317 research outputs found
A classification of data quality assessment and improvement methods
Data quality (DQ) assessment and improvement in larger
information systems would often not be feasible without using suitable “DQ
methods”, which are algorithms that can be automatically executed by
computer systems to detect and/or correct problems in datasets. Currently, these
methods are already essential, and they will be of even greater importance as
the quantity of data in organisational systems grows. This paper provides a
review of existing methods for both DQ assessment and improvement and
classifies them according to the DQ problem and problem context. Six gaps
have been identified in the classification, where no current DQ methods exist,
and these show where new methods are required as a guide for future research
and DQ tool development.This is the accepted manuscript. It's currently embargoed pending publication by Inderscience
Comment on "A centroid molecular dynamics study of liquid para hydrogen and ortho deuterium" [J. Chem. Phys. 121, 6412 (2004)]
We show that the two phase points considered in the recent simulations of liquid para hydrogen by Hone and Voth lie in the liquid-vapor coexistence region of a purely classical molecular dynamics simulation. By contrast, their phase point for ortho deuterium was in the one-phase liquid region for both classical and quantum simulations. These observations are used to account for their report that quantum mechanical effects enhance the diffusion in liquid para hydrogen and decrease it in ortho deuterium
Cleave and Rescue, a novel selfish genetic element and general strategy for gene drive
There is great interest in being able to spread beneficial traits throughout wild populations in ways that are self-sustaining. Here, we describe a chromosomal selfish genetic element, CleaveR [Cleave and Rescue (ClvR)], able to achieve this goal. ClvR comprises two linked chromosomal components. One, germline-expressed Cas9 and guide RNAs (gRNAs)—the Cleaver—cleaves and thereby disrupts endogenous copies of a gene whose product is essential. The other, a recoded version of the essential gene resistant to cleavage and gene conversion with cleaved copies—the Rescue—provides essential gene function. ClvRenhances its transmission, and that of linked genes, by creating conditions in which progeny lacking ClvR die because they have no functional copies of the essential gene. In contrast, those who inherit ClvR survive, resulting in an increase in ClvR frequency. ClvR is predicted to spread to fixation under diverse conditions. To test these predictions, we generated a ClvR element in Drosophila melanogaster. ClvR^(tko) is located on chromosome 3 and uses Cas9 and four gRNAs to disrupt melanogaster technical knockout (tko), an X-linked essential gene. Rescue activity is provided by tko from Drosophila virilis. ClvR^(tko) results in germline and maternal carryover-dependent inactivation of melanogaster tko(>99% per generation); lethality caused by this loss is rescued by the virilis transgene; ClvR^(tko) activities are robust to genetic diversity in strains from five continents; and uncleavable but functional melanogaster tko alleles were not observed. Finally, ClvR^(tko) spreads to transgene fixation. The simplicity of ClvR suggests it may be useful for altering populations in diverse species
Split versions of Cleave and Rescue selfish genetic elements for measured self limiting gene drive
Gene drive elements promote the spread of linked traits, providing methods for changing the composition or fate of wild populations. Drive mechanisms that are self-limiting are attractive because they allow control over the duration and extent of trait spread in time and space, and are reversible through natural selection as drive wanes. Self-sustaining Cleave and Rescue (ClvR) elements include a DNA sequence-modifying enzyme such as Cas9/gRNAs that disrupts endogenous versions of an essential gene, a tightly linked recoded version of the essential gene resistant to cleavage (the Rescue), and a Cargo. ClvR spreads by creating loss-of-function (LOF) conditions in which those without ClvR die because they lack functional copies of the essential gene. We use modeling to show that when the Rescue-Cargo and one or both components required for LOF allele creation (Cas9 and gRNA) reside at different locations (split ClvR), drive of Rescue-Cargo is self-limiting due to a progressive decrease in Cas9 frequency, and thus opportunities for creation of LOF alleles, as spread occurs. Importantly, drive strength and duration can be extended in a measured manner—which is still self-limiting—by moving the two components close enough to each other that they experience some degree of linkage. With linkage, Cas9 transiently experiences drive by hitchhiking with Rescue-Cargo until linkage disequilibrium between the two disappears, a function of recombination frequency and number of generations, creating a novel point of control. We implement split ClvR in Drosophila, with key elements on different chromosomes. Cargo/Rescue/gRNAs spreads to high frequency in a Cas9-dependent manner, while the frequency of Cas9 decreases. These observations show that measured, transient drive, coupled with a loss of future drive potential, can be achieved using the simple toolkit that make up ClvR elements—Cas9 and gRNAs and a Rescue/Cargo
Disponibilidade de documentos: um modelo de avaliação da satisfação da demanda em bibliotecas universitárias
O objetivo deste estudo foi avaliar o desempenhode três bibliotecas universitárias da PUC/RJ na satisfação da demanda expressa por seus usuários;mais especificamente, procurou-se medir a disponibilidade imediata de documentos. Foi utilizado o modelo Nível de Satisfação. Os resultados indicaram que as bibliotecas estudadas são capazes de satisfazer apenas cerca de 50% da demanda. Esse nível de desempenho é semelhante aos encontrados em bibliotecas universitárias de outros países. Concluiu-se que, embora o modelo Nível de Satisfação seja uma medida parcial de avaliação, seu valor emerge de suas características gerais de aplicabilidade.
