We present a comprehensive data description for K sub(s)-band measurements of Sgr A*. We characterize the statistical properties of the variability of Sgr A* in the near-infrared, which we find to be ...consistent with a single-state process forming a power-law distribution of the flux density. We discover a linear rms-flux relation for the flux density range up to 12 mJy on a timescale of 24 minutes. This and the power-law flux density distribution implies a phenomenological, formally nonlinear statistical variability model with which we can simulate the observed variability and extrapolate its behavior to higher flux levels and longer timescales. We present reasons why data with our cadence cannot be used to decide on the question whether the power spectral density of the underlying random process shows more structure at timescales between 25 minutes and 100 minutes compared to what is expected from a red-noise random process.
The Refeeding Syndrome (RFS) is a serious complication in patients receiving nutrition support after a period of severe malnutrition. We frequently recognize and diagnose the RFS due to increased ...awareness. Thus, we observe that many physicians do not know the RFS and that it is rarely diagnosed. The aim of the study was to determine whether physicians in Germany know the RFS.
A questionnaire with a case vignette about an older person who developed the RFS after initiation of nutritional therapy was submitted to German physicians and fifth year medical students, who were participants of educational lectures.
Of the 281 participants who answered the respective question, 40 participants (14%) correctly diagnosed the RFS of the case vignette and 21 participants (8%) gave nearly correct answers. Indeed, the majority of the participants did not diagnose the RFS.
Although the RFS may lead to fatal complications, it is unknown to the majority of the queried physicians. Therefore, there is a call to implement the RFS in respective curricula and increase systematic education on this topic.
For the diagnosis, prevention and therapy of malnutrition, it is important to estimate the energy and fluid requirements of an individual patient. To our knowledge, it is unknown how accurately ...medical doctors can estimate the energy and fluid requirements of patients in a clinical routine situation. Hence, we conducted the following survey. A written face-to-face survey about the energy and fluid requirements of and tube feeding and fluid recommendations for a typical patient was performed with 179 medical doctors. An estimation error of >15% was defined as relevant. The results revealed substantial variations in estimating the energy and fluid needs of the patient. A total of 25% of the participants underestimated the energy requirements, and 47% of the participants underestimated the fluid requirements. In addition, 68% of the participants recommended a daily dose of tube feeding that was <85% of the reference value. A substantial proportion of medical doctors show a lack of knowledge concerning energy and fluid requirements, which demonstrates a need for better medical education with regard to nutrition.
Context. We report on the results of calibrating and simulating the instrumental polarization properties of the ESO VLT adaptive optics camera system NAOS/CONICA (NACO) in the Ks-band. Aims. Our goal ...is to understand the influence of systematic calibration effects on the time-resolved polarimetric observations of the infrared counterpart of the Galactic center super-massive black hole at the position of Sagittarius A* (Sgr A*). Methods. We use the Stokes/Mueller formalism for metallic reflections to describe the instrumental polarization. The model is compared to standard-star observations and time-resolved observations of bright sources in the Galactic center. The differences between calibration methods are simulated and tested for three polarimetric Ks-band light curves of Sgr A*. Results. We find the instrumental polarization to be highly dependent on the pointing position of the telescope and about 4% at maximum. Given the statistical uncertainties in the data acquisition, the systematic effects of the employed calibration method are negligible at high-time resolution, as it is necessary and achieved for in the case of Sgr A*. We report a polarization angle offset of 13.2° due to a position angle offset of the λ/2-wave plate with respect to the header value that affects the calibration of NACO data taken before autumn 2009. Conclusions. With the new model of the instrumental polarization of NACO it is possible to measure the polarization with an accuracy of 1% in polarization degree. The uncertainty of the polarization angle is ≤ 5° for polarization degrees ≥ 4%. For highly sampled polarimetric time series we find that the improved understanding of the polarization properties gives results that are fully consistent with the previously used method to derive the polarization. The small difference between the derived and the previously employed polarization calibration is well within the statistical uncertainties of the measurements, and for Sgr A* they do not affect the results from our relativistic modeling of the accretion process.
