Search results for "perimeter"
showing 10 items of 46 documents
Walking Speed as an Alternative Measure of Functional Status in Patients with Lumbar Spinal Stenosis
2019
Objective The main objective was to compare estimated walking perimeter (WP) and actual WP during a free walking test (6-minute walk test [6MWT]) in patients with lumbar spinal stenosis (LSS). The second objective was to describe the correlation between measured gait parameters and functional parameters. Methods This was a single-center prospective study including 38 patients with symptomatic LSS (23 men, 15 women; mean age, 69.3 ± 7.9 years). The intervention was the 6MWT. For the main outcome measure, patients were first asked to verbally estimate their WP. Then, WP was evaluated using a 6MWT at a self-selected speed. In the absence of need to stop, and if a distance of 500 m was not reac…
Flow resistance law under suspended sediment laden conditions
2020
Abstract The uniform flow resistance equation, in the form due to Manning or Darcy-Weisbach, is widely applied to establish the stage-discharge relationship of a river cross-section. The application of this equation, namely the slope-area method, allows to indirectly measure the corresponding river discharge by measurements of bed slope, water level, cross-section area, wetted perimeter and an estimate of channel roughness. In this paper, a recently deduced flow resistance equation for open channel flow was tested during conditions of suspended sediment-laden flow. First, the flow resistance equation was determined by dimensional analysis and by applying the condition of incomplete self-sim…
Short time existence of the classical solution to the fractional mean curvature flow
2019
Abstract We establish short-time existence of the smooth solution to the fractional mean curvature flow when the initial set is bounded and C 1 , 1 -regular. We provide the same result also for the volume preserving fractional mean curvature flow.
Rigidity and sharp stability estimates for hypersurfaces with constant and almost-constant nonlocal mean curvature
2018
We prove that the boundary of a (not necessarily connected) bounded smooth set with constant nonlocal mean curvature is a sphere. More generally, and in contrast with what happens in the classical case, we show that the Lipschitz constant of the nonlocal mean curvature of such a boundary controls its $C^2$-distance from a single sphere. The corresponding stability inequality is obtained with a sharp decay rate.
Rectifiability of the reduced boundary for sets of finite perimeter over RCD(K,N) spaces
2019
This paper is devoted to the study of sets of finite perimeter in RCD(K,N) metric measure spaces. Its aim is to complete the picture of the generalization of De Giorgi’s theorem within this framework. Starting from the results of Ambrosio et al. (2019) we obtain uniqueness of tangents and rectifiability for the reduced boundary of sets of finite perimeter. As an intermediate tool, of independent interest, we develop a Gauss–Green integration-by-parts formula tailored to this setting. These results are new and non-trivial even in the setting of Ricci limits. peerReviewed
Morphological characterization of ejaculated cynomolgus monkey (Macaca fascicularis) sperm
1999
The aim of this study was to give reference values for the frequency of morphological sperm abnormalities present in the semen from non-experimental cynomolgus monkeys as well as for the dimensions of sperm heads. Spermatozoa from the liquid portion of electroejaculates from 14 cynomolgus monkeys were air-dried as smears, fixed, and stained with Harris's Haematoxylin and subjected to visual analysis of morphology and computer-aided analysis of ten morphometric variables. The majority (83%) of sperm were morphologically normal. Tail defects were the most common (11%), and showed the highest variation between individuals, the values ranging between 4 and 23%. Head abnormalities consisted of l…
Estudio crítico de los índices de severidad y la superficie afectada por el incendio de Sierra de Luna (Zaragoza)
2017
[EN] To determine the area burned by fire and its associated severity related to this forest fire taken place in Sierra de Luna (Zaragoza), on July 4th, 2015, three spectral indices derived from Landsat-8 imagery have been calculated: NDVI, NBR and BAI. Comparing the results obtained from each of them, in a wildland fire with extensive crop areas surrounded by forested areas, it has been demonstrated that combination of ΔNBR and BAI substantially improves the calculation of the burned area, concerning both in its external perimeter and in the unburned zones inside of the perimeter. For severity calculation is proposed a new methodology based on before and after NBR differences and its BAI c…
3D-2D dimensional reduction for a nonlinear optimal design problem with perimeter penalization
2012
A 3D-2D dimension reduction for a nonlinear optimal design problem with a perimeter penalization is performed in the realm of $\Gamma$-convergence, providing an integral representation for the limit functional.
Dido's problem in the plane for domains with fixed diameter
1994
We find the connected compact domains in the closed half-plane, with fixed area and diameter, which minimize the relative perimeter.
Nonlocal Isoperimetric Inequality
2019
For the nonlocal perimeter, there is also an isoperimetric inequality, and here the main hypothesis used on J is that it is radially nonincreasing.