1,105 research outputs found
Fast measurement of SEP for monitoring spinal cord during scoliosis
Recently there has been considerable interest in the use of somatosensory evoked potential (SEP) for monitoring the functional integrity of the spinal cord during surgery such as scoliosis. This paper describes a monitoring system and signal processing algorithms, which consist of an artificial neural network filter and a wavelet signal enhancer developed to enhance the signal-to-noise ratio (SNR) of surface recorded SEP. Our system allows fast detection of change in SEP's peak latency, amplitude and signal waveform, which are the main parameters of interest during intra-operative procedures.published_or_final_versionThe 20th IEEE Engineering in Medicine and Biology Society Conference Proceedings, Hong Kong, China, 29 October - 1 November 1998, v. 4, p. 2239-224
Prediction of prostate cancer Gleason score upgrading from biopsy to radical prostatectomy using pre-biopsy multiparametric MRI PIRADS scoring system
Soliton pair creation in classical wave scattering
We study classical production of soliton-antisoliton pairs from colliding
wave packets in (1+1)-dimensional scalar field model. Wave packets represent
multiparticle states in quantum theory; we characterize them by energy E and
particle number N. Sampling stochastically over the forms of wave packets, we
find the entire region in (E,N) plane which corresponds to classical creation
of soliton pairs. Particle number is parametrically large within this region
meaning that the probability of soliton-antisoliton pair production in
few-particle collisions is exponentially suppressed.Comment: 16 pages, 8 figures, journal version; misprint correcte
Massive stars as thermonuclear reactors and their explosions following core collapse
Nuclear reactions transform atomic nuclei inside stars. This is the process
of stellar nucleosynthesis. The basic concepts of determining nuclear reaction
rates inside stars are reviewed. How stars manage to burn their fuel so slowly
most of the time are also considered. Stellar thermonuclear reactions involving
protons in hydrostatic burning are discussed first. Then I discuss triple alpha
reactions in the helium burning stage. Carbon and oxygen survive in red giant
stars because of the nuclear structure of oxygen and neon. Further nuclear
burning of carbon, neon, oxygen and silicon in quiescent conditions are
discussed next. In the subsequent core-collapse phase, neutronization due to
electron capture from the top of the Fermi sea in a degenerate core takes
place. The expected signal of neutrinos from a nearby supernova is calculated.
The supernova often explodes inside a dense circumstellar medium, which is
established due to the progenitor star losing its outermost envelope in a
stellar wind or mass transfer in a binary system. The nature of the
circumstellar medium and the ejecta of the supernova and their dynamics are
revealed by observations in the optical, IR, radio, and X-ray bands, and I
discuss some of these observations and their interpretations.Comment: To be published in " Principles and Perspectives in Cosmochemistry"
Lecture Notes on Kodai School on Synthesis of Elements in Stars; ed. by Aruna
Goswami & Eswar Reddy, Springer Verlag, 2009. Contains 21 figure
Potential Landscape and Probabilistic Flux of a Predator Prey Network
Predator-prey system, as an essential element of ecological dynamics, has been recently studied experimentally with synthetic biology. We developed a global probabilistic landscape and flux framework to explore a synthetic predator-prey network constructed with two Escherichia coli populations. We developed a self consistent mean field method to solve multidimensional problem and uncovered the potential landscape with Mexican hat ring valley shape for predator-prey oscillations. The landscape attracts the system down to the closed oscillation ring. The probability flux drives the coherent oscillations on the ring. Both the landscape and flux are essential for the stable and coherent oscillations. The landscape topography characterized by the barrier height from the top of Mexican hat to the closed ring valley provides a quantitative measure of global stability of system. The entropy production rate for the energy dissipation is less for smaller environmental fluctuations or perturbations. The global sensitivity analysis based on the landscape topography gives specific predictions for the effects of parameters on the stability and function of the system. This may provide some clues for the global stability, robustness, function and synthetic network design
