6,882 research outputs found
Chandra Observations of the Northeastern Rim of the Cygnus Loop
We present results from spatially resolved spectral analyses of the
northeastern (NE) rim of the Cygnus Loop supernova remnant (SNR) based on two
Chandra observations. One pointing includes northern outermost
abundance-enhanced regions discovered by recent Suzaku observations, while the
other pointing is located on regions with "normal" abundances in the NE rim of
the Cygnus Loop. The superior spatial resolving power of Chandra allows us to
reveal that the abundance-enhanced region is concentrated in an about
200"-thickness region behind the shock front. We confirm absolute metal
abundances (i.e., relative to H) as well as abundance ratios between metals are
consistent with those of the solar values within a factor of about 2. Also, we
find that the emission measure in the region gradually decreases toward the
shock front. These features are in contrast with those of the ejecta fragments
around the Vela SNR, which leads us to believe that the abundance enhancements
are not likely due to metal-rich ejecta. We suggest that the origin of the
plasma in this region is the interstellar medium (ISM). In the "normal"
abundance regions, we confirm that abundances are depleted to the solar values
by a factor of about 5 that is not expected in the ISM around the Cygnus Loop.
Introduction of non-thermal emission in our model fitting can not naturally
resolve the abundance-depletion problem. The origin of the depletion still
remains as an open question.Comment: 18 pages, 6 figure
Metal Rich Plasma at the Center Portion of the Cygnus Loop
We observed the center portion of the Cygnus Loop supernova remnant with the
ASCA observatory. The X-ray spectrum of the center portion was significantly
different from that obtained at the North-East (NE) limb. The emission lines
from Si and S were quite strong while those of O and the continuum emission
were similar to those obtained at the NE limb. Based on the spectral analysis,
Si and S emission lines originated from a high-kTe and low ionization plasma
whereas O and most of the continuum emission arose from a low-kTe and high
ionization plasma. We suppose that Si and S emitting gas are present at the
interior of the Loop while O lines and continuum emission mainly arise from the
shell region. Therefore, we subtracted the spectrum of the NE limb from that of
the center. Obtained abundances of Si, S, and Fe were 4 1, 6 2, and
times higher than those of the cosmic abundances,
respectively, and are 40 times richer than those obtained at the NE limb.
These facts strongly support that some of the crude ejecta must be left at the
center portion of the Cygnus Loop. The low abundance of Fe relative to Si and S
suggests a type II SN with a massive progenitor star as the origin of the
Cygnus Loop.Comment: Accepted for Publications of the Astronomical Society of Japan, 40
pages, 12 Postscript figures, uses PASJ95.sty, PASJadd.sty, and psbox.st
Drosophila RecQ4 Is Directly Involved in Both DNA Replication and the Response to UV Damage in S2 Cells.
The RecQ4 protein shows homology to both the S.cerevisiae DNA replication protein Sld2 and the DNA repair related RecQ helicases. Experimental data also suggest replication and repair functions for RecQ4, but the precise details of its involvement remain to be clarified.Here we show that depletion of DmRecQ4 by dsRNA interference in S2 cells causes defects consistent with a replication function for the protein. The cells show reduced proliferation associated with an S phase block, reduced BrdU incorporation, and an increase in cells with a subG1 DNA content. At the molecular level we observe reduced chromatin association of DNA polymerase-alpha and PCNA. We also observe increased chromatin association of phosphorylated H2AvD--consistent with the presence of DNA damage and increased apoptosis.Analysis of DmRecQ4 repair function suggests a direct role in NER, as the protein shows rapid but transient nuclear localisation after UV treatment. Re-localisation is not observed after etoposide or Hâ‚‚Oâ‚‚ treatment, indicating that the involvement of DmRecQ4 in repair is likely to be pathway specific.Deletion analysis of DmRecQ4 suggests that the SLD2 domain was essential, but not sufficient, for replication function. In addition a DmRecQ4 N-terminal deletion could efficiently re-localise on UV treatment, suggesting that the determinants for this response are contained in the C terminus of the protein. Finally several deletions show differential rescue of dsRNA generated replication and proliferation phenotypes. These will be useful for a molecular analysis of the specific role of DmRecQ4 in different cellular pathways
Endotoxemia and human liver transplantation
Ninety liver transplantations were performed in 81 patients. Plasma endotoxin was measured preoperatively, at the end of the anhepatic phase, and on postoperative days 1, 3, and 7. The presence of high endotoxin levels preoperatively and at the end of the anhepatic period was associated with graft failure and a high mortality. Patients with primary nonfunction of their transplants typically had severe endotoxemia. Endotoxemia could be a cause rather than an effect of perioperative complications and graft loss
Static Equilibrium of the Triangular Running Skyline System: A Three Dimensionally Movable Cable System
