12,021 research outputs found
Antidepressant drugs and the response in the placebo group: the real problem lies in our understanding of the issue
In a recent paper, Horder and colleagues (Horder et al., 2010, J Psychopharmacol 25: 1277ā1288) have suggested that the mainproblem in the Kirsch analysis is methodological. We argue that the results are similar irrespective of the method used. In our opinion the data suggest that placebo and drug effects are non-additive: antidepressants act independently of depression severity, while the placebo effect is present only in milder cases. While the response in the placebo group is due to unstable ānoiseā and āartefactsā, the medication effect is reliable, valid and stable
Covariant Canonical Gauge theory of Gravitation resolves the Cosmological Constant Problem
The covariant canonical transformation theory applied to the relativistic
theory of classical matter fields in dynamic space-time yields a new (first
order) gauge field theory of gravitation. The emerging field equations embrace
a quadratic Riemann curvature term added to Einstein's linear equation. The
quadratic term facilitates a momentum field which generates a dynamic response
of space-time to its deformations relative to de Sitter geometry, and adds a
term proportional to the Planck mass squared to the cosmological constant. The
proportionality factor is given by a dimensionless parameter governing the
strength of the quadratic term. In consequence, Dark Energy emerges as a
balanced mix of three contributions, (A)dS curvature plus the residual vacuum
energy of space-time and matter. The Cosmological Constant Problem of the
Einstein-Hilbert theory is resolved as the curvature contribution relieves the
rigid relation between the cosmological constant and the vacuum energy density
of matter
Flow tracing fidelity of scattering aerosol in laser Doppler velocimetry
An experimental method for determinating the flow tracing fidelity of a scattering aerosol used in laser Doppler velocimeters was developed with particular reference to the subsonic turbulence measurements. The method employs the measurement of the dynamic response of a flow seeding aerosol excited by acoustic waves. The amplitude and frequency of excitation were controlled to simulate the corresponding values of fluid turbulence components. Experimental results are presented on the dynamic response of aerosols over the size range from 0.1 to 2.0 microns in diameter and over the frequency range 100 Hz to 100 kHz. It was observed that unit density spherical scatterers with diameters of 0.2 microns followed subsonic air turbulence frequency components up to 100 kHz with 98 percent fidelity
Canonical Transformation Path to Gauge Theories of Gravity
In this paper, the generic part of the gauge theory of gravity is derived,
based merely on the action principle and on the general principle of
relativity. We apply the canonical transformation framework to formulate
geometrodynamics as a gauge theory. The starting point of our paper is
constituted by the general De~Donder-Weyl Hamiltonian of a system of scalar and
vector fields, which is supposed to be form-invariant under (global) Lorentz
transformations. Following the reasoning of gauge theories, the corresponding
locally form-invariant system is worked out by means of canonical
transformations. The canonical transformation approach ensures by construction
that the form of the action functional is maintained. We thus encounter amended
Hamiltonian systems which are form-invariant under arbitrary spacetime
transformations. This amended system complies with the general principle of
relativity and describes both, the dynamics of the given physical system's
fields and their coupling to those quantities which describe the dynamics of
the spacetime geometry. In this way, it is unambiguously determined how spin-0
and spin-1 fields couple to the dynamics of spacetime.
A term that describes the dynamics of the free gauge fields must finally be
added to the amended Hamiltonian, as common to all gauge theories, to allow for
a dynamic spacetime geometry. The choice of this "dynamics Hamiltonian" is
outside of the scope of gauge theory as presented in this paper. It accounts
for the remaining indefiniteness of any gauge theory of gravity and must be
chosen "by hand" on the basis of physical reasoning. The final Hamiltonian of
the gauge theory of gravity is shown to be at least quadratic in the conjugate
momenta of the gauge fields -- this is beyond the Einstein-Hilbert theory of
General Relativity.Comment: 16 page
The financial impact of ISO 9000 certification in the United States: an empirical analysis.
