2,645 research outputs found
Optimisation of hydroxyapatite (HAp) for orthopaedic application via the chemical precipitation technique
No full textHydroxyapatite, (HAp), Ca₁₀(PO₄)₆(OH)₂, is a naturally occurring mineral found in the inorganic component of human bone and enamel. The constituent elements of HAp are primarily calcium and phosphorous, with a stoichiometric calcium to phosphorous ratio of 1.667 capable of promoting intimate bone growth onto femoral implants. HAp is rendered a bioactive material since it has the ability to promote such growth with rapid fixation in what is also considered an osteoconductive process. The performance, lifespan and quality of the resultant biological coating in vivo is largely dependent on the coating morphology, phase composition, particle size and crystallinity of the powders pre-coating application. The present study aims to synthesise phase pure HAp powders via the wet chemical precipitation technique, in order to evaluate the critical process parameters and their effect (main and interaction) on controlling the final HAp powder characteristics, such as, phase composition, purity, crystallinity, crystallite size, lattice parameters, particle size and particle size distribution. These powders were synthesised with a view to satisfying regulatory requirements. These effects were quantified using Design of Experiments (Design Expert) to develop mathematical models, in terms of the chemical precipitation process parameters. HAp possessing optimum powder characteristics for orthopaedic application via the thermal plasma spray technique can therefore be prepared using the following chemical precipitation process parameters: reaction temperature 60ºC, ripening time 48h and stirring speed 1500rpm using high reagent concentrations. In the case of HAp synthesis at a lower reaction temperature, synthesis under a controlled environment (inert atmosphere) is desirable in order to achieve a high level of crystallinity: with an increase from 86.32% synthesised at 20ºC to 95.19% synthesised at 60ºC. The presence of an inert atmosphere appears less critical at synthesis under increased levels of reaction temperature. Ripening time and stirring speed significantly affect the final phase purity. An increase in both the ripening time (0.5 - 48h) and stirring speed (600 - 1500rpm) can result in an increase of purity by 77.74% (21.15 – 98.89%). Crystallite size, lattice parameters and mean particle size were also optimised within the research to find desired settings to achieve results suitable for FDA regulations
Presence of the Apolipoprotein E e4 allele is associated with the manifestation of Alzheimer dementia in adults with Down syndrome
No full textDeb S, Braganza J, Norton N, Williams H, Kehoe PG, Williams J, Owen M
U.S. real exchange rate fluctuations and relative price fluctuations
No full textThis paper studies the relation between the United States? bilateral real exchange rate and the associated bilateral relative price of nontraded goods for five of its most important trade relationships. Traditional theory attributes fluctuations in real exchange rates to changes in the relative price of nontraded goods. We find that this relation depends crucially on the choice of price series used to measure relative prices and on the choice of trade partner. The relation is stronger when we measure relative prices using producer prices rather than consumer prices. The relation is stronger the more important is the trade relationship between the United States and a trade partner. Even in cases where there is a strong relation between the real exchange rate and the relative price of nontraded goods, however, a large fraction of real exchange rate fluctuations is due to deviations from the law of one price for traded goods.Foreign exchange rates ; Prices ; International trade ; International finance ; Monetary policy
Birth size and physical activity in a cohort of Indian children aged 6-10 years
No full textThere is evidence of a reduction in children’s physical activity in India in the last decade. Our objective was to assess whether size and body composition at birth are associated with physical activity in school-aged children. Children from a prospective observational cohort study born in Mysore, South India between 1997 and 1998 (n5663) had neonatal anthropometric measurements made within 72 h of delivery [weight, mid-upper arm circumference (MUAC), chest, abdomen and head circumference, crown–heel, crown–buttock and leg length, triceps and subscapular skinfolds]. At 6–10 years, children (n5449) were asked to wear AM7164 or GT1M Actigraph accelerometers for 7 days. Body composition was measured within 6 months of activity monitoring. Arm muscle area at birth and time of activity monitoring was calculated from MUAC and skinfold measurements. Activity outcome measures were: mean accelerometer counts per minute (cpm); counts per day and proportion of time spent in moderate and vigorous activity. The mean (S.D.) number of days with >500 min of recorded accelerometer data was 7.0 (1.1). Linear regression models showed no significant associations between any of the neonatal anthropometric measures and the activity variables. Body fat percentage at 7.5 years was negatively associated with all activity variables (B524.69, CI: 27.31, 22.07 for mean cpm). In conclusion, this study showed no associations between body size and skinfold thickness at birth and objectively measured physical activityin childhood
Reporting of participant compliance in randomized controlled trials of nutrition supplements during pregnancy
No full textRandomized controlled trials (RCT) are widely considered to be the gold standard for demonstrating intervention effects. Adequacy of reporting of participant compliance in RCTs affects the interpretation of study results. Our aims were two-fold: first, to assess the adequacy of reporting of participant compliance in RCTs investigating the effect of maternal nutritional supplements on infant outcomes; and second, to examine authors' adherence to the Consolidated Standards of Reporting Trials (CONSORT) guidelines on participant flow. Papers reporting trials of nutritional supplementation during pregnancy, and published after revision of the CONSORT recommendations, were identified using a search of medical databases. Two researchers systematically reviewed the papers to assess the reporting of participant compliance according to specified criteria, and the presentation of participant flow data recommended in the CONSORT guidelines. The literature search identified 58 papers. Almost a third (n = 18) did not describe how participant compliance was assessed. Nearly half of the papers (n = 27) failed to report participant compliance numerically (absolute numbers or percentage) and differences in compliance data between treatment arms were not reported in 52% of papers (n = 28). The majority (83%) gave no information on whether the study protocol included any researcher input aimed at maximizing compliance. In addition to inadequate reporting of compliance, two of the CONSORT requirements (eligibility criteria and numbers discontinuing the intervention) were inadequately reported in 69% and 60% of papers, respectively. We conclude that participant compliance in nutrition trials is frequently inadequately reported. 'False negative' results from RCTs with poor compliance could wrongly influence policy and inhibit further research concerned with nutritional supplementation for women of child-bearing age. We suggest that changes to the CONSORT guidelines may improve RCT reporting
What can we learn from the current crisis in Argentina?
