1,725 research outputs found

    Finite temperature superfluid density in very underdoped cuprates

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    The combination of a large superconducting gap, low transition temperature, and quasi two-dimensionality in strongly underdoped high temperature superconductors severely constrains the behavior of the ab-plane superfluid density \rho with temperature T. In particular, we argue that the contribution of nodal quasiparticles to \rho(T) is essential to account both for the amplitude of, and the recently observed deviations from, the Uemura scaling. A relation between T_c and \rho(0) which combines the effects of quasiparticle excitations at low temperatures and of vortex fluctuations near the critical temperature is proposed and discussed in light of recent experiments.Comment: 5 RevTex pages, 4 figures (one new); more discussion and comparison with experiment; version to appear in Phys. Rev.

    Visual-inertial self-calibration on informative motion segments

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    Environmental conditions and external effects, such as shocks, have a significant impact on the calibration parameters of visual-inertial sensor systems. Thus long-term operation of these systems cannot fully rely on factory calibration. Since the observability of certain parameters is highly dependent on the motion of the device, using short data segments at device initialization may yield poor results. When such systems are additionally subject to energy constraints, it is also infeasible to use full-batch approaches on a big dataset and careful selection of the data is of high importance. In this paper, we present a novel approach for resource efficient self-calibration of visual-inertial sensor systems. This is achieved by casting the calibration as a segment-based optimization problem that can be run on a small subset of informative segments. Consequently, the computational burden is limited as only a predefined number of segments is used. We also propose an efficient information-theoretic selection to identify such informative motion segments. In evaluations on a challenging dataset, we show our approach to significantly outperform state-of-the-art in terms of computational burden while maintaining a comparable accuracy

    The prion protein and New World primate phylogeny

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    The PrPC prion protein contains 250 amino acids with some variation among species and is expressed in several cell types. PrPC is converted to PrPSc by a post-translational process in which it acquires amino acid sequences of three-dimensional conformation of -sheets. Variations in the prion protein gene were observed among 16 genera of New World primates (Platyrrhini), and resulted in amino acid substitutions when compared with the human sequence. Seven substitutions not yet described in the literature were found: W R at position 31 in Cebuella, T A at position 95 in Cacajao and Chiropotes, N S at position 100 in Brachyteles, L Q at position 130 in Leontopithecus (in the sequence responsible for generating the -sheet 1), D E at position 144 in Lagothrix (in the sequence responsible for the -helix 1), D G at position 147 in Saguinus (also located in the -helix 1 region), and M I at position 232 in Alouatta. The phylogenetic trees generated by parsimony, neighbor-joining and Bayesian analyses strongly support the monophyletic status of the platyrrhines, but did not resolve relationships among families. However, the results do corroborate previous findings, which indicate that the three platyrrhine families radiated rapidly from an ancient split

    Sudden death after open gastric bypass surgery

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    Purpose: Gastric bypass surgery has become a relatively low-risk bariatric surgical intervention in a high-risk patient population (Nguyen et al., Arch Surg, 141:445-449, 2006; Buchwald et al. JAMA, 13:1724-1737, 2004). Surgical interventions in patients suffering from morbid obesity are typically associated with excess morbidity (Parikh et al., Am Surg, 73:959-962, 2007). Though overall mortality after bariatric surgery is <1% is low (Mason et al., Obes Surg, 17:9-14, 2007), some surgical complications such as anastomotic leaks, staple line disruption and bowel obstruction may still impact on postoperative outcome (Parikh et al., Am Surg, 73:959-962, 2007; Mason et al., Obes Surg, 17:9-14, 2007). Early symptoms are often missed, as clinical presentation may be discreet, inexistent or falsely attributed to obesity. Methods: This case report refers to a patient in whom discomfort and agitation associated with a rise in temperature heralded a fulminant septic shock syndrome precipitating his death. Literature on early complications and management after gastric bypass is reviewed. Conclusion: A high level of suspicion should be present in the case of an unexpected postoperative deterioration of the patient's general condition. Time to treat may be very short (Mason et al., Obes Surg, 17:9-14, 2007). Computed tomography is mandatory to rule out pulmonary embolism and bypass obstructio

    The Implementation of Scenarios using DSGE Models

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    The new generation of dynamic stochastic general equilibrium (DSGE) models seems particularly suited for conducting scenario analysis. These models formalise the behaviour of economic agents on the basis of explicit micro-foundations. As a result, they appear less prone to the Lucas critique than traditional macroeconometric models. DSGE models provide researchers with powerful tools, which allow for the design of a broad range of scenarios and can tackle a large range of issues, while at the same time offering an appealing structural interpretation of the scenario specification and simulation results. This paper provides illustrations of some of the modelling issues that often arise when implementing scenarios using DSGE models in the context of projection exercises or policy analysis. These issues reflect the sensitivity of DSGE model-based analysis to scenario assumptions, which in more traditional models are apparently less critical, such as, for example, scenario event anticipation and duration, as well as treatment of monetary and fiscal policy rules.Business fluctuations, monetary policy, fiscal policy, forecasting and simulation

