Respiratory challenge MRI: practical aspects

Respiratory challenge MRI is the modification of arterial oxygen (PaO2) and/or carbon dioxide (PaCO2) concentration to induce a change in cerebral function or metabolism which is then measured by MRI. Alterations in arterial gas concentrations can lead to profound changes in cerebral haemodynamics which can be studied using a variety of MRI sequences. Whilst such experiments may provide a wealth of information, conducting them can be complex and challenging. In this paper we review the rationale for respiratory challenge MRI including the effects of oxygen and carbon dioxide on the cerebral circulation. We also discuss the planning, equipment, monitoring and techniques that have been used to undertake these experiments. We finally propose some recommendations in this evolving area for conducting these experiments to enhance data quality and comparison between techniques

Herbage Characteristics as Affected by the Canopies of Dominant Trees in a Savanna of Southern Mozambique

This study surveyed the species composition, forage yield and forage nitrogen concentration of the herbaceous layer 50, 100 and 200% of the canopy radius from the trunks of many-stemmed false thorn, knob thorn, scented thorn and marula trees in a southern Mozambican savanna. Tree species did not affect herbaceous DM yield or species diversity. Neither direction nor distance from the tree trunk affected DM or specific diversity. Crude protein percentages were 15% higher for legumes and 9% higher for grasses at 50% canopy than at 200% canopy. Grasses under the marulas, the only non-legume tree in the study, had 18% lower CP than the average for the other three tree species. Green panic was the predominant grass species under the canopies while no single grass species predominated outside the canopy where common urochloa, Themeda triandra and Aristida spp. were the most common grasses. Vigna spp. and Stylosanthes fruticosa were evenly distributed whereas Tephrosia spp. was found predominantly outside the canopy

Bootstrap Technique to Study Correlation Between Neutron Skin Thickness and the Slope of Symmetry Energy in Atomic Nuclei

We examine the proposed correlation between the neutron skin thickness and the slope of the symmetry energy for two doubly-magic nuclei (Sn-100 and Sn-132) and find that a statistically significant correlation appears to exist for Sn-132 whilst no such correlation appears to exist for Sn-100. Additionally, we present a new statistical tool based on random sampling to assess the confidence interval of Pearson's and Spearman's correlation coefficients in order to examine the aforementioned correlation. These estimators are then used to quantify the statistical correlations among the neutron skin thickness of atomic nuclei and the slope of the symmetry energy in the infinite nuclear medium.Peer reviewe

Filtering wireless (Wi-Fi) internet access in public places

This paper discusses selected results from the AHRC-funded ‘Managing Access to the Internet in Public Librarie s' (MAIPLE) project and explores Wi-Fi Internet access in UK public libraries. It investigates how this compares to commercial provision of public Wi-Fi. It discusses security issues, filtering of Wi-Fi access and acceptable use policies. A mixed methods approach was used involving a review of the literature, a questionnaire survey of UK public library authorities and five case studies of selected authorities. A majority of UK public library authorities offer Wi-Fi access to the public at one or more of their libraries and they generally have an authentication system in place for their users. The majority of survey respondents that provide Wi-Fi use filtering software. There are similarities and differences in the ways that public libraries and commercial outlets provide and manage access to their wireless networks. Differences mainly relate to security and privacy: these differences reflect to an extent the underlying purposes of providing public Wi-Fi access as well as legal obligations. In some ways, public library Wi-Fi access is better managed than commercially provided public services. Evidence from the case studies suggests reluctant acceptance of filtering on the part of public library authorities, based on a perceived need to balance providing access to information with providing a safe and trusted public space for all

¹⁴C AMS at SUERC: improving QA data from the 5 MV tandem AMS and 250 kV SSAMS

In 2003, a National Electrostatics Corporation (NEC) 5MV tandem accelerator mass spectrometer was installed at SUERC, providing the radiocarbon laboratory with 14C measurements to 4–5‰ repeatability. In 2007, a 250kV single-stage accelerator mass spectrometer (SSAMS) was added to provide additional 14C capability and is now the preferred system for 14C analysis. Changes to the technology and to our operations are evident in our copious quality assurance data: typically, we now use the 134-position MC-SNICS source, which is filled to capacity. Measurement of standards shows that spectrometer running without the complication of on-line δ13C evaluation is a good operational compromise. Currently, 3‰ 14C/13C measurements are routinely achieved for samples up to nearly 3 half-lives old by consistent sample preparation and an automated data acquisition algorithm with sample random access for measurement repeats. Background and known-age standard data are presented for the period 2003–2008 for the 5MV system and 2007–2008 for the SSAMS, to demonstrate the improvements in data quality

Significance of Population Centers As Sources of Gaseous and Dissolved PAHs in the Lower Great Lakes

