4,867 research outputs found

    Attentional load and sensory competition in human vision: Modulation of fMRI responses by load fixation during task-irrelevant stimulation in the peripheral visual field.

    Get PDF
    Perceptual suppression of distractors may depend on both endogenous and exogenous factors, such as attentional load of the current task and sensory competition among simultaneous stimuli, respectively. We used functional magnetic resonance imaging (fMRI) to compare these two types of attentional effects and examine how they may interact in the human brain. We varied the attentional load of a visual monitoring task performed on a rapid stream at central fixation without altering the central stimuli themselves, while measuring the impact on fMRI responses to task-irrelevant peripheral checkerboards presented either unilaterally or bilaterally. Activations in visual cortex for irrelevant peripheral stimulation decreased with increasing attentional load at fixation. This relative decrease was present even in V1, but became larger for successive visual areas through to V4. Decreases in activation for contralateral peripheral checkerboards due to higher central load were more pronounced within retinotopic cortex corresponding to 'inner' peripheral locations relatively near the central targets than for more eccentric 'outer' locations, demonstrating a predominant suppression of nearby surround rather than strict 'tunnel vision' during higher task load at central fixation. Contralateral activations for peripheral stimulation in one hemifield were reduced by competition with concurrent stimulation in the other hemifield only in inferior parietal cortex, not in retinotopic areas of occipital visual cortex. In addition, central attentional load interacted with competition due to bilateral versus unilateral peripheral stimuli specifically in posterior parietal and fusiform regions. These results reveal that task-dependent attentional load, and interhemifield stimulus-competition, can produce distinct influences on the neural responses to peripheral visual stimuli within the human visual system. These distinct mechanisms in selective visual processing may be integrated within posterior parietal areas, rather than earlier occipital cortex

    Cloning transformations in spin networks without external control

    Full text link
    In this paper we present an approach to quantum cloning with unmodulated spin networks. The cloner is realized by a proper design of the network and a choice of the coupling between the qubits. We show that in the case of phase covariant cloner the XY coupling gives the best results. In the 1->2 cloning we find that the value for the fidelity of the optimal cloner is achieved, and values comparable to the optimal ones in the general N->M case can be attained. If a suitable set of network symmetries are satisfied, the output fidelity of the clones does not depend on the specific choice of the graph. We show that spin network cloning is robust against the presence of static imperfections. Moreover, in the presence of noise, it outperforms the conventional approach. In this case the fidelity exceeds the corresponding value obtained by quantum gates even for a very small amount of noise. Furthermore we show how to use this method to clone qutrits and qudits. By means of the Heisenberg coupling it is also possible to implement the universal cloner although in this case the fidelity is 10% off that of the optimal cloner.Comment: 12 pages, 13 figures, published versio

    Water quality in the Wingecarribee Shire, NSW

    Get PDF
    This paper reports on a water quality monitoring program carried out for Wingecarribee Shire Council between March 2002 and July 2004 by University of Wollongong staff and students. Initially 40 sites were sampled on four occasions over three months in a pilot program leading to the selection of sites and parameters for a two year program of monthly monitoring. A range of chemical, physical and biological parameters was measured including nutrients and faecal coliform bacteria on samples collected over the 26 approximately monthly sampling trips. Chlorophyll a, phaeophyton and blue-green algae were also determined over a shorter period. The sampling period included the particularly hot and dry spell September 2002 - January 2003 and a return to less extreme conditions after February 2003. The range of nutrient and coliform data is reported with discussion of the effects of rainfall patterns on nutrients and on faecal coliform counts at the various sites. Small creek sites showed significant changes to nutrient regimes in the long dry spell, whereas the same effect was not apparent in larger river sites. Very wide ranges of faecal coliform counts were found, especially at small creek sites in farmland. Excepting extreme results, generally elevated coliform counts were found when rainfall occurred 0-3 days immediately prior to sampling. Generally lower counts were found in drier weather. The Shire has already implemented some measures to improve water quality in response to this program

    Infectious bronchitis vaccine virus detection and part-S1 genetic variation following single or dual inoculation in broiler chicks.

