scholarly journals Information Percolation

2010 ◽  
Vol 2 (1) ◽  
pp. 100-111 ◽  
Author(s):  
Darrell Duffie ◽  
Gaston Giroux ◽  
Gustavo Manso
Keyword(s):  
Rate Of Convergence ◽  
Explicit Solution ◽  
Common Interest ◽  
Cross Sectional ◽  
Individual Agent ◽  
Large Market ◽  
The Mean ◽  
The Cross ◽  
Over Time

We study the “percolation” of information of common interest through a large market as agents encounter and reveal information to each other over time. We provide an explicit solution for the dynamics of the cross-sectional distribution of posterior beliefs. We also show that convergence of the cross-sectional distribution of beliefs to a common posterior is exponential and that the rate of convergence does not depend on the size of the groups of agents that meet. The rate of convergence is merely the mean rate at which an individual agent is matched. (JEL D83)

Information Percolation in OTC Markets

Dark Markets ◽  
2012 ◽  
Author(s):  
Darrell Duffie
Keyword(s):  
Private Information ◽  
Information Structure ◽  
Common Interest ◽  
Basic Information ◽  
Random Matching ◽  
Cross Sectional ◽  
Over The Counter ◽  
The Cross ◽  
Release Of Information ◽  
Over Time

This chapter describes a simple model of the “percolation” of information of common interest through an over-the-counter market with many agents. It also includes an explicit solution for the cross-sectional distribution of posterior beliefs at each time. It begins with the basic information structure for the economy and the setting for search and random matching. It then shows how to solve the model for the dynamics of the cross-sectional distribution of information. The remainder of the chapter is devoted to market settings and to extensions of the model that handle public releases of information, the receipt of new private information over time, and the release of information among groups of more than two agents at a time.

scholarly journals Atrophy patterns in isolated subscapularis lesions

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Gernot Seppel ◽  
Andreas Voss ◽  
Daniel J. H. Henderson ◽  
Simone Waldt ◽  
Bernhard Haller ◽  
...  
Keyword(s):  
Muscle Atrophy ◽  
Area Ratio ◽  
Cross Sectional Area ◽  
Control Group ◽  
Sectional Area ◽  
Cross Sectional ◽  
Subscapularis Muscle ◽  
Mri Scans ◽  
The Mean ◽  
The Cross

Abstract Background While supraspinatus atrophy can be described according to the system of Zanetti or Thomazeau there is still a lack of characterization of isolated subscapularis muscle atrophy. The aim of this study was to describe patterns of muscle atrophy following repair of isolated subscapularis (SSC) tendon. Methods Forty-nine control shoulder MRI scans, without rotator cuff pathology, atrophy or fatty infiltration, were prospectively evaluated and subscapularis diameters as well as cross sectional areas (complete and upper half) were assessed in a standardized oblique sagittal plane. Calculation of the ratio between the upper half of the cross sectional area (CSA) and the total CSA was performed. Eleven MRI scans of patients with subscapularis atrophy following isolated subscapularis tendon tears were analysed and cross sectional area ratio (upper half /total) determined. To guarantee reliable measurement of the CSA and its ratio, bony landmarks were also defined. All parameters were statistically compared for inter-rater reliability, reproducibility and capacity to quantify subscapularis atrophy. Results The mean age in the control group was 49.7 years (± 15.0). The mean cross sectional area (CSA) was 2367.0 mm2 (± 741.4) for the complete subscapularis muscle and 1048.2 mm2 (± 313.3) for the upper half, giving a mean ratio of 0.446 (± 0.046). In the subscapularis repair group the mean age was 56.7 years (± 9.3). With a mean cross sectional area of 1554.7 mm2 (± 419.9) for the complete and of 422.9 mm2 (± 173.6) for the upper half of the subscapularis muscle, giving a mean CSA ratio of 0.269 (± 0.065) which was seen to be significantly lower than that of the control group (p < 0.05). Conclusion Analysis of typical atrophy patterns of the subscapularis muscle demonstrates that the CSA ratio represents a reliable and reproducible assessment tool in quantifying subscapularis atrophy. We propose the classification of subscapularis atrophy as Stage I (mild atrophy) in case of reduction of the cross sectional area ratio < 0.4, Stage II (moderate atrophy) in case of < 0.35 and Stage III (severe atrophy) if < 0.3.

scholarly journals Secular trends in weight, height and weight for height among children under 7 years in nine cities of China, 1975–2015: results from five repeated cross-sectional surveys

