273 research outputs found

    Antibunched photons emitted by a dc-biased Josephson junction

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    We show experimentally that a dc biased Josephson junction in series with a high-enough-impedance microwave resonator emits antibunched photons. Our resonator is made of a simple microfabricated spiral coil that resonates at 4.4 GHz and reaches a 1.97kΩ characteristic impedance. The second order correlation function of the power leaking out of the resonator drops down to 0.3 at zero delay, which demonstrates the antibunching of the photons emitted by the circuit at a rate of 6×10^7 photons per second. Results are found in quantitative agreement with our theoretical predictions. This simple scheme could offer an efficient and bright single-photon source in the microwave domain

    Signal height in silicon pixel detectors irradiated with pions and protons

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    Pixel detectors are used in the innermost part of multi purpose experiments at the Large Hadron Collider (LHC) and are therefore exposed to the highest fluences of ionising radiation, which in this part of the detectors consists mainly of charged pions. The radiation hardness of the detectors has thoroughly been tested up to the fluences expected at the LHC. In case of an LHC upgrade the fluence will be much higher and it is not yet clear up to which radii the present pixel technology can be used. In order to establish such a limit, pixel sensors of the size of one CMS pixel readout chip (PSI46V2.1) have been bump bonded and irradiated with positive pions up to 6E14 Neq/cm^2 at PSI and with protons up to 5E15 Neq/cm^2. The sensors were taken from production wafers of the CMS barrel pixel detector. They use n-type DOFZ material with a resistance of about 3.7kOhm cm and an n-side read out. As the performance of silicon sensors is limited by trapping, the response to a Sr-90 source was investigated. The highly energetic beta-particles represent a good approximation to minimum ionising particles. The bias dependence of the signal for a wide range of fluences will be presented.Comment: Contribution to the 7th International Conference on Radiation Effects on Semiconductor Materials, Detectors and Devices October 15-17, 2008 Firenze, Ital

    Generating Two Continuous Entangled Microwave Beams Using a dc-Biased Josephson Junction

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    We show experimentally that a dc-biased Josephson junction in series with two microwave resonators emits entangled beams of microwaves leaking out of the resonators. In the absence of a stationary phase reference for characterizing the entanglement of the outgoing beams, we measure second-order coherence functions to prove the entanglement. The experimental results are found in quantitative agreement with theory, proving that the low-frequency noise of the dc bias is the main limitation for the coherence time of the entangled beams. This agreement allows us to evaluate the entropy of entanglement of the resonators, estimate the entanglement flux at their output, and to identify the improvements that could bring this device closer to a useful bright source of entangled microwaves for quantum-technological applications

    Implementation of a Rapid Assessment Unit (Intake Team): Impact on Emergency Department Length of Stay

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    Implementation of a Rapid Assessment Unit (Intake Team): Impact on Emergency Department Length of Stay Richard S. MacKenzie, MD, David B. Burmeister, DO, Jennifer A. Brown, RN, Melissa Teitsworth, RN, BSN, Christopher J. Kita, MEd, Megan J. Dambach, DO, Shaheen Shamji, DO, Anita Kurt, PhD, RN , Susan Friend, Marna Greenberg, DO, MPH Acknowledge: Clare M. Lenhart, PhD, MPH Objective: Emergency Department (ED) crowding is an on-going formidable issue for many EDs. A Rapid Assessment Unit (RAU) is a potential solution. This process involves the use of a team approach to convert the current “series” type evaluation to a more “parallel” evaluation and treatment of patients. The RAU concept of evaluating and treating ED patients radically changes the current methods utilized in today’s standard emergency care area. The RAU concept offers a process in which the patient walks into the ED and is seen in a unit by an intake team composed of a nurse, registrar, and provider (physician assistant, nurse practitioner, or physician) that provides evaluation and emergent treatment. This removes the redundancy of a patient giving the same information several times before they are treated. Simultaneously, the team decides whether the patient would be better served by remaining seated or requires a recumbent position. This is referred to as allowing “vertical flow” versus the default “horizontal flow” where all patients recline on a stretcher whether they need it or not. Certainly, having construction that specifically supports these processes is an innovation as well (having an area where patients can be seated and remain “vertical”). The team structure itself is unique. The nurses and providers are not assigned geographically by room but rather are defined by their function. We set out to determine if the addition of the RAU process would decreases the LOS of the discharged ambulatory arrival patient. Methods: After IRB approval, this retrospective, pre- and post intervention, observational comparison study was conducted from August 2011-March 2012 at a suburban teaching hospital in central Pennsylvania with an annual ED census of approximately 54,000. The inclusion criteria were all ambulatory discharged patients. The exclusion criteria were all patients that arrived by ambulance and admitted patients. Data points captured included: time of arrival in triage , time in triage to ED entry, time of ED entry until seen by a provider, time from ED entry to discharge, total length of stay (LOS). The data were uploaded to Horizon Business Insight™ (HBI), a cumulative data manager and exported to an Microsoft excel file for analysis. Mann-Whitney U tests were used to demonstrate differences in Median LOS. All statistical tests were 2-sided; probability values \u3c0.05 were considered significant. Results: 11, 994 pre and 10814 post-RAU patients were included in analysis. Median LOS was shorter during the post-RAU period in each subcategory of LOS with the exception of the interval from being seen in the ER to discharge which is a result of provider seeing the patient earlier in the ED encounter. Results, Table 1. Conclusions: The RAU process decreases the LOS of the discharged ambulatory arrival patient and deserves further exploration as an innovative model in the ED that improves flow

