1,141 research outputs found
Bewegen, maar waarheen? Dynamiek en onzekerheid in techniek en economie:Afscheidscollege van Prof. Dr. Ir. P.M.E.M. van der Grinten
Learner-Centered Nature Walks
Learner-Centered Nature Walks details the research of Heather van der Grinten in supplementing Junior Ranger Walks with a learner-centered mindset. The approach was intended to reflect her personal growth as a museum educator, demonstrate the viability of the Bank Street praxis of progressive education in an environmental education setting, and highlight potential growth for future Junior Ranger lesson-planning. The methodology involved experimenting with lesson plans, keeping a detailed reflection journal, and asking for voluntary feedback from peers, supervisors, and participants from June to September 2018. The samples of student work as shown in Appendix A and B were voluntarily given to van der Grinten to be used as part of her analysis. The research has found that asking for input as an initiation to an experience creates an immediate sense of engagement on the part of the participants. The research also concluded that inviting learners to create a visual artifact after a direct sensory experience provided an opportunity for reflection, group discussion, and an informal evaluation tool for the educator to monitor the program’s effectiveness. These findings support the ideal conclusion of a Junior Ranger Walk – an empowered youth who has the skill and desire to engage meaningfully in public lands
Experience in Optimising Fertility Outcomes in Men with Congenital Adrenal Hyperplasia due to 21 Hydroxylase Deficiency.
OBJECTIVE: Men with congenital adrenal hyperplasia (CAH) have impaired fertility. We aimed to assess fertility outcomes and the importance of hypogonadotropic hypogonadism, testicular failure and the presence of testicular adrenal rest tumours (TART). DESIGN: Retrospective analysis of men attending an adult CAH clinic in a tertiary centre. PATIENTS: Fifty men with CAH due to 21 hydroxylase deficiency were identified of whom 35 were salt-wasting and 15 were non-salt-wasting. MEASUREMENTS: Review of fertility history and parameters including luteinising hormone (LH), follicle stimulating hormone (FSH), androstenedione, 17-hydroxyprogesterone (17-OHP), semen analysis and the presence of testicular adrenal rest tissue (TART) on ultrasound. RESULTS: TART were detected by ultrasound in 21 (47%) and their presence was associated with an elevated FSH (p=0.01). Severe oligospermia was present in 11/23 (48%), and this was associated with an elevated FSH (p=0.02), suppressed LH (p5 x 10(6) per ml. Of those that desired fertility, 10/17 (59%) required treatment intensification, and 4 underwent in vitro fertilisation. Intensification resulted in a rise in median LH (0.6 to 4.3 IU/L; p=0.01). Live birth rate was 15/17 (88%) with a median (range) time to conception of 8(0-38) months. CONCLUSIONS: Suppressed LH is a marker for subfertility and is often reversible. Testicular failure is closely associated with TART formation. If TART are detected, sperm cryopreservation should be offered given the risk of progression to irreversible testicular failure. Male fertility in CAH can be improved by intensified treatment and assisted reproductive technology. This article is protected by copyright. All rights reserved
The development of Demand-driven care as a new governance concept
Demand-driven care is oriented towards an empowerment of patients/consumers through a redistribution of responsibilities and control among government, healthcare providers, insurers and patients. Different normative approaches can be distinguished in the discussion about the implementation and development of demand-driven care. The economic approach is aimed at competition and consumerism. The democratic approach of demand-driven care focuses on shared social responsibilities and accountability between the actors involved. In practice both approaches don’t get full meaning. The characteristics of sub-sectors within the healthcare system, institutional inertia and conflicting interests hamper a real shift form supply-oriented towards demand-oriented health care.Session 4: Public Managemen
Testicular adrenal rest tumors in a patient with untreated congenital adrenal hyperplasia
Testicular adrenal rest tumors (TARTs) are considered to be formed from aberrant adrenal tissue that has become hyperplastic because of elevated adrenocorticotropic hormone (ACTH) in male patients with congenital adrenal hyperplasia (CAH). A 6-year-old boy presented with testicular enlargement and pubic hair. He was diagnosed with CAH complicated by precocious puberty. However, he was not followed-up. At the age of 17, he visited the outpatient clinic because of testicular enlargement and short stature. His right and left testicles were 10×6 cm and 7.5×4.5 cm, respectively. His height was 155.1 cm (standard deviation score [SDS], -2.90). The diagnosis of CAH due to 21 hydroxylase deficiency was confirmed by mutation analysis of CYP21A2. Histological examination of the testes showed large, polygonal, eosinophilic cells with round nuclei and prominent nucleoli, which were suggestive of TARTs. He was treated with dexamethasone for 3 weeks and tumors regressed. Subsequently, dexamethasone was replaced by prednisolone and 9α-fludrocortisone; thereafter, the reduced testis size has been maintained
Design, implementation and evaluation of a distributed CDCL framework
The primary subject of this dissertation is practically solving instances of the Boolean satisfiability problem (SAT) that arise from industrial applications. The invention of the conflict-driven clause-learning (CDCL) algorithm led to enormous progress in this field. CDCL has been augmented with effective pre- and inprocessing techniques that boost its effectiveness. While a considerable amount of work has been done on applying shared-memory parallelism to enhance the performance of CDCL, solving SAT on distributed architectures is studied less thoroughly.
In this work, we develop a distributed, CDCL-based framework for SAT solving. This framework consists of three main components: 1. An implementation of the CDCL algorithm that we have written from scratch, 2. a
novel, parallel SAT algorithm that builds upon this CDCL implementation and 3. a collection of parallel simplification techniques for SAT instances. We call our resulting framework satUZK; our parallel solving algorithm is called the distributed divide-and-conquer (DDC) algorithm.
The DDC algorithm employs a parallel lookahead procedure to dynamically partition the search space. Load balancing is used to ensure that all computational resources are utilized during lookahead. This procedure results in a divide-and-conquer tree that is distributed over all processors. Individual threads are routed through this tree until they arrive at unsolved leaf vertices. Upon arrival, the lookahead procedure is invoked again or the leaf vertex is solved via CDCL. Several extensions to the DDC algorithm are proposed. These include clause sharing and a scheme to locally adjust the LBD score relative to the current search tree vertex. LBD is a measure for the usefulness of clauses that participate in a CDCL search. We evaluate our DDC algorithm empirically and benchmark it against the best distributed SAT algorithms. In this experiment, our DDC algorithm is faster than other distributed, state-of-the-art solvers and solves at least as many instances.
In addition to running a parallel algorithm for SAT solving we also consider parallel simplifcation. Here, we first develop a theoretical foundation that allows us to prove the correctness of parallel simplification techniques. Using this as a basis, we examine established simplification algorithms for their parallelizability. It turns out that several well-known simplification techniques can be parallelized efficiently. We provide parallel implementation of the techniques and test their effectiveness in empirical experiments. This evaluation finds several combinations of simplification techniques that can solve instances which could not be solved by the DDC algorithm alone
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