7,489 research outputs found
Limits on Arcminute Scale Cosmic Microwave Background Anisotropy with the BIMA Array
We have used the Berkeley-Illinois-Maryland-Association (BIMA) millimeter
array outfitted with sensitive cm-wave receivers to search for Cosmic Microwave
Background (CMB) anisotropies on arcminute scales. The interferometer was
placed in a compact configuration which produces high brightness sensitivity,
while providing discrimination against point sources. Operating at a frequency
of 28.5 GHz, the FWHM primary beam of the instrument is 6.6 arcminutes. We have
made sensitive images of seven fields, five of which where chosen specifically
to have low IR dust contrast and be free of bright radio sources. Additional
observations with the Owens Valley Radio Observatory (OVRO) millimeter array
were used to assist in the location and removal of radio point sources.
Applying a Bayesian analysis to the raw visibility data, we place limits on CMB
anisotropy flat-band power Q_flat = 5.6 (+3.0 -5.6) uK and Q_flat < 14.1 uK at
68% and 95% confidence. The sensitivity of this experiment to flat band power
peaks at a multipole of l = 5470, which corresponds to an angular scale of
approximately 2 arcminutes. The most likely value of Q_flat is similar to the
level of the expected secondary anisotropies.Comment: 15 pages, 5 figures, LaTex, aas2pp4.sty, ApJ submitte
Mechanism of Vanadium Leaching during Surface Weathering of Basic Oxygen Furnace Steel Slag Blocks: A Microfocus X-ray Absorption Spectroscopy and Electron Microscopy Study
© 2017 American Chemical Society. Basic oxygen furnace (BOF) steelmaking slag is enriched in potentially toxic V which may become mobilized in high pH leachate during weathering. BOF slag was weathered under aerated and air-excluded conditions for 6 months prior to SEM/EDS and ΌXANES analysis to determine V host phases and speciation in both primary and secondary phases. Leached blocks show development of an altered region in which free lime and dicalcium silicate phases were absent and Ca-Si-H was precipitated (CaCO 3 was also present under aerated conditions). ΌXANES analyses show that V was released to solution as V(V) during dicalcium silicate dissolution and some V was incorporated into neo-formed Ca-Si-H. Higher V concentrations were observed in leachate under aerated conditions than in the air-excluded leaching experiment. Aqueous V concentrations were controlled by Ca 3 (VO 4 ) 2 solubility, which demonstrate an inverse relationship between Ca and V concentrations. Under air-excluded conditions Ca concentrations were controlled by dicalcium silicate dissolution and Ca-Si-H precipitation, leading to relatively high Ca and correspondingly low V concentrations. Formation of CaCO 3 under aerated conditions provided a sink for aqueous Ca, allowing higher V concentrations limited by kinetic dissolution rates of dicalcium silicate. Thus, V release may be slowed by the precipitation of secondary phases in the altered region, improving the prospects for slag reuse
Alternative Fourier Expansions for Inverse Square Law Forces
Few-body problems involving Coulomb or gravitational interactions between
pairs of particles, whether in classical or quantum physics, are generally
handled through a standard multipole expansion of the two-body potentials. We
discuss an alternative based on a compact, cylindrical Green's function
expansion that should have wide applicability throughout physics. Two-electron
"direct" and "exchange" integrals in many-electron quantum systems are
evaluated to illustrate the procedure which is more compact than the standard
one using Wigner coefficients and Slater integrals.Comment: 10 pages, latex/Revtex4, 1 figure
Investment of Both Essential Fatty and Amino Acids to Immunity Varies Depending on Reproductive Stage.
