6,052 research outputs found
Single-file diffusion on self-similar substrates
We study the single file diffusion problem on a one-dimensional lattice with
a self-similar distribution of hopping rates. We find that the time dependence
of the mean-square displacement of both a tagged particle and the center of
mass of the system present anomalous power laws modulated by logarithmic
periodic oscillations. The anomalous exponent of a tagged particle is one half
of the exponent of the center of mass, and always smaller than 1/4. Using
heuristic arguments, the exponents and the periods of oscillation are
analytically obtained and confirmed by Monte Carlo simulations.Comment: 12 pages, 6 figure
Critical Steps of Plasmodium falciparum Ookinete Maturation
The egress and fertilization of Plasmodium gametes and development of a motile ookinete are the first crucial steps that mediate the successful transmission of the malaria parasites from humans to the Anopheles vector. However, limited information exists about the cell biology and regulation of this process. Technical impediments in the establishment of in vitro conditions for ookinete maturation in Plasmodium falciparum and other human malaria parasites further constrain a detailed characterization of ookinete maturation. Here, using fluorescence microscopy and immunolabeling, we compared P. falciparum ookinete maturation in Anopheles coluzzii mosquitoes in vivo and in cell culture in vitro. Our results identified two critical steps in ookinete maturation that are regulated by distinct mosquito factors, thereby highlighting the role of the mosquito environment in the transmission efficiency of malaria parasites
A Statistical Analysis of the Solar Phenomena Associated with Global EUV Waves
Solar eruptions are the most spectacular events in our solar system and are
associated with many different signatures of energy release including solar
flares, coronal mass ejections, global waves, radio emission and accelerated
particles. Here, we apply the Coronal Pulse Identification and Tracking
Algorithm (CorPITA) to the high cadence synoptic data provided by the Solar
Dynamic Observatory (SDO) to identify and track global waves observed by SDO.
164 of the 362 solar flare events studied (45%) are found to have associated
global waves with no waves found for the remaining 198 (55%). A clear linear
relationship was found between the median initial velocity and the acceleration
of the waves, with faster waves exhibiting a stronger deceleration (consistent
with previous results). No clear relationship was found between global waves
and type II radio bursts, electrons or protons detected in-situ near Earth.
While no relationship was found between the wave properties and the associated
flare size (with waves produced by flares from B to X-class), more than a
quarter of the active regions studied were found to produce more than one wave
event. These results suggest that the presence of a global wave in a solar
eruption is most likely determined by the structure and connectivity of the
erupting active region and the surrounding quiet solar corona rather than by
the amount of free energy available within the active region.Comment: 33 pages, 6 figures, 1 table. Accepted for publication in Solar
Physic
ValoraciĂłn inicial del comportamiento de perros en un centro de recogida
Un grupo de 38 perros es valorado mediante un examen clĂnico estandarizado en el momento de la entrada y a los diez dĂas de la misma, no observándose diferencias significativas en la respuesta a dicho examen clĂnico, siendo 21% Y 15%, respectivamente, la presencia de comportamiento inadecuado
Detailed study of SNR G306.3-0.9 using XMM-Newton and Chandra observations
We used combined data from XMM-Newton and Chandra observatories to study the
X-ray morphology of SNR G306.3-0.9. A spatially-resolved spectral analysis was
used to obtain physical and geometrical parameters of different regions of the
remnant. Spitzer infrared observations were also used to constrain the
progenitor supernova and study the environment in which the SNR evolved. The
X-ray morphology of the remnant displays a non-uniform structure of
semi-circular appearance, with a bright southwest region and very weak or
almost negligible X-ray emission in its northern part. These results indicate
that the remnant is propagating in a non-uniform environment as the shock
fronts are encountering a high-density medium, where enhanced infrared emission
is detected. The X-ray spectral analysis of the selected regions shows distinct
emission-line features of several metal elements, confirming the thermal origin
of the emission. The X-ray spectra are well represented by a combination of two
absorbed thermal plasma models: one in equilibrium ionization with a mean
temperature of ~0.19 keV, and another out of equilibrium ionization at a higher
temperature of ~1.1 or 1.6-1.9 keV. For regions located in the northeast,
central, and southwest part of the SNR, we found elevated abundances of Si, S,
Ar, Ca, and Fe, typical of ejecta material. The outer regions located northwest
and south show values of the abundances above solar but lower than to those
found in the central regions. This suggests that the composition of the
emitting outer parts of the SNR is a combination of ejecta and shocked material
of the interstellar medium. The comparison between the S/Si, Ar/Si, and Ca/Si
abundances ratios (1.75, 1.27, and 2.72 in the central region, respectively),
favor a Type Ia progenitor for this SNR, a result that is also supported by an
independent morphological analysis using X-ray and IR data.Comment: 8 pages, 7 figures. Accepted by Astronomy and Astrophysic
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