10,949 research outputs found
The Cosmic Microwave Background Spectrum and a Determination of Fractal Space Dimensionality
The possibility to constrain fractal space dimensionality from Astrophysics
and other areas is briefly reviewed. Assuming such dimensionality to be , a limit to can be inferred from COBE satellite data. The
available data for the cosmic microwave background radiation spectrum are
fitted by a Planck's radiation distribution generalized to non integer space
dimensionality. Our analysis shows that the shape of the CMBR spectrum, which
does not depend on the absolute normalization, is correctly described from this
distribution provided the absolute temperature is equal to 2.726
K and .
This value for is shown to be consistent with what is found on a
very different spatial scale based on a quantum field phenomenon. The
is interpreted as an upper limit for how much space dimensionality
could have deviated from three. In other words, this is the maximum fluctuation
space dimensionality should have experienced in a spatial and temporal scale
compared to that of the decoupling era.Comment: 6 pages, 2 figure
Comparison of LPS-stimulated release of cytokines in punch versus transwell tissue culture systems of human gestational membranes
Abstract Background Cytokine signaling within the amnionic, chorionic and decidual extraplacental gestational membranes plays an important role in membrane rupture and the timing of birth. The predominant in vitro explant culture system for evaluating cytokine induction in human gestational membranes has been the free-floating biopsy punch culture. Punch systems have been used to investigate the impact of various toxicants, pharmaceuticals and genetic variation on expression of pro-inflammatory cytokines. More recently, a dual compartment transwell culture system has been developed that more closely mimics the intrauterine compartment. The current study compares these two systems with respect to release of pro- and anti-inflammatory cytokines in response to lipopolysaccharide (LPS), a model stimulant. Methods Tissue samples were exposed to 100 ng/ml LPS for 12 h and cytokines were measured by ELISA. Data are expressed as increase relative to non-treated controls. Results Levels of interleukin-6 increased in punch culture medium samples to a significantly greater extent (34.2 fold) compared with medium from transwell cultures in the amnion (6.6 fold) or choriodecidual (7.1 fold) compartments. Interleukin-8 also showed a significantly greater induction in punch (4.8 fold) than transwell amnion (1.6 fold) or choriodecidual (1.7 fold) samples. The anti-inflammatory interleukin-10 showed a significant difference between punch (36.5 fold) and transwell amnion (15.4 fold) samples, but no difference was observed between punch and transwell choriodecidual (28.5 fold) samples. Neither interleukin-1beta nor tumor necrosis factor-alpha (TNF-alpha) showed a significant difference between the punch and transwell samples. Conclusions These results indicate that the pattern of LPS-stimulated cytokine release from gestational membranes in vitro depends on the culture system used, confounding comparisons of studies that use different gestational membrane culture systems to study inflammatory responses.http://deepblue.lib.umich.edu/bitstream/2027.42/78253/1/1477-7827-8-121.xmlhttp://deepblue.lib.umich.edu/bitstream/2027.42/78253/2/1477-7827-8-121.pdfPeer Reviewe
Off-diagonal helicity density matrix elements for vector mesons produced in polarized e+e- processes
Final state quark-antiquark interactions give origin to non zero values of
the off-diagonal element rho_{1,-1} of the helicity density matrix of vector
mesons produced in e+e- annihilations, as confirmed by recent OPAL data on Phi,
D^* and K^*'s. New predictions are given for rho_{1,-1} of several mesons
produced at large x_E and small p_T -- i.e. collinear with the parent jet -- in
the annihilation of polarized e+ and e-; the results depend strongly on the
elementary dynamics and allow further non trivial tests of the Standard Model.Comment: LaTeX, 20 pages, 6 ps figures, uses epsfig.st
Giant enhanced optical nonlinearity of colloidal nanocrystals with a graded-index host
The effective linear and third-order nonlinear optical properties of metallic
colloidal crystal immersed in a graded-index host fluid are investigated
theoretically. The local electric fields are extracted self-consistently based
on the layer-to-layer interactions, which are readily given by the Lekner
summation method. The resultant optical absorption and nonlinearity enhancement
show a series of sharp peaks, which merge in a broadened resonant band. The
sharp peaks become a continuous band for increasing packing density and number
of layers. We believe that the sharp peaks arise from the in-plane dipolar
interactions and the surface plasmon resonance, whereas the continuous band is
due to the presence of the gradient in the host refractive index. These results
have not been observed in homogeneous and randomly-dispersed colloids, and thus
would be of great interest in optical nanomaterial engineering.Comment: Submitted to Applied Physics Letter
Noise-enhanced classical and quantum capacities in communication networks
The unavoidable presence of noise is thought to be one of the major problems
to solve in order to pave the way for implementing quantum information
technologies in realistic physical platforms. However, here we show a clear
example in which noise, in terms of dephasing, may enhance the capability of
transmitting not only classical but also quantum information, encoded in
quantum systems, through communication networks. In particular, we find
analytically and numerically the quantum and classical capacities for a large
family of quantum channels and show that these information transmission rates
can be strongly enhanced by introducing dephasing noise in the complex network
dynamics.Comment: 4 pages, 4 figures; See Video Abstract at
