754 research outputs found

    A 1200-micron MAMBO survey of ELAISN2 and the Lockman Hole - I. Maps, sources and number counts

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    The definitive version is available at www.blackwell-synergy.com '.--Copyright Blackwell Publishing. DOI : 10.1111/j.1365-2966.2004.08235.xWe present a deep, new 1200μm survey of the ELAISN2 and Lockman Hole fields using the Max Planck Millimeter Bolometer array (MAMBO). The areas surveyed are 160 arcmin2 in ELAISN2 and 197 arcmin2 in the Lockman Hole, covering the entire SCUBA ‘8mJy Survey’. In total, 27 (44) sources have been detected at a significance 4.0 ( 3.5 ). The primary goals of the survey were to investigate the reliability of (sub)millimetre galaxy (SMG) samples, to analyse SMGs using flux ratios sensitive to redshift at z > 3, and to search for ‘SCUBA drop-outs’, i.e. galaxies at z >> 3. We present the 1200μm number counts and find evidence of a fall at bright flux levels. Employing parametric models for the evolution of the local 60μm IRAS luminosity function (LF), we are able to account simultaneously for the 1200 and 850μm counts, suggesting that the MAMBO and SCUBA sources trace the same underlying population of high-redshift, dust-enshrouded galaxies. From a nearest-neighbour clustering analysis we find tentative evidence that themost significantMAMBO sources come in pairs, typically separated by 23′′. Our MAMBO observations unambiguously confirm around half of the SCUBA sources. In a robust sub-sample of 13 SMGs detected by both MAMBO and SCUBA at a significance 3.5 , only one has no radio counterpart. Furthermore, the distribution of 850/1200μmflux density ratios for this sub-sample is consistent with the spectroscopic redshift distribution of radio-detected SMGs (Chapman et al. 2003). Finally, we have searched for evidence of a high-redshift tail of SMGs amongst the 18 MAMBO sources which are not detected by SCUBA. While we cannot rule out that some of them are SCUBA drop-outs at z >> 3, their overall 850-to-1200μm flux distribution is statistically indistinguishable from that of the 13 SMGS which were robustly identified by both MAMBO and SCUBA.Peer reviewe

    Quantum well and dot self-aligned stripe lasers utilizing an InGaP optoelectronic confinement layer

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    We demonstrate and study a novel process for fabrication of GaAs-based self-aligned lasers based upon a single over-growth. A lattice-matched n-doped InGaP layer is utilized for both electrical and optical confinements. Single-lateral-mode emission is demonstrated initially from an In0.17Ga0.83 As double quantum well laser emitting similar to 980 nm. We then apply the fabrication technique to a quantum dot laser emitting similar to 1300 nm. Furthermore, we analyze the breakdown mechanism in our devices and discuss the limitations of index guiding in our structures

    First Measurements with NeXtRAD, a Polarimetric X/L Band Radar Network

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    NeXtRAD is a fully polarimetric, X/L Band radar network. It is a development of the older NetRAD system and builds on the experience gained with extensive deployments of NetRAD for sea clutter and target measurements. In this paper we will report on the first measurements with NeXtRAD, looking primarily at sea clutter and some targets, as well as early attempts at calibration using corner reflectors, and an assessment of the polarimetric response of the system. We also highlight innovations allowing for efficient data manipulation post measurement campaigns, as well as the plans for the coming years with this system

    VIP enhances TRH-stimulated prolactin secretion of pituitary tumours Studies with 31P NMR

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    AbstractIntravenous thyrotrophin releasing hormone (TRH) caused a 6.5-fold increase in plasma prolactin (PRL) in rats carrying implanted pituitary tumours. Vasoactive intestinal polypeptide (VIP) had no effect, but TRH given after VIP raised TRH stimulated secretion 13-fold above basal. 31P NMR spectroscopy showed that VIP caused a decrease in high energy metabolites (depleted phosphocreatine, elevated inorganic phosphate and lowered intracellular pH). TRH alone caused a similar but smaller effect; given after VIP, it caused no detectable depletion. We suggest that the changes in high energy metabolite cencentrations reflect increased cellular energy consumption consistent with a priming process (stage 1) in PRL secretion, followed by hormone release (stage 2). VIP induces stage 1 whereas RTH induced both stages