BMJ Open ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. e029201 ◽  
Author(s):  
Ya Qin Zhang ◽  
Hui Li ◽  
Hua Hong Wu ◽  
Xin Nan Zong
Keyword(s):  
Outcome Measures ◽  
Mean Value ◽  
Secular Trends ◽  
Healthy Children ◽  
Sample Sizes ◽  
Older Children ◽  
Cross Sectional ◽  
The Mean ◽  
Increasing Trends ◽  
Over Time

ObjectiveTo analyse the secular trends in mean value and distribution of weight, height and weight for height in children under 7 years in developed regions in China.DesignFive repeated cross-sectional surveys were conducted using the same methods at the same sites during 1975–2015.SettingNine cities in northern, central and southern regions of China.PopulationHealthy children under 7 years; the sample sizes were 94 496 in 1975, 79 177 in 1985, 79 152 in 1995, 69 760 in 2005 and 83 583 in 2015.Main outcome measuresWeight and height were measured by the same methods in the five surveys.ResultsThe increasing trends in the mean value of weight, height and weight for height were observed and their distribution was found to have shifted upwards. There were unbalanced increments in various centiles and the relative increments in the 3rd centile of height for children under 7 years were larger than those in the 50th and 97th centiles. Although the relative increments in the 3rd centile of weight for children under 2 years were larger than those in the 50th and 97th centiles, the increments in the 97th centile for children older than 2 years became the largest compared with other centiles. The changes in each centile of weight for height were similar with those of weight. The annual increments of height and weight increased over time and were more significant between birth and 2 years of age for height and between ages 4 years and 6 years for weight. The per-decade increments in 1975–1985, 1985–1995 and 1995–2005 became larger, while those in 2005–2015 slowed down.ConclusionsThe rapid increasing trends of weight, height and weight for height had slowed down since 2005 in developed regions of China. The relative increments in the low centile of height were more significant, while the high centile of weight and weight for height increased more significantly in older children.

scholarly journals The HIV/STI Epidemic Potential of Dynamic Sexual Networks of Men Who Have Sex With Men in Atlanta and San Francisco

2020 ◽  
Author(s):  
Emeli J. Anderson ◽  
Kevin M. Weiss ◽  
Martina M. Morris ◽  
Travis H. Sanchez ◽  
Pragati Prasad ◽  
...  
Keyword(s):  
San Francisco ◽  
Network Connectivity ◽  
Parameter Estimates ◽  
Sexual Networks ◽  
Age Group ◽  
Exponential Random Graph Models ◽  
Cross Sectional ◽  
The Cross ◽  
Over Time ◽  
Age Category

ABSTRACTBackgroundThe potential speed through which a pathogen may circulate in a network is a function of network connectivity. Network features like degree (number of ongoing partnerships) determine the cross-sectional network connectivity. The overall transmission potential of a pathogen involves connectivity over time, which can be measured using the forward reachable path (FRP). We modeled dynamic sexual networks of MSM in San Francisco and Atlanta to estimate the FRP as a predictor of HIV/STI epidemic potential.MethodsWe used exponential random graph models to obtain parameter estimates for each city’s sexual network and then simulated the complete networks over time. The FRP was estimated in each city overall and stratified by demographics.ResultsThe overall mean and median FRPs were higher in San Francisco than in Atlanta, suggesting a greater epidemic potential for HIV and STIs in San Francisco. At one year, in both cities, the average FRP among casual partnerships was highest in the youngest age group and lowest in the oldest age group, contrasting with the cross-sectional network parameters we estimated, where the youngest age category had the lowest mean degree and the oldest age category had the highest mean degree.ConclusionsThe FRP results correspond to the observed STI epidemics but not HIV epidemics between the cities. In San Francisco, rates of HIV have been declining over the last few years, whereas they have been steady in Atlanta. The FRP by age group resulted in fundamentally different conclusions about connectivity in the network compared with the cross-sectional network measures.

scholarly journals Recalcitrant betas: Intraday variation in the cross‐sectional dispersion of systematic risk

2021 ◽  
Vol 12 (2) ◽  
pp. 647-682 ◽  
Author(s):  
Torben G. Andersen ◽  
Martin Thyrsgaard ◽  
Viktor Todorov
Keyword(s):  
High Frequency ◽  
Opposite Effect ◽  
Functional Limit ◽  
Cross Sectional ◽  
Macroeconomic News ◽  
Market Index ◽  
Cross Sectional Dimension ◽  
Large Panel ◽  
The Cross ◽  
Over Time

