4,595 research outputs found
Correlations, fluctuations and stability of a finite-size network of coupled oscillators
The incoherent state of the Kuramoto model of coupled oscillators exhibits
marginal modes in mean field theory. We demonstrate that corrections due to
finite size effects render these modes stable in the subcritical case, i.e.
when the population is not synchronous. This demonstration is facilitated by
the construction of a non-equilibrium statistical field theoretic formulation
of a generic model of coupled oscillators. This theory is consistent with
previous results. In the all-to-all case, the fluctuations in this theory are
due completely to finite size corrections, which can be calculated in an
expansion in 1/N, where N is the number of oscillators. The N -> infinity limit
of this theory is what is traditionally called mean field theory for the
Kuramoto model.Comment: 25 pages (2 column), 12 figures, modifications for resubmissio
Indonesian Throughflow as a preconditioning mechanism for submarine landslides in the Makassar Strait
This work was completed as part of a Scottish Funding Council (SFC) Global Challenges Research Fund (GCRF) pump-priming project at Heriot Watt University (PI Nicholson). We would like to thank our partners at Bandung Institute of Technology, and the members of the Indonesian Marine Geological Institute and Geological Survey of Indonesia for their discussion and contribution to this research. We thank TGS and Multiclient Geophysical for permission to publish seismic and multibeam data respectively. D.R. Tappin publishes with the permission of the Executive Director of the BGS (United Kingdom Research and Innovation).Peer reviewedPublisher PD
Parasitic Fungi of Illinois. Part I.
Most of the plants herein described were collected in Illinois during 1881 and 1882. by Mr. A. B. Seymour, who was employed for the purpose by the Illinois State Laboratory of Natural History. The entire collection consists of three thousand seven hundred and eighty-four numbers, many of which are of course duplicates, or are different stages of the same species, leaving, however, a very large number of distinct specific forms—much larger than is usually supposed to exist in
our flora.
The determinations have been made at the Illinois Industrial University by myself, efficiently aided by Mr. Seymour. For this work, besides the facilities offered by the library and herbarium of the University, the State Laboratory of Natural History furnished many books and specimens. Among the latter are the following sets of exsiccata: DeThumen's Mycotheca Universalis, Ellis' North American Fungi. Ravenel's Fungi
Caroliniani and Fungi Americani.Ope
Locating the ventral intermediate thalamic nucleus for deep brain stimulation surgery: analysis of a case series comparing CT and MR targeting
\ua9 2024 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.Background: Deep brain stimulation (DBS) surgery targeting the ventral intermediate thalamic nucleus (Vim) has proven efficacy in the treatment of tremor. Aims: The primary aim is to investigate whether there is a statistically significant difference in patient outcomes when CT-guided targeting of the Vim is compared with MRI-guided targeting. Methods: This is a retrospective study concerning patients undergoing Vim-targeted DBS at the Department of Neurosurgery, Royal Victoria Infirmary in Newcastle (9th August 2012 to 4th January 2019). Fahn–Tolosa–Marin Tremor Scale (FTM TS) and EQ-5D scores were collected from patient notes. Statistical analysis was performed using IBM\uae SPSS\uae Statistics Version 24. Independent samples t-tests were used to compare means. Results: Independent samples t-test did not reveal a statistically significant difference between CT (n = 10; FTM TS mean = 65.40, SD = 11.40; EQ-5D mean = 39.50, SD = 17.87) and MR (n = 7; FTM TS mean = 60.57, SD = 7.50; EQ-5D mean = 32.14, SD = 9.94) groups in pre-surgery FTM TS (t(15) = 0.977, p = 0.344) and EQ-5D (t(15) = 0.982, p = 0.342) scores. No statistically significant difference between the CT (FTM TS mean = 24.12, SD = 20.47; EQ-5D mean = 75.56, SD = 15.63) and MR (FTM TS mean = 22.86, SD = 6.72; EQ-5D mean = 70.43, SD = 15.48) groups was revealed at 1 year assessment of FTM TS (t(14) = 0.155, p = 0.879) and EQ-5D (t(14) = 0.654, p = 0.524). The median difference between pre- and post-surgery FTM TS and EQ-5D scores in the CT group at 1 year was 43.00 and 35.00, respectively. The MR patient group median difference in pre- and post-surgery at 1 year was 35.00 and 35.00 respectively. Conclusion: No statistically significant difference between CT and MR image-guided targeting patient groups was detected
L-selectin mediated leukocyte tethering in shear flow is controlled by multiple contacts and cytoskeletal anchorage facilitating fast rebinding events
L-selectin mediated tethers result in leukocyte rolling only above a
threshold in shear. Here we present biophysical modeling based on recently
published data from flow chamber experiments (Dwir et al., J. Cell Biol. 163:
649-659, 2003) which supports the interpretation that L-selectin mediated
tethers below the shear threshold correspond to single L-selectin carbohydrate
bonds dissociating on the time scale of milliseconds, whereas L-selectin
mediated tethers above the shear threshold are stabilized by multiple bonds and
fast rebinding of broken bonds, resulting in tether lifetimes on the timescale
of seconds. Our calculations for cluster dissociation suggest that
the single molecule rebinding rate is of the order of Hz. A similar
estimate results if increased tether dissociation for tail-truncated L-selectin
mutants above the shear threshold is modeled as diffusive escape of single
receptors from the rebinding region due to increased mobility. Using computer
simulations, we show that our model yields first order dissociation kinetics
and exponential dependence of tether dissociation rates on shear stress. Our
results suggest that multiple contacts, cytoskeletal anchorage of L-selectin
and local rebinding of ligand play important roles in L-selectin tether
stabilization and progression of tethers into persistent rolling on endothelial
surfaces.Comment: 9 pages, Revtex, 4 Postscript figures include
Preparation of dissociated mouse primary neuronal cultures from long-term cryopreserved brain tissue
