Gunn domain existence in the channel of a saturated GaAs MESFET

The existence of a Gunn domain in the channel of a GaAs MESFET after saturation is confirmed through numerical bidimensional simulation, but the i D vs. VDS decrease is not observed. It is shown that in devices including an interfacial space charge layer, the accumulation bump of the domain is responsible for an opening of the channel by which the leakage current is flowing

Gunn domain existence in the channel of a saturated GaAs MESFET

The existence of a Gunn domain in the channel of a GaAs MESFET after saturation is confirmed through numerical bidimensional simulation, but the i D vs. VDS decrease is not observed. It is shown that in devices including an interfacial space charge layer, the accumulation bump of the domain is responsible for an opening of the channel by which the leakage current is flowing.L'existence d'un domaine de Gunn dans le canal d'un MESFET GaAs après saturation est confirmée par une simulation numérique bidimensionnelle, mais son apparition ne produit pas de décroissance du courant de drain. On montre que dans les dispositifs comportant une zone de charge d'espace à l'interface entre couche et substrat la zone d'accumulation du domaine provoque un élargissement du canal responsable de la circulation d'un courant excédentaire, sans que le substrat soit sollicité

Does puberty alter dietary habits in adolescents living in a western society?

PURPOSE: Puberty is considered to be a period with major behavioral changes and alterations in lifestyle. It is also assumed that important modifications in food habits would occur during pubertal maturation, particularly in affluent societies. To test this hypothesis, we conducted a prospective survey in 193 adolescents (95 females and 98 males) aged 9-19 years. METHODS: Food intake was assessed using a 5-day dietary diary method with weighing of most food intakes. Diaries were analyzed for macronutrient consumption with a nutrition determination software integrating food composition tables and 103 local food items. The stage of puberty or sexual maturity was clinically assessed and rated from stage P1 (prepubertal) to P5 (adult). RESULTS: The total energy intake which was within the recommended dietary allowances (RDA) was significantly influenced by both pubertal maturation and sex when expressed in absolute terms, but by pubertal stages only when adjusted per kilogram of body weight. Compared with RDA, the macronutrient distribution of the total energy intake showed an excessive quantity of fat (especially saturated fatty acids) and an insufficient amount of carbohydrate-rich fibers. The intakes of proteins, of which two out of three came from animal sources, were above RDA. Overall, these inadequacies in the macronutrient intake distribution were constant throughout pubertal maturation. CONCLUSION: This study indicates that the type of diet which has been linked with several chronic diseases in adults living in developed countries already prevails before pubertal maturation. This dietary pattern changes marginally during pubertal development. Therefore, our investigation does not support the notion that "bad" food habits become particularly worse during the years of pubertal maturation

Interaction between calcium intake and menarcheal age on bone mass gain: an eight-year follow-up study from prepuberty to postmenarche.

Both late menarcheal age and low calcium intake (Ca intake) during growth are risk factors for osteoporosis, probably by impairing peak bone mass. We investigated whether lasting gain in areal bone mineral density (aBMD) in response to increased Ca intake varies according to menarcheal age and, conversely, whether Ca intake could influence menarcheal age. In an initial study, 144 prepubertal girls were randomized in a double-blind controlled trial to receive either a Ca supplement (Ca-suppl.) of 850 mg/d or placebo from age 7.9-8.9 yr. Mean aBMD gain determined by dual energy x-ray absorptiometry at six sites (radius metaphysis, radius diaphysis, femoral neck, trochanter, femoral diaphysis, and L2-L4) was significantly (P = 0.004) greater in the Ca-suppl. than in the placebo group (27 vs. 21 mg/cm(2)). In 122 girls followed up, menarcheal age was recorded, and aBMD was determined at 16.4 yr of age. Menarcheal age was lower in the Ca-suppl. than in the placebo group (P = 0.048). Menarcheal age and Ca intake were negatively correlated (r = -0.35; P < 0.001), as were aBMD gains from age 7.9-16.4 yr and menarcheal age at all skeletal sites (range: r = -0.41 to r = -0.22; P < 0.001 to P = 0.016). The positive effect of Ca-suppl. on the mean aBMD gain from baseline remained significantly greater in girls below, but not in those above, the median of menarcheal age (13.0 yr). Early menarcheal age (12.1 +/- 0.5 yr): placebo, 286 +/- 36 mg/cm(2); Ca-suppl., 317 +/- 46 (P = 0.009); late menarcheal age (13.9 +/- 0.5 yr): placebo, 284 +/- 58; Ca-suppl., 276 +/- 50 (P > 0.05). The level of Ca intake during prepuberty may influence the timing of menarche, which, in turn, could influence long-term bone mass gain in response to Ca supplementation. Thus, both determinants of early menarcheal age and high Ca intake may positively interact on bone mineral mass accrual

Later menarche is associated with increased risk of fracture during growth and with reduced bone strength as assessed by fea at distal tibia in healthy 20-year old and in premenopausal women

Abstract OC 18 : European Congress on Osteoporosis & Osteoarthritis (IOF-ECCEO12

Later menarche is associated with increased risk of fracture during growth and with reduced bone strength as assessed by fea at distal tibia in healthy 20-year old and in premenopausal women

Abstract OC 18 : European Congress on Osteoporosis & Osteoarthritis (IOF-ECCEO12