297 research outputs found
The sense of agency as tracking control
Does sense of agency (SoA) arise merely from action-outcome associations, or does an additional real-time process track each step along the chain? Tracking control predicts that deviant intermediate steps between action and outcome should reduce SoA. In two experiments, participants learned mappings between two finger actions and two tones. In later test blocks, actions triggered a robot hand moving either the same or a different finger, and also triggered tones, which were congruent or incongruent with the mapping. The perceived delay between actions and tones gave a proxy measure for SoA. Action-tone binding was stronger for congruent than incongruent tones, but only when the robot movement was also congruent. Congruent tones also had reduced N amplitudes, but again only when the robot movement was congruent.We suggest that SoA partly depends on a real time tracking control mechanism, since deviant intermediate action of the robot reduced SoA over the tone
Introduction to the functional RG and applications to gauge theories
These lectures contain an introduction to modern renormalization group (RG)
methods as well as functional RG approaches to gauge theories. In the first
lecture, the functional renormalization group is introduced with a focus on the
flow equation for the effective average action. The second lecture is devoted
to a discussion of flow equations and symmetries in general, and flow equations
and gauge symmetries in particular. The third lecture deals with the flow
equation in the background formalism which is particularly convenient for
analytical computations of truncated flows. The fourth lecture concentrates on
the transition from microscopic to macroscopic degrees of freedom; even though
this is discussed here in the language and the context of QCD, the developed
formalism is much more general and will be useful also for other systems.Comment: 60 pages, 14 figures, Lectures held at the 2006 ECT* School
"Renormalization Group and Effective Field Theory Approaches to Many-Body
Systems", Trento, Ital
Phase Structure and Compactness
In order to study the influence of compactness on low-energy properties, we
compare the phase structures of the compact and non-compact two-dimensional
multi-frequency sine-Gordon models. It is shown that the high-energy scaling of
the compact and non-compact models coincides, but their low-energy behaviors
differ. The critical frequency at which the sine-Gordon model
undergoes a topological phase transition is found to be unaffected by the
compactness of the field since it is determined by high-energy scaling laws.
However, the compact two-frequency sine-Gordon model has first and second order
phase transitions determined by the low-energy scaling: we show that these are
absent in the non-compact model.Comment: 21 pages, 5 figures, minor changes, final version, accepted for
publication in JHE
Dissecting the Genetic Architecture of Host–Pathogen Specificity
International audienc
The Definition, Current Knowledge and Implementation of Welfare for Farm Animals--A Personal View
Being humane to farm animals (welfare) must include (1) having a sound knowledge of their normal and anomalous behavior responses in a farm context and heeding this in a practical way and (2) adopting handling procedures which elicit minimal distress in the species concerned. Building up an ethogram of predictable responses and recording the patterns of behavior during key events, mating, birth, and care of the young are essential. There are still gaps in the recorded ethograms offarm animals. Objective measurements of distress, including an index of its seriousness, are also a priority.
The results from animal preference tests can provide some answers on which to base practical husbandry in the areas of housing design, optimal temperatures, the need for companions, factors which elicit aggression, acceptable feeds, and species\u27 sensory capacities. Handling preference tests could also be undertaken. Overcoming inertia is a problem for both the owners and the animals if changes are to be made within established systems of production.
Gross cruelty can be countered by legislation, but the motivation for ongoing good welfare of farmed animals must come from within the workers/owners on the site. Trying to force it by legislation may be counter-productive. A five-point program for promoting practical animal welfare is outlined
How does it feel to act together?
