Imaging dielectric relaxation in nanostructured polymers by frequency modulation electrostatic force microscopy

We have developed a method for imaging the temperature-frequency dependence of the dynamics of nanostructured polymer films with spatial resolution. This method provides images with dielectric compositional contrast well decoupled from topography. Using frequency-modulation electrostatic-force-microscopy, we probe the local frequency-dependent (0.1–100 Hz) dielectric response through measurement of the amplitude and phase of the force gradient in response to an oscillating applied electric field. When the phase is imaged at fixed frequency, it reveals the spatial variation in dielectric losses, i.e., the spatial variation in molecular/dipolar dynamics, with 40 nm lateral resolution. This is demonstrated by using as a model system; a phase separated polystyrene/polyvinyl-acetate (PVAc) blend. We show that nanoscale dynamic domains of PVAc are clearly identifiable in phase images as those which light-up in a band of temperature, reflecting the variations in the molecular/dipolar dynamics approaching the glass transition temperature of PVAc

Measuring dielectric properties at the nanoscale using Electrostatic Force Microscopy

Several electrostatic force microscopy (EFM) - based methods have been recently developed to study the nanoscale dielectric properties of thin insulating layers. Some methods allow measuring quantitatively the static dielectric permittivity whereas some others provide qualitative information about the temperature-frequency dependence of dielectric properties. In this chapter, all these methods are described and illustrated by experiments on pure and nanostructured polymer films. A section is dedicated to EFM probe - sample models and especially to the Equivalent Charge Method (ECM)

neuroanatomical basis of behavioral disturbances in patients with prefrontal lesions

The role of the frontal lobe in control of behavioral and cognitive abilities is explored in a group of 34 patients with brain lesions restricted to the prefrontal cortex. The scores in both structured behavioral questionnaires and standard neuropsychological tests were analyzed using the injured area of the frontal lobe as the independent variable. Our results show that patients with simultaneous lesions in supero– and inferomedial areas of the prefrontal cortex exhibit higher behavioral disturbances. Bilateral lesions also are associated with greater behavioral troubles. On the contrary, cognitive abilities are globally impaired in prefrontal patients. Results are discussed in relation to current models of the organization of the prefrontal cortex and its role on behavior control

Ejes temáticos del pensamiento racial en Puerto Rico: una aproximación.

The article considers various books and articles on race and racism in Puerto Rico. It is organized around two sections: the first focuses on theoretical frameworks over race in the social sciences. The second section presents the main ideological and structural axes for the social construction of race, racism and racialization in Puerto Rico. Finally the author proposes a research agenda on race in Puerto Rico.Esta reflexión tiene como base una selección de artículos y libros relacionados con el tema racial en Puerto Rico. En la primera parte se examina una selección de escritos teóricos sobre el tema de la raza. En la segunda parte se abordan los ejes temáticos que han guiado dicha investigación de acuerdo a factores ideológicos y estructurales para la construcción de la raza y el tema racial en Puerto Rico. Finalmente, la autora propone una agenda de investigación sobre el tema de la raza en Puerto Rico

Algoritmos de derivación y confirmación diagnóstica de citología cervical atípica: desafíos para la actualización

Indexación: ScieloEl Programa Nacional de Pesquisa y Control del Cáncer Cervicouterino de Chile ha contribuido al descenso sostenido de la mortalidad por cáncer de cuello uterino. Para la reducción de esta mortalidad ha sido fundamental la citología exfoliativa del cérvix, la que no está exenta de resultados inciertos. En este sentido, los frotis clasificados como atípicos se consideran ambiguos por la presencia de anomalías celulares de difícil determinación, lo que se traduce en un diagnóstico de probabilidad incierta. En la literatura nacional como internacional, se manifiesta un notorio interés por unificar la nomenclatura citológica cervical y los algoritmos de derivación y confirmación diagnóstica, para el manejo clínico de las mujeres con anomalías citológicas cervicales y lesiones precursoras de cáncer cervicouterino. Por lo anterior, se considera relevante los estudios que proporcionen evidencia clínica epidemiológica actualizada, que permitan optimizar el cumplimiento del Programa Nacional de Cáncer Cervicouterino, conducentes al logro de los Objetivos Sanitarios del período 2011-2020.The National Research and Control of Cervical Cancer in Chile had contributed to the sustained decline in mortality from cervical cancer. The exfoliative cytology of the cervix has been to reduce this mortality, which is not without uncertain results. The smears classified as atypical are considered ambiguous by the presence of cellular abnormalities difficult to determine, resulting in a diagnosis of uncertain probability. The literature, both nationally and internationally, is widespread interest to unify the nomenclature cervical cytology and the support of the derivation algorithms for the clinical management of women with cytologic abnormalities cervical and cervical cancer precursor lesions. Therefore, it is relevant to perform studies the provide updated epidemiological clinical evidence, to optimize the performance of the National Program for the achievement of health objectives for the period 2011-2020.http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-75262012000400015&nrm=is

