2,440 research outputs found
Receptor-type Guanylyl Cyclases Confer Thermosensory Responses in C. elegans.
Thermosensation is critical for optimal regulation of physiology and behavior. C. elegans acclimates to its cultivation temperature (Tc) and exhibits thermosensitive behaviors at temperatures relative to Tc. These behaviors are mediated primarily by the AFD sensory neurons, which are extraordinarily thermosensitive and respond to thermal fluctuations at temperatures above a Tc-determined threshold. Although cGMP signaling is necessary for thermotransduction, the thermosensors in AFD are unknown. We show that AFD-specific receptor guanylyl cyclases (rGCs) are instructive for thermosensation. In addition to being necessary for thermotransduction, ectopic expression of these rGCs confers highly temperature-dependent responses onto diverse cell types. We find that the temperature response threshold is determined by the rGC and cellular context, and that multiple domains contribute to their thermosensory properties. Identification of thermosensory rGCs in C. elegans provides insight into mechanisms of thermosensation and thermal acclimation and suggests that rGCs may represent a new family of molecular thermosensors.This work was funded in part by the NIH (R01 GM081639 and P01 GM103770 – P.S., T32007292 – V.M.H. and P01NS079419 - T.O.).This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.neuron.2016.03.00
Renormalisation of heavy-light light ray operators
We calculate the renormalisation of different light ray operators with one
light degree of freedom and a static heavy quark. Both - and
-kernels are considered. A comparison with the light-light case suggests
that the mixing with three-particle operators is solely governed by the light
degrees of freedom. Additionally we show that conformal symmetry is already
broken at the level of the one loop counterterms due to the additional
UV-renormalisation of a cusp in the two contributing Wilson-lines. This general
feature can be used to fix the -renormalisation kernels up to a
constant. Some examples for applications of our results are given.Comment: 23 pages, 5 figures; v2: changed some wording, added a few references
and one appendix concerning some subtleties related to gauge fixing and ghost
terms; v3: clarified calculation in section 3.2., added an explicit
calculation in section 5.2, corrected a few typos and one figure, added a few
comments, results unchanged, except for typesetting matches version to appear
in JHE
Massive rearrangements of cellular MicroRNA signatures are key drivers of hepatocyte dedifferentiation
Hepatocytes are dynamic cells that, upon injury, can alternate between nondividing differentiated and dedifferentiated proliferating states in vivo . However, in two‐dimensional cultures, primary human hepatocytes (PHHs) rapidly dedifferentiate, resulting in loss of hepatic functions that significantly limits their usefulness as an in vitro model of liver biology, liver diseases, as well as drug metabolism and toxicity. Thus, understanding the underlying mechanisms and stalling of the dedifferentiation process would be highly beneficial to establish more‐accurate and relevant long‐term in vitro hepatocyte models. Here, we present comprehensive analyses of whole proteome and transcriptome dynamics during the initiation of dedifferentiation during the first 24 hours of culture. We report that early major rearrangements of the noncoding transcriptome, hallmarked by increased expression of small nucleolar RNAs, long noncoding RNAs, microRNAs (miRNAs), and ribosomal genes, precede most changes in coding genes during dedifferentiation of PHHs, and we speculated that these modulations could drive the hepatic dedifferentiation process. To functionally test this hypothesis, we globally inhibited the miRNA machinery using two established chemically distinct compounds, acriflavine and poly‐l ‐lysine. These inhibition experiments resulted in a significantly impaired miRNA response and, most important, in a pronounced reduction in the down‐regulation of hepatic genes with importance for liver function. Thus, we provide strong evidence for the importance of noncoding RNAs, in particular, miRNAs, in hepatic dedifferentiation, which can aid the development of more‐efficient differentiation protocols for stem‐cell‐derived hepatocytes and broaden our understanding of the dynamic properties of hepatocytes with respect to liver regeneration. Conclusion: miRNAs are important drivers of hepatic dedifferentiation, and our results provide valuable information regarding the mechanisms behind liver regeneration and possibilities to inhibit dedifferentiation in vitro
Search for electromagnetic properties of the neutrinos at the LHC
Exclusive production of neutrinos via photon-photon fusion provides an
excellent opportunity to probe electromagnetic properties of the neutrinos at
the LHC. We explore the potential of processes pp-> p gamma gamma p -> p nu
anti-nu p and pp -> p gamma gamma p -> p nu anti-nu Z p to probe
neutrino-photon and neutrino-two photon couplings. We show that these reactions
provide more than seven orders of magnitude improvement in neutrino-two photon
couplings compared to LEP limits.Comment: 11 pages, 4 tables, New backgrounds have been adde
Binary and Millisecond Pulsars at the New Millennium
We review the properties and applications of binary and millisecond pulsars.
