14,562 research outputs found
Rotary antenna attenuator
Radio frequency attenuator, having negligible insertion loss at minimum attenuation, can be used for making precise antenna gain measurements. It is small in size compared to a rotary-vane attenuator
Producing graphite with desired properties
Isotropic or anisotropic graphite is synthesized with precise control of particle size, distribution, and shape. The isotropic graphites are nearly perfectly isotropic, with thermal expansion coefficients two or three times those of ordinary graphites. The anisotropic graphites approach the anisotropy of pyrolytic graphite
Breast feeding practices and views among diabetic women: a retrospective cohort study
Objective:
to explore the pattern and experiences of breast-feeding practices among diabetic women.
Design:
retrospective cohort study using maternal records and postal questionnaires in a Baby-Friendly hospital.
Participants:
diabetic mothers including women with gestational diabetes, and type 1 and 2 diabetes mellitus.
Findings:
from the total group of respondents, 81.9% intended to breast feed. The actual breast feeding rates were 81.9% at birth, 68.1% at 2 weeks and 28.7% at 6 months postpartum. Major themes that were identified from women's experiences included information and advice, support vs. pressure, classification and labelling, and expectations.
Conclusions:
more than two-thirds of the diabetic women intended to breast feed and actually did breast feed in this study. For both the total study population and the type 1 and 2 diabetics alone, more than half were still breast feeding at 2 weeks postpartum, and approximately one-third were still breast feeding at 6 months postpartum.
Implications for practice:
structured support, provided for women through Baby-Friendly initiatives, was appreciated by the diabetic women in this study. The extent to which this support influenced the highly successful breast feeding practices in this group of women needs focused investigation. The need for a delicate balancing act between pressure and advice in order to prevent coercion was noted.</p
The z=0.8596 Damped Lyman Alpha Absorbing Galaxy Toward PKS 0454+039
We present {\it Hubble Space Telescope} and ground--based data on the
metal line absorption system along the line of sight to PKS
0454+0356. The system is a moderate redshift damped Lyman alpha system, with
~cm as measured from the {\it
Faint Object Spectrograph} spectrum. We also present ground--based images which
we use to identify the galaxy which most probably gives rise to the damped
system; the most likely candidate is relatively underluminous by QSO absorber
standards ( for and \kms Mpc), and
lies kpc in projection from the QSO sightline. Ground--based
measurements of Zn~II, Cr~II, and Fe~II absorption lines from this system allow
us to infer abundances of [Zn/H]=, [Cr/H]=, and [Fe/H]=,
indicating overall metallicity similar to damped systems at , and that
the depletion of Cr and Fe onto dust grains may be even {\it less} important
than in many of the high redshift systems of comparable metallicity. Limits
previously placed on the 21-cm optical depth in the system, together
with our new N(H~I) measurement, suggest a very high spin temperature for the
H~I, K.Comment: changed uuencode header to produce .Z file so that unix uncompress
command will work without modifying file nam
Structure of Micro-instabilities in Tokamak Plasmas: Stiff Transport or Plasma Eruptions?
Solutions to a model 2D eigenmode equation describing micro-instabilities in
tokamak plasmas are presented that demonstrate a sensitivity of the mode
structure and stability to plasma profiles. In narrow regions of parameter
space, with special plasma profiles, a maximally unstable mode is found that
balloons on the outboard side of the tokamak. This corresponds to the
conventional picture of a ballooning mode. However, for most profiles this mode
cannot exist and instead a more stable mode is found that balloons closer to
the top or bottom of the plasma. Good quantitative agreement with a 1D
ballooning analysis is found provided the constraints associated with higher
order profile effects, often neglected, are taken into account. A sudden
transition from this general mode to the more unstable ballooning mode can
occur for a critical flow shear, providing a candidate model for why some
experiments observe small plasma eruptions (Edge Localised Modes, or ELMs) in
place of large Type I ELMs.Comment: 11 pages, 3 figure
Rectenna system design
The function of the rectenna in the solar power satellite system is described and the basic design choices based on the desired microwave field concentration and ground clearance requirements are given. One important area of concern, from the EMI point of view, harmonic reradiation and scattering from the rectenna is also designed. An optimization of a rectenna system design to minimize costs was performed. The rectenna cost breakdown for a 56 w installation is given as an example
Transition state theory and the dynamics of hard disks
The dynamics of two and five disk systems confined in a square has been
studied using molecular dynamics simulations and compared with the predictions
of transition state theory. We determine the partition functions Z and
Z^\ddagger of transition state theory using a procedure first used by Salsburg
and Wood for the pressure. Our simulations show this procedure and transition
state theory are in excellent agreement with the simulations. A generalization
of the transition state theory to the case of a large number of disks N is made
and shown to be in full agreement with simulations of disks moving in a narrow
channel. The same procedure for hard spheres in three dimensions leads to the
Vogel-Fulcher-Tammann formula for their alpha relaxation time.Comment: 1 new author, new simulations and figures, less speculation. Now 6
pages, 6 figures, 1 animation. Animation may be viewed at
http://www.theory.physics.manchester.ac.uk/~godfrey/supplement/activated_dynamics2.htm
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