Co-Director, Donald and Barbara School of Medicine at Hofstra/Northwell
U U Pu Th U Cf Table Important nuclides for photoneutron production Nuclide Threshold Et (MeV) (-Q value) impotence in young men buy 75 mg viagra otc. Reaction H Li Li Li H( impotence with blood pressure medication buy cheap viagra on line, n) H Li( erectile dysfunction surgical treatment options generic 25 mg viagra visa, n + p) He Li( erectile dysfunction performance anxiety buy generic viagra 75 mg online, n) Li Li(, n) Li Be(, n) Be C(, n) C Be C In reactor shielding analyses, the gamma photons encountered have energies too low, and most materials have a photoneutron threshold too high for photoneutrons to be of concern. Only for a few light elements, listed in > Table, are the thresholds for photoneutron production sufficiently low that these secondary neutrons may have to be considered. In heavy water- or beryllium-moderated reactors, the photoneutron source may be very appreciable, and the neutron-field deep within a hydrogenous shield is often determined by photoneutron production in deuterium, which constitutes about. Capture gamma photons arising from neutron absorption have particularly high energies and, thus, may cause a significant production of energetic photoneutrons. The photoneutron mechanism can be used to create laboratory neutron sources by mixing intimately a beryllium or deuterium compound with a radioisotope that decays with the emission of high-energy photons. Alternatively, the encapsulated radioisotope may be surrounded Radiation Shielding and Radiological Protection by a beryllium- or deuterium-bearing shell. One very attractive feature of such (, n) sources is the nearly monoenergetic nature of the neutrons if the photons are monoenergetic. However, in large sources, the neutrons may undergo significant scattering in the source material, and thereby degrade the nearly monoenergetic nature of their spectrum. These photoneutron sources generally require careful usage because of their inherently large, photon emission rates. Because only a small fraction of the high-energy photons (typically, -) actually interact with the source material to produce a neutron, these sources generate gamma rays that are of far greater biological concern than the neutrons. Neutrons from (, n) Reactions Many compact neutron sources use energetic alpha particles from various radioisotopes (emitters) to induce (, n) reactions in appropriate materials (converters). Although a large number of nuclides emit neutrons if bombarded with alpha particles of sufficient energy, the energies of the alpha particles from radioisotopes are capable of penetrating the Coulombic potential barriers of only the lighter nuclei. Of particular interest are those light isotopes for which the (, n) reaction is exothermic (Q >) or, at least, has a low threshold energy (see > Table). Thus, for an (, n) reaction to occur, the alpha particle must have enough energy to penetrate the Coulomb barrier, and exceed the threshold energy. Alpha particles emitted by uranium and plutonium range between and MeV and can cause (, n) neutron production when in the presence of oxygen or fluorine. A neutron source can be fabricated by mixing intimately one of the converter isotopes listed in > Table with an alpha-particle emitter. Most of the practical alpha emitters are actinide elements, which form intermetallic compounds with beryllium. Target Reaction Be Be B Be(, n) C Be(, n) B(, n) N B O F B(, n) N O(, n) Ne F(, n) Na Radiation Shielding and Radiological Protection ensures both that the emitted alpha particles immediately encounter converter nuclei, thereby producing a maximum neutron yield, and that the radioactive actinides are bound into the source material, thereby reducing the risk of leakage of the alpha-emitting component. The neutron yield from an (, n) source varies strongly with the converter material, the energy of the alpha particle, and the relative concentrations of the emitter and converter elements. The degree of mixing between the converter and emitter, and the size, geometry, and source encapsulation may also affect the neutron yield. The energy distributions of neutrons emitted from all such sources are continuous below some maximum neutron energy with definite structure at well-defined energies determined by the energy levels of the converter and the excited product nuclei. The use of the same converter material with different alpha emitters produces similar neutron spectra with different portions of the same basic spectrum accentuated or reduced as a result of the different alpha-particle energies. Generally, neutrons emitted from the Be(, n) reaction have higher energies than those produced by other (, n) sources because Be has a larger Q value than that of other converters. The structure in the Be-produced neutron spectrum above MeV can be interpreted in terms of structure in the Be(, n) C cross section, which in turn depends on the excitation state in which the C nucleus is left. A large peak below MeV in the Be neutron spectrum arises not from the direct (, n) reaction, but from the "breakup" reaction Be(,) Be B + n. As the alpha-particle energy increases, both the fraction of neutrons emitted from the breakup reaction (E n < MeV) and the probability that the product nucleus is left in an excited state (E n < MeV) increase, thereby decreasing slightly the average neutron energy (see > Table). In all (, n) sources, there is a maximum neutron energy corresponding to the reaction in which the product nucleus is left in the ground state and the neutron appears in the same direction as that of the incident alpha particle (=).
