3,863 research outputs found
Cloning and functional characterisation of the duplicated RDL subunits from the pea aphid, Acyrthosiphon pisum
The insect GABA receptor, RDL (resistance to dieldrin), is a cys-loop ligand-gated ion channel (cysLGIC) that plays central roles in neuronal signaling and is the target of several classes of insecticides. Many insects studied to date possess one Rdl gene, however, there is evidence of two Rdls in aphids. To further characterize this insecticide target from pests that cause millions of dollars’ worth of crop damage each year, we identified the complete cysLGIC gene superfamily of the pea aphid, Acyrthosiphon pisum, using BLAST analysis. This confirmed the presence of two Rdl-like genes (RDL1 and RDL2) that likely arose from a recent gene duplication. When expressed individually in Xenopus laevis oocytes, both subunits formed functional ion channels gated by GABA. Alternative splicing of RDL1 influenced the potency of GABA and the potency of fipronil was different on the RDL1bd splice variant and RDL2. Imidacloprid and clothianidin showed no antagonistic activity on RDL1 whilst 100 M thiacloprid reduced the GABA responses of RDL1 and RDL2 to 55% and 62%, respectively. It is concluded that gene duplication of Rdl may have conferred increased tolerance to natural insecticides and played a role in the evolution of insect cysLGICs
Chimpanzee Rights: The Philosophers' Brief
In December 2013, the Nonhuman Rights Project (NhRP) filed a petition for a common law writ of habeas corpus in the New York State Supreme Court on behalf of Tommy, a chimpanzee living alone in a cage in a shed in rural New York (Barlow, 2017). Under animal welfare laws, Tommy’s owners, the Laverys, were doing nothing illegal by keeping him in those conditions. Nonetheless, the NhRP argued that given the cognitive, social, and emotional capacities of chimpanzees, Tommy’s confinement constituted a profound wrong that demanded remedy by the courts. Soon thereafter, the NhRP filed habeas corpus petitions on behalf of Kiko, another chimpanzee housed alone in Niagara Falls, and Hercules and Leo, two chimpanzees held in
research facilities at Stony Brook University. Thus began the legal struggle to move these chimpanzees from captivity to a sanctuary, an effort that has led the NhRP to argue in multiple courts before multiple judges. The central point of contention has been whether Tommy, Kiko, Hercules, and Leo have legal rights. To date, no judge has been willing to issue a writ of habeas corpus on their behalf. Such a ruling would mean that these chimpanzees have rights that confinement might violate. Instead, the judges have argued that chimpanzees cannot be bearers of legal rights because they are not, and cannot be persons. In this book we argue that chimpanzees are persons because they are autonomous
Variational data assimilation for the initial-value dynamo problem
The secular variation of the geomagnetic field as observed at the Earth's surface results from the complex magnetohydrodynamics taking place in the fluid core of the Earth. One way to analyze this system is to use the data in concert with an underlying dynamical model of the system through the technique of variational data assimilation, in much the same way as is employed in meteorology and oceanography. The aim is to discover an optimal initial condition that leads to a trajectory of the system in agreement with observations. Taking the Earth's core to be an electrically conducting fluid sphere in which convection takes place, we develop the continuous adjoint forms of the magnetohydrodynamic equations that govern the dynamical system together with the corresponding numerical algorithms appropriate for a fully spectral method. These adjoint equations enable a computationally fast iterative improvement of the initial condition that determines the system evolution. The initial condition depends on the three dimensional form of quantities such as the magnetic field in the entire sphere. For the magnetic field, conservation of the divergence-free condition for the adjoint magnetic field requires the introduction of an adjoint pressure term satisfying a zero boundary condition. We thus find that solving the forward and adjoint dynamo system requires different numerical algorithms. In this paper, an efficient algorithm for numerically solving this problem is developed and tested for two illustrative problems in a whole sphere: one is a kinematic problem with prescribed velocity field, and the second is associated with the Hall-effect dynamo, exhibiting considerable nonlinearity. The algorithm exhibits reliable numerical accuracy and stability. Using both the analytical and the numerical techniques of this paper, the adjoint dynamo system can be solved directly with the same order of computational complexity as that required to solve the forward problem. These numerical techniques form a foundation for ultimate application to observations of the geomagnetic field over the time scale of centuries
Lower bounds on the complexity of simulating quantum gates
We give a simple proof of a formula for the minimal time required to simulate
a two-qubit unitary operation using a fixed two-qubit Hamiltonian together with
fast local unitaries. We also note that a related lower bound holds for
arbitrary n-qubit gates.Comment: 6 page
Benefits of Exercise in Rheumatoid Arthritis
