Bin Teng

Bio: Bin Teng is an academic researcher from Dalian University of Technology. The author has contributed to research in topics: Boundary element method & Free surface. The author has an hindex of 35, co-authored 174 publications receiving 3539 citations. Previous affiliations of Bin Teng include Genetics and IVF Institute & University of Oxford.

Automated Solution of Differential Equations by the Finite Element Method: The FEniCS Book

Abstract: This book is a tutorial written by researchers and developers behind the FEniCS Project and explores an advanced, expressive approach to the development of mathematical software. The presentation spans mathematical background, software design and the use of FEniCS in applications. Theoretical aspects are complemented with computer code which is available as free/open source software. The book begins with a special introductory tutorial for beginners. Followingare chapters in Part I addressing fundamental aspects of the approach to automating the creation of finite element solvers. Chapters in Part II address the design and implementation of the FEnicS software. Chapters in Part III present the application of FEniCS to a wide range of applications, including fluid flow, solid mechanics, electromagnetics and geophysics.

A review of wave energy converter technology

Abstract: Ocean waves are a huge, largely untapped energy resource, and the potential for extracting energy from waves is considerable. Research in this area is driven by the need to meet renewable energy targets, but is relatively immature compared to other renewable energy technologies. This review introduces the general status of wave energy and evaluates the device types that represent current wave energy converter (WEC) technology, particularly focusing on work being undertaken within the United Kingdom. The possible power take-off systems are identified, followed by a consideration of some of the control strategies to enhance the efficiency of point absorber-type WECs. There is a lack of convergence on the best method of extracting energy from the waves and, although previous innovation has generally focused on the concept and design of the primary interface, questions arise concerning how best to optimize the powertrain. This article concludes with some suggestions of future developments.

Oocyte, embryo and blastocyst cryopreservation in ART: systematic review and meta-analysis comparing slow-freezing versus vitrification to produce evidence for the development of global guidance

Abstract: BACKGROUND Successful cryopreservation of oocytes and embryos is essential not only to maximize the safety and efficacy of ovarian stimulation cycles in an IVF treatment, but also to enable fertility preservation. Two cryopreservation methods are routinely used: slow-freezing or vitrification. Slow-freezing allows for freezing to occur at a sufficiently slow rate to permit adequate cellular dehydration while minimizing intracellular ice formation. Vitrification allows the solidification of the cell(s) and of the extracellular milieu into a glass-like state without the formation of ice. OBJECTIVE AND RATIONALE The objective of our study was to provide a systematic review and meta-analysis of clinical outcomes following slow-freezing/thawing versus vitrification/warming of oocytes and embryos and to inform the development of World Health Organization guidance on the most effective cryopreservation method. SEARCH METHODS A Medline search was performed from 1966 to 1 August 2016 using the following search terms: (Oocyte(s) [tiab] OR (Pronuclear[tiab] OR Embryo[tiab] OR Blastocyst[tiab]) AND (vitrification[tiab] OR freezing[tiab] OR freeze[tiab]) AND (pregnancy[tiab] OR birth[tiab] OR clinical[tiab]). Queries were limited to those involving humans. RCTs and cohort studies that were published in full-length were considered eligible. Each reference was reviewed for relevance and only primary evidence and relevant articles from the bibliographies of included articles were considered. References were included if they reported cryosurvival rate, clinical pregnancy rate (CPR), live-birth rate (LBR) or delivery rate for slow-frozen or vitrified human oocytes or embryos. A meta-analysis was performed using a random effects model to calculate relative risk ratios (RR) and 95% CI. OUTCOMES One RCT study comparing slow-freezing versus vitrification of oocytes was included. Vitrification was associated with increased ongoing CPR per cycle (RR = 2.81, 95% CI: 1.05-7.51; P = 0.039; 48 and 30 cycles, respectively, per transfer (RR = 1.81, 95% CI 0.71-4.67; P = 0.214; 47 and 19 transfers) and per warmed/thawed oocyte (RR = 1.14, 95% CI: 1.02-1.28; P = 0.018; 260 and 238 oocytes). One RCT comparing vitrification versus fresh oocytes was analysed. In vitrification and fresh cycles, respectively, no evidence for a difference in ongoing CPR per randomized woman (RR = 1.03, 95% CI: 0.87-1.21; P = 0.744, 300 women in each group), per cycle (RR = 1.01, 95% CI: 0.86-1.18; P = 0.934; 267 versus 259 cycles) and per oocyte utilized (RR = 1.02, 95% CI: 0.82-1.26; P = 0.873; 3286 versus 3185 oocytes) was reported. Findings were consistent with relevant cohort studies. Of the seven RCTs on embryo cryopreservation identified, three met the inclusion criteria (638 warming/thawing cycles at cleavage and blastocyst stage), none of which involved pronuclear-stage embryos. A higher CPR per cycle was noted with embryo vitrification compared with slow-freezing, though this was of borderline statistical significance (RR = 1.89, 95% CI: 1.00-3.59; P = 0.051; three RCTs; I2 = 71.9%). LBR per cycle was reported by one RCT performed with cleavage-stage embryos and was higher for vitrification (RR = 2.28; 95% CI: 1.17-4.44; P = 0.016; 216 cycles; one RCT). A secondary analysis was performed focusing on embryo cryosurvival rate. Pooled data from seven RCTs (3615 embryos) revealed a significant improvement in embryo cryosurvival following vitrification as compared with slow-freezing (RR = 1.59, 95% CI: 1.30-1.93; P < 0.001; I2 = 93%). WIDER IMPLICATIONS Data from available RCTs suggest that vitrification/warming is superior to slow-freezing/thawing with regard to clinical outcomes (low quality of the evidence) and cryosurvival rates (moderate quality of the evidence) for oocytes, cleavage-stage embryos and blastocysts. The results were confirmed by cohort studies. The improvements obtained with the introduction of vitrification have several important clinical implications in ART. Based on this evidence, in particular regarding cryosurvival rates, laboratories that continue to use slow-freezing should consider transitioning to the use of vitrification for cryopreservation.

