2,544 research outputs found
Universal properties of distorted Kerr-Newman black holes
We discuss universal properties of axisymmetric and stationary configurations
consisting of a central black hole and surrounding matter in Einstein-Maxwell
theory. In particular, we find that certain physical equations and inequalities
(involving angular momentum, electric charge and horizon area) are not
restricted to the Kerr-Newman solution but can be generalized to the situation
where the black hole is distorted by an arbitrary axisymmetric and stationary
surrounding matter distribution.Comment: 7 page
Bulk and surface magnetoinductive breathers in binary metamaterials
We study theoretically the existence of bulk and surface discrete breathers
in a one-dimensional magnetic metamaterial comprised of a periodic binary array
of split-ring resonators. The two types of resonators differ in the size of
their slits and this leads to different resonant frequencies. In the framework
of the rotating-wave approximation (RWA) we construct several types of breather
excitations for both the energy-conserved and the dissipative-driven systems by
continuation of trivial breather solutions from the anticontinuous limit to
finite couplings. Numerically-exact computations that integrate the full model
equations confirm the quality of the RWA results. Moreover, it is demonstrated
that discrete breathers can spontaneously appear in the dissipative-driven
system as a results of a fundamental instability.Comment: 10 pages, 16 figure
Field of homogeneous Plane in Quantum Electrodynamics
We study quantum electrodynamics coupled to the matter field on singular
background, which we call defect. For defect on the infinite plane we
calculated the fermion propagator and mean electromagnetic field. We show that
at large distances from the defect plane, the electromagnetic field is constant
what is in agreement with the classical results. The quantum corrections
determining the field near the plane are calculated in the leading order of
perturbation theory.Comment: 16 page
Non-existence of stationary two-black-hole configurations
We resume former discussions of the question, whether the spin-spin repulsion
and the gravitational attraction of two aligned black holes can balance each
other. To answer the question we formulate a boundary value problem for two
separate (Killing-) horizons and apply the inverse (scattering) method to solve
it. Making use of results of Manko, Ruiz and Sanabria-G\'omez and a novel black
hole criterion, we prove the non-existence of the equilibrium situation in
question.Comment: 15 pages, 3 figures; Contribution to Juergen Ehlers Memorial Issue
(GeRG journal
Effects of bovine colostrum on performance, survival, and immunoglobulin status of suckling piglets during the first days of life
Supplementation of bovine colostrum (BC) has shown to improve growth performance, intestinal development, and immune response in early-weaned pigs. Little is known about whether BC may have similar effects in neonatal piglets. In the present study, the effect of BC supplementation on mortality, growth performance, and blood parameters (plasma proteins and white blood count) of suckling piglets in the first 10 days of life was investigated under practical conditions with special emphasis on low birth weight piglets. In total, 258 newborn piglets from 30 multiparous sows in a commercial breeding unit were randomly assigned to two different treatment groups. Piglets received either 1 ml of BC orally on days 1-3 of life (group BC, n = 128) or 1 ml of saline (0.9%) (control (CON) group; n = 130). Body weight was measured on days 1, 4, and 10 of life. Blood was collected on days 1 and 4 from 60 piglets per group. No differences in mortality, body weight, and average daily weight gain were observed between treatment groups in days 1-10. However, compared to CON, particularly in low birth weight piglets the administration of BC supported (P < 0.01) their survival. Group BC exhibited lower plasma total protein (P = 0.03) and beta-globulin (P = 0.02) concentrations compared to group CON. In conclusion, BC improved low and normal birth weight piglets' survival during their first 10 days of life. Further research is needed to clarify whether the survival rate is related to earlier gut closure indicated by lower plasma protein levels, which might be beneficial due to a lower uptake of potential antigenic substances
Effects of bovine colostrum on performance, survival, and immunoglobulin status of suckling piglets during the first days of life
Supplementation of bovine colostrum (BC) has shown to improve growth performance, intestinal development, and immune response in early-weaned pigs. Little is known about whether BC may have similar effects in neonatal piglets. In the present study, the effect of BC supplementation on mortality, growth performance, and blood parameters (plasma proteins and white blood count) of suckling piglets in the first 10 days of life was investigated under practical conditions with special emphasis on low birth weight piglets. In total, 258 newborn piglets from 30 multiparous sows in a commercial breeding unit were randomly assigned to two different treatment groups. Piglets received either 1 ml of BC orally on days 1-3 of life (group BC, n = 128) or 1 ml of saline (0.9%) (control (CON) group; n = 130). Body weight was measured on days 1, 4, and 10 of life. Blood was collected on days 1 and 4 from 60 piglets per group. No differences in mortality, body weight, and average daily weight gain were observed between treatment groups in days 1-10. However, compared to CON, particularly in low birth weight piglets the administration of BC supported (P < 0.01) their survival. Group BC exhibited lower plasma total protein (P = 0.03) and beta-globulin (P = 0.02) concentrations compared to group CON. In conclusion, BC improved low and normal birth weight piglets' survival during their first 10 days of life. Further research is needed to clarify whether the survival rate is related to earlier gut closure indicated by lower plasma protein levels, which might be beneficial due to a lower uptake of potential antigenic substances
