Ponderomotive Self-focusing of Surface Plasma Wave

A large amplitude surface plasma wave (SPW) propagating over a conductor–vaccum interface with Gaussian intensity profile transverse to the direction of propagation ( $ \widehat{z} $ ) and surface normal ( $ \widehat{x} $ ) is shown to undergo periodic self-focusing due to ponderomotive nonlinearity. The ponderomotive force on electrons arises due to the rapid decline in surface wave amplitude with the depth inside the conductor. In case of plasma, this leads to ambipolar diffusion of plasma, whereas in metals, only electron displacement occurs until the space charge balances the ponderomotive force on electrons. For a surface plasma wave, having Gaussian amplitude profile in y, the maximum electron density depression occurs on the axis (y?=?0) and the effect weakens as |y| increases. The axial portion of SPW thus travels with slower phase velocity than the nonaxial portion leading to self-focusing.     

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.     

Can the positive aromatic ring be as ��-electron donor in ��-halogen bond? A MP2 theoretical investigation on the unusual ��-halogen bond interaction between three-membered ring \left( {\hbox{BNN}} \right)_3^{+} and X1X2 (X1, X2?=?F, Cl, Br)

The unusual ??-halogen bond interactions are investigated between $ \left( {\hbox{BNN}} \right)_3^{+} $ and X1X2 (X1, X2?=?F, Cl, Br) employing MP2 at 6-311?+?G(2d) and aug-cc-pVDZ levels according to the ??CP (counterpoise) corrected potential energy surface (PES)?? method. The order of the ??-halogen bond interactions and stabilities of the complexes are obtained to be $ \left( {\hbox{BNN}} \right)_3^{+} \ldots {{\hbox{F}}_2} < \left( {\hbox{BNN}} \right)_3^{+} \ldots {\hbox{ClF < }}\left( {\hbox{BNN}} \right)_3^{+} \ldots {\hbox{C}}{{\hbox{l}}_2} < \left( {\hbox{BNN}} \right)_3^{+} \ldots {\hbox{BrCl}}\quad { < }\quad \left( {\hbox{BNN}} \right)_3^{+} \ldots {\hbox{B}}{{\hbox{r}}_2}\quad { < }\quad \left( {\hbox{BNN}} \right)_3^{+} \ldots {\hbox{BrF}}{.} $ at MP2/aug-cc-pVDZ level. The analyses of the Mulliken charge transfer, natural bond orbital (NBO), atoms in molecules (AIM) theory and electron density shifts reveal that the nature of the ??-halogen bond interaction in the complexes of ClF, BrF and BrCl might partly be charge transfer from the delocalized ??-HOMO orbital of $ \left( {\hbox{BNN}} \right)_3^{+} $ to X1X2. This result suggests that the positive aromatic ring $ \left( {\hbox{BNN}} \right)_3^{+} $ might act as a ??-electron donor to form the ??-halogen bond.

On the page number of RNA secondary structures with pseudoknots

Let ${\mathcal {S}}$ denote the set of (possibly noncanonical) base pairs {i, j} of an RNA tertiary structure; i.e. ${\{i, j\} \in \mathcal {S}}$ if there is a hydrogen bond between the ith and jth nucleotide. The page number of ${\mathcal {S}}$ , denoted ${\pi(\mathcal {S})}$ , is the minimum number k such that ${\mathcal {S}}$ can be decomposed into a disjoint union of k secondary structures. Here, we show that computing the page number is NP-complete; we describe an exact computation of page number, using constraint programming, and determine the page number of a collection of RNA tertiary structures, for which the topological genus is known. We describe an approximation algorithm from which it follows that ${\omega(\mathcal {S}) \leq \pi(\mathcal {S}) \leq \omega(\mathcal {S}) \cdot \log n}$ , where the clique number of ${\mathcal {S}, \omega(\mathcal {S})}$ , denotes the maximum number of base pairs that pairwise cross each other.     

