1,453 research outputs found

    Dynamical tunneling in molecules: Quantum routes to energy flow

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    Dynamical tunneling, introduced in the molecular context, is more than two decades old and refers to phenomena that are classically forbidden but allowed by quantum mechanics. On the other hand the phenomenon of intramolecular vibrational energy redistribution (IVR) has occupied a central place in the field of chemical physics for a much longer period of time. Although the two phenomena seem to be unrelated several studies indicate that dynamical tunneling, in terms of its mechanism and timescales, can have important implications for IVR. Examples include the observation of local mode doublets, clustering of rotational energy levels, and extremely narrow vibrational features in high resolution molecular spectra. Both the phenomena are strongly influenced by the nature of the underlying classical phase space. This work reviews the current state of understanding of dynamical tunneling from the phase space perspective and the consequences for intramolecular vibrational energy flow in polyatomic molecules.Comment: 37 pages and 23 figures (low resolution); Int. Rev. Phys. Chem. (Review to appear in Oct. 2007

    An unfolding signifier: London's Baltic Exchange in Tallinn

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    In the summer of 2007 an unusual cargo arrived at Muuga and Paldiski harbors outside Tallinn. It consisted of nearly 50 containers holding over 1,000 tons of building material ranging from marble columns, staircases and fireplaces, to sculpted allegorical figures, wooden paneling and old-fashioned telephone booths. They were once part of the Baltic Exchange in the City of London. Soon they will become facets of the landscape of Tallinn. The following article charts this remarkable story and deploys this fragmented monument to analyze three issues relating to the Estonian capital: the relocation of the ‘Bronze Soldier’, the demolition of the Sakala Culture Center, and Tallinn’s future role as European Cultural Capital in 2011

    Insights from Amphioxus into the Evolution of Vertebrate Cartilage

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    Central to the story of vertebrate evolution is the origin of the vertebrate head, a problem difficult to approach using paleontology and comparative morphology due to a lack of unambiguous intermediate forms. Embryologically, much of the vertebrate head is derived from two ectodermal tissues, the neural crest and cranial placodes. Recent work in protochordates suggests the first chordates possessed migratory neural tube cells with some features of neural crest cells. However, it is unclear how and when these cells acquired the ability to form cellular cartilage, a cell type unique to vertebrates. It has been variously proposed that the neural crest acquired chondrogenic ability by recruiting proto-chondrogenic gene programs deployed in the neural tube, pharynx, and notochord. To test these hypotheses we examined the expression of 11 amphioxus orthologs of genes involved in neural crest chondrogenesis. Consistent with cellular cartilage as a vertebrate novelty, we find that no single amphioxus tissue co-expresses all or most of these genes. However, most are variously co-expressed in mesodermal derivatives. Our results suggest that neural crest-derived cartilage evolved by serial cooption of genes which functioned primitively in mesoderm

    Contemporary understanding of riots: classical crowd psychology, ideology and the social identity approach

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    This article explores the origins and ideology of classical crowd psychology, a body of theory reflected in contemporary popularised understandings such as of the 2011 English ‘riots’. This article argues that during the nineteenth century, the crowd came to symbolise a fear of ‘mass society’ and that ‘classical’ crowd psychology was a product of these fears. Classical crowd psychology pathologised, reified and decontextualised the crowd, offering the ruling elites a perceived opportunity to control it. We contend that classical theory misrepresents crowd psychology and survives in contemporary understanding because it is ideological. We conclude by discussing how classical theory has been supplanted in academic contexts by an identity-based crowd psychology that restores the meaning to crowd action, replaces it in its social context and in so doing transforms theoretical understanding of ‘riots’ and the nature of the self

    Spatial capital as a tool for planning practice

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    This purpose of this article is to look at the potential benefit to planning practice of engaging with spatial capital – a concept derived from the social theory of Bourdieu. Doubt is expressed about the theoretical basis for spatial capital; nevertheless, it is argued that it may have merit as a trope for planning practitioners. Spatial capital has a strong empirical basis, making it accessible to planning practice and offering a new means for interpreting and communicating the combined effects of a range of individual urban events such as the gating of communities, differing mobilities and schooling tactics. By focussing on the interplay of social positioning within place, it emphasises the joined-up nature of disadvantage and highlights the limits of environmental determinism. However, its use is not without possible drawbacks. Here, the experience of social capital is informative, as this has been appropriated by groups with quite different readings of its implications for policy

