\sqrt 2 Rule for Controlling the Tree Pattern in Forest Cut

A forest’s productivity can be optimized by the application of rules derived from monopolized circles. A monopolized circle is defined as a circle whose center is a tree and whose radius is half of the distance between the tree itself and its nearest neighbor. Three characteristics of monopolized circle are proved. (1) Monopolized circles do not overlay each other, the nearest relationship being tangent. (2) “Full uniform pattern” means that the grid of trees (a×b=N) covers the whole plot, so that the distance between each tree in a row is the same as the row spacing. The total monopolized circle area with a full uniform pattern is independent on the number of trees and $\frac{\pi }{4}$ times the plot area. (3) If a tree is removed, the area of some trees’ monopolized circle will increase without decreasing the monopolized circles of the other trees. According to the above three characteristics, “uniform index” is defined as the total area of monopolized circles in a plot divided by the total area of the monopolized circles, arranged in a uniform pattern in the same shaped plot. According to the definition of monopolized circle, the distribution of uniform index $(L) = \frac{{\chi ^2 (2n)}}{{2\pi n}}$ for a random pattern and $E(L) = \frac{1}{\pi }$ the variance of L is $D(L) = \frac{1}{{n\pi ^2 }}$ . It is evident that E(L) is independent on N and the plot area; hence, L is a relative index. L can be used to compare the uniformity among plots with different areas and the numbers of trees. In a random pattern, where L is equivalent to the tree density of the plot in which the number of trees is 1 and the area is π, the influence of tree number and plot area to L is eliminated. When n→∞, D(L)→0 and $L \to \frac{1}{\pi } = 0.318$ it indicates that the greater the number of tree is in the plots, the smaller the difference between the uniform indices will be. There are three types of patterns for describing tree distribution (aggregated, random, and uniform patterns). Since the distribution of L in the random pattern is accurately derived, L can be used to test the pattern types. The research on Moarshan showed that the whole plot has an aggregated pattern; the first, third, and sixth parts have an aggregated pattern; and the second, fourth, and fifth parts have a random pattern. None of the uniform indices is more than 0.318 (1/∏), which indicates that uniform patterns are rare in natural forests. The rules of uniform index can be applied to forest thinning. If you want to increase the value of uniform index, you must increase the total area of monopolized circles, which can be done by removing select trees. “Increasing area trees” are the removed trees and can increase the value of the uniform index. A tree is an increasing area tree if the distance between the tree and its second nearest neighbor is $\sqrt 2 $ times longer than that between the tree itself and its first nearest neighbor, which is called the $\sqrt 2 $ rule. It was very interesting to find that when six plots were randomly separated from the original plot, the proportion of increasing area trees in each plot was always about 0.5 without exception. In random pattern, the expected proportion of increasing area trees is about 0.35–0.44, which is different from the sampling value of 0.5. The reason is very difficult to explain, and further study is needed. Two criteria can be used to identify which trees should be removed to increase the uniform index during forest thinning. Those trees should be (1) trees whose monopolized circle areas are on the small side and (2) increasing area trees, which are found via the $\sqrt 2 $ rule.     

Genetic parameters and provenance variation of Pinus radiata D. Don. ‘Eldridge collection’ in Australia 2: wood properties