Polyethylene passive samplers (PEs) were used to measure concentrations of gaseous and dissolved polycyclic aromatic hydrocarbons (PAHs) in the air and water throughout the lower Great Lakesduring summer and fall of 2011. Atmospheric Σ15PAH­ concentrations ranged from 2.1 ng/m3 in Cape Vincent (NY) to 76.4 ng/m3 in downtown Cleveland (OH). Aqueous Σ18PAH concentrations ranged from 2.4 ng/L at an offshoreLake Erie site to 30.4 ng/L in Sheffield Lake (OH). Gaseous PAH concentrations correlated strongly with population within 3-40 km of the sampling site depending on the compound considered, suggesting that urban centers are a primary source of gaseous PAHs (except retene) in the lowerGreat Lakes region. The significance of distant population (within 20 km) versus local population (within 3 km) increased with sub-cooled liquid vapor pressure. Most dissolved aqueous PAHs did not correlate significantly with population, nor were they consistently related to river discharge, wastewater effluents, or precipitation. Air-water exchange calculations implied that diffusive exchange was a source of phenanthrene to surface waters, while acenaphthylene volatilized out of the lakes. Comparison of air-water fluxes with temperature suggested that the significance of urban centers as sources of dissolved PAHs via diffusive exchange may decrease in warmer months

Consumer and carer consultants in mental health: The formation of their role identity

Following the introduction of the first National Mental Health Plan in 1992 consumer participation was and continues to be identified as a key component of the reform of Australia's mental health services. One strategy to achieve participation has been the creation of the role of consumer and carer consultants (CCCs) who have been employed in public mental health services since the early 1990s. Despite over two decades of service by CCCs there seems to be little consensus between the CCCs and mental health professionals regarding the roles and function of these positions. This qualitative study sought to explore the question of 'what is the role of consultants?' from the perspective of CCCs, focusing in particular on the formation of CCCs' role identity. Four themes were identified, namely: role motivation; role preparation; role practice/focus; and role ambiguity/conflict. This paper explores these themes and their implications, and finally makes recommendations regarding clinical practice

Concentrations of Polychlorinated Biphenyls (PCB’s), Chlorinated Pesticides, and Heavy Metals and Other Elements in Tissues of Belugas, Delphinapterus leucas, from Cook Inlet

Tissues from Cook Inlet beluga whales, Delphinapterus leucas, that were collected as part of the Alaska Marine Mammal Tissue Archival Project were analyzed for polychlorinated biphenyls (PCB’s), chlorinated pesticides, and heavy metals and other elements. Concentrations of total PCB’s (ΣPCB’s), total DDT (ΣDDT), chlordane compounds, hexachlorobenzene (HCB), dieldrin, mirex, toxaphene, and hexachlorocyclohexane (HCH) measured in Cook Inlet beluga blubber were compared with those reported for belugas from two Arctic Alaska locations (Point Hope and Point Lay), Greenland, Arctic Canada, and the highly contaminated stock from the St. Lawrence estuary in eastern Canada. The Arctic and Cook Inlet belugas had much lower concentrations (ΣPCB’s and ΣDDT were an order of magnitude lower) than those found in animals from the St. Lawrence estuary. The Cook Inlet belugas had the lowest concentrations of all (ΣPCB’s aver-aged 1.49 ± 0.70 and 0.79 ± 0.56 mg/kg wet mass, and ΣDDT averaged 1.35 ± 0.73 and 0.59 ± 0.45 mg/kg in males and females, respectively). Concentrations in the blubber of the Cook Inlet males were significantly lower than those found in the males of the Arctic Alaska belugas (ΣPCB’s and ΣDDT were about half). The lower levels in the Cook Inlet animals might be due to differences in contaminant sources, food web differences, or different age distributions among the animals sampled. Cook Inlet males had higher mean and median concentrations than did females, a result attributable to the transfer of these compounds from mother to calf during pregnancy and during lactation. Liver concentrations of cadmium and mercury were lower in the Cook Inlet belugas (most cadmium values were <1 mg/kg and mercury values were 0.704–11.42 mg/kg wet mass), but copper levels were significantly higher in the Cook Inlet animals (3.97–123.8 mg/kg wet mass) than in Arctic Alaska animals and similar to those reported for belugas from Hudson Bay. Although total mercury levels were the lowest in the Cook Inlet population, methylmercury concentrations were similar among all three groups of the Alaska animals examined (0.34–2.11 mg/kg wet mass). As has been reported for the Point Hope and Point Lay belugas, hepatic concentrations of silver were r

On representations of super coalgebras

The general structure of the representation theory of a $Z_2$-graded coalgebra is discussed. The result contains the structure of Fourier analysis on compact supergroups and quantisations thereof as a special case. The general linear supergroups serve as an explicit illustration and the simplest example is carried out in detail.Comment: 18 pages, LaTeX, KCL-TH-94-