680 research outputs found
A systematic review and meta-analysis of the effectiveness of antiseptics for meatal cleaning in the prevention of catheter associated urinary tract infections
Background: Catheter-associated urinary tract infections (CAUTIs) are among the most common healthcare-associated infections. Antiseptic cleaning of the meatal area before and during catheter use may reduce the risk of CAUTIs.
Aim: To undertake a systematic review of the literature and meta-analysis of studies investigating the effectiveness of antiseptic cleaning before urinary catheter insertion and during catheter use for prevention of CAUTIs.
Methods: Electronic databases were searched to identify randomized controlled trials. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated and compared across intervention and control groups using DerSimonian–Laird random-effects model. Subgroup analyses were performed. Heterogeneity was estimated using the I2 statistic.
Findings: In total, 2665 potential papers were identified; of these, 14 studies were eligible for inclusion. There was no difference in the incidence of CAUTIs when comparing antiseptic and non-antiseptic agents (pooled OR 0.90, 95% CI 0.73–1.10; P=0.31), or when comparing different agents: povidone-iodine vs routine care; povidone-iodine vs soap and water; chlorhexidine vs water; povidone-iodine vs saline; povidone-iodine vs water; and green soap and water vs routine care (P > 0.05 for all). Comparison of an antibacterial agent with routine care indicated near significance (P=0.06). There was no evidence of heterogeneity (I2=0%; P > 0.05). Subgroup analyses showed no difference in the incidence of CAUTIs in terms of country, setting, risk of bias, sex and frequency of administration.
Conclusions: There were no differences in CAUTI rates, although methodological issues hamper generalizability of this finding. Antibacterial agents may prove to be significant in a well-conducted study. The present results provide good evidence to inform infection control guidelines in catheter management
Forty-seven Years of Research on the Devon Island Ice Cap, Arctic Canada
The Devon Island ice cap has been the subject of scientific study for almost half a century, beginning with the first mass balance measurements in 1961. Research on the ice cap was the first to investigate (1) the role of meltwater in seasonal ice-velocity variations on a polythermal Arctic ice cap, (2) the use of air temperature rather than net radiation as a proxy for the energy driving surface melt, and (3) the influence of the changing frequency of specific synoptic weather configurations on glacier melt and mass balance. Other research has included investigations of ice cap geometry, flow dynamics, and mass balance; ice core analyses for records of past climate and contaminant deposition; and studies of changes in ice cap area and volume and their relationship to surface mass balance and ice dynamics. Current research includes ground studies connected to efforts to calibrate and validate the radar altimeter that will be carried by the European Space Agency’s (ESA) CryoSat2 satellite, and a major collaborative Canadian International Polar Year (IPY) project focused on the Belcher Glacier, on the northeast side of the ice cap, that examines hydrodynamics of large tidewater glaciers. This paper summarizes our current knowledge of the Devon Island ice cap and identifies some of the outstanding questions that continue to limit our understanding of climate-ice cap interactions in Arctic regions.La calotte glaciaire de l’île Devon fait l’objet d’une étude scientifique depuis près d’un demi-siècle, les premières mesures du bilan massique remontant à 1961. C’est la première fois que des travaux de recherche sur la calotte glaciaire permettent de faire enquête sur 1) le rôle de l’eau de fonte dans les variations caractérisant la vélocité de la glace d’une calotte glaciaire polytherme de l’Arctique; 2) l’utilisation de la température de l’air au lieu du bilan radiatif en surface en guise d’approximation pour la fonte superficielle conductrice d’énergie, et 3) l’influence exercée par la fréquence changeante de configurations climatiques synoptiques spécifiques sur la fonte du glacier et le bilan massique. Parmi les autres travaux de recherche, notons des enquêtes sur la géométrie de la calotte glaciaire, la dynamique des débits d’écoulement et le bilan massique; l’analyse des enregistrements relatifs aux carottes glaciaires en ce qui a trait à d’anciens dépôts climatiques et dépôts de contaminants; et l’étude des changements caractérisant l’aire et le volume de la calotte glaciaire de même que leur relation par rapport au bilan massique en surface et à la dynamique des glaces. Par ailleurs, les travaux de recherche actuels prennent la forme d’études sur le terrain se rapportant aux efforts visant à calibrer et à valider l’altimètre radar, études qui seront effectuées par le satellite CryoSat2 de l’Agence spatiale européenne (ASE), et un projet d’envergure en collaboration avec l’Année polaire internationale (API) au Canada portant sur le glacier Belcher, du côté nord-est de la carotte glaciaire, projet qui examine l’hydrodynamique des gros glaciers de marée. La présente communication résume nos connaissances actuelles de la calotte glaciaire de l’île Devon de même que certaines des questions en suspens qui continuent de restreindre la façon dont nous comprenons les interactions entre le climat et la calotte glaciaire dans les régions arctiques