Provenance variation and genetic parameters for wood properties of mature radiata pine (Pinus radiata D. Don) were studied by sampling three provenance/progeny trials in southeast Australia. Among the mainland provenances, Monterey and Año Nuevo had higher density and modulus of elasticity (at one site) than Cambria. Basic density and predicted modulus of elasticity (MoE) for the island provenances, Guadalupe and Cedros, were ～20% higher at Billapaloola compared to mainland provenances grown at Green Hills and Salicki, differences that may or may not be linked to site differences. Heritability estimates of density, predicted MoE and microfibril angle were significant and $ {\bar{h}^2} $ ?>?0.45, suggesting moderate to strong genetic control. The estimated genetic correlations between diameter at breast height and wood properties in the current study were weaker (less negative) than the mean estimated from the current breeding population generation in radiata pine. Of the wood properties, density showed the strongest adverse genetic correlations with growth (mean r _A ?=??0.23?±?0.09). Selection for MoE may produce greater gain than selection for density because MoE had almost twice the estimated additive genetic coefficient of variation ( $ {\overline {\text{CV}}_A} $ ) compared to density. Estimated type B genetic correlations (r _B) for all wood quality traits were typically high, conforming to the trend that wood properties have low genotype-by-environment interaction (G?×?E). Significant differences in wood properties among provenances, families and/or individual trees provide an opportunity for breeding programmes to select superior trees for solid wood production that will combine superior growth with desirable wood traits.     

Heritability for resistance to Puccinia psidii Winter rust in Eucalyptus grandis Hill ex Maiden in Southwestern Brazil

The climates of the central and southern regions of São Paulo state in Brazil favor pathogens such as Puccinia psidii Winter, which causes a common and severe disease in Eucalyptus plantations under 2 years old. We studied genetic parameters including genotype by environment interaction (G × E) of resistance to P. psidii rust in Eucalyptus grandis at nine sites in São Paulo State. Open-pollinated progeny from ten ‘provenances’ were established in a randomized complete block design; at individual sites there were from 134 to 160 progenies, from four to eight blocks, and five to six trees per plot. Significant provenance and progeny(provenance) differences were detected, as was G × E involving progeny(provenance). However, the G × E involved little if any rank changes, indicating that selection can be done efficiently at a single site, if the disease level is sufficient. The estimated coefficient of genetic variation among the progeny within provenances $ \left( {{{{\widehat{\mathrm{CV}}}}_{\mathrm{g}}}} \right) $ was high and variable among the sites (ranging from 11 % to 36.7 %), demonstrating different expression of genetic variability among the sites. The estimated heritability at the individual-tree level $ \left( {{{\widehat{h}}^2}} \right) $ and within a plot $ \left( {\widehat{h}_{\mathrm{w}}^2} \right) $ ranged from low to intermediate (ranging from 0.04 to 0.46) and was high at the progeny-mean level $ \left( {\widehat{h}_{\mathrm{f}}^2} \right) $ (ranging from 0.30 to 0.86). Our study shows good prospects of controlling this disease by selection among and within progenies in a single site.     

Deriving fluorometer-specific values of relative PSI fluorescence intensity from quenching of F 0 fluorescence in leaves of Arabidopsis thaliana and Zea mays

The effect of stepwise increments of red light intensities on pulse-amplitude modulated (PAM) chlorophyll (Chl) fluorescence from leaves of A. thaliana and Z. mays was investigated. Minimum and maximum fluorescence were measured before illumination (F ₀ and F _M, respectively) and at the end of each light step ( $ F^{\prime}_{0} $ and $ F^{\prime}_{\text{M}} $ , respectively). Calculated $ F^{\prime}_{0} $ values derived from F ₀, F _M and $ F^{\prime}_{\text{M}} $ fluorescence according to Oxborough and Baker (1997) were lower than the corresponding measured $ F^{\prime}_{0} $ values. Based on the concept that calculated $ F^{\prime}_{0} $ values are under-estimated because the underlying theory ignores PSI fluorescence, a method was devised to gain relative PSI fluorescence intensities from differences between calculated and measured $ F^{\prime}_{0} $ . This method yields fluorometer-specific PSI data as its input data (F ₀, F _M, $ F^{\prime}_{0} $ and $ F^{\prime}_{\text{M}} $ ) depend solely on the spectral properties of the fluorometer used. Under the present conditions, the PSI contribution to F ₀ fluorescence was 0.24 in A. thaliana and it was independent on the light acclimation status; the corresponding value was 0.50 in Z. mays. Correction for PSI fluorescence affected Z. mays most: the linear relationship between PSI and PSII photochemical yields was clearly shifted toward the one-to-one proportionality line and maximum electron transport was increased by 50 %. Further, correction for PSI fluorescence increased the PSII reaction center-specific parameter, 1/F ₀ ? 1/F _M, up to 50 % in A. thaliana and up to 400 % in Z. mays.     

