10,878 research outputs found
Tightly Correlated HI and FUV Emission in the Outskirts of M83
We compare sensitive HI data from The HI Nearby Galaxy Survey (THINGS) and
deep far UV (FUV) data from GALEX in the outer disk of M83. The FUV and HI maps
show a stunning spatial correlation out to almost 4 optical radii (r25),
roughly the extent of our maps. This underscores that HI traces the gas
reservoir for outer disk star formation and it implies that massive (at least
low level) star formation proceeds almost everywhere HI is observed. Whereas
the average FUV intensity decreases steadily with increasing radius before
leveling off at ~1.7 r25, the decline in HI surface density is more subtle. Low
HI columns (<2 M_solar/pc^2) contribute most of the mass in the outer disk,
which is not the case within r25. The time for star formation to consume the
available HI, inferred from the ratio of HI to FUV intensity, rises with
increasing radius before leveling off at ~100 Gyr, i.e., many Hubble times,
near ~1.7 r25. Assuming the relatively short H2 depletion times observed in the
inner parts of galaxies hold in outer disks, the conversion of HI into bound,
molecular clouds seems to limit star formation in outer galaxy disks. The long
consumption times suggest that most of the extended HI observed in M83 will not
be consumed by in situ star formation. However, even these low star formation
rates are enough to expect moderate chemical enrichment in a closed outer disk.Comment: Accepted for Publication in ApJ
Light hadron spectroscopy on the lattice with the non-perturbatively improved Wilson action
We present results for the light meson masses and decay constants as obtained
from calculations with the non-perturbatively improved (`Alpha') action and
operators on a 24^3 \times 64 lattice at beta = 6.2, in the quenched
approximation. The analysis was performed in a way consistent with O(a)
improvement. We obtained: reasonable agreement with experiment for the
hyperfine splitting; f_K=156(17) MeV, f_pi =139(22) MeV, f_K/f_pi = 1.13(4) ;
f_{K*}=219(7) MeV, f_rho =199(15) MeV, f_phi =235(4) MeV; f_{K*}^{T}(2 GeV) =
178(10) MeV, f_rho^{T}(2 GeV) =165(11) MeV, where f_V^{T} is the coupling of
the tensor current to the vector mesons; the chiral condensate
^\bar{MS} (2 GeV)= - (253 +/- 25 MeV)^3. Our results are compared to
those obtained with the unimproved Wilson action. We also verified that the
free-boson lattice dispersion relation describes our results very accurately
for a large range of momenta.Comment: 29 pages (LaTeX), 14 Postscript figure
Unusually Luminous Giant Molecular Clouds in the Outer Disk of M33
We use high spatial resolution (~7pc) CARMA observations to derive detailed
properties for 8 giant molecular clouds (GMCs) at a galactocentric radius
corresponding to approximately two CO scale lengths, or ~0.5 optical radii
(r25), in the Local Group spiral galaxy M33. At this radius, molecular gas
fraction, dust-to-gas ratio and metallicity are much lower than in the inner
part of M33 or in a typical spiral galaxy. This allows us to probe the impact
of environment on GMC properties by comparing our measurements to previous data
from the inner disk of M33, the Milky Way and other nearby galaxies. The outer
disk clouds roughly fall on the size-linewidth relation defined by
extragalactic GMCs, but are slightly displaced from the luminosity-virial mass
relation in the sense of having high CO luminosity compared to the inferred
virial mass. This implies a different CO-to-H2 conversion factor, which is on
average a factor of two lower than the inner disk and the extragalactic
average. We attribute this to significantly higher measured brightness
temperatures of the outer disk clouds compared to the ancillary sample of GMCs,
which is likely an effect of enhanced radiation levels due to massive star
formation in the vicinity of our target field. Apart from brightness
temperature, the properties we determine for the outer disk GMCs in M33 do not
differ significantly from those of our comparison sample. In particular, the
combined sample of inner and outer disk M33 clouds covers roughly the same
range in size, linewidth, virial mass and CO luminosity than the sample of
Milky Way GMCs. When compared to the inner disk clouds in M33, however, we find
even the brightest outer disk clouds to be smaller than most of their inner
disk counterparts. This may be due to incomplete sampling or a potentially
steeper cloud mass function at larger radii.Comment: Accepted for Publication in ApJ; 7 pages, 4 figure
New results from APE with non-perturbatively improved Wilson fermions
We present the results for light hadron spectrum, decay constants and the
quark masses obtained with non-perturbatively improved Wilson fermions. We also
give our preliminary results for the heavy-light decay constants.Comment: 3 pages, 2 figures, corrected some typos and one reference added,
LATTICE98(spectrum
Decays of Heavy Mesons
We present preliminary results for heavy to light transitions of pseudoscalar
mesons, induced by the vector and tensor operators. This lattice study is
performed in quenched approximation, by using the nonperturbatively improved
Wilson action and operators. We also update the values of the heavy-light meson
decay constants.Comment: LATT99(Heavy Quarks), 3 pages, 2 figure
Supporting play exploration and early developmental intervention versus usual care to enhance development outcomes during the transition from the neonatal intensive care unit to home: a pilot randomized controlled trial
