2,192 research outputs found
Alternative Fourier Expansions for Inverse Square Law Forces
Few-body problems involving Coulomb or gravitational interactions between
pairs of particles, whether in classical or quantum physics, are generally
handled through a standard multipole expansion of the two-body potentials. We
discuss an alternative based on a compact, cylindrical Green's function
expansion that should have wide applicability throughout physics. Two-electron
"direct" and "exchange" integrals in many-electron quantum systems are
evaluated to illustrate the procedure which is more compact than the standard
one using Wigner coefficients and Slater integrals.Comment: 10 pages, latex/Revtex4, 1 figure
Cardiac rhythm device identification using neural networks
Background Medical staff often need to determine the model of a pacemaker or defibrillator (cardiac rhythm devices) quickly and accurately. Current approaches involve comparing a device’s X-ray appearance with a manual flow chart. We aimed to see whether a neural network could be trained to perform this task more accurately. Methods and Results We extracted X-ray images of 1676 devices, comprising 45 models from 5 manufacturers. We developed a convolutional neural network to classify the images, using a training set of 1451 images. The testing set was a further 225 images, consisting of 5 examples of each model. We compared the network’s ability to identify the manufacturer of a device with those of cardiologists using a published flow-chart. The neural network was 99.6% (95% CI 97.5 to 100) accurate in identifying the manufacturer of a device from an X-ray, and 96.4% (95% CI 93.1 to 98.5) accurate in identifying the model group. Amongst 5 cardiologists using the flow-chart, median manufacturer accuracy was 72.0% (range 62.2% to 88.9%), and model group identification was not possible. The network was significantly superior to all of the cardiologists in identifying the manufacturer (p < 0.0001 against the median human; p < 0.0001 against the best human). Conclusions A neural network can accurately identify the manufacturer and even model group of a cardiac rhythm device from an X-ray, and exceeds human performance. This system may speed up the diagnosis and treatment of patients with cardiac rhythm devices and it is publicly accessible online
Loss of the ciliary protein Chibby1 in mice leads to exocrine pancreatic degeneration and pancreatitis
Primary cilia protrude from the apical surface of many cell types and act as a sensory organelle that regulates diverse biological processes ranging from chemo- and mechanosensation to signaling. Ciliary dysfunction is associated with a wide array of genetic disorders, known as ciliopathies. Polycystic lesions are commonly found in the kidney, liver, and pancreas of ciliopathy patients and mouse models. However, the pathogenesis of the pancreatic phenotype remains poorly understood. Chibby1 (Cby1), a small conserved coiled-coil protein, localizes to the ciliary base and plays a crucial role in ciliogenesis. Here, we report that Cby1-knockout (KO) mice develop severe exocrine pancreatic atrophy with dilated ducts during early postnatal development. A significant reduction in the number and length of cilia was observed in Cby1-KO pancreta. In the adult Cby1-KO pancreas, inflammatory cell infiltration and fibrosis were noticeable. Intriguingly, Cby1-KO acinar cells showed an accumulation of zymogen granules (ZGs) with altered polarity. Moreover, isolated acini from Cby1-KO pancreas exhibited defective ZG secretion in vitro. Collectively, our results suggest that, upon loss of Cby1, concomitant with ciliary defects, acinar cells accumulate ZGs due to defective exocytosis, leading to cell death and progressive exocrine pancreatic degeneration after birth
The kinematics of coronal mass ejections using multiscale methods
The diffuse morphology and transient nature of coronal mass ejections (CMEs)
make them difficult to identify and track using traditional image processing
techniques. We apply multiscale methods to enhance the visibility of the faint
CME front. This enables an ellipse characterisation to objectively study the
changing morphology and kinematics of a sample of events imaged by the Large
Angle Spectrometric Coronagraph (LASCO) onboard the Solar and Heliospheric
Observatory (SOHO) and the Sun Earth Connection Coronal and Heliospheric
Investigation (SECCHI) onboard the Solar Terrestrial Relations Observatory
(STEREO). The accuracy of these methods allows us to test the CMEs for
non-constant acceleration and expansion.
We exploit the multiscale nature of CMEs to extract structure with a
multiscale decomposition, akin to a Canny edge detector. Spatio-temporal
filtering highlights the CME front as it propagates in time. We apply an
ellipse parameterisation of the front to extract the kinematics (height,
velocity, acceleration) and changing morphology (width, orientation).
