4,527 research outputs found
An integral equation approach to the plasma self consistent field problem
Problem of collisionless, fully ionized single component plasma treated by means of Green functio
Methods of Quadrature for Euler Transform Integrals
Quadrature methods for Euler transform integral
Marine fish calendar.12. Mandapam
The Ramanathapuram District with a coastline of
261 km, covering the sea-front of Gulf of Mannar and
Palk Bay, ranks foremost in marine fish production of
Tamil Nadu State. Sustaining high levels of organic
production, the seas along the coast have lucrative fishing
grounds with greater profusion of finfishes, shellfishes,
seaweeds and other economically important organisms
Tunable-porosity membranes from discrete nanoparticles
Thin film composite membranes were prepared through a facile single-step wire-wound rod coating procedure in which internally crosslinked poly(styrene-co-butadiene) polymer nanoparticles self-assembled to form a thin film on a hydrophilic ultrafiltration support. This nanoparticle film provided a defect-free separation layer 130–150 nm thick, which was highly permeable and able to withstand aggressive pH conditions beyond the range of available commercial membranes. The nanoparticles were found to coalesce to form a rubbery film when heated above their glass transition temperature (T(g)). The retention properties of the novel membrane were strongly affected by charge repulsion, due to the negative charge of the hydroxyl functionalized nanoparticles. Porosity was tuned by annealing the membranes at different temperatures, below and above the nanoparticle T(g). This enabled fabrication of membranes with varying performance. Nanofiltration properties were achieved with a molecular weight cut-off below 500 g mol(−1) and a low fouling tendency. Interestingly, after annealing above T(g), memory of the interstitial spaces between the nanoparticles persisted. This memory led to significant water permeance, in marked contrast to the almost impermeable films cast from a solution of the same polymer
The photospheric solar oxygen project: III. Investigation of the centre-to-limb variation of the 630nm [OI]-NiI blend
The solar photospheric abundance of oxygen is still a matter of debate. For
about ten years some determinations have favoured a low oxygen abundance which
is at variance with the value inferred by helioseismology. Among the oxygen
abundance indicators, the forbidden line at 630nm has often been considered the
most reliable even though it is blended with a NiI line. In Papers I and Paper
II of this series we reported a discrepancy in the oxygen abundance derived
from the 630nm and the subordinate [OI] line at 636nm in dwarf stars, including
the Sun. Here we analyse several, in part new, solar observations of the the
centre-to-limb variation of the spectral region including the blend at 630nm in
order to separate the individual contributions of oxygen and nickel. We analyse
intensity spectra observed at different limb angles in comparison with line
formation computations performed on a CO5BOLD 3D hydrodynamical simulation of
the solar atmosphere. The oxygen abundances obtained from the forbidden line at
different limb angles are inconsistent if the commonly adopted nickel abundance
of 6.25 is assumed in our local thermodynamic equilibrium computations. With a
slightly lower nickel abundance, A(Ni)~6.1, we obtain consistent fits
indicating an oxygen abundance of A(O)=8.73+/-0.05. At this value the
discrepancy with the subordinate oxygen line remains. The derived value of the
oxygen abundance supports the notion of a rather low oxygen abundance in the
solar hotosphere. However, it is disconcerting that the forbidden oxygen lines
at 630 and 636nm give noticeably different results, and that the nickel
abundance derived here from the 630nm blend is lower than expected from other
nickel lines.Comment: to appear in A&
Improved simulation of aerosol, cloud, and density measurements by shuttle lidar
Data retrievals are simulated for a Nd:YAG lidar suitable for early flight on the space shuttle. Maximum assumed vertical and horizontal resolutions are 0.1 and 100 km, respectively, in the boundary layer, increasing to 2 and 2000 km in the mesosphere. Aerosol and cloud retrievals are simulated using 1.06 and 0.53 microns wavelengths independently. Error sources include signal measurement, conventional density information, atmospheric transmission, and lidar calibration. By day, tenuous clouds and Saharan and boundary layer aerosols are retrieved at both wavelengths. By night, these constituents are retrieved, plus upper tropospheric, stratospheric, and mesospheric aerosols and noctilucent clouds. Density, temperature, and improved aerosol and cloud retrievals are simulated by combining signals at 0.35, 1.06, and 0.53 microns. Particlate contamination limits the technique to the cloud free upper troposphere and above. Error bars automatically show effect of this contamination, as well as errors in absolute density nonmalization, reference temperature or pressure, and the sources listed above. For nonvolcanic conditions, relative density profiles have rms errors of 0.54 to 2% in the upper troposphere and stratosphere. Temperature profiles have rms errors of 1.2 to 2.5 K and can define the tropopause to 0.5 km and higher wave structures to 1 or 2 km
The photospheric solar oxygen project: IV. 3D-NLTE investigation of the 777 nm triplet lines
The solar photospheric oxygen abundance is still widely debated. Adopting the
solar chemical composition based on the "low" oxygen abundance, as determined
with the use of three-dimensional (3D) hydrodynamical model atmospheres,
results in a well-known mismatch between theoretical solar models and
helioseismic measurements that is so far unresolved. We carry out an
independent redetermination of the solar oxygen abundance by investigating the
center-to-limb variation of the OI IR triplet lines at 777 nm in different sets
of spectra with the help of detailed synthetic line profiles based on 3D
hydrodynamical CO5BOLD model atmospheres and 3D non-LTE line formation
calculations with NLTETD. The idea is to simultaneously derive the oxygen
abundance,A(O), and the scaling factor SH that describes the cross-sections for
inelastic collisions with neutral hydrogen relative the classical Drawin
formula. The best fit of the center-to-limb variation of the triplet lines
achieved with the CO5BOLD 3D solar model is clearly of superior quality
compared to the line profile fits obtained with standard 1D model atmospheres.
