33 research outputs found

    Alfven Wave Generation by means of High Orbital Injection of Barium Cloud in Magnetosphere

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    An analysis of the Alfven wave generation associated with the barium vapor release at altitudes ~ 5.2 Earth's radii (ER) in the magnetosphere is presented. Such injections were executed in G-8 and G-10 experiments of the Combined Radiation and Radiation Effects Satellite (CRRES) mission. It is shown that the generation of Alfven waves is possible during the total time of plasma expansion. The maximum intensity of these waves corresponds to the time of complete retardation of the diamagnetic cavity created by the expansion of plasma cloud. The Alfven wave exhibits a form of an impulse with an effective frequency ~ 0.03-0.05 Hz. Due to the background conditions and wave frequency, the wave mainly oscillates along the geomagnetic field between the mirror reflection points situated at ~ 0.7 ER. The wave amplitude is sufficient to the generation of plasma instabilities and longitudinal electric field, and to an increase in the longitudinal energy of electrons to ~ 1 keV. These processes are the most probable for altitudes ~ 1 ER. The auroral kilometric radiation (AKR) at frequencies ~ 100 kHz is associated with these accelerated electrons. The acceleration of electrons and AKR can be observed almost continuously during the first minute and then from time to time with pauses about 35-40 s till 6-8 min after the release. The betatron acceleration of electrons at the recovery of the geomagnetic field is also discussed. This mechanism could be responsible for the acceleration of electrons resulting in the aurorae and ultra short radio wave storm at frequencies 50-300 MHz observed at the 8-10th min after the release.Comment: Presented at COSPAR 200

    Pulsar Timing and its Application for Navigation and Gravitational Wave Detection

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    Pulsars are natural cosmic clocks. On long timescales they rival the precision of terrestrial atomic clocks. Using a technique called pulsar timing, the exact measurement of pulse arrival times allows a number of applications, ranging from testing theories of gravity to detecting gravitational waves. Also an external reference system suitable for autonomous space navigation can be defined by pulsars, using them as natural navigation beacons, not unlike the use of GPS satellites for navigation on Earth. By comparing pulse arrival times measured on-board a spacecraft with predicted pulse arrivals at a reference location (e.g. the solar system barycenter), the spacecraft position can be determined autonomously and with high accuracy everywhere in the solar system and beyond. We describe the unique properties of pulsars that suggest that such a navigation system will certainly have its application in future astronautics. We also describe the on-going experiments to use the clock-like nature of pulsars to "construct" a galactic-sized gravitational wave detector for low-frequency (f_GW ~1E-9 - 1E-7 Hz) gravitational waves. We present the current status and provide an outlook for the future.Comment: 30 pages, 9 figures. To appear in Vol 63: High Performance Clocks, Springer Space Science Review

    Dynamics of Fermionic Four-Wave Mixing

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    We study the dynamics of a beam of fermions diffracted off a density grating formed by fermionic atoms in the limit of a large grating. An exact description of the system in terms of particle-hole operators is developed. We use a combination of analytical and numerical methods to quantitatively explore the Raman-Nath and the Bragg regimes of diffraction. We discuss the limits in diffraction efficiency resulting from the dephasing of the grating due the distribution of energy states occupied by the fermions. We propose several methods to overcome these limits, including the novel technique of ``atom echoes''.Comment: 8 pages, 7 figure

    The bank lending channel: an empirical assessment of measures to stimulate bank lending in the European Union

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    This thesis first examines the role of banks in the transmission mechanism of monetary policy by focusing on the eight European new member States of Central and Eastern Europe over the 2004-2013 period. We specifically investigate the influence of monetary policy changes on bank lending activity and if this potential influence is contingent on bank characteristics, such as banks’ size, capital, liquidity, risk factor and market power. Moreover, we focus on the prospective role of banks in the monetary policy transmission mechanism in order to reveal any clear trends in banks’ lending behaviour during the 2008-2011 financial crisis. Secondly, we investigate the impact of a protracted period of low monetary policy rates on loosening of banks’ credit standards regarding enterprises, households and consumer loans through concentrating on the nine Eurozone countries involved since the initiation of the Euro area Bank Lending Survey in the three distinct time frames of pre- (2002Q4-2008Q3), mid- (2008Q4-2010Q4) and post- (2011Q1-2014:Q4) financial crisis. Furthermore, we test the fundamental concept of the risk taking channel by examining excessive risk-taking behaviour by banks in stressed vs. non-stressed countries of the Eurozone. In an additional analysis, the efficacy of the European Central Bank’s 3 year Long-Term Refinancing Operations is evaluated in great depth in order to determine whether banks’ credit standards have been softened and the degree to which demand for loans has increased. Thirdly, we explore the financing structure of bank lending constrained Small and Medium Sized Enterprises in the eleven Eurozone countries by utilising firm-level data over the period of 2009 to 2014. We estimate if bank lending constrained firms demonstrate relatively more usage or requests for alternative financing. Additionally, a comprehensive investigation is presented by unveiling the impact and determinants of various financing constraints including credit lines, bank loans, trade credit and other lending on Eurozone firms. Furthermore, the notion of discouraged borrowers originally formulated by Kon and Storey (2003) is empirically evaluated. Finally, we present the conclusion of our research by further outlining its limitations and prospective scope for future studie

    Ageing affects subtelomeric DNA methylation in blood cells from a large European population enrolled in the MARK-AGE study

