Development and Analysis of an Electrically Actuated Lower Extremity Assistive Exoskeleton

An electrically actuated lower extremity exoskeleton is developed,in which only the knee joint is actuated actively while other joints linked by elastic elements are actuated passively.This paper describes the critical design criteria and presents the process of design and calculation of the actuation system.A flexible physical Human-Robot-Interaction (pHRI) measurement device is designed and applied to detect the human movement,which comprises two force sensors and two gasbags attached to the inner surface of the connection cuff.An online adaptive pHRI minimization control strategy is proposed and implemented to drive the robotic exoskeleton system to follow the motion trajectory of human limb.The measured pHRI information is fused by the Variance Weighted Average (VWA) method.The Mean Square Values (MSV) of pHRI and control torque are utilized to evaluate the performance of the exoskeleton.To improve the comfort level and reduce energy consumption,the gravity compensation is taken into consideration when the control law is designed.Finally,practical experiments are performed on healthy users.Experimental results show that the proposed system can assist people to walk and the outlined control strategy is valid and effective.     

A new dissimilarity measure and a new optimality criterion in phytosociological classification

A new dissimilarity measure, Uppsala dissimilarity, is proposed. It is a Manhattan-type measure in between the Canberra and Gower measures, based on the differences between scores in relevés compared, but it also takes both the sums of scores and the difference between maximum and minimum score into account. The measure is considered realistic for phytosociological material.A new optimality criterion has been developed after unsatisfactory results had been obtained with the DOL criterion (Popma et al. 1983) which was developed previously by our group. Problems with DOL were especially met when the criterion was applied to the distribution of only one species over the cluster array obtained. The new criterion takes both internal cluster homogeneity and between-cluster dissimilarity into account. Between-cluster dissimilarity is calculated for all other clusters and not only for the nearest neighbour, as in DOL. The new criterion has both an unweighted form: SOM, and a form with weighting for cluster size: SWOM.This new criterion was successfully applied to the evaluation of the sharpness of distribution of individual species over cluster arrays, under the name of SIM: species indication measure and SWIM, species weighted indication measure.The measures were applied to some test data. Differences between the unweighted and weighted forms were found which could not be easily interpreted.Some remarks are made on the coherence of d-SAHN and h-SAHN approaches in agglomerative clustering within the new strategy proposed.Abbreviations DOL = Detection of Optimal Level - S(W)IM = Species (Weighted) Indication Measure - S(W)OM = Standardized (Weighted) Optimality Measure - UD = Uppsala Dissimilarity measure - WPGMA = Weighted Pair-Group Method Average linking clustering - SAHN = Sequential Agglomerative Hierarchical Non-overlapping clustering     

Identification of a threshold level to assess essential derivation in durum wheat

Essentially derived varieties (EDV) are considered to be those that are obtained from an original variety by means of methods that do not substantially modify its genetic structure, and whose characteristics are therefore derived from the original. The identification of EDV requires the definition of a threshold value of genetic similarity between the new and the original variety that if exceeded would suggest derivation. Although protocols for estimating genetic similarities based on molecular markers have been proposed for EDV identification in some species, no information was available for durum wheat (Triticum durum). A set of 60 genotypes (F8 or F9 lines and their parents) representing different levels of relatedness were profiled using 14 (later reduced to 13 by excluding the most deviant one) amplified fragment length polymorphism (AFLP) primer combinations and 109 simple sequence repeat (SSR) loci evenly distributed in the genome. For both marker types, an EDV threshold was calculated according to the “tail principle” on the distributions of Jaccard similarities among the subset of 39 independent genotypes. For all pairs of closely related lines branched in advanced generations (F7–F8), or for all but one pairs of lines deriving from the same F4 family, similarities exceeded the thresholds for both marker types, indicating a very good agreement in showing cases of suspected derivation. Compared to SSR markers, AFLP markers appear more suitable for assessing essential derivation because of their superior cost-efficiency. Based on 13 AFLP primer combinations, a threshold of 0.96 Jaccard similarity is proposed, below which a variety should be considered to be independently derived.     