Our knowledge of these exciting objects has greatly increased in recent years,
mainly due to successful surveys which have brought the known pulsar population
to over 1300. There are now 56 binary and millisecond pulsars in the Galactic
disk and a further 47 in globular clusters. This review is concerned primarily
with the results and spin-offs from these surveys which are of particular
interest to the relativity community.Comment: 59 pages, 26 figures, 5 tables. Accepted for publication in Living
Reviews in Relativity (http://www.livingreviews.org
P-odd and CP-odd Four-Quark Contributions to Neutron EDM
In a class of beyond-standard-model theories, CP-odd observables, such as the
neutron electric dipole moment, receive significant contributions from
flavor-neutral P-odd and CP-odd four-quark operators. However, considerable
uncertainties exist in the hadronic matrix elements of these operators strongly
affecting the experimental constraints on CP-violating parameters in the
theories. Here we study their hadronic matrix elements in combined chiral
perturbation theory and nucleon models. We first classify the operators in
chiral representations and present the leading-order QCD evolutions. We then
match the four-quark operators to the corresponding ones in chiral hadronic
theory, finding symmetry relations among the matrix elements. Although this
makes lattice QCD calculations feasible, we choose to estimate the
non-perturbative matching coefficients in simple quark models. We finally
compare the results for the neutron electric dipole moment and P-odd and CP-odd
pion-nucleon couplings with the previous studies using naive factorization and
QCD sum rules. Our study shall provide valuable insights on the present
hadronic physics uncertainties in these observables.Comment: 40 pages, 7 figures. This is the final version. A discussion of the
uncertainty of the calculation is adde
The Hubble Constant
I review the current state of determinations of the Hubble constant, which
gives the length scale of the Universe by relating the expansion velocity of
objects to their distance. There are two broad categories of measurements. The
first uses individual astrophysical objects which have some property that
allows their intrinsic luminosity or size to be determined, or allows the
determination of their distance by geometric means. The second category
comprises the use of all-sky cosmic microwave background, or correlations
between large samples of galaxies, to determine information about the geometry
of the Universe and hence the Hubble constant, typically in a combination with
other cosmological parameters. Many, but not all, object-based measurements
give values of around 72-74km/s/Mpc , with typical errors of 2-3km/s/Mpc.
This is in mild discrepancy with CMB-based measurements, in particular those
from the Planck satellite, which give values of 67-68km/s/Mpc and typical
errors of 1-2km/s/Mpc. The size of the remaining systematics indicate that
accuracy rather than precision is the remaining problem in a good determination
of the Hubble constant. Whether a discrepancy exists, and whether new physics
is needed to resolve it, depends on details of the systematics of the
object-based methods, and also on the assumptions about other cosmological
parameters and which datasets are combined in the case of the all-sky methods.Comment: Extensively revised and updated since the 2007 version: accepted by
Living Reviews in Relativity as a major (2014) update of LRR 10, 4, 200
Common Selfcare Indications of Pain Medications in Children.
Pain has a multifaceted impact on individuals worldwide, affecting their physical functioning, emotional well-being, and quality of life. Children (age < 18 years) have a high prevalence of conditions associated with pain, such as toothache, headache, earache, sore throat, and respiratory tract infections, many of which may be accompanied by fever. Globally, the pharmacologic treatment of pain in pediatric patients is limited largely to nonopioid analgesics, and dosing must account for differences in age, weight, metabolism, and risk of adverse effects. This narrative review summarizes the findings of a literature search on the pediatric indications, dosing approaches, dosing guidelines, and pharmacokinetics of paracetamol and ibuprofen, which are common pain medications available globally for self-care use in children. The review also discusses the risks and benefits associated with these agents. The current roles of paracetamol and ibuprofen in the symptomatic management of coronavirus disease 2019 (COVID-19) infection and in the management of post-COVID-19 immunization symptoms in children are also discussed. Therefore, while a very large amount of data over several decades is available for paracetamol and ibuprofen, an urgent need exists for well-designed studies of these medications for the management of pain and fever in pediatric patients with COVID-19 to ensure optimal relief with minimal toxicity
Strongly magnetized pulsars: explosive events and evolution
Well before the radio discovery of pulsars offered the first observational
confirmation for their existence (Hewish et al., 1968), it had been suggested
that neutron stars might be endowed with very strong magnetic fields of
-G (Hoyle et al., 1964; Pacini, 1967). It is because of their
magnetic fields that these otherwise small ed inert, cooling dead stars emit
radio pulses and shine in various part of the electromagnetic spectrum. But the
presence of a strong magnetic field has more subtle and sometimes dramatic
consequences: In the last decades of observations indeed, evidence mounted that
it is likely the magnetic field that makes of an isolated neutron star what it
is among the different observational manifestations in which they come. The
contribution of the magnetic field to the energy budget of the neutron star can
be comparable or even exceed the available kinetic energy. The most magnetised
neutron stars in particular, the magnetars, exhibit an amazing assortment of
explosive events, underlining the importance of their magnetic field in their
lives. In this chapter we review the recent observational and theoretical
achievements, which not only confirmed the importance of the magnetic field in
the evolution of neutron stars, but also provide a promising unification scheme
for the different observational manifestations in which they appear. We focus
on the role of their magnetic field as an energy source behind their persistent
emission, but also its critical role in explosive events.Comment: Review commissioned for publication in the White Book of
"NewCompStar" European COST Action MP1304, 43 pages, 8 figure
Rotation Curves of Spiral Galaxies
Rotation curves of spiral galaxies are the major tool for determining the
distribution of mass in spiral galaxies. They provide fundamental information
for understanding the dynamics, evolution and formation of spiral galaxies. We
describe various methods to derive rotation curves, and review the results
obtained. We discuss the basic characteristics of observed rotation curves in
relation to various galaxy properties, such as Hubble type, structure,
activity, and environment.Comment: 40 pages, 6 gif figures; Ann. Rev. Astron. Astrophys. Vol. 39, p.137,
200
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