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This study used canonical correlation analysis to investigate patterns of shared variance between parameters measured in seven different occulomotor function tasks, namely the visually guided saccade task, the antisaccade task, the closed-loop smooth-pursuit task, the open-loop smooth-pursuit task, and three active visual fixation tasks. These tasks were performed by 2130 young army recruits. Only a small percentage (1-10%) of shared variance existed between sets of parameters for all oculomotor function tasks measured. The most correlated tasks were the visually guided saccade and the antisaccade. The first common factor correlated with speed of performance between these tasks (latency), while the second and third correlated with accuracy of performance. Better performance in active visual fixation tasks correlated with better performance accuracy (lower error rate) and increased speed (lower latency) in the antisaccade and saccade tasks as well as better performance in the closed-loop smooth-pursuit task (increase in gain and decrease in the rate of unwanted saccades during pursuit). Better performance in the closed-loop smooth-pursuit task (increased gain and decreased number of unwanted saccades) also correlated with increased accuracy and increased speed of performing saccades and antisaccades. Finally, the open-loop fixation task had no correlation with all other oculomotor tasks except for a very weak negative correlation with the closed-loop pursuit task where better performance (increased gain) in one correlated with worse performance (decreased gain) in the other. The results of this analysis showed that a small percentage of variance is shared among different oculomotor function tasks. The structure of this shared variance could be used to derive common oculomotor function indices to study their relation to genetic and other sources of inter-subject variation. [ABSTRACT FROM AUTHOR]

Since the seminal study of Steinbeck and Durell (1968), few epidemiological studies have attempted to replicate whether psychosocial stress precipitates the onset of a first psychotic episode. Our aim was to support or refute the finding of elevated psychosis incidence in the first month of army induction and to examine factors impacting the timing of onset. Data were collected from medical files of 186 army conscripts, hospitalized with a diagnosis of First Episode Psychosis (FEP) between 2005 and 2014 in the Psychiatric Military Hospital in Athens, Greece. FEP rates were at least 4.5 times higher in the first month of military service, compared with any other month. Earlier FEP onset was associated with rural environment at the time of birth, multiple drug use and service away from home. Psychosocial stress precipitates FEP, particularly in those exposed to other risk factors. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to systematically appraise the meta‐analyses of observational studies on risk factors and peripheral biomarkers for schizophrenia spectrum disorders. Methods: We conducted an umbrella review to capture all meta‐analyses and Mendelian randomization studies that examined associations between non‐genetic risk factors and schizophrenia spectrum disorders. For each eligible meta‐analysis, we estimated the summary effect size estimate, its 95% confidence and prediction intervals and the I2 metric. Additionally, evidence for small‐study effects and excess significance bias was assessed. Results: Overall, we found 41 eligible papers including 98 associations. Sixty‐two associations had a nominally significant (P‐value <0.05) effect. Seventy‐two of the associations exhibited large or very large between‐study heterogeneity, while 13 associations had evidence for small‐study effects. Excess significance bias was found in 18 associations. Only five factors (childhood adversities, cannabis use, history of obstetric complications, stressful events during adulthood, and serum folate level) showed robust evidence. Conclusion: Despite identifying 98 associations, there is only robust evidence to suggest that cannabis use, exposure to stressful events during childhood and adulthood, history of obstetric complications, and low serum folate level confer a higher risk for developing schizophrenia spectrum disorders. The evidence on peripheral biomarkers for schizophrenia spectrum disorders remains limited. [ABSTRACT FROM AUTHOR]

We attempt to identify a path layout in the definition of transverse-momentum-dependent T-odd parton distribution functions (TMD)s which combines features of both, initial- and final-state interactions, so that it remains universal despite the fact that the Wilson lines entering such TMDs change their orientation. The generic structure of the quark correlator for this path layout is calculated. [ABSTRACT FROM AUTHOR]

