901 research outputs found
CEO pay, shareholder returns, and accounting profits
We assess the impact on CEO pay (including salary, cash bonus, and benefits in kind) of changes in both accounting and shareholder returns in 99 British companies in the years 1972-89. After correcting for heterogeneity biases inherent in the standard specifications of the problem, we find a strong positive relationship between CEO pay and within-company changes in shareholder returns, and no statistically significant relationship between CEO pay and within-company changes in accounting returns. Differences between firms in long-term average profitability do appear to have a substantial effect on CEO pay, while differences between firms in shareholder returns add nothing to the within-firm pay dynamics.These findings call into question the rationale for explicitly share-based incentive schemes
Discovery of KiloHertz Quasi-Periodic Oscillations in the Z source Cygnus X-2
During observations with RXTE we discovered two simultaneous kHz QPOs near
500 Hz and 860 Hz in the Z source Cyg X-2. In the X-ray color-color diagram and
hardness-intensity diagram (HID) a clear Z track was traced out. A single kHz
QPO peak was detected at the left end of the horizontal branch (HB) of the Z
track, with a frequency of 731+/-20 Hz and an amplitude of 4.7+0.8-0.6 % rms in
the energy band 5.0-60 keV. Further to the right on the HB, at somewhat higher
count rates, an additional peak at 532+/-43 Hz was detected with an rms
amplitude of 3.0+1.0-0.7 %. When the source moved down the HB, thus when the
inferred mass accretion rate increased, the frequency of the higher-frequency
QPO increased to 839+/-13 Hz, and its amplitude decreased to 3.5+0.4-0.3 % rms.
The higher-frequency QPO was also detected on the upper normal branch (NB) with
an rms amplitude of 1.8+0.6-0.4 % and a frequency of 1007+/-15 Hz; its peak
width did not show a clear correlation with inferred mass accretion rate. The
lower-frequency QPO was most of the time undetectable, with typical upper
limits of 2 % rms, no conclusion on how this QPO behaved with mass accretion
rate can be drawn. If the peak separation between the QPOs is the neutron star
spin frequency (as required in some beat-frequency models) then the neutron
star spin period is 2.9+/-0.2 ms (346+/-29 Hz).Comment: 10 pages, including 3 figures. Accepted for publication in ApJ
Letter
Discovery of KiloHertz Quasi-Periodic Oscillations in 4U 1735-44
We discovered a single kHz quasi-periodic oscillation (QPO) near 1150 Hz in
the Rossi X-ray Timing Explorer X-ray light curve of the low mass X-ray binary
and atoll source 4U 1735-44. The rms amplitude of this peak was 2-3%, and the
FWHM 6-40 Hz. There are indications that the kHz QPO frequency decreased from
1160 Hz to 1145 Hz when the count rate increased, which would be quite
different from what is observed in other atoll sources for which kHz QPOs have
been discovered. In the X-ray color-color diagram and hardness-intensity
diagram the source traced out the curved branch (the so-called banana branch)
which has been found by previous instruments. The kHz QPO was only detected
when the source was at the lowest count rates during our observations, i.e. on
the lower part of the banana branch. When 4U 1735-44 was at higher count rates,
i.e. on the upper part of the banana branch and at higher inferred mass
accretion rate with respect to that on the lower part of the banana branch, the
QPO was not detected.
Besides the kHz QPO we discovered a low frequency QPO with a frequency near
67 Hz, together with a complex broad peaked noise component below 30 Hz. This
67 Hz QPO may be related to the magnetospheric beat-frequency QPO, which is
observed on the horizontal branch of Z sources. This idea is supported by the
(peaked) noise found in both 4U 1735-44 and Z sources at frequencies just below
the QPO frequency.Comment: 9 pages, including 2 figures. Accepted for publication in ApJ Letter
Kerlan-Jobe Orthopaedic Clinic overhead athlete scores in asymptomatic professional baseball pitchers.
BACKGROUND: The Kerlan-Jobe Orthopaedic Clinic (KJOC) Shoulder and Elbow score is a subjective questionnaire that has been validated and been shown to be more specific in overhead athletes than the American Shoulder and Elbow Surgeons scale. The purpose of this study was to determine a mean KJOC score and reasonable range of KJOC scores within which a healthy asymptomatic professional baseball pitcher will fall. It was hypothesized that healthy professional baseball pitchers would have very high KJOC scores.
MATERIALS AND METHODS: KJOC questionnaires were given to all healthy pitchers before the start of the season at all levels in 1 professional Minor League system. Pitchers were asked to complete the questionnaire upon reporting to their AAA, AA, or A affiliate team. Any pitcher starting the season on the disabled list was excluded from the study.
