10,257 research outputs found
Mid-IR period-magnitude relations for AGB stars
Asymptotic Giant Branch variables are found to obey period-luminosity
relations in the mid-IR similar to those seen at K_S (2.14 microns), even at 24
microns where emission from circumstellar dust is expected to be dominant.
Their loci in the M, logP diagrams are essentially the same for the LMC and for
NGC6522 in spite of different ages and metallicities. There is no systematic
trend of slope with wavelength. The offsets of the apparent magnitude vs. logP
relations imply a difference between the two fields of 3.8 in distance modulus.
The colours of the variables confirm that a principal period with log P > 1.75
is a necessary condition for detectable mass-loss. At the longest observed
wavelength, 24 microns, many semi-regular variables have dust shells comparable
in luminosity to those around Miras. There is a clear bifurcation in LMC
colour-magnitude diagrams involving 24 micron magnitudes.Comment: 5 pages, 4 figure
A Critical Review of "Automatic Patch Generation Learned from Human-Written Patches": Essay on the Problem Statement and the Evaluation of Automatic Software Repair
At ICSE'2013, there was the first session ever dedicated to automatic program
repair. In this session, Kim et al. presented PAR, a novel template-based
approach for fixing Java bugs. We strongly disagree with key points of this
paper. Our critical review has two goals. First, we aim at explaining why we
disagree with Kim and colleagues and why the reasons behind this disagreement
are important for research on automatic software repair in general. Second, we
aim at contributing to the field with a clarification of the essential ideas
behind automatic software repair. In particular we discuss the main evaluation
criteria of automatic software repair: understandability, correctness and
completeness. We show that depending on how one sets up the repair scenario,
the evaluation goals may be contradictory. Eventually, we discuss the nature of
fix acceptability and its relation to the notion of software correctness.Comment: ICSE 2014, India (2014
X-ray rocking curve study of Si-implanted GaAs, Si, and Ge
Crystalline properties of Si-implanted GaAs, Si, and Ge have been studied by Bragg case double-crystal x-ray diffraction. Sharp qualitative and quantitative differences were found between the damage in GaAs on one hand and Si and Ge on the other. In Si and Ge the number of defects and the strain increase linearly with dose up to the amorphous threshold. In GaAs the increase in these quantities is neither linear nor monotonic with dose. At a moderate damage level the GaAs crystal undergoes a transition from elastic to plastic behavior. This transition is accompanied by the creation of extended defects, which are not detected in Si or Ge
Noise Effects on the Complex Patterns of Abnormal Heartbeats
Patients at high risk for sudden death often exhibit complex heart rhythms in
which abnormal heartbeats are interspersed with normal heartbeats. We analyze
such a complex rhythm in a single patient over a 12-hour period and show that
the rhythm can be described by a theoretical model consisting of two
interacting oscillators with stochastic elements. By varying the magnitude of
the noise, we show that for an intermediate level of noise, the model gives
best agreement with key statistical features of the dynamics.Comment: 4 pages, 4 figures, RevTe
Ultralow noise performance of an 8.4-GHz maser-feedhorn system
A total system noise temperature of 6.6 K was demonstrated with an 8.4-GHz traveling wave maser and feedhorn operating in a cryogenic environment. Both the maser and feedhorn were inserted in the helium cryostat, with the maser operating in the 1.6-K liquid bath and the feedhorn cooled in the helium gas, with a temperature gradient along the horn ranging from the liquid bath temperature at its lower end to room temperature at its top. The ruby maser exhibited 43 dB of gain with a bandwidth of 76 MHz(-3 dB) centered at 8400 MHz. Discussions of the maser, cooled feedhorn, and cryostat designs are presented along with a discussion of the noise temperature measurements
Enhanced response of the regular networks to local signals in presence of a fast impurity
We consider an array of inductively coupled Josephson junctions with a fast
impurity (a junction with a smaller value of critical current), and study the
consequences of imposing a small amplitude periodic signal at some point in the
array. We find that when external signal is imposed at the impurity, the
response of the array is boosted and a small amplitude signal can be detected
throughout the array. When the signal is imposed elsewhere, minor effects is
seen on the dynamics of the array. The same results have been also seen in
presence of a single fast spiking neuron in a chain of diffusively coupled
FitzHugh-Nagumo neurons.Comment: 6 pages, 5 figures, arXiv admin note: substantial text overlap with
arXiv:1108.460
The bulge luminosity functions in the MSX infrared bands
We use an inversion technique to derive the luminosity functions of the
Galactic bulge from point source counts extracted from the Midcourse Space
Experiment's Point Source Catalog (version 1.2).Comment: 5 pages, 2 figures, to be published in A&
Magnetovac Cylinder to Magnetovac Torus
A method for mapping known cylindrical magnetovac solutions to solutions in
torus coordinates is developed. Identification of the cylinder ends changes
topology from R1 x S1 to S1 x S1. An analytic Einstein-Maxwell solution for a
toroidal magnetic field in tori is presented. The toroidal interior is matched
to an asymptotically flat vacuum exterior, connected by an Israel boundary
layer.Comment: to appear in Class. Quant. Gra
ISOGAL Survey of Baade's Windows in the Mid-infrared
The ISOGAL mid-infrared survey of areas close to the Galactic Plane aims to
determine their stellar content and its possible bearing on the history of the
Galaxy. The NGC6522 and Sgr I Baade's Windows of low obscuration towards the
inner parts of the Bulge represent ideal places in which to calibrate and
understand the ISOGAL colour-magnitude diagrams.
The survey observations were made with the ISOCAM instrument of the ISO
satellite. The filter bands chosen were LW2(~7 microns) and LW3(~15 microns).
The results presented here show that most of the detected objects are late
M-type giants on the AGB, with a cut-off for those earlier than M3-M4. The most
luminous members of these two Bulge fields at 7 microns are the Mira variables.
However, it is evident that they represent the end of a sequence of increasing
15 micron dust emission which commences with M giants of earlier sub-type.
In observations of late-type giants the ISOCAM 15 micron band is mainly
sensitive to the cool silicate or aluminate dust shells which overwhelm the
photospheric emission. However, in ordinary M-giant stars, the 7 micron band is
not strongly affected by dust emission and may be influenced instead by
absorption. The nu2 band of water at 6.25 microns and the SiO fundamental at
7.9 microns are likely contribitors to this effect.
A group of late M stars has been found which vary little or not at all but
have infrared colours typical of well-developed dust shells. Their luminosities
are similar to those of 200-300 day Miras but they have slightly redder
[7]-[15] colours which form an extension of the ordinary M giant sequence.
The Mira dust shells show a mid-infrared [7]-[15] colour-period relation. ca
700 days.Comment: 13 pages 15 figure
A core genetic module : the Mixed Feedback Loop
The so-called Mixed Feedback Loop (MFL) is a small two-gene network where
protein A regulates the transcription of protein B and the two proteins form a
heterodimer. It has been found to be statistically over-represented in
statistical analyses of gene and protein interaction databases and to lie at
the core of several computer-generated genetic networks. Here, we propose and
mathematically study a model of the MFL and show that, by itself, it can serve
both as a bistable switch and as a clock (an oscillator) depending on kinetic
parameters. The MFL phase diagram as well as a detailed description of the
nonlinear oscillation regime are presented and some biological examples are
discussed. The results emphasize the role of protein interactions in the
function of genetic modules and the usefulness of modelling RNA dynamics
explicitly.Comment: To be published in Physical Review
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