Ankle fracture spur sign is pathognomonic for a variant ankle fracture.

Science.gov (United States)

Hinds, Richard M; Garner, Matthew R; Lazaro, Lionel E; Warner, Stephen J; Loftus, Michael L; Birnbaum, Jacqueline F; Burket, Jayme C; Lorich, Dean G

2015-02-01

The hyperplantarflexion variant ankle fracture is composed of a posterior tibial lip fracture with posterolateral and posteromedial fracture fragments separated by a vertical fracture line. This infrequently reported injury pattern often includes an associated "spur sign" or double cortical density at the inferomedial tibial metaphysis. The objective of this study was to quantitatively establish the association of the ankle fracture spur sign with the hyperplantarflexion variant ankle fracture. Our clinical database of operative ankle fractures was retrospectively reviewed for the incidence of hyperplantarflexion variant and nonvariant ankle fractures as determined by assessment of injury radiographs, preoperative advanced imaging, and intraoperative observation. Injury radiographs were then evaluated for the presence of the spur sign, and association between the spur sign and variant fractures was analyzed. The incidence of the hyperplantarflexion variant fracture among all ankle fractures was 6.7% (43/640). The spur sign was present in 79% (34/43) of variant fractures and absent in all nonvariant fractures, conferring a specificity of 100% in identifying variant fractures. Positive predictive value and negative predictive value were 100% and 99%, respectively. The ankle fracture spur sign was pathognomonic for the hyperplantarflexion variant ankle fracture. It is important to identify variant fractures preoperatively as patient positioning, operative approach, and fixation construct of variant fractures often differ from those employed for osteosynthesis of nonvariant fractures. Identification of the spur sign should prompt acquisition of advanced imaging to formulate an appropriate operative plan to address the variant fracture pattern. Level III, retrospective comparative study. © The Author(s) 2014.

Linking Scales in Plastic Deformation and Fracture

DEFF Research Database (Denmark)

Martinez-Paneda, Emilio; Niordson, Christian Frithiof; S. Deshpande, Vikram

2017-01-01

We investigate crack growth initiation and subsequent resistance in metallic materials by means of an implicit multi-scale approach. Strain gradient plasticity is employed to model the mechanical response of the solid so as to incorporate the role of geometrically necessary dislocations (GNDs......) and accurately capture plasticity at the small scales involved in crack tip deformation. The response ahead of the crack is described by means of a traction-separation law, which is characterized by the cohesive strength and the fracture energy. Results reveal that large gradients of plastic strain accumulatein...... the vicinity of the crack, elevating the dislocation density and the local stress. This stress elevation enhances crack propagation and significantly lowers the steady state fracture toughness with respect to conventional plasticity. Important insight is gained into fracture phenomena that cannot be explained...

The link between great earthquakes and the subduction of oceanic fracture zones

Directory of Open Access Journals (Sweden)

R. D. Müller

2012-12-01

Full Text Available Giant subduction earthquakes are known to occur in areas not previously identified as prone to high seismic risk. This highlights the need to better identify subduction zone segments potentially dominated by relatively long (up to 1000 yr and more recurrence times of giant earthquakes. We construct a model for the geometry of subduction coupling zones and combine it with global geophysical data sets to demonstrate that the occurrence of great (magnitude ≥ 8 subduction earthquakes is strongly biased towards regions associated with intersections of oceanic fracture zones and subduction zones. We use a computational recommendation technology, a type of information filtering system technique widely used in searching, sorting, classifying, and filtering very large, statistically skewed data sets on the Internet, to demonstrate a robust association and rule out a random effect. Fracture zone–subduction zone intersection regions, representing only 25% of the global subduction coupling zone, are linked with 13 of the 15 largest (magnitude M_w ≥ 8.6 and half of the 50 largest (magnitude M_w ≥ 8.4 earthquakes. In contrast, subducting volcanic ridges and chains are only biased towards smaller earthquakes (magnitude < 8. The associations captured by our statistical analysis can be conceptually related to physical differences between subducting fracture zones and volcanic chains/ridges. Fracture zones are characterised by laterally continuous, uplifted ridges that represent normal ocean crust with a high degree of structural integrity, causing strong, persistent coupling in the subduction interface. Smaller volcanic ridges and chains have a relatively fragile heterogeneous internal structure and are separated from the underlying ocean crust by a detachment interface, resulting in weak coupling and relatively small earthquakes, providing a conceptual basis for the observed dichotomy.

Tensile and fracture behavior of polymer foams

International Nuclear Information System (INIS)

Kabir, Md. E.; Saha, M.C.; Jeelani, S.

2006-01-01

Tensile and mode-I fracture behavior of cross-linked polyvinyl chloride (PVC) and rigid polyurethane (PUR) foams are examined. Tension tests are performed using prismatic bar specimens and mode-I fracture tests are performed using single edge notched bend (SENB) specimens under three-point bending. Test specimens are prepared from PVC foams with three densities and two different levels of cross-linking, and PUR foam with one density. Tension and quasi-static fracture tests are performed using a Zwick/Rowell test machine. Dynamic fracture tests are performed using a DYNATUP model 8210 instrumented drop-tower test set up at three different impact energy levels. Various parameters such as specimen size, loading rate, foam density, cross-linking, crack length, cell orientation (flow and rise-direction) and solid polymer material are studied. It is found that foam density and solid polymer material have a significant effect on tensile strength, modulus, and fracture toughness of polymer foams. Level of polymer cross-linking is also found to have a significant effect on fracture toughness. The presence of cracks in the rise- and flow direction as well as loading rate has minimal effect. Dynamic fracture behavior is found to be different as compared to quasi-static fracture behavior. Dynamic fracture toughness (K d ) increases with impact energy. Examination of fracture surfaces reveals that the fracture occurs in fairly brittle manner for all foam materials

NATO Advanced Study Institute on Disorder and Fracture

CERN Document Server

Roux, S; Guyon, E

1990-01-01

Fracture, and particularly brittle fracture, is a good example of an instability. For a homogeneous solid, subjected to a uniform stress field, a crack may appear anywhere in the structure once the threshold stress is reached. However, once a crack has been nucleated in some place, further damage in the solid will in most cases propagate from the initial crack, and not somewhere else in the solid. In this sense fracture is an unstable process. This property makes the process extremely sensitive to any heterogeneity present in the medium, which selects the location of the first crack nucleated. In particular, fracture appears to be very sensitive to disorder, which can favor or impede local cracks. Therefore, in most realistic cases, a good description of fracture mechanics should include the effect of disorder. Recently this need has motivated work in this direction starting from the usual description of fracture mechanics. Parallel with this first trend, statistical physics underwent a very important develop...

Correlation of microstructure and fracture toughness of advanced 9Cr/CrMoV dissimilarly welded joint

Energy Technology Data Exchange (ETDEWEB)

Guo, Qian [Shanghai Key Laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Lu, Fenggui, E-mail: Lfg119@sjtu.edu.cn [Shanghai Key Laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Liu, Xia [Shanghai Turbine Plant of Shanghai Electric Power Generation Equipment Co. Ltd., Shanghai 200240 (China); Yang, Renjie [Shanghai Turbine Works Company, Shanghai 200240 (China); Cui, Haichao [Shanghai Key Laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Gao, Yulai, E-mail: ylgao@shu.edu.cn [State Key Laboratory of Advanced Special Steels, Shanghai University, Shanghai 200072 (China)

2015-06-25

In this paper, the fracture toughness and the related microstructure characteristics of dissimilarly welded joint manufactured by advanced 9Cr and CrMoV steels were systematically investigated. The dissimilarly welded joint was fabricated by narrow gap submerged arc welding (NG-SAW) applying multi-layer and multi-pass technique. Fracture toughness, as one of the most important property to assess the reliability of welded joint, was studied for different regions including CrMoV base metal (CrMoV-BM), heat affected zone (HAZ) of CrMoV side (CrMoV-HAZ), weld metal (WM), heat affected zone of 9Cr side (9Cr-HAZ) and 9Cr base metal (9Cr-BM). It was found that the fracture toughness of CrMoV-BM, CrMoV-HAZ and WM was better than that of 9Cr-HAZ and 9Cr-BM. In order to illustrate these results, the microstructure of the whole welded joint was observed by optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM) detailedly. It was found that the fine high-temperature tempered martensite and bainite in WM, CrMoV-BM and CrMoV-HAZ contribute to the higher fracture toughness, while lower fracture toughness for 9Cr-BM and HAZ was caused by coarse tempered lath-martensite. Furthermore, the fracture morphology showed that ductile fracture occurred in WM and CrMoV side, while brittle fracture appeared in BM and HAZ of 9Cr side.

Advanced Hydraulic Fracturing Technology for Unconventional Tight Gas Reservoirs

Energy Technology Data Exchange (ETDEWEB)

Stephen Holditch; A. Daniel Hill; D. Zhu

2007-06-19

The objectives of this project are to develop and test new techniques for creating extensive, conductive hydraulic fractures in unconventional tight gas reservoirs by statistically assessing the productivity achieved in hundreds of field treatments with a variety of current fracturing practices ranging from 'water fracs' to conventional gel fracture treatments; by laboratory measurements of the conductivity created with high rate proppant fracturing using an entirely new conductivity test - the 'dynamic fracture conductivity test'; and by developing design models to implement the optimal fracture treatments determined from the field assessment and the laboratory measurements. One of the tasks of this project is to create an 'advisor' or expert system for completion, production and stimulation of tight gas reservoirs. A central part of this study is an extensive survey of the productivity of hundreds of tight gas wells that have been hydraulically fractured. We have been doing an extensive literature search of the SPE eLibrary, DOE, Gas Technology Institute (GTI), Bureau of Economic Geology and IHS Energy, for publicly available technical reports about procedures of drilling, completion and production of the tight gas wells. We have downloaded numerous papers and read and summarized the information to build a database that will contain field treatment data, organized by geographic location, and hydraulic fracture treatment design data, organized by the treatment type. We have conducted experimental study on 'dynamic fracture conductivity' created when proppant slurries are pumped into hydraulic fractures in tight gas sands. Unlike conventional fracture conductivity tests in which proppant is loaded into the fracture artificially; we pump proppant/frac fluid slurries into a fracture cell, dynamically placing the proppant just as it occurs in the field. From such tests, we expect to gain new insights into some of the critical

"Ultra"-Fast Fracture Strength of Advanced Structural Ceramic Materials Studied at Elevated Temperatures

Science.gov (United States)

Choi, Sung R.; Gyekenyesi, John P.

1999-01-01

The accurate determination of inert strength is important in reliable life prediction of structural ceramic components. At ambient temperature, the inert strength of a brittle material is typically regarded as free of the effects of slow crack growth due to stress corrosion. Therefore, the inert strength can be determined either by eliminating active species, especially moisture, with an appropriate inert medium, or by using a very high test rate. However, at elevated temperatures, the concept or definition of the inert strength of brittle ceramic materials is not clear, since temperature itself is a degrading environment, resulting in strength degradation through slow crack growth and/or creep. Since the mechanism to control strength is rate-dependent viscous flow, the only conceivable way to determine the inert strength at elevated temperatures is to utilize a very fast test rate that either minimizes the time for or eliminates slow crack growth. Few experimental studies have measured the elevated-temperature, inert (or "ultra"-fast fracture) strength of advanced ceramics. At the NASA Lewis Research Center, an experimental study was initiated to better understand the "ultra"-fast fracture strength behavior of advanced ceramics at elevated temperatures. Fourteen advanced ceramics - one alumina, eleven silicon nitrides, and two silicon carbides - have been tested using constant stress-rate (dynamic fatigue) testing in flexure with a series of stress rates including the "ultra"-fast stress rate of 33 000 MPa/sec with digitally controlled test frames. The results for these 14 advanced ceramics indicate that, notwithstanding possible changes in flaw populations as well as flaw configurations because of elevated temperatures, the strength at 33 000 MPa/sec approached the room-temperature strength or reached a higher value than that determined at the conventional test rate of 30 MPa/sec. On the basis of the experimental data, it can be stated that the elevated

Etude théorique et expérimentale de la liaison de deux puits par fracturation hydraulique Theoretical and Experimental Analysis of the Linking of Two Wells by Hydraulic Fracturing

Directory of Open Access Journals (Sweden)

Bouteca M.

2006-11-01

Full Text Available La nécessité de réaliser, dans une couche mince et située à plus de 1000 m de profondeur, une communication hydraulique ou pneumatique entre deux sondages verticaux, a conduit à l'étude d'une méthode basée sur la fracturation hydraulique des puits à relier. Une telle approche suppose que l'on connaisse ou que l'on contrôle la direction des fractures développées. Les techniques actuelles ne permettant pas d'apprécier la direction de fracture avec une précision suffisante, la méthode proposée vise à influencer favorablement cette direction. Elle est basée sur une modification des contraintes effectives en place par une injection préalable de fluide dans les puits à relier. Les résultats obtenus au moyen de calculs analytiques et numériques à deux dimensions sont présentés, ainsi que les expériences réalisées sur un modèle physique en laboratoire. In a thin layer and at a depth of more than 1000 meters, the need to create a hydraulic or pneumatic communication between two vertical boreholes led to research on a method based on hydraulic fracturing in the wells to be linked. Such an approach supposes that the direction of the fractures thus created must be known or controlled. Current techniques cannot be used to assess fracture direction with sufficient accuracy. The method proposed here aims to have a favorable influence on this direction. It is based on making a change in the effective stresses in situ by the prior injection of fluid into the wells to be linked. The results obtained by two-dimensional analytical and digital computing are described together with the experiments performed on a physical model in the laboratory.

The long-term functional outcome of type II odontoid fractures managed non-operatively.

LENUS (Irish Health Repository)

Butler, J S

2010-10-01

Odontoid fractures currently account for 9-15% of all adult cervical spine fractures, with type II fractures accounting for the majority of these injuries. Despite recent advances in internal fixation techniques, the management of type II fractures still remains controversial with advocates still supporting non-rigid immobilization as the definitive treatment of these injuries. At the NSIU, over an 11-year period between 1 July 1996 and 30 June 2006, 66 patients (n = 66) were treated by external immobilization for type II odontoid fractures. The medical records, radiographs and CT scans of all patients identified were reviewed. Clinical follow-up evaluation was performed using the Cervical Spine Outcomes Questionnaire (CSOQ). The objectives of this study were to evaluate the long-term functional outcome of patients suffering isolated type II odontoid fractures managed non-operatively and to correlate patient age and device type with clinical and functional outcome. Of the 66 patients, there were 42 males and 24 females (M:F = 1.75:1) managed non-operatively for type II odontoid fractures. The mean follow-up time was 66 months. Advancing age was highly correlated with poorer long-term functional outcomes when assessing neck pain (r = 0.19, P = 0.1219), shoulder and arm pain (r = 0.41, P = 0.0007), physical symptoms (r = 0.25, P = 0.472), functional disability (r = 0.24, P = 0.0476) and psychological distress (r = 0.41, P = 0.0007). Patients >65 years displayed a higher rate of pseudoarthrosis (21.43 vs. 1.92%) and established non-union (7.14 vs. 0%) than patients <65 years. The non-operative management of type II odontoid fractures is an effective and satisfactory method of treating type II odontoid fractures, particularly those of a stable nature. However, patients of advancing age have been demonstrated to have significantly poorer functional outcomes in the long term. This may be linked to higher rates of non-union.

Resolving controversies in hip fracture care: the need for large collaborative trials in hip fractures

NARCIS (Netherlands)

Bhandari, Mohit; Sprague, Sheila; Schemitsch, Emil H.; Einhorn, Thomas; Guyatt, Gordon H.; Haidukewych, George; Keating, John; Koval, Kenneth; Rosen, Clifford; Swiontkowski, Marc; Tornetta, Paul; Walter, Stephen D.; Motsitsi, Silas; Pei, Fuxing; Yang, Tian-fu; Zhou, Zong-ke; Arora, Shobha; Babhulkar, Sushrut; Bhargava, Rakesh; Desai, Mohan M.; Dhillon, Mandeep S.; Gill, Harpreet Singh; Goel, S. C.; Reddy, A. V. Gurava; Jain, Anil K.; Kalore, Niraj V.; Kammatkar, Nitin; Kumar, Vijay; Malhorta, Rajesh; Marthandam, S. S. K.; Pankaj, Amite; Patinharayil, Gopinathan; Rai, B. Sachidanand; Ramteke, Alankar Ambadas; Sancheti, Parag K.; Thakkar, Navin N.; Thomas, George S.; Robinson, Dror; Steinberg, Ely; Higuchi, Fujio; Kawamura, Sumito; Ohashi, Hirotsugu; Sawaguchi, Takeshi; Park, Myung-Sik; Yun, Ho Hyun; Poduval, Murali; Siddiqui, Ahmed; Chang, Je-Ken; Wang, Gwo-Jaw; Goslings, J. Carel

2009-01-01

Hip fractures are a significant cause of morbidity and mortality worldwide and the burden of disability associated with hip fractures globally vindicate the need for high-quality research to advance the care of patients with hip fractures. Historically, large, multi-centre randomized controlled

Short-term effects of teriparatide versus placebo on bone biomarkers, structure, and fracture healing in women with lower-extremity stress fractures: A pilot study.

Science.gov (United States)

Almirol, Ellen A; Chi, Lisa Y; Khurana, Bharti; Hurwitz, Shelley; Bluman, Eric M; Chiodo, Christopher; Matzkin, Elizabeth; Baima, Jennifer; LeBoff, Meryl S

2016-09-01

In this pilot, placebo-controlled study, we evaluated whether brief administration of teriparatide (TPTD) in premenopausal women with lower-extremity stress fractures would increase markers of bone formation in advance of bone resorption, improve bone structure, and hasten fracture healing according to magnetic resonance imaging (MRI). Premenopausal women with acute lower-extremity stress fractures were randomized to injection of TPTD 20-µg subcutaneous (s.c.) (n = 6) or placebo s.c. (n = 7) for 8 weeks. Biomarkers for bone formation N-terminal propeptide of type I procollagen (P1NP) and osteocalcin (OC) and resorption collagen type-1 cross-linked C-telopeptide (CTX) and collagen type 1 cross-linked N-telopeptide (NTX) were measured at baseline, 4 and 8 weeks. The area between the percent change of P1NP and CTX over study duration is defined as the anabolic window. To assess structural changes, peripheral quantitative computed topography (pQCT) was measured at baseline, 8 and 12 weeks at the unaffected tibia and distal radius. The MRI of the affected bone assessed stress fracture healing at baseline and 8 weeks. After 8 weeks of treatment, bone biomarkers P1NP and OC increased more in the TPTD- versus placebo-treated group (both p ≤ 0.01), resulting in a marked anabolic window (p ≤ 0.05). Results from pQCT demonstrated that TPTD-treated women showed a larger cortical area and thickness compared to placebo at the weight bearing tibial site, while placebo-treated women had a greater total tibia and cortical density. No changes at the radial sites were observed between groups. According to MRI, 83.3% of the TPTD- and 57.1% of the placebo-treated group had improved or healed stress fractures (p = 0.18). In this randomized, pilot study, brief administration of TPTD showed anabolic effects that TPTD may help hasten fracture healing in premenopausal women with lower-extremity stress fractures. Larger prospective studies are warranted to determine

Bone fractures in children and adolescents

International Nuclear Information System (INIS)

Otto, S.; Wiersbitzky, H.; Hosten, N.; Mutze, S.

2003-01-01

This article provides an overview of the characteristics of radiologic diagnosis of fractures in the pediatric age group. Following an introduction to skeletal development, radiographic imaging is presented. In addition, more advanced imaging modalities, such as ultrasound, CT and MRI, are discussed. It is illustrated how these methods advance the diagnostic process when projection radiography fails to provide a satisfactory diagnosis. A short description of the anatomical characteristics of the growing skeleton is used to explain the mechanisms causing the typical fractures. Finally, specific fractures are reviewed, with emphasis on the most frequent fractures, especially those involving the elbow. (orig.) [de

[Hip Fracture--Epidemiology, Management and Liaison Service. Risk factor for hip fracture].

Science.gov (United States)

Fujiwara, Saeko

2015-04-01

Many risk factors have been identified for hip fracture, including female, advanced age, osteoporosis, previous fractures, low body weight or low body mass index, alcohol drinking, smoking, family history of fractures, use of glucocorticoid, factors related to falls, and bone strength. The factors related to falls are number of fall, frail, post stroke, paralysis, muscle weakness, anti-anxiety drugs, anti-depression drugs, and sedatives. Dementia and respiratory disease and others have been reported to be risk factors for secondary hip fracture.

Fractured Petroleum Reservoirs

Energy Technology Data Exchange (ETDEWEB)

Firoozabadi, Dr. Abbas

2000-01-18

In this report the results of experiments of water injection in fractured porous media comprising a number of water-wet matrix blocks are reported for the first time. The blocks experience an advancing fracture-water level (FWL). Immersion-type experiments are performed for comparison; the dominant recovery mechanism changed from co-current to counter-current imbibition when the boundary conditions changed from advancing FWL to immersion-type. Single block experiments of co-current and counter-current imbibition was performed and co-current imbibition leads to more efficient recovery was found.

RECENT ADVANCES IN NATURALLY FRACTURED RESERVOIR MODELING

OpenAIRE

ORDOÑEZ, A; PEÑUELA, G; IDROBO, E. A; MEDINA, C. E

2001-01-01

Large amounts of oil reserves are contained in naturally fractured reservoirs. Most of these hydrocarbon volumes have been left behind because of the poor knowledge and/or description methodology of those reservoirs. This lack of knowledge has lead to the nonexistence of good quantitative models for this complicated type of reservoirs. The complexity of naturally fractured reservoirs causes the need for integration of all existing information at all scales (drilling, well logging, seismic, we...

Identification of incident poisoning, fracture and burn events using linked primary care, secondary care and mortality data from England: implications for research and surveillance.

Science.gov (United States)

Baker, Ruth; Tata, Laila J; Kendrick, Denise; Orton, Elizabeth

2016-02-01

English national injury data collection systems are restricted to hospitalisations and deaths. With recent linkage of a large primary care database, the Clinical Practice Research Datalink (CPRD), with secondary care and mortality data, we aimed to assess the utility of linked data for injury research and surveillance by examining recording patterns and comparing incidence of common injuries across data sources. The incidence of poisonings, fractures and burns was estimated for a cohort of 2 147 853 0-24 year olds using CPRD linked to Hospital Episode Statistics (HES) and Office for National Statistics (ONS) mortality data between 1997 and 2012. Time-based algorithms were developed to identify incident events, distinguishing between repeat follow-up records for the same injury and those for a new event. We identified 42 985 poisoning, 185 517 fracture and 36 719 burn events in linked CPRD-HES-ONS data; incidence rates were 41.9 per 10 000 person-years (95% CI 41.4 to 42.4), 180.8 (179.8-181.7) and 35.8 (35.4-36.1), respectively. Of the injuries, 22 628 (53%) poisonings, 139 662 (75%) fractures and 33 462 (91%) burns were only recorded within CPRD. Only 16% of deaths from poisoning (n=106) or fracture (n=58) recorded in ONS were recorded within CPRD and/or HES records. None of the 10 deaths from burns were recorded in CPRD or HES records. It is essential to use linked primary care, hospitalisation and deaths data to estimate injury burden, as many injury events are only captured within a single data source. Linked routinely collected data offer an immediate and affordable mechanism for injury surveillance and analyses of population-based injury epidemiology in England. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Advanced hydraulic fracturing methods to create in situ reactive barriers

International Nuclear Information System (INIS)

Murdoch, L.

1997-01-01

This article describes the use of hydraulic fracturing to increase permeability in geologic formations where in-situ remedial action of contaminant plumes will be performed. Several in-situ treatment strategies are discussed including the use of hydraulic fracturing to create in situ redox zones for treatment of organics and inorganics. Hydraulic fracturing methods offer a mechanism for the in-situ treatment of gently dipping layers of reactive compounds. Specialized methods using real-time monitoring and a high-energy jet during fracturing allow the form of the fracture to be influenced, such as creation of assymmetric fractures beneath potential sources (i.e. tanks, pits, buildings) that should not be penetrated by boring. Some examples of field applications of this technique such as creating fractures filled with zero-valent iron to reductively dechlorinate halogenated hydrocarbons, and the use of granular activated carbon to adsorb compounds are discussed

The effect of advanced ultrasonic forging on fatigue fracture mechanisms of welded Ti-6A1-4V alloy

Science.gov (United States)

Smirnova, A.; Pochivalov, Yu.; Panin, V.; Panin, S.; Eremin, A.; Gorbunov, A.

2017-12-01

The current study is devoted to application of advanced postwelding ultrasonic forging to joints formed by laser welding of Ti-6A1-4V alloy in order to enhance their mechanical properties and fatigue durability. Low cycle fatigue tests were performed via digital image correlation technique used to obtain strain fields and in situ characterization of deformation, crack growth and fracture. Fracture surfaces were studied by SEM analysis accompanied with calculation of fracture patterns percentage. The fatigue tests demonstrate the high increase in the number of cycles until fracture (from 17 000 to 32 000 cycles) which could be explained by high ductility of welded material after treatment. This leads to lower fatigue crack growth rate due to higher energy dissipation. The obtained effect is attributable only for small cracks on micro-/mesoscales and fails to play a significant role for macro cracks.

Epidemiology of metatarsal stress fractures versus tibial and femoral stress fractures during elite training.

Science.gov (United States)

Finestone, Aharon; Milgrom, Charles; Wolf, Omer; Petrov, Kaloyan; Evans, Rachel; Moran, Daniel

2011-01-01

The training of elite infantry recruits takes a year or more. Stress fractures are known to be endemic in their basic training and the clinical presentation of tibial, femoral, and metatarsal stress fractures are different. Stress fracture incidence during the subsequent progressively more demanding training is not known. The study hypothesis was that after an adaptation period, the incidence of stress fractures during the course of 1 year of elite infantry training would fall in spite of the increasingly demanding training. Seventy-six male elite infantry recruits were followed for the development of stress fractures during a progressively more difficult training program composed of basic training (1 to 14 weeks), advanced training (14 to 26 weeks), and unit training (26 to 52 weeks). Subjects were reviewed regularly and those with clinical suspicion of stress fracture were assessed using bone scan and X-rays. The incidence of stress fractures was 20% during basic training, 14% during advanced training and 23% during unit training. There was a statistically significant difference in the incidence of tibial and femoral stress fractures versus metatarsal stress fractures before and after the completion of phase II training at week 26 (p=0.0001). Seventy-eight percent of the stress fractures during phases I and II training were either tibial or femoral, while 91% of the stress fractures in phase III training were metatarsal. Prior participation in ball sports (p=0.02) and greater tibial length (p=0.05) were protective factors for stress fracture. The study hypothesis that after a period of soldier adaptation, the incidence of stress fractures would decrease in spite of the increasingly demanding elite infantry training was found to be true for tibial and femoral fractures after 6 months of training but not for metatarsal stress fractures. Further studies are required to understand the mechanism of this difference but physicians and others treating stress fractures

Radiotherapy of pathologic fractures and skeletal lesions bearing the risk of fracture

International Nuclear Information System (INIS)

Rieden, K.; Kober, B.; Mende, U.; Zum Winkel, K.

1986-01-01

Radiotherapy is of great importance in the treatment of pathologic fractures and skeletal lesions bearing the risk of fracture which are induced by malignomas, especially if these are in an advanced stage. In dependence on site and extent of skeletal destruction as well as on the general tumor dissemination, it can be distinguished between palliative radiotherapy and curative radiotherapy aiming at analgesia and remineralization. A retrospective analysis of 27 pathologic fractures and 56 skeletal lesions bearing the risk of fracture in malignoma patients showed an analgetic effect obtained by radiotherapy in 67% of pathological fractures and in 80% of skeletal lesions bearing the risk of fracture, whereas a remineralization could be demonstrated for 33% of pathological fractures and 50% of destructions bearing the risk of fracture. A stabilization of destructions progressing before therapy was found in 55% of pathological fractures and 40% of skeletal lesions bearing the risk of fracture. Thus a partial loading, supported by orthopedic prostheses, was possible for more than 50% of all patients. (orig.) [de

Multidetector Computed Tomography of Cervical Spine Fractures in Ankylosing Spondylitis

Energy Technology Data Exchange (ETDEWEB)

Koivikko, M.P.; Kiuru, M.J.; Koskinen, S.K. [Helsinki Univ. Central Hospital, Toeoeloe Trauma Center (Finland). Dept. of Radiology

2004-11-01

Purpose: To analyze multidetector computed tomography (MDCT) cervical spine findings in trauma patients with advanced ankylosing spondylitis (AS). Material and Methods: Using PACS, 2282 cervical spine MDCT examinations requested by emergency room physicians were found during a period of 3 years. Of these patients, 18 (16 M, aged 41-87, mean 57 years) had advanced AS. Primary imaging included radiography in 12 and MRI in 11 patients. Results: MDCT detected one facet joint subluxation and 31 fractures in 17 patients: 14 transverse fractures, 8 spinous process fractures, 2 Jefferson's fractures, 1 type I and 2 type II odontoid process fractures, and 1 each: atlanto-occipital joint fracture and C2 laminar fracture plus isolated transverse process and facet joint fractures. Radiographs detected 48% and MRI 60% of the fractures. MRI detected all transverse and odontoid fractures, demonstrating spinal cord abnormalities in 72%. Conclusion: MDCT is superior to plain radiographs or MRI, showing significantly more injuries and yielding more information on fracture morphology. MRI is valuable, however, in evaluating the spinal cord and soft-tissue injuries. Fractures in advanced AS often show an abnormal orientation and are frequently associated with spinal cord injuries. In these patients, for any suspected cervical spine injuries, MDCT is therefore the imaging modality of choice.

Dependence of the mechanical fracture energy of the polymeric composite material from the mixture of filler fractions

Directory of Open Access Journals (Sweden)

E. M. Nurullaev

2015-01-01

Full Text Available This paper for the first time presents an equation for calculating the mechanical fracture energy of the polymeric composite material (PCM with regard to the basic formulation parameters. By means of the developed computer program the authors calculated the mechanical fracture energy of the polymer binder of the 3D cross-linked plasticized elastomer filled with multifractional silica. The solution of the integral equation was implemented using the corresponding dependence of stress on relative elongation at uniaxial tension. Engineering application of the theory was considered with respect to asphalt road covering. The authors proposed a generalized dependence of ruptural deformation of the polymer binder from the effective concentration of chemical and physical (intermolecular bonds for calculating the mechanical fracture energy of available and advanced PCMs as filled elastomers.

Creep fracture and creep-fatigue fracture in ceramics and ceramic composites

International Nuclear Information System (INIS)

Suresh, S.

1993-01-01

This paper summarizes recent advances in the areas of subcritical crack growth in ceramics subjected to static and cyclic loads at elevated temperatures. Attention is devoted to the specific role of pre-existing and in-situ-formed glass films in influencing creep fracture and creep-fatigue fracture. Experimental results on the effects of cyclic frequency and load ratio, along with detailed transmission electron microscopy of crack-tip and crack-wake damage are highlighted. Some general conclusions are drawn about the dependence of high-temperature damage tolerance on interfacial glass films and about the susceptibility of ceramic materials to cyclic fatigue fracture

Streaming potential modeling in fractured rock: Insights into the identification of hydraulically active fractures

Science.gov (United States)

Roubinet, D.; Linde, N.; Jougnot, D.; Irving, J.

2016-05-01

Numerous field experiments suggest that the self-potential (SP) geophysical method may allow for the detection of hydraulically active fractures and provide information about fracture properties. However, a lack of suitable numerical tools for modeling streaming potentials in fractured media prevents quantitative interpretation and limits our understanding of how the SP method can be used in this regard. To address this issue, we present a highly efficient two-dimensional discrete-dual-porosity approach for solving the fluid flow and associated self-potential problems in fractured rock. Our approach is specifically designed for complex fracture networks that cannot be investigated using standard numerical methods. We then simulate SP signals associated with pumping conditions for a number of examples to show that (i) accounting for matrix fluid flow is essential for accurate SP modeling and (ii) the sensitivity of SP to hydraulically active fractures is intimately linked with fracture-matrix fluid interactions. This implies that fractures associated with strong SP amplitudes are likely to be hydraulically conductive, attracting fluid flow from the surrounding matrix.

Atypical femoral fractures related to bisphosphonate therapy

Directory of Open Access Journals (Sweden)

Tarun Pankaj Jain

2012-01-01

Full Text Available Bisphosphonates (BP are a commonly prescribed class of drugs for the prevention of osteoporosis-related fractures. Paradoxically, however, they have recently been linked to atypical fractures in the shaft of the femur. Since many physicians including radiologists, are not aware of this entity, the incidence is likely underreported. These fractures usually occur in the sub-trochanteric region of the femur in the setting of low-energy trauma. It starts as a fracture line involving the lateral cortex and then progresses medially to give rise to a complete fracture. The fracture line is usually transverse, and there is a medial spike associated with a complete fracture. These fractures can be bilateral. Awareness of these atypical fractures and their radiological appearance should enable their early and accurate detection and thus lead to specific treatment.

Preliminary fracture analysis of the core pressure boundary tube for the Advanced Neutron Source Research Reactor

International Nuclear Information System (INIS)

Schulz, K.C.

1995-08-01

The outer core pressure boundary tube (CPBT) of the Advanced neutron Source (ANS) reactor being designed at Oak Ridge National Laboratory is currently specified as being composed of 6061-T6 aluminum. ASME Boiler and Pressure Vessel Code fracture analysis rules for nuclear components are based on the use of ferritic steels; the expressions, tables, charts and equations were all developed from tests and analyses conducted for ferritic steels. Because of the nature of the Code, design with thin aluminum requires analytical approaches that do not directly follow the Code. The intent of this report is to present a methodology comparable to the ASME Code for ensuring the prevention of nonductile fracture of the CPBT in the ANS reactor. 6061-T6 aluminum is known to be a relatively brittle material; the linear elastic fracture mechanics (LEFM) approach is utilized to determine allowable flaw sizes for the CPBT. A J-analysis following the procedure developed by the Electric Power Research Institute was conducted as a check; the results matched those for the LEFM analysis for the cases analyzed. Since 6061-T6 is known to embrittle when irradiated, the reduction in K Q due to irradiation is considered in the analysis. In anticipation of probable requirements regarding maximum allowable flaw size, a survey of nondestructive inspection capabilities is also presented. A discussion of probabilistic fracture mechanics approaches, principally Monte Carlo techniques, is included in this report as an introduction to what quantifying the probability of nonductile failure of the CPBT may entail

Arthroplasty for Unreconstructable Acute Fractures and Failed Fracture Fixation About the Hip and Knee in the Active Elderly: A New Paradigm.

Science.gov (United States)

Kyle, Richard F; Duwelius, Paul J; Haidukewych, George J; Schmidt, Andrew H

2017-02-15

The techniques, materials, and designs for total joint arthroplasty underwent major improvements in the past 30 years. During this time, trauma surgeons classified the severity of fractures as well as identified certain articular fractures that do not have good outcomes and have a high rate of failure after internal fixation. Advanced improvements in arthroplasty have increased its reliability and longevity. Total joint arthroplasty is becoming a standard of care for some acute articular fractures, particularly displaced femoral neck fractures in the active elderly. Total joint arthroplasty also has become the standard of care after failed internal fixation in patients who have very complicated fractures about the knee, hip, and shoulder. As the population ages, fractures worldwide continue to rapidly increase. Elderly patients have a high risk for fractures that result from falls because of their poor bone quality. The current active elderly population participates in higher risk activities than previous elderly populations, which places them at risk for more injuries. This has become both a worldwide healthcare problem and an economic problem. Surgeons need to manage fractures in the active elderly with the latest advancements in technology and patient selection to ensure rapid recovery and the reduction of complications.

Vitamin D and nutritional status are related to bone fractures in alcoholics.

Science.gov (United States)

González-Reimers, Emilio; Alvisa-Negrín, Julio; Santolaria-Fernández, Francisco; Candelaria Martín-González, M; Hernández-Betancor, Iván; Fernández-Rodríguez, Camino M; Viña-Rodríguez, J; González-Díaz, Antonieta

2011-01-01

Bone fractures are common in alcoholics. To analyse which factors (ethanol consumption; liver function impairment; bone densitometry; hormone changes; nutritional status, and disrupted social links and altered eating habits) are related to bone fractures in 90 alcoholic men admitted to our hospitalization unit because of organic problems. Bone homoeostasis-related hormones were measured in patients and age- and sex-matched controls. Whole-body densitometry was performed by a Hologic QDR-2000 (Waltham, MA, USA) densitometer, recording bone mineral density (BMD) and fat and lean mass; nutritional status and liver function were assessed. The presence of prevalent fractures was assessed by anamnesis and chest X-ray film. Forty-nine patients presented at least one fracture. We failed to find differences between patients with and without fractures regarding BMD parameters. Differences regarding fat mass were absent, but lean mass was lower among patients with bone fracture. The presence of fracture was significantly associated with impaired subjective nutritional evaluation (χ² = 5.79, P = 0.016), lower vitamin D levels (Z = 2.98, P = 0.003) and irregular eating habits (χ² = 5.32, P = 0.02). Reduced lean mass and fat mass, and altered eating habits were more prevalent among patients with only rib fractures (n = 36) than in patients with multiple fractures and/or fractures affecting other bones (n = 13). These last were more closely related to decompensated liver disease. Serum vitamin D levels showed a significant relationship with handgrip strength (ρ = 0.26, P = 0.023) and lean mass at different parts of the body, but not with fat mass. By logistic regression analysis, only vitamin D and subjective nutritional evaluation were significantly, independently related with fractures. Prevalent fractures are common among heavy alcoholics. Their presence is related more closely to nutritional status, lean mass and vitamin D levels than to BMD. Lean mass is more reduced

[Periprosthetic knee fractures].

Science.gov (United States)

Mittlmeier, T; Beck, M; Bosch, U; Wichelhaus, A

2016-01-01

The cumulative incidence of periprosthetic fractures around the knee is increasing further because of an extended indication for knee replacement, previous revision arthroplasty, rising life expectancy and comorbidities. The relevance of local parameters such as malalignment, osseous defects, neighbouring implants, aseptic loosening and low-grade infections may sometimes be hidden behind the manifestation of a traumatic fracture. A differentiated diagnostic approach before the treatment of a periprosthetic fracture is of paramount importance, while the physician in-charge should also have particular expertise in fracture treatment and in advanced techniques of revision endoprosthetics. The following work gives an overview of this topic. Valid classifications are available for categorising periprosthetic fractures of the femur, the tibia and the patella respectively, which are helpful for the selection of treatment. With the wide-ranging modern treatment portfolio bearing in mind the substantial rate of complications and the heterogeneous functional outcome, the adequate analysis of fracture aetiology and the corresponding transformation into an individualised treatment concept offer the chance of an acceptable functional restoration of the patient at early full weight-bearing and prolonged implant survival. The management of complications is crucial to the final outcome.

Acetabular Fracture

Directory of Open Access Journals (Sweden)

Chad Correa

2017-09-01

Full Text Available History of present illness: A 77-year-old female presented to her primary care physician (PCP with right hip pain after a mechanical fall. She did not lose consciousness or have any other traumatic injuries. She was unable to ambulate post-fall, so X-rays were ordered by her PCP. Her X-rays were concerning for a right acetabular fracture (see purple arrows, so the patient was referred to the emergency department where a computed tomography (CT scan was ordered. Significant findings: The non-contrast CT images show a minimally displaced comminuted fracture of the right acetabulum involving the acetabular roof, medial and anterior walls (red arrows, with associated obturator muscle hematoma (blue oval. Discussion: Acetabular fractures are quite rare. There are 37 pelvic fractures per 100,000 people in the United States annually, and only 10% of these involve the acetabulum. They occur more frequently in the elderly totaling an estimated 4,000 per year. High-energy trauma is the primary cause of acetabular fractures in younger individuals and these fractures are commonly associated with other fractures and pelvic ring disruptions. Fractures secondary to moderate or minimal trauma are increasingly of concern in patients of advanced age.1 Classification of acetabular fractures can be challenging. However, the approach can be simplified by remembering the three basic types of acetabular fractures (column, transverse, and wall and their corresponding radiologic views. First, column fractures should be evaluated with coronally oriented CT images. This type of fracture demonstrates a coronal fracture line running caudad to craniad, essentially breaking the acetabulum into two halves: a front half and a back half. Secondly, transverse fractures should be evaluated by sagittally oriented CT images. By definition, a transverse fracture separates the acetabulum into superior and inferior halves with the fracture line extending from anterior to posterior

Risk Factors for Pelvic Insufficiency Fractures in Locally Advanced Cervical Cancer Following Intensity Modulated Radiation Therapy

DEFF Research Database (Denmark)

Ramlov, Anne; Pedersen, Erik Morre; Røhl, Lisbeth

2017-01-01

and underwent external beam radiation therapy with 45 Gy in 25 fractions (node-negative patients) or 50 Gy in 25 fractions with a simultaneous integrated boost of 60 Gy in 30 fractions (node-positive patients). Pulsed dose rate magnetic resonance imaging guided adaptive brachytherapy was given in addition......PURPOSE: To investigate the incidence of and risk factors for pelvic insufficiency fracture (PIF) after definitive chemoradiation therapy for locally advanced cervical cancer (LACC). METHODS AND MATERIALS: We analyzed 101 patients with LACC treated from 2008-2014. Patients received weekly cisplatin...

Ontology of fractures

Science.gov (United States)

Zhong, Jian; Aydina, Atilla; McGuinness, Deborah L.

2009-03-01

Fractures are fundamental structures in the Earth's crust and they can impact many societal and industrial activities including oil and gas exploration and production, aquifer management, CO 2 sequestration, waste isolation, the stabilization of engineering structures, and assessing natural hazards (earthquakes, volcanoes, and landslides). Therefore, an ontology which organizes the concepts of fractures could help facilitate a sound education within, and communication among, the highly diverse professional and academic community interested in the problems cited above. We developed a process-based ontology that makes explicit specifications about fractures, their properties, and the deformation mechanisms which lead to their formation and evolution. Our ontology emphasizes the relationships among concepts such as the factors that influence the mechanism(s) responsible for the formation and evolution of specific fracture types. Our ontology is a valuable resource with a potential to applications in a number of fields utilizing recent advances in Information Technology, specifically for digital data and information in computers, grids, and Web services.

Pre-fracture individual characteristics associated with high total health care costs after hip fracture.

Science.gov (United States)

Schousboe, J T; Paudel, M L; Taylor, B C; Kats, A M; Virnig, B A; Dowd, B E; Langsetmo, L; Ensrud, K E

2017-03-01

Older women with pre-fracture slow walk speed, high body mass index, and/or a high level of multimorbidity have significantly higher health care costs after hip fracture compared to those without those characteristics. Studies to investigate if targeted health care interventions for these individuals can reduce hip fracture costs are warranted. The aim of this study is to estimate the associations of individual pre-fracture characteristics with total health care costs after hip fracture, using Study of Osteoporotic Fractures (SOF) cohort data linked to Medicare claims. Our study population was 738 women age 70 and older enrolled in Medicare Fee for Service (FFS) who experienced an incident hip fracture between January 1, 1992 and December 31, 2009. We assessed pre-fracture individual characteristics at SOF study visits and estimated costs of hospitalizations, skilled nursing facility and inpatient rehabilitation stays, home health care visits, and outpatient utilization from Medicare FFS claims. We used generalized linear models to estimate the associations of predictor variables with total health care costs (2010 US dollars) after hip fracture. Median total health care costs for 1 year after hip fracture were $35,536 (inter-quartile range $24,830 to $50,903). Multivariable-adjusted total health care costs for 1 year after hip fracture were 14 % higher ($5256, 95 % CI $156 to $10,356) in those with walk speed total health care costs after hip fracture in older women. Studies to investigate if targeted health care interventions for these individuals can reduce the costs of hip fractures are warranted.

Collagen turnover after tibial fractures

DEFF Research Database (Denmark)

Joerring, S; Krogsgaard, M; Wilbek, H

1994-01-01

Collagen turnover after tibial fractures was examined in 16 patients with fracture of the tibial diaphysis and in 8 patients with fracture in the tibial condyle area by measuring sequential changes in serological markers of turnover of types I and III collagen for up to 26 weeks after fracture....... The markers were the carboxy-terminal extension peptide of type I procollagen (PICP), the amino-terminal extension peptide of type III procollagen (PIIINP), and the pyridinoline cross-linked carboxy-terminal telopeptide of type I collagen (ICTP). The latter is a new serum marker of degradation of type I...... collagen. A group comparison showed characteristic sequential changes in the turnover of types I and III collagen in fractures of the tibial diaphysis and tibial condyles. The turnover of type III collagen reached a maximum after 2 weeks in both groups. The synthesis of type I collagen reached a maximum...

Advances in treating exposed fractures.

Science.gov (United States)

Nogueira Giglio, Pedro; Fogaça Cristante, Alexandre; Ricardo Pécora, José; Partezani Helito, Camilo; Lei Munhoz Lima, Ana Lucia; Dos Santos Silva, Jorge

2015-01-01

The management of exposed fractures has been discussed since ancient times and remains of great interest to present-day orthopedics and traumatology. These injuries are still a challenge. Infection and nonunion are feared complications. Aspects of the diagnosis, classification and initial management are discussed here. Early administration of antibiotics, surgical cleaning and meticulous debridement are essential. The systemic conditions of patients with multiple trauma and the local conditions of the limb affected need to be taken into consideration. Early skeletal stabilization is necessary. Definitive fixation should be considered when possible and provisional fixation methods should be used when necessary. Early closure should be the aim, and flaps can be used for this purpose.

Diagnosis and management of hook of hamate fractures.

Science.gov (United States)

Kadar, Assaf; Bishop, Allen T; Suchyta, Marissa A; Moran, Steven L

2018-06-01

The purpose of this study was to evaluate the time to diagnosis and management of hook of hamate fractures in an era of advanced imaging. We performed a retrospective study of 51 patients treated for hook of hamate fractures. Patients were sent a quickDASH questionnaire regarding the outcomes of their treatment. Hook of hamate fractures were diagnosed with advanced imaging at a median of 27 days. Clinical findings of hook of hamate tenderness had better sensitivity than carpal tunnel-view radiographs. Nonunion occurred in 24% of patients with non-operative treatment and did not occur in the operative group. Both treatment groups achieved good clinical results, with a grip strength of 80% compared with the non-injured hand and a median quickDASH score of 2. Advanced imaging improved the time to diagnosis and treatment compared to historical case series. Nonunion is common in patients treated non-operatively. IV.

Correlation of transmissive fractures in pilot holes ONK-PH8 - PH12 and fracture traces mapped in ONKALO

International Nuclear Information System (INIS)

Palmen, J.; Nummela, J.; Ahokas, H.

2014-05-01

In a preceding study Posiva flow logging (PFL) with a 0.5 m test interval and 0.1 m steps has been used together with optical drillhole images and core logging fracture data for the exact determination of the depth of hydraulically conductive fractures in pilot holes. The fracture traces have been mapped from the ONKALO tunnel walls as a part of the systematic mapping. The mapping results has been digitized to a 3D tunnel layout in Surpac programme. The data integrity and fracture trace uniqueness has been verified by Datactica Oy and further collected to a database (RakokantaDatacticaPosiva20100607.mdb). Fractures mapped with leakage attribute have been defined as flowing, dripping, wet, or damp where the attribute is recorded. The fractures with no leakage attribute value appear to be non leaking. The water leaking surfaces on the ONKALO tunnel walls have been mapped sequentially and conclusively (once or twice a year) as a part of the Olkiluoto monitoring program (OMO) using an equal five step measure as used with fracture traces in systematic mapping. The PFL results correlated with core logging fracture data from the pilot holes ONK-PH8 - ONK-PH12 were in this work further correlated with the fractures mapped from the ONKALO tunnel walls. Each hydraulically conductive fracture of ONK-PH8 - ONK-PH12 was investigated and linked to ONKALO fracture of a coherent orientation and matching location, where such fracture trace was available. Also tunnel crosscutting fracture (TCF) data was used in combining, since the systematic mapping data was not yet available for the pilot holes ONK-PH11 and ONK-PH12 at the time of the evaluation. The main objective of the work was to identify the ONKALO fractures which correspond to the flow from fracture(s) identified with the PFL method in pilot holes and to collect basic information about the occurrence, frequency and orientation of water bearing fractures along the ONKALO tunnel. The correlated hydraulically conductive

Correlation of transmissive fractures in pilot holes ONK-PH8 - PH12 and fracture traces mapped in ONKALO

Energy Technology Data Exchange (ETDEWEB)

Palmen, J.; Nummela, J.; Ahokas, H. [Poeyry Finland Oy, Vantaa (Finland)

2014-05-15

In a preceding study Posiva flow logging (PFL) with a 0.5 m test interval and 0.1 m steps has been used together with optical drillhole images and core logging fracture data for the exact determination of the depth of hydraulically conductive fractures in pilot holes. The fracture traces have been mapped from the ONKALO tunnel walls as a part of the systematic mapping. The mapping results has been digitized to a 3D tunnel layout in Surpac programme. The data integrity and fracture trace uniqueness has been verified by Datactica Oy and further collected to a database (RakokantaDatacticaPosiva20100607.mdb). Fractures mapped with leakage attribute have been defined as flowing, dripping, wet, or damp where the attribute is recorded. The fractures with no leakage attribute value appear to be non leaking. The water leaking surfaces on the ONKALO tunnel walls have been mapped sequentially and conclusively (once or twice a year) as a part of the Olkiluoto monitoring program (OMO) using an equal five step measure as used with fracture traces in systematic mapping. The PFL results correlated with core logging fracture data from the pilot holes ONK-PH8 - ONK-PH12 were in this work further correlated with the fractures mapped from the ONKALO tunnel walls. Each hydraulically conductive fracture of ONK-PH8 - ONK-PH12 was investigated and linked to ONKALO fracture of a coherent orientation and matching location, where such fracture trace was available. Also tunnel crosscutting fracture (TCF) data was used in combining, since the systematic mapping data was not yet available for the pilot holes ONK-PH11 and ONK-PH12 at the time of the evaluation. The main objective of the work was to identify the ONKALO fractures which correspond to the flow from fracture(s) identified with the PFL method in pilot holes and to collect basic information about the occurrence, frequency and orientation of water bearing fractures along the ONKALO tunnel. The correlated hydraulically conductive

Seismic characteristics of tensile fracture growth induced by hydraulic fracturing

Science.gov (United States)

Eaton, D. W. S.; Van der Baan, M.; Boroumand, N.

2014-12-01

Hydraulic fracturing is a process of injecting high-pressure slurry into a rockmass to enhance its permeability. Variants of this process are used for unconventional oil and gas development, engineered geothermal systems and block-cave mining; similar processes occur within volcanic systems. Opening of hydraulic fractures is well documented by mineback trials and tiltmeter monitoring and is a physical requirement to accommodate the volume of injected fluid. Numerous microseismic monitoring investigations acquired in the audio-frequency band are interpreted to show a prevalence of shear-dominated failure mechanisms surrounding the tensile fracture. Moreover, the radiated seismic energy in the audio-frequency band appears to be a miniscule fraction (<< 1%) of the net injected energy, i.e., the integral of the product of fluid pressure and injection rate. We use a simple penny-shaped crack model as a predictive framework to describe seismic characteristics of tensile opening during hydraulic fracturing. This model provides a useful scaling relation that links seismic moment to effective fluid pressure within the crack. Based on downhole recordings corrected for attenuation, a significant fraction of observed microseismic events are characterized by S/P amplitude ratio < 5. Despite the relatively small aperture of the monitoring arrays, which precludes both full moment-tensor analysis and definitive identification of nodal planes or axes, this ratio provides a strong indication that observed microseismic source mechanisms have a component of tensile failure. In addition, we find some instances of periodic spectral notches that can be explained by an opening/closing failure mechanism, in which fracture propagation outpaces fluid velocity within the crack. Finally, aseismic growth of tensile fractures may be indicative of a scenario in which injected energy is consumed to create new fracture surfaces. Taken together, our observations and modeling provide evidence that

Prospective study of ankle and foot fractures in elderly women

Directory of Open Access Journals (Sweden)

Yadagiri Surender Rao

2015-01-01

Full Text Available The epidemiology of ankle fractures in old people is changing as time passes on. The incidence of ankle fractures increases with advancing age. The study conducted was among a rural popula-tion which comprised of 68 women (32 women with ankle fractures & 36 women with foot fractures. Patients studied were in the age group more than 50 years. The study highlights the etiological & risk factors for fractures of ankle & foot. The commonest ankle fracture was the lateral malleolar fracture & the commonest foot fracture was the 5th Metatarsal fracture. Diabetes is a risk factor which increases the occurrence of ankle and foot injuries.

Correlation of transmissive fractures in holes OL-PH1, ONK-PH2 .. ONK-PH7 and ONKALO tunnel fractures

International Nuclear Information System (INIS)

Palmen, J; Nummela, J.; Ahokas, H.

2011-02-01

In a preceding study Posiva flow logging (PFL) with a 0.5 m test interval and 10 cm steps has been used together with optical drillhole images and core logging fracture data for the exact determination of the depth of hydraulically conductive fractures in pilot holes. The fracture traces has been mapped from the ONKALO tunnel walls as a part of the systematic mapping. The mapping results has been digitized to a 3D tunnel layout in Surpac Vision programme. The data integrity and fracture trace uniqueness has been verified by Datactica Oy and further collected to a database (Rakokanta D atactica P osiva20091119.mdb). Water leakage of the mapped fractures exists as an attribute field for each fracture, but the value of the attribute has not been assessed conclusively. Those fractures mapped with leakage attribute have been defined as flowing, dripping, wet, or damp where the attribute is recorded. The fractures with no leakage attribute value appear to be dry (not leaking) or the information is not available (assessment was not performed). The water leaking surfaces on ONKALO tunnel wall have been mapped sequentially and conclusively (twice a year) as a part of the Olkiluoto monitoring program (OMO) using an equal five step measure as used with fracture traces in systematic mapping. The PFL results correlated with core logging fracture data from pilot holes OL-PH1 and ONK-PH2 .. ONK-PH7 were in this work further correlated with the fractures mapped from the ONKALO tunnel walls. Each hydraulically conductive fracture of OL-PH1 and ONK-PH2 - ONK-PH7 was investigated and linked to ONKALO fracture of a coherent orientation and matching location, where such fracture trace was available. The main objective of the work was to identify the ONKALO fractures which correspond to the flow from fracture(s) identified with the PFL method in pilot holes and to collect basic information about the occurrence, frequency and orientation of water bearing fractures along ONKALO tunnel

Evidence-based medicine: Mandible fractures.

Science.gov (United States)

Morrow, Brad T; Samson, Thomas D; Schubert, Warren; Mackay, Donald R

2014-12-01

After studying this article, the participant should be able to: 1. Describe the anatomy and subunits of the mandible. 2. Review the cause and epidemiology of mandible fractures. 3. Discuss the preoperative evaluation and diagnostic imaging. 4. Understand the principles and techniques of mandible fracture reduction and fixation. The management of mandibular fractures has undergone significant improvement because of advancements in plating technology, imaging, and instrumentation. As the techniques in management continue to evolve, it is imperative for the practicing physician to remain up-to-date with the growing body of scientific literature. The objective of this Maintenance of Certification article is to present a review of the literature so that the physician may make treatment recommendation based on the best evidence available. Pediatric fractures have been excluded from this article.

Seismic Characterizations of Fractures: Dynamic Diagnostics

Science.gov (United States)

Pyrak-Nolte, L. J.

2017-12-01

Fracture geometry controls fluid flow in a fracture, affects mechanical stability and influences energy partitioning that affects wave scattering. Our ability to detect and monitor fracture evolution is controlled by the frequency of the signal used to probe a fracture system, i.e. frequency selects the scales. No matter the frequency chosen, some set of discontinuities will be optimal for detection because different wavelengths sample different subsets of fractures. The select subset of fractures is based on the stiffness of the fractures which in turn is linked to fluid flow. A goal is obtaining information from scales outside the optimal detection regime. Fracture geometry trajectories are a potential approach to drive a fracture system across observation scales, i.e. moving systems between effective medium and scattering regimes. Dynamic trajectories (such as perturbing stress, fluid pressure, chemical alteration, etc.) can be used to perturb fracture geometry to enhance scattering or give rise to discrete modes that are intimately related to the micro-structural evolution of a fracture. However, identification of these signal features will require methods for identifying these micro-structural signatures in complicated scattered fields. Acknowledgment: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Geosciences Research Program under Award Number (DE-FG02-09ER16022).

