Determination of energy barrier profiles for high-k dielectric materials utilizing bias-dependent internal photoemission

We utilize bias-dependent internal photoemission spectroscopy to determine the metal/dielectric/silicon energy barrier profiles for Au/HfO2/Si and Au/Al2O3/Si structures. The results indicate that the applied voltage plays a large role in determining the effective barrier height and we attribute much of the variation in this case to image potential barrier lowering in measurements of single layers. By measuring current at both positive and negative voltages, we are able to measure the band offsets from Si and also to determine the flatband voltage and the barrier asymmetry at 0 V. Our SiO2 calibration sample yielded a conduction band offset value of 3.03+/-0.1 eV. Measurements on HfO2 give a conduction band offset value of 2.7+/-0.2 eV (at 1.0 V) and Al2O3 gives an offset of 3.3+/-0.1 (at 1.0 V). We believe that interfacial SiO2 layers may dominate the electron transport from silicon for these films. The Au/HfO2 barrier height was found to be 3.6+/-0.1 eV while the Au/Al2O3 barrier is 3.5+/-0.1 eV

Mutant Neurogenin-3 in congenital malabsorptive diarrhea

Background: Neurogenin-3 (NEUROG3) is expressed in endocrine progenitor cells and is required for endocrine-cell development in the pancreas and intestine. The NEUROG3 gene (NEUROG3) is therefore a candidate for the cause of a newly discovered autosomal recessive disorder characterized by generalized malabsorption and a paucity of enteroendocrine cells. Methods: We screened genomic DNA from three unrelated patients with sparse enteroendocrine cells for mutations of NEUROG3. We then tested the ability of the observed mutations to alter NEUROG3 function, using in vitro and in vivo assays. Results: The patients had few intestinal enteroendocrine cells positive for chromogranin A, but they had normal numbers of Paneth\u27s, goblet, and absorptive cells. We identified two homozygous mutations in NEUROG3, both of which rendered the NEUROG3 protein unable to activate NEUROD1, a downstream target of NEUROG3, and compromised the ability of NEUROG3 to bind to an E-box element in the NEUROD1 promoter. The injection of wild-type but not mutant NEUROG3 messenger RNA into xenopus embryos induced NEUROD1 expression. Conclusions: A newly discovered disorder characterized by malabsorptive diarrhea and a lack of intestinal enteroendocrine cells is caused by loss-of-function mutations in NEUROG3. Copyright © 2006 Massachusetts Medical Society

Social Work with Children Affected by Domestic Violence: An Analysis of Policy and Practice Implications

The past decade has seen an increasing awareness of the emotional harm to children that can ensue from exposure to domestic violence. This article develops a framework for understanding social work responses, using an analysis of recent developments in British policy as an example. It is argued that to understand what these developments mean in practice we need to develop our analysis of the value perspectives underpinning them. Issues facing those charged with implementing these sometimes ambiguous policy and practice changes are discussed in three levels of intervention: the macro, the intermediate, and the 'street-level.' The article concludes by calling for closer collaboration between policy makers, practitioners and service users in the co-production of policy

Silicic volcanism on Mars evidenced by tridymite in high-SiO2 sedimentary rock at Gale crater

Tridymite, a SiO2 mineral that crystallizes at low pressures and high temperatures (>870 °C) from high-SiO2 materials, was detected at high concentrations in a sedimentary mudstone in Gale crater, Mars. Mineralogy and abundance were determined by X-ray diffraction using the Chemistry and Mineralogy instrument on the Mars Science Laboratory rover Curiosity. Terrestrial tridymite is commonly associated with silicic volcanism where high temperatures and high-silica magmas prevail, so this occurrence is the first in situ mineralogical evidence for martian silicic volcanism. Multistep processes, including high-temperature alteration of silica-rich residues of acid sulfate leaching, are alternate formation pathways for martian tridymite but are less likely. The unexpected discovery of tridymite is further evidence of the complexity of igneous petrogenesis on Mars, with igneous evolution to high-SiO2 compositions