BACKGROUND: Dissociated primary neuronal cultures are widely used as a model system to investigate the cellular and molecular properties of diverse neuronal populations and mechanisms of action potential generation and synaptic transmission. Typically, rodent primary neuronal cultures are obtained from freshly-dissociated embryonic or postnatal brain tissue, which often requires intense animal husbandry. This can strain resources when working with genetically modified mice. NEW METHOD: Here we describe an experimental protocol for frozen storage of mouse hippocampi, which allows fully functional dissociated primary neuronal cultures to be prepared from cryopreserved tissue. RESULTS: We show that thawed hippocampal neurons have functional properties similar to those of freshly dissociated neurons, including neuronal morphology, excitability, action potential waveform and synaptic neurotransmitter release, even after cryopreservation for several years. COMPARISON TO THE EXISTING METHODS: In contrast to the existing methods, the protocol described here allows for efficient long-term storage of samples, allowing researchers to perform functional experiments on neuronal cultures from brain tissue collected in other laboratories. CONCLUSIONS: We anticipate that this method will facilitate collaborations among laboratories based at distant locations and will thus optimise the use of genetically modified mouse models, in line with the 3Rs (Replacement, Reduction and Refinement) recommended for scientific use of animals in research
Achieving Good Angular Resolution in 3D Arc Diagrams
We study a three-dimensional analogue to the well-known graph visualization
approach known as arc diagrams. We provide several algorithms that achieve good
angular resolution for 3D arc diagrams, even for cases when the arcs must
project to a given 2D straight-line drawing of the input graph. Our methods
make use of various graph coloring algorithms, including an algorithm for a new
coloring problem, which we call localized edge coloring.Comment: 12 pages, 5 figures; to appear at the 21st International Symposium on
Graph Drawing (GD 2013
Understanding endocrine resistance: the critical need for sequential samples from clinical breast cancer and novel in vitro models
Coral Disease and Health Workshop: Coral Histopathology II
The health and continued existence of coral reef ecosystems are threatened by an increasing array of environmental and anthropogenic impacts. Coral disease is one of the prominent causes of increased mortality among reefs globally, particularly in the Caribbean. Although over 40 different coral diseases and syndromes have been reported
worldwide, only a few etiological agents have been confirmed; most pathogens remain unknown and the dynamics of disease transmission, pathogenicity and mortality are not
understood. Causal relationships have been documented for only a few of the coral diseases, while new syndromes continue to emerge. Extensive field observations by coral
biologists have provided substantial documentation of a plethora of new pathologies, but our understanding, however, has been limited to descriptions of gross lesions with names reflecting these observations (e.g., black band, white band, dark spot). To determine etiology, we must equip coral diseases scientists with basic biomedical knowledge and specialized training in areas such as histology, cell biology and pathology. Only through
combining descriptive science with mechanistic science and employing the synthesis epizootiology provides will we be able to gain insight into causation and become equipped to handle the pending crisis.
One of the critical challenges faced by coral disease researchers is to establish a framework to systematically study coral pathologies drawing from the field of diagnostic
medicine and pathology and using generally accepted nomenclature. This process began in April 2004, with a workshop titled Coral Disease and Health Workshop: Developing Diagnostic Criteria co-convened by the Coral Disease and Health Consortium (CDHC), a working group organized under the auspices of the U.S. Coral Reef Task Force, and the International Registry for Coral Pathology (IRCP). The workshop was hosted by the U.S. Geological Survey, National Wildlife Health Center (NWHC) in Madison, Wisconsin and was focused on gross morphology and disease signs observed in the field. A resounding recommendation from the histopathologists participating in the workshop was the urgent need to develop diagnostic criteria that are suitable to move from gross observations to morphological diagnoses based on evaluation of microscopic anatomy. (PDF contains 92 pages
Models of the SL9 Impacts II. Radiative-hydrodynamic Modeling of the Plume Splashback
We model the plume "splashback" phase of the SL9 collisions with Jupiter
using the ZEUS-3D hydrodynamic code. We modified the Zeus code to include gray
radiative transport, and we present validation tests. We couple the infalling
mass and momentum fluxes of SL9 plume material (from paper I) to a jovian
atmospheric model. A strong and complex shock structure results. The modeled
shock temperatures agree well with observations, and the structure and
evolution of the modeled shocks account for the appearance of high excitation
molecular line emission after the peak of the continuum light curve. The
splashback region cools by radial expansion as well as by radiation. The
morphology of our synthetic continuum light curves agree with observations over
a broad wavelength range (0.9 to 12 microns). A feature of our ballistic plume
is a shell of mass at the highest velocities, which we term the "vanguard".
Portions of the vanguard ejected on shallow trajectories produce a lateral
shock front, whose initial expansion accounts for the "third precursors" seen
in the 2-micron light curves of the larger impacts, and for hot methane
emission at early times. Continued propagation of this lateral shock
approximately reproduces the radii, propagation speed, and centroid positions
of the large rings observed at 3-4 microns by McGregor et al. The portion of
the vanguard ejected closer to the vertical falls back with high z-component
velocities just after maximum light, producing CO emission and the "flare" seen
at 0.9 microns. The model also produces secondary maxima ("bounces") whose
amplitudes and periods are in agreement with observations.Comment: 13 pages, 9 figures (figs 3 and 4 in color), accepted for Ap.J.
latex, version including full figures at:
http://oobleck.tn.cornell.edu/jh/ast/papers/slplume2-20.ps.g
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