bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of the Lacrimal System
Authors: Linberg John V.
Published: November 2020

The common complaint of a watering eye may be caused by a variety of problems, including lacrimal hyposecretion, lacrimal hypersecretion, or blockage of the lacrimal drainage system. This system is a complex membranous channel whose function depends on the interaction of anatomy and physiology. Effective tear drainage depends on a variety of factors, including the volume of tear secretion, eyelid position, and anatomy of the lacrimal drainage passages. Epiphora is defined as an abnormal overflow of tears down the cheek. The patient with symptomatic tearing may have a normal lacrimal drainage system overwhelmed by primary or secondary (reflex) hypersecretion or a drainage system that is anatomically compromised and unable to handle normal tear production. On the other hand, a patient with partial drainage obstruction may have a concomitant reduction in tear production and therefore be completely asymptomatic or may even suffer from symptomatic dry eye syndrome. Epiphora is determined by the balance between tear production and tear drainage, not by the absolute function or dysfunction of either one. The causes of lacrimal drainage problems can be divided into two categories: anatomic and functional. Anatomic obstruction refers to a mechanical or structural abnormality of the drainage system. The obstruction may be complete, such as punctal occlusion, canalicular blockage, or nasolacrimal duct fibrosis, or partial, caused by punctal stenosis, canalicular stenosis, or mechanical obstruction within the lacrimal sac (i.e., dacryolith or tumor). In patients with functional obstruction, epiphora results not from anatomic blockage but from a failure of lacrimal drainage physiology. This failure may be caused by anatomic deformity such as punctal eversion or other eyelid malpositions, but can also result from lacrimal pump inadequacy caused by weak orbicularis muscle action. It is helpful to determine whether the patient’s complaint is true epiphora or a “watery eye.” Detailed history-taking and careful examination will help direct the evaluation of a tearing eye. A host of clinical tests have been described, and the selection of appropriate tests will depend on the initial history and ophthalmic examination. 13-1-1 History-Taking. Any clinical evaluation should begin with a thorough history. A complaint of watery eye does not necessarily imply a lacrimal drainage problem.
Optic Nerve Sheath Decompression
Authors: Hwang Thomas N. , McCulley Timothy J.
Published: November 2020

Optic nerve sheath decompression (ONSD) or fenestration refers to a surgical technique that creates a window through the dural and arachnoid meningeal layers of the retrobulbar optic nerve sheath to release pressure on the optic nerve. ONSD for treatment of visual loss secondary to refractory papilledema was first described by DeWecker in 1872. Later that century, Carter and Müller published the second case series of optic nerve sheath fenestrations. However, despite these and several additional reports, the clinical benefit of performing this procedure was still questioned. In addition, alternative cerebrospinal shunting procedures were developed for patients with increased intracranial pressure. Renewed interest arose in 1964 when Hayreh demonstrated the effectiveness of ONSD in relieving experimental papilledema in rhesus monkeys. Various supporting clinical publications have since followed, starting with Smith, Hoyt, and Newton’s description in 1969 of relief of chronic papilledema by ONSD. Surgical intervention is considered for patients with progressive visual loss secondary to elevated intracranial pressure (ICP) in whom conservative management, such as medications (acetazolamide and furosemide) and weight control, has failed. Occasionally surgery is used primarily in patients whose visual function has already reached a critical level. Examples include patients in whom vision has declined to a disabling level in hopes that rapid papilledema resolution will result in some visual return. Surgery is also considered primarily in those with little remaining vision, in whom any further visual loss would carry substantial functional impact should conservative management fail. Once surgical intervention is deemed necessary, ONSD is one of several options. Cerebrospinal fluid (CSF) shunting in the form of ventricular–peritoneal (VP) or lumbar–peritoneal (LP) shunting can be considered. A deciding factor for some is the presence of headache, which is more effectively managed with VP or LP shunting. Comparative trials of ONSD and other CSF shunting procedures are lacking. Consequently, some medical centers opt for ONSD as the first-line surgical option, while others recommend alternative shunting procedures. At present, the only uniformly accepted therapeutic indication for ONSD is management of visual loss related to elevated ICP. The most common setting for ONSD is idiopathic intracranial hypertension.
Complications of the Anophthalmic Socket
Authors: McCann John D. , Lin Yang Chun Cheng
Published: November 2020

