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Artykuły w czasopismach na temat "SENSITIVE QAC"
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Grillitsch, B., O. Gans, N. Kreuzinger, S. Scharf, M. Uhl i M. Fuerhacker. "Environmental risk assessment for quaternary ammonium compounds: a case study from Austria". Water Science and Technology 54, nr 11-12 (1.12.2006): 111–18. http://dx.doi.org/10.2166/wst.2006.840.
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Quaternary ammonium compounds (QAC) are widely used as disinfectants, biocides, and detergents, among a variety of other applications. The cationic surface-activity of QAC determines their potential to act as a biocide on both target and non-target organisms. This study aims to provide a broad-based environmental risk characterization and evaluation for selected QAC with particular focus on the situation in Austrian rivers. A modular study design was employed involving environmental exposure characterization, QAC fate and effect analysis in wastewater, ecotoxicological effect characterization, and environmental risk evaluation. A wide array of Austrian surface waters and wastewater effluents were screened for the selected key compounds, benzalkonium chlorides and dialkyldimethylammonium chlorides with different C-chain lengths. Ecotoxicological effect characterization was based on both microbiotests for a set of representative aquatic organisms and a literature review. For risk evaluation, the PEC/PNEC ratio was above 1 for some rivers. Notably, small rivers with a high particulate matter were contaminated with QAC in the case of high water incidents. Hence, for the Austrian sites studied, a QAC-derived risk to sensitive aquatic non-target organisms could not be excluded.
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Antosik, Adrian Krzysztof, Karolina Mozelewska, Magdalena Zdanowicz, Konrad Gziut i Piotr Miądlicki. "Organophilized Montmorillonites as Fillers for Silicone Pressure-Sensitive Adhesives". Materials 16, nr 3 (19.01.2023): 950. http://dx.doi.org/10.3390/ma16030950.
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In the presented work, organophilized montmorillonites (OMMT) with selected quaternary ammonium compounds (QAC) with different chemical structure ((trioctylmethylammonium chloride—A336, dimethyloctadecyl[3-trimethoxysilyl)propyl]ammonium chloride—D, cetyltrimethylammonium bromide—CTAB, 2-methacryloxyethyltrimethylammonium chloride—MOA) were obtained and used as fillers for physically modified silicone pressure-sensitive adhesives (Si-PSA). Before OMMT addition into Si-PSA matrix, they were analyzed via TGA and XRD techniques. Type of chemical structure of QAC affected d-spacing of OMMT. New self-adhesive materials were obtained based on prepared Si-PSA compositions by adding the obtained fillers to the polymer matrix. New tapes exhibit a good level of useful properties as adhesion, cohesion, and tack—the values did not change or slightly decreased; in addition, the tapes with addition of OMMT showed high thermal resistance reaching the measuring limit of the test equipment—to 225 °C.
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Jiang, Danyang, Honghui Chen i Fei Cai. "Exploiting Query’s Temporal Patterns for Query Autocompletion". Mathematical Problems in Engineering 2017 (2017): 1–8. http://dx.doi.org/10.1155/2017/7490879.
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Query autocompletion (QAC) is a common interactive feature of web search engines. It aims at assisting users to formulate queries and avoiding spelling mistakes by presenting them with a list of query completions as soon as they start typing in the search box. Existing QAC models mostly rank the query completions by their past popularity collected in the query logs. For some queries, their popularity exhibits relatively stable or periodic behavior while others may experience a sudden rise in their query popularity. Current time-sensitive QAC models focus on either periodicity or recency and are unable to respond swiftly to such sudden rise, resulting in a less optimal QAC performance. In this paper, we propose a hybrid QAC model that considers two temporal patterns of query’s popularity, that is, periodicity and burst trend. In detail, we first employ the Discrete Fourier Transform (DFT) to identify the periodicity of a query’s popularity, by which we forecast its future popularity. Then the burst trend of query’s popularity is detected and incorporated into the hybrid model with its cyclic behavior. Extensive experiments on a large, real-world query log dataset infer that modeling the temporal patterns of query popularity in the form of its periodicity and its burst trend can significantly improve the effectiveness of ranking query completions.
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Sidhu, Maan Singh, Even Heir, Truls Leegaard, Karianne Wiger i Askild Holck. "Frequency of Disinfectant Resistance Genes and Genetic Linkage with β-Lactamase Transposon Tn552 among Clinical Staphylococci". Antimicrobial Agents and Chemotherapy 46, nr 9 (wrzesień 2002): 2797–803. http://dx.doi.org/10.1128/aac.46.9.2797-2803.2002.
