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Cracks
Kinds of Cracks Terms modified by Cracks Selected AbstractsDEFINITIVE DIAGNOSIS OF EARLY ENAMEL AND DENTINAL CRACKS BASED ON MICROSCOPIC EVALUATIONJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 7 2003Joel H. Berg DDS [source] Crack,heroin speedball injection and its implications for vein care: qualitative studyADDICTION, Issue 11 2007Tim Rhodes ABSTRACT Background We report on an exploratory qualitative study investigating drug injectors' narratives of vein damage and groin (femoral vein) injection associated with the injection of crack,heroin speedball. Methods We undertook 44 in-depth qualitative interviews among injectors of crack,heroin speedball in Bristol and London, England, in 2006. Findings The data suggest an emerging culture of crack-based speedball injection. Injectors' narratives link speedball injection with shifts towards groin injection articulated as an acceptable risk, and not merely as a last resort in the face of increased vein deterioration associated with speedball. Accounts of vein damage linked to speedball emphasize ,missed hits' related to the local anaesthetic action of crack, the excess use of citric in the preparation of speedball injections and ,flushing' when making a hit. We find that groin injection persists despite an awareness of health risks and medical complications. Conclusions We emphasize an urgent need for reviewing harm reduction in relation to vein care in the context of shifts to crack-based speedball injection, and the use of the femoral vein, among UK injectors. There is an additional need for interventions to promote safer groin and speedball injecting as well as to prevent transitions toward groin and crack injection. [source] Crack,Tip Toughness of a Soft Lead Zirconate TitanateJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2003Alain B. Kounga Njiwa Crack,opening displacement (COD) measurements were performed on a commercial lead zirconate titanate (PZT). The intrinsic fracture toughness (or crack,tip toughness) of this material was determined using a new evaluation procedure, which takes into account the near,tip CODs and complete crack profile CODs. The crack,tip toughness KI0 was determined from an extrapolation of COD data obtained at various loading stages, thus avoiding the complications caused by subcritical crack growth in PZT. Results for plane strain and plane stress condition are presented. [source] Crack dancing in the United Kingdom: Apropos a video case presentationMOVEMENT DISORDERS, Issue 8 2007MRCP, Shankar Kamath MD Abstract We report an adult patient presenting with choreiform movements 4 days after a large intravenous dose of cocaine. These movements were transitory and they normalized a week after admission. We believe this to be the first video case of acute chorea secondary to cocaine,a phenomenon popularly known as "crack dancing. " Cocaine abuse is associated with a wide range of movement disorders, including dystonia and exacerbation of Tourette's syndrome, multifocal tics, opsoclonus-myoclonus, choreiform movements, and stereotyped behavior known as "punding." Transient choreiform movements with a typical duration of 2 to 6 days are recognized by cocaine abusers themselves as crack dancing, but are infrequently reported. We present a video report of a patient with cocaine dependency and choreiform movements that normalized within a week of admission. © 2007 Movement Disorder Society [source] A Finite Interface Crack Interacting With A Subinterface Crack In Metal/Piezoelectric Ceramic BimaterialPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2003Wen-Ye Tian The "pseudo-traction-electric-displacement' method was adopted to solve the interaction problem between a finite interface crack and a subinterface crack in metal/piezoelectric bimaterial. After deriving the fundamental solutions for a finite interface crack and a special subinterface crack respectively loaded by the normal and tangential concentrated tractions and the concentrated electric displacement, the present interaction problem was reduced to a system of integral equations, which may be solved numerically. The crack tip mode I stress intensity factor was calculated and detailed comparisons of the results derived under the compound mechanical-electric loading conditions and those derived under the purely mechanical loading condition are performed. [source] A Possibilistic Petri Net Model for Diagnosing Cracks in RC StructuresCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 6 2003Kevin F. R. Liu PPN integrates Petri nets with possibilistic reasoning and maintains the advantages of both formalisms. Two major features of PPN include the possibilistic token to carry information to describe an object and its corresponding possibility and necessity measures, and four types of possibilistic transitions,inference, duplication, aggregation, and aggregation-duplication. A reasoning