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High-intensity laser–plasma interactions produce a wide array of energetic particles and beams with promising applications. Unfortunately, the high repetition rate and high average power requirements for many applications are not satisfied by the lasers, optics, targets, and diagnostics currently employed. Here, we aim to address the need for high-repetition-rate targets and optics through the use of liquids. A novel nozzle assembly is used to generate high-velocity, laminar-flowing liquid microjets which are compatible with a low-vacuum environment, generate little to no debris, and exhibit precise positional and dimensional tolerances. Jets, droplets, submicron-thick sheets, and other exotic configurations are characterized with pump–probe shadowgraphy to evaluate their use as targets. To demonstrate a high-repetition-rate, consumable, liquid optical element, we present a plasma mirror created by a submicron-thick liquid sheet. This plasma mirror provides etalon-like anti-reflection properties in the low field of 0.1% and high reflectivity as a plasma, 69%, at a repetition rate of 1 kHz. Practical considerations of fluid compatibility, in-vacuum operation, and estimates of maximum repetition rate are addressed. The targets and optics presented here demonstrate a potential technique for enabling the operation of laser–plasma interactions at high repetition rates.
The B fields in OB stars (BOB) survey is an ESO large programme collecting spectropolarimetric observations for a large number of early-type stars in order to study the occurrence rate, properties, and ultimately the origin of magnetic fields in massive stars. As of July 2014, a total of 98 objects were observed over 20 nights with FORS2 and HARPSpol. Our preliminary results indicate that the fraction of magnetic OB stars with an organised, detectable field is low. This conclusion, now independently reached by two different surveys, has profound implications for any theoretical model attempting to explain the field formation in these objects. We discuss in this contribution some important issues addressed by our observations (e.g., the lower bound of the field strength) and the discovery of some remarkable objects.
A number of copy number variants (CNVs) have been suggested as
susceptibility factors for schizophrenia. For some of these the data
remain equivocal, and the frequency in individuals with schizophrenia is
To determine the contribution of CNVs at 15 schizophrenia-associated loci
(a) using a large new data-set of patients with schizophrenia
(n = 6882) and controls (n = 6316),
and (b) combining our results with those from previous studies.
We used Illumina microarrays to analyse our data. Analyses were
restricted to 520 766 probes common to all arrays used in the different
We found higher rates in participants with schizophrenia than in controls
for 13 of the 15 previously implicated CNVs. Six were nominally
significantly associated (P<0.05) in this new
data-set: deletions at 1q21.1, NRXN1, 15q11.2 and
22q11.2 and duplications at 16p11.2 and the Angelman/Prader–Willi
Syndrome (AS/PWS) region. All eight AS/PWS duplications in patients were
of maternal origin. When combined with published data, 11 of the 15 loci
showed highly significant evidence for association with schizophrenia
We strengthen the support for the majority of the previously implicated
CNVs in schizophrenia. About 2.5% of patients with schizophrenia and 0.9%
of controls carry a large, detectable CNV at one of these loci. Routine
CNV screening may be clinically appropriate given the high rate of known
deleterious mutations in the disorder and the comorbidity associated with
these heritable mutations.
Several studies demonstrating that central line–associated bloodstream infections (CLABSIs) are preventable prompted a national initiative to reduce the incidence of these infections.
We conducted a collaborative cohort study to evaluate the impact of the national “On the CUSP: Stop BSI” program on CLABSI rates among participating adult intensive care units (ICUs). The program goal was to achieve a unit-level mean CLABSI rate of less than 1 case per 1,000 catheter-days using standardized definitions from the National Healthcare Safety Network. Multilevel Poisson regression modeling compared infection rates before, during, and up to 18 months after the intervention was implemented.
A total of 1,071 ICUs from 44 states, the District of Columbia, and Puerto Rico, reporting 27,153 ICU-months and 4,454,324 catheter-days of data, were included in the analysis. The overall mean CLABSI rate significantly decreased from 1.96 cases per 1,000 catheter-days at baseline to 1.15 at 16–18 months after implementation. CLABSI rates decreased during all observation periods compared with baseline, with adjusted incidence rate ratios steadily decreasing to 0.57 (95% confidence intervals, 0.50–0.65) at 16–18 months after implementation.
Coincident with the implementation of the national “On the CUSP: Stop BSI” program was a significant and sustained decrease in CLABSIs among a large and diverse cohort of ICUs, demonstrating an overall 43% decrease and suggesting the majority of ICUs in the United States can achieve additional reductions in CLABSI rates.
We explore a model of heat transport between two heat reservoirs mediated by a quantum particle. The reservoirs are modeled as ensembles of harmonic modes linearly coupled to the mediator. The steady state heat current, as well as the thermal conductance are obtained for arbitrary coupling strength and will be analyzed for the cases of weak and strong coupling regimes. It is shown that the violation of the virial theorem – the imbalance between the average potential and kinetic energy of the mediator – can be considered as a measure of the coupling strength that takes into account all the relevant factors. The dependence of the thermal conductance on the coupling strength is non-monotonic and displays a maximum. Temperature dependence of the heat conductance may reach a plateau at intermediate temperatures, similar to the classical plateau at high temperatures. We will discuss the origin of Fourier’s law in a chain of macroscopically large, but finite subsystems coupled by the quantum mediators. We will also address the origin of the anomalously large heat current between the scanning tunneling microscope tip and the substrate in deep vacuum which was found in recent experiments.
The Parkes pulsar data archive currently provides access to 144044 data files obtained from observations carried out at the Parkes observatory since the year 1991. Around 105 files are from surveys of the sky, the remainder are observations of 775 individual pulsars and their corresponding calibration signals. Survey observations are included from the Parkes 70 cm and the Swinburne Intermediate Latitude surveys. Individual pulsar observations are included from young pulsar timing projects, the Parkes Pulsar Timing Array and from the PULSE@Parkes outreach program. The data files and access methods are compatible with Virtual Observatory protocols. This paper describes the data currently stored in the archive and presents ways in which these data can be searched and downloaded.
Multi-slice computed tomography (MSCT) has proven in
several studies to have a high diagnostic accuracy for the detection
or exclusion of coronary artery disease. A major concern with coronary
MSCT, however, is the associated radiation exposure of patients.
Recent studies suggest that use of a 64-slice scanner is associated
with a non-negligible lifetime attributable risk of cancer. Several
strategies can be used to reduce patient exposure in coronary MSCT.
The purpose of this multicenter study was to investigate the effects
of the adjustment of tube voltage and current on radiation dose
and image interpretability. MSCT with retrospective ECG gating was performed
in 315 patients. The dose-length product (DLP) in the patients enrolled
with the dose reduction protocol resulted in a 36% overall reduction
in the mean radiation dose (911 ± 289 mGy.cm) compared with the
standard protocol (1427 ± 226 mGy.cm, p < 0.001).
Nevertheless, image interpretability was maintained. This study
on coronary MSCT demonstrates that the radiation dose can be significantly reduced
by parameter optimization, with maintained image interpretability.
We have studied the influence of ultra-thin interfacial Fe layers on the structural and magnetoresistance properties of CO/Cu Multilayers. Our results show that the giant magnetoresistance arises from spin dependent scattering at the CO/Cu interfaces and in the bulk of Co, the interfacial contribution being predominant. We also demonstrate that the close-packed crystallographic structure of Co and Cu is very sensitive to the insertion of interfacial bec Fe layers: for small thicknesses, Co as well as Cu adopt a metastable bec structure.