Effect of Unfolding on the Spectral Statistics of Adjacency Matrices of Complex Networks

Random matrix theory is finding an increasing number of applications in the context of information theory and communication systems, especially in studying the properties of complex networks. Such properties include short-term and long-term correlation. We study the spectral fluctuations of the adjacency of networks using random-matrix theory. We consider the influence of the spectral unfolding, which is a necessary procedure to remove the secular properties of the spectrum, on different spectral statistics. We find that, while the spacing distribution of the eigenvalues shows little sensitivity to the unfolding method used, the spectral rigidity has greater sensitivity to unfolding.Comment: Complex Adaptive Systems Conference 201

Empirical Study of Traffic Velocity Distribution and its Effect on VANETs Connectivity

In this article we use real traffic data to confirm that vehicle velocities follow Gaussian distribution in steady state traffic regimes (free-flow, and congestion). We also show that in the transition between free-flow and congestion, the velocity distribution is better modeled by generalized extreme value distribution (GEV). We study the effect of the different models on estimating the probability distribution of connectivity duration between vehicles in vehicular ad-hoc networks.Comment: 5 pages, 5 figures, presented at the ICCVE 2014 (International conference on connected vehicles & expo); http://www.iccve.org

Nuclear Medium Effects in the Relativistic Treatment of Quasifree Electron Scattering

Non-relativistic reduction of the S-matrix for the quasifree electron scattering process $A\left(~e, e'p~\right)A-1$ is studied in order to understand the source of differences between non-relativistic and relativistic models. We perform an effective Pauli reduction on the relativistic expression for the S-matrix in the one-photon exchange approximation. The reduction is applied to the nucleon current only; the electrons are treated fully relativistically. An expansion of the amplitude results in a power series in the nuclear potentials. The series is found to converge rapidly only if the nuclear potentials are included in the nuclear current operator. The results can be cast in a form which reproduces the non-relativistic amplitudes in the limit that the potentials are removed from the nuclear current operator. Large differences can be found between calculations which do and do not include the nuclear potentials in the different orders of the nuclear current operator. In the high missing momentum region we find that the non-relativistic calculations with potentials included in the nuclear current up to second order give results which are close to those of the fully relativistic calculation. This behavior is an indication of the importance of the medium modifications of the nuclear currents in this model, which are naturally built into the relativistic treatment of the reaction.Comment: Latex, 26 pages including 5 uuencoded postscript figures. accepted for publication in Phys. Rev. C

One-Year Results of Simultaneous Topography-Guided Photorefractive Keratectomy and Corneal Collagen Cross-Linking in Keratoconus Utilizing a Modern Ablation Software

Purpose. To evaluate effectiveness of simultaneous topography-guided photorefractive keratectomy and corneal collagen cross-linking in mild and moderate keratoconus. Methods. Prospective nonrandomized interventional study including 20 eyes of 14 patients with grade 1-2 keratoconus that underwent topography-guided PRK using a Custom Ablation Transition Zone (CATz) profile with 0.02% MMC application immediately followed by standard 3 mw/cm2 UVA collagen cross-linking. Maximum ablation depth did not exceed 58 μm. Follow-up period: 12 months. Results. Progressive statistically significant improvement of UCVA from 0.83±0.37 logMAR preoperative, reaching 0.25±0.26 logMAR at 12 months (P<0.001). Preoperative BCVA (0.27±0.31 logMAR) showed a progressive improvement reaching 0.08±0.12 logMAR at 12 months (P=0.02). Mean Kmax reduced from 48.9±2.8 to 45.4±3.1 D at 12 months (P<0.001), mean Kmin reduced from 45.9±2.8 D to 44.1±3.2 D at 12 months (P<0.003), mean keratometric asymmetry reduced from 3.01±2.03 D to 1.25±1.2 D at 12 months (P<0.001). The safety index was 1.39 at 12 months and efficacy index 0.97 at 12 months. Conclusion. Combined topography-guided PRK and corneal collagen cross-linking are a safe and effective option in the management of mild and moderate keratoconus. Precis. To our knowledge, this is the first published study on the use of the CATz ablation system on the Nidek Quest excimer laser platform combined with conventional cross-linking in the management of mild keratoconus

Analytical solution to a sea-water intrusion problem with a fresh water zone tapering to a triple point

A new explicit analytical solution is obtained to a steady-state abrupt interface problem concerning sea-water intrusion into a coastal unconfined homogeneous aquifer with a horizontal impermeable bed and uniformly distributed losses along a phreatic surface. Two free surfaces (encroachment tongue and groundwater table) intersect with a horizontal water table of the resting sea water propagated inland. In the hodograph plane the image of the physical domain is a curvilinear triangle. Conformal mappings of the physical domain and of an unknown complex-potential domain onto an auxiliary half-plane are obtained by a modified method of Polubarinova-Kochina, which is mathematically reduced to a vector Riemann boundary-value problem. Free surfaces are reconstructed for different values of losses, densities of the two fluids, sea water and incident groundwater hydraulic heads. Comparisons with the Dupuit-Forcheimer (hydraulic) model are made and practical implications for catchment-scale groundwater management in Oman and UAE are discussed. © Springer 2006

