2,552 research outputs found

    Correlation between hot-carrier-induced interface states and GIDL current increase in N-MOSFET's

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    Correlation between created interface states and GIDL current increase in n-MOSFET's during hot-carrier stress is quantitatively discussed. A trap-assisted two-step tunneling model is used to relate the increased interface-state density (ADH) with the shift in GIDL current (ΔI d). Results show that under appropriate drain-gate biases, the two-step tunneling is so dominant that A/d is insensitive to temperatures up to about 50 °C. With the help of 2-D device simulation, the locations of the drain region with significant two-step tunneling and the energy levels of the traps involved can be found, with both depending on the drain voltage. From these insights on ADit,A/d and their relation, A Du near the midgap can be estimated, with an error less than 10% as compared to the results of chargepumping measurement on the same transistors. Devices with nitrided gate oxide, different gate-oxide thicknesses and different channel dimensions are also tested to verify the above correlation. © 1998 IEEE.published_or_final_versio

    Solubility of strontium-substituted apatite by solid titration

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    Solid titration was used to explore the solubility isotherms of partially (Srx-HAp, x = 1, 5, 10, 40, 60 mol.%) and fully substituted strontium hydroxyapatite (Sr-HAp). Solubility increased with increasing strontium content. No phase other than strontium-substituted HAp, corresponding to the original titrant, was detected in the solid present at equilibrium; in particular, dicalcium hydrogen phosphate was not detected at low pH. The increase in solubility with strontium content is interpreted as a destabilization of the crystal structure by the larger strontium ion. Carbonated HAp was formed in simulated body fluid containing carbonate on seeding with Sr10-HAp, but the precipitate was strontium-substituted on seeding with Sr-HAp. Strontium-substituted HAp might be usable as a template for the growth of new bone, since nucleation appears to be facilitated. © 2008 Acta Materialia Inc.postprin

    Solubility of strontium-substituted apatite by solid titration

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    Solid titration was used to explore the solubility isotherms of partially (Srx-HAp, x = 1, 5, 10, 40, 60 mol.%) and fully substituted strontium hydroxyapatite (Sr-HAp). Solubility increased with increasing strontium content. No phase other than strontium-substituted HAp, corresponding to the original titrant, was detected in the solid present at equilibrium; in particular, dicalcium hydrogen phosphate was not detected at low pH. The increase in solubility with strontium content is interpreted as a destabilization of the crystal structure by the larger strontium ion. Carbonated HAp was formed in simulated body fluid containing carbonate on seeding with Sr10-HAp, but the precipitate was strontium-substituted on seeding with Sr-HAp. Strontium-substituted HAp might be usable as a template for the growth of new bone, since nucleation appears to be facilitated. © 2008 Acta Materialia Inc.postprin

    A pilot controlled trial of a combination of dense cranial electroacupuncture stimulation and body acupuncture for post-stroke depression

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    Our previous studies have demonstrated the treatment benefits of dense cranial electroacupuncture stimulation (DCEAS), a novel brain stimulation therapy in patients with major depression, postpartum depression and obsessive-compulsive disorder. The purpose of the present study was to further evaluate the effectiveness of DCEAS combined with body acupuncture and selective serotonin reuptake inhibitors (SSRIs) in patients with post-stroke depression (PSD).published_or_final_versio

    Search for electromagnetic properties of the neutrinos at the LHC

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    Exclusive production of neutrinos via photon-photon fusion provides an excellent opportunity to probe electromagnetic properties of the neutrinos at the LHC. We explore the potential of processes pp-> p gamma gamma p -> p nu anti-nu p and pp -> p gamma gamma p -> p nu anti-nu Z p to probe neutrino-photon and neutrino-two photon couplings. We show that these reactions provide more than seven orders of magnitude improvement in neutrino-two photon couplings compared to LEP limits.Comment: 11 pages, 4 tables, New backgrounds have been adde

    Genome-wide signatures of convergent evolution in echolocating mammals

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    Evolution is typically thought to proceed through divergence of genes, proteins, and ultimately phenotypes(1-3). However, similar traits might also evolve convergently in unrelated taxa due to similar selection pressures(4,5). Adaptive phenotypic convergence is widespread in nature, and recent results from a handful of genes have suggested that this phenomenon is powerful enough to also drive recurrent evolution at the sequence level(6-9). Where homoplasious substitutions do occur these have long been considered the result of neutral processes. However, recent studies have demonstrated that adaptive convergent sequence evolution can be detected in vertebrates using statistical methods that model parallel evolution(9,10) although the extent to which sequence convergence between genera occurs across genomes is unknown. Here we analyse genomic sequence data in mammals that have independently evolved echolocation and show for the first time that convergence is not a rare process restricted to a handful of loci but is instead widespread, continuously distributed and commonly driven by natural selection acting on a small number of sites per locus. Systematic analyses of convergent sequence evolution in 805,053 amino acids within 2,326 orthologous coding gene sequences compared across 22 mammals (including four new bat genomes) revealed signatures consistent with convergence in nearly 200 loci. Strong and significant support for convergence among bats and the dolphin was seen in numerous genes linked to hearing or deafness, consistent with an involvement in echolocation. Surprisingly we also found convergence in many genes linked to vision: the convergent signal of many sensory genes was robustly correlated with the strength of natural selection. This first attempt to detect genome-wide convergent sequence evolution across divergent taxa reveals the phenomenon to be much more pervasive than previously recognised

    The influence of multi-morbidity and self-reported socio-economic standing on the prevalence of depression in an elderly Hong Kong population

