Jose Argelis Martinez - Academia.edu (original) (raw)

Papers by Jose Argelis Martinez

Enferm Infec Microbiol Clin, 2005

1999 IEEE LEOS Annual Meeting Conference Proceedings. LEOS'99. 12th Annual Meeting. IEEE Lasers and Electro-Optics Society 1999 Annual Meeting (Cat. No.99CH37009)

Chatoyant is a software tool developed to meet the nee& of mixed technology optoelectronic system... more Chatoyant is a software tool developed to meet the nee& of mixed technology optoelectronic systems designers. We introduce component models and analysis techniques that enable our tool to support fi.ee-space optoelectronic interconnect system design.

BMC Infectious Diseases, 2015

Background: Predictive models to identify unknown methicillin-resistant Staphylococcus aureus (MR... more Background: Predictive models to identify unknown methicillin-resistant Staphylococcus aureus (MRSA) carriage on admission may optimise targeted MRSA screening and efficient use of resources. However, common approaches to model selection can result in overconfident estimates and poor predictive performance. We aimed to compare the performance of various models to predict previously unknown MRSA carriage on admission to surgical wards. Methods: The study analysed data collected during a prospective cohort study which enrolled consecutive adult patients admitted to 13 surgical wards in 4 European hospitals. The participating hospitals were located in Athens (Greece), Barcelona (Spain), Cremona (Italy) and Paris (France). Universal admission MRSA screening was performed in the surgical wards. Data regarding demographic characteristics and potential risk factors for MRSA carriage were prospectively collected during the study period. Four logistic regression models were used to predict probabilities of unknown MRSA carriage using risk factor data: "Stepwise" (variables selected by backward elimination); "Best BMA" (model with highest posterior probability using Bayesian model averaging which accounts for uncertainty in model choice); "BMA" (average of all models selected with BMA); and "Simple" (model including variables selected >50% of the time by both Stepwise and BMA approaches applied to repeated random sub-samples of 50% of the data). To assess model performance, cross-validation against data not used for model fitting was conducted and net reclassification improvement (NRI) was calculated. Results: Of 2,901 patients enrolled, 111 (3.8%) were newly identified MRSA carriers. Recent hospitalisation and presence of a wound/ulcer were significantly associated with MRSA carriage in all models. While all models demonstrated limited predictive ability (mean c-statistics <0.7) the Simple model consistently detected more MRSA-positive individuals despite screening fewer patients than the Stepwise model. Moreover, the Simple model improved reclassification of patients into appropriate risk strata compared with the Stepwise model (NRI 6.6%, P = .07). Conclusions: Though commonly used, models developed using stepwise variable selection can have relatively poor predictive value. When developing MRSA risk indices, simpler models, which account for uncertainty in model selection, may better stratify patients' risk of unknown MRSA carriage.

Proceedings of the 36th ACM/IEEE conference on Design automation conference - DAC '99, 1999

Chatoyant models free-space opto-electronic components and systems and performs simulations and a... more Chatoyant models free-space opto-electronic components and systems and performs simulations and analyses that allow designers to make informed system level trade-offs. Recently, the use of MEM bulk and surface micro-machining technology has enabled the fabrication of micro-optical-mechanical systems. This paper presents our models for diffractive optics and new analysis techniques which extend Chatoyant to support optical MEMS design. We show these features in the simulation of two optical MEM systems.

Optics in Computing, 2001

Micro-optical-electrical-mechanical systems (MOEMS) present a new set of challenges for mixed tec... more Micro-optical-electrical-mechanical systems (MOEMS) present a new set of challenges for mixed technology systems on a chip (SoC) designers including the need for mixed-signal multi-domain simulation. We present new modeling techniques for optical and mechanical MEM components and apply these models for improved system-level simulation accuracy of MOEMS switches.

Marine Pollution Bulletin, 2006

We have monitored the distribution, population status, breeding success, turnover rate and diet o... more We have monitored the distribution, population status, breeding success, turnover rate and diet of a Peregrine Falcon population in Bizkaia (North of Spain) since 1997. On the 13th November 2002, the tanker Prestige sunk off La Coruñ a (NW Spain) causing an oil spill that affected the whole of the Cantabrian Coast and the Southwest of France. The total number of birds affected by the Prestige oil spill was expected to be between 115,000 and 230,000, some of them raptors. The loss of clutches during the incubation period increased significantly and was correlated with the loss of females. Moreover, the turnover rate of the population increased from 21% to 30%. The polycyclic aromatic hydrocarbon concentrations in the eggs, collected from five nests after they were deserted, ranged from 21.20 ng/g to 461.08 ng/g, values which are high enough to cause the death of the embryos and poisoning of adult birds. The effects of pollution reached inland since some inland-breeding falcons prey on shorebirds that use rivers during their migratory flights. As the Prestige oil spill has clearly resulted in increased rates of adult mortality and reduced fertility, we suggest that the environmental authorities urgently undertake measures aimed at protecting the Peregrine Falcon in Bizkaia.

