2,048 research outputs found
Spokes cluster: The search for the quiescent gas
Context. Understanding the role of fragmentation is one of the most important
current questions of star formation. To better understand the process of star
and cluster formation, we need to study in detail the physical structure and
properties of the parental molecular cloud. The Spokes cluster, or NGC 2264 D,
is a rich protostellar cluster where previous N2H+(1-0) observations of its
dense cores presented linewidths consistent with supersonic turbulence.
However, the fragmentation of the most massive of these cores appears to have a
scale length consistent with that of the thermal Jeans length, suggesting that
turbulence was not dominant. Aims. These two results probe different density
regimes. Our aim is to determine if there is subsonic or less-turbulent gas
(than previously reported) in the Spokes cluster at higher densities. Methods.
We present APEX N2H+(3-2) and N2D+(3-2) observations of the NGC2264-D region to
measure the linewidths and the deuteration fraction of the higher density gas.
The critical densities of the selected transitions are more than an order of
magnitude higher than that of N2H+(1-0). Results. We find that the N2H+(3-2)
and N2D+(3-2) emission present significantly narrower linewidths than the
emission from N2H+(1-0) for most cores. In two of the spectra, the nonthermal
component is close (within 1-sigma) to the sound speed. In addition, we find
that the three spatially segregated cores, for which no protostar had been
confirmed show the highest levels of deuteration. Conclusions. These results
show that the higher density gas, probed with N2H+ and N2D+(3-2), reveals more
quiescent gas in the Spokes cluster than previously reported. More high-angular
resolution interferometric observations using high-density tracers are needed
to truly assess the kinematics and substructure within NGC2264-D. (Abridged)Comment: 8 pages, 4 figures. Accepted in A&
Behavioral and Electrophysiological Characterization of Induced Neural Plasticity in the Autistic Brain
Sensorimotor cortex as a critical component of an 'extended' mirror neuron system: Does it solve the development, correspondence, and control problems in mirroring?
A core assumption of how humans understand and infer the intentions and beliefs of others is the existence of a functional self-other distinction. At least two neural systems have been proposed to manage such a critical distinction. One system, part of the classic motor system, is specialized for the preparation and execution of motor actions that are self realized and voluntary, while the other appears primarily involved in capturing and understanding the actions of non-self or others. The latter system, of which the mirror neuron system is part, is the canonical action 'resonance' system in the brain that has evolved to share many of the same circuits involved in motor control. Mirroring or 'shared circuit systems' are assumed to be involved in resonating, imitating, and/or simulating the actions of others. A number of researchers have proposed that shared representations of motor actions may form a foundational cornerstone for higher order social processes, such as motor learning, action understanding, imitation, perspective taking, understanding facial emotions, and empathy. However, mirroring systems that evolve from the classic motor system present at least three problems: a development, a correspondence, and a control problem. Developmentally, the question is how does a mirroring system arise? How do humans acquire the ability to simulate through mapping observed onto executed actions? Are mirror neurons innate and therefore genetically programmed? To what extent is learning necessary? In terms of the correspondence problem, the question is how does the observer agent know what the observed agent's resonance activation pattern is? How does the matching of motor activation patterns occur? Finally, in terms of the control problem, the issue is how to efficiently control a mirroring system when it is turned on automatically through observation? Or, as others have stated the problem more succinctly: "Why don't we imitate all the time?" In this review, we argue from an anatomical, physiological, modeling, and functional perspectives that a critical component of the human mirror neuron system is sensorimotor cortex. Not only are sensorimotor transformations necessary for computing the patterns of muscle activation and kinematics during action observation but they provide potential answers to the development, correspondence and control problems
The "True" Column Density Distribution in Star-Forming Molecular Clouds
We use the COMPLETE Survey's observations of the Perseus star-forming region
to assess and intercompare three methods for measuring column density in
molecular clouds: extinction mapping (NIR); thermal emission mapping (FIR); and
mapping the intensity of CO isotopologues. The structures shown by all three
tracers are morphologically similar, but important differences exist.
