768 research outputs found

    A window to quantum gravity phenomena in the emergence of the seeds of cosmic structure

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    Inflationary cosmology has, in the last few years,received a strong dose of support from observations. The fact that the fluctuation spectrum can be extracted from the inflationary scenario through an analysis that involves quantum field theory in curved space-time, and that it coincides with the observational data has lead to a certain complacency in the community, which prevents the critical analysis of the obscure spots in the derivation. We argue here briefly, as we have discussed in more detail elsewhere, that there is something important missing in our understanding of the origin of the seeds of Cosmic Structure, as is evidenced by the fact that in the standard accounts the inhomogeneity and anisotropy of our universe seems to emerge from an exactly homogeneous andisotropic initial state through processes that do not break those symmetries. This article gives a very brief recount of the problems faced by the arguments based on established physics. The conclusion is that we need some new physics to be able to fully address the problem. The article then exposes one avenue that has been used to address the central issue and elaborates on the degree to which, the new approach makes different predictions from the standard analyses. The approach is inspired on Penrose's proposals that Quantum Gravity might lead to a real, dynamical collapse of the wave function, a process that we argued has the properties needed to extract us from the theoretical impasse described above.Comment: 13 pages, 3 figures. To appear in DICE 2008 conference proceeding

    Middle Segment Pancreatectomy: A Useful Tool in the Management of Pancreatic Neoplasms

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    Small, benign, or low-grade malignant tumors located in the neck of the pancreas are usually treated with enucleation. However, if enucleation is too risky because of possible damage of the main pancreatic duct, standard pancreatic resections are performed. Such operations can lead to impaired long-term exocrine–endocrine function. Middle segment pancreatectomy consists of a limited resection of the midportion of the pancreas and can be performed in selected patients affected by tumors of the pancreatic neck. Middle segment pancreatectomy is a safe and feasible procedure for treating tumors of the pancreatic neck; in experienced hands it is associated with no mortality but with high morbidity, even if the rate of “clinical” pancreatic fistula is about 20%. Moreover, it allows a surgeon to preserve pancreatic parenchyma and consequently long-term endocrine and exocrine pancreatic function

    Genomic regions of durum wheat involved in water productivity

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    Durum wheat is a staple food of the Mediterranean Basin, mostly cultivated under rainfed conditions. As such, the crop is often exposed to moisture stress. Therefore, the identification of genetic factors controlling the capacity of genotypes to convert moisture into grain yield (i.e., water productivity) is quintessential to stabilize production despite climatic variations. A global panel of 384 accessions was tested across eighteen Mediterranean environments (Morocco, Lebanon, and Jordan) representing a vast range of moisture levels. The accessions were assigned to water responsiveness classes, with genotypes ‘Responsive to Low Moisture’ reaching an average + 1.5 kg ha -1 mm -1 yield advantage. Genome wide association studies (GWAS) revealed that six loci explained most of this variation. A second validation panel tested under moisture stress confirmed that carrying the positive allele at three loci on chromosomes 1B, 2A, and 7B generated an average water productivity gain of + 2.2 kg ha -1 mm -1. These three loci were tagged by Kompetitive Allele Specific PCR (KASP) markers, and these were used to screen a third independent validation panel composed of elites tested across moisture-stressed sites. The three KASP combined predicted up to 10% of the variation for grain yield at 60% accuracy. These loci are now ready for molecular pyramiding and transfer across cultivars to improve the moisture conversion of durum wheat

    Scattering and duality in the 2 dimensional OSP(2|2) Gross Neveu and sigma models

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    We write the thermodynamic Bethe ansatz for the massive OSp(2|2) Gross Neveu and sigma models. We find evidence that the GN S matrix proposed by Bassi and Leclair [12] is the correct one. We determine features of the sigma model S matrix, which seem highly unconventional; we conjecture in particular a relation between this sigma model and the complex sine-Gordon model at a particular value of the coupling. We uncover an intriguing duality between the OSp(2|2) GN (resp. sigma) model on the one hand, and the SO(4) sigma (resp. GN model) on the other, somewhat generalizing to the massive case recent results on OSp(4|2). Finally, we write the TBA for the (SUSY version of the) flow into the random bond Ising model proposed by Cabra et al. [39], and conclude that their S matrix cannot be correct.Comment: 41 pages, 27 figures. v2: minor revisio

    Long-term results of a phase II study of synchronous chemoradiotherapy in advanced muscle invasive bladder cancer.

