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Search Results: 1 - 10 of 3351 matches for " Allen Everett "
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Time travel paradoxes, path integrals, and the many worlds interpretation of quantum mechanics
Allen Everett
Physics , 2004, DOI: 10.1103/PhysRevD.69.124023
Abstract: We consider two approaches to evading paradoxes in quantum mechanics with closed timelike curves (CTCs). In a model similar to Politzer's, assuming pure states and using path integrals, we show that the problems of paradoxes and of unitarity violation are related; preserving unitarity avoids paradoxes by modifying the time evolution so that improbable events bewcome certain. Deutsch has argued, using the density matrix, that paradoxes do not occur in the "many worlds interpretation". We find that in this approach account must be taken of the resolution time of the device that detects objects emerging from a wormhole or other time machine. When this is done one finds that this approach is viable only if macroscopic objects traversing a wormhole interact with it so strongly that they are broken into microscopic fragments.
Magnetic Fields from Phase Transitions
Mark Hindmarsh,Allen Everett
Physics , 1997, DOI: 10.1103/PhysRevD.58.103505
Abstract: The generation of primordial magnetic fields from cosmological phase transitions is discussed, paying particular attention to the electroweak transition and to the various definitions of the `average' field that have been put forward. It is emphasised that only the volume average has dynamical significance as a seed for galactic dynamos. On rather general grounds of causality and energy conservation, it is shown that, in the absence of MHD effects that transfer power in the magnetic field from small to large scales, processes occurring at the electroweak transition cannot generate fields stronger than $10^{-20}$ Gauss on a scale of 0.5 Mpc. However, it is implausible that this upper bound could ever be reached, as it would require all the energy in the Universe to be turned into a magnetic field coherent at the horizon scale. Non-linear MHD effects seem therefore to be necessary if the electroweak transition is to create a primordial seed field.
Hepatoma derived growth factor binds DNA through the N-terminal PWWP domain
Jun Yang, Allen D Everett
BMC Molecular Biology , 2007, DOI: 10.1186/1471-2199-8-101
Abstract: Using chromatin immunoprecipitation (ChIP) of human DNA, we isolated 10 DNA sequences sharing a conserved ~200 bp element. Homology analysis identified the binding sequences as a motif within the promoter of the SMYD1 gene, a HDGF target gene. Electrophoretic Mobility Shift Assays (EMSA) confirmed the binding of HDGF to this conserved sequence. As a result, an 80 bp conserved sequence located in the SMYD1 promoter bound GST-HDGF tightly. The binding core sequence for HDGF was narrowed down to 37 bp using a deletion mapping strategy from both the 5' and 3' ends. Moreover, ChIP and DNase I footprinting analysis revealed that HDGF binds this 80 bp DNA fragment specifically. Functionally overexpression of HDGF represses a reporter gene which is controlled by an SV-40 promoter containing the 80 bp DNA element. Using serial truncations of GST-HDGF, we mapped the DNA binding domain of HDGF to the N-terminal PWWP domain.HDGF is a DNA binding protein, binds DNA specifically, and prefers a minimum of 37 bp long DNA fragment. The N-terminal PWWP domain of HDGF is required for DNA binding. HDGF exerts its transcription repressive effect through binding to a conserved DNA element in the promoter of target genes.Hepatoma derived growth factor (HDGF) is a nuclear protein with mitogenic activity [1,2]. It is highly expressed in developing heart and fetal gut [3]; and re-expressed in vascular smooth muscle cells in vivo after vascular injury [4,5], suggesting that it plays an important role in cardiovascular growth and differentiation. Recently by a number of investigators, HDGF was found to be tumorigenic and a prognostic factor for a number of cancers [6-11]. We have discovered that HDGF functions as a transcriptional repressor, suggesting that HDGF may physiologically regulate cellular proliferation and differentiation by repressing the genes governing terminal differentiation (submitted). However using NMR structural analyses, it is unclear if HDGF is a direct DNA binding protei
Can a circulating light beam produce a time machine?
Ken D. Olum,Allen Everett
Physics , 2004, DOI: 10.1007/s10702-005-7127-4
Abstract: In a recent paper, Mallett found a solution of the Einstein equations in which closed timelike curves (CTC's) are present in the empty space outside an infinitely long cylinder of light moving in circular paths around an axis. Here we show that, for physically realistic energy densities, the CTC's occur at distances from the axis greater than the radius of the visible universe by an immense factor. We then show that Mallett's solution has a curvature singularity on the axis, even in the case where the intensity of the light vanishes. Thus it is not the solution one would get by starting with Minkowski space and establishing a cylinder of light.
A Superluminal Subway: The Krasnikov Tube
