Energy-resolved electron-spin dynamics at surfaces of p-doped GaAs

Electron-spin relaxation at different surfaces of p-doped GaAs is investigated by means of spin, time and energy resolved 2-photon photoemission. These results are contrasted with bulk results obtained by time-resolved Faraday rotation measurements as well as calculations of the Bir-Aronov-Pikus spin-flip mechanism. Due to the reduced hole density in the band bending region at the (100) surface the spin-relaxation time increases over two orders of magnitude towards lower energies. At the flat-band (011) surface a constant spin relaxation time in agreement with our measurements and calculations for bulk GaAs is obtained.Comment: 6 pages, 4 figure

Vocational perspectives after spinal cord injury

Objective: To give insight into the vocational situation several years after a traumatic spinal cord injury (SCI) and describe the personal experiences and unmet needs; to give an overview of health and functional status per type of SCI and their relationship with employment status. Design: Descriptive analysis of data from a questionnaire. Setting: Dutch rehabilitation centre with special department for patients with spinal cord injuries. Subjects: Fifty-seven patients with a traumatic SCI, aged 18-60 years, admitted to the rehabilitation centre from 1990 to 1998. Main measures: Questionnaire with items related to vocational outcome, job experiences, health and functional status. Results: Of 49 patients who were working at the moment of SCI 60% currently had a paid job. Vocational outcome was related to a higher educational level. A significant relation between the SCI-specific health and functional status and employment was not found. The respondents who changed to a new employer needed more time to resume work, but seemed more satisfied with the job and lost fewer working hours than those who resumed work with the same employer. In spite of reasonable to good satisfaction with the current work situation, several negative experiences and unmet needs were reported. Conclusions: Despite a high participation in paid work following SCI, the effort of the disabled worker to have and keep a job should not be underestimated

Material and Seismic Assessment of the Great House at Casa Grande Ruins National Monument, Arizona

The authors characterized earthen wall materials and plasters in a mid-fourteenth-century Hohokam great house at Casa Grande Ruins National Monument (Arizona) and assessed the seismic susceptibility of its puddled earth walls. Characterization included determining the microstructure, microcomposition, porosity, aggregate mineralogy, and identification of phases in the binding matrix for each of 36 samples and reconstructing plaster technologies, including material selection, preparation, and application sequences. Findings support the ideas that earthen materials were manipulated to optimize their performance to suit the unique site conditions and needs of the ancient people using the structure and included finishes that were unusual in southwestern sites from this time period. By using a new set of tools that integrate the complicated geometry of individual wall segments as captured in light detection and ranging (LiDAR) scans (models were generated in Rhino version 5) with the dynamic analysis of rocking mechanisms (tools for this analysis were developed in Rhino), seismic collapse assessment was used to identify the most vulnerable parts of the building to earthquake loading and provided an initial evaluation of the seismic overturning capacity of these wall segments

Earth imaging results from Galileo's second encounter

The recent flyby of the Galileo spacecraft en route to Jupiter contributes a unique perspective to our view of our home planet. Imaging activities conducted during the second Earth encounter provide an important opportunity to assess new methods and approaches on familiar territory. These include unique multispectral observations, low light-level imaging (searches for aurorae, lightning and artificial lights on the nightside) and experiments with multiple exposure times to extend the effective radiometric resolution and dynamic range of the camera system. Galileo imaging data has the potential to make important contributions to terrestrial remote sensing. This is because the particular set of filters included in the Solid State Imaging system are not presently incorporated in any currently operating Earth-orbiting sensor system. The visible/near-infrared bandpasses of the SSI filters are well suited to remote sensing of geological, glaciological, botanical, and meteorological phenomena. Data from this and the previous Earth encounter may provide an extremely valuable reference point in time for comparison with similar data expected from EOS or other systems in the future, contributing directly to our knowledge of global change. The highest resolution imaging (0.2 km/pixel) during the December, 1992 encounter occurred over the central Andes; a five filter mosaic of visible and near infrared bands displays the remarkable spectral heterogeneity of this geologically diverse region. As Galileo departed the Earth, cooperative imaging with the Near Infrared Mapping Spectrometer (NIMS) instrument targeted Antarctica, Australia, and Indonesia at 1.0 to 2.5 km/pixel resolutions in the early morning local times near the terminator. The Antarctic data are of particular interest, potentially allowing ice grain size mapping using the 889 and 968 nm filters and providing an important means of calibrating the technique for application to the Galilean satellites. As the spacecraft receded further, regional scale imaging provided data which, along with data from the previous encounter, will enable the production of global multispectral mosaics of Earth in each of the SSI filters

Nodular Regenerative Hyperplasia Secondary to Neoadjuvant Chemotherapy for Colorectal Liver Metastases

