Mechanism, dynamics, and biological existence of multistability in a large class of bursting neurons

Multistability, the coexistence of multiple attractors in a dynamical system, is explored in bursting nerve cells. A modeling study is performed to show that a large class of bursting systems, as defined by a shared topology when represented as dynamical systems, is inherently suited to support multistability. We derive the bifurcation structure and parametric trends leading to multistability in these systems. Evidence for the existence of multirhythmic behavior in neurons of the aquatic mollusc Aplysia californica that is consistent with our proposed mechanism is presented. Although these experimental results are preliminary, they indicate that single neurons may be capable of dynamically storing information for longer time scales than typically attributed to nonsynaptic mechanisms.Comment: 24 pages, 8 figure

Potentiating paired corticospinal-motoneuronal plasticity after spinal cord injury.

Background: Paired corticospinal-motoneuronal stimulation (PCMS) increases corticospinal transmission in humans with chronic incomplete spinal cord injury (SCI).Objective/Hypothesis: Here, we examine whether increases in the excitability of spinal motoneurons, by performing a voluntary activity, could potentiate PCMS effects on corticospinal transmission.Methods: During PCMS, we used 100 pairs of stimuli where corticospinal volleys evoked by transcranial magnetic stimulation (TMS) over the hand representation of the primary motor cortex were timed to arrive at corticospinal-motoneuronal synapses of the first dorsal interosseous (FDI) muscle ~1e2msbefore antidromic potentials were elicited in motoneurons by electrical stimulation of the ulnar nerve. PCMS was applied at rest (PCMSrest) and during a small level of isometric index finger abduction(PCMSactive) on separate days. Motor evoked potentials (MEPs) elicited by TMS and electrical stimulation were measured in the FDI muscle before and after each protocol in humans with and without (controls)chronic cervical SCI. Results: We found in control participants that MEPs elicited by TMS and electrical stimulation increased to a similar extent after both PCMS protocols for ~30 min. Whereas, in humans with SCI, MEPs elicited by TMS and electrical stimulation increased to a larger extent after PCMSactivecompared with PCMSrest.Importantly, SCI participants who did not respond to PCMSrestresponded after PCMSactiveand those who responded to both protocols showed larger increments in corticospinal transmission after PCMSactive.Conclusions: Our findings suggest that muscle contraction during PCMS potentiates corticospinal transmission. PCMS applied during voluntary activity may represent a strategy to boost spinal plasticity after SCI

Robust Passivity-Based Control of Boost Converters in DC Microgrids

This work deals with the design of a robust and decentralized passivity-based control scheme for regulating the voltage of a DC microgrid through boost converters. A Krasovskii-type storage function is proposed and a (local) passivity property for DC microgrids comprising unknown 'ZIP' (constant impedance 'Z', constant current 'I' and constant power 'P') loads is established. More precisely, the input port-variable of the corresponding passive map is equal to the first-time derivative of the control input. Then, the integrated input port-variable is used to shape the closed loop storage function such that it has a minimum at the desired equilibrium point. Convergence to the desired equilibrium is theoretically analyzed and the proposed control scheme is validated through experiments on a real DC microgrid

Future scenarios of risk of Vibrio infections in a warming planet: a global mapping study

Background: Infections caused by non-cholera Vibrio species have undergone a global expansion over the past few decades reaching new areas of the world that were previously considered adverse for these organisms. The geographical extent of the expansion has not been uniform, and some areas have shown a rapid increase in infections. Methods: We applied a new generation of models combining climate, population, and socioeconomic projections to map future scenarios of distribution and season suitability for pathogenic Vibrio. We used the Coupled Model Intercomparison Project 6 framework. Three datasets were used: Geophysical Fluid Dynamics Laboratory's CM4.0 sea surface temperature and sea surface salinity; the coastline length dataset from the World Resources Institute; and Inter-Sectoral Impact Model Intercomparison Project 2b annual global population data. Future projections were used up to the year 2100 and historical simulations from 1850 to 2014. We also project human population at risk under different shared socioeconomic pathways worldwide. Findings: Projections showed that coastal areas suitable for Vibrio could cover 38 000 km of new coastal areas by 2100 under the most unfavourable scenario with an expansion rate of season suitability in these regions of around 1 month every 30 years. Population at risk in suitable regions almost doubled from 1980 to 2020 (from 610 million to 1100 million under the scenario of medium challenges to mitigation and adaptation, shared socioeconomic pathway 2-4.5), although the increment will be more moderate in the future and stabilises after 2050 at 1300 million. Finally, we provide the first global estimate for Vibrio infections, with values around half a million of cases worldwide in 2020. Interpretation: Our projections anticipated an expansion of both the temporal and spatial disease burden for Vibrio infections, in particular at high latitudes of the northern hemisphere. However, the largest extent occurred from 1980 to 2020 and a more moderate increase is expected for the future. The most positive outcome is that the projections showed that Vibrio morbidity will remain relatively stable over the coming decades. Funding: NOAA Atlantic Oceanographic and Meteorological Laboratory and NOAA OceanWatch, and by the University of Miami's Cooperative Institute for Marine and Atmospheric StudiesS

