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The hypersonic sound velocity of SiO2 glass has been measured to 57.5 GPa at room temperature by Brillouin scattering in diamond cells. On compression both longitudinal and transverse modes exhibit an anomalous change in slope in the low‐pressure region. Between 12 GPa and 23 GPa, the bulk sound velocity increases significantly and then follows a trend similar to that expected for coesite. The pressure‐density relation calculated from the measured sound velocities within the elastic compression region is in good agreement with several previous measurements.

In this chapter: the regimes of mechanical response; nonlinear elastic compression; stress tensors; the Hugoniot elastic limit; elastic-plastic deformation; hydrodynamic flow; phase transformation; release waves; other mechanical aspects of shock propagation; first-order and second-order behaviors.

Source Citation Sachdeva A, Dalton M, Amaragiri SV, Lees T. Elastic compression stockings for prevention of deep vein thrombosis. Cochrane Database Syst Rev. 2010;(7):CD001484. 20614425

Prandoni P, Lensing AW, Prins MH, et al . Below-knee elastic compression stockings to prevent the post-thrombotic syndrome: a randomized, controlled trial. Ann Intern Med 2004;141:249–56. [OpenUrl][1][CrossRef][2][PubMed][3][Web of Science][4] Q In patients with a first episode of acute symptomatic proximal deep venous thrombosis (DVT), do below knee elastic compression stockings prevent the post-thrombotic syndrome (PTS)? Clinical impact ratings GP/FP/Primary care★★★★★★☆ IM/Ambulatory care ★★★★★★☆ Internal medicine ★★★★★★☆ Haematology ★★★★★☆☆ ### ![Graphic][5] Design: randomised controlled trial. ### ![Graphic][6] Allocation: {concealed*}†. ### ![Graphic][7] Blinding: blinded {data collectors, outcome assessors, and monitoring committee}†.* ### ![Graphic][8] Follow up period: mean 49 months (range 6–60 mo). ### ![Graphic][9] Setting: university hospital in Padua, Italy. ### ![Graphic][10] Patients: 180 patients (mean age 62 y, 57% women) with a first episode of acute symptomatic proximal DVT (confirmed by ultrasonography) who were receiving conventional anticoagulant treatment. Exclusion criteria were recurrent ipsilateral DVT, pre-existing leg ulcers or signs of chronic venous insufficiency, bilateral thrombosis, a short life expectancy, or contraindication for use of stockings. ### ![Graphic][11] Interventions: daily wearing of below knee, graded, elastic compression stockings … [1]: {openurl}?query=rft.jtitle%253DAnnals%2Bof%2BInternal%2BMedicine%26rft.stitle%253DANN%2BINTERN%2BMED%26rft.issn%253D0003-4819%26rft.aulast%253DPrandoni%26rft.auinit1%253DP.%26rft.volume%253D141%26rft.issue%253D4%26rft.spage%253D249%26rft.epage%253D256%26rft.atitle%253DBelow-Knee%2BElastic%2BCompression%2BStockings%2BTo%2BPrevent%2Bthe%2BPost-Thrombotic%2BSyndrome%253A%2BA%2BRandomized%252C%2BControlled%2BTrial%26rft_id%253Dinfo%253Adoi%252F10.7326%252F0003-4819-141-4-200408170-00004%26rft_id%253Dinfo%253Apmid%252F15313740%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [2]: /lookup/external-ref?access_num=10.7326/0003-4819-141-4-200408170-00004&link_type=DOI [3]: /lookup/external-ref?access_num=15313740&link_type=MED&atom=%2Febmed%2F10%2F1%2F22.atom [4]: /lookup/external-ref?access_num=000223290900001&link_type=ISI [5]: /embed/inline-graphic-1.gif [6]: /embed/inline-graphic-2.gif [7]: /embed/inline-graphic-3.gif [8]: /embed/inline-graphic-4.gif [9]: /embed/inline-graphic-5.gif [10]: /embed/inline-graphic-6.gif [11]: /embed/inline-graphic-7.gif

What is a clinician to do to prevent long-term complications of acute symptomatic deep venous thrombosis? Should all patients routinely use elastic compression stockings over the long term, or can ...