Steady-state rate of F1-ATPase turnover during ATP hydrolysis by the single catalytic site

Under the conditions of ATP regeneration and molar excess of nucleotide-depleted F1-ATPase the enzyme catalyses steady-state ATP hydrolysis by the single catalytic site. Values of Km = 10(-8) M and Vm = 0.05 s-1 for the single-site catalysis have been determined. ADP release limits single-site ATP hydrolysis under steady-state conditions. The equilibrium constant for ATP hydrolysis at the F1-ATPase catalytic site is less than or equal to 0.7.     

The Conversion of 1-(Malonylamino)cyclopropane-1-Carboxylic Acid to 1-Aminocyclopropane-1-Carboxylic Acid in Plant Tissues

Since 1-(malonylamino)cyclopropane-1-carboxylic acid (MACC), the major conjugate of 1-aminocyclopropane-1-carboxylic acid (ACC) in plant tissues, is a poor ethylene producer, it is generally thought that MACC is a biologically inactive end product of ACC. In the present study we have shown that the capability of watercress (Nasturtium officinale R. Br) stem sections and tobacco (Nicotiana tabacum L.) leaf discs to convert exogenously applied MACC to ACC increased with increasing MACC concentrations (0.2-5 millimolar) and duration (4-48 hours) of the treatment. The MACC-induced ethylene production was inhibited by CoCl₂ but not by aminoethoxyvinylglycin, suggesting that the ACC formed is derived from the MACC applied, and not from the methionine pathway. This was further confirmed by the observation that radioactive MACC released radioactive ACC and ethylene. A cell-free extract, which catalyzes the conversion of MACC to ACC, was prepared from watercress stems which were preincubated with 1 millimolar MACC for 24 hours. Neither fresh tissues nor aged tissues incubated without external MACC exhibited enzymic activity, confirming the view that the enzyme is induced by MACC. The enzyme had a K_m of 0.45 millimolar for MACC and showed maximal activity at pH 8.0 in the presence of 1 millimolar MnSO₄. The present study indicates that high MACC levels in the plant tissue can induce to some extent the capability to convert MACC to ACC.     

Significance of plasma MACC1 levels on the prognostic stratification in patients with colorectal cancer

The clinical significance of metastasis‐associated in colon cancer‐1 (MACC1) has been investigated but the relevance of peripheral MACC1 levels was rather limited. Herein, our data revealed that plasma MACC1 levels in 117 colorectal cancer patients (CRC) were dramatically higher than that in normal controls (P < 0.001), and with a strong discrimination power between the two groups (AUC = 0.960, P < 0.001). Moreover, MACC1 is an independent prognostic factor for CRC patients. When clinical parameters stratified by MACC1_low and MACC1_high, MACC1 levels exhibited further significant predictive value. Summary, plasma MACC1 levels could be a useful prognostic and diagnostic biomarker, and could improve the prognostic value of traditional prognosticators for colorectal cancer patients.     

Estimation of Genome Size of Four Panax Species by Flow Cytometry*

Ginseng genus Panax, a member of family Araliaceae, consists of about 11 species in total. Most species of this genus are applied as tonic and medicinal plant resources. In this article, the genome size (C Value) of four ginseng species was estimated by flow cytometry using Oryza sativa as the internal reference. The results revealed that the C Values of four species are different from each other, and the C Value of Pnotoginseng is the largest, while the C Value of Pstipuleanatus is the smallest one.     