Mexican-origin parent and child reported neighborhood factors and youth substance use

BackgroundStructural oppression affects health behaviors through residence in suboptimal neighborhoods and exposure to community violence. Youth and parents report perceptions of neighborhood factors that can affect youth substance use behaviors. Given that Latinx youth report higher levels of perceived community violence than other racial and ethnic groups, it is imperative to examine how youth- and parent-perceived neighborhood-level factors may relate to youth substance use.MethodsData were collected using clinical interviews with family triads (fathers, mothers, and youth) and parent–child dyads (father or mother and youth) enrolled in the Seguimos Avanzando study of 344 Mexican-origin families in Indiana. Neighborhood measures, including perceptions of exposure to violence, neighborhood characteristics, and neighborhood collective efficacy, were included in parent and youth surveys. Self-report measures for past year alcohol and drug use were included in the youth survey only. T-tests were conducted to estimate differences in neighborhood reports among the sample triads. A series of linear regression models were used to estimate the associations between youth-, mother-, and father-reported perceptions of neighborhood factors and youth substance use.ResultsPreliminary results indicate that fathers reported higher levels of exposure to violence than mothers [t(163) = 2.33, p = 0.02] and youth [t(173) = 3.61, p < 0.001]. Youth reported lower negative neighborhood characteristics than mothers [t(329) = 6.43, p < 0.001] and fathers [t(169) = 3.73, p < 0.001]. Youth reported significantly better neighborhood collective efficacy than mothers [t(296) = 3.14, p = 0.002], but not statistically different from fathers. Results from the primary analysis showed that youth exposure to violence was positively associated with youth substance use (b = 0.24, SE = 0.06, p < 0.0001), but the youth’s neighborhood characteristics and collective efficacy were not significantly associated with youth substance use. None of the parent-reported neighborhood variables were associated with youth substance use.ConclusionThe discrepant findings between parent and youth reports of perceived neighborhood characteristics and substance use have important implications for researchers and community stakeholders, and for developing targeted interventions and prevention strategies. Our study highlights the need to address youth experience of community violence and to prioritize creating safe and inclusive neighborhood environments. Potential strategies include improving community resources, strengthening social support networks, promoting open communication about neighborhood risks, and fostering collaborative efforts to address substance use behaviors

Molecular Identification and Quantification of Tetracycline and Erythromycin Resistance Genes in Spanish and Italian Retail Cheeses

Large antibiotic resistance gene pools in the microbiota of foods may ultimately pose a risk for human health. This study reports the identification and quantification of tetracycline- and erythromycin-resistant populations, resistance genes, and gene diversity in traditional Spanish and Italian cheeses, via culturing, conventional PCR, real-time quantitative PCR (qPCR), and denaturing gradient gel electrophoresis (DGGE). The numbers of resistant bacteria varied widely among the antibiotics and the different cheese varieties; in some cheeses, all the bacterial populations seemed to be resistant. Up to eight antibiotic resistance genes were sought by gene-specific PCR, six with respect to tetracycline, that is, tet(K), tet(L), tet(M), tet(O), tet(S), and tet(W), and two with respect to erythromycin, that is, erm(B) and erm(F). The most common resistance genes in the analysed cheeses were tet(S), tet(W), tet(M), and erm(B). The copy numbers of these genes, as quantified by qPCR, ranged widely between cheeses (from 4.94 to 10.18 log10/g). DGGE analysis revealed distinct banding profiles and two polymorphic nucleotide positions for tet(W)-carrying cheeses, though the similarity of the sequences suggests this tet(W) to have a monophyletic origin. Traditional cheeses would therefore appear to act as reservoirs for large numbers of many types of antibiotic resistance determinants.The study was partially supported by a Spain-Italy bilateral collaboration program (Ref. IT2009-0080 and IT105MD12L). Financial support was further provided by projects from CICYT (Ref. AGL2011-24300-ALI) and INIA (Ref. RM2011-00005-00-00). A. B. Flórez and S. Delgado were supported by research contracts under Juan de la Cierva Program (Ref. JCI-2010-07457 and JCI-2008-02391, resp.). A. Alegría was awarded a scholarship of the Severo Ochoa program from FICYT (Ref. BP08-053).Peer Reviewe

Garvicins AG1 and AG2 : two novel class IId bacteriocins of lactococcus garvieae Lg-Granada

