1,591 research outputs found
Rates of Sediment Accumulation, Bioturbation and Resuspension in Back Bay, Virginia, a Coastal Lagoon
Back Bay is the northernmost section of the Albemarle-Pamlico lagoon-estuary system. Back Bay lagoon and its associated barrier (Currituck Spit) are moving landward in response to post-glacial sea level rise (2.6 mm yr-1). The long term (100 year time scale) landward migration rate of Currituck Spit may be on the order of a meter per year.
Sediment accumulation, resuspension and bioturbation are processes in Back Bay that control the residence time of organic matter in the bay floor. and therefore, effect the rate of nutrient release. As burial proceeds, nutrients in the zone of mixing may be remineralized and recycled back to to water column, or may pass downwards into the zone of permanent burial.
X-radiographs indicate that Back Bay sediments are bioturbated by the community of insect larvae, polychaetes and oligochaetes that constitute the benthic infauna of this oligohaline water body. However, analysis of wind records suggests that in some respects, wave resuspension is a more important mixing process. Under mild to moderate conditions, waves in the bay are fetch limited. However, under hurricane conditions the bay surface saturates with breaking waves before peak winds are attained. For a 6 km fetch (a typical long fetch for the Bay), the resuspension threshold is 6 ms-1 (13.5 knots). This value is exceeded 35.7 percent of the time, and sediment is resuspended in about 40 events in a year. Radiogeochemical analyses suggest that long term (100 yr) accumulation rates are of the order of 2-3 mm yr-1.
The Bay is floored by mud (silt and clay), with an admixture of sand. Sediment introduction probably occurs largely as a result of \u27wind pumping\u27. During winter storms, strong southerly winds set down southern Back Bay, and drive turbid water from Currituck Sound through the Knotts Island Passage. As the storm progresses, the wind shifts to the north and northwest, sets up lower Back Bay against the Knotts Island Passage, and flushes sediment and water back into Currituck Sound.
In this model, Back Bay is a sediment-accumulating sink. The shallow (1-2 m) floor of Back Bay is controlled by an equilibrium between the rate of sediment supply and mean annual wave power. Concentration profiles of 210Pb and 137Cs measured in 1984 indicate that the short term (30 year) accumulation rate was then twice that of sea level rise. The period of record corresponds with Eurasian Milfoil invasion. The historically dense growth of this plant would have modified the equilibrium by damping wave currents, accelerating the sedimentation rate and shifting the Bay floor to a shallower equilibrium depth. The Bay floor appears to presently be undergoing a reduced rate of sedimentation with some local erosion, perhaps in conjunction with a return to an earlier regime
Generation, characterization and application of atmospheric pressure plasma jet
The development of a non-thermal plasma jet with a capillary configuration working at atmospheric pressure is reported in this paper. The plasma jet is powered by a power source with frequency of several kilohertz. The working gas is argon. The plasma obtained has been characterized by optical emission spectroscopic measurements and electrical measurements of the discharge using voltage and current probes. The electron temperature has been estimated by using the modified Boltzmann plot method utilizing the Ar 4p-4s transition. The electron temperatures at various positions along the plasma jet length have been obtained and it is found that the electron temperature decreases at position further from orifice. The electron density has been estimated from current and voltage measurements using the power balance method. The effects of gas flow rate, applied voltage and frequency on the characteristics of the plasma jet have also been investigated. The applications of the atmospheric pressure plasma jet (APPJ) developed to modify the surface properties of Polyethyleneterephthalate (PET) and polycarbonate (PC) have been tested. Our results showed that the atmospheric pressure non-thermal plasma jet can be effectively used to enhance the surface wettability and surface energy of the PET and PC. The plasma jet has also been tested for inactivation of prokaryotic cells (Escherichia coli, Staphylococcus aureus). In the case of E. coli, better than 4 log10 reduction can be achieved. The effect of plasma jet on the pH of cell culture medium has suggested that the plasma species, particularly the electrons, are solely responsible for the effect of inactivation of living cells
Long-term follow-up of intratympanic methylprednisolone versus gentamicin in patients with unilateral Menière’s disease
Objectives: To determine whether long term (>48 months)
symptomatic vertigo control is sustained in patients with
Menie`re’s disease from a previous comparative trial of
intratympanic methylprednisolone versus gentamicin, and if the two treatments remain nonsignificantly different at longterm follow-up.
