Subsistence agriculture and child growth in Papua New Guinea

Spatial statistical analyses of child anthropometric data were undertaken to assess the influence of systems of subsistence agriculture, in terms of staple foods and cash crops cultivated, on patterns of child growth in Papua New Guinea. These agricultural data explained between a quarter and half of the geographical variation in anthropometric growth indicators. Accounting for differences in altitude, relief and rainfall patterns, though explaining additional geographical variation, did not improve the predictions. Child growth was better in agriculture systems with cassava and sweet potato as staple crops, but worse in systems where banana, sago and taro were staple crops. Both the cultivation of all major cash crops, and sales of fish and food crops improved child growth. More intensive agricultural systems were associated with larger children indicating that the nutritional status of children benefited from intensification as well as from the introduction of cash crops into traditional subsistence systems.     

Wind-borne insects mediate directional pollen transfer between desert fig trees 160 kilometers apart

The question of how far pollen can move between plants has implications for topics as diverse as habitat fragmentation, conservation management, and the containment of genetically modified crops. The monoecious African fig tree Ficus sycomorus L. relies on the small, short-lived, night-flying, host-specific fig wasp Ceratosolen arabicus Mayr for pollination. We used microsatellite markers to characterize a geographically isolated riparian population of F. sycomorus growing along the Ugab River in the Namib Desert, Namibia, together with paternity analysis of seedlings from known mothers, to map pollen movement within this population. In this way we tracked insect movements between individually recognizable trees by means of their pollen cargo and documented the movement of C. arabicus between known trees separated by more than 160 km, with a mean distance for confirmed successful pollination events of 88.6 km. The predominant observed movement of pollinators was in a westerly direction, toward the sea, reflecting seasonal nighttime wind direction and the wind-borne dispersal of fig wasps. Our results suggest the existence of an extensive panmictic population of trees that are well suited to overcome the effects of geographical isolation.     

A multivariate hypothesis testing framework for tissue clustering and classification of DTI data

The primary aim of this work is to propose and investigate the effectiveness of a novel unsupervised tissue clustering and classification algorithm for diffusion tensor MRI (DTI) data. The proposed algorithm utilizes information about the degree of homogeneity of the distribution of diffusion tensors within voxels. We adapt frameworks proposed by Hext and Snedecor, where the null hypothesis of diffusion tensors belonging to the same distribution is assessed by an F‐test. Tissue type is classified according to one of the four possible diffusion models, the assignment of which is determined by a parsimonious model selection framework based on Schwarz Criterion. Both numerical phantoms and diffusion‐weighted imaging (DWI) data obtained from excised rat and pig spinal cords are used to test and validate these tissue clustering and classification approaches. The unsupervised clustering method effectively identifies distinct regions of interest (ROIs) in phantoms and real experimental DTI data. Copyright © 2009 John Wiley & Sons, Ltd.     

某养老机构新型冠状病毒肺炎聚集性疫情流行病学特征分析

目的对某养老机构发生一起新型冠状病毒肺炎(COVID-19)聚集性疫情进行回顾性流行病学调查和分析。方法采用"新型冠状病毒肺炎防控方案(第三版)"推荐的个案调查表和依照"新型冠状病毒肺炎聚集性疫情流行病学调查指南(试行第一版)"进行。结果某养老机构有8名护理人员和住院老人感染新冠肺炎,年龄中位为59岁,男、女比例1∶7。于末次暴露后4~15 d确诊。排查出225名密切接触者,无三代院内续发传播;不排除无症状感染存在传染的可能性;病亡1例。结论本次聚集性疫情的感染来源于新冠肺炎确诊病例。建议防控策略应关注养老机构、监管场所等重点部门、重点人群的管控与监测。     

Place cell firing correlates with memory deficits and amyloid plaque burden in Tg2576 Alzheimer mouse model

Alzheimer's disease (AD) is associated with progressive memory decline. Hippocampal place cells are a well understood candidate for the neural basis of one type of memory in rodents; these cells identify the animal's location in an environment and are crucial for spatial memory and navigation. We have recorded place cells in the Tg2576 mouse model of AD, and we report that aged (16 mo) but not young (3 mo) transgenic mice show degraded neuronal representations of the environment. The level of place cell degradation correlates with the animals' (poorer) spatial memory as tested in a forced-choice spatial alternation T-maze task and with hippocampal, but not neocortical, amyloid plaque burden. Place cell recording provides a sensitive assay for measuring the amount and rate of functional deterioration in animal models of dementia as well as providing a quantifiable physiological indication of the beneficial effects of potential therapies.     

