701 research outputs found
Effective Actions for the SU(2) Confinement-Deconfinement Phase Transition
We compare different Polyakov loop actions yielding effective descriptions of
finite-temperature SU(2) Yang-Mills theory on the lattice. The actions are
motivated by a simultaneous strong-coupling and character expansion obeying
center symmetry and include both Ising and Ginzburg-Landau type models. To keep
things simple we limit ourselves to nearest-neighbor interactions. Some
truncations involving the most relevant characters are studied within a novel
mean-field approximation. Using inverse Monte-Carlo techniques based on exact
geometrical Schwinger-Dyson equations we determine the effective couplings of
the Polyakov loop actions. Monte-Carlo simulations of these actions reveal that
the mean-field analysis is a fairly good guide to the physics involved. Our
Polyakov loop actions reproduce standard Yang-Mills observables well up to
limitations due to the nearest-neighbor approximation.Comment: 14 pages, 10 figures, v2: typos correcte
Chicory roots improves the taste and odour of organic pork
The carbohydrate inulin is known to reduce the production of skatole in pigs. This is caused by inulin changing the intestinal flora, so that the bacteria that produce skatole are held in check. This change in intestinal flora also reduces the number of intestinal parasites in the pigs. However the high cost of inulin makes its use in pig feed impractical.
Chicory root contains inulin and a series of other carbohydrates and secondary metabolites. Therefore we have examined whether chicory root can replace pure inulin and thereby reduce boar taint, improve the taste of pork and reduce the infection of pigs with pathogenic parasites and bacteria
Bi-Polaron and N-Polaron Binding Energies
The binding of polarons, or its absence, is an old and subtle topic. Here we
prove two things rigorously. First, the transition from many-body collapse to
the existence of a thermodynamic limit for N polarons occurs precisely at
U=2\alpha, where U is the electronic Coulomb repulsion and \alpha is the
polaron coupling constant. Second, if U is large enough, there is no
multi-polaron binding of any kind. Considering the known fact that there is
binding for some U>2\alpha, these conclusions are not obvious and their proof
has been an open problem for some time.Comment: 4 page
Validation of vertical ground reaction forces on individual limbs calculated from kinematics of horse locomotion
The purpose of this study was to determine whether individual limb forces could be calculated accurately from kinematics of trotting and walking horses. We collected kinematic data and measured vertical ground reaction forces on the individual limbs of seven Warmblood dressage horses, trotting at 3.4 m
Path-decomposition expansion and edge effects in a confined magnetized free-electron gas
Path-integral methods can be used to derive a `path-decomposition expansion'
for the temperature Green function of a magnetized free-electron gas confined
by a hard wall. With the help of this expansion the asymptotic behaviour of the
profiles for the excess particle density and the electric current density far
from the edge is determined for arbitrary values of the magnetic field
strength. The asymptotics are found to depend sensitively on the degree of
degeneracy. For a non-degenerate electron gas the asymptotic profiles are
essentially Gaussian (albeit modulated by a Bessel function), on a length scale
that is a function of the magnetic field strength and the temperature. For a
completely degenerate electron gas the asymptotic behaviour is again
proportional to a Gaussian, with a scale that is the magnetic length in this
case. The prefactors are polynomial and logarithmic functions of the distance
from the wall, that depend on the number of filled Landau levels . As a
consequence, the Gaussian asymptotic decay sets in at distances that are large
compared to the magnetic length multiplied by .Comment: 16 pages, 2 figures, submitted to J. Phys. A: Math. Gen; corrected
small typ
The effect of a diet with fructan-rich chicory roots on intestinal helminths and microbiota with special focus on Bifidobacteria and Campylobacter in piglets around weaning