Cataract prevalence following a nationwide policy to shorten wait time for cataract surgery

Background: Cataract is an age-related eye disease. Visual impairment from cataract can be restored by cataract surgery. In 2004 the Canadian federal government invested in a multibillion dollar wait time strategy to shorten the wait time for cataract surgery, a government-insured health service in all Canadian jurisdictions. We assessed if this nationwide policy reduced the number of Canadians waiting for cataract surgery as more individuals with cataract were free of cataract following the rapidly conducted surgery. Methods: In this cross-sectional study we analyzed data from randomly selected individuals aged greater than or equal to 45 years responding to the Canadian Community Health Survey (CCHS) in 2000/2001, 2003, 2005, and the CCHS Healthy Aging in 2008/2009. Information on cataract was obtained from self-reported questionnaire. The age- and sex-standardized prevalence of cataract was calculated for comparisons. Results: Cataract was reported by 0.93 million Canadians in 2000/2001, 0.99 million in 2003, 1.10 million in 2005, and 1.34 million in 2008/2009. This corresponds to an age- and sex-standardized prevalence of 8.9% in 2000/2001, 9.0% in 2003, 9.5% in 2005, and 10.2% (P &lt;0.05) in 2008/2009. The increase in age- and sex-standardized prevalence was greater in individuals without secondary school graduation than those with secondary school graduation or higher (4.3% versus 1.3%, P &lt; 0.05) and was seen in all Canadian provinces. The largest increase was documented in a province (Saskatchewan, from 9.8% in 2000/2001 to 12.6% in 2008/2009, P &lt; 0.05) with the longest median wait times for cataract surgery (118 days in 2008) and the lowest number of ophthalmologists per 100,000 population (1.96 versus 3.35 national average). Conclusions: The age- and sex-standardized prevalence of cataract increased 4-5 years after the multibillion-dollar wait time strategy was launched in 2004. A lower threshold to diagnose cataract may be one potential reason for this finding. Further research is needed to understand the true reasons for the increase

Sources and Mitigation of Harmonics in Industrial Electrical Power Systems: State of the Art

Abstract -Power systems are designed to operate at frequencies of 50 Hz or 60Hz. However, certain types of loads produce currents and voltages with frequencies that are integer multiples of the 50 or 60 Hz fundamental frequency. These higher frequencies represent a form of electrical network pollutions known as &apos;&apos;power system harmonics&apos;&apos;. This paper presents an extensive literature review in the petrochemical sector for the power system harmonics such as harmonics fundamentals, harmonics harmful effects on various electrical equipment, harmonic distortion limits and harmonic mitigation techniques. This paper is intended as a guide for those interested in this problem or intending to perform further researches in this area

Study of the Urinary Ratio of 6 β-Hydroxycortisol/Cortisol as a Biomarker of CYP3A4 Activity in Egyptian Patients with Chronic Liver Diseases

The urinary ratio of 6 β-hydroxycortisol/cortisol (6 β-OHC/C) as a biomarker of CYP3A4 metabolizing activity has been studied in Egyptian patients with chronic liver cirrhosis associated with previous hepatic Schistosomiasis infection to determine any possible alteration in enzyme activity. The ratio of 6-β OHC/C was determined in morning urine samples collected from 8:00 a.m. to 12:00 p.m. in healthy adults (n = 36) and patients with liver cirrhosis (n = 57). The median age for control was 27 years (range: 18–50 years) and 50 years (range: 27–75 years) for patients. 6 β-OHC was detected in urine by ELIZA kits (Stabiligen, France). Patients with liver cirrhosis were categorized according to Child Pugh Classification into Child B (n = 28) and Child C (n = 29) classes. Cholestasis was observed in 9/28 of Child B class and 8/29 of Child C class of patients. The control subjects showed gender-related difference in the urinary ratio of 6 β-OHC/C. A significant reduction (P < 0.001) in 6 β-OHC/C ratio was observed only in Child C patients in comparison with control subjects. Regression analysis showed a significant correlation (P < 0.05) between 6 β-OHC/C ratio and serum albumin. The influence of cholestasis on the urinary ratio of 6-β OHC/C was observed on cirrhotic patients of Child B class. In conclusion, patients with chronic liver cirrhosis might have a reduction of metabolizing activity of CYP3A4 enzymes which could be identified by measuring the urinary ratio of 6 β-OHC/C. This reduction is more apparent in severe liver injury (Child C class). Therefore, it is important to understand the metabolic fate of drugs metabolized by 3A4 enzymes in patients with liver cirrhosis to avoid drug accumulation that might lead to development of drug toxicity