We provide an in-depth analysis of the π distribution amplitude in terms of two different Gegenbauer representations. Detailed predictions for the $${\pi-\gamma}$$ transition form factor are presented, obtained with light-cone sum rules. Various π distribution amplitudes are tested and the crucial role of their endpoint behavior in the form-factor analysis is discussed. Comparison with the data is given. [ABSTRACT FROM AUTHOR]

Detailed predictions for the scaled pion-photon transition form factor are given, derived with the method of light-cone sum rules and using pion distribution amplitudes with two and three Gegenbauer coefficients obtained from QCD sum rules with nonlocal condensates. These predictions agree well with all experimental data that are compatible with QCD scaling (and collinear factorization), but disagree with the high- Q data of the BaBar Collaboration that grow with the momentum. A good agreement of our predictions with results obtained from AdS/QCD models and Dyson-Schwinger computations is found. [ABSTRACT FROM AUTHOR]

The leading-twist distribution amplitude for the longitudinal rho-meson was studied using QCD Sum Rules with nonlocal condensates and a spectral density which includes next-to-leading order radiative corrections. The obtained profile is compared with results from standard QCD sum rules, lattice QCD, holographic QCD, a light-front quark model, and the instanton liquid model. Preliminary estimates for the first two moments of the transverse ρ-meson distribution amplitude are also given. [ABSTRACT FROM AUTHOR]

We show that the geometry of the Wilson lines, entering the operator definition of the transverse-momentum dependent parton distributions and that of the soft factor, follows from the kinematics of the underlying physical process in conjunction with the gauge invariance of the QCD Lagrangian. We demonstrate our method in terms of concrete examples and determine the paths of the associated Wilson lines. The validation of the factorization theorem in our approach is postponed to future work. [ABSTRACT FROM AUTHOR]

An analysis of all available data (CELLO, CLEO, B A B AR) in the range [1÷ 40] GeV for the pion-photon transition form factor in terms of light-cone sum rules with next-to-leading-order accuracy is discussed, including twist-four contributions and next-to-next-to-leading order and twist-six corrections-the latter two via uncertainties. The antithetic trend between the B A B AR data for the γ*γ π and those for the γ* γ η( η′) transition is pointed out, emphasizing the underlying antagonistic mechanisms: endpoint enhancement for the first and endpoint-suppression for the second-each associated with pseudoscalar meson distribution amplitudes with distinct endpoint characteristics. [ABSTRACT FROM AUTHOR]

BackgroundThe gene encoding the regulator of G-protein signaling subtype 4 (RGS4), located on chromosome 1q23-3, has been proposed as a possible susceptibility gene for schizophrenia and has been specifically linked to prefrontal cortical structural and functional integrity.MethodThe effects of four core single nucleotide polymorphisms (SNPs) within the RGS4 gene on oculomotor parameters in a battery of oculomotor tasks (saccade, antisaccade, smooth eye pursuit, fixation) were investigated in a sample of 2243 young male military conscripts.ResultsThe risk allele of RGS4SNP18 was found to be associated with two variables of antisaccade performance, increased error rate and variation in the correct antisaccade latency. By contrast, the same allele and also the risk allele of RGS4SNP4 led to an improvement in smooth eye pursuit performance (increased gain). Structural equation modeling confirmed that the combined gene variation of RGS4SNP4 and RGS4SNP18 was a significant predictor of antisaccade but not smooth eye pursuit performance.ConclusionsThese results provide evidence for a specific effect of schizophrenia-related RGS4 genotype variations to prefrontal dysfunction measured by oculomotor indices of performance in normal individuals, further validating the hypothesis that RGS4 is related to prefrontal dysfunction in schizophrenia. [ABSTRACT FROM PUBLISHER]

We discuss the possibility of quantum entanglement for pairs of charged particles produced in high-energy pp-collisions at the LHC. Using a framework of interacting Wilson lines, we calculate 2D and 1D two-particle angular correlation functions in terms of the differences of the pseudorapidities and azimuthal angles of the produced particles. The calculated near-side angular correlation shows a localized maximum around Δϕ≈0, though it is less pronounced compared to the peak observed by the CMS Collaboration. We argue that this soft correlation is universal and insensitive to the specific properties of the matter (quark-gluon plasma, QCD vacuum, etc.) used to describe hadronic states - though such properties can be included to further improve the results. [ABSTRACT FROM AUTHOR]