Hokupa'a-Gemini Discovery of Two Ultracool Companions to the Young Star HD 130948
We report the discovery of two faint ultracool companions to the nearby
(d~17.9 pc) young G2V star HD 130948 (HR 5534, HIP 72567) using the Hokupa'a
adaptive optics instrument mounted on the Gemini North 8-meter telescope. Both
objects have the same common proper motion as the primary star as seen over a 7
month baseline and have near-IR photometric colors that are consistent with an
early-L classification. Near-IR spectra taken with the NIRSPEC AO instrument on
the Keck II telescope reveal K I lines, FeH, and water bandheads. Based on
these spectra, we determine that both objects have spectral type dL2 with an
uncertainty of 2 spectral subclasses. The position of the new companions on the
H-R diagram in comparison with theoretical models is consistent with the young
age of the primary star (<0.8 Gyr) estimated on the basis of X-ray activity,
lithium abundance and fast rotation. HD 130948 B and C likely constitute a pair
of young contracting brown dwarfs with an orbital period of about 10 years, and
will yield dynamical masses for L dwarfs in the near future.Comment: 10 pages, 3 figures, (13 total pages
Covariant and Heavy Quark Symmetric Quark Models
There exist relativistic quark models (potential or MIT-bag) which satisfy
the heavy quark symmetry (HQS) relations among meson decay constants and form
factors. Covariant construction of the momentum eigenstates, developed here,
can correct for spurious center-of-mass motion contributions.Proton form factor
and M1 transitions in quarkonia are calculated. Explicit expression for the
Isgur-Wise function is found and model determined deviations from HQS are
studied. All results depend on the model parameters only. No additional ad hoc
assumptions are needed.Comment: 34 pages (2 figures not included but avaliable upon request), LATEX,
(to be published in Phys.Rev.D
Crystal-field ground state of the non-centrosymmetric superconductor CePt3Si: a combined polarized soft X-ray absorption and polarized neutron study
We determined the crystal-field split Hund's rule ground state of the
non-centrosymmetric heavy fermion superconductor CePt3Si with polarization
dependent soft X-ray absorption spectroscopy (XAS) and polarized neutron
scattering. We are also able to give the sequence of the crystal-field states
from the temperature evolution of the linear dichroic signal in the XAS. The
quantitative analysis of the XAS temperature dependence together with the
neutron transition energies complete the identification of the crystal-field
level scheme.Comment: 6 pages, 5 figures, submitted to PR
A circumstellar dust disk around T Tau N: Sub-arcsecond imaging at 3 mm
We present high-resolution imaging of the young binary T Tauri in 3 mm
continuum emission. Compact dust emission with integrated flux density 50 +/- 6
mJy is resolved in an aperture synthesis map at 0.5" resolution and is centered
at the position of the optically visible component, T Tau N. No emission above
a 3 sigma level of 9 mJy is detected 0.7" south of T Tau N at the position of
the infrared companion, T Tau S. We interpret the continuum detection as
arising from a circumstellar disk around T Tau N and estimate its properties by
fitting a flat-disk model to visibilities at wavelengths of 1 and 3 mm and to
the flux density at 7 mm. Given the data, probability distributions are
calculated for values of the free parameters, including the temperature,
density, dust opacity, and the disk outer radius. The radial variation in
temperature and density is not narrowly constrained by the data. The most
likely value of the frequency dependence of the dust opacity, beta =
0.53^{+0.27}_{-0.17}, is consistent with that of disks around other T Tauri
stars in which grain growth is believed to have taken place. The outer radius,
R = 41^{+26}_{-14} AU, is smaller than the projected binary separation, and may
indicate truncation of the disk. The total mass estimated for the disk,
log(M/M_sun) = {-2.4}^{+0.7}_{-0.6}, is similar to masses observed around many
young single sources and to the minimum nebular mass required to form a
planetary system like our own. This observation strongly suggests that the
presence of a binary companion does not rule out the formation of a sizeable
planetary system.Comment: Accepted by the Astrophysical Journal. 13 pages Latex (uses AASTeX
macros) including 3 postscript figures. Also at
http://astro.berkeley.edu/~rla
Glacier velocities and dynamic ice discharge from the Queen Elizabeth Islands, Nunavut, Canada
Recent studies indicate an increase in glacier mass loss from the Canadian Arctic Archipelago as a result of warmer summer air temperatures. However, no complete assessment of dynamic ice discharge from this region exists. We present the first complete surface velocity mapping of all ice masses in the Queen Elizabeth Islands and show that these ice masses discharged ~2.6 ± 0.8 Gt a−1 of ice to the oceans in winter 2012. Approximately 50% of the dynamic discharge was channeled through non surge-type Trinity and Wykeham Glaciers alone. Dynamic discharge of the surge-type Mittie Glacier varied from 0.90 ± 0.09 Gt a−1 during its 2003 surge to 0.02 ± 0.02 Gt a−1 during quiescence in 2012, highlighting the importance of surge-type glaciers for interannual variability in regional mass loss. Queen Elizabeth Islands glaciers currently account for ~7.5% of reported dynamic discharge from Arctic ice masses outside Greenland.We thank NSERC, Canada Foundation for Innovation, Ontario Research Fund, ArcticNet,
