2,147 research outputs found
Dobrushin-Kotecky-Shlosman theorem for polygonal Markov fields in the plane
We consider the so-called length-interacting Arak-Surgailis polygonal Markov
fields with V-shaped nodes - a continuum and isometry invariant process in the
plane sharing a number of properties with the two-dimensional Ising model. For
these polygonal fields we establish a low-temperature phase separation theorem
in the spirit of the Dobrushin-Kotecky-Shlosman theory, with the corresponding
Wulff shape deteremined to be a disk due to the rotation invariant nature of
the considered model. As an important tool replacing the classical cluster
expansion techniques and very well suited for our geometric setting we use a
graphical construction built on contour birth and death process, following the
ideas of Fernandez, Ferrari and Garcia.Comment: 59 pages, new version revised according to the referee's suggestions
and now publishe
Dianthracenylazatrioxa[8]circulene: synthesis, characterization and application in OLEDs
A soluble, green-blue fluorescent, pi-extended azatrioxa[8]circulene was synthesized by oxidative condensation of a 3,6-dihydroxycarbazole and 1,4-anthraquinone by using benzofuran scaffolding. This is the first circulene to incorporate anthracene within its carbon framework. Solvent-dependent fluorescence and bright green electroluminescence accompanied by excimer emission are the key optical properties of this material. The presence of sliding pi-stacked columns in the single crystal of dianthracenylazatrioxa[8]circulene is found to cause a very high electron-hopping rate, thus making this material a promising n-type organic semiconductor with an electron mobility predicted to be around 2.26 cm(2) V-1 s(-1). The best organic light-emitting diode (OLED) device based on the dianthracenylazatrioxa[8]circulene fluorescent emitter has a brightness of around 16 000 Cd m(-2) and an external quantum efficiency of 3.3 %. Quantum dot-based OLEDs were fabricated by using dianthracenylazatrioxa[8]circulene as a host matrix material.Peer reviewe
On the partial connection between random matrices and interacting particle systems
In the last decade there has been increasing interest in the fields of random
matrices, interacting particle systems, stochastic growth models, and the
connections between these areas. For instance, several objects appearing in the
limit of large matrices arise also in the long time limit for interacting
particles and growth models. Examples of these are the famous Tracy-Widom
distribution functions and the Airy_2 process. The link is however sometimes
fragile. For example, the connection between the eigenvalues in the Gaussian
Orthogonal Ensembles (GOE) and growth on a flat substrate is restricted to
one-point distribution, and the connection breaks down if we consider the joint
distributions. In this paper we first discuss known relations between random
matrices and the asymmetric exclusion process (and a 2+1 dimensional
extension). Then, we show that the correlation functions of the eigenvalues of
the matrix minors for beta=2 Dyson's Brownian motion have, when restricted to
increasing times and decreasing matrix dimensions, the same correlation kernel
as in the 2+1 dimensional interacting particle system under diffusion scaling
limit. Finally, we analyze the analogous question for a diffusion on (complex)
sample covariance matrices.Comment: 31 pages, LaTeX; Added a section concerning the Markov property on
space-like path
Differences and overlap in self-reported symptoms of bipolar disorder and borderline personality disorder
Background: Differential diagnosis between bipolar disorder (BD) and borderline personality disorder (BPD) is often challenging due to some overlap in symptoms and comorbidity of disorders. We investigated correlations in self-reported symptoms of BD and BPD in screening questionnaires at the levels of both total scores and individual items and explored overlapping dimensions. Methods: The McLean Screening Instrument (MSI) for BPD and the Mood Disorder Questionnaire (MDQ) for BD were filled in by patients with unipolar and bipolar mood disorders (n = 313) from specialized psychiatric care within a pilot study of the Helsinki University Psychiatric Consortium. Pearson's correlation coefficients between total scores and individual items of the MSI and the MDQ were estimated. Relationships between MDQ and MSI were evaluated by exploratory factor analysis (EFA). Results: The correlation between total scores of the MDQ and MSI was moderate (r = 0.431, P <0.001). Significant correlations were found between the MSI