Symptomless deep venous thrombosis might occur in up to 10% of long haul airline travellers, concluded the authors of a new study published last week, which assessed the overall frequency of the condition in long haul airline passengers ( Lancet 2001;357:1485). John Scurr, consultant surgeon from the Royal Free and University College Medical School, London, and colleagues, recruited 89 male and 142 female passengers aged over 50. They randomly allocated half to wear knee high elastic compression stockings and half to wear normal travel clothes. The passengers, who all took flights of at least eight hours and returned …

In Reply. —The literature on prevention of venous thromboembolism following total hip replacement is highly controversial. The overall tone of Dr Megerman's comments reflects the controversy and uncertainty in this area and highlights the need for meta-analysis. We were aware of the different mechanisms of action between intermittent pneumatic compression and static elastic compression. Megerman erroneously assumes, however, that different mechanisms of action translate into different efficacies. We combined these mechanical modalities because of separate crude risks that were no different clinically or statistically. This preliminary analysis consisted of simple tabulation of numerators and denominators for each modality and was determined separately from our more detailed analysis. We carefully considered how to include the few treatment arms that combined pharmacologic and mechanical modalities. As stated in the article, our assignment of these combination groups to the pharmacologic arm was arbitrary but made more clinical sense than assignment to the mechanical

To the Editor. —In their recent article on venous thromboembolism after total hip surgery, Drs Imperiale and Speroff 1 present a sophisticated meta-analysis of deep venous thrombosis and pulmonary embolism (PE) rates obtained with different prophylactic options. Unfortunately, their treatment of mechanical prophylaxis is naive. They seem to be unaware that intermittent pneumatic compression (using sleeves) and static elastic compression (using stockings) are separate modalities, with different mechanisms of prophylactic action and, thus, different efficacies in preventing deep venous thrombosis or PE when used individually or in combination. And while they do distinguish stockings from pharmacologic agents when these are used separately, they arbitrarily assign patients who used stockings in combination with drugs to the group that used drugs alone. Would the results described for the low-molecular-weight heparin (LMWH) group, for example, be as good if it hadn't included patients who used graded compression stockings? The authors' failure to allow

Experimental data are presented for shock propagation along the 〈111〉 crystallographic direction in single−crystal LiF. Within experimenal bounds, an elastic response to 30 kbar is observed. This is in marked contrast with identical 〈100〉 crystals and earlier studies on other single crystals. The elastic behavior along the 〈111〉 direction is in good agreement with low stress and strain rate studies but raises interesting questions regarding crystal strength and dislocation mechansim operative under shock loading.

Various crystal forms of sulphathiazole, barbitone and aspirin were compressed in a single-punch tablet machine instrumented to monitor axially applied and radially transmitted forces, and upper punch movement. The changes in radial stress during the compression cycle depended upon the polymorphic form of the compressed material. The results were rationalized in terms of the degree of plastic flow/crushing that occurred with each material, and the degree to which the final compact underwent elastic compression. It is postulated that the reduction in the transition temperature of polymorphic forms of sulphathiazole and barbitone and the polymorphic transition of sulphathiazole Form II was due to the production of dislocations in the crystal and the distortion of the crystals at crystal boundaries formed in the compressed materials.

The value of elastic compression and defibrotide, a profibrinolytic and antithrombotic drug, in patients with venous hypertension, lipodermatosclerosis and ulceration was assessed in a cross-over trial. Elastic compression alone and in association with defibrotide (800 mg/day) were completed the study (18 were treated with the combined treatment in the first 3 months and 14 in the second period). We evaluated the decrease of the areas of liposclerosis and ulceration by computerized analysis of the areas. We also studied the decrease of leg circumference and subjective clinical improvement by an analogue scale line. Patients were also evaluated by laser-Doppler flowimetry, transcutaneous PO2 and PCO2 measurements, capillary permeability and fibrinolytic activity. Both forms of treatment were active in reducing the areas of liposclerosis and ulceration but combined treatment with defibrotide and elastic compression was significantly more effective in reducing both liposclerosis and ulceration, and in improving microcirculatory parameters and capillary permeability. The improvement in objective evaluation was comparable to the clinical improvement measured by the analogue score. The positive variation of all parameters studied was associated with a significant increase of fibrinolytic activity during the administration of defibrotide. No side effects were observed during this study. These results suggest that defibrotide treatment is effective in treating liposclerosis and ulceration in postphlebitic limbs with venous hypertension, improving both microcirculatory parameters and subjective symptoms.