Rarely impotence yahoo purchase viagra 25 mg fast delivery, a patient comes to the hospital for some other medical reason and it is found that he or she has been living quietly in the community impotence for males buy viagra 75mg with amex, preoccupied with a bizarre delusional system yet appearing neither depressed nor schizophrenic erectile dysfunction protocol pdf free order viagra 100mg. Certainly one often sees delusions in depressed patients who decompensate as their depression deepens erectile dysfunction needle injection video purchase genuine viagra on line. Sharply separated from the more or less pure delusional disorders are the ones that occur as part of a confusional state or delirium. Delusions occurring in the latter setting are characteristically bizarre, changeable, poorly systematized, and, with rare exceptions, transitory; they are associated with many other aberrations of mental function. The same can be said for delusions that occur in the early stages of a dementing disease. Such events are common, of course, in elderly persons with an incipient or wellcompensated dementia ("beclouded dementia," page 363). Rarely, one of the degenerative dementing diseases of middle and late life (Alzheimer, Huntington, and especially Lewy body) presents with a delusional disorder. Otherwise healthy persons without known mental illness may experience a brief delusional episode, notably after surgical procedure or the administration of sedative drugs. In most, there are no subsequent mental problems but a proportion of these older patients will be found to later develop dementia. Certain drugs have a tendency to produce paranoia in otherwise nonpsychotic individuals; phencyclidine, amphetamine, and cocaine are the main offenders seen in patients arriving in emergency departments, and anticholinergic drugs are often responsible in hospitalized patients. In a general hospital, where most of our paranoid patients have been depressed or manic, we have several times been gratified by the effects of antidepressant or antipsychotic medication. In the treatment of patients with pathologic jealousy, Mooney has found phenothiazine drugs to be useful. From what has been said, the clinical analysis of patients with delusions requires a careful study of mood and intelligence to rule out manic-depressive psychosis and dementia. If either of these two states exists, the treatment proceeds along the lines discussed in Chaps. A matter of practical importance is for the physician to evaluate carefully the nature of the delusional ideas and try to judge whether the patient is homicidal or suicidal. Occasionally, physicians and others have been killed or maimed by patients with paranoia who thought they were being mistreated. These patients were without family history or prepsychotic schizoid personality and seemed to have a better prognosis than one usually expects in schizophrenia. In the diagnosis of postpartum psychosis, one must also keep in mind the possibility of eclampsia, the consequences of pituitary infarction, cerebral vein thrombosis or transitory stroke of arterial type, ergot-induced psychosis, and hypotensive-hypoxic cerebral injury. If these conditions were no more than examples of drug-induced psychosis, they would be interesting enough. The fact is, however, that they differ considerably from the usual toxic deliria or confusional states. The syndrome, somewhat reminiscent of puerperal psychosis and some cases of "combat fatigue" seen in wartime, comprises features that are suggestive of manic-depressive psychosis or schizophrenia on the one hand and of confusional psychosis on the other. These endocrine psychoses have far-reaching medical significance, for they provide artificial models of psychoses created by the manipulation of metabolic and by exogenous factors. It is appropriate that they are in the last chapter in a book about neurology, for they provide a remarkable neurologic perspective on mental disorders. Corticosteroid and Adrenocorticotropic Hormone Psychosis First described in arthritic patients being treated with cortisone, these syndromes are now occurring far less frequently than when corticosteroids were introduced into medical practice. The psychosis usually develops over a period of a few days after the patient has received the hormone for a week or more. Depression and insomnia are the most frequent early symptoms, but some patients become elated, agitated, excited, and talkative, as though under pressure to speak, while others are mute; or the prevailing emotional response may be one of anxiety and panic. However, clouding of the sensorium and disorientation, the hallmarks of deliria and the confusional psychoses, have not been prominent. Nevertheless, the state of awareness is not altogether normal, and at times the patient is frankly bewildered. In the motor sphere there may be incessant activity or immobility, resistiveness, and even negativism verging on catatonia.
