92 research outputs found
The extent of metal enrichment from galactic winds during the Cosmic Dawn
One of the key processes driving galaxy evolution during the Cosmic Dawn is
supernova feedback. This likely helps regulate star formation inside of
galaxies, but it can also drive winds that influence the large-scale
intergalactic medium. Here, we present a simple semi-analytic model of
supernova-driven galactic winds and explore the contributions of different
phases of galaxy evolution to metal enrichment in the high-redshift (z > 6)
Universe. We show that models calibrated to the observed galaxy luminosity
function at z~6-8 have filling factors ~1% at z~6 and ~0.1% at z~12, with
different star formation prescriptions providing about an order of magnitude
uncertainty. Despite the small fraction of space filled by winds, these
scenarios still provide more than enough enriched volume to explain the
observed abundance of metal-line absorbers in quasar spectra at z > 5. We also
consider enrichment through winds driven by Pop III star formation in
minihaloes. We find that these can dominate the total filling factor at z > 10
and even compete with winds from normal galaxies at z~6, at least in terms of
the total enriched volume. But these regions have much lower overall
metallicities, because each one is generated by a small burst of star
formation. Finally, we show that Compton cooling of these supernova-driven
winds at z > 6 has only a small effect on the cosmic microwave background.Comment: 12 pages, 8 figures, submitted to MNRA
Simultaneous Screening of 24 Target Genes of Foodborne Pathogens in 35 Foodborne Outbreaks Using Multiplex Real-Time SYBR Green PCR Analysis
A set of 8 multiplex real-time SYBR Green PCR (SG-PCR) assays including 3 target primers and an internal amplification control (IAC) primer was simultaneously evaluated in 3 h or less with regard to detection of 24 target genes of 23 foodborne pathogens in 7 stool specimens of foodborne outbreak using a 96-well reaction plate. This assay, combined with DNA extraction (QIAamp DNA Stool Mini kit), offered detection of greater than 103-104 foodborne pathogens per g in stool specimens. The products formed were identified using melting point temperature (Tm) curve analysis. This assay was evaluated for the detection of foodborne pathogens in 33 out of 35 cases of foodborne outbreak, using 4 different PCR instruments in 5 different laboratories. No interference from the multiplex real-time SG-PCR assay, including IAC, was observed in stool specimens in any analysis. We found multiplex real-time SG-PCR assay for simultaneous detection of 24 target genes of foodborne pathogens to be comprehensive, rapid, inexpensive, accurate, of high selectivity, and good for screening probability
A CASE OF CORONAVIRUS DISEASE 2019 COMPLICATED BY VENTILATORASSOCIATED PNEUMONIA, LUNG ABSCESS, AND STAPHYLOCOCCUS AUREUS BACTEREMIA
Complications of healthcare-associated infections have been reported in patients with coronavirus disease 2019 (COVID-19). We encountered a case of ventilator-associated pneumonia and lung abscess, complicated with Staphylococcus aureus bacteremia and multiple abscesses, in a patient with COVID-19. Streptococci and anaerobes were cultured from the sputum, which was considered to be the causative organism of the lung abscess. In the management of severe COVID-19, care should be taken to prevent complications of healthcare-associated infections; when secondary respiratory tract infections are suspected, the presence of lung abscess and anaerobic culture should be considered
High Excitation Molecular Gas in the Galactic Center Loops; 12CO(J =2-1 and J =3-2) Observations
We have carried out 12CO(J =2-1) and 12CO(J =3-2) observations at spatial
resolutions of 1.0-3.8 pc toward the entirety of loops 1 and 2 and part of loop
3 in the Galactic center with NANTEN2 and ASTE. These new results revealed
detailed distributions of the molecular gas and the line intensity ratio of the
two transitions, R3-2/2-1. In the three loops, R3-2/2-1 is in a range from 0.1
to 2.5 with a peak at ~ 0.7 while that in the disk molecular gas is in a range
from 0.1 to 1.2 with a peak at 0.4. This supports that the loops are more
highly excited than the disk molecular gas. An LVG analysis of three
transitions, 12CO J =3-2 and 2-1 and 13CO J =2-1, toward six positions in loops
1 and 2 shows density and temperature are in a range 102.2 - 104.7 cm-3 and
