8,914 research outputs found
The conceptus induces a switch in protein expression and activities of superoxide dismutase 1 and 2 in the sheep endometrium during early pregnancy
Acknowledgements We thank Philippe Bolifraud (INRA, France), Krawiec Angele, Sandra Grange, Laurence Puillet-Anselme (CHU Grenoble, France) and Margaret Fraser (Aberdeen, UK) for their expert technical assistance. The authors also thank the staff of the sheep sheds of Jouy-en-Josas (INRA, France). The authors would also like to thank the anonymous reviewers for their close examination of this article and their useful comments. Funding This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.Peer reviewedPostprin
The Equilibrium Distribution of Gas Molecules Adsorbed on an Active Surface
We evaluate the exact equilibrium distribution of gas molecules adsorbed on
an active surface with an infinite number of attachment sites. Our result is a
Poisson distribution having mean , with the
mean gas density, the sticking probability, the evaporation
probability in a time interval , and Smoluchowski's exit probability
in time interval for the surface in question. We then solve for the case
of a finite number of attachment sites using the mean field approximation,
recovering in this case the Langmuir isotherm.Comment: 14 pages done in late
The Solubility and Heat of Solution of Succinic Acid in Water and the Paraffin Alcohols
The following is the report of an investigation undertaken for the purpose of collecting further information concerning the influence of solvent upon certain specific properties of solutions. The solvents chosen, including water, represent the lower homologues of the paraffin alcohol series
Strong coupling in the Kondo problem in the low-temperature region
The magnetic field dependence of the average spin of a localized electron
coupled to conduction electrons with an antiferromagnetic exchange interaction
is found for the ground state. In the magnetic field range
( is the Kondo temperature) there is an inflection point, and in the
strong magnetic field range , the correction to the average spin
is proportional to . In zero magnetic field, the interaction
with conduction electrons also leads to the splitting of doubly degenerate spin
impurity states
Phenotypic variation and differentiated gene expression of Australian plants in response to declining rainfall
Declining rainfall is projected to have negative impacts on the demographic performance of plant species. Little is known about the adaptive capacity of species to respond to drying climates, and whether adaptation can keep pace with climate change. In fire-prone ecosystems, episodic recruitment of perennial plant species in the first year postfire imposes a specific selection environment, offering a unique opportunity to quantify the scope for adaptive response to climate change. We examined the growth of seedlings of four fire-killed species under control and drought conditions for seeds from populations established in years following fire receiving average-to-above-average winter rainfall, or well-below-average winter rainfall. We show that offspring of plants that had established under drought had more efficient water uptake, and/or stored more water per unit biomass, or developed denser leaves, and all maintained higher survival in simulated drought than did offspring of plants established in average annual rainfall years. Adaptive phenotypic responses were not consistent across all traits and species, while plants that had established under severe drought or established in years with average-to-above-average rainfall had an overall different physiological response when growing either with or without water constraints. Seedlings descended from plants established under severe drought also had elevated gene expression in key pathways relating to stress response. Our results demonstrate the capacity for rapid adaptation to climate change through phenotypic variation and regulation of gene expression. However, effective and rapid adaptation to climate change may vary among species depending on their capacity to maintain robust populations under multiple stresses
Ariel 6 measurements of ultra-heavy cosmic ray fluxes in the region 34 or = Z or = 48
The Ariel VI satellite was launched by NASA on a Scout rocket on 3rd June 1979 from Wallops Island, Virginia, USA, into a near circular 625 km orbit inclined at 55 deg. It carried a spherical cosmic ray detector designed by a group from Bristol University. A spherical aluminum vessel of diameter 75 cm contains a gas scintillation mixture and a thin spherical shell of Pilot 425 plastic, and forms a single optical cavity viewed by 16 photomultipliers. Particle tracks through the detector may be characterized by their impact parameter p and by whether or not they pass through the cup of plastic scintillator placed between the sphere and the spacecraft body (referred to below as the Anti-Coincidence Detector or ACD). Individual particle charges are determined by separately measuring the gas scintillation and the Cerenkov emission from the plastic shell. This is possible because of the quite different distribution in time of these emissions
Sustainability of water resources management in the Indus Basin under changing climatic and socio economic conditions
