Greater Strain Research Articles

Research Study on Neck Injury Lessening with Active Head Restraint Using Human Body FE Model

Objectives: The objective of this study is to examine the effectiveness of the active head restraint system in reducing neck injury risk of car occupants in low-speed rear impacts. Methods: A human body FE model “THUMS” was used to simulate head and neck kinematics of the occupant and to evaluate loading to the neck. Joint capsule strain was calculated to predict neck injury risk as well as NIC. The validity of the model was confirmed comparing its mechanical responses to those in human subjects in the literatures. Seat FE models were also prepared representing one with a fixed head restraint and the other one with an active head restraint system. The active head restraint system was designed to move the head restraint forward and upward when the lower unit was lower unit was loaded by the pelvis. Rear impact simulations were performed assuming a triangular acceleration pulse at a delta-V of 25 km/h. Results : The model reproduced similar head and neck motions to those measured in the human volunteer test, except for active muscular responses. The calculated joint capsule strain also showed a good match with those of PMHS tests in the literature. A rear-impact simulation was conducted using the model with the fixed head restraint. The result revealed that NIC was strongly correlated with the relative acceleration between the head and the torso and that its maximum peak appeared when the head contacted the head restraint. It was also found that joint capsule strain grew in later timing synchronizing with the relative displacement. Another simulation with the active head restraint system showed that both NIC and joint capsule strain were lowered owing to the forward and upward motion of the head restraint. A close investigation of the vertebral motion indicated that the active head restraint reduced the magnitude of shear deformation in the facet joint, which contributed to the strain growth in the fixed head restraint case. Conclusions: Rear-impact simulations were conducted using a human body FE model, THUMS, representing an average-size male occupant. The cervical system including the facet joint capsules was incorporated to the model. The validity of the model was examined comparing its mechanical responses to those in the literature such as the whole body motion of the volunteer subject and the vertebral motion in the PMHS tests. Rear-impact simulations were conducted using the validated THUMS model and two prototype seat models; one had a fixed head restraint and the other one was equipped with an active head restraint system. The active head restraint system works moving the head restraint forward and upward when the lower unit is loaded by the pelvis. The head and neck kinematics and responses were analyzed from the simulation results. The force and acceleration rose at the pelvis first, followed by T1 and the head. The early timing of force rise and its magnitude indicated that the pelvis force was a good trigger for the active head restraint system. The results showed that the head was supported earlier in a case with the active head restraint system, and both NIC and joint capsule strain were lowered. The study also analyzed the mechanism of strain growth in the joint capsules. Relatively greater strain was observed in the direction of the facet joint surface, which was around 45 degrees inclined to the spinal column. The forward and upward motion of the active head restraint were aligned with the direction of the joint deformation and contributed to lower strain in the joint capsules. The results indicated that the active head restraint could help reduce the neck injury risk not only by supporting the head at an early timing but also through its trajectory stopping the joint deformation.

Transverse-Plane Mechanics at the Knee and Tibia in Runners With and Without a History of Achilles Tendonopathy

Retrospective cohort study. To determine if runners with a history of Achilles tendonopathy (AT) demonstrate a difference in transverse-plane motion and moments at the distal tibia and knee compared to runners without a history of AT. One of the more prevalent overuse running injuries is AT. It has been hypothesized that prolonged pronation causes contradictory rotational forces acting on the AT. Conflicting joint motions may also accentuate the rotation of the tendon. This may further affect the opposing transverse-plane moments at the knee and distal tibia. Eight runners with a history of AT and a noninjured control group consisting of 8 runners ran along a 20-m runway at a fixed speed. Biomechanical measurements were taken using a 6-camera motion analysis system and a force plate. Student t tests were employed to determine statistically significant differences (P </= .05) in transverse-plane motion and moment variables at the distal tibia and knee between groups. The AT group showed less tibial external rotation moment (P = .01) and peak knee internal rotation (P = .05) compared to the control group. There was no difference in external rotation moment at the knee (P = .34) or peak tibial internal rotation (P = .44). Runners with a previous history of AT exhibited less tibial external rotation moments during running. The lack of control in the transverse-plane at the distal tibia may be due to decreased function of the muscles primarily responsible for transverse-plane motion, resulting in greater strain on the AT in the transverse-plane. Designing an exercise program to strengthen lower leg muscles and improve distal tibial control in the transverse-plane may reduce the risk for developing AT or augment the rehabilitation of AT.

