Three dimensional imaging of short pulses

We exploit a slightly noncollinear second-harmonic cross-correlation scheme to map the 3D space-time intensity distribution of an unknown complex-shaped ultrashort optical pulse. We show the capability of the technique to reconstruct both the amplitude and the phase of the field through the coherence of the nonlinear interaction down to a resolution of 10 $\mu$m in space and 200 fs in time. This implies that the concept of second-harmonic holography can be employed down to the sub-ps time scale, and used to discuss the features of the technique in terms of the reconstructed fields.Comment: 16 pages, 6 figure

Competing symmetries and broken bonds in superconducting vortex-antivortex molecular crystals

Hall probe microscopy has been used to image vortex-antivortex molecules induced in superconducting Pb films by the stray fields from square arrays of magnetic dots. We have directly observed spontaneous vortex-antivortex pairs and studied how they interact with added free (anti)fluxons in an applied magnetic field. We observe a variety of phenomena arising from competing symmetries which either drive added antivortices to join antivortex shells around dots or stabilize the translationally symmetric antivortex lattice between the dots. Added vortices annihilate antivortex shells, leading first to a stable “nulling state” with no free fluxons and then, at high densities, to vortex shells around the dots stabilized by the asymmetric antipinning potential. Our experimental findings are in good agreement with Ginzburg-Landau calculations

Colloidal aggregation in microgravity by critical Casimir forces

By using the critical Casimir force, we study the attractive strength dependent aggregation of colloids with and without gravity by means of Near Field scattering. Significant differences were seen between microgravity and ground experiments, both in the structure of the formed fractal aggregates as well as the kinetics of growth. Ground measurements are severely affected by sedimentation resulting in reaction limited behavior. In microgravity, a purely diffusive behavior is seen reflected both in the measured fractal dimensions for the aggregates as well as the power law behavior in the rate of growth. Formed aggregates become more open as the attractive strength increases.Comment: 4 pages, 3 figure

Manifesto for a European research network into Problematic Usage of the Internet

Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.The Internet is now all-pervasive across much of the globe. While it has positive uses (e.g. prompt access to information, rapid news dissemination), many individuals develop Problematic Use of the Internet (PUI), an umbrella term incorporating a range of repetitive impairing behaviours. The Internet can act as a conduit for, and may contribute to, functionally impairing behaviours including excessive and compulsive video gaming, compulsive sexual behaviour, buying, gambling, streaming or social networks use. There is growing public and National health authority concern about the health and societal costs of PUI across the lifespan. Gaming Disorder is being considered for inclusion as a mental disorder in diagnostic classification systems, and was listed in the ICD-11 version released for consideration by Member States (http://www.who.int/classifications/icd/revision/timeline/en/). More research is needed into disorder definitions, validation of clinical tools, prevalence, clinical parameters, brain-based biology, socio-health-economic impact, and empirically validated intervention and policy approaches. Potential cultural differences in the magnitudes and natures of types and patterns of PUI need to be better understood, to inform optimal health policy and service development. To this end, the EU under Horizon 2020 has launched a new four-year European Cooperation in Science and Technology (COST) Action Programme (CA 16207), bringing together scientists and clinicians from across the fields of impulsive, compulsive, and addictive disorders, to advance networked interdisciplinary research into PUI across Europe and beyond, ultimately seeking to inform regulatory policies and clinical practice. This paper describes nine critical and achievable research priorities identified by the Network, needed in order to advance understanding of PUI, with a view towards identifying vulnerable individuals for early intervention. The network shall enable collaborative research networks, shared multinational databases, multicentre studies and joint publications.Peer reviewe

Perceived parental permissiveness toward gambling and risky behaviors in adolescents

Abstract Background and aims Perceived parental permissiveness toward gambling may relate to adolescents’ engagement in various risky behaviors. To examine this possibility, we analyzed data from a high-school based risk-behavior survey to assess relationships between perceived parental permissiveness toward gambling and adolescent gambling behavior, substance use and related problems. We also evaluated predictions that relationships between perceived parental permissiveness toward gambling and risky behaviors would be particularly strong amongst adolescents reporting high sensation-seeking or impulsivity. Methods High-school students (n = 2,805) provided data on risky behaviors, perceived parental permissiveness toward gambling, impulsivity and sensation-seeking. Bivariate and logistic regression analyses were conducted to examine relationships with gambling and alcohol, cigarette and marijuana use. Results Perceived parental permissiveness toward gambling related significantly to adolescent gambling, all substance-use behaviors as well as alcohol and drug problems. There were significant parental-permissiveness-by-sensation-seeking interactions in multiple models. Relationships between perceived parental permissiveness toward gambling and alcohol-use frequency were particularly strong among those with high sensation-seeking. This relationship also applied to gambling and heavy cigarette smoking, albeit to a lesser extent. Impulsivity related strongly to drug problems among those who perceived their parents to be more and less permissive toward gambling. Discussion and conclusions These findings support the relevance of perceived parental permissiveness toward gambling to adolescent risky behaviors. Parenting perceived as less permissive toward gambling appeared to have protective effects on gambling, alcohol and cigarette use, even among those with high sensation-seeking. Reducing parental permissiveness toward gambling may be a valuable intervention goal, particularly for parents of sensation-seeking adolescents

Comparing generalized and specific problematic smartphone/internet use: longitudinal relationships between smartphone application- based addiction and social media addiction and psychological distress

