5,269 research outputs found
Threshold value of three dimensional bootstrap percolation
The following article deals with the critical value p_c of the
three-dimensional bootstrap percolation. We will check the behavior of p_c for
different lengths of the lattice and additionally we will scale p_c in the
limit of an infinite lattice.Comment: 8 pages including 9 figures for Int.J.Mod.Phys.
Multidimensional Consensus model on a Barabasi-Albert network
A Consensus Model according to Deffuant on a directed Barabasi-Albert network
was simulated. Agents have opinions on different subjects. A multi-component
subject vector was used. The opinions are discrete. The analysis regards
distribution and clusters of agents which are on agreement in the opinions of
the subjects. Remarkable results are on the one hand, that there mostly exists
no absolute consens. It determines depending on the ratio of number of agents
to the number of subjects, whether the communication ends in a consens or a
pluralism. Mostly a second robust cluster remains, in its size depending on the
number of subjects. Two agents agree either in (nearly) all or (nearly) no
subject. The operative parameter of the consens-formating-process is the
tolerance in change of views of the group-members.Comment: 14 pages including all 10 figures, for IJMPC 16, issue
Overview of bladder heating technology: matching capabilities with clinical requirements.
Moderate temperature hyperthermia (40-45°C for 1 h) is emerging as an effective treatment to enhance best available chemotherapy strategies for bladder cancer. A rapidly increasing number of clinical trials have investigated the feasibility and efficacy of treating bladder cancer with combined intravesical chemotherapy and moderate temperature hyperthermia. To date, most studies have concerned treatment of non-muscle-invasive bladder cancer (NMIBC) limited to the interior wall of the bladder. Following the promising results of initial clinical trials, investigators are now considering protocols for treatment of muscle-invasive bladder cancer (MIBC). This paper provides a brief overview of the devices and techniques used for heating bladder cancer. Systems are described for thermal conduction heating of the bladder wall via circulation of hot fluid, intravesical microwave antenna heating, capacitively coupled radio-frequency current heating, and radiofrequency phased array deep regional heating of the pelvis. Relative heating characteristics of the available technologies are compared based on published feasibility studies, and the systems correlated with clinical requirements for effective treatment of MIBC and NMIBC
LANDSAT image differencing as an automated land cover change detection technique
Image differencing was investigated as a technique for use with LANDSAT digital data to delineate areas of land cover change in an urban environment. LANDSAT data collected in April 1973 and April 1975 for Austin, Texas, were geometrically corrected and precisely registered to United States Geological Survey 7.5-minute quadrangle maps. At each pixel location reflectance values for the corresponding bands were subtracted to produce four difference images. Areas of major reflectance differences are isolated by thresholding each of the difference images. The resulting images are combined to obtain an image data set to total change. These areas of reflectance differences were found, in general, to correspond to areas of land cover change. Information on areas of land cover change was incorporated into a procedure to mask out all nonchange areas and perform an unsupervised classification only for data in the change areas. This procedure identified three broad categories: (1) areas of high reflectance (construction or extractive), (2) changes in agricultural areas, and (3) areas of confusion between agricultural and other areas
A Spitzer View of the Young Open Cluster NGC 2264
We have performed mid-IR photometry of the young open cluster NGC 2264 using
the images obtained with the Spitzer Space Telescope IRAC and MIPS instruments
and present a normalized classification scheme of young stellar objects in
various color-color diagrams to make full use of the information from
multicolor photometry. These results are compared with the classification
scheme based on the slope of the spectral energy distribution (SED).
From the spatial distributions of Class I and II stars, we have identified
two subclusterings of Class I objects in the CONE region of Sung et al. The
disked stars in the other star forming region S MON are mostly Class II
objects. These three regions show a distinct difference in the fractional
distribution of SED slopes as well as the mean value of SED slopes. The
fraction of stars with primordial disks is nearly flat between log m = 0.2 --
-0.5, and that of transition disks is very high for solar mass stars. In
addition, we have derived a somewhat higher value of the primordial disk
fraction for NGC 2264 members located below the main pre-main sequence locus
(so-called BMS stars). This result supports the idea that BMS stars are young
stars with nearly edge-on disks. We have also found that the fraction of
primordial disks is very low near the most massive star S Mon and increases
with distance from S Mon.Comment: 38 pages, 21 figures, 5 tables (AJ accepted
Drift and trapping in biased diffusion on disordered lattices
We reexamine the theory of transition from drift to no-drift in biased
diffusion on percolation networks. We argue that for the bias field B equal to
the critical value B_c, the average velocity at large times t decreases to zero
as 1/log(t). For B < B_c, the time required to reach the steady-state velocity
diverges as exp(const/|B_c-B|). We propose an extrapolation form that describes
the behavior of average velocity as a function of time at intermediate time
scales. This form is found to have a very good agreement with the results of
extensive Monte Carlo simulations on a 3-dimensional site-percolation network
and moderate bias.Comment: 4 pages, RevTex, 3 figures, To appear in International Journal of
Modern Physics C, vol.
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