New directions for spectrum management

Changes in communications technology and markets have placed great strains on traditional approaches to spectrum regulation, which have had difficulty coping with the current rate of change in radiocommunications. New technologies including mobile telephony and wireless broadband posed challenges for governments who needed faster and more objective means of allocating spectrum to competing commercial interests. Spectrum regulators have turned increasingly to market-based and more flexible approaches to regulation, including auctions, pricing and trading. Challenges for the future include improving technology neutrality, improving the efficiency of use of government spectrum, and deciding how much spectrum to set aside for the spectrum commons.The views expressed in this article are the authors own and do not represent the views of ACMA. Copyright 2008 Geoff Luther. No part of this article may be reproduced by any means without the written consent of the publisher.

New directions for spectrum management: an international perspective

Changes in communications technology and markets have placed great strains on traditional approaches to spectrum regulation, which have had difficulty coping with the current rate of change in radiocommunications. New technologies including mobile telephony and wireless broadband posed challenges for governments who needed faster and more objective means of allocating spectrum to competing commercial interests. Spectrum regulators have turned increasingly to market-based and more flexible approaches to regulation, including auctions, pricing and trading. Challenges for the future include improving technology neutrality, improving the efficiency of use of government spectrum, and deciding how much spectrum to set aside for the spectrum commons.The views expressed in this article are the authors own and do not represent the views of ACMA. Copyright 2008 Geoff Luther. No part of this article may be reproduced by any means without the written consent of the publisher.

But, Words Can Never Hurt Me If … : Cultural Relativity in Evaluating Appraisals, Attributions, and Consequences of Hurtful Messages

The study explored the influence of self-construals, a well-investigated and important dimension of culture, on the process of feeling and responding to hurt. Participants responded to a survey measuring self-construals, overall hurt feelings, mood, attributions, and relational consequences. The findings revealed that interdependence was positively associated with hurt feelings, but found no support for the relationship between independence and hurt. Independence was associated with positive moods subsequent to receipt of a hurtful message, whereas greater negative moods were related to higher degrees of interdependence. Independence was related to greater potential for using assertive responses. Finally, higher degrees of interdependence were related to the perception of greater strain on the relationship. The results, taken as a whole, demonstrate that the way in which people experience hurtful messages is influenced, in part, by specific cultural values. As such, the way self is construed in relation to the environment must be taken into consideration in future theorizing on hurt in interpersonal relationships.

Poxvirus infection in Hungarian great tits ( Parus major ): Case report

From a total of 1819 great tits (Parus major) ringed in 2007 in Pilis Mountains, Hungary, 15 birds presented nodular proliferative lesions on different areas of the head and eyelids, suggesting a poxvirus infection. Three birds were submitted for analysis. The presence of avipoxvirus infection was confirmed by histopathology, electron microscopy (EM) and a polymerase chain reaction (PCR) based technique. Nucleotide sequence analysis of a 428 base pairs (bp) fragment of the viral 4b core protein gene revealed 100% identity between two of the Hungarian isolates (PM9 HUN, PM33 HUN) and two great tit poxvirus strains isolated in Norway in 1973 (GTV A256, GTV A311). The third Hungarian isolate (PM34 HUN) was more closely related to a different Norwegian isolate (GTVA310) than to the Hungarian isolates. The nucleotide sequence analysis of a shorter fragment of the viral 4b core protein (227 bp) gene revealed 100% identity between the Hungarian isolates, the same Norwegian isolates and a great tit poxvirus strain detected in Austria in 2007.

A Multipass ECAP Study of Modified Aluminium Alloys

ECAP (Equal Channel Angular Pressing) is a very interesting method for modifying microstructure in producing UFG (Ultra Fine Grained) materials. It consists of pressing test samples through a die containing two channels, equal in cross section and intersecting at an angle Φ. As a result of pressing, the sample theoretically deforms by simple shear and retains the same cross sectional area to repeat the pressing for several cycles. 2-D and 3-D FEM simulations of both one and four ECAP passes of two modified aluminium alloys were performed in order to investigate the deformation state of processed workpiece and, moreover, the effect of the different alloy related Strain Hardening Rate (SHR), die geometry (in terms of variation of channel outer angle) and friction on deformation distribution and magnitude. FEM results showed a lower equivalent plastic strain on the outer side of both cross and longitudinal sections of the billets after one and four passes. Microhardness tests performed on the same sections of ECAP processed billets supported these findings. Moreover, FEM analysis indicated that an higher SHR means a greater strain inhomogeneity on cross section of the processed billet. The same effect was observed by increasing the channel outer angle by computing friction.

