Hybrid Statistical Data Mining Framework for Multi-Commodity Fixed Charge Network Flow Problem

This paper presents a new approach to analyze the network structure in multi-commodity fixed charge network flow problems (MCFCNF). This methodology uses historical data produced from repeatedly solving the traditional MCFCNF mathematical model as input for the machine-learning framework. Further, we reshape the problem as a binary classification problem and employ machine-learning algorithms to predict network structure. This predicted network structure is further used as an initial solution for our mathematical model. The quality of the initial solution generated is judged on the basis of predictive accuracy, feasibility and reduction in solving time

Disease-modifying therapy adherence and associated factors in a national sample of Medicare patients with multiple sclerosis

OBJECTIVES: Disease-modifying therapies (DMTs) reduce relapse rates and disability progression for relapsing multiple sclerosis (MS). Although 25% to 30% of all US patients with MS are Medicare beneficiaries, limited information exists on this population. This is the first study using national Medicare data to (1) describe characteristics of patients with MS using DMTs, (2) estimate adherence to DMTs over a 1-year and 3-year follow-up, and (3) examine factors associated with DMT adherence. METHODS: This retrospective claims analysis used 2011-2014 100% Medicare files. Monthly adherence to MS DMTs was defined as the proportion of days covered ≥0.80 with any DMT in each month for 1-year (n = 36 593) and 3-year (n = 17 599) follow-up samples of MS DMT users. Generalized estimating equation logistic regressions were used to estimate factors associated with adherence to DMTs. RESULTS: Over 90% of patients were eligible for Medicare owing to disability, and about three-quarters qualified for low-income subsidies. A downward trend in DMT adherence was observed over time in both samples. Monthly adherence dropped significantly between December of the prior year to January of the following year (from 76% to 65% in the 1-year follow-up sample and similar drops seen across all years in the 3-year follow-up sample). Multivariable regressions indicated characteristics such as being low-income, having a disability, and having high patient out-of-pocket DMT costs associated with poor adherence to DMTs. CONCLUSION: Our study provides important insights into the characteristics and DMT adherence of Medicare patients with MS and highlights the need for interventions and policies mitigating barriers to adherence in this population

C.elegans as a Diabetes & Ischemia Model: Identification of Genetic and Cellular Changes that Modulate the Survival of Hyperglycemia and Oxygen-Deprivation

Diet represents an exogenous influence that often yields colossal effects on an individual’s phenotype, physiology, long-term health and disease risk. The overconsumption of dietary sugars for example, has contributed to significant increases in obesity and type 2 diabetes, health issues that are costly both in terms of dollars and human life. Additionally, individuals with these conditions have compromised oxygen delivery and thus, an increased vulnerability to other oxygen-deprivation related disease states, including cardiovascular disease, ischemic strokes, vascular and coronary diseases and myocardial infarction. While human and other mammalian studies have shown that individuals with type 2 diabetes have a worse prognosis and recovery after being challenged with an oxygen-deprivation related injury, mechanistic understanding regarding why this is the case is lacking. We are using C. elegans to identify genetic and cellular changes that modulate responses to the combinatory stress of hyperglycemia and oxygen-deprivation. We have determined that C. elegans fed a high glucose diet have increased cellular glucose (hyperglycemia), increased lipid content and increased sensitivity to oxygen-deprivation (anoxia) and ROS induction. We have determined that the insulin-like signaling pathway, via fatty acid and ceramide synthesis, modulates the increased sensitivity to anoxia. In mammalian systems, specific ceramide species increase after an ischemic event and are also linked to detrimental effects observed in diabetic patients, underscoring the potential role these molecules have in modulating oxygen-deprivation and hyperglycemia responses in individuals. Specific fatty acids also have known roles as both signaling molecules and as integral membrane components, thus, we hypothesize that a high-glucose diet disrupts fatty acid and ceramide homeostasis resulting in aberrations in metabolic processes and stress response pathways that are essential for the survival of oxygen-deprivation. Additionally, gene expression analysis (via RNAseq) on C. elegans fed either a standard or glucose-supplemented diet revealed that glucose impacts the expression of genes involved with multiple cellular processes, including lipid and carbohydrate metabolism, stress responses, cell division and extracellular functions. Several of the genes we identified are also differentially regulated in obese and type-2 diabetic human individuals, indicating a high degree of conserved gene expression changes between C. elegans fed a glucose-supplemented diet and in diabetic and/or obese human individuals. Together this work underscores how both diet and genotype impact stress responses and supports the use of C. elegans as a model for further elucidating the molecular mechanisms regulating dietary-induced metabolic diseases

Scale-free memory model for multiagent reinforcement learning. Mean field approximation and rock-paper-scissors dynamics

A continuous time model for multiagent systems governed by reinforcement learning with scale-free memory is developed. The agents are assumed to act independently of one another in optimizing their choice of possible actions via trial-and-error search. To gain awareness about the action value the agents accumulate in their memory the rewards obtained from taking a specific action at each moment of time. The contribution of the rewards in the past to the agent current perception of action value is described by an integral operator with a power-law kernel. Finally a fractional differential equation governing the system dynamics is obtained. The agents are considered to interact with one another implicitly via the reward of one agent depending on the choice of the other agents. The pairwise interaction model is adopted to describe this effect. As a specific example of systems with non-transitive interactions, a two agent and three agent systems of the rock-paper-scissors type are analyzed in detail, including the stability analysis and numerical simulation. Scale-free memory is demonstrated to cause complex dynamics of the systems at hand. In particular, it is shown that there can be simultaneously two modes of the system instability undergoing subcritical and supercritical bifurcation, with the latter one exhibiting anomalous oscillations with the amplitude and period growing with time. Besides, the instability onset via this supercritical mode may be regarded as "altruism self-organization". For the three agent system the instability dynamics is found to be rather irregular and can be composed of alternate fragments of oscillations different in their properties.Comment: 17 pages, 7 figur

