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The effect of providing a shelter to single-housed rats was measured in terms of the preference shown for a cage containing a shelter compared with a barren cage, the range of behaviours performed and the apparent fearfulness of the animals. All animals showed a strong preference for cages containing a shelter and rats housed in this environment showed increased exploratory behaviour and were apparently less fearful, based on their willingness to leave the home-cage. It would seem appropriate to provide enclosed shelters within the cages of laboratory rats as a way of improving their environment.
This chapter sets out experimental evidence for lasting effects of maternal and paternal exposures during critical windows of development around the time of conception, and points to the increasing evidence supporting adolescence and preconception as critical windows for the health of the next generation. This is set in the context of sections providing overviews of pregnancy and lactation, prematurity and infancy as more established critical windows during which environmental exposures can have lasting consequences for health and the risk of disease. Conceptually, these represent periods when timely interventions are considered to have the greatest potential for enhancing the development of functional capacity, thereby promoting resilience throughout the life-course.
Thermoluminescence (TL) studies of insulators, including crystals of minerals such as calcite, quartz or zircon, have resulted in the development of a wider range of applications in the fields of radiation dosimetry and archaeological and geological dating. Most conventional TL measurements are made by recording light emission during heating by means of broad-band optical filters and blue-sensitive photomultiplier tubes. Much more information may be gained by monitoring the details of the emission spectrum during thermoluminescence. TL spectra of minerals exhibit changes as a result of crystal purity, radiation dose, dose rate and thermal history. This paper exemplifies the additional information available as a result of spectral studies, and focuses on investigations undertaken by the University of Sussex TL group. Examples include work on calcite, fluorite, zircon and feldspars.
Cathodoluminescence (CL) provides a sensitive analytical probe of the near-surface region of insulating materials, and some new examples of the strengths of the technique are presented using recent data from the University of Sussex. Analysis of float glass shows that by spectral and lifetime resolved data it is possible to separate the emission bands from excitonic, intrinsic imperfections, and impurities in various valence states, as a function of their depth beneath the surface. Correlation of the CL data with those from Mössbauer, ion beam and other analyses then provides the basis for models of the defect sites. CL from a second glass, ZBLAN, reveals the presence of microcrystallites and growth defects, and the work underpins confidence in the high purity gas levitation method of ZBLAN production. New results on CL of wavelength shifts with crystal field of Mn in carbonates are presented, and of Nd emission from Nd:YAG. The effects are directly linked to surface damage and dislocations caused by sample preparation steps of cutting and polishing. Methods to minimise the damage, by furnace or pulsed laser annealing, and chemical routes, are mentioned. Such surface preparation damage has a profound effect on all CL monitoring, whether for fundamental studies or mineralogical applications. Finally, a route to eliminate such problems is demonstrated, with consequent improvements in luminescence, transmission and laser performance of surface waveguides. The implications of improved surface quality range widely from mineralogical CL imaging through improved photonic materials and epitaxial growth to elimination of surface damage, and additional information.
This contribution gave three examples of X-ray transients in the Magellanic Clouds and the Milky Way that have been observed as part of the SALT Transients Large Programme. The transients (SMC X-3, MAXI J1957+032 and ASASSN-16oh) have been triggered from both space-based wide-field monitoring facilities (Swift/XRT, MAXI) and ground-based ones (ASASSN, the All Sky Automated Survey for SN), providing insights into the physics of super-Eddington accretion onto neutron stars and white dwarfs, and also into the long-term properties of accreting millisecond X-ray pulsars.
Background: Approximately 12-15% of patients with intracranial aneurysms (IA) have affected first-degree relatives, and are considered to have familial intracranial aneurysms (FIA). Individuals with FIA are at higher risk for aneurysm formation and subarachnoid hemorrhage. THSD1 is the only gene to be associated with nonsyndromic FIA at this time. Our study aims to find rare DNA variants that are major risk factors for FIA in our cohort of patients. Methods: To date we have enrolled 37 affected and 31 unaffected people from 16 families. We have done exome or genome sequencing on at least 1 person from each of 12 families. Results: A rare p.(R686W) variant in THSD1 was found in 1/12 families, but did not cosegregate fully with disease. While less attractive as the primary cause of FIA, we cannot rule out the potential modifying effects of THSD1 p.(R686W) in this family. A second candidate, an extracellular matrix gene within a chromosomal region previously implicated by familial mapping studies, contains rare variants in 4/12 of our families. All four variants are predicted to be damaging. Conclusions: Alongside environmental risk factors, individual FIA families may also have complex rare variant contributions to their disease, such as digenic and multi-locus contributions.
