RESUMEN

The bulk photovoltaic effect is an experimentally verified phenomenon by which a direct charge current is induced within a non-centrosymmetric material by light illumination. Calculations of its intrinsic contribution, the shift current, are nowadays amenable from first-principles employing plane-wave bases. In this work, we present a general method for evaluating the shift conductivity in the framework of localized Gaussian basis sets that can be employed in both the length and velocity gauges, carrying the idiosyncrasies of the quantum-chemistry approach. The (possibly magnetic) symmetry of the system is exploited in order to fold the reciprocal space summations to the representation domain, allowing us to reduce computation time and unveiling the complete symmetry properties of the conductivity tensor under general light polarization.

RESUMEN

It is generally accepted that spin-dependent electron transmission may appear in chiral systems, even without magnetic components, as long as significant spin-orbit coupling is present in some of its elements. However, how this chirality-induced spin selectivity (CISS) manifests in experiments, where the system is taken out of equilibrium, is still debated. Aided by group theoretical considerations and nonequilibrium DFT-based quantum transport calculations, here we show that when spatial symmetries that forbid a finite spin polarization in equilibrium are broken, a net spin accumulation appears at finite bias in an arbitrary two-terminal nanojunction. Furthermore, when a suitably magnetized detector is introduced into the system, the net spin accumulation, in turn, translates into a finite magneto-conductance. The symmetry prerequisites are mostly analogous to those for the spin polarization at any bias with the vectorial nature given by the direction of magnetization, hence establishing an interconnection between these quantities.

RESUMEN

Spin-orbit coupling gives rise to a range of spin-charge interconversion phenomena in nonmagnetic systems where certain spatial symmetries are reduced or absent. Chirality-induced spin-selectivity (CISS), a term that generically refers to a spin-dependent electron transfer in nonmagnetic chiral systems, is one such case, appearing in a variety of seemingly unrelated situations ranging from inorganic materials to molecular devices. In particular, the origin of CISS in molecular junctions is a matter of an intense current debate. Here, we derive a set of geometrical conditions for this effect to appear, hinting at the fundamental role of symmetries beyond otherwise relevant quantitative issues. Our approach, which draws on the use of point-group symmetries within the scattering formalism for transport, shows that electrode symmetries are as important as those of the molecule when it comes to the emergence of a spin-polarization and, by extension, to the possible appearance of CISS. It turns out that standalone metallic nanocontacts can exhibit spin-polarization when relative rotations which reduce the symmetry are introduced. As a corollary, molecular junctions with achiral molecules can also exhibit spin-polarization along the direction of transport, provided that the whole junction is chiral in a specific way. This formalism also allows the prediction of qualitative changes of the spin-polarization upon substitution of a chiral molecule in the junction with its enantiomeric partner. Quantum transport calculations based on density functional theory corroborate all of our predictions and provide further quantitative insight within the single-particle framework.

RESUMEN

Commercial thyme and lavender essential oils were analysed by GC/MS. Sixty-six compounds accounting for 98.6-99.6% of total essential oil were identified. Thymol (52.14 ± 0.21%), followed by p-cymene (32.24 ± 0.16%), carvacrol (3.71 ± 0.01%) and γ-terpinene (3.34 ± 0.02%), were the main compounds in thyme essential oil, while large amounts of oxygenated monoterpenes linalool acetate (37.07 ± 0.24%) and linalool (30.16 ± 0.06%) were found in lavender one. In vitro antifungal activity of the essential oils was evaluated at 200 and 300 µg/mL against 10 phytopathogenic and post-harvest fungi, which significantly affect agriculture. Micelial growth inhibition was calculated for each tested fungus and dose. Thyme essential oil showed satisfactory results with 90-100% growth inhibition in almost all the assayed fungi at 300 µg/mL, while lavender essential oil showed no noteworthy inhibition data at either dose, and its growth was even enhanced. Thyme essential oil represents a natural alternative to control harvest and post-harvest fungi, and to extend the shelf-life of agriculture products.

Asunto(s)

RESUMEN

INTRODUCTION: Anxiety has negative effects on the cognitive performance and psychosocial adjustment of elderly people. Given the high prevalence of anxiety symptoms in patients suffering from cognitive impairment, it has been suggested that these symptoms may be an early marker of dementia. The State-Trait Anxiety Inventory (STAI) is one of the most widely-used scales for evaluating anxiety in elderly people. However, inasmuch as the STAI may be difficult to apply to older people, having a short form of it would be desirable. METHODS: The participants comprised 489 community-dwelling individuals aged 68 years and over. All of them were volunteers in a longitudinal study for early detection of Alzheimer' Disease (Proyecto Vallecas). The full sample was divided in two homogeneous subgroups: Group A, used to reduce the number of items and response options, and Group B, the group used to determine the psychometric properties of the new short form (STAIr). RESULTS: A dichotomous Rasch model was used to obtain the STAIr. No statistically significant differences for STAIr scores were found with respect to sociodemographic variables. Psychometric properties and normative data were obtained for the new short version. CONCLUSIONS: The STAIr is composed of 13 items and data fits the model well. Since it is short and easy to apply to elderly people, STAIr will be very useful in clinical and research settings.