    Spatial heterogeneity of habitat suitability for Rift Valley fever occurrence in Tanzania: an ecological niche modelling approach

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    Despite the long history of Rift Valley fever (RVF) in Tanzania, extent of its suitable habitat in the country remains unclear. In this study we investigated potential effects of temperature, precipitation, elevation, soil type, livestock density, rainfall pattern, proximity to wild animals, protected areas and forest on the habitat suitability for RVF occurrence in Tanzania. Presence-only records of 193 RVF outbreak locations from 1930 to 2007 together with potential predictor variables were used to model and map the suitable habitats for RVF occurrence using ecological niche modelling. Ground-truthing of the model outputs was conducted by comparing the levels of RVF virus specific antibodies in cattle, sheep and goats sampled from locations in Tanzania that presented different predicted habitat suitability values. Habitat suitability values for RVF occurrence were higher in the northern and central-eastern regions of Tanzania than the rest of the regions in the country. Soil type and precipitation of the wettest quarter contributed equally to habitat suitability (32.4% each), followed by livestock density (25.9%) and rainfall pattern (9.3%). Ground-truthing of model outputs revealed that the odds of an animal being seropositive for RVFV when sampled from areas predicted to be most suitable for RVF occurrence were twice the odds of an animal sampled from areas least suitable for RVF occurrence (95% CI: 1.43, 2.76, p < 0.001). The regions in the northern and central-eastern Tanzania were more suitable for RVF occurrence than the rest of the regions in the country. The modelled suitable habitat is characterised by impermeable soils, moderate precipitation in the wettest quarter, high livestock density and a bimodal rainfall pattern. The findings of this study should provide guidance for the design of appropriate RVF surveillance, prevention and control strategies which target areas with these characteristics

    Performance of the CMS Cathode Strip Chambers with Cosmic Rays

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    The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns

    Characterization of primary human hepatocytes, HepG2 cells, and HepaRG cells at the mRNA level and CYP activity in response to inducers and their predictivity for the detection of human hepatotoxins

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    In the pharmaceutical industry, improving the early detection of drug-induced hepatotoxicity is essential as it is one of the most important reasons for attrition of candidate drugs during the later stages of drug development. The first objective of this study was to better characterize different cellular models (i.e., HepG2, HepaRG cells, and fresh primary human hepatocytes) at the gene expression level and analyze their metabolic cytochrome P450 capabilities. The cellular models were exposed to three different CYP450 inducers; beta-naphthoflavone (BNF), phenobarbital (PB), and rifampicin (RIF). HepG2 cells responded very weakly to the different inducers at the gene expression level, and this translated generally into low CYP450 activities in the induced cells compared with the control cells. On the contrary, HepaRG cells and the three human donors were inducible after exposure to BNF, PB, and RIF according to gene expression responses and CYP450 activities. Consequently, HepaRG cells could be used in screening as a substitute and/or in complement to primary hepatocytes for CYP induction studies. The second objective was to investigate the predictivity of the different cellular models to detect hepatotoxins (16 hepatotoxic and 5 nonhepatotoxic compounds). Specificity was 100% with the different cellular models tested. Cryopreserved human hepatocytes gave the highest sensitivity, ranging from 31% to 44% (depending on the donor), followed by lower sensitivity (13%) for HepaRG and HepG2 cells (6.3%). Overall, none of the models under study gave desirable sensitivities (80–100%). Consequently, a high metabolic capacity and CYP inducibility in cell lines does not necessarily correlate with a high sensitivity for the detection of hepatotoxic drugs. Further investigations are necessary to compare different cellular models and determine those that are best suited for the detection of hepatotoxic compounds

    Performance and Operation of the CMS Electromagnetic Calorimeter

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    The operation and general performance of the CMS electromagnetic calorimeter using cosmic-ray muons are described. These muons were recorded after the closure of the CMS detector in late 2008. The calorimeter is made of lead tungstate crystals and the overall status of the 75848 channels corresponding to the barrel and endcap detectors is reported. The stability of crucial operational parameters, such as high voltage, temperature and electronic noise, is summarised and the performance of the light monitoring system is presented
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