scholarly journals Biomechanics of the Canine Mandible During Bone Transport Distraction Osteogenesis

2014 ◽  
Vol 136 (11) ◽  
Author(s):  
Uriel Zapata ◽  
Paul C. Dechow ◽  
Ikuya Watanabe ◽  
Mohammed E. Elsalanty ◽  
Lynne A. Opperman

This study compared biomechanical patterns between finite element models (FEMs) and a fresh dog mandible tested under molar and incisal physiological loads in order to clarify the effect of the bone transport distraction osteogenesis (BTDO) surgical process. Three FEMs of dog mandibles were built in order to evaluate the effects of BTDO. The first model evaluated the mandibular response under two physiological loads resembling bite processes. In the second model, a 5.0 cm bone defect was bridged with a bone transport reconstruction plate (BTRP). In the third model, new regenerated bony tissue was incorporated within the defect to mimic the surgical process without the presence of the device. Complementarily, a mandible of a male American foxhound dog was mechanically tested in the laboratory both in the presence and absence of a BTRP, and mechanical responses were measured by attaching rosettes to the bone surface of the mandible to validate the FEM predictions. The relationship between real and predicted values indicates that the stress patterns calculated using FEM are a valid predictor of the biomechanics of the BTDO procedures. The present study provides an interesting correlation between the stiffness of the device and the biomechanical response of the mandible affected for bone transport.

Author(s):  
З.С. САНОВА

В статье представлены материалы о взаимосвязи продолжительности продуктивного использования коров с характеристикой устойчивости к деградации, с возрастом отела и удоем. В исследованной, разнородной по происхождению, группе животных для прогноза продуктивного периода коров, обусловленного устойчивостью к деградации и возрастом первого отела, пригодно уравнение регрессии, аргументами в котором являются индекс устойчивости, возраст первого отела в первой и второй степенях. Коэффициент корреляции межу предсказанными значениями продуктивного периода и его фактическими величинами в I группе составляет 0,502, во II - 0,604. При этом крайние варианты прогнозируются со статистическими ошибками 5 мес при оценке индекса устойчивости по 2 лактациям и 4,1 мес по 3, а средние варианты, соответственно, 1,6 и 1,51 мес. Индекс устойчивости к процессу старения является важной характеристикой биологических особенностей коров, определяющий их продуктивное долголетие. Его оценка по первым 2 и 3 лактациям имеет прямолинейную связь с продуктивным периодом (r=0,4109 и r=0,5270), соответственно. Зависимость продуктивного периода от возраста первого отела криволинейная — с увеличением возраста первого отела сокращается срок продуктивного использования, при возрасте первого отела более 1400 дней срок продуктивного использования колеблется от 1,33 до 1,41 лактации. Коэффициент корреляции между этими характеристиками коров составляет - 0,2164 в I и - 0,2620 во II группах. The article presents materials about the relationship of the duration of productive use of cows with the characteristic of resistance to degradation, with the age of calving and milk yield. In the studied group of animals, which is heterogeneous in origin, the regression equation is suitable for predicting the productive period of cows due to resistance to degradation and the age of the first calving, the arguments of which are the stability index, the age of the first calving in the first and second degrees. The correlation coefficient between the predicted values of the productive period and its actual values in group I is 0.502, in group II - 0.604. At the same time, the extreme variants are predicted with statistical errors of 5 months when evaluating the stability index for 2 lactations and 4.1 months for 3, and the average variants, respectively, are 1.6 and 1.51 months. The index of resistance to the aging process is an important characteristic of the biological characteristics of cows, which determines their productive longevity. Its estimate for the first 2 and 3 lactations has a direct relationship with the productive period (r=0.4109 and r=0.5270), respectively. The dependence of the productive period age at first calving curvilinear with increasing age at first calving reduces the time to productive use, while age at first calving of more than 1400 days, the period of productive use ranges from 1.33 to 1.41 lactation. The correlation coefficient between these characteristics of cows is-0.2164 in I and-0.2620 in II groups.


