Brane Cosmology and KK Gravitinos

The cosmology of KK gravitinos in models with extra dimensions is considered. The main result is that the production of such KK modes is not compatible with an epoch of non--standard expansion after inflation. This is so because the BBN constraint on the zero mode forces the reduced five dimensional Planck mass $M_5$ down to values much smaller than the usual four dimensional one, but this in turn implies many KK states available for a given temperature. Once these states are taken into account one finds that there is no $M_5$ for which the produced KK gravitinos satisfy BBN and overclosure constraints. This conclusion holds for both flat and warped models in which only gravity propagates in the full spacetime.Comment: 19 pages, references added, IoP styl

Large-Scale Magnetic Fields, Dark Energy and QCD

Cosmological magnetic fields are being observed with ever increasing correlation lengths, possibly reaching the size of superclusters, therefore disfavouring the conventional picture of generation through primordial seeds later amplified by galaxy-bound dynamo mechanisms. In this paper we put forward a fundamentally different approach that links such large-scale magnetic fields to the cosmological vacuum energy. In our scenario the dark energy is due to the Veneziano ghost (which solves the $U(1)_A$ problem in QCD). The Veneziano ghost couples through the triangle anomaly to the electromagnetic field with a constant which is unambiguously fixed in the standard model. While this interaction does not produce any physical effects in Minkowski space, it triggers the generation of a magnetic field in an expanding universe at every epoch. The induced energy of the magnetic field is thus proportional to cosmological vacuum energy: $\rho_{EM}\simeq B^2 \simeq (\frac{\alpha}{4\pi})^2 \rho_{DE}$, $\rho_{DE}$ hence acting as a source for the magnetic energy $\rho_{EM}$. The corresponding numerical estimate leads to a magnitude in the nG range. There are two unique and distinctive predictions of our proposal: an uninterrupted active generation of Hubble size correlated magnetic fields throughout the evolution of the universe; the presence of parity violation on the enormous scales $1/H$, which apparently has been already observed in CMB. These predictions are entirely rooted into the standard model of particle physics.Comment: jhep style, 22 pages, v2 with updated estimates and extended discussion on parity violation, v3 as published (references updated

A new approach to data publication in ocean sciences

Data are collected from ocean sciences activities that range from a single investigator working in a laboratory to large teams of scientists cooperating on big, multinational, global ocean research projects. What these activities have in common is that all result in data, some of which are used as the basis for publications in peer-reviewed journals.However, two major problems regarding data remain. First, many data valuable for understanding ocean physics, chemistry, geology, biology, and how the oceans operate in the Earth system are never archived or made accessible to other scientists. Data underlying traditional journal articles are often difficult to obtain. Second, when scientists do contribute data to databases, their data become freely available, with little acknowledgment and no contribution to their career advancement. To address these problems, stronger ties must be made between data repositories and academic journals, and a “digital backbone” needs to be created for data related to journal publications

Weekly Versus Monthly Testosterone Administration On Fast and Slow Skeletal Muscle Fibers in Older Adult Males

Context: In older adults, loss of mobility due to sarcopenia is exacerbated in men with low serum T. T replacement therapy is known to increase muscle mass and strength, but the effect of weekly (WK) vs monthly (MO) administration on specific fiber types is unknown. Objective: To determine the efficacy of WK vs MO T replacement on the size and functional capacity of individual fast and slow skeletal muscle fiber types. Design, Setting, and Patients: Subjects were randomized into a 5-month, double-blind, placebo-controlled trial. All subjects (ages, 61–71 y) were community-dwelling men who had T levels \u3c 500 ng/dL. Intervention: Subjects were dosed weekly for 5 months, receiving continuous T (WK, n = 5; 100 mg T enanthate, im injection), monthly cycled T (MO, n = 7; alternating months of T and placebo), or placebo (n = 7). Muscle biopsies of the vastus lateralis were obtained before and after treatment. Main Outcome Measures: Main outcomes for individual slow and fast fibers included fiber diameter, peak force (P0), rate of tension development, maximal shortening velocity, peak power, and Ca2+ sensitivity. Results: Both treatments increased fiber diameter and peak power, with WK treatment 5-fold more effective than MO in increasing type I fiber P0. WK effects on fiber diameter and force were 1.5-fold higher in slow fibers compared to fast fibers. In fast type II fibers, diameter and P0 increased similarly between treatments. The increased power was entirely due to increased fiber size and force. Conclusions: In conclusion, T replacement effects were fiber-type dependent, restricted to increases in cell size, P0, and peak power, and dependent on the paradigm selected (WK vs MO)

