共查询到20条相似文献,搜索用时 15 毫秒
1.
A method based on the fluorescence probe 8-hydroxypyrene-1,3,6-trisulfonic acid for in situ measurement of pH in partly frozen
aqueous solutions was developed using multifrequency, phase-modulated fluorescence spectroscopy inherently correcting for
light scattering. The probe was determined to have pK
a = 7.72 ± 0.03 at 25.0 °C extrapolated to zero ionic strength with as derived from temperature dependence (5 to 25 °C investigated). Ionic strength dependence of pK
a determined experimentally was described using Debye–Hückel formalism for ionic strength up to 3 M. Temperature and ionic
strength dependence were combined to yield for determination of pH at subzero temperatures with α experimentally determined from the ratio between fluorescence intensity after excitation at 454 and 415 nm, α = FI(454 nm)/2.5·FI(415 nm). Fluorescence could be described as a decay of a single excited state with a fluorescence life
time of 5.40 ± 0.05 ns at 25 °C, and excited state acid–base equilibration was shown not to interfere with the pH measurement.
Using the method, pH of a 0.25 M phosphate buffer with pH = 6.8 at 25 °C was shown to decrease gradually to pH = 4.2 in the
ice slurry at −13 °C. 相似文献
2.
de Magalhães Erismann N Caruso Machado E Sant' Anna Tucci ML 《Photosynthesis research》2008,96(2):163-172
Photosynthetic limitations under moderate water deficit were evaluated in ‘Valência’ orange trees grafted on three different
rootstocks, in pots. Net CO2 assimilation rate (A
N), stomatal conductance (g
s), and photosystem II (PS II) operating efficiency (
) in response to changing intercellular CO2 partial pressure (C
i) were analyzed under controlled conditions. Drought decreased A
N and g
s, whereas remained unchanged. This resulted in a higher ratio between electron transport rate (ETR) and gross CO2 assimilation rate (A
G). Since the comparison of A
N–C
i gas exchange curves can lead to incorrect conclusions, a normalization of C
i values () of stressed leaves was applied. Then, the relationship established for irrigated trees between the ETR/A
G ratio and C
i was used to estimate the from ETR/A
G ratios measured under water stress. The response of A
N to suggests that the CO2 diffusional restriction is the main factor that limits photosynthesis in orange leaves under moderate water deficit. 相似文献
3.
Human thermal comfort assessments pertaining to exercise while in outdoor environments can improve urban and recreational
planning. The current study applied a simple four-segment skin temperature approach to the COMFA (COMfort FormulA) outdoor
energy balance model. Comparative results of measured mean skin temperature (
[`(T)]\nolimitsMsk \mathop{{\bar{T}}}\nolimits_{{Msk}} ) with predicted
[`(T)]\nolimitssk \mathop{{\bar{T}}}\nolimits_{{sk}} indicate that the model accurately predicted
[`(T)]\nolimitssk \mathop{{\bar{T}}}\nolimits_{{sk}} , showing significantly strong agreement (r = 0.859, P < 0.01) during outdoor exercise (cycling and running). The combined 5-min mean variation of the
[`(T)]\nolimitssk \mathop{{\bar{T}}}\nolimits_{{sk}} RMSE was 1.5°C, with separate cycling and running giving RMSE of 1.4°C and 1.6°C, respectively, and no significant difference
in residuals. Subjects’ actual thermal sensation (ATS) votes displayed significant strong rank correlation with budget scores
calculated using both measured and predicted
[`(T)]\nolimitssk \mathop{{\bar{T}}}\nolimits_{{sk}} (r
s
= 0.507 and 0.517, respectively, P < 0.01). These results show improved predictive strength of ATS of subjects as compared to the original and updated COMFA
models. This psychological improvement, plus
[`(T)]\nolimitssk \mathop{{\bar{T}}}\nolimits_{{sk}} and T
c validations, enables better application to a variety of outdoor spaces. This model can be used in future research studying
linkages between thermal discomfort, subsequent decreases in physical activity, and negative health trends. 相似文献
4.
