27 research outputs found
Energy intake and appetite responses following manipulation of fluid balance and intake
Fluid intake and regulation are implicated in the control of energy balance and appetite. The studies in this thesis have examined the effects of fluid manipulation on appetite and energy intake. Fifty-eight young, predominantly Caucasian males were recruited to five studies. The age, height and body mass of the subjects were: 24.9 ± 3.8 y, 1.79 ± 0.1 m, 80.1 ± 14.8 kg (mean ± SD) respectively.
In Chapter 3, 13 h of hypohydration after exercise in the heat did not influence energy intake at an ad-libitum buffet meal (P=0.436) compared to a euhydrated trial, although greater thirst (P<0.001) and lower fullness (P<0.01) was reported in the hypohydration trial.
Chapter 4 demonstrated that there was no difference in energy intake or appetite after 24 h of hypohydration either with or without fluid during a semi-solid ad-libitum breakfast. Thirst and fluid intake were greater during the hypohydrated with fluid (HYPO-F; 618 (251) mL) than the euhydrated with fluid (EU-F; 400 (247) mL) trials (P<0.01).
Chapter 5 and 6 showed that a bolus of water (500 mL) immediately before an ad-libitum porridge breakfast reduced energy intake in both healthy and overweight and obese subjects (P<0.001). The water preload increased fullness and decreased hunger compared to pre-trial in both studies (P<0.001).
In Chapter 7, 75 minutes before an ad-libitum lunch a post-exercise milk (MILK) based drink reduced energy intake (6746 (2035) kJ) compared to an isoenergetic flavoured carbohydrate (CHO) and water based drink (7762 (1921) kJ; 7672 (2005) kJ) (P<0.05).
This thesis has shown that when subjects are hypohydrated, either after exercise or after 24 h of fluid restriction energy intake is not different at an ad-libitum meal. However, there is an increased thirst and subsequent fluid intake before an ad-libitum meal (chapter 3 and 4). This effect was more acutely displayed when a bolus of water was provided immediately before an ad-libitum breakfast meal and subsequently decreased energy intake in both normal and overweight/ obese subjects (chapter 5 and 6). The possible mechanism for this was gastric fill and distension creating satiety before a meal. Chapter 7 has showed that when subjects consume isoenergetic drinks with different energy densities (milk vs CHO and water), before an ad-libitum lunch, energy intake was decreased when milk was consumed. Milk having an increased energy density due to larger protein fractions (casein) may further explain the decrease in energy intake found in chapters 5 and 6 by a similar mechanism. Therefore, gastric fill before a meal decreases ad-libitum energy intake by either the intake of water immediately before a meal or by milk as a more delayed response (75 min). The hydration status however, did not affect energy intake directly in our finding, although it did affect subsequent fluid ingestion, which may have affected findings in chapters 3 and 4
Quantum dynamics in ultra-cold atomic physics
We review recent developments in the theory of quantum dynamics in ultra-cold
atomic physics, including exact techniques, but focusing on methods based on
phase-space mappings that are appli- cable when the complexity becomes
exponentially large. These phase-space representations include the truncated
Wigner, positive-P and general Gaussian operator representations which can
treat both bosons and fermions. These phase-space methods include both
traditional approaches using a phase-space of classical dimension, and more
recent methods that use a non-classical phase-space of increased
dimensionality. Examples used include quantum EPR entanglement of a four-mode
BEC, time-reversal tests of dephasing in single-mode traps, BEC quantum
collisions with up to 106 modes and 105 interacting particles, quantum
interferometry in a multi-mode trap with nonlinear absorp- tion, and the theory
of quantum entropy in phase-space. We also treat the approach of variational
optimization of the sampling error, giving an elementary example of a nonlinear
oscillator
Non-destructive, dynamic detectors for Bose-Einstein condensates
We propose and analyze a series of non-destructive, dynamic detectors for
Bose-Einstein condensates based on photo-detectors operating at the shot noise
limit. These detectors are compatible with real time feedback to the
condensate. The signal to noise ratio of different detection schemes are
compared subject to the constraint of minimal heating due to photon absorption
and spontaneous emission. This constraint leads to different optimal operating
points for interference-based schemes. We find the somewhat counter-intuitive
result that without the presence of a cavity, interferometry causes as much
destruction as absorption for optically thin clouds. For optically thick
clouds, cavity-free interferometry is superior to absorption, but it still
cannot be made arbitrarily non-destructive . We propose a cavity-based
measurement of atomic density which can in principle be made arbitrarily
non-destructive for a given signal to noise ratio
Immediate pre-meal water ingestion decreases voluntary food intake in lean young males
Purpose: Consuming 375-500 ml of water 30 min before a meal has been shown to reduce energy intake in older, but not younger adults. This study investigated the effects of ingesting a water preload immediately pre-meal (<1 min before eating) on within-meal ad-libitum energy intake in non-obese young males.
Methods: Fourteen healthy males (mean (SD) age 27 (3) y, Height 1.83 (0.05) m, body weight 80.47 (9.89) kg, body fat 17.5 (4.0) %, body mass index 24.0 (2.5) kg/m2) completed a familiarisation trial and two experimental trials in randomised counterbalanced order. Subjects arrived at the laboratory overnight fasted and consumed an ad-libitum porridge breakfast. Immediately prior to the meal, subjects consumed either a 568 ml (1 pint) water preload (preload trial) or no preload (control trial). Visual analogue scale questionnaires to assess hunger, fullness and satisfaction were completed before and after the meal in both trials, as well as after the water preload.
