1,690 research outputs found
Analytic Kramer kernels, Lagrange-type interpolation series and de Branges spaces
The classical Kramer sampling theorem provides a method for obtaining orthogonal sampling formulas. In particular, when the involved kernel is analytic in the sampling parameter it can be stated in an abstract setting of reproducing kernel Hilbert spaces of entire functions which includes as a particular case the classical Shannon sampling theory. This abstract setting allows us to obtain a sort of converse result and to characterize when the sampling formula associated with an analytic Kramer kernel can be expressed as a Lagrange-type interpolation series. On the other hand, the de Branges spaces of entire functions satisfy orthogonal sampling formulas which can be written as Lagrange-type interpolation series. In this work some links between all these ideas are established
Simulation of High Conversion Efficiency and Open-circuit Voltages Of {\alpha}-si/poly-silicon Solar Cell
The P+ {\alpha}-Si /N+ polycrystalline solar cell is molded using the AMPS-1D
device simulator to explore the new high efficiency thin film poly-silicon
solar cell. In order to analyze the characteristics of this device and the
thickness of N+ poly-silicon, we consider the impurity concentration in the N+
poly-silicon layer and the work function of transparent conductive oxide (TCO)
in front contact in the calculation. The thickness of N+ poly-silicon has
little impact on the device when the thickness varies from 20 {\mu}m to 300
{\mu}m. The effects of impurity concentration in polycrystalline are analyzed.
The conclusion is drawn that the open-circuit voltage (Voc) of P+ {\alpha}-Si
/N+ polycrystalline solar cell is very high, reaching 752 mV, and the
conversion efficiency reaches 9.44%. Therefore, based on the above optimum
parameters the study on the device formed by P+ {\alpha}-Si/N+ poly-silicon is
significant in exploring the high efficiency poly-silicon solar cell.Comment: 8 pages 6figures, 1 table
Molecular and phylogenetic characterization of honey bee viruses, Nosema microsporidia, protozoan parasites, and parasitic mites in China
China has the largest number of managed honey bee colonies, which produce the highest quantity of honey and royal jelly in the world; however, the presence of honey bee pathogens and parasites has never been rigorously identified in Chinese apiaries. We thus conducted a molecular survey of honey bee RNA viruses, Nosema microsporidia, protozoan parasites, and tracheal mites associated with nonnative Apis mellifera ligustica and native Apis cerana cerana colonies in China. We found the presence of black queen cell virus (BQCV), chronic bee paralysis virus (CBPV), deformed wing virus (DWV), Israeli acute paralysis virus (IAPV), and sacbrood virus (SBV), but not that of acute bee paralysis virus (ABPV) or Kashmir bee virus (KBV). DWV was the most prevalent in the tested samples. Phylogenies of Chinese viral isolates demonstrated that genetically heterogeneous populations of BQCV, CBPV, DWV, and A. cerana-infecting SBV, and relatively homogenous populations of IAPV and A. meliifera-infecting new strain of SBV with single origins, are spread in Chinese apiaries. Similar to previous observations in many countries, Nosema ceranae, but not Nosema apis, was prevalent in the tested samples. Crithidia mellificae, but not Apicystis bombi was found in five samples, including one A. c. cerana colony, demonstrating that C. mellificae is capable of infecting multiple honey bee species. Based on kinetoplast-encoded cytochrome b sequences, the C. mellificae isolate from A. c. cerana represents a novel haplotype with 19 nucleotide differences from the Chinese and Japanese isolates from A. m. ligustica. This suggests that A. c. cerana is the native host for this specific haplotype. The tracheal mite, Acarapis woodi, was detected in one A. m. ligustica colony. Our results demonstrate that honey bee RNA viruses, N. ceranae, C. mellificae, and tracheal mites are present in Chinese apiaries, and some might be originated from native Asian honey bees
Glycoprotein Ib activation by thrombin stimulates the energy metabolism in human platelets
<div><p>Thrombin-induced platelet activation requires substantial amounts of ATP. However, the specific contribution of each ATP-generating pathway <i>i</i>.<i>e</i>., oxidative phosphorylation (OxPhos) versus glycolysis and the biochemical mechanisms involved in the thrombin-induced activation of energy metabolism remain unclear. Here we report an integral analysis on the role of both energy pathways in human platelets activated by several agonists, and the signal transducing mechanisms associated with such activation. We found that thrombin, Trap-6, arachidonic acid, collagen, A23187, epinephrine and ADP significantly increased glycolytic flux (3–38 times <i>vs</i>. non-activated platelets) whereas ristocetin was ineffective. OxPhos (33 times) and mitochondrial transmembrane potential (88%) were increased only by thrombin. OxPhos was the main source of ATP in thrombin-activated platelets, whereas in platelets activated by any of the other agonists, glycolysis was the principal ATP supplier. In order to establish the biochemical mechanisms involved in the thrombin-induced OxPhos activation in platelets, several signaling pathways associated with mitochondrial activation were analyzed. Wortmannin and LY294002 (PI3K/Akt pathway inhibitors), ristocetin and heparin (GPIb inhibitors) as well as resveratrol, ATP (calcium-release inhibitors) and PP1 (Tyr-phosphorylation inhibitor) prevented the thrombin-induced platelet activation. These results suggest that thrombin activates OxPhos and glycolysis through GPIb-dependent signaling involving PI3K and Akt activation, calcium mobilization and protein phosphorylation.</p></div
