25,541 research outputs found
Polarized Scattering in the Vicinty of Galaxies
Some bright cD galaxies in cluster cooling flows have Thomson optical depths
exceeding 0.01. A few percent of their luminosity is scattered and appears as
diffuse polarized emission. We calculate the scattering process for different
geometric combinations of luminosity sources and scattering media. We apply our
results to galaxies, with and without active nuclei, immersed in cooling flows.
We model observations of NGC 1275 and M87 (without active nuclei) in the
presence of sky and galactic background fluxes which hinder the measurement of
the scattered light at optical wavelengths. Current instruments are unable to
detect the scattered light from such objects. However, when a galaxy has an
active nucleus of roughly the same luminosity as the remainder of the galaxy in
V, both the total and polarized scattered intensity should observable on large
scales (5--30kpc), meaning intensity levels greater than 1% of the background
level. For typical AGN and galaxy spectral distributions, the scattering is
most easily detected at short (U) wavelengths. We point out that a number of
such cases will occur. We show that the radiation pattern from the central
nuclear region can be mapped using the scattering. We also show that the
scattered light can be used to measure inhomogeneities in the cooling flow.Comment: 29 pages of TEX, 14 figs, CRSR-1046, in ApJ Nov 20, 199
Seeing is believing: an interpretative phenomenological analysis of the experiences of the ‘spiritual but not religious’ in Britain
A majority of the British population now consider themselves not religious, but many of these individuals still have some beliefs they consider spiritual. This study explores the connections between the beliefs and practices of five British participants who identified as ‘spiritual but not religious’ (SBNR). Semi-structured interviews with each participant were analyzed inductively using interpretative phenomenological analysis (IPA). This analysis developed seven sub-themes that were organized into two superordinate themes: ‘Experiencing Transcendence’ and ‘Constructing a Personal Spirituality’. The participants’ spirituality was an important part of their identities and lives. They pragmatically and eclectically drew on a wide range of spiritual tools and resources to enrich their lives. In a complex world where they considered traditional sources of religious or spiritual authority untrustworthy, the participants developed their own answers to existential questions that resonated with their own experiences of the world. Both their personal experiences and sociocultural influences were important in shaping and sustaining the participants’ worldviews and practices. These idiosyncratic ways that individuals made sense of their experiences show why it is important the research tools used to study worldview dynamics are sensitive to a wide range of factors and the iterative interactions between them
‘I believe in something; I don’t know what it is’: an exploration of five British Hindus’ worldviews using interpretative phenomenological analysis
Previous research has suggested individuals can draw on resources from a diverserange of existential cultures when constructing their personal worldviews. However, the ways individuals’ beliefs and worldviews are acquired and develop is still onlypartially understood. This study investigates these processes of worldview dynamicsby exploring the beliefs and practices of five British Hindus. Semi-structured interviews with each participant were inductively analyzed using interpretative phenomenological analysis (IPA). This analysis developed six sub-themes which formed two superordinate themes: ‘Everybody has their own way’ and ‘Focusing on this world’. The analysis shows the complexity of many individuals’ worldviews and demonstrates how individuals can live in a hinterland between religiosity and non-religiosity. For these participants, existential beliefs were idiosyncratic and deeply personal. They rejected some aspects of their cultural heritage while retaining others. The participants were comfortable with uncertainty about such matters and were highly tolerant of divergent beliefs. Understanding how these participants made sense of their world increases our understanding of both worldview dynamics and the forms that secularity can take in modern Britain. This shows why more nuanced understandings of ‘belief’ are necessary to explore the complexity of people’s lived experiences
The Gravitomagnetic Influence on Gyroscopes and on the Lunar Orbit
Gravitomagnetism--a motional coupling of matter analogous to the Lorentz
force in electromagnetism--has observable consequences for any scenario
involving differing mass currents. Examples include gyroscopes located near a
rotating massive body, and the interaction of two orbiting bodies. In the
former case, the resulting precession of the gyroscope is often called ``frame
dragging,'' and is the principal measurement sought by the Gravity Probe-B
experiment. The latter case is realized in the earth-moon system, and the
effect has in fact been confirmed via lunar laser ranging (LLR) to
approximately 0.1% accuracy--better than the anticipated accuracy of the
Gravity-Probe-B result. This paper shows the connnection between these
seemingly disparate phenomena by employing the same gravitomagnetic term in the
equation of motion to obtain both gyroscopic precession and modification of the
lunar orbit. Since lunar ranging currently provides a part in a thousand fit to
the gravitomagnetic contributions to the lunar orbit, this feature of