Journal of Hospital Infection, 2009

The aim of this study was to assess the role of add-on devices for the prevention of phlebitis an... more The aim of this study was to assess the role of add-on devices for the prevention of phlebitis and other complications associated with the use of peripheral catheters. Patients admitted to an infectious diseases ward and requiring the insertion of a peripheral catheter for at least 24 h were randomly allocated to be managed with or without add-on devices. Incidence of phlebitis and all complications were the primary outcomes. Extravasation, inadvertent withdrawal, obstruction and rupture were considered to be mechanical complications, and analysis was performed using survival methods. Of 683 evaluated catheters, 351 were allocated to the add-on device arm and 332 to the control arm. Despite randomisation, patients in the add-on device group were older (P ¼ 0.048), less likely to have human immunodeficiency virus (P ¼ 0.02) and more likely to have received antibiotics (P ¼ 0.05). After adjustment for these variables, the hazard ratio for phlebitis remained non-significant (hazard ratio: 0.95; 95% confidence interval: 0.7e1.3), but the risk of mechanical complications became lower in the add-on device arm (0.68; 0.5e0.94). This translated into a trend towards a lower risk of any complication (0.83; 0.67e1.01). The beneficial effect on mechanical or all

Journal of Clinical Microbiology, 2006

In patients with Escherichia coli bacteremia, data on the relationship of phylogenetic background... more In patients with Escherichia coli bacteremia, data on the relationship of phylogenetic background, biofilm production, and degree of bacteremia with clinical variables and prognosis are scarce. During a 1-year period, all adults with bacteremia due to Escherichia coli diagnosed at a university center were enrolled. Determination of phylogenetic background, biofilm production, and genotyping was performed with all strains, and the time to positivity of blood culture vials was recorded. A total of 185 episodes of diverse-source E. coli bacteremia was analyzed. Strains of phylogroup D were predominant (52%). Phylogroup A isolates were associated with pneumonia and prior antibiotic intake, B1 with an abdominal source of infection, B2 with the absence of urological abnormalities, and D with urological abnormalities and age below 65 years. Resistance to antibiotics and no biofilm production were concentrated in phylogroup A strains. Biofilm production was not associated with any clinical ...

Journal of Antimicrobial Chemotherapy, 2006

Background: The increasing prevalence of extended-spectrum b-lactamase (ESBL)-producing Enterobac... more Background: The increasing prevalence of extended-spectrum b-lactamase (ESBL)-producing Enterobacteriaceae will probably trigger a rise in the use of carbapenems. The effect of these antibiotics on the risk of involvement of ESBL-producing organisms in serious infections is unclear. Methods: Retrospective analysis of 2172 episodes of healthcare-associated bacteraemia diagnosed during a 3 year period in a teaching hospital. Putative risk factors included demographics, co-morbidities, previous isolation of an ESBL-producing organism and exposure to antibiotics. Univariate and multivariate analysis of the association of risk factors with ESBL-producing organisms was performed in the entire series of bacteraemic episodes and in those due to Escherichia coli or Klebsiella spp. Results: In the entire series, prior isolation of an ESBL-producing organism [odds ratio (OR) 5.9 (3.02, 11.5)]; an ultimately/finally fatal co-morbidity [OR 2.8 (1.55, 4.95)]; renal transplantation [OR 4.3 (1.96, 9.63)]; a urinary source [OR 4.2 (2.22, 7.84)]; shock [OR 2.4 (1.35, 4.1)] and previous use of cephalosporins [OR 2.6 (1.54, 4.51)], carbapenems [OR 2.5 (1.24, 5.05)] and glycopeptides [OR 0.4 (0.13, 0.93)] were significantly associated with ESBL-producing E. coli or Klebsiella spp. by multivariate analysis. Prior isolation of an ESBL-producing organism, an ultimately/finally fatal co-morbidity, renal transplantation, and previous use of cephalosporins and carbapenems were also significant in the analysis restricted to episodes due to E. coli or Klebsiella spp. Conclusions: In patients with healthcare-associated bacteraemia, prior use of carbapenems may be only second to cephalosporins as the most significant antibiotic exposure associated with the involvement of ESBL-producing organisms.