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ABSTRACT A total of 61 strains of Staphylococcus aureus and 177 coagulase-negative staphylococcal strains were isolated from the blood of patients with bloodstream infections and from the skin of both children under cancer treatment and human immunodeficiency virus-positive patients. The MIC analyses revealed that 118 isolates (50%) were resistant to quaternary ammonium compound-based disinfectant benzalkonium chloride (BC). The frequencies of resistance to a range of antibiotics were significantly higher among BC-resistant staphylococci than among BC-sensitive staphylococci. Of 78 BC-resistant staphylococcal isolates, plasmid DNA from 65 (83%), 2 (3%), 43 (55%), and 15 (19%) isolates hybridized to qacA or -B (qacA/B), qacC, blaZ, and tetK probes, respectively. The qacA/B and blaZ probes hybridized to the same plasmid in 19 (24%) staphylococcal strains. The plasmids harboring both qacA/B and blaZ genes varied from approximately 20 to 40 kb. The Staphylococcus epidermidis Fol62 isolate, harboring multiresistance plasmid pMS62, contained qacA/B and blaZ together with tetK. Molecular and genetic studies indicated different structural arrangements of blaZ and qacA/B, including variable intergenic distances and transcriptional directions of the two genes on the same plasmid within the strains. The different organizations may be due to the presence of various genetic elements involved in cointegration, recombination, and rearrangements. These results indicate that qac resistance genes are common and that linkage between resistance to disinfectants and penicillin resistance occurs frequently in clinical isolates in Norway. Moreover, the higher frequency of antibiotic resistance among BC-resistant strains indicates that the presence of either resistance determinant selects for the other during antimicrobial therapy and disinfection in hospitals.
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He, Gui-Xin, Michael Landry, Huizhong Chen, Conner Thorpe, Dennis Walsh, Manuel F. Varela i Hongmiao Pan. "Detection of benzalkonium chloride resistance in community environmental isolates of staphylococci". Journal of Medical Microbiology 63, nr 5 (1.05.2014): 735–41. http://dx.doi.org/10.1099/jmm.0.073072-0.
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We isolated a total of 653 strains from 64 community environmental samples in Massachusetts, USA. Among these isolates, 9.65 % (63 strains) were benzalkonium chloride (BC)-resistant staphylococci. All BC-resistant strains were collected from surfaces upon which antibacterial wipes or antibacterial sprays containing 0.02–0.12 % BC had frequently been used in the fitness centres. However, isolates from surfaces upon which antibacterial wipes or antibacterial sprays had not been used were all sensitive to BC. All BC-resistant strains were also resistant to erythromycin, penicillin and ampicillin. In addition, 51 strains showed resistance to cetyltrimethylammonium bromide (CTAB), 15 strains showed resistance to chloramphenicol, 12 strains showed resistance to ciprofloxacin and four strains showed resistance to meticillin. Resistance gene analysis demonstrated that 41 strains contained qacA/B, 30 strains had qacC, 25 strains contained qacG, 16 strains had qacH and eight strains contained qacJ. These data indicate that application of BC is associated with environmental staphylococcal antimicrobial resistance.
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Ibrahim, Waleed A., Sherif A. Marouf, Ahmed M. Erfan, Soad A. Nasef i Jakeen K. El Jakee. "The occurrence of disinfectant and antibiotic-resistant genes in Escherichia coli isolated from chickens in Egypt". Veterinary World 12, nr 1 (styczeń 2019): 141–45. http://dx.doi.org/10.14202/vetworld.2019.141-145.
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Aim: This work aimed to determine the occurrence of antibiotic and disinfectant resistance genes in Escherichia coli isolated from chickens in Egypt. Materials and Methods: Organs (liver, lung, heart, yolk sac, and bone marrow) of 1500 chicken samples were collected from diseased chickens suffered from colibacillosis with PM findings as CRD, diarrhea and omphalitis from different governorates of Egypt as: Giza, EL-Bahira, Fayoum, El-Dakahlia, El-Ismalia, and El-Sharkia during 2015-2016. These samples were labeled and transported immediately on ice to the Reference laboratory for quality control on poultry production (RLQP). The samples were cultured onto MacConkey agar and Eosin Methylene Blue Agar. Isolation and identification of the E. coli were performed based on morphology, cultural, staining, and biochemical properties. Antimicrobial resistance test was carried out using disk diffusion method. The PCR employing tetA, qacED1 and qacA/B were carried out for detection of these genes in isolated E.coli. Results: The prevalence of E. coli in chicken was 34%. Predominant serotypes of E. coli which serologically identified were O128, O111, O44, O158, and O2. Antibiotic susceptibility test of E. coli revealed that 100% of isolates were resistant to ampicillin, erythromycin, and sulfamethoxazole-trimethoprim, while 73.53% and 38.23% of them were sensitive for colistin sulfate and levofloxacin, respectively. Antibiotic resistance genes as tetA gene were tested for isolated E. coli and detected by incidence rate of 91.18%. qac resistance genes resembling as qacED1 and qacA/B genes were detected in isolated E. coli 70.6% and 14.7%, respectively. Conclusion: E. coli isolated from chickens in Egypt was carried qac and antibiotic-resistant genes that affect the poultry industry.
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Biswas, Saswati, i Indranil Biswas. "Role of VltAB, an ABC Transporter Complex, in Viologen Tolerance inStreptococcus mutans". Antimicrobial Agents and Chemotherapy 55, nr 4 (31.01.2011): 1460–69. http://dx.doi.org/10.1128/aac.01094-10.
