Density-Driven Flows in Evaporating Binary Liquid Droplets.

In the evaporation of microlitre liquid droplets, the accepted view is that surface tension dominates and the effect of gravity is negligible. We report, through the first use of rotating optical coherence tomography, that a change in the flow pattern and speed occurs when evaporating binary liquid droplets are tilted, conclusively showing that gravitational effects dominate the flow. We use gas chromatography to show that these flows are solutal in nature, and we establish a flow phase diagram demonstrating the conditions under which different flow mechanisms occur.

Cryptic male choice: experimental evidence of sperm sex ratio and seminal fluid adjustment in relation to coital rate.

The differential allocation hypothesis suggests that a mother should adjust the sex of offspring in relation to her mate's attractiveness, thereby increasing future reproductive fitness when her sons inherit the attractive traits. More attractive males have been shown to sire more sons, but it is possible that the sex ratio skew could be a result of paternal rather than maternal manipulation, which would be a more parsimonious explanation. We manipulated coital rate (an indicator of attractiveness) in laboratory mice and showed that males that mate more often have higher levels of glucose in their semen despite lower blood glucose levels. Since peri-conceptual glucose levels in utero increase male conceptus survival, this could result in male-biased sex ratios. The males that mated most also had more remaining X-chromosome-bearing-spermatozoa, suggesting depletion of Y-chromosome-bearing-spermatozoa during mating. We hypothesise that males may alter both seminal fluids and X:Y ratios in an ejaculate to influence subsequent sex ratios. Our results further support a paternal role in sex allocation.

Brain and Cardiorespiratory Responses to Exercise in Hot and Thermoneutral Conditions.

The aim of this study was to test whether or not concurrent evaluations of brain (electroencephalography [EEG]) and cardiorespiratory responses to exercise are influenced by environmental conditions. 10 adult male participants performed a standardized incremental exercise test to exhaustion on a cycle ergometer in an environment controlled laboratory on 2 separate occasions, in a randomized order; one in a hot condition (34.5°C) and one in a thermoneutral condition (20°C). EEG, heart rate and expired air were collected throughout. EEG data were decontaminated for artefacts, log-transformed and expressed as aggregated alpha and beta power responses across electrodes reflecting the frontal cortex of the brain. Performance outcomes showed there was no difference in V˙O2 peak across hot (42.5 ml/kg/min) and neutral (42.8 ml/kg/min) conditions, although ventilatory threshold (VT) occurred at a lower threshold (68%) in hot compared to neutral condition (74%) (p<0.05). EEG alpha and beta wave responses both demonstrated significant increases from baseline to VT (p<0.01). EEG beta-band activity was significantly elevated in the heat compared to the neutral condition. In conclusion, elevated EEG beta-band activity in response to incremental exercise in the heat suggests that beta-band activation and cortical awareness increases as exercise becomes increasingly intense.

Utilization of a high-throughput shoot imaging system to examine the dynamic phenotypic responses of a C4 cereal crop plant to nitrogen and water deficiency over time.

The use of high-throughput phenotyping systems and non-destructive imaging is widely regarded as a key technology allowing scientists and breeders to develop crops with the ability to perform well under diverse environmental conditions. However, many of these phenotyping studies have been optimized using the model plant Arabidopsis thaliana. In this study, The Plant Accelerator(®) at The University of Adelaide, Australia, was used to investigate the growth and phenotypic response of the important cereal crop, Sorghum bicolor L. Moench and related hybrids to water-limited conditions and different levels of fertilizer. Imaging in different spectral ranges was used to monitor plant composition, chlorophyll, and moisture content. Phenotypic image analysis accurately measured plant biomass. The data set obtained enabled the responses of the different sorghum varieties to the experimental treatments to be differentiated and modelled. Plant architectural instead of architecture elements were determined using imaging and found to correlate with an improved tolerance to stress, for example diurnal leaf curling and leaf area index. Analysis of colour images revealed that leaf 'greenness' correlated with foliar nitrogen and chlorophyll, while near infrared reflectance (NIR) analysis was a good predictor of water content and leaf thickness, and correlated with plant moisture content. It is shown that imaging sorghum using a high-throughput system can accurately identify and differentiate between growth and specific phenotypic traits. R scripts for robust, parsimonious models are provided to allow other users of phenomic imaging systems to extract useful data readily, and thus relieve a bottleneck in phenotypic screening of multiple genotypes of key crop plants.

