Statistics of Substructures in Dark Matter Haloes

We study the amount and distribution of dark matter substructures within dark matter haloes, using a large set of high-resolution simulations ranging from group size to cluster size haloes, and carried our within a cosmological model consistent with WMAP 7-year data. In particular, we study how the measured properties of subhaloes vary as a function of the parent halo mass, the physical properties of the parent halo, and redshift. The fraction of halo mass in substructures increases with increasing mass. There is, however, a very large halo-to-halo scatter that can be explained only in part by a range of halo physical properties, e.g. concentration. At given halo mass, less concentrated haloes contain significantly larger fractions of mass in substructures because of the reduced strength of tidal disruption. Most of the substructure mass is located at the outskirts of the parent haloes, in relatively few massive subhaloes. This mass segregation appears to become stronger at increasing redshift, and should reflect into a more significant mass segregation of the galaxy population at different cosmic epochs. When haloes are accreted onto larger structures, their mass is significantly reduced by tidal stripping. Haloes that are more massive at the time of accretion (these should host more luminous galaxies) are brought closer to the centre on shorter time-scales by dynamical friction, and therefore suffer of a more significant stripping. The halo merger rate depends strongly on the environment with substructure in more massive haloes suffering more important mergers than their counterparts residing in less massive systems. This should translate into a different morphological mix for haloes of different mass.Comment: 13 pages, 11 figures and 1 table. MNRAS 2011 in pres

Band Calculation for Ce-compounds on the basis of Dynamical Mean Field Theory

The band calculation scheme for $f$ electron compounds is developed on the basis of the dynamical mean field theory (DMFT) and the LMTO method. The auxiliary impurity problem is solved by a method named as NCA$f^{2}$v', which includes the correct exchange process of the $f^{1} \to f^{2}$ virtual excitation as the vertex correction to the non-crossing approximation (NCA) for the $f^{1} \to f^{0}$ fluctuation. This method leads to the correct magnitude of the Kondo temperature, $T_{\rm K}$, and makes it possible to carry out quantitative DMFT calculation including the crystalline field (CF) and the spin-orbit (SO) splitting of the self-energy. The magnetic excitation spectra are also calculated to estimate $T_{\rm K}$. It is applied to Ce metal and CeSb at T=300 K as the first step. In Ce metal, the hybridization intensity (HI) just below the Fermi energy is reduced in the DMFT band. The photo-emission spectra (PES) have a conspicuous SO side peak, similar to that of experiments. $T_{\rm K}$ is estimated to be about 70 K in $\gamma$-Ce, while to be about 1700 K in $\alpha$-Ce. In CeSb, the double-peak-like structure of PES is reproduced. In addition, $T_{\rm K}$ which is not so low is obtained because HI is enhanced just at the Fermi energy in the DMFT band.Comment: 30pages, 18 figure

The phase diagram of Yang-Mills theory with a compact extra dimension

We present a non-perturbative study of the phase diagram of SU(2) Yang-Mills theory in a five-dimensional spacetime with a compact extra dimension. The non-renormalizable theory is regularized on an anisotropic lattice and investigated through numerical simulations in a regime characterized by a hierarchy between the scale of low-energy physics, the inverse compactification radius, and the cutoff scale. We map out the structure of the phase diagram and the pattern of lines corresponding to fixed values of the ratio between the mass of the fifth component of the gauge field and the non-perturbative mass gap of the four-dimensional modes. We discuss different limits of the model, and comment on the implications of our findings.Comment: 17 pages, 9 figure

Engaging Undergraduates in Science Research: Not Just About Faculty Willingness.

