bluuebunny/crossref_metadata_2025 huggingface dataset:
The Path Forward
Authors: Crane Hewitt , Kinderman Edwin , Malhotra Ripudaman
Published: November 2020

In this book we reviewed the course of energy consumption over the ages and projected the level of consumption through 2050. To facilitate the discussion, we introduced a new unit of energy—a cubic mile of oil equivalent, or CMO—that enables description of global energy flows in terms and numbers that are immediately comprehensible. We surveyed the various sources of energy in current use, established the quantities used, and projected our future needs on a global basis. While for much of our history the availability of energy has played an important role in determining the potentials and abilities of humans, in recent times energy has become much more important because resources are coming under strain. Greater energy use is beginning to influence our environment more strongly than ever before. A characteristic of global energy supply systems is the slowness with which they can shift. The slowness is a consequence of several factors. The size of the incumbent technologies and the advantage that they have in terms of learned improvements, economies of scale, and delivery infrastructure, play an important role in the rate at which new technologies are adopted. New technologies are often more expensive simply because cost reductions occur with experience, and it takes time for something new to penetrate the markets and build an experience base. Government subsidies and research and development (R&D) investments can help break this vicious cycle, but in the end the technologies have to deliver value to the customers before they can be adopted widely. There are also limited numbers of manufacturing and delivery systems in place for new technologies. Because basic energy supplies adapt slowly to change—as do most technologies—while energy demand grows more rapidly with population and income, we must act now to bring new supplies and new patterns of energy demand into play to meet the projected global energy demands of mid 21st century. Time is of the essence! Abundant energy has become an essential part of modern life, and we cannot go without it if we wish to retain even a small fraction of our current civilization.
Good News: Research and Medicinal Chemists Making a Difference
Authors: Griep Mark A. , Mikasen Marjorie L.
Published: November 2020

Stories of people doing their jobs well, treating each other with respect, and trying to make the world a better place are all examples of “good news.” Such stories don’t generate many website hits, nor do they bring people into the theaters. Instead, it seems readers and movie viewers would rather have the double pleasure of learning about bad behavior and its comeuppance. Five movies in this chapter overcome this problem; they are based on true stories. The advantage of such stories is the sympathy viewers feel as they appreciate the adversities the chemist has overcome to make their celebrated findings. For instance, in the documentary Me & Isaac Newton, which explores the motivations of seven scientists, pharmaceutical chemist Gertrude Elion is warm and charming as she describes why she decided to become a chemist. When she later describes her struggles to enter graduate school and then get a job as a chemist, the viewer is struck by her matter-of-fact, water-under-the-bridge tone. This all happened before she understood there was a climate of active discrimination against women that had nothing to do with their drive or abilities. Still later, she says the ultimate reward for all her work comes when someone thanks her for having developed the drug that cured a loved one. The disadvantage of using true stories is the need to create dramatic tension. The important moments in people’s lives rarely coincide with obvious indications that “this is the moment when everything fell into place,” whereas a movie’s linear narrative has to make that point clear to the audience. Another problem for moviemakers is that most people just aren’t very curious about the origins of everyday things. This is a challenge because very few chemicals cause the imagination to soar (unless you are a chemist), which may explain why all five movies based on true stories are about medicinal chemistry, which can be seen as the external evidence of the chemist’s desire to do good things for other people. Fictional movie chemists are less likely to develop medicines. Like the chemistry professors in chapter 8, they tend to develop chemical products for more selfish reasons.
Retinal Detachment
Authors: Brinton Daniel A. , Wilkinson Charles P.
Published: November 2020

Retinal Detachment: Principles and Practice provides a historical review of current information on the diagnosis and treatment of retinal detachment. It is intended as both an introduction for graduate students in ophthalmology and a concise review or reference for practicing ophthalmologists. The volume defines the types of retinal detachments, their classifications and causes, and covers preoperative examination, preoperative management, prophylactic procedures, surgery, complications of surgery, and results of reattachment surgery. It also includes a historical introduction, suggested readings at the end of each chapter, and the classic article 'The Technique of Binocular Indirect Ophthalmoscopy,' by Morten L. Rosenthal.
History of Surgery for Retinal Detachment
Authors: Brinton Daniel A. , Wilkinson Charles P.
Published: November 2020

