Modulation of the propagation speed of mechanical waves in silicon quantum dots embedded in a silicon-nitride film

Using a vectorial picosecond self-diffraction method, we evaluate the modification of the speed of the sound in a silicon-nitride film containing silicon quantum dots prepared by remote plasma-enhanced chemical vapor deposition. Our non-contact technique is based on the stimulation of the electrostriction contribution to the nonlinearity of index exhibited by the sample in a multiwave mixing laser experiment. We identified the electronic birefringence using two of the incident beams to generate a self-diffraction signal, then, we modified the third order nonlinear response by means of the optical Kerr effect given by a phase-mismatched third beam which induced electrostriction. Our results indicated that the speed of the sound in a silicon-nitride film can be simultaneously tailored by an electronic nonlinear refractive index, and by an electrostriction effect, both resulting from silicon quantum dots doping.

Spectral clustering of shape and probability prior models for automatic prostate segmentation

Imaging artifacts in Transrectal Ultrasound (TRUS) images and inter-patient variations in prostate shape and size challenge computer-aided automatic or semi-automatic segmentation of the prostate. In this paper, we propose to use multiple mean parametric models derived from principal component analysis (PCA) of shape and posterior probability information to segment the prostate. In contrast to traditional statistical models of shape and intensity priors, we use posterior probability of the prostate region determined from random forest classification to build, initialize and propagate our model. Multiple mean models derived from spectral clustering of combined shape and appearance parameters ensure improvement in segmentation accuracies. The proposed method achieves mean Dice similarity coefficient (DSC) value of 0.96±0.01, with a mean segmentation time of 0.67±0.02 seconds when validated with 46 images from 23 datasets in a leave-one-patient-out validation framework.

[Programs for optimizing the use of antibiotics (PROA) in Spanish hospitals: GEIH-SEIMC, SEFH and SEMPSPH consensus document]

The antimicrobial agents are unique drugs for several reasons. First, their efficacy is higher than other drugs in terms of reduction of morbidity and mortality. Also, antibiotics are the only group of drugs associated with ecological effects, because their administration may contribute to the emergence and spread of microbial resistance. Finally, they are used by almost all medical specialties. Appropriate use of antimicrobials is very complex because of the important advances in the management of infectious diseases and the spread of antibiotic resistance. Thus, the implementation of programs for optimizing the use of antibiotics in hospitals (called PROA in this document) is necessary. This consensus document defines the objectives of the PROA (namely, to improve the clinical results of patients with infections, to minimise the adverse events associated to the use of antimicrobials including the emergence and spread of antibiotic resistance, and to ensure the use of the most cost-efficacious treatments), and provides recommendations for the implementation of these programs in Spanish hospitals. The key aspects of the recommendations are as follows. Multidisciplinary antibiotic teams should be formed, under the auspices of the Infection Committees. The PROA need to be considered as part of institutional programs and the strategic objectives of the hospital. The PROA should include specific objectives based on measurable indicators, and activities aimed at improving the use of antimicrobials, mainly through educational activities and interventions based more on training activities directed to prescribers than just on restrictive measures.

[Who limit vaginal birth for breech presentation: medical practice or Law? Discussion between a medical doctor, a lawyer and the head chief of an university hospital]

The mode of delivery of breech presentation still remains a debate in France. Despite the medical arguments, themselves in debate, exists a legal pressure felt by medical practitioners. Our study highlights the different opinions of medical practitioners, lawyers and medical teachers faced with breech presentation.

Ultrafast optical phase modulation with metallic nanoparticles in ion-implanted bilayer silica

The nonlinear optical response of metallic-nanoparticle-containing composites was studied with picosecond and femtosecond pulses. Two different types of nanocomposites were prepared by an ion-implantation process, one containing Au nanoparticles (NPs) and the other Ag NPs. In order to measure the optical nonlinearities, we used a picosecond self-diffraction experiment and the femtosecond time-resolved optical Kerr gate technique. In both cases, electronic polarization and saturated absorption were identified as the physical mechanisms responsible for the picosecond third-order nonlinear response for a near-resonant 532 nm excitation. In contrast, a purely electronic nonlinearity was detected at 830 nm with non-resonant 80 fs pulses. Regarding the nonlinear optical refractive behavior, the Au nanocomposite presented a self-defocusing effect, while the Ag one presented the opposite, that is, a self-focusing response. But, when evaluating the simultaneous contributions when the samples are tested as a multilayer sample (silica-Au NPs-silica-Ag NPs-silica), we were able to obtain optical phase modulation of ultra-short laser pulses, as a result of a significant optical Kerr effect present in these nanocomposites. This allowed us to implement an ultrafast all-optical phase modulator device by using a combination of two different metallic ion-implanted silica samples. This control of the optical phase is a consequence of the separate excitation of the nonlinear refracting phenomena exhibited by the separate Au and Ag nanocomposites.

