444 research outputs found

    Variational methods with coupled Gaussian functions for Bose-Einstein condensates with long-range interactions. II. Applications

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    Bose-Einstein condensates with an attractive 1/r interaction and with dipole-dipole interaction are investigated in the framework of the Gaussian variational ansatz introduced by S. Rau, J. Main, and G. Wunner [Phys. Rev. A, submitted]. We demonstrate that the method of coupled Gaussian wave packets is a full-fledged alternative to direct numerical solutions of the Gross-Pitaevskii equation, or even superior in that coupled Gaussians are capable of producing both, stable and unstable states of the Gross-Pitaevskii equation, and thus of giving access to yet unexplored regions of the space of solutions of the Gross-Pitaevskii equation. As an alternative to numerical solutions of the Bogoliubov-de Gennes equations, the stability of the stationary condensate wave functions is investigated by analyzing the stability properties of the dynamical equations of motion for the Gaussian variational parameters in the local vicinity of the stationary fixed points. For blood-cell-shaped dipolar condensates it is shown that on the route to collapse the condensate passes through a pitchfork bifurcation, where the ground state itself turns unstable, before it finally vanishes in a tangent bifurcation.Comment: 14 pages, 14 figures, submitted to Phys. Rev. A, some equations correcte

    Directed Chaotic Transport in Hamiltonian Ratchets

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    We present a comprehensive account of directed transport in one-dimensional Hamiltonian systems with spatial and temporal periodicity. They can be considered as Hamiltonian ratchets in the sense that ensembles of particles can show directed ballistic transport in the absence of an average force. We discuss general conditions for such directed transport, like a mixed classical phase space, and elucidate a sum rule that relates the contributions of different phase-space components to transport with each other. We show that regular ratchet transport can be directed against an external potential gradient while chaotic ballistic transport is restricted to unbiased systems. For quantized Hamiltonian ratchets we study transport in terms of the evolution of wave packets and derive a semiclassical expression for the distribution of level velocities which encode the quantum transport in the Floquet band spectra. We discuss the role of dynamical tunneling between transporting islands and the chaotic sea and the breakdown of transport in quantum ratchets with broken spatial periodicity.Comment: 22 page

    Relationship Between Microbial Growth and Hydraulic Properties at the Sub-Pore Scale

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    Accumulation of microbial biomass and its influence on porous media flow were investigated under saturated flow conditions. Microfluidic experiments were performed with model organisms, and their accumulation was observed in the pore space and on the sub-pore scale. Time-lapse optical imaging revealed different modes of biomass accumulation through primary colonization, secondary growth, and filtration events, showing the formation of preferential flow pathways in the flooding domain as result of the increasing interstitial velocity. Navier–Stokes–Brinkmann flow simulations were performed on the segmented images—a digital-twin approach—considering locally accumulated biomass as impermeable or permeable based on optical biomass density. By comparing simulation results and the experimental responses, it was shown that accumulated biomass can be considered as a permeable medium. The average intra-biomass permeability was determined to be 500 ± 200 mD, which is more than a factor of 10 larger than previously assumed in modeling studies. These findings have substantial consequences: (1) a remaining interstitial permeability, as a result of the observed channel formation and the intra-biomass permeability, and (2) a potential advective nutrient supply, which can be considered more efficient than a purely diffusive supply. The second point may lead to higher metabolic activity and substrate conversion rates which is of particular interest for geobiotechnological applications.publishedVersio

    Progettazione e realizzazione di un sistema di refertazione specialistico-ambulatoriale