The Masses Of The B-Stars In The High Galactic Latitude Eclipsing Binary IT Lib

A number of blue stars which appear to be similar to Population I B-stars in the star forming regions of the galactic disk are found more than 1 kpc from the galactic plane. Uncertainties about the true distances and masses of these high latitude B-stars has fueled a debate as to their origin and evolutionary status. The eclipsing binary IT Lib is composed of two B-stars, is approximately one kiloparsec above the galactic plane, and is moving back toward the plane. Observations of the light and velocity curves presented here lead to the conclusion that the B-stars in this system are massive young main-sequence stars. While there are several possible explanations, it appears most plausible that the IT Lib system formed in the disk about 30 million years ago and was ejected on a trajectory taking it to its present position.Comment: 26 pages, 3 figures, accepted for publication in the PASP (January 2003

Perturbation of magnetostatic modes observed by ferromagnetic resonance force microscopy

Magnetostatic modes of yttrium iron garnet (YIG) films are investigated by ferromagnetic resonance force microscopy. A thin-film "probe" magnet at the tip of a compliant cantilever introduces a local inhomogeneity in the internal field of the YIG sample. This influences the shape of the sample's magnetostatic modes, thereby measurably perturbing the strength of the force coupled to the cantilever. We present a theoretical model that explains these observations; it shows that the tip-induced variation of the internal field creates either a local "potential barrier" or "potential well" for the magnetostatic waves. The data and model together indicate that local magnetic imaging of ferromagnets is possible, even in the presence of long-range spin coupling, through the introduction of localized magnetostatic modes predicted to arise from sufficiently strong tip fields

Premise Selection for Mathematics by Corpus Analysis and Kernel Methods

Smart premise selection is essential when using automated reasoning as a tool for large-theory formal proof development. A good method for premise selection in complex mathematical libraries is the application of machine learning to large corpora of proofs. This work develops learning-based premise selection in two ways. First, a newly available minimal dependency analysis of existing high-level formal mathematical proofs is used to build a large knowledge base of proof dependencies, providing precise data for ATP-based re-verification and for training premise selection algorithms. Second, a new machine learning algorithm for premise selection based on kernel methods is proposed and implemented. To evaluate the impact of both techniques, a benchmark consisting of 2078 large-theory mathematical problems is constructed,extending the older MPTP Challenge benchmark. The combined effect of the techniques results in a 50% improvement on the benchmark over the Vampire/SInE state-of-the-art system for automated reasoning in large theories.Comment: 26 page

Piloting a commercial broiler production model for smallholders in Rwanda

Increasing food security is premised on improving economic empowerment as well as nutrition across the household. As such, developmentprojects across Africa are integrating nutrition objectives into pro-poor value chain development interventions toincrease dietary diversity and incomes. To meet the micronutrient demands of a growingpopulation, Rwanda seeks to increase the production of and access to meat-basedproteins, including chicken production. Despite Rwanda’s recent rapid economic growth,there is a limited supply of and access to animal-sourced protein nationally. A hybridbroiler model, which integrates elements of smallholder and larger intensive poultrymodels, could be a sustainable approach. A model piloted in Musanze District, Rwanda.Tworore Inkoko, Twunguke (TI) (Let’s raise chickens for profit!) uses an intensive, 100-bird model with the aim of training and supporting 750 smallholder farmers through aninnovative private-sector-based train-the-trainer approach. This study examines the initial evidence from TI production data to determine (a) the performance of improved broiler breeds in a Rwandan smallholder context, (b) farmer profitability, and (c) household consumption of broilers. With 18 months of flock data, average livability of flocks was 89%, similar to large-scale, modern broiler sector averages globally. Tworore Inkoko smallholders have been profitable, with average profit increasing as they gain experience and grow-out new flocks (profit ranging between 28 and 89 USD per flock). Birds set aside for consumption by farmers ranged from an average of 0.31 to 4.00 birds per flock, settling at closer to three per flock by the end of the first 18 months. Smallholder farmers in Rwanda have the potential to be successful through this model. Lessons learned from the rollout of this pilot project will be used to inform potential scale-up of this hybrid model across Rwanda, as well as other pro-poor value chains looking to increase food security by generating incomes and increasing access to highly nutritious and balanced diets.&nbsp