Effect of enhanced whole-milk feeding in calves on subsequent first-lactation performance.

The objective of this study was to determine the effect of enhanced whole-milk (WM) feeding systems in calves from birth to 8wk of age on subsequent first-lactation performance. The experiment was conducted as a completely randomized design consisting of 2 treatment groups. At birth, 152 Holstein heifer calves were randomly assigned to 1 of 2 treatments: (i) 4L of WM/d or (ii) 8L of WM/d. The calves were bucket fed 2 or 4L of WM twice daily at 0700 and 1600h. Each calf was housed individually in temperature-controlled nurseries and had ad libitum access to water and textured calf starter daily. Calves consumed greater volumes of textured calf starter when fed 4 versus 8L of WM/d. Water intakes mirrored starter intakes, leading to greater water consumption at weaning. Calves reared on 8L of WM/d were heavier at d 56 than calves reared on 4L of WM/d. The average daily gain of the calves offered 8L of WM/d from d 0 to 56 was greater than that of calves offered 4L of WM/d. Structural measurements were significantly greater for calves that consumed 8L of WM/d. The differences observed in withers height and live BW due to WM feeding level were not apparent by 3 and 12mo of age, respectively. Rumen pH was higher in calves that consumed 8L of WM/d than in calves that consumed 4L of WM/d. Whole-milk feeding level did not affect age at first calving or milk-production parameters. These results suggest that enhanced WM feeding improved growth performance until 3mo of age. However, first-lactation results indicated no lactation-performance benefits of increased nutrition and growth performance during the milk-fed period in dairy calves.

Utility of field-based techniques to assess Indigenous Australians' functional fitness and sedentary time.

OBJECTIVE: To examine the utility of field-based techniques to assess functional exercise capacity and sedentary time in Indigenous and non-Indigenous regional Australian adults. STUDY DESIGN: Observational, analytic cohort study. METHODS: Ninety six adults residing in regional and remote Australian communities participated in this study (Indigenous n = 61 and non-Indigenous Australians n = 35). Participants undertook a field-based test of functional exercise capacity (6 min walk test; 6 MWT) and wore an accelerometer during waking hours for seven days, provided self-report data on physical activity and sedentary time and rated experiences in regard to the ease of complying with study protocols. RESULTS: There were high levels of compliance in this study (Indigenous: 91% and non-Indigenous: 97%). Functional exercise capacity was lower in Indigenous Australians (P < 0.001), and independently associated with advancing age, higher BMI, and indigeneity, with 45% of variability in the 6 MWT distance explained by these factors. The relationship between accelerometer and self-report measures of sedentary behaviour was significant (P < 0.001) but only explained 17% of the total variation. CONCLUSIONS: This study demonstrated very good compliance for the methods utilised and is the first to report reduced functional exercise capacity in Indigenous people. IMPLICATIONS: The field-based techniques from this study demonstrate good utility for larger scale implementation in regional Indigenous populations.

Respiratory muscle training extends exercise tolerance without concomitant change to peak oxygen uptake: physiological, performance and perceptual responses derived from the same incremental exercise test.

BACKGROUND AND OBJECTIVE: There is conjecture over the efficacy of respiratory muscle training (RMT). The aim of this study was to establish whether or not exercise tolerance, physical performance and effort perceptions are influenced by RMT. METHODS: Thirty-six healthy males (age 24 ± 4) agreed to participate (experimental group (EXP) n = 18, control (CON) n = 18). RMT was performed using an inspiratory pressure-threshold training device at either 55% (EXP) or 10% (CON) of maximal inspiratory effort. Measurements of spirometry and maximal static inspiratory mouth pressure were taken before and after 4 weeks of RMT in addition to an incremental test to volitional exhaustion for the determination of: (i) V˙O(2) peak; (ii) maximal velocity at volitional exhaustion (vV˙O(2) peak)); (iii) time to volitional exhaustion; and (iv) effort perceptions. RESULTS: There were no differences in spirometry, but mean maximal static inspiratory mouth pressure increased significantly in EXP (P < 0.01). V˙O(2) peak was unchanged following the 4-week intervention for both EXP and CON, although the proportion of EXP attaining the criteria for a V˙O(2) plateau significantly increased (P < 0.05). Both time to volitional exhaustion (P < 0.05) and vV˙O(2) peak were significantly improved for EXP (P < 0.05), while effort perceptions were reduced (P < 0.05). CONCLUSIONS: EXP tolerated higher running velocities during incremental exercise and demonstrated a significant flattening (plateau) of V˙O(2) after training. This suggests that RMT may promote an improved performance outcome vV˙O(2) peak probably as a result of blunted afferent sensations reducing the perceived discomfort of exercise at high ventilatory loads.