Photoproduction of ϱo on hydrogen with tagged photons between 4 and 6 GeV

We have measured the reaction γp → pπ+π− in the DESY 1 m Streamer Chamber. The dominant ϱo production is analyzed in terms of various models

Measurement of the diffractive structure function in deep inelastic scattering at HERA

This paper presents an analysis of the inclusive properties of diffractive deep inelastic scattering events produced in $ep$ interactions at HERA. The events are characterised by a rapidity gap between the outgoing proton system and the remaining hadronic system. Inclusive distributions are presented and compared with Monte Carlo models for diffractive processes. The data are consistent with models where the pomeron structure function has a hard and a soft contribution. The diffractive structure function is measured as a function of \xpom, the momentum fraction lost by the proton, of $\beta$, the momentum fraction of the struck quark with respect to \xpom, and of $Q^2$. The \xpom dependence is consistent with the form \xpoma where $a~=~1.30~\pm~0.08~(stat)~^{+~0.08}_{-~0.14}~(sys)$ in all bins of $\beta$ and $Q^2$. In the measured $Q^2$ range, the diffractive structure function approximately scales with $Q^2$ at fixed $\beta$. In an Ingelman-Schlein type model, where commonly used pomeron flux factor normalisations are assumed, it is found that the quarks within the pomeron do not saturate the momentum sum rule.Comment: 36 pages, latex, 11 figures appended as uuencoded fil

Observation of hard scattering in photoproduction events with a large rapidity gap at HERA

Events with a large rapidity gap and total transverse energy greater than 5 GeV have been observed in quasi-real photoproduction at HERA with the ZEUS detector. The distribution of these events as a function of the $\gamma p$ centre of mass energy is consistent with diffractive scattering. For total transverse energies above 12 GeV, the hadronic final states show predominantly a two-jet structure with each jet having a transverse energy greater than 4 GeV. For the two-jet events, little energy flow is found outside the jets. This observation is consistent with the hard scattering of a quasi-real photon with a colourless object in the proton.Comment: 19 pages, latex, 4 figures appended as uuencoded fil

Limits of the seismogenic zone in the epicentral region of the 26 December 2004 great Sumatra-Andaman earthquake: Results from seismic refraction and wide-angle reflection surveys and thermal modeling

The 26 December 2004 Sumatra earthquake (Mw = 9.1) initiated around 30 km depth and ruptured 1300 km of the Indo-Australian Sunda plate boundary. During the Sumatra OBS (ocean bottom seismometer) survey, a wide angle seismic profile was acquired across the epicentral region. A seismic velocity model was obtained from combined travel time tomography and forward modeling. Together with reflection seismic data from the SeaCause II cruise, the deep structure of the source region of the great earthquake is revealed. Four to five kilometers of sediments overlie the oceanic crust at the trench, and the subducting slab can be imaged down to a depth of 35 km. We find a crystalline backstop 120 km from the trench axis, below the fore arc basin. A high velocity zone at the lower landward limit of the raycovered domain, at 22 km depth, marks a shallow continental Moho, 170 km from the trench. The deep structure obtained from the seismic data was used to construct a thermal model of the fore arc in order to predict the limits of the seismogenic zone along the plate boundary fault. Assuming 100C-150C as its updip limit, the seismogenic zone is predicted to begin 530 km from the trench. The downdip limit of the 2004 rupture as inferred from aftershocks is within the 350C 450C temperature range, but this limit is 210-250 km from the trench axis and is much deeper than the fore arc Moho. The deeper part of the rupture occurred along the contact between the mantle wedge and the downgoing plate

Spatial Orientation in Japanese Quails (Coturnix coturnix japonica)

Finding a given location can be based on a variety of strategies, for example on the estimation of spatial relations between landmarks, called spatial orientation. In galliform birds, spatial orientation has been demonstrated convincingly in very young domestic chicks. We wanted to know whether adult Japanese quails (Coturnix coturnix japonica) without food deprivation are also able to use spatial orientation. The quails had to learn the relation of a food location with four conspicuous landmarks which were placed in the corners of a square shaped arena. They were trained to find mealworms in three adjacent food cups in a circle of 20 such cups. The rewarded feeders were located during training between the same two landmarks each of which showed a distinct pattern. When the birds had learned the task, all landmarks were displaced clockwise by 90 degrees. When tested in the new situation, all birds redirected their choices with respect to the landmark shift. In subsequent tests, however, the previously correct position was also chosen. According to our results, quails are using conspicuous landmarks as a first choice for orientation. The orientation towards the previously rewarded location, however, indicates that the neuronal representation of space which is used by the birds also includes more fine grain, less conspicuous cues, which are probably also taken into account in uncertain situations. We also presume that the rare orientation towards never rewarded feeders may be due to a foraging strategy instead of being mistakes