Dielectric response of modified Hubbard models with neutral-ionic and Peierls transitions

The dipole P(F) of systems with periodic boundary conditions (PBC) in a static electric field F is applied to one-dimensional Peierls-Hubbard models for organic charge-transfer (CT) salts. Exact results for P(F) are obtained for finite systems of N = 14 and 16 sites that are almost converged to infinite chains in deformable lattices subject to a Peierls transition. The electronic polarizability per site, \alpha_{el} = (\partial P/\partial F)_0, of rigid stacks with alternating transfer integrals t(1 +/- \delta) diverges at the neutral-ionic transition for \delta = 0 but remains finite for \delta > 0 in dimerized chains. The Peierls or dimerization mode couples to charge fluctuations along the stack and results in large vibrational contributions, \alpha_{vib}, that are related to \partial P/\partial \delta and that peak sharply at the Peierls transition. The extension of P(F) to correlated electronic states yields the dielectric response \kappa of models with neutral-ionic or Peierls transitions, where \kappa peaks >100 are found with parameters used previously for variable ionicity \rho and vibrational spectra of CT salts. The calculated \kappa accounts for the dielectric response of CT salts based on substituted TTFs (tetrathiafulvalene) and substituted CAs (chloranil). The role of lattice stiffness appears clearly in models: soft systems have a Peierls instability at small \rho and continuous crossover to large \rho, while stiff stacks such as TTF-CA have a first-order transition with discontinuous \rho that is both a neutral-ionic and Peierls transition. The transitions are associated with tuning the electronic ground state of insulators via temperature or pressure in experiments, or via model parameters in calculations.Comment: 10 pages, 9 figures; J.Chem.Phys., in pres

Coworkers, Networks, and Job Search Outcomes

Social networks are an important channel of information transmission in the labor market. In this paper investigate how displaced workers searching for new jobs benefit from information provided by their former coworkers. In line with the theoretical and empirical literature we find that the employment status networks members matters for the job finding rate. We further analyze the mechanisms through which employed contacts affect job search outcomes and find that (i) the types of firms at which the contacts work are important and (ii) contacts with similar characteristics as the displaced worker lead to better outcomes. Our findings strongly indicate that job referrals from network members are the main mechanism by which social contacts influence job search outcomes

Sistematización de resultados. Encuesta sobre Situaciones Familiares y Desempeños Sociales de las mujeres en Montevideo y el Área Metropolitana, 2001.

This document presents a preliminar overview of the results of a survey about family structures and social outcomes. The information was collected between March and October of 2001. The sample included 1806 women aged 25 to 54 years old, living in Montevideo and its suburban areas in Canelones and San José (Uruguay).

Neoformation of soil aggregates after a volcano eruption in meadows of Northern Patagonia, Argentina

In June 2011, a natural event occurred in Patagonia, Argentina: The “Puyehue-Cordón Caulle” volcanic complex erupted, and particles from tephras (1-5cm) to very fine volcanic ash (44-500?m) where deposited in the direction of prevailing winds (West to East). The ash was biologically inert, with no organic compounds, neutral pH and low electrical conductivity. The objective was to study neoformation processes of soil aggregates in wet meadows after volcano eruptionEstación Experimental Agropecuaria BarilocheFil: Enriquez, Andrea Soledad. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche; ArgentinaFil: Cremona, María Victoria. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche; ArgentinaFil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; ArgentinaFil: Six, Johan. Escuela Politécnica Federal de Zurich; Suiz

First record of the invasive powderpost beetle Lyctus africanus Lesne (Coleoptera: Bostrichidae) infesting wooden furniture in Italy

Wood-boring beetles are significant pests that can rapidly spread through wooden materials, leading to substantial global economic losses. Invasive species targeting wood are frequently detected in Europe and North America, with the recent climatic conditions in the Mediterranean where climatic conditions have facilitated their establishment. Among these, species from the Bostrichidae family are particularly noteworthy due to their impact. In this study, we report the first record of the non-native powder post beetle Lyctus africanus, in timber used for art crafts in Italy, indicating its spread. An early detection and rapid reporting are the most important actions in the successful management of such non-indigenous species. Additionally, we provide illustrations and diagnosis for pest identification. We then highlight the list of possible wood species hosts, provide a general overview of infestations and review the control options for this destructive pest including chemical treatments, use of pheromone traps and the search for biological agents

