Suppression of random dopant-induced threshold voltage fluctuations in sub-0.1-μm MOSFET's with epitaxial and delta-doped channels

A detailed three-dimensional (3-D) statistical 'atomistic' simulation study of fluctuation-resistant sub 0.1-μm MOSFET architectures with epitaxial channels and delta doping is presented. The need for enhancing the fluctuation resistance of the sub-0.1-μm generation transistors is highlighted by presenting summarized results from atomistic simulations of a wide range of conventional devices with uniformly doped channels. According to our atomistic results, the doping concentration dependence of the random dopant-induced threshold voltage fluctuations in conventional devices is stronger than the analytically predicted fourth-root dependence. As a result of this, the scaling of such devices will be restricted by the �intrinsic� random dopant-induced fluctuations earlier than anticipated. Our atomistic simulations confirm that the introduction of a thin epitaxial layer in the MOSFET's channel can efficiently suppress the random dopant-induced threshold voltage fluctuations in sub-0.1-μm devices. For the first time, we observe an �anomalous� reduction in the threshold voltage fluctuations with an increase in the doping concentration behind the epitaxial channel, which we attribute to screening effects. Also, for the first time we study the effect of a delta doping, positioned behind the epitaxial layer, on the intrinsic threshold voltage fluctuations. Above a certain thickness of epitaxial layer, we observe a pronounced anomalous decrease in the threshold voltage fluctuation with the increase of the delta doping. This phenomenon, which is also associated with screening, enhances the importance of the delta doping in the design of properly scaled fluctuation-resistant sub-0.1-μm MOSFET's

Large-amplitude electron-acoustic solitons in a dusty plasma with kappa-distributed electrons

The Sagdeev pseudopotential method is used to investigate the occurrence and the dynamics of fully nonlinear electrostatic solitary structures in a plasma containing suprathermal hot electrons, in the presence of massive charged dust particles in the background. The soliton existence domain is delineated, and its parametric dependence on different physical parameters is clarified.Comment: 3 pages, 1 figure, presented as a poster at the 6th International Conference on the Physics of Dusty Plasmas (ICPDP6), Garmisch-Partenkirchen, Germany, 201

Hierarchical approach to 'atomistic' 3-D MOSFET simulation

We present a hierarchical approach to the 'atomistic' simulation of aggressively scaled sub-0.1-μm MOSFETs. These devices are so small that their characteristics depend on the precise location of dopant atoms within them, not just on their average density. A full-scale three-dimensional drift-diffusion atomistic simulation approach is first described and used to verify more economical, but restricted, options. To reduce processor time and memory requirements at high drain voltage, we have developed a self-consistent option based on a solution of the current continuity equation restricted to a thin slab of the channel. This is coupled to the solution of the Poisson equation in the whole simulation domain in the Gummel iteration cycles. The accuracy of this approach is investigated in comparison to the full self-consistent solution. At low drain voltage, a single solution of the nonlinear Poisson equation is sufficient to extract the current with satisfactory accuracy. In this case, the current is calculated by solving the current continuity equation in a drift approximation only, also in a thin slab containing the MOSFET channel. The regions of applicability for the different components of this hierarchical approach are illustrated in example simulations covering the random dopant-induced threshold voltage fluctuations, threshold voltage lowering, threshold voltage asymmetry, and drain current fluctuations

