3,618 research outputs found

    Increased sclerostin associated with stress fracture of the third metacarpal bone in the Thoroughbred Racehorse

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    Abstract Objectives: The exact aetiopathogenesis of microdamage induced long bone fractures remains unknown. These fractures are likely the result of inadequate bone remodeling in response to damage. This study aims to identifiesy an association of osteocyte apoptosis, the presence of osteocytic osteolysis and any alterations in sclerostin expression with fracture of the third metacarpal bone of (Mc-III) thoroughbred (TB) racehorses. Methods: 30 Mc-III bones were obtained; 10 from bones fractured during racing, 10 from the contralateral limb and 10 from control horses. Each Mc- III bone was divided into fracture site, condyle, condylar groove and sagittal ridge. Microcracks and diffuse microdamage were quantified. Apoptotic osteocytes were measured using TUNEL staining. Cathepsin K, matrix metalloproteinase -13 (MMP-13), HtrA1 and sclerostin expression was analysed. of apoptotic cells between contralateral limb and unraced control, however, there were significantly less apoptotic cells in fractured samples (p<0.02). Immunohistochemistry showed that in the deep zones of the fractured samples sclerostin expression was significantly higher (p<0.03) of the total number of osteocytes. No increase in cathepsin K, MMP-13 or HtrA1 was present

    Creep fatigue of low-cobalt superalloys: Waspalloy, PM U 700 and wrought U 700

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    The influence of cobalt content on the high temperature creep fatigue crack initiation resistance of three primary alloys was evaluated. These were Waspalloy, Powder U 700, and Cast U 700, with cobalt contents ranging from 0 up to 17 percent. Waspalloy was studied at 538 C whereas the U 700 was studied at 760 C. Constraints of the program required investigation at a single strain range using diametral strain control. The approach was phenomenological, using standard low cycle fatigue tests involving continuous cycling tension hold cycling, compression hold cycling, and symmetric hold cycling. Cycling in the absence of or between holds was done at 0.5 Hz, whereas holds when introduced lasted 1 minute. The plan was to allocate two specimens to the continuous cycling, and one specimen to each of the hold time conditions. Data was taken to document the nature of the cracking process, the deformation response, and the resistance to cyclic loading to the formation of small cracks and to specimen separation. The influence of cobalt content on creep fatigue resistance was not judged to be very significant based on the results generated. Specific conclusions were that the hold time history dependence of the resistance is as significant as the influence of cobalt content and increased cobalt content does not produce increased creep fatigue resistance on a one to one basis

    On the Gold Standard for Security of Universal Steganography

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    While symmetric-key steganography is quite well understood both in the information-theoretic and in the computational setting, many fundamental questions about its public-key counterpart resist persistent attempts to solve them. The computational model for public-key steganography was proposed by von Ahn and Hopper in EUROCRYPT 2004. At TCC 2005, Backes and Cachin gave the first universal public-key stegosystem - i.e. one that works on all channels - achieving security against replayable chosen-covertext attacks (SS-RCCA) and asked whether security against non-replayable chosen-covertext attacks (SS-CCA) is achievable. Later, Hopper (ICALP 2005) provided such a stegosystem for every efficiently sampleable channel, but did not achieve universality. He posed the question whether universality and SS-CCA-security can be achieved simultaneously. No progress on this question has been achieved since more than a decade. In our work we solve Hopper's problem in a somehow complete manner: As our main positive result we design an SS-CCA-secure stegosystem that works for every memoryless channel. On the other hand, we prove that this result is the best possible in the context of universal steganography. We provide a family of 0-memoryless channels - where the already sent documents have only marginal influence on the current distribution - and prove that no SS-CCA-secure steganography for this family exists in the standard non-look-ahead model.Comment: EUROCRYPT 2018, llncs styl

    Participant recruitment to FiCTION, a primary dental care trial – survey of facilitators and barriers

