748 research outputs found

    Exploring strong-field deviations from general relativity via gravitational waves

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    Two new observational windows have been opened to strong gravitational physics: gravitational waves, and very long baseline interferometry. This suggests observational searches for new phenomena in this regime, and in particular for those necessary to make black hole evolution consistent with quantum mechanics. We describe possible features of "compact quantum objects" that replace classical black holes in a consistent quantum theory, and approaches to observational tests for these using gravitational waves. This is an example of a more general problem of finding consistent descriptions of deviations from general relativity, which can be tested via gravitational wave detection. Simple models for compact modifications to classical black holes are described via an effective stress tensor, possibly with an effective equation of state. A general discussion is given of possible observational signatures, and of their dependence on properties of the colliding objects. The possibility that departures from classical behavior are restricted to the near-horizon regime raises the question of whether these will be obscured in gravitational wave signals, due to their mutual interaction in a binary coalescence being deep in the mutual gravitational well. Numerical simulation with such simple models will be useful to clarify the sensitivity of gravitational wave observation to such highly compact departures from classical black holes.Comment: 20 pages, 9 figures. v2: references and CERN preprint number adde

    Tentative Detection of the Nitrosylium Ion in Space

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    We report the tentative detection in space of the nitrosylium ion, NO+^+. The observations were performed towards the cold dense core Barnard 1-b. The identification of the NO+^+ JJ=2--1 line is supported by new laboratory measurements of NO+^+ rotational lines up to the JJ=8--7 transition (953207.189\,MHz), which leads to an improved set of molecular constants: B0=59597.1379(62)B_0 = 59597.1379(62)\,MHz, D0=169.428(65)D_0 = 169.428(65)\,kHz, and eQq0(N)=6.72(15)eQq_0(\textrm{N}) = -6.72(15)\,MHz. The profile of the feature assigned to NO+^+ exhibits two velocity components at 6.5 and 7.5 km s1^{-1}, with column densities of 1.5×10121.5 \times 10^{12} and 6.5×10116.5\times10^{11} cm2^{-2}, respectively. New observations of NO and HNO, also reported here, allow to estimate the following abundance ratios: XX(NO)/XX(NO+^+)511\simeq511, and XX(HNO)/XX(NO+^+)1\simeq1. This latter value provides important constraints on the formation and destruction processes of HNO. The chemistry of NO+^+ and other related nitrogen-bearing species is investigated by the means of a time-dependent gas phase model which includes an updated chemical network according to recent experimental studies. The predicted abundance for NO+^+ and NO is found to be consistent with the observations. However, that of HNO relative to NO is too high. No satisfactory chemical paths have been found to explain the observed low abundance of HNO. HSCN and HNCS are also reported here with an abundance ratio of 1\simeq1. Finally, we have searched for NNO, NO2_2, HNNO+^+, and NNOH+^+, but only upper limits have been obtained for their column density, except for the latter for which we report a tentative 3-σ\sigma detection.Comment: To appear in the Astrophysical Journal October 20, 201

    Discrimination learning with variable stimulus 'salience'.

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    BACKGROUND: In nature, sensory stimuli are organized in heterogeneous combinations. Salient items from these combinations 'stand-out' from their surroundings and determine what and how we learn. Yet, the relationship between varying stimulus salience and discrimination learning remains unclear. PRESENTATION OF THE HYPOTHESIS: A rigorous formulation of the problem of discrimination learning should account for varying salience effects. We hypothesize that structural variations in the environment where the conditioned stimulus (CS) is embedded will be a significant determinant of learning rate and retention level. TESTING THE HYPOTHESIS: Using numerical simulations, we show how a modified version of the Rescorla-Wagner model, an influential theory of associative learning, predicts relevant interactions between varying salience and discrimination learning. IMPLICATIONS OF THE HYPOTHESIS: If supported by empirical data, our model will help to interpret critical experiments addressing the relations between attention, discrimination and learning

    Risk of Food Insecurity Reflects Health Status in Adult Relatives of PreK Children – ​ Data from the STEPS Snap-Ed Research Study​

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    Background: Past research shows a correlation between household food insecurity and chronic medical conditions such as diabetes in the general U.S. population as well as metabolic syndrome-related cardiometabolic markers in Hispanic/Latino youth. Furthermore, minority status, including Hispanic/Latino identity, shows an association with low food security and diabetes. The Hunger Vital Sign (HVS) is a validated screener designed to assess risk of food insecurity within households. This study analyzes associated factors related to the screener’s 2 questions, specifically targeting PreK 4-year-old children and their household relatives. The first question assesses concern about food running out before obtaining more due to financial constraints, while the second question evaluates instances when food did not last and there was insufficient money to purchase more. Methods: The participating preschools were primarily Hispanic/Latino and nested within schools and school districts. Data were collected through household questionnaires. The frequency of food insecurity (FI) risk was measured as an ordinal variable (never, sometimes, often) and dichotomized (never vs sometimes + often). Agreement between questions was assessed using the kappa coefficient. Mixed models were employed to predict the risk of children’s BMI and the risk of relatives developing chronic disease, adjusting for age and sex. Results: The study included 828 families, with 74% reporting never experiencing food insecurity, 22% sometimes, and 4% often. The agreement between the 2 survey questions was substantial (kappa 0.80, p \u3c 0.001). Probability of FI decreased as income level and education level of parents increased. No significant associations were found between FI and children’s age, BMI, height, or the ratio of children to adults in the household. However, a positive screen using the HVS correlated with hypertension and/or diabetes in the family. Conclusion: The HVS screens for food insecurity risk and is associated with health issues in adults rather than children\u27s body weight or height. Responses to the survey’s 2 questions can provide insights into the overall health status of a household, emphasizing the intricate relationship between food insecurity, malnutrition, and various health outcomes. The presented results support planning and resource allocation strategies to reduce food insecurity in the Hispanic/Latino population