    Concurrent Exposure of Bottlenose Dolphins (Tursiops truncatus) to Multiple Algal Toxins in Sarasota Bay, Florida, USA

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    Sentinel species such as bottlenose dolphins (Tursiops truncatus) can be impacted by large-scale mortality events due to exposure to marine algal toxins. In the Sarasota Bay region (Gulf of Mexico, Florida, USA), the bottlenose dolphin population is frequently exposed to harmful algal blooms (HABs) of Karenia brevis and the neurotoxic brevetoxins (PbTx; BTX) produced by this dinoflagellate. Live dolphins sampled during capture-release health assessments performed in this region tested positive for two HAB toxins; brevetoxin and domoic acid (DA). Over a ten-year study period (2000–2009) we have determined that bottlenose dolphins are exposed to brevetoxin and/or DA on a nearly annual basis (i.e., DA: 2004, 2005, 2006, 2008, 2009; brevetoxin: 2000, 2004, 2005, 2008, 2009) with 36% of all animals testing positive for brevetoxin (n = 118) and 53% positive for DA (n = 83) with several individuals (14%) testing positive for both neurotoxins in at least one tissue/fluid. To date there have been no previously published reports of DA in southwestern Florida marine mammals, however the May 2008 health assessment coincided with a Pseudo-nitzschia pseudodelicatissima bloom that was the likely source of DA observed in seawater and live dolphin samples. Concurrently, both DA and brevetoxin were observed in common prey fish. Although no Pseudo-nitzschia bloom was identified the following year, DA was identified in seawater, fish, sediment, snails, and dolphins. DA concentrations in feces were positively correlated with hematologic parameters including an increase in total white blood cell (p = 0.001) and eosinophil (p<0.001) counts. Our findings demonstrate that dolphins within Sarasota Bay are commonly exposed to two algal toxins, and provide the impetus to further explore the potential long-term impacts on bottlenose dolphin health

    Enhancing access to reports of randomized trials published world-wide – the contribution of EMBASE records to the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library

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    <p>Abstract</p> <p>Background</p> <p>Randomized trials are essential in assessing the effects of healthcare interventions and are a key component in systematic reviews of effectiveness. Searching for reports of randomized trials in databases is problematic due to the absence of appropriate indexing terms until the 1990s and inconsistent application of these indexing terms thereafter.</p> <p>Objectives</p> <p>The objectives of this study are to devise a search strategy for identifying reports of randomized trials in EMBASE which are not already indexed as trials in MEDLINE and to make these reports easily accessible by including them in the Cochrane Central Register of Controlled Trials (CENTRAL) in <it>The Cochrane Library</it>, with the permission of Elsevier, the publishers of EMBASE.</p> <p>Methods</p> <p>A highly sensitive search strategy was designed for EMBASE based on free-text and thesaurus terms which occurred frequently in the titles, abstracts, EMTREE terms (or some combination of these) of reports of trials indexed in EMBASE. This search strategy was run against EMBASE from 1980 to 2005 (1974 to 2005 for four of the terms) and records retrieved by the search, which were not already indexed as randomized trials in MEDLINE, were downloaded from EMBASE, printed and read. An analysis of the language of publication was conducted for the reports of trials published in 2005 (the most recent year completed at the time of this study).</p> <p>Results</p> <p>Twenty-two search terms were used (including nine which were later rejected due to poor cumulative precision). More than a third of a million records were downloaded and scanned and approximately 80,000 reports of trials were identified which were not already indexed as randomized trials in MEDLINE. These are now easily identifiable in CENTRAL, in <it>The Cochrane Library</it>. Cumulative sensitivity ranged from 0.1% to 60% and cumulative precision ranged from 8% to 61%. The truncated term 'random$' identified 60% of the total number of reports of trials but only 35% of the more than 130,000 records retrieved by this term were reports of trials. The language analysis for the sample year 2005 indicated that of the 18,427 reports indexed as randomized trials in MEDLINE, 959 (5%) were in languages other than English. The EMBASE search identified an additional 658 reports in languages other than English, of which the highest number were in Chinese (320).</p> <p>Conclusion</p> <p>The results of the search to date have greatly increased access to reports of trials in EMBASE, especially in some languages other than English. The search strategy used was subjectively derived from a small 'gold standard' set of test records and was not validated in an independent test set. We intend to design an objectively-derived validated search strategy using logistic regression based on the frequency of occurrence of terms in the approximately 80,000 reports of randomized trials identified compared with the frequency of these terms across the entire EMBASE database.</p