EVALUACIÓN DEL CONOCIMIENTO ENFERMERO EN EL MANEJO AL PACIENTE NEUTROPÉNICO
Objective: To evaluate the nursing staff's knowledge about management of cancer patients with febrile neutropenia. Methodology: An observational descriptive study was carried out with 35 nurses of hospital centers in Havana city, from 2006 to 2008. A structured survey was designed and then applied, with previous consent, to the participating nurses. Results: Out of 35 nurses interviewed, 51.4% have their degree, 54.4% work in institutes, 57.1% perform assistance functions and 37.7% work in oncohematologic services. Work experience in this service is between one and two years. 68.5% of nurses know a lot about neutropenia, 25.7 % know a little, and 5.7 % do not know anything about the topic. Conclusions: The knowledge level was high in the majority, and it was associated with the precedent of having received postgraduate courses regarding Oncology and training from the nurses in the units where they work.Objetivo: Evaluar el conocimiento del personal de enfermería sobre el manejo del paciente oncológico con neutropenia febril. Método: Estudio observacional descriptivo evaluativo con 35 enfermeros pertenecientes a centros hospitalarios de Ciudad de la Habana durante el período 2006 -2008. Se diseño un cuestionario estructurado que fue aplicado con previo consentimiento de los enfermeros participantes. Resultados: De los 35 enfermeros encuestados, el 51.4% son licenciados, 54.4% trabajan en institutos, el 57.1% ejercen funciones asistenciales, y el 37.7% laboran en servicios oncohematologicos. Los años de experiencia de trabajo en el servicio oscilan entre 1 y 2 años. El 68.5% posee mucho conocimiento sobre neutropenia, poco un 25.7% y no tienen conocimientos el 5.7%. Conclusiones: El nivel de conocimiento fue evaluado en su mayoría de mucho, y se asoció al antecedente de haber recibido cursos postgrados sobre Oncología y adiestramientos de los enfermeros en los servicios donde laboran
Polarized recombination of acoustically transported carriers in GaAs nanowires
The oscillating piezoelectric field of a surface acoustic wave (SAW) is employed to transport photoexcited electrons and holes in GaAs nanowires deposited on a SAW delay line on a LiNbO3 crystal. The carriers generated in the nanowire by a focused light spot are acoustically transferred to a second location where they recombine. We show that the recombination of the transported carriers occurs in a zinc blende section on top of the predominant wurtzite nanowire. This allows contactless control of the linear polarized emission by SAWs which is governed by the crystal structure. Additional polarization-resolved photoluminescence measurements were performed to investigate spin conservation during transport
Heavy metal pollution in drinking water - a global risk for human health: A review
Water resources in the world have been profoundly influenced over the last years by human activities, whereby the world is currently facing critical water supply and drinking water quality problems. In many parts of the world heavy metal (HM) concentrations in drinking water are higher than some international guideline values. Discussing about the HM pollution in drinking water, the incorporation of them into the food chain, and their implications as a global risk for the human health, are the objectives of this review. It is known that there are million people with chronic HM poisoning which has become a worldwide public health issue, while 1.6 million children die each year from diseases for which contaminated drinking water is a leading cause. There is also evidence of HM in drinking water that are responsible for causing adverse effect on human health through food chain contamination. A global effort to offering affordable and healthy drinking water most to be launched throughout the world, while various laws and regulations to protect and improve the utilization of drinking water resources should be updated or created throughout the world, including the low income countries; otherwise, the problem of HM-polluted drinking water will be growing because demand for drinking water is still growing such as this problem will become even more pressing in the future. Finally, notwithstanding, additional researches are necessaries about the correlation between HM concentration in drinking water and human diseases, while the development of robust, cheap and sustainable technologies to improve the drinking water quality is necessary.Key words: Groundwater, aquifer, water quality, water pollution, microorganism, water supply, microbial communities, food chain, disease
Efficacy of phage therapy in preclinical models of bacterial infection: a systematic review and meta-analysis.
