A Framework for Multiaccess Support for Unreliable Internet Traffic using Multipath DCCP

Mobile nodes are typically equipped with multiple radios and can connect to multiple radio access networks (e.g. WiFi, LTE and 5G). Consequently, it is important to design mechanisms that efficiently manage multiple network interfaces for aggregating the capacity, steering of traffic flows or switching flows among multiple interfaces. While such multi-access solutions have the potential to increase the overall traffic throughput and communication reliability, the variable latencies on different access links introduce packet delay variation which has negative effect on the application quality of service and user quality of experience. In this paper, we present a new IP-compatible multipath framework for heterogeneous access networks. The framework uses Multipath Datagram Congestion Control Protocol (MP-DCCP) - a set of extensions to regular DCCP - to enable a transport connection to operate across multiple access networks, simultaneously. We present the design of the new protocol framework and show simulation and experimental testbed results that (1) demonstrate the operation of the new framework, and (2) demonstrate the ability of our solution to manage significant packet delay variation caused by the asymmetry of network paths, by applying pluggable packet scheduling or reordering algorithms

Appetite and energy balancing

AbstractThe idea that food intake is motivated by (or in anticipation of) ‘hunger’ arising from energy depletion is apparent in both public and scientific discourse on eating behaviour. In contrast, our thesis is that eating is largely unrelated to short-term energy depletion. Energy requirements meal-to-meal are trivial compared with total body energy stores, and energy supply to the body's tissues is maintained if a meal or even several meals are missed. Complex and exquisite metabolic machinery ensures that this happens, but metabolic regulation is only loosely coupled with the control of energy intake. Instead, food intake needs to be controlled because the limited capacity of the gut means that processing a meal presents a significant physiological challenge and potentially hinders other activities. We illustrate the relationship between energy (food) intake and energy expenditure with a simple analogy in which: (1) water in a bathtub represents body energy content, (2) water in a saucepan represents food in the gut, and (3) the bathtub is filled via the saucepan. Furthermore, (4) it takes hours to process and pass the full energy (macronutrient) content of the saucepan to the bathtub, and (5) both the saucepan and bathtub resist filling, representing negative feedbacks on appetite (desire to eat). This model is consistent with the observations that appetite is reduced acutely by energy intake (a meal added to the limited capacity of the saucepan/gut), but not increased by an acute increase in energy expenditure (energy removed from the large store of energy in the bathtub/body). The existence of relatively very weak but chronic negative feedback on appetite proportional to body fatness is supported by observations on the dynamics of energy intake and weight gain in rat dietary obesity. (We use the term ‘appetite’ here because ‘hunger’ implies energy depletion.) In our model, appetite is motivated by the accessibility of food and the anticipated and experienced pleasure of eating it. The latter, which is similar to food reward, is determined primarily by the state of emptiness of the gut and food liking related to the food's sensory qualities and macronutrient value and the individual's dietary history. Importantly, energy density adds value because energy dense foods are less satiating kJ for kJ and satiation limits further intake. That is, energy dense foods promote energy intake by virtue (1) of being more attractive and (2) having low satiating capacity kJ for kJ, and (1) is partly a consequence of (2). Energy storage is adapted to feast and famine and that includes unevenness over time of the costs of obtaining and ingesting food compared with engaging in other activities. However, in very low-cost food environments with energy dense foods readily available, risk of obesity is high. This risk can be and is mitigated by dietary restraint, which in its simplest form could mean missing the occasional meal. Another strategy we discuss is the energy dilution achieved by replacing some sugar in the diet with low-calorie sweeteners. Perhaps as or more significant, though, is that belief in short-term energy balancing (the energy depletion model) may undermine attempts to eat less. Therefore, correcting narratives of eating to be consistent with biological reality could also assist with weight control

