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排序方式: 共有159条查询结果,搜索用时 171 毫秒
151.
Luca Ascari Ulisse Bertocchi Paolo Corradi Cecilia Laschi Paolo Dario 《Biological cybernetics》2009,100(2):109-128
The capability of grasping and lifting an object in a suitable, stable and controlled way is an outstanding feature for a
robot, and thus far, one of the major problems to be solved in robotics. No robotic tools able to perform an advanced control
of the grasp as, for instance, the human hand does, have been demonstrated to date. Due to its capital importance in science
and in many applications, namely from biomedics to manufacturing, the issue has been matter of deep scientific investigations
in both the field of neurophysiology and robotics. While the former is contributing with a profound understanding of the dynamics
of real-time control of the slippage and grasp force in the human hand, the latter tries more and more to reproduce, or take
inspiration by, the nature’s approach, by means of hardware and software technology. On this regard, one of the major constraints
robotics has to overcome is the real-time processing of a large amounts of data generated by the tactile sensors while grasping,
which poses serious problems to the available computational power. In this paper a bio-inspired approach to tactile data processing
has been followed in order to design and test a hardware–software robotic architecture that works on the parallel processing
of a large amount of tactile sensing signals. The working principle of the architecture bases on the cellular nonlinear/neural
network (CNN) paradigm, while using both hand shape and spatial–temporal features obtained from an array of microfabricated
force sensors, in order to control the sensory-motor coordination of the robotic system. Prototypical grasping tasks were
selected to measure the system performances applied to a computer-interfaced robotic hand. Successful grasps of several objects,
completely unknown to the robot, e.g. soft and deformable objects like plastic bottles, soft balls, and Japanese tofu, have
been demonstrated. 相似文献
152.
Maria L. Corradi da Silva Diego T.D. Exposti Ana F.D. Vasconcelos Samara M.A. Alexandre Joana L.M. Silveira Diogo R.B. Ducatti 《Carbohydrate polymers》2013
A water-soluble polysaccharide was extracted with alkali from the cell wall of Verticillium lecanii (also called Lecanicillium lecanii). After freezing and thawing, the water-soluble fraction was purified by gel filtration chromatography on Sepharose CL-6B and eluted as one peak by HPSEC/RID. Monosaccharide analysis showed galactose and glucose (1.1:1), with traces of mannose (<1%). The structural characteristics were determined by spectroscopic analysis, FT-IR and 1D and 2D 1H and 13C NMR, and methylation results. On the basis of the data obtained, the following structure of the polysaccharide (E3SIV fraction) was established: 相似文献
153.
We report the genome sequence of a healthcare-associated MRSA type ST239 clone isolated from a patient with septicemia in Malaysia. This clone typifies the characteristics of ST239 lineage, including resistance to multiple antibiotics and antiseptics. 相似文献
154.
Cholecystokinin (CCK) belongs to the group of substances known as brain-gut peptides: it functions both as a neuropeptide and a gut hormone. The peptide and its synthetic derivatives (like for instance CCK-8 and the amphibian counterpart caerulein) significantly delay emptying of gastric contents in both animals and humans. The fact that CCK, in doses mimicking postprandial plasma levels, strongly affects emptying rate suggests the peptide to be a physiologic regulator of gastric emptying. Unfortunately, clear definition of the role of CCK in the physiology of gastric motor activity has long been hampered by the lack of specific and potent non-peptide antagonists of CCK-receptors. The availability of such compounds has stimulated a broad array of investigations into the physiological actions of this hormone and examination of its putative role in certain diseases. This paper summarizes the available data concerning the effect of CCK and its antagonists on gastric emptying. The use of selective CCK-antagonists has allowed to establish that the gastric motor effect of the peptide is direct and mediated through the stimulation of CCK-A receptors. As a consequence, CCK-A antagonism results in acceleration of emptying rate under certain experimental and clinical conditions. This peculiar pharmacologic effect of CCK-A antagonists, which could be useful in the treatment of functional dyspepsia (idiopathic or diabetic), gastroparesis and gastro-esophageal reflux disease (where patients often display a delayed emptying rate of solid food) needs to be further investigated, in order to fully explore their potential as gastrokinetic drugs. 相似文献
155.