The anophthalmic socket is subject to four major deformities: enophthalmos, exposure, eyelid malposition, and socket contraction. Enophthalmos occurs when there is a lack of soft tissue volume, creating a sunken or hollow appearance. Exposure occurs when a previously placed orbital implant erodes through the ocular surface. Eyelid malposition occurs largely as a consequence of wearing of a prosthesis. Socket contraction occurs when there is insufficient ocular surface area and fornix depth to accommodate a mobile prosthesis. Understanding these disfigurements and their treatments is the goal of this chapter. Anopththalmic enophthalmos is an acquired condition that occurs when there is a lack of orbit volume after removal of the eye. In a typical case 6 mL of volume is lost with removal of the eye. An orbital implant will replace 2 to 4 mL of volume, and a prosthesis will replace 1 to 2 mL of volume. This leaves a volume deficit of 1 to 3 mL. This typical volume deficit can be exacerbated by fat and muscle atrophy secondary to surgery or antecedent trauma. In cases of eyes removed secondary to orbital trauma, unrepaired orbital fractures expand the bony orbit, further exacerbating the lack of orbital soft tissue. After removal of the eye the orbital implant and the inadequate volume of orbital soft tissue tend to settle toward the orbital floor, creating more of a volume deficit in the superior orbit. The orbital fat is somewhat liquid and much of the preaponeurotic fat in the upper eyelid flows posterior and inferior, creating the hollow appearance in the superior fornix of the anophthalmic socket. This deformity is referred to as the superior sulcus deformity and is present in some degree in the majority of anophthalmic sockets. 24-1-1 Diagnosis. History-taking should direct the ophthalmologist toward the cause of the patient’s anophthalmos. If the eye was lost to trauma, the possibility of orbital fractures expanding the orbital volume and exacerbating the condition should be considered. If the socket was radiated, the possibility of radiation-induced orbital soft tissue atrophy should be considered.
Chemical and Laser Resurfacing of the Eyelids and Face
Authors: Holds John B.
Published: November 2020

Chemical peels, mechanical abrasion, and more recently laser and electrosurgical devices are used to resurface eyelid and facial skin. The common feature in these techniques is the denaturation or removal of the skin surface. These techniques typically help to hide skin changes related to sun exposure and aging by evening the skin tone, decreasing dyschromia, and diminishing wrinkles. These techniques all require careful case selection and patient preparation with appropriate treatment and postoperative care. Recent interest has focused on less invasive therapy with techniques that leave the epithelium largely intact, shortening healing time and reducing the risk of complications. Aging and sun damage induce a number of changes in skin, including wrinkling, the development of muscle- or gravity-related folds, irregular pigment or dyschromia, and the growth of benign and malignant skin lesions. Scars from acne, trauma, or surgery can also be indications for skin resurfacing. Potential benefit in all of these techniques must be balanced against risks and expected healing time. A medical history must be obtained, looking for a history of immune dysfunction, prior acne, or a history of herpes simplex outbreaks. Prior treatment with radiation or isotretinoin (Accutane) may diminish the pilosebaceous units required for healing. Acne rosacea and cutaneous telangiectasia may be aggravated by skin resurfacing. Cutaneous history must focus on scarring tendencies such as keloid formation, skin type, and ancestry. In particular, one must determine the patient’s skin type, most commonly by assigning a Fitzpatrick’s skin type. Patients with skin type III require careful topical preparation for skin resurfacing treatment in most cases, and patients with skin type IV or higher are more prone to scarring and pigment issues and are not treated with medium depth to deep skin resurfacing techniques by most clinicians. Wrinkles may be graded by the Glogau classification scheme. This scale from “fine wrinkles” (type 1) to “only wrinkles” (type IV) will help to define the amount and type of treatment needed. These loose recommendations will generally hold true in determining effective therapy. The deeper and more invasive the treatment, the more important the role of skin preparation and prophylaxis.
Type 1 Diabetes
Authors: Hershey Tamara
Published: November 2020

Type 1 diabetes mellitus (T1DM; formerly known as juvenile-onset diabetes or insulin-dependent diabetes) is characterized by progressive loss of the insulinproducing β-cells in the pancreas. Insulin is necessary for the transport of glucose from the bloodstream to cells needing it for fuel; thus, untreated individuals with T1DM have excessive glucose in the blood (hyperglycemia) while the rest of their body essentially starves. Treatment is compensatory, consisting of exogenously administered insulin either through multiple daily injections or, increasingly, continuous infusion (with supplemental bolus doses) from an insulin pump. Type 1 diabetes mellitus has a recently estimated prevalence of 1.54 cases per 1,000 youth (<20 years of age), making it one of the most common chronic childhood diseases (Dabelea et al. 2007). In contrast, type 2 diabetes (characterized by insulin resistance) currently affects only 0.22 cases per 1,000 youth. Alarmingly, the incidence of both types of diabetes has increased dramatically in recent years (Dabelea et al. 2007; Vehik et al. 2007). Type 1 diabetes mellitus can be diagnosed at any age, but has a peak age of onset between 10 and 14 (Atkinson et al. 2001; Dabelea et al. 2007). Childhood onset of T1DM is associated with a significantly increased rate of complications and an overall reduced lifespan (Panzram 1984). Many of these complications are associated with chronic hyperglycemia, the default state of T1DM across the entire lifespan. Hyperglycemia has cumulative deleterious effects on many systems in the body, most notably the retina, kidney, peripheral nerves, and blood vessels. These complications can begin to develop during childhood and adolescence, albeit typically at subclinical levels (Chkhartishvili et al. 2002; Olsen et al. 2000; Riihimaa et al. 2001). In addition, severe hypoglycemia (low blood sugar), a complication of insulin treatment, is much more common during childhood than adulthood (Davis et al. 1997) and has acute neurological effects. However, the long-lasting effects of T1DM and its accompanying glycemic extremes on the central nervous system (CNS) are less well understood.
Cognitive and Behavioral Abnormalities Associated with Liver Disease and Wilson Disease
Authors: Frank Yitzchak
Published: November 2020

