258 research outputs found
Winterberg's conjectured breaking of the superluminal quantum correlations over large distances
We elaborate further on a hypothesis by Winterberg that turbulent
fluctuations of the zero point field may lead to a breakdown of the
superluminal quantum correlations over very large distances. A phenomenological
model that was proposed by Winterberg to estimate the transition scale of the
conjectured breakdown, does not lead to a distance that is large enough to be
agreeable with recent experiments. We consider, but rule out, the possibility
of a steeper slope in the energy spectrum of the turbulent fluctuations, due to
compressibility, as a possible mechanism that may lead to an increased
lower-bound for the transition scale. Instead, we argue that Winterberg
overestimated the intensity of the ZPF turbulent fluctuations. We calculate a
very generous corrected lower bound for the transition distance which is
consistent with current experiments.Comment: 7 pages, submitted to Int. J. Theor. Phy
A lactate and formate transporter in the intraerythrocytic malaria parasite, Plasmodium falciparum
The intraerythrocytic malaria parasite relies primarily on glycolysis to fuel its rapid growth and reproduction. The major byproduct of this metabolism, lactic acid, is extruded into the external medium. In this study, we show that the human malaria parasite Plasmodium falciparum expresses at its surface a member of the microbial formate-nitrite transporter family (PfFNT), which, when expressed in Xenopus laevis oocytes, transports both formate and lactate. The transport characteristics of PfFNT in oocytes (pH-dependence, inhibitor-sensitivity and kinetics) are similar to those of the transport of lactate and formate across the plasma membrane of mature asexual-stage P. falciparum trophozoites, consistent with PfFNT playing a major role in the efflux of lactate and hence in the energy metabolism of the intraerythrocytic parasite.This work was supported by grants from the Australian National Health and Medical
Research Council (NHMRC; 316933 and 525428 to K.K. and 1007035 to R.E.M.), and by
the L’Ore´al Australia For Women in Science programme (R.E.M.). A.M.L. was supported
by an NHMRC Overseas Biomedical Fellowship (585519) and R.E.M. was supported by
NHMRC Australian Biomedical Fellowships (520320 and 1053082)
Sheared Flow As A Stabilizing Mechanism In Astrophysical Jets
It has been hypothesized that the sustained narrowness observed in the
asymptotic cylindrical region of bipolar outflows from Young Stellar Objects
(YSO) indicates that these jets are magnetically collimated. The j cross B
force observed in z-pinch plasmas is a possible explanation for these
observations. However, z-pinch plasmas are subject to current driven
instabilities (CDI). The interest in using z-pinches for controlled nuclear
fusion has lead to an extensive theory of the stability of magnetically
confined plasmas. Analytical, numerical, and experimental evidence from this
field suggest that sheared flow in magnetized plasmas can reduce the growth
rates of the sausage and kink instabilities. Here we propose the hypothesis
that sheared helical flow can exert a similar stabilizing influence on CDI in
YSO jets.Comment: 13 pages, 2 figure
A Lorentz-Poincar\'e type interpretation of the Weak Equivalence Principle
The validity of the Weak Equivalence Principle relative to a local inertial
frame is detailed in a scalar-vector gravitation model with Lorentz-Poincar\'e
type interpretation. Given the previously established first Post-Newtonian
concordance of dynamics with General Relativity, the principle is to this order
compatible with GRT. The gravitationally modified Lorentz transformations, on
which the observations in physical coordinates depend, are shown to provide a
physical interpretation of \emph{parallel transport}. A development of
``geodesic'' deviation in terms of the present model is given as well.Comment: v1: 9 pages, 2 figures, v2: version to appear in International
Journal of Theoretical Physic
Bio-Energy Production from Anaerobic Digestion of Animal and Farm Wastes
Track II: Transportation and BiofuelsIncludes audio file (20 min.)US produces annually huge amount of animal and farm wastes (e.g. only cow manure in amount of about 1.8 billion tons). These wastes can be valuable source of renewable energy besides overcoming the environmental problems caused by them such as greenhouse gas effect of methane emission of 22 times worse than carbon dioxide, surface and ground water contamination, odor, dust, ammonia leaching, etc. In this project we systematically studied the process, kinetics, microorganisms interaction and population, and the effects of design and operating parameters on reactor design and scale up of cow manure digestion for bioenergy production and for wastes treatment by developing and implementing advanced imaging, visualization and computational techniques such as computational fluid dynamics (CFD), novel multiple radioactive particles tracking technique (MRPT), novel dual source computed tomography (DSCT), and microbiology imaging techniques. New design and conditions of anaerobic digesters that can reduce significantly the inactive volume and improve the digesters performance have been identified and recommended. In addition, for the first time, the energy produced has been related to the energy introduced in order to maximize the energy output while minimizing the energy input through the mixing power consumed. It is hoped that the findings will be applied in the field to promote bioenergy production and eliminate major environmental pollution problems
Characterization of the ATP4 ion pump in Toxoplasma gondii
