Microscopic Model of Charge Carrier Transfer in Complex Media

We present a microscopic model of a charge carrier transfer under an action of a constant electric field in a complex medium. Generalizing previous theoretical approaches, we model the dynamical environment hindering the carrier motion by dynamic percolation, i.e., as a medium comprising particles which move randomly on a simple cubic lattice, constrained by hard-core exclusion, and may spontaneously annihilate and re-appear at some prescribed rates. We determine analytically the density profiles of the "environment" particles, as seen from the stationary moving charge carrier, and calculate its terminal velocity as the function of the applied field and other system parameters. We realize that for sufficiently small external fields the force exerted on the carrier by the "environment" particles shows a viscous-like behavior and define an analog of the Stokes formula for such dynamic percolative environments. The corresponding friction coefficient is also derived.Comment: appearing in Chem. Phys. Special Issue on Molecular Charge Transfer in Condensed Media - from Physics and Chemistry to Biology and Nano-Engineering, edited by A.Kornyshev (Imperial College London), M.Newton (Brookhaven Natl Lab) and J.Ulstrup (Technical University of Denmark

High efficacy and low toxicity of weekly docetaxel given as first-line treatment for metastatic breast cancer

Background: Docetaxel is one of the most effective antitumor agents currently available for the treatment of metastatic breast cancer (MBC). This phase II multicenter study prospectively analyzed the efficacy and toxicity of docetaxel given on a weekly schedule as first-line treatment of metastatic breast cancer. Patients and Methods: All patients received docetaxel, 35 mg/m(2) weekly for 6 weeks, followed by 2 weeks of rest. Subsequent cycles ( 3 weeks of treatment, 2 weeks of rest) were given until a maximum of 5 cycles or disease progression. Premedication consisted of 8 mg dexamethasone intravenously 30 min prior to the infusion of docetaxel. Results: Fifty-four patients at a median age of 58 years with previously untreated MBC were included in the study. A median of 10 doses ( median cumulative dose 339 mg/m(2)) was administered ( range: 2 - 18). The overall response rate was 48.1% ( 95% CI: 34 - 61%, intent-to-treat). Median survival was 15.8 months and median time to progression was 5.9 months ( intent-to-treat). Hematological toxicity was mild with absence of neutropenia-related complications. Grade 3 neutropenia was observed in 3.7% of patients and grade 3 and 4 anemia was observed in 5.6 and 1.9% of patients, respectively. Conclusion: The weekly administration of docetaxel is highly efficient and safe as first-line treatment for MBC and may serve as an important treatment option specifically in elderly patients and patients with a reduced performance status. Copyright (C) 2005 S. Karger AG, Basel

Generalized model for dynamic percolation

We study the dynamics of a carrier, which performs a biased motion under the influence of an external field E, in an environment which is modeled by dynamic percolation and created by hard-core particles. The particles move randomly on a simple cubic lattice, constrained by hard-core exclusion, and they spontaneously annihilate and re-appear at some prescribed rates. Using decoupling of the third-order correlation functions into the product of the pairwise carrier-particle correlations we determine the density profiles of the "environment" particles, as seen from the stationary moving carrier, and calculate its terminal velocity, V_c, as the function of the applied field and other system parameters. We find that for sufficiently small driving forces the force exerted on the carrier by the "environment" particles shows a viscous-like behavior. An analog Stokes formula for such dynamic percolative environments and the corresponding friction coefficient are derived. We show that the density profile of the environment particles is strongly inhomogeneous: In front of the stationary moving carrier the density is higher than the average density, $\rho_s$, and approaches the average value as an exponential function of the distance from the carrier. Past the carrier the local density is lower than $\rho_s$ and the relaxation towards $\rho_s$ may proceed differently depending on whether the particles number is or is not explicitly conserved.Comment: Latex, 32 pages, 4 ps-figures, submitted to PR

International trade and domestic competition: Evidence from Belgium

We investigate the effect of domestic market competition on firm-level export intensity. We employ a comprehensive dataset of Belgian firms from 2005–2008, when the fall in the number of firms engaged in trade was accompanied by a growing amount of transactions. The resulting increase in the domestic concentration of Belgian firms has sparked numerous debates, since the direction of causality between domestic market structure and export performance is unclear. We apply the fractional logit estimator and control for both self-selection and simultaneity bias. We find that a positive linkage exists between the level of competition and export intensity

