Modeling and dynamic simulation of astronaut’s upper limb motions considering counter torques generated by the space suit

Extravehicular activity (EVA) is an inevitable task for astronauts to maintain proper functions of both the spacecraft and the space station. Both experimental research in a microgravity simulator (e.g. neutral buoyancy tank, zero-g aircraft or a drop tower/tube) and mathematical modeling were used to study EVA to provide guidance for the training on Earth and task design in space. Modeling has become more and more promising because of its efficiency. Based on the task analysis, almost 90% of EVA activity is accomplished through upper limb motions. Therefore, focusing on upper limb models of the body and space suit is valuable to this effort. In previous modeling studies, some multi-rigid-body systems were developed to simplify the human musculoskeletal system, and the space suit was mostly considered as a part of the astronaut body. With the aim to improve the reality of the models, we developed an astronauts’ upper limb model, including a torque model and a muscle-force model, with the counter torques from the space suit being considered as a boundary condition. Inverse kinematics and the Maggi-Kane’s method was applied to calculate the joint angles, joint torques and muscle force given that the terminal trajectory of upper limb motion was known. Also, we validated the muscle-force model using electromyogram (EMG) data collected in a validation experiment. Muscle force calculated from our model presented a similar trend with the EMG data, supporting the effectiveness and feasibility of the muscle-force model we established, and also, partially validating the joint model in kinematics aspect.     

Surgical anatomy of the midcheek and malar mounds

The anatomy of the midcheek has not been satisfactorily described to adequately explain midcheek aging and malar mounds, nor has it suggested a logical approach to their correction or provided sufficient detail for safe surgery in this area. This cadaver study, which was complemented by many operative dissections, located a missing link: a glide plane space overlying the body of the zygoma. The space functions to allow mobility of the orbicularis oculi, where it overlies the zygoma and the origins of the elevator muscles to the upper lip. The space is a cleft between the sub-orbicularis oculi fat and the preperiosteal fat and is lined by a fine membrane. The anatomic boundaries are clearly defined by retaining ligaments, which correlate with the triangularity of the space. Several anatomic features provide the functional characteristics of the prezygomatic space, including the (1) absence of direct attachments between the orbicularis in the roof to the floor, (2) more rigid inferior boundary formed by the zygomatic ligaments, and (3) more mobile upper ligamentous boundary formed by the orbicularis retaining ligament (separating from the preseptal space of the lower lid). These components determine the characteristic aging changes that occur in this region and explain much about malar mounds. An appreciation of this anatomy has several surgical implications. The prezygomatic space is a junction area that can be approached from the temple, lower lid, and cheek. The zygomatic branches of the facial nerve to the orbicularis do not cross the space; rather, they course in the walls and in the sub-orbicularis fat within the roof of the space.     

Eye Movements Induced by Changes in the Internal Representation of Body Posture

Oculomotor responses to body rotation were investigated in subjects standing with the eyes closed. A rotatable platform was used to provide body rotation relative to the space-stationary head or upper part of the body (fixation of the head; the head and the shoulders; and the head, the shoulders, and the pelvis). A slow rotation of the body about the longitudinal axis by ±6.5° within 10–150 s evoked an illusion of the upper part of the body turning in space, while the moving footplate was perceived as stationary in space. This illusion was accompanied by marked eye movements in the direction of the illusory rotation. In subjects grasping a rigid ground-based handle, the perception of body movements corresponded to the actual rotation of body parts. In this case, the amplitude of eye movements was substantially lower. It was concluded that the eye movement pattern depends not only on the actual relative movement of the body segments but also on the perception of this movement relative to the extrapersonal space.     

Strategy and synergy: two levels of equilibrium control during movement. Effects of the microgravity]

Equilibrium is ensured during forward or backward upper trunk movements by displacing the hip and knee simultaneously in opposite directions. When fast movements are performed, a muscle synergy characterized by the early activation of a set of trunk, thigh and leg muscles precedes the onset of the kinematic changes. The question which is addressed concerns the possibility that two levels of equilibrium control might exist during upper trunk movements: the strategy level, which is relatively invariant, is characterized by the displacement in opposite directions of the upper and low segments, and the muscle synergy level at which the strategy is implemented, which may be adaptable to the environmental constraints. When upper trunk movements are performed under microgravity with the subject's feet fixed to the floor of the space cabin, the displacement of upper and lower body segments in opposite directions still occurs, although this is no longer necessary to maintain the equilibrium. This kinematic strategy seems to be aimed at regulating the centre of inertia position with respect to the feet. The muscle synergies associated with these kinematic changes are modified, however, under microgravity. After returning to the ground, the previous synergies do not reappear immediately, but only after a few days. This suggests that a short period of learning is needed to change the synergy. These data are compatible with the hypothesis that two levels of equilibrium control actually exist during upper trunk movements, the strategy level, which is kinematic and invariant, and the synergy level, which is adaptable to the environmental constraints through a short learning process.     

