15,554 research outputs found
Reliable routing scheme for indoor sensor networks
Indoor Wireless sensor networks require a highly dynamic, adaptive routing scheme to deal with the high rate of topology changes due to fading of indoor wireless channels. Besides that, energy consumption rate needs to be consistently distributed among sensor nodes and efficient utilization of battery power is essential. If only the link reliability metric is considered in the routing scheme, it may create long hops routes, and the high quality paths will be frequently used. This leads to shorter lifetime of such paths; thereby the entire network's lifetime will be significantly minimized. This paper briefly presents a reliable load-balanced routing (RLBR) scheme for indoor ad hoc wireless sensor networks, which integrates routing information from different layers. The proposed scheme aims to redistribute the relaying workload and the energy usage among relay sensor nodes to achieve balanced energy dissipation; thereby maximizing the functional network lifetime. RLBR scheme was tested and benchmarked against the TinyOS-2.x implementation of MintRoute on an indoor testbed comprising 20 Mica2 motes and low power listening (LPL) link layer provided by CC1000 radio. RLBR scheme consumes less energy for communications while reducing topology repair latency and achieves better connectivity and communication reliability in terms of end-to-end packets delivery performance
Application of near infrared reflectance spectroscopy in screening of fresh cassava (Manihot esculenta crantz) storage roots for provitamin A carotenoids
A developed Near Infrared Reflectance Spectroscopy (NIRS) calibration equation was used for determining provitamin A carotenoids contents of different trials of fresh yellow root cassava genotypes using a total of 50 cassava genotypes scanned twice by NIRS from 400 nm to 2498 nm. The NIRS calibration equations were used to predict the β-cryptoxanthin, 13-cis β-carotene, trans β-carotene, 9-cis β -carotene, total β-carotene and total carotenoid concentrations of the samples. The predicted values for total carotenoids (TC-pred) ranged from 3.93 μg g–1 to 10.51 μg g–1 with mean of 7.07 ± 2.55 μg g–1 for International Collaborative Trials (ICT), 7.97–11.03 μg g–1 fresh weight with mean of 9.40 ± 0.76 μg g–1 for yellow root trial 8 (Multi-location Uniform Yield Trial) and 6.38–10.44 μg g–1 with mean of 8.74 ± 1.07 μg g–1 for yellow root trial 9 (Multilocation Advanced Yield Trial). Total carotenoids results using reference spectrophotometric method (TC-spec) ranged from 2.57 μg g–1 to 9.97 μg g–1 with mean of 5.66 ± 2.99 μg g–1 for ICT, 6.55–8.74 μg g–1 with mean of 7.74 ± 0.64 μg g–1 for yellow root trial 8 and 4.22–11.00 μg g–1 with mean of 7.57 ± 1.54 μg g–1 for yellow root trail 9. There is significant (P ≤ 0.001) positive correlation (r = 0.55) between TC-pred by NIRS and TC-spec. Also, significant (P ≤ 0.001) positive correlation (r = 0.52) exist between trans β-carotene predicted by NIRS and high-performance liquid chromatography reference. The developed NIRS calibration equations could be used to predict total carotenoids and trans β-carotene content of yellow root cassava and serve as rapid and cost-effective screening method for large cassava sample sets
A New Measurement of the Average FUV Extinction Curve
We have measured the extinction curve in the far-ultraviolet wavelength
region of (900 -- 1200 A) using spectra obtained with the Berkeley EUV/FUV
spectrometer during the ORFEUS-I and the ORFEUS-II missions in 1993 and 1996.