The evolution of the retinal reattachment operation is one of the most remarkable chapters in the history of ophthalmology. Gonin’s operation for repair of the detached retina ranks with Daviel’s cataract extraction, von Graefe’s peripheral iridectomy, and Machemer’s vitrectomy as one of history’s most important surgical treatments for blinding eye diseases. The entity of retinal detachment was recognized early in the eighteenth century by de Saint-Yves, who reported the gross pathologic examination of an eye with a detached retina. The first clinical description did not appear until almost a century later, in 1817, when Beer detected a retinal detachment without the benefit of an ophthalmoscope. Von Helmholtz’s invention of the direct ophthalmoscope in 1851 was a giant step forward in diagnostic technique, and a rapid succession of ophthalmoscopic observations of retinal detachments soon followed. In the same year, Coccius reported the ophthalmoscopic detection of breaks in the detached retina. Von Graefe theorized in 1858 that retinal detachment was caused by a serous effusion from the choroid into the subretinal space. When he observed a retinal break, he assumed that it was secondary to the detachment and represented the eye’s attempt to cure itself. Supposing that the development of a break would allow the subretinal fluid to pass from the subretinal space into the vitreous cavity, he attempted unsuccessfully to treat detachments with deliberate incision of the retina. Girard-Teulon invented the reflecting binocular indirect ophthalmoscope in 1861. This potentially important contribution was generally overlooked by the profession, and more than 80 years transpired before Schepens developed the selfilluminating binocular indirect ophthalmoscope. In 1869 Iwanoff described the entity of posterior vitreous detachment, which is now recognized as a prerequisite to the development of most retinal detachments. The following year de Wecker suggested that retinal breaks cause detachment due to the resultant passage of vitreous fluid through the break into the subretinal space. Unfortunately, his accurate interpretation was not generally accepted. In 1882 Leber reported his observation of retinal breaks in 14 of 27 retinal detachments, and he correctly inferred the role of vitreous traction in the pathogenesis of breaks. Unfortunately, he later altered this opinion.
Evaluation and Management
Authors: Brinton Daniel A. , Wilkinson Charles P.
Published: November 2020

Evaluation of a patient for retinal detachment includes a thorough history and a complete ocular exam, including measurement of visual acuity, external examination, ocular motility testing, testing of pupillary reactions, anterior-segment biomicroscopy, tonometry, and binocular indirect ophthalmoscopy with scleral depression. Posterior-segment biomicroscopy, perimetry, and ultrasonography are also sometimes required. Rhegmatogenous retinal detachment is a diagnosis generally made by clinical examination of the retina alone, but a full history, ocular examination, and sometimes selected ancillary tests are also important parts of the evaluation (Figure 4–1). The symptoms of retinal detachment include fl ashes of light, new floaters, visual Field defect, decreased visual acuity, metamorphopsia, and rarely, defective color vision. The perception of light fl ashes, or photopsia, is due to the production of phosphenes by pathophysiologic stimulation of the retina. The retina is activated by light but is also capable of responding to mechanical disturbances. In fact, the most common cause of light fl ashes is posterior vitreous detachment. As the vitreous separates from the retinal surface, the retina is disturbed mechanically, stimulating a sensation of light. This perception is more marked if there are focal vitreoretinal adhesions. Generally, vitreous separation is benign and may almost be regarded as normal in the senescent eye. In approximately 12% of symptomatic posterior vitreous detachments, however, a careful search of the periphery reveals a tear of the retina. If the fl ashes are associated with floaters, it is wise to assume that a retinal tear exists, until proved otherwise. These symptoms demand a prompt and careful examination of the periphery with binocular indirect ophthalmoscopy and scleral indentation. The patient’s localization of the photopsia is of little value in predicting the location of the vitreoretinal pathology. If no breaks are evident in the first examination after symptomatic vitreous detachment, they rarely appear at a later date. If there is no associated hemorrhage or other pathologic condition, the patient needs counseling only. However, if pigment or blood is detected in the vitreous, a follow-up examination is often required. It is prudent to forewarn patients about the symptoms of retinal detachment. Flashes alone or floaters alone are less significant than if they occur together, in which case they are more likely to be associated with a retinal break.
The Sampling Theorem
Authors: Marks II Robert J
Published: November 2020

Much of that which is ordinal is modelled as analog. Most computational engines, on the other hand, are digital. Transforming from analog to digital is straightforward: we simply sample. Regaining the original signal from these samples or assessing the information lost in the sampling process are the fundamental questions addressed by sampling and interpolation theory. This chapter deals with understanding, generalizing and extending the cardinal series of Shannon sampling theory. The fundamental form of this series states, remarkably, that a bandlimited signal is uniquely specified by its sufficiently close equally spaced samples. The cardinal series has many names, including the Whittaker-Shannon sampling theorem [514], the Whittaker-Shannon-Kotelnikov sampling theorem [679], and the Whittaker- Shannon-Kotelnikov-Kramer sampling theorem [679]. For brevity, we will use the terms sampling theorem and cardinal series. If a signal has finite energy, the minimum sampling rate is equal to two samples per period of the highest frequency component of the signal. Specifically, if the highest frequency component of the signal is B hertz, then the signal, x(t), can be recovered from the samples by The frequency B is also referred to as the signal’s bandwidth and, if B is finite, x(t) is said to be bandlimited [1283].
Management of Ectropion and Floppy Eyelids
Authors: Marx Douglas P. , Yen Michael T.
Published: November 2020