Retrospective analysis of bacteraemia due to extended-spectrum beta-lactamase-producing Enterobacterales: the challenge of healthcare-associated infections

Objectives: Healthcare-associated bacteraemia is defined as bacteraemia diagnosed ≤48 h after hospital admission in patients recently exposed to healthcare procedures or settings. It differs from hospital-acquired bacteraemia, which is diagnosed >48 h after hospital admission. Healthcare-associated bacteraemia is reported increasingly, often due to resistant pathogens including extended-spectrum beta-lactamase (ESBL) producers, representing a challenge to empirical treatment. This study aimed to assess the appropriateness of empirical treatment for ESBL bacteraemia at the authors' centre, to perform a descriptive analysis according to the mode of infection acquisition (community-acquired, healthcare-associated, hospital-acquired), and to assess the risk factors for mortality. Methods: A retrospective study on patients with ESBL bacteraemia was undertaken. Results: In total, 129 consecutive cases of bacteraemia due to ESBL producers were included in this study. Compared with community- and hospital-acquired bacteraemia, healthcare-associated bacteraemia affected older patients (P=0.001) and patients with higher Charlson Comorbidity Index scores (P=0.007), and was more frequently associated with piperacillin-tazobactam resistance (P=0.025) and multi-drug resistance (P=0.026). Overall, ineffective empirical treatment was common (42%). Factors associated with 30-day mortality were septic shock [odds ratio (OR) 7.096, 95% confidence interval (CI) 2.58-24.58], high Pitt score (OR 6.636, 95% CI 1.71-23.62) and unknown source of bacteraemia (OR 19.28, 95% CI 2.80-30.70). Conclusions: Antimicrobial stewardship interventions focusing on both in-hospital and community settings are advocated to better manage healthcare-associated infections due to ESBL producers

Migration Costs and Networks: household optimal investment in migration

International migration is an expensive form of investment, that only households relatively better off can afford. However poorer households have the higher incentive to migrate. Migration decision is conditional on the entry cost, expected returns and risks of migration. This paper, using data from Mexican rural and urban areas, examines the relation between household and community networks and costs and risks of migration focusing on the optimal investment in migration. To investigate an household optimal number of migrants this paper introduces a Three Step procedure to solve simultaneously for the endogeneity of network size and possible selection of migrants. The analysis confirms the inverted U-shaped relation between wealth and migration, stressing the importance of networks particularly in facilitating the migration of social strata belonging to the left tail of the income distribution. Moreover, in presence of sunk costs and/or high initial investment, household and community networks accomplish different functions

La ausencia de concordancia entre el clítico dativo y su referente nominal

El presente trabajo propone como tema de estudio la descripción de la relación de concordancia en número entre el objeto indirecto presente en la estructura oracional y el pronombre dativo para estudiar la duplicación de una forma plural con el pronombre átono singular le. En particular, nos ocupamos de la comparación de casos como (1) Les voy a hacer juicio a Twitter e Instagram, en los que se manifiesta concordancia en número entre el objeto y el pronombre, y (2) No levamos a crear problemas a los diplomáticos, en los que se evidencia ausencia de concordancia. El objetivo principal es aportar evidencia que permita indagar en un posible desgaste semántico del pronombre dativo, dado que el proceso de duplicación generalizada del objeto indirecto podría provocar que el clítico de dativo se vaya convirtiendo en una especie de morfema objetivo del verbo (Company, 2006) o de legitimador de un objeto oblicuo (Navarro, 2005), y le restaría valor como participante argumental (Torres Cacoullos, 2005). Esto provocaría la ausencia de concordancia de número entre el pronombre dativo singular y su referente nominal plural. En virtud de los principios del Enfoque, la descripción de las formas se realiza con atención a los contextos reales de aparición, y el análisis implica la medición de la significación estadística y representatividad de los datos a partir de pruebas objetivas. Por lo tanto, la metodología de este trabajo instrumenta un abordaje cualitativo y cuantitativo, a partir de la recolección de corpus de textos auténticos de la prensa escrita argentina de la actualidad. Se propone analizar el problema de la falta de concordancia con atención a aquellos factores lingüísticos que puedan condicionar la aparición de dicha estrategia, tales como la inanimación y posposición del objeto indirecto con respecto del verbo, y el número gramatical del objeto directo

