scholarly journals Inflection Points in Cubic Structures

Mathematics ◽  
2021 ◽  
Vol 9 (21) ◽  
pp. 2819
Author(s):  
Vladimir Volenec ◽  
Zdenka Kolar-Begović ◽  
Ružica Kolar-Šuper
Keyword(s):  
Inflection Point ◽  
Geometric Concepts ◽  
Inflection Points ◽  
Cubic Structure

In this paper, we introduce and study new geometric concepts in a general cubic structure. We define the concept of the inflection point in a general cubic structure and investigate relationships between inflection points and associated and corresponding points in a general cubic structure.

scholarly journals Resistance behaviour of carbon fibre-reinforced polymers subjected to lightning strikes: Experimental investigation and application

2019 ◽  
Vol 28 ◽  
pp. 2633366X1989227 ◽  
Author(s):  
Jian Chen ◽  
Zhengcai Fu ◽  
Yang Zhao
Keyword(s):  
Carbon Fibre ◽  
Surface Resistance ◽  
Inflection Point ◽  
Front Surface ◽  
Resistance Change ◽  
Reinforced Polymers ◽  
Change Rate ◽  
Lightning Strikes ◽  
Inflection Points ◽  
Carbon Fibre Reinforced Polymers

It is difficult to monitor lightning damage to carbon fibre-reinforced polymers (CFRPs) online. This work experimentally investigates the changes associated with the electrical resistance of CFRPs subjected to lightning strikes. Two kinds of simulated lightning currents with different amplitudes in the range of 10–80 kA were injected into the CFRP samples. By measuring and comparing the changes in the struck-side (front) surface resistance, the surface resistance of the side opposite to the struck-side (back) and the oblique resistance of each sample before and after the lightning strike, it was observed that inflection points exist in the curve of the resistance change rate. The resistance decreases with increasing peak currents before the inflection point and increases when the peak current goes beyond the inflection point. The change rate of the front surface resistance is more sensitive to the lightning damage than are those of the back surface resistance and the oblique resistance. Different simulated lightning currents have approximately the same action integrals at the inflection points of resistance change rate. The characteristics indicate that resistance change detection could be a possible method for the online monitoring of CFRP lightning damage.

scholarly journals A GROWTH STUDY OF BEEF CATTLE

1981 ◽  
Vol 61 (4) ◽  
pp. 1041-1048 ◽  
Author(s):  
L. A. GOONEWARDENE ◽  
R. T. BERG ◽  
R. T. HARDIN
Keyword(s):  
Birth Weight ◽  
Beef Cattle ◽  
Inflection Point ◽  
Prediction Errors ◽  
Von Bertalanffy ◽  
University Of Alberta ◽  
Inflection Points ◽  
Richards Function ◽  
Residual Variances ◽  
The University

Four growth equations (Richards, Brody, Von Bertalanffy and Logistic) were fitted to data from two breed groups of female beef cattle, purebred Hereford (HE) and synthetic of Charolais, Angus and Galloway (SY), which were maintained at the University of Alberta beef breeding research ranch at Kinsella, Alberta. All functions fitted three common parameters (an asymptote, an integration constant and a maturing rate parameter). Two functions (Von Bertalanffy and Logistic) had fixed inflection points while the Richards function fitted the inflection point as a fourth parameter. The Brody function had no inflection point. Based on the R2, mean prediction errors (MPE) and residual variances, the Richards function, with a variable inflection point, provided the best overall and the most consistent fit to both sets of data, followed by the Brody function with no inflection point. The Richards was the only function that could predict birth weight with any degree of accuracy. The Logistic and Von Bertalanffy functions, with fixed inflection points, provided poor estimates of actual weights at each end of the growth curve, overestimating birth weight and converging too early leading to underestimation of adult weight or the asymptote. Intermediate weights were reasonably well estimated by these functions. The HE group showed a 28% greater maturing rate compared with the SY based on the Richards function.

scholarly journals A Proper Increasing in the Testosterone Level May Be Associated With Better Pregnancy Outcomes for Patients With Tubal or Male Infertility During in vitro Fertilization/Intracytoplasmic Sperm Injection