15-100 K or higher, respectively. Three regions extended by 50-100 pc in the
loops tend to have higher excitation conditions as characterized by R3-2/2-1
greater than 1.2. The highest ratio of 2.5 is found in the most developed foot
points between loops 1 and 2. This is interpreted that the foot points indicate
strongly shocked conditions as inferred from their large linewidths of 50-100
km s-1, confirming the suggestion by Torii et al. (2010b). The other two
regions outside the foot points suggest that the molecular gas is heated up by
some additional heating mechanisms possibly including magnetic reconnection. A
detailed analysis of four foot points have shown a U shape, an L shape or a
mirrored-L shape in the b-v distribution. It is shown that a simple kinematical
model which incorporates global rotation and expansion of the loops is able to
explain these characteristic shapes.Comment: 59 pages, accepted to PAS
Wide post-common envelope binaries containing ultramassive white dwarfs: evidence for efficient envelope ejection in massive AGB stars
Post-common-envelope binaries (PCEBs) containing a white dwarf (WD) and a
main-sequence (MS) star can constrain the physics of common envelope evolution
and calibrate binary evolution models. Most PCEBs studied to date have short
orbital periods (d), implying relatively inefficient
harnessing of binaries' orbital energy for envelope expulsion. Here, we present
follow-up observations of five binaries from {\it Gaia} DR3 containing
solar-type MS stars and probable ultramassive WDs ()
with significantly wider orbits than previously known PCEBs, d. The WD masses are much higher than expected for systems formed via
stable mass transfer at these periods, and their near-circular orbits suggest
partial tidal circularization when the WD progenitors were giants. These
properties strongly suggest that the binaries are PCEBs. Forming PCEBs at such
wide separations requires highly efficient envelope ejection, and we find that
the observed periods can only be explained if a significant fraction of the
energy released when the envelope recombines goes into ejecting it. Our 1D
stellar models including recombination energy confirm prior predictions that a
wide range of PCEB orbital periods, extending up to months or years, can
potentially result from Roche lobe overflow of a luminous AGB star. This
evolutionary scenario may also explain the formation of several wide WD+MS
binaries discovered via self-lensing, as well as a significant fraction of
post-AGB binaries and barium stars.Comment: 21 pages, 10 figures, accepted to MNRA
Temperature and Density in the Foot Points of the Molecular Loops in the Galactic Center; Analysis of Multi-J Transitions of 12CO(J=1-0, 3-2, 4-3, 7-6), 13CO(J=1-0) and C18O(J=1-0)
Fukui et al. (2006) discovered two molecular loops in the Galactic center and
argued that the foot points of the molecular loops, two bright spots at both
loops ends, represent the gas accumulated by the falling motion along the
loops, subsequent to magnetic flotation by the Parker instability. We have
carried out sensitive CO observations of the foot points toward l=356 deg at a
few pc resolution in the six rotational transitions of CO; 12CO(J=1-0, 3-2,
4-3, 7-6), 13CO(J=1-0) and C18O(J=1-0). The high resolution image of 12CO
(J=3-2) has revealed the detailed distribution of the high excitation gas
including U shapes, the outer boundary of which shows sharp intensity jumps
accompanying strong velocity gradients. An analysis of the multi-J CO
transitions shows that the temperature is in a range from 30-100 K and density
is around 10^3-10^4 cm^-3, confirming that the foot points have high
temperature and density although there is no prominent radiative heating source
such as high mass stars in or around the loops. We argue that the high
temperature is likely due to the shock heating under C-shock condition caused
by the magnetic flotation. We made a comparison of the gas distribution with
theoretical numerical simulations and note that the U shape is consistent with
numerical simulations. We also find that the region of highest temperature of
~100 K or higher inside the U shape corresponds to the spur having an upward
flow, additionally heated up either by magnetic reconnection or bouncing in the
interaction with the narrow neck at the bottom of the U shape. We note these
new findings further reinforce the magnetic floatation interpretation.Comment: 40 pages, 23 figures, accepted by PASJ on Vol.62 No.