Funding: This research was funded by the Spanish Ministry of Science, Innovation, and Universities, grant number RTI2018-098530-B-I00. The APC was funded by the Spanish Ministry of Science, Innovation, and Universities, grant number RTI2018-098530-B-I00.Lactococcus garvieae causes infectious diseases in animals and is considered an emerging zoonotic pathogen involved in human clinical conditions. In silico analysis of plasmid pLG50 of L. garvieae Lg-Granada, an isolate from a patient with endocarditis, revealed the presence of two gene clusters (orf 46–47 and orf 48–49), each one encoding a novel putative bacteriocin, i.e., garvicin AG1 (GarAG1; orf 46) and garvicin AG2 (GarAG2; orf 48), and their corresponding immunity proteins (orf 47 and orf 49). The chemically synthesised bacteriocins GarAG1 and GarAG2 presented inhibitory activity against pathogenic L. garvieae strains, with AG2 also being active against Listeria monocytogenes, Listeria ivanovii and Enterococcus faecalis. Genetic organisation, amino acid sequences and antimicrobial activities of GarAG1 and GarAG2 indicate that they belong to linear non-pediocin-like one-peptide class IId bacteriocins. Gram-positive bacteria that were sensitive to GarAG2 were also able to ferment mannose, suggesting that this bacteriocin could use the mannose phosphotransferase transport system (Man-PTS) involved in mannose uptake as a receptor in sensitive strains. Intriguingly, GarAG1 and GarAG2 were highly active against their own host, L. garvieae Lg-Granada, which could be envisaged as a new strategy to combat pathogens via their own weapons.Publisher PDFPeer reviewe

Massive open star clusters using the VVV survey III: A young massive cluster at the far edge of the Galactic bar

Context: Young massive clusters are key to map the Milky Way's structure, and near-IR large area sky surveys have contributed strongly to the discovery of new obscured massive stellar clusters. Aims: We present the third article in a series of papers focused on young and massive clusters discovered in the VVV survey. This article is dedicated to the physical characterization of VVV CL086, using part of its OB-stellar population. Methods: We physically characterized the cluster using $JHK_S$ near-infrared photometry from ESO public survey VVV images, using the VVV-SkZ pipeline, and near-infrared $K$-band spectroscopy, following the methodology presented in the first article of the series. Results: Individual distances for two observed stars indicate that the cluster is located at the far edge of the Galactic bar. These stars, which are probable cluster members from the statistically field-star decontaminated CMD, have spectral types between O9 and B0V. According to our analysis, this young cluster ($1.0$ Myr $<$ age $< 5.0$ Myr) is located at a distance of $11^{+5}_{-6}$ kpc, and we estimate a lower limit for the cluster total mass of $(2.8^{+1.6}_{-1.4})\cdot10^3 {M}_{\odot}$. It is likely that the cluster contains even earlier and more massive stars.Comment: Accepted for publication as a Letter in A&

Whole genome analysis as a tool for the safety assessment of antibiotic resistance in food-processing bacteria

Trabajo presentado en la 2nd EFSA Scientific Conference, celebrado en Milán, Italia, del 14 al 16 de octubre de 2015Acquisition of antibiotic resistances (AR) by pathogens leads ultimately to a failure of antibiotic therapy. The food chain is considered a key player in the transmission of AR determinants to pathogens from reservoirs in commensal and beneficial bacteria. Therefore, the absence of transmissible AR genes in bacteria used as starter and adjunct cultures for food and feed processing is considered to be critical (EFSA, 2012; EFSA Journal, 10:2740). Genome sequencing allows the inspection of the whole genetic makeup of bacteria in the search for the basis of desirable and undesirable traits, including that of AR. Thus, in silico sequence analysis and comparison against databases can be used as a tool for the safety assessment of microorganisms intended to be used in food systems. This communication reports on the genome analysis of three Leuconostoc mesenteroides strains of dairy origin showing atypical resistances to tetracycline (LbT16), erythromycin and clindamycin (LbE15), and kanamycin, streptomycin, tetracycline and virginiamycin (LbE16). Genes encoding for erythromycin [erm(B)] and tetracycline [tet(S)] resistance had already been detected by PCR. Genome analysis confirmed the presence of these genes and identified others which encode uncommon AR in lactic acid bacteria. Analysis of the genes and their flanking regions revealed a potential of some to be horizontally transferred to other bacteria. This study demonstrates the effectiveness of combining genome sequencing and bioinformatics analysis as an affordable tool for the safety assessment of food bacteria. This innovative approach could become a novel paradigm in the selection programs of starters for the food industry.Peer Reviewe