items of "impulsivity'' and "mood instability'' and all MDQ items (P <0.01). In the EFA, the MSI "impulsivity'' and "mood instability'' items had significant cross-loadings (0.348 and 0.298, respectively) with the MDQ factor. The MDQ items of "irritability'', "flight of thoughts'' and "distractibility'' (0.280, 0.210 and 0.386, respectively) cross-loaded on the MSI factor. Conclusions: The MDQ and MSI items of "affective instability'', "impulsivity'', "irritability'', "flight of thoughts'' and "distractibility'' appear to overlap in content. The other scale items are more disorder-specific, and thus, may help to distinguish BD and BPD. (C) 2015 Elsevier Masson SAS. All rights reserved.Peer reviewe
Optimization of supply diversity for the self-assembly of simple objects in two and three dimensions
The field of algorithmic self-assembly is concerned with the design and
analysis of self-assembly systems from a computational perspective, that is,
from the perspective of mathematical problems whose study may give insight into
the natural processes through which elementary objects self-assemble into more
complex ones. One of the main problems of algorithmic self-assembly is the
minimum tile set problem (MTSP), which asks for a collection of types of
elementary objects (called tiles) to be found for the self-assembly of an
object having a pre-established shape. Such a collection is to be as concise as
possible, thus minimizing supply diversity, while satisfying a set of stringent
constraints having to do with the termination and other properties of the
self-assembly process from its tile types. We present a study of what we think
is the first practical approach to MTSP. Our study starts with the introduction
of an evolutionary heuristic to tackle MTSP and includes results from extensive
experimentation with the heuristic on the self-assembly of simple objects in
two and three dimensions. The heuristic we introduce combines classic elements
from the field of evolutionary computation with a problem-specific variant of
Pareto dominance into a multi-objective approach to MTSP.Comment: Minor typos correcte
The blue vibronically resolved electroluminescence of azatrioxa[8]circulene
Organic Light Emitting Dioides (OLED)devices were fabricated with blue emission based on azatrioxa[8]circulene and 4,4-N,N'-Dicarbazolyl-1,1'-biphenyl (CBP) with maximum brightness of 840 kd/m(2) at 12 V and the starting voltage of 3.5 V. The vibronic emission spectrum was analyzed by the promotive modes calculation method. The electroluminescence of fabricated OLED device is caused by the 0-0 electronic transition and single excitations of 1473 cm(-1) and 1673 cm(-1) modes and combinations thereof.Peer reviewe
Vicious Walkers and Hook Young Tableaux
We consider a generalization of the vicious walker model. Using a bijection
map between the path configuration of the non-intersecting random walkers and
the hook Young diagram, we compute the probability concerning the number of
walker's movements. Applying the saddle point method, we reveal that the
scaling limit gives the Tracy--Widom distribution, which is same with the limit
distribution of the largest eigenvalues of the Gaussian unitary ensemble.Comment: 23 pages, 5 figure
Anxiety symptoms in a major mood and schizophrenia spectrum disorders
Background: Comorbid anxiety symptoms and disorders are present in many psychiatric disorders, but methodological variations render comparisons of their frequency and intensity difficult. Furthermore, whether risk factors for comorbid anxiety symptoms are similar in patients with mood disorders and schizophrenia spectrum disorders remains unclear. Methods: The Overall Anxiety Severity and Impairment Scale (OASIS) was used to measure anxiety symptoms in psychiatric care patients with schizophrenia or schizoaffective disorder (SSA, n = 113), bipolar disorder (BD, n = 99), or depressive disorder (DD, n = 188) in the Helsinki University Psychiatric Consortium Study. Bivariate correlations and multivariate linear regression models were used to examine associations of depressive symptoms, neuroticism, early psychological trauma and distress, self-efficacy, symptoms of borderline personality disorder, and attachment style with anxiety symptoms in the three diagnostic groups. Results: Frequent or constant anxiety was reported by 40.2% of SSA, 51.5% of BD, and 55.6% of DD patients; it was described as severe or extreme by 43.8%, 41.4%, and 41.2% of these patients, respectively. SSA patients were significantly less anxious (P = 0.010) and less often avoided anxiety-provoking situations (P = 0.009) than the other patients. In regression analyses, OASIS was associated with high neuroticism, symptoms of depression and borderline personality disorder and low self-efficacy in all patients, and with early trauma in patients with mood disorders. Conclusions: Comorbid anxiety symptoms are ubiquitous among psychiatric patients with mood or schizophrenia spectrum disorders, and in almost half of them, reportedly severe. Anxiety symptoms appear to be strongly related to both concurrent depressive symptoms and personality characteristics, regardless of principal diagnosis. (C) 2016 Elsevier Masson SAS. All rights reserved.Peer reviewe