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ABSTRACTStreptococcus mutans, a Gram-positive organism, is the primary causative agent in the formation of dental caries in humans. To persist in the oral cavity,S. mutansmust be able to tolerate rapid environmental fluctuations and exposure to various toxic chemicals. However, the mechanisms underlying the ability of this cariogenic pathogen to survive and proliferate under harsh environmental conditions remain largely unknown. Here, we wanted to understand the mechanisms by whichS. mutanswithstands exposure to methyl viologen (MV), a quaternary ammonium compound (QAC) that generates superoxide radicals in the cell. To elucidate the essential genes for MV tolerance, screening of ∼3,500 mutants generated by ISS1mutagenesis, revealed 15 MV-sensitive mutants. Among them, five and four independent insertions had occurred in SMU.905 and SMU.906 genes, respectively. These two genes are appeared to be organized in an operon and encode a putative ABC transporter complex; we designated the genes asvltAandvltB, forviologentransporter. To verify our results,vltAwas deleted by using an antibiotic resistance marker; the mutant was just as sensitive to MV as the ISS1insertion mutants. Furthermore,vltAandvltBmutants were also sensitive to other viologen compounds such as benzyl and ethyl viologens. Complementation assays were also carried out to confirm the role of VltA and VltB in viologen tolerance. Sensitivity to various drugs, including a wide range of QACs, was evaluated. It appears that a functional VltA is also required for full resistance toward acriflavin, ethidium bromide, and safranin; all are well-known QACs. These results indicate that VltA/B constitute a heterodimeric multidrug efflux pump of the ABC family. BLAST-P analysis suggests that homologs of VltA/B are widely present in streptococci, enterococci, and other important Gram-positive pathogens.
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Hanczvikkel, Adrienn, András Víg i Ákos Tóth. "Survival capability of healthcare-associated, multidrug-resistant bacteria on untreated and on antimicrobial textiles". Journal of Industrial Textiles 48, nr 7 (24.01.2018): 1113–35. http://dx.doi.org/10.1177/1528083718754901.
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Healthcare-associated infections are of global concern, and textiles can contribute to the transmission of pathogens. In this study, we examined quantitatively the survival capability of 60 multidrug-resistant bacterial strains from four species ( Klebsiella pneumoniae, Acinetobacter baumannii, Staphylococcus aureus and Enterococcus faecium) on untreated cotton textile in clinically relevant incubation periods. We determined the antibacterial efficiency of textiles treated either with quaternary ammonium compound (QAC)-containing Sanitized T99-19 liquid (50 m/m% Dimethyltetradecyl (3-(trimethoxysilyl)propyl) ammonium-chloride) or with silver salt-containing Sanitized T27-22 Silver liquid (2 m/m% AgCl and 8 m/m% TiO2) as well. Finally, we compared the results of the healthcare-associated, multidrug-resistant strains and antibiotic-sensitive, quality control standard strains (ATCC 25922, ATCC 11105 Escherichia coli, and ATCC 25923, ATCC 6538 Staphylococcus aureus) often used in antimicrobial efficiency tests. The results revealed that all investigated multidrug-resistant bacteria are able to survive on untreated cotton textile and pose health risk in hospitals. During one day the T27-22-Silver-treated textile was able to eliminate most of the Gram-positive pathogens, reducing the risk of cross-contamination, but none of the examined agents destroyed the multidrug-resistant, Gram-negative isolates. The antibiotic-susceptible and the multidrug-resistant Staphylococcus aureus strains had similar survival capability and biocide-tolerance, while the risk of infections caused by multidrug-resistant, Gram-negative pathogens could be extremely underestimated using only ATCC Escherichia coli standard strains. Our results also draw attention to the careful evaluation of antimicrobial efficiency tests and indicate that a significant reduction of bacterial count does not necessarily mean significant antibacterial efficiency that would be suitable to avoid infections.
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Soloski, M. J., A. Lattimore, D. Hereld, J. L. Krakow, M. G. Low i G. Einhorn. "Further characterization of the membrane anchor found on the tissue-specific class I molecule Qa2." Journal of Immunology 140, nr 11 (1.06.1988): 3858–66. http://dx.doi.org/10.4049/jimmunol.140.11.3858.
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Abstract Previous studies have determined that various Qa2 serologic determinants can be removed from the surface of spleen cells by treatment with a phospholipase C. Our studies have determined that the class I molecule Qa2, expressed on the surface of spleen cells and activated T cells, behaves as an integral membrane protein based on its ability to associate with detergent micelles. Studies utilizing two purified phospholipase C have revealed that although most (90 to 95%) of the Qa2 molecules expressed on the surface of resting spleen cells are released as intact 40-kDa polypeptides associated with beta 2-microglobulin, activated T cells contain a major cell subpopulation expressing lipase-resistant Qa2 molecules. Flow cytometric analysis revealed that L3T4+-activated T cells expressed lipase-sensitive Qa2 molecules, whereas Lyt-2+ cells express lipase-resistant forms of the Qa2 molecule. The relationship between the secreted form of the Qa2 molecule and the lipase-generated soluble Qa2 molecule was investigated. Based on SDS-PAGE analysis, the secreted Qa2 molecules has a Mr of 39 kDa whereas the cell surface form released from either resting spleen or activated T cells by phosphatidylinositol-specific phospholipase C has a Mr of approximately equal to 40 kDa. Furthermore, the secreted Qa2 molecule lacks an epitope, cross-reacting determinant, often present on lipase-solubilized cell surface molecules. Thus, based on serologic and biochemical criteria, the soluble Qa2 molecules generated by an exogenous phospholipase C and the secreted Qa2 molecule are structurally distinct.
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Bardasheva, Alevtina, Artem Tikunov, Yuliya Kozlova, Elena Zhirakovskaia, Valeriya Fedorets, Natalya Fomenko, Tatyana Kalymbetova i in. "Antibiotic Resistance and Pathogenomics of Staphylococci Circulating in Novosibirsk, Russia". Microorganisms 9, nr 12 (30.11.2021): 2487. http://dx.doi.org/10.3390/microorganisms9122487.