http://www.quantiki.org/video_abstracts/1003587
Quark fragmentation into vector and pseudoscalar mesons at LEP
Some data on the ratio of vector to vector + pseudoscalar mesons, V/(V+P),
and the probability of helicity zero vector states, rho_00, are now available
from LEP. A possible relation between these two quantities and their
interpretation in terms of polarized fragmentation functions are discussed;
numerical estimates are given for the relative occupancies of K and K*, D and
D*, B and B* states.Comment: 5 pages, no figure
Toward the valorization of olive (Olea europaea var. europaea L.) biodiversity: horticultural performance of seven Sicilian cultivars in a hedgerow planting system
An intense survey of the Sicilian's olive growing areas for autochthonous germplasm, mainly represented by centennials olive trees (Olea europaea var. europaea L.) apparently older then III centuries, started at the beginning of the 1980s and resulted in the selection of more than 150 cultivars and accessions. This germplasm was propagated in a nursery, by grafting onto seedlings of Olea europaea L., and planted in an experimental orchard, in an olive district located in the South-west of the Island, where they were evaluated for over 30 years and selected for their early bearing, high and constant productivity, as well as high oil content of the fruits and excellent chemical (oleic acid and phenol content) and organoleptic profile of the oil. This paper reports data on the horticultural performances (production, vigor, crop efficiency and oil quality) of four cultivars (\u2018Kalat\u2019, \u2018Olivo di Mandanici\u2019, \u2018Abunara\u2019 and \u2018Minuta\u2019), selected within the Sicilian's autochthonous germplasm trained as 'Free Palmetta' and tested in a hedgerow planting system at three different planting densities: 500, 666 and 1000 trees ha-1. The cultivar \u2018Nocellara del Belice\u2019, \u2018Cerasuola, and \u2018Biancolilla\u2019, widely cultivated in the area where the trial was carried out, were used as references. The outstanding performance of the cultivar \u2018Kalat\u2019 at planting density of 1000 trees ha 121, suggests that this cultivar can be a promising choice for the super high density orchards (SHD). The other cultivars tested did not performed as \u2018Kalat\u2019 and seem not suitable for SHD planting system due to their high vigor. The hedgerow planting system tested, in the first 6 years of planting, increaseed productivity of all cultivars compared to traditional olive orchard typical of the area where the trial was conducted. This hedgerow olive orchard may represent a valid solution to increase orchard productivity and to reduce harvest costs by mechanization, depending on tree high, with straddle or side by side canopy contact machines. Achieve higher yield and reducing management costs using autochthonous, resilient cultivars, could be a new strategy to counteract climate changes. The unique organoleptic profiles of the oils obtained from the cultivars tested, could improve the offer of tasty, flavored and nutraceutical extra virgin olive oils in the international markets. Results highlight the importance of preserving and valorizing biodiversity to increase productivity and resiliency of agricultural systems, facing continuous, fast and deep social and environmental changes
Effects on the Non-Relativistic Dynamics of a Charged Particle Interacting with a Chern-Simons Potential
The hydrogen atom in two dimensions, described by a Schr\"odinger equation
with a Chern-Simons potential, is numerically solved. Both its wave functions
and eigenvalues were determined for small values of the principal quantum
number . The only possible states correspond to . How the result
depends on the topological mass of the photon is also discussed. In the case
, the energy of the fundamental state corresponding to different choice
for the photon mass scale are found to be comprehended in the interval , corresponding to a mean
radius of the electron in the range ~cm
~cm. In any case, the planar
atom is found to be very weekly bounded showing some features similar to the
Rydberg atoms in three dimensions with a Coulombian interaction.Comment: 6 pages, 5 figure
Pool temperature stratification analysis in CIRCE-ICE facility with RELAP5-3D© model and comparison with experimental tests
In the frame of heavy liquid metal (HLM) technology development, CIRCE pool facility at ENEA/Brasimone Research Center was updated by installing ICE (Integral Circulation Experiments) test section which simulates the thermal behavior of a primary system in a HLM cooled pool reactor. The experimental campaign led to the characterization of mixed convection and thermal stratification in a HLM pool in safety relevant conditions and to the distribution of experimental data for the validation of CFD and system codes. For this purpose, several thermocouples were installed into the pool using 4 vertical supports in different circumferential position for a total of 119 thermocouples [1][2]. The aim of this work is to investigate the capability of the system code RELAP5-3D (c) to simulate mixed convection and thermal stratification phenomena in a HLM pool in steady state conditions by comparing code results with experimental data. The pool has been simulated by a 3D component divided into 1728 volumes, 119 of which are centered in the exact position of the thermocouples. Three dimensional model of the pool is completed with a mono-dimensional nodalization of the primary main flow path. The results obtained by code simulations are compared with a steady state condition carried out in the experimental campaign. Results of axial, radial and azimuthal temperature profile into the pool are in agreement with the available experimental data Furthermore the code is able to well simulate operating conditions into the main flow path of the test section
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