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    Objective To identify reasons behind a lower than expected participant recruitment rate within the FiCTION trial, a multi-centre paediatric primary dental care randomised controlled trial (RCT). Subjects (materials) and methods An online survey, based on a previously published tool, consisting of both quantitative and qualitative responses, completed by staff in dental practices recruiting to FiCTION. Ratings from quantitative responses were aggregated to give overall scores for factors related to participant recruitment. Qualitative responses were independently grouped into themes. Results Thirty-nine anonymous responses were received. Main facilitators related to the support received from the central research team and importance of the research question. The main barriers related to low child eligibility rates and the integration of trial processes within routine workloads. Conclusions These findings have directed strategies for enhancing participant recruitment at existing practices and informed recruitment of further practices. The results help provide a profile of the features required of practices to successfully screen and recruit participants. Future trials in this setting should consider the level of interest in the research question within practices, and ensure trial processes are as streamlined as possible. Research teams should actively support practices with participant recruitment and maintain enthusiasm among the entire practice team

    Extremely asymmetrical scattering in gratings with varying mean structural parameters

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    Extremely asymmetrical scattering (EAS) is an unusual type of Bragg scattering in slanted periodic gratings with the scattered wave (the +1 diffracted order) propagating parallel to the grating boundaries. Here, a unique and strong sensitivity of EAS to small stepwise variations of mean structural parameters at the grating boundaries is predicted theoretically (by means of approximate and rigorous analyses) for bulk TE electromagnetic waves and slab optical modes of arbitrary polarization in holographic (for bulk waves) and corrugation (for slab modes) gratings. The predicted effects are explained using one of the main physical reasons for EAS--the diffractional divergence of the scattered wave (similar to divergence of a laser beam). The approximate method of analysis is based on this understanding of the role of the divergence of the scattered wave, while the rigorous analysis uses the enhanced T-matrix algorithm. The effect of small and large stepwise variations of the mean permittivity at the grating boundaries is analysed. Two distinctly different and unusual patterns of EAS are predicted in the cases of wide and narrow (compared to a critical width) gratings. Comparison between the approximate and rigorous theories is carried out.Comment: 16 pages, 5 figure

    Dealing with Complexity: Infant Feeding Choices and Experiences for Mothers with Infants in Neonatal Intensive Care Units and Transitional Care Wards

