52,639 research outputs found
Motivational Strategies Used by an Englsh Teacher at Hand Fortuna Center
This is a qualitative study on the use of motivational strategies by the English teacher at Hand Fortuna Center. This study was based on Dörnyei\u27s (2001) theory about motivational strategies and focused on the interaction between the teacher and his students in the classroom. The data were collected by using video recording and interview. The observation was done in three meetings within two weeks. The duration of the class was 90 minutes for each meeting. The findings showed that the teacher used five out of eight motivational strategies in the classroom. There were making learning stimulating and enjoyable, protecting the learners\u27 self-esteem and increase their self-confidence, presenting task in a motivating way, allowing learners to maintain a positive social image, and promoting cooperation among the learners. For the interview, the writer found that the reason why the teacher used the motivational strategies. It was because the strategies could increase students\u27 motivation in learning language
Application of Dressing Method for Long Wave-Short Wave Resonance Interaction Equation
In this paper we investigate the application of Zakharov - Shabat dressing
method to (2+1) - dimensional long wave - short wave resonance interaction
equation (LSRI). Using this method we can construct the exact N - soliton
solution of this equation depending on arbitrary constants. It contains both
solutions which don't decay along N different directions in space infinity, and
"dromion" ones, or localized solutions that decay exponentially in all
directions.Comment: 8 page
Multi-Behavioral Endpoint Testing Of An 87-Chemical Compound Library In Freshwater Planarians
There is an increased recognition in the field of toxicology of the value of medium-to-high-throughput screening methods using in vitro and alternative animal models. We have previously introduced the asexual freshwater planarian Dugesia japonica as a new alternative animal model and proposed that it is particularly well-suited for the study of developmental neurotoxicology. In this paper, we discuss how we have expanded and automated our screening methodology to allow for fast screening of multiple behavioral endpoints, developmental toxicity, and mortality. Using an 87-compound library provided by the National Toxicology Program (NTP), consisting of known and suspected neurotoxicants, including drugs, flame retardants, industrial chemicals, polycyclic aromatic hydrocarbons (PAHs), pesticides and presumptive negative controls, we further evaluate the benefits and limitations of the system for medium-throughput screening, focusing on the technical aspects of the system. We show that, in the context of this library, planarians are the most sensitive to pesticides with 16/16 compounds causing toxicity and the least sensitive to PAHs, with only 5/17 causing toxicity. Furthermore, while none of the presumptive negative controls were bioactive in adult planarians, 2/5, acetaminophen and acetylsalicylic acid, were bioactive in regenerating worms. Notably, these compounds were previously reported as developmentally toxic in mammalian studies. Through parallel screening of adults and developing animals, planarians are thus a useful model to detect such developmental-specific effects, which was observed for 13 chemicals in this library. We use the data and experience gained from this screen to propose guidelines for best practices when using planarians for toxicology screens
Telephone-cord instabilities in thin smectic capillaries
Telephone-cord patterns have been recently observed in smectic liquid crystal
capillaries. In this paper we analyse the effects that may induce them. As long
as the capillary keeps its linear shape, we show that a nonzero chiral
cholesteric pitch favors the SmA*-SmC* transition. However, neither the
cholesteric pitch nor the presence of an intrinsic bending stress are able to
give rise to a curved capillary shape.
The key ingredient for the telephone-cord instability is spontaneous
polarization. The free energy minimizer of a spontaneously polarized SmA* is
attained on a planar capillary, characterized by a nonzero curvature. More
interestingly, in the SmC* phase the combined effect of the molecular tilt and
the spontaneous polarization pushes towards a helicoidal capillary shape, with
nonzero curvature and torsion.Comment: Submitte
Primordial Gravitational Waves Enhancement
We reconsider the enhancement of primordial gravitational waves that arises
from a quantum gravitational model of inflation. A distinctive feature of this
model is that the end of inflation witnesses a brief phase during which the
Hubble parameter oscillates in sign, changing the usual Hubble friction to
anti-friction. An earlier analysis of this model was based on numerically
evolving the graviton mode functions after guessing their initial conditions
near the end of inflation. The current study is based on an equation which
directly evolves the normalized square of the magnitude. We are also able to
make a very reliable estimate for the initial condition using a rapidly
converging expansion for the sub-horizon regime. Results are obtained for the
energy density per logarithmic wave number as a fraction of the critical
density. These results exhibit how the enhanced signal depends upon the number
of oscillatory periods; they also show the resonant effects associated with
particular wave numbers.Comment: 25 pages, 14 figure
Approximating incompatible von Neumann measurements simultaneously
We study the problem of performing orthogonal qubit measurements
simultaneously. Since these measurements are incompatible, one has to accept
additional imprecision. An optimal joint measurement is the one with the least
possible imprecision. All earlier considerations of this problem have concerned
only joint measurability of observables, while in this work we also take into
account conditional state transformations (i.e., instruments). We characterize
the optimal joint instrument for two orthogonal von Neumann instruments as
being the Luders instrument of the optimal joint observable.Comment: 9 pages, 4 figures; v2 has a more extensive introduction + other
minor correction
Dipolar ground state of planar spins on triangular lattices
An infinite triangular lattice of classical dipolar spins is usually
considered to have a ferromagnetic ground state. We examine the validity of
this statement for finite lattices and in the limit of large lattices. We find
that the ground state of rectangular arrays is strongly dependent on size and
aspect ratio. Three results emerge that are significant for understanding the
ground state properties: i) formation of domain walls is energetically favored
for aspect ratios below a critical valu e; ii) the vortex state is always
energetically favored in the thermodynamic limit of an infinite number of
spins, but nevertheless such a configuration may not be observed even in very
large lattices if the aspect ratio is large; iii) finite range approximations
to actual dipole sums may not provide the correct ground sta te configuration
because the ferromagnetic state is linearly unstable and the domain wall energy
is negative for any finite range cutoff.Comment: Several short parts have been rewritten. Accepted for publication as
a Rapid Communication in Phys. Rev.
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