Cui-Ping Cao Oliver Gailing Iskandar Z. Siregar Ulfah J. Siregar Reiner Finkeldey 《Tree Genetics & Genomes》2009,5(3):407-420
Shorea is the largest and most important genus of the Dipterocarpaceae. The genetic diversity and structure of nine Shorea species from two different locations, namely Nanjak Makmur in Sumatra and Sumalindo in Borneo, were evaluated using amplified
fragment length polymorphism (AFLP) markers. A total of 274 trees were investigated at 85 polymorphic AFLP loci. Levels of
genetic diversity of these species ranged from = 0.100 for S. acuminata to = 0.165 for S. blumutensis. The population of rare species S. blumutensis possessed the highest genetic diversity suggesting that geographically restricted species can have levels of genetic variation
comparable to closely related widespread common congeners. Analyses of molecular variance revealed that the genetic variation
was mainly found among species in both locations (57.7% in Sumatra; 56.3% in Borneo). The unweighted pairgroup method using
arithmetic averages dendrogram of all samples revealed an almost complete separation of species. Thus, AFLP markers proved
appropriate for phylogenetic studies of Shorea species. Specific markers have been detected showing high-frequency differences among species and between regions within
species. Sequence information of these markers can be used to develop specific polymerase chain reaction markers for wood
identification. The possibility of interspecific hybridization was discussed. 相似文献
5.
Marilena Martins Pamboukian Soraia Athie Calil Jorge Mariza Gerdulo Santos Adriana Yurie Yokomizo Carlos Augusto Pereira Aldo Tonso 《Cytotechnology》2008,57(1):37-44
Specific respiration rate (
) is a key parameter to understand cell metabolism and physiological state, providing useful information for process supervision
and control. In this work, we cultivated different insect cells in a very controlled environment, being able to measure . Spodoptera frugiperda (Sf9) cells have been used through virus infection as host for foreign protein expression and bioinsecticide production.
Transfected Drosophila melanogaster (S2) cells can be used to produce different proteins. The objective of this work is to investigate respiratory activity and
oxygen transfer during the growth of different insect cells lines as Spodoptera frugiperda (Sf9), Drosophila melanogaster (S2) wild and transfected for the expression of GPV and EGFP. All experiments were performed in a well-controlled 1-L bioreactor,
with SF900II serum free medium. Spodoptera frugiperda (Sf9) cells reached 10.7 × 106 cells/mL and maximum specific respiration rate () of 7.3 × 10−17 molO2/cell s. Drosophila melanogaster (S2) cells achieved 51.2 × 106 cells/mL and of 3.1 × 10–18 molO2/cell s. S2AcGPV (expressing with rabies virus glycoprotein) reached 24.9 × 106 cells/mL and of 1.7 × 10–17 molO2/cell s, while S2MtEGFP (expressing green fluorescent protein) achieved 15.5 × 106 cells/mL and = 1.9 × 10−17 molO2/cell s. Relating to the Sf9, S2 cells reached higher maximum cell concentrations and lower specific respiration rate, which
can be explained by its smaller size. These results presented useful information for scale-up and process control of insect
cells. 相似文献
6.
The data processing method of the turbidimetric bioassay of nisin was modified to facilitate its industrial application. The
influence of the initial indicator concentration was minimized by a redefined specific dose of the bacteriocin as the quotient
between the titer of the added bacteriocin and the initial population density of the indicator in the suspension. It was found
that d
c = 0.125 μg ml−1 was the critical dose of nisin that can cause a complete inhibition of the indicator, Pediococcus acidilactici UL5, with an initial OD of 0.135. To eliminate the interference of the cell debris, an equation, , exploiting d
c, was formulated to obtain the intrinsic survival proportion. The use of the specific dose of the bacteriocin and the intrinsic
survival proportion as parameters of the dose/response curve greatly enhanced its repeatability and feasibility. A dual-dosage
approach was developed to further simplify the conventional standard dose/response curve method. 相似文献
7.