algorithm, based on possibilistic Petri nets, is also developed to execute PPN. The PPN model and the reasoning algorithm are further used to diagnose possible causes of cracking in RC structures, and three basic cases are considered to demonstrate the applicability of the approach. The reliability of the results is increased by explaining the diagnostic process through the movement of tokens. Moreover, the confidence level associated with each possible cause of concrete cracking can be used to determine the relevance of the diagnosis. [source] Fallen between the Cracks: Conservation Linking Land and SeaCONSERVATION BIOLOGY, Issue 4 2007N. A. Sloan No abstract is available for this article. [source] Mechanical properties of single crystalline and glassy lithium triborateCRYSTAL RESEARCH AND TECHNOLOGY, Issue 4 2008I. P. Shakhverdova Abstract Mechanical properties of LiB3O5 single crystal plates with different orientation as well as of glass with the same composition have been investigated. The nano- (H) and microhardness (HM), the reduced Young's modulus (Er) and the crack behaviour of the samples were studied. Both hardness and Young's modulus of glass appeared smaller in comparison to corresponding single crystal data (H , 7 , 8 GPa, HM , 6 GPa, Er , 70 , 80 GPa for glass and H , 10 , 15 GPa, HM , 6 ,11 GPa, Er , 93 , 155 GPa for single crystal). H, Er, and the plane of crack propagation proved orientation-dependent. Cracks in the glass sample were not observed up to 0.49 N microindentation load, whereas for the single crystal the cracks appeared already at 0.098N. In single crystals the observed cleavage planes {211} and/or {412} are oriented nearly parallel to planes of B-O rings. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Computation of the J -integral for large strainsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 12 2008Ágnes Horváth Abstract The phenomenon of failure by catastrophic crack propagation in structural materials poses problems of design and analysis in many fields of engineering. Cracks are present to some degree in all structures. They may exist as basic defects in the constituent materials or they may be induced in construction or during service life. Using the finite element method, a lot of papers deal with the calculation of stress intensity factors for two- and three-dimensional geometries containing cracks of different shapes under various loadings to elastic bodies. In order to increase the accuracy of the results, special elements have been used. They are described together with methods for calculating the stress intensity factors from the computed results. At the vicinity of a crack tip, the strains are not always small, but they may also be large. In this case, the J -integral can also be applied to characterize the cracks in elastic or elastic,plastic bodies. This paper describes the computation of the two-dimensional J -integral for large strains to elastic and elastic,plastic bodies and represents some numerical examples. Copyright © 2007 John Wiley & Sons, Ltd. [source] Boundary element formulation for 3D transversely isotropic cracked bodiesINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 4 2004M. P. Ariza Abstract The boundary traction integral representation is obtained in elasticity when the classical displacement representation is differentiated and combined according to Hooke's law. The use of both traction and displacement integral representations leads to a mixed (or dual) formulation of the BEM where the discretization effort for crack problems is much smaller than in the classical formulation. A boundary element analysis of three-dimensional fracture mechanics problems of transversely isotropic solids based on the mixed formulation is presented in this paper. The hypersingular and strongly singular kernels appearing in the formulation are regularized by using two terms of the displacement series expansion and one term of the traction expansion, at the collocation point. All the remaining integrals are analytically evaluated or transformed by means of Stokes' theorem into regular or weakly singular integrals, which are numerically computed. The method is general and can be used for elements of any shape including quarter-point crack front elements. No change of co-ordinates is required for the integration. The formulation as presented in this paper is something as clear, general and easy to handle as the classical BE formulation. It is used in combination with three-dimensional quadratic and quarter-point elements to obtain accurate results for several different crack problems. Cracks in boundless and finite transversely isotropic domains are studied. The meshes are simple and include only discretization of the crack and the external boundary. The obtained results are in good agreement with those existing in the literature. Copyright © 2004 John Wiley & Sons, Ltd. [source] Detecting microdamage in boneJOURNAL OF