An EM approach to mineral analysis using natural gamma rays

We describe here a method for the analysis of materials on a conveyor belt using the natural gamma spectra collected with a BGO (Bismuth Germanate) gamma ray detector. This detector collects gamma ray emissions from the Potassium (K), Uranium (U), and Thorium (Th) atoms in the materials. Based on these data, and using a Poisson model for the data generation, a statistical model is proposed and an approximate maximum likelihood (ML) technique based on the expectation-maximization (EM) algorithm is then used to estimate the amount of each of the three elements in the material. The statistical model is further refined to incorporate parameters of drift in the detector and an estimation technique for this is developed and tested against real data. The Cramér–Rao lower bounds for the estimators are calculated.     

A Managed IPv6 Transitioning Architecture for Large Network Deployments

With IPv6 transitioning still in a relative state of flux, the need has emerged for methods to control this crucial aspect of IPv6 deployments. This article makes the case for transitioning architectures as a realistic solution to this issue, specifically within large-scale networks. The Site Transitioning Architecture (STA) supports the deployment, operation, and management of IPv6 transitioning mechanisms. The authors provide an overview of the STA's design and operation, noting that its flexible, simple, and secure architecture is suitable for the duration of the IPv6 deployment process, regardless of the underlying network environment.     

Molecular structures and conformational studies of triarylcyclopropyl and related nonsteroidal antiestrogens

Molecular structures and conformational characteristics of a series of 1,1-dichloro-2,2,3-triarylcyclopropanes (DTACs), which were reported previously to be distinctly antiestrogenic and inhibitors of the estrogen-receptor-positive MCF-7 human breast cancer cells in culture, are reported. In addition, structural and conformational features of the DTACs were compared to the first-known nonsteroidal antiestrogen, MER25, and the clinically useful antiestrogen Tamoxifen. The molecular structures of four DTAC compounds were determined by X-ray diffraction. Crystallographic structures show that the DTAC molecules have nearly the same relative conformation for the three aryl rings which is designated as a "nonpropeller" conformation in contrast to the observed "propeller" conformation for the three rings in all known triarylethylenes. Systematic conformational searches were performed to find the conformational preferences of DTACs, MER25, and Tamoxifen using idealized model compounds built from their respective crystal structure. Energy-minimization and conformational-search studies demonstrated that all DTAC molecules have a common, single global minimum energy conformer for their central core containing the dichlorotriarylcyclopropyl system, which is similar to that found in their crystal structures. Conformational search of MER25 showed that the molecule can assume a number of low-energy conformers of which two, one anti (A1) and one gauche (G1A), have about the same energy. The anti conformation is similar to the one observed in its crystal structure and resembles the estrogenic E-isomer of Tamoxifen, while the lowest energy gauche conformer of MER25 resembles more closely the antiestrogenic Z-isomer of Tamoxifen. NMR spectroscopic analysis of MER25 showed that the molecule exists predominantly in the anti conformation in solution. A comparative review of the structural features and bioactivities of Tamoxifen, DTACs, and MER25 provides a possible explanation for their low estrogen receptor binding affinity which is common to these compounds together with their antiestrogenic activity.     

Research on encoding and decoding of non-binary polar codes over GF(2m)

Binary Polar Codes (BPCs) have advantages of high-efficiency and capacity-achieving but suffer from large latency due to the Successive-Cancellation List (SCL) decoding. Non-Binary Polar Codes (NBPCs) have been investigated to obtain the performance gains and reduce latency under the implementation of parallel architectures for multi-bit decoding. However, most of the existing works only focus on the Reed-Solomon matrix-based NBPCs and the probability domain-based non-binary polar decoding, which lack flexible structure and have a large computation amount in the decoding process, while little attention has been paid to general non-binary kernel-based NBPCs and Log-Likelihood Ratio (LLR) based decoding methods. In this paper, we consider a scheme of NBPCs with a general structure over GF(2^m). Specifically, we pursue a detailed Monte-Carlo simulation implementation to determine the construction for proposed NBPCs. For non-binary polar decoding, an SCL decoding based on LLRs is proposed for NBPCs, which can be implemented with non-binary kernels of arbitrary size. Moreover, we propose a Perfect Polarization-Based SCL (PPB-SCL) algorithm based on LLRs to reduce decoding complexity by deriving a new update function of path metric for NBPCs and eliminating the path splitting process at perfect polarized (i.e., highly reliable) positions. Simulation results show that the bit error rate of the proposed NBPCs significantly outperforms that of BPCs. In addition, the proposed PPB-SCL decoding obtains about a 40% complexity reduction of SCL decoding for NBPCs.     