156.
Jeremías Corradi 《Biophysical journal》2009,97(5):1335-1345
The 5-HT3A receptor is a member of the Cys-loop family of ligand-gated ion channels. To perform kinetic analysis, we mutated the 5-HT3A subunit to obtain a high-conductance form so that single-channel currents can be detected. At all 5-HT concentrations (>0.1 μM), channel activity appears as openings in quick succession that form bursts, which coalesce into clusters. By combining single-channel and macroscopic data, we generated a kinetic model that perfectly describes activation, deactivation, and desensitization. The model shows that full activation arises from receptors with three molecules of agonist bound. It reveals an earlier conformational change of the fully liganded receptor that occurs while the channel is still closed. From this pre-open closed state, the receptor enters into an open-closed cycle involving three open states, which form the cluster whose duration parallels the time constant of desensitization. A similar model lacking the pre-open closed state can describe the data only if the opening rates are fixed to account for the slow activation rate. The application of the model to M4 mutant receptors shows that position 10′ contributes to channel opening and closing rates. Thus, our kinetic model provides a foundation for understanding structural bases of activation and drug action. 相似文献
157.
Diana Poli Matteo Goldoni Massimo Corradi Olga Acampa Paolo Carbognani Eveline Internullo Angelo Casalini Antonio Mutti 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2010,878(27):2643-2651
A number of volatile organic compounds (VOCs) have been identified and used in preliminary clinical studies of the early diagnosis of lung cancer. The aim of this study was to evaluate the potential of aldehydes (known biomarkers of oxidative stress) in the diagnosis of patients with non-small cell lung cancer (NSCLC). We used an on-fiber-derivatisation SPME sampling technique coupled with GC/MS analysis to measure straight aldehydes C3–C9 in exhaled breath. Linearity was established over two orders of magnitude (range: 3.3–333.3 × 10−12 M); the LOD and LOQ of all the aldehydes were respectively 1 × 10−12 M and 3 × 10−12 M. Accuracy was within 93% and precision calculated as % RSD was 7.2–15.1%. Aldehyde stability in a Bio-VOC® tube stored at +4 °C was 10–17 h, but this became >10 days using a specific fiber storage device. Finally, exhaled aldehydes were measured in 38 asymptomatic non-smokers (controls) and 40 NSCLC patients. The levels of all of the aldehydes were increased in the NSCLC patients without any significant effect of smoking habits and little effect of age. The good discriminant power of the aldehyde pattern (90%) was confirmed by multivariate analysis. These results show that straight aldehydes may be promising biomarkers associated with NSCLC, and increase the sensitivity and specificity of previously identified VOC patterns. 相似文献
158.
The mammalian accessory olfactory bulb (AOB) is chemoarchitecturally
heterogeneous in that it stains differentially with a number of markers;
the receptor cells that project to the AOB are similarly heterogeneous.
What is the significance of this heterogeneity? We have found that the AOB
of the gray, short-tailed opossum, Monodelphis domestica, stains
differentially with a number of 'markers': antibodies to olfactory marker
protein (OMP) and the alpha subunit of the G protein Gi2, the lectin of
Vicia villosa and NADPH-diaphorase. These markers stain the rostral AOB
more strongly than the caudal AOB whereas, the G protein subunit G(o) alpha
is located predominantly in the posterior subdivision of the AOB. This
heterogeneity in the chemoarchitecture of the AOB may reflect a fundamental
organizational dichotomy within the vomeronasal system that corresponds to
a functional dichotomy. The vomeronasal sensory epithelium also exhibits a
chemoarchitectural heterogeneity: receptor cells in the basal third are
G(o) alpha-immunoreactive whereas the cells in the middle third are Gi2
alpha-immunoreactive. Tracing studies using WGA-HRP demonstrate that the
neurons in the middle third of the vomeronasal sensory epithelium project
their axons to the anterior AOB whereas those in the basal third appear to
project to the posterior AOB.
相似文献
159.