11 research outputs found
Velocity-dependent inverse cubic force and solar system gravity tests
Higher mass dimension terms in an effective field theory framework for tests
of spacetime symmetries are studied. Using a post-Newtonian expansion method,
we derive the spacetime metric and the equations of motion for a binary system.
This reveals an inverse cubic force correction to General Relativity that
depends on the velocity of the bodies in the system. The results are studied in
the context of laboratory and space-based tests including the effects on
solar-system ephemeris, laser ranging observations, and gravimeter tests. This
work reveals the coefficient combinations for mass dimension 5 operators
controlling CPT violation for gravity that can be measured using analysis from
these tests. Other tests including light propagation can be used to probe these
coefficients. Sensitivity estimates are provided and the results are contrasted
with the minimal mass dimension 4 terms in the gravity sector.Comment: 10 pages, matches published versio
The serotonergic psychedelic N,N-dipropyltryptamine alters information-processing dynamics in cortical neural circuits
Most of the recent work in psychedelic neuroscience has been done using
non-invasive neuroimaging, with data recorded from the brains of adult
volunteers under the influence of a variety of drugs. While this data provides
holistic insights into the effects of psychedelics on whole-brain dynamics, the
effects of psychedelics on the meso-scale dynamics of cortical circuits remains
much less explored. Here, we report the effects of the serotonergic psychedelic
N,N-diproptyltryptamine (DPT) on information-processing dynamics in a sample of
in vitro organotypic cultures made from rat cortical tissue. Three hours of
spontaneous activity were recorded: an hour of pre-drug control, and hour of
exposure to 10M DPT solution, and a final hour of washout, once again
under control conditions. We found that DPT reversibly alters information
dynamics in multiple ways: first, the DPT condition was associated with higher
entropy of spontaneous firing activity and reduced the amount of time
information was stored in individual neurons. Second, DPT also reduced the
reversibility of neural activity, increasing the entropy produced and
suggesting a drive away from equilibrium. Third, DPT altered the structure of
neuronal circuits, decreasing the overall information flow coming into each
neuron, but increasing the number of weak connections, creating a dynamic that
combines elements of integration and disintegration. Finally, DPT decreased the
higher-order statistical synergy present in sets of three neurons.
Collectively, these results paint a complex picture of how psychedelics
regulate information processing in meso-scale cortical tissue. Implications for
existing hypotheses of psychedelic action, such as the Entropic Brain
Hypothesis, are discussed.Comment: 19 pages, 2 figure
Hepatic Transcriptome Analysis of Hepatitis C Virus Infection in Chimpanzees Defines Unique Gene Expression Patterns Associated with Viral Clearance
Hepatitis C virus infection leads to a high rate of chronicity. Mechanisms of viral clearance and persistence are still poorly understood. In this study, hepatic gene expression analysis was performed to identify any molecular signature associated with the outcome of hepatitis C virus (HCV) infection in chimpanzees. Acutely HCV-infected chimpanzees with self-limited infection or progression to chronicity were studied. Interferon stimulated genes were induced irrespective of the outcome of infection. Early induction of a set of genes associated with cell proliferation and immune activation was associated with subsequent viral clearance. Specifically, two of the genes: interleukin binding factor 3 (ILF3) and cytotoxic granule-associated RNA binding protein (TIA1), associated with robust T-cell response, were highly induced early in chimpanzees with self-limited infection. Up-regulation of genes associated with CD8+ T cell response was evident only during the clearance phase of the acute self-limited infection. The induction of these genes may represent an initial response of cellular injury and proliferation that successfully translates to a “danger signal” leading to induction of adaptive immunity to control viral infection. This primary difference in hepatic gene expression between self-limited and chronic infections supports the concept that successful activation of HCV-specific T-cell response is critical in clearance of acute HCV infection
Analysis of Duck Hepatitis B Virus Reverse Transcription Indicates a Common Mechanism for the Two Template Switches during Plus-Strand DNA Synthesis
The synthesis of the hepadnavirus relaxed circular DNA genome requires two template switches, primer translocation and circularization, during plus-strand DNA synthesis. Repeated sequences serve as donor and acceptor templates for these template switches, with direct repeat 1 (DR1) and DR2 for primer translocation and 5′r and 3′r for circularization. These donor and acceptor sequences are at, or near, the ends of the minus-strand DNA. Analysis of plus-strand DNA synthesis of duck hepatitis B virus (DHBV) has indicated that there are at least three other cis-acting sequences that make contributions during the synthesis of relaxed circular DNA. These sequences, 5E, M, and 3E, are located near the 5′ end, the middle, and the 3′ end of minus-strand DNA, respectively. The mechanism by which these sequences contribute to the synthesis of plus-strand DNA was unclear. Our aim was to better understand the mechanism by which 5E and M act. We localized the DHBV 5E element to a short sequence of approximately 30 nucleotides that is 100 nucleotides 3′ of DR2 on minus-strand DNA. We found that the new 5E mutants were partially defective for primer translocation/utilization at DR2. They were also invariably defective for circularization. In addition, examination of several new DHBV M variants indicated that they too were defective for primer translocation/utilization and circularization. Thus, this analysis indicated that 5E and M play roles in both primer translocation/utilization and circularization. In conjunction with earlier findings that 3E functions in both template switches, our findings indicate that the processes of primer translocation and circularization share a common underlying mechanism
Genes induced during the clearance phase of self-limited infection.
a<p>Expression levels of genes induced above the confidence interval at week 13 but below the confidence interval at weeks 4, 6 & 40 of X0190.</p><p>The bold and italicized values represent data above the 99% confidence interval as described in the text.</p
Genes induced during the early phase of self-limited infection as defined by average expression values.
a<p>Average expression values of biopsies taken during the 1<sup>st</sup> 8 weeks of infection.</p><p>Bold-face genes are also in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0003442#pone-0003442-t001" target="_blank">Table 1</a>.</p
Genes induced during the early phase of self-limited and persistent infections.
a<p>Expression levels of genes induced above the confidence interval at weeks 4 & 6 but below the confidence interval at weeks 13 & 40 in X0190.</p><p>The bold and italicized values represent data above the 99% confidence interval as described in the text.</p