Niche Networks for New Entrants

1997 ◽  
Vol 1567 (1) ◽  
pp. 17-25 ◽  
Author(s):  
Christiaan Hogendorn
Keyword(s):  
Shape Index ◽  
Shape Indices ◽  
Airline Networks ◽  
Different Shapes ◽  
Airline Network ◽  
New Entrants ◽  
Major Airlines ◽  
Returns To Scope

How new entrant carriers may use returns to airline networks in competition is discussed. In addition to overall returns to scope and density, there are more localized returns that are based on network shape. A network shape index, which is a measure of airline network concentration based on the Herfindahl-Hirschman index, is described. Airlines have chosen many different shapes as measured by the network shape index, and new entrants tend to be shaped differently from major airlines. A model of new entrant profitability relative to the major airlines is developed. New entrants whose network shape indices are substantially different from the major airlines have niche networks, and the model indicates that niche networks are associated with higher profitability.

scholarly journals Study on Structural Characteristics of China’s Passenger Airline Network Based on Network Motifs Analysis

2019 ◽  
Vol 11 (9) ◽  
pp. 2484 ◽  
Author(s):  
Ying Jin ◽  
Ye Wei ◽  
Chunliang Xiu ◽  
Wei Song ◽  
Kaixian Yang
Keyword(s):  
Airline Industry ◽  
Structural Characteristics ◽  
Building Blocks ◽  
Development Stage ◽  
Network Motifs ◽  
Characteristic Analysis ◽  
Airline Networks ◽  
Airline Network ◽  
Industry Sustainability ◽  
Advanced Development

The air passenger transport network system is an important agent of social and economic connections between cities. Studying on the airline network structure and providing optimization strategies can improve the airline industry sustainability evolution. As basic building blocks of broad networks, the concept of network motifs is cited in this paper to apply to the structural characteristic analysis of the passenger airline network. The ENUMERATE SUBGRAPHS (G, k) algorithm is used to identify the motifs and anti-motifs of the passenger airline network in China. A total of 37 airline companies are subjected to motif identification and exploring the structural and functional characteristics of the airline networks corresponding to different motifs. These 37 airline companies are classified according to the motif concentration curves into three development stages, which include mono-centric divergence companies at the low-level development stage, transitional companies at the intermediate development stage, and multi-centric and hierarchical companies at the advanced development stage. Finally, we found that adjusting the number of proper network motifs is useful to optimize the overall structure of airline networks, which is profitable for air transport sustainable development.

scholarly journals Model for the growth of the world airline network

2016 ◽  
Vol 27 (12) ◽  
pp. 1650141 ◽  
Author(s):  
T. Verma ◽  
N. A. M. Araújo ◽  
J. Nagler ◽  
J. S. Andrade ◽  
H. J. Herrmann
Keyword(s):  
Correlation Function ◽  
Growth Model ◽  
Physical Distance ◽  
Transport Networks ◽  
Model Network ◽  
The World ◽  
Airline Networks ◽  
Airline Network ◽  
The Difference

We propose a probabilistic growth model for transport networks which employs a balance between popularity of nodes and the physical distance between nodes. By comparing the degree of each node in the model network and the World Airline Network (WAN), we observe that the difference between the two is minimized for [Formula: see text]. Interestingly, this is the value obtained for the node–node correlation function in the WAN. This suggests that our model explains quite well the growth of airline networks.

scholarly journals Z-score of the log-transformed A Body Shape Index predicts low muscle mass in population with abdominal obesity: The U.S. and Korea National Health and Nutrition Examination Survey

PLoS ONE ◽  
2020 ◽  
Vol 15 (11) ◽  
pp. e0242557
Author(s):  
Shinje Moon ◽  
Yoon Jung Kim ◽  
Jae Myung Yu ◽  
Jun Goo Kang ◽  
Hye Soo Chung
Keyword(s):  
Muscle Mass ◽  
Abdominal Obesity ◽  
Body Shape ◽  
Shape Index ◽  
Nutrition Examination Survey ◽  
Z Score ◽  
Health And Nutrition ◽  
Shape Indices ◽  
A Body Shape Index ◽  
The U.S