Results: Ad-libitum energy intake was greater (P<0.001) during control (2551 (562) kJ) than preload (1967 (454) kJ). Ad-libitum water intake was also greater (P<0.001) during control (318 (226-975) ml) than preload (116 (0-581) ml). The water preload increased fullness and satisfaction and decreased hunger compared to pre-trial (P<0.001) and the control trial (P<0.001).
Conclusion: This study demonstrates that consumption of a 568 ml water preload immediately before a meal reduces energy intake in non-obese young males. This might therefore be an effective strategy to suppress energy intake in this population and possibly assist with weight management
Double-well magnetic trap for Bose-Einstein condensates
We present a magnetic trapping scheme for neutral atoms based on a hybrid of
Ioffe-Pritchard and Time-averaged Orbiting Potential traps. The resulting
double-well magnetic potential has readily controllable barrier height and well
separation. This offers a new tool for studying the behavior of Bose
condensates in double-well potentials, including atom interferometry and
Josephson tunneling. We formulate a description for the potential of this
magnetic trap and discuss practical issues such as loading with atoms,
evaporative cooling and manipulating the potential.Comment: 7 pages, 6 figures, Revtex
MIRTFnet: Analysis of miRNA Regulated Transcription Factors
Several expression datasets of miRNA transfection experiments are available to analyze the regulatory mechanisms downstream of miRNA effects. The miRNA induced regulatory effects can be propagated via transcription factors (TFs). We propose the method MIRTFnet to identify miRNA controlled TFs as active regulators if their downstream target genes are differentially expressed
Global urban environmental change drives adaptation in white clover
Urbanization transforms environments in ways that alter biological evolution. We examined whether urban environmental change drives parallel evolution by sampling 110,019 white clover plants from 6169 populations in 160 cities globally. Plants were assayed for a Mendelian antiherbivore defense that also affects tolerance to abiotic stressors. Urban-rural gradients were associated with the evolution of clines in defense in 47% of cities throughout the world. Variation in the strength of clines was explained by environmental changes in drought stress and vegetation cover that varied among cities. Sequencing 2074 genomes from 26 cities revealed that the evolution of urban-rural clines was best explained by adaptive evolution, but the degree of parallel adaptation varied among cities. Our results demonstrate that urbanization leads to adaptation at a global scale
Effect of hydration status and fluid availability on ad-libitum energy intake of a semi-solid breakfast
This study investigated the effects of hydration status and fluid availability on appetite and energy intake. Sixteen males completed four 24 h trials, visiting the laboratory overnight fasted on two consecutive days. Standardised foods were provided during the 24 h and on day two an ad-libitum semi-solid porridge breakfast was provided. Water intake during the 24 h (0 or 40 mL·kg-1) and fluid provision during the ad-libitum breakfast were manipulated so subjects were euhydrated with (EU-F) and without fluid (EU-NF) available at breakfast; and hypohydrated with (HYPO-F) and without fluid (HYPO-NF) available at breakfast. Blood samples (0 and 24 h), urine samples (0-24 h) and subjective responses (0, 24 and 24.5 h) were collected. HYPO trials decreased body mass by ~1.8%. Serum and urine osmolality increased and plasma volume decreased during HYPO trials (P < 0.001). Total urine output was greater during EU than HYPO trials (P < 0.001). Ad-libitum energy intake was not different between trials: 2658 (938) kJ (EU-F), 2353 (643) kJ (EU-NF), 2295 (529) kJ (HYPO-F), 2414 (954) kJ (HYPO-NF), (P = 0.131). Fluid intake was ~200 mL greater during HYPO-F than EU-F (P < 0.01). There was an interaction effect for thirst (P < 0.001), but not hunger or fullness. These results demonstrate that mild hypohydration produced by inadequate fluid intake and fluid availability during eating does not influence ad-libitum energy intake of a semi-solid breakfast, at least in healthy young males
Finding mesopelagic prey in a changing Southern Ocean
International audienceMesopelagic fish and squid occupy ocean depths extending below the photic zone and their verticalmigrations represent a massive pathway moving energy and carbon through the water column.Their spatio-temporal distribution is however, difficult to map across remote regions particularly thevast Southern Ocean. This represents a key gap in understanding biogeochemical processes, marineecosystem structure, and how changing ocean conditions will affect marine predators, which dependupon mesopelagic prey. We infer mesopelagic prey vertical distribution and relative abundance inthe Indian sector of the Southern Ocean (20° to 130°E) with a novel approach using predator-derivedindices. Fourteen years of southern elephant seal tracking and dive data, from the open ocean betweenthe Antarctic Polar Front and the southern Antarctic Circumpolar Current front, clearly show that thevertical distribution of mesopelagic prey is influenced by the physical hydrographic processes thatstructure their habitat. Mesopelagic prey have a more restricted vertical migration and higher relativeabundance closer to the surface where Circumpolar Deep Water rises to shallower depths. Combiningthese observations with a future projection of Southern Ocean conditions we show that changes in thecoupling of surface and deep waters will potentially redistribute mesopelagic prey. These changes aresmall overall, but show important spatial variability: prey will increase in relative abundance to the eastof the Kerguelen Plateau but decrease to the west. The consequences for deep-diving specialists such aselephant seals and whales over this time scale will likely be minor, but the changes in mesoscale verticalenergy flow have implications for predators that forage within the mesopelagic zone as well as thebroader pelagic ecosystem