How Is a Tissue Built?1

2000 ◽  
Vol 122 (6) ◽  
pp. 553-569 ◽  
Author(s):  
Stephen C. Cowin
Keyword(s):  
Developmental Biology ◽  
Living Organism ◽  
Tissue Structure ◽  
Structural Function ◽  
Biological Processes ◽  
Mechanical Environment ◽  
Structural Patterns ◽  
Know How ◽  
New Ideas ◽  
Living Tissues

Tissues change in many ways in the period that they are part of a living organism. They are created in fairly repeatable structural patterns, and we know that the patterns are due to both the genes and the (mechanical) environment, but we do not know exactly what part or percentage of a particular pattern to consider the genes, or the environment, responsible for. We do not know much about the beginning of tissue construction (morphogenesis) and we do not know the methods of tissue construction. When the tissue structure is altered to accommodate a new loading, we do not know how the decision is made for the structural reconstruction. We do know that tissues grow or reconstruct themselves without ceasing to continue with their structural function, but we do not understand the processes that permit them to accomplish this. Tissues change their structures to altered mechanical environments, but we are not sure how. Tissues heal themselves and we understand little of the structural mechanics of the process. With the objective of describing the interesting unsolved mechanics problems associated with these biological processes, some aspects of the formation, growth, and adaptation of living tissues are reviewed. The emphasis is on ideas and models. Beyond the objective is the hope that the work will stimulate new ideas and new observations in the mechanical and chemical aspects of developmental biology. [S0148-0731(00)00106-0]

scholarly journals The Spread of Information in Virtual Communities

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Zhen Zhang ◽  
Jin Du ◽  
Qingchun Meng ◽  
Xiaoxia Rong ◽  
Xiaodan Fan
Keyword(s):  
Network Theory ◽  
Virtual Communities ◽  
Coefficient Of Determination ◽  
Jaccard Coefficient ◽  
Online Commerce ◽  
Know How ◽  
Random Forest Method ◽  
Key Points ◽  
New Ideas ◽  
Physical Features

With the growth of online commerce, companies have created virtual communities (VCs) where users can create posts and reply to posts about the company’s products. VCs can be represented as networks, with users as nodes and relationships between users as edges. Information propagates through edges. In VC studies, it is important to know how the number of topics concerning the product grows over time and what network features make a user more influential than others in the information-spreading process. The existing literature has not provided a quantitative method with which to determine key points during the topic emergence process. Also, few researchers have considered the link between multilayer physical features and the nodes’ spreading influence. In this paper, we present two new ideas to enrich network theory as applied to VCs: a novel application of an adjusted coefficient of determination to topic growth and an adjustment to the Jaccard coefficient to measure the connection between two users. A two-layer network model was first used to study the spread of topics through a VC. A random forest method was then applied to rank various factors that might determine an individual user’s importance in topic spreading through a VC. Our research provides insightful ways for enterprises to mine information from VCs.

Mechanoresponsive self-growing hydrogels inspired by muscle training

Science ◽  
2019 ◽  
Vol 363 (6426) ◽  
pp. 504-508 ◽  
Author(s):  
Takahiro Matsuda ◽  
Runa Kawakami ◽  
Ryo Namba ◽  
Tasuku Nakajima ◽  
Jian Ping Gong
Keyword(s):  
Polymeric Materials ◽  
Muscle Training ◽  
Reconstruction Process ◽  
Mechanical Environment ◽  
Double Network ◽  
Synthetic Materials ◽  
Mechanochemical Transduction ◽  
Repetitive Loading ◽  
Intelligent Devices ◽  
Living Tissues

Living tissues, such as muscle, autonomously grow and remodel themselves to adapt to their surrounding mechanical environment through metabolic processes. By contrast, typical synthetic materials cannot grow and reconstruct their structures once formed. We propose a strategy for developing “self-growing” polymeric materials that respond to repetitive mechanical stress through an effective mechanochemical transduction. Robust double-network hydrogels provided with a sustained monomer supply undergo self-growth, and the materials are substantially strengthened under repetitive loading through a structural destruction-reconstruction process. This strategy also endows the hydrogels with tailored functions at desired positions by mechanical stamping. This work may pave the way for the development of self-growing gel materials for applications such as soft robots and intelligent devices.

