Anharmonicity contributions to the vibrational second hyperpolarizability of conjugated oligomers

Restricted Hartree-Fock 6-31G calculations of electrical and mechanical anharmonicity contributions to the longitudinal vibrational second hyperpolarizability have been carried out for eight homologous series of conjugated oligomers - polyacetylene, polyyne, polydiacetylene, polybutatriene, polycumulene, polysilane, polymethineimine, and polypyrrole. To draw conclusions about the limiting infinite polymer behavior, chains containing up to 12 heavy atoms along the conjugated backbone were considered. In general, the vibrational hyperpolarizabilities are substantial in comparison with their static electronic counterparts for the dc-Kerr and degenerate four-wave mixing processes (as well as for static fields) but not for electric field-induced second harmonic generation or third harmonic generation. Anharmonicity terms due to nuclear relaxation are important for the dc-Kerr effect (and for the static hyperpolarizability) in the σ-conjugated polymer, polysilane, as well as the nonplanar π systems polymethineimine and polypyrrole. Restricting polypyrrole to be planar, as it is in the crystal phase, causes these anharmonic terms to become negligible. When the same restriction is applied to polymethineimine the effect is reduced but remains quantitatively significant due to the first-order contribution. We conclude that anharmonicity associated with nuclear relaxation can be ignored, for semiquantitative purposes, in planar π-conjugated polymers. The role of zero-point vibrational averaging remains to be evaluated

The curvature of the conical intersection seam: an approximate second-order analysis

We present a method for analyzing the curvature (second derivatives) of the conical intersection hyperline at an optimized critical point. Our method uses the projected Hessians of the degenerate states after elimination of the two branching space coordinates, and is equivalent to a frequency calculation on a single Born-Oppenheimer potential-energy surface. Based on the projected Hessians, we develop an equation for the energy as a function of a set of curvilinear coordinates where the degeneracy is preserved to second order (i.e., the conical intersection hyperline). The curvature of the potential-energy surface in these coordinates is the curvature of the conical intersection hyperline itself, and thus determines whether one has a minimum or saddle point on the hyperline. The equation used to classify optimized conical intersection points depends in a simple way on the first- and second-order degeneracy splittings calculated at these points. As an example, for fulvene, we show that the two optimized conical intersection points of C2v symmetry are saddle points on the intersection hyperline. Accordingly, there are further intersection points of lower energy, and one of C2 symmetry - presented here for the first time - is found to be the global minimum in the intersection space

Second-order Møller-Plesset perturbation theory without basis set superposition error : II : open-shell systems

The basis set superposition error-free second-order MØller-Plesset perturbation theory of intermolecular interactions was studied. The difficulties of the counterpoise (CP) correction in open-shell systems were also discussed. The calculations were performed by a program which was used for testing the new variants of the theory. It was shown that the CP correction for the diabatic surfaces should be preferred to the adiabatic ones

Polítiques, pràctiques i estratègies d'inserció: una mirada des de les trajectòries de les dones immigrades

Aquesta recerca, amb l’objectiu general de conèixer i analitzar els processos d’inserció al mercat laboral, les estratègies i pràctiques d’inserció, i els àmbits d’ocupació de les dones immigrades en la societat de recepció, es va plantejar com a finalitat proposar línies d'actuació i pràctiques d'atenció vers aquest col•lectiu. Sota l’eix 1 del Pacte Nacional, apunta a garantir la igualtat de drets i l’accés al mercat laboral de les persones, des de la tranversalitat del gènere. Mitjançant l’aplicació d'entrevistes semiestructurades per tal de construir "trajectòries d’immigració" de dones, i obtenir una mirada sociohistòrica i dinàmica del procés de d’inserció laboral a la societat de recepció, es va portar a terme la recerca amb la participació de 17 dones immigrades al territori català. Entre els resultats, cal destacar que: en quant als relats d’origen destaca la diversitat de motius de la immigració, posant en qüestió les tesis purament economicistes, i en relació amb les polítiques i pràctiques d’inserció laboral, podem confirmar que els esforços dels recursos d’atenció tendeixen a encertar a les dones en els nínxols laborals més precaritzats, i sobre tot generitzats. Per altre banda, l’estudi ens ha permet apropar-nos a les estratègies que fan servir les dones per a sortejar les limitacions, sobre tot legals, que es troben a la societat de recepció. Aquestes accions ens permeten analitzar l’agència de les dones immigrades i la importància de les xarxes socials i de la participació, per a una inserció sociolaboral més plena. A més de les conclusions i recomanacions contingudes en aquest document, s'ha elaborat un material didàctic que es composa de: 1. Documental "Per compte aliè" en el qual hi ha les històries d'inserció de 5 dones i; 2. Guia de 12 tallers de treball com a proposta d’intervenció, destinats als col•lectius i serveis que treballen per a la inserció.