Despite the many benefits of involving undergraduates in research and the growing number of undergraduate research programs, few scholars have investigated the factors that affect faculty members' decisions to involve undergraduates in their research projects. We investigated the individual factors and institutional contexts that predict faculty members' likelihood of engaging undergraduates in their research project(s). Using data from the Higher Education Research Institute's 2007-2008 Faculty Survey, we employ hierarchical generalized linear modeling to analyze data from 4,832 science, technology, engineering, and mathematics (STEM) faculty across 194 institutions to examine how organizational citizenship behavior theory and social exchange theory relate to mentoring students in research. Key findings show that faculty who work in the life sciences and those who receive government funding for their research are more likely to involve undergraduates in their research project(s). In addition, faculty at liberal arts or historically Black colleges are significantly more likely to involve undergraduate students in research. Implications for advancing undergraduate research opportunities are discussed

Observational Constraints on the Modified Gravity Model (MOG) Proposed by Moffat: Using the Magellanic System

A simple model for the dynamics of the Magellanic Stream (MS), in the framework of modified gravity models is investigated. We assume that the galaxy is made up of baryonic matter out of context of dark matter scenario. The model we used here is named Modified Gravity (MOG) proposed by Moffat (2005). In order to examine the compatibility of the overall properties of the MS under the MOG theory, the observational radial velocity profile of the MS is compared with the numerical results using the $\chi^2$ fit method. In order to obtain the best model parameters, a maximum likelihood analysis is performed. We also compare the results of this model with the Cold Dark Matter (CDM) halo model and the other alternative gravity model that proposed by Bekenstein (2004), so called TeVeS. We show that by selecting the appropriate values for the free parameters, the MOG theory seems to be plausible to explain the dynamics of the MS as well as the CDM and the TeVeS models.Comment: 14 pages, 3 Figures, accepted in Int. J. Theor. Phy

Blood-Labyrinth Barrier Permeability in Menière Disease and Idiopathic Sudden Sensorineural Hearing Loss: Findings on Delayed Postcontrast 3D-FLAIR MRI

Background and purposeMenière disease and idiopathic sudden sensorineural hearing loss can have overlapping clinical presentation and may have similar pathophysiology. Prior studies using postcontrast 3D-FLAIR MR imaging suggest abnormal blood-labyrinth barrier permeability in both conditions, but the 2 diseases have not been directly compared by using the same imaging techniques. We hypothesized that delayed postcontrast 3D-FLAIR MR imaging would show differences in blood-labyrinth barrier permeability between Menière disease and idiopathic sudden sensorineural hearing loss.Materials and methodsPatients with unilateral Menière disease (n = 32) and unilateral idiopathic sudden sensorineural hearing loss (n = 11) imaged with delayed postcontrast 3D-FLAIR MR imaging were retrospectively studied. Signal intensities of the medulla and perilymph of the cochlear basal turns of both ears in each patient were measured in a blinded fashion. Cochlea/medulla ratios were calculated for each ear as a surrogate for blood-labyrinth barrier permeability. The ears were segregated by clinical diagnosis.ResultsCochlea/medulla ratio was higher in symptomatic ears of patients with Menière disease (12.6 ± 7.4) than in patients with idiopathic sudden sensorineural hearing loss (5.7 ± 2.0) and asymptomatic ears of patients with Menière disease (8.0 ± 3.1), indicating increased blood-labyrinth barrier permeability in Menière disease ears. The differences in cochlea/medulla ratio between symptomatic and asymptomatic ears were significantly higher in Menière disease than in idiopathic sudden sensorineural hearing loss. Asymptomatic ears in patients with Menière disease showed higher cochlea/medulla ratio than symptomatic and asymptomatic ears in patients with idiopathic sudden sensorineural hearing loss.ConclusionsIncreased cochlea/medulla ratio indicates increased blood-labyrinth barrier permeability in Menière disease compared with idiopathic sudden sensorineural hearing loss. Increased cochlea/medulla ratio in asymptomatic ears of patients with Menière disease also suggests an underlying systemic cause of Menière disease and may provide a pathophysiologic biomarker

Carbon brainprint - An estimate of the intellectual contribution of research institutions to reducing greenhouse gas emissions

