Possible correlation between work-hardening and fatigue-failure

Conceptual theory proposes that cyclic hardening due to non-uniform strain and stress amplitudes during testing, especially during the initial application of stress to a specimen, may correlate positively with the ultimate strength of the specimen under test

Is inner core seismic anisotropy a marker of plastic flow of cubic iron?

This paper investigates whether observations of seismic anisotropy are compatible with a cubic structure of the inner core Fe alloy. We assume that anisotropy is the result of plastic deformation within a large scale flow induced by preferred growth at the inner core equator. Based on elastic moduli from the literature, bcc- or fcc-Fe produce seismic anisotropy well below seismic observations (\textless{}0.4\%). A Monte-Carlo approach allows us to generalize this result to any form of elastic anisotropy in a cubic system. Within our model, inner core global anisotropy is not compatible with a cubic structure of Fe alloy. Hence, if the inner core material is indeed cubic, large scale coherent anisotropic structures, incompatible with plastic deformation induced by large scale flow, must be present

Structural setting and petrogenesis of Silurian granites in the Caledonides of northern Scotland

nappes, the Moine and Naver nappes, contain a series of granitic plutons. The Rogart, Strath Halladale and Helmsdale granites have been studied using field and microstructural fabric analysis. Their emplacement mechanisms and pre, syn or post-tectonic status with respect to phases of Caledonian ductile deformation have been detailed. The petrogenesis of the Strath Halladale and Helmsdale granites has been examined within the framework of a regional geochemical study involving nine Caledonian high Ba-Sr granitoids. The foliated Strath Halladale Granite comprises a series of easterly-dipping sheets that were intruded into structurally high parts of the Naver Nappe in northeastern Sutherland. The granite contains magmatic-state shear zones that consistently show top-to-the- W-to- NW sense of movement; it was emplaced during Caledonian (02) west-directed thrusting. The Rogart Granite was emplaced into the footwall of the Naver Thrust in southeastern Sutherland. It comprises early, sheeted quartz diorites that carry magmatic to solid-state fabrics formed by thrust-related, west-directed ductile deformation and a central igneous quartz monzodiorite-granodiorite-granite complex that ballooned into a tectonically created void formed along the Strath Fleet Lineament after D2 thrusting. The emplacement of the Rogart Granite encompassed the switchover from west-directed thrusting to strike-slip tectonics in this area. The Helmsdale Granite was emplaced into the highest parts of the Naver Nappe in eastern Sutherland. It does not contain any emplacement-related or tectonically-induced fabrics and is post-tectonic with respect to Caledonian deformation. Its emplacement mechanism and hence the Caledonian significance of the adjacent Helmsdale Fault remain speculative. Geochemistry confirms that the Strath Halladale and Helmsdale granites are part of the Caledonian high Ba-Sr granites (sensu Tarney & Jones 1994) and indicates melt evolution by assimilation fractional crystallization (AFC) involving Moine metasediment. Associated mafic rocks do not form parents to the granites but represent a variety of genetically-related cumulates. Nine Caledonian high Ba-Sr plutons in northern Scotland show a systematic isotopic variability. Plutons with the highest 87Sr/86Sr(i)have the lowest ENd(i) and the highest 8180, whereas plutons with lower 87Sr/86Sr(i)have complementary higher ENd(i) and lower 8180. Syenite-dominated complexes evolved by assimilation fractional crystallization (AFC) involving depleted granulite-facies basement whereas the granites assimilated Moine metasediment. Combining available age data with the observed isotope systematics suggests, that the syenites recorded progressive (source) enrichment over c. 30 Ma followed by a short-lived, isotopically-diverse, magmatic pulse at c. 425 Ma

U-Pn geochronology of deformed metagranites in central Sutherland, Scotland: evidence for widespread late Silurian metamorphism and ductile deformation of the Moine Supergroup during the Caledonian orogeny

Within the Caledonides of central Sutherland, Scotland, the Neoproterozoic metasedimentary rocks of the Moine Supergroup record NW-directed D2 ductile thrusting and nappe assembly, accompanied by widespread tight-to-isoclinal folding and amphibolite-facies metamorphism. A series of metagranite sheets which were emplaced and penetratively deformed during D2 have been dated using SHRIMP UâPb geochronology. Zircon ages of 424 8 Ma (Vagastie Bridge granite), 420 6 Ma (Klibreck granite) and 429 11 Ma (Strathnaver granite) are interpreted to date emplacement, and hence regional D2 deformation, during mid- to late Silurian time. Titanite ages of 413 3 Ma (Vagastie Bridge granite) and 416 3 Ma (Klibreck granite) are thought to date post-metamorphic cooling through a blocking temperature of c. 550â 500 8C. A mid- to late Silurian age for D2 deformation supports published models that have viewed the internal ductile thrusts of this part of the orogen as part of the same kinematically linked system of forelandpropagating thrusts as the marginal Moine Thrust Zone. The new data contrast with previous interpretations that have viewed the dominant structures and metamorphic assemblages within the Moine Supergroup as having formed during the early to mid-Ordovician Grampian arcâcontinent orogeny. The mid-to late Silurian D2 nappe stacking event in Sutherland is probably a result of the collision of Baltica with the Scottish segment of Laurentia

Reducing information asymmetry in used-car markets by using machine learning models