Pathogenesis of osteoporotic hip fractures.

Science.gov (United States)

McClung, Michael R

2003-01-01

Osteoporosis is characterized late in the course of the disease by an increased risk of fracture, particularly in the elderly. It occurs in both sexes, affecting approximately 8 million women and 2 million men aged > or = 50 years (1). While low bone density is a predictor of fractures, it is not the only determinant of fracture risk. Other factors include advanced age, altered bone quality, a personal or family history of falls, frailty, poor eyesight, debilitating diseases, and high bone turnover. A diet with sufficient calcium and vitamin D is important to minimize bone loss and, along with regular exercise, to maintain muscle strength. Bisphosphonates have been shown to reduce the risk of hip fracture. For elderly patients, the use of hip protectors may be used as a treatment of last resort. Regardless of the age of the patient, individual patient risk factors must be considered to target appropriate treatment and prevent fracture.

Recent trends in fracture and damage mechanics

CERN Document Server

Zybell, Lutz

2016-01-01

This book covers a wide range of topics in fracture and damage mechanics. It presents historical perspectives as well as recent innovative developments, presented by peer reviewed contributions from internationally acknowledged authors.  The volume deals with the modeling of fracture and damage in smart materials, current industrial applications of fracture mechanics, and it explores advances in fracture testing methods. In addition, readers will discover trends in the field of local approach to fracture and approaches using analytical mechanics. Scholars in the fields of materials science, engineering and computational science will value this volume which is dedicated to Meinhard Kuna on the occasion of his 65th birthday in 2015. This book incorporates the proceedings of an international symposium that was organized to honor Meinhard Kuna’s contributions to the field of theoretical and applied fracture and damage mechanics.

Studies of Transport Properties of Fractures: Final Report

Energy Technology Data Exchange (ETDEWEB)

Stephen R. Brown

2006-06-30

We proposed to study several key factors controlling the character and evolution of fracture system permeability and transport processes. We suggest that due to surface roughness and the consequent channeling in single fractures and in fracture intersections, the tendency of a fracture system to plug up, remain permeable, or for permeability to increase due to chemical dissolution/precipitation conditions will depend strongly on the instantaneous flow channel geometry. This geometry will change as chemical interaction occurs, thus changing the permeability through time. To test this hypothesis and advance further understanding toward a predictive capability, we endeavored to physically model and analyze several configurations of flow and transport of inert and chemically active fluids through channels in single fractures and through fracture intersections. This was an integrated program utilizing quantitative observations of fractures and veins in drill core, quantitative and visual observations of flow and chemical dissolution and precipitation within replicas of real rough-walled fractures and fracture intersections, and numerical modeling via lattice Boltzmann methods.

Effects of simplifying fracture network representation on inert chemical migration in fracture-controlled aquifers

Science.gov (United States)

Wellman, Tristan; Shapiro, Allen M.; Hill, Mary C.

2009-01-01

While it is widely recognized that highly permeable 'large-scale' fractures dominate chemical migration in many fractured aquifers, recent studies suggest that the pervasive 'small-scale' fracturing once considered of less significance can be equally important for characterizing the spatial extent and residence time associated with transport processes. A detailed examination of chemical migration through fracture-controlled aquifers is used to advance this conceptual understanding. The influence of fracture structure is evaluated by quantifying the effects to transport caused by a systematic removal of fractures from three-dimensional discrete fracture models whose attributes are derived from geologic and hydrologic conditions at multiple field sites. Results indicate that the effects to transport caused by network simplification are sensitive to the fracture network characteristics, degree of network simplification, and plume travel distance, but primarily in an indirect sense since correlation to individual attributes is limited. Transport processes can be 'enhanced' or 'restricted' from network simplification meaning that the elimination of fractures may increase or decrease mass migration, mean travel time, dispersion, and tailing of the concentration plume. The results demonstrate why, for instance, chemical migration may not follow the classic advection-dispersion equation where dispersion approximates the effect of the ignored geologic structure as a strictly additive process to the mean flow. The analyses further reveal that the prediction error caused by fracture network simplification is reduced by at least 50% using the median estimate from an ensemble of simplified fracture network models, and that the error from network simplification is at least 70% less than the stochastic variability from multiple realizations. Copyright 2009 by the American Geophysical Union.

An Improved Rate-Transient Analysis Model of Multi-Fractured Horizontal Wells with Non-Uniform Hydraulic Fracture Properties

Directory of Open Access Journals (Sweden)

Youwei He

2018-02-01

Full Text Available Although technical advances in hydraulically fracturing and drilling enable commercial production from tight reservoirs, oil/gas recovery remains at a low level. Due to the technical and economic limitations of well-testing operations in tight reservoirs, rate-transient analysis (RTA has become a more attractive option. However, current RTA models hardly consider the effect of the non-uniform production on rate decline behaviors. In fact, PLT results demonstrate that production profile is non-uniform. To fill this gap, this paper presents an improved RTA model of multi-fractured horizontal wells (MFHWs to investigate the effects of non-uniform properties of hydraulic fractures (production of fractures, fracture half-length, number of fractures, fracture conductivity, and vertical permeability on rate transient behaviors through the diagnostic type curves. Results indicate obvious differences on the rate decline curves among the type curves of uniform properties of fractures (UPF and non-uniform properties of fractures (NPF. The use of dimensionless production integral derivative curve magnifies the differences so that we can diagnose the phenomenon of non-uniform production. Therefore, it’s significant to incorporate the effects of NPF into the RDA models of MFHWs, and the model proposed in this paper enables us to better evaluate well performance based on long-term production data.

Neglected, semimembranosus osteochondral avulsion fracture of the posteromedial tibial plateau

Directory of Open Access Journals (Sweden)

Rakesh John

2018-06-01

Full Text Available Semimembranosus avulsion fracture is infrequently reported and is easy to miss on plain radiographs; the mechanism of injury is highly controversial. Initial reports linked it to anterior cruciate ligament and medial meniscal tears. We report an osteochondral semimembranosus avulsion fracture of the posteromedial tibial plateau with associated posterior cruciate ligament rupture. Also described is a novel surgical fixation technique for such osteochondral fractures where the surgical exposure is limited due to the obliquity of the fracture line resulting in a greater involvement of the articular cartilage than the small bony component. The fixation technique described may be used for osteochondral fractures where the application of a conventional compression screw may not be feasible. Keywords: Osteochondral fracture, Semimembranosus avulsion fracture, Posteromedial tibial plateau, Neglected, Nonunion

Simulated evolution of fractures and fracture networks subject to thermal cooling: A coupled discrete element and heat conduction model

Energy Technology Data Exchange (ETDEWEB)

Huang, Hai; Plummer, Mitchell; Podgorney, Robert

2013-02-01

Advancement of EGS requires improved prediction of fracture development and growth during reservoir stimulation and long-term operation. This, in turn, requires better understanding of the dynamics of the strongly coupled thermo-hydro-mechanical (THM) processes within fractured rocks. We have developed a physically based rock deformation and fracture propagation simulator by using a quasi-static discrete element model (DEM) to model mechanical rock deformation and fracture propagation induced by thermal stress and fluid pressure changes. We also developed a network model to simulate fluid flow and heat transport in both fractures and porous rock. In this paper, we describe results of simulations in which the DEM model and network flow & heat transport model are coupled together to provide realistic simulation of the changes of apertures and permeability of fractures and fracture networks induced by thermal cooling and fluid pressure changes within fractures. Various processes, such as Stokes flow in low velocity pores, convection-dominated heat transport in fractures, heat exchange between fluid-filled fractures and solid rock, heat conduction through low-permeability matrices and associated mechanical deformations are all incorporated into the coupled model. The effects of confining stresses, developing thermal stress and injection pressure on the permeability evolution of fracture and fracture networks are systematically investigated. Results are summarized in terms of implications for the development and evolution of fracture distribution during hydrofracturing and thermal stimulation for EGS.

Age, Sex, and Dose Effects of Nonbenzodiazepine Hypnotics on Hip Fracture in Nursing Home Residents.

Science.gov (United States)

Dore, David D; Zullo, Andrew R; Mor, Vincent; Lee, Yoojin; Berry, Sarah D

2018-04-01

The Food and Drug Administration recommends a reduced dose of nonbenzodiazepine hypnotics in women, yet little is known about the age-, sex-, and dose-specific effects of these drugs on risk of hip fracture, especially among nursing home (NH) residents. We estimated the age-, sex-, and dose-specific effects of nonbenzodiazepine hypnotics on the rate of hip fracture among NH residents. Case-crossover study in US NHs. A total of 691 women and 179 men with hip fracture sampled from all US long-stay NH residents. Measures of patient characteristics were obtained from linked Medicare and the Minimum Data Set (2007-2008). The outcome was hospitalization for hip fracture with surgical repair. We estimated rate ratios (RRs) and 95% confidence intervals (CIs) from conditional logistic regression models for nonbenzodiazepine hypnotics (vs nonuse) comparing 0 to 29 days before hip fracture (hazard period) with 60 to 89 and 120 to 149 days before hip fracture (control periods). We stratified analyses by age, sex, and dose. The average RR of hip fracture was 1.7 (95% CI 1.5-1.9) for any use. The RR of hip fracture was higher for residents aged ≥90 years vs <70 years (2.2 vs 1.3); however, the CIs overlapped. No differences in the effect of the hypnotic on risk of hip fracture were evident by sex. Point estimates for hip fracture were greater with high-dose versus low-dose hypnotics (RR 1.9 vs 1.6 for any use), but these differences were highly compatible with chance. The rate of hip fracture in NH residents due to use of nonbenzodiazepine hypnotics was greater among older patients than among younger patients and, possibly, with higher doses than with lower doses. When clinicians are prescribing a nonbenzodiazepine hypnotic to any NH resident, doses of these drugs should be kept as low as possible, especially among those with advanced age. Copyright © 2017 AMDA – The Society for Post-Acute and Long-Term Care Medicine. Published by Elsevier Inc. All rights reserved.

Radiographically Occult and Subtle Fractures: A Pictorial Review

International Nuclear Information System (INIS)

Jarraya, M.; Hayashi, D.; Roemer, F.W.; Crema, M.D.; Conlin, J.; Marra, M.D.; Guermazi, A.; Roemer, F.W.; Crema, M.D.; Diaz, L.; Conlin, J.; Jomaah, N.

2013-01-01

Radiographically occult and subtle fractures are a diagnostic challenge. They may be divided into (1) high energy trauma fracture, (2) fatigue fracture from cyclical and sustained mechanical stress, and (3) insufficiency fracture occurring in weakened bone (e.g., in osteoporosis and post radiotherapy). Independently of the cause, the initial radiographic examination can be negative either because the findings seem normal or are too subtle. Early detection of these fractures is crucial to explain the patients symptoms and prevent further complications. Advanced imaging tools such as computed tomography, magnetic resonance imaging, and scintigraphy are highly valuable in this context. Our aim is to raise the awareness of radiologists and clinicians in these cases by presenting illustrative cases and a discussion of the relevant literature.

Intelligent fracture creation for shale gas development

KAUST Repository

Douglas, Craig C.

2011-05-14

Shale gas represents a major fraction of the proven reserves of natural gas in the United States and a collection of other countries. Higher gas prices and the need for cleaner fuels provides motivation for commercializing shale gas deposits even though the cost is substantially higher than traditional gas deposits. Recent advances in horizontal drilling and multistage hydraulic fracturing, which dramatically lower costs of developing shale gas fields, are key to renewed interest in shale gas deposits. Hydraulically induced fractures are quite complex in shale gas reservoirs. Massive, multistage, multiple cluster treatments lead to fractures that interact with existing fractures (whether natural or induced earlier). A dynamic approach to the fracturing process so that the resulting network of reservoirs is known during the drilling and fracturing process is economically enticing. The process needs to be automatic and done in faster than real-time in order to be useful to the drilling crews.

Complications of hip fractures: A review

Science.gov (United States)

Carpintero, Pedro; Caeiro, Jose Ramón; Carpintero, Rocío; Morales, Angela; Silva, Samuel; Mesa, Manuel

2014-01-01

Nowadays, fracture surgery represents a big part of the orthopedic surgeon workload, and usually has associated major clinical and social cost implications. These fractures have several complications. Some of these are medical, and other related to the surgical treatment itself. Medical complications may affect around 20% of patients with hip fracture. Cognitive and neurological alterations, cardiopulmonary affections (alone or combined), venous thromboembolism, gastrointestinal tract bleeding, urinary tract complications, perioperative anemia, electrolytic and metabolic disorders, and pressure scars are the most important medical complications after hip surgery in terms of frequency, increase of length of stay and perioperative mortality. Complications arising from hip fracture surgery are fairly common, and vary depending on whether the fracture is intracapsular or extracapsular. The main problems in intracapsular fractures are biological: vascularization of the femoral head, and lack of periosteum -a major contributor to fracture healing- in the femoral neck. In extracapsular fractures, by contrast, the problem is mechanical, and relates to load-bearing. Early surgical fixation, the role of anti-thromboembolic and anti-infective prophylaxis, good pain control at the perioperative, detection and management of delirium, correct urinary tract management, avoidance of malnutrition, vitamin D supplementation, osteoporosis treatment and advancement of early mobilization to improve functional recovery and falls prevention are basic recommendations for an optimal maintenance of hip fractured patients. PMID:25232517

Fracture of the Atlas through a Synchondrosis of Anterior Arch

Directory of Open Access Journals (Sweden)

Gamze Turk

2013-01-01

Full Text Available Cervical fractures are rare in paediatric population. In younger children, cervical fractures usually occur above the level of C4; whereas in older population, fractures or dislocations more commonly involve the lower cervical spine. Greater elasticity of intervertebral ligaments and also the spinal vertebrae explains why cervical fractures in paediatric ages are rare. The injury usually results from a symmetric or asymmetric axial loading. In paediatric cases, most fractures occur through the synchondroses which are the weakest links of the atlas. The prognosis depends on the severity of the spinal cord injury. In this case, we presented an anterior fracture in synchondrosis of atlas after falling on head treated with cervical collar. There was no neurologic deficit for the following 2 years.

Tuning Fractures With Dynamic Data

Science.gov (United States)

Yao, Mengbi; Chang, Haibin; Li, Xiang; Zhang, Dongxiao

2018-02-01

Flow in fractured porous media is crucial for production of oil/gas reservoirs and exploitation of geothermal energy. Flow behaviors in such media are mainly dictated by the distribution of fractures. Measuring and inferring the distribution of fractures is subject to large uncertainty, which, in turn, leads to great uncertainty in the prediction of flow behaviors. Inverse modeling with dynamic data may assist to constrain fracture distributions, thus reducing the uncertainty of flow prediction. However, inverse modeling for flow in fractured reservoirs is challenging, owing to the discrete and non-Gaussian distribution of fractures, as well as strong nonlinearity in the relationship between flow responses and model parameters. In this work, building upon a series of recent advances, an inverse modeling approach is proposed to efficiently update the flow model to match the dynamic data while retaining geological realism in the distribution of fractures. In the approach, the Hough-transform method is employed to parameterize non-Gaussian fracture fields with continuous parameter fields, thus rendering desirable properties required by many inverse modeling methods. In addition, a recently developed forward simulation method, the embedded discrete fracture method (EDFM), is utilized to model the fractures. The EDFM maintains computational efficiency while preserving the ability to capture the geometrical details of fractures because the matrix is discretized as structured grid, while the fractures being handled as planes are inserted into the matrix grids. The combination of Hough representation of fractures with the EDFM makes it possible to tune the fractures (through updating their existence, location, orientation, length, and other properties) without requiring either unstructured grids or regridding during updating. Such a treatment is amenable to numerous inverse modeling approaches, such as the iterative inverse modeling method employed in this study, which is

Splinting of Longitudinal Fracture: An Innovative Approach

Directory of Open Access Journals (Sweden)

Rashmi Bansal

2016-01-01

Full Text Available Trauma may result in craze lines on the enamel surface, one or more fractured cusps of posterior teeth, cracked tooth syndrome, splitting of posterior teeth, and vertical fracture of root. Out of these, management of some fractures is of great challenge and such teeth are generally recommended for extraction. Literature search reveals attempts to manage such fractures by full cast crown, orthodontic wires, and so forth, in which consideration was given to extracoronal splinting only. However, due to advancement in materials and technologies, intracoronal splinting can be achieved as well. In this case report, longitudinal fractures in tooth #27, tooth #37, and tooth #46 had occurred. In #27, fracture line was running mesiodistally involving the pulpal floor resulting in a split tooth. In teeth 37 and 46, fractures of the mesiobuccal cusp and mesiolingual cusp were observed, respectively. They were restored with cast gold inlay and full cast crown, respectively. Longitudinal fracture of 27 was treated with an innovative approach using intracanal reinforced composite with Ribbond, external reinforcement with an orthodontic band, and full cast metal crown to splint the split tooth.

Fracture behavior of human molars.

Science.gov (United States)

Keown, Amanda J; Lee, James J-W; Bush, Mark B

2012-12-01

Despite the durability of human teeth, which are able to withstand repeated loading while maintaining form and function, they are still susceptible to fracture. We focus here on longitudinal fracture in molar teeth-channel-like cracks that run along the enamel sidewall of the tooth between the gum line (cemento-enamel junction-CEJ) and the occlusal surface. Such fractures can often be painful and necessitate costly restorative work. The following study describes fracture experiments made on molar teeth of humans in which the molars are placed under axial compressive load using a hard indenting plate in order to induce longitudinal cracks in the enamel. Observed damage modes include fractures originating in the occlusal region ('radial-median cracks') and fractures emanating from the margin of the enamel in the region of the CEJ ('margin cracks'), as well as 'spalling' of enamel (the linking of longitudinal cracks). The loading conditions that govern fracture behavior in enamel are reported and observations made of the evolution of fracture as the load is increased. Relatively low loads were required to induce observable crack initiation-approximately 100 N for radial-median cracks and 200 N for margin cracks-both of which are less than the reported maximum biting force on a single molar tooth of several hundred Newtons. Unstable crack growth was observed to take place soon after and occurred at loads lower than those calculated by the current fracture models. Multiple cracks were observed on a single cusp, their interactions influencing crack growth behavior. The majority of the teeth tested in this study were noted to exhibit margin cracks prior to compression testing, which were apparently formed during the functional lifetime of the tooth. Such teeth were still able to withstand additional loading prior to catastrophic fracture, highlighting the remarkable damage containment capabilities of the natural tooth structure.

Anomalous Transport in Natural Fracture Networks Induced by Tectonic Stress

Science.gov (United States)

Kang, P. K.; Lei, Q.; Lee, S.; Dentz, M.; Juanes, R.

2017-12-01

Fluid flow and transport in fractured rock controls many natural and engineered processes in the subsurface. However, characterizing flow and transport through fractured media is challenging due to the high uncertainty and large heterogeneity associated with fractured rock properties. In addition to these "static" challenges, geologic fractures are always under significant overburden stress, and changes in the stress state can lead to changes in the fracture's ability to conduct fluids. While confining stress has been shown to impact fluid flow through fractures in a fundamental way, the impact of confining stress on transportthrough fractured rock remains poorly understood. The link between anomalous (non-Fickian) transport and confining stress has been shown, only recently, at the level of a single rough fracture [1]. Here, we investigate the impact of geologic (tectonic) stress on flow and tracer transport through natural fracture networks. We model geomechanical effects in 2D fractured rock by means of a finite-discrete element method (FEMDEM) [2], which can capture the deformation of matrix blocks, reactivation of pre-existing fractures, and propagation of new cracks, upon changes in the stress field. We apply the model to a fracture network extracted from the geological map of an actual rock outcrop to obtain the aperture field at different stress conditions. We then simulate fluid flow and particle transport through the stressed fracture networks. We observe that anomalous transport emerges in response to confining stress on the fracture network, and show that the stress state is a powerful determinant of transport behavior: (1) An anisotropic stress state induces preferential flow paths through shear dilation; (2) An increase in geologic stress increases aperture heterogeneity that induces late-time tailing of particle breakthrough curves. Finally, we develop an effective transport model that captures the anomalous transport through the stressed fracture

Graphene Foam: Uniaxial Tension Behavior and Fracture Mode Based on a Mesoscopic Model.

Science.gov (United States)

Pan, Douxing; Wang, Chao; Wang, Tzu-Chiang; Yao, Yugui

2017-09-26

Because of the combined advantages of both porous materials and two-dimensional (2D) graphene sheets, superior mechanical properties of three-dimensional (3D) graphene foams have received much attention from material scientists and energy engineers. Here, a 2D mesoscopic graphene model (Modell. Simul. Mater. Sci. Eng. 2011, 19, 054003), was expanded into a 3D bonded graphene foam system by utilizing physical cross-links and van der Waals forces acting among different mesoscopic graphene flakes by considering the debonding behavior, to evaluate the uniaxial tension behavior and fracture mode based on in situ SEM tensile testing (Carbon 2015, 85, 299). We reasonably reproduced a multipeak stress-strain relationship including its obvious yielding plateau and a ductile fracture mode near 45° plane from the tensile direction including the corresponding fracture morphology. Then, a power scaling law of tensile elastic modulus with mass density and an anisotropic strain-dependent Poisson's ratio were both deduced. The mesoscopic physical mechanism of tensile deformation was clearly revealed through the local stress state and evolution of mesostructure. The fracture feature of bonded graphene foam and its thermodynamic state were directly navigated to the tearing pattern of mesoscopic graphene flakes. This study provides an effective way to understand the mesoscopic physical nature of 3D graphene foams, and hence it may contribute to the multiscale computations of micro/meso/macromechanical performances and optimal design of advanced graphene-foam-based materials.

Some advances in fracture studies under the heavy-section steel technology program

International Nuclear Information System (INIS)

Pugh, C.E.; Corwin, W.R.; Bryan, R.H.; Bass, B.R.

1985-01-01

Recent results are summarized from HSST studies in three major areas that relate to assessing nuclear reactor pressure vessel integrity under pressurized-thermal-shock (PTS) conditions: irradiation effects on the fracture properties of stainless steel cladding, crack run-arrest behavior under nonisothermal conditions, and fracture behavior of a thick-wall vessel under combined thermal and pressure loadings

The cardiorenal link in advanced cirrhosis

DEFF Research Database (Denmark)

Krag, Aleksander; Bendtsen, Flemming; Burroughs, Andrew K

2012-01-01

A considerable number of patients with advanced cirrhosis develop a hepatorenal syndrome. The pathogenesis involves liver dysfunction, splanchnic vasodilatation, and activation of vasoconstrictive systems. There are now several observations that indicate a relation between the renal failure...... and impaired cardiac function in patients with advanced cirrhosis. Cirrhotic cardiomyopathy has been described as a condition with impaired contractile responsiveness to stress and altered diastolic relaxation. We propose a cardiorenal interaction in patients with advanced cirrhosis and renal dysfunction...

Diagnosing displaced four-part fractures of the proximal humerus

DEFF Research Database (Denmark)

Brorson, Stig; Bagger, Jens; Sylvest, Annette

2009-01-01

Displaced four-part fractures comprise 2-10 % of all proximal humeral fractures. The optimal treatment is unclear and randomised trials are needed. The conduct and interpretation of such trials is facilitated by a reproducible fracture classification. We aimed at quantifying observer agreement...... on the classification of displaced four-part fractures according to the Neer system. Published and unpublished data from five observer studies were reviewed. Observers agreed less on displaced four-part fractures than on the overall Neer classification. Mean kappa values for interobserver agreement ranged from 0.......16 to 0.48. Specialists agreed slightly more than fellows and residents. Advanced imaging modalities (CT and 3D CT) seemed to contribute more to classification of displaced four-part patterns than in less complex fracture patterns. Low observer agreement may challenge the clinical approach to displaced...

Introduction into technical application of fracture mechanics. 3. rev. ed.

International Nuclear Information System (INIS)

Heckel, K.

1991-01-01

Technical components made out of metal material are liable to be defective. Cracks are the most dangerous defects. Based on fracture mechanics methods were developed which permit to estimate the proveness of cracks to intrate fracture. The present book is restricted to the standardised methods of fracture mechanics. Theoretical foundations of various concepts aspect under the fracture mechanics are given. Experimental methods of determining material characteristics of fracture mechanics are explained in detail as a profound knowledge of testing criteria is necessary in order to be able to a characteristic to a component. This book contains the latest level of standardised methods of fracture mechanics. It is meant for advanced students and engineers working in practice. Some fully calculated examples are used as an introduction into the thinking of fracture mechanics. (orig./MM) [de

Stochastic and fractal analysis of fracture trajectories

Science.gov (United States)

Bessendorf, Michael H.

1987-01-01

Analyses of fracture trajectories are used to investigate structures that fall between 'micro' and 'macro' scales. It was shown that fracture trajectories belong to the class of nonstationary processes. It was also found that correlation distance, which may be related to a characteristic size of a fracture process, increases with crack length. An assemblage of crack trajectory processes may be considered as a diffusive process. Chudnovsky (1981-1985) introduced a 'crack diffusion coefficient' d which reflects the ability of the material to deviate the crack trajectory from the most energetically efficient path and thus links the material toughness to its structure. For the set of fracture trajectories in AISI 304 steel, d was found to be equal to 1.04 microns. The fractal dimension D for the same set of trajectories was found to be 1.133.

Hemiarthroplasty for proximal humeral fracture: restoration of the Gothic arch.

Science.gov (United States)

Krishnan, Sumant G; Bennion, Phillip W; Reineck, John R; Burkhead, Wayne Z

2008-10-01

Proximal humerus fractures are the most common fractures of the shoulder girdle, and initial management of these injuries often determines final outcome. When arthroplasty is used to manage proximal humeral fractures, surgery remains technically demanding, and outcomes have been unpredictable. Recent advances in both technique and prosthetic implants have led to more successful and reproducible results. Key technical points include restoration of the Gothic arch, anatomic tuberosity reconstruction, and minimal soft tissue dissection.

Fracture mechanics

International Nuclear Information System (INIS)

Miannay, D.P.

1995-01-01

This book entitle ''Fracture Mechanics'', the first one of the monograph ''Materiologie'' is geared to design engineers, material engineers, non destructive inspectors and safety experts. This book covers fracture mechanics in isotropic homogeneous continuum. Only the monotonic static loading is considered. This book intended to be a reference with the current state of the art gives the fundamental of the issues under concern and avoids the developments too complicated or not yet mastered for not making reading cumbersome. The subject matter is organized as going from an easy to a more complicated level and thus follows the chronological evolution in the field. Similarly the microscopic scale is considered before the macroscopic scale, the physical understanding of phenomena linked to the experimental observation of the material preceded the understanding of the macroscopic behaviour of structures. In this latter field the relatively recent contribution of finite element computations with some analogy with the experimental observation is determining. However more sensitive analysis is not skipped

Adherence to a Mediterranean diet and risk of fractures in French older persons.

OpenAIRE

Feart , Catherine; Lorrain , Simon; Ginder Coupez , Vanessa; Samieri , Cécilia; Letenneur , Luc; Paineau , Damien; Barberger-Gateau , Pascale

2013-01-01

International audience; UNLABELLED: Prevention of fractures is a considerable public health challenge. In a population-based cohort of French elderly people, a diet closer to a Mediterranean type had a borderline significant deleterious effect on the risk of fractures, in part linked to a low consumption of dairy products and a high consumption of fruits. INTRODUCTION: Higher adherence to the Mediterranean diet (MeDi) is linked to a lower risk of several chronic diseases, but its association ...

Approaching a universal scaling relationship between fracture stiffness and fluid flow

Science.gov (United States)

Pyrak-Nolte, Laura J.; Nolte, David D.

2016-02-01

A goal of subsurface geophysical monitoring is the detection and characterization of fracture alterations that affect the hydraulic integrity of a site. Achievement of this goal requires a link between the mechanical and hydraulic properties of a fracture. Here we present a scaling relationship between fluid flow and fracture-specific stiffness that approaches universality. Fracture-specific stiffness is a mechanical property dependent on fracture geometry that can be monitored remotely using seismic techniques. A Monte Carlo numerical approach demonstrates that a scaling relationship exists between flow and stiffness for fractures with strongly correlated aperture distributions, and continues to hold for fractures deformed by applied stress and by chemical erosion as well. This new scaling relationship provides a foundation for simulating changes in fracture behaviour as a function of stress or depth in the Earth and will aid risk assessment of the hydraulic integrity of subsurface sites.

Tomosynthesis: A new radiologic technique for rapid diagnosis of scaphoid fractures.

Science.gov (United States)

Compton, N; Murphy, L; Lyons, F; Jones, J; MacMahon, P; Cashman, J

2016-12-21

Scaphoid fractures constitute 71% of all carpal bone fractures. 1 Early diagnosis and treatment has significant bearing on fracture union rates and better clinical outcomes. While displaced fractures can be readily seen on plain radiograph, undisplaced fractures can require advanced imaging modalities to confirm that diagnosis. Advanced imaging such as Magnetic Resonance Imaging (MRI), Computerised tomography (CT) and bone scintigraphy are routinely used for the diagnosis of scaphoid fractures but require significant radiation exposure, increased cost and can be difficult to access. 2 Tomosynthesis is an emerging imaging modality which uses conventional x-ray systems to produce cross-sectional images. There has yet to be extensive research carried out investigating the diagnostic value of tomosynthesis in scaphoid fractures. The aim of this study is to optimise patient positioning for the diagnosis of scaphoid fractures in a cadaveric model and compare the diagnostic yield of tomography to conventional CT. Using four cadaveric specimens, three limb positions were examined in unfractured and fractured scaphoids to determine the optimal limb positions required for visualisation of the scaphoid. As a result of this study, the optimal position for visualisation of the scaphoid and diagnosis of scaphoid fractures has been determined. The results demonstrate that tomosynthesis is as effective as CT scanning in identifying scaphoid fractures in both sensitivity and specificity. By comparison to CT, tomosynthesis is cheaper, has lower radiation exposure, requires fewer hospital resources and can be performed quickly. Tomosynthesis is a valid diagnostic tool for the diagnosis of scaphoid fractures. Copyright © 2016 Royal College of Surgeons of Edinburgh (Scottish charity number SC005317) and Royal College of Surgeons in Ireland. Published by Elsevier Ltd. All rights reserved.

Contaminant transport in fractured porous media: analytical solution for a two-member decay chain in a single fracture

International Nuclear Information System (INIS)

Sudicky, E.A.; Frind, E.O.

1984-01-01

An analytical solution is presented for the problem of radionuclide chain decay during transport through a discrete fracture situated in a porous rock matrix. The solution takes into account advection along the fracture, molecular diffusion from the fracture to the porous matrix, adsorption on the fracture face, adsorption in the rock matrix, and radioactive decay. The solution for the daughter product is in the form of a double integral which is evaluated by Gauss-Legendre quadrature. Results show that the daughter product tends to advance ahead of the parent nuclide even when the half-life of the parent is larger. This is attributed to the effect of chain decay in the matrix, which tends to reduce the diffusive loss of the daughter along the fracture. The examples also demonstrate that neglecting the parent nuclide and modeling its daughter as a single species can result in significant overestimation of arrival times at some point along the fracture. Although the analytical solution is restricted to a two-member chain for practical reasons, it represents a more realistic description of nuclide transport along a fracture than available single-species models. The solution may be of use for application to other contaminants undergoing different types of first-order transformation reactions

Advanced technologies for encryption of satellite links

Science.gov (United States)

McMahan, Sherry S.

The use of encryption on satellite links is discussed. Advanced technology exists to provide transmission security for large earth station with data rates up to 50 megabits per second. One of the major concerns in the use of encryption equipment with very small aperture terminals (VSAT) is the key management issue and the related operational costs. The low cost requirement and the lack of physical protection of remote VSATs place severe constraints on the design of encryption equipment. Encryption may be accomplished by embedding a tamper proof encryption module into the baseband unit of each VSAT. VSAT networks are usually star networks where there is a single large earth station that serves as a hub and all satellite communications takes place between each VSAT and the hub earth station. The hub earth station has the secret master key of each VSAT. These master keys are used to downline load encrypted session keys to each VSAT. A more secure alternative is to use public key techniques where each embedded VSAT encryption module internally generates its own secret and public numbers. The secret number never leaves the module while the public number is sent to the hub at the time of initialization of the encryption module into the VSAT. Physical access control to encryption modules of VSAT systems can be implemented using passwords, smart cards or biometrics.

Relationship between vitamin D, osteoporotic fracture and falls.

Science.gov (United States)

Candel Romero, Carmen; Forner Cordero, Ángeles; Sánchez Santos, José Cristóbal; Pereiró Berenguer, Inmaculada

2017-11-22

Link low levels of vitamin D, osteoporotic fracture and falls. Transversal observational study with the study variables of age, levels of vitamin D, osteoporotic fracture and falls. The study population was patients evaluated by the Rehabilitation Department, Hospital of Sagunto, from January 2013 to December 2014. Of the 242 patients who underwent vitamin D analysis, 70.6% showed levels under 30ng/ml. Forty-eight percent of the patients with below normal levels of vitamin D suffered a fracture, opposed to 32.4% patients with normal levels. Thus, controlling by age, patients with low levels of vitamin D are 4.8 times more likely to suffer a fracture than those with normal levels. Regarding falls, controlling by age, there is a higher risk of falling (adjusted OR 2.68) in those patients with low levels of vitamin D. Patients with low vitamin D levels are more likely to suffer falls and fractures. Copyright © 2017 Elsevier España, S.L.U. All rights reserved.

Rib fractures in blunt chest trauma - associated thoracic injuries

Directory of Open Access Journals (Sweden)

Iv. Dimitrov

2017-09-01

Full Text Available PURPOSE. The aim of our retrospective study was to analyze the patterns of associated thoracic injuries in patients underwent blunt chest trauma and rib fractures. METHODS. The study included 212 patients with rib fractures due to blunt thoracic trauma. The mechanism of trauma, the type of rib fracture and the type of associated injuries were analyzed. RESULTS. The patients were divided in two groups according to the number of fractured ribs-group I included the patients with up to two fractured ribs (72 patients-33,9%, and group II – with ≥3 fractured ribs (140 patients-66,1%. Associated chest injuries were present in 36 of the patients from group I (50%, and in 133 patients from group II (95%. Pulmonary contusion was the most common intrathoracicinjurie-65,6% of the cases. The mean hospital stay was 8, 7 days. The lethality rate was 16,9% -all of them due to the associated chest injuries. CONCLUSIONS. The mortality related to rib fractures is affected by the associated thoracic injuries, the advanced age, and the number of fractured ribs.

Scaphoid Fracture Fixation with an Acutrak? Screw

OpenAIRE

Loving, Vilert A.; Richardson, Michael L.

2015-01-01

We report a case of fixation of a scaphoid fracture using an Acutrak? screw. This screw is cannulated and headless, which allows it to be implanted below the surface of the bone. It uses the same concept of variable thread pitch as the Herbert screw, but unlike the Herbert screw, is fully threaded, with continuously varying pitch along its length. This variable pitch creates constant compression across a fracture as the screw is advanced, and gives the screw its unique appearance. This featur...

Hyponatremia, a risk factor for osteoporosis and fractures in women

DEFF Research Database (Denmark)

Holm, J P; Amar, A O S; Hyldstrup, L

2016-01-01

Hyponatremia has been linked to an increased risk of osteoporosis and fractures. We found an increased hazard ratio of major osteoporotic fractures adjusted for potential confounders, including osteoporosis and medication. A reduced BMD was not sufficiently explaining the association. Our data...... indicate that hyponatremia should be considered a risk factor for osteoporosis and fractures. INTRODUCTION: Hyponatremia is the most common electrolyte disorder in clinical practice and could be a risk factor for both osteoporosis and fractures. Mild hyponatremia has traditionally been regarded as a benign...... and asymptomatic condition; however, data from large population and animal studies have led to a reappraisal of this view. The purpose of this study was to evaluate the association of hyponatremia with osteoporosis and major osteoporotic fractures (MOF) in women. METHODS: This is a historical cohort study...

Risk factors for trochanteric and femoral neck fracture.

Science.gov (United States)

Díaz, A R; Navas, P Z

The differences between the two main types of fracture of proximal end of the femur, trochanteric and cervical fractures, are still a subject of study, and could be the key to a better understanding of its pathophysiology and prevention. The aim of this study is to determine whether epidemiological differences in the distribution of risk factors associated with hip fracture exist between these two entities. A descriptive cross-sectional study of 428 patients over the age of 65 admitted for trochanteric or cervical fractures in 2015, in which gender, age, previous diagnosis, external causes associated with fracture and place of the event were recorded. There were 220 patients with a cervical fracture (51.4%) and 208 patients with a trochanteric fracture (48.6%). The average age was higher in the trochanteric fracture, observing a constant increase with age only in women with trochanteric fractures. Cervical fracture showed a significant association with cerebrovascular disease (p=0.039) and trochanteric fracture with accidental falls (p=0.047) and presence of 5-9 previous diseases (p=0.014). A regression analysis maintained this association in the case of a cerebrovascular disease (OR 2.6, 95%CI 1.1-6.4) and the presence of 5-9 diseases (OR 1.5, 95%CI 1.1-2.3). Trochanteric fractures are associated with women patients of more advanced ages, 5-9 previous diseases and accidental falls. Cerebrovascular disease shows a higher prevalence in cervical fractures. Copyright © 2017 SECOT. Publicado por Elsevier España, S.L.U. All rights reserved.

Anchorage strategies in geriatric hip fracture management

Directory of Open Access Journals (Sweden)

Knobe Matthias

2016-12-01

Full Text Available There is an enormous humanitarian and socioeconomic need to improve the quality and effectiveness of care for patients with hip fracture. To reduce mechanical complications in the osteosynthesis of proximal femoral fractures, improved fixation techniques have been developed including blade or screw-anchor devices, locked minimally invasive or cement augmentation strategies. However, despite numerous innovations and advances regarding implant design and surgical techniques, systemic and mechanical complication rates remain high. Treatment success depends on secure implant fixation in often-osteoporotic bone as well as on patient-specific factors (fracture stability, bone quality, comorbidity, and gender and surgeon-related factors (experience, correct reduction, and optimal screw placement in the head/neck fragment. For fracture fixation, the anchorage of the lag screw within the femoral head plays a crucial role depending on the implant’s design. Meta-analyses and randomized controlled studies demonstrate that there is a strong trend towards arthroplasty treating geriatric femoral neck fractures. However, for young adults as well as older patients with less compromised bone quality, or in undisplaced fractures, head-preserving therapy is preferred as it is less invasive and associated with good functional results. This review summarizes the evidence for the internal fixation of femoral neck fractures and trochanteric femoral fractures in elderly patients. In addition, biomechanical considerations regarding implant anchorage in the femoral head including rotation, migration, and femoral neck shortening are made. Finally, cement augmentation strategies for hip fracture implants are evaluated critically.

Heavy-Section Steel Technology program fracture issues

International Nuclear Information System (INIS)

Pennell, W.E.

1989-10-01

Large scale fracture mechanics tests have resulted in the identification of a number of fracture technology issues. Identification of additional issues has come from the reactor vessel materials irradiation test program and from reactor operating experience. This paper provides a review of fracture issues with an emphasis on their potential impact on a reactor vessel pressurized thermal shock (PTS) analysis. Mixed mode crack propagation emerges as a major issue, due in large measure to the poor performance of existing models for the prediction of ductile tearing. Rectification of ductile tearing technology deficiencies may require extending the technology to include a more complete treatment of stress state and loading history effects. The effect of cladding on vessel fracture remains uncertain to the point that it is not possible to determine at this time if the net effect will be positive or negative. Enhanced fracture toughness for shallow flaws has been demonstrated for low strength structural steels. Demonstration of a similar effect in reactor pressure vessel steels could have a significant beneficial effect on the probabilistic analysis of reactor vessel fracture. Further development of existing fracture mechanics models and concepts is required to meet the special requirements for fracture evaluation of circumferential flaws in the welds of ring forged vessels. Fracture technology advances required to address the issues discussed in this paper are the major objective for the ongoing Heavy Section Steel Technology (HSST) program at ORNL. 24 refs., 18 figs

Heavy-section steel technology program: Fracture issues

International Nuclear Information System (INIS)

Pennell, W.E.

1992-01-01

Large-scale fracture mechanics tests have resulted in the identification of a number of fracture technology issues. Identification of additional issues has come from the reactor vessel materials irradiation test program and from reactor operating experience. This paper provides a review of fracture issues with an emphasis on their potential impact on a reactor vessel pressurized thermal shock (PTS) analysis. Mixed mode crack propagation emerges as a major issue, due in large measure to the poor performance of existing models for the prediction of ductile tearing. Rectification of ductile tearing technology deficiencies may require extending the technology to include a more complete treatment of stress state and loading history effects. The effect of cladding on vessel fracture remains uncertain to the point that it is not possible to determine at this time if the net effect will be positive or negative. Enhanced fracture toughness for shallow flaws has been demonstrated for low-strength structural steels. Demonstration of a similar effect in reactor pressure vessel steels could have a significant beneficial effect on the probabilistic analysis of reactor vessel fracture. Further development of existing fracture mechanics models and concepts is required to meet the special requirements for fracture evaluation of circumferential flaws in the welds of ring-forged vessels. Fracture technology advances required to address the issues discussed in this paper are the major objective for the ongoing Heavy Section Steel Technology (HSST) program at ORNL

The Vienna LTE-advanced simulators up and downlink, link and system level simulation

CERN Document Server

Rupp, Markus; Taranetz, Martin

2016-01-01

This book introduces the Vienna Simulator Suite for 3rd-Generation Partnership Project (3GPP)-compatible Long Term Evolution-Advanced (LTE-A) simulators and presents applications to demonstrate their uses for describing, designing, and optimizing wireless cellular LTE-A networks. Part One addresses LTE and LTE-A link level techniques. As there has been high demand for the downlink (DL) simulator, it constitutes the central focus of the majority of the chapters. This part of the book reports on relevant highlights, including single-user (SU), multi-user (MU) and single-input-single-output (SISO) as well as multiple-input-multiple-output (MIMO) transmissions. Furthermore, it summarizes the optimal pilot pattern for high-speed communications as well as different synchronization issues. One chapter is devoted to experiments that show how the link level simulator can provide input to a testbed. This section also uses measurements to present and validate fundamental results on orthogonal frequency division multiple...

CURBSIDE CONSULTATION IN FRACTURE MANAGEMENT: 49 CLINICAL QUESTIONS

Directory of Open Access Journals (Sweden)

Walter W. Virkus

2008-12-01

displaced bimalleolar fracture in insulin dependant middle aged woman; Man-agement of calcaneal fractures; Fixation technic for a displaced talar neck fracture in a patient in ER; Indica-tions for surgical treatment of metatarsal fractures; Bone grafting in acute fractures; Management of a nonunion of plated midshaft tibia fracture; Management of a child with a twisted ankle and normal x-rays; Assessment of com-partment syndrome in foot.The Section III is about “GENERAL FRACTURE CARE” including: Management of multiple orthopedic injuries and damage control orthopedics; Bone stimula-tion in nonunion; Indications for locking plates; Fractures requiring anatomic reduction.AUDIENCE: Mainly trauma fellows and practicing or-thopedists are the targeted audience of the book, but not only the basic knowledge for the orthopedic residents but also the expert advices for complicated and controversial cases pointing experienced surgeons widen the spectrum of audience. Also non-physician personnel may benefit the basic knowledge from brief answers given in a casual format.ASSESMENT: “Curbside Consultation in Fracture Man-agement:49 Clinical Questions” offering practical, brief, evidence based answers to frequently asked questions especially those have been often left controversial related with the treatment of fractures of upper and lower extrem-ity, pelvic fractures is a useful resource mainly for resi-dents, fellows and junior orthopedists. Casual format that mimics a “curbside” dialog of colleagues and also the rich illustrations by images and diagrams makes the advanced knowledge in the text easier to understand and learn. Questions are carefully chosen from a wide spectrum of subjects related to fracture management to form a unique reference including high and low energy trauma fractures, pediatric fractures, fractures in elderly, multiple orthope-dic injury, and general fracture care. Assessment of frac-tures and diagnostic approach, postoperative care and

Characterization of reservoir fractures using conventional geophysical logging

Directory of Open Access Journals (Sweden)

Paitoon Laongsakul

2011-04-01

Full Text Available In hydrocarbon exploration fractures play an important role as possible pathways for the hydrocarbon flow and bythis enhancing the overall formation’s permeability. Advanced logging methods for fracture analysis, like the boreholeacoustic televiewer and Formation Microscanner (FMS are available, but these are additional and expensive tools. However,open and with water or hydrocarbon filled fractures are also sensitive to electrical and other conventional logging methods.For this study conventional logging data (electric, seismic, etc were available plus additional fracture information from FMS.Taking into account the borehole environment the results show that the micro-spherically focused log indicates fractures byshowing low resistivity spikes opposite open fractures, and high resistivity spikes opposite sealed ones. Compressional andshear wave velocities are reduced when passing trough the fracture zone, which are assumed to be more or less perpendicularto borehole axis. The photoelectric absorption curve exhibit a very sharp peak in front of a fracture filled with bariteloaded mud cake. The density log shows low density spikes that are not seen by the neutron log, usually where fractures,large vugs, or caverns exist. Borehole breakouts can cause a similar effect on the logging response than fractures, but fracturesare often present when this occurs. The fracture index calculation by using threshold and input weight was calculatedand there was in general a good agreement with the fracture data from FMS especially in fracture zones, which mainlycontribute to the hydraulic system of the reservoir. Finally, the overall results from this study using one well are promising,however further research in the combination of different tools for fracture identification is recommended as well as the useof core for further validation.

Hydraulic Fracturing: Paving the Way for a Sustainable Future?

Directory of Open Access Journals (Sweden)

Jiangang Chen

2014-01-01

Full Text Available With the introduction of hydraulic fracturing technology, the United States has become the largest natural gas producer in the world with a substantial portion of the production coming from shale plays. In this review, we examined current hydraulic fracturing literature including associated wastewater management on quantity and quality of groundwater. We conclude that proper documentation/reporting systems for wastewater discharge and spills need to be enforced at the federal, state, and industrial level. Furthermore, Underground Injection Control (UIC requirements under SDWA should be extended to hydraulic fracturing operations regardless if diesel fuel is used as a fracturing fluid or not. One of the biggest barriers that hinder the advancement of our knowledge on the hydraulic fracturing process is the lack of transparency of chemicals used in the practice. Federal laws mandating hydraulic companies to disclose fracturing fluid composition and concentration not only to federal and state regulatory agencies but also to health care professionals would encourage this practice. The full disclosure of fracturing chemicals will allow future research to fill knowledge gaps for a better understanding of the impacts of hydraulic fracturing on human health and the environment.

Hydraulic fracturing: paving the way for a sustainable future?

Science.gov (United States)

Chen, Jiangang; Al-Wadei, Mohammed H; Kennedy, Rebekah C M; Terry, Paul D

2014-01-01

With the introduction of hydraulic fracturing technology, the United States has become the largest natural gas producer in the world with a substantial portion of the production coming from shale plays. In this review, we examined current hydraulic fracturing literature including associated wastewater management on quantity and quality of groundwater. We conclude that proper documentation/reporting systems for wastewater discharge and spills need to be enforced at the federal, state, and industrial level. Furthermore, Underground Injection Control (UIC) requirements under SDWA should be extended to hydraulic fracturing operations regardless if diesel fuel is used as a fracturing fluid or not. One of the biggest barriers that hinder the advancement of our knowledge on the hydraulic fracturing process is the lack of transparency of chemicals used in the practice. Federal laws mandating hydraulic companies to disclose fracturing fluid composition and concentration not only to federal and state regulatory agencies but also to health care professionals would encourage this practice. The full disclosure of fracturing chemicals will allow future research to fill knowledge gaps for a better understanding of the impacts of hydraulic fracturing on human health and the environment.

Modeling contaminant plumes in fractured limestone aquifers

DEFF Research Database (Denmark)

Mosthaf, Klaus; Brauns, Bentje; Fjordbøge, Annika Sidelmann

Determining the fate and transport of contaminant plumes from contaminated sites in limestone aquifers is important because they are a major drinking water resource. This is challenging because they are often heavily fractured and contain chert layers and nodules, resulting in a complex transport...... model. The paper concludes with recommendations on how to identify and employ suitable models to advance the conceptual understanding and as decision support tools for risk assessment and the planning of remedial actions....... behavior. Improved conceptual models are needed for this type of site. Here conceptual models are developed by combining numerical models with field data. Several types of fracture flow and transport models are available for the modeling of contaminant transport in fractured media. These include...... the established approaches of the equivalent porous medium, discrete fracture and dual continuum models. However, these modeling concepts are not well tested for contaminant plume migration in limestone geologies. Our goal was to develop and evaluate approaches for modeling the transport of dissolved contaminant...

Effect of Random Natural Fractures on Hydraulic Fracture Propagation Geometry in Fractured Carbonate Rocks

Science.gov (United States)

Liu, Zhiyuan; Wang, Shijie; Zhao, Haiyang; Wang, Lei; Li, Wei; Geng, Yudi; Tao, Shan; Zhang, Guangqing; Chen, Mian

2018-02-01

Natural fractures have a significant influence on the propagation geometry of hydraulic fractures in fractured reservoirs. True triaxial volumetric fracturing experiments, in which random natural fractures are created by placing cement blocks of different dimensions in a cuboid mold and filling the mold with additional cement to create the final test specimen, were used to study the factors that influence the hydraulic fracture propagation geometry. These factors include the presence of natural fractures around the wellbore, the dimension and volumetric density of random natural fractures and the horizontal differential stress. The results show that volumetric fractures preferentially formed when natural fractures occurred around the wellbore, the natural fractures are medium to long and have a volumetric density of 6-9%, and the stress difference is less than 11 MPa. The volumetric fracture geometries are mainly major multi-branch fractures with fracture networks or major multi-branch fractures (2-4 fractures). The angles between the major fractures and the maximum horizontal in situ stress are 30°-45°, and fracture networks are located at the intersections of major multi-branch fractures. Short natural fractures rarely led to the formation of fracture networks. Thus, the interaction between hydraulic fractures and short natural fractures has little engineering significance. The conclusions are important for field applications and for gaining a deeper understanding of the formation process of volumetric fractures.

Fracture flow due to hydrothermally induced quartz growth

Science.gov (United States)

Kling, Tobias; Schwarz, Jens-Oliver; Wendler, Frank; Enzmann, Frieder; Blum, Philipp

2017-09-01

Mineral precipitations are a common feature and limitation of initially open, permeable rock fractures by forming sealing structures or secondary roughness in open voids. Hence, the objective of this numerical study is the evaluation of hydraulic properties of fractures sealed by hydrothermally induced needle and compact quartz growth. Phase-field models of progressive syntaxial and idiomorphic quartz growth are implemented into a fluid flow simulation solving the Navier-Stokes equation. Flow simulations for both quartz types indicate an obvious correlation between changes in permeability, fracture properties (e.g. aperture, relative roughness and porosity) and crystal growth behavior, which also forms distinct flow paths. Thus, at lower sealing stages initial fracture permeability significantly drops down for the 'needle fracture' forming highly tortuous flow paths, while the 'compact fracture' records a considerably smaller loss. Fluid flow in both sealing fractures most widely is governed by a ;parallel plate;-like cubic law behavior. However, the 'needle fracture' also reveals flow characteristics of a porous media. A semi-theoretical equation is introduced that links geometrical (am) with hydraulically effective apertures (ah) and the relative fracture roughness. For this purpose, a geometry factor α is introduced being α = 2.5 for needle quartz and α = 1.0 for compact quartz growth. In contrast to most common ah-am-relationships this novel formulation not only reveals more precise predictions for the needle (RMSE = 1.5) and the compact fractures (RMSE = 3.2), but also exhibit a larger range of validity concerning the roughness of the 'needle' (σ/am = 0-2.4) and the 'compact fractures' (σ/am = 0-1.8).

Femoral neck fracture following groin irradiation

Energy Technology Data Exchange (ETDEWEB)

Grigsby, Perry W; Roberts, Heidi L; Perez, Carlos A

1995-04-30

Purpose: The incidence and risk factors are evaluated for femoral neck fracture following groin irradiation for gynecologic malignancies. Methods and Materials: The radiation therapy records of 1313 patients with advanced and recurrent cancer of the vagina, vulva, cervix, and endometrium, treated at the Mallinckrodt Institute of Radiology from 1954 to 1992, were reviewed. Median follow-up was 12.7 years. From this group, 207 patients were identified who received irradiation to the pelvis and groins with anterposterior-posterior anterior (AP-PA), 18 MV photons. Data were reviewed regarding irradiation dose to the femoral neck and other presumed risk factors including age, primary site, stage, groin node status, menopausal status, estrogen use, cigarette use, alcohol consumption, and osteoporosis. Results: The per-patient incidence of femoral neck fracture was 4.8% (10 out of 207). Four patients developed bilateral fractures. However, the cumulative actuarial incidence of fracture was 11% at 5 years and 15% at 10 years. Cox multivariate analysis of age, weight, and irradiation dose showed that only irradiation dose may be important to developing fracture. Step-wise logistic regression of presumed prognostic factors revealed that only cigarette use and x-ray evidence of osteoporosis prior to irradiation treatment were predictive of fracture. Conclusion: Femoral head fracture is a common complication of groin irradiation for gynecologic malignancies. Fracture in our database appears to be related to irradiation dose, cigarette use, and x-ray evidence of osteoporosis. Special attention should be given in treatment planning (i.e., shielding of femoral head/neck and use of appropriate electron beam energies for a portion of treatment) to reduce the incidence of this complication.

Femoral neck fracture following groin irradiation

International Nuclear Information System (INIS)

Grigsby, Perry W.; Roberts, Heidi L.; Perez, Carlos A.

1995-01-01

Purpose: The incidence and risk factors are evaluated for femoral neck fracture following groin irradiation for gynecologic malignancies. Methods and Materials: The radiation therapy records of 1313 patients with advanced and recurrent cancer of the vagina, vulva, cervix, and endometrium, treated at the Mallinckrodt Institute of Radiology from 1954 to 1992, were reviewed. Median follow-up was 12.7 years. From this group, 207 patients were identified who received irradiation to the pelvis and groins with anterposterior-posterior anterior (AP-PA), 18 MV photons. Data were reviewed regarding irradiation dose to the femoral neck and other presumed risk factors including age, primary site, stage, groin node status, menopausal status, estrogen use, cigarette use, alcohol consumption, and osteoporosis. Results: The per-patient incidence of femoral neck fracture was 4.8% (10 out of 207). Four patients developed bilateral fractures. However, the cumulative actuarial incidence of fracture was 11% at 5 years and 15% at 10 years. Cox multivariate analysis of age, weight, and irradiation dose showed that only irradiation dose may be important to developing fracture. Step-wise logistic regression of presumed prognostic factors revealed that only cigarette use and x-ray evidence of osteoporosis prior to irradiation treatment were predictive of fracture. Conclusion: Femoral head fracture is a common complication of groin irradiation for gynecologic malignancies. Fracture in our database appears to be related to irradiation dose, cigarette use, and x-ray evidence of osteoporosis. Special attention should be given in treatment planning (i.e., shielding of femoral head/neck and use of appropriate electron beam energies for a portion of treatment) to reduce the incidence of this complication

Advanced hydraulic fracturing methods to create in situ reactive barriers

International Nuclear Information System (INIS)

Murdoch, L.; Siegrist, B.; Vesper, S.

1997-01-01

Many contaminated areas consist of a source area and a plume. In the source area, the contaminant moves vertically downward from a release point through the vadose zone to an underlying saturated region. Where contaminants are organic liquids, NAPL may accumulate on the water table, or it may continue to migrate downward through the saturated region. Early developments of permeable barrier technology have focused on intercepting horizontally moving plumes with vertical structures, such as trenches, filled with reactive material capable of immobilizing or degrading dissolved contaminants. This focus resulted in part from a need to economically treat the potentially large volumes of contaminated water in a plume, and in part from the availability of construction technology to create the vertical structures that could house reactive compounds. Contaminant source areas, however, have thus far remained largely excluded from the application of permeable barrier technology. One reason for this is the lack of conventional construction methods for creating suitable horizontal structures that would place reactive materials in the path of downward-moving contaminants. Methods of hydraulic fracturing have been widely used to create flat-lying to gently dipping layers of granular material in unconsolidated sediments. Most applications thus far have involved filling fractures with coarse-grained sand to create permeable layers that will increase the discharge of wells recovering contaminated water or vapor. However, it is possible to fill fractures with other compounds that alter the chemical composition of the subsurface. One early application involved development and field testing micro-encapsulated sodium percarbonate, a solid compound that releases oxygen and can create aerobic conditions suitable for biodegradation in the subsurface for several months

MR findings in cases of suspected impacted fracture of the femoral neck

International Nuclear Information System (INIS)

Stiris, M.G.; Lilleaas, F.G.

