Abstract We show that in analytic sub-Riemannian manifolds of rank 2 satisfying a commutativity condition spiral-like curves are not length minimizing near the center spiral. The proof relies upon delicate construction competing curve.

Background: X-ray computed tomography (CT) examinations deliver a significant amount of radiation doses to patients comparing to conventional radiography examinations. The objective of the current study was to analyze and investigate the average patient received dose from axial and spiral CT exams in a medical imaging center. Material and Methods: In this study, the patient imaging tec...

Selection of spiral capillary tube for refrigeration appliances and the effect of changes in the parameters such as capillary tube dimensions i.e. capillary tube diameter, coil pitch, capillary tube length and inlet conditions of refrigerant to the capillary tube i.e. degree of subcooling, inlet pressure on the mass flow rate of the refrigerant, also investigation about the coiling effect of sp...

Trap building by animals is rare because it comes at a substantial cost. Using materials with properties that vary across environments maintains trap functionality. The sticky spiral silks of spider orb webs are used to catch flying prey. Web geometry, accompanied by compensatory changes in silk properties, may change across environments to sustain web functionality. We exposed the spider Cyclo...

OBJECTIVE To obtain reference values, to suggest optimal recording and stimulation site for radial motor nerve conduction study (RmNCS), and to analyze the correlation among RmNCS parameters, demographics and ultrasonography (US) findings. METHODS A total of 55 volunteers participated in this study. We hypothesized that 'lateral edge of spiral groove (A)' was the optimal stimulation site, and...

A single-arm rectangular spiral antenna is analyzed using the finite-difference time-domain method. The spiral is printed on a finite-size dielectric substrate backed by a finite-size conducting plane. Both the substrate and conducting planes are square with a side length of less than 0.6 0 ( 0: wavelength in free space). The radiation pattern is dependent on the outermost arm peripheral length...

This paper theoretically describes how to compose a single Pythagorean hodograph (PH) quintic Bézier spiral segment, between two circles with one circle inside the other. A spiral is free of local curvature extrema, making spiral design an interesting mathematical problem with importance for both physical and aesthetic applications. The curvature of a spiral varies monotonically with arc-length...

BACKGROUND Various special techniques for blind bedside transpyloric tube placement have been introduced into clinical practice. However, transpyloric spiral tube placement facilitated by a blind bedside method has not yet been reported. The objective of this prospective study was to evaluate the safety and efficiency of blind bedside postpyloric placement of a spiral tube as a rescue therapy s...

A 850 µm map of the interacting spiral galaxy M 51 shows well-defined spiral arms, closely resembling the structures seen in CO and HI emission. However, most of the 850 µm emission originates in an underlying exponential disk, a component that has not been observed before in a face-on galaxy at these wavelengths. The scale-length of this disk is 5.45 kpc, which is somewhat larger than the scal...