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    Ageing leaves characteristic traces in the DNA methylation make-up of the genome. However, the importance of DNA methylation in ageing remains unclear. The study of subtelomeric regions could give promising insights into this issue. Previously reported associations between susceptibility to age-related diseases and epigenetic instability at subtelomeres suggest that the DNA methylation profile of subtelomeres undergoes remodelling during ageing. In the present work, this hypothesis has been tested in the context of the European large-scale project MARK-AGE. In this cross-sectional study, we profiled the DNA methylation of chromosomes 5 and 21 subtelomeres, in more than 2000 age-stratified women and men recruited in eight European countries. The study included individuals from the general population as well as the offspring of nonagenarians and Down syndrome subjects, who served as putative models of delayed and accelerated ageing, respectively. Significant linear changes of subtelomeric DNA methylation with increasing age were detected in the general population, indicating that subtelomeric DNA methylation changes are typical signs of ageing. Data also show that, compared to the general population, the dynamics of age-related DNA methylation changes are attenuated in the offspring of centenarian, while they accelerate in Down syndrome individuals. This result suggests that subtelomeric DNA methylation changes reflect the rate of ageing progression. We next attempted to trace the age-related changes of subtelomeric methylation back to the influence of diverse variables associated with methylation variations in the population, including demographics, dietary/health habits and clinical parameters. Results indicate that the effects of age on subtelomeric DNA methylation are mostly independent of all other variables evaluated.Molecular Epidemiolog

    Reforming Watershed Restoration: Science in Need of Application and Applications in Need of Science

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    TRY plant trait database – enhanced coverage and open access

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    Plant traits—the morphological, anatomical, physiological, biochemical and phenological characteristics of plants—determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait‐based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits—almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

    Risk profiles and one-year outcomes of patients with newly diagnosed atrial fibrillation in India: Insights from the GARFIELD-AF Registry.

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    BACKGROUND: The Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF) is an ongoing prospective noninterventional registry, which is providing important information on the baseline characteristics, treatment patterns, and 1-year outcomes in patients with newly diagnosed non-valvular atrial fibrillation (NVAF). This report describes data from Indian patients recruited in this registry. METHODS AND RESULTS: A total of 52,014 patients with newly diagnosed AF were enrolled globally; of these, 1388 patients were recruited from 26 sites within India (2012-2016). In India, the mean age was 65.8 years at diagnosis of NVAF. Hypertension was the most prevalent risk factor for AF, present in 68.5% of patients from India and in 76.3% of patients globally (P < 0.001). Diabetes and coronary artery disease (CAD) were prevalent in 36.2% and 28.1% of patients as compared with global prevalence of 22.2% and 21.6%, respectively (P < 0.001 for both). Antiplatelet therapy was the most common antithrombotic treatment in India. With increasing stroke risk, however, patients were more likely to receive oral anticoagulant therapy [mainly vitamin K antagonist (VKA)], but average international normalized ratio (INR) was lower among Indian patients [median INR value 1.6 (interquartile range {IQR}: 1.3-2.3) versus 2.3 (IQR 1.8-2.8) (P < 0.001)]. Compared with other countries, patients from India had markedly higher rates of all-cause mortality [7.68 per 100 person-years (95% confidence interval 6.32-9.35) vs 4.34 (4.16-4.53), P < 0.0001], while rates of stroke/systemic embolism and major bleeding were lower after 1 year of follow-up. CONCLUSION: Compared to previously published registries from India, the GARFIELD-AF registry describes clinical profiles and outcomes in Indian patients with AF of a different etiology. The registry data show that compared to the rest of the world, Indian AF patients are younger in age and have more diabetes and CAD. Patients with a higher stroke risk are more likely to receive anticoagulation therapy with VKA but are underdosed compared with the global average in the GARFIELD-AF. CLINICAL TRIAL REGISTRATION-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01090362

    Clinical characteristics and cardiovascular magnetic resonance findings in stress (takotsubo) cardiomyopathy

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    Context: Stress cardiomyopathy (SC) is a transient form of acute heart failure triggered by stressful events and associated with a distinctive left ventricular (LV) contraction pattern. Various aspects of its clinical profile have been described in small single-center populations, but larger, multicenter data sets have been lacking so far. Furthermore, it remains difficult to quickly establish diagnosis on admission. Objectives: To comprehensively define the clinical spectrum and evolution of SC in a large population, including tissue characterization data from cardiovascular magnetic resonance (CMR) imaging; and to establish a set of CMR criteria suitable for diagnostic decision making in patients acutely presenting with suspected SC. Design, Setting, and Patients: Prospective study conducted at 7 tertiary care centers in Europe and North America between January 2005 and October 2010 among 256 patients with SC assessed at the time of presentation as well as 1 to 6 months after the acute event. Main Outcome Measures: Complete recovery of LV dysfunction. Results: Eighty-one percent of patients (n = 207) were postmenopausal women, 8% (n = 20) were younger women (aged </=50 years), and 11% (n = 29) were men. A stressful trigger could be identified in 182 patients (71%). Cardiovascular magnetic resonance imaging data (available for 239 patients [93%]) revealed 4 distinct patterns of regional ventricular ballooning: apical (n = 197 [82%]), biventricular (n = 81 [34%]), midventricular (n = 40 [17%]), and basal (n = 2 [1%]). Left ventricular ejection fraction was reduced (48% [SD, 11%]; 95% confidence interval [CI], 47%-50%) in all patients. Stress cardiomyopathy was accurately identified by CMR using specific criteria: a typical pattern of LV dysfunction, myocardial edema, absence of significant necrosis/fibrosis, and markers for myocardial inflammation. Follow-up CMR imaging showed complete normalization of LV ejection fraction (66% [SD, 7%]; 95% CI, 64%-68%) and inflammatory markers in the absence of significant fibrosis in all patients. Conclusions: The clinical profile of SC is considerably broader than reported previously. Cardiovascular magnetic resonance imaging at the time of initial clinical presentation may provide relevant functional and tissue information that might aid in the establishment of the diagnosis of SC
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