8,566 research outputs found
Finite-Size-Scaling at the Jamming Transition: Corrections to Scaling and the Correlation Length Critical Exponent
We carry out a finite size scaling analysis of the jamming transition in
frictionless bi-disperse soft core disks in two dimensions. We consider two
different jamming protocols: (i) quench from random initial positions, and (ii)
quasistatic shearing. By considering the fraction of jammed states as a
function of packing fraction for systems with different numbers of particles,
we determine the spatial correlation length critical exponent ,
and show that corrections to scaling are crucial for analyzing the data. We
show that earlier numerical results yielding are due to the improper
neglect of these corrections.Comment: 5 pages, 4 figures -- slightly revised version as accepted for Phys.
Rev. E Rapid Communication
Dyonic black holes: The theory of two electromagnetic potentials. II
The results obtained in our previous paper are now extended to the case of
stationary axially symmetric dyonic black boles within the theory of two
electromagnetic potentials. We slightly enlarge the classical Ernst formalism
by introducing, with the aid of the - and -components of the dual
potential , the magnetic potential which, similar to the known
electric potential , also takes constant value on the black hole
horizon. We analyze in detail the case of the dyonic Kerr-Newman black hole and
show how the Komar mass must be evaluated correctly in this stationary dyonic
model. In particular, we rigorously prove the validity of the standard
Tomimatsu mass formula and point out that attempts to "improve" it made in
recent years are explained by misunderstanding of the auxiliary role that
singular potentials play in the description of magnetic charges. Our approach
is symmetrical with respect to electric and magnetic charges and, like in the
static case considered earlier, Dirac strings of all kind are excluded from the
physical picture of the stationary black hole dyonic spacetimes.Comment: 14 pages, no figure
Dyonic black holes: The theory of two electromagnetic potentials
In the present paper we argue that the dyonic black hole spacetimes must be
studied within the theory of two electromagnetic potentials, and we use the
dyonic Reissner-Nordstr\"om solution to demonstrate that the field of the
monopole magnetic charge is correctly described by the -component of the
dual electromagnetic potential. As a result, the Dirac string associated with
the -component of the usual electromagnetic 4-potential becomes just a
mathematical object, without any physical content, that arises in some
calculations when one employs unsymmetrical representations of the
electromagnetic field. We use three different, though equivalent, forms of the
electromagnetic energy-momentum tensor to calculate the Komar mass of the
Reissner-Nordstr\"om black hole, and in one case the Dirac string is linked to
the magnetic charge, in another to the electric charge, while the third,
symmetrical case, is string-free.Comment: 11 pages, no figure
Use and Protection of GPS Sidelobe Signals for Enhanced Navigation Performance in High Earth Orbit
The application of the Global Positioning System (GPS) for navigation of spacecraft in High and Geosynchronous Earth Orbit (HEO/GEO) has crossed a threshold and is now being employed in operational missions. Utilizing advanced GPS receivers optimized for these missions, space users have made extensive use of the sidelobe transmissions from the GPS satellites to realize navigation performance that far exceeds that predicted by pre-launch simulations. Unfortunately, the official specification for the GPS Space Service Volume (SSV), developed in 2006, assumes that only signals emanating from the main beam of the GPS transmit antenna are useful for navigation, which greatly under-estimates the number of signals available for navigation purposes. As a result, future high-altitude space users may be vulnerable to any GPS design changes that suppress the sidelobe transmissions, beginning with Block III space vehicles (SVs) 11-32. This paper presents proposed changes to the GPS system SSV requirements, as informed by data from recent experiments in the SSV and new mission applications that are enabled by GPS navigation in HEO/GEO regimes. The NASA/NOAA GOES-R series satellites are highlighted as an example of a mission that relies on this currently-unspecified GPS system performance to meet mission requirements
Different Harvest Schedules to Prepare Deferred Forage from C4 Grasses in Córdoba, Argentina
From 1995 until 1999 a trial was done in the fields of the Universidad Nacional de Córdoba with four C4 forage grasses. These fields lie in the subtropical and semiarid region of Argentina. This research aimed to identify forage species that could be used as deferred forage for the drier and cooler winter season. Four species of C4 grasses were used: Rhodesgrass (Chloris gayana Kunth), Gatton (Panicum maximum), coloratum (Panicum coloratum) and digitgrass (Digitaria eriantha), respectively. Two growing periods were used: full season growth (FS) and half season regrowth (HS), in both cases the deferred forage was harvested three times: at the beginning, in the middle and at the end of the winter. This paper foccuses DM yields in kg/hectare (DM) and percentage of crude protein (CP). The HS yields less but shows better CP than the FS, therefore it may be a better forage in winter. Coloratum and digigrass seems to give better deferred forage than the other species
Influence of amount and percentage of CXCR4-using virus in predicting week 48 responses to maraviroc in treatment-naïve patients
Enteric helminths promote Salmonella co-infection by altering the intestinal metabolome
Intestinal helminth infections occur pre dominantly in regions where exposure to enteric bacterial pathogens is also common. Helminth infections inhibit host immunity against microbial pathogens, which has largely been attributed to the induction of regulatory or type 2 (Th2) immune responses. Here we demonstrate an additional three-way interaction in which helminth infection alters the metabolic environment of the host intestine to enhance bacterial pathogenicity. We show that an ongoing helminth infection increased colonization by Salmonella independently of T regulatory or Th2 cells. Instead, helminth infection altered the metabolic profile of the intestine, which directly enhanced bacterial expression of Salmonella pathogenicity island 1 (SPI-1) genes and increased intracellular invasion. These data reveal a novel mechanism by which a helminth-modified metabolome promotes susceptibility to bacterial co-infection
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