Background and aims: The literature has proposed two types of problematic smartphone/internet use: generalized problematic use and specific problematic use. However, longitudinal findings on the associations between the two types of problematic use and psychological distress are lacking among East-Asians. The present study examined temporal associations between both generalized and specific problematic use of the smartphone/internet, and psychological distress. Methods: Hong Kong University students (N 5 308; 100 males; mean age 5 23.75 years; SD ± 5.15) were recruited with follow-ups at three, six, and nine months after baseline assessment. All participants completed the Smartphone Application-Based Addiction Scale (for generalized problematic smartphone/internet use), the Bergen Social Media Addiction Scale (for specific problematic smartphone/internet use), and the Hospital Anxiety and Depression Scale (for psychological distress) in each assessment. Latent growth modeling (LGM) was constructed to understand temporal associations between generalized/specific problematic use and psychological distress. Results: The LGM suggested that the intercept of generalized problematic use was significantly associated with the intercept of psychological distress (standardized coefficient [b] 5 0.32; P < 0.01). The growth of generalized problematic use was significantly associated with the growth of psychological distress (b 5 0.51; P < 0.01). Moreover, the intercept of specific problematic use was significantly associated with the intercept of psychological distress (b 5 0.28; P < 0.01) and the growth of psychological distress (b 5 0.37; P < 0.01). Conclusion: The initial level of problematic use of the smartphone/internet may prevent psychological distress

Epigallocatechin Gallate, a Green Tea Polyphenol, Mediates NO-dependent Vasodilation Using Signaling Pathways in Vascular Endothelium Requiring Reactive Oxygen Species and Fyn

Green tea consumption is associated with reduced cardiovascular mortality in some epidemiological studies. Epigallocatechin gallate (EGCG), a bioactive polyphenol in green tea, mimics metabolic actions of insulin to inhibit gluconeogenesis in hepatocytes. Because signaling pathways regulating metabolic and vasodilator actions of insulin are shared in common, we hypothesized that EGCG may also have vasodilator actions to stimulate production of nitric oxide (NO) from endothelial cells. Acute intra-arterial administration of EGCG to mesenteric vascular beds isolated ex vivo from WKY rats caused dose-dependent vasorelaxation. This was inhibitable by L-NAME (NO synthase inhibitor), wortmannin (phosphatidylinositol 3-kinase inhibitor), or PP2 (Src family kinase inhibitor). Treatment of bovine aortic endothelial cells (BAEC) with EGCG (50 microm) acutely stimulated production of NO (assessed with NO-specific fluorescent dye DAF-2) that was inhibitable by l-NAME, wortmannin, or PP2. Stimulation of BAEC with EGCG also resulted in dose- and time-dependent phosphorylation of eNOS that was inhibitable by wortmannin or PP2 (but not by MEK inhibitor PD98059). Specific knockdown of Fyn (but not Src) with small interfering RNA inhibited both EGCG-stimulated phosphorylation of Akt and eNOS as well as production of NO in BAEC. Treatment of BAEC with EGCG generated intracellular H(2)O(2) (assessed with H(2)O(2)-specific fluorescent dye CM-H(2)DCF-DA), whereas treatment with N-acetylcysteine inhibited EGCG-stimulated phosphorylation of Fyn, Akt, and eNOS. We conclude that EGCG has endothelial-dependent vasodilator actions mediated by intracellular signaling pathways requiring reactive oxygen species and Fyn that lead to activation of phosphatidylinositol 3-kinase, Akt, and eNOS. This mechanism may explain, in part, beneficial vascular and metabolic health effects of green tea consumption

The energy dependence of flow in Ni induced collisions from 400 to 1970A MeV

We study the energy dependence of collective (hydrodynamic-like) nuclear matter flow in 400-1970 A MeV Ni+Au and 1000-1970 A MeV Ni+Cu reactions. The flow increases with energy, reaches a maximum, and then gradually decreases at higher energies. A way of comparing the energy dependence of flow values for different projectile-target mass combinations is introduced, which demonstrates a common scaling behaviour among flow values from different systems.Comment: 12 pages, 3 figures. Submitted to Physical Review Letter

An exploratory examination of marijuana use, problem-gambling severity, and health correlates among adolescents

Abstract Background and aims Gambling is common in adolescents and at-risk and problem/pathological gambling (ARPG) is associated with adverse measures of health and functioning in this population. Although ARPG commonly co-occurs with marijuana use, little is known how marijuana use influences the relationship between problem-gambling severity and health- and gambling-related measures. Methods Survey data from 2,252 Connecticut high school students were analyzed using chi-square and logistic regression analyses. Results ARPG was found more frequently in adolescents with lifetime marijuana use than in adolescents denying marijuana use. Marijuana use was associated with more severe and a higher frequency of gambling-related behaviors and different motivations for gambling. Multiple health/functioning impairments were differentially associated with problem-gambling severity amongst adolescents with and without marijuana use. Significant marijuana-use-by-problem-gambling-severity-group interactions were observed for low-average grades (OR = 0.39, 95% CI = [0.20, 0.77]), cigarette smoking (OR = 0.38, 95% CI = [0.17, 0.83]), current alcohol use (OR = 0.36, 95% CI = [0.14, 0.91]), and gambling with friends (OR = 0.47, 95% CI = [0.28, 0.77]). In all cases, weaker associations between problem-gambling severity and health/functioning correlates were observed in the marijuana-use group as compared to the marijuana-non-use group. Conclusions Some academic, substance use, and social factors related to problem-gambling severity may be partially accounted for by a relationship with marijuana use. Identifying specific factors that underlie the relationships between specific attitudes and behaviors with gambling problems and marijuana use may help improve intervention strategies