1997-01-01

Purpose: To evaluate MR imaging of the hip in patients with a clinically suspected impacted fracture of the femoral neck in cases where conventional plain films show negative or equivocal findings. Material and Methods: Twenty-seven such patients were prospectively examined by MR imaging with a 1.0 T unit, within 24 hours of admittance to hospital. A coronal T1-weighted turbo spin-echo sequence (n=27), and a coronal STIR sequence (n=25) or a coronal T2-weighted turbo spin-echo fast saturation sequence (n=2) were used. The evaluations were made by 2 radiologists with experience in musculoskeletal radiology. Results: There were 6 patients with a petrochanteric fracture, 2 without and 4 with slight displacement. Five patients had an impacted fracture of the femoral neck, and 3 had a fracture of the superior pubic bone. Of 2 patients with advanced arthrosis, i had an impacted femoral neck fracture and the other a nondisplaced intertrochanteric fracture. There was 1 patient who had sustained a nondisplaced acetabular fracture with increased joint fluid and muscle contusions. Three patients had muscle contusions only. Two patients had bone marrow contusions only, while 2 others with advanced coxarthrosis had increased joint fluid only. Three patients showed normal findings. Our findings led to emergency surgery in 13 cases, and conservative measures directed to the specific MR findings in 14 patients. Conclusion: MR imaging should be the first modality of choice in examining patients with a clinically suspected impacted fracture of the femoral neck where conventional films show negative or equivocal findings. (orig.)

MR findings in cases of suspected impacted fracture of the femoral neck

Energy Technology Data Exchange (ETDEWEB)

Stiris, M.G.; Lilleaas, F.G. [Aker Hospital, Oslo (Norway). Dept. of Diagnostic Radiology

1997-09-01

Purpose: To evaluate MR imaging of the hip in patients with a clinically suspected impacted fracture of the femoral neck in cases where conventional plain films show negative or equivocal findings. Material and Methods: Twenty-seven such patients were prospectively examined by MR imaging with a 1.0 T unit, within 24 hours of admittance to hospital. A coronal T1-weighted turbo spin-echo sequence (n=27), and a coronal STIR sequence (n=25) or a coronal T2-weighted turbo spin-echo fast saturation sequence (n=2) were used. The evaluations were made by 2 radiologists with experience in musculoskeletal radiology. Results: There were 6 patients with a petrochanteric fracture, 2 without and 4 with slight displacement. Five patients had an impacted fracture of the femoral neck, and 3 had a fracture of the superior pubic bone. Of 2 patients with advanced arthrosis, i had an impacted femoral neck fracture and the other a nondisplaced intertrochanteric fracture. There was 1 patient who had sustained a nondisplaced acetabular fracture with increased joint fluid and muscle contusions. Three patients had muscle contusions only. Two patients had bone marrow contusions only, while 2 others with advanced coxarthrosis had increased joint fluid only. Three patients showed normal findings. Our findings led to emergency surgery in 13 cases, and conservative measures directed to the specific MR findings in 14 patients. Conclusion: MR imaging should be the first modality of choice in examining patients with a clinically suspected impacted fracture of the femoral neck where conventional films show negative or equivocal findings. (orig.).

Pediatric mandibular fractures.

Science.gov (United States)

Schweinfurth, J M; Koltai, P J

1998-01-01

Over the last 20 years, a revolution in the management of facial fractures has taken place. Refinements in biocompatible materials of great delicacy and strength along with advances in our understanding of biomechanics of the face, have rendered complex injuries consistently amenable to accurate 3-dimensional reconstruction. Furthermore, with the availability of education in the techniques of internal rigid fixation, these advanced techniques have become routine practice in adults. However, the suitability of rigid internal fixation for children remains controversial. There are many concerns about the effect of implanted hardware in the mandible of a growing child. In addition, some evidence suggests that the elevation of functional matrix off of bone may result in alterations in development. The goal is to restore the underlying bony architecture to its pre-injury position in a stable fashion, with a minimal of aesthetic and functional impairment. However, in children the treatment of bony injuries is most easily accomplished by techniques that may adversely effect craniofacial development. While it is not entirely possible to resolve this dilemma, there exists an extensive body of experimental and clinical information on the appropriate management of pediatric mandibular fractures which can be used to formulate a rational treatment plan for most cases. This paper presents an overview of the contemporary understanding and application of these treatment principles.

Clinical Analysis for the Correlation of Intra-abdominal Organ Injury in the Patients with Rib Fracture

OpenAIRE

Park, Seongsik

2012-01-01

Background Although it is rare for the fracture itself to become a life threatening injury in patients suffering from rib fracture, the lives of these patients are occasionally threatened by other associated injuries. Especially, early discovery of patients with rib fracture and intra-abdominal organ injury is extremely important to the prognosis. This study analyzed the link between rib fracture and intra-abdominal injury to achieve improved treatment. Materials and Methods Among trauma pati...

Fracture resistance curves and toughening mechanisms in polymer based dental composites

DEFF Research Database (Denmark)

De Souza, J.A.; Goutianos, Stergios; Skovgaard, M.

2011-01-01

The fracture resistance (R-curve behaviour) of two commercial dental composites (Filtek Z350® and Concept Advanced®) were studied using Double Cantilever Beam sandwich specimens loaded with pure bending moments to obtain stable crack growth. The experiments were conducted in an environmental...... significantly higher fracture resistance than the composite with the coarser microstructure. The fracture properties were related to the flexural strength of the dental composites. The method, thus, can provide useful insight into how the microstructure enhances toughness, which is necessary for the future...

Mechanisms Underlying Stress Fracture and the Influence of Sex and Race/Ethnicity

Science.gov (United States)

2017-10-01

AWARD NUMBER: W81XWH-16-1-0652 TITLE: Mechanisms Underlying Stress Fracture and the Influence of Sex and Race/Ethnicity PRINCIPAL INVESTIGATOR...5a. CONTRACT NUMBER W81XWH-16-1-0652 Mechanisms Underlying Stress Fracture and the Influence of Sex and Race/Ethnicity 5b. GRANT NUMBER W81XWH...to stress fracture risk. In particular, in Study 1, we will perform advanced skeletal imaging along with gait-assessments in subjects with history of

Incidence of fractures in patients with multiple sclerosis: the Danish National Health Registers

DEFF Research Database (Denmark)

Bazelier, Marloes T; de Vries, Frank; Bentzen, Joan

2012-01-01

Background: Patients with multiple sclerosis (MS) are potentially at high risk of fracture due to falls and osteoporosis. Objective: To estimate incidence rates of fractures in MS patients, stratified by fracture type, sex and age, and to compare these rates with controls. Methods: The case...... population consisted of all patients with an accepted diagnosis of MS in the Danish MS Registry (1949-2007). Data were linked to the National Hospital Discharge Register (1977-2007). Patients with MS (n = 11,157) were 1: 6 matched by year of birth, gender, calendar time and region to persons without MS...... (controls). Incidence rates of fracture were estimated as the number of fractures per 1000 person-years. Incidence rate ratios (IRRs) were calculated by dividing fracture rates in MS patients by fracture rates in controls. Results: Among patients with MS, the incidence rate of any fracture yielded 22.8 per...

Role of MRI in hip fractures, including stress fractures, occult fractures, avulsion fractures

International Nuclear Information System (INIS)

Nachtrab, O.; Cassar-Pullicino, V.N.; Lalam, R.; Tins, B.; Tyrrell, P.N.M.; Singh, J.

2012-01-01

MR imaging plays a vital role in the diagnosis and management of hip fractures in all age groups, in a large spectrum of patient groups spanning the elderly and sporting population. It allows a confident exclusion of fracture, differentiation of bony from soft tissue injury and an early confident detection of fractures. There is a spectrum of MR findings which in part is dictated by the type and cause of the fracture which the radiologist needs to be familiar with. Judicious but prompt utilisation of MR in patients with suspected hip fractures has a positive therapeutic impact with healthcare cost benefits as well as social care benefits.

Paratrooper's ankle fracture: posterior malleolar fracture.

Science.gov (United States)

Young, Ki Won; Kim, Jin-su; Cho, Jae Ho; Kim, Hyung Seuk; Cho, Hun Ki; Lee, Kyung Tai

2015-03-01

We assessed the frequency and types of ankle fractures that frequently occur during parachute landings of special operation unit personnel and analyzed the causes. Fifty-six members of the special force brigade of the military who had sustained ankle fractures during parachute landings between January 2005 and April 2010 were retrospectively analyzed. The injury sites and fracture sites were identified and the fracture types were categorized by the Lauge-Hansen and Weber classifications. Follow-up surveys were performed with respect to the American Orthopedic Foot and Ankle Society ankle-hindfoot score, patient satisfaction, and return to preinjury activity. The patients were all males with a mean age of 23.6 years. There were 28 right and 28 left ankle fractures. Twenty-two patients had simple fractures and 34 patients had comminuted fractures. The average number of injury and fractures sites per person was 2.07 (116 injuries including a syndesmosis injury and a deltoid injury) and 1.75 (98 fracture sites), respectively. Twenty-three cases (41.07%) were accompanied by posterior malleolar fractures. Fifty-five patients underwent surgery; of these, 30 had plate internal fixations. Weber type A, B, and C fractures were found in 4, 38, and 14 cases, respectively. Based on the Lauge-Hansen classification, supination-external rotation injuries were found in 20 cases, supination-adduction injuries in 22 cases, pronation-external rotation injuries in 11 cases, tibiofibular fractures in 2 cases, and simple medial malleolar fractures in 2 cases. The mean follow-up period was 23.8 months, and the average follow-up American Orthopedic Foot and Ankle Society ankle-hindfoot score was 85.42. Forty-five patients (80.36%) reported excellent or good satisfaction with the outcome. Posterior malleolar fractures occurred in 41.07% of ankle fractures sustained in parachute landings. Because most of the ankle fractures in parachute injuries were compound fractures, most cases had to

Multiple vertebral fractures in an elderly male with macroprolactinoma

Directory of Open Access Journals (Sweden)

Saša Magaš

2016-09-01

Full Text Available Hyperprolactinemia is associated with increased bone loss both in men and women. We report a case of an elderly patient with multiple osteoporotic vertebral fractures due to long-lasting hypogonadism caused by prolactinoma. The patient was treated with transphenoidal surgery, small doses of dopamine agonists, teriparatide, calcium and vitamin D supplements. Treatment led to increase in bone mineral density and decrease in lumbar pain intensity. This case highlights that clinicians should bear in mind the fact that osteoporotic vertebral fractures in men may be linked with hypogonadism and hyperprolactinemia. These conditions can be effectively treated. Therefore, detailed medical history and appropriate endocrinological evaluation should be performed in all male patients with osteoporotic fractures.

Complex association between body weight and fracture risk in postmenopausal women.

Science.gov (United States)

Mpalaris, V; Anagnostis, P; Goulis, D G; Iakovou, I

2015-03-01

Osteoporosis is a common disease, characterized by low bone mass with micro-architectural disruption and skeletal fragility, resulting in an increased risk of fracture. A substantial number of studies has examined the possible relationship between body weight, bone mineral density and fracture risk in post-menopausal women, with the majority of them concluding that low body weight correlates with increased risk of fracture, especially hip fracture. Controversies about the potential protective effect of obesity on osteoporosis and consequent fracture risk still exist. Several recent studies question the concept that obesity exerts a protective effect against fractures, suggesting that it stands as a risk factor for fractures at specific skeletal sites, such as upper arm. The association between body weight and fracture risk is complex, differs across skeletal sites and body mass index, and is modified by the interaction between body weight and bone mineral density. Some potential explanations that link obesity with increased fracture risk may be the pattern of falls and impaired mobility in obese individuals, comorbidities, such as asthma, diabetes and early menopause, as well as, increased parathyroid hormone and reduced 25-hydroxy-vitamin D concentrations. © 2015 World Obesity.

Modelling of Local Necking and Fracture in Aluminium Alloys

International Nuclear Information System (INIS)

Achani, D.; Eriksson, M.; Hopperstad, O. S.; Lademo, O.-G.

2007-01-01

Non-linear Finite Element simulations are extensively used in forming and crashworthiness studies of automotive components and structures in which fracture need to be controlled. For thin-walled ductile materials, the fracture-related phenomena that must be properly represented are thinning instability, ductile fracture and through-thickness shear instability. Proper representation of the fracture process relies on the accuracy of constitutive and fracture models and their parameters that need to be calibrated through well defined experiments. The present study focuses on local necking and fracture which is of high industrial importance, and uses a phenomenological criterion for modelling fracture in aluminium alloys. As an accurate description of plastic anisotropy is important, advanced phenomenological constitutive equations based on the yield criterion YLD2000/YLD2003 are used. Uniaxial tensile tests and disc compression tests are performed for identification of the constitutive model parameters. Ductile fracture is described by the Cockcroft-Latham fracture criterion and an in-plane shear tests is performed to identify the fracture parameter. The reason is that in a well designed in-plane shear test no thinning instability should occur and it thus gives more direct information about the phenomenon of ductile fracture. Numerical simulations have been performed using a user-defined material model implemented in the general-purpose non-linear FE code LS-DYNA. The applicability of the model is demonstrated by correlating the predicted and experimental response in the in-plane shear tests and additional plane strain tension tests

Linking advanced biofuels policies with stakeholder interests: A method building on Quality Function Deployment

International Nuclear Information System (INIS)

Schillo, R. Sandra; Isabelle, Diane A.; Shakiba, Abtin

2017-01-01

The field of renewable energy policy is inherently complex due to the long-term impacts of its policies, the broad range of potential stakeholders, the intricacy of scientific, engineering and technological developments, and the interplay of complex policy mixes that may result in unintended consequences. Quality Function Deployment (QFD) provides a systematic consideration of all relevant stakeholders, a rigorous analysis of the needs of stakeholders, and a prioritization of design features based on stakeholders needs. We build on QFD combined with Analytical Hierarchy Process (AHP) to develop a novel method applied to the area of advanced biofuel policies. This Multi-Stakeholder Policy QFD (MSP QFD) provides a systematic approach to capture the voice of the stakeholders and align it with the broad range of potential advanced biofuels policies. To account for the policy environment, the MSP QFD utilizes a novel approach to stakeholder importance weights. This MSP QFD adds to the literature as it permits the analysis of the broad range of relevant national policies with regards to the development of advanced biofuels, as compared to more narrowly focused typical QFD applications. It also allows policy developers to gain additional insights into the perceived impacts of policies, as well as international comparisons. - Highlights: • Advanced biofuels are mostly still in research and early commercialization stages. • Government policies are expected to support biofuels stakeholders in market entry. • A Multi-Stakeholder Policy QFD (MSP QFD) links biofuels policies with stakeholders. • MSP QFD employs novel stakeholder weights method. • The case of advanced biofuels in Canada shows comparative importance of policies.

ADVANCED CHARACTERIZATION OF FRACTURED RESERVOIRS IN CARBONATE ROCKS: THE MICHIGAN BASIN

Energy Technology Data Exchange (ETDEWEB)

James R. Wood; William B. Harrison

2002-12-01

The purpose of the study was to collect and analyze existing data on the Michigan Basin for fracture patterns on scales ranging form thin section to basin. The data acquisition phase has been successfully concluded with the compilation of several large digital databases containing nearly all the existing information on formation tops, lithology and hydrocarbon production over the entire Michigan Basin. These databases represent the cumulative result of over 80 years of drilling and exploration. Plotting and examination of these data show that contrary to most depictions, the Michigan Basin is in fact extensively faulted and fractured, particularly in the central portion of the basin. This is in contrast to most of the existing work on the Michigan Basin, which tends to show relatively simple structure with few or minor faults. It also appears that these fractures and faults control the Paleozoic sediment deposition, the subsequent hydrocarbon traps and very likely the regional dolomitization patterns. Recent work has revealed that a detailed fracture pattern exists in the interior of the Central Michigan Basin, which is related to the mid-continent gravity high. The inference is that early Precambrian, ({approx}1 Ga) rifting events presumed by many to account for the gravity anomaly subsequently controlled Paleozoic sedimentation and later hydrocarbon accumulation. There is a systematic relationship between the faults and a number of gas and oil reservoirs: major hydrocarbon accumulations consistently occur in small anticlines on the upthrown side of the faults. The main tools used in this study to map the fault/fracture patterns are detailed, close-interval (CI = 10 feet) contouring of the formation top picks accompanied by a new way of visualizing the data using a special color spectrum to bring out the third dimension. In addition, recent improvements in visualization and contouring software were instrumental in the study. Dolomitization is common in the

Subsurface fracture mapping from geothermal wellbores. Final report

Energy Technology Data Exchange (ETDEWEB)

Hartenbaum, B.A.; Rawson, G.

1983-08-01

To advance the state-of-the-art in Hot Dry Rock technology, and evaluation is made of (1) the use of both electromagnetic and acoustic radar to map far-field fractures, (2) the use of more than twenty different conventional well logging tools to map borehole-fracture intercepts, (3) the use of magnetic dipole ranging to determine the relative positions of the injection well and the production well within the fractured zone, (4) the use of passive microseismic methods to determine the orientation and extent of hydraulic fractures, and (5) the application of signal processing techniques to fracture mapping including tomography, holography, synthetic aperture, image reconstruction, and the relative importance of phase and amplitude information. It is found that according to calculations, VHF backscatter radar has the potential for mapping fractures within a distance of 50 +- 20 meters from the wellbore. A new technique for improving fracture identification is presented. The range of acoustic radar is five to seven times greater than that of VHF radar when compared on the basis of equal resolution, i.e., equal wavelengths. Analyses of extant data indicate that when used synergistically the (1) caliper, (2) resistivity dipmeter, (3) televiewer, (4) television, (5) impression packer, and (6) acoustic transmission are useful for mapping borehole-fracture intercepts. A new model of hydraulic fracturing is presented which indicates that a hydraulic fracture is dynamically unstable; consequently, improvements in locating the crack tip may be possible. The importance of phase in signal processing is stressed and those techniques which employ phase data are emphasized for field use.

High-Risk Stress Fractures: Diagnosis and Management.

Science.gov (United States)

McInnis, Kelly C; Ramey, Lindsay N

2016-03-01

Stress fractures are common overuse injuries in athletes. They occur during periods of increased training without adequate rest, disrupting normal bone reparative mechanisms. There are a host of intrinsic and extrinsic factors, including biochemical and biomechanical, that put athletes at risk. In most stress fractures, the diagnosis is primarily clinical, with imaging indicated at times, and management focused on symptom-free relative rest with advancement of activity as tolerated. Overall, stress fractures in athletes have an excellent prognosis for return to sport, with little risk of complication. There is a subset of injuries that have a greater risk of fracture progression, delayed healing, and nonunion and are generally more challenging to treat with nonoperative care. Specific locations of high-risk stress fracture include the femoral neck (tension side), patella, anterior tibia, medial malleolus, talus, tarsal navicular, proximal fifth metatarsal, and great toe sesamoids. These sites share a characteristic region of high tensile load and low blood flow. High-risk stress fractures require a more aggressive approach to evaluation, with imaging often necessary, to confirm early and accurate diagnosis and initiate immediate treatment. Treatment consists of nonweight-bearing immobilization, often with a prolonged period away from sport, and a more methodic and careful reintroduction to athletic activity. These stress fractures may require surgical intervention. A high index of suspicion is essential to avoid delayed diagnosis and optimize outcomes in this subset of stress fractures. Copyright © 2016 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

Spills of Hydraulic Fracturing Chemicals on Agricultural Topsoil: Biodegradation, Sorption, and Co-contaminant Interactions.

Science.gov (United States)

McLaughlin, Molly C; Borch, Thomas; Blotevogel, Jens

2016-06-07

Hydraulic fracturing frequently occurs on agricultural land. Yet the extent of sorption, transformation, and interactions among the numerous organic frac fluid and oil and gas wastewater constituents upon environmental release is hardly known. Thus, this study aims to advance our current understanding of processes that control the environmental fate and toxicity of commonly used hydraulic fracturing chemicals. Poly(ethylene glycol) surfactants were completely biodegraded in agricultural topsoil within 42-71 days, but their transformation was impeded in the presence of the biocide glutaraldehyde and was completely inhibited by salt at concentrations typical for oil and gas wastewater. At the same time, aqueous glutaraldehyde concentrations decreased due to sorption to soil and were completely biodegraded within 33-57 days. While no aqueous removal of polyacrylamide friction reducer was observed over a period of 6 months, it cross-linked with glutaraldehyde, further lowering the biocide's aqueous concentration. These findings highlight the necessity to consider co-contaminant effects when we evaluate the risk of frac fluid additives and oil and gas wastewater constituents in agricultural soils in order to fully understand their human health impacts, likelihood for crop uptake, and potential for groundwater contamination.

Fracture Mechanics

International Nuclear Information System (INIS)

Jang, Dong Il; Jeong, Gyeong Seop; Han, Min Gu

1992-08-01

This book introduces basic theory and analytical solution of fracture mechanics, linear fracture mechanics, non-linear fracture mechanics, dynamic fracture mechanics, environmental fracture and fatigue fracture, application on design fracture mechanics, application on analysis of structural safety, engineering approach method on fracture mechanics, stochastic fracture mechanics, numerical analysis code and fracture toughness test and fracture toughness data. It gives descriptions of fracture mechanics to theory and analysis from application of engineering.

Mechanical Behaviour of Materials Volume II Fracture Mechanics and Damage

CERN Document Server

François, Dominique; Zaoui, André

2013-01-01

Designing new structural materials, extending lifetimes and guarding against fracture in service are among the preoccupations of engineers, and to deal with these they need to have command of the mechanics of material behaviour. This ought to reflect in the training of students. In this respect, the first volume of this work deals with elastic, elastoplastic, elastoviscoplastic and viscoelastic behaviours; this second volume continues with fracture mechanics and damage, and with contact mechanics, friction and wear. As in Volume I, the treatment links the active mechanisms on the microscopic scale and the laws of macroscopic behaviour. Chapter I is an introduction to the various damage phenomena. Chapter II gives the essential of fracture mechanics. Chapter III is devoted to brittle fracture, chapter IV to ductile fracture and chapter V to the brittle-ductile transition. Chapter VI is a survey of fatigue damage. Chapter VII is devoted to hydogen embrittlement and to environment assisted cracking, chapter VIII...

Specimen-specific modeling of hip fracture pattern and repair.

Science.gov (United States)

Ali, Azhar A; Cristofolini, Luca; Schileo, Enrico; Hu, Haixiang; Taddei, Fulvia; Kim, Raymond H; Rullkoetter, Paul J; Laz, Peter J

2014-01-22

Hip fracture remains a major health problem for the elderly. Clinical studies have assessed fracture risk based on bone quality in the aging population and cadaveric testing has quantified bone strength and fracture loads. Prior modeling has primarily focused on quantifying the strain distribution in bone as an indicator of fracture risk. Recent advances in the extended finite element method (XFEM) enable prediction of the initiation and propagation of cracks without requiring a priori knowledge of the crack path. Accordingly, the objectives of this study were to predict femoral fracture in specimen-specific models using the XFEM approach, to perform one-to-one comparisons of predicted and in vitro fracture patterns, and to develop a framework to assess the mechanics and load transfer in the fractured femur when it is repaired with an osteosynthesis implant. Five specimen-specific femur models were developed from in vitro experiments under a simulated stance loading condition. Predicted fracture patterns closely matched the in vitro patterns; however, predictions of fracture load differed by approximately 50% due to sensitivity to local material properties. Specimen-specific intertrochanteric fractures were induced by subjecting the femur models to a sideways fall and repaired with a contemporary implant. Under a post-surgical stance loading, model-predicted load sharing between the implant and bone across the fracture surface varied from 59%:41% to 89%:11%, underscoring the importance of considering anatomic and fracture variability in the evaluation of implants. XFEM modeling shows potential as a macro-level analysis enabling fracture investigations of clinical cohorts, including at-risk groups, and the design of robust implants. © 2013 Published by Elsevier Ltd.

Slug flow model for infiltration into fractured porous media

International Nuclear Information System (INIS)

Martinez, M.J.

1999-01-01

A model for transient infiltration into a periodically fractured porous layer is presented. The fracture is treated as a permeable-walled slot and the moisture distribution is in the form of a slug being an advancing meniscus. The wicking of moisture from the fracture to the unsaturated porous matrix is a nonlinear diffusion process and is approximately by self-similar solutions. The resulting model is a nonlinear Volterra integral equation with a weakly singular kernel. Numerical analysis provides solutions over a wide range of the parameter space and reveals the asymptotic forms of the penetration of this slug in terms of dimensionless variables arising in the model. The numerical solutions corroborate asymptotic results given earlier by Nitao and Buscheck (1991), and by Martinez (1988). Some implications for the transport of liquid in fractured rock are discussed

3D printing application and numerical simulations in a fracture system

Science.gov (United States)

Yoon, H.; Martinez, M. J.

2017-12-01

The hydrogeological and mechanical properties in fractured and porous media are fundamental to predicting coupled multiphysics processes in the subsurface. Recent advances in experimental methods and multi-scale imaging capabilities have revolutionized our ability to quantitatively characterize geomaterials and digital counterparts are now routinely used for numerical simulations to characterize petrophysical and mechanical properties across scales. 3D printing is a very effective and creative technique that reproduce the digital images in a controlled way. For geoscience applications, 3D printing can be co-opted to print reproducible porous and fractured structures derived from CT-imaging of actual rocks and theoretical algorithms for experimental testing. In this work we used a stereolithography (SLA) method to create a single fracture network. The fracture in shale was first scanned using a microCT system and then the digital fracture network was printed into two parts and assembled. Aperture ranges from 0.3 to 1 mm. In particular, we discuss the design of single fracture network and the progress of printing practices to reproduce the fracture network system. Printed samples at different scales are used to measure the permeability and surface roughness. Various numerical simulations including (non-)reactive transport and multiphase flow cases are performed to study fluid flow characterization. We will also discuss the innovative advancement of 3D printing techniques applicable for coupled processes in the subsurface. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA0003525.

Inter- and intra-agglomerate fracture in nanocrystalline nickel.

Science.gov (United States)

Shan, Zhiwei; Knapp, J A; Follstaedt, D M; Stach, E A; Wiezorek, J M K; Mao, S X

2008-03-14

In situ tensile straining transmission electron microscopy tests have been carried out on nanocrystalline Ni. Grain agglomerates (GAs) were found to form very frequently and rapidly ahead of an advancing crack with sizes much larger than the initial average grain size. High-resolution electron microscopy indicated that the GAs most probably consist of nanograins separated by low-angle grain boundaries. Furthermore, both inter- and intra-GA fractures were observed. The observations suggest that these newly formed GAs may play an important role in the formation of the dimpled fracture surfaces of nanocrystalline materials.

Tibial stress fractures in racing Standardbreds: 13 cases (1989-1993)

International Nuclear Information System (INIS)

Ruggles, A.J.; Moore, R.M.; Bertone, A.L.; Schneider, R.K.; Bailey, M.Q.

1996-01-01

To determine clinical signs, radiographic and scintigraphic findings, and performance outcome of racing Standardbreds with tibial stress fractures. Retrospective case series. 13 racing Standardbreds with tibial stress fractures. Information concerning clinical signs, diagnostic evaluation, and recommendations was obtained by review of the medical records. Performance information before and after diagnosis of the fracture was collected from racing records, and follow-up information was obtained from the owners or trainers by use of a telephone questionnaire. Horses with tibial stress fractures were moderately lame, and diagnosis was made by nuclear scintigraphy and radiography. Fractures were more likely to occur in 2-year-old horses than in older horses. The fracture location was unique for Standardbreds; 11 of 13 developed stress fractures in the mid-diaphysis of the tibia, whereas fractures in Thoroughbreds are usually in the proximal caudal or caudolateral cortex. Fractures occurred in young horses that had raced or were in advanced race training. All horses were treated with rest alone, and 10 of 13 horses raced after injury. The horses that raced after injury were able to return to a level of performance that was equal to or better than the level raced before injury. 8 of 10 horses established a lifetime-best winning time after injury. Tibial stress fractures are a cause of lameness in young racing Standardbreds. Diagnosis is aided by nuclear scintigraphy. The prognosis for return to previous level of performance after a tibial stress fracture is good

Model of T-Type Fracture in Coal Fracturing and Analysis of Influence Factors of Fracture Morphology

Directory of Open Access Journals (Sweden)

Yuwei Li

2018-05-01

Full Text Available Special T-type fractures can be formed when coal is hydraulically fractured and there is currently no relevant theoretical model to calculate and describe them. This paper first establishes the height calculation model of vertical fractures in multi-layered formations and deduces the stress intensity factor (SIF at the upper and lower sides of the fracture in the process of vertical fracture extension. Combined with the fracture tip stress analysis method of fracture mechanics theory, the horizontal bedding is taken into account for tensile and shear failure, and the critical mechanical conditions for the formation of horizontal fracture in coal are obtained. Finally, the model of T-type fracture in coal fracturing is established, and it is verified by fracturing simulation experiments. The model calculation result shows that the increase of vertical fracture height facilitates the increase of horizontal fracture length. The fracture toughness of coal has a significant influence on the length of horizontal fracture and there is a threshold. When the fracture toughness is less than the threshold, the length of horizontal fracture remains unchanged, otherwise, the length of horizontal fracture increases rapidly with the increase of fracture toughness. When the shear strength of the interface between the coalbed and the interlayer increases, the length of the horizontal fracture of the T-type fracture rapidly decreases.

Early Onset of Laying and Bumblefoot Favor Keel Bone Fractures

Science.gov (United States)

Gebhardt-Henrich, Sabine G.; Fröhlich, Ernst K. F.

2015-01-01

Simple Summary Numerous studies have documented a high prevalence of keel bone fractures in laying hens. In this longitudinal study, 80 white and brown laying hens were regularly checked for keel bone deviations and fractures while egg production was individually monitored. About 62% of the hens had broken keel bones at depopulation. More new fractures occurred during the time when laying rates were highest. Hens with broken keel bones at depopulation had laid their first egg earlier than hens with intact keel bones. All birds with bumblefoot on both feet had a fracture at depopulation. Abstract Numerous studies have demonstrated influences of hybrid, feed, and housing on prevalence of keel bone fractures, but influences of behavior and production on an individual level are less known. In this longitudinal study, 80 white and brown laying hens were regularly checked for keel bone deviations and fractures while egg production was individually monitored using Radio Frequency Identification (RFID) from production until depopulation at 65 weeks of age. These focal birds were kept in eight pens with 20 hens per pen in total. About 62% of the hens had broken keel bones at depopulation. The occurrence of new fractures was temporally linked to egg laying: more new fractures occurred during the time when laying rates were highest. Hens with fractured keel bones at depopulation had laid their first egg earlier than hens with intact keel bones. However, the total number of eggs was neither correlated with the onset of egg laying nor with keel bone fractures. All birds with bumblefoot on both feet had a fracture at depopulation. Hens stayed in the nest for a longer time during egg laying during the ten days after the fracture than during the ten days before the fracture. In conclusion, a relationship between laying rates and keel bone fractures seems likely. PMID:26633520

Empirically Based Composite Fracture Prediction Model From the Global Longitudinal Study of Osteoporosis in Postmenopausal Women (GLOW)

Science.gov (United States)

Compston, Juliet E.; Chapurlat, Roland D.; Pfeilschifter, Johannes; Cooper, Cyrus; Hosmer, David W.; Adachi, Jonathan D.; Anderson, Frederick A.; Díez-Pérez, Adolfo; Greenspan, Susan L.; Netelenbos, J. Coen; Nieves, Jeri W.; Rossini, Maurizio; Watts, Nelson B.; Hooven, Frederick H.; LaCroix, Andrea Z.; March, Lyn; Roux, Christian; Saag, Kenneth G.; Siris, Ethel S.; Silverman, Stuart; Gehlbach, Stephen H.

2014-01-01

Context: Several fracture prediction models that combine fractures at different sites into a composite outcome are in current use. However, to the extent individual fracture sites have differing risk factor profiles, model discrimination is impaired. Objective: The objective of the study was to improve model discrimination by developing a 5-year composite fracture prediction model for fracture sites that display similar risk profiles. Design: This was a prospective, observational cohort study. Setting: The study was conducted at primary care practices in 10 countries. Patients: Women aged 55 years or older participated in the study. Intervention: Self-administered questionnaires collected data on patient characteristics, fracture risk factors, and previous fractures. Main Outcome Measure: The main outcome is time to first clinical fracture of hip, pelvis, upper leg, clavicle, or spine, each of which exhibits a strong association with advanced age. Results: Of four composite fracture models considered, model discrimination (c index) is highest for an age-related fracture model (c index of 0.75, 47 066 women), and lowest for Fracture Risk Assessment Tool (FRAX) major fracture and a 10-site model (c indices of 0.67 and 0.65). The unadjusted increase in fracture risk for an additional 10 years of age ranges from 80% to 180% for the individual bones in the age-associated model. Five other fracture sites not considered for the age-associated model (upper arm/shoulder, rib, wrist, lower leg, and ankle) have age associations for an additional 10 years of age from a 10% decrease to a 60% increase. Conclusions: After examining results for 10 different bone fracture sites, advanced age appeared the single best possibility for uniting several different sites, resulting in an empirically based composite fracture risk model. PMID:24423345

Adherence to a Mediterranean diet and risk of fractures in French older persons.

Science.gov (United States)

Feart, C; Lorrain, S; Ginder Coupez, V; Samieri, C; Letenneur, L; Paineau, D; Barberger-Gateau, P

2013-12-01

Prevention of fractures is a considerable public health challenge. In a population-based cohort of French elderly people, a diet closer to a Mediterranean type had a borderline significant deleterious effect on the risk of fractures, in part linked to a low consumption of dairy products and a high consumption of fruits. Higher adherence to the Mediterranean diet (MeDi) is linked to a lower risk of several chronic diseases, but its association with the risk of fractures is unclear. Our aim was to investigate the association between MeDi adherence and the risk of fractures in older persons. The sample consisted of 1,482 individuals aged 67 years or older, from Bordeaux, France, included in the Three-City Study in 2001-2002. Occurrences of hip, vertebral and wrist fractures were self-reported every 2 years over 8 years, and 155 incident fractures were recorded. Adherence to the MeDi was evaluated at baseline by a MeDi score, on a 10-point scale based on a food frequency questionnaire and a 24-h recall. Multivariate Cox regression tests were performed to estimate the risk of fractures according to MeDi adherence. Higher MeDi adherence was associated with a non-significant increased risk of fractures at any site (hazard ratio [HR] per 1-point increase of MeDi score = 1.10, P = 0.08) in fully adjusted model. Among MeDi components, higher fruits consumption (>2 servings/day) was significantly associated with an increased risk of hip fractures (HR = 1.95, P = 0.04), while low intake of dairy products was associated with a doubled risk of wrist fractures (HR = 2.03, P = 0.007). An inverse U-shaped association between alcohol intake and risk of total fracture was observed (HR high vs. moderate = 0.61, P for trend = 0.03). Greater MeDi adherence was not associated with a decreased risk of fractures in French older persons. The widely recognized beneficial effects of the MeDi do not seem to apply to bone health in these people.

The influence of the reciprocal hip joint link in the advanced reciprocating gait orthosis on standing performance in paraplegia

NARCIS (Netherlands)

Baardman, G.; IJzerman, Maarten Joost; Hermens, Hermanus J.; Veltink, Petrus H.; Boom, H.B.K.; Zilvold, G.; Zilvold, G.

1997-01-01

The effect of reciprocally linking the hip hinges of a hip-knee-ankle-foot orthosis on standing performance was studied in a comparative trial of the Advanced Reciprocating Gait Orthosis (ARGO) and an ARGO in which the Bowden cable was removed (A_GO). Six male subjects with spinal cord injury (SCI)

The Advanced Linked Extended Reconnaissance & Targeting Technology Demonstration project

Science.gov (United States)

Edwards, Mark

2008-04-01

The Advanced Linked Extended Reconnaissance & Targeting (ALERT) Technology Demonstration (TD) project is addressing many operational needs of the future Canadian Army's Surveillance and Reconnaissance forces. Using the surveillance system of the Coyote reconnaissance vehicle as an experimental platform, the ALERT TD project aims to significantly enhance situational awareness by fusing multi-sensor and tactical data, developing automated processes, and integrating beyond line-of-sight sensing. The project is exploiting important advances made in computer processing capability, displays technology, digital communications, and sensor technology since the design of the original surveillance system. As the major research area within the project, concepts are discussed for displaying and fusing multi-sensor and tactical data within an Enhanced Operator Control Station (EOCS). The sensor data can originate from the Coyote's own visible-band and IR cameras, laser rangefinder, and ground-surveillance radar, as well as from beyond line-of-sight systems such as mini-UAVs and unattended ground sensors. Video-rate image processing has been developed to assist the operator to detect poorly visible targets. As a second major area of research, automatic target cueing capabilities have been added to the system. These include scene change detection, automatic target detection and aided target recognition algorithms processing both IR and visible-band images to draw the operator's attention to possible targets. The merits of incorporating scene change detection algorithms are also discussed. In the area of multi-sensor data fusion, up to Joint Defence Labs level 2 has been demonstrated. The human factors engineering aspects of the user interface in this complex environment are presented, drawing upon multiple user group sessions with military surveillance system operators. The paper concludes with Lessons Learned from the project. The ALERT system has been used in a number of C4ISR

Correcting underestimation of optimal fracture length by modeling proppant conductivity variations in hydraulically fractured gas/condensate reservoirs

Energy Technology Data Exchange (ETDEWEB)

Akram, A.H.; Samad, A. [Society of Petroleum Engineers, Richardson, TX (United States)]|[Schlumberger, Houston, TX (United States)

2006-07-01

A study was conducted in which a newly developed numerical simulator was used to forecast the productivity of a hydraulically fractured well in a retrograde gas-condensate sandstone reservoir. The effect of condensate dropout was modeled in both the reservoir and the proppant pack. The type of proppant and the stress applied to it are among the factors that determine proppant conductivity in a single-phase flow. Other factors include the high velocity of gas and the presence of liquid in the proppant pack. It was concluded that apparent proppant permeability in a gas condensate reservoir varies along the length of the hydraulic fracture and depends on the distance from the wellbore. It will increase towards the tip of the fracture where liquid ratio and velocity are lower. Apparent proppant permeability also changes with time. Forecasting is most accurate when these conditions are considered in the simulation. There are 2 problems associated with the use of a constant proppant permeability in a gas condensate reservoir. The first relates to the fact that it is impossible to obtain a correct single number that will mimic the drawdown of the real fracture at a particular rate without going through the process of determining the proppant permeability profile in a numerical simulator. The second problem relates to the fact that constant proppant permeability yields an optimal fracture length that is too short. Analytical modeling does not account for these complexities. It was determined that the only way to accurately simulate the behaviour of a hydraulic fracture in a high rate well, is by advanced numerical modeling that considers varying apparent proppant permeability in terms of time and distance along the fracture length. 10 refs., 2 tabs., 16 figs., 1 appendix.

Identification tibia and fibula bone fracture location using scanline algorithm

Science.gov (United States)

Muchtar, M. A.; Simanjuntak, S. E.; Rahmat, R. F.; Mawengkang, H.; Zarlis, M.; Sitompul, O. S.; Winanto, I. D.; Andayani, U.; Syahputra, M. F.; Siregar, I.; Nasution, T. H.

2018-03-01

Fracture is a condition that there is a damage in the continuity of the bone, usually caused by stress, trauma or weak bones. The tibia and fibula are two separated-long bones in the lower leg, closely linked at the knee and ankle. Tibia/fibula fracture often happen when there is too much force applied to the bone that it can withstand. One of the way to identify the location of tibia/fibula fracture is to read X-ray image manually. Visual examination requires more time and allows for errors in identification due to the noise in image. In addition, reading X-ray needs highlighting background to make the objects in X-ray image appear more clearly. Therefore, a method is required to help radiologist to identify the location of tibia/fibula fracture. We propose some image-processing techniques for processing cruris image and Scan line algorithm for the identification of fracture location. The result shows that our proposed method is able to identify it and reach up to 87.5% of accuracy.

Bimalleolar ankle fracture with proximal fibular fracture

NARCIS (Netherlands)

Colenbrander, R. J.; Struijs, P. A. A.; Ultee, J. M.

2005-01-01

A 56-year-old female patient suffered a bimalleolar ankle fracture with an additional proximal fibular fracture. This is an unusual fracture type, seldom reported in literature. It was operatively treated by open reduction and internal fixation of the lateral malleolar fracture. The proximal fibular

Correlation of Hip Fracture with Other Fracture Types: Toward a Rational Composite Hip Fracture Endpoint

Science.gov (United States)

Colón-Emeric, Cathleen; Pieper, Carl F.; Grubber, Janet; Van Scoyoc, Lynn; Schnell, Merritt L; Van Houtven, Courtney Harold; Pearson, Megan; Lafleur, Joanne; Lyles, Kenneth W.; Adler, Robert A.

2016-01-01

Purpose With ethical requirements to the enrollment of lower risk subjects, osteoporosis trials are underpowered to detect reduction in hip fractures. Different skeletal sites have different levels of fracture risk and response to treatment. We sought to identify fracture sites which cluster with hip fracture at higher than expected frequency; if these sites respond to treatment similarly, then a composite fracture endpoint could provide a better estimate of hip fracture reduction. Methods Cohort study using Veterans Affairs and Medicare administrative data. Male Veterans (n=5,036,536) aged 50-99 years receiving VA primary care between1999-2009 were included. Fractures were ascertained using ICD9 and CPT codes and classified by skeletal site. Pearson correlation coefficients, logistic regression and kappa statistics, were used to describe the correlation between each fracture type and hip fracture within individuals, without regards to the timing of the events. Results 595,579 (11.8%) men suffered 1 or more fractures and 179,597 (3.6%) suffered 2 or more fractures during the time under study. Of those with one or more fractures, rib was the most common site (29%), followed by spine (22%), hip (21%) and femur (20%). The fracture types most highly correlated with hip fracture were pelvic/acetabular (Pearson correlation coefficient 0.25, p<0.0001), femur (0.15, p<0.0001), and shoulder (0.11, p<0.0001). Conclusions Pelvic, acetabular, femur, and shoulder fractures cluster with hip fractures within individuals at greater than expected frequency. If we observe similar treatment risk reductions within that cluster, subsequent trials could consider use of a composite endpoint to better estimate hip fracture risk. PMID:26151123

Diagnosing displaced four-part fractures of the proximal humerus: a review of observer studies

DEFF Research Database (Denmark)

Brorson, Stig; Bagger, Jens; Sylvest, Annette

2009-01-01

Displaced four-part fractures comprise 2-10 % of all proximal humeral fractures. The optimal treatment is unclear and randomised trials are needed. The conduct and interpretation of such trials is facilitated by a reproducible fracture classification. We aimed at quantifying observer agreement...... on the classification of displaced four-part fractures according to the Neer system. Published and unpublished data from five observer studies were reviewed. Observers agreed less on displaced four-part fractures than on the overall Neer classification. Mean kappa values for interobserver agreement ranged from 0.......16 to 0.48. Specialists agreed slightly more than fellows and residents. Advanced imaging modalities (CT and 3D CT) seemed to contribute more to classification of displaced four-part patterns than in less complex fracture patterns. Low observer agreement may challenge the clinical approach to displaced...

On-line Optimization-Based Simulators for Fractured and Non-fractured Reservoirs

Energy Technology Data Exchange (ETDEWEB)

Milind D. Deo

2005-08-31

Oil field development is a multi-million dollar business. Reservoir simulation is often used to guide the field management and development process. Reservoir characterization and geologic modeling tools have become increasingly sophisticated. As a result the geologic models produced are complex. Most reservoirs are fractured to a certain extent. The new geologic characterization methods are making it possible to map features such as faults and fractures, field-wide. Significant progress has been made in being able to predict properties of the faults and of the fractured zones. Traditionally, finite difference methods have been employed in discretizing the domains created by geologic means. For complex geometries, finite-element methods of discretization may be more suitable. Since reservoir simulation is a mature science, some of the advances in numerical methods (linear, nonlinear solvers and parallel computing) have not been fully realized in the implementation of most of the simulators. The purpose of this project was to address some of these issues. {sm_bullet} One of the goals of this project was to develop a series of finite-element simulators to handle problems of complex geometry, including systems containing faults and fractures. {sm_bullet} The idea was to incorporate the most modern computing tools; use of modular object-oriented computer languages, the most sophisticated linear and nonlinear solvers, parallel computing methods and good visualization tools. {sm_bullet} One of the tasks of the project was also to demonstrate the construction of fractures and faults in a reservoir using the available data and to assign properties to these features. {sm_bullet} Once the reservoir model is in place, it is desirable to find the operating conditions, which would provide the best reservoir performance. This can be accomplished by utilization optimization tools and coupling them with reservoir simulation. Optimization-based reservoir simulation was one of the

Low volumetric BMD is linked to upper-limb fracture in pubertal girls and persists into adulthood: a seven-year cohort study.

Science.gov (United States)

Cheng, Sulin; Xu, Leiting; Nicholson, Patrick H F; Tylavsky, Frances; Lyytikäinen, Arja; Wang, Qingju; Suominen, Harri; Kujala, Urho M; Kröger, Heikki; Alen, Markku

2009-09-01

The aetiology of increased incidence of fracture during puberty is unclear. This study aimed to determine whether low volumetric bone mineral density (vBMD) in the distal radius is associated with upper-limb fractures in growing girls, and whether any such vBMD deficit persists into adulthood. Fracture history from birth to 20 years was obtained and verified by medical records in 1034 Finnish girls aged 10-13 years. Bone density and geometry at distal radius, biomarkers and lifestyle/behavioural factors were assessed in a subset of 396 girls with a 7.5-year follow-up. We found that fracture incidence peaked during puberty (relative risk 3.1 at age of 8-14 years compared to outside this age window), and 38% of fractures were in the upper-limb. Compared to the non-fracture cohort, girls who sustained upper-limb fracture at ages 8-14 years had lower distal radial vBMD at baseline (258.9+/-37.5 vs. 287.5+/-34.1 mg/cm(3), p=0.001), 1-year (252.0+/-29.3 vs. 282.6+/-33.5 mg/cm(3), p=0.001), 2-year (258.9+/-32.2 vs. 289.9+/-40.1 mg/cm(3), p=0.003), and 7-year follow-ups (early adulthood, 307.6+/-35.9 vs. 343.6+/-40.9 mg/cm(3), p=0.002). There was a consistent trend towards larger bone cross-sectional area in the fracture cohort compared to non-fracture. In a logistic regression model, lower vBMD (p=0.001) was the only significant predictor of upper-limb fracture during the period of 8-14 years. Our results indicate that low BMD is an important factor underlying elevated upper-limb fracture risk during puberty, and that low BMD in pubertal girls with fracture persists into adulthood. Hence low vBMD during childhood is not a transient deficit. Methods to monitor vBMD and to maximise bone mineral accrual and reduce risks of falling in childhood should be developed.

A Review of Periprosthetic Femoral Fractures Associated With Total Hip Arthroplasty

Science.gov (United States)

Marsland, Daniel; Mears, Simon C.

2012-01-01

Periprosthetic fractures of the femur in association with total hip arthroplasty are increasingly common and often difficult to treat. Patients with periprosthetic fractures are typically elderly and frail and have osteoporosis. No clear consensus exists regarding the optimal management strategy because there is limited high-quality research. The Vancouver classification facilitates treatment decisions. In the presence of a stable prosthesis (type-B1 and -C fractures), most authors recommend surgical stabilization of the fracture with plates, strut grafts, or a combination thereof. In up to 20% of apparent Vancouver type-B1 fractures, the femoral stem is loose, which may explain the high failure rates associated with open reduction and internal fixation. Some authors recommend routine opening and dislocation of the hip to perform an intraoperative stem stability test to rule out a loose component. Advances in plating techniques and technology are improving the outcomes for these fractures. For fractures around a loose femoral prosthesis (types B2 and 3), revision using an extensively porous-coated uncemented long stem, with or without additional fracture fixation, appears to offer the most reliable outcome. Cement-in-cement revision using a long-stem prosthesis is feasible in elderly patients with a well-fixed cement mantle. It is essential to treat the osteoporosis to help fracture healing and to prevent further fractures. We provide an overview of the causes, classification, and management of periprosthetic femoral fractures around a total hip arthroplasty based on the current best available evidence. PMID:23569704

Elastic-plastic fracture mechanics of compact bone

Science.gov (United States)

Yan, Jiahau

Bone is a composite composed mainly of organics, minerals and water. Most studies on the fracture toughness of bone have been conducted at room temperature. Considering that the body temperature of animals is higher than room temperature, and that bone has a high volumetric percentage of organics (generally, 35--50%), the effect of temperature on fracture toughness of bone should be studied. Single-edged V-shaped notched (SEVN) specimens were prepared to measure the fracture toughness of bovine femur and manatee rib in water at 0, 10, 23, 37 and 50°C. The fracture toughness of bovine femur and manatee rib were found to decrease from 7.0 to 4.3 MPa·m1/2 and from 5.5 to 4.1 MPa·m1/2, respectively, over a temperature range of 50°C. The decreases were attributed to inability of the organics to sustain greater stresses at higher temperatures. We studied the effects of water and organics on fracture toughness of bone using water-free and organics-free SEVN specimens at 23°C. Water-free and organics-free specimens were obtained by placing fresh bone specimen in a furnace at different temperatures. Water and organics significantly affected the fracture toughness of bone. Fracture toughness of the water-free specimens was 44.7% (bovine femur) and 32.4% (manatee rib) less than that of fresh-bone specimens. Fracture toughness of the organics-free specimens was 92.7% (bovine femur) and 91.5% (manatee rib) less than that of fresh bone specimens. Linear Elastic Fracture Mechanics (LEFM) is widely used to study bone. However, bone often has small to moderate scale yielding during testing. We used J integral, an elastic-plastic fracture-mechanics parameter, to study the fracture process of bone. The J integral of bovine femur increased from 6.3 KJ/mm2 at 23°C to 6.7 KJ/mm2 at 37°C. Although the fracture toughness of bovine bone decreases as the temperature increases, the J integral results show a contrary trend. The energy spent in advancing the crack beyond the linear

Comparison of circummandibular wiring with resorbable bone plates in pediatric mandibular fractures.

Science.gov (United States)

Saikrishna, D; Gupta, Nimish

2010-06-01

Pediatric patients present a unique challenge to maxillofacial surgeons in terms of their treatment planning as well as in their functional and nutritional needs which are different from that of adult patients. Early literature has advocated conservative closed management of pediatric fractures to prevent complications. However recent advances in maxillofacial surgery has enabled us to use biodegradable plates and screws, which overcomes the limitations of metallic plates. We present a comparison of two cases of parasymphysis fracture treated with circum-mandibular wiring and biodegradable plate fixation their outcome in terms of fracture healing and functional stability.

Foal Fractures: Osteochondral Fragmentation, Proximal Sesamoid Bone Fractures/Sesamoiditis, and Distal Phalanx Fractures.

Science.gov (United States)

Reesink, Heidi L

2017-08-01

Foals are susceptible to many of the same types of fractures as adult horses, often secondary to external sources of trauma. In addition, some types of fractures are specific to foals and occur routinely in horses under 1 year of age. These foal-specific fractures may be due to the unique musculoskeletal properties of the developing animal and may present with distinct clinical signs. Treatment plans and prognoses are tailored specifically to young animals. Common fractures not affecting the long bones in foals are discussed in this article, including osteochondral fragmentation, proximal sesamoid bone fractures/sesamoiditis, and distal phalanx fractures. Copyright © 2017 Elsevier Inc. All rights reserved.

Effect of Control Mode and Test Rate on the Measured Fracture Toughness of Advanced Ceramics

Science.gov (United States)

Hausmann, Bronson D.; Salem, Jonathan A.

2018-01-01

The effects of control mode and test rate on the measured fracture toughness of ceramics were evaluated by using chevron-notched flexure specimens in accordance with ASTM C1421. The use of stroke control gave consistent results with about 2% (statistically insignificant) variation in measured fracture toughness for a very wide range of rates (0.005 to 0.5 mm/min). Use of strain or crack mouth opening displacement (CMOD) control gave approx. 5% (statistically significant) variation over a very wide range of rates (1 to 80 µm/m/s), with the measurements being a function of rate. However, the rate effect was eliminated by use of dry nitrogen, implying a stress corrosion effect rather than a stability effect. With the use of a nitrogen environment during strain controlled tests, fracture toughness values were within about 1% over a wide range of rates (1 to 80 micons/m/s). CMOD or strain control did allow stable crack extension well past maximum force, and thus is preferred for energy calculations. The effort is being used to confirm recommendations in ASTM Test Method C1421 on fracture toughness measurement.

Risk Factors for Pelvic Insufficiency Fractures in Locally Advanced Cervical Cancer Following Intensity Modulated Radiation Therapy

Energy Technology Data Exchange (ETDEWEB)

Ramlov, Anne, E-mail: anraml@rm.dk [Department of Oncology, Aarhus University Hospital, Aarhus (Denmark); Pedersen, Erik Morre; Røhl, Lisbeth [Department of Radiotherapy, Aarhus University Hospital, Aarhus (Denmark); Worm, Esben [Department of Medical Physics, Aarhus University Hospital, Aarhus (Denmark); Fokdal, Lars; Lindegaard, Jacob Chr. [Department of Oncology, Aarhus University Hospital, Aarhus (Denmark); Tanderup, Kari [Department of Oncology, Aarhus University Hospital, Aarhus (Denmark); Department of Medical Physics, Aarhus University Hospital, Aarhus (Denmark)

2017-04-01

Purpose: To investigate the incidence of and risk factors for pelvic insufficiency fracture (PIF) after definitive chemoradiation therapy for locally advanced cervical cancer (LACC). Methods and Materials: We analyzed 101 patients with LACC treated from 2008-2014. Patients received weekly cisplatin and underwent external beam radiation therapy with 45 Gy in 25 fractions (node-negative patients) or 50 Gy in 25 fractions with a simultaneous integrated boost of 60 Gy in 30 fractions (node-positive patients). Pulsed dose rate magnetic resonance imaging guided adaptive brachytherapy was given in addition. Follow-up magnetic resonance imaging was performed routinely at 3 and 12 months after the end of treatment or based on clinical indication. PIF was defined as a fracture line with or without sclerotic changes in the pelvic bones. D{sub 50%} and V{sub 55Gy} were calculated for the os sacrum and jointly for the os ileum and pubis. Patient- and treatment-related factors including dose were analyzed for correlation with PIF. Results: The median follow-up period was 25 months. The median age was 50 years. In 20 patients (20%), a median of 2 PIFs (range, 1-3 PIFs) were diagnosed; half were asymptomatic. The majority of the fractures were located in the sacrum (77%). Age was a significant risk factor (P<.001), and the incidence of PIF was 4% and 37% in patients aged ≤50 years and patients aged >50 years, respectively. Sacrum D{sub 50%} was a significant risk factor in patients aged >50 years (P=.04), whereas V{sub 55Gy} of the sacrum and V{sub 55Gy} of the pelvic bones were insignificant (P=.33 and P=.18, respectively). A dose-effect curve for sacrum D{sub 50%} in patients aged >50 years showed that reduction of sacrum D{sub 50%} from 40 Gy{sub EQD2} to 35 Gy{sub EQD2} reduces PIF risk from 45% to 22%. Conclusions: PIF is common after treatment of LACC and is mainly seen in patients aged >50 years. Our data indicate that PIFs are not related to lymph node

Risk factors for fragility fracture in Seremban district, Malaysia: a comparison of patients with fragility fracture in the orthopedic ward versus those in the outpatient department.

