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Obesity is a chronic disease, in which treatment outcomes are highly dependent on patient and family adherence to behavioural recommendations. The role of healthy eating, physical activity, medication adherence as well as adherence to pre- and post-bariatric surgery protocols are of utmost importance for long-term treatment outcomes. Even the best interventions are not likely to reach their maximum benefit without significant levels of adherence on the part of the individual and family. Traditionally, the annual meeting of the European Childhood Obesity Group (ECOG) includes an expert workshop addressing one specific topic within the field of childhood obesity. During the 30th annual meeting, hosted by the University of Pécs, Hungary, as a virtual meeting, “adherence to treatment recommendations in obesity as a chronic disease” was addressed. The discussions that developed during the workshop are summarized in the following article.

To develop and validate an easy-to-use screening tool for identifying adolescents at high-risk for insulin resistance (IR).Α total of 1,053 adolescents (554 females), aged 12.5 to 17.5 years with complete data on glucose and insulin levels were included. Body mass index (BMI), fat mass index (FMI) and the homeostasis model assessment for insulin resistance (HOMA-IR) were calculated. VOBMI and VOPaediatricians or physical education teachers can use easy-to-obtain and non-invasive measures to apply the HELENA-IR score and identify adolescents at high risk for IR, who should be referred for further tests.

Prader–Willi syndrome (PWS) is a complex genetic disorder which involves the endocrine and neurologic systems, metabolism, and behavior. The aim of this paper is to summarize current knowledge on dietary management and treatment of PWS and, in particular, to prevent excessive weight gain. Growth hormone (GH) therapy is the recommended standard treatment for PWS children, because it improves body composition (by changing the proportion of body fat and lean body mass specifically by increasing muscle mass and energy expenditure), linear growth, and in infants, it promotes psychomotor and IQ development. In early childhood, the predominant symptom is hyperphagia which can lead to early onset, severe obesity with different obesity-related comorbidities. There are several studies on anti-obesity medications (metformin, topiramate, liraglutide, setmelanotide). However, these are still limited, and no widely accepted consensus guideline exists concerning these drugs in children with PWS. Until there is a specific treatment for hyperphagia and weight gain, weight must be controlled with the help of diet and exercise. Below the age of one year, children with PWS have no desire to eat and will often fail to thrive, despite adequate calories. After the age of two years, weight begins to increase without a change in calorie intake. Appetite increases later, gradually, and becomes insatiable. Managing the progression of different nutritional phases (0–4) is really important and can delay the early onset of severe obesity. Multidisciplinary approaches are crucial in the diagnosis and lifelong follow-up, which will determine the quality of life of these patients.

[Objectives] To develop and validate an easy-to-use screening tool for identifying adolescents at high-risk for insulin resistance (IR)., [Methods] Α total of 1,053 adolescents (554 females), aged 12.5 to 17.5 years with complete data on glucose and insulin levels were included. Body mass index (BMI), fat mass index (FMI) and the homeostasis model assessment for insulin resistance (HOMA-IR) were calculated. VO2max was predicted using 20 m multi-stage fitness test. The population was randomly separated into two cohorts for the development (n=702) and validation (n=351) of the index, respectively. Factors associated with high HOMA-IR were identified by Spearman correlation in the development cohort; multiple logistic regression was performed for all identified independent factors to develop a score index. Finally, receiver operating characteristic (ROC) analysis was performed in the validation cohort and was used to define the cut-off values that could identify adolescents above the 75th and the 95th percentile for HOMA-IR., [Results] BMI and VO2max significantly identified high HOMA-IR in males; and FMI, TV watching and VO2max in females. The HELENA-IR index scores range from 0 to 29 for males and 0 to 43 for females. The Area Under the Curve, sensitivity and specificity for identifying males above the 75th and 95th of HOMA-IR percentiles were 0.635 (95%CI: 0.542–0.725), 0.513 and 0.735, and 0.714 (95%CI: 0.499–0.728), 0.625 and 0.905, respectively. For females, the corresponding values were 0.632 (95%CI: 0.538–0.725), 0.568 and 0.652, and 0.708 (95%CI: 0.559–0.725), 0.667 and 0.617, respectively. Simple algorithms were created using the index cut-off scores., [Conclusions] Paediatricians or physical education teachers can use easy-to-obtain and non-invasive measures to apply the HELENA-IR score and identify adolescents at high risk for IR, who should be referred for further tests., The HELENA study was financially supported by the European Community Sixth RTD Framework Programme (Contract FOOD-CT-2005-007034).

