Persistence of instanton connections in chemical reactions with time dependent rates

The evolution of a system of chemical reactions can be studied, in the eikonal approximation, by means of a Hamiltonian dynamical system. The fixed points of this dynamical system represent the different states in which the chemical system can be found, and the connections among them represent instantons or optimal paths linking these states. We study the relation between the phase portrait of the Hamiltonian system representing a set of chemical reactions with constant rates and the corresponding system when these rates vary in time. We show that the topology of the phase space is robust for small time-dependent perturbations in concrete examples and state general results when possible. This robustness allows us to apply some of the conclusions on the qualitative behavior of the autonomous system to the time-dependent situation

Recensiones [Revista de Historia Económica Año XV Otoño-Invierno 1997 n. 3 pp. 637-673]

Editada en la Fundación Empresa PúblicaDavid S. Reher. La familia en España, pasado y presenta (Por Enriqueta Camps Cura).-- Juan A. Sánchez Belén. La política fiscal en Castilla durante el reinado de Carlos V (Por Francisco Comín).-- José Marchena. Burgueses y caciques en el Cádiz de la Restauración (Por Carlos Larrinaga).-- G. Pérez Sánchez. Ser trabajador; vida y respuesta obrera (Valladolid 1875-1931) (Por Esmeralda Ballesteros Doncel).-- María Teresa Pérez Picazo. Historia de España del siglo XX (Por Antonio Escudero).-- Virginia García Acosta (coord.). Los precios de alimentos y manufacturas novohispanos (Por Juan Carlos Sola Corbacho).-- Roberto Cortés Conde. La economía argentina en el largo plazo (Por Isabel Sanz Vülarroya).-- Philip Hoffmam. Growth in a Traditional Society (Por Juan Antonio Carmona Pidal).-- Michael Huberman. Escape from the market. Negotiating work in Lancashire (Por Joan R. Roses).-- Jean-Michel Selig. Malnutrition & dévelopment économique dans l'Alsace duxix siécle (Por José Miguel Martínez Carrión).-- R. M. Hartwell. A History of the Mont Pelerin Society (Por Carlos Rodríguez Braun).-- N. Crafts and G. Toniolo. Economic growth in Europe since 1945 (Por DouglasJ. Forsyth).-- Jaime Reis. O Banco de Portugal das Origens a 1914. I Volume: Antecedentes. Fundafao. Consolidagao (1821-1857) (Por Pablo Martín Aceña)Publicad

¿El emprendedor nace o se hace? Un análisis de los determinantes del espíritu emprendedor

Aún a sabiendas de que el espíritu emprendedor juega un papel clave como motor de la innovación y del bienestar en una economía, las cuestiones acerca de porqué se crean empresas y qué factores determinan tal hecho, es un fenómeno insuficientemente estudiado. En el presente trabajo, nuestro interés se centra en reconocer los factores determinantes del espíritu emprendedor. En concreto, se valoran las percepciones de una población de 2012 estudiantes universitarios que en el curso académico 2003/2004 se encontraba en los últimos años de sus estudios y su propensión a la creación de empresas. Utilizando un análisis de regresión logística binaria, se obtienen unos resultados que confirman las relaciones esperadas en relación con los determinantes de una orientación emprendedora: los hombres, con mayor formación y un mayor número de experiencias profesionales son los que tienen una orientación más emprendedora. Asimismo, las personas con mayor deseo de independencia y autoconfianza son las más que resultan más propensas a tomar decisiones empresariales.Although the entrepreneurship is basic as innovation device or as contributor for economic welfare, we do not much about why firms are created or which factors are determinants of new ventures. This paper tries to contribute to this subject exploring the factors related to the entrepreneurial direction of students. Particularly, we select a population of 2012 undergraduate students during the 2003/2004 academic year and we measure their entrepreneurial direction and the factors that motivate it. A logistic regression allows confirming the most of suggested relationships. The students who are entrepreneurshiporiented show a higher level of education, more professional experiences and they are usually men. Other than that, the self-reliant and self-confident individuals are the most prone to create a new venture

Cambio Conceptual en los Grupos de Crecimiento Personal: Un estudio de caso [Conceptual Change in Personal Development Groups: A Case Study]