Summary The physiological effects of elastic compression stockings on venous disorders of the leg have been studied in three groups of 10 patients. These patients were divided by examination and ascending venography into those with: (a) a normal venous system in the leg, (b) superficial varicose veins and (c) a post-phlebitic limb. In a randomized cross-over trial each group wore Eesiness NHS two-way stretch or Sigvaris medium compression below-knee stockings for three weeks. In the post-phlebitic limb group a further comparison was made with Sigvaris strong compression below-knee stockings after a 6-week rest period. The effects were objectively compared using foot volumetry and sodium (24Na) subcutaneous tissue clearance. The physiological benefits of Sigvaris medium and strong compression stockings were comprehensively demonstrated by both methods of assessment in patients with the post-phlebitic limb. Benefit from Sigvaris medium compression stockings was also demonstrated in the patients with varicose veins. In the group with normal veins there were negligible physiological benefits from compression stockings. Eesiness stockings failed to produce a significant physiological effect in each group.

A compaction theory for saturated sand, of differential type, is applied to shear wave propagation through a layer induced by cyclic horizontal acceleration of its base. The compaction relation incorporates dependence on the pore fluid pressure, and in turn the pore pressure is related to the compaction through the elastic compression relations. An assumption of undrained flow, which will yield the maximum pore pressures, allows straightforward numerical solution of the simplified dynamic equations. A variety of results are computed for comparison with alternative predictions.

1. The damping factor b depends on the elastic properties of the soil base and the dimensions of the lower surface of the foundation. Hence, one of the values — the coefficient of uniform elastic compression Cz — makes it possible to find both the elastic and damping characteristics of the soil base. To evaluate the damping characteristics, it is expedient to use the specific damping factor introduced in this article.

The redistribution of boron in silicon under the action of elastic stress fields created by the diffusion of various impurities is investigated experimentally. It is shown that the diffusion of boron slows down in the elastic compression interval. The slowing effect intensifies with increasing absolute stress values. A model is proposed to account qualitatively for the experimental results.

The strength and elasticity of layers of polyurethane foam with cylindrical cavities have been investigated on the interval of variation of the specific weight of the foam from ρ0 = 0.2 to ρ0 = 0.7 gf/cm3. A correlation has been established between the proportionality limit in compression along the channel axes and the modulus of elasticity of a cylindrical tube of foam with a radially restrained outer surface taken as a model of a layer with cylindrical cavities. The experimental results are compared with the theory of elastic compression of tubes with free and restrained ends.

A low oxygen tension might contribute to the dermatological changes produced by deep venous insufficiency and venous stasis. Since elastic support is often prescribed for stasis disorders, it would be of value to know whether compression alters the oxygen tension in affected skin. We performed studies in which the transcutaneous Po2 (TcPo2) was determined for the foot or lower leg in subjects with normal veins (n = 9) or with dermatitis caused by documented deep venous insufficiency (n = 14). Measurements were made using O2-sensing electrodes placed 1–2 cm apart; surface temperature was 45°C for one electrode (producing maximal vasodilation of the underlying skin) and 42°C for the other (producing submaximal vasodilation). The vasodilation index (VI = TcPo2 at 42 °C/TcPo2 at 45°C) was used as an index of vasomotor tone. In normal limbs, TcPo2 (mmHg) and VI were affected by the subject's posture (TcPo2 = 38.8 at 42°C and 61.4 at 45°C when supine; 40.8 at 42°C and 74.6 at 45°C when upright with legs dependent; VI = 0.63 supine and 0.53 upright). In limbs with venous stasis, TcPo2 and VI were considerably lower (TcPo2 = 23.6 at 42°C and 51.5 at 45°C when supine; 20.8 at 42°C and 60.5 at 45°C when upright; VI = 0.48 supine and 0.37 upright). Following the application of an elastic wrap to the limbs with stasis, upright values for TcPo2 and VI were substantially improved (TcPo2 with compression = 28.8 at 42°C and 62.4 at 45°C; VI = 0.46). We conclude that (1) TcPo2 is reduced in regions of skin affected by stasis dermatitis, and (2) elastic compression improves TcPo2 (during upright posture) in limbs with stasis dermatitis.

