916 resultados para retention coefficients
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Mutations in the human phosphofructokinase muscle subunit gene (PFKM) are known to cause myopathy classified as glycogenosis type VII (Tarui disease). Previously described molecular defects include base substitutions altering encoded amino acids or resulting in abnormal splicing. We report a mutation resulting in phosphofructokinase deficiency in three patients from an Ashkenazi Jewish family. Using a reverse transcription PCR assay, PFKM subunit transcripts differing by length were detected in skeletal muscle tissue of all three affected subjects. In the longer transcript, an insertion of 252 nucleotides totally homologous to the structure of the 10th intron of the PFKM gene was found separating exon 10 from exon 11. In addition, two single base transitions were identified by direct sequencing: [exon 6; codon 95; CGA (Arg) to TGA (stop)] and [exon 7; codon 172; ACC (Thr) to ACT (Thr)] in either transcript. Single-stranded conformational polymorphism and restriction enzyme analyses confirmed the presence of these point substitutions in genomic DNA and strongly suggested homozygosity for the pathogenic allele. The nonsense mutation at codon 95 appeared solely responsible for the phenotype in these patients, further expanding genetic heterogeneity of Tarui disease. Transcripts with and without intron 10 arising from identical mutant alleles probably resulted from differential pre-mRNA processing and may represent a novel message from the PFKM gene.
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No presente trabalho foram estudadas as separações de 18 flavonóides (9 agliconas e 9 glicosídeos) pelas técnicas de Cromatografia Líquida de Alta Eficiência em fase reversa (RP-HPLC) e Cromatografia Micelar Eletrocinética em fluxo reverso (RF-Meck). Em ambas as técnicas foram avaliados solventes puros (metanol, acetonitrila e tetrahidrofurano) e suas misturas como formas de promover a variação de seletividade, através da modificação da fase móvel em HPLC, e da natureza do aditivo orgânico em RF-Meck. Nos estudos efetuados em HPLC utilizando-se gradiente, pode-se comprovar a possibilidade da modelagem do fator de retenção em funçã da proporção de solvente utilizados (MeOH, ACN, THF e suas misturas). Pode-se ainda, com base nos dados de retenção e na análise hierárquica de c1usters, diferenciar quatro diferentes grupos de sistemas cromatográficos com diferentes seletividades para flavonóides agliconas, e outros quatro com diferentes seletividades para glicosídeos. Os sistemas cromatográficos mais ortogonais (cada um pertencente a um grupo de seletividade) foram aplicados na separação de uma planta modelo (Azadirachta indica), de onde pode-se escolher a fase móvel mais seletiva para se otimizar a separação dos flavonóides glicosilados presentes nas folhas desta planta. No método final otimizado pode-se identificar e quantificar cinco dos flavonóides majoritários presentes, sendo três glicosídeos de quercetina (rutina, isoquercitrina e quercitrina) e dois glicosídeos de kaempferol (astragalin e nicotiflorin), em amostras de duas diferentes procedências (Piracicaba-SP e Silvânia-GO). Nos estudos envolvendo a separação dos dezoito flavonóides por RFMEKC pode-se comprovar diferenças significativas de seletividade quando se varia a natureza do solvente orgânico utilizado como aditivo, além de se observar tendências na migração em função das propriedades do solvente adicionado e da estrutura molecular do flavonóide. O solvente de menor eficiência para separação dos flavonóides foi o MeOH. Através da análise dos eletroferogramas obtidos através de um planejamento experimental de misturas, e das trocas de pares críticos observadas nos vários eletrólitos utilizados, obteve-se um método de separação com apenas um par crítico em menos de 12 minutos de corrida. O coeficiente de variação obtido para o fator de retenção foi de 1,5% e para área de 3%, considerando-se cinco injeções. O método desenvolvido foi aplicado com sucesso na identificação dos flavonóides majoritários presentes na planta modelo (Neem), obtendo-se o mesmo resultado do estudo anterior. Como forma de avaliar a concentração de flavonóides totais presentes em espécies vegetais é comum a análise de extratos após hidrólise ácida (conversão de todos glicosídeos em agliconas). Desta forma otimizou-se uma metodologia de separação em RP-HPLC de 8 flavonóides agliconas comumente presentes em alimentos e extratos vegetais de uso cosmético. A otimização foi efetuada mediante um planejamento experimental de misturas, para escolha da fase móvel mais seletiva, e de um planejamento fatorial composto central, para otimização das condições de gradiente. O método obtido foi o mais rápido já visto dentro da literatura consultada. A separação em linha de base foi efetuada em menos de 15 minutos, com coeficientes de variação de área entre 0,1 e 1,8%, coeficiente de