Galaxy peculiar velocities and evolution-bias

Galaxy bias can be split into two components: a formation-bias based on the locations of galaxy creation, and an evolution-bias that details their subsequent evolution. In this letter we consider evolution-bias in the peaks model. In this model, galaxy formation takes place at local maxima in the density field, and we analyse the subsequent peculiar motion of these galaxies in a linear model of structure formation. The peak restriction yields differences in the velocity distribution and correlation between the galaxy and the dark matter fields, which causes the evolution-bias component of the total bias to evolve in a scale-dependent way. This mechanism naturally gives rise to a change in shape between galaxy and matter correlation functions that depends on the mean age of the galaxy population. This model predicts that older galaxies would be more strongly biased on large scales compared to younger galaxies. Our arguments are supported by a Monte-Carlo simulation of galaxy pairs propagated using the Zel'dovich-approximation for describing linear peculiar galaxy motion.Comment: 5 pages, 4 figures, MNRAS accepte

The age of the oldest Open Clusters

We determine ages of 71 old Open Clusters by a two-step method: we use main-squence fitting to 10 selected clusters, in order to obtain their distances, and derive their ages from comparison with our own isochrones used before for Globular Clusters. We then calibrate the morphological age indicator delta(V), which can be obtained for all remaining clusters, in terms of age and metallicity. Particular care is taken to ensure consistency in the whole procedure. The resulting Open Cluster ages connect well to our previous Globular Cluster results. From the Open Cluster sample, as well as from the combined sample, questions regarding the formation process of Galactic components are addressed. The age of the oldest open clusters (NGC6791 and Be17) is of the order of 10 Gyr. We determine a delay by 2.0+-1.5 Gyr between the start of the halo and thin disk formation, whereas thin and thick disk started to form approximately at the same time. We do not find any significant age-metallicity relationship for the open cluster sample. The cumulative age distribution of the whole open cluster sample shows a moderately significant (~2sigma level) departure from the predictions for an exponentially declining dissolution rate with timescale of 2.5 Gyr. The cumulative age distribution does not show any trend with galactocentric distance, but the clusters with larger height to the Galactic plane have an excess of objects between 2-4 and 6 Gyr with respect to their counterpart closer to the plane of the Galaxy.Comment: Astronomy & Astrophysics, in pres

The Housing and Support Needs of Older People with Visual Impairment

Visual impairment is one of the most prevalent anddisabling conditions among older people, and yet verylittle research has been conducted that could inform thedevelopment of appropriate public services. In order toaddress this deficiency, Thomas Pocklington Trust fundedresearch to examine the housing and support needs of 400visually impaired people aged over 55.The study found that:? There is little professional recognition, or offers of help andadvice for the anxiety, depression, and sense of profoundloss that people experience with late onset of visualimpairment.? Both blind and partially sighted people need timely andholistic assessment, rehabilitation, affordable equipment andregular review.? People with sight loss do not wish to leave their homes.Home is the epicentre of a mental map that assistsorientation and continuity following sight loss.? Social isolation and lack of human contact are majorproblems for people with sight loss.? People with sight loss have poor knowledge of supportgroups, community services and/or specialist housingoptions for older people with visual impairment. Visual impairment is one of the most prevalent anddisabling conditions among older people, and yet verylittle research has been conducted that could inform thedevelopment of appropriate public services. In order toaddress this deficiency, Thomas Pocklington Trust fundedresearch to examine the housing and support needs of 400visually impaired people aged over 55.The study found that:? There is little professional recognition, or offers of help andadvice for the anxiety, depression, and sense of profoundloss that people experience with late onset of visualimpairment.? Both blind and partially sighted people need timely andholistic assessment, rehabilitation, affordable equipment andregular review.? People with sight loss do not wish to leave their homes.Home is the epicentre of a mental map that assistsorientation and continuity following sight loss.? Social isolation and lack of human contact are majorproblems for people with sight loss.? People with sight loss have poor knowledge of supportgroups, community services and/or specialist housingoptions for older people with visual impairment

Meeting the needs of older peoplewith visual impairment: social care orsocial exclusion?

This paper is based on the research study ?Housing and supportneeds of older people with visual impairment ? experiences andchallenges? (Hanson et al, 2002).1The full findings of this study are reported in another occasionalpaper produced by Thomas Pocklington Trust.2 It is, however, usefulto state that this study found evidence that sight loss in later life hassignificant emotional consequences, often unacknowledged byprofessionals. It also showed how older people with visionimpairment often have their own coping strategies, but are less ablethan sighted peers to carry out certain daily tasks.The study suggested that professionals should offer sensitive andtimely support, in a more collaborative manner, and that serviceshave to be monitored and evaluated to avoid wide-ranging needsremaining unmet. In respect of the home environment, researchindicated that adequate and accessible domestic space in which todo housework safely, low vision equipment and the provision ofovernight accommodation for guests and carers was required.Most participants in the study wished to stay in their homes andneighbourhoods. When asked about possible alternative options,participants emphasised the importance of location and sufficientspace. If they were considering supported housing, they requiredfull information about how it addressed their particular needs.This paper focuses on whether older people with visual impairmentare vulnerable to social exclusion if their social care needs are unmet. In particular, this paper argues that:? Greater professional collaboration is required to improve eyeclinic and community support services.? Relevant staff should aim to provide timely and holisticassessments of need.? Older people with vision impairment have significant needs asregards home care support, access to information, psychologicalstress and social isolation.? Initiatives such as peer support groups and resource centres offeropportunities to tackle social exclusion arising from unmetneeds. This paper is based on the research study ?Housing and supportneeds of older people with visual impairment ? experiences andchallenges? (Hanson et al, 2002).1The full findings of this study are reported in another occasionalpaper produced by Thomas Pocklington Trust.2 It is, however, usefulto state that this study found evidence that sight loss in later life hassignificant emotional consequences, often unacknowledged byprofessionals. It also showed how older people with visionimpairment often have their own coping strategies, but are less ablethan sighted peers to carry out certain daily tasks.The study suggested that professionals should offer sensitive andtimely support, in a more collaborative manner, and that serviceshave to be monitored and evaluated to avoid wide-ranging needsremaining unmet. In respect of the home environment, researchindicated that adequate and accessible domestic space in which todo housework safely, low vision equipment and the provision ofovernight accommodation for guests and carers was required.Most participants in the study wished to stay in their homes andneighbourhoods. When asked about possible alternative options,participants emphasised the importance of location and sufficientspace. If they were considering supported housing, they requiredfull information about how it addressed their particular needs.This paper focuses on whether older people with visual impairmentare vulnerable to social exclusion if their social care needs are unmet. In particular, this paper argues that:? Greater professional collaboration is required to improve eyeclinic and community support services.? Relevant staff should aim to provide timely and holisticassessments of need.? Older people with vision impairment have significant needs asregards home care support, access to information, psychologicalstress and social isolation.? Initiatives such as peer support groups and resource centres offeropportunities to tackle social exclusion arising from unmetneeds

