5,776 research outputs found

    Time-dependent Gross-Pitaevskii equation for composite bosons as the strong-coupling limit of the fermionic BCS-RPA approximation

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    The linear response to a space- and time-dependent external disturbance of a system of dilute condensed composite bosons at zero temperature, as obtained from the linearized version of the time-dependent Gross-Pitaevskii equation, is shown to result also from the strong-coupling limit of the time-dependent BCS (or broken-symmetry RPA) approximation for the constituent fermions subject to the same external disturbance. In this way, it is possible to connect excited-state properties of the bosonic and fermionic systems by placing the Gross-Pitaevskii equation in perspective with the corresponding fermionic approximationsComment: 4 pages, 1 figur

    In Situ Treatment of Contaminated Water Environments: The Experiment of the Arsenale Vecchio, Venice Lagoon, Italy

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    We report on the results of an experiment of in situ bioremediation by forced aeration, carried out in the Arsenale Vecchio shipyard dock basin of the Venice Lagoon, Italy. The experimental area is characterized by its limited size and reduced boat traffic. The forced aeration technique chosen for the oxygenation of the highly polluted bottom sediments and of the water column above does not obstruct harbor activities and is unique due to its innovative use of a system of porous pipes laid on the bottom sediments. The general recovery of the polluted shipyard dock basin resulted in the documented return of small fish to the area as an indication of a less polluted environment. Most important the bioremediation of the water body above the bottom sediment favours, with time, the formation of a clean natural sediment capping over the bottom contaminated sediments. Post-experiment control after fifteen months of aeration with no extra oxygen added, shows the presence of clean light grey sediments with no foul septic smell, deposited over the polluted bottom sediments. The experiment has indicated that oxygenation by porous pipe forced aeration could represent a cost effective and environmentally feasible way for the recovery of shallow marine and fresh water systems, in situations where other techniques may not be economically and/or environmentally feasible

    Momentum distribution of a trapped Fermi gas with large scattering length

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    Using a scattering length parametrization of the BCS-BEC crossover as well as the local density approximation for the density profile, we calculate the momentum distribution of a harmonically trapped atomic Fermi gas at zero temperature. Various interaction regimes are considered, including the BCS phase, the unitarity limit and the molecular regime. We show that the relevant parameter which characterizes the crossover is given by the dimensionless combination N1/6a/ahoN^{1/6}a/a_{ho}, where NN is the number of atoms, aa is the scattering length and ahoa_{ho} is the oscillator length. The width of the momentum distribution is shown to depend in a crucial way on the value and sign of this parameter. Our predictions can be relevant for experiments on ultracold atomic Fermi gases near a Feshbach resonance.Comment: 6 pages, 2 figures. Submitted to Phys. Rev. A. Added reference

    Examination and evaluation of a coastal environment contamination at a formed shooting area.

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    In the recent past a very beautiful area along the interior coastal environment of Venice lagoon was used as a Clay Pigeon Shooting for a wide period. The sport of Clay Pigeon Shooting involves using a shotgun to shoot at and break a circular flying target made from a fragile material. It is released from a trap positioned in front of, or at the back of, a shooter; then, a typical target flight area characterizes each shooting site, where, in time, pellets (leadshot), shot cartridge, clay pigeon fragments and generic ammunition residues are found. So, in a brackish water contest soil/sediment treatment, waste removal and potential re-use are extremely delicate processes. The first step of our work was investigate if heavy metal (Pb, As and Sb) release and following leaching event occurred. Therefore, soil/sediment profiles in three hot sites of the target flight area has been performed and metal’s total and bioavailable fraction has been investigated. As well, grassy layer coating the sites and organisms living into has been picked, in order to verify a potential uptake and bioaccumulation

    Climate Change and Childhood Respiratory Health: A Call to Action for Paediatricians

