ATOMIC MAGNETISM; THE BOHR MAGNETON; THE STERN-GERLACH EXPERIMENT; MAGNETISM AND TEMPERATURE; THE MAGNETO-MECHANICAL EFFECT

2011 ◽  
pp. 25-33
Author(s):  
George Birtwistle
Keyword(s):  
Mechanical Effect ◽  
Bohr Magneton

scholarly journals Diagnostic Ultrasound Safety

2014 ◽  
Vol 8 (2) ◽  
pp. 178-183 ◽  
Author(s):  
Kazuo Maeda
Keyword(s):  
Obstet Gynecol ◽  
Physical Property ◽  
Diagnostic Ultrasound ◽  
Mechanical Effect ◽  
Mechanical Index ◽  
Pulsed Doppler ◽  
Output Intensity ◽  
Thermal Index ◽  
4D Ultrasound ◽  
Pulsed Doppler Ultrasound

ABSTRACT Ultrasound bioeffect is discussed from its physical property, i.e. thermal effect by thermal index, mechanical effect by mechanical index, and by the output intensity of ultrasound. Generally, thermal and mechanical indices should be lower than 1 in obstetrical setting, and threshold output intensity of no bioeffect is lower than SPTA 240 mW/cm2 in pulse wave. Pulsed Doppler ultrasound thermal and mechanical indices should be also lower than 1, and should be carefully used it in 11 to 13+6 weeks of pregnancy. Real-time B-mode, transvaginal scan, pulsed Doppler, 3D and 4D ultrasound were separately discussed in the ultrasound safety. Generally diagnostic ultrasound is safe for the fetus and embryo, if thermal and mechanical indices are lower than 1, and ultrasound devices are safe, if it is used under official limitation, e.g. the output intensity is less than SPTA 10 mW/cm2 in Japan. The ultrasound user is responsible ultrasound safety, e.g. higher thermal and mechanical indices than 1 should be lowered to be lower than 1, controlling the device output intensity. The user should learn bioeffects of ultrasound and prudent use of ultrasound under the ALARA principle. How to cite this article Maeda K, Kurjak A. Diagnostic Ultrasound Safety. Donald School J Ultrasound Obstet Gynecol 2014;8(2):178-183.

scholarly journals Quantitative 3D imaging of partially saturated granular materials under uniaxial compression

2021 ◽  
Author(s):  
Marius Milatz ◽  
Nicole Hüsener ◽  
Edward Andò ◽  
Gioacchino Viggiani ◽  
Jürgen Grabe
Keyword(s):  
Granular Materials ◽  
Uniaxial Compression ◽  
Water Clusters ◽  
Local Strain ◽  
Confining Pressure ◽  
Mechanical Effect ◽  
Compression Tests ◽  
Initial Water ◽  
Interfacial Areas ◽  
Membrane Effects

AbstractGauging the mechanical effect of partial saturation in granular materials is experimentally challenging due to the very low suctions resulting from large pores. To this end, a uniaxial (zero radial stress) compression test may be preferable to a triaxial one where confining pressure and membrane effects may erase the contribution of this small suction; however, volume changes are challenging to measure. This work resolves this limitation by using X-ray imaging during in situ uniaxial compression tests on Hamburg Sand and glass beads at three different initial water contents, allowing a suction-dependent dilation to be brought to the light. The acquired tomography volumes also allow the development of air–water and solid–water interfacial areas, water clusters and local strain fields to be measured at the grain scale. These measurements are used to characterise pertinent micro-scale quantities during shearing and to relate them to the measured macroscopic response. The new and well-controlled data acquired during this experimental campaign are hopefully a useful contribution to the modelling efforts—to this end they are shared with the community.

scholarly journals The interaction between two trains of impulses converging on the same motoneurone

1929 ◽  
Vol 105 (738) ◽  
pp. 363-371 ◽  
Keyword(s):  
Mechanical Effect ◽  
The Other ◽  
Muscle Fibres ◽  
Flexor Muscle ◽  
Afferent Pathways ◽  
Afferent Nerves ◽  
Maximal Stimulation ◽  
The Common ◽  
The Relationship ◽  
Stimulation Of

It was shown in an earlier paper (7) that if maximal stimulation of either of two different afferent nerves can reflexly excite fractions of a given flexor muscle, there are generally, within the aggregate of neurones which innervate that muscle, motoneurones which can be caused to discharge by either afferent (i. e., motoneurones common to both fractions). The relationship which two such afferents bear to a common motoneurone was shown, by the isometric method of recording contraction, to be such that the activation of one afferent, at a speed sufficient to cause a maximal motor tetanus when trans­mitted to the muscle fibres, caused exclusion of any added mechanical effect when the other afferent was excited concurrently. This default in mechanical effect was called “occlusion.” Occlusion may conceivably be due to total exclusion of the effect of one afferent pathway on the common motoneurone by the activity of the other; but facilitation of the effect of one path by the activation of the other when the stimuli were minimal suggests that, in some circumstances at least, the effect of each could augment and summate with th at of the other at the place of convergence of two afferent pathways. Further investigation, using the action currents of the muscle as indication of the nerve impulses discharged by the motoneurone units, has now given some information regarding the effect of impulses arriving at the locus of convergence by one afferent path when the unit common to both is already discharging in response to impulses arriving by the other afferent path. Our method has been to excite both afferent nerves in overlapping sequence by series of break shocks at a rapid rate and to examine the action currents of the resulting reflex for evidence of the appearance of the rhythm of the second series in the discharge caused by the first when the two series are both reaching the motoneurone.

