60 research outputs found
Perspectives on Highly Adaptive or Morphing Aircraft
The ability to adapt to different flight conditions has been fundamental to aircraft design since the Wright Brothers first flight. Over a hundred years later, unconventional aircraft adaptability, often called aircraft morphing has become a topic of considerable renewed interest. In the past two decades, this interest has been largely fuelled by advancements in multi-functional or smart materials and structures. However, highly adaptive or morphing aircraft is certainly a cross-discipline challenge that stimulates a wide range of design possibilities. This paper will review some of the history of morphing aircraft including recent research programs and discuss some perspectives on this work
Orion Crew Exploration Vehicle Launch Abort System Guidance and Control Analysis Overview
Aborts during the critical ascent flight phase require the design and operation of Orion Crew Exploration Vehicle (CEV) systems to escape from the Crew Launch Vehicle (CLV) and return the crew safely to the Earth. To accomplish this requirement of continuous abort coverage, CEV ascent abort modes are being designed and analyzed to accommodate the velocity, altitude, atmospheric, and vehicle configuration changes that occur during ascent. Aborts from the launch pad to early in the flight of the CLV second stage are performed using the Launch Abort System (LAS). During this type of abort, the LAS Abort Motor is used to pull the Crew Module (CM) safely away from the CLV and Service Module (SM). LAS abort guidance and control studies and design trades are being conducted so that more informed decisions can be made regarding the vehicle abort requirements, design, and operation. This paper presents an overview of the Orion CEV, an overview of the LAS ascent abort mode, and a summary of key LAS abort analysis methods and results
Psychedelics in developmental stuttering to modulate brain functioning: a new therapeutic perspective?
Developmental stuttering (DS) is a neurodevelopmental speech-motor disorder characterized by symptoms such as blocks, repetitions, and prolongations. Persistent DS often has a significant negative impact on quality of life, and interventions for it have limited efficacy. Herein, we briefly review existing research on the neurophysiological underpinnings of DS -specifically, brain metabolic and default mode/social-cognitive networks (DMN/SCN) anomalies- arguing that psychedelic compounds might be considered and investigated (e.g., in randomized clinical trials) for treatment of DS. The neural background of DS is likely to be heterogeneous, and some contribution from genetically determinants of metabolic deficiencies in the basal ganglia and speech-motor cortical regions are thought to play a role in appearance of DS symptoms, which possibly results in a cascade of events contributing to impairments in speech-motor execution. In persistent DS, the difficulties of speech are often linked to a series of associated aspects such as social anxiety and social avoidance. In this context, the SCN and DMN (also influencing a series of fronto-parietal, somato-motor, and attentional networks) may have a role in worsening dysfluencies. Interestingly, brain metabolism and SCN/DMN connectivity can be modified by psychedelics, which have been shown to improve clinical evidence of some psychiatric conditions (e.g., depression, post-traumatic stress disorder, etc.) associated with psychological constructs such as rumination and social anxiety, which also tend to be present in persistent DS. To date, while there have been no controlled trials on the effects of psychedelics in DS, anecdotal evidence suggests that these agents may have beneficial effects on stuttering and its associated characteristics. We suggest that psychedelics warrant investigation in DS
Prediction of rehabilitation induced motor recovery after stroke using a multi-dimensional and multi-modal approach
Background: Stroke is a debilitating disease affecting millions of people worldwide. Despite the survival rate has significantly increased over the years, many stroke survivors are left with severe impairments impacting their quality of life. Rehabilitation programs have proved to be successful in improving the recovery process. However, a reliable model of sensorimotor recovery and a clear identification of predictive markers of rehabilitation-induced recovery are still needed. This article introduces the cross-modality protocols designed to investigate the rehabilitation treatment’s effect in a group of stroke survivors. Methods/design: A total of 75 stroke patients, admitted at the IRCCS San Camillo rehabilitation Hospital in Venice (Italy), will be included in this study. Here, we describe the rehabilitation programs, clinical, neuropsychological, and physiological/imaging [including electroencephalography (EEG), transcranial magnetic stimulation (TMS), and magnetic resonance imaging (MRI) techniques] protocols set up for this study. Blood collection for the characterization of predictive biological biomarkers will also be taken. Measures derived from data acquired will be used as candidate predictors of motor recovery. Discussion/summary: The integration of cutting-edge physiological and imaging techniques, with clinical and cognitive assessment, dose of rehabilitation and biological variables will provide a unique opportunity to define a predictive model of recovery in stroke patients. Taken together, the data acquired in this project will help to define a model of rehabilitation induced sensorimotor recovery, with the final aim of developing personalized treatments promoting the greatest chance of recovery of the compromised functions
Single-molecule correlated chemical probing of RNA
RNA molecules function as the central conduit of information transfer in biology. To do this, they encode information both in their sequences and in their higher-order structures. Understanding the higher-order structure of RNA remains challenging. In this work we devise a simple, experimentally concise, and accurate approach for examining higher-order RNA structure by converting widely used massively parallel sequencing into an easily implemented single-molecule experiment for detecting through-space interactions and multiple conformations. We then use this experiment to analyze higher-order RNA structure, detect biologically important hidden states, and refine accurate three-dimensional structure models
