An ice machine adapted into an autonomous photovoltaic system without batteries using a variable-speed drive

The adaptation of a commercially available ice machine for autonomous photovoltaic operation without batteries is presented. In this adaptation a 1040 W(p) photovoltaic array directly feeds a variable-speed drive and a 24 V(dc) source. The drive runs an induction motor coupled by belt-and-pulley to an open reciprocating compressor, while the dc source supplies a solenoid valve and the control electronics. Motor speed and refrigerant evaporation pressure are set aiming at continuously matching system power demand to photovoltaic power availability. The resulting system is a simple integration of robust, standard, readily available parts. It produces 27 kg of ice in a clear-sky day and has ice production costs around US$0.30/kg. Although a few machine features might be specific to Brazil, its technical and economical guidelines are applicable elsewhere. Copyright (C); 2010 John Wiley & Sons, Ltd.

Six-element circuit for maximum power point tracking in photovoltaic-motor systems with variable-frequency drives

A low-cost circuit was developed for stable and efficient maximum power point (MPP) tracking in autonomous photo voltaic-motor systems with variable-frequency drives (VFDs). The circuit is made of two resistors, two capacitors, and two Zener diodes. Its input is the photovoltaic (PV) array voltage and its output feeds the proportional-integral-derivative (PID) controller usually integrated into, the drive. The steady-state frequency-voltage oscillations induced by the circuit were treated in a simplified mathematical model, which was validated by widely characterizing a PV-powered centrifugal pump. General procedures for circuit and controller tuning were recommended based on model equations. The tracking circuit presented here is widely applicable to PV-motor system with VFDs, offering an. efficient open-access technology of unique simplicity. Copyright (C) 2010 John Wiley & Sons, Ltd.

KCNQ Channels Determine Serotonergic Modulation of Ventral Surface Chemoreceptors and Respiratory Drive

Chemosensitive neurons in the retrotrapezoid nucleus (RTN) regulate breathing in response to CO2/H+ changes. Their activity is also sensitive to neuromodulatory inputs from multiple respiratory centers, and thus they serve as a key nexus of respiratory control. However, molecular mechanisms that control their activity and susceptibility to neuromodulation are unknown. Here, we show in vitro and in vivo that KCNQ channels are critical determinants of RTN neural activity. In particular, we find that pharmacological block of KCNQ channels (XE991, 10 mu M) increased basal activity and CO2 responsiveness of RTN neurons in rat brain slices, whereas KCNQ channel activation (retigabine, 2-40 mu M) silenced these neurons. Interestingly, we also find that KCNQ and apamin-sensitive SK channels act synergistically to regulate firing rate of RTN chemoreceptors; simultaneous blockade of both channels led to a increase in CO2 responsiveness. Furthermore, we also show that KCNQ channels but not SK channels are downstream effectors of serotonin modulation of RTN activity in vitro. In contrast, inhibition of KCNQ channel did not prevent modulation of RTN activity by Substance P or thyrotropin-releasing hormone, previously identified neuromodulators of RTN chemoreception. Importantly, we also show that KCNQ channels are critical for RTN activity in vivo. Inhibition of KCNQ channels lowered the CO2 threshold for phrenic nerve discharge in anesthetized rats and decreased the ventilatory response to serotonin in awake and anesthetized animals. Given that serotonergic dysfunction may contribute to respiratory failure, our findings suggest KCNQ channels as a new therapeutic avenue for respiratory complications associated with multiple neurological disorders.

Computational and experimental characterization of a low-cost piezoelectric valveless diaphragm pump

Flow pumps act as important devices in areas such as Bioengineering, Medicine, and Pharmacy, among other areas of Engineering, mainly for delivering liquids or gases at small-scale and precision flow rate quantities. Principles for pumping fluids based on piezoelectric actuators have been widely studied, since they allow the construction of pump systems for displacement of small fluid volumes with low power consumption. This work studies valveless piezoelectric diaphragm pumps for flow generation, which uses a piezoelectric ceramic (PZT) as actuator to move a membrane (diaphragm) up and down as a piston. The direction of the flow is guaranteed by valveless configuration based on a nozzle-diffuser system that privileges the flow in just one pumping direction. Most research efforts on development of valveless flow pump deal either with computational simulations based on simplified models or with simplified physical approaches based on analytical models. The main objective of this work is the study of a methodology to develop a low-cost valveless piezoelectric diaphragm flow pump using computational simulations, parametric study, prototype manufacturing, and experimental characterization. The parametric study has shown that the eccentricity of PZT layer and metal layer plays a key role in the performance of the pump.

