CfA Plasma Talks

Notes from a series of 13 one hour (or more) lectures on Plasma Physics given to Ramesh Narayan' research group at the Harvard-Smithsonian Center for Astrophysics, between January and July 2012. Lectures 1 to 5 cover various key Plasma Physics themes. Lectures 6 to 12 mainly go over the Review Paper on "Multidimensional electron beam-plasma instabilities in the relativistic regime" [\emph{Physics of Plasmas} \textbf{17}, 120501 (2010)]. Lectures 13 talks about the so-called Biermann battery and its ability to generate magnetic fields from scratch.Comment: 58 pages, 21 figure

Femoral artery ultrasound examination: a new role in predicting cardiovascular risk

We compared intima-media thickness (IMT) and the prevalence of plaques in the common carotid artery (CCA) and common femoral artery (CFA) in apparently healthy participants. This multicenter study included 322 participants (59.9% female; age 20-78 years, mean 52.1 ± 15.3 years) who underwent Echo-color Doppler examination of the CCA and CFA bilaterally. Prevalence and composition of plaque were recorded. A significant ( P < .01) difference between mean CCA-IMT and mean CFA-IMT was detected (0.70 vs 0.73 mm). Plaque prevalence was significantly higher in the CFA compared to the CCA (40.7% vs 30.4%). Atherosclerotic plaques were found in both CFA and CCA in 46% of the cases, solely in CFA in 38%, and in CCA alone in 17%. The observed difference in plaque prevalence was even greater when only fibrolipid isolated plaques were considered (CFA 39.4% vs CCA 22.1%). In a healthy general population, atherosclerotic plaques were present in the CFA but not in the CCA in over one-third of the cases. Further studies must confirm whether ultrasonography of the CFA might be introduced in the screening protocols for cardiovascular risk assessment

The effect of the color filter array layout choice on state-of-the-art demosaicing

Interpolation from a Color Filter Array (CFA) is the most common method for obtaining full color image data. Its success relies on the smart combination of a CFA and a demosaicing algorithm. Demosaicing on the one hand has been extensively studied. Algorithmic development in the past 20 years ranges from simple linear interpolation to modern neural-network-based (NN) approaches that encode the prior knowledge of millions of training images to fill in missing data in an inconspicious way. CFA design, on the other hand, is less well studied, although still recognized to strongly impact demosaicing performance. This is because demosaicing algorithms are typically limited to one particular CFA pattern, impeding straightforward CFA comparison. This is starting to change with newer classes of demosaicing that may be considered generic or CFA-agnostic. In this study, by comparing performance of two state-of-the-art generic algorithms, we evaluate the potential of modern CFA-demosaicing. We test the hypothesis that, with the increasing power of NN-based demosaicing, the influence of optimal CFA design on system performance decreases. This hypothesis is supported with the experimental results. Such a finding would herald the possibility of relaxing CFA requirements, providing more freedom in the CFA design choice and producing high-quality cameras

Oxidation of clofibric acid in aqueous solution using a non-thermal plasma discharge or gamma radiation

In this work, we study degradation of clofibric acid (CFA) in aqueous solution using either ionizing radiation from a $^{60}$Co source or a non-thermal plasma produced by discharges in the air above the solution. The results obtained with the two technologies are compared in terms of effectiveness of CFA degradation and its by-products. In both cases the CFA degradation follows a quasi-exponential decay in time well modelled by a kinetic scheme which considers the competition between CFA and all reaction intermediates for the reactive species generated in solution as well as the amount of the end product formed. A new degradation law is deduced to explain the results. Although the end-product CO$_2$ was detected and the CFA conversion found to be very high under the studied conditions, HPLC analysis reveals several degradation intermediates still bearing the aromatic ring with the chlorine substituent. The extent of mineralization is rather limited. The energy yield is found to be higher in the gamma radiation experiments.Comment: 25 pages, 7 figure

Fixed parity of the exchange rate and economic performance in the CFA zone : a comparative study

