745 research outputs found

    The MESSy aerosol submodel MADE3 (v2.0b): description and a box model test

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    We introduce MADE3 (Modal Aerosol Dynamics model for Europe, adapted for global applications, 3rd generation; version: MADE3v2.0b), an aerosol dynamics submodel for application within the MESSy framework (Modular Earth Submodel System). MADE3 builds on the predecessor aerosol submodels MADE and MADE-in. Its main new features are the explicit representation of coarse mode particle interactions both with other particles and with condensable gases, and the inclusion of hydrochloric acid (HCl) / chloride (Cl) partitioning between the gas and condensed phases. The aerosol size distribution is represented in the new submodel as a superposition of nine lognormal modes: one for fully soluble particles, one for insoluble particles, and one for mixed particles in each of three size ranges (Aitken, accumulation, and coarse mode size ranges). <br><br> In order to assess the performance of MADE3 we compare it to its predecessor MADE and to the much more detailed particle-resolved aerosol model PartMC-MOSAIC in a box model simulation of an idealised marine boundary layer test case. MADE3 and MADE results are very similar, except in the coarse mode, where the aerosol is dominated by sea spray particles. Cl is reduced in MADE3 with respect to MADE due to the HCl / Cl partitioning that leads to Cl removal from the sea spray aerosol in our test case. Additionally, the aerosol nitrate concentration is higher in MADE3 due to the condensation of nitric acid on coarse mode particles. MADE3 and PartMC-MOSAIC show substantial differences in the fine particle size distributions (sizes &lesssim; 2 ÎĽm) that could be relevant when simulating climate effects on a global scale. Nevertheless, the agreement between MADE3 and PartMC-MOSAIC is very good when it comes to coarse particle size distributions (sizes &gtrsim; 2 ÎĽm), and also in terms of aerosol composition. Considering these results and the well-established ability of MADE in reproducing observed aerosol loadings and composition, MADE3 seems suitable for application within a global model

    Generalization of Dirac Non-Linear Electrodynamics, and Spinning Charged Particles

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    In this note we generalized the Dirac non-linear electrodynamics, by introducing two potentials (namely, the vector potential A and the pseudo-vector potential gamma^5 B of the electromagnetic theory with charges and magnetic monopoles) and by imposing the pseudoscalar part of the product omega.omega* to be zero, with omega = A + gamma^5 B. We show that the field equations of such a theory possess a soliton-like solution which can represent a priori a "charged particle", since it is endowed with a Coulomb field plus the field of a magnetic dipole. The rest energy of the soliton is finite, and the angular momentum stored in its electromagnetic field can be identified --for suitable choices of the parameters-- with the spin of the charged particle. Thus this approach seems to yield a classical model for the charged (spinning) particle, which does not meet the problems met by earlier attempts in the same direction.Comment: standard LaTeX file; 16 pages; it is a corrected version of a paper appeared in Found. Phys. (issue in honour of A.O.Barut) 23 (1993) 46

    A short-term comparison of wheat straw and poplar wood chips used as litter in tiestalls on hygiene, milk, and behavior of lactating dairy cows

