Improving Non-Volatile Memory Lifetime through Temporal Wear-Limiting

Non-volatile memory technologies provide a low-power, high-density alternative to traditional DRAM main memories, yet all suffer from some degree of limited write endurance. The non-uniformity of write traffic exacerbates this limited endurance, causing write-induced wear to concentrate on a few specific lines. Wear-leveling attempts to mitigate this issue by distributing write-induced wear uniformly across the memory. Orthogonally, wear-limiting attempts to increase memory lifetime by directly reducing wear. In this paper, we present the concept of temporal wear-limiting, in which we exploit the trade-off between write latency and memory lifetime. Using a history of the slack between per-bank write operations, we predict future write latency, allowing for up to a 1.5x memory lifetime improvement. We present two extensions for improving the effectiveness of this history-based mechanism: a method for dynamically determining the optimum history size, and a method for increasing lifetime improvement through address prediction

Aqueous hydrocarbon systems: Experimental measurements and quantitative structure-property relationship modeling

Scope and Method of Study: The experimental objectives of this work were to (a) evaluate existing mutual hydrocarbon-water liquid-liquid equilibrium (LLE) data, and (b) develop an experimental apparatus capable of measuring accurately the hydrocarbon-water (LLE) mutual solubilities. The hydrocarbon-water systems studied included benzene-water, toluene-water, and 3-methylpentane water. The modeling efforts in this study focused on developing quantitative structure-property relationship (QSPR) models for the prediction of infinite-dilution activity coefficient values (gamma infinity i) of hydrocarbon-water systems. Specifically, case studies were constructed to investigate the efficacy of (a) QSPR models using multiple linear regression analyses and non-linear neural networks; and (b) theory-based QSPR model, where the Bader-Gasem activity coefficient model derived from a modified Peng-Robinson equation of state (EOS) is used to model the phase behavior, and QSPR neural networks are used to generalize the EOS binary interaction parameters. The database used in the modeling efforts consisted of 1400 infinite-dilution activity coefficients at temperatures ranging from 283 K to 373 K.Findings and Conclusions: A continuous flow apparatus was utilized to measure the LLE mutual solubilities at temperatures ranging from ambient to 500 K, which is near the three-phase critical end point of the benzene-water and toluene-water systems. The well-documented benzene-water system was used to validate the reliability of the sampling and analytical techniques employed. Generally, adequate agreement was observed for the benzene-water, toluene-water, and 3-methylpentane-water systems with literature data. An error propagation analysis for the three systems indicated maximum expected uncertainties of 4% and 8% in the water phase and organic phase solubility measurements, respectively. In general, the use of non-linear QSPR models developed in this work were satisfactory and compared favorably to the majority of predictive models found in literature; however, these model did not account for temperature dependence. The Bader-Gasem activity coefficient model fitted with QSPR generalized binary interactions was capable of providing accurate predictions for the infinite-dilution activity coefficients of hydrocarbons in water. Careful validation of the model predictions over the full temperature range of the data considered yielded absolute average deviations of 3.4% in ln gamma infinity i and 15% in gamma infinity i, which is about twice the estimated experimental uncertainty. This study provides valuable LLE mutual solubility data and further demonstrates the effectiveness of theory-framed QSPR modeling of thermophysical properties

Scaling dynamics of the ultracold Bose gas

The large-scale expansion dynamics of quantum gases is a central tool for ultracold gas experiments and poses a significant challenge for theory. In this work we provide an exact reformulation of the Gross-Pitaevskii equation for the ultracold Bose gas in a coordinate frame that adaptively scales with the system size during evolution, enabling simulations of long evolution times during expansion or similar large-scale manipulation. Our approach makes no hydrodynamic approximations, is not restricted to a scaling ansatz, harmonic potentials, or energy eigenstates, and can be generalized readily to non-contact interactions via the appropriate stress tensor of the quantum fluid. As applications, we simulate the expansion of the ideal gas, a cigar-shaped condensate in the Thomas-Fermi regime, and a linear superposition of counter propagating Gaussian wavepackets. We recover known scaling for the ideal gas and Thomas-Fermi regimes, and identify a linear regime of aspect-ratio preserving free expansion; analysis of the scaling dynamics equations shows that an exact, aspect-ratio invariant, free expansion does not exist for nonlinear evolution. Our treatment enables exploration of nonlinear effects in matter-wave dynamics over large scale-changing evolution.Comment: 12 pages, 3 figures, 2 appendice

