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1.
This paper presents a model for the single-stage completely-mixed anaerobic digestion of complex substrates containing no volatile acids. In the model, volatile acids produced by the acidogenic bacteria are no longer considered together. Acetate is assumed to be representative of the substrate and propionate and butyrate act only as inhibitors for the methanogenic bacteria.Nomenclature ···0
represents factors associated with the influent
- ···1
represents factors associated with the acidogenic bacteria
- ···2
represents factors associated with the methanogenic bacteria
- Q
hydraulic flow (1/d)
- V
reactor liquid volume (1)
- T
temperature of the mixed liquor (° C)
- S
microorganisms concentration (mg/1)
- L
volatile solids concentration (mg VS/1)
- Lb
biodegradable volatile solids concentration (mg VS/1)
- VA2
acetate concentration (mg/1)
- VA3
volatile acids with 3 to 5 carbon atoms concentration (mg/1)
-
methane rate production (1 CH4/1digester.d)
- Km
saturation coefficient (mg/l)
- Ki
inhibition coefficient (mg/l)
-
specific growth rate (1/d)
-
maximum specific growth rate (1/d)
- b
biological decay coefficient (1/d)
-
Arrhénius coefficient (–)
-
yield of acidogenic bacteria per mg of biodegradable matter consumed (mg S1/mg Lb) | (mg S2/mg VA2)
-
yield of methanogenic bacteria per mg of VA2 consumed
-
yield of methane production per mg of S2 formed (1 CH4/mg S2)
-
proportion of VA2 produced per mg of S1 biosynthetised
-
proportion of VA3 produced per mg of S1 biosynthetised
- Ysp
volume of CH4 produced per g of volatile solids eliminated 相似文献
2.
High groundwater nitrate concentrations inhibit eutrophication of sulphate-rich freshwater wetlands 总被引:2,自引:0,他引:2
E.C.H.E.T. Lucassen A.J.P. Smolders A.L. van der Salm J.G.M. Roelofs 《Biogeochemistry》2004,67(2):249-267
During the last 60 years, pollution of the groundwater with
has greatly increased in many parts of Europe, as a consequence of excessive use of manure and synthetic fertilisers. Monitoring of groundwater-fed wetlands indicated that sediments with high
concentrations had the lowest Fe and
concentrations in the pore water. A comparison of two restored open water fens, differing in
supply via the groundwater, indicated that the redox potential and the sulphate (
) reduction rate were lower when the groundwater contained not only
but also high
concentrations. The lower
reduction rates in the
-rich open water fen were associated with lower
concentrations and the presence of plant species characteristic of clear water. In contrast, the higher
reduction rates in the
-poor open water fen were associated with very high
concentrations and massive development of plant species characteristic of eutrophic environments. Investigations at
-rich seepage sites in black alder carrs, showed that high
concentrations in the pore water caused chlorosis in the alder carr vegetation, due to lower availability of Fe in the pore water and less Fe uptake by the plants. Experimental desiccation of sediments proved that the
-rich seepage sites contained no oxidisable FeS
x
, contrary to
-poor locations, which became acidified and mobilised extremely high amounts of
due to FeS
x
oxidation. A laboratory experiment showed that
addition to sediments led to reduced releases of Fe,
and S2–, very likely due to the oxidation of reduced Fe and S compounds. Overall, the results confirmed that
is an energetically more favourable electron acceptor in anaerobic sediments than Fe and
, and that high
loads function as a redox buffer, preventing reduction of Fe and
. Limited
reduction prevents S2– -mediated mobilisation of
from Fe-
complexes. At a higher redox potential, reduced Fe, including FeS
x
, was oxidised, increasing the content of Fe(III) capable of binding
. This prevented increased
availability and the concomitant massive development of plant species characteristic of eutrophic environments. 相似文献
3.
