Role of Trabecular Bone Distribution in Femoral Neck Biomechanics

2000 ◽  
Author(s):  
Julia C. Fox ◽  
Tony M. Keaveny
Keyword(s):  
Femoral Neck ◽  
Cross Section ◽  
Bone Structure ◽  
Functional Adaptation ◽  
Asymmetric Distribution ◽  
Long Bones ◽  
Bone Mechanics ◽  
Area Of Interest ◽  
Potential Adaptation

Abstract Body weight, habitual postures and activities are the primary determinants of the nature and magnitude of loads acting on the proximal femur, the distribution of which influences the development of the bone structure and geometry (Wolff, 1892). This phenomena, called functional adaptation, has long been an area of interest in the field of bone mechanics, particularly with reference to compensatory geometric remodeling of long bones with decreasing bone mass (Martin et al. 1977; Ruff et al. 1988; Kannus et al., 1996). However, the extent to which compensatory remodeling occurs in the femoral neck remains unclear (Horikoshi, 1999; Beck, 1993). A potential adaptation of the femoral neck may be characterized by the asymmetric distribution of trabecular and cortical bone in the femoral neck cross-section, i.e. there is a disparity in superior and inferior cortical thickness (Bell, 1999; Boyce, 1993), referred to here as an eccentricity.

Oxygen K near edge structures studied with multiple scattering calculations

1988 ◽  
Vol 46 ◽  
pp. 504-505
Author(s):  
Xudong Weng ◽  
Peter Rez
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Partial Cross Section ◽  
Energy Window ◽  
Edge Structure ◽  
Fine Structures ◽  
Hydrogenic Model ◽  
Electron Energy Loss ◽  
Quantitative Chemical

In electron energy loss spectroscopy, quantitative chemical microanalysis is performed by comparison of the intensity under a specific inner shell edge with the corresponding partial cross section. There are two commonly used models for calculations of atomic partial cross sections, the hydrogenic model and the Hartree-Slater model. Partial cross sections could also be measured from standards of known compositions. These partial cross sections are complicated by variations in the edge shapes, such as the near edge structure (ELNES) and extended fine structures (ELEXFS). The role of these solid state effects in the partial cross sections, and the transferability of the partial cross sections from material to material, has yet to be fully explored. In this work, we consider the oxygen K edge in several oxides as oxygen is present in many materials. Since the energy window of interest is in the range of 20-100 eV, we limit ourselves to the near edge structures.

A technique for preparing semiconductor cross sections for both TEM and SEM analysis

1989 ◽  
Vol 47 ◽  
pp. 712-713
Author(s):  
Stanley J. Klepeis ◽  
J.P. Benedict ◽  
R.M Anderson
Keyword(s):  
Sample Preparation ◽  
Cross Section ◽  
Cross Sections ◽  
Sem Analysis ◽  
Preparation Technique ◽  
Ion Milling ◽  
Tem Analysis ◽  
Polished Cross Section ◽  
Area Of Interest ◽  
Polished Side

The ability to prepare a cross-section of a specific semiconductor structure for both SEM and TEM analysis is vital in characterizing the smaller, more complex devices that are now being designed and manufactured. In the past, a unique sample was prepared for either SEM or TEM analysis of a structure. In choosing to do SEM, valuable and unique information was lost to TEM analysis. An alternative, the SEM examination of thinned TEM samples, was frequently made difficult by topographical artifacts introduced by mechanical polishing and lengthy ion-milling. Thus, the need to produce a TEM sample from a unique,cross-sectioned SEM sample has produced this sample preparation technique.The technique is divided into an SEM and a TEM sample preparation phase. The first four steps in the SEM phase: bulk reduction, cleaning, gluing and trimming produces a reinforced sample with the area of interest in the center of the sample. This sample is then mounted on a special SEM stud. The stud is inserted into an L-shaped holder and this holder is attached to the Klepeis polisher (see figs. 1 and 2). An SEM cross-section of the sample is then prepared by mechanically polishing the sample to the area of interest using the Klepeis polisher. The polished cross-section is cleaned and the SEM stud with the attached sample, is removed from the L-shaped holder. The stud is then inserted into the ion-miller and the sample is briefly milled (less than 2 minutes) on the polished side. The sample on the stud may then be carbon coated and placed in the SEM for analysis.

scholarly journals Kindlin-2 mediates mechanotransduction in bone by regulating expression of Sclerostin in osteocytes

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Lei Qin ◽  
Xuekun Fu ◽  
Jing Ma ◽  
Manxia Lin ◽  
Peijun Zhang ◽  
...  
Keyword(s):  
Bone Loss ◽  
Mechanical Stimulation ◽  
Fluid Shear Stress ◽  
Weight Bearing ◽  
Underlying Mechanism ◽  
Long Bones ◽  
Cell Orientation ◽  
Cytoskeleton Organization

