Quantification of the neurochemical profile using simulated macromolecule resonances at 3 T.

The broad resonances underlying the entire (1) H NMR spectrum of the brain, ascribed to macromolecules, can influence metabolite quantification. At the intermediate field strength of 3 T, distinct approaches for the determination of the macromolecule signal, previously used at either 1.5 or 7 T and higher, may become equivalent. The aim of this study was to evaluate, at 3 T for healthy subjects using LCModel, the impact on the metabolite quantification of two different macromolecule approaches: (i) experimentally measured macromolecules; and (ii) mathematically estimated macromolecules. Although small, but significant, differences in metabolite quantification (up to 23% for glutamate) were noted for some metabolites, 10 metabolites were quantified reproducibly with both approaches with a Cramer-Rao lower bound below 20%, and the neurochemical profiles were therefore similar. We conclude that the mathematical approximation can provide sufficiently accurate and reproducible estimation of the macromolecule contribution to the (1) H spectrum at 3 T. Copyright © 2013 John Wiley & Sons, Ltd.

RecA-mediated annealing of single-stranded DNA and its relation to the mechanism of homologous recombination.

We demonstrate that RecA protein can mediate annealing of complementary DNA strands in vitro by at least two different mechanisms. The first annealing mechanism predominates under conditions where RecA protein causes coaggregation of single-stranded DNA (ssDNA) molecules and where RecA-free ssDNA stretches are present on both reaction partners. Under these conditions annealing can take place between locally concentrated protein-free complementary sequences. Other DNA aggregating agents like histone H1 or ethanol stimulate annealing by the same mechanism. The second mechanism of RecA-mediated annealing of complementary DNA strands is best manifested when preformed saturated RecA-ssDNA complexes interact with protein-free ssDNA. In this case, annealing can occur between the ssDNA strand resident in the complex and the ssDNA strand that interacts with the preformed RecA-ssDNA complex. Here, the action of RecA protein reflects its specific recombination promoting mechanism. This mechanism enables DNA molecules resident in the presynaptic RecA-DNA complexes to be exposed for hydrogen bond formation with DNA molecules contacting the presynaptic RecA-DNA filament.

Estimation of dynamic latent variable models using simulated nonparametric moments

Abstract. Given a model that can be simulated, conditional moments at a trial parameter value can be calculated with high accuracy by applying kernel smoothing methods to a long simulation. With such conditional moments in hand, standard method of moments techniques can be used to estimate the parameter. Because conditional moments are calculated using kernel smoothing rather than simple averaging, it is not necessary that the model be simulable subject to the conditioning information that is used to define the moment conditions. For this reason, the proposed estimator is applicable to general dynamic latent variable models. It is shown that as the number of simulations diverges, the estimator is consistent and a higher-order expansion reveals the stochastic difference between the infeasible GMM estimator based on the same moment conditions and the simulated version. In particular, we show how to adjust standard errors to account for the simulations. Monte Carlo results show how the estimator may be applied to a range of dynamic latent variable (DLV) models, and that it performs well in comparison to several other estimators that have been proposed for DLV models.

Visualization of recombination intermediates produced by RAD52-mediated single-strand annealing.

Double-strand breaks (DSBs) occur frequently during DNA replication. They are also caused by ionizing radiation, chemical damage or as part of the series of programmed events that occur during meiosis. In yeast, DSB repair requires RAD52, a protein that plays a critical role in homologous recombination. Here we describe the actions of human RAD52 protein in a model system for single-strand annealing (SSA) using tailed (i.e. exonuclease resected) duplex DNA molecules. Purified human RAD52 protein binds resected DSBs and promotes associations between complementary DNA termini. Heteroduplex intermediates of these recombination reactions have been visualized by electron microscopy, revealing the specific binding of multiple rings of RAD52 to the resected termini and the formation of large protein complexes at heteroduplex joints formed by RAD52-mediated annealing.

Les TIC a l'ensenyament de la modelització matemàtica en Ciències Econòmiques i en Ciències Experimentals