Gregory K. Snyder Wesley W. Weathers 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1977,117(3):291-301
Summary Resting rates of O2 consumption
against
, exercise endurance times and
during recovery from vigorous exercise were measured inSceloporus occidentalis captured near sea level and inS. graciosus captured above 2850 m. Oxygen consumption against
was also measured inS. occidentalis captured above 2850 m. When
was recorded continuously, as ambient
was slowly reduced from 155 Torr, it became directly dependent upon ambient
between 110 and 120 Torr. The critical
for the high altitude lizards was lower than that for the lowland lizards, which enabled the former to maintain relatively higher
's when ambient
was reduced below 120 Torr. The high altitude lizards also had significantly greater endurance when stimulated to exercise at 1600 m (
130 Torr). Both the higher
under hypoxia and the greater endurance roughly parallel a significantly greater maximum
in the high altitude lizards. At a simulated altitude of 3600 m (
100 Torr), maximum
and rate of recovery of the O2 debt calculated from post active
were significantly reduced in the lowland but not the high altitude lizards. The effects of simulated altitude conditions on the lowland but not the mountaine animals indicate adaptations to altitude in these sceloporine lizards. We did not find any consistent relationship between organ/body weight ratios or hematocrit and our measures of
endurance or the altitude at which the lizards were captured. 相似文献
4.
Intermittent drainage of rice fields isdiscussed as an option to mitigate emission ofCH4, an important greenhouse gas. HoweverN2O, a potentially more effective greenhouse gas,may be emitted during the aeration phase. Therefore,the metabolism of NO, N2O, NH
,NO
and NO
and the kinetics ofCH4 oxidation were measured after aeration ofmethanogenic rice field soil. Before aeration, thesoil contained NH
in relatively highconcentrations (about 4 mM), while NO
andNO
were almost undetectable. Immediatelyafter aeration both NO and N2O were produced withrates of about 15 pmol h-1 gdw-1 and 5 pmolh-1 gdw-1, respectively. Simultaneously,NH
decreased while NO
accumulated. Later on, NO
was depletedwhile NO
concentrations increased.Characteristic phases of nitrogen turnover wereassociated with the activities of ammonium oxidizers,nitrite oxidizers and denitrifiers. Oxidation ofNH
and production of NO and N2O wereinhibited by 10 Pa acetylene demonstrating thatnitrification was obligatory for the initiation ofnitrogen turnover and production of NO and N2O.Ammonium oxidation was not limited by the availableNH
and thus, concomittant production of NOand N2O was not stimulated by addition ofNH
. However, addition of NO
stimulated production of NO and N2O in bothanoxic and aerated rice soil slurries. In this case,10 Pa acetylene did not inhibit the production of NOand N2O demonstrating that it was due todenitrification which was obviously limited by theavailability of NO
. In the aerated soilslurries CH4 was only oxidized if present atelevated concentrations >50 ppmv CH4). Atatmospheric CH4 concentrations (1.7 ppmv)CH4 was not consumed, but was even slightly produced.CH4 oxidation activity increased afterpreincubation at 20% CH4, and then CH4was also oxidized at atmospheric concentrations. CH4oxidation kinetics exhibited sigmoid characteristicsat low CH4 concentrations presumably because ofinhibition of CH4 oxidation by NH
. 相似文献
5.
Didier G. Arqués Jean-Paul Fallot Christian J. Michel 《Bulletin of mathematical biology》1998,60(1):163-194
The self-complementary subset
∪{AAA,TTT} with
= {AAC, AAT, ACC, ATC, ATT, CAG, CTC, CTG, GAA, GAC, GAG, GAT, GCC, GGC, GGT, GTA, GTC, GTT, TAC, TTC} of 22 trinucleotides
has a preferential occurrence in the frame 0 (reading frame established by the ATG start trinucleotide) of protein (coding)
genes of both prokaryotes and eukaryotes. The subsets
∪{CCC} and
∪{GGG} of 21 trinucleotides have a preferential occurrence in the shifted frames 1 and 2 respectively (frame 0 shifted by
one and two nucleotides respectively in the 5′-3′ direction).
and
are complementary to each other. The subset
contains the subset
which has the rarity property (6 × 10−8) to be a complementary maximal circular code with two permutated maximal circular codes
and
in the frames 1 and 2 respectively.
is called a C3 code.