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    Come per tutte le strutture che erogano servizi sanitari, lo scopo di un ospedale è quello di soddisfare il bisogno di cure degli assistiti, nel rispetto della loro persona, offrendo un servizio di qualità. Nel caso di strutture private o enti ecclesiastici, che non sono supportate da finanziamenti dello Stato, l’attività di assistenza è inoltre organizzata in maniera tale da ottimizzare i costi, cercare di rendere sempre più efficienti le risorse a disposizione e quindi ridurre gli sprechi. I sistemi informativi ospedalieri hanno certamente contribuito al supporto delle operazioni svolte nei percorsi assistenziali e della comunicazione di informazioni cliniche dei pazienti all'interno della struttura tra il personale sanitario. Attualmente anche il web può essere considerata una risorsa e come tale può essere sfruttata per migliorare il servizio offerto, creare valore per i pazienti e ridurre lo spreco di risorse. Proprio grazie a questa consapevolezza, l’Agenzia per l’Italia Digitale ha stabilito un piano di intervento per promuovere le tecnologie ICT a supporto della pubblica amministrazione, e quindi anche in ambito sanitario. Il lavoro di questa tesi è stato svolto, in convenzione con l’Università di Pisa, presso l'Ospedale Card. G. Panico di Tricase, un ente ecclesiastico classificato come Azienda Ospedaliera, desideroso di allinearsi agli obiettivi proposti da tali piani di intervento. La prima fase si è focalizzata su una panoramica delle azioni previste dall’AgID e sull’analisi del contatto aziendale e in particolare del SIO esistente a supporto dei processi nell’assistenza ai pazienti. Da tale analisi sono emerse delle criticità nella gestione attuale dei dati clinici ed è stato quindi proposto di intervenire realizzando un dossier sanitario digitale, prerogativa assoluta per contribuire a realizzare il Fascicolo Sanitario Elettronico. Dopo aver definito l’oggetto dell’intervento, si è passati ad una fase di analisi del contesto di lavoro, che ha incluso lo studio dei requisiti funzionali e non funzionali da soddisfare, delle risorse a disposizione, dei sistemi esistenti coi quali interagirà, degli standard internazionali usati in tale ambito, dei vincoli tecnici e giuridici, delle architetture impiegate in questo settore. Sulla base di tali analisi e ricerche, e considerate le esigenze aziendali esposte dalla Direzione Sanitaria e dal personale medico coinvolto, è stato possibile procedere alla progettazione dell’applicazione e del database a supporto; per poi completare il lavoro con lo sviluppo del progetto tramite strumenti validi e consolidati. Il frutto del lavoro di tesi è rappresentato da un'applicazione java enterprise, basata su web services, organizzata secondo il pattern architetturale MVVM col supporto del framework open-source ZK. Il lavoro svolto è strutturato in più capitoli, i quali ripercorrono le fasi di analisi, progettazione e sviluppo sopra descritte, e si conclude con alcune considerazioni finali su impieghi futuri e possibili estensioni dell'applicazione creata

    Carbon Monitoring System Flux Estimation and Attribution: Impact of ACOS-GOSAT X(CO2) Sampling on the Inference of Terrestrial Biospheric Sources and Sinks

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    Using an Observing System Simulation Experiment (OSSE), we investigate the impact of JAXA Greenhouse gases Observing SATellite 'IBUKI' (GOSAT) sampling on the estimation of terrestrial biospheric flux with the NASA Carbon Monitoring System Flux (CMS-Flux) estimation and attribution strategy. The simulated observations in the OSSE use the actual column carbon dioxide (X(CO2)) b2.9 retrieval sensitivity and quality control for the year 2010 processed through the Atmospheric CO2 Observations from Space algorithm. CMS-Flux is a variational inversion system that uses the GEOS-Chem forward and adjoint model forced by a suite of observationally constrained fluxes from ocean, land and anthropogenic models. We investigate the impact of GOSAT sampling on flux estimation in two aspects: 1) random error uncertainty reduction and 2) the global and regional bias in posterior flux resulted from the spatiotemporally biased GOSAT sampling. Based on Monte Carlo calculations, we find that global average flux uncertainty reduction ranges from 25% in September to 60% in July. When aggregated to the 11 land regions designated by the phase 3 of the Atmospheric Tracer Transport Model Intercomparison Project, the annual mean uncertainty reduction ranges from 10% over North American boreal to 38% over South American temperate, which is driven by observational coverage and the magnitude of prior flux uncertainty. The uncertainty reduction over the South American tropical region is 30%, even with sparse observation coverage. We show that this reduction results from the large prior flux uncertainty and the impact of non-local observations. Given the assumed prior error statistics, the degree of freedom for signal is approx.1132 for 1-yr of the 74 055 GOSAT X(CO2) observations, which indicates that GOSAT provides approx.1132 independent pieces of information about surface fluxes. We quantify the impact of GOSAT's spatiotemporally sampling on the posterior flux, and find that a 0.7 gigatons of carbon bias in the global annual posterior flux resulted from the seasonally and diurnally biased sampling when using a diagonal prior flux error covariance

    Quantifying the Observability of CO2 Flux Uncertainty in Atmospheric CO2 Records Using Products from Nasa's Carbon Monitoring Flux Pilot Project