Study Design: Mail survey recording vertigo frequency in
the previous one and six months, further intratympanic
treatment received, and validated symptom questionnaires.
Setting: Outpatient hospital clinic setting.
Patients: Adult patients with definite unilateral refractory Menie`re’s disease, who previously received in tratympanic treatment in a comparative trial.
Intervention: A survey of trial participants who received
intratympanic gentamicin (40 mg/mL) or methylprednisolone
(62.5 mg/mL).
Outcome measures: Primary: number of vertigo attacks in
the 6 months prior to receiving this survey compared with
the 6 months before the first trial injection.
Secondary: : Number of vertigo attacks over the previous 1 month; validated symptom questionnaire scores of tinnitus, dizziness, vertigo, aural fullness, and functional disability.
Results: Average follow-up was 70.8 months (standard
deviation 17.0) from the first treatment injection. Vertigo attacks in the 6 months prior to receiving the current survey reduced by 95% compared to baseline in both drug groups (intention-to-treat analysis, both p<0.001). No significant difference between drugs was found for the primary and secondary outcomes. Eight participants (methylprednisolone ¼ 5 and gentamicin ¼ 3) required further injections for relapse after completing the original trial.
Conclusion: Intratympanic methylprednisolone treatment provides effective long-lasting relief of vertigo, without the known inner-ear toxicity associated with gentamicin. There are no significant differences between the two treatments at long term follow-up
La ideología de género: una respuesta de la Antropología y la Teología
El trabajo analiza la historia y desarrollo de los movimientos feministas, así como las repercusiones de la IV Conferencia Mundial de la Mujer (Pekín, 1995) que, según muchos estudiosos, ha sido utilizada como una importante plataforma para el desarrollo del feminismo radical, cuyo objetivo es eliminar o no dar relieve particular a la bipolaridad sexual del ser humano. Primero se ponen de manifiesto las consecuencias que estas corrientes comportan para el ser humano, el matrimonio, la familia, etc., y después se considera la respuesta al feminismo radical desde la antropología y la teología.
El estudio pone de relieve cómo la realidad diferenciada de ser varón y ser mujer pertenece a la persona humana como tal y, por eso mismo, respetar esa diferenciación es irrenunciable en la valoración adecuada de la verdadera dignidad del varón y de la mujer. La consideración de la sexualidad como dimensión constitutiva de la persona, su ordenación al don y a la complementariedad, y el respeto de su estructura, son algunos de estos significados.
Además de responder a los argumentos de carácter antropológico en los que se intenta apoyar el feminismo radical, la investigación busca recuperar las nociones antropológicas claves que son necesarias para desmontar los postulados principales de estas corrientes.This work analyzes the history and development of feminist movements, as well as the repercussions of the IV World Conference on Women (Beijing, 1995). According to many scholars, this Conference has been used as an important platform for the development of radical feminism, whose objective is to eliminate or make irrelevant the sexual bipolarity of human beings. First the consequences of these ideologies for individuals, married couples, and families are analyzed. Then the response to radical feminism from anthropology and theology is considered.
The study highlights how the differentiated reality of being male and being female belongs to the human person as such. For this reason, respecting this differentiation is essential in the correct assessment of the true dignity of men and women. The consideration of sexuality as a constitutive dimension of the person, its orientation towards self-giving and complementarity, and the respect for its structure are some of these meanings.
Apart from responding to the anthropological arguments on which radical feminism bases its ideas, the research seeks to recover the key anthropological notions which are necessary to rebut the main postulates of these movements
Effects of Pore Walls and Randomness on Phase Transitions in Porous Media
We study spin models within the mean field approximation to elucidate the
topology of the phase diagrams of systems modeling the liquid-vapor transition
and the separation of He--He mixtures in periodic porous media. These
topologies are found to be identical to those of the corresponding random field
and random anisotropy spin systems with a bimodal distribution of the
randomness. Our results suggest that the presence of walls (periodic or
otherwise) are a key factor determining the nature of the phase diagram in
porous media.Comment: REVTeX, 11 eps figures, to appear in Phys. Rev.