Biomechanics of the Foot in Dance: A Literature Review

In any form of dance, great strain is placed on the lower extremity and the strong but sensitive foot. A large percentage of injuries to dancers involve the foot and ankle. Understanding the structure, biomechanics, and physics of the lower extremity helps to diagnose and evaluate the mechanics behind these injuries. The lower extremity function is complicated and needs to be studied carefully to understand its laws and principles. What often happens when injury occurs is that the dancer is not satisfying the natural requirements of movement through the joints. For example, her relevé is causing sickling and unstable foot positions because the forefoot is not strong enough and the leg external rotation and hip joint muscular support are not simultaneous with the heel raise. In the opposite direction, when the dancer is executing plié, the outcome of poor control of a weakened foot is strain on the passive supporting structures, such as the plantar ligaments, joint capsules, and plantar fascia. This leads to faulty bone alignment, increased bone load, and risk of overuse syndromes in various tissues.

Transatlantic Protestantism and American Independence

American independence in 1783 marked a clean break in constitutional relations with Britain. How other aspects of a complex pattern of transatlantic connections fared is less clear-cut: elements of continuity can be found as well as the effects of disruption. This paper is concerned with relations between the Protestant denominations in America and Britain. On the eve of the Revolution there are clear indications that, as in so many other aspects of Anglo-American life, British and American Protestant denominations were drawing closer to one another. The war put such connections under great strain. For some denominations, notably the Quakers and those British Rational Dissenters who had generally allied with revolutionary America, a return to something like the past was relatively easy. For Anglicans and Methodists, it was impossible and new and largely separate structures quickly evolved in the United States. The war also drove a wedge between many Scottish Presbyterians and members of the older English Dissenting bodies and their American counterparts, who after the peace increasingly asserted their autonomy. In time new patterns of transatlantic Protestant cooperation developed, often outside formal denominational structures. The disruptive effects of a long and bitter war on what had been close-knit Christian communities should not, however, be underestimated.

Computer science and decision theory

This paper reviews applications in computer science that decision theorists have addressed for years, discusses the requirements posed by these applications that place great strain on decision theory/social science methods, and explores applications in the social and decision sciences of newer decision-theoretic methods developed with computer science applications in mind. The paper deals with the relation between computer science and decision-theoretic methods of consensus, with the relation between computer science and game theory and decisions, and with “algorithmic decision theory.”

Study of ECAP Processing Routes on Semi-Solid Microstructure Evolution of A356 Alloy

Semi- solid (SS) processing technologies provide the production of metal parts with homogeneous, fine and globular – grained microstructure. This is one of the most successful and reliable methods to produce near net shape products exhibiting good mechanical properties. Production of feed stock with non-dendritic and spherical structure is the critical factors in semisolid forming. Among several processes to obtain a globular microstructure, the SIMA (strain induced melt activated) process is simple and advantageous with respect to equipment and eliminating the melting stage before reheating. In this research, Al (A356) has been used and in order to induce strain, ECAP (equal channel angular pressing) method has been applied. ECAP is a method in which a great strain is induced and severe plastic deformation without any changes in cross section area occurs. To induce larger strain, ECAP process was carried out on annealed specimens up to several passes in route A (no rotation of samples around linear axis between each pass) and Bc (90◦ rotation of samples around linear axis between each pass), in ambient temperature. The reheating condition was optimized and the comparison between different routes and number of passes was investigated. The microstructure evolution of deformed and reheated Al (A356) was characterized by SEM (Scanning electron microscopy) and optical microscopy. In addition, the relation between the induced strain with size and shape of particles has been studied.

Microstructure and mechanical properties in an AZ31 magnesium alloy sheet fabricated by asymmetric hot extrusion

Hot extrusion is one of the effective methods to decrease grain size of materials. As grains are finer, the mechanical properties of materials can be improved. It was found that the grains of magnesium alloy AZ31 sheets could be reduced to 3 μm by a differential speed rolling at an elevated temperature. In the present study, one-pass asymmetric hot extrusion performed at temperature of 673 K was applied to fabricate an AZ31 magnesium alloy sheet in order to introduce great shear strain during the primary processing. The textures, microstructures and mechanical properties at room temperature along the extrusion planes from top surface to bottom surface were examined. The experimental results showed that the asymmetric hot extrusion effectively weakened the basal texture and improve the ductility at room temperature.

