98,103 research outputs found
System for and method of freezing biological tissue
Biological tissue is frozen while a polyethylene bag placed in abutting relationship against opposed walls of a pair of heaters. The bag and tissue are cooled with refrigerating gas at a time programmed rate at least equal to the maximum cooling rate needed at any time during the freezing process. The temperature of the bag, and hence of the tissue, is compared with a time programmed desired value for the tissue temperature to derive an error indication. The heater is activated in response to the error indication so that the temperature of the tissue follows the desired value for the time programmed tissue temperature. The tissue is heated to compensate for excessive cooling of the tissue as a result of the cooling by the refrigerating gas. In response to the error signal, the heater is deactivated while the latent heat of fusion is being removed from the tissue while the tissue is changing phase from liquid to solid
Design of a blood-freezing system for leukemia research
Leukemia research involves the use of cryogenic freezing and storage equipment. In a program being carried out at the National Cancer Institute (NCI), bone marrow (white blood cells) was frozen using a standard cryogenic biological freezer. With this system, it is difficult to maintain the desired rate of freezing and repeatability from sample to sample. A freezing system was developed that satisfies the requirements for a repeatable, constant freezing rate. The system was delivered to NIC and is now operational. This report describes the design of the major subsystems, the analyses, the operating procedure, and final system test results
Magnetic ionization fronts II: Jump conditions for oblique magnetization
We present the jump conditions for ionization fronts with oblique magnetic
fields. The standard nomenclature of R- and D-type fronts can still be applied,
but in the case of oblique magnetization there are fronts of each type about
each of the fast- and slow-mode speeds. As an ionization front slows, it will
drive first a fast- and then a slow-mode shock into the surrounding medium.
Even for rather weak upstream magnetic fields, the effect of magnetization on
ionization front evolution can be important. [Includes numerical MHD models and
an application to observations of S106.]Comment: 9 pages, 10 figures, Latex, to be published in MNRA
Fabry-Perot Measurements of the Dynamics of Globular Cluster Cores: M15 (NGC~7078)
We report the first use of the Rutgers Imaging Fabry-Perot Spectrophotometer
to study the dynamics of the cores of globular clusters. We have obtained
velocities for cluster stars by tuning the Fabry-Perot to take a series of
narrow-band images at different wavelengths across one of the Na D (5890 AA)
absorption lines. Measuring the flux in every frame yields a short portion of
the spectrum for each star simultaneously. This proves to be a very efficient
method for obtaining accurate stellar velocities; in crowded regions we are
able to measure hundreds of velocities in 3-4 hours of observing time. We have
measured velocities with uncertainties of less than 5 km/s for 216 stars within
1.5' of the center of the globular cluster M15 (NGC 7078). The paper is a
uuencoded compressed postscript file
The time evaluation of resistance probability of a closed community against to occupation in a Sznajd like model with synchronous updating: A numerical study
In the present paper, we have briefly reviewed Sznajd's sociophysics model
and its variants, and also we have proposed a simple Sznajd like sociophysics
model based on Ising spin system in order to explain the time evaluation of
resistance probability of a closed community against to occupation. Using a
numerical method, we have shown that time evaluation of resistance probability
of community has a non-exponential character which decays as stretched
exponential independent the number of soldiers in one dimensional model.
Furthermore, it has been astonishingly found that our simple sociophysics model
is belong to the same universality class with random walk process on the
trapping space.Comment: 12 pages, 5 figures. Added a paragraph and 1 figure. To be published
in International Journal of Modern Physics
Explanation of the Tao effect
In a series of experiments Tao and coworkers\cite{tao1,tao2,tao3} found that
superconducting microparticles in the presence of a strong electrostatic field
aggregate into balls of macroscopic dimensions. No explanation of this
phenomenon exists within the conventional theory of superconductivity. We show
that this effect can be understood within an alternative electrodynamic
description of superconductors recently proposed that follows from an
unconventional theory of superconductivity. Experiments to test the theory are
discussed.Comment: Submitted to Science January 2nd, declined January 6th; to Nature
January 7th, declined January 13th; to PRL January 14th, declined February
25t
Domain walls inside localised orientifolds
The equations of motion of toroidal orientifold compactifications with fluxes
are in one-to-one correspondence with gauged supergravity if the orientifold
(and D-brane) sources are smeared over the compact space. This smeared limit is
identical to the approximation that ignores warping. It is therefore relevant
to compare quantities obtained from the gauged supergravity with the true 10d
solution with localised sources. In this paper we find the correspondence
between BPS domain walls in gauged SUGRA and 10D SUGRA with localised sources.
Our model is the simplest orientifold with fluxes we are aware of: an O6/D6
compactification on T^3/Z_2 in massive IIA with H_3-flux. The BPS domain walls
correspond to a O6/D6/NS5/D8 bound state. Our analysis reveals that the domain
wall energy computed in gauged SUGRA is unaffected by the localisation of the
O6/D6 sources.Comment: 26 pages, 1 figur
- …