Simulation methods with extended stability for stiff biochemical kinetics

Background: With increasing computer power, simulating the dynamics of complex systems in chemistry and biology is becoming increasingly routine. The modelling of individual reactions in (bio)chemical systems involves a large number of random events that can be simulated by the stochastic simulation algorithm (SSA). The key quantity is the step size, or waiting time, τ, whose value inversely depends on the size of the propensities of the different channel reactions and which needs to be re-evaluated after every firing event. Such a discrete event simulation may be extremely expensive, in particular for stiff systems where τ can be very short due to the fast kinetics of some of the channel reactions. Several alternative methods have been put forward to increase the integration step size. The so-called τ-leap approach takes a larger step size by allowing all the reactions to fire, from a Poisson or Binomial distribution, within that step. Although the expected value for the different species in the reactive system is maintained with respect to more precise methods, the variance at steady state can suffer from large errors as τ grows. Results: In this paper we extend Poisson τ-leap methods to a general class of Runge-Kutta (RK) τ-leap methods. We show that with the proper selection of the coefficients, the variance of the extended τ-leap can be well-behaved, leading to significantly larger step sizes.Conclusions: The benefit of adapting the extended method to the use of RK frameworks is clear in terms of speed of calculation, as the number of evaluations of the Poisson distribution is still one set per time step, as in the original τ-leap method. The approach paves the way to explore new multiscale methods to simulate (bio)chemical systems.

LdShake: learning design solutions sharing and co-edition

Two important challenges that teachers are currently facing are the sharing and the collaborative authoring of their learning design solutions, such as didactical units and learning materials. On the one hand, there are tools that can be used for the creation of design solutions and only some of them facilitate the co-edition. However, they do not incorporate mechanisms that support the sharing of the designs between teachers. On the other hand, there are tools that serve as repositories of educational resources but they do not enable the authoring of the designs. In this paper we present LdShake, a web tool whose novelty is focused on the combined support for the social sharing and co-edition of learning design solutions within communities of teachers. Teachers can create and share learning designs with other teachers using different access rights so that they can read, comment or co-edit the designs. Therefore, each design solution is associated to a group of teachers able to work on its definition, and another group that can only see the design. The tool is generic in that it allows the creation of designs based on any pedagogical approach. However, it can be particularized in instances providing pre-formatted designs structured according to a specific didactic method (such as Problem-Based Learning, PBL). A particularized LdShake instance has been used in the context of Human Biology studies where teams of teachers are required to work together in the design of PBL solutions. A controlled user study, that compares the use of a generic LdShake and a Moodle system, configured to enable the creation and sharing of designs, has been also carried out. The combined results of the real and controlled studies show that the social structure, and the commenting, co-edition and publishing features of LdShake provide a useful, effective and usable approach for facilitating teachers' teamwork.

Current drug discovery strategies against arenavirus infections.

Arenaviruses are a large group of emerging viruses including several causative agents of severe hemorrhagic fevers with high mortality in man. Considering the number of people affected and the currently limited therapeutic options, novel efficacious therapeutics against arenaviruses are urgently needed. Over the past decade, significant advances in knowledge about the basic virology of arenaviruses have been accompanied by the development of novel therapeutics targeting different steps of the arenaviral life cycle. High-throughput, small-molecule screens identified potent and broadly active inhibitors of arenavirus entry that were instrumental for the dissection of unique features of arenavirus fusion. Novel inhibitors of arenavirus replication have been successfully tested in animal models and hold promise for application in humans. Late in the arenavirus life cycle, the proteolytic processing of the arenavirus envelope glycoprotein precursor and cellular factors critically involved virion assembly and budding provide further promising 'druggable' targets for novel therapeutics to combat human arenavirus infection.

Who benefits from parental leave in Spain? : a life course analysis

This paper analyses the extent to which individual and workplacecharacteristics and regional policies influence the use and duration ofparental leave in Spain. The research is based on a sample of 125,165people, and 6,959 parental leaves stemming from the ‘Sample ofWorking Life Histories’ (SWLH), 2006. The SWLH consists of administrative register data which include information from threedifferent sources: Social Security, Municipality and Income TaxRegisters. We adopt a simultaneous equations approach to analyse theuse (logistic regression) and duration (event history analysis) ofparental leave, which allows us to control for endogeneity and censoredobservations. We argue that the Spanish parental leave scheme increases gender and social inequalities insofar as reinforces genderrole specialization, and only encourages the reconciling of work andfamily life among workers with a good position in the labour market(educated employees with high and stable working status).

