And yet it moves: Recovery of volitional control after spinal cord injury

Preclinical and clinical neurophysiological and neurorehabilitation research has generated rather surprising levels of recovery of volitional sensory-motor function in persons with chronic motor paralysis following a spinal cord injury. The key factor in this recovery is largely activity-dependent plasticity of spinal and supraspinal networks. This key factor can be triggered by neuromodulation of these networks with electrical and pharmacological interventions. This review addresses some of the systems-level physiological mechanisms that might explain the effects of electrical modulation and how repetitive training facilitates the recovery of volitional motor control. In particular, we substantiate the hypotheses that: (1) in the majority of spinal lesions, a critical number and type of neurons in the region of the injury survive, but cannot conduct action potentials, and thus are electrically non-responsive; (2) these neuronal networks within the lesioned area can be neuromodulated to a transformed state of electrical competency; (3) these two factors enable the potential for extensive activity-dependent reorganization of neuronal networks in the spinal cord and brain, and (4) propriospinal networks play a critical role in driving this activity-dependent reorganization after injury. Real-time proprioceptive input to spinal networks provides the template for reorganization of spinal networks that play a leading role in the level of coordination of motor pools required to perform a given functional task. Repetitive exposure of multi-segmental sensory-motor networks to the dynamics of task-specific sensory input as occurs with repetitive training can functionally reshape spinal and supraspinal connectivity thus re-enabling one to perform complex motor tasks, even years post injury

Scanning tunneling spectroscopy characterization of the pseudogap and the x = 1/8 anomaly in La2-xSrxCuO4 thin films

Using scanning tunneling spectroscopy we examined the local density of states of thin c-axis La2-xSrxCuO4 films, over wide doping and temperature ranges. We found that the pseudogap exists only at doping levels lower than optimal. For x = 0.12, close to the 'anomalous' x = 1/8 doping level, a zero bias conductance peak was the dominant spectral feature, instead of the excepted V- shaped (c-axis tunneling) gap structure. We have established that this surprising effect cannot be explained by tunneling into (110) facets. Possible origins for this unique behavior are discussed.Comment: 15 pages, 6 figure

Acute neuromodulation restores spinally-induced motor responses after severe spinal cord injury

Epidural electrical spinal stimulation can facilitate recovery of volitional motor control in individuals that have been completely paralyzed for more than a year. We recently reported a novel neuromodulation method named Dynamic Stimulation (DS), which short-lastingly increased spinal excitability and generated a robust modulation of locomotor networks in fully-anesthetized intact adult rats. In the present study, we applied repetitive DS patterns to four lumbosacral segments acutely after a contusive injury at lumbar level. Repetitive DS delivery restored the spinally-evoked motor EMG responses that were previously suppressed by a calibrated spinal cord contusion. Sham experiments without DS delivery did not allow any spontaneous recovery. Thus, DS uniquely provides the potential for a greater long-term functional recovery after paralysis

Evidence for Crossed Andreev Reflections in bilayers of (100)YBCO and the itinerant ferromagnet SrRuO3

Scanning tunneling spectroscopy measurements on thin epitaxial SrRuO3/(100)YBCO ferromagnet/superconductor bilayers, reveal localized regions in which the superconductor order parameter penetrates the ferromagnet to more than 26 nm, an order of magnitude larger than the coherence length in the ferromagnetic layer. These regions consist of narrow (< 10 nm) and long strips, separated by at least 200 nm, consistent with the known magnetic domain wall structure in SrRuO3. We attributed this behavior to Crossed Andreev Reflections, taking place in the vicinity of the magnetic domain walls.Comment: submitted to PR

CP Nonconservation in ppˉ→tbˉXp\bar p\to t\bar b X at the Tevatron

The reaction $p\bar p\to t\bar bX$ is found to be rather rich in exhibiting several different types of CP asymmetries. The spin of the top quark plays an important role. Asymmetries are related to form factors arising from radiative corrections of the $tbW$ production vertex due to non-standard physics. As illustrations, effects are studied in two Higgs Doublet Models and in Supersymmetric Models; asymmetries up to a few percent may be possible.Comment: 14 pages, 3 figures. Note: replaced due to minor problems that appeared on some postscript previewers. No change in conten

Semileptonic and nonleptonic B decays to three charm quarks: B->J/psi (eta_c) D l nu and J/psi (eta_c) D pi

We evaluate the form factors describing the semileptonic decays $\bar{B^0}\to J/\psi (\eta_c) D^+ \ell^- \bar \nu_\ell$, within the framework of a QCD relativistic potential model. This decay is complementary to $\bar{B^0}\to J/\psi (\eta_c) D^+ \pi^-$ in a phase space region where a pion factors out.We estimate the branching ratio for these semileptonic and nonleptonic channels, finding $\mathcal{BR}(\bar{B^0} \to J/\psi (\eta_c) D^+ \ell \nu_\ell) \simeq 10^{-13}$, $\mathcal{BR}(\bar{B^0} \to J/\psi D^+ \pi^-) = 3.1 \times 10^{-8}$ and $\mathcal{BR}(\bar{B^0} \to \eta_c D^+ \pi^-) = 3.5 \times 10^{-8}$.Comment: 14 pages, 4 figure

Complete Genome Sequence and Comparative Metabolic Profiling of the Prototypical Enteroaggregative Escherichia coli Strain 042

Background \ud Escherichia coli can experience a multifaceted life, in some cases acting as a commensal while in other cases causing intestinal and/or extraintestinal disease. Several studies suggest enteroaggregative E. coli are the predominant cause of E. coli-mediated diarrhea in the developed world and are second only to Campylobacter sp. as a cause of bacterial-mediated diarrhea. Furthermore, enteroaggregative E. coli are a predominant cause of persistent diarrhea in the developing world where infection has been associated with malnourishment and growth retardation. \ud \ud Methods \ud In this study we determined the complete genomic sequence of E. coli 042, the prototypical member of the enteroaggregative E. coli, which has been shown to cause disease in volunteer studies. We performed genomic and phylogenetic comparisons with other E. coli strains revealing previously uncharacterised virulence factors including a variety of secreted proteins and a capsular polysaccharide biosynthetic locus. In addition, by using Biolog™ Phenotype Microarrays we have provided a full metabolic profiling of E. coli 042 and the non-pathogenic lab strain E. coli K-12. We have highlighted the genetic basis for many of the metabolic differences between E. coli 042 and E. coli K-12. \ud \ud Conclusion \ud This study provides a genetic context for the vast amount of experimental and epidemiological data published thus far and provides a template for future diagnostic and intervention strategies