Phase-Sensitive Tetracrystal Pairing-Symmetry Measurements and Broken Time-Reversal Symmetry States of High Tc Superconductors

A detailed analysis of the symmetric tetracrystal geometry used in phase-sensitive pairing symmetry experiments on high Tc superconductors is carried out for both bulk and surface time-reversal symmetry-breaking states, such as the d+id' and d+is states. The results depend critically on the substrate geometry. In the general case, for the bulk d+id' (or d+is) state, the measured flux quantization should in general not be too different from that obtained in the pure d-wave case, provided |d'| << |d| (or |s| << |d|). However, in one particular high symmetry geometry, the d+id' state gives results that allow it to be distinguished from the pure d and the d + is states. Results are also given for the cases where surface d+is or d+id' states occur at a [110] surface of a bulk d-wave superconductor. Remarkably, in the highest symmetry geometry, a number of the broken time-reversal symmetry states discussed above give flux quantization conditions usually associated with states not having broken time- reversal symmetry.Comment: 6 page

A lower limit on the dark particle mass from dSphs

We use dwarf spheroidal galaxies as a tool to attempt to put precise lower limits on the mass of the dark matter particle, assuming it is a sterile neutrino. We begin by making cored dark halo fits to the line of sight velocity dispersions as a function of projected radius (taken from Walker et al. 2007) for six of the Milky Way's dwarf spheroidal galaxies. We test Osipkov-Merritt velocity anisotropy profiles, but find that no benefit is gained over constant velocity anisotropy. In contrast to previous attempts, we do not assume any relation between the stellar velocity dispersions and the dark matter ones, but instead we solve directly for the sterile neutrino velocity dispersion at all radii by using the equation of state for a partially degenerate neutrino gas (which ensures hydrostatic equilibrium of the sterile neutrino halo). This yields a 1:1 relation between the sterile neutrino density and velocity dispersion, and therefore gives us an accurate estimate of the Tremaine-Gunn limit at all radii. By varying the sterile neutrino particle mass, we locate the minimum mass for all six dwarf spheroidals such that the Tremaine-Gunn limit is not exceeded at any radius (in particular at the centre). We find sizeable differences between the ranges of feasible sterile neutrino particle mass for each dwarf, but interestingly there exists a small range 270-280eV which is consistent with all dSphs at the 1-$\sigma$ level.Comment: 13 pages, 2 figures, 1 tabl

Indirect Dark Matter Detection from Dwarf Satellites: Joint Expectations from Astrophysics and Supersymmetry

We present a general methodology for determining the gamma-ray flux from annihilation of dark matter particles in Milky Way satellite galaxies, focusing on two promising satellites as examples: Segue 1 and Draco. We use the SuperBayeS code to explore the best-fitting regions of the Constrained Minimal Supersymmetric Standard Model (CMSSM) parameter space, and an independent MCMC analysis of the dark matter halo properties of the satellites using published radial velocities. We present a formalism for determining the boost from halo substructure in these galaxies and show that its value depends strongly on the extrapolation of the concentration-mass (c(M)) relation for CDM subhalos down to the minimum possible mass. We show that the preferred region for this minimum halo mass within the CMSSM with neutralino dark matter is ~10^-9-10^-6 solar masses. For the boost model where the observed power-law c(M) relation is extrapolated down to the minimum halo mass we find average boosts of about 20, while the Bullock et al (2001) c(M) model results in boosts of order unity. We estimate that for the power-law c(M) boost model and photon energies greater than a GeV, the Fermi space-telescope has about 20% chance of detecting a dark matter annihilation signal from Draco with signal-to-noise greater than 3 after about 5 years of observation

Can forest management based on natural disturbances maintain ecological resilience?

Given the increasingly global stresses on forests, many ecologists argue that managers must maintain ecological resilience: the capacity of ecosystems to absorb disturbances without undergoing fundamental change. In this review we ask: Can the emerging paradigm of natural-disturbance-based management (NDBM) maintain ecological resilience in managed forests? Applying resilience theory requires careful articulation of the ecosystem state under consideration, the disturbances and stresses that affect the persistence of possible alternative states, and the spatial and temporal scales of management relevance. Implementing NDBM while maintaining resilience means recognizing that (i) biodiversity is important for long-term ecosystem persistence, (ii) natural disturbances play a critical role as a generator of structural and compositional heterogeneity at multiple scales, and (iii) traditional management tends to produce forests more homogeneous than those disturbed naturally and increases the likelihood of unexpected catastrophic change by constraining variation of key environmental processes. NDBM may maintain resilience if silvicultural strategies retain the structures and processes that perpetuate desired states while reducing those that enhance resilience of undesirable states. Such strategies require an understanding of harvesting impacts on slow ecosystem processes, such as seed-bank or nutrient dynamics, which in the long term can lead to ecological surprises by altering the forest's capacity to reorganize after disturbance