A comprehensive study of the molecular orientation and crystalline texture (the latter by low-angle x-ray diffraction supplemented by swelling measurements) in doubly oriented polyethylene on consecutive stages of heat annealing has allowed a picture of the structure and reorientation processes to be outlined. Thus even a drawn and rolled branched polyethylene is found to contain lamellae having {h0l}s basal planes with obliquities of 35–45°, in close analogy to those found in crystals grown from dilute solution and extracted from unoriented bulk linear polyethylenes. The initial ranges of the relaxation can be described by consecutive interlamellar and intralamellar slips activated by a rubber elastic compression. The cohesion between the lamellae opposing this is also found to be partially rubber elastic, and it is demonstrated that the resultant of the two elastic forces can be shifted by physical and chemical means. The individuality of the lamellae—requiring an appreciable amount of chain folding—is borne out. The possibility of producing macroscopic single-crystal analogs is also demonstrated.

An analytical model for tissue behavior under pressure in proposed. The model consists of an arrangement of springs and dashpots. Such models are, of course, well known, but do not appear to have been proposed previously for skin tissue. The model relates the viscoelastic properties of the skin tissue to quantities that can be measured in vivo , such as instantaneous elastic compression, delayed elastic recovery, and molding deformation. So if some in vivo measurements can be carried out to measure these quantities, this model can be used to determine the viscoelastic properties of skin tissue. The model is checked for normal conditions, as well as conditions of lymphatic disease or disability, and compared with clinical measurements.

A Test of Isostasy The theory of isostasy is widely favored as an explanation of recent uplifts in the glaciated tracts of North America and Europe. If the earth’s crust sinks after a heavy, extensive load of ice is put on it, and rises after that ice melts; if the crust so behaves each time that one and the same region is glaciated and deglaciated; if similar behavior were proved in separate areas—eastern Canada, the British Isles, Scandinavia, British Columbia, Patagonia, and Antarctica—the theory would almost become certainty. As a matter of fact, field studies have been largely confined to but three of the greater ice-cap areas and in each case to uplift following the latest deglaciation. Complete testing of the isostatic theory after the manner described is evidently much more difficult than the partial test so far applied. The sinking under load is in small part due. to purely elastic compression, . . .

Synopsis The Paper reviews 25 years of Norwegian experience in the use of steel piles for foundations. The condition of soft clay overlying a hard and oftensteeply inclined rock surface which is common in Norway creates a number of problems in the design and driving of point bearing piles to bedrock. Methods of pile driving which have been evolved to ensure a satisfactory sealing of the pile point into rock are described in detail. The problems of the buckling of piles under load and of the corrosion of steel piles in the ground are discussed in the light of recorded experience. Finally, the settlements of single piles and of buildings are discussed.The settlement of a successful single pile is found approximately equal to the elastic compression of the pile, whereas observations indicate that thesettlements of buildings are two to four times this value. L'article passe en revue 25 ans d'expérience norvégienne dans I'emploi de pieux en acier pour fondations. Les conditions souvent rencontrées en Norvège, de l'argile recouvrant une surface rocheuse dure et souvent fortement inclinée, créent un certain nombre de problèmes dans I'exécution du dessin et l'enfoncement des pieux à pointes dans un sons-sol rocheux. Des méthodes d'enfoncement de pieux qui ont été développées pour assurer un scellement satisfaisant de la pointe de pieux dans le rocher, sont déccrites détail. Les problèmes du flambage des pieux sons pression et de la corrosion des pieux en acier dans le sol sont discutés an jour des expériences enrégistrées. Enfin, les tassements de pieux individuels et de bâtiments sont discutés. On remarque que le tassement d'un pieu individuel bien réussi est approximativement égal à la compression élastique du pieu, tandis que les observations indiquent que les tassements de bâtiments sont de deux à quatre fois cette valeur.