Comparison of hydrodynamic calculations with experimental data inevitably requires a model for converting the fluid to particles. For shear viscous fluids, several different conversion models have been proposed, such as the quadratic Grad corrections, the Strickland-Romatschke (SR) ansatz, self-consistent shear corrections from linearized kinetic theory, or corrections from the relaxation time approach. We show, via comparison to nonlinear $2\ensuremath{\rightarrow}2$ kinetic theory evolution, that even for low specific shear viscosities $0.03\ensuremath{\lesssim}\ensuremath{\eta}/s\ensuremath{\lesssim}0.2$, these four models have varying accuracy and still significant errors in reproducing particle phase space densities from hydrodynamic fields. Moreover, we demonstrate that the overall reconstruction error of additive shear viscous $f={f}_{\mathrm{eq}}+\ensuremath{\delta}f$ models dramatically reduces by up to one order of magnitude, if one ensures through exponentiation that $f$ is always positive. We also illustrate how even more accurate viscous $\ensuremath{\delta}f$ models can be constructed by incorporating the first time derivatives of hydrodynamic fields to account for the past evolution of the system. Such time derivatives are readily available in hydrodynamic simulations, though usually not included in the output. Though our comparisons are limited to a one-component massless system undergoing a $(0+1)$-dimensional $(0+1\mathrm{D})$ longitudinal boost-invariant expansion, we expect that the improved models will be useful in $2+1\mathrm{D}$ and $3+1\mathrm{D}$ hydrodynamic studies as well.

Recently NAano-Plasmonic, Laser Inertial Fusion Experiments (NAPLIFE) were proposed, as an improved way to achieve laser driven fusion. The improvement is the combination of two basic research discoveries: (i) The possibility of detonations on space-time hyper-surfaces with time-like normal (i.e. simultaneous detonation in a whole volume) and (ii) to increase this volume to the whole target, by regulating the laser light absorption using nano-shells or nano-rods as antennas. These principles can be realized in an in-line, one dimensional configuration, in the simplest way with two opposing laser beams as in particle colliders. Such, opposing laser beam experiments were also performed recently. Here we study the consequences of the Laser Wake Field Acceleration (LWFA) if we experience it in a colliding laser beam set up. These studies can be applied to laser driven fusion, but also to other rapid phase transition, combustion, or ignition studies in other materials., Comment: 7 pages, 5 figures. arXiv admin note: text overlap with arXiv:2008.09847

It is commonly believed that azimuthal anisotropies in relativistic heavy ion collisions are generated by hydrodynamic evolution of the strongly interacting quark-gluon plasma. Here we use transport models to study how azimuthal anisotropies depend on the number of collisions that each parton suffers. We find that the majority of $v_2$ comes from the anisotropic escape of partons, not from the parton collective flow, for semi-central Au+Au collisions at 200A GeV. As expected, the fraction of $v_2$ from the anisotropic particle escape is even higher for smaller systems such as d+Au. Our transport model results also confirm that azimuthal anisotropies would be dominated by hydrodynamic flow at unrealistically-high parton cross sections. Our finding thus naturally explains the similarity of azimuthal anisotropies in small and large systems; however, it presents a challenge to the paradigm of anisotropic flow., 4 pages, 5 figures, Quark Matter 2015 proceedings

