Null controllability of the heat equation as singular limit of the exact controllability of dissipative wave equation under the Bardos-Lebeau-Rauch geometric control condition

AbstractWe extend the result of the null controllability property of the heat equation, obtained as limit, when ϵ tends to zero, of the exact controllability of a singularly perturbed damped wave equation depending on a parameter ϵ > 0, described in [1], to bounded domains which satisfy the Bardos-Lebeau-Rauch geometric control condition [2]. We add to the method of Lopez, Zhang and Zuazua in [1] an explicit in ϵ > 0 observability estimate for the singularly perturbed damped wave equation under the Bardos-Lebeau-Rauch geometric control condition. Here the geometric conditions are more optimal than in [1] and the proof is simpler than in [1]. Instead of using global Carleman inequalities as in [1], we apply an integral representation formula

Applying the Fuzzy Analytic Network Process to Establish the Relative Importance of Knowledge Sharing Barriers

Knowledge sharing (KS) is the key to creativity and innovation in any organizations. Overcoming the KS barriers has created new challenges for designing in dynamic and complex environment. There may be interrelations and interdependences among the barriers. The purpose of this paper is to present a review of literature of KS barriers and impute the relative importance of them through the fuzzy analytic network process that is a generalization of the analytical hierarchy process (AHP). It helps to prioritize the barriers to find ways to remove them to facilitate KS. The study begins with a brief description of KS barriers and the most critical ones. The FANP and its role in identifying the relative importance of KS barriers are explained. The paper, then, proposes the model for research and expected outcomes. The study suggests that the use of the FANP is appropriate to impute the relative importance of KS barriers which are intertwined and interdependent. Implications and future research are also propose

Adjusting Overall Survival Estimates after Treatment Switching: a Case Study in Metastatic Castration-Resistant Prostate Cancer

Background If patients in oncology trials receive subsequent therapy, standard intention-to-treat (ITT) analyses may inaccurately estimate the overall survival (OS) effect of the investigational product. In this context, a post-hoc analysis of the phase 3 PREVAIL study was performed with the aim to compare enzalutamide with placebo in terms of OS, adjusting for potential confounding from switching to antineoplastic therapies that are not part of standard metastatic castration-resistant prostate cancer (mCRPC) treatment pathways in some jurisdictions. Methods The PREVAIL study, which included 1717 chemotherapy-naïve men with mCRPC randomized to treatment with enzalutamide 160 mg/day or placebo, was stopped after a planned interim survival analysis revealed a benefit in favor of enzalutamide. Data from this cutoff point were confounded by switching from both arms and so were evaluated in terms of OS using two switching adjustment methods: the two-stage accelerated failure time model (two-stage method) and inverse probability of censoring weights (IPCW). Results Following adjustment for switching to nonstandard antineoplastic therapies by 14.8 (129/872 patients) and 21.3% (180/845 patients) of patients initially randomized to enzalutamide and placebo, respectively, the two-stage and IPCW methods both resulted in numerical reductions in the hazard ratio (HR) for OS [HR 0.66, 95% confidence interval (CI) 0.57–0.81 and HR 0.63, 95% CI 0.52–0.75, respectively] for enzalutamide compared to placebo versus the unadjusted ITT analysis (HR 0.71, 95% CI 0.60–0.84). These results suggest a slightly greater effect of enzalutamide on OS than originally reported. Conclusion In the PREVAIL study, switching to nonstandard antineoplastic mCRPC therapies resulted in the ITT analysis of primary data underestimating the benefit of enzalutamide on OS