Semi-Resistive Approach for Tightly Coupled Dipole Array Bandwidth Enhancement

A new approach to enhance the bandwidth of Tightly Coupled Dipole Arrays (TCDA) is presented. The new design achieves the integration of a semi-resistive Frequency Selective Surface network (FSS) composed of a non-resistive low-pass FSS and two resistive band-stop FSSs. The integration of this FSS network within a dual-polarized Tightly Coupled Dipole Array (TCDA) led to an increased impedance bandwidth of 28:1 from 0.20GHz to 5.6GHz. Notably, the use of an FSS superstrate allowed for scanning down to 60° at VSWR \u3c 3 in the E-plane and VSWR \u3c 4 in the D- and H-planes. Additionally, the strategic use of the inserted low-pass FSS reduces the resistive effects above 2.5GHz for improved average efficiency. A array prototype was fabricated and tested to verify the bandwidth and gain of a finite array. The simulated radiation efficiency was demonstrated to be 83%, on average, across the band

Technology, governance, and a sustainability model for small and medium-sized towns in Europe

New and cutting-edge technologies causing deep changes in societies, playing the role of game modifiers, and having a significant impact on global markets in small and medium-sized towns in Europe (SMSTEs) are the focus of this research. In this context, an analysis was carried out to identify the main dimensions of a model for promoting innovation in SMSTEs. The literature review on the main dimensions boosting the innovation in SMSTEs and the methodological approach was the application of a survey directed to experts on this issue. The findings from the literature review reflect that technologies, governance, and sustainability dimensions are enablers of SMSTEs’ innovation, and based on the results of the survey, a model was implemented to boost innovation, being this the major add-on of this research.info:eu-repo/semantics/publishedVersio

Low-Cost S-Band Reconfigurable Monopole/Patch Antenna for CubeSats

The development of reconfigurable antennas compatible with a CubeSat form factor can aid several space missions. Often, satellite missions require multiple wireless links with the same radio, but the design of such antennas is challenging due to the mechanical constraints and the limited power aboard a CubeSat. In this article, we present a unique reconfigurable antenna concept enabled by adhesive polyimide tapes. The presented antenna can switch from a conventional patch to a monopole-like antenna with minimal actuation complexity. This reconfiguration provides choices for polarization, pattern, and gain without use of active components for size, cost and power consumption reductions. The frequency of operation is S-band (2.4 GHz), and the antenna achieves S_{11} \u3c -10 dB for both reconfiguration states. Measurements compare well with simulations in both states

Effects of Inter-Stimulus Interval on Speech-Evoked Frequency-Following Response in Elderly Adults

Background: The speech-evoked frequency following response (FFR) has shown to be useful in assessing complex auditory processing abilities and in different age groups. While many aspects of FFR have been studied extensively, the effect of timing, as measured by inter-stimulus-interval (ISI), especially in the older adult population, has yet to be thoroughly investigated. Objective: The purpose of this study was to examine the effects of different ISIs on speech evoked FFR in older and younger adults who speak a tonal language, and to investigate whether the older adults’ FFR were more susceptible to the change in ISI. Materials and Methods: Twenty-two normal hearing participants were recruited in our study, including 11 young adult participants and 11 elderly participants. An Intelligent Hearing Systems Smart EP evoke potential system was used to record the FFR in four ISI conditions (40, 80, 120 and 160 ms). A recorded natural speech token with a falling tone /yi/ was used as the stimulus. Two indices, stimulus-to-response correlation coefficient and pitch strength, were used to quantify the FFR responses. Two-way analysis of variance (ANOVA) was used to analyze the differences in different age groups and different ISI conditions. Results: There was no significant difference in stimulus-to-response correlation coefficient and pitch strength among the different ISI conditions, in either age groups. Older adults appeared to have weaker FFR for all ISI conditions when compared to their younger adult counterparts. Conclusion: Shorter ISIs did not result in worse FFRs from older adults or younger adults. For speech-evoked FFR using a recorded natural speech token that is 250 ms in length, an ISI of as short as 40 ms appeared to be sufficient and effective to record FFR for elderly adults

Cooperative Authentication in Underwater Acoustic Sensor Networks

With the growing use of underwater acoustic communications (UWAC) for both industrial and military operations, there is a need to ensure communication security. A particular challenge is represented by underwater acoustic networks (UWANs), which are often left unattended over long periods of time. Currently, due to physical and performance limitations, UWAC packets rarely include encryption, leaving the UWAN exposed to external attacks faking legitimate messages. In this paper, we propose a new algorithm for message authentication in a UWAN setting. We begin by observing that, due to the strong spatial dependency of the underwater acoustic channel, an attacker can attempt to mimic the channel associated with the legitimate transmitter only for a small set of receivers, typically just for a single one. Taking this into account, our scheme relies on trusted nodes that independently help a sink node in the authentication process. For each incoming packet, the sink fuses beliefs evaluated by the trusted nodes to reach an authentication decision. These beliefs are based on estimated statistical channel parameters, chosen to be the most sensitive to the transmitter-receiver displacement. Our simulation results show accurate identification of an attacker's packet. We also report results from a sea experiment demonstrating the effectiveness of our approach.Comment: Author version of paper accepted for publication in the IEEE Transactions on Wireless Communication