomes of these disturbances can differ greatly depending on the implicated electrolyte. The most serious electrolyte disturbances involve abnormalities in the levels of sodium, potassium or calcium. Other electrolyte imbalances are less common and often occur in conjunction with major electrolyte changes. The kidney is the most important organ in maintaining appropriate fluid and electrolyte balance, but other factors such as hormonal changes and physiological stress play a role.


title: Electrolyte imbalance

text: Calcium, magnesium, potassium, and sodium ions are cations (+), while chloride, and phosphate ions are anions (−).


title: Electrolyte imbalance

text: Chronic laxative abuse or severe diarrhea or vomiting can lead to dehydration and electrolyte imbalance.


title: Electrolyte imbalance

text: People with malnutrition are at especially high risk for an electrolyte imbalance. Severe electrolyte imbalances must be treated carefully as there are risks with overcorrecting too quickly, which can result in arrhythmias, brain herniation, or refeeding syndrome depending on the cause of imbalance.


title: Electrolyte imbalance

text: Electrolytes are important because they are what cells (especially nerve, heart and muscle cells) use to maintain voltages across their cell membranes. Electrolytes have different functions, and an important one is to carry electrical impulses between cells. Kidneys work to keep the electrolyte concentrations in blood constant despite changes in the body. For example, during heavy exercise, electrolytes are lost in sweat, particularly in the form of sodium and potassium. The kidneys can also generate dilute urine to balance sodium levels. These electrolytes must be replaced to keep the electrolyte concentrations of the body fluids constant. Hyponatremia, or low sodium, is the most commonly seen type of electrolyte imbalance.


title: Electrolyte imbalance

text: Treatment of electrolyte imbalance depends on the specific electrolyte involved and whether the levels are too high or too low. The level of aggressiveness of treatment and choice of treatment may change depending on the severity of the disturbance. If the levels of an electrolyte are too low, a common response to electrolyte imbalance may be to prescribe supplementation. However, if the electrolyte involved is sodium, the issue is often water excess rather than sodium deficiency. Supplementation for these people may correct the electrolyte imbalance but at the expense of volume overload. For newborn children, this has serious risks. Because each individual electrolyte affects physiological function differently, they must be considered separately when discussing causes, treatment, and complications.


title: Electrolyte imbalance

text: Though calcium is the most plentiful electrolyte in the body, a large percentage of it is used to form the bones. It is mainly absorbed and excreted through the GI system. The majority of calcium resides extracellularly, and it is crucial for the function of neurons, muscle cells, function of enzymes, and coagulation. The normal range for calcium concentration in the body is 8.5 - 10.5 mg/dL. The parathyroid gland is responsible for sensing changes in calcium concentration and regulating the electrolyte with parathyroid hormone.


title: Electrolyte imbalance

text: Hypercalcemia describes when the concentration of calcium in the blood is too high. This occurs above 10.5 mg/dL.


title: Electrolyte imbalance

text: The most common causes of hypercalcemia are certain types of cancer, hyperparathyroidism, hyperthyroidism, pheochromocytoma, excessive ingestion of vitamin D, sarcoidosis, and tuberculosis. Hyperparathyroidism and malignancy are the predominant causes. It can also be caused by muscle cell breakdown, prolonged immobilization, dehydration.


title: Electrolyte imbalance

text: The predominant symptoms of hypercalcemia are abdominal pain, constipation, kidney stones, extreme thirst, excessive urination, nausea and vomiting. In severe cases where the calcium concentration is >14 mg/dL, individuals may experience confusion, altered mental status, coma, and seizure.


title: Electrolyte imbalance

text: Primary treatment of hypercalcemia consists of administering IV fluids. If the hypercalcemia is severe and/or associated with cancer, it may be treated with bisphosphonates. For very severe cases, hemodialysis may be considered for rapid removal of calcium from the blood.


title: Electrolyte imbalance

text: Hypoparathyroidism and vitamin D deficiency are common causes of hypocalcemia. It can also be caused by malnutrition, blood transfusion, ethylene glycol intoxication, and pancreatitis.


title: Electrolyte imbalance

text: Neurological and cardiovascular symptoms are the most common manifestations of hypocalcemia. Patients may experience muscle cramping or twitching, and numbness around the mouth and fingers. They may also have shortness of breath, low blood pressure, and cardiac arrhythmias.


title: Electrolyte imbalance

text: Patients with hypocalcemia may be treated with either oral or IV calcium. Typically, IV calcium is reserved for patients with severe hypocalcemia. It is also important to check magnesium levels in patients with hypocalcemia and to replace magnesium if it is low.


title: Electrolyte imbalance

text: Chloride, after sodium, is the second most abundant electrolyte in the blood, and most abundant in the extracellular fluid. Most of the chloride in the body is from salt (NaCl) in the diet. Chloride is part of gastric acid (HCl), which plays a role in absorption of electrolytes, activating enzymes, and killing bacteria. The levels of chloride in the blood can help determine if there are underlying metabolic disorders. Generally, chloride has an inverse relationship with bicarbonate, an electrolyte that indicates acid-base status. Overall, treatment of chloride imbalances involve addressing the underlying cause rather than supplementing or avoiding chloride.


title: Electrolyte imbalance

text: Hyperchloremia, or high chloride levels, is usually associated with excess chloride intake (e.g., saltwater drowning), fluid loss (e.g., diarrhea, sweating), and metabolic acidosis.


title: Electrolyte imbalance

text: Patients are usually asymptomatic with mild hyperchloremia. Symptoms associated with hyperchloremia are usually caused by the underlying cause of this electrolyte imbalance.


title: Electrolyte imbalance

text: Hypochloremia, or low chloride levels, are commonly associated with gastrointestinal (e.g., vomiting) and kidney (e.g., diuretics) losses. Greater water or sodium intake relative to chloride also can contribute to hypochloremia.


title: Electrolyte imbalance

text: Patients are usually asymptomatic with mild hypochloremia. Symptoms associated with hypochloremia are usually caused by the underlying cause of this electrolyte imbalance.


title: Electrolyte imbalance

text: Magnesium is mostly found in the bones and within cells. Approximately 1% of total magnesium in the body is found in the blood. Magnesium is important in control of metabolism and is involved in numerous enzyme reactions. A normal range is 0.70 - 1.10 mmol/L. The kidney is responsible for maintaining the magnesium levels in this narrow range.


title: Electrolyte imbalance

text: Hypermagnesemia, or abnormally high levels of magnesium in the blood, is relatively rare in individuals with normal kidney function. This is defined by a magnesium concentration >2.5 mg/dL.


title: Electrolyte imbalance

text: Hypermagnesemia typically occurs in individuals with abnormal kidney function. This imbalance can also occur with use of antacids or laxatives that contain magnesium. Most cases of hypermagnesemia can be prevented by avoiding magnesium-containing medications.


title: Electrolyte imbalance

text: Mild symptoms include nausea, flushing, tiredness. Neurologic symptoms are seen most commonly including decreased deep tendon reflexes. Severe symptoms include paralysis, respiratory failure, and bradycardia progressing to cardiac arrest.


title: Electrolyte imbalance

text: If kidney function is normal, stopping the source of magnesium intake is sufficient. Diuretics can help increase magnesium excretion in the urine. Severe symptoms may be treated with dialysis to directly remove magnesium from the blood.


title: Electrolyte imbalance

text: Hypomagnesemia, or low magnesium levels in the blood, can occur in up to 12% of hospitalized patients. Symptoms or effects of hypomagnesemia can occur after relatively small deficits.


title: Electrolyte imbalance

text: Major causes of hypomagnesemia are from gastrointestinal losses such as vomiting and diarrhea. Another major cause is from kidney losses from diuretics, alcohol use, hypercalcemia, and genetic disorders. Low dietary intake can also contribute to magnesium deficiency.


title: Electrolyte imbalance

text: Hypomagnesemia is typically associated with other electrolyte abnormalities, such as hypokalemia and hypocalcemia. For this reason, there may be overlap in symptoms seen in these other electrolyte deficiencies. Severe symptoms include arrhythmias, seizures, or tetany.