Asunto(s)

Asunto(s)

Asunto(s)

RESUMEN

No disponible

No disponible

Asunto(s)

RESUMEN

Objetivo: evaluar la utilidad práctica de una herramienta que cuantifica de forma objetiva, numérica, el potencial sociofamiliar de cuidados domiciliarios en pacientes paliativos. Ensayar las condiciones y requisitos para plantear un estudio de validación. Método: la escala se basa en el formulario expuesto, que valora 5 dimensiones: Cuidadores, características del domicilio, situación socioeconómica, asistencia médica y otros apoyos sociales. Cada una de ellas, se desglosa en ítems, que se cuantifican numéricamente pudiendo oscilar el resultado total entre 0 y 100. Para su valoración numérica hemos desarrollado una sencilla aplicación informática, que se puede conseguir libremente en nuestra página Web: http://www.infonegocio.com/inssocial. En este trabajo hemos evaluado 50 registros, correspondientes a 48 pacientes no seleccionados ingresados en nuestra Unidad. Resultados: se detallan el estudio estadístico descriptivo de las puntuaciones globales obtenidas, la distribución de los resultados por frecuencia y porcentaje, así como los valores obtenidos en cada una de las dimensiones, consideradas individualmente. Subjetivamente, las puntuaciones resultantes nos parecen proporcionadas y acordes a las circunstancias observadas en pacientes concretos. En nuestra opinión es un instrumento útil en la identificación de problemas y objetivos a trabajar por el equipo, y es un índice dinámico, sensible y susceptible de variar en base a actuaciones concretas. Conclusiones: la Escala de Capacidad de Cuidados en Domicilio (ECCD) puede ser una herramienta útil en la valoración integral de nuestros enfermos. Algunos aspectos metodológicos deben ser discutidos, corregidos y consensuados por expertos. Es necesario un estudio de validación amplio y riguroso, que determine su valor real (AU)

Objective: the objective was to evaluate the practical utility of a tool to objectively and numerically quantitate the socio-familial potential of home care for patients on palliative care, and also to rehearse conditions and requirements in order to outline a validation study. Method: the scale is based on the shown form, which assesses 5 dimensions: caregivers, home characteristics, socio-economic status, medical care, and other social support. Each one of them is made up by quantified items whose results may oscillate between 0 and 100. For their numeric valuation we developed a simple computer application that you can download free of charge from our Web page: http://www.infonegocio.com/inssocial. In this work we have evaluated 50 registrations, corresponding to 48 non-selected patients hospitalized in our Unit. Results: we detail the descriptive statistical study of the overall scores obtained, the distribution of results according to frequency and percentage, and the values obtained for each individual dimension. Subjectively, we find the resulting scores proportionate and in accordance with the circumstances seen in specific patients. In our opinion this is a useful tool for the identification of problems and objectives for the team to work upon, as well as a dynamic and sensitive index that may vary depending on specific procedures. Conclusions: Escala de Capacidad de Cuidados en Domicilio (ECCD)(Home Care Capacity Scale-HCCS) may be a useful tool for the integral assessment of patients. Some methodological aspects should be discussed, corrected, and agreed upon by experts. An extensive, rigorous validation study is needed to establish its real worth (AU)

Asunto(s)

RESUMEN

A functional genomics project has been initiated to approach the molecular characterization of the main biological and agronomical traits of citrus. As a key part of this project, a citrus EST collection has been generated from 25 cDNA libraries covering different tissues, developmental stages and stress conditions. The collection includes a total of 22,635 high-quality ESTs, grouped in 11,836 putative unigenes, which represent at least one third of the estimated number of genes in the citrus genome. Functional annotation of unigenes which have Arabidopsis orthologues (68% of all unigenes) revealed gene representation in every major functional category, suggesting that a genome-wide EST collection was obtained. A Citrus clementina Hort. ex Tan. cv. Clemenules genomic library, that will contribute to further characterization of relevant genes, has also been constructed. To initiate the analysis of citrus transcriptome, we have developed a cDNA microarray containing 12,672 probes corresponding to 6875 putative unigenes of the collection. Technical characterization of the microarray showed high intra- and inter-array reproducibility, as well as a good range of sensitivity. We have also validated gene expression data achieved with this microarray through an independent technique such as RNA gel blot analysis.