Science.gov (United States)

Keng Yin Loh; King Hock Shong; Soo Nie Lan; Lo, Wan-Yi; Shu Yuen Woon

2008-01-01

Osteoporosis is a silent disease and becomes clinically significant in the presence of fragility fracture. Identifying risk factors that are associated with osteoporosis in the community is important in reducing the incidence of fragility fracture. The aim of this study is to identify risk factors associated with fragility fracture in the Seremban District of Malaysia. This is a population comparison study between orthopedic ward patients and outpatients attending a community health clinic for 6 months. Epidemiological data and the possible risk factors for osteoporosis were collected by direct interview. This study demonstrates that advancing age, low body weight, smoking, lack of regular exercise, low consumption of calcium containing foods, and using bone depleting drugs (steroids, thyroid hormone, and frusemides) are major risk factors for fragility fracture. Most of these risk factors are modifiable through effective lifestyle intervention.

Fatigue and fracture: Overview

Science.gov (United States)

Halford, G. R.

1984-01-01

A brief overview of the status of the fatigue and fracture programs is given. The programs involve the development of appropriate analytic material behavior models for cyclic stress-strain-temperature-time/cyclic crack initiation, and cyclic crack propagation. The underlying thrust of these programs is the development and verification of workable engineering methods for the calculation, in advance of service, of the local cyclic stress-strain response at the critical life governing location in hot section compounds, and the resultant crack initiation and crack growth lifetimes.

The Tribology of Explanted Hip Resurfacings Following Early Fracture of the Femur.

Science.gov (United States)

Lord, James K; Langton, David J; Nargol, Antoni V F; Meek, R M Dominic; Joyce, Thomas J

2015-10-15

A recognized issue related to metal-on-metal hip resurfacings is early fracture of the femur. Most theories regarding the cause of fracture relate to clinical factors but an engineering analysis of failed hip resurfacings has not previously been reported. The objective of this work was to determine the wear volumes and surface roughness values of a cohort of retrieved hip resurfacings which were removed due to early femoral fracture, infection and avascular necrosis (AVN). Nine resurfacing femoral heads were obtained following early fracture of the femur, a further five were retrieved due to infection and AVN. All fourteen were measured for volumetric wear using a co-ordinate measuring machine. Wear rates were then calculated and regions of the articulating surface were divided into "worn" and "unworn". Roughness values in these regions were measured using a non-contacting profilometer. The mean time to fracture was 3.7 months compared with 44.4 months for retrieval due to infection and AVN. Average wear rates in the early fracture heads were 64 times greater than those in the infection and AVN retrievals. Given the high wear rates of the early fracture components, such wear may be linked to an increased risk of femoral neck fracture.

The Tribology of Explanted Hip Resurfacings Following Early Fracture of the Femur

Directory of Open Access Journals (Sweden)

James K. Lord

2015-10-01

Full Text Available A recognized issue related to metal-on-metal hip resurfacings is early fracture of the femur. Most theories regarding the cause of fracture relate to clinical factors but an engineering analysis of failed hip resurfacings has not previously been reported. The objective of this work was to determine the wear volumes and surface roughness values of a cohort of retrieved hip resurfacings which were removed due to early femoral fracture, infection and avascular necrosis (AVN. Nine resurfacing femoral heads were obtained following early fracture of the femur, a further five were retrieved due to infection and AVN. All fourteen were measured for volumetric wear using a co-ordinate measuring machine. Wear rates were then calculated and regions of the articulating surface were divided into “worn” and “unworn”. Roughness values in these regions were measured using a non-contacting profilometer. The mean time to fracture was 3.7 months compared with 44.4 months for retrieval due to infection and AVN. Average wear rates in the early fracture heads were 64 times greater than those in the infection and AVN retrievals. Given the high wear rates of the early fracture components, such wear may be linked to an increased risk of femoral neck fracture.

The motion of a redox front in a system of bentonite and rock, incorporating fracture transport effects

International Nuclear Information System (INIS)

Shaw, W.; Robinson, P.

1992-02-01

This report presents new calculations of the motion of a redox front in a system of bentonite and fractured rock, incorporation advection and diffusion of oxidants in fracture water. The results reported here have been incorporated into preliminary base case calculations using the source term model CALIBRE. The model presented here differs mainly in its treatment of the effects of the fracture. Previously, a 'zero-concentration' boundary condition was applied, and this resulted in retardation of the front near the fracture. When a more detailed advection-diffusion model is applied, the front is advanced in a neighbourhood of the fracture. (25 refs.) (au)

Linked data management

CERN Document Server

Hose, Katja; Schenkel, Ralf

2014-01-01

Linked Data Management presents techniques for querying and managing Linked Data that is available on today’s Web. The book shows how the abundance of Linked Data can serve as fertile ground for research and commercial applications. The text focuses on aspects of managing large-scale collections of Linked Data. It offers a detailed introduction to Linked Data and related standards, including the main principles distinguishing Linked Data from standard database technology. Chapters also describe how to generate links between datasets and explain the overall architecture of data integration systems based on Linked Data. A large part of the text is devoted to query processing in different setups. After presenting methods to publish relational data as Linked Data and efficient centralized processing, the book explores lookup-based, distributed, and parallel solutions. It then addresses advanced topics, such as reasoning, and discusses work related to read-write Linked Data for system interoperation. Desp...

Streaming Potential Modeling to Understand the Identification of Hydraulically Active Fractures and Fracture-Matrix Fluid Interactions Using the Self-Potential Method

Science.gov (United States)

Jougnot, D.; Roubinet, D.; Linde, N.; Irving, J.

2016-12-01

Quantifying fluid flow in fractured media is a critical challenge in a wide variety of research fields and applications. To this end, geophysics offers a variety of tools that can provide important information on subsurface physical properties in a noninvasive manner. Most geophysical techniques infer fluid flow by data or model differencing in time or space (i.e., they are not directly sensitive to flow occurring at the time of the measurements). An exception is the self-potential (SP) method. When water flows in the subsurface, an excess of charge in the pore water that counterbalances electric charges at the mineral-pore water interface gives rise to a streaming current and an associated streaming potential. The latter can be measured with the SP technique, meaning that the method is directly sensitive to fluid flow. Whereas numerous field experiments suggest that the SP method may allow for the detection of hydraulically active fractures, suitable tools for numerically modeling streaming potentials in fractured media do not exist. Here, we present a highly efficient two-dimensional discrete-dual-porosity approach for solving the fluid-flow and associated self-potential problems in fractured domains. Our approach is specifically designed for complex fracture networks that cannot be investigated using standard numerical methods due to computational limitations. We then simulate SP signals associated with pumping conditions for a number of examples to show that (i) accounting for matrix fluid flow is essential for accurate SP modeling and (ii) the sensitivity of SP to hydraulically active fractures is intimately linked with fracture-matrix fluid interactions. This implies that fractures associated with strong SP amplitudes are likely to be hydraulically conductive, attracting fluid flow from the surrounding matrix.

Biomimetic strategies for fracture repair: engineering the cell microenvironment for directed tissue formation

OpenAIRE

Vas, Wollis J.; Shah, Mittal; Al Hosni, Rawiya; Owen, Helen C.; Roberts, Scott J.

2017-01-01

Complications resulting from impaired fracture healing have major clinical implications on fracture management strategies. Novel concepts taken from developmental biology have driven research strategies towards the elaboration of regenerative approaches that can truly harness the complex cellular events involved in tissue formation and repair. Advances in polymer technology and a better understanding of naturally derived scaffolds have given rise to novel biomaterials with an increasing abili...

Rib fractures in chronic alcoholic men: Relationship with feeding habits, social problems, malnutrition, bone alterations, and liver dysfunction.

Science.gov (United States)

González-Reimers, Emilio; García-Valdecasas-Campelo, Elena; Santolaria-Fernández, Francisco; Milena-Abril, Antonio; Rodríguez-Rodríguez, Eva; Martínez-Riera, Antonio; Pérez-Ramírez, Alina; Alemán-Valls, María Remedios

2005-10-01

Rib fractures are common in alcoholics. This high prevalence might be due to ethanol-associated malnutrition, bone disease, liver dysfunction, or the peculiar lifestyle of the alcoholic with frequent trauma and altercations. In this study we try to discern the role of these factors on rib fracture (assessed on a plain thoracic X-ray film) in 81 consecutive alcoholic patients, 25 of them cirrhotics. Serum albumin, prothrombin aspartate aminotransferase (ASAT), alanine aminotransferase (ALAT), gamma-glutamyl transpeptidase, C-terminal cross-linking telopeptide of type 1 collagen, osteocalcin, insulin growth factor 1, 1,25-dihydroxyvitamin D, parathyroid hormone, estradiol, free testosterone, and corticosterone were measured, and the patients also underwent assessment of bone mineral density by a HOLOGIC QDR-2000 bone densitometer (Waltham, MA, USA). Body mass index, triceps skinfold, and brachial perimeter were also determined, and the patients and their families were asked about tobacco consumption, social and familial links, consumption of ethanol by other members of the family, kind of job, and feeding habits. Forty-two male nondrinker sanitary workers of similar age served as controls. Forty of the 81 patients showed rib fractures. There was a statistically significant association between rib fractures and disruption of social and familial links, irregular feeding habits (in bars or pubs, not at home), ethanol consumption by close relatives, and intensity of tobacco consumption, but not between rib fractures and liver function tests, nutritional parameters, or bone mineral density, besides a nearly significant trend (p = .053) with the presence of osteopenia at the femoral neck. Patients with major withdrawal symptoms at admission also presented more frequent rib fractures. We conclude that rib fractures in alcoholics are related to the peculiar lifestyle of these patients rather than to bone alterations, liver dysfunction, or nutritional status.

Associations of early premenopausal fractures with subsequent fractures vary by sites and mechanisms of fractures.

Science.gov (United States)

Honkanen, R; Tuppurainen, M; Kroger, H; Alhava, E; Puntila, E

1997-04-01

In a retrospective population-based study we assessed whether and how self-reported former fractures sustained at the ages of 20-34 are associated with subsequent fractures sustained at the ages of 35-57. The 12,162 women who responded to fracture questions of the baseline postal enquiry (in 1989) of the Kuopio Osteoporosis Study, Finland formed the study population. They reported 589 former and 2092 subsequent fractures. The hazard ratio (HR), with 95% confidence interval (CI), of a subsequent fracture was 1.9 (1.6-2.3) in women with the history of a former fracture compared with women without such a history. A former low-energy wrist fracture was related to subsequent low-energy wrist [HR = 3.7 (2.0-6.8)] and high-energy nonwrist [HR = 2.4 (1.3-4.4)] fractures, whereas former high-energy nonwrist fractures were related only to subsequent high-energy nonwrist [HR = 2.8 (1.9-4.1)] but not to low-energy wrist [HR = 0.7 (0.3-1.8)] fractures. The analysis of bone mineral density (BMD) data of a subsample of premenopausal women who underwent dual x-ray absorptiometry (DXA) during 1989-91 revealed that those with a wrist fracture due to a fall on the same level at the age of 20-34 recorded 6.5% lower spinal (P = 0.140) and 10.5% lower femoral (P = 0.026) BMD than nonfractured women, whereas the corresponding differences for women with a former nonwrist fracture due to high-energy trauma were -1.8% (P = 0.721) and -2.4% (P = 0. 616), respectively. Our results suggest that an early premenopausal, low-energy wrist fracture is an indicator of low peak BMD which predisposes to subsequent fractures in general, whereas early high-energy fractures are mainly indicators of other and more specific extraskeletal factors which mainly predispose to same types of subsequent fractures only.

Visualization and Hierarchical Analysis of Flow in Discrete Fracture Network Models

Science.gov (United States)

Aldrich, G. A.; Gable, C. W.; Painter, S. L.; Makedonska, N.; Hamann, B.; Woodring, J.

2013-12-01

Flow and transport in low permeability fractured rock is primary in interconnected fracture networks. Prediction and characterization of flow and transport in fractured rock has important implications in underground repositories for hazardous materials (eg. nuclear and chemical waste), contaminant migration and remediation, groundwater resource management, and hydrocarbon extraction. We have developed methods to explicitly model flow in discrete fracture networks and track flow paths using passive particle tracking algorithms. Visualization and analysis of particle trajectory through the fracture network is important to understanding fracture connectivity, flow patterns, potential contaminant pathways and fast paths through the network. However, occlusion due to the large number of highly tessellated and intersecting fracture polygons preclude the effective use of traditional visualization methods. We would also like quantitative analysis methods to characterize the trajectory of a large number of particle paths. We have solved these problems by defining a hierarchal flow network representing the topology of particle flow through the fracture network. This approach allows us to analyses the flow and the dynamics of the system as a whole. We are able to easily query the flow network, and use paint-and-link style framework to filter the fracture geometry and particle traces based on the flow analytics. This allows us to greatly reduce occlusion while emphasizing salient features such as the principal transport pathways. Examples are shown that demonstrate the methodology and highlight how use of this new method allows quantitative analysis and characterization of flow and transport in a number of representative fracture networks.

A Thermoelastic Hydraulic Fracture Design Tool for Geothermal Reservoir Development

Energy Technology Data Exchange (ETDEWEB)

Ahmad Ghassemi

2003-06-30

Geothermal energy is recovered by circulating water through heat exchange areas within a hot rock mass. Geothermal reservoir rock masses generally consist of igneous and metamorphic rocks that have low matrix permeability. Therefore, cracks and fractures play a significant role in extraction of geothermal energy by providing the major pathways for fluid flow and heat exchange. Thus, knowledge of conditions leading to formation of fractures and fracture networks is of paramount importance. Furthermore, in the absence of natural fractures or adequate connectivity, artificial fracture are created in the reservoir using hydraulic fracturing. At times, the practice aims to create a number of parallel fractures connecting a pair of wells. Multiple fractures are preferred because of the large size necessary when using only a single fracture. Although the basic idea is rather simple, hydraulic fracturing is a complex process involving interactions of high pressure fluid injections with a stressed hot rock mass, mechanical interaction of induced fractures with existing natural fractures, and the spatial and temporal variations of in-situ stress. As a result it is necessary to develop tools that can be used to study these interactions as an integral part of a comprehensive approach to geothermal reservoir development, particularly enhanced geothermal systems. In response to this need we have set out to develop advanced thermo-mechanical models for design of artificial fractures and rock fracture research in geothermal reservoirs. These models consider the significant hydraulic and thermo-mechanical processes and their interaction with the in-situ stress state. Wellbore failure and fracture initiation is studied using a model that fully couples poro-mechanical and thermo-mechanical effects. The fracture propagation model is based on a complex variable and regular displacement discontinuity formulations. In the complex variable approach the displacement discontinuities are

Hydraulic fracture monitoring in hard rock at 410 m depth with an advanced fluid-injection protocol and extensive sensor array

Science.gov (United States)

Zang, Arno; Stephansson, Ove; Stenberg, Leif; Plenkers, Katrin; Specht, Sebastian; Milkereit, Claus; Schill, Eva; Kwiatek, Grzegorz; Dresen, Georg; Zimmermann, Günter; Dahm, Torsten; Weber, Michael

2017-02-01

In this paper, an underground experiment at the Äspö Hard Rock Laboratory (HRL) is described. Main goal is optimizing geothermal heat exchange in crystalline rock mass at depth by multistage hydraulic fracturing with minimal impact on the environment, that is, seismic events. For this, three arrays with acoustic emission, microseismicity and electromagnetic sensors are installed mapping hydraulic fracture initiation and growth. Fractures are driven by three different water injection schemes (continuous, progressive and pulse pressurization). After a brief review of hydraulic fracture operations in crystalline rock mass at mine scale, the site geology and the stress conditions at Äspö HRL are described. Then, the continuous, single-flow rate and alternative, multiple-flow rate fracture breakdown tests in a horizontal borehole at depth level 410 m are described together with the monitoring networks and sensitivity. Monitoring results include the primary catalogue of acoustic emission hypocentres obtained from four hydraulic fractures with the in situ trigger and localizing network. The continuous versus alternative water injection schemes are discussed in terms of the fracture breakdown pressure, the fracture pattern from impression packer result and the monitoring at the arrays. An example of multistage hydraulic fracturing with several phases of opening and closing of fracture walls is evaluated using data from acoustic emissions, seismic broad-band recordings and electromagnetic signal response. Based on our limited amount of in situ tests (six) and evaluation of three tests in Ävrö granodiorite, in the multiple-flow rate test with progressively increasing target pressure, the acoustic emission activity starts at a later stage in the fracturing process compared to the conventional fracturing case with continuous water injection. In tendency, also the total number and magnitude of acoustic events are found to be smaller in the progressive treatment with

Intra-articular Physeal Fractures of the Distal Femur: A Frequently Missed Diagnosis in Adolescent Athletes.

Science.gov (United States)

Pennock, Andrew T; Ellis, Henry B; Willimon, Samuel C; Wyatt, Charles; Broida, Samuel E; Dennis, M Morgan; Bastrom, Tracey

2017-10-01

Intra-articular physeal fractures of the distal femur are an uncommon injury pattern, with only a few small case series reported in the literature. To pool patients from 3 high-volume pediatric centers to better understand this injury pattern, to determine outcomes of surgical treatment, and to assess risk factors for complications. Case series; Level of evidence, 4. A multicenter retrospective review of all patients presenting with an intra-articular physeal fracture between 2006 and 2016 was performed. Patient demographic and injury data, surgical data, and postoperative outcomes were documented. Radiographs were evaluated for fracture classification (Salter-Harris), location, and displacement. Differences between patients with and without complications were compared by use of analysis of variance or chi-square tests. A total of 49 patients, with a mean age of 13.5 years (range, 7-17 years), met the inclusion criteria. The majority of fractures were Salter-Harris type III fractures (84%) involving the medial femoral condyle (88%). Football was responsible for 50% of the injuries. The initial diagnosis was missed in 39% of cases, and advanced imaging showed greater mean displacement (6 mm) compared with radiographs (3 mm). All patients underwent surgery and returned to sport with "good to excellent" results after 2 years. Complications were more common in patients with wide-open growth plates, patients with fractures involving the lateral femoral condyle, and patients who were casted ( P < .05). Clinicians evaluating skeletally immature athletes (particularly football players) with acute knee injuries should maintain a high index of suspicion for an intra-articular physeal fracture. These fractures are frequently missed, and advanced imaging may be required to establish the diagnosis. Leg-length discrepancies and angular deformities are not uncommon, and patients should be monitored closely. Surgical outcomes are good when fractures are identified, with high rates

Ballistic fractures: indirect fracture to bone.

Science.gov (United States)

Dougherty, Paul J; Sherman, Don; Dau, Nathan; Bir, Cynthia

2011-11-01

Two mechanisms of injury, the temporary cavity and the sonic wave, have been proposed to produce indirect fractures as a projectile passes nearby in tissue. The purpose of this study is to evaluate the temporal relationship of pressure waves using strain gauge technology and high-speed video to elucidate whether the sonic wave, the temporary cavity, or both are responsible for the formation of indirect fractures. Twenty-eight fresh frozen cadaveric diaphyseal tibia (2) and femurs (26) were implanted into ordnance gelatin blocks. Shots were fired using 9- and 5.56-mm bullets traversing through the gelatin only, passing close to the edge of the bone, but not touching, to produce an indirect fracture. High-speed video of the impact event was collected at 20,000 frames/s. Acquisition of the strain data were synchronized with the video at 20,000 Hz. The exact time of fracture was determined by analyzing and comparing the strain gauge output and video. Twenty-eight shots were fired, 2 with 9-mm bullets and 26 with 5.56-mm bullets. Eight indirect fractures that occurred were of a simple (oblique or wedge) pattern. Comparison of the average distance of the projectile from the bone was 9.68 mm (range, 3-20 mm) for fractured specimens and 15.15 mm (range, 7-28 mm) for nonfractured specimens (Student's t test, p = 0.036). In this study, indirect fractures were produced after passage of the projectile. Thus, the temporary cavity, not the sonic wave, was responsible for the indirect fractures.

Hydraulic fracture propagation modeling and data-based fracture identification

Science.gov (United States)

Zhou, Jing

Successful shale gas and tight oil production is enabled by the engineering innovation of horizontal drilling and hydraulic fracturing. Hydraulically induced fractures will most likely deviate from the bi-wing planar pattern and generate complex fracture networks due to mechanical interactions and reservoir heterogeneity, both of which render the conventional fracture simulators insufficient to characterize the fractured reservoir. Moreover, in reservoirs with ultra-low permeability, the natural fractures are widely distributed, which will result in hydraulic fractures branching and merging at the interface and consequently lead to the creation of more complex fracture networks. Thus, developing a reliable hydraulic fracturing simulator, including both mechanical interaction and fluid flow, is critical in maximizing hydrocarbon recovery and optimizing fracture/well design and completion strategy in multistage horizontal wells. A novel fully coupled reservoir flow and geomechanics model based on the dual-lattice system is developed to simulate multiple nonplanar fractures' propagation in both homogeneous and heterogeneous reservoirs with or without pre-existing natural fractures. Initiation, growth, and coalescence of the microcracks will lead to the generation of macroscopic fractures, which is explicitly mimicked by failure and removal of bonds between particles from the discrete element network. This physics-based modeling approach leads to realistic fracture patterns without using the empirical rock failure and fracture propagation criteria required in conventional continuum methods. Based on this model, a sensitivity study is performed to investigate the effects of perforation spacing, in-situ stress anisotropy, rock properties (Young's modulus, Poisson's ratio, and compressive strength), fluid properties, and natural fracture properties on hydraulic fracture propagation. In addition, since reservoirs are buried thousands of feet below the surface, the

A New Method to Infer Advancement of Saline Front in Coastal Groundwater Systems by 3D: The Case of Bari (Southern Italy Fractured Aquifer

Directory of Open Access Journals (Sweden)

Costantino Masciopinto

2016-02-01

Full Text Available A new method to study 3D saline front advancement in coastal fractured aquifers has been presented. Field groundwater salinity was measured in boreholes of the Bari (Southern Italy coastal aquifer with depth below water table. Then, the Ghyben-Herzberg freshwater/saltwater (50% sharp interface and saline front position were determined by model simulations of the freshwater flow in groundwater. Afterward, the best-fit procedure between groundwater salinity measurements, at assigned water depth of 1.0 m in boreholes, and distances of each borehole from the modelled freshwater/saltwater saline front was used to convert each position (x, y in groundwater to the water salinity concentration at depth of 1.0 m. Moreover, a second best-fit procedure was applied to the salinity measurements in boreholes with depth z. These results provided a grid file (x, y, z, salinity suitable for plotting the actual Bari aquifer salinity by 3D maps. Subsequently, in order to assess effects of pumping on the saltwater-freshwater transition zone in the coastal aquifer, the Navier-Stokes (N-S equations were applied to study transient density-driven flow and salt mass transport into freshwater of a single fracture. The rate of seawater/freshwater interface advancement given by the N-S solution was used to define the progression of saline front in Bari groundwater, starting from the actual salinity 3D map. The impact of pumping of 335 L·s−1 during the transition period of 112.8 days was easily highlighted on 3D salinity maps of Bari aquifer.

Retrospective evaluation and dating of non-accidental rib fractures in infants

International Nuclear Information System (INIS)

Sanchez, T.R.; Nguyen, H.; Palacios, W.; Doherty, M.; Coulter, K.

2013-01-01

Aim: To describe the sequential appearance of healing rib fractures on initial and follow-up radiographs using published guidelines in approximating the age of rib fractures in infants with the aim of establishing a more objective method of dating rib fractures by measuring the thickness of the callous formation. Materials and methods: This was a retrospective analysis of initial and follow-up digital skeletal surveys of infants less than 12 months of age performed between January 2008 and January 2012 at the University of California Davis Children's Hospital. Six radiological features of rib fractures evaluating the appearance of the callous formation (C stage) and fracture line (F stage) were assessed. Patients with osteogenesis imperfecta, known vitamin D deficiency, and skeletal or metabolic dysplasia were not included in the study. Thereafter, callous thickness was measured and recorded for each stage. Results: Sixteen infants (age range 1–11 months, seven males and nine females) with 23 rib fractures were analysed. The thickness of the callous formation follows a predictable pattern advancing one stage after a 2-week follow-up with progressive callous thickening starting from stage 2, peaks at around stage 4, and then tapers and remodels until it almost disappears when the fracture is healed at stage 6. Conclusion: It appears that rib fractures in infants follow a predictable pattern of healing. Measuring the thickness of the callous formation is a more objective way of guiding the radiologist in estimating the age of the fracture

Material Fracture Characterization and Toughness Improving Technology Developments

International Nuclear Information System (INIS)

Lee, Bong Sang; Kim, M. C.; Lee, H. J. and others

2005-04-01

Reactor pressure boundary components including pressure vessel and piping are facing a severe aging condition that can degrade the physical-mechanical properties under neutron irradiation, high temperature, high pressure, and corrosive environments. In order to increase the safety of nuclear power plants, it is inevitable to improve the credibility and capability of evaluation technology based on the quantitative fracture mechanics for aging assessment of reactor components. Irradiation embrittlement is the primary aging mechanism of reactor pressure vessel and various techniques have been developed to predict the aging characteristics by using only small volume of irradiated materials. Material database of the domestic structural steels for KSNP's under reactor environments must be very important to play a role in developing an advanced material, in improving the safety of nuclear components, and also in expanding the nuclear industry abroad. This research project has been focused on developing an advanced technology of testing and analysis in the fracture mechanical point of view as well as acquiring test data and improving the performance of nuclear structural steels

Fracture Propagation, Fluid Flow, and Geomechanics of Water-Based Hydraulic Fracturing in Shale Gas Systems and Electromagnetic Geophysical Monitoring of Fluid Migration

Energy Technology Data Exchange (ETDEWEB)

Kim, Jihoon; Um, Evan; Moridis, George

2014-12-01

We investigate fracture propagation induced by hydraulic fracturing with water injection, using numerical simulation. For rigorous, full 3D modeling, we employ a numerical method that can model failure resulting from tensile and shear stresses, dynamic nonlinear permeability, leak-off in all directions, and thermo-poro-mechanical effects with the double porosity approach. Our numerical results indicate that fracture propagation is not the same as propagation of the water front, because fracturing is governed by geomechanics, whereas water saturation is determined by fluid flow. At early times, the water saturation front is almost identical to the fracture tip, suggesting that the fracture is mostly filled with injected water. However, at late times, advance of the water front is retarded compared to fracture propagation, yielding a significant gap between the water front and the fracture top, which is filled with reservoir gas. We also find considerable leak-off of water to the reservoir. The inconsistency between the fracture volume and the volume of injected water cannot properly calculate the fracture length, when it is estimated based on the simple assumption that the fracture is fully saturated with injected water. As an example of flow-geomechanical responses, we identify pressure fluctuation under constant water injection, because hydraulic fracturing is itself a set of many failure processes, in which pressure consistently drops when failure occurs, but fluctuation decreases as the fracture length grows. We also study application of electromagnetic (EM) geophysical methods, because these methods are highly sensitive to changes in porosity and pore-fluid properties due to water injection into gas reservoirs. Employing a 3D finite-element EM geophysical simulator, we evaluate the sensitivity of the crosswell EM method for monitoring fluid movements in shaly reservoirs. For this sensitivity evaluation, reservoir models are generated through the coupled flow

Advances in coalbed methane reservoirs using integrated reservoir characterization and hydraulic fracturing in Karaganda coal basin, Kazakhstan

Science.gov (United States)

Ivakhnenko, Aleksandr; Aimukhan, Adina; Kenshimova, Aida; Mullagaliyev, Fandus; Akbarov, Erlan; Mullagaliyeva, Lylia; Kabirova, Svetlana; Almukhametov, Azamat

2017-04-01

Coalbed methane from Karaganda coal basin is considered to be an unconventional source of energy for the Central and Eastern parts of Kazakhstan. These regions are situated far away from the main traditional sources of oil and gas related to Precaspian petroleum basin. Coalbed methane fields in Karaganda coal basin are characterized by geological and structural complexity. Majority of production zones were characterized by high methane content and extremely low coal permeability. The coal reservoirs also contained a considerable natural system of primary, secondary, and tertiary fractures that were usually capable to accommodate passing fluid during hydraulic fracturing process. However, after closing was often observed coal formation damage including the loss of fluids, migration of fines and higher pressures required to treat formation than were expected. Unusual or less expected reservoir characteristics and values of properties of the coal reservoir might be the cause of the unusual occurred patterns in obtained fracturing, such as lithological peculiarities, rock mechanical properties and previous natural fracture systems in the coals. Based on these properties we found that during the drilling and fracturing of the coal-induced fractures have great sensitivity to complex reservoir lithology and stress profiles, as well as changes of those stresses. In order to have a successful program of hydraulic fracturing and avoid unnecessary fracturing anomalies we applied integrated reservoir characterization to monitor key parameters. In addition to logging data, core sample analysis was applied for coalbed methane reservoirs to observe dependence tiny lithological variations through the magnetic susceptibility values and their relation to permeability together with expected principal stress. The values of magnetic susceptibility were measured by the core logging sensor, which is equipped with the probe that provides volume magnetic susceptibility parameters

Distinguishing stress fractures from pathologic fractures: a multimodality approach

International Nuclear Information System (INIS)

Fayad, Laura M.; Kamel, Ihab R.; Kawamoto, Satomi; Bluemke, David A.; Fishman, Elliot K.; Frassica, Frank J.

2005-01-01

Whereas stress fractures occur in normal or metabolically weakened bones, pathologic fractures occur at the site of a bone tumor. Unfortunately, stress fractures may share imaging features with pathologic fractures on plain radiography, and therefore other modalities are commonly utilized to distinguish these entities. Additional cross-sectional imaging with CT or MRI as well as scintigraphy and PET scanning is often performed for further evaluation. For the detailed assessment of a fracture site, CT offers a high-resolution view of the bone cortex and periosteum which aids the diagnosis of a pathologic fracture. The character of underlying bone marrow patterns of destruction can also be ascertained along with evidence of a soft tissue mass. MRI, however, is a more sensitive technique for the detection of underlying bone marrow lesions at a fracture site. In addition, the surrounding soft tissues, including possible involvement of adjacent muscle, can be well evaluated with MRI. While bone scintigraphy and FDG-PET are not specific, they offer a whole-body screen for metastases in the case of a suspected malignant pathologic fracture. In this review, we present select examples of fractures that underscore imaging features that help distinguish stress fractures from pathologic fractures, since accurate differentiation of these entities is paramount. (orig.)

The advanced linked extended reconnaissance and targeting technology demonstration project

Science.gov (United States)

Cruickshank, James; de Villers, Yves; Maheux, Jean; Edwards, Mark; Gains, David; Rea, Terry; Banbury, Simon; Gauthier, Michelle

2007-06-01

The Advanced Linked Extended Reconnaissance & Targeting (ALERT) Technology Demonstration (TD) project is addressing key operational needs of the future Canadian Army's Surveillance and Reconnaissance forces by fusing multi-sensor and tactical data, developing automated processes, and integrating beyond line-of-sight sensing. We discuss concepts for displaying and fusing multi-sensor and tactical data within an Enhanced Operator Control Station (EOCS). The sensor data can originate from the Coyote's own visible-band and IR cameras, laser rangefinder, and ground-surveillance radar, as well as beyond line-of-sight systems such as a mini-UAV and unattended ground sensors. The authors address technical issues associated with the use of fully digital IR and day video cameras and discuss video-rate image processing developed to assist the operator to recognize poorly visible targets. Automatic target detection and recognition algorithms processing both IR and visible-band images have been investigated to draw the operator's attention to possible targets. The machine generated information display requirements are presented with the human factors engineering aspects of the user interface in this complex environment, with a view to establishing user trust in the automation. The paper concludes with a summary of achievements to date and steps to project completion.

A simple score for estimating the long-term risk of fracture in patients with multiple sclerosis

DEFF Research Database (Denmark)

Bazelier, M. T.; van Staa, T. P.; Uitdehaag, B. M. J.

2012-01-01

was converted into integer risk scores. Results: In comparison with the FRAX calculator, our risk score contains several new risk factors that have been linked with fracture, which include MS, use of antidepressants, use of anticonvulsants, history of falling, and history of fatigue. We estimated the 5- and 10......Objective: To derive a simple score for estimating the long-term risk of osteoporotic and hip fracture in individual patients with MS. Methods: Using the UK General Practice Research Database linked to the National Hospital Registry (1997-2008), we identified patients with incident MS (n = 5......,494). They were matched 1:6 by year of birth, sex, and practice with patients without MS (control subjects). Cox proportional hazards models were used to calculate the long-term risk of osteoporotic and hip fracture. We fitted the regression model with general and specific risk factors, and the final Cox model...

Double segmental tibial fractures - an unusual fracture pattern

Directory of Open Access Journals (Sweden)

Bali Kamal

2012-02-01

Full Text Available 【Abstract】A case of a 50-year-old pedestrian who was hit by a bike and suffered fractures of both bones of his right leg was presented. Complete clinical and radiographic assessment showed double segmental fractures of the tibia and multisegmental fractures of the fibula. Review of the literature revealed that this fracture pattern was unique and only a single case was reported so far. Moreover, we discussed the possible mechanisms which can lead to such an injury. We also discussed the management of segmental tibial fracture and the difficulties encountered with them. This case was managed by modern osteosynthesis tech- nique with a pleasing outcome. Key words: Fracture, bone; Tibia; Fibula; Nails

Adaptive Multiscale Modeling of Geochemical Impacts on Fracture Evolution

Science.gov (United States)

Molins, S.; Trebotich, D.; Steefel, C. I.; Deng, H.

2016-12-01

Understanding fracture evolution is essential for many subsurface energy applications, including subsurface storage, shale gas production, fracking, CO2 sequestration, and geothermal energy extraction. Geochemical processes in particular play a significant role in the evolution of fractures through dissolution-driven widening, fines migration, and/or fracture sealing due to precipitation. One obstacle to understanding and exploiting geochemical fracture evolution is that it is a multiscale process. However, current geochemical modeling of fractures cannot capture this multi-scale nature of geochemical and mechanical impacts on fracture evolution, and is limited to either a continuum or pore-scale representation. Conventional continuum-scale models treat fractures as preferential flow paths, with their permeability evolving as a function (often, a cubic law) of the fracture aperture. This approach has the limitation that it oversimplifies flow within the fracture in its omission of pore scale effects while also assuming well-mixed conditions. More recently, pore-scale models along with advanced characterization techniques have allowed for accurate simulations of flow and reactive transport within the pore space (Molins et al., 2014, 2015). However, these models, even with high performance computing, are currently limited in their ability to treat tractable domain sizes (Steefel et al., 2013). Thus, there is a critical need to develop an adaptive modeling capability that can account for separate properties and processes, emergent and otherwise, in the fracture and the rock matrix at different spatial scales. Here we present an adaptive modeling capability that treats geochemical impacts on fracture evolution within a single multiscale framework. Model development makes use of the high performance simulation capability, Chombo-Crunch, leveraged by high resolution characterization and experiments. The modeling framework is based on the adaptive capability in Chombo

Acetabular fractures following rugby tackles: a case series

LENUS (Irish Health Repository)

Good, Daniel W

2011-10-05

Abstract Introduction Rugby is the third most popular team contact sport in the world and is increasing in popularity. In 1995, rugby in Europe turned professional, and with this has come an increased rate of injury. Case presentation In a six-month period from July to December, two open reduction and internal fixations of acetabular fractures were performed in young Caucasian men (16 and 24 years old) who sustained their injuries after rugby tackles. Both of these cases are described as well as the biomechanical factors contributing to the fracture and the recovery. Acetabular fractures of the hip during sport are rare occurrences. Conclusion Our recent experience of two cases over a six-month period creates concern that these high-energy injuries may become more frequent as rugby continues to adopt advanced training regimens. Protective equipment is unlikely to reduce the forces imparted across the hip joint; however, limiting \\'the tackle\\' to only two players may well reduce the likelihood of this life-altering injury.

Audit, guidelines and standards: clinical governance for hip fracture care in Scotland.

Science.gov (United States)

Currie, Colin T; Hutchison, James D

To report on experience of national-level audit, guidelines and standards for hip fracture care in Scotland. Scottish Hip Fracture Audit (from 1993) documents case-mix, process and outcomes of hip fracture care in Scotland. Evidence-based national guidelines on hip fracture care are available (1997, updated 2002). Hip fracture serves as a tracer condition by the health quality assurance authority for its work on older people, which reported in 2004. Audit data are used locally to document care and support and monitor service developments. Synergy between the guidelines and the audit provides a means of improving care locally and monitoring care nationally. External review by the quality assurance body shows to what extent guideline-based standards relating to A&E care, pre-operative delay, multidisciplinary care and audit participation are met. Three national-level initiatives on hip fracture care have delivered: Reliable and large-scale comparative information on case-mix, care and outcomes; evidence-based recommendations on care; and nationally accountable standards inspected and reported by the national health quality assurance authority. These developments are linked and synergistic, and enjoy both clinical and managerial support. They provide an evolving framework for clinical governance, with casemix-adjusted outcome assessment for hip fracture care as a next step.

Association of Ipsilateral Rib Fractures With Displacement of Midshaft Clavicle Fractures.

Science.gov (United States)

Stahl, Daniel; Ellington, Matthew; Brennan, Kindyle; Brennan, Michael

2017-04-01

To determine whether the presence of ipsilateral rib fractures affects the rate of a clavicle fracture being unstable (>100% displacement). A retrospective review from 2002-2013 performed at a single level 1 trauma center evaluated 243 midshaft clavicle fractures. Single Level 1 trauma center. These fractures were subdivided into those with ipsilateral rib fractures (CIR; n = 149) and those without ipsilateral rib fractures (CnIR; n = 94). The amount of displacement was measured on the initial injury radiograph and subsequent follow-up radiographs. Fractures were classified into either 100% displacement, based on anteroposterior radiographs. Ipsilateral rib fractures were recorded based on which number rib was fractured and the total number of fractured ribs. One hundred sixteen (78%) of the CIR group and 51 (54%) of the CnIR group were found to have >100% displacement at follow-up (P = 0.0047). Seventy-two percent of the CIR group demonstrated progression from 100% displacement of the fracture compared with only 54% of the CnIR group (P fracture to >100% was 4.08 (P = 0.000194) when ribs 1-4 were fractured and not significant for rib fractures 5-8 or 9-12. The presence of concomitant ipsilateral rib fractures significantly increases the rate of midshaft clavicle fractures being >100% displaced. In addition, a fracture involving the upper one-third of the ribs significantly increases the rate of the clavicle fracture being >100% displaced on early follow-up. Clavicle fractures with associated ipsilateral rib fractures tend to demonstrate an increased amount of displacement on follow-up radiographs compared with those without ipsilateral rib fractures. Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Ceramic-on-ceramic bearing fractures in total hip arthroplasty: an analysis of data from the National Joint Registry.

Science.gov (United States)

Howard, D P; Wall, P D H; Fernandez, M A; Parsons, H; Howard, P W

2017-08-01

Ceramic-on-ceramic (CoC) bearings in total hip arthroplasty (THA) are commonly used, but concerns exist regarding ceramic fracture. This study aims to report the risk of revision for fracture of modern CoC bearings and identify factors that might influence this risk, using data from the National Joint Registry (NJR) for England, Wales, Northern Ireland and the Isle of Man. We analysed data on 223 362 bearings from 111 681 primary CoC THAs and 182 linked revisions for bearing fracture recorded in the NJR. We used implant codes to identify ceramic bearing composition and generated Kaplan-Meier estimates for implant survivorship. Logistic regression analyses were performed for implant size and patient specific variables to determine any associated risks for revision. A total of 222 852 bearings (99.8%) were CeramTec Biolox products. Revisions for fracture were linked to seven of 79 442 (0.009%) Biolox Delta heads, 38 of 31 982 (0.119%) Biolox Forte heads, 101 of 80 170 (0.126%) Biolox Delta liners and 35 of 31 258 (0.112%) Biolox Forte liners. Regression analysis of implant size revealed smaller heads had significantly higher odds of fracture (chi-squared 68.0, p ceramic type. Liner thickness was not predictive of fracture (p = 0.67). Body mass index (BMI) was independently associated with revision for both head fractures (odds ratio (OR) 1.09 per unit increase, p = 0.031) and liner fractures (OR 1.06 per unit increase, p = 0.006). We report the largest independent study of CoC bearing fractures to date. The risk of revision for CoC bearing fracture is very low but previous studies have underestimated this risk. There is good evidence that the latest generation of ceramic has greatly reduced the odds of head fracture but not of liner fracture. Small head size and high patient BMI are associated with an increased risk of ceramic bearing fracture. Cite this article: Bone Joint J 2017;99-B:1012-19. ©2017 The British Editorial Society of Bone & Joint Surgery.

Well test mathematical model for fractures network in tight oil reservoirs

Science.gov (United States)

Diwu, Pengxiang; Liu, Tongjing; Jiang, Baoyi; Wang, Rui; Yang, Peidie; Yang, Jiping; Wang, Zhaoming

2018-02-01

Well test, especially build-up test, has been applied widely in the development of tight oil reservoirs, since it is the only available low cost way to directly quantify flow ability and formation heterogeneity parameters. However, because of the fractures network near wellbore, generated from artificial fracturing linking up natural factures, traditional infinite and finite conductivity fracture models usually result in significantly deviation in field application. In this work, considering the random distribution of natural fractures, physical model of fractures network is proposed, and it shows a composite model feature in the large scale. Consequently, a nonhomogeneous composite mathematical model is established with threshold pressure gradient. To solve this model semi-analytically, we proposed a solution approach including Laplace transform and virtual argument Bessel function, and this method is verified by comparing with existing analytical solution. The matching data of typical type curves generated from semi-analytical solution indicates that the proposed physical and mathematical model can describe the type curves characteristic in typical tight oil reservoirs, which have up warping in late-term rather than parallel lines with slope 1/2 or 1/4. It means the composite model could be used into pressure interpretation of artificial fracturing wells in tight oil reservoir.

Role of fracture mechanics in modern technology

International Nuclear Information System (INIS)

Sih, G.C.

1987-01-01

The conference served as a forum not only for reviewing past concepts and technologies but it provided an opportunity for many of the designers, engineers and scientists to come forth with more advanced ideas so that fracture mechanics application can be broadened and employed more effectively to avoid unexpected failures that are annoying, costly and destructive of credibility of the engineering community in general

Flow characteristics through a single fracture of artificial fracture system

International Nuclear Information System (INIS)

Park, Byoung Yoon; Bae, Dae Seok; Kim, Chun Soo; Kim, Kyung Su; Koh, Young Kwon; Jeon, Seok Won

2001-04-01

Fracture flow in rock masses is one of the most important issues in petroleum engineering, geology, and hydrogeology. Especially, in case of the HLW disposal, groundwater flow in fractures is an important factor in the performance assessment of the repository because the radionuclides move along the flowing groundwater through fractures. Recently, the characterization of fractures and the modeling of fluid flow in fractures are studied by a great number of researchers. Among those studies, the hydraulic behavior in a single fracture is one of the basic issues for understanding of fracture flow in rockmass. In this study, a fluid flow test in the single fracture made of transparent epoxy replica was carried out to obtain the practical exponent values proposed from the Cubic law and to estimate the flow rates through a single fracture. Not only the relationship between flow rates and the geometry of fracture was studied, but also the various statistical parameters of fracture geometry were compared to the effective transmissivity data obtained from computer simulation.

Fracture toughness evaluation in the transition region of reactor pressure vessel steel

International Nuclear Information System (INIS)

Onizawa, K.; Suzuki, M.

1995-01-01

The fracture toughness (K jc and Jc) values at the cleavage fracture initiation in the transition region of a RPV steel were investigated using mainly precracked Charpy specimens. A conventional statistical approach and a fractographic study were applied to analyze the scatter of the fracture toughness values from precracked Charpy specimens. The material used was an ASTM A533B class 1 steel, which was designated as an IAEA correlation monitor material, JRQ. A lower bound transition curve of the fracture toughness for unirradiated condition was determined by the 5% confidence limit from the Weibull and fractographic analyses. The lower bound transition curve after irradiation was evaluated based on the statistics of unirradiated specimens. The results indicated that the shift of the fracture toughness transition curbe were somewhat larger than the Charpy 41J transition temperature. The parameters to determine the lower bound toughness such as the Weibull slope and the amount of ductile crack growth are discussed. The results are also compared with a model based on weakest link theory. (author). 12 refs, 12 figs, 5 tabs

A Rare Nasal Bone Fracture: Anterior Nasal Spine Fracture

Directory of Open Access Journals (Sweden)

Egemen Kucuk

2014-04-01

Full Text Available Anterior nasal spine fractures are a quite rare type of nasal bone fractures. Associated cervical spine injuries are more dangerous than the nasal bone fracture. A case of the anterior nasal spine fracture, in a 18-year-old male was presented. Fracture of the anterior nasal spine, should be considered in the differential diagnosis of the midface injuries and also accompanying cervical spine injury should not be ignored.

Surgical treatment of severe osteoporosis including new concept of advanced severe osteoporosis

Directory of Open Access Journals (Sweden)

Jin Hwan Kim

2017-12-01

Full Text Available Severe osteoporosis is classified as those with a bone mineral density (BMD T-score of −2.5 or lower, and demonstrate one or more of osteoporotic, low-trauma, fragility fractures. According to the general principle of surgical approach, patients with severe osteoporosis require not only more thorough pre- and postoperative treatment plans, but improvements in surgical fixtures and techniques such as the concept of a locking plate to prevent bone deformity and maximizing the blood flow to the fracture site by using a minimally invasive plate osteosynthesis. Arthroplasty is often performed in cases of displaced femoral neck fracture. Otherwise internal fixation for the goal of bone union is the generally accepted option for intertrochanteric, subtrochanteric, and femoral shaft fractures. Most of osteoporotic spine fracture is stable compression fracture, but vertebroplasty or kyphoplasty may be performed some selective patients. If neurological paralysis, severe spinal instability, or kyphotic deformity occurs, open decompression or fusion surgery may be considered. In order to overcome shortcomings of the World Health Organization definition of osteoporosis, we proposed a concept of ‘advanced severe osteoporosis,’ which is defined by the presence of proximal femur fragility fracture or two or more fragility fractures in addition to BMD T-score of −2.5 or less. In conclusion, we need more meticulous approach for surgical treatment of severe osteoporosis who had fragility fracture. In cases of advanced severe osteoporosis, we recommend more aggressive managements using parathyroid hormone and receptor activator of nuclear factor kappa-B ligand monoclonal antibody.

A Mobile Communications Space Link Between the Space Shuttle Orbiter and the Advanced Communications Technology Satellite

Science.gov (United States)

Fink, Patrick; Arndt, G. D.; Bondyopadhyay, P.; Shaw, Roland

1994-01-01

A communications experiment is described as a link between the Space Shuttle Orbiter (SSO) and the Advanced Communications Technology Satellite (ACTS). Breadboarding for this experiment has led to two items with potential for commercial application: a 1-Watt Ka-band amplifier and a Ka-band, circularly polarized microstrip antenna. Results of the hybrid Ka-band amplifier show gain at 30 dB and a saturated output power of 28.5 dBm. A second version comprised of MMIC amplifiers is discussed. Test results of the microstrip antenna subarray show a gain of approximately 13 dB and excellent circular polarization.

A Computational/Experimental Platform for Investigating Three-Dimensional Puzzle Solving of Comminuted Articular Fractures

Science.gov (United States)

Thomas, Thaddeus P.; Anderson, Donald D.; Willis, Andrew R.; Liu, Pengcheng; Frank, Matthew C.; Marsh, J. Lawrence; Brown, Thomas D.

2011-01-01

Reconstructing highly comminuted articular fractures poses a difficult surgical challenge, akin to solving a complicated three-dimensional (3D) puzzle. Pre-operative planning using CT is critically important, given the desirability of less invasive surgical approaches. The goal of this work is to advance 3D puzzle solving methods toward use as a pre-operative tool for reconstructing these complex fractures. Methodology for generating typical fragmentation/dispersal patterns was developed. Five identical replicas of human distal tibia anatomy, were machined from blocks of high-density polyetherurethane foam (bone fragmentation surrogate), and were fractured using an instrumented drop tower. Pre- and post-fracture geometries were obtained using laser scans and CT. A semi-automatic virtual reconstruction computer program aligned fragment native (non-fracture) surfaces to a pre-fracture template. The tibias were precisely reconstructed with alignment accuracies ranging from 0.03-0.4mm. This novel technology has potential to significantly enhance surgical techniques for reconstructing comminuted intra-articular fractures, as illustrated for a representative clinical case. PMID:20924863

Fracture Risk in Type 2 Diabetes: Current Perspectives and Gender Differences

Directory of Open Access Journals (Sweden)

Giuseppina T. Russo

2016-01-01

Full Text Available Type 2 diabetes mellitus (T2DM is associated with an increased risk of osteoporotic fractures, resulting in disabilities and increased mortality. The pathophysiological mechanisms linking diabetes to osteoporosis have not been fully explained, but alterations in bone structure and quality are well described in diabetic subjects, likely due to a combination of different factors. Insulin deficiency and dysfunction, obesity and hyperinsulinemia, altered level of oestrogen, leptin, and adiponectin as well as diabetes-related complications, especially peripheral neuropathy, orthostatic hypotension, or reduced vision due to retinopathy may all be associated with an impairment in bone metabolism and with the increased risk of fractures. Finally, medications commonly used in the treatment of T2DM may have an impact on bone metabolism and on fracture risk, particularly in postmenopausal women. When considering the impact of hypoglycaemic drugs on bone, it is important to balance their potential direct effects on bone quality with the risk of falling-related fractures due to the associated hypoglycaemic risk. In this review, experimental and clinical evidence connecting bone metabolism and fracture risk to T2DM is discussed, with particular emphasis on hypoglycaemic treatments and gender-specific implications.

Remote Sensing Applications for Antrim Shale Fracture Characterization, Michigan Basin

Science.gov (United States)

Kuuskraa, Vello

1997-01-01

Advanced Research International (ARI) sent seven staff members to the 1997 International Coalbed Methane Symposium, held in Tuscaloosa, Alabama from May 12-17. ARI gave a short course on risk reduction strategies, including remote fracture detection, for coalbed methane exploration and development that was attended by about 25 coalbed methane industry professionals; and presented a paper entitled 'Optimizing coalbed methane cavity completion operations with the application of a new discrete element model.' We met with many potential clients and discussed our fracture detection services. China has vast coalbed methane resources, but is still highly dependent on coal-and wood-burning. This workshop, sponsored by the United Nations, was intended to help China develop its less-polluting energy reserves. ARI is successfully finding new applications for its fracture detection services. Coalbed methane exploration became an important market in this quarter, with the inception of a joint industry/government collaboration between ARI, Texaco and DOE to use remote fracture detection to identify areas with good potential for coalbed methane production in the Ferron Coal Trend of central Utah. Geothermal energy exploration is another emerging market for ARI, where fracture detection is applied to identify pathways for groundwater recharge, movement, and the locations of potential geothermal reservoirs. Ari continued work on two industry/government collaborations to demonstrate fracture detection to potential clients. Also completed the technical content layout for multimedia CD-ROM that describes our remote fracture detection services.

Fracture of the styloid process associated with the mandible fracture

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K N Dubey

2013-01-01

Full Text Available Fracture of the styloid process (SP of temporal bone is an uncommon injuries. Fracture of the SP can be associated with the facial injuries including mandible fracture. However, injury to the SP may be concealed and missed diagnosis may lead to the improper or various unnecessary treatments. A rare case of SP fracture associated with the ipsilateral mandibular fracture and also the diagnostic and management considerations of the SP fracture are discussed.

Coupled processes in single fractures, double fractures and fractured porous media

International Nuclear Information System (INIS)

Tsang, C.F.

1986-12-01

The emplacement of a nuclear waste repository in a fractured porous medium provides a heat source of large dimensions over an extended period of time. It also creates a large cavity in the rock mass, changing significantly the stress field. Such major changes induce various coupled thermohydraulic, hydromechanic and hydrochemical transport processes in the environment around a nuclear waste repository. The present paper gives, first, a general overview of the coupled processes involving thermal, mechanical, hydrological and chemical effects. Then investigations of a number of specific coupled processes are described in the context of fluid flow and transport in a single fracture, two intersecting fractures and a fractured porous medium near a nuclear waste repository. The results are presented and discussed

Standard test method for plane-strain (Chevron-Notch) fracture toughness of metallic materials

CERN Document Server

American Society for Testing and Materials. Philadelphia

1997-01-01

1.1 This test method covers the determination of plane-strain (chevron-notch) fracture toughnesses, KIv or KIvM, of metallic materials. Fracture toughness by this method is relative to a slowly advancing steady state crack initiated at a chevron-shaped notch, and propagating in a chevron-shaped ligament (Fig. 1). Some metallic materials, when tested by this method, exhibit a sporadic crack growth in which the crack front remains nearly stationary until a critical load is reached. The crack then becomes unstable and suddenly advances at high speed to the next arrest point. For these materials, this test method covers the determination of the plane-strain fracture toughness, KIvj or KIvM, relative to the crack at the points of instability. Note 1—One difference between this test method and Test Method E 399 (which measures KIc) is that Test Method E 399 centers attention on the start of crack extension from a fatigue precrack. This test method makes use of either a steady state slowly propagating crack, or a...

Facial Fractures.

Science.gov (United States)

Ghosh, Rajarshi; Gopalkrishnan, Kulandaswamy

2018-06-01

The aim of this study is to retrospectively analyze the incidence of facial fractures along with age, gender predilection, etiology, commonest site, associated dental injuries, and any complications of patients operated in Craniofacial Unit of SDM College of Dental Sciences and Hospital. This retrospective study was conducted at the Department of OMFS, SDM College of Dental Sciences, Dharwad from January 2003 to December 2013. Data were recorded for the cause of injury, age and gender distribution, frequency and type of injury, localization and frequency of soft tissue injuries, dentoalveolar trauma, facial bone fractures, complications, concomitant injuries, and different treatment protocols.All the data were analyzed using statistical analysis that is chi-squared test. A total of 1146 patients reported at our unit with facial fractures during these 10 years. Males accounted for a higher frequency of facial fractures (88.8%). Mandible was the commonest bone to be fractured among all the facial bones (71.2%). Maxillary central incisors were the most common teeth to be injured (33.8%) and avulsion was the most common type of injury (44.6%). Commonest postoperative complication was plate infection (11%) leading to plate removal. Other injuries associated with facial fractures were rib fractures, head injuries, upper and lower limb fractures, etc., among these rib fractures were seen most frequently (21.6%). This study was performed to compare the different etiologic factors leading to diverse facial fracture patterns. By statistical analysis of this record the authors come to know about the relationship of facial fractures with gender, age, associated comorbidities, etc.

Patellar Sleeve Fracture With Ossification of the Patellar Tendon.

Science.gov (United States)

Damrow, Derek S; Van Valin, Scott E

2017-03-01

Patellar sleeve fractures make up greater than 50% of all patellar fractures. They are essentially only seen in the pediatric population because of the thick periosteum and the distal patellar pole apophysis in this group. These fractures can lead to complications if not treated appropriately and in a timely fashion. Complications of missed or untreated patellar sleeve fractures include patella alta, anterior knee pain, and quadriceps atrophy. These can all result in severe limitations in activity. The authors describe a case of a 16-year-old boy who sustained a patellar sleeve fracture 3 years prior to presentation. On presentation, he had patella alta, diminished strength, 5° of extensor lag, and radiographs that revealed bone formation along the patellar tendon. Despite this, he was able to maintain a high level of activity. This case report explores how the patient could have maintained a high level of activity despite having a patellar sleeve fracture. Also, because of the delayed presentation, the patella was ossified and the quadriceps was retracted, which led to a novel approach to reconstructing his distal extensor mechanism. This approach included a V-Y advancement of the quadriceps tendon and patellar tendon reconstruction using the patient's hamstring tendon (semitendinosus). This technique, combined with physical therapy postoperatively, resulted in his return to varsity high school soccer. To the best of the authors' knowledge, this technique has not been reported for this rare condition. [Orthopedics. 2017; 40(2):e357-e359.]. Copyright 2016, SLACK Incorporated.

Chance Fracture Secondary to a Healed Kyphotic Compression Osteoporotic Fracture

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Teh KK

2009-11-01

Full Text Available Chance fracture is an unstable vertebral fracture, which usually results from a high velocity injury. An elderly lady with a previously healed osteoporotic fracture of the T12 and L1 vertebra which resulted in a severe kyphotic deformity subsequently sustained a Chance fracture of the adjacent L2 vertebrae after a minor fall. The previously fracture left her with a deformity which resulted in significant sagittal imbalance therefore predisposing her to this fracture. This case highlights the importance of aggressive treatment of osteoporotic fractures in order to prevent significant sagittal imbalance from resultant (i.e. kyphotic deformity.