Provenance variation and genetic parameters of Eucalyptus viminalis in Argentina

Genetic parameters for growth, stem straightness, pilodyn penetration, relative bark thickness and survival were estimated in a base-population of five open-pollinated provenance/progeny trials of Eucalyptus viminalis. The trials, located in northern, central and southern Buenos Aires Province, Argentina, comprised 148 open-pollinated families from 13 Australian native provenances and eight local Argentinean seedlots. The Australian native provenances come from a limited range of the natural distribution. Overall survival, based on the latest assessment of each trial, was 62.4%. Single-site analyses showed that statistically significant provenances differences (p?<?0.05) for at least one of the studied traits in three out of the five trials analyzed. The local land race performed inconsistently in this study. The average narrow-sense individual-tree heritability estimate $ \left( {{{\hat{h}}^2}} \right) $ was 0.27 for diameter and 0.17 for total height. Values of $ {\hat{h}^2} $ also increased with age. Pilodyn penetration, assessed at only one site, was more heritable $ \left( {{{\hat{h}}^2} = 0.32} \right) $ than the average of growth traits. Estimated individual-tree heritabilities were moderate to low for stem straightness (average of 0.20) and relative bark thickness (0.16). The estimated additive genetic correlations $ \left( {{{{r}}_{{A}}}} \right) $ between diameter and height were consistently high and positive ( $ {{r}_{^A}} $ average of 0.90). High additive genetic correlations were observed between growth variables and pilodyn penetration ( $ {{r}_{^A}} $ average of 0.58). Relative bark thickness showed a negative correlation with diameter $ \left( {{{{r}}_{^A}} = - 0.39} \right) $ and height $ \left( {{{{r}}_{^A}} = - 0.51} \right) $ . The average estimated additive genetic correlation between sites was high for diameter (0.67). The implications of all these parameter estimates for genetic improvement of E. viminalis in Argentina are discussed.     

Investigation of the possibility of exceeding the Greenwald density limit during ECRH in T-10

In T-10 experiments, attempts were made to significantly exceed the Greenwald limit $\bar n_{Gr} $ during high-power (P _ab=750 kW) electron-cyclotron resonance heating (ECRH) and gas puffing. Formally, the density limit $(\bar n_e )_{\lim } $ exceeding the Greenwald limit $({{(\bar n_e )_{\lim } } \mathord{\left/ {\vphantom {{(\bar n_e )_{\lim } } {\bar n_{Gr} }}} \right. \kern-0em} {\bar n_{Gr} }} = 1.8)$ was achieved for q _L=8.2. However, as q _L decreased, the ratio ${{(\bar n_e )_{\lim } } \mathord{\left/ {\vphantom {{(\bar n_e )_{\lim } } {\bar n_{Gr} }}} \right. \kern-0em} {\bar n_{Gr} }}$ also decreased, approaching unity at q _L≈3. It was suggested that the “current radius” (i.e., the radius of the magnetic surface enclosing the bulk of the plasma current I _p), rather than the limiter radius, was the parameter governing the value of $(\bar n_e )_{\lim } $ . In the ECRH experiments, no substantial degradation of plasma confinement was observed up to $\bar n_e \sim 0.9(\bar n_e )_{\lim } $ regardless of the ratio ${{(\bar n_e )_{\lim } } \mathord{\left/ {\vphantom {{(\bar n_e )_{\lim } } {\bar n_{Gr} }}} \right. \kern-0em} {\bar n_{Gr} }}$ . In different scenarios of the density growth up to $(\bar n_e )_{\lim } $ , two types of disruptions related to the density limit were observed.     

