Browsing by Subject "BNL"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item Reducing Chatter in Knife-Edge Scanning Microscopy(2014-12-18) Shah, Raj SunilThe Knife-Edge Scanning Microscope (KESM) employs a novel form of physical sectioning microscopy: Imaging of tissue while sectioning. KESM was developed in the Brain Networks Lab (BNL) at Texas A&M University. The KESM has been used to section animal tissue embedded in a plastic block using a diamond knife. During each cut, the plastic block containing the tissue contacts the knife and that impact induces vibrations, known as knife chatter. These vibrations introduce noise in the image captured from the cut slice. This research is aimed at determining a metric to quantify knife chatter in the images acquired using the KESM, and to test if the use of a vibrating knife reduces knife chatter. Knife chatter appears as repeated parallel streaks in the images. A quantitative characterization of knife chatter is difficult since there is no regular pattern with which it appears. Having no regular pattern makes it very challenging to detect the chatter using automated programs. Observing the Fast Fourier Transforms of the images tells us that a narrow vertical band around the central vertical axis contains information exclusively about the chatter, while most of the information about the object in the image is outside the vertical band that represents the knife chatter. Using this information, we can quantitatively characterize knife chatter as a ratio of (1) the width of the region in the Fast Fourier Transform that corresponds to the knife chatter, and (2) the width of the region that corresponds to the object. Determining if the introduction of vibrations in the KESM diamond knife affects the amount of knife chatter present in the images was achieved by sectioning specimens of nissl-stained zebra-fish embryos embedded into araldite blocks, at different knife vibration frequencies. External sinusoidal wave vibrations were introduced in the KESM knife from a signal generator throughout the sectioning process. These electrical signals were converted to mechanical waves at the tip of the KESM knife blade. Performing such experiments at different oscillation frequencies enabled us to compare data using the metric described above. The results indicate that sectioning tissues with external vibrations does affect the amount of total data bandwidth taken up just by the chatter, and in some cases, reduces the relative width of the bandwidth taken up by the chatter.Item Two-particle correlations of identified particles in heavy ion collisions at STAR(2016-08) Bhattarai, Prabhat; Markert, Christina; Ray, Robert L. (Robert Landon); Bohm, Arno; Walker, Stephen; Onyisi, PeterThe study of quarks and their interactions through gluons has been an active area of research since their discovery. For two decades the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory has been dedicated to studying the interactions between quarks by producing nuclear matter in an extremely dense and hot environment. It has been hypothesized that colliding beams of atomic nuclei near the speed of light creates the hot and dense environment in which all quarks in the nuclei de-confine to form a short-lived state of matter called a Quark Gluon Plasma (QGP). Because of the short lifetime of QGP, it is impossible to observe it directly and, the only way to study such matter is through the final state particles. Two-particle correlation, which is defined using Pearson's normalized covariance, is one of the techniques to study the early interactions via the final state particles. A broad survey has been made to study the two-particle correlations of identified-charged hadrons (pi, K and p) in various ranges of momentum for the hadrons produced in √sNN=200 GeV Au+Au collisions at the STAR experiment at RHIC. A total of 2123 two-dimensional independent structures made by correlation coefficients in relative angular space in (eta, phi) for different combinations of identified hadrons have been studied. Correlations between any two identified particles contrasts to all-particle correlations giving an opportunity to study the contribution of each particle species in the hadronization processes. As a new feature, same-side anti-correlations are observed in both like-sign and unlike-sign pairs in certain yT bins and in certain identified particles. A significant feature of the final state distribution of particles is an azimuthal anisotropy which is defined as the second Fourier component; the amplitude is proportional to parameter v2. We report the measure of azimuthal anisotropy of identified hadrons for the first time and test for the factorization used in conventional analysis. The data presented here constitute a comprehensive measurement of the light-flavor, di-hadron density as function of collision centrality, transverse momentum and 2D relative angles in longitudinal (beam direction) and azimuthal directions.