Fracturing across the multi-scales of diverse materials

Science.gov (United States)

Armstrong, R. W.; Antolovich, S. D.; Griffiths, J. R.; Knott, J. F.

2015-01-01

Everyone has to deal with fracturing of materials at one level or another, beginning from normal household chores and extending to the largest scale of observations reported for catastrophic events occurring on a geological level or even expanded to events in outer space. Such wide perspective is introduced in the current introduction of this theme issue. The follow-on organization of technical articles provides a flavour of the range in size scales at which fracturing occurs in a wide diversity of materials—from ‘fracking’ oil extraction and earth moving to laboratory testing of rock material and extending to the cracking of tooth enamel. Of important scientific interest are observations made and analysed at the smallest dimensions corresponding to the mechanisms by which fracture is either enhanced or hindered by permanent deformation or other processes. Such events are irrevocably linked to the atomic structure in all engineering materials, a sampling of which is presented, including results for crystalline and amorphous materials. Hooray for the broad subject description that is hoped to be appealing to the interested reader. PMID:25713460

An overview of hydraulic fracturing and other formation stimulation technologies for shale gas production

OpenAIRE

GANDOSSI Luca

2013-01-01

The technology of hydraulic fracturing for hydrocarbon well stimulation is not new, but only fairly recently has become a very common and widespread technique, especially in North America, due to technological advances that have allowed extracting natural gas from so-called unconventional reservoirs (tight sands, coal beds and shale formations). The conjunction of techniques such as directional drilling, high volume fracturing, micro-seismic monitoring, etc. with the development of multi-well...

Hip Fracture

Science.gov (United States)

... hip fractures in people of all ages. In older adults, a hip fracture is most often a result of a fall from a standing height. In people with very weak bones, a hip fracture can occur simply by standing on the leg and twisting. Risk factors The rate of hip fractures increases substantially with ...

Differential fracture healing resulting from fixation stiffness variability. A mouse model

International Nuclear Information System (INIS)

Gardner, M.J.; Putnam, S.M.; Wong, A.; Streubel, P.N.; Kotiya, A.; Silva, M.J.

2011-01-01

The mechanisms underlying the interaction between the local mechanical environment and fracture healing are not known. We developed a mouse femoral fracture model with implants of different stiffness, and hypothesized that differential fracture healing would result. Femoral shaft fractures were created in 70 mice, and were treated with an intramedullary nail made of either tungsten (Young's modulus=410 GPa) or aluminium (Young's modulus=70 GPa). Mice were then sacrificed at 2 or 5 weeks. Fracture calluses were analyzed using standard microCT, histological, and biomechanical methods. At 2 weeks, callus volume was significantly greater in the aluminium group than in the tungsten group (61.2 vs. 40.5 mm 3 , p=0.016), yet bone volume within the calluses was no different between the groups (13.2 vs. 12.3 mm 3 ). Calluses from the tungsten group were stiffer on mechanical testing (18.7 vs. 9.7 N/mm, p=0.01). The percent cartilage in the callus was 31.6% in the aluminium group and 22.9% in the tungsten group (p=0.40). At 5 weeks, there were no differences between any of the healed femora. In this study, fracture implants of different stiffness led to different fracture healing in this mouse fracture model. Fractures treated with a stiffer implant had more advanced healing at 2 weeks, but still healed by callus formation. Although this concept has been well documented previously, this particular model could be a valuable research tool to study the healing consequences of altered fixation stiffness, which may provide insight into the pathogenesis and ideal treatment of fractures and non-unions. (author)

Ankle fractures have features of an osteoporotic fracture.

Science.gov (United States)

Lee, K M; Chung, C Y; Kwon, S S; Won, S H; Lee, S Y; Chung, M K; Park, M S

2013-11-01

We report the bone attenuation of ankle joint measured on computed tomography (CT) and the cause of injury in patients with ankle fractures. The results showed age- and gender-dependent low bone attenuation and low-energy trauma in elderly females, which suggest the osteoporotic features of ankle fractures. This study was performed to investigate the osteoporotic features of ankle fracture in terms of bone attenuation and cause of injury. One hundred ninety-four patients (mean age 51.0 years, standard deviation 15.8 years; 98 males and 96 females) with ankle fracture were included. All patients underwent CT examination, and causes of injury (high/low-energy trauma) were recorded. Mean bone attenuations of the talus, medial malleolus, lateral malleolus, and distal tibial metaphysis were measured on CT images. Patients were divided into younger age (fractures than the younger age group. With increasing age, bone attenuations tended to decrease and the difference of bone attenuation between the genders tended to increase in the talus, medial malleolus, lateral malleolus, and distal tibial metaphysis. Ankle fracture had features of osteoporotic fracture that is characterized by age- and gender-dependent low bone attenuation. Ankle fracture should not be excluded from the clinical and research interest as well as from the benefit of osteoporosis management.

A fully coupled finite element framework for thermal fracturing simulation in subsurface cold CO2 injection

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Shunde Yin

2018-03-01

Simulation of thermal fracturing during cold CO2 injection involves the coupled processes of heat transfer, mass transport, rock deforming as well as fracture propagation. To model such a complex coupled system, a fully coupled finite element framework for thermal fracturing simulation is presented. This framework is based on the theory of non-isothermal multiphase flow in fracturing porous media. It takes advantage of recent advances in stabilized finite element and extended finite element methods. The stabilized finite element method overcomes the numerical instability encountered when the traditional finite element method is used to solve the convection dominated heat transfer equation, while the extended finite element method overcomes the limitation with traditional finite element method that a model has to be remeshed when a fracture is initiated or propagating and fracturing paths have to be aligned with element boundaries.

Naturally fractured tight gas: Gas reservoir detection optimization. Quarterly report, January 1--March 31, 1997

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-12-31

Economically viable natural gas production from the low permeability Mesaverde Formation in the Piceance Basin, Colorado requires the presence of an intense set of open natural fractures. Establishing the regional presence and specific location of such natural fractures is the highest priority exploration goal in the Piceance and other western US tight, gas-centered basins. Recently, Advanced Resources International, Inc. (ARI) completed a field program at Rulison Field, Piceance Basin, to test and demonstrate the use of advanced seismic methods to locate and characterize natural fractures. This project began with a comprehensive review of the tectonic history, state of stress and fracture genesis of the basin. A high resolution aeromagnetic survey, interpreted satellite and SLAR imagery, and 400 line miles of 2-D seismic provided the foundation for the structural interpretation. The central feature of the program was the 4.5 square mile multi-azimuth 3-D seismic P-wave survey to locate natural fracture anomalies. The interpreted seismic attributes are being tested against a control data set of 27 wells. Additional wells are currently being drilled at Rulison, on close 40 acre spacings, to establish the productivity from the seismically observed fracture anomalies. A similar regional prospecting and seismic program is being considered for another part of the basin. The preliminary results indicate that detailed mapping of fault geometries and use of azimuthally defined seismic attributes exhibit close correlation with high productivity gas wells. The performance of the ten new wells, being drilled in the seismic grid in late 1996 and early 1997, will help demonstrate the reliability of this natural fracture detection and mapping technology.

Advances in osteoporosis imaging

International Nuclear Information System (INIS)

Bauer, Jan S.; Link, Thomas M.

2009-01-01

In the assessment of osteoporosis, the measurement of bone mineral density (BMD a ) obtained from dual energy X-ray absorptiometry (DXA; g/cm 2 ) is the most widely used parameter. However, bone strength and fracture risk are also influenced by parameters of bone quality such as micro-architecture and tissue properties. This article reviews the radiological techniques currently available for imaging and quantifying bone structure, as well as advanced techniques to image bone quality. With the recent developments in magnetic resonance (MR) techniques, including the availability of clinical 3 T scanners, and advances in computed tomography (CT) technology (e.g. clinical Micro-CT), in-vivo imaging of the trabecular bone architecture is becoming more feasible. Several in-vitro studies have demonstrated that bone architecture, measured by MR or CT, was a BMD-independent determinant of bone strength. In-vivo studies showed that patients with, and without, osteoporotic fractures could better be separated with parameters of bone architecture than with BMD. Parameters of trabecular architecture were more sensitive to treatment effects than BMD. Besides the 3D tomographic techniques, projection radiography has been used in the peripheral skeleton as an additional tool to better predict fracture risk than BMD alone. The quantification of the trabecular architecture included parameters of scale, shape, anisotropy and connectivity. Finite element analyses required highest resolution, but best predicted the biomechanical properties of the bone. MR diffusion and perfusion imaging and MR spectroscopy may provide measures of bone quality beyond trabecular micro-architecture.

A Rare Entity: Bilateral First Rib Fractures Accompanying Bilateral Scapular Fractures

OpenAIRE

Gulbahar, Gultekin; Kaplan, Tevfik; Turker, Hasan Bozkurt; Gundogdu, Ahmet Gokhan; Han, Serdar

2015-01-01

First rib fractures are scarce due to their well-protected anatomic locations. Bilateral first rib fractures accompanying bilateral scapular fractures are very rare, although they may be together with scapular and clavicular fractures. According to our knowledge, no case of bilateral first rib fractures accompanying bilateral scapular fractures has been reported, so we herein discussed the diagnosis, treatment, and complications of bone fractures due to thoracic trauma in bias of this rare en...

A Rare Entity: Bilateral First Rib Fractures Accompanying Bilateral Scapular Fractures.

Science.gov (United States)

Gulbahar, Gultekin; Kaplan, Tevfik; Turker, Hasan Bozkurt; Gundogdu, Ahmet Gokhan; Han, Serdar

2015-01-01

First rib fractures are scarce due to their well-protected anatomic locations. Bilateral first rib fractures accompanying bilateral scapular fractures are very rare, although they may be together with scapular and clavicular fractures. According to our knowledge, no case of bilateral first rib fractures accompanying bilateral scapular fractures has been reported, so we herein discussed the diagnosis, treatment, and complications of bone fractures due to thoracic trauma in bias of this rare entity.

Differing approaches to falls and fracture prevention between Australia and Colombia

Science.gov (United States)

Gomez, Fernando; Curcio, Carmen Lucia; Suriyaarachchi, Pushpa; Demontiero, Oddom; Duque, Gustavo

2013-01-01

Falls and fractures are major causes of morbidity and mortality in older people. More importantly, previous falls and/or fractures are the most important predictors of further events. Therefore, secondary prevention programs for falls and fractures are highly needed. However, the question is whether a secondary prevention model should focus on falls prevention alone or should be implemented in combination with fracture prevention. By comparing a falls prevention clinic in Manizales (Colombia) versus a falls and fracture prevention clinic in Sydney (Australia), the objective was to identify similarities and differences between these two programs and to propose an integrated model of care for secondary prevention of fall and fractures. A comparative study of services was performed using an internationally agreed taxonomy. Service provision was compared against benchmarks set by the National Institute for Health and Clinical Excellence (NICE) and previous reports in the literature. Comparison included organization, administration, client characteristics, and interventions. Several similarities and a number of differences that could be easily unified into a single model are reported here. Similarities included population, a multidisciplinary team, and a multifactorial assessment and intervention. Differences were eligibility criteria, a bone health assessment component, and the therapeutic interventions most commonly used at each site. In Australia, bone health assessment is reinforced whereas in Colombia dizziness assessment and management is pivotal. The authors propose that falls clinic services should be operationally linked to osteoporosis services such as a “falls and fracture prevention clinic,” which would facilitate a comprehensive intervention to prevent falls and fractures in older persons. PMID:23378748

Advanced Asymptomatic Carotid Disease and Cognitive Impairment: An Understated Link?

Directory of Open Access Journals (Sweden)

Irena Martinić-Popović

2012-01-01

Full Text Available Advanced carotid disease is known to be associated with symptomatic cerebrovascular diseases, such as stroke or transient ischemic attack (TIA, as well as with poststroke cognitive impairment. However, cognitive decline often occurs in patients with advanced carotid stenosis without clinically evident stroke or TIA, so it is also suspected to be an independent risk factor for dementia. Neurosonological methods enable simple and noninvasive assessment of carotid stenosis in patients at risk of advanced atherosclerosis. Cognitive status in patients diagnosed with advanced carotid stenosis is routinely not taken into consideration, although if cognitive impairment is present, such patients should probably be called symptomatic. In this paper, we discuss results of some most important studies that investigated cognitive status of patients with asymptomatic advanced carotid disease and possible mechanisms involved in the causal relationship between asymptomatic advanced carotid disease and cognitive decline.

Results of fracture mechanics tests on PNC SUS 304 plate

International Nuclear Information System (INIS)

Mills, W.J.; James, L.A.; Blackburn, L.D.

1985-08-01

PNC provided SUS 304 plate to be irradiated in FFTF at about 400 0 C to a target fluence of 5 x 10 21 n/cm 2 (E > 0.1 MeV). The actual irradiation included two basically different exposure levels to assure that information would be available for the exposure of interest. After irradiation, tensile properties, fatigue-crack growth rates and J-integral fracture toughness response were determined. These same properties were also measured for the unirradiated material so radiation damage effects could be characterized. This report presents the results of this program. It is expected that these results would be applicable for detailed fracture analysis of reactor components. Recent advances in elastic-plastic fracture mechanics enable reasonably accurate predictions of failure conditions for flawed stainless steel components. Extensive research has focused on the development of J-integral-based engineering approach for assessing the load carrying capacity of low-strength, high-toughness structural materials. Furthermore, Kanninen, et al., have demonstrated that J-integral concepts can accurately predict the fracture response for full-scale cracked structures manufactured from Type 304 stainless steel

Relationships between fractures

Science.gov (United States)

Peacock, D. C. P.; Sanderson, D. J.; Rotevatn, A.

2018-01-01

Fracture systems comprise many fractures that may be grouped into sets based on their orientation, type and relative age. The fractures are often arranged in a network that involves fracture branches that interact with one another. Interacting fractures are termed geometrically coupled when they share an intersection line and/or kinematically coupled when the displacements, stresses and strains of one fracture influences those of the other. Fracture interactions are characterised in terms of the following. 1) Fracture type: for example, whether they have opening (e.g., joints, veins, dykes), closing (stylolites, compaction bands), shearing (e.g., faults, deformation bands) or mixed-mode displacements. 2) Geometry (e.g., relative orientations) and topology (the arrangement of the fractures, including their connectivity). 3) Chronology: the relative ages of the fractures. 4) Kinematics: the displacement distributions of the interacting fractures. It is also suggested that interaction can be characterised in terms of mechanics, e.g., the effects of the interaction on the stress field. It is insufficient to describe only the components of a fracture network, with fuller understanding coming from determining the interactions between the different components of the network.

A Rare Entity: Bilateral First Rib Fractures Accompanying Bilateral Scapular Fractures

Directory of Open Access Journals (Sweden)

Gultekin Gulbahar

2015-01-01

Full Text Available First rib fractures are scarce due to their well-protected anatomic locations. Bilateral first rib fractures accompanying bilateral scapular fractures are very rare, although they may be together with scapular and clavicular fractures. According to our knowledge, no case of bilateral first rib fractures accompanying bilateral scapular fractures has been reported, so we herein discussed the diagnosis, treatment, and complications of bone fractures due to thoracic trauma in bias of this rare entity.

Proximal femoral fractures.

Science.gov (United States)

Webb, Lawrence X

2002-01-01

Fractures of the proximal femur include fractures of the head, neck, intertrochanteric, and subtrochanteric regions. Head fractures commonly accompany dislocations. Neck fractures and intertrochanteric fractures occur with greatest frequency in elderly patients with a low bone mineral density and are produced by low-energy mechanisms. Subtrochanteric fractures occur in a predominantly strong cortical osseous region which is exposed to large compressive stresses. Implants used to address these fractures must be able to accommodate significant loads while the fractures consolidate. Complications secondary to these injuries produce significant morbidity and include infection, nonunion, malunion, decubitus ulcers, fat emboli, deep venous thrombosis, pulmonary embolus, pneumonia, myocardial infarction, stroke, and death.

Fracture mechanisms and fracture control in composite structures

Science.gov (United States)

Kim, Wone-Chul

Four basic failure modes--delamination, delamination buckling of composite sandwich panels, first-ply failure in cross-ply laminates, and compression failure--are analyzed using linear elastic fracture mechanics (LEFM) and the J-integral method. Structural failures, including those at the micromechanical level, are investigated with the aid of the models developed, and the critical strains for crack propagation for each mode are obtained. In the structural fracture analyses area, the fracture control schemes for delamination in a composite rib stiffener and delamination buckling in composite sandwich panels subjected to in-plane compression are determined. The critical fracture strains were predicted with the aid of LEFM for delamination and the J-integral method for delamination buckling. The use of toughened matrix systems has been recommended for improved damage tolerant design for delamination crack propagation. An experimental study was conducted to determine the onset of delamination buckling in composite sandwich panel containing flaws. The critical fracture loads computed using the proposed theoretical model and a numerical computational scheme closely followed the experimental measurements made on sandwich panel specimens of graphite/epoxy faceskins and aluminum honeycomb core with varying faceskin thicknesses and core sizes. Micromechanical models of fracture in composites are explored to predict transverse cracking of cross-ply laminates and compression fracture of unidirectional composites. A modified shear lag model which takes into account the important role of interlaminar shear zones between the 0 degree and 90 degree piles in cross-ply laminate is proposed and criteria for transverse cracking have been developed. For compressive failure of unidirectional composites, pre-existing defects play an important role. Using anisotropic elasticity, the stress state around a defect under a remotely applied compressive load is obtained. The experimentally

The moderately fractured rock experiment: Background and overview

International Nuclear Information System (INIS)

Jensen, M.R.

2001-01-01

The Moderately Fractured Rock (MFR) experiment is conducted at Atomic Energy of Canada Limited's Underground Research Laboratory (URL) as part of Ontario Power Generation's Deep Geologic Repository Technology Program. The MFR experiment was initiated in the mid-1990s with the purpose of advancing the understanding of mass transport in MFR (fractures 1-5/m, k ≅ 10 -15 m 2 ) in which groundwater flow and solute migration occurs through a network of interconnected fractures. The experimental program has involved a series of multi-well forced gradient tracer tests at scales of 10-50 m within a ≅ 100,000 m 3 volume of MFR accessed from the 240 m level of the URL. The tracer tests conducted with non-reactive, reactive and colloidal tracers have served to explore the applicability of continuum models for prediction of groundwater flow and mass transport. Recently, a Modeling Task Force was created to re-examine tracer test experimental methodologies, MFR flow and transport conceptual models and provide a broader forum in which to apply alternative dual-permeability, discrete fracture and hybrid mathematical codes for flow system analysis. This paper provides a description of the MFR experiment, preliminary research findings and plans for the future

Evaluation of essential work of fracture in a dual phase high strength steel sheet

International Nuclear Information System (INIS)

Gutierrez, D.; Perez, L. I.; Lara, A.; Casellas, D.; Prado, J. M.

2013-01-01

Fracture toughness of advanced high strength steels (AHSS), can be used to optimize crash behavior of structural components. However it cannot be readily measured in metal sheet because of the sheet thickness. In this work, the Essential Work of Fracture (EWF) methodology is proposed to evaluate the fracture toughness of metal sheets. It has been successfully applied in polymers films and some metal sheets. However, their information about the applicability of this methodology to AHSS is relatively scarce. In the present work the fracture toughness of a Dual Phase (strength of 800 MPa) and drawing steel sheets has been measured by means of the EWF. The results show that the test requirements are met and also show the clear influence of notch radii on the measured values, specially for the AHSS grade. Thus, the EWF is postulated as a methodology to evaluate the fracture toughness in AHSS sheets. (Author) 18 refs.

The effect of crack instability/stability on fracture toughness of brittle materials

International Nuclear Information System (INIS)

Baratta, F.I.

1997-01-01

This paper summarizes three recent experimental works coauthored by the present author regarding the effect of crack instability/stability on fracture toughness, and also includes the necessary formulae for predicting stability. Two recent works have shown that unstable crack extension resulted in apparent increases in fracture toughness compared to that determined during stable crack growth. In the first investigation a quasi-brittle polymer, polymethylmethacrylate, was examined. In the second, a more brittle metallic material, tungsten, was tested. In both cases the transition from unstable to stable behavior was predicted based on stability analyses. The third investigation was conducted on a truly brittle ceramic material, hot pressed silicon nitride. These three papers showed that fracture toughness test results conducted on brittle materials vary according to whether the material fractures in an unstable or stable manner. Suggestions for achieving this important yet difficult phenomenon of stable crack growth, which is necessary when determining the fracture toughness variation occurring during unstable/stable crack advance, are presented, as well as recommendations for further research

Investigation of translaminar fracture in fibrereinforced composite laminates---applicability of linear elastic fracture mechanics and cohesive-zone model

Science.gov (United States)

Hou, Fang

With the extensive application of fiber-reinforced composite laminates in industry, research on the fracture mechanisms of this type of materials have drawn more and more attentions. A variety of fracture theories and models have been developed. Among them, the linear elastic fracture mechanics (LEFM) and cohesive-zone model (CZM) are two widely-accepted fracture models, which have already shown applicability in the fracture analysis of fiber-reinforced composite laminates. However, there remain challenges which prevent further applications of the two fracture models, such as the experimental measurement of fracture resistance. This dissertation primarily focused on the study of the applicability of LEFM and CZM for the fracture analysis of translaminar fracture in fibre-reinforced composite laminates. The research for each fracture model consisted of two sections: the analytical characterization of crack-tip fields and the experimental measurement of fracture resistance parameters. In the study of LEFM, an experimental investigation based on full-field crack-tip displacement measurements was carried out as a way to characterize the subcritical and steady-state crack advances in translaminar fracture of fiber-reinforced composite laminates. Here, the fiber-reinforced composite laminates were approximated as anisotropic solids. The experimental investigation relied on the LEFM theory with a modification with respect to the material anisotropy. Firstly, the full-field crack-tip displacement fields were measured by Digital Image Correlation (DIC). Then two methods, separately based on the stress intensity approach and the energy approach, were developed to measure the crack-tip field parameters from crack-tip displacement fields. The studied crack-tip field parameters included the stress intensity factor, energy release rate and effective crack length. Moreover, the crack-growth resistance curves (R-curves) were constructed with the measured crack-tip field parameters

Fracture morphology of carbon fiber reinforced plastic composite laminates

Directory of Open Access Journals (Sweden)

Vinod Srinivasa

2010-09-01

Full Text Available Carbon fiber reinforced plastic (CFRP composites have been extensively used in fabrication of primary structures for aerospace, automobile and other engineering applications. With continuous and widespread use of these composites in several advanced technology, the frequency of failures is likely to increase. Therefore, to establish the reasons for failures, the fracture modes should be understood thoroughly and unambiguously. In this paper, CFRP composite have been tested in tension, compression and flexural loadings; and microscopic study with the aid of Scanning Electron Microscope (SEM has been performed on failed (fractured composite surfaces to identify the principle features of failure. Efforts have been made in correlating the fracture surface characteristics to the failure mode. The micro-mechanics analysis of failure serves as a useful guide in selecting constituent materials and designing composites from the failure behavior point of view. Also, the local failure initiation results obtained here has been reliably extended to global failure prediction.

Monitoring hydraulic fractures: state estimation using an extended Kalman filter

International Nuclear Information System (INIS)

Rochinha, Fernando Alves; Peirce, Anthony

2010-01-01

There is considerable interest in using remote elastostatic deformations to identify the evolving geometry of underground fractures that are forced to propagate by the injection of high pressure viscous fluids. These so-called hydraulic fractures are used to increase the permeability in oil and gas reservoirs as well as to pre-fracture ore-bodies for enhanced mineral extraction. The undesirable intrusion of these hydraulic fractures into environmentally sensitive areas or into regions in mines which might pose safety hazards has stimulated the search for techniques to enable the evolving hydraulic fracture geometries to be monitored. Previous approaches to this problem have involved the inversion of the elastostatic data at isolated time steps in the time series provided by tiltmeter measurements of the displacement gradient field at selected points in the elastic medium. At each time step, parameters in simple static models of the fracture (e.g. a single displacement discontinuity) are identified. The approach adopted in this paper is not to regard the sequence of sampled elastostatic data as independent, but rather to treat the data as linked by the coupled elastic-lubrication equations that govern the propagation of the evolving hydraulic fracture. We combine the Extended Kalman Filter (EKF) with features of a recently developed implicit numerical scheme to solve the coupled free boundary problem in order to form a novel algorithm to identify the evolving fracture geometry. Numerical experiments demonstrate that, despite excluding significant physical processes in the forward numerical model, the EKF-numerical algorithm is able to compensate for the un-modeled dynamics by using the information fed back from tiltmeter data. Indeed the proposed algorithm is able to provide reasonably faithful estimates of the fracture geometry, which are shown to converge to the actual hydraulic fracture geometry as the number of tiltmeters is increased. Since the location of

Dating fractures and fracture movement in the Lac du Bonnet Batholith

International Nuclear Information System (INIS)

Gascoyne, M.; Brown, A.; Ejeckam, R.B.; Everitt, R.A.

1997-04-01

This report examines and summarizes all work that has been done from 1980 to the present in determining the age of rock crystallization, fracture initiation, fracture reactivation and rates of fracture movement in the Lac du Bonnet Batholith to provide information for Atomic Energy of Canada Limited's (AECL) Canadian Nuclear Fuel Waste Management Program. Geological and petrographical indicators of relative age (e.g. cross-cutting relationships, sequences of fracture infilling minerals, P-T characteristics of primary and secondary minerals) are calibrated with radiometric age determinations on minerals and whole rock samples, using 87 Rb- 87 Sr, 40 K- 39 Ar, 40 Ar- 39 Ar and fission track methods. Most fractures and fracture zones inclined at low angles are found to be ancient features, first formed in the Early Proterozoic under conditions of deuteric alteration. Following some movement on fractures in the Late Proterozoic and Early Paleozoic, reactivation of fractures during the Pleistocene is established from uranium-series dating methods and use of stable isotopic contents of fracture infilling minerals (mainly calcite). Some indication of movement on fracture zones during the Pleistocene is given by electron spin resonance dating techniques on fault gouge. The slow rate of propagation of fractures is indicated by mineral infillings, their P-T characteristics and U-series calcite ages in a fracture in sparsely fractured rock, accessible from AECL's Underground Research Laboratory. These results collectively indicate that deep fractures observed in the batholith are ancient features and the fracturing and jointing in the upper 200 m is relatively recent (< 1 Ma) and largely a result of stress release. (author)

Modeling the Fracture of Ice Sheets on Parallel Computers

Energy Technology Data Exchange (ETDEWEB)

Waisman, Haim [Columbia Univ., New York, NY (United States); Tuminaro, Ray [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2013-10-10

The objective of this project was to investigate the complex fracture of ice and understand its role within larger ice sheet simulations and global climate change. This objective was achieved by developing novel physics based models for ice, novel numerical tools to enable the modeling of the physics and by collaboration with the ice community experts. At the present time, ice fracture is not explicitly considered within ice sheet models due in part to large computational costs associated with the accurate modeling of this complex phenomena. However, fracture not only plays an extremely important role in regional behavior but also influences ice dynamics over much larger zones in ways that are currently not well understood. To this end, our research findings through this project offers significant advancement to the field and closes a large gap of knowledge in understanding and modeling the fracture of ice sheets in the polar regions. Thus, we believe that our objective has been achieved and our research accomplishments are significant. This is corroborated through a set of published papers, posters and presentations at technical conferences in the field. In particular significant progress has been made in the mechanics of ice, fracture of ice sheets and ice shelves in polar regions and sophisticated numerical methods that enable the solution of the physics in an efficient way.

VSP in crystalline rocks - from downhole velocity profiling to 3-D fracture mapping

International Nuclear Information System (INIS)

Cosma, C.; Heikkinen, P.; Keskinen, J.; Enescu, N.

1998-01-01

VSP surveys have been carried out at several potential nuclear waste disposal sites in Finland since the mid 80s. To date, more than 200 three-component profiles have been measured. The main purpose of the surveys was to detect fracture zones in the crystalline bedrock and to determine their position. Most seismic events could be linked to zones of increased fracturing observed in the borehole logs. The more pronounced seismic reflectors could be correlated with hydrogeologically significant zones, which have been the main targets in the investigations. Processing and interpretation methods have been developed specifically for VSP surveys in crystalline rocks: Weak reflections from thin fracture zones are enhanced by multi-channel filtering techniques based on the Radon transform. The position and orientation of the fracture zones are determined by polarisation analysis and by combining data from several shot points. The compilation of the results from several boreholes gives a comprehensive image of the fracture zones at the scale of the whole site. The discussion of the methodology is based on examples from the Olkiluoto site, in SW Finland

Estimated drinking water fluoride exposure and risk of hip fracture: a cohort study.

Science.gov (United States)

Näsman, P; Ekstrand, J; Granath, F; Ekbom, A; Fored, C M

2013-11-01

The cariostatic benefit from water fluoridation is indisputable, but the knowledge of possible adverse effects on bone and fracture risk due to fluoride exposure is ambiguous. The association between long-term (chronic) drinking water fluoride exposure and hip fracture (ICD-7-9: '820' and ICD-10: 'S72.0-S72.2') was assessed in Sweden using nationwide registers. All individuals born in Sweden between January 1, 1900 and December 31, 1919, alive and living in their municipality of birth at the time of start of follow-up, were eligible for this study. Information on the study population (n = 473,277) was linked among the Swedish National In-Patient Register (IPR), the Swedish Cause of Death Register, and the Register of Population and Population Changes. Estimated individual drinking water fluoride exposure was stratified into 4 categories: very low, hip fracture. The risk estimates did not change in analyses restricted to only low-trauma osteoporotic hip fractures. Chronic fluoride exposure from drinking water does not seem to have any important effects on the risk of hip fracture, in the investigated exposure range.

Deformation aspects of time dependent fracture

International Nuclear Information System (INIS)

Li, C.Y.; Turner, A.P.L.; Diercks, D.R.; Laird, C.; Langdon, T.G.; Nix, W.D.; Swindeman, R.; Wolfer, W.G.; Woodford, D.A.

1979-01-01

For all metallic materials, particularly at elevated temperatures, deformation plays an important role in fracture. On the macro-continuum level, the inelastic deformation behavior of the material determines how stress is distributed in the body and thus determines the driving force for fracture. At the micro-continuum level, inelastic deformation alters the elastic stress singularity at the crack tip and so determines the local environment in which crack advance takes place. At the microscopic and mechanistic level, there are many possibilities for the mechanisms of deformation to be related to those for crack initiation and growth. At elevated temperatures, inelastic deformation in metallic systems is time dependent so that the distribution of stress in a body will vary with time, affecting conditions for crack initiation and propagation. Creep deformation can reduce the tendency for fracture by relaxing the stresses at geometric stress concentrations. It can also, under suitable constraints, cause a concentration of stresses at specific loading points as a result of relaxation elsewhere in the body. A combination of deformation and unequal heating, as in welding, can generate large residual stress which cannot be predicted from the external loads on the body. Acceleration of deformation by raising the temperature can be an effective way to relieve such residual stresses

PEPSI-feed: linking PEPSI to the Vatican Advanced Technology Telescope using a 450m long fibre

Science.gov (United States)

Sablowski, D. P.; Weber, M.; Woche, M.; Ilyin, I.; Järvinen, A.; Strassmeier, K. G.; Gabor, P.

2016-07-01

Limited observing time at large telescopes equipped with the most powerful spectrographs makes it almost impossible to gain long and well-sampled time-series observations. Ditto, high-time-resolution observations of bright targets with high signal-to-noise are rare. By pulling an optical fibre of 450m length from the Vatican Advanced Technology Telescope (VATT) to the Large Binocular Telescope (LBT) to connect the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) to the VATT, allows for ultra-high resolution time-series measurements of bright targets. This article presents the fibre-link in detail from the technical point-of-view, demonstrates its performance from first observations, and sketches current applications.

Characterization and interpretation of a fractured rocky massif from borehole data. Boreholes of geothermal project at Soultz-sous-Forets and other examples of unidirectional sampling; Caracterisation et interpretation d`un volume rocheux fracture a partir de donnees de forages. Les forages geothermiques de Soultz-sous-Forets et autres exemples d`echantillonnages unidirectionnels

Energy Technology Data Exchange (ETDEWEB)

Dezayes, CH

1995-12-18

In this thesis, we study fractures from borehole data on two sites: in one, located at Soultz-sous-Forets (Alsace) in the Rhine graben, boreholes reach a delta Jurassic series forming a petroleum reservoir. At Soultz, fractures have been studied on cores and borehole images. Striated faults present on cores permit to determine the tectonic history of the granite, completed by field study in Vosges Massif. This history corresponds to the Rhine graben history knowing by different authors. The analysis of vertical induced fractures observed on borehole images indicates a present-day NW-SE to NNW-SSE compression. These variations of stress direction are confirmed by others in situ measurements, as hydraulic injection, micro-seismicity, etc... On cores and borehole images, numerous fractures have been observed. Most of them are linked to the E-W distension, which permits the Rhine graben opening at Oligocene. At greatest scale, in quartz minerals, the micro-fractures are constitute by fluid inclusion trails. Several sets are related to the E-W distension, but others sets are linked to compressive stages. These sets are not observed on cores. This is a under-sampling of some fractures by the boreholes, but theses fractures exit into to rock massif. On borehole images, fracture density is weakest than the cores, however the set organisation is the same. At Ravenscar, the distribution of fracture spacing along different unidirectional sampling shows a exponential negative law. However, the fracture density varies with sampling. (author) 199 refs.

Acetabular fractures following rugby tackles: a case series

Directory of Open Access Journals (Sweden)

Morris Seamus

2011-10-01

Full Text Available Abstract Introduction Rugby is the third most popular team contact sport in the world and is increasing in popularity. In 1995, rugby in Europe turned professional, and with this has come an increased rate of injury. Case presentation In a six-month period from July to December, two open reduction and internal fixations of acetabular fractures were performed in young Caucasian men (16 and 24 years old who sustained their injuries after rugby tackles. Both of these cases are described as well as the biomechanical factors contributing to the fracture and the recovery. Acetabular fractures of the hip during sport are rare occurrences. Conclusion Our recent experience of two cases over a six-month period creates concern that these high-energy injuries may become more frequent as rugby continues to adopt advanced training regimens. Protective equipment is unlikely to reduce the forces imparted across the hip joint; however, limiting 'the tackle' to only two players may well reduce the likelihood of this life-altering injury.

Numerical Analysis of AHSS Fracture in a Stretch-bending Test

Science.gov (United States)

Luo, Meng; Chen, Xiaoming; Shi, Ming F.; Shih, Hua-Chu

2010-06-01

Advanced High Strength Steels (AHSS) are increasingly used in the automotive industry due to their superior strength and substantial weight reduction advantage. However, their limited ductility gives rise to numerous manufacturing issues. One of them is the so-called `shear fracture' often observed on tight radii during stamping processes. Since traditional approaches, such as the Forming Limit Diagram (FLD), are unable to predict this type of fracture, efforts have been made to develop failure criteria that can predict shear fractures. In this paper, a recently developed Modified Mohr-Coulomb (MMC) ductile fracture criterion[1] is adopted to analyze the failure behavior of a Dual Phase (DP) steel sheet during stretch bending operations. The plasticity and ductile fracture of the present sheet are fully characterized by the Hill'48 orthotropic model and the MMC fracture model respectively. Finite Element models with three different element types (3D, shell and plane strain) were built for a Stretch Forming Simulator (SFS) test and numerical simulations with four different R/t ratios (die radius normalized by sheet thickness) were performed. It has been shown that the 3D and shell element models can accurately predict the failure location/mode, the upper die load-displacement responses as well as the wall stress and wrap angle at the onset of fracture for all R/t ratios. Furthermore, a series of parametric studies were conducted on the 3D element model, and the effects of tension level (clamping distance) and tooling friction on the failure modes/locations were investigated.

Hydraulic fracturing in shales: the spark that created an oil and gas boom

Science.gov (United States)

Olson, J. E.

2017-12-01

In the oil and gas business, one of the valued properties of a shale was its lack of flow capacity (its sealing integrity) and its propensity to provide mechanical barriers to hydraulic fracture height growth when exploiting oil and gas bearing sandstones. The other important property was the high organic content that made shale a potential source rock for oil and gas, commodities which migrated elsewhere to be produced. Technological advancements in horizontal drilling and hydraulic fracturing have turned this perspective on its head, making shale (or other ultra-low permeability rocks that are described with this catch-all term) the most prized reservoir rock in US onshore operations. Field and laboratory results have changed our view of how hydraulic fracturing works, suggesting heterogeneities like bedding planes and natural fractures can cause significant complexity in hydraulic fracture growth, resulting in induced networks of fractures whose details are controlled by factors including in situ stress contrasts, ductility contrasts in the stratigraphy, the orientation and strength of pre-existing natural fractures, injection fluid viscosity, perforation cluster spacing and effective mechanical layer thickness. The stress shadowing and stress relief concepts that structural geologists have long used to explain joint spacing and orthogonal fracture pattern development in stratified sequences are key to understanding optimal injection point spacing and promotion of more uniform length development in induced hydraulic fractures. Also, fracture interaction criterion to interpret abutting vs crossing natural fracture relationships in natural fracture systems are key to modeling hydraulic fracture propagation within natural fractured reservoirs such as shale. Scaled physical experiments provide constraints on models where the physics is uncertain. Numerous interesting technical questions remain to be answered, and the field is particularly appealing in that better

Physical fracture properties (fracture surfaces as information sources; crackgrowth and fracture mechanisms; exemples of cracks)

International Nuclear Information System (INIS)

Meny, Lucienne.

1979-06-01

Fracture surfaces are considered as a useful source of informations: an introduction to fractography is presented; the fracture surface may be observed through X ray microanalysis, and other physical methods such as Auger electron spectroscopy or secundary ion emission. The mechanisms of macroscopic and microscopic crackgrowth and fracture are described, in the case of unstable fracture (cleavage, ductile with shear, intergranular brittleness) and of progressive crack propagation (creep, fatigue). Exemples of cracks are presented in the last chapter [fr

Advanced TCA Backplane Tester

CERN Document Server

Oltean, Alexandra Dana

2004-01-01

At the beginning of 2003, the PICMG group adopted the AdvancedTCA (Advanced Telecom Computing Architecture) standard. The 10Gb/s backplane of the AdvancedTCA chassis is well specified in the standard but it remains however a high end product, which can be itself subject to printed circuit board manufacturing control problems that could greatly affect its quality control. In order to study the practical aspects of high speed Ethernet switching at 10Gb/s and to validate the signal integrity of the AdvancedTCA backplane, we developed a Backplane Tester. The tester system is able of running monitored PRBS traffic at 3.125Gb/s over every link on the AdvancedTCA backplane simultaneously and to monitor any possible connectivity failure immediately in terms of link and slot position inside the chassis. The present report presents the architectural hardware design, the control structure and software aspects of the AdvancedTCA Backplane Tester design.

Large-scale simulation of ductile fracture process of microstructured materials

International Nuclear Information System (INIS)

Tian Rong; Wang Chaowei

2011-01-01

The promise of computational science in the extreme-scale computing era is to reduce and decompose macroscopic complexities into microscopic simplicities with the expense of high spatial and temporal resolution of computing. In materials science and engineering, the direct combination of 3D microstructure data sets and 3D large-scale simulations provides unique opportunity for the development of a comprehensive understanding of nano/microstructure-property relationships in order to systematically design materials with specific desired properties. In the paper, we present a framework simulating the ductile fracture process zone in microstructural detail. The experimentally reconstructed microstructural data set is directly embedded into a FE mesh model to improve the simulation fidelity of microstructure effects on fracture toughness. To the best of our knowledge, it is for the first time that the linking of fracture toughness to multiscale microstructures in a realistic 3D numerical model in a direct manner is accomplished. (author)

Stress Fractures

Science.gov (United States)

Stress fractures Overview Stress fractures are tiny cracks in a bone. They're caused by repetitive force, often from overuse — such as repeatedly jumping up and down or running long distances. Stress fractures can also arise from normal use of ...

Delivery by Cesarean Section is not Associated With Decreased at-Birth Fracture Rates in Osteogenesis Imperfecta

Science.gov (United States)

Bellur, S; Jain, M; Cuthbertson, D; Krakow, D; Shapiro, JR; Steiner, RD; Smith, PA; Bober, MB; Hart, T; Krischer, J; Mullins, M; Byers, PH; Pepin, M; Durigova, M; Glorieux, FH; Rauch, F; Sutton, VR; Lee, B; Nagamani, SC

2015-01-01

Purpose Osteogenesis imperfecta (OI) predisposes to recurrent fractures. The moderate-to-severe forms of OI present with antenatal fractures and the mode of delivery that would be safest for the fetus is not known. Methods We conducted systematic analyses on the largest cohort of individuals (n=540) with OI enrolled to-date in the OI Linked Clinical Research Centers. Self-reported at-birth fracture rates were compared in individuals with OI types I, III, and IV. Multivariate analyses utilizing backward-elimination logistic regression model building were performed to assess the effect of multiple covariates including method of delivery on fracture-related outcomes. Results When accounting for other covariates, at-birth fracture rates did not differ based on whether delivery was by vaginal route or by cesarean section (CS). Increased birth weight conferred higher risk for fractures irrespective of the delivery method. In utero fracture, maternal history of OI, and breech presentation were strong predictors for choosing CS for delivery. Conclusion Our study, the largest to analyze the effect of various factors on at-birth fracture rates in OI shows that delivery by CS is not associated with decreased fracture rate. With the limitation that the fracture data were self-reported in this cohort, these results suggest that CS should be performed only for other maternal or fetal indications, but not for the sole purpose of fracture prevention in OI. PMID:26426884

Transstyloid, transscaphoid, transcapitate fracture: a variant of scaphocapitate fractures.

LENUS (Irish Health Repository)

Burke, Neil G

2014-01-01

Transstyloid, transscaphoid, transcapitate fractures are uncommon. We report the case of a 28-year-old man who sustained this fracture following direct trauma. The patient was successfully treated by open reduction internal fixation of the scaphoid and proximal capitate fragment, with a good clinical outcome at 1-year follow-up. This pattern is a new variant of scaphocapitate fracture as involves a fracture of the radial styloid as well.

Quantifying water flow and retention in an unsaturated fracture-facial domain

Science.gov (United States)

Nimmo, John R.; Malek-Mohammadi, Siamak

2015-01-01

Hydrologically significant flow and storage of water occur in macropores and fractures that are only partially filled. To accommodate such processes in flow models, we propose a three-domain framework. Two of the domains correspond to water flow and water storage in a fracture-facial region, in addition to the third domain of matrix water. The fracture-facial region, typically within a fraction of a millimeter of the fracture wall, includes a flowing phase whose fullness is determined by the availability and flux of preferentially flowing water, and a static storage portion whose fullness is determined by the local matric potential. The flow domain can be modeled with the source-responsive preferential flow model, and the roughness-storage domain can be modeled with capillary relations applied on the fracture-facial area. The matrix domain is treated using traditional unsaturated flow theory. We tested the model with application to the hydrology of the Chalk formation in southern England, coherently linking hydrologic information including recharge estimates, streamflow, water table fluctuation, imaging by electron microscopy, and surface roughness. The quantitative consistency of the three-domain matrix-microcavity-film model with this body of diverse data supports the hypothesized distinctions and active mechanisms of the three domains and establishes the usefulness of this framework.

Distinct Fracture Patterns in Construction Steels for Reinforced Concrete under Quasistatic Loading— A Review

Directory of Open Access Journals (Sweden)

Fernando Suárez

2018-03-01

Full Text Available Steel is one of the most widely used materials in construction. Nucleation growth and coalescence theory is usually employed to explain the fracture process in ductile materials, such as many metals. The typical cup–cone fracture pattern has been extensively studied in the past, giving rise to numerical models able to reproduce this pattern. Nevertheless, some steels, such as the eutectoid steel used for manufacturing prestressing wires, does not show this specific shape but a flat surface with a dark region in the centre of the fracture area. Recent studies have deepened the knowledge on these distinct fracture patterns, shedding light on some aspects that help to understand how damage begins and propagates in each case. The numerical modelling of both fracture patterns have also been discussed and reproduced with different approaches. This work reviews the main recent advances in the knowledge on this subject, particularly focusing on the experimental work carried out by the authors.

Advancements in mass spectrometry for biological samples: Protein chemical cross-linking and metabolite analysis of plant tissues

Energy Technology Data Exchange (ETDEWEB)

Klein, Adam [Iowa State Univ., Ames, IA (United States)

2015-01-01

This thesis presents work on advancements and applications of methodology for the analysis of biological samples using mass spectrometry. Included in this work are improvements to chemical cross-linking mass spectrometry (CXMS) for the study of protein structures and mass spectrometry imaging and quantitative analysis to study plant metabolites. Applications include using matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) to further explore metabolic heterogeneity in plant tissues and chemical interactions at the interface between plants and pests. Additional work was focused on developing liquid chromatography-mass spectrometry (LC-MS) methods to investigate metabolites associated with plant-pest interactions.

Conductivity Evolution of Fracture Proppant in Partial Monolayers and Multilayers

Science.gov (United States)

Fan, M.; Han, Y.; McClure, J. E.; Chen, C.

2017-12-01

Proppant is a granular material, typically sand, coated sand, or man-made ceramic materials, which is widely used in hydraulic fracturing to keep the induced fractures open. Optimization of proppant placement in a hydraulic fracture, as well as its role on the fracture's conductivity, is vital for effective and economical production of petroleum hydrocarbons. In this research, a numerical modeling approach, combining Discrete Element Method (DEM) with lattice Boltzmann (LB) method, was adopted to advance the understanding of fracture conductivity as function of proppant concentration under various effective stresses. DEM was used to simulate effective stress increase and the resultant proppant particle compaction and rearrangement during the process of reservoir depletion due to hydrocarbon extraction. DEM-simulated pore structure was extracted and imported into the LB simulator as boundary conditions to calculate the time-dependent permeability of the proppant pack. We first validated the DEM-LB coupling workflow; the simulated proppant pack permeabilities as functions of effective stress were in good agreement with laboratory measurements. Next, several proppant packs were generated with various proppant concentrations, ranging from partial-monolayer to multilayer structures. Proppant concentration is defined as proppant mass per unit fracture face area. Fracture conductivity as function of proppant concentration was measured in LB simulations. It was found that a partial-monolayer proppant pack with large-diameter particles was optimal in maintaining sufficient conductivity while lowering production costs. Three proppant packs with the same average diameter but different diameter distributions were generated. Specifically, we used the coefficient of variation (COV) of diameter, defined as the ratio of standard deviation of diameter to mean diameter, to characterize the heterogeneity in particle size. We obtained proppant pack porosity, permeability, and fracture

Risk of hip fracture after osteoporosis fractures. 451 women with fracture of lumbar spine, olecranon, knee or ankle

DEFF Research Database (Denmark)

Lauritzen, J B; Lund, B

1993-01-01

In a follow-up study during 1976-1984, the risk of a subsequent hip fracture was investigated in women aged 60-99 years, hospitalized for the following fractures: lumbar spine (n 70), olecranon (n 52), knee (n 129) and ankle (n 200). Follow-up ranged from 0 to 9 years. Observation time of the 4...... different fractures were 241, 180, 469, and 779, person-years, respectively. In women aged 60-79 years with one of the following fractures the relative risk of a subsequent hip fracture was increased by 4.8 (lumbar spine), 4.1 (olecranon), 3.5 (knee) and 1.5 (ankle). The relative risk of hip fracture showed...... a tendency to level off 3 years after the primary fracture....

The impact of fragility fracture and approaches to osteoporosis risk assessment worldwide.

Science.gov (United States)

Curtis, Elizabeth M; Moon, Rebecca J; Harvey, Nicholas C; Cooper, Cyrus

2017-11-01

Osteoporosis constitutes a major public health problem, through its association with age-related fractures, particularly of the hip, vertebrae, distal forearm and humerus. Substantial geographic variation has been noted in the incidence of osteoporotic fractures worldwide, with Western populations (North America, Europe and Oceania), reporting increases in hip fracture throughout the second half of the 20th century, with a stabilisation or decline in the last two decades. In developing populations however, particularly in Asia, the rates of osteoporotic fracture appears to be increasing. The massive global burden consequent to osteoporosis means that fracture risk assessment should be a high priority among health measures considered by policy makers. The WHO operational definition of osteoporosis, based on a measurement of bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA), has been used globally since the mid-1990s. However, although this definition identifies those at greatest individual risk of fracture, in the population overall a greater total number of fractures occur in individuals with BMD values above the threshold for osteoporosis diagnosis. A number of web-based tools to enable the inclusion of clinical risk factors, with or without BMD, in fracture prediction algorithms have been developed to improve the identification of individuals at high fracture risk, the most commonly used globally being FRAX®. Access to DXA, osteoporosis risk assessment, case finding and treatment varies worldwide, but despite such advances studies indicate that a minority of men and women at high fracture risk receive treatment. Importantly, research is ongoing to demonstrate the clinical efficacy and cost-effectiveness of osteoporosis case finding and risk assessment strategies worldwide. The huge burden caused by osteoporosis related fractures to individuals, healthcare systems and societies should provide a clear impetus for the progression of such

Segmental fracture of the lumbar spine.

Science.gov (United States)

O'hEireamhoin, Sven; Devitt, Brian; Baker, Joseph; Kiely, Paul; Synnott, Keith

2010-10-01

A case report is presented. To describe a rare, previously undescribed pattern of spinal injury. This seems to be a unique injury with no previously described injuries matching the fracture pattern observed. This is a case report based on the experience of the authors. The discussion includes a short literature review based on pubmed searches. We report the case of a 26-year-old female cyclist involved in a road traffic accident with a truck resulting in complete disruption of the lumbar spine. The cyclist was caught on the inside of a truck turning left and seems to have passed under the rear wheels. She was brought to the local emergency department where, after appropriate resuscitation, trauma survey revealed spinal deformity with complete neurologic deficit below T12 and fractured pubic rami, soft tissue injuries to the perineum and multiple abrasions. Plain radiology showed a segmental fracture dislocation of her lumbar vertebrae, extending from the L1 superior endplate through to L4-L5 disc space. The entire segment was displaced in both anteroposterior and lateral planes. Computed tomography confirmed these injuries and ruled out significant visceral injury. She was transferred to the national spinal unit (author unit), where she underwent reduction and fixation with rods and screws from T9-S1, using one cross-link. After her immediate postoperative recovery, she was referred to the national rehabilitation unit. Although so-called "en bloc" lumbar fractures have been previously described, the authors were unable to find any injury of this degree in the literature. This rare injury seems to show a pattern of spinal injury previously undescribed.

A theory for fracture of polymeric gels

Science.gov (United States)

Mao, Yunwei; Anand, Lallit

2018-06-01

A polymeric gel is a cross-linked polymer network swollen with a solvent. If the concentration of the solvent or the deformation is increased to substantial levels, especially in the presence of flaws, then the gel may rupture. Although various theoretical aspects of coupling of fluid permeation with large deformation of polymeric gels are reasonably well-understood and modeled in the literature, the understanding and modeling of the effects of fluid diffusion on the damage and fracture of polymeric gels is still in its infancy. In this paper we formulate a thermodynamically-consistent theory for fracture of polymeric gels - a theory which accounts for the coupled effects of fluid diffusion, large deformations, damage, and also the gradient effects of damage. The particular constitutive equations for fracture of a gel proposed in our paper, contain two essential new ingredients: (i) Our constitutive equation for the change in free energy of a polymer network accounts for not only changes in the entropy, but also changes in the internal energy due the stretching of the Kuhn segments of the polymer chains in the network. (ii) The damage and failure of the polymer network is taken to occur by chain-scission, a process which is driven by the changes in the internal energy of the stretched polymer chains in the network, and not directly by changes in the configurational entropy of the polymer chains. The theory developed in this paper is numerically implemented in an open-source finite element code MOOSE, by writing our own application. Using this simulation capability we report on our study of the fracture of a polymeric gel, and some interesting phenomena which show the importance of the diffusion of the fluid on fracture response of the gel are highlighted.

High prevalence of simultaneous rib and vertebral fractures in patients with hip fracture.

Science.gov (United States)

Lee, Bong-Gun; Sung, Yoon-Kyoung; Kim, Dam; Choi, Yun Young; Kim, Hunchul; Kim, Yeesuk

2017-02-01

The purpose was to evaluate the prevalence and location of simultaneous fracture using bone scans in patients with hip fracture and to determine the risk factors associated with simultaneous fracture. One hundred eighty two patients with hip fracture were reviewed for this study. Clinical parameters and bone mineral density (BMD) of the lumbar vertebra and femoral neck were investigated. To identify acute simultaneous fracture, a bone scan was performed at 15.4±4.1days after hip fracture. The prevalence and location of simultaneous fracture were evaluated, and multivariate logistic regression analysis was performed to determine the risk factors. Simultaneous fracture was observed in 102 of 182 patients, a prevalence of 56.0%. Rib fracture was the most common type of simultaneous fracture followed by rib with vertebral fracture. The BMD of the lumbar vertebra was significantly lower in patients with simultaneous fracture (p=0.044) and was identified as an independent risk factor (odds ratio: OR 0.05, 95% confidence interval: CI 0.01-0.57). The prevalence of simultaneous fracture was relatively high among patients with hip fracture, and BMD was significantly lower in patients with simultaneous fracture than in patients without it. Surgeons should be aware of the possibility of simultaneous fracture in patients with hip fracture. Copyright © 2016 Elsevier Ltd. All rights reserved.

Microstructural Evolution and Fracture Behavior of Friction-Stir-Welded Al-Cu Laminated Composites

Science.gov (United States)

Beygi, R.; Kazeminezhad, Mohsen; Kokabi, A. H.

2014-01-01

In this study, we attempt to characterize the microstructural evolution during friction stir butt welding of Al-Cu-laminated composites and its effect on the fracture behavior of the joint. Emphasis is on the material flow and particle distribution in the stir zone. For this purpose, optical microscopy and scanning electron microscopy (SEM) images, energy-dispersive spectroscopy EDS and XRD analyses, hardness measurements, and tensile tests are carried out on the joints. It is shown that intermetallic compounds exist in lamellas of banding structure formed in the advancing side of the welds. In samples welded from the Cu side, the banding structure in the advancing side and the hook formation in the retreating side determine the fracture behavior of the joint. In samples welded from the Al side, a defect is formed in the advancing side of the weld, which is attributed to insufficient material flow. It is concluded that the contact surface of the laminate (Al or Cu) with the shoulder of the FSW tool influences the material flow and microstructure of welds.

External fixation of tibial pilon fractures and fracture healing.

Science.gov (United States)

Ristiniemi, Jukka

2007-06-01

Distal tibial fractures are rare and difficult to treat because the bones are subcutaneous. External fixation is commonly used, but the method often results in delayed union. The aim of the present study was to find out the factors that affect fracture union in tibial pilon fractures. For this purpose, prospective data collection of tibial pilon fractures was carried out in 1998-2004, resulting in 159 fractures, of which 83 were treated with external fixation. Additionally, 23 open tibial fractures with significant > 3 cm bone defect that were treated with a staged method in 2000-2004 were retrospectively evaluated. The specific questions to be answered were: What are the risk factors for delayed union associated with two-ring hybrid external fixation? Does human recombinant BMP-7 accelerate healing? What is the role of temporary ankle-spanning external fixation? What is the healing potential of distal tibial bone loss treated with a staged method using antibiotic beads and subsequent autogenous cancellous grafting compared to other locations of the tibia? The following risk factors for delayed healing after external fixation were identified: post-reduction fracture gap of >3 mm and fixation of the associated fibula fracture. Fracture displacement could be better controlled with initial temporary external fixation than with early definitive fixation, but it had no significant effect on healing time, functional outcome or complication rate. Osteoinduction with rhBMP-7 was found to accelerate fracture healing and to shorten the sick leave. A staged method using antibiotic beads and subsequent autogenous cancellous grafting proved to be effective in the treatment of tibial bone loss. Healing potential of the bone loss in distal tibia was at least equally good as in other locations of the tibia.