title: Electrolyte imbalance

text: The first step in treatment is determining whether the deficiency is caused by a gastrointestinal or kidney problem. People with no or minimal symptoms are given oral magnesium; however, many people experience diarrhea and other gastrointestinal discomfort. Those who cannot tolerate or receive magnesium, or those with severe symptoms can receive intravenous magnesium.


title: Electrolyte imbalance

text: Hypomagnesemia may prevent the normalization of other electrolyte deficiencies. If other electrolyte deficiencies are associated, normalizing magnesium levels may be necessary to treat the other deficiencies.


title: Electrolyte imbalance

text: Potassium resides mainly inside the cells of the body, so its concentration in the blood can range anywhere from 3.5 mEq/L to 5 mEq/L. The kidneys are responsible for excreting the majority of potassium from the body. This means their function is crucial for maintaining a proper balance of potassium in the blood stream.


title: Electrolyte imbalance

text: Hyperkalemia means the concentration of potassium in the blood is too high. This occurs when the concentration of potassium is >5 mEq/L. It can lead to cardiac arrhythmias and even death. As such it is considered to be the most dangerous electrolyte disturbance.


title: Electrolyte imbalance

text: Hyperkalemia is typically caused by decreased excretion by the kidneys, shift of potassium to the extracellular space, or increased consumption of potassium rich foods in patients with kidney failure. The most common cause of hyperkalemia is lab error due to potassium released as blood cells from the sample break down. Other common causes are kidney disease, cell death, acidosis, and drugs that affect kidney function.


title: Electrolyte imbalance

text: Part of the danger of hyperkalemia is that it is often asymptomatic, and only detected during normal lab work done by primary care physicians. As potassium levels get higher, individuals may begin to experience nausea, vomiting, and diarrhea. Patients with severe hyperkalemia, defined by levels above 7 mEq/L, may experience muscle cramps, numbness, tingling, absence of reflexes, and paralysis. Patients may experience arrhythmias that can result in death.


title: Electrolyte imbalance

text: There are three mainstays of treatment of hyperkalemia. These are stabilization of cardiac cells, shift of potassium into the cells, and removal of potassium from the body. Stabilization of cardiac muscle cells is done by administering calcium intravenously. Shift of potassium into the cells is done using both insulin and albuterol inhalers. Excretion of potassium from the body is done using either hemodialysis, loop diuretics, or a resin that causes potassium to be excreted in the fecal matter.


title: Electrolyte imbalance

text: The most common electrolyte disturbance, hypokalemia means that the concentration of potassium is <3.5 mEq/L. It often occurs concurrently with low magnesium levels.


title: Electrolyte imbalance

text: Low potassium is caused by increased excretion of potassium, decreased consumption of potassium rich foods, movement of potassium into the cells, or certain endocrine diseases. Excretion is the most common cause of hypokalemia and can be caused by diuretic use, metabolic acidosis, diabetic ketoacidosis, hyperaldosteronism, and renal tubular acidosis. Potassium can also be lost through vomiting and diarrhea.


title: Electrolyte imbalance

text: Hypokalemia is often asymptomatic, and symptoms may not appear until potassium concentration is <2.5 mEq/L. Typical symptoms consist of muscle weakness and cramping. Low potassium can also cause cardiac arrythmias.


title: Electrolyte imbalance

text: Hypokalemia is treated by replacing the body's potassium. This can occur either orally or intravenously. Because low potassium is usually accompanied by low magnesium, patients are often given magnesium alongside potassium.


title: Electrolyte imbalance

text: Sodium is the most abundant electrolyte in the blood. Sodium and its homeostasis in the human body is highly dependent on fluids. The human body is approximately 60% water, a percentage which is also known as total body water. The total body water can be divided into two compartments called extracellular fluid (ECF) and intracellular fluid (ICF). The majority of the sodium in the body stays in the extracellular fluid compartment. This compartment consists of the fluid surrounding the cells and the fluid inside the blood vessels. ECF has a sodium concentration of approximately 140 mEq/L. Because cell membranes are permeable to water but not sodium, the movement of water across membranes affects the concentration of sodium in the blood. Sodium acts as a force that pulls water across membranes, and water moves from places with lower sodium concentration to places with higher sodium concentration. This happens through a process called osmosis. When evaluating sodium imbalances, both total body water and total body sodium must be considered.


title: Electrolyte imbalance

text: Hypernatremia means that the concentration of sodium in the blood is too high. An individual is considered to be having high sodium at levels above 145 mEq/L of sodium. Hypernatremia is not common in individuals with no other health concerns. Most individuals with this disorder have either experienced loss of water from diarrhea, altered sense of thirst, inability to consume water, inability of kidneys to make concentrated urine, or increased salt intake.


title: Electrolyte imbalance

text: There are three types of hypernatremia each with different causes. The first is dehydration along with low total body sodium. This is most commonly caused by heatstroke, burns, extreme sweating, vomiting, and diarrhea. The second is low total body water with normal body sodium. This can be caused by diabetes insipidus, renal disease, hypothalamic dysfunction, sickle cell disease, and certain drugs. The third is increased total body sodium which is caused by increased ingestion, Conn's syndrome, or Cushing's syndrome.


title: Electrolyte imbalance

text: Symptoms of hypernatremia may vary depending on type and how quickly the electrolyte disturbance developed. Common symptoms are dehydration, nausea, vomiting, fatigue, weakness, increased thirst, excess urination. Patients may be on medications that caused the imbalance such as diuretics or nonsteroidal anti-inflammatory drugs. Some patients may have no obvious symptoms at all.


title: Electrolyte imbalance

text: It is crucial to first assess the stability of the patient. If there are any signs of shock such as tachycardia or hypotension, these must be treated immediately with IV saline infusion.  Once the patient is stable, it is important to identify the underlying cause of hypernatremia as that may affect the treatment plan. The final step in treatment is to calculate the patients free water deficit, and to replace it at a steady rate using a combination of oral or IV fluids.  The rate of replacement of fluids varies depending on how long the patient has been hypernatremic. Lowering the sodium level too quickly can cause cerebral edema.


title: Electrolyte imbalance

text: Hyponatremia means that the concentration of sodium in the blood is too low. It is generally defined as a concentration lower than 135 mEq/L. This relatively common electrolyte disorder can indicate the presence of a disease process, but in the hospital setting is more often due to administration of Hypotonic fluids. The majority of hospitalized patients only experience mild hyponatremia, with levels above 130 mEq/L. Only 1-4% of patients experience levels lower than 130 mEq/L.


title: Electrolyte imbalance

text: Hyponatremia has many causes including heart failure, chronic kidney disease, liver disease, treatment with thiazide diuretics, psychogenic polydipsia, syndrome of inappropriate antidiuretic hormone secretion. It can also be found in the postoperative state, and in the setting of accidental water intoxication as can be seen with intense exercise. Common causes in pediatric patients may be diarrheal illness, frequent feedings with dilute formula, water intoxication via excessive consumption, and enemas. Pseudohyponatremia is a false low sodium reading that can be caused by high levels of fats or proteins in the blood. Dilutional hyponatremia can happen in diabetics as high glucose levels pull water into the blood stream causing the sodium concentration to be lower. Diagnosis of the cause of hyponatremia relies on three factors: volume status, plasma osmolality, urine sodium levels and urine osmolality.


title: Electrolyte imbalance

text: Many individuals with mild hyponatremia will not experience symptoms. Severity of symptoms is directly correlated with severity of hyponatremia and rapidness of onset. General symptoms include loss of appetite, nausea, vomiting, confusion, agitation, and weakness. More concerning symptoms involve the central nervous system and include seizures, coma, and death due to brain herniation. These usually do not occur until sodium levels fall below 120 mEq/L.