Physiological responses to self-paced exercise: effort-matched comparisons across running and rowing modalities.

AIM: The purpose of this study was to examine whether or not physiological responses to self-pacing are similar across different exercise modalities where the rating of perceived exertion (RPE) is matched. METHODS: Ten recreationally active adult male subjects completed baseline tests of peak oxygen uptake (.VO2) and subsequently on two separate occasions performed 20-min exercise bouts at RPE 15 (Hard) on both a motorized treadmill and a rowing ergometer. RESULTS: Mean relative work intensity (% of baseline peak (.VO2) for treadmill running was significantly higher than for rowing (86.1% vs. 83.7%) (P<0.05). Mean heart rates (174.7±5.9 vs. 165.5±6.6 b∙min-1) and pre- to post-bout changes in blood lactate concentration (4.0±0.8 vs. 3.3±1.2 mmol/L) were also greater in the running trial than rowing (P<0.05). Baseline peak (.VO2 was positively correlated between modalities (r=0.63; P<0.05) as were the main trial mean (.VO2 (r=0.73; P<0.05) and heart rate (r=0.67; P<0.05) from the 20-min bouts. CONCLUSION: The elevated relative exercise intensity and physiological responses to motorized treadmill running suggests greater work outputs can be accomplished in this modality for the same perceived effort compared to rowing among recreationally active participants.

Sport-specific fitness testing differentiates professional from amateur soccer players where VO2max and VO2 kinetics do not.

AIM: The purpose of this study was to identify if sport-specific and cardiopulmonary exercise testing differentiated professional from amateur soccer players. METHODS: Thirty six men comprising 18 professional (mean±s: age 23.2±2.4 years) and 18 amateur (mean±SD: age 21.1±1.6 years) soccer players participated and performed four tests on separate occasions: 1) a graded exercise test to determine VO2max; 2) four exercise transients from walking to 80%Δ for the determination of VO2 kinetics; 3) the Yo-Yo Intermittent Recovery Test level 2 (Yo-Yo IR2) and 4) a repeated sprint test (RST). RESULTS: The players did not differ in VO2max (professional 56.5±2.9 mL.kg-1.min-1; amateur 55.7±3.5 mL.kg-1.min-1: P=0.484) or VO2 kinetic fundamental measures (τ1 onset, professional 24.5±3.2 s; amateur 24.0±1.8 s: τ1 cessation, professional 28.7±2.8 s; amateur 29.3±3.5 s: P=0.923). However, the amateurs were outperformed in the Yo-Yo IR2 (Professional 966±153 m; Amateur 840±156 m) (P=0.034) and RST (best time, professional 6.46±0.27 s; amateur 6.84±0.24 s, P=0.012). CONCLUSION: Performance indices derived from field-based sport-specific performance tests identified significant differences between professional and amateur players (P<0.05). However, neither tests of VO2 kinetics nor VO2max differentiated between groups, suggesting laboratory tests of cardiorespiratory parameters are probably less consequential to soccer than sport-specific field-based observations.

Cancer blues? A promising judgment bias task indicates pessimism in nude mice with tumors.