土鳖虫与其混淆品的微性状鉴别研究

为对目前药材市场流通的中药材土鳖虫进行微性状特征研究,探究土鳖虫与其混淆品的区别。实验通过查阅资料,对市场土鳖虫品种进行调查,运用中药微性状鉴定法对土鳖虫的不同部位采用体视显微镜、生物显微镜、扫描仪等仪器进行图像采集,并利用Photoshop CS5软件景深合成高清晰度微性状特征图片来对其进行鉴别研究。实验结果表明,土鳖虫口器、腹背板边缘、肛上板、生殖板、触角、单眼间距与复眼间距比例、单眼、复眼、前足胫节、跗节、爪、尾须、背甲及腹甲刚毛等方面与混淆品有比较明显的区别。     

A Buddha Kingdom in the Golden Triangle: Buddhist Revivalism and the Charismatic Monk Khruba Bunchum

Khruba Bunchum Yanasangwaror, despite his youth, has already been proclaimed by many, in the Yuan Buddhist world of the upper Mekong region, to be a ton bun (‘source of merit’). His charismatic reputation derives from his ascetic virtues, his assumed accumulation of merit in past lives and his Bodhisattva‐like compassion for others. His compassion is expressed through dedication to the building of religious monuments that allows the laity to acquire merit by contributing labour and money. Another dimension of the conception of ton bun is that of sacral kingship. In these and other respects Khruba Bunchum's religious career emulates that of Khruba Siwichai, the famous northern Thai monk of the early 20th century. However, Khruba Siwichai's religious activities were confined to northern Thailand, whereas Khruba Bunchum's peregrinations throughout northern Thailand, northern Laos, Sipsongpanna (in China) and northeast Burma mark out a sacred Buddhist space, focused on the heart of the notorious Golden Triangle. I argue in this paper that this imagined sacred space both transcends and challenges the dominant discourse of modern nation‐state.     

Use of Plasma Flows to Clean the Near-Earth Space

Plasma Physics Reports - A system for cleaning near-Earth space from space debris in the upper layers of the atmosphere is proposed, which is based on a plasma accelerator that uses the medium of...     

Patterns in the use of rainforest vertical space by Neotropical aerial insectivorous bats: all the action is up in the canopy

In tropical rainforests environmental conditions vary dramatically from the ground to the canopy, resulting in a marked stratification in the way vertical space is used by organisms, but research work is often limited to the understorey layer. Aerial insectivorous bats are a highly diverse group that plays key roles in the ecology of rainforests, but their use of vertical space remains elusive. Using automatic ultrasound recording stations placed in the canopy, subcanopy and understorey we tested if bat activity and species diversity are vertically stratified, both in the forest interior and near the edges of water bodies. These patterns were tested separately for individual species, and for two functional groups – open space and edge space bats. Insectivorous bat activity increased by roughly seven fold, and species diversity doubled, from the understorey to the canopy. Both edge space and open space bats were more active in the upper strata, but this tendency was much more accentuated in the latter. Myotis riparius was the only species with greater activity near the understorey. These patterns were altered at the edges of water bodies, where vertical stratification was much less marked. The observed patterns are parsimoniously explained by constraints imposed by vegetation clutter that change across strata, which affect bat species differently. Only bats better adapted to closed spaces are usually capable of foraging within the understorey, whereas the majority of species can exploit the free spaces immediately below the canopy; open space bats seem to concentrate their activity above the canopy. This importance of the inter strata open spaces for bat foraging highlights the need to preserve pristine stratified rainforests, as even selective logging usually disrupts vertical stratification. Moreover, the concentration of insectivorous bats at the upper strata of rainforests underlines the need to include canopy level sampling in ecological studies.     

