Detecting Suspected Pump Thrombosis in Left Ventricular Assist Devices via Acoustic Analysis.

OBJECTIVE: Left ventricular assist devices (LVADs) fail in up to 10% of patients due to the development of pump thrombosis. Remote monitoring of patients with LVADs can enable early detection and, subsequently, treatment and prevention of pump thrombosis. We assessed whether acoustical signals measured on the chest of patients with LVADs, combined with machine learning algorithms, can be used for detecting pump thrombosis. METHODS: 13 centrifugal pump (HVAD) recipients were enrolled in the study. When hospitalized for suspected pump thrombosis, clinical data and acoustical recordings were obtained at admission, prior to and after administration of thrombolytic therapy, and every 24 hours until laboratory and pump parameters normalized. First, we selected the most important features among our feature set using LDH-based correlation analysis. Then using these features, we trained a logistic regression model and determined our decision threshold to differentiate between thrombosis and non-thrombosis episodes. RESULTS: Accuracy, sensitivity and precision were calculated to be 88.9%, 90.9% and 83.3%, respectively. When tested on the post-thrombolysis data, our algorithm suggested possible pump abnormalities that were not identified by the reference pump power or biomarker abnormalities. SIGNIFICANCE: We showed that the acoustical signatures of LVADs can be an index of mechanical deterioration and, when combined with machine learning algorithms, provide clinical decision support regarding the presence of pump thrombosis.

Avian predators as a biological control system of common vole (Microtus arvalis) populations in north-western Spain: experimental set-up and preliminary results.

BACKGROUND: Ecologically based rodent pest management using biological control has never been evaluated for vole plagues in Europe, although it has been successfully tested in other systems. The authors report on the first large-scale replicated experiment to study the usefulness of nest-box installation for increasing the breeding density of common kestrels (Falco tinnunculus) and barn owls (Tyto alba) as a potential biological control of common vole (Microtus arvalis) abundance in agricultural habitats in north-western Spain. RESULTS: The results show that: (1) population density of both predator species increased in response to both nest-site availability and vole density; (2) voles are a major prey for the common kestrels during the breeding period; (3) vole density during the increase phase of a population cycle may be reduced in crop fields near nest boxes. CONCLUSION: The installation of nest boxes provides nesting sites for barn owls and kestrels. Kestrel populations increased faster than in areas without artificial nests, and the common vole was one of their main prey during the breeding season. The results suggest that local (field) effects could be found in terms of reduced vole density. If so, this could be an environmentally friendly and cheap vole control technique to be considered on a larger scale.

Organic dyes incorporating oligothienylenevinylene for efficient dye-sensitized solar cells.

Two new organic dyes incorporating triphenylamine as a donor and oligothienylenevinylene as a bridge have been synthesized. The new dyes cover the entire visible region and have a power conversion of up to 6.25%.

Triplication of the photocurrent in dye solar cells by increasing the elongation of the π-conjugation in Zn-porphyrin sensitizers.

Porphyrins are promising sensitizers for dye solar cells (DSCs) but narrow absorption bands at 400-450 and 500-650 nm limit their light-harvesting properties. Increasing elongation of the π-conjugation and loss of symmetry causes broadening and a red-shift of the absorption bands, which considerably improves the performance of the DSC. Herein we use an oligothienylenevinylene to bridge a Zn-porphyrin system and the anchoring group of the sensitizer. We separately study the performance of the two basic units: oligothienylenevinylene and Zn-porphyrin. The combined system provides a three-fold enhancement of the photocurrent with respect to parent dyes. This is caused by an additional strong absorption in the region 400-650 nm that leads to flat IPCE of 60%. Theoretical calculations support that the addition of the oligothienylenevinylene unit as a linking bridge creates a charge transfer band that transforms a Zn-porphyrin dye into a push-pull type system with highly efficient charge injection properties.

Electron transfer dynamics in dye-sensitized solar cells utilizing oligothienylvinylene derivates as organic sensitizers.

Two new organic dyes have been synthesized and used as efficient light-harvesting materials in molecular photovoltaic devices. These dyes are based on conjugated thienylvinylene units, with FL-4 consisting of a four-unit thienylvinylene oligomer and its homologue FL-7 which additionally incorporates the electron-donating triphenylamine unit (TPA) into its structure. Upon light excitation both dyes show efficient electron injection into the TiO2 conduction band and slow back electron transfer to the oxidized dye. In fact, for FL-7, the back electron transfer dynamics are slower owing to efficient hole transfer to the TPA moiety situated further from the semiconductor surface. However, the electron recombination kinetics with the oxidized electrolyte for both FL-4 and FL-7 in dye-sensitized solar cells are faster than for devices made using the ruthenium dye N719. We believe that this is a serious limiting factor for devices based on oligothiophenes which, despite showing higher molecular extinction coefficients in the vis-NIR region of the solar spectrum, still cannot challenge the light-to-energy conversion efficiency of N719 or other ruthenium polypyridyl complexes.

Cold-adapted yeasts as producers of cold-active polygalacturonases.

Eight cold-adapted, polygalacturonase-producing yeasts belonging to four species were isolated from frozen environmental samples in Iceland. They were identified as Cystofilobasidium lari-marini, Cystofilobasidium capitatum, Cryptococcus macerans and Cryptococcus aquaticus species by sequence analysis of rDNA regions. Growth behavior of the isolates was investigated. All strains could grow at 2 degrees C. Addition of glucose to pectin-containing culture medium had a repressive effect on enzyme production except for C. aquaticus, which showed increased polygalacturonase activity. Optimal temperature for enzyme production for the Cystofilobasidium strains was 14 degrees C, while that for the Cryptococcus strains was lower. Among the isolates, C. lari-marini S3B produced highest levels of enzyme activity at pH 3.2. Preliminary characterization of the polygalacturonases in the culture supernatant showed the enzyme from Cystofilobasidium strains to be optimally active at 40 degrees C and pH 5, and that from the Cryptococcus strains at 50 degrees C and pH 4. The polygalacturonase from C. macerans started to lose activity after 1 h of incubation at 40 degrees C, while that from the other strains had already lost activity at 30 degrees C. All the strains except C. aquaticus produced isoenzymes of polyglacturonase. In addition to polygalacturonase, the Cystofilobasidium strains produced pectin lyase, C. aquaticus pectin esterase, and C. macerans pectin lyase, pectate lyase and pectin esterase.