•Blood pressure response to apnoea overlaps in air and in O2.•In O2, apnoeas show a milder response in heart rate and peripheral resistances.•CO2 rise may trigger the pressure increase in phase III.
...To check whether the evolution of alveolar pressures of O2 (PAO2) and CO2 (PACO2) explains the cardiovascular responses to apnoea, eight divers performed resting apnoeas of increasing duration in air and in O2. We measured heart rate (fH), arterial pressure (AP), and peripheral resistances (TPR) beat-by-beat, PAO2 and PACO2 at the end of each apnoea. The three phases of the cardiovascular response to apnoea were observed. In O2, TPR increase (9 ± 4 mmHg min l−1) and fH decrease (-11 ± 8 bpm) were lower than in air (15 ± 5 mmHg min l−1 and -28 ± 13 bpm, respectively). At end of maximal apnoeas in air, PAO2 and PACO2 were 50 ± 9 and 48 ± 5 mmHg, respectively; corresponding values in O2 were 653 ± 8 mmHg and 55 ± 5 mmHg. At end of phase II, PAO2 and PACO2 in air were 90 ± 13 mmHg and 42 ± 4 mmHg respectively; corresponding values in O2 were 669 ± 7 mmHg and 47 ± 6 mmHg. The PACO2 increase may trigger the AP rise in phase III.
The data set for this study comprised 1,488,474 test-day records for milk, fat, and protein yields and fat and protein percentages from 191,012 first-, second-, and third-parity Holstein cows from ...484 farms. Data were collected from 2001 through 2007 and merged with meteorological data from 35 weather stations. A linear model (M1) was used to estimate the effects of the temperature-humidity index (THI) on production traits. Least squares means from M1 were used to detect the THI thresholds for milk production in all parities by using a 2-phase linear regression procedure (M2). A multiple-trait repeatability test-model (M3) was used to estimate variance components for all traits and a dummy regression variable (t) was defined to estimate the production decline caused by heat stress. Additionally, the estimated variance components and M3 were used to estimate traditional and heat-tolerance breeding values (estimated breeding values, EBV) for milk yield and protein percentages at parity 1. An analysis of data (M2) indicated that the daily THI at which milk production started to decline for the 3 parities and traits ranged from 65 to 76. These THI values can be achieved with different temperature/humidity combinations with a range of temperatures from 21 to 36°C and relative humidity values from 5 to 95%. The highest negative effect of THI was observed 4 d before test day over the 3 parities for all traits. The negative effect of THI on production traits indicates that first-parity cows are less sensitive to heat stress than multiparous cows. Over the parities, the general additive genetic variance decreased for protein content and increased for milk yield and fat and protein yield. Additive genetic variance for heat tolerance showed an increase from the first to third parity for milk, protein, and fat yield, and for protein percentage. Genetic correlations between general and heat stress effects were all unfavorable (from −0.24 to −0.56). Three EBV per trait were calculated for each cow and bull (traditional EBV, traditional EBV estimated with the inclusion of THI covariate effect, and heat tolerance EBV) and the rankings of EBV for 283 bulls born after 1985 with at least 50 daughters were compared. When THI was included in the model, the ranking for 17 and 32 bulls changed for milk yield and protein percentage, respectively. The heat tolerance genetic component is not negligible, suggesting that heat tolerance selection should be included in the selection objectives.
Ecological compensation is an effective means to reconcile the imbalance of eco-social development between regions and promote enthusiasm for ecological environmental protection. There is some ...conformity between the theory of ecosystem service flow and ecological compensation, which provides new technical support for the formulation of ecological compensation policy. This study took the Qinghai-Tibet Plateau as the research area, adopted the breaking point model to obtain the spatial characteristics of carbon sequestration flow, and formulated a multilevel ecological compensation policy with Tibet as the design object. The results showed that most of the Qinghai-Tibet Plateau has a carbon sequestration surplus; the central and eastern Qinghai-Tibet Plateau, western Sichuan are successively carbon sequestration supply areas; the Chengdu Plain and Xinjiang were listed as carbon sequestration benefit areas; and the carbon sequestration tended to flow more closely between supply and benefit areas in proximity to each other. Nyingchi, Chamdo, Naqu and Shannan in Tibet need to receive a total ecological compensation of 393.21 million USD, of which 93.71 % is from the national level, 6.02 % is from carbon sequestration benefit areas in other provinces; furthermore, Lhasa and Shigatse in Tibet need to provide the remaining ecological compensation. This study offers innovations for the formulation of ecological compensation policies and provide a new theory for ecological environment management.