Economic crisis and recovery: changes in second birth rates within occupational classes and educational groups

This study assesses the decline in second birth rates for men and women across different skill levels in transitional Russia. Changes within educational groups and occupational classes are observed over three distinct time periods: the Soviet era, economic crisis, and economic recovery. The most remarkable finding is the similarity in the extent second birth rates declined within educational groups and occupational classes during the economic crisis. Although further decline occurred in the recovery period, more variation emerged across groups.

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 development of intercultural awareness and changes of beliefs: the effects of studying abroad on learners of English as a second language

The present study examines the development of interculturality and changes of beliefs, by analyzing 106 compositions produced by 53 advanced level university students of translation studies at a university in Spain before and shortly after a stay-abroad (SA) period. The study draws on data collected at two different times: before (T1) and after the SA (T3). In addition, we compared the results with the writings produced by a control group of 10 native English speakers on SA too. Data were collected by means of a composition which tried to elicit the learners’ opinion about cultural habits maintenance. The results reveal significant changes between T1 and T3 in the degree of better attitudes and intercultural acquisition.

Calibration of stochastic volatility models via second order approximation: the Heston model case

Using a suitable Hull and White type formula we develop a methodology to obtain asecond order approximation to the implied volatility for very short maturities. Using thisapproximation we accurately calibrate the full set of parameters of the Heston model. Oneof the reasons that makes our calibration for short maturities so accurate is that we alsotake into account the term-structure for large maturities. We may say that calibration isnot "memoryless", in the sense that the option's behavior far away from maturity doesinfluence calibration when the option gets close to expiration. Our results provide a wayto perform a quick calibration of a closed-form approximation to vanilla options that canthen be used to price exotic derivatives. The methodology is simple, accurate, fast, andit requires a minimal computational cost.

Insider Trading and Real Investment

In this paper I analyze the effects of insider trading on real investmentand the insurance role of financial markets. There is a single entrepreneurwho, at a first stage, chooses the level of investment in a risky business.At the second stage, an asset with random payoff is issued and then the entrepreneurreceives some privileged information on the likely realization of productionreturn. At the third stage, trading occurs on the asset market, where theentrepreneur faces the aggregate demand coming from a continuum of rationaluniformed traders and some noise traders. I compare the equilibrium withinsider trading (when the entrepreneur trades on her inside information in theasset market) with the equilibrium in the same market without insider trading. Ifind that permitting insider trading tends to decrease the level of realinvestment. Moreover, the asset market is thinner and the entrepreneur's netsupply of the asset and the hedge ratio are lower, although the asset priceis more informative and volatile.

Multi-sample analysis of moment-structures: Asymptotic validity of inferences based on second-order moments

In moment structure analysis with nonnormal data, asymptotic valid inferences require the computation of a consistent (under general distributional assumptions) estimate of the matrix $\Gamma$ of asymptotic variances of sample second--order moments. Such a consistent estimate involves the fourth--order sample moments of the data. In practice, the use of fourth--order moments leads to computational burden and lack of robustness against small samples. In this paper we show that, under certain assumptions, correct asymptotic inferences can be attained when $\Gamma$ is replaced by a matrix $\Omega$ that involves only the second--order moments of the data. The present paper extends to the context of multi--sample analysis of second--order moment structures, results derived in the context of (simple--sample) covariance structure analysis (Satorra and Bentler, 1990). The results apply to a variety of estimation methods and general type of statistics. An example involving a test of equality of means under covariance restrictions illustrates theoretical aspects of the paper.

Optimal second-degree price discrimination and arbitrage: On the role of asymetric information among buyers

The traditional theory of monopolistic screening tackles individualself-selection but does not address the possibility that buyers couldform a coalition to coordinate their purchases and to reallocate thegoods. In this paper, we design the optimal sale mechanism which takesinto account both individual and coalition incentive compatibilityfocusing on the role of asymmetric information among buyers. We showthat when a coalition of buyers is formed under asymmetric information,the monopolist can do as well as when there is no coalition. Although inthe optimal sale mechanism marginal rates of substitution are notequalized across buyers (hence there exists room for arbitrage), theyfail to realize the gains from arbitrage because of the transaction costsin coalition formation generated by asymmetric information.

