690 research outputs found
Models of OH Maser Variations in U Her
Arecibo spectra of the mainline OH maser emission from U Her over more than a
decade show variations of the OH emission over these time scales. These
observations are combined with high spatial resolution VLBA maps to investigate
the causes of the variations in the velocities of the maser components. Global
properties of the dust shell, such as accelerations, variations in the pump and
shell-wide magnetic field changes are examined as possibilities, and
eliminated. A possible solution to the problem involving plasma turbulence and
the local magnetic field is introduced, and the relevant time scales of the
turbulence are calculated. The turbulent velocity field yields time scales of
the turbulence are calculated. The turbulent velocity field yields time scales
that are too long (of order centuries), while the turbulent magnetic field
produces variations on appropriate time scales of a few years. A line-of-sight
model of the turbulence is developed and investigated. The complete exploration
of this solution requires extensive theoretical and observational work.
Possible avenues of investigation of the plasma turbulence model are presented.Comment: 23 pages, 17 figures, ApJ: accepted Sept, 199
Legal determinants of external finance revisited : the inverse relationship between investor protection and societal well-being
This paper investigates relationships between corporate governance traditions and quality of life as measured by a number of widely reported indicators. It provides an empirical analysis of indicators of societal health in developed economies using a classification based on legal traditions. Arguably the most widely cited work in the corporate governance literature has been the collection of papers by La Porta et al. which has shown, inter alia, statistically significant relationships between legal traditions and various proxies for investor protection. We show statistically significant relationships between legal traditions and various proxies for societal health. Our comparative evidence suggests that the interests of investors may not be congruent with the interests of wider society, and that the criteria for judging the effectiveness of approaches to corporate governance should not be restricted to financial metrics
The Nature of Composite LINER/HII Galaxies, As Revealed from High-Resolution VLA Observations
A sample of 37 nearby galaxies displaying composite LINER/HII and pure HII
spectra was observed with the VLA in an investigation of the nature of their
weak radio emission. The resulting radio contour maps overlaid on optical
galaxy images are presented here, together with an extensive literature list
and discussion of the individual galaxies. Radio morphological data permit
assessment of the ``classical AGN'' contribution to the global activity
observed in these ``transition'' LINER galaxies. One in five of the latter
objects display clear AGN characteristics: these occur exclusively in
bulge-dominated hosts.Comment: 31 pages, 27 figures, accepted by ApJ
Modelling Conformational Flexibility in a Spectrally Addressable Molecular Multi-Qubit Model System
Dipolar coupled multi-spin systems have the potential to be used as molecular qubits. Herein we report the synthesis of a molecular multi-qubit model system with three individually addressable, weakly interacting, spin (Formula presented.) centres of differing g-values. We use pulsed Electron Paramagnetic Resonance (EPR) techniques to characterise and separately address the individual electron spin qubits; CuII, Cr7Ni ring and a nitroxide, to determine the strength of the inter-qubit dipolar interaction. Orientation selective Relaxation-Induced Dipolar Modulation Enhancement (os-RIDME) detecting across the CuII spectrum revealed a strongly correlated CuII-Cr7Ni ring relationship; detecting on the nitroxide resonance measured both the nitroxide and CuII or nitroxide and Cr7Ni ring correlations, with switchability of the interaction based on differing relaxation dynamics, indicating a handle for implementing EPR-based quantum information processing (QIP) algorithms
The Rachel Carson Letters and the Making of Silent Spring
Environment, conservation, green, and kindred movements look back to Rachel Carsonâs 1962 book Silent Spring as a milestone. The impact of the book, including on government, industry, and civil society, was immediate and substantial, and has been extensively described; however, the provenance of the book has been less thoroughly examined. Using Carsonâs personal correspondence, this paper reveals that the primary source for Carsonâs book was the extensive evidence and contacts compiled by two biodynamic farmers, Marjorie Spock and Mary T. Richards, of Long Island, New York. Their evidence was compiled for a suite of legal actions (1957-1960) against the U.S. Government and that contested the aerial spraying of dichlorodiphenyltrichloroethane (DDT). During Rudolf Steinerâs lifetime, Spock and Richards both studied at Steinerâs Goetheanum, the headquarters of Anthroposophy, located in Dornach, Switzerland. Spock and Richards were prominent U.S. anthroposophists, and established a biodynamic farm under the tutelage of the leading biodynamics exponent of the time, Dr. Ehrenfried Pfeiffer. When their property was under threat from a government program of DDT spraying, they brought their case, eventually lost it, in the process spent US$100,000, and compiled the evidence that they then shared with Carson, who used it, and their extensive contacts and the trial transcripts, as the primary input for Silent Spring. Carson attributed to Spock, Richards, and Pfeiffer, no credit whatsoever in her book. As a consequence, the organics movement has not received the recognition, that is its due, as the primary impulse for Silent Spring, and it is, itself, unaware of this provenance
The effects of remote ischaemic preconditioning on coronary artery function in patients with stable coronary artery disease
Background: Remote ischaemic preconditioning (RIPC) is a cardioprotective intervention invoking intermittent
periods of ischaemia in a tissue or organ remote from the heart. The mechanisms of this effect are incompletely
understood. We hypothesised that RIPC might enhance coronary vasodilatation by an endothelium-dependent
mechanism.
