1,413 research outputs found
An investigation of the increase in phonemic awareness in kindergarten students who were exposed to word sort activities
The purpose of this study was to determine if word sort activities would help improve the phonemic awareness of kindergarten students. The experimental and control groups consisted of students ranging in a variety of reading abilities. The experimental group received phonics instruction through the use of word sorting activities. The control group had no guidelines for phonics instruction. Any phonics lesson taught in the classroom were done according to the classroom instructors own plans and ideas. Pre-test and post-test scores showed that students that were exposed to word sort activities scored significantly higher on sound recognition tests then other students. Issues concerning phonics instruction in the classroom are discussed
The theory of the fluctuations in brightness of the Milky way. II.
In this paper the integral equation governing the fluctuations in brightness of the Milky Way is considered for the case in which the system extends to infinity in the direction of the line of sight. The equation is explicitly solved for the two cases in which all the clouds are equally transparent and when the frequency of occurrence of clouds with a transparency factor q is (n + 1)qn. The derived distributions of brightness are illustrated
Hydrogen tunneling in the perovskite ionic conductor BaCe(1-x)Y(x)O(3-d)
We present low-temperature anelastic and dielectric spectroscopy measurements
on the perovskite ionic conductor BaCe(1-x)Y(x)O(3-x/2) in the protonated,
deuterated and outgassed states. Three main relaxation processes are ascribed
to proton migration, reorientation about an Y dopant and tunneling around a
same O atom. An additional relaxation maximum appears only in the dielectric
spectrum around 60 K, and does not involve H motion, but may be of electronic
origin, e.g. small polaron hopping. The peak at the lowest temperature,
assigned to H tunneling, has been fitted with a relaxation rate presenting
crossovers from one-phonon transitions, nearly independent of temperature, to
two-phonon processes, varying as T^7, to Arrhenius-like. Substituting H with D
lowers the overall rate by 8 times. The corresponding peak in the dielectric
loss has an intensity nearly 40 times smaller than expected from the classical
reorientation of the electric dipole associated with the OH complex. This fact
is discussed in terms of coherent tunneling states of H in a cubic and
orthorhombically distorted lattice, possibly indicating that only H in the
symmetric regions of twin boundaries exhibit tunneling, and in terms of
reduction of the effective dipole due to lattice polarization.Comment: submitted to Phys. Rev.
The theory of the fluctuations in brightness of the Milky way. I.
In this paper the following statistical problem is considered. Let stars and interstellar clouds occur with a uniform distribution. Let the system extend to a linear distance L in the direction of a line of sight. Let a cloud reduce the intensity of the light of the stars immediately behind it by a factor q. Let the occurrence of clouds with a transparency factor q be governed by a frequency function ψ(q). Given all this,
- it is required to find the probability distribution, g(I, L), of the observed brightness, I. From a consideration of this problem it is shown that the following integral equation governs the distribution of brightness: g(u+ξ)+∂g/∂u+∂g/∂ξ=∫10g(u/q,ξ)ψ(q)dq/q, where u is the observed brightness measured in suitable units and ξ is the average number of clouds in the direction of the line of sight. It is further shown that the foregoing integral equation enables us to obtain explicit formulae for all the moments of g as functions of ξ and the moments of ψ(q). As an illustration of the use of these general formulae for the moments, an example investigated by Markarian has been reconsidered in an attempt to derive the mean and mean-square deviation of the optical thicknesses of the interstellar clouds
A new generalized domain decomposition strategy for the efficient parallel solution of the FDS-pressure equation. Part I: Theory, Concept and Implementation
Due to steadily increasing problem sizes and accuracy requirements as well as storage restrictions on single-processor systems, the efficient numerical simulation
of realistic fire scenarios can only be obtained on modern high-performance computers based on multi-processor architectures. The transition to those systems
requires the elaborate parallelization of the underlying numerical concepts which must guarantee the same result as a potentially corresponding serial execution and preserve the convergence order of the original serial method. Because
of its low degree of inherent parallelizm, especially the efficient parallelization of the elliptic pressure equation is still a big challenge in many simulation programs for fire-induced flows such as the Fire Dynamics Simulator (FDS). In order to avoid losses of accuracy or numerical instabilities, the parallelization process must definitely take into account the strong global character of the physical pressure. The current parallel FDS solver is based on a relatively coarse-grained parallellization concept which can’t guarantee these requirements in all cases.
