[Continuum of risky eating behaviors in Mexican adolescents]

OBJECTIVE: Determine the relationship between the variables of self-esteem (SE), body dissatisfaction (BD), and body mass index (BMI) in a continuum of risky eating behaviors (REB) that ranges from normal behavior to the risk of eating disorders (ED), thus facilitating early detection of adolescents with ED symptomatology and the degree to which such variables have an influence. METHODS: A total of 1 982 young women aged 15-19 were selected through stratified random sampling. Self-esteem (Pope, McHale, and Craighead scale), body dissatisfaction (Stunkard's Figure Rating Scale), and body mass index were measured. A brief REB questionnaire was administered. Three categories of REB were defined: no risk, moderate risk, and high risk. A multiple regression analysis was performed. RESULTS: A direct relationship was found between risk of REB and BD, with significant differences between the groups (P < 0.001): no risk (83.6% of sample), 54.1% had BD; moderate risk (11.9% of sample), 84.8% had BD; and high risk (4.5% of sample), 89.9% had BD. There were significant differences in SE and BMI only between the group with no risk and each of the risk groups. Self-esteem played a role in predicting REB in all the regression models evaluated, whereas BMI did not. CONCLUSIONS: It is essential to identify adolescents at moderate risk of REB who have prodromic features of ED such as low SE and BD. When these features occur simultaneously, they can mediate a negative effect of BMI on REB

[Continuum of risky eating behaviors in Mexican adolescents]

OBJECTIVE: Determine the relationship between the variables of self-esteem (SE), body dissatisfaction (BD), and body mass index (BMI) in a continuum of risky eating behaviors (REB) that ranges from normal behavior to the risk of eating disorders (ED), thus facilitating early detection of adolescents with ED symptomatology and the degree to which such variables have an influence. METHODS: A total of 1 982 young women aged 15-19 were selected through stratified random sampling. Self-esteem (Pope, McHale, and Craighead scale), body dissatisfaction (Stunkard's Figure Rating Scale), and body mass index were measured. A brief REB questionnaire was administered. Three categories of REB were defined: no risk, moderate risk, and high risk. A multiple regression analysis was performed. RESULTS: A direct relationship was found between risk of REB and BD, with significant differences between the groups (P < 0.001): no risk (83.6% of sample), 54.1% had BD; moderate risk (11.9% of sample), 84.8% had BD; and high risk (4.5% of sample), 89.9% had BD. There were significant differences in SE and BMI only between the group with no risk and each of the risk groups. Self-esteem played a role in predicting REB in all the regression models evaluated, whereas BMI did not. CONCLUSIONS: It is essential to identify adolescents at moderate risk of REB who have prodromic features of ED such as low SE and BD. When these features occur simultaneously, they can mediate a negative effect of BMI on REB

Ultrafast electron diffuse scattering and its application to 2D materials

The nature of the couplings within and between lattice and charge degrees of freedom is central to condensed matter and materials physics. Despite their fundamental role, detailed momentum-dependent information on the strength of electron-phonon and phonon-phonon couplings across all momenta has proved elusive. Ultrafast electron diffuse scattering provides the answer by measuring momentum-dependent phonon population dynamics similar to how time and angle resolved photoemission spectroscopy views the momentum-dependent occupation dynamics of electronic states. This method proves particularly effective in the study of 2D materials. A sophisticated analysis applied to ultrafast electron scattering measurements of graphite, follows the cascade of electron-phonon and phonon-phonon couplings after pulsed laser excitation in this well studied benchmark system. In a similar experiment on titanium diselenide, electronphonon coupling is measured by observing the effect of photoexcitation on the renormalized phonon frequencies with the characteristic momentum of titanium diselenide's charge density wave transition. Through its sensitivity to transient phonon occupancies and frequencies, ultrafast electron diffuse scattering is a novel and powerful method to unravel the physics of complex phases and properties determined through interplay between the electron and lattice systems.La nature du couplage entre le réseau d'atomes et les porteurs de charges d'un cristal est centrale au domaine de la physique de la matière condensée. Malgré leurs rôles fondamentaux, les couplages électron-phonon et phonon-phonon demeurent mystérieux. La diffraction ultrarapide diffusé par électrons permet de répondre aux questions concernant l'occupation des populations phononiques dans l'entièreté de l'espace réciproque. Plus spécifiquement, les excitations optiques sur un cristal de graphite, initiées par une impulsion laser femtoseconde, génèrent une population électronique excitée particulière, appelée cônes de Dirac. Ces excitations creés un plasma d'´electrons et de trous de densité variable, contrôlée par l'intensité de l'impulsion laser. Cette thèse présente une analyse sophistiquée de données de diffraction ultrarapide diffusé par électrons faisant la lumière sur la relaxation du système électronique excité par impulsion ultrarapide, passant par le couplage avec le réseau d'atomes, puis finissant en relaxation des modes phononiques avec l'environnement. Dans le cas du disélénure de titane (TiSe2), le couplage électron-phonon est mesuré de façon complètement différente; en observant l'effet de la photo-excitation sur les fréquences de phonons renormalisées aux vecteurs d'ondes caractéristiques de la phase d'ondes de charges de TiSe2. A travers la sensitivité aux occupations phononiques temporaires, la diffraction 'ultrarapide diffusé par électrons permet de d´ecortiquer la physique des phases complexes de la matière, et d'élucider la relation entre le système ´electronique et le réseau d'atomes