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    Climate change (CC) is one of the main contributors to health emergencies worldwide. CC appears to be closely interrelated with air pollution, as some pollutants like carbon dioxide (CO2), nitrogen oxides (NOx) and black carbon are naturally occurring greenhouse gases. Air pollution may enhance the allergenicity of some plants and, also, has an adverse effect on respiratory health. Children are a uniquely vulnerable group that suffers disproportionately from CC burden. The increasing global warming related to CC has a big impact on plants' lifecycles, with earlier and longer pollen seasons, as well as higher pollen production, putting children affected by asthma and allergic rhinitis at risk for exacerbations. Extreme weather events may play a role too, not only in the exacerbations of allergic respiratory diseases but, also, in favouring respiratory infections. Even though paediatricians are already seeing the impacts of CC on their patients, their knowledge about CC-related health outcomes with specific regards to children's respiratory health is incomplete. This advocates for paediatricians' increased awareness and a better understanding of the CC impact on children's respiratory health. Having a special responsibility for children, paediatricians should actively be involved in policies aimed to protect the next generation from CC-related adverse health effects. Hence, there is an urgent need for them to take action and successfully educate families about CC issues. This paper aims at reviewing the evidence of CC-related environmental factors such as temperature, humidity, rainfall and extreme events on respiratory allergic diseases and respiratory infections in children and proposing specific actionable items for paediatricians to deal with CC-related health issues in their clinical practice

    Weakly Interacting, Dilute Bose Gases in 2D

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    This article surveys a number of theoretical problems and open questions in the field of two-dimensional dilute Bose gases with weak repulsive interactions. In contrast to three dimensions, in two dimensions the formation of long-range order is prohibited by the Bogoliubov-Hohenberg theorem, and Bose-Einstein condensation is not expected to be realized. Nevertheless, first experimental indications supporting the formation of the condensate in low dimensional systems have been recently obtained. This unexpected behaviour appears to be due to the non-uniformity, introduced into a system by the external trapping potential. Theoretical predictions, made for homogeneous systems, require therefore careful reexamination. We survey a number of popular theoretical treatments of the dilute weakly interacting Bose gas and discuss their regions of applicability. The possibility of Bose-Einstein condensation in a two-dimensional gas, the validity of perturbative t-matrix approximation and diluteness condition are issues that we discuss in detail.Comment: Survey, 25 pages RMP style, revised version, refs added, some changes made, accepted for publication in Rev. Mod. Phy

    An alternative to Neutral Red as a dye for environmental contaminant biomonitoring.

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    Many methods have been proposed for evaluating of toxic compound presence in water and then to assess the risks to both humans and animals. A common standards procedure for the measuring of contaminant toxicity strength in sea water organisms utilizes the response of a dye (Neutral Red), which accumulates in the acidic vescicles of biological sensors (i.e. Mollusc). When marine Mollusc such as mussels are exposed to pollutants, one of the characteristic pathological alterations is a decreased integrity in the lysosomal membrane. In this work we propose a comparison with the responses obtained with another dye, Acridine Orange. The results show that the response of Acridine Orange is linear in the whole operative pH range (i.e., between pH 4 and 7,4), while Neutral Red is insensitive between pH 6 and 7,4. In addition, Neutral Red shows a protonophore behaviour. We propose therefore that the use of Acridine Orange is preferred to that of Neutral Red, as well that Acridine Orange should be alternative to Neutral Red for the monitoring of stressing environment contaminants by means of biological sensors

    Data acquisition software for the CMS strip tracker

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    The CMS silicon strip tracker, providing a sensitive area of approximately 200 m2 and comprising 10 million readout channels, has recently been completed at the tracker integration facility at CERN. The strip tracker community is currently working to develop and integrate the online and offline software frameworks, known as XDAQ and CMSSW respectively, for the purposes of data acquisition and detector commissioning and monitoring. Recent developments have seen the integration of many new services and tools within the online data acquisition system, such as event building, online distributed analysis, an online monitoring framework, and data storage management. We review the various software components that comprise the strip tracker data acquisition system, the software architectures used for stand-alone and global data-taking modes. Our experiences in commissioning and operating one of the largest ever silicon micro-strip tracking systems are also reviewed
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