Aquest projecte proposa materials didàctics per a un nou plantejament de les assignatures de Matemàtiques dels primers cursos de Ciències Empresarials i d'Enginyeria Tècnica, més acord amb el procés de convergència europea, basat en la realització de projectes que anomenem “Tallers de Modelització Matemàtica” (TMM) en els quals: (1) Els alumnes parteixen de situacions i problemes reals per als quals han de construir per sí mateixos els models matemàtics més adients i, a partir de la manipulació adequada d’aquests models, poden obtenir la informació necessària per donar-los resposta. (2) El treball de construcció, experimentació i avaluació dels models es realitza amb el suport de la calculadora simbòlica Wiris i del full de càlcul Excel com a instruments “normalitzats” del treball matemàtic d’estudiants i professors. (3) S’adapten els programes de les assignatures de matemàtiques de primer curs per tal de poder-les associar a un petit nombre de Tallers que parteixen de situacions adaptades a cada titulació. L’assignatura de Matemàtiques per a les Ciències Empresarials s’articula entorn de dos tallers independents: “Matrius de transició” pel que fa a l’àlgebra lineal i “Previsió de vendes” per a la modelització funcional en una variable. L’assignatura de Matemàtiques per a l’Enginyeria s’articula entorn d’un únic taller, “Models de poblacions”, que abasta la majoria de continguts del curs: successions i models funcionals en una variable, àlgebra lineal i equacions diferencials. Un conjunt d’exercicis interactius basats en la calculadora simbòlica WIRIS (Wiris-player) serveix de suport per al treball tècnic imprescindible per al desenvolupament de les dues assignatures. L’experimentació d’aquests tallers durant 2 cursos consecutius (2006/07 i 2007/08) en dues universitats catalanes (URL i UAB) ha posat en evidència tant els innegables avantatges del nou dispositiu docent per a l’aprenentatge dels estudiants, així com les restriccions institucionals que actualment dificulten la seva gestió i difusió.

Aula matemàtica, 2a. part. : un projecte per a la millora de l'aprenentatge de les matemàtiques a la UAB

El projecte Aula Matemàtica consta de dues parts. 1. Elaborar un material d'autoaprenentatge en suport digital que cobreixi tots els temes de Matemàtiques de 1r. curs de les carreres de Ciències (Biologia, Química, etc.) i les Enginyeries. Aquest material, accessible des de qualsevol ordinador connectat a Internet, és una base de dades de problemes que els alumnes poden utilitzar per a treballar el temes explicats a classe, o be per cobrir deficiències a la seva formació pre-universitària. Al mateix temps, es poden realitzar exàmens, i els alumnes poden practicar amb els problemes d'examen. 2. Durant unes hores cada dia, oferir una (o diverses) aules d'informàtica al campus de la UAB amb presència de personal de suport (professors, o becaris de darrers cursos de matemàtiques o doctorat) per tal que els alumnes que vulguin (o necessitin) puguin practicar amb ajuda, i consultat els dubtes que tinguin. En la fase actual del projecte s’han fet les següents actuacions: 1. S’ha obert una aula d’informàtica amb suport de becaris a la facultat de Ciències, on a més de practicar els alumnes, s’han efectuat exàmens. 2. S’ha treballat en el programa per tal de fer-lo més amigable. 3. S’ha ampliat la base de problemes fins a 1450, i cobrir totes les assignatures de Matemàtiques i Estadística de 1r. curs de la facultat de Ciències i l’Escola Tècnica Superior d’Enginyeries. 4. S’ha començat a treballar per a la utilització del programa a Secundària. 5. S’han fet avanços molt importants per tal d’incorporar problemes amb resposta oberta. 6. El programa és accessible des de qualsevol ordenador amb Internet.

Pla de millora de la docència del Departament de Matemàtica Econòmica, Financera i Actuarial

La finalitat del projecte (bianual 2007-09) era aconseguir una millora de la docència que imparteix el Departament de Matemàtica Econòmica, Financera i Actuarial. La nostra tasca principal ha consistit en obtenir uns indicadors que ens permetessin conèixer millor el nostre alumnat, per tal de tenir la màxima informació a l'hora de plantejar la revisió global que representa la implantació dels nous graus d’acord amb les directrius del procés de Convergència Europea. En aquest projecte han participat tots els coordinadors de les assignatures obligatòries del Departament i els tres Grups d’Innovació Docent formats per membres del Departament. S’han analitzat les dades de les assignatures des del curs 2000-01 fins 2006-07 per tal de tenir informació sobre l’eficàcia de cursar les assignatures d’Introducció a les Matemàtiques i la seva incidència en els aprovats a Matemàtiques I i II . També s’han estudiat dades sobre el col·lectiu de repetidors. Com a resultat d’aquest estudi i de les enquestes que s’han fet, s’han redactat dos articles: “Propuesta de mejora de la actuación docente a partir de las características del alumnado de primer curso de Matemáticas en la Facultad de Economía y Empresa de la Universidad de Barcelona” y “Estudio del perfil del alumnado de primer curso en la Facultad de Economía y Empresa de la Universidad de Barcelona” que s’han presentat a dos congressos d’Innovació Docent (Burgos, setembre-2009 i Vigo, juliol-2009).

