Comparison of the Second-derivative Critical-point Method with Fourier Analysis for Noise Removal

2014 ◽  
Vol 64 (10) ◽  
pp. 963-967
Author(s):  
Han Gyeol PARK ◽  
Tae Jung KIM* ◽  
Jun Seok BYUN ◽  
Yu Ri KANG ◽  
Young Dong KIM†
Keyword(s):  
Fourier Analysis ◽  
Critical Point ◽  
Noise Removal ◽  
Point Method ◽  
Second Derivative

Scanning Electron Microscopy of Dried and Acid Treated Shells of Difflugia

1973 ◽  
Vol 31 ◽  
pp. 448-449
Author(s):  
Barry S. Eckert ◽  
S. M. McGee-Russell
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Critical Point ◽  
Point Method ◽  
External Structure ◽  
Cell Locomotion ◽  
Single Opening ◽  
Scanning Electron

Difflugia lobostoma is a shelled amoeba. The shell is an external structure of considerable mass which presents the animal with special restrictions in cell locomotion which are met by the development of active pseudopodial lobopodia containing, apparently, an organized system of thick and thin microfilaments (Eckert and McGee-Russell, 1972). The shell is constructed of sand grains picked up from the environment, and cemented into place with a secretion. There is a single opening through which lobopods extend. The organization of the shell was studied by scanning electron microscopy (SEM).Intact shells or animals with shells were dried by the critical point method of Anderson (1966) or air dried, after primary fixation in glutaraldehyde.

Local minimizers of the Willmore functional

Analysis ◽  
2015 ◽  
Vol 35 (2) ◽  
Author(s):  
Florian Skorzinski
Keyword(s):  
Critical Point ◽  
Local Minimizer ◽  
Positive Definite ◽  
Second Derivative ◽  
Sufficient Condition ◽  
Conformal Transformations ◽  
Willmore Functional ◽  
Local Minimizers

AbstractSince the Willmore functional is invariant with respect to conformal transformations and reparametrizations, the kernel of the second derivative of the functional at a critical point will always contain a subspace generated by these transformations. We prove that the second derivative being positive definite outside this space is a sufficient condition for a critical point to be a local minimizer.

Ejection fraction by combined inverse Fourier analysis and second-derivative technique: Correlation with isocontour method

1986 ◽  
Vol 12 (2) ◽  
pp. 69-71
Author(s):  
Suppiah Balachandran ◽  
Stuart Eason ◽  
Lynn McGuire ◽  
Suzanne Bernard ◽  
Charles Boyd
Keyword(s):  
Ejection Fraction ◽  
Fourier Analysis ◽  
Second Derivative

A multiaxial criterion for notch high-cycle fatigue using a critical-point method

2008 ◽  
Vol 75 (7) ◽  
pp. 1864-1874 ◽  
Author(s):  
Andrea Carpinteri ◽  
Andrea Spagnoli ◽  
Sabrina Vantadori ◽  
Danilo Viappiani
Keyword(s):  
Critical Point ◽  
High Cycle Fatigue ◽  
Point Method ◽  
Cycle Fatigue

scholarly journals THE STRANDEDNESS OF MEIOTIC CHROMOSOMES FROM ONCOPELTUS

1966 ◽  
Vol 31 (1) ◽  
pp. 31-42 ◽  
Author(s):  
Stephen L. Wolfe ◽  
Godfrey M. Hewitt
Keyword(s):  
Electron Microscope ◽  
Critical Point ◽  
Living Cells ◽  
Point Method ◽  
Oncopeltus Fasciatus ◽  
Langmuir Trough ◽  
Ringer’S Solution ◽  
Meiotic Chromosomes ◽  
Parallel Folding

Meiotic chromosomes were isolated from male Oncopeltus fasciatus by dissecting the testes under insect Ringer's solution and spreading the living cells on the Langmuir trough. After being dried by the critical point method, preparations were examined under the electron microscope. Chromosomes at all stages of prophase prove to be multistranded. A significant increase in the number of parallel 250 A fibers in the chromosomes occurs between zygotene and diakinesis. Parallel folding, rather than true multistrandedness, is interpreted as the mechanism responsible for this observed increase in multistrandedness. It has not been possible to determine whether the multistrandedness observed at leptotene represents true multistrandedness or is the result of parallel folding. Apparent multistrandedness is lost at metaphase when the 250 A fibers of the chromosomes become coiled more tightly. In preparations isolated by these methods, no structures other than the 250 A chromosome fibers are visible in the chromomeres, which appear as regionally coiled or folded areas of the fibers along the arm of the chromosome.

A more conclusive and more inclusive second derivative test

2020 ◽  
Vol 104 (560) ◽  
pp. 247-254
Author(s):  
Ronald Skurnick ◽  
Christopher Roethel
Keyword(s):  
Critical Point ◽  
Critical Points ◽  
Local Minimum ◽  
Local Maximum ◽  
Number Line ◽  
Second Derivative ◽  
First Derivative ◽  
Line Test ◽  
First Derivative Test ◽  
Derivative Test

Given a differentiable function f with argument x, its critical points are those values of x, if any, in its domain for which either f′ (x) = 0 or f′ (x) is undefined. The first derivative test is a number line test that tells us, definitively, whether a given critical point, x = c, of f(x) is a local maximum, a local minimum, or neither. The second derivative test is not a number line test, but can also be applied to classify the critical points of f(x). Unfortunately, the second derivative test is, under certain conditions, inconclusive.

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