1,124 research outputs found
A case control study to determine the association between Perthesâ disease and the recalled use of tobacco during pregnancy, and biological markers of current tobacco smoke exposure
Aims: It is well established that there is a strong association between Perthesâ disease and worsening socioeconomic deprivation. It has been suggested that the primary determinant driving this association is exposure to tobacco smoke. This study aimed to examine this hypothesis. Patients and Methods: A hospital case-control study (n = 149/146) examined the association between tobacco smoke exposure and Perthesâ disease, adjusting for area-level socioeconomic deprivation. Tobacco smoke exposure was assessed by parental questionnaire of smoking habits during pregnancy, and by quantitative assay of current exposure using the urinary cotinine-creatinine ratio, which is a widely used and validated measure of tobacco smoke exposure. Results: The odds of Perthesâ disease significantly increased with reported in utero exposure after adjustment for socioeconomic deprivation (maternal smoking odds ratio (OR) 2.06, 95% confidence interval (CI) 1.17 to 3.63; paternal smoking OR 2.09, 95% CI 1.26 to 3.46). The cotinine-creatinine ratio was significantly greater in cases, OR 1.63 (95% CI 1.09 to 2.43), suggesting a greater âdoseâ of current tobacco exposure. Conclusion: An association exists between tobacco smoke exposure and Perthesâ disease but we remain unable to disentangle the association with socioeconomic deprivation
Thermocline management of stratified tanks for heat storage
Stratified tanks are useful for maximising the thermal energy efficiency of non-continuous and semi-continuous processes. Liquid at two or more dissimilar temperatures is stored within the same tank to provide a buffer for variations in heating and cooling loads. Control of the thermocline between the hot and cold fluid regions is needed to minimise thermocline growth and maximise operation of the storage tank. An experimental programme using a scale model of an industrial stratified tank (aspect ratio 3.5) and Perspex tank (aspect ratio 8.2) is reported. The behaviour and growth of the hot-cold thermocline under various operating conditions is presented. A siphoning method to re-establish the thermocline without interrupting the use of the tank is tested. Siphoning of the thermocline region from either 20%, 50% or 80% of the tank height is an effective strategy for uninterrupted interface re-establishment. However, the rate and position of siphoning and the load balance of the exit streams are critical variables for minimising the time for effective re-establishment of the two temperature zones
Bound States of D-Branes and the Non-Abelian Born-Infeld Action
We attempt to settle the issue as to what is the correct non-abelian
generalisation of the Born-Infeld action, via a consideration of the two-loop
--function for the non-abelian background gauge field in open string
theory. An analysis of the bosonic theory alone shows the recent proposal of
Tseytlin's to be somewhat lacking. For the superstring, however, this proposal
would seem to be correct, and not just within the approximation used in
\cite{tseytlin}. Since it is this latter case that is relevant to the
description of D-branes we, in effect, obtain an independent verification of
Tseytlin's result. Some issues involved in the concept of non-abelian
T--duality are discussed; and it is shown how the interaction between separated
and parallel branes, in the form of massive string states, emerges.Comment: 24 pages, 4 eps figures, LaTeX. Further comments concerning earlier
work added, minor typos corrected. Version to be published in Nucl. Phys.
Mid-Holocene sea surface conditions and riverine influence on the inshore Great Barrier Reef.
