Context-dependent interactions and the regulation of species richness in freshwater fish

Species richness is regulated by a complex network of scale-dependent processes. This complexity can obscure the influence of limiting species interactions,

Voluntary and Electrically Evoked Strength Characteristics of Obese and Nonobese Preadolescent Boys

Overweight and obese children demonstrate inferior motor performance for strength- and power-related activities requiring support or lifting of body weight. Our purpose here was to determine whether the inferior performance could be attributed to a lower strength to muscle area ratio in the obese. Eleven nonobese (16.6% fat) and 13 obese (35.5% fat) boys (9-13 years old) volunteered for the study. Peak torque was measured during voluntary isometric and isokinetic elbow flexion and knee extension at four joint angles and four velocities, respectively. The contractile properties, twitch torque, time to peak torque, and half-relaxation time were evoked for the elbow flexors by percutaneous stimulation. Elbow flexor and knee extensor cross-sectional areas (CSA) were determined by computed axial tomography taken at the mid-upper arm and mid-thigh, respectively. Isometric and isokinetic elbow flexion and knee extension strength normalized for body weight were significantly (p \u3c 0.05) higher in the nonobese compared to the obese boys. There were no significant (p \u3e 0.05) differences, however, between groups for elbow flexor and knee extensor CSA or for absolute and relative (normalized for muscle CSA or the product of muscle CSA and height, the latter accounting for differences in moment arm length) isometric, isokinetic, or evoked twitch torque for elbow flexion or knee extension. Likewise, there were no differences between groups for the timerelated contractile properties, time to peak torque, or half-relaxation time. These findings suggest that there is no difference in the intrinsic strength or contractile properties of the elbow flexor and knee extensor muscles between obese and nonobese pre-adolescent boys and that other factors, such as the handicapping effect of excess fat mass, probably account for the reduced motor performance of the obese child

Factors Influencing Color of Dark Cutting Beef Muscle

Color of dark cutting beef rib muscle was measured as affected by treatment with rotenone or chilling in an oxygen rich atmosphere. Samples homogenized with the mitochondrial inhibitor, rotenone, or pH 5.0 buffer remained red for up to 1 hr. Control samples blended with water remained red when chilled but turned dark when held at room temperature. Thin slices of dark cutting beef muscle would turn red when chilled in air or oxygen to 3°C, or when chilled in oxygen to 14°C, but would turn dark when transferred from oxygen at 3°C to air at room temperature. Thus, dark cutting beef muscle will turn red if mitochondrial respiration is inhibited, allowing myoglobin at muscle surfaces to remain oxygenated

Blanching Leafy Vegetables With Electromagnetic Energy

WOS: A1994PP03500026Application of radio frequency, microwave, microwave-steam and infrared energy for blanching of leafy vegetables (endive and spinach) was studied and compared with conventional hot water and steam blanching. The quality of vegetables both frozen and sterilized was evaluated by instrumental and sensory analysis. Effects of blanching methods were most pronounced in frozen products. No quality differences occurred for infrared and radio frequency treatments. However, microwave energy alone or in combination with steam in the blanching process improved vitamin C retention, gave higher Instron force values and better sensory characteristics