Mutual Information of Population Codes and Distance Measures in Probability Space

We studied the mutual information between a stimulus and a large system consisting of stochastic, statistically independent elements that respond to a stimulus. The Mutual Information (MI) of the system saturates exponentially with system size. A theory of the rate of saturation of the MI is developed. We show that this rate is controlled by a distance function between the response probabilities induced by different stimuli. This function, which we term the {\it Confusion Distance} between two probabilities, is related to the Renyi $\alpha$-Information.Comment: 11 pages, 3 figures, accepted to PR

Vacuum structure of CP^N sigma models at theta=pi

We show that parity symmetry is not spontaneously broken in the CP^N sigma model for any value of N when the coefficient of the $\theta$--term becomes $\theta=\pi$ (mod $2\pi$). The result follows from a non-perturbative analysis of the nodal structure of the vacuum functional $\psi_0(z)$. The dynamical role of sphalerons turns out to be very important for the argument. The result introduces severe constraints on the possible critical behavior of the models at $\theta=\pi$ (mod $2\pi$).Comment: 8 pages, revtex, to appear in Phys. Rev. Let

Setting the scale for the Luescher-Weisz action

We study the quark-antiquark potential of quenched SU(3) lattice gauge theory with the Luescher-Weisz action. After blocking the gauge fields with the recently proposed hypercubic transformation we compute the Sommer parameter, extract the lattice spacing a and set the scale at 6 different values of the gauge coupling in a range from a = 0.084 fm to 0.136 fm.Comment: Remarks and references added, to appear in Phys. Rev.

Observational evidence confirms modelling of the long-term integrity of CO2-reservoir caprocks

Anthropogenic CO2 storage, where CO2 is injected into saline geological resevoirs, relies on an impermeable caprock to seal in the CO2, but caprock reaction rates to CO2 acid brines are unclear

Chiral symmetry restoration and the Z3 sectors of QCD

Quenched SU(3) lattice gauge theory shows three phase transitions, namely the chiral, the deconfinement and the Z3 phase transition. Knowing whether or not the chiral and the deconfinement phase transition occur at the same temperature for all Z3 sectors could be crucial to understand the underlying microscopic dynamics. We use the existence of a gap in the Dirac spectrum as an order parameter for the restoration of chiral symmetry. We find that the spectral gap opens up at the same critical temperature in all Z3 sectors in contrast to earlier claims in the literature.Comment: 4 pages, 4 figure

Yang-Mills Theory as a Deformation of Topological Field Theory, Dimensional Reduction and Quark Confinement

We propose a reformulation of Yang-Mills theory as a perturbative deformation of a novel topological (quantum) field theory. We prove that this reformulation of the four-dimensional QCD leads to quark confinement in the sense of area law of the Wilson loop. First, Yang-Mills theory with a non-Abelian gauge group G is reformulated as a deformation of a novel topological field theory. Next, a special class of topological field theories is defined by both BRST and anti-BRST exact action corresponding to the maximal Abelian gauge leaving the maximal torus group H of G invariant. Then we find the topological field theory ($D>2$) has a hidden supersymmetry for a choice of maximal Abelian gauge. As a result, the D-dimensional topological field theory is equivalent to the (D-2)-dimensional coset G/H non-linear sigma model in the sense of Parisi and Sourlas dimensional reduction. After maximal Abelian gauge fixing, the topological property of magnetic monopole and anti-monopole of four-dimensional Yang-Mills theory is translated into that of instanton and anti-instanton in two-dimensional equivalent model. It is shown that the linear static potential in four-dimensions follows from the instanton--anti-instanton gas in the equivalent two-dimensional non-linear sigma model obtained from the four-dimensional topological field theory by dimensional reduction, while the remaining Coulomb potential comes from the perturbative part in four-dimensional Yang-Mills theory. The dimensional reduction opens a path for applying various exact methods developed in two-dimensional quantum field theory to study the non-perturbative problem in low-energy physics of four-dimensional quantum field theories.Comment: 58 pages, Latex, no figures, version accepted for publication in Phys. Rev. D (additions of Discussion, references and minor changes