2021 ◽  
Vol 11 (9) ◽  
pp. 4039
Author(s):  
Yiran Niu ◽  
Lin Li ◽  
Yanwei Zhang ◽  
Shicai Yu ◽  
Jian Zhou

Contact breakage of particles makes a large difference in the strength of coarse-grained soils, and exploring the characteristics within the process of the breakage is of great significance. Ignoring the influence of particle shape, the micromechanism of two spherical particles breaking under normal–tangential contact conditions was investigated theoretically and experimentally. Through theoretical analysis, the breakage form, the shape and size of the conical core, and the relationship between the normal and tangential forces at crushing were predicted. Particle contact tests of two gypsum spheres were carried out, in which the breakage forms, features of the conical cores and the normal and tangential forces at crushing were recorded for comparison with the predicted values. The test results and the theoretical predictions showed good agreement. Both the analysis and test demonstrate that the presence of tangential forces causes the conical core to assume the shape of an oblique cone, and the breakage form to change. Moreover, with increasing normal contact force, the tangential force needed for crushing increases gradually first and then decreases suddenly.


2017 ◽  
Vol 6 (4) ◽  
pp. 52
Author(s):  
Izhar Haq ◽  
Teresa Lang ◽  
Hongkang Xu

This study uses GMI Ratings directorship data from 2008 to 2013 along with the associated financial data to examine the relationship between audit committee chair change with the absolute discretionary accruals in the financial statements of the reporting companies.  Our results suggest that audit committee chair change is positively associated with the absolute discretionary accruals.  Specifically, absolute discretionary accruals are significantly higher when there is a change in the audit committee chair.  These results are consistent with prior research that deviations from the predicted values of accruals is an indicator of “poor” audit quality.  An additional finding of this paper is that a person younger than 60 is more likely to be a new audit committee chair when there is a change and therefore will have less experience and contacts than the outgoing chair. An important implication of these results is that audit committee chair change can have a significant impact on the quality of the financial statements of a company as well as on the audit quality.


2020 ◽  
Vol 4 (Supplement_1) ◽  
pp. 592-593
Author(s):  
Francesca Falzarano ◽  
Karen Siedlecki ◽  
Jillian Minahan

Abstract Research examining the relationship between subjective cognitive complaints and objective cognitive performance has been mixed. Despite the lack of clear evidence demonstrating an association, subjective cognitive complaints are used as a criterion for the diagnosis of mild cognitive impairment and is considered a risk factor for Alzheimer’s disease. Cross-lagged panel analyses were used in the current study to examine the longitudinal relationships between subjective cognitive complaints (using the Memory Functioning Questionnaire) and objective cognition (e.g., reasoning, memory, spatial visualization, processing speed, and vocabulary) in healthy adults over 60 from the Virginia Cognitive Aging Project (N=441). Results indicated that objective and subjective cognition were only weakly related but that objective cognition is a stronger predictor of subjective cognitive complaints then vice versa. Although subjective cognitive complaints may be an early indicator of pathological aging, results indicate that subjective cognitive complaints may not be a valid predictor of objective cognitive decline.


2018 ◽  
Vol 8 (1) ◽  
pp. 108-133 ◽  
Author(s):  
Jessica DeLisi

AbstractThis paper examines the relationship between typology and historical linguistics through a case study from the history of Armenian, where two different stress systems are found in the modern language. The first is a penult system with no associated secondary stress ([… σ́σ]ω). The other, the so-called hammock pattern, has primary stress on the final syllable and secondary stress on the initial syllable of the prosodic word ([σ̀ … σ́]ω). Although penult stress patterns are by far more typologically common than the hammock pattern in the world’s languages, I will argue that the hammock pattern must be reconstructed for the period of shared innovation, the Proto-Armenian period.


