A Two-Population Insurgency in Colombia: Quasi-Predator-Prey Models - A Trend Towards Simplicity

A sequence of analytic mathematical models has been developed in the context of the low-level insurgency in Colombia, from 1993 to the present. They are based on generalizations of the two-population predator-prey model commonly applied in ecological modeling, and interestingly, the less sophisticated models yield more insight into the problem than the more complicated ones, but the formalism is available to adapt the model upwards in the event that more data becomes available, or as the situation increases in complexity. Specifically, so-called forcing terms were included initially in the coupled differential equations to represent the effects of government policies towards both the narco-terrorist or insurgent (I) and susceptible (S) populations. These terms are in general functions of time, since it is to be expected that changes in policy will occur as the outcomes of previously implemented policies are recognized. Both continuous and discontinuous forcing functions can be appropriate for each population. Although nonhomogeneous systems are discussed for both populations, the majority of the analysis focused on a system with forcing terms for the terrorist population only. Two categories of models emerged: 1-in which the time-dependent forcing terms were independent of the two populations, and 2-in which these terms were directly proportional to the respective populations. Model 2 in fact, can be considered as a generalization of the unforced (or homogeneous) version of model 1, and as such is implemented to describe the data obtained for the insurgent population from 1993-2003. This provides some restrictions on the unknown parameters in the model. Because of new government policy towards the insurgent population as a result of the election of President Uribe in 2002, a slight but significant modification of this model is used to describe the I-population from 2003 to the present time, again resulting in useful relationships between the various model parameters. The data suggest that a further simplification in this model is appropriate beyond 2003, and an analytic solution was found for both populations. A further simplification results from examining the related decoupled system of equations, yielding a straightforward predictive model for the behavior of the S-population in particular. Finally, in the Appendix, detailed analysis of model 2 yields a general analytic solution of the system for a wide range of sub-models, expressible in terms of confluent hypergeometric functions. (C) 2008 Elsevier Ltd. All rights reserved

The Geometric Growth of M&S Education: Pushing Forward, Pushing Outward

M&S education is experiencing a geometric growth that is placing it front and center as a discipline and as an interdisciplinary tool. This article discusses the evolution of the discipline of M&S. It answers: Why has M&S education experienced a forward and outward growth? What is it that makes this discipline unique? What is the current state of M&S education

A Physiological Role for Amyloid Beta Protein: Enhancement of Learning and Memory

Amyloid beta protein (A[beta]) is well recognized as having a significant role in the pathogenesis of Alzheimer's disease (AD). The reason for the presence of A[beta] and its physiological role in non-disease states is not clear. In these studies, low doses of A[beta] enhanced memory retention in two memory tasks and enhanced acetylcholine production in the hippocampus _in vivo_. We then tested whether endogenous A[beta] has a role in learning and memory in young, cognitively intact mice by blocking endogenous A[beta] in healthy 2-month-old CD-1 mice. Blocking A[beta] with antibody to A[beta] or DFFVG (which blocks A[beta] binding) or decreasing A[beta] expression with an antisense directed at the A[beta] precursor APP all resulted in impaired learning in T-maze foot-shock avoidance. Finally, A[beta]1-42 facilitated induction and maintenance of long term potentiation in hippocampal slices, whereas antibodies to A[beta] inhibited hippocampal LTP. These results indicate that in normal healthy young animals the presence of A[beta] is important for learning and memory

Model validation for a noninvasive arterial stenosis detection problem

Copyright @ 2013 American Institute of Mathematical SciencesA current thrust in medical research is the development of a non-invasive method for detection, localization, and characterization of an arterial stenosis (a blockage or partial blockage in an artery). A method has been proposed to detect shear waves in the chest cavity which have been generated by disturbances in the blood flow resulting from a stenosis. In order to develop this methodology further, we use both one-dimensional pressure and shear wave experimental data from novel acoustic phantoms to validate corresponding viscoelastic mathematical models, which were developed in a concept paper [8] and refined herein. We estimate model parameters which give a good fit (in a sense to be precisely defined) to the experimental data, and use asymptotic error theory to provide confidence intervals for parameter estimates. Finally, since a robust error model is necessary for accurate parameter estimates and confidence analysis, we include a comparison of absolute and relative models for measurement error.The National Institute of Allergy and Infectious Diseases, the Air Force Office of Scientific Research, the Deopartment of Education and the Engineering and Physical Sciences Research Council (EPSRC)