    Get PDF
    An investigation was undertaken of the extent of genetic variation occurring within infectious bronchitis virus (IBV) vaccine strains following vaccination of day-old broiler chicks. Chicks were divided into seven groups, with two groups receiving single Massachusetts (Mass) vaccinations while the other four were inoculated with combinations of different IBV serotypes; Mass, 793B, D274 and Arkansas (Ark). The remaining group was maintained as an unvaccinated control. Following vaccination, swabs and tissues collected at intervals were pooled and RNA was extracted for detection of IBV by reverse transcription polymerase chain reaction. Positive amplicons were sequenced for the part-S1 gene and compared to the original vaccine strain sequences. Single nucleotide polymorphisms, amino acid variations and hydrophobicity changes were identified and recorded for each sampling point. A total of 106 single nucleotide polymorphisms were detected within 28 isolates. The average single nucleotide polymorphism counts of swab isolates were greater than those found in tissue samples. This translated into 64 amino acid changes; however only six resulted in a change to the hydrophobicity properties. All hydrophobic alterations occurred within swab isolates and the majority were recovered at 3 days post vaccination suggesting such changes to be detrimental to early virus survival. Nucleotide deletions were seen only in the group given the combination of Mass and Ark. Of the 16 sequenced samples in this group, 13 contained the same AAT deletion at position 1033 1035 in the Ark strains. Findings presented in this study demonstrate alteration in the S1 nucleotide sequence following co-administration of live IBV vaccines

    Persistence of Supplemented Bifidobacterium longum subsp. infantis EVC001 in Breastfed Infants.

    Get PDF
    Attempts to alter intestinal dysbiosis via administration of probiotics have consistently shown that colonization with the administered microbes is transient. This study sought to determine whether provision of an initial course of Bifidobacterium longum subsp. infantis (B. infantis) would lead to persistent colonization of the probiotic organism in breastfed infants. Mothers intending to breastfeed were recruited and provided with lactation support. One group of mothers fed B. infantis EVC001 to their infants from day 7 to day 28 of life (n = 34), and the second group did not administer any probiotic (n = 32). Fecal samples were collected during the first 60 postnatal days in both groups. Fecal samples were assessed by 16S rRNA gene sequencing, quantitative PCR, mass spectrometry, and endotoxin measurement. B. infantis-fed infants had significantly higher populations of fecal Bifidobacteriaceae, in particular B. infantis, while EVC001 was fed, and this difference persisted more than 30 days after EVC001 supplementation ceased. Fecal milk oligosaccharides were significantly lower in B. infantis EVC001-fed infants, demonstrating higher consumption of human milk oligosaccharides by B. infantis EVC001. Concentrations of acetate and lactate were significantly higher and fecal pH was significantly lower in infants fed EVC001, demonstrating alterations in intestinal fermentation. Infants colonized by Bifidobacteriaceae at high levels had 4-fold-lower fecal endotoxin levels, consistent with observed lower levels of Gram-negative Proteobacteria and Bacteroidetes. IMPORTANCE The gut microbiome in early life plays an important role for long-term health and is shaped in large part by diet. Probiotics may contribute to improvements in health, but they have not been shown to alter the community composition of the gut microbiome. Here, we found that breastfed infants could be stably colonized at high levels by provision of B. infantis EVC001, with significant changes to the overall microbiome composition persisting more than a month later, whether the infants were born vaginally or by caesarean section. This observation is consistent with previous studies demonstrating the capacity of this subspecies to utilize human milk glycans as a nutrient and underscores the importance of pairing a probiotic organism with a specific substrate. Colonization by B. infantis EVC001 resulted in significant changes to fecal microbiome composition and was associated with improvements in fecal biochemistry. The combination of human milk and an infant-associated Bifidobacterium sp. shows, for the first time, that durable changes to the human gut microbiome are possible and are associated with improved gut function