Liver resection is the only curative treatment for patients with colorectal liver metastases (CLMs). Neoadjuvant chemotherapy can improve resectability but has a potential harmful effect on the nontumorous liver. Patients with chemotherapy-induced hepatic injury undergoing liver surgery have higher risks of post-resectional morbidity. We present two cases of patients without pre-existent liver disease treated with oxaliplatin-based chemotherapy followed by surgical resection of their CLMs. Their intra-operative liver specimen showed morphologic abnormalities characteristic of nodular regenerative hyperplasia (NRH). NRH led to portal hypertension in both patients that resulted in deleterious post-resectional complications and death of one patient. Interestingly, the other patient underwent two repeat nonanatomic liver resections because of recurrent CLMs. The intra-operative liver specimen still showed signs of NRH and sinusoidal congestion, but the post-resectional courses were uneventful. Nevertheless, caution is recommended in patients with suspected NRH. Careful volumetric analysis should guide the operative strategy. When future remnant liver volume is regarded insufficient, portal vein embolization or restrictive surgery should be considered

Imaging beta-adrenoceptors in the human brain with (S)-1'-[F-18]fluorocarazolol

We evaluated the suitability of fluorocarazolol for in vivo studies of cerebral beta-adrenoceptors because (S)-1'-[F-18]fluorocarazolol has a higher affinity to beta-adrenoceptors than to serotonergic receptors (pK(i) beta(1) 9.4, beta(2) 10.0, 5HT(1A) 7.4, 5HT(1B) 8.1) and rapidly crosses the blood-brain barrier. Methods: The (S)-[F-18]fluorocarazolol (74 MBq, >37 TBq/mmol) was intravenously administered to healthy volunteers on two separate occasions with an interval of at least 1 wk, The initial injection was without pretreatment, but before the second injection, the volunteers received the beta blocker (+/-)-pindolol (3 x 5 mg orally, during 18 hr). The brain was studied with a PET camera in dynamic mode. Results: Uptake of radioactivity delineated gray matter and was particularly high in the posterior cingulate, precuneus and striatum, Low uptake occurred in the thalamus, whereas the lowest uptake was observed in the white matter of the corpus callosum. After pindolol pretreatment, uptake was reduced and its distribution became homogeneous throughout the brain, The ratio of total-to-nonspecific binding was about 2 at 60 min, increasing to 2.5-2.75 at longer intervals. Conclusion: Fluorocarazolol is the first radioligand that can visualize cerebral beta-adrenoceptors and may enable monitoring of these binding sites during disease

Imaging beta-adrenoceptors in the human brain with (S)-1'-[F-18]fluorocarazolol

We evaluated the suitability of fluorocarazolol for in vivo studies of cerebral beta-adrenoceptors because (S)-1'-[F-18]fluorocarazolol has a higher affinity to beta-adrenoceptors than to serotonergic receptors (pK(i) beta(1) 9.4, beta(2) 10.0, 5HT(1A) 7.4, 5HT(1B) 8.1) and rapidly crosses the blood-brain barrier. Methods: The (S)-[F-18]fluorocarazolol (74 MBq, >37 TBq/mmol) was intravenously administered to healthy volunteers on two separate occasions with an interval of at least 1 wk, The initial injection was without pretreatment, but before the second injection, the volunteers received the beta blocker (+/-)-pindolol (3 x 5 mg orally, during 18 hr). The brain was studied with a PET camera in dynamic mode. Results: Uptake of radioactivity delineated gray matter and was particularly high in the posterior cingulate, precuneus and striatum, Low uptake occurred in the thalamus, whereas the lowest uptake was observed in the white matter of the corpus callosum. After pindolol pretreatment, uptake was reduced and its distribution became homogeneous throughout the brain, The ratio of total-to-nonspecific binding was about 2 at 60 min, increasing to 2.5-2.75 at longer intervals. Conclusion: Fluorocarazolol is the first radioligand that can visualize cerebral beta-adrenoceptors and may enable monitoring of these binding sites during disease

An exploratory cluster randomised trial of a university halls of residence based social norms marketing campaign to reduce alcohol consumption among 1st year students

<p>Aims: This exploratory trial examines the feasibility of implementing a social norms marketing campaign to reduce student drinking in universities in Wales, and evaluating it using cluster randomised trial methodology.</p> <p>Methods: Fifty residence halls in 4 universities in Wales were randomly assigned to intervention or control arms. Web and paper surveys were distributed to students within these halls (n = 3800), assessing exposure/contamination, recall of and evaluative responses to intervention messages, perceived drinking norms and personal drinking behaviour. Measures included the Drinking Norms Rating Form, the Daily Drinking Questionnaire and AUDIT-C.</p> <p>Results: A response rate of 15% (n = 554) was achieved, varying substantially between sites. Intervention posters were seen by 80% and 43% of students in intervention and control halls respectively, with most remaining materials seen by a minority in both groups. Intervention messages were rated as credible and relevant by little more than half of students, though fewer felt they would influence their behaviour, with lighter drinkers more likely to perceive messages as credible. No differences in perceived norms were observed between intervention and control groups. Students reporting having seen intervention materials reported lower descriptive and injunctive norms than those who did not.</p> <p>Conclusions: Attention is needed to enhancing exposure, credibility and perceived relevance of intervention messages, particularly among heavier drinkers, before definitive evaluation can be recommended. A definitive evaluation would need to consider how it would achieve sufficient response rates, whilst hall-level cluster randomisation appears subject to a significant degree of contamination.</p&gt