2021 ◽  
Vol 12 ◽  
Author(s):  
Zhiyan Chen ◽  
Duoduo Zhang ◽  
Zhengyi Sun ◽  
Qi Yu
Keyword(s):  
Male Infertility ◽  
Pregnancy Outcomes ◽  
Inflection Point ◽  
Upward Trend ◽  
Time Points ◽  
Inflection Points ◽  
Group 3 ◽  
The Relationship ◽  
Group 1

We aimed to investigate the relationship between testosterone (T) levels and pregnancy outcomes in patients with tubal or male infertility at different times during in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) cycles. Patients with tubal or male infertility and normal androgen levels undergoing IVF/ICSI were consecutively recruited. We performed a longitudinal analysis of T levels at three time points (i.e., T0: baseline, T1: trigger day, and T2: day after the trigger day) in three groups with different pregnancy outcomes (i.e., group 1: no pregnancy; group 2: clinical pregnancy but no live birth; and group 3: live birth) as repeated measurement data using linear mixed-effects models. We also plotted fitted curves depicting the relationship between T levels and a number of oocytes retrieved at different time points and identified the inflection points of the curves. In total, 3,012 patients were recruited. Groups 1 and 3 had improvements in T levels at the three time points. After refitting, the slope in group 3 was significantly higher than that in group 1 (P = 0.000). Curves that reflected the association between T levels and numbers of retrieved oocytes presented an upward trend before a certain inflection point, after which the curves had no obvious changes or fell with increasing T levels. The inflection points for T0, T1, and T2 were calculated as 0.45, 0.94, and 1.09, respectively. A faster upward trend in T levels might be associated with better pregnancy outcomes. Within a range lower than a T level inflection point, more oocytes and embryos could be obtained with increasing T levels.

scholarly journals Using Probability Distribution Functions to Correlate Breakthrough Curves of Water and air Contaminants

2021 ◽  
Author(s):  
Khim Hoong Chu
Keyword(s):  
Breakthrough Curve ◽  
Inflection Point ◽  
Initial Period ◽  
Normal Function ◽  
Distribution Functions ◽  
Cumulative Distribution ◽  
Good Representation ◽  
Air Contaminants ◽  
Inflection Points ◽  
Log Normal

Abstract This paper reports the use of five probability cumulative distribution functions (normal, log-normal, logistic, Gompertz, and Weibull) to correlate published breakthrough data of water and air contaminants (ciprofloxacin, ammonium, hydrogen chloride, and hydrogen sulfide). Because the shape of the ciprofloxacin breakthrough curve is fairly symmetric, it is well correlated by all five functions (R2 > 0.99). They also provide a good representation of the overall shape of the ammonium breakthrough curve (R2 > 0.99). However, none can describe the leakage of ammonium during the initial period of column operation. The log-normal and Weibull functions give an excellent representation of the tailing HCl data while the normal, logistic, and Gompertz functions are quite poor. This difference in performance can be explained by the different characteristics of their inflection points. The log-normal and Weibull functions have a floating inflection point, which gives them flexibility in tracing the shape of the tailing data. The invariant inflection points of the normal, logistic, and Gompertz curves restrict their data fitting ability. Only the log-normal function can provide a reasonable fit to the H2S data with strong tailing. It is shown that the invariant inflection point of a probability function can be converted to a floating one. A version of the Gompertz function so modified provides a good quantitative correlation of the tailing data of H2S (R2 = 0.99).

Inflection points of cardiovascular responses and oxygenation are correlated in the distal but not the proximal portions of muscle during incremental exercise

2004 ◽  
Vol 97 (3) ◽  
pp. 867-873 ◽  
Author(s):  
Masaki Mizuno ◽  
Ken Tokizawa ◽  
Takashi Iwakawa ◽  
Isao Muraoka
Keyword(s):  
Inflection Point ◽  
Vastus Lateralis ◽  
Linear Regression Analysis ◽  
Cardiovascular Responses ◽  
Distal Portion ◽  
Incremental Exercise ◽  
Proximal Portion ◽  
Regression Equations ◽  
Muscle Deoxygenation ◽  
Inflection Points

