7,758 research outputs found
Pressure test analysis of 200-inch multicell test tank
Pressure test analysis for large multiple cell tank with sectioned ski
XMM-Newton observations of SNR 1987A. II. The still increasing X-ray light curve and the properties of Fe K lines
Aims. We report on the recent observations of the supernova remnant SNR 1987A
in the Large Magellanic Cloud with XMM-Newton. Carefully monitoring the
evolution of the X-ray light curve allows to probe the complex circumstellar
medium structure observed around the supernova progenitor star.
Methods. We analyse all XMM-Newton observations of SNR 1987A from January
2007 to December 2011, using data from the EPIC-pn camera. Spectra from all
epochs are extracted and analysed in a homogeneous way. Using a multi-shock
model to fit the spectra across the 0.2-10 keV band we measure soft and hard
X-ray fluxes with high accuracy. In the hard X-ray band we examine the presence
and properties of Fe K ines. Our findings are interpreted in the framework of a
hydrodynamics-based model.
Results. The soft X-ray flux of SNR 1987A continuously increased in the
recent years. Although the light curve shows a mild flattening, there is no
sudden break as reported in an earlier work, a picture echoed by a revision of
the Chandra light curve. We therefore conclude that material in the equatorial
ring and out-of-plane HII regions are still being swept-up. We estimate the
thickness of the equatorial ring to be at least 4.5x10^16 cm (0.0146 pc). This
lower limit will increase as long as the soft X-ray flux has not reached a
turn-over. We detect a broad Fe K line in all spectra from 2007 to 2011. The
widths and centroid energies of the lines indicate the presence of a collection
of iron ionisation stages. Thermal emission from the hydrodynamic model does
not reproduce the low-energy part of the line (6.4-6.5 keV), suggesting that
fluorescence from neutral and/or low ionisation Fe might be present.Comment: 4 pages, 3 figures, 2 tables. Accepted for publication in Astronomy
and Astrophysic
RXJ0123.4-7321, a Be/X-ray binary in the wing of the SMC
To confirm faint Be/X-ray binary candidates from the XMM-Newton survey of the
Small Magellanic Cloud, we searched for X-ray outbursts in archival ROSAT
observations. We found that RXJ0123.4-7321 was much brighter when detected with
ROSAT than seen 16 years later by XMM-Newton. We analysed the ROSAT
observations and the OGLE I-band light curve of the optical counterpart to
investigate the nature of the system. High long-term variability in the X-ray
flux of a factor of ~150 was found between the ROSAT and XMM-Newton detections,
indicating strong outburst activity during the ROSAT observations. The I-band
light curve reveals long-term variability and regular outbursts with a period
of (119.9+-2.5) days indicating the orbital period of the binary system. The
large X-ray flux variations and the properties of the optical counterpart
confirm RXJ0123.4-7321 as a new Be/X-ray binary in the wing of the Small
Magellanic Cloud.Comment: 5 pages, 8 figures, accepted for publication in A&
Feasibility of UV lasing without inversion in mercury vapor
We investigate the feasibility of UV lasing without inversion at a wavelength
of nm utilizing interacting dark resonances in mercury vapor. Our
theoretical analysis starts with radiation damped optical Bloch equations for
all relevant 13 atomic levels. These master equations are generalized by
considering technical phase noise of the driving lasers. From the Doppler
broadened complex susceptibility we obtain the stationary output power from
semiclassical laser theory. The finite overlap of the driving Gaussian laser
beams defines an ellipsoidal inhomogeneous gain distribution. Therefore, we
evaluate the intra-cavity field inside a ring laser self-consistently with
Fourier optics. This analysis confirms the feasibility of UV lasing and reveals
its dependence on experimental parameters.Comment: changes were made according to reviewer comments (accepted for
publication in JOSA B
Modeling the deposition of bioaerosols with variable size and shape in the human respiratory tract – A review
AbstractThe behavior of bioaerosol particles with various size and shape in the human respiratory tract was simulated by using a probabilistic model of the lung and an almost realistic mathematical approach to particle deposition. Results obtained from the theoretical computations clearly show that biogenic particle deposition in different lung compartments does not only depend on physical particle properties, but also on breathing mode (nose or mouth breathing) and inhalative flow rate (=tidal volume×breathing frequency/30). Whilst ultrafine (<100nm) and large (>5μm) particles tend to accumulate in the extrathoracic region and the uppermost airways of the tracheobronchial tree, particles with intermediate size are characterized by higher penetration depth, leading to their possible accumulation in the lung alveoli. Due to their deposition in deep lung regions and insufficient clearance, some bioaerosol particles may induce severe lung diseases ranging from infections, allergies, and toxic reactions to cancer
Self-recording portable soil penetrometer
A lightweight portable penetrometer for testing soil characteristics is described. The penetrometer is composed of a handle, data recording, and probe components detachably joined together. The data recording component has an easily removed recording drum which rotates according to the downward force applied on the handle, and a stylus means for marking the drum along its height according to the penetration depth of probe into the soil
Multi-wavelength properties of IGR J05007-7047 (LXP 38.55) and identification as a Be X-ray binary pulsar in the LMC
We report on the results of a 40 d multi-wavelength monitoring of the
Be X-ray binary system IGR J05007-7047 (LXP 38.55). During that period the
system was monitored in the X-rays using the Swift telescope and in the optical
with multiple instruments. When the X-ray luminosity exceeded erg/s
we triggered an XMM-Newton ToO observation. Timing analysis of the photon
events collected during the XMM-Newton observation reveals coherent X-ray
pulsations with a period of 38.551(3) s (1 {\sigma}), making it the 17
known high-mass X-ray binary pulsar in the LMC. During the outburst, the X-ray
spectrum is fitted best with a model composed of an absorbed power law () plus a high-temperature black-body (kT 2 keV) component. By
analysing 12 yr of available OGLE optical data we derived a 30.776(5) d
optical period, confirming the previously reported X-ray period of the system
as its orbital period. During our X-ray monitoring the system showed limited
optical variability while its IR flux varied in phase with the X-ray
luminosity, which implies the presence of a disk-like component adding cooler
light to the spectral energy distribution of the system.Comment: 11 pages, 11 figures, Accepted for publication in MNRA
The Role of Cytoplasmic mRNA Cap-Binding Protein Complexes in Trypanosoma brucei and Other Trypanosomatids.
Trypanosomatid protozoa are unusual eukaryotes that are well known for having unusual ways of controlling their gene expression. The lack of a refined mode of transcriptional control in these organisms is compensated by several post-transcriptional control mechanisms, such as control of mRNA turnover and selection of mRNA for translation, that may modulate protein synthesis in response to several environmental conditions found in different hosts. In other eukaryotes, selection of mRNA for translation is mediated by the complex eIF4F, a heterotrimeric protein complex composed by the subunits eIF4E, eIF4G, and eIF4A, where the eIF4E binds to the 5'-cap structure of mature mRNAs. In this review, we present and discuss the characteristics of six trypanosomatid eIF4E homologs and their associated proteins that form multiple eIF4F complexes. The existence of multiple eIF4F complexes in trypanosomatids evokes exquisite mechanisms for differential mRNA recognition for translation
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