The quantitative extraction of quark-gluon plasma (QGP) properties from heavy-ion data, such as its specific shear viscosity $\eta /s$, typically requires comparison to viscous hydrodynamic or "hybrid" hydrodynamics+transport simulations. In either case, one has to convert the fluid to hadrons, yet without additional theory input the conversion is ambiguous for dissipative fluids. Here, shear viscous phase-space corrections calculated using linearized transport theory are applied in Cooper-Frye freezeout to quantify the effects on anisotropic flow coefficients $v_n(p_T)$ at both RHIC and LHC energies. Expanding upon our previous flow harmonics studies [1,2], we calculate pion and proton $v_2(p_T)$, $v_4(p_T)$, and $v_6(p_T)$. Unlike in Ref. [1], we incorporate a hadron gas that is chemically frozen below a temperature of 175 MeV, and use hypersurfaces from realistic viscous hydrodynamic simulations. With additive quark model cross sections and relative phase-space corrections with $p^{3/2}$ momentum dependence, rather than the quadratic Grad form, we find at moderately high transverse momentum noticeably higher $v_4(p_T)$ and $v_6(p_T)$ for protons than for pions. In addition, the value of $\eta /s$ deduced from elliptic flow data differs by nearly 50\% from the value extracted using the naive "democratic Grad" form of freeze-out distributions. To facilitate the use of the self-consistent viscous corrections calculated here in hydrodynamic and hybrid calculations, we also present convenient parameterizations of the corrections for the various hadron species (cf. Table I)., Comment: Added Figure 4, subsection III E, 4 References [29-32], and one footnote [34]. Also added an outline of the paper at the end of the introduction, some discussion of Eq. (1), and fixed the redundant alpha notation in Sec III D to kappa. 12 pages, 11 Figures, 1 Table

Both hydrodynamics-based models and a multi-phase transport (AMPT) model can reproduce the mass splitting of azimuthal anisotropy ($v_n$) at low transverse momentum ($p_{\perp}$) as observed in heavy ion collisions. In the AMPT model, however, $v_n$ is mainly generated by the parton escape mechanism, not by the hydrodynamic flow. In this study we provide detailed results on the mass splitting of $v_n$ in this transport model, including $v_2$ and $v_3$ of various hadron species in d+Au and Au+Au collisions at the Relativistic Heavy Ion Collider and p+Pb collisions at the Large Hadron Collider. We show that the mass splitting of hadron $v_2$ and $v_3$ in AMPT first arises from the kinematics in the quark coalescence hadronization process, and then, more dominantly, comes from hadronic rescatterings, even though the contribution from the latter to the overall charged hadron $v_n$ is small. We further show that there is no qualitative difference between heavy ion collisions and small-system collisions or between elliptic ($v_2$) and triangular ($v_3$) anisotropies. Our studies thus demonstrate that the mass splitting of $v_2$ and $v_3$ at low-$p_{\perp}$ is not a unique signature of hydrodynamic collective flow but can be the interplay of several physics effects., Comment: 11 pages, 12 figures. Followup long paper to H. Li et al. Phys. Rev. C 93 (2016) 051901(R) (2016) [arXiv:1601.05390]; changes from v1 to v2: added phi-meson results in Fig.2 and Fig.11; v3: published version

The Healthy Dietary Adherence Score (HDAS). (DOCX 24Â kb)

We study the consistency between high-pT nuclear suppression (R_AA) and elliptic flow (v2) using Gyulassy-Levai-Vitev (GLV) energy loss or a simpler power-law dE/dL formula, for a variety of bulk evolution models. The results generally confirm our earlier work [arXiv:1305.1046] that found suppressed elliptic flow for transversely expanding media. One exception is the set of hydrodynamic solutions used recently [arXiv:1305.6458] by Betz and Gyulassy, which give significantly higher v2 but unfortunately assume unrealistic bag-model equation of state. On the other hand, we show that covariant treatment of energy loss introduces an interplay between jet direction and hydrodynamic flow of the medium, which largely counteracts elliptic flow suppression caused by transverse expansion., Comment: Presentation at Hard Probes 2013 (4 pages, 8 PDF plots, Elsevier style file)

We present results from a jet energy loss calculation using the Gyulassy-Levai-Vitev (GLV) formalism and bulk medium evolution from the covariant transport model MPC. At both RHIC and LHC energies we find that realistic transverse expansion strongly reduces elliptic flow at high pT compared to calculations with transversely 'frozen' profiles. We argue that this is a generic feature of GLV energy loss. Transverse expansion also leads to stronger high-pT suppression, while fluctuations in energy loss with the location of scattering centers weaken the suppression. But, unlike the reduction of v2, these effects nearly disappear once alpha_s is adjusted to reproduce R_AA in central collisions., Contribution to Hard Probes 2012 Int. Conf. (4 pages, 8 PDF figures, Elsevier pdflatex style file)