A quantitative study of these three subsets
in the three frames 0, 1, 2 of protein genes, and the 5′ and 3′ regions of eukaryotes, shows that their occurrence frequencies
are constant functions of the trinucleotide positions in the sequences. The frequencies of
in the frame 0 of protein genes are 49, 28.5 and 22.5% respectively. In contrast, the frequencies of
in the 5′ and 3′ regions of eukaryotes, are independent of the frame. Indeed, the frequency of
in the three frames of 5′ (respectively 3′) regions is equal to 35.5% (respectively 38%) and is greater than the frequencies
and
, both equal to 32.25% (respectively 31%) in the three frames.
Several frequency asymmetries unexpectedly observed (e.g. the frequency difference between
and
in the frame 0), are related to a new property of the subset
involving substitutions. An evolutionary analytical model at three parameters (p, q, t) based on an independent mixing of the 22 codons (trinucleotides in frame 0) of
with equiprobability (1/22) followed by t ≈ 4 substitutions per codon according to the proportions p ≈ 0.1; q ≈ 0.1 and r = 1 − p − q ≈ 0.8 in the three codon sites respectively, retrieves the frequencies of
observed in the three frames of protein genes and explains these asymmetries. Furthermore, the same model (0.1, 0.1, t) after t ≈ 22 substitutions per codon, retrieves the statistical properties observed in the three frames of the 5′ and 3′ regions.
The complex behaviour of these analytical curves is totally unexpected and a priori difficult to imagine. 相似文献
6.
Pierre Dejours Jean-Paul Truchot 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1988,158(3):387-391
Summary In the intertidal shore crab,Carcinus maenas, pH and
values of the prebranchial venous hemolymph,
and
, the PO2 values of the arterialized cardiac hemolymph,
, were measured, and the ventilatory activity was assessed by measuring the hydrostatic pressures at the exits of the epibranchial cavities, under four environmental conditions: normoxic water, normoxic air, hypoxic gas, hyperoxic gas.In the crab breathing normoxic air,
was lower and
higher than in animals breathing normoxic water. With the switch to hypoxic gas, ventilation increased and
and
decreased. With the switch to hyperoxic gas, ventilation decreased,
and
increased and
decreased.Thus these crabs breathing air were not as well oxygenated as when breathing air-equilibrated water, and because of their low
, they were relatively hypervetilating and hypocapnic compared to air-breathing vertebrates. Hyperoxic breathing, increasing
and reducing ventilatory drive, led to increased
. Conversely,
was reduced by hypoxic breathing. These observations suggest that the gas exchanger of intertidal crabs is not as successfully designed for air breathing as that of land-colonizing insects and air-breathing vertebrates. 相似文献
7.
M. Christopher Barnhart 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1986,156(3):347-354
Summary Control of extracellular acid-base status was examined during activity and dormancy inOtala lactea (Pulmonata, Helicidae). Active snails showed little variation in hemolymph pH and
at constant temperature. With increase of temperature, hemolymph
increased from about 6 Torr at 5°C to 13 Torr at 24°C and pH decreased by about 0.017 pH units/°C, a pattern consistent with alphastat regulation of pH via ventilatory control of
.During dormancy, mean hemolymph
increased to about 50 Torr. Venous pH declined by about 0.4 units due to hypercapnia and fluctuated more widely than in active snails due to variability of
. Hemolymph pH declined further in prolonged dormancy due to progressive metabolic acidosis; after one year of dormancy the mean hemolymph pH was about 0.8 units lower than that of active snails at similar temperature.Active snails exposed experimentally to high
showed a large increase in hemolymph [HCO
3
–
]. However, [HCO
3
–
] declined by up to 50% during dormancy, despite the naturally occurring hypercapnia. Hemolymph osmolality and the concentrations of solutes other than [HCO
3
–
] increased with increasing duration of dormancy. Concentrations of magnesium and calcium increased about 2.5 times more rapidly than those of sodium and chloride, indicating that acidosis is partially offset by the dissolution of carbonates from the shell or tissues. 相似文献
8.