This paper on the phenomenology of joint agency proposes a foray into a little explored territory at the intersection of two very active domains of research: joint action and sense of agency. I explore two ways in which our experience of joint agency may differ from our experience of individual agency. First, the mechanisms of action specification and control involved in joint action are typically more complex than those present in individual actions, since it is crucial for joint action that people coordinate their plans and actions. I discuss the implications that these coordination requirements might have for the strength of the sense of agency an agent may experience for a joint action. Second, engagement in joint action may involve a transformation of agentive identity and a partial or complete shift from a sense of self-agency to a sense of we-agency. I discuss several factors that may contribute to shaping our sense of agentive identity in joint action
On the Renormalization of Theories of a Scalar Chiral Superfield
An exact renormalization group for theories of a scalar chiral superfield is
formulated, directly in four dimensional Euclidean space. By constructing a
projector which isolates the superpotential from the full Wilsonian effective
action, it is shown that the nonperturbative nonrenormalization theorem
follows, quite simply, from the flow equation. Next, it is argued that there do
not exist any physically acceptable non-trivial fixed points. Finally, the
Wess-Zumino model is considered, as a low energy effective theory. Following an
evaluation of the one and two loop beta-function coefficients, to illustrate
the ease of use of the formalism, it is shown that the beta-function in the
massless case does not receive any nonperturbative power corrections.Comment: 52 pages, 4 figures; v2: 57 pages - refs added and some minor
corrections/clarifications made; v3: published in JHEP - some further
clarifications mad
Minimally invasive computer-navigated total hip arthroplasty, following the concept of femur first and combined anteversion: design of a blinded randomized controlled trial
<p>Abstract</p> <p>Background</p> <p>Impingement can be a serious complication after total hip arthroplasty (THA), and is one of the major causes of postoperative pain, dislocation, aseptic loosening, and implant breakage. Minimally invasive THA and computer-navigated surgery were introduced several years ago. We have developed a novel, computer-assisted operation method for THA following the concept of "femur first"/"combined anteversion", which incorporates various aspects of performing a functional optimization of the cup position, and comprehensively addresses range of motion (ROM) as well as cup containment and alignment parameters. Hence, the purpose of this study is to assess whether the artificial joint's ROM can be improved by this computer-assisted operation method. Second, the clinical and radiological outcome will be evaluated.</p> <p>Methods/Design</p> <p>A registered patient- and observer-blinded randomized controlled trial will be conducted. Patients between the ages of 50 and 75 admitted for primary unilateral THA will be included. Patients will be randomly allocated to either receive minimally invasive computer-navigated "femur first" THA or the conventional minimally invasive THA procedure. Self-reported functional status and health-related quality of life (questionnaires) will be assessed both preoperatively and postoperatively. Perioperative complications will be registered. Radiographic evaluation will take place up to 6 weeks postoperatively with a computed tomography (CT) scan. Component position will be evaluated by an independent external institute on a 3D reconstruction of the femur/pelvis using image-processing software. Postoperative ROM will be calculated by an algorithm which automatically determines bony and prosthetic impingements.</p> <p>Discussion</p> <p>In the past, computer navigation has improved the accuracy of component positioning. So far, there are only few objective data quantifying the risks and benefits of computer navigated THA. Therefore, this study has been designed to compare minimally invasive computer-navigated "femur first" THA with a conventional technique for minimally invasive THA. The results of this trial will be presented as soon as they become available.</p> <p>Trial registration number</p> <p>DRKS00000739</p
Conjectures on exact solution of three - dimensional (3D) simple orthorhombic Ising lattices
We report the conjectures on the three-dimensional (3D) Ising model on simple
orthorhombic lattices, together with the details of calculations for a putative
exact solution. Two conjectures, an additional rotation in the fourth curled-up
dimension and the weight factors on the eigenvectors, are proposed to serve as
a boundary condition to deal with the topologic problem of the 3D Ising model.
The partition function of the 3D simple orthorhombic Ising model is evaluated
by spinor analysis, by employing these conjectures. Based on the validity of
the conjectures, the critical temperature of the simple orthorhombic Ising
lattices could be determined by the relation of KK* = KK' + KK'' + K'K'' or
sinh 2K sinh 2(K' + K'' + K'K''/K) = 1. For a simple cubic Ising lattice, the
critical point is putatively determined to locate exactly at the golden ratio
xc = exp(-2Kc) = (sq(5) - 1)/2, as derived from K* = 3K or sinh 2K sinh 6K = 1.
If the conjectures would be true, the specific heat of the simple orthorhombic
Ising system would show a logarithmic singularity at the critical point of the
phase transition. The spontaneous magnetization and the spin correlation
functions of the simple orthorhombic Ising ferromagnet are derived explicitly.
The putative critical exponents derived explicitly for the simple orthorhombic
Ising lattices are alpha = 0, beta = 3/8, gamma = 5/4, delta = 13/3, eta = 1/8
and nu = 2/3, showing the universality behavior and satisfying the scaling
laws. The cooperative phenomena near the critical point are studied and the
results obtained based on the conjectures are compared with those of the
approximation methods and the experimental findings. The 3D to 2D crossover
phenomenon differs with the 2D to 1D crossover phenomenon and there is a
gradual crossover of the exponents from the 3D values to the 2D ones.Comment: 176 pages, 4 figure
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