449 research outputs found
Two patients with ciguatera toxicity:A seafood poisoning in travellers to (sub) tropical areas
Two patients with ciguatera toxicity:A seafood poisoning in travellers to (sub) tropical areas
On the nature of the prototype LBV AG Carinae I. Fundamental parameters during visual minimum phases and changes in the bolometric luminosity during the S-Dor cycle
We present a detailed spectroscopic analysis of the luminous blue variable AG
Carinae during the last two visual minimum phases of its S-Dor cycle (1985-1990
and 2000-2003). The analysis reveals an overabundance of He, N, and Na, and a
depletion of H, C, and O, on the surface of AG Car, indicating the presence of
CNO-processed material. Furthermore, the ratio N/O is higher on the stellar
surface than in the nebula. We found that the minimum phases of AG Car are not
equal to each other, since we derived a noticeable difference between the
maximum effective temperature achieved during 1985-1990 (22,800 K) and
2000-2001 (17,000 K). While the wind terminal velocity was 300 km/s in
1985-1990, it was as low as 105 km/s in 2001. The mass-loss rate, however, was
lower from 1985-1990 (1.5 x 10^(-5) Msun/yr) than from 2000-2001 (3.7 x 10^(-5)
Msun/yr). We found that the wind of AG Car is significantly clumped (f=0.10 -
0.25) and that clumps must be formed deep in the wind. We derived a bolometric
luminosity of 1.5 x 10^6 Lsun during both minimum phases which, contrary to the
common assumption, decreases to 1.0 x 10^6 Lsun as the star moves towards
maximum flux in the V band. Assuming that the decrease in the bolometric
luminosity of AG Car is due to the energy used to expand the outer layers of
the star (Lamers 1995), we found that the expanding layers contain roughly 0.6
- 2 Msun. Such an amount of mass is an order of magnitude lower than the
nebular mass around AG Car, but is comparable to the nebular mass found around
lower-luminosity LBVs and to that of the Little Homunculus of Eta Car. If such
a large amount of mass is indeed involved in the S Dor-type variability, we
speculate that such instability could be a failed Giant Eruption, with several
solar masses never becoming unbound from the star.(abridged)Comment: 22 pages, 13 figures, ApJ in press. A high-resolution PDF version is
also available at http://www.mpifr-bonn.mpg.de/staff/jgroh/agcar.htm
A simple and fast method to exclude high Plasmodium falciparum parasitaemia in travellers with imported malaria
Background: Counts of malaria parasites in peripheral blood are important to assess severity of Plasmodium falciparum malaria. Thin and thick smears are routinely used for this purpose. Methods. In this study the Binax NOW® Malaria Test, an easy-to-perform rapid diagnostic test, with Histidine Rich Protein-2 (HRP-2) and aldolase as diagnostic markers, was used for semi-quantitative assessment of parasitaemia of P. faciparum. Results: In 257 patients with imported P. falciparum malaria, reactivity of aldolase increased with higher parasitaemia. In all patients with a parasitaemia above 50,000 asexual parasites/l (> 1%) co-reactivity of HRP-2 and aldolase was observed. Absence of aldolase reactivity in the presence of HRP-2 was a reliable predictive marker to exclude high (> 1%) parasitaemia in P. falciparum malaria. Conclusions: Assessment of HRP-2 and aldolase co-reactivity can be of help in clinical decision making in the acute care setting of returning travellers suspected of having malaria
The highly polarized open cluster Trumpler 27
We have carried out multicolor linear polarimetry (UBVRI) of the brightest
stars in the area of the open cluster Trumpler 27. Our data show a high level
of polarization in the stellar light with a considerable dispersion, from to . The polarization vectors of the cluster members appear to be
aligned. Foreground polarization was estimated from the data of some non-member
objects, for which two different components were resolved: the first one
associated with a dust cloud close to the Sun producing
and degrees, and a second component, the main source of
polarization for the cluster members, originated in another dust cloud, which
polarizes the light in the direction of degrees. From a detailed
analysis, we found that the two components have associated values for the first one, and for the other. Due the
difference in the orientation of both polarization vectors, almost 90 degrees
(180 degrees at the Stokes representation), the first cloud (
degrees) depolarize the light strongly polarized by the second one ( degrees).Comment: 12 Pages, 6 Figures, 2 tables (9 Pages), accepted for publication in
A
Neopterin and procalcitonin are suitable biomarkers for exclusion of severe Plasmodium falciparum disease at the initial clinical assessment of travellers with imported malaria
Background. Most clinicians in developed, non-malaria endemic countries have limited or no experience in making clinical assessments of malaria disease severity and subsequent decisions regarding the need for parenteral therapy or high-level monitoring in febrile patients with imported malaria. In the present study, the diagnostic accuracy of plasma soluble Triggering Receptor Expressed on Myeloid cells 1 (TREM-1), neopterin and procalcitonin levels as biomarkers for severe Plasmodium falciparum disease was evaluated in 104 travellers with imported malaria (26 patients with non-P. falciparum malaria, 64 patients with uncomplicated P. falciparum malaria and 14 patients with severe P. falciparum malaria). Methods. TREM-1, neopterin and procalcitonin were determined in serum using commercially available ELISA or EIA tests. The diagnostic performance of these biomarkers for severe disease was compared with plasma lactate, a well-validated parameter for disease severity in patients with malaria, as reference. Severe malaria was defined according to the modified WHO criteria. Results. No significant differences in TREM-1 levels were detected between the different patient groups. Patients with severe P. falciparum malaria had significantly higher neopterin and procalcitonin levels on admission when compared to