Summary The genetic behaviour of a human serum -lipoprotein factor, called Ag(a1), was studied by agar micro-diffusion technique, utilizing an antibody detected in the serum from a transfused thalassemia patient. It behaves as an inherited, dominant, autosomal character, with complete penetrance at birth. It is controlled by a gene
and is closely linked to the Ag
x
and Ag
y
genes.The existence of a gene Ag
b
, allelic to
, is postulated but the Ag(b) antigen has not so far been detected by specific antisera.The frequency of the
gene in a Milan population was found to be 0,43, and in a Berne population was 0,46. The frequencies of the four possible gene combinations in the sample group from Milan were: Ag
yb
=0,53;
=0,22;
=0,21; Ag
xb
=0,04.The observed frequencies of the factor Ag(a1) were 0,676 and 0,713, respectively among the Milan and Berne populations. 相似文献
9.
Boniface S. Moses 《Environmental Biology of Fishes》2001,61(1):99-109
This paper investigates the relationship between the hydroclimatic parameters (rainfall and flood index) and the catch, stock abundance and recruitment of the catfish, Chrysichthys nigrodigitatus (Bagridae) and the bonga, Ethmalosa fimbriata (Clupeidae) of southeastern Nigeria's inshore waters. For C. nigrodigitatus, most peaks in the mean biomass
and recruitment
curves occurred during the 'wet' years, i.e., years for which the percentage deviations of rainfall
and flood index
from their means remained above their averages. Catch and abundance respectively showed good positive linear correlation with the flood index. E. fimbriata behaved differently; some peaks in the
and
curves occurred in the 'wet' and some in the 'dry' years; and there was no correlation between the annual catch of bonga and either the rainfall or the flood index. The hypothesis, that linear relationships exist between the interannual variations in the hydroregime and the yearly fluctuations in the catch and population structure of some coastal and estuarine fishes, holds true for the catfish, C. nigrodigitatus, but not for bonga, E. fimbriata. 相似文献
10.
Phytotoxicity of aluminium-fluoride complexes and their uptake from solution culture by Avena sativa and Lycopersicon esculentum 总被引:1,自引:0,他引:1
Avena sativa (oats) and Lycopersiconesculentum (tomatoes) were grown in dilute nutrientsolutions supplemented with Al only, F only or acombination of both. In solutions containing Al andF, shoot growth was limited when predicted Alr(Al3+, AlOH2+ and Al(OH)
)activities were < 0.1 M, activities three orders ofmagnitude lower than the critical value determinedwith Al only. The data suggest that at the activitiesused in these experiments, Alr is most toxic,AlF2+ and AlF
are toxic to a lesserextent, and AlF3, AlF
and F-are least toxic. Fluoride concentrations in shootsgrown in solutions correlated best with positivelycharged AlF
species (i.e.AlF2+, AlF
) and the molar ratio ofF:Al in most plants shoots was about 3:2. However,when activities of positively chargedAlF
species were low (< 50 M)and theactivity of AlF3 species high (500 M) the molarratio of F:Al in plant shoots suggested AlF3 wastaken up. These findings are discussed in relation toplant uptake and toxicity. Measured concentrations of Alr and F- insolutions containing Al and F were compared withconcentrations predicted by a computer model(GEOCHEM-PC). The method for measuring F-concentrations, using a non-complexing buffer and Fion-selective electrode, gave good agreement withpredicted F- concentrations. The8-hydroxyquinoline method for measuring Alrconcentrations did not agree with predictedconcentrations, highlighting the limitations of thismethod when measuring Alr in the presence of F ina multi-ligand system with high concentrations of Fand Al. 相似文献
11.
