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Problems and Solutions in a Graduate Course in Classical Electrodynamics (1)
Raza M. Syed
Physics , 2008,
Abstract: The following is the very first set of the series in 'Problems and Solutions in a Graduate Course in Classical Electrodynamics'. In each of the sets of the problems we intend to follow a theme, which not only makes it unique but also deals with the investigation of a certain class of problems in a thorough and rigorous manner. Figures are not included.
Suppression of Higgsino mediated proton decay by cancellations in GUTs and strings
Nath, Pran;Syed, Raza M.
High Energy Physics - Phenomenology , 2007, DOI: 10.1103/PhysRevD.77.015015
Abstract: A mechanism for the enhancement for proton lifetime in supersymmetric/supergravity (SUSY/SUGRA) grand unified theories (GUTs) and in string theory models is discussed where Higgsino mediated proton decay arising from color triplets (anti-triplets) with charges $Q=-1/3(1/3)$ and $Q=-4/3(4/3)$ is suppressed by an internal cancellation due to contributions from different sources. We exhibit the mechanism for an SU(5) model with $45_H+\bar{45}_H$ Higgs multiplets in addition to the usual Higgs structure of the minimal model. This model contains both $Q=-1/3(1/3)$ and $Q=-4/3(4/3)$ Higgs color triplets (anti-triplets) and simple constraints allow for a complete suppression of Higgsino mediated proton decay. Suppression of proton decay in an SU(5) model with Planck scale contributions is also considered. The suppression mechanism is then exhibited for an SO(10) model with a unified Higgs structure involving $144_H+\bar{144}_H$ representations.The SU(5) decomposition of $144_H+\bar{144}_H$ contains $5_H+\bar 5_H$ and $45_H+\bar{45}_H$ and the cancellation mechanism arises among these contributions which mirrror the SU(5) case. The cancellation mechanism appears to be more generally valid for a larger class of unification models. Specifically the cancellation mechanism may play a role in string model constructions to suppress proton decay from dimension five operators. The mechanism allows for the suppression of proton decay consistent with current data allowing for the possibility that proton decay may be visible in the next round of nucleon stability experiment.
Tiger Tales: A Critical Examination of the Tiger's Enclosure at the San Francisco Zoo
Erica Walker,Raza M. Syed
Physics , 2008,
Abstract: Given the recent tragedy involving a 350 pound Siberian Tiger and the death of teenager Carlos Souza Jr., one must ask a fundamental question: Can a tiger overcome an obstacle that is thirty-three feet away and twelve and a half feet tall? Are these dimensions sufficient enough to protect the zoo-visitors from a potential escape and/or attack? To answer these questions we use simple two-dimensional projectile motion to find the minimum velocity a tiger needs in order to clear the obstacle. With our results we conclude that it is highly likely that the tiger was able to leap over the obstacle with ease!
Analysis of Couplings with Large Tensor Representations in SO(2N) and Proton Decay
Pran Nath,Raza M. Syed
Physics , 2001, DOI: 10.1016/S0370-2693(01)00392-6
Abstract: We develop techniques for the analysis of SO(2N) invariant couplings which allow a full exhibition of the SU(N) invariant content of the spinor and tensor representations. The technique utilizes a basis consisting of a specific set of reducible SU(N) tensors in terms of which the SO(2N) invariant couplings have a simple expansion. The technique is specially useful for couplings involving large tensor representations. We exhibit the technique by performing a complete determination of the trilinear couplings in the superpotential for the case of SO(10) involving the 16 plet of matter, i.e., we give a full determination of the ${16-16-10_s}$, ${16-16-120_a}$ and ${16-16-\bar{126}_s}$ couplings. The possible role of large tensor representations in the generation of quark lepton textures is discussed. It is shown that the couplings involving $\bar{126}$ dimensional representation generate extra zeros in the Higgs triplet textures which can lead to an enhancement of the proton decay lifetime by a factor of $10^3$. These results also have implications for neutrino mass textures.
Complete Cubic and Quartic Couplings of 16 and $\bar {16}$ in SO(10) Unification
Pran Nath,Raza M. Syed
Physics , 2001, DOI: 10.1016/S0550-3213(01)00493-X
Abstract: A recently derived basic theorem on the decomposition of SO(2N) vertices is used to obtain a complete analytic determination of all SO(10) invariant cubic superpotential couplings involving $16_{\pm}$ semispinors of SO(10) chirality $\pm$ and tensor representations. In addition to the superpotential couplings computed previously using the basic theorem involving the 10, 120 and $\bar{126}$ tensor representations we compute here couplings involving the 1, 45 and 210 dimensional tensor representations, i.e., we compute the $\bar{16}_{\mp}16_{\pm}1$,$\bar{16}_{\mp}16_{\pm}45$ and $\bar{16}_{\mp}16_{\pm}210$ Higgs couplings in the superpotential. A complete determination of dimension five operators in the superpotential arising from the mediation of the 1, 45 and 210 dimensional representations is also given. The vector couplings $\bar{16}_{\pm}16_{\pm}1$, $\bar{16}_{\pm}16_{\pm}45$ and $\bar{16}_{\pm}16_{\pm}210$ are also analyzed. The role of large tensor representations and the possible application of results derived here in model building are discussed.
