185 research outputs found

    Model Compounds of Ruthenium−Alkene Intermediates in Olefin Metathesis Reactions

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    The development of a model system to study ruthenium−olefin complexes relevant to the mechanism of olefin metathesis is reported. Upon addition of 1,2-divinylbenzene to (H_2IMes)(py_2)(Cl)_2Ru CHPh (H_2IMes = 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene), two ruthenium−olefin adducts are formed. On the basis of ^1H NMR spectroscopy experiments and X-ray crystallographic analysis, these complexes are assigned as side-bound isomers in which the olefin and H_2IMes ligands are coordinated cis to each other. The dynamic interconversion of these two ruthenium complexes was determined to have a barrier of 19.1 ± 0.1 kcal/mol

    Physical and psychological aggression in dating relationships in Spanish university students

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    The presence of violent behaviors of a psychological and physical nature in dating relations was analyzed in a sample of Spanish university students between 18 and 27 years of age. The results indicate a high prevalence of both kinds of aggression in interpersonal relationships, revealing important typology differences between the sexes. Violent psychological behaviors (characterized by the presence of verbal aggression and coercive and jealous behaviors) and physical aggression were significantly higher in women, though the consequences of physical aggression were worse for the women’s health. The implications of the results and their possible relation with more severe violent acts in more stable, emotional relationships are discussed. Agresión física y psicológica en las relaciones de noviazgo en universitarios españoles. En el presente trabajo se analiza la presencia de comportamientos violentos de carácter psicológico y físico en las relaciones de noviazgo en una muestra de jóvenes universitarios españoles con edades comprendidas entre los 18 y los 27 años. Los resultados indican la alta prevalencia de ambos tipos de agresión en las relaciones interpersonales, encontrando diferencias importantes en cuanto a su tipología entre sexos. Así, la violencia de carácter psicológico (analizadas por la presencia de agresiones verbales y comportamientos coercitivos y celosos) y la agresión física resultaron ser significativamente superiores en el caso de las mujeres, aunque las consecuencias para la salud derivadas de la misma son más negativas para ellas. Se comentan, asimismo, las implicaciones de los resultados obtenidos y su posible relación con actos de violencia más graves en posteriores relaciones emocionales más estables

    Seawater softening of suture zones inhibits fracture propagation in Antarctic ice shelves

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    Suture zones are abundant on Antarctic ice shelves and widely observed to impede fracture propagation, greatly enhancing ice-shelf stability. Using seismic and radar observations on the Larsen C Ice Shelf of the Antarctic Peninsula, we confirm that such zones are highly heterogeneous, consisting of multiple meteoric and marine ice bodies of diverse provenance fused together. Here we demonstrate that fracture detainment is predominantly controlled by enhanced seawater content in suture zones, rather than by enhanced temperature as previously thought. We show that interstitial seawater can reduce fracture-driving stress by orders of magnitude, promoting both viscous relaxation and the development of micro cracks, the incidence of which scales inversely with stress intensity. We show how simple analysis of viscous buckles in ice-penetrating radar data can quantify the seawater content of suture zones and their modification of the ice-shelf’s stress regime. By limiting fracture, enhancing stability and restraining continental ice discharge into the ocean, suture zones act as vital regulators of Antarctic mass balance

    Validación de la versión modificada de la Conflicts Tactics Scale (M-CTS) en población juvenil española

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    La version modificada de la Conflicts Tactics Scale (M-CTS), realizada originalmente por Straus en 1979, es uno de los instrumentos más ampliamente utilizados para la detección de comportamientos violentos de carácter verbal y físico en las relaciones de noviazgo en jóvenes y adolescentes. El objetivo del presente trabajo fue analizar las propiedades psicométricas del instrumento y validar su adecuación en población española. La muestra estuvo compuesta por 5.355 jóvenes españoles pertenecientes a la Comunidad de Madrid, con edades comprendidas entre los 16 y los 26 años. A través de un Analisis Factorial Confirmatorio se identificaron cuatro factores consistentes con la teoría y las investigaciones previas: argumentación, agresión psicológica/verbal, agresión física leve y agresión física grave. Se concluye que la escala permite evaluar, con suficientes garantías psicométricas, la presencia de diferentes tipos de agresión en las relaciones de pareja en jóvenes y adolescentes