correlação de 0,9993 a 0,9994 na faixa de 5 a 100 µg/mL, e limites de quantificação estimados na faixa de 0,1 a 0,21µg/mL. O método desenvolvido foi aplicado na otimização das condições de hidrólise de um extrato de Neem. A otimização foi efetuada através de metodologia de superfície de resposta, levando-se em consideração a concentração de ácido adicionada, o tempo de reação, a temperatura, e a concentração de um antioxidante (ácido ascórbico) adicionado. O resultado da otimização foi uma metodologia de hidrólise com tempo de reação igual a 5 minutos, utilizando-se 1,4 mol/L de HCI, 119°C e 500 µg/mL de ácido ascórbico. Através das metodologias de análise e de hidrólise desenvolvidas pode-se constatar a presença e quantificar no extrato de Neem os flavonóides agliconas quercetina, kaempferol e miricetina. Com o objetivo de se avaliar quais os componentes presentes em extratos vegetais são os responsáveis pelo poder antioxidante atribuído a determinadas plantas, foi montado um sistema de avaliação de poder antioxidante \"on-line\" com reação pós-coluna em HPLC (baseado na literatura) utilizando-se como \"radical livre modelo\" o ABTS. A análise da planta modelo (Neem) neste sistema mostrou que os flavonóides glicosilados identificados nas partes anteriores deste trabalho são os responsáveis pelo poder antioxidante atribuído a esta planta. De posse desta informação, e visando a obtenção de extratos para aplicações cosméticas com poder antioxidante, modelou-se a extração dos flavonóide do Neem em função da composição do solvente extrator (água, etanol , propilenoglicol e suas misturas), de acordo com um planejamento simplex centróide ampliado. Além da previsão da concentração dos princípios ativos pode-se ainda prever outras propriedades dos extratos obtidos, tais como, índice de refração e densidade, muitas vezes constituintes de especificações técnicas de acordo com as aplicações a que se destinam (cremes, xampús, etc).
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The intent of the study was to understand the changes that have occurred over the last 25 years in library programs as far as enrollment and diversity of students, number and ethnicity of the faculty, program income and expenses, cost of attendance, and scholarship and fellowship aid, in an effort to better understand library programs granting the MLIS degree. The study also endeavored to identify institutional factors associated with the retention and productivity rates of White students and students of color in schools of library and information science. During the period studied, the proportional representation of White students decreased. For students of color, proportional representation was stable during the same time period. Results revealed a medium effect size of time with productivity rates for both groups declining over time. Retention rate differed significantly by time, with a small effect size with retention rate that initially increased over time, but is now decreasing. The final analyses were meta-regressions to determine if retention and productivity rates can be predicted by cost of attendance, scholarship and fellow aid, and program size. Results indicated that for students of color, program size in 2000 was significantly predictive of retention, cost of attendance was predictive in 2002, and scholarship and fellowship aid was predictive of retention in 2004. No variables were significantly predictive for retention of White students. The last analysis was to determine if productivity rate can be predicted by cost of attendance, scholarship and fellow aid, and program size. Results indicate that for White students in 2002, the cost of attendance was predictive of productivity rating. In 2003, scholarship and fellowship aid was predictive of productivity rate and in 2004, scholarship and fellowship aid was predictive of productivity rating. For students of color, results indicate that only scholarship and fellowship aid in 2005 was predictive of productivity rate. No other variables in any of the years studied showed any significant prediction of productivity rating for students of color.
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The Journal Retention and Needs Listing (JRNL) program: 1) allows libraries to expose lists of print journals for which they have made retention commitments; 2) express needs (or gaps) in their holdings; and 3) communicate offers to fill the gaps in other participating libraries’ holdings. Multiple library consortia and their member libraries use JRNL to facilitate communication between library staff to identify holding commitments, fill gaps, and guide deselection decisions. JRNL is commonly developed and governed by the participating consortia. Currently, those consortia are the Florida Academic Repository (FLARE), the Association of Southeastern Research Libraries (ASERL)/Washington Research Library Consortium (WRLC), and the Western Regional Storage Trust (WEST).
