191 research outputs found

    δ44/40\delta^{44/40}Ca-δ88/86\delta^{88/86}Sr multi-proxy constrains primary origin of Marinoan cap carbonates

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    The Neoproterozoic Earth experienced at least two global-scale glaciations termed Snowball Earth events. 'Cap carbonates' were widely deposited after the events, but controversy surrounds their origin. Here, we apply the novel δ44/40\delta^{44/40}Ca-δ88/86\delta^{88/86}Sr multi-proxy to two Marinoan (ca. 635 Ma) cap carbonate sequences from Namibia and show that the rocks archive primary environmental signals deriving from a combination of seawater-glacial meltwater mixing and kinetic isotope effects. In an outer platform section, dolostone δ44/40\delta^{44/40}Ca and δ88/86\delta^{88/86}Sr values define a line predicted for kinetic mass-dependent isotope fractionation. This dolostone mostly precipitated from meltwater. Moreover, stratigraphically higher samples exhibiting the fastest precipitation rates correlate with elevated 87Sr/86Sr ratios, consistent with long-held expectations that a rapid deglacial weathering pulse forced cap carbonate formation. An inner-platform dolostone shows greater effects from water-mass mixing but still reveals that precipitation rates increased up-section. Overlying limestones show the greatest Ca and Sr contributions from seawater. Amplification of local coastal processes during global ice sheet collapse offers a simple but sufficient proposition to explain the Ca isotope heterogeneity of cap carbonates. Detection of kinetic isotope effects in the rock record provides a basis for developing the δ44/40\delta^{44/40}Ca-δ88/86\delta^{88/86}Sr multi-proxy as an indicator of saturation state and ppCO2_2

    Understanding Terrorist Organizations with a Dynamic Model

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    Terrorist organizations change over time because of processes such as recruitment and training as well as counter-terrorism (CT) measures, but the effects of these processes are typically studied qualitatively and in separation from each other. Seeking a more quantitative and integrated understanding, we constructed a simple dynamic model where equations describe how these processes change an organization's membership. Analysis of the model yields a number of intuitive as well as novel findings. Most importantly it becomes possible to predict whether counter-terrorism measures would be sufficient to defeat the organization. Furthermore, we can prove in general that an organization would collapse if its strength and its pool of foot soldiers decline simultaneously. In contrast, a simultaneous decline in its strength and its pool of leaders is often insufficient and short-termed. These results and other like them demonstrate the great potential of dynamic models for informing terrorism scholarship and counter-terrorism policy making.Comment: To appear as Springer Lecture Notes in Computer Science v2: vectorized 4 figures, fixed two typos, more detailed bibliograph

    National counter-terrorism (C-T) policies and challenges to human rights and civil liberties: Case study of United Kingdom

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    In the UK the rise post-2005 in “home-grown” terrorism, relying to a significant extent on strikes on soft targets by “self-starters,” means that the search for effective preventive measures remains a continuing concern. Below a number of the preventive counter-terror measures adopted post-9/11, and incrementally strengthened in response to the current threat, are found to fall into three categories and represent interventions at the stages in the path toward attacks. This chapter focuses on selected examples of these preventive measures. In terms of three key stages, firstly, there is the attempt to prevent radicalization, under the “Prevent” strategy. A second strategy relies on taking certain measures to control the activities of those considered likely – on the balance of probabilities – to engage in terrorist-related activity. A third preventive strategy relies on the special terrorism offences under the Terrorism Acts 2000 and 2006, as amended, intended to allow for intervention at a very early stage in terrorist plots and in preparing or instigating terrorist acts (“precursor” offences)

    Upper ocean oxygenation dynamics from I/Ca ratios during the Cenomanian-Turonian OAE 2

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    Author Posting. © American Geophysical Union, 2015. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 30 (2015): 510–526, doi:10.1002/2014PA002741.Global warming lowers the solubility of gases in the ocean and drives an enhanced hydrological cycle with increased nutrient loads delivered to the oceans, leading to increases in organic production, the degradation of which causes a further decrease in dissolved oxygen. In extreme cases in the geological past, this trajectory has led to catastrophic marine oxygen depletion during the so-called oceanic anoxic events (OAEs). How the water column oscillated between generally oxic conditions and local/global anoxia remains a challenging question, exacerbated by a lack of sensitive redox proxies, especially for the suboxic window. To address this problem, we use bulk carbonate I/Ca to reconstruct subtle redox changes in the upper ocean water column at seven sites recording the Cretaceous OAE 2. In general, I/Ca ratios were relatively low preceding and during the OAE interval, indicating deep suboxic or anoxic waters exchanging directly with near-surface waters. However, individual sites display a wide range of initial values and excursions in I/Ca through the OAE interval, reflecting the importance of local controls and suggesting a high spatial variability in redox state. Both I/Ca and an Earth System Model suggest that the northeast proto-Atlantic had notably higher oxygen levels in the upper water column than the rest of the North Atlantic, indicating that anoxia was not global during OAE 2 and that important regional differences in redox conditions existed. A lack of correlation with calcium, lithium, and carbon isotope records suggests that neither enhanced global weathering nor carbon burial was a dominant control on the I/Ca proxy during OAE 2.Z.L. thanks NSF OCE 1232620. J.D.O. is supported by an Agouron Postdoctoral Fellowship. T.W.L. acknowledges support from the NSF-EAR and NASA-NAI. A.R. thanks the support of NERC via NE/J01043X/1.2015-11-1

