7,548 research outputs found
IRAC Observations of Taurus Pre-Main Sequence Stars
We present infrared photometry obtained with the IRAC camera on the Spitzer
Space Telescope of a sample of 82 pre-main sequence stars and brown dwarfs in
the Taurus star-forming region. We find a clear separation in some IRAC
color-color diagrams between objects with and without disks. A few
``transition'' objects are noted, which correspond to systems in which the
inner disk has been evacuated of small dust. Separating pure disk systems from
objects with remnant protostellar envelopes is more difficult at IRAC
wavelengths, especially for objects with infall at low rates and large angular
momenta. Our results generally confirm the IRAC color classification scheme
used in previous papers by Allen et al. and Megeath et al. to distinguish
between protostars, T Tauri stars with disks, and young stars without (inner)
disks. The observed IRAC colors are in good agreement with recent improved disk
models, and in general accord with models for protostellar envelopes derived
from analyzing a larger wavelength region. We also comment on a few Taurus
objects of special interest. Our results should be useful for interpreting IRAC
results in other, less well-studied star-forming regions.Comment: 29 pages 10 figures, to appear in Ap
Fabrication of One-Dimensional Programmable-Height Nanostructures via Dynamic Stencil Deposition
Dynamic stencil deposition (DSD) techniques offer a variety of fabrication
advantages not possible with traditional lithographic processing, such as the
the ability to directly deposit nanostructures with programmable height
profiles. However, DSD systems have not enjoyed widespread usage due to their
complexity. We demonstrate a simple, low-profile, portable, one-dimensional
nanotranslation system that facilitates access to nanoscale DSD abilities.
Furthermore we show a variety of fabricated programmable-height nanostructures,
including parallel arrays of such structures, and suggest other applications
that exploit the unique capabilities of DSD fabrication methods.Comment: 6 pages, 5 figure
New Eruptive YSOs from SPICY and WISE
© Published under Creative Commons license CC BY-SA 4.0.This work presents four high-amplitude variable YSOs (≃3 mag at near-or mid-IR wavelengths) arising from the SPICY catalog. Three outbursts show a duration that is longer than 1 year, and are still ongoing. And additional YSO brightened over the last two epochs of NEOWISE observations and the duration of the outburst is thus unclear. Analysis of the spectra of the four sources confirms them as new members of the eruptive variable class. We find two YSOs that can be firmly classified as bona fide FUors and one object that falls in the V1647 Ori-like class. Given the uncertainty in the duration of its outburst, an additional YSO can only be classified as a candidate FUor. Continued monitoring and follow-up of these particular sources is important to better understand the accretion process of YSOs.Peer reviewe
New Eruptive YSOs from SPICY and WISE
This work presents four high-amplitude variable YSOs ( 3 mag at near-
or mid-IR wavelengths) arising from the SPICY catalog. Three outbursts show a
duration that is longer than 1 year, and are still ongoing. And additional YSO
brightened over the last two epochs of NEOWISE observations and the duration of
the outburst is thus unclear. Analysis of the spectra of the four sources
confirms them as new members of the eruptive variable class. We find two YSOs
that can be firmly classified as bona fide FUors and one object that falls in
the V1647 Ori-like class. Given the uncertainty in the duration of its
outburst, an additional YSO can only be classified as a candidate FUor.
Continued monitoring and follow-up of these particular sources is important to
better understand the accretion process of YSOs.Comment: 10 pages, 10 figures, Accepted for publication at the Journal of the
Korean Astronomical Societ
Multilocus sequence typing (MLST) analysis of Vibrio cholerae O1 El Tor isolates from Mozambique that harbour the classical CTX prophage.
