672 research outputs found
Plasma variables and tribological properties of coatings in low pressure (0.1 - 10.0 torr) plasma systems
A detailed treatment is presented of the dialog known as plasma surface interactions (PSI) with respect to the coating process and its tribological behavior. Adsorption, morphological changes, defect formation, sputtering, chemical etching, and secondary electron emission are all discussed as promoting and enhancing the surface chemistry, thus influencing the tribological properties of the deposited flux. Phenomenological correlations of rate of deposition, flux composition, microhardness, and wear with the plasma layer variables give an insight to the formation of chemical bonding between the deposited flux and the substrate surface
Fine-Grain Checkpointing with In-Cache-Line Logging
Non-Volatile Memory offers the possibility of implementing high-performance,
durable data structures. However, achieving performance comparable to
well-designed data structures in non-persistent (transient) memory is
difficult, primarily because of the cost of ensuring the order in which memory
writes reach NVM. Often, this requires flushing data to NVM and waiting a full
memory round-trip time.
In this paper, we introduce two new techniques: Fine-Grained Checkpointing,
which ensures a consistent, quickly recoverable data structure in NVM after a
system failure, and In-Cache-Line Logging, an undo-logging technique that
enables recovery of earlier state without requiring cache-line flushes in the
normal case. We implemented these techniques in the Masstree data structure,
making it persistent and demonstrating the ease of applying them to a highly
optimized system and their low (5.9-15.4\%) runtime overhead cost.Comment: In 2019 Architectural Support for Programming Languages and Operating
Systems (ASPLOS 19), April 13, 2019, Providence, RI, US
Cost–benefit of infection control interventions targeting methicillin-resistant Staphylococcus aureus in hospitals: systematic review
AbstractInfections caused by methicillin-resistant Staphylococcus aureus (MRSA) incur significant costs. We aimed to examine the cost and cost-benefit of infection control interventions against MRSA and to examine factors affecting economic estimates. We performed a systematic review of studies assessing infection control interventions aimed at preventing spread of MRSA in hospitals and reporting intervention costs, savings, cost-benefit or cost-effectiveness. We searched PubMed and references of included studies with no language restrictions up to January 2012. We used the Quality of Health Economic Studies tool to assess study quality. We report cost and savings per month in 2011 US per month; median savings were 38 751 (IQR 14 206–75 842) US$ per month (23 studies). Higher save/cost ratios were observed in the intermediate to high endemicity setting compared with the low endemicity setting, in hospitals with <500-beds and with interventions of >6 months. Infection control intervention to reduce spread of MRSA in acute-care hospitals showed a favourable cost/benefit ratio. This was true also for high MRSA endemicity settings. Unresolved economic issues include rapid screening using molecular techniques and universal versus targeted screening
Corticosteroids for pneumonia
BackgroundPneumonia is a common and potentially serious illness. Corticosteroids have been suggested for the treatment of different types of infection, however their role in the treatment of pneumonia remains unclear. This is an update of a review published in 2011.ObjectivesTo assess the efficacy and safety of corticosteroids in the treatment of pneumonia.Search methodsWe searched the Cochrane Acute Respiratory Infections Group's Specialised Register, CENTRAL, MEDLINE, Embase, and LILACS on 3March 2017, together with relevant conference proceedings and references of identified trials. We also searched three trials registers for ongoing and unpublished trials.Selection criteriaWe included randomised controlled trials (RCTs) that assessed systemic corticosteroid therapy, given as adjunct to antibiotic treatment, versus placebo or no corticosteroids for adults and children with pneumonia.Data collection and analysisWe used standard methodological procedures expected by Cochrane. Two review authors independently assessed risk of bias and extracted data. We contacted study authors for additional information. We estimated risk ratios (RR) with 95% confidence intervals (CI) and pooled data using the Mantel-Haenszel fixed-effect model when possible.Main resultsWe included 17 RCTs comprising a total of 2264 participants; 13 RCTs included 1954 adult participants, and four RCTs included 310 children. This update included 12 