Interfacial Electrical Properties of Ion-Beam Sputter Deposited Amorphous Carbon on Silicon

Amorphous, “diamond-like” Carbon films have been deposited on Si substrates, using ion-beam sputtering. The interfacial properties are studied using capacitance and conductance measurements. Data are analyzed using existing theories for interfacial electrical properties. The density of electronic states at the interface, along with corresponding time constants are determined, and the density of interface states is unusually low for an as yet unoptimize

Women can bear a bigger burden: ante- and post-mortem evidence for reserve in the face of tau.

In this study, we aimed to assess whether women are able to withstand more tau before exhibiting verbal memory impairment. Using data from 121 amyloid-β-positive Alzheimer's Disease Neuroimaging Initiative participants, we fit a linear model with Rey Auditory Verbal Learning Test score as the response variable and tau-PET standard uptake value ratio as the predictor and took the residuals as an estimate of verbal memory reserve for each subject. Women demonstrated higher reserve (i.e. residuals), whether the Learning (t = 2.78, P = 0.006) or Delay (t = 2.14, P = 0.03) score from the Rey Auditory Verbal Learning Test was used as a measure of verbal memory ability. To validate these findings, we examined 662 National Alzheimer's Coordinating Center participants with a C2/C3 score (Consortium to Establish a Registry for Alzheimer's Disease) at autopsy. We stratified our National Alzheimer's Coordinating Center sample into Braak 1/2, Braak 3/4 and Braak 5/6 subgroups. Within each subgroup, we compared Logical Memory scores between men and women. Men had worse verbal memory scores within the Braak 1/2 (Logical Memory Immediate: β = -5.960 ± 1.517, P < 0.001, Logical Memory Delay: β = -5.703 ± 1.677, P = 0.002) and Braak 3/4 (Logical Memory Immediate: β = -2.900 ± 0.938, P = 0.002, Logical Memory Delay: β = -2.672 ± 0.955, P = 0.006) subgroups. There were no sex differences in Logical Memory performance within the Braak 5/6 subgroup (Logical Memory Immediate: β = -0.314 ± 0.328, P = 0.34, Logical Memory Delay: β = -0.195 ± 0.287, P = 0.50). Taken together, our results point to a sex-related verbal memory reserve

Tau and atrophy: domain-specific relationships with cognition.

BackgroundLate-onset Alzheimer's disease (AD) is characterized by primary memory impairment, which then progresses towards severe deficits across cognitive domains. Here, we report how performance in cognitive domains relates to patterns of tau deposition and cortical thickness.MethodsWe analyzed data from 131 amyloid-β positive participants (55 cognitively normal, 46 mild cognitive impairment, 30 AD) of the Alzheimer's Disease Neuroimaging Initiative who underwent magnetic resonance imaging (MRI), flortaucipir (FTP) positron emission tomography, and neuropsychological testing. Surface-based vertex-wise and region-of-interest analyses were conducted between FTP and cognitive test scores, and between cortical thickness and cognitive test scores.ResultsFTP and thickness were differentially related to cognitive performance in several domains. FTP-cognition associations were more widespread than thickness-cognition associations. Further, FTP-cognition patterns reflected cortical systems that underlie different aspects of cognition.ConclusionsOur findings indicate that AD-related decline in domain-specific cognitive performance reflects underlying progression of tau and atrophy into associated brain circuits. They also suggest that tau-PET may have better sensitivity to this decline than MRI-derived measures of cortical thickness

Probing F-theory With Multiple Branes

We study multiple 3-branes on an F theory orientifold. The world-volume theory of the 3-branes is d=4, N=2 Sp(2k) gauge theory with an antisymmetric tensor and four flavors of matter in the fundamental. The solution of this gauge theory is found for vanishing bare mass of the antisymmetric tensor matter, and massive fundamental matter. The integrable system underlying this theory is constructed.Comment: 9 pages, harvma