C Calvo F Martinez-Checa A Mota V Bejar E Quesada 《Journal of industrial microbiology & biotechnology》1998,20(3-4):205-209
The effects of monovalent and divalent cations on the rheological behavior of Halomonas eurihalina exopolysaccharide (EPS) were studied. Sodium, potassium, magnesium and calcium were added and the relative abilities to increase
viscosity were as follows: KCl > NaCl > MgCl2 > CaCl2. The highest viscosity value was measured in acidic 10−4 M KCl, in which a gel formed. A loss of sulfate content seemed to correlate with the increase of viscosity. H. eurihalina produced EPS in all growth media. Addition of hydrophobic substrates to culture media produced changes in chemical
composition and emulsifying activity of the EPS. Xylene was the most effectively emulsified substance and the EPS produced
on tetradecane and on corn oil the most active emulsifier.
Received 25 July 1997/ Accepted in revised form 30 January 1998 相似文献
8.
The reactions of trees to wind, rockfall, and snow and debris flow depend largely on how strong and deformable their anchorage
in the soil is. Here, the resistive turning moment M of the root–soil system as a function of the rotation ϕ at the stem base plays the major role. M(ϕ) describes the behavior of the root–soil system when subject to rotational moment, with the maximum M(ϕ) indicating the anchorage strength M
a of the tree. We assessed M(ϕ) of 66 Norway spruce (Picea abies L. Karst) by pulling them over with a winch. These 45- to 170-year-old trees grew at sites of low and high elevation, with
a diameter at breast height DBH = 14–69 cm and a height H = 9–42 m. M(ϕ) displayed a strong nonlinear behavior. M
a was reached at a lower ϕ for large trees than for small trees. Thus overhanging tree weight contributed less to M
a for the large trees. Overturning also occurred at a lower ϕ for the large trees. These observations show that the rotational ductility of the root–soil system is higher for small trees.
M
a could be described by four monovariate linear regression equations of tree weight, stem weight, stem volume and DBH
2
·H (0.80 < R
2 < 0.95), and ϕ at M
a, ϕ
a, by a power law of DBH2·H (R
2 = 0.85). We found significantly higher M
a for the low-elevation spruces than for the high-elevation spruces, which were more shallowly anchored, but no significant
difference in ϕ
a. The 66 curves of M(ϕ), normalized (n) by M
a in M-direction and by ϕ
a in ϕ-direction, yielded one characteristic average curve: . Using and the predictions of M
a and ϕ
a, it is shown that M(ϕ) and the curves associated with M(ϕ) can be predicted with a relative standard error ≤25%. The parameterization of M(ϕ) by tree size and weight is novel and provides useful information for predicting with finite-element computer models how
trees will react to natural hazards. 相似文献
9.
Soil Respiration in European Grasslands in Relation to Climate and Assimilate Supply 总被引:9,自引:0,他引:9
Michael Bahn Mirco Rodeghiero Margaret Anderson-Dunn Sabina Dore Cristina Gimeno Matthias Drösler Michael Williams Christof Ammann Frank Berninger Chris Flechard Stephanie Jones Manuela Balzarolo Suresh Kumar Christian Newesely Tibor Priwitzer Antonio Raschi Rolf Siegwolf Sanna Susiluoto John Tenhunen Georg Wohlfahrt Alexander Cernusca 《Ecosystems》2008,11(8):1352-1367
Soil respiration constitutes the second largest flux of carbon (C) between terrestrial ecosystems and the atmosphere. This
study provides a synthesis of soil respiration (R
s) in 20 European grasslands across a climatic transect, including ten meadows, eight pastures and two unmanaged grasslands.
