4,854 research outputs found

    An analysis of the duties of general clerical workers in the General Electric Company

    Full text link
    Thesis (M.A.)--Boston University 1949. This item was digitized by the Internet Archive

    On the relevance of chaos for halo stars in the Solar Neighbourhood

    Get PDF
    We show that diffusion due to chaotic mixing in the Neighbourhood of the Sun may not be as relevant as previously suggested in erasing phase space signatures of past Galactic accretion events. For this purpose, we analyse Solar Neighbourhood-like volumes extracted from cosmological simulations that naturally account for chaotic orbital behaviour induced by the strongly triaxial and cuspy shape of the resulting dark matter haloes, among other factors. In the approximation of an analytical static triaxial model, our results show that a large fraction of stellar halo particles in such local volumes have chaos onset times (i.e., the timescale at which stars commonly associated with chaotic orbits will exhibit their chaotic behaviour) significantly larger than a Hubble time. Furthermore, particles that do present a chaotic behaviour within a Hubble time do not exhibit significant diffusion in phase space.Comment: 20 pages, 16 figures. Accepted for publication in MNRA

    Psychological interventions for the treatment of depression, anxiety, alcohol misuse or anger in armed forces veterans and their families: systematic review and meta-analysis protocol.

    Get PDF
    This is the final version. Available from the publisher via the DOI in this record.BACKGROUND: Evidence highlights a high prevalence of common mental health disorders in armed forces veterans and their families, with depression, anxiety, alcohol misuse and anger being more common than PTSD. This paper presents a protocol for a systematic review and meta-analysis to identify existing randomised controlled trial (RCT) research testing the effectiveness of psychological interventions for these difficulties in armed forces veterans and their family members. METHODS: Electronic databases (CENTRAL, PsycInfo, MEDLINE, CINAHL, The Cochrane Register of Clinical Trials, EMBASE and ASSIA) will be searched to identify suitable studies for inclusion in the review supplemented by forward and backward reference checking, grey literature searches and contact with subject authors. Research including armed forces veterans and their family members will be included in the review with research including serving personnel or individuals under the age of 18 being excluded. Few RCTs examining the treatment of depression, anxiety, alcohol misuse or anger exist in armed forces veterans to date. The primary outcome will be symptomatic change following intervention for these difficulties. The secondary outcomes will include methodological aspects of interest such as discharge type and recruitment setting if data permits. In the event that the number of studies identified is too low to undertake a meta-analysis, a narrative review will be conducted. Quality assessment will be undertaken using the Cochrane Collaboration Tool and Cochran's Q statistic calculated to test for heterogeneity as suggested by the Cochrane handbook. DISCUSSION: The review will examine the findings of existing intervention research for depression, anxiety, alcohol misuse or anger in armed forces veterans and their families, along with any effect sizes that may exist. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42016036676.Libor Fun

    Optical diode based on the chirality of guided photons

    Get PDF
    Photons are nonchiral particles: their handedness can be both left and right. However, when light is transversely confined, it can locally exhibit a transverse spin whose orientation is fixed by the propagation direction of the photons. Confined photons thus have chiral character. Here, we employ this to demonstrate nonreciprocal transmission of light at the single-photon level through a silica nanofibre in two experimental schemes. We either use an ensemble of spin-polarised atoms that is weakly coupled to the nanofibre-guided mode or a single spin-polarised atom strongly coupled to the nanofibre via a whispering-gallery-mode resonator. We simultaneously achieve high optical isolation and high forward transmission. Both are controlled by the internal atomic state. The resulting optical diode is the first example of a new class of nonreciprocal nanophotonic devices which exploit the chirality of confined photons and which are, in principle, suitable for quantum information processing and future quantum optical networks

    Selecting ultra-faint dwarf candidate progenitors in cosmological N-body simulations at high redshifts

    Full text link
    The smallest satellites of the Milky Way ceased forming stars during the epoch of reionization and thus provide archaeological access to galaxy formation at z>6z>6. Numerical studies of these ultra-faint dwarf galaxies (UFDs) require expensive cosmological simulations with high mass resolution that are carried out down to z=0z=0. However, if we are able to statistically identify UFD host progenitors at high redshifts \emph{with relatively high probabilities}, we can avoid this high computational cost. To find such candidates, we analyze the merger trees of Milky Way type halos from the high-resolution Caterpillar{\it Caterpillar} suite of dark matter only simulations. Satellite UFD hosts at z=0z=0 are identified based on four different abundance matching (AM) techniques. All the halos at high redshifts are traced forward in time in order to compute the probability of surviving as satellite UFDs today. Our results show that selecting potential UFD progenitors based solely on their mass at z=12 (8) results in a 10\% (20\%) chance of obtaining a surviving UFD at z=0z=0 in three of the AM techniques we adopted. We find that the progenitors of surviving satellite UFDs have lower virial ratios (η\eta), and are preferentially located at large distances from the main MW progenitor, while they show no correlation with concentration parameter. Halos with favorable locations and virial ratios are 3\approx 3 times more likely to survive as satellite UFD candidates at z=0.z=0.Comment: 12 pages, 7 figures, accepted for publication at MNRAS after minor revision

    The Caterpillar Project: A Large Suite of Milky Way Sized Halos

    Full text link
    We present the largest number of Milky Way sized dark matter halos simulated at very high mass (\sim10410^4 M_\odot/particle) and temporal resolution (\sim5 Myrs/snapshot) done to date, quadrupling what is currently available in the literature. This initial suite consists of the first 24 halos of the CaterpillarCaterpillar ProjectProject (www.caterpillarproject.org) whose project goal of 60 - 70 halos will be made public when complete. We resolve \sim20,000 gravitationally bound subhalos within the virial radius of each host halo. Over the ranges set by our spatial resolution our convergence is excellent and improvements were made upon current state-of-the-art halo finders to better identify substructure at such high resolutions (e.g., on average we recover \sim4 subhalos in each host halo above 108^8 M_\odot which would have otherwise not been found using conventional methods). For our relaxed halos, the inner profiles are reasonably fit by Einasto profiles (α\alpha = 0.169 ±\pm 0.023) though this depends on the relaxed nature and assembly history of a given halo. Averaging over all halos, the substructure mass fraction is fm,subs=0.121±0.041f_{m,subs} = 0.121 \pm 0.041, and mass function slope is dNN/dMM1.88±0.10M\propto M^{-1.88 \pm 0.10} though we find scatter in the normalizations for fixed halo mass due to more concentrated hosts having less subhalos at fixed subhalo mass. There are no biases stemming from Lagrangian volume selection as all Lagrangian volume types are included in our sample. Our detailed contamination study of 264 low resolution halos has resulted in obtaining very large and unprecedented, high-resolution regions around our host halos for our target resolution (sphere of radius \sim1.4±0.41.4 \pm 0.4 Mpc) allowing for accurate studies of low mass dwarf galaxies at large galactocentric radii and the very first stellar systems at high redshift (zz \geq 10).Comment: 19 pages; 14 figures; 6 tables; Received September 3, 2015; Accepted November 15, 2015; Published February 2, 201
    corecore