The linguistic and cognitive approaches to alexia required the development of models for normal reading erectile dysfunction treatment hypnosis discount 50mg viagra free shipping. Several partially coincidental cognitive models of normal reading have been proposed (Coltheart erectile dysfunction from nerve damage order discount viagra line, 1978; Caramazza et al impotence only with wife order viagra 100 mg online. In general erectile dysfunction age viagra 100 mg mastercard, most of these models propose that after initial letter identification, reading proceeds along two linguistically different routes: (1) the direct route, wherein the written word is associated with a visual word in lexical memory; and (2) the indirect route, wherein the written word is Aphasia Handbook 104 transformed into a spoken word following a graphophonemic set of rules, and the meaning of the word is attained through its phonological mediation. If one or the other of these reading systems is altered, different error patterns can be observed. Classical alexia subtypes the classic alexic syndromes include alexia without agraphia, alexia with agraphia, frontal alexia and spatial (or visuospatial) alexia. Alexia without agraphia the syndrome has been given many different names including alexia without agraphia, pure alexia, pure word blindness, agnosic alexia, occipital alexia, posterior alexia, verbal alexia, and more recently, letter-by-letter reading. The core clinical features include a serious disturbance in reading contrasted with a preservation of writing competency. Patients with occipital alexia find themselves unable to read what they have just written. Reading letters (literal reading) is relatively preserved, and reading words (verbal reading) is seriously impaired. Sometimes, the patient fragments the letter when reading and reads only the initial letter segment (eg, "K" is read as "l"). Letter-by-letter reading aloud eventually can result in word Aphasia Handbook 105 recognition. Patients with this type of reading disorder appear to use an inefficient eye movement strategy in reading, fixating to the left of the usual normal viewing location of words; consequently, less of the word is processed, with the refixation rate increasing and reading becomes slower (McDonald et al. It is notable that not only is the recognition of letters and words clearly impaired but also the recognition of fragmented pictures, suggesting an inefficient build-up of sensory representations (Starrfelt et al. The process of reading individual letters aloud to recognize the word is slow and open to error, particularly on long words; reading time is proportional to the number of letters in a word, but this effect differs according to the degree of associated hemianopia (Sheldon et al 2012). Morphological paralexias (the misreading of the final morphemes) is a common characteristic of occipital alexia (eg, "closing" is read as "closed"). Patients with occipital alexia can recognize words spelled out loud to them, and they can recognize letters outlined on the palm of the hand. Damage usually includes the left medial and inferior occipital region, particularly the fusiform and lingual gyri and the posterior segment of the geniculocalcarine pathway (Figure 6. Left occipital damage may result in alexia for two reasons, which may coexist depending on the distribution of the lesion. A lesion of the left lateroventral prestriate cortex or its afferents impairs word recognition ("pure" alexia). If the left primary visual cortex or its afferents are destroyed, resulting in a complete right homonymous hemianopia, rightward saccades during text reading are disrupted ("hemianoptic" alexia) (Leff et al. Impairments in oculomotor behavior during reading have been documented in this group of patients; they present a disproportionate increase in the number and duration of fixations per word and in the regressive saccades per word, suggesting that pure alexia could be the result of a general reduction of visual speed and span (Starrfelt et al 2009). It has been suggested that brain lesions in patients with pure alexia and functional imaging data support that the abstract letter identities (visual word form) are subtended by a restricted patch of lefthemispheric fusiform cortex, which is activated during reading (Kleinschmidt & Cohen 2006). Cortical stimulation of the left posterior fusiform and inferior temporal gyri results in pure alexia (Mani et al 2008). Noteworthy, associative visual agnosia is frequently observed in pure alexia, but prosopagnosia is rarely found. Alexia with agraphia Other names used to refer to this reading disorder are central alexia, parietal-temporal alexia, literal alexia, and letter-blindness. The characterizing features of this alexia are the impairments of reading and writing: alexia and agraphia. The alexia is a literal alexia (inability to read letters) resulting in a total alexia. Their ability to copy written and printed words is far superior to their ability to write them spontaneously or from dictation. They also have difficulty in transposing cursive to printed forms and vice versa (Benson 1985). Some residual reading abilities (such as some preserved ability to recognize shape and canonical orientation of letters) have been reported, but these residual abilities probably are supported by the right hemisphere (Volpato et al 2012).
