1,003 research outputs found
The GEEC2 spectroscopic survey of Galaxy Groups at
We present the data release of the Gemini-South GMOS spectroscopy in the
fields of 11 galaxy groups at , within the COSMOS field. This forms
the basis of the Galaxy Environment Evolution Collaboration 2 (GEEC2) project
to study galaxy evolution in haloes with across cosmic
time. The final sample includes spectroscopically--confirmed members with
per cent complete for galaxies within the virial
radius, and with stellar mass . Including
galaxies with photometric redshifts we have an effective sample size of galaxies within the virial radii of these groups. We present group
velocity dispersions, dynamical and stellar masses. Combining with the GCLASS
sample of more massive clusters at the same redshift we find the total stellar
mass is strongly correlated with the dynamical mass, with
. This stellar
fraction of per cent is lower than predicted by some halo occupation
distribution models, though the weak dependence on halo mass is in good
agreement. Most groups have an easily identifiable most massive galaxy (MMG)
near the centre of the galaxy distribution, and we present the spectroscopic
properties and surface brightness fits to these galaxies. The total stellar
mass distribution in the groups, excluding the MMG, compares well with an NFW
profile with concentration , for galaxies beyond . This is
more concentrated than the number density distribution, demonstrating that
there is some mass segregation.Comment: Accepted for publication in MNRAS. The appendix is omitted due to
large figures. The full version will be available from the MNRAS website and
from http://quixote.uwaterloo.ca/~mbalogh/papers/GEEC2_data.pdf. Long data
tables are available from MNRAS or by contacting the first autho
Spatiotemporal Variability and Sound Characterization in Silver Croaker Plagioscion squamosissimus (Sciaenidae) in the Central Amazon
Background
The fish family Sciaenidae has numerous species that produce sounds with superfast muscles that vibrate the swimbladder. These muscles form post embryonically and undergo seasonal hypertrophy-atrophy cycles. The family has been the focus of numerous passive acoustic studies to localize spatial and temporal occurrence of spawning aggregations. Fishes produce disturbance calls when hand-held, and males form aggregations in late afternoon and produce advertisement calls to attract females for mating. Previous studies on five continents have been confined to temperate species. Here we examine the calls of the silver croakerPlagioscion squamosissimus, a freshwater equatorial species, which experiences constant photoperiod, minimal temperature variation but seasonal changes in water depth and color, pH and conductivity. Methods and Principal Findings
Dissections indicate that sonic muscles are present exclusively in males and that muscles are thicker and redder during the mating season. Disturbance calls were recorded in hand-held fish during the low-water mating season and high-water period outside of the mating season. Advertisement calls were recorded from wild fish that formed aggregations in both periods but only during the mating season from fish in large cages. Disturbance calls consist of a series of short individual pulses in mature males. Advertisement calls start with single and paired pulses followed by greater amplitude multi-pulse bursts with higher peak frequencies than in disturbance calls. Advertisement-like calls also occur in aggregations during the off season, but bursts are shorter with fewer pulses. Conclusions and Significance
Silver croaker produce complex advertisement calls that vary in amplitude, number of cycles per burst and burst duration of their calls. Unlike temperate sciaenids, which only call during the spawning season, silver croaker produce advertisement calls in both seasons. Sonic muscles are thinner, and bursts are shorter than at the spawning peak, but males still produce complex calls outside of the mating season
Kinetics of the thermal decomposition of cellulose in sealed vessels at elevated pressures : Effects of the presence of water on the reaction mechanism
The thermal decomposition of Avicel cellulose was studied by non-isothermal differential scanning calorimetry in hermetically sealed sample holders. The experimental results, which were published earlier, showed a marked catalytic effect of the water on the cellulose decomposition. Here we propose a reaction scheme containing two rate determining reactions to describe the result. The corresponding model resulted in a good fit between the experimental and the calculated data. The results indicate that the reaction starts with cellulose hydrolysis which may be followed immediately by decomposition reactions to intermediate products. The intermediates undergo further water catalyzed decomposition reactions giving char, water and gases. The results may help to understand biomass pyrolysis under experimental or industrial conditions where the thickness of the layer, the size of particles or the enclosure of the reactor keeps part of the water vapors formed during the reaction in the pores or between the particles of the decomposing material
An Intermediate in the evolution of superfast sonic muscles.
Background
Intermediate forms in the evolution of new adaptations such as transitions from water to land and the evolution of flight are often poorly understood. Similarly, the evolution of superfast sonic muscles in fishes, often considered the fastest muscles in vertebrates, has been a mystery because slow bladder movement does not generate sound. Slow muscles that stretch the swimbladder and then produce sound during recoil have recently been discovered in ophidiiform fishes. Here we describe the disturbance call (produced when fish are held) and sonic mechanism in an unrelated perciform pearl perch (Glaucosomatidae) that represents an intermediate condition in the evolution of super-fast sonic muscles. Results
The pearl perch disturbance call is a two-part sound produced by a fast sonic muscle that rapidly stretches the bladder and an antagonistic tendon-smooth muscle combination (part 1) causing the tendon and bladder to snap back (part 2) generating a higher-frequency and greater-amplitude pulse. The smooth muscle is confirmed by electron microscopy and protein analysis. To our knowledge smooth muscle attachment to a tendon is unknown in animals. Conclusion
The pearl perch, an advanced perciform teleost unrelated to ophidiiform fishes, uses a slow type mechanism to produce the major portion of the sound pulse during recoil, but the swimbladder is stretched by a fast muscle. Similarities between the two unrelated lineages, suggest independent and convergent evolution of sonic muscles and indicate intermediate forms in the evolution of superfast muscles
Souvenaid in the Management of Mild Cognitive Impairment: An Expert Consensus Opinion
Background Mild cognitive impairment (MCI) among an aging global population is a growing challenge for healthcare providers and payers. In many cases, MCI is an ominous portent for dementia. Early and accurate diagnosis of MCI provides a window of opportunity to improve the outcomes using a personalized care plan including lifestyle modifications to reduce the impact of modifiable risk factors (for example, blood pressure control and increased physical activity), cognitive training, dietary advice, and nutritional support. Souvenaid is a once-daily drink containing a mixture of precursors and cofactors (long-chain omega-3 fatty acids, uridine, choline, B vitamins, vitamin C, vitamin E, and selenium), which was developed to support the formation and function of neuronal membranes and synapses. Healthcare providers, patients, and carers require expert advice about the use of Souvenaid. Methods An international panel of experts was convened to review the evidence and to make recommendations about the diagnosis and management of MCI, identification of candidates for Souvenaid, and use of Souvenaid in real-world practice. This article provides a summary of the expert opinions and makes recommendations for clinical practice and future research. Summary of opinion Early diagnosis of MCI requires the use of suitable neuropsychological tests combined with a careful clinical history. A multimodal approach is recommended; dietary and nutritional interventions should be considered alongside individualized lifestyle modifications. Although single-agent nutritional supplements have failed to produce cognitive benefits for patients with MCI, a broader nutritional approach warrants consideration. Evidence from randomized controlled trials suggests that Souvenaid should be considered as an option for some patients with early Alzheimer’s disease (AD), including those with MCI due to AD (prodromal AD). Conclusion Early and accurate diagnosis of MCI provides a window of opportunity to improve the outcomes using a multimodal management approach including lifestyle risk factor modification and consideration of the multinutrient Souvenaid
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