Non-existence of stationary two-black-hole configurations: The degenerate case
In a preceding paper we examined the question whether the spin-spin repulsion
and the gravitational attraction of two aligned sub-extremal black holes can
balance each other. Based on the solution of a boundary value problem for two
separate (Killing-) horizons and a novel black hole criterion we were able to
prove the non-existence of the equilibrium configuration in question. In this
paper we extend the non-existence proof to extremal black holes.Comment: 18 pages, 2 figure
Switching of Discrete Solitons in Engineered Waveguide Arrays
We demonstrate a simple method for controlling nonlinear switching of
discrete solitons in arrays of weakly coupled optical waveguides, for both
cubic and uadratic nonlinearities. Based on the effective discrete nonlinear
equations describing the waveguide arrays in the tight-binding approximation,
we develop the concept of the array engineering by means of a step-like
variation of the waveguide coupling. We demonstrate the digitized switching of
a narrow input beam for up to eleven neighboring waveguides, in the case of the
cubic nonlinearity, and up to ten waveguides, in the case of quadratic
nonlinearity. We discuss our predictions in terms of the physics of the
engineered Peierls-Nabarro (PN) potential experienced by strongly localized
nonlinear modes moving in a lattice and calculate, for the first time, the PN
potential for the quadratic nonlinear array. We also confirm our concept and
major findings for a full-scaled continuous model and realistic parameters, by
means of the beam propagation method.Comment: 9 pages, 8 figures, to be submitted to Physical review
Hygroscopic growth and activation of HULIS particles: experimental data and a new iterative parameterization scheme for complex aerosol particles
International audienceThe hygroscopic growth and activation of two HULIS and one Aerosol-Water-Extract sample, prepared from urban-type aerosol, were investigated. All samples were extracted from filters, redissolved in water and atomized for the investigations presented here. The hygroscopic growth measurements were done using LACIS (Leipzig Aerosol Cloud Interaction Simulator) together with a HH-TDMA (High Humidity Tandem Differential Mobility Analyzer). Hygroscopic growth was determined for relative humidities up to 99.75%. The critical diameters for activation were measured using LACIS for supersaturations between 2 and 10 per mill. All three samples showed a similar hygroscopic growth behaviour, and the two HULIS samples also were similar in their activation behavior, while the Aerosol-Water-Extract turned out to be more CCN active than the HULIS samples. The experimental data was used to derive parameterizations for the hygroscopic growth and activation of HULIS particles. The concept of ?ion (Wex et al., 2007a) and the Szyszkowski-equation (Szyszkowski, 1908; Facchini et al., 1999) were used for parameterizing the Raoult and the Kelvin (surface tension) terms of the Köhler equation, respectively. This concept proved to be very successful for the HULIS samples in the saturation range from relative humidities larger than 98% up to activation. However it failed for the Aerosol-Water extract
A Study of The Formation of Stationary Localized States Due to Nonlinear Impurities Using The Discrete Nonlinear Schr\"odinger Equation
The Discrete Nonlinear Schrdinger Equation is used to study the
formation of stationary localized states due to a single nonlinear impurity in
a Caley tree and a dimeric nonlinear impurity in the one dimensional system.
The rotational nonlinear impurity and the impurity of the form where is arbitrary and is the nonlinearity
parameter are considered. Furthermore, represents the absolute
value of the amplitude. Altogether four cases are studies. The usual Greens
function approach and the ansatz approach are coherently blended to obtain
phase diagrams showing regions of different number of states in the parameter
space. Equations of critical lines separating various regions in phase diagrams
are derived analytically. For the dimeric problem with the impurity , three values of , namely, , at and and
for are obtained. Last two values are lower than the
existing values. Energy of the states as a function of parameters is also
obtained. A model derivation for the impurities is presented. The implication
of our results in relation to disordered systems comprising of nonlinear
impurities and perfect sites is discussed.Comment: 10 figures available on reques
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