Asunto(s)

RESUMEN

Angiotensin (Ang-II) is a key molecule in the development of cardiac ischaemic disorders and displays proinflammatory activity in vivo. Since intracellular cyclic nucleotides elevating agents have proved to be effective modulators of leukocyte recruitment, we have evaluated their effect on Ang-II-induced leukocyte-endothelial cell interactions in vivo using intravital microscopy within the rat mesenteric microcirculation. Pretreatment with iloprost significantly inhibited (1 nM) Ang-II-induced increase in leukocyte rolling flux, adhesion and emigration at 60 min by 96, 92 and 90% respectively, and returned leukocyte rolling velocity to basal levels. Pretreatment with salbutamol or co-superfusion with forskolin exerted similar effects. When theophylline was administered, leukocyte rolling flux, adhesion and emigration elicited by Ang-II were significantly attenuated by 81, 89 and 71% respectively. Rolipram administration caused similar reduction of Ang-II-induced leukocyte responses. Co-superfusion of Ang-II with the NO-donor, spermine-NO, or 8-Br-cyclic GMP, or pretreatment with a transdermal nytroglycerin patch, resulted in a significant reduction of the leukocyte-endothelial cell interactions elicited by Ang-II. Salbutamol preadministration did not modify leukocyte-endothelial cell interactions elicited by either L-NAME or L-NAME+Ang-II, indicating that the inhibitory leukocyte effects caused by cyclic AMP-elevating agents are mediated through NO release. In conclusion, we have provided evidence that cyclic AMP elevating agents and NO donors, are potent inhibitors of Ang-II-induced leukocyte-endothelial cell interactions. Thus, they could constitute a powerful therapeutical tool in the control of the leukocyte recruitment characteristic of the vascular lesions that occur in cardiovascular disease states where Ang-II plays a critical role.

Asunto(s)

RESUMEN

Activation tagging using T-DNA vectors that contain multimerized transcriptional enhancers from the cauliflower mosaic virus (CaMV) 35S gene has been applied to Arabidopsis plants. New activation-tagging vectors that confer resistance to the antibiotic kanamycin or the herbicide glufosinate have been used to generate several tens of thousands of transformed plants. From these, over 30 dominant mutants with various phenotypes have been isolated. Analysis of a subset of mutants has shown that overexpressed genes are almost always found immediately adjacent to the inserted CaMV 35S enhancers, at distances ranging from 380 bp to 3.6 kb. In at least one case, the CaMV 35S enhancers led primarily to an enhancement of the endogenous expression pattern rather than to constitutive ectopic expression, suggesting that the CaMV 35S enhancers used here act differently than the complete CaMV 35S promoter. This has important implications for the spectrum of genes that will be discovered by this method.

Asunto(s)

RESUMEN

Flowering of Arabidopsis is regulated by a daylength-dependent pathway that accelerates flowering in long days and a daylength-independent pathway that ensures flowering in the absence of inductive conditions. These pathways are genetically separable, as there are mutations that delay flowering in long but not short days. Conversely, mutations that block synthesis of the hormone gibberellin abolish flowering in short days, but have on their own only a minor effect in long days. A third pathway, the autonomous pathway, probably acts by modulating the other two pathways. Understanding where and how these pathways are integrated is a prerequisite for understanding why similar environmental or endogenous cues can elicit opposite flowering responses in different plants. In Arabidopsis, floral induction leads ultimately to the upregulation of floral meristem-identity genes such as LEAFY, indicating that floral inductive signals are integrated upstream of LEAFY Here we show that gibberellins activate the LEAFY promoter through cis elements that are different from those that are sufficient for the daylength response, demonstrating that the LEAFY promoter integrates environmental and endogenous signals controlling flowering time.

Asunto(s)

RESUMEN

Volatile compounds from the aerial parts of Teucrium lepicephalum Pau and Teucrium carolipaui C. Vicioso ex Pau, both belonging to the Teucrium pumilum aggregate, were analysed by capillary GC and GC-MS. From the common and specific compounds (mono- and sesquiterpenes) of the two taxa, chemical characterization was carried out and taxonomic relationships were assessed. Application of the cluster and k-means discriminant analysis shows a differential chemical relationship between T. lepicephalum and Teucrium carolipaui.

Asunto(s)

RESUMEN

The essential oil composition from Sideritis tragoriganum has been investigated by capillary gas chromatography and gas chromatography-mass spectrometry. Among the 47 identified mono- and sesquiterpenes, alpha-bisabolol is the most prominent component. Correlation analysis of essential oil components from this population of S. tragoriganum with two other geographically distinct populations revealed the existence of unrelated chemical types.

