On the Impact of Performance Faults in Modern Microprocessors

Modern microprocessors incorporate a variety of architectural features, such as branch prediction and speculative execution, which are not critical to the correctness of their operation yet are essential towards improving performance. Accordingly, while faults in the corresponding hardware may not necessarily affect functional correctness, they may, nevertheless, adversely impact performance. In this paper, we investigate quantitatively the performance impact of such faults using a superscalar, dynamically-scheduled, out-of-order, Alpha-like microprocessor, on which we execute SPEC2000 integer benchmarks. We provide extensive fault simulation-based experimental results that elucidate the various aspects of performance faults and we discuss how this information may guide the inclusion of additional hardware for performance loss recovery and yield enhancement.     

Mental health services in Louisiana school-based health centers post-Hurricanes Katrina and Rita.

Following Hurricanes Katrina and Rita, Louisiana school-based health centers (SBHCs) were called on to respond to a sharp increase in mental health needs, especially for displaced students coping with grief, loss, trauma, and uncertainty. To assess the impact of the hurricanes on the students and the needs of SBHC mental health providers (MHPs), we surveyed MHPs in each of the SBHCs under the auspices of the Louisiana Department of Health and Hospitals, Office of Public Health. SBHC practitioners from around the state reported that mental health service utilization rose during the 2005-2006 school year, but utilization of services increased most significantly in schools receiving the majority of displaced students. Anxiety and adjustment problems were noted as increasing the most following the hurricanes. A multitude of other conditions was also reported. By the time of this survey in April 2006, the reported prevalence of most symptoms had declined, but all remained above their pre-hurricane levels. Self-reported needs of SBHC MHPs are also discussed in light of the major natural disasters. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Surface modification of commercial carbon black by silane coupling agents for improving dispersibility in rubber compounds

The dispersion of a filler in a rubber matrix is a crucial parameter affecting the mechanical and dynamical properties of a rubber compound. It is the current issue of the rubber compounding industry because, most fillers are categorized as a mineral, while the rubber is an organic material. The surface modification of the filler has been accepted as an effective technique for the improvement of the abovementioned parameter. First, the surface premodification of commercial carbon black with a grade of N660 (CB) was implemented by four different oxidation methods. After that, among of used methods, the oxidation method using citric acid was selected to produce modified carbon black (CB-Oxi) for further treatment. Subsequently, the coupling agent, Bis[3-(triethoxysilyl)propyl] tetrasulfide (TESPT) was functionalized on the surface of CB-Oxi to produce modified-CB-Oxi. Also, for comparison purposes, the TESPT functionalization was accomplished on untreated CB to form modified-CB. The FTIR spectra of CB-Oxi showed using the premodification method introduced the hydroxyl and carboxyl groups on the surface of CB. The correspondent spectra for modified-CB-Oxi confirmed the existence of silane groups on the surface of the carbon black. However, the mentioned silane groups were not observed on the surface of modified-CB. The findings were strengthened by several characteristic techniques including, FESEM, XRD, EDS, CHNS elemental analysis, and RAMAN spectra. The FESEM graphs and elemental mapping showed homogeneous dispersion and uniform distribution of sulfur and silicon elements on the modified-CB-Oxi surface. According to RAMAN spectra, the disturbance in the structure of carbon black graphite was reduced after surface modification. modified-CB-Oxi is proposed as a potential substitute filler for current commercial carbon black in rubber compounding.     

Biomimetic Natural Killer Membrane Camouflaged Polymeric Nanoparticle for Targeted Bioimaging

In the present study, a biomimetic nanoconstruct (BNc) with a multimodal imaging system is engineered using tumor homing natural killer cell membrane (NKM), near‐infrared (NIR) fluorescent dye, and gadolinium (Gd) conjugate‐based magnetic resonance imaging contrast agent onto the surface of a polymeric nanoparticle. The engineered BNc is 110 ± 20 nm in size and showed successful retention of NKM proteins. The magnetic properties of the BNc are found to be tunable from 2.1 ± 0.17 to 5.3 ± 0.5 mm ^?1 s^?1 under 14.1 T, by adjusting the concentration of Gd‐lipid conjugate onto the surface of the BNc. Confocal imaging and cell sorting analysis reveal a distinguishable cellular interaction of the BNc with MCF‐7 cells in comparison to that of bare polymeric nanoparticles suggesting the tumor homing properties of NKM camouflage system. The in vitro cellular interaction results are further confirmed by in vivo NIR fluorescent tumor imaging and ex vivo MR imaging, respectively. Pharmacokinetics and biodistribution analysis of the BNc show longer circulation half‐life (≈9.5 h) and higher tumor accumulation (10% of injected dose) in MCF‐7 induced tumor‐bearing immunodeficient NU/NU nude mice. Owing to the proven immunosurveillance potential of NK‐cell in the field of immunotherapy, the BNc engineered herein would hold promises in the design consideration of nanomedicine engineering.     

