10,597 research outputs found
Lake Attitash Management Plan; 2010
Management Plan and Comprehensive Lake Inventory of Lake Attitash in Amesbury/ Merrimac, M
Electron collision cross sections in metal vapors Semiannual report
Electron collision cross section in metal vapors - measurement of Townsend alpha coefficient in cesium-helium mixture
A note on behaviour at an isotropic singularity
The behaviour of Jacobi fields along a time-like geodesic running into an
isotropic singularity is studied. It is shown that the Jacobi fields are
crushed to zero length at a rate which is the same in every direction
orthogonal to the geodesic. We show by means of a counter-example that this
crushing effect depends crucially on a technicality of the definition of
isotropic singularities, and not just on the uniform degeneracy of the metric
at the singularity.Comment: 13 pp. plain latex. To appear in Classical and Quantum Gravit
CCD photometry of 2060 Chiron, 1991 January
Observations of 2060 Chiron was performed on 7 to 8 Jan. 1991 with the Mt. Palomar 1.52 m telescope in the Gunn-R passband. On-chip field stars were used to perform differential reductions. The repeatability of the 5.9 hour light curve was excellent, both within a night and from night to night. No evidence for short-term secular variations similar to those seen last year by both Luu and Jewitt (1990) and Buratti and Dunbar (1991) is seen in the new light curve. Chiron's rotational light curve appears strikingly similar to that obtained a year earlier by Luu and Jewitt (1990), both in amplitude and shape. Both light curves show strongly correlated changes over a timescale of perhaps 15 minutes. These same features were marginally visible in the 1986 light curve. Such behavior is believed to be evidence that Chiron may be more aspherical than the 4 percent intensity variation might otherwise indicate, and favors a viewing geometry where the subearth latitude is rather low. Chiron was much fainter in 1985, when a partial light curve was obtained by Marcialis. Due to the lower sampling rate of these early data, no conclusions can be made regarding the high-frequency light curve structure back then. All three of these light curves differ significantly from that obtained by Buratti and Dunbar (1991), one week before the observations of Luu and Jewitt. The Chiron field was calibrated using Landolt standards on Ut 15 Mar. 1991. A mean R-magnitude of 15.6 + or - 0.1 was found. Variability of 2060 Chiron was demonstrated over timescales of minutes, hours, and years. An intense campaign was urged to monitor the photometric behavior of Chiron throughout the 1990s
Anesthesia Preoperative Clinic Referral for Elevated Hba1c Reduces Complication Rate in Diabetic Patients Undergoing Total Joint Arthroplasty
Background: Diabetes mellitus (DM) is risk factor for complications after orthopedic surgery.
Objectives: We tested the hypothesis that anesthesia preoperative clinic (APC) referral for elevated glycosylated hemoglobin (HbA1c) reduces complication rate after total joint arthroplasty (TJA).
Patients and Methods: Patients (n = 203) with and without DM were chosen from 1,237 patients undergoing TJA during 2006 - 12. Patients evaluated in the APC had surgery in 2006 - 8 regardless of HbA1c (uncontrolled). Those evaluated between in subsequent two-year intervals were referred to primary care for HbA1c ≥ 10% and ≥ 8%, respectively, to improve DM control before surgery. Complications and mortality were quantified postoperatively and at three, six, and twelve months. Length of stay (LOS) and patients requiring a prolonged LOS (\u3e 5 days) were recorded.
Results: Patients (197 men, 6 women) underwent 71, 131, and 1 total hip, knee, and shoulder replacements, respectively. Patients undergoing TJA with uncontrolled HbA1c and those with HbA1c \u3c 10%, but not those with HbA1c \u3c 8%, had a higher incidence of coronary disease and hypercholesterolemia than patients without DM. An increase in complication rate was observed in DM patients with uncontrolled HbA1c versus patients without DM (P \u3c 0.001); the complication rate progressively decreased with tighter HbA1c control. More DM patients with preoperative HbA1c that was uncontrolled or ≥ 10% required prolonged LOS versus those without DM (P \u3c 0.001 and P = 0.0404, respectively).
Conclusions: APC referral for elevated HbA1c reduces complication rate and the incidence of prolonged hospitalization during the first year after surgery in diabetics undergoing TJA
The star-formation histories of elliptical galaxies across the fundamental plane
We present the first results from a study designed to test whether, given
high-quality spectrophotometry spanning the mid-UV--optical wavelength regime,
it is possible to distinguish the metal content (Z) and star-formation history
(sfh) of individual elliptical galaxies with sufficient accuracy to establish
whether their formation history is linked to their detailed morphology and
position on the Fundamental Plane. From a detailed analysis of UV-optical
spectrophotometry of the `cuspy' elliptical galaxy NGC 3605 and the giant
elliptical NGC 5018 we find that: 1) optical spectra with l > 3500 A may not
contain sufficient data to robustly uncover all the stellar populations present
in individual galaxies, even in such relatively passive objects as ellipticals,
2) the addition of the UV data approaching l = 2500 A holds the key to
establishing well-constrained sfhs, from which we can infer a formation and
evolution history which is consistent with their photometric properties, 3)
despite the superficial similarity of their spectra, the two galaxies have very
different `recent' sfhs -- the smaller, cuspy elliptical NGC 3605 contains a
high-Z population of age ~= 1 Gyr, and has a position on the fundamental plane
typical of the product of a low-z gas-rich merger (most likely at z ~ 0.08),
while the giant elliptical NGC 5018, with a sub-solar secondary population,
appears to have gained its more recent stars via mass transfer / accretion of
gas from its spiral companion, 4) despite these differences in detailed
history, more than 85% of the stellar mass of both galaxies is associated with
an old (9-12 Gyr) stellar population of near-solar Z. This pilot study provides
strong motivation for the construction and analysis of high-quality UV-optical
spectra for a substantial sample of ellipticals spanning the Fundamental Plane.Comment: 11 pages, 10 figures, submitted to MNRAS, revised versio
Bulk and surface energetics of lithium hydride crystal: benchmarks from quantum Monte Carlo and quantum chemistry
We show how accurate benchmark values of the surface formation energy of
crystalline lithium hydride can be computed by the complementary techniques of
quantum Monte Carlo (QMC) and wavefunction-based molecular quantum chemistry.
To demonstrate the high accuracy of the QMC techniques, we present a detailed
study of the energetics of the bulk LiH crystal, using both pseudopotential and
all-electron approaches. We show that the equilibrium lattice parameter agrees
with experiment to within 0.03 %, which is around the experimental uncertainty,
and the cohesive energy agrees to within around 10 meV per formula unit. QMC in
periodic slab geometry is used to compute the formation energy of the LiH (001)
surface, and we show that the value can be accurately converged with respect to
slab thickness and other technical parameters. The quantum chemistry
calculations build on the recently developed hierarchical scheme for computing
the correlation energy of a crystal to high precision. We show that the
hierarchical scheme allows the accurate calculation of the surface formation
energy, and we present results that are well converged with respect to basis
set and with respect to the level of correlation treatment. The QMC and
hierarchical results for the surface formation energy agree to within about 1
%.Comment: 16 pages, 4 figure
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