1,131 research outputs found
Formation of roll waves in laminar street flow
CER84-85PYJ-DMH18.Includes bibliographical references (pages 24-25).January 1985
A cell-permeable biscyclooctyne as a novel probe for the identification of protein sulfenic acids
Reactive oxygen species act as important second messengers in cell signaling and homeostasis through the oxidation of protein thiols. However, the dynamic nature of protein oxidation and the lack of sensitivity of existing molecular probes have hindered our understanding of such reactions; therefore, new tools are required to address these challenges. We designed a bifunctional variant of the strained bicyclo[6.1.0]nonyne (BCN-E-BCN) that enables the tagging of intracellular protein sulfenic acids for biorthogonal copper-free click chemistry. In validation studies, BCN-E-BCN binds the sulfenylated form of the actin-severing protein cofilin, while mutation of the cognate cysteine residues abrogates its binding. BCN-E-BCN is cell permeable and reacts rapidly with cysteine sulfenic acids in cultured cells. Using different azide-tagged conjugates, we demonstrate that BCN-E-BCN can be used in various applications for the detection of sulfenylated proteins. Remarkably, cycloaddition of an azide-tagged fluorophore to BCN-E-BCN labelled proteins produced in vivo can be visualized by fluorescence microscopy to reveal their subcellular localization. These findings demonstrate a novel and multifaceted approach to the detection and trapping of sulfenic acids
On Waylen's regular axisymmetric similarity solutions
We review the similarity solutions proposed by Waylen for a regular
time-dependent axisymmetric vacuum space-time, and show that the key equation
introduced to solve the invariant surface conditions is related by a Baecklund
transform to a restriction on the similarity variables. We further show that
the vacuum space-times produced via this path automatically possess a (possibly
homothetic) Killing vector, which may be time-like.Comment: 8 pages, LaTeX2
Self-Calibration of Cameras with Euclidean Image Plane in Case of Two Views and Known Relative Rotation Angle
The internal calibration of a pinhole camera is given by five parameters that
are combined into an upper-triangular calibration matrix. If the
skew parameter is zero and the aspect ratio is equal to one, then the camera is
said to have Euclidean image plane. In this paper, we propose a non-iterative
self-calibration algorithm for a camera with Euclidean image plane in case the
remaining three internal parameters --- the focal length and the principal
point coordinates --- are fixed but unknown. The algorithm requires a set of point correspondences in two views and also the measured relative
rotation angle between the views. We show that the problem generically has six
solutions (including complex ones).
The algorithm has been implemented and tested both on synthetic data and on
publicly available real dataset. The experiments demonstrate that the method is
correct, numerically stable and robust.Comment: 13 pages, 7 eps-figure
Hyperinfectivity: A Critical Element in the Ability of V. cholerae to Cause Epidemics?
BACKGROUND: Cholera is an ancient disease that continues to cause epidemic and pandemic disease despite ongoing efforts to limit its spread. Mathematical models provide one means of assessing the utility of various proposed interventions. However, cholera models that have been developed to date have had limitations, suggesting that there are basic elements of cholera transmission that we still do not understand. METHODS AND FINDINGS: Recent laboratory findings suggest that passage of Vibrio cholerae O1 Inaba El Tor through the gastrointestinal tract results in a short-lived, hyperinfectious state of the organism that decays in a matter of hours into a state of lower infectiousness. Incorporation of this hyperinfectious state into our disease model provides a much better fit with the observed epidemic pattern of cholera. These findings help to substantiate the clinical relevance of laboratory observations regarding the hyperinfectious state, and underscore the critical importance of human-to-human versus environment-to-human transmission in the generation of epidemic and pandemic disease. CONCLUSIONS: To have maximal impact on limiting epidemic spread of cholera, interventions should be targeted toward minimizing risk of transmission of the short-lived, hyperinfectious form of toxigenic Vibrio cholerae. The possibility of comparable hyperinfectious states in other major epidemic diseases also needs to be evaluated and, as appropriate, incorporated into models of disease prevention
CN Morphology Studies of Comet 103P/Hartley 2
We report on narrowband CN imaging of Comet 103P/Hartley 2 obtained at Lowell
Observatory on 39 nights from 2010 July until 2011 January. We observed two
features, one generally to the north and the other generally to the south. The
CN morphology varied during the apparition: no morphology was seen in July; in
August and September the northern feature dominated and appeared as a mostly
face-on spiral; in October, November, and December the northern and southern
features were roughly equal in brightness and looked like more side-on
corkscrews; in January the southern feature was dominant but the morphology was
indistinct due to very low signal. The morphology changed smoothly during each
night and similar morphology was seen from night to night. However, the
morphology did not exactly repeat each rotation cycle, suggesting that there is
a small non-principal axis rotation. Based on the repetition of the morphology,
we find evidence that the fundamental rotation period was increasing: 16.7 hr
from August 13-17, 17.2 hr from September 10-13, 18.2 hr from October 12-19,
and 18.7 hr from October 31-November 7. We conducted Monte Carlo jet modeling
to constrain the pole orientation and locations of the active regions based on
the observed morphology. Our preliminary, self-consistent pole solution has an
obliquity of 10 deg relative to the comet's orbital plane (i.e., it is centered
near RA = 257 deg and Dec=+67 deg with an uncertainty around this position of
about 15 deg) and has two mid-latitude sources, one in each hemisphere.Comment: Accepted by The Astronomical Journal; 23 pages of text, 2 tables, 8
figure
Mental Health Services in Rural Jails [Policy Brief]
Based on interviews with state and local corrections and mental health informants in four rural states (Minnesota, Montana, Texas, and Vermont), the researchers sought to learn more about hte challenges that rural jails face along with promising practices being used to meet the needs of inmates with mental health concerns
Effects of Temperature on Emergence and Seasonality of West Nile Virus in California
Temperature has played a critical role in the spatiotemporal dynamics of West Nile virus transmission throughout California from its introduction in 2003 through establishment by 2009. We compared two novel mechanistic measures of transmission risk, the temperature-dependent ratio of virus extrinsic incubation period to the mosquito gonotrophic period (BT), and the fundamental reproductive ratio (R0) based on a mathematical model, to analyze spatiotemporal patterns of receptivity to viral amplification. Maps of BT and R0 were created at 20-km scale and compared throughout California to seroconversions in sentinel chicken flocks at half-month intervals. Overall, estimates of BT and R0 agreed with intensity of transmission measured by the frequency of sentinel chicken seroconversions. Mechanistic measures such as these are important for understanding how temperature affects the spatiotemporal dynamics of West Nile virus transmission and for delineating risk estimates useful to inform vector control agency intervention decisions and communicate outbreak potential
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