链式可变形机器人的构形与运动研究

本文的研究内容围绕中国科学院创新基金和GUCAS-BHPB基金资助的项目“可变形机器人的研究”展开，其目的是研制具有较强环境适应能力和高机动性能的可变形移动机器人系统，为我国在灾难救援和特种作业等应用领域提供技术储备。论文首先对可变形机器人的研究现状进行了概述，接下来展开了三个方面的研究工作：平台方面，提出了一种新型可变形链式结构，并进行了结构设计和实验验证；构形方面，提出了基于相似理论的构形研究方法，对链式可变形机器人的构形设计和构形转化方法进行了研究；运动性能方面，通过理论和实验分析了链式可变形履带模块机器人不同构形的转向性能、越障性能和倾翻稳定性能等。各种用于非结构环境的移动机器人机构中，模仿生物蛇原型的链式机构由于具有多于确定空间位置和姿态所需的自由度，能够有效、迅速、可靠地响应许多复杂的作业任务，但是该类系统具有转向半径大和侧向稳定性差等缺点。在非结构环境中，机器人需要通过“以变应变”才能够应对复杂多变的任务和环境。因此，论文基于偏置关节的思想，提出了一种形态和结构均能够变化的新型链式结构。机器人的单个标准模块由模块本体、连接臂和偏置关节等组成。偏置关节避免了模块间的运动干涉，扩大了机器人模块间的相对运动空间。机器人模块的数量可以根据实际需要选择，机器人通过变形可以产生多种构形，同时每种构形又具有多种步态以适应作业任务的需要。根据变形机理，研制了链式可变形机器人样机，并对样机进行了相应的原理验证实验。链式可变形机器人构形的复杂性随着模块数量和构形数量的增加呈指数增长，增加了构形设计和构形控制的难度。针对构形设计和构形转化问题，本文基于相似理论，提出了构形研究的一般分析方法，并将其归纳成为：表达(Expression)、计数(Enumeration)、评价(Evaluation)和有效性(Efficiency)等四个方面的问题(简称“Four-E Problem”)。在构形设计方面，根据模块的物理结构和邻接关系提出了用构形矩阵来表达机器人结构的拓扑信息，并在仿真环境下进行有效的描述；提出了基于组合计数原理的递归算法用于多模块可变形机器人非同构构形的计数、枚举，并根据构形矩阵所表征的拓扑信息对构形进行评价；最后根据仿真结果，给出了可变形机器人的构形设计示例。在构形转化方面，论文利用图论中的基本思想和原理对机器人的构形和构形网络进行了建模，对构形转化的路径进行了计算，对构形转化的最佳路径和中心构形的选择进行了分析；以三模块可变形机器人的构形网络为例，证实了该方法的可行性。履带式移动机器人的运动能力涉及的问题很多，包括接地比压、驱动能力、地面阻力、启动特性、转向能力、越障能力、平顺性和倾翻稳定性等。本文主要研究链式可变形履带模块机器人不同构形的平面转向特性、系统越障性能和倾翻稳定性能等。论文首先对链式可变形履带模块机器人单模块(单履带)的接地比压分布进行了研究，并对接地比压的核心区域进行了分析。在复杂的环境中，机器人运动的路径多由弯曲的道路组成，转向性能是其改变运动方向的一种重要能力。转向形式通常有滑移转向和铰接转向两种，分别适用不同的构形。论文参照杨红旗模型和Kitano模型分别对链式可变形双模块机器人和链式可变形三模块机器人不同构形下的滑移转向和铰接转向进行了理论和实验分析。移动机器人的越障性能是机器人本体和环境相互作用时所产生的一种综合特性。论文分析了链式可变形机器人系统的斜坡爬行性能、沟壑爬行性能、楼梯爬行性能和倾翻稳定性能。考虑到城市环境中，楼梯是最为典型的障碍物之一，论文重点对履带式移动机器人在踢面爬升、踢面翻越和坡度线爬行等阶段的运动条件、运动性能和影响因素进行了分析。在非结构环境中，大多数情况是坎坷不平的地面和复杂的三维地形，机器人的倾翻稳定性(或者说是抗倾翻能力)非常重要。根据Iagnemma和Papadopoulos提出的稳定性分析方法，定义机器人的倾翻稳定锥，对履带式可变形机器人变形过程中的倾翻稳定性进行了综合判定，同时通过仿真比较了机器人三种对称构形在仰俯、倾斜和偏转等组合干扰下的倾翻稳定性。稳定锥方法，为可变形机器人的倾翻问题提供了有效的理论分析手段，同时稳定锥方法还可以适用于其它轮式或腿式移动机器人的稳定性分析。理论分析和实验表明，本文研制的履带驱动链式可变形机器人平台，具有多种构形和步态以适应不同的环境和任务，具有废墟、砾石、草地、沙地、楼梯、坡度和管道等城市或野外环境的通过能力。可变形机器人机构灵巧、结构紧凑、便于携带，它不仅能够用于救援、消防、公安和环保等领域，在星球探测、国防安全等方面也有着潜在的应用前景。