Enemy-free space and the feeding niche ofan aphid

1. The nymphs of the aphid Monaphis antennata occupy an unusual feeding niche, being restricted to the upper surfaces of leaves and petioles. The possibility that this is a predator-avoidance strategy was investigated.
2. Nymphs could be induced to feed on the under surfaces of petioles and the mortality of these nymphs was then compared with the mortality of nymphs feeding from the upper surfaces when exposed to coccinellid predators.
3. Coccinellid larvae spent less time foraging on the upper surfaces of leaves and petioles than on the under surfaces of leaves and petioles.
4. The nymphs occupying the upper surfaces of petioles, the normal feeding position, were encountered by the coccinellids later and less often, and fewer were attacked compared with those occupying the under surfaces.
5. It is concluded that the feeding niche of the nymphs of this aphid is adaptive in that it reduces exposure to foraging predators and is the result of selection to occupy enemy-free space.     

Defining the abundance body-size constraint space: data from a real food web

Using density and body-size data for a well-documented food web, the Ythan estuary, Aberdeenshire, we show that the shape of the constraint space is broadly similar to that proposed by Brown, and the slope (regression coefficient) of the plot of the central tendency is not significantly different from global or community data sets. However, the steepness of the plot is very sensitive to the degree of taxonomic resolution of species entities, particularly those of small body-size, although the overall shape of the constraint space does not change. When more fully resolved, the regression slope differs markedly from those of most freshwater and terrestrial studies. In addition, the upper bound of the constraint space is, contrary to theoretical expectations, insensitive to gross changes in the system's productivity. The dramatic increase in productivity that has led to an increase in abundance of invertebrates in the Ythan does not visibly affect the upper bound of the constraint space. Our results show that the traditional approach to comparing systems by the regression slopes of central trends is probably meaningless unless data sets are resolved to a similar degree of taxonomic resolution, and that detecting productivity effects on the location of the upper bound will be difficult.     

An upper limit for the electrogenic Na-K pump contribution to maximum diastolic potential in feline cardiac Purkinje fibers in steady state

We have estimated an upper limit for the electrogenic contribution of the Na-K pump to diastolic transmembrane potential. We simultaneously monitored the maximum diastolic potential and the extracellular space potassium activity during exposure to a very high concentration of ouabain. Exposure to ouabain caused a depolarization of approximately 3 mV (n = 33 experiments) over 34 +/- 3 s (mean +/- standard error) prior to any change in extracellular K activity. In four experiments, we monitored intracellular sodium activity and observed it to rise with approximately the same temporal lag (delay = 26 +/- 7 s). We also measured relative membrane conductance in one series of experiments and observed it to decrease to 91 +/- 2% of its control value by the time extracellular space K began to rise. Following the initial increase in extracellular space K activity the subsequent membrane depolarization is shown to be accurately predicted solely from the measured increase in extracellular space K activity as calculated from the Goldman equation. Limitations of the method and possible interpretations of the data are discussed. We interpret this ouabain-induced depolarization that occurs prior to the rise in external K to be an upper limit to the Na-K pump's electrogenic contribution to steady-state membrane potential.     

胸4～5椎间隙直视下硬膜外头端置管建立上胸段硬膜外阻滞大鼠模型

目的为上胸段硬膜外阻滞的动物试验研究提供经济、稳定、可靠的模型。方法以大鼠为研究对象,经胸4～5椎间隙,直视下向头端于硬膜外腔置入经拉撕等处理后的临床用硬膜外导管,采用椎旁肌肉缝扎导管,皮下隧道预留缓冲长度等方法固定导管。48 h后大鼠硬膜外腔注入美蓝100μL/kg,尸检鉴定模型成功和药液的分布范围。结果置管48 h后的成功率为85.8%,硬膜外腔的感染率为0,导管脱出几率5%。结论本研究证实了经胸4～5椎间隙直视下头端置管建立上胸段硬膜外阻滞大鼠模型的可行性,并具有损伤小、稳定性好、成功率高、费用低及周期短等优点。     

The effect of brefeldin A on the redistribution of osmiophilic particles and the gravitropic response of rye coleoptiles