title: Electrolyte imbalance

text: Considerations for treatment include symptom severity, time to onset, volume status, underlying cause, and sodium levels. If the sodium level is <120 mEq/L, the person can be treated with hypertonic saline as extremely low levels are associated with severe neurological symptoms. In non-emergent situations, it is important to correct the sodium slowly to minimize risk of osmotic demyelination syndrome. If a person has low total body water and low sodium they are typically given fluids. If a person has high total body water (such as due to heart failure or kidney disease) they may be placed on fluid restriction, salt restriction, and treated with a diuretic. If a person has a normal volume of total body water, they may be placed on fluid restriction alone.


title: Electrolyte imbalance

text: Diet significantly contributes to electrolyte stores and blood levels. Below are a list of foods that are associated with higher levels of these electrolytes.


title: Electrolyte imbalance

text: It is recommended that an individual consumes less than 2,300 mg of sodium daily as part of a healthy diet. A significant portion of our sodium intake comes from a just a few types of food, which can be surprising as large sources of sodium may not taste salty.


title: Electrolyte imbalance

text: In minerals, phosphorus generally occurs as phosphate. Good sources of phosphorus includes baking powder, instant pudding, cottonseed meal, hemp seeds, fortified beverages, dried whey.


title: Electrolyte imbalance

text: Good sources of potassium are found in a variety of fruits and vegetables. Recommend potassium intake for adults ranges from 2,300 mg to 3,400 mg depending on age and gender.


title: Electrolyte imbalance

text: Dairy is a major contributor of calcium to diet in the United States. The recommended calcium intake for adults range from 1,000 mg to 1,300 mg depending on age and gender.


title: Electrolyte imbalance

text: Magnesium is found in a variety of vegetables, meats, and grains. Foods high in fiber generally are a source of magnesium. The recommended magnesium intake for adults range from 360 mg to 420 mg depending on age and gender.


title: Patricia Lake

text: Patricia Douras Van Cleve (June 8, 1919 – October 3, 1993), known as Patricia Lake, was an American actress and radio comedian. Presented as the niece of actress Marion Davies, she was long suspected of being her natural daughter, fathered by publishing magnate William Randolph Hearst. Lake acknowledged this relationship shortly before she died.


title: Patricia Lake

text: She was born in a hospital outside Paris, France. Her date of birth is not known; according to her "Los Angeles Times" obituary, "The year was sometime between 1920 and 1923; Lake never knew exactly." The Social Security Death Index states she was born June 8, 1919.


title: Patricia Lake

text: In the 1920s, speculation arose that Lake was the child of Hearst and Davies, who had carried on a public affair since 1917. Hearst never divorced from his wife, Millicent Willson, whom he married in 1903, but the couple maintained separate lives.


title: Patricia Lake

text: Many reference books say that Lake's parents were Marion Davies' sister Rose and her first husband, George Van Cleve. The Lake family asserted that the newborn was given to Davies' sister, whose own child had died in infancy. The dead child's birth certificate was reportedly altered to support the deception. CBS News reported that Hearst acknowledged to Lake on her wedding day that he was her father.


title: Patricia Lake

text: According to "Magazine Americana", published by the Institute for the Study of American Popular Culture, after Rose and George Van Cleeve had separated, he kidnapped Patricia in 1924 and went into hiding. Hearst's detectives located the pair after five years and the girl was returned to Rose's custody. She was returned to Van Cleeve's custody after a court decision.


title: Patricia Lake

text: Patricia attended Lawlor Professional School in Hollywood. The Lake family asserts that when Patricia lived with the Van Cleeves, Hearst paid the bills and arranged for her education at schools in New York and Boston.


title: Patricia Lake

text: Hearst and Davies reportedly took Patricia on trips to Europe and spent time with her. Lake spent considerable time at Hearst's San Simeon estate, is included in most home movies of Hearst and Davies, and accompanied them on many trips. Introduced as Marion Davies' niece, Lake socialized with such notables as Clark Gable, Jean Harlow, Charlie Chaplin and Gloria Swanson. Lake lived with Marion Davies for the major portion of her life, and Hearst financially supported Lake all of her life. After Lake's marriage, Davies continued to support both Patricia and her husband Arthur. When Davies died in 1961, half of her $20 million estate was left to Lake as an inheritance.


title: Patricia Lake

text: Her features, "suspiciously similar" to those of Hearst, did not go unnoticed. Lake never made any public comment on the subject, even after the deaths of Hearst and Davies. Lakes's son said that hours before her death in 1993, she confirmed and asked her family to publish the identities of her biological parents.


title: Patricia Lake

text: Patricia first met actor Arthur Lake when he was visiting at Marion Davies's beach house. They married in 1937 at Hearst's San Simeon estate. Davies and Hearst jointly gave her away at the marriage ceremony. (This would have made her 13 or 14 years old at the time of her marriage if she was born in 1923; 17 or 18 if born in 1919.) Patricia and Arthur remained married for nearly 50 years until his death in January 1987. They had two children: Arthur Patrick Lake (Arthur Lake Jr.) (born March 1, 1943), and Marion Rose Lake (born October 6, 1944).


title: Patricia Lake

text: Both Patricia and her husband are interred in the same crypt as Marion Davies at the Hollywood Forever Cemetery.


title: Patricia Lake

text: Lake performed in theater during the late 1930s through the mid-1940s. When, after seven years, Penny Singleton left the radio sitcom "Blondie" in the mid-1940s, Lake replaced her as the voice of Blondie Bumstead for the remaining five years of the show, opposite her real-life husband Arthur Lake, who played Blondie's spouse, Dagwood. In 1954, Lake also co-starred with her husband in an early television sitcom he created called "Meet the Family".


title: Patricia Lake

text: Lake was selected by the Motion Picture Publicists Association to be one of the MPPA 'Baby Stars' of 1940, an award similar to the WAMPAS Baby Stars selections of 1922 through 1934.


title: Aadesh Shrivastava

text: Aadesh Shrivastava (4 September 1964 – 5 September 2015) was a music composer and singer of Indian music. Initially, he had worked as a drummer to music composers including R. D. Burman, Rajesh Roshan before working independently as a music director. Over the course of his career, he had composed music for over 100 Hindi films. Just a day after he turned 51, he died of cancer in Kokilaben Hospital.


title: Aadesh Shrivastava

text: Born in a Hindu Kayastha family in Katni, Shrivastava got his first big break with the film "Kanyadaan" in 1993. Among the singers who sang in this movie, there was Lata Mangeshkar who sang his first song - Oh Sajna Dilbar, a duet with Udit Narayan, which became popular on the radio. But the film and the rest of the songs went unnoticed. The same thing happened with "Jaane Tamanna", but he bounced back with "Aao Pyaar Karen". One track "Haathon Mein Aa Gaya Jo Kal" was a hit. His other films are "Salma Pe Dil Aa Gaya" and "Shastra". The song "Kya Ada Kya Jalwe Tere Paro", from the film "Shastra" got him in the limelight once again. In 1995, Shrivastava was a judge on "Sa Re Ga Ma Pa".


title: Aadesh Shrivastava

text: Shrivastava sang a number of hit songs such as "Sona Sona", "Shava Shava", "Gustakhiyaan" and "Gur Nalon Ishq Mitha". He won accolades for his work in "Kunwara", "Tarkieb" and "Shikari" in the year 2000. In 2001, his success continued with the movie "Bas Itna Sa Khwaab Hai". In 2005, he was a judge on the talent hunt show "Sa Re Ga Ma Pa Challenge 2005". The following year, he turned to direction with his short film on child prostitution, "Sanaa". In 2009, he made a cameo in the film "World Cupp 2011" and returned to television as a judge on "Sa Re Ga Ma Pa Challenge 2009". His semi-classical song "Mora Piya" from "Raajneeti" became a hit in 2010.


title: Aadesh Shrivastava

text: On the international front, Shrivastava has collaborated with artists such as Akon, Julia Fordham and Wyclef Jean. Together with Akon, he has launched an India-wide talent search on the website hitlab.com which uses music analysis technology to predict the hit potential of new songs.