Brief of Amici Curiae Public Justice, the Prisoners’ Rights Project of the Legal Aid Society of the City of New York, and the Pennsylvania Institutional Law Project in Support of Plaintiffs-Appellees (Argueta v. United States Immigration and Customs Enforcement)

Public Justice is a national public interest law firm dedicated to preserving access to justice, remedying government and corporate wrongdoing, and holding the powerful accountable in courts. As part of its access-to-justice work, Public Justice created an Iqbal Project in 2009 to combat misuse of the Supreme Court’s decision in Ashcroft v. Iqbal, 129 S. Ct. 1937 (2009). The Project tracks developments in the case law and provides assistance to counsel facing Iqbal-based motions. Public Justice is concerned that overbroad readings of Iqbal threaten to deny justice to many injured plaintiffs with meritorious claims. In addition to Public Justice’s Iqbal-related interest in this case, the firm also represents prisoners, arrestees, other detainees, their family members, and other plaintiffs in a variety of cases involving constitutional claims. See, e.g., Hui v. Castaneda, 130 S. Ct. 1845 (2010); Dillon v. Rogers, 596 F.3d 260 (5th Cir. 2010); Menotti v. City of Seattle, 409 F.3d 1113 (9th Cir. 2005); Everett v. Cherry, No. 08-00622 (E.D. Va.) (case pending). Public Justice is concerned that Appellants’ arguments regarding supervisory liability will, if accepted, prevent many plaintiffs with constitutional claims from obtaining a full remedy. The Legal Aid Society of the City of New York is a private organization that has provided free legal assistance to indigent persons in New York City for over 125 years. Through its Prisoners’ Rights Project, the Society seeks to ensure that 2 prisoners’ constitutional and statutory rights are protected. The Society advocates on behalf of prisoners in the New York City jails and New York state prisons, and conducts litigation on prison conditions. The Society often litigates claims of supervisory liability. The Pennsylvania Institutional Law Project is a private not-for-profit organization created to ensure equal access to justice for indigent institutionalized persons. Part of the Pennsylvania Legal Aid Network, the Institutional Law Project provides direct representation services, self-help and other legal materials, and class representation to eligible low-income residents of Pennsylvania’s prisons, jails, state hospitals, and state centers. The Project also takes part in advocacy and legislative initiatives concerning institutional reform in Pennsylvania

Short sleep duration is associated with risk of future diabetes but not cardiovascular disease: a prospective study and meta-analysis

Epidemiologic studies have observed association between short sleep duration and both cardiovascular disease (CVD) and type 2 diabetes, although these results may reflect confounding by pre-existing illness. This study aimed to determine whether short sleep duration predicts future CVD or type 2 diabetes after accounting for baseline health. Baseline data for 241,949 adults were collected through the 45 and Up Study, an Australian prospective cohort study, with health outcomes identified via electronic database linkage. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals. Compared to 7h sleep, <6h sleep was associated with incident CVD in participants reporting ill-health at baseline (HR=1.38 [95% CI: 1.12-1.70]), but not after excluding those with baseline illness and adjusting for baseline health status (1.03 [0.88-1.21]). In contrast, the risk of incident type 2 diabetes was significantly increased in those with <6h versus 7h sleep, even after excluding those with baseline illness and adjusting for baseline health (HR=1.29 [1.08-1.53], P=0.004). This suggests the association is valid and does not simply reflect confounding or reverse causation. Meta-analysis of ten prospective studies including 447,124 participants also confirmed an association between short sleep and incident diabetes (1.33 [1.20-1.48]). Obtaining less than 6 hours of sleep each night (compared to 7 hours) may increase type 2 diabetes risk by approximately 30%.The Sax Institute; Cancer Council New South Wales; the National Heart Foundation of Australia (New South Wales Division); The New South Wales Ministry of Health; Beyondblue: the National Depression Initiative; Ageing, Disability and Home Care, New South Wales Family and Community Services; the Australian Red Cross Blood Service; Uniting Care Ageing; the Australian National Health and Medical Research Council