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.     

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.     

Hyperhomocysteinemia: detection, risk assessment, and treatment

OBJECTIVE: The aim of this study was to evaluate both the importance of the screening strategy and the familial aggregation characteristics of families with hypercholesterolemic children. PATIENTS AND METHODS: Ninety-one families (369 subjects) with one hypercholesterolemic child were studied. In addition to clinical and general biochemical evaluation, lipids including apo A-I and B-100 were examined. LDL was quantified under ultracentrifugation. RESULTS: Among the 91 children studied, 10 (10.99%) suffered heterozygous hypercholesterolemia, while 81 (89.01%) suffered polygenic hypercholesterolemia. Following a diet, polygenic children exhibited normal lipid parameters. In heterozygous children a decrease of 19% for total cholesterol, 19.9% for LDL-cholesterol and 16.3% for apo B were observed. When starting the study, 77.5% of the family members thought that they had normal serum lipid values. At the end of the study it was confirmed that only 28% were really normolipemic, indicating that 49.4% of the individual did not know that they were suffering dyslipemia. The study also showed that fathers exhibited the highest incidence of hypercholesterolemia (80.2%) followed by brothers (65.6%) and mothers (61.5%). Therefore, 69.4% of the individuals studied exhibited dyslipemia. CONCLUSIONS: The screening strategy allows one to diagnose a high percentage (almost 50%) of individuals suffering hypercholesterolemia in families with a child previously diagnosed of this pathology. Moreover, in these families there is a high degree of familiar aggregation of dyslipemia.     

The lack of long-term detrimental effects on liver allografts caused by donor-specific anti-HLA antibodies

Recent reports indicate a higher incidence of both acute and chronic liver allograft rejection when, at the time of transplantation, the recipients serum contains donor-specific anti-HLA antibodies. From 9/89 to 5/91, 133 liver allografts were performed at our institution. Thirteen liver recipients had donor-specific IgG anti-HLA antibodies (complement-fixing) at the time of transplantation. In eleven patients, antibodies reacted to donor class I antigens while in 1 patient the donor-specific antibody had class II reactivity. Twelve patients have been followed for a minimum of 12 months (median 18 months, range 28-12 months). No hyperacute rejection was seen in any of the cases and four patients had acute rejections. Thus far only one of the twelve patients has biopsy evidence suggestive of chronic liver injury. The remaining have normal liver enzymes and bilirubin. Three of these twelve patients died (one from a myocardial infarction and the others from sepsis) accounting for a one-year graft survival of 75%. There was no significant statistical difference in the one-year graft survival in those recipients without donor-specific antibodies (i.e., 80.5%). In eight of the twelve patients, pretransplant preformed antibody level (PRA) was > 50%. In six of the thirteen patients donor-specific antibody was present at dilutions greater than 1:64. As previously reported, the donor-specific antibody disappeared from the serum posttransplant within hours and did not reappear. In vitro studies demonstrated no factor in portal or hepatic artery blood that could inhibit rabbit complement mediated lysis of anti-HLA antibodies. We conclude that it is not a contraindication to do liver transplants in the presence of donor-specific anti-HLA antibodies.     

The miswak chewing stick: a traditional oral hygiene aid

The miswak chewing stick is an oral hygiene device used by the majority of people in Arab Gulf countries. Despite its widespread use, few studies demonstrated its benefits or applications as an alternative and convenient means for cleansing the teeth. This paper will examine the unique properties of the miswak chewing stick and its proper use.     

Genetic control of immunity to Heligmosomoides polygyrus: presentation of promiscuous antigens to parasite-specific T cell hybridomas

The role of MHC class II in the presentation of Heligmosomoides polygyrus antigens has been investigated, using a number of T cell hybridomas produced in A and E positive and negative mice. By using fixed and irradiated antigen presenting cells (APC), further evidence has emerged, to support earlier data, that there can be differential processing requirements during the presentation of H. polygyrus antigens by A and E molecules. In concordance with these earlier observations, this work provides further evidence than individual T cells can respond to antigen when presented by more than one MHC molecule. Previously, this evidence has been restricted to individual MHC molecules of the same haplotype, but these data show that H. polygyrus produces antigens which can be presented by both syngeneic and allogeneic MHC molecules. These antigens do not appear to be synonymous with the previously described H. polygyrus superantigen, as presentation is restricted to specific MHC haplotypes. It is proposed that H. polygyrus may produce these antigenic molecules as part of its strategy to manipulate the host immune system.     

What's the use of being happy? Mood states, useful objects, and repetition priming effects.

Two experiments involving 99 undergraduate participants sought to examine the influence of mood states on encoding speed within lexical decision and pronunciation tasks. Mood states were measured naturalistically in Experiment 1 and manipulated in Experiment 2. Stimuli consisted of nouns representing useful (e.g., food) and nonuseful (e.g., lint) objects. Mood states had no implications for initial encoding speed. However, when the same words were presented a 2nd time (i.e., repeated), happy individuals displayed a tendency to encode useful words faster than nonuseful ones. Thus, mood states influenced repetition priming on the basis of stimulus valence. The authors propose that happiness sensitizes individuals to useful or rewarding objects, which in turn creates a stronger memory trace for such stimuli in the future. (PsycINFO Database Record (c) 2010 APA, all rights reserved)