135 research outputs found
REMARKS ON HILL'S LUNAR THEORY. PART II
Remarks on hill lunar theory - part ii, direct lunar orbits as solutions to differential equatio
CALCULATION OF EPHEMERIDES FROM INITIAL VALUES
Calculation of ephemerides of planets and comets from initial value
Dietary supplementation of essential oils in dairy cows: evidence for stimulatory effects on nutrient absorption
Results of recent in vitro experiments suggest that essential oils (EO) may not only influence ruminal fermentation but also modulate the absorption of cations like Na+, Ca2+ and NH4+ across ruminal epithelia of cattle and sheep through direct interaction with epithelial transport proteins, such as those of the transient receptor potential family. The aim of the current study was to examine this hypothesis by testing the effect of a blend of essential oils (BEO) on cation status and feed efficiency in lactating dairy cows. In the experiment, 72 dairy cows in mid-to-end lactation were divided into two groups of 36 animals each and fed the same mixed ration with or without addition of BEO in a 2×2 cross-over design. Feed intake, milk yield and composition, plasma and urine samples were monitored. Feeding BEO elevated milk yield, milk fat and protein yield as well as feed efficiency, whereas urea levels in plasma and milk decreased. In addition, plasma calcium levels increased significantly upon BEO supplementation, supporting the hypothesis that enhanced cation absorption might contribute to the beneficial effects of these EO
Reporting of Sex Specific Outcomes in High Impact Orthopedic Journals
Background: There are known biologic differences between men and women that affect all aspects of health and disease, including in orthopedics. Hormonal regulation influences bone density, tissue structure, joint laxity, and muscle mass. Differences in anatomy and neuromuscular control have also been identified. While previous studies on disease incidences have shown certain conditions are more common in one sex (e.g., osteoarthritis in women), it is not routine practice to evaluate or publish outcomes based on sex.
Objectives: To evaluate the frequency with which papers in orthopedic journals published sex-specific outcomes with regard to knee osteoarthritis and rotator cuff pathology.
Methods: Four high-impact orthopedic journals were reviewed: Journal of Bone and Joint Surgery (JBJS), Clinical Orthopedics and Related Research (CORR), American Journal of Sports Medicine (AJSM), and Journal of Arthroplasty (JOA). JBJS and CORR were reviewed for rotator cuff and knee osteoarthritis. AJSM was reviewed for rotator cuff, while JOA was reviewed for knee osteoarthritis. 100 articles from each journal were reviewed. If there was any further analysis of sex beyond the statement of how many men and women were included in each group, a study was designated as successfully reporting sexspecific outcomes.
Results: 24-29% of rotator cuff articles reported on sex-specific outcomes. Sex specific outcomes were reported in 32-40% of knee osteoarthritis publications. Comparing rotator cuff to knee osteoarthritis articles, there was a trend toward more publications with sex-specific outcomes in knee osteoarthritis, however, this was not statistically significant (p = 0.0562). JBJS publishes significantly more articles reporting sex specific outcomes regarding knee osteoarthritis than rotator cuff (p= 0.0156).
Conclusions: Sex-specific outcomes are not widely reported in high-impact orthopedic journals. Sexspecific outcomes are reported more often in knee osteoarthritis where there are already well-known sexbased differences. To improve care, sex-specific outcomes should be reported across all orthopedic conditions.https://jdc.jefferson.edu/sexandgenderhealth/1028/thumbnail.jp
A Planet in a 0.6-AU Orbit Around the K0 Giant HD 102272
We report the discovery of one or more planet-mass companions to the K0-giant
HD 102272 with the Hobby-Eberly Telescope. In the absence of any correlation of
the observed periodicities with the standard indicators of stellar activity,
the observed radial velocity variations are most plausibly explained in terms
of a Keplerian motion of at least one planet-mass body around the star. With
the estimated stellar mass of 1.9M, the minimum mass of the confirmed
planet is 5.9M. The planet's orbit is characterized by a small but nonzero
eccentricity of =0.05 and the semi-major axis of 0.61 AU, which makes it the
most compact one discovered so far around GK-giants. This detection adds to the
existing evidence that, as predicted by theory, the minimum size of planetary
orbits around intermediate-mass giants is affected by both planet formation
processes and stellar evolution. The currently available evidence for another
planet around HD 102272 is insufficient to obtain an unambiguous two-orbit
solution.Comment: 10 pages, 5 figure
Fortnightly Fluctuations in the O-C Diagram of CS 1246
Dominated by a single, large-amplitude pulsation mode, the rapidly-pulsating