    Pre-existing virus-specific CD8+ T-cells provide protection against pneumovirus-induced disease in mice

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    Pneumoviruses such as pneumonia virus of mice (PVM), bovine respiratory syncytial virus (bRSV) or human (h)RSV are closely related pneumoviruses that cause severe respiratory disease in their respective hosts. It is well-known that T-cell responses are essential in pneumovirus clearance, but pneumovirus-specific T-cell responses also are important mediators of severe immunopathology. In this study we determined whether memory- or pre-existing, transferred virus-specific CD8 + T-cells provide protection against PVM-induced disease. We show that during infection with a sublethal dose of PVM, both natural killer (NK) cells and CD8 + T-cells expand relatively late. Induction of CD8 + T-cell memory against a single CD8 + T-cell epitope, by dendritic cell (DC)-peptide immunization, leads to partial protection against PVM challenge and prevents Th2 differentiation of PVM-induced CD4 T-cells. In addition, adoptively transferred PVM-specific CD8 + T-cells, covering the entire PVM-specific CD8 + T-cell repertoire, provide partial protection from PVM-induced disease. From these data we infer that antigen-specific memory CD8 + T-cells offer significant protection to PVM-induced disease. Thus, CD8 + T-cells, despite being a major cause of PVM-associated pathology during primary infection, may offer promising targets of a protective pneumovirus vaccine

    Effects of trauma-related cues on pain processing in posttraumatic stress disorder: an fMRI investigation

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    Background: Imaging studies of pain processing in primary psychiatric disorders are just emerging. This study explored the neural correlates of stress-induced analgesia in individuals with posttraumatic stress disorder (PTSD). It combined functional magnetic resonance imaging (fMRI) and the traumatic script-driven imagery symptom provocation paradigm to examine the effects of trauma-related cues on pain perception in individuals with PTSD. Methods: The study included 17 patients with PTSD and 26 healthy, trauma-exposed controls. Participants received warm (nonpainful) or hot (painful) thermal stimuli after listening to a neutral or a traumatic script while they were undergoing an fMRI scan at a 4.0 T field strength. Results: Between-group analyses revealed that after exposure to the traumatic scripts, the blood oxygen level–dependent (BOLD) signal during pain perception was greater in the PTSD group than the control group in the head of the caudate. In the PTSD group, strong positive correlations resulted between BOLD signal and symptom severity in a number of brain regions previously implicated in stress-induced analgesia, such as the thalamus and the head of the caudate nucleus. Trait dissociation as measured by the Dissociative Experiences Scale correlated negatively with the right amygdala and the left putamen. Limitations: This study included heterogeneous traumatic experiences, a different proportion of military trauma in the PTSD versus the control group and medicated patients with PTSD. Conclusion: These data indicate that in patients with PTSD trauma recall will lead in a state-dependent manner to greater activation in brain regions implicated in stress-induced analgesia. Correlational analyses lend support to cortical hyperinhibition of the amygdala as a function of dissociation

    Herschel-ATLAS/GAMA: A difference between star formation rates in strong-line and weak-line radio galaxies