In humans, affective states can bias responses to ambiguous information: a phenomenon termed judgment bias (JB). Judgment biases have great potential for assessing affective states in animals, in both animal welfare and biomedical research. New animal JB tasks require construct validation, but for laboratory mice (Mus musculus), the most common research vertebrate, a valid JB task has proved elusive. Here (Experiment 1), we demonstrate construct validity for a novel mouse JB test: an olfactory Go/Go task in which subjects dig for high- or low-value food rewards. In C57BL/6 and Balb/c mice faced with ambiguous cues, latencies to dig were sensitive to high/low welfare housing: environmentally-enriched animals responded with relative 'optimism' through shorter latencies. Illustrating the versatility of this validated JB task across different fields of research, it further allowed us to test hypotheses about the mood-altering effects of cancer in male and female nude mice (Experiment 2). Males, although not females, treated ambiguous cues as intermediate; and males bearing subcutaneous lung adenocarcinomas also responded more pessimistically to these than did healthy controls. To our knowledge, this is the first evidence of a valid mouse JB task, and the first demonstration of pessimism in tumor-bearing animals. This task still needs to be refined to improve its sensitivity. However, it has great potential for investigating mouse welfare, the links between affective state and disease, depression-like states in animals, and hypotheses regarding the neurobiological mechanisms that underlie affect-mediated biases in judgment.

Photobehavior of merocyanine 540 bound to human serum albumin.

The photobehavior of merocyanine 540 (MC) was studied in homogeneous media (ethanol, buffer and glycerol), and in microheterogenous systems (Triton X-100 micelles and in the presence of human serum albumin) using stationary and time-resolved techniques. Merocyanine 540 in aqueous solution mostly forms aggregates, which in the presence of Triton X-100 or HSA are disaggregated. The extent of binding to HSA and its characteristics were estimated from dye absorption and fluorescence changes following protein addition; the Trp-214 fluorescence quenching was also employed to assess the extent of dye association, and physical separation was employed to evaluate the dye's apparent association constant. These results showed that dye adsorption on HSA takes place at both main protein-binding sites (I and II). This adsorption leads to dye monomerization, changing its photobehavior remarkably, with a noticeable increase in fluorescence and triplet lifetimes. These slower decays can be ascribed to a reduction of the dye photoisomerization rate. In addition, the adsorption of the dye partially protects it from the oxygen present in solution, thus reducing the apparent dye triplet-quenching rate constant. However, singlet oxygen and MC triplet quantum yields remain very low in all the systems tested. Finally, we found that the photoconsumption of merocyanine bound to HSA takes place predominantly by a type I mechanism, being more than seven times more efficient than that taking place in ethanol.

Architecture of RNA polymerase II and implications for the transcription mechanism.

A backbone model of a 10-subunit yeast RNA polymerase II has been derived from x-ray diffraction data extending to 3 angstroms resolution. All 10 subunits exhibit a high degree of identity with the corresponding human proteins, and 9 of the 10 subunits are conserved among the three eukaryotic RNA polymerases I, II, and III. Notable features of the model include a pair of jaws, formed by subunits Rpb1, Rpb5, and Rpb9, that appear to grip DNA downstream of the active center. A clamp on the DNA nearer the active center, formed by Rpb1, Rpb2, and Rpb6, may be locked in the closed position by RNA, accounting for the great stability of transcribing complexes. A pore in the protein complex beneath the active center may allow entry of substrates for polymerization and exit of the transcript during proofreading and passage through pause sites in the DNA.

Self-paced exercise is less physically challenging than enforced constant pace exercise of the same intensity: influence of complex central metabolic control.