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    NASAs Carbon Monitoring System (CMS) Flux Pilot Project (FPP) was designed to better understand contemporary carbon fluxes by bringing together state-of-the art models with remote sensing datasets. Here we report on simulations using NASAs Goddard Earth Observing System Model, version 5 (GEOS-5) which was used to evaluate the consistency of two different sets of observationally constrained land and ocean fluxes with atmospheric CO2 records. Despite the strong data constraint, the average difference in annual terrestrial biosphere flux between the two land (NASA Ames CASA and CASA-GFED) models is 1.7 Pg C for 2009-2010. Ocean models (NOBM and ECCO2-Darwin) differ by 35 in their global estimates of carbon flux with particularly strong disagreement in high latitudes. Based upon combinations of terrestrial and ocean fluxes, GEOS-5 reasonably simulated the seasonal cycle observed at northern hemisphere surface sites and by the Greenhouse gases Observing SATellite (GOSAT) while the model struggled to simulate the seasonal cycle at southern hemisphere surface locations. Though GEOS-5 was able to reasonably reproduce the patterns of XCO2 observed by GOSAT, it struggled to reproduce these aspects of AIRS observations. Despite large differences between land and ocean flux estimates, resulting differences in atmospheric mixing ratio were small, typically less than 5 ppmv at the surface and 3 ppmv in the XCO2 column. A statistical analysis based on the variability of observations shows that flux differences of these magnitudes are difficult to distinguish from natural variability, regardless of measurement platform

    Dystonia Linked to EIF4A2 Haploinsufficiency: A Disorder of Protein Translation Dysfunction

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    Background: Protein synthesis is a tightly controlled process, involving a host of translation-initiation factors and microRNA-associated repressors. Variants in the translational regulator EIF2AK2 were first linked to neurodevelopmental-delay phenotypes, followed by their implication in dystonia. Recently, de novo variants in EIF4A2, encoding eukaryotic translation initiation factor 4A isoform 2 (eIF4A2), have been described in pediatric cases with developmental delay and intellectual disability. Objective: We sought to characterize the role of EIF4A2 variants in dystonic conditions. Methods: We undertook an unbiased search for likely deleterious variants in mutation-constrained genes among 1100 families studied with dystonia. Independent cohorts were screened for EIF4A2 variants. Western blotting and immunocytochemical studies were performed in patient-derived fibroblasts. Results: We report the discovery of a novel heterozygous EIF4A2 frameshift deletion (c.896_897del) in seven patients from two unrelated families. The disease was characterized by adolescence- to adulthood-onset dystonia with tremor. In patient-derived fibroblasts, eIF4A2 production amounted to only 50% of the normal quantity. Reduction of eIF4A2 was associated with abnormally increased levels of IMP1, a target of Ccr4-Not, the complex that interacts with eIF4A2 to mediate microRNA-dependent translational repression. By complementing the analyses with fibroblasts bearing EIF4A2 biallelic mutations, we established a correlation between IMP1 expression alterations and eIF4A2 functional dosage. Moreover, eIF4A2 and Ccr4-Not displayed significantly diminished colocalization in dystonia patient cells. Review of international databases identified EIF4A2 deletion variants (c.470_472del, c.1144_1145del) in another two dystonia-affected pedigrees. Conclusions: Our findings demonstrate that EIF4A2 haploinsufficiency underlies a previously unrecognized dominant dystonia-tremor syndrome. The data imply that translational deregulation is more broadly linked to both early neurodevelopmental phenotypes and later-onset dystonic conditions. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society

    Familie - Generation - Institution. Generationenkonzepte in der Vormoderne

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    Dieser Band versammelt Beiträge zu Generationenbeziehungen und Generationenkonzepten in der Vormoderne, die auf eine Tagung des DFG-Graduiertenkollegs 'Generationenbewusstsein und Generationenkonflikte in Antike und Mittelalter' in Bamberg zurückgehen. Die behandelten Untersuchungsgegenstände reichen von den antiken Diadochenreichen über die ottonische Königsfamilie des 10. und 11. Jahrhunderts bis zum frühneuzeitlichen Landadel Westfalens. Dabei werden historische, literaturwissenschaftliche und soziologische Fragestellungen aufgegriffen, um den Erkenntniswert des Konzepts 'Generation' interdisziplinär zu diskutieren.This volume brings together contributions on generational relations and concepts of generation in Early Modernity given on the occasion of a conference organized at Bamberg by the Research Training Group of the German Research Foundation (DFG) 'Generational Awareness and Generational Conflicts in Antiquity and the Middle Ages'. The topics ranged from the ancient Diadoch kingdoms to the history of the Ottonian royal family of the 10th and 11th centuries and the early modern landed gentry in Westfalia. Addressing questions from historical, literary and social studies the validity of the concept of 'generation' was discussed among scholars and students from a variety of disciplines
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