Aula Matemàtica, 3a part : un projecte per a la millora de l'aprenentatge de les Matemàtiques a la UAB

Aquest projecte és continuació dels projectes "Aula Matemàtica, un projecte per a la millora de l'aprenentatge de les Matemàtiques a la UAB", primera i segona part, Ref 2003MQD 00030 i Ref 2006MQD00072, els quals han permès identificar els problemes i oferir als estudiants de primer curs d'algunes titulacions pilot de Ciències de la UAB una plataforma d'autoaprenentatge que han valorat positivament. Es tracta d'una base de dades de problemes de resposta tancada, accessible per internet, que permet als estudiants practicar pel seu compte, autoevaluar-se i també al seu professor posar-los-hi un examen i controlar el temps de pràctica dels estudiants. L'aprenentatge de les Matemàtiques requereix l'automatització de certes tècniques de caire, per exemple, manipulatiu, per a l'adquisició de la qual és imprescindible un treball repetitiu d'entrenament de l'estudiant. Es tracta de proporcionar material interactiu que permeti aquest entrenament, al ritme de l’estudiant, de manera autònoma, no presencial i atractiva per a les noves generacions; però alhora oferir suport presencial quan sigui necessari. L'enorme diversificació observada en la formació inicial dels estudiants, amb la convivència de diferents vies de batxillerat en moltes titulacions de ciències, provoca una dificultat d'adaptació de les assignatures de primer curs. Es requereix per tant una major tutorització dels estudiants i oferta d'eines i material complementari per al treball individual. El projecte actual té com a objectius l'elaboració de més material i la classificació d'aquest per permetre l'adaptació de la plataforma a un major nombre d'assignatures i la millora de l'accessibilitat i la gestió d'aquesta plataforma.

Oncology clinicians' defenses and adherence to communication skills training with simulated patients: an exploratory study.

The aim of this exploratory study was to assess the impact of clinicians' defense mechanisms-defined as self-protective psychological mechanisms triggered by the affective load of the encounter with the patient-on adherence to a communication skills training (CST). The population consisted of oncology clinicians (N = 31) who participated in a CST. An interview with simulated cancer patients was recorded prior and 6 months after CST. Defenses were measured before and after CST and correlated with a prototype of an ideally conducted interview based on the criteria of CST-teachers. Clinicians who used more adaptive defense mechanisms showed better adherence to communication skills after CST than clinicians with less adaptive defenses (F(1, 29) = 5.26, p = 0.03, d = 0.42). Improvement in communication skills after CST seems to depend on the initial levels of defenses of the clinician prior to CST. Implications for practice and training are discussed. Communication has been recognized as a central element of cancer care [1]. Ineffective communication may contribute to patients' confusion, uncertainty, and increased difficulty in asking questions, expressing feelings, and understanding information [2, 3], and may also contribute to clinicians' lack of job satisfaction and emotional burnout [4]. Therefore, communication skills trainings (CST) for oncology clinicians have been widely developed over the last decade. These trainings should increase the skills of clinicians to respond to the patient's needs, and enhance an adequate encounter with the patient with efficient exchange of information [5]. While CSTs show a great diversity with regard to their pedagogic approaches [6, 7], the main elements of CST consist of (1) role play between participants, (2) analysis of videotaped interviews with simulated patients, and (3) interactive case discussion provided by participants. As recently stated in a consensus paper [8], CSTs need to be taught in small groups (up to 10-12 participants) and have a minimal duration of at least 3 days in order to be effective. Several systematic reviews evaluated the impact of CST on clinicians' communication skills [9-11]. Effectiveness of CST can be assessed by two main approaches: participant-based and patient-based outcomes. Measures can be self-reported, but, according to Gysels et al. [10], behavioral assessment of patient-physician interviews [12] is the most objective and reliable method for measuring change after training. Based on 22 studies on participants' outcomes, Merckaert et al. [9] reported an increase of communication skills and participants' satisfaction with training and changes in attitudes and beliefs. The evaluation of CST remains a challenging task and variables mediating skills improvement remain unidentified. We recently thus conducted a study evaluating the impact of CST on clinicians' defenses by comparing the evolution of defenses of clinicians participating in CST with defenses of a control group without training [13]. Defenses are unconscious psychological processes which protect from anxiety or distress. Therefore, they contribute to the individual's adaptation to stress [14]. Perry refers to the term "defensive functioning" to indicate the degree of adaptation linked to the use of a range of specific defenses by an individual, ranging from low defensive functioning when he or she tends to use generally less adaptive defenses (such as projection, denial, or acting out) to high defensive functioning when he or she tends to use generally more adaptive defenses (such as altruism, intellectualization, or introspection) [15, 16]. Although several authors have addressed the emotional difficulties of oncology clinicians when facing patients and their need to preserve themselves [7, 17, 18], no research has yet been conducted on the defenses of clinicians. For example, repeated use of less adaptive defenses, such as denial, may allow the clinician to avoid or reduce distress, but it also diminishes his ability to respond to the patient's emotions, to identify and to respond adequately to his needs, and to foster the therapeutic alliance. Results of the above-mentioned study [13] showed two groups of clinicians: one with a higher defensive functioning and one with a lower defensive functioning prior to CST. After the training, a difference in defensive functioning between clinicians who participated in CST and clinicians of the control group was only showed for clinicians with a higher defensive functioning. Some clinicians may therefore be more responsive to CST than others. To further address this issue, the present study aimed to evaluate the relationship between the level of adherence to an "ideally conducted interview", as defined by the teachers of the CST, and the level of the clinician' defensive functioning. We hypothesized that, after CST, clinicians with a higher defensive functioning show a greater adherence to the "ideally conducted interview" than clinicians with a lower defensive functioning.

