704 research outputs found
Group-based trajectory analysis of physical activity change in a U.S. weight loss intervention
Background: The obesity epidemic is a global concern. Standard behavioral treatment including increased physical activity, reduced energy intake, and behavioral change counseling is an effective lifestyle intervention for weight loss. Purpose: To identify distinct step count patterns among weight loss intervention participants, examine weight loss differences by trajectory group, and examine baseline factors associated with trajectory group membership. Methods: Both groups received group-based standard behavioral treatment while the experimental group received up to 30 additional, one-on-one self-efficacy enhancement sessions. Data were analyzed using group-based trajectory modeling, analysis of variance, chi-square tests, and multinomial logistic regression. Results: Participants (N = 120) were mostly female (81.8%) and white (73.6%) with a mean (SD) body mass index of 33.2 (3.8) kg/m2. Four step count trajectory groups were identified: active (>10,000 steps/day; 11.7%), somewhat active (7500â10,000 steps/day; 28.3%), low active (5000â7500 steps/day; 27.5%), and sedentary (<5000 steps/day; 32.5%). Percent weight loss at 12 months increased incrementally by trajectory group (5.1% [5.7%], 7.8% [6.9%], 8.0% [7.4%], and 13.63% [7.0%], respectively; P = .001). At baseline, lower body mass index and higher perceived health predicted membership in the better performing trajectory groups. Conclusions: Within a larger group of adults in a weight loss intervention, 4 distinct trajectory groups were identified and group membership was associated with differential weight loss
Organic and conventional tomato cropping systems.
Among several alternative agricultural systems have been developed, organic agriculture has deserved increasing interest from. The objective of this paper was comparing both organic (OS) and conventional (CS) tomato cropping systems for varieties DĂ©bora and Santa Clara, through an interdisciplinary study. The experiment was set up in a randomized blocks design with six replicates, in a dystrophic Ultisol plots measuring 25 ÂŽ 17 m. Cropping procedures followed by either local conventional or organic growers practices recommendations. Fertilization in the OS was done with organic compost, single superphosphate, dolomitic limes (5L, 60 g, and 60 g per pit), and sprayed twice a week with biofertilizer. Fertilization in the CS was done with 200 g 4-14-8 (NPK) per pit and, after planting, 30 g N, 33 g K and 10.5 g P per pit; from 52 days after planting forth, plants were sprayed once a week with foliar fertilizer. In the CS, a blend of insecticides, fungicides and miticides was sprayed twice a week, after planting. In the OS, extracts of black pepper, garlic, and Eucalyptus; Bordeaux mixture, and biofertilizer, were applied twice a week to control diseases and pests. Tomato spotted wilt was the most important disease in the OS, resulting in smaller plant development, number of flower clusters and yield. In the CS, the disease was kept under control, and the population of thrips, the virus vector, occurred at lower levels than in the OS. Variety Santa Clara presented greater incidence of the viral disease, and for this reason had a poorer performance than 'DĂ©bora', especially in the OS. Occurrence of Liriomyza spp. was significantly smaller in the OS, possibly because of the greater frequency of Chrysoperla. The CS had smaller incidence of leaf spots caused by Septoria lycopersici and Xanthomonas vesicatoria. However, early blight and fruit rot caused by Alternaria solani occurred in larger numbers. No differences were observed with regard to the communities of fungi and bacteria in the phylloplane, and to the occurrence of weeds
Transmission Properties of the oscillating delta-function potential
We derive an exact expression for the transmission amplitude of a particle
moving through a harmonically driven delta-function potential by using the
method of continued-fractions within the framework of Floquet theory. We prove
that the transmission through this potential as a function of the incident
energy presents at most two real zeros, that its poles occur at energies
(), and that the
poles and zeros in the transmission amplitude come in pairs with the distance
between the zeros and the poles (and their residue) decreasing with increasing
energy of the incident particle. We also show the existence of non-resonant
"bands" in the transmission amplitude as a function of the strength of the
potential and the driving frequency.Comment: 21 pages, 12 figures, 1 tabl
Sneutrino-induced like sign dilepton signal with conserved R-parity
Lepton number violation could be manifest in the sneutrino sector of
supersymmetric extensions of the standard model with conserved R-parity. Then
sneutrinos decay partly into the ``wrong sign charged lepton'' final state, if
kinematically accessible. In sneutrino pair production or associated single
sneutrino production, the signal then is a like sign dilepton final state.
