290 research outputs found

    Boltzmann equation in de Sitter space

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    In a time dependent background like de Sitter space, Feynman-Dyson perturbation theory breaks down due to infra-red divergences. We investigate an interacting scalar field theory in Schwinger-Keldysh formalism. We derive a Boltzmann equation from a Schwinger-Dyson equation inside the cosmological horizon. Our solution shows that the particle production is compensated by the reduction of the on-shell states due to unitarity. Although the degrees of freedom inside the horizon leads to a small and diminishing screening effect of the cosmological constant, there is a growing screening effect from those outside the horizon.Comment: 33pages, 2figure

    Breath Hydrogen Gas Concentration Linked to Intestinal Gas Distribution and Malabsorption in Patients with Small-bowel Pseudo-obstruction

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    Background: The patient with colonic obstruction may frequently have bacterial overgrowth and increased breath hydrogen (H2) levels because the bacterium can contact with food residues for longer time. We experienced two cases with intestinal obstruction whose breath H2 concentrations were measured continuously.Case 1: A 70-year-old woman with small bowel obstruction was treated with a gastric tube. When small bowel gas decreased and colonic gas was demonstrated on the plain abdominal radiograph, the breath H2 concentration increased to 6 ppm and reduced again shortly.Case 2: A 41-year-old man with functional small bowel obstruction after surgical treatment was treated with intravenous administration of erythromycin. Although the plain abdominal radiograph demonstrated a decrease of small-bowel gas, the breath H2 gas kept the low level. After a clear-liquid meal was supplied, fasting breath H2 concentration increased rapidly to 22 ppm and gradually decreased to 9 ppm despite the fact that the intestinal gas was unchanged on X-ray. A rapid increase of breath H2 concentration may reflect the movement of small bowel contents to the colon in patients with small-bowel pseudo-obstruction or malabsorption following diet progression.Conclusions: Change in breath H2 concentration had a close association with distribution and movement of intestinal gas

    Free-space optical channel estimation for physical layer security

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    We present experimental data on message transmission in a free-space optical (FSO) link at an eye-safe wavelength, using a testbed consisting of one sender and two receiver terminals, where the latter two are a legitimate receiver and an eavesdropper. The testbed allows us to emulate a typical scenario of physical-layer (PHY) security such as satellite-to-ground laser communications. We estimate information-theoretic metrics including secrecy rate, secrecy outage probability, and expected code lengths for given secrecy criteria based on observed channel statistics. We then discuss operation principles of secure message transmission under realistic fading conditions, and provide a guideline on a multi-layer security architecture by combining PHY security and upper-layer (algorithmic) security

    Place of death trends among patients with dementia in Japan: a population-based observational study

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    Dementia is a major public health concern in ageing societies. Although the population of Japan is among the most aged worldwide, long-term trends in the place of death (PoD) among patients with dementia is unknown. In this Japanese nationwide observational study, we analysed trends in PoD using the data of patients with dementia who were aged >= 65 years and died during 1999-2016. Trends in the crude death rates and PoD frequencies were analysed using the Joinpoint regression model. Changes in these trends were assessed using the Joinpoint regression analysis in which significant change points, the annual percentage change (APC) and average APCs (AAPC) in hospitals, homes, or nursing homes were estimated. During 1999-2016, the number of deaths among patients with dementia increased from 3,235 to 23,757 (total: 182,000). A trend analysis revealed increased mortality rates, with an AAPC of 8.2% among men and 9.3% among women. Most patients with dementia died in the hospital, although the prevalence of hospital deaths decreased (AAPC: -1.0%). Moreover, the prevalence of nursing home deaths increased (AAPC: 5.6%), whereas the prevalence of home deaths decreased (AAPC: -5.8%). These findings support a reconsideration of the end-of-life care provided to patients with dementia

    Testicular Torsion in Undescended Testis : A Case Report and View of Sixty-two Cases in Japan

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    A 7-year-old boy with cerebral palsy was presented with a progressively enlarging tender, left inguinal mass. Examination revealed absence of the left testis in the scrotal sac. The left testis was palpable in the left superficial inguinal pouch. The right testis was normaly palpable in the right scrotum. A diagnosis of a torsion in the undescended left testis was confirmed by exploratory surgery. Orchidectomy of the left testis was performed and the remainder of the patient\u27s course was uneventful. We presented this case to describe the clinical features of testicular torsion in the undescended testis with a review of 62 cases in Japan. Specific emphasis was placed on the incidence, relationship of cerebral palsy to torsion, diagnosis, and treatment of testicular torsion in cryptorchidism

    Extensive Atrophic Gastritis Increases Intraduodenal Hydrogen Gas

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    Objective. Gastric acid plays an important part in the prevention of bacterial colonization of the gastrointestinal tract. If these bacteria have an ability of hydrogen (H2) fermentation, intraluminal H2 gas might be detected. We attempted to measure the intraluminal H2 concentrations to determine the bacterial overgrowth in the gastrointestinal tract. Patients and methods. Studies were performed in 647 consecutive patients undergoing upper endoscopy. At the time of endoscopic examination, we intubated the stomach and the descending part of the duodenum without inflation by air, and 20 mL of intraluminal gas samples of both sites was collected through the biopsy channel. Intraluminal H2 concentrations were measured by gas chromatography. Results. Intragastric and intraduodenal H2 gas was detected in 566 (87.5%) and 524 (81.0%) patients, respectively. The mean values of intragastric and intraduodenal H2 gas were 8.5 ± 15.9 and 13.2 ± 58.0 ppm, respectively. The intraduodenal H2 level was increased with the progression of atrophic gastritis, whereas the intragastric H2 level was the highest in patients without atrophic gastritis. Conclusions. The intraduodenal hydrogen levels were increased with the progression of atrophic gastritis. It is likely that the influence of hypochlorhydria on bacterial overgrowth in the proximal small intestine is more pronounced, compared to that in the stomach

    Revisiting museum collections in the genomic era: potential of MIG-seq for retrieving phylogenetic information from aged minute dry specimens of ants (Hymenoptera: Formicidae) and other small organisms

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    Multiplexed inter-simple sequence repeat genotyping by sequencing – MIG-seq – is an effective PCR-based method for genome-wide SNP detection using the Next-Generation Sequencing platform, and it provides a potential solution to a central problem in museomics – the difficulties of obtaining useful sequence data from aged specimens with often degraded and / or low yields of DNA. We demonstrate and validate the cost effectiveness and utility of the MIG-seq workflow in obtaining useful and robust sequence data from aged museum specimens. We applied the MIG-seq approach to 55 aged (10 - 23 years old) millimeter-sized dry-mounted specimens of the hyper-diverse ant genus Pheidole. A total of 50,782,736 reads were generated from the 55 samples (259,902 - 3,693,375 reads per sample). The reads corresponded to 36,862 SNPs from 4,849 polymorphic loci; the SNP dataset was then used to construct a Bayesian phylogenetic tree. The topology of the phylogenetic tree was highly compatible with existing knowledge of phylogenetic relationships among species of Pheidole. Therefore, we recommend the MIG-seq method as a cost-effective and highly applicable pipeline for conducting phylogenetic and population genetic studies on aged museum specimens, potentially enhancing the relevance of specimen repositories in general towards modern biodiversity science and conservation biology
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