Tradeâoffs among the key lifeâhistory traits of reproduction and immunity have been widely documented. However, the currency in use is not wellâunderstood. We investigated how reproducing female sideâblotched lizards, Uta stansburiana, allocate lipids versus proteins when given an immune challenge. We tested whether lizards would invest more in reproduction or immunity depending on reproductive stage. Females were given stable isotopes (15Nâleucine and 13Câ1âpalmitic acid), maintained on a regular diet and given either a cutaneous biopsy or a sham biopsy (control). Stable isotopes were monitored and analyzed in feces and uric acid, skin biopsies, eggs, and toe clips. We found that lizards deposited both proteins and lipids into their healing wounds (immuneâchallenged), skin (control), and eggs (all) and that catabolism of proteins exceeded incorporation into tissue during woundâhealing. Specifically, we found that healed biopsies of wounded animals had more leucine and palmitic acid than the nonregrown skin biopsies taken from unwounded control animals. Earlier in reproduction, lizards invested relatively more labeled proteins into healing their wound tissue, but not into unwounded skin of control animals. Thus, reproduction is sometimes favored over selfâmaintenance, but only in later reproductive stages. Finally, we documented positive relationships among the amount of palmitic acid deposited in the eggs, the amount of food eaten, and the amount of palmitic acid excreted, suggesting higher turnover rates of lipids in lizards investing highly in their eggs
Escape from noisy intermittent repellers
Intermittent or marginally-stable repellers are commonly associated with a
power law decay in the survival fraction. We show here that the presence of
weak additive noise alters the spectrum of the Perron - Frobenius operator
significantly giving rise to exponential decays even in systems that are
otherwise regular. Implications for ballistic transport in marginally stable
miscrostructures are briefly discussed.Comment: 3 ps figures include
Bayesian model comparison applied to the Explorer-Nautilus 2001 coincidence data
Bayesian reasoning is applied to the data by the ROG Collaboration, in which
gravitational wave (g.w.) signals are searched for in a coincidence experiment
between Explorer and Nautilus. The use of Bayesian reasoning allows, under well
defined hypotheses, even tiny pieces of evidence in favor of each model to be
extracted from the data. The combination of the data of several experiments can
therefore be performed in an optimal and efficient way. Some models for
Galactic sources are considered and, within each model, the experimental result
is summarized with the likelihood rescaled to the insensitivity limit value
(`` function''). The model comparison result is given in in terms of
Bayes factors, which quantify how the ratio of beliefs about two alternative
models are modified by the experimental observationComment: 16 pages, 4 figures. Presented at the GWDAW2002 conference, held in
Kyoto on Dec.,2002. This version includes comments by the referees of CQG,
which has accepted the paper for pubblication in the special issue of the
conference. In particular, note that in Eq. 12 there was a typeset error. As
suggested by one of the referees, a uniform prior in Log(alpha) has also been
considere
A systematic review of longitudinal studies investigating the association between early life maternal depression and offspring ADHD
Objective:
The systematic review sought to understand the relationship between maternal depression and later ADHD in children.
Method:
Three databases were used to identify the studies (Medline, Web of Science and PsychInfo) resulting in 1,223 studies being screened and 14 articles being included in the review.
Results:
The majority of studies (N = 11) reported a significant relationship between maternal depression (across both prenatal and postnatal periods) and ADHD symptoms in children. This relationship remained significant when temperament, or past ADHD symptoms were controlled for. Several methodological issues were identified including; overreliance on maternal report and parental ADHD not being accounted for in most studies.
Conclusion:
The review adds to the literature regarding the temporal relationship between maternal depression and the development of ADHD in children, and thus supports the case for improving access to mental health services for mothers as a preventative strategy in the development of child psychopathology
Non-parametric comparison of histogrammed two-dimensional data distributions using the Energy Test
When monitoring complex experiments, comparison is often made between regularly acquired histograms of data and reference histograms which represent the ideal state of the equipment. With the larger HEP experiments now ramping up, there is a need for automation of this task since the volume of comparisons could overwhelm human operators. However, the two-dimensional histogram comparison tools available in ROOT have been noted in the past to exhibit shortcomings. We discuss a newer comparison test for two-dimensional histograms, based on the Energy Test of Aslan and Zech, which provides more conclusive
discrimination between histograms of data coming from different distributions than methods provided in a recent ROOT release.The Science and Technology Facilities Council, U
Experienced migratory songbirds do not display goal-ward orientation after release following a cross-continental displacement: an automated telemetry study
The ability to navigate implies that animals have the capability to compensate for geographical displacement and return to their initial goal or target. Although some species are capable of adjusting their direction after displacement, the environmental cues used to achieve this remain elusive. Two possible cues are geomagnetic parameters (magnetic map hypothesis) or atmospheric odour-forming gradients (olfactory map hypothesis). In this study, we examined both of these hypotheses by surgically deactivating either the magnetic or olfactory sensory systems in experienced white-throated sparrows (Zonotrichia albicollis) captured in southern Ontario, Canada, during spring migration. Treated, sham-treated, and intact birds were then displaced 2,200 km west to Saskatchewan, Canada. Tracking their initial post-displacement migration using an array of automated VHF receiving towers, we found no evidence in any of the groups for compensatory directional response towards their expected breeding grounds. Our results suggest that white-throated sparrows may fall back to a simple constant-vector orientation strategy instead of performing true navigation after they have been geographically displaced to an unfamiliar area during spring migration. Such a basic strategy may be more common than currently thought in experienced migratory birds and its occurrence could be determined by habitat preferences or range size
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