title: Aadesh Shrivastava

text: Shrivastava was married to Vijayta Pandit, actress and sister of music composer duo Jatin and Lalit Pandit and actress Sulakshana Pandit in 1990. They have two sons, Anivesh and Avitesh. His elder brother, Chitresh Shrivastava, owned Eyeline Telefilm and Events, the event management company implicated in the Rahat Fateh Ali Khan black money incident. Chitresh died in a car accident in 2011.


title: Aadesh Shrivastava

text: It was reported in the media on 31 August 2015 that his cancer had relapsed for the third time since 2010 and that he had been hospitalised for more than a month. He died, in a coma, at 12:30 A.M. IST at Kokilaben Dhirubhai Ambani Hospital & Medical Research Institute, Mumbai, on 5 September 2015, a day after his 51st birthday. He was cremated at Oshiwara crematorium in Mumbai the same day.


title: Handyman

text: A handyman, also known as a fixer, handyperson or handyworker, is a person skilled at a wide range of repairs, typically around the home. These tasks include trade skills, repair work, maintenance work, are both interior and exterior, and are sometimes described as "side work", "odd jobs" or "fix-up tasks". Specifically, these jobs could be light plumbing jobs such as fixing a leaky toilet or light electric jobs such as changing a light fixture or bulb.


title: Handyman

text: The term "handyman" increasingly describes a paid worker, but it also includes non-paid homeowners or do-it-yourselfers. The term "handyman" is also occasionally applied as an adjective to describe politicians or business leaders who make substantial organizational changes, such as overhauling a business structure or administrative division.


title: Handyman

text: Many people can do common household repairs. There are resources on the Internet, as well as do-it-yourself guide books, with instructions about how to complete a wide range of projects. Sometimes the fix-it skill is seen as genetic, and people lacking such skills are said to "lack the handy-man gene". One trend is that fewer homeowners are inclined to do fix-up jobs, perhaps because of time constraints, perhaps because of lack of interest; one reporter commented "my family's fix-it gene petered out before it reached my generation."


title: Handyman

text: Historically being a handyman was considered a less prestigious occupation than a specialist such as a plumber, electrician, or carpenter. With the emergence of large national chains, there have been efforts to change that perception by emphasizing the professionalism of the trade and that a handyman is a technician with multiple skills and a wide range of knowledge. Handyman tools sometimes become useful in different places: for example, when a proper cranial drill was not available, an Australian doctor used a handyman's drill in 2009 to open a hole in the head of a 13-year-old boy to relieve pressure after a brain injury; the boy's life was saved.


title: Handyman

text: Tasks range from minor to major, from unskilled to highly skilled, and include painting, drywall repair, remodeling, minor plumbing work, minor electrical work, household carpentry, sheetrock, crown moulding, and furniture assembly (see more complete list below.)


title: Handyman

text: An estimate was that in 2003, the market for home-maintenance and repair spending was up 14% from 2001 to 2003. Another estimate was that the market in the United States was $126 billion and was increasing by about 4% annually. American homes are aging; one estimate was that in 2007, more than half of all homes are older than 25 years. And, as populations worldwide tend to become older, on average, and since increasingly elderly people will be less inclined and able to maintain their homes, it is likely that demand for handyman services will grow.


title: Handyman

text: Many towns have handymen who work part-time, for friends or family or neighbors, who are skilled in a variety of tasks. Sometimes they advertise in newspapers or online. They vary in quality, professionalism, skill level, and price. Contractors often criticize the work of previous contractors, and this practice is not limited to handymen, but to all trades. Handymen have advertised their services through flyers and mailings; in addition, free websites such as Craigslist and SkillSlate help customers and handymen find each other.


title: Handyman

text: In 2009, there were national handyman service firms which handle such nationwide tasks as public relations, marketing, advertising, and signage, but sell specific territories to franchise owners. A franchise contract typically gives a franchise owner the exclusive right to take service calls within a given geographical area. The websites of these firms put possible customers in touch with local owners, which have handymen and trucks. Customers call the local numbers. Typically these firms charge around $100/hour, although fees vary by locality and time of year. In many parts of the world, there are professional handyworker firms that do small home or commercial projects which claim possible advantages such as having workers who are insured and licensed. Their branch offices schedule service appointments for full-time and part-time handymen to visit and make repairs, and sometimes coordinate with sub-contractors.


title: Handyman

text: One Lehman Brothers executive, after being let go from the Wall Street firm, bought a Union, New Jersey franchise from a national handyman firm. A franchise was approximately $110,000 with a franchise fee of $14,900, according to a spokesperson for a national handyman franchise.


title: Handyman

text: Some see a benefit of franchising as "entrepreneurship under the safety net of a tried-and-true business umbrella" but forecast a 1.2 percent decrease in franchise businesses during the 2008–2009 recession. In 2005, according to a survey released by the Washington-based International Franchise Association showed 909,000 franchised establishments in the United States employing some 11 million people. Franchises offer training, advertising and information technology support, lower procurement costs and access to a network of established operators.


title: Handyman

text: Franchise handyman firms sometimes pitch clients by asking prospective customers about their unresolved "to-do lists". The firm does odd jobs, carpentry, and repairs. Trends such as a "poverty of time" and a "glut of unhandy husbands" has spurred the business. Technicians do a range of services including tile work, painting, and wallpapering. "One firm" charges $88 per hour. The firm targets a work category which full-fledged remodelers and contractors find unprofitable. A consumer was quoted by a reporter explaining the decision to hire one firm: "'I couldn't find anyone to come in and help me because the jobs were too small', said Meg Beck of Huntington, who needed some painting and carpentry done. She turned to one franchise firm and said she liked the fact that the service has well-marked trucks and uniformed technicians and that a dispatcher called with the names of the crew before they showed up." There are indications that these businesses are growing. There are different firms operating.


title: Handyman

text: Other competitors include online referral services. In addition, some large home centers offer installation services for products such as cabinets and carpet installation. Sometimes homeowners contact a professional service after trying, but failing, to do repair work themselves; in one instance, a Minneapolis homeowner attempted a project but called a technician to finish the project, and the overall cost was substantial.


title: Handyman

text: How well do the franchise chains perform? One Wall Street Journal reporting team did an informal assessment by hiring handymen all over the United States and asking them to fix a wide range of problems, from a relatively routine leaky faucet to a sticky door. The reporter concluded that "with few licensing requirements and standards for the industry, prices are all over the board." One quote was ten times as large as another. Further, the reporter concluded: "A big corporate name is no guarantee of quality or speedy service." One corporate firm took three weeks to fix a stuck door. Service varied from spotty to good, with complaints about unreturned phone calls, service people standing on dining room chairs, leaving holes between wood planking, but liked getting multiple jobs done instead of just one. Customers liked handymen wearing hospital booties (to avoid tracking dirt in houses). The reporter chronicled one experience with repairing a water-damaged ceiling. A franchise firm fixed it for $1,530; a second (non-franchise local handyman) fixed a similar ceiling for $125. The reporter preferred the second worker, despite the fact that he "doesn't have a fancy van – or carry proof of insurance". Tips for selecting a good handyman include: Do your homework, check out reviews and do an online search to find out as much as you can about the person who will come to your house. For small jobs, the cheapest way is to pay time and material. You can't expect someone to spend an hour driving to your house for a couple of hours of work. Ask questions, get written estimates on company stationery, make sure handymen guarantee their work, pay with credit cards or checks because this provides an additional record of each transaction, check references and licenses, review feedback about the contractors from Internet sites. To find a competent worker, one can seek referrals from local sources such as a school or church or office park, to see if a staff handyman does projects on the side, as well as ask friends for referrals; a general contractor might have workers who do projects on the side as well. Further, one can try out a new handyman with easy projects such as cleaning gutters to see how well they perform.


title: Handyman

text: Generally, in the United States, there are few legal issues if an unpaid homeowner works on a project within their own home, with some exceptions. Some jurisdictions require paid handymen to be licensed and/or insured. New Jersey, for example, requires all handymen who work in for-profit businesses serving residential and commercial customers, to be registered and insured. Often handymen are barred from major plumbing, electrical wiring, or gas-fitting projects for safety reasons, and authorities sometimes require workers to be licensed in particular trades. However, minor plumbing work such as fixing water taps, connecting sinks, fixing leaks, or installing new washing machines, are usually permitted to be done without licensing. Many handymen are insured under a property damage liability policy, so that accidental property damage from negligence or accidents are covered.