Vooronderzoek data en methoden illegalenschatting

The purpose of this preliminary study is to assess the practical suitability, usefulness, and availability of supplementary data and methods for conducting an estimation of illegals.Dit is vooronderzoek naar de beschikbare data en methoden voor het schatten van het aantal illegalen in Nederland. Doel van de voorstudie is de praktische geschiktheid, bruikbaarheid en beschikbaarheid van aanvullende data en methoden voor het uitvoeren van een illegalenschatting na te gaan. Voor eerdere schattingen van het aantal illegaal in Nederland verblijvende vreemdelingen is gebruik gemaakt van de vangst-hervangstmethode op basis van één registratie. Voor de registratie is gebruik gemaakt van staande houdingen van illegalen door de politie, bijvoorbeeld omdat zij illegaal aan het werk zijn of misdrijven plegen.Het onderzoek is opgedeeld in twee verschillende onderdelen. In het eerste deel ligt de focus op het inventariseren van de beschikbare schattingsmethoden, terwijl het tweede deel is gericht op het in kaart brengen van de potentiële databronnen. De opbrengsten van beide delen zijn in samenhang bezien om tot een overzicht van de meeste kansrijke schattingsmethoden te komen wanneer rekening wordt gehouden met beschikbaarheid, bruikbaarheid en toegankelijkheid van de potentiële databronnen

Onderzoek justitieel interventiepalet kindermishandeling

This research has three goals. The first goal is to gain insight into the interventions and resources that can be used within the justice system for perpetrators and victims of child abuse, the decisionmaking process concerning the use of these interventions, and the frequency with which the interventions are deployed. The second goal of this research is to determine whether the intervention palette is adequate for all types of perpetrators and victims, and whether suitable interventions and resources are available for all types of perpetrators and victims. The third goal is to examine to what extent the current intervention palette is in line with recent scientific developments in the investigation into child abuse.Het onderzoek heeft de volgende probleemstelling: Wat is de bestaande situatie omtrent interventies en middelen voor plegers en slachtoffers van kindermishandeling binnen de justitieketen in termen van beschikbaarheid van interventies en middelen, frequentie van toepassing, besluitvorming omtrent inzet en de toereikendheid met betrekking tot de beschikbaarheid van geschikte interventies en middelen voor alle typen plegers en slachtoffers? En in hoeverre sluit het interventiepalet aan bij recente wetenschappelijke ontwikkelingen, waaronder nieuwe inzichten uit de sociale neurowetenschappen? INHOUD: 1. Inleiding 2. Definities 3. Kenmerken slachtoffers en plegers 4. Bestaande interventies 5. Multidisciplinaire samenwerking 6. Conclusie

Individual and common patterns in the order of symptom improvement during outpatient treatment for major depression

BACKGROUND: Research so far provided few clues on the order in which depressive symptoms typically remit during treatment. This study examined which depressive symptoms improve first, and whether symptoms changed before, simultaneous with, or after the core symptoms of depression (i.e., sad mood, loss of pleasure, and loss of interest).METHODS: Participants were 176 patients with Major Depressive Disorder (MDD) receiving outpatient treatment (a combination of pharmacotherapy and psychological interventions) for depression. Participants filled out the Inventory of Depressive Symptomatology - Self Report (IDS-SR) for 16 to 20 consecutive weeks. For each symptom, the timing of onset of a persistent improvement was determined for each single-subject separately.RESULTS: Which symptoms improved first differed markedly across patients. The core depression symptoms improved 1.5 to 2 times more often before (48% - 60%) than after (19% -28%) depressive cognitions ('view of myself' and 'view of the future'), anxiety symptoms ('feeling irritable' and 'feeling anxious / tense') and vegetative symptoms ('loss of energy', 'slowed down', and 'physical energy'). Only improvements in suicidal thoughts were more likely to occur before (46% - 48%) than after (29%) improvements in the depression core symptoms.LIMITATIONS: Not all 'core depression-non-core symptom' combinations could be tested because some symptoms did not improve in a sufficient number of patients.CONCLUSIONS: Which improvements mark the start of symptom remission differed between patients. Improvements in the core depression symptoms 'sad mood', 'loss of interest', and 'loss of pleasure' were more likely to occur before than after improvements in non-core symptoms.</p