Areal Optimization of Polygons
Erica Walker,Raza M. Syed,Achille Corsetti
Mathematics , 2004,
Abstract: We will first solve the following problem analytically: given a piece of wire of specified length, we will find where the wire should be cut and bent to form two regular polygons not necessarily having the same number of sides, so that the combined area of the polygons thus formed is maximized, minimized, greater than, and less than a specified area. We will extend the results to the cases where the wire is divided into three and finally into an arbitrary number of segments. The second problem we will solve is as follows: two wires of specified length are to be bent into two regular polygons whose total number of sides is fixed. We will determine how the total number of polygonal sides are to be allocated between the wires so that the total area of the polygons is maximized. We will extend the results found here to the case where we are given any number of wires of specified length.
Authors′ Reply
Tayeb M,Raza Syed,Khan M,Azami R
Journal of Postgraduate Medicine , 2005,
Abstract:
Conversion from laparoscopic to open cholecystectomy: Multivariate analysis of preoperative risk factors
Tayeb M,Raza Syed,Khan M,Azami R
Journal of Postgraduate Medicine , 2005,
Abstract: BACKGROUND: Laparoscopic cholecystectomy has become the gold standard in the treatment of symptomatic cholelithiasis. Some patients require conversion to open surgery and several preoperative variables have been identified as risk factors that are helpful in predicting the probability of conversion. However, there is a need to devise a risk-scoring system based on the identified risk factors to (a) predict the risk of conversion preoperatively for selected patients, (b) prepare the patient psychologically, (c) arrange operating schedules accordingly, and (d) minimize the procedure-related cost and help overcome financial constraints, which is a significant problem in developing countries. AIM: This study was aimed to evaluate preoperative risk factors for conversion from laparoscopic to open cholecystectomy in our setting. SETTINGS AND DESIGNS: A case control study of patients who underwent laparoscopic surgery from January 1997 to December 2001 was conducted at the Aga Khan University Hospital, Karachi, Pakistan. MATERIALS AND METHODS: All those patients who were converted to open surgery (n = 73) were enrolled as cases. Two controls who had successful laparoscopic surgery (n = 146) were matched with each case for operating surgeon and closest date of surgery. STATISTICAL ANALYSIS USED: Descriptive statistics were computed and, univariate and multivariate analysis was done through multiple logistic regression. RESULTS: The final multivariate model identified two risk factors for conversion: ultrasonographic signs of inflammation (adjusted odds ratio [aOR] = 8.5; 95% confidence interval [CI]: 3.3, 21.9) and age > 60 years (aOR = 8.1; 95% CI: 2.9, 22.2) after adjusting for physical signs, alkaline phosphatase and BMI levels. CONCLUSION: Preoperative risk factors evaluated by the present study confirm the likelihood of conversion. Recognition of these factors is important for understanding the characteristics of patients at a higher risk of conversion.
QUANTITATIVE DETERMINATION OF ANTIOXIDANT POTENTIAL OF ARTEMISIA PERSICA
Ayoub Rashid,M. Zahid Qureshi,Syed Ali Raza,J. William
Analele Universitatii Bucuresti : Chimie , 2010,
Abstract: An experimental protocol was designed to investigate the total flavonoids, phenolics and antioxidant potential of methanol extract of Artemisia persica. For initial screening of antioxidant activity DPPH on TLC was employed. After the qualitative confirmation of antioxidant potential, spectroscopic measurements were made through DPPH assay. Free fatty acids (FFA), Peroxide values (PV) and Iodine values were monitored in refined, bleached and deodorized (RBD) sunflower oil. Plant extract was found to possess strong antioxidant potential in all mentioned assays. Total phenolic and flavonoid contents were 407 mg/g and 308 mg/g respectively.
Applications of Quantum Physics on Resistivity, Dielectricity, Giant Magneto Resistance, Hall Effect and Conductance  [PDF]
Saleem Iqbal, Farhana Sarwar, Syed Masood Raza, Syed Mohsin Raza
World Journal of Condensed Matter Physics (WJCMP) , 2016, DOI: 10.4236/wjcmp.2016.62013
Abstract: Quantum theory with conjecture of fractional charge quantization, eigenfunctions for fractional charge quantization, fractional Fourier transform, Hermite function for fractional charge quantization, and eigenfunction for a twisted and twigged electron quanta is developed and applied to resistivity, dielectricity, giant magneto resistance, Hall effect and conductance. Our theoretical relationship for quantum measurements is in good conformity and in agreement with most of the experimental results. These relationships will pave a new approach to quantum physics for deciphering measurements on single quantum particles without destroying them. Our results are in agreement with 2012 Physics Nobel Prize winning Scientists, Serge Haroche and David J. Wineland.
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