IntroductionElastic compression stockings exerting a progressive pressure, higher at the calf than at the ankle (progressive elastic compression stockings, PECS), have already proved to be more comfortable, easier to put on and more effective in improving venous pumping function compared to graduated compression elastic stockings (GECS). Nevertheless, PECS could have a negative effect on the prevention and treatment of oedema or even favour oedema formation.The aim of the present study was to investigate if, in normal volunteers, PECS are able to prevent leg swelling during their working shift.MethodsA total of 30 normal volunteers (14 males, 16 females aged 36.4 ± 6.6 years) staying standing or sitting during their shift were enrolled into the study. Their leg volume was measured at the beginning and at the end of their working shift on 2 consecutive days. On one day, the volunteers did not put on any stockings; on the other day, they wore GECS on one leg and PECS on the other. The difference between the leg volume measured at the end of the shift and the basal volume in the morning was called ‘occupational oedema’.Interface pressure at points B1 and C was measured immediately after stockings' application and before removal. The volunteers were asked to report about difficulty of putting on the stockings and comfort during wearing time. The results were submitted to statistical analysis.ResultsThe GECS and PECS groups had similar baseline leg volumes (3143 vs. 3154 ml) and occupational oedema (134 vs. 137.5 ml); after putting on the stockings, occupational oedema was reduced in both legs but the reduction was significantly greater with PECS (20 vs. 40 ml with GECS) (P

The increased widespread use of explosion welding calls for a detailed investigation of the metal in the near-weld zone. During impact a considerable amount of the explosion energy is released in the form of heat. Within the metal 80-90% of the thermal energy is associated with the conversion to heat of the energy of plastic deformation, only 10-20% being released as a result of the elastic compression of the metal during passage of the shock waves [1]. At the interface a certain additional amount of heat is released as a result of surface friction; this leads to the melting and welding of the metals.

The possibilities and the advantages of synchrotron radiation for X-ray diffractometric studies on deformation of crystalline materials in shock compression are discussed. A device, designed and manufactured for studying the deformation in local compression, is described. Its time resolution achieves 10 −3 s and the spatial resolution is 10 −5 m. The experimental data on elastic compression of a LiF crystal at local impulse shock are presented.

1. Experimental data have been obtained on angle parameters and forward slip in the rolling of nonporous strips from aluminum powder and aluminum and aluminum alloy granules. 2. The elastic compression experienced by the rolls decreases the degree of reduction of the strip in the forward slip zone, as a result of which the true forward slip is much less than that calculated with Golovin-Dresden's formula.

An analysis is carried out of the elastic compression of rolls during the rolling of metal powders, and a description is given of methods of its determination. The relationship between the angle of elastic roll compression and maximum pressure has been established for copper, iron, and nickel powders.

Thermo-elasticity is the phenomenon that heat is produced, (or in some materials “lost”), when a body undergoes elastic compression, and vice- versa when it undergoes extension. The effect has been appreciated since the time of Kelvin, and, in the past few decades various workers, (e.g., [1], [2]) have studied it for the purpose of applying it for experimental stress analysis. The work of Belgen [2] is particularly substantial and relevant and Biot [3] gives a thermodynamic analysis.

In patients undergoing surgical operations, there is a profound fall in the velocity of venous return during the induction of anesthesia. This may be the point at which thrombosis commences in the veins of the leg. The wearing of a tubular elastic compression bandage on the legs prevents this fall. It also reduces the clinical incidence of postoperative deep venous thrombosis [10].