Intracellular Sites of Synthesis and Storage of 1-(Malonylamino)cyclopropane-1-Carboxylic Acid in Acer pseudoplatanus Cells

Vacuoles were isolated from Acer pseudoplatanus cells that were incubated with [¹⁴C]1-aminocyclopropane-1-carboxylic acid (ACC). The kinetics of [¹⁴C]1-(malonylamino)cyclopropane-1-carboxylic acid (MACC) formation are consistent with the interpretation that MACC is synthesized in the cytosol, transported through the tonoplast, and accumulated in the vacuole. Twenty hours after chasing the labeled ACC with unlabeled ACC and adding 1 millimolar unlabeled MACC, all the [¹⁴C]MACC synthesized is located in the vacuole. Whole cells preloaded with [¹⁴C]MACC and then submitted to a continuous washing out, readily release their cytosolic MACC until complete exhaustion. The half-time of MACC efflux from the cytosol, calculated by the technique of compartmental analysis, is about 22 minutes. In contrast, vacuolar MACC remains sequestered within the vacuole. The transport of labeled MACC into the vacuole is stimulated by the presence of unlabeled MACC in the suspension medium, probably as a result of a reduced efflux of the labeled MACC from the cytosol into the suspending medium.     

Enhancing the performance of hazard indexes in assessing hot spots of harbour areas by considering hydrodynamic parameters

The hazard assessment strategies for harbour areas usually rely on tools able to predict environmental threats posed by contaminated sediments, mostly based on biological and chemical parameters and distinctly less on hydrological factors. Although ports are considered semi-enclosed and low-energy systems with scarce capacity to disperse contaminants to the open sea, the hydrological pattern established within the port basin cannot be neglected, especially when the localisation of hot spots is required for clean-up and remediation actions. In the present study we considered both approaches (biological/chemical and hydrological) for assessing hot spots of harbour areas. In particular, the relationship between the sediment hazard assessment c_NWAC (cumulative Normalized and Weighted Average Concentration) index (which is based on chemical and biological data) and a properly selected hydrodynamic parameter (the bottom shear stress) of the port area was investigated. This study demonstrates that marine currents influence significantly the fine-grained fraction distribution of the surficial sediments, and thus, the spatial and temporal variability of contaminant concentration. The evaluation of hydrodynamic parameters enhances the performance of hazard tools in the localization of areas of most concern and thus a detailed knowledge of the hydrodynamic features of the port seabed is advisable before defining a proper characterisation strategy for the harbour area.     

Modeling the effect of flow heterogeneity on coronary permeability-surface area

In 11 anesthetized pigs, the left anterior descending coronary artery (LAD) was cannulated and pump perfused with blood before and during maximum adenosine vasodilation. For LAD plasma flows (F) ranging from 0.42 to 3.6 ml.min-1.g perfused tissue-1, we injected radiolabeled microspheres to measure heterogeneity and used the multiple indicator-dilution method to measure permeability-surface area product (PS) for EDTA. Heterogeneity of flow from the LAD was expressed as relative dispersion (RD) = standard deviation of flow/mean flow. Values of RD, corrected for tissue sample size using fractal theory, ranged from 13 to 87%, approaching 16-35% at high F. We developed a "variable-recruitment model" of regional heterogeneous capillary transport to correct PS for flow heterogeneity and capillary surface area recruitment. Values of PS ranged from 0.14 to 0.96 ml.min-1.g-1. Accounting for heterogeneity increased PS values by 0-18% compared with homogeneous values. Results revealed PS to be proportional to flow up to F = 1.5-2.1 ml.min-1.g-1 and then was constant at higher flows. The initial increase of PS with F may be due to capillary recruitment. When full recruitment is reached, PS becomes independent of F. We conclude that flow heterogeneity is significant but not readily predictable in the pig myocardium and that the use of microspheres to correct indicator-dilution data for flow heterogeneity improves the interpretation of multiple-tracer studies, particularly when tracers are used to study interventions that may alter flow distribution.     

Accumulation of 1-(malonylamino)cyclopropane-1-carboxylic acid in ethylene-synthesizing tobacco leaves

During the hypersensitive reaction of Samsun NN tobacco to tobacco mosaic virus (TMV) the inoculated leaves synthesize large quantities of ethylene. At the same time, 1-(malonylamino)cyclopropane-1-carboxylic acid (MACC), a conjugate of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) accumulates. Smaller amounts of MACC are formed concomitant with ethylene synthesis during the normal development of tobacco leaves. The conjugate appears neither to be hydrolysed to liberate ACC, nor to be transported to other plant parts. Its accumulation thus reflects the history of the operation of the pathway of ethylene synthesis in the leaf. In floating leaf discs exogenously applied ACC was converted only slowly to both ethylene and MACC. More ethylene and less MACC were produced in darkness than in light, suggesting that environmental conditions may influence the ratio at which ACC in converted to either ethylene or MACC.     