The kinematic evolution of the CMEs discussed in this paper have been shown
to differ from existing catalogues. These catalogues are based upon
running-difference techniques that can lead to over-estimating CME heights. Our
resulting kinematic curves are not well-fitted with the constant acceleration
model. It is shown that some events have high acceleration below 5
R_{\sun}. Furthermore, we find that the CME angular widths measured by these
catalogues are over-estimated, and indeed for some events our analysis shows
non-constant CME expansion across the plane-of-sky.Comment: 10 pages, 13 figures, accepted for publicatio
The Vehicle, Fall 1994
Table of Contents
Poetry
Noah\u27s WifeJennifer Moropage 8-9
The Intensity of a BreathHeather Anne Winterspage 10-11
When I Was RainNicole Moonpage 11
Wreckage at Low Tide, After a Storm On Cape FearMatt Parkspage 12-14
two belowKeith Spearpage 16
HeatScott Langrenpage 17
Plastic Shard WordsMatthew J. Nelsonpage 18
Mr. Snowplow ManMartin Paul Brittpage 19
Carpe DiemMichael Lairpage 19
untitledWalt Howardpage 20
The GameKellie J. Olsenpage 21
AT PEACEJennifer Surmanpage 22
SawdustSue Songerpage 23
Photography
Unbound RealitiesKris Quiriconipage 26
untitled Mark Porter page 27
untitled Mark Porter page 28
untitled Mark Porter page 29
Prose
I am Here...RememberingJ. Dylan McNeillpage 32-34
RecognitionSue Songerpage 35-36
SACCADICSteve Beinpage 37-40
The BurnBryan Levekpage 41-45
Biographiespage 46-48https://thekeep.eiu.edu/vehicle/1063/thumbnail.jp
The Vehicle, Fall 1994
Table of Contents
Poetry
Noah\u27s WifeJennifer Moropage 8-9
The Intensity of a BreathHeather Anne Winterspage 10-11
When I Was RainNicole Moonpage 11
Wreckage at Low Tide, After a Storm On Cape FearMatt Parkspage 12-14
two belowKeith Spearpage 16
HeatScott Langrenpage 17
Plastic Shard WordsMatthew J. Nelsonpage 18
Mr. Snowplow ManMartin Paul Brittpage 19
Carpe DiemMichael Lairpage 19
untitledWalt Howardpage 20
The GameKellie J. Olsenpage 21
AT PEACEJennifer Surmanpage 22
SawdustSue Songerpage 23
Photography
Unbound RealitiesKris Quiriconipage 26
untitled Mark Porter page 27
untitled Mark Porter page 28
untitled Mark Porter page 29
Prose
I am Here...RememberingJ. Dylan McNeillpage 32-34
RecognitionSue Songerpage 35-36
SACCADICSteve Beinpage 37-40
The BurnBryan Levekpage 41-45
Biographiespage 46-48https://thekeep.eiu.edu/vehicle/1063/thumbnail.jp
Non-monotonic variation with salt concentration of the second virial coefficient in protein solutions
The osmotic virial coefficient of globular protein solutions is
calculated as a function of added salt concentration at fixed pH by computer
simulations of the ``primitive model''. The salt and counter-ions as well as a
discrete charge pattern on the protein surface are explicitly incorporated. For
parameters roughly corresponding to lysozyme, we find that first
decreases with added salt concentration up to a threshold concentration, then
increases to a maximum, and then decreases again upon further raising the ionic
strength. Our studies demonstrate that the existence of a discrete charge
pattern on the protein surface profoundly influences the effective interactions
and that non-linear Poisson Boltzmann and Derjaguin-Landau-Verwey-Overbeek
(DLVO) theory fail for large ionic strength. The observed non-monotonicity of
is compared to experiments. Implications for protein crystallization are
discussed.Comment: 43 pages, including 17 figure
Long-Baseline Neutrino Facility (LBNF) and Deep Underground Neutrino Experiment (DUNE) Conceptual Design Report Volume 2: The Physics Program for DUNE at LBNF
The Physics Program for the Deep Underground Neutrino Experiment (DUNE) at
the Fermilab Long-Baseline Neutrino Facility (LBNF) is described
National culture and tourist destination choice in the UK and Venezuela: an exploratory and preliminary study
National culture determines consumer attitudes and behaviour. While this holds true for tourism
consumption, little research has sought to better understand the effect of culture on tourist
destination choice. The geographical scope of analysis has also been restricted. This study
employs the Hofstede’s cultural dimensions framework to conduct an exploratory, qualitative
evaluation of the influence of the tourist cultural background on destination choice. It focuses on
the UK and Venezuela, the two countries with significant cultural differences and forecast
growth in outbound tourism. The study shows the distinct role of culture in tourist preferences
for destination choice and structure of travel groups. The effect of culture is also recorded in how
tourists research destinations prior to visit and perceive travel risks, thus ultimately influencing
their motivation to travel. Recommendations are developed on how to integrate knowledge on
the cultural background of tourists into tourism management and policy-making practices
Kernel Flow:a high channel count scalable time-domain functional near-infrared spectroscopy system
Significance: Time-domain functional near-infrared spectroscopy (TD-fNIRS) has been considered as the gold standard of noninvasive optical brain imaging devices. However, due to the high cost, complexity, and large form factor, it has not been as widely adopted as continuous wave NIRS systems. Aim: Kernel Flow is a TD-fNIRS system that has been designed to break through these limitations by maintaining the performance of a research grade TD-fNIRS system while integrating all of the components into a small modular device. Approach: The Kernel Flow modules are built around miniaturized laser drivers, custom integrated circuits, and specialized detectors. The modules can be assembled into a system with dense channel coverage over the entire head. Results: We show performance similar to benchtop systems with our miniaturized device as characterized by standardized tissue and optical phantom protocols for TD-fNIRS and human neuroscience results. Conclusions: The miniaturized design of the Kernel Flow system allows for broader applications of TD-fNIRS.</p
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