279 research outputs found

    Different twins in the millisecond pulsar recycling scenario: optical polarimetry of PSR J1023+0038 and XSS J12270-4859

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    We present the first optical polarimetric study of the two transitional pulsars PSR J1023+0038 and XSS J12270-4859. This work is focused on the search for intrinsical linear polarisation (LP) in the optical emission from the two systems. We carried out multiband optical and NIR photo-polarimetry of the two systems using the ESO NTT at La Silla (Chile), equipped with the EFOSC2 and the SOFI instruments. XSS J12270-4859 was observed during its radio-pulsar state; we did not detect LP in all bands, with 3 sigma upper limits of, e.g., 1.4% in the R-band. We built the NIR-optical averaged spectral energy distribution (SED) of the system, that could be well described by an irradiated black body with radius R=0.33±0.03RR_{*} = 0.33\pm0.03\,R_{\odot} and albedo η=0.32±0.05\eta=0.32\pm0.05, without the need of further components (thus excluding the visible presence of an extended accretion disc and/or of relativistic jets). The case was different for PSR J1023+0038, that was in its accretion phase during our campaign. We measured a LP of 1.09±0.27%1.09\pm0.27\% and 0.90±0.17%0.90\pm 0.17\% in the V and R bands, respectively. The phase-resolved polarimetric curve of the source in the R-band reveals a hint of a sinusoidal modulation at the source 4.75 hr orbital period, peaked at the same orbital phase as the light curve. The measured LP of PSR J1023+0038 could in principle be interpreted as scattering with free electrons (that can be found in the accretion disc of the system or even in the hot corona that surrounds the disc itself) or to synchrotron emission from a relativistic particles jet or outflow. However, the NIR-optical SED of the system built starting from our dataset did not suggest the presence of a jet. We conclude that the optical LP observed for PSR J1023+0038 is possibly due to Thomson scattering with electrons in the disc, as also suggested from the possible modulation of the R-band LP at the system orbital period.Comment: 10 pages, 8 figures, 4 tables. Accepted for publication in Sec. 7. Stellar structure and evolution of Astronomy and Astrophysic

    Detailed X-ray spectroscopy of the magnetar 1E 2259+586

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    Magnetic field geometry is expected to play a fundamental role in magnetar activity. The discovery of a phase-variable absorption feature in the X-ray spectrum of SGR 0418+5729, interpreted as cyclotron resonant scattering, suggests the presence of very strong non-dipolar components in the magnetic fields of magnetars. We performed a deep XMM-Newton observation of pulsar 1E 2259+586, to search for spectral features due to intense local magnetic fields. In the phase-averaged X-ray spectrum, we found evidence for a broad absorption feature at very low energy (0.7 keV). If the feature is intrinsic to the source, it might be due to resonant scattering/absorption by protons close to star surface. The line energy implies a magnetic field of ~ 10^14 G, roughly similar to the spin-down measure, ~ 6x10^13 G. Examination of the X-ray phase-energy diagram shows evidence for a further absorption feature, the energy of which strongly depends on the rotational phase (E >~ 1 keV ). Unlike similar features detected in other magnetar sources, notably SGR 0418+5729, it is too shallow and limited to a small phase interval to be modeled with a narrow phase-variable cyclotron absorption line. A detailed phase-resolved spectral analysis reveals significant phase-dependent variability in the continuum, especially above 2 keV. We conclude that all the variability with phase in 1E 2259+586 can be attributed to changes in the continuum properties which appear consistent with the predictions of the Resonant Compton Scattering model

    Undernutrition is associated with increased financial losses in hospitals.

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    Undernutrition is associated with increased hospital costs. Whether these increased costs are totally compensated by third payer systems has not been assessed. We aimed to assess the differences between actual and reimbursed hospital costs according to presence/absence of nutritional risk, defined by a Nutritional risk screening-2002 (NRS-2002) score ≥3. Retrospective study. Administrative data for years 2013 and 2014 of the department of internal medicine of the Lausanne university hospital. The data included total and specific costs (i.e. clinical biology, treatments, pathology). Reimbursed costs were based on the Swiss Diagnosis Related Group (DRG) system. 2200 admissions with NRS-2002 data were included (mean age 76 years, 53.9% women), 1398 (63.6%) of which were considered nutritionally 'at-risk'. After multivariate adjustment, patients nutritionally 'at-risk' had higher costs (multivariate-adjusted difference ± standard error: 34,206 ± 1246 vs. 22,214 ± 1666 CHF, p < 0.001) and higher reimbursements (26,376 ± 1105 vs. 17,783 ± 1477 CHF, p < 0.001). Still, the latter failed to cover the costs, leading to a deficit between costs and reimbursements of 7831 ± 660 CHF in patients 'at-risk' vs. 4431 ± 881 in patients 'not at-risk' (p < 0.003). Being nutritionally 'at-risk' also led to a lower likelihood of complete coverage of costs: multivariate-adjusted odds ratio and 95% confidence interval 0.77 (0.62-0.97). Patients 'at-risk' had lower percentage of total costs in medical interventions, food, imaging and "other", but the absolute differences were less than 2%. Hospital costs of patients nutritionally 'at-risk' are less well reimbursed than of patients 'not at-risk'. Better reporting of undernutrition in medical records and better reimbursement of undernourished patients is needed

    Postoperative Albumin Drop Is a Marker for Surgical Stress and a Predictor for Clinical Outcome: A Pilot Study.

