17,053 research outputs found

    Relations Between Central Black Hole Mass and Total Galaxy Stellar Mass in the Local Universe

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    Scaling relations between central black hole (BH) mass and host galaxy properties are of fundamental importance to studies of BH and galaxy evolution throughout cosmic time. Here we investigate the relationship between BH mass and host galaxy total stellar mass using a sample of 262 broad-line active galactic nuclei (AGN) in the nearby Universe (z < 0.055), as well as 79 galaxies with dynamical BH masses. The vast majority of our AGN sample is constructed using Sloan Digital Sky Survey spectroscopy and searching for Seyfert-like narrow-line ratios and broad H-alpha emission. BH masses are estimated using standard virial techniques. We also include a small number of dwarf galaxies with total stellar masses M_stellar < 10^9.5 Msun and a sub-sample of the reverberation-mapped AGNs. Total stellar masses of all 341 galaxies are calculated in the most consistent manner feasible using color-dependent mass-to-light ratios. We find a clear correlation between BH mass and total stellar mass for the AGN host galaxies, with M_BH proportional to M_stellar, similar to that of early-type galaxies with dynamically-detected BHs. However, the relation defined by the AGNs has a normalization that is lower by more than an order of magnitude, with a BH-to-total stellar mass fraction of M_BH/M_stellar ~ 0.025% across the stellar mass range 10^8 < M_stellar/Msun < 10^12. This result has significant implications for studies at high redshift and cosmological simulations in which stellar bulges cannot be resolved.Comment: Accepted for publication in the Astrophysical Journal. 15 pages, 12 figure

    Enhancing scarce-resource language translation through pivot combinations

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    Chinese and Spanish are the most spoken languages in the world. However, there is not much research done in machine translation for this language pair. We experiment with the parallel Chinese-Spanish corpus (United Nations) to explore alternatives of SMT strategies which consist on using a pivot language. Particularly, two well-known alternatives are shown for pivoting: the cascade system and the pseudo-corpus. As Pivot language we use English, Arabic and French. Results show that English is the best pivot language between Chinese and Spanish. As a new strategy, we propose to perform a combination of the pivot strategies which is capable to highly outperform the direct translation strategy.Postprint (published version

    A feasibility study of wearable activity monitors for pre-adolescent school-age children.

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    IntroductionUnderstanding physical activity is key in the fight against childhood obesity. The objective of this study was to examine the feasibility of using certain wearable devices to measure physical activity among children.MethodsA qualitative study was conducted with 25 children aged 7 to 10 years to assess acceptability and compliance of wearable activity devices in this age group. During March through August 2012, children participated in a 4-week study of 3 accelerometer models and a heart rate monitor. Children were asked to use a different device each week for 7 consecutive days. Children and their parents completed structured interviews after using each device; they also completed a final exit interview.ResultsThe wrist-worn Polar Active was the device most preferred by children and was associated with the highest level of compliance. Devices that are comfortable to wear, fit properly, have engaging features, and are waterproof increase feasibility and are associated with higher levels of compliance.ConclusionThe wrist-worn device was the most feasible for measuring physical activity among children aged 7 to 10 years. These findings will inform researchers in selecting tools for measuring children's physical activity

    Simulation or cohort models? Continuous time simulation and discretized Markov models to estimate cost-effectiveness

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    The choice of model design for decision analytic models in cost-effectiveness analysis has been the subject of discussion. The current work addresses this issue by noting that, when time is to be explicitly modelled, we need to represent phenomena occurring in continuous time. Multistate models evaluated in continuous time might be used but closed form solutions of expected time in each state may not exist or may be difficult to obtain. Two approximations can then be used for costeffectiveness estimation: (1) simulation models, where continuous time estimates are obtained through Monte Carlo simulation, and (2) discretized models. This work draws recommendations on their use by showing that, when these alternative models can be applied, it is preferable to implement a cohort discretized model than a simulation model. Whilst the bias from the first can be minimized by reducing the cycle length, the second is inherently stochastic. Even though specialized literature advocates this framework, the current practice in economic evaluation is to define clinically meaningful cycle lengths for discretized models, disregarding potential biases.

    Contribution of agronomy to land management issues - A Comparison of five interdisciplinary PhD theses

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    An introductory literature review highlights the growing attention within the processes taking place at farming region and landscape scale beside the classical spatial scales at cultivated/experimental plot level. This recent evolution in agronomy finds its origin in newly emerging land management issues. Meanwhile, geography and other disciplines are stressing the need for a greater integration of multifunctional agricultural activities into the decision-making processes at the various levels of land management, such as provinces, municipalities or watersheds. This requires also that studies on farmland management include explicitly the different environmental and social contexts influencing farming activities. In this paper we aim to analyse how recent agronomic oriented research are facing and supporting various land management issues. We have compared five interdisciplinary PhD theses examining their definitions and methods of analysis for: the farming system, the local land management issues at stake, the spatial scale selected for the study, the stakeholders' involvement and the interaction with other disciplines. Common issues which emerged from this comparison are delivery of agro-environmental services, sustainable land management and landscape conservation. Multiple spatial levels were considered, which included at least one administrative unit of policy decision/implementation. Consequently, the explicit (re)definition of some agronomic concepts and methods was needed. Regarding the interdisciplinary framework, the theses have stressed the interactions among agronomy, geography and ecology. All theses aimed at delivering tools for decision-making support, mainly in the form of cartography. Nevertheless the participation of local stakeholders was generally included as a final step; herewith the settings of stakeholders' involvement were various. In conclusion, we discuss how the produced knowledge has enhanced the land management issues in local planning tools. On these bases, we stress finally the issues at stake to strengthen the roles and contributions of agronomic oriented education and research to agricultural land management and development. (Résumé d'auteur

