931 research outputs found
The effects of cognitive styles on naive impetus theory application degrees of pre-service science teachers
Cataloged from PDF version of article.The purpose of this study was to determine whether there is a relationship
between pre-service science teachers’ Field Dependent or Field Independent (FD/FI) cognitive
styles and the application of degrees of naive impetus theory. The sample consisted of 122 preservice
science teachers (97 females and 25 males) who were enrolled in the Introductory
Physics course required by the Science Education program. Data were collected in two
successive years, after the completion of the required Introductory Physics undergraduate
courses, in 2008 and 2009. The Group Embedded Figure Test and Impetus Theory
Application Test (a two-tier-type test) were administered to assess the FD/FI tendency of
students and to determine the degree students applied the naïve impetus theory, respectively.
Initial results showed that a majority of students had made use of the native impetus theory
repeatedly. The results also indicated that the degree to which students applied the naïve
impetus theory was statistically related to their FD/FI cognitive styles. The findings of this
research showed that there existed a statistically significant difference between the FI and FD
students’ degree of applying the naïve impetus theory in favor of FI students. However, the test
score gap between FI and FD students remained almost constant regardless of the testing
instruments utilized in this study
YIELD AND ITS COMPONENTS IN FIELD PEA (Pisum arvense L.) LINES
Morphological characters such as main stem length (cm), number of branches per plant, leaf length (cm), number of leaves per main stem, number of leaflets per leaf, diameter of main stem (mm), pods / main stem and seeds / pod as well as agricultural herbage yield (t ha-1), dry matter yield (t ha-1), seed yield (t ha-1), crude
protein (%) were investigated in Trakya, during the 1999-2002. The maximum main stem length (124.375 cm), leaf length (24.808 cm), number of pods per main stem (16.526), herbage yield (27.881 t ha-1), dry matter yield (7.319 t ha-1) and seed yield (2.590 t ha-1) were determined from the 16-K and 16-DY field pea lines. K line has given higher values than four lines for the number of branches per plant (5.567). Main stem diameter ranged from 3.077 to 4.300 mm. It’s found that the 23.025 leaves/main stem, 6.833 leaflets/leaf, 7.692 seeds/pod and 17.550% crude protein from the field pea lines
Quantum phases in mixtures of fermionic atoms
A mixture of spin-polarized light and heavy fermionic atoms on a finite size
2D optical lattice is considered at various temperatures and values of the
coupling between the two atomic species. In the case, where the heavy atoms are
immobile in comparison to the light atoms, this system can be seen as a
correlated binary alloy related to the Falicov-Kimball model. The heavy atoms
represent a scattering environment for the light atoms. The distributions of
the binary alloy are discussed in terms of strong- and weak-coupling
expansions. We further present numerical results for the intermediate
interaction regime and for the density of states of the light particles. The
numerical approach is based on a combination of a Monte-Carlo simulation and an
exact diagonalization method. We find that the scattering by the correlated
heavy atoms can open a gap in the spectrum of the light atoms, either for
strong interaction or small temperatures.Comment: 15 pages, 8 figure
Near-field light localization using subwavelength apertures incorporated with metamaterials
Cataloged from PDF version of article.We report strong near-field electromagnetic localization by using subwavelength apertures and metamaterials that operate at microwave frequencies. We designed split ring resonators with distinct configurations in order to obtain extraordinary transmission results. Furthermore, we analyzed the field localization and focusing characteristics of the transmitted evanescent waves. The employed metamaterial configurations yielded an improvement on the transmission efficiency on the order of 27 dB and 50 dB for the deep subwavelength apertures. The metamaterial loaded apertures are considered as a total system that offered spot size conversion ratios as high as 7.12 and 9.11 for the corresponding metamaterial configurations. The proposed system is shown to intensify the electric fields of the source located in the near-field. It also narrows down the electromagnetic waves such that a full width at half maximum value of λ/29 is obtained. © 2012 Elsevier B.V. All rights reserved
Yield and its components in fi eld pea (Pisum arvense L.) lines.