We present measurements of Sr/Ca, d18O, and spectral luminescence ratios (G/B) from a mid-Holocene Porites sp. microatoll recovered from the nearshore Great Barrier Reef (GBR). These records were used as proxies to reconstruct sea surface temperature (SST), the d18O of surrounding seawater (d18Osw), and riverine influence, respectively, and compared with records from a modern Porites sp. microatoll growing in the same environment. Strong riverine influence in the mid-Holocene record is indicated by (1) an increased annual d18Osw range in the mid-Holocene record, (2) negative peaks in d18O characteristic of flood events, and (3) a higher G/B luminescence ratio. Seasonal cycles in G/B suggest that humic acid inputs were elevated for a longer portion of the year during the mid-Holocene. The seasonal cycle of d18Osw peaked earlier in the year in the mid-Holocene record relative to the modern, while mean d18Osw values from the mid-Holocene record were similar to modern values. These records provide an insight into the oceanographic conditions the nearshore GBR experienced during mid-Holocene climatic shifts and are consistent with a strong AustralianâIndonesian Summer Monsoon (AISM) system at ~ 4700 cal. yr BP
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Prophylaxis pharmacotherapy to prevent the onset of post traumatic brain injury depression: a systematic review
YesBackground: Depression is a common psychiatric problem following traumatic brain injury (TBI) with reported prevalence rates of 30-77% in the first year post-TBI. Given the negative influence of post-TBI depression on cognition, interpersonal, social, physical and occupational functioning; early initiation of pharmacotherapy to prevent post-TBI depression has been considered. This systematic review will synthesize the available evidence from published studies on the effectiveness and harms of pharmacotherapy for the secondary prevention of post-TBI depression.
Method: Studies published before November 2017 were reviewed. Six databases were searched, with additional searching of key additional documents. Studies meeting inclusion criteria were evaluated for methodological quality.
Results: Six articles addressing five studies met inclusion criteria. Study designs included three randomised controlled trials (RCT), two retrospective cohorts and one case-control. Prophylactic pharmacotherapy included antidepressants, beta-blockers and statins. In one RCT, the number-needed-to-treat with sertraline to prevent one case of depression post-TBI at 24 weeks was 5.9 (95%CI: 3.1-71.1). Prescribing beta-blockers prior to TBI reduced the depression risk regardless of the specific brain trauma. TBI patients with pre-existing hyperlipidemia not treated with statins had an increased depression risk compared to those without hyperlipidemia.
Conclusion: Early initiation of sertraline prophylaxis in nondepressed TBI patients shows promise to reduce the odds of post-TBI depression developing. However, in the absence of rigorous study of tolerability, existing data are insufficient to recommend sertraline prophylaxis. Optimal timing and treatment duration with identification of patients most likely to benefit from prophylaxis require further consideration. Dedicated prospective studies assessing the effects of beta-blockers and statins on post-TBI depression are required.The Transport Accident Commission (TAC), through the Institute for Safety, Compensation and Recovery Research (ISCRR) at Monash University, provided funding for this review
Molecular diversity within clonal complex 22 methicillin-resistant Staphylococcus aureus encoding PantonâValentine leukocidin in England and Wales
AbstractPantonâValentine leukocidin (PVL)-positive methicillin-resistant Staphylococcus aureus (MRSA) that are multi-locus sequence type clonal complex 22 (CC22) comprise a significant public health problem in the UK. In the present study we sought to determine the genetic diversity, and the respective patient demographics, among 47 PVL-MRSA with a CC22 pulsotype that occurred sporadically or in clusters in community and healthcare settings in eight of nine geographic regions in England and Wales between January 2005 and September 2007. Patient demographics and disease presentations were typical for PVL-S. aureus infections (mostly skin and soft tissue infections in individuals <40 years old); one patient with community-acquired pneumonia died. Although the isolates were closely genotypically related by spa typing and pulsed field gel electrophoresis, at least two variant groups were suggested. PCR detections demonstrated that the majority of the CC22 PVL-MRSA identified (n = 42; 89%) harboured SCCmecIVc, three had SCCmecIVd, one had SCCmecIV but was non-subtypeable, and one isolate harboured SCCmecV. At least three different PVL-encoding phages were detected: ΊPVL, Ί108PVL and an unidentified icosahedral phage. Agar dilution MIC determinations showed that the CC22 PVL-MRSA identified were typically resistant to gentamicin and trimethoprim (43 of 47 isolates) and ciprofloxacin resistance was also noted in six isolates. In conclusion, the CC22 PVL-MRSA tested were geographically disseminated but highly genetically related. The observed variances in acquired elements (most notably SCCmec and PVL-encoding phages) suggested that CC22 PVL-MRSA in England and Wales have evolved on multiple occasions