Obtain Quadruple Intense Plasmonic Resonances from Multilayered Gold Nanoshells by Silver Coating: Application in Multiplex Sensing

Four intense and separate localized surface plasmon resonance (LSPR) absorption peaks have been obtained in the gold-dielectric–gold–silver multilayer nanoshells. The silver coating on the gold shell results in a new LSPR peak at about 400 nm corresponding to the $ {{\left| {\omega_{+}^{-}} \right\rangle}_{Ag }} $ mode. The intense local electric field concentrated in the silver shell at the wavelength of 400 nm indicates that this new plasmonic band is coming from the symmetric coupling between the antibonding silver shell plasmon mode and the inner sphere plasmon. Increasing the silver shell thickness also leads to the intensity increasing of the $ {{\left| {\omega_{+}^{-}} \right\rangle}_{Au }} $ mode and blue shift of $ \left| {\omega_{-}^{+}} \right\rangle $ and $ \left| {\omega_{-}^{-}} \right\rangle $ modes. Therefore, quadruple intense plasmonic resonances in the visible region could be achieved in gold-dielectric–gold–silver multilayer nanoshells by tuning the geometrical parameters. And the quadruple intense plasmonic resonances in the visible region provide well potential for multiplex biosensing based on LSPR.     

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.     

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.     

Sur l'espace topologique lié à une nouvelle théorie de l'apprentissage

There have been two contrasting doctrines concerning learning, more generally about acquisition of knowledge: empiricism and rationalism. The theory of learning in such a field as artificial intelligence seems to fall within the empiricist framework. On the hand, N. Chomsky and his followers have discussed, during the last decade, concerning learning, especially about language learning, from the rationalist point of view (Chomsky, 1965). The main feature in the rationalist approach toward a theory of learning lies in the speculation that in order to acquire knowledge it is indispensable for a learner to be endowed with “innate ideas”, and that “experience” in the external world are merely subsidiary types of information for the learner. If this is acceptable, we can inquire: Under what kind of innate ideas can the learner understand the structure of the external world? In our previous paper (Uesaka, Aizawa, Ebara, and Ozeki, 1973), we formalized this by introducing the mathematical notion of “learnability”, and gave a partial answer to the above inquiry. In this formalization we assumed that the set F of objects to be learned consists of mappings of N to itself, where N is the set of positive integers. Then, constructing a topological space (F, \(\mathcal{O}\) ) by an appropriate family \(\mathcal{O}\) of open sets, we observed that the notion of learnability can be well described in terms of topological properties of the learning space (F, \(\mathcal{O}\) ). Many problems must be solved, however, before we raise the theory to a complete model of the rationalist theory of learning. The topological study of the space (F, \(\mathcal{O}\) ) is, we believe, the first step toward this approach. In this context, we discuss the topological aspects of this space. Now we define \(\mathcal{O}\) as follows: By N ² we mean the direct product of two N's. Let s be a subset of N ². If, for any (x, y), (x′, y′) in s, x=x′ implies y=y′, then we say that s is single-valued. Let f ∈ F, If, for any (x, y) in s, y=f(x), then f is said to be on s, denoted as \(f\underline \supseteq s\) . Let \(\pi \left( s \right) = \left\{ {g;g \in F,g\underline \supseteq s} \right\}\) . A single-valued finite subset of N ² is called datum. Let D denote the family of all data. Let \(\mathcal{O}* = \left\{ \phi \right\} \cup \left\{ {\pi \left( d \right);d \in D} \right\}\) , and \(\mathcal{O}\) denote the family of all subsets of F, each of which is written as \(\mathop \cup \limits_\alpha W_{\alpha }\) , where W _α is in \(\mathcal{O}*\) . Then, it is easily seen that \(\mathcal{O}\) satisfies the axiom of the open system of a topological space. It is shown that the learning space (F, \(\mathcal{O}\) ) has the following properties:

1. It satisfies the first and the second countability axioms.
2. It is separable and is totally disconnected.
3. It is a Hausdorff space and, further, is regular and normal.
4. It is neither compact nor locally compact.
5. It is metrizable, or more precisely there exists a complete but not totally bounded metric space which is homeomorphic to learning space.
6. Any of its subspace can be embedded into its special subspace.

     

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.     