Estimation of viscosity from passage time of liquids flowing through a microchannel array

Recently, a microchannel flow analyzer (MC-FAN) has been used to study the flow properties of blood. However, the correlation between blood passage time measured by use of the MC-FAN and hemorheology has not been clarified. In this study, a simple model is proposed for estimation of liquid viscosity from the passage time t _p of liquids. The t _p data for physiological saline were well represented by the model. According to the model, the viscosity of Newtonian fluids was estimated reasonably well from the t _p data. For blood samples, although the viscosity $ \eta_{\text{mc}} $ estimated from t _p was shown to be smaller than the viscosity $ \eta_{{450{\text{s}}^{ - 1} }} $ measured by use of a rotatory viscometer at a shear rate of 450 s^?1, $ \eta_{\text{mc}} $ was correlated with $ \eta_{{450{\text{s}}^{ - 1} }} $ . An empirical equation for estimation of $ \eta_{{450{\text{s}}^{ - 1} }} $ from $ \eta_{\text{mc}} $ of blood samples is proposed.     

Counting glycans revisited

We present an algorithm for counting glycan topologies of order \(n\) that improves on previously described algorithms by a factor \(n\) in both time and space. More generally, we provide such an algorithm for counting rooted or unrooted \(d\) -ary trees with labels or masses assigned to the vertices, and we give a “recipe” to estimate the asymptotic growth of the resulting sequences. We provide constants for the asymptotic growth of \(d\) -ary trees and labeled quaternary trees (glycan topologies). Finally, we show how a classical result from enumeration theory can be used to count glycan structures where edges are labeled by bond types. Our method also improves time bounds for counting alkanes.     

Impact of monoecy in the genetic structure of a predominately dioecious conifer species, Araucaria angustifolia (Bert.) O. Kuntze

Understanding the mating system of a tree species is important in genetic conservation and tree breeding strategies because it affects the inbreeding and genetic diversity of the descendant populations. Araucaria angustifolia (Bert.) O. Kuntze is a mainly dioecious species that reproduces through outcrossing. However, some monoecious trees have been identified and they may reproduce through self-fertilization. The objective of this study was to confirm the expected relatedness of full-sibs in outcrossed hand-pollinated progenies of female seed trees, self-sibs of hand self-pollinated monoecious seed trees, and to investigate the mating system of open-pollinated progenies of female and monoecious A. angustifolia trees. To do this, eight microsatellite loci were used to genotype hand- and open-pollinated progenies. Our results show that the relatedness of outcrossed hand-pollinated progenies are true full-sibs and progenies from a selfed monoecious seed tree are self-sibs, which confirms the hand-pollination method used. Open-pollinated female seed trees reproduced only by outcrossing, generating progenies with a mixture of full- and half-sibs. Monoecious seed trees reproduced mainly by xenogamy, generating progenies with mixtures of self-sibs, full-sibs, half-sibs and self-half-sibs. We also found that an increase in the effective number of pollen donors ( $ N_{\text{ep}} $ ) would lead to an increase in the total number of alleles ( $ K $ ) within progenies. Our results also suggest that monecious trees have limited potential to modify the genetic structure through selfed seed production due to the very low estimated selfing rate in these trees and the rare occurrence of these trees in natural populations.     

Pareto genealogies arising from a Poisson branching evolution model with selection

We study a class of coalescents derived from a sampling procedure out of $N$ i.i.d. Pareto $\left( \alpha \right) $ random variables, normalized by their sum, including $\beta $ –size-biasing on total length effects ( $\beta <\alpha $ ). Depending on the range of $\alpha ,$ we derive the large $N$ limit coalescents structure, leading either to a discrete-time Poisson-Dirichlet $ \left(\alpha ,-\beta \right) \Xi -$ coalescent ( $\alpha \in \left[ 0,1\right) $ ), or to a family of continuous-time Beta $\left( 2-\alpha ,\alpha -\beta \right) \Lambda -$ coalescents ( $\alpha \in \left[ 1,2\right) $ ), or to the Kingman coalescent ( $\alpha \ge 2$ ). We indicate that this class of coalescent processes (and their scaling limits) may be viewed as the genealogical processes of some forward in time evolving branching population models including selection effects. In such constant-size population models, the reproduction step, which is based on a fitness-dependent Poisson Point Process with scaling power-law $\left( \alpha \right) $ intensity, is coupled to a selection step consisting of sorting out the $N$ fittest individuals issued from the reproduction step.     