Comparison of Saccharomyces cerevisiae strains of clinical and nonclinical origin by molecular typing and determination of putative virulence traits

Saccharomyces cerevisiae strains of clinical and nonclinical origin were compared by pulse field gel electrophoresis. Complete separation between strains of clinical origin and food strains by their chromosome length polymorphism was not obtained even though there was a tendency for the clinical and food strains to cluster separately. All the investigated strains, except for one food strain, were able to grow at temperatures ≥37 °C but not at 42 °C. Great strain variations were observed in pseudohyphal growth and invasiveness, but the characters were not linked to strains of clinical origin. The adhesion capacities of the yeast strains to a human intestinal epithelial cell line (Caco-2) in response to different nutritional availabilities were determined, as were the effects of the strains on the transepithelial electrical resistance (TER) across polarized monolayers of Caco-2 cells. The yeast strains displayed very low adhesion capacities to Caco-2 cells (0.6–6.2%), and no significant difference was observed between the strains of clinical and nonclinical origin. Both S. cerevisiae strains of clinical and non-clinical origin increased the TER of polarized monolayers of Caco-2 cells. Based on the results obtained in this study, no specific virulence factor was found that clearly separated the strains of clinical origin from the strains of nonclinical origin. On the contrary, all investigated strains of S. cerevisiae were found to strengthen the epithelial barrier function.

The cultural production of cities: Rhetoric or reality? Lessons from Glasgow

Our cities are under great strain to gain competitive advantage in today's global climate, in which the function of place marketing has never been greater. One of the most prevalent dimensions is the notion of the cultural city, where cities essentially market themselves based on both their traditional and contemporary cultural heritage. A key mechanism is the European Capital of Culture (ECOC) award, a potential catalyst for economic, physical, social and cultural growth. But to what extent does the complex nature of culture translate real change within the urban environment? In light of Liverpool's recent award as ECOC 2008 and the scale of current retail and leisure development in the city, this paper draws on the experiences of Glasgow's ECOC 1990 award. Seventeen years on from Glasgow's success, an event that has stimulated much debate, the city has now won the bid to host the Commonwealth Games in 2014. The paper discusses what lessons today's UK cities, like Liverpool, can learn from the Glasgow model, and the impact such hallmark events can have in achieving sustainable urban growth. Concludes that through applying the thoughts of Short (1996) that with such events there will always be a dichotomy between the rhetoric and the reality, we must not underestimate the complexity of urban culture, but still embrace the long-term sustainable potential that events like the ECOC can bring to the urban environment.

Subglacial comminution in the deforming bed: Inferences from SEM analysis

This study investigates the variations in erosional processes beneath Briksdalsbreen; a Norwegian valley glacier, with a thin coarse grained deforming bed. The subglacial zone was investigated in situ, close to the central glacial flow line (Site A) and close to the valley wall (Site B), via boreholes. The till was collected using two different sediment samplers and the bed was examined using a borehole video camera. In order to evaluate how representative borehole sampling was of the subglacial environment, the results from in situ subglacial samples were compared with random samples taken from an exposed subglacial surface in the glacier foreland, as well as a sample taken from the site after glacier retreat. The results indicated that the texture of the exposed subglacial surface was similar to in situ samples from subglacial Site B (close to the valley wall), and that the samples collected with the ‘small’ sediment sampler had the closest fit. SEM analysis revealed eroded quartz grains at both sites as a result of rotation (abrasion) and fracture. The samples from close to the valley wall were very poorly sorted, with evidence for rounding and preservation of pre-weathered surfaces, which suggest that a relatively simple pattern of erosion from crushing to rotation dominated. However, the till from the centre of the glacier was better sorted, more angular, and with few pre-weathered surfaces. We suggest that this results from a more complex glacial erosional history associated with greater strain and longer residence time within the deforming layer. When compared with other deformation tills, it was confirmed that there is a relationship between grain size and erosional style. Clay-rich tills show little comminution, fine sand-rich tills generate a significant silt component, whilst the coarse sand-rich tills at Briksdalsbreen showed complex deformational styles but no significant silt component.

