150 research outputs found

    Galilean quantum gravity with cosmological constant and the extended q-Heisenberg algebra

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    We define a theory of Galilean gravity in 2+1 dimensions with cosmological constant as a Chern-Simons gauge theory of the doubly-extended Newton-Hooke group, extending our previous study of classical and quantum gravity in 2+1 dimensions in the Galilean limit. We exhibit an r-matrix which is compatible with our Chern-Simons action (in a sense to be defined) and show that the associated bi-algebra structure of the Newton-Hooke Lie algebra is that of the classical double of the extended Heisenberg algebra. We deduce that, in the quantisation of the theory according to the combinatorial quantisation programme, much of the quantum theory is determined by the quantum double of the extended q-deformed Heisenberg algebra.Comment: 22 page

    On the Decomposition of Clifford Algebras of Arbitrary Bilinear Form

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    Clifford algebras are naturally associated with quadratic forms. These algebras are Z_2-graded by construction. However, only a Z_n-gradation induced by a choice of a basis, or even better, by a Chevalley vector space isomorphism Cl(V) \bigwedge V and an ordering, guarantees a multi-vector decomposition into scalars, vectors, tensors, and so on, mandatory in physics. We show that the Chevalley isomorphism theorem cannot be generalized to algebras if the Z_n-grading or other structures are added, e.g., a linear form. We work with pairs consisting of a Clifford algebra and a linear form or a Z_n-grading which we now call 'Clifford algebras of multi-vectors' or 'quantum Clifford algebras'. It turns out, that in this sense, all multi-vector Clifford algebras of the same quadratic but different bilinear forms are non-isomorphic. The usefulness of such algebras in quantum field theory and superconductivity was shown elsewhere. Allowing for arbitrary bilinear forms however spoils their diagonalizability which has a considerable effect on the tensor decomposition of the Clifford algebras governed by the periodicity theorems, including the Atiyah-Bott-Shapiro mod 8 periodicity. We consider real algebras Cl_{p,q} which can be decomposed in the symmetric case into a tensor product Cl_{p-1,q-1} \otimes Cl_{1,1}. The general case used in quantum field theory lacks this feature. Theories with non-symmetric bilinear forms are however needed in the analysis of multi-particle states in interacting theories. A connection to q-deformed structures through nontrivial vacuum states in quantum theories is outlined.Comment: 25 pages, 1 figure, LaTeX, {Paper presented at the 5th International Conference on Clifford Algebras and their Applications in Mathematical Physics, Ixtapa, Mexico, June 27 - July 4, 199

    Frequency and severity of myocardial perfusion abnormalities using Tc-99m MIBI SPECT in cardiac syndrome X

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    BACKGROUND: Cardiac syndrome X is defined by a typical angina pectoris with normal or near normal (stenosis <40%) coronary angiogram with or without electrocardiogram (ECG) change or atypical angina pectoris with normal or near normal coronary angiogram plus a positive none-invasive test (exercise tolerance test or myocardial perfusion scan) with or without ECG change. Studies with myocardial perfusion imaging on this syndrome have indicated some abnormal perfusion scan. We evaluated the role of myocardial perfusion imaging (MPI) and also the severity and extent of perfusion abnormality using Tc-99m MIBI Single Photon Emission Computed Tomography (SPECT) in these patients. METHODS: The study group consisted of 36 patients with cardiac syndrome X. The semiquantitative perfusion analysis was performed using exercise Tc-99m MIBI SPECT. The MPI results were analyzed by the number, location and severity of perfusion defects. RESULTS: Abnormal perfusion defects were detected in 13 (36.10%) cases, while the remaining 23 (63.90%) had normal cardiac imaging. Five of 13 (38.4%) abnormal studies showed multiple perfusion defects. The defects were localized in the apex in 3, apical segments in 4, midventricular segments in 12 and basal segments in 6 cases. Fourteen (56%) of all abnormal segments revealed mild, 7(28%) moderate and 4 (16%) severe reduction of tracer uptake. No fixed defects were identified. The vessel territories were approximately the same in all subjects. The Exercise treadmill test (ETT) was positive in 25(69%) and negative in 11(30%) patients. There was no consistent pattern as related to the extent of MPI defects or exercise test results. CONCLUSION: Our study suggests that multiple perfusion abnormalities with different levels of severity are common in cardiac syndrome X, with more than 30 % of these patients having at least one abnormal perfusion segment. Our findings suggest that in these patients microvascular angina is probably more common than is generally believed

    Swearing, Euphemisms, and Linguistic Relativity

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    Participants read aloud swear words, euphemisms of the swear words, and neutral stimuli while their autonomic activity was measured by electrodermal activity. The key finding was that autonomic responses to swear words were larger than to euphemisms and neutral stimuli. It is argued that the heightened response to swear words reflects a form of verbal conditioning in which the phonological form of the word is directly associated with an affective response. Euphemisms are effective because they replace the trigger (the offending word form) by another word form that expresses a similar idea. That is, word forms exert some control on affect and cognition in turn. We relate these findings to the linguistic relativity hypothesis, and suggest a simple mechanistic account of how language may influence thinking in this context

    A randomised feasibility study of EPA and Cox-2 inhibitor (Celebrex) versus EPA, Cox-2 inhibitor (Celebrex), Resistance Training followed by ingestion of essential amino acids high in leucine in NSCLC cachectic patients - ACCeRT Study