Summary The occurrence of IAA-inducible osmiophilic particles (OPs) in the periplasmic space of epidermal cells in the upper and lower flank (UF, LF) of gravistimulated rye coleoptile segments was analyzed employing brefeldin A (BFA) as an inhibitor of secretion at the plasma membrane. A 2 h horizontal gravistimulation of untreated samples caused a duplication of OPs in the periplasmic space of epidermal cells at the growth-inhibited UF as compared to the LF of upward bending coleoptile segments. In contrast to this, the number of OPs within the cytoplasm close to the plasma membrane of epidermal cells was similar at both flanks. BFA caused an inhibition of graviresponsive growth and prevented the occurrence of OPs in the periplasmic space of the epidermal cells of the UF and the LF. Likewise, growth of vertically oriented coleoptile segments was inhibited by BFA. Growth inhibition of both gravistimulated and control segments was accompanied by a twofold increase of the occurrence of cytoplasmic OPs. The results illustrate that the occurrence of OPs within the periplasmic space of the epidermal cells depends on secretion processes. Furthermore they provide evidence that their increased occurrence in the growth-inhibited UF during gravistimulation is due to their inhibited infiltration into the cell walls. We suggest that thereby wall loosening is temporarily prevented.Abbreviations BFA brefeldin A - LF lower flank - OP osmiophilic particle - UF upper flank Dedicated to Professor Dr. Dieter Klämbt on the occasion of his 65th birthday     

Compartments and perivascular arrangement of the meninges covering the cerebral cortex of the rat

Summary The intercellular clefts of the brain and the leptomeninges, and the perivascular spaces were studied with reference to the results obtained in a previous study (Krisch et al. 1983). The spatial relationships of these compartments were analyzed at the electron-microscopic level. Horse-radish peroxidase (HRP) was injected into the brain or into the contralateral ventricle.The pattern of distribution of HRP depends on the boundary situation in the individual compartments. The inner and outer pial layers accompany the vessels intruding into the brain. In the Virchow-Robin space the pial funnel obliterates within a short distance. The inner arachnoid layer is continuous with the outer arachnoid layer when it covers the vessels traversing the meningeal space. The perivascular compartment is not in communication with the arachnoid space; moreover, the pial funnel within the Virchow-Robin space is sealed off against the arachnoid space.Thus, blood vessels traversing the meningeal spaces and subsequently penetrating the brain surface are exposed to the common intercellular compartment represented by the intercellular clefts of the brain and the leptomeninges; this compartment does not communicate with the other compartments. The cerebrospinal fluid located in this intercellular compartment is preferentially drained into the upper cervical lymph nodes.Supported by the Deutsche Forschungsgemeinschaft (Grant Nr. Kr 569/5) and the Stiftung Volkswagenwerk.     

Autoflora in the upper respiratory tract of Apollo astronauts.

The typical microbial inhabitants of the oral and nasal cavities of Apollo astronauts were identified before space flight and generally found to be similar to those previously reported for healthy male adults. Additional analyses of samples collected immediately after return of the Apollo 13, 14, 15, and 16 crew members to earth were performed to evaluate the effects of space travel on the microbial bioburden of the upper respiratory tract. In-flight cross-contamination and buildup of pathogens such as Staphylococcus aureus were noted, although significant increases in nonpathogenic species were absent. Other proposed alterations, such as dysbacteriosis (flooding of the mouth with a single species) and simplification of the autoflora, did not occur. Generally, the incidence and quantitation of each species after flight was within the preflight range, although the number of viable Haemophilus cells recovered from the mouth decreased significantly after space flight. Except for those minor alterations listed above, the aerobic and anaerobic bacterial components of the upper respiratory autoflora of Apollo astronauts was found to be stable after space flight of up to 295 h.     

Asymmetry of the latent periods of saccades in human depending on visual space complicity

Saccadic latencies of visually-guided saccades of 10 right-handed subjects with right-leading eyes were studied. Stimulation paradigm was spatially bidimentional, and stimuli were shown along horizontal and vertical meridians. Three traditional single step GAP - NO DELAY - OVERLAP temporal paradigms were used. In the first experiment, each paradigm was applied separately (simple visual space). In the second experiment, all the three paradigms were varied pseudo-random order and equiprobably, which complicated the time parameters of visual stimulation (complicated visual space). Asymmetry of visually-guided saccades along the vertical and horizontal meridians was revealed. The character of this asymmetry varied between subjects. MANOVA showed that the factor of visual space complicity (simple or complicated visual space) affected the latent period of saccades to a greater extent than the factor of stimulus lateralization (stimulus presentation in the left/right or upper/lower visual hemifields).     