The average local ionization energy as a tool for identifying reactive sites on defect-containing model graphene systems

In a continuing effort to further explore the use of the average local ionization energy $ \overline{\mathrm{I}}\left( \mathbf{r} \right) $ as a computational tool, we have investigated how well $ \overline{\mathrm{I}}\left( \mathbf{r} \right) $ computed on molecular surfaces serves as a predictive tool for identifying the sites of the more reactive electrons in several nonplanar defect-containing model graphene systems, each containing one or more pentagons. They include corannulene (C₂₀H₁₀), two inverse Stone-Thrower-Wales defect-containing structures C₂₆H₁₂ and C₄₂H₁₆, and a nanotube cap model C₂₂H₆, whose end is formed by three fused pentagons. Coronene (C₂₄H₁₂) has been included as a reference planar defect-free graphene model. We have optimized the structures of these systems as well as several monohydrogenated derivatives at the B3PW91/6-31G* level, and have computed their $ \overline{\mathrm{I}}\left( \mathbf{r} \right) $ on molecular surfaces corresponding to the 0.001 au, 0.003 au and 0.005 au contours of the electronic density. We find that (1) the convex sides of the interior carbons of the nonplanar models are more reactive than the concave sides, and (2) the magnitudes of the lowest $ \overline{\mathrm{I}}\left( \mathbf{r} \right) $ surface minima (the $ {{\overline{\mathrm{I}}}_{{\mathrm{S}\text{,}\min }}} $ ) correlate well with the interaction energies for hydrogenation at these sites. These $ {{\overline{\mathrm{I}}}_{{\mathrm{S}\text{,}\min }}} $ values decrease in magnitude as the nonplanarity of the site increases, consistent with earlier studies. A practical benefit of the use of $ \overline{\mathrm{I}}\left( \mathbf{r} \right) $ is that a single calculation suffices to characterize the numerous sites on a large molecular system, such as graphene and defect-containing graphene models.

Stochastic population growth in spatially heterogeneous environments

Classical ecological theory predicts that environmental stochasticity increases extinction risk by reducing the average per-capita growth rate of populations. For sedentary populations in a spatially homogeneous yet temporally variable environment, a simple model of population growth is a stochastic differential equation dZ _t = μ Z _t dt + σ Z _t dW _t , t ≥ 0, where the conditional law of Z _t+Δt ? Z _t given Z _t = z has mean and variance approximately z μΔt and z ² σ ²Δt when the time increment Δt is small. The long-term stochastic growth rate ${\lim_{t \to \infty} t^{-1}\log Z_t}$ for such a population equals ${\mu -\frac{\sigma^2}{2}}$ . Most populations, however, experience spatial as well as temporal variability. To understand the interactive effects of environmental stochasticity, spatial heterogeneity, and dispersal on population growth, we study an analogous model ${{\bf X}_t = (X_t^1, \ldots, X_t^n)}$ , t ≥ 0, for the population abundances in n patches: the conditional law of X _t+Δt given X _t = x is such that the conditional mean of ${X_{t+\Delta t}^i - X_t^i}$ is approximately ${[x^i \mu_i + \sum_j (x^j D_{ji} - x^i D_{ij})] \Delta t}$ where μ _i is the per capita growth rate in the ith patch and D _ij is the dispersal rate from the ith patch to the jth patch, and the conditional covariance of ${X_{t+\Delta t}^i - X_t^i}$ and ${X_{t + \Delta t}^j - X_t^j}$ is approximately x ⁱ x ^j σ _ij Δt for some covariance matrix Σ = (σ _ij ). We show for such a spatially extended population that if ${S_t = X_t^1 + \cdots + X_t^n}$ denotes the total population abundance, then Y _t = X _t /S _t , the vector of patch proportions, converges in law to a random vector Y _∞ as ${t \to \infty}$ , and the stochastic growth rate ${\lim_{t \to \infty} t^{-1}\log S_t}$ equals the space-time average per-capita growth rate ${\sum_i \mu_i \mathbb{E}[Y_\infty^i]}$ experienced by the population minus half of the space-time average temporal variation ${\mathbb{E}[\sum_{i,j}\sigma_{ij}Y_\infty^i Y_\infty^j]}$ experienced by the population. Using this characterization of the stochastic growth rate, we derive an explicit expression for the stochastic growth rate for populations living in two patches, determine which choices of the dispersal matrix D produce the maximal stochastic growth rate for a freely dispersing population, derive an analytic approximation of the stochastic growth rate for dispersal limited populations, and use group theoretic techniques to approximate the stochastic growth rate for populations living in multi-scale landscapes (e.g. insects on plants in meadows on islands). Our results provide fundamental insights into “ideal free” movement in the face of uncertainty, the persistence of coupled sink populations, the evolution of dispersal rates, and the single large or several small (SLOSS) debate in conservation biology. For example, our analysis implies that even in the absence of density-dependent feedbacks, ideal-free dispersers occupy multiple patches in spatially heterogeneous environments provided environmental fluctuations are sufficiently strong and sufficiently weakly correlated across space. In contrast, for diffusively dispersing populations living in similar environments, intermediate dispersal rates maximize their stochastic growth rate.     