Plate convergence at the westernmost Philippine Sea Plate

To understand the convergent characteristics of the westernmost plate boundary between the Philippine Sea Plate (PSP) and Eurasian Plate (EP), we have calculated the stress states of plate motion by focal mechanisms. Cataloged by the Harvard centroid moment tensor solutions (Harvard CMT) and the Broadband Array in Taiwan (BATS) moment tensor, 251 focal mechanisms are used to determine the azimuths of the principal stress axes. We first used all the data to derive the mean stress tensor of the study area. The inversion result shows that the stress regime has a maximum compression along the direction of azimuth N299°. This result is consistent with the general direction of the rigid plate motion between the PSP and EP in the study area. In order to understand the spatial variation of the regional stress pattern, we divided the study area into six sub-areas (blocks A to F) based on the feature of the free-air gravity anomaly. We compare the compressive directions obtained from the stress inversion with the plate motions calculated by the Euler pole and the Global Positioning System (GPS) analysis. As a result, the azimuth of the maximum stress axis, σ 1, generally agrees with the directions of the theoretical plate motion and GPS velocity vectors except block C (Lanhsu region) and block F (Ilan plain region). The discrepancy of convergent direction near the Ilan plain region is probably caused by the rifting of the Okinawa Trough. The deviation of the σ 1 azimuth in the Lanhsu region could be attributed to a southwestward extrusion of the Luzon Arc (LA) block between 21°N and 22°N whose northern boundary may be associated with the right-lateral NE–SW trending fault (i.e. Huatung Fault, HF) along the Taitung Canyon. Comparing the σ 1 stress patterns between block C and block D, great strain energy along HF may not be completely released yet. Alternatively, the upper crust of block C may significantly have decoupled from its lower crust or uppermost mantle.

Semi-solid microstructure evolution during reheating of aluminum A356 alloy deformed severely by ECAP

Semi-solid metal forming is a new developing technology that has some advantages in relation to other forming and casting technologies like high pressure die casting. This process contains three main steps: feedstock manufacturing, reheating and forming. Producing feedstocks with non-dendritic and spherical microstructure is one of the considerable factors in semi-solid forming. Feedstock manufacturing can be carried out with casting methods and solid-state methods. In solid-state processes like SIMA, remelting stage and related contamination is eliminated which is especially useful for active metals. In this research, Al (A356) has been used and in order to induce strains, equal channel angular pressing (ECAP) has been utilized. ECAP is one of the most effective and practical sever plastic deformation (SPD) methods to induce a great strain. In this study specimens were ECAPed for one to four passes to examine the effect of strain on the morphology and shape factor of reheated alloy. Conclusions indicate that with increase of strain, sphericity of particles increases, their size will decrease and sphericity takes place in less reheating time.

The Mitchell Library Reading Room: a personal memoir about the 1960s to 1980s

The Mitchell Library at the State Library of New South Wales in Macquarie Street, Sydney, is one of the pre-eminent repositories of Australian and Pacific material in the world. This paper traces the author’s involvement with the Mitchell Library Reading Room from the 1960s, when she was a student, to the 1980s, when she was Mitchell Librarian. During those decades the Mitchell Library, once a quiet place of scholarship, became extremely busy and crowded with the exponential interest in studying and researching Australian history and issues, placing great strains on a collection which had never been adequately funded, staffed or resourced.

Dynamical behaviour and microstructural evolution of a nitrogen-alloyed austenitic stainless steel

The aim of this work is to study the mechanical properties of a nitrogen austenitic stainless steel (Uranus B66) and their relation to its microstructural evolution. Quasi-static (10 −3 s −1) and quasi-dynamic (1 s −1) compression tests have been carried out with a universal servo-hydraulic testing machine. Dynamic (>10 3 s −1) compression tests have been performed on a classical split-Hopkinson bar apparatus. These tests, which cover a wide range of plastic strain, show that the material has a high-strain hardening rate, a good ductility and a great strain rate sensitivity. The temperature sensitivity has been determined over a large range, going from 77 K to 673 K. Transmission electron microscopy (TEM) observations have been conducted in order to correlate the microstructure to the mechanical behaviour. Uranus B66 undergoes basically the same structure evolution during both quasi-static and dynamic compression tests. The plastic deformation is governed initially by planar gliding, followed by mechanical twinning when the dislocation density is saturated.

Did owner‐occupation lead to smaller families for interwar working‐class households?1

This article examines the links between working‐class home ownership and family limitation in interwar Britain. Purchasing a suburban house enabled families to buy into a new, aspirational model of working‐class respectability. Embracing this model entailed increased accommodation costs and higher levels of conspicuous consumption, placing great strains on many household budgets. Owner‐occupiers therefore sought to limit the size of their families in order to sustain their new lifestyles. Meanwhile the new suburban ideology strongly emphasized improved standards of childcare, based around creating a high‐quality domestic environment, and thus directly encouraged families to aim for fewer, but better‐resourced children.