990 research outputs found
Material Dependence of the Wire-Particle Casimir Interaction
We study the Casimir interaction between a metallic cylindrical wire and a
metallic spherical particle by employing the scattering formalism. At large
separations, we derive the asymptotic form of the interaction. In addition, we
find the interaction between a metallic wire and an isotropic atom, both in the
non-retarded and retarded limits. We identify the conditions under which the
asymptotic Casimir interaction does not depend on the material properties of
the metallic wire and the particle. Moreover, we compute the exact Casimir
interaction between the particle and the wire numerically. We show that there
is a complete agreement between the numerics and the asymptotic energies at
large separations. For short separations, our numerical results show good
agreement with the proximity force approximation
Apex Exponents for Polymer--Probe Interactions
We consider self-avoiding polymers attached to the tip of an impenetrable
probe. The scaling exponents and , characterizing the
number of configurations for the attachment of the polymer by one end, or at
its midpoint, vary continuously with the tip's angle. These apex exponents are
calculated analytically by -expansion, and numerically by simulations
in three dimensions. We find that when the polymer can move through the
attachment point, it typically slides to one end; the apex exponents quantify
the entropic barrier to threading the eye of the probe
Fluctuation-induced forces between inclusions in a fluid membrane under tension
We discuss the fluctuation-induced force, a finite-temperature analog of the
Casimir force, between two inclusions embedded in a fluid membrane under
tension. We suggest a method to calculate this Casimir interaction in the most
general case, where membrane fluctuations are governed by the combined action
of surface tension, bending modulus, and the Gaussian rigidity. We find that
the surface tension strongly modifies the power law in the separation
dependence of the Casimir interaction. This results in a strong suppression of
the Casimir force at separations beyond a characteristic length, which could
affect protein aggregation dynamics in cell membranes.Comment: 4 pages, 1 figur
Life cycle information from a Wisconsin poplation of Porcellio spinicoris, the dark-headed isopod
Detailed life cycle information is lacking for Wisconsin terrestrial isopod crustaceans. We measured head-widths of a local population of Porcellio spinicornis and compiled data on size frequencies, sex ratio and gravidity. Females were larger and formed a majority of the population. Gravidity showed a definite seasonal pattern; percentages of gravid females ranged from zero in March and April to near 80% in late May and early June
Evaluation of drought tolerance indices among some winter rapeseed cultivars
The main purpose of this study was to evaluate the effect of drought stress on seed yield of some winter rapeseed cultivars and to study relevant drought tolerance indices, along with identifying resistant cultivars to drought stress. Plant materials were sown in split plot arrangement based on a randomized complete blocks design, at Islamic Azad University of Tabriz research field. Three drought stress levels which include 80, 130, and 180 mm water evaporation from class A pan were considered as the main factor levels, while seven winter rapeseed cultivars which include Licord, Okapi, Opera, S.L.M.046, Zarfam, Modena, and Talaye were arranged to sub plots. Studied quantitative drought tolerance indices were, tolerance index (TOL), mean productivity (MP), stress susceptibility index (SSI), stress tolerance index (STI), geometric mean productivity (GMP), yield index (YI), yield stability index (YSI), and percentage of yield reduction (%Reduction). The yield stability analysis of the studied cultivars was done by GGE biplot method. According to the results derived from principal component analysis and regarding evaluation of correlation coefficients among indices, STI and GMP were selected as the two superior indices for identifying drought resistant cultivars. Three dimensional scatter plots based on STI and GMP indices showed that Licord and Talaye were the most suitable cultivars, and were situated in group, A. In addition, Modena and Zarfam were identified as sensitive and resistant to drought stress, respectively.Key words: Brassica napus L, principal component analysis, drought stress, drought tolerance indices, stability analysis (GGE biplot), 3D scatter plot
Elastic Lattice Polymers
We study a model of "elastic" lattice polymer in which a fixed number of
monomers is hosted by a self-avoiding walk with fluctuating length . We
show that the stored length density scales asymptotically
for large as , where is the
polymer entropic exponent, so that can be determined from the analysis
of . We perform simulations for elastic lattice polymer loops with
various sizes and knots, in which we measure . The resulting estimates
support the hypothesis that the exponent is determined only by the
number of prime knots and not by their type. However, if knots are present, we
observe strong corrections to scaling, which help to understand how an entropic
competition between knots is affected by the finite length of the chain.Comment: 10 page
Modular sensor nodes for environmental data monitoring
A framework for modular wireless sensor networks (WSN) designed to capture and monitor micro-climates in a crop field. WSN is rapidly improving in automotive industry, agricultural, industrial and environmental monitoring and many other areas. Moulder architecture minimises the software upgrade down time and enables hardware reusability. Recent developments and advances in wireless technology as well as affordability give rise to this emerging field in the realm of Precision Agriculture (PA). Vineyard monitoring is an emerging application field in PA
Evaluation of in vitro antiviral activity of a brown alga (Cystoseira myrica) from the Persian Gulf against herpes simplex virus type 1
The hot water extract of a brown marine alga, Cystoseira myrica, from the Persian Gulf was evaluated as an antiviral compound against KOS strain of HSV-1 in cell culture. The extract exhibited antiviralactivity against herpes simplex virus type 1 (HSV-1) not only during absorption of virus to the cells, but also on post attachment stages of virus replication. The water extract of C. myrica was sterilized byfiltration and autoclaving, respectively. The IC50 for filtered extract was 99 ìg/ml and the IC50 for autoclaved extract was 125 ìg/ml. Based on resulted selectivity index (SI) values of the extracts, whichwere 33.4 and 28.2 for filtered and autoclaved extracts, respectively, we found that the antiviral compound(s) in the water extract of C. myrica to be heat stable. Also, the SI values for inhibition of thepost attachment stages of HSV-1 replication were 23.1 and 21.7 for filtered and autoclaved extracts, respectively. The IC50 in this phase of study were 143 and 162 ìg/ml for filtered and autoclaved extracts,respectively. Therefore, C. myrica could be a good candidate as a natural source for anti-HSV-1 compound(s) isolation
Thinning of superfluid films below the critical point
Experiments on He films reveal an attractive Casimir-like force at the
bulk -point, and in the superfluid regime. Previous work has explained
the magnitude of this force at the transition and deep in the
superfluid region but not the substantial attractive force immediately below
the -point. Utilizing a simple mean-field calculation renormalized by
critical fluctuations we obtain an effective Casimir force that is
qualitatively consistent with the scaling function obtained by
collapse of experimental data.Comment: 4 page
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