Background While therapy services may start in the Neonatal Intensive Care Unit (NICU) there is often a gap in therapy after discharge. Supporting Play Exploration and Early Development Intervention (SPEEDI) supports parents, helping them build capacity to provide developmentally supportive opportunities starting in the NICU and continuing at home. The purpose of this single blinded randomized pilot clinical trial was to evaluate the initial efficacy of SPEEDI to improve early reaching and exploratory problem solving behaviors. Methods Fourteen infants born very preterm or with neonatal brain injury were randomly assigned to SPEEDI or Usual Care. The SPEEDI group participated in 5 collaborative parent, therapist, and infant interventions sessions in the NICU (Phase 1) and 5 at home (Phase 2). Parents provided daily opportunities designed to support the infants emerging motor control and exploratory behaviors. Primary outcome measures were assessed at the end of the intervention, 1 and 3 months after the intervention ended. Reaching was assessed with the infant supported in an infant chair using four 30 s trials. The Early Problem Solving Indicator was used to evaluate the frequency of behaviors during standardized play based assessment. Effect sizes are including for secondary outcomes including the Test of Infant Motor Performance and Bayley Scales of Infant and Toddler Development. Results No group differences were found in the duration of toy contact. There was a significant group effect on (F1,8 = 4.04, p = 0.08) early exploratory problem-solving behaviors with infants in the SPEEDI group demonstrating greater exploration with effect sizes of 1.3, 0.6, and 0.9 at the end of the intervention, 1 and 3 months post-intervention. Conclusions While further research is needed, this initial efficacy study showed promising results for the ability of SPEEDI to impact early problem solving behaviors at the end of intervention and at least 3 months after the intervention is over. While reaching did not show group differences, a ceiling effect may have contributed to this finding. This single blinded pilot RCT was registered prior to subject enrollment on 5/27/14 at ClinicalTrials.Gov with number NCT02153736
Identification of T-cell receptor a-chain genes in the chicken
T-cell receptor (TCR) -chain (TCR) and Ăź-chain (TCRĂź) genes are well characterized in mammals, while only TCRĂź genes have been identified in other vertebrates. To identify avian TCR genes, we used monoclonal anti-CD3 antibodies to isolate chicken TCR for peptide sequence analysis. Degenerate oligonucleotide probes were then used to isolate a candidate TCR cDNA clone that hybridized with a 1.7-kb mRNA species present only in Ăź T cells and in tissues populated by these cells. Southern blot analysis revealed gene rearrangement in thymocytes and Ăź T-cell lines. The TCR cDNA candidate encoded an openreading frame of 275 amino acids, the predicted variable (V)-, joining (J)-, and constant (C)-region amino acid sequences of which shared 40%, 60%, and 25% homology with corresponding mammalian sequences. A single C gene and 25 V genes were identified by using region-specific probes. The V cDNA probe isolated from a VĂź1+ cell line reacted with transcripts from one of five VĂź2+ cell lines, suggesting shared use of V genes by VĂź1+ and VĂź2+ T cells and the existence of other V gene families. A genomic V sequence was flanked by classical recombination signal sequences but, unlike previously defined V genes, the leader and V region were encoded by a single exon. The data indicate evolutionary conservation of the basic TCR gene structure in birds and mammal
Towards a Spatial Structure Plan for Sustainable Management of the Sea: Mixed actions - Final report: SPSD II (MA/02/006)
Microstructure Effects on Daily Return Volatility in Financial Markets
We simulate a series of daily returns from intraday price movements initiated
by microstructure elements. Significant evidence is found that daily returns
and daily return volatility exhibit first order autocorrelation, but trading
volume and daily return volatility are not correlated, while intraday
volatility is. We also consider GARCH effects in daily return series and show
that estimates using daily returns are biased from the influence of the level
of prices. Using daily price changes instead, we find evidence of a significant
GARCH component. These results suggest that microstructure elements have a
considerable influence on the return generating process.Comment: 15 pages, as presented at the Complexity Workshop in Aix-en-Provenc
The Molecular ISM of Dwarf Galaxies on Kiloparsec Scales: A New Survey for CO in Northern, IRAS-detected Dwarf Galaxies
We present a new survey for CO in dwarf galaxies using the Kitt Peak 12m
telescope. We observed the central regions of 121 northern dwarfs with IRAS
detections and no known CO emission. We detect CO in 28 of these galaxies and
marginally detect another 16, increasing by about 50% the number of such
galaxies known to have significant CO emission. The galaxies we detect are
comparable in mass to the LMC, although somewhat brighter in CO and fainter in
the FIR. Within dwarfs, we find that the CO luminosity, L_CO, is most strongly
correlated with the K-band and the far infrared luminosities. There are also
strong correlations with the radio continuum and B-band luminosities, and
linear diameter. We suggest that L_CO and L_K correlate well because the
stellar component of a galaxy dominates the midplane gravitational field and
thus sets the pressure of the atomic gas, which controls the formation of H_2
from HI. We compare our sample with more massive galaxies and find that dwarfs
and large galaxies obey the same relationship between CO and the 1.4 GHz radio
continuum (RC) surface brightness. This relationship is well described by a
Schmidt Law with Sigma_RC proportional to Sigma_CO^1.3. Therefore, dwarf
galaxies and large spirals exhibit the same relationship between molecular gas
and star formation rate (SFR). We find that this result is robust to moderate
changes in the RC-to-SFR and CO-to-H_2 conversion factors. Our data appear to
be inconsistent with large (order of magnitude) variations in the CO-to-H_2
conversion factor in the star forming molecular gas. [abridged]Comment: 28 pages, 14 figures, 5 tables, ApJ accepte
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