Ectropion is defined as an eversion of the upper or lower eyelid away from the globe. Classes of ectropion include involutional, cicatricial, paralytic, and mechanical. Ectropic eyelids develop from horizontal eyelid laxity, medial canthal tendon laxity, vertical skin tightness, neuromuscular dysfunction, and lower eyelid retractor disinsertion. Ocular complications associated with ectropic eyelids include corneal exposure and scarring, conjunctivitis, ocular discomfort, photophobia, epiphora, and decreased vision. The entire face and eye should be carefully examined when a patient presents with ectropion. A systemic approach enables the physician to more fully understand the underlying disease process and best therapeutic approach. Ectropion can be quantified by pulling the central portion of the lid anteriorly and measuring the number of millimeters from the anterior cornea to the apex of the eyelid. Ectropion etiology can be elucidated by evaluating for horizontal eyelid laxity, orbicularis dysfunction, vertical skin tightness, and lower eyelid retractors disinsertion. Horizontal eyelid laxity is typically a result of lateral or medial canthal tendon stretching. Laxity of the canthal tendons produces a redundancy in the eyelid tissues, resulting in ectropion, often referred to as an involutional ectropion. Lateral canthal tendon status can be determined by gently pulling the eyelid nasally. The inferior crus of the tendon can then be palpated to evaluate for dehiscence. The medial canthal tendon can be evaluated by pulling laterally and noting the displacement of the inferior punctum. The severity of canthal tendon laxity should be quantified prior to any surgical intervention. 8-2-1 Lateral Canthal Tendon Laxity and the Lateral Tarsal Strip Procedure. Although a variety of methods have been advocated for treatment of lateral canthal tendon laxity, we prefer the lateral tarsal strip, introduced by Anderson. This procedure corrects the underlying anatomic abnormality, does not require reapproximation of the eyelid margin, and is relatively easy to perform. The lateral canthal region is injected with lidocaine 2% mixed with 1:100,000 epinephrine using a 27- or 30-gauge needle. After ensuring appropriate anesthesia, Stevens scissors are used to create a lateral canthotomy and exposure of the lateral orbital rim.
Management of Orbital Cellulitis
Authors: Johnson Thomas E. , Hui Jennifer I.
Published: November 2020

Orbital cellulitis is an acute infectious inflammation of the post-septal orbital tissues. This chapter outlines the medical and surgical management of bacterial orbital cellulitis. The paranasal sinus complex is the most common source of orbital bacterial infection. Over 50% of orbital cellulitis cases result from secondary extension from the paranasal sinuses. Other causes of orbital cellulitis include spread from ocular and periocular infections such as dacryoadenitis, dacryocystitis, and panophthalmitis; trauma, insect bites, or surgery; or endogenous sources in immunocompromised or septic patients. Orbital cellulitis resulting from sinusitis is believed to start with viral or allergic inflammation of the upper respiratory system. The inflammation decreases mucociliary clearance and causes obstruction of the sinus ostia. The sinus mucosa absorbs air, thereby creating negative pressure within the sinuses. Transudation occurs, creating a nutrient medium for bacteria. Aerobic and facultative organisms proliferate, and inflammatory products accumulate resulting in decreasing oxygen tension and pH. As inflammatory products are produced, sinus pressure increases, causing mucosal blood flow to decrease. A proliferation of obligate anaerobes occurs as aerobic bacteria consume the remaining oxygen. Young children are less likely to develop anaerobic conditions within their sinuses because their ratio of ostia size to sinus volume is much larger than that of adults. The sinus cavities enlarge markedly with age while the ostia remain approximately the same size. Thus, as children become adults, the decreased ratio of ostia size to total sinus volume increases the propensity for anaerobic sinus infections. The bony walls shared by the orbit and sinuses account for approximately half of the orbital surface area. Bacteria and inflammatory products from the sinuses may extend directly into the orbit through the neurovascular foramina, congenital bony dehiscences, anastomosing valveless venous channels, or compromised bony walls in cases of osteitis and necrosis secondary to sinusitis. An abscess may form in the subperiosteal area, a relatively avascular potential space. Subperiosteal abscesses most often involve the medial orbital wall, as it is the thinnest wall and is adjacent to the ethmoid sinuses.
Upper Eyelid Blepharoplasty
Authors: Poll Jed , Yen Michael T.
Published: November 2020

The purpose of this chapter on blepharoplasty is to familiarize the reader with relevant eyelid anatomy, appropriate preoperative evaluation, and the surgical fundamentals of upper eyelid blepharoplasty. In addition, modern modifications of blepharoplasty will be presented, with special attention to aesthetic blepharoplasty and surgical considerations in the Asian eyelid. Blepharoplasty defines a group of surgical procedures by which excess skin, orbicularis muscle, and orbital fat are removed from the upper eyelids. The ideal goal of blepharoplasty is to rejuvenate the eyelid and restore a youthful eyelid position without compromising eyelid function. A postoperative taut upper eyelid resulting in lagophthalmos and ocular surface compromise equates to an unsatisfied patient and surgeon. Likewise, excessive orbital fat excision can create a sunken superior sulcus and an eyelid contour with an undesirable cosmetic appearance. Similar to many other oculoplastic procedures, many variations in surgical technique in blepharoplasty have been employed over the years. Despite the differences, all these modifications rely upon the same underlying fundamental principles. Key steps in successful blepharoplasty surgery occur before the first skin incision is made. The eyelids are not islands unto themselves; rather, they are intimately connected to other facial structures, most notably the brow and forehead for upper lid blepharoplasty and the midface complex for lower lid blepharoplasty. Failure to preoperatively address pertinent nearby structures can yield unwanted postsurgical results. In addition to the assessment of facial structure, a preoperative blepharoplasty evaluation should include a proper medical and ocular history. Patients with a bleeding diathesis or a history of anticoagulation should be counseled and anticoagulation medications withheld if medically appropriate. A history of ocular surface issues or previous anterior segment surgery should be investigated and a slit-lamp examination performed to assess for dryness and corneal pathology. Conditions that can affect eyelid position, such as myasthenia gravis and thyroid-related orbitopathy, should be stable for a minimum of 6 months prior to blepharoplasty. Assessing brow position and function is essential when considering a patient for upper eyelid blepharoplasty. Normal brow position in males is along the superior orbital rim, and in females normal brow position is about 1 cm superior to the orbital rim.
Botulinum Toxin Injections for Facial Rhytides
Authors: Foster Jill A. , Ohr Matthew P.
Published: November 2020