Background and objective Sarcopenic obesity is associated with a higher risk of cardiometabolic disease and mortality than either sarcopenia or obesity alone. However, no study has investigated body shape indices for the assessment of sarcopenia in obese populations. Thus, this study aimed to evaluate the accuracy of body shape indices to assess sarcopenia in nationally representative populations with abdominal obesity. Methods Data from the U.S. National Health and Nutrition Examination Survey (U.S. NHANES) 1999–2006 and Korea NHANES (KNHANES) 2008–2011 were assessed. The association between Body Shape Index and sarcopenia was analyzed using a receiver operating characteristic curve. The Z-score of the log-transformed A Body Shape Index (LBSIZ) cut-off value was defined as that with the highest score of the Youden’s index. Changes in odds ratios (OR) for sarcopenia were investigated using restricted cubic spline (RCS) plots. Results This study included 8,013 American and 4,859 Korean adults with abdominal obesity. The overall area under the curve (AUC) of LBSIZ for sarcopenia was 0.816 (95% CI: 0.794–0.838) in U.S. NHANES and 0.822 (95% CI: 0.799–0.844) in KNHANES, which was higher than that of the body roundness index, conicity index, and waist to height ratio (p with DeLong’s test <0.001). The cut-off values for the LBSIZ were 1.05 (sensitivity, 88.0%; specificity, 81.5%) for American men, 0.45 (sensitivity, 77.1%; specificity, 70.6%) for American women, 1.15 (sensitivity, 77.5%; specificity, 77.1%) for Korean men and 0.95 (sensitivity, 74.3%; specificity, 69.3%) for Korean women in the development groups. Comparable results were verified in validation groups. The RCS plot indicated that ORs for sarcopenia rapidly increased with an increase in the LBSIZ cut-off value. Conclusion The increased LBSIZ could function as a reliable and cost-effective screening tool for assessing low muscle mass in populations with abdominal obesity.

scholarly journals Morphometric Identification, Gross and Histopathological Lesions of Eimeria Species in Japanese Quails (Coturnix coturnix japonica) in Zaria, Nigeria

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
H. A. Umar ◽  
I. A. Lawal ◽  
O. O. Okubanjo ◽  
A. M. Wakawa
Keyword(s):  
Developmental Stage ◽  
Developmental Stages ◽  
Eimeria Species ◽  
Shape Index ◽  
Molecular Techniques ◽  
Japanese Quails ◽  
Histopathological Lesions ◽  
Faecal Samples ◽  
Shape Indices ◽  
Haematoxylin And Eosin Stain

The objective of the study was to identify the species, gross and histopathological lesions of Eimeria in Japanese quails in Zaria. A total of 400 fresh faecal samples were collected and 10 quail birds were purchased from a quail farm. The faecal samples were processed using simple floatation technique. Oocysts shape indices of sporulated oocysts were determined. The intestines were observed for gross lesions and segments were analyzed using Giemsa stain and Haematoxylin and Eosin stain and then observed microscopically for the developmental stages of the parasite. Four species of Eimeria were identified in the study. Eimeria bateri of shape index of 1.36 conformed to the guidelines used while the other three Eimeria species with shape indices of 1.48, 1.03, and 1.40 were not confirmed. The main gross lesion seen was nonhaemorrhagic ballooning of the caeca. Intestinal scrapping smear revealed a developmental stage of the parasite (merozoites) in the jejunum. Histopathology also revealed a developmental stage (schizont) of the parasite in the caecum and desquamation of the epithelial lining with areas of necrosis. Further study is required using molecular techniques to properly identify the unknown species of Eimeria that were detected in the study.

Otolith shape index: is it a tool for trophic ecology studies?

