Performance Analysis of Two Quantum Reaction Dynamics Codes: Time-Dependent and Time-Independent Strategies

The computer simulation of reaction dynamics has nowadays reached a remarkable degree of accuracy. Triatomic elementary reactions are rigorously studied with great detail on a straightforward basis using a considerable variety of Quantum Dynamics computational tools available to the scientific community. In our contribution we compare the performance of two quantum scattering codes in the computation of reaction cross sections of a triatomic benchmark reaction such as the gas phase reaction Ne + H2+ %12. NeH++ H. The computational codes are selected as representative of time-dependent (Real Wave Packet [ ]) and time-independent (ABC [ ]) methodologies. The main conclusion to be drawn from our study is that both strategies are, to a great extent, not competing but rather complementary. While time-dependent calculations advantages with respect to the energy range that can be covered in a single simulation, time-independent approaches offer much more detailed information from each single energy calculation. Further details such as the calculation of reactivity at very low collision energies or the computational effort related to account for the Coriolis couplings are analyzed in this paper.

Performance Analysis of Two Quantum Reaction Dynamics Codes: Time-Dependent and Time-Independent Strategies

The computer simulation of reaction dynamics has nowadays reached a remarkable degree of accuracy. Triatomic elementary reactions are rigorously studied with great detail on a straightforward basis using a considerable variety of Quantum Dynamics computational tools available to the scientific community. In our contribution we compare the performance of two quantum scattering codes in the computation of reaction cross sections of a triatomic benchmark reaction such as the gas phase reaction Ne + H2+ %12. NeH++ H. The computational codes are selected as representative of time-dependent (Real Wave Packet [ ]) and time-independent (ABC [ ]) methodologies. The main conclusion to be drawn from our study is that both strategies are, to a great extent, not competing but rather complementary. While time-dependent calculations advantages with respect to the energy range that can be covered in a single simulation, time-independent approaches offer much more detailed information from each single energy calculation. Further details such as the calculation of reactivity at very low collision energies or the computational effort related to account for the Coriolis couplings are analyzed in this paper.

┴N as an Abstract Elementary Class

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Screening of highly modular sugar-based ligand libraries in the enantioselective C-C coupling reactions

Projecte de recerca elaborat a partir d’una estada a la University of Nottingham, Gran Bretanya, entre març i abril del 2007. Aquest treball s’ha centrat en l’aplicació de compostos derivats de la D-(+)-glucosa, de la D-(+)-fructosa i la D-galactosa com a lligands de catalitzadors homogenis quirals en dos reaccions asimètriques: addició 1,2 a aldehids catalitzada per níquel i addició 1,4 conjugada catalitzada per coure.(veure figura adjunta al final del document). En primer lloc, s’ha estudiat l’aplicació dels compostos L1-L6 a les reaccions d’addició 1,2 a aldehids catalitzades per níquel. S’ha observat que la selectivitat del procés depèn principalment del grup funcional unit a l’esquelet del lligand, de les propietats estèriques del substituent en la funció oxazolina i de l’estructura del substrat. S’ha obtingut fins a un 59% d’excés enantiomèric utilitzant el precursor de catalitzador que conté el lligand L3a. En segon lloc, aquest treball descriu l’aplicació de les tres famílies de compostos (L1-L11) com a lligands en la reacció d’addició 1,4 catalitzada per coure de compostos organometàl•lics a diferents enones amb diferents propietats estèriques. L’ús de les llibreries de compostos fosfit-oxazolina (L1-L5) i fosfit-fosforamidit (L6) han proporcionat bones enantioselectivitats (fins a 80%) en l’addició de reactius de trialquilalumini a diferents enones. En canvi, la llibreria de compostos monofosfit (L7-L11) ha mostrat bones activitats però enantioselectivitats fins a 57%.

Divergent Reactions to Globalization: Labor Unions and the Nafta and the EU Enlargement Process

The 1990s witnessed the launching of two ambitious trade regionalization plans, the Nafta and EU enlargement to Central and Eastern Europe. In contrast to previous projects for the creation or expansion of regional trade blocs, these two projects concerned states at dramatically different levels of economic development: The Nafta involved the very wealthy economies of Canada and the USA and the significantly poorer economy of Mexico, whereas EU enlargement involved the very wealthy economy of the 15 member-state European Union and the significantly poorer economies of former Communist states in Central and Eastern Europe. Ultimately, the Nafta and EU enlargement are responses to the challenges of globalization. Paradoxically, however, they have been met with radically different societal reactions in the wealthy partners that participated in the launching of these processes. This paper focuses on the reaction by labor unions on both sides of the Atlantic. I conclude that while labor relations and welfare institutions constrained the trade policy choices made by labor unions in the United States and Europe, they do not tell the whole story. It would seem that United States labor unions were more sensitive to the potential risks for workers associated to the liberalization of trade than were their European counterparts.