2020 ◽  
Vol 84 (5S) ◽  
pp. S202-S207 ◽  
Author(s):  
Abulaiti Abula ◽  
Maimaiaili Yushan ◽  
Peng Ren ◽  
Alimujiang Abulaiti ◽  
Chuang Ma ◽  
...  

Author(s):  
Baptiste Coudrillier ◽  
Kristin M. Myers ◽  
Thao D. Nguyen

By 2010, 60 million people will have glaucoma, the second leading cause of blindness worldwide [1]. The disease is characterized by a progressive degeneration of the retinal ganglion cells (RGC), a type of neuron that transmits visual information to the brain. It is well know that elevated intraocular pressure (IOP) is a risk factor in the damage to the RGCs [3–5], but the relationship between the mechanical properties of the ocular connective tissue and how it affects cellular function is not well characterized. The cornea and the sclera are collage-rich structures that comprise the outer load-bearing shell of the eye. Their preferentially aligned collagen lamellae provide mechanical strength to resist ocular expansion. Previous uniaxial tension studies suggest that altered viscoelastic material properties of the eye wall play a role in glaucomatous damage [6].


2010 ◽  
Vol 89-91 ◽  
pp. 165-170
Author(s):  
Guillaume Dubois ◽  
Anne Sophie Bonnet ◽  
Paul Lipiński

Distraction Osteogenesis (DO) is a surgical technique used to reconstruct bone defects. In the maxillofacial specialty, it account for one of the best procedures to treat severe traumas as ballistic wounds. The evolution of forces acting during DO is known to be strongly linked with the clinical issue of the treatment. In this context, the aim of this study was to determine the time-dependent forces supported by a distraction device (DEOS, OBL, France), particularly indicated for severe traumas. Bone transport forces were evaluated for two patients undergoing respectively mandibular and malar DO following a gunshot wound. In order to evaluate the distraction forces, some fixing pins of the distraction device were equipped with strain gauges. Strain values were recorded by means of a data acquisition system (SCXI, National Instruments, USA) connected to a PC computer and executing a LabView program (National Instruments, USA). Records started about one minute before the DO activation and ended about one hour later. Eighteen measurements were done for both cases during the early phases of the treatment. An equilibrium analysis was achieved in order to determine the force and moment acting in bone regenerate from strains in the pins. This procedure was coded through a Fortran program, allowing to plot the evolution of DO force and moment. The present work confirmed the time-dependent feature of the bone regenerate mechanical behaviour. Important data have been obtained concerning forces and their evolution for both mandibular and malar DO.


2011 ◽  
Vol 89 (5) ◽  
pp. 379-388 ◽  
Author(s):  
Uriel Zapata ◽  
Emily K. Halvachs ◽  
Paul C. Dechow ◽  
Mohammed E. Elsalanty ◽  
Lynne A. Opperman

2005 ◽  
Vol 90 (9) ◽  
pp. 5118-5120 ◽  
Author(s):  
M. Janet Barger-Lux ◽  
Robert P. Heaney

Abstract Background: Calcium absorption efficiency is a more important determinant of calcium balance than calcium intake itself. The sources of variability in absorptive performance are only partly elucidated. Purpose: The aim of the study was to explore the relationship between body size and calcium absorption efficiency. Design and Setting: Metabolic studies were performed on an inpatient metabolic unit in an academic health sciences center. Subjects: One hundred seventy-eight women, with an average age of 50.2 yr, were studied from one to five times and yielded an aggregate data set containing 633 individual studies. Methods: Calcium absorption fraction was measured by the dual-tracer method. Observed values were expressed as residuals from predicted values for each woman’s actual calcium intake, using the previously published relationship between intake and absorption. Results: Absorption residuals were significantly positively correlated with height, weight, and surface area, and after adjusting for estrogen status, these body size variables accounted for approximately 4% of the total variability. Conclusion: The magnitude of the effect is such that a woman 1.8 m in height would absorb 30+% more calcium from a given intake than a woman 1.4 m tall.


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