7,795 research outputs found

    Social Media Exploitation by Covert Networks: A Case Study of ISIS

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    Social media has quickly become a dominant mode of professional and personal communication. Unfortunately, groups who intend to perform illegal and/or harmful activities (such as gangs, criminal groups, and terrorist groups) also use it. These covert networks use social media to foster membership, communicate among followers and non-followers, and obtain ideological and financial support. This exploitation of social media has serious political, cultural, and societal repercussions that go beyond stolen identities, hacked systems, or loss of productivity. There are literal life-and-death consequences of the actions of the groups behind these covert networks. However, through tracking and analyzing social media content, government agencies (in particular those in the intelligence community) can mitigate this threat by uncovering these covert networks, their communication, and their plans. This paper introduces common social media analysis techniques and the current approaches of analyzing covert networks. A case study of the Syrian conflict, with particular attention on ISIS, highlights this exploitation and the process of using social media analysis for intelligence gathering. The results of the case study show that covert networks are resilient and continually adapt their social media use and presence to stay ahead of the intelligence community

    An in vivo biosensor for neurotransmitter release and in situ receptor activity.

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    Tools from molecular biology, combined with in vivo optical imaging techniques, provide new mechanisms for noninvasively observing brain processes. Current approaches primarily probe cell-based variables, such as cytosolic calcium or membrane potential, but not cell-to-cell signaling. We devised cell-based neurotransmitter fluorescent engineered reporters (CNiFERs) to address this challenge and monitor in situ neurotransmitter receptor activation. CNiFERs are cultured cells that are engineered to express a chosen metabotropic receptor, use the G(q) protein-coupled receptor cascade to transform receptor activity into a rise in cytosolic [Ca(2+)] and report [Ca(2+)] with a genetically encoded fluorescent Ca(2+) sensor. The initial realization of CNiFERs detected acetylcholine release via activation of M1 muscarinic receptors. We used chronic implantation of M1-CNiFERs in frontal cortex of the adult rat to elucidate the muscarinic action of the atypical neuroleptics clozapine and olanzapine. We found that these drugs potently inhibited in situ muscarinic receptor activity

    Computational Modeling of Medium Spiny Projection Neurons in Nucleus Accumbens: Toward the Cellular Mechanisms of Afferent Stream Integration

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    The nucleus accumbens (Nacc) regulates the major feedback pathways linking prefrontal cortex, hippocampus, and amygdala. We describe simulations of a biophysical level model of a single medium spiny projection (MSP) neuron, the principle cell of the Nacc. The model suggests that the unusual bistable membrane potential of MSP cells arises from the interplay between two potassium currents, KIR and KA. We find that the transition from the membrane potential down state (~-85mV) to the upstate (~-60mV)requires a significant barrage of synchronized inputs, and that ongoing afferent stimulation is required to maintain the cell in the up state. The Nacc receives the densest dopaminergic innervation in the brain, and the model demonstrates, in agreement with recent experimental evidence, that dopamine acts to increase the energy barrier to membrane potential state transitions. Through its action on KIR and L-type Ca2+ channels, dopamine selectively lowers cell gain in the down state and increases it in the up state, a mechanism for context-dependent gain control. These findings suggest a mechanism of afferent pattern integration in the accumbens arising from transient synchronization among ensembles of MSP neurons. We attempt to relate these findings to possible origins of abnormalities of sensory gating in schizophrenia

    Availability of essential diagnostics in ten low-income and middle-income countries: results from national health facility surveys