Self-reported symptoms of schizotypal and borderline personality disorder in patients with mood disorders
Background: Distinguishing between symptoms of schizotypal (SPD) and borderline personality disorders (BPD) is often difficult due to their partial overlap and frequent co-occurrence. We investigated correlations in self-reported symptoms of SPD and BPD in questionnaires at the levels of both total scores and individual items, examining overlapping dimensions. Methods: Two questionnaires, the McLean Screening Instrument (MSI) for BPD and the Schizotypal Personality Questionnaire Brief (SPQ-B) for SPD, were filled in by patients with mood disorders (n = 282) from specialized psychiatric care in a study of the Helsinki University Psychiatric Consortium. Correlation coefficients between total scores and individual items of the MSI and SPQ-B were estimated. Multivariate regression analysis (MRA) was conducted to examine the relationships between SPQ-B and MSI. Results: The Spearman's correlation between total scores of the MSI and SPQ-B was strong (rho = 0.616, P <0.005). Items of MSI reflecting disrupted relatedness and affective dysregulation correlated moderately (r(phi) varied between 0.2 and 0.4, P <0.005) with items of SPQ. Items of MSI reflecting behavioural dysregulation correlated only weakly with items of SPQ. In MRA, depressive symptoms, sex and MSI were significant predictors of SPQ-B score, whereas symptoms of anxiety, age and SPQ-B were significant predictors of MSI score. Conclusions: Items reflecting cognitive-perceptual distortions and affective symptoms of BPD appear to overlap with disorganized and cognitive-perceptual symptoms of SPD. Symptoms of depression may aggravate self-reported features of SPQ-B, and symptoms of anxiety features of MSI. Symptoms of behavioural dysregulation of BPD and interpersonal deficits of SPQ appear to be non-overlapping. (C) 2016 Elsevier Masson SAS. All rights reserved.Peer reviewe
Self-reported psychosis-like experiences in patients with mood disorders
Background: Self-reported psychosis-like experiences (PEs) may be common in patients with mood disorders, but their clinical correlates are not well known. We investigated their prevalence and relationships with self-reported symptoms of depression, mania, anxiety, borderline (BPD) and schizotypal (SPD) personality disorders among psychiatric patients with mood disorders. Methods: The Community Assessment of Psychic Experiences (CAPE-42), Mood Disorder Questionnaire (MDQ), McLean Screening Instrument (MSI), The Beck Depressive Inventory (BDI), Overall Anxiety Severity and Impairment Scale (OASIS) and Schizotypal Personality Questionnaire-Brief form (SPQ-B) were filled in by patients with mood disorders (n = 282) from specialized care. Correlation coefficients between total scores and individual items of CAPE-42 and BDI, SPQ-B, MSI and MDQ were estimated. Hierarchical multivariate regression analysis was conducted to examine factors influencing the frequency of self-reported PE. Results: PEs are common in patients with mood disorders. The "frequency of positive symptoms" score of CAPE-42 correlated strongly with total score of SPQ-B (rho = 0.63; P <0.001) and moderately with total scores of BDI, MDQ OASIS and MSI (rho varied from 0.37 to 0.56; P <0.001). Individual items of CAPE-42 correlated moderately with specific items of BDI, MDQ SPQ-B and MSI (r(phi) varied from 0.2 to 0.5; P <0.001). Symptoms of anxiety, mania or hypomania and BPD were significant predictors of the "frequency of positive symptoms" score of CAPE-42. Conclusions: Several, state- and trait-related factors may underlie self-reported PEs among mood disorder patients. These include cognitive-perceptual distortions of SPD; distrustfulness, identity disturbance, dissociative and affective symptoms of BPD; and cognitive biases related to depressive or manic symptoms. (C) 2016 Elsevier Masson SAS. All rights reserved.Peer reviewe
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