World population growth and fertility patterns, 1960-2000. A simple model explaining the evolution of world's fertility during the second half of the 20th Century

In this paper we attempt to describe the general reasons behind the world populationexplosion in the 20th century. The size of the population at the end of the century inquestion, deemed excessive by some, was a consequence of a dramatic improvementin life expectancies, attributable, in turn, to scientific innovation, the circulation ofinformation and economic growth. Nevertheless, fertility is a variable that plays acrucial role in differences in demographic growth. We identify infant mortality, femaleeducation levels and racial identity as important exogenous variables affecting fertility.It is estimated that in poor countries one additional year of primary schooling forwomen leads to 0.614 child less per couple on average (worldwide). While it may bepossible to identify a global tendency towards convergence in demographic trends,particular attention should be paid to the case of Africa, not only due to its differentdemographic patterns, but also because much of the continent's population has yet toexperience improvement in quality of life generally enjoyed across the rest of theplanet.

Insurance and safety after September 11, 2001: Coming to grips with the costs and threats of terrorism

This chapter, originally written as a consequence of the terrorist attacksof September 11, 2001, provides an elementary, everyday introduction tothe concepts of risk and insurance. Conceptually, risk has two dimensions:a potential loss, and the chance of that loss being realized. People can,however, transfer risk to insurance companies against the payment ofso-called premiums. In practice, however, one needs accurate assessmentsof both losses and probabilities to judge whether premiums are appropriate.For many risks, this poses little problem (e.g., life insurance); however,it is difficult to assess risks of many other kinds of events such as actsof terrorism. It is emphasized, that through evolution and learning, peopleare able to handle many of the common risks that they face in life. Butwhen people lack experience (e.g., new technologies, threats of terrorism),risk can only be assessed through imagination. Not surprisingly, insurancecompanies demand high prices when risks are poorly understood. In particular,the cost of insurance against possible acts of terrorism soared afterSeptember 11. How should people approach risk after the events of that day?Clearly, the world needs to protect itself from the acts of terrorists andother disturbed individuals. However, it is also important to address the root causes of such antisocial movements. It is, therefore, suggested thatprograms addressed at combatting ignorance, prejudice, and socialinequalities may be more effective premiums for reducing the risk ofterrosrtism than has been recognized to date.

Motivation and content Language Integrated Learning : an impulse for Second Language Teaching

“Estudiantes motivados producen profesores motivados y viceversa” (Lesley Denham)La cita refleja el efecto recíproco que tiene el comportamiento del profesor en el compromiso de los estudiantes a lo largo del año y viceversa. Es sorprendente como, destacando las fortalezas de cada estudiante en lugar de sus debilidades, nunca comparándolos entre ellos sino con su propio rendimiento, puede despertar una motivación intrínseca en el estudiante, y una merecida satisfacción personal para el profesor.Sin embargo, no existen botones motivacionales mágicos que podamos pulsar y hacer que el alumno quiera aprender. Como profesores, tomar la iniciativa será crucial: dar a nuestros estudiantes el espacio suficiente para experimentar, realzar su autonomía, e intuir las respuestas a través de un proceso inductivo. En definitiva, hacerles protagonistas de su proceso de aprendizaje.Incluir AICLE en la clase de inglés es una metodología que nos ayudará a conseguirlo. Los estudiantes asocian AICLE con algo interesante y divertido, diferente a las sesiones teóricas. Como resultado, al utilizar la lengua, lo hacen movidos por sus sentimientos, aprendiendo de forma implícita.“Estudiants motivats produeixen professors motivats i viceversa” (Lesley Denham)La cita reflecteix l'efecte recíproc que té el comportament del professor en el compromís dels estudiants al llarg de l'any i viceversa. És sorprenent com, destacant les fortaleses de cada estudiant en lloc de les seves debilitats, mai comparant-los entre ells sinó amb el seu propi rendiment, pot despertar una motivació intrínseca a l'estudiant, i una merescuda satisfacció personal per al professor.No obstant això, no existeixen botons motivacionals màgics que puguem prémer i fer que l'alumne vulgui aprendre. Com a professors, prendre la iniciativa serà crucial: donar als nostres estudiants l'espai suficient per experimentar, realçar la seva autonomia, i intuir les respostes a través d'un procés inductiu. En definitiva, fer-los protagonistes del seu procés d'aprenentatge.Incloure AICLE en la classe d'anglès és una metodologia que ens ajudarà a aconseguir-ho. Els estudiants consideren AICLE interessant i divertit, diferent a les sessions teòriques. Com a resultat, en utilitzar la llengua, ho fan moguts pels seus sentiments, aprenent de forma implícita.