15,493 research outputs found
Between-word junctures in early multi-word speech
Most children aged 1;6 to 2;0 begin to use utterances of two words or more. It is therefore important for child phonologists to consider the development of phonetic and phonological phenomena that characterize connected speech. The longitudinal case study reported here investigated three juncture types – assimilation, elision and liaison – in the speech of a typically-developing child between the ages of 2;4 and 3;4.
Attempts at production of these adult juncture types occurred from the onset of two-word utterances. However, for some juncture types, the child still had to perfect the intergestural relationships and gestural articulations that the adult between-word junctures demand. This process of phonetic development was largely accomplished by the age of 3;4. With one exception, between-word junctures appear not to be the result of learned phonological rules or processes. The exception is liaison involving /r/, which did not occur until the child was three years old
Geometric phases for corotating elliptical vortex patches
We describe a geometric phase that arises when two elliptical vortex patches corotate. Using the Hamiltonian moment model of Melander, Zabusky, and Styczek [J. Fluid Mech. 167, 95–115 (1986)] we consider two corotating uniform elliptical patches evolving according to the second order truncated equations of the model. The phase is computed in the adiabatic setting of a slowly varying Hamiltonian as in the work of Hannay [J. Phys. A 18, 221–230 (1985)] and Berry [Proc. R. Soc. London, Ser. A 392, 45–57 (1984)]. We also discuss the geometry of the symplectic phase space of the model in the context of nonadiabatic phases. The adiabatic phase appears in the orientation angle of each patch—it is similiar in form and is calculated using a multiscale perturbation procedure as in the point vortex configuration of Newton [Physica D 79, 416–423 (1994)] and Shashikanth and Newton [J. Nonlinear Sci. 8, 183–214 (1998)], however, an extra factor due to the internal stucture of the patch is present. The final result depends on the initial orientation of the patches unlike the phases in the works of Hannay and Berry [J. Phys. A 18, 221–230 (1985)]; [Proc. R. Soc. London, Ser. A 392, 45–57 (1984)]. We then show that the adiabatic phase can be interpreted as the holonomy of a connection on the trivial principal fiber bundle pi:T2×S1-->S1, where T2 is identified with the product of the momentum level sets of two Kirchhoff vortex patches and S1 is diffeomorphic to the momentum level set of two point vortex motion. This two point vortex motion is the motion that the patch centroids approach in the adiabatic limit
Electron paramagnetic resonance and photochromism of in diamond
The defect in diamond formed by a vacancy surrounded by three
nearest-neighbor nitrogen atoms and one carbon atom,
, is found in of natural diamonds.
Despite being the earliest electron paramagnetic
resonance spectrum observed in diamond, to date no satisfactory simulation of
the spectrum for an arbitrary magnetic field direction has been produced due to
its complexity. In this work, is identified in
-doped synthetic diamond following irradiation and annealing.
The spin Hamiltonian parameters are revised
and used to refine the parameters for ,
enabling the latter to be accurately simulated and fitted for an arbitrary
magnetic field direction. Study of under
excitation with green light indicates charge transfer between
and . It is argued that this charge
transfer is facilitated by direct ionization of ,
an as-yet unobserved charge state of
Development and evaluation of scatterometer data processing algorithms
There are no author-identified significant results in this report
Migration in the Tenth District : long-term trends and current developments
The movement of people into and out of a state can have important implications for the state’s economy. The total net inflow of people to a state matters because it affects the overall supply of workers in the state. Economists predict that growth in the national labor force will slow in coming decades as a result of such factors as the aging of the baby boomers and the decline in the fertility rate. As this happens, the availability of workers is likely to become an increasingly more important factor in the location decisions of firms. ; Migration matters not only for the size of a state’s workforce but also for the composition of the workforce. The spread of computers and advances in information technology have increased the demand for highly educated workers over the last two decades. Most economists expect the demand for such workers to continue growing in response to further advances in technology. But there will also continue to be a need for unskilled workers to perform jobs at the bottom of the job distribution. In deciding where to locate, firms are likely to pay careful attention to the educational composition of a state’s workforce in addition to the size. The most important determinant of the educational composition of the workforce is the quality of the state’s educational institutions. But also important is whether the state is retaining and attracting the kinds of workers in demand by businesses—for example, whether the state is suffering a net gain or net loss of college graduates to the rest of the nation, and whether the state is receiving too large or too small an influx of less educated immigrants from abroad. ; Focusing on the last half century, Keeton and Newton examine overall patterns in total migration and migration by level of education in Tenth District states. They show that the net inflow of people from other states has been consistently positive in only one state, Colorado, but has gradually improved in most other states. In addition, immigration increased greatly in most district states but ended up more important than in the nation only in Colorado. They also show that many district states have experienced both a net loss of college graduates to the rest of the nation and a net gain of people without high school degrees from abroad. The effects of these migration flows on the mix of workers have been greatly outweighed up till now by increases in education in the population at large. Finally, the authors show that in the current decade migration flows have taken a turn for the worse in several states, but this shift was due to temporary changes in relative economic conditions.Federal Reserve District, 10th
Surveying the solar system by measuring angles and times: from the solar density to the gravitational constant
A surprisingly large amount of information on our solar system can be gained
from simple measurements of the apparent angular diameters of the sun and the
moon. This information includes the average density of the sun, the distance
between earth and moon, the radius of the moon, and the gravitational constant.
In this note it is described how these and other quantities can be obtained by
simple earthbound measurements of angles and times only, without using any
explicit information on distances between celestial bodies. The pedagogical and
historical aspects of these results are also discussed briefly.Comment: 12 pges, one figur
The effects of dehydration on the aerobic and anaerobic capacities of men, part IV FINAL scientific report
Dehydration effects on work capacity and aerobic capacities of me
Part III - The effects of thermal stresses on the aerobic and anaerobic work capacities of men Final scientific report
Effects of hyperthermia and hypothermia on aerobic and anaerobic work capacities of me
Zipf Law for Brazilian Cities
This work studies the Zipf Law for cities in Brazil. Data from censuses of
1970, 1980, 1991 and 2000 were used to select a sample containing only cities
with 30,000 inhabitants or more. The results show that the population
distribution in Brazilian cities does follow a power law similar to the ones
found in other countries. Estimates of the power law exponent were found to be
2.22 +/- 0.34 for the 1970 and 1980 censuses, and 2.26 +/- 0.11 for censuses of
1991 and 2000. More accurate results were obtained with the maximum likelihood
estimator, showing an exponent equal to 2.41 for 1970 and 2.36 for the other
three years.Comment: 12 pages, 6 figures, 3 tables, Elsevier LaTeX, accepted for
publication in "Physica A". Correction of minor mistyping (eq. 8
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