We study the temporal behavior of the cross‐sectional distribution of assets' market exposure, or betas, using a large panel of high‐frequency returns. The asymptotic setup has the sampling frequency of returns increasing to infinity, while the time span of the data remains fixed, and the cross‐sectional dimension of the panel is either fixed or increasing. We derive functional limit results for the cross‐sectional distribution of betas evolving over time. We demonstrate, for constituents of the S&P 500 market index, that the dispersion in betas is elevated at the market open and gradually declines over the trading day. This intraday pattern varies significantly over time and reacts to information shocks such as clustered earning announcements and releases of macroeconomic news. We find that earnings news increase beta dispersion while FOMC announcements have the opposite effect on market betas.

scholarly journals Congenital pseudarthrosis of the tibia: biological and biomechanical considerations to achieve union and prevent refracture

2019 ◽  
Vol 13 (2) ◽  
pp. 120-133 ◽  
Author(s):  
D. Paley
Keyword(s):  
Bone Morphogenic Protein ◽  
Level Of Evidence ◽  
Cross Sectional ◽  
Congenital Pseudarthrosis ◽  
Proximal Migration ◽  
The Mean ◽  
The Cross ◽  
Both Bones ◽  
Primary Union ◽  
Biomechanical Factors

Congenital pseudarthrosis of the tibia (CPT) is likely to be a primary periosteal disease and secondary bone disease. The primary goal of treatment is to obtain union, correct the diaphyseal deformity, correct any proximal fibular migration and prevent refracture. The pathobiology demonstrates increased osteoclasis by the surrounding fibrous hamartoma and reduced osteogenesis and bone morphogenic protein production by the bone. This leads to a loss of remodelling potential and gradual bowing and atrophy of the bone with eventual fracture of the tibia and or fibula. This recommends the synergistic use of bisphosphonates and bone morphogenic protein. The pathomechanics of CPT implicate the anterolateral bowing, narrow diameter of the atrophic bone ends and proximal fibular migration. These biomechanical factors can be addressed by means of straightening of the deformity, intramedullary support of both bones, stable fixation and reduction of proximal migration of the fibula. A summary of the literature on CPT shows that the mean probability of achieving primary union without refracture, by most treatments is 50% (12% to 80%). Two recent studies have shown a much higher success rate approaching 100%, by creating a cross-union between the tibia and fibula. The cross-union with intramedullary reinforcement of the bone makes refracture unlikely due to the cross-sectional area of union with its two-bar linkage. A new classification to guide such treatment is also proposed. Level of Evidence V – expert opinion

Multivariate Model for Defining Changes in Maximal Physical Working Capacity of Men, Ages 25 to 70 Years

1992 ◽  
Vol 36 (2) ◽  
pp. 171-174 ◽  
Author(s):  
Andrew S. Jackson ◽  
Earl F. Beard ◽  
Larry T. Wier ◽  
J. E. Stuteville
Keyword(s):  
Physical Activity ◽  
Body Fat ◽  
Multivariate Model ◽  
Percent Body Fat ◽  
Physical Working Capacity ◽  
Working Capacity ◽  
Cross Sectional ◽  
Exercise Habits ◽  
The Cross ◽  
Over Time

The purpose of this study was to develop a multivariate model with cross-sectional data that defined the decline in VO2max over time, and cross-validate the model with longitudinal data. The cross-sectional sample consisted of 1,608 healthy men who ranged in age from 25 to 70 years. VO2max was directly measured during a maximum Bruce treadmill stress test. Regression analysis showed that the cross-sectional age and VO2max relationship was linear, r = 0.45 and the age decline in VO2max was 0.48 ml/kg/min/year. Multiple regression developed the multivariate model from age, percent body fat (%fat), self-report physical activity (SR-PA), and the interaction of SR-PA and %fat (R = 0.793). Accounting for the variance in percent body fat and exercise habits decreased the influence of age on the decline of VO2max to just −0.27 ml/kg/min/year. This showed that much of decline in maximal physical working capacity was due to physical activity level and percent body fat, not aging. The multivariate equation was applied to the data of the longitudinal sample of 156 men who had been tested twice (Mean AgeΔ = 3.1 ± 1.2 years). The correlation between the measured and estimated change in VO2max over time (ΔVO2max) was 0.75. The results of the study showed that changes in body composition and exercise habits had more of an influence on changes in maximal physical working capacity than aging. The developed model provides a useful way to quantify the changes in physical working capacity with aging.