Methods: We performed a prospective, randomised, sham-controlled, blinded clinical trial. Patients with stable
coronary artery disease (CAD) undergoing elective invasive management were prospectively enrolled,
and randomised to RIPC or sham (1:1) prior to angiography. Endothelial-dependent vasodilator function
was assessed in a non-target coronary artery with intracoronary infusion of incremental acetylcholine doses
(10â6
, 10â5
, 10â4 mol/l). Venous blood was sampled pre- and post-RIPC or sham, and analysed for circulating
markers of endothelial function. Coronary luminal diameter was assessed by quantitative coronary angiography.
The primary outcome was the between-group difference in the mean percentage change in coronary luminal diameter
following the maximal acetylcholine dose (Clinicaltrials.gov identifier: NCT02666235).
Results: 75 patients were enrolled. Following angiography, 60 patients (mean ± SD age 57.5 ± 8.5 years; 80%
male) were eligible and completed the protocol (n = 30 RIPC, n = 30 sham). The mean percentage change in
coronary luminal diameter was â13.3 ± 22.3% and â2.0 ± 17.2% in the sham and RIPC groups respectively
(difference 11.32%, 95%CI: 1.2â 21.4, p = 0.032). This remained significant when age and sex were included as
covariates (difference 11.01%, 95%CI: 1.01â 21.0, p = 0.035). There were no between-group differences in
endothelial-independent vasodilation, ECG parameters or circulating markers of endothelial function.
Conclusions: RIPC attenuates the extent of vasoconstriction induced by intracoronary acetylcholine infusion. This
endothelium-dependent mechanism may contribute to the cardioprotective effects of RIP
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The Modern Corporation Statement on Accounting
A number of regulatory initiatives on the national, international and EU levels both foster and fortify the principle of Maximizing Shareholder Value (MSV) in corporate governance. This tendency can be clearly seen in such areas as financial accounting standards and various soft and hard law initiatives pertaining to corporate governance that have flourished in recent decades. These have created a new type of accountability for managers of listed corporations as will be exemplified below. One of the most important regulatory changes over this period was when the EU opted for International Financial Reporting Standards (IFRS) as a basis for financial reporting for the accounts of all listed, EU-based corporations in 2005. These accounting standards, amounting to quasi legislation, are issued by a private sector body â the International Accounting Standards Board (IASB). Other important regulatory changes include the various national âcorporate governance codesâ that have mushroomed since the early 1990s. Although such codes pertain to member states, the EU remains the main body prescribing most new hard-law corporate governance regulation within the union, for example, by means of the 13 company law directives issued so far
On the possibility of magneto-structural correlations: detailed studies of di-nickel carboxylate complexes
A series of water-bridged dinickel complexes of the general formula [Ni<sub>2</sub>(Ό<sub>2</sub>-OH<sub>2</sub>)(Ό2-
O<sub>2</sub>C<sup>t</sup>Bu)<sub>2</sub>(O<sub>2</sub>C<sup>t</sup>Bu)2(L)(L0)] (L = HO<sub>2</sub>C<sup>t</sup>Bu, L0 = HO<sub>2</sub>C<sup>t</sup>Bu (1), pyridine (2),
3-methylpyridine (4); L = L0 = pyridine (3), 3-methylpyridine (5)) has been synthesized
and structurally characterized by X-ray crystallography. The magnetic properties
have been probed by magnetometry and EPR spectroscopy, and detailed measurements
show that the axial zero-field splitting, D, of the nickel(ii) ions is on the same order as
the isotropic exchange interaction, J, between the nickel sites. The isotropic exchange
interaction can be related to the angle between the nickel centers and the bridging
water molecule, while the magnitude of D can be related to the coordination sphere at
the nickel sites
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