137 research outputs found
A Novel Generalized Scattering Through Heterostructure With A Time-Periodic Potential
Interaction with external time-dependent fields in low-dimensional systems leads in many cases to completely new phenomena of electronic transport. Dealing with a driven system, its quantum dynamics is adequately analyzed in terms of the Floquet or quasienergy spectrum. In this paper, we extend the effective mass model to the case of different effective masses for different materials in a heterostructure. For this case we present a general method which allows us to treat a time modulated potential acting upon a quantum well structure. We extend the work of Wenjun Li and LE Reichl,[1], and consider the case of a multilayer composed of different materials, assuming th
Magnetostatic surface waves propagation at the interface between ferrite and MTMs parallel plate waveguide structure
Accepted 10/6/2013 Abstract: This work considers magnetostatic surface waves propagation in parallel structure composed of ferrite film bounded from below by metamaterial (MTM) placed on metal substrate and from top by air. The Maxwell equations are used to analyse propagation of slow (magnetostatic) surface electromagnetic wave in this structure. Results show that magnetostatic surface wave (MSSW) propagates at certain range of frequencies and varies as both MTM layer and ferrite layer thicknesses change. The new behaviour of the proposed waveguide in the presence of MTM in particular the appearance of the unidirectional MSSW is promising for practical applications such as isolators
The Sensitivity of TE Filed Propagating in LHM-Antiferromagnetic Sensor
A three-layer waveguide structure sensor consists of LHMs (left-handed materials) film surrounded by dielectric cladding and antiferromagnetic substrate is proposed. LHMs known as MTMs (metamaterials) have simultaneous negative permeability and permittivity. The dispersion relation for the structure is derived for TE guided modes. Two ranges of frequencies are chosen such that Voigt permeability, μv, either negative or positive. The sensitivity is proven to be affected by different parameters including the film thickness, LHM parameters, and Voigt frequency
Propagation of Electromagnetic Surface Waves through a Ferrite Slab Bounded by Metamaterials
Recently there has been growing interest in a new type of electromagnetic materials called lefthanded materials (LHMs), or metamaterials. Over thirty years ago Veselago [1] predicted that electromagnetic wave propagation in a medium having simultaneously negative permittivity ε and permeability μ should give rise to several peculiar characteristics. Veselago predicted that in LHM the energy flow (Pointing vector) is anti-parallel to the phase velocity (or wave vector) while in regular materials termed right-handed materials (RHMs), having simultaneously positive ε and μ the Pointing vector (energy flow) gives the direction of the phase velocity. In this communication, the dispersion relationship describing the propagation of electromagnetic surface modes supported by a finite thickness ferrite slab bounded by LHMs media is investigated and discussed
SOIL EROSION BY TILLAGE IN RAINFED N-W. EGYPTION COAST
Tillage erosion is one of the main causes of land degradation. The objective of the present study is to evaluate the effect of tillage systems (up and downslope and contour tillage), soil conditions (consolidated and loosened soils), tillage depth, speed and slope on tillage erosion rate. Field experiments of variable slopes (3 - 16%) were established on sandy soil of Wadi El Ramala, west Mersa Matruh City. Soil translocation as affected by tillage systems and soil conditions were examined. In addition, soil losses by tillage erosion and water erosion were measured and evaluated.
The experimental results showed that the average displacement distance is a function of gradient slopes, soil condition, tillage system, depth and speed. The validation of the soil translocation model developed by (Van Muysen et al 2000), under different gradient slopes, tillage depth, speed and soil condition were evaluated. This validation showed that variations in tracer displacement distance can be successfully predicted. Consequently, such model can be used under sandy soil. Finally, experiment results showed that tillage operations with a chisel plow under present agricultural practices are responsible for the major field redistribution of soil. Furthermore, it is clear that tillage of a loosened soil is far more erosive than tillage of a consolidated soil, where the tillage transport coefficient (K) was 105 kg.m-1 per tillage operation for consolidated soil and 179 kg.m-1 for loosened soil under contour tillage. However, 256 kg.m-1 per tillage prevailed for consolidated soil and 454 kg.m-1 for loosened soil under up and downslope tillage treatments
Survival and quality of life in incident systemic sclerosis-related pulmonary arterial hypertension
Background: Pulmonary arterial hypertension (PAH) is a leading cause of mortality in systemic sclerosis (SSc). We sought to determine survival, predictors of mortality, and health-related quality of life (HRQoL) related to PAH in a large SSc cohort with PAH. Methods: We studied consecutive SSc patients with newly diagnosed (incident) World Health Organization (WHO) Group 1 PAH enrolled in a prospective cohort between 2009 and 2015. Survival methods were used to determine age and sex-adjusted standardised mortality ratio (SMR) and years of life lost (YLL), and to identify predictors of mortality. HRQoL was measured using the Short form 36 (SF-36) instrument. Results: Among 132 SSc-PAH patients (112 female (85%); mean age 62 ± 11 years), 60 (45.5%) died, with a median (±IQR) survival time from PAH diagnosis of 4.0 (2.2-6.2) years. Median (±IQR) follow up from study enrolment was 3.8 (1.6-5.8) years. The SMR for patients with SSc-PAH was 5.8 (95% CI 4.3-7.8), with YLL of 15.2 years (95% CI 12.3-18.1). Combination PAH therapy had a survival advantage (p < 0.001) compared with monotherapy, as did anticoagulation compared with no anticoagulation (p < 0.003). Furthermore, combination PAH therapy together with anticoagulation had a survival benefit compared with monotherapy with or without anticoagulation and combination therapy without anticoagulation (hazard ratio 0.28, 95% CI 0.1-0.7). Older age at PAH diagnosis (p = 0.03), mild co-existent interstitial lung disease (ILD) (p = 0.01), worse WHO functional class (p = 0.03) and higher mean pulmonary arterial pressure at PAH diagnosis (p = 0.001), and digital ulcers (p = 0.01) were independent predictors of mortality. Conclusions: Despite the significant benefits conferred by advanced PAH therapies suggested in this study, the median survival in SSc PAH remains short at only 4 years.Kathleen Morrisroe, Wendy Stevens, Molla Huq, David Prior, Jo Sahhar, Gene-Siew Ngian, David Celermajer, Jane Zochling, Susanna Proudman, Mandana NikpourEmail author and the Australian Scleroderma Interest Group (ASIG
ELECTRONIC VISION AND USES IN AUTOMATIC HANDLING OF AGRICULTURAL MATERIALS
Sorting machines of fruits are mostly used in the industries. The process of sorting started by detecting the color of the fruits to indicate its classification based on the color of the fruit. In this work, a fruit sorting machine has been designed and built for small scale industries needing low cost compared to those now being used, which are expensive. This quest focuses on sorting the different types of fruits such as apples, tomatoes, and navel orange which are green and red. The fruits are put on a small belt and then entered through a box with a controlled lighting Red- Green- Blue color sensor. The controlled lighting is in a closed space with a servo motor which rotates 130 degree and returns to zero position. Attached to it, a gate pushes the fruit to the line of correct color and RGB color sensor to make scanning, integrated with Red and non-Red (Green) Light Emitting Diode (RGB LED), to detect the color of the fruit. Study also includes productivity, efficiency and costs were determined.  Results revealed the following - The productivity is arranged from low to high as follows: tomatoes (27.3: 61.2 kg/h), apples (34.1: 76.5 kg/h), and navel orange (68.1: 153 kg/h). - The efficiency of sorting was as follows: tomatoes was 96 % at the lowest belt speed and increased to 100 % at the mean belt speed 0.8 m/s then decreased to 94 % at the highest speed, apples was 95 % at the lowest belt speed and increased to 100 % at the mean belt speed 0.8 m/s then decreased to 91.25 % at the highest speed, and navel orange was 95 % at the lowest belt speed and increased to 100 % at the mean belt speed 0.8 m/s then decreased to 80 % at the highest speed. - The most suitable belt speed was 0.8 m/s with very small delay time of servo motor which gives the highest efficiency of sorting within free flowing conditions. The sorting process cost by using the developed machine was less than the manual process in case of navel orange, tomatoes and apples. Using the developed sorting machine reduced the cost of fruits sorting to 1: 2.23 as compared with manual method in navel orange, and to 1 : 1.12 for apples, but it was more expensive sorting tomatoes by the developed machine compared with manual sorting of 12%
The association of low complement with disease activity in systemic sclerosis: a prospective cohort study
Background: In some rheumatic diseases such as systemic lupus erythematosus (SLE), low serum complement ('hypocomplementaemia') is a feature of active disease. However, the role of hypocomplementaemia in systemic sclerosis (SSc) is unknown. We sought to determine the frequency, clinical associations and relationship to disease activity of hypocomplementaemia in SSc. Methods: The study included 1140 patients fulfilling the 2013 American College of Rheumatology criteria for SSc. Demographic, serological and clinical data, obtained prospectively through annual review, were analysed using univariable methods. Linear and logistic regression, together with generalised estimating equations, were used to determine the independent correlates of hypocomplementaemia ever, and at each visit, respectively. Results: At least one episode of hypocomplementaemia (low C3 and/or low C4) occurred in 24.1 % of patients over 1893 visits; these patients were more likely to be seropositive for anti-ribonucleoprotein (OR = 3.8, p = 0.002), anti-Ro (OR = 2.2, p = 0.002), anti-Smith (OR = 6.3, p = 0.035) and anti-phospholipid antibodies (OR = 1.4, p = 0.021) and were more likely to display features of overlap connective tissue disease, in particular polymyositis (OR = 16.0, p = 0.012). However, no association was found between hypocomplementaemia and either the European Scleroderma Study Group disease activity score or any of its component variables (including erythrocyte sedimentation rate) in univariate analysis. Among patients with SSc overlap disease features, those who were hypocomplementaemic were more likely to have digital ulcers (OR = 1.6, p = 0.034), tendon friction rubs (OR = 2.4, p = 0.037), forced vital capacity <80 % predicted (OR = 2.9, p = 0.008) and lower body mass index (BMI) (OR for BMI = 0.9, p < 0.0005) at that visit, all of which are features associated with SSc disease activity and/or severity. Conclusions: While hypocomplementaemia is not associated with disease activity in patients with non-overlap SSc, it is associated with some features of increased SSc disease activity in patients with overlap disease features.James Esposito, Zoe Brown, Wendy Stevens, Joanne Sahhar, Candice Rabusa, Jane Zochling, Janet Roddy, Jennifer Walker, Susanna M. Proudman, and Mandana