The static equilibrium of the Triangular Running Skyline (TRS) system was tested using a reduced scale model to see if and to what degree the carriage location and line tensions at the spars differed from the theoretically predicted ones. TRS is one of the promising environmentally sound methods for accessing the forest. The model has a span of three meters so that all conditions can be dealt with on a laboratory basis. In this test, line lengths of this model system were designed to have unstretched lengths derived from the theory of elastic catenary, to have the carriage set at a designated position. Then, the measured positions of the carriage and line tensions were compared with those derived from the theory. The results proved that the horizontal positioning error of the carriage is smaller than its vertical positioning error and that the carriage tends to be lower than its theoretical value. The greater theoretical line tension causes the error in line tension to be larger and the line tension tends to be lower than the theoretical value. In order to obtain more accurate positioning of the carriage, it is necessary to take loosening of lines, guy lines of spars, etc. into account
The Radial Structure of the Cygnus Loop Supernova Remnant --- Possible evidence of a cavity explosion ---
We observed the North-East (NE) Limb toward the center region of the Cygnus
Loop with the ASCA Observatory. We found a radial variation of electron
temperature (kTe) and ionization timescale (log(\tau)) whereas no variation
could be found for the abundances of heavy elements. In this paper, we
re-analyzed the same data set and new observations with the latest calibration
files. Then we constructed the precise spatial variations of kTe, log(\tau),
and abundances of O, Ne, Mg, Si, and Fe over the field of view (FOV). We found
a spatial variation not only in kTe and in log(\tau) but also in most of heavy
elements. As described in Miyata et al. (1994), values of kTe increase and
those of log(\tau) decrease toward the inner region. We found that the
abundance of heavy elements increases toward the inner region. The radial
profiles of O, Ne, and Fe show clear jump structures at a radius of 0.9 Rs,
where Rs is the shock radius. Outside of 0.9 Rs, abundances of all elements are
constant. On the contrary, inside of 0.9 Rs, abundances of these elements are
20--30 % larger than those obtained outside of 0.9 Rs. The radial profile of
kTe also shows the jump structure at 0.9 Rs. This means that the hot and metal
rich plasma fills the volume inside of 0.9 Rs. We concluded that this jump
structure was the possible evidence for the pre-existing cavity produced by the
precursor. If the ejecta fills inside of 0.9 Rs, the total mass of the ejecta
was roughly 4\Msun. We then estimated the main-sequence mass to be roughly
15\Msun, which supports the massive star in origin of the Cygnus Loop supernova
remnant and the existence of a pre-existing cavity.Comment: 37 pages, 14 figures. Accepted for publication of Ap
Efektivitas Penggunaan Instagram sebagai Media Promosi Perpustakaan Universitas Kristen Petra
Penelitian ini bertujuan untuk mengetahui bagaimana efektivitas peng-gunaan Instagram sebagai media promosi perpustakaan Universitas Kristen Petra. Penelitian ini menggunakan jenis penelitian kualitatif dengan metode wawancara. Teknik yang digunakan dalam pengumpulan data adalah purposive sampling dan untuk menguji keabsahan data, penulis menggunakan teknik triangulasi sumber. Hasil penelitian ini menunjukkan bahwa perpustakaan Universitas Kristen Petra masih belum efektif dalam menggunakan Instagram sebagai media promosinya. Hal ini disebabkan karena Instagram perpustakaan Universitas Kristen Petra masih belum memberikan informasi yang diharapkan oleh pengunjung perpustakaan Universitas Kristen Petra
Interplay between Nitrogen Dopants and Native Point Defects in Graphene
To understand the interaction between nitrogen dopants and native point
defects in graphene, we have studied the energetic stability of N-doped
graphene with vacancies and Stone-Wales (SW) defect by performing the density
functional theory calculations. Our results show that N substitution
energetically prefers to occur at the carbon atoms near the defects, especially
for those sites with larger bond shortening, indicating that the defect-induced
strain plays an important role in the stability of N dopants in defective
graphene. In the presence of monovacancy, the most stable position for N dopant
is the pyridinelike configuration, while for other point defects studied (SW
defect and divacancies) N prefers a site in the pentagonal ring. The effect of
native point defects on N dopants is quite strong: While the N doping is
endothermic in defect-free graphene, it becomes exothermic for defective
graphene. Our results imply that the native point defect and N dopant attract
each other, i.e., cooperative effect, which means that substitutional N dopants
would increase the probability of point defect generation and vice versa. Our
findings are supported by recent experimental studies on the N doping of
graphene. Furthermore we point out possibilities of aggregation of multiple N
dopants near native point defects. Finally we make brief comments on the effect
of Fe adsorption on the stability of N dopant aggregation.Comment: 10 pages, 5 figures. Figure 4(g) and Figure 5 are corrected. One
additional table is added. This is the final version for publicatio
Kiso observations for 20 GRBs in HETE-2 era
We have established a GRB follow-up observation system at Kiso observatory
(Japan) in 2001. Since the east Asian area had been blank for the GRB follow-up
observational network, this observational system is very important in studying
the temporal and spectral evolution of early afterglows. Using this system, we
have performed quick observations for optical afterglows from early phase based
on HETE-2 and INTEGRAL alerts. Thanks to the quick follow-up observation
system, we have been able to use the Kiso observatory in 20 events, and conduct
their follow-up observations in optical and near infrared wavelengths.Comment: 5 pages, 4 figure. Accepted for publication into "il nuovo cimento".
Proceeding of the 4th Rome GRB conference, eds. L. Piro, L. Amati, S. Covino,
B. Gendr
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