Dust-based measures give similar, log-normal, distributions for the full
Perseus region, once careful calibration corrections are made. We also compare
dust- and gas-based column density distributions for physically-meaningful
sub-regions of Perseus, and we find significant variations in the distributions
for those regions. Even though we have used 12CO data to estimate excitation
temperatures, and we have corrected for opacity, the 13CO maps seem unable to
give column distributions that consistently resemble those from dust measures.
We have edited out the effects of the shell around the B-star HD 278942. In
that shell's interior and in the parts where it overlaps the molecular cloud,
there appears to be a dearth of 13CO, likely due either to 13CO not yet having
had time to form in this young structure, and/or destruction of 13CO in the
molecular cloud. We conclude that the use of either dust or gas measures of
column density without extreme attention to calibration and artifacts is more
perilous than even experts might normally admit. And, the use of 13CO to trace
total column density in detail, even after proper calibration, is unavoidably
limited in utility due to threshold, depletion, and opacity effects. If one's
main aim is to map column density, then dust extinction seems the best probe.
Linear fits amongst column density tracers are given, quantifying the inherent
uncertainties in using one tracer (when compared with others). [abridged]Comment: Accepted in ApJ. 13 pages, 6 color figures. It includes small changes
to improve clarity. For a version with high-resolution figures see
http://www.cfa.harvard.edu/COMPLETE/papers/Goodman_ColumnDensity.pd
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A Systematic Review of The Potential Use of Neurofeedback in Patients with Schizophrenia.
Schizophrenia (SCZ) is a neurodevelopmental disorder characterized by positive symptoms (hallucinations and delusions), negative symptoms (anhedonia, social withdrawal) and marked cognitive deficits (memory, executive function, and attention). Current mainstays of treatment, including medications and psychotherapy, do not adequately address cognitive symptoms, which are essential for everyday functioning. However, recent advances in computational neurobiology have rekindled interest in neurofeedback (NF), a form of self-regulation or neuromodulation, in potentially alleviating cognitive symptoms in patients with SCZ. Therefore, we conducted a systematic review of the literature for NF studies in SCZ to identify lessons learned and to identify steps to move the field forward. Our findings reveal that NF studies to date consist mostly of case studies and small sample, single-group studies. Despite few randomized clinical trials, the results suggest that NF is feasible and that it leads to measurable changes in brain function. These findings indicate early proof-of-concept data that needs to be followed up by larger, randomized clinical trials, testing the efficacy of NF compared to well thought out placebos. We hope that such an undertaking by the field will lead to innovative solutions that address refractory symptoms and improve everyday functioning in patients with SCZ
La sociologÃa herramienta vital para la alta gerencia del III milenio
Durante toda el texto el lector encontratará una manera sencilla de entender las disciplinas de la sociologÃa y la manera simple de emplearlas en la administración del personal. Lograr entender al hombre y darle la importancia que merece dentro de la organización es la base para lograr hacer de él el recurso más productivo y más valiosos de la organización, debe ser el objetivo que se tracen todos aquellos que tienen la misión de influenciar a otros. En este III milenio donde se ha descubierto que la piedra angular de la administración está en el capital humano no pueden existir gerentes que desconozcan la importancia del estudio del hombre en pro de un cambio hacia el mejoramiento continuo
Advanced Augmentative and Alternative Communication System Based in Physiological Control
Dyskinetic Cerebral Palsy (DCP) is mainly characterized by alterations in muscle tone and involuntary movements. Therefore, these people present with difficulties in coordination and movement control, which makes walking difficult and affects their posture when seated. Additionally, their cognitive performance varies between being completely normal and severe mental retardation.
People with DCP were selected as the objective of this thesis due to their multiple and complex limitations (speech problems and motor control) and because their capabilities have a great margin for improvement thanks to physiological control systems.