G. Percheron F. Brechignac Ph. Soucaille J. -St. Condoret 《Bioprocess and biosystems engineering》1995,12(1-2):11-16
The ability of oxygen vector to extract produced carbon dioxide has been tested in an anaerobic fermentation. During the continuous culture of Clostridium acetobutylicum at pH 4.6 and at a dilution rate of 0.124 h–1, a feed composed of an emulsion of 18.5% by volume of Forane F66E was able to extract about 9% of the total CO2 produced under CO2 partial pressure equal to 0.42 atm. A theoretical evaluation of the extracted amount, based on the hypothesis of total saturation of the vector by carbon dioxide, has lead to very good agreement.List of Symbols [AA] g/l
acetic acid concentration
- [BA] g/l
butyric acid concentration
- D 1/h
Q
w
/V dilution rate
- [ETH] g/l
ethanol concentration
-
H
w
Henry constant of CO2 for water at 37°C (=23.91 mmol/(l atm))
-
H
F
Henry constant of CO2 for Forane at 37°C (=83.4 mmol/(l atm))
-
H
i
g/mol
molar mass of componenti
-
P
i
atm
partial pressure of gasi
-
W
w
l/h
aqueous flow
- Qf 1/h
Forane flow
-
mmol/(lh)
dissolved CO2 flow in aqueous effluent
-
mmol/(lh)
CO2 gas flow
-
mmol/(lh)
CO2 gas flow without Forane
-
mmol/(lh)
CO2 gas flow with Forane
-
mmol/(lh)
total CO2 production
-
r
X
g/(lh)
biomass production rate
-
r
G
mmol/(lh)
total gas flow
-
mmol/(lh)
hydrogen production
-
mmol/(lh)
nitrogen flow
-
r
S
mmol/(lh)
glucose input
-
V 1
fermentor volume 相似文献
12.
Ole Brix Gunnar Lykkeboe Kjell Johansen 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1979,129(2):97-103
Summary Oxygen binding properties of the hemocyanin-containing blood ofBuccinum undatum were examined in vitro and in vivo under normoxic (
150 mmHg) and hypoxic (
50 mmHg) conditions at 10°C. Blood pH and
showed a decrease in vivo under hypoxic conditions. Oxygen uptake at high water
, was about 18 ml O2/kg·h (wet weight) and the critical oxygen tension between 25 and 50 mm Hg. In vitro the O2 binding to hemocyanin showedn-values independent of pH, while both O2 affinity and oxygen carrying capacity were strongly pH dependent. Oxygen affinity increased below pH=8.1 and thus showed a pronounced reversed Bohr shift in the physiological pH range (7.5<pH<8.1). The oxygen carrying capacity similarly increased markedly with falling pH in the physiological pH range (reversed Root shift). Astrup titration curves showed a metabolic and respiratory acidosis under hypoxic conditions (
50 mm Hg). The role of hemocyanin in the transport of oxygen in relation to ambient O2 availability is discussed. 相似文献
13.
H. Kaspar von Meyenburg 《Archives of microbiology》1969,66(4):289-303
Summary A method for the estimation of the yield on energy (Y
ATP) and of the efficiency of oxidative phosphorylation, in vivo (P/O ratio) is described, which is based on the measurement of effective gas exchange values (
and
) and of the yield coefficient Y of continuously growing populations of baker's yeast which vary in the degree of fermentation and respiration. For Y
ATP a value of 12.0±0.5
and for P/O ratio one of 1.1±0.05
was found and seems to be independent of the type of glucose catabolism (under glucose limitation).The gas exchange of populations of Saccharomyces cerevisiae synchronized at different growth rates was determined. The specific oxygen uptake and carbon dioxide formation rate, Q
O
2, and Q
CO
2, are shown to depend on the state of the cells in the budding cycle. Increase in gas metabolism and therefore increased energy generation coincides with the initiation of budding. The longer the generation time g the more expressed are these oscillations of energy formation over the budding cycle. The relationship between the course of energy generation and energy storage and the sequence of budding and single cell phase over the division cycle is discussed. 相似文献
14.