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    A short-term study was conducted to compare the effect of using poplar wood chips (PWC) instead of wheat straw (WS) litter in dairy cows. A total of 38 lactating Holstein cows (204 ± 119 days in milk, 26.9 ± 6.5 kg of milk yield [MY]) were housed in a tiestall farm for a 10-d trial including 5 d of adaptation followed by 5 sampling days (from d 5 to 10). Cows were divided into 2 homogeneous groups: one group was bedded with WS, and the second with PWC. Both litter materials were provided in the amount of 7 kg/stall per d. Each group was composed of 3 subgroups of 6 or 7 cows; the subgroups were physically separated along the feeding line by wooden boards. During the sampling days, fecal composition, used litter composition, and bacterial count (Clostridium spp., Salmonella spp., Escherichia coli, Lactobacillus, and total bacterial count) were analyzed by subgroup twice a day. On d 1 and from d 5 to 10, udder hygiene score and cow cleanliness score were also evaluated individually twice a day. Meanwhile MY, milk hygiene (total bacterial count [TBC], coliform bacterial count [CBC], and spore-forming unit [SFU]) and quality were measured and analyzed from 9 animals per group. Moreover, individual animal behavior (body position and behavioral traits) and subgroup dry matter intake were measured on d 9 and 10. Fecal dry matter did not differ between groups, PWC had the lowest used litter moisture and N content favoring the highest clean cow frequency, but also gave rise to the greatest used litter microbial contamination. The MY, milk quality, TBC, SFU, and CBC were similar. The lying behavior frequency was similar between groups. However, the PWC group showed the lowest sleeping frequency, the highest frequency of other behaviors (including discomfort signs), and the lowest dry matter intake. However, despite this apparent reduction in cow comfort, no biologically important differences were observed in this short-term study between cows on PWC and WS in milk production or hygiene

    Monte-Carlo calculation of longitudinal and transverse resistivities in a model Type-II superconductor

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    We study the effect of a transport current on the vortex-line lattice in isotropic type-II superconductors in the presence of strong thermal fluctuations by means of 'driven-diffusion' Monte Carlo simulations of a discretized London theory with finite magnetic penetration depth. We calculate the current-voltage (I-V) characteristics for various temperatures, for transverse as well as longitudinal currents I. From these characteristics, we estimate the linear resistivities R_xx=R_yy and R_zz and compare these with equilibrium results for the vortex-lattice structure factor and the helicity moduli. From this comparison a consistent picture arises, in which the melting of the flux-line lattice occurs in two stages for the system size considered. In the first stage of the melting, at a temperature T_m, the structure factor drops to zero and R_xx becomes finite. For a higher temperature T_z, the second stage takes place, in which the longitudinal superconducting coherence is lost, and R_zz becomes finite as well. We compare our results with related recent numerical work and experiments on cuprate superconductors.Comment: 4 pages, with eps figure

    Optical-phonon resonances with saddle-point excitons in twisted-bilayer graphene

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    Twisted-bilayer graphene (tBLG) exhibits van Hove singularities in the density of states that can be tuned by changing the twisting angle θ\theta. A θ\theta-defined tBLG has been produced and characterized with optical reflectivity and resonance Raman scattering. The θ\theta-engineered optical response is shown to be consistent with persistent saddle-point excitons. Separate resonances with Stokes and anti-Stokes Raman scattering components can be achieved due to the sharpness of the two-dimensional saddle-point excitons, similar to what has been previously observed for one-dimensional carbon nanotubes. The excitation power dependence for the Stokes and anti-Stokes emissions indicate that the two processes are correlated and that they share the same phonon.Comment: 5 pages, 6 figure

    Ceftolozane/tazobactam for the treatment of serious Pseudomonas aeruginosa infections: a multicentre nationwide clinical experience

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    This study describes the largest clinical experience using ceftolozane/tazobactam (C/T) for different Pseudomonas aeruginosa infections. A retrospective study was performed at 22 hospitals in Italy (June 2016\u2013March 2018). All adult patients treated with 654 days of C/T were enrolled. Successful clinical outcome was defined as complete resolution of clinical signs/symptoms related to P. aeruginosa infection and lack of microbiological evidence of infection. C/T treatment was documented in 101 patients with diverse infections, including nosocomial pneumonia (31.7%), acute bacterial skin and skin-structure infection (20.8%), complicated UTI (13.9%), complicated IAI (12.9%), bone infection (8.9%) and primary bacteraemia (5.9%). Over one-half of P. aeruginosa strains were XDR (50.5%), with 78.2% of isolates resistant to at least one carbapenem. C/T was used as first-line therapy in 39 patients (38.6%). When used as second-line or later, the most common reasons for discontinuation of previous antibiotics were in vitro resistance of P. aeruginosa and clinical failure of previous therapy. Concomitant antibiotics were reported in 35.6% of patients. C/T doses were 1.5 g q8h in 70 patients (69.3%) and 3 g q8h in 31 patients (30.7%); median duration of C/T therapy was 14 days. Overall clinical success was 83.2%. Significant lower success rates were observed in patients with sepsis or receiving continuous renal replacement therapy (CRRT). Mild adverse events were reported in only three patients. C/T demonstrated a favourable safety and tolerability profile regardless of the infection type. Clinicians should be aware of the risk of clinical failure with C/T therapy in septic patients receiving CRRT