Maximum rates of R
s (
), R
s at a reference soil temperature (10°C; ) and annual R
s (estimated for 13 sites) ranged from 1.9 to 15.9 μmol CO2 m−2 s−1, 0.3 to 5.5 μmol CO2 m−2 s−1 and 58 to 1988 g C m−2 y−1, respectively. Values obtained for Central European mountain meadows are amongst the highest so far reported for any type
of ecosystem. Across all sites was closely related to . Assimilate supply affected R
s at timescales from daily (but not necessarily diurnal) to annual. Reductions of assimilate supply by removal of aboveground
biomass through grazing and cutting resulted in a rapid and a significant decrease of R
s. Temperature-independent seasonal fluctuations of R
s of an intensively managed pasture were closely related to changes in leaf area index (LAI). Across sites increased with mean annual soil temperature (MAT), LAI and gross primary productivity (GPP), indicating that assimilate supply
overrides potential acclimation to prevailing temperatures. Also annual R
s was closely related to LAI and GPP. Because the latter two parameters were coupled to MAT, temperature was a suitable surrogate
for deriving estimates of annual R
s across the grasslands studied. These findings contribute to our understanding of regional patterns of soil C fluxes and highlight
the importance of assimilate supply for soil CO2 emissions at various timescales. 相似文献
10.
Effects of ambient temperature and altitude on ventilation and gas exchange in deer mice (Peromyscus maniculatus) 总被引:2,自引:1,他引:1
Mark A. Chappell 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1985,155(6):751-758
Summary The effects of different ambient temperatures (T
a) on gas exchange and ventilation in deer mice (Peromyscus maniculatus) were determined after acclimation to low and high altitude (340 and 3,800 m).At both low and high altitude, oxygen consumption (
) decreased with increasingT
a atT
a from –10 to 30 °C. The
was 15–20% smaller at high altitude than at low altitude atT
a below 30 °C.Increased
atT
a below thermoneutrality was supported by increased minute volume (
) at both low and high altitude. At mostT
a, the change in
was primarily a function of changing respiration frequency (f); relatively little change occurred in tidal volume (V
T) or oxygen extraction efficiency (O2EE). AtT
a=0 °C and below at high altitude,
was constant due to decliningV
T and O2EE increased in order to maintain high
.At high altitude,
(BTP) was 30–40% higher at a givenT
a than at low altitude, except atT
a below 10 °C. The increased
at high altitude was due primarily to a proportional increase inf, which attained mean values of 450–500 breaths/min atT
a below 0 °C. The
(STP) was equivalent at high and low altitude atT
a of 10 °C and above. At lowerT
a,
(STPD) was larger at low altitude.At both altitudes, respiratory heat loss was a small fraction (<10%) of metabolic heat production, except at highT
a (20–30 °C).Abbreviations
EHL
evaporative heat loss
-
f
respiration frequency
-
HL
a
heat loss from warming tidal air
-
HL
e
evaporative heat loss in tidal air
-
HL
total respiratory heat loss
-
MHP
metabolic heat production
-
O
2
EE
oxygen extraction efficiency
-
RQ
respiratory quotient
-
T
a
ambient temperature
-
T
b
body temperatureT
lc lower critical temperature
-
carbon dioxide production
-
evaporative water loss
-
oxygen consumption
-
minute volume
-
V
T
tidal volume 相似文献
11.