Teachers' reactions on students' responses: essential for an adequate task monitoring

This research project analyzes the reactions the teacher has on students' responses. Different techniques as discourse markers, types of questions and repair sequences are taken into account, but the author puts a special emphasis on non-verbal communication. To be aware of all these ways of reacting in a class interaction is essential for an adequate task monitoring

On absoluteness of categoricity in abstract elementary classes

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Potential isomorphism of elementary substructures of a strictly stable homogeneous model

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Temperamental Dimension and Anxiety Problems in a Clinical Sample of Three- to Six-year old Children: A Study of Variables

In the last few years, many researchers have studied the presence of common dimensions of temperament in subjects with symptoms of anxiety. The aim of this study is to examine the association between temperamental dimensions (high negative affect and activity level) and anxiety problems in clinicalpreschool children. A total of 38 children, ages 3 to 6 years, from the Infant and Adolescent Mental Health Center of Girona and the Center of Diagnosis and Early Attention of Sabadell and Olot were evaluated by parents and psychologists. Their parents completed several screening scales and, subsequently, clinical child psychopathology professionals carried out diagnostic interviews with children from the sample who presented signs of anxiety. Findings showed that children with high levels of negative affect and low activity level have pronounced symptoms of anxiety. However, children with anxiety disorders do not present different temperament styles from their peers without these pathologies

Intergovernmental Transfers and Elementary Education: Quasi-Experimental Evidence from Brazil

Whether providing additional resources to local communities leads to improved public services and better outcomes more generally, given existing management capacity and incentive and accountability structures, is an unresolved yet important question for public policy. This paper uses a regression-discontinuity design to evaluate the effect of unrestricted fiscal transfers on local spending (including on education), schooling and learning in Brazil. Results show that transfers increase local public spending almost one for one with no evidence of crowding out own revenue or other revenue sources. Extra per capita transfers of 1000 Reais lead to about 0.42 additional years of elementary schooling and student literacy rates increase by about 5.6 percentage points on average. Part of this effect arises through higher teacher-student ratios in municipal elementary school systems. Results also suggest that additional resources have stronger effects in more rural and less developed parts of Brazil.

Emotion and reason in everyday risk perception

Although research has documented the importance of emotion in risk perception, little is knownabout its prevalence in everyday life. Using the Experience Sampling Method, 94 part-timestudents were prompted at random via cellular telephones to report on mood state and threeemotions and to assess risk on thirty occasions during their working hours. The emotions valence, arousal, and dominance were measured using self-assessment manikins (Bradley &Lang, 1994). Hierarchical linear models (HLM) revealed that mood state and emotions explainedsignificant variance in risk perception. In addition, valence and arousal accounted for varianceover and above reason (measured by severity and possibility of risks). Six risks were reassessedin a post-experimental session and found to be lower than their real-time counterparts.The study demonstrates the feasibility and value of collecting representative samples of data withsimple technology. Evidence for the statistical consistency of the HLM estimates is provided inan Appendix.

Predictive factors in the long term outcome in gastro-oesophageal reflux disease: six years follow up of 107 patients

There is little information concerning the long term outcome of patients with gastro-oesophageal reflux disease (GORD). Thus 109 patients with reflux symptoms (33 with erosive oesophagitis) with a diagnosis of GORD after clinical evaluation and oesophageal testing were studied. All patients were treated with a stepwise approach: (a) lifestyle changes were suggested aimed at reducing reflux and antacids and the prokinetic agent domperidone were prescribed; (b) H2 blockers were added after two months when symptoms persisted; (c) anti-reflux surgery was indicated when there was no response to (b). Treatment was adjusted to maintain clinical remission during follow up. Long term treatment need was defined as minor when conservative measures sufficed for proper control, and as major if daily H2 blockers or surgery were required. The results showed that one third of the patients each had initial therapeutic need (a), (b), and (c). Of 103 patients available for follow up at three years and 89 at six years, respective therapeutic needs were minor in 52% and 55% and major in 48% and 45%. Eighty per cent of patients in (a), 67% in (b), and 17% in (c) required only conservative measures at six years. A decreasing lower oesophageal sphincter pressure (p < 0.001), radiological reflux (p = 0.028), and erosive oesophagitis (p = 0.031), but not initial clinical scores, were independent predictors of major therapeutic need as shown by multivariate analysis. The long term outcome of GORD is better than previously perceived.

SL(3,C) elementary instanton configurations

Several SL(3,C) self-dual instanton solutions of the Yang-Mills equations are presented which have very striking properties. While one of them is regular and SU(3) inside (outside) a sphere of arbitrarily large (small) radius, another one has all the characteristics of a meron solution (in particular its topological charge is concentrated at one point) although its Pontryagin number equals one. Their continuation to Minkowski space is also studied.

Does the sun shine by p p or CNO fusion reactions?

We show that solar neutrino experiments set an upper limit of 7.8% (7.3% including the recent KamLAND measurements) to the fraction of energy that the Sun produces via the CNO fusion cycle, which is an order of magnitude improvement upon the previous limit. New experiments are required to detect CNO neutrinos corresponding to the 1.5% of the solar luminosity that the standard solar model predicts is generated by the CNO cycle.