Prevalence and associated factors related to disordered eating in student adolescents of Guadalajara across sex [Prevalencia y factores asociados a las conductas alimentarias de riesgo en adolescentes escolares de Guadalajara según sexo]

Objective. To determine the prevalence and associated factors to disordered eating (DE) in adolescents by sex. Material and methods. A transversal and analytic study was carried out with 1,134 first grade students at a public high school. Self esteem, impulsivity, depressive symptoms, suicidal ideation, entertainment, locus of control, relationship with father/mother, stress and DE were assessed with previously validated and standardized scales. Results. A prevalence of 7.2% of risky eating behaviors was obtained; 2.8% for men and 10.3% for women. In men in the risk analysis the association was maintained for impulsivity, depressive symptoms, suicidal ideation and stress. After the multivaried analysis only depression and stress showed any association. In women in the risk analysis, the association was maintained for impulsivity, depressive symptoms, suicidal ideation and stress, and after the multivaried analysis only impulsivity, suicidal ideation and stress maintained the association. Conclusions. The prevalence of DE was higher among women. The associated factors in men were depressive symptoms and stress, whilst for women was impulsivity, suicidal ideation and stress

Prevalence and associated factors related to disordered eating in student adolescents of Guadalajara across sex [Prevalencia y factores asociados a las conductas alimentarias de riesgo en adolescentes escolares de Guadalajara según sexo]

Objective. To determine the prevalence and associated factors to disordered eating (DE) in adolescents by sex. Material and methods. A transversal and analytic study was carried out with 1,134 first grade students at a public high school. Self esteem, impulsivity, depressive symptoms, suicidal ideation, entertainment, locus of control, relationship with father/mother, stress and DE were assessed with previously validated and standardized scales. Results. A prevalence of 7.2% of risky eating behaviors was obtained; 2.8% for men and 10.3% for women. In men in the risk analysis the association was maintained for impulsivity, depressive symptoms, suicidal ideation and stress. After the multivaried analysis only depression and stress showed any association. In women in the risk analysis, the association was maintained for impulsivity, depressive symptoms, suicidal ideation and stress, and after the multivaried analysis only impulsivity, suicidal ideation and stress maintained the association. Conclusions. The prevalence of DE was higher among women. The associated factors in men were depressive symptoms and stress, whilst for women was impulsivity, suicidal ideation and stress

Disordered eating behaviors: Prevalence among Mexican students aged 15-19 [Conductas alimentarias de riesgo: Prevalencia en estudiantes mexicanas de 15 a 19 años]

Objective. To obtain the prevalence of disordered eating (DE) among student female adolescents from public high schools in 17 urban settings in the Mexican Republic, across age, setting and region. Material and methods. The sample comprised 4,358 female students 15 to 19 years of age. DE was evaluated with a validated and standardized questionnaire for Mexican adolescents with 2 cutoff points: moderate-DE and high-DE. Results. The total prevalence of moderate-DE was 14.2% and 6.8% for high-DE. Significant statistical differences were found only for high-DE across settings, were the Estado de Mexico reached the highest score (12.1%) and Aguascalientes the lowest (2.1%). The north region obtained the highest scores for both moderate (17.2%) and high-DE (9.7%), whereas the center-west region obtained the second place for moderate-DE (15.1%) and the center region for high-DE (11.5%). The center region showed the lowest scores for moderate-DE (11.5%) and the south-southeast region the lowest for high-DE (4.5%). The analysis across age showed a positive relationship for both moderate and high-DE. Conclusions. The total prevalence of DE was 6.8%. Age, socioeconomic status and the place of residence seem to be variables that relate to disordered eating

Disordered eating behaviors: Prevalence among Mexican students aged 15-19 [Conductas alimentarias de riesgo: Prevalencia en estudiantes mexicanas de 15 a 19 años]

Objective. To obtain the prevalence of disordered eating (DE) among student female adolescents from public high schools in 17 urban settings in the Mexican Republic, across age, setting and region. Material and methods. The sample comprised 4,358 female students 15 to 19 years of age. DE was evaluated with a validated and standardized questionnaire for Mexican adolescents with 2 cutoff points: moderate-DE and high-DE. Results. The total prevalence of moderate-DE was 14.2% and 6.8% for high-DE. Significant statistical differences were found only for high-DE across settings, were the Estado de Mexico reached the highest score (12.1%) and Aguascalientes the lowest (2.1%). The north region obtained the highest scores for both moderate (17.2%) and high-DE (9.7%), whereas the center-west region obtained the second place for moderate-DE (15.1%) and the center region for high-DE (11.5%). The center region showed the lowest scores for moderate-DE (11.5%) and the south-southeast region the lowest for high-DE (4.5%). The analysis across age showed a positive relationship for both moderate and high-DE. Conclusions. The total prevalence of DE was 6.8%. Age, socioeconomic status and the place of residence seem to be variables that relate to disordered eating