Radiographic anatomy of the proximal femur: femoral neck fracture vs. transtrochanteric fracture

Directory of Open Access Journals (Sweden)

Ana Lecia Carneiro Leão de Araújo Lima

Full Text Available ABSTRACT OBJECTIVE: To evaluate the correlation between radiographic parameters of the proximal femur with femoral neck fractures or transtrochanteric fractures. METHODS: Cervicodiaphyseal angle (CDA, femoral neck width (FNW, hip axis length (HAL, and acetabular tear drop distance (ATD were analyzed in 30 pelvis anteroposterior view X-rays of patients with femoral neck fractures (n = 15 and transtrochanteric fractures (n = 15. The analysis was performed by comparing the results of the X-rays with femoral neck fractures and with transtrochanteric fractures. RESULTS: No statistically significant differences between samples were observed. CONCLUSION: There was no correlation between radiographic parameters evaluated and specific occurrence of femoral neck fractures or transtrochanteric fractures.

Prior nonhip limb fracture predicts subsequent hip fracture in institutionalized elderly people.

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Nakamura, K; Takahashi, S; Oyama, M; Oshiki, R; Kobayashi, R; Saito, T; Yoshizawa, Y; Tsuchiya, Y

2010-08-01

This 1-year cohort study of nursing home residents revealed that historical fractures of upper limbs or nonhip lower limbs were associated with hip fracture (hazard ratio = 2.14), independent of activities of daily living (ADL), mobility, dementia, weight, and type of nursing home. Prior nonhip fractures are useful for predicting of hip fracture in institutional settings. The aim of this study was to evaluate the utility of fracture history for the prediction of hip fracture in nursing home residents. This was a cohort study with a 1-year follow-up. Subjects were 8,905 residents of nursing homes in Niigata, Japan (mean age, 84.3 years). Fracture histories were obtained from nursing home medical records. ADL levels were assessed by caregivers. Hip fracture diagnosis was based on hospital medical records. Subjects had fracture histories of upper limbs (5.0%), hip (14.0%), and nonhip lower limbs (4.6%). Among historical single fractures, only prior nonhip lower limbs significantly predicted subsequent fracture (adjusted hazard ratio, 2.43; 95% confidence interval (CI), 1.30-4.57). The stepwise method selected the best model, in which a combined historical fracture at upper limbs or nonhip lower limbs (adjusted hazard ratio, 2.14; 95% CI, 1.30-3.52), dependence, ADL levels, mobility, dementia, weight, and type of nursing home independently predicted subsequent hip fracture. A fracture history at upper or nonhip lower limbs, in combination with other known risk factors, is useful for the prediction of future hip fracture in institutional settings.

Mandible Fractures.

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Pickrell, Brent B; Serebrakian, Arman T; Maricevich, Renata S

2017-05-01

Mandible fractures account for a significant portion of maxillofacial injuries and the evaluation, diagnosis, and management of these fractures remain challenging despite improved imaging technology and fixation techniques. Understanding appropriate surgical management can prevent complications such as malocclusion, pain, and revision procedures. Depending on the type and location of the fractures, various open and closed surgical reduction techniques can be utilized. In this article, the authors review the diagnostic evaluation, treatment options, and common complications of mandible fractures. Special considerations are described for pediatric and atrophic mandibles.

Advancing New 3D Seismic Interpretation Methods for Exploration and Development of Fractured Tight Gas Reservoirs

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James Reeves

2005-01-31

In a study funded by the U.S. Department of Energy and GeoSpectrum, Inc., new P-wave 3D seismic interpretation methods to characterize fractured gas reservoirs are developed. A data driven exploratory approach is used to determine empirical relationships for reservoir properties. Fractures are predicted using seismic lineament mapping through a series of horizon and time slices in the reservoir zone. A seismic lineament is a linear feature seen in a slice through the seismic volume that has negligible vertical offset. We interpret that in regions of high seismic lineament density there is a greater likelihood of fractured reservoir. Seismic AVO attributes are developed to map brittle reservoir rock (low clay) and gas content. Brittle rocks are interpreted to be more fractured when seismic lineaments are present. The most important attribute developed in this study is the gas sensitive phase gradient (a new AVO attribute), as reservoir fractures may provide a plumbing system for both water and gas. Success is obtained when economic gas and oil discoveries are found. In a gas field previously plagued with poor drilling results, four new wells were spotted using the new methodology and recently drilled. The wells have estimated best of 12-months production indicators of 2106, 1652, 941, and 227 MCFGPD. The latter well was drilled in a region of swarming seismic lineaments but has poor gas sensitive phase gradient (AVO) and clay volume attributes. GeoSpectrum advised the unit operators that this location did not appear to have significant Lower Dakota gas before the well was drilled. The other three wells are considered good wells in this part of the basin and among the best wells in the area. These new drilling results have nearly doubled the gas production and the value of the field. The interpretation method is ready for commercialization and gas exploration and development. The new technology is adaptable to conventional lower cost 3D seismic surveys.

Prevention of non-ductile fracture in 6061-T6 aluminum nuclear pressure vessels

International Nuclear Information System (INIS)

Yahr, G.T.

1995-01-01

The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Committee has approved rules for the use of 6061-T6 and 6061-T651 aluminum for the construction of Class 1 welded nuclear pressure vessels for temperatures not exceeding 149 C (300 F). Nuclear Code Case N-519 allows the use of this aluminum in the construction of low temperature research reactors such as the Advanced Neutron Source. The rules for protection against non-ductile fracture are discussed. The basis for a value of 25.3 MPa √m (23 ksi √in.) for the critical or reference stress intensity factor for use in the fracture analysis is presented. Requirements for consideration of the effects of neutron irradiation on the fracture toughness are discussed

Retrospective Analysis of 513 Cases Diagnosed with Rib Fracture Secondary to Blunt Thorax Trauma

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Serdar Ozkan

2017-05-01

Full Text Available Aim: This study aimed to analyze blunt chest trauma cases who were diagnosed with rib fracture and to examine the regional differences likely to appear in trauma cases and treatment approaches. Material and Method: 513 cases who applied to the Emergency Service and Department of Thoracic Surgery between October 2013 and December 2014 due to blunt trauma and were diagnosed with rib fracture were retrospectively examined. The cases were evaluated in terms of etiological factors, thoracic, and other system injuries accompanying the rib fracture, prognosis, and the treatments applied. Results: Isolated rib fracture was present in 266 of the cases. Thoracic organ injuries such as pneumothorax, hemothorax, hemopneumothorax, lung contusion, or laceration and sternal fracture accompanying the rib fracture were present in 247 of the cases. While one or two rib fractures were detected in 298 cases, six or more rib fractures were present in 28 cases. 78.2% of hemothorax cases, 85.3% of pneumothorax cases, 95.4% of hemopneumothorax cases, 81.8% of bilateral pneumothorax cases, 26% of bilateral hemothorax cases, and 71.4% of bilateral hemopneumothorax cases were treated by applying tube thoracostomy. 129 cases diagnosed with thoracic organ injury in addition to rib fracture but not subjected to surgical intervention, and 266 cases diagnosed with isolated rib fracture were discharged with full recovery after appropriate medical treatment. Discussion: Most of the rib fractures occurring due to blunt trauma are treated successfully with medical treatments and conservative approaches and do not need advanced surgical treatments.

Recognizing and reporting vertebral fractures: reducing the risk of future osteoporotic fractures

International Nuclear Information System (INIS)

Lentle, B.C.; Brown, J.P.; Khan, A.

2007-01-01

Given the increasing evidence that vertebral fractures are underdiagnosed and not acted on, Osteoporosis Canada and the Canadian Association of Radiologists initiated a project to develop and publish a set of recommendations to promote and facilitate the diagnosis and reporting of vertebral fractures. The identification of spinal fractures is not uniform. More than 65% of vertebral fractures cause no symptoms. It is also apparent that vertebral fractures are inadequately recognized when the opportunity for diagnosis arises fortuitously. It is to patients' benefit that radiologists report vertebral fractures evident on a chest or other radiograph, no matter how incidental to the immediate clinical indication for the examination. The present recommendations can help to close the gap in care in recognizing and treating vertebral fractures, to prevent future fractures and thus reduce the burden of osteoporosis-related morbidity and mortality, as well as fracture-related costs to the health care system. Several studies indicate that a gap exists in regard to the diagnosis of vertebral fractures and the clinical response following such diagnosis. All recommendations presented here are based on consensus. These recommendations were developed by a multidisciplinary working group under the auspices of the Scientific Advisory Council of Osteoporosis Canada and the Canadian Association of Radiologists. Prevalent vertebral fractures have important clinical implications in terms of future fracture risk. Recognizing and reporting fractures incidental to radiologic examinations done for other reasons has the potential to reduce health care costs by initiating further steps in osteoporosis diagnosis and appropriate therapy. Physicians should be aware of the importance of vertebral fracture diagnosis in assessing future osteoporotic fracture risk. Vertebral fractures incidental to radiologic examinations done for other reasons should be identified and reported. Vertebral fractures

Advanced Heterogeneous Fenton Treatment of Coalbed Methane-Produced Water Containing Fracturing Fluid

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Meng Zhang

2018-04-01

Full Text Available This study investigated the heterogeneous Fenton treatment to process coalbed methane-produced water containing fracturing fluid and chose the development region of coalbed methane in the Southern Qinshui Basin as a research area. We synthesized the catalyst of Fe-Co/γ-Al2O3 by homogeneous precipitation method and characterized it by BET, XRD, SEM-EDS, FTIR, and XPS. Based on the degradation rate, we studied the influences of the heterogeneous Fenton method on the coalbed methane output water treatment process parameters, including initial pH, H2O2 concentration, and the catalyst concentration. We also investigated the impacts of overall reaction kinetics of heterogeneous catalytic oxidation on coalbed methane-produced water containing fracturing fluid. Results showed that Fe-Co/γ-Al2O3 as a Fenton catalyst has a good catalytic oxidation effect and can effectively process coalbed methane-produced water. This reaction also followed first-order kinetics. The optimal conditions were as follows: the initial pH of 3.5, a H2O2 concentration of 40 mol L−1, a catalyst concentration of 4 g/L, and an apparent reaction rate constant of 0.0172 min−1. Our results provided a basis to establish methods for treating coalbed methane-produced water.

An overview of hydraulic fracturing and other formation stimulation technologies for shale gas production - Update 2015

OpenAIRE

GANDOSSI Luca; VON ESTORFF Ulrik

2015-01-01

The technology of hydraulic fracturing for hydrocarbon well stimulation is not new, but only fairly recently has become a very common and widespread technique, especially in North America, due to technological advances that have allowed extracting natural gas from so-called unconventional reservoirs (tight sands, coal beds and shale formations). The conjunction of techniques such as directional drilling, high volume fracturing, micro-seismic monitoring, etc. with the development of multi-well...

Viscoplasticity and the dynamics of brittle fracture

International Nuclear Information System (INIS)

Langer, J. S.

2000-01-01

I propose a model of fracture in which the curvature of the crack tip is a relevant dynamical variable and crack advance is governed solely by plastic deformation of the material near the tip. This model is based on a rate-and-state theory of plasticity introduced in earlier papers by Falk, Lobkovsky, and myself. In the approximate analysis developed here, fracture is brittle whenever the plastic yield stress is nonzero. The tip curvature finds a stable steady-state value at all loading strengths, and the tip stress remains at or near the plastic yield stress. The crack speed grows linearly with the square of the effective stress intensity factor above a threshold that depends on the surface tension. This result provides a possible answer to the fundamental question of how breaking stresses are transmitted through plastic zones near crack tips. (c) 2000 The American Physical Society

Advanced TCA BAckplane Tester

CERN Document Server

Oltean, Alexandra Dana; PGNet2005

2005-01-01

The “Advanced Telecom Computing Architecture” (AdvancedTCA) is a modular standard chassis based system designed to support the needs of carrier class telecommunication applications. It is defined by a set of industry standards under the direction of the PICMG group. One early deployment of the standard technology has been a 10 Gigabit Ethernet switch developed in the framework of the EU funded ESTA project. In order to study the practical aspects of high speed Ethernet switching at 10 Gigabit and above and to validate the signal integrity of the AdvancedTCA backplane, we developed a Backplane Tester. This system is able to run pseudo-random bit sequence (PRBS) traffic at 3.125 Gbps over every link on the AdvancedTCA backplane simultaneously, and to monitor any possible connectivity failure immediately in terms of the link and slot positions inside the chassis. In this paper, we describe the design and the practical architectural hardware and software aspects of the AdvancedTCA Backplane Tester. We also pr...

Simulation of complex fracture networks influenced by natural fractures in shale gas reservoir

Directory of Open Access Journals (Sweden)

Zhao Jinzhou

2014-10-01

Full Text Available When hydraulic fractures intersect with natural fractures, the geometry and complexity of a fracture network are determined by the initiation and propagation pattern which is affected by a number of factors. Based on the fracture mechanics, the criterion for initiation and propagation of a fracture was introduced to analyze the tendency of a propagating angle and factors affecting propagating pressure. On this basis, a mathematic model with a complex fracture network was established to investigate how the fracture network form changes with different parameters, including rock mechanics, in-situ stress distribution, fracture properties, and frac treatment parameters. The solving process of this model was accelerated by classifying the calculation nodes on the extending direction of the fracture by equal pressure gradients, and solving the geometrical parameters prior to the iteration fitting flow distribution. With the initiation and propagation criterion as the bases for the propagation of branch fractures, this method decreased the iteration times through eliminating the fitting of the fracture length in conventional 3D fracture simulation. The simulation results indicated that the formation with abundant natural fractures and smaller in-situ stress difference is sufficient conditions for fracture network development. If the pressure in the hydraulic fractures can be kept at a high level by temporary sealing or diversion, the branch fractures will propagate further with minor curvature radius, thus enlarging the reservoir stimulation area. The simulated shape of fracture network can be well matched with the field microseismic mapping in data point range and distribution density, validating the accuracy of this model.

Fracture in Kaolinite clay suspensions

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Kosgodagan Acharige, Sebastien; Jerolmack, Douglas J.; Arratia, Paulo E.

2017-11-01

Clay minerals are involved in many natural (landslides, river channels) and industrial processes (ceramics, cosmetics, oil recovery). They are plate shaped charged colloids and exhibit different flow properties than simpler colloids when suspended in a liquid such as thixotropy and shear-banding. kaolinite platelets are non-swelling, meaning that the stacks formed by the platelets do not have water layers, and thus the suspension does not have a sol-gel transition. However, it has been shown that kaolinite suspensions possesses a non-zero yield stress even at low concentrations, indicating that the particles arrange themselves in a structure through attractive interactions. Here, we experimentally investigate the sedimentation of kaolinite suspensions in a Hele-Shaw cell. The sedimentation of these dilute suspensions can display solid behavior like fracture, revealed in cross-polarized light, which is linked to the failure of the weakly-bonded structure (typical yield stress 10-2 Pa). By changing the interaction potential of the particles (by sonication or introducing salts), we show through these sedimentation experiments, how the fracture pattern can be avoided. Research was sponsored by the Army Research Laboratory and was accomplished under Grant Number 569074.

Skull wounds linked with blunt trauma (hammer example). A report of two depressed skull fractures--elements of biomechanical explanation.

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Delannoy, Yann; Becart, Anne; Colard, Thomas; Delille, Rémi; Tournel, Gilles; Hedouin, Valéry; Gosset, Didier

2012-09-01

The lesions of the skull following perforating traumas can create complex fractures. The blunt traumas can, according to the swiftness and the shape of the object used, create a depressed fracture. The authors describe through two clinical cases the lesional characteristic of the blunt traumas, perforating the skull using a hammer. In both cases the cranial lesions were very typical: they were geometrical, square shaped, of the same size than the tool (head and tip of the hammer). On the outer table of the skull, the edges of the wounds were sharp and regular. On the inner table, the edges of the wounds were beveled and irregular. The bony penetration in the depressed fracture results from a rupture of the outer table of the bone under tension, in periphery, by the bend of the bone to the impact (outbending) and then, from the inner table with comminuted bony fragmentation. Breeding on the fractures of the size and the shape of the blunt objects used is inconstant and differs, that it is the objects of flat surface or wide in opposition to those of small surface area. Fractures morphologies depend on one hand on these extrinsic factors and on the other hand, of intrinsic factors (structure of the bone). To identify them, we had previously conducted experimental work on cranial bone samples. The bone was submitted to a device for three-point bending. This work had shown properties of thickness and stiffness of the various areas of the vault. Our cases are consistent with these results and illustrate the variability of bone lesions according to region and mode of use of blunt weapons. Many studies have identified criteria for identification of the weapons and the assistance of digital and biomechanical models will be an invaluable contribution with this aim in the future. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Emergency ultrasound in the detection of pediatric long-bone fractures.

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Barata, Isabel; Spencer, Robert; Suppiah, Ara; Raio, Christopher; Ward, Mary Frances; Sama, Andrew

2012-11-01

Long-bone fractures represent one of the most commonly sustained injuries following trauma and account for nearly 4% of emergency department visits in the United States each year. These fractures are associated with a significant risk of bleeding and neurovascular compromise. Delays in their identification and treatment can lead to loss of limb and even death. Although emergency physicians currently rely predominantly on radiography for the examination of long-bone injuries, emergency ultrasound has several advantages over radiography and may be useful in the identification of long-bone fractures. Ultrasound is rapid, noninvasive, and cost-effective. Unlike radiography, ultrasound does not expose children to ionizing radiation, which has been linked to cancer. The goal of this study was to assess the agreement between emergency physicians' and radiologists' final assessments of suspected long-bone fractures using emergency ultrasound and radiography, respectively, in the pediatric population. This is a prospective study involving a convenience sample of pediatric patients (fracture. Suspected fractures were characterized by swelling, erythema, and localized pain. Patients who had a history of fracture, extremity deformity, orthopedic hardware in the traumatized area, or an open fracture were excluded from this study. Each investigator received limited, focused training in the use of ultrasonography for fracture identification and localization. This training consisted of a brief didactic session and video review of normal and fractured long-bones. A total of 53 subjects (mean age, 10.2 [SD, 3.8] years; 56.6% were male) were enrolled, which corresponded to 98 ultrasound examinations. Sixty-nine scans (70.4%) involved bones of the upper extremity, and 29 (29.6%) the lower extremity. Radiography identified a total of 43 fractures. The sensitivity and specificity of ultrasound in the detection of long-bone fractures were 95.3% (95% confidence interval [CI], 82

Global burden of trauma: Need for effective fracture therapies

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Mathew George

2009-01-01

Full Text Available Orthopedic trauma care and fracture management have advanced significantly over the last 50 years. New developments in the biology and biomechanics of the musculoskeletal system, fixation devices, and soft tissue management have greatly influenced our ability to care for musculoskeletal injuries. Many therapies and treatment modalities have the potential to transform future orthopedic treatment by decreasing invasive procedures and providing shorter healing times. Promising results in experimental models have led to an increase in clinical application of these therapies in human subjects. However, for many modalities, precise clinical indications, timing, dosage, and mode of action still need to be clearly defined. In order to further develop fracture management strategies, predict outcomes and improve clinical application of newer technologies, further research studies are needed. Together with evolving new therapies, the strategies to improve fracture care should focus on cost effectiveness. This is a great opportunity for the global orthopedic community, in association with other stakeholders, to address the many barriers to the delivery of safe, timely, and effective care for patients with musculoskeletal injuries in developing countries.

Structural heritage, reactivation and distribution of fault and fracture network in a rifting context: Case study of the western shoulder of the Upper Rhine Graben

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Bertrand, Lionel; Jusseaume, Jessie; Géraud, Yves; Diraison, Marc; Damy, Pierre-Clément; Navelot, Vivien; Haffen, Sébastien

2018-03-01

In fractured reservoirs in the basement of extensional basins, fault and fracture parameters like density, spacing and length distribution are key properties for modelling and prediction of reservoir properties and fluids flow. As only large faults are detectable using basin-scale geophysical investigations, these fine-scale parameters need to be inferred from faults and fractures in analogous rocks at the outcrop. In this study, we use the western shoulder of the Upper Rhine Graben as an outcropping analogue of several deep borehole projects in the basement of the graben. Geological regional data, DTM (Digital Terrain Model) mapping and outcrop studies with scanlines are used to determine the spatial arrangement of the faults from the regional to the reservoir scale. The data shows that: 1) The fault network can be hierarchized in three different orders of scale and structural blocks with a characteristic structuration. This is consistent with other basement rocks studies in other rifting system allowing the extrapolation of the important parameters for modelling. 2) In the structural blocks, the fracture network linked to the faults is linked to the interplay between rock facies variation linked to the rock emplacement and the rifting event.

[Trochanteric femoral fractures].

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Douša, P; Čech, O; Weissinger, M; Džupa, V

2013-01-01

At the present time proximal femoral fractures account for 30% of all fractures referred to hospitals for treatment. Our population is ageing, the proportion of patients with post-menopausal or senile osteoporosis is increasing and therefore the number of proximal femoral fractures requiring urgent treatment is growing too. In the age category of 50 years and older, the incidence of these fractures has increased exponentially. Our department serves as a trauma centre for half of Prague and part of the Central Bohemia Region with a population of 1 150 000. Prague in particular has a high number of elderly citizens. Our experience is based on extensive clinical data obtained from the Register of Proximal Femoral Fractures established in 1997. During 14 years, 4280 patients, 3112 women and 1168 men, were admitted to our department for treatment of proximal femoral fractures. All patients were followed up until healing or development of complications. In the group under study, 82% were patients older than 70 years; 72% of those requiring surgery were in their seventies and eighties. Men were significantly younger than women (pfractures were 2.3-times more frequent in women than in men. In the category under 60 years, men significantly outnumbered women (pfractures were, on the average, eight years older than the patients with intertrochanteric fractures, which is a significant difference (pTrochanteric fractures accounted for 54.7% and femoral neck fractures for 45.3% of all fractures. The inter-annual increase was 5.9%, with more trochanteric than femoral neck fractures. There was a non-significant decrease in intertrochanteric (AO 31-A3) fractures. On the other hand, the number of pertrochanteric (AO 31-A1+2) fractures increased significantly (pfractures were treated with a proximal femoral nail; a short nail was used in 1260 and a long nail in 134 of them. A dynamic hip screw (DHS) was employed to treat 947 fractures. Distinguishing between pertrochanteric (21-A1

Jogger's fracture and other stress fractures of the lumbo-sacral spine

International Nuclear Information System (INIS)

Abel, M.S.

1985-01-01

The posterior rings of the lower lumbo-sacral vertebrae are subject to stress fractures at any part - pedicle, pars, or lamina. The site of fracture is apparently determined by the axis of weight bearing. The three illustrative clinical examples cited include a jogger with a laminar fracture, a ballet dancer with pedicle fractures, and a nine-year-old boy with fractures of pars and lamina. Chronic low back pain is the typical complaint with stress fractures of the lower lumbo-sacral spine. Special imaging techniques are usually needed to demonstrate these lesions, including vertebral arch views, multi-directional tomography, and computed tomography (CT). (orig.)

Fracture toughness of irradiated stainless steel alloys

International Nuclear Information System (INIS)

Mills, W.J.

1986-01-01

The postirradiation fracture toughness responses of Types 316 and 304 stainless steel (SS) wrought products, cast CF8 SS and Type 308 SS weld deposit were characterized at 427 0 C using J/sub R/-curve techniques. Fast-neutron irradiation of these alloys caused an order of magnitude reduction in J/sub c/ and two orders of magnitude reduction in tearing modulus at neutron exposures above 10 dpa, where radiation-induced losses in toughness appeared to saturate. Saturation J/sub c/ values for the wrought materials ranged from 28 to 31 kJ/m 2 ; the weld exhibited a saturation level of 11 kJ/m 2 . Maximum allowable flaw sizes for highly irradiated stainless steel components stressed to 90% of the unirradiated yield strength are on the order of 3 cm for the wrought material and 1 cm for the weld. Electron fractographic examination revealed that irradiation displacement damage brought about a transition from ductile microvoid coalescence to channel fracture, associated with local separation along planar deformation bands. The lower saturation toughness value for the weld relative to that for the wrought products was attributed to local failure of ferrite particles ahead of the advancing crack which prematurely initiated channel fracture

Imaging of insufficiency fractures

Energy Technology Data Exchange (ETDEWEB)

Krestan, Christian [Department of Radiology, Medical University of Vienna, Vienna General Hospital, Waehringerstr. 18-20, 1090 Vienna (Austria)], E-mail: christian.krestan@meduniwien.ac.at; Hojreh, Azadeh [Department of Radiology, Medical University of Vienna, Vienna General Hospital, Waehringerstr. 18-20, 1090 Vienna (Austria)

2009-09-15

This review focuses on the occurrence, imaging and differential diagnosis of insufficiency fractures. Prevalence, the most common sites of insufficiency fractures and their clinical implications are discussed. Insufficiency fractures occur with normal stress exerted on weakened bone. Postmenopausal osteoporosis is the most common cause of insufficiency fractures. Other conditions which affect bone turnover include osteomalacia, hyperparathyroidism, chronic renal failure and high-dose glucocorticoid therapy. It is a challenge for the radiologist to detect and diagnose insufficiency fractures, and to differentiate them from other bone lesions. Radiographs are still the most widely used imaging method for identification of insufficiency fractures, but sensitivity is limited, depending on the location of the fractures. Magnetic resonance imaging (MRI) is a very sensitive tool to visualize bone marrow abnormalities associated with insufficiency fractures. Thin section, multi-detector computed tomography (MDCT) depicts subtle fracture lines allowing direct visualization of cortical and trabecular bone. Bone scintigraphy still plays a role in detecting fractures, with good sensitivity but limited specificity. The most important differential diagnosis is underlying malignant disease leading to pathologic fractures. Bone densitometry and clinical history may also be helpful in confirming the diagnosis of insufficiency fractures.

Recent advances in environmental monitoring using commercial microwave links

Science.gov (United States)

Alpert, Pinhas; Guez, Oded; Messer, Hagit; David, Noam; Harel, Oz; Eshel, Adam; Cohen, Ori

2016-04-01

Recent advances in environmental monitoring using commercial microwave links Pinhas Alpert, H. Messer, N. David, O. Guez, O. Cohen, O. Harel, A. Eshel Tel Aviv University, Israel The propagation of electromagnetic radiation in the lower atmosphere, at centimeter wavelengths, is impaired by atmospheric conditions. Absorption and scattering of the radiation, at frequencies of tens of GHz, are directly related to the atmospheric phenomena, primarily precipitation, oxygen, mist, fog and water vapor. As was recently shown, wireless communication networks supply high resolution precipitation measurements at ground level while often being situated in flood prone areas, covering large parts of these hazardous regions. On the other hand, at present, there are no satisfactory real time flash flood warning facilities found to cope well with this phenomenon. I will exemplify the flash flood warning potential of the commercial wireless communication system for semi-arid region cases when floods occurred in the Judean desert in Israel with comparison to hydrological measurements in the Dead Sea area. In addition, I will review our recent improvements in monitoring rainfall as well as other-than-rain phenomena like, fog, dew, atmospheric moisture. References: N. David, P. Alpert, and H. Messer, "Technical Note: Novel method for water vapor monitoring using wireless communication networks measurements", Atmos. Chem. Phys., 9, 2413-2418, 2009. A. Rayitsfeld, R. Samuels, A. Zinevich, U. Hadar and P. Alpert,"Comparison of two methodologies for long term rainfall monitoring using a commercial microwave communication system", Atmospheric Research 104-105, 119-127, 2012. N. David, O. Sendik, H. Messer and P. Alpert, "Cellular network infrastructure-the future of fog monitoring?" BAMS (Oct. issue), 1687-1698, 2015. O. Harel, David, N., Alpert, P. and Messer, H., "The potential of microwave communication networks to detect dew using the GLRT- experimental study", IEEE Journal of Selected

Fracture mechanical treatment of bridging stresses in ceramics

International Nuclear Information System (INIS)

Fett, T.; Munz, D.

1993-12-01

Failure of ceramic materials often starts from cracks which can originate at pores, inclusions or can be generated during surface treatment. Fracture occurs when the stress intensity factor of the most serious crack in a component reaches a critical value K lc , the fracture toughness of the material. In case of ideal brittle materials the fracture toughness is independent of the crack extension and, consequently, identical with the stress intensity factor K l0 necessary for the onset of stable crack growth. It is a well-known fact that failure of several ceramics is influenced by an increasing crack-growth resistance curve. Several effects are responsible for this behaviour. Crack-border interactions in the wake of the advancing crack, residual stress fields in the crack region of transformation-toughened ceramics, the generation of a micro-crack zone ahead the crack tip and crack branching. The effect of increasing crack resistance has consequences on many properties of ceramic materials. In this report the authors discuss the some aspects of R-curve behaviour as the representation by stress intensity factors or energies and the influence on the compliance using the bridging stress model. (orig.) [de

Model of mechanical representation of the formation of natural fractures inside a petroleum reservoir; Modele de representation mecanique de la formation des fractures naturelles d'un reservoir petrolier

Energy Technology Data Exchange (ETDEWEB)

Picard, D.

2005-09-15

The optimisation of the oil production requires a better characterisation of naturally fractured reservoirs. We consider and analyse two spatial distributions. One with systematic joints is arranged in an homogeneous way; joint spacing is linked to individual bedding thickness with propagation frequently interrupted by stratigraphic interfaces (single layer jointing). The second, so-called fracture swarms, consists in fractures clustering, where stratigraphic interfaces seem to play a minor role. The analysis is based on the singularity theory and matched asymptotic expansions method with a fine scale for local perturbations and a global one for general trends. We examine the conditions of fracture propagation that are determined herein using simultaneously two fracture criteria an energy and a stress condition. We consider two modes of loading. Usually, the joint (crack opening mode) and fracture swarm growths are explained by a first order phenomenon involving effective traction orthogonal to fracture plane. Although commonly used, this hypothesis seems unrealistic in many circumstances and may conflict with geological observations. Then, we try to describe fracture growth as a second order phenomena resulting from crack parallel compression. As far as propagation across layer interfaces is concerned, the effect of loading and geometry has been summarised in maps of fracture mechanisms, describing areas of 'step-over', 'straight through propagation' and 'crack arrest'. Fracture criteria, relative size of heterogeneities, contrast of mechanical properties between bed and layer are parameters of the problem. For fracture swarms, we present a discussion bringing out what is reasonable as a loading to justify their morphology. In particular, horizontal effective tension is unable to explain neighbouring joints. Simultaneous propagation of parallel near cracks is explained by finite width cracks growing under the influence of vertical

Influence of structures on fracture and fracture toughness of cemented tungsten carbides

International Nuclear Information System (INIS)

Zhao, W.; Zhang, X.

1987-01-01

A study was made of the influence of structures on fracture and fracture toughness of cemented tungsten carbides with different compositions and grain sizes. The measurement of the fracture toughness of cemented tungsten carbide was carried out using single edge notched beam. The microstructural parameters and the proportion for each fracture mode on the fracture surface were obtained. The brittle fracture of the alloy is mainly due to the interfacial decohesion fracture following the interface of the carbide crystals. It has been observed that there are localized fractures region ahead of the crack tip. The morphology of the crack propagation path as well as the slip structure in the cobalt phase of the deformed region have been investigated. In addition, a study of the correlation between the plane strain fracture toughness and microstructural parameters, such as mean free path of the cobalt phase, tungsten carbide grain size and the contiguity of tungsten carbide crystals was also made

The Net Advance of Physics

Science.gov (United States)

THE NET ADVANCE OF PHYSICS Review Articles and Tutorials in an Encyclopædic Format Established 1995 [Link to MIT] Computer support for The Net Advance of Physics is furnished by The Massachusetts Newest Additions SPECIAL FEATURES: Net Advance RETRO: Nineteenth Century Physics History of Science

Rib fractures predict incident limb fractures: results from the European prospective osteoporosis study.

Science.gov (United States)

Ismail, A A; Silman, A J; Reeve, J; Kaptoge, S; O'Neill, T W

2006-01-01

Population studies suggest that rib fractures are associated with a reduction in bone mass. While much is known about the predictive risk of hip, spine and distal forearm fracture on the risk of future fracture, little is known about the impact of rib fracture. The aim of this study was to determine whether a recalled history of rib fracture was associated with an increased risk of future limb fracture. Men and women aged 50 years and over were recruited from population registers in 31 European centres for participation in a screening survey of osteoporosis (European Prospective Osteoporosis Study). Subjects were invited to complete an interviewer-administered questionnaire that included questions about previous fractures including rib fracture, the age of their first fracture and also the level of trauma. Lateral spine radiographs were performed and the presence of vertebral deformity was determined morphometrically. Following the baseline survey, subjects were followed prospectively by annual postal questionnaire to determine the occurrence of clinical fractures. The subjects included 6,344 men, with a mean age of 64.2 years, and 6,788 women, with a mean age of 63.6 years, who were followed for a median of 3 years (range 0.4-5.9 years), of whom 135 men (2.3%) and 101 women (1.6%) reported a previous low trauma rib fracture. In total, 138 men and 391 women sustained a limb fracture during follow-up. In women, after age adjustment, those with a recalled history of low trauma rib fracture had an increased risk of sustaining 'any' limb fracture [relative hazard (RH)=2.3; 95% CI 1.3, 4.0]. When stratified by fracture type the predictive risk was more marked for hip (RH=7.7; 95% CI 2.3, 25.9) and humerus fracture (RH=4.5; 95% CI 1.4, 14.6) than other sites (RH=1.6; 95% CI 0.6, 4.3). Additional adjustment for prevalent vertebral deformity and previous (non-rib) low trauma fractures at other sites slightly reduced the strength of the association between rib fracture and

Discrete fracture network for the Forsmark site

International Nuclear Information System (INIS)

Darcel, C.; Davy, P.; Bour, O.; Dreuzy, J.R. de

2006-08-01

In this report, we aim at defining a self-consistent method for analyzing the fracture patterns from boreholes, outcrops and lineaments. The objective was both to point out some variations in the fracture network parameters, and to define the global scaling fracture models that can encompass all the constraints brought by the different datasets. Although a full description of the DFN model variability is obviously fundamental for the future, we have put emphasis on the determination of mean parameters. The main parameters of the disc-shaped DFN model are the fracture size, orientations and spatial density distribution. The scaling model is defined as an extrapolation of existing i) observations at specific scales and ii) local fitting models to the whole range of scales. The range of possible models is restricted to the power-law scaling models. During the project we have put emphasize on the definition of the theory and methodology necessary to assess a sound comparison between data taken at different scales, with different techniques. Both 'local' and 'global' models have been investigated. Local models are linked exactly to the dataset they represent. Then, the global DFN models arise from the association of local models, different scales and different sample support shapes. Discrepancies between local and global model illustrate the variability associated to the DFN models. We define two possible Global Scaling Models (GSM). The first one is consistent with the scaling measured in the outcrops (Model A). Its scaling exponent is a 3d =3.5 (eq. to k r =2.5); it overestimates the fracture densities observed in the lineament maps. The second one assumes that both lineaments and outcrops belong to the same distribution model (Model B), which entails a scaling exponent a 3d =3.9 (eq. to k r =2.9). Both models have been tested by looking for the best consistency in the fracture density-dip relationships, between boreholes data at depth (based on boreholes KFM02A, KFM

Hip fracture - discharge

Science.gov (United States)

... neck fracture repair - discharge; Trochanteric fracture repair - discharge; Hip pinning surgery - discharge ... in the hospital for surgery to repair a hip fracture, a break in the upper part of ...

Investigation of the local fracture toughness and the elastic-plastic fracture behavior of NiAl and tungsten by means of micro-cantilever tests

International Nuclear Information System (INIS)

Ast, Johannes

2016-01-01

is linked to the thermally activated dislocation mobility which is more constrained in those samples. Investigations on plastically predeformed samples were performed in order to study the influence of the dislocation density on the fracture behavior. It was found that the fracture toughness was again not affected but that the predeformed samples failed at an earlier stage at lower J-integrals. This is due to the lower mobility of the dislocations emitted from the crack tip in consequence of the high amount of strain hardening and the higher flow stress in those samples. Experiments in ultrafine-grained tungsten revealed a fracture behavior which was more brittle than expected. A single grain at the crack front with its crystallographic orientation being prone to cleavage failure can decisively influence the fracture behavior at the micro scale. [de

Vital capacity helps predict pulmonary complications after rib fractures.

Science.gov (United States)

Carver, Thomas W; Milia, David J; Somberg, Chloe; Brasel, Karen; Paul, Jasmeet

2015-09-01

Traumatic rib fractures are associated with significant morbidity. Vital capacity (VC) assesses pulmonary function; however, limited data link VC to patient outcomes. Our objective was to determine if VC predicted complications and disposition in patients with rib fractures. This is a retrospective chart review of all patients with fractured ribs admitted to a Level 1 trauma center during a 4-year period. Patients were excluded if no VC was performed within 48 hours of admission. Data collected included demographics, hospital/intensive care unit length of stay, epidural, discharge to home versus extended care facility, mortality, chest Abbreviated Injury Scale (AIS) score, Injury Severity Score (ISS), number of rib fractures, hemothorax/pneumothorax, presence of pulmonary contusion, presence of chest tube, chronic obstructive pulmonary disease, and average daily VC (percentage of predicted). Pulmonary complication was defined as pneumonia, need for intubation, new home O2 requirement, readmission for pulmonary issue, or intensive care unit transfer. Statistical analysis was performed using χ and multivariate logistic regression. Of 801 patients with rib fractures, 683 had VC performed within 48 hours. Average age was 53 years, median ISS was 13 (interquartile range, 9-18), and median length of stay was 5 days. Most (72%) were discharged home, and 26% went to extended care facility. Ten percent developed a pulmonary complication, and there were nine deaths. Every 10% increase in VC was associated with 36% decrease in likelihood of pulmonary complication. Patients with a VC greater than 50% had a significantly lower association of pulmonary complication (p = 0.017), and a VC of less than 30% was independently associated with pulmonary complication (odds ratio, 2.36). Patients with fractured ribs and VC of less than 30% have significant association for pulmonary complication. Higher VC is associated with lower likelihood of pulmonary complication. VC may help

Hydraulic fracturing tests in anhydrite interbeds in the WIPP, Marker Beds 139 and 140

Energy Technology Data Exchange (ETDEWEB)

Howard, C L [RE/SPEC Inc., Albuquerque, NM (United States); Wawersik, W. R.; Carlson, L. V.; Henfling, J. A.; Borns, D. J.; Beauheim, R. L.; Roberts, R. M.

1997-05-01

Hydraulic fracturing tests were integrated with hydrologic tests to estimate the conditions under which gas pressure in the disposal rooms in the Waste Isolation Pilot Plant, Carlsbad, NM (WIPP) will initiate and advance fracturing in nearby anhydrite interbeds. The measurements were made in two marker beds in the Salado formation, MB139 and MB140, to explore the consequences of existing excavations for the extrapolation of results to undisturbed ground. The interpretation of these measurements is based on the pressure-time records in two injection boreholes and several nearby hydrologic observation holes. Data interpretations were aided by post-test borehole video surveys of fracture traces that were made visible by ultraviolet illumination of fluorescent dye in the hydraulic fracturing fluid. The conclusions of this report relate to the upper- and lower-bound gas pressures in the WIPP, the paths of hydraulically and gas-driven fractures in MB139 and MB140, the stress states in MB139 and MB140, and the probable in situ stress states in these interbeds in undisturbed ground far away from the WIPP.

Quantifying Discrete Fracture Network Connectivity in Hydraulic Fracturing Stimulation

Science.gov (United States)

Urbancic, T.; Ardakani, E. P.; Baig, A.

2017-12-01

Hydraulic fracture stimulations generally result in microseismicity that is associated with the activation or extension of pre-existing microfractures and discontinuities. Microseismic events acquired under 3D downhole sensor coverage provide accurate event locations outlining hydraulic fracture growth. Combined with source characteristics, these events provide a high quality input for seismic moment tensor inversion and eventually constructing the representative discrete fracture network (DFN). In this study, we investigate the strain and stress state, identified fracture orientation, and DFN connectivity and performance for example stages in a multistage perf and plug completion in a North American shale play. We use topology, the familiar concept in many areas of structural geology, to further describe the relationships between the activated fractures and their effectiveness in enhancing permeability. We explore how local perturbations of stress state lead to the activation of different fractures sets and how that effects the DFN interaction and complexity. In particular, we observe that a more heterogeneous stress state shows a higher percentage of sub-horizontal fractures or bedding plane slips. Based on topology, the fractures are evenly distributed from the injection point, with decreasing numbers of connections by distance. The dimensionless measure of connection per branch and connection per line are used for quantifying the DFN connectivity. In order to connect the concept of connectivity back to productive volume and stimulation efficiency, the connectivity is compared with the character of deformation in the reservoir as deduced from the collective behavior of microseismicity using robustly determined source parameters.

Seven years’ experience with etidronate in a woman with anorexia nervosa and vertebral fractures

Directory of Open Access Journals (Sweden)

Iwamoto J

2011-07-01

Full Text Available Jun Iwamoto1, Yoshihiro Sato2, Mitsuyoshi Uzawa3, Tsuyoshi Takeda1, Hideo Matsumoto11Institute for Integrated Sports Medicine, Keio University School of Medicine, Tokyo, Japan; 2Department of Neurology, Mitate Hospital, Fukuoka, Japan; 3Department of Orthopaedic Surgery, Keiyu Orthopaedic Hospital, Gunma, JapanAbstract: We report the case of a 30-year-old Japanese woman with anorexia nervosa and vertebral fractures who was treated with etidronate. She had a history of anorexia nervosa, chronic back pain, osteoporosis, and multiple vertebral fractures (morphometric fractures that responded poorly to treatment with alfacalcidol (1 µg daily for 1 year and was treated with cyclical etidronate (200 mg for 2 weeks every 3 months for 7 years. The lumbar spine bone mineral density (BMD increased, and the serum alkaline phosphatase and urinary cross-linked N-terminal telopeptides of type I collagen levels and back pain decreased. During the 7-year period of treatment with etidronate, no osteoporotic fractures occurred. The patient experienced neither renal dysfunction nor hyperparathyroidism caused by osteomalacia. No gastrointestinal tract symptoms were observed. Thus, etidronate was effective for increasing the lumbar spine BMD and reducing back pain over a 7-year period without causing either osteoporotic fractures or adverse events.Keywords: anorexia nervosa, bulimia, etidronate, bone mineral density, osteoporosis, vertebral fracture

Fracture network growth for prediction of fracture characteristics and connectivity in tight reservoir rocks

NARCIS (Netherlands)

Barnhoorn, A.; Cox, S.F.

2012-01-01

Fracturing experiments on very low-porosity dolomite rocks shows a difference in growth of fracture networks by stress-driven fracturing and fluid-driven fracturing. Stress-driven fracture growth, in the absence of fluid pressure, initially forms fractures randomly throughout the rocks followed by

Scaphoid Fracture

Directory of Open Access Journals (Sweden)

Esther Kim, BS

2018-04-01

Full Text Available History of present illness: A 25-year-old, right-handed male presented to the emergency department with left wrist pain after falling from a skateboard onto an outstretched hand two-weeks prior. He otherwise had no additional concerns, including no complaints of weakness or loss of sensation. On physical exam, there was tenderness to palpation within the anatomical snuff box. The neurovascular exam was intact. Plain films of the left wrist and hand were obtained. Significant findings: The anteroposterior (AP plain film of this patient demonstrates a full thickness fracture through the middle third of the scaphoid (red arrow, with some apparent displacement (yellow lines and subtle angulation of the fracture fragments (blue line. Discussion: The scaphoid bone is the most commonly fractured carpal bone accounting for 70%-80% of carpal fractures.1 Classically, it is sustained following a fall onto an outstretched hand (FOOSH. Patients should be evaluated for tenderness with palpation over the anatomical snuffbox, which has a sensitivity of 100% and specificity of 40%.2 Plain films are the initial diagnostic modality of choice and have a sensitivity of 70%, but are commonly falsely negative in the first two to six weeks of injury (false negative of 20%.3 The Mayo classification organizes scaphoid fractures as involving the proximal, mid, and distal portions of the scaphoid bone with mid-fractures being the most common.3 The proximal scaphoid is highly susceptible to vascular compromise because it depends on retrograde blood flow from the radial artery. Therefore, disruption can lead to serious sequelae including osteonecrosis, arthrosis, and functional impairment. Thus, a low threshold should be maintained for neurovascular evaluation and surgical referral. Patients with non-displaced scaphoid fractures should be placed in a thumb spica splint.3 Patients with even suspected scaphoid fractures should be placed in a thumb spica splint and re

Surrogate-based optimization of hydraulic fracturing in pre-existing fracture networks

Science.gov (United States)

Chen, Mingjie; Sun, Yunwei; Fu, Pengcheng; Carrigan, Charles R.; Lu, Zhiming; Tong, Charles H.; Buscheck, Thomas A.

2013-08-01

Hydraulic fracturing has been used widely to stimulate production of oil, natural gas, and geothermal energy in formations with low natural permeability. Numerical optimization of fracture stimulation often requires a large number of evaluations of objective functions and constraints from forward hydraulic fracturing models, which are computationally expensive and even prohibitive in some situations. Moreover, there are a variety of uncertainties associated with the pre-existing fracture distributions and rock mechanical properties, which affect the optimized decisions for hydraulic fracturing. In this study, a surrogate-based approach is developed for efficient optimization of hydraulic fracturing well design in the presence of natural-system uncertainties. The fractal dimension is derived from the simulated fracturing network as the objective for maximizing energy recovery sweep efficiency. The surrogate model, which is constructed using training data from high-fidelity fracturing models for mapping the relationship between uncertain input parameters and the fractal dimension, provides fast approximation of the objective functions and constraints. A suite of surrogate models constructed using different fitting methods is evaluated and validated for fast predictions. Global sensitivity analysis is conducted to gain insights into the impact of the input variables on the output of interest, and further used for parameter screening. The high efficiency of the surrogate-based approach is demonstrated for three optimization scenarios with different and uncertain ambient conditions. Our results suggest the critical importance of considering uncertain pre-existing fracture networks in optimization studies of hydraulic fracturing.

XFEM modeling of hydraulic fracture in porous rocks with natural fractures

Science.gov (United States)

Wang, Tao; Liu, ZhanLi; Zeng, QingLei; Gao, Yue; Zhuang, Zhuo

2017-08-01

Hydraulic fracture (HF) in porous rocks is a complex multi-physics coupling process which involves fluid flow, diffusion and solid deformation. In this paper, the extended finite element method (XFEM) coupling with Biot theory is developed to study the HF in permeable rocks with natural fractures (NFs). In the recent XFEM based computational HF models, the fluid flow in fractures and interstitials of the porous media are mostly solved separately, which brings difficulties in dealing with complex fracture morphology. In our new model the fluid flow is solved in a unified framework by considering the fractures as a kind of special porous media and introducing Poiseuille-type flow inside them instead of Darcy-type flow. The most advantage is that it is very convenient to deal with fluid flow inside the complex fracture network, which is important in shale gas extraction. The weak formulation for the new coupled model is derived based on virtual work principle, which includes the XFEM formulation for multiple fractures and fractures intersection in porous media and finite element formulation for the unified fluid flow. Then the plane strain Kristianovic-Geertsma-de Klerk (KGD) model and the fluid flow inside the fracture network are simulated to validate the accuracy and applicability of this method. The numerical results show that large injection rate, low rock permeability and isotropic in-situ stresses tend to lead to a more uniform and productive fracture network.

Mortality Following Periprosthetic Proximal Femoral Fractures Versus Native Hip Fractures.

Science.gov (United States)

Boylan, Matthew R; Riesgo, Aldo M; Paulino, Carl B; Slover, James D; Zuckerman, Joseph D; Egol, Kenneth A

2018-04-04

The number of periprosthetic proximal femoral fractures is expected to increase with the increasing prevalence of hip arthroplasties. While native hip fractures have a well-known association with mortality, there are currently limited data on this outcome among the subset of patients with periprosthetic proximal femoral fractures. Using the New York Statewide Planning and Research Cooperative System, we identified patients from 60 to 99 years old who were admitted to a hospital in the state with a periprosthetic proximal femoral fracture (n = 1,655) or a native hip (femoral neck or intertrochanteric) fracture (n = 97,231) between 2006 and 2014. Within the periprosthetic fracture cohort, the indication for the existing implant was not available in the data set. We used mixed-effects regression models to compare mortality at 1 and 6 months and 1 year for periprosthetic compared with native hip fractures. The risk of mortality for patients who sustained a periprosthetic proximal femoral fracture was no different from that for patients who sustained a native hip fracture at 1 month after injury (3.2% versus 4.6%; odds ratio [OR], 0.90; 95% confidence interval [CI], 0.68 to 1.19; p = 0.446), but was lower at 6 months (3.8% versus 6.5%; OR, 0.74; 95% CI, 0.57 to 0.95; p = 0.020) and 1 year (9.7% versus 15.9%; OR, 0.71; 95% CI, 0.60 to 0.85; p accounting for age and comorbidities. Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Assessment of fracture risk

International Nuclear Information System (INIS)

Kanis, John A.; Johansson, Helena; Oden, Anders; McCloskey, Eugene V.

2009-01-01

Fractures are a common complication of osteoporosis. Although osteoporosis is defined by bone mineral density at the femoral neck, other sites and validated techniques can be used for fracture prediction. Several clinical risk factors contribute to fracture risk independently of BMD. These include age, prior fragility fracture, smoking, excess alcohol, family history of hip fracture, rheumatoid arthritis and the use of oral glucocorticoids. These risk factors in conjunction with BMD can be integrated to provide estimates of fracture probability using the FRAX tool. Fracture probability rather than BMD alone can be used to fashion strategies for the assessment and treatment of osteoporosis.

The radiation swelling effect on fracture properties and fracture mechanisms of irradiated austenitic steels. Part I. Ductility and fracture toughness

Energy Technology Data Exchange (ETDEWEB)

Margolin, B., E-mail: mail@crism.ru; Sorokin, A.; Shvetsova, V.; Minkin, A.; Potapova, V.; Smirnov, V.

2016-11-15

The radiation swelling effect on the fracture properties of irradiated austenitic steels under static loading has been studied and analyzed from the mechanical and physical viewpoints. Experimental data on the stress-strain curves, fracture strain, fracture toughness and fracture mechanisms have been represented for austenitic steel of 18Cr-10Ni-Ti grade (Russian analog of AISI 321 steel) irradiated up to neutron dose of 150 dpa with various swelling. Some phenomena in mechanical behaviour of irradiated austenitic steels have been revealed and explained as follows: a sharp decrease of fracture toughness with swelling growth; untypical large increase of fracture toughness with decrease of the test temperature; some increase of fracture toughness after preliminary cyclic loading. Role of channel deformation and channel fracture has been clarified in the properties of irradiated austenitic steel and different tendencies to channel deformation have been shown and explained for the same austenitic steel irradiated at different temperatures and neutron doses.

Sensitivity Analysis of the Bone Fracture Risk Model

Science.gov (United States)

Lewandowski, Beth; Myers, Jerry; Sibonga, Jean Diane

2017-01-01

Introduction: The probability of bone fracture during and after spaceflight is quantified to aid in mission planning, to determine required astronaut fitness standards and training requirements and to inform countermeasure research and design. Probability is quantified with a probabilistic modeling approach where distributions of model parameter values, instead of single deterministic values, capture the parameter variability within the astronaut population and fracture predictions are probability distributions with a mean value and an associated uncertainty. Because of this uncertainty, the model in its current state cannot discern an effect of countermeasures on fracture probability, for example between use and non-use of bisphosphonates or between spaceflight exercise performed with the Advanced Resistive Exercise Device (ARED) or on devices prior to installation of ARED on the International Space Station. This is thought to be due to the inability to measure key contributors to bone strength, for example, geometry and volumetric distributions of bone mass, with areal bone mineral density (BMD) measurement techniques. To further the applicability of model, we performed a parameter sensitivity study aimed at identifying those parameter uncertainties that most effect the model forecasts in order to determine what areas of the model needed enhancements for reducing uncertainty. Methods: The bone fracture risk model (BFxRM), originally published in (Nelson et al) is a probabilistic model that can assess the risk of astronaut bone fracture. This is accomplished by utilizing biomechanical models to assess the applied loads; utilizing models of spaceflight BMD loss in at-risk skeletal locations; quantifying bone strength through a relationship between areal BMD and bone failure load; and relating fracture risk index (FRI), the ratio of applied load to bone strength, to fracture probability. There are many factors associated with these calculations including

Linking Advanced Visualization and MATLAB for the Analysis of 3D Gene Expression Data

Energy Technology Data Exchange (ETDEWEB)

Ruebel, Oliver; Keranen, Soile V.E.; Biggin, Mark; Knowles, David W.; Weber, Gunther H.; Hagen, Hans; Hamann, Bernd; Bethel, E. Wes

2011-03-30

Three-dimensional gene expression PointCloud data generated by the Berkeley Drosophila Transcription Network Project (BDTNP) provides quantitative information about the spatial and temporal expression of genes in early Drosophila embryos at cellular resolution. The BDTNP team visualizes and analyzes Point-Cloud data using the software application PointCloudXplore (PCX). To maximize the impact of novel, complex data sets, such as PointClouds, the data needs to be accessible to biologists and comprehensible to developers of analysis functions. We address this challenge by linking PCX and Matlab via a dedicated interface, thereby providing biologists seamless access to advanced data analysis functions and giving bioinformatics researchers the opportunity to integrate their analysis directly into the visualization application. To demonstrate the usefulness of this approach, we computationally model parts of the expression pattern of the gene even skipped using a genetic algorithm implemented in Matlab and integrated into PCX via our Matlab interface.

External fixation for closed pediatric femoral shaft fractures: where are we now?

Science.gov (United States)

Kong, Heather; Sabharwal, Sanjeev

2014-12-01

Recent advances in external fixation technique and pin design have sought to minimize complications such as pin site infection and premature removal of the external fixator. Although newer forms of internal fixation have gained popularity, external fixation may still have a role in managing pediatric femoral shaft fractures. We sought to assess the time to healing, limb alignment, and complications observed in a cohort of pediatric patients with closed femoral shaft fractures who were treated with external fixation. Over a 15-year period, one surgeon treated 289 pediatric patients with femur fractures, 31 (11%) of whom received an external fixator. The general indications for use of an external fixator during the period in question included length-unstable fractures, metadiaphyseal location, refracture, and pathologic fracture. Six patients (19%) had inadequate followup data and four patients (13%) were treated with a combination of flexible intramedullary nails and external fixation, leaving 21 patients for analysis. Mean age at injury was 10 years (range, 6-15 years) and followup averaged 22 months (range, 5-45 months) after removal of the fixator. Radiographs were examined for alignment and limb length discrepancy. Complications were recorded from a chart review. Mean time in the fixator was 17 weeks (range, 9-24 weeks). One patient sustained a refracture and one patient with an isolated femur fracture had a leg length discrepancy > 2 cm. There were no pin site infections requiring intravenous antibiotics or additional surgery. One patient with Blount disease and previous tibial osteotomy developed transient peroneal nerve palsy. Despite improvements in pin design and predictable fracture healing, complications such as refracture and leg length discrepancy after external fixation of pediatric femoral shaft fractures can occur. However, external fixation remains a viable alternative for certain fractures such as length-unstable fractures, metadiaphyseal

Monitoring Hydraulic Fracturing Using Ground-Based Controlled Source Electromagnetics

Science.gov (United States)

Hickey, M. S.; Trevino, S., III; Everett, M. E.

2017-12-01

Hydraulic fracturing allows hydrocarbon production in low permeability formations. Imaging the distribution of fluid used to create a hydraulic fracture can aid in the characterization of fracture properties such as extent of plume penetration as well as fracture azimuth and symmetry. This could contribute to improving the efficiency of an operation, for example, in helping to determine ideal well spacing or the need to refracture a zone. A ground-based controlled-source electromagnetics (CSEM) technique is ideal for imaging the fluid due to the change in field caused by the difference in the conductive properties of the fluid when compared to the background. With advances in high signal to noise recording equipment, coupled with a high-power, broadband transmitter we can show hydraulic fracture extent and azimuth with minimal processing. A 3D finite element code is used to model the complete well casing along with the layered subsurface. This forward model is used to optimize the survey design and isolate the band of frequencies with the best response. In the field, the results of the modeling are also used to create a custom pseudorandom numeric (PRN) code to control the frequencies transmitted through a grounded dipole source. The receivers record the surface voltage across two grounded dipoles, one parallel and one perpendicular to the transmitter. The data are presented as the displays of amplitude ratios across several frequencies with the associated spatial information. In this presentation, we show multiple field results in multiple basins in the United States along with the CSEM theory used to create the survey designs.