Platelet-derived growth factor-specific regulation of the JE promoter in rat aortic smooth muscle cells

JE is a member of the family of "immediate early" genes induced by growth factors and cytokines. JE encodes a low molecular weight secretory glycoprotein analogous to the human monocyte chemoattractant protein, MCP-1. JE and MCP-1 proteins are thought to play an important role in inflammation and in the recruitment of monocyte/macrophages to the vessel wall during the development of atherosclerosis. We have previously reported that the induction of JE in rat aortic smooth muscle cells (SMC) was specific to platelet-derived growth factor (PDGF) and was not seen with other growth agonists. Using a luciferase reporter system and transient transfection assays of rat aortic SMC, we now report the identification of a region in the proximal rat JE promoter that is responsive to PDGF but not to other growth factors (angiotensin II and alpha-thrombin) or cytokines (interleukin 1-beta and tumor necrosis factor-alpha). The full response to PDGF (approximately 6-fold) requires the cooperative activity of two potentially novel cis-acting elements, at positions -146 to -128 and -84 to -59. While each element produces a different pattern in electrophoretic mobility shift assays, they appear to bind the same PDGF-responsive species. Further analysis of these regions should provide important insights into PDGF-specific responses in vascular SMC.     

Evaluating medication response in ADHD: cognitive, behavioral, and single-subject methodology

We introduce a novel application for linkage analysis: using bone marrow donor-recipient sib pairs to search for genes influential in graft-versus-host disease (GVHD), a major cause of morbidity and mortality following allogeneic bone marrow transplantation. In particular, we show that transplant sib pairs in which the recipient developed severe GVHD can be used to map genes in the same way as traditional discordant (affected/unaffected) sib pairs (DSPs). For a plausible GVHD model, we demonstrate that the transplant/discordant sib pair analog of the "possible triangle test" [Holmans (1993) Am J Hum Genet 52:362-374] has similar power to that of the simpler "restricted test" proposed by Risch [(1990b) Am J Hum Genet 46:229-241; (1992) Am J Hum Genet 51:673-675]. Moreover, we show that the restricted test has superior power in much of the DSP possible triangle and significantly inferior power in only a small region. Thus, we conclude that the restricted test is preferable for localizing genes with transplant/discordant sib pairs. Finally, we examine the effects of heterogeneity on the power to detect GVHD loci and demonstrate the gain in efficiency by dividing the sample into genetically more homogeneous subgroups.     

Extension of a typology of alcohol dependence based on relative genetic and environmental loading

Mild, severe, and dyssocial subtypes of alcohol dependence, previously identified among Caucasian men from the Epidemiologic Catchment Area study, were also identified among Caucasian men and women with DSM-IV alcohol dependence from the National Longitudinal Alcohol Epidemiologic Survey (n = 2,703; 1,746 respectively). These subtypes were not identified among African American and Hispanic American men or women with DSM-IV alcohol dependence. Among Caucasians with alcohol dependence, the subtypes were characterized by differential loading on three dimensions: genetic, general environmental, and dyssocial environmental symptom scales developed in a prior twin study. The mild subtype (60% of men and 66% of women) was distinguished by low mean scores on all three scales; the dyssocial subtype (24% of men and 20% of women) by low mean genetic and general environmental scores but high mean dyssocial environmental scores; and the severe subtype (16% of men and 14% of women) by high scores on the genetic and general environmental scales. These subtypes also showed the expected distinctions in clinical characteristics. The severe subtype showed greater comorbid drug dependence and major depression, more treatment seeking, and a higher prevalence of parental alcoholism. The severe subtype also showed significantly greater genetic influence adjusted for overall severity of alcohol dependence (genetic ratio). Only the severe subtype showed a pattern of scale scores and clinical characteristics suggestive of substantial genetic influence. The present study indicates a robustness of the typology originally developed among DSM-III alcohol-dependent Caucasian men by empirical extension of the subtypes to a different sample of Caucasian men and, separately, Caucasian women. The use of this typology may aid in distinguishing between Caucasian alcohol-dependent individuals on the basis of relative genetic influence, enabling genetic, behavioral, and epidemiological investigations to reduce genetic or environmental "noise" and better focus on specific aspects of alcohol dependence.     

Cigarette smoking and the colorectal adenoma-carcinoma sequence: a hypothesis to explain the paradox