    Exploring the interdependencies of research funders in the UK

    Get PDF
    Investment in medical research is vital to the continuing improvement of the UK's health and wealth. It is through research that we expand our understanding of disease and develop new treatments for patients. Medical research charities currently contribute over £1 billion annually to medical research in the UK, of which over £350 million is provided by Cancer Research UK. Many charities, including Cancer Research UK, receive no government funding for their research activity. Cancer Research UK is engaged in a programme of work in order to better understand the medical research funding environment and demonstrate the importance of sustained investment. A key part of that is the Office of Health Economics‟ (OHE) 2011 report “Exploring the interdependency between public and charitable medical research”. This study found that there are substantial benefits, both financial and qualitative, from the existence of a variety of funders and that reductions in the level of government financial support for medical research are likely to have broader negative effects. This contributed to other evidence which found that the activities and funding of the charity, public and private sectors respectively are complementary, i.e. mutually reinforcing, rather than duplicative or merely substituting for one another. “Exploring the interdependencies of research funders in the UK” by the Office of Health Economics (OHE) and SPRU: Science and Technology Policy Research at the University of Sussex, represents a continued effort to build the evidence base around the funding of medical research. This report uncovers the extent to which funders of cancer research are interdependent, nationally and internationally. Key figures show that two thirds of publications acknowledging external support have relied on multiple funders, while just under half benefited from overseas funding, and almost a fifth are also supported by industry. In addition the analysis shows that the general public would not want tax funding of cancer research to be reduced, but would not donate enough to charities to compensate for any such reduction

    Hobson’s choice? Constraints on accessing spaces of creative production

    Get PDF
    Successful creative production is often documented to occur in urban areas that are more likely to be diverse, a source of human capital and the site of dense interactions. These accounts chart how, historically, creative industries have clustered in areas where space was once cheap in the city centre fringe and inner city areas, often leading to the development of a creative milieu, and thereby stimulating further creative production. Historical accounts of the development of creative areas demonstrate the crucial role of accessible low-cost business premises. This article reports on the findings of a case study that investigated the location decisions of firms in selected creative industry sectors in Greater Manchester. The study found that, while creative activity remains highly concentrated in the city centre, creative space there is being squeezed and some creative production is decentralizing in order to access cheaper premises. The article argues that the location choices of creative industry firms are being constrained by the extensive city centre regeneration, with the most vulnerable firms, notably the smallest and youngest, facing a Hobson’s choice of being able to access low-cost premises only in the periphery. This disrupts the delicate balance needed to sustain production and begs the broader question as to how the creative economy fits into the existing urban fabric, alongside the competing demands placed on space within a transforming industrial conurbation

    Neptune Trojans and Plutinos: colors, sizes, dynamics, and their possible collisions

    Get PDF
    Neptune Trojans and Plutinos are two subpopulations of trans-Neptunian objects located in the 1:1 and the 3:2 mean motion resonances with Neptune, respectively, and therefore protected from close encounters with the planet. However, the orbits of these two kinds of objects may cross very often, allowing a higher collisional rate between them than with other kinds of trans-Neptunian objects, and a consequent size distribution modification of the two subpopulations. Observational colors and absolute magnitudes of Neptune Trojans and Plutinos show that i) there are no intrinsically bright (large) Plutinos at small inclinations, ii) there is an apparent excess of blue and intrinsically faint (small) Plutinos, and iii) Neptune Trojans possess the same blue colors as Plutinos within the same (estimated) size range do. For the present subpopulations we analyzed the most favorable conditions for close encounters/collisions and address any link there could be between those encounters and the sizes and/or colors of Plutinos and Neptune Trojans. We also performed a simultaneous numerical simulation of the outer Solar System over 1 Gyr for all these bodies in order to estimate their collisional rate. We conclude that orbital overlap between Neptune Trojans and Plutinos is favored for Plutinos with large libration amplitudes, high eccentricities, and small inclinations. Additionally, with the assumption that the collisions can be disruptive creating smaller objects not necessarily with similar colors, the present high concentration of small Plutinos with small inclinations can thus be a consequence of a collisional interaction with Neptune Trojans and such hypothesis should be further analyzed.Comment: 15 pages, 9 figures, 6 tables, accepted for publication in A&