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A total of 394 strains of staphylococci found in humans and pets in Novosibirsk, Siberian Russia, were characterized in terms of antibiotic resistance and corresponding genes. Two coagulase-positive and 17 coagulase-negative species were identified. The majority of isolates, with the exception of S. haemolyticus and hospital S. epidermidis isolates, were sensitive to most of the tested antibiotics, and isolates from pets displayed the lowest level of resistance. Nevertheless, methicillin-resistant (MRS) and/or multidrug-resistant (MDR) isolates were found in all prevailed species, including coagulase-negative. A set of genes corresponding to the detected resistance was identified: mecA (beta-lactam resistance), aac(6′)-Ie-aph(2″)-Ia, aph(3′)-IIIa, ant(4′)-Ia (aminoglycoside-modifying enzymes), ermA/ermC, and msrA (macrolide resistance). Complete genome analysis for ten MDR S. epidermidis and five MDR S. haemolyticus isolates revealed additional antibiotic resistance genes mphC, qacA/qacB, norA, dfrC/dfrG, lnuA, BseSR, and fosB. NorA, dfrC, and fosB were present in all S. epidermidis genomes, whereas mphC and msrA were identified in all S. haemolyticus ones. All investigated MDR S. epidermidis and four of five S. haemolyticus strains were moderate or strong biofilm producers, whereas multiple genes responsible for this function and for virulence and pathogenicity were identified mostly in S. epidermidis, but were less frequently represented in S. haemolyticus.
Rozprawy doktorskie na temat "SENSITIVE QAC"
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Pollard, Frederick. "Sensitive skin for robotics". Thesis, University of Bath, 2011. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.558848.
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This thesis explores two novel ways of reducing the data complexity of tactile sensing. The thesis begins by examining the state-of-the art in tactile sensing, not only examining the sensor construction and interpretation of data but also the motivation for these designs. The thesis then proposes two methods for reducing the complexity of data in tactile sensing. The first is a low-power tactile sensing array exploiting a novel application of a pressure-sensitive material called quantum tunnelling composite. The properties of this material in this array form are shown to be beneficial in robotics. The electrical characteristics of the material are also explored. A bit-based structure for representing tactile data called Bitworld is then defined and its computational performance is characterised. It is shown that this bit-based structure outperforms floating-point arrays by orders of magnitude. This structure is then shown to allow high-resolution images to be produced by combining low resolution sensor arrays with equivalent functional performance to a floating-point array, but with the advantages of computational efficiency. Finally, an investigation into making Bitworld robust in the presence of positional noise is described with simulations to verify that such robustness can be achieved. Overall, the sensor and data structure described in this thesis allow simple, but effective tactile systems to be deployed in robotics without requiring a significant commitment of computational or power resources on the part of a robot designer.
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Truman, Andrew. "Position-sensitive scintillation counters". Thesis, University of Southampton, 1996. https://eprints.soton.ac.uk/399480/.
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Gowdy, Stephen J. "Position sensitive detectors in GaAs". Thesis, University of Glasgow, 1987. http://theses.gla.ac.uk/1625/.
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Presented in this thesis is a summary of the development of gallium arsenide position sensitive detectors. These are aimed at various applications with the original motivation being experimental particle physics. An account is given of basic semiconductor physics relevant to particle detectors. A review of electronics applicable to reading out charged signals from semiconductor detectors is included. Applications of gallium arsenide X-ray detectors are described together with results from a Monte-Carlo simulation of the spectrum obtained from an X-ray source. The design, fabrication and laboratory testing of detectors is presented for pixel and microstrip detectors and other test structures. Test beam results are also presneted for pixel and microstrip detectors. An introduction to ATLAS detector simulation is also given, with examples of detector descriptions for the GaAs Forward Semiconductor Tracker. Results from a generator level study of b-jets from the process Hbb and predictions of influences in the Forward Tracker are also given.
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Umatova, Zarina. "A sensitive device for SThM quantifiation". Thesis, University of Glasgow, 2018. http://theses.gla.ac.uk/30924/.
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This thesis describes an experimental study of the heat transport between the tip of a Scanning Thermal Microscope –Atomic Force Microscope (SThM-AFM) and nanofabricated sample. SThM is one of the most flexible tools available for measuring thermal transport at the nanoscale. However, heat transfer between the probe and sample has a complicated nature as it depends on different parameters such as the nature of the surrounding gas (pressure, temperature, degree of humidity), and that of the mechanical contact between probe tip and sample (surface roughness and topography, mechanical properties of the tip surface and sample surface and the force applied). So understanding the heat flow between tip and sample requires careful study of all of these parameters. Thus quantification of tip and sample thermal contact is a key problem in the interpretation of SThM measurements. In this work the fabrication of devices to quantify SThM tip and sample surface thermal resistance in one single contact are presented. The fabrication was performed using lithographic nanofabrication and MEMS technology. Thermally grown silicon dioxide was chosen as a membrane material for all devices due to its low thermal and electrical conductivity and ease of fabrication.
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Deshpande, Amogh. "Topics in risk-sensitive stochastic control". Thesis, University of Warwick, 2014. http://wrap.warwick.ac.uk/67915/.