BackgroundThere may be biological plausibility to the notion that cannabis use and childhood trauma or maltreatment synergistically increase the risk for later development of psychotic symptoms. To replicate and further investigate this issue, prospective data from two independent population-based studies, the Greek National Perinatal Study (n=1636) and The Netherlands Mental Health Survey and Incidence Study (NEMESIS) (n=4842), were analyzed.MethodTwo different data sets on cannabis use and childhood maltreatment were used. In a large Greek population-based cohort study, data on cannabis use at age 19 years and childhood maltreatment at 7 years were assessed. In addition, psychotic symptoms were assessed using the Community Assessment of Psychic Experiences (CAPE). In NEMESIS, the Composite International Diagnostic Interview (CIDI) was used to assess psychotic symptoms at three different time points along with childhood maltreatment and lifetime cannabis use.ResultsA significant adjusted interaction between childhood maltreatment and later cannabis use was evident in both samples, indicating that the psychosis-inducing effects of cannabis were stronger in individuals exposed to earlier sexual or physical mistreatment [Greek National Perinatal Study: test for interaction F(2, 1627)=4.18, p=0.02; NEMESIS: test for interaction χ2(3)=8.08, p=0.04].ConclusionsCross-sensitivity between childhood maltreatment and cannabis use may exist in pathways that shape the risk for expression of positive psychotic symptoms. [ABSTRACT FROM PUBLISHER]

Introduction. Although there is some evidence that Theory of Mind (ToM) deficits may be trait markers of schizophrenia it is not clear yet if ToM deficits are primary deficits, that is, to be independent of deficits in general intellectual abilities and executive function. The aim was to examine if ToM deficits may be trait markers of the illness and the effect of cognitive inhibition, general intellectual abilities and depression on ToM abilities of patients with schizophrenia and their unaffected parents. Methods. We assessed ToM abilities (first-order and second-order ToM stories, The Revised Eyes Test), cognitive inhibition (Stroop Task), general intellectual ability (Standard Progressive Matrices Test Plus) in patients with schizophrenia (N=21) and their unaffected fathers (N=21) and mothers (N=21) in comparison with healthy control families (healthy control males, N=21, healthy control fathers, N=21, healthy control mothers, N=21) Results. Patients showed deficits in first-order ToM tasks but some of these deficits were mediated by general intellectual abilities. Impairments in cognitive inhibition mediated only patients’ performance in The Revised Eyes Test. Patients showed deficits in second-order ToM stories independently of deficits in general intellectual abilities and cognitive inhibition. Unaffected parents did not show deficits in first-order ToM tasks, whereas they showed deficits in second-order ToM stories. However, the deficits that unaffected parents showed in second-order ToM stories were mediated by their deficits in general intellectual abilities, and there was an effect of remitted depression on the unaffected mothers’ performance. Conclusions. The results suggest that intact neurocognitive and general intellectual abilities are necessary in order patients and their unaffected parents to pass successfully ToM tasks. Patients and their unaffected parents show ToM deficits but these deficits are not similar. Patients show ToM deficits but these deficits seem to be a component of the pathophysiology of the illness (e.g., deficits in executive function, general intellectual abilities). [ABSTRACT FROM PUBLISHER]