Association of Proton Pump Inhibitor Use on Cardiovascular Outcomes With Clopidogrel and Ticagrelor Insights From the Platelet Inhibition and Patient Outcomes Trial

Background-The clinical significance of the interaction between clopidogrel and proton pump inhibitors (PPIs) remains unclear. Methods and Results-We examined the relationship between PPI use and 1-year cardiovascular events (cardiovascular death, myocardial infarction, or stroke) in patients with acute coronary syndrome randomized to clopidogrel or ticagrelor in a prespecified, nonrandomized subgroup analysis of the Platelet Inhibition and Patient Outcomes (PLATO) trial. The primary end point rates were higher for individuals on a PPI (n = 6539) compared with those not on a PPI (n = 12 060) at randomization in both the clopidogrel (13.0% versus 10.9%; adjusted hazard ratio [HR], 1.20; 95% confidence interval [CI], 1.04 -1.38) and ticagrelor (11.0% versus 9.2%; HR, 1.24; 95% CI, 1.07-1.45) groups. Patients on non-PPI gastrointestinal drugs had similar primary end point rates compared with those on a PPI (PPI versus non-PPI gastrointestinal treatment: clopidogrel, HR, 0.98; 95% CI, 0.79-1.23; ticagrelor, HR, 0.89; 95% CI, 0.73-1.10). In contrast, patients on no gastric therapy had a significantly lower primary end point rate (PPI versus no gastrointestinal treatment: clopidogrel, HR, 1.29; 95% CI, 1.12-1.49; ticagrelor, HR, 1.30; 95% CI, 1.14-1.49). Conclusions-The use of a PPI was independently associated with a higher rate of cardiovascular events in patients with acute coronary syndrome receiving clopidogrel. However, a similar association was observed between cardiovascular events and PPI use during ticagrelor treatment and with other non-PPI gastrointestinal treatment. Therefore, in the PLATO trial, the association between PPI use and adverse events may be due to confounding, with PPI use more of a marker for, than a cause of, higher rates of cardiovascular events.

Low levels of adherence with proton pump inhibitor therapy contribute to therapeutic failure in gastroesophageal reflux disease

To assess adherence to proton pump inhibitor (PPI) treatment and associated variables in patients with gastroesophageal reflux disease (GERD). Cross-sectional and prospective comprising 240 consecutive adult patients, diagnosed with GERD for whom continuous use of standard or double dose of omeprazole had been prescribed. Patients were ranked as ne-GERD (162: 67.5%) or e-GERD classified according to the Los Angeles classification as A (48:20.0%), B (21:8.6%), C (1:0.5%), D (1:0.5%), and Barrett's esophagus (7:2.9%). The Morisky questionnaire was applied to assess adherence to therapy and a GERD questionnaire to assess symptoms and their impact. Adherence was correlated with demographics, cotherapies, comorbidities, treatment duration, symptoms scores, endoscopic findings, and patient awareness of their disease. 126 patients (52.5%) exhibited high level of adherence and 114 (47.5%) low level. Youngers (P= 0.002) or married (O.R. 2.41, P= 0.03 vs. widowers) patients had lower levels of adherence; symptomatic patients exhibited lower adherence (P= 0.02). All other variables studied had no influence on adherence. Patients with GERD attending a tertiary referral hospital in Sao Paulo exhibited a high rate of low adherence to the prescribed PPI therapy that may play a role in the therapy failure. Age <60 years, marital status and being symptomatic were risk factors for low adherence.

Analysis of Electrostatic Turbulence Drive in Texas Helimak.

Plasma turbulence and particle transport in Texas Helimak change with the radial electric field profile modified by an external voltage bias. When the bias is positive, the turbulence shows enhanced level and broadband spectra with extreme events, similar to the turbulence in tokamak scrape-‐off layer. However, negative bias reduces the turbulence level and decreases the spectrum widths. Moreover, for negative biased shots, the particle transport is strongly affected by a wave particle resonant interaction. On the other hand, for positive bias values, the plasma presents a transport barrier in the reversed shear flow region.

Polyphase drive systems configuration aiming EMI mitigation

Topologies of motor drive systems are studied, aiming the reduction of common-mode (CM) currents. Initially, the aspects concerning the CM currents circulation are analysed. The reason of common-mode voltages generation, the circulating paths for the resulting CM currents and their effects are discussed. Then, a non-conventional drive system configuration is proposed in order to reduce the CM currents and their effects. This configuration comprehends a non-conventional inverter module wired to a motor with an unusual connection. The cables arrangement differs from the standard solution, too. The proposed topology is compared with other ones, like the active circuit for common-mode voltages compensation. The contribution of the configuration to the reduction of CM voltages and currents and their related interferences are evaluated, based on numerical simulations. Some results are presented and discussed regarding the suitability of the proposed configuration as a potential solution to reduce the CM currents effects, when the state of art and implementation cost of drives are taken into account.

