Sharif Digital Repository

Cometary activity is a manifestation of sublimation-driven processes at the surface of nuclei. However, cometary outbursts may arise from other processes that are not necessarily driven by volatiles. In order to fully understand nuclear surfaces and their evolution, we must identify the causes of cometary outbursts. In that context, we present a study of mini-outbursts of comet 46P/Wirtanen. Six events are found in our long-term lightcurve of the comet around its perihelion passage in 2018. The apparent strengths range from -0.2 to -1.6 mag in a 5″ radius aperture and correspond to dust masses between ∼104 and 106 kg, but with large uncertainties due to the unknown grain size distributions.... 

We present the study of a large sample of early-type dwarf galaxies in the Coma cluster observed with DEIMOS on the Keck II to determine their internal velocity dispersion. We focus on a subsample of 41 member dwarf elliptical galaxies for which the velocity dispersion can be reliably measured, 26 of which were studied for the first time. The magnitude range of our sample is -21 < M R < -15mag. This paper (Paper I) focuses on the measurement of the velocity dispersion and their error estimates. The measurements were performed using penalized pixel fitting (ppxf) and using the calcium triplet absorption lines. We use Monte Carlo bootstrapping to study various sources of uncertainty in our... 

We present a study of the Fundamental Plane (FP) for a sample of 71 dwarf galaxies in the core of the Coma cluster in the magnitude range -21 < M I < -15. Taking advantage of the high-resolution DEIMOS spectrograph on Keck II for measuring the internal velocity dispersion of galaxies and high-resolution imaging of the Hubble Space Telescope (HST)/ACS, which allows an accurate surface brightness modelling, we extend the FP of galaxies to luminosities of ~1 mag fainter than all the previous studies of the FP in the Coma cluster. We find that the scatter about the FP depends on the faint-end luminosity cut-off, such that the scatter increases for fainter galaxies. The residual from the FP... 

We propose a design algorithm for VIPA-based OCOMA encoder used in WOM-compatible COMA networks based on the problem requirements. Analyzing this device by our previous formulation leads to some useful suggestions to improve the device  

Artificial neural networks (ANN) have not been used in chronic subdural hematoma (CSDH) outcome prediction following surgery. We used two methods, namely logistic regression and ANN, to predict using eight variables CSDH outcome as assessed by the Glasgow outcome score (GOS) at discharge. We had 300 patients (213 men and 87 women) and potential predictors were age, sex, midline shift, intracranial air, hematoma density, hematoma thickness, brain atrophy, and Glasgow coma score (GCS). The dataset was randomly divided to three subsets: (1) training set (150 cases), (2) validation set (75 cases), and (3) test set (75 cases). The training and validation sets were combined for regression... 

Background: A small amount of methanol is produced endogenously in the human body but it is efficiently metabolized by alcohol dehydrogenase (ADH) and other enzymes, and the products eliminated without harm. In this study, we present a new entity of inborn error of methanol metabolism due to a mutation in the ADH1C gene coding for the γ subunit that is part of several ADH isoenzymes. Results: This disorder was discovered in an 11.58-year-old boy. During one 9-month hospital admission, he had periods of 1–4 days during which he was comatose, and between these periods he was sometimes verbose and euphoric, and had ataxia, dysarthria. Following hemodialysis treatments, he became conscious and...