2,528 research outputs found
The Gamma Ray Burst section of the White Paper on the Status and Future of Very High Energy Gamma Ray Astronomy: A Brief Preliminary Report
Original paper can be found at: http://proceedings.aip.org/proceedings/ Copyright American Institute of Physics DOI: 10.1063/1.2943545otherPeer reviewe
Albedo and Reflection Spectra of Extrasolar Giant Planets
We generate theoretical albedo and reflection spectra for a full range of
extrasolar giant planet (EGP) models, from Jovian to 51-Pegasi class objects.
Our albedo modeling utilizes the latest atomic and molecular cross sections, a
Mie theory treatment of extinction by condensates, a variety of particle size
distributions, and an extension of the Feautrier radiative transfer method
which allows for a general treatment of the scattering phase function. We find
that due to qualitative similarities in the compositions and spectra of objects
within each of five broad effective temperature ranges, it is natural to
establish five representative EGP albedo classes: a ``Jovian'' class (T K; Class I) with tropospheric ammonia clouds, a ``water
cloud'' class (T K; Class II) primarily affected by
condensed HO, a ``clear'' class (T K; Class III)
which lacks clouds, and two high-temperature classes: Class IV (900 K
T 1500 K) for which alkali metal absorption
predominates, and Class V (T 1500 K and/or low surface
gravity ( 10 cm s)) for which a high silicate layer
shields a significant fraction of the incident radiation from alkali metal and
molecular absorption. The resonance lines of sodium and potassium are expected
to be salient features in the reflection spectra of Class III, IV, and V
objects. We derive Bond albedos and effective temperatures for the full set of
known EGPs and explore the possible effects of non-equilibrium condensed
products of photolysis above or within principal cloud decks. As in Jupiter,
such species can lower the UV/blue albedo substantially, even if present in
relatively small mixing ratios.Comment: revised LaTeX manuscript accepted to Ap.J.; also available at
http://jupiter.as.arizona.edu/~burrows/paper
Trends in Caffeine Use and Association between Clinical Outcomes and Timing of Therapy in Very Low Birth Weight Infants
Objective: To examine the effect of early initiation of caffeine therapy on neonatal outcomes and characterize the use of caffeine therapy in very low birth weight (VLBW) infants.
Study design: We analyzed a cohort of 62 056 VLBW infants discharged between 1997 and 2010 who received caffeine therapy. We compared outcomes in infants receiving early caffeine therapy (initial dose before 3 days of life) and those receiving late caffeine therapy (initial dose at or after 3 days of life) through propensity scoring using baseline and early clinical variables. The primary outcome was the association between the timing of caffeine initiation and the incidence of bronchopulmonary dysplasia (BPD) or death.
Results: We propensity score–matched 29 070 VLBW infants at a 1:1. Of infants receiving early caffeine therapy, 3681 (27.6%) died or developed BPD, compared with 4591 infants (34.0%) receiving late caffeine therapy (OR, 0.74; 99% CI, 0.69-0.80). Infants receiving early caffeine had a lower incidence of BPD (23.1% vs 30.7%; OR, 0.68; 95% CI, 0.63-0.73) and a higher incidence of death (4.5% vs 3.7%; OR, 1.23; 95% CI, 1.05-1.43). Infants receiving early caffeine therapy had less treatment of patent ductus arteriosus (OR, 0.60; 95% CI, 0.55-0.65) and a shorter duration of mechanical ventilation (mean difference, 6 days; P \u3c .001).
Conclusion: Early caffeine initiation is associated with a decreased incidence of BPD. Randomized trials are needed to determine the efficacy and safety of early caffeine prophylaxis in VLBW infants. (J Pediatr 2014; 164:992-8)
Evaluation of Bovine chemerin (RARRES2) Gene Variation on Beef Cattle Production Traits1
A previous study in cattle based on >48,000 markers identified markers on chromosome 4 near the chemerin gene associated with average daily feed intake (ADFI) in steers (P < 0.008). Chemerin is an adipokine associated with obesity and metabolic syndrome in humans, representing a strong candidate gene potentially underlying the observed association. To evaluate whether the bovine chemerin gene is involved in feed intake, 16 markers within and around the gene were tested for association in the same resource population. Eleven were nominally significant for ADFI (P < 0.05) and two were significant after Bonferroni correction. Two and five SNP in this region were nominally significant for the related traits of average daily gain (ADG) and residual feed intake (RFI), respectively. All markers were evaluated for effects on meat quality and carcass phenotypes. Many of the markers associated with ADFI were associated with hot carcass weight (HCW), adjusted fat thickness (AFT), and marbling (P < 0.05). Marker alleles that were associated with lower ADFI were also associated with lower HCW, AFT, and marbling. Markers associated with ADFI were genotyped in a validation population of steers representing 14 breeds to determine predictive merit across populations. No consistent relationships for ADFI were detected. To determine whether cattle feed intake or growth phenotypes might be related to chemerin transcript abundance, the expression of chemerin was evaluated in adipose of 114 heifers that were siblings of the steers in the discovery population. Relative chemerin transcript abundance was not correlated with ADFI, ADG, or RFI, but associations with body condition score and yearling weight were observed. We conclude that variation in the chemerin gene may underlie observed association in the resource population, but that additional research is required to determine if this variation is widespread among breeds and to develop robust markers with predictive merit across breeds
Trends in Caffeine Use and Association between Clinical Outcomes and Timing of Therapy in Very Low Birth Weight Infants
Objective: To examine the effect of early initiation of caffeine therapy on neonatal outcomes and characterize the use of caffeine therapy in very low birth weight (VLBW) infants.