As recognized precursor lesions to colorectal cancer, colorectal adenomatous polyps have been studied to enhance knowledge of colorectal cancer etiology. Although most of the known risk factors for colorectal cancer are also associated with the occurrence of colorectal adenomas, cigarette smoking has had a strong, consistent relationship with colorectal adenomas but is generally not associated with colorectal cancer. The explanation for this paradox is unknown. With data collected in 1986-1988 during a large case-control study based on colonoscopy results in New York City, New York, the authors investigated the possibility that the paradox may arise because subjects with colorectal adenomas were included in the control group of cancer case-control studies. The authors found a statistically significant increased risk between heavy cigarette smoking (smokers with > or = 40 pack-years of smoking) and risk of adenoma (odds ratio (OR) = 1.61, 95% confidence interval (CI) 1.06-2.44). They saw no increased colorectal cancer risk from heavy cigarette smoking (OR = 1.02, 95% CI 0.52-1.99) using a "manufactured" control group to simulate a typical unscreened, population-based control group. When the authors compared these colorectal cancer cases with an adenoma-free control group examined by colonoscopy in a polytomous model with several case groups (newly diagnosed adenomas, carcinoma in situ, intramucosal carcinoma, and colorectal cancer), they found that the risk for 20-39 pack-years of smoking was elevated, although not statistically significant, and was similar for all four case groups. The risk for the highest smoking category (> or = 40 pack-years) was more strongly elevated in all four case groups, although it was statistically significant for only the newly diagnosed adenoma and the carcinoma in situ cases (adenomas, OR = 1.59, 95% CI 1.05-2.42; carcinoma in situ, OR = 2.05, 95% CI 1.01-4.15; intramucosal carcinoma, OR = 1.30, 95% CI 0.61-2.77; and colorectal cancer, OR = 1.30, 95% CI 0.64-2.65). While the authors' study is weakened by the lack of statistical significance concerning risk for colorectal cancer, these data offer some support for the hypothesis that the association between cigarette smoking and risk of colorectal cancer may have been masked by inclusion in the control group of subjects with adenomas. They also suggest that the major effect of smoking on the colorectal adenoma-carcinoma sequence occurs in the earlier stages of the formation of adenoma and the development of carcinoma in situ.     

Influence of hypertonic saline solution infusion on defibrillation efficacy

BACKGROUND: Transplantation of lung allografts from the same donor into 2 recipients ("twinning") provides an opportunity to study recipient and donor factors that influence early allograft function. METHODS: Twenty-seven pairs of recipients were identified and evaluated using multivariate logistic regression analysis (p < 0.05). Four measures of early graft function were analyzed: alveolar-arterial gradient in the operating room, first alveolar-arterial gradient in the intensive care unit, alveolar-arterial gradient at 24 hours, and days of mechanical ventilation. RESULTS: Analysis of the pooled data without regard to pairing showed that alveolar-arterial gradient in the operating room was influenced by donor age, length of donor hospitalization, recipient mean pulmonary artery (PA) pressure at unclamping, and transplantation of a left lung. The alveolar-arterial gradient in the intensive care unit was correlated with donor age, donor cause of death, and mean PA pressure on arrival in that unit. Only mean PA pressure remained significant at 24 hours. Days of mechanical ventilation was determined by mean PA pressure on arrival in the intensive care unit, drop in mean PA pressure during operation, and diagnosis of the recipient. In the paired analysis, receiving a left lung, recipient diagnosis (pulmonary hypertension worse than others), and need of cardiopulmonary bypass were significantly associated with immediate graft dysfunction, although these influences did not persist beyond the immediate postoperative period. Donor arterial oxygen tension and time of ischemia were not significant predictors in any analysis. CONCLUSIONS: Immediate allograft function was associated with donor-related characteristics initially, but these lost importance over the ensuing 24 hours. Recipient PA pressure was an immediate and persisting influence. In the analysis of differences in function between the members of each pair, transplantation of the left lung, recipient diagnosis, and cardiopulmonary bypass were identified, but their influence did not persist beyond the first 6 hours.     

The effect of urinary tract reconstruction on neurologically impaired women previously treated with an indwelling urethral catheter

PURPOSE: We investigated the changes in sexuality and quality of life that evolve after lower urinary tract reconstruction in neurologically impaired women previously treated with an indwelling urethral catheter. MATERIALS AND METHODS: A total of 18 neurologically impaired women treated with an indwelling urethral catheter underwent bladder reconstruction. Pubovaginal sling urethral compression was required to restore perineal dryness in 13 patients and was the only operation required in conjunction with intermittent catheterization in 3. Eight patients underwent ileocystostomy, that is creation of a "bladder chimney," and 4 underwent augmentation cystoplasty with creation of a continent catheterizable stoma. In 3 patients ileocystoplasty alone with intermittent urethral catheterization was performed. All patients were followed 6 to 40 months (mean 18) after reconstructive surgery using a 9-part questionnaire to score numerically the effect of surgical reconstruction on sexuality and quality of life issues. RESULTS: On a scale of 0 (worst) to 5 (best) mean score for self-esteem improved from 1 preoperatively to 4 postoperatively, self-image from 1 to 4, sexual desire from 2 to 4 and ability to cope with disability from 1 to 4, respectively. In 4 of the 15 women who were sexually active preoperatively the frequency of sexual intercourse doubled from a mean of 3 to 6 times per month, respectively, and all 4 women reported improved sexual satisfaction. All 13 patients with pelvic pain and 5 with symptoms of autonomic dysreflexia noticed significant improvement if not complete resolution of the symptoms. CONCLUSIONS: Neurogenic lower urinary tract dysfunction treated with an indwelling urethral catheter is detrimental to sexuality and quality of life in neurologically impaired women. Urinary tract reconstruction restores not only quality of life but also sexuality by improving self-image, self-esteem and the ability to cope. Indwelling catheterization as a method of long-term urinary treatment should be avoided in women.