On behalf of the HELENA study group., [Background]: Previous research has shown that diet is associated with low-grade systemic inflammation among adults. However, no study has yet been conducted to explore the association between inflammatory potential of diet and low-grade systemic inflammation among adolescents whose dietary behavior may be different from adults. [Methods and Results]: We examine the predictive ability of 24-h recall-derived dietary inflammatory index (DII) scores on inflammation among 532 European adolescents in the HELENA cross-sectional study. The DII is a literature-derived dietary index developed to predict inflammation. The DII was calculated per 1000 calories and was tested against C-reactive protein, ILs-1,2,4,10, TNF-α, ICAM, vascular cell adhesion molecule (VCAM), and IFN-γ. All inflammatory markers had nonnormal distributions and therefore were log transformed. Analyses were performed using multivariable linear regression, adjusting for age, sex, city, BMI, smoking, and physical activity. Pro-inflammatory diet (higher DII scores) was associated with increased levels of various inflammatory markers: TNF-α, IL-1, 2, IFN-γ, and vascular cell adhesion molecule (b = 0.13, 95% CI: 0.001, 0.25; 0.13, 95% CI 0.001, 0.25; 0.40, 95% CI: 0.03, 0.77; 0.53, 95% CI: 0.05, 1.01; 0.07, 95% CI: 0.01, 0.13, respectively). [Conclusion]: These results reinforce the fact that diet, as a whole, plays an important role in modifying inflammation in adolescents., This work was performed as part of the HELENA study. We gratefully acknowledge the financial support of the European Community sixth RTD Framework Programme (contact FOOD-CT-2005-007034). Drs. N.S. and J.R.H. were supported by the United States National Institute for Diabetes, Digestive and Kidney Diseases (grant no. R44DK103377).

The mass splitting of elliptic anisotropy ($v_2$) at low transverse momentum is considered as a hallmark of hydrodynamic collective flow. We investigate a multiphase transport (AMPT) model where the $v_2$ is mainly generated by an anisotropic escape mechanism, not of the hydrodynamic flow nature, and where mass splitting is also observed. We demonstrate that the $v_2$ mass splitting in AMPT is small right after hadronization (especially when resonance decays are included); the mass splitting mainly comes from hadronic rescatterings, even though their contribution to the overall charged hadron $v_2$ is small. These findings are qualitatively the same as those from hybrid models that combine hydrodynamics with a hadron cascade. We further show that there is no qualitative difference between heavy ion collisions and small system collisions. Our results indicate that the $v_2$ mass splitting is not a unique signature of hydrodynamic collective flow and thus cannot distinguish whether the elliptic flow is generated mainly from hydrodynamics or the anisotropic parton escape., Comment: 5 pages, 4 figures

Background: The different body components may contribute to the development of insulin resistance and type 2 diabetes mellitus. The aim of the present study was to examine the association of fat mass and fat free mass indices with markers of insulin resistance, independently of each other and giving, at the same time, gender-specific information in a wide cohort of European adolescents. Methods: A cross-sectional study in a school setting was conducted in 925 (430 males) adolescents (14.9 +/- 1.2 years). Weight, height, anthropometric, bioimpedance and blood parameters were measured. Indices for fat mass and fat free mass, and homeostatic model assessment (HOMA) were calculated. Multiple regression analyses were performed adjusting for several confounders including fat free mass and fat mass when possible. Results: Indices of fat mass were positively associated with HOMA (all p < 0.01) after adjusting for all the confounders including fat free mass indices, in both sexes. Fat free mass indices were associated with HOMA, in both males and females, after adjusting for center, pubertal status, socioeconomic status and cardiorespiratory fitness, but the associations disappear when including fat mass indices in the adjustment's model. Conclusion: Fat mass indices derived from different methods are positively associated with insulin resistance independently of several confounders including fat free mass indices. In addition, the relationship of fat free mass with insulin resistance is influenced by the amount of fat mass in European adolescents. Nevertheless, future studies should focus not only on the role of fat mass, but also on other body components such as fat free mass because its role could vary depending of the level and distribution of fat mass.

