1,879 research outputs found
ATLASGAL-selected massive clumps in the inner Galaxy: I. CO depletion and isotopic ratios
In the low-mass regime, it is found that the gas-phase abundances of
C-bearing molecules in cold starless cores rapidly decrease with increasing
density, as the molecules form mantles on dust grains. We study CO depletion in
102 massive clumps selected from the ATLASGAL 870 micron survey, and
investigate its correlation with evolutionary stage and with the physical
parameters of the sources. Moreover, we study the gradients in [12C]/[13C] and
[18O]/[17O] isotopic ratios across the inner Galaxy, and the virial stability
of the clumps. We use low-J emission lines of CO isotopologues and the dust
continuum emission to infer the depletion factor fD. RATRAN one-dimensional
models were also used to determine fD and to investigate the presence of
depletion above a density threshold. The isotopic ratios and optical depth were
derived with a Bayesian approach. We find a significant number of clumps with a
large fD, up to ~20. Larger values are found for colder clumps, thus for
earlier evolutionary phases. For massive clumps in the earliest stages of
evolution we estimate the radius of the region where CO depletion is important
to be a few tenths of a pc. Clumps are found with total masses derived from
dust continuum emission up to ~20 times higher than the virial mass, especially
among the less evolved sources. These large values may in part be explained by
the presence of depletion: if the CO emission comes mainly from the low-density
outer layers, the molecules may be subthermally excited, leading to an
overestimate of the dust masses. CO depletion in high-mass clumps seems to
behave as in the low-mass regime, with less evolved clumps showing larger
values for the depletion than their more evolved counterparts, and increasing
for denser sources. The C and O isotopic ratios are consistent with previous
determinations, and show a large intrinsic scatter.Comment: 20 pages, 17 figures, 38 pages of online material (tables and
figures
An Efficient Solution Method for Multibody Systems with Loops Using Multiple Processors
This paper describes a multibody dynamics algorithm formulated for parallel implementation on multiprocessor computing platforms using the divide-and-conquer approach. The system of interest is a general topology of rigid and elastic articulated bodies with or without loops. The algorithm divides the multibody system into a number of smaller sets of bodies in chain or tree structures, called "branches" at convenient joints called "connection points", and uses an Order-N (O (N)) approach to formulate the dynamics of each branch in terms of the unknown spatial connection forces. The equations of motion for the branches, leaving the connection forces as unknowns, are implemented in separate processors in parallel for computational efficiency, and the equations for all the unknown connection forces are synthesized and solved in one or several processors. The performances of two implementations of this divide-and-conquer algorithm in multiple processors are compared with an existing method implemented on a single processor
Anammox treatment performances using polyethylene sponge as a biomass carrier
Nitrogen removal using a polyethylene (PE) sponge biomass carrier was evaluated in a fixed-bed reactor for nitrogen removal by the anammox process. The fixed-bed reactor was operated continuously for 240 days. Average T-N removal efficiencies of each period increased from 38 % to 67 %, 72 %, 74 % to 75 % with stepwise increases in volumetric T-N loading rates. A T-N removal rate of 2.8 kg N/m3/day was obtained after 240 days of operation. After 3 months, anammox biomass fully covered the surface of the PE sponge carrier and the color of the material changed from white to red. Following 5 months of operation, biomass proliferated on the surface of the material and a dark-red color was observed. These results shown that anammox process using PE sponge materials as biomass carriers in the fixed-bed reactor will be suitable for NH4-N removal from wastewater containing high NH4-N. However, it is necessary to investigate whether PE sponge material can operate under high organic carbon concentrations in anammox process, because these wastewaters always contain high concentration of organic matter
Thermal conductivity enhancement of laser induced graphene foam upon P3HT infiltration
Significant research has been dedicated to the exploration of high thermal conductivity polymer composite materials with conductive filler particles for use in heat transfer applications. However, poor particle dispersibility and interfacial phonon scattering have limited the effective composite thermal conductivity. Three-dimensional foams with high ligament thermal conductivity offer a potential solution to the two aforementioned problems but are traditionally fabricated through expensive and/or complex manufacturing methods. Here, laser induced graphene foams, fabricated through a simple and cost effective laser ablation method, are infiltrated with poly(3-hexylthiophene) in a step-wise fashion to demonstrate the impact of polymer on the thermal conductivity of the composite system. Surprisingly, the addition of polymer results in a drastic (250%) improvement in material thermal conductivity, enhancing the graphene foam's thermal conductivity from 0.68 W/m-K to 1.72 W/m-K for the fully infiltrated composite material. Graphene foam density measurements and theoretical models are utilized to estimate the effective ribbon thermal conductivity as a function of polymer filling. Here, it is proposed that the polymer solution acts as a binding material, which draws graphene ligaments together through elastocapillary coalescence and bonds these ligaments upon drying, resulting in greatly reduced contact resistance within the foam and an effective thermal conductivity improvement greater than what would be expected from the addition of polymer alone