Intercontinental optical clock comparison using the geodetic VLBI technique in K-band
Comparing distant atomic clocks is very important for international timekeeping, global positioning and tests of fundamental physics. Optical clocks
are the most technologically advanced devices for frequency generation with a stability of 10−18. In the near future they could be used in the redefinition of the SI
second replacing the current one defined using the microwave transition of a Cs atom. Optical fiber link networks allow the most performing optical clocks to be
compared on distances up to two thousand kilometers,
but for longer distances clock comparisons are limited by the performances of satellite frequency transfer techniques. In this presentation we show the use
of high-frequency geodetic VLBI as an alternative technique for long distance frequency transfer. A K-band
24-hour experiment involving six antennas between Europe and Korea was carried out in order to estimate the clock rate between the H-masers of Medicina and KRISS sites. These masers were connected and
calibrated against two Ytterbium lattice optical clocks
in INRiM (Italy) and KRISS (Korea). The fractional frequency difference between the optical clocks was thus
evaluated
Dynamic Visuomotor Transformation Involved with Remote Flying of a Plane Utilizes the ‘Mirror Neuron’ System
Brain regions involved with processing dynamic visuomotor representational transformation are investigated using fMRI. The perceptual-motor task involved flying (or observing) a plane through a simulated Red Bull Air Race course in first person and third person chase perspective. The third person perspective is akin to remote operation of a vehicle. The ability for humans to remotely operate vehicles likely has its roots in neural processes related to imitation in which visuomotor transformation is necessary to interpret the action goals in an egocentric manner suitable for execution. In this experiment for 3rd person perspective the visuomotor transformation is dynamically changing in accordance to the orientation of the plane. It was predicted that 3rd person remote flying, over 1st, would utilize brain regions composing the ‘Mirror Neuron’ system that is thought to be intimately involved with imitation for both execution and observation tasks. Consistent with this prediction differential brain activity was present for 3rd person over 1st person perspectives for both execution and observation tasks in left ventral premotor cortex, right dorsal premotor cortex, and inferior parietal lobule bilaterally (Mirror Neuron System) (Behaviorally: 1st>3rd). These regions additionally showed greater activity for flying (execution) over watching (observation) conditions. Even though visual and motor aspects of the tasks were controlled for, differential activity was also found in brain regions involved with tool use, motion perception, and body perspective including left cerebellum, temporo-occipital regions, lateral occipital cortex, medial temporal region, and extrastriate body area. This experiment successfully demonstrates that a complex perceptual motor real-world task can be utilized to investigate visuomotor processing. This approach (Aviation Cerebral Experimental Sciences ACES) focusing on direct application to lab and field is in contrast to standard methodology in which tasks and conditions are reduced to their simplest forms that are remote from daily life experience
A Global Fireball Observatory
The world's meteorite collections contain a very rich picture of what the
early Solar System would have been made of, however the lack of spatial context
with respect to their parent population for these samples is an issue. The
asteroid population is equally as rich in surface mineralogies, and mapping
these two populations (meteorites and asteroids) together is a major challenge
for planetary science. Directly probing asteroids achieves this at a high cost.
Observing meteorite falls and calculating their pre-atmospheric orbit on the
other hand, is a cheaper way to approach the problem. The Global Fireball
Observatory (GFO) collaboration was established in 2017 and brings together
multiple institutions (from Australia, USA, Canada, Morocco, Saudi Arabia, the
UK, and Argentina) to maximise the area for fireball observation time and
therefore meteorite recoveries. The members have a choice to operate
independently, but they can also choose to work in a fully collaborative manner
with other GFO partners. This efficient approach leverages the experience
gained from the Desert Fireball Network (DFN) pathfinder project in Australia.
The state-of-the art technology (DFN camera systems and data reduction) and
experience of the support teams is shared between all partners, freeing up time
for science investigations and meteorite searching. With all networks combined
together, the GFO collaboration already covers 0.6% of the Earth's surface for
meteorite recovery as of mid-2019, and aims to reach 2% in the early 2020s. We
estimate that after 5 years of operation, the GFO will have observed a fireball
from virtually every meteorite type. This combined effort will bring new,
fresh, extra-terrestrial material to the labs, yielding new insights about the
formation of the Solar System.Comment: Accepted in PSS. 19 pages, 9 figure
Image Reconstruction Scheme for Watersheds based Video Segmentation HyunSil Shin
Abstract- In this paper, we proposed a new solution to the reconstruction of image in order to solve the oversegmentation problem of watershed transformation which is widely used as an image segmentation method. The process for reconstruction of image consists of consolidation of edges and removal of local minima. The former(consolidation of edges) enhances the edge between the object in image background and the other(removal of local minima) erodes partially an image in order to eliminate the small local minima. Comparing to the existing solution, the proposed method could efficiently solve the over-segmentation problem within a very short time. And, using the modified similarity measure, we could acquire the result which is independently merged even though the criterion area is different. So, our result can be applied real-time video based application such as video conference, surveillance and MPEG-4 based systems
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