3,785 research outputs found
Development of a theory of the spectral reflectance of minerals, part 2
Theory of diffuse reflectance of particulate media including garnet, glass, corundum powders, and mixture
Collimated, single-pass atom source from a pulsed alkali metal dispenser for laser-cooling experiments
We have developed an improved scheme for loading atoms into a magneto-optical
trap (MOT) from a directed alkali metal dispenser in < 10^-10 torr ultra-high
vacuum conditions. A current-driven dispenser was surrounded with a cold
absorbing "shroud" held at < 0 C, pumping rubidium atoms not directed into the
MOT. This nearly eliminates background alkali atoms and reduces the detrimental
rise in pressure normally associated with these devices. The system can be
well-described as a current-controlled, rapidly-switched, two-temperature
thermal beam, and was used to load a MOT with 3 x 10^8 atoms.Comment: 5 pages, 4 figure
The self-consistent gravitational self-force
I review the problem of motion for small bodies in General Relativity, with
an emphasis on developing a self-consistent treatment of the gravitational
self-force. An analysis of the various derivations extant in the literature
leads me to formulate an asymptotic expansion in which the metric is expanded
while a representative worldline is held fixed; I discuss the utility of this
expansion for both exact point particles and asymptotically small bodies,
contrasting it with a regular expansion in which both the metric and the
worldline are expanded. Based on these preliminary analyses, I present a
general method of deriving self-consistent equations of motion for arbitrarily
structured (sufficiently compact) small bodies. My method utilizes two
expansions: an inner expansion that keeps the size of the body fixed, and an
outer expansion that lets the body shrink while holding its worldline fixed. By
imposing the Lorenz gauge, I express the global solution to the Einstein
equation in the outer expansion in terms of an integral over a worldtube of
small radius surrounding the body. Appropriate boundary data on the tube are
determined from a local-in-space expansion in a buffer region where both the
inner and outer expansions are valid. This buffer-region expansion also results
in an expression for the self-force in terms of irreducible pieces of the
metric perturbation on the worldline. Based on the global solution, these
pieces of the perturbation can be written in terms of a tail integral over the
body's past history. This approach can be applied at any order to obtain a
self-consistent approximation that is valid on long timescales, both near and
far from the small body. I conclude by discussing possible extensions of my
method and comparing it to alternative approaches.Comment: 44 pages, 4 figure
Charge dependence of neoclassical and turbulent transport of light impurities on MAST
Carbon and nitrogen impurity transport coefficients are determined from gas
puff experiments carried out during repeat L-mode discharges on the Mega-Amp
Spherical Tokamak (MAST) and compared against a previous analysis of helium
impurity transport on MAST. The impurity density profiles are measured on the
low-field side of the plasma, therefore this paper focuses on light impurities
where the impact of poloidal asymmetries on impurity transport is predicted to
be negligible. A weak screening of carbon and nitrogen is found in the plasma
core, whereas the helium density profile is peaked over the entire plasma
radius.Comment: 17 pages, 7 figure
Psychotherapy mediated by remote communication technologies: a meta-analytic review
Reproduced with permission of the publisher. © 2008 Bee et al; licensee BioMed Central Ltd. The electronic version of this article is the complete one and can be found online at: http://www.biomedcentral.com/1471-244X/8/60. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Background
Access to psychotherapy is limited by psychopathology (e.g. agoraphobia), physical disability, occupational or social constraints and/or residency in under-served areas. For these populations, interventions delivered via remote communication technologies (e.g. telephone, internet) may be more appropriate. However, there are concerns that such delivery may influence the therapeutic relationship and thus reduce therapy effectiveness. This review aimed to determine the clinical effectiveness of remotely communicated, therapist-delivered psychotherapy.
Methods
Systematic review (including electronic database searching and correspondence with authors) of randomised trials of individual remote psychotherapy. Electronic databases searched included MEDLINE (1966–2006), PsycInfo (1967–2006), EMBASE (1980–2006) and CINAHL databases (1982–2006). The Cochrane Central Register of Controlled Trials (CENTRAL) and the Cochrane Collaboration Depression, Anxiety and Neurosis Controlled Trials Register (CCDAN-CTR). All searches were conducted to include studies with a publication date to July 2006.
