Description of Atmospheric Conditions at the Pierre Auger Observatory Using Meteorological Measurements and Models

Atmospheric conditions at the site of a cosmic ray observatory must be known well for reconstructing observed extensive air showers, especially when measured using the fluorescence technique. For the Pierre Auger Observatory, a sophisticated network of atmospheric monitoring devices has been conceived. Part of this monitoring was a weather balloon program to measure atmospheric state variables above the Observatory. To use the data in reconstructions of air showers, monthly models have been constructed. Scheduled balloon launches were abandoned and replaced with launches triggered by high-energetic air showers as part of a rapid monitoring system. Currently, the balloon launch program is halted and atmospheric data from numerical weather prediction models are used. A description of the balloon measurements, the monthly models as well as the data from the numerical weather prediction are presented

Cosmic Variance In the Transparency of the Intergalactic Medium After Reionization

Following the completion of cosmic reionization, the mean-free-path of ionizing photons was set by a population of Ly-limit absorbers. As the mean-free-path steadily grew, the intensity of the ionizing background also grew, thus lowering the residual neutral fraction of hydrogen in ionization equilibrium throughout the diffuse intergalactic medium (IGM). Ly-alpha photons provide a sensitive probe for tracing the distribution of this residual hydrogen at the end of reionization. Here we calculate the cosmic variance among different lines-of-sight in the distribution of the mean Ly-alpha optical depths. We find fractional variations in the effective post-reionization optical depth that are of order unity on a scale of ~100 co-moving Mpc, in agreement with observations towards high-redshift quasars. Significant contributions to these variations are provided by the cosmic variance in the density contrast on the scale of the mean-free-path for ionizing photons, and by fluctuations in the ionizing background induced by delayed or enhanced structure formation. Cosmic variance results in a highly asymmetric distribution of transmission through the IGM, with fractional fluctuations in Ly-alpha transmission that ar larger than in Ly-beta transmission.Comment: 7 pages 3 figures. Replaced with version accepted for publication in Ap

Hysteresis multicycles in nanomagnet arrays

We predict two new physical effects in arrays of single-domain nanomagnets by performing simulations using a realistic model Hamiltonian and physical parameters. First, we find hysteretic multicycles for such nanomagnets. The simulation uses continuous spin dynamics through the Landau-Lifshitz-Gilbert (LLG) equation. In some regions of parameter space, the probability of finding a multicycle is as high as ~0.6. We find that systems with larger and more anisotropic nanomagnets tend to display more multicycles. This result demonstrates the importance of disorder and frustration for multicycle behavior. We also show that there is a fundamental difference between the more realistic vector LLG equation and scalar models of hysteresis, such as Ising models. In the latter case, spin and external field inversion symmetry is obeyed but in the former it is destroyed by the dynamics, with important experimental implications.Comment: 7 pages, 2 figure

High-Redshift Galaxies: Their Predicted Size and Surface Brightness Distributions and Their Gravitational Lensing Probability

Direct observations of the first generation of luminous objects will likely become feasible over the next decade. The advent of the Next Generation Space Telescope (NGST) will allow imaging of numerous galaxies and mini-quasars at redshifts z>5. We apply semi-analytic models of structure formation to estimate the rate of multiple imaging of these sources by intervening gravitational lenses. Popular CDM models for galaxy formation yield a lensing optical depth of about 1% for sources at redshift 10. The expected slope of the luminosity function of the early sources implies an additional magnification bias of about 5, bringing the fraction of lensed sources at z=10 to about 5%. We estimate the angular size distribution of high-redshift disk galaxies and find that most of them are more extended than the resolution limit of NGST, roughly 0.06 arcseconds. We also show that there is only a modest redshift evolution in the mean surface brightness of galaxies at z>2. The expected increase by 1-2 orders of magnitude in the number of resolved sources on the sky, due to observations with NGST, will dramatically improve upon the statistical significance of existing weak lensing measurements. We show that, despite this increase in the density of sources, confusion noise from z>2 galaxies is expected to be small for NGST observations.Comment: 27 pages, 8 PostScript figures (of which two are new), revised version accepted for Ap

Defect related switching field reduction in small magnetic particle arrays

An array of 42 mum square, 3 mum thick garnet particles has been studied. The strong crystalline uniaxial anisotropy of these particles results in the stable remanent state being single domain with magnetization parallel to the film normal. Magneto-optic measurements of individual particles provide distribution statistics for the easy-axis switching field H-sw, and the in-plane hard-axis effective anisotropy field, H-eff, which induces the formation of a metastable stripe domain structure. Both H-sw and H-eff are much smaller than the crystalline anisotropy field. Micromagnetic simulations show that the small H-sw cannot be attributed to shape anisotropy, but is consistent with smooth, localized reductions in the crystalline anisotropy caused by defects in either the particles or the substrate

The kinetics of homogeneous melting beyond the limit of superheating

Molecular dynamics simulation is used to study the time-scales involved in the homogeneous melting of a superheated crystal. The interaction model used is an embedded-atom model for Fe developed in previous work, and the melting process is simulated in the microcanonical $(N, V, E)$ ensemble. We study periodically repeated systems containing from 96 to 7776 atoms, and the initial system is always the perfect crystal without free surfaces or other defects. For each chosen total energy $E$ and number of atoms $N$, we perform several hundred statistically independent simulations, with each simulation lasting for between 500 ps and 10 ns, in order to gather statistics for the waiting time $\tau_{\rm w}$ before melting occurs. We find that the probability distribution of $\tau_{\rm w}$ is roughly exponential, and that the mean value $<\tau_{\rm w} >$ depends strongly on the excess of the initial steady temperature of the crystal above the superheating limit identified by other researchers. The mean $$ also depends strongly on system size in a way that we have quantified. For very small systems of $\sim 100$ atoms, we observe a persistent alternation between the solid and liquid states, and we explain why this happens. Our results allow us to draw conclusions about the reliability of the recently proposed Z method for determining the melting properties of simulated materials, and to suggest ways of correcting for the errors of the method.Comment: 19 pages, 8 figure

Environmental Justice in India: The Manifestation of Neo-Dharmic Jurisprudence in Postmodern Public Law.