title: Handyman

text: The handyman image recurs in popular culture. There have been songs about handymen recorded by Elvis Presley in 1964, Del Shannon in 1964, James Taylor in 1977. There are femme-fatale TV characters who fall for handymen. Handymen have been portrayed in books and films, generally positively, as do-gooder helpful types, but not particularly smart or ambitious. In a book by author Carolyn See called "The Handyman", a handyman is really an aspiring but discouraged artist who transforms the lives of people he works for, as well as having sexual encounters with some of his clients, and his experiences improve his artistic output. The book suggests handymen discover "the appalling loneliness of the women who call him for help" whose needs are sometimes "comic," sometimes "heartbreaking," and deep down "sexual". A 1980 movie called "The Handyman" was about a carpenter-plumber who was "good at what he does" but is "too honest and trusting," and gets taken advantage of by "women who find him handsome and understanding;" the movie earned negative reviews from critic Vincent Canby. Other movies have used a rather tired formula of sexy-handyman meets bored-housewives, such as "The Ups and Downs of a Handyman", a 1975 movie in which "Handsome Bob also finds he's a fast favorite with the local housewives, who seem to have more than small repairs on their minds." In Canada, there's a television show called "Canada's Worst Handyman" which is a reality show in which handyman contestants try their best on jobs in order to "not" be labeled "worst handyman". "Home Improvement" is an American television sitcom starring Tim Allen, which aired 1991 to 1999. On the children's television show Mister Rogers' Neighborhood, Handyman Negri was one of the characters residing in The Neighborhood of Make-Believe, as well as the neighborhood Mister Rogers resides in. "Handy Manny" is an American/Hispanic preschool television show that airs on "Playhouse Disney" and stars a handyman cartoon character named Manny. The Belgian comics and media franchise "The Smurfs" depicts Handy Smurf with traditional handyman's accoutrements, such as overalls, carpenter's pencil and work hat. "Happy Tree Friends" also has an orange beaver named Handy who is a handyman.


title: Handyman

text: Two handymen are also the main characters in the Czechoslovak, later Czech, stop-motion animated series "Pat & Mat".


title: Handyman

text: The list of projects which handymen can do is extensive, and varies from easy-to-learn tasks which take little time such as changing a light bulb, to extensive projects which require multiple steps, such as kitchen remodeling. Here is a partial list:


title: Michael Stahl-David

text: Michael Stahl-David (born October 28, 1982) is an American actor, known for his role as Sean Donnelly on the NBC drama series "The Black Donnellys" and his lead role as Robert "Rob" Hawkins in the J. J. Abrams-produced film "Cloverfield" and the fanmade short film "The Cloverfield Files".


title: Michael Stahl-David

text: Stahl-David was born in Chicago, Illinois, the son of physicians. He graduated from Columbia College Chicago. He is the older brother to Eric Stahl-David and R. Andrew Stahl-David, both of whom graduated from Whitney Young Magnet High School. Prior to his acting career, Stahl-David was a graffiti artist in Chicago.


title: Michael Stahl-David

text: Stahl-David began his acting career in 2001, when he played a minor role of Rossetti in "New Port South". Later in 2003, he also played a minor role as Craig in "Uncle Nino". During this time he was active in the Chicago theater scene, appearing in plays at the Steppenwolf Theatre ("One Arm", "Theater District"), Victory Gardens Theater ("Cider House Rules", "Lost in Yonkers"), and the Goodman Theatre ("The Goat, or Who Is Sylvia?") Shortly after arriving in New York in 2005, he appeared as Peter in "The Diary of Anne Frank" at the Papermill Playhouse. In the winter of 2007 he enjoyed critical success in his role in "The Overwhelming" Off-Broadway. Stahl-David began his television acting career in 2007, when he made a guest appearance as Riordan Grady in the series "" episode "Players". Later in 2007, he portrayed Sean Donnelly, one of the four Irish brothers, in the short-lived series "The Black Donnellys". His most recent film appearance was in J.J. Abrams' "Cloverfield" reprising his role as Rob. In September 2008, Stahl-David starred in and directed the web series "Michael Stahl-David: Behind the Star" on Crackle.


title: Michael Stahl-David

text: In 2010, Stahl-David starred in the ABC mockumentary series "My Generation", which was cancelled after two episodes due to low ratings. Stahl-David starred as Kevin in the Off-Broadway play "Picked" at New York City's Vineyard Theatre from April 6 to May 15, 2011. Stahl-David also starred in the 2014 paranormal romance film "In Your Eyes" as one of the lead roles.


title: Springfield Armory XD

text: The Springfield Armory XD is a series of semi-automatic pistols sold by Springfield Armory, Inc., in the United States along with follow-on variants: XD-M, XD-S, and XD-E. Polymer-framed and predominantly striker-fired, the series is manufactured by HS Produkt in Karlovac, Croatia.


title: Springfield Armory XD

text: In 2002, Springfield Armory, Inc., negotiated licensing rights to the United States market for the polymer-frame striker-fired HS2000 pistol being manufactured in Croatia by HS Produkt.


title: Springfield Armory XD

text: Using XD (eXtreme Duty) branding, Springfield Armory subsequently expanded the series to include ten models in three different calibers and five different cartridges, seven barrel lengths, and six finishes (black, black bi-tone, olive drab, olive drab bi-tone, flat dark earth, and flat dark earth bi-tone). The XD sub-compact was named "Pistol of the Year" by "American Rifleman" for 2003, followed by the XD chambered in .45 ACP being named "Handgun of the Year" by both "American Rifleman" and the Shooting Industry Academy of Excellence for 2006.


title: Springfield Armory XD

text: The variant (where 'M' represents match grade) was introduced in mid-2008; it won "Handgun of the Year" from "American Rifleman" for 2009. The most noticeable differences from the original XD models are the interchangeable back-straps and match-grade barrel. The first XD-M was chambered in .40 S&W with a barrel, holding 16 rounds in the magazine. This was soon followed by 9×19mm Parabellum (9mm) and .45 ACP chamberings. In 2018, 10mm Auto was added. The XD-M series is also produced as compact pistols in .40 S&W, .45 ACP and 9mm with barrels. A "competition" series is chambered in 9mm, 10mm Auto, .40 S&W, and .45 ACP with a barrel, remotely resembling the tactical XD pistols with barrels.


title: Springfield Armory XD

text: In January 2012, Springfield Armory announced a new variant, marketed as the XD-S. The 'S' represents the single-stack magazine used, providing a slimmer grip. While sharing many features with the original XD and XD-M, the XD-S included a new pre-set trigger and a disassembly fail-safe, neither of which were available in XD or XD-M models. The fail-safe disassembly prevents the disassembly lever from being manipulated when there is a magazine in the pistol. Conversely, when the disassembly lever is up, a magazine cannot be inserted into the pistol. This model, at only wide and initially available only in .45 ACP, is specifically designed for concealed carry. The .45 ACP XD-S has a 5+1 capacity (with optional 6+1 and 7+1 magazines) and a barrel. In January 2013, an XD-S chambered in 9×19mm Parabellum (9mm) was introduced. It is the same as the .45 ACP model, the only difference being that the 9mm XD-S has a 7+1 capacity (with optional 8+1 and 9+1 magazines) and is marginally heavier due to a smaller barrel bore.


title: Springfield Armory XD

text: In 2014, Springfield Armory unveiled the XD Mod.2, increasing their XD lineup to 33 offerings. The XD Mod.2 includes ergonomic improvements, the most notable of which is the "Grip Zone"; three differently textured areas on the grip, each with their own unique texturing, in contrast to the original XD design with traditional grip texturing. The pistol also has a new set of sights. Springfield Armory upgraded the front sight to a red fiber optic. The rear sight is still a two dot, though its profile has been lowered, and is still constructed of steel to facilitate its use in racking the slide.