Gauge Dyonic Strings and Their Global Limit
We show that six-dimensional supergravity coupled to tensor and Yang-Mills
multiplets admits not one but two different theories as global limits, one of
which was previously thought not to arise as a global limit and the other of
which is new. The new theory has the virtue that it admits a global
anti-self-dual string solution obtained as the limit of the curved-space gauge
dyonic string, and can, in particular, describe tensionless strings. We
speculate that this global model can also represent the worldvolume theory of
coincident branes. We also discuss the Bogomol'nyi bounds of the gauge dyonic
string and show that, contrary to expectations, zero eigenvalues of the
Bogomol'nyi matrix do not lead to enhanced supersymmetry and that negative
tension does not necessarily imply a naked singularity.Comment: Latex, 22 pages, References added and discussion altere
Ricci-Flat Branes
Up to overall harmonic factors, the D8-brane solution of the massive type IIA
supergravity theory is the product of nine-dimensional Minkowski space (the
worldvolume) with the real line (the transverse space). We show that the
equations of motion allow for the worldvolume metric to be generalised to an
arbitrary Ricci-flat one. If this nine-dimensional Ricci-flat manifold admits
Killing spinors, then the resulting solutions are supersymmetric and satisfy
the usual Bogomol'nyi bound, although they preserve fewer than the usual one
half of the supersymmetries. We describe the possible choices of such
manifolds, elaborating on the connection between the existence of Killing
spinors and the self-duality condition on the curvature two-form. Since the
D8-brane is a domain wall in ten dimensions, we are led to consider the general
case: domain walls in any supergravity theory. Similar considerations hold here
also. Moreover, it is shown that the worldvolume of any magnetic brane --- of
which the domain walls are a specific example --- can be generalised in
precisely the same way. The general class of supersymmetric solutions have
gravitational instantons as their spatial sections. Some mention is made of the
worldvolume solitons of such branes.Comment: 26 pages, LaTe
Aspects of Superembeddings
Some aspects of the geometry of superembeddings and its application to
supersymmetric extended objects are discussed. In particular, the embeddings of
(3|16) and (6|16) dimensional superspaces into (11|32) dimensional superspace,
corresponding to supermembranes and superfivebranes in eleven dimensions, are
treated in some detail.Comment: 13 pages, Latex, Contribution to Supersymmetry and Quantum Field
Theory, International Seminar dedicated to the memory of D. V. Volkov
(Kharkov, 1997), some clarifications are mad
Magnetic ordering of Mn sublattice, dense Kondo lattice behavior of Ce in (RPd3)8Mn (R = La, Ce)
We have synthesized two new interstitial compounds (RPd3)8Mn (R = La and Ce).
The Mn ions present in "dilute" concentration of just 3 molar percent form a
sublattice with an unusually large Mn-Mn near neighbor distance of ~ 85 nm.
While the existence of (RPd3)8M (where M is a p-block element) is already
documented in the literature, the present work reports for the first time the
formation of this phase with M being a 3d element. In (LaPd3)8Mn, the Mn
sub-lattice orders antiferromagnetically as inferred from the peaks in
low-field magnetization at 48 K and 23 K. The latter peak progressively shifts
towards lower temperatures in increasing magnetic field and disappears below
1.8 K in a field of ~ 8 kOe. On the other hand in (CePd3)8Mn the Mn sublattice
undergoes a ferromagnetic transition around 35 K. The Ce ions form a dense
Kondo-lattice and are in a paramagnetic state at least down to 1.5 K. A
strongly correlated electronic ground state arising from Kondo effect is
inferred from the large extrapolated value of C/T = 275 mJ/Ce-mol K^2 at T = 0
K. In contrast, the interstitial alloys RPd3Mnx (x = 0.03 and 0.06), also
synthesized for the first time, have a spin glass ground state due to the
random distribution of the Mn ions over the available "1b" sites in the parent
RPd3 crystal lattice.Comment: 18 figures and 20 pages of text documen
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