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This thesis consists of three topics whose over-arching theme is based on risk sensitive stochastic control. In the �first topic (chapter 2), we study a problem on benchmark out-performance. We model this as a zero-sum risk-sensitive stochastic game between an investor who as a player wants to maximize the risk-sensitive criterion while the other player ( a stochastic benchmark) tries to minimize this maximum risk-sensitive criterion. We obtain an explicit expression for the strategies for both these two players. In the second topic (chapter 3), we consider a finite horizon risk-sensitive asset management problem. We study it in the context of a zero-sum stochastic game between an investor and the second player called the "market world" which provides a probability measure. Via this game, we connect two (somewhat) disparate areas in stochastics; namely, stochastic stability and risk-sensitive stochastic control in mathematical finance. The connection is through the Follmer-Schweizer minimal martingale measure. We discuss the impact of this measure on the investor's optimal strategy. In the third topic (chapter 4), we study the sufficient stochastic maximum principle of semi-Markov modulated jump diffusion. We study its application in the context of a quadratic loss minimization problem. We also study the finite-horizon risk-sensitive optimization in relation to the underlying sufficient stochastic maximum principle of a semi-markov modulated diffusion.
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Holmes, James Wright. "Optical surface pressure measurement using pressure sensitive paint". Thesis, University of Southampton, 2000. https://eprints.soton.ac.uk/47083/.
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Kakande, Joseph. "Phase sensitive parametric amplifiers and their applications". Thesis, University of Southampton, 2012. https://eprints.soton.ac.uk/336325/.
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Phase sensitive amplification (PSA) is a remarkably powerful tool if implemented correctly - it allows amplification with a noise figure lower than quantum mechanics normally dictates, and also allows the development of systems that coherently process the phase of their optical inputs. PSA at infrared wavelengths can be achieved using second or third order optical nonlinearities - indeed the first demonstrations of PSA utilised degenerate three photon mixing in bulk crystals, allowing the observation of effects such as quantum quadrature squeezing. This PhD research project was aimed at translating the fascinating science of PSAs into applications, based on Kerr nonlinearity in optical fibres, capable of being deployed in modern core optical networks runnning at 40 Gbit/s and higher. This objective was an integral part of the European Union FP7 project PHASORS. Studies, both theoretical and experimental, were carried out on wideband non-degenerate PSAs. The inline cascaded fiber optic parametric amplifier (FOPA), in which a first phase insensitive FOPA is used to generate phase locked signal-idler pairs, followed by a second FOPA in which PSA takes place, was used to experimentally demonstrate PSA gain characteristics in linear and saturated modes of operation, with PSA obtained over 20 nm in the telecom C-band. Focus was then re-directed towards applying a dual pump PSA to DPSK regeneration. The amplitude and phase limiting characteristics of these devices were experimentally studied, in particular revealing that amplitude saturation arises due to an interplay between input phase and nonlinear phase matching along the nonlinear fibre. This feature was used to identify a regime of operation for DPSK regeneration combining simultaneous phase and amplitude regeneration. A practical DPSK regenerator based on a degenerate dual pump phase sensitive FOPA was built. The device advanced the state of the art by incorporating a pump synthesis stage that allowed black-box operation. Detailed measurements using noise sources with varying frequency distributions in both amplitude and in phase, are presented, and the ability of the system to improve the phase and amplitude characteristics of signals at its input was verified. Also presented are results showing the regenerator installed in the middle of an 800 km dark fiber link. Finally, a novel scheme was proposed and demonstrated that utilised parametric mixing to perform arbitrary phase quantization. This relied on the coherent addition of an M-level PSK signal with a conjugated (M-1)th phase harmonic, scaled by a coefficient m, to achieve M-level phase quantization. The concept was successfully demonstrated with QPSK data signals at 56 Gbaud, as well as used to quantize lower bandwidth test signals from 2 to 6 phase levels.
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Montgomery, Rachel Ann. "A position sensitive photon detector for the CLAS12 ring imaging Čerenkov application". Thesis, University of Glasgow, 2013. http://theses.gla.ac.uk/4570/.
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The upgrade of the Continuous Electron Beam Accelerator Facility (CEBAF) Large Acceptance Spectrometer (CLAS) to CLAS12 will offer unique possibilities to study the strong interaction and the internal nucleon dynamics. For this, excellent hadron identification over its full kinematic range is essential and a Ring Imaging CHerenkov detector (RICH) has been proposed for installation into CLAS12 to achieve this. This thesis describes studies performed towards the selection of a photon detector for use in the CLAS12 RICH, which will be a crucial component for the success of the RICH performance. MultiAnode PhotoMultiplier Tubes (MAPMTs) have been selected as the most promising photon detectors for the CLAS12 RICH. A high-precision laser test-stand was developed to characterise candidate MAPMTs and the results were used to determine the Hamamatsu H8500 MAPMT as the optimal device. Throughout the laser tests the H8500 MAPMT proved to be single photon sensitive as demanded, the spatial resolution was found to satisfy the required value of less than 1cm by 1cm and the device exhibited sufficiently low crosstalk levels of less than 3%. The response and crosstalk of the device showed a dependency upon the MAPMT construction, the magnitude of which was shown to be negligible and overall the H8500 provides a plane of suitable uniformity to satisfy the imaging functionality of the CLAS12 RICH. To further confirm the H8500 MAPMT choice, its performance in response to Cherenkov light within two prototype setups was evaluated. First a small-scale prototype was designed and constructed, incorporating one H8500 MAPMT to image Cherenkov rings created by cosmic muons traversing aerogel radiators. Extraction of the results required full understanding of the device based upon calibrations made with the laser tests. The prototype was also simulated in detail, allowing for a model description of the MAPMT to be validated. Secondly, 28 H8500 MAPMTs were used in a large-scale prototype to image Cherenkov rings produced by mixed hadrons traversing aerogel radiators, to evaluate their performance in a geometry and an environment similar to that expected in the CLAS12 RICH. Both prototypes revealed that the H8500 MAPMT can be used to successfully detect the required 7 photons per Cherenkov event to achieve pion/kaon separation in the CLAS12 RICH. Furthermore, a pion/kaon separation of more than 3 sigma at 6GeV/c was observed through a preliminary analysis of data extracted with the large-scale prototype. The prototype studies also confirmed the low-noise behaviour of the H8500 MAPMT. As a result of the laser test-stand and prototype tests, the choice of the H8500 MAPMT as the photon detector for the CLAS12 RICH was validated.