Measurements of the temperature rise occuring on compression, recompression and relaxation of compacts formed from Asagran, sodium chloride and boric acid have been made by means of thermocouples inserted into the compressed materials. There are marked differences in temperature rise for the different compacts when compressed to a final force of 50 kN (5 tons). With all compacts there was a rise in temperature on initial compression and a fall in temperature on relaxation. The rise could be separated into two components—that due to compact formation plus a further rise due to its elastic compression. The fall in temperature is thought to result on release of the strain energy stored in the compact. The rise in temperature on recompression followed by the fall of relaxation could be repeated many times on the same compact. Both rise and fall were directly proportional to the final compression force used. The fall on relaxation appeared to be numerically less than the rise on recompression for compacts of boric acid and Asagran. Lubrication of Asagran with magnesium stearate had little effect on the temperature rises.

Background. The beneficial effects of graduated elastic compression stockings (GCSs) have been demonstrated. However, their pressure performances are variable and unstable in practical applications owing to many influencing factors. Comprehensive assessment of skin pressure profiles may help elucidate the mechanisms of action of compression stockings. Objective. The objective of this study was to quantify and objectively evaluate the magnitude and distribution of skin pressure applied by different GCSs and to analyze the possible reasons influencing the stocking pressure performances. Methods. Six healthy females were required to wear eight kinds of GCSs with different pressure levels while standing upright. The skin pressures of 16 different positions located in four heights and four directions of the lower limb were measured and recorded by FlexiForce interface pressure sensors (Tekscan, Inc., Boston, MA, USA) and a multichannel measuring system. Results. The pressure gradients, pressure levels, and testing locations significantly influenced skin pressure (p < .001). All tested GCSs exerted the highest pressure at the ankle region, and the pressure gradually decreased toward the thigh, which follows the gradient design of GCSs. However, many of them failed to produce the perfect pressure gradients from the ankle region to the calf region. Obviously, reversed pressure gradients occurred in the medial side of the leg, where the pressure at the ankle region was lower than that on the prominent part of the calf by 36% on average. GCSs with higher pressure levels applied higher skin pressure on the lower limb. The pressure at the anterior side was far higher than that in the medial and lateral directions. The distribution patterns of skin pressure at transverse sections were similar to the anatomic outlines of cross sections of the leg. The measured average ankle pressure of all tested GCSs did not reach the pressures specified by the manufacturers. Conclusion. Skin pressure distributions and magnitudes applied by GCSs were significantly influenced by the locations of testing points in terms of height and direction, which are determined by the specific anatomic structure and body shape of individual human legs and potentially influenced by the pressure sensor and testing methods.

IN the course of investigations into the mechanical properties of natural and synthetic rubber intended for use in anti-vibration devices, variations of a large order were encountered. As these variations seemed largely dependent upon temperature, a preliminary detailed examination in the region of 5–40° C. has been made. Using a mechanical vibrator somewhat similar to that employed by Gehman1 and working at 20–60 c.p.s., measurements of dynamic elastic compression modulus and associated resilience were made by the well-known resonance method. A detailed description of the apparatus, method and results is to be published later; for the present it may be said that the test pieces were in the form of cylindrical rubber blocks in. in diameter and in. high, bonded at each end to steel screws by the conventional brass-plate method.

In the course of investigations into the mechanical properties of natural and synthetic rubbers intended for use in antivibration devices, variations of a large order were encountered. As these variations seemed to be largely dependent on temperature, a preliminary detailed examination in the region of 5° to 40° C was made. With the aid of a mechanical vibrator somewhat similar to that employed by Gehman, and working at 20–60 c.p.s., measurements of dynamic elastic compression modulus and associated resilience were made by the well known resonance method. A detailed description of the apparatus, method, and results is to be published later; for the present time, it may be said that the test-pieces were in the form of cylindrical rubber blocks, 0.875 inch in diameter and 0.875 inch high, bonded at each end to steel screws by the conventional brass-plate method.