The authors' aim in this cross-sectional study was to characterize levels of objectively measured physical activity and sedentary time in adolescents from 9 European countries. The study comprised 2,200 European adolescents (1,184 girls) participating in the HELENA cross-sectional study (2006-2008). Physical activity was measured by accelerometry and was expressed as average intensity (counts/minute) and amount of time (minutes/day) spent engaging in moderate- to vigorous-intensity physical activity (MVPA). Time spent in sedentary behaviors was also objectively measured. Cardiorespiratory fitness was measured by means of the 20-m shuttle run test. Level of maternal education was reported by the adolescents. A higher proportion of boys (56.8% of boys vs. 27.5% of girls) met the physical activity recommendations of at least 60 minutes/day of MVPA. Adolescents spent most of the registered time in sedentary behaviors (9 hours/day, or 71% of the registered time). Both average intensity and MVPA were higher in adolescents with high cardiorespiratory fitness, and sedentary time was lower in the high-fitness group. There were no physical activity or sedentary time differences between maternal education categories. These data provide an objective measure of physical activity and amount of time spent in sedentary behaviors in a relatively large number of European adolescents.

In an earlier work (arXiv:0808.0953) we established that causal Israel-Stewart viscous hydrodynamics is only accurate in RHIC applications at very low shear viscosities 4 pi eta_s / s < ~ 1.5-2. We show here that the region of applicability is significantly reduced if bulk viscosity plays a role in the dynamics., Presentation at Quark Matter 2009 - contribution to the proceedings. v2: very minor changes in text and labels in Fig. 1

Coherent multiple scatterings of c c ¯ quark pairs in the environment of heavy ion collisions have been used in a previous work by Qiu et al. [J. Qiu, J.P. Vary, X. Zhang, Phys. Rev. Lett. 88 (2002) 232301; J. Qiu, J.P. Vary, X. Zhang, Nucl. Phys. A 698 (2002) 571, nucl-th/0106040] to study J / ψ suppression. That model suggests that heavy quark re-scatterings in a cold nuclear medium can completely explain the centrality dependence of the observed J / ψ suppression in Pb + Pb collisions at the SPS [M.C. Abreu, et al., NA50 Collaboration, Phys. Lett. B 521 (2001) 195]. Their calculations also revealed significant differences under the assumptions of a color singlet or color octet production mechanism. A more recent analytic calculation [H. Fujii, Phys. Rev. C 67 (2003) 031901], which includes incoherent final-state re-scatterings with explicit momentum transfer fluctuations in three dimensions, indicates much less suppression and little sensitivity to the production mechanism. In this Letter, we study simultaneously both the J / ψ suppression and p T modifications, at SPS and RHIC energies. We mainly focus on incoherent momentum transfer fluctuations in two dimensions, which is more appropriate for the heavy-ion collision kinematics. Our analytic and Monte Carlo calculations reinforce the analytic results in [H. Fujii, Phys. Rev. C 67 (2003) 031901]. Additionally, we find that the experimental J / ψ suppression and 〈 p T 2 〉 from nucleus–nucleus collisions at the SPS or RHIC cannot simultaneously be described in this incoherent multiple scattering framework for any value of the fluctuation strength parameter 〈 k T 2 〉 .

We trace the development of elliptic anisotropy ($v_2$) via parton-parton collision history in two transport models. The parton $v_2$ is studied as a function of the number of collisions of each parton in Au+Au and $d$+Au collisions at $\sqrt{s_{_{\rm NN}}}=200$ GeV. It is found that the majority of $v_2$ comes from the anisotropic escape probability of partons, with no fundamental difference at low and high transverse momenta. The contribution to $v_2$ from hydrodynamic-type collective flow is found to be small. Only when the parton-parton cross-section is set unrealistically large does this contribution start to take over. Our findings challenge the current paradigm emerged from hydrodynamic comparisons to anisotropy data., Comment: 6 pages, 7 figures. Version update: v2: extended study using both AMPT and MPC; varied parton cross sections; conclusions unchanged and scope expanded. v3: title made more

