198 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 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
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
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
Drug Interactions between Dolutegravir and Artemether-Lumefantrine or Artesunate-Amodiaquine
ABSTRACTAcross sub-Saharan Africa, patients with HIV on antiretrovirals often get malaria and need cotreatment with artemisinin-containing therapies. We undertook two pharmacokinetic studies in healthy volunteers, using standard adult doses of artmether-lumefantrine (AL) or artesunate-amodiaquine (AS-AQ) given with 50mg once daily dolutegravir (DTG) to investigate the drug-drug interaction between artmether-lumefantrine or artesunate-amodiaquine and DTG. The DTG/artmether-lumefantrine interaction was evaluated in a two-way cross-over study and measured artemether (ARM), dihydroartemisinin (DHA), lumefantrine (LF), desbutyl-lumefantrine (DBL) over 264h. The DTG/artesunate-amodiaquine interaction was investigated using a parallel study design due to long half-life of the amodiaquine metabolite, desethylamodiaquine (DEAQ) and measured artesunate (ARS), amodiaquine (AQ), DEAQ over 624h. Non-compartmental analysis was performed, and geometric mean ratios and 90% confidence intervals generated for evaluation of both interactions. Dolutegravir did not significantly change the maximum concentration in plasma, time to maximum concentration and area under the concentration-time curve (AUC) for ARM, DHA, LF and DBL nor significantly alter AUC for ARS, DHA, AQ and DEAQ. Co-administration of dolutegravir with AL resulted in a 37% decrease in DTG trough concentrations. Co-administration of dolutegravir with AS-AQ resulted in a decrease of approximately 42% and 24% in DTG trough concentrations and AUC respectively. Study drugs were well-tolerated with no serious adverse events. Standard doses of artmether-lumefantrine and artesunate-amodiaquine should be used in patients receiving DTG. The significant decreases in DTG trough concentrations with artemether-lumefantrine and artesunate-amodiaquine and DTG exposure with artesunate-amodiaquine are unlikely to be of clinical significance as DTG trough concentrations were above DTG target concentrations of 64ng/mL.</jats:p
Protein Expression of the Microglial Marker Tmem119 Decreases in Association With Morphological Changes and Location in a Mouse Model of Traumatic Brain Injury
The activation of microglia and the infiltration of macrophages are hallmarks of neuroinflammation after acute brain injuries, including traumatic brain injury (TBI). The two myeloid populations share many features in the post-injury inflammatory response, thus, being antigenically indistinguishable. Recently Tmem119, a type I transmembrane protein specifically expressed by microglia under physiological conditions, was proposed as a tool to differentiate resident microglia from blood-borne macrophages, not expressing it. However, the validity of Tmem119 as a specific marker of resident microglia in the context of acute brain injury, where microglia are activated and macrophages are recruited, needs validation. Our purpose was to investigate Tmem119 expression and distribution in relation to the morphology of brain myeloid cells present in the injured area after TBI. Mice underwent sham surgery or TBI by controlled cortical impact (CCI). Brains from sham-operated, or TBI mice, were analyzed by in situ hybridization to identify the cells expressing Tmem119, and by Western blot and quantitative immunofluorescence to measure Tmem119 protein levels in the entire brain regions and single cells. The morphology of Iba1+ myeloid cells was analyzed at different times (4 and 7 days after TBI) and several distances from the contused edge in order to associate Tmem119 expression with morphological evolution of active microglia. In situ hybridization indicated an increased Tmem119 RNA along with increased microglial complement C1q activation in the contused area and surrounding regions. On the contrary, the biochemical evaluation showed a drop in Tmem119 protein levels in the same areas. The Tmem119 immunoreactivity decreased in Iba1+ myeloid cells found in the contused cortex at both time points, with the cells showing the hypertrophic ameboid morphology having no Tmem119 expression. The Tmem119 was present on ramifications of resident microglia and its presence was decreased as a consequence of microglial activation in cortical areas close to contusion. Based on the data, we conclude that the decrease of Tmem119 in reactive microglia may depend on the process of microglial activation, which involves the retracting of their branchings to acquire an ameboid shape. The Tmem119 immunoreactivity decreases in reactive microglia to similar levels than the blood-borne macrophages, thus, failing to discriminate the two myeloid populations after TBI.This work was supported by the ERA-NET NEURON, JTC 2016: LEAP, NEURON9-FP-044 from the following national funding institutions: Italian Ministry of Health (Ministero della Salute), Italy; Ministerio de EconomĂa, Industria y Competitividad (PCIN-2017-035) Spain; 01EW1703, Bundesministerium fĂĽr Bildung und Forschung (BMBF), Germany.Peer reviewe
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