Performance of an ICU ventilator and two turbin-based ventilators dedicated to non invasive ventilation (NIV) in simulated high inspiratory effort and rate: a NIV-bench-study.

INTRODUCTION. The role of turbine-based NIV ventilators (TBV) versus ICU ventilators with NIV mode activated (ICUV) to deliver NIV in case of severe respiratory failure remains debated. OBJECTIVES. To compare the response time and pressurization capacity of TBV and ICUV during simulated NIV with normal and increased respiratory demand, in condition of normal and obstructive respiratory mechanics. METHODS. In a two-chamber lung model, a ventilator simulated normal (P0.1 = 2 mbar, respiratory rate RR = 15/min) or increased (P0.1 = 6 mbar, RR = 25/min) respiratory demand. NIV was simulated by connecting the lung model (compliance 100 ml/mbar; resistance 5 or 20 l/mbar) to a dummy head equipped with a naso-buccal mask. Connections allowed intentional leaks (29 ± 5 % of insufflated volume). Ventilators to test: Servo-i (Maquet), V60 and Vision (Philips Respironics) were connected via a standard circuit to the mask. Applied pressure support levels (PSL) were 7 mbar for normal and 14 mbar for increased demand. Airway pressure and flow were measured in the ventilator circuit and in the simulated airway. Ventilator performance was assessed by determining trigger delay (Td, ms), pressure time product at 300 ms (PTP300, mbar s) and inspiratory tidal volume (VT, ml) and compared by three-way ANOVA for the effect of inspiratory effort, resistance and the ventilator. Differences between ventilators for each condition were tested by oneway ANOVA and contrast (JMP 8.0.1, p\0.05). RESULTS. Inspiratory demand and resistance had a significant effect throughout all comparisons. Ventilator data figure in Table 1 (normal demand) and 2 (increased demand): (a) different from Servo-i, (b) different from V60.CONCLUSION. In this NIV bench study, with leaks, trigger delay was shorter for TBV with normal respiratory demand. By contrast, it was shorter for ICUV when respiratory demand was high. ICUV afforded better pressurization (PTP 300) with increased demand and PSL, particularly with increased resistance. TBV provided a higher inspiratory VT (i.e., downstream from the leaks) with normal demand, and a significantly (although minimally) lower VT with increased demand and PSL.

Desarrollo de un sistema de clasificación de recursos electrónicos en el ámbito de la lógica matemática

El presente trabajo define una taxonomía para la clasificación de recursos digitales del ámbito de la lógica tradicional, y más concretamente los recursos que se podrían generar en el ámbito de la asignatura de Lógica Matemática del plan de estudios de las titulaciones de Ingeniería Técnica de Gestión y de Sistemas impartidas en la Universitat Oberta de Catalunya (UOC).

Intrinsic test of independence in contingency tables

A condition needed for testing nested hypotheses from a Bayesianviewpoint is that the prior for the alternative model concentratesmass around the small, or null, model. For testing independencein contingency tables, the intrinsic priors satisfy this requirement.Further, the degree of concentration of the priors is controlled bya discrete parameter m, the training sample size, which plays animportant role in the resulting answer regardless of the samplesize.In this paper we study robustness of the tests of independencein contingency tables with respect to the intrinsic priors withdifferent degree of concentration around the null, and comparewith other “robust” results by Good and Crook. Consistency ofthe intrinsic Bayesian tests is established.We also discuss conditioning issues and sampling schemes,and argue that conditioning should be on either one margin orthe table total, but not on both margins.Examples using real are simulated data are given