The mood change should be accompanied by increased energy and several of the symptoms referred to above (particularly pressure of speech how does an erectile dysfunction pump work purchase 50mg viagra with amex, decreased need for sleep impotence gels buy viagra 50 mg low price, grandiosity erectile dysfunction treatments that work order viagra, and excessive optimism) erectile dysfunction doctors in charleston sc 100 mg viagra with mastercard. Inflated self-esteem and grandiose ideas may develop into delusions, and irritability and suspiciousness into delusions of persecution. In severe cases, grandiose or religious delusions of identity or role may be prominent, and flight of ideas and pressure of speech may result in the individual becoming incomprehensible. Severe and sustained physical activity and excitement may result in aggression or violence, and neglect of eating, drinking, and personal hygiene may result in dangerous states of dehydration and self-neglect. If required, delusions or hallucinations can be specified as congruent or incongruent with the mood. Patients with mania that is responding to neuroleptic medication may present a similar diagnostic problem at the stage when they have returned to normal levels of physical and mental activity but still have delusions or hallucinations. Characteristically, recovery is usually complete between episodes, and the incidence in the two sexes is more nearly equal than in other mood disorders. As patients who suffer only from repeated episodes of mania are comparatively rare, and resemble (in their family history, premorbid personality, age of onset, and long-term prognosis) those who also have at least occasional episodes of depression, such patients are classified as bipolar (F31. Manic episodes usually begin abruptly and last for between 2 weeks and 4-5 months (median duration about 4 months). Depressions tend to last longer (median length about 6 months), though rarely for more than a year, except in the elderly. Episodes of both kinds often follow stressful life events or other mental trauma, but the presence of such stress is not essential for the diagnosis. The frequency of episodes and the pattern of remissions and relapses are both very variable, though remissions tend to get shorter as time goes on and depressions to become commoner and longer lasting after middle age. Although the original concept of "manic-depressive psychosis" also included patients who suffered only from depression, the term "manic-depressive disorder or psychosis" is now used mainly as a synonym for bipolar disorder. If required, delusions or hallucinations may be specified as congruent or incongruent with mood (see F30. A fifth character may be used to specify the presence or absence of the somatic syndrome in the current episode of depression: F31. Diagnostic guidelines Although the most typical form of bipolar disorder consists of alternating manic and depressive episodes separated by periods of normal mood, it is not uncommon for depressive mood to be accompanied for days or weeks on end by overactivity and pressure of speech, or for a manic mood and grandiosity to be accompanied by agitation and loss of energy and libido. Depressive symptoms and symptoms of hypomania or mania may also alternate rapidly, from day to day or even from hour to hour. A diagnosis of mixed bipolar affective disorder should be made only if the two sets of symptoms are both prominent for the greater part of the current episode of illness, and if that episode has lasted for at least 2 weeks. The patient may, however, be receiving treatment to reduce the risk of future episodes. Other common symptoms are: (a)reduced concentration and attention; (b)reduced self-esteem and self-confidence; (c)ideas of guilt and unworthiness (even in a mild type of episode); (d)bleak and pessimistic views of the future; (e)ideas or acts of self-harm or suicide; (f)disturbed sleep (g)diminished appetite. The lowered mood varies little from day to day, and is often unresponsive to circumstances, yet may show a characteristic diurnal variation as the day goes on. As with manic episodes, the clinical presentation shows marked individual variations, and atypical presentations are particularly common in adolescence. In some cases, anxiety, distress, and motor agitation may be more prominent at times than the depression, and the mood change may also be masked by added features such as irritability, excessive consumption of alcohol, histrionic behaviour, and exacerbation of pre-existing phobic or obsessional symptoms, or by hypochondriacal preoccupations. For depressive episodes of all three grades of severity, a duration of at least 2 weeks is usually required for diagnosis, but shorter periods may be reasonable if symptoms are unusually severe and of rapid onset. Some of the above symptoms may be marked and develop characteristic features that are widely regarded as having special clinical significance. The most typical examples of these "somatic" symptoms (see introduction to this block, page 112 [of Blue Book]) are: loss of interest or pleasure in activities that are normally enjoyable; lack of emotional reactivity to normally pleasurable surroundings and events; waking in the morning 2 hours or more before the usual time; depression worse in the morning; objective evidence of definite psychomotor retardation or agitation (remarked on or reported by other people); marked loss of appetite; weight loss (often defined as 5% or more of body weight in the past month); marked loss of libido. Usually, this somatic syndrome is not regarded as present unless about four of these symptoms are definitely present. Further depressive episodes should be classified under one of the subdivisions of recurrent depressive disorder (F33.