ANATOMY, Issue 2 2003T. C. Lee Abstract Fatigue-induced microdamage in bone contributes to stress and fragility fractures and acts as a stimulus for bone remodelling. Detecting such microdamage is difficult as pre-existing microdamage sustained in vivo must be differentiated from artefactual damage incurred during specimen preparation. This was addressed by bulk staining specimens in alcohol-soluble basic fuchsin dye, but cutting and grinding them in an aqueous medium. Nonetheless, some artefactual cracks are partially stained and careful observation under transmitted light, or epifluorescence microscopy, is required. Fuchsin lodges in cracks, but is not site-specific. Cracks are discontinuities in the calcium-rich bone matrix and chelating agents, which bind calcium, can selectively label them. Oxytetracycline, alizarin complexone, calcein, calcein blue and xylenol orange all selectively bind microcracks and, as they fluoresce at different wavelengths and colours, can be used in sequence to label microcrack growth. New agents that only fluoresce when involved in a chelate are currently being developed , fluorescent photoinduced electron transfer (PET) sensors. Such agents enable microdamage to be quantified and crack growth to be measured and are useful histological tools in providing data for modelling the material behaviour of bone. However, a non-invasive method is needed to measure microdamage in patients. Micro-CT is being studied and initial work with iodine dyes linked to a chelating group has shown some promise. In the long term, it is hoped that repeated measurements can be made at critical sites and microdamage accumulation monitored. Quantification of microdamage, together with bone mass measurements, will help in predicting and preventing bone fracture failure in patients with osteoporosis. [source] Collagen architecture and failure processes in bovine patellar cartilageJOURNAL OF ANATOMY, Issue 4 2001JACK L. LEWIS Cartilage fails by fibrillation and wearing away. This study was designed to identify the microscopic failure processes in the collagen network of bovine cartilage using scanning electron microscopy. Cartilage samples from fibrillated cartilage from the bovine patella were removed from the bone, fixed, digested to remove proteoglycans, freeze-fractured, and processed for SEM. The architecture of the collagen network in the normal cartilage was first defined, and then the failure processes were identified by examining sites of fibrillation and at crack tips. The bovine patellar cartilage was organised with a superficial layer composed of 3,5 lamina, attached to a sub-superficial tissue by angled bridging fibrils. Collagen in the sub-superficial tissue was organised in lamina oriented in the radial direction up to the transition zone. Failure of the system occurred by cracks forming in superficial layer and lamina, creating flaps of lamina that rolled up into the larger ,fronds'. Larger cracks not following the laminar planes occurred in the transition, mid, and deep zones. Failure at the crack tips in the sub-superficial tissue appeared to be by peeling of collagen fibrils, as opposed to breaking of collagen fibrils, suggesting a ,glue' bonding the collagen fibrils in a parallel fashion. Cracks propagated by breaking these bonds. This bond could be a site of disease action, since weakening of the bond would accelerate crack propagation. [source] Definitive Diagnosis of Early Enamel and Dentin Cracks Based on Microscopic EvaluationJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 7 2003DAVID J. CLARK DDS [source] Mechanism for Salt ScalingJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2006John J. Valenza II Over the past 60 years, concrete infrastructure in cold climates has deteriorated by "salt scaling," which is superficial damage that occurs during freezing in the presence of saline water. It reduces mechanical integrity and necessitates expensive repair or replacement. The phenomenon can be demonstrated by pooling a solution on a block of concrete and subjecting it to freeze/thaw cycles. The most remarkable feature of salt scaling is that the damage is absent if the pool contains pure water, it becomes serious at concentrations of a few weight percent, and then stops at concentrations above about 6 wt%. In spite of a wealth of research, the mechanism responsible for this damage has only recently been identified. In this article, we show that salt scaling is a consequence of the fracture behavior of ice. The stress arises from thermal expansion mismatch between ice and concrete, which puts the ice in tension as the temperature drops. Considering the mechanical and viscoelastic properties of ice, it is shown that this mismatch will not cause pure ice to crack, but moderately concentrated solutions are expected to crack. Cracks in the brine ice penetrate into the substrate, resulting in superficial damage. At high concentrations, the ice does not form a