Quantitative Inference in a Mechanical Design Compiler

This paper presents the ideas underlying a program that takes as input a schematic of a mechanical or hydraulic power transmission system, plus specifications and a utility function, and returns catalog numbers from predefined catalogs for the optimal selection of components implementing the design. It thus provides the designer with a high level "language" in which to compose new designs, then performs some of the detailed design process for him. The program is based on a formalization of quantitative inferences about hierarchically organized sets of artifacts and operating conditions, which allows design compilation without the exhaustive enumeration of alternatives.

Human Non-neutralizing HIV-1 Envelope Monoclonal Antibodies Limit the Number of Founder Viruses during SHIV Mucosal Infection in Rhesus Macaques.

HIV-1 mucosal transmission begins with virus or virus-infected cells moving through mucus across mucosal epithelium to infect CD4+ T cells. Although broadly neutralizing antibodies (bnAbs) are the type of HIV-1 antibodies that are most likely protective, they are not induced with current vaccine candidates. In contrast, antibodies that do not neutralize primary HIV-1 strains in the TZM-bl infection assay are readily induced by current vaccine candidates and have also been implicated as secondary correlates of decreased HIV-1 risk in the RV144 vaccine efficacy trial. Here, we have studied the capacity of anti-Env monoclonal antibodies (mAbs) against either the immunodominant region of gp41 (7B2 IgG1), the first constant region of gp120 (A32 IgG1), or the third variable loop (V3) of gp120 (CH22 IgG1) to modulate in vivo rectal mucosal transmission of a high-dose simian-human immunodeficiency virus (SHIV-BaL) in rhesus macaques. 7B2 IgG1 or A32 IgG1, each containing mutations to enhance Fc function, was administered passively to rhesus macaques but afforded no protection against productive clinical infection while the positive control antibody CH22 IgG1 prevented infection in 4 of 6 animals. Enumeration of transmitted/founder (T/F) viruses revealed that passive infusion of each of the three antibodies significantly reduced the number of T/F genomes. Thus, some antibodies that bind HIV-1 Env but fail to neutralize virus in traditional neutralization assays may limit the number of T/F viruses involved in transmission without leading to enhancement of viral infection. For one of these mAbs, gp41 mAb 7B2, we provide the first co-crystal structure in complex with a common cyclical loop motif demonstrated to be critical for infection by other retroviruses.

Appropriateness of Largemouth Bass as a Model Species for Detection of Endocrine Dissruption

Intersex in largemouth bass (Micropterus salmoides) has been correlated with regional anthropogenic activity, but has not been causally linked to environmental factors. Four groups of hatchery-reared largemouth bass (LMB) and fathead minnows (FHM) of varying ages and sex were exposed to aqueous poultry litter mixtures, 17β- estradiol (E2), and controls. Water samples were analyzed for estrogens through liquid chromatography tandem mass spectrometry and estrogenicity through the bioluminescent yeast estrogen screen assay. Fish plasma was analyzed for the egg yolk protein vitellogenin (Vtg) using enzyme–linked immunosorbent assay and gonad tissue was examined histologically for enumeration of testicular oocytes (TO). Water chemistry revealed typical E2 conversion to Estrone with subsequent decay over the exposure periods. A modest prevalence of TO (9.4%) was detected with no apparent treatment effect. While significant Vtg induction was found in E2 exposed FHM, minimal Vtg induction was found in male LMB. Despite field findings of intersex in male LMB, this species may be poorly suited for laboratory investigations into endocrine disruption.

Prevalence of early and late age-related macular degeneration in a rural population in Northern India: The INDEYE Feasibility Study

PURPOSE. To assess the prevalence of age-related macular degeneration (AMD) in a rural population in Northern India. METHODS. In a pilot feasibility study, 1443 people (median age, 60 years; 52% women), were identified from enumeration of the 50+ age group in 11 randomly sampled villages from a rural, periurban district of Haryana, Northern India. Of those identified, 87% attended an eye examination that included digital fundus photography. Fundus images were graded at a single reading center using definitions from the Wisconsin Age-Related Maculopathy Grading System. RESULTS. Fundus photographs were available for 1101 participants. Overall, 28.8% of participants had ungradable fundus images due to cataract. Including all with ungradable images in the denominator, the prevalence of soft drusen was 34.0% (95% confidence interval [CI] 26.1–42.9); of soft indistinct drusen, 2.2% (95% CI, 1.1–4.4); and of pigmentary irregularities, 10.8% (95% CI, 7.1–16.1). There were 15 (1.4%) cases of late-stage AMD (95% CI, 0.8–2.3) with the prevalence rising from 0.4% in the 50- to 59-year age range to 4.6% in those aged 70 years or older. CONCLUSIONS. Drusen and pigmentary irregularities are common among the rural northern Indian population. The prevalence of late AMD is similar to that encountered in Western settings and is likely to contribute significantly to the burden of vision loss in older people in the developing world.

