Modeling ion implantation of HgCdTe

Ion implantation of boron is used to create n on p photodiodes in vacancy-doped mercury cadmium telluride (MC.T). The junction is formed by Hg interstitials from the implant damage region diffusing into the MC.T and annihilating Hg vacancies. The resultant doping profile is n⁺/n^-/p, where the n⁺ region is near the surface and roughly coincides with the implant damage, the n^- region is where Hg vacancies have been annihilated revealing a residual grown-in donor, and the p region remains doped by Hg vacancy double acceptors. We have recently developed a new process modeling tool for simulating junction formation in MC.T by ion implantation. The interstitial source in the damage region is represented by stored interstitials whose distribution depends on the implant dose. These interstitials are released into the bulk at a constant, user defined rate. Once released, they diffuse away from the damage region and annihilate any Hg vacancies they encounter. In this paper, we present results of simulations using this tool and show how it can be used to quantitatively analyze the effects of variations in processing conditions, including implant dose, annealing temperature, and doping background.     

Alteration of Sertoli cell differentiation in the presence of carcinoma in situ in human testes

PURPOSE: We investigated Sertoli cells in testicular biopsies with carcinoma in situ (CIS) in respect to cytokeratin expression to elucidate the status of Sertoli cell differentiation adjacent to CIS in human testes. Cytokeratin 18 intermediate filaments indicate a state of undifferentiation usually observed in Sertoli cells of prepubertal testes. MATERIALS AND METHODS: 29 testicular biopsies presenting CIS were investigated by means of immunohistochemistry, using a polyclonal antibody against placental-alkaline phosphatase to detect CIS cells and a monoclonal antibody against human cytokeratin 18 to show expression of cytokeratin 18 intermediate filaments in Sertoli cells. RESULTS: All tubules bearing CIS showed positive cytokeratin expression of Sertoli cells if tubules were devoid of normal germ cells. However, a total of 13 specimen revealed CIS cells together with normal germ cells. In the presence of CIS cells together with round or elongated spermatids, adjacent Sertoli cells did not express cytokeratin immunoreactivity. In the case of combined presence of CIS and spermatogonia and primary spermatocytes, Sertoli cells could be found either immunopositive or immunonegative, and were positive in tubules with CIS and spermatogonia only. CONCLUSIONS: Sertoli cells associated with CIS cells undergo a process of dedifferentiation, seen by the re-expression of cytokeratin intermediate filaments. We suggest that this dedifferentiation results in a loss of Sertoli cell function and leads to a cessation of spermatogenic activity.     

Intralesional radiolabeled human monoclonal IgM in human tumor xenografts

Sensory-perceptual abnormalities in people with autism are discussed from two perspectives: published firsthand accounts and existing psychological research evidence. A range of abnormalities, including hyper- and hyposensitivity, sensory distortion and overload, and multichannel receptivity and processing difficulties, are described in firsthand accounts and frequently portrayed as central to the autistic experience. A number of dangers are inherent in uncritically accepting these accounts at face value and in any wider generalization to the autistic population as a whole. Evidence from clinical studies suggests that unusual sensory responses are present in a majority of autistic children, that they are manifested very early in development, and that they may be linked with other aspects of autistic behavior. In addition, experimental studies using a range of indices have found evidence of unusual responses to sensory stimuli in autistic subjects. However the clinical and experimental research to date suffers from serious methodological limitations and more systematic investigation is warranted. Key issues for future psychological research in the area are identified.     

Object-oriented DBMS requirements

The requirements on an object-oriented DBMS for management of information in a large, complex enterprise are presented. These requirements aid in the achievement of an environment characterized by data sharing, open architectures, application and data portability, and assurance of data integrity. They were defined from the point of view of a user of the DBMS; therefore they describe the expected functionality of the DBMS and do not specify the method of implementation to achieve this functionality. They encompass requirements on the data model, query and data manipulation languages, the system architecure, interfaces to the system, change management, and transaction management.     

Central sleep apnea

A central sleep apnea is the absence of respiratory effect, and, thus, the absence of airflow during sleep. Central hypopnea, a related disorder, is also discussed. The sensory component of central sleep apnea; defects involving the integrative and executive neurons; non-neurologic causes of central sleep apneas, including chronic obstructive pulmonary disease and congestive heart failure; diagnosis; treatment; and other topics are reviewed in detail.     

Arterial reactivity is enhanced in genetic males taking high dose estrogens

OBJECTIVES: We sought to assess whether high dose estrogen treatment is associated with enhanced arterial reactivity in genetic males. BACKGROUND: Although estrogens have been shown to enhance arterial reactivity in women, and are thereby thought to confer cardiovascular benefit, the vascular effects of long-term estrogen therapy in genetic males is unknown. METHODS: We studied the arterial physiology of 30 genetic males--15 male to female transsexuals receiving long-term high dose estrogen therapy and 15 healthy male control subjects matched for age, smoking history and vessel size. Using external vascular ultrasound, brachial artery diameter was measured at rest, after flow increase (causing endothelium-dependent dilation [EDD]) and after nitroglycerin (GTN), an endothelium-independent dilator. Blood pressure, cholesterol and testosterone levels were also measured in each subject. RESULTS: Total testosterone and free testosterone index levels were lower in the transsexuals compared with the control subjects (p < 0.001). In contrast, EDD was significantly higher in the transsexuals than in the control males (mean [+/-SD] 7.1 +/- 3.1% vs. 3.2 +/- 2.8%, p = 0.001), as was the GTN response (21.2 +/- 6.7% vs. 14.6 +/- 3.3%, p = 0.002). Total and high density lipoprotein cholesterol, blood pressure levels and baseline vessel size were similar in the two groups. On multivariate analysis, enhanced EDD was associated independently with estrogen therapy (p = 0.02) and with low total cholesterol (p = 0.04). An enhanced GTN response was also significantly associated with estrogen therapy (p = 0.03). CONCLUSIONS: Long-term treatment with high dose estrogens is associated with enhanced arterial reactivity in genetic males, which may be due to the effects of estrogen excess or androgen deprivation, or both.