Therefore, an alternative parallel pressure solver, ScaRC, is proposed which ensures a high degree of global coupling and a good computational performance at the same time. Part I explains the theory, concept and implementation of this
new strategy, whereas Part II describes a series of validation and verification tests to proof its correctness
Constraints on post-depositional isotope modifications in East Antarctic firn from analysing temporal changes of isotope profiles
The isotopic composition of water in ice sheets is extensively used to infer past climate changes. In low-accumulation regions their interpretation is, however, challenged by poorly constrained effects that may influence the initial isotope signal during and after deposition of the snow. This is reflected in snow-pit isotope data from Kohnen Station, Antarctica, which exhibit a seasonal cycle but also strong interannual variations that contradict local temperature observations. These inconsistencies persist even after averaging many profiles and are thus not explained by local stratigraphic noise. Previous studies have suggested that post-depositional processes may significantly influence the isotopic composition of East Antarctic firn. Here, we investigate the importance of post-depositional processes within the open-porous firn (≳ 10 cm depth) at Kohnen Station by separating spatial from temporal variability. To this end, we analyse 22 isotope profiles obtained from two snow trenches and examine the temporal isotope modifications by comparing the new data with published trench data extracted 2 years earlier. The initial isotope profiles undergo changes over time due to downward advection, firn diffusion and densification in magnitudes consistent with independent estimates. Beyond that, we find further modifications of the original isotope record to be unlikely or small in magnitude (≪ 1 ‰ RMSD). These results show that the discrepancy between local temperatures and isotopes most likely originates from spatially coherent processes prior to or during deposition, such as precipitation intermittency or systematic isotope modifications acting on drifting or loose surface snow
What are Hybrid Development Methods Made Of?
Regardless of company size or industry sector, a majority of project teams and companies use customized processes that combine different development methods-so-called hybrid development methods. Even though such hybrid development methods are highly individualized, a common understanding of how to systematically construct synergetic practices is missing. Based on 1,467 data points from a large-scale online survey among practitioners, we study the current state of practice in process use to answer the question: What are hybrid development methods made of? Our findings reveal that only eight methods and few practices build the core of modern software development. This small set allows for statistically constructing hybrid development methods
Comparison of acute non-visual bright light responses in patients with optic nerve disease, glaucoma and healthy controls.
This study examined the effect of optic nerve disease, hence retinal ganglion cell loss, on non-visual functions related to melanopsin signalling. Test subjects were patients with bilateral visual loss and optic atrophy from either hereditary optic neuropathy (n = 11) or glaucoma (n = 11). We measured melatonin suppression, subjective sleepiness and cognitive functions in response to bright light exposure in the evening. We also quantified the post-illumination pupil response to a blue light stimulus. All results were compared to age-matched controls (n = 22). Both groups of patients showed similar melatonin suppression when compared to their controls. Greater melatonin suppression was intra-individually correlated to larger post-illumination pupil response in patients and controls. Only the glaucoma patients demonstrated a relative attenuation of their pupil response. In addition, they were sleepier with slower reaction times during nocturnal light exposure. In conclusion, glaucomatous, but not hereditary, optic neuropathy is associated with reduced acute light effects. At mild to moderate stages of disease, this is detected only in the pupil function and not in responses conveyed via the retinohypothalamic tract such as melatonin suppression
What are Hybrid Development Methods Made Of? An Evidence-Based Characterization
Among the multitude of software development processes available, hardly any is used by the book. Regardless of company size or industry sector, a majority of project teams and companies use customized processes that combine different development methods— so-called hybrid development methods. Even though such hybrid development methods are highly individualized, a common understanding of how to systematically construct synergetic practices is missing. In this paper, we make a first step towards devising such guidelines. Grounded in 1,467 data points from a large-scale online survey among practitioners, we study the current state of practice in process use to answer the question: What are hybrid development methods made of? Our findings reveal that only eight methods and few practices build the core of modern software development. This small set allows for statistically constructing hybrid development methods. Using an 85% agreement level in the participants’ selections, we provide two examples illustrating how hybrid development methods are characterized by the practices they are made of. Our evidence-based analysis approach lays the foundation for devising hybrid development methods
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