197 research outputs found

    Statistical modelling of summary values leads to accurate Approximate Bayesian Computations

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    Approximate Bayesian Computation (ABC) methods rely on asymptotic arguments, implying that parameter inference can be systematically biased even when sufficient statistics are available. We propose to construct the ABC accept/reject step from decision theoretic arguments on a suitable auxiliary space. This framework, referred to as ABC*, fully specifies which test statistics to use, how to combine them, how to set the tolerances and how long to simulate in order to obtain accuracy properties on the auxiliary space. Akin to maximum-likelihood indirect inference, regularity conditions establish when the ABC* approximation to the posterior density is accurate on the original parameter space in terms of the Kullback-Leibler divergence and the maximum a posteriori point estimate. Fundamentally, escaping asymptotic arguments requires knowledge of the distribution of test statistics, which we obtain through modelling the distribution of summary values, data points on a summary level. Synthetic examples and an application to time series data of influenza A (H3N2) infections in the Netherlands illustrate ABC* in action.Comment: Videos can be played with Acrobat Reader. Manuscript under review and not accepte

    The rat androgen receptor gene promoter

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    The androgen receptor (AR) is activated upon binding of testosterone or dihydrotestosterone and exerts regulatory effects on gene expression in androgen target cells. To study transcriptional regulation of the rat AR gene itself, the 5' genomic region of this gene was cloned from a genomic library and the promoter was identified. S1-nuclease protection analysis showed two major transcription start sites, located between 1010 and 1023 bp upstream from the translation initiation codon. The area surrounding these start sites was cloned in both orientations in a CAT reporter plasmid. Upon transfection of the constructs into COS cells, part of the promoter stimulated transcription in an orientation-independent manner, but the full promoter showed a higher and unidirectional activity. In the promoter/reporter gene constructs, transcription initiated from the same positions as in the native gene. Sequence analysis showed that the promoter of the rat AR gene lacks typical TATA and CCAAT box elements, but one SP1 site is located at about 60 bp upstream from the major start site of transcription. Other possible promoter elements are TGTYCT sequences at positions -174 to -179, -434 to -439., -466 to -471, and -500 to -505, resembling half-sites of the glucocorticoid-responsive element (GRE). Furthermore, a homopurine stretch containing a total of 8 GGGGA elements and similar to sequences that are present in several other GC-rich promoters, is located between -89 and -146 bp upstream from the major start site of transcriptio

    Report Topsector Potato India and Ethiopia 2015/16

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    The Agricultural Counsellor of the Netherlands Embassy in Delhi initiated a BOCI project ‘Overview of the potato chain in India’ in early 2011. In September 2012 this initiative has been adopted by the Dutch and Indian stakeholders and the Pubic Private Partnership (PPS) was established to facilitate the intensification of collaboration between Dutch and Indian stakeholders of the potato chain. A team of Wageningen UR researchers was commissioned to carry out this project. In 2011, the team collected information from reports, personal files, internet and some Dutch companies and reported the information in “An overview of the potato sector in India and prospects of Indo & Dutch cooperation”. The team also participated in the Netherlands Trade mission to India (5 & 11 June 2011) and visited the Central Potato Research Institute at Shimla. Furthermore jointly with the Agricultural Counsellor we organized a potato seminar to present our findings on 5 October 2011 in Delhi. Major potato stakeholders both from India and from the Netherlands attended the seminar; total number of participants was about 60 persons. In 2012, 2013, 2014, 2015 and 2016 the team carried out different tasks such as presenting information on various subjects of the Dutch and Indian potato chain to exchange knowledge. In addition, several identified subjects were investigated. All actions and activities aimed to facilitate collaboration between Dutch and Indian stakeholders. Visits to different locations of India accompanied by Dutch stakeholders, meetings with experts of the Indian potato production chain both stakeholders and researchers, and topics such as skin curing and chemical haulm killing, reduce storage losses and the establishment of the Centres of Excellence (CoE) in Punjab (Jalandhar) and Uttar Pradesh, and the Centre of Potato Expertise (COPE) at Ludhiana (Punjab) were successfully accomplished

    Two Cases of Cardiac Arteriovenous Malformation Complicated by a Local Angioproliferative Process

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    Vascular malformations of the heart are extremely rare with only a few cases of the arteriovenous type of vascular malformation (AVM) reported. We investigated the pathology of two additional cases, which were complicated by the occurrence of a local vasoproliferative response of immature but benign vessels. We suppose that the mass forming effect of this vasoproliferative response, which has also been reported recently as a complication of congenital AVM elsewhere in the body, has significantly contributed to the onset of symptoms and ultimate death of both patients

    Impact of the Introduction of Calcimimetics on Timing of Parathyroidectomy in Secondary and Tertiary Hyperparathyroidism

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    Hyperparathyroidism (HPT), both secondary and tertiary, is common in patients with end-stage renal disease, and is associated with severe bone disorders, cardiovascular complications, and increased mortality. Since the introduction of calcimimetics in 2004, treatment of HPT has shifted from surgery to predominantly medical therapy. The aim of this study was to evaluate the impact of this change of management on the HPT patient population before undergoing (sub-)total parathyroidectomy (PTx). Overall, 119 patients with secondary or tertiary HPT undergoing PTx were included in a retrospective, single-center cohort. Group A, who underwent PTx before January 2005, was compared with group B, who underwent PTx after January 2005. Patient characteristics, time interval between HPT diagnosis and PTx, and postoperative complications were compared. Group A comprised 70 (58.8 %) patients and group B comprised 49 (41.2 %) patients. The median interval between HPT diagnosis and PTx was 27 (interquartile range [IQR] 12.5-48.0) and 49 (IQR 21.0-75.0) months for group A and B, respectively (p = 0.007). Baseline characteristics were similar among both groups. The median preoperative serum parathyroid hormone (PTH) level was 936 pg/mL (IQR 600-1273) for group A versus 1091 pg/mL (IQR 482-1373) for group B (p = 0.38). PTx resulted in a dramatic PTH reduction (less than twofold the upper limit: A, 80.0 %; B, 85.4 %), and postoperative complication rates were low in both groups (A: 7.8 %; B: 10.2 %) [p = 0.66]. The introduction of calcimimetics in 2004 is associated with a significant 2-year delay of surgery with continuously elevated preoperative PTH levels, while parathyroid surgery, even in a fragile population, is considered a safe and effective procedure
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