Background/Aims: The brain-derived neurotrophic factor (BDNF) levels in serum and the central nervous system are altered in patients with schizophrenia, suggesting that changes in the expression of BDNF might contribute to the disease pathophysiology. Long duration of untreated psychosis (DUP) has been associated with poorer prognosis in patients with schizophrenia. Such a relationship of untreated psychosis to outcome may indicate a neurodegenerative process and may have important implications for understanding the pathophysiology of schizophrenia. Methods: In this study, we investigated the association between serum BDNF levels and DUP in a sample of drug-naïve patients in their first episode of schizophrenia (FEP). We investigated serum BDNF levels in a sample of 37 drug-naïve FEP patients and 21 matched healthy subjects. Results: The serum BDNF level in the sample of FEP was significantly reduced compared to the healthy subjects (18.87 ± 8.23 vs. 29.2 ± 7.73 ng/ml, t = 4.76, d.f. = 57, p = 0.01). A negative correlation was found between serum BDNF levels and DUP in the group of patients (r = –0.346, p = 0.036). Conclusions: Our findings indicate that low serum BDNF levels at the onset of schizophrenia were associated with a long DUP and this could reflect an acute neurodegenerative reaction during the untreated phase of psychosis. Copyright © 2010 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

We present results of a calculation of the electromagnetic pion form factor within the framework of QCD sum rules with nonlocal condensates and using a perturbative spectral density which includes O( α s) contributions. [ABSTRACT FROM AUTHOR]

We discuss the QCD sum-rule approach for the spacelike electromagnetic pion form factor in the O(αs) approximation. We show that the nonlocality of the condensates is a key point to include nonperturbative contributions to the pion form factor. We compare our results with the Local-Duality predictions and show that the continuum threshold s0(Q2) parameter is highly underestimated in the Local-Duality approach at Q2 ≳ 2 GeV2. Using our fit for this parameter, $s_0^{{\rm{LD}}} (Q^2 )$ and applying the fractional analytic perturbation theory, we estimate with an accuracy of the order of 1% the $O(\alpha _s^2 )$ contribution to the pion's form factor. [ABSTRACT FROM AUTHOR]

We use light-cone QCD sum rules to calculate the pion-photon transition form factor, taking into account radiative corrections up to the next-to-next-to-leading order of perturbation theory. We compare the obtained predictions with all available experimental data from the CELLO, CLEO, and the BaBar Collaborations. We point out that the BaBar data are incompatible with the convolution scheme of QCD, on which our predictions are based, and can possibly be explained only with a violation of the factorization theorem. We pull together recent theoretical results and comment on their significance. [ABSTRACT FROM AUTHOR]

The ultraviolet and rapidity divergences of transverse-momentum dependent parton distribution functions with lightlike and transverse gauge links is studied, also incorporating a soft eikonal factor. We find that in the light-cone gauge with q--independent pole prescriptions extra divergences appear which amount, at one-loop, to a cusp-like anomalous-dimension. We show that such contributions are absent when the Mandelstam-Leibbrandt prescription is used. In the first case, the soft factor cancels the anomalous dimension defect, while in the second case its ultraviolet-divergent part reduces to unity. [ABSTRACT FROM AUTHOR]

We study the phenomenon of duality in hard exclusive reactions to which QCD factorization applies. Considering “two-photon”-like processes in the scalar φ model and also two-hadron (pion) production from the collisions of a real (transversely polarized) and a highly-virtual, longitudinally polarized photon in QCD, we identify two regimes of factorization, each of them associated with a distinct nonperturbative mechanism. One mechanism involves twist-3 Generalized Distribution Amplitudes, whereas the other one employs leading-twist Transition Distribution Amplitudes. In the case of the scalar φ model, we find duality in that kinematical region where the two mechanisms overlap. In the QCD case, the appearance of duality is sensitive to the particular nonperturbative model applied and can, therefore, be used as an additional adjudicator. [ABSTRACT FROM AUTHOR]

Background This article presents a study of the Occupational Abilities and Performance Scale (OAPS), developed for administration to schizophrenic patients. The reliability and validity of the OAPS has been evaluated. Method A total of 174 schizophrenic patients who participated in the Psychosocial and Vocational Rehabilitation Unit (PVRU) of the University Mental Health Research Institute (UMHRI) in Athens were assessed. The OAPS is conducted at entry and after 18 months, when the client has completed training. Results The results of the reliability analysis showed very good internal consistency, with high split-half reliability as well as test-retest reliability and inter-rater agreement. The scale was also found to have good predictive validity, as well as concurrent validity. Finally, factor analysis with principal components extraction method was performed in order to assess the construct validity of the scale. Conclusions The results of factor analysis supported the conclusion of good reliability and validity of the OAPS and revealed the existence of five components, each correlated with a set of the original items. [ABSTRACT FROM AUTHOR]

