4,062 research outputs found
On the Statistical Distribution of Epidermal Papillomata in Mice
IN a previous investigation reported from this laboratory (Ball and McCarter, 1960) it was noted that tumours produced in the skin of the CFW mouse by treatment with 7,12-dimethylbenz(a)anthracene (DMBA) and croton oil, were not distributed among the mice in accordance with the expected Poisson's distribution. Animals bearing no tumours and those bearing many were much more numerous than expected. A quantitative analysis of induced primary adenomatous pulmonary tumours in mice was reported by Polissar and Shimkin (1954). They showed that the occurrence of such tumours was subject to Poisson's distribution and that deviations from this distribution could be attributed to heterogeneity of susceptibility in the animals. We have now analyzed the data obtained in our laboratory in three populations of mice undergoing epidermal carcinogenesis. MATERIALS AND METHODS Strain CFW.-These mice were females, purchased from Carworth Farms Inc., New City, New York. They were housed in groups of 10 in acrylic plastic boxes with stainless steel tops. The bedding was sawdust. Water and Purina Fox Chow Cubes were freely available. Strain CFW/D.-This strain originated when, through error, a male was included among the female CFW mice purchased from the supplier in 1958. Since that time, brother-sister mating has been carried out with a view to obtaining a single inbred line. Litters selected for brother-sister mating were chosen on the basis of health, number in the litter and even distribution of the sexes and not for sensitivity to carcinogenesis. The mice were in the thirteenth and fourteenth inbred generations when used. They were cared for as described above. Strain I.-This strain was obtained several years ago through the kindness of Dr. H. B. Andervont. The mice had been mated brother-to-sister for 71 to 72 generations when the experiment was begun. Chemicals. 7,1 2-dimethylbenz(a)anthracene and benzo((a)pyrene were obtained from Eastman Organic Chemicals. Croton oil was obtained from Bush and Co., Canada. Paraffin oil viscosity 125/135 NF was a product of Fisher Scientific Co., Montreal, Canada. Meprobamate (Miltown) was kindly supplied by Dr. F. M
Efficient Coil Design by Electromagnetic Topology Optimization for Electromagnetic Sharp Edge Forming of DP980 Steel Sheet
This paper proposes a design method of the tool coil by topology optimization for the
electromagnetic sharp edge forming process. Topology optimization is an approach that
optimizes material configuration in a given domain to meet the design requirements. The
design problem for the tool coil is defined as enhancing efficiency of the forming process
and optimization problem is set to be maximization of the Lorentz force induced on the tool
coil. A new topology optimization formulation based on the numerical methods for
electromagnetism using FEM and BEM is developed for maximization of the Lorentz force.
Optimum design of the tool coil is obtained by the topology optimization using the element
density approach. The optimized result is compared with other coils which have different
configurations to show the effectiveness of the proposed method. The idea of applying
topology optimization to the design of the tool coil is successful and this formulation deals
effectively for the optimization problems
Electronic density of states derived from thermodynamic critical field curves for underdoped La-Sr-Cu-O
Thermodynamic critical field curves have been measured for
over the full range of carrier concentrations
where superconductivity occurs in order to determine changes in the normal
state density of states with carrier concentration. There is a substantial
window in the plane where the measurements are possible because the
samples are both thermodynamically reversible and the temperature is low enough
that vortex fluctuations are not important. In this window, the data fit
Hao-Clem rather well, so this model is used to determine and
for each temperature and carrier concentration. Using N(0) and the ratio of the
energy gap to transition temperature, , as fitting
parameters, the curves give over the
whole range of . Values of N(0) remain rather constant in the optimum-doped
and overdoped regime, but drops quickly toward zero in the underdoped regime.
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Dosimetric comparison study between intensity modulated radiation therapy and three-dimensional conformal proton therapy for pelvic bone marrow sparing in the treatment of cervical cancer.