Results
Thirteen studies were identified, ten assessing psychotherapy by telephone, two by internet and one by videoconference. Pooled effect sizes for remote therapy versus control conditions were 0.44 for depression (95%CI 0.29 to 0.59, 7 comparisons, n = 726) and 1.15 for anxiety-related disorders (95%CI 0.81 to 1.49, 3 comparisons, n = 168). There were few comparisons of remote versus face-to-face psychotherapy.
Conclusion
Remote therapy has the potential to overcome some of the barriers to conventional psychological therapy services. Telephone-based interventions are a particularly popular research focus and as a means of therapeutic communication may confer specific advantages in terms of their widespread availability and ease of operation. However, the available evidence is limited in quantity and quality. More rigorous trials are required to confirm these preliminary estimates of effectiveness. Future research priorities should include overcoming the methodological shortcomings of published work by conducting large-scale trials that incorporate both clinical outcome and more process-orientated measures
The Relationships between Human Fatigue and Public Health: A Brief Commentary on Selected Papers from the 9th International Conference on Managing Fatigue in Transportation, Resources and Health
The 9th International Conference on Managing Fatigue in Transportation, Resources and Health was held in Fremantle, Western Australia in March 2015. The purpose of the conferences in this series is to provide a forum for industry representatives, regulators, and scientists to discuss recent advances in the field of fatigue research. We have produced a Special Issue of the International Journal of Environmental Research and Public Health based on papers from the conference that were focused on various aspects of public health. First, the Special Issue highlights the fact that working long shifts and/or night shifts can affect not only cognitive functioning, but also physical health. In particular, three papers examined the potential relationships between shiftwork and different aspects of health, including the cardiovascular system, sleep disordered breathing, and eating behaviour. Second, the Special Issue highlights the move away from controlling fatigue through prescriptive hours of service rules and toward the application of risk management principles. In particular, three papers indicated that best-practice fatigue risk management systems should contain multiple redundant layers of defense against fatigue-related errors and accidents
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Rhythm in the speech of a person with right hemisphere damage: Applying the pairwise variability index
Although several aspects of prosody have been studied in speakers with right hemisphere damage (RHD), rhythm remains largely uninvestigated. This study compares the rhythm of an Australian English speaker with right hemisphere damage (due to a stroke, but with no concomitant dysarthria) to that of a neurologically unimpaired individual. The speakers' rhythm is compared using the pairwise variability index (PVI) which allows for an acoustic characterization of rhythm by comparing the duration of successive vocalic and intervocalic intervals. A sample of speech from a structured interview between a speech and language therapist and each participant was analysed. Previous research has shown that speakers with RHD may have difficulties with intonation production, and therefore it was hypothesized that there may also be rhythmic disturbance. Results show that the neurologically normal control uses a similar rhythm to that reported for British English (there are no previous studies available for Australian English), whilst the speaker with RHD produces speech with a less strongly stress-timed rhythm. This finding was statistically significant for the intervocalic intervals measured (t(8) = 4.7, p < .01), and suggests that some aspects of prosody may be right lateralized for this speaker. The findings are discussed in relation to previous findings of dysprosody in RHD populations, and in relation to syllable-timed speech of people with other neurological conditions
The effects of dietary fish oil on hepatic high density and low density lipoprotein receptor activities in the rat
AbstractRats were fed either a standard ration diet or that diet supplemented with 8% by wt of a marine fish oil or safflower oil. After 10 days, plasma triacylglycerols, total cholesterol, high density lipoprotein (HDL) cholesterol, hepatic cholesterol and fatty acid synthesis and hepatic low density lipoprotein (LDL) receptor activity were significantly depressed while HDL receptor activity was significantly increased in rats fed fish oil. Fish oil-induced effects on cholesterol metabolism in the rat therefore include reciprocal changes in the activities of hepatic LDL and HDL receptors
Composition, Morphology, and Stratigraphy of Noachian Crust around the Isidis basin