Hyperthermophiles in the history of life

Today, hyperthermophilic ('superheat-loving') bacteria and archaea are found within high-temperature environments, representing the upper temperature border of life. They grow optimally above 80 degrees C and exhibit an upper temperature border of growth up to 113 degrees C. Members of the genera, Pyrodictium and Pyrolobus, survive at least 1h of autoclaving. In their basically anaerobic environments, hyperthermophiles (HT) gain energy by inorganic redox reactions employing compounds like molecular hydrogen, carbon dioxide, sulphur and ferric and ferrous iron. Based on their growth requirements, HT could have existed already on the early Earth about 3.9Gyr ago. In agreement, within the phylogenetic tree of life, they occupy all the short deep branches closest to the root. The earliest archaeal phylogenetic lineage is represented by the extremely tiny members of the novel kingdom of Nanoarchaeota, which thrive in submarine hot vents. HT are very tough survivors, even in deep-freezing at -140 degrees C. Therefore, during impact ejecta, they could have been successfully transferred to other planets and moons through the coldness of space.     

Stentless aortic valve implantation through an upper manubrium-limited V-type ministernotomy

In this piece of work, we attempt to highlight our approach and early experience with minimally invasive aortic valve replacement with aortic Freedom Solo stentless bioprosthesis performed through an upper manubrium-limited ministernotomy in the second intercostal space. The novel suturing technique is required for stentless aortic bioprosthesis implantation, and this, in its turn, will predetermine and influence the surgeon's choice for operative access. In our department, the feasibility of the approach was first assessed; aortic valve was replaced by stentless bioprosthesis in a total of 23 patients (mean age 57 ± 12 years). In all cases, a cardiopulmonary bypass was established by a central ascending aorta cannulation and peripheral percutaneous venous cannula insertion. This approach was found to be technically reproducible and safe. The surgical technique used is described in this article.     

Early definitive bone and soft-tissue reconstruction of major gunshot wounds of the face

The use of craniofacial surgical techniques, extended open reduction, rigid fixation with plates and screws, and the replacement of severely damaged or missing bone with immediate bone grafting in the treatment of complex facial fractures has been applied to the management of severe gunshot wounds of the face. Early definitive bone and soft-tissue reconstruction has been performed in 37 patients. One-hundred and seventy-seven primary bone grafts were utilized in 33 patients for orbital, nasal, zygomatic, and maxillary reconstruction. Twenty-six patients required mandibular repair with compression or reconstruction plates. Soft-tissue reconstruction was provided by a combination of flaps. Four patients had extensive soft-tissue loss replaced by free vascularized omental flaps. The omentum provided circumferential coverage of the mandibular reconstruction and reconstruction of the floor of the mouth and was then tunneled in a circle through both cheeks into the middle and upper face. The omentum reconstructed deficits in the hard palate and upper buccal sulcus and was then wrapped around all zygomatic, orbital, and midfacial bone grafts and used to fill in dead space in the maxillary, ethmoid, and frontal sinuses. The omentum is not used to provide contour and bulk, but to cover bone grafts and plates and fill in dead space. Carefully shaped bone grafts provide the correct craniofacial scaffold. Early restoration of a midfacial bony scaffold and the prevention of soft-tissue contraction facilitate secondary reconstruction. Four late total nasal reconstructions with tissue-expanded forehead skin wrapped around bone grafts were performed.     

Pattern of dental development in Hominid XVIII from the Middle Pleistocene Atapuerca-Sima de los Huesos site (Spain)

. We describe the pattern of dental development of Hominid XVIII from the Middle Pleistocene Sima de los Huesos (SH) site of the Sierra de Atapuerca (Burgos, Spain). As expected, this pattern is similar to that of modern humans. A delay of development of the lower and upper canines was observed. In contrast, the relative advanced development of the lower second molars and, especially, the upper and lower third molars is noteworthy. This latter feature seems to be common in Pleistocene hominids, and suggests that the pattern of dental development evolved in the genus Homo during the Pleistocene. In European Middle Pleistocene hominids, this pattern probably was facilitated by the extra space available in the mandible and maxilla for developing teeth.