A generalized Pólya urn and limit laws for the number of outputs in a family of random circuits

We introduce a generalized Pólya urn model with the feature that the evolution of the urn is governed by a function which may change depending on the stage of the process, and we obtain a Strong Law of Large Numbers and a Central Limit Theorem for this model, using stochastic recurrence techniques. This model is used to represent the evolution of a family of acyclic directed graphs, called random circuits, which can be seen as logic circuits. The model provides asymptotic results for the number of outputs, that is, terminal nodes, of this family of random circuits.     

Activity logging using lightweight classification techniques in mobile devices

Automated activity recognition enables a wide variety of applications related to child and elderly care, disease diagnosis and treatment, personal health or sports training, for which it is key to seamlessly determine and log the user’s motion. This work focuses on exploring the use of smartphones to perform activity recognition without interfering in the user’s lifestyle. Thus, we study how to build an activity recognition system to be continuously executed in a mobile device in background mode. The system relies on device’s sensing, processing and storing capabilities to estimate significant movements/postures (walking at different paces—slow, normal, rush, running, sitting, standing). In order to evaluate the combinations of sensors, features and algorithms, an activity dataset of 16 individuals has been gathered. The performance of a set of lightweight classifiers (Naïve Bayes, Decision Table and Decision Tree) working on different sensor data has been fully evaluated and optimized in terms of accuracy, computational cost and memory fingerprint. Results have pointed out that a priori information on the relative position of the mobile device with respect to the user’s body enhances the estimation accuracy. Results show that computational low-cost Decision Tables using the best set of features among mean and variance and considering all the sensors (acceleration, gravity, linear acceleration, magnetometer, gyroscope) may be enough to get an activity estimation accuracy of around 88 % (78 % is the accuracy of the Naïve Bayes algorithm with the same characteristics used as a baseline). To demonstrate its applicability, the activity recognition system has been used to enable a mobile application to promote active lifestyles.     

Dynamic Accessibility using Big Data: The Role of the Changing Conditions of Network Congestion and Destination Attractiveness

Accessibility is essentially a dynamic concept. However, most studies on urban accessibility take a static approach, overlooking the fact that accessibility conditions change dramatically throughout the day. Due to their high spatial and temporal resolution, the new data sources (Big Data) offer new possibilities for the study of accessibility. The aim of this paper is to analyse urban accessibility considering its two components –the performance of the transport network and the attractiveness of the destinations– using a dynamic approach using data from TomTom and Twitter respectively. This allows us to obtain profiles that highlight the daily variations in accessibility in the city of Madrid, and identify the influence of congestion and the changes in location of the population. These profiles reveal significant variations according to transport zones. Each transport zone has its own accessibility profile, and thus its own specific problems, which require solutions that are also specific.     

Psychopedagogical components and processes in e-learning. Lessons from an unsuccessful on-line course

In this study we are reporting the results of an external evaluation carried out on an experimental on-line course developed as part of the European project Multidimensional Approach for Multiplication of Training Environments (MAMUT) (E/99/1/61440/PI/III.3.a/CONT). The aim was to identify psychopedagogical processes that might influence the dynamics of the on-line course and to detect unexpected results. Qualitative analysis of the content of the three hundred and fifty six (356) messages written by the participants in the virtual environment was undertaken. The aspects analysed were: Adaptation to Virtual Environment, Content, Resources, Timing, Tasks, Students’ characteristics, Students’ interaction, and Students-Facilitator interaction.     

Random Riemann Sum estimator versus Monte Carlo

Two estimators of the expectation of a function, the classical based in Monte Carlo sampling method and one based in Random Riemann Sums, are compared. It presents the differences on bias, variance, convergence and mainly convergence rates. Two ways of sampling to obtain a Random Riemann Sum estimator are given. The first one provides a sequence of estimations whose terms are independent, this fact produces a loss of order one in the convergence rate for the strong law compared with Monte Carlo sampling method. The second one is considered in order to improve these results.     