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An economic recession affects the ability of organizations to retain employees. The downturn in the economy causes employers to evaluate how they conduct business causing lay-offs and unemployment rates to rise during periods of recession. A retention strategy is as important as sales and customer service during an economic recession. The impact of decisions made during the recession and the imminent labor shortage will impact the ability of organizations to retain their high performing employees. The author details the areas organizations must consider in a retention strategy and develops a retention model for her employer that can be used to assist with reducing turnover as the economy and the labor force begins to change.
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In the latter half of the twentieth century the workforce dynamic changed when the number of women entering the workforce increased by record amounts. In direct opposition to this change was the inability of organizations to meet the needs of employees with childcare concerns. Organizations and employees alike are best served when policies, procedures, and benefits are implemented to achieve a positive work/life balance. Companies that institute benefits that are supportive to families observe decreases in turnover and increased employee retention. Employees who are offered family friendly resources have been known to stay with companies even when offered a higher salary elsewhere. Demonstrating that retention of valued employees is linked to an organizations ability to offer support for family needs.
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Three sets of laboratory column experimental results concerning the hydrogeochemistry of seawater intrusion have been modelled using two codes: ACUAINTRUSION (Chemical Engineering Department, University of Alicante) and PHREEQC (U.S.G.S.). These reactive models utilise the hydrodynamic parameters determined using the ACUAINTRUSION TRANSPORT software and fit the chloride breakthrough curves perfectly. The ACUAINTRUSION code was improved, and the instabilities were studied relative to the discretisation. The relative square errors were obtained using different combinations of the spatial and temporal steps: the global error for the total experimental data and the partial error for each element. Good simulations for the three experiments were obtained using the ACUAINTRUSION software with slight variations in the selectivity coefficients for both sediments determined in batch experiments with fresh water. The cation exchange parameters included in ACUAINTRUSION are those reported by the Gapon convention with modified exponents for the Ca/Mg exchange. PHREEQC simulations performed using the Gains-Thomas convention were unsatisfactory, with the exchange coefficients from the database of PHREEQC (or range), but those determined with fresh water – natural sediment allowed only an approximation to be obtained. For the treated sediment, the adjusted exchange coefficients were determined to improve the simulation and are vastly different from those from the database of PHREEQC or batch experiment values; however, these values fall in an order similar to the others determined under dynamic conditions. Different cation concentrations were simulated using two different software packages; this disparity could be attributed to the defined selectivity coefficients that affect the gypsum equilibrium. Consequently, different calculated sulphate concentrations are obtained using each type of software; a smaller mismatch was predicted using ACUAINTRUSION. In general, the presented simulations by ACUAINTRUSION and PHREEQC produced similar results, making predictions consistent with the experimental data. However, the simulated results are not identical to the experimental data; sulphate (total S) is overpredicted by both models, most likely due to such factors as the kinetics of gypsum, the possible variations in the exchange coefficients due to salinity and the neglect of other processes.
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Quaternary ammonium-functionalized silica materials were synthesized and applied for solid-phase extraction (SPE) of aromatic amines, which are classified as priority pollutants by US Environmental Protection Agency. Hexamethylenetetramine used for silica surface modification for the first time was employed as SPE sorbent under normal phase conditions. Hexaminium-functionalized silica demonstrated excellent extraction efficiencies for o-toluidine, 4-ethylaniline and quinoline (recoveries 101–107%), while for N,N-dimethylaniline and N-isopropylaniline recoveries were from low to moderate (14–46%). In addition, the suitability of 1-alkyl-3-(propyl-3-sulfonate) imidazolium-functionalized silica as SPE sorbent was tested under normal phase conditions. The recoveries achieved for the five aromatic amines ranged from 89 to 99%. The stability of the sorbent was evaluated during and after 150 extractions. Coefficients of variation between 4.5 and 10.2% proved a high stability of the synthesized sorbent. Elution was carried out using acetonitrile in the case of hexaminium-functionalized silica and water for 1-alkyl-3-(propyl-3-sulfonate) imidazolium-functionalized silica sorbent. After the extraction the analytes were separated and detected by liquid chromatography ultraviolet detection (LC-UV). The retention mechanism of the materials was primarily based on polar hydrogen bonding and π–π interactions. Comparison made with activated silica proved the quaternary ammonium-functionalized materials to offer different selectivity and better extraction efficiencies for aromatic amines. Finally, 1-alkyl-3-(propyl-3-sulfonate) imidazolium-functionalized silica sorbent was successfully tested for the extraction of wastewater and soil samples.