Foreign currency options: An empirical analysis

The objective of this thesis is to study the pricing of foreign currency options by using transaction data. It is to investigate empirically the hypothesis of option markets efficiency on the Philadelphia Stock Exchange (PHLX) between August 1987 and October 1994 It uses daily trade-to-trade transaction for the studies on (1) European put-call parity, (2) American put-call pricing relationship, (3) the early- exercise premium of the American options, (4) the volatility smile and risk-neutral distribution of the American options, (5) models for predicting option prices with yesterday’s market volatility smile, and (6) the difference between volatility smiles on the over-the-counter (OTC) and PHLX markets. The first three tests employ both non-transaction-cost and full-transaction-cost scenarios. The put-call party does not hold and the results provide evidence of arbitrage profit opportunities for investors (i.e., an investor might be able to earn risk-free profit). It is not possible to reject (with confidence) the hypothesis that PHLX currency option market is inefficient. Deutsche Mark options are the most heavily traded options on the PHLX and they have therefore been used for sections (4) to (6). The fourth test confirms that the volatility smiles of calls and puts are asymmetrical, both calls and puts are skewed from the right to the left. The smile has an average positive (+1.2%) volatility skewness. The calls also have higher volatility than the puts in general. However, the OTC options in section (6) give a different result. The OTC and exchange markets have different volatility smiles and the OTC options’ volatility smile is negatively skewed. Although the observed options’ volatilities have a smile, the predicting of tomorrow’s option prices in the section (5) with today’s market volatility smile gives larger errors than assuming no smile at all. The PHLX options in section (6) have an irregular wave-shaped volatility smile across strike prices and observed period. It reflects that prediction of option’s volatility required a more powerful deterministic volatility function. In section (6), PHLX options have higher volatility than OTC options. Moreover, both PHLX and OTC markets have different volatility skewness, it allows investors with low transaction costs to obtain risk-free arbitrages. In summary, the six tests have showed that the options' markets are not perfectly efficient

Development of a new biochemical test to diagnose and monitor neuroblastoma in Vietnam: Homovanillic and vanillylmandelic acid by gas chromatography-mass spectrometry

Objectives<br> The aim of this study was to develop an accurate robust testing method to simultaneously measure urine levels of HVA and VMA using gas chromatography mass spectrometry (GCMS) and to establish age-specific reference intervals of HVA and VMA in random urines for Vietnamese children.<p></p>Design and methods<br> The assay for urinary HVA and VMA was developed based on a classical urinary organic acid profiling method. Briefly, this incorporated 3-phenyl butyric acid as the internal standard and liquid–liquid extraction with ethyl acetate followed by derivatization with BSTFA. The Agilent 7890A GC and 5975C Mass Selective Detector in single ion monitoring mode was used for analysis.<p></p> Reference intervals were developed from random urine samples collected from 634 disease free Vietnamese children and compared to 50 known neuroblastoma patient samples. Results were reported relative to creatinine concentration. Age related 95% reference intervals for urinary HVA and VMA were estimated from sample quantiles. The analytes (expressed as analyte/creatinine ratios) diagnostic values were determined by calculating the related sensitivity, specificity and likelihood ratios.<p></p> Results<br> HVA and VMA were linear to at least 193 and 221 μmol/L, respectively. The limit of quantitation for both analytes was 0.9 μmol/L. Using the bi-level control (n = 15), the within-batch coefficients of variations (CVs) were less than 3% for both analytes across the assay range. The between-batch CVs (n = 20 over three months), were 3.6% at 11 μmol/L and 2.1% at 88 μmol/L for HVA, 6.6% at 18.2 μmol/L and 2.6% at 90.6 μmol/L for VMA.<p></p> Vietnamese age related reference intervals were established for urinary HVA and VMA per creatinine. HVA for children < 6 months (n = 91) was 5.3–37.0 μmol/mmol; 6 months to < 1 year (n = 141) was 2.7–27.7 μmol/mmol; 1 to 5 years (n = 139) was 3.4–17.9 μmol/mmol; 6 to 10 years (n = 136) was 2.7–8.8 μmol/mmol; and 11 to 15 years (n = 127) was 1.1–9.4 μmol/mmol. VMA for children < 6 months was 1.8–12.2 μmol/mmol; 6 months to < 1 year was 1.5–9.3 μmol/mmol; 1 to 5 years was 1.9–7.8 μmol/mmol; 6 to 10 years was 1.6–5.1 μmol/mmol; and 11 to 15 years was < 0.9–6.3 μmol/mmol.<p></p> Conclusions<br> A robust testing method for simultaneous quantitation of urinary HVA and VMA by GCMS was developed. This method is accurate, precise and fit for its clinical purpose and suitable for developing countries. Age-related reference intervals of urinary HVA and VMA were established for Vietnamese children and the intervals declined progressively with increasing age for each analyte