    Analysis of Different Methodologies to Calculate Bouguer Gravity Anomalies in the Argentine Continental Margin

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    We have tested and used two methods to determine the Bouguer gravity anomaly in the area of the Argentine continental margin. The first method employs the relationship between the topography and gravity anomaly in the Fourier transform domain using Parker’s expression for different orders of expansion. The second method computes the complete Bouguer correction (Bullard A, B and C) with the Fortran code FA2BOUG2. The Bouguer slab correction (Bullard A), the curvature correction (Bullard B) and the terrain correction (Bullard C) are computed in several zones according to thedistances between the topography and the calculation point. In each zone, different approximations of the gravitationalattraction of rectangular or conic prisms are used according to the surrounding topography. Our calculations show that the anomaly generated by the fourth order in Parker’s expansion is actually compatible with the traditional Bouguer anomaly calculated with FA2BOUG, and that higher orders do not introduce significant changes. The comparison reveals that the difference between both methods in the Argentine continental margin has a quasi bimodal statistical distribution. The main disadvantage in using routines based on Parker's expansion is that an average value of the topography is needed for the calculation and, as the margin has an abrupt change of the topography in the continental slope area, it causes a bimodal distribution. It is worth noticing that, as expected, the most important differences between both methods are located over the continental slope both in complex structures such as part of the shared margin, as well as in isolated points where there are contributions from short wavelength or rugged topography.Fil: Pedraza de Marchi, Ana Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Ghidella, Marta E.. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Tocho, Claudia. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentin

    Modelling DNA Origami Self-Assembly at the Domain Level

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    We present a modelling framework, and basic model parameterization, for the study of DNA origami folding at the level of DNA domains. Our approach is explicitly kinetic and does not assume a specific folding pathway. The binding of each staple is associated with a free-energy change that depends on staple sequence, the possibility of coaxial stacking with neighbouring domains, and the entropic cost of constraining the scaffold by inserting staple crossovers. A rigorous thermodynamic model is difficult to implement as a result of the complex, multiply connected geometry of the scaffold: we present a solution to this problem for planar origami. Coaxial stacking and entropic terms, particularly when loop closure exponents are taken to be larger than those for ideal chains, introduce interactions between staples. These cooperative interactions lead to the prediction of sharp assembly transitions with notable hysteresis that are consistent with experimental observations. We show that the model reproduces the experimentally observed consequences of reducing staple concentration, accelerated cooling and absent staples. We also present a simpler methodology that gives consistent results and can be used to study a wider range of systems including non-planar origami

    Plagiarism detection using information retrieval and similarity measures based on image processing techniques

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    This paper describes the Barcelona Media Innovation Center participation in the 2nd International Competition on Plagiarism Detection. Particularly, our system focused on the external plagiarism detection task, which assumes the source documents are available. We present a two-step a approach. In the first step of our method, we build an information retrieval system based on Solr/Lucene, segmenting both suspicious and source documents into smaller texts.We perform a search based on bag-of-words which provides a first selection of potentially plagiarized texts. In the second step, each promising pair is further investigated. We implemented a sliding window approach that computes cosine distances between overlapping text segments from both the source and suspicious documents on a pair wise basis. As a result, a similarity matrix between text segments is obtained, which is smoothed by means of low-pass 2-D filtering. From the smoothed similarity matrix, plagiarized segments are identified by using image processing techniques. Our results were placed in the middle of the official ranking, which considered together two types of plagiarism: intrinsic and external.Postprint (published version

    Androgens and Hypertension in Men and Women: a Unifying View.

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    This review was designed to revaluate the androgen role on the mechanisms of hypertension and cardiovascular risks in both men and women. Sex steroids are involved in the regulation of blood pressure, but pathophysiological mechanism is not well understood. Androgens have an important effect on metabolism, adipose and endothelial cell function, and cardiovascular risk in both men and women. A focal point in this contest is represented by the possible gender-specific regulation of different tissues and in particular of the adipose cell. Available data confirm that androgen deficiency is linked to increased prevalence of hypertension and cardiovascular diseases. Adipocyte dysfunction seems to be the main involved mechanism. Androgen replacement reduces inflammation state in man, protecting by metabolic syndrome progression. In women, androgen excess has been considered as promoting factor of cardiovascular risk. However, recent data suggest that excessive androgen production has little effect per se in inducing hypertension in young women of reproductive age. Also in postmenopausal women, data on relative androgen excess and hypertension are missing, while adrenal androgen deficiency has been associated to increased mortality. RECENT FINDINGS: Molecular mechanisms linking androgen dysregulation to hypertension are almost Unknown, but they seem to be related to increased visceral fat, promoting a chronic inflammatory state through different mechanisms. One of these may involve the recruitment and over-activation of NF-kB, a ubiquitous transcription factor also expressed in adipose cells, where it may cause the production of cytokines and other immune factors. The NF-kB signalling pathway may also influence brown adipogenesis leading to the preferential enlargement of visceral adipocytes. Chronic inflammation and adipocyte dysfunction may alter endothelial function leading to hypertension. Both in men and in women, particularly in the post-menopausal period, hypoandrogenism seems to be a major determinant of the increased prevalence of hypertension. The relationship between androgen signalling and NF-kB might explain the pathophysiological mechanism leading to the development of endothelium dysfunction and hypertension
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