Vibrio cholerae O1 isolates belonging to the Ogawa serotype, El Tor biotype, harbouring the classical CTX prophage were first isolated in Mozambique in 2004. Multilocus sequence typing (MLST) analysis using nine genetic loci showed that the Mozambique isolates have the same sequence type (ST) as O1 El Tor N16961, a representative of the current seventh cholera pandemic. Analysis of the CTX prophage in the Mozambique isolates indicated that there is one type of rstR in these isolates: the classical CTX prophage. It was also found that the ctxB-rstR-rstA-rstB-phs-cep fragment was PCR-amplified from these isolates, which indicates the presence of a tandem repeat of the classical CTX prophage in the genome of the Mozambique isolates. The possible origin of these isolates and the presence of the tandem repeat of the classical prophage in them implicate the presence of the classical CTX phage
Operative outcome of hernia repair with synthetic mesh in immunocompromised patients
Background: The safety of synthetic mesh in elective hernia repair in the setting of immunosuppression lacks national and international consensus. The aim of our analysis was to explore the effects of immunosuppression on the rates of wound complications.
Methods: Comparative analysis of immunocompetent and immunocompromised patients with elective mesh repair of inguinal, femoral, primary ventral, incisional or parastomal hernia between January 2001 and December 2013. Immunosuppression included glucocorticoids, biologicals, chemotherapy and chemoradiotherapy. Primary outcome parameter was mesh infection rate. Follow-up questionnaires were completed in written form or by telephone interview.
Results: Questionnaire response rate was 59.5% (n= 194) with a median follow-up of 33 (interquartile range: 28-41) months. There were no differences between immunocompromised (n= 40, 20.6%) and immunocompetent patients (n= 154, 79.4%) based on hernia and patient characteristics. Immunosuppression was not associated with the rates of mesh infection (P= 1.000), surgical site infection (SSI,P= 0.330) or re-operation for SSI (P= 0.365), but with higher rates (P= 0.007) and larger odds for hernia recurrence (odds ratio 3.264, 95% confidence interval 1.304-8.172;P= 0.012). Mesh infection also increased the odds for hernia recurrence (odds ratio 11.625; 95% confidence interval 1.754-77.057;P= 0.011). Only in the subset of ventral/incisional hernias, immunocompromised (n= 8, 40%) patients had higher recurrence rates than immunocompetent patients (n= 5, 11.6%;P= 0.017). Patients with SSI reported more frequently moderate to severe dysesthesia at the surgical site (P= 0.013) and would less frequently re-consent to surgery (P= 0.006). Conclusion Immunosuppression does not increase the rate of wound infections after elective hernia repair with synthetic mesh. However, immunosuppression and mesh infection are risk factors for hernia recurrence
Contamination and exclusion in the sigma Orionis young group
We present radial velocities for 38 low-mass candidate members of the sigma
Orionis young group. We have measured their radial velocities by
cross-correlation of high resolution (R~6000) AF2/WYFFOS spectra of the gravity
sensitive NaI doublet at 8183, 8195Angstroms. The total sample contained 117
objects of which 54 have sufficient signal-to-noise to detect NaI at an
equivalent width of 3Angstroms, however we only detect NaI in 38 of these. This
implies that very low-mass members of this young group display weaker NaI
absorption than similarly aged objects in the Upper Scorpius OB association. We
develop a technique to assess membership using radial velocities with a range
of uncertainties that does not bias the selection when large uncertainties are
present. The resulting membership probabilities are used to assess the issue of
exclusion in photometric selections, and we find that very few members are
likely to be excluded by such techniques.
We also assess the level of contamination in the expected pre-main sequence
region of colour-magnitude space brighter than I = 17. We find that
contamination by non-members in the expected PMS region of the colour-magnitude
diagram is small. We conclude that although radial velocity alone is
insufficient to confirm membership, high signal-to-noise observations of the
NaI doublet provide the opportunity to use the strength of NaI absorption in
concert with radial velocities to asses membership down to the lowest masses,
where Lithium absorption no longer distinguishes youth.Comment: 11 pages, MNRAS accepted. Online data available from:
http://www.astro.ex.ac.uk/people/timn/Catalogues/service.htm
Fabrication and heating rate study of microscopic surface electrode ion traps
We report heating rate measurements in a microfabricated gold-on-sapphire
surface electrode ion trap with trapping height of approximately 240 micron.