    Producción anual de Carne/HA en pastoreo rotacional en los zacates ferrer, estrella de áfrica y señal, con y sin fertilizantes, en Hueytamalco, Pue.

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    En el Centro Experimental Pecuario de Hueytamalco, Pue., se investigó en los zacates introducidos Ferrer, Cynodon dactylon; Señal, Brachiaria brizantha, y Estrella de África, Cynodon plectostachyus, su potencial de producción anual y estacional de carne. Se utilizó un diseño completamente al azar con diferente número de animales por tratamiento: 0 y 150 kg N/ha con una carga de dos y cuatro animales/ha, respectivamente. La respuesta a la fertilización fue altamente significativa, obteniendo en promedio 618 kg carne/ha en los zacates fertilizados y 325 kg carne/ha en los zacates no fertilizados. La fertilización permitió un incremento de 92% en producción de carne/ha. Los zacates Ferrer, Estrella y Señal con cuatro animales/ha y 150 kg N/ha alcanzaron en un año de pastoreo una producción de 636, 583 y 637 kg carne/ha con una ganancia diaria promedio de 437, 400 y 438 g. respectivamente, diferencias que no fueron estadísticamente significativas (

    Trends in the prevalence and distribution of HTLV-1 and HTLV-2 infections in Spain

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    <p>Abstract</p> <p>Background</p> <p>Although most HTLV infections in Spain have been found in native intravenous drug users carrying HTLV-2, the large immigration flows from Latin America and Sub-Saharan Africa in recent years may have changed the prevalence and distribution of HTLV-1 and HTLV-2 infections, and hypothetically open the opportunity for introducing HTLV-3 or HTLV-4 in Spain. To assess the current seroprevalence of HTLV infection in Spain a national multicenter, cross-sectional, study was conducted in June 2009.</p> <p>Results</p> <p>A total of 6,460 consecutive outpatients attending 16 hospitals were examined. Overall, 12% were immigrants, and their main origin was Latin America (4.9%), Africa (3.6%) and other European countries (2.8%). Nine individuals were seroreactive for HTLV antibodies (overall prevalence, 0.14%). Evidence of HTLV-1 infection was confirmed by Western blot in 4 subjects (prevalence 0.06%) while HTLV-2 infection was found in 5 (prevalence 0.08%). Infection with HTLV types 1, 2, 3 and 4 was discarded by Western blot and specific PCR assays in another two specimens initially reactive in the enzyme immunoassay. All but one HTLV-1 cases were Latin-Americans while all persons with HTLV-2 infection were native Spaniards.</p> <p>Conclusions</p> <p>The overall prevalence of HTLV infections in Spain remains low, with no evidence of HTLV-3 or HTLV-4 infections so far.</p

    Symmetry breaking perturbations and strange attractors

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    The asymmetrically forced, damped Duffing oscillator is introduced as a prototype model for analyzing the homoclinic tangle of symmetric dissipative systems with \textit{symmetry breaking} disturbances. Even a slight fixed asymmetry in the perturbation may cause a substantial change in the asymptotic behavior of the system, e.g. transitions from two sided to one sided strange attractors as the other parameters are varied. Moreover, slight asymmetries may cause substantial asymmetries in the relative size of the basins of attraction of the unforced nearly symmetric attracting regions. These changes seems to be associated with homoclinic bifurcations. Numerical evidence indicates that \textit{strange attractors} appear near curves corresponding to specific secondary homoclinic bifurcations. These curves are found using analytical perturbational tools

    Let’s sculpt it! Experiencing the role of context in coaching

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    This exercise aims to familiarize students with the under-discussed topic of the role of context in coaching through a physical activity. It consists of a Group Sculpture – a combination of Socio-drama, Systemic Constellation, Social Presencing Theater – drawing from a coaching case of an ethical dilemma, using the placement and arrangement of participants to represent the stakeholders and context (economic, legal, sociological, etc.). The visual and embodied representation aims to raise awareness and develop understanding of the invisible, but often felt contextual factors at play in coaching, to generate reflection about their influence, and to offer insights on how to identify and embrace them. This activity is primarily aimed for coaching educators and supervisors, but a slightly adapted version could expand its benefits to a more general audience of managers and leaders
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