Effects of Diversity and Procrastination in Priority Queuing Theory: the Different Power Law Regimes

Empirical analysis show that, after the update of a browser, the publication of the vulnerability of a software, or the discovery of a cyber worm, the fraction of computers still using the older version, or being not yet patched, or exhibiting worm activity decays as power laws $\sim 1/t^{\alpha}$ with $0 < \alpha \leq 1$ over time scales of years. We present a simple model for this persistence phenomenon framed within the standard priority queuing theory, of a target task which has the lowest priority compared with all other tasks that flow on the computer of an individual. We identify a "time deficit" control parameter $\beta$ and a bifurcation to a regime where there is a non-zero probability for the target task to never be completed. The distribution of waiting time ${\cal T}$ till the completion of the target task has the power law tail $\sim 1/t^{1/2}$, resulting from a first-passage solution of an equivalent Wiener process. Taking into account a diversity of time deficit parameters in a population of individuals, the power law tail is changed into $1/t^\alpha$ with $\alpha\in(0.5,\infty)$, including the well-known case $1/t$. We also study the effect of "procrastination", defined as the situation in which the target task may be postponed or delayed even after the individual has solved all other pending tasks. This new regime provides an explanation for even slower apparent decay and longer persistence.Comment: 32 pages, 10 figure

The Darkening Cloud of Diabetes: Do trends in cardiovascular risk management provide a silver lining?

OBJECTIVE—We aimed to evaluate the changes in cardiovascular-related health care utilization (drug therapies, hospitalizations) and mortality for the diabetic population during a 9-year period in Saskatchewan, Canada

Causal trajectories description of atom diffraction by surfaces

9 pages, 7 figures -- PACS numbers: 79.20.Rf, 03.65.Sq, 03.65.BzThe method of quantum trajectories proposed by de Broglie and Bohm is applied to the study of atom diffraction by surfaces. As an example, a realistic model for the scattering of He off corrugated Cu is considered. In this way, the final angular distribution of trajectories is obtained by box-counting, which is in excellent agreement with the results calculated by standard S-matrix methods of scattering theory. More interestingly, the accumulation of quantum trajectories at the different diffraction peaks is explained in terms of the corresponding quantum potential. This non-local potential "guides" the trajectories causing a transition from a distribution near the surface, which reproduces its shape, to the final diffraction pattern observed in the asymptotic region, far from the diffracting object. These two regimes are homologous to the Fresnel and Fraunhofer regions described in undulatory optics. Finally, the turning points of the quantum trajectories provide a better description of the surface electronic density than the corresponding classical ones, usually employed for this task.This work was supported by DGES (Spain) under contracts No PB95-71, PB95-425 and PB96-76. A.S. Sanz also acknowledges the Universidad Autónoma de Madrid for a doctoral grant.Peer reviewe

Модель определения оптимальных траекторий перемещения партий грузов

The suggested model for determining the optimal trajectories of moving consignments that form cargo flows in transport and logistics systems (TLS) is based on a combination of dynamic systems and multi-criteria optimization methods. This approach develops a methodology for solving applied control problems in TLS. Its main result is the principle of finding the maximum, subject to the criterion preferences, based on methods for determining the set of effective plans (Pareto set). At the same time, management in TLS should form models of cargo traffic taking into account the location of transport and storage complexes within the boundaries of the system being studied or designed, as well as should provide for movement of consignments according to specified performance criteria and the most rational trajectories using analytical modeling. Analytics together with digital technologies help to consider the core sense of TLS as of a subsystem of intelligent transport systems.Представленная модель определения оптимальных траекторий перемещения партий грузов, формирующих грузопотоки в транспортно-логистических системах (ТЛС), основана на совмещении динамических систем и методов многокритериальной оптимизации. Данный подход развивает методологию решения прикладных задач управления в ТЛС, центральным результатом которой является принцип нахождения максимума при условии соблюдения критериальных предпочтений, базирующийся на эффективном средстве решения проблемы – методах определения множества эффективных планов (множества Парето). При этом управление в ТЛС формирует модели грузопотоков с учётом месторасположения транспортно-складских комплексов в границах исследуемой или проектируемой системы и обеспечивает движение партий грузов по заданным критериям эффективности и наиболее рациональным траекториям с помощью методов аналитического моделирования. Аналитика в совокупности с цифровыми технологиями помогает увидеть суть ТЛС как подсистемы интеллектуальных транспортных систем

Macromolecular theory of solvation and structure in mixtures of colloids and polymers