Once feared for its deadly properties, Botulinum toxin is now revered for its effectiveness as a treatment in minimally invasive facial rejuvenation. The injection of Botulinum toxin is the most frequently performed nonsurgical cosmetic procedure, with at least 4.8 million procedures in 2009. First approved by the U.S. Food and Drug Administration (FDA) in 1979 for the treatment of strabismus, Botulinum toxin was shown to be both safe and effective for use to decrease muscle function. Botulinum toxin’s cosmetic applications were first recognized when it was noted that facial rhytides improved in the areas of treatment with the toxin when it was used for noncosmetic applications in the late 1980s and early 1990s. FDA approval for cosmetic treatment of the glabellar furrows was announced in 2002, and off-label aesthetic indications have continued to evolve. Botulinum toxin is produced by the gram-positive, anaerobic Clostridium botulinum. The neurotoxin acts on the peripheral nervous system, where it inhibits release of acetylcholine from the presynaptic terminal at the neuromuscular junction. There are seven distinct antigenic Botulinum toxins (BTX-A, B, C, D, E, F, and G) produced by different strains of C. botulinum. The human nervous system is susceptible to only five of these serotypes (BTX-A, B, E, F, G), and types A and B are currently available for human injection. In the United States, there are four commercially available Botulinum toxin preparations: three types of Botulinum toxin type A, OnabotulinumtoxinA or Botox Cosmetic® (Allergan, Inc., Irvine, CA), IncobotulinumtoxinA or Xeomin (Merz, Frankfort Germany), and abobotulinumtoxinA or Dysport (Medicis, Scottsdale, AZ). There is one preparation of Botulinum toxin type B, RimabotulinumtoxinB or Myobloc® (Elan Pharmaceuticals, San Diego, CA). Other Botulinum toxin type A products are anticipated to come to the U.S. market in the next decade as well. Different formulations of Botulinum toxin type A are biochemically unique and are not necessarily equivalent in dosing. The Botox unit is three times as potent as the Dysport unit, but this conversion ratio does not take into consideration safety or antigenic potential. Practically speaking, a range of 2.5 to 3 to one has been recommended to make Dysport dosing approximate the effects of Botox.
Velo-cardio-facial Syndrome
Authors: Antshel Kevin M. , Shprintzen Robert
Published: November 2020

Velo-cardio-facial syndrome (VCFS) is caused by an interstitial deletion from chromosome 22 at the 22q11 band. It is the most common microdeletion syndrome yet identified in humans, with a population prevalence of approximately 1 in 2,000 (Robin & Shprintzen, 2005). Velo-cardio-facial syndrome is known by a number of other names based on other reports in the literature that described individual components of the syndrome from a number of different perspectives. These include: DiGeorge syndrome, 22q11.2 deletion syndrome, Sedlačková syndrome, conotruncal anomalies face syndrome, and Cayler syndrome (Robin & Shprintzen, 2005). Structural anomalies affect nearly every part and system of the body and may include congenital heart disease, palatal defects, thymic hypoplasia, and endocrine disorders (Robin & Shprintzen, 2005). Velo-cardio-facial syndrome is the most common genetic cause of conotruncal heart anomalies and the most common genetic cause of cleft palate (Shprintzen et al., 2005) in addition to being the most significant genetic cause of mental illness yet identified. The earliest cases of VCFS to appear in the medical literature were probably those reported by Sedlačková in 1955 (E. Sedlačková, 1955). Sedlačková proposed a mechanism of neurologic and developmental anomalies that caused abnormalities of the palate leading to hypernasal speech and lack of facial animation caused by abnormal neurologic innervation (E. Sedlačková, 1967). The same disorder was described in 1968 by DiGeorge (DiGeorge, 1968) and by Kretschmer (Kretschmer, Say, Brown, & Rosen, 1968) who described endocrine and immunologic disorders associated with congenital heart disease. The 1st person, however, to delineate this disorder as a genetic syndrome was Strong (Strong, 1968), with his description of a single family with an affected mother and 3 affected children. Larger numbers of cases with broader phenotypic descriptions and multiple familial cases with a clear autosomal dominant pattern of inheritance followed (Shprintzen et al., 1978; Shprintzen, Goldberg, Young, & Wolford, 1981; Williams, Shprintzen, & Goldberg, 1985) thereby confirming that VCFS was a genetic syndrome. In the years that followed, the phenotypic spectrum of VCFS was expanded in a small series of papers.
Pediatric Human Immunodeficiency Virus
Authors: Willen Elizabeth J. , Cuadra Anai
Published: November 2020