ResumenEste estudio presenta el análisis de un caso como ejemplo de la utilización del Diferencial Semántico (DS) para la evaluación de los cambios de significado y de su estructura en casos individuales en contextos psicoterapéuticos. Este trabajo supone una ampliación del estudio previo (Gil Escudero y Rodríguez Zafra, 2012) en el que se presentaron los resultados sobre la eficacia de los Grupos de Crecimiento Personal (GCP) para contribuir al cambio del significado de algunos conceptos psicológicos centrales de los participantes en estos grupos. Estos cambios de significado se consideran como indicadores de los cambios emocionales, actitudinales y cognitivos, que se producen habitualmente como resultado de la participación en estas experiencias intensivas de grupo. El análisis conjunto de los datos del caso, indica que, tras la participación en la experiencia intensiva de grupo se valora en mayor medida el Yo y se considera como más benigno, sereno, con mayor bienestar subjetivo, más fuerte y dinámico, se percibe el Grupo como más positivo al considerarlo mejor y más valioso, más comunicativo y afectivo, más fuerte y dinámico, y más íntegro y auténtico; se valora más positivamente la Vida percibiéndose como más buena y valiosa, más auténtica y con mayor bienestar. No se encontraron cambios suficientemente significativos de los promedios del conjunto de participantes en los GCP en la valoración de la Madre y el Padre. En general, se produce una mejoría general del estado de ánimo que se refleja en el aumento global de los promedios de respuesta al conjunto del DS.Abstract This study presents a case analysis as an exemplifica­tion of using the Semantic Differential (DS) for the as­sessment of the changes of meaning and its structure in individual cases in therapeutic contexts.This work entails an extension of the previous study (Gil Escudero y Ro­driguez Zafra, 2012) where results about the efficiency of Personal Development Groups (PGG) to the change of meaning of some main psychological concepts of partic­ipants in these groups were presented. These changes of meaning are considered as indicators of the emotional, attitudinal and cognitive changes that usually turn out as a result of the participation in such intensive group expe­riences. The joint analysis of the case data indicates that, after participation in the intensive group experience, the I is valued more and is considered as more benign, se­rene, with greater subjective well-being, stronger and more dynamic, the perception is perceived. Group as more positive when considering it better and more valu­able, more communicative and affective, stronger and more dynamic, and more complete and authentic; Life is valued more positively, perceiving itself as more good and valuable, more authentic and with greater well-be­ing. No sufficiently significant changes were found in the averages of the group of participants in the CPG in the evaluation of the Mother and the Father. In general, there is a general improvement in mood that is reflected in the overall increase in the average response to the DS as a whole

The amino- and carboxyl-terminal fragments of the Bacillus thuringensis Cyt1Aa toxin have differential roles on toxin oligomerization and pore formation

The Cyt toxins produced by the bacteria Bacillus thuringiensis show insecticidal activity against some insects, mainly dipteran larvae, being able to kill mosquitoes and black flies. However, they also possess a general cytolytic activity in vitro showing hemolytic activity in red blood cells. These proteins are composed of two outer layers of α-helix hairpins wrapped around a β-sheet. Regarding to their mode of action, one model proposed that the two outer layers of α-helix hairpins swing away from the β-sheet allowing insertion of β-strands into the membrane forming a pore after toxin oligomerization. The other model suggested a detergent-like mechanism of action of the toxin on the surface of the lipid bilayer. In this work we cloned the N- and C-terminal domains form Cyt1Aa and analyzed their effects in Cyt1Aa toxin action. The N-terminal domain shows a dominant negative phenotype inhibiting the in vitro hemolytic activity of Cyt1Aa in red blood cells and the in vivo insecticidal activity of Cyt1Aa against Aedes aegypti larvae. In addition, N-terminal region is able to induce aggregation of Cyt1Aa toxin in solution. Finally, Cterminal domain composed mainly of β-strands, is able to bind to the SUV liposomes, suggesting that this region of the toxin is involved in membrane interaction. Overall, our data indicate that the two isolated domains of Cyt1Aa have different roles in toxin action. The N-terminal region is involved in toxin aggregation while the C-terminal domain in the interaction of the toxin with the lipid membrane.Research was funded in part through grants from the National Institutes of Health, 1R01 AI066014, DGAPA/UNAM IN218608 and IN210208-N, CONACyT U48631-Q 478. IRdE received a José Castillejo postdoctoral grant, and a mobility grant for teaching and research staff of UPNA, Spain

Complexity analysis of spontaneous brain activity: effects of depression and antidepressant treatment