The effect of water stress on 1-(malonylamino)cyclopropane-1-carboxylic acid concentration in plant tissues

Since the discovery of1-(malonylamino)cyclopropane-1-carboxylic acid (MACC)as a major metabolite of both endogenous andexogenously applied 1-aminocyclopropane-1-carboxylicacid (ACC), it has become evident that the formationof MACC from ACC can act to regulate ethyleneproduction in certain tissues. Hence it was suggestedthat MACC could serve as an indicator of water-stresshistory in plant tissues. The accurate quantificationof MACC in plant tissues is essential forunderstanding the role of MACC in the regulation ofethylene biosynthesis.Hoffman et al. [15] described a method for themeasurement of MACC in which MACC was hydrolysed byHCl to ACC, which was then assayed by chemicaloxidation to form ethylene. Attempts have been made byothers to raise monoclonal antibodies to MACC so thatan immunoassay could be developed in order to gain adeeper understanding of stress-induced ethyleneproduction but no further publications have beenforthcoming.Here a method employing GC-MS is compared with theindirect assay for MACC, which is based uponhydrolysis of MACC to ACC and conversion of ACC byhypochlorite reagent to ethylene which is subsequentlyquantified by GC.     

Knockdown of MACC1 expression suppressed hepatocellular carcinoma cell migration and invasion and inhibited expression of MMP2 and MMP9

Expression of MACC1 (metastasis-associated in colon cancer-1) protein is associated with metastasis of various human cancers. This study analyzed MACC1 protein expression in hepatocellular carcinoma (HCC) tissue specimens and then investigated the effects of MACC1 knockdown on HCC cell migration and invasion, and gene expression levels. Sixty pairs of HCC and adjacent normal liver tissues from HCC patients were analyzed for MACC1 expression immunohistochemically. The HCC cell lines Hep3B, Huh7, MHCC97H, SMMC-7721, Bel-7402, and HepG2 and the normal liver cell line LO2 were used to assess expressions of MACC1 mRNA and MACC1 protein using qRT-PCR and western blot, respectively. MACC1 short hairpin RNA (shRNA) was used to knockdown MACC1 protein expression in Huh7 cells. Changes in the tumor phenotype of these cells were analyzed with wound healing assay and invasion assays, and differences in gene expression were evaluated via western blot. Immunofluorescence was used to locate MACC1 protein in the above cell lines. MACC1 was highly expressed in HCC tissues and the nuclear expression of MACC1 protein was associated with poor tumor differentiation and intrahepatic metastasis or portal invasion. Moreover, MACC1 mRNA and MACC1 protein was also expressed in HCC cell lines. Immunostaining showed that MACC1 protein was localized in both nuclei and cytoplasm of HCC cell lines and the nuclear localization of MACC1 protein was associated with increased aggressiveness of HCC in cell lines. Knockdown of MACC1 expression using MACC1-shRNA reduced Huh7 cell migration and invasion abilities, which was associated with downregulation of MMP2, MMP9, and c-Met proteins in Huh7 cells. Localization of MACC1 protein to the nucleus may predict HCC progression. Knockdown of MACC1 expression using MACC1 shRNA warrants further evaluation as a novel therapeutic strategy for control of HCC.     