rigid enough structure to result in significant stress, so no damage occurs. The morphology of cracking is predicted by fracture mechanics. [source] Laminar Ceramics Utilizing the Zirconia Tetragonal-to-Monoclinic Phase Transformation to Obtain a Threshold StrengthJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2002Michael G. Pontin Ceramic laminates have been fabricated with thin layers, containing a mixture of unstabilized zirconia (MZ-ZrO2) and alumina (Al2O3), sandwiched between thicker layers of alumina that contain a small fraction of Y2O3 -stabilized tetragonal ZrO2 to inhibit grain growth. The MZ-ZrO2 undergoes a tetragonal-to-monoclinic phase transformation during cooling to produce biaxial compressive stresses in the thin layers. Cracks that extend within the thicker alumina layers can be arrested by the compressive layers to produce a threshold strength, i.e., a strength below which the probability of failure is zero. Laminates composed of Al2O3 layers 315 ± 15 ,m thick and Al2O3/MZ-ZrO2 layers 29 ± 3 ,m thick exhibit a threshold strength of 507 ± 36 MPa, regardless of the MZ-ZrO2 content, for volume fractions ,0.35. These results, piezospectroscopic stress measurements, and microstructural observations suggest that microcracking produced during the transformation reduces the magnitude of the compressive stresses achieved, which in turn limits the magnitude of the threshold strength. [source] Crack Growth in Soda,Lime,Silicate Glass near the Static Fatigue LimitJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2002Sheldon M. Wiederhorn The atomic force microscope (AFM) was used to explore the nature of features formed on the surfaces of cracks in soda,lime,silicate glass that were held at stress intensity factors below the crack growth threshold. All studies were conducted in water. Cracks were first propagated at a stress intensity factor above the crack growth threshold and then arrested for 16 h at a stress intensity factor below the threshold. The stress intensity factor was then raised to reinitiate crack growth. The cycle was repeated multiple times, varying the hold stress intensity factor, the hold time, and the propagation stress intensity factor. Examination of the fracture surface by optical microscopy showed surface features that marked the points of crack arrest during the hold time. These features were identical to those reported earlier by Michalske in a similar study of crack arrest. A study with the AFM showed these features to be a consequence of a bifurcation of the crack surface. During the hold period, waviness developed along the crack front so that parts of the front propagated out of the original fracture plane, while other parts propagated into the plane. Crack growth changed from the original flat plane to a bifurcated surface with directions of as much as 3° to 5° to the original plane. This modification of crack growth behavior cannot be explained by a variation in the far-field stresses applied to the crack. Nor can the crack growth features be explained by chemical fluctuations within the glass. We speculate that changes in crack growth direction are a consequence of an enhancement in the corrosion rate on the flank of the crack at stresses below the apparent crack growth threshold in a manner described recently by Chuang and Fuller. [source] Effects of Matrix Cracks on the Thermal Diffusivity of a Fiber-Reinforced Ceramic CompositeJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2001Kathleen R. McDonald Effects of matrix cracks and the attendant interface debonding and sliding on both the longitudinal and the transverse thermal diffusivities of a unidirectional Nicalon/MAS composite are investigated. The diffusivity measurements are made in situ during tensile testing using a phase-sensitive photothermal technique. The contribution to the longitudinal thermal resistance from each of the cracks is determined from the longitudinal diffusivity along with measurements of crack density. By combining the transverse measurements with the predictions of an effective medium model, the thermal conductance of the interface (characterized by a Biot number) is determined and found to decrease with increasing crack opening displacement, from an initial value of ,1 to ,0.3. This degradation is attributed to the deleterious effects of interface sliding on the thermal conductance. Corroborating evidence of degradation in the interface conductance is obtained from the inferred crack conductances coupled with a unit cell model for a fiber composite containing a periodic array of matrix cracks. Additional notable features of the material behavior include: (i) reductions of ,20% in both the longitudinal and the transverse diffusivities at stresses near the ultimate strength, (ii) almost complete recovery of the longitudinal diffusivity following unloading, and (iii) essentially no change in the transverse diffusivity following unloading. The recovery of