Unlinked vital events in census-based longitudinal studies can bias subsequent analysis

Objective: To examine the potential biases arising from the nonlinkage of census records and vital events in longitudinal studies.
Study Design and Setting: A total of 56,396 deaths of residents of Northern Ireland in the 4 years after the 2001 Census were linked to the 2001 Census records. The characteristics of matched and nonmatched death records were compared using multivariate logistic regression. Subject attributes were as recorded on the death certificate.
Results: In total, 3,392 (6.0%) deaths could not be linked to a census record. Linkage rates were lowest in young adults, males, the unmarried, people living in communal establishments, or living in areas that were more deprived or had recorded low census enumeration. For those aged less than 65 years at census, this linkage would exclude from analysis 20.2% of suicides and 19.7% of deaths by external causes.
Conclusion: The nonlinkage of census and death records is a combination of nonenumeration at census and deficient information about the deceased recorded at the time of death. Unmatched individuals may have been more disadvantaged or socially isolated, and analysis based on the linked data set may therefore show some bias and perhaps understate true social gradients.

Maximising capture efficiency and specificity of magnetic separation for Mycobacterium avium subsp. paratuberculosis cells

In order to introduce specificity for Mycobacterium avium subsp. paratuberculosis prior to a phage amplification assay, various magnetic-separation approaches, involving either antibodies or peptides, were evaluated in terms of the efficiency of capture (expressed as a percentage) of M. avium subsp. paratuberculosis cells and the percentage of nonspecific binding by other Mycobacterium spp. A 50:50 mixture of MyOne Tosylactivated Dynabeads coated with the chemically synthesized M. avium subsp. paratuberculosis-specific peptides biotinylated aMp3 and biotinylated aMptD (i.e., peptide-mediated magnetic separation [PMS]) proved to be the best magnetic-separation approach for achieving 85 to 100% capture of M. avium subsp. paratuberculosis and minimal (<1%) nonspecific recovery of other Mycobacterium spp. (particularly if beads were blocked with 1% skim milk before use) from broth samples containing 103 to 104 CFU/ml. When PMS was coupled with a recently optimized phage amplification assay and used to detect M. avium subsp. paratuberculosis in 50-ml volumes of spiked milk, the mean 50% limit of detection (LOD50) was 14.4 PFU/50 ml of milk (equivalent to 0.3 PFU/ml). This PMS-phage assay represents a novel, rapid method for the detection and enumeration of viable M. avium subsp. paratuberculosis organisms in milk, and potentially other sample matrices, with results available within 48 h.

Religious Geographies in Ireland: Pre-Famine, Post-Famine, Pre-Partition

This paper examines changes in religious geographies for Ireland from 1834 to 1911. It shows that in a period of dramatic social and economic change religious geographies remained remarkably stable. In this it challenges the accepted historiography. It makes use of new data in new ways with the full exploitation of the 1834 Enumeration of Religion and, in so doing, is able to examine the impact of the Great Irish Famine on geographies of religion. These data are visualised both using traditional choropleth maps and, more innovatively in this subject area, cartograms.

Habitat effects on the spatial ecology of the European badger (Meles meles)

This study investigates how habitat variation affects sett density, the number of animals per social group and group territory size in the badger (Meles meles). Identical methods were applied in three habitat types: lowland parkland with mixed woodland, pastoral farmland and upland rough pasture with moorland, representing areas of presumed good, medium and poor badger habitat, respectively. Contiguous main setts were identified and bait-marking was used to estimate territory size. Group size was estimated by direct enumeration. Variation in sett density, group size and territory size supported the hypothesis that badger group and territory size are influenced by habitat type. This was further supported by analyses of data from other studies in the British Isles. The implications for badger spatial ecology, badger survey techniques and the badger's role in the epidemiology of TB are discussed.