MACC1在结肠癌中表达及其临床病理意义

目的：观察MAccl（metastasis．associatedincoloncancer-1）在结肠癌中的表达并分析其与大肠癌临床病理特征的关系。方法：选择我院2001年1月～2011年12月收治的317例接受结肠癌根治术治疗的结肠癌患者为研究对象,通过免疫组织化学技术检测MACCl在结肠癌及癌旁正常结肠组织中的表达,并分析MACCl的表达与结肠癌患者临床病理指标和生存期的相关性。结果：MACCl在结肠癌中的阳性表达率选择高于癌旁正常结肠组织（P〈0．05）。MACCl的表达与肿瘤的大小、临床分期、淋巴结转移、远处转移均显著相关（P〈0．05）,MACCl阳性表达病例的肿瘤体积较MACCl阴性表达病例大,临床分期较MACCl阴性表达病例晚,淋巴结转移和远处转移的发生率较MACCl阴性表达者高,均有统计学意义（P〈0．05）。MACCl阳性表达病例的生存率和生存期均较MACCl阴性表达病例显著降低和缩短（P=0．01）。结论：MACCl的表达上调与结肠癌的发生发展密切相关,可能作为评估结肠癌患者预后的参考指标。     

MACC1蛋白在食管癌中的表达及其临床意义

目的：探讨结肠癌转移相关基因1（metastasis—associated in colon cancer-1,MACCl）在食管癌组织中的表达及其临床意义。方法：采用免疫组化EnVinsion法检测MACCl蛋白在88例食管癌组织中的表达,统计学分析MACCl蛋白在不同病理分级、TNM分期中表达的差异性。结果：免疫组化结果显示MACCl蛋白的阳性表达主要位于胞浆中。MACCl蛋白在食管癌组织中的总阳性率为88．64％;在I、II、Ⅲ级食管癌组织中的阳性率分别为14．29％、93．65％、100％,经Kruskal．WallisH检验差异性非常显著（P=0．0000）;在I、IIa、IIb、Ⅲ期食管癌中的阳性率分别是16．67％、89．47％、100％、100％,经Kruskal．WallisH检验差异性非常显著（P=0．0000）。结论：MACCl蛋白在食管癌中呈过度表达,其表达与病理分级、TNM分期相关,提示MACCl可能在食管癌的发生、发展中起重要作用。MACCl蛋白可能成为检测食管癌的发病及判断预后的生物学指标之一。     

Thermodynamics and muscle contraction. II. Consequences of the principle of maximization of the rate of entropy production]

For non-elastic irreversible mechanochemical machines of the muscular type, the above-mentioned principle (by H. Ziegler) leads to the following results. The velocity of shortening, v, decreases when the force F increases. The mechanical power of the system Fv, is active when 0 greater than v greater than vF=0 or 0 greater than F greater than Fv=0. At F=0 the rate of chemical reaction has the maximum and dQ/dF = -v greater than 0 (where Q is the rate of heat production). At v = 0 the rate of entropy production has the minimum and d/dv = F/A greater than 0 (where A is an affinity of the chemical reaction). The Onsager symmetry relation holds at v=0 only.     

Influence of the triazole growth retardant BAS 111..W on phytohormone levels in senescing intact pods of oilseed rape

Foliar treatment of oilseed rape plants (Brassica napus L.ssp. napus cv. Linetta) with the growth retardant BAS 111..W at the 5th leaf stage delayed pod senescence during early maturation. Changes of immunoreactive cytokinin- and abscisic acid (ABA)- like substances and of the ethylene precursor 1-aminocyclo-propane-1-carboxylic acid (ACC) and its malonyl-conjugate (MACC) were determined in intact whole pods. When compared with control plants, higher levels of total chlorophyll correlated with four-fold and three-fold increases of trans-zeatin riboside- and dihydrozeatin riboside-type cytokinins, respectively, in the pods of plants treated with 0.25 mg BAS 111..W per plant. Isopentenyladenosine-type cytokinins and ACC and MACC contents remained virtually unchanged, whereas ABA levels dropped considerably below those of controls (60% reduction). However, when analysed at late pod maturity, BAS 111..W treatment no longer affected the total chlorophyll content, or the levels of cytokinins, ABA, ACC and MACC. We hypothesize that the retardant-induced changes in the hormonal status of the pods, favouring the senescence-delaying cytokinins as opposed to abscisic acid, could contribute to the developmental delay.     

