Placental MRI and its application to fetal intervention

Objective

Magnetic resonance imaging (MRI) of placental invasion has been part of clinical practice for many years. The possibility of being better able to assess placental vascularization and function using MRI has multiple potential applications. This review summarises up-to-date research on placental function using different MRI modalities.

Method

We discuss how combinations of these MRI techniques have much to contribute to fetal conditions amenable for therapy such as singletons at high risk for fetal growth restriction (FGR) and monochorionic twin pregnancies for planning surgery and counselling for selective growth restriction and transfusion conditions.

Results

The whole placenta can easily be visualized on MRI, with a clear boundary against the amniotic fluid, and a less clear placental-uterine boundary. Contrasts such as diffusion weighted imaging, relaxometry, blood oxygenation level dependent MRI and flow and metabolite measurement by dynamic contrast enhanced MRI, arterial spin labeling, or spectroscopic techniques are contributing to our wider understanding of placental function.

Conclusion

The future of placental MRI is exciting, with the increasing availability of multiple contrasts and new models that will boost the capability of MRI to measure oxygen saturation and placental exchange, enabling examination of placental function in complicated pregnancies.     

一种改进的多学习教与学优化算法

针对传统教与学算法在解决复杂多峰函数优化问题时,具有局部最优且搜索开发能力较差的缺点,提出了一种改进的多学习教与学优化算法,新算法为学员的每一维加入不同的教学因子,设计了基于学员均值比较的教师选择策略和向教师及学员学习的多学习策略。基于多个单峰和多峰函数的仿真结果表明,新算法跟传统的、改进的教与学算法相比,在稳定性、寻优精度和收敛速度方面更具优势。     

Developing the interaction matrix technique as a tool assessing the impact of traffic on air quality

This paper develops a technique which can be used as a preliminary tool for assessing air quality related to urban traffic. It combines a Geographic Information System (GIS) with an interaction matrix-type methodology based on a system analysis approach. The matrix identifies and quantifies interactions between all selected variables involved in a system as well as their interaction with the system as a whole. This matrix is used to determine the weightings to apply to spatial datasets within a GIS to develop a pollution vulnerability map. The focus of the paper is to introduce and assess a more versatile coding of the interaction matrix with respect to previously used coding. A case study is presented in which the modified interaction methodology is applied to data for a busy urban location. The resulting vulnerability map, in terms of pollution vulnerable hot spots, was compared to a pollution map derived from an advanced dispersion model. The interaction matrix technique with GIS can be used as a tool complementary to sophisticated numerical modelling and has potential as an analytical tool to evaluate multidisciplinary systems.     

Recovery in Naturally Dynamic Environments: A Case Study from the Sperrgebiet,Southern African Arid Succulent Karoo

Little is known about the process of vegetation recovery and associated time frames in the Succulent Karoo Biome of southern Africa. This study investigated the recovery of vegetation on sites impacted by mining (different types of dumps and mined areas) in the arid succulent karoo. The main aim of this study was to determine the state of recovery, time frames, successional stages, and the influence of environmental factors on recovery of coastal dune and sand plain plant communities. For this purpose, vegetation was recorded on some 121 sites throughout a coastal strip of approximately 100 × 3 km in Namibia’s restricted diamond area (Sperrgebiet). Using the species pool concept to derive vegetation reference sites and dominance-diversity curves, recovery of vegetation (measured in terms of species richness and cover) in these altered landscapes reached about 46% on the oldest, 51-year-old mine dumps. However, based on species richness, richness levels similar to the undisturbed reference sites were recorded after 30 years, following a logarithmic trend. Successional stages of natural recovery were indicated in this dynamic coastal environment and Cladoraphis cyperoides and Galenia fruticosa appear to be early successional species. Scaling up of studies to landscape level and developing a target community using the species pool concept are discussed as means to measure recovery in dynamic biological communities. On these altered, man-made landforms, the availability of seed may be the bottleneck to achieve vegetation cover comparable to undisturbed vegetation in the surrounding. Hence, restoration efforts should focus on this aspect.     

Devolving Residential Energy Efficiency Responsibility to Local Government: the case of HECA

Substantial improvements in residential energy efficiency are required if the UK is to meet its target of reducing CO 2 emissions by 20% between 1990 and 2010. The Home Energy Conservation Act 1995 (HECA) devolves much of the responsibility for this to local authorities, by requiring them to draw up strategies to increase energy efficiency in this sector by 30% in the next 10-15 years. While many authorities have responded positively to the Act, others are struggling, and 25% of HECA reports initially failed to meet the Act's statutory obligations. The Association for the Conservation of Energy (ACE) conducted research to identify barriers faced by local authorities in implementing HECA. They were found to include officers' lack of experience, their lack of time and a lack of support from elected members. Action must be taken to ensure that HECA achieves its potential. The authors suggest that the Act needs to be adequately supported by central legislation, and that devolution of responsibility must be accompanied by some devolution of finances. The authors also recommend that the Act could be used as an example for international replication.     

Career success and personal failure experiences and Type A behaviour

This study examines the relationship of Type A behaviour to career experiences associated with feelings of personal failure (Korman and Korman, 1980). Seventy-five managers completed the Jenkins Activity Survey, a widely used paper-and-pencil index of Type A behaviour, and measures of various career experiences. The data provided concurrent validation of the Korman's model and also showed Type A behaviour to be significantly related to career outcomes reflecting disappointment, alienation and personal failure. A case is made for the inclusion of Type A in career research. Implications for careerists and their organizations are offered.     

Identification of highly brominated analogues of Q1 in marine mammals

Three novel halogenated organic compounds (HOCs) have been identified in the blubber of marine mammals from coastal New England with the molecular formulae C(9)H(3)N(2)Br(6)Cl, C(9)H(3)N(2)Br(7), and C(9)H(4)N(2)Br(5)Cl. They were identified using high and low resolution gas chromatography mass spectrometry (GCMS) and appear to be highly brominated analogues of Q1, a heptachlorinated HOC suspected to be naturally produced. These compounds were found in Atlantic white sided dolphin (Lagenorhynchus acutus), bottlenose dolphin (Tursiops truncatus), common dolphin (Delphinus delphis), Risso's dolphin (Grampus griseus), harbor porpoise (Phocoena phocoena), beluga whale (Delphinapterus leucas), fin whale (Balaenoptera physalus), grey seal (Halichoerus grypus), harp seal (Phoca groenlandica) and a potential food source (Loligo pealei) with concentrations as high as 2.7 microg/g (lipid weight). The regiospecificity of C(9)H(3)N(2)Br(6)Cl is suggestive of a biogenic origin. Debromination of C(9)H(3)N(2)Br(6)Cl may be significant in the formation of C(9)H(4)N(2)Br(5)Cl.