The structural and thermodynamic properties of mixtures of colloidal spheres and non-adsorbing polymer chains are studied within a novel general two-component macromolecular liquid state approach applicable for all size asymmetry ratios. The dilute limits, when one of the components is at infinite dilution but the other concentrated, are presented and compared to field theory and models which replace polymer coils with spheres. Whereas the derived analytical results compare well, qualitatively and quantitatively, with mean-field scaling laws where available, important differences from ``effective sphere'' approaches are found for large polymer sizes or semi-dilute concentrations.Comment: 23 pages, 10 figure

How spiking neurons give rise to a temporal-feature map

A temporal-feature map is a topographic neuronal representation of temporal attributes of phenomena or objects that occur in the outside world. We explain the evolution of such maps by means of a spike-based Hebbian learning rule in conjunction with a presynaptically unspecific contribution in that, if a synapse changes, then all other synapses connected to the same axon change by a small fraction as well. The learning equation is solved for the case of an array of Poisson neurons. We discuss the evolution of a temporal-feature map and the synchronization of the single cells’ synaptic structures, in dependence upon the strength of presynaptic unspecific learning. We also give an upper bound for the magnitude of the presynaptic interaction by estimating its impact on the noise level of synaptic growth. Finally, we compare the results with those obtained from a learning equation for nonlinear neurons and show that synaptic structure formation may profit from the nonlinearity

Treatment of Type 2 Diabetes and Outcomes in Patients With Heart Failure: A Nested Case–Control Study From the U.K. General Practice Research Database

OBJECTIVE - Diabetes and heart failure commonly coexist, and prior studies have suggested better outcomes with met formin than other antidiabetic agents. We designed this study to determine whether this association reflects a beneficial effect of metformin or a harmful effect of other agents. RESEARCH DESIGN AND METHODS - We performed a case-control study nested within the U.K. General Practice Research Database cohort in which diagnoses were assigned by each patient's primary care physician. Case subjects were patients 35 years or older, newly diagnosed with both heart failure and diabetes after January 1988, and who died prior to October 2007. Control subjects were matched to case subjects based on age, sex, clinic site, calendar year, and duration of follow-up. Analyses were adjusted for comorbidities, A1C, renal function, and BMI. RESULTS - The duration of concurrent diabetes and heart failure was 2.8 years (SD 2.6) in our 1,633 case subjects and 1,633 control subjects (mean age 78 years, 53% male). Compared with patients who were not exposed to antidiabetic drugs, the current use of metformin monotherapy (adjusted odds ratio 0.65 [0.48-0.87]) or metformin with or without other agents (0.72 [0.59-0.90]) was associated with lower mortality; however, use of other antidiabetic drugs or insulin was not associated with all-cause mortality. Conversely, the use of ACE inhibitors/angiotensin receptor blockers (0.55 [0.45-0.68]) and beta-blockers (0.76 [0.61-0.95]) were associated with reduced mortality. CONCLUSIONS - Our results confirm the benefits of trial-proven anti-failure therapies in patients with diabetes and support the use of metformin-based strategies to lower glucose

Desenvolvimento de geleia light de abacaxi com hortelã.

A geleia desenvolvida é um produto com potencial funcional ? contem abacaxi e hortelã ? que tem ação benéfica para a saúde. O objetivo da pesquisa foi sugerir ao consumidor brasileiro uma ?geleia light? ? menos açúcar e calorias ? contendo alta proporção de polpa de abacaxi e a hortelã como ingredientes saudáveis. O Processo4 se caracterizou por ter uma representação, por 100g de geleia, dos ingredientes alimentícios seguintes: 160g de abacaxi Pérola, 4g de hortelã, 2g de pectina cítrica e 30g de açúcar. A geleia do Processo4, por apresentar textura própria de geleia, agradável sabor e aparência de hortelã, bem como sabor característico de polpa de abacaxi, foi avaliada quanto à aceitação sensorial (aparência, textura, sabor, percepção da fruta) e intenção de compra. Um total de 83,7% dos avaliadores declararam que gostaram da geleia light, e, dos 81,9% que consomem geleia, 75,3% comprariam esse produto. A geleia light de abacaxi com hortelã apresentou redução de 50% de açúcar e 50% de calorias atribuídas ao açúcar. Assim, uma porção de 20g dessa geleia light (30ºbrix) possui 6g de carboidrato e 24kcal, enquanto que, da geleia convencional de 60ºbrix, 12g de carboidrato e 48kcal. Também, por ter uma alta representação de polpa de abacaxi Pérola (160g.100g-1) possui um teor mais alto de vitamina C (2,6mg.100g-1). Assim, a pesquisa atual disponibiliza ao mercado uma ?geleia light de abacaxi com hortelã? que tem relevância para a saúde do consumidor, visto que possui reduzido índice de carboidrato e calorias e seus ingredientes apresentam ação positiva para a saúde