87 research outputs found

    Monopoles and Knots in Skyrme Theory

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    We show that the Skyrme theory actually is a theory of monopoles which allows a new type of solitons, the topological knots made of monopole-anti-monopole pair,which is different from the well-known skyrmions. Furthermore, we derive a generalized Skyrme action from the Yang-Mills action of QCD, which we propose to be an effective action of QCD in the infra-red limit. We discuss the physical implications of our results.Comment: 4 pages. Phys. Rev. Lett. in pres

    The double [3+2] photocycloaddition reaction

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    One of a synthetic organic chemists‟ greatest challenges is to create step-efficient routes toward compounds with high molecular complexity. Therefore, reactions such as the meta photocycloaddition of an olefin to a benzene derivative, which provide more than one bond in a single step are of significant importance. It this remarkable reaction three new σ bonds, three new rings and up to six new stereocenters are formed simultaneously. Additional complexity can be added by tethering the two reacting partners together and this form of the reaction has found many uses in natural product synthesis. In this work a remarkable double [3+2] photocycloaddition reaction is reported that results in the formation of a complex cis, cis, cis, trans-[5, 5, 5, 5] fenestrane derivative from a simple flat aromatic acetal with two branching alkenes. During this dramatic transformation four carboncarbon bonds, five new rings and seven new stereocenters are created in a single one-pot process using only UV light. The reaction occurs in a sequential manner from the linear meta photocycloadduct, via a secondary [3+2] addition of the alkene across the cyclopropane of the adduct. In addition, an angular meta photocycloadduct also produced in the initial addition step, undergoes an alternative fragmentation-translocation photoreaction to afford a silphinene-like angular tricyclic compound. In this work the investigation of this newly discovered process is discussed via the synthesis and subsequent irradiation of a series of photosubstrates containing different functional groups in the arene-alkene tether. In addition, attempts toward the synthesis of alternative structures using the same double [3+2] photocycloaddition are reported

    Protease-activated receptor-1 activation by granzyme B causes neurotoxicity that is augmented by interleukin-1 beta

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    This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.This study was funded by the intramural program of the National Institute of Neurological Disorders and Stroke

    The tourism and economic growth enigma: Examining an ambiguous relationship through multiple prisms

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    This paper revisits the ambiguous relationship between tourism and economic growth, providing a comprehensive study of destinations across the globe which takes into account the key dynamics that influence tourism and economic performance. We focus on 113 countries over the period 1995-2014, clustered, for the first time, around six criteria that reflect their economic, political and tourism dimensions. A Panel Vector Autoregressive model is employed which, in contrast to previous studies, allows the data to reveal any tourism-economy interdependencies across these clusters, without imposing a priori the direction of causality. Overall, the economic-driven tourism growth hypothesis seems to prevail in countries which are developing, non-democratic, highly bureaucratic and have low tourism specialization. Conversely, bidirectional relationships are established for economies which are stronger, democratic and with higher levels of government effectiveness. Thus, depending on the economic, political and tourism status of a destination, different policy implications apply

    Further evidence of misclassification of the injury deaths in South Africa: When will the barriers to accurate injury death statistics be removed?