ABSTRACT Morphological characters such as main stem length (cm), number of branches per plant, leaf length (cm), number of leaves per main stem, number of leaflets per leaf, diameter of main stem (mm), pods / main stem and seeds / pod as well as agricultural herbage yield (t ha -1 ), dry matter yield (t ha -1 ), seed yield (t ha -1 ), crude protein (%) were investigated in Trakya, during the 1999-2002. The maximum main stem length (124.375 cm), leaf length (24.808 cm), number of pods per main stem (16.526), herbage yield (27.881 t ha -1 ), dry matter yield (7.319 t ha -1 ) and seed yield (2.590 t ha -1 ) were determined from the 16-K and 16-DY field pea lines. K line has given higher values than four lines for the number of branches per plant (5.567). Main stem diameter ranged from 3.077 to 4.300 mm. It's found that the 23.025 leaves/main stem, 6.833 leaflets/leaf, 7.692 seeds/pod and 17.550% crude protein from the field pea lines
Experimental demonstration of the enhanced transmission through circular and rectangular sub-wavelength apertures using omega-like split-ring resonators
Cataloged from PDF version of article.Enhanced transmission through circular and rectangular sub-wavelength apertures using omega-shaped split-ring resonator is
numerically and experimentally demonstrated at microwave frequencies. We report a more than 150,000-fold enhancement through
a deep sub-wavelength aperture drilled in a metallic screen. To the authors’ best knowledge, this is the highest experimentally
obtained enhancement factor reported in the literature. In the paper, we address also the origins and the physical reasons behind the
enhancement results. Moreover, we report on the differences occurring when using circular, rectangular apertures as well as doublesided
and single-sided omega-like split ring resonator structures.
(C) 2012 Elsevier B.V. All rights reserve
First record of the red shrimp, Aristeus antennatus (Risso, 1816) (Decapoda: Aristeidae) from the Aegean Sea coast of Turkey
A female specimen of the deep-water red shrimp, Aristeus antennatus(Risso, 1816) was caught at depths of between 550 m and 670 m during 2005 by trawling off the Marmaris coast. A. antennatus is a species known to inhabit only the Levantine Sea coast of Turkey. This paper is on the first record of the species along the southern Aegean Sea coast of Turke
Sustainable development of smallholder crop-livestock farming in developing countries
Meeting the growing demand for animal-sourced food, prompted by population growth and increases in average per-capita income in low-income countries, is a major challenge. Yet, it also presents significant potential for agricultural growth, economic development, and reduction of poverty in rural areas. The main constraints to livestock producers taking advantage of growing markets include; lack of forage and feed gaps, communal land tenure, limited access to land and water resources, weak institutions, poor infrastructure and environmental degradation. To improve rural livelihood and food security in smallholder crop-livestock farming systems, concurrent work is required to address issues regarding efficiency of production, risk within systems and development of whole value chain systems. This paper provides a review of several forage basedstudies in tropical and non-tropical dry areas of the developing countries. A central tenet of this paper is that forages have an essential role in agricultural productivity, environmental sustainability and livestock nutrition in smallholder mixed farming systems
Transmission enhancement through deep subwavelength apertures using connected split ring resonators
Cataloged from PDF version of article.We report astonishingly high transmission enhancement factors through a subwavelength aperture at microwave frequencies by placing connected split ring resonators in the vicinity of the aperture. We carried out numerical simulations that are consistent with our experimental conclusions. We experimentally show higher than 70,000-fold extraordinary transmission through a deep subwavelength aperture with an electrical size of lambda/31x lambda/12 (width x length), in terms of the operational wavelength. We discuss the physical origins of the phenomenon. Our numerical results predict that even more improvements of the enhancement factors are attainable. Theoretically, the approach opens up the possibility for achieving very large enhancement factors by overcoming the physical limitations and thereby minimizes the dependence on the aperture geometries. (C) 2010 Optical Society of Americ
Analytical Model of Connected Bi-Omega: Robust Particle for the Selective Power Transmission Through Sub-Wavelength Apertures
Cataloged from PDF version of article.In this paper, we present a new analytical model of
the connected bi-omega structure consisting of two bi-omega particles
connected together through their arms. A single bi-omega
particle consists of a pair of regular equal omegas with mirror
symmetry. Assuming the individual bi-omega particle electrically
small, the equivalent circuit is derived, in order to predict its
resonant frequency. Then, two bi-omega particles are connected
together, obtaining a symmetric structure that supports two
fundamental modes, with even and odd symmetries, respectively.
The proposed analytical model, then, is used to develop a procedure
allowing the design of the particle for a desired resonant
frequency. The effectiveness of the proposed analytical model and
design guidelines is confirmed by proper comparisons to full-wave
numerical and experimental results. We also demonstrate through
a proper set of experiments that the resonant frequencies of the
connected bi-omega particle depend only on the geometrical and
electrical parameters of the omegas and are rather insensitive to
the practical scenario where the particle itself is actually used, e.g.
in free-space, rectangular waveguide or across an aperture in a
metallic screen
- …