Friedmann-like equations for High Energy Area of Universe

In this paper, evolution of the high energy area of universe, through the scenario of 5 dimensional (5D) universe, has been studied. For this purpose, we solve Einstein equations for 5D metric and 5D perfect fuid to derive Friedmann-like equations. Then we obtain the evolution of scale factor and energy density with respect to both space-like and time-like extra dimensions. We obtain the novel equations for the space-like extra dimension and show that the matter with zero pressure cannot exist in the bulk. Also, for dark energy fuid and vacuum fluid, we have both accelerated expansion and contraction in the bulk.Comment: 9 pages, Accepted to publication in IJTP 26 June 2012. arXiv admin note: substantial text overlap with arXiv:1202.497

Dark Matter signals from Draco and Willman 1: Prospects for MAGIC II and CTA

The next generation of ground-based Imaging Air Cherenkov Telescopes (IACTs) will play an important role in indirect dark matter searches. In this article, we consider two particularly promising candidate sources for dark matter annihilation signals, the nearby dwarf galaxies Draco and Willman 1, and study the prospects of detecting such a signal for the soon-operating MAGIC II telescope system as well as for the planned installation of CTA, taking special care of describing the experimental features that affect the detectional prospects. For the first time in such a study, we fully take into account the effect of internal bremsstrahlung, which has recently been shown to considerably enhance, in some cases, the gamma-ray flux at the high energies where Atmospheric Cherenkov Telescopes operate, thus leading to significantly harder annihilation spectra than traditionally considered. While the detection of the spectral features introduced by internal bremsstrahlung would constitute a smoking gun signature for dark matter annihilation, we find that for most models the overall flux still remains at a level that will be challenging to detect unless one adopts rather (though by no means overly) optimistic astrophysical assumptions about the distribution of dark matter in the dwarfs.Comment: 10 pages, 4 figures, minor changes, matches the published version (JCAP

Cosmological parameters from SDSS and WMAP

We measure cosmological parameters using the three-dimensional power spectrum P(k) from over 200,000 galaxies in the Sloan Digital Sky Survey (SDSS) in combination with WMAP and other data. Our results are consistent with a ``vanilla'' flat adiabatic Lambda-CDM model without tilt (n=1), running tilt, tensor modes or massive neutrinos. Adding SDSS information more than halves the WMAP-only error bars on some parameters, tightening 1 sigma constraints on the Hubble parameter from h~0.74+0.18-0.07 to h~0.70+0.04-0.03, on the matter density from Omega_m~0.25+/-0.10 to Omega_m~0.30+/-0.04 (1 sigma) and on neutrino masses from <11 eV to <0.6 eV (95%). SDSS helps even more when dropping prior assumptions about curvature, neutrinos, tensor modes and the equation of state. Our results are in substantial agreement with the joint analysis of WMAP and the 2dF Galaxy Redshift Survey, which is an impressive consistency check with independent redshift survey data and analysis techniques. In this paper, we place particular emphasis on clarifying the physical origin of the constraints, i.e., what we do and do not know when using different data sets and prior assumptions. For instance, dropping the assumption that space is perfectly flat, the WMAP-only constraint on the measured age of the Universe tightens from t0~16.3+2.3-1.8 Gyr to t0~14.1+1.0-0.9 Gyr by adding SDSS and SN Ia data. Including tensors, running tilt, neutrino mass and equation of state in the list of free parameters, many constraints are still quite weak, but future cosmological measurements from SDSS and other sources should allow these to be substantially tightened.Comment: Minor revisions to match accepted PRD version. SDSS data and ppt figures available at http://www.hep.upenn.edu/~max/sdsspars.htm

Measurement of the Bottom contribution to non-photonic electron production in p+pp+p collisions at s\sqrt{s} =200 GeV

The contribution of $B$ meson decays to non-photonic electrons, which are mainly produced by the semi-leptonic decays of heavy flavor mesons, in $p+p$ collisions at $\sqrt{s} =$ 200 GeV has been measured using azimuthal correlations between non-photonic electrons and hadrons. The extracted $B$ decay contribution is approximately 50% at a transverse momentum of $p_{T} \geq 5$ GeV/$c$. These measurements constrain the nuclear modification factor for electrons from $B$ and $D$ meson decays. The result indicates that $B$ meson production in heavy ion collisions is also suppressed at high $p_{T}$.Comment: 6 pages, 4 figures, accepted by PR

Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

Aloidendron barberae

Aloidendron is a very small genus of seven tree aloes in the family Asphodelaceae, described as recently as 2013, ranging from South Africa to Mozambique, with a large disjunction to Somalia, Yemen and Saudi Arabia. Aloidendron barberae is recorded from South Africa, Swaziland and southern Mozambique. However, the records for Mozambique are queried here and it is suggested that these actually relate to its closest relative, Aloidendron tongaense, a smaller tree only 4-8 m tall, which may be endemic to Mozambique. Aloidendron barberae is the largest alooid, growing to 20 m tall and is copiously dichotomously branched. Its taxonomic and nomenclatural history are outlined. Its habitat, natural distribution, ecology and cultivation are discussed, accompanied by a full description and reproduction of a specially commissioned watercolour painting