Given their communication difficulties, some people with DCP have good motor con-trol and can communicate with written language. However, most have difficulty using Augmentative and Alternative Communication (AAC) systems. People with DCP gen-erally use concept boards to indicate the idea they want to communicate. However, most communication solutions available today are based on proprietary software that makes it difficult to customize the concept board and this type of control system.
This is the motivation behind this thesis, with the aim of creating an interface with characteristics, able to be adapted to the user needs and limitations. Thus, this thesis proposes an Augmentative and Alternative Communication System for people with DCP based on physiological control. In addition, an innovative system for direct con-trol of concept boards with EMG is proposed. This control system is based on a physi-cal model that reproduces the muscular mechanical response (stiffness, inertia and viscosity). It allows for a selection of elements thanks to small pulses of EMG signal with sensors on a muscle with motor control. Its main advantage is the possibility of correcting errors during selection associated with uncontrolled muscle impulses, avoid-ing sustained muscle effort and thus reduced fatigue.La Parálisis Cerebral de tipo Discinésica (DCP) se caracteriza principalmente por las alteraciones del tono muscular y los movimientos involuntarios. Por ello, estos pacientes presentan dificultades en la coordinación y en el control de movimientos, lo cual les dificulta el caminar y afecta su postura cuando están sentados. Cabe resaltar que la capacidad cognitiva de las personas con DCP puede variar desde completamente normal, hasta un retraso mental severo.
Las personas con DCP han sido seleccionadas como objetivo de esta tesis ya el margen de mejora de sus capacidades es amplio gracias a sistemas de control fisiológico, debido a sus múltiples y complejas limitaciones (problemas de habla y control motor).
Debido a sus dificultades de comunicación, algunas personas con DCP se pueden comunicar con lenguaje escrito, siempre y cuando tenga un buen control motor. Sin embargo, la mayorÃa tienen dificultades para usar sistemas de Comunicación Aumentativos y Alternativos (AAC). De hecho, las personas con DCP utilizan generalmente tableros de conceptos para indicar la idea que quieren transmitir. Sin embargo, la mayorÃa las soluciones de comunicación disponibles en la actualidad están basadas en software propietario que hacen difÃcil la personalización del tablero de conceptos y el tipo de sistema de control.
Es aquà donde surge esta tesis, con el objetivo de crear una interfaz con esas caracterÃsticas, capaz de adaptarse a las necesidades y limitaciones del usuario. De esta forma, esta tesis propone un sistema de comunicación aumentativo y alternativo para personas con DCP basado en control fisiológico. Además, se propone un Sistema innovador de control directo sobre tableros de conceptos basado en EMG. Este Sistema de control se basa en un modelo fÃsico que reproduce la respuesta mecánica muscular (basado en parámetros como Rigidez, Inercia y Viscosidad), permitiendo la selección de elementos gracias a pequeños pulsos de señal EMG con sensores sobre un músculo con control motor. Sus principales ventajas son la posibilidad de corregir errores durante la selección asociado a los impulsos musculares no controlados, evitar el esfuerzo muscular mantenido para alcanzar un nivel y reducir la fatiga.La Parà lisi Cerebral de tipus Discinèsica (DCP) es caracteritza principalment per les alteracions del to muscular i els moviments involuntaris. Per açò, aquests pacients presenten dificultats en la coordinació i en el control de moviments, la qual cosa els dificulta el caminar i afecta la seua postura quan estan asseguts. Cal ressaltar que la capacitat cognitiva de les persones amb DCP pot variar des de completament normal, fins a un retard mental sever.
Les persones amb DCP han sigut seleccionades com a objectiu d'aquesta tesi ja el marge de millora de les seues capacitats és ampli grà cies a sistemes de control fisiològic, a causa dels seus múltiples i complexes limitacions (problemes de parla i control motor).
A causa de les seues dificultats de comunicació, algunes persones amb DCP es poden comunicar amb llenguatge escrit, sempre que tinga un bon control motor. No obstant açò, la majoria tenen dificultats per a usar sistemes de Comunicació Augmentatius i Alternatius (AAC). De fet, les persones amb DCP utilitzen generalment taulers de conceptes per a indicar la idea que volen transmetre. No obstant açò, la majoria les solucions de comunicació disponibles en l'actualitat estan basades en programari propietari que fan difÃcil la personalització del tauler de conceptes i el tipus de sistema de control.