OBJECTIVE: To examine whether self-pacing reduces the physiological challenge of performing 5000 m rowing ergometry exercise in comparison with a matched-intensity exercise condition in which a constant effort pacing strategy is enforced. METHODS: Nine healthy well-trained male participants volunteered to participate in three 5000 m rowing conditions (two submaximal and one maximal conditions) in an individualised order. In the submaximal conditions, participants were required to (1) perform 5000 m at a constant rating of perceived exertion (RPE 15-Hard) (SubRPE) or (2) perform 5000 m at an enforced constant pace equivalent to the mean power output (PO) of the SubRPE condition (SubEXT). A maximal condition (MaxTT) was included to disguise the purpose of the study and to facilitate an element of randomisation in the test sequence. Dynamic intratest responses were assessed every 30 s: PO, VO2, iEMG, core (Tc) and skin temperatures (Tsk). RESULTS: There was no difference between performance times of the two submaximal trials. The mean PO represented 83.83 (SD 8.88)% (SubRPE) and 83.40 (8.84)% (SubEXT) of the mean MaxTT power output. Tc (SubRPE:38.46 (0.23) degrees C, SubEXT:38.72 (0.36) degrees C; p<0.01), post-test BLa (SubRPE:5.24 (2.18), SubEXT:6.19 (2.51) mmol/l; p<0.05) and iEMG (p<0.05) were significantly elevated in SubEXT compared with SubRPE. There were no differences in the dynamics of HR or VO2 between SubEXT and SubRPE. The intratest stroke-to-stroke variability of power output was significantly greater in the SubRPE condition compared with SubEXT (p<0.01). CONCLUSIONS: Enforced constant paced exercise presents a significantly greater physiological challenge than self-paced exercise. The ability to dynamically self-pace effort via manipulations of power output during exercise is an important behavioural response to homeostatic challenges and thus forms an integral part of a complex central regulatory process.

Maternal effects obscure condition-dependent sex allocation in changing environments.

Climate change increases environmental fluctuations which thereby impact population demography. Species with temperature-dependent sex determination may experience more extreme sex ratio skews, but this has not been considered in species with chromosomally determined sex. However, anticipatory maternal effects cause lifelong physiological changes impacting sex ratios. Here we show, in mice, that more sons were born to mothers in good condition when their breeding environment matched their gestational environment, consistent with theoretical predictions, but mothers in mismatched environments have no condition-sex ratio relationship. Thus, the predicted effect of condition on sex ratio was obscured by maternal effects when the environment changed. This may explain extreme sex ratio skews in reintroduced or translocated populations, and sex ratio skews may become more common and less predictable with accelerating environmental change.

Concurrent inspiratory muscle and cardiovascular training differentially improves both perceptions of effort and 5000 m running performance compared with cardiovascular training alone.

OBJECTIVE: To examine whether inspiratory muscle training (IMT) is a useful additional technique with which to augment cardiovascular exercise training adaptations. METHODS: 16 healthy untrained males agreed to participate in the study and were randomly assigned to training (TRA; n = 8) and placebo (PLA; n = 8) groups. Pre- and post-training measurements of spirometry and maximal inspiratory mouth pressure (MIP) were taken in addition to i) maximal aerobic power (VO(2max)) and ii) 5000 m run time-trial. All subjects completed the same 4 week cardiovascular training programme which consisted of three running sessions (CV1: 5 x 1000 m, CV2: 3 x 1600 m, SP1: 20 min run) in each of the 4 weeks. IMT was performed daily by both groups using an inspiratory muscle trainer (POWERbreathe). TRA completed 30 maximal inspirations while PLA inspired 30 times against a negligible resistance. RESULTS: Mean MIP increased significantly in both groups (TRA: 14.5 (SD 6.8)% change, PLA: 7.8 (7.4)% change) from pre- to post-training (p<0.01) but was not significantly related to changes in running performance. Mean CV1 training-repetition runs improved similarly in both groups, but RPE evaluations were significantly reduced in TRA (15.7 (0.7)) compared with PLA (16.6 (0.8)) at week 4 (p<0.05). Pre- to post-training changes in VO(2max) were well-matched between both TRA (+2.1 (2.3)%) and PLA (+1.3 (2.4)%) while post-intervention 5000 m performance was significantly augmented in TRA compared with PLA (TRA: 4.3 (1.6)%, PLA: 2.2 (1.9)%, p<0.05). CONCLUSIONS: The addition of IMT to a cardiovascular training programme augments 5000 m running performance but exerts no additional influence over VO(2max) compared with a cardiovascular-training group. This is probably due to IMT-induced reduction in perceived effort at high ventilatory rates, which is of greater consequence to longer duration time-trial performances than incremental tests of VO(2max).

Myelin-associated glycoprotein, a cell adhesion molecule of oligodendrocytes, is phosphorylated in brain.