Liver diseases may be associated with neurological abnormalities, more commonly with central nervous system (CNS) dysfunction (Lewis and Howdle 2003; Lockwood 1995; Raskin and Rowland 1995; Steinberg and Frank 1993; Victor and Rothstein 1992). Consequently, cognitive and behavioral abnormalities are commonly present in patients with acute and chronic liver disease. Cognitive impairment may include impairments of memory, attention, and executive and motor functions, can be initially mild and then progress into overt hepatic encephalopathy (HE) (Collie 2005; O’Carroll 2007). Specific patterns of cognitive dysfunction have been investigated. Selective attention deficits and abnormalities of motor skills in the absence of impairment in general intellect, language, or visuospatial skills have been described, suggesting abnormalities of the basal ganglia as the pathophysiology for cognitive dysfunction in cirrhotic patients, at least in the early stages of HE (McCrea et al. 1996). We need to be aware of the fact that cognitive abnormalities may also be related to the etiology of liver disease (hepatitis C virus, Wilson disease, alcoholic liver disease [ADL]). Chronic alcoholism, a common etiology for liver disease in adults, may cause cognitive impairment of executive functions, including working memory, independent of the effect of the liver disease or impairment in the formation and retrieval of new memory in the case of Wernicke- Korsakoff disease. When ALD is present in addition to alcoholism, the result may be an increased severity of the same profile of deficits. Central and peripheral nervous system manifestations can be part of an infection with hepatitis virus. Encephalitis, myelitis, Guillain-Barré syndrome (GBS), and polymyositis are infrequent complications of hepatitis A and B (Peters 1989). Central nervous system manifestations of these diseases include encephalopathy, pyramidal signs, and myoclonus. Similarly, hepatitis C (HCV) virus infection may be associated with extrahepatic syndromes including those affecting the nervous system (Hilsabek 2003). Circulating immune complexes containing hepatitis B antigens have been detected in the serum and cerebrospinal fluid (CSF) of adult patients at the height of neurologic symptoms, but it is unclear whether this is due to intrathecal synthesis or whether it reflects blood–brain barrier dysfunction (Peters 1989).
Cognitive and Behavioral Manifestations in Turner Syndrome
Authors: Belger Aysenil , Hart Sarah J.
Published: November 2020

Turner Syndrome (TS) is a common genetic disorder that affects approximately 1 in 1,900 live female births. Like other sex chromosome abnormalities (SCAs), TS has high morbidity due to associated congenital abnormalities, neurodevelopmental disturbances, neurocognitive deficits, and social-behavioral problems. Many individuals with TS are not diagnosed. Those who are identified may be subject to inadequate care, bias, and discrimination because of a poor understanding of the condition among families, health care providers, and educators, especially regarding developmental profiles and outcomes. Turner syndrome results from an abnormal or missing second sex (i.e., X) chromosome, and by definition, affects only females. There is tremendous variability in the clinical presentations of individuals with TS that is likely due to the variable nature of the genetic abnormality. Approximately 50% of girls with TS have a 45X karyotype (Savendahl and Davenport 2000; Soriano-Guillen et al. 2005; Sybert and McCauley 2004), with the remainder having either a structural abnormality or mosaicism involving the X chromosome. Structural changes of the X chromosome include deletions, breakage of both arms to form a ring chromosome, or breakage and exchange in the X centromere region to form an isochromosome. Common mosaic patterns include 45,X/46,XX, 45,X/46,X,i(X), and 45, X/46,XY (Table 19.1). Correlations of clinical phenotype with cytogenetic data are further complicated by the wide range of structural abnormalities, as well as by mosaicism, differences in X-inactivation patterns, and the presence of abnormal recessive genes (Ogata and Matsuo 1995). Girls with 45X karyotype tend to be most severely affected, and there is less variability within this group than in the population as a whole. Many of the clinical manifestations of TS can be understood in the context of reduced expression of genes on the X chromosome (Neely 1994; Zinn and Ross 1998; Zinn et al. 1998). In normal females, one X chromosome is inactivated; however, the process is not complete. Genes on the X-chromosome that are not inactivated, so-called pseudoautosomal genes, are present in a cluster near the tip of the short arm and scattered elsewhere.
The Dystrophinopathies
Authors: Hinton Veronica J.
Published: November 2020