És acà on sorgeix aquesta tesi, amb l'objectiu de crear una interfÃcie amb aqueixes caracterÃstiques, capaç d'adaptar-se a les necessitats i limitacions de l'usuari. D'aquesta forma, aquesta tesi proposa un sistema de comunicació augmentatiu i alternatiu per a persones amb DCP basat en control fisiològic. A més, es proposa un sistema innovador de control directe sobre taulers de conceptes basat en EMG. Aquest sistema de control es basa en un model fÃsic que reprodueix la resposta mecà nica muscular (basat en parà metres com a Rigidesa, Inèrcia i Viscositat), permetent la selecció d'elements grà cies a xicotets polsos de senyal EMG amb sensors sobre un múscul amb control motor. Els seus principals avantatges són la possibilitat de corregir errors durant la selecció associat als impulsos musculars no controlats, evitar l'esforç muscular mantingut per a aconseguir un nivell i reduir la fatiga.DÃaz Pineda, JA. (2017). Advanced Augmentative and Alternative Communication System Based in Physiological Control [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/90418TESI
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Revisiting the Potential of EEG Neurofeedback for Patients With Schizophrenia.
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Biological Motion induced mu suppression is reduced in Early Psychosis (EP) patients with active negative symptoms and Autism Spectrum Disorders (ASD).
There is evidence of genetic and neural system overlap in Autism Spectrum Disorder (ASD) and Early Psychosis (EP). Five datasets were pooled to compare mu suppression index (MSI), a proxy of mirror neuron activity, in EP, high functioning ASD, and healthy subjects (HS). ASDs and EPs with "active" negative symptoms showed significant differences in mu suppression, in response to Biological Motion/point-light display animation, compared to HS. Preliminary findings suggest that similar neural network deficits in ASD and EP could be driven by the expression of negative symptoms in the latter group of patients. These findings may aid future studies on EP and ASD and facilitate the formulation of new hypotheses regarding their pathophysiology
Student Training for Motor Performance Assessment in Industry
Energy used by electric motors in the USA According to the US Department of Energy [1], electric motors consume more than 50 percent of all electrical energy in the USA and more than 85 percent of industrial production electrical energy [2]. Furthermore, during the estimated life of an electric motor, approximately 20 years, its initial purchase price is less than 2 percent of the total cost of owning and operating it [3]. 2- The main objective of this work is to share our experience of training university students for performing electric motors energy assessments to local industries with a limited set of instruments: a tachometer, an AC multimeter, and a power meter endowed with two AC probes [4] Instead of acquiring detailed information about the state of the motor, like torque- angular speed characteristics, we aim to determine the electric motor load. Any deviations from the rated motor load would cause the electric motor to spend additional energy[3]. The input power to the motor is measured from parameters taken from hand-held instruments and compared to the power required when the motor operates at rated capacity. In our laboratory, three testing methods [5] have been applied to determine the state of operation of a testing motor loaded with a prony brake. These are: 1- Direct input power measurements with the two-wattmeter configuration 2- Line current measurements 3- The slip method The outcome of this method is the actual motor efficiency. The next step would be to recommend replacing the standard motor with high or premium efficiency motors 3- Integration of the Lab experience into courses These hand-on experiments have been integrated into an undergraduate elective course ELEE 4372 Electric Machines, now taught during the Fall 2021 semester to 15 students. At the end of this course, students will complete a survey rating the class. Additionally, at the end of every test, students will respond to a questionnaire. Questions will be posed to receive students feedback on the contribution of the experiment to their knowledge base, their interest in the subject, and the appropriateness of the tools and workspace under which they worked. 4- In conclusion, we have found that after the students complete these practices, they will be prepared to make assessments of motor performance and write recommendations that will lead to energy savings, for the industries
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