Censusing manatees: a report on the feasibility of using aerial surveys and mark and recapture techniques to conduct a population survey of the West Indian Manatee

This report results from an invitation to review the needs and prospects for capture-recapture and aerial census studies of the manatee (Trichechus manatus) in Florida. Three aerial reconnaissance flights provided a first hand view of manatee habitats, as follows: May 3, Suwannee River to Kings Bay and Crystal River (Rathbun, Eberhardt), May 4, Vero Beach to Ft. Lauderdale and Ft. Myers by way of Whitewater Bay (Rose, Percival, Eberhardt), and May 5, Cape Canaveral to Jacksonville, St. Johns River and Blue Spring (Rose, Kinnaird, Eberhardt). (24 page document

Selected topics in Planck-scale physics

We review a few topics in Planck-scale physics, with emphasis on possible manifestations in relatively low energy. The selected topics include quantum fluctuations of spacetime, their cumulative effects, uncertainties in energy-momentum measurements, and low energy quantum-gravity phenomenology. The focus is on quantum-gravity-induced uncertainties in some observable quantities. We consider four possible ways to probe Planck-scale physics experimentally: 1. looking for energy-dependent spreads in the arrival time of photons of the same energy from GRBs; 2. examining spacetime fluctuation-induced phase incoherence of light from extragalactic sources; 3. detecting spacetime foam with laser-based interferometry techniques; 4. understanding the threshold anomalies in high energy cosmic ray and gamma ray events. Some other experiments are briefly discussed. We show how some physics behind black holes, simple clocks, simple computers, and the holographic principle is related to Planck-scale physics. We also discuss a formulation of the Dirac equation as a difference equation on a discrete Planck-scale spacetime lattice, and a possible interplay between Planck-scale and Hubble-scale physics encoded in the cosmological constant (dark energy).Comment: 31 pages, 1 figure; minor changes; to appear in Mod. Phys. Lett. A as a Brief Revie

A general computer program for the Bell detection loophole

The difference between ideal experiments to test Bell's weak nonlocality and the real experiments leads to loopholes. Ideal experiments involve either inequalities (Bell) or equalities (Greenberger, Horne, Zeilinger). Every real experiment has its own critical inequalities, which are almost all more complicated than the corresponding ideal inequalities and equalities. If one of these critical inequalities is violated, then the detection loophole is closed, with no further assumptions. If all the critical inequalities are satisfied, then it remains open, unless further assumptions are made. The computer program described here and published on the website http://www.strings.ph.qmw.ac.uk/QI/main.htm obtains the critical inequalities for any real experiment, given the number of allowed settings of the angles and the corresponding possible output signals for a single run. Given all the necessary conditional probabilities or rates, it tests whether all these inequalities are satisfied.Comment: 10 pages, no figures. Revised version with additional reference to Pitowski and Svozi

The impact of systematic uncertainties in stellar parameters on integrated spectra of stellar populations

In this paper we investigate a hitherto unexplored source of potentially significant error in stellar population synthesis (SPS) models, caused by systematic uncertainties associated with the three fundamental stellar atmospheric parameters; effective temperature T_eff, surface gravity g, and iron abundance [Fe/H]. All SPS models rely on calibrations of T_eff, logg and [Fe/H] scales, which are implicit in stellar models, isochrones and synthetic spectra, and are explicitly adopted for empirical spectral libraries. We assess the effect of a mismatch in scales between isochrones and spectral libraries (the two key components of SPS models) and quantify the effects on 23 commonly used diagnostic line indices. We find that typical systematic offsets of 100K in T_eff, 0.15 dex in [Fe/H] and/or 0.25 dex in logg significantly alter inferred absolute ages of simple stellar populations (SSPs) and that in some circumstances, relative ages also change. Offsets in T_eff, logg and [Fe/H] scales for a scaled-solar SSP produce deviations from the model which can mimic the effects of altering abundance ratios to non-scaled-solar chemical compositions, and could also be spuriously interpreted as evidence for a more complex population, especially when multiple-index or full-SED fitting methods are used. We stress that the behavior we find can potentially affect any SPS models, whether using full integrated spectra or fitting functions to determine line strengths. We present measured offsets in 23 diagnostic line indices and urge caution in the over-interpretation of line-index data for stellar populations.Comment: 14 pages, including 4 figures and 3 tables. Accepted for publication in Ap