556 research outputs found
Planetary Bistatic Radar
Planetary radar observations offer the potential for probing the properties
of characteristics of solid bodies throughout the inner solar system and at
least as far as the orbit of Saturn. In addition to the direct scientific
value, precise orbital determinations can be obtained from planetary radar
observations, which are in turn valuable for mission planning or spacecraft
navigation and planetary defense. The next-generation Very Large Array would
not have to be equipped with a transmitter to be an important asset in the
world's planetary radar infrastructure. Bistatic radar, in which one antenna
transmits (e.g., Arecibo or Goldstone) and another receives, are used commonly
today, with the Green Bank Telescope (GBT) serving as a receiver. The improved
sensitivity of the ngVLA relative to the GBT would improve the signal-to-noise
ratios on many targets and increase the accessible volume specifically for
asteroids. Goldstone-ngVLA bistatic observations would have the potential of
rivaling the sensitivity of Arecibo, but with much wider sky access.Comment: 11 pages, 2 figures, To be published in the ASP Monograph Series,
"Science with a Next-Generation VLA", ed. E. J. Murphy (ASP, San Francisco,
CA
Maternal feeding practices, child eating behaviour and body mass index in preschool-aged children: a prospective analysis
<p>Abstract</p> <p>Background</p> <p>Previous research has found associations between parental feeding practices and children's eating behaviour and weight status. Prospective research is needed to elucidate these relationships.</p> <p>Methods</p> <p>One hundred and fifty-six mothers of 2- to 4-year-old children completed questionnaires including measures of maternal feeding practices (pressure to eat, restriction, monitoring and modelling of healthy eating), child eating behaviour (food responsiveness, food fussiness and interest in food), and mother reported child height and weight. The questionnaire was repeated 12 months later. Regression analyses were used to find longitudinal associations between maternal feeding practices, child eating behaviour and child body mass index (BMI).</p> <p>Results</p> <p>Modelling of healthy eating predicted lower child food fussiness and higher interest in food one year later, and pressure to eat predicted lower child interest in food. Restriction did not predict changes in child eating behaviour. Maternal feeding practices did not prospectively predict child food responsiveness or child BMI.</p> <p>Conclusion</p> <p>Maternal feeding practices appear to influence young children's eating behaviour but not weight status in the short term.</p
Burning mouth syndrome as the initial sign of multiple myeloma
AbstractA 79-year-old women was referred to our Department with burning symptoms in the whole oral cavity together with clinically healthy appearence of the oral mucosa. Hematological tests as well as bone marrow biopsy revealed diagnosis of plasmocytoma. The aim of our case report was to underline the importance of hematological screening in patients with burning mouth syndrome
Water-energy-food linkages in community smallholder irrigation schemes: Center pivot irrigation in Rwanda
Water, energy, and food are linked in intricate ways in irrigated agriculture and understanding the interplay of these components is crucial for sustainable and profitable crop production, particularly in smallholder setting such as in sub-Saharan Africa. This study evaluates water-energy-food linkages, engineering and economic performance, irrigation decision making, and challenges faced around water management in a community-based mechanized irrigation scheme in Rwanda. The research is the first to analyze such as scheme, which uses technology typically used by large farmers in a smallholder setting. The study investigates the variation in water requirements and the relationship and impacts of this variability on crop yield for the crops grown in the scheme: maize, French beans, and dry beans. Observed irrigation decision-making analyses demonstrate a lack of irrigation planning during growth stages and significant field-to-field variation in irrigation; this is linked to yield reduction in major crops. Results suggest that farmers irrigated only 31% of modeled irrigation water in dry beans and 27% of modeled irrigation water in maize. An econometric model assessment is used to understand the relationship between yield and energy inputs. A related policy analysis considers the impacts of changes in crop and water management on field-level profits and system-level financial sustainability. This study has implications for understanding irrigation policies in the context of the water-energy-food nexus and decision-making in Sub- Saharan Africa
Orbits of Near-Earth Asteroid Triples 2001 SN263 and 1994 CC: Properties, Origin, and Evolution
Three-body model fits to Arecibo and Goldstone radar data reveal the nature
of two near-Earth asteroid triples. Triple-asteroid system 2001 SN263 is
characterized by a primary of ~10^13 kg, an inner satellite ~1% as massive
orbiting at ~3 primary radii in ~0.7 days, and an outer satellite ~2.5% as
massive orbiting at ~13 primary radii in ~6.2 days. 1994 CC is a smaller system
with a primary of mass ~2.6 \times 10^11 kg and two satellites ~2% and ~1% as
massive orbiting at distances of ~5.5 and ~19.5 primary radii. Their orbital
periods are ~1.2 and ~8.4 days. Examination of resonant arguments shows that
the satellites are not currently in a mean-motion resonance. Precession of the
apses and nodes are detected in both systems (2001 SN263 inner body:
d{\varpi}/dt ~1.1 deg/day, 1994 CC inner body: d{\varpi}/dt ~ -0.2 deg/day),
which is in agreement with analytical predictions of the secular evolution due
to mutually interacting orbits and primary oblateness. Nonzero mutual
inclinations between the orbital planes of the satellites provide the best fits
to the data in both systems (2001 SN263: ~14 degrees, 1994 CC: ~16 degrees).