A Novel Experimental Technique for Quantifying the Local Mechanical Environment of Skeletal Tissues

2007 ◽  
Author(s):  
Kristy T. S. Palomares ◽  
Gregory J. Miller ◽  
Louis C. Gerstenfeld ◽  
Thomas A. Einhorn ◽  
Elise F. Morgan
Keyword(s):  
Experimental Technique ◽  
Tissue Level ◽  
Biological Processes ◽  
Mechanical Stimuli ◽  
Mechanical Environment ◽  
Organ Level ◽  
Shear Motion ◽  
Healing Bone ◽  
Tissue Material

A growing body of evidence indicates that mechanical cues modulate the development and repair of skeletal tissues by regulating gene expression and tissue differentiation.[1–3] Further understanding of how the mechanical environment modulates these biological processes could be applied to enhance skeletal repair following injury or disease. Bone healing provides an excellent in vivo system for investigating cellular responses to mechanical stimuli, due to the recruitment of pluripotent, mechano-sensitive, mesenchymal stem cells. For example, recent studies have shown that bending and/or shear motion applied to a healing bone defect can result in cartilage rather than bone formation.[4,5] However, while different global (i.e. organ level) mechanical stimuli are known to result in different healing outcomes, the specific local (i.e. tissue level) stimuli that promote different tissue fates have yet to be established. Finite element analyses can provide estimates of these local stimuli, yet these analyses require many assumptions regarding tissue material properties and boundary conditions. Our overall goal in this study was to develop an experimental technique for quantifying the distributions of local strains that develop in skeletal tissues during mechanical loading.

The Mechanism of Personality

1931 ◽  
Vol 77 (319) ◽  
pp. 708-722
Author(s):  
W. Burridge
Keyword(s):  
Ad Hoc ◽  
Scientific Practice ◽  
The Body ◽  
The Other ◽  
Body Work ◽  
Fundamental Properties ◽  
Peculiar Behaviour ◽  
New Knowledge ◽  
New Ideas ◽  
Living Tissues

Our conceptions of how the organs of the body work are primarily derived from experiments done on muscle, the organ from which experimenters have been accustomed over many decades to ascertain the fundamental properties of living tissues; the principles there learnt have then been directly applied to the problems presented by other organs. Such having been, and still being, scientific practice, it follows that, if we find out about the working of muscle something fundamentally different from that hitherto suspected, we not only obtain therefrom new ideas of the working of muscle, but also new principles to apply to our ideas of the working of other organs. It could happen, however, that new knowledge concerning the fundamental working of the organs of the body should actually come from some other organ than muscle. In that case the newly discovered phenomena would not be directly explicable in terms of the fundamental principles derived from muscle. Two courses would then be possible. The discoverer could re-consider his fundamental principles, and thereby be led to reexamine the workings of muscle in the light of the information supplied by the other organ, or he could frame an ad hoc hypothesis concerning the supposed peculiar behaviour of the other organ. The latter has been the usual course followed, though it would not appear that the framing of such hypotheses has been made with full awareness that they really resolve conflict between principles derived from muscle and principles derived from the other organ.

scholarly journals The physics of life: one molecule at a time

2013 ◽  
Vol 368 (1611) ◽  
pp. 20120248 ◽  
Author(s):  
Mark C. Leake
Keyword(s):  
Single Molecule ◽  
Molecular Motors ◽  
Living Organism ◽  
Biological Processes ◽  
Robust Methods ◽  
Erwin Schrödinger ◽  
Biophysical Analysis ◽  
Spatial Boundary ◽  
New Generation ◽  
Near Future

The esteemed physicist Erwin Schrödinger, whose name is associated with the most notorious equation of quantum mechanics, also wrote a brief essay entitled ‘What is Life?’, asking: ‘How can the events in space and time which take place within the spatial boundary of a living organism be accounted for by physics and chemistry?’ The 60+ years following this seminal work have seen enormous developments in our understanding of biology on the molecular scale, with physics playing a key role in solving many central problems through the development and application of new physical science techniques, biophysical analysis and rigorous intellectual insight. The early days of single-molecule biophysics research was centred around molecular motors and biopolymers, largely divorced from a real physiological context. The new generation of single-molecule bioscience investigations has much greater scope, involving robust methods for understanding molecular-level details of the most fundamental biological processes in far more realistic, and technically challenging, physiological contexts, emerging into a new field of ‘single-molecule cellular biophysics’. Here, I outline how this new field has evolved, discuss the key active areas of current research and speculate on where this may all lead in the near future.

scholarly journals Measuring forces and stresses in situ in living tissues

2015 ◽  
Author(s):  
Forces-in-tissue workshop participants
Keyword(s):  
Mechanical Properties ◽  
Developmental Biology ◽  
Tissue Mechanics ◽  
Mechanical Measurements ◽  
Living Tissues ◽  
Near Future

Development, homeostasis and regeneration of tissues result from the interaction of genetics and mechanics. Kinematics and rheology are two main classes of measurements respectively providing deformations and mechanical properties of a material. They are now applied to living tissues and have contributed to the better understanding of their mechanics. Due to the complexity of living tissues, however, a third class of mechanical measurements, that of in situ forces and stresses, appears to be increasingly important to elaborate realistic models of tissue mechanics. We review here several emerging techniques of this class, their fields of applications, their advantages and limitations, and their validations. We argue that they will strongly impact on our understanding of developmental biology in the near future.