The age of admission to the hospital is between 20 and 40 erectile dysfunction psychological causes cheap viagra 25 mg without a prescription, with a peak between 28 to 34 years impotence reasons and treatment buy viagra on line. The economic burden created by this disease is enormous- in 1990 erectile dysfunction treatment for heart patients purchase line viagra, the direct and indirect costs in the United States were estimated to be $33 billion (Rupp and Keith) erectile dysfunction quality of life buy viagra toronto. It is unlike the condition that prevails in delirium and other confusional states, dementia, and depression. Some patients with chronic schizophrenia, before the onset of a flagrant psychosis or when in remission, show none of the schneiderian first-rank symptoms and- during brief testing of mental status- might even pass for normal. But on long-term observation they are vague and preoccupied with their own thoughts. They seem unable to think in the abstract, to understand fully figurative statements such as proverbs, or to separate relevant from irrelevant data. There is what has been called a circumstantiality and tangentiality about their remarks. Parts are confused with the whole or are clustered together or condensed in an illogical way. Opposites may be considered as identical, and conceptual relationships are distorted. In an analysis of a problem or a situation, there is a tendency to be overinclusive rather than underinclusive (as happens in dementia). In conversation and in writing, the trend of an argument or thought sequence is often interrupted abruptly, with a resulting disorder of verbal communication. There is over time a general deterioration in functioning, social withdrawal and at times bizarre actions, idleness, self-absorption, and aimlessness. In more severely affected schizophrenic patients, thinking is even more disintegrated. They appear to be totally preoccupied with their inner psychic life (thus the early use of the term autism) and may do no more than utter a series of meaningless phrases or neologisms, or their speech may be reduced to a nonsensical "word salad. At times these patients are talkative and exhibit odd behavior; at other times they are quiet and idle; in the extreme, the patients are mute or assume and maintain imposed postures or remain immobile (catalepsy). With remission, they may remember much of what has happened or they may have only fragmentary memories of events that occurred. The patient may express the thought that his body is somehow separated from his mind, that he does feel like himself, that his body belongs to someone else, or that he is unsure of his own identity or even sex. Thought insertion, wherein it seems to the patient that an idea has been implanted into his mind, or thought withdrawal, wherein an idea has been extracted from his mind by an outside agency, are other parts of this problem. Closely related, and characteristic of schizophrenia, are ideas of being under the control of some external agency or being made to speak or act in ways that are dictated by others, often through the medium of radar, telepathy, or the internet (passivity feelings). Frequently, there are ideas of reference- that the remarks or actions of others are subtly or overtly directed to the patient. Finally, the patient may feel that the world about him is changed or unnatural, or his perception of time may be altered, not in a brief episode like the jamais vu of a temporal lobe seizure, but continuously; this is the phenomenon of derealization. The voices may or may not be recognized; they may belong to one person or two or more persons who converse with the patient or with one another. Instead, they seem to come from within the patient, so that at times they cannot be distinguished from his own feelings and thoughts. Certain somatic hallucinations and delusions may predominate in any one individual. Visual, olfactory, and other types of hallucinations also occur but are much less frequent. The patient believes in the reality of these hallucinations and often weaves them into a delusional system. It should be reiterated here that hallucinations are a feature of a number of neurologic processes but in most, visual hallucinations predominate whereas auditory hallucinations are the hallmark of schizophrenia. Of interest in this regard is "The Report on the Census of Hallucinations" by Sidgwick in 1894 that suggested (as cited by Frith) that almost one in ten ostensibly normal respondents had experienced hallucinations, mostly visual. The illnesses in which hallucinations and delusions are prominent, for example hallucinogenic drug ingestion and the Charles Bonnet syndrome (see pages 220 and 405), have been reviewed by Frith. Of interest has been the belated affirmation of the importance of negative symptoms in schizophrenia. Liddle and Barnes, looking objectively at all aspects of schizophrenic thought and behavior, divided them into four groups: (1) flat affect, diminution in expressive gestures, latency of response, reduced spontaneous movements, apathy, restricted recreational activities, inability to feel intimate or close, and motor retardation.
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