Recent spectropolarimetric surveys of bright, hot stars have found that ~10% of OB-type stars contain strong (mostly dipolar) surface magnetic fields (~kG). The prominent paradigm describing the interaction between the stellar winds and the surface magnetic field is the magnetically confined wind shock (MCWS) model. In this model, the stellar wind plasma is forced to move along the closed field loops of the magnetic field, colliding at the magnetic equator, and creating a shock. As the shocked material cools radiatively it will emit X-rays. Therefore, X-ray spectroscopy is a key tool in detecting and characterizing the hot wind material confined by the magnetic fields of these stars. Some B-type stars are found to have very short rotational periods. The effects of the rapid rotation on the X-ray production within the magnetosphere have yet to be explored in detail. The added centrifugal force due to rapid rotation is predicted to cause faster wind outflows along the field lines, leading to higher shock temperatures and harder X-rays. However, this is not observed in all rapidly rotating magnetic B-type stars. In order to address this from a theoretical point of view, we use the X-ray Analytical Dynamical Magnetosphere (XADM) model, originally developed for slow rotators, with an implementation of new rapid rotational physics. Using X-ray spectroscopy from ESA’s XMM-Newton space telescope, we observed 5 rapidly rotating B-types stars to add to the previous list of observations. Comparing the observed X-ray luminosity and hardness ratio to that predicted by the XADM allows us to determine the role the added centrifugal force plays in the magnetospheric X-ray emission of these stars.
Two methods were used to estimate the cost of forward contracting hard red winter wheat. One hundred days before delivery, the estimated cost of forward contracting ranged from six cents/bu. to eight cents/bu. Thus, further evidence is provided that the cost of forward contracting grain is not zero.
Chagas disease is an important emerging disease in Texas that results in cardiomyopathy in about 30% of those infected with the parasite Trypanosoma cruzi. Between the years 2008 and 2012, about 1/6500 blood donors were T. cruzi antibody-confirmed positive. We found older persons and minority populations, particularly Hispanic, at highest risk for screening positive for T. cruzi antibodies during routine blood donation. Zip code analysis determined that T. cruzi is associated with poverty. Chagas disease has a significant disease burden and is a cause of substantial economic losses in Texas.
A subpopulation (~10%) of hot, luminous, massive stars have been revealed through spectropolarimetry to harbor strong (hundreds to tens of thousand Gauss), steady, large-scale (often significantly dipolar) magnetic fields. This review focuses on the role of such fields in channeling and trapping the radiatively driven wind of massive stars, including both in the strongly perturbed outflow from open field regions, and the wind-fed “magnetospheres” that develop from closed magnetic loops. For B-type stars with weak winds and moderately fast rotation, one finds “centrifugal magnetospheres”, in which rotational support allows magnetically trapped wind to accumulate to a large density, with quite distinctive observational signatures, e.g. in Balmer line emission. In contrast, more luminous O-type stars have generally been spun down by magnetic braking from angular momentum loss in their much stronger winds. The lack of centrifugal support means their closed loops form a “dynamical magnetosphere”, with trapped material falling back to the star on a dynamical timescale; nonetheless, the much stronger wind feeding leads to a circumstellar density that is still high enough to give substantial Balmer emission. Overall, this review describes MHD simulations and semi-analytic dynamical methods for modeling the magnetospheres, the magnetically channeled wind outflows, and the associated spin-down of these magnetic massive stars.
The magnetic activity of solar-type and low-mass stars is a well known source of coronal X-ray emission. At the other end of the main sequence, X-rays emission is instead associated with the powerful, radiatively driven winds of massive stars. Indeed, the intrinsically unstable line-driving mechanism of OB star winds gives rise to shock-heated, soft emission (~0.5 keV) distributed throughout the wind. Recently, the latest generation of spectropolarimetric instrumentation has uncovered a population of massive OB-stars hosting strong, organized magnetic fields. The magnetic characteristics of these stars are similar to the apparently fossil magnetic fields of the chemically peculiar ApBp stars. Magnetic channeling of these OB stars' strong winds leads to the formation of large-scale shock-heated magnetospheres, which can modify UV resonance lines, create complex distributions of cooled Halpha emitting material, and radiate hard (~2-5 keV) X-rays. This presentation summarizes our coordinated observational and modelling efforts to characterize the manifestation of these magnetospheres in the X-ray domain, providing an important contrast between the emission originating in shocks associated with the large-scale fossil fields of massive stars, and the X-rays associated with the activity of complex, dynamo-generated fields in lower-mass stars.