Asunto(s)

RESUMEN

OBJECTIVES: To determine the prevalence of urine incontinence (UI) among the over-60 population treated in primary care, identifying the types and associated epidemiological factors. DESIGN: Descriptive and crossover. SETTING: Primary care. PATIENTS: Sample of 400 people aged 60 or over, stratified by sex and chosen from those who attended their health centre spontaneously for a consultation. MEASUREMENTS AND RESULTS: Age, sex, chronic illnesses, treatments, previous childbirths, grade of immobility and presence or absence of involuntary discharge of urine. If the reply was positive: frequency, characteristics and evolution of UI, and prior consultations on the problem were also measured. 400 people (254 women and 146 men). Mean age: 71 (SD = 7.3 years). 145 people (36.2%) recognised they had UI. 43.3% of women and 23.9% of men (p < 0.001) were incontinent. UI prevalence increased with age: 31.7% among the 60-69 year old group; 35% among the 70-79 group; and 53.3% in those over 80. Among women the most common types are stress and urge incontinence, whereas among men the most common are urge and overflow UI. UI prevalence is greater among women with previous childbirths and among immobile patients. Of the 145 people who recognised their UI, only 31 (21.3%) had previously consulted the doctor on this problem, although men had consulted significantly more than women (40% vs. 15.4%; p < 0.01). CONCLUSIONS: Over a third of the people over 60 in our clinics suffer from UI. Prevalence increases with age and is greater among women, especially if there is a history of childbirth. Urge UI predominates among men and stress UI among women. Most people with UI do not consult concerning their problem, for which reason, so as to identify it and adopt corrective measures, women especially must be systematically asked about the symptom.

Asunto(s)

RESUMEN

The use of four cyclodextrins (three native and one beta-CD derivative) as NMR chiral solvating agents to resolve the enantiomers of (+/-)-cizolirtine, 1, and its chemical precursor (the carbinol, (+/-)-2), was investigated. The best enantiodiscrimination occurred when beta-cyclodextrin was used. ROESY experiments were performed to qualitatively ascertain the most probable host-guest structures in D(2)O solution, and the binding features found were explained in terms of spatial fitting of the guest molecules into the macrocyclic cavities. No geometrical differences were noted between the two diastereomeric complexes formed by a cyclodextrin and a racemic substrate, so the magnetic nonequivalence induced on guest protons by the enantioselective binding had to be explained as a result of subtle disparities in the orientation and/or the conformational state of the complexed enantiomers.

Asunto(s)

RESUMEN

Phytochromes and gibberellins (GAs) coordinately regulate multiple aspects of Arabidopsis development. Phytochrome B (PHYB) promotes seed germination by increasing GA biosynthesis, but inhibits hypocotyl elongation by decreasing the responsiveness to GAs. Later in the life cycle of the plant, PHYB and GAs have opposite effects on flowering. PHYB delays flowering, while GAs promote flowering, particularly under noninductive photoperiods. To learn how PHYB and GAs interact in the control of flowering, we have analyzed the effect of a phyB mutation on flowering time and on the expression of the floral meristem-identity gene LFY (LEAFY). We show that the early flowering caused by phyB correlated with an increase in LFY expression, which complements our previous finding that GAs are required for activation of LFY under noninductive photoperiods (M.A. Blázquez, R. Green, O. Nilsson, M.R. Sussman, D. Weigel [1998] Plant Cell 10: 791-800). Since phyB did not change the GA responsiveness of the LFY promoter and suppressed the lack of flowering of severe GA-deficient mutants under short days, we propose that PHYB modulates flowering time at least partially through a GA-independent pathway. Interestingly, the effects of PHYB on flowering do not seem to be mediated by transcriptional up-regulation of genes such as CO (CONSTANS) and FT (Flowering locus T), which are known to mediate the effects of the photoperiod-dependent floral-induction pathway.

Asunto(s)

RESUMEN

Among the genes that control the transition to flowering in Arabidopsis is a large group whose inactivation causes a delay in flowering. It has been difficult to establish different pathways in which the flowering-time genes might act, because mutants with lesions in these genes have very similar phenotypes. Among the putative targets of the flowering-time genes is another group of genes, which control the identity of individual meristems. Overexpression of one of the meristem-identity genes, LEAFY, can cause the precocious generation of flowers and thus early flowering. We have exploited the opposite phenotypes seen in late-flowering mutants and LEAFY overexpressers to clarify the genetic interactions between flowering-time genes and LEAFY. According to epistatic relationships, we can define one class of flowering-time genes that affects primarily the response to LEAFY activity, and another class of genes that affects primarily the transcriptional induction of LEAFY. These observations allow us to expand previously proposed models for the genetic control of flowering time.

Asunto(s)