49 research outputs found
Poisson-Poincar\'e reduction for Field Theories
Given a Hamiltonian system on a fiber bundle, there is a Poisson covariant
formulation of the Hamilton equations. When a Lie group G acts freely,
properly, preserving the fibers of the bundle and the Hamiltonian density is
G-invariant, we study the reduction of this formulation to obtain an analogue
of Poisson-Poincar\'e reduction for field theories. This procedure is related
to the Lagrange-Poincar\'e reduction for field theories via a Legendre
transformation. Finally, an application to a model of a charged strand evolving
in an electric field is given.Comment: 34 page
Nous tipus de biodièsel
En aquest article es vol exposar l'estat actual de les tecnologies disponibles per a la producció de biocombustibles aplicables a motors dièsel, amb una especial atenció a les possibilitats d'aplicació de les lipases lliures o immobilitzades per a l'obtenció de nous tipus de biocombustibles que s'estan regulant legalment per tal d'incentivar la substitució gradual del petroli com a font única de combustibles per a l'automoció.This article aims to explain the current state of available technologies for the production of biofuels applicable in diesel engines,
with special emphasis on the possibilities of implementing the free or immobilized lipases, for the development of new types of biofuels, which are being the subject of legal regulation in order to encourage the gradual replacement of oil as the sole source of fuel for automobiles
Reactions induced by 9Be in a four-body continuum-discretized coupled-channels framework
We investigate the elastic scattering of 9Be on 208Pb at beam energies above (50MeV) and below (40MeV) the Coulomb barrier. The reaction is described within a four-body framework using the Continuum-Discretized Coupled-Channels (CDCC) method. The 9Be projectile states are generated using the analytical Transformed Harmonic Oscillator (THO) basis in hyperspherical coordinates. Our calculations confirm the importance of continuum effects at low energies.Ministerio de Economía y Competitividad FIS2014-53448-c2-1-P FIS2014-51941-PJunta de Andalucía FQM-160 P11-FQM-763
Three-body nuclei and their astrophysical implications: The case of 6He
The analytic THO method [1] is generalized to study three-body nuclei of astrophysical interest, and applied to 6He. Results are consistent with previous publications and experimental data [2, 3].Economía y Competitividad FPA2009-07653 FIS2011-28738-c02-01Junta de Andalucía FQM-7632Consolider-Ingenio 2010 Programme CPAN CSD2007-0004
Astrophysical reaction rate for 9 Be formation within a three-body approach
The structure of the Borromean nucleus 9Be (α+α+n) is addressed within a three-body approach using the analytical transformed harmonic oscillator method. The three-body formalism provides an accurate description of the radiative capture reaction rate for the entire temperature range relevant in astrophysics. At high temperatures, results match the calculations based on two-step sequential processes. At low temperatures, where the particles have no access to intermediate two-body resonances, the three-body direct capture leads to reaction rates larger than the sequential processes. These results support the reliability of the method for systems with several charged particles.Ministerio de Economía y Competitividad (España) FPA2009-07653 FIS2011-28738-c02-0Junta de Andalucía FQM-160 P11-FQM-7632Programa Consolider-Ingenio 2010 CSD2007-0004
Marches Agricoles: 1973-1978, Juli/1790 = Agricultural Markets: 197301978 July/1979.