Information asymmetry in used-car markets results from knowledge differences between buyers and sellers about used cars. Naturally, someone who owns a used car for a certain period, develops a deeper understanding of the real value opposed to someone who did not. The goal of this work is to attempt to reduce information asymmetry in used-car markets by using state-of-the-art machine learning models. With data provided by a Polish used-car online marketplace, a price range estimation as well as a point estimation will be made for every car. A Median Absolute Percentage Error of 7.86%and Target Zone of 58.38% are achieved

Immunogenicity of a lowcost hepatitis Bvaccine in the South African Expanded Programme on Immunisation

Background. A low-cost, 'flash' heat-inactivated hepatitis B vaccine with enhanced immunogenicity allowing for a relatively low dose (Hepaccine B; Cheil Foods and Chemicals, Korea) was introduced into the South African Expanded Programme on Immunisation during 1995 to immunise infants against hepatitis B. To detennnine the seroresponse of this vaccine in South Africa, a country with a high hepatitis B virus (HBV) prevalence, a field trial was conducted in a rural health clinic.Methods. The immunogenicity of Hepaccine B, containing 1.5IJg/O.5 ml, was studied in 186 black infants attending the Soshanguve III clinic, north-west of Pretoria. Infants receiving three consecutive doses in the anterolateral thigh at 6,10 and 14 weeks were monitored. The doses were administered concurrently with their routine oral polio vaccine (OPV) and diphtheria, pertussis and tetanus (DPT) immunisations. Vaccine side-effects were recorded. Blood specimens were collected 3 months after the final vaccination. Sera were tested for antibodies to hepatitis B surface antigen (anti-HBs) by IMx AUSAB (Abbott Laboratories, USA). Levels of anti-HBs were determined by comparison with standard reference preparations and expressed in mlUlml.Results. Side-effects of the vaccine were minor, with limited local reaction at the site of administration. The· anti-HBs seroconversion rate was 93.0%, based on a titre of ~ 10 mlUlml with a geometric mean titre of 257.58 mlUlml.Conclusions. Administration of 1.5 I-Ig doses of Hepaccine B at 6, 10 and 14 weeks is safe and highly immunogenic in black South African infants, and this vaccine is suitable for use in countries with high HBV prevalences such as in Africa. The use of an economical hepatitis B vaccine would greatly facilitate the prevention of hepatitis B in these countries

Towards health status guided care in COPD:Using the clinical COPD questionnaire (CCQ)

COPD questionnaire good alternative for pulmonary function measurement Patients suffering from chronic obstructive pulmonary disease (COPD) are currently treated based on pulmonary function measurements. However, although pulmonary function determines the gravity of the disease, it bears little relation to the number of complaints experienced by COPD patients. According to research by UMCG PhD candidate Janwillem Kocks, measuring these complaints and patients’ health status with a questionnaire proves useful in guiding COPD treatment in daily practice. The questionnaire is also able to accurately predict how the disease will develop during a hospital stay. Kocks will be awarded a PhD by the University of Groningen on 1 June 2011. Taken together, the number of complaints and their impact on daily life are known as health status. To determine health status in the event of COPD, questionnaires have been developed and validated. De Clinical COPD Questionnaire (CCQ) comprises 10 questions in three categories: complaints, functional status (what patients are capable of and what they do in practice) and mental status (how they feel about this). Until now, questionnaires were more often used for scientific research purposes than to treat individual patients. Kocks investigated the conditions and possibilities of guiding COPD treatment based on the CCQ, rather than solely on pulmonary function. Reliability The quality required for a questionnaire used to treat individual patients is higher than the quality necessary for one used to measure matters in patient groups. In his research, Kocks studied the reliability of the CCQ when used in treatment at an individual level. To do so, he compared the questionnaire scores of patients and doctors. Patients completed the questionnaire before visiting their lung specialist. After the consultation, the specialist completed the questionnaire about the patient in the manner he or she thought the patient should have filled it in. The patients were then interviewed in depth and the information this yielded was given to a number of lung specialists and GPs to use in completing the questionnaire. All of the physicians’ judgments were compared to the patients’, and this showed that the scores matched well. Kocks concluded that the CCQ can be used as a reliable tool for individual patients in daily practice. The Netherlands appears to be leading the way in using the concept of health status – or the burden of disease – to guide the treatment of COPD. Predicting health status development The use of the CCQ during a hospital stay due to an acute case of COPD exacerbation was also investigated. The health status as measured by the CCQ proved able to predict how quickly patients would need to be put on intensive care, would need to be readmitted after being discharged or would die. This differs greatly from often used measurements such as blood oxygen levels or the degree of shortness of breath experienced, which cannot properly predict the course of disease in this group of patients. Kocks found that practitioners were able to glean lots of additional and valuable information from the CCQ when patients were experiencing COPD exacerbation. Curriculum Vitae Janwillem Kocks (Zwolle, 1980) studied medicine at the University of Groningen and then specialized as a general practitioner (GP). While training as a GP, he conducted his PhD research at the UMCG’s General Practice Medicine department and its Groningen Research Institute for Asthma and COPD (GRIAC). Kocks’s thesis is entitled ‘Towards health status guided care in COPD using the Clinical COPD Questionnaire’. Kocks will continue to work as a GP with the Academische Huisartsenpraktijk Groningen (Groningen Academic GP post) and as a researcher at the General Practice Medicine department at the UMCG. Available hardcopies of this thesis could be obtain through the author: [email protected]