    Accommodation functions: co-dependency and relationship to refractive error

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    We assessed the extent to which different accommodative functions are correlated and whether accommodative functions predict the refractive error or the progression of myopia over a 12 month period in 64 young adults (30 myopes and 34 non-myopes). The functions were: amplitude of accommodation; monocular and binocular accommodative facility (6 m and 40 cm); monocular and binocular accommodative response to target distance; AC/A and CA/C ratios, tonic accommodation (dark focus and pinhole), accommodative hysteresis, and nearwork-induced transient myopia. Within groups of related accommodative functions (such as facility measures or open-loop measures) measurements on individuals were generally significantly correlated, however correlations between functions from different groups were generally not significant. Although accommodative amplitude and pinhole (open loop) accommodation were significantly different in myopes than in non-myopes, these functions were unrelated to myopia progression. Facility of accommodation and accommodative lag was independent predictors of myopia progression

    Marine reserves can mitigate and promote adaptation to climate change

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    Strong decreases in greenhouse gas emissions are required to meet the reduction trajectory resolved within the 2015 Paris Agreement. However, even these decreases will not avert serious stress and damage to life on Earth, and additional steps are needed to boost the resilience of ecosystems, safeguard their wildlife, and protect their capacity to supply vital goods and services. We discuss how well-managed marine reserves may help marine ecosystems and people adapt to five prominent impacts of climate change: acidification, sea-level rise, intensification of storms, shifts in species distribution, and decreased productivity and oxygen availability, as well as their cumulative effects. We explore the role of managed ecosystems in mitigating climate change by promoting carbon sequestration and storage and by buffering against uncertainty in management, environmental fluctuations, directional change, and extreme events. We highlight both strengths and limitations and conclude that marine reserves are a viable low-tech, cost-effective adaptation strategy that would yield multiple cobenefits from local to global scales, improving the outlook for the environment and people into the future

    How integrated are neurology and palliative care services? Results of a multicentre mapping exercise

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    Background: Patients affected by progressive long-term neurological conditions might benefit from specialist palliative care involvement. However, little is known on how neurology and specialist palliative care services interact. This study aimed to map the current level of connections and integration between these services. Methods: The mapping exercise was conducted in eight centres with neurology and palliative care services in the United Kingdom. The data were provided by the respective neurology and specialist palliative care teams. Questions focused on: i) catchment and population served; ii) service provision and staffing; iii) integration and relationships. Results: Centres varied in size of catchment areas (39-5,840 square miles) and population served (142,000-3,500,000). Neurology and specialist palliative care were often not co-terminus. Service provisions for neurology and specialist palliative care were also varied. For example, neurology services varied in the number and type of provided clinics and palliative care services in the settings they work in. Integration was most developed in Motor Neuron Disease (MND), e.g., joint meetings were often held, followed by Parkinsonism (made up of Parkinson’s Disease (PD), Multiple-System Atrophy (MSA) and Progressive Supranuclear Palsy (PSP), with integration being more developed for MSA and PSP) and least in Multiple Sclerosis (MS), e.g., most sites had no formal links. The number of neurology patients per annum receiving specialist palliative care reflected these differences in integration (range: 9–88 MND, 3–25 Parkinsonism, and 0–5 MS). Conclusions: This mapping exercise showed heterogeneity in service provision and integration between neurology and specialist palliative care services, which varied not only between sites but also between diseases. This highlights the need and opportunities for improved models of integration, which should be rigorously tested for effectiveness

    Means to an End: An Assessment of the Status-blind Approach to Protecting Undocumented Worker Rights

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    This article applies the tenets of bureaucratic incorporation theory to an investigation of bureaucratic decision making in labor standards enforcement agencies (LSEAs), as they relate to undocumented workers. Drawing on 25 semistructured interviews with high-level officials in San Jose and Houston, I find that bureaucrats in both cities routinely evade the issue of immigration status during the claims-making process, and directly challenge employers’ attempts to use the undocumented status of their workers to deflect liability. Respondents offer three institutionalized narratives for this approach: (1) to deter employer demand for undocumented labor, (2) the conviction that the protection of undocumented workers is essential to the agency’s ability to regulate industry standards for all workers, and (3) to clearly demarcate the agency’s jurisdictional boundaries to preserve institutional autonomy and scarce resources. Within this context, enforcing the rights of undocumented workers becomes simply an institutional means to an end
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