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•Spatial characteristics of carbon sequestration flow is obtained.•A multilevel ecological compensation policy of Tibet is formulated.•Most of the Qinghai-Tibet Plateau has a carbon sequestration surplus.•Carbon sequestration tends to flow more closely between supply and benefit areas.•Ecological compensation from three levels accounts for 93.71 %, 6.02 % and 0.27 %.
•Binders modified with rejuvenator have better resistance to low temperature cracking.•PBR 1220 blended with RAP binder showed poor resistance to low-temperature cracking.•Correlations are found ...between colloidal indices and low-temperature performance.
Asphalt binder properties play an important role in the behavior of asphalt concrete pavements at low temperature and should be studied using laboratory tests. This research investigates the relationship between chemical properties and low-temperature performance of asphalt binders at RAP contents of 15%, 30%, 50 and 100% by weight. The asphalt is also modified with a softer binder, oil rejuvenator and polybutadiene rubber (PBR 1220) modified binder. Binder testing includes penetration test, softening point, bending beam rheometer (BBR) and Fraass breaking point. Moreover, saturate, aromatic, resin, and asphaltene (SARA) fractionation is used to study the induced changes in the chemical composition of binders after adding RAP. The results show that binders modified with oil-rejuvenator have better resistance to low temperature cracking in comparison with softer binder and polymer modified binder (PMB), particularly at high percentages of RAP. Using a softer virgin binder also demonstrates improvements in the low-temperature performance of RAP binder. Moreover, PBR 1220 blended with RAP binder showed poor resistance to low-temperature cracking, it means that having a low Tg (for polymer) would not necessarily lead to a good low temperature cracking of the polymer-modified binder. Finally, some promising statistical correlations are found between colloidal indices and low-temperature performance of samples with RAP content.
We have recently introduced a very high order Discontinuous Galerkin (DG) method for the solution of stiff ordinary differential equations (ODEs) and delay differential equations (DDEs). In this ...communication we focus on the detection of breaking points frequently arising in the solution of stiff DDEs. Breaking points are discontinuities appearing in the solution of DDEs and/or in some of its derivatives. Breaking points affect the efficiency of the numerical method by forcing very small time steps in their vicinity. They also locally affect the solution accuracy. We therefore introduce a very simple breaking point detection algorithm in order to further improve the efficiency our DG method.
In this paper, we investigate the dynamics of two mechanical coupled oscillators (MCO) with Parity-Time (PT)-symmetry i.e., one has gain and the other has an equal and opposite amount of loss. In the ...linear case, the eigenmodes and breaking points were determined. In the nonlinear case, the breaking point for soft cubic or quintic potential obtained numerically was also found analytically with perfect agreement. However, instead of the breaking point, for the hard cubic or quintic potential, it is noted a transition toward a regime of periodic or quasi-periodic stable oscillation with energy transfer from the loss oscillator to the gain oscillator. This latter result suggests very important applications within the framework of the optical cavities and waveguides.
•Effects of nonlinear parameters are investigated.•Nonlinearity and initial conditions affect the breaking point.•For hard potentials, oscillatory regime is favoured by nonlinearity.•Even for soft potentials, nonlinearity can boost the oscillatory regime.•The mathematical model studied can be derived from waveguides or optical cavities.