RESULTS: KJOC scores were returned by 44 pitchers. The mean score for all pitchers was 94.82 (95% confidence interval, 92.94-96.70). The mean score for each question was greater than 9 of 10. The mean score for the AAA affiliate was significantly higher than that for the AA affiliate (P = .015). No other significant differences in scores were found between class levels or groups based on professional playing experience.
CONCLUSION: Only 7 of 44 healthy asymptomatic pitchers (16%) had a KJOC score below 90. Therefore, we believe that the KJOC score is an accurate assessment for overhead athletes and normal values should be greater than 90. Anything below this value could be a potential cause for concern for team physicians.
LEVEL OF EVIDENCE: Basic Science, Survey Study, Healthy Subjects
Discovering and comparing types of general practitioner practices using geolocational features and prescribing behaviours by means of K-means clustering:A Comparison of Prescribing Behaviours Between Practice Types
Development And Field Application Of A Single Rotor Design Dry Gas Seal.
LecturePg. 107-116Improving centrifugal compressor seal performance and reliability can be accomplished through development of new technology and/or by improvement of existing technology. An improved dry gas lubricating seal of single rotor design has been designed for high pressure gas compressors. A more durable seal of simpler design has been created through implementation of ductile materials and reduction of components. Currently, the tandem dry gas seal configuration is the accepted standard for high pressure natural gas pipeline compressor applications. These applications still suffer problems with process and lube oil contamination, brittle fracture of carbide materials, and explosive decompression of 0-rings. Real costs associated with these problems are considerable. Development and potential benefits of the single rotor design seal, along with field application, in a high pressure natural gas centrifugal compressor is discussed
Patterns of avian diversification in Borneo: The case of the endemic Mountain Black-eye (Chlorocharis emiliae)
The Mountain Black-eye (Chlorocharis emiliae) is an endemic white-eye (Zosteropidae) of Borneo with a unique “sky island” distribution. We compared mitochondrial ND2, ND3, Cytb, and control region DNA sequences (2,194 nucleotides) to study the phylogeographic relationships of five populations of this species that span its range: Mounts Kinabalu, Trus Madi, Murud, Mulu, and Pueh. These comparisons showed that black-eyes are divided into two main clades that correspond generally to subspecific morphological groups: one in Sabah, Malaysia (Kinabalu and Trus Madi), and one in Sarawak, Malaysia (Murud, Mulu, and Pueh). The genetic and morphologic subdivision of black-eyes disputes the expected merging of populations during the Last Glacial Maximum (LGM), when montane forest presumably expanded and provided the opportunity for currently isolated populations to intermingle. Instead the genetic aging of black-eye populations indicates they diversified long before the LGM, and either did not expand sufficiently in range during the LGM to reach one another, or were reproductively isolated by the time of the LGM and thus prevented from interbreeding. Moreover, the subdivision between black-eyes in Sabah and Sarawak means that this species (and probably several other montane species) has a phylogeographic structure remarkably similar to Borneo's lowland bird populations, which are presumed to have evolved under different paleo-geographic conditions. The similar phylogeographic pattern found in both montane and lowland species requires that we rethink the causes of bird population diversification on the island of Borneo
Nitric oxide precursors and congenital heart surgery: A randomized controlled trial of oral citrulline
ObjectiveThe study sought to determine whether citrulline supplementation, a precursor to nitric oxide synthesis, is safe and efficacious in increasing plasma citrulline concentrations and decreasing the risk of postoperative pulmonary hypertension.Study DesignForty children, undergoing cardiopulmonary bypass and at risk for pulmonary hypertension, were randomized to receive 5 perioperative doses (1.9 g/m2 per dose) of either oral citrulline or placebo. Plasma citrulline and arginine concentrations were measured at 5 time points. Measurements of systemic blood pressure and presence of pulmonary hypertension were collected.ResultsMedian citrulline concentrations were significantly higher in the citrulline group versus the placebo group immediately postoperatively (36 μmol/L vs 26 μmol/L, P = .012) and at 12 hours postoperatively (37 μmol/L vs 20 μmol/L, P = .015). Mean plasma arginine concentrations were significantly higher in the citrulline group versus the placebo group by 12 hours postoperatively (36 μmol/L vs 23 μmol/L, P = .037). Mean systemic blood pressure did not differ between groups (P = .53). Postoperative pulmonary hypertension developed in 9 patients, 6 of 20 (30%) in the placebo group and 3 of 20 (15%) in the citrulline group (P = .451), all of whom had plasma citrulline concentrations less than age-specific norms. Postoperative pulmonary hypertension did not develop in patients who demonstrated plasma citrulline concentrations in excess of 37 μmol/L (P = .036).ConclusionsOral citrulline supplementation safely increased plasma citrulline and arginine concentrations compared with placebo after cardiopulmonary bypass. Postoperative pulmonary hypertension did not occur in children with naturally elevated citrulline levels or elevations through supplementation. Oral citrulline supplementation may be effective in reducing postoperative pulmonary hypertension
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