12th International Conference on Nucleus-Nucleus Collisions 2015The scattering of 9Be on 208Pb is addressed within a four-body Continuum-Discretized Coupled-Channels (CDCC) framework, considering a three-body α + α + n projectile plus a structureless target. The projectile states are generated using the analytical Transformed Harmonic Oscillator (THO) basis in hyperspherical coordinates. Both the elastic and breakup channels are described on the same footing. We find a good agreement between our calculations and the experimental data at beam energies around and below the Coulomb barrierMinisterio de Economía y Competitividad FIS2014-53448-c2-1-PMinisterio de Economía y Competitividad FIS2014-51941-PJunta de Andalucía FQM-160Junta de Andalucía P11-FQM- 763
Administration of taurolidine-citrate lock solution for prevention of central venous catheter infection in adult neutropenic haematological patients: a randomised, double-blinded, placebo-controlled trial (TAURCAT)
Background: Catheter-related bloodstream infection (CRBSI) is one of the most frequent complications in patients with cancer who have central venous catheters (CVCs) implanted and is associated with substantial morbidity and mortality. Taurolidine is a non-antibiotic agent with broad-spectrum antimicrobial activity, which has been used as a lock solution to prevent CRBSI in some settings. However, little is known about its usefulness in high-risk adult neutropenic patients with cancer. This prospective randomised clinical trial aims to test the hypothesis that taurolidine-citrate lock solution is more effective than placebo for preventing catheter infection in neutropenic haematological patients.Methods: This study is a prospective, multicentre, randomised, double-blinded, parallel, superiority, placebo-controlled trial. Patients with haematological cancer who are expected to develop prolonged neutropenia (>7 days) and who have a non-tunnelled CVC implanted will be randomised to receive prophylactic taurolidine-citrate-heparin solution using a lock technique (study group) or heparin alone (placebo group). The primary endpoint will be bacterial colonisation of the CVC hubs. The secondary endpoints will be the incidence of CRBSI, CVC removal, adverse events, and 30-day case-fatality rate.Discussion: The lock technique is a preventive strategy that inhibits bacterial colonisation in the catheter hubs, which is the initial step of endoluminal catheter colonisation and the development of infection. Taurolidine is a nontoxic agent that does not develop antibiotic resistance because it acts as an antiseptic rather than an antibiotic. Taurolidine has shown controversial results in the few trials conducted in cancer patients. These studies have important limitations due to the lack of data on adult and/or high-risk neutropenic patients, the type of catheters studied (tunnelled or ports), and the lack of information regarding the intervention (e.g. dwelling of the solution, time, and periodicity of the lock technique). If our hypothesis is proven, the study could provide important solid evidence on the potential usefulness of this preventive procedure in a population at high risk of CRBSI, in whom this complication may significantly impair patient outcome
Antimicrobial use and aetiology of bloodstream infections in critically ill patients during early stages of SARS-CoV-2 pandemic
Background: During early stages of COVID-19 pandemic, antimicrobials were commonly prescribed.Aim: To describe clinical, microbiological and antimicrobial use changes in bloodstream infections (BSI) of ICU patients during the first wave of COVID-19 pandemic compared to pre-COVID-19 era. Methods: Observational cohort study of patients admitted to ICU of Bellvitge University Hospital was conducted during the COVID-19 pandemic (March-June 2020) and before COVID-19 pandemic (March-June 2019). Differences in clinical characteristics, anti-microbial consumption and incidence and aetiology of BSI were measured.Findings: COVID-19 patients had significantly less comorbidities with obesity the only risk factor that increased in frequency. COVID-19 patients more frequently required invasive supportive care measures, had longer median ICU stay and higher mortality rates. The incidence of BSIs was higher in COVID-19 period (RR 3.2 [95%CI 2.2-4.7]), occurred in patients who showed prolonged median ICU stay (21days) and was associated with high mortality rate (47%). The highest increases in the aetiological agents were observed for AmpC-producing bacteria (RR 11.1 [95%CI 2.6-47.9]) and non-fermenting rods (RR 7.0 [95% CI 1.5-31.4]). The emergence of bacteraemia caused by Gram-negative rods resistant to amoxicillin-clavulanate, which was used as empirical therapy during early stages of the pandemic, led to an escalation towards broader-spectrum antimicrobials such as mer-openem and colistin which was also associated with the emergence of resistant isolates.Conclusions: The epidemiological shift towards resistant phenotypes in critically ill COVID-19 patients was associated with the selective use of antimicrobials. Our study provides evidence of the impact of empirical therapy on the selection of bacteria and their consequences on BSI over the subsequent months.& COPY; 2022 The Authors. Published by Elsevier Ltd on behalf of The Healthcare Infection Society.This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)