    A Polymorphism in the α4 Nicotinic Receptor Gene (Chrna4) Modulates Enhancement of Nicotinic Receptor Function by Ethanol

    Full text link
    Several studies indicate that ethanol enhances the activity of α4β2 nicotinic acetylcholine receptors (nAChR). Our laboratory has identified a polymorphism in the α4 gene that results in the substitution of an alanine (A) for threonine (T) at amino acid position 529 in the second intracellular loop of the α4 protein. Mouse strains expressing the A variant have, in general, greater nAChR-mediated 86 Rb + efflux in response to nicotine than strains with the T variant. However, the possibility of the polymorphism modulating the effects of ethanol on the 86 Rb + efflux response has not been investigated. Methods : We have used the 86 Rb + efflux method to study the acute effects of ethanol on the function of the α4β2 nAChR in the thalamus in six different mouse strains. Experiments were also performed on tissue samples taken from F2 intercross animals. The F2 animals were derived from A/J mice crossed with a substrain of C57BL/6J mice that carried a null mutation for the gene encoding the β2 nAChR subunit. Results : In strains carrying the A polymorphism (A/J, AKR/J, C3H/Ibg), coapplication of ethanol (10–100 mM) with nicotine (0.03–300 μM) increased maximal ion flux when compared with nicotine alone with no effect on agonist potency. In contrast, ethanol had little effect on the nicotine concentration-response curve in tissue prepared from strains carrying the T polymorphism (Balb/Ibg, C57BL/6J, C58/J). Experiments with the F2 hybrids demonstrated that one copy of the A polymorphism was sufficient to produce a significant enhancement of nAChR function by ethanol (50 mM) in animals that were also β2 +/+. Ethanol had no effect on nicotine concentration-response curves in T/T β2 +/+ animals. Conclusions : The results suggest that the A/T polymorphism influences the initial sensitivity of the α4β2 nAChR to ethanol.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65432/1/01.ALC.0000067973.41153.BC.pd

    Economic Aspects of Sanitation in Developing Countries

    Get PDF
    Improved sanitation has been shown to have great impacts on people's health and economy. However, the progress of achieving the Millennium Development Goals (MDGs) on halving the proportion of people without access to clean water and basic sanitation by 2015 has thus far been delayed. One of the reasons for the slow progress is that policy makers, as well as the general public, have not fully understood the importance of the improved sanitation solutions. This paper, by gathering relevant research findings, aims to report and discuss currently available evidence on the economic aspects of sanitation, including the economic impacts of unimproved sanitation and the costs and economic benefits of some common improved sanitation options in developing countries.; DATA USED IN THIS PAPER WERE OBTAINED FROM DIFFERENT INFORMATION SOURCES: international and national journal articles and reports, web-based statistics, and fact sheets. We used both online search and hand search methods to gather the information.; Scientific evidence has demonstrated that the economic cost associated with poor sanitation is substantial. At the global level, failure to meet the MDG water and sanitation target would have ramifications in the area of US38billion,andsanitationaccountsfor9238 billion, and sanitation accounts for 92% of this amount. In developing countries, the spending required to provide new coverage to meet the MDG sanitation target (not including program costs) is US142 billion (USyear2005).ThistranslatestoapercapitaspendingofUS year 2005). This translates to a per capita spending of US28 for sanitation. Annually, this translates to roughly US14million.Theevidencecompliedinthispaperdemonstratesthatinvestinginsanitationissociallyandeconomicallyworthwhile.ForeveryUS14 million. The evidence complied in this paper demonstrates that investing in sanitation is socially and economically worthwhile. For every US1 invested, achieving the sanitation MDG target and universal sanitation access in the non-OECD countries would result in a global return of US9.1andUS9.1 and US11.2, respectively.; Given the current state of knowledge, sanitation is undeniably a profitable investment. It is clear that achieving the MDG sanitation target not only saves lives but also provides a foundation for economic growth
    corecore