Zooplankton, micronekton and biological pump: Beyond the mesopelagic zone

[EN] Migrant biota transports carbon to the mesopelagic zone due to their feeding at the shallower layers and their defecation, respiration, excretion and mortality at depth. The so-called active flux has been considered a small number compared to gravitational sinking. Recent assessments in subtropical waters show an important effect due to predation by interzonal diel vertical migrants (DVMs). The consumption and subsequent transport of epipelagic zooplankton by DVMs (mainly micronekton) to the mesopelagic zone seemed similar to the mean gravitational export. However, the consequences of this active transport to the bathypelagic zone are almost unknown. Here, we show the effect of the Atlantic and Pacific equatorial upwelling systems on the vertical distribution of acoustic backscatter from the surface to bathypelagic depths. The enhancement of the acoustic signal below the upwelling zone was observed to reach 4000 m depth, coinciding with high abundances and activity of bacteria at those depths. The results suggest an active carbon transport from the epipelagic driven by zooplankton and micronekton, enhancing the efficiency of the biological pump and giving an insight about the fate of an increased productivity at the shallower layers of the ocean

Sistema di fatturazione collegato a Google Drive

L'obbiettivo della tesi è quello di sviluppare una semplice web application per la creazione di fatture. La caratteristica principale è l'integrazione delle funzionalità di Google Drive permettendo all'utente di archiviare e condividere con pochi click le fatture con i clienti. L'utente potrà creare, personalizzare, salvare, archiviare e condividere le proprie ricevute in tempo reale. In questo documento verrà analizzato il processo di sviluppo del software che comprenderà: analisi dei requisiti, progettazione, sviluppo (scelte implementative), test e sviluppi futuri. Verranno anche documentate le tecnologie utilizzate al fine di raggiungere il prodotto finale.

Nanomechanics to drive stem cells in injured tissues: insights from current research and future perspectives

Stem cells reside within tissue, ensuring its natural ability to repair an injury. They are involved in the natural repair of damaged tissue, which encompasses a complex process requiring the modulation of cell survival, extracellular matrix turnover, angiogenesis, and reverse remodeling. To date, the real reparative potential of each tissue is underestimated and noncommittal. The assessment of the biophysical properties of the extracellular environment is an innovative approach to better understand mechanisms underlying stem cell function, and consequently to develop safe and effective therapeutic strategies replacing the loss of tissue. Recent studies have focused on the role played by biomechanical signals that drive stem cell death, differentiation, and paracrinicity in a genetic and/or an epigenetic manner. Mechanical stimuli acting on the shape can influence the biochemistry and gene expression of resident stem cells and, therefore, the magnitude of biological responses that promote the healing of injured tissue. Nanotechnologies have proven to be a revolutionary tool capable of dissecting the cellular mechanosensing apparatus, allowing the intercellular cross-talk to be decoded and enabling the reparative potential of tissue to be enhanced without manipulation of stem cells. This review highlights the most relevant findings of stem cell mechanobiology and presents a fascinating perspective in regenerative medicine.

Sensor-augmented pump therapy lowers HbA(1c) in suboptimally controlled Type?1 diabetes; a randomized controlled trial

To investigate the efficacy of sensor-augmented pump therapy vs. multiple daily injection therapy in patients with suboptimally controlled Type 1 diabetes.

Do fungal pathogens drive density-dependent mortality in established seedlings of two dominant African rain forest trees?

Where one or a few tree species reach local high abundance, different ecological factors may variously facilitate or hinder their regeneration. Plant pathogens are thought to be one of those possible agents which drive intraspecific density-dependent mortality of tree seedlings in tropical forests. Experimental evidence for this is scarce, however. In an African rain forest at Korup, we manipulated the density of recently established seedlings (~5–8 wk old; low vs. high-density) of two dominant species of contrasting recruitment potential, and altered their exposure to pathogens using a broad-spectrum fungicide. Seedling mortality of the abundantly recruiting subcanopy tree Oubanguia alata was strongly density-dependent after 7 mo, yet fungicide-treated seedlings had slightly higher mortality than controls. By contrast, seedling mortality of the poorly recruiting large canopy-emergent tree Microberlinia bisulcata was unaffected by density or fungicide. Ectomycorrhizal colonization of M. bisulcata was not affected by density or fungicide either. For O. alata, adverse effects of fungicide on its vesicular arbuscular mycorrhizas may have offset any possible benefit of pathogen removal. We tentatively conclude that fungal pathogens are not a likely major cause of density dependence in O. alata, or of early post-establishment mortality in M. bisulcata. They do not explain the latter's currently very low recruitment rate at Korup.