Magnetoencephalography (MEG) allows the real-time recording of neural activity and oscillatory activity in distributed neural networks. We applied a non-linear complexity analysis to resting-state neural activity as measured using whole-head MEG. Recordings were obtained from 20 unmedicated patients with major depressive disorder and 19 matched healthy controls. Subsequently, after 6 months of pharmacological treatment with the antidepressant mirtazapine 30 mg/day, patients received a second MEG scan. A measure of the complexity of neural signals, the Lempel–Ziv Complexity (LZC), was derived from the MEG time series. We found that depressed patients showed higher pre-treatment complexity values compared with controls, and that complexity values decreased after 6 months of effective pharmacological treatment, although this effect was statistically significant only in younger patients. The main treatment effect was to recover the tendency observed in controls of a positive correlation between age and complexity values. Importantly, the reduction of complexity with treatment correlated with the degree of clinical symptom remission. We suggest that LZC, a formal measure of neural activity complexity, is sensitive to the dynamic physiological changes observed in depression and may potentially offer an objective marker of depression and its remission after treatment

Reversible mechanical induction of optical activity in solutions of soft-matter nanophases

Nanophases of J-aggregates of several achiral amphiphilic porphyrins, which have thin long acicular shapes (nanoribbons), show the immediate and reversible formation of a stationary mechano-chiral state in the solution by vortex stirring, as detected by their circular dichroic signals measured by 2-modulator generallized ellipsometry. The results suggest that when a macroscopic chiral force creates supramolecular chirality, it also creates an enantiomeric excess of screw distortions, which may be detected by their excitonic absorption. An explanation on the effect of the shear flow gradients is proposed on the basis of the orientation of the rotating particles in the vortex and the size, shape, and mechanical properties of the nanoparticles

Localization of Muscle Edema and Changes on Muscle Contractility After Dry Needling of Latent Trigger Points in the Gastrocnemius Muscle

Background. Myofascial trigger points (TrPs) are hyperirritable spots within taut bands of skeletal muscles that elicit local and referred pain when stimulated. Among the variety of techniques used for treating TrPs, dry needling (DN) is the most commonly applied intervention. The physiological mechanisms underlying the effects of DN remain to be elucidated. Objective. To examine changes in skeletal muscle after DN in the area where the TrP is located. Methods. We measured in vivo changes that occur in human skeletal muscle one hour after DN over a TrP with magnetic resonance imaging (MRI) and tensiomyography. The study included 18 asymptomatic subjects with a latent TrP in one medial gastrocnemius muscle, and the contralateral leg was used as control. Results. The results showed that MRI signal intensity significantly increased one hour after the DN intervention, suggesting the presence of intramuscular edema. Tensiomyographic parameters showed higher muscle stiffness with an improvement in contraction time after DN. Conclusions. This is the first study showing intramuscular edema after TrP DN in human skeletal muscle. Future research should focus on using DN therapy in patients with active TrPs and on monitoring changes occurring at longer follow-up with imaging techniques.Fisioterapi

Hip fracture rates and bisphosphonate consumption in Spain. An ecologic study

Producción CientíficaIntroduction Bisphosphonates are used worldwide to treat osteoporosis and, thus, to prevent fractures. Though they have been proven in clinical trials to avoid some fractures, their effectiveness in reducing hip fractures is unclear. The aim of the present study was to explore the relationship between bisphosphonate use and hip fracture trends in Spain. Methods For this purpose, an ecologic study spanning 2002 to 2008 was conducted in Spain. Consumption data were obtained from the Spanish Ministry of Health and Social Policy. The number of hip fractures was obtained from hospital discharges; annual hip fracture rates were determined and standardized using the Spanish 2002 population census. A linear regression was performed between fracture rate and use of bisphosphonates; R2 and Pearson correlation coefficient were calculated. Results From 2002 to 2008, dispensed prescriptions of bisphosphonates in Spain increased from 3.28 to 17.66 DDD/1,000 inhabitants per day. In the same period, the crude hip fracture rate increased from 2.85 to 3.02 cases per 1,000 inhabitants older than 50 years; however, when age standardized rates were estimated, the rate declined from 2.85 to 2.79. Analyzed by sex, the standardized rate for men slightly increased from 1.45 to 1.48, while for women the rate significantly dropped from 4.00 to 3.91.Conclusion A small effect of bisphosphonates on hip fracture rates can not be ruled out; however, other factors might partially explain this decline. Assuming this medication was the only cause for hip fracture rate reduction, the elevated medication cost to avoid a single hip fracture makes it necessary to explore less expensive intervention

On the mechano-chiral effect of vortical flows on the dichroic spectra of 5-phenyl-10,15,20-tris(4-sulfonatophenyl)porphyrin J-aggregates

Phase-modulated ellipsometry of the J-aggregates of the title porphyrin shows that the material gives a true CD signal. This confirms that there is a real chiral transfer by mechanical forces, mediated by shear gradient flows, from the macroscopic to the electronic transition level. Dislocations in the structure of the aggregate could justify the formation of chirality at the level of the electronic transitions once the mesophases can be sculptured by hydrodynamic gradient flows