5,348 research outputs found
secCl is a cys-loop ion channel necessary for the chloride conductance that mediates hormone-induced fluid secretion in Drosophila
Organisms use circulating diuretic hormones to control water balance (osmolarity), thereby avoiding dehydration and managing excretion of waste products. The hormones act through G-protein-coupled receptors to activate second messenger systems that in turn control the permeability of secretory epithelia to ions like chloride. In insects, the chloride channel mediating the effects of diuretic hormones was unknown. Surprisingly, we find a pentameric, cys-loop chloride channel, a type of channel normally associated with neurotransmission, mediating hormone-induced transepithelial chloride conductance. This discovery is important because: 1) it describes an unexpected role for pentameric receptors in the membrane permeability of secretory epithelial cells, and 2) it suggests that neurotransmitter-gated ion channels may have evolved from channels involved in secretion
No floors: Effective field theory treatment of the neutrino background in direct dark matter detection experiments
Distinguishing a dark matter interaction from an astrophysical
neutrino-induced interaction will be major challenge for future direct dark
matter searches. In this paper, we consider this issue within non-relativistic
Effective Field Theory (EFT), which provides a well-motivated theoretical
framework for determining nuclear responses to dark matter scattering events.
We analyze the nuclear energy recoil spectra from the different dark
matter-nucleon EFT operators, and compare to the nuclear recoil energy spectra
that is predicted to be induced by astrophysical neutrino sources. We determine
that for 11 of the 14 possible operators, the dark matter-induced recoil
spectra can be cleanly distinguished from the corresponding neutrino-induced
recoil spectra with moderate size detector technologies that are now being
pursued, e.g., these operators would require 0.5 tonne years to be
distinguished from the neutrino background for low mass dark matter. Our
results imply that in most models detectors with good energy resolution will be
able to distinguish a dark matter signal from a neutrino signal, without the
need for much larger detectors that must rely on additional information from
timing or direction
The blind leading the blind: Mutual refinement of approximate theories
The mutual refinement theory, a method for refining world models in a reactive system, is described. The method detects failures, explains their causes, and repairs the approximate models which cause the failures. The approach focuses on using one approximate model to refine another
Dynamic Normalization for Compact Binary Coalescence Searches in Non-Stationary Noise
The output of gravitational-wave interferometers, such as LIGO and Virgo, can be highly non-stationary. Broadband detector noise can affect the detector sensitivity on the order of tens of seconds. Gravitational-wave transient searches, such as those for colliding black holes, estimate this noise in order to identify gravitational-wave events. During times of non-stationarity we see a higher rate of false events being reported. To accurately separate signal from noise, it is imperative to incorporate the changing detector state into gravitational-wave searches. We develop a new statistic which estimates the variation of the interferometric detector noise. We use this statistic to re-rank candidate events identified during LIGO-Virgo's second observing run by the PyCBC search pipeline. This results in a 7% improvement in the sensitivity volume for low mass binaries, particularly binary neutron stars mergers
Modified Pati-Salam Model from orbifolded AdS/CFT
We consider models built on orbifold
compactifications of the type superstring, where is the abelian
group . An attractive three family SUSY model is found for
that is a modified Pati--Salam Model which reduced to the Standard Model
after symmetry breaking.Comment: 8 pages, 1 figure, Phenomenology section revised to correct
renormalization group equations, typos correcte
The Scientific Reach of Multi-Ton Scale Dark Matter Direct Detection Experiments
The next generation of large scale WIMP direct detection experiments have the
potential to go beyond the discovery phase and reveal detailed information
about both the particle physics and astrophysics of dark matter. We report here
on early results arising from the development of a detailed numerical code
modeling the proposed DARWIN detector, involving both liquid argon and xenon
targets. We incorporate realistic detector physics, particle physics and
astrophysical uncertainties and demonstrate to what extent two targets with
similar sensitivities can remove various degeneracies and allow a determination
of dark matter cross sections and masses while also probing rough aspects of
the dark matter phase space distribution. We find that, even assuming dominance
of spin-independent scattering, multi-ton scale experiments still have
degeneracies that depend sensitively on the dark matter mass, and on the
possibility of isospin violation and inelasticity in interactions. We find that
these experiments are best able to discriminate dark matter properties for dark
matter masses less than around 200 GeV. In addition, and somewhat surprisingly,
the use of two targets gives only a small improvement (aside from the advantage
of different systematics associated with any claimed signal) in the ability to
pin down dark matter parameters when compared with one target of larger
exposure.Comment: 23 pages; updated to match PRD versio
The Migdal Effect and Photon Bremsstrahlung in effective field theories of dark matter direct detection and coherent elastic neutrino-nucleus scattering
Dark matter direct detection experiments have limited sensitivity to light
dark matter (below a few GeV), due to the challenges of lowering energy
thresholds for the detection of nuclear recoil to below
. While impressive progress has been made on this
front, light dark matter remains the least constrained region of dark-matter
parameter space. It has been shown that both ionization and excitation due to
the Migdal effect and coherently-emitted photon bremsstrahlung from the
recoiling atom can provide observable channels for light dark matter that would
otherwise have been missed owing to the resulting nuclear recoil falling below
the detector threshold. In this paper we extend previous work by calculating
the Migdal effect and photon bremmstrahlung rates for a general set of
interaction types, including those that are momentum-independent or -dependent,
spin-independent or -dependent, as well as examining the rates for a variety of
target materials, allowing us to place new experimental limits on some of these
interaction types. Additionally, we include a calculation of these effects
induced by the coherent scattering on nuclei of solar or atmospheric neutrinos.
We demonstrate that the Migdal effect dominates over the bremsstrahlung effect
for all targets considered for interactions induced by either dark matter or
neutrinos. This reduces photon bremsstrahlung to irrelevancy for future direct
detection experiments.Comment: 17 pages, 6 figure
Case 3 : “School, Interrupted”
Due to the fact that there is currently no national youth mental health strategy, each jurisdiction is faced with managing and preventing mental health issues in their communities. Through school-based mental health interventions public health professionals have the potential to impact a large portion of youth in their community in a setting with which youth are already familiar. Susan Miller, a health promoter with the Great Lakes Public Health Unit, has been tasked with making recommendations about what type of mental health intervention should be implemented in the local elementary and high schools. The main objective of this mental health intervention will be to enhance protective factors among youth as well as to decrease the risk factors that can lead to developing further mental health issues in adulthood
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