To test whether there is a regional difference in the exercise pressor reflex within a given muscle, we investigated the relationship between the inflection points of cardiovascular responses and muscle oxygenation during exercise. Seven subjects performed incremental exercise, which consisted of incremental 30-s static knee extensions, each separated by 30 s of recovery. The workload started at 5% maximal voluntary contraction (MVC) and increased by 5% MVC for each increment until exhaustion. Changes (Δ) in the concentrations (denoted by brackets) of oxygenated Hb (O2Hb) and deoxygenated Hb (HHb) were monitored in proximal and distal portions of the vastus lateralis by near-infrared spectroscopy. The inflection points of mean arterial pressure (MAP), calf vascular resistance (CVR), and muscle deoxygenation index (Δ[O2Hb − HHb]) were calculated as the intersection point of two regression equations obtained at lower and higher workloads. The inflection point of Δ[O2Hb − HHb] differed significantly between proximal and distal portions (28.5 ± 3.0 vs. 39.5 ± 3.0%MVC, P < 0.05). Linear regression analysis showed significant correlations between the inflection point of Δ[O2Hb − HHb] in the distal portion and MAP ( r = 0.89; P < 0.01) and CVR ( r = 0.89; P < 0.05), but no significant relationship between the inflection point in the proximal portion and MAP or CVR. These data show that the inflection point of muscle deoxygenation differs between proximal and distal portions within the vastus lateralis during incremental exercise and suggest that the distal portion of the vastus lateralis contributes more to the pressor response than does the proximal portion.

scholarly journals Spatiotemporal inflection points in human running: Effects of training level and athletic modality

PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0258709
Author(s):  
Yuta Goto ◽  
Tetsuya Ogawa ◽  
Gaku Kakehata ◽  
Naoya Sazuka ◽  
Atsushi Okubo ◽  
...  
Keyword(s):  
Inflection Point ◽  
Random Order ◽  
Step Length ◽  
Training Level ◽  
Segmented Regression ◽  
Specific Training ◽  
Distance Runners ◽  
Inflection Points ◽  
The Relationship ◽  
Human Running

The effect of the different training regimes and histories on the spatiotemporal characteristics of human running was evaluated in four groups of subjects who had different histories of engagement in running-specific training; sprinters, distance runners, active athletes, and sedentary individuals. Subjects ran at a variety of velocities, ranging from slowest to fastest, over 30 trials in a random order. Group averages of maximal running velocities, ranked from fastest to slowest, were: sprinters, distance runners, active athletes, and sedentary individuals. The velocity-cadence-step length (V-C-S) relationship, made by plotting step length against cadence at each velocity tested, was analyzed with the segmented regression method, utilizing two regression lines. In all subject groups, there was a critical velocity, defined as the inflection point, in the relationship. In the velocity ranges below and above the inflection point (slower and faster velocity ranges), velocity was modulated primarily by altering step length and by altering cadence, respectively. This pattern was commonly observed in all four groups, not only in sprinters and distance runners, as has already been reported, but also in active athletes and sedentary individuals. This pattern may reflect an energy saving strategy. When the data from all groups were combined, there were significant correlations between maximal running velocity and both running velocity and step length at the inflection point. In spite of the wide variety of athletic experience of the subjects, as well as their maximum running velocities, the inflection point appeared at a similar cadence (3.0 ± 0.2 steps/s) and at a similar relative velocity (65–70%Vmax). These results imply that the influence of running-specific training on the inflection point is minimal.

scholarly journals Inflection points and industry change: Was Andy Grove right after all?

2016 ◽  
Vol 7 (1) ◽  
pp. 7-26
Author(s):  
Fred Phillips ◽  
G. George Hwang ◽  
Pornpimol Limprayoon
Keyword(s):  
Life Cycle ◽  
Inflection Point ◽  
Coping Mechanisms ◽  
Tipping Point ◽  
Organizational Sustainability ◽  
Inflection Points ◽  
Product Technology ◽  
Technology Life Cycle ◽  
And Control

We examine whether the ‘strategic inflection points’ described by former Intel CEO Andy Grove correspond to mathematical inflection points in the product/technology life cycle. We find one sense in which they do and two senses in which they do not. This leads to a mapping of colloquial uses of inflection point, tipping point, volatility, chaos, and turbulence against the scientific definitions of these terms. The mapping should be of use to researchers and educators, and also suggests to managers that the possibility of foresight and control in technology-dependent industries is more sharply limited than generally believed. The paper highlights implications for organizational sustainability and offers possible coping mechanisms for managers and directions for educators and researchers.