The impact of labour market status on second and higher-order births. A comparative study of Denmark, Italy, Spain and United Kingdom

This paper investigates the effects of women‘s labour force participation on fertility, as well as the effects of the combined labour force participation of both members of a couple. It specifically focuses on such dimensions as unemployment, earnings, temporary contracts and part-time jobs, and it shows that their effects differ in accordance with national institutions and labour market regulations. Event-history methods and a longitudinal sample of the European Community Household Panel are used in the analyses, concerning the years 1993-2000. The results show that labour market insecurity of one or both members of a couple has a particularly strong impact in reducing birth rates in the Southern European countries studied. The more conventional model of men’s employment combined with housewifery has a positive impact on second or higher order births in United Kingdom, Spain and Italy, while in Denmark the effect is the opposite. These differences are consistent with different national models of combining parental responsibilities and participation by gender across the life course.

The impact of women's educational and economic resources on fertility: Spanish birth cohorts 1901-1950

In this chapter we portray the effects of female education and professional achievement on fertility decline in Spain over the period 1920-1980 (birth cohorts of 1901-1950).A longitudinal econometric approach is used to test the hypothesis that the effects of women’s education in the revaluing of their time had a very significant influence on fertility decline. Although in the historical context presented here improvements in schooling were on a modest scale, they were continuous (with the interruption of the Civil War) and had a significant impact in shaping a model of low fertility in Spain. We also stress the relevance of this result in a context such as the Spanish for which liberal values were absent, fertility control practices were forbidden, and labour force participation of women was politically and socially constrained.

Regional child care availability and fertility decisions in Spain

In this paper I explore two hypotheses: (1) Formal child care availability for children under three has a positive effect across contexts, according to the degree of adaptation of social institutions to changes in gender roles. Event history models with regional fixed effects are applied to data from the European Community Household Panel (1994-2001). The results show a significant and positive effect of regional day care availability on both, first and higher order births, while results are consistent with the second hypothesis only for second or higher order births.

A reassessment of family reunification in Europe. The case of Senegalese couples

Contemporary policy makers in most European destination countriesexpress a great concern about reunification of migrants’ families. Newrestrictions multiply in almost all countries, on the grounds thatmigrants would take advantage of a too lax system and that it wouldfoster an influx of non-desirable migrants. So far, quantitative evidenceis scarce on migrants’ practices in matter of family reunification.Taking advantage of a unique longitudinal dataset that includesSenegalese individuals surveyed both at origin (in Senegal) and inEurope (France, Italy and Spain), we perform event-history analyses toshow three things. First, couple separation is very often a long lastingsituation. Second, when separated because of international migration,wives and husbands do not only reunify in Europe but quite commonlyin Senegal. And third, those who reunify in Europe are those who arethe most adapted or adaptable to the European culture and economy.

Joint determinants of education enrolment and first birth timing in France and West Germany

We examined the reciprocal influence between educational decisions and the timing of first births, using the Family and Fertility Surveys of France and West Germany. Since these two processes are potentially endogenous, we modelled them jointly, using event history models. We hypothesise that the reciprocal impact of educational and fertility careers, as well as the impact of the common determinants of both processes, are gender specific and context specific.The results show a significant endogeneity for women and men in both countries. This endogeneity is stronger for women than for men, while no substantial differences are found between the two countries. Removing this shared and unobserved heterogeneity, the results show a stronger reciprocal impact between the processes for women than for men. A similar impact of being enrolled in education on first birth in both countries is found, while the effect of the birth (and especially of the pregnancy) of the first child on terminating one’s education appeared to be more marked in West Gernany than in France.

El efecto del empleo, el paro y los contratos temporales en la baja fecundidad española de los años 1990

España destaca en el contexto europeo tanto por sus bajos niveles de fecundidad como por sus altos niveles de paro e inestabilidad en el empleo. En este texto se investigan empíricamente los efectos de la participación laboral de las mujeres y de sus parejas sobre la fecundidad, y más específicamente el impacto de los contratos temporales y el desempleo. La perspectiva teórica utilizada se basa en el análisis de los cursos de vida individuales y subraya las influencias del contexto institucional y social. Se utiliza una muestra longitudinal del Panel de Hogares de las Comunidades Europeas, relativa a los años 1994-2001, y métodos de análisis de biografias. Los resultados indican un acusado impacto negativo de la inestabilidad en el empleo, que supone una posposición en el calendario de la fecundidad y una reducción de las tasas de fecundidad. Este efecto depresivo sobre la fecundidad es aún más intenso cuando los dos miembros de la pareja están en situación laboral precaria.