title: Springfield Armory XD

text: In 2017, Springfield Armory added the XD-E, with the 'E' denoting that the variant uses an external hammer; operation is double action / single action (DA/SA). Originally offered in 9mm, a version chambered in .45 ACP was subsequently added.


title: Springfield Armory XD

text: In 2018, the company introduced a refresh to the XD-S, the XD-S Mod.2 variant. Included in the refresh are safeties on the grip and trigger. Also introduced in 2018 was an XD-M chambered in 10mm Auto.


title: Springfield Armory XD

text: Reception for the Springfield Armory XD has been largely positive. Many high-profile shooters and gun experts have spoken highly of the XD line, including Massad Ayoob and Ron Avery. Following the introduction of the XDM 5.25" model (which was designed with input by USPSA National Champion Rob Leatham) and, later, the XDM Elite series, the XD has steadily grown in popularity with the competition shooting market. The XDM Elite series, with further improvements designed for professional shooters such as a flared magwell, improved sights and increased capacity, continued the XD's rise in competitive popularity.


title: Springfield Armory XD

text: The XD-S in 9mm was named "Handgun of the Year" by "American Rifleman" for 2013. In 2021, the XDM Elite was awarded a Reader's Choice Award by "Ballistic’s Best" magazine.


title: Springfield Armory XD

text: , the XD series has been offered in four branding variants (XD, XD-M, XD-S, XD-E), with XD and XD-S also offered in second generation (Mod.2) configurations.


title: Springfield Armory XD

text: , for the XD series, the only offerings listed on the company's website are sub-compact (in 9mm and .40 S&W) and service models (in 9mm, .40 S&W, and .45 ACP).


title: Springfield Armory XD

text: , for the XD Mod.2 series, the only offerings listed on the company's website are sub-compact and service models, both in 9mm and .45 ACP.


title: Elevation Church

text: Elevation Church is a Baptist Evangelical multi-site megachurch pastored by Steven Furtick, based in Charlotte, North Carolina, affiliated with the Southern Baptist Convention. Weekly church attendance was 27,408 people in 2021. Elevation has 23 locations.


title: Elevation Church

text: The church began as a church plant of the Baptist State Convention of North Carolina, with Steven Furtick and seven other families from Christ Covenant Church in Shelby, North Carolina, relocated to Charlotte, North Carolina, meeting in Providence High School. On February 5, 2006, the first Sunday worship service, 121 people attended. By 2013, the church's regular attendance had grown to nearly 15,000 people weekly. According to a 2018 church census, it claimed a weekly attendance of 25,317 people and 16 campuses in different cities. As of 2022, Elevation averages 26,000 attendees, with an additional 65,000 attending on their online platform called eFam.


title: Elevation Church

text: Since 2006, Elevation Church has given more than $10 million. In 2011, a partnership with Charlotte Mayor Anthony Foxx was established to give 100,000 hours and $750,000 to serve Charlotte people in "The Orange Initiative." In 2012, the church completed The Orange Initiative with over 102,000 hours served.


title: Elevation Church

text: In 2008, Elevation Church gave out $40,000 to members, in envelopes filled with $5, $20, even $1,000, and told them to spend it kindly on others.


title: Elevation Church

text: In 2012, Elevation Church launched an initiative calling for members to mentor children for the 2012–2013 school year, with over 1,600 responding. The school outreach program was criticized in local LGBT media.


title: Elevation Church

text: In 2020, Elevation Church partnered with NASCAR driver Joey Logano through his foundation to establish a $1 million COVID-19 Response and Recovery Fund. Elevation also teamed up with the Food Bank of Central and Eastern North Carolina, giving away 17,000 meals to people in need during the COVID-19 pandemic.


title: Elevation Church

text: Since 2010, Elevation Church has hosted a week-long outreach called "Love Week." During the church's 2010 "Love Week," Elevation members packed more than 10,000 sandwiches for the homeless, helped single mothers get their cars serviced, donated blood, cleaned up parks and streets, built a soccer field for local ministries and renovated buildings. In 2011, Elevation and over 25 other local churches served more than 34,000 hours in a single week. In 2012, Elevation partnered with 31 other churches to serve 62 outreach organizations for a total of 50,340 hours around the city of Charlotte, N.C. Elevation also partnered with Presbyterian Hospital-Matthews to help fund enhancements and expansion at a local free clinic. During Elevation's 2021 Love Week, the church had 22,651 volunteers help for a total of 47,465 hours, serving 314 organizations with 1,588 total events. Elevation Church donated 1.6 million to outreach partners, while the volunteers made 2,200 baby care kits, 5,600 dignity kits for women and teens, 21,000 backpacks for students, and distributed 30,900 snack packs.


title: Elevation Church

text: In 2014, Elevation Church has been criticized over its practice of selecting volunteers who wish to be baptized to do so during so-called "spontaneous baptism" services. In response to the initial coverage, Elevation released a statement, which reads in part: "We are confident that those who attend Elevation Church know and understand our mission and vision for reaching people for Jesus Christ. As attendees, they are provided, through weekly teachings, biblical context for everything we do and practice, such as baptism, giving, serving and inviting friends to church."


title: Femme

text: Femme (; , literally meaning "woman") is a term traditionally used to describe a lesbian who exhibits a feminine identity.


title: Femme

text: Heavily associated with lesbian history and culture, "femme" has been used among lesbians to distinguish traditionally feminine lesbians from their butch (i.e. masculine) lesbian counterparts and partners. Derived from American lesbian communities following World War II when women joined the work force, the identity became a characteristic of the working class lesbian bar culture of the 1940s–1950s. By the 1990s, the term "femme" had additionally been adopted by bisexual women.


title: Femme

text: Alternate meanings of the word also exist with some non-lesbian individuals using the word, notably some gay men, bisexuals, and transgender individuals.


title: Femme

text: Scholars Heidi M. Levitt and Sara K. Bridges state that the terms "butch" and "femme" are derived from the 1940s-1950s American lesbian communities following World War II "when women joined the work force and began wearing pants, creating the possibility for the development of a butch aesthetic and gender expression within gay women's communities." They state that "the butch-femme culture made lesbians visible for the first time."


title: Femme

text: Femme lesbian scholar Joan Nestle describes the femme lesbian identity as being underrepresented in historical records, with femme women having been often attacked for passing as straight while also being accused of imitating heteronormativity for pairing with a butch partner. In Nestle's text on femme identity, "The Femme Question", she challenges this commonly held belief by stating that butch-femme relationships are "filled with a deeply lesbian language of stance, dress, gesture, love, courage and autonomy." Arlene Istar Lev argues that through their subversive appropriation of heteronormative gender roles, these identities were considered "complex erotic and social statements" rooted in "gendered erotic identities". Nestle states that they publicly declared same-sex love between women at a time when there was no liberation movement to support or protect them, and adds that "in the 1950s particularly, butch-femme couples were the front-line warriors against sexual bigotry. Because they were so visible, they suffered the brunt of street violence. The irony of social change has made a radical, sexual, political statement of the 1950s appear today a reactionary, non feminist experience."


title: Femme

text: Lesbian feminism saw a rejection of the butch-femme dynamic and therefore femme identity. During the emergence of lesbian feminism, femme lesbians were accused by prominent lesbian feminist figures of aping patriarchal beauty standards for wearing traditional feminine clothing. Black lesbian feminist poet and activist Audre Lorde wrote in "Tar Beach" that "butch and femme role playing was the very opposite of what we felt being gay was all about – the love of women".


title: Femme

text: Many bisexual women also active in the lesbian community felt pressured to identify as "lesbian", resulting in bisexual erasure factoring into the history of "femme" identities. This is further impacted by the fact that bisexual communities and the related bisexual movement did not formalize until the 1970s.