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Gecevičius, Mindaugas. "Polarization sensitive optical elements by ultrafast laser nanostructuring of glass". Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/374905/.
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In this theses I will concentrate on femtosecond laser induced modification in silica glass. One type of modification in fused silica is subwavelength nanogratings. This modification exhibits form birefringence and therefore optical elements can be fabricated based on nanogratings. The main goal of my work was development and fabrication of practical optical elements based on femtosecond laser induced nanogratings. In order to be able to fabricate optical elements, laser induced modification had to be uniform and exhibit strong birefringence. Also fabrication speed has to be high in order to write reasonable size optical element in short time. Optimal fabrication parameters were found by studying physical and optical properties of nanogratings. The first polarization sensitive optical element to be demonstrated was polarization converter, which transforms Gaussian beam with uniform polarization distribution into a cylindrical vector beam. Later on, polarization converters for different types of laser beams and spectral ranges were demonstrated. Properties of generated beams were measured and compared with theoretical modelling. Generated beams were also successfully exploited for material modification and results are compared with theoretical simulations. Same converters can be also used for optical vortices generation. Unique property of such converters is that they allow tuning orbital angular momentum of photons in the light beam and therefore adjusting the torque of the vortex beam. The important feature of this vortex generation technique is that optical angular momentum is changed without affecting intensity distribution of the laser beam. The benefits of tunable optical angular momentum were demonstrated in optical trapping experiment where silica micro spheres were trapped into a rotating ring is performed. The ability to tune the torque of the beam is proved by changing rotation speed change of the beads’ ring. Birefringence can be exploited not only for polarization control but also for phase. Half-wave retarder can induce phase delay to circularly polarized light depending on the azimuth of slow axis of the retarder. Based on that, converter for “diffraction-free” Airy and Bessel beams are fabricated. Properties of generated beams are measured and compared with theoretical simulations. Airy beam converter based on laser induced nanogratings has unique ability to generate dual Airy beam which is superposition two Airy beams accelerating in opposite direction. Generated Airy beam is also used in material modification. Self-detachment of fibre-like structure is observed from laser modified substrate which is speculated to be caused by properties of Airy beam. Finally, an array of micro waveplates is fabricated which together with a linear polarizer and a CCD camera allows real time polarization imaging. Full state of polarization can be measured. For the demonstration, polarization distribution of cylindrical vector beams was measured.
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Fei, Fan. "Risk-sensitive control for a class of non-linear systems and its financial applications". Thesis, University of Liverpool, 2015. http://livrepository.liverpool.ac.uk/2049759/.
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This thesis studies the risk-sensitive control problem for a class of non-linear stochastic systems and its financial applications. The nonlinearity is of the square- root type, and is inspired by applications. The problems of optimal investment and consumption are also considered under several different assumptions on the stochastic interest rate and stochastic volatility. At the beginning, we systematically investigate the nonlinearity of risk-sensitive control problem. It consists of quadratic and square-root terms in the state. Such an optimal control problem can be solved in an explicit closed form by the completion of squares method. As an application of the risk-sensitive control in financial mathematics, the optimal investment problem will be described in the Chapter 4. A new interest rate, which follows the stochastic process with mixed Cox- Ingersoll-Ross (CIR) model and quadratic affine term structure model (QATSM) is introduced. Such an interest rate model admits an explicit price for the zero- coupon bond. In Chapter 5, we consider a portfolio optimization problem on an infinite time horizon. The stochastic interest rate consists not only of the quadratic terms, but also of the square-root terms. On the other hand, the double square root process is also introduced to establish the interest rate model. Under some sufficient conditions, the unique solution of the optimal investment problem is found in an explicit closed form. Furthermore, the optimal consumption problem is considered in Chapter 6 and 7. It can be solved in an explicit closed form via the methods of completion of squares and the change of measure. We provide a detailed discussion on the existence of the optimal trading strategies. Such trading strategies can be deduced for both finite and infinite time horizon cases.
Części książek na temat "SENSITIVE QAC"
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Roy, Rupsa, Swarup Sarkar i Sourav Dhar. "Design and Implementation of an Efficient QCA-Based Multilayer Multi-Bit Parallel Shift Register Using Reversible Level-Sensitive ‘D’ Flip-Flop". W Advances in Communication, Devices and Networking, 57–70. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-2004-2_6.