No full textCurrently, Argentina is experiencing what the government describes as a "great depression." Using the "Great Depressions" methodology developed by Cole and Ohanian (1999) and Kehoe and Prescott (2002), we find that the primary determinants of both the boom in Argentina in the 1990s and the subsequent depression were changes in productivity, rather than changes in factor inputs. The timing of events links the boom to the currency-board-like Convertibility Plan and the crisis to its collapse. To gain credibility, the Argentine government took measures to make abandoning the plan more costly. Because the government was unable to enforce fiscal discipline, however, these increased costs failed to make the plan more credible and instead made the crisis far worse when it failed.Argentina ; Monetary policy - Argentina
Survival Trends for Uterine Sarcomas from a Tertiary Center: The Oxford Experience
No full text: Uterine sarcomas are rare and aggressive gynecological malignancies. We evaluated the epidemiology, treatment outcomes and survival rates in uterine sarcoma patients managed in our institute. The medical records of women with histology proven uterine sarcoma, including leiomyosarcoma (LMS), adenosarcoma (ADS), and endometrial stromal sarcoma (ESS), treated at our institution from February 2010 to February 2022, were analyzed. In total, 41 patients were identified. In detail, LMS, ADS, and high-grade and low-grade ESS were identified, respectively, in 60.9%, 19.5%, 12.1%, and 7.3% of the cases. The majority of women affected by LMS (72%) underwent primary surgery and 40% of them also received adjuvant chemotherapy. A surgical approach was the preferred mode of treatment in 83% of the recurrences. The median OS (overall survival), DFS (disease free survival), and PFS (progression free survival) for the LMS group were 25, 44.5, and 8 months, respectively. The 5-year survival rates for LMS, ADS, and ESS groups were 30.5%, 100% and 37.5%, respectively. The 5-year survival for LMS was found to be significantly worse than for other histology types (p = 0.016). Our study provides valuable data for the evaluation of treatment strategies and survival trends among these rare cancers. The management and follow-up planning of each subtype requires a thorough patient-focused multidisciplinary discussion
OPTIMAL FISCAL POLICY IN A BUSINESS CYCLE MODEL: ALTERNATIVE IDENTIFICATIONS OF THE OPTIMAL EXPOST CAPITAL INCOME TAX RATES
No full textThis paper deals with the indeterminacy of optimal fiscal policy treated by Zhu (1992) and Chari, Christiano and Kehoe (1994). These authors identify the optimal fiscal policy restricting the debt return to be uncontingent to the state of nature. In this paper we use other kind of restrictions in order to identify the optimal fiscal policy. Using the solution method proposed by Sims (1998), we can select an equilibrium by enforcing a stable path for the bonds allocation, to identify all the fiscal policy variables contingent to the state of nature. We also use a decomposition of the expectational terms that allow us to obtain the ex-ante capital income tax rate in order to be compared with the ex-post (contingent) tax rate. We can demonstrate that the risk aversion changes the relationship between the expectational errors of the private agents and the sources of fluctuations. The numerical simulation provides some different results: the optimal tax rate on capital incom e is constant, instead of the very volatile tax rate obtained by Chari, Christiano and Kehoe (1994). This property remains unaltered when we use alternative restrictions (exogenous debt path and exogenous expectational errors) to identify the contingent optimal fiscal policy.
Comparison of survival outcome of patients with primary peritoneal and fallopiantube carcinoma treated with neoadjuvant chemotherapy versus primary debulking surgery
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