3,163 research outputs found
Search for He-eta bound states with the WASA-at-COSY facility
The existence of eta-mesic nuclei in which the eta meson is bound in a
nucleus by means of the strong interaction was postulated already in 1986,
albeit not yet confirmed it by experiment. The discovery of this new kind of an
exotic nuclear matter would be very important as it might allow for a better
understanding of the eta meson structure and its interaction with nucleons. The
search for eta-mesic helium 4He-eta is carried out with high statistics and
high acceptance with the WASA detector, installed at the cooler synchrotron
COSY of the Research Center Juelich. The search is conducted via the
measurement of the excitation function for selected decay channels of the
4He-eta system. In the experiment, performed in November 2010, two reactions
dd->(4He-eta)bs ->3He p pi- and dd->(4He-eta)bs ->3He p pi0 were measured with
a beam momentum ramped from 2.127GeV/c to 2.422GeV/c. The report includes the
description of the experimental method and status of the measurement.Comment: Presented at the Erice School on Nuclear Physics 2011. 5 pages, 3
figure
Growing Green Energy: A Review of Extension\u27s Role in the Development of Advanced Biofuels
The development of advanced biofuels is expanding the possibilities for purpose-grown energy crops. Growers, producers, and other stakeholders will need a reliable source of information to assist with decision-making regarding renewable fuel supply chains. This review examines Extension\u27s role in the innovation of advanced biofuels by documenting and summarizing Extension work in existing biomass-derived energy programs. This review highlights strategies used by Extension programs that help make renewable energy innovations successful
Absolute conservation law for black holes
In all 2d theories of gravity a conservation law connects the (space-time
dependent) mass aspect function at all times and all radii with an integral of
the matter fields. It depends on an arbitrary constant which may be interpreted
as determining the initial value together with the initial values for the
matter field. We discuss this for spherically reduced Einstein-gravity in a
diagonal metric and in a Bondi-Sachs metric using the first order formulation
of spherically reduced gravity, which allows easy and direct fixations of any
type of gauge. The relation of our conserved quantity to the ADM and Bondi mass
is investigated. Further possible applications (ideal fluid, black holes in
higher dimensions or AdS spacetimes etc.) are straightforward generalizations.Comment: LaTex, 17 pages, final version, to appear in Phys. Rev.
Asymptotic symmetry and conservation laws in 2d Poincar\'e gauge theory of gravity
The structure of the asymptotic symmetry in the Poincar\'e gauge theory of
gravity in 2d is clarified by using the Hamiltonian formalism. The improved
form of the generator of the asymptotic symmetry is found for very general
asymptotic behaviour of phase space variables, and the related conserved
quantities are explicitly constructed.Comment: 22 pages, Plain Te
The Complete Solution of 2D Superfield Supergravity from graded Poisson-Sigma Models and the Super Pointparticle
Recently an alternative description of 2d supergravities in terms of graded
Poisson-Sigma models (gPSM) has been given. As pointed out previously by the
present authors a certain subset of gPSMs can be interpreted as "genuine"
supergravity, fulfilling the well-known limits of supergravity, albeit deformed
by the dilaton field. In our present paper we show that precisely that class of
gPSMs corresponds one-to-one to the known dilaton supergravity superfield
theories presented a long time ago by Park and Strominger. Therefore, the
unique advantages of the gPSM approach can be exploited for the latter: We are
able to provide the first complete classical solution for any such theory. On
the other hand, the straightforward superfield formulation of the point
particle in a supergravity background can be translated back into the gPSM
frame, where "supergeodesics" can be discussed in terms of a minimal set of
supergravity field degrees of freedom. Further possible applications like the
(almost) trivial quantization are mentioned.Comment: 48 pages, 1 figure. v3: after final version, typos correcte
Serum and acute phase protein changes in laying hens, infested with poultry red mite
The poultry red mite (PRM) is one of the most economically important ectoparasites of laying hens globally. This mite can have significant deleterious effects on its fowl host including distress, anemia, reduced egg production, and reduced egg quality. This study was conducted to evaluate the influence of PRM on the serum protein profile in laying hens and its effect on the acute phase proteins (APPs) to assess their potential as biomarkers for mite infestation.