Effect of moisture content, particle size and pine addition on quality parameters of barley straw pellets

Agripellets from barley straw wastes have been produced in an annular die pellet mill. The semi-industrial scale of the pilot plant allowed for measurement of the die temperature, and an accurate control of the straw moisture at the die inlet. The pellet mechanical durability, density, length and moisture were evaluated for pure straw and blended pellets, together with the heating value and the ash content. The composition of the raw material barely changed with the compaction process. Optimum moisture contents for dense barley straw pellets production proved to be in the range of 19-23%. A durability value of 95.5% was reached under these conditions, increasing to 97-98% when small quantities of pine sawdust were added (2, 7, and 12 wt.% of pine in straw). Agglomeration of the ground particles was improved by water and pine addition, while a coarser grinding did not show any negative effect on barley straw compaction.     

Machining FEM model of long fiber composites for aeronautical components

This work is focused on the study of orthogonal cutting of long fiber composites. A model based in finite element was developed. The mechanisms of chip formation of Glass and Carbon Fiber Reinforced Polymer (FRP) composites were analyzed. Significant differences were observed when comparing machining induced damage predicted with the model for both materials. While damage extended widely ahead the interface and beneath the tool tip in the case of GFRP, damage was located in a much smaller zone in the case CFRP. The fiber orientation influences both the mechanism of chip formation and the induced subsurface damage.     

Generation of null alleles for the functional analysis of six genes from the right arm of Saccharomyces cerevisiae chromosome II

Using PCR‐ligated long flanking homology cassettes, null alleles of six open reading frames (ORFs) from chromosome II have been created in Saccharomyces cerevisiae. Deletants were constructed in three genetic backgrounds: FY1679, W303 and CEN.PK2. Tetrad analysis of heterozygous deletants revealed that none of the ORFs is essential for vegetative growth. Basic phenotypic analysis of haploid deletants showed that deletion of the YBR283c ORF causes a slight growth defect at 30°C and 37°C on glycerol‐complete, glucose‐complete, and glucose‐minimal media only in the FY1679 and W303 backgrounds. Transformation of these deletants with the corresponding cognate gene in a centromeric plasmid complements the defects. Deletion of the YBR287w ORF leads to poor growth on glucose‐minimal medium at 15°C in the FY1679 background. None of the six ORFs seems to be involved in mating or sporulation. Copyright © 1999 John Wiley & Sons, Ltd.     

Sensitivity of selected bacterial species to UV radiation

The effect of exposure of bacterial suspensions to UV radiation by means of the dose-response curves was assessed. The D37 and D10 values were used for subsequent statistical analysis of the results. The aim of this article is to evaluate the sensitivity to UV radiation of several microorganisms of different habitats (Rhizobium meliloti, Rhodobacter sphaeroides, Escherichia coli, and Deinococcus radiodurans), two mutants with nonfunctional SOS DNA repair system (R. meliloti recA- and E. coli recA-), and a mutant in the synthesis of carotenoids (R. sphaeroides crtD). The results reveal that D. radiodurans was an extremely resistant bacterium, R. meliloti was more resistant than R. sphaeroides, and E. coli was the most sensitive bacterium tested. The high sensitivity of recA- mutants was also verify. Moreover, it seems that the possession of pigments had no important effect in the sensitivity of R. sphaeroides to UV radiation.     

Chronic non granulomatous ulcerative jejunitis

BACKGROUND: Early human immunodeficiency virus (HIV) defection is essential for initiating treatment and partner-notification activities. Sexually transmitted disease (STD) clinic attendees are at high risk for infection and should be made aware of their HIV status. GOAL: To determine the characteristics associated with not receiving an HIV test result in an STD clinic setting. STUDY DESIGN: Confidential HIV testing was offered to 6,705 persons attending four public STD clinics in Los Angeles who submitted blood for syphilis serology and were tested for HIV antibody in an unlinked HIV serosurvey. Human immunodeficiency virus test results and return status were anonymously linked to other risk information. RESULTS: Only one-third of attendees were tested and given their results. Those testing HIV positive in the anonymous survey and those requesting HIV testing were most likely to receive a test result (i.e., 41% and 49%, respectively). Those solely requesting an STD examination, repeat testers, and African-Americans were least likely to receive a result (i.e., 32%, 30%, and 26%, respectively). CONCLUSIONS: Most STD clinic patients fail to receive an HIV test result. Other strategies, such as rapid HIV testing, are needed to increase participation and receipt of HIV test results in this high-risk population.