Nuclear shell-model calculations for 6Li and 14N with different NN potentials
Two ``phase-shift equivalent'' local NN potentials with different
parametrizations, Reid93 and NijmII, which were found to give nearly identical
results for the triton by Friar et al, are shown to yield remarkably similar
results for 6Li and 14N in a (0+2)hw no-core space shell-model calculation. The
results are compared with those for the widely used Hamada-Johnson hard-core
and the original Reid soft-core potentials, which have larger deuteron D-state
percentages. The strong correlation between the tensor strength and the nuclear
binding energy is confirmed. However, many nuclear-structure properties seem to
be rather insensitive to the details of the NN potential and, therefore, cannot
be used to test various NN potentials. (Submitted to Phys. Rev. C on Nov. 9,
1993 as a Brief Report.)Comment: 12 text pages and 1 figure (Figure available upon request),
University of Arizona Physics Preprint (Number not yet assigned
Characterizing Radiation‐Belt Energetic Electron Precipitation Spectra: A Comparison of Quasi‐Linear Diffusion Theory With In Situ Measurements
High energy electron precipitation from the Earth's radiation belts is important for loss from the radiation belts and atmospheric chemistry. We follow up investigations presented in Reidy et al. (2021, https://doi.org/10.1029/2020ja028410) where precipitating flux is calculated inside the field of view of the POES T0 detector using quasi-linear theory and pitch angle diffusion coefficients (Dαα) from the British Antarctic Survey (BAS). These results showed good agreements at >30 keV for L* >5 on the dawnside but the flux were too low at higher energies. We have investigated the effect of changing parameters in the calculation of the precipitating flux to improve the results for the higher energies using comparisons of in situ flux and cold plasma measurements from GOES-15 and RBSP. We find that the strength of the diffusion coefficients rather than the shape of the source spectrum has the biggest effect on the calculated precipitation. In particular we find decreasing the cold plasma density used in the calculation of Dαα increases the diffusion and hence the precipitation at the loss cone for the higher energies, improving our results. The method of calculating Dαα is also examined, comparing co-located rather than averaged RBSP measurements. We find that the method itself has minimal effect but using RBSP derived Dαα improved our results over using Dαα calculated using the entire BAS wave data base; this is potentially due to better measurements of the cold plasma density from RBSP than the other spacecraft included in the BAS wave data base (e.g., THEMIS)
Allowed Gamow-Teller Excitations from the Ground State of 14N
Motivated by the proposed experiment , we study the
final states which can be reached via the allowed Gamow-Teller mechanism. Much
emphasis has been given in the past to the fact that the transition matrix
element from the ground state of to the ground state of is very close to zero, despite the fact that all
the quantum numbers are right for an allowed transition. We discuss this
problem, but, in particular, focus on the excitations to final states with
angular momenta and . We note that the summed strength to the
states, calculated with a wide variety of interactions, is
significantly larger than that to the final states.Comment: Submitted to Phys. Rev.
Scale-free static and dynamical correlations in melts of monodisperse and Flory-distributed homopolymers: A review of recent bond-fluctuation model studies
It has been assumed until very recently that all long-range correlations are
screened in three-dimensional melts of linear homopolymers on distances beyond
the correlation length characterizing the decay of the density
fluctuations. Summarizing simulation results obtained by means of a variant of
the bond-fluctuation model with finite monomer excluded volume interactions and
topology violating local and global Monte Carlo moves, we show that due to an
interplay of the chain connectivity and the incompressibility constraint, both
static and dynamical correlations arise on distances . These
correlations are scale-free and, surprisingly, do not depend explicitly on the
compressibility of the solution. Both monodisperse and (essentially)
Flory-distributed equilibrium polymers are considered.Comment: 60 pages, 49 figure
J/Psi suppression in colliding nuclei: statistical model analysis
We consider the suppression at a high energy heavy ion collision. An
ideal gas of massive hadrons in thermal and chemical equilibrium is formed in
the central region. The finite-size gas expands longitudinally in accordance
with Bjorken law. The transverse expansion in a form of the rarefaction wave is
taken into account. We show that suppression in such an environment,
when combined with the disintegration in nuclear matter, gives correct
evaluation of NA38 and NA50 data in a broad range of initial energy densities.Comment: 14 pages, 13 figures. Accepted for publication in Phys. Rev.
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