Vertex routing models

A class of models describing the flow of information within networks via routing processes is proposed and investigated, concentrating on the effects of memory traces on the global properties. The long-term flow of information is governed by cyclic attractors, allowing to define a measure for the information centrality of a vertex given by the number of attractors passing through this vertex. We find the number of vertices having a non-zero information centrality to be extensive/sub-extensive for models with/without a memory trace in the thermodynamic limit. We evaluate the distribution of the number of cycles, of the cycle length and of the maximal basins of attraction, finding a complete scaling collapse in the thermodynamic limit for the latter. Possible implications of our results on the information flow in social networks are discussed.Comment: 12 pages, 6 figure

Recent US Patterns and Predictors of Prevalent Diabetes among Acute Myocardial Infarction Patients

Background. Diabetes mellitus (DM) confers high vascular risk and is a growing national epidemic. We assessed clinical characteristics and prevalence of diagnosed DM among patients hospitalized with acute myocardial infarction (AMI) in the US over the last decade. Methods. Data were obtained from all states within the US that contributed to the Nationwide Inpatient Sample. All patients admitted to hospitals between 1997 and 2006 with a primary discharge diagnosis of AMI were included. Time trends in the proportion of these patients with DM diagnosis were computed. Results. The portion of patients with comorbid diabetes among AMI hospitalizations increased substantially from 18% in 1997 to 30% in 2006 (P < .0001). Absolute numbers of AMI hospitalizations in the US decreased 8% (from 729, 412 to 672, 243), while absolute numbers of AMI hospitalizations with coexisting DM rose 51% ((131, 189 to 198, 044), both (P < .0001). Women with AMI were significantly more likely to have DM than similarly aged men, but these differences diminished with increasing age. Conclusion. Although overall hospitalizations for AMI in the US diminished over the last decade, prevalence of diabetes rose substantially. This may have important consequences for the future societal vascular disease burden

Las actitudes de los padres sobre la adaptación de los niños a la institución preescolar

The aim of this research study is to examine parents´ attitudes towards the process of children´s adjustment to a pre-school institution, as well as towards separation difficulties which are encountered when a child starts attending kindergarten. Research results provide answers to whether parents are familiar with the problems manifested in the children´s adjustment process, as well as with the possibilities of successfully overcoming such issues. The research included 763 parents of pre-school children in the territory of Serbia. The differences in parents´ attitudes have been analysed relative to their sex, education and age. In the course of research the authors resorted to a five-point Likert scale composed of 16 items grouped into the following categories: factors which influence the process of adjustment, indicators of a successfully completed adjustment process and methods for overcoming the issues raised in the process of children´s adjustment to a pre-school institution. Parents believe that children´s satisfaction when they attend kindergarten is a more significant indicator of a successfully completed adjustment process relative to the absence of crying and deprecation, as well as that for the purposes of overcoming the difficulties which occur when children start attending a pre-school institution parents most frequently introduce preschool teachers to their child´s habits and traits, and later talk with the child about events in the kindergarten. Research results indicate the presence of statistically significant differences in parents´ attitudes relative to their sex, i.e. they indicate that the adjustment period is more stressful for mothers than for fathers.El objetivo de la investigación es examinar las actitudes de los padres sobre el proceso de adaptación de los niños a la institución preescolar, y también las dificultades de separación que ocurren con el ingreso del niño en jardín de infantes. Los resultados del estudio proponen respuestas a las preguntas si los padres están familiarizados con los problemas que se manifiestan en el proceso de adaptación de los niños a la institución preescolar, y también preguntas sobre las posibilidades de su superación exitosa. El estudio involucró a 763 padres de niños en edad preescolar de Serbia. Se analizan las diferencias en las actitudes de los padres en relación con el género, el nivel de educación y la edad. En la investigación fue utilizada una escala de evaluación de Likert de cinco pasos, compuesta por 16 ítems agrupados en las siguientes categorías: factores que intervienen en el proceso de adaptación, indicadores de una adaptación exitosa y métodos para superar los problemas que surgen en el proceso de adaptación de los niños a la institución preescolar. Los padres lo consideran que la satisfacción de los niños cuando van al jardín de infantes representa un indicador muy importante de la finalización exitosa del proceso de adaptación en relación a la ausencia de llanto y resentimiento, y de que los padres, para superar las dificultades que ocurren cuando niños empiezan a ir en el jardín de infantes, a menudo se reúnen con maestros para familiarizarlos con los costumbres y las características de sus hijos, y luego hablan con sus hijos sobre los acontecimientos en el jardín de infancia. Los resultados del estudio indican que existen unas diferencias estadísticamente significativas en las actitudes de los padres con respecto al género, es decir, el período de adaptación es más estresante para las madres que para los padres

Size distribution of alkyl amines in continental particulate matter and their online detection in the gas and particle phase