scholarly journals Tangentials in cubic structures

2020 ◽  
Vol 55 (2) ◽  
pp. 337-349
Author(s):  
Vladimir Volenec ◽  
◽  
Zdenka Kolar-Begović ◽  
Ružica Kolar-Šuper ◽  
◽  
...  
Keyword(s):  
Higher Order ◽  
Cubic Curve ◽  
New Concepts ◽  
Geometric Concepts ◽  
Cubic Structure

In this paper we study geometric concepts in a general cubic structure. The well-known relationships on the cubic curve motivate us to introduce new concepts into a general cubic structure. We will define the concept of the tangential of a point in a general cubic structure and we will study tangentials of higher-order. The characterization of this concept will be also given by means of the associated totally symmetric quasigroup. We will introduce the concept of associated and corresponding points in a cubic structure, and discuss the number of mutually different corresponding points. The properties of the introduced geometric concepts will be investigated in a general cubic structure.

scholarly journals Converging Newton’s Method With An Inflection Point of A Function

2017 ◽  
Vol 13 (2) ◽  
pp. 73
Author(s):  
Ridwan Pandiya ◽  
Ismail Bin Mohd
Keyword(s):  
Iterative Method ◽  
Newton’S Method ◽  
Newton's Method ◽  
Inflection Point ◽  
Initial Point ◽  
One Dimensional ◽  
Root Finding ◽  
Inflection Points ◽  
Starting Point ◽  
The Relationship

For long periods of time, mathematics researchers struggled in obtaining the appropriate starting point when implementing root finding methods, and one of the most famous and applicable is Newton’s method. This iterative method produces sequence that converges to a desired solution with the assumption that the starting point is close enough to a solution. The word “close enough” indicates that we actually do not have any idea how close the initial point needed so that this point can bring into a convergent iteration. This paper comes to answer that question through analyzing the relationship between inflection points of one-dimensional non-linear function with the convergence of Newton’s method. Our purpose is to illustrate that the neighborhood of an inflection point of a function never fails to bring the Newton’s method convergent to a desired solution

Comparison of the lower inflection point on the static total respiratory compliance curve with outcomes in postoperative cardiothoracic patients

2001 ◽  
Vol 10 (6) ◽  
pp. 399-407 ◽  
Author(s):  
M Boyle ◽  
P Way ◽  
M Pinfold ◽  
J Lawrence
Keyword(s):  
Inflection Point ◽  
Prospective Observational Study ◽  
Recruitment Strategy ◽  
Low Flow ◽  
Positive End Expiratory Pressure ◽  
Lower Inflection Point ◽  
Respiratory Compliance ◽  
Inflection Points ◽  
Compliance Curve ◽  
The Mean

BACKGROUND: Routine use of positive end-expiratory pressure (based on the pressure at the lower inflection point on the static total respiratory compliance curve) along with a maneuver to recruit atelectatic lung has been advocated after cardiothoracic surgery. OBJECTIVES: To determine if the lower inflection point is related to outcomes in patients after sternotomy and cardiopulmonary bypass. METHOD: A prospective observational study involving estimation of the lower inflection point on the inflation pressure-volume plot obtained with a low-flow technique. Duration of intubation, length of stay, respiratory complications, and results of spirometry were compared between patients with a "high " inflection point (&gt; or =10 cm H2O) and patients with a "low" inflection point (&lt; or =5 cm H2O). RESULTS: Ninety-five patients were enrolled. After exclusion for incomplete data, 65 patients (49 men, 16 women; mean age, 66.1 years; SD, 9.5 years) were included. The mean lower inflection point was 6.33 cm H2O (SD, 3.4 cm H2O). A second lower inflection point was observed on 5 plots (mean, 21 cm H2O; SD, 1.4 cm H2O). Nine patients had high inflection points (mean, 13.1 cm H2O; SD, 3.0 cm H2O), and 33 had low inflection points (mean, 3.9 cm H2O; SD, 0.98 cm H2O). No outcome measures differed between groups. CONCLUSIONS: In patients with short intubation times and predictable postoperative course, general use of a lung recruitment strategy involving sustained inflations and adjustment of positive end-expiratory pressure based on the lower inflection point is difficult to justify.

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