scholarly journals Cross Sectional Area of the Achilles Tendon in a Prospective Cohort of an Elite Military Population

2017 ◽  
Vol 2 (3) ◽  
pp. 2473011417S0002
Author(s):  
Kevin Martin ◽  
Laura Dawson ◽  
Jeffrey Wake
Keyword(s):  
Achilles Tendon ◽  
Prospective Cohort ◽  
Military Training ◽  
Cross Sectional Area ◽  
Service Members ◽  
Sectional Area ◽  
Cross Sectional ◽  
The Mean ◽  
Multiple Levels ◽  
The Cross

Category: Ankle, Hindfoot Introduction/Purpose: The prevalence of Achilles tendon pathology is common in many sports and daily activities. From ruptures to overuse injuries resulting in tendonopathies, AT dysfunction can result in disability and reduced productively. Continued research that increases our knowledge base of normal Achilles tendon properties can improve our ability to reduce and prevent future AT injuries. In this study, we examined the cross-sectional area (CSA) of the Achilles tendon (AT) at multiple levels in an asymptomatic population of elite American military service members that participate in greater than 20 hours of intense training per week. Methods: We conducted a prospective cohort study composed of 41 active duty United States Army Rangers. The Rangers are a specialized infantry organization that participates in extensive military training and rigorous combat missions. The service members were voluntarily recruited to participate while deployed in a combat theater. All subjects were members of the Ranger Regiment participating in greater than 20 hours of intense bipedal non-sport weekly training with no history of AT pathology. In a standing position, each subject had bilateral Achilles insertion marked along with additional skin markings made at 2 cm, 4 cm, and 6 cm above the AT insertion. At all four levels, the AT was measured in the coronal and sagittal plains using ultrasound. Results: In 41 subjects, a total of 82 Achilles tendons were examined. The mean age of the cohort was 26 years, 70 inches tall, with a mean weight of 187 pounds. The mean sagittal thickness of the AT at the insertion was 4.3 mm, 2 cm above the insertion is was 4.3 mm, 4 cm above the insertion is was 4.2 mm, and at 6 cm above the insertion it was 4 mm. In the coronal plain was 19.1 mm, 14.3 mm, 13.5 mm, and 14.4 mm respectively. The cross-sectional area was calculated at each respective level: 0.65 cm2, 0.48 cm2, 0.44 cm2 and 0.45 cm2. The non-dominant ankle was slightly larger at each level but was not found to be statistically significant. Conclusion: These results provide the mean sagittal and coronal diameters of the Achilles tendon as measured by ultrasound throughout the watershed area of a young active adult male population. Our data also suggest that increased non-sport activity may not increase the cross-sectional area of the Achilles tendon. Identifying the normal diameter at multiple levels throughout the most commonly injured area can potentially improve the provider’s ability to identify early disease processes and apply targeted interventions to help slow or prevent progression and possible rupture.

scholarly journals Effects of Wet-Pressing and Cross-Linking on the Tensile Properties of Carbon Nanotube Fibers

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2170 ◽  
Author(s):  
Hyunjung Cho ◽  
Jinwoo Lee ◽  
Haemin Lee ◽  
Sung-Hyun Lee ◽  
Junbeom Park ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Cross Linking ◽  
Cross Sectional ◽  
Specific Strength ◽  
Wet Pressing ◽  
Mean Size ◽  
The Mean ◽  
The Cross ◽  
Carbon Nanotube Fibers ◽  
Physical And Chemical

To increase the strength of carbon nanotube (CNT) fibers (CNTFs), the mean size of voids between bundles of CNTs was reduced by wet-pressing, and the CNTs were cross-linked. Separate and simultaneous physical (roller pressing) and chemical methods (cross-linking) were tested to confirm each method’s effects on the CNTF strength. By reducing the fraction of pores, roller pressing decreased the cross-sectional area from 160 μm2 to 66 μm2 and increased the average load-at-break from 2.83 ± 0.25 cN to 4.41 ± 0.16 cN. Simultaneous injection of crosslinker and roller pressing augmented the cross-linking effect by increasing the infiltration of the crosslinker solution into the CNTF, so the specific strength increased from 0.40 ± 0.05 N/tex to 0.67 ± 0.04 N/tex. To increase the strength by cross-linking, it was necessary that the size of the pores inside the CNTF were reduced, and the infiltration of the solution was increased. These results suggest that combined physical and chemical treatment is effective to increase the strength of CNTFs.

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