2,286 research outputs found

    Linear Ramps of Interaction in the Fermionic Hubbard Model

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    We study the out of equilibrium dynamics of the Fermionic Hubbard Model induced by a linear ramp of the repulsive interaction UU from the metallic state through the Mott transition. To this extent we use a time dependent Gutzwiller variational method and complement this analysis with the inclusion of quantum fluctuations at the leading order, in the framework of a Z2Z_2 slave spin theory. We discuss the dynamics during the ramp and the issue of adiabaticity through the scaling of the excitation energy with the ramp duration Ď„\tau. In addition, we study the dynamics for times scales longer than the ramp time, when the system is again isolated and the total energy conserved. We establish the existence of a dynamical phase transition analogous to the one present in the sudden quench case and discuss its properties as a function of final interaction and ramp duration. Finally we discuss the role of quantum fluctuations on the mean field dynamics for both long ramps, where spin wave theory is sufficient, and for very short ramps, where a self consistent treatment of quantum fluctuations is required in order to obtain relaxation.Comment: v2: 19 pages, 14 figures, published versio

    Bayesian event tree for eruption forecasting (BET_EF) at Vesuvius, Italy: a retrospective forward application to the 1631 eruption

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    Reliable forecasting of the next eruption at Vesuvius is the main scientific factor in defining effective strategies to reduce volcanic risk in one of the most dangerous volcanic areas of the world. In this paper, we apply a recently developed probabilistic code for eruption forecasting to new and independent historical data related to the pre-eruptive phase of the 1631 eruption. The results obtained point out three main issues: (1) the importance of “cold” historical data (according to Guidoboni 2008) related to pre-eruptive phases for evaluating forecasting tools and possibly refining them; (2) the BET_EF code implemented for Vesuvius would have forecasted the 1631 eruption satisfactorily, marking different stages of the pre-eruptive phase; (3) the code shows that pre-eruptive signals that significantly increase the probability of eruption were likely detected more than 2 months before the event

    Bayesian Event Tree for Eruption Forecasting (BET_EF) at Vesuvius, Italy: a retrospective forward application to the 1631 eruption

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    Reliable forecasting of the next eruption at Vesuvius is the main scientific ingredient to define effective strategies to reduce volcanic risk in one of the most dangerous volcanic areas around the world. In this paper, we apply a recently developed probabilistic code for eruption forecasting to new and independent historical data related to the pre-eruptive phase of the 1631 eruption. The results obtained point out three main issues: 1) the importance of “cold” historical data (according to Guidoboni 2008) related to pre-eruptive phases for evaluating forecasting tools and possibly refining them; 2) the BET_EF code implemented for Vesuvius would have forecast the 1631 eruption satisfactorily, marking different stages of the pre-eruptive phase; 3) the code shows that pre-eruptive signals that significantly increase the probability of eruption were likely detected more than two months before the even

    Electrophysiological characterization of contact sites in brain mitochondria.

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    From morphological and biochemical studies it has been recognized that the regions where the outer and inner membranes of mitochondria come in close contact (contact sites) can be the route mechanism through which mitochondria interact directly with the cytoplasm. We have studied these regions electrophysiologically with the patch clamp technique, with the aim of understanding if this direct interaction is mediated by high conductance ion channels similar to the channel already detected in the inner membrane of mitochondria (Sorgato M. C., Keller, B. U., and StĂĽhmer, W. (1987) Nature 330, 498-500). Contact sites isolated from rat brain mitochondria were thus incorporated into liposomes subsequently enlarged sufficiently to be patch clamped. This study shows that these particular fractions contain ion channels with conductances ranging from approximately 5 picosiemens to 1 nanosiemens (in symmetrical 150 mM KCl). Most of these channels are not voltage-dependent and can be open at physiological potentials sustained by respiring mitochondria. The lack of voltage sensitivity seems not to be the outcome of methodological artifacts, as voltage-gated channels are detected in giant liposomes containing either the outer mitochondrial membrane or a partially purified fraction of the inner mitochondrial membrane. These data therefore indicate that channels present in mitochondrial contact sites have properties which render them amenable to perform several of the functions hypothesized for these regions, particularly that of translocating macromolecules from the cytoplasm to the matrix of mitochondria