scholarly journals Predicting the Number of Parties: A Quantitative Model of Duverger's Mechanical Effect

1993 ◽  
Vol 87 (2) ◽  
pp. 455-464 ◽  
Author(s):  
Rein Taagepera ◽  
Matthew Soberg Shugart
Keyword(s):  
National Level ◽  
Quantitative Model ◽  
Mechanical Effect ◽  
Structural Constraints ◽  
Effective Number ◽  
Institutional Variables ◽  
National Assembly ◽  
Effective Number Of Parties ◽  
Number Of Parties ◽  
Great Portion

The mechanical effect of electoral systems, identified by Maurice Duverger, can be estimated by means of a quantitative model. The model predicts the range within which the effective number of parties in a district should fall for a given magnitude (number of seats) of the district. At the national level, a related model predicts the effective number of parties based on the effective magnitude and the number of seats in the national assembly. The institutional variables considered—magnitude and assembly size—define a great portion of the structural constraints within which a given country's politics must take place. The model developed provides a good fit to data in spite of its having been developed from outrageously simple starting assumptions.

Memoirs: On the Anatomy of Cerearia Macrocerca from Spliaerium Corneum

1940 ◽  
Vol s2-82 (326) ◽  
pp. 311-326
Author(s):  
G. G. VICKERS
Keyword(s):  
Mechanical Effect ◽  
Excretory Vesicle ◽  
Large Numbers ◽  
Sphaerium Corneum ◽  
Gill Lamellae

A detailed anatomical description is given of the sporocyst and cercaria of Cercaria macrocerca (Fil.) from the gills of Sphaerium corneum (Linn.). The development of the large cells surrounding the excretory vesicle of the cercaria is described. It has been found that the granules with which these cells are packed originate round the nucleus and afterwards migrate towards the lumen of the vesicle. These granules do not appear to be discharged on encystment of the cercaria to act as cystogenous material; they are shed gradually into the excretory vesicle, and it is therefore natural to suppose that they are granules of excretory material. In heavy infestations the mechanical effect of large numbers of sporocysts between the gill lamellae of the host completely prevents reproduction of the mollusc. Cercariae escaping from the sporocysts continually rupture the gill lamellae of the host, and large areas of the gills are thus put out of action.

Obesity and its effects on the esophageal mucosal barrier

2021 ◽  
Vol 321 (3) ◽  
pp. G335-G343
Author(s):  
Shere Paris ◽  
Rebecca Ekeanyanwu ◽  
Yuwei Jiang ◽  
Daniel Davis ◽  
Stuart Jon Spechler ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Gastroesophageal Reflux ◽  
Visceral Adipose Tissue ◽  
Esophagogastric Junction ◽  
Mechanical Effect ◽  
Mucosal Barrier ◽  
Abdominal Pressure ◽  
Esophageal Mucosa ◽  
Barrier Integrity ◽  
Visceral Adipose

Obesity is associated with gastroesophageal reflux disease (GERD) and its complications including reflux esophagitis, Barrett’s esophagus, and esophageal adenocarcinoma. Traditionally, these associations have been attributed to the mechanical effect of abdominal fat in increasing intra-abdominal pressure, thereby promoting gastroesophageal reflux and causing disruption of antireflux mechanisms at the esophagogastric junction. However, recent studies suggest that visceral adipose tissue (VAT) produces numerous cytokines that can cause esophageal inflammation and impair esophageal mucosal barrier integrity through reflux-independent mechanisms that render the esophageal mucosa especially susceptible to GERD-induced injury. In this report, we review mechanisms of esophageal mucosal defense, the genesis and remodeling of visceral adipose tissue during obesity, and the potential role of substances produced by VAT, especially the VAT that encircles the esophagogastric junction, in the impairment of esophageal mucosal barrier integrity that leads to the development of GERD complications.

Ventilatory Muscle Activity in Intact Preparations of Aeshnid Dragonfly Larvae

1972 ◽  
Vol 56 (2) ◽  
pp. 527-536
Author(s):  
R. S. PICKARD ◽  
P. J. MILL
Keyword(s):  
Muscle Activity ◽  
Mechanical Effect ◽  
Critical Position ◽  
Normal Ventilation

1. The expiratory role of the segmental, respiratory dorso-ventral muscles, and the inspiratory role of the subintestinal muscle, have been confirmed using intact preparations of aeshnid dragonfly larvae. 2. The strain developed by individual respiratory dorso-ventral muscles has been measured. 3. The respiratory dorso-ventral muscles all cease firing simultaneously, about 100 msec before the sterna are fully raised, and do not have any mechanical effect on the sterna after this time. It is suggested that the delay is caused either because the role of these muscles is to lift the sterna past some critical position, and/or because of the inertia of the expiratory current. 4. Periodically the sterna are raised and then lowered slowly in a series of steps, each pause in the lowering coinciding with activity in the respiratory dorso-ventral muscles. This form of ventilation is compared with others previously described. 5. In normal ventilation, and in other types of ventilation, activity in the respiratory dorso-ventral muscles shows a pronounced tendency to begin in the most posterior segments and to continue for longer periods in those segments. 6. Some aspects of the central neural connexions involved in normal ventilation are discussed.

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