Capturing Processes

2018 ◽  
Author(s):  
Laura Nuño de la Rosa
Keyword(s):  
Developmental Biology ◽  
Quantitative Imaging ◽  
Time Lapse ◽  
First Century ◽  
Biological Processes ◽  
In Vivo Microscopy ◽  
Developmental Processes ◽  
Biological Entities ◽  
Time Lapse Imaging

While a processual view of biological entities might be said to be congenial to embryologists, the intractability and speed of developmental processes traditionally led to an epistemological abandon of processes in favour of the advantages of discretizing ontogenies in arrays of patterns. It is not until the turn of the twenty-first century that the digital embryos obtained from in vivo microscopy have started to replace developmental series as the reference representations of development. This chapter looks at how new microscopy, molecular, and computer technologies for reconstructing biological processes are contributing to a processual understanding of development. First it investigates how time-lapse imaging has brought with it a radical dynamization, not only of the images, but also of the theories of development themselves. Next it explores the role that imaging technologies have played in the return of organicism in developmental biology. Finally, it focuses on how quantitative imaging contributes to the explanatory modelling of developmental processes.

scholarly journals ULTRAFILTRATION THROUGH COLLODION MEMBRANES

1926 ◽  
Vol 9 (6) ◽  
pp. 813-826 ◽  
Author(s):  
Arthur Grollman
Keyword(s):  
Experimental Evidence ◽  
Pore Size ◽  
Living Organism ◽  
Living Cells ◽  
Active Materials ◽  
Surface Active ◽  
Living Tissues ◽  
Variable Layer ◽  
Effective Pore Size

It is obvious that the factors considered in this paper render data obtained by ultrafiltration open to criticism unless they are checked by other methods and precautions are taken for the elimination of the vitiating effects which have been described. As regards the mechanism of ultrafiltration, the view of a sieve-like action as most experimental evidence indicates, is adequate, if all the factors are considered which might modify the effective pore size. The behaviors of collodion membranes which seem contrary to a mechanism of ultrafiltration based on the existence of a system of pores, can be explained on the basis of a variable layer of adsorbed fluid on the walls of the pores. It is, therefore, unsound to make any deductions about living tissues from the demonstration of changes produced in the behavior of collodion membranes. Thus, the increase in the rate of filtration of water through collodion by diuretics (29) or the change of permeability due to the presence of surface-active materials, gives us no information about their action in the living organism. The effect of these substances on a sieve-like membrane of the type of collodion would not necessarily bear any analogy to that exerted on the emulsion type of membrane of living cells. The mechanisms of the reactions necessary to produce the same effects in such widely differing systems may be entirely unrelated.

scholarly journals Model Based Drafting

2019 ◽  
pp. 204-209
Author(s):  
Wolfgang List
Keyword(s):  
Design Process ◽  
Iterative Process ◽  
Know How ◽  
Model Based ◽  
New Ideas

Drafting and designing in architecture involve an iterative process of testing and comparing architectural thoughts and ideas. The goal of this iterative process is to find the best of several possible solutions, at each stage of the design process. To bring these architectural thoughts and ideas to reality designers need tools. Tools for discussing ideas and writing, sketching, plan drawing and model making for explaining, documenting and testing thoughts. But do the users of these tools, the designers, really know how these tools work or do the designers use these tools only out of habit? Some tools are already known for how they transport ideas, other tools are used out of behaviour without understanding their deeper impact on transporting thoughts and generating new ideas.

scholarly journals Tissue engineering: Designing for health

2003 ◽  
Vol 25 (5) ◽  
pp. 19-21
Author(s):  
Tim Hardingham
Keyword(s):  
Tissue Engineering ◽  
Biomedical Research ◽  
Gain Control ◽  
Living Cells ◽  
Scientific Understanding ◽  
Biological Processes ◽  
Research Groups ◽  
Living Tissues

The tissue engineering that is now emerging in biomedical research groups is concerned with living tissues and how we can harness biological processes to achieve healing and repair, where it is otherwise failing. It aims to develop our scientific understanding of how living cells function, so that we can gain control and direct their activity to the promote the repair of damaged and diseased tissue1.

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