Three APPs: alpha-1 acid glycoprotein (AGP), serum amyloid-A (SAA), and ceruloplasmin (CP) were measured in serum samples collected from laying hens at 12 and 17 wk of age, and then for up to 4 mo after a challenge with PRM (starting at 18.5 wk of age). The serum protein profile (SDS-PAGE/nanoflow HPLC electrospray tandem mass spectrometry) and concentration of individual serum proteins (SDS-PAGE-band densitometry) were also compared.
Post challenge there was a positive correlation (r = 0.489; P < 0.004) between the levels of SAA and the PRM numbers. The levels of SAA steadily increased after the PRM challenge and were significantly different than the pre-challenge levels at 28, 32, and 36 wk of age (P < 0.01). The PRM numbers also peaked around 31-33 wk of age. The results for AGP and CP in comparison were inconsistent. Proteomics revealed the presence of 2 high molecular weight proteins in the serum between 12 and 17 wk of age. These were identified as Apolipoprotein-B and Vitellogenin-2, and their increase was commensurate with the onset of lay. No other major differences were detected in the protein profiles of blood sera collected pre and post challenge. We conclude that SAA could be used as a useful biomarker to monitor PRM infestation in commercial poultry flocks and that PRM infestation does not disrupt the production of the major proteins in the serum that are associated with egg formation
Universal conservation law and modified Noether symmetry in 2d models of gravity with matter
It is well-known that all 2d models of gravity---including theories with
nonvanishing torsion and dilaton theories---can be solved exactly, if matter
interactions are absent. An absolutely (in space and time) conserved quantity
determines the global classification of all (classical) solutions. For the
special case of spherically reduced Einstein gravity it coincides with the mass
in the Schwarzschild solution. The corresponding Noether symmetry has been
derived previously by P. Widerin and one of the authors (W.K.) for a specific
2d model with nonvanishing torsion. In the present paper this is generalized to
all covariant 2d theories, including interactions with matter. The related
Noether-like symmetry differs from the usual one. The parameters for the
symmetry transformation of the geometric part and those of the matterfields are
distinct. The total conservation law (a zero-form current) results from a two
stage argument which also involves a consistency condition expressed by the
conservation of a one-form matter ``current''. The black hole is treated as a
special case.Comment: 3
Modeling photoelectron transport in the Martian ionosphere at Olympus Mons and Syrtis Major: MGS observations
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95423/1/jgra20373.pd
S-matrix for s-wave gravitational scattering
In the s-wave approximation the 4D Einstein gravity with scalar fields can be
reduced to an effective 2D dilaton gravity coupled nonminimally to the matter
fields. We study the leading order (tree level) vertices. The 4-particle matrix
element is calculated explicitly. It is interpreted as scattering with
formation of a virtual black hole state. As one novel feature we predict the
gravitational decay of s-waves.Comment: 9 pages, 1 figure, added clarifying comments in the introduction, the
conclusion, and the virtual black hole sectio
Markovian Dynamics of Josephson Parametric Amplification
In this work, we derive the dynamics of the lossy DC pumped non-degenerate
Josephson parametric amplifier (DCPJPA). The main element in a DCPJPA is the
superconducting Josephson junction. The DC bias generates the AC Josephson
current varying the nonlinear inductance of the junction. By this way the
Josephson junction acts as the pump oscillator as well as the time varying
reactance of the parametric amplifier. In quantum-limited amplification,
losses and noise have an increased impact on the characteristics of an
amplifier. We outline the classical model of the lossy DCPJPA and derive the
available noise power spectral densities. A classical treatment is not
capable of including properties like spontaneous emission which is mandatory
in case of amplification at the quantum limit. Thus, we derive a quantum
mechanical model of the lossy DCPJPA. Thermal losses are modeled by the
quantum Langevin approach, by coupling the quantized system to a photon heat
bath in thermodynamic equilibrium. The mode occupation in the bath follows
the Bose-Einstein statistics. Based on the second quantization formalism, we
derive the Heisenberg equations of motion of both resonator modes. We assume
the dynamics of the system to follow the Markovian approximation, i.e. the
system only depends on its actual state and is memory-free. We explicitly
compute the time evolution of the contributions to the signal mode energy and
give numeric examples based on different damping and coupling constants. Our
analytic results show, that this model is capable of including thermal noise
into the description of the DC pumped non-degenerate Josephson parametric
amplifier
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