1,951 research outputs found
The Walker Pass earthquakes and structure of the Southern Sierra Nevada
On March 15, 1946, a strong earthquake occurred in the Walker Pass area
of the southern Sierra Nevada. This earthquake and a large foreshock and
numerous aftershocks were well registered at Pasadena and its auxiliary stations
in southern California. Copies of records at Boulder City and Pierce
Ferry were kindly provided by the U. S. Coast and Geodetic Survey. Mr. S.
T. Martner and Mr. F. E. Lehner operated the portable seismometer to record
aftershocks at two localities: station No. 1, near Isabella, at 35° 39' 31" N,
118° 25' 45" W, and station No. 2, east of Mojave, at 35° 01'.0 N, 118 ° 01'.7 W
Instability of Quark Matter Core in a Compact Newborn Neutron Star With Moderately Strong Magnetic Field
It is explicitly shown that if phase transition occurs at the core of a
newborn neutron star with moderately strong magnetic field strength, which
populates only the electron's Landau levels, then in the -equilibrium
condition, the quark core is energetically much more unstable than the neutron
matter of identical physical condition.Comment: Six pages REVTEX file, one .eps file (included
Purification of Mixed State with Closed Timelike Curve is not Possible
In ordinary quantum theory any mixed state can be purified in an enlarged
Hilbert space by bringing an ancillary system. The purified state does not
depend on the state of any extraneous system with which the mixed state is
going to interact and on the physical interaction. Here, we prove that it is
not possible to purify a mixed state that traverses a closed time like curve
(CTC) and allowed to interact in a consistent way with a causality-respecting
(CR) quantum system in the same manner. Thus, in general for arbitrary
interactions between CR and CTC systems there is no universal 'Church of the
larger Hilbert space' for mixed states with CTC. This shows that in quantum
theory with CTCs there can exist 'proper' and 'improper' mixtures.Comment: Latex2e, No Figs, 4 + pages, An error corrected, Results unchange
Genetic differentiation of growth parameters in Brassica species
Fourteen collections from the Brassica species, B.Juncea, B. nap us, B. carinata and B. campestris showed substantial variability for growth parameters including vegetative (VPD) and reproductive phase (RPD) duration. In general, seed yield in all maturity groups was associated with growth parameters, particularly, VPD, RPD and flowering phase duration, for example, high yielders in the early maturity group and 60-75 days of VPD and 38-40 days of RPD. In contrast, those in the late maturity group had more than 100 days of VPD and relatively short, but varying RPD of 25-50 days. In the medium maturity group, high yields were often found to be associated with relatively long RPD. The yields of B. napus and B. carinata could be improved by shortening total crop duration and increasing RPD. Selection for optimal vegetative phase durations in the progeny of inter-specific hybrids could further improve the yields In Brassica
Genetic variability for plant type traits in Brassica species
Four species of Brassica viz., Brassica juncea, B. napus, B. carinata and B. campestris were evaluated over two years for plant type traits including basal branching. In B. juncea there was greater variation for plant height but not for seed yield. It was only next to B. campestris followed by B. napus for variation in basal branching trait. While, in B. campestris there was no genetic variation for basal branching trait, but it showed greater variation for days to flowering, total number of primary and secondary branches
Probing the effects of a thermonuclear X-ray burst on the neutron star accretion flow with NuSTAR
Observational evidence has been accumulating that thermonuclear X-ray bursts
ignited on the surface of neutron stars influence the surrounding accretion
flow. Here, we exploit the excellent sensitivity of NuSTAR up to 79 keV to
analyze the impact of an X-ray burst on the accretion emission of the neutron
star LMXB 4U 1608-52. The ~200 s long X-ray burst occurred during a hard X-ray
spectral state, and had a peak intensity of ~30-50 per cent of the Eddington
limit with no signs of photospheric radius expansion. Spectral analysis
suggests that the accretion emission was enhanced up to a factor of ~5 during
the X-ray burst. We also applied a linear unsupervised decomposition method,
namely non-negative matrix factorization (NMF), to study this X-ray burst. We
find that the NMF performs well in characterizing the evolution of the burst
emission and is a promising technique to study changes in the underlying
accretion emission in more detail than is possible through conventional
spectral fitting. For the burst of 4U 1608-52, the NMF suggests a possible
softening of the accretion spectrum during the X-ray burst, which could
potentially be ascribed to cooling of a corona. Finally, we report a small (~3
per cent) but significant rise in the accretion emission ~0.5 h before the
X-ray burst, although it is unclear whether this was related to the X-ray burst
ignition.Comment: 10 pages, 10 figures, 1 table, to appear in MNRA
Effect of magnetic field on the strange star
We study the effect of a magnetic field on the strage quark matter and apply
to strange star. We found that the strange star becomes more compact in
presence of strong magnetic field.Comment: 10 pages (LaTex) and 3 postscript figures available on reques
Chandra observations of the millisecond X-ray pulsar IGR J00291+5934 in quiescence
In this Paper we report on our analysis of three Chandra observations of the
accretion-powered millisecond X-ray pulsar IGR J00291+5934 obtained during the
late stages of the 2004 outburst. We also report the serendipitous detection of
the source in quiescence by ROSAT during MJD 48830-48839. The detected 0.3-10
keV source count rates varied significantly between the Chandra observations
from (7.2+-1.2)x10^-3, (6.8+-0.9)x10^-3, and (1.4+-0.1)x10^-2 counts per second
for the 1st, 2nd, and 3rd Chandra observation, on MJD 53371.88, 53383.99, and
53407.57, respectively. The count rate for the 3rd observation is 2.0+-0.4
times as high as that of the average of the first two observations. The
unabsorbed 0.5-10 keV source flux for the best-fit power-law model to the
source spectrum was (7.9+-2.5)x10^-14, (7.3+-2.0)x10^-14, and
(1.17+-0.22)x10^-13 erg cm^-2 s^-1 for the 1st, 2nd, and 3rd Chandra
observation, respectively. We find that this source flux is consistent with
that found by ROSAT [~(5.4+-2.4)x10^-14 erg cm^-2 s^-1]. Under the assumption
that the interstellar extinction, N_H, does not vary between the observations,
we find that the blackbody temperature during the 2nd Chandra observation is
significantly higher than that during the 1st and 3rd observation. Furthermore,
the effective temperature of the neutron star derived from fitting an absorbed
blackbody or neutron star atmosphere model to the data is rather high in
comparison with many other neutron star soft X-ray transients in quiescence,
even during the 1st and 3rd observation. If we assume that the source quiescent
luminosity is similar to that measured for two other accretion powered
millisecond pulsars in quiescence, the distance to IGR J00291+5934 is 2.6-3.6
kpc.Comment: 7 pages, 3 Figures, accepted for publication in MNRA
The Upper Limit of Magnetic Field Strength in Dense Stellar Hadronic Matter
It is shown that in strongly magnetized neutron stars, there exist upper
limits of magnetic field strength, beyond which the self energies for both
neutron and proton components of neutron star matter become complex in nature.
As a consequence they decay within the strong interaction time scale. However,
in the ultra-strong magnetic field case, when the zeroth Landau level is only
occupied by protons, the system again becomes stable against strong decay.Comment: 6 pages Revtex, 2 .eps figures, fig.(1) is not include
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