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In this study, the filtration process and the biomass characteristics in a laboratory-scale submerged membrane bioreactor (MBR) equipped with a hollow fiber (HF) microfiltration membrane were studied at different solid retention times (SRT). The MBR was fed by synthetic wastewater and the organic loading rate (OLR) was 0.5, 0.2, 0.1, and 0.08 kg COD kg VSS−1 d−1 for 10, 30, 60, and 90 days of SRT, respectively. The hydraulic retention time was 8.4 h and the permeate flux was 6 L m−2 h−1(LMH). Data analysis confirmed that at all the studied SRTs, the HF-MBR operated very good obtaining of high quality permeates. Chemical Oxygen Demand (COD) removal efficiencies were higher than 95%. The best filtration performance was reached at SRT of 30 d. On the other hand, the respirometric analysis showed that biomass was more active and there was more biomass production at low SRTs. The concentration of soluble extracellular polymeric substances (EPS) decreased with increasing SRT. A decrease of soluble EPS caused a decrease of membrane fouling rate, decreasing the frequency of chemical cleanings. The floc size decreased with SRT increasing. At high SRTs, there was more friction among particles due to the increase of the cellular density and the flocs broke decreasing their size.
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This paper studies stability properties of linear optimization problems with finitely many variables and an arbitrary number of constraints, when only left hand side coefficients can be perturbed. The coefficients of the constraints are assumed to be continuous functions with respect to an index which ranges on certain compact Hausdorff topological space, and these properties are preserved by the admissible perturbations. More in detail, the paper analyzes the continuity properties of the feasible set, the optimal set and the optimal value, as well as the preservation of desirable properties (boundedness, uniqueness) of the feasible and of the optimal sets, under sufficiently small perturbations.
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This paper examines the challenges facing the EU regarding data retention, particularly in the aftermath of the judgment Digital Rights Ireland by the Court of Justice of the European Union (CJEU) of April 2014, which found the Data Retention Directive 2002/58 to be invalid. It first offers a brief historical account of the Data Retention Directive and then moves to a detailed assessment of what the judgment means for determining the lawfulness of data retention from the perspective of the EU Charter of Fundamental Rights: what is wrong with the Data Retention Directive and how would it need to be changed to comply with the right to respect for privacy? The paper also looks at the responses to the judgment from the European institutions and elsewhere, and presents a set of policy suggestions to the European institutions on the way forward. It is argued here that one of the main issues underlying the Digital Rights Ireland judgment has been the role of fundamental rights in the EU legal order, and in particular the extent to which the retention of metadata for law enforcement purposes is consistent with EU citizens’ right to respect for privacy and to data protection. The paper offers three main recommendations to EU policy-makers: first, to give priority to a full and independent evaluation of the value of the data retention directive; second, to assess the judgment’s implications for other large EU information systems and proposals that provide for the mass collection of metadata from innocent persons, in the EU; and third, to adopt without delay the proposal for Directive COM(2012)10 dealing with data protection in the fields of police and judicial cooperation in criminal matters.
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Limited availability of P in soils to crops may be due to deficiency and/or severe P retention. Earlier studies that drew on large soil profile databases have indicated that it is not (yet) feasible to present meaningful values for "plant-available" soil P, obtained according to comparable analytical methods, that may be linked to soil geographical databases derived from 1:5 million scale FAO Digital Soil Map of the World, such as the 5 x 5 arc-minute version of the ISRIC-WISE database. Therefore, an alternative solution for studying possible crop responses to fertilizer-P applied to soils, at a broad scale, was sought. The approach described in this report considers the inherent capacity of soils to retain phosphorus (P retention), in various forms. Main controlling factors of P retention processes, at the broad scale under consideration, are considered to be pH, soil mineralogy, and clay content. First, derived values for these properties were used to rate the inferred capacity for P retention of the component soil units of each map unit (or grid cell) using four classes (i.e., Low, Moderate, High, and Very High). Subsequently, the overall soil phosphorus retention potential was assessed for each mapping unit, taking into account the P-ratings and relative proportion of each component soil unit. Each P retention class has been assigned to a likely fertilizer P recovery fraction, derived from the literature, thereby permitting spatially more detailed, integrated model-based studies of environmental sustainability and agricultural production at the global and continental level (< 1:5 million). Nonetheless, uncertainties remain high; the present analysis provides an approximation of world soil phosphorus retention potential.