Within the last two decades, India has not only enacted specific legislation on environmental protection but has also virtually created a new fundamental right to a clean environment in the Constitution. The models and methods adopted in the Indian context appear, at first sight, similar to those in other common law systems. Yet, there are many subtle differences which have changed the structure and content of legal development in India. Indian environmental jurisprudence brings out the unique characteristics of a new legal order which has been gradually established in India. The distinguishing nature of this jurisprudence, as this thesis shows in detail, has three interconnected elements. First, the nature of the new Indian constitutional law regime accords greater importance to public concerns than protecting private interests. Current Indian jurisprudence shows an increased assertion of public accountability by enlarging the domain of public law. This has created new dimensions of justice based on a new public law rationale which reacts constructively to established common law models. Secondly, this jurisprudential development reflects certain aspects of Indian legal culture, through implicit and explicit reliance on autochthonous values and concepts of law, encapsulated in the Indian juristic postulate of dharma. The new developments reflect distinct elements of Indian dharmic legal culture, which are markedly different from common law postulates evolved out of an individualistic, property-based private law culture. Thirdly, the emerging Indian environmental jurisprudence bears testimony to the activist role of the Indian judiciary which has also had a significant impact in many areas other than environmental law. In short, the development of environmental jurisprudence in India manifests neo-dharmic jurisprudence in postmodern public law. It accommodates ideas currently voiced by experts around the world for protecting the environment, in forms modified by the legal culture of India

Impact of a theoretically based sex education programme (SHARE) delivered by teachers on NHS registered conceptions and terminations: final results of cluster randomised trial

&lt;b&gt;Objective&lt;/b&gt;: To assess the impact of a theoretically based sex education programme (SHARE) delivered by teachers compared with conventional education in terms of conceptions and terminations registered by the NHS. Design Follow-up of cluster randomised trial 4.5 years after intervention. &lt;b&gt;Setting&lt;/b&gt;: NHS records of women who had attended 25 secondary schools in east Scotland. &lt;b&gt;Participants&lt;/b&gt;: 4196 women (99.5% of those eligible). &lt;b&gt;Intervention&lt;/b&gt;: SHARE programme (intervention group) v existing sex education (control group). &lt;b&gt;Main outcome measure&lt;/b&gt;: NHS recorded conceptions and terminations for the achieved sample linked at age 20. &lt;b&gt;Results&lt;/b&gt;: In an "intention to treat" analysis there were no significant differences between the groups in registered conceptions per 1000 pupils (300 SHARE v 274 control; difference 26, 95% confidence interval –33 to 86) and terminations per 1000 pupils (127 v 112; difference 15, –13 to 42) between ages 16 and 20. &lt;b&gt;Conclusions&lt;/b&gt;: This specially designed sex education programme did not reduce conceptions or terminations by age 20 compared with conventional provision. The lack of effect was not due to quality of delivery. Enhancing teacher led school sex education beyond conventional provision in eastern Scotland is unlikely to reduce terminations in teenagers

Interventions utilising contact with people with disabilities to improve children's attitudes towards disability: A systematic review and meta-analysis.

This is the author accepted manuscript.The final version is available from Elsevier via the DOI in this record.BACKGROUND: Children with disabilities are often the target of prejudice from their peers. The effects of prejudice include harmful health consequences. The Contact Hypothesis has previously shown to promote positive attitudes towards a range of social groups. OBJECTIVE: To conduct a systematic review and meta-analysis on the effectiveness of school-based interventions for improving children's attitudes towards disability through contact with people with disabilities. METHODS: A comprehensive search was conducted across multiple databases. Studies were included if it evaluated an intervention that aimed to improve children's attitudes towards disability and involved either direct (in-person) or indirect (e.g., extended) contact with people with disabilities. Data were synthesised in a meta-analysis. RESULTS: Twelve studies met the inclusion criteria. Of these, 11 found significant effects: six used direct contact, two used extended contact, two used parasocial (media-based) contact and one used guided imagined contact. One parasocial contact intervention found no significant effects. Three meta-analyses showed direct contact (d = 0.55, 95% CI 0.20 to 0.90) and extended contact (d = 0.61, 95% CI 0.15 to 1.07) improved children's attitudes; there was no evidence for parasocial contact (d = 0.20, 95% CI -0.01 to 1.40). CONCLUSIONS: Direct, extended, and guided imagined contact interventions are effective in improving children's attitudes towards disability; there was no evidence for parasocial contact.We acknowledge funding from the National Institute for Health Research (NIHR) Collaboration for Leadership in Applied Health Research and Care of the South West Peninsula (PenCLAHRC), and the charity Cerebra

Extent of regretted sexual intercourse among young teenagers in Scotland: a cross sectional survey

No abstract available