From the complete sample of early-type stars observed during these missions,
we have selected pairs of stars with the same spectral type but different
reddenings to measure the differential FUV extinction. We model the effects of
molecular hydrogen absorption and exclude affected regions of the spectrum to
determine the extinction from dust alone. We minimize errors from inaccuracies
in the cataloged spectral types of the stars by making our own determinations
of spectral types based on their IUE spectra. We find substantial scatter in
the curves of individual star pairs and present a detailed examination of the
uncertainties and their effects on each extinction curve. We find that, given
the potentially large uncertainties inherent in using the pair method at FUV
wavelengths, a careful analysis of measurement uncertainties is critical to
assessing the true dust extinction. We present a new measurement of the average
far-ultraviolet extinction curve to the Lyman limit; our new measurement is
consistent with an extrapolation of the standard extinction curve of Savage &
Mathis (1979).Comment: 13 pages text, 7 figures 4 tables. Sent as gzipped tar, with ms.tex
and 7 figure
Realization of an all-optical zero to π cross-phase modulation jump
We report on the experimental demonstration of an all-optical π cross-phase modulation jump. By performing a preselection, an optically induced unitary transformation, and then a postselection on the polarization degree of freedom, the phase of the output beam acquires either a zero or π phase shift (with no other possible values). The postselection results in optical loss in the output beam. An input state may be chosen near the resulting phase singularity, yielding a pi phase shift even for weak interaction strengths. The scheme is experimentally demonstrated using a coherently prepared dark state in a warm atomic cesium vapor
D-term Inflation and Nonperturbative Kahler Potential of Dilaton
We study the -term inflation scenario with a nonperturbative K\"ahler
potential of the dilaton field. Although the FI term which leads an
inflationary expansion is given by the derivative of the K\"ahler potential
with respect to the dilaton in heterotic string models with anomalous U(1), the
too large magnitude is problematic for a viable -term inflation. In this
paper, we point out that the K\"ahler potential with a nonperturbative term can
reduce the magnitude of FI term to desired values while both the dilaton
stabilization and -term domination in the potential are realized by
nonperturbative superpotential.Comment: 13 pages, latex, 3 figure
Mirror Symmetry, Mirror Map and Applications to Calabi-Yau Hypersurfaces
Mirror Symmetry, Picard-Fuchs equations and instanton corrected Yukawa
couplings are discussed within the framework of toric geometry. It allows to
establish mirror symmetry of Calabi-Yau spaces for which the mirror manifold
had been unavailable in previous constructions. Mirror maps and Yukawa
couplings are explicitly given for several examples with two and three moduli.Comment: 59 pages. Some changes in the references, a few minor points have
been clarifie
Microbial ecology of Thiobacillus ferrooxidans
FINAL TECHNICAL REPORT
TO
U.S. DEPARTMENT OF THE INTERIOR
Geological Survey
Washington. D.C.The contents of this report were developed in part under a grant from
the Department of the Interior, U.S. Geological Survey. Grant number 14-08-0001-61313
Innermost Stable Circular Orbit of a Spinning Particle in Kerr Spacetime
We study stability of a circular orbit of a spinning test particle in a Kerr
spacetime. We find that some of the circular orbits become unstable in the
direction perpendicular to the equatorial plane, although the orbits are still
stable in the radial direction. Then for the large spin case ($S < \sim O(1)),
the innermost stable circular orbit (ISCO) appears before the minimum of the
effective potential in the equatorial plane disappears. This changes the radius
of ISCO and then the frequency of the last circular orbit.Comment: 25 pages including 8 figure
Fuels treatment and wildfire effects on runoff from Sierra Nevada mixed-conifer forests
We applied an eco-hydrologic model (Regional Hydro-Ecologic Simulation System [RHESSys]), constrained with spatially distributed field measurements, to assess the impacts of forest-fuel treatments and wildfire on hydrologic fluxes in two Sierra Nevada firesheds. Strategically placed fuels treatments were implemented during 2011–2012 in the upper American River in the central Sierra Nevada (43 km2) and in the upper Fresno River in the southern Sierra Nevada (24 km2). This study used the measured vegetation changes from mechanical treatments and modelled vegetation change from wildfire to determine impacts on the water balance. The well-constrained headwater model was transferred to larger catchments based on geologic and hydrologic similarities. Fuels treatments covered 18% of the American and 29% of the Lewis catchment. Averaged over the entire catchment, treatments in the wetter central Sierra Nevada resulted in a relatively light vegetation decrease (8%), leading to a 12% runoff increase, averaged over wet and dry years. Wildfire with and without forest treatments reduced vegetation by 38% and 50% and increased runoff by 55% and 67%, respectively. Treatments in the drier southern Sierra Nevada also reduced the spatially averaged vegetation by 8%, but the runoff response was limited to an increase of less than 3% compared with no treatment. Wildfire following treatments reduced vegetation by 40%, increasing runoff by 13%. Changes to catchment-scale water-balance simulations were more sensitive to canopy cover than to leaf area index, indicating that the pattern as well as amount of vegetation treatment is important to hydrologic response
Self-forces on extended bodies in electrodynamics
In this paper, we study the bulk motion of a classical extended charge in
flat spacetime. A formalism developed by W. G. Dixon is used to determine how
the details of such a particle's internal structure influence its equations of
motion. We place essentially no restrictions (other than boundedness) on the
shape of the charge, and allow for inhomogeneity, internal currents,
elasticity, and spin. Even if the angular momentum remains small, many such
systems are found to be affected by large self-interaction effects beyond the
standard Lorentz-Dirac force. These are particularly significant if the
particle's charge density fails to be much greater than its 3-current density
(or vice versa) in the center-of-mass frame. Additional terms also arise in the
equations of motion if the dipole moment is too large, and when the
`center-of-electromagnetic mass' is far from the `center-of-bare mass' (roughly
speaking). These conditions are often quite restrictive. General equations of
motion were also derived under the assumption that the particle can only
interact with the radiative component of its self-field. These are much simpler
than the equations derived using the full retarded self-field; as are the
conditions required to recover the Lorentz-Dirac equation.Comment: 30 pages; significantly improved presentation; accepted for
publication in Phys. Rev.
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