Our best-fit orbits are consistent with nearly circular motion, except for 1994
CC's outer satellite which has an eccentric orbit of e ~ 0.19. We examine
several processes that can generate the observed eccentricity and inclinations,
including the Kozai and evection resonances, past mean-motion resonance
crossings, and close encounters with terrestrial planets. In particular, we
find that close planetary encounters can easily excite the eccentricities and
mutual inclinations of the satellites' orbits to the currently observed values.Comment: 17 pages, accepted to Astronomical Journa
Factors associated with hospital readmission in sickle cell disease
<p>Abstract</p> <p>Background</p> <p>Sickle cell disease is the most frequent hereditary disease in Brazil, and people with the disease may be hospitalised several times in the course of their lives. The purpose of this study was to estimate the hazard ratios of factors associated with the time between hospital admissions.</p> <p>Methods</p> <p>The study sample comprised all patients admitted, from 2000 to 2004, to a university hospital in Rio de Janeiro State, south-east Brazil, as a result of acute complications from sickle cell disease (SCD). Considering the statistical problem of studying individuals with multiple events over time, the following extensions of Cox's proportional hazard ratio model were compared: the independent increment marginal model (Andersen-Gill) and the random effects model.</p> <p>Results</p> <p>The study considered 71 patients, who were admitted 223 times for acute events related to SCD. The hazard ratios for hospital readmission were statistically significant for the prior occurrence of vaso-occlusive crisis and development of renal failure. However, analysis of residuals of the marginal model revealed evidence of non-proportionality for some covariates.</p> <p>Conclusion</p> <p>the results from applying the two models were generally similar, indicating that the findings are not highly sensitive to different approaches. The better fit by the frailty model suggests that there are unmeasured individual factors with impact on hospital readmission.</p
Measurement of the Decay Amplitudes of B0 --> J/psi K* and B0s --> J/psi phi Decays
A full angular analysis has been performed for the pseudo-scalar to
vector-vector decays, B0 --> J/psi K* and B_s --> J/psi phi, to determine the
amplitudes for decays with parity-even longitudinal and transverse polarization
and parity-odd transverse polarization. The measurements are based on 190 B0
candidates and 40 B_s candidates collected from a data set corresponding to 89
inverse pb of pbarp collisions at root(s) = 1.8 TeV at the Fermilab Tevatron.
In both decays the decay amplitude for longitudinal polarization dominates and
the parity-odd amplitude is found to be small.Comment: 7 pages, 3 figures, 1 tabl
Measurement of J/Psi and Psi(2S) Polarization in ppbar Collisions at sqrt(s) = 1.8 TeV
We have measured the polarization of J/Psi and Psi(2S) mesons produced in
p\bar{p} collisions at \sqrt{s} = 1.8 TeV, using data collected at CDF during
1992-95.
The polarization of promptly produced J/Psi [Psi(2S)] mesons is isolated from
those produced in B-hadron decay, and measured over the kinematic range 4[5.5]
< P_T < 20 GeV/c and |y| < 0.6. For P_T \gessim 12 GeV/c we do not observe
significant polarization in the prompt component.Comment: Revised version, accepted for publication in Physical Review Letter
- …