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Raydugin, Yuri G. "Spin-off Discussions on Project Complexity". W Modern Risk Quantification in Complex Projects, 271–92. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780198844334.003.0018.
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This chapter combines all ‘by-product’ topics that are worth discussing. First, it is argued that complex projects should be adaptive systems. Decentralized short-term flexible planning is encouraged as opposed to centralized detailed scheduling with a primary purpose—to avoid work constraints. Second, a concept of a single failure mode is developed. It is demonstrated that the single failure mode is represented by a two-peak (bi-modal) probabilistic distribution due to existence of a distinctively sensitive risk. Third, a two-well model is drawn from quantum physics to explain a mechanism of the single-mode realization. Fourth, using project system dynamics lessons learned, practical recommendations on organization of project quality assurance (QA) and quality control (QC) are put forward. Fifth, the origin and nature of general uncertainties and internal risk amplifications are uncovered. Sixth, ‘a reverse engineering’ approach to handle risk addressing is contemplated along with a possibility to use stretched targets.
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Ashok Kumar L., Karthika Renuka D. i Shunmugapriya M. C. "Tamil Question Answering System Using Machine Learning". W Deep Learning Research Applications for Natural Language Processing, 167–76. IGI Global, 2022. http://dx.doi.org/10.4018/978-1-6684-6001-6.ch010.
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Tamil question answering system (QAS) is aimed to find relevant answers in in the native language. The system will help farmers to get information in Tamil related to the agriculture domain. Tamil is one of the morphologically rich languages. As a result, developing such systems that process Tamil words is a difficult task. The list of stop words in Tamil has to be collected manually. Parts of speech (POS) tagging is used to identify suitable POS tag for a sequence of Tamil words. The system employs Hidden Markov Model (HMM)-based viterbi algorithm, a machine learning technique for parts of speech tagging of Tamil words. The analyzed question is given to the Google search to obtain relevant documents. On top of Google search, locality sensitive hashing technique (LSH) is utilized to retrieve the five relevant items for the input Tamil question. Jaccard similarity is used to obtain the response from the retrieved document items. The proposed system is modelled using a dataset of 1000 sentences in the agriculture domain.
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Chung, Miri, i Arch G. Woodside. "Causal Recipes Sufficient for Identifying Market Gurus versus Mavens". W Fuzzy Methods for Customer Relationship Management and Marketing, 312–31. IGI Global, 2012. http://dx.doi.org/10.4018/978-1-4666-0095-9.ch014.
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Prior research focusing on the market maven (MM) neglects to consider the possible existence of people who may represent an important source of marketplace information for MMs—the market guru (MG). A “market guru” is a consumer others frequently seek out for advice but who does not seek advice from others. In contrast to MG, a MM is a consumer who other consumers frequently ask for advice and who frequently seeks advice from others. This study raises the proposition that a greater share of MGs versus MMs are innovators, that is, individuals who rely on technical reports to become the first to adopt new products in her or his community. This study applies fuzzy-set qualitative comparative analysis (fs/QCA) to distinguish between MMs and MGs using multi-year data from a national U.S. omnibus survey. The findings support several propositions distinguishing MGs from MMs. MMs evaluate themselves as great influencers of consumers, highly sensitive to normative susceptibility, and possessing superior taste. However, MGs evaluate themselves exactly the opposite from MMs on these conditions.
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Madias, John E. "Management of takotsubo syndrome". W ESC CardioMed, 1305–7. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780198784906.003.0322.
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The pathophysiology of takotsubo syndrome (TTS) is still elusive. Management is non-specific, extrapolated from established treatments for patients with acute coronary syndromes, and heart failure, or other medical or surgical conditions. The mainstay of therapy consists of the use of aspirin, beta blockers, angiotensin-converting enzyme inhibitors/angiotensin receptor blockers (ACEIs/ARBs), diuretics, and anticoagulation. Anticoagulation may be needed not only for evident intracardiac thrombus, but also for severe cardiac wall motion abnormalities. Severe heart failure or cardiogenic shock may necessitate the use of levosimendan, an inotropic agent and a calcium sensitizer, and the implementation of extracorporeal membrane oxygenator, or external cardiac assist devices. Inotropic catecholamines should be used sparingly, particularly in the presence of left ventricular outflow tract obstruction, although their use occasionally becomes inevitable in the presence of severe heart failure or cardiogenic shock. Pericardial tamponade and left ventricular free wall and septal perforations are managed as done routinely. Transcatheter repair has been employed successfully for ventricular septal perforation. Management of atrial fibrillation should follow established principles, and vigilance should be exercised for ventricular arrhythmias, particularly in connection with a prolonged QTc interval. Rarely, for persisting atrioventricular blocks or recurrent ventricular arrhythmias, cardiac electronic implanted devices may be necessary. There are no proven therapies to prevent recurrence of TTS; ACEIs/ARBs, but not beta blockers, have been linked to improved survival at 1-year post discharge. Since TTS is not a benign syndrome, it is hoped that specific management will emerge based on data from controlled randomized clinical trials or large international TTS registries.
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Madias, John E. "Management of takotsubo syndrome". W ESC CardioMed, 1305–7. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780198784906.003.0322_update_001.