2019 ◽  
Vol 99 (7) ◽  
pp. 1675-1682 ◽  
Author(s):  
Barbara Maichak de Carvalho ◽  
Henry Louis Spach ◽  
André Martins Vaz-Dos-Santos ◽  
Alejandra Vanina Volpedo
Keyword(s):  
Aspect Ratio ◽  
Trophic Ecology ◽  
Shape Index ◽  
Congeneric Species ◽  
Otolith Shape ◽  
Effective Separation ◽  
The Family ◽  
Shape Indices ◽  
Before And After

AbstractThe aim of this study was to test the effective separation of shape indices of otoliths of three species belonging to the family Sciaenidae before and after in vitro digestion. We measured 328 sagittal otoliths and applied six shape indices. Before the experiment, the aspect ratio (otolith height/otolith length%), circularity, ellipticity and relative surface of the sulcus acusticus were suitable for differentiating the species of genera Paralonchurus and Stellifer. Among the species of Stellifer, the aspect ratio and rectangularity were suitable. Otoliths exposed to in vitro digestion showed no significant differences in their morphometry before and after the experiment. After in vitro digestion, the aspect ratio and circularity were effective in separating Paralonchurus and Stellifer. However, none of the indices used in the present study were efficient to separate otoliths of congeneric species after in vitro digestion.

scholarly journals Combining Body Mass and Shape Indices in Clinical Practice

2016 ◽  
Vol 2016 ◽  
pp. 1-4 ◽  
Author(s):  
Jesse C. Krakauer ◽  
Nir Y. Krakauer
Keyword(s):  
Body Mass Index ◽  
Clinical Practice ◽  
Patient Care ◽  
Body Mass ◽  
Body Shape ◽  
Point Of Care ◽  
Shape Index ◽  
Relative Risks ◽  
Shape Indices ◽  
A Body Shape Index

We present preliminary clinical experience with combined consideration of the commonly used BMI (body mass index) and the newly developed ABSI (a body shape index) using a point of care anthropometric calculator for comparisons of index values and associated relative risks to population normals. In a series of 282 patients, BMI and ABSI were close to being independently distributed, supporting the value of considering both indices. Three selected cases illustrate scenarios where assessment of ABSI together with BMI could inform patient care and counseling. These data suggest that combined assessment of BMI and ABSI may prove useful in clinical practice.

scholarly journals Modeling airport congestion contagion by heterogeneous SIS epidemic spreading on airline networks

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0245043
Author(s):  
Alberto Ceria ◽  
Klemens Köstler ◽  
Rommy Gobardhan ◽  
Huijuan Wang
Keyword(s):  
Recovery Rate ◽  
Homogeneous Model ◽  
Stable State ◽  
Spreading Process ◽  
Sis Model ◽  
Heterogeneous Model ◽  
The Us ◽  
Airline Networks ◽  
Airline Network ◽  
Airport Congestion

In this work, we explore the possibility of using a heterogeneous Susceptible- Infected-Susceptible SIS spreading process on an airline network to model airport congestion contagion with the objective to reproduce airport vulnerability. We derive the vulnerability of each airport from the US Airport Network data as the congestion probability of each airport. In order to capture diverse flight features between airports, e.g. frequency and duration, we construct three types of airline networks. The infection rate of each link in the SIS spreading process is proportional to its corresponding weight in the underlying airline network constructed. The recovery rate of each node is also heterogeneous, dependent on its node strength in the underlying airline network, which is the total weight of the links incident to the node. Such heterogeneous recovery rate is motivated by the fact that large airports may recover fast from congestion due to their well-equipped infrastructures. The nodal infection probability in the meta-stable state is used as a prediction of the vulnerability of the corresponding airport. We illustrate that our model could reproduce the distribution of nodal vulnerability and rank the airports in vulnerability evidently better than the SIS model whose recovery rate is homogeneous. The vulnerability is the largest at airports whose strength in the airline network is neither too large nor too small. This phenomenon can be captured by our heterogeneous model, but not the homogeneous model where a node with a larger strength has a higher infection probability. This explains partially the out-performance of the heterogeneous model. This proposed congestion contagion model may shed lights on the development of strategies to identify vulnerable airports and to mitigate global congestion by e.g. congestion reduction at selected airports.

scholarly journals GWAS of allometric body-shape indices in UK Biobank identifies loci suggesting associations with morphogenesis, organogenesis, adrenal cell renewal and cancer