Of the approximately 33.2 million people living with human immunodeficiency virus (HIV) infection or acquired immune deficiency syndrome (AIDS) globally, it is estimated that about 2.1 million are children under the age of 15 (UNAIDS Annual Report 2007), with the vast majority of cases found in the developing world and particularly Sub-Saharan Africa. Over 90% of these infections occur through vertical transmission; that is, the virus is passed from mother to infant during the preor perinatal period, or through breast-feeding (UNAIDS 2007). Although medical management of the virus continues to improve both in the United States and around the world, the negative effects of this disease continue to impact these youngest and most vulnerable members of society in significant ways. In particular, neurocognitive deficits associated with HIV and AIDS in children are common, and vertically infected children are at increased risk for a host of neurocognitive consequences due to both the direct and indirect impact of HIV on the developing central nervous system (CNS) (Armstrong, Seidel, and Swales 1993; Mintz 1996; Knight et al., 2000). Such disruptions to the normal neurodevelopmental course may yield a variety of outcomes, from relatively mild symptoms, to severe and global cognitive compromise. These disparate outcomes appear related to multiple factors including specific disease factors, such as level of immunosuppression and the nature of the insult to the brain (Mintz 1999), the occurrence of severe infection or comorbid conditions during sensitive developmental periods (Armstrong et al., 1993; Armstrong and Mulhern, 1999; Mintz, 1999; Mitchell, 2001), as well as the timing of highly active antiretroviral therapy (HAART) initiation (Hazra et al., 2007; Mintz, 1999; Mitchell, 2001). Moreover, HIV is associated with a host of other stressors that may profoundly affect developmental trajectories above and beyond the impact of the virus alone. These include extreme poverty, malnutrition, prenatal drug exposure, and loss of primary care giver through illness or death (Armstrong et al., 1993; Coscia et al., 2001).
Essential Mathematics
Authors: Oriakhi Christopher O.
Published: November 2020

Significant figures are the number of digits in a measured or calculated value that are statistically significant or offer reasonable and reliable information. Significant figures in any measurement usually contain digits that are known with certainty and one digit that is uncertain. To determine the number of significant figures, follow these rules. 1. All nonzero digits (1–9) are significant. For example, 125 has 3 significant figures and 14.44 has 4 significant figures. 2. Leading zeros to the left of the first nonzero digit in the number are not significant. They are only used to fix the position of the decimal. For example: • 0.007 has one significant figure • 0.000105 has 3 significant figures • 0.000000000015 has 2 significant figures 3. Zeros between nonzero digits are significant. For example: • 5.005 has 4 significant figures • 50.05 has 4 significant figures • 500.0000075 has 10 significant figures 4. All zeros to the right of the decimal point in a number greater than 1 are significant. For example: • 25.00 has 4 significant figures • 0.1250 has 4 significant figures • 0.2000 has 4 significant figures 5. Zeros at the end of a number may or may not be significant. They are significant only if there is a decimal point in the number. For example: • 1500 has 2 significant figures • 1500. has 4 significant figures • 602,000,000,000,000,000,000,000 has 3 significant figures • 404,570,000 has 5 significant figures • 404,590,000. has 9 significant figures Rounding off is a process of eliminating nonsignificant digits from a calculated number. The rules governing rounding off are summarized below: 1. If the nonsignificant digit is less than 5, round it and all digits to its right off. For example, 100.5129 is equal to 100.5 if rounded off to 4 significant figures. 2. If the nonsignificant digit to the right of the last digit to be retained is a 5 followed by zeros, the last digit is increased by one if it is odd, and is left unchanged if it is even. For example, 64.750 is 64.8 to 3 significant digits, but 25.850 is 25.8 to 3 significant figures.
Structure of the Atom
Authors: Oriakhi Christopher O.
Published: November 2020