Bayesian estimation of genetic parameters for growth,stem straightness,and survival in Eucalyptus globulus on an Andean Foothill site

Knowledge of the genetic variation of key economic traits in Eucalyptus globulus under cold conditions is crucial to the genetic improvement of environmental tolerances and other economic traits. A Bayesian analysis of genetic parameters for quantitative traits was carried out in 37 E. globulus open-pollinated families under cold conditions in southern Chile. The trial is located in the Andean foothills, in the Province of Bío-Bío. The Bayesian approach was performed using Gibbs sampling algorithm. Multi-trait linear and threshold models were fitted to phenotypic data (growth traits, survival, and stem straightness). Fifteen years after planting, height, diameter at breast height, and stem volume were found to be weakly to moderately heritable with Bayesian credible intervals (probability of 90 %): $ {\widehat{h}}^2 $ ?=?0.009–0.102, $ {\widehat{h}}^2 $ ?=?0.031–0.185, and $ {\widehat{h}}^2 $ ?=?0.045–0.205, respectively. Stem straightness was found to be weakly to moderately heritable ranging from 0.032 to 0.208 (Bayesian 90 % credible interval); posterior mode $ {\widehat{h}}^2 $ ?=?0.091. Tree survival at age of 15 years was high in the trial (84.8 %) with such heritability values ranging from 0.072 to 0.157. Survival was non-significantly genetically correlated to growth and stem straightness. Stem volume had the highest predicted genetic gains ranging from 17.9 to 23.7 % (selection rate of 15.8 and 8.3 %, respectively). The results of this study confirm the potential for selective breeding of this eucalypt in areas of southern Chile where cold is a significant constraint.     

Hyperfine interactions and electron distribution in FeIIFeI and FeIFeI models for the active site of the [FeFe] hydrogenases: Mössbauer spectroscopy studies of low-spin FeI

Mössbauer studies of [{μ-S(CH₂C(CH₃)₂CH₂S}(μ-CO)Fe^IIFe^I(PMe₃)₂(CO)₃]PF₆ (1 _OX ), a model complex for the oxidized state of the [FeFe] hydrogenases, and the parent Fe^IFe^I derivative are reported. The paramagnetic 1 _OX is part of a series featuring a dimethylpropanedithiolate bridge, introducing steric hindrance with profound impact on the electronic structure of the diiron complex. Well-resolved spectra of 1 _OX allow determination of the magnetic hyperfine couplings for the low-spin distal Fe^I ( $ {\text{Fe}}^{\text{I}} _{\text{ D}} $ Fe D I ) site, A _x,y,z  = [?24 (6), ?12 (2), 20 (2)] MHz, and the detection of significant internal fields (approximately 2.3 T) at the low-spin ferrous site, confirmed by density functional theory (DFT) calculations. Mössbauer spectra of 1 _OX show nonequivalent sites and no evidence of delocalization up to 200 K. Insight from the experimental hyperfine tensors of the Fe^I site is used in correlation with DFT to reveal the spatial distribution of metal orbitals. The Fe–Fe bond in [Fe₂{μ-S(CH₂C(CH₃)₂CH₂S}(PMe₃)₂(CO)₄] (1) involving two $ d_{{z^{2} }} $ d z 2 -type orbitals is crucial in keeping the structure intact in the presence of strain. On oxidation, the distal iron site is not restricted by the Fe–Fe bond, and thus the more stable isomer results from inversion of the square pyramid, rotating the $ d_{{z^{2} }} $ d z 2 orbital of $ {\text{Fe}}^{\text{I}} _{\text{ D}} $ Fe D I . DFT calculations imply that the Mössbauer properties can be traced to this $ d_{{z^{2} }} $ d z 2 orbital. The structure of the magnetic hyperfine coupling tensor, A, of the low-spin Fe^I in 1 _OX is discussed in the context of the known A tensors for the oxidized states of the [FeFe] hydrogenases.     