    Dynamic correlations in an ordered c(2Ă—\times2) lattice gas

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    We obtain the dynamic correlation function of two-dimensional lattice gas with nearest-neighbor repulsion in ordered c(2Ă—\times2) phase (antiferromagnetic ordering) under the condition of low concentration of structural defects. It is shown that displacements of defects of the ordered state are responsible for the particle number fluctuations in the probe area. The corresponding set of kinetic equations is derived and solved in linear approximation on the defect concentration. Three types of strongly correlated complex jumps are considered and their contribution to fluctuations is analysed. These are jumps of excess particles, vacancies and flip-flop jumps. The kinetic approach is more general than the one based on diffusion-like equations used in our previous papers. Thus, it becomes possible to adequately describe correlations of fluctuations at small times, where our previous theory fails to give correct results. Our new analytical results for fluctuations of particle number in the probe area agree well with those obtained by Monte Carlo simulations.Comment: 10 pages, 7 figure

    In-hospital and out-of-hospital stroke in patients with COVID-19: two different diseases?

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    Background: Ischemic stroke is a known complication of COVID-19. It may have a different pathogenesis and worse outcome compared to stroke&nbsp;in patients without COVID-19. Furthermore, patients with COVID-19 and out-of-hospital stroke&nbsp;onset might have different characteristics compared to patients with COVID-19 and in-hospital stroke onset. The aim of our study was to analyze the characteristics of patients with stroke with and without COVID-19 and of patients&nbsp;with COVID-19 with in-hospital and out-of-hospital stroke. Methods: We performed a retrospective study of all consecutive patients admitted to our hospital with ischemic stroke between October 2020 and February 2021. We compared functional outcome, lab test, demographic, and clinical characteristics between patients with or without COVID-19. We performed a sub-analysis comparing patients with COVID-19 and in-hospital and out-of-hospital stroke onset. Results: We included in the final analysis 137 patients of whom 26 with COVID-19. Half (13) had out-of-hospital stroke and half in-hospital stroke onset. Overall, patients with COVID-19 had higher mortality compared to the control group (27% vs 9%, p: 0.02), and non-significantly lower rate of good functional outcome (50% vs 63%, p: 0.22). Patients with COVID-19 and out-of-hospital stroke had higher rate of good functional outcome (69% vs 39%, p: 0.05), higher lymphocyte count, and lower D-dimer compared with patients with in-hospital stroke onset. Conclusions: Patients with stroke and COVID-19 had higher mortality compared to patients without COVID-19. Among patients with COVID-19 those with out-of-hospital stroke had better outcome and fewer blood test abnormalities compared to patients with in-hospital stroke

    CT Guided fine needle aspiration biopsy of pulmonary lesions under 15 mm of diameter: results on 68 consecutive patients

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    BACKGROUND Most reports on lung fine needle aspiration cytology (FNAC) demonstrate that the diagnostic accuracy tends to decrease with the size of the lesions, and that the frequency of complications increases as the size of lesions decreases. PURPOSE The aim of this prospective study was to describe the accuracy and incidence of complications related to FNAC of solitary pulmonary nodules (SPNs) of 15 mm or less in diameter. Moreover, we evaluated how this procedure during the initial evaluation of patients with SPN can reduce the number of unnecessary surgery. MATERIAL AND METHODS From January 2012 to December 2014, 225 patients with an SPN between 7-15 mm in diameter were referred to our Institution. Patients with risk factors such as ASA 3, FEV1
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