The ISO 9000 series of quality management systems standards, introduced in 1986, has been adopted at over 560,000 locations worldwide. Anecdotal evidence suggests that firms can achieve internal benefits such as quality or productivity improvements or that certification can help firms maintain or increase their market share, or both. Others argue that the standard is too generic to cause performance improvement but can be seen as a signal of good management. In this paper, we track financial performance from 1987 to 1997 of all publicly traded ISO 9000 certified manufacturing firms in the United States with SIC codes 2000ā3999, and test whether ISO 9000 certification leads to productivity improvements, market benefits, and improved financial performance. We employ event-study methods, matching each certified firm to a control group of one or more noncertified firms in the same industry with similar precertification size and/or return on assets. We find that firmsā decision to seek their first ISO 9000 certification was indeed followed by significant abnormal improvements in financial performance, though the exact timing and magnitude of this effect depend on the specification of the control group. Three years after certification, the certified firms do display strongly significant abnormal performance under all control-group specifications. The degree to which the precise results vary across control-group specifications indicates that event studies should always include extensive sensitivity analysis, for instance matching by size and performance separately and jointly, using both single firms and portfolios as controls.ISO 9000; Quality management; Standards; Financial; Empirical; Event study; Compustat;
The NCAA\u27s rise to absolute power and confronting its distortion of amateurism
This paper examines the progression of the intercollegiate athletic space, from a small regatta in 1852 to the massive athletic environment we know now in contemporary society. It finds the National Collegiate Athletic Association snared in a trap of circular logic that has been closing in on it since its conception, as it has defined collegiate athletes as amateurs and then proceeded to argue for amateur status for those athletes because of the definition that it wrote. This paper concludes in its final two chapters, after analyzing the recent Supreme Court case NCAA v. Alston, and the Name, Image, and Likeness legalization that followed, that the NCAA has recently taken a seismic blow to its authoritarian regime over collegiate athletics. It also fills an understudied yet extremely important gap in the historiography, due to its analysis of modern NIL deals and the transfer portal ā two crucial pieces of contemporary collegiate athletics that have not yet come under academic study because they are so recent. This study finds that the intercollegiate athletic landscape is likely changed forever, and furthermore, that this change is for the better
Evolution of the relationship between the U.S. financial accounting standards and the international accounting standard setters: 1973-2008
Utilizing archival materials as well as personal interviews and correspondence with personnel of the Financial Accounting Standards Board (FASB) and International Accounting Standards Committee /Board (IASC/B), including former Board chairmen and staff members, this paper examines the development of the working relationships between the FASB and the IASC/B from their earliest interactions in 1973 through the transformation of the IASC into the IASB and the Convergence Program rooted in the 2002 Norwalk Agreement up to 2008
Many cliques in bounded-degree hypergraphs
Recently Chase determined the maximum possible number of cliques of size t in a graph on n vertices with given maximum degree. Soon afterward, Chakraborti and Chen answered the version of this question in which we ask that the graph have m edges and fixed maximum degree (without imposing any constraint on the number of vertices). In this paper we address these problems on hypergraphs. For s-graphs with s ā„ 3 a number of issues arise that do not appear in the graph case. For instance, for general s-graphs we can assign degrees to any i-subset of the vertex set with 1 ā¤ i ā¤ s ā 1.
We establish bounds on the number of t-cliques in an s-graph H with i-degree bounded by Ī in three contexts: H has n vertices; H has m (hyper)edges; and (generalizing the previous case) H has a fixed number p of u-cliques for some u with s ā¤ u ā¤ t. When Ī is of a special form we characterize the extremal s-graphs and prove that the bounds are tight. These extremal examples are the shadows of either Steiner systems or packings. On the way to proving our uniqueness results, we extend results of FĆ¼redi and Griggs on uniqueness in Kruskal-Katona from the shadow case to the clique case
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