The removal of patients who live outside the practice boundary:a study of outside-area removals in Northern Ireland in 2001-2002

It has been suggested that there are significant overlaps between removals due to deregistration and removals arising because patients live outside the practice area. If this is true, it would mean that the current estimates of deregistration would need to be revised upwards. All outside-area removals for the calendar years 2001 and 2002 were reviewed and characterised by age, sex and Jarman score of the enumeration district of the patients' residence and distance from the practice. The average outside-area removal rate was just over one removal per practice per year. Removal rates were highest between the ages of 18 and 44 years; there were no significant differences between the sexes. Rates of removal increased exponentially with distance, although even at marked distances from the practice there were about 10 patients remaining on the list for each one removed. Residents in deprived areas were more likely to be removed, although because areas most distal to the practice tend to be affluent, overall there was a predominance of affluent patients among those who are removed. In Northern Ireland rates of outside-area removal are only slightly higher than those of deregistration. It is evident that GPs are exercising some discretion as to which of the outside-area patients they retain on their list. This has the potential to cause some misunderstanding and resentment among patients, as has been reported previously.

General practitioner deprivation payments in Northern Ireland:is the current system equitable?

The allocation of General practitioners deprivation payments has been a contentious issue since it was first proposed. This paper examines the method of allocation of such payments in Northern Ireland. A more equitable system would be based on enumeration districts, have a lower Jarman score and a closer relationship between Jarman score and remuneration. Unlike other parts of the UK these changes are now possible in Northern Ireland and should be implemented.

More equitable systems for allocating general practice deprivation payments:financial consequences

The allocation of general practitioner (GP) deprivation payments has been a controversial topic since they were first proposed. It has recently been suggested that the current system could be made more equitable if the payments were allocated at enumeration districts and if there was a more graded relationship between Jarman score and funding. However, the implications of these changes on the distribution of deprivation payments have not been worked out.

Age-related reference intervals for lymphocyte subsets in whole blood of healthy individuals

Enumeration of various lymphocyte subsets is used widely in the diagnosis and monitoring of various disease states. With the development of flow cytometric technology and whole blood analysis, methodologies have become more sensitive. It is therefore important to establish reference intervals in normal, healthy individuals using these techniques to give a better indication of the border between health and disease. Since some lymphocyte subpopulations are known to change with age, we have enumerated common subsets in healthy individuals from all decades of adult life, including nonagenarian subjects. We report reference intervals for these subsets in each age group, which will be of use in diagnosis and disease monitoring, particularly in elderly subjects, the most rapidly expanding group within the population today.

Combined effect of high pressure processing and antimicrobial packaging to control the growth of Listeria monocytogenes on ready-to-eat chicken breast

In the European Union, food is considered safe with regard to Listeria monocytogenes if its numbers do not exceed 100 cfu/g throughout the shelf-life of the food. Therefore, it is important to determine if a food supports growth of L. monocytogenes. Challenge tests are laboratory-based studies that measure the growth of L. monocytogenes on artificially contaminated food stored under foreseeable conditions of transportation, distribution and storage. The aim of this study was to elaborate and optimize a user-friendly protocol to perform challenge tests on food and to apply it to determine whether growth of L. monocytogenes is supported during the production and distribution of a potentially risky food i.e. mushrooms. A three-strain mixture of L. monocytogenes was inoculated onto three independent batches of whole mushrooms, sliced mushrooms, mushroom casing and mushroom substrate at a concentration of about 100 -1000 cfu/g. The batches were incubated at potential abuse temperatures, as a worst case scenario, and at intervals during storage L. monocytogenes numbers, % moisture and pH were determined. The results showed that the sliced and whole mushrooms supported growth of L. monocytogenes while mushroom casing allowed survival but did not support growth. Mushroom substrate showed a rich background microflora able of growing in Listeria selective media which hindered enumeration of L. monocytogenes. Combase predictions were not always accurate, indicating that challenge tests are a necessary part of growth determination of L. monocytogenes.

People and places: Understanding geographical accuracy in administrative data from the census and healthcare systems

Administrative systems such as health care registration are of increasing importance in providing information for statistical, research, and policy purposes. There is thus a pressing need to understand better the detailed relationship between population characteristics as recorded in such systems and conventional censuses. This paper explores these issues using the unique Northern Ireland Longitudinal Study (NILS). It takes the 2001 Census enumeration as a benchmark and analyses the social, demographic and spatial patterns of mismatch with the health register at individual level. Descriptive comparison is followed by multivariate and multilevel analyses which show that approximately 25% of individuals are reported to be in different addresses and that age, rurality, education, and housing type are all important factors. This level of mismatch appears to be maintained over time, as earlier migrants who update their address details are replaced by others who have not yet done so. In some cases, apparent mismatches seem likely to reflect complex multi-address living arrangements rather than data error.