    Tropical circulation and hydrological cycle response to orbital forcing

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    The intensity of the two major atmospheric tropical circulations, the Hadley and Walker circulation, has been analyzed in simulations with the Kiel Climate Model (KCM) of the early Eemian and the early Holocene, both warmer climate epochs compared to the late Holocene, or pre-industrial era. The KCM was forced by changes in orbital parameters corresponding to the early and late Holocene (9.5kyr BP and pre-industrial) and the early Eemian (126kyr BP). An intensification of the Southern Hemisphere (SH) winter Hadley cell and a northward extension of its rising branch, the Intertropical Convergence Zone, relative to pre-industrial are simulated for both warm periods. The Walker circulation's rising branch is shifted westward towards the Indian Ocean due to an increased zonal tropical sea surface temperature (SST) gradient across the Indo-Pacific Ocean, which drives enhanced easterlies over this region. The simulated vertically-integrated water vapor transport across the Equator shows the strongest response for the SH winter (boreal summer) Hadley cell over the Pacific Ocean due to an enhanced cross-equatorial SST gradient in the tropical Pacific during the early Holocene and the early Eemian. The orbitally-induced increase of the cross-equatorial insolation gradient in the tropical Pacific leads to a strengthening (weakening) of the wind speed and enhanced (reduced) evaporative cooling over the southern (northern) tropical Pacific, which reinforces the initial radiatively-forced meridional SST gradient change. The increased cross-equatorial insolation gradient in combination with the strong wind-evaporation-SST feedback and changing humidity are important mechanisms to enhance the SH winter Hadley circulation response to orbital forcing. Key Points: Intensification of the SH winter Hadley cell for the early Holocene and Eemian. Walker circulation's rising branch is shifted westward towards the Indian Ocean. WES feedback plays key role in intensification of the Hadley circulation

    Military expenditures and shadow economy in the Baltic States: Is there a link?

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    The main goal of our paper is to determine the existence of a link between government (military) expenditures and the shadow economy in the Baltic States. The empirical investigation is done over the years 2003-2014 for Estonia, Latvia and Lithuania. We showed that there is a highly statistically significant positive dependence between the size of the shadow economy and military expenditures in the Baltic States. Our conclusion is that higher military expenditures indeed lead to a higher shadow economy and this result is robust to different model specifications. In order to demonstrate the importance of our highly statistically significant results we undertook a simulation where we calculated how much the size of the shadow economy would increase if the size of military expenditure as a percentage of GDP doubled: In Estonia such an expansion would have led to an increase in the size of the shadow economy from 27.1% to 30.1%, in Latvia from 24.7% to 26.1% and in Lithuania from 27.1% to 28.4% in 2014

    Application of a sensitive collection heuristic for very large protein families: Evolutionary relationship between adipose triglyceride lipase (ATGL) and classic mammalian lipases

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    BACKGROUND: Manually finding subtle yet statistically significant links to distantly related homologues becomes practically impossible for very populated protein families due to the sheer number of similarity searches to be invoked and analyzed. The unclear evolutionary relationship between classical mammalian lipases and the recently discovered human adipose triglyceride lipase (ATGL; a patatin family member) is an exemplary case for such a problem. RESULTS: We describe an unsupervised, sensitive sequence segment collection heuristic suitable for assembling very large protein families. It is based on fan-like expanding, iterative database searches. To prevent inclusion of unrelated hits, additional criteria are introduced: minimal alignment length and overlap with starting sequence segments, finding starting sequences in reciprocal searches, automated filtering for compositional bias and repetitive patterns. This heuristic was implemented as FAMILYSEARCHER in the ANNIE sequence analysis environment and applied to search for protein links between the classical lipase family and the patatin-like group. CONCLUSION: The FAMILYSEARCHER is an efficient tool for tracing distant evolutionary relationships involving large protein families. Although classical lipases and ATGL have no obvious sequence similarity and differ with regard to fold and catalytic mechanism, homology links detected with FAMILYSEARCHER show that they are evolutionarily related. The conserved sequence parts can be narrowed down to an ancestral core module consisting of three β-strands, one α-helix and a turn containing the typical nucleophilic serine. Moreover, this ancestral module also appears in numerous enzymes with various substrate specificities, but that critically rely on nucleophilic attack mechanisms

    Religião, política e liberdade: contribuições de Baruch Espinoza

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    Há décadas existem discussões sobre a separação entre religião e política e religião e esfera pública que focam sobretudo nos limites desse mito moderno e nas possibilidades de coexistência dessas esferas no mundo contemporâneo. No entanto, pouco se explora sobre origens filosóficas de visões intermediárias, que concebem a inevitável influência do universo sagrado no mundo profano, mas questiona os limites plausíveis que a religião deve construir para garantir paz, direitos fundamentais e liberdades mais amplas. Este ensaio rastreia tais origens filosóficas no pensamento de Baruch Espinoza e o contrasta com a utopia liberal restrita de John Locke, amplamente propagada, mas irrealizável em tempos de separação apenas formal entre religião e política, objetivando resgatar discussões relevantes acerca do debate religião-política para nossos dilemas contemporâneos
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