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Mathematical Model: Comparative Study of Thermal Effects of Laser in Corneal Refractive Surgeries
Get PDFLasers have been widely used in ophthalmology. Refractive errors are some of the most common ophthalmic abnormalities worldwide. Laser refractive surgery was developed to correct refractive errors myopia, hyperopia and astigmatism. Two types of laser surgical techniques: lamellar and thermal are available to reshape the corneal curvature. Ultraviolet (UV) emitting argon fluoride (ArF) excimer laser is used to sculpt cornea in lamellar procedures, whereas, infrared (IR) emitting holmium yttrium aluminum garnet (Ho: YAG) laser is used to shrink cornea in thermal procedure. Tissue heating is common in all types of laser surgical techniques. Hence, in this paper, a finite element model is developed to investigate the temperature distribution of cornea in different laser refractive surgeries. Characteristics of optical and thermal processes and influence of the parameters of radiation and tissues on the results of laser action are investigated. The results of mathematical modeling in different surgical techniques are discussed, compared, and validated with experimental results
Local Fractional Variational Iteration Method for Solving Nonlinear Partial Differential Equations within Local Fractional Operators
Get PDFIn this article, the local fractional variational iteration method is proposed to solve nonlinear partial differential equations within local fractional derivative operators. To illustrate the ability and reliability of the method, some examples are illustrated. A comparison between local fractional variational iteration method with the other numerical methods is given, revealing that the proposed method is capable of solving effectively a large number of nonlinear differential equations with high accuracy. In addition, we show that local fractional variational iteration method is able to solve a large class of nonlinear problems involving local fractional operators effectively, more easily and accurately, and thus it has been widely applicable in engineering and physics
Solution to Some Open Problems on E-super Vertex Magic Total Labeling of Graphs
Get PDFLet G be a finite graph with p vertices and q edges. A vertex magic total labeling is a bijection f from V(G)∪E(G) to the consecutive integers 1, 2, ..., p+q with the property that for every u∈V(G) , f( u)+ ∑f(uv)=K for some constant k. Such a labeling is E-super if f :E(G)→{1, 2,..., q}. A graph G is called E-super vertex magic if it admits an E-super vertex magic labeling. In this paper, we solve two open problems given by Marimuthu, Suganya, Kalaivani and Balakrishnan (Marimuthu et al., 2015)
The behavioral roots of information systems security: Exploring key factors related to unethical IT use
No full textUnethical information technology (IT) use, related to activities such as hacking, software piracy, phishing, and spoofing, has become a major security concern for individuals, organizations, and society in terms of the threat to information systems (IS) security. While there is a growing body of work on this phenomenon, we notice several gaps, limitations, and inconsistencies in the literature. In order to further understand this complex phenomenon and reconcile past findings, we conduct an exploratory study to uncover the nomological network of key constructs salient to this phenomenon, and the nature of their interrelationships. Using a scenario-based study of young adult participants, and both linear and nonlinear analyses, we uncover key nuances of this phenomenon of unethical IT use. We find that unethical IT use is a complex phenomenon, often characterized by nonlinear and idiosyncratic relationships between the constructs that capture it. Overall, ethical beliefs held by the individuals, along with economic, social, and technological considerations are found to be relevant to this phenomenon. In terms of practical implications, these results suggest that multiple interventions at various levels may be required to combat this growing threat to IS security
Wetness conditions and redoximorphic features in a microtoposequence on the Texas Coast Prairie
No full textThe purpose of this study was to investigate the relationship between wetness conditions and redoximorphic features in three soils that occur on adjacent microtopographic landform positions. The landform positions included a closed, seasonally ponded depression, and intermound, and a pimple mound. Aquic conditions as defined by the Keys to Soil Taxonomy (Soil Surv. Staff, 1996) were assessed by: (i) redoximorphic features, and (ii) measurement of saturation and reduction to verify morphological features used to infer aquic conditions. Taxonomic classification of the three pedons representing the toposequence were: (i) mound (fine-loamy, siliceous, thermic Oxyaquic Paleudalfs), (ii) intermound (coarse-loamy, siliceous, thermic Typic Natraqualfs, and (iii) depression (fine-loamy, siliceous, thermic Typic Endoaqualfs). The soil sites were located northwest of Houston near the city of Cypress in Harris County on the Katy Prairie portion of the central Texas Gulf Coast Prairie. The three sites represent the upper, middle, and lower topographic positions on this landscape. During a 19-mo period, each of the different landform positions exhibited different perched and groundwater piezometric surfaces within the upper 200 cm. During periods of saturation, low oxidation-reduction potentials (≤ 120 mV in the intermound and \u3c240 mV in the depression) suggested that Fe reduction occurred in the soils. The intermound was saturated at the surface and below 100 cm that corresponded closely with decreased water movement within the portion of the soil profile where a natric horizon occurred between 26 and 136 cm. The depression site exhibited saturation during the fall to spring and Fe reduction in the profile, so redox features were associated with current and possibly with relict aquic conditions
Dividend payouts of commercial banks