Activity of the new cephalosporin CXA-101 (FR264205) against Pseudomonas aeruginosa isolates from chronically-infected cystic fibrosis patients

Chronic respiratory infection caused by Pseudomonas aeruginosa is the main driver of morbidity and mortality in cystic fibrosis (CF) patients. The development of resistance to all available antibiotics is a frequent outcome of these infections. The present study aimed to evaluate the activity of the new cephalosporin CXA-101 (FR264205) against a collection of 100 isolates obtained from 50 CF patients from two Spanish hospitals. The collection included the first (early) and the last (late) available isolate from each patient (average interval 68 ± 39 months). The MIC50 and MIC90 of CXA-101 were 0.5 and 2 mg/L and the geometric mean MIC was 0.7 mg/L; the MICs for 95% of the isolates were ≤8 mg/L (tentative breakpoint). Only meropenem yielded comparable results, although the MIC90 of this antibiotic was significantly higher (8 mg/L). CXA-101 showed conserved activity against a high proportion of isolates resistant to each of the antibiotics tested (ceftazidime, cefepime, piperacillin-tazobactam, imipenem, meropenem, levofloxacin and tobramycin), with MIC50 values of 1-2 mg/L. Moreover, CXA-101 retained good activity against multidrug-resistant strains, with MIC50 and MIC90 values of 2 and 16 mg/L. CXA-101 was also active against late CF isolates (the MIC for 96% was ≤8 mg/L); it was the only antibiotic tested to which a similar percentage of early and late isolates was susceptible. These results show that, despite a slight increase in MICs, major cross-resistance to CXA-101 did not develop during treatment of CF patients with the currently available antipseudomonal agents. Therefore, CXA-101 is envisaged as a valuable alternative for the treatment of chronic respiratory infection caused by P. aeruginosa in CF patients.

Bacterial hypermutation in cystic fibrosis, not only for antibiotic resistance

Hypermutable or mutator microorganisms are those that have an increased spontaneous mutation rate as a result of defects in DNA repair or error avoidance systems. Over the last two decades, several studies have provided strong evidence for a relevant role of mutators in the evolution of natural bacterial populations, particularly in the field of infectious diseases. Among them, chronic respiratory infection with Pseudomonas aeruginosa in cystic fibrosis (CF) patients was the first natural environment to reveal the high prevalence and important role of mutators. A remarkable positive selection of mutators during the course of the chronic infection has been reported, mainly as a result of the emergence of DNA mismatch repair system (mutS, mutL or mutU)-deficient mutants, although strains defective in the GO system (mutM, mutY and mutT) have also been observed. High frequencies of mutators have also been noted among other pathogens in the CF setting, particularly Staphylococcus aureus and Haemophilus influenzae. Enhanced antimicrobial resistance development is the most thoroughly studied consequence of mutators in CF and other chronic infections, although recent studies show that mutators may additionally have important effects on the evolution of virulence, genetic adaptation to the airways of CF patients, persistence of colonization, transmissibility, and perhaps lung function decline. Further prospective clinical studies are nevertheless still needed for an in-depth evaluation of the impact of mutators on disease progression and outcome.

Cohort study to test the predictability of the Melbourne criteria for activation of the medical emergency team

OBJECTIVE

To test the predictability of the Melbourne criteria for activation of the medical emergency team (MET) to identify children at risk of developing critical illness.

DESIGN

Cohort study.

SETTING

Admissions to all paediatric wards at the University Hospital of Wales.

OUTCOME MEASURES

Paediatric high dependency unit admission, paediatric intensive care unit admission and death.

RESULTS

Data were collected on 1000 patients. A single abnormal observation determined by the Melbourne Activation Criteria (MAC) had a sensitivity of 68.3% (95% CI 57.7 to 77.3), specificity 83.2% (95% CI 83.1 to 83.2), positive predictive value (PPV) 3.6% (95% CI 3.0 to 4.0) and negative predictive value 99.7% (95% CI 99.5 to 99.8) for an adverse outcome. Seven of the 16 children (43.8%) would not have transgressed the MAC prior to the adverse outcomes. Four hundred and sixty-nine of the 984 children (47.7%) who did not have an adverse outcome would have transgressed the MAC at least once during the admission.