Quantitative Genetics and Modularity in Cranial and Mandibular Morphology of Calomys expulsus

Patterns of genetic covariance between characters (represented by the covariance matrix \({\varvec{G}}\) ) play an important role in morphological evolution, since they interact with the evolutionary forces acting over populations. They are also expected to influence the patterns expressed in their phenotypic counterparts \(({\varvec{P}})\) , because of limits imposed by multiple developmental and functional restrictions on the genotype/phenotype map. We have investigated genetic covariances in the skull and mandible of the vesper mouse (Calomys expulsus) in order to estimate the degree of similarity between genetic and phenotypic covariances and its potential roots on developmental and functional factors shaping those integration patterns. We use a classic ad hoc analysis of morphological integration based on current state of art of developmental/functional factors during mammalian ontogeny and also applied a novel methodology that makes use of simulated evolutionary responses. We have obtained \({\varvec{P}}\) and \({\varvec{G}}\) that are strongly similar, for both skull and mandible; their similarity is achieved through the spatial and temporal organization of developmental and functional interactions, which are consistently recognized as hypothesis of trait associations in both matrices.     

Quantifying the risk of mis-estimating correlation significance of climate–tree growth relationships

In dendroecology, sampling effort has a strong influence of both regional chronology properties and climate–tree growth relationships assessment. Recent studies evidenced that decreasing sample size leads to a weakening of the bootstrapped correlation coefficients ( ${\text{BCC}}$ BCC ). The present analysis focused on the risk of mis-estimating the significance of population ${\text{BCC}}\,\left( {{\text{BCC}}_{\text{POP}} } \right)$ BCC ( BCC POP ) from a sample of N trees, and then proposed an approach to detect and correct mis-estimations using the properties of the sample. The sample size effect and the limits of the correction were illustrated from 840 individual growth chronologies of Corsican pine (Pinus nigra Arnold ssp. laricio Poiret var. Corsicana) sampled in Western France. The 840 trees were used to assess the population characteristics, and the effect of sampling effort was investigated through a simulation approach based on a resampling procedure of N trees amongst 840 (N ? [5; 50]). Our results evidenced that the risk strongly varied amongst the climatic regressors. The highest risks were evidenced for significant ${\text{BCC}}_{\text{POP}}$ BCC POP , with a percentage of mis-estimation ranging from 25 to 80. On the contrary, small samples allowed providing an reliable estimation of the significance of non-significant ${\text{BCC}}_{\text{POP}}$ BCC POP . To a lesser extent, the risk slightly decreased with increasing N, according to a negative exponential trend. The detection and correction method was found relevant to detect mis-estimation only for significant ${\text{BCC}}_{\text{POP}}$ BCC POP ; otherwise, the ${\text{BCC}}_{\text{POP}}$ BCC POP significance was generally overestimated.     