Explaining parental dedication to child care in Spain

The quality of the time dedicated to child care has potential positive effects on children’s life chances. However, the determinants of parental time allocation to child care remain largely unexplored, particularly in context undergoing rapid family change such as Spain. We assess two alternative explanations for differences between parents in the amount of time spent with children. The first, based in the relative resources hypothesis, links variation in time spent with children to the relative attributes (occupation, education or income) of one partner to the other. The second, derived from the social status hypothesis, suggests that variation in time spent with children is attributable to the relative social position of the pair (i.e. higher status couples spend more time with children regardless of within-couple difference).To investigate theses questions, we use a sample of adults (18-50) from the Spanish Time Use Survey (STUS) 2002-2003 (n=7,438). Limiting the analysis to adults who are married or in consensual unions, the STUS allows to assess both the quantity and quality of parental time spent with children. We find little support for the “relative resources hypothesis”. Instead, consistent with the “social status hypothesis”, we find that time spent on child care is attributable to the social position of the couple, regardless of between-parent differences in income of education.

Spotting Translationese in two Corpora of Original and Translated Catalan Texts: an Empirical Approach

This research investigates the phenomenon of translationese in two monolingual comparable corpora of original and translated Catalan texts. Translationese has been defined as the dialect, sub-language or code of translated language. This study aims at giving empirical evidence of translation universals regardless the source language.Traditionally, research conducted on translation strategies has been mainly intuition-based. Computational Linguistics and Natural Language Processing techniques provide reliable information of lexical frequencies, morphological and syntactical distribution in corpora. Therefore, they have been applied to observe which translation strategies occur in these corpora.Results seem to prove the simplification, interference and explicitation hypotheses, whereas no sign of normalization has been detected with the methodology used.The data collected and the resources created for identifying lexical, morphological and syntactic patterns of translations can be useful for Translation Studies teachers, scholars and students: teachers will have more tools to help students avoid the reproduction of translationese patterns. Resources developed will help in detecting non-genuine or inadequate structures in the target language. This fact may imply an improvement in stylistic quality in translations. Translation professionals can also take advantage of these resources to improve their translation quality.

Integració del motor APIS de qüestionaris on-line en una plataforma d'eLearning basada en serveis

El projecte Integració del motor APIS de qüestionaris on-line en una plataformad'eLearning basada en serveis descriu el procés d'anàlisi i implementació del codi necessari per integrar dins de la plataforma d'eLearning SLeD tot el motor d'APIS de manera que SLeD pugui reproduir preguntes o items i exàmens complets o tests dins d'una UOL o unitat d'aprenentatge. Això permetrà dotar a APIS d'un control de sessió d'usuari i permetrà una utilitat que fins ara no tenia, la possibilitat de entrar al món online mitjançant SLeD. Tot aixòs’implementa gràcies a la connexió WebServices amb el mòdul CCSI de CopperCore i SLeD que s'encarrega de donar facilitats al programador de cara a ampliar el ventall d'eines que ofereix aquesta plataforma i fomentar encara més la idea del codi lliure (open source) i la utilitat globalitzadora d'e-Learning.