During breath holding after face immersion there develops an urge to breathe. The point that would initiate the termination of the breath hold, the “physiological breaking point,” is thought to be ...primarily due to changes in blood gases. However, we theorized that other factors, such as lung volume, also contributes significantly to terminating breath holds during face immersion. Accordingly, nine naïve subjects (controls) and seven underwater hockey players (divers) voluntarily initiated face immersions in room temperature water at Total Lung Capacity (TLC) and Functional Residual Capacity (FRC) after pre-breathing air, 100% O
2
, 15% O
2
/ 85% N
2
, or 5% CO
2
/ 95% O
2
. Heart rate (HR), arterial blood pressure (BP), end-tidal CO
2
(etCO
2
), and breath hold durations (BHD) were monitored during all face immersions. The decrease in HR and increase in BP were not significantly different at the two lung volumes, although the increase in BP was usually greater at FRC. BHD was significantly longer at TLC (54 ± 2 s) than at FRC (30 ± 2 s). Also, with each pre-breathed gas BHD was always longer at TLC. We found no consistent etCO
2
at which the breath holding terminated. BDHs were significantly longer in divers than in controls. We suggest that during breath holding with face immersion high lung volume acts directly within the brainstem to actively delay the attainment of the physiological breaking point, rather than acting indirectly as a sink to produce a slower build-up of PCO
2
.
The present study aimed to determine whether whole-body fat oxidation and muscle deoxygenation kinetics parameters during exercise were related in individuals with different aerobic fitness levels.
...Eleven cyclists peak oxygen uptake (
): 64.9 ± 3.9 mL⋅kg
⋅min
and 11 active individuals (
: 49.1 ± 7.4 mL⋅kg
⋅min
) performed a maximal incremental cycling test to determine
and a submaximal incremental cycling test to assess whole-body fat oxidation using indirect calorimetry and muscle deoxygenation kinetics of the vastus lateralis (VL) using near-infrared spectroscopy (NIRS). A sinusoidal (SIN) model was used to characterize fat oxidation kinetics and to determine the intensity (Fat
) eliciting maximal fat oxidation (MFO). The muscle deoxygenation response was fitted with a double linear model. The slope of the first parts of the kinetics (
) and the breakpoint (HHb
) were determined.
MFO (
= 0.01) and absolute fat oxidation rates between 20 and 65%
were higher in cyclists than in active participants (
< 0.05), while Fat
occurred at a higher absolute exercise intensity (
= 0.01).
was lower in cyclists (
= 0.02) and HHb
occurred at a higher absolute intensity (
< 0.001) than in active individuals.
was strongly correlated with MFO, Fat
, and HHb
(
= 0.65-0.88,
≤ 0.001). MFO and Fat
were both correlated with HHb
(
= 0.66,
= 0.01 and
= 0.68,
< 0.001, respectively) and tended to be negatively correlated with
(
= -0.41,
= 0.06 for both).
This study showed that whole-body fat oxidation and muscle deoxygenation kinetics were both related to aerobic fitness and that a relationship between the two kinetics exists. Individuals with greater aerobic fitness may have a delayed reliance on glycolytic metabolism at higher exercise intensities because of a longer maintained balance between O
delivery and consumption supporting higher fat oxidation rates.
Changes in motivation have been observed following induction of diet-induced obesity. However, to date, results have been contradictory, some authors reporting an increase in motivation to obtain ...palatable food, but others observing a decrease. Observed differences might be associated with the length of both the evaluation period and exposure to the diet. Therefore, the aim of this study was to evaluate changes in motivation during 20 weeks of exposure to a hypercaloric diet. Performance of the subjects in a progressive ratio schedule was evaluated before and during the exposure to a high-fat, high-sugar choice diet (HFHSc). A decrease in motivation was observed after 2 weeks of diet exposure, low levels of motivation remained throughout 20 weeks. A comparable decrease in motivation took longer (3 weeks) to develop using chow diet in the control group. Overall, our results suggest that, when changes in motivation are being evaluated, long periods of diet exposure made no further contribution, once motivation decreased, it remained low up to 18 weeks. Exposure to a HFHSc diet is a useful animal model of obesity, since it replicates some pathophysiological and psychological features of human obesity such as an increase in fasting glucose levels, body weight and the weight of adipose tissue.
•Two weeks of diet-induced obesity reduced motivation for up to 20 weeks.•Obesity pathopsycophysiological alterations were reproduced by the HFHSc model.•Pre-exposure to reinforcer impacts subject’s performance in the PR schedule.
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