781 research outputs found
SINGLE SITE ROBOTC DEVICE AND RELATED SYSTEMS AND METHODS
The embodiments disclosed herein relate to various medical device components, including components that can be incor porated into robotic and/or in vivo medical devices. Certain embodiments include various medical devices for in vivo medical procedures
The Pomeron and Gauge/String Duality
The traditional description of high-energy small-angle scattering in QCD has
two components -- a soft Pomeron Regge pole for the tensor glueball, and a hard
BFKL Pomeron in leading order at weak coupling. On the basis of gauge/string
duality, we present a coherent treatment of the Pomeron. In large-N QCD-like
theories, we use curved-space string-theory to describe simultaneously both the
BFKL regime and the classic Regge regime. The problem reduces to finding the
spectrum of a single j-plane Schrodinger operator. For ultraviolet-conformal
theories, the spectrum exhibits a set of Regge trajectories at positive t, and
a leading j-plane cut for negative t, the cross-over point being
model-dependent. For theories with logarithmically-running couplings, one
instead finds a discrete spectrum of poles at all t, where the Regge
trajectories at positive t continuously become a set of slowly-varying and
closely-spaced poles at negative t. Our results agree with expectations for the
BFKL Pomeron at negative t, and with the expected glueball spectrum at positive
t, but provide a framework in which they are unified. Effects beyond the single
Pomeron exchange are briefly discussed.Comment: 68 pages, uses JHEP3.cls, utphys.bst; references added, typos
corrected, and clarifying remarks adde
A Wireless Brain-Machine Interface for Real-Time Speech Synthesis
This is the published version, also available here: http://dx.doi.org/10.1371/journal.pone.0008218.Background
Brain-machine interfaces (BMIs) involving electrodes implanted into the human cerebral cortex have recently been developed in an attempt to restore function to profoundly paralyzed individuals. Current BMIs for restoring communication can provide important capabilities via a typing process, but unfortunately they are only capable of slow communication rates. In the current study we use a novel approach to speech restoration in which we decode continuous auditory parameters for a real-time speech synthesizer from neuronal activity in motor cortex during attempted speech.
Methodology/Principal Findings
Neural signals recorded by a Neurotrophic Electrode implanted in a speech-related region of the left precentral gyrus of a human volunteer suffering from locked-in syndrome, characterized by near-total paralysis with spared cognition, were transmitted wirelessly across the scalp and used to drive a speech synthesizer. A Kalman filter-based decoder translated the neural signals generated during attempted speech into continuous parameters for controlling a synthesizer that provided immediate (within 50 ms) auditory feedback of the decoded sound. Accuracy of the volunteer's vowel productions with the synthesizer improved quickly with practice, with a 25% improvement in average hit rate (from 45% to 70%) and 46% decrease in average endpoint error from the first to the last block of a three-vowel task.
Conclusions/Significance
Our results support the feasibility of neural prostheses that may have the potential to provide near-conversational synthetic speech output for individuals with severely impaired speech motor control. They also provide an initial glimpse into the functional properties of neurons in speech motor cortical areas
A surface-stabilized ozonide triggers bromide oxidation at the aqueous solution-vapour interface
Oxidation of bromide in aqueous environments initiates the formation of molecular halogen compounds, which is important for the global tropospheric ozone budget. In the aqueous bulk, oxidation of bromide by ozone involves a [Br•OOO−] complex as intermediate. Here we report liquid jet X-ray photoelectron spectroscopy measurements that provide direct experimental evidence for the ozonide and establish its propensity for the solution-vapor interface. Theoretical calculations support these findings, showing that water stabilizes the ozonide and lowers the energy of the transition state at neutral pH. Kinetic experiments confirm the dominance of the heterogeneous oxidation route established by this precursor at low, atmospherically relevant ozone concentrations. Taken together, our results provide a strong case of different reaction kinetics and mechanisms of reactions occurring at the aqueous phase-vapor interface compared with the bulk aqueous phase
Dopaminergic Genetic Variants and Voluntary Externally Paced Exercise Behavior
PURPOSE: Most candidate gene studies on the neurobiology of voluntary exercise behavior have focused on the dopaminergic signaling pathway and its role in the mesolimbic reward system. We hypothesized that dopaminergic candidate genes may influence exercise behavior through additional effects on executive functioning and that these effects are only detected when the types of exercise activity are taken into account. METHODS: Data on voluntary exercise behavior and at least one SNP/VNTR were available for 12,929 participants of the Netherlands Twin Registry. Exercise activity was classified as externally paced if a high level of executive function skill was required. The total volume of voluntary exercise (minutes per week) as well as the volume specifically spent on externally paced activities were tested for association with nine functional dopaminergic polymorphisms (DRD1: rs265981, DRD2/ANKK1: rs1800497, DRD3: rs6280, DRD4: VNTR 48bp, DRD5: VNTR 130-166bp, DBH: rs2519152, DAT1: VNTR 40bp, COMT: rs4680, MAOA: VNTR 30bp), a polygenic score (PGS) based on nine alleles leading to lower dopamine responsiveness, and a PGS based on three alleles associated with both higher reward sensitivity and better executive functioning (DRD2/ANKK1: 'G' allele, COMT: Met allele, DAT1: 440bp allele). RESULTS: No association with total exercise volume or externally paced exercise volume was found for individual alleles or the nine-allele polygenic score. The volume of externally paced exercise behavior was significantly associated with the reward and executive function congruent PGS. This association was driven by the DAT1 440bp and COMT Met allele which acted as increaser alleles for externally paced exercise behavior. CONCLUSION: Taking into account the types of exercise activity may increase the success of identifying genetic variants and unraveling the neurobiology of voluntary exercise behavior. Key words: candidate gene, exercise behavior, reward sensitivity, executive functioning
A Wireless Brain-Machine Interface for Real-Time Speech Synthesis
Background: Brain-machine interfaces (BMIs) involving electrodes implanted into the human cerebral cortex have recently been developed in an attempt to restore function to profoundly paralyzed individuals. Current BMIs for restoring communication can provide important capabilities via a typing process, but unfortunately they are only capable of slow communication rates. In the current study we use a novel approach to speech restoration in which we decode continuous auditory parameters for a real-time speech synthesizer from neuronal activity in motor cortex during attempted speech.
