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Structure

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Title: Structure  
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Structure

The structure of a DNA molecule is essential to its function.

Structure is an arrangement and organization of interrelated elements in a material object or system, or the object or system so organized.[1] Material structures include man-made objects such as data structures in computer science and musical form. Types of structure include a hierarchy (a cascade of one-to-many relationships), a network featuring many-to-many Link (geometry)s, or a lattice featuring connections between components that are neighbors in space.

Contents

  • Load-bearing 1
  • Biological 2
  • Chemical 3
  • Musical 4
  • Social 5
  • Data 6
  • Software 7
  • Logical 8
  • Structuralism 9
  • See also 10
  • References 11
  • Further reading 12
  • External links 13

Load-bearing

Gothic quadripartite cross-ribbed vaults of the Saint-Séverin church in Paris

Buildings, aircraft, soap films, skeletons, anthills, beaver dams and salt domes are all examples of load-bearing structures. The results of construction are divided into buildings and nonbuilding structures, and make up the infrastructure of a human society. Built structures are broadly divided by their varying design approaches and standards, into categories including building structures, architectural structures, civil engineering structures and mechanical structures.

The effects of loads on physical structures are determined through structural analysis, which is one of the tasks of structural engineering. The structural elements can be classified as one-dimensional (ropes, struts, beams, arches), two-dimensional (membranes, plates, slab, shells, vaults), or three-dimensional (solid masses).[2]:2 The latter was the main option available to early structures such as Chichen Itza. A one-dimensional element has one dimension much larger than the other two, so the other dimensions can be neglected in calculations; however, the ratio of the smaller dimensions and the composition can determine the flexural and compressive stiffness of the element. Two-dimensional elements with a thin third dimension have little of either but can resist biaxial traction.[2]:2–3

The structure elements are combined in structural systems. The majority of everyday load-bearing structures are section-active structures like frames, which are primarily composed of one-dimensional (bending) structures. Other types are Vector-active structures such as trusses, surface-active structures such as shells and folded plates, form-active structures such as cable or membrane structures, and hybrid structures.[3]:134–136

Load-bearing biological structures such as bones, teeth, shells, and tendons derive their strength from a multilevel hierarchy of structures employing biominerals and proteins, at the bottom of which are collagen fibrils.[4]

Biological

Ribbon schematic of the 3D structure of the protein triosephosphate isomerase. The brown spirals are α-helices and the green arrows are β strands, the components of β-pleated sheets.

In population and ecosystem level. Usually, a higher-level structure is composed of multiple copies of a lower-level structure.

Structural biology is concerned with the biomolecular structure of macromolecules, particularly proteins and nucleic acids.[5] The function of these molecules is determined by their shape as well as their composition, and their structure has multiple levels. Protein structure has a four-level hierarchy. The primary structure is the sequence of amino acids that make it up. It has a peptide backbone made up of a repeated sequence of a nitrogen and two carbon atoms. The secondary structure consists of repeated patterns determined by hydrogen bonding. The two basic types are the α-helix and the β-pleated sheet. The tertiary structure is a back and forth bending of the polypeptide chain, and the quaternary structure is the way that tertiary units come together and interact.[6]

Chemical

A skeletal formula for dopamine

Chemical structure refers to both molecular geometry and electronic structure. The structure can be represented by a variety of diagrams called structural formulas. Lewis structures use a dot notation to represent the valence electrons for an atom; these are the electrons that determine the role of the atom in chemical reactions.[7]:71–72 Bonds between atoms can be represented by lines with one line for each pair of electrons that is shared. In a simplified version of such a diagram, called a skeletal formula, only carbon-carbon bonds and functional groups are shown.[8]

Atoms in a crystal have a structure that involves repetition of a basic unit called a unit cell. The atoms can be modeled as points on a lattice, and one can explore the effect of symmetry operations that include rotations about a point, reflections about a symmetry planes, and translations (movements of all the points by the same amount). Each crystal has a finite group, called the space group, of such operations that map it onto itself; there are 230 possible space groups.[9]:125–126 By Neumann's law, the symmetry of a crystal determines what physical properties, including piezoelectricity and ferromagnetism, the crystal can have.[10]:34–36,91–92,168–169

Musical

A motif from the Preludes by Chopin, Op. 28 no.6, bars 1–3

A large part of

  • (syllabus and reading list)

External links

Further reading

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References

See also

In early 20th-century and earlier thought, form often plays a role comparable to that of structure in contemporary thought. The neo-Kantianism of Ernst Cassirer (cf. his Philosophy of Symbolic Forms, completed in 1929 and published in English translation in the 1950s) is sometimes regarded as a precursor of the later shift to structuralism and poststructuralism.[27]

Structuralism

As a branch of philosophy, logic is concerned with distinguishing good arguments from poor ones. A chief concern is with the structure of arguments.[25] An argument consists of one or more premises from which a conclusion is inferred.[26] The steps in this inference can be expressed in a formal way and their structure analyzed. Two basic types of inference are deduction and induction. In a valid deduction, the conclusion necessarily follow from the premises, regardless of whether they are true or not. An invalid deduction contains some error in the analysis. An inductive argument claims that if the premises are true, the conclusion is likely.[26]

Logical

In software architecture, the structure of software is the way in which it is partitioned into interrelated components. A key structural issue is minimizing dependencies between these components. This makes it possible to change one component without requiring changes in others.[21]:3 The structure can be represented in diagrams such as the Control Structure Diagram and the Nassi–Shneiderman diagram.[22] Structural elements reflect the requirements of the application: for example, if the system requires a high fault tolerance, then a redundant structure is needed so that if a component fails it has backups.[23] A high redundancy is an essential part of the design of several systems in the Space Shuttle.[24]

Software

In solving a problem, a data structure is generally an integral part of the algorithm.[20]:5 In modern programming style, algorithms and data structures are encapsulated together in an abstract data type.[20]:ix

In pointer that links them together in a particular order.[17]:156 Out of these any number of other data structures can be created such as stacks, queues, trees and hash tables.[18][19]

In a singly linked list, each element has a data value and a pointer to the next element.

Data

A social structure is a pattern of relationships. They are social Structure and agency are two confronted theories about human behaviour. The debate surrounding the influence of structure and agency on human thought is one of the central issues in sociology. In this context, agency refers to the individual human capacity to act independently and make free choices. Structure here refers to factors such as social class, religion, gender, ethnicity, customs etc. that seem to limit or influence individual opportunities.

Social

In analogy to linguistic terminology, motifs and phrases can be combined to make complete musical ideas such as sentences and phrases.[13][14] A larger form is known as the period. One such form that was widely used between 1600 and 1900 has two phrases, an antecedent and a consequent, with a half cadence in the middle and a full cadence at the end providing punctuation.[15]:38–39 On a larger scale are single-movement forms such as the sonata form and the contrapuntal form, and multi-movement forms such as the symphony.[12]

:80[12]

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