Under favourable circumstances, such a signal could be visible at the LHC or a
next generation linear collider for a relative sneutrino mass-splitting of
order and sneutrino width of order (1 GeV). On the
other hand, the like sign dilepton event rate at the TEVATRON is probably too
small to be observable.Comment: 19 pages, 14 Figures. Section about LSD at LHC and TEVATRON added.
Previous Title "Single sneutrino production and the wrong charged lepton
signal
Annihilation vs. Decay: Constraining dark matter properties from a gamma-ray detection
Most proposed dark matter candidates are stable and are produced thermally in
the early Universe. However, there is also the possibility of unstable (but
long-lived) dark matter, produced thermally or otherwise. We propose a strategy
to distinguish between dark matter annihilation and/or decay in the case that a
clear signal is detected in gamma-ray observations of Milky Way dwarf
spheroidal galaxies with gamma-ray experiments. The sole measurement of the
energy spectrum of an indirect signal would render the discrimination between
these cases impossible. We show that by examining the dependence of the
intensity and energy spectrum on the angular distribution of the emission, the
origin could be identified as decay, annihilation, or both. In addition, once
the type of signal is established, we show how these measurements could help to
extract information about the dark matter properties, including mass,
annihilation cross section, lifetime, dominant annihilation and decay channels,
and the presence of substructure. Although an application of the approach
presented here would likely be feasible with current experiments only for very
optimistic dark matter scenarios, the improved sensitivity of upcoming
experiments could enable this technique to be used to study a wider range of
dark matter models.Comment: 29 pp, 8 figs; replaced to match published version (minor changes and
some new references
Particle Emissions from Domestic Gas Cookers
The authors experimentally studied the formation of submicron particles from a domestic gas cooker in a compartment free from external particle sources. The effects of fuel (methane, natural gas, odorant-free natural gas), primary aeration, flow rate, and fuel sulphur content on particle emissions were investigated. The experiments confirmed reports from literature that blue burning flames of domestic gas cookers emit submicron particles. The particle number concentrations varied in the range 103-106 particles/cm3, depending on the fuel, flow rate, and primary air addition. The diameters of the emitted particles were found to have a mean value of about 7 nm for partially premixed flames, increasing to âŒ10 nm for nonpremixed flames. The quantity of primary air had a strong impact on the particle emissions, showing a minimum at a primary aeration level of 60-65%. Presence of sulphur in small quantities may enhance particle formation under some conditions, but results were not conclusive
Suppression of charge-ordering and appearance of magnetoresistance in a spin-cluster glass manganite La0.3Ca0.7Mn0.8Cr0.2O3
The magnetic properties of electron-doped manganite La0.3Ca0.7MnO3 and
La0.3Ca0.7Mn0.8Cr0.2O3 polycrystalline samples prepared by sol-gel technique
have been investigated between 5 and 300 K in magnetic fields ranging from 0 to
5 T. The transition at 260 K, attributed to charge ordering in La0.3Ca0.7MnO3,
is completely suppressed in the Cr-substituted sample while the onset of a
magnetic remanence followed by the appearance of a magnetic irreversibility at
lower temperatures is observed in both samples. These features indicate that
ferromagnetic clusters coexist with either an antiferromagnetic phase for
La0.3Ca0.7MnO3 or a spin-cluster glass phase for La0.3Ca0.7Mn0.8Cr0.2O3 at the
lowest temperatures. The exponential temperature dependence of the resistivity
for the Cr-substituted sample is consistent with the small polaron hopping
model for 120 K < T < 300 K, while the data are better described by Mott's
hopping mechanism for T < 120 K. Whereas the parent compound La0.3Ca0.7MnO3 is
known to show no magnetoresistance, a large negative magnetoresistance is
observed in the La0.3Ca0.7Mn0.8Cr0.2O3 sample below 120 K. The appearance of
the CMR is attributed to spin dependent hopping between spin clusters and/or
between ferromagnetic domains
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