1,375 research outputs found
A reexamination of end-point and rebound nystagmus in normals.
In order to detail the characteristics of end-point (EPN) and rebound nystagmus (RN), two series of
experiments were performed with infrared oculography for measurement of horizontal eye movements.
Experiment 1 consisted of EPN recordings during sustained lateral gaze (40° and 50°) in 20 normal
subjects. Experiment 2 consisted of recordings of RN in 5 normal subjects. Nine of 20 subjects
demonstrated a jerk EPN. EPN almost always appeared immediately and was sustained for 15-25 sec.
In Experiment 2, RN occurred in 5 of the 5 subjects who demonstrated EPN. The mean amplitude of
RN was always less than that of EPN, and decayed over a 5-10-sec time period. The experiment
demonstrated that RN can be evoked in normals even when a fixation target, in a fully lit room, is
present
Charakterisierung des elektrochemischen Mikroanalysesystems ELMAS
Am Forschungszentrum Karlsruhe wurde im Rahmen des Projekts Mikrosystemtechnik das modular aufgebaute elektrochemische Mikroanalysesystem ELMAS unter Verwendung von ISFET-Mikrosensoren und gasfördernden Mikromembranpumpen entwickelt. Der Lösungstransport erfolgt indirekt ĂŒber die DruckĂ€nderungen im Luft- volumen, das sich ĂŒber der Lösung im VorratsbehĂ€lter befindet. Die pH-ISFETs zeigen ein schnelles Ansprechverhalten und mit FluĂraten von 200-300 ”l/min sind Zykluszeiten fĂŒr die Messung und Sensorkalibrierung von 30-60 s realisierbar. Bei Erhöhung der FluĂraten sinkt die Zykluszeit, der Lösungsverbrauch hingegen nimmt zu. FĂŒr eine Messung sind ca. 50 ”l Analyt und maximal 70 ”l Kalibrierlösung erforderlich. Aufgrund des Gaspuffers im VorratsgefÀà ist der Fluidstrom gegenĂŒber den Schaltsignalen der Pumpen um 5 s verzögert
A closer look at the uncertainty relation of position and momentum
We consider particles prepared by the von Neumann-L\"uders projection. For
those particles the standard deviation of the momentum is discussed. We show
that infinite standard deviations are not exceptions but rather typical. A
necessary and sufficient condition for finite standard deviations is given.
Finally, a new uncertainty relation is derived and it is shown that the latter
cannot be improved.Comment: 3 pages, introduction shortened, content unchange
Short-range repulsion and isospin dependence in the KN system
The short-range properties of the KN interaction are studied within the
meson-exchange model of the Juelich group. Specifically, dynamical explanations
for the phenomenological short-range repulsion, required in this model for
achieving agreement with the empirical KN data, are explored. Evidence is found
that contributions from the exchange of a heavy scalar-isovector meson
(a_0(980)) as well as from genuine quark-gluon exchange processes are needed.
Taking both mechanisms into account a satisfactory description of the KN phase
shifts can be obtained without resorting to phenomenological pieces.Comment: 26 pages, 5 figure
Partial clustering prevents global crystallization in a binary 2D colloidal glass former
A mixture of two types of super-paramagnetic colloidal particles with long
range dipolar interaction is confined by gravity to a flat interface of a
hanging water droplet. The particles are observed by video microscopy and the
dipolar interaction strength is controlled via an external magnetic field. The
system is a model system to study the glass transition in 2D, and it exhibits
partial clustering of the small particles. This clustering is strongly
dependent on the relative concentration of big and small particles.