Revealing the spatial distribution of a disease while preserving privacy

Datasets describing the health status of individuals are important for medical research but must be used cautiously to protect patient privacy. For patient data containing geographical identifiers, the conventional solution is to aggregate the data by large areas. This method often preserves privacy but suffers from substantial information loss, which degrades the quality of subsequent disease mapping or cluster detection studies. Other heuristic methods for de-identifying spatial patient information do not quantify the risk to individual privacy. We develop an optimal method based on linear programming to add noise to individual locations that preserves the distribution of a disease. The method ensures a small, quantitative risk of individual re-identification. Because the amount of noise added is minimal for the desired degree of privacy protection, the de-identified set is ideal for spatial epidemiological studies. We apply the method to patients in New York County, New York, showing that privacy is guaranteed while moving patients 25—150 times less than aggregation by zip code.     

早期康复训练联合行为学疗法治疗老年脑卒中偏瘫患者的效果分析

目的：探讨早期康复训练联合行为学疗法治疗老年脑卒中偏瘫患者的效果。方法依据随机数字表将75例老年脑卒中偏瘫患者随机分为对照组（38例）和观察组（37例）,两组均给予早期康复训练,仅观察组在此基础上加用行为学疗法;分析治疗前和治疗3、6个月后的步态能力（功能性运动量表 FAC）,下肢运动功能和平衡功能（简式 Fugl-Meyer 运动功能评定量表FMA）,步行相关指标（步速和跨步长度）,日常生活活动能力（Barthel 指数）及偏侧空间忽略情况（直线二等分、线段划消及画钟试验）。结果观察组治疗3 个月后的 FMA 评分中的运动功能、Barthel 指数均优于对照组（P ＜0．05）,且治疗 6个月后的FAC 评分、FMA 评分、步行相关指标、Barthel 指数及偏侧空间忽略情况均优于对照组（P ＜0．05）。结论早期康复训练联合行为学疗法治疗老年脑卒中偏瘫患者的效果较好,不仅可改善偏瘫步态和下肢功能,而且可改善偏侧空间忽略,可在脑卒中偏瘫患者患侧功能训练中实施。     

Stepped‐wedge cluster randomised controlled trials: a generic framework including parallel and multiple‐level designs

Stepped‐wedge cluster randomised trials (SW‐CRTs) are being used with increasing frequency in health service evaluation. Conventionally, these studies are cross‐sectional in design with equally spaced steps, with an equal number of clusters randomised at each step and data collected at each and every step. Here we introduce several variations on this design and consider implications for power. One modification we consider is the incomplete cross‐sectional SW‐CRT, where the number of clusters varies at each step or where at some steps, for example, implementation or transition periods, data are not collected. We show that the parallel CRT with staggered but balanced randomisation can be considered a special case of the incomplete SW‐CRT. As too can the parallel CRT with baseline measures. And we extend these designs to allow for multiple layers of clustering, for example, wards within a hospital. Building on results for complete designs, power and detectable difference are derived using a Wald test and obtaining the variance–covariance matrix of the treatment effect assuming a generalised linear mixed model. These variations are illustrated by several real examples. We recommend that whilst the impact of transition periods on power is likely to be small, where they are a feature of the design they should be incorporated. We also show examples in which the power of a SW‐CRT increases as the intra‐cluster correlation (ICC) increases and demonstrate that the impact of the ICC is likely to be smaller in a SW‐CRT compared with a parallel CRT, especially where there are multiple levels of clustering. Finally, through this unified framework, the efficiency of the SW‐CRT and the parallel CRT can be compared. © 2014 The Authors. Statistics in Medicine Published by John Wiley & Sons Ltd.     

A unifying modeling framework for highly multivariate disease mapping

Multivariate disease mapping refers to the joint mapping of multiple diseases from regionally aggregated data and continues to be the subject of considerable attention for biostatisticians and spatial epidemiologists. The key issue is to map multiple diseases accounting for any correlations among themselves. Recently, Martinez‐Beneito (2013) provided a unifying framework for multivariate disease mapping. While attractive in that it colligates a variety of existing statistical models for mapping multiple diseases, this and other existing approaches are computationally burdensome and preclude the multivariate analysis of moderate to large numbers of diseases. Here, we propose an alternative reformulation that accrues substantial computational benefits enabling the joint mapping of tens of diseases. Furthermore, the approach subsumes almost all existing classes of multivariate disease mapping models and offers substantial insight into the properties of statistical disease mapping models. Copyright © 2015 John Wiley & Sons, Ltd.