Definitive exposures of pristine, ancient crust on Mars are rare, and the finding that much of the ancient Noachian terrain on Mars exhibits evidence of phyllosilicate alteration adds further complexity. We have analyzed high-resolution data from the Mars Reconnaissance Orbiter in the well-exposed Noachian crust surrounding the Isidis basin. We focus on data from the Compact Reconnaissance Imaging Spectrometer for Mars as well as imaging data sets from High Resolution Imagine Science Experiment and Context Imager. These data show the lowermost unit of Noachian crust in this region is a complex, brecciated unit of diverse compositions. Breccia blocks consisting of unaltered mafic rocks together with rocks showing signatures of Fe/Mg-phyllosilicates are commonly observed. In regions of good exposure, layered or banded phyllosilicate-bearing breccia rocks are observed suggestive of pre-Isidis sedimentary deposits. In places, the phyllosilicate-bearing material appears as a matrix surrounding mafic blocks, and the mafic rocks show evidence of complex folded relationships possibly formed in the turbulent flow during emplacement of basin-scale ejecta. These materials likely include both pre-Isidis basement rocks as well as the brecciated products of the Isidis basin–forming event at 3.9 Ga. A banded olivine unit capped by a mafic unit covers a large topographic and geographic range from northwest of Nili Fossae to the southern edge of the Isidis basin. This olivine-mafic cap combination superimposes the phyllosilicate-bearing basement rocks and distinctly conforms to the underlying basement topography. This may be due to draping of the topography by a fluid or tectonic deformation of a previously flatter lying morphology. We interpret the draping, superposed olivine-mafic cap combination to be impact melt from the Isidis basin–forming event. While some distinct post-Isidis alteration is evident (carbonate, kaolinite, and serpentine), the persistence of olivine from the time of Isidis basin suggests that large-scale aqueous alteration processes had ceased by the time this unit was emplaced
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Deciphering the mechanisms of phonological therapy in jargon aphasia
Background: Severe word production difficulties remain one of the most challenging clinical symptoms to treat in individuals with jargon aphasia. Clinically, it is important to determine why some individuals with jargon aphasia improve following therapy when others do not. We report a therapy study with AM, an individual with severe neologistic jargon aphasia, and provide a subsequent comparison to previous cases, with the purpose of informing both our theoretical and clinical understanding of jargon aphasia.
Aims: This research aimed to investigate AM’s locus of word production deficit and determine the effectiveness of Phonological Component Analysis (PCA) therapy, a phonological cueing therapy, in the re-learning and generalization of naming responses for words. In addition, AM’s performance in therapy, linguistic profile, and ability to engage with therapy/cues were compared in a retrospective analysis with the background linguistic and therapy data of two other individuals with jargon aphasia (P9, Leonard et al., 2008; FF, Bose, 2013), who responded differentially to PCA. This was undertake to explore possible prognostic indicators of phonological therapy for jargon aphasia.
Methods and Procedures: A battery of linguistic and neuropsychological tests was used to identify AM’s word production deficit. A single-subject multiple probe design across behaviours was employed to evaluate the effects of PCA therapy on the re-learning and generalization of naming responses. In the retrospective analysis of AM, P9 and FF, we compared differences and similarities in performance on various linguistic tasks, the ability to engage in therapy (i.e., ability to generate and utilize the cues), as well as to retain and maintain cues.
Outcomes and Results: AM’s locus of deficit was identified in the mapping between semantics and phonology. PCA was found to be effective in improving naming in two of the three treated word lists during the treatment phase; however, these gains were not maintained. Generalization to untreated picture names was not observed. Findings from the retrospective analysis illustrated that oral reading skills, ability to segment phonological information from words and active engagement with provided cues are likely prerequisites for obtaining robust and long-term gains.
Conclusions and Implications: We demonstrated that phonological therapy could be beneficial for the remediation of naming abilities at least in the re-learning phase; however, maintenance and generalization of these gains were limited. This research helps to elucidate the considerations and evaluations necessary for the appropriateness of phonological therapy and candidacy of individuals with jargon aphasia for this treatment approach
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