Context-induced Contrast and Assimilation in Judging Supportiveness

Social support research increasingly draws from research on social cognition. Most of this research has studied assimilation and chronically accessible (i.e., frequently activated) social support constructs. This article presents three studies, in both laboratory and treatment settings, on context-induced contrast and assimilation in support judgments. In each study, participants exposed to positive social contexts subsequently rated supportive stimuli more negatively than participants exposed to negative social contexts. These effects were observed in ratings of participants’ own social networks, the social climate of a residential treatment environment, and a videotaped supportive interaction. In two studies, negative contexts also were associated with increased negative affect and affect-related assimilation. That is, participants with more negative affect rated social environments more negatively than participants with less negative emotion. In some circumstances, context- induced contrast and assimilation counteracted each other. These effects have implications for social support interventions

Vortex Formation by Interference of Multiple Trapped Bose-Einstein Condensates

We report observations of vortex formation as a result of merging together multiple $^{87}$Rb Bose-Einstein condensates (BECs) in a confining potential. In this experiment, a trapping potential is partitioned into three sections by a barrier, enabling the simultaneous formation of three independent, uncorrelated condensates. The three condensates then merge together into one BEC, either by removal of the barrier, or during the final stages of evaporative cooling if the barrier energy is low enough; both processes can naturally produce vortices within the trapped BEC. We interpret the vortex formation mechanism as originating in interference between the initially independent condensates, with indeterminate relative phases between the three initial condensates and the condensate merging rate playing critical roles in the probability of observing vortices in the final, single BEC.Comment: 5 pages, 3 figure

Inactivation of HIV-1 in breast milk by treatment with the alkyl sulfate microbicide sodium dodecyl sulfate (SDS)

BACKGROUND: Reducing transmission of HIV-1 through breast milk is needed to help decrease the burden of pediatric HIV/AIDS in society. We have previously reported that alkyl sulfates (i.e., sodium dodecyl sulfate, SDS) are microbicidal against HIV-1 at low concentrations, are biodegradable, have little/no toxicity and are inexpensive. Therefore, they may be used for treatment of HIV-1 infected breast milk. In this report, human milk was artificially infected by adding to it HIV-1 (cell-free or cell-associated) and treated with ≤1% SDS (≤10 mg/ml). Microbicidal treatment was at 37°C or room temperature for 10 min. SDS removal was performed with a commercially available resin. Infectivity of HIV-1 and HIV-1 load in breast milk were determined after treatment. RESULTS: SDS (≥0.1%) was virucidal against cell-free and cell-associated HIV-1 in breast milk. SDS could be substantially removed from breast milk, without recovery of viral infectivity. Viral load in artificially infected milk was reduced to undetectable levels after treatment with 0.1% SDS. SDS was virucidal against HIV-1 in human milk and could be removed from breast milk if necessary. Milk was not infectious after SDS removal. CONCLUSION: The proposed treatment concentrations are within reported safe limits for ingestion of SDS by children of 1 g/kg/day. Therefore, use of alkyl sulfate microbicides, such as SDS, to treat HIV1-infected breast milk may be a novel alternative to help prevent/reduce transmission of HIV-1 through breastfeeding

Cost-Benefit Analysis Comparing Trough, Two-Level AUC, and Bayesian AUC Dosing for Vancomycin\u27: Authors\u27 Reply

Our response to your letter will address the two primary concerns in sequential order: the first concern being the Bayesian AUC to trough comparison, and the second being two-level AUC to trough