7,289 research outputs found
The human as a detector of changes in variance and bandwidth
The detection of changes in random process variance and bandwidth was studied. Psychophysical thresholds for these two parameters were determined using an adaptive staircase technique for second order random processes at two nominal periods (1 and 3 seconds) and damping ratios (0.2 and 0.707). Thresholds for bandwidth changes were approximately 9% of nominal except for the (3sec,0.2) process which yielded thresholds of 12%. Variance thresholds averaged 17% of nominal except for the (3sec,0.2) process in which they were 32%. Detection times for suprathreshold changes in the parameters may be roughly described by the changes in RMS velocity of the process. A more complex model is presented which consists of a Kalman filter designed for the nominal process using velocity as the input, and a modified Wald sequential test for changes in the variance of the residual. The model predictions agree moderately well with the experimental data. Models using heuristics, e.g. level crossing counters, were also examined and are found to be descriptive but do not afford the unification of the Kalman filter/sequential test model used for changes in mean
Pancreatic secretory trypsin inhibitor stimulates the growth of rat pancreatic carcinoma cells
Considerations for the design of an onboard air traffic situation display
The basic concept of remoting information to the cockpit is used to design and develop a computerized airborne traffic situation display device that automatically selects and presents segments of a controller's scope to the aircraft pilot via a narrow band digital data link. These data are integrated with aircraft heading and navigation information to provide a display useful in congested air space. The display can include alphanumerical symbols, air route maps, and controller instructions
Revealing Relationships among Relevant Climate Variables with Information Theory
A primary objective of the NASA Earth-Sun Exploration Technology Office is to
understand the observed Earth climate variability, thus enabling the
determination and prediction of the climate's response to both natural and
human-induced forcing. We are currently developing a suite of computational
tools that will allow researchers to calculate, from data, a variety of
information-theoretic quantities such as mutual information, which can be used
to identify relationships among climate variables, and transfer entropy, which
indicates the possibility of causal interactions. Our tools estimate these
quantities along with their associated error bars, the latter of which is
critical for describing the degree of uncertainty in the estimates. This work
is based upon optimal binning techniques that we have developed for
piecewise-constant, histogram-style models of the underlying density functions.
Two useful side benefits have already been discovered. The first allows a
researcher to determine whether there exist sufficient data to estimate the
underlying probability density. The second permits one to determine an
acceptable degree of round-off when compressing data for efficient transfer and
storage. We also demonstrate how mutual information and transfer entropy can be
applied so as to allow researchers not only to identify relations among climate
variables, but also to characterize and quantify their possible causal
interactions.Comment: 14 pages, 5 figures, Proceedings of the Earth-Sun System Technology
Conference (ESTC 2005), Adelphi, M
Remote Care plc. Developing the capacity of the remote care industry to supply Britain’s future needs.
Three-dimensional MHD Simulations of Jets from Accretion Disks
We report the results of 3-dimensional magnetohydrodynamic (MHD) simulations
of a jet formation by the interaction between an accretion disk and a large
scale magnetic field. The disk is not treated as a boundary condition but is
solved self-consistently. To investigate the stability of MHD jet, the
accretion disk is perturbed with a non-axisymmetric sinusoidal or random
fluctuation of the rotational velocity. The dependences of the jet velocity
, mass outflow rate , and mass accretion rate
on the initial magnetic field strength in both non-axisymmetric cases are
similar to those in the axisymmetric case. That is, ,
and where is the
initial magnetic field strength. The former two relations are consistent with
the Michel's steady solution, , although
the jet and accretion do not reach the steady state. In both perturbation
cases, a non-axisymmetric structure with appears in the jet, where
means the azimuthal wave number. This structure can not be explained by
Kelvin-Helmholtz instability and seems to originate in the accretion disk.
Non-axisymmetric modes in the jet reach almost constant levels after about 1.5
orbital periods of the accretion disk, while all modes in the accretion disk
grow with oscillation. As for the angular momentum transport by Maxwell stress,
the vertical component, , in the wide range of initial magnetic field
strength.Comment: Accepted for publication in ApJ. The pdf file with high resolution
figures can be downloaded at
http://www.kusastro.kyoto-u.ac.jp/~hiromitu/3j050806.pd
Growing grassroots innovations: exploring the role of community-based initiatives in governing sustainable energy transitions
The clinical anatomy of the cephalic vein in the deltopectoral triangle
Identification and recognition of the cephalic vein in the deltopectoral triangle
is of critical importance when considering emergency catheterization procedures.
The aim of our study was to conduct a cadaveric study to access data
regarding the topography and the distribution patterns of the cephalic vein as
it relates to the deltopectoral triangle. One hundred formalin fixed cadavers
were examined. The cephalic vein was found in 95% (190 right and left) specimens,
while in the remaining 5% (10) the cephalic vein was absent. In 80%
(152) of cases the cephalic vein was found emerging superficially in the lateral
portion of the deltopectoral triangle. In 30% (52) of these 152 cases the cephalic
vein received one tributary within the deltopectoral triangle, while in 70%
(100) of the specimens it received two. In the remaining 20% (38) of cases the
cephalic vein was located deep to the deltopectoral fascia and fat and did not
emerge through the deltopectoral triangle but was identified medially to the
coracobrachialis and inferior to the medial border of the deltoid. In addition,
in 4 (0.2%) of the specimens the cephalic vein, after crossing the deltopectoral
triangle, ascended anterior and superior to the clavicle to drain into the subclavian
vein. In these specimens a collateral branch was observed to communicate
between the cephalic and external jugular veins. In 65.2% (124) of the cases
the cephalic vein traveled with the deltoid branch of the thoracoacromial trunk.
The length of the cephalic vein within the deltopectoral triangle ranged from
3.5 cm to 8.2 cm with a mean of 4.8 ± 0.7 cm. The morphometric analysis
revealed a mean cephalic vein diameter of 0.8 ± 0.1 cm with a range of 0.1 cm
to 1.2 cm. The cephalic vein is relatively large and constant, usually allowing
for easy cannulation. (Folia Morphol 2008; 67: 72-77
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