The Plasmodium falciparum ATPase PfATP4 is the target of a diverse range of antimalarial compounds, including the clinical drug candidate cipargamin. PfATP4 was originally annotated as a Ca2+ transporter, but recent evidence suggests that it is a Na+ efflux pump, extruding Na+ in exchange for H+. Here we demonstrate that ATP4 proteins belong to a clade of P-type ATPases that are restricted to apicomplexans and their closest relatives. We employed a variety of genetic and physiological approaches to investigate the ATP4 protein of the apicomplexan Toxoplasma gondii, TgATP4. We show that TgATP4 is a plasma membrane protein. Knockdown of TgATP4 had no effect on resting pH or Ca2+ but rendered parasites unable to regulate their cytosolic Na+ concentration ([Na+]cyt). PfATP4 inhibitors caused an increase in [Na+]cyt and a cytosolic alkalinization in WT but not TgATP4 knockdown parasites. Parasites in which TgATP4 was knocked down or disrupted exhibited a growth defect, attributable to reduced viability of extracellular parasites. Parasites in which TgATP4 had been disrupted showed reduced virulence in mice. These results provide evidence for ATP4 proteins playing a key conserved role in Na+ regulation in apicomplexan parasites.This work was supported by National Health and Medical Research Council Grant 1042272 (to K. K.) and Australian Research Council Discovery Project Grant DP150102883 (to K. K. and G. G. v. D.), Linkage Project Grant LP150101226 (to K. K.), Discovery Early Career Researcher Award DE160101035 (to A. M. L.), QEII Fellowship DP110103144 (to G. G. v. D.), and Future Fellowship FT120100164 (to C. J. T.). C. J. T. is grateful for institutional support from the Victorian State Government Operational Infrastructure Support Program and the National Health and Medical Research Council Independent Research Institute Infrastructure Support Scheme
A Census of the Chamaeleon I Star-Forming Region
Optical spectroscopy has been obtained for 179 objects that have been
previously identified as possible members of the cluster, that lack either
accurate spectral types or clear evidence of membership, and that are optically
visible (I<18). I have used these spectroscopic data and all other available
constraints to evaluate the spectral classifications and membership status of a
total sample of 288 candidate members of Chamaeleon I that have appeared in
published studies of the cluster. The latest census of Chamaeleon I now
contains 158 members, 8 of which are later than M6 and thus are likely to be
brown dwarfs. I find that many of the objects identified as members of
Chamaeleon I in recent surveys are actually field stars. Meanwhile, 7 of 9
candidates discovered by Carpenter and coworkers are confirmed as members, one
of which is the coolest known member of Chamaeleon I at a spectral type of M8
(~0.03 M_sun). I have estimated extinctions, luminosities, and effective
temperatures for the members and used these data to construct an H-R diagram
for the cluster. Chamaeleon I has a median age of ~2 Myr according to
evolutionary models, and hence is similar in age to IC 348 and is slightly
older than Taurus (~1 Myr). The measurement of an IMF for Chamaeleon I from
this census is not possible because of the disparate methods with which the
known members were originally selected, and must await an unbiased,
magnitude-limited survey of the cluster.Comment: 59 pages, 22 figure
On Slow Light as a Black Hole Analogue
Although slow light (electromagnetically induced transparency) would seem an
ideal medium in which to institute a ``dumb hole'' (black hole analog), it
suffers from a number of problems. We show that the high phase velocity in the
slow light regime ensures that the system cannot be used as an analog
displaying Hawking radiation. Even though an appropriately designed slow-light
set-up may simulate classical features of black holes -- such as horizon, mode
mixing, Bogoliubov coefficients, etc. -- it does not reproduce the related
quantum effects. PACS: 04.70.Dy, 04.80.-y, 42.50.Gy, 04.60.-m.Comment: 14 pages RevTeX, 5 figure
Thermodynamic Gravity and the Schrodinger Equation
We adopt a 'thermodynamical' formulation of Mach's principle that the rest
mass of a particle in the Universe is a measure of its long-range collective
interactions with all other particles inside the horizon. We consider all
particles in the Universe as a 'gravitationally entangled' statistical ensemble
and apply the approach of classical statistical mechanics to it. It is shown
that both the Schrodinger equation and the Planck constant can be derived
within this Machian model of the universe. The appearance of probabilities,
complex wave functions, and quantization conditions is related to the
discreetness and finiteness of the Machian ensemble.Comment: Minor corrections, the version accepted by Int. J. Theor. Phy
Turning Points in the Evolution of Isolated Neutron Stars' Magnetic Fields
During the life of isolated neutron stars (NSs) their magnetic field passes
through a variety of evolutionary phases. Depending on its strength and
structure and on the physical state of the NS (e.g. cooling, rotation), the
field looks qualitatively and quantitatively different after each of these
phases. Three of them, the phase of MHD instabilities immediately after NS's
birth, the phase of fallback which may take place hours to months after NS's
birth, and the phase when strong temperature gradients may drive thermoelectric
instabilities, are concentrated in a period lasting from the end of the
proto--NS phase until 100, perhaps 1000 years, when the NS has become almost
isothermal. The further evolution of the magnetic field proceeds in general
inconspicuous since the star is in isolation. However, as soon as the product
of Larmor frequency and electron relaxation time, the so-called magnetization
parameter, locally and/or temporally considerably exceeds unity, phases, also
unstable ones, of dramatic changes of the field structure and magnitude can
appear. An overview is given about that field evolution phases, the outcome of
which makes a qualitative decision regarding the further evolution of the
magnetic field and its host NS.Comment: References updated, typos correcte
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