Teachers’ Attitudes toward Problem Texts in Literature Classes

Contemporary youth literature is characterised by deviation from the traditional pattern of obedient child and a happy childhood. The topics on which the writers in Slovenia in the seventies and especially in the nineties openly wrote, have become problem or taboo – so denoted by certain groups, especially those of teachers and parents. The article presents the views of Slovenian primary school teachers and teachers of Slovenian towards discussing problem texts in literature classes in basic school. On the basis of empirical non-experimental research, which included 33 teachers of Slovenian and 58 primary school teachers, statistically significant difference in defining the suitability of topics, and in relation to problem texts have been found

A Lattice-Boltzmann model for suspensions of self-propelling colloidal particles

We present a Lattice-Boltzmann method for simulating self-propelling (active) colloidal particles in two-dimensions. Active particles with symmetric and asymmetric force distribution on its surface are considered. The velocity field generated by a single active particle, changing its orientation randomly, and the different time scales involved are characterized in detail. The steady state speed distribution in the fluid, resulting from the activity, is shown to deviate considerably from the equilibrium distribution.Comment: 8 pages, 13 figure

The hydrology of northern boreal lakes in the Taiga Shield and Plains, Northwest Territories and the importance of catchment characteristics in mediating responses to climate

Freshwater lakes are prominent features across northern boreal regions and are sensitive to changing climate conditions. This study, spanning the 2017-18 ice-free seasons, broadens our understanding of how variable climate and landscape conditions influence subarctic lake hydrology in the North Slave Region near Yellowknife, Northwest Territories (NT), Canada. We studied 20 lakes located within the Taiga Shield and Taiga Plains ecozones through an integrated approach, utilizing water isotope tracers (δ2H and δ18O), lake level changes, local meteorological conditions and remotely sensed catchment data. Lake water isotope data were obtained twice during the ice-free season (May and August) and evaporation/inflow (E/I) ratios were calculated to identify the relative importance of catchment hydrological controls. Hydrological data were compared to measured and modelled catchment characteristics, including relative lake/catchment size, slope, land cover and recent wildfire burn area. Overall, precipitation was a major driver of seasonal and interannual lake hydrological change, while evaporation was a major driver of summer water loss. Relative catchment size (lake area to catchment area (LA/CA)) was found to be an important driver of lake hydrology, however, this relationship is complicated by storage deficits associated with variable meteorological conditions. During wet conditions (e.g., freshet and periods of high rainfall), lakes with larger catchments (low LA/CA) had more positive water balances than lakes with high LA/CA. Under drier conditions, lake catchment size and associated fill-and-spill hydrological connectivity was reduced. Lake basins with high LA/CA (particularly those with shallower depth and greater surface area) were more prone to evaporative water loss. Lake hydrological conditions were less influenced by catchment land cover compositions, including burn area. Findings presented here highlight important drivers of lake water balances in subarctic boreal regions, which are sensitive to ongoing changes in climate. This study is part of a broader research project funded and supported by NWT Cumulative Impact Monitoring Program (CIMP), which is using a multi-proxy, paleo-ecological approach to determine long-term (i.e., 2,000 years) records of hydrology, drought, fire and water quality to inform future policy planning

How the geometry makes the criticality in two - component spreading phenomena?

We study numerically a two-component A-B spreading model (SMK model) for concave and convex radial growth of 2d-geometries. The seed is chosen to be an occupied circle line, and growth spreads inside the circle (concave geometry) or outside the circle (convex geometry). On the basis of generalised diffusion-annihilation equation for domain evolution, we derive the mean field relations describing quite well the results of numerical investigations. We conclude that the intrinsic universality of the SMK does not depend on the geometry and the dependence of criticality versus the curvature observed in numerical experiments is only an apparent effect. We discuss the dependence of the apparent critical exponent $\chi_{a}$ upon the spreading geometry and initial conditions.Comment: Uses iopart.cls, 11 pages with 8 postscript figures embedde

Aspherical gravitational monopoles

We show how to construct non-spherically-symmetric extended bodies of uniform density behaving exactly as pointlike masses. These ``gravitational monopoles'' have the following equivalent properties: (i) they generate, outside them, a spherically-symmetric gravitational potential $M/|x - x_O|$; (ii) their interaction energy with an external gravitational potential $U(x)$ is $- M U(x_O)$; and (iii) all their multipole moments (of order $l \geq 1$) with respect to their center of mass $O$ vanish identically. The method applies for any number of space dimensions. The free parameters entering the construction are: (1) an arbitrary surface $\Sigma$ bounding a connected open subset $\Omega$ of $R^3$; (2) the arbitrary choice of the center of mass $O$ within $\Omega$; and (3) the total volume of the body. An extension of the method allows one to construct homogeneous bodies which are gravitationally equivalent (in the sense of having exactly the same multipole moments) to any given body.Comment: 55 pages, Latex , submitted to Nucl.Phys.

Early stages of ramified growth in quasi-two-dimensional electrochemical deposition

I have measured the early stages of the growth of branched metal aggregates formed by electrochemical deposition in very thin layers. The growth rate of spatial Fourier modes is described qualitatively by the results of a linear stability analysis [D.P. Barkey, R.H. Muller, and C.W. Tobias, J. Electrochem. Soc. {\bf 136}, 2207 (1989)]. The maximum growth rate is proportional to $(I/c)^\delta$ where $I$ is the current through the electrochemical cell, $c$ the electrolyte concentration, and $\delta = 1.37 \pm 0.08$. Differences between my results and the theoretical predictions suggest that electroconvection in the electrolyte has a large influence on the instability leading to ramified growth.Comment: REVTeX, four ps figure

Exact results for nucleation-and-growth in one dimension

We study statistical properties of the Kolmogorov-Avrami-Johnson-Mehl nucleation-and-growth model in one dimension. We obtain exact results for the gap density as well as the island distribution. When all nucleation events occur simultaneously, the island distribution has discontinuous derivatives on the rays x_n(t)=nt, n=1,2,3... We introduce an accelerated growth mechanism where the velocity increases linearly with the island size. We solve for the inter-island gap density and show that the system reaches complete coverage in a finite time and that the near-critical behavior of the system is robust, i.e., it is insensitive to details such as the nucleation mechanism.Comment: 9 pages, revtex, also available from http://arnold.uchicago.edu/~ebn

Structure formation in active networks

Structure formation and constant reorganization of the actin cytoskeleton are key requirements for the function of living cells. Here we show that a minimal reconstituted system consisting of actin filaments, crosslinking molecules and molecular-motor filaments exhibits a generic mechanism of structure formation, characterized by a broad distribution of cluster sizes. We demonstrate that the growth of the structures depends on the intricate balance between crosslinker-induced stabilization and simultaneous destabilization by molecular motors, a mechanism analogous to nucleation and growth in passive systems. We also show that the intricate interplay between force generation, coarsening and connectivity is responsible for the highly dynamic process of structure formation in this heterogeneous active gel, and that these competing mechanisms result in anomalous transport, reminiscent of intracellular dynamics

Eulerian and Lagrangian properties of biophyscial intermittency in the ocean

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