An ion chromatographic method is described for the quantification of the simple alkyl amines: methylamine (MA), dimethylamine (DMA), trimethylamine (TMA), ethylamine (EA), diethylamine (DEA) and triethylamine (TEA), in the ambient atmosphere. Limits of detection (3σ) are in the tens of pmol range for all of these amines, and good resolution is achieved for all compounds except for TMA and DEA. The technique was applied to the analysis of time-integrated samples collected using a micro-orifice uniform deposition impactor (MOUDI) with ten stages for size resolution of particles with aerodynamic diameters between 56 nm and 18 μm. In eight samples from urban and rural continental airmasses, the mass loading of amines consistently maximized on the stage corresponding to particles with aerodynamic diameters between 320 and 560 nm. The molar ratio of amines to ammonium (R&lt;sub&gt;3&lt;/sub&gt;NH&lt;sup&gt;+&lt;/sup&gt;/NH&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt;) in fine aerosol ranged between 0.005 and 0.2, and maximized for the smallest particle sizes. The size-dependence of the R&lt;sub&gt;3&lt;/sub&gt;NH&lt;sup&gt;+&lt;/sup&gt;/NH&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt; ratio indicates differences in the relative importance of the processes leading to the incorporation of amines and ammonia into secondary particles. The technique was also used to make simultaneous hourly online measurements of amines in the gas phase and in fine particulate matter using an Ambient Ion Monitor Ion Chromatograph (AIM-IC). During a ten day campaign in downtown Toronto, DMA, TMA + DEA, and TEA were observed to range from below detection limit to 2.7 ppt in the gas phase. In the particle phase, MAH&lt;sup&gt;+&lt;/sup&gt; and TMAH&lt;sup&gt;+&lt;/sup&gt; + DEAH&lt;sup&gt;+&lt;/sup&gt; were observed to range from below detection limit up to 15 ng m&lt;sup&gt;−3&lt;/sup&gt;. The presence of detectable levels of amines in the particle phase corresponded to periods with higher relative humidity and higher mass loadings of nitrate. While the hourly measurements made using the AIM-IC provide data that can be used to evaluate the application of gas-particle partitioning models to amines, the strong size-dependence of the R&lt;sub&gt;3&lt;/sub&gt;NH&lt;sup&gt;+&lt;/sup&gt;/NH&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt; ratio indicates that using bulk measurements may not be appropriate

Surface Transformations and Water Uptake on Liquid and Solid Butanol near the Melting Temperature

Water interactions with organic surfaces are of central importance in biological systems and many Earth system processes. Here we describe experimental studies of water collisions and uptake kinetics on liquid and solid butanol from 160 to 200 K. Hyperthermal D2O molecules (0.32 eV) undergo efficient trapping on both solid and liquid butanol, and only a minor fraction scatters inelastically after an 80% loss of kinetic energy to surface modes. Trapped molecules either desorb within a few ms, or are taken up by the butanol phase during longer times. The water uptake and surface residence time increase with temperature above 180 K indicating melting of the butanol surface 4.5 K below the bulk melting temperature. Water uptake changes gradually across the melting point and trapped molecules are rapidly lost by diffusion into the liquid above 190 K. This indicates that liquid butanol maintains a surface phase with limited water permeability up to 5.5 K above the melting point. These surface observations are indicative of an incremental change from solid to liquid butanol over a range of 10 K straddling the bulk melting temperature, in contrast to the behavior of bulk butanol and previously studied materials.Comment: 28 pages, 4 figures + introduction figur

Therapeutic Potential of Mesenchymal Stem Cells and Their Secretome in the Treatment of Glaucoma.

Glaucoma represents a group of progressive optic neuropathies characterized by gradual loss of retinal ganglion cells (RGCs), the neurons that conduct visual information from the retina to the brain. Elevated intraocular pressure (IOP) is considered the main reason for enhanced apoptosis of RGCs in glaucoma. Currently used therapeutic agents are not able to repopulate and/or regenerate injured RGCs and, therefore, are ineffective in most patients with advanced glaucoma. Accordingly, several new therapeutic approaches, including stem cell-based therapy, have been explored for the glaucoma treatment. In this review article, we emphasized current knowledge regarding molecular and cellular mechanisms responsible for beneficial effects of mesenchymal stem cells (MSCs) and their secretome in the treatment of glaucoma. MSCs produce neurotrophins and in an exosome-dependent manner supply injured RGCs with growth factors enhancing their survival and regeneration. Additionally, MSCs are able to generate functional RGC-like cells and induce proliferation of retinal stem cells. By supporting integrity of trabecular meshwork, transplanted MSCs alleviate IOP resulting in reduced loss of RGCs. Moreover, MSCs are able to attenuate T cell-driven retinal inflammation providing protection to the injured retinal tissue. In summing up, due to their capacity for neuroprotection and immunomodulation, MSCs and their secretome could be explored in upcoming clinical studies as new therapeutic agents for glaucoma treatment

The Field-Tuned Superconductor-Insulator Transition with and without Current Bias

The magnetic-field-tuned superconductor-insulator transition has been studied in ultrathin Beryllium films quench-condensed near 20 K. In the zero-current limit, a finite-size scaling analysis yields the scaling exponent product vz = 1.35 +/- 0.10 and a critical sheet resistance R_{c} of about 1.2R_{Q}, with R_{Q} = h/4e^{2}. However, in the presence of dc bias currents that are smaller than the zero-field critical currents, vz becomes 0.75 +/- 0.10. This new set of exponents suggests that the field-tuned transitions with and without dc bias currents belong to different universality classes.Comment: RevTex 4 pages, 4 figures, and 1 table minor change

Fabrication of One-Dimensional Programmable-Height Nanostructures via Dynamic Stencil Deposition

Dynamic stencil deposition (DSD) techniques offer a variety of fabrication advantages not possible with traditional lithographic processing, such as the the ability to directly deposit nanostructures with programmable height profiles. However, DSD systems have not enjoyed widespread usage due to their complexity. We demonstrate a simple, low-profile, portable, one-dimensional nanotranslation system that facilitates access to nanoscale DSD abilities. Furthermore we show a variety of fabricated programmable-height nanostructures, including parallel arrays of such structures, and suggest other applications that exploit the unique capabilities of DSD fabrication methods.Comment: 6 pages, 5 figure