To investigate the effect of exposure to cannabis early in adolescence on subclinical positive and negative symptoms of psychosis.Cross-sectional survey in the context of an ongoing cohort study.Government-supported general population cohort study.A total of 3500 representative 19-year olds in Greece.Subjects filled in the 40-item Community Assessment of Psychic Experiences, measuring subclinical positive (paranoia, hallucinations, grandiosity, first-rank symptoms) and negative psychosis dimensions and depression. Drug use was also reported on.Use of cannabis was associated positively with both positive and negative dimensions of psychosis, independent of each other, and of depression. An association between cannabis and depression disappeared after adjustment for the negative psychosis dimensions. First use of cannabis below age 16 years was associated with a much stronger effect than first use after age 15 years, independent of life-time frequency of use. The association between cannabis and psychosis was not influenced by the distress associated with the experiences, indicating that self-medication may be an unlikely explanation for the entire association between cannabis and psychosis.These results add credence to the hypothesis that cannabis contributes to the population level of expression of psychosis. In particular, exposure early in adolescence may increase the risk for the subclinical positive and negative dimensions of psychosis, but not for depression. [ABSTRACT FROM AUTHOR]

Rates of psychotic disorder and related attenuated psychotic experiences are higher in urban areas. We examined to what degree differences between urban and rural areas could be attributed to differences in cognitive development. Young men from urban areas had higher scores on the SPQ subscale Odd beliefs/magical thinking (OR=1.99, 95% CI: 1.42, 2.78), but lower scores on Excessive social anxiety (OR=0.63, 95% CI: 0.49, 0.81) and No close friends (OR=0.42, 95% CI: 0.29, 0.62). Adjustment for demographic factors, IQ and specific neuropsychological functions did not change the results. When the lower scores on Excessive social anxiety and No close friends were taken into account, the differences on the Odd beliefs/magical thinking subscale became even more pronounced (OR=2.33, 95% CI: 1.56, 3.49). Young men from urban areas are socially more competent, but display higher levels of positive psychotic experiences, which are not mediated by lower IQ or higher levels of neuropsychological impairment. [ABSTRACT FROM AUTHOR]

A total of 940 young men performed a task in which they actively maintained fixation for 50 s in three conditions: a) on a visual target, b) on a visual target while distracting targets appeared briefly on the periphery and c) with no visual target present. The same individuals completed psychometric evaluation tests measuring IQ, schizotypy and current state-dependent psychopathology. The proportion of fixation time decreased and saccade frequency increased in condition b compared wih condition a, and sequentially in condition c compared with condition b. A trend towards a decrease in proportion of fixation time and increase in saccade frequency was found as the subjects maintained fixation during the task and this time-dependent deterioration of performance was again most pronounced in condition c, less so in condition b and absent in condition a. Psychometric test scores were significantly correlated with fixation performance in the population. Worse performance in all three fixation conditions was observed for individuals with lower IQ scores. A deterioration of fixation performance with time in condition b was correlated with disorganization characteristics of schizotypy, suggesting that these individuals had difficulty maintaining active fixation in the presence of increased inhibitory load. A connection of such a difficulty with the frontal lobes and their role in the control of voluntary inhibitory functions is discussed. [ABSTRACT FROM AUTHOR]