The restrictions on the use of antibiotic and anthelmintic treatments in organic pig farming necessitate alternative non-medical control strategies. Therefore, the antibiotic and parasite-reducing effect of a fructan-rich (prebiotic) diet of dried chicory was investigated in free-ranging piglets. Approximately half of 67 piglets from 9 litters were experimentally infected with Ascaris suum and Trichuris suis in the suckling period (1 to 7 weeks of age) and 58 of the piglets were challenged daily with E. coli O138:F8 for 9 days after weaning to induce weaning diarrhoea. The litters were fed either chicory (30% DM) or a control diet. The effect of chicory on intestinal helminths, intestinal microbiota, especially Bifidobacteria and Campylobacter spp., and E. coli post-weaning diarrhoea was assessed. The weight gain of the piglets was not impaired significantly by chicory. The intestinal A. suum worm burden was reduced by 64% (P=0.034) in the chicory-fed piglets, whereas these same piglets had 63% more T. suis worms (P=0.016). Feeding with chicory elicited no changes among the main bacterial groups in ileum according to terminal restriction fragment length polymorphism (T-RFLP) analysis. However, the terminal-restriction fragment (T-RF) 208 bp, which may belong to Lachnospiraceae, was stimulated by the chicory feed (P=0.03), and T-RF 370 bp that matches Enterobacter belonging to the Enterobacteria was reduced (P=0.004). Additionally, chicory increased the level of Bifidobacteria (P=0.001) and the faecal Campylobacter excretion level was transitorily reduced in chicory-fed piglets at 7 weeks of age (P=0.029). Unfortunately, it was not possible to assess the effect of chicory on post-weaning diarrhoea as it did not develop. In conclusion, feeding piglets chicory around the time of weaning caused complex changes of the microbiota and parasite communities within the intestinal tract, and feeding piglets chicory may therefore serve as an animal-friendly strategy to control pathogens
Predictive minds in Ouija board sessions
Andersen M, Nielbo KL, Schjoedt U, Pfeiffer T, Roepstorff A, Sørensen J. Predictive minds in Ouija board sessions. Phenomenology and the Cognitive Sciences. 2018;18(3):577-588.Ouija board sessions are illustrious examples of how subjective feelings of control the Sense of Agency (SoA) - can be manipulated in real life settings. We present findings from a field experiment at a paranormal conference, where Ouija enthusiasts were equipped with eye trackers while using the Ouija board. Our results show that participants have a significantly lower probability at visually predicting letters in a Ouija board session compared to a condition in which they are instructed to deliberately spell out words with the Ouija board planchette. Our results also show that Ouija board believers report lower SoA compared to sceptic participants. These results support previous research which claim that low sense of agency is caused by a combination of retrospective inference and an inhibition of predictive processes. Our
results show that users in Ouija board sessions become increasingly better at predicting letters as responses unfold over time, and that meaningful responses from the Ouija board can only be accounted for when considering interactions that goes on at the participant pair level. These results suggest that meaningful responses from the Ouija board may be an emergent property of interacting and predicting minds that increasingly impose structure on initially random events in Ouija sessions
Relativistic diffusion processes and random walk models
The nonrelativistic standard model for a continuous, one-parameter diffusion
process in position space is the Wiener process. As well-known, the Gaussian
transition probability density function (PDF) of this process is in conflict
with special relativity, as it permits particles to propagate faster than the
speed of light. A frequently considered alternative is provided by the
telegraph equation, whose solutions avoid superluminal propagation speeds but
suffer from singular (non-continuous) diffusion fronts on the light cone, which
are unlikely to exist for massive particles. It is therefore advisable to
explore other alternatives as well. In this paper, a generalized Wiener process
is proposed that is continuous, avoids superluminal propagation, and reduces to
the standard Wiener process in the non-relativistic limit. The corresponding
relativistic diffusion propagator is obtained directly from the nonrelativistic
Wiener propagator, by rewriting the latter in terms of an integral over
actions. The resulting relativistic process is non-Markovian, in accordance
with the known fact that nontrivial continuous, relativistic Markov processes
in position space cannot exist. Hence, the proposed process defines a
consistent relativistic diffusion model for massive particles and provides a
viable alternative to the solutions of the telegraph equation.Comment: v3: final, shortened version to appear in Phys. Rev.
- …