Myelin-associated glycoprotein (MAG) has been implicated in the mediation of interactions between oligodendrocytes and neurons during the development of the myelin sheath. Here we show that MAG is phosphorylated in intact myelinating mouse brain primarily at serine residues and to a lesser extent at threonine and tyrosine residues. In vivo, only the larger of the two developmentally regulated MAG isoforms is phosphorylated. MAG can be phosphorylated at tyrosine by the v-fps and v-src protein-tyrosine kinases in vitro and by a kinase endogenous to myelin membrane preparations. MAG phosphorylated in myelin membranes in vitro also contains phosphoserine and phosphothreonine. These observations suggest that phosphorylation of MAG is physiologically significant in regulating oligodendrocyte-neuron interactions.

Epitaxial growth of protein crystals from two-dimensional crystals on lipid layers.

Two-dimensional crystals of proteins formed on lipid layers effectively nucleate the epitaxial growth of three-dimensional protein crystals. Crystals suitable for X-ray crystallography can be grown in this way more rapidly, and using substantially lower concentrations of protein and precipitants, than when using conventional methods.

Origin DNA-binding proteins.

The first step in DNA replication involves the recognition of origin DNA sequences by origin-binding proteins. The three-dimensional structures of three different origin DNA-binding proteins have recently been solved. These proteins form a structural class distinct from other DNA-binding proteins. One of the origin-binding proteins, Epstein-Barr virus nuclear antigen 1, most likely has two modes of DNA binding; the sequential use of these modes may be important for the initiation of DNA replication.

Effects of photoperiod and glucose-supplemented drinking water on the performance of dairy calves.

Long-day photoperiods (LDPP) have been shown to increase milk production in lactating dairy cattle. The objective of this study was to determine the effects of supplemental light and glucose-supplemented drinking water on starter dry matter intake (DMI), water intake, serum and rumen metabolites, and growth performance of calves from birth to 8 wk of age. The experiment was conducted as a completely randomized design with a 2 x 2 factorial arrangement of treatments. The calves were assigned at birth to 1 of 4 treatments: 1) 10 h of light, 14 h of dark (short-day photoperiods; SDPP), ad libitum intake of water, and no glucose supplementation; 2) 10 h of light, 14 h of dark, and ad libitum intake of water supplemented with 50 g of glucose/L; 3) 18 h of light, 6 h of dark (LDPP), and ad libitum intake of water, and no glucose supplementation; and 4) 18 h of light, 6 h of dark, and ad libitum intake of water supplemented with 50 g of glucose/L. Fluorescent lights were used to provide lighting at an intensity of approximately 600 lx at the eye level of calves. The calves were bucket-fed 2 L of whole milk offered twice daily at 0700 and 1600 h and had a free access to a textured calf starter. The calves on LDPP were heavier at d 56 than SDPP calves regardless of level of glucose supplementation. The average daily gain of the calves on LDPP from d 29 to 42 and from d 43 to 56 was greater than for SDPP calves regardless of the level of glucose supplementation. The greater average daily gain of LDPP calves from d 29 to 56 coincided with the greater calf starter DMI of these calves. Body widths through hooks were highly (r = 0.72) correlated with body weights, which in turn were related to calf starter DMI. Calves on LDPP had greater ruminal osmolarity and greater concentrations of acetate, propionate, butyrate, and total volatile fatty acids than SDPP calves regardless of the level of glucose supplementation. Calves on LDPP had lower Ca:P ratio than the SDPP calves regardless of level of glucose supplementation. The concentrations of serum glucose and sodium for the glucose-supplemented calves were greater than for nonsupplemented calves regardless of lighting regimen. These results suggest that LDPP encouraged greater consumption of calf starter, which stimulated faster rumen development in the LDPP calves as evidenced by greater volatile fatty acid concentrations.

Retracted and replaced: Sodium cromoglicate: an ineffective drug or meta-analysis misused?

The following article from Pharmaceutical Statistics, Sodium cromoglicate: an ineffective drug or meta-analysis misused? by M. T. Stevens, A. M. Edwards, J. B. L. Howell published online on 15 March 2007 in Wiley InterScience (www.interscience.wiley.com), has been retracted by agreement between the author, the journal Editor in Chief, Steven Julious, and John Wiley & Sons, Ltd. The retraction has been agreed because the article is not yet ready for publication and an early version without revisions was published in error. Replacement article pending. Copyright (c) 2007 John Wiley & Sons, Ltd.