Proton cycles through membranes in bacteria: Relationship between proton passive and active fluxes and their dependence on some external physico-chemical factors under fermentation

This paper represents H⁺ circles through the bacterial membranes, their peculiarities and relationship with ATP synthesis or hydrolysis, utilization or accumulation of energy are considered. Data on passive and active proton (H⁺) fluxes through the bacterial membranes are analyzed and their relationship with membrane H⁺ conductance $\left( {G_m^{H^ + } } \right)$ and permeability for H⁺ $\left( {P_{H^ + } } \right)$ is discussed. Methods for determination of bacterial membrane $G_m^{H^ + }$ are presented and some difficulties in obtaining and interpreting data are pointed out. Different ways and mechanisms of passive and active H⁺ fluxes, including a role of membrane lipids in H⁺ transfer, importance of phase transitions in lipid bilayers, operation of protonophores as well as H⁺ translocation via the F₀ factor of the F₀F₁-ATPase, are discussed. Dependence of $G_m^{H^ + }$ for Escherichia coli, Enterococcus hirae, Streptococcus lactis and other bacteria on some external physico-chemical growth factors, particularly, on pH and oxidation reduction potential as well as influence of osmotic stress on $G_m^{H^ + }$ and H⁺ active fluxes through the bacterial membrane under fermentation have been shown. The relationship between $G_m^{H^ + }$ , $P_{H^ + }$ and active H⁺ fluxes through a membrane is proposed, possible mechanisms of relationship between their alterations depending on pH and oxidation reduction potential are discussed. The results are important for understanding the structural and functional properties of bacterial membranes determining H⁺ cycles operation and mechanisms of H⁺ fluxes essential in adaptation of bacteria to altered environment conditions.     

Control of mitochondrial and cellular respiration by oxygen

Control and regulation of mitochondrial and cellular respiration by oxygen is discussed with three aims: (1) A review of intracellular oxygen levels and gradients, particularly in heart, emphasizes the dominance of extracellular oxygen gradients. Intracellular oxygen pressure, $p_{O_2 } $ , is low, typically one to two orders of magnitude below incubation conditions used routinely for the study of respiratory control in isolated mitochondria. The $p_{O_2 } $ range of respiratory control by oxygen overlaps with cellular oxygen profiles, indicating the significance of $p_{O_2 } $ in actual metabolic regulation. (2) A methodologically detailed discussion of high-resolution respirometry is necessary for the controversial topic of respiratory control by oxygen, since the risk of methodological artefact is closely connected with far-reaching theoretical implications. Instrumental and analytical errors may mask effects of energetic state and partially explain the divergent views on the regulatory role of intracellular $p_{O_2 } $ . Oxygen pressure for half-maximum respiration,p ₅₀, in isolated mitochondria at state 4 was 0.025 kPa (0.2 Torr; 0.3 ΜM O₂), whereasp ₅₀ in endothelial cells was 0.06–0.08 kPa (0.5 Torr). (3) A model derived from the thermodynamics of irreversible processes was developed which quantitatively accounts for near-hyperbolic flux/ $p_{O_2 } $ relations in isolated mitochondria. The apparentp ₅₀ is a function of redox potential and protonmotive force. The protonmotive force collapses after uncoupling and consequently causes a decrease inp ₅₀. Whereas it is becoming accepted that flux control is shared by several enzymes, insufficient attention is paid to the notion of complementary kinetic and thermodynamic flux control mechanisms.     