The dystrophinopathies, including Duchenne and Becker muscular dystrophies, are X-linked, developmental neuromuscular disorders. The dystrophinopathies are so named because of their effect on the production of the protein dystrophin, and are known primarily as muscle diseases in males that present with progressive weakness that is eventually fatal. To date, there is no cure for the dystrophinopathies, and treatment focuses on slowing the disease progression. Medical management is complex and multifaceted. It includes care for neuromuscular, orthopedic, rehabilitative, nutritional, respiratory, cardiac, gastrointestinal, psychological, and palliative aspects of the disease. The devastating physical toll of the diseases is well known. In contrast, the associated cognitive and behavioral abnormalities are less familiar to most clinicians. Nonetheless, the cognitive and behavioral attributes of the dystrophinopathies impact on the affected individual’s and his family’s functioning in far-ranging ways. More importantly, identifying any associated cognitive and behavioral abnormalities early, and providing appropriate interventions, can contribute substantially to an affected individual’s quality of life. The dystrophinopathies are the most common neuromuscular diseases of childhood, affect all ethnic groups, and have an estimated overall prevalence of 63 per million (Emery 1991; Emery 1992). Positive diagnosis for the Duchenne muscular dystrophy (DMD, the more severe form) is based on the following criteria: (a) male; (b) onset of weakness before age 5; (c) initial proximal muscle weakness; (d) muscle hypertrophy, most prominent in the calves; (e) elevated creatine kinase activity of at least 10 times above the upper limit of normal; and either (f) positive histopathological confirmation by muscle biopsy or (g) molecular characterization of a mutation within the gene for dystrophin. Approximately 1 in 3,500 live male births meet these criteria (Emery 1992). The diagnosis of Becker muscular dystrophy (BMD, the less severe form) is clinically determined by those children who remain walking at age 12. Individuals with BMD have a slower course and considerably longer lifespan than those with DMD. Natural history studies have been conducted to characterize the course of the disease. The Clinical Investigation of Duchenne Dystrophy group (CIDD) followed more than 200 individuals affected with DMD for more than 10 years (Brooke et al. 1983; Hyser et al. 1987; Mendell et al. 1987).
How Does ECT Work?
Authors: Fink MD Max
Published: November 2020

The major puzzle in ECT is its mechanism of action. How do seizures, which can be dangerous and damaging when they occur spontaneously, change a dysfunctional brain into one that performs normally? Why do repeated epileptic seizures relieve psychiatric disorders? The originator of the therapy, Ladislas Meduna, believed in a biological antagonism between mental illness and seizures, an antagonism we no longer consider credible. But though we may smile at this belief, we acknowledge that it led Meduna to devise methods to induce seizures safely, select patients who were likely to benefit, develop a plan for a successful course of treatments, demonstrate the safety of inducing seizures, evaluate the merits and risks of seizures as treatment, and convince others to continue his work. His observations have been repeatedly verified, leaving little doubt about the effectiveness of ECT in treating mental illnesses. We know a great deal about the essential features of a successful course of ECT. The generalized brain seizure is the central therapeutic event. The biochemical and physiological consequences of the seizure are the basis for the behavioral effects; neither anesthesia nor electric current alone is useful, nor, except rarely, is a single seizure. To be of benefit, seizures must be repeated two or three times a week for many weeks. The more recent the mood, thought, or movement disorder, the more fully it can be relieved. Illnesses involving lifelong problems, character pathology, neuroses, and the mood disorders secondary to the abuse of drugs are not amenable to this treatment. We know how to avoid the risks of anoxia, unmodified convulsions, and prolonged seizures, and we recognize that these aspects of the treatment course do not explain how ECT works. Two aspects of the brain seizure have been extensively studied. The EEG records electrical activity of the brain under electrodes that are symmetrically placed over the scalp. Immediately after the stimulus, the “seizure” EEG is recorded on a moving strip. The electrical waves show a sharp buildup of frequencies and amplitudes, then the frequencies slow, mixtures of slow brain waves and sharp spike-like waves appear, with ever higher amplitudes and slower waves in runs and bursts.
Formatting Citations and References
Authors: Robinson Marin S , Stoller Fredricka L , Constanza-Robinson Molly , Jones James K
Published: November 2020

In this chapter, we introduce you to formatting conventions for citations and references. Writers are obligated to cite others’ works that have significantly influenced or are relevant to their own work. It goes without saying that to include another’s original ideas without proper acknowledgment is plagiarism. Consequently, this stage of the writing process is critical both professionally and ethically. Although citations and references are inextricably linked, for clarity we deal with them separately. By the end of the chapter, you will be able to do the following: ■ Know what information should be cited ■ Know what information need not be cited ■ Use in-text citations appropriately ■ Recognize different reference formats (numerical and alphabetical) ■ Determine the appropriate reference format for your work Two Citing on Your Own tasks will guide you in preparing proper citations and references as you do the following: 17A Finalize citations 17B Compile and format references The seriousness of properly compiling and formatting citations and references is predictably emphasized in Information for Authors documents. The excerpts below serve as vital reminders of the importance of checking relevant guidelines before finalizing citations and references in your written work: Authors should be judicious in citing the literature; unnecessarily long lists of references should be avoided. (Author Information, J. Org. Chem. 2007, 72, 16A) The accuracy and completeness of the references are the authors’ responsibility. (Authors’ Guide, Anal. Chem. 2007, 79, 390 Avoid references to works that have not been peer-reviewed. (Instructions to Authors, Environ. Sci. Technol. 2007, 30) The citation of references in text . . . varies widely from journal to journal and publisher to publisher. . . . Authors are encouraged to check the author guidelines for a specific publication to find information on citing references. (The ACS Style Guide: Coghill and Garson, 2006) Most authors attend to citations and references when their work is nearly complete; useful reminders may be inserted into the text as they write—such as “cite Kopinski here” or “add ref”—but properly formatted citations and references are often added in the last stages of writing.
The Rough Topography of Human Health
Authors: De Blij Harm
Published: November 2020

