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71.
Hochberg LR Serruya MD Friehs GM Mukand JA Saleh M Caplan AH Branner A Chen D Penn RD Donoghue JP 《Nature》2006,442(7099):164-171
Neuromotor prostheses (NMPs) aim to replace or restore lost motor functions in paralysed humans by routeing movement-related signals from the brain, around damaged parts of the nervous system, to external effectors. To translate preclinical results from intact animals to a clinically useful NMP, movement signals must persist in cortex after spinal cord injury and be engaged by movement intent when sensory inputs and limb movement are long absent. Furthermore, NMPs would require that intention-driven neuronal activity be converted into a control signal that enables useful tasks. Here we show initial results for a tetraplegic human (MN) using a pilot NMP. Neuronal ensemble activity recorded through a 96-microelectrode array implanted in primary motor cortex demonstrated that intended hand motion modulates cortical spiking patterns three years after spinal cord injury. Decoders were created, providing a 'neural cursor' with which MN opened simulated e-mail and operated devices such as a television, even while conversing. Furthermore, MN used neural control to open and close a prosthetic hand, and perform rudimentary actions with a multi-jointed robotic arm. These early results suggest that NMPs based upon intracortical neuronal ensemble spiking activity could provide a valuable new neurotechnology to restore independence for humans with paralysis. 相似文献
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Benson JD Chen YN Cornell-Kennon SA Dorsch M Kim S Leszczyniecka M Sellers WR Lengauer C 《Nature》2006,441(7092):451-456
A cancer drug target is only truly validated by demonstrating that a given therapeutic agent is clinically effective and acts through the target against which it was designed. Nevertheless, it is desirable to declare an early-stage drug target as 'validated' before investing in a full-scale drug discovery programme dedicated to it. Although the outcome of validation studies can guide cancer research programmes, strictly defined universal validation criteria have not been established. 相似文献
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中国西南地区地壳运动的GPS监测 总被引:31,自引:0,他引:31
通过1991 ̄1997年期间对中国西南地区GPS(全球定位系统)载波相位测量,建立了青藏高原东部及相邻地区现代地壳运动的速度场,相对于成都,川滇地块及其以西的速度大多为5 ̄10mm/a,鲜水河-小江断裂以东的川青地块和扬子地块运动微弱,约为0 ̄7mm/a,2个地区都表现为顺时钟的涡旋运动,而没有明显的地壳物质向东挤出或逃逸,地壳变形主要型式为顺时针旋卷构造和块体边界断裂的非均一滑动。 相似文献
77.
Bakolitsa C Cohen DM Bankston LA Bobkov AA Cadwell GW Jennings L Critchley DR Craig SW Liddington RC 《Nature》2004,430(6999):583-586
Vinculin is a highly conserved intracellular protein with a crucial role in the maintenance and regulation of cell adhesion and migration. In the cytosol, vinculin adopts a default autoinhibited conformation. On recruitment to cell-cell and cell-matrix adherens-type junctions, vinculin becomes activated and mediates various protein-protein interactions that regulate the links between F-actin and the cadherin and integrin families of cell-adhesion molecules. Here we describe the crystal structure of the full-length vinculin molecule (1,066 amino acids), which shows a five-domain autoinhibited conformation in which the carboxy-terminal tail domain is held pincer-like by the vinculin head, and ligand binding is regulated both sterically and allosterically. We show that conformational changes in the head, tail and proline-rich domains are linked structurally and thermodynamically, and propose a combinatorial pathway to activation that ensures that vinculin is activated only at sites of cell adhesion when two or more of its binding partners are brought into apposition. 相似文献
78.
Pack-MULE transposable elements mediate gene evolution in plants 总被引:2,自引:0,他引:2
79.
Laurance WF Oliveira AA Laurance SG Condit R Nascimento HE Sanchez-Thorin AC Lovejoy TE Andrade A D'Angelo S Ribeiro JE Dick CW 《Nature》2004,428(6979):171-175
Amazonian rainforests are some of the most species-rich tree communities on earth. Here we show that, over the past two decades, forests in a central Amazonian landscape have experienced highly nonrandom changes in dynamics and composition. Our analyses are based on a network of 18 permanent plots unaffected by any detectable disturbance. Within these plots, rates of tree mortality, recruitment and growth have increased over time. Of 115 relatively abundant tree genera, 27 changed significantly in population density or basal area--a value nearly 14 times greater than that expected by chance. An independent, eight-year study in nearby forests corroborates these shifts in composition. Contrary to recent predictions, we observed no increase in pioneer trees. However, genera of faster-growing trees, including many canopy and emergent species, are increasing in dominance or density, whereas genera of slower-growing trees, including many subcanopy species, are declining. Rising atmospheric CO2 concentrations may explain these changes, although the effects of this and other large-scale environmental alterations remain uncertain. These compositional changes could have important impacts on the carbon storage, dynamics and biota of Amazonian forests. 相似文献
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