    Disease control and functional outcome in three modern combined organ preserving regimens for locally advanced squamous cell carcinoma of the head and neck (SCCHN)

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    <p>Abstract</p> <p>Purpose</p> <p>To report our experience on disease control and functional outcome using three modern combined-modality approaches for definitive radiochemotherapy of locally advanced SCCHN with modern radiotherapy techniques: radiochemotherapy (RChT), radioimmunotherapy (RIT) with cetuximab, or induction chemotherapy with docetaxel, cisplatin, and 5-FU (TPF) combined with either RChT or RIT.</p> <p>Methods</p> <p>Toxicity and outcome was retrospectively analysed in patients receiving definitive RChT, RIT, or induction chemotherapy followed by RChT or RIT between 2006 and 2009. Outcome was estimated using Kaplan-Meier analyses, toxicity was analysed according to CTCAE v 3.0.</p> <p>Results</p> <p>Thirty-eight patients were treated with RChT, 38 patients with RIT, 16 patients received TPF followed by either RChT or RIT. Radiotherapy was mostly applied as IMRT (68%). Long-term toxicity was low, only one case of grad III dysphagia requiring oesophageal dilatation, no case of either xerostomia ≥ grade II or cervical plexopathy were observed. Median overall survival (OS) was 25.7 months (RChT) and 27.7 months (RIT), median locoregional progression-free survival (PFS) was not reached yet. Subgroup analysis showed no significant differences between TPF, RChT, and RIT despite higher age and co-morbidities in the RIT group. Results suggested improved OS, distant and overall PFS for the TPF regimen.</p> <p>Conclusion</p> <p>Late radiation effects in our cohort are rare. No significant differences in outcome between RChT and RIT were observed. Adding TPF suggests improved progression-free and overall survival, impact of TPF on locoregional PFS was marginal, therefore radiotherapeutic options for intensification of local treatment should be explored.</p

    Community-based intervention to promote breast cancer awareness and screening: The Korean experience

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    <p>Abstract</p> <p>Background</p> <p>There are many differences in culture, community identity, community participation, and ownership between communities in Western and Asian countries; thus, it is difficult to adopt the results of community intervention studies from Western countries. In this study, we conducted a multicity, multicomponent community intervention trial to correct breast cancer myths and promote screening mammography for women living in an urban community in Korea.</p> <p>Methods</p> <p>A 6-month, 2-city community intervention trial was conducted. In the intervention city, 480 women were surveyed at baseline and 7 months later to evaluate the effects of the intervention program. Strategies implemented in the intervention city included community outreach and clinic and pharmacy-based in-reach strategies.</p> <p>Results</p> <p>This study showed a 20.4-percentage-point decrease in myths about the link between cancer and breast size, a 19.2-percentage-point decrease in myths concerning mammography costs, and a 14.1-percentage-point increase in intention to undergo screening mammography. We also saw a 23.4-percentage-point increase in the proportion of women at the action stage of the transtheoretical model in the intervention city. In the comparison city, smaller decreases and increases were observed.</p> <p>Conclusions</p> <p>Our study showed the value of an intervention study aimed at reducing belief in breast cancer myths in an urban community in Korea. The invention also made women more likely to undergo mammography in future.</p
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