The arrangement of electrons around the nucleus of an atom is known as its electronic structure. Since electrons determine all the chemical and most physical properties of an atomic system, it is important to understand the electronic structure. Much of our understanding has come from spectroscopy, the analysis of the light absorbed or emitted by a substance. Electromagnetic radiation is a form of energy; light is the most familiar type of electromagnetic radiation. But radio waves, microwaves, X-rays, and many other similar phenomena are also types of electromagnetic radiation. All these exhibit wavelike properties, and all travel through a vacuum at the speed of light. The wavelike propagation of electromagnetic radiation can be described by its frequency (ν), wavelength (λ), and speed (c). Wavelength (lambda, λ): The wavelength of a wave is the distance between two successive peaks or troughs. Frequency (nu, ν): The frequency of a wave is the number of waves (or cycles) that pass a given point in space in one second. The unit is expressed as the reciprocal of seconds (s−1) or as hertz (Hz). A hertz is one cycle per second (1 Hz = 1 s−1). Speed of light (c): The speed of light in a vacuum is one of the fundamental constants of nature, and does not vary with the wavelength. It has a numerical value of 2.9979 × 108 m/s, but for convenience we use 3.0 × 108 m/s. These measurements are related by the equation: Speed of light =Wavelength×Frequency c = λν This expression can be rearranged to give: λ = c/v, or ν = c/λ Wave number (⊽): The wave number is a characteristic of a wave that is proportional to energy. It is defined as the number of wavelengths per unit of length (usually in centimeter, cm).Wave number may be expressed as ⊽ =1/λ While electromagnetic radiation behaves like a wave, with characteristic frequency and wavelength, experiment has shown that electromagnetic radiation also behaves as a continuous stream of particles or energy packets.
The First Episode of Psychosis
Authors: Compton Michael T , Broussard Beth
Published: November 2020

The First Episode of Psychosis is the ideal book for patients experiencing the frightening and confusing initial episode of psychosis, which often occurs during late adolescence or early adulthood, and which affects nearly 3% of all people over the course of their lifetime. The book covers a range of disorders, focusing on primary psychotic disorders such as schizophrenia and schizophreniform disorder, clearly describing symptoms, early warning signs, and treatment--information that is essential for patients and families faced with the challenges posed by psychosis. The book also discusses psychiatric evaluation, healthy lifestyle choices, and the stigma often associated with mental illnesses. Worksheets allow readers to keep records of symptoms to facilitate communication with care providers, and an extensive glossary clarifies the dizzying array of terms used by medical professionals. Optimistic, practical, and recovery-oriented, The First Episode of Psychosis will help patients and their families to take an active, informed role in their care to ensure the best possible prognosis.
Widening the Circle of Influence
Authors: Newman Richard S.
Published: November 2020

Although known as “Mr. Clean” for his longtime environmental advocacy, Edmund Muskie had little knowledge of the American hazardous waste grid until 1978. A congressional sponsor of the landmark Clean Air and Clean Water Acts, the senator from Maine epitomized environmental politics. In fact, a few months before the Love Canal crisis unfolded, Muskie proposed yet another federal environmental law: a “comprehensive scheme to assure full protection of our national resources” in the wake of oil drilling disasters, tanker spills and toxic train derailments. Yet Muskie soon realized that his plan omitted something important: hazardous waste dumps. Love Canal had illuminated the toxic perils many Americans faced in their own neighborhoods. With an EPA study showing that tens of thousands of old toxic sites had yet to be contained, it was clear that the everyday landscape of homes, playgrounds, and schools needed environmental protection too. “In our society,” Muskie told an interviewer in the late 1970s, ...we are discovering almost every day, in almost every day’s newspaper, new hazards that have been released into the atmosphere over the period of our industrial revolution. [They] suddenly crop up in Love Canal, up in New York State … to create enormous hazards to public health, property values, to people. So we are constantly dealing with problems that [we] were not anticipating, which suddenly create almost insoluble problems for people and communities … [A]ll of these poisons and toxic materials were buried in landfill sites here, there, and elsewhere and sadly begin leaking in underground water, or into lakes and rivers, streams[,] only to rise up to hit people in the face with disease, with cancer, declining property values so on.... For Muskie, Love Canal was revelatory. It showed that federal law lagged behind the mounting problem of hazardous waste. After hearing Love Canal residents’ testimony, he believed that the time had come for a national statute governing toxic waste remediation—what he would refer to as a “clean land” law.
The Transparent Body
Authors: van Santen Rutger , Khoe Djan , Vermeer Bram
Published: November 2020

The “easy” diseases have pretty much been beaten in the Western world, leaving doctors to contend with the more complex illnesses that stealthily overrun the body. Two-thirds of the deaths in the United States are now attributable to cancer or coronary disease. By the time these conditions manifest themselves, it’s often too late to intervene. Treatment is only likely to succeed if early signs of cancerous growth or clogging arteries can be detected. A tumor measuring a few millimeters across is plainly less threatening than one the size of a tennis ball, not least because there is less risk of metastasis at an early stage. The focus is therefore on enhancing rapid diagnosis, which in turn means improving medical imaging. Eighty percent of all diagnoses are based on images. Yet many small but life-threatening physical processes are still missed by the scanners, echographs, and other devices that peer inside our bodies. Growths measuring less than a centimeter tend to be overlooked, so scientists are constantly working on techniques capable of offering a more detailed internal picture. Breakthroughs in imaging technology can mean the difference between life and death. They’ll enable us to intervene sooner, boosting the patient’s survival chances. Little more than a generation ago, X-rays were the only means we had of looking inside the human body. The images they produce are flat, however, and lacking in depth information, which can make them hard to interpret. An ingenious technique was therefore devised in the 1970s that allowed a single three-dimensional image to be created by combining a series of X-ray photographs. The CT (computerized tomography) scan was the first technique to produce a genuine three-dimensional image of our insides. Doctors could now tell, for instance, whether an abnormality was located on top of a bone or beneath it. Several other techniques for producing three-dimensional images of the body have since become available, some of which require patients to be injected with a contrast agent to highlight specific parts of the body.
Screening in Diabetes Care: Detecting and Managing Depression in Diabetes
Authors: Hermanns Norbert , Kulzer Bernhard
Published: November 2020