Employing the standard hard-scattering approach (HSA) in conjunction with the running coupling (RC) method, the latter joined with the infrared renormalon calculus, we compute power-suppressed corrections ∼1/Q2n ,n=1, 2,… to the massless η′-meson-virtual-gluon transition form factor (FF) Q 2Fη′g*g8 (Q2, w). Contributions to the form factor from the quark and gluon components of the if meson are taken into account. Analytic expressions for the FFs Fη′99*(Q2>,w =±1) and Fη′g*g*(Q2,w= 0) are also presented, as well as Borel transforms B[Q2Fη′g*g*](u) and resummed expressions. It is shown that except for w =±1, 0, the Borel transform contains an infinite number of infrared renormalon poles. It is demonstrated that in the explored range of the total gluon virtuality 1 GeV2 2 < 25 GeV2, power corrections found with the RC method considerably enhance the FF η′g*g* (Q2, w) relative to results obtained only in the context of the standard HSA with a "frozen" coupling. [ABSTRACT FROM AUTHOR]

A sample of 676 healthy young males performed visually guided saccades and antisaccades and completed the Porac-Coren questionnaire measuring lateral preferences. There was no difference in mean latency between rightward versus leftward saccades or for saccades executed in the left versus right hemispace. There was also no right/left asymmetry for individuals with left or right dominance as assessed by the lateral preferences questionnaire. The same results were observed for the latency of antisaccades and for the error rate in the antisaccade task. Finally, we did not confirm any substantial subpopulation of individuals with idiosyncratic left/right latency asymmetries that persisted both in the saccade and antisaccade task. These results suggest that neither latency nor antisaccade error rate are good indicators of lateral preferences in these tasks. Other oculomotor tasks might be more sensitive to hemifield differences, or cerebral hemispheric asymmetry is not present at the level of cortical organization of saccades and antisaccades. [ABSTRACT FROM AUTHOR]

The modern formulation of exclusive reactions within Quantum Chromodynamics is reviewed, the emphasis being placed on the pivotal ideas and methods pertaining to perturbative and non-perturbative topics. Specific problems, related to scale locality, infrared safety, gluonic radiative corrections (Sudakov effects), and the role of hadronic size effects (intrinsic transverse momentum), are studied. These issues are more precisely analyzed in terms of the essential mechanisms of momentum transfer to a hadron while remaining intact. Different factorization schemes are considered and the conceptual lacunas are pointed out. The quite technical subject of renormalization-group evolution is given a detailed account. By combining analytical and numerical algorithms, the one-gluon exchange nucleon evolution equation is diagonalized and next-to-leading eigenfunctions are calculated in terms of Appell polynomials. The corresponding anomalous dimensions of trilinear quark operators are found to form a degenerate system whose envelope shows logarithmic large-order behavior. Selected applications of this framework are presented, focusing on the helicity-conserving elastic form factors of the pion and the nucleon. The theoretical constraints imposed by QCD sum rules on the moments of nucleon distribution amplitudes are used to determine a whole spectrum of optional solutions. They organize themselves along an “orbit” characterized by a striking scaling relation between the form-factor ratio $$R= \vert G_{\rm n}^{\rm M}\vert/G_{\rm M}^{\rm p}$$ and the projection coefficient B4 on to the corresponding eigensolution. The main reasons for the failure of the present theoretical predictions to match the experimental data are discussed and workable explanations are sketched. [ABSTRACT FROM AUTHOR]

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The behavior of the proton magnetic form factor is studied within the modified hard scattering picture, which takes into account gluonic radiative corrections in terms of transverse separations. We parallel the analysis given previously by Li and make apparent a serious objection. The appropriate cut-off needed to render the form-factor calculation finite is both detailed and analyzed by considering different cut-off prescriptions. The use of the maximum interquark separation as a common infrared cut-off in the Sudakov suppression factor is proposed, since it avoids difficulties with the α-singularrities and yields a proton form factor insensitive to the inclusion of the soft region which therefore can be confidently attributed to perturbative QCD. Results are presented for a variety of proton wave functions including also their intrinsic transverse momentum. It turns out that the perturbative contribution, although theoretically self-consistent for Q larger than about 6 GeV to 10 GeV, is too small compared to the data. [ABSTRACT FROM AUTHOR]