To examine the association between food groups consumption and vitamin BIn total 2189 individuals participating in the cross-sectional Healthy Lifestyle in Europe by Nutrition in Adolescence study met the eligibility criteria for analysis of dietary intakes (46 % males) and 632 for biomarker analysis (47 % males). Food intakes were assessed by two non-consecutive 24-h recalls. Biomarkers were measured by chromatography and immunoassay. Food groups which best discriminated participants in the extreme tertiles of the distribution of vitamins were identified by discriminant analyses. Food groups with standardised canonical coefficients higher or equal to 0.3 were selected as valid discriminators of vitamins intake and biomarkers extreme tertiles. Linear mixed model elucidated the association between food groups and vitamins intakes and biomarkers.Vitamin BWhereas B-vitamin intakes were associated with their food sources, biomarkers did with overall food consumption. Low-nutrient-density foods may compromise adolescents' vitamin status.

During the 5-year funding period (2010-2015), the JET Collaboration carried out a comprehensive research program with coordinated efforts involving all PI members and external associated members according to the plan and milestones outlined in the approved JET proposal. We identified important issues in the study of parton energy loss and made significant progress toward NLO calculations; advanced event-by-event hydrodynamic simulations of bulk matter evolution; developed Monte Carlo tools that combine different parton energy loss approaches, hydrodynamic models and parton recombination model for jet hadronization; and carried out the first comprehensive phenomenological study to extract the jet transport parameter.

International audience; Objective: To assess the relationships among physical activity, measured objectively, and attention capacity in European adolescents.Study design: The study included 273 adolescents, aged 12.5-17.5 years, who participated in the Healthy Lifestyle in Europe by Nutrition in Adolescence Study. Participants wore a uniaxial accelerometer for 7 days to measure physical activity. The d2 Test of Attention was administered to assess attention capacity. Multivariate analyses were used to study the association of attention capacity with each measure of physical activity. Receiver operating characteristic analysis was performed to determine thresholds that best discriminate between low and good attention capacity.Results: After controlling for potential confounding variables (age, sex, body mass index, parental educational level, fat mass, aerobic fitness, and center), adolescents' attention capacity test performances were significantly and positively associated with longer time spent in moderate or moderate-to-vigorous physical activity (MVPA) in free-living conditions (P < .05). Receiver operating characteristic curve analyses revealed that the physical activity thresholds that best discriminated between low/good attention capacities were ≥41 min·day−1 for moderate, ≥12 min·day−1 for vigorous, and ≥58 min·day−1 for MVPA.Conclusion:These findings suggest that promoting MVPA may be have a beneficial effect on attention capacity, an important component of cognition, in adolescents.

From covariant transport theory, a significant ~10% light quark elliptic flow at RHIC implies an elliptic flow of similar magnitude for charm quarks, at moderately large pT > 2.5 - 3 GeV. At lower transverse momenta, charm quark elliptic flow reduces progressively, reminiscent of the mass ordering pattern in ideal hydrodynamics. From the quark flows we predict the elliptic flow of D mesons at RHIC via quark coalescence. The large parton opacities needed to generate the light quark flow also lead to substantial ~40-50% secondary charm production., Talk at Hot Quarks 2004 (July 18-25, Taos, New Mexico) - to appear in proceedings. 7 pages, 5 EPS figs

High blood pressure (HBP) is one of the most important risk factors for cardiovascular diseases and it has a high prevalence in pediatric populations. However, the determinants of the incidence of Pre-HBP and HBP in children are not well known. i) To describe the incidence of HBP in European children; and ii) to evaluate the effect of physical activity (PA) and sedentary behavior (SB) on the Pre-HBP and HBP.The IDEFICS cohort study. A total of 16,228 children 2-9years at baseline were recruited by complex sampling population-based survey in eight European countries. At baseline (T0), 5221 children were selected for accelerometer measurements; 5061 children were re-examined 2years later (T1). We estimated the incidence of Pre-HBP and HBP and evaluate the effect of PA and SB on the Pre-HBP and HBP, by computing relative risks and the corresponding 95% confidence intervals (RR, 95% CI).Incidences of Pre-HBP and HBP per year were: 121/1000 children and 110/1000 children, respectively. We found that children maintaining SB2h/d during the two year follow-up showed a RR of having HBP of 1.28 (1.03-1.60). Children in T1 not performing the recommended amount of PA (60min/d) have a RR of HBP of 1.53 (1.12 to 2.09). We found no association between pre-HBP and the behaviors.The incidence of pre-HBP and HBP is high in European children. Maintaining sedentary behaviors during childhood increases the risk of developing HBP after two years of follow-up.