Jean-Philippe Bellenger Françoise Arnaud-Neu Zouhair Asfari Satish C. B. Myneni Edward I. Stiefel Anne M. L. Kraepiel 《Journal of biological inorganic chemistry》2007,12(3):367-376
Azotochelin is a biscatecholate siderophore produced by the nitrogen-fixing soil bacterium Azotobacter vinelandii. The complexation properties of azotochelin with a series of oxoanions [Mo(VI), W(VI) and V(V)] and divalent cations [Cu(II),
Zn(II), Co(II) and Mn(II)] were investigated by potentiometry, UV–vis and X-ray spectroscopy. Azotochelin forms a strong 1:1
complex with molybdate (log K = 7.6 ± 0.4) and with tungstate and vanadate; the stability of the complexes increases in the order Mo < V < W (log K
appMo = 7.3 ± 0.4; log K
appV = 8.8 ± 0.4 and log K
appW = 9.0 ± 0.4 at pH 6.6). The Mo atom in the 1:1 Mo–azotochelin complex is bound to two oxo groups in a cis position and to the two catecholate groups of azotochelin, resulting in a slightly distorted octahedral configuration. Below
pH 5, azotochelin appears to form polynuclear complexes with Mo in addition to the 1:1 complex. Azotochelin also forms strong
complexes with divalent metals. Of the metals studied, Cu(II) binds most strongly to azotochelin , followed by Zn(II) , Mn(II) and Co(II) . Since very few organic ligands are known to bind strongly to oxoanions (and particularly molybdate) at circumneutral pH,
the unusual properties of azotochelin may be used for the separation and concentration of oxoanions in the laboratory and
in the field. In addition, azotochelin may prove useful for the investigation of the biogeochemistry of Mo, W and V in aquatic
and terrestrial systems.
Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users. 相似文献
12.
Yinghui Dan 《In vitro cellular & developmental biology. Plant》2008,44(3):149-161
Browning and necrosis of transformed cells/tissues, and difficulty to regenerate transgenic plants from the transformed cells/tissues
(recalcitrance) are common in Agrobacterium-mediated transformation process in many plant species. In addition, most crop transformation methods that use NPTII selection
produce a significant number of nontransgenic shoots, called “shoot escapes” even under stringent selection conditions. These
common problems of plant transformation, (browning and necrosis of transformed cells/tissues, recalcitrance, and the occurrence
of shoot escapes) severely reduces transformation efficiency. Recent research indicates that reactive oxygen species (ROS)
such as superoxide radical , the hydrogen peroxide (H2O2), the hydroxyl radical (OH′), and the peroxyl radical () may be playing an important role in tissue browning and necrosis during transformation. This review examines the role of
ROS in in vitro recalcitrance and genetic transformation and the opportunities to improve transformation efficiency using antioxidants. 相似文献
13.
Due of its simplicity the shaking flask is used in serial studies, e.g. in the screening for secondary metabolites or in the optimization of fermentation processes. Experimental investigations in these small bioreactors are often the first step in developing a large-scale fermentation process.Movement of the flask should produce sufficient mixing, supply of oxygen, and removal of carbon dioxide. In the case of fluids with low or moderate viscosity, gas transport is the most important aspect. This publication summarizes data necessary to calculate the gas transport. These data are derived from the consideration of the gas diffusions through the cotton plug as well as from the substance transport between the gas and liquid phases. As a result suitable fermentation conditions can be selected. Finally, the performance limits of the shaking flask are illustrated using the example of the oxygen supply in a Streptomyces tendae fermentation.List of Symbols
A
s
Cross section of plug
-
A
Surface area of liquid in flask
-
a
A/V
F specific phase interface area
-
c
Concentration
-
c
*
Saturation concentration
-
c
Plug diffusion term
-
D
Widest diameter of flask
-
Diffusion coefficients in multicomponent gas mix tures
-
Diffusion coefficients in binary gas mixtures
-
Diffusion coefficient of oxygen in the liquid
-
d
Diameter of neck of flask
-
e
Eccentricity
-
G
Volume-based mass flow
-
G
m
Maximum volume-based mass flow
-
g
Acceleration due to gravity
-
h
Height coordinate
-
¯H
Mean height of plug
-
Hy
p
i/c
*, Henry constant
-
K
Consistency index
-
k
D
xy/D
xz, Ratio of diffusion coefficients in binary gas mixtures
-
k
M
Monod constant
-
k
L
a
Mass transport coefficient: gas/liquid
-
M
Molecular weight
-
m
Flow exponent
-
n
Speed of shaking
-
p
Pressure
-
p
i
Partial pressure of gas component i
-
q
Area-based flow of volume
-
R
, respiration ratio
-
Sc
, Schmidt number
-
T
Absolute temperature
-
V
Flask volume
-
V
F
Volume of liquid in flask
-
w
Velocity of the Stefan flow
-
x, y, z
Ratios of the partial pressures of the gases O2, CO2, N2
-
Rate of shear
-
Dynamic viscosity of the liquid
-
Kinematic viscosity of the liquid
-
Density of the liquid
-
x,
Density of O2 gas
-
Surface tension
Indices 0
State in gas volume of shaking flask
- 1
State in outside air
- G
Gas volume
- x, y, z
O2, CO2, N2 相似文献
14.