No full textIn this paper, we examine relations between a bank\u27s dividend payouts and stock and option holdings of the top five executives. We find a negative relation between dividend payouts and stock option holdings although the relation becomes significantly weaker after the enactment of Gramm-Leach-Bliley in 1999 and the dividend tax cut in 2003. We also find that dividend payouts are negatively related to managerial stock holdings prior to the dividend tax cut but this relation becomes significantly positive in the post dividend tax cut regime. This is consistent with firms increasing dividend payments for firms with executives with large stock holding in the post tax cut regime
Porous PCL/Chitosan and nHA/PCL/chitosan scaffolds for tissue engineering applications: Fabrication and evaluation
No full textTwo semicrystalline polymers were blended to fabricate porous scaffolds for tissue engineering applications. Scaffolds containing polycaprolactone (PCL)/chitosan and nanohydroxyapatite (nHA) incorporated nHA/PCL/chitosan were produced using the freeze-drying technique. A model drug, tetracycline hydrochloride (tetracycline HCL), was incorporated into the scaffolds. The scaffolds were characterized using a scanning electron microscope (SEM), EDX, and water contact angle. The antibacterial properties of the nHA/PCL/chitosan/tetracycline HCL scaffold were tested and the scaffolds showed positive results on gram-positive and gram-negative bacteria. The cell biocompatibility using human skin fibroblast cells (HSF 1184) was examined. The scaffold materials were found to be nontoxic to human skin fibroblast cells (HSF 1184) and showed positive proliferation activities. The nHA/PCL/chitosan/tetracycline HCL scaffold has potential for controlling implant-associated bacterial infections during operative procedures and can potentially be used as a scaffold for tissue engineering applications
Rainfall-runoff modeling in a flashy tropical watershed using the distributed HL-RDHM model
No full textMany watersheds in Hawai\u27i are flash flood prone due to their small contributing areas and frequent intense rainfall. Motivated by the possibility of developing an operational flood forecasting system, this study evaluated the performance of the National Weather Service (NWS) model, the Hydrology Laboratory Research Distributed Hydrologic Model (HL-RDHM) in simulating the hydrology of the flood-prone Hanalei watershed in Kaua\u27i, Hawai\u27i. This rural watershed is very wet and has strong spatial rainfall gradients. Application of HL-RDHM to Hanalei watershed required (i) modifying the Hydrologic Rainfall Analysis Project (HRAP) coordinate system; (ii) generating precipitation grids from rain gauge data, and (iii) generating parameters for Sacramento Soil Moisture Accounting Model (SAC-SMA) and routing parameter grids for the modified HRAP coordinate system. Results were obtained for several spatial resolutions. Hourly basin-average rainfall calculated from one HRAP resolution grid (4km×4km) was too low and inaccurate. More realistic rainfall and more accurate streamflow predictions were obtained with the 1/2 and 1/4 HRAP grids. For a one year period with the best precipitation data, the performance of HL-RDHM was satisfactory even without calibration for basin-averaged and distributed a priori parameter grids. Calibration and validation of HL-RDHM were conducted using four-year data set each. The model reasonably matched the observed peak discharges and time to peak during calibration and validation periods. The performance of model was assessed using the following three statistical measures: Root Mean Square Error (RMSE), Nash-Sutcliffe efficiency (NSE) and Percent bias (PBIAS). Overall, HL-RDHM\u27s performance was very good (NSE\u3e0.75, PBIAS\u3c±10) for the finer resolution grids (1/2 HRAP or 1/4 HRAP). The quality of flood forecasting capability of the model was accessed using four accuracy measures (probability of false detection, false alarm ratio, critical success index, and probability of detection) for three return periods 1.005, 1.05 and 1.25. HL-RDHM is more accurate at the lower threshold discharge (65m3s-1) than at the higher ones (140 and 248m3s-1) as indicated by lower values of probability of detection and critical success index, and a higher value of the false alarm ratio. These results suggest that HL-RDHM may be suitable for flood forecasting applications in watersheds with steep terrain and strong spatio-temporal variability of precipitation, e.g. US Pacific North-West, and tropical islands
Soil moisture retrieval using ground-based L-band passive microwave observations in northeastern USA
No full textA field experiment was performed in a grassland at the NOAA-CREST-Soil Moisture Advanced Radiometric Testbed (CREST-SMART) facility, which includes a mobile L-band dual-polarized radiometer with an in situ soil temperature and soil moisture observation network, located near Millbrook, NY. During the day-long field campaign, intensive spatiotempora measurements of L-band brightness temperatures, surface temperature, soil moisture, and soil temperature at 3-, 7-, and 12-cm depths were collected during three passes at 0830, 1130, and 1430 h. During the second and third passes, half of the field was irrigated. Soil roughness and water content of the short grass that remained after mowing the study area were measured. The Tau-Omega radiative transfer model was used to assess the performance of the soil moisture retrieval using measured soil temperatures at different depths. In addition, the collected microwave observations at the three different times of the day were used to assess the impact of the diurnal variation of soil temperature on the performance of soil moisture retrieval. Obtained results showed that the root mean square error (RMSE) decreased throughout the day to reach 0.03 m3/m3 for the afternoon pass when 12-cm soil temperature values were used in the radiative transfer model. In addition, during the three different passes, the lowest RMSE was consistently obtained when the 12-cm soil temperature was used, which suggests that, for this investigated site, soil temperature at the 12-cm depth can be a surrogate for soil effective temperature when L-band microwave temperatures are used. In terms of diurnal variability, observations from the afternoon pass led to the highest agreement between observed and retrieved soil moisture values. © Soil Science Society of America
On Some Hadamard-Type Inequalıtıes for (r,m) -Convex Functıons
Get PDFIn this paper, we define a new class of convex functions which is called (r,m) - convex functions. We also prove some Hadamard\u27s type inequalities based on this new definition