The authors compare economic performance in the CFA (franc) zone with the economic performance in similar countries outside the CFA zone in recent years. The results of their model estimates indicate that the competitive position for CFA members was weaker in the second half of the 1980s than in the first half and weaker than in non-CFA countries in terms of output growth as well as the performance of exports, investment, and savings. The exception was domestic inflation: the CFA fared better on that front. Results for a longer-term comparison are somewhat mixed. The CFA zone performed better than the others in exports, domestic savings and investment, and inflation, but failed in the long run to distinguish itself in terms of economic growth. The authors use a modified control group approach to compare changes in macroeconomic indicators in the CFA countries with those in countries elsewhere in sub-Saharan Africa and similar low-income developing countries. They control for initial conditions, changing exogenous internal and world environment, and policy stance. Their approach allows for a formal testing of whether zone membership is a random choice. The implication of randomness is that the CFA zone economies would have performed the same as the rest of sub-Saharan Africa, for example, if there had been no zone. Their results show the assumption of randomness to be valid only for GDP growth and inflation.Economic Theory&Research,Environmental Economics&Policies,Economic Stabilization,Achieving Shared Growth,Financial Intermediation

PREDICTION-CFA PADA CFA REGIONAL

Banyak peneliti menggunakan data kategori pada penelitiannya. Salah satu metode yang digunakan adalah Analisis Konfigurasi Frekuensi. Pada analisis tersebut nantinya akan dilihat suatu pola konfigurasi apakah nilainya akan lebih besar dari yang diharapkan (type) atau lebih sedikit dari yang diharapkan (antitype). Analisis Konfigurasi Frekuensi adalah metode nonparametric yang digunakan untuk menunjukkan nilai suatu tanda/pola yang berbeda dari frekwensi yang ada pada analisis multivariate (Lienert, 1969; Krauth and Linert, 1973, 1982; Lienert dan Oeveste, 1985). Suatu pola yang terjadi lebih sering dari yang telah diekspektasikan disebut dengan type dan yang terjadi lebih jarang dari yang diekspektasikan disebut dengan antitype.Pada analisis variabel kategori, covariates dapat dijelaskan bersamaan dengan variabel yang terstratifikasi (Graham, 1995) serta dalam contoh lain, bisa juga dikatakan bahwa covariates adalah juga variabel kontinu. Penggunaan covariates biasanya menghasilkan frekwensi estimasi dari suatu sel yang nilainnya berdekatan dengan frekwensi yang diobservasi karena lebih banyak informasi yang digunakan dalam proses estimasi (Von Eye dan Niedermeier, 1999). Penelitian ini akan menggunakan metode Analisis Konfigurasi Frekuensi yang akan diaplikasikan pada categorical covariates dan dilakukan pada data yang terstratifikasi. Kata kunci: Prediction-CFA, CFA Regional, Data Kategor

The Updated Zwicky Catalog (UZC)

The Zwicky Catalog of galaxies (ZC), with m_Zw<=15.5mag, has been the basis for the Center for Astrophysics (CfA) redshift surveys. To date, analyses of the ZC and redshift surveys based on it have relied on heterogeneous sets of galaxy coordinates and redshifts. Here we correct some of the inadequacies of previous catalogs by providing: (1) coordinates with <~2 arcsec errors for all of the Nuzc catalog galaxies, (2) homogeneously estimated redshifts for the majority (98%) of the data taken at the CfA (14,632 spectra), and (3) an estimate of the remaining "blunder" rate for both the CfA redshifts and for those compiled from the literature. For the reanalyzed CfA data we include a calibrated, uniformly determined error and an indication of the presence of emission lines in each spectrum. We provide redshifts for 7,257 galaxies in the CfA2 redshift survey not previously published; for another 5,625 CfA redshifts we list the remeasured or uniformly re-reduced value. Among our new measurements, Nmul are members of UZC "multiplets" associated with the original Zwicky catalog position in the coordinate range where the catalog is 98% complete. These multiplets provide new candidates for examination of tidal interactions among galaxies. All of the new redshifts correspond to UZC galaxies with properties recorded in the CfA redshift compilation known as ZCAT. About 1,000 of our new measurements were motivated either by inadequate signal-to-noise in the original spectrum or by an ambiguous identification of the galaxy associated with a ZCAT redshift. The redshift catalog we include here is ~96% complete to m_Zw<=15.5, and ~98% complete (12,925 galaxies out of a total of 13,150) for the RA(1950) ranges [20h--4h] and [8h--17h] and DEC(1950) range [-2.5d--50d]. (abridged)Comment: 34 pp, 7 figs, PASP 1999, 111, 43