Calaxin is required for cilia-driven determination of vertebrate laterality
Sasaki, K., Shiba, K., Nakamura, A. et al. Calaxin is required for cilia-driven determination of vertebrate laterality. Commun Biol 2, 226 (2019). https://doi.org/10.1038/s42003-019-0462-
The fastest stars in the Galaxy
We report a spectroscopic search for hypervelocity white dwarfs (WDs) that
are runaways from Type Ia supernovae (SNe Ia) and related thermonuclear
explosions. Candidates are selected from Gaia data with high tangential
velocities and blue colors. We find six new runaways, including four stars with
radial velocities (RVs) and total space velocities
. These are most likely the surviving donors from
double-degenerate binaries in which the other WD exploded. The other two
objects have lower minimum velocities, , and may
have formed through a different mechanism, such as pure deflagration of a WD in
a Type Iax supernova. The four fastest stars are hotter and smaller than the
previously known "D stars," with effective temperatures ranging from
20,000 to 130,000 K and radii of . Three
of these have carbon-dominated atmospheres, and one has a helium-dominated
atmosphere. Two stars have RVs of and -- the
fastest systemic stellar RVs ever measured. Their inferred birth velocities,
, imply that both WDs in the progenitor binary
had masses . The high observed velocities suggest that a
dominant fraction of the observed hypervelocity WD population comes from
double-degenerate binaries whose total mass significantly exceeds the
Chandrasekhar limit. However, the two nearest and faintest D stars have the
lowest velocities and masses, suggesting that observational selection effects
favor rarer, higher-mass stars. A significant population of fainter low-mass
runaways may still await discovery. We infer a birth rate of D stars that
is consistent with the SN Ia rate. The birth rate is poorly constrained,
however, because the luminosities and lifetimes of stars are
uncertain.Comment: 26 pages, 17 figures. Accepted to OJ
Genetic variants in mannose receptor gene (MRC1) confer susceptibility to increased risk of sarcoidosis
<p>Abstract</p> <p>Background</p> <p>Mannose receptor (MR) is a member of the C-type lectin receptor family involved in pathogen molecular-pattern recognition and thought to be critical in shaping host immune response. The aim of this study was to investigate potential associations of genetic variants in the <it>MRC1 </it>gene with sarcoidosis.</p> <p>Methods</p> <p>Nine single nucleotide polymorphisms (SNPs), encompassing the <it>MRC1 </it>gene, were genotyped in a total of 605 Japanese consisting of 181 sarcoidosis patients and 424 healthy controls.</p> <p>Results</p> <p>Suggestive evidence of association between rs691005 SNP and risk of sarcoidosis was observed independent of sex and age in a recessive model (<it>P </it>= 0.001).</p> <p>Conclusions</p> <p>These results suggest that <it>MRC1 </it>is an important candidate gene for sarcoidosis. This is the first study to imply that genetic variants in <it>MRC1</it>, a major member of the C-type lectin, contribute to the development of sarcoidosis.</p
いい音・悪い音 : 音を目で見ると
When young, one of the authors heard someone say \u27In fact there\u27s little difference between the refreshing waterfall sound and the traffic noise on roads.\u27 So-called good sounds include insects\u27 chirping, tinkles of the wind-bell and piano tunes. Bad ones include noises of trams or machinery. What makes the difference between a \u27good sound\u27 and a \u27bad sound\u27? This paper intended to visually compare the frequencies of various sounds using Windows Media Player. The results obtained were as follows. 1. So-called good sounds generally had sharp fluctuations in their frequency ranges as shown on attached graphs. 2. So-called bad sounds had less sharp fluctuations in their frequency ranges, hence did not show a clear sound. 3. However, the fluctuations of the waterfall sound and the fluctuations of the traffic noise of the road were not very different, which suggests for some sounds the existence of other factors such as listeners\u27 psychology; memories of the past, the milieu and connotations
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