Ontario Graduate Scholarship, University of Ottawa and the NSERC Canada Graduate Scholarship for funding. RADARSAT-2 data were provided by MacDonald, Dettwiler and
Associates under the RADARSAT-2 Government Data Allocation administrated by the Canadian Space Agency. Support to DB is provided through the Climate Change Geosciences Program, Earth Sciences Sector, Natural Resources Canada (ESS Contribution #20130293). We also acknowledge support from U.K NERC for grants R3/12469 and NE/K004999 to JAD.This is the accepted version of an article published in Geophysical Research Letters. An edited version of this paper was published by AGU. Copyright (2014) American Geophysical Union. The final version is available at http://onlinelibrary.wiley.com/doi/10.1002/2013GL058558/abstract;jsessionid=6A3AD907C4383DA5D4E20C4924D6EC18.f02t02
Divergence of the Grueneisen Ratio at Quantum Critical Points in Heavy Fermion Metals
We present low-temperature volume thermal expansion, , and specific
heat, , measurements on high-quality single crystals of CeNi2Ge2 and
YbRh2(SiGe) which are located very near to quantum
critical points. For both systems, shows a more singular temperature
dependence than , and thus the Grueneisen ratio
diverges as T --> 0. For CeNi2Ge2, our results are in accordance with the
spin-density wave (SDW) scenario for three-dimensional critical
spin-fluctuations. By contrast, the observed singularity in
YbRh2_{0.95}_{0.05}_2$ cannot be explained by the itinerant SDW
theory but is qualitatively consistent with a locally quantum critical picture.Comment: 11 pages, 4 figure
HST/NICMOS Imaging of Disks and Envelopes Around Very Young Stars
We present HST/NICMOS observations with 0.1" (15 AU) resolution of six young
stellar objects in the Taurus star-formation region. The targets of our survey
are three Class I IRAS sources (IRAS 04016+2610, IRAS 04248+2612, and IRAS
04302+2247) and three low-luminosity stars (DG Tau B, Haro 6-5B, and CoKu
Tau/1) associated with Herbig Haro jets. The broad-band images show that the
near-infrared radiation from these sources is dominated by light scattered from
dusty circumstellar material distributed in a region 10 - 15 times the size of
our solar system. Although the detailed morphologies of the individual objects
are unique, the observed young stellar objects share common features. All of
the circumstellar reflection nebulae are crossed by dark lanes from 500 - 900
AU in extent and from less than 50 to 350 AU in apparent thickness. The
absorption lanes extend perpendicular to known optical and millimeter outflows
in these sources. We interpret the dark lanes as optically thick circumstellar
disks seen in silhouette against bright reflection nebulosity. The bipolar
reflection nebulae extending perpendicular to the dust lanes appear to be
produced by scattering from the upper and lower surfaces of the disks and from
dusty material within or on the walls of the outflow cavities. Out of five
objects in which the central source is directly detected, two are found to be
subarcsecond binaries. This mini-survey is the highest resolution near-infrared
study to date of circumstellar environments around solar-type stars with age <=
1 Myr.Comment: 34 pages, 4 figures; also available at
http://spider.ipac.caltech.edu/staff/brandner/topics/disks/disks.html ;
accepted for publication in AJ (March 1999 issue
Dust in the inner regions of debris disks around A stars
We present infrared interferometric observations of the inner regions of two
A-star debris disks, beta Leo and zeta Lep, using the FLUOR instrument at the
CHARA interferometer on both short (30 m) and long (>200 m) baselines. For the
target stars, the short baseline visibilities are lower than expected for the
stellar photosphere alone, while those of a check star, delta Leo, are not. We
interpret this visibility offset of a few percent as a near-infrared excess
arising from dust grains which, due to the instrumental field of view, must be
located within several AU of the central star. For beta Leo, the near-infrared
excess producing grains are spatially distinct from the dust which produces the
previously known mid-infrared excess. For zeta Lep, the near-infrared excess
may be spatially associated with the mid-infrared excess producing material. We
present simple geometric models which are consistent with the near and
mid-infrared excess and show that for both objects, the near-infrared producing
material is most consistent with a thin ring of dust near the sublimation
radius with typical grain sizes smaller than the nominal radiation pressure
blowout radius. Finally, we discuss possible origins of the near-infrared
emitting dust in the context of debris disk evolution models.Comment: 20 pages, 2 figures, to appear in the Astrophysical Journa
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