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    Background: Pathology and laboratory medicine diagnostics and diagnostic imaging are crucial to achieving universal health coverage. We analysed Service Provision Assessments (SPAs) from ten low-income and middle-income countries to benchmark diagnostic availability. Methods: Diagnostic availabilities were determined for Bangladesh, Haiti, Malawi, Namibia, Nepal, Kenya, Rwanda, Senegal, Tanzania, and Uganda, with multiple timepoints for Haiti, Kenya, Senegal, and Tanzania. A smaller set of diagnostics were included in the analysis for primary care facilities compared with those expected at hospitals, with 16 evaluated in total. Surveys spanned 2004–18, including 8512 surveyed facilities. Country-specific facility types were mapped to basic primary care, advanced primary care, or hospital tiers. We calculated percentages of facilities offering each diagnostic, accounting for facility weights, stratifying by tier, and for some analyses, region. The tier-level estimate of diagnostic availability was defined as the median of all diagnostic-specific availabilities at each tier, and country-level estimates were the median of all diagnostic-specific availabilities of each of the tiers. Associations of country-level diagnostic availability with country income as well as (within-country) region-level availability with region-specific population densities were determined by multivariable linear regression, controlling for appropriate covariates including tier. Findings: Median availability of diagnostics was 19·1% in basic primary care facilities, 49·2% in advanced primary care facilities, and 68·4% in hospitals. Availability varied considerably between diagnostics, ranging from 1·2% (ultrasound) to 76·7% (malaria) in primary care (basic and advanced) and from 6·1% (CT scan) to 91·6% (malaria) in hospitals. Availability also varied between countries, from 14·9% (Bangladesh) to 89·6% (Namibia). Availability correlated positively with log(income) at both primary care tiers but not the hospital tier, and positively with regionspecific population density at the basic primary care tier only. Interpretation: Major gaps in diagnostic availability exist in many low-income and middle-income countries, particularly in primary care facilities. These results can serve as a benchmark to gauge progress towards implementing guidelines such as the WHO Essential Diagnostics List and Priority Medical Devices initiatives

    Afferent Stream Integration in a Model of the Nucleus Accumbens

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    The Nucleus Accumbens (Nacc) receives convergent input from a number of structures including prefrontal cortex, hippocampus, and amygdala, as well as substantial dopaminergic modulation. The principle cell in the Nacc, the medium spiny projection neuron (MSP), has bistable properties that have been proposed as a primary mediator of the integrative properties in the Nacc. In order to determine the minimum biophysical properties required to generate a nonlinear bistable membrane potential, we constructed a 29 compartment MSP cell in GENESIS. This included an inward rectifying K+ (KIR), an A-current K+, HVA Ca2+ and suitable fast Na+ and delayed rectifier K+ channels. Various amounts and distributions of afferent input were examined to determine the amount of coincident input required to move the membrane from the down state (-85 mV) to the up state (-60 mV) and to fire the cell. The number of synchronous afferents required was substantially higher than previously estimated. We modeled the effect of dopaminergic modulation by increasing the conductance of the KIR and Ca2+ channels, demonstrating that the response to input is dependent on state. In parallel studies, in vivo extracellular recordings were obtained from Nacc and neocortex in anesthetized mice. Simultaneous recordings revealed that cortex and Nacc oscillate in synchrony. Lesions that disrupt slow oscillations in the cortex alter rhythmicity in the Nacc, suggesting interdependency of the mechanisms generating bistability

    Universal macroscopic background formation in surface super-roughening

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    We study a class of super-rough growth models whose structure factor satisfies the Family-Vicsek scaling. We demonstrate that a macroscopic background spontaneously develops in the local surface profile, which dominates the scaling of the local surface width and the height-difference. The shape of the macroscopic background takes a form of a finite-order polynomial whose order is decided from the value of the global roughness exponent. Once the macroscopic background is subtracted, the width of the resulting local surface profile satisfies the Family-Vicsek scaling. We show that this feature is universal to all super-rough growth models, and we also discuss the difference between the macroscopic background formation and the pattern formation in other models.Comment: 5 pages, LaTex, 1 figure, minor correction

    Effect of rejection on electrophysiologic function of canine intestinal grafts: Correlation with histopathology and na-k-ATPase activity