Effect of hyperthermia on prognosis after acute ischemic stroke

<p><b>Background and Purpose:</b> Experimental studies have shown that hyperthermia is a determinant of poor outcome after ischemic stroke. Clinical studies evaluating the effect of temperature on poststroke outcome have, however, been limited by small sample sizes. We sought to evaluate the effect of temperature and timing of hyperthermia on outcome after ischemic stroke.</p> <p><b>Methods:</b> Data of 5305 patients in acute stroke trials from the Virtual International Stroke Trials Archive (VISTA) data set were analyzed. Data for temperatures at baseline, eighth, 24th, 48th, and 72nd hours, and seventh day were assessed in relation to outcome (poor versus good) based on the modified Rankin Scale at 3 months. Hyperthermia was defined as temperature >37.2°C and poor outcome as 90-day modified Rankin Scale >2. Hazard ratios with 95% CIs were reported for hyperthermia in relation to the outcome. Logistic regression models, in relation to hyperthermia, were fitted for a set of preselected covariates at different time points to identify predictors/determinants of hyperthermia.</p> <p><b>Results:</b> The average age of patients was 68.0±11.9 years, 2380 (44.9%) were females, and 42.3% (2233) received thrombolysis using recombinant tissue plasminogen activator. After adjustment, hyperthermia was a statistically significant predictor of poor outcome. The hazard ratios (95% CI) for poor outcome in relation to hyperthermia at different time points were: baseline 1.2 (1.0 to 1.4), eighth hour 1.7 (1.2 to 2.2), 24th hour 1.5 (1.2 to 1.9), 48th hour 2.0 (1.5 to 2.6), 72nd hour 2.2 (1.7 to 2.9), and seventh day 2.7 (2.0 to 3.8). Gender, stroke severity (National Institutes of Health Stroke Scale score >16), white blood cell count, and antibiotic use were significantly associated with hyperthermia (P≤0.01).</p> <p><b>Conclusions:</b> Hyperthermia, in acute ischemic stroke, is associated with a poor clinical outcome. The later the hyperthermia occurs within the first week, the worse the prognosis. Severity of stroke and inflammation are important determinants of hyperthermia after ischemic stroke. In patients with acute ischemic stroke, aggressive measures to prevent and treat hyperthermia could improve the clinical outcomes.</p&gt

Economic co-operation in South Asia: The Dilemma of SAFTA and beyond

This paper attempts to evaluate the Pareto optimality of SAFTA for all the member states. Besides, the welfare optimality of three other alternative sets of coordinated trade policies that go beyond SAFTA has also been studied here. These include (a) extended preferential trading between SAFTA and three other major trading blocs (ASEAN, NAFTA and EU27), (b) coordinated full trade liberalisation (carried out unilaterally or as part of a multilateral agreement) by South Asian countries, and (c) SAFTA plus a customs union (two variants with 5 and 10 CET). The analysis, using the standard static GTAP model, shows that the welfare basis for establishing SAFTA or for deeper trade policy coordination is not very strong. Nor is it obvious that cooperation among the South Asia would be forthcoming given the anticipated welfare impacts.

The Multigeneic _Rhg1_ Locus: A Model For The Effects on Root Development, Nematode Resistance and Recombination Suppression.

Soybean (Glycine max L. Merr.) resistance to populations (HgType) of _Heterodera glycines I._, the soybean cyst nematode (SCN), requires a functional allele at rhg1. An apoptosis-like response in the giant cells formed around the nematode results 24-48 h after feeding commences. This study aimed to identify the role of the three genes within the rhg1 locus, a receptor like kinase (RLK), a laccase and an ion anti-porter. Used were near isogeneic lines (NILs) that contrasted at their rhg1 alleles. Features of the rhg1 locus, the candidate genes and their nascent transcripts and proteins in roots were elucidated. First, evidence for a syntenic gene cluster was found and the effectiveness of SNP probes for distinguishing the homeolog sequence variant on linkage group (Lg) B1 from alleles at the rhg1 locus on Lg G was shown. Analysis of plant s heterozygous at rhg1 showed that the allele for resistance was dominant. The absence of recombination events among the NILs between the RLK and other 2 genes eliminated the possibility of a monogeneic rhg1 locus. Finally, an effect on root development was discovered. A model for multigeneic resistance based on developmental control of root growth including a mechanism for segregation distortion is presented

Rationalising racial inequality: ideology, hegemony and post-racialism among the Black and South Asian middle classes

Drawing upon 38 qualitative interviews with Black and South Asian middle-class individuals we theorise post-racialism as a hegemonic ideology. While research tends to focus on how racialised people experience racial inequality, some of our participants rationalised such inequality through a post-racial understanding. This post-racial understanding involves commitments to racial progress and transcendence, the view that racism is no longer a societal issue; race-neutral universalism, the belief that we live in a colourblind meritocracy; and a moral equivalence between anti-racism and anti-racialism, allowing for forms of ‘cultural’ racial prejudice. We examine how these components of post-racialism travel from the political macro-ideological level, to the micro-phenomenological level. Through this analysis we argue that these post-racial rationalisations are not the result of false consciousness, but reflect how post-racialism, as a hegemonic ideology, can manifest itself as common-sense and consistent with particular individuals’ histories of mobility and success