BACKGROUND
Antimicrobial resistance of bacterial pathogens is an increasing clinical problem and alternative approaches to antibiotic chemotherapy are needed. One of these approaches is the use of lytic bacterial viruses known as phage therapy. We aimed to assess the efficacy of phage therapy in preclinical animal models of bacterial infection.
METHODS
In this systematic review and meta-analysis, MEDLINE/Ovid, Embase/Ovid, CINAHL/EbscoHOST, Web of Science/Wiley, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and Google Scholar were searched from inception to Sept 30, 2021. Studies assessing phage efficacy in animal models were included. Only studies that assessed the efficacy of phage therapy in treating established bacterial infections in terms of survival and bacterial abundance or density were included. Studies reporting only in-vitro or ex-vivo results and those with incomplete information were excluded. Risk-of-bias assessment was performed using the Systematic Review Centre for Laboratory Animal Experimentation tool. The main endpoints were animal survival and tissue bacterial burden, which were reported using pooled odds ratios (ORs) and mean differences with random-effects models. The I2 measure and its 95% CI were also calculated. This study is registered with PROSPERO, CRD42022311309.
FINDINGS
Of the 5084 references screened, 124 studies fulfilled the selection criteria. Risk of bias was high for 70 (56%) of the 124 included studies; therefore, only studies classified as having a low-to-moderate risk of bias were considered for quantitative data synthesis (n=32). Phage therapy was associated with significantly improved survival at 24 h in systemic infection models (OR 0·08 [95% CI 0·03 to 0·20]; I2=55% [95% CI 8 to 77]), skin infection (OR 0·08 [0·04 to 0·19]; I2 = 0% [0 to 79]), and pneumonia models (OR 0·13 [0·06 to 0·31]; I2=0% [0 to 68]) when compared with placebo. Animals with skin infections (mean difference -2·66 [95% CI -3·17 to -2·16]; I2 = 95% [90 to 96]) and those with pneumonia (mean difference -3·35 [-6·00 to -0·69]; I2 = 99% [98 to 99]) treated with phage therapy had significantly lower tissue bacterial loads at 5 ± 2 days of follow-up compared with placebo.
INTERPRETATION
Phage therapy significantly improved animal survival and reduced organ bacterial loads compared with placebo in preclinical animal models. However, high heterogeneity was observed in some comparisons. More evidence is needed to identify the factors influencing phage therapy performance to improve future clinical application.
FUNDING
Swiss National Foundation and Swiss Heart Foundation
Low-energy Pion-nucleon Scattering
This paper contains the results of an analysis of recent low-energy
pion-nucleon scattering experiments. Obtained are phase shifts, the
pion-nucleon coupling constant and an estimate of the Sigma term.Comment: 30 pages, 11 figures, LaTe
Adaptation and Preadaptation of Salmonella enterica to Bile
Bile possesses antibacterial activity because bile salts disrupt membranes, denature proteins, and damage DNA. This study describes mechanisms employed by the bacterium Salmonella enterica to survive bile. Sublethal concentrations of the bile salt sodium deoxycholate (DOC) adapt Salmonella to survive lethal concentrations of bile. Adaptation seems to be associated to multiple changes in gene expression, which include upregulation of the RpoS-dependent general stress response and other stress responses. The crucial role of the general stress response in adaptation to bile is supported by the observation that RpoS− mutants are bile-sensitive. While adaptation to bile involves a response by the bacterial population, individual cells can become bile-resistant without adaptation: plating of a non-adapted S. enterica culture on medium containing a lethal concentration of bile yields bile-resistant colonies at frequencies between 10−6 and 10−7 per cell and generation. Fluctuation analysis indicates that such colonies derive from bile-resistant cells present in the previous culture. A fraction of such isolates are stable, indicating that bile resistance can be acquired by mutation. Full genome sequencing of bile-resistant mutants shows that alteration of the lipopolysaccharide transport machinery is a frequent cause of mutational bile resistance. However, selection on lethal concentrations of bile also provides bile-resistant isolates that are not mutants. We propose that such isolates derive from rare cells whose physiological state permitted survival upon encountering bile. This view is supported by single cell analysis of gene expression using a microscope fluidic system: batch cultures of Salmonella contain cells that activate stress response genes in the absence of DOC. This phenomenon underscores the existence of phenotypic heterogeneity in clonal populations of bacteria and may illustrate the adaptive value of gene expression fluctuations
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