Hand antisepsis without decreasing efficacy by shortening the rub-in time of alcohol-based handrubs to 15 seconds

BackgroundA previous study among neonatal intensive care unit (NICU) nurses showed that the antibacterial efficacy of alcohol-based handrubs (ABHR) can be achieved in 15 s instead of 30 s with a significant increase in the frequency of hand antisepsis. This study aimed to examine 15-s vs 30-s antisepsis performance by measuring microbial load on fingertips and compliance among nurses in a low-risk gynaecological ward.MethodsAn independent trained observer monitored the frequency and compliance with hand antisepsis during shifts in a crossover design. Fingertips including thumbs were rinsed in soy broth before hand rubbing at the beginning of a shift and then hourly to determine the bacterial load. Performance activity was assigned to the contamination class of the Fulkerson scale. Immediately before the lunch break, volunteers cleaned their hands for a randomly determined application time of 15 or 30 s.ResultsExamination of bacterial load on fingertips revealed no difference between 15 vs 30 s application time. Controlled hand antisepsis before the lunch break also showed no difference in efficacy for either test series. Participants rubbing for 15 s were more likely to perform hand antisepsis compared with those rubbing for 30 s ( P=0.2). The compliance increased from 54.7% to 69.5% in the 15-s trial.DiscussionShortening the duration for hand antisepsis did not decrease efficacy. Shortening the application time to 15 s should be considered within the critical components of a successful multimodal intervention strategy to improve hand-hygiene compliance in clinical practice

High body burdens of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) in California women.

Following our first report on elevated polybrominated diphenyl ether (PBDE) concentrations in California women, we expanded our investigation to include diverse groups of local women. We analyzed additional adipose and serum samples collected in the late 1990s from San Francisco Bay Area women participating in a breast cancer study and in a reproductive study, respectively. Adipose samples (n = 32) were analyzed by low-resolution mass spectrometry in negative-ion chemical ionization mode, whereas serum samples (n = 50) were analyzed by dual-column gas chromatography with electron capture detection. The results confirmed our earlier findings. Concentrations of 2,2,4,4 -tetrabromodiphenyl ether (BDE-47) in contemporary California women ranged between 5 and 510 ng/g lipid, with a median (16.5 ng/g lipid) 3-10 times higher than those reported from Europe. In contrast, PBDEs were not measurable in any of 420 archived serum samples collected in the 1960s from San Francisco Bay Area women participating in a study of child development. BDE-47 concentrations did not increase with age or with concentrations of a polychlorinated biphenyl (PCB-153), suggesting other routes of exposure in addition to diet. Rising body burdens of endocrine-disrupting chemicals such as PBDEs may pose a potential public health threat

Role of information and communication networks in malaria survival

<p>Abstract</p> <p>Background</p> <p>Quite often symptoms of malaria go unrecognized or untreated. According to the Multilateral Initiative on Malaria, 70% of the malaria cases that are treated at home are mismanaged. Up to 82% of all malaria episodes in sub-Saharan Africa are treated outside the formal health sector. Fast and appropriate diagnosis and treatment of malaria is extremely important in reducing morbidity and mortality.</p> <p>Method</p> <p>Data from 70 different countries is pooled together to construct a panel dataset of health and socio-economic variables for a time span of (1960–2004). The generalized two-stage least squares and panel data models are used to investigate the impact of information and communication network (ICN) variables on malaria death probability. The intensity of ICN is represented by the number of telephone main lines per 1,000 people and the number of television sets per 1,000 people.</p> <p>Results</p> <p>The major finding is that the intensity of ICN is associated with reduced probability of deaths of people that are clinically identified as malaria infected. The results are robust for both indicators i.e. interpersonal and mass communication networks and for all model specifications examined.</p> <p>Conclusion</p> <p>The results suggest that information and communication networks can substantially scale up the effectiveness of the existing resources for malaria prevention. Resources spent in preventing malaria are far less than needed. Expanded information and communication networks will widen the avenues for community based "participatory development", that encourages the use of local information, knowledge and decision making. Timely information, immediate care and collective knowledge based treatment can be extremely important in reducing child mortality and achieving the millennium development goal.</p