Summary A set of three-dimensional triple-resonance experiments is described which provide
,
,
and
coupling constants. The pulse sequences generate E.COSY-like multiplet patterns and comprise a magnetization transfer from
the amide proton to the α-proton or vice versa via the directly bound heteronuclei. For residues with the 1Hα spin resonating close to the H2O signal, a modified HNCA experiment can be employed to measure the vicinal 1HN,1Hα couplings. Ambiguities associated with the conversion of
values into ϕ-angle constraints for protein structure determination can be resolved with the knowledge of the heteronuclear
3J-couplings. In favourable cases, stereospecific assignments of glycine α-protons can be obtained by employing the experiments
described here in combination with NOE data. The methods are applied to flavodoxin from Desulfovibrio vulgaris. 相似文献
15.
In this paper, we consider a circular central aperture surrounded with annular depth-tuned grooves and investigate the beaming
effect of the structure under illumination of a circularly polarized (CP) plane wave. As a CP plane wave is equivalent to
the superposition of two linearly polarized plane waves (TM and TE) with a phase difference of π/2, the superposition of the
electric field intensity, ( | Ex |2 + | Ey |2 ) \left( {{{\left| {E_x} \right|}^2} + {{\left| {E_y} \right|}^2}} \right) , is observed in the transmission field. In addition, two plasmonic modes are found at the resonant wavelengths λ
1 and λ
2 with each consisting of multiple wavelengths. At the wavelength λ
1 = 420 nm, the significant near-field collimation is formed along the direction z, having a long propagation distance up to 1.75 μm (≈4λ) away from the exit plane of the new plasmonic lens. 相似文献
16.
17.
The aim of our work was to study the anti-aggregatory and antioxidative effects of natural dietary products, d-glucaro 1,4-lactone (1,4-GL) in combination with phenolic compound resveratrol (trans-3,4′,5-trihydroxystilbene). Our results in vitro showed that 1,4-GL alone slightly inhibits platelet aggregation induced
by thrombin. The combination of resveratrol (0.1 μM) with 0.5 mM of 1,4-GL caused a significant decrease of thrombin-induced
platelet aggregation; however separately, neither of studied compound at used concentrations was not effective. When platelets
were treated with 1,4-GL (at the concentration of 0.1 mM and higher) and resveratrol (0.1 μM), similar synergistic action
of both tested compound on markers of oxidative stress formation was observed. We measured the levels of different specific
markers of oxidative stress, e.g., superoxide anion radicals , thiobarbituric acid-reactive substances and carbonyl group formation. Both tested compounds inhibited also the generation
of and malondialdehyde that represents enzymatical peroxidation of arachidonic acid leading to thromboxane A2 (TXA2) formation in platelets after thrombin stimulation. The obtained in vitro results demonstrate that anti-platelet and antioxidative
properties of resveratrol may be significantly augmented by another dietary agent such as 1,4-GL, but mechanism synergistic
action of these compounds is not yet known. 相似文献
18.
