Non-sinusoidal current and current reversals in a gating ratchet

In this work, the ratchet dynamics of Brownian particles driven by an external sinusoidal (harmonic) force is investigated. The gating ratchet effect is observed when another harmonic is used to modulate the spatially symmetric potential in which the particles move. For small amplitudes of the harmonics, it is shown that the current (average velocity) of particles exhibits a sinusoidal shape as a function of a precise combination of the phases of both harmonics. By increasing the amplitudes of the harmonics beyond the small-limit regime, departures from the sinusoidal behavior are observed and current reversals can also be induced. These current reversals persist even for the overdamped dynamics of the particles.Comment: 11 pages, 9 figure

Performance evaluation of IB-DFE-based strategies for SC-FDMA systems

The aim of this paper is to propose and evaluate multi-user iterative block decision feedback equalization (IB-DFE) schemes for the uplink of single-carrier frequency-division multiple access (SC-FDMA)-based systems. It is assumed that a set of single antenna users share the same physical channel to transmit its own information to the base station, which is equipped with an antenna array. Two space-frequency multi-user IB-DFE-based processing are considered: iterative successive interference cancellation and parallel interference cancellation. In the first approach, the equalizer vectors are computed by minimizing the mean square error (MSE) of each individual user, at each subcarrier. In the second one, the equalizer matrices are obtained by minimizing the overall MSE of all users at each subcarrier. For both cases, we propose a simple yet accurate analytical approach for obtaining the performance of the discussed receivers. The proposed schemes allow an efficient user separation, with a performance close to the one given by the matched filter bound for severely time-dispersive channels, with only a few iterations

Closed-loop control strategy with improved current for a flashing ratchet

We show how to switch on and off the ratchet potential of a collective Brownian motor, depending only on the position of the particles, in order to attain a current higher than or at least equal to that induced by any periodic flashing. Maximization of instant velocity turns out to be the optimal protocol for one particle but is nevertheless defeated by a periodic switching when a sufficiently large ensemble of particles is considered. The protocol presented in this article, although not the optimal one, yields approximately the same current as the optimal protocol for one particle and as the optimal periodic switching for an infinite number of them.Comment: 4 pages, 4 figure

Dormancy within Staphylococcus epidermidis biofilms: an immunoproteomic characterization

Dormant bacteria within biofilms contribute to biofilm heterogeneity. Consequently, physiological heterogeneity of biofilms may influence host immune response and tolerance to antibiotics. Recently, we described an in vitro model to modulate dormancy in S. epidermidis biofilms. Here, we present a study based on immunoproteomics, where we compared the reactive profile of S. epidermidis biofilm proteins with prevented and induced dormancy, to human sera. A total of 19 immunoreactive proteins were identified by MALDI-TOF/TOF. Most of these proteins present molecular functions, such as catalytic activity and ion binding. CodY and GpmA proteins were more reactive to sera when biofilm dormancy was induced, while FtnA and ClpP were more reactive when dormancy was prevented. This is the first work identifying protein immunoreactivity differences between bacterial biofilms with induced or prevented dormancy. Considering the importance of dormancy within biofilms, further studies on these proteins may provide insights into the mechanisms related to dormancy and help improving current understanding on how dormancy affects the host immune response

Subcutaneous Fat Necrosis Following Induced Hypothermia

A necrose gorda do tecido celular subcutâneo do recém-nascido está associada a asfixia neonatal, aspiração de mecónio, convulsões ou hipotermia. A hipercalcemia é a complicação mais frequente, podendo em alguns casos ser grave e exigir terapêutica específica. Relata-se o caso de um recém-nascido de cesariana emergente por sofrimento fetal, tendo sido submetido a protocolo de hipotermia induzida. Foi diagnosticado com necrose gorda do recém-nascido ao 11º dia de internamento. No 23º dia identificou-se hipercalcemia, tendo iniciado terapêutica com pamidronato, com consequente diminuição gradual da calcemia. Sublinha-se a necessidade da identificação rápida de necrose gorda, possibilitando antecipar a hipercalcemia e iniciar terapêutica precoce

Antiplatelet agents and/or anticoagulants are not associated with worse outcome following nonvariceal upper gastrointestinal bleeding

BACKGROUND: Nonvariceal upper gastrointestinal bleeding emerges as a major complication of using antiplatelet agents and/or anticoagulants and represents a clinical challenge in patients undergoing these therapies. AIM: To characterize patients with nonvariceal upper gastrointestinal bleeding related to antithrombotics and their management, and to determine clinical predictors of adverse outcomes. METHODS: Retrospective cohort of adults who underwent upper gastrointestinal endoscopy after nonvariceal upper gastrointestinal bleeding from 2010 to 2012. The outcomes were compared between patients exposed and not exposed to antithrombotics. RESULTS: Five hundred and forty-eight patients with nonvariceal upper gastrointestinal bleeding (67% men; mean age 66.5 ± 16.4 years) were included, of which 43% received antithrombotics. Most patients had comorbidities. Peptic ulcer was the main diagnosis and endoscopic therapy was performed in 46% of cases. The 30-day mortality rate was 7.7% (n = 42), and 36% were bleeding-related. The recurrence rate was 9% and 14% of patients with initial endoscopic treatment needed endoscopic retreatment. There were no significant differences between the exposed and non-exposed groups in most outcomes. Co-morbidities, hemodynamic instability, high Rockall score, low hemoglobin (7.76 ± 2.72 g/dL) and higher international normalized ratio (1.63 ± 1.13) were associated significantly with mortality in a univariate analysis. CONCLUSIONS: Adverse outcomes were not associated with antithrombotic use. The management of nonvariceal upper gastrointestinal bleeding constitutes a challenge to clinical performance optimization and clinical cooperation.info:eu-repo/semantics/publishedVersio