Comparing hydrodynamic simulations to heavy-ion data inevitably requires the conversion of the fluid to particles. This conversion, typically done in the Cooper-Frye formalism, is ambiguous for viscous fluids. We compute self-consistent phase space corrections by solving the linearized Boltzmann equation and contrast the solutions to those obtained using the ad-hoc "democratic Grad" ansatz typically employed in the literature where coefficients are independent of particle dynamics. Solutions are calculated analytically for a massless gas and numerically for both a pion-nucleon gas and for the general case of a hadron resonance gas. We find that the momentum dependence of the corrections in all systems investigated is best fit by a power close to 3/2 rather than the typically used quadratic ansatz. The effects on harmonic flow coefficients $v_2$ and $v_4$ are substantial, and should be taken into account when extracting medium properties from experimental data., 8 pages, 10 figures. Proceedings from the Winter Workshop on Nuclear Dynamics 2014 in Galveston, TX, USA

Comparison of hydrodynamic and "hybrid" hydrodynamics+transport calculations to heavy-ion data inevitably requires the conversion of the fluid to particles. For dissipative fluids the conversion is ambiguous without additional theory input complementing hydrodynamics. We obtain self-consistent shear viscous phase space corrections from linearized Boltzmann transport theory for a gas of hadrons. These corrections depend on the particle species, and incorporating them in Cooper-Frye freezeout affects identified particle observables. For example, with additive quark model cross sections,proton elliptic flow is larger than pion elliptic flow at moderately high $p_T$ in $Au+Au$ collisions at RHIC. This is in contrast to Cooper-Frye freezeout with the commonly used "democratic Grad" ansatz that assumes no species dependence. Various analytic and numerical results are also presented for massless and massive two-component mixtures to aid the interpretation. Self-consistent viscous corrections for each species are tabulated in Appendix F for convenient inclusion in pure hydrodynamic and hybrid calculations., Comment: Typo fixes and ambiguous language clarified, updated grant number and references, added Section IV-C with Fig. 4 as well as Section V-C with Fig. 9, Tables in Appendix G in single column journal style. (15 EPS plots, 33 pages, RevTeX style)

New numerical solutions of 3+1D covariant kinetic theory are reported for nuclear collisions in the energy domain Ecm∼200 AGeV. They were obtained using the MPC 0.1.2 parton transport code employing high parton subdivision to retain Lorentz covariance. The solutions are compared to those of relativistic hydrodynamics employing Cooper–Frye isotherm freeze-out. The transport solutions follow a different dynamical path than hydrodynamics due to large dissipative effects when pQCD scattering rates and HIJING initial conditions are assumed. The transport freeze-out four-volume is sensitive to the reaction rates. The final transverse momentum distributions are found to deviate by up to an order of magnitude from those of Cooper–Frye frozen hydrodynamics.

Identified particle observables from viscous hydrodynamics are sensitive to the fluid-to-particle conversion. Instead of the commonly assumed "democratic" Grad ansatz for phase space corrections $\delta f$, we utilize corrections calculated from linearized covariant transport theory. Estimates based on a pion-proton system with binary collisions indicate that protons are much closer to equilibrium than pions, significantly affecting the dissipative reduction of differential elliptic flow in Au+Au at RHIC. In addition, we test linear response against fully nonlinear transport for a two-component massless system in a Bjorken scenario. Strikingly, we find that, while linear response accounts well for the dynamical sharing of shear stress, the momentum dependence of phase space corrections is best described by Grad's quadratic ansatz, and not the linear response solution., Comment: Quark Matter 2011 contribution - 4 pages, uses IOP style files