Nolte R Mühlbradt KH Meulders JP Stephan G Haney M Schmid E 《Radiation and environmental biophysics》2005,44(3):201-209
The production of dicentric chromosomes in human lymphocytes by high-energy neutron radiation was studied using a quasi-monoenergetic
60 MeV neutron beam. The average yield coefficient
of the linear dose–response relationship for dicentric chromosomes was measured to be (0.146±0.016) Gy−1. This confirms our earlier observations that above 400 keV, the yield of dicentric chromosomes decreases with increasing
neutron energy. Using the linear-quadratic dose–response relationship for dicentric chromosomes established in blood of the
same donor for 60Co γ-rays as a reference radiation, an average maximum low-dose RBE (RBEM) of 14±4 for 60 MeV quasi-monoenergetic neutrons with a dose-weighted average energy
of 41.0 MeV is obtained. A correction procedure was applied, to account for the low-energy continuum of the quasi-monoenergetic
spectral neutron distribution, and the yield coefficient α for 60 MeV neutrons was determined from the measured average yield coefficient
. For α, a value of (0.115±0.026) Gy−1 was obtained corresponding to an RBEM of 11±4. The present experiments extend earlier investigations with monoenergetic neutrons to higher energies. 相似文献
19.
Roberto Gomes da Silva Magda Maria Guilhermino Débora Andréia E. Façanha de Morais 《International journal of biometeorology》2010,54(1):5-11
The goal of the present paper was to assess a method for estimating the thermal radiation absorbed by dairy cows (0.875 Holstein–0.125
Guzerath) on pasture. A field test was conducted with 472 crossbred dairy cows in three locations of a tropical region. The
following environmental data were collected: air temperature, partial vapour pressure, wind speed, black globe temperature,
ground surface temperature and solar radiation. Average total radiation absorbed by animals was calculated as Rabs = 640.0 ±3.1 W.m - 2 {R_{abs}} = 640.0 \pm 3.1\, W.{m^{ - 2}} . Absorbed short-wave radiation (solar direct, diffuse and reflected) averaged 297.9 ± 2.7 W m−2; long wave (from the sky and from terrestrial surfaces) averaged 342.1 ± 1.5 W m−2. It was suggested that a new environmental measurement, the effective radiant heat load (ERHL), could be used to assess the
effective mean radiant temperature
( T\textmr* ) \left( {T_{\text{mr}}^* } \right) . Average
T\textmr* T_{\text{mr}}^* was 101.4 ± 1.2°C, in contrast to the usual mean radiant temperature, Tmr = 65.1 ±0.5° C {T_{mr}} = 65.1 \pm 0.5^\circ C . Estimates of
T\textmr* T_{\text{mr}}^* were considered as more reliable than those of T
mr in evaluating the thermal environment in the open field, because T
mr is almost totally associated only with long wave radiation. 相似文献
20.
Stephen H. Boutcher Phyllis Stein 《European journal of applied physiology and occupational physiology》1995,70(1):75-80
The effect of exercise training on heart rate variability (HRV) and improvements in peak oxygen consumption (
peak) was examined in sedentary middle-aged men. The HRV and absolute and relative
peak of training (n = 19) and control (n = 15) subjects were assessed before and after a 24-session moderate intensity exercise training programme. Results indicated that with exercise training there was a significantly increased absolute and relative
peak (P < 0.005) for the training group (12% and 11% respectively) with no increase for the control group. The training group also displayed a significant reduction in resting heart rate; however, HRV remained unchanged. The trained subjects were further categorized into high (n = 5) and low (n = 5) HRV groups and changes in
peak were compared. Improvements in both absolute and relative
peak were significantly greater (P > 0.005) in the high HRV group (17% and 20% respectively) compared to the low HRV group (6% and 1% respectively). The groups did not differ in mean age, pretraining oxygen consumption, or resting heart rate. These results would seem to suggest that a short aerobic training programme does not alter HRV in middle-aged men. Individual differences in HRV, however, may be associated with
peak response to aerobic training. 相似文献