title: Femme

text: During the 1990s and the emergence of the lipstick lesbian identity into the mainstream, "femme" became a catch-all term to describe a feminine lesbian. Citing research from the 1990s, Levitt and Bridges stated that the terms "butch" and "femme" "began infiltrating bisexual communities, and women began writing about their experiences as bisexual femmes", but also that "very little empirical research has been conducted looking at the expression and experience of gender expression and gender identity within bisexual women."


title: Femme

text: With expansion of the femme identity, sexual attraction differences between butches and femmes began to be analyzed. Scholars Cheris Kramarae and Dale Spender wrote, "Femme diversity is also manifested in the sexual arena. As many femmes may be attracted exclusively to butches, some are attracted to other femmes, and still others are also attracted to men and consider themselves bisexual." Some research has indicated that butches are more likely to be exclusively lesbian, while femmes are sometimes bisexual. In 2005, preliminary research conducted by Levitt and Bridges indicated that lesbians are more likely to identify as butch and have a more masculine gender expression than bisexual women. 4.5 percent of the bisexual women they studied identified as butch compared to the 30.1 percent of lesbians who did. Lesbians were more sexually attracted to women whose gender expressions contrasted theirs, and bisexual women were more sexually attracted to those whose gender expressions were more similar to theirs. Levitt and Bridges theorized that "this finding may be in part due to the different aesthetics that are available and popular within lesbian and bisexual communities."


title: Femme

text: The term "femme" has also been used to refer to gender non-conforming people who do not identify as lesbian or to transgender or non-binary people. In 1994, Kate Bornstein chronicled their experience as a gender non-conforming person who is a femme lesbian in their book "Gender Outlaw". Praising the publication of Ivan Coyote's "Persistence: All Ways Butch and Femme" in 2011, Bornstein said, "The butch/femme dynamic is a conscious, loving binary of desire and trust ... it's a dance of love and outlawed romance. Butches and femmes share a sense of tribe, extended family and kinship—no matter what our genders might be." Since the late 2010s, influenced by the emergence of queer and transgender culture on sites such as Tumblr, Everyday Feminism, and Autostraddle, "femme" has been expanded to describe feminine people across gender and sexuality categories including heterosexual women, cisgender men and transfeminine people.


title: Femme

text: The postmodern queer conception of femme is a femme-identified person who does not always dress or act in a "traditionally feminine" (meaning a feminine aesthetic, such as wearing makeup, heels, and numerous accessories) way, but who expresses femme identity through feminine-associated behaviours, interactions and political views. Rather than an erotic identity rooted in lesbian women's culture, queer femme has been reframed into a political identity that is inclusive of all who wish to identify with it, feminine-presenting or not. As femme has moved into the mainstream, it has also been connected to notions of emotional labor, witchcraft and self-empowerment.


title: Femme

text: Based on the understanding of "femme" as describing a person (not necessarily a woman) who presents femininely, the expression "women and femmes" is sometimes used, but it has been criticized as conflating two different categories of identity.


title: Femme

text: "Femme" has also been used to describe a form of contemporary feminism which rejects the gender binary and acknowledges that individuals can fall anywhere within the gender spectrum, resulting in the possibility to be gender-less, gender-fluid, femme or masculine of center. Often using the phrase "women and femmes", adherents to this definition of femme believe that misogyny is used not only against women to inflict theoretical and physical violence but primarily against all feminine people. Connecting cisgendered male violence to toxic masculinity, they believe that patriarchy not only negatively affects female-identified people but men as well.


title: Femme

text: Many prominent femme-identified voices in mainstream media tend to be transfeminine and or non-binary individuals. The term "femme" is also essential to ballroom culture through the terms "butch queen" and "femme queen", denoting a gay man and transgender woman respectively.


title: Femme

text: From the 70s through 90s, gay male culture included the phrase "No Fats, No Femmes", and that persists in queer dating culture today. Constrained by character limitations on gay hookup apps such as Grindr and Scruff, "fem", "femm", and "femme" are used as an abbreviation for feminine. The ubiquitous phrase "No Fats, No Fems", indicating that a user does not want to be contacted by men of a certain size or feminine men, has been challenged by those in the gay community for perpetuating homonormative beauty ideals. "Fem" is used as a descriptor of one's appearance or mannerisms.


title: Femme

text: Theorists have used aesthetics to analyze and addresses the evolution of the word “femme” throughout the 21st century. Femme theorist Andi Schwartz uses comparisons of modern and historical associations of the femme identity to outline “soft femme theory.” She asserts that in the mid-to-late 20th century, “femme” was used to describe rough, badass women. Today, however, especially on social media, the word “femme” is used to describe the “soft, sad girl” trope that is commonly seen online and in trending fashions. While Schwartz offers a critique of this aesthetic and the erasure of pre-internet femme identities, she also considers how “performing softness” as an identifier for femininity, both on and offline, can be effective in transgressing hegemonic gender norms.


title: Femme

text: The contemporary queer concepts of femme have been challenged by lesbians who still use the term based on its original meaning. With concern about the erasure of lesbian culture and history, it has been argued that taking a term from an already marginalised society is a form of misogynist appropriation that undervalues lesbian identities, history and women's autonomy to self-identify outside patriarchal structures.


title: Femme

text: In her paper, Femme Theory: Refocusing the Intersectional Lens, femme theorist Rhea Hoskin offers an intersectional framework of femme theory and addresses the capabilities of subversive femininities. She uses an intersectional lens to address discourse surrounding femme-phobia and the ways in which this issue is not taken seriously as a form of oppression within the queer community and especially in academic feminist queer spaces.


title: Bob Zmuda

text: Bob Zmuda (born December 12, 1949) is an American writer, comedian, producer, and director best known for his friendship with comedian Andy Kaufman.


title: Bob Zmuda

text: Bob Zmuda occasionally portrayed Kaufman's Tony Clifton character on stage and for television appearances. In a 2006 interview, Zmuda told the "Opie and Anthony Show" that he was masquerading as Tony Clifton with David Letterman, and that Letterman did not find out until years later.


title: Bob Zmuda

text: In 1986, Zmuda founded the American version of "Comic Relief", an annual event that raises money to help the homeless in the United States. The event was televised on HBO, and was hosted by comedians Robin Williams, Billy Crystal and Whoopi Goldberg.


title: Bob Zmuda

text: In 1999, Zmuda wrote a book about Kaufman's life, titled "Andy Kaufman Revealed!", which purported to unveil many tricks and hoaxes that the two pulled off in front of audiences and television cameras in the 1980s. One critic praised the book as "the ultimate insider's look at Kaufman's life," while some of Kaufman's fans and members of Kaufman's family criticized it for inaccuracies about Kaufman.


title: Bob Zmuda

text: Later that year, Miloš Forman directed "Man on the Moon", the story of Kaufman's life. Zmuda created the "Tony Clifton" makeup for the film, and made a brief appearance portraying comedian Jack Burns, one of the producers, who gets into a brawl on stage during one of Kaufman's appearances on the 1980–82 ABC late night comedy show, "Fridays". Zmuda was also "Man on the Moon"'s co-executive producer. On camera, the character of Bob Zmuda was played by Paul Giamatti. Stanley Kaufman, Andy's father, criticized Zmuda's influence on the film shortly after its release, writing in the form of Andy speaking from beyond the grave.


title: Bob Zmuda

text: Sam Simon, executive producer on "Taxi", revealed in a 2013 interview with Marc Maron for the WTF Podcast that the portrayal of Andy on the show was "a complete fiction" largely created by Bob Zmuda, who he maintained has a "vested interest" in creating stories about Kaufman. In the interview Simon stated that Kaufman was "completely professional" and that he "told you Tony Clifton was he", but conceded that Kaufman would have "loved" Zmuda's version of events.


title: Bob Zmuda

text: In 2014, Zmuda co-authored another book with new anecdotes about Kaufman's desire to fake his death entitled "Andy Kaufman: The Truth, Finally", which states that Kaufman's death was indeed a prank. Zmuda says that Kaufman is still alive and that Kaufman would soon be revealing himself as his upper limit on the prank was thirty years. Zmuda now states that Kaufman offered to leave him money since Zmuda's career was largely dependent on Kaufman performing but he turned it down because he believed it would implicate him in a crime. The terms of the book deal were not disclosed.