the longitudinal diffusivity is attributed to closure of the matrix cracks. By contrast, the degradation in the interface conductance is permanent, as manifest in the lack of recovery of the transverse diffusivity. [source] Thermal Conductance of Delamination Cracks in a Fiber-Reinforced Ceramic CompositeJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2000Kathleen R. McDonald The thermal conductance of delamination cracks in a unidirectionally reinforced ceramic composite is investigated. A phase-sensitive photothermal technique is used to measure the crack conductance in situ under load. Special emphasis is given to the effects of the local crack opening displacement (,). A crack conductance model that considers the contributions from both the air and the fibers within the crack is developed and compared with the measurements. Despite considerable scatter in the experimental data, the model adequately predicts the increased conductance that is associated with fiber bridging, as well as the overall trend that is observed with ,. [source] Effect of Atmospheric Humidity on the Fatigue Crack Propagation Behavior of Short Cracks in Silicon NitrideJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2000Sotomi Ishihara The effect of the environment on crack-growth processes in silicon nitride was studied by investigating the static and fatigue crack-growth behavior of small surface cracks, as influenced by testing (i) in the ambient environment, (ii) in distilled water, (iii) under vacuum, and (iv) in toluene. A principal finding was that testing under cyclic conditions led to crack-growth rates that were much higher in air than in toluene, whereas testing under static conditions in air or toluene led to minor differences in the rate of static fatigue crack growth. This difference in sensitivity to the environment under static and cyclic loading conditions was attributed, in part, to a much-greater extent of microcracking at the surface ahead of the main crack in air under cyclic conditions, in comparison to that in other environments. This propensity for microcracking at the surface in air under cyclic conditions also was reflected in the aspect ratios of the crack shapes that developed. [source] Crack Tip Morphology of Slowly Growing Cracks in GlassJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2000Stéphane Hénaux We present atomic force microscopy (AFM) observations of crack tips in glass during subcritical propagation. These have been obtained by means of an AFM sample holder which has been specially designed to propagate indentation cracks in glass plates. Crack tips in soda,lime,silica glass are always preceded by a few nanometers deep deformation. In vitreous silica, no other surface deformation than the crack itself could be detected. For both materials, the crack opening is found to largely exceed the elastic solution. [source] MOVPE high quality GaN film grown on Si (111) substrates using a multilayer AlN bufferPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2008Kung-Liang Lin Abstract High quality GaN films were successfully grown on Si (111) substrates using the MOVPE method and a multilayer AlN buffer. The buffer layer film quality and thickness are critical for the growth of the crack-free GaN film on Si (111) substrates. Cracks started to form on the single layer high temperature (HT) AlN film grown on Si (111) substrate as the AlN thickness was greater than 20 nm. However, a 100 nm crack-free AlN film can be obtained when multilayer buffer of HT-AlN/low temperature (LT)-AlN/HT-AlN was grown on the Si (111) substrate. By using multilayer AlN buffer, a 2 ,m crack-free GaN film was successful grown on the 2" Si (111) substrate. Moreover, the GaN film (2,m thick) grown on Si with a GaN (004) Mosaic FWHM of only 0.12°. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Cracks and the Crisis of Abstract LabourANTIPODE, Issue 4 2010John Holloway Abstract:, In this article I suggest that the key to understanding autonomies is the revolt of one form of activity against another. I relate this revolt to Marx's concept of the dual character of labour, and suggest that the rise of autonomist politics should be understood as an expression of the crisis of abstract labour. [source] Committing to regional cooperation: ASEAN, globalisation and the Shin Corporation , Temasek Holdings dealASIA PACIFIC VIEWPOINT, Issue 3 2009Sajid Anwar Abstract This paper investigates the relationship between regional and national identities in the age of globalisation, with particular reference to the Association of Southeast Asian Nations (ASEAN). For members of ASEAN, economic integration is seen as a necessary step forward in order to (i) reduce reliance on Western countries during times of economic crisis and (ii) speed up the recovery process in the aftermath of a crisis. The concept of an ASEAN Economic Community represents a step towards achieving this goal. However, by means of a case