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    <b>Background</b> There has been an increasing prevalence of both depression and chronic medical conditions globally but the relationship between depression and multi-morbidity is not well understood. The aim of the present study was to investigate the relationship between depression, multi-morbidity (number of chronic medical conditions, and measures of socioeconomic standing (SES) in an elderly Hong Kong population.<p></p> <b>Methods</b> Cross sectional study. Information on clinically relevant depressive symptoms, measured by the Geriatric Depression Scale (GDS), and demographic and chronic medical conditions were collected using standardized questionnaires. Information collected on SES included educational status (ES), maximum ever income (MEI), and self-perceived social standing in local community (SES-COM) and in Hong Kong generally (SES-HK). Analysis was conducted using multiple logistic regression.<p></p> <b>Results</b> Depression rates were similar in men and women (GDS caseness 8.1% vs 8.4%). Multi-morbidity of chronic medical conditions was common (40% of men and 46% of women had three or more). In the overall sample, the prevalence of depression was associated with the number of chronic medical conditions (OR 1.27; CI: 1.16–1.39). In addition, SES-HK and SES-COM were significant independent variables.<p></p> <b>Conclusion</b> In this elderly Hong Kong population, depression prevalence rose markedly with number of chronic medical conditions and SES-HK and SES-COM

    Survival Differences by Race/Ethnicity and Treatment for Localized Hepatocellular Carcinoma Within the United States

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    Racial differences among hepatocellular carcinoma survival have been reported, but the etiology behind these disparities remains unclear. Using multi-variable logistic regression analysis, our restrospective cohort study investigated the demographic disparities in survival among localized hepatocellular carcinoma in the United States. From 1998 to 2001, 2,776 cases of localized hepatocellular carcinoma were identified. Significant racial/ethnic disparities in overall survival and utilization of therapies were identified. Compared with non-Hispanic white males, black females were 56% less likely to survive 3 years (OR 0.44; 95% CI 0.21–0.93). Treatment-specific models also demonstrated disparities, e.g., compared with non-Hispanic whites, Asians receiving transplantation were 77% more likely to survive 3 years (OR, 1.77; 95% CI 1.28–2.44). There are significant racial/ethnic disparities in 3-year survival among patients with localized hepatocellular carcinoma. These differences are partially explained by demographic differences in utilization of therapy and in stage-specific survival for each therapy

    Survival and hepatitis status among Asian Americans with hepatocellular carcinoma treated without liver transplantation

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    <p>Abstract</p> <p>Background</p> <p>Chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) are established causes of HCC. HCC patients are often diagnosed late and receive palliative therapies, however, the survival of Asian American patients with HCC treated without transplantation has not been well studied. We reviewed our institution's experience to determine predictors and rates of survival in Asian American HCC patients treated without transplantation.</p> <p>Methods</p> <p>We identified Asian American patients with HCC referred to M. D. Anderson Cancer Center. Patients were tested for HBV and HCV. Survival curves were generated by Kaplan-Meier method. Multivariate Cox proportional hazards regression was used to test the relationship between prognostic factors and survival.</p> <p>Results</p> <p>Of 82 Asian American HCC patients, most had advanced disease (65%) and received treatment (68%); however, only 11% had surgical resection. 94% had positive anti-HBc and 61% had positive HBsAg. 20% had positive anti-HCV. There were no significant changes in the rates of HBV and HCV over time. Male gender, high alpha-fetoprotein levels, and stage IV disease were associated with shorter survival Overall median survival was 9.2 months (95% CI 6.5–11.9), and the survival of HCV and HBV patients was not statistically different.</p> <p>Conclusion</p> <p>The survival rate of Asian American patients with advanced HCC, for whom transplantation was not available, was low. Timely hepatitis screening and interventions by primary care physicians may be the most logical solution to reduce the burden of hepatitis-associated HCC among Asian Americans.</p

    Clinical Presentation of Hepatocellular Carcinoma (HCC) in Asian-Americans Versus Non-Asian-Americans

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    The incidence of HCC is rising worldwide. Studies on ethnicity-based clinical presentation of HCC remain limited. The aim is to compare the clinical presentation and stage of HCC between Asian-Americans and non-Asian-Americans. This retrospective study assessed ethnicity-based differences in HCC presentation, including demographics, laboratory results, diagnosis of underlying liver disease, and stage of HCC. Of 276 patients, 162 were Asian-Americans and 114 were non-Asian-Americans. Compared to non-Asian-Americans, Asian-Americans had a significantly higher incidence of history of hepatitis B virus (HBV) infection (55.0% vs. 4.9%, P < 0.001), family history of HBV infection (12.5% vs. 0.0%, P < 0.001) and HCC (15.2% vs. 2.9%, P = 0.002), but lower incidence of history of hepatitis C virus (HCV) infection (37.5% vs. 61.6%, P < 0.001). At diagnosis of HCC, Asian-American patients had a significantly lower frequency of hepatic encephalopathy (8.9% vs. 29.3%, P = 0.001), and ascites (26.7% vs. 57.3%, P < 0.001). Asian-Americans had lower Child-Pugh scores (class A: 62.0% vs. 31.4%, P < 0.001), and MELD scores (9.2 ± 4.4 vs. 12.0 ± 6.4, P = 0.02), and presented with a lower stage of HCC by Okuda staging (I: 43.8% vs. 22.8%, P = 0.001). Asian-American patients with HCC presented with a higher incidence of history and family history of HBV infection, lower incidence of hepatic decompensation, lower Child and MELD scores, and an early stage HCC disease
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