The influence of initial xylose concentration, agitation, and aeration on ethanol production by Pichia stipitis from rice straw hemicellulosic hydrolysate
Rice straw hemicellulosic hydrolysate was used as fermentation medium for ethanol production by Pichia stipitis NRRL Y-7124. Shaking bath experiments were initially performed aiming to establish the best initial xylose concentration to be used in this bioconversion process. In the sequence, assays were carried out under different agitation (100 to 200 rpm) and aeration (V flask/V medium ratio varying from 2.5 to 5.0) conditions, and the influence of these variables on the fermentative parameters values (ethanol yield factor, Y P/S; cell yield factor, Y X/S; and ethanol volumetric productivity, Q P) was investigated through a 22 full-factorial design. Initial xylose concentration of about 50 g/l was the most suitable for the development of this process, since the yeast was able to convert substrate in product with high efficiency. The factorial design assays showed a strong influence of both process variables in all the evaluated responses. The agitation and aeration increase caused a deviation in the yeast metabolism from ethanol to biomass production. The best results (Y P/S = 0.37 g/g and Q P = 0.39 g/l.h) were found when the lowest aeration (2.5 V flask/V medium ratio) and highest agitation (200 rpm) levels were employed. Under this condition, a process efficiency of 72.5% was achieved. These results demonstrated that the establishment of adequate conditions of aeration is of great relevance to improve the ethanol production from xylose by Pichia stipitis, using rice straw hemicellulosic hydrolysate as fermentation medium.The financial support from Fapesp (Brazil) is gratefully acknowledged
STM and RHEED study of the Si(001)-c(8x8) surface
The Si(001) surface deoxidized by short annealing at T~925C in the ultrahigh
vacuum molecular beam epitaxy chamber has been in situ investigated by high
resolution scanning tunnelling microscopy (STM) and reflected high energy
electron diffraction (RHEED). RHEED patterns corresponding to (2x1) and (4x4)
structures were observed during sample treatment. The (4x4) reconstruction
arose at T<600C after annealing. The reconstruction was observed to be
reversible: the (4x4) structure turned into the (2x1) one at T>600C, the (4x4)
structure appeared again at recurring cooling. The c(8x8) reconstruction was
revealed by STM at room temperature on the same samples. A fraction of the
surface area covered by the c(8x8) structure decreased as the sample cooling
rate was reduced. The (2x1) structure was observed on the surface free of the
c(8x8) one. The c(8x8) structure has been evidenced to manifest itself as the
(4x4) one in the RHEED patterns. A model of the c(8x8) structure formation has
been built on the basis of the STM data. Origin of the high-order structure on
the Si(001) surface and its connection with the epinucleation phenomenon are
discussed.Comment: 26 pages, 12 figure
Breast Cancer Exosome-like Microvesicles and Salivary Gland Cells Interplay Alters Salivary Gland Cell-Derived Exosome-like Microvesicles In Vitro
Saliva is a useful biofluid for the early detection of disease, but how distal tumors communicate with the oral cavity and create disease-specific salivary biomarkers remains unclear. Using an in vitro breast cancer model, we demonstrated that breast cancer-derived exosome-like microvesicles are capable of interacting with salivary gland cells, altering the composition of their secreted exosome-like microvesicles. We found that the salivary gland cells secreted exosome-like microvesicles encapsulating both protein and mRNA. We also showed that the interaction with breast cancer-derived exosome-like microvesicles communicated and activated the transcriptional machinery of the salivary gland cells. Thus, the interaction altered the composition of the salivary gland cell-derived exosome-like microvesicles on both the transcriptomically and proteomically
On the costs and benefits of repeating a nonspatial feature in an exogenous spatial cuing paradigm
Geographic Variability in Access to Primary Kidney Transplantation in the United States, 1996–2005
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75057/1/j.1600-6143.2007.01785.x.pd
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