The objective was to compare intensity-modulated radiation therapy (IMRT) with 3D conformal proton therapy (3DCPT) in the treatment of cervical cancer. In particular, each technique's ability to spare pelvic bone marrow (PBM) was of primary interest in this study. A total of six cervical cancer patients (3 postoperative and 3 intact) were planned and analyzed. All plans had uniform 1.0 cm CTV-PTV margin and satisfied the 95% PTV with 100% isodose (prescription dose = 45 Gy) coverage. Dose-volume histograms (DVH) were analyzed for comparison. The overall PTV and PBM volumes were 1035.9 ± 192.2 cc and 1151.4 ± 198.3 cc, respectively. In terms of PTV dose conformity index (DCI) and dose homogeneity index (DHI), 3DCPT was slightly superior to IMRT with 1.00 ± 0.001, 1.01 ± 0.02, and 1.10 ± 0.02, 1.13 ± 0.01, respectively. In addition, 3DCPT demonstrated superiority in reducing lower doses (i.e., V30 or less) to PBM, small bowel and bladder. Particularly in PBM, average V10 and V20 reductions of 10.8% and 7.4% (p = 0.001 and 0.04), respectively, were observed. However, in the higher dose range, IMRT provided better sparing (> V30). For example, in small bowel and PBM, average reductions in V45 of 4.9% and 10.0% (p = 0.048 and 0.008), respectively, were observed. Due to its physical characteristics such as low entrance dose, spread-out Bragg peak and finite particle range of protons, 3DCPT illustrated superior target coverage uniformity and sparing of the lower doses in PBM and other organs. Further studies are, however, needed to fully exploit the benefits of protons for general use in cervical cancer
Vortex fluctuations in superconducting La-Sr-Cu-O
Vortex fluctuations in the system have been
studied as a function of magnetic field, temperature and carrier concentration
in order to determine the dimensionality of the fluctuations. For a
sample, there is a unique crossing-temperature on the magnetization vs.
temperature plots for all magnetic fields up to 7 T, and the data scale very
well with 2D fluctuation theory. At lower x-values where is much
smaller, there are two well defined crossing points, one at low fields
(typically less than 1 T) and another at high fields (typically 3-7 T). A fit
of the data to fluctuation theory shows that the low field crossing data scale
as 2D fluctuations and the high field crossing data scale as 3D fluctuations.
It would appear that as the magnetic field approaches , there is a 2D
to 3D cross-over where the low field 2D pancake vortex structure transforms
into a 3D vortex structure
Therapeutic embolization of the dural arteriovenous malformation involving the jugular bulb.
Pulsatile tinnitus is a rarely occurring symptom of vascular origin. Most frequently, the symptoms are due to an arteriovenous malformation, to a tumor of the jugular glomus or to a local arterial stenosis. A 39-yr-old Korean male suffering from pulsatile tinnitus of the left ear was diagnosed to have dural arteriovenous malformation of the jugular bulb. Magnetic resonance imaging and angiography revealed a high-velocity vascular lesion encroaching the internal jugular vein and sigmoid sinuses. Digital subtraction angiography demonstrated a dural arteriovenous malformation involving the jugular bulb. The arterial supply was from the neuromeningeal branch of the left ascending pharyngeal artery and inferior tympanic artery. Stenosis of the left jugular vein caused retrograde venous drainage through the contralateral transverse sinus. Superselective embolization of these feeding arteries was successfully performed using 25% mixture of N-butylcyanoacrylate and lipiodol. In postembolization period, his complaints of pulsatile tinnitus and buzzing noise behind his left ear disappeared
Classical generalized constant coupling model for geometrically frustrated antiferromagnets
A generalized constant coupling approximation for classical geometrically
frustrated antiferromagnets is presented. Starting from a frustrated unit we
introduce the interactions with the surrounding units in terms of an internal
effective field which is fixed by a self consistency condition. Results for the
magnetic susceptibility and specific heat are compared with Monte Carlo data
for the classical Heisenberg model for the pyrochlore and kagome lattices. The
predictions for the susceptibility are found to be essentially exact, and the
corresponding predictions for the specific heat are found to be in very good
agreement with the Monte Carlo results.Comment: 4 pages, 3 figures, 2 columns. Discussion about the zero T value of
the pyrochlore specific heat correcte
Evaluation of cognitive function in adult rhesus monkeys using the finger maze test
In research on cognitive function, the use of experimental animals is essential for the study of human cognitive processes and mechanisms. Furthermore, non-human primates are necessary for understanding higher cognitive functions in humans. However, there are few cognitive function tests available for non-human primates, Thus, we modified a finger maze test for application to non-human primates. In this study, we assessed learning and memory in 12 adult rhesus monkeys using a finger maze test that was developed to assess cognitive functions in captive non-human primates. The monkeys were trained with moving rewards indicating the correct direction, which allowed the monkeys to obtain the reward. Following training, subjects completed a learning trial and a memory trial two months later. Although the time required for training varied among the monkeys, 11 out of 12 monkeys completed the training and achieved a high success rate in the learning trial as well as in the memory trial conducted 2 months later. This is the first study to apply the finger maze test to adult rhesus monkeys. The finger maze test enabled us to assess learning and memory in several adult rhesus monkeys simultaneously
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