However, changing the interaction strength reveals that the clustering
does not depend on the interaction strength. The partial clustering scenario is
quantified using Minkowski functionals and partial structure factors. Evidence
that partial clustering prevents global crystallization is discussed
DAC-h3: A Proactive Robot Cognitive Architecture to Acquire and Express Knowledge About the World and the Self
This paper introduces a cognitive architecture for a humanoid robot to engage in a proactive, mixed-initiative exploration and manipulation of its environment, where the initiative can originate from both the human and the robot. The framework, based on a biologically-grounded theory of the brain and mind, integrates a reactive interaction engine, a number of state-of-the art perceptual and motor learning algorithms, as well as planning abilities and an autobiographical memory. The architecture as a whole drives the robot behavior to solve the symbol grounding problem, acquire language capabilities, execute goal-oriented behavior, and express a verbal narrative of its own experience in the world. We validate our approach in human-robot interaction experiments with the iCub humanoid robot, showing that the proposed cognitive architecture can be applied in real time within a realistic scenario and that it can be used with naive users
Regularity issues in the problem of fluid structure interaction
We investigate the evolution of rigid bodies in a viscous incompressible
fluid. The flow is governed by the 2D Navier-Stokes equations, set in a bounded
domain with Dirichlet boundary conditions. The boundaries of the solids and the
domain have H\"older regularity , . First, we
show the existence and uniqueness of strong solutions up to collision. A key
ingredient is a BMO bound on the velocity gradient, which substitutes to the
standard estimate for smoother domains. Then, we study the asymptotic
behaviour of one body falling over a flat surface. We show that
collision is possible in finite time if and only if
Brain structure and neurocognitive function in two professional mountaineers during 35âdays of severe normobaric hypoxia
Background and purpose
Animal studies suggest that exposure to severe ambient hypoxia for several days may have beneficial long-term effects on neurodegenerative diseases. Because, the acute risks of exposing human beings to prolonged severe hypoxia on brain structure and function are uncertain, we conducted a pilot study in healthy persons.
Methods
We included two professional mountaineers (participants A and B) in a 35-day study comprising an acclimatization period and 14 consecutive days with oxygen concentrations between 8% and 8.8%. They underwent cerebral magnetic resonance imaging at seven time points and a cognitive test battery covering a spectrum of cognitive domains at 27 time points. We analysed blood neuron specific enolase and neurofilament light chain levels before, during, and after hypoxia.
Results
In hypoxia, white matter volumes increased (maximum: A, 4.3%â±â0.9%; B, 4.5%â±â1.9%) whilst gray matter volumes (A, â1.5%â±â0.8%; B, â2.5%â±â0.9%) and cerebrospinal fluid volumes (A, â2.7%â±â2.4%; B, â5.9%â±â8.2%) decreased. Furthermore, the number (A, 11â17; B, 26â126) and volumes (A, 140%; B, 285%) of white matter hyperintensities increased in hypoxia but had returned to baseline after a 3.5-month recovery phase. Diffusion weighted imaging of the white matter indicated cytotoxic edema formation. We did not observe changes in cognitive performance or biochemical brain injury markers.
Discussion
In highly selected healthy individuals, severe sustained normobaric hypoxia over 2âweeks elicited reversible changes in brain morphology without clinically relevant changes in cognitive function or brain injury markers. The finding may pave the way for future translational studies assessing the therapeutic potential of hypoxia in neurodegenerative diseases
Genomic cloning and linkage mapping of the Mal d 1 (PR-10) gene family in apple (Malus domestica)
Fresh apples can cause birch pollen-related food allergy in northern and central European populations, primarily because of the presence of Mal d 1, the major apple allergen that is cross-reactive to the homologous and sensitizing allergen Bet v 1 from birch. Apple cultivars differ significantly in their allergenicity. Knowledge of the genetic basis of these differences would direct breeding for hypoallergenic cultivars. The PCR genomic cloning and sequencing were performed on two cultivars, Prima and Fiesta, which resulted in 37 different Mal d 1 gDNA sequences. Based on the mapping of sequence-specific molecular markers, these sequences appeared to represent 18 Mal d 1 genes. Sixteen genes were located in two clusters, one cluster with seven genes on linkage group (LG) 13, and the other cluster with nine genes on the homoeologous LG 16. One gene was mapped on LG 6, and one remained unmapped. According to sequence identity, these 18 genes could be subdivided into four subfamilies. Subfamilies IâIII had an intron of different size that was subfamily and gene-specific. Subfamily IV consisted of 11 intronless genes. The deduced amino acid sequence identity varied from 65% to 81% among subfamilies, from 82% to 100% among genes within a subfamily, and from 97.5% to 100% among alleles of one gene. This study provides a better understanding of the genetics of Mal d 1 and the basis for further research on the occurrence of allelic diversity among cultivars in relation to allergenicity and their biological functions
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