Canadian populations of D. radicum differ in their response to temperature during postdiapause development. Populations that are primarily of the early-emerging type (
) (St-Jean, Quebec; London, Ontario) have high values for the parameters describing this response: % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOuamaaBa% aaleaacaWGTbaabeaakiabg2da9aaa!38F2!$$R_m = $$ 12.7–13.3;
28.0–31.8 °C ; T = 10.3–14.2 (
, the maximum developmental rate at the temperature,
[ °C ] where the developmental rate is highest, and T , the parameter which gives the shape of the truncated normal curve fitted to the data), a low degree-day requirement for emergence (160–232
), and may lack a developmental delay at temperatures above ca. 21 °C . Populations of the late-emerging type (Kildare, Prince Edward Island) have low parameter values (
,
°C ; T = 6.4), high degree-day requirements (530
), and a developmental delay at high temperatures. The parameters for the early-emergers in the population from Winnipeg, Manitoba (74% early) were intermediate (
,
°C , T = 10.7,
), but resembled the early rather than the late type. This population varied from 31 to 90% early type over a 10-year period and the rate of postdiapause development at 20 °C was directly related to the percentage early. In the year with the most rapid development (90% early), development was significantly slower than in the populations from other locations with predominantly early populations, and the year with the slowest development (31% early) showed significantly faster development than that from Kildare, Prince Edward Island (100% late). Therefore the parameters for early and late types of development will not be accurate for use in mixed populations, and the parameters in mixed populations will change among years. Populations of D. radicum in North America and Europe (67 locations by years) varied from 0–100% early. At Winnipeg, the percentage early was directly related to the annual temperature accumulation (
) during the growing season. The calculation of developmental parameters for the early-emergers of mixed populations provides a more accurate basis for estimating the times of first emergence and the first peak of emergence than parameters based on the whole population. Since postdiapause developmental rates vary both among and annually within locations, developmental models should be designed to include such variations. 相似文献
15.
Sheroziya O. P. Ermishkin V. V. Lukoshkova E. V. Mazygula E. P. Ryb'yakova V. B. Chepetova T. V. 《Neurophysiology》2003,35(6):434-444
In 19 tested persons in the resting lying position, we examined changes in the mean duration of R-R intervals
and in parasympathetic chronotropic cardiac reactions (respiratory arrhythmia,RA, and swallowing-related tachycardia, ST) induced by intensified tonic parasympathetic influences after peroral administration of antagonists of muscarinic (M) receptors in small doses. Administration of 0.02 g of an extract of Belladonna, which contains alkaloids of the atropine group, led to a significant
increase (P < 0.001). In this case, the RA at the natural frequency of breathing (P < 0.05) and ST (P < 0.001) simultaneously increased. Close correlation was observed both between initial values of the ST and
in various tested persons (r = 0.87) and between changes in these values, which were induced by the action of small amounts of M antagonists (r = 84). In various persons, the RA during deep slowed breathing (6 min-1, RA6) demonstrated ambiguous modifications. In the structure of RA6, we identified two components: an inspiratory tachycardic (TC) and an expiratory bradycardic (BC). With intensification of the parasympathetic influences, the TC began to prevail; its increase was strongly related to a rise in the
(r = 0.84). In contrast, correlation between changes in the BC and an increase in the
was completely absent (r = 0.001). Therefore, small amounts of M antagonists intensify both the tonic component of parasympathetic control (increasing the
) and its dynamic indices, the magnitudes of the ST and RA. Tachycardia during swallowing and the inspiratory TC under conditions of deep slowed breathing are closely related to changes in the parasympathetic influences. The magnitude of the RA is the index, which reflects the tonic component of chtonotropic control under conditions of both slowed and natural breathing less adequately than the ST. 相似文献
16.
Fumio Yamazaki Ryoko Sone Nobuharu Fujii Haruo Ikegami 《International journal of biometeorology》1993,37(4):212-217
Based on the hypothesis that the relation between sweating rate and body temperature should be different during exercise and rest after exercise, we compared the sweating response during exercise and recovery at a similar body temperature. Healthy male subjects performed submaximal exercise (Experiment 1) and maximal exercise (Experiment 2) in a room at 27° C and 35% relative humidity. During exercise and recovery of 20 min after exercise, esophageal temperature (Tes), mean skin temperature, mean body temperature (
), chest sweating rate (
), and the frequency of sweat expulsion (F
SW) were measured. In both experiments,
andF
SW were clearly higher during exercise than recovery at a similar body temperature (Tes,
).
was similar during exercise and recovery, or a little less during the former, at a similarF
SW. It is concluded that the sweating rate during exercise is greater than that during recovery at the same body temperature, due to greater central sudomotor activity during exercise. The difference between the two values is thought to be related to non-thermal factors and the rate of change in mean skin temperature. 相似文献
17.
