638 research outputs found
Privileging information is inevitable
Libraries, archives and museums have long collected physical materials and other artefacts. In so doing they have established formal or informal policies defining what they will (and will not) collect. We argue that these activities by their very nature privilege some information over others and that the appraisal that underlies this privileging is itself socially constructed. We do not cast this in a post-modernist or negative light, but regard a clear understanding of it as fact and its consequences as crucial to understanding what collections are and what the implications are for the digital world. We will argue that in the digital world it is much easier for users to
construct their own collections from a combination of resources, some privileged and curated by information professionals and some privileged by criteria that include
the frequency with which other people link to and access them. We conclude that developing these ideas is an important part of placing the concept of a digital or
hybrid paper/digital library on a firm foundation and that information professionals need to learn from each other, adopting elements of a variety of different approaches
to describing and exposing information. A failure to do this will serve to push information professional towards the margins of the information seekers perspective
The L^2 geometry of spaces of harmonic maps S^2 -> S^2 and RP^2 -> RP^2
Harmonic maps from S^2 to S^2 are all weakly conformal, and so are
represented by rational maps. This paper presents a study of the L^2 metric
gamma on M_n, the space of degree n harmonic maps S^2 -> S^2, or equivalently,
the space of rational maps of degree n. It is proved that gamma is Kaehler with
respect to a certain natural complex structure on M_n. The case n=1 is
considered in detail: explicit formulae for gamma and its holomorphic
sectional, Ricci and scalar curvatures are obtained, it is shown that the space
has finite volume and diameter and codimension 2 boundary at infinity, and a
certain class of Hamiltonian flows on M_1 is analyzed. It is proved that
\tilde{M}_n, the space of absolute degree n (an odd positive integer) harmonic
maps RP^2 -> RP^2, is a totally geodesic Lagrangian submanifold of M_n, and
that for all n>1, \tilde{M}_n is geodesically incomplete. Possible
generalizations and the relevance of these results to theoretical physics are
briefly discussed.Comment: 27 pages, 2 figure
Vaccinia Virus Serpin-1 Deletion Mutant Exhibits a Host Range Defect Characterized by Low Levels of Intermediate and Late mRNAs
AbstractOrthopoxviruses encode three serpin homologsâSPI-1, SPI-2 and SPI-3âof which SPI-2 has been well characterized as an inhibitor of ICE-like proteases. A rabbitpox virus SPI-1 deletion mutant exhibited a host range restriction in human lung A549 and pig kidney 15 cell lines that was attributed to apoptosis. Here we report that replication of a vaccinia virus SPI-1 deletion mutant (ÎSPI-1) was restricted in primary human keratinocytes as well as A549 cells. Although chromatin condensation was detected in some A549 cells, other morphological or biochemical signs of apoptosis including DNA fragmentation, cleavage of poly(ADP-ribose)polymerase or nuclear mitotic apparatus protein, or caspase 3 activation were not found. Moreover, ÎSPI-1 protected A549 cells from apoptosis induced by tumor necrosis factor, whereas the corresponding ÎSPI-2 mutant did not. Further studies indicated undiminished amounts of vaccinia virus early mRNA and replicated DNA in the absence of the SPI-1 product. However, there were reduced amounts of viral intermediate and late mRNAs, viral late proteins, cleaved core proteins, and virus particles. These data suggested that apoptosis is not the determining factor in the host range restriction of ÎSPI-1 and that the SPI-1 gene product is needed to allow efficient expression of intermediate and late genes in A549 cells
Landowner willingness to engage in long-term timber leases in West Virginia, USA
As global competition increases for wood-based products, the need for more efficient supply chains becomes increasingly important. In the forest products sector, these supply chains involve individuals and firms ranging from private forestland owners with standing timber to factories producing final finished products. Under the assumption that âtransparentâ supply chains are beneficial to members within the supply chain, the authors are investigating how this transparency can be increased and what benefits might accrue to private forest owners who are associated with a specific supply chain under a long-term agreement. In recent years, hunting lease agreements between family forest owners and various organized hunt clubs or individuals have become commonplace in the Appalachian mountains of West Virginia. Can long-term timber leases become a new opportunity for landowners, forestry professionals, and wood-based industries? This paper describes a survey of private forestland owners in West Virginia that investigated the perceived concerns, benefits and barriers landowners have with regard to entering long-term timber leases with forestry professionals and timber firms
PAR-3 defines a central subdomain of the cortical actin cap in mouse eggs
AbstractThe evolutionarily conserved partitioning defective (PAR) protein PAR-3 is pivotal for establishing and maintaining cell polarity. During mammalian oocyte maturation, the radially symmetric oocyte is transformed into a highly polarized metaphase II (MII)-arrested egg. We therefore examined several aspects of PAR-3 expression during oocyte maturation. We cloned two novel PAR-3 transcripts from an oocyte library that likely encode proteins of Mr = 73 K and 133 K that are phosphorylated during maturation. PAR-3, which is found throughout the GV-intact oocyte, becomes asymmetrically localized during meiosis. Following germinal vesicle breakdown, PAR-3 surrounds the condensing chromosomes and associates with the meiotic spindles. Prior to emission of the first and second polar bodies, PAR-3 is located within a central subdomain of the polarized actin cap, which overlies the spindle. This cortical PAR-3 localization depends on intact microfilaments. These results suggest a role for PAR-3 in establishing asymmetry in the egg and in defining the future site of polar body emission
Using J-K-fold Cross Validation to Reduce Variance When Tuning NLP Models