It is unclear how much physical activity is necessary to prevent obesity during adolescence.The purpose of this study was to examine whether the current physical activity guidelines for youth are associated with a lower risk of excess of body fat in European adolescents.A sample of 2094 adolescents from the HELENA cross-sectional study was selected. Levels of moderate, vigorous, and moderate to vigorous physical activity (MVPA) were assessed using accelerometers. BMI and percentage of body fat (skinfolds) were calculated and used to categorize the adolescents as normal-weight/normal-fat, overweight/overfat, and obese. Data were collected during 2006-2007. Receiver operating characteristic (ROC) analysis, performed in 2009, was used to determine thresholds that best discriminate between weight and body fat categories.ROC analysis showed that/=18 minutes/day in vigorous physical activity and/=55 minutes/day in MVPA significantly discriminated between normal-weight and overweight+obesity categories. Moreover,/=9 minutes/day of vigorous physical activity and/=49 minutes/day of MVPA discriminated between normal-fat and overfat/obese adolescents. Adolescents who did not meet the current physical activity guidelines for youth of 60 minutes/day in MVPA increased the risk of having overweight+obesity (OR=1.24, 95% CI=1.01, 1.534) and overfat+obesity (OR=1.79, 95% CI=1.33, 2.42). ORs increased when adolescents did not meet the guidelines of at least 15 minutes/day in vigorous physical activity.Current physical activity guidelines seem to be appropriate to prevent excess of body fat in European adolescents. However, participation in vigorous physical activity might have additional importance in preventing obesity.

We utilize nonequilibrium covariant transport theory to determine the region of validity of causal Israel-Stewart dissipative hydrodynamics (IS) and Navier-Stokes theory (NS) for relativistic heavy ion physics applications. A massless ideal gas with 2->2 interactions is considered in a 0+1D Bjorken scenario, appropriate for the early longitudinal expansion stage of the collision. In the scale invariant case of a constant shear viscosity to entropy density ratio eta/s ~ const, we find that Israel-Stewart theory is 10% accurate in calculating dissipative effects if initially the expansion timescale exceeds half the transport mean free path tau0/lambda0 > ~2. The same accuracy with Navier-Stokes requires three times larger tau0/lambda0 > ~6. For dynamics driven by a constant cross section, on the other hand, about 50% larger tau0/lambda0 > ~3 (IS) and ~9 (NS) are needed. For typical applications at RHIC energies s_{NN}**(1/2) ~ 100-200 GeV, these limits imply that even the Israel-Stewart approach becomes marginal when eta/s > ~0.15. In addition, we find that the 'naive' approximation to Israel-Stewart theory, which neglects products of gradients and dissipative quantities, has an even smaller range of applicability than Navier-Stokes. We also obtain analytic Israel-Stewart and Navier-Stokes solutions in 0+1D, and present further tests for numerical dissipative hydrodynamics codes in 1+1, 2+1, and 3+1D based on generalized conservation laws., 30 pages, 26 EPS figures, revtex stylefile

An intriguing potential signature of hydrodynamic behavior in relativistic A+A reactions at Relativistic Heavy Ion Collider (RHIC) energies is conical flow induced by fast supersonic particles traversing the hot and dense medium. Here I present first results on the evolution of Mach shocks in 2->2 covariant transport theory, in a static uniform medium., Presentation at CIPANP 2009 (Tenth Conference on the Intersections of Particle and Nuclear Physics), May 26-31, 2009, Torrey Pines, California, USA

We compare 2->2 covariant transport theory and causal Israel-Stewart hydrodynamics in 2+1D longitudinally boost invariant geometry with RHIC-like initial conditions and a conformal e = 3p equation of state. The pressure evolution in the center of the collision zone and the final differential elliptic flow v2(pT) from the two theories agree remarkably well for a small shear viscosity to entropy density ratio eta/s ~ 1/(4 pi), and also for a large cross section sigma ~ 50 mb. A key to this agreement is keeping ALL terms in the Israel-Stewart equations of motion. Our results indicate promising prospects for the applicability of Israel-Stewart dissipative hydrodynamics at RHIC, provided the shear viscosity of hot and dense quark-gluon matter is indeed very small for the relevant temperatures T ~ 200-500 MeV., Presentation at Quark Matter 2008. 4 pages, 3 figures