hot subdwarf B star CS 1246 is a prime candidate for a long-term O-C diagram
study. We collected nearly 400 hours of photometry with the PROMPT telescopes
over a time span of 14 months to begin looking for secular variations in the
pulse timings. Interestingly, the O-C diagram is dominated by a strong
sinusoidal pattern with a period of 14.1 days and an amplitude of 10.7
light-seconds. Underneath this sine wave is a secular trend implying a decrease
in the 371.7-s pulsational period of Pdot = -1.9 x 10^-11, which we attribute
to the evolution of the star through the H-R diagram. The sinusoidal variation
could be produced by the presence of a low-mass companion, with m sin i ~ 0.12
Msun, orbiting the subdwarf B star at a distance of 20 Rsun. An analysis of the
combined light curve reveals the presence of a low-amplitude first harmonic to
the main pulsation mode.Comment: Accepted for publication in MNRAS. 11 pages, 8 figures, 5 table
Pulsational Mapping of Calcium Across the Surface of a White Dwarf
We constrain the distribution of calcium across the surface of the white
dwarf star G29-38 by combining time series spectroscopy from Gemini-North with
global time series photometry from the Whole Earth Telescope. G29-38 is
actively accreting metals from a known debris disk. Since the metals sink
significantly faster than they mix across the surface, any inhomogeneity in the
accretion process will appear as an inhomogeneity of the metals on the surface
of the star. We measure the flux amplitudes and the calcium equivalent width
amplitudes for two large pulsations excited on G29-38 in 2008. The ratio of
these amplitudes best fits a model for polar accretion of calcium and rules out
equatorial accretion.Comment: Accepted to the Astrophysical Journal. 16 pages, 10 figures
The SEGUE Stellar Parameter Pipeline. III. Comparison with High-Resolution Spectroscopy of SDSS/SEGUE Field Stars
We report high-resolution spectroscopy of 125 field stars previously observed
as part of the Sloan Digital Sky Survey and its program for Galactic studies,
the Sloan Extension for Galactic Understanding and Exploration (SEGUE). These
spectra are used to measure radial velocities and to derive atmospheric
parameters, which we compare with those reported by the SEGUE Stellar Parameter
Pipeline (SSPP). The SSPP obtains estimates of these quantities based on SDSS
ugriz photometry and low-resolution (R = 2000) spectroscopy. For F- and G-type
stars observed with high signal-to-noise ratios (S/N), we empirically determine
the typical random uncertainties in the radial velocities, effective
temperatures, surface gravities, and metallicities delivered by the SSPP to be
2.4 km/s, 130 K (2.2%), 0.21 dex, and 0.11 dex, respectively, with systematic
uncertainties of a similar magnitude in the effective temperatures and
metallicities. We estimate random errors for lower S/N spectra based on
numerical simulations.Comment: 37 pages, 6 tables, 6 figures, submitted to the Astronomical Journa
Prime movers : mechanochemistry of mitotic kinesins
Mitotic spindles are self-organizing protein machines that harness teams of multiple force generators to drive chromosome segregation. Kinesins are key members of these force-generating teams. Different kinesins walk directionally along dynamic microtubules, anchor, crosslink, align and sort microtubules into polarized bundles, and influence microtubule dynamics by interacting with microtubule tips. The mechanochemical mechanisms of these kinesins are specialized to enable each type to make a specific contribution to spindle self-organization and chromosome segregation
Proteomic analysis of the Plasmodium male gamete reveals the key role for glycolysis in flagellar motility.
BACKGROUND: Gametogenesis and fertilization play crucial roles in malaria transmission. While male gametes are thought to be amongst the simplest eukaryotic cells and are proven targets of transmission blocking immunity, little is known about their molecular organization. For example, the pathway of energy metabolism that power motility, a feature that facilitates gamete encounter and fertilization, is unknown.
METHODS: Plasmodium berghei microgametes were purified and analysed by whole-cell proteomic analysis for the first time. Data are available via ProteomeXchange with identifier PXD001163.
RESULTS: 615 proteins were recovered, they included all male gamete proteins described thus far. Amongst them were the 11 enzymes of the glycolytic pathway. The hexose transporter was localized to the gamete plasma membrane and it was shown that microgamete motility can be suppressed effectively by inhibitors of this transporter and of the glycolytic pathway.
CONCLUSIONS: This study describes the first whole-cell proteomic analysis of the malaria male gamete. It identifies glycolysis as the likely exclusive source of energy for flagellar beat, and provides new insights in original features of Plasmodium flagellar organization
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