title: Bob Zmuda

text: On November 7, 2014, Bob Zmuda appeared as a guest on Greg Fitzsimmons' podcast, "Fitzdog Radio". During the interview, Zmuda claimed to have invested $50,000 in the new book. He stormed off the podcast after Fitzsimmons doubted Zmuda's intentions regarding claims of Kaufman's staged death.


title: Bob Zmuda

text: On November 16, 2014, a post on the Tony Clifton Facebook page claimed that Bob Zmuda had died at the Moonlite BunnyRanch, sourcing the information to a UPI article. The same day, the BunnyRanch tweeted that they had been asked by Zmuda's management not to comment, with a link to the hoax Facebook story.


title: Bob Zmuda

text: Two days later, comedy news website The Interrobang posted a story with photos, verifying that Zmuda was not dead. Later that day, UPI posted a story, confirming the hoax.


title: Coordinate-measuring machine

text: A coordinate measuring machine (CMM) is a device that measures the geometry of physical objects by sensing discrete points on the surface of the object with a probe. Various types of probes are used in CMMs, the most common being mechanical and laser sensors, though optical and white light sensor do exist. Depending on the machine, the probe position may be manually controlled by an operator or it may be computer controlled. CMMs typically specify a probe's position in terms of its displacement from a reference position in a three-dimensional Cartesian coordinate system (i.e., with XYZ axes). In addition to moving the probe along the X, Y, and Z axes, many machines also allow the probe angle to be controlled to allow measurement of surfaces that would otherwise be unreachable.


title: Coordinate-measuring machine

text: The typical 3D "bridge" CMM allows probe movement along three axes, X, Y and Z, which are orthogonal to each other in a three-dimensional Cartesian coordinate system. Each axis has a sensor that monitors the position of the probe on that axis, with typical accuracy in the order of microns. When the probe contacts (or otherwise detects) a particular location on the object, the machine samples the axis position sensors, thus measuring the location of one point on the object's surface, as well as the 3-dimensional vector of the measurement taken. This process is repeated as necessary, moving the probe each time, to produce a "point cloud" which describes the surface areas of interest. The points can be measured either manually by an operator or automatically via Direct Computer Control (DCC) or automatically using scripted programs; thus, an automated CMM is a specialized form of industrial robot.


title: Coordinate-measuring machine

text: A common use of CMMs is in manufacturing and assembly processes to test a part or assembly against the design intent. The measured points can be used to verify the distance between features. They can also be used to construct geometric features such as cylinders and planes etc. for GD&T such as roundness, flatness and perpendicularity can be assessed.


title: Coordinate-measuring machine

text: The accuracy of coordinate measurement machines are typically given as an uncertainty factor as a function over distance. For a CMM using a touch probe, this relates to the repeatability of the probe and the accuracy of the linear scales. Typical probe repeatability can result in measurements of within .001mm or .00005 inch (half a ten thousandth) over the entire measurement volume. For 3, 3+2, and 5 axis machines, probes are routinely calibrated using traceable standards and the machine movement is verified using gauges to ensure accuracy.


title: Coordinate-measuring machine

text: The first CMM was developed by the Ferranti Company of Scotland in the 1950s as the result of a direct need to measure precision components in their military products, although this machine only had 2 axes. The first 3-axis models began appearing in the 1960s (DEA of Italy / LK of the UK) and computer control debuted in the early 1970s but the first working CMM was developed and put on sale by Browne & Sharpe in Melbourne, England. (Leitz Germany subsequently produced a fixed machine structure with moving table.


title: Coordinate-measuring machine

text: In modern machines, the gantry-type superstructure has two legs and is often called a bridge. This moves freely along the granite table with one leg (often referred to as the inside leg) following a guide rail attached to one side of the granite table. The opposite leg (often outside leg) simply rests on the granite table following the vertical surface contour. Air bearings are the chosen method for ensuring friction free travel. In these, compressed air is forced through a series of very small holes in a flat bearing surface to provide a smooth but controlled air cushion on which the CMM can move in a near frictionless manner which can be compensated for through software. The movement of the bridge or gantry along the granite table forms one axis of the XY plane. The bridge of the gantry contains a carriage which traverses between the inside and outside legs and forms the other X or Y horizontal axis. The third axis of movement (Z axis) is provided by the addition of a vertical quill or spindle which moves up and down through the center of the carriage. The touch probe forms the sensing device on the end of the quill. The movement of the X, Y and Z axes fully describes the measuring envelope. Optional rotary tables can be used to enhance the approachability of the measuring probe to complicated workpieces. The rotary table as a fourth drive axis does not enhance the measuring dimensions, which remain 3D, but it does provide a degree of flexibility. Some touch probes are themselves powered rotary devices with the probe tip able to swivel vertically through more than 180 degrees and through a full 360 degree rotation.


title: Coordinate-measuring machine

text: CMMs are now also available in a variety of other forms. These include CMM arms that use angular measurements taken at the joints of the arm to calculate the position of the stylus tip, and can be outfitted with probes for laser scanning and optical imaging. Such arm CMMs are often used where their portability is an advantage over traditional fixed bed CMMs- by storing measured locations, programming software also allows moving the measuring arm itself, and its measurement volume, around the part to be measured during a measurement routine. Because CMM arms imitate the flexibility of a human arm they are also often able to reach the insides of complex parts that could not be probed using a standard three axis machine.


title: Coordinate-measuring machine

text: In the early days of coordinate measurement (CMM), mechanical probes were fitted into a special holder on the end of the quill. A very common probe was made by soldering a hard ball to the end of a shaft. This was ideal for measuring a whole range of flat face, cylindrical or spherical surfaces. Other probes were ground to specific shapes, for example a quadrant, to enable measurement of special features. These probes were physically held against the workpiece with the position in space being read from a 3-axis digital readout (DRO) or, in more advanced systems, being logged into a computer by means of a footswitch or similar device. Measurements taken by this contact method were often unreliable as machines were moved by hand and each machine operator applied different amounts of pressure on the probe or adopted differing techniques for the measurement.


title: Coordinate-measuring machine

text: A further development was the addition of motors for driving each axis. Operators no longer had to physically touch the machine but could drive each axis using a handbox with joysticks in much the same way as with modern remote controlled cars. Measurement accuracy and precision improved dramatically with the invention of the electronic touch trigger probe. The pioneer of this new probe device was David McMurtry who subsequently formed what is now Renishaw plc. Although still a contact device, the probe had a spring-loaded steel ball (later ruby ball) stylus. As the probe touched the surface of the component the stylus deflected and simultaneously sent the X,Y,Z coordinate information to the computer. Measurement errors caused by individual operators became fewer and the stage was set for the introduction of CNC operations and the coming of age of CMMs.


title: Coordinate-measuring machine

text: Optical probes are lens-CCD-systems, which are moved like the mechanical ones, and are aimed at the point of interest, instead of touching the material. The captured image of the surface will be enclosed in the borders of a measuring window, until the residue is adequate to contrast between black and white zones. The dividing curve can be calculated to a point, which is the wanted measuring point in space. The horizontal information on the CCD is 2D (XY) and the vertical position is the position of the complete probing system on the stand Z-drive (or other device component).


title: Coordinate-measuring machine

text: There are newer models that have probes that drag along the surface of the part taking points at specified intervals, known as scanning probes. This method of CMM inspection is often more accurate than the conventional touch-probe method and most times faster as well.


title: Coordinate-measuring machine

text: The next generation of scanning, known as noncontact scanning, which includes high speed laser single point triangulation, laser line scanning, and white light scanning, is advancing very quickly. This method uses either laser beams or white light that are projected against the surface of the part. Many thousands of points can then be taken and used not only to check size and position, but to create a 3D image of the part as well. This "point-cloud data" can then be transferred to CAD software to create a working 3D model of the part. These optical scanners are often used on soft or delicate parts or to facilitate reverse engineering.