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    <p>Abstract</p> <p>Background</p> <p>Cancer cachexia is a syndrome of progressive weight loss. Non-small cell lung cancer patients experience a high incidence of cachexia of 61%. Research into methods to combat cancer cachexia in various tumour sites has recently progressed to the combination of agents.</p> <p>The combination of the anti-cachectic agent Eicosapentaenoic acid (EPA) and the cyclo-oxygenase-2 (COX-2) inhibitor celecoxib has been tested in a small study with some benefit. The use of progressive resistance training (PRT) followed by the oral ingestion of essential amino acids (EAA), have shown to be anabolic on skeletal muscle and acceptable in older adults and other cancer groups.</p> <p>The aim of this feasibility study is to evaluate whether a multi-targeted approach encompassing a resistance training and nutritional supplementation element is acceptable for lung cancer patients experiencing cancer cachexia.</p> <p>Methods/Design</p> <p>Auckland's Cancer Cachexia evaluating Resistance Training (ACCeRT) is an open label, prospective, randomised controlled feasibility study with two parallel arms. All patients will be treated with EPA and the COX-2 inhibitor celecoxib on an outpatient basis at the study site. In the experimental group patients will participate in PRT twice a week, followed by the ingestion of essential amino acids high in leucine. A total of 21 patients are planned to be enrolled. Patients will be randomised using 1:2 ratio with 7 patients enrolled into the control arm, and 14 patients into the treatment arm. The primary endpoint is the acceptability of the above multi-targeted approach, determined by an acceptability questionnaire.</p> <p>Discussion</p> <p>To our knowledge ACCeRT offers for the first time the opportunity to investigate the effect of stimulating the anabolic skeletal muscle pathway with the use of PRT along with EAA alongside the combination of EPA and celecoxib in this population.</p> <p>Trial registration</p> <p>Netherlands Trial Register (NTR): <a href="http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=2040">ACTRN12611000870954</a></p

    RNA Silencing of Mcl-1 Enhances ABT-737-Mediated Apoptosis in Melanoma: Role for a Caspase-8-Dependent Pathway

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    BACKGROUND: Malignant melanoma is resistant to almost all conventional forms of chemotherapy. Recent evidence suggests that anti-apoptotic proteins of the Bcl-2 family are overexpressed in melanoma and may contribute to melanoma's striking resistance to apoptosis. ABT-737, a small-molecule inhibitor of Bcl-2, Bcl-xl and Bcl-w, has demonstrated efficacy in several forms of leukemia, lymphoma as well as solid tumors. However, overexpression of Mcl-1, a frequent observance in melanoma, is known to confer ABT-737 resistance. METHODOLOGY/PRINCIPAL FINDINGS: Here we report that knockdown of Mcl-1 greatly reduces cell viability in combination with ABT-737 in six different melanoma cell lines. We demonstrate that the cytotoxic effect of this combination treatment is due to apoptotic cell death involving not only caspase-9 activation but also activation of caspase-8, caspase-10 and Bid, which are normally associated with the extrinsic pathway of apoptosis. Caspase-8 (and caspase-10) activation is abrogated by inhibition of caspase-9 but not by inhibitors of the death receptor pathways. Furthermore, while caspase-8/-10 activity is required for the full induction of cell death with treatment, the death receptor pathways are not. Finally, we demonstrate that basal levels of caspase-8 and Bid correlate with treatment sensitivity. CONCLUSIONS/SIGNIFICANCE: Our findings suggest that the combination of ABT-737 and Mcl-1 knockdown represents a promising, new treatment strategy for malignant melanoma. We also report a death receptor-independent role for extrinsic pathway proteins in treatment response and suggest that caspase-8 and Bid may represent potential markers of treatment sensitivity

    Characterization of biodegradable polymer blends of acetylated and hydroxypropylated sago starch and natural rubber.

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    Development of biodegradable polymers from absolute environmental friendly materials has attracted increasing research interest due to public awareness of waste disposal problems caused by low degradable conventional plastics. In this study, the potential of incorporating natural rubber latex (NRL) into chemically modified sago starch for the making biodegradable polymer blends was assessed. Native sago starch was acetylated and hydroxypropylated before gelatinization in preparing starch thermoplastic using glycerol. They were than casted with NRL into biopolymer films according to the ratios of 100.00/0.00, 99.75/1.25, 98.50/2.50, 95.00/5.00, 90.00/10.00 and 80.00/20.00 wt/wt, via solution spreading technique. Water absorption, thermal, mechanical, morphological and biodegradable properties of the product films were evaluated by differential scanning calorimetry (DSC), universal testing machine (UTM), scanning electron microscopy (SEM) and fourier transform infrared spectroscopy. Results showed that acetylation promoted the incorporating behavior of NRL in sago starch by demonstrating a good adhesion characteristic and giving a uniform, homogenous micro-structured surface under SEM observation. However, the thin biopolymer films did not exhibit any remarkable trend in their DSC thermal profile and UTM mechanical properties. The occurrence of NRL suppressed water adsorption capacity and delayed the biodegradability of the biopolymer films in the natural environment. Despite the depletion in water adsorption capacity, all of the product films degraded 50 % within 12 weeks. This study concluded that biopolymers with desirable properties could be formulated by choosing an appropriate casting ratio of the sago starch to NRL with suitable chemical substitution modes
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