This paper aims to highlight the importance of exercise in patients with rheumatoid arthritis (RA) and to demonstrate the multitude of beneficial effects that properly designed exercise training has in this population. RA is a chronic, systemic, autoimmune disease characterised by decrements to joint health including joint pain and inflammation, fatigue, increased incidence and progression of cardiovascular disease, and accelerated loss of muscle mass, that is, “rheumatoid cachexia”. These factors contribute to functional limitation, disability, comorbidities, and reduced quality of life. Exercise training for RA patients has been shown to be efficacious in reversing cachexia and substantially improving function without exacerbating disease activity and is likely to reduce cardiovascular risk. Thus, all RA patients should be encouraged to include aerobic and resistance exercise training as part of routine care. Understanding the perceptions of RA patients and health professionals to exercise is key to patients initiating and adhering to effective exercise training
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The Incubation Period of Coronavirus Disease 2019 (COVID-19) From Publicly Reported Confirmed Cases: Estimation and Application
Background:
A novel human coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was identified in China in December 2019. There is limited support for many of its key epidemiologic features, including the incubation period for clinical disease (coronavirus disease 2019 [COVID-19]), which has important implications for surveillance and control activities. Objective:
To estimate the length of the incubation period of COVID-19 and describe its public health implications. Design:
Pooled analysis of confirmed COVID-19 cases reported between 4 January 2020 and 24 February 2020. Setting:
News reports and press releases from 50 provinces, regions, and countries outside Wuhan, Hubei province, China. Participants:
Persons with confirmed SARS-CoV-2 infection outside Hubei province, China. Measurements:
Patient demographic characteristics and dates and times of possible exposure, symptom onset, fever onset, and hospitalization. Results:
There were 181 confirmed cases with identifiable exposure and symptom onset windows to estimate the incubation period of COVID-19. The median incubation period was estimated to be 5.1 days (95% CI, 4.5 to 5.8 days), and 97.5% of those who develop symptoms will do so within 11.5 days (CI, 8.2 to 15.6 days) of infection. These estimates imply that, under conservative assumptions, 101 out of every 10 000 cases (99th percentile, 482) will develop symptoms after 14 days of active monitoring or quarantine. Limitation:
Publicly reported cases may overrepresent severe cases, the incubation period for which may differ from that of mild cases. Conclusion:
This work provides additional evidence for a median incubation period for COVID-19 of approximately 5 days, similar to SARS. Our results support current proposals for the length of quarantine or active monitoring of persons potentially exposed to SARS-CoV-2, although longer monitoring periods might be justified in extreme cases
Propagation of cosmic-ray nucleons in the Galaxy
We describe a method for the numerical computation of the propagation of
primary and secondary nucleons, primary electrons, and secondary positrons and
electrons. Fragmentation and energy losses are computed using realistic
distributions for the interstellar gas and radiation fields, and diffusive
reacceleration is also incorporated. The models are adjusted to agree with the
observed cosmic-ray B/C and 10Be/9Be ratios. Models with diffusion and
convection do not account well for the observed energy dependence of B/C, while
models with reacceleration reproduce this easily. The height of the halo
propagation region is determined, using recent 10Be/9Be measurements, as >4 kpc
for diffusion/convection models and 4-12 kpc for reacceleration models. For
convection models we set an upper limit on the velocity gradient of dV/dz < 7
km/s/kpc. The radial distribution of cosmic-ray sources required is broader
than current estimates of the SNR distribution for all halo sizes. Full details
of the numerical method used to solve the cosmic-ray propagation equation are
given.Comment: 15 pages including 23 ps-figures and 3 tables, latex2e, uses
emulateapj.sty (ver. of 11 May 1998, enclosed), apjfonts.sty, timesfonts.sty.
To be published in ApJ 1998, v.509 (December 10 issue). More details can be
found at http://www.gamma.mpe-garching.mpg.de/~aws/aws.html Some references
are correcte
Simulating Electron Transport and Synchrotron Emission in Radio Galaxies: Shock Acceleration and Synchrotron Aging in Axis-Symmetric Flows
We introduce a simple and economical but effective method for including
relativistic electron transport in multi-dimensional simulations of radio
galaxies. The method is designed to follow explicitly diffusive acceleration at
shocks, and, in smooth flows 2nd order Fermi acceleration plus adiabatic and
synchrotron cooling. We are able to follow both the spatial and energy
distributions of the electrons, so that direct synchrotron emission properties
can be modeled in time-dependent flows for the first time.
Here we present first results in the form of some axis-symmetric MHD
simulations of Mach 20 light jet flows. These show clearly the importance of
nonsteady terminal shocks that develop in such flows even when the jet inflow
is steady. As a result of this and other consequences of the fundamentally
driven character of jets, we find complex patterns of emissivities and
synchrotron spectra, including steep spectral gradients in hot spots, islands
of distinct spectra electrons within the lobes and spectral gradients coming
from the dynamical histories of a given flow element rather than from
synchrotron aging of the embedded electrons. In addition, spectral aging in the
lobes tends to proceed more slowly than one would estimate from regions of high
emissivity.Comment: 30 pages of Latex generated text plus 7 figures in gif format.
Accepted for publication in the Astrophysical Journal. High resolution
postscript figures available through anonymous ftp at
ftp://ftp.msi.umn.edu/pub/users/twj/RGje
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