new studies, excluded one previously included study, and excluded five new trials. One trial awaits classification.All trials limited inclusion to inpatients with community-acquired pneumonia (CAP), with or without healthcare-associated pneumonia (HCAP). We assessed the risk of selection bias and attrition bias as low or unclear overall. We assessed performance bias risk as low for nine trials, unclear for one trial, and high for seven trials. We assessed reporting bias risk as low for three trials and high for the remaining 14 trials.Corticosteroids significantly reduced mortality in adults with severe pneumonia (RR 0.58, 95% CI 0.40 to 0.84; moderate-quality evidence), but not in adults with non-severe pneumonia (RR 0.95, 95% CI 0.45 to 2.00). Early clinical failure rates (defined as death from any cause, radiographic progression, or clinical instability at day 5 to 8) were significantly reduced with corticosteroids in people with severe and non-severe pneumonia (RR 0.32, 95% CI 0.15 to 0.7; and RR 0.68, 95% CI 0.56 to 0.83, respectively; high-quality evidence). Corstocosteroids reduced time to clinical cure, length of hospital and intensive care unit stays, development of respiratory failure or shock not present at pneumonia onset, and rates of pneumonia complications.Among children with bacterial pneumonia, corticosteroids reduced early clinical failure rates (defined as for adults, RR 0.41, 95% CI 0.24 to 0.70; high-quality evidence) based on two small, clinically heterogeneous trials, and reduced time to clinical cure.Hyperglycaemia was significantly more common in adults treated with corticosteroids (RR 1.72, 95% CI 1.38 to 2.14). There were no significant differences between corticosteroid-treated people and controls for other adverse events or secondary infections (RR 1.19, 95% CI 0.73 to 1.93).Authors' conclusionsCorticosteroid therapy reduced mortality and morbidity in adults with severe CAP; the number needed to treat for an additional beneficial outcome was 18 patients (95% CI 12 to 49) to prevent one death. Corticosteroid therapy reduced morbidity, but not mortality, for adults and children with non-severe CAP. Corticosteroid therapy was associated with more adverse events, especially hyperglycaemia, but the harms did not seem to outweigh the benefits
LNCS
In resource allocation games, selfish players share resources that are needed in order to fulfill their objectives. The cost of using a resource depends on the load on it. In the traditional setting, the players make their choices concurrently and in one-shot. That is, a strategy for a player is a subset of the resources. We introduce and study dynamic resource allocation games. In this setting, the game proceeds in phases. In each phase each player chooses one resource. A scheduler dictates the order in which the players proceed in a phase, possibly scheduling several players to proceed concurrently. The game ends when each player has collected a set of resources that fulfills his objective. The cost for each player then depends on this set as well as on the load on the resources in it – we consider both congestion and cost-sharing games. We argue that the dynamic setting is the suitable setting for many applications in practice. We study the stability of dynamic resource allocation games, where the appropriate notion of stability is that of subgame perfect equilibrium, study the inefficiency incurred due to selfish behavior, and also study problems that are particular to the dynamic setting, like constraints on the order in which resources can be chosen or the problem of finding a scheduler that achieves stability
Supernova dust for the extinction law in a young infrared galaxy at z = 1
We apply the supernova(SN) extinction curves to reproduce the observed
properties of SST J1604+4304 which is a young infrared (IR) galaxy at z = 1.
The SN extinction curves used in this work were obtained from models of unmixed
ejecta of type II supernovae(SNe II) for the Salpeter initial mass function
(IMF) with a mass range from 8 to 30 M_sun or 8 to 40 M_sun.
The effect of dust distributions on the attenuation of starlight is
investigated by performing the chi-square fitting method against various dust
distributions. These are the commonly used uniform dust screen, the clumpy dust
screen, and the internal dust geometry. We add to these geometries three
scattering properties, namely, no-scattering, isotropic scattering, and
forward-only scattering. Judging from the chi-square values, we find that the
uniform screen models with any scattering property provide good approximations
to the real dust geometry. Internal dust is inefficient to attenuate starlight
and thus cannot be the dominant source of the extinction.