Robotic Heller-Dor myotomy: 10-year monocentric experience compared with POEM

Achalasia is a rare motility disorder caused by an incomplete relaxation of the lower esophageal sphincter and loss of esophageal peristalsis. As a consequence, the bolus swallowing is hindered and the patients complain dysphagia, regurgitation, chest pain, respiratory symptoms and weight loss. Achalasia’s treatment has been varied over time, from therapies aiming to relax the lower sphincter of the esophagus, including drugs andBotox injection or mechanical dilatations, to surgical myotomy. Robotic or laparoscopic Heller-Dor procedure is considered the gold standard surgical treatment for symptomatic achalasia as it is proved to be effective and safe. As an alternative, Per-Oral Endoscopic Myotomy (POEM) was applied over the past decade, aiming to combine the same results of mini-invasive procedure to the advantages of endoscopic approach. In this study, we are going to compare the medium-long term results of mini-invasive Heller-Dor procedure, routinely performed in our Department, with those of POEM reported in literature

Hemodynamic findings in normotensive women with small for gestational age and growth restricted fetuses

INTRODUCTION: Fetal growth restriction (FGR) in most instances results as a consequence of primary placental dysfunction due to inadequate trophoblastic invasion. Maternal cardiac maladaptation to pregnancy has been proposed as a possible determinant of placental insufficiency and impaired fetal growth. This study aimed to compare the maternal hemodynamic parameters between normotensive women with small-for-gestational age (SGA) and FGR fetuses and to evaluate their correlation with neonatal outcome.MATERIAL AND METHODS: observational cohort study including singleton pregnancies referred to our tertiary care center due to fetal smallness. At the time of diagnosis, fetuses were classified as SGA or FGR according to the Delphi consensus criteria and pregnant women underwent hemodynamic assessment by using cardiac output monitor (USCOM 1A Ltd). A group of women with singleton uncomplicated pregnancies ≥35 weeks of gestation were recruited as controls. Cardiac output, systemic vascular resistance, stroke volume and heart rate were measured and compared among the three groups (controls vs. FGR vs. SGA). The correlation between antenatal findings and neonatal outcome was also evaluated by multivariate logistic regression analysis.RESULTS: 51 women with fetal smallness were assessed at 34.8±2.6 weeks. SGA and FGR were diagnosed in 22 and 29 cases, respectively. The control group included 61 women assessed at 36.5±0.8 weeks of gestation. Women with FGR had a lower cardiac output -Z score (respectively, -1.3±1.2 vs. -0.4±0.8 vs. -0.2±1.0; p<.001) and a higher systemic vascular resistance Z-score compared with both SGA and controls (respectively, 1.2±1.2 vs. 0.2±1.1 vs. -0.02±1.2; p<.001), while no difference in the hemodynamic parameters was found between women with SGA and controls. The incidence of NICU admission did not differ between SGA and FGR fetuses (18.2% vs 41.4%; p=0.13), however FGR had a longer hospitalization compared to SGA fetuses (14.2±17.7 vs. 4.5±1.6 days; p=0.02). Multivariate analysis showed that the cardiac output Z-score at diagnosis (p=0.012) and the birthweight Z-Score (p= 0.007) were independent predictors of the length of neonatal hospitalization.CONCLUSIONS: Different maternal hemodynamic profiles characterize women with SGA or FGR fetuses. Furthermore, a negative correlation was found between the maternal cardiac output and the length of neonatal hospitalization