Reconstructing initial data using observers: error analysis of the semi-discrete and fully discrete approximations

A new iterative algorithm for solving initial data inverse problems from partial observations has been recently proposed in Ramdani et al. (Automatica 46(10), 1616-1625, 2010 ). Based on the concept of observers (also called Luenberger observers), this algorithm covers a large class of abstract evolution PDE's. In this paper, we are concerned with the convergence analysis of this algorithm. More precisely, we provide a complete numerical analysis for semi-discrete (in space) and fully discrete approximations derived using finite elements in space and an implicit Euler method in time. The analysis is carried out for abstract Schrödinger and wave conservative systems with bounded observation (locally distributed)

Shigella flexneri serotype 1c derived from serotype 1a by acquisition of gtrIC gene cluster via a bacteriophage

BACKGROUND: Shigella spp. are the primary causative agents of bacillary dysentery. Since its emergence in the late 1980s, the S. flexneri serotype 1c remains poorly understood, particularly with regard to its origin and genetic evolution. This article provides a molecular insight into this novel serotype and the gtrIC gene cluster that determines its unique immune recognition. RESULTS: A PCR of the gtrIC cluster showed that serotype 1c isolates from different geographical origins were genetically conserved. An analysis of sequences flanking the gtrIC cluster revealed remnants of a prophage genome, in particular integrase and tRNAPro genes. Meanwhile, Southern blot analyses on serotype 1c, 1a and 1b strains indicated that all the tested serotype 1c strains may have had a common origin that has since remained distinct from the closely related 1a and 1b serotypes. The identification of prophage genes upstream of the gtrIC cluster is consistent with the notion of bacteriophage-mediated integration of the gtrIC cluster into a pre-existing serotype. CONCLUSIONS: This is the first study to show that serotype 1c isolates from different geographical origins share an identical pattern of genetic arrangement, suggesting that serotype 1c strains may have originated from a single parental strain. Analysis of the sequence around the gtrIC cluster revealed a new site for the integration of the serotype converting phages of S. flexneri. Understanding the origin of new pathogenic serotypes and the molecular basis of serotype conversion in S. flexneri would provide information for developing cross-reactive Shigella vaccines

Clinical guidelines for caring for women with COVID-19 during pregnancy, childbirth and the immediate postpartum period.

BACKGROUND:The spread of the novel coronavirus (COVID-19) was declared a pandemic by the World Health Organization on 11th March 2020. Since then there has been a rapid rise in development of maternal and perinatal health guidelines related to COVID-19. The aim of this project was to develop a database of Australian and international recommendations relating to antenatal, intrapartum and postpartum care of women during the COVID-19 pandemic, in order to identify inconsistencies in clinical guidance. METHODS:We conducted weekly web searches from 30th March to 15th May 2020 to identify recommendations pertaining to the care of women during pregnancy, labour and postpartum period from national or international professional societies, specialist colleges, Ministries of Health, Australian state and territory governments, and international guideline development organisations. Individual recommendations were extracted and classified according to intervention type, time period, and patient population. Findings were reported using descriptive analysis, with areas of consensus and non-consensus identified. RESULTS:We identified 81 guidelines from 48 different organisations. Generally, there was high consensus across guidelines for specific interventions. However, variable guidance was identified on the use of nitrous oxide during labour, administration of antenatal corticosteroids, neonatal isolation after birth, labour and birth companions, and the use of disease modifying agents for treating COVID-19. CONCLUSION:Discrepancies between different guideline development organisations creates challenges for maternity care clinicians during the COVID-19 pandemic. Collating recommendations and keeping up-to-date with the latest guidance can help clinicians provide the best possible care to pregnant women and their babies