Summary The postulate that 60-Hz electric field-induced bioeffect severity is proportional to induced transmembrane potential [
] magnitude was tested and supported using a plant root model cell system. Statistically significant correlations were obtained upon regression of the relative rates of exposedVicia faba andZea mays root segment growth on the average
(calculated) arising in those segments under specified 60 Hz field exposure conditions. The
associated with the apparent threshold for growth inhibition was similar inZea andVicia roots (2.5 vs 2.4 mV, respectively). At
greater than this threshold,Zea root growth declined by about 9% per mV, andVicia root growth by about 19% per mV induced potential.Abbreviations EF
electric field
- RGR
relative growth rate
- RSGR
relative segmental growth rate
-
induced membrane potential
-
segmental-average induced membrane potential
-
VC
d
region of root tip in which a complete, nascent vascular cylinder is first distinguishable in histological sections 相似文献
18.
Summary The complete sequence of the 5S rRNA from the bioluminescent bacterium,Beneckea harveyi has been determined to be p U G C U U G G C G
C C A U A G C G A
U U-G G A C C C A
C U G A (U) C U U C
A U U C C-G A A C
C A G A A G U G A
A C G A A U U A-G
G C C G A U G G U
G U G U G G G G C
U-C C C C A U G U
A G A G U A G G A
A U C G-C C A G G
U (U)OH.Two sites of sensitivity to ribonuclease T2 cleavage were identified; at A41 and either A54 or A55. Comparison with existing sequence information fromEscherichia coli andPhotobacterium phosphoreum clarifies the amount of diversity among the bioluminescent bacteria and provides further insight into their phylogenetic position. Sequence heterogeneities were encountered and the importance of these in interpreting 5S rRNA data is discussed. 相似文献
19.
To evaluate the order and the values of Markov properties of the time series of events, we have proposed a statistical measure dependency:D
m
= (H
0
–H
m
)/H
0
, whereH
0 andH
m are Shannon's entropy and them-th order conditional entropy, respectively. It is indicated that
is a better point estimator ofD
m, giving a total value of them-th order Markov process. Here
and
are the estimate ofD
m and the arithmetic mean of
when them-th order shuffling is made many times for a given observed series, respectively. The value
represents Markov value of the orderm. Under the assumption that the series has continuous variables and the normal distribution, simplified dependency is defined by, where |S
m
| is the determinant of serial correlation coefficients. It is shown that is practically useful for the estimation of the order and the values of Markov processes with small sample size. It is also indicated that analysis is basically equivalent to the least mean-square analysis of autoregressive models. 相似文献
20.
Mark A. Chappell Tamir M. Ellis 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1987,157(2):227-235
Summary Resting metabolic rates (RMR) of 34 species from 18 genera of boas and pythons (Serpentes: Boidae), with body masses ranging from 2 to 67,800 g, were determined as oxygen consumption (
) and carbon dioxide production (
) at three ambient temperatures (T
a).The temperature coefficient of metabolism (Q10) averaged 2.61 betweenT
a of 20–30°C and 2.65 between 30 and 34°C. The respiratory exchange ratio RE (=
/
) increased slightly with increasingT
a (0.795 at 20°C, 0.819 at 30°C, and 0.834 at 34°C). Interspecific differences in Q10 and RE were slight or insignificant.A multiple regression relating metabolism (
) to mass andT
a explained 97% of the variance in the pooled interspecific data. The mass exponent was 0.806, which is approximately the same as reported for squamates and for all reptilian taxa combined. The mean within-species slope (0.732) was significantly less than the slope for pooled data, but did not differ significantly from 0.75. In 40 of 42 cases (14 species at 3T
a), within-species slopes did not differ from each other. Values of the adjusted mean Y, from covariance analysis, were significantly and positively correlated with mass, indicating that the mass coefficient increases with increasing mass.Considerable variation in metabolic rate is apparent both within and between ecological and taxonomic categories.Original metabolic data are available from the National Auxiliary Publications Services, c/o Microfiche Publication, P.O. Box 3153 Grand Central Station, New York, New York 10017, USA 相似文献