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.     

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.     

The effects of temperature and exercise training on swimming performance in juvenile qingbo (Spinibarbus sinensis)

To investigate the effects of temperature and exercise training on swimming performance in juvenile qingbo (Spinibarbus sinensis), we measured the following: (1) the resting oxygen consumption rate $ \left( {{\dot{\text{M}}\text{O}}_{{ 2 {\text{rest}}}} } \right) $ , critical swimming speed (U _crit) and active oxygen consumption rate $ \left( {{\dot{\text{M}}\text{O}}_{{ 2 {\text{active}}}} } \right) $ of fish at acclimation temperatures of 10, 15, 20, 25 and 30 °C and (2) the $ \dot{M}{\text{O}}_{{ 2 {\text{rest}}}} $ , U _crit and $ \dot{M}{\text{O}}_{{ 2 {\text{active}}}} $ of both exercise-trained (exhaustive chasing training for 14 days) and control fish at both low and high acclimation temperatures (15 and 25 °C). The relationship between U _crit and temperature (T) approximately followed a bell-shaped curve as temperature increased: U _crit = 8.21/{1 + [(T ? 27.2)/17.0]²} (R ² = 0.915, P < 0.001, N = 40). The optimal temperature for maximal U _crit (8.21 BL s^?1) in juvenile qingbo was 27.2 °C. Both the $ \dot{M}{\text{O}}_{{ 2 {\text{active}}}} $ and the metabolic scope (MS, $ \dot{M}{\text{O}}_{{ 2 {\text{active}}}} - \dot{M}{\text{O}}_{{ 2 {\text{rest}}}} $ ) of qingbo increased with temperature from 10 to 25 °C (P < 0.05), but there were no significant differences between fish acclimated to 25 and 30 °C. The relationships between $ \dot{M}{\text{O}}_{{ 2 {\text{active}}}} $ or MS and temperature were described as $ {\dot{\text{M}}\text{O}}_{{ 2 {\text{active}}}} = 1,214.29/\left\{ {1 + \left[ {\left( {T - 28.8} \right)/10.6} \right]^{2} } \right\}\;\left( {R^{2} = 0.911,\;P < 0.001,\;N = 40} \right) $ and MS = 972.67/{1 + [(T ? 28.0)/9.34]²} (R ² = 0.878, P < 0.001, N = 40). The optimal temperatures for $ \dot{M}{\text{O}}_{{ 2 {\text{active}}}} $ and MS in juvenile qingbo were 28.8 and 28.0 °C, respectively. Exercise training resulted in significant increases in both U _crit and $ \dot{M}{\text{O}}_{{ 2 {\text{active}}}} $ at a low temperature (P < 0.05), but training exhibited no significant effect on either U _crit or $ \dot{M}{\text{O}}_{{ 2 {\text{active}}}} $ at a high temperature. These results suggest that exercise training had different effects on swimming performance at different temperatures. These differences may be related to changes in aerobic metabolic capability, arterial oxygen delivery, available dissolved oxygen, imbalances in ion fluxes and stimuli to remodel tissues with changes in temperature.     

Increased Damping of Plasmon Resonances in Gold Nanoparticles Due to Broadening of the Band Structure

For the first time, systematic investigations of the damping parameter A of gold nanoparticles as a function of photon energy are presented. A is an essential parameter that quantifies the size-dependent optical properties of metal nanoparticles in the dielectric function. To determine the damping parameter, the dephasing time T ₂ of gold nanoparticles has been systematically determined under ultrahigh vacuum conditions as a function of photon energy. Dephasing times ranging from  $T_2 = 5$ fs to $T_2 = 17$ fs were measured, and subsequently, the damping parameter has been extracted. We found a strong resonance-like damping of the plasmon resonance in the vicinity of the onset of the interband transition. While the damping parameter scatters statistically around a value of  $A = 0.19$ nm/fs for photon energies below  $h\nu = 1.70$ eV, it increases rapidly to 0.32 nm/fs for  $h\nu = 1.85$ eV. For higher photon energies, A decreases steadily to $A = 0.24$ nm/fs at $h\nu = 2.15$ eV. A comparison to former measurements as well as to theoretical predictions reveals surface scattering and a discretizing and broadening of the band structure that influences the interband transition as the most dominant size-dependent damping mechanisms. The latter, i.e., a damping via increased interband transitions, assumes a coherent damping process of the oscillating electrons and, as a consequence, the plasmon is treated as a two-level system. Thus, the results deliver new physical insight to the fundamental understanding of surface plasmons.     