Our best estimate of the 3D non-LTE solar oxygen abundance is A(O) = 8.76 +/-
0.02, with the scaling factor SH in the range between 1.2 and 1.8. All 1D
non-LTE models give much lower oxygen abundances, by up to -0.15 dex. This is
mainly a consequence of the assumption of a -independent microturbulence.Comment: 25 pages, 17 figures, 7 tables (Accepted for publication in A&A
Roll-to-roll dip coating of three different PIMs for Organic Solvent Nanofiltration
PIM-1, PIM-7, and PIM-8 composite membranes have been fabricated for Organic Solvent Nanofiltration (OSN) on two different support membranes. Both support membranes, PAN and crosslinked Ultem 1000, displayed pore sizes within the range of 20–25 nm as characterised by gas liquid porometry. PIM layers of < 500 nm thickness were formed from dip coating on a roll-to-roll pilot line. The resultant composite membranes exhibited typical MWCOs in the region of 500–800 g mol−1. The quality of coating obtained on the crosslinked Ultem 1000 support membrane was consistently higher for all three PIMs than that obtained on the PAN membrane. The PIM composite membranes coated on to crosslinked Ultem 1000 were stable in a wider range of solvents than those on the PAN support. OSN testing in a model system with isomeric alkane solutes verified that manipulated changes to the molecular architecture of the polymer backbone resulted in a higher separation factor between straight and branched alkane isomers
Equilibrium topology of the intermediate state in type-I superconductors of different shapes
High-resolution magneto-optical technique was used to analyze flux patterns
in the intermediate state of bulk Pb samples of various shapes - cones,
hemispheres and discs. Combined with the measurements of macroscopic
magnetization these results allowed studying the effect of bulk pinning and
geometric barrier on the equilibrium structure of the intermediate state.
Zero-bulk pinning discs and slabs show hysteretic behavior due to geometric
barrier that results in a topological hysteresis -- flux tubes on penetration
and lamellae on flux exit. (Hemi)spheres and cones do not have geometric
barrier and show no hysteresis with flux tubes dominating the intermediate
field region. It is concluded that flux tubes represent the equilibrium
topology of the intermediate state in reversible samples, whereas laminar
structure appears in samples with magnetic hysteresis (either bulk or
geometric). Real-time video is available in
http://www.cmpgroup.ameslab.gov/supermaglab/video/Pb.html
NOTE: the submitted images were severely downsampled due to Arxiv's
limitations of 1 Mb total size
Effectiveness of START psychological intervention in reducing abuse by dementia family carers: randomized controlled trial
BACKGROUND: Family carers of people with dementia frequently report acting abusively toward them and carer psychological morbidity predicts this. We investigated whether START (STrAtegies for RelaTives), a psychological intervention which reduces depression and anxiety in family carers also reduces abusive behavior in carers of people living in their own homes. We also explored the longitudinal course of carer abusive behavior over two year. METHODS: We included self-identified family carers who gave support at least weekly to people with dementia referred in the previous year to three UK mental health services and a neurological dementia service. We randomly assigned these carers to START, an eight-session, manual-based coping intervention, or treatment as usual (TAU). Carer abusive behavior (Modified Conflict Tactic Scale (MCTS) score ≥2 representing significant abuse) was assessed at baseline, 4, 8, 12, and 24 months. RESULTS: We recruited 260 carers, 173 to START and 87 to TAU. There was no evidence that abusive behavior levels differed between randomization groups or changed over time. A quarter of carers still reported significant abuse after two years, but those not acting abusively at baseline did not become abusive. CONCLUSION: There was no evidence that START, which reduced carer anxiety and depression, reduced carer abusive behavior. For ethical reasons, we frequently intervened to manage concerning abuse reported in both groups, which may have disguised an intervention effect. Future dementia research should include elder abuse as an outcome, and consider carefully how to manage detected abuse
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