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    To investigate whether electrophysiologic changes can detect the early onset and progress of intestinal rejection, changes in in vitro electrophysiologic function, intestinal histopathology, and Na-K-ATPase activity were studied in dogs. Adult mongrel dogs of both sexes, weighing 18-24 kg, were used for auto and allo small bowel transplantation. The entire small bowels, except for short segments at the proximal and distal ends, were snitched between a pair of dogs (allograft). Animals receiving intestinal autotransplantation were used as controls. AIIograji recipients were sacrificed 3, 4, 5, 7, or 9 days after transplantation, and autograft recipients were sacrificed 3, 7, or 14 days afier transplantation. Immunosuppression was not used. Electrophysiologic measurements were done with an Ussing chamber. Histological analysis was performed blindly using whole thickness sections. Na-K-ATPase activity in the mucosal tissue, which is said to regulate the potential difference, was also measured. Potential difference, resistance, and Na-K-ATPase activity of the allografi intestine decreased with time and were significantly lower 7 and 9 days after transplantation compared to host intestine, normul intestine, and graft intestine of controls (autograft). Potential difference, resistance, and Na-K-ATPase activity of the native intestinal tissue and the autografts did not decrease with time. Detection of histologically mild rejection of the intestine, which is important for appropriate immunosup-pressive treatment in clinical cases, could not be achieved based on electrophysiology or Na-K-ATPase activity. Deterioration of electrophysiologic function during rejection correlated with the histological rejection process and Na-K-ATPase activity; however, electrophysiology my not be a reliable tool for monitoring grafrs, since it cannot detect early intestinal rejection. © 1995 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted

    Source Contributions to Carbon Monoxide Concentrations During KORUS‐AQ Based on CAM‐chem Model Applications

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    We investigate regional sources contributing to CO during the Korea United States Air Quality (KORUS-AQ) campaign conducted over Korea (1 May to 10 June 2016) using 17 tagged CO simulations from the Community Atmosphere Model with chemistry (CAM-chem). The simulations use three spatial resolutions, three anthropogenic emission inventories, two meteorological fields, and nine emission scenarios. These simulations are evaluated against measurements from the DC-8 aircraft and Measurements Of Pollution In The Troposphere (MOPITT). Results show that simulations using bottom-up emissions are consistently lower (bias: -34 to -39%) and poorer performing (Taylor skill: 0.38-0.61) than simulations using alternative anthropogenic emissions (bias: -6 to -33%; Taylor skill: 0.48-0.86), particularly for enhanced Asian CO and volatile organic compound (VOC) emission scenarios, suggesting underestimation in modeled CO background and emissions in the region. The ranges of source contributions to modeled CO along DC-8 aircraft from Korea and southern (90 degrees E to 123 degrees E, 20 degrees N to 29 degrees N), middle (90 degrees E to 123 degrees E, 29 degrees N to 38.5 degrees N), and northern (90 degrees E to 131.5 degrees E, 38.5 degrees N to 45 degrees N) East Asia (EA) are 6-13%, similar to 5%, 16-28%, and 9-18%, respectively. CO emissions from middle and northern EA can reach Korea via transport within the boundary layer, whereas those from southern EA are transported to Korea mainly through the free troposphere. Emission contributions from middle EA dominate during continental outflow events (29-51%), while Korean emissions play an overall more important role for ground sites (up to 25-49%) and plumes within the boundary layer (up to 25-44%) in Korea. Finally, comparisons with four other source contribution approaches (FLEXPART 9.1 back trajectory calculations driven by Weather Research and Forecasting (WRF) WRF inert tracer, China signature VOCs, and CO to CO2 enhancement ratios) show general consistency with CAM-chem.National Science Foundation (NSF); U.S. Department of Energy (DOE); National Aeronautics and Space Administration (NASA) Earth Observing System (EOS) Program; NCAR Advanced Study Program Postdoctoral Fellowship; Environment Research and Technology Development Fund of the Ministry of the Environment, Japan [2-1505, 2-1803]; National Science Foundation; NASA [NNX16AD96G, NNX16AE16G, NNX17AG39G]6 month embargo; published online: 1 February 2019This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]
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