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    We have constructed a sample of radio-loud objects with optical spectroscopy from the Galaxy and Mass Assembly (GAMA) project over the Herschel Astrophysical Terahertz Large Area Survey (Herschel-ATLAS) Phase 1 fields. Classifying the radio sources in terms of their optical spectra, we find that strong-emission-line sources ('high-excitation radio galaxies') have, on average, a factor of ~4 higher 250-μm Herschel luminosity than weak-line ('lowexcitation') radio galaxies and are also more luminous than magnitude-matched radio-quiet galaxies at the same redshift. Using all five H-ATLAS bands, we show that this difference in luminosity between the emission-line classes arises mostly from a difference in the average dust temperature; strong-emission-line sources tend to have comparable dust masses to, but higher dust temperatures than, radio galaxies with weak emission lines. We interpret this as showing that radio galaxies with strong nuclear emission lines are much more likely to be associated with star formation in their host galaxy, although there is certainly not a one-to-one relationship between star formation and strong-line active galactic nuclei (AGN) activity. The strong-line sources are estimated to have star formation rates at least a factor of 3-4 higher than those in the weak-line objects. Our conclusion is consistent with earlier work, generally carried out using much smaller samples, and reinforces the general picture of high-excitation radio galaxies as being located in lower-mass, less evolved host galaxies than their low-excitation counterparts.Peer reviewe

    Effectiveness of a home-based rehabilitation program after total hip arthroplasty driven by a tablet app and remote coaching:nonrandomized controlled trial combining a single-arm intervention cohort with historical controls

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    Background: Recent technological developments such as wearable sensors and tablets with a mobile internet connection hold promise for providing electronic health home-based programs with remote coaching for patients following total hip arthroplasty. It can be hypothesized that such a home-based rehabilitation program can offer an effective alternative to usual care. Objective: The aim of this study was to determine the effectiveness of a home-based rehabilitation program driven by a tablet app and remote coaching for patients following total hip arthroplasty. Methods: Existing data of two studies were combined, in which patients of a single-arm intervention study were matched with historical controls of an observational study. Patients aged 18-65 years who had undergone total hip arthroplasty as a treatment for primary or secondary osteoarthritis were included. The intervention consisted of a 12-week home-based rehabilitation program with video instructions on a tablet and remote coaching (intervention group). Patients were asked to do strengthening and walking exercises at least 5 days a week. Data of the intervention group were compared with those of patients who received usual care (control group). Effectiveness was measured at four moments (preoperatively, and 4 weeks, 12 weeks, and 6 months postoperatively) by means of functional tests (Timed Up & Go test and the Five Times Sit-to Stand Test) and self-reported questionnaires (Hip disability and Osteoarthritis Outcome Score [HOOS] and Short Form 36 [SF-36]). Each patient of the intervention group was matched with two patients of the control group. Patient characteristics were summarized with descriptive statistics. The 1:2 matching situation was analyzed with a conditional logistic regression. Effect sizes were calculated by Cohen d. Results: Overall, 15 patients of the intervention group were included in this study, and 15 and 12 subjects from the control group were matched to the intervention group, respectively. The intervention group performed functional tests significantly faster at 12 weeks and 6 months postoperatively. The intervention group also scored significantly higher on the subscales “function in sport and recreational activities” and “hip-related quality of life” of HOOS, and on the subscale “physical role limitations” of SF-36 at 12 weeks and 6 months postoperatively. Large effect sizes were found on functional tests at 12 weeks and at 6 months (Cohen d=0.5-1.2), endorsed by effect sizes on the self-reported outcomes. Conclusions: Our results clearly demonstrate larger effects in the intervention group compared to the historical controls. These results imply that a home-based rehabilitation program delivered by means of internet technology after total hip arthroplasty can be more effective than usual care

    Simulations of the Static Friction Due to Adsorbed Molecules

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    The static friction between crystalline surfaces separated by a molecularly thin layer of adsorbed molecules is calculated using molecular dynamics simulations. These molecules naturally lead to a finite static friction that is consistent with macroscopic friction laws. Crystalline alignment, sliding direction, and the number of adsorbed molecules are not controlled in most experiments and are shown to have little effect on the friction. Temperature, molecular geometry and interaction potentials can have larger effects on friction. The observed trends in friction can be understood in terms of a simple hard sphere model.Comment: 13 pages, 13 figure
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