Roses at Twilight

https://digitalcommons.library.umaine.edu/mmb-vp/6146/thumbnail.jp

Thermoelectric three-terminal hopping transport through one-dimensional nanosystems

A two-site nanostructure (e.g, a "molecule") bridging two conducting leads and connected to a phonon bath is considered. The two relevant levels closest to the Fermi energy are connected each to its lead. The leads have slightly different temperatures and chemical potentials and the nanos- tructure is also coupled to a thermal (third) phonon bath. The 3 x 3 linear transport ("Onsager") matrix is evaluated, along with the ensuing new figure of merit, and found to be very favorable for thermoelectric energy conversion.Comment: Accepted by Phys. Rev.

Shadow kernels: A general mechanism for kernel specialization in existing operating systems

Existing operating systems share a common kernel text section amongst all processes. It is not possible to perform kernel specialization or tuning such that different applications execute text optimized for their kernel use despite the benefits of kernel specialization for performance guided optimization, exokernels, kernel fastpaths, and cheaper hardware access. Current specialization primitives involve system wide changes to kernel text, which can have adverse effects on other processes sharing the kernel due to the global side-effects. We present shadow kernels: a primitive that allows multiple kernel text sections to coexist in a contemporary operating system. By remapping kernel virtual memory on a context-switch, or for individual system calls, we specialize the kernel on a fine-grained basis. Our implementation of shadow kernels uses the Xen hypervisor so can be applied to any operating system that runs on Xen.This work was principally supported by internal funds from the Computer Laboratory at the University of Cambridge; and also by the Engineering and Physical Sciences Research Council [grant number EP/K503009/1].This is the final version of the article. It first appeared from ACM via http://dx.doi.org/10.1145/2797022.279702

Filtering and analyzing mobile qubit information via Rashba-Dresselhaus-Aharonov-Bohm interferometers

Spin-1/2 electrons are scattered through one or two diamond-like loops, made of quantum dots connected by one-dimensional wires, and subject to both an Aharonov-Bohm flux and (Rashba and Dresselhaus) spin-orbit interactions. With some symmetry between the two branches of each diamond, and with appropriate tuning of the electric and magnetic fields (or of the diamond shapes) this device completely blocks electrons with one polarization, and allows only electrons with the opposite polarization to be transmitted. The directions of these polarizations are tunable by these fields, and do not depend on the energy of the scattered electrons. For each range of fields one can tune the site and bond energies of the device so that the transmission of the fully polarized electrons is close to unity. Thus, these devices perform as ideal spin filters, and these electrons can be viewed as mobile qubits; the device writes definite quantum information on the spinors of the outgoing electrons. The device can also read the information written on incoming polarized electrons: the charge transmission through the device contains full information on this polarization. The double-diamond device can also act as a realization of the Datta-Das spin field-effect transistor.Comment: 13 pages, 8 figure

Lake Ontario Long Term Biological Monitoring Program: 1981, 1982 Data Base

The Bioindex, or Long Term Biological Monitoring Program, was developed to: 1) determine normal seasonal patterns and annual ranges of abundance, community structure, and when possible, productivity of the biological components - phytoplankton, zooplankton, and benthos; 2) relate the biological components to variations in the physical, nutrient, and biological environment; and, 3) assess the adopted sampling strategy for long term monitoring. The data bases from the first two years are summarized in this document

Clinically Important Deterioration (CID) and Ageing in COPD: A Systematic Review and Meta-Regression Analysis According to PRISMA Statement

purpose: clinically important deterioration (CID) is a composite endpoint developed to quantify the impact of pharmacological treatment in clinical trials for chronic obstructive pulmonary disease (COPD), also showing a prognostic value. CID is defined as any of the following condition: forced expiratory volume in 1 s decrease ≥100 mL from baseline, and/or St. george's respiratory questionnaire total score increase ≥4-unit from baseline, and/or the occurrence of a moderate-to-severe exacerbation of COPD. although most COPD patients experience a clinical worsening as they get older, to date, no specific studies assessed the correlation between ageing and CID in COPD. therefore, the aim of this study was to investigate the impact of ageing on CID in COPD patients. patients and methods: data obtained from 55219 COPD patients were extracted from 17 papers, mostly post-hoc analyses. a pairwise meta-analysis and a meta-regression analysis were performed according to PRISMA-P guidelines to quantify the impact of pharmacological therapy on CID and to determine whether ageing might modulate the risk of CID in COPD patients. results: Inhaled treatments resulted generally effective in reducing the risk of CID in COPD (relative risk: 0.81, 95% confidence interval 0.79-0.84; P < 0.001). the meta-regression analysis indicated a trend toward significance (P = 0.063) in the linear relationship between age and the risk of CID. Of note, age significantly (P < 0.05) increased the risk of CID when associated with lower post-bronchodilator FEV1. these results were not affected by a significant risk of bias. conclusion: this quantitative synthesis suggests that inhaled therapy is effective in reducing the risk of CID in COPD, although such a protective effect may be affected in older patients with impaired lung function. further studies specifically designed on CID in COPD are needed to confirm these results

Soroban: Attributing latency in virtualized environments

Applications running in the cloud have highly-variable response times due to the lack of perfect performance isolation from other services served by common infrastructure. In particular, response latency when executing on a loaded hypervisor or in a container is substantially higher than uncontested bare-metal performance. Whilst efforts to increase performance isolation continue, we present Soroban, a framework for attributing latency to either the cloud provider or their customer. Soroban allows cloud providers to instrument commonly used programs, such as a web server to determine, for each request, how much of the latency is due to the cloud provider, or the consumer. We apply Soroban to a HTTP server and show that it identifies when the cause of latency is due to a provider-induced activity, such as underprovisioning a host, or due to the software run by the customer.This is the author accepted manuscript. The final version is available from USENIX. via https://www.usenix.org/conference/hotcloud15/workshop-program/presentation/sne