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The pathophysiology of takotsubo syndrome (TTS) is still elusive. Management is non-specific, extrapolated from established treatments for patients with acute coronary syndromes, and heart failure, or other medical or surgical conditions. The mainstay of therapy consists of the use of aspirin, beta blockers, angiotensin-converting enzyme inhibitors/angiotensin receptor blockers (ACEIs/ARBs), diuretics, and anticoagulation. Anticoagulation may be needed not only for evident intracardiac thrombus, but also for severe cardiac wall motion abnormalities. Severe heart failure or cardiogenic shock may necessitate the use of levosimendan, an inotropic agent and a calcium sensitizer, and the implementation of extracorporeal membrane oxygenator, or external cardiac assist devices. Inotropic catecholamines should be used sparingly, particularly in the presence of left ventricular outflow tract obstruction, although their use occasionally becomes inevitable in the presence of severe heart failure or cardiogenic shock. Pericardial tamponade and left ventricular free wall and septal perforations are managed as done routinely. Transcatheter repair has been employed successfully for ventricular septal perforation. Management of atrial fibrillation should follow established principles, and vigilance should be exercised for ventricular arrhythmias, particularly in connection with a prolonged QTc interval. Rarely, for persisting atrioventricular blocks or recurrent ventricular arrhythmias, cardiac electronic implanted devices may be necessary. There are no proven therapies to prevent recurrence of TTS; ACEIs/ARBs, but not beta blockers, have been linked to improved survival at 1-year post discharge. Since TTS is not a benign syndrome, it is hoped that specific management will emerge based on data from controlled randomized clinical trials or large international TTS registries.
Streszczenia konferencji na temat "SENSITIVE QAC"
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Bradley, Ashton, Murray Olsen, Simon Haine i Joseph Hope. "Raman schemes for phase sensitive measurement and teleportation of massive particles". W Quantum-Atom Optics Downunder. Washington, D.C.: OSA, 2007. http://dx.doi.org/10.1364/qao.2007.qtud2.
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Richter, T., R. Elschner i C. Schubert. "QAM Phase-Regeneration in a Phase-Sensitive Fiber-Amplifier". W 39th European Conference and Exhibition on Optical Communication (ECOC 2013). Institution of Engineering and Technology, 2013. http://dx.doi.org/10.1049/cp.2013.1436.
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Saemian, Mohammadreza, Djamal Gacemi, Baptiste Chomet, Etienne Rudriguez, Yanko Todorov, Angela Vasanelli, Isabelle Sagnes i in. "Highly Sensitive Room Temperature Heterodyne Detection with Stabilized Qc Lasers". W CLEO: Applications and Technology. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/cleo_at.2022.jw3a.25.
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A heterodyne detection system, made with unipolar devices operating @4.5µm, reaches a record noise equivalent power of 200 fW at room temperature. Key elements of this setup are frequency stabilized QC lasers and high-speed detectors.
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Kjoller, N. K., M. Piels, F. Da Ros, K. Dalgaard, M. Galili i L. K. Oxenlowe. "16-QAM field-quadrature decomposition using polarization-assisted phase sensitive amplification". W 2016 IEEE Photonics Conference (IPC). IEEE, 2016. http://dx.doi.org/10.1109/ipcon.2016.7831206.
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Umeki, T., H. Takenouchi, M. Asobe, Y. Miyamoto i O. Tadanaga. "First demonstration of high-order QAM signal amplification in PPLN-based phase sensitive amplifier". W 39th European Conference and Exhibition on Optical Communication (ECOC 2013). Institution of Engineering and Technology, 2013. http://dx.doi.org/10.1049/cp.2013.1682.
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Olsson, Samuel L. I., Tobias A. Eriksson, Carl Lundström, Magnus Karlsson i Peter A. Andrekson. "Linear and Nonlinear Transmission of 16-QAM Over 105 km Phase-Sensitive Amplified Link". W Optical Fiber Communication Conference. Washington, D.C.: OSA, 2014. http://dx.doi.org/10.1364/ofc.2014.th1h.3.
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Olsson, Samuel L. I., Magnus Karlsson i Peter A. Andrekson. "Long-Haul Optical Transmission of 16-QAM Signal with In-Line Phase-Sensitive Amplifiers". W 2017 European Conference on Optical Communication (ECOC). IEEE, 2017. http://dx.doi.org/10.1109/ecoc.2017.8346223.
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Bogris, A., i D. Syvridis. "All-optical signal processing for 16-QAM using four-level optical phase quantizers based on phase sensitive amplifiers". W 39th European Conference and Exhibition on Optical Communication (ECOC 2013). Institution of Engineering and Technology, 2013. http://dx.doi.org/10.1049/cp.2013.1440.
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Cui, Jiabin, Guo-Wei Lu i Yuefeng Ji. "Optical Vector Quadrature De-multiplexer for m-QAM De-aggregations Based on Orthogonal-polarization-pumped Phase-sensitive Amplifiers". W 2022 Asia Communications and Photonics Conference (ACP). IEEE, 2022. http://dx.doi.org/10.1109/acp55869.2022.10089059.
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Cui, Jiabin, Guo-Wei Lu, Hongxiang Wang, Lin Bai i Yuefeng Ji. "Single-stage Phase-sensitive Amplifier Based Quadrature De-multiplexer for De-aggregating QAM Signals into In-phase and Quadrature Components". W CLEO: Applications and Technology. Washington, D.C.: OSA, 2018. http://dx.doi.org/10.1364/cleo_at.2018.jtu2a.36.
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