Synchronicity of movement paths of barren-ground caribou and tundra wolves

Movement patterns of highly mobile animals can reveal life history strategies and ecological relationships. We hypothesized that wolves (Canis lupus) would display similar movement patterns as their prey, barren-ground caribou (Rangifer tarandus groenlandicus), and that movements of the two species would co-vary with season. We tested for interspecific movement dynamics using animal locations from wolves and caribou monitored concurrently from mid-October to June, across the Northwest Territories and Nunavut, Canada. We used a correlated random walk as a null model to test for pattern in movements and the bearing procedure to detect whether movements were consistently directional. There was a statistical difference between the movements of caribou and wolves (F _1,9 = 13.232, P = 0.005), when compared to a correlated random walk, and a significant interaction effect between season and species (F _1,9 = 6.815, P = 0.028). During winter, the movements of caribou were strongly correlated with the 80°–90° ( $\overline{X}$ X ¯ r = 0.859, SE = 0.065) and 270°–280° ( $\overline{X}$ X ¯ r = 0.875, SE = 0.059) bearing classes suggesting an east–west movement gradient. Wolf movements during winter showed large variation in direction, but were generally east to west. Peak mean correlation for caribou movements during spring was distinct at 40°–50° ( $\overline{X}$ X ¯ r = 0.978, SE = 0.006) revealing movement to the north-east calving grounds. During spring, wolf movements correlated with the 80°–90° ( $\overline{X}$ X ¯ r = 0.861, SE = 0.043) and 270°–280° ( $\overline{X}$ X ¯ r = 0.850, SE = 0.064) bearing class. Directionality of movement suggested that during winter, caribou and wolves had a similar distribution at the large spatial scales we tested. During spring migration, however, caribou and wolves employed asynchronous movement strategies. Our findings demonstrate the utility of the correlated random walk and bearing procedure for quantifying the movement patterns of co-occurring species.     

Quantifying interspecific spatial overlap in aquatic macrophyte communities

Levins’s asymmetrical α index quantifies between species overlap over resources more realistically than similar-purpose single-value indices. The associated community-wide \(\bar \alpha\) index expresses the degree of “species packing”. Both indices were formulated upon competing animal (i.e., mobile) organisms and are independent of population densities. However, overlap over resources for nonmobile organisms such as plants may have an impact even below carrying capacity. The proposed \(\hat \alpha\) index, based on Levins’s α index, quantifies spatial overlap for plants integrating information on species spatial distribution and crowding conditions. The \(\hat \alpha\) index is specifically designed for plant distribution data collected in discrete plots with density expressed as percent coverage (%cover) of substratum. We also propose a community-wide \({\hat \alpha_{\text{c}}}\) index, conceptually analogous to \(\bar \alpha\) , but furnished with a measure of dispersion (se \({\hat \alpha_{\text{c}}}\) ). Species importance within the community is inferred from comparisons of pairwise \(\hat \alpha\) ’s with \({\hat \alpha_{\text{c}}}\) . The \(\hat \alpha\) and \({\hat \alpha_{\text{c}}}\) indices correlate closely and exponentially with plant density, and correct apparent over- and underestimations of interaction intensity at low and very high crowding by Levins’s α and \(\bar \alpha\) , respectively. Index application to aquatic plant communities gave results consistent with within-community and general ecological patterns, suggesting a high potential of the proposed \(\hat \alpha\) and \({\hat \alpha_{\text{c}}}\) indices in basic and applied macrophyte ecological studies and management.     

Kinetic models of coupling between H+ and Na+-translocation and ATP synthesis/hydrolysis by F0F1-ATPases: Can a cell utilize both\Delta \bar \mu _{H^ + } and\Delta \bar \mu _{Na^ + } for ATP synthesis underin vivo conditions using the same enzyme?

Kinetic models of the F₀F₁-ATPase able to transport H⁺ or/and Na⁺ ions are proposed. It is assumed that (i) H⁺ and Na⁺ compete for the same binding sites, (ii) ion translocation through F₀ is coupled to the rate-limiting step of the F₁-catalyzed reaction. The main characteristics of the dependences of ATP synthesis and hydrolysis rates on Δφ, ΔpH, and ΔpNa are predicted for various versions of the coupling model. The mechanism of the switchover from \(\Delta \bar \mu _{H^ + } \) -dependent synthesis to the \(\Delta \bar \mu _{Na^ + } \) -dependent one is demonstrated. It is shown that even with a drastic drop in \(\Delta \bar \mu _{H^ + } \) , ATP hydrolysis by the proton mode of catalysis can be effectively inhibited by Δφ and ΔpNa. The results obtained strongly support the possibility that the same F₀F₁-ATPase in bacterial cells can utilize both \(\Delta \bar \mu _{H^ + } \) and \(\Delta \bar \mu _{Na^ + } \) for ATP synthesis underin vivo conditions.