Zara : elecció i distribució òptima

Zara és una marca relativament jove, molt coneguda i que encara està en expansió! Podria ser Vic una població de negoci interessant per la marca? Compleix les característiques demandades per una multinacional d’aquestes característiques? Manifesta la població interès vers la marca? Aquestes són algunes de les preguntes que ens varem plantejar inicialment.El nostre treball tracta de l’obertura d’una tenda Zara a la ciutat de Vic. Aquest projecte consta de dues grans parts; una primera fase teòrica basada en la recerca d’informació realitzada mitjançant diverses fonts per tal de familiaritzar-nos amb la multinacional Inditex i, més concretament, amb Zara. D’aquesta manera detectar els requisits i necessitats de la marca, així com també les preferències dels habitants de Vic envers la possible obertura d’una nova botiga. D’altra banda, una segona part de tipus més pràctica on identificarem el local adient segons les conclusions extretes i en realitzarem la distribució.Pel que fa a la part teòrica hem utilitzat tres fonts d’informació per tal de poder-les contrastar i extreure’n la millor conclusió possible. En primer lloc ens hem basat en la observació empírica de diferents centres Zara i aquest mètode ens ha servit per extreure les característiques més comunes dels establiments observats. Així, hem obtingut una idea dels requisits que haurà de complir el nostre projecte. Cal destacar que aquesta font informativa l’hem complementat amb una entrevista telefònica a la Sra. Isabel Catoira, membre del departament de comunicació del grup Inditex, que ens ha respòs a algunes qüestions que ens han estat de gran ajuda, tot i que hem de deixar constància que l’empresa no ens ha proporcionat la informació desitjada per motius de confidencialitat i hem hagut d’optar per altres mecanismes. En segon lloc, hem confeccionat una enquesta a una mostra aleatòria de 120 persones que es trobaven en diferents zones de la ciutat de Vic, a partir de la qual hem extret informació sobre les preferències de la gent i hem pogut reafirmar la nostra hipòtesi inicial; Zara és la botiga més sol·licitada de les absents a Vic actualment.Pel que fa a la part pràctica, que tracta del muntatge de Zara al local comercial idoni de Vic, consisteix en l’elecció del local òptim dins les possibilitats disponibles a partir de la informació extreta en la primera part. Una vegada triat el local comercial, hem realitzat el muntatge i distribució de les diferents parts de les que ha de constar la tenda i, posteriorment, hem realitzat un breu anàlisi dels costos de muntatge.Finalment, hem presentat el plànol de distribució i muntatge en forma bidimensional i hem adjuntat una presentació virtual per tal de donar-li al treball un toc més de realitat.

Estudi d'un càmping ecològic

El present projecte té per motiu l’anàlisi d’un hipotètic càmping ecològic i pel qual hem seguit la següent metodologia:Una assessoria ens ha contractat per tal de realitzar un estudi sobre el mercat del càmping al Solsonès ja que un assessor turístic està interessat en instal·lar-hi un càmping. Nosaltres hem decidit estudiar el mercat català del càmping i partint de lacompetència que hem localitzat fer un tipus de càmping amb quelcom d’especial. En aquest cas, hem proposat un càmping destinat per a joves (la majoria de càmpings de la zona són per famílies) i ecològic per tal d’intentar reduir el màxim els costos i fomentar l’ecologisme i la protecció del medi ambient, conceptes molt necessaris avui en dia. Des d’aquí, és on parteix tot el nostre treball.Tanmateix, degut a la dificultat de trobar tota la informació complerta de les diferents variables que componen un càmping com també del temps que hem tingut en fer el treball, nosaltres realitzem un estudi de mercat i també incloem els beneficisestimats (partint de preus hipotètics) que sorgirien dels ingressos dels consumidors com també els costos d’instal·lar els recursos ecològics en els tres principals camps del consum d’un càmping: l’aigua, l’energia i els residus. Així, doncs, no realitzem un anàlisi cost-benefici complet sinó que mostrem quan costa convertir-se en un càmping ecològic i mirem en quan de temps s’amortitzaria tenint en compte que, evidentment, en els anys posteriors el consum seria molt menor degut a l’aprofitament dels recursos que ens ofereix el medi ambient. Pel que fa a la metodologia del treball, hem analitzat dades que hem obtingut a través de diferents fonts; des d’Internet fins a empreses reals que esmentarem a la bibliografia. També hem cregut convenient buscar el terreny (una zona adequada perfonamentar el descans i el temps d’oci) i fer-ne una petita distribució com també estudiar alguns punts de la legislació espanyola i aspectes necessaris per tal d’obtenir la marca ecològica. Hem de destacar també que les dades de costos les hem fet com més reals possibles tenint en compte la mida del càmping com també tots els costos relatius encara que és hipotètic ja que no hem inclòs el consum exacte degut que depèn de moltes variables com quan gasta la gent, quanta gent vindria...I finalment els objectius que volíem concebre a partir d’aquest treball han sigut els següents: materialitzar els alts costos d’instal·lar recursos ecològics encara que també observar com a llarg termini acabava sent més viable, veure el mercat delcàmping a una zona que creiem que encara s’ha de descobrir com és el Solsonès, fomentar els joves a anar més de càmping i altres objectius no tan importants com, per exemple, una major compenetració entre els components del grup i una millora de síntesi i expressió escrita i oral.