study, this paper demonstrates that the idea of an ASEAN Economic Community does not yet have sufficiently solid foundations. Cracks appear when member states act in response to national interest. Given the frequency of friction between member nations, and the fact that ASEAN members are quite diverse in both economic and cultural respects, there is still much more to be done to realise the objective of forming an effective and credible regional economic group. In this paper some suggestions are offered that might assist with the achievement of this goal. [source] Der Eurocode 2 für Deutschland , Erläuterungen und HintergründeBETON- UND STAHLBETONBAU, Issue 8 2010Rissbreiten und Verformungen, Teil 3: Begrenzung der Spannungen Berechnung- und Bemessungsverfahren; Normen, Vorschriften, Richtlinien Abstract Der neue Eurocode 2: "Bemessung und Konstruktion von Stahlbeton- und Spannbetontragwerken , Teil 1-1: Allgemeine Bemessungsregeln und Regeln für den Hochbau" (EC2-1-1) mit seinem Nationalen Anhang ist nach einer ausführlichen Erprobungsphase bereit zur bauaufsichtlichen Einführung in Deutschland. In mehreren Beiträgen sollen Erläuterungen und Hintergründe zu einigen Regelungen im Eurocode 2 und zu den Entscheidungen für Regeln im Nationalen Anhang vorgestellt werden, die entweder zu Änderungen gegenüber DIN 1045-1 oder zu Abweichungen vom Eurocode 2 führten. Der Teil 3 enthält Erläuterungen zur Begrenzung der Spannungen, Rissbreiten und Verformungen. The Eurocode 2 for Germany , Explanations and Backgrounds Part 3: Limitation of Stresses, Cracks and Deformations The new Eurocode 2 "Design of concrete structures , Part 1-1: General rules and rules for buildings" (EC2-1-1) and its National Annex has undergone a phase of detailed testing and is now ready for the implementation in Germany. In some articles should be given explanations and backgrounds of some rules in Eurocode 2 and of decisions for rules in the National Annex, which have been taken either to changes compared with DIN 1045-1 or to differences to Eurocode 2. Article 3 contains explanations for the limitation of stresses, cracks and deformations. [source] Joined-Up Services for Young Children and Their Families: Papering Over the Cracks or Re-Constructing the Foundations?CHILDREN & SOCIETY, Issue 2 2007Jo Warin The idea that services can be provided for young children within their families in a seamless way that serves the interests of children and families simultaneously is problematic. A theoretical flaw underpinning the ideal of integrated services is that families are assumed to be homogenous units. This article explores competing goals for children and families by examining data from the evaluation of three Early Excellence Centres in the north of England piloted by the Department for Education and Employment from 1999 to 2002. The article recommends that extended childcare services should be clearly targeted to the needs of the child-within-the-family, thereby providing a clear theoretical foundation for re-conceptualising joined-up services. © 2006 The Author(s). Journal compilation © 2006 National Children's Bureau. [source] Identifying Injection Drug Users at Risk of Nonfatal OverdoseACADEMIC EMERGENCY MEDICINE, Issue 7 2007Phillip O. Coffin MD Objectives:Drug overdose is the second leading cause of accidental deaths among U.S. adults aged 15,64 years. Emergency physicians have a unique opportunity to provide overdose prevention interventions, because habitual drug users are in frequent need of medical care. The authors evaluated associations between individual-level risk factors and experiencing an overdose in the past six months to determine which characteristics and behaviors may be most predictive of overdose. Methods:The authors used data from a sample of street-recruited habitual drug users who participated in face-to-face interviews about overdose from November 2001 to February 2004. This analysis was restricted to 772 respondents who had been injecting for at least one year and who had injected heroin within the past two months. Results:A total of 16.6% of participants had overdosed in the past six months. Characteristics and behaviors that were independently associated with an increased risk of a recent overdose were having had a prior overdose (odds ratio [OR], 28.58; 95% confidence interval [CI] = 14.10 to 57.96), using cocaine/crack in the past six months (OR, 2.07; 95% CI = 1.25 to 3.45), using alcohol in the past six months (OR, 1.90; 95% CI = 1.01 to 3.57), experiencing serious withdrawal symptoms in the past two months (OR, 2.70; 95% CI = 1.58 to 4.61), and younger age. Conclusions:Drug users who have previously experienced a nonfatal overdose are at very high risk of experiencing future overdoses. Further longitudinal studies are needed to identify robust predictors of overdose risk over time in habitual drug users, but these data suggest that drug users who have overdosed warrant aggressive prevention