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    Background. Surgical stress during major surgery may be related to adverse clinical outcomes and early quantification of stress response would be useful to allow prompt interventions. The aim of this study was to evaluate the acute phase protein albumin in the context of the postoperative stress response. Methods. This prospective pilot study included 70 patients undergoing frequent abdominal procedures of different magnitude. Albumin (Alb) and C-reactive protein (CRP) levels were measured once daily starting the day before surgery until postoperative day (POD) 5. Maximal Alb decrease (Alb Δ min) was correlated with clinical parameters of surgical stress, postoperative complications, and length of stay. Results. Albumin values dropped immediately after surgery by about 10 g/L (42.2 ± 4.5 g/L preoperatively versus 33.8 ± 5.3 g/L at day 1, P < 0.001). Alb Δ min was correlated with operation length (Pearson ρ = 0.470, P < 0.001), estimated blood loss (ρ = 0.605, P < 0.001), and maximal CRP values (ρ = 0.391, P = 0.002). Alb Δ min levels were significantly higher in patients having complications (10.0 ± 5.4 versus 6.1 ± 5.2, P = 0.005) and a longer hospital stay (ρ = 0.285, P < 0.020). Conclusion. Early postoperative albumin drop appeared to reflect the magnitude of surgical trauma and was correlated with adverse clinical outcomes. Its promising role as early marker for stress response deserves further prospective evaluation

    Efficiency of the lausanne clinical pathway for proximal femoral fractures.

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    Purpose/Introduction: The number of hip fractures is rising, due to increases in life expectancy. In such cases, patients are at risk from post-operative complications and subsequently the average length of hospitalization may be extended. In 2011, we established a clinical pathway (CP), a specific model of care for patient-care management, to improve the clinical and economic outcomes of proximal femoral fracture management in elderly patients. The goal was to evaluate the CP using clinical, process, and financial indicators. METHODS: We included all surgical patients aged 65 and over, admitted to the emergency department with a fracture of the proximal femur following a fall. Assessment parameters included three performance indicators: clinical, process, and financial. The clinical indicators were the presence or absence of acute delirium on the third post-operative day, diagnosis of nosocomial pneumonia, and the number of patients fulfilling at least 75% of their nutritional requirements at the end of the hospitalization period. The process indicator was the time interval between arrival at the emergency department and surgery. The financial indicator was based on the number of days spent in hospital. RESULTS: From 2011 to 2013, 669 patients were included in the CP. We observed that the average length of stay in hospital decreased as soon as the CP was implemented and stabilized afterwards. The goal of 90% of patients undergoing surgery within 48 h of arrival in the emergency department was surpassed in 2013 (93.1%). Furthermore, we observed an improvement in the clinical indicators. CONCLUSION: The application of a CP allowed an improvement in the qualitative and quantitative efficiency of proximal femoral fracture management in elderly patients, in terms of clinical, process, and financial factors

    Simultaneous Multi-band Radio & X-ray Observations of the Galactic Center Magnetar SGR 1745-2900

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    We report on multi-frequency, wideband radio observations of the Galactic Center magnetar (SGR 1745-2900) with the Green Bank Telescope for \sim100 days immediately following its initial X-ray outburst in April 2013. We made multiple simultaneous observations at 1.5, 2.0, and 8.9 GHz, allowing us to examine the magnetar's flux evolution, radio spectrum, and interstellar medium parameters (such as the dispersion measure (DM), the scattering timescale and its index). During two epochs, we have simultaneous observations from the Chandra X-ray Observatory, which permitted the absolute alignment of the radio and X-ray profiles. As with the two other radio magnetars with published alignments, the radio profile lies within the broad peak of the X-ray profile, preceding the X-ray profile maximum by \sim0.2 rotations. We also find that the radio spectral index γ\gamma is significantly negative between \sim2 and 9 GHz; during the final \sim30 days of our observations γ1.4\gamma \sim -1.4, which is typical of canonical pulsars. The radio flux has not decreased during this outburst, whereas the long-term trends in the other radio magnetars show concomitant fading of the radio and X-ray fluxes. Finally, our wideband measurements of the DMs taken in adjacent frequency bands in tandem are stochastically inconsistent with one another. Based on recent theoretical predictions, we consider the possibility that the dispersion measure is frequency-dependent. Despite having several properties in common with the other radio magnetars, such as LX,qui/Lrot1L_{\textrm{X,qui}}/L_{\textrm{rot}} \lesssim 1, an increase in the radio flux during the X-ray flux decay has not been observed thus far in other systems.Comment: 15 pages, 9 figures, 3 tables; accepted to Ap
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