Changes in patient-reported satisfaction and quality-of-life 6 months after rhinoplasty
Background: Rhinoplasty is a challenging and demanding procedure in plastic surgery. Surgical success, patient satisfaction, and improved quality-of-life are important outcomes. Objectives: This study aimed to evaluate patient-reported satisfaction with appearance, treatment, and decision outcomes as well as quality-of-life after rhinoplasty using validated questionnaires. The role of patient demographics on outcomes was also studied. Methods: Patients who underwent a primary rhinoplasty were selected for this cohort study. Patient-reported satisfaction with appearance, treatment, and decision as well as quality-of-life were evaluated with the Utrecht Questionnaire and FACE-Q at intake and 6 months postoperatively. Results: Overall, 380 patients were included. Patients reported a more positive subjective perception of nasal appearance (VAS score) at 6 months post-surgery compared with preoperative scores (7.9 ± 1.6 vs 3.2 ± 1.4, p < 0.05). Furthermore, higher quality-of-life and body image scores were observed at 6 months postoperatively compared with preoperative scores (7.7 ± 3.5 vs 15.2 ± 4.4, p < 0.05). Patients reported high satisfaction with treatment outcome (70.3 ± 23.4) as well as with their decision to undergo surgery (75.9 ± 23.4) on a scale of 0–100 at 6 months postoperatively. Patients reached similar postoperative scores regardless of their intake scores. Patients ≥30 years and patients with a history of cosmetic surgery were less satisfied postoperatively. Conclusion: Despite differences in appearance satisfaction at intake, most patients showed greater satisfaction with appearance, treatment, and decision outcomes as well as quality-of-life 6 months postoperatively. However, older age and a history of cosmetic surgery influenced these outcomes negatively. These factors should be considered during preoperative management of outcome expectations.</p
New records for the liverwort and hornwort flora of Vietnam, 1
After the examination of the Cryptogam collection in the Herbarium of the University of Science, Vietnam National University Ho Chi Minh City (PHH), 25 species proved to be new to Vietnam, including one hornwort and 24 liverworts. Among them, four genera: Denotarisia Grolle, Gongylanthus Nees, Leiomitra Lindb. and Lepicolea Dumort. are new records for the country. Diagnostic characters and illustrations are given for some taxa, as well as locality notes and habitat descriptions are provided for each collecting area
Changes in patient-reported satisfaction and quality-of-life 6 months after rhinoplasty
Background: Rhinoplasty is a challenging and demanding procedure in plastic surgery. Surgical success, patient satisfaction, and improved quality-of-life are important outcomes. Objectives: This study aimed to evaluate patient-reported satisfaction with appearance, treatment, and decision outcomes as well as quality-of-life after rhinoplasty using validated questionnaires. The role of patient demographics on outcomes was also studied. Methods: Patients who underwent a primary rhinoplasty were selected for this cohort study. Patient-reported satisfaction with appearance, treatment, and decision as well as quality-of-life were evaluated with the Utrecht Questionnaire and FACE-Q at intake and 6 months postoperatively. Results: Overall, 380 patients were included. Patients reported a more positive subjective perception of nasal appearance (VAS score) at 6 months post-surgery compared with preoperative scores (7.9 ± 1.6 vs 3.2 ± 1.4, p < 0.05). Furthermore, higher quality-of-life and body image scores were observed at 6 months postoperatively compared with preoperative scores (7.7 ± 3.5 vs 15.2 ± 4.4, p < 0.05). Patients reported high satisfaction with treatment outcome (70.3 ± 23.4) as well as with their decision to undergo surgery (75.9 ± 23.4) on a scale of 0–100 at 6 months postoperatively. Patients reached similar postoperative scores regardless of their intake scores. Patients ≥30 years and patients with a history of cosmetic surgery were less satisfied postoperatively. Conclusion: Despite differences in appearance satisfaction at intake, most patients showed greater satisfaction with appearance, treatment, and decision outcomes as well as quality-of-life 6 months postoperatively. However, older age and a history of cosmetic surgery influenced these outcomes negatively. These factors should be considered during preoperative management of outcome expectations.</p
Reduced quasifission competition in fusion reactions forming neutron-rich heavy elements
Measurements of mass-angle distributions (MADs) for Cr + W reactions,
providing a wide range in the neutron-to-proton ratio of the compound system,
(N/Z)CN, have allowed for the dependence of quasifission on the (N/Z)CN to be
determined in a model-independent way. Previous experimental and theoretical
studies had produced conflicting conclusions. The experimental MADs reveal an
increase in contact time and mass evolution of the quasifission fragments with
increasing (N/Z)CN, which is indicative of an increase in the fusion
probability. The experimental results are in agreement with microscopic
time-dependent Hartree-Fock calculations of the quasifission process. The
experimental and theoretical results favor the use of the most neutron-rich
projectiles and targets for the production of heavy and superheavy nuclei.Comment: Accepted to PRC as a Rapid Communicatio
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