Pakistan is highly dependent on water resources originating in the mountain sources of the upper Indus for irrigated agriculture which is the mainstay of its economy. Hence any change in available resources through climate change or socio-economic factors could have a serious impact on food security and the environment. In terms of both ratio of withdrawals to runoff and per-capita water availability, Pakistan's water resources are already highly stressed and will become increasingly so with projected population changes. Potential changes to supply through declining reservoir storage, the impact of waterlogging and salinity or over-abstraction of groundwater, or reallocations for environmental remediation of the Indus Delta or to meet domestic demands, will reduce water availability for irrigation. <br><br> The impact of climate change on resources in the Upper Indus is considered in terms of three hydrological regimes – a nival regime dependent on melting of winter snow, a glacial regime, and a rainfall regime dependent on concurrent rainfall. On the basis of historic trends in climate, most notably the decline in summer temperatures, there is no strong evidence in favour of marked reductions in water resources from any of the three regimes. Evidence for changes in trans-Himalayan glacier mass balance is mixed. Sustainability of water resources appears more threatened by socio-economic changes than by climatic trends. Nevertheless, analysis and the understanding of the linkage of climate, glaciology and runoff is still far from complete; recent past climate experience may not provide a reliable guide to the future
Surface code quantum computing by lattice surgery
In recent years, surface codes have become a leading method for quantum error
correction in theoretical large scale computational and communications
architecture designs. Their comparatively high fault-tolerant thresholds and
their natural 2-dimensional nearest neighbour (2DNN) structure make them an
obvious choice for large scale designs in experimentally realistic systems.
While fundamentally based on the toric code of Kitaev, there are many variants,
two of which are the planar- and defect- based codes. Planar codes require
fewer qubits to implement (for the same strength of error correction), but are
restricted to encoding a single qubit of information. Interactions between
encoded qubits are achieved via transversal operations, thus destroying the
inherent 2DNN nature of the code. In this paper we introduce a new technique
enabling the coupling of two planar codes without transversal operations,
maintaining the 2DNN of the encoded computer. Our lattice surgery technique
comprises splitting and merging planar code surfaces, and enables us to perform
universal quantum computation (including magic state injection) while removing
the need for braided logic in a strictly 2DNN design, and hence reduces the
overall qubit resources for logic operations. Those resources are further
reduced by the use of a rotated lattice for the planar encoding. We show how
lattice surgery allows us to distribute encoded GHZ states in a more direct
(and overhead friendly) manner, and how a demonstration of an encoded CNOT
between two distance 3 logical states is possible with 53 physical qubits, half
of that required in any other known construction in 2D.Comment: Published version. 29 pages, 18 figure
Exactly solvable extended Hubbard model
In this work, we introduce long range version of the extended Hubbard model.
The system is defined on a non-uniform lattice. We show that the system is
integrable. The ground state, the ground state energies, the energy spectrum
are also found for the system. Another long range version of the extended
Hubbard model is also introduced on a uniform lattice, and this system is
proven to be integrable.Comment: 10 pages, Latex. Typoes are fixed in this revised versio
Decoherence and dephasing errors caused by D.C. Stark effect in rapid ion transport
We investigate the error due to D.C. Stark effect for quantum information
processing for trapped ion quantum computers using the scalable architecture
proposed in J. Res. Natl. Inst. Stan. 103, 259 (1998) and Nature 417, 709
(2002). As the operation speed increases, dephasing and decoherence due to the
D.C. Stark effect becomes prominent as a large electric field is applied for
transporting ions rapidly. We estimate the relative significance of the
decoherence and dephasing effects and find that the latter is dominant. We find
that the minimum possible of dephasing is quadratic in the time of flight, and
an inverse cubic in the operational time scale. From these relations, we obtain
the operational speed-range at which the shifts caused by D.C. Stark effect, no
matter follow which trajectory the ion is transported, are no longer
negligible. Without phase correction, the maximum speed a qubit can be
transferred across a 100 micron-long trap, without excessive error, in about 10
ns for Calcium ion and 50 ps for Beryllium ion. In practice, the accumulated
error is difficult to be tracked and calculated, our work gives an estimation
to the range of speed limit imposed by D.C. Stark effect.Comment: 7 pages, 1 figure. v2: Title is changed in this version to make our
argument more focused. Introduction is rewritten. A new section IV is added
to make our point more prominent. v3: Title is changed to make our argument
more specific. Abstract, introduction, and summary are revise
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