Effects of repeated consumption on sensory-enhanced satiety

Previous research suggests that sensory characteristics of a drink modify the acute satiating effects of its nutrients, with enhanced satiety evident when a high energy drink was thicker and tasted creamier. The present study tested whether this modulation of satiety by sensory context was altered by repeated consumption. Participants (n=48) consumed one of four drinks mid-morning on seven non-consecutive days with satiety responses measured pre-exposure (day 1), post-exposure (day 6) and at a one month follow-up. Drinks combined two levels of energy (lower energy, LE, 326 KJ: higher energy, HE, 1163KJ) with two levels of satiety-predictive sensory characteristics (low-sensory, LS, or enhanced sensory, ES). Test lunch intake 90 minutes after drink consumption depended on both the energy content and sensory characteristics of the drink before exposure, but on energy content alone at post-exposure and the follow-up. The largest change was an increase in test meal intake over time in the LE/LS condition. Effects on intake were reflected in appetite ratings, with rated hunger and expected filling affected by sensory characteristics and energy content pre-exposure, but were largely determined by energy content post exposure and at follow up. In contrast, a measure of expected satiety reflected sensory characteristics regardless of energy content on all three test days. Overall these data suggest that some aspects of the sensory-modulation of satiety are changed by repeated consumption, with covert energy becoming more effective in suppressing appetite over time, but also suggest that these behavioural changes are not readily translated into expectations of satiety

Effects of meal variety on expected satiation : evidence for a 'perceived volume' heuristic

Meal variety has been shown to increase energy intake in humans by an average of 29%. Historically, research exploring the mechanism underlying this effect has focused on physiological and psychological processes that terminate a meal (e.g., sensory-specific satiety). We sought to explore whether meal variety stimulates intake by influencing pre-meal planning. We know that individuals use prior experience with a food to estimate the extent to which it will deliver fullness. These ‘expected satiation’ judgments may be straightforward when only one meal component needs to be considered, but it remains unclear how prospective satiation is estimated when a meal comprises multiple items. We hypothesised that people simplify the task by using a heuristic, or ‘cognitive shortcut.’ Specifically, as within-meal variety increases, expected satiation tends to be based on the perceived volume of food(s) rather than on prior experience. In each trial, participants (N = 68) were shown a plate of food with six buffet food items. Across trials the number of different foods varied in the range one to six. In separate tasks, the participants provided an estimate of their combined expected satiation and volume. When meal variety was high, judgments of perceived volume and expected satiation ‘converged.’ This is consistent with a common underlying response strategy. By contrast, the low variety meals produced dissociable responses, suggesting that judgments of expected satiation were not governed solely by perceived volume. This evidence for a ‘volume heuristic’ was especially clear in people who were less familiar with the meal items. Together, these results are important because they expose a novel process by which meal variety might increase food intake in humans

Assimilation of healthy and indulgent impressions from labelling influences fullness but not intake or sensory experience

Background: Recent evidence suggests that products believed to be healthy may be over-consumed relative to believed indulgent or highly caloric products. The extent to which these effects relate to expectations from labelling, oral experience or assimilation of expectations is unclear. Over two experiments, we tested the hypotheses that healthy and indulgent information could be assimilated by oral experience of beverages and influence sensory evaluation, expected satiety, satiation and subsequent appetite. Additionally, we explored how expectation-experience congruency influenced these factors. Results: Results supported some assimilation of healthiness and indulgent ratings—study 1 showed that indulgent ratings enhanced by the indulgent label persisted post-tasting, and this resulted in increased fullness ratings. In study 2, congruency of healthy labels and oral experience promoted enhanced healthiness ratings. These healthiness and indulgent beliefs did not influence sensory analysis or intake—these were dictated by the products themselves. Healthy labels, but not experience, were associated with decreased expected satiety. Conclusions: Overall labels generated expectations, and some assimilation where there were congruencies between expectation and experience, but oral experience tended to override initial expectations to determine ultimate sensory evaluations and intake. Familiarity with the sensory properties of the test beverages may have resulted in the use of prior knowledge, rather than the label information, to guide evaluations and behaviour

Estimating everyday portion size using a 'method of constant stimuli': in a student sample, portion size is predicted by gender, dietary behaviour, and hunger, but not BMI