This is the accepted manuscript of a paper published in Process Safety and Environmental Protection (Chatterton J, et al., Process Safety and Environmental Protection, 2015, 96, 74-81, doi:10.1016/j.psep.2015.04.008). The final version is available at http://dx.doi.org/10.1016/j.psep.2015.04.008Research and innovation have considerable, currently unquantified potential to reduce greenhouse gas emissions by, for example, increasing energy efficiency. Furthermore, the process of knowledge transfer in itself can have a significant impact on reducing emissions, by promoting awareness and behavioural change. The concept of the ‘carbon brainprint’ was proposed to convey the intellectual contribution of higher education institutions to the reduction of greenhouse gas emissions by other parties through research and teaching/training activities. This paper describes an investigation of the feasibility of quantifying the carbon brainprint, through six case studies. The potential brainprint of higher education institutes is shown to be significant: up to 500 kt CO2e/year for one project. The most difficult aspect is attributing the brainprint among multiple participants in joint projects.The Carbon Brainprint project was supported by the Higher Education Funding Council for England (HEFCE) under its Leading Sustainable Development in Higher Education programme, with support for case studies from Santander Universities. HEFCE, Research Councils UK and the Carbon Trust were members of the Steering Committee, which provided guidance, but did not direct the research. The Carbon Trust also advised on best practice in carbon footprinting. We are grateful to the many university staff at Cranfield, Cambridge and Reading Universities who shared their work with us so enthusiastically. We also thank the external partners and clients for the projects on which these case studies are based: Rolls-Royce plc, the ETI NOVA consortium, IGD, the Environment Agency, Esso, Repsol YPF, Carnego Systems Ltd. and Newera Controls Ltd

High-resolution mass models of dwarf galaxies from LITTLE THINGS

We present high-resolution rotation curves and mass models of 26 dwarf galaxies from LITTLE THINGS. LITTLE THINGS is a high-resolution Very Large Array HI survey for nearby dwarf galaxies in the local volume within 11 Mpc. The rotation curves of the sample galaxies derived in a homogeneous and consistent manner are combined with Spitzer archival 3.6 micron and ancillary optical U, B, and V images to construct mass models of the galaxies. We decompose the rotation curves in terms of the dynamical contributions by baryons and dark matter halos, and compare the latter with those of dwarf galaxies from THINGS as well as Lambda CDM SPH simulations in which the effect of baryonic feedback processes is included. Being generally consistent with THINGS and simulated dwarf galaxies, most of the LITTLE THINGS sample galaxies show a linear increase of the rotation curve in their inner regions, which gives shallower logarithmic inner slopes alpha of their dark matter density profiles. The mean value of the slopes of the 26 LITTLE THINGS dwarf galaxies is alpha =-0.32 +/- 0.24 which is in accordance with the previous results found for low surface brightness galaxies (alpha = -0.2 +/- 0.2) as well as the seven THINGS dwarf galaxies (alpha =-0.29 +/- 0.07). However, this significantly deviates from the cusp-like dark matter distribution predicted by dark-matter-only Lambda CDM simulations. Instead our results are more in line with the shallower slopes found in the Lambda CDM SPH simulations of dwarf galaxies in which the effect of baryonic feedback processes is included. In addition, we discuss the central dark matter distribution of DDO 210 whose stellar mass is relatively low in our sample to examine the scenario of inefficient supernova feedback in low mass dwarf galaxies predicted from recent Lambda SPH simulations of dwarf galaxies where central cusps still remain.Peer reviewe

A Dual-Beam Irradiation Facility for a Novel Hybrid Cancer Therapy

In this paper we present the main ideas and discuss both the feasibility and the conceptual design of a novel hybrid technique and equipment for an experimental cancer therapy based on the simultaneous and/or sequential application of two beams, namely a beam of neutrons and a CW (continuous wave) or intermittent sub-terahertz wave beam produced by a gyrotron for treatment of cancerous tumors. The main simulation tools for the development of the computer aided design (CAD) of the prospective experimental facility for clinical trials and study of such new medical technology are briefly reviewed. Some tasks for a further continuation of this feasibility analysis are formulated as well.Comment: 18 pages, 3 tables, 8 figures, 50 reference