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    We conducted a phase I/II study investigating synchronous chemoradiotherapy with mitomycin C and infusional 5-fluorouracil (5-FU) in muscle invasive bladder cancer. Early dose escalation results were previously published. We report the long-term toxicity and efficacy results with the optimised regimen. Patients with muscle invasive bladder cancer with glomerular filtration rate >25 ml min(-1) were eligible. Mitomycin (12 mg m(-2) on day 1 only) and infusional 5-FU (500 mg m(-2) day(-1)) for 5 days were administered during weeks 1 and 4 of radiotherapy of 55 Gy in 20 fractions. A total of 41 patients were enrolled, median age was 68 years, 33 were male and eight female patients. Out of the 41 patients, 20 (49%) had hydronephrosis at presentation and 25 (62%) had T3b or T4 disease. Four patients experienced Grade III thrombocytopenia and three patients had Grade III neutropenia. There were no episodes of febrile neutropenia. Four patients experienced Grade III diarrhoea and 1 Grade III urgency and dysuria. Six patients did not undergo cystoscopic evaluation due to early metastatic spread although there was no clinical suggestion of bladder failure. In all, out of 35 evaluable patients, 25 (71%) had macroscopic complete response at 3-month cystoscopy, and biopsy confirmed in 24 out of 25. A total of 16 (39%) patients remain alive with a median follow-up of 50.7 (range 23.5-68.8) months, 14 with a functioning bladder with no reported long-term treatment-related bladder or bowel toxicity. Five out of 41 patients have undergone salvage cystectomy: two for persistent CIS, two T1 and one muscle invasive recurrence. Four patients have received intravesical chemotherapy, of whom two remain alive with a functioning bladder. Overall 12-, 24- and 60-month (m) survival rates were 68, 49 and 36%. Local and distant progression free rates were 82 and 86% at 12-m and 79 and 75% at 24-m. Organ preservation using multimodality therapy is feasible and safe, even in patients with poor renal reserve, and does not compromise salvage therapies. A national phase III trial BC2001 (www.bc2001.org.uk) exploring the effects of synchronous chemoradiotherapy with this regimen is currently recruiting

    Total elbow arthroplasty: a prospective clinical outcome study of Discovery Elbow System with a 4-year mean follow-up

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    BACKGROUND: Total elbow arthroplasty (TEA) is increasingly used for the treatment of advanced elbow conditions to reduce pain and improve function. However, TEA is still associated with a higher complication rate than total hip and knee arthroplasty despite advances in the design and surgical techniques. This prospective clinical study reports the outcome of the Discovery Elbow System (Biomet, Warsaw IN, USA), which has been in clinical use in the United Kingdom since 2003. METHODS: The study included a total of 100 Discovery Elbows (April 2003 to January 2010) with a minimum 2-year follow-up, including 75 primary and 25 revisions (60% women and 40% men; mean age, 62 years). Outcome was assessed by means of the Liverpool Elbow Score, pain experience, patient satisfaction, range of motion, and radiographic imaging. RESULTS: The mean follow-up period was 48.5 months (range, 24-108 months). The Liverpool Elbow Score improved from 3.79 to 6.36 (P < .001). The percentage of pain-free patients was substantially increased from 7% preoperatively to 64% at the final follow-up. The patient satisfaction rate was over 90%. The flexion-extension arc and pronation-supination arc increased from 72° to 93° and from 86° to 111°, respectively (P < .001). Major postoperative complications included deep infection (2%), progressive aseptic loosening requiring revision (primary, 5%; revision 12%), persistent ulnar neuropathy (3%), and periprosthetic fracture (primary, 6.8%; revision, 8%). CONCLUSION: The Discovery Elbow System resulted in improved function, reduced pain, and high patient satisfaction. Long-term results are required to assess the survivorship of this syste
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