Characteristic Sizes of Life in the Oceans, from Bacteria to Whales.

The size of an individual organism is a key trait to characterize its physiology and feeding ecology. Size-based scaling laws may have a limited size range of validity or undergo a transition from one scaling exponent to another at some characteristic size. We collate and review data on size-based scaling laws for resource acquisition, mobility, sensory range, and progeny size for all pelagic marine life, from bacteria to whales. Further, we review and develop simple theoretical arguments for observed scaling laws and the characteristic sizes of a change or breakdown of power laws. We divide life in the ocean into seven major realms based on trophic strategy, physiology, and life history strategy. Such a categorization represents a move away from a taxonomically oriented description toward a trait-based description of life in the oceans. Finally, we discuss life forms that transgress the simple size-based rules and identify unanswered questions.

Maintenance of energy expenditure on high-protein vs. high-carbohydrate diets at a constant body weight may prevent a positive energy balance.

BACKGROUND & AIMS: Relatively high-protein diets are effective for body weight loss, and subsequent weight maintenance, yet it remains to be shown whether these diets would prevent a positive energy balance. Therefore, high-protein diet studies at a constant body weight are necessary. The objective was to determine fullness, energy expenditure, and macronutrient balances on a high-protein low-carbohydrate (HPLC) diet compared with a high-carbohydrate low-protein (HCLP) diet at a constant body weight, and to assess whether effects are transient or sustained after 12 weeks. METHODS: A randomized parallel study was performed in 14 men and 18 women [mean ± SD age: 24 ± 5 y; BMI (in kg/m(2)): 22.8 ± 2.0] on diets containing 30/35/35 (HPLC) or 5/60/35 (HCLP) % of energy from protein/carbohydrate/fat. RESULTS: Significant interactions between dietary intervention and time on total energy expenditure (TEE) (P = 0.013), sleeping metabolic rate (SMR) (P = 0.040), and diet-induced thermogenesis (DIT) (P = 0.027) appeared from baseline to wk 12. TEE was maintained in the HPLC diet group, while it significantly decreased throughout the intervention period in the HCLP diet group (wk 1: P = 0.002; wk 12: P = 0.001). Energy balance was maintained in the HPLC diet group, and became positive in the HCLP diet group at wk 12 (P = 0.008). Protein balance varied directly according to the amount of protein in the diet, and diverged significantly between the diets (P = 0.001). Fullness ratings were significantly higher in the HPLC vs. the HCLP diet group at wk 1 (P = 0.034), but not at wk 12. CONCLUSIONS: Maintenance of energy expenditure on HPLC vs. HCLP diets at a constant body weight may prevent development of a positive energy balance, despite transiently higher fullness. The study was registered on clinicaltrials.gov with Identifier: NCT01551238.

Distinct associations between energy balance and the sleep characteristics slow wave sleep and rapid eye movement sleep.

CONTEXT: Epidemiologically, an inverse relationship between body mass index (BMI) and sleep duration is observed. Intra-individual variance in the amount of slow wave sleep (SWS) or rapid eye movement (REM) sleep has been related to variance of metabolic and endocrine parameters, which are risk factors for the disturbance of energy balance (EB). OBJECTIVE: To investigate inter-individual relationships between EB (EB= energy intake-energy expenditure∣, MJ/24 h), SWS or REM sleep, and relevant parameters in normal-weight men during two 48 h stays in the controlled environment of a respiration chamber. SUBJECTS AND METHODS: A total of 16 men (age 23±3.7 years, BMI 23.9±1.9 kg m(-2)) stayed in the respiration chamber twice for 48 h to assure EB. Electroencephalography was used to monitor sleep (2330-0730 hrs). Hunger and fullness were scored by visual analog scales; mood was determined by State Trait Anxiety Index-state and food reward by liking and wanting. Baseline blood and salivary samples were collected before breakfast. Subjects were fed in EB, except for the last dinner, when energy intake was ad libitum. RESULTS: The subjects slept on average 441.8±49 min per night, and showed high within-subject reliability for the amount of SWS and REM sleep. Linear regression analyses showed that EB was inversely related to the amount of SWS (r=-0.43, P<0.03), and positively related to the amount of REM sleep (r=0.40, P<0.05). Relevant parameters such as hunger, reward, stress and orexigenic hormone concentrations were related to overeating, as well as to the amount of SWS and REM sleep, however, after inclusion of these parameters in a multiple regression, the amount of SWS and REM sleep did not add to the explained variance of EB, which suggests that due to their individual associations, these EB parameters are mediator variables. CONCLUSION: A positive EB due to overeating, was explained by a smaller amount of SWS and higher amount of REM sleep, mediated by hunger, fullness, State Trait Anxiety Index-state scores, glucose/insulin ratio, and ghrelin and cortisol concentrations.

Exact results for the Kuramoto model with a bimodal frequency distribution.

We analyze a large system of globally coupled phase oscillators whose natural frequencies are bimodally distributed. The dynamics of this system has been the subject of long-standing interest. In 1984 Kuramoto proposed several conjectures about its behavior; ten years later, Crawford obtained the first analytical results by means of a local center manifold calculation. Nevertheless, many questions have remained open, especially about the possibility of global bifurcations. Here we derive the system's stability diagram for the special case where the bimodal distribution consists of two equally weighted Lorentzians. Using an ansatz recently discovered by Ott and Antonsen, we show that in this case the infinite-dimensional problem reduces exactly to a flow in four dimensions. Depending on the parameters and initial conditions, the long-term dynamics evolves to one of three states: incoherence, where all the oscillators are desynchronized; partial synchrony, where a macroscopic group of phase-locked oscillators coexists with a sea of desynchronized ones; and a standing wave state, where two counter-rotating groups of phase-locked oscillators emerge. Analytical results are presented for the bifurcation boundaries between these states. Similar results are also obtained for the case in which the bimodal distribution is given by the sum of two Gaussians.