Simulation of counter-current imbibition in water-wet fractured reservoirs based on discrete-fracture model

Directory of Open Access Journals (Sweden)

Wang Yueying

2017-08-01

Full Text Available Isolated fractures usually exist in fractured media systems, where the capillary pressure in the fracture is lower than that of the matrix, causing the discrepancy in oil recoveries between fractured and non-fractured porous media. Experiments, analytical solutions and conventional simulation methods based on the continuum model approach are incompetent or insufficient in describing media containing isolated fractures. In this paper, the simulation of the counter-current imbibition in fractured media is based on the discrete-fracture model (DFM. The interlocking or arrangement of matrix and fracture system within the model resembles the traditional discrete fracture network model and the hybrid-mixed-finite-element method is employed to solve the associated equations. The Behbahani experimental data validates our simulation solution for consistency. The simulation results of the fractured media show that the isolated-fractures affect the imbibition in the matrix block. Moreover, the isolated fracture parameters such as fracture length and fracture location influence the trend of the recovery curves. Thus, the counter-current imbibition behavior of media with isolated fractures can be predicted using this method based on the discrete-fracture model.

Fracture characteristics in Japanese rock

International Nuclear Information System (INIS)

Ijiri, Yuji; Sawada, Atsushi; Akahori, Kuniaki

1999-11-01

It is crucial for the performance assessment of geosphere to evaluate the characteristics of fractures that can be dominant radionuclide migration pathways from a repository to biosphere. This report summarizes the characteristics of fractures obtained from broad literature surveys and the fields surveys at the Kamaishi mine in northern Japan and at outcrops and galleries throughout the country. The characteristics of fractures described in this report are fracture orientation, fracture shape, fracture frequency, fracture distribution in space, transmissivity of fracture, fracture aperture, fracture fillings, alteration halo along fracture, flow-wetted surface area in fracture, and the correlation among these characteristics. Since granitic rock is considered the archetype fractured media, a large amount of fracture data is available in literature. In addition, granitic rock has been treated as a potential host rock in many overseas programs, and has JNC performed a number of field observations and experiments in granodiorite at the Kamaishi mine. Therefore, the characteristics of fractures in granitic rock are qualitatively and quantitatively clarified to some extent in this report, while the characteristics of fractures in another rock types are not clarified. (author)

The link between the use of advanced planning and scheduling (APS) modules and factory context

DEFF Research Database (Denmark)

Kristensen, Jesper; Asmussen, Jesper Normann; Wæhrens, Brian Vejrum

2017-01-01

at factories characterized by low planning maturity, but lower for factories with medium planning maturity. For low planning maturity, the APS module is used for improving the configuration of the manufacturing system, whereas high planning maturity is required to capture performance benefits from optimization......Through a study of four embedded action research cases within a global OEM, it is investigated how the frequency of use and contribution of an Advanced Planning and Scheduling (APS) module are affected by factory context. The performance contribution of the APS module is found to be high...... and scenario planning. Further, it is found that planning complexity at the factory increases both the frequency of use and the contribution of using APS modules. On the basis of the findings, three propositions are formulated on the link between factory context and the use of APS module....

Cough-induced rib fractures.

Science.gov (United States)

Hanak, Viktor; Hartman, Thomas E; Ryu, Jay H

2005-07-01

To define the demographic, clinical, and radiological features of patients with cough-induced rib fractures and to assess potential risk factors. For this retrospective, single-center study, we identified all cases of cough-induced rib fractures diagnosed at the Mayo Clinic in Rochester, Minn, over a 9-year period between January 1, 1996, and January 31, 2005. Bone densitometry data from patients' medical records were analyzed, and T scores were used to classify patients into bone density categories. The mean +/- SD age of the 54 study patients at presentation was 55+/-17 years, and 42 patients (78%) were female. Patients presented with chest wall pain after onset of cough. Rib fracture was associated with chronic cough (> or =3 weeks' duration) in 85% of patients. Rib fractures were documented by chest radiography, rib radiography, computed tomography, or bone scan. Chest radiography had been performed in 52 patients and revealed rib fracture in 30 (58%). There were 112 fractured ribs in 54 patients. One half of patients had more than one fractured rib. Right-sided rib fractures alone were present in 17 patients (26 fractured ribs), left-sided in 23 patients (35 fractured ribs), and bilateral in 14 patients (51 fractured ribs). The most commonly fractured rib on both sides was rib 6. The fractures were most common at the lateral aspect of the rib cage. Bone densitometry was done in 26 patients and revealed osteopenia or osteoporosis in 17 (65%). Cough-induced rib fractures occur primarily in women with chronic cough. Middle ribs along the lateral aspect of the rib cage are affected most commonly. Although reduced bone density is likely a risk factor, cough-induced rib fractures can occur in the presence of normal bone density.

Influence of perforation erosion on multiple growing hydraulic fractures in multi-stage fracturing

Directory of Open Access Journals (Sweden)

Yongming Li

2018-02-01

Full Text Available In multi-stage hydraulic fracturing, the limited-entry method is widely used to promote uniform growth of multiple fractures. However, this method's effectiveness may be lost because the perforations will be eroded gradually during the fracturing period. In order to study the influence of perforation erosion on multiple growing hydraulic fractures, we combined the solid–fluid coupled model of hydraulic fracture growth with an empirical model of perforation erosion to implement numerical simulation. The simulations show clearly that the erosion of perforation will significantly deteriorate the non-uniform growth of multiple fractures. Based on the numerical model, we also studied the influences of proppant concentration and injection rates on perforation erosion in multi-stage hydraulic fracturing. The results indicate that the initial erosion rates become higher with the rising proppant concentration, but the growth of multiple hydraulic fractures is not sensitive to the varied proppant concentration. In addition, higher injection rates are beneficial significantly to the limited-entry design, leading to more uniform growth of fractures. Thus, in multi-stage hydraulic fracturing enough high injection rates are proposed to keep uniform growths. Keywords: Unconventional oil and gas reservoir, Horizontal well, Perforation friction, Perforation erosion, Multi-stage hydraulic fracturing, Numerical simulation, Mathematic model, Uniform growth of fractures

Association of Insulin-like Growth Factor-1, Bone Mass and Inflammation to Low-energy Distal Radius Fractures and Fracture Healing in Elderly Women Attending Emergency Care.

Science.gov (United States)

Chisalita, Simona I; Chong, Lee Ti; Wajda, Maciej; Adolfsson, Lars; Woisetschläger, Mischa; Spångeus, Anna

2017-11-01

Elderly patients suffer fractures through low-energy mechanisms. The distal radius is the most frequent fracture localization. Insulin-like growth factor-1 (IGF1) plays an important role in the maintenance of bone mass and its levels decline with advancing age and in states of malnutrition. Our aim was to investigate the association of IGF1 levels, bone mass, nutritional status, and inflammation to low-energy distal radius fractures and also study if fracture healing is influenced by IGF1, nutritional status, and inflammation. Postmenopausal women, 55 years or older, with low-energy distal radius fractures occurring due to falling on slippery ground, indoors or outdoors, were recruited in the emergency department (ED) and followed 1 and 5 weeks after the initial trauma with biomarkers for nutritional status and inflammation. Fractures were diagnosed according to standard procedure by physical examination and X-ray. All patients were conservatively treated with plaster casts in the ED. Patients who needed interventions were excluded from our study. Fracture healing was evaluated from radiographs. Fracture healing assessment was made with a five-point scale where the radiological assessment included callus formation, fracture line, and stage of union. Blood samples were taken within 24 h after fracture and analyzed in the routine laboratory. Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry (DXA). Thirty-eight Caucasian women, aged 70.5 ± 8.9 years (mean ± SD) old, were recruited. Nutritional status, as evaluated by albumin (40.3 ± 3.1 g/L), IGF1 (125.3 ± 39.9 μg/L), body mass index (26.9 ± 3.6 kg/m 2 ), arm diameter (28.9 ± 8.9 cm), and arm skinfold (2.5 ± 0.7 cm), was normal. A positive correlation was found between IGF1 at visit 1 and the lowest BMD for hip, spine, or radius (r = 0.39, P = 0.04). High sensitive C-reactive protein (hsCRP) and leukocytes were higher at the fracture event compared to 5 weeks later (P = 0.07 and P

Characteristic fracture spacing in primary and secondary recovery for naturally fractured reservoirs

NARCIS (Netherlands)

Gong, J.; Rossen, W.R.

2018-01-01

If the aperture distribution is broad enough in a naturally fractured reservoir, even one where the fracture network is highly inter-connected, most fractures can be eliminated without significantly affecting the flow through the fracture network. During a waterflood or enhanced-oil-recovery

Three dimensional fracture aperture and porosity distribution using computerized tomography

Science.gov (United States)

Wenning, Q.; Madonna, C.; Joss, L.; Pini, R.

2017-12-01

A wide range of geologic processes and geo-engineered applications are governed by coupled hydromechanical properties in the subsurface. In geothermal energy reservoirs, quantifying the rate of heat transfer is directly linked with the transport properties of fractures, underscoring the importance of fracture aperture characterization for achieving optimal heat production. In this context, coupled core-flooding experiments with non-invasive imaging techniques (e.g., X-Ray Computed Tomography - X-Ray CT) provide a powerful method to make observations of these properties under representative geologic conditions. This study focuses on quantifying fracture aperture distribution in a fractured westerly granite core by using a recently developed calibration-free method [Huo et al., 2016]. Porosity is also estimated with the X-ray saturation technique using helium and krypton gases as saturating fluids, chosen for their high transmissibility and high CT contrast [e.g., Vega et al., 2014]. The westerly granite sample (diameter: 5 cm, length: 10 cm) with a single through-going rough-walled fracture was mounted in a high-pressure aluminum core-holder and placed inside a medical CT scanner for imaging. During scanning the pore fluid pressure was undrained and constant, and the confining pressure was regulated to have the desired effective pressure (0.5, 5, 7 and 10 MPa) under loading and unloading conditions. 3D reconstructions of the sample have been prepared in terms of fracture aperture and porosity at a maximum resolution of (0.24×0.24×1) mm3. Fracture aperture maps obtained independently using helium and krypton for the whole core depict a similar heterogeneous aperture field, which is also dependent on confining pressure. Estimates of the average hydraulic aperture from CT scans are in quantitative agreement with results from fluid flow experiments. However, the latter lack of the level of observational detail achieved through imaging, which further evidence the

Fracture mechanical materials characterisation

International Nuclear Information System (INIS)

Wallin, K.; Planman, T.; Nevalainen, M.

1998-01-01

The experimental fracture mechanics development has been focused on the determination of reliable lower-bound fracture toughness estimates from small and miniature specimens, in particular considering the statistical aspects and loading rate effects of fracture mechanical material properties. Additionally, materials aspects in fracture assessment of surface cracks, with emphasis on the transferability of fracture toughness data to structures with surface flaws have been investigated. Further a modified crack-arrest fracture toughness test method, to increase the effectiveness of testing, has been developed. (orig.)

Fracture Mechanics

CERN Document Server

Zehnder, Alan T

2012-01-01

Fracture mechanics is a vast and growing field. This book develops the basic elements needed for both fracture research and engineering practice. The emphasis is on continuum mechanics models for energy flows and crack-tip stress- and deformation fields in elastic and elastic-plastic materials. In addition to a brief discussion of computational fracture methods, the text includes practical sections on fracture criteria, fracture toughness testing, and methods for measuring stress intensity factors and energy release rates. Class-tested at Cornell, this book is designed for students, researchers and practitioners interested in understanding and contributing to a diverse and vital field of knowledge. Alan Zehnder joined the faculty at Cornell University in 1988. Since then he has served in a number of leadership roles including Chair of the Department of Theoretical and Applied Mechanics, and Director of the Sibley School of Mechanical and Aerospace Engineering.  He teaches applied mechanics and his research t...

Fractures and fracture infillings of the Eye-Dashwa Lakes pluton, Atikokan, Ontario

International Nuclear Information System (INIS)

Stone, Denver; Kamineni, D.C.

1982-01-01

Fractures in the Eye-Dashwa pluton near Atikokan, Ontario can be subdivided on the basis of their filling materials. These materials include aplite, epidote, chlorite, and gypsum-carbonate-clay, listed in order of decreasing age established from crosscutting relations. Textues indicate that infilling occurred during fracture growth. Continuous cooling of the pluton during fracturing is inferred from the expected crystallization temperatures of fillings. Fracturing began before the pluton was completely solidified (650-600 0 C) and continued to temperatures below 100 0 C. Many fractures appear to have been sealed by the filling materials after initiation but were subsequently sheared and filled by lower temperatue materials. Apparently the majority of fractures formed during or immediately after pluton solidification and new fractures became smaller and more restricted in location as cooling progressed. Fractures and filling materials are seen as important features in assessing the possibility of movement of radionuclides in aqueous solutions away from a nuclear fuel waste repository

Breakage of cephalomedullary nailing in operative treatment of trochanteric and subtrochanteric femoral fractures.

Science.gov (United States)

von Rüden, Christian; Hungerer, Sven; Augat, Peter; Trapp, Oliver; Bühren, Volker; Hierholzer, Christian

2015-02-01

Mechanical breakage of cephalomedullary nail osteosynthesis is a rare complication attributed to delayed fracture union or nonunion. This study presents a series of cases of breakage and secondary lag screw dislocation after cephalomedullary nailing. The aim of this study was to identify factors that contribute to cephalomedullary nail breakage. In a retrospective case series review between 02/2005 and 12/2013, we analyzed 453 patients with trochanteric and subtrochanteric fracture who had been treated by cephalomedullary nailing. Fractures were classified according to AO/OTA classification. 13 patients with cephalomedullary nail breakage were included (failure rate 2.9 %). Seven patients were women, and six men with a mean age of 72 years (range 35-94). Implant breakage occurred 6 months postoperatively (range 1-19 months). In ten cases, breakage was secondary to delayed or nonunion, which was thought to be mainly due to insufficient reduction of the fracture, and in two cases due to loss of the lag screw because of missing set screw. In one case, breakage was apparent during elective metal removal following complete fracture healing. Short-term outcome was evaluated 6 months after operative revision using Harris hip score in 11 out of 13 patients showing a mean score of 84 %. Complete radiological fracture healing has been found in 11 patients available for follow-up within 6 months after revision surgery. Breakage of cephalomedullary nail osteosynthesis of trochanteric fractures is a severe complication. The results of our study demonstrate that revision surgery provides good clinical and radiological short-term results. Predominately, failures of trochanteric fractures are related to lack of surgeon performance. Therefore, application of the implant requires accurate preoperative planning, advanced surgical experience to evaluate the patient and the fracture classification, and precise surgical technique including attention to detail and anatomical

Computed tomograms of blowout fracture

International Nuclear Information System (INIS)

Ito, Haruhide; Hayashi, Minoru; Shoin, Katsuo; Hwang, Wen-Zern; Yamamoto, Shinjiro; Yonemura, Taizo.

1985-01-01

We studied 18 cases of orbital fractures, excluding optic canal fracture. There were 11 cases of pure blowout fracture and 3 of the impure type. The other 4 cases were orbital fractures without blowout fracture. The cardinal syndromes were diplopia, enophthalmos, and sensory disturbances of the trigeminal nerve in the pure type of blowout fracture. Many cases of the impure type of blowout fracture or of orbital fracture showed black eyes or a swelling of the eyelids which masked enophthalmos. Axial and coronal CT scans demonstrated: 1) the orbital fracture, 2) the degree of enophthalmos, 3) intraorbital soft tissue, such as incarcerated or prolapsed ocular muscles, 4) intraorbital hemorrhage, 5) the anatomical relation of the orbital fracture to the lacrimal canal, the trochlea, and the trigeminal nerve, and 6) the lesions of the paranasal sinus and the intracranial cavity. CT scans play an important role in determining what surgical procedures might best be employed. Pure blowout fractures were classified by CT scans into these four types: 1) incarcerating linear fracture, 2) trapdoor fracture, 3) punched-out fracture, and 4) broad fracture. Cases with severe head injury should be examined to see whether or not blowout fracture is present. If the patients are to hope to return to society, a blowout fracture should be treated as soon as possible. (author)

Computed tomograms of blowout fracture

Energy Technology Data Exchange (ETDEWEB)

Ito, Haruhide; Hayashi, Minoru; Shoin, Katsuo; Hwang, Wen-Zern; Yamamoto, Shinjiro; Yonemura, Taizo

1985-02-01

We studied 18 cases of orbital fractures, excluding optic canal fracture. There were 11 cases of pure blowout fracture and 3 of the impure type. The other 4 cases were orbital fractures without blowout fracture. The cardinal syndromes were diplopia, enophthalmos, and sensory disturbances of the trigeminal nerve in the pure type of blowout fracture. Many cases of the impure type of blowout fracture or of orbital fracture showed black eyes or a swelling of the eyelids which masked enophthalmos. Axial and coronal CT scans demonstrated: 1) the orbital fracture, 2) the degree of enophthalmos, 3) intraorbital soft tissue, such as incarcerated or prolapsed ocular muscles, 4) intraorbital hemorrhage, 5) the anatomical relation of the orbital fracture to the lacrimal canal, the trochlea, and the trigeminal nerve, and 6) the lesions of the paranasal sinus and the intracranial cavity. CT scans play an important role in determining what surgical procedures might best be employed. Pure blowout fractures were classified by CT scans into these four types: 1) incarcerating linear fracture, 2) trapdoor fracture, 3) punched-out fracture, and 4) broad fracture. Cases with severe head injury should be examined to see whether or not blowout fracture is present. If the patients are to hope to return to society, a blowout fracture should be treated as soon as possible. (author).

Facial Fractures.

Science.gov (United States)

Ricketts, Sophie; Gill, Hameet S; Fialkov, Jeffery A; Matic, Damir B; Antonyshyn, Oleh M

2016-02-01

After reading this article, the participant should be able to: 1. Demonstrate an understanding of some of the changes in aspects of facial fracture management. 2. Assess a patient presenting with facial fractures. 3. Understand indications and timing of surgery. 4. Recognize exposures of the craniomaxillofacial skeleton. 5. Identify methods for repair of typical facial fracture patterns. 6. Discuss the common complications seen with facial fractures. Restoration of the facial skeleton and associated soft tissues after trauma involves accurate clinical and radiologic assessment to effectively plan a management approach for these injuries. When surgical intervention is necessary, timing, exposure, sequencing, and execution of repair are all integral to achieving the best long-term outcomes for these patients.

Network worlds : from link analysis to virtual places.

Energy Technology Data Exchange (ETDEWEB)

Joslyn, C. (Cliff)

2002-01-01

Significant progress is being made in knowledge systems through recent advances in the science of very large networks. Attention is now turning in many quarters to the potential impact on counter-terrorism methods. After reviewing some of these advances, we will discuss the difference between such 'network analytic' approaches, which focus on large, homogeneous graph strucures, and what we are calling 'link analytic' approaches, which focus on somewhat smaller graphs with heterogeneous link types. We use this venue to begin the process of rigorously defining link analysis methods, especially the concept of chaining of views of multidimensional databases. We conclude with some speculation on potential connections to virtual world architectures.

Fracture Propagation and Permeability Change under Poro-thermoelastic Loads & Silica Reactivity in Enhanced Geothermal Systems

Energy Technology Data Exchange (ETDEWEB)

Ahmad Ghassemi

2009-10-01

Geothermal energy is recovered by circulating water through heat exchange areas within a hot rock mass. Geothermal reservoir rock masses generally consist of igneous and metamorphic rocks that have low matrix permeability. Therefore, cracks and fractures play a significant role in extraction of geothermal energy by providing the major pathways for fluid flow and heat exchange. Therefore, knowledge of the conditions leading to formation of fractures and fracture networks is of paramount importance. Furthermore, in the absence of natural fractures or adequate connectivity, artificial fractures are created in the reservoir using hydraulic fracturing. Multiple fractures are preferred because of the large size necessary when using only a single fracture. Although the basic idea is rather simple, hydraulic fracturing is a complex process involving interactions of high pressure fluid injections with a stressed hot rock mass, mechanical interaction of induced fractures with existing natural fractures, and the spatial and temporal variations of in-situ stress. As a result, it is necessary to develop tools that can be used to study these interactions as an integral part of a comprehensive approach to geothermal reservoir development, particularly enhanced geothermal systems. In response to this need we have developed advanced poro-thermo-chemo-mechanical fracture models for rock fracture research in support of EGS design. The fracture propagation models are based on a regular displacement discontinuity formulation. The fracture propagation studies include modeling interaction of induced fractures. In addition to the fracture propagation studies, two-dimensional solution algorithms have been developed and used to estimate the impact of pro-thermo-chemical processes on fracture permeability and reservoir pressure. Fracture permeability variation is studied using a coupled thermo-chemical model with quartz reaction kinetics. The model is applied to study quartz precipitation

Microstructural design in quenched and partitioned (Q&P) steels to improve their fracture properties

International Nuclear Information System (INIS)

Diego-Calderón, I. de; Sabirov, I.; Molina-Aldareguia, J.M.; Föjer, C.; Thiessen, R.; Petrov, R.H.

2016-01-01

Quenching and partitioning (Q&P) is receiving increased attention as a novel heat treatment to produce advanced high strength steels (AHSSs) containing martensite/retained austenite mixtures, with desirable combination of strength, ductility and toughness. Despite the significant body of research on microstructure and mechanical properties of Q&P steels, there is still a significant lack of knowledge on the effect of complex microstructure on their mechanical performance. This work addresses the effect of microstructural architecture in multiphase Q&P steels on their fracture behavior at macro- and micro-scales. It is demonstrated that the RA volume fraction does not affect significantly the local fracture initiation toughness, whereas it can greatly improve the total crack growth resistance in Q&P steels. In addition, matrix conditions can play an important role in the fracture behavior of Q&P steels. Based on the analysis of the experimental results, a general recipe to tailor fracture properties of Q&P steels is proposed.

Porosity, permeability and 3D fracture network characterisation of dolomite reservoir rock samples.

Science.gov (United States)

Voorn, Maarten; Exner, Ulrike; Barnhoorn, Auke; Baud, Patrick; Reuschlé, Thierry

2015-03-01

With fractured rocks making up an important part of hydrocarbon reservoirs worldwide, detailed analysis of fractures and fracture networks is essential. However, common analyses on drill core and plug samples taken from such reservoirs (including hand specimen analysis, thin section analysis and laboratory porosity and permeability determination) however suffer from various problems, such as having a limited resolution, providing only 2D and no internal structure information, being destructive on the samples and/or not being representative for full fracture networks. In this paper, we therefore explore the use of an additional method - non-destructive 3D X-ray micro-Computed Tomography (μCT) - to obtain more information on such fractured samples. Seven plug-sized samples were selected from narrowly fractured rocks of the Hauptdolomit formation, taken from wellbores in the Vienna basin, Austria. These samples span a range of different fault rocks in a fault zone interpretation, from damage zone to fault core. We process the 3D μCT data in this study by a Hessian-based fracture filtering routine and can successfully extract porosity, fracture aperture, fracture density and fracture orientations - in bulk as well as locally. Additionally, thin sections made from selected plug samples provide 2D information with a much higher detail than the μCT data. Finally, gas- and water permeability measurements under confining pressure provide an important link (at least in order of magnitude) towards more realistic reservoir conditions. This study shows that 3D μCT can be applied efficiently on plug-sized samples of naturally fractured rocks, and that although there are limitations, several important parameters can be extracted. μCT can therefore be a useful addition to studies on such reservoir rocks, and provide valuable input for modelling and simulations. Also permeability experiments under confining pressure provide important additional insights. Combining these and

Human evolution and osteoporosis-related spinal fractures.

Directory of Open Access Journals (Sweden)

Meghan M Cotter

Full Text Available The field of evolutionary medicine examines the possibility that some diseases are the result of trade-offs made in human evolution. Spinal fractures are the most common osteoporosis-related fracture in humans, but are not observed in apes, even in cases of severe osteopenia. In humans, the development of osteoporosis is influenced by peak bone mass and strength in early adulthood as well as age-related bone loss. Here, we examine the structural differences in the vertebral bodies (the portion of the vertebra most commonly involved in osteoporosis-related fractures between humans and apes before age-related bone loss occurs. Vertebrae from young adult humans and chimpanzees, gorillas, orangutans, and gibbons (T8 vertebrae, n = 8-14 per species, male and female, humans: 20-40 years of age were examined to determine bone strength (using finite element models, bone morphology (external shape, and trabecular microarchitecture (micro-computed tomography. The vertebrae of young adult humans are not as strong as those from apes after accounting for body mass (p<0.01. Human vertebrae are larger in size (volume, cross-sectional area, height than in apes with a similar body mass. Young adult human vertebrae have significantly lower trabecular bone volume fraction (0.26±0.04 in humans and 0.37±0.07 in apes, mean ± SD, p<0.01 and thinner vertebral shells than apes (after accounting for body mass, p<0.01. Since human vertebrae are more porous and weaker than those in apes in young adulthood (after accounting for bone mass, even modest amounts of age-related bone loss may lead to vertebral fracture in humans, while in apes, larger amounts of bone loss would be required before a vertebral fracture becomes likely. We present arguments that differences in vertebral bone size and shape associated with reduced bone strength in humans is linked to evolutionary adaptations associated with bipedalism.

Mechanics of Hydraulic Fractures

Science.gov (United States)

Detournay, Emmanuel

2016-01-01

Hydraulic fractures represent a particular class of tensile fractures that propagate in solid media under pre-existing compressive stresses as a result of internal pressurization by an injected viscous fluid. The main application of engineered hydraulic fractures is the stimulation of oil and gas wells to increase production. Several physical processes affect the propagation of these fractures, including the flow of viscous fluid, creation of solid surfaces, and leak-off of fracturing fluid. The interplay and the competition between these processes lead to multiple length scales and timescales in the system, which reveal the shifting influence of the far-field stress, viscous dissipation, fracture energy, and leak-off as the fracture propagates.

Hip fractures in elderly people : Surgery or no surgery? A systematic review and meta-analysis

NARCIS (Netherlands)

van de Ree, C.L.P.; de Jongh, M.A.C.; Peeters, Charles M M; de Munter, Leonie; Roukema, Jan A; Gosens, Taco

2017-01-01

Iintroduction: Increasing numbers of patients with hip fractures also have advanced comorbidities. A majority are treated surgically. However, a significantly increasing percentage of medically unfit patients with unacceptably high risk of perioperative death are treated nonoperatively. Important

Prevalencia de fracturas faciales vinculadas con el deporte Prevalence of facial fractures linked to sports practice

Directory of Open Access Journals (Sweden)

José Manuel Díaz Fernández

2004-08-01

Full Text Available Se realizó una investigación descriptiva y transversal en 57 pacientes con fracturas faciales adquiridas durante la actividad deportiva, los cuales fueron atendidos en el Servicio de Cirugía Maxilofacial del Hospital Provincial "Saturnino Lora" de Santiago de Cuba, en el quinquenio 1992-1996. Este tipo de lesión representó el 6,2 % del total de tratadas en dicho período. En los atletas que jugaban con pelota y practicaban técnicas de combate hubo la mayor prevalencia de estas lesiones, fundamentalmente en los deportes de pelota, boxeo, baloncesto, karate y softbol. El impacto contra otro atleta fue el mecanismo de lesión más frecuente, sobre todo en los grupos de combate y juegos con pelota. Las fracturas de mandíbula dentoalveolares y cigomáticas resultaron ser los patrones de fracturas preponderantes. La conducta terapéutica en estos pacientes no difirió sustancialmente de la aplicada en aquellos con lesiones producidas por otras causas. La restricción de la actividad atlética osciló entre 9 y 15 semanas después del tratamiento inicial. En los atletas de alto rendimiento lesionados se impone establecer las estandarizaciones en su proceso rehabilitador para la toma de decisiones con respecto a su incorporación, tanto a la práctica como a la competencia, lo cual es fundamental en este sentido.A descriptive cross-sectional research study was made on 57 patients with facial fractures suffered during sporting activities. These patients had been seen by the Maxillofacial Surgery Service of "Saturnino Lara" provincial hospital in Santiago de Cuba from 1992 to 1996 and this type of lesions represented 6.2% of the fractures treated in this period of time. These lesions were more prevailing in athletes who mainly played ball sports, boxing, basketball, karate and softball. The collision with another sportsman was the most frequent injure mechanism fundamentally fight and ball sports. Dentoalveolar and zygomatic mandibular fractures

The association between physical activity and osteoporotic fractures: a review of the evidence and implications for future research.

Science.gov (United States)

Moayyeri, Alireza

2008-11-01

Physical activity helps maintain mobility, physical functioning, bone mineral density (BMD), muscle strength, balance and, therefore, may help prevent falls and fractures among the elderly. Meanwhile, it is theoretically possible that physical activity increases risk of fractures as it may increase risk of falls and has only a modest effect on BMD. This review aims to assess the potential causal association between physical activity and osteoporotic fractures from an epidemiological viewpoint. As the medical literature lacks direct evidence from randomized controlled trials (RCTs) with fracture end points, a meta-analysis of 13 prospective cohort studies with hip fracture end point is presented. The current evidence base regarding the link between exercise and fracture risk determinants (namely, falls, BMD, and bone quality) are also summarized. Moderate-to-vigorous physical activity is associated with a hip fracture risk reduction of 45% (95% CI, 31-56%) and 38% (95% CI, 31-44%), respectively, among men and women. Risk of falling is suggested to be generally reduced among physically active people with a potential increased risk in the most active and inactive people. Positive effects of physical activity on BMD and bone quality are of a questionable magnitude for reduction of fracture risk. The complexity of relationship between physical activity and osteoporotic fractures points out to the need for RCTs to be conducted with fractures as the primary end point.

The Fate of Colloidal Swarms in Fractures

Science.gov (United States)

Pyrak-Nolte, L. J.; Olander, M. K.

2009-12-01

In the next 10-20 years, nano- and micro-sensor engineering will advance to the stage where sensor swarms could be deployed in the subsurface to probe rock formations and the fluids contained in them. Sensor swarms are groups of nano- or micro- sensors that are maintained as a coherent group to enable either sensor-to-sensor communication and/or coherent transmission of information as a group. The ability to maintain a swarm of sensors depends on the complexity of the flow paths in the rock, on the size and shape of the sensors and on the chemical interaction among the sensors, fluids, and rock surfaces. In this study, we investigate the effect of fracture aperture and fluid currents on the formation, evolution and break-up of colloidal swarms under gravity. Transparent cubic samples (100 mm x 100 mm x 100 mm) containing synthetic fractures with uniform and non-uniform aperture distributions were used to quantify the effect of aperture on swarm formation, swarm velocity, and swarm geometry using optical imaging. A fracture with a uniform aperture distribution was fabricated from two polished rectangular prisms of acrylic. A fracture with a non-uniform aperture distribution was created with a polished rectangular acrylic prism and an acrylic replica of an induced fracture surface from a carbonate rock. A series of experiments were performed to determine how swarm movement and geometry are affected as the walls of the fracture are brought closer together from 50 mm to 1 mm. During the experiments, the fracture was fully saturated with water. We created the swarms using two different particle sizes in dilute suspension (~ 1.0% by mass) . The particles were 3 micron diameter fluorescent polymer beads and 25 micron diameter soda-lime glass beads. The swarm behavior was imaged using an optical fluorescent imaging system composed of a CCD camera illuminated by a 100 mW diode-pumped doubled YAG laser. A swam was created when approximately 0.01 g drop of the suspension was

Modeling climate effects on hip fracture rate by the multivariate GARCH model in Montreal region, Canada

Science.gov (United States)

Modarres, Reza; Ouarda, Taha B. M. J.; Vanasse, Alain; Orzanco, Maria Gabriela; Gosselin, Pierre

2014-07-01

Changes in extreme meteorological variables and the demographic shift towards an older population have made it important to investigate the association of climate variables and hip fracture by advanced methods in order to determine the climate variables that most affect hip fracture incidence. The nonlinear autoregressive moving average with exogenous variable-generalized autoregressive conditional heteroscedasticity (ARMA X-GARCH) and multivariate GARCH (MGARCH) time series approaches were applied to investigate the nonlinear association between hip fracture rate in female and male patients aged 40-74 and 75+ years and climate variables in the period of 1993-2004, in Montreal, Canada. The models describe 50-56 % of daily variation in hip fracture rate and identify snow depth, air temperature, day length and air pressure as the influencing variables on the time-varying mean and variance of the hip fracture rate. The conditional covariance between climate variables and hip fracture rate is increasing exponentially, showing that the effect of climate variables on hip fracture rate is most acute when rates are high and climate conditions are at their worst. In Montreal, climate variables, particularly snow depth and air temperature, appear to be important predictors of hip fracture incidence. The association of climate variables and hip fracture does not seem to change linearly with time, but increases exponentially under harsh climate conditions. The results of this study can be used to provide an adaptive climate-related public health program and ti guide allocation of services for avoiding hip fracture risk.

Reprint of: The impact of fragility fracture and approaches to osteoporosis risk assessment worldwide.

Science.gov (United States)

Curtis, Elizabeth M; Moon, Rebecca J; Harvey, Nicholas C; Cooper, Cyrus

2017-08-01

Osteoporosis constitutes a major public health problem, through its association with age-related fractures, particularly of the hip, vertebrae, distal forearm and humerus. Substantial geographic variation has been noted in the incidence of osteoporotic fractures worldwide, with Western populations (North America, Europe and Oceania), reporting increases in hip fracture throughout the second half of the 20th century, with a stabilisation or decline in the last two decades. In developing populations however, particularly in Asia, the rates of osteoporotic fracture appears to be increasing. The massive global burden consequent to osteoporosis means that fracture risk assessment should be a high priority amongst health measures considered by policy makers. The WHO operational definition of osteoporosis, based on a measurement of bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA), has been used globally since the mid-1990s. However, although this definition identifies those at greatest individual risk of fracture, in the population overall a greater total number of fractures occur in individuals with BMD values above threshold for osteoporosis diagnosis. A number of web-based tools to enable the inclusion of clinical risk factors, with or without BMD, in fracture prediction algorithms have been developed to improve the identification of individuals at high fracture risk, the most commonly used globally being FRAX ® . Access to DXA, osteoporosis risk assessment, case finding and treatment varies worldwide, but despite such advances studies indicate that a minority of men and women at high fracture risk receive treatment. Importantly, research is ongoing to demonstrate the clinical efficacy and cost-effectiveness of osteoporosis case finding and risk assessment strategies worldwide. The huge burden caused by osteoporosis related fractures to individuals, healthcare systems and societies should provide a clear impetus for the progression of such

Chemical Signatures of and Precursors to Fractures Using Fluid Inclusion Stratigraphy

Energy Technology Data Exchange (ETDEWEB)

Lorie M. Dilley

2011-03-30

Enhanced Geothermal Systems (EGS) are designed to recover heat from the subsurface by mechanically creating fractures in subsurface rocks. Open or recently closed fractures would be more susceptible to enhancing the permeability of the system. Identifying dense fracture areas as well as large open fractures from small fracture systems will assist in fracture stimulation site selection. Geothermal systems are constantly generating fractures (Moore, Morrow et al. 1987), and fluids and gases passing through rocks in these systems leave small fluid and gas samples trapped in healed microfractures. These fluid inclusions are faithful records of pore fluid chemistry. Fluid inclusions trapped in minerals as the fractures heal are characteristic of the fluids that formed them, and this signature can be seen in fluid inclusion gas analysis. This report presents the results of the project to determine fracture locations by the chemical signatures from gas analysis of fluid inclusions. With this project we hope to test our assumptions that gas chemistry can distinguish if the fractures are open and bearing production fluids or represent prior active fractures and whether there are chemical signs of open fracture systems in the wall rock above the fracture. Fluid Inclusion Stratigraphy (FIS) is a method developed for the geothermal industry which applies the mass quantification of fluid inclusion gas data from drill cuttings and applying known gas ratios and compositions to determine depth profiles of fluid barriers in a modern geothermal system (Dilley, 2009; Dilley et al., 2005; Norman et al., 2005). Identifying key gas signatures associated with fractures for isolating geothermal fluid production is the latest advancement in the application of FIS to geothermal systems (Dilley and Norman, 2005; Dilley and Norman, 2007). Our hypothesis is that peaks in FIS data are related to location of fractures. Previous work (DOE Grant DE-FG36-06GO16057) has indicated differences in the

Pathological fractures in children

Science.gov (United States)

De Mattos, C. B. R.; Binitie, O.; Dormans, J. P.

2012-01-01

Pathological fractures in children can occur as a result of a variety of conditions, ranging from metabolic diseases and infection to tumours. Fractures through benign and malignant bone tumours should be recognised and managed appropriately by the treating orthopaedic surgeon. The most common benign bone tumours that cause pathological fractures in children are unicameral bone cysts, aneurysmal bone cysts, non-ossifying fibromas and fibrous dysplasia. Although pathological fractures through a primary bone malignancy are rare, these should be recognised quickly in order to achieve better outcomes. A thorough history, physical examination and review of plain radiographs are crucial to determine the cause and guide treatment. In most benign cases the fracture will heal and the lesion can be addressed at the time of the fracture, or after the fracture is healed. A step-wise and multidisciplinary approach is necessary in caring for paediatric patients with malignancies. Pathological fractures do not have to be treated by amputation; these fractures can heal and limb salvage can be performed when indicated. PMID:23610658

The Reliability of Classifications of Proximal Femoral Fractures with 3-Dimensional Computed Tomography: The New Concept of Comprehensive Classification

Directory of Open Access Journals (Sweden)

Hiroaki Kijima

2014-01-01

Full Text Available The reliability of proximal femoral fracture classifications using 3DCT was evaluated, and a comprehensive “area classification” was developed. Eleven orthopedists (5–26 years from graduation classified 27 proximal femoral fractures at one hospital from June 2013 to July 2014 based on preoperative images. Various classifications were compared to “area classification.” In “area classification,” the proximal femur is divided into 4 areas with 3 boundary lines: Line-1 is the center of the neck, Line-2 is the border between the neck and the trochanteric zone, and Line-3 links the inferior borders of the greater and lesser trochanters. A fracture only in the first area was classified as a pure first area fracture; one in the first and second area was classified as a 1-2 type fracture. In the same way, fractures were classified as pure 2, 3-4, 1-2-3, and so on. “Area classification” reliability was highest when orthopedists with varying experience classified proximal femoral fractures using 3DCT. Other classifications cannot classify proximal femoral fractures if they exceed each classification’s particular zones. However, fractures that exceed the target zones are “dangerous” fractures. “Area classification” can classify such fractures, and it is therefore useful for selecting osteosynthesis methods.

Coupled Fracture and Flow in Shale in Hydraulic Fracturing

Science.gov (United States)

Carey, J. W.; Mori, H.; Viswanathan, H.

2014-12-01

Production of hydrocarbon from shale requires creation and maintenance of fracture permeability in an otherwise impermeable shale matrix. In this study, we use a combination of triaxial coreflood experiments and x-ray tomography characterization to investigate the fracture-permeability behavior of Utica shale at in situ reservoir conditions (25-50 oC and 35-120 bars). Initially impermeable shale core was placed between flat anvils (compression) or between split anvils (pure shear) and loaded until failure in the triaxial device. Permeability was monitored continuously during this process. Significant deformation (>1%) was required to generate a transmissive fracture system. Permeability generally peaked at the point of a distinct failure event and then dropped by a factor of 2-6 when the system returned to hydrostatic failure. Permeability was very small in compression experiments (fashion as pressure increased. We also observed that permeability decreased with increasing fluid flow rate indicating that flow did not follow Darcy's Law, possibly due to non-laminar flow conditions, and conformed to Forscheimer's law. The coupled deformation and flow behavior of Utica shale, particularly the large deformation required to initiate flow, indicates the probable importance of activation of existing fractures in hydraulic fracturing and that these fractures can have adequate permeability for the production of hydrocarbon.

FEFLOW finite element modeling of flow, mass and heat transport in porous and fractured media

CERN Document Server

Diersch, Hans-Jörg G

2013-01-01

Placing advanced theoretical and numerical methods in the hands of modeling practitioners and scientists, this book explores the FEFLOW system for solving flow, mass and heat transport processes in porous and fractured media. Offers applications and exercises.

The Genotype-Tissue Expression (GTEx Project: Linking Clinical Data with Molecular Analysis to Advance Personalized Medicine

Directory of Open Access Journals (Sweden)

Judy C. Keen

2015-02-01

Full Text Available Evaluation of how genetic mutations or variability can directly affect phenotypic outcomes, the development of disease, or determination of a tailored treatment protocol is fundamental to advancing personalized medicine. To understand how a genotype affects gene expression and specific phenotypic traits, as well as the correlative and causative associations between such, the Genotype-Tissue Expression (GTEx Project was initiated The GTEx collection of biospecimens and associated clinical data links extensive clinical data with genotype and gene expression data to provide a wealth of data and resources to study the underlying genetics of normal physiology. These data will help inform personalized medicine through the identification of normal variation that does not contribute to disease. Additionally, these data can lead to insights into how gene variation affects pharmacodynamics and individualized responses to therapy.

Fluid-driven fracture propagation in heterogeneous media: Probability distributions of fracture trajectories.

Science.gov (United States)

Santillán, David; Mosquera, Juan-Carlos; Cueto-Felgueroso, Luis

2017-11-01

Hydraulic fracture trajectories in rocks and other materials are highly affected by spatial heterogeneity in their mechanical properties. Understanding the complexity and structure of fluid-driven fractures and their deviation from the predictions of homogenized theories is a practical problem in engineering and geoscience. We conduct a Monte Carlo simulation study to characterize the influence of heterogeneous mechanical properties on the trajectories of hydraulic fractures propagating in elastic media. We generate a large number of random fields of mechanical properties and simulate pressure-driven fracture propagation using a phase-field model. We model the mechanical response of the material as that of an elastic isotropic material with heterogeneous Young modulus and Griffith energy release rate, assuming that fractures propagate in the toughness-dominated regime. Our study shows that the variance and the spatial covariance of the mechanical properties are controlling factors in the tortuousness of the fracture paths. We characterize the deviation of fracture paths from the homogenous case statistically, and conclude that the maximum deviation grows linearly with the distance from the injection point. Additionally, fracture path deviations seem to be normally distributed, suggesting that fracture propagation in the toughness-dominated regime may be described as a random walk.

Simulations of tensile failure in glassy polymers: effect of cross-link density

International Nuclear Information System (INIS)

Panico, M; Narayanan, S; Brinson, L C

2010-01-01

Molecular dynamics simulations are adopted to investigate the failure mechanisms of glassy polymers, particularly with respect to increasing density of cross-links. In our simulations thermosetting polymers, which are cross-linked, exhibit an embrittlement compared with uncross-linked thermoplastics in a similar fashion to several experimental investigations (Levita et al 1991 J. Mater. Sci. 26 2348; Sambasivam et al 1997 J. Appl. Polym. Sci. 65 1001; Iijima et al 1992 Eur. Polym. J. 28 573). We perform a detailed analysis of this phenomenon and propose an interpretation based on the predominance of chain scission process over disentanglement in thermosetting polymers. We also elucidate the brittle fracture response of the thermosetting polymers

Traumatic thoracolumbar spine fractures

NARCIS (Netherlands)

J. Siebenga (Jan)

2013-01-01

textabstractTraumatic spinal fractures have the lowest functional outcomes and the lowest rates of return to work after injury of all major organ systems.1 This thesis will cover traumatic thoracolumbar spine fractures and not osteoporotic spine fractures because of the difference in fracture

A Weakest-Link Approach for Fatigue Limit of 30CrNiMo8 Steels (Preprint)

Science.gov (United States)

2011-03-01

34Application of a Weakest-Link Concept to the Fatigue Limit of the Bearing Steel Sae 52100 in a Bainitic Condition," Fatigue and Fracture of...AFRL-RX-WP-TP-2011-4206 A WEAKEST-LINK APPROACH FOR FATIGUE LIMIT OF 30CrNiMo8 STEELS (PREPRINT) S. Ekwaro-Osire and H.V. Kulkarni Texas...2011 4. TITLE AND SUBTITLE A WEAKEST-LINK APPROACH FOR FATIGUE LIMIT OF 30CrNiMo8 STEELS (PREPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT

Multi-Site Application of the Geomechanical Approach for Natural Fracture Exploration

Energy Technology Data Exchange (ETDEWEB)

R. L. Billingsley; V. Kuuskraa

2006-03-31

In order to predict the nature and distribution of natural fracturing, Advanced Resources Inc. (ARI) incorporated concepts of rock mechanics, geologic history, and local geology into a geomechanical approach for natural fracture prediction within mildly deformed, tight (low-permeability) gas reservoirs. Under the auspices of this project, ARI utilized and refined this approach in tight gas reservoir characterization and exploratory activities in three basins: the Piceance, Wind River and the Anadarko. The primary focus of this report is the knowledge gained on natural fractural prediction along with practical applications for enhancing gas recovery and commerciality. Of importance to tight formation gas production are two broad categories of natural fractures: (1) shear related natural fractures and (2) extensional (opening mode) natural fractures. While arising from different origins this natural fracture type differentiation based on morphology is sometimes inter related. Predicting fracture distribution successfully is largely a function of collecting and understanding the available relevant data in conjunction with a methodology appropriate to the fracture origin. Initially ARI envisioned the geomechanical approach to natural fracture prediction as the use of elastic rock mechanics methods to project the nature and distribution of natural fracturing within mildly deformed, tight (low permeability) gas reservoirs. Technical issues and inconsistencies during the project prompted re-evaluation of these initial assumptions. ARI's philosophy for the geomechanical tools was one of heuristic development through field site testing and iterative enhancements to make it a better tool. The technology and underlying concepts were refined considerably during the course of the project. As with any new tool, there was a substantial learning curve. Through a heuristic approach, addressing these discoveries with additional software and concepts resulted in a stronger set

The epidemic of hip fractures: are we on the right track?

Directory of Open Access Journals (Sweden)

Klaas A Hartholt

Full Text Available BACKGROUND: Hip fractures are a public health problem, leading to hospitalization, long-term rehabilitation, reduced quality of life, large healthcare expenses, and a high 1-year mortality. Especially older adults are at greater risk of fractures than the general population, due to the combination of an increased fall risk and osteoporosis. The aim of this study was to determine time trends in numbers and incidence rates of hip fracture-related hospitalizations and admission duration in the older Dutch population. METHODS AND FINDINGS: Secular trend analysis of all hospitalizations in the older Dutch population (≥65 years from 1981 throughout 2008, using the National Hospital Discharge Registry. Numbers, age-specific and age-adjusted incidence rates (per 10,000 persons of hospital admissions and hospital days due to a hip fracture were used as outcome measures in each year of the study. Between 1981 and 2008, the absolute number of hip fractures doubled in the older Dutch population. Incidence rates of hip fracture-related hospital admissions increased with age, and were higher in women than in men. The age-adjusted incidence rate increased from 52.0 to 67.6 per 10,000 older persons. However, since 1994 the incidence rate decreased (percentage annual change -0.5%, 95% CI: -0.7; -0.3, compared with the period 1981-1993 (percentage annual change 2.3%, 95% CI: 2.0; 2.7. The total number of hospital days was reduced by a fifth, due to a reduced admission duration in all age groups. A possible limitation was that data were obtained from a linked administrative database, which did not include information on medication use or co-morbidities. CONCLUSIONS: A trend break in the incidence rates of hip fracture-related hospitalizations was observed in the Netherlands around 1994, possibly as a first result of efforts to prevent falls and fractures. However, the true cause of the observation is unknown.

Epidemiology of rib fractures in older men: Osteoporotic Fractures in Men (MrOS) prospective cohort study.

Science.gov (United States)

Barrett-Connor, Elizabeth; Nielson, Carrie M; Orwoll, Eric; Bauer, Douglas C; Cauley, Jane A

2010-03-15

To study the causes and consequences of radiologically confirmed rib fractures (seldom considered in the context of osteoporosis) in community dwelling older men. Prospective cohort study (Osteoporotic Fractures in Men (MrOS) Study). 5995 men aged 65 or over recruited in 2000-2 from six US sites; 99% answered mailed questionnaires about falls and fractures every four months for a mean 6.2 (SD 1.3) year follow-up. New fractures validated by radiology reports; multivariate Cox proportional hazard ratios were used to evaluate factors independently associated with time to incident rib fracture; associations between baseline rib fracture and incident hip and wrist fracture were also evaluated. The incidence of rib fracture was 3.5/1000 person years, and 24% (126/522) of all incident non-spine fractures were rib fractures. Nearly half of new rib fractures (48%; n=61) followed falling from standing height or lower. Independent risk factors for an incident rib fracture were age 80 or above, low bone density, difficulty with instrumental activities of daily living, and a baseline history of rib/chest fracture. Men with a history of rib/chest fracture had at least a twofold increased risk of an incident rib fracture (adjusted hazard ratio 2.71, 95% confidence interval 1.86 to 3.95), hip fracture (2.05, 1.33 to 3.15), and wrist fracture (2.06, 1.14 to 3.70). Only 14/82 of men reported being treated with bone specific drugs after their incident rib fracture. Rib fracture, the most common incident clinical fracture in men, was associated with classic risk markers for osteoporosis, including old age, low hip bone mineral density, and history of fracture. A history of rib fracture predicted a more than twofold increased risk of future fracture of the rib, hip, or wrist, independent of bone density and other covariates. Rib fractures should be considered to be osteoporotic fractures in the evaluation of older men for treatment to prevent future fracture.

Analysis of fracture patterns and local stress field variations in fractured reservoirs

Science.gov (United States)

Deckert, Hagen; Drews, Michael; Fremgen, Dominik; Wellmann, J. Florian

2010-05-01

A meaningful qualitative evaluation of permeabilities in fractured reservoirs in geothermal or hydrocarbon industry requires the spatial description of the existing discontinuity pattern within the area of interest and an analysis how these fractures might behave under given stress fields. This combined information can then be used for better estimating preferred fluid pathway directions within the reservoir, which is of particular interest for defining potential drilling sites. A description of the spatial fracture pattern mainly includes the orientation of rock discontinuities, spacing relationships between single fractures and their lateral extent. We have examined and quantified fracture patterns in several outcrops of granite at the Costa Brava, Spain, and in the Black Forest, Germany, for describing reservoir characteristics. For our analysis of fracture patterns we have used photogrammetric methods to create high-resolution georeferenced digital 3D images of outcrop walls. The advantage of this approach, compared to conventional methods for fracture analysis, is that it provides a better 3D description of the fracture geometry as the entity of position, extent and orientation of single fractures with respect to their surrounding neighbors is conserved. Hence for instance, the method allows generating fracture density maps, which can be used for a better description of the spatial distribution of discontinuities in a given outcrop. Using photogrammetric techniques also has the advantage to acquire very large data sets providing statistically sound results. To assess whether the recorded discontinuities might act as fluid pathways information on the stress field is needed. A 3D model of the regional tectonic structure was created and the geometry of the faults was put into a mechanical 3D Boundary Element (BE) Model. The model takes into account the elastic material properties of the geological units and the orientation of single fault segments. The

On the possibility of magnetic nano-markers use for hydraulic fracturing in shale gas mining

Science.gov (United States)

Zawadzki, Jaroslaw; Bogacki, Jan

2016-04-01

Recently shale gas production became essential for the global economy, thanks to fast advances in shale fracturing technology. Shale gas extraction can be achieved by drilling techniques coupled with hydraulic fracturing. Further increasing of shale gas production is possible by improving the efficiency of hydraulic fracturing and assessing the spatial distribution of fractures in shale deposits. The latter can be achieved by adding magnetic markers to fracturing fluid or directly to proppant, which keeps the fracture pathways open. After that, the range of hydraulic fracturing can be assessed by measurement of vertical and horizontal component of earth's magnetic field before and after fracturing. The difference in these components caused by the presence of magnetic marker particles may allow to delineate spatial distribution of fractures. Due to the fact, that subterranean geological formations may contain minerals with significant magnetic properties, it is important to provide to the markers excellent magnetic properties which should be also, independent of harsh chemical and geological conditions. On the other hand it is of great significance to produce magnetic markers at an affordable price because of the large quantities of fracturing fluids or proppants used during shale fracturing. Examining the properties of nano-materials, it was found, that they possess clearly superior magnetic properties, as compared to the same structure but having a larger particle size. It should be then possible, to use lower amount of magnetic marker, to obtain the same effect. Although a research on properties of new magnetic nano-materials is very intensive, cheap magnetic nano-materials are not yet produced on a scale appropriate for shale gas mining. In this work we overview, in detail, geological, technological and economic aspects of using magnetic nano-markers in shale gas mining. Acknowledgment This work was supported by the NCBiR under Grant "Electromagnetic method to

Combined fracture of atlas and axis with infrequent

International Nuclear Information System (INIS)

Mosquera Betancourt, Dra. C. Gretel; Hernández González, MSc. Erick Héctor; Guevara Oré, Dr. Erick; Sulca Cedeño, Dr. Xavier; Téllez Isla, Dr. Rogers; Ramírez Reyes, Dra. Elizabet

2016-01-01

Background: combined lesions of atlas and axis are the most common cervical spine traumas in elderly people, with an incidence of about 70 %. The diagnosis demands the use of advance radiologic procedures and the treatment options runs through conservative to complex surgical interventions to restore the stability of the occipito-cervical region. Objective: to present a combined lesion of the first and second cervical vertebra as a less frequent shape of odontoid fracture. Clinical case: a 79-year-old patient who suffered a posterior cranial trauma followed by bilateral crevice brachialgia and paraesthesias after a horse fall. At physical exploration no signs of radicular or cordonal compression were demonstrated. Computarized axial tomography with tridimentional reconstructions showed a bilateral and symmetrical fracture of the posterior arch of the atlas, associated with longitudinal and oblique fracture of odontoid next to the isthmus. No dislocation was observed that is why the upper cervical spine stability was preserved. Conservative treatment was achieved by an external orthesis with a favourable evolution. Conclusions: for atlantoaxial traumatic lesions diagnosis, the use of computerized axial tomography is important associated or not with nuclear magnetic resonance. The stability of this region in correspondence with neurological status are the most important factors to select the best treatment choice. (author)

Radiological classification of mandibular fractures

International Nuclear Information System (INIS)

Mihailova, H.

2009-01-01

Mandibular fractures present the biggest part (up to 97%) of the facial bone fractures. Method of choice for diagnosing of mandibular fractures is conventional radiography. The aim of the issue is to present an unified radiological classification of mandibular fractures for the clinical practice. This classification includes only those clinical symptoms of mandibular fracture which could be radiologically objectified: exact anatomical localization (F1-F6), teeth in fracture line (Ta,Tb), grade of dislocation (D I, D II), occlusal disturbances (O(+), O(-)). Radiological symptoms expressed by letter and number symbols are systematized in a formula - FTDO of mandibular fractures similar to TNM formula for tumours. FTDO formula expresses radiological diagnose of each mandibular fracture but it doesn't include neither the site (left or right) of the fracture, nor the kind and number of fractures. In order to express topography and number of fractures the radiological formula is transformed into a decimal fraction. The symbols (FTD) of right mandible fracture are written in the numerator and those of the left site - in the denominator. For double and multiple fractures between the symbols for each fracture we put '+'. Symbols for occlusal disturbances are put down opposite, the fractional line. So topographo-anatomical formula (FTD/FTD)xO is formed. In this way the whole radiological information for unilateral, bilateral, single or multiple fractures of the mandible is expressed. The information in the radiological topography anatomic formula, resp. from the unified topography-anatomic classification ensures a quick and exact X-ray diagnose of mandibular fracture. In this way contributes to get better, make easier and faster X-ray diagnostic process concerning mandibular fractures. And all these is a precondition for prevention of retardation of the diagnosis mandibular fracture. (author)

Self-designed femoral neck guide pin locator for femoral neck fractures.

Science.gov (United States)

Xia, Shengli; Wang, Ziping; Wang, Minghui; Wu, Zuming; Wang, Xiuhui

2014-01-01

Closed reduction and fixation with 3 cannulated screws is a widely accepted surgery for the treatment of femoral neck fractures. However, how to obtain optimal screw placement remains unclear. In the current study, the authors designed a guide pin positioning system for femoral neck fracture cannulated screw fixation and examined its application value by comparing it with freehand guide needle positioning and with general guide pin locator positioning provided by equipment manufacturers. The screw reset rate, screw parallelism, triangle area formed by the link line of the entry point of 3 guide pins, and maximum vertical load bearing of the femoral neck after internal fixation were recorded. As expected, the triangle area was largest in the self-designed positioning group, followed by the general positioning group and the freehand positioning group. The difference among the 3 groups was statistically significant (P.05). The authors’ self-designed guide pin positioning system has the potential to accurately insert cannulated screws in femoral neck fractures and may reduce bone loss and unnecessary radiation.