CONCLUSION

The MAC has a low PPV and its full implementation would result in a large number of false positive triggers. Further research is required to determine the relative contribution of the components of this complex intervention (Paediatric Early Warning System, education and MET) on patient outcome.

The Relationship Between Safety Attitudes and Occupational Accidents

This research provides empirical evidence on the relationships between employee attitudes to safety issues and accident indicators in a Spanish context. The research attempts to review to what degree those attitudes reflect a collective, or shared, climate for safety within a number of organizations. Data were gathered from workers in a number of industries in Valencia (Spain) by questionnaire. A total of 1,234 valid questionnaires were completed and formed the basis for subsequent analysis. Analysis of the attitude dimensions found a similar structure to that found in previous research in other countries, as well as identifying those dimensions shared within groups, more likely to represent safety climate. In terms of explaining accidents, the data showed that variables dealing with the work environment, in particular the presence of Workplace Hazards, and the individual’s approach to working safely were directly related to accident outcomes, explaining 19% of the variability in accident history. These variables were, in turn, related to the assessment of safety climate, suggesting that individual attitude variables act as a mediator between climate and accident occurrence. This paper represents one of the few attempts to explain the influence of safety climate, work environment, and individual attitudes on accident outcomes in the Spanish environment, using a theoretical model developed and validated in another European context.

Inhibition of the two-photon absorption response exhibited by a bilayer TiO2 film with embedded Au nanoparticles

We use two different synthesis approaches for the preparation of TiO(2) films in order to study their resulting third order optical nonlinearity, and its modification by the inclusion of Au nanoparticles in one of the samples. An ultrasonic spray pyrolysis method was used for preparing a TiO(2) film in which we found two-photon absorption as a dominant nonlinear effect for 532 nm and 26 ps pulses; and a purely electronic nonlinearity at 830 nm for 80 fs pulses. A strong optical Kerr effect and the inhibition of the nonlinear optical absorption in 532 nm can be obtained for the first sample if Au nanoparticles embedded in a second TiO(2) film prepared by a sol-gel technique are added to it. We used an optical Kerr gate, z-scan, a multi-wave mixing experiment and an input-output transmittance experiment for measuring the optical nonlinearities.

Composite renal cell carcinoma with clear cell renal cell carcinomatous and carcinoid tumoral elements: a first case report

Renal endocrine tumours are extremely rare, and carcinoid tumoral elements in renal cell carcinoma have never been reported. This is the first report of a composite renal cell carcinoma containing a clear cell renal cell carcinoma associated with carcinoid tumoral elements, in a patient with synchronous metastatic disease. In the absence of specific radiological and clinical manifestations, typical morphological features as well as an immunostaining profile of neuroendocrine differentiation were identified by microscopy. Secondary nodal and liver localisations were characterised by carcinoid elements only. Despite antiangiogenic therapy, liver metastasis progressed, suggesting that adjuvant therapy cannot be based on the presence of the clear cell renal cell carcinoma component. In this context, extensive tissue sampling is recommended to reveal the endocrine component that is the most aggressive element of such a composite carcinoma.

Tissue tropism and promoter sequence variation in caprine arthritis encephalitis virus infected goats

Caprine arthritis encephalitis virus is a lentivirus that infects goats and is closely related to maedi-visna virus of sheep. Infection with CAEV results in multiple discrete disease manifestations in goats which can include chronic arthritis, mastitis, pneumonia or encephalomyelitis. Presently, no satisfactory mechanistic rationale for viral tropism has been put forward. We propose that specific sequences in the lentiviral promoter (U3 region of the viral long terminal repeat) are associated with viral tissue tropism and subsequent disease expression. A total of 41 distinct CAE viral promoter regions were amplified, sequenced and phylogenetically compared from the tissues of 24 CAEV-infected goats demonstrating a variety of disease manifestations. Phylogenetically, we identified no tendency for clustering of these promoter sequences into tissue-specific groups. These results therefore do not provide evidence for the study hypothesis. However, multiple motifs within the U3 promoter region were highly conserved both within the entire collection of sequences and within tissue-specific groups.