Study design: We analyzed a cohort of 62 056 VLBW infants discharged between 1997 and 2010 who received caffeine therapy. We compared outcomes in infants receiving early caffeine therapy (initial dose before 3 days of life) and those receiving late caffeine therapy (initial dose at or after 3 days of life) through propensity scoring using baseline and early clinical variables. The primary outcome was the association between the timing of caffeine initiation and the incidence of bronchopulmonary dysplasia (BPD) or death.
Results: We propensity score–matched 29 070 VLBW infants at a 1:1. Of infants receiving early caffeine therapy, 3681 (27.6%) died or developed BPD, compared with 4591 infants (34.0%) receiving late caffeine therapy (OR, 0.74; 99% CI, 0.69-0.80). Infants receiving early caffeine had a lower incidence of BPD (23.1% vs 30.7%; OR, 0.68; 95% CI, 0.63-0.73) and a higher incidence of death (4.5% vs 3.7%; OR, 1.23; 95% CI, 1.05-1.43). Infants receiving early caffeine therapy had less treatment of patent ductus arteriosus (OR, 0.60; 95% CI, 0.55-0.65) and a shorter duration of mechanical ventilation (mean difference, 6 days; P \u3c .001).
Conclusion: Early caffeine initiation is associated with a decreased incidence of BPD. Randomized trials are needed to determine the efficacy and safety of early caffeine prophylaxis in VLBW infants. (J Pediatr 2014; 164:992-8)
Defining a spinal microcircuit that gates myelinated afferent input: implications for tactile allodynia
Chronic pain presents a major unmet clinical problem. The development of more effective treatments is hindered by our limited understanding of the neuronal circuits underlying sensory perception. Here, we show that parvalbumin (PV)-expressing dorsal horn interneurons modulate the passage of sensory information conveyed by low-threshold mechanoreceptors (LTMRs) directly via presynaptic inhibition and also gate the polysynaptic relay of LTMR input to pain circuits by inhibiting lamina II excitatory interneurons whose axons project into lamina I. We show changes in the functional properties of these PV interneurons following peripheral nerve injury and that silencing these cells unmasks a circuit that allows innocuous touch inputs to activate pain circuits by increasing network activity in laminae I–IV. Such changes are likely to result in the development of tactile allodynia and could be targeted for more effective treatment of mechanical pain
Modeling of oropharyngeal articulatory adaptation to compensate for the acoustic effects of nasalization
Hypernasality is one of the most detrimental speech disturbances that lead to declines of speech intelligibility. Velopharyngeal inadequacy, which is associated with anatomic defects such as cleft palate or neuromuscular disorders that affect velopharygneal function, is the primary cause of hypernasality. A simulation study by Rong and Kuehn [J. Speech Lang. Hear. Res. 55(5), 1438–1448 (2012)] demonstrated that properly adjusted oropharyngeal articulation can reduce nasality for vowels synthesized with an articulatory model [Mermelstein, J. Acoust. Soc. Am. 53(4), 1070–1082 (1973)]. In this study, a speaker-adaptive articulatory model was developed to simulate speaker-customized oropharyngeal articulatory adaptation to compensate for the acoustic effects of nasalization on /a/, /i/, and /u/. The results demonstrated that (1) the oropharyngeal articulatory adaptation effectively counteracted the effects of nasalization on the second lowest formant frequency (F2) and partially compensated for the effects of nasalization on vowel space (e.g., shifting and constriction of vowel space) and (2) the articulatory adaptation strategies generated by the speaker-adaptive model might be more efficacious for counteracting the acoustic effects of nasalization compared to the adaptation strategies generated by the standard articulatory model in Rong and Kuehn. The findings of this study indicated the potential of using oropharyngeal articulatory adaptation as a means to correct maladaptive articulatory behaviors and to reduce nasalit
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