Using the Doppler recooling method, we characterize the trap heating rates over
an extended region of the trap. The noise spectral density of the trap falls in
the range of noise spectra reported in ion traps at room temperature. We find
that during the first months of operation the heating rates increase by
approximately one order of magnitude. The increase in heating rates is largest
in the ion loading region of the trap, providing a strong hint that surface
contamination plays a major role for excessive heating rates. We discuss data
found in the literature and possible relation of anomalous heating to sources
of noise and dissipation in other systems, namely impurity atoms adsorbed on
metal surfaces and amorphous dielectrics.Comment: 17 pages, 5 figure
A shallow though extensive H2 2.12 micron imaging survey of Taurus-Auriga-Perseus: I. NGC1333, L1455, L1448 and B1
We discuss wide-field near-IR imaging of the NGC1333, L1448, L1455 and B1
star forming regions in Perseus. The observations have been extracted from a
much larger narrow-band imaging survey of the Taurus-Auriga-Perseus complex.
These H2 2.12 micron observations are complemented by broad-band K imaging,
mid-IR imaging and photometry from the Spitzer Space Telescope, and published
submillimetre CO J=3-2 maps of high-velocity molecular outflows. We detect and
label 85 H2 features and associate these with 26 molecular outflows. Three are
parsec-scale flows, with a mean flow lobe length exceeding 11.5 arcmin. 37
(44%) of the detected H2 features are associated with a known Herbig-Haro
object, while 72 (46%) of catalogued HH objects are detected in H2 emission.
Embedded Spitzer sources are identified for all but two of the 26 molecular
outflows. These candidate outflow sources all have high near-to-mid-IR spectral
indices (mean value of alpha ~ 1.4) as well as red IRAC 3.6-4.5 micron and
IRAC/MIPS 4.5-24.0 micron colours: 80% have [3.6]-[4.5] > 1.0 and [4.5]-[24] >
1.5. These criteria - high alpha and red [4.5]-[24] and [3.6]-[4.5] colours -
are powerful discriminants when searching for molecular outflow sources.
However, we find no correlation between alpha and flow length or opening angle,
and the outflows appear randomly orientated in each region. The more massive
clouds are associated with a greater number of outflows, which suggests that
the star formation efficiency is roughly the same in each region.Comment: 23 pages (including Appoendix); 11 main text figures, 5 colour
appendix figs uploaded as gifs; accepted by MNRAS; for higher-resolution
figures please visit http://www.jach.hawaii.edu/~cdavis
Epistemic Beliefs: Relationship to Future Expectancies and Quality of Life in Cancer Patients.
CONTEXT: Expectations about the future (future expectancies) are important determinants of psychological well-being among cancer patients, but the strategies patients use to maintain positive and cope with negative expectancies are incompletely understood.
OBJECTIVES: To obtain preliminary evidence on the potential role of one strategy for managing future expectancies: the adoption of epistemic beliefs in fundamental limits to medical knowledge.
METHODS: A sample of 1307 primarily advanced-stage cancer patients participating in a genomic tumor testing study in community oncology practices completed measures of epistemic beliefs, positive future expectancies, and mental and physical health-related quality of life (HRQOL). Descriptive and linear regression analyses were conducted to assess the relationships between these factors and test two hypotheses: 1) epistemic beliefs affirming fundamental limits to medical knowledge ( fallibilistic epistemic beliefs ) are associated with positive future expectancies and mental HRQOL, and 2) positive future expectancies mediate this association.
RESULTS: Participants reported relatively high beliefs in limits to medical knowledge (M = 2.94, s.d.=.67) and positive future expectancies (M = 3.01, s.d.=.62) (range 0-4), and relatively low mental and physical HRQOL. Consistent with hypotheses, fallibilistic epistemic beliefs were associated with positive future expectancies (b = 0.11, SE=.03, P\u3c 0.001) and greater mental HRQOL (b = 0.99, SE=.34, P = 0.004); positive expectancies also mediated the association between epistemic beliefs and mental HRQOL (Sobel Z=4.27, P\u3c0.001).
CONCLUSIONS: Epistemic beliefs in limits to medical knowledge are associated with positive future expectancies and greater mental HRQOL; positive expectancies mediate the association between epistemic beliefs and HRQOL. More research is needed to confirm these relationships and elucidate their causal mechanisms
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