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sofia Christakoudi ◽  
Evangelos Evangelou ◽  
Elio Riboli ◽  
Konstantinos K. Tsilidis
Keyword(s):  
Body Shape ◽  
Genome Wide Association Study ◽  
Shape Index ◽  
Cell Renewal ◽  
Uk Biobank ◽  
Genetic Associations ◽  
Adrenal Cell ◽  
Shape Indices ◽  
Using Data ◽  
The Uk

AbstractGenetic studies have examined body-shape measures adjusted for body mass index (BMI), while allometric indices are additionally adjusted for height. We performed the first genome-wide association study of A Body Shape Index (ABSI), Hip Index (HI) and the new Waist-to-Hip Index and compared these with traditional indices, using data from the UK Biobank Resource for 219,872 women and 186,825 men with white British ancestry and Bayesian linear mixed-models (BOLT-LMM). One to two thirds of the loci identified for allometric body-shape indices were novel. Most prominent was rs72959041 variant in RSPO3 gene, expressed in visceral adipose tissue and regulating adrenal cell renewal. Highly ranked were genes related to morphogenesis and organogenesis, previously additionally linked to cancer development and progression. Genetic associations were fewer in men compared to women. Prominent region-specific associations showed variants in loci VEGFA and HMGA1 for ABSI and KLF14 for HI in women, and C5orf67 and HOXC4/5 for ABSI and RSPO3, VEGFA and SLC30A10 for HI in men. Although more variants were associated with waist and hip circumference adjusted for BMI compared to ABSI and HI, associations with height had previously been reported for many of the additional variants, illustrating the importance of adjusting correctly for height.

Hub-and-Spoke Airline Network Design Method and Application Based on Gravity Model

2012 ◽  
Vol 178-181 ◽  
pp. 1941-1946
Author(s):  
Lie Han ◽  
Ning Zhang
Keyword(s):  
Network Design ◽  
Gravity Model ◽  
Optimization Model ◽  
Design Method ◽  
Hub And Spoke ◽  
Airline Networks ◽  
Airline Network ◽  
Selection Of ◽  
Hub And Spoke Networks

Considering that lengthened transit airline route will reduce the quantity of customers in hub-and-spoke airline networks, the saved cost and reduced quantity of customers must be traded off when hub-and-spoke networks are designed. We apply gravity model to indicate the influence of quantity of customers due to different selection of hub airports. This paper presents a new network design method and mathematic optimization model whose object is to maximize total social net welfare. The hub-and-spoke network of Chinese fifteen cities is constructed using this method to demonstrate the effectiveness and practicability of this model.

Effects of Asperity Shape on the Adhesion Hysteresis Originated from Surface Roughness

2011 ◽  
Vol 213 ◽  
pp. 201-205
Author(s):  
Le Feng Wang ◽  
Bin Guo ◽  
Gui Ming Huang ◽  
Wei Bin Rong ◽  
Li Ning Sun
Keyword(s):  
Surface Roughness ◽  
Shape Index ◽  
Adhesive Contact ◽  
Solid Surfaces ◽  
Solid Contact ◽  
Dissipation Energy ◽  
Shape Indices ◽  
General Parameter ◽  
And Control ◽  
Different Levels

Adhesion of solid surfaces plays a significant role in many technical fields especially at micro and nano scale. The effect of asperity shape on the adhesion hysteresis originated from surface roughness has been investigated theoretically in this paper. Based on the adhesive contact model of single asperities with axisymmetric power-law shapes, the roughness-induced adhesion hysteresis is modeled by assuming the asperity heights follow a Gaussian distribution on the rough surface. The analysis results show that the dissipation energy decreases dramatically when the surface becomes rougher for all the shape indices, and the shape index affects the adhesion hysteresis at different levels with the variance of surface roughness. A general parameter consisting of the shape index of asperities is proposed to characterize the adhesion hysteresis. These will be helpful to understand and control the adhesion hysteresis for solid-solid contact.

Sign in / Sign up

Export Citation Format

Share Document