Chorion type is an important variable that can affect the prenatal environment of monozygotic (MZ) twin pairs, leading to differences in growth and development. In particular, vascular anastomoses between monochorionic (MC) MZ twin pairs can lead to an imbalance in nutrition between co-twins. One objective of this study was to determine whether maternal reports, hospital records or birthweight discordances found in MZ co-twins provide reliable indications of monochorionicity. The other objective was to test the hypotheses that in MZ twin pairs of known chorion type, MC twin pairs would show greater birthweight differences and greater within-pair variability in permanent tooth size than dichorionic (DC) twin pairs, reflecting greater differences in intrauterine environment between MC MZ pairs. Birthweights and tooth size data were recorded for 170 pairs of MZ Australian twins enrolled in an ongoing study of dentofacial growth and development. Chorion type based on maternal reports was compared with that based on hospital records for a subsample of 68 pairs of these MZ twins. Maternal reports were found to be unreliable for determining chorion type and hospital records often did not provide enough information to be certain about chorionicity. For 27 twin pairs with confirmed chorion type, associations were tested between birthweight discordances in MZ twin pairs and chorion type, and also between intrapair variances for tooth size and chorion type. A significant association was noted between birthweight discordance and chorion type (p <.05), with greater discordances occurring more often in MC twin pairs. Although significant heterogeneity of intrapair variances for tooth size was found in only 5 of 48 comparisons, intrapair variances for crown dimensions were greater significantly more often in MC pairs than DC pairs (p <.05). Our findings indicated that neither maternal reports nor often hospital records can be relied upon for information on chorion type. However, when analyses were performed on data for MZ twin pairs of known chorion type, we found evidence of a significant association between intrapair birthweight differences and chorion type and also between intrapair variances of dental crown measurements and chorion type. Consistent with our hypotheses, large birthweight discordances were found to occur more often in MC twin pairs than DC twin pairs, and intrapair variances for tooth size in MC twin pairs exceeded those in DC twin pairs more often than expected due to chance.
Impaired flexibility in the use of substrates for energy production in the heart is implicated in cardiomyopathy. We investigated the effect of maternal protein restriction during pregnancy in rats on the transcription of key genes in cardiac lipid and carbohydrate metabolism in the offspring. Rats were fed protein-sufficient or protein-restricted (PR) diets during pregnancy. Triacylglycerol concentration in adult (day 105) heart was altered by maternal protein intake contingent on post-weaning fat intake and sex. mRNA expression of peroxisomal proliferator-activated receptor (PPAR)-α and carnitine palmitoyltransferase-1 was increased by the maternal PR diet in adult, but not neonatal, offspring. PPARα promoter methylation was lower in adult and neonatal heart from PR offspring. These findings suggest that prenatal nutrition alters the future transcriptional regulation of cardiac energy metabolism in the offspring through changes in epigenetic regulation of specific genes. However, changes in gene functional changes may not be apparent in early life.
This paper presents results obtained from Stokes I and V spectra of the B2Vp star sigma Ori E, observed by both the Narval and ESPaDOnS spectropolarimeters. Using Least-Squares Deconvolution, we investigate the longitudinal magnetic field at the current epoch, including period analysis exploiting current and historical data. σ Ori E is the prototypical helium-strong star that has been shown to harbor a strong magnetic field, as well as a magnetosphere, consisting of two clouds of plasma forced by magnetic and centrifugal forces to co-rotate with the star on its 1.19 day period. The Rigidly Rotating Magnetosphere (RRM) model of Townsend & Owocki (2005) approximately reproduces the observed variations in longitudinal field strength, photometric brightness, Hα emission, and various other observables. There are, however, small discrepancies between the observations and model in the photometric light curve, which we propose arise from inhomogeneous chemical abundances on the star's surface. Using Magnetic Doppler Imaging (MDI), future work will attempt to identify the contributions to the photometric variation due to abundance spots and due to circumstellar material.
This book is the first to give a detailed description of the factors and processes which govern the optical properties of ion implanted materials, as well as an overview of the variety of devices which can be produced in this way. Beginning with an overview of the basic physics and practical methods involved in ion implantation, the topics of optical absorption and luminescence are then discussed. A chapter on waveguide analysis then provides the background for a description of particular optical devices, such as waveguide lasers, mirrors, and novel non-linear materials. The book concludes with a survey of the exciting range of potential applications. Combining both theoretical and practical aspects of the subject, the book will be invaluable to graduate students, scientists and engineers in the fields of solid state physics, quantum electronics and materials science.
We examine the angular momentum loss and associated rotational spin-down for magnetic hot stars with a line-driven stellar wind and a rotation-aligned dipole magnetic field. Our analysis here is based on our previous 2-D numerical MHD simulation study that examines the interplay among wind, field, and rotation as a function of two dimensionless parameters, W(=Vrot/Vorb) and ‘wind magnetic confinement’, η∗ defined below. We compare and contrast the 2-D, time variable angular momentum loss of this dipole model of a hot-star wind with the classical 1-D steady-state analysis by Weber and Davis (WD), who used an idealized monopole field to model the angular momentum loss in the solar wind. Despite the differences, we find that the total angular momentum loss averaged over both solid angle and time follows closely the general WD scaling ~ ṀΩR2A. The key distinction is that for a dipole field Alfvèn radius RA is significantly smaller than for the monopole field WD used in their analyses. This leads to a slower stellar spin-down for the dipole field with typical spin-down times of order 1 Myr for several known magnetic massive stars.