The analysis of depression screening in diabetes according to the four criteria of the United Kingdom’s National Screening Committee shows that both screening tests and treatment options are available. However, results of the Cochrane meta-analysis about depression screening in primary care settings indicate that the implementation of depression screening needs a structured approach to link these two components. A stepped-care approach comprising verification of positive screening results, treatment options, assessment of response to treatment, and adaptation may carry favorable results with regard to reduction of depression as well as cost-effectiveness. The association between diabetes and distress has long been recognized. In 1685 Thomas Willis, a British physician, suggested that diabetes might be a consequence of prolonged sorrow. In the middle of the 20th century Alexander regarded diabetes as one of the seven major psychosomatic diseases. In more recent years these historical observations have been supported by growing empirical evidence of a special relationship between emotional distress and diabetes. A meta-analysis regarding depression and diabetes onset showed that the presence of depressed symptoms increased the risk of developing diabetes by 37%. However, the effect is bidirectional. Meta-analytic findings suggest that the comorbidity of depression and diabetes is frequent: approximately one third of diabetic patients report symptoms of depression, and a smaller group of10%of diabetic patients meet the criteria of a clinical depression. In diabetes care settings the recognition rate of depression in diabetic patients is disappointingly low, ranging between20%and50%. Even in more specialized diabetes care settings approximately 50% of depressed diabetic patients remain undetected. Thus, there are strong and compelling arguments in favor of depression screening in diabetes, and this is also recommended by several guidelines for diabetes care (Fig. 16.1). However, there are also arguments against depression screening. Studies analyzing the effectiveness of depression screening in primary care settings do not all support large-scale implementation of depression screening. Increasingly, there is a need to justify depression screening in different medical conditions with regard to its effectiveness and ethical and clinical implications and to specify whether screening as a routine or more selective case-finding is warranted.12 Screening for depression potentially exposes both false positives and true positives (but otherwise unrecognized cases) to stigmatization and potential discrimination by health insurance companies or employers.
Wound Healing In Glaucoma
Authors: Mankiewicz Kimberly A. , Seibold Leonard K.
Published: November 2020

The goal of wound healing in most surgeries is to bring the injured tissue back to its original state to prevent the wound from reopening. However, in glaucoma surgery, the goal is to have incomplete wound healing. Scar formation prevents the filtering mechanism and bleb from functioning properly, leading to poor pressure control and failure of the surgery. However, if there is too little wound healing, surgical failure may be marked by overfiltration and hypotony. Several modulators are currently used in conjunction with glaucoma surgery, and new targets are under investigation to improve our ability to control the healing process. Normal wound healing occurs in 3 phases: the inflammatory phase, the proliferative/repair phase, and the remodeling phase. In the inflammatory phase, blood cells and plasma proteins are released around the wound site. These proteins attract other wound healing factors, such as cytokines and growth factors. White blood cells are also recruited to the site, clearing out undesired cellular debris through phagocytosis. Additionally, platelet aggregation and fibrin clot formation occur. In the proliferative/repair phase, fibroblasts, crucial cells for tissue repair and scarring, begin reforming the extracellular matrix (ECM) and other components of connective tissue. Angiogenesis also occurs, and the wound begins to close. In the final phase, blood vessels are resorbed and fibroblasts disperse. Fibroblasts produce matrix metalloproteinases that, along with collagen and elastin, allowing for wound remodeling and scar formation. The modulators used in glaucoma surgery, as well as new agents in development, disrupt various aspects of this cycle. Use of topical corticosteroids in conjunction with filtering surgery is a routine part of postoperative management and has been for many decades. Corticosteroids blunt the wound healing response by altering the inflammatory phase through reducing the amount of inflammatory cells and cytokines that migrate to the wound site. Corticosteroids also prevent the complexing and conversion of inflammatory mediators, as well as reduce vascular permeability to limit mobility of wound healing factors to the wound site.
Cataracts and Visual Axis Opacities
Authors: Berdahl John P. , Samuelson Thomas W.
Published: November 2020