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.     

A thermomechanical framework for reconciling the effects of ultraviolet radiation exposure time and wavelength on connective tissue elasticity

Augmentation of the mechanical properties of connective tissue using ultraviolet (UV) radiation—by targeting collagen cross-linking in the tissue at predetermined UV exposure time \((t)\) and wavelength \((\lambda )\) —has been proposed as a therapeutic method for supporting the treatment for structural-related injuries and pathologies. However, the effects of \(\lambda \) and \(t\) on the tissue elasticity, namely elastic modulus \((E)\) and modulus of resilience \((u_\mathrm{Y})\) , are not entirely clear. We present a thermomechanical framework to reconcile the \(t\) - and \(\lambda \) -related effects on \(E\) and \(u_\mathrm{Y}\) . The framework addresses (1) an energy transfer model to describe the dependence of the absorbed UV photon energy, \(\xi \) , per unit mass of the tissue on \(t\) and \(\lambda \) , (2) an intervening thermodynamic shear-related parameter, \(G\) , to quantify the extent of UV-induced cross-linking in the tissue, (3) a threshold model for the \(G\) versus \(\xi \) relationship, characterized by   \(t_\mathrm{C}\) —the critical \(t\) underpinning the association of \(\xi \) with \(G\) —and (4) the role of \(G\) in the tissue elasticity. We hypothesized that \(G\) regulates \(E\) (UV-stiffening hypothesis) and \(u_\mathrm{Y}\) (UV-resilience hypothesis). The framework was evaluated with the support from data derived from tensile testing on isolated ligament fascicles, treated with two levels of \(\lambda \) (365 and 254 nm) and three levels of \(t\) (15, 30 and 60 min). Predictions from the energy transfer model corroborated the findings from a two-factor analysis of variance of the effects of \(t\) and \(\lambda \) treatments. Student’s t test revealed positive change in \(E\) and \(u_\mathrm{Y}\) with increases in \(G\) —the findings lend support to the hypotheses, implicating the implicit dependence of UV-induced cross-links on \(t\) and \(\lambda \) for directing tissue stiffness and resilience. From a practical perspective, the study is a step in the direction to establish a UV irradiation treatment protocol for effective control of exogenous cross-linking in connective tissues.     

Capnographic parameters of the breathing pattern in healthy adults and patients with psychogenic dyspnea

Parameters of 5-min capnogram in 106 healthy humans (H group) were compared with those in 30 patients with psychogenic dyspnea (P group). Averaged values of end-tidal fractional concentration of carbon dioxide (FetCO₂) and respiration rate (f) were determined. The structure of the respiratory cycle was estimated by the ratio of the expiratory time to the total respiratory cycle time $\left( {R_{CO_2 } } \right)$ . The degree of breath arrhythmia was estimated using the coefficient of variation (CV) of $R_{CO_2 }$ , recorded during the 5-min capnography $\left( {R_{CO_2 } } \right)$ . The difference in the capnograms of H group and P group was reliable for all parameters, except for $R_{CO_2 }$ (structure of the respiratory cycle). For H group, FetCO₂ was 5.24 ± 0.36 vol %, and for P group, it was 4.07 ± 0.47 vol %. For H group, f was 14.3 ± 3.74 br./min; and for P group, it was 17.9 ± 4.50 br./min. For H group, $CVR_{CO_2 }$ was 8.91 ± 2.16%; and for P group, it was 12.7 ± 3.14%. The comprehensive parameter, which includes all three characteristics of the breathing pattern, such as a decrease in FetCO₂, an increase in f, and disorders of the breathing rhythm, appeared to be the most informative indicator of psychogenic dyspnea. It was shown that capnography with automatic processing of the breathing pattern is an objective method for studying the mechanisms of psychogenic dyspnea.