This paper (i) explores the proposition that body weight is associated with large portion sizes and (ii) introduces a new technique for measuring everyday portion size. In our paradigm, the participant is shown a picture of a food portion and is asked to indicate whether it is larger or smaller than their usual portion. After responding to a range of different portions an estimate of everyday portion size is calculated using probit analysis. Importantly, this estimate is likely to be robust because it is based on many responses. First-year undergraduate students (N=151) completed our procedure for 12 commonly consumed foods. As expected, portion sizes were predicted by gender and by a measure of dieting and dietary restraint. Furthermore, consistent with reports of hungry supermarket shoppers, portion-size estimates tended to be higher in hungry individuals. However, we found no evidence for a relationship between BMI and portion size in any of the test foods. We consider reasons why this finding should be anticipated. In particular, we suggest that the difference in total energy expenditure of individuals with a higher and lower BMI is too small to be detected as a concomitant difference in portion size (at least in our sample)

On a theorem of Y. Miyashita

Background: Portion size is an important driver of larger meals. However, effects on food choice remain unclear. Objective: Our aim was to identify how portion size influences the effect of palatability and expected satiety on choice. Methods: In Study 1, adult participants (n = 24, 87.5% women) evaluated the palatability and expected satiety of 5 lunchtime meals and ranked them in order of preference. Separate ranks were elicited for equicaloric portions from 100 to 800 kcal (100-kcal steps). In Study 2, adult participants (n = 24, 75% women) evaluated 9 meals and ranked 100–600 kcal portions in 3 contexts (scenarios), believing that 1) the next meal would be at 1900, 2) they would receive only a bite of one food, and 3) a favorite dish would be offered immediately afterwards. Regression analysis was used to quantify predictors of choice. Results: In Study 1, the extent to which expected satiety and palatability predicted choice was highly dependent on portion size (P < 0.001). With smaller portions, expected satiety was a positive predictor, playing a role equal to palatability (100-kcal portions: expected satiety, β: 0.42; palatability, β: 0.46). With larger portions, palatability was a strong predictor (600-kcal portions: β: 0.53), and expected satiety was a poor or negative predictor (600-kcal portions: β: −0.42). In Study 2, this pattern was moderated by context (P = 0.024). Results from scenario 1 replicated Study 1. However, expected satiety was a poor predictor in both scenario 2 (expected satiety was irrelevant) and scenario 3 (satiety was guaranteed), and palatability was the primary driver of choice across all portions. Conclusions: In adults, expected satiety influences food choice, but only when small equicaloric portions are compared. Larger portions not only promote the consumption of larger meals, but they encourage the adoption of food choice strategies motivated solely by palatability

Portion Size Influences Intake in Samburu Kenyan People Not Exposed to the Western Obesogenic Environment

For people in the modernized food environment, external factors like food variety, palatability, and ubiquitous learned cues for food availability can overcome internal, homeostatic signals to promote excess intake. Portion size is one such external cue; people typically consume more when served more, often without awareness. Though susceptibility to external cues may be attributed to the modernized, cue-saturated environment, there is little research on people living outside that context, or with distinctly different food norms. We studied a sample of Samburu people in rural Kenya who maintain a traditional, semi-nomadic pastoralist lifestyle, eat a very limited diet, and face chronic food insecurity. Participants (12 male, 12 female, aged 20–74, mean BMI = 18.4) attended the study on two days and were provided in counterbalanced order an individual serving bowl containing 1.4 or 2.3 kg of a familiar bean and maize stew. Amount consumed was recorded along with post-meal questions in their dialect about their awareness of intake amount. Data were omitted from two participants who consumed the entire portion in a session. Even though the ‘smaller’ serving was a very large meal, participants consumed 40% more when given the larger serving, despite being unable to reliably identify which day they consumed more food. This result in the Samburu demonstrates the portion size effect is not a by-product of the modern food environment and may represent a more fundamental feature of human dietary psychology