post-Newtonian gravity is not adjustable to fit any anomalous result beyond the
0.1% level from Gravity Probe-B without disturbing the existing fit of theory
to the 36 years of LLR data.Comment: 4 pages; accepted for publication in Physical Review Letter
Fifteen-foot diameter modular space station Kennedy Space Center launch site support definition (space station program Phase B extension definition)
This document defines the facilities, equipment, and operational plans required to support the MSS Program at KSC. Included is an analysis of KSC operations, a definition of flow plans, facility utilization and modifications, test plans and concepts, activation, and tradeoff studies. Existing GSE and facilities that have a potential utilization are identified, and new items are defined where possible. The study concludes that the existing facilities are suitable for use in the space station program without major modification from the Saturn-Apollo configuration
Multiparameter Ultrasonic Evaluation of Ceramic Matrix Composites
Quantitative multiparameter ultrasonic methods are under development for the evaluation of composite materials. Dual frequency, throughtransmission, tone burst signals are used to provide calibrated attenuation data and the frequency dependence thereof. Pulse-echo, spike pulse signals are used to obtain depth information for internal reflectors. Monostatic and bistatic backscatter and bistatic forwardscatter techniques are also used to increase sensitivity to small flaws. Example results are presented for silicon carbide (SiC) fiber reinforced lithium alumino silicate (LAS) glass-ceramic matrix composites. Results include those for manufactured and naturally occurring flaws
Targeting the Microbiota to Address Diet-Induced Obesity: A Time Dependent Challenge
peer-reviewedLinks between the gut microbiota and host metabolism have provided new perspectives on obesity. We previously showed that the link between the microbiota and fat deposition is age- and time-dependent subject to microbial adaptation to diet over time. We also demonstrated reduced weight gain in diet-induced obese (DIO) mice through manipulation of the gut microbiota with vancomycin or with the bacteriocin-producing probiotic Lactobacillus salivarius UCC118 (Bac+), with metabolic improvement achieved in DIO mice in receipt of vancomycin. However, two phases of weight gain were observed with effects most marked early in the intervention phase. Here, we compare the gut microbial populations at the early relative to the late stages of intervention using a high throughput sequencing-based analysis to understand the temporal relationship between the gut microbiota and obesity. This reveals several differences in microbiota composition over the intervening period. Vancomycin dramatically altered the gut microbiota composition, relative to controls, at the early stages of intervention after which time some recovery was evident. It was also revealed that Bac+ treatment initially resulted in the presence of significantly higher proportions of Peptococcaceae and significantly lower proportions of Rikenellaceae and Porphyromonadaceae relative to the gut microbiota of L. salivarius UCC118 bacteriocin negative (Bac-) administered controls. These differences were no longer evident at the later time. The results highlight the resilience of the gut microbiota and suggest that interventions may need to be monitored and continually adjusted to ensure sustained modification of the gut microbiota.The authors are supported in part by Teagasc, Science Foundation Ireland (in the form of a research centre grant to the Alimentary Pharmabiotic Centre and PI awards to PWOT and PC) and by Alimentary Health Ltd
Timing by Stellar Pulsations as an Exoplanet Discovery Method
The stable oscillations of pulsating stars can serve as accurate timepieces,
which may be monitored for the influence of exoplanets. An external companion
gravitationally tugs the host star, causing periodic changes in pulsation
arrival times. This method is most sensitive to detecting substellar companions
around the hottest pulsating stars, especially compact remnants like white
dwarfs and hot subdwarfs, as well as delta Scuti variables (A stars). However,
it is applicable to any pulsating star with sufficiently stable oscillations.
Care must be taken to ensure that the changes in pulsation arrival times are
not caused by intrinsic stellar variability; an external, light-travel-time
effect from an exoplanet identically affects all pulsation modes. With more
long-baseline photometric campaigns coming online, this method is yielding new
detections of substellar companions.Comment: 9 pages, 2 figures: Invited review to appear in 'Handbook of
Exoplanets,' Springer Reference Works, edited by Hans J. Deeg and Juan
Antonio Belmont
Properties of HxTaS2
The preparation of Hx TaS2 (0 \u3c x \u3c 0.87) is described. The compounds are only marginally stable at room temperature, slowly evolving H2S and H2 (and possibly Hp in air). Magnetic susceptibility data show that a low temperature transformation in 2H ... TaS2 (at so•K) is suppressed with the addition of hydrogen, and· at the same time the superconducting transition temperature T c rises from 0.8 to ~4.2•K at x = 0.11. Heat capacity measurements near this concentration show the superconductivity to be a bulk effect. Finally, by correlation of this data with susceptibility and T c measurements in other intercalation compounds, we suggest that the rise of T c (at low electron transfer) is due to suppression of the low temperature transformation and not due to an excitonic mechanism of superconductivity
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