patients with uncomplicated P. falciparum malaria or non-P. falciparum malaria. Receiver Operating Characteristic (ROC) curve analysis showed that neopterin had the highest Area-Under-the-ROC curve (AUROC 0.85) compared with plasma lactate (AUROC 0.80) and procalcitonin (AUROC 0.78). At a cut-off point of 10.0 ng/ml, neopterin had a positive and negative predictive value of 0.38 and 0.98 whereas procalcitonin, at a cut-off point of 0.9 ng/ml, had a positive and negative predictive value of 0.30 and 1.00. Conclusion. Although the diagnostic value of neopterin and procalcitonin is limited, the high negative predictive value of both neopterin and procalcitonin may be helpful for a rapid exclusion of severe malaria disease on admission. This may be a valuable tool for physicians only occasionally dealing with ill-returned travellers from malaria-endemic regions and who need to decide on subsequent oral anti-malarial treatment or timely referral to a specialized centre for high-level monitoring and intensified parenteral treatment
Identification of the Infrared Counterpart to a Newly Discovered X-ray Source in the Galactic Center
We present first results of a campaign to find and identify new compact
objects in the Galactic Center. Selecting candidates from a combination of
Chandra and 2MASS survey data, we search for accretion disk signatures via
infrared spectroscopy. We have found the infrared counterpart to the Chandra
source CXO J174536.1-285638, the spectrum of which has strong Br-gamma and HeI
emission. The presence of CIII, NIII, and HeII indicate a binary system. We
suspect that the system is some form of high-mass binary system, either a
high-mass X-ray binary or a colliding wind binary.Comment: 11 pages, 6 figures, ApJ accepted, 200
Рівняння електромагнітної механіки пористого насиченого середовища
За двоконтинуумного наближення отримано повну систему співвідношень моделі електромагнітомеханіки статистично однорідного та ізотропного пористого насиченого середовища. Враховано наявність подвійного електричного шару в околі межі контакту твердої і рідкої фаз.Complete set of the model equations for electromagnetic mechanics of the porous saturated medium being statistically homogeneous and isotropic is obtained in two-continuum approximation. The presence of a double electrical layer in an environ of contact boundary of solid and liquid phases is taken into account.В двухконтинуумном приближении получено полную систему соотношений модели электромагнитомеханики статистически однородной и изотропной пористой насыщенной среды. Учтено наличие двойного электрического слоя в окрестности границы контакта твердой и жидкой фаз
The spectral variability and magnetic field characteristics of the Of?p star HD 148937
We report magnetic and spectroscopic observations and modeling of the Of?p
star HD 148937 within the context of the MiMeS LP at the CFHT. Thirty-two high
signal-to-noise ratio circularly polarised (Stokes V) spectra and 13
unpolarised (Stokes I) spectra of HD 148937 were acquired in 2009 and 2010. A
definite detection of a Stokes V Zeeman signature is obtained in the grand mean
of all observations (in both LSD mean profiles and individual spectral lines).
The longitudinal magnetic field inferred from the Stokes V LSD profiles is
consistently negative, in contrast to the essentially zero field strength
measured from the diagnostic null profiles. A period search of equivalent width
measurements confirms the previously-reported 7.03 d variability period. The
variation of equivalent widths is not strictly periodic: we present evidence
for evolution of the amount or distribution of circumstellar plasma.
Interpreting the 7.03 d period as the stellar rotational period within the
context of the ORM, we have phased the equivalent widths and longitudinal field
measurements. The longitudinal field measurements show a weak sinusoidal
variation of constant sign, with extrema out of phase with the H{\alpha}
variation by about 0.25 cycles. The inferred magnetic configuration confirms
the suggestion of Naz\'e et al (2010), who proposed that the weaker variability
of HD 148937 as compared to other members of this class is a consequence of the
stellar geometry. Based on the derived magnetic properties and published wind
characteristics, we find a wind magnetic confinement parameter \eta\ast \simeq
20 and rotation parameter W = 0.12, supporting a picture in which the Halpha
emission and other line variability have their origin in an oblique, rigidly
rotating magnetospheric structure resulting from a magnetically channeled wind.
(Abridged.)Comment: 13 pages, MNRAS. Version 2, small change to Fig. 1
I Zw 18 revisited with HST/ACS and Cepheids: New Distance and Age
We present new V and I-band HST/ACS photometry of I Zw 18, the most
metal-poor blue compact dwarf (BCD) galaxy in the nearby universe. It has been
argued in the past that I Zw 18 is a very young system that started forming
stars only 1 Gyr) red
giant branch (RGB) stars may also exist. Our new data, once combined with
archival HST/ACS data, provide a deep and uncontaminated optical
color-magnitude diagram (CMD) that now strongly indicates an RGB. The RGB tip
(TRGB) magnitude yields a distance modulus (m-M)_0 = 31.30 +/- 0.17, i.e., D =
18.2 +/- 1.5 Mpc. The time-series nature of our observations allows us to also
detect and characterize for the first time three classical Cepheids in I~Zw~18.
The time-averaged Cepheid and magnitudes are compared to the VI
reddening-free Wesenheit relation predicted from new non-linear pulsation
models specifically calculated at the metallicity of I Zw 18. For the one
bona-fide classical Cepheid with a period of 8.63 days this implies a distance
modulus (m-M)_0 = 31.42 +/- 0.26. The other two Cepheids have unusually long
periods (125.0 and 129.8 d) but are consistent with this distance. The coherent
picture that emerges is that I Zw 18 is older and farther away than previously
believed. This rules out the possibility that I Zw 18 is a truly primordial
galaxy formed recently (z < 0.1) in the local universe.Comment: 12 pages, 3 figures, submitted to ApJ
- …