Descritores
Biblioteca universitária. Nível de satisfação de usuários
Abstract
The purpose of this study was to evaluate the performance of three university libraries in order to satisfy user's expressed needs. A fundamental problem related to users's satisfaction was analyzed namely availability. The model satisfaction level was used. The results showed that the libraries analyzed can only satisfy 50% of the requests.However, these performance levels are similar to those found in university libraries from other more developed countries. Regardless of it's partial character as an evaluation measure, it was concluded that satisfaction level is a model of general applicability
Drivers of Convergence in Eleven Eastern European Countries, Policy Research Working Paper, 6185
This paper investigates the drivers of growth and prosperity in a group of eleven European countries -- Bulgaria, Croatia, the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Poland, Romania, Slovenia, and Slovakia (the EU11). Since the EU11 began the transformation process, this group of emerging countries has made impressive strides as developing market economies and is anchoring development in European Union institutions. There are reasons to believe that the convergence of EU11 income per capita to Western European levels will continue, but will proceed more slowly. The paper concludes that trade and financial integration have sped along at a spectacular pace in the EU11 in the recent past, although trade in modern services and the integration of government bond and equity markets are somewhat behind. As in the rest of Europe, demographic developments will pose huge challenges for the sustainability of public finance in the EU11 economies. In the next several decades, the EU11 labor force is expected to contract more than labor forces in the rest of the European Union, making it even more urgent that countries in the region reform pension systems, change migration policy, and find incentives to attract talent to the region. Closing the gap with the rest of the European Union in educational attainment levels and improving education quality might significantly soften the constraints imposed by the demographic threats and produce sizable returns in terms of additional income convergence
Valor da informação: percepção versus quantificação
Enfoca o uso da informação científica veiculada na literatura primária de uma especialidade sob o prisma da obsolescência. A síndrome objeto-conteúdo-uso, como a condição sine qua non de todas as unidades de literatura, foi o ponto de partida para a distinção conceituai entre a obsolescência do conteúdo (informação) e a do objeto (documento). Argumenta-se que a utilização de indicadores quantitativos baseados apenas no objeto é inadequada à mensuração da validade e utilidade da informação. Este argumento embasa a hipótese de que a obsolescência do objeto é disjunta da obsolescência do conteúdo. O principal objeto da pesquisa foi desenvolver um método para teste da hipótese que é composto de três etapas: mensuração da obsolescência do objeto via análise de citação, mensuração da obsolescência do conteúdo via opinião de especialistas e comparação dos resultados. A hipótese foi testada, em caráter exploratório, na área de Bibliometria. Os principais resultados do teste são os seguintes: a hipótese foi confirmada em nível de percepção teórica do fenômeno e em nível estatístico; foi demonstrado que a validade e utilidade da informação independem da idade do documento onde foi publicada. Em conclusão, foram indicadas áreas para futuras pesquisas metodológicas e conceituais. Enfatiza-se a necessidade premente de enfocara informação como objeto de estudo na área de Ciência da Informação e, ao fazê-lo, incorporara natureza cognitiva da informação.
Palavras-chave
Informação. Estudo bibliométrico. Análise de citação. Obsolescência da informação.
The value of information: its perception versus its quantification
Abstract
Focuses on the use of scientific information disseminated in primary literature. Use is analysed under the specific topic of obsolescence. Object-Content-Use syndrome as the sine qua non condition of all literature itens was the starting point for the conceptual distinction between content (information) and object (document) obsolescence. It is argued that quantitative measures of obsolescence are based merely on object parameters and thus, cannot be used to infer content validity and utility. Accordingly, it is hypothesized that object obsolescence is disjoint of content obsolescence. The main objetive of the study is to develop a methodology for hypothesis testing. The method implies measurement of object obsolescence by means of citation analysis, measurement of content obsolescence by means of expert opinions and comparision of the results. The hypothesis is tested in an exploratory way in the field of Bibliometrics. Main results of the study are: the hypothesis was confirmed at the perceptual and at the inferencial level. It is show that information validity and information utility are not related to document age. In conclusion areas for future conceptual and methodological research are discussed, emphasizing the need to recognize nature of information processing and use.
Keywords
Information. Bibliometrics. Citation analysis. Obsolescence of the informatio
Embedded-Cluster Calculations in a Numeric Atomic Orbital Density-Functional Theory Framework
We integrate the all-electron electronic structure code FHI-aims into the
general ChemShell package for solid-state embedding (QM/MM) calculations. A
major undertaking in this integration is the implementation of pseudopotential
functionality into FHI-aims to describe cations at the QM/MM boundary through
effective core potentials and therewith prevent spurious overpolarization of
the electronic density. Based on numeric atomic orbital basis sets, FHI-aims
offers particularly efficient access to exact exchange and second order
perturbation theory, rendering the established QM/MM setup an ideal tool for
hybrid and double-hybrid level DFT calculations of solid systems. We illustrate
this capability by calculating the reduction potential of Fe in the
Fe-substituted ZSM-5 zeolitic framework and the reaction energy profile for
(photo-)catalytic water oxidation at TiO2(110).Comment: 12 pages, 4 figure
Prior-predictive value from fast growth simulations
Building on a variant of the Jarzynski equation we propose a new method to
numerically determine the prior-predictive value in a Bayesian inference
problem. The method generalizes thermodynamic integration and is not hampered
by equilibration problems. We demonstrate its operation by applying it to two
simple examples and elucidate its performance. In the case of multi-modal
posterior distributions the performance is superior to thermodynamic
integration.Comment: 8 pages, 11 figure
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