An unusual stress fracture: Bilateral posterior longitudinal stress fracture of tibia.

Science.gov (United States)

Malkoc, Melih; Korkmaz, Ozgur; Ormeci, Tugrul; Oltulu, Ismail; Isyar, Mehmet; Mahirogulları, Mahir

2014-01-01

Stress fractures (SF) occur when healthy bone is subjected to cyclic loading, which the normal carrying range capacity is exceeded. Usually, stress fractures occur at the metatarsal bones, calcaneus, proximal or distal tibia and tends to be unilateral. This article presents a 58-year-old male patient with bilateral posterior longitudinal tibial stress fractures. A 58 years old male suffering for persistent left calf pain and decreased walking distance for last one month and after imaging studies posterior longitudinal tibial stress fracture was detected on his left tibia. After six months the patient was admitted to our clinic with the same type of complaints in his right leg. All imaging modalities and blood counts were performed and as a result longitudinal posterior tibial stress fractures were detected on his right tibia. Treatment of tibial stress fracture includes rest and modified activity, followed by a graded return to activity commensurate with bony healing. We have applied the same treatment protocol and our results were acceptable but our follow up time short for this reason our study is restricted for separate stress fractures of the posterior tibia. Although the main localization of tibial stress fractures were unilateral, anterior and transverse pattern, rarely, like in our case, the unusual bilateral posterior localization and longitudinal pattern can be seen. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Advances in crack-arrest technology for reactor pressure vessels

International Nuclear Information System (INIS)

Bass, B.R.; Pugh, C.E.

1988-01-01

The Heavy-Section Steel Technology (HSST) Program at the Oak Ridge National Laboratory (ORNL) under the sponsorship of the US Nuclear Regulatory Commission is continuing to improve the understanding of conditions that govern the initiation, rapid propagation, arrest, and ductile tearing of cracks in reactor pressure vessel (RPV) steels. This paper describes recent advances in a coordinated effort being conducted under the HSST Program by ORNL and several subcontracting groups to develop the crack-arrest data base and the analytical tools required to construct inelastic dynamic fracture models for RPV steels. Large-scale tests are being carried out to generate crack-arrest toughness data at temperatures approaching and above the onset of Charpy upper-shelf behavior. Small- and intermediate-size specimens subjected to static and dynamic loading are being developed and tested to provide additional fracture data for RPV steels. Viscoplastic effects are being included in dynamic fracture models and computer programs and their utility validated through analyses of data from carefully controlled experiments. Recent studies are described that examine convergence problems associated with energy-based fracture parameters in viscoplastic-dynamic fracture applications. Alternative techniques that have potential for achieving convergent solutions for fracture parameters in the context of viscoplastic-dynamic models are discussed. 46 refs., 15 figs., 3 tabs

Role of Alcohol on the Fracture Resistance of Dentin

Energy Technology Data Exchange (ETDEWEB)

Nalla, Ravi K.; Kinney, John H.; Tomsia, Antoni P.; Ritchie,Robert O.

2006-05-01

Healthy dentin, the mineralized tissue that makes up the bulk of the tooth, is naturally hydrated in vivo; however, it is known that various chemical reagents including acetone and ethanol can induce dehydration and thereby affect its properties. Here, we seek to investigate this in light of the effect alcohol can have on the mechanical properties of dentin, specifically by measuring the stiffness, strength and toughness of dentin in simulated body fluid and scotch whisky. Results indicate that chemical dehydration induced by the whisky has a significant beneficial effect on the elastic modulus, strength and fracture toughness of dentin. Although this makes teeth more resistant to fracture, the change in properties is fully reversible upon rehydration. This effect is considered to be associated with increased cross-linking of the collagen molecules from intermolecular hydrogen-bonding where water is replaced with weaker hydrogen-bond forming solvents such as alcohol.

Evaluation of Fibular Fracture Type vs Location of Tibial Fixation of Pilon Fractures.

Science.gov (United States)

Busel, Gennadiy A; Watson, J Tracy; Israel, Heidi

2017-06-01

Comminuted fibular fractures can occur with pilon fractures as a result of valgus stress. Transverse fibular fractures can occur with varus deformation. No definitive guide for determining the proper location of tibial fixation exists. The purpose of this study was to identify optimal plate location for fixation of pilon fractures based on the orientation of the fibular fracture. One hundred two patients with 103 pilon fractures were identified who were definitively treated at our institution from 2004 to 2013. Pilon fractures were classified using the AO/OTA classification and included 43-A through 43-C fractures. Inclusion criteria were age of at least 18 years, associated fibular fracture, and definitive tibial plating. Patients were grouped based on the fibular component fracture type (comminuted vs transverse), and the location of plate fixation (medial vs lateral) was noted. Radiographic outcomes were assessed for mechanical failures. Forty fractures were a result of varus force as evidenced by transverse fracture of the fibula and 63 were due to valgus force with a comminuted fibula. For the transverse fibula group, 14.3% mechanical complications were noted for medially placed plate vs 80% for lateral plating ( P = .006). For the comminuted fibular group, 36.4% of medially placed plates demonstrated mechanical complications vs 16.7% for laterally based plates ( P = .156). Time to weight bearing as tolerated was also noted to be significant between groups plated medially and laterally for the comminuted group ( P = .013). Correctly assessing the fibular component for pilon fractures provides valuable information regarding deforming forces. To limit mechanical complications, tibial plates should be applied in such a way as to resist the original deforming forces. Level of Evidence Level III, comparative study.

Fractures in multiple sclerosis

DEFF Research Database (Denmark)

Stenager, E; Jensen, K

1991-01-01

In a cross-sectional study of 299 MS patients 22 have had fractures and of these 17 after onset of MS. The fractures most frequently involved the femoral neck and trochanter (41%). Three patients had had more than one fracture. Only 1 patient had osteoporosis. The percentage of fractures increase...

Physical processes that control droplet transport in rock fracture systems

Science.gov (United States)

Hay, Katrina Moran

surface roughness; the relationship was found to exhibit a square root of time dependence. Rough surfaces also affect the movement of bulk fluid through the fractures. The speed of droplets moving downward between smooth and rough surfaces is seen to be significantly different. Experiments were used to develop predictive algorithms to calculate the speed of droplets in unsaturated rock fractures, which incorporate an adjusted contact angle for wet rough surfaces, and also incorporate the effect of dynamics on the evolution of the advancing contact angle. The third paper investigates the effect of intersection geometry on the larger scale distribution of fluid in a system of fractures. Fluid movement through fracture intersections depends on input flow parameters, geometry of the system, and capillary and gravitational forces. The physical mechanisms governing the process are analyzed to predict distribution of liquid into fracture branches and velocity of the output flow. This study will improve the ability to incorporate pore-scale fluid physics phenomena into large-scale models for predicting flow transport in rock fracture systems.

TIBIAL SHAFT FRACTURES.

Science.gov (United States)

Kojima, Kodi Edson; Ferreira, Ramon Venzon

2011-01-01

The long-bone fractures occur most frequently in the tibial shaft. Adequate treatment of such fractures avoids consolidation failure, skewed consolidation and reoperation. To classify these fractures, the AO/OTA classification method is still used, but it is worthwhile getting to know the Ellis classification method, which also includes assessment of soft-tissue injuries. There is often an association with compartmental syndrome, and early diagnosis can be achieved through evaluating clinical parameters and constant clinical monitoring. Once the diagnosis has been made, fasciotomy should be performed. It is always difficult to assess consolidation, but the RUST method may help in this. Radiography is assessed in two projections, and points are scored for the presence of the fracture line and a visible bone callus. Today, the dogma of six hours for cleaning the exposed fracture is under discussion. It is considered that an early start to intravenous antibiotic therapy and the lesion severity are very important. The question of early or late closure of the lesion in an exposed fracture has gone through several phases: sometimes early closure has been indicated and sometimes late closure. Currently, whenever possible, early closure of the lesion is recommended, since this diminishes the risk of infection. Milling of the canal when the intramedullary nail is introduced is still a controversial subject. Despite strong personal positions in favor of milling, studies have shown that there may be some advantage in relation to closed fractures, but not in exposed fractures.

Treatment of mandibular symphyseal fracture combined with dislocated intracapsular condylar fractures.

Science.gov (United States)

Xu, Xiaofeng; Shi, Jun; Xu, Bing; Dai, Jiewen; Zhang, Shilei

2015-03-01

To evaluate the treatment methods of mandibular symphyseal fracture combined with dislocated intracapsular condylar fractures (MSF&DICF) and to compare the effect of different treatment methods of condylar fractures. Twenty-eight patients with MSF&DICF were included in this study. Twenty-two sites were treated by open reduction, and all the medial condylar fragments were fixed with titanium screws; whereas the other 22 sites underwent close treatment. The surgical effect between these 2 groups was compared based on clinical examination and radiographic examination results. Seventeen of 22 condyle fractures were repositioned in the surgery group, whereas 4 of 22 condyle fractures were repositioned in the close treatment group. Statistical difference was observed between these 2 groups (P condyle fractures should be treated by surgical reduction with the maintenance of the attachment of lateral pterygoid muscle, which is beneficial to repositioning the dislocated condyle to its original physiological position, to closure of the mandibular lingual gap, to restore the mandibular width.

Classification of Porcine Cranial Fracture Patterns Using a Fracture Printing Interface,.

Science.gov (United States)

Wei, Feng; Bucak, Serhat Selçuk; Vollner, Jennifer M; Fenton, Todd W; Jain, Anil K; Haut, Roger C

2017-01-01

Distinguishing between accidental and abusive head trauma in children can be difficult, as there is a lack of baseline data for pediatric cranial fracture patterns. A porcine head model has recently been developed and utilized in a series of studies to investigate the effects of impact energy level, surface type, and constraint condition on cranial fracture patterns. In the current study, an automated pattern recognition method, or a fracture printing interface (FPI), was developed to classify cranial fracture patterns that were associated with different impact scenarios documented in previous experiments. The FPI accurately predicted the energy level when the impact surface type was rigid. Additionally, the FPI was exceedingly successful in determining fractures caused by skulls being dropped with a high-level energy (97% accuracy). The FPI, currently developed on the porcine data, may in the future be transformed to the task of cranial fracture pattern classification for human infant skulls. © 2016 American Academy of Forensic Sciences.

Multi-Attribute Seismic/Rock Physics Approach to Characterizing Fractured Reservoirs

Energy Technology Data Exchange (ETDEWEB)

Gary Mavko

2004-11-30

Most current seismic methods to seismically characterize fractures in tight reservoirs depend on a few anisotropic wave propagation signatures that can arise from aligned fractures. While seismic anisotropy can be a powerful fracture diagnostic, a number of situations can lessen its usefulness or introduce interpretation ambiguities. Fortunately, laboratory and theoretical work in rock physics indicates that a much broader spectrum of fracture seismic signatures can occur, including a decrease in P- and S-wave velocities, a change in Poisson's ratio, an increase in velocity dispersion and wave attenuation, as well as well as indirect images of structural features that can control fracture occurrence. The goal of this project was to demonstrate a practical interpretation and integration strategy for detecting and characterizing natural fractures in rocks. The approach was to exploit as many sources of information as possible, and to use the principles of rock physics as the link among seismic, geologic, and log data. Since no single seismic attribute is a reliable fracture indicator in all situations, the focus was to develop a quantitative scheme for integrating the diverse sources of information. The integrated study incorporated three key elements: The first element was establishing prior constraints on fracture occurrence, based on laboratory data, previous field observations, and geologic patterns of fracturing. The geologic aspects include analysis of the stratigraphic, structural, and tectonic environments of the field sites. Field observations and geomechanical analysis indicates that fractures tend to occur in the more brittle facies, for example, in tight sands and carbonates. In contrast, strain in shale is more likely to be accommodated by ductile flow. Hence, prior knowledge of bed thickness and facies architecture, calibrated to outcrops, are powerful constraints on the interpreted fracture distribution. Another important constraint is that

Hydrajet fracturing: an effective method for placing many fractures in openhole horizontal wells

Energy Technology Data Exchange (ETDEWEB)

Surjaatmadja, J. B.; Grundmann, S. R.; McDaniel, B.; Deeg, W. F. J.; Brumley, J. L.; Swor, L. C.

1998-12-31

A new method for openhole horizontal well fracturing that combines hydrajetting and fracturing techniques, which was developed on the basis of Bernoulli`s theorem, is described. This theorem has been effectively proven in many applications such as jet pumps, additive injection systems and jet aircraft engines. By using this method, operators can position a jetting tool, without the use of sealing elements, at the exact point where fracture is required. The method also permits the use of multiple fractures in the same well, which can be spaced evenly or unevenly as prescribed by the fracturing program. Damage can be avoided by placing hundreds of small fractures in a long horizontal section, or operators can use acid and/or propped sand techniques to place a combination of two fracture types in the well. The paper describes the basic principles of horizontal hydrajet fracturing, and elements of a laboratory model which was developed to demonstrate the effectiveness of the method.

Characterisation of hydraulically-active fractures in a fractured ...

African Journals Online (AJOL)

... in the initial stage of a site investigation to select the optimal site location or to evaluate the hydrogeological properties of fractures in underground exploration studies, such as those related geothermal reservoir evaluation and radioactive waste disposal. Keywords: self-potential method, hydraulically-conductive fractures, ...

Fracture propagation in sandstone and slate – Laboratory experiments, acoustic emissions and fracture mechanics

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Ferdinand Stoeckhert

2015-06-01

Full Text Available Fracturing of highly anisotropic rocks is a problem often encountered in the stimulation of unconventional hydrocarbon or geothermal reservoirs by hydraulic fracturing. Fracture propagation in isotropic material is well understood but strictly isotropic rocks are rarely found in nature. This study aims at the examination of fracture initiation and propagation processes in a highly anisotropic rock, specifically slate. We performed a series of tensile fracturing laboratory experiments under uniaxial as well as triaxial loading. Cubic specimens with edge lengths of 150 mm and a central borehole with a diameter of 13 mm were prepared from Fredeburg slate. An experiment using the rather isotropic Bebertal sandstone as a rather isotropic rock was also performed for comparison. Tensile fractures were generated using the sleeve fracturing technique, in which a polymer tube placed inside the borehole is pressurized to generate tensile fractures emanating from the borehole. In the uniaxial test series, the loading was varied in order to observe the transition from strength-dominated fracture propagation at low loading magnitudes to stress-dominated fracture propagation at high loading magnitudes.

Intertrochanteric fractures in elderly high risk patients treated with Ender nails and compression screw

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Gangadharan Sidhartha

2010-01-01

Full Text Available Background: Ender and Simon Weidner popularized the concept of closed condylocephlic nailing for intertrochanteric fractures in 1970. The clinical experience of authors revealed that Ender nailing alone cannot provide secure fixation in elderly patients with osteoporosis. Hence we conducted a study to evaluate the efficacy of a combined fixation procedure using Ender nails and a cannulated compression screw for intertrochanteric fractures. Materials and Methods: 76 patients with intertrochanteric fractures were treated using intramedullary Ender nails and cannulated compression screw from January 2004 to December 2007. The mean age of the patients was 80 years (range 70-105 years.Using the Evan′s system of classification 49 were stable and 27 unstable fractures. Inclusion criteria was high risk elderly patients (age > 70 years with intertrochanteric fracture. The exclusion criteria included patients with pressure sores over the trochanteric region. Many patients had pre-existing co-morbidities like diabetes mellitus, hypertension, COPD, ischemic heart disease, CVA and coronary artery bypass surgery. The two Ender nails of 4.5mm each were passed across the fracture site into the proximal neck. This was reinforced with a 6.5 mm cannulated compression screw passed from the sub trochanteric region, across the fracture into the head. Results: The mean follow-up was 14 months (range 9-19 months Average time to fracture union was 10 weeks (range 6-16 weeks. The mean knee ROM was 130o (± 5o. There was no case of nail penetration into hip joint. In five cases with advanced osteoporosis there was minimal migration of Ender nails distally. Conclusions: The Ender nailing combined with compression screw fixation in cases of intertrochanteric fractures in high risk elderly patients could achieve reliable fracture stability with minimal complications.

Rib Fractures

Science.gov (United States)

... Video) Achilles Tendon Tear Additional Content Medical News Rib Fractures By Thomas G. Weiser, MD, MPH, Associate Professor, ... Tamponade Hemothorax Injury to the Aorta Pulmonary Contusion Rib Fractures Tension Pneumothorax Traumatic Pneumothorax (See also Introduction to ...

Orbital fractures: a review

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Jeffrey M Joseph

2011-01-01

Full Text Available Jeffrey M Joseph, Ioannis P GlavasDivision of Ophthalmic Plastic and Reconstructive Surgery, Department of Ophthalmology, School of Medicine, New York University, New York, NY, USA; Manhattan Eye, Ear, and Throat Hospital, New York, NY, USAAbstract: This review of orbital fractures has three goals: 1 to understand the clinically relevant orbital anatomy with regard to periorbital trauma and orbital fractures, 2 to explain how to assess and examine a patient after periorbital trauma, and 3 to understand the medical and surgical management of orbital fractures. The article aims to summarize the evaluation and management of commonly encountered orbital fractures from the ophthalmologic perspective and to provide an overview for all practicing ophthalmologists and ophthalmologists in training.Keywords: orbit, trauma, fracture, orbital floor, medial wall, zygomatic, zygomatic complex, zmc fracture, zygomaticomaxillary complex fractures 

Orbital wall fractures

International Nuclear Information System (INIS)

Iinuma, Toshitaka; Ishio, Ken-ichirou; Yoshinami, Hiroyoshi; Kuriyama, Jun-ichi; Hirota, Yoshiharu.

1993-01-01

A total of 59 cases of mild facial fractures (simple orbital wall fractures, 34 cases, other facial fractures, 25 cases) with the clinical suspects of orbital wall fractures were evaluated both by conventional views (Waters' and Caldwell views) and coronal CT scans. Conventional views were obtained, as an average, after 4 days and CT after 7 days of injuries. Both the medial wall and the floor were evaluated at two sites, i.e., anterior and posterior. The ethmoid-maxillary plate was also included in the study. The degree of fractures was classified as, no fractures, fractures of discontinuity, dislocation and fragmentation. The coronal CT images in bone window condition was used as reference and the findings were compared between conventional views and CT. The correct diagnosis was obtained as follows: orbital floor (anterior, 78%, posterior, 73%), medial orbital wall (anterior, 72%, posterior, 72%) and ethmoid-maxillary plate (64%). The false positive diagnosis was as follows: orbital floor (anterior only, 13%), medial orbital wall (anterior only, 7%) and ethmoid-maxillary plate (11%). The false negative diagnosis was as follows: orbital floor (anterior, 9%, posterior, 10%), medial orbital wall (anterior, 21%, posterior, 28%) and ethmoid-maxillary plate (21%). The results were compared with those of others in the past. (author)

Multi-zone coupling productivity of horizontal well fracturing with complex fracture networks in shale gas reservoirs

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Weiyao Zhu

2018-02-01

Full Text Available In this paper, a series of specific studies were carried out to investigate the complex form of fracture networks and figure out the multi-scale flowing laws of nano/micro pores–complex fracture networks–wellbore during the development of shale reservoirs by means of horizontal well fracturing. First, hydraulic fractures were induced by means of Brazilian splitting tests. Second, the forms of the hydraulic fractures inside the rock samples were observed by means of X-ray CT scanning to measure the opening of hydraulic fractures. Third, based on the multi-scale unified flowing model, morphological description of fractures and gas flowing mechanism in the matrix–complex fracture network–wellbore, the productivity equation of single-stage horizontal well fracturing which includes diffusion, slipping and desorption was established. And fourthly, a productivity prediction model of horizontal well multi-stage fracturing in the shale reservoir was established considering the interference between the multi-stage fracturing zones and the pressure drop in the horizontal wellbore. The following results were obtained. First, hydraulic fractures are in the form of a complex network. Second, the measured opening of hydraulic fractures is in the range of 4.25–453 μm, averaging 112 μm. Third, shale gas flowing in different shapes of fracture networks follows different nonlinear flowing laws. Forth, as the fracture density in the strongly stimulated zones rises and the distribution range of the hydraulic fractures in strongly/weakly stimulated zones enlarges, gas production increases gradually. As the interference occurs in the flowing zones of fracture networks between fractured sections, the increasing amplitude of gas production rates decreases. Fifth, when the length of a simulated horizontal well is 1500 m and the half length of a fracture network in the strongly stimulated zone is 100 m, the productivity effect of stage 10 fracturing is the

Discrete fracture network for the Forsmark site

Energy Technology Data Exchange (ETDEWEB)

Darcel, C. [Itasca Consultants, Ecully (France); Davy, P.; Bour, O.; Dreuzy, J.R. de [Geosciences, Rennes (France)

2006-08-15

In this report, we aim at defining a self-consistent method for analyzing the fracture patterns from boreholes, outcrops and lineaments. The objective was both to point out some variations in the fracture network parameters, and to define the global scaling fracture models that can encompass all the constraints brought by the different datasets. Although a full description of the DFN model variability is obviously fundamental for the future, we have put emphasis on the determination of mean parameters. The main parameters of the disc-shaped DFN model are the fracture size, orientations and spatial density distribution. The scaling model is defined as an extrapolation of existing i) observations at specific scales and ii) local fitting models to the whole range of scales. The range of possible models is restricted to the power-law scaling models. During the project we have put emphasize on the definition of the theory and methodology necessary to assess a sound comparison between data taken at different scales, with different techniques. Both 'local' and 'global' models have been investigated. Local models are linked exactly to the dataset they represent. Then, the global DFN models arise from the association of local models, different scales and different sample support shapes. Discrepancies between local and global model illustrate the variability associated to the DFN models. We define two possible Global Scaling Models (GSM). The first one is consistent with the scaling measured in the outcrops (Model A). Its scaling exponent is a{sub 3d}=3.5 (eq. to k{sub r}=2.5); it overestimates the fracture densities observed in the lineament maps. The second one assumes that both lineaments and outcrops belong to the same distribution model (Model B), which entails a scaling exponent a{sub 3d}=3.9 (eq. to k{sub r}=2.9). Both models have been tested by looking for the best consistency in the fracture density-dip relationships, between boreholes data at

The role of strain localization in the fracture of irradiated pressure tube material

International Nuclear Information System (INIS)

Dutton, R.

1989-04-01

This report reviews those phenomena that lead to strain localization in zirconium alloys, with particular reference to the role played by the formation of shear bands in fracture processes. The important influence of plastic deformation, in general, on fracture mechanisms is emphasized. This is to be expected when elastic-plastic fracture mechanics is the chosen analytical technique. Intensely inhomogeneous characteristics of strain localization cause an abrupt bifurcation in the evolution of deformation strain and lead to plastic instability linked with intrinsic material behaviour (e.g., work softening) or of geometric origin (e.g., localized necking). Both of these effects are discussed in relation to measurable deformation parameters, such as the work hardening rate and strain rate sensitivity, which determine the degree of resistance to plastic instability. The modifying effect of irradiation on these quantities is given specific attention, the appropriate literature pertaining to Zircaloy and Zr-2.5% Nb being reviewed. Recommendations are made for a combined experimental and theoretical program to characterize strain localization and reduced ductility in irradiated cold-worked Zr-2.5% Nb pressure tube material. The relationship between the deformation properties and the fracture behaviour is discussed

Reduction of femoral fractures in long-term care facilities: the Bavarian fracture prevention study.

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Clemens Becker

Full Text Available BACKGROUND: Hip fractures are a major public health burden. In industrialized countries about 20% of all femoral fractures occur in care dependent persons living in nursing care and assisted living facilities. Preventive strategies for these groups are needed as the access to medical services differs from independent home dwelling older persons at risk of osteoporotic fractures. It was the objective of the study to evaluate the effect of a fall and fracture prevention program on the incidence of femoral fracture in nursing homes in Bavaria, Germany. METHODS: In a translational intervention study a fall prevention program was introduced in 256 nursing homes with 13,653 residents. The control group consisted of 893 nursing homes with 31,668 residents. The intervention consisted of staff education on fall and fracture prevention strategies, progressive strength and balance training, and on institutional advice on environmental adaptations. Incident femoral fractures served as outcome measure. RESULTS: In the years before the intervention risk of a femoral fracture did not differ between the intervention group (IG and control group (CG. During the one-year intervention period femoral fracture rates were 33.6 (IG and 41.0/1000 person years (CG, respectively. The adjusted relative risk of a femoral fracture was 0.82 (95% CI 0.72-0.93 in residents exposed to the fall and fracture prevention program compared to residents from CG. CONCLUSIONS: The state-wide dissemination of a multi-factorial fall and fracture prevention program was able to reduce femoral fractures in residents of nursing homes.

Advances in the management of orbital fractures.

Science.gov (United States)

Nguyen, P N; Sullivan, P

1992-01-01

Great progress has been made in both the basic science and the clinical knowledge base used in orbital reconstruction. With this, increasing complex orbital reconstructive problems are better managed. The diagnosis, treatment plan, and the actual reconstruction have evolved to a higher level. Several areas of progress are of note: the greater appreciation of the intimate relation between the bony orbit's shape and the position of the globe; application of computer technology in orbital injuries; effect of rigid fixation on autogenous and alloplastic graft; and the use of advanced biocompatible synthetic materials in orbital reconstruction. Although this progress has great impact on treatment of orbital injuries, there are many unanswered challenges in the treatment of the fragile frame of the window to the human soul.

Fracture mechanics

CERN Document Server

Perez, Nestor

2017-01-01

The second edition of this textbook includes a refined presentation of concepts in each chapter, additional examples; new problems and sections, such as conformal mapping and mechanical behavior of wood; while retaining all the features of the original book. The material included in this book is based upon the development of analytical and numerical procedures pertinent to particular fields of linear elastic fracture mechanics (LEFM) and plastic fracture mechanics (PFM), including mixed-mode-loading interaction. The mathematical approach undertaken herein is coupled with a brief review of several fracture theories available in cited references, along with many color images and figures. Dynamic fracture mechanics is included through the field of fatigue and Charpy impact testing. Explains computational and engineering approaches for solving crack-related problems using straightforward mathematics that facilitate comprehension of the physical meaning of crack growth processes; Expands computational understandin...

One-year mortality after hip fracture in older individuals: the effects of delirium and dementia.

Science.gov (United States)

Mitchell, Rebecca; Harvey, Lara; Brodaty, Henry; Draper, Brian; Close, Jacqueline

2017-09-01

Delirium is common in older hip fracture patients, yet its association with mortality after hip fracture remains uncertain. This study aimed to determine whether delirium was associated with all-cause one-year mortality after hip fracture in older patients and whether the effect of delirium was independent of dementia status. A retrospective analysis of linked hospitalisation and mortality data for patients aged ≥65 years with a hip fracture during 1 January 2010 to 30 June 2014 in New South Wales, Australia. The association between delirium and mortality after a hip fracture was assessed using Cox proportional hazard regression. There were 4,065 (14.6%) of 27,888 hip fracture hospitalisations identified with delirium during hospitalisation. Individuals with delirium had a higher age-adjusted rate of all-cause one-year mortality after hip fracture compared to individuals without delirium (35.3% versus 23.9%). After adjusting for covariates, the risk of all-cause mortality was increased at one-year post-admission for older individuals compared to those aged 65-69 years, for individuals with multiple comorbidities, dementia (Hazard Ratio (HR): 1.14; 95%CI:1.08-1.20), delirium (HR: 1.19; 95%CI:1.12-1.26), and who had an Intensive Care Unit admission (HR: 1.44; 95%CI:1.31-1.59). Comorbid delirium did not add additional mortality risk for individuals with a hip fracture who have dementia. Delirium identified in hospital was associated with all-cause one-year mortality after hip fracture in older Australians without dementia. As delirium is potentially preventable, better systematic assessment and documentation of a hip fracture patient's cognitive state is warranted to select the most effective strategies to prevent and manage delirium. Copyright © 2017 Elsevier B.V. All rights reserved.

Type 2 Diabetes and Risk of Hip Fractures and Non-Skeletal Fall Injuries in the Elderly: A Study From the Fractures and Fall Injuries in the Elderly Cohort (FRAILCO).

Science.gov (United States)

Wallander, Märit; Axelsson, Kristian F; Nilsson, Anna G; Lundh, Dan; Lorentzon, Mattias

2017-03-01

Questions remain about whether the increased risk of fractures in patients with type 2 diabetes (T2DM) is related mainly to increased risk of falling or to bone-specific properties. The primary aim of this study was to investigate the risk of hip fractures and non-skeletal fall injuries in older men and women with and without T2DM. We included 429,313 individuals (aged 80.8 ± 8.2 years [mean ± SD], 58% women) from the Swedish registry "Senior Alert" and linked the data to several nationwide registers. We identified 79,159 individuals with T2DM (45% with insulin [T2DM-I], 41% with oral antidiabetics [T2DM-O], and 14% with no antidiabetic treatment [T2DM-none]) and 343,603 individuals without diabetes. During a follow-up of approximately 670,000 person-years, we identified in total 36,132 fractures (15,572 hip fractures) and 20,019 non-skeletal fall injuries. In multivariable Cox regression models where the reference group was patients without diabetes and the outcome was hip fracture, T2DM-I was associated with increased risk (adjusted hazard ratio (HR) [95% CI] 1.24 [1.16-1.32]), T2DM-O with unaffected risk (1.03 [0.97-1.11]), and T2DM-none with reduced risk (0.88 [0.79-0.98]). Both the diagnosis of T2DM-I (1.22 [1.16-1.29]) and T2DM-O (1.12 [1.06-1.18]) but not T2DM-none (1.07 [0.98-1.16]) predicted non-skeletal fall injury. The same pattern was found regarding other fractures (any, upper arm, ankle, and major osteoporotic fracture) but not for wrist fracture. Subset analyses revealed that in men, the risk of hip fracture was only increased in those with T2DM-I, but in women, both the diagnosis of T2DM-O and T2DM-I were related to increased hip fracture risk. In conclusion, the risk of fractures differs substantially among patients with T2DM and an increased risk of hip fracture was primarily found in insulin-treated patients, whereas the risk of non-skeletal fall injury was consistently increased in T2DM with any diabetes medication. © 2016 American

Fracture and Healing of Rock Salt Related to Salt Caverns

International Nuclear Information System (INIS)

Chan, K.S.; Fossum, A.F.; Munson, D.E.

1999-01-01

In recent years, serious investigations of potential extension of the useful life of older caverns or of the use of abandoned caverns for waste disposal have been of interest to the technical community. All of the potential applications depend upon understanding the reamer in which older caverns and sealing systems can fail. Such an understanding will require a more detailed knowledge of the fracture of salt than has been necessary to date. Fortunately, the knowledge of the fracture and healing of salt has made significant advances in the last decade, and is in a position to yield meaningful insights to older cavern behavior. In particular, micromechanical mechanisms of fracture and the concept of a fracture mechanism map have been essential guides, as has the utilization of continuum damage mechanics. The Multimechanism Deformation Coupled Fracture (MDCF) model, which is summarized extensively in this work was developed specifically to treat both the creep and fracture of salt, and was later extended to incorporate the fracture healing process known to occur in rock salt. Fracture in salt is based on the formation and evolution of microfractures, which may take the form of wing tip cracks, either in the body or the boundary of the grain. This type of crack deforms under shear to produce a strain, and furthermore, the opening of the wing cracks produce volume strain or dilatancy. In the presence of a confining pressure, microcrack formation may be suppressed, as is often the case for triaxial compression tests or natural underground stress situations. However, if the confining pressure is insufficient to suppress fracture, then the fractures will evolve with time to give the characteristic tertiary creep response. Two first order kinetics processes, closure of cracks and healing of cracks, control the healing process. Significantly, volume strain produced by microfractures may lead to changes in the permeability of the salt, which can become a major concern in

Root fractures

DEFF Research Database (Denmark)

Andreasen, Jens Ove; Christensen, Søren Steno Ahrensburg; Tsilingaridis, Georgios

2012-01-01

The purpose of this study was to analyze tooth loss after root fractures and to assess the influence of the type of healing and the location of the root fracture. Furthermore, the actual cause of tooth loss was analyzed....

On the link between stress field and small-scale hydraulic fracture growth in anisotropic rock derived from microseismicity

Science.gov (United States)

Gischig, Valentin Samuel; Doetsch, Joseph; Maurer, Hansruedi; Krietsch, Hannes; Amann, Florian; Evans, Keith Frederick; Nejati, Morteza; Jalali, Mohammadreza; Valley, Benoît; Obermann, Anne Christine; Wiemer, Stefan; Giardini, Domenico

2018-01-01

To characterize the stress field at the Grimsel Test Site (GTS) underground rock laboratory, a series of hydrofracturing and overcoring tests were performed. Hydrofracturing was accompanied by seismic monitoring using a network of highly sensitive piezosensors and accelerometers that were able to record small seismic events associated with metre-sized fractures. Due to potential discrepancies between the hydrofracture orientation and stress field estimates from overcoring, it was essential to obtain high-precision hypocentre locations that reliably illuminate fracture growth. Absolute locations were improved using a transverse isotropic P-wave velocity model and by applying joint hypocentre determination that allowed for the computation of station corrections. We further exploited the high degree of waveform similarity of events by applying cluster analysis and relative relocation. Resulting clouds of absolute and relative located seismicity showed a consistent east-west strike and 70° dip for all hydrofractures. The fracture growth direction from microseismicity is consistent with the principal stress orientations from the overcoring stress tests, provided that an anisotropic elastic model for the rock mass is used in the data inversions. The σ1 stress is significantly larger than the other two principal stresses and has a reasonably well-defined orientation that is subparallel to the fracture plane; σ2 and σ3 are almost equal in magnitude and thus lie on a circle defined by the standard errors of the solutions. The poles of the microseismicity planes also lie on this circle towards the north. Analysis of P-wave polarizations suggested double-couple focal mechanisms with both thrust and normal faulting mechanisms present, whereas strike-slip and thrust mechanisms would be expected from the overcoring-derived stress solution. The reasons for these discrepancies can be explained by pressure leak-off, but possibly may also involve stress field rotation around the

Fracturing process and effect of fracturing degree on wave velocity of a crystalline rock

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Charalampos Saroglou

2017-10-01

Full Text Available The present paper investigates the effect of fracturing degree on P- and S-wave velocities in rock. The deformation of intact brittle rocks under loading conditions is characterized by a microcracking procedure, which occurs due to flaws in their microscopic structure and propagates through the intact rock, leading to shear fracture. This fracturing process is of fundamental significance as it affects the mechanical properties of the rock and hence the wave velocities. In order to determine the fracture mechanism and the effect of fracturing degree, samples were loaded at certain percentages of peak strength and ultrasonic wave velocity was recorded after every test. The fracturing degree was recorded on the outer surface of the sample and quantified by the use of the indices P10 (traces of joints/m, P20 (traces of joints/m2 and P21 (length of fractures/m2. It was concluded that the wave velocity decreases exponentially with increasing fracturing degree. Additionally, the fracturing degree is described adequately with the proposed indices. Finally, other parameters concerning the fracture characteristics, rock type and scale influence were found to contribute to the velocity decay and need to be investigated further.

Milk and yogurt consumption are linked with higher bone mineral density but not with hip fracture: the Framingham Offspring Study.

Science.gov (United States)

Sahni, Shivani; Tucker, Katherine L; Kiel, Douglas P; Quach, Lien; Casey, Virginia A; Hannan, Marian T

2013-01-01

Dairy foods are a complex source of essential nutrients. In this study, fluid dairy intake, specifically milk, and yogurt intakes were associated with hip but not spine bone mineral density (BMD), while cream may adversely influence BMD, suggesting that not all dairy products are equally beneficial for the skeleton. This study seeks to examine associations of milk, yogurt, cheese, cream, most dairy (total dairy without cream), and fluid dairy (milk + yogurt) with BMD at femoral neck (FN), trochanter (TR), and spine, and with incident hip fracture over 12-year follow-up in the Framingham Offspring Study. Three thousand two hundred twelve participants completed a food frequency questionnaire (1991–1995 or 1995–1998) and were followed for hip fracture until 2007 [corrected]. Two thousand five hundred and six participants had DXA BMD (1996-2001). Linear regression was used to estimate adjusted mean BMD while Cox-proportional hazards regression was used to estimate adjusted hazard ratios (HR) for hip fracture risk. Final models simultaneously included dairy foods adjusting for each other. Mean baseline age was 55 (±1.6) years, range 26-85. Most dairy intake was positively associated with hip and spine BMD. Intake of fluid dairy and milk was related with hip but not spine BMD. Yogurt intake was associated with TR-BMD alone. Cheese and cream intakes were not associated with BMD. In final models, yogurt intake remained positively associated with TR-BMD, while cream tended to be negatively associated with FN-BMD. Yogurt intake showed a weak protective trend for hip fracture [HR(95%CI), ≤4 serv/week, 0.46 (0.21-1.03) vs. >4 serv/week, 0.43 (0.06-3.27)]. No other dairy groups showed a significant association (HRs range, 0.53-1.47) with limited power (n, fractures = 43). Milk and yogurt intakes were associated with hip but not spine BMD, while cream may adversely influence BMD. Thus, not all dairy products are equally beneficial for the skeleton. Suggestive fracture

Tibial Plateau Fractures

DEFF Research Database (Denmark)

Elsøe, Rasmus

This PhD thesis reported an incidence of tibial plateau fractures of 10.3/100,000/year in a complete Danish regional population. The results reported that patients treated for a lateral tibial plateau fracture with bone tamp reduction and percutaneous screw fixation achieved a satisfactory level...... with only the subgroup Sport significantly below the age matched reference population. The thesis reports a level of health related quality of life (Eq5d) and disability (KOOS) significantly below established reference populations for patients with bicondylar tibial plateau fracture treated with a ring...... fixator, both during treatment and at 19 months following injury. In general, the thesis demonstrates that the treatment of tibial plateau fractures are challenging and that some disabilities following these fractures must be expected. Moreover, the need for further research in the area, both with regard...

Symptoms of anxiety or depression and risk of fracture in older people: the Hertfordshire Cohort Study.

Science.gov (United States)

Gale, Catharine R; Dennison, Elaine M; Edwards, Mark; Sayer, Avan Aihie; Cooper, Cyrus

2012-01-01

The aim of this study was to examine the prospective association between symptoms of anxiety and depression and risk of fracture in older people. Results showed that men, but not women, with probable anxiety at baseline had an increased risk of fracture. The use of psychotropic drugs has been linked with an increased risk of fracture in older people, but there are indications that the conditions for which these drugs were prescribed may themselves influence fracture risk. The aim of this study was to investigate the relation between symptoms of anxiety and depression and risk of fracture in older people. The study design is a prospective cohort study. One thousand eighty-seven men and 1,050 women aged 59-73 years completed the Hospital Anxiety and Depression Scale (HADS). Data on incident fracture during an average follow-up period of 5.6 years were collected through interview and a postal questionnaire. Compared to men with no or few symptoms of anxiety (score ≤7 on the HADS anxiety subscale), men with probable anxiety (score ≥11) had an increased risk of fracture: After adjustment for age and potential confounding factors, the odds ratio (OR) (95 % confidence interval) was 4.03 (1.55, 10.5). There were no associations between levels of anxiety and fracture risk in women. Few men or women had probable depression at baseline (score ≥11 on the HADS depression subscale). Amongst men with possible depression (score 8-10), there was an increased risk of fracture that was of borderline significance: multivariate-adjusted OR 3.57 (0.99, 12.9). There was no association between possible depression and fracture risk in women. High levels of anxiety in older men may increase their risk of fracture. Future research needs to replicate this finding in other populations and investigate the underlying mechanisms.

Leakage losses from a hydraulic fracture and fracture propagation

International Nuclear Information System (INIS)

Johnson, R.E.; Gustafson, C.W.

1988-01-01

The fluid mechanics of viscous fluid injection into a fracture embedded in a permeable rock formation is studied. Coupling between flow in the fracture and flow in the rock is retained. The analysis is based on a perturbation scheme that assumes the depth of penetration of the fluid into the rock is small compared to the characteristic length w 3 0 /k, where w 0 is the characteristic crack width and k is the permeability. This restriction, however, is shown to be minor. The spatial dependence of the leakage rate per unit length from the fracture is found to be linear, decreasing from the well bore to the fracture tip where it vanishes. The magnitude of the leakage rate per unit length is found to decay in time as t -1 /sup // 3 if the injection rate at the well bore is constant, and as t -1 /sup // 2 if the well bore pressure is held constant. The results cast considerable doubt on the validity of Carter's well-known leakage formula (Drilling Prod. Prac. API 1957, 261) derived from a one-dimensional theory. Using the simple fracture propagation model made popular by Carter, the present work also predicts that the fracture grows at a rate proportional to t 1 /sup // 3 for a fixed well bore injection rate and a rate proportional to t 1 /sup // 4 for a fixed well bore pressure

Realignment Surgery for Malunited Ankle Fracture.

Science.gov (United States)

Guo, Chang-Jun; Li, Xing-Cheng; Hu, Mu; Xu, Yang; Xu, Xiang-Yang

2017-02-01

To investigate the characteristics and the results of realignment surgery for the treatment of malunited ankle fracture. Thirty-three patients with malunited fractures of the ankle who underwent reconstructive surgery at our hospital from January 2010 to January 2014 were reviewed. The tibial anterior surface angle (TAS), the tibiotalar tilt angle (TTA), the malleolar angle (MA), and the tibial lateral surface angle (TLS) were measured. Clinical assessment was performed with use of the American Orthopaedic Foot and Ankle Society (AOFAS) scale and visual analogue scale (VAS) scores, and the osteoarthritis stage was determined radiographically with the modified Takakura classification system. The Wilcoxon matched-pairs test was used to analyze the difference between the preoperative and the postoperative data. The mean follow-up was 36 months (range, 20-60 months). The mean age at the time of realignment surgery was 37.1 years (range, 18-62 years). Compared with preoperation, the TAS at the last follow-up showed a significant increase (88.50° ± 4.47° vs. 90.80° ± 3.49°, P = 0.0035); similar results were observed in TTA (1.62° ± 1.66° vs. 0.83° ± 0.90°, P ankle osteoarthritis, and was treated by ankle joint distraction. Realignment surgery for a malunited ankle fracture can reduce pain, improve function, and delay ankle arthrodesis or total ankle replacement. Postoperative large talar tilt and advanced stages of ankle arthritis are the risk factors for the surgery. © 2017 Chinese Orthopaedic Association and John Wiley & Sons Australia, Ltd.

Training improves agreement among doctors using the Neer system for proximal humeral fractures in a systematic review

DEFF Research Database (Denmark)

Brorson, Stig; Hróbjartsson, Asbjørn

2008-01-01

OBJECTIVE: To systematically review studies of observer agreement among doctors classifying proximal humeral fractures according to the Neer system. STUDY DESIGN AND SETTING: A systematic review. We searched for observational studies in which doctors classified proximal humeral fractures according......, and the methodological quality was assessed. RESULTS: We included 11 observational studies (88 observers and 468 cases). Mean kappa-values for interobserver agreement ranged from 0.17 to 0.52. Agreement did not improve through selection of experienced observers, advanced imaging modalities, or simplification...

Spontaneous rib fractures.

Science.gov (United States)

Katrancioglu, Ozgur; Akkas, Yucel; Arslan, Sulhattin; Sahin, Ekber

2015-07-01

Other than trauma, rib fracture can occur spontaneously due to a severe cough or sneeze. In this study, patients with spontaneous rib fractures were analyzed according to age, sex, underlying pathology, treatment, and complications. Twelve patients who presented between February 2009 and February 2011 with spontaneous rib fracture were reviewed retrospectively. The patients' data were evaluated according to anamnesis, physical examination, and chest radiographs. The ages of the patients ranged from 34 to 77 years (mean 55.91 ± 12.20 years), and 7 (58.4%) were male. All patients had severe cough and chest pain. The fractures were most frequently between 4th and 9th ribs; multiple rib fractures were detected in 5 (41.7%) patients. Eight (66.7%) patients had chronic obstructive pulmonary disease, 2 (16.7%) had bronchial asthma, and 2 (16.7%) had osteoporosis. Bone densitometry revealed a high risk of bone fracture in all patients. Patients with chronic obstructive pulmonary disease or bronchial asthma had been treated with high-dose steroids for over a year. Spontaneous rib fracture due to severe cough may occur in patients with osteoporosis, chronic obstructive pulmonary disease, or bronchial asthma, receiving long-term steroid therapy. If these patients have severe chest pain, chest radiography should be performed to check for bone lesions. © The Author(s) 2015.

Cough-induced rib fractures.

Science.gov (United States)

Sano, Atsushi; Tashiro, Ken; Fukuda, Tsutomu

2015-10-01

Occasionally, patients who complain of chest pain after the onset of coughing are diagnosed with rib fractures. We investigated the characteristics of cough-induced rib fractures. Between April 2008 and December 2013, 17 patients were referred to our hospital with chest pain after the onset of coughing. Rib radiography was performed, focusing on the location of the chest pain. When the patient had other signs and symptoms such as fever or persistent cough, computed tomography of the chest was carried out. We analyzed the data retrospectively. Rib fractures were found in 14 of the 17 patients. The age of the patients ranged from 14 to 86 years (median 39.5 years). Ten patients were female and 4 were male. Three patients had chronic lung disease. There was a single rib fracture in 9 patients, and 5 had two or more fractures. The middle and lower ribs were the most commonly involved; the 10th rib was fractured most frequently. Cough-induced rib fractures occur in every age group regardless of the presence or absence of underlying disease. Since rib fractures often occur in the lower and middle ribs, rib radiography is useful for diagnosis. © The Author(s) 2015.

Identification of fracture zones and its application in automatic bone fracture reduction.

Science.gov (United States)

Paulano-Godino, Félix; Jiménez-Delgado, Juan J

2017-04-01

The preoperative planning of bone fractures using information from CT scans increases the probability of obtaining satisfactory results, since specialists are provided with additional information before surgery. The reduction of complex bone fractures requires solving a 3D puzzle in order to place each fragment into its correct position. Computer-assisted solutions may aid in this process by identifying the number of fragments and their location, by calculating the fracture zones or even by computing the correct position of each fragment. The main goal of this paper is the development of an automatic method to calculate contact zones between fragments and thus to ease the computation of bone fracture reduction. In this paper, an automatic method to calculate the contact zone between two bone fragments is presented. In a previous step, bone fragments are segmented and labelled from CT images and a point cloud is generated for each bone fragment. The calculated contact zones enable the automatic reduction of complex fractures. To that end, an automatic method to match bone fragments in complex fractures is also presented. The proposed method has been successfully applied in the calculation of the contact zone of 4 different bones from the ankle area. The calculated fracture zones enabled the reduction of all the tested cases using the presented matching algorithm. The performed tests show that the reduction of these fractures using the proposed methods leaded to a small overlapping between fragments. The presented method makes the application of puzzle-solving strategies easier, since it does not obtain the entire fracture zone but the contact area between each pair of fragments. Therefore, it is not necessary to find correspondences between fracture zones and fragments may be aligned two by two. The developed algorithms have been successfully applied in different fracture cases in the ankle area. The small overlapping error obtained in the performed tests

Fracture analysis

International Nuclear Information System (INIS)

Ueng, Tzoushin; Towse, D.

1991-01-01

Fractures are not only the weak planes of a rock mass, but also the easy passages for the fluid flow. Their spacing, orientation, and aperture will affect the deformability, strength, heat transmittal, and fluid transporting properties of the rock mass. To understand the thermomechanical and hydrological behaviors of the rock surrounding the heater emplacement borehole, the location, orientation, and aperture of the fractures of the rock mass should be known. Borehole television and borescope surveys were performed to map the location, orientation, and aperture of the fractures intersecting the boreholes drilled in the Prototype Engineered Barrier System Field Tests (PEBSFT) at G-Tunnel. Core logging was also performed during drilling. However, because the core was not oriented and the depth of the fracture cannot be accurately determined, the results of the core logging were only used as reference and will not be discussed here

Scaphoid fractures in children

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Gajdobranski Đorđe

2014-01-01

Full Text Available Introduction. Scaphoid fractures are rare in childhood. Diagnosis is very difficult to establish because carpal bones are not fully ossified. In suspected cases comparative or delayed radiography is used, as well as computerized tomography, magnetic resonance imaging, ultrasound and bone scintigraphy. Majority of scaphoid fractures are treated conservatively with good results. In case of delayed fracture healing various types of treatment are available. Objective. To determine the mechanism of injury, clinical healing process, types and outcome of treatment of scaphoid fractures in children. Methods. We retrospectively analyzed patients with traumatic closed fracture of the scaphoid bone over a ten-year period (2002-2011. The outcome of the treatment of “acute” scaphoid fracture was evaluated using the Mayo Wrist Score. Results. There were in total 34 patients, of mean age 13.8 years, with traumatic closed fracture of the scaphoid bone, whose bone growth was not finished yet. Most common injury mechanism was fall on outstretched arm - 76% of patients. During the examined period 31 children with “acute” fracture underwent conservative treatment, with average immobilization period of 51 days. Six patients were lost to follow-up. In the remaining 25 patients, after completed rehabilitation, functional results determined by the Mayo Wrist Score were excellent. Conclusion. Conservative therapy of “acute” scaphoid fractures is an acceptable treatment option for pediatric patients with excellent functional results.

Fluid driven fracture mechanics in highly anisotropic shale: a laboratory study with application to hydraulic fracturing

Science.gov (United States)

Gehne, Stephan; Benson, Philip; Koor, Nick; Enfield, Mark

2017-04-01

The finding of considerable volumes of hydrocarbon resources within tight sedimentary rock formations in the UK led to focused attention on the fundamental fracture properties of low permeability rock types and hydraulic fracturing. Despite much research in these fields, there remains a scarcity of available experimental data concerning the fracture mechanics of fluid driven fracturing and the fracture properties of anisotropic, low permeability rock types. In this study, hydraulic fracturing is simulated in a controlled laboratory environment to track fracture nucleation (location) and propagation (velocity) in space and time and assess how environmental factors and rock properties influence the fracture process and the developing fracture network. Here we report data on employing fluid overpressure to generate a permeable network of micro tensile fractures in a highly anisotropic shale ( 50% P-wave velocity anisotropy). Experiments are carried out in a triaxial deformation apparatus using cylindrical samples. The bedding planes are orientated either parallel or normal to the major principal stress direction (σ1). A newly developed technique, using a steel guide arrangement to direct pressurised fluid into a sealed section of an axially drilled conduit, allows the pore fluid to contact the rock directly and to initiate tensile fractures from the pre-defined zone inside the sample. Acoustic Emission location is used to record and map the nucleation and development of the micro-fracture network. Indirect tensile strength measurements at atmospheric pressure show a high tensile strength anisotropy ( 60%) of the shale. Depending on the relative bedding orientation within the stress field, we find that fluid induced fractures in the sample propagate in two of the three principal fracture orientations: Divider and Short-Transverse. The fracture progresses parallel to the bedding plane (Short-Transverse orientation) if the bedding plane is aligned (parallel) with the

Small specimen test results and application of advanced models for fracture mechanics assessment of RPV integrity; Ergebnisse von Kleinproben und Anwendung von Modellansaetzen zur bruchmechanischen Bewertung der RDB-Integritaet

Energy Technology Data Exchange (ETDEWEB)

Keim, Elisabeth; Huemmer, Matthias [AREVA NP GmbH (Germany); Hoffmann, Harald [VGB (Germany); Nagel, Gerhard [e-on Kernkraft (Germany); Kuester, Karin [VENE (Germany); Koenig, Guenter; Ilg, Ulf [EnBW (Germany); Widera, Martin [RWE (Germany); Rebsamen, Daniel [KKW Goesgen (Germany)

2008-07-01

For the RPV (reactor pressure vessel) integrity assessment the transferability of specimen test results to components is of main importance. The international project TIMES (transferability of fracture toughness of irradiated materials to components and structures) is focussed on the transferability of fracture mechanical characteristics of irradiated materials to components or structures, in order to allow the quantification of differences between sample and component characteristics based on experiments and calculations. The studies were performed for the brittle and brittle-ductile regions of the material characteristics using specimens from original RPV materials in different conditions. Based on case studies the consequence of a component assessment with postulated defects are shown when specimen-related materials properties are used. Since it is not possible to prove the transferability for an RPV in detail, component-similar effects were investigated that allow in combination with numerical modelling to quantify the safety margin. Samples and experimental procedures were developed that simulated the real component situation. The effects of crack depth and multiaxial loads, relevant for real components, were investigated with these samples. A micromechanical model was developed based on the weakest link theory and the statistical failure probability; this model is used for the prediction of fracture toughness of samples and components with defects. For a component with postulated defects the safety margin was assessed using different methodologies, based on standard fracture mechanical samples, taking into account component specific aspects. [German] Fuer die Bewertung der RDB-Integritaet ist die Uebertragbarkeit von Probenkennwerten auf Bauteile von grosser Bedeutung. Dazu wurde das Projekt ''TIMES'' - ein internationales Projekt zur Uebertragbarkeit von Bruchzaehigkeitskennwerten von bestrahlten Materialien auf Komponenten und Strukturen - durchgefuehrt, um

Radiological study of the mandibular fractures

Energy Technology Data Exchange (ETDEWEB)

Kim, Ju Won; Kim, Kyoung A; Koh, Kwang Jun [Department of Oral and Maxillofacial Radiology, School of Dentistry, and Institute of Oral Bio Science, Chonbuk National University, Jeonju (Korea, Republic of)

2009-06-15

To classify and evaluate mandibular fractures. The author classified mandibular fractures of 284 patients who were referred to the Chonbuk National University Dental Hospital during the period from March 2004 to June 2007. This study was based on the conventional radiographs as well as computed tomographs which were pertained to the 284 patients who have had the mandibular fractures including the facial bone fractures. And mandibular fractures were classified with respect to gender, age, site and type of the fractures. More frequently affected gender with mandibular fracture was male with the ratio of 3.3 : 1. The most frequently affected age with mandibular fracture was third decade (38%), followed by fourth decade (16%), second decade (15%), fifth decade (11%), sixth decade (7%), seventh decade (5%), eighth decade (4%), first decade (4%), and ninth decade (0.3%). The most frequent type of mandibular fracture was single fracture (58%), followed by double fracture (39%), triple fracture (3%). The most common site of mandibular fracture was mandibular condyle as 113 cases (27.7%) and the next was mandibular symphysis as 109 cases (26.7%), mandibular angle as 103 cases (25.3%), mandibular body as 83 cases (20.3%) in order. The sum of fracture sites were 408 sites and there were 1.4 fracture sites per one patient. The number of mandible fractures accompanied with facial bone fractures were 41 cases (14.4%). The results showed the most frequent type and common site of mandibular fracture was single fracture and mandibular condyle respectively.

Radiological study of the mandibular fractures

International Nuclear Information System (INIS)

Kim, Ju Won; Kim, Kyoung A; Koh, Kwang Jun

2009-01-01

To classify and evaluate mandibular fractures. The author classified mandibular fractures of 284 patients who were referred to the Chonbuk National University Dental Hospital during the period from March 2004 to June 2007. This study was based on the conventional radiographs as well as computed tomographs which were pertained to the 284 patients who have had the mandibular fractures including the facial bone fractures. And mandibular fractures were classified with respect to gender, age, site and type of the fractures. More frequently affected gender with mandibular fracture was male with the ratio of 3.3 : 1. The most frequently affected age with mandibular fracture was third decade (38%), followed by fourth decade (16%), second decade (15%), fifth decade (11%), sixth decade (7%), seventh decade (5%), eighth decade (4%), first decade (4%), and ninth decade (0.3%). The most frequent type of mandibular fracture was single fracture (58%), followed by double fracture (39%), triple fracture (3%). The most common site of mandibular fracture was mandibular condyle as 113 cases (27.7%) and the next was mandibular symphysis as 109 cases (26.7%), mandibular angle as 103 cases (25.3%), mandibular body as 83 cases (20.3%) in order. The sum of fracture sites were 408 sites and there were 1.4 fracture sites per one patient. The number of mandible fractures accompanied with facial bone fractures were 41 cases (14.4%). The results showed the most frequent type and common site of mandibular fracture was single fracture and mandibular condyle respectively.