We show that the SN extinction curves reproduce the data of SST J1604+4304
comparable to or better than the Calzetti extinction curve. The Milky Way
extinction curve is not in satisfactory agreement with the data unless several
dusty clumps are in the line of sight. This trend may be explained by the
abundance of SN-origin dust in these galaxies; SN dust is the most abundant in
the young IR galaxy at z = 1, abundant in local starbursts, and less abundant
in the Galaxy. If dust in SST J1604+4304 is dominated by SN dust, the dust
production rate is about 0.1 M_sun per SN.Comment: 12 pages, 8 figures, 1 tabl
Photometric redshift accuracy in AKARI Deep Surveys
We investigate the photometric redshift accuracy achievable with the AKARI
infrared data in deep multi-band surveys, such as in the North Ecliptic Pole
field. We demonstrate that the passage of redshifted policyclic aromatic
hydrocarbons and silicate features into the mid-infrared wavelength window
covered by AKARI is a valuable means to recover the redshifts of starburst
galaxies. To this end we have collected a sample of ~60 galaxies drawn from the
GOODS-North Field with spectroscopic redshift 0.5<~z_spec<~1.5 and photometry
from 3.6 to 24 micron, provided by the Spitzer, ISO and AKARI satellites. The
infrared spectra are fitted using synthetic galaxy Spectral Energy
Distributions which account for starburst and active nuclei emission. For ~90%
of the sources in our sample the redshift is recovered with an accuracy
|z_phot-z_spec|/(1+z_spec)<~10%. A similar analysis performed on different sets
of simulated spectra shows that the AKARI infrared data alone can provide
photometric redshifts accurate to |z_phot-z_spec|/(1+z_spec)<~10% (1-sigma) at
z<~2. At higher redshifts the PAH features are shifted outside the wavelength
range covered by AKARI and the photo-z estimates rely on the less prominent 1.6
micron stellar bump; the accuracy achievable in this case on (1+z) is ~10-15%,
provided that the AGN contribution to the infrared emission is subdominant. Our
technique is no more prone to redshift aliasing than optical-uv photo-z, and it
may be possible to reduce this aliasing further with the addition of
submillimetre and/or radio data.Comment: 27 pages, 12 figures, 4 tables. Accepted for publication on MNRA
Cosmological evolution of compact AGN at 15 GHz
We study the uniformity of the distribution of compact flat-spectrum AGN on
the sky and the evolution of their relativistic jets with cosmic epoch. A
complete sample of compact extragalactic radio sources at 15 GHz was recently
compiled to conduct the MOJAVE program. The MOJAVE sample comprises 133
radio-loud flat-spectrum AGN with compact relativistic outflows detected at
parsec scales. The source counts of compact AGN shows that the MOJAVE sample
represents a flux-limited complete sample. Analysis of the population of
flat-spectrum quasars of the sample reveals that the pc-scale jets of quasars
have intrinsic luminosities in the range between ~10^24 W/Hz and ~10^27 W/Hz
and Lorentz factors distributed between 3 and 30. We find that the apparent
speed (or Lorentz factor) of jets evolves with redshift, increasing from z~0 to
z~1 and then falling at higher redshifts (z~2.5) by a factor of 2.5. The
evolution of apparent speeds does not affect significantly the evolution of the
beamed luminosity function of quasars, which is most likely to be dependent on
the evolution of radio luminosity. Furthermore, the beamed radio luminosity
function suggests that the intrinsic luminosity function of quasars has a
double power-law form: it is flat at low luminosities and steep at high
luminosities. There is a positive evolution of quasars at low redshifts (z<0.5)
and strong negative evolution at redshifts >1.7 with space density decline up
to z~2.5. This implies that the powerful jets were more populous at redshifts
between 0.5 and 1.7. We show that the evolution of compact quasars is
luminosity dependent and it depends strongly on the speed of the jet suggesting
that there are two distinct populations of quasars with slow and fast jets
which evolve differently with redshift.Comment: 9 pages, 10 figures, accepted for publication in Astronomy &
Astrophysic
No apparent accretion mode changes detected in Cen X-3
The presence of two distinct spectral states has previously been reported for
Cen X-3 on the basis of RXTE/ASM observations. Triggered by this result, we
investigated the spectral properties of the source using the larger amount of
X-ray data now available with the aim to clarify and interpret the reported
behavior. To check the reported results we used the same data set and followed
the same analysis procedures as in the work reporting the two spectral states.
Additionally, we repeated the analysis using the enlarged data sample including
the newest RXTE/ASM observations as well as the data from the MAXI monitor and
from the INTEGRAL/JEM-X and ISGRI instruments. We could not confirm the
reported presence of the two spectral states in Cen X-3 either inComment: 4 pages, 6 figures, article is accepted for Astronomy & Astrophysic
Evolutionarily conserved regulation of hypocretin neuron specification by Lhx9
Loss of neurons that express the neuropeptide hypocretin (Hcrt) has been implicated in narcolepsy, a debilitating disorder characterized by excessive daytime sleepiness and cataplexy. Cell replacement therapy, using Hcrt-expressing neurons generated in vitro, is a potentially useful therapeutic approach, but factors sufficient to specify Hcrt neurons are unknown. Using zebrafish as a high-throughput system to screen for factors that can specify Hcrt neurons in vivo, we identified the LIM homeobox transcription factor Lhx9 as necessary and sufficient to specify Hcrt neurons. We found that Lhx9 can directly induce hcrt expression and we identified two potential Lhx9 binding sites in the zebrafish hcrt promoter. Akin to its function in zebrafish, we found that Lhx9 is sufficient to specify Hcrt-expressing neurons in the developing mouse hypothalamus. Our results elucidate an evolutionarily conserved role for Lhx9 in Hcrt neuron specification that improves our understanding of Hcrt neuron development
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