Intensive Care Medicine, 2008

Objective: To assess the role of antipseudomonal agents on Pseudomonas aeruginosa colonization an... more Objective: To assess the role of antipseudomonal agents on Pseudomonas aeruginosa colonization and acquisition of resistance. Design: Prospective cohort study. Setting: Two medical intensive care units. Patients and participants: 346 patients admitted for C 48 h. Intervention: Analysis of data from an 8-month study comparing a mixing versus a cycling strategy of antibiotic use. Measurements and results: Surveillance cultures from nares, pharynx, rectum, and respiratory secretions were obtained thrice weekly. Acquisition of resistance was defined as the isolation, after 48 h of ICU stay, of an isolate resistant to a given antibiotic if culture of admission samples were either negative or positive for a susceptible isolate. Emergence of resistance refers to the conversion of a defined pulsotype from susceptible to non-susceptible. Forty-four (13%) patients acquired 52 strains of P. aeruginosa. Administration of piperacillin-tazobactam for C 3 days (OR 2.6, 95% CI 1.09-6.27) and use of amikacin for C 3 days (OR 2.6, 95% CI 1.04-6.7) were positively associated with acquisition of P. aeruginosa, whereas use of quinolones (OR 0.27, 95% CI 0.1-0.7) and antipseudomonal cephalosporins (OR 0.27, 95% CI 0.08-0.9) was protective. Exposure to quinolones and cephalosporins was not associated with the acquisition of resistance, whereas it was linked with usage of all other agents. Neither quinolones nor cephalosporins were a major determinant on the emergence of resistance to themselves, as resistance to these antibiotics developed at a similar frequency in non-exposed patients. Conclusions: In critically ill patients, quinolones and antipseudomonal cephalosporins may prevent the acquisition of P. aeruginosa and may have a negligible influence on the acquisition and emergence of resistance.

IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems, 2003

We present a component-based multi-level mixed-signal design and simulation environment for micro... more We present a component-based multi-level mixed-signal design and simulation environment for microsystems spanning the domains of electronics, mechanics, and optics. The environment provides a solution to the problem of accurate modeling and simulation of multi-domain devices at the system level. This is achieved by partitioning the system into components that are modeled by analytic expressions. These expressions are reduced via linearization into regions of operation for each element of the component and solved with modified nodal analysis in the frequency domain, which guarantees convergence. Feedback among components is managed by a discrete event simulator sending composite signals between components. For electrical, and mechanical components, interaction is via physical connectivity while optical signals are modeled using complex scalar wavefronts, providing the accuracy necessary to model micro-optical components. Simulation speed vs. simulation accuracy can be tuned by controlling the granularity of the regions of operation of the devices, sample density of the optical wavefronts, or the time steps of the discrete event simulator. The methodology is specifically optimized for loosely coupled systems of complex components such as are found in multi-domain microsystems.

Enfermedades Infecciosas y Microbiología Clínica, 2005

presence is universal when the device remains in place for 30 days or longer. Although most of th... more presence is universal when the device remains in place for 30 days or longer. Although most of these episodes of bacteriuria are asymptomatic, up to 30% of them lead to clinical symptoms and complications, including severe sepsis and death. The microorganisms infecting the urine of catheterized patients frequently belong to species less susceptible to antibiotics and form biofilms on both the device's surfaces and probably also on the urothelium. Biofilm formation greatly hampers eradication of the involved flora by antibiotics, probably favors the development of resistance and, in some instances, constitutes the substrate on which crystal precipitates are deposited, eventually resulting in blockage of the catheter lumen. Due to the scarce number of controlled studies, there are still many gaps in our knowledge of important issues concerning the clinical management of patients with indwelling urinary catheters in the community. The present study reviews the epidemiology, risk factors, microbiology, pathogenesis, clinical manifestations, diagnosis, prevention and treatment of catheter-related urinary tract infections in the community setting.

Clinical Microbiology and Infection, 2007

Time-to-positivity is useful in the diagnosis of catheter-related bacteraemia and as a predictor ... more Time-to-positivity is useful in the diagnosis of catheter-related bacteraemia and as a predictor of an endovascular source in patients with Staphylococcus aureus bacteraemia. However, this parameter has been evaluated for only a limited number of microorganisms. In the present study, time-to-positivity was recorded for 1872 episodes of significant monomicrobial bacteraemia diagnosed at a teaching hospital during a 2-year period, and the associated microbial and clinical variables were investigated. According to multivariate analysis, Streptococcus pneumoniae, b-haemolytic streptococci, Escherichia coli, Klebsiella, Enterobacter, Citrobacter and Aeromonas were characterised by fast growth, with an endovascular source, shock, liver cirrhosis and neutropenia also predicting a short time-to-positivity. For patients not receiving appropriate antibiotics, detection of Gram-positive cocci in clusters within 14 h was predictive of Staph. aureus; a time-to-positivity of >21 h ruled out the possibility that a Grampositive organism in chains was a b-haemolytic streptococcus or Strep. pneumoniae, and a time-topositivity of £12 h meant that it was very unlikely that a Gram-negative bacillus was a non-fermenter. A time-to-positivity of £8 h was predictive of a non-urinary tract source in patients with E. coli bacteraemia, and detection of growth within 13 h predicted an endovascular source in those with Staph. aureus bacteraemia. In conclusion, time-to-positivity depended on the microorganism, original source and clinical variables involved. Although this measurement may provide some early clues concerning the microorganisms involved and the source of bacteraemia, its clinical impact remains to be defined.