A hybrid discontinuous spectral element method and filtered mass density function solver for turbulent reacting flows

Abstract

We present a novel hybrid scheme for the large eddy simulation (LES) of turbulent reacting flows. The scheme couples the discontinuous spectral element method (DSEM) solver for the unsteady compressible Navier-Stokes equations with a Monte Carlo particle filtered mass density function (FMDF) solver for the transport of reacting species. The method is capable of high-order simulations on unstructured grids. Mean particle estimate construction mimics the DSEM numerical procedure and utilizes variable basis functions. The scheme is tested on non-reacting and reacting Taylor-Green vortex flows. Studies of varying polynomial order, different basis functions for constructing particle estimates, and varying particle quantities are conducted. We demonstrate that a tent kernel, in conjunction with high polynomial order, produces the most accurate results. The chemically reacting simulations validate the hybrid scheme and demonstrate its applicability across a range of reaction regimes. The hybrid scheme's computational cost is 2.1 times the DSEM-LES solver.     

Validated Growth Rate-Dependent Regulation of Lipid Metabolism in Yarrowia lipolytica

Given the strong potential of Yarrowia lipolytica to produce lipids for use as renewable fuels and oleochemicals, it is important to gain in-depth understanding of the molecular mechanism underlying its lipid accumulation. As cellular growth rate affects biomass lipid content, we performed a comparative proteomic analysis of Y. lipolytica grown in nitrogen-limited chemostat cultures at different dilution rates. After confirming the correlation between growth rate and lipid accumulation, we were able to identify various cellular functions and biological mechanisms involved in oleaginousness. Inspection of significantly up- and downregulated proteins revealed nonintuitive processes associated with lipid accumulation in this yeast. This included proteins related to endoplasmic reticulum (ER) stress, ER–plasma membrane tether proteins, and arginase. Genetic engineering of selected targets validated that some genes indeed affected lipid accumulation. They were able to increase lipid content and were complementary to other genetic engineering strategies to optimize lipid yield.     

High-purity hydrogen production by sorption-enhanced methanol steam reforming over a combination of Cu–Zn–CeO2–ZrO2/MCM-41 catalyst and (Li–Na–K) NO3·MgO adsorbent

In this study, sorption-enhanced methanol steam reforming (SEMSR) was applied to generate high-purity hydrogen. The mesoporous MCM-41 as support and CuO, ZnO, CeO₂, ZrO₂ as active agents and promoters were employed for the catalyst preparation. In addition, (Li–Na–K) NO₃·MgO as a CO₂ adsorbent was prepared by the wet mixing method. The fresh and used catalysts were characterized by XRD, BET, FTIR, FESEM, TEM, H₂-TPR and TGA analyses. Also, the CO₂ sorbent was studied by XRD, BET, FESEM, TEM and TGA analyses before and after the reaction. The SEMSR performances of the synthesized catalyst and adsorbent were evaluated experimentally in a fixed-bed reactor. The effect of various conditions such as temperature, WHSV, feed molar ratio and sorbent/catalyst ratio were investigated. The best results were obtained at 300 °C, a feed molar ratio (water/methanol) of 2:1, a WHSV of 1.62 h^?1, and the sorbent/catalyst ratio of 8:1, which produced 99.8% hydrogen, 25% more than the hydrogen production during conventional methanol steam reforming. Moreover, the cyclic stability of the catalyst and the sorbent was studied for 10 cycles.     

The structure and the small-scale intermittency of passive scalars in homogeneous turbulence

Results generated by direct numerical simulations (DNS) are used to study the structure and the small-scale intermittency of a passive scalar contaminant in a homogeneous turbulent shear flow. Simulations are conducted of flows with and without a constant mean scalar gradient. In all cases, the probability density functions (PDFs) of the scalars adopt an approximate gaussian distribution at the final stages of mixing. In the presence of the mean gradient, the scalar fields yield a nearly identical asymptotic state independent of initial conditions. In these cases, the gradient of the fluctuating scalar field shows preferred directions of orientation with respect to the strain eigenvectors; and the mean transverse velocity conditioned on the scalar is linear. These fields also portray increased flatness and skewness of the scalar-difference field as the separation distance becomes small. Larger than gaussian tails are observed in the PDF of both the velocity- and the scalar-derivatives, and the intermittency of the scalar derivative is shown to be more pronounced in the presence of the mean scalar gradient. Conditional averages of the angle between the scalar gradient and the strain eigenvectors suggest that the scalar field may be viewed as a random gaussian background field superimposed with sporadic scalar structures which are responsible for intermittency. With this view, a Langevin transport equation is proposed for the mapping of the scalar derivative PDF from a gaussian reference field. This is done in the context of the two-fluid model of She (1990). With this model, the PDF of the scalar dissipation is produced and the results are compared with DNS data.     

Novel Bayesian Additive Regression Tree Methodology for Flood Susceptibility Modeling

Water Resources Management - Identifying areas prone to flooding is a key step in flood risk management. The purpose of this study is to develop and present a novel flood susceptibility model based...