K-fold cross validation (CV) is a popular method for estimating the true performance of machine learning models, allowing model selection and parameter tuning. However, the very process of CV requires random partitioning of the data and so our performance estimates are in fact stochastic, with variability that can be substantial for natural language processing tasks. We demonstrate that these unstable estimates cannot be relied upon for effective parameter tuning. The resulting tuned parameters are highly sensitive to how our data is partitioned, meaning that we often select sub-optimal parameter choices and have serious reproducibility issues. Instead, we propose to use the less variable J-K-fold CV, in which J independent K-fold cross validations are used to assess performance. Our main contributions are extending J-K-fold CV from performance estimation to parameter tuning and investigating how to choose J and K. We argue that variability is more important than bias for effective tuning and so advocate lower choices of K than are typically seen in the NLP literature, instead use the saved computation to increase J. To demonstrate the generality of our recommendations we investigate a wide range of case-studies: sentiment classification (both general and target-specific), part-of-speech tagging and document classification
Wineries and wine quality: The influence of location and archetype in the Hunter Valley region in Australia
Geographical concentrations of wineries often occur within a region for obvious reasons of terroir. However, localised spatial concentrations of wineries may exist because of other factors. This paper explores whether co-location exists among wineries that have higher wine ratings in the Hunter Valley wine region in New South Wales, Australia. Key conclusions are that clustering of Hunter Valley wineries producing high-quality wines does not exist, the quality rating of a winery is influenced by its terroir, and wine quality among wineries in the region is higher for those producing the territorial brand wine of Semillon. Blending was found to have no impact on the quality of wine produced by a winery
The impact of target frequency on intra-individual variability in euthymic bipolar disorder: a comparison of two sustained attention tasks.
Greater intra-individual variability (IIV) in reaction time (RT) on a sustained attention task has been reported in patients with bipolar disorder (BD) compared with healthy controls. However, it is unclear whether IIV is task specific, or whether it represents general crosstask impairment in BD. This study aimed to investigate whether IIV occurs in sustained attention tasks with different parameters. Twenty-two patients with BD (currently euthymic) and 17 controls completed two sustained attention tasks on different occasions: a low target frequency (~20%) Vigil continuous performance test (CPT) and a high target frequency (~70%) CPT version A-X (CPT-AX). Variability measures (individual standard deviation and coefficient of variation) were calculated per participant, and ex-Gaussian modeling was also applied. This was supplemented by Vincentile analysis to characterize RT distributions. Results indicated that participants (patients and controls) were generally slower and more variable when completing the Vigil CPT compared with CPT-AX. Significant group differences were also observed in the Vigil CPT, with euthymic BD patients being more variable than controls. This result suggests that IIV in BD demonstrates some degree of task specificity. Further research should incorporate analysis of additional RT distributional models (drift diffusion and fast Fourier transform) to fully characterize the pattern of IIV in BD, as well as its relationship to cognitive processes
The multidimensional causal factors of âwet litterâ in chicken-meat production
The problem of âwet litterâ, which occurs primarily in grow-out sheds for meat chickens (broilers), has been recognised for nearly a century. Nevertheless, it is an increasingly important problem in contemporary chicken-meat production as wet litter and associated conditions, especially footpad dermatitis, have developed into tangible welfare issues. This is only compounded by the market demand for chicken paws and compromised bird performance. This review considers the multidimensional causal factors of wet litter. While many causal factors can be listed it is evident that the critical ones could be described as micro-environmental factors and chief amongst them is proper management of drinking systems and adequate shed ventilation. Thus, this review focuses on these environmental factors and pays less attention to issues stemming from health and nutrition. Clearly, there are times when related avian health issues of coccidiosis and necrotic enteritis cannot be overlooked and the development of efficacious vaccines for the latter disease would be advantageous. Presently, the inclusion of phytate-degrading enzymes in meat chicken diets is routine and, therefore, the implication that exogenous phytases may contribute to wet litter is given consideration. Opinion is somewhat divided as how best to counter the problem of wet litter as some see education and extension as being more beneficial than furthering research efforts. However, it may prove instructive to assess the practice of whole grain feeding in relation to litter quality and the incidence of footpad dermatitis. Additional research could investigate the relationships between dietary concentrations of key minerals and the application of exogenous enzymes with litter quality
The impact of surgical site infection on hospitalisation, treatment costs, and health-related quality of life after vascular surgery
Surgical site infections (SSI) substantially increase costs for healthcare providers because of additional treatments and extended patient recovery. The objective of this study was to assess the cost and healthârelated quality of life impact of SSI, from the perspective of a large teaching hospital in England. Data were available for 144 participants undergoing clean or cleanâcontaminated vascular surgery. SSI development, length of hospital stay, readmission, and antibiotic use were recorded over a 30âday period. Patientâreported EQâ5D scores were obtained at baseline, day 7 and day 30. Linear regressions were used to control for confounding variables. A mean SSIâassociated length of stay of 9.72âdays resulted in an additional cost of ÂŁ3776 per patient (including a mean antibiotic cost of ÂŁ532). Adjusting for age, smoking status, and procedure type, SSI was associated with a 92% increase in length of stay (P < 0.001). The adjusted episode cost was ÂŁ3040. SSI reduced patient utility between baseline and day 30 by 0.156 (P =â0.236). Readmission rates were higher with SSI (P =â0.017), and the rate to return to work within 90âdays was lower. Therefore, strategies to reduce the risk of surgical site infection for highârisk vascular patients should be investigated
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