Glaucoma surgery can result in worsened visual acuity. This worsening may result from alterations to the ocular structures in the visual axis during or following surgery. This outcome is often troublesome for advanced glaucoma patients with severely restricted visual fields as they are very dependent on the remaining central island of vision. In patients with less severe glaucoma, postsurgical loss of acuity may be their first symptom of glaucoma. Many conditions result in decreased visual acuity following glaucoma surgery, and appropriate management of these complications is important for maintaining visual acuity. Cataract is the most common cause of decreased visual acuity after filtering surgery. Filtering surgery increases the 5-year risk of developing a visually significant cataract by 78%. The reason for cataract formation following trabeculectomy is unclear. The most accepted hypothesis is that aqueous dynamics are altered by trabeculectomy surgery. A surgical peripheral iridectomy is typically performed as part of a trabeculectomy, which permits aqueous to pass directly from the posterior chamber to the anterior chamber without first supplying nutrition to the anterior lens. This theory is consistent with the observation that cataracts are more common after laser peripheral iridotomy. Inadvertent puncture of the lens capsule during trabeculectomy surgery is also a potential cause (see Chapter 7). Another proposed cause of cataract formation is postoperative inflammation, although plausible, convincing evidence is lacking. Increased cataract formation has been observed with the use of mitomycin-C (MMC) and may be due either to increased aqueous outflow bypassing the lens or direct toxicity to the lens. Surgical complications such as intraoperative or postoperative flat anterior chamber with lens-cornea touch increase the risk of cataract formation. Additionally, postoperative medications, especially corticosteroids, are also known to be associated with cataract formation. The risk of cataract formation from topical ocular steroids is difficult to determine because of the many confounding variables.. However, the odds ratio of cataract formation from systemic and inhaled chronic corticosteroid use is approximately 1.5–2.0. The surgeon should bear potential steroid effects in mind during the postoperative period in phakic patients.
Diplopia and Ocular Motility Disturbances
Authors: Pirouzian Amir A.
Published: November 2020

Strabismus and diplopia have been reported with tube shunt implants in glaucoma surgery in several case series. Overall, the reports of strabismus (vertical and horizontal) as a potentially disabling surgical complication widely range from 5% to 100% depending on the type of tube shunt used. The challenge in determining the exact incidence of strabismus after tube shunt implantation arises from a lack of accurate preoperative strabismus evaluation and documentation in the published studies, as well as a higher incidence of reduced peripheral fusion and visual acuity in these selected groups of patients. The mechanism of postoperative strabismus is likely due to one of the following: 1) the size and the height of the device inserted and the resulting mass effect (bleb size); 2) the technique of surgical placement; 3) postoperative surgical adhesion, scar formation, and restriction; 4) probable muscle ischemia in conjunction with antifibrotic agents; 5) fat adherence syndrome; and 6) muscle-tendon stretching. Understanding the mechanism of strabismus is important for prevention and treatment of this condition. The mass effect following tube shunt implantation has been noted in multiple studies however, the true pathophysiology remains unclear. A proposed mechanism of postoperative ocular dysmotility suggests a direct mass effect on the extraocular muscles (EOM) from the implant or the encapsulated cystic bleb surrounding the device. Use of a large device or creation of a highly elevated bleb may shift an EOM pulley from its original anatomical pathway, thus creating a heterotopic pulley phenomenon. Therefore extreme caution and thorough preoperative counseling should be exercised in those patients with an already restricted peripheral sensory fusion because even a minor shift in extraocular muscle alignment may compromise the patient’s ability to maintain fusion and trigger the development of a secondary strabismus. Selection of the smallest device for an appropriate reduction of intraocular pressure (IOP) is also strongly advised in such patients. The newer generation of Baerveldt® implants with fenestrated plates (Abbot Medical Optics, Inc., Santa Ana, California) and flexible plate Ahmed™ valves (New World Medical, Inc., Rancho Cucamonga, California) may result in a lower bleb height, which will decrease the compressive effect on an individual EOM and its pulley system.
Tube Shunt Related Complications of the Anterior Chamber
Authors: Gokhale Parag A.
Published: November 2020

Postoperative complications in the anterior chamber can affect both glaucoma progression and vision. Preoperative considerations and surgical technique are important to reduce and prevent these complications. A flat anterior chamber is one of the most common complications following tube shunt surgery, occurring at a rate of 3.5%– 27%. Although often associated with hypotony and choroidal effusions and usually due to increased outflow after surgery, it may also be related to decreased aqueous production, especially in eyes with previous ciliary body ablation. Increased outflow could result from leakage around the tube or overfiltration either before fibrous capsule formation over the plate or through tube fenestrations. Diagnosis of the cause of hypotony can be made with a careful slit-lamp examination. Leakage around the tube can be viewed internally by gonioscopy, though a flat or shallow anterior chamber can make seeing potential leakage difficult. The location of overfiltration can be determined by looking at areas of conjunctival elevation. Conjunctival bleb formation at the limbus could help identify leakage around the tube at its scleral tunnel insertion. Early elevation of a bleb over the reservoir of a tube shunt is also seen with incomplete occlusion in the nonvalved (or sometimes valved) tube. Elevation near the tube-plate junction could also indicate overflow at a fenestration but is unusual. Intracameral irrigation of fluorescein can help identify the source of leakage. A flat anterior chamber associated with hypotony can have serious sequelae, including corneal edema, cataract, and failure of the procedure. Medical treatment to deepen the anterior chamber with cycloplegics and reduction of wound healing inhibitors should be tried first but is often insufficient, as this treatment will not quickly eliminate the source of leakage. More aggressive intervention will be needed if there is central flattening (Grade 2 or 3 flat chamber). Identifying the source of leakage is important in determining management. If there is leakage at the site of the tube’s entry into the sclera, viscoelastic may be needed to fill the anterior chamber. Air injection is an alternative that allows for continued visualization of the leak if desired.