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    Background. Contrary to the World Health Organization’s internationally recommended medical certificate of cause of death, the South African (SA) death notification form (DNF) does not allow for the reporting of the manner of death to permit accurate coding of external causes of injury deaths. Objectives. To describe the injury cause-of-death profile from forensic pathology records collected for the National Cause-of-Death Validation (NCoDV) Project and compare it with profiles from other sources of injury mortality data. In particular, the recording of firearm use in homicides is compared between sources. Methods. The NCoDV Project was a cross-sectional study of deaths that occurred during a fixed period in 2017 and 2018, from a nationally representative sample of 27 health subdistricts in SA. Trained fieldworkers scanned forensic records for all deaths investigated at the forensic mortuaries serving the sampled subdistricts during the study period. Forensic practitioners reviewed the records and completed a medical certificate of cause of death for each decedent. Causes of death were coded to the International Statistical Classification of Diseases, 10th revision (ICD-10), using Iris automated coding software. Cause-specific mortality fractions for injury deaths were compared with Injury Mortality Survey 2017 (IMS 2017) and Statistics South Africa 2017 (Stats SA 2017) datasets. The cause profile for all firearm-related deaths was compared between the three datasets. Results. A total of 5 315 records were available for analysis. Males accounted for 77.6% of cases, and most decedents were aged between 25 and 44 years. Homicide was the leading cause of death (34.7%), followed by transport injuries (32.6%) and suicide (14.7%). This injury cause profile was similar to IMS 2017 but differed markedly from the official statistics, which showed markedly lower proportions of these three causes (15.0%, 11.6% and 0.7%, respectively), and a much higher proportion of other unintentional causes. Investigation of firearm-related deaths revealed that most were homicides in NCoDV 2017/18 (88.5%) and IMS 2017 (93.1%), while in the Stats SA 2017 data, 98.7% of firearm deaths were classified as accidental. Approximately 7% of firearm-related deaths were suicides in NCoDV 2017/18 and IMS 2017, with only 0.3% in Stats SA 2017. Conclusion. The official cause-of-death data for injuries in SA in 2017 differed substantially from findings from the NCoDV 2017/18 study and IMS 2017. Accurate data sources would ensure that public health interventions are designed to reduce the high injury burden. Inclusion of the manner of death on the DNF, as is recommended internationally, is critically important to enable more accurate, reliable and valid reporting of the injury profile

    Environmental Risk Assessment of Fluctuating Diazinon Concentrations in an Urban and Agricultural Catchment Using Toxicokinetic–Toxicodynamic Modeling

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    Temporally resolved environmental risk assessment of fluctuating concentrations of micropollutants is presented. We separated the prediction of toxicity over time from the extrapolation from one to many species and from acute to sublethal effects. A toxicokinetic–toxicodynamic (TKTD) model predicted toxicity caused by fluctuating concentrations of diazinon, measured by time-resolved sampling over 108 days from three locations in a stream network, representing urban, agricultural and mixed land use. We calculated extrapolation factors to quantify variation in toxicity among species and effect types based on available toxicity data, while correcting for different test durations with the TKTD model. Sampling from the distribution of extrapolation factors and prediction of time-resolved toxicity with the TKTD model facilitated subsequent calculation of the risk of undesired toxic events. Approximately one-fifth of aquatic organisms were at risk and fluctuating concentrations were more toxic than their averages. Contribution of urban and agricultural sources of diazinon to the overall risk varied. Thus using fixed concentrations as water quality criteria appears overly simplistic because it ignores the temporal dimension of toxicity. However, the improved prediction of toxicity for fluctuating concentrations may be small compared to uncertainty due to limited diversity of toxicity data to base the extrapolation factors on

    Can cognitive psychological research on reasoning enhance the discussion around moral judgments?

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    In this article we will demonstrate how cognitive psychological research on reasoning and decision making could enhance discussions and theories of moral judgments. In the first part, we will present recent dual-process models of moral judgments and describe selected studies which support these approaches. However, we will also present data that contradict the model predictions, suggesting that approaches to moral judgment might be more complex. In the second part, we will show how cognitive psychological research on reasoning might be helpful in understanding moral judgments. Specifically, we will highlight approaches addressing the interaction between intuition and reflection. Our data suggest that a sequential model of engaging in deliberation might have to be revised. Therefore, we will present an approach based on Signal Detection Theory and on intuitive conflict detection. We predict that individuals arrive at the moral decisions by comparing potential action outcomes (e.g., harm caused and utilitarian gain) simultaneously. The response criterion can be influenced by intuitive processes, such as heuristic moral value processing, or considerations of harm caused

    A Second Best Theory of Institutional Quality

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    This paper illustrates a theory of the second best where the constraints to the achievement of the optimum are of institutional nature. We consider the effects of corruption and bad governance on the public decision to privatize the provision of a service when contracts are incomplete and there is asymmetric information. We show that both corruption and bad governance are detrimental to welfare, but that removing only one of the two is not necessarily beneficial if the other is still present. The theory supplies a possible explanation to the controversial empirical evidence on the economic effects of corruption
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