    Identifying potential terrorists: visuality, security and the channel project

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    This article analyses how British counter-radicalization policy in general, and the Channel project in particular, constitute individuals who are vulnerable to radicalization as visible, producing them as subjects of intervention. It thus asks, how can potential terrorists be identified and made knowable? The article first argues that to understand Channel, it is crucial to develop a conceptual account of the security politics of (in)visibilization that draws attention to the ways in which security regimes can, at times, function primarily through the production of regimes of (in)visibility. Using this approach, the article focusses on the role of ‘indicators’ as a technology of (in)visibilization. This role is central to the functioning of Channel, visibilizing certain subjects as threatening. Yet such a production is political. In bringing together a politics of care and a politics of identity, it is a regime of (in)visibility that produces new sites of intervention, contains significant potential consequences for the expression of certain identities, and raises new and troubling possibilities for how contemporary life may be secured

    Redox‐controlled preservation of organic matter during “OAE 3” within the Western Interior Seaway

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    During the Cretaceous, widespread black shale deposition occurred during a series of Oceanic Anoxic Events (OAEs). Multiple processes are known to control the deposition of marine black shales, including changes in primary productivity, organic matter preservation, and dilution. OAEs offer an opportunity to evaluate the relative roles of these forcing factors. The youngest of these events—the Coniacian to Santonian OAE 3—resulted in a prolonged organic carbon burial event in shallow and restricted marine environments including the Western Interior Seaway. New high‐resolution isotope, organic, and trace metal records from the latest Turonian to early Santonian Niobrara Formation are used to characterize the amount and composition of organic matter preserved, as well as the geochemical conditions under which it accumulated. Redox sensitive metals (Mo, Mn, and Re) indicate a gradual drawdown of oxygen leading into the abrupt onset of organic carbon‐rich (up to 8%) deposition. High Hydrogen Indices (HI) and organic carbon to total nitrogen ratios (C:N) demonstrate that the elemental composition of preserved marine organic matter is distinct under different redox conditions. Local changes in δ13C indicate that redox‐controlled early diagenesis can also significantly alter δ13Corg records. These results demonstrate that the development of anoxia is of primary importance in triggering the prolonged carbon burial in the Niobrara Formation. Sea level reconstructions, δ18O results, and Mo/total organic carbon ratios suggest that stratification and enhanced bottom water restriction caused the drawdown of bottom water oxygen. Increased nutrients from benthic regeneration and/or continental runoff may have sustained primary productivity.Key PointsBottom water redox changes triggered carbon burial within the WIS during OAE 3Anoxia developed due to O2 drawdown in a stratified water columnRedox‐controlled changes in OM preservation altered primary δ13Corg signalsPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/112294/1/palo20210.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/112294/2/palo20210-sup-0001-SupportingInfo.pd

    A public health approach to understanding and preventing violent radicalization

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    <p>Abstract</p> <p>Background</p> <p>Very recent acts of terrorism in the UK were perpetrated by 'homegrown', well educated young people, rather than by foreign Islamist groups; consequently, a process of violent radicalization was proposed to explain how ordinary people were recruited and persuaded to sacrifice their lives.</p> <p>Discussion</p> <p>Counterterrorism approaches grounded in the criminal justice system have not prevented violent radicalization. Indeed there is some evidence that these approaches may have encouraged membership of radical groups by not recognizing Muslim communities as allies, citizens, victims of terrorism, and victims of discrimination, but only as suspect communities who were then further alienated. Informed by public health research and practice, a new approach is proposed to target populations vulnerable to recruitment, rather than rely only on research of well known terrorist groups and individual perpetrators of terrorist acts.</p> <p>Conclusions</p> <p>This paper proposes public health research and practice to guard against violent radicalization.</p

    The Influence of Education and Socialization on Radicalization: An Exploration of Theoretical Presumptions and Empirical Research

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    Background and Objective: Research into radicalization does not pay much attention to education. This is remarkable and possibly misses an important influence on the process of radicalization. Therefore this article sets out to explore the relation between education on the one hand and the onset or prevention of radicalization on the other hand. Method: This article is a theoretical literature review. It has analyzed empirical studies-mainly from European countries-about the educational aims, content and style of Muslim parents and parents with (extreme) right-wing sympathies. Results: Research examining similarity in right-wing sympathies between parents and children yields mixed results, but studies among adolescents point to a significant concordance. Research also showed that authoritarian parenting may play a significant role. Similar research among Muslim families was not found. While raising children with distrust and an authoritarian style are prevalent, the impact on adolescents has not been investigated. The empirical literature we reviewed does not give sufficient evidence to conclude that democratic ideal in and an authoritative style of education are conducive to the development of a democratic attitude. Conclusion: There is a knowledge gap with regard to the influence of education on the onset or the prevention of radicalization. Schools and families are underappreciated sources of informal social control and social capital and therefore the gap should be closed. If there is a better understanding of the effect of education, policy as well as interventions can be developed to assist parents and teachers in preventing radicalization. © 2011 The Author(s)
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