Is frozen embryo transfer better for mothers and babies? Can cumulative meta-analysis provide a definitive answer?

Abstract: BACKGROUND Initial observational studies and a systematic review published 5 years ago have suggested that obstetric and perinatal outcomes are better in offspring conceived following frozen rather than fresh embryo transfers, with reduced risks of preterm birth, small for gestational age, low birth weight and pre-eclampsia. More recent primary studies are beginning to challenge some of these findings. We therefore conducted an updated systematic review and cumulative meta-analysis to examine if these results have remained consistent over time. OBJECTIVE AND RATIONALE The aim of this study was to perform a systematic review and cumulative meta-analysis (trend with time) of obstetric and perinatal complications in singleton pregnancies following the transfer of frozen thawed and fresh embryos generated through in-vitro fertilisation. SEARCH METHODS Data Sources from Medline, EMBASE, Cochrane Central Register of Clinical Trials DARE and CINAHL (1984–2016) were searched using appropriate key words. Observational and randomised studies comparing obstetric and perinatal outcomes in singleton pregnancies conceived through IVF using either fresh or frozen thawed embryos. Two independent reviewers extracted data in 2 × 2 tables and assessed the methodological quality of the relevant studies using CASP scoring. Both aggregated as well as cumulative meta-analysis was done using STATA. OUTCOMES Twenty-six studies met the inclusion criteria. Singleton babies conceived from frozen thawed embryos were at lower relative risk (RR) of preterm delivery (0.90; 95% CI 0.84–0.97) low birth weight (0.72; 95% CI 0.67–0.77) and small for gestational age (0.61; 95% CI 0.56–0.67) compared to those conceived from fresh embryo transfers, but faced an increased risk (RR) of hypertensive disorders of pregnancy (1.29; 95% CI 1.07–1.56) large for gestational age (1.54; 95% CI 1.48–1.61) and high birth weight (1.85; 95% CI 1.46–2.33). There was no difference in the risk of congenital anomalies and perinatal mortality between the two groups. The direction and magnitude of effect for these outcomes have remained virtually unchanged over time while the degree of precision has improved with the addition of data from newer studies. WIDER IMPLICATIONS The results of this cumulative meta-analysis confirm that the decreased risks of small for gestational age, low birth weight and preterm delivery and increased risks of large for gestational age and high birth weight associated with pregnancies conceived from frozen embryos have been consistent in terms of direction and magnitude of effect over several years, with increasing precision around the point estimates. Replication in a number of different populations has provided external validity for the results, for outcomes of birth weight and preterm delivery. Meanwhile, caution should be exercised about embarking on a policy of electively freezing all embryos in IVF as there are increased risks for large for gestational age babies and hypertensive disorders of pregnancy. Therefore, elective freezing should ideally be undertaken in specific cases such as ovarian hyperstimulation syndrome, fertility preservation or in the context of randomised trials.