SAR in rats exposed in 2,450-MHz circularly polarized waveguides

Average specific absorption rates (SARs) for live rats exposed in 2,450-MHz circularly polarized waveguides were estimated from the total system loss determined from measurements using five power meters, and a correction factor representing actual SAR/apparent SAR. The actual SAR was measured by twin-well calorimetry and the apparent SAR by power meters. Values were obtained for carcasses of various body masses for five orientations. The average SAR with free movement in the cages changed less than threefold as the rats grew from 200 to 700 g. The ratio of peak to average SAR in the body was less than 3. These results indicate relatively constant energy disposition in rats exposed in the circularly polarized waveguide.     

Can Marmoset Mothers Count to Three? Effect of Litter Size on Mother–Infant Interactions

Harper (Parental Care in Mammals, Plenum Press, New York, 1981, p. 158) proposed that ‘there may be lower and upper limits for frequency or intensity of offspring stimulation that, on average, serve as reliable boundaries, below or above which it would be uneconomical to invest at all or at current levels.‘ This proposition was tested in captive common marmosets by comparing the responses of marmoset mothers exposed to differing number of infants. Fifteen common marmoset (Callithrix jacchus) litters (seven twin and eight triplet litters) from 11 different dams were observed for 6–12, 30‐min sessions over days 1–4 following birth. Mothers nursed smaller infants less frequently (F = 4.208, df = 1, 22; p = 0.052) regardless of litter size. The percent time mothers spent transporting (nursing and carrying) each infant was less for triplets than twins (F = 11.785, df = 1, 12; p = 0.005). Average transport bout length was significantly shorter for smaller infants (F = 7.566, df = 1, 22; p = 0.012) and was half as long for triplet infants as for twins (F = 10.733, df = 1, 7; p = 0.013). Twice as many transport bouts for triplets included maternal harassment of infants, than for twins (F = 42.742, df = 1, 24; p = 0.0001). Infant‐initiated transfers to the mother were more common for triplets than for twins (Mann–Whitney U = 79.50, p = 0.006). The overall maternal carrying score (% carry × number of infants carried) was lower for triplet litters than for twin litters (F = 15.38, df = 1, 3; p = 0.029); i.e. mothers of triplets did not, overall, invest in more carrying and nursing than did mothers of twins but instead invested less. These findings suggest that, as opposed to the strong attraction to infants that is common for many primates, the marmoset mother's tolerance for carrying infants does not increase with increasing infant stimuli present; rather, marmoset mothers will only tolerate a limited amount of time transporting and nursing infants, regardless of litter size. This limited tolerance may be due to the species’ small body size and anti‐predator strategies (e.g. concealment) that make infant care incompatible with other essential activities, such as foraging.     

Acetylcholine receptors in normal and denervated rat diaphragm muscle. I. Purification and interaction with [125I]-alpha-bungarotoxin.

Acetylcholine receptors have been purified from junctional regions of normal rat diaphragm muscle and from extrajunctional regions of denervated diaphragm. The reaction of purified receptors with [122I]-alpha-bungarotoxin has been investigated by kinetic methods. The toxin-receptor complexes dissociated in a biphasic manner at 35 degrees with a rapidly dissociating component (t1/2 = 4 hr) and a slowly dissociating component (t1/2 is greater than or equal to 100 hr). The association reaction between toxin and receptor did not obey simple second-order kinetics but could be analyzed in terms of two classes of binding sites corresponding to the two rates of dissociation. This treatment of the data allowed derivation of association rate constants for the two sites. Value obtained for the dissociation constants were 3.7 times 10(-10) and less than or equal to 0.4 times 10(-10) M for the junctional receptor and 1.7 times 10(-10) and is less than or equal to 0.2 times 10(-10) M for the extrajunctional receptor. In each case it is the more tightly binding component that associates and dissociates more slowly. Receptors present in crude preparations were comparable to purified receptors in their reaction with [125I-alpha-bungarotoxin. The validity of the two site model is discussed in relation to the kinetic studies.