35,808 research outputs found
Crowding effects in vehicular traffic
While the impact of crowding on the diffusive transport of molecules within a
cell is widely studied in biology, it has thus far been neglected in traffic
systems where bulk behavior is the main concern. Here, we study the effects of
crowding due to car density and driving fluctuations on the transport of
vehicles. Using a microscopic model for traffic, we found that crowding can
push car movement from a superballistic down to a subdiffusive state. The
transition is also associated with a change in the shape of the probability
distribution of positions from negatively-skewed normal to an exponential
distribution. Moreover, crowding broadens the distribution of cars' trap times
and cluster sizes. At steady state, the subdiffusive state persists only when
there is a large variability in car speeds. We further relate our work to prior
findings from random walk models of transport in cellular systems.Comment: 23 pages, 11 figures, accepted for publication in PLoS ON
Widely separated binary systems of very low mass stars
In this paper we review some recent detections of wide binary brown dwarf
systems and discuss them in the context of the multiplicity properties of very
low-mass stars and brown dwarfs.Comment: 2 pages, 1 figure (new version with minor corrections); to appear in
the proceedings of the workshop "Ultra-low mass star formation and
evolution", to be published in A
Reversibility of Red blood Cell deformation
The ability of cells to undergo reversible shape changes is often crucial to
their survival. For Red Blood Cells (RBCs), irreversible alteration of the cell
shape and flexibility often causes anemia. Here we show theoretically that RBCs
may react irreversibly to mechanical perturbations because of tensile stress in
their cytoskeleton. The transient polymerization of protein fibers inside the
cell seen in sickle cell anemia or a transient external force can trigger the
formation of a cytoskeleton-free membrane protrusion of micrometer dimensions.
The complex relaxation kinetics of the cell shape is shown to be responsible
for selecting the final state once the perturbation is removed, thereby
controlling the reversibility of the deformation. In some case, tubular
protrusion are expected to relax via a peculiar "pearling instability".Comment: 4 pages, 3 figure
Measurement of Spin Polarization by Andreev Reflection in Ferromagnetic In1-xMnxSb Epilayers
We carried out Point Contact Andreev Reflection (PCAR) spin spectroscopy
measurements on epitaxially-grown ferromagnetic In1-xMnxSb epilayers with a
Curie temperature of ~9K. The spin sensitivity of PCAR in this material was
demonstrated by parallel control studies on its non-magnetic analog,
In1-yBeySb. We found the conductance curves of the Sn point contacts with
In1-yBeySb to be fairly conventional, with the possible presence of
proximity-induced superconductivity effects at the lowest temperatures. The
experimental Z-values of interfacial scattering agreed well with the estimates
based on the Fermi velocity mismatch between the semiconductor and the
superconductor. These measurements provided control data for subsequent PCAR
measurements on ferromagnetic In1-xMnxSb, which indicated spin polarization in
In1-xMnxSb to be 52 +- 3%
Discovery of Radio Emission from the Tight M8 Binary: LP 349-25
We present radio observations of 8 ultracool dwarfs with a narrow spectral
type range (M8-M9.5) using the Very Large Array at 8.5 GHz. Only the tight M8
binary LP 349-25 was detected. LP 349-25 is the tenth ultracool dwarf system
detected in radio and its trigonometric parallax pi = 67.6 mas, recently
measured by Gatewood et al., makes it the furthest ultracool system detected by
the Very Large Array to date, and the most radio-luminous outside of obvious
flaring activity or variability. With a separation of only 1.8 AU, masses of
the components of LP 349-25 can be measured precisely without any theoretical
assumptions (Forveille et al.), allowing us to clarify their fully-convective
status and hence the kind of magnetic dynamo in these components which may play
an important role to explain our detection of radio emission from these
objects. This also makes LP 349-25 an excellent target for further studies with
better constraints on the correlations between X-ray, radio emission and
stellar parameters such as mass, age, temperature, and luminosity in ultracool
dwarfs.Comment: accepted by ApJ, referee's comments included, typo in equation 1
correcte
Primary care summary of the British Thoracic Society Guidelines for the management of community acquired pneumonia in adults:2009 update. Endorsed by the Royal College of General Practitioners and the Primary Care Respiratory Society UK
The Brunei Bay as an Effluent Receiving Waterbody: Observations during the Start-up Period of a Kraft Pulp and Paper Mill
The water quality of Brunei Bay, Malaysia, subsequent to receiving iffluent from a pulp and paper mill,
was monitored. Conventional water quality parameters such as dissolved oxygen, suspended solids, and
biochemical oxygen demand were used as indicators to compare the present status of the bay water quality
with that of the baseline. Generally, data gathered during the first 16 months of the mill operation did not
indicate marked changes in the bay water quality. Levels of suspended solids, total organic carbons, and
1, 1-dichlorodimethyl sulfone in the bay water were used as indicators in the determination of dispersion
pattern of the effluent in the coastal areas of the bay
A participatory co-creation model to drive community engagement in rural indigenous schools:A case study in Sarawak
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