efforts such as agonist maintenance treatment or provision of take-home naloxone. [source] A Study on the Effects of Damage Models and Wavelet Bases for Damage Identification and Calibration in BeamsCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 8 2007Vikram Pakrashi A numerical study has been performed in this article addressing these issues for single and multispan beams with an open crack. The first natural modeshapes of single and multispan beams with an open crack have been simulated considering damage models of different levels of complexity and analyzed for different crack depth ratios and crack positions. Gaussian white noise has been synthetically introduced to the simulated modeshape and the effects of varying signal-to-noise ratio have been studied. A wavelet-based damage identification technique has been found to be simple, efficient, and independent of damage models and wavelet basis functions, once certain conditions regarding the modeshape and the wavelet bases are satisfied. The wavelet-based damage calibration is found to be dependent on a number of factors including damage models and the basis function used in the analysis. A curvature-based calibration is more sensitive than a modeshape-based calibration of the extent of damage. [source] EXAMINING THE "CRIMINAL CAREERS" OF PROSTITUTES WITHIN THE NEXUS OF DRUG USE, DRUG SELLING, AND OTHER ILLICIT ACTIVITIES,CRIMINOLOGY, Issue 3 2000SHEILA ROYO MAXWELL This paper examines the co-occurrence of prostitution, drug use, drug selling, and involvement in non-drug crimes among women who have used serious drugs (e.g., crack, heroin). Existing perspectives on the drug use-prostitution nexus are re-examined using three dimensions of the criminal career paradigm: prevalence, lambda, and age of onset. Results show that approximately one-half of the women who reported regular drug use never prostituted, and that, except for use of crack cocaine, use of other drugs was unrelated to the prevalence, frequency, or age of onset into prostitution. The results also show that committing property crime was associated with an increased prevalence and early onset into prostitution, while selling drugs coincided with a decreased prevalence and delayed onset into prostitution. [source] Growth and characterization of magneto-optical YFeO3 crystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2007Hui Shen Abstract The floating zone growth of magneto-optical crystal YFeO3 has been investigated. The polycrystalline feed rod was prepared by a pressure of 250MPa and sintering at about 1500°C. A crack- free YFeO3 single crystal has been successfully grown. The crystal preferred to crystallize along <100> direction with about 10° deviation. The X-ray rocking curve of the crystal has a FWHM of 24 arcsec, confirming the high crystal quality of the sample. The (100) plane was etched by hot phosphoric acid and the dislocation density was about 104/cm2. A thin outer layer with Y2O3 -rich composition was found at the periphery of as-grown crystals, which was attributed to the Fe2O3 evaporation during growth. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Analysis of 154 cases of teeth with cracksDENTAL TRAUMATOLOGY, Issue 3 2006Byoung-Duck Roh Abstract,,, It is well known that cracked teeth occur most frequently in the mandibular molars with large or poor restorations, in those over 50 years of age. However, with increasing knowledge and experience with cracks of teeth, cracks appear to be found frequently in intact teeth without restorations. The aim of this study is to analyze the cases of tooth cracks in a dental hospital in a year, and to find out the characteristic features of cracks of teeth. For 1 year, each tooth that were identified as a cracked tooth was recorded and analyzed in terms of the classification of cavity and restorative material, the nature of opposing tooth, the location in the arch, the age and gender, and the clinical signs and symptoms, and treatment result. Cracked teeth were observed most frequently in the teeth with no restorations (60.4%) and with class I restorations (29.2%). The most prevalent age was in those over 40 years of age (31.2% in their 40s, 26.6% in their 50s) and the prevalence was similar in men (53.9%) and women (46.1%). Cracked teeth were found most frequently in the maxillary molars (33.8% in first molar, 23.4% in second molar) than in the mandibular molars (20.1% in first molar, 16.2% in second molar). 96.1% of the cracked teeth responded to the bite test, and 81.1% of the cracked teeth were observed in the mesiodistal direction. The prevalence of cracked tooth was highest in the intact teeth with no restoration, in maxillary molars, and in those over 40 years of age. When examining a intact maxillary posterior tooth that is sensitive to a bite and thermal change, crack in the mesiodistal direction need to be considered one of the causes. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||