Methodology/Principal Findings: Neural signals recorded by a Neurotrophic Electrode implanted in a speech-related region of the left precentral gyrus of a human volunteer suffering from locked-in syndrome, characterized by near-total paralysis with spared cognition, were transmitted wirelessly across the scalp and used to drive a speech synthesizer. A Kalman filter-based decoder translated the neural signals generated during attempted speech into continuous parameters for controlling a synthesizer that provided immediate (within 50 ms) auditory feedback of the decoded sound. Accuracy of the volunteer's vowel productions with the synthesizer improved quickly with practice, with a 25% improvement in average hit rate (from 45% to 70%) and 46% decrease in average endpoint error from the first to the last block of a three-vowel task.
Conclusions/Significance: Our results support the feasibility of neural prostheses that may have the potential to provide near-conversational synthetic speech output for individuals with severely impaired speech motor control. They also provide an initial glimpse into the functional properties of neurons in speech motor cortical areas.National Institute on Deafness and Other Communication Disorders (U.S.) (Grant R44-DC007050)National Institute on Deafness and Other Communication Disorders (U.S.) (Grant R01-DC007683)National Institute on Deafness and Other Communication Disorders (U.S.) (Grant R01-DC002852)Center of Excellence for Learning in Education, Science, and Technology (SBE-0354378
Implementation of a politically initiated national clinical guideline for cardiac rehabilitation in hospitals and municipalities in Denmark
A politically initiated national clinical guideline was launched in Denmark in 2013 to improve quality and equality of cardiac rehabilitation (CR) services. The guideline is to be implemented in both hospital and community (municipality) settings due to shared responsibility for provision of CR services. Little is known about implementation outcomes of a guideline in these two settings. We aimed to study this by determining the extent to which Danish CR services in hospitals and municipalities adhered to national recommendations following the launch of the guideline. The study employed an observational, longitudinal design. Data were gathered by a questionnaire survey to compare CR services at baseline, measured in 2013 immediately before the guideline was launched, with CR services at a two-year follow up in 2015. All Danish hospital departments offering CR services (N = 36) and all municipalities (N = 98) were included. Data were analysed using inferential statistics. Hospitals reported improvement of both content and quality of CR services. Municipalities reported no change in content of services, and lower level of fulfilment of one quality aspect. The results suggest that the guideline had different impact in hospitals and municipalities and that the differences in content and quality of services between the two settings increased in the study period, thus contradicting the guidelines´ aim of uniform, evidence-based content of CR services across settings
Testbeds for Transition Metal Dichalcogenide Photonics: Efficacy of Light Emission Enhancement in Monomer vs. Dimer Nanoscale Antennae
Monolayer transition metal dichalcogenides are uniquely-qualified materials
for photonics because they combine well defined tunable direct band gaps and
selfpassivated surfaces without dangling bonds. However, the atomic thickness
of these 2D materials results in low photo absorption limiting the achievable
photo luminescence intensity. Such emission can, in principle, be enhanced via
nanoscale antennae resulting in; a. an increased absorption cross-section
enhancing pump efficiency, b. an acceleration of the internal emission rate via
the Purcell factor mainly by reducing the antennas optical mode volume beyond
the diffraction limit, and c. improved impedance matching of the emitter dipole
to the freespace wavelength. Plasmonic dimer antennae show orders of magnitude
hot-spot field enhancements when an emitter is positioned exactly at the
midgap. However, a 2D material cannot be grown, or easily transferred, to
reside in mid-gap of the metallic dimer cavity. In addition, a spacer layer
between the cavity and the emissive material is required to avoid non-radiative
recombination channels. Using both computational and experimental methods, in
this work we show that the emission enhancement from a 2D emitter- monomer
antenna cavity system rivals that of dimers at much reduced lithographic
effort. We rationalize this finding by showing that the emission enhancement in
dimer antennae does not specifically originate from the gap of the dimer
cavity, but is an average effect originating from the effective cavity
crosssection taken below each optical cavity where the emitting 2D film is
located. In particular, we test an array of different dimer and monomer antenna
geometries and observe a representative 3x higher emission for both monomer and
dimer cavities as compared to intrinsic emission of Chemical Vapor Deposition
synthesized WS2 flakes.Comment: 31 pages, 5 figure
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