Allen E. Everett,Thomas A. Roman
Physics , 1997, DOI: 10.1103/PhysRevD.56.2100
Abstract: The ``warp drive'' metric recently presented by Alcubierre has the problem that an observer at the center of the warp bubble is causally separated from the outer edge of the bubble wall. Hence such an observer can neither create a warp bubble on demand nor control one once it has been created. In addition, such a bubble requires negative energy densities. One might hope that elimination of the first problem might ameliorate the second as well. We analyze and generalize a metric, originally proposed by Krasnikov for two spacetime dimensions, which does not suffer from the first difficulty. As a consequence, the Krasnikov metric has the interesting property that although the time for a one-way trip to a distant star cannot be shortened, the time for a round trip, as measured by clocks on Earth, can be made arbitrarily short. In our four dimensional extension of this metric, a ``tube'' is constructed along the path of an outbound spaceship, which connects the Earth and the star. Inside the tube spacetime is flat, but the light cones are opened out so as to allow superluminal travel in one direction. We show that, although a single Krasnikov tube does not involve closed timelike curves, a time machine can be constructed with a system of two non-overlapping tubes. Furthermore, it is demonstrated that Krasnikov tubes, like warp bubbles and traversable wormholes, also involve unphysically thin layers of negative energy density, as well as large total negative energies, and therefore probably cannot be realized in practice.
Mitotic phosphorylation activates hepatoma-derived growth factor as a mitogen
Allen D Everett, Jun Yang, Monzur Rahman, Pratima Dulloor, David L Brautigan
BMC Cell Biology , 2011, DOI: 10.1186/1471-2121-12-15
Abstract: We found that HDGF in primary mouse aortic vascular smooth muscle cells (VSMC) was phosphorylated. Wild type HDGF was phosphorylated in asynchronous cells and substitution of S103, S165 and S202 to alanine each demonstrated a decrease in HDGF phosphorylation. A phospho-S103 HDGF specific antibody was developed and demonstrated mitosis-specific phosphorylation. HDGF-S103A was not mitogenic and FACS analysis demonstrated a G2/M arrest in HDGF-S103A expressing cells, whereas cells expressing HDGF-S103D showed cell cycle progression. Nocodazole arrest increased S103 phosphorylation from 1.6% to 29% (P = 0.037).Thus, HDGF is a phosphoprotein and phosphorylation of S103 is mitosis related and required for its function as a mitogen. We speculate that cell cycle regulated phosphorylation of HDGF may play an important role in vascular cell proliferation.HDGF [GenBank: NM_004494] is a heparin binding protein originally isolated from conditioned media of a human hepatoma (HuH-7) cell line. HDGF was subsequently shown to be a mitogen for many cell types with nuclear localization necessary for its mitogenic activity [1-6]. Expression of HDGF is developmentally regulated in at least the renal, cardiovascular and pulmonary systems [1,3,7] and re-expressed at least in the both the lung [8] and the arterial wall in response to injury [9], suggesting a role in tissue repair. HDGF has also been identified at least as an important prognostic marker in pathologic cell growth, as it is overexpressed in a number of cancers with expression linked to a poor outcome in lung, esophageal, pancreatic and hepatic cancer [10-13].Many nuclear proteins undergo post-translational modification to regulate their activity. This is most clearly demonstrated by the cell cycle regulatory cyclin and CDK proteins which undergo both phosphorylation and dephosphorylation to regulate their activity [reviewed in [14]]. Previously we had shown by two-dimensional gel electrophoresis that HDGF in human melanoma ce
Dark Experiments: From Black Holes to Cosmic Rays  [PDF]
Allen D. Allen
Journal of Modern Physics (JMP) , 2012, DOI: 10.4236/jmp.2012.39125
Abstract: Some nagging questions in modern physics can be resolved rigorously using a basic mathematical formalism, albeit with the need to admit that non-isomorphic realities arise to various degrees in a given universe. Let U=(m', m\") be an unordered pair of distinct massive objects in different reference frames. A dark experiment is an ordering u, mv> of the elements of U, either or, exclusively, , where the left-hand member of the ordered pair is called the observer, and where there exists a 1-to-1 mapping f:{u}→{events}, mv> , such that both elements of an ordered pair in a dark experiment agree on the events that unfold in the experiment. However, since , it follows that f()≠f(). This describes non-isomorphic realities where in both elements of each ordered pair mapping two distinct sets of unfolding events will agree on their respective events. Consequently, there is an inherent limitation on what can be determined directly from experimentation. Examples arise in the context of the Hawking information paradox, relativistic time travel, and cosmic ray experiments.
State of the Art in Cardiac Intervention: A Case Report  [PDF]
Allen D. Allen
International Journal of Clinical Medicine (IJCM) , 2012, DOI: 10.4236/ijcm.2012.37112
Abstract:

The first acute myocardial infarction (MI) of an elderly male was determined through angiography to be due to an infarct of the circumflex artery. The angiogram also revealed chronic occlusion and diffuse disease of the left anterior descending artery (LAD). This had been compensated for by collateral circulation from the right coronary artery. Since the patient had no prior history of coronary artery disease, the chronic and collateralized disease of the LAD was presumed to be stable and this artery was not treated. Due to a history of aspirin intolerance a bare metal stent was implanted in the circumflex artery. Within hours after stenting the patient had a second acute MI. Despite no change in the angiogram, the EKG suggested that the LAD was the source of the second MI. Indeed, a drug-eluting stent implanted in the LAD resolved the patient’s signs and symptoms and he was discharged with a favorable outcome. The surprising second MI and the inconsistent stenting illustrate that when the unexpected occurs, there is no substitute for the judgment of a skilled clinician.

Finite Gravity: From the Big Bang to Dark Matter  [PDF]
Allen D. Allen
International Journal of Astronomy and Astrophysics (IJAA) , 2013, DOI: 10.4236/ijaa.2013.32020
Abstract:

The purpose of the present paper is to assume that the expanding spacetime of our cosmos was created by the big bang. It then follows that there exists a finite instantaneous radial extent dRU to spacetime as observed from anywhere in spacetime by comoving observers. The consequences for gravity are explored by first considering the scalar field of a central mass that defines the dynamic properties of a circular orbit for each radius RdRU under the postulate of weak equivalence. These properties include an orbital velocity and an escape velocity. For a central mass of galactic proportion, the escape velocity becomes large even at cosmological distances. By considering the dynamics of a smaller mass occupying the last orbit, we find that the established laws of physics lead to different rotation curves than they do when applied to the solar system. Since galactic rotation curves reveal the existence of dark matter, this is anticipated to have some consequences for our understanding of dark matter.

Implications of rare neurological disorders and perceptual errors in natural and synthetic consciousness  [PDF]
Allen D. Allen
World Journal of Neuroscience (WJNS) , 2013, DOI: 10.4236/wjns.2013.34031
Abstract:

Recent theories on natural and synthetic consciousness overlook the geometric structure necessary for awareness of 3-dimensional space, as strikingly illustrated by left-neglect disorder. Furthermore, awareness of 3-dimensional space entails some surprisingly tenacious optical illusions, as demonstrated by an experiment in the text. Awareness of linear time is also crucial and complex. As a consequence, synthetic consciousness cannot be realized by simply intercomnecting a large number of electronic circuits constructed from ordinary chips and transistors. Since consciousness is a subjective experience, there is no sufficient condition for consciousness that can be experimentally confirmed. The most we can hope for is agreement on the necessary conditions for consciousness. Toward that end, this paper reviews some relevant clinical phenomena. 

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