Many galaxies are thought to have supermassive black holes at their centres-more than a million times the mass of the Sun. Measurements of stellar velocities and the discovery of variable X-ray ...emission have provided strong evidence in favour of such a black hole at the centre of the Milky Way, but have hitherto been unable to rule out conclusively the presence of alternative concentrations of mass. Here we report ten years of high-resolution astrometric imaging that allows us to trace two-thirds of the orbit of the star currently closest to the compact radio source (and massive black-hole candidate) Sagittarius A*. The observations, which include both pericentre and apocentre passages, show that the star is on a bound, highly elliptical keplerian orbit around Sgr A*, with an orbital period of 15.2 years and a pericentre distance of only 17 light hours. The orbit with the best fit to the observations requires a central point mass of (3.7 ± 1.5) × 106 solar masses (M ). The data no longer allow for a central mass composed of a dense cluster of dark stellar objects or a ball of massive, degenerate fermions.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Due to its proximity, youth, and solar-like characteristics with a spectral type of K2V, epsilon Eri is one of the most extensively studied systems in an extrasolar planet context. Based on radial ...velocity, astrometry, and studies of the structure of its circumstellar debris disk, at least two planetary companion candidates to epsilon Eri have been inferred in the literature (\epsilon Eri b, epsilon Eri c). Some of these methods also hint at additional companions residing in the system. Here we present a new adaptive optics assisted high-contrast imaging approach that takes advantage of the favourable planet spectral energy distribution at 4 mum, using narrow-band angular differential imaging to provide an improved contrast at small and intermediate separations from the star. We use this method to search for planets at orbits intermediate between epsilon Eri b (3.4 AU) and epsilon Eri c (40 AU). The method is described in detail, and important issues related to the detectability of planets such as the age of epsilon Eri and constraints from indirect measurements are discussed. The non-detection of companion candidates provides stringent upper limits for the masses of additional planets. Using a combination of the existing dynamic and imaging data, we exclude the presence of any planetary companion more massive than 3 M_{\rm jup} anywhere in the epsilon Eri system. Specifically, with regards to the possible residual linear radial velocity trend, we find that it is unlikely to correspond to a real physical companion if the system is as young as 200 Myr, whereas if it is as old as 800 Myr, there is an allowed semi-major axis range between about 8.5 and 25 AU.
ε Indi Ba,Bb: The nearest binary brown dwarf McCaughrean, M. J.; Close, L. M.; Scholz, R.-D. ...
Astronomy and astrophysics (Berlin),
01/2004, Letnik:
413, Številka:
3
Journal Article
Recenzirano
Odprti dostop
We have carried out high angular resolution near-infrared imaging and low-resolution ($R\sim1000$) spectroscopy of the nearest known brown dwarf, ε Indi B, using the ESO VLT NAOS/CONICA adaptive ...optics system. We find it to be a close binary (as also noted by Volk et al. 2003), with an angular separation of 0.732 arcsec, corresponding to 2.65 AU at the 3.626 pc distance of the ε Indi system. In our discovery paper (Scholz et al. 2003), we concluded that ε Indi B was a ~50 MJup T2.5 dwarf: our revised finding is that the two system components (ε Indi Ba and ε Indi Bb) have spectral types of T1 and T6, respectively, and estimated masses of 47 and 28 MJup , respectively, assuming an age of 1.3 Gyr. Errors in the masses are ±10 and ±7 MJup , respectively, dominated by the uncertainty in the age determination (0.8–2 Gyr range). This uniquely well-characterised T dwarf binary system should prove important in the study of low-mass, cool brown dwarfs. The two components are bright and relatively well-resolved: ε Indi B is the only T dwarf binary in which spectra have been obtained for both components. The system has a well-established distance and age. Finally, their orbital motion can be measured on a fairly short timescale (nominal orbital period ~15 yrs), permitting an accurate determination of the true total system mass, helping to calibrate brown dwarf evolutionary models.
Abstract Objectives Anemia is a frequent finding in older patients, associated with increased morbidity. Hematologic data of German geriatric inpatients are scarce. This cross-sectional multicenter ...study was issued by the German Geriatric Society to evaluate hematologic findings and possible causes of anemia in German geriatric inpatients. Methods Five hundred and seventy-nine geriatric inpatients, consecutively recruited in 6 participating German study centers; patient characteristics and laboratory parameters were obtained on admission. Inclusion criteria: geriatric in-patient ≥70 years; exclusion criteria: actual cancer disease or cancer associated treatment. Anemia definition according to WHO criteria. Definition of anemia severity according to National Cancer Institute reference values. Anemia subtypes were defined and divided into renal anemia, anemia of chronic diseases, iron deficiency anemia and anemia associated with vitamin B12 deficiency or deficiency of folic acid. Myelodysplastic syndrome (MDS) was suspected in case of anemia in combination with leucopenia or low platelets. Results Overall, prevalence of anemia was 55.1% (319/579 patients), mean serum hemoglobin value 11.9 g/dL. Anemia was mainly mild (72.7%) and normocytic (70.2%). MDS was suspected in 27 patients (8.5%), with 10 being macrocytic. Anemia of chronic diseases (ACD) was the most prevalent subtype of anemia (8.2%); multicausality can be assumed in many patients. MCV based classification was heterogenous in all anemia subtypes. Conclusion Anemia was mainly normocytic, mild and highly prevalent in this patient cohort, could not always be specified; multicausality was supposed; MCV appeared to be inappropriate for pathogenetical assignment of anemia subtypes in older patients. Further research in geriatric hematologic particularities is needed.
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