A rapid, reproducible, noninvasive predictor of liver graft survival

BACKGROUND: Clinical and laboratory criteria are not reliable predictors of deceased donor liver graft quality. Intraoperative assessment of experienced surgeons is the gold standard. Standardizing and quantifying this assessment is especially needed now that regional sharing is the rule. We prospectively evaluated a novel, simple, rapid, noninvasive, quantitative measure of liver function performed before graft procurement. MATERIALS AND METHODS: Using a portable, finger-probe–based device, indocyanine green plasma disappearance rates (ICG-PDR) were measured in adult brain-dead donors in the local donor service area before organ procurement. Results were compared with graft function and outcomes. Both donor and recipient teams were blinded to ICG-PDR measurements. RESULTS: Measurements were performed on 53 consecutive donors. Eleven liver grafts were declined by all centers because of quality; the other 42 grafts were transplanted. Logistic regression analysis showed ICG-PDR to be the only donor variable to be significantly associated with 7-d graft survival. Donor risk index, donor age, and transaminase levels at peak or procurement were not significantly associated with 7-d graft survival. CONCLUSIONS: We report the successful use of a portable quantitative means of measuring liver function and its association with graft survival. These data warrant further exploration in a variety of settings to evaluate acceptable values for donated liver grafts

Reoperative Complications after Primary Orthotopic Liver Transplantation: A Contemporary Single-Center Experience in the Post–Model for End-Stage Liver Disease Era

BackgroundData on complications requiring reoperation after orthotopic liver transplantation (OLT) are limited. We sought to describe the spectrum of reoperative complications after OLT, evaluate the associations with graft and patient survival, and identify predictors of need for reoperation.Study designWe retrospectively studied adult patients who underwent primary OLT at our institution from February 2002 to July 2012. The primary outcomes included occurrence of a reoperative complication. Secondary outcomes were graft and patient survival. Multivariable logistic regression analysis was used to model the associations of recipient, donor, and operative variables with reoperation.ResultsOf 1,620 patients, 470 (29%) had complications requiring reoperation. The most common reoperative complication was bleeding (17.3%). Compared with patients not requiring reoperation, patients with reoperative complications had greater Model for End-Stage Liver Disease scores and need for pretransplantation hospitalization, mechanical ventilation, vasopressors, and renal replacement therapy; considerably longer cold and warm ischemia times and greater intraoperative blood transfusion requirements; and substantially worse 1-, 3-, and 5-year graft and patient survival rates. In multivariable analysis, predictors of reoperative complications included intraoperative transfusion of packed RBCs (odds ratio [OR] = 2.21; 95% CI, 1.91-2.56), donor length of hospitalization >8 days (OR = 1.87; 95% CI, 1.28-2.73), recipient pretransplantation mechanical ventilation (OR = 1.65; 95% CI, 1.21-2.24), cold ischemia time >9 hours (OR = 1.63; 95% CI, 1.23-2.17), warm ischemia time >55 minutes (OR = 1.58; 95% CI, 1.02-2.44), earlier major abdominal surgery (OR = 1.41; 95% CI, 1.03-1.92), and elevated donor serum sodium (OR = 1.17; 95% CI, 1.03-1.31).ConclusionsPatients who require reoperation for complications after OLT have high pretransplantation acuity and inferior post-transplantation survival. We identified factors associated with reoperative complications to guide perioperative donor-recipient matching and improve outcomes

Evaluation of the XRCC1 gene as a phenotypic modifier in BRCA1/2 mutation carriers. Results from the consortium of investigators of modifiers of BRCA1/BRCA2

Item does not contain fulltextBACKGROUND: Single-nucleotide polymorphisms (SNPs) in genes involved in DNA repair are good candidates to be tested as phenotypic modifiers for carriers of mutations in the high-risk susceptibility genes BRCA1 and BRCA2. The base excision repair (BER) pathway could be particularly interesting given the relation of synthetic lethality that exists between one of the components of the pathway, PARP1, and both BRCA1 and BRCA2. In this study, we have evaluated the XRCC1 gene that participates in the BER pathway, as phenotypic modifier of BRCA1 and BRCA2. METHODS: Three common SNPs in the gene, c.-77C>T (rs3213245) p.Arg280His (rs25489) and p.Gln399Arg (rs25487) were analysed in a series of 701 BRCA1 and 576 BRCA2 mutation carriers. RESULTS: An association was observed between p.Arg280His-rs25489 and breast cancer risk for BRCA2 mutation carriers, with rare homozygotes at increased risk relative to common homozygotes (hazard ratio: 22.3, 95% confidence interval: 14.3-34, P<0.001). This association was further tested in a second series of 4480 BRCA1 and 3016 BRCA2 mutation carriers from the Consortium of Investigators of Modifiers of BRCA1 and BRCA2. CONCLUSIONS AND INTERPRETATION: No evidence of association was found when the larger series was analysed which lead us to conclude that none of the three SNPs are significant modifiers of breast cancer risk for mutation carriers