    Innes: Security Bonds

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    Risk in society is a pertinent concept of late modernity. Most elements of our social and interpersonal lives are in some way linked to concerns about safety, security and fear of harm. As a consequence, we spend a great deal of time engaged in emotional, physical and economic processes that facilitate our safety. Whether this be through purchasing anti-theft devices, or subscribing to self-defense training courses; participating in neighbourhood-watch schemes or altering our behavior to prevent susceptibility to victimization, all demonstrate an inherent pre-occupation with risk and perceived danger. The work presented in this paper offers an in-depth socio-criminological analysis focusing on the issue of citizens insecurity, and proposes an original interpretative paradigm emerging from findings on the INNES (Intimate Neighborhood Strengthening) European Project. A presentation of the idiographic and nomothetic motivations and conditions influencing and predicting social fears and insecurities over the last two decades is discussed, with the presentation of the new interpretative model, 'Social Cobweb Theory'. This model focuses on solidarity and on the strengthening of intimate neighborhood bonds and argues that these aforementioned concepts function as an effective approach in lowering citizens' perceptions of individual insecurities and risk

    Tingkat Pencemaran Udara Co Akibat Lalu Lintas Dengan Model Prediksi Polusi Udara Skala Mikro

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    Pencemaran udara memberi dampak negatif bagi kesehatan manusia akibat polutan yang dikeluarkan oleh kendaraan bermotor. Dari beberapa jenis polutan yang dihasilkan, CO merupakan salah satu polutan yangpaling banyak yang dikeluarkan oleh kendaraan bermotor. Tujuan dari penelitian ini adalah untuk mengetahui besarnya konsentrasi CO yang dikeluarkan oleh lalu lintas kendaraan bermotor khususnya di ruas jalan Sam Ratulangi Manado. Metode yang digunakan dalam penelitian ini yaitu melalui survei dan observasi lapangan.Analisis data dilakukan dengan menggunakan pemodelan polusi udara skala mikro. Untuk menentukan persentase CO yang ditimbulkan oleh lalu lintas yaitu dengan membandingkan hasil perhitungan pemodelandengan hasil pengukuran udara ambient. Hasil penelitian menunjukan bahwa besarnya konsentrasi gas CO akibat lalulintas di ruas jalan Sam Ratulangi Manado berkisar 7242.99 ÎĽg/m3 sampai 15577,07 ÎĽg/m3, belum melampaui ambang batas baku mutu udara ambient nasional. Dari jumlah polutan CO yang ada di udara, 80,22% - 92,00% berasal dari kendaraan bermotor

    Blood microbiome: A new marker of gut microbial population in dogs?

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    The characterization of the microbial population in different compartments of the organism, such as the gastrointestinal tract, is now possible thanks to the use of high-throughput DNA sequencing technique. Several studies in the companion animals field have already investigated the fecal microbiome in healthy or sick subjects; however, the methodologies used in the different laboratories and the limited number of animals recruited in each experiment do not allow a straight comparison among published results. Previously, our research focused on the characterization of the microbial taxa variability in 340 fecal samples from 132 healthy dogs, collected serially from several in-house experiments. The results supported the responsiveness of microbiota to dietary and sex factors and allowed us to cluster dogs with high accuracy. For the present study, intestinal and blood microbiota of healthy dogs from different breeds, genders, ages and food habits were collected, with three principal aims: firstly, to confirm the results of our previous study regarding the fecal microbiome affected by the different type of diet; secondly, to investigate the existence of a blood microbial population, even in heathy subjects; and thirdly, to seek for a possible connection between the fecal and the blood microbiota. Limited researches have been published on blood microbiota in humans, and this is the first evidence of the presence of a bacterial population in the blood of dogs. Moreover, gut and blood microbiota can discriminate the animals by factors such as diet, suggesting some relationship between them. These preliminary results make us believe in the use of the blood microbiome for diagnostic purposes, such as researching and preventing gut inflammatory diseases
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