AbstractOsteocytes act as mechanosensors in bone; however, the underlying mechanism remains poorly understood. Here we report that deleting Kindlin-2 in osteocytes causes severe osteopenia and mechanical property defects in weight-bearing long bones, but not in non-weight-bearing calvariae. Kindlin-2 loss in osteocytes impairs skeletal responses to mechanical stimulation in long bones. Control and cKO mice display similar bone loss induced by unloading. However, unlike control mice, cKO mice fail to restore lost bone after reloading. Osteocyte Kindlin-2 deletion impairs focal adhesion (FA) formation, cytoskeleton organization and cell orientation in vitro and in bone. Fluid shear stress dose-dependently increases Kindlin-2 expression and decreases that of Sclerostin by downregulating Smad2/3 in osteocytes; this latter response is abolished by Kindlin-2 ablation. Kindlin-2-deficient osteocytes express abundant Sclerostin, contributing to bone loss in cKO mice. Collectively, we demonstrate an indispensable novel role of Kindlin-2 in maintaining skeletal responses to mechanical stimulation by inhibiting Sclerostin expression during osteocyte mechanotransduction.

scholarly journals Does vitamin D supplementation prevent SARS-CoV-2 infection in military personnel? Review of the evidence

2021 ◽  
pp. bmjmilitary-2020-001686
Author(s):  
Iain T Parsons ◽  
R M Gifford ◽  
M J Stacey ◽  
L E Lamb ◽  
M K O'Shea ◽  
...  
Keyword(s):  
Vitamin D ◽  
Vitamin D Supplementation ◽  
Vitamin D Status ◽  
Military Studies ◽  
Vitamin D Receptors ◽  
Area Of Interest ◽  
Military Populations ◽  
Tract Infections ◽  
Recruit Training

For most individuals residing in Northwestern Europe, maintaining replete vitamin D status throughout the year is unlikely without vitamin D supplementation and deficiency remains common. Military studies have investigated the association with vitamin D status, and subsequent supplementation, with the risk of stress fractures particularly during recruit training. The expression of nuclear vitamin D receptors and vitamin D metabolic enzymes in immune cells additionally provides a rationale for the potential role of vitamin D in maintaining immune homeostasis. One particular area of interest has been in the prevention of acute respiratory tract infections (ARTIs). The aims of this review were to consider the evidence of vitamin D supplementation in military populations in the prevention of ARTIs, including SARS-CoV-2 infection and consequent COVID-19 illness. The occupational/organisational importance of reducing transmission of SARS-CoV-2, especially where infected young adults may be asymptomatic, presymptomatic or paucisymptomatic, is also discussed.

scholarly journals History, Colonialism, and Archival Methods in Socio-Hydrological Scholarship: A Case Study of the Boerasirie Conservancy in British Guiana

World ◽  
2020 ◽  
Vol 1 (3) ◽  
pp. 205-215
Author(s):  
Joshua Mullenite
Keyword(s):  
Environmental History ◽  
Cross Section ◽  
Science And Technology Studies ◽  
Model Development ◽  
Human Geography ◽  
Hydrological Models ◽  
British Guiana ◽  
Current Role

In this article, I review a cross-section of research in socio-hydrology from across disciplines in order to better understand the current role of historical-archival analysis in the development of socio-hydrological scholarship. I argue that despite its widespread use in environmental history, science and technology studies, anthropology, and human geography, archival methods are currently underutilized in socio-hydrological scholarship more broadly, particularly in the development of socio-hydrological models. Drawing on archival research conducted in relation to the socio-hydrology of coastal Guyana, I demonstrate the ways in which such scholarship can be readily incorporated into model development.

scholarly journals Modeling plasma-based CO2conversion: crucial role of the dissociation cross section

2016 ◽  
Vol 25 (5) ◽  
pp. 055016 ◽  
Author(s):  
Annemie Bogaerts ◽  
Weizong Wang ◽  
Antonin Berthelot ◽  
Vasco Guerra
Keyword(s):  
Cross Section ◽  
Crucial Role ◽  
Dissociation Cross Section

History, Politics, Law

2021 ◽  
Keyword(s):  
Cross Section ◽  
Political Thought ◽  
International Institutions ◽  
The Political ◽  
Global Order ◽  
The World ◽  
History Of ◽  
And Gender ◽  
The Many

Historians of political thought and international lawyers have both expanded their interest in the formation of the present global order. History, Politics, Law is the first express encounter between the two disciplines, juxtaposing their perspectives on questions of method and substance. The essays throw light on their approaches to the role of politics and the political in the history of the world beyond the single polity. They discuss the contrast between practice and theory as well as the role of conceptual and contextual analyses in both fields. Specific themes raised for both disciplines include statehood, empires and the role of international institutions, as well as the roles of economics, innovation and gender. The result is a vibrant cross-section of contrasts and parallels between the methods and practices of the two disciplines, demonstrating the many ways in which both can learn from each other.

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