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    EXECUTIVE SUMMARY The central aim of the research on which this document reports was: To explore the knowledge, perceptions and experiences of infant feeding of mothers with infants in neonatal intensive care units (NICU) and transitional care wards (TCW) and the support these mothers receive from healthcare professionals and significant others with the aim of contributing to further support of mothers, significant others and healthcare professionals in the future. The objectives were: 1. To explore mothers’ with infants in NICU knowledge and understanding of infant, feeding and how this influences feeding choices. 2. To gain an understanding of mothers experiences of infant feeding, 3. To investigate the challenges of infant feeding in NICU. 4. To explore the significance of their self-identity and perception as ‘good’ or ‘not so good’ mothers in relation to this choice. 5. To ascertain the support women receive from healthcare professionals and significant others. 6. To identify further research needs, develop service provision and inform practice and policy. Background to the study is supported by a review of the clinical and sociologically relevant literature and brief detail on a previous related study (Stenhouse and Letherby 2013) which focused on the experience of mothers’ whose pregnancies were complicated by diabetes. A mixed method ethnographic approach was adopted: • Observations in the NICU and TCW were undertaken (alongside interviewing) amounting to approximately six hours. • One-to-one and dyad/group interviewing were undertaken with mothers and some of their partners. • Questionnaires (consisting of 10 questions, some of which were open to allow more respondent input) were distributed to all healthcare professionals working in NICU and TCW. An audit involving a systematic and independent examination of maternal and infant notes was undertaken at the same time as the primary data was collected. DATA AND DISCUSSION The Audit: This section provides a snapshot of infant feeding and expression of breastmilk from a cohort of mothers and babies who had previously been cared for in NICU, TCW or both. Appendix IV is a copy of a poster presented as part of the Medical Training Special Studies Unit. Interview and Questionnaire Data: This section reports on data collected from women, significant others and healthcare professionals and includes detailed reference to the significance of ‘The Journey’, the mixed experience of ‘Skills and Support’ and the experiences of ‘Pleasure, Pressure and Propaganda’. CONCLUSIONS, IMPLICATIONS AND RECOMMENDATIONS Six summary points 1. Training for staff is mixed and this is linked to confidence in supporting women. 2. Women ‘sensed’ the lack of confidence of some staff and this caused anxiety i.e. if the combination of staff on a shift had little experience/knowledge. 3. Women recognised that certain occupation groups had more time and experience to support them i.e. nursery nurses on TCW, midwives on NICU. 4. The physical environment was an issue for respondents. For example: a. TCW privacy, or not, when expressing and feeding. b. In NICU screens used for expressing or feeding sometimes caused anxiety given that screens are also used when baby is poorly/undergoing a procedure. 5. In TCW, formula feed was linked to early discharge resulting in some experiencing subtle pressure to formula feed. 6. Community outreach team very supportive to some and women respondents felt they would have benefited from longer support. Six recommendations 1. Training needs to be consistent for all grades of staff and a whole day annually is preferred by healthcare professional respondents. 2. Release from service essential to ensure training is undertaken and given the high priority it deserves. 3. Different coloured screens for expressing/feeding AND for procedures would be beneficial and reduce stress for mothers and significant others. 4. Active recruitment of peer supporters with experience of having a baby in NICU. 5. Ensure continued support from peer supporters when moving from breastfeeding to formula feeding. 6. More information related to equipment available in the community on discharge i.e. hospital grade breast pumps

    Naturally Rehearsing Passwords

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    We introduce quantitative usability and security models to guide the design of password management schemes --- systematic strategies to help users create and remember multiple passwords. In the same way that security proofs in cryptography are based on complexity-theoretic assumptions (e.g., hardness of factoring and discrete logarithm), we quantify usability by introducing usability assumptions. In particular, password management relies on assumptions about human memory, e.g., that a user who follows a particular rehearsal schedule will successfully maintain the corresponding memory. These assumptions are informed by research in cognitive science and validated through empirical studies. Given rehearsal requirements and a user's visitation schedule for each account, we use the total number of extra rehearsals that the user would have to do to remember all of his passwords as a measure of the usability of the password scheme. Our usability model leads us to a key observation: password reuse benefits users not only by reducing the number of passwords that the user has to memorize, but more importantly by increasing the natural rehearsal rate for each password. We also present a security model which accounts for the complexity of password management with multiple accounts and associated threats, including online, offline, and plaintext password leak attacks. Observing that current password management schemes are either insecure or unusable, we present Shared Cues--- a new scheme in which the underlying secret is strategically shared across accounts to ensure that most rehearsal requirements are satisfied naturally while simultaneously providing strong security. The construction uses the Chinese Remainder Theorem to achieve these competing goals

    Genetic screening for gynecological cancer: where are we heading?

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    The landscape of cancer genetics in gynecological oncology is rapidly changing. The traditional family history-based approach has limitations and misses >50% mutation carriers. This is now being replaced by population-based approaches. The need for changing the clinical paradigm from family history-based to population-based BRCA1/BRCA2 testing in Ashkenazi Jews is supported by data that demonstrate population-based BRCA1/BRCA2 testing does not cause psychological harm and is cost effective. This article covers various genetic testing strategies for gynecological cancers, including population-based approaches, panel and direct-to-consumer testing as well as the need for innovative approaches to genetic counseling. Advances in genetic testing technology and computational analytics have facilitated an integrated systems medicine approach, providing increasing potential for population-based genetic testing, risk stratification, and cancer prevention. Genomic information along-with biological/computational tools will be used to deliver predictive, preventive, personalized and participatory (P4) and precision medicine in the future
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