If we made a map of the world showing locales with prevailing good public health as mountains and areas with poor health as valleys, the resulting global topography would look rough indeed. The unequal distribution of health and well-being across the world is matched by inequities of health within individual countries, even inside regions and provinces. Whatever the index, from nutrition to life expectancy, from infectious disease to infant mortality, the geography of health displays regional variations that add a crucial criterion to the composite power of place. If it is obvious that the medical world is not flat, the question is whether the landscape of human health is flattening out. Certainly health is a matter of natural environment, cultural tradition, genetic predisposition, and other factors, but power has a lot to do with it as well. In general, the poorest and weakest on the planet are also the sickest. The fact that, in the twenty-first century, 300 million people suffer from malaria and more than one million (mostly children) die every year has as much to do with figure 1.1 as it does with tropical environments and adapting vectors. The rich and medically capable countries of the core never sustained a coordinated campaign to defeat (or at least contain) malaria, a disease of the periphery of much lower priority than maladies of the mid-latitudes. Medical research in the United States and elsewhere did produce treatments for victims of the deadly HIV/AIDS pandemic that has taken more than 25 million lives over the past three decades, most of them in Subsaharan Africa, but those costly remedies are reaching far too few sufferers outside the global core. The obvious link between persistent poverty and endemic disease, so evident from virtually any medical-geographic map of the global periphery, was one of the key factors that spurred all 191 members of the United Nations in 2002 to sign the UN Millennium Declaration, among whose eight Development Goals are the reduction of child mortality, the eradication of extreme poverty and associated hunger, and the defeat of major diseases, including malaria and HIV/AIDS.
Lowering the Barriers
Authors: De Blij Harm
Published: November 2020

Becoming conscious of one’s cultural and physical environments early in life involves fast-developing recognition of circumstances malleable and immutable. By the time we are about six years old, our brain is about as big as it will be for the duration, but its maturation goes on for many years more. The language-learning ability of young children, the subject of numerous studies and much speculation, undoubtedly connects this process; youngsters are able to recollect facts and vocabularies but cannot match adults or even adolescents in conceptualizing context or relationships. While we quickly learn to use words to gain immediate objectives such as nourishment or affection, it takes much longer to begin forming an understanding of our place and its (apparently) fixed attributes. Thus our perception of place changes over time, as do the opportunities to counter its formative impress. Bilingualism and multilingualism already are a key to upward mobility and will be more so in the future; exposing children in their earliest years of learning to a language other than the mother tongue will endow them with potentially immense advantages. Religious fanaticism is intensifying in many parts of the world; protecting children against it in their early years gives them the chance to develop their contextual abilities before being exposed to it. Religious leaders of all faiths would do well to consider the divine potential of pronouncements that assert the superiority of their particular beliefs and rituals over others. Pope Benedict in the spring of 2007 declared that Roman Catholicism afforded the only true route to salvation and that all other (Christian) approaches are “defective,” a proclamation Christianity and the world could have done without. Drilling into children that “there is no god but Allah” closes young minds to the religious convergence that should be the hope of all believers. It may not be absolutely true that “religion poisons everything,” the subtitle of an angry book on the topic, but religious males in medieval outfits do misuse their powers to erect barriers that last lifetimes. The power of place defines an aggregate of circumstances and conditions ranging from cultural traditions to natural phenomena, into which we are born, with which we cope, and from which we derive our own multiple identities.
Liquids and Solids
Authors: Oriakhi Christopher O.
Published: November 2020

The atoms or molecules in a liquid have enough kinetic energy to partially overcome the forces of attraction between them. Therefore, they are in constant random motion (as in a gas) but they are still relatively close together. However, they are not as tightly packed, or as well ordered, as in a solid. There is not as much free space in a liquid as in a gas. The atoms or molecules may aggregate together to form chains or rings that readily move relative to one another; this gives a liquid its fluid (flow) properties. Liquids generally occur as compounds. For example, water, ethanol, and carbon tetrachloride are liquids at room temperature. However, a few elements are also liquids at room temperature: bromine, cesium, gallium, mercury, and rubidium. A liquid is characterized by the following physical properties: boiling point and freezing point, density, compressibility, surface tension, and viscosity. These properties of a liquid are greatly influenced by the strength of its intermolecular forces. In summary: • Liquids have definite volume but no definite shape. They take on the shape of their containers. • Liquids are characterized by low compressibility, low rigidity, and high density relative to gases. • Liquids diffuse through other liquids. • Liquids can vaporize into the space above them and produce a vapor pressure. Polar molecules possess an electric dipole moment, μ, defined as the product of the magnitude of the partial charges Q+ and Q− on the molecule and the distance r separating the charges. In mathematical terms, it is given by the equation: μ = Qr The unit for μ is debyes (D), and 1 D = 3.336×10−30 coulomb meter (C-m). No interatomic bonds are completely ionic. Knowing the dipole moment of a compound, though, lets us differentiate ionic from covalent bonds by calculating the percent ionic character for the bonds. The percent ionic character of a bond is found by comparing the measured dipole moment of the molecule of the type A−B with the calculated dipole moment for the 100% ionized compound A+B−.
Ideal Solutions and Colligative Properties
Authors: Oriakhi Christopher O.
Published: November 2020

Colligative properties of solutions are those that depend only on the number of solute particles (molecules or ions) in the solution rather than on their chemical or physical properties. The colligative properties that can be measured experimentally include: • Vapor pressure depression • Boiling point elevation • Freezing point depression • Osmotic pressure Noncolligative properties, on the other hand, depend on the identity of the dissolved species and the solvent. Examples include solubility, surface tension, and viscosity. The addition of a solute to a solvent typically causes the vapor pressure of the solvent (above the resulting solution) to be lower than the vapor pressure above the pure solvent. As the concentration of the solute in the solution changes, so does the vapor pressure of the solvent above a solution. The vapor pressure of a solution of a nonvolatile solute is always lower than that of the pure solvent. For example, an aqueous solution of NaCl has a lower vapor pressure than pure water at the same temperature. The addition of solute to a pure solvent depresses the vapor pressure of the solvent. This observation, first made by Raoult, is now commonly known as Raoult’s law. The law states that the lowering of vapor pressure of a solution containing non-volatile solute is proportional to the mole fraction of the solute.
Chemical Kinetics
Authors: Oriakhi Christopher O.
Published: November 2020

Chemical kinetics is the aspect of chemistry that deals with the speed or rate of chemical reactions and the mechanisms by which they occur. The rate of a chemical reaction is a measure of how fast the reaction occurs, and it is defined as the change in the amount or concentration of a reactant or product per unit time. The mechanism of a reaction is the series of steps or processes through which it occurs. Most experimental techniques for determining reaction rates involve measuring of the rate of disappearance of a reactant, or the rate of appearance of a product. For a reaction in which the reactant Y is converted to some products: Rate = Concentration of Y at time t2 −Concentration of Y at time t1/t2 −t1 Rate = Δ [Y]/ Δt where [Y] indicates the molar concentration of the reactant of interest, and Δ refers to a change in the given amount. Rate for a reactant, by this definition, is a negative number. For a product, it is positive. The value of the rate at a particular time is known as the instantaneous rate and will be different from the average rate. Its value can be obtained from the plot of concentration (mol/L) vs. time (s) as the slope of a line tangent to the curve at a given point. Consider the following kinetic data for the decomposition of N2O5 to gaseous NO2 and O2 at 40°C (see table 16-3). A plot of [N2O5] vs. time is shown in figure 16-2. From this curve, the instantaneous rate of reaction at any time t can be obtained from the slope of the tangent to the curve. This corresponds to the value of Δ [N2O5]/ Δt for the tangent at a given instant. The instantaneous rate at the beginning of the reaction (t =0) is known as the initial rate.
Solubility and Complex-Ion Equilibria
Authors: Oriakhi Christopher O.
Published: November 2020

Solubility equilibria are heterogeneous equilibria that describe the dissolution and precipitation of slightly soluble ionic compounds. Examples are commonly encountered in many chemical and biological processes. This chapter deals with the application of chemical equilibrium to heterogeneous systems involving saturated solutions of slightly soluble ionic compounds. When a slightly soluble salt is dissolved in water, it eventually reaches a point of saturation where equilibrium is established between the undissolved salt and its solution.
Chemical Thermodynamics
Authors: Oriakhi Christopher O.
Published: November 2020

Chemical thermodynamics is the study of the energy changes and transfers associated with chemical and physical transformations. Energy is the ability to do work or to transfer heat. A spontaneous process is one that can occur on its own without any external influence. A spontaneous process always moves a system in the direction of equilibrium. When a process or reaction cannot occur under the prescribed conditions, it is nonspontaneous. The reverse of a spontaneous process or reaction is always nonspontaneous. Heat (q) is the energy transferred between a system and its surroundings due to a temperature difference. Work (w) is the energy change when a force (F) moves an object through a distance (d). Thus. . . W = F ×d. . . . A system is a specified part of the universe (e.g., a sample or a reaction mixture we are studying). Everything outside the system is referred to as the surroundings. The universe is the system plus the surroundings. A state function is a thermodynamic quantity that defines the present state or condition of the system. Changes in state function quantities are independent of the path (or process) used to arrive at the final state from the initial state. Examples of state functions include enthalpy change (ΔH), entropy change, (ΔS) and free energy change, (ΔG). The internal energy of a system is the sum of the kinetic and potential energies of the particles making up the system. While it is not possible to determine the absolute internal energy of a system, we can easily measure changes in internal energy (which correspond to energy given off or absorbed by the system). The change in internal energy, . . . ΔE, is: ΔE = Efinal –Einitial. . . . The first law of thermodynamics, also called the law of conservation of energy, states that the total amount of energy in the universe is constant, that is, energy can neither be created nor destroyed. It can only be converted from one form into another. In mathematical terms, the law states that the change in internal energy of a system, ΔE, equals q+w. That is,. . . ΔE = q+w. . . In other words, the change in E is equal to the heat absorbed (or emitted) by the system, plus work done on (or by) the system.
Radioactivity and Nuclear Reactions
Authors: Oriakhi Christopher O.
Published: November 2020

Nuclide: an atom containing a specified number of protons and neutrons in its nucleus—in other words, any particular atom under discussion. Unstable nuclide: one that will spontaneously disintegrate or emit radiation, thus giving off energy and altering to some new form (often another element). The new form may also be unstable; often it will be stable, that is, with no tendency to disintegrate. Unstable nuclides are also referred to as radioactive. Radioactivity: the spontaneous emission of radiation by elements with unstable nuclei. Radionuclide: a radioactive (that is, unstable) nuclide. Radioisotope: another more commonly seen term for radionuclide. Radioactive decay: the process whereby a radionuclide is converted to another form (usually another element) by emitting radiation. Parent nuclide: a nuclide undergoing radioactive decay. Daughter nuclide: the nuclide produced when a parent nuclide decays. Activity: the rate at which a sample of the material decays, usually expressed as the number of disintegrations per unit time. Naturally radioactive elements decay spontaneously by emitting alpha particles, beta particles, and gamma radiation. Other elements can be induced to decay by bombarding them with high-energy particles; this is known as artificial radioactivity. Like chemical reactions, equations representing nuclear reactions must be balanced. However, the method for balancing nuclear equations differs from that used for chemical equations. To balance a nuclear equation, the sum of the atomic numbers or particle charges (subscripts) and the sum of the mass numbers (superscripts) on both sides of the equation must be equal. When a nucleus undergoes alpha decay, it emits a particle that is identical to a helium nucleus, with an atomic number of 2 and a mass number of 4. Since the emission of an alpha particle from the nucleus results in a loss of 2 protons and 2 neutrons, when writing a nuclear reaction involving an alpha decay, subtract 4 from the mass number and 2 from the atomic number.
Higher Education under Attack
Authors: Fish Stanley
Published: November 2020

So I return in the end to my one-note song: if academics did only the job they are trained and paid to do— introduce students to disciplinary materials and equip them with the necessary analytic skills—criticism of the kind Maloney mounts would have no object, and the various watch-dog groups headed by David Horowitz, Daniel Pipes, and others would have to close shop. But even if this day were to arrive, the academy would not be home free because there would still be the problem I have alluded to but not fully addressed—the problem of money. Who is going to pay for the purified academic enterprise I celebrate in these pages? The unhappy fact is that the more my fellow academics obey the imperative always to academicize, the less they will have a claim to a skeptical public’s support. How do you sell to legislators, governors, trustees, donors, newspapers, etc., an academy that marches to its own drummer, an academy that asks of the subjects that petition for entry only that they be interesting, an academy unconcerned with the public yield of its activities, an academy that puts at the center of its operations the asking of questions for their own sake? How, that is, do you justify the enterprise? As I have already pointed out, you can’t, in part because the demand for justification never comes from the inside. The person who asks you to justify what you do is not saying, “tell me why you value the activity,” but “convince me that I should,” and if you respond in the spirit of that request, you will have exchanged your values for those of your inquisitor. It may seem paradoxical to say so, but any justification of the academy is always a denigration of it. The only honest thing to do when someone from the outside asks, “what use is this venture anyway?” is to answer “none whatsoever,” if by “use” is meant (as it always will be) of use to those with no investment in the obsessions internal to the profession.
Specific Phobias
Authors: Starcevic, MD, PhD Vladan
Published: November 2020

Specific phobias (also referred to as simple phobias and isolated phobias) represent a heterogeneous group of disorders characterized by excessive and/or irrational fear of one of relatively few and usually related objects, situations, places, phenomena, or activities (phobic stimuli). The phobic stimuli are either avoided or endured with intense anxiety or discomfort. People with specific phobias are aware that their fear is unreasonable, but this does not diminish the intensity of the fear. Rather, they are quite distressed about being afraid or feel handicapped by their phobia. Specific phobias are frequently encountered in the general population, but they are relatively uncommon in the clinical setting. Most phobias have a remarkable tendency to persist, prompting an assumption that they cannot be easily extinguished because of their ‘‘purpose’’ to protect against danger. Specific phobias are deceptively simple, as they are easy to describe and recognize but often difficult to understand. There are several conceptual problems and a number of issues associated with specific phobias:… 1. Where are the boundaries of specific phobias? How can we develop better criteria on the basis of which specific phobia could be distinguished as a psychiatric disorder from fears and avoidance considered to be within the realm of ‘‘normality?’’ 2. How can specific phobias be taken seriously by both the sufferers and clinicians? 3. In view of the considerable differences between various types of specific phobias, should they continue to be grouped together? 4. Should specific phobias be grouped on the basis of whether they are driven by fear or disgust? 5. In view of its unique features, should the blood-injection-injury type of specific phobia be given a separate psychopathological, diagnostic, and nosological status? 6. Considering a significant overlap between situational phobias and agoraphobia, should they be grouped together, along a hypothetical situational phobia/agoraphobia spectrum? 7. What is the relationship between specific phobias and other psychopathology? Are they relatively isolated from other disorders, both cross-sectionally and longitudinally, or should they more appropriately be conceptualized as a predisposition to or a risk factor for some psychiatric conditions? 8. How specific are pathways that lead to specific phobias? 9. Has the dominant treatment model for specific phobias, based on exposure therapy, exhausted its potential? Is the tendency for specific phobias to persist adequately addressed by treatments derived from learning theory?
Staying Healthy
Authors: Compton Michael T , Broussard Beth
Published: November 2020

To move towards recovery after a first episode of psychosis, patients must focus on both their mental and physical health. People with a serious mental illness are usually less healthy than those without such an illness. This may be because of the illness itself, fewer opportunities for health care, or unwanted effects of the medicines taken to treat mental illnesses. People with a long-lasting mental illness sometimes also deal with other issues, such as cigarette smoking, drug abuse, unhealthy eating habits, little exercise, and having few relationships with others. Even though it can be difficult at times, living a healthy lifestyle is necessary for patients to feel better and move towards recovery. In this chapter, we discuss problems sometimes faced by people with psychosis and ways to deal with and overcome these issues. Specifically, this chapter focuses on the importance of not smoking cigarettes, staying away from alcohol and drugs, having a healthy diet, getting plenty of exercise, and having good social support from family and friends. One problem sometimes faced by people with psychosis is cigarette smoking. About one in five people in the general population in the United States (about 21%) smoke cigarettes. Fortunately, this percentage is now decreasing because of the growing awareness of the health risks posed by cigarette smoking. However, a large percentage of people with psychosis smoke. For example, most people with schizophrenia (between 50% and 90%) smoke cigarettes. What’s more, this percentage has not decreased in recent years. People with psychotic disorders also have smoking behaviors that can cause even greater harm. Some of these behaviors include smoking heavily—up to two or three packs a day—and smoking cigarettes down to the filter where the greatest concentration of nicotine is. Why are people with psychosis so likely to smoke, and to smoke so heavily? Most researchers believe that it is because of the relationship between cigarette smoking, nicotine, and the symptoms of psychosis (see Chapter 2 on What Are the Symptoms of Psychosis?). Nicotine is a drug that affects anyone who uses it. In most people, nicotine may slightly improve attention and memory.
Promoting Recovery
Authors: Compton Michael T , Broussard Beth
Published: November 2020

When someone recovers from a physical illness, others often think of him or her as cured. But what about in the field of mental health? Presently, there is no cure for some mental illnesses that cause an episode of psychosis, such as schizophrenia. So, what does it mean for a person with a mental illness like this to recover? One way of thinking about recovery is that instead of people recovering from a mental illness, they recover despite the mental illness. In other words, people can develop meaningful activities and relationships while learning to manage and live with their mental illness. Recovery is different from remission. Remission means that the major symptoms, usually positive symptoms like hallucinations and delusions, are no longer active. The goals of remission and recovery go hand in hand. Aiming for remission using medicines and psychosocial treatments is important because recovery is easier when symptoms are under control. But, recovery is a much broader concept, pertaining to one’s life goals, rather than to symptom control. Some people experiencing psychosis may appear to recover completely. Others may require ongoing work to improve to the greatest possible level of recovery despite having a long-term illness. The recovery movement is a recent change in thinking about treatment and living with a serious mental illness. Before, to most people, the word recovery meant that a patient was symptom-free or improved to some point set by medical professionals. In the new way of thinking, recovery begins by focusing on the person’s thoughts and goals about his or her life rather than his or her illness, then moves into helping the individual figure out how he or she fits into his or her own community and larger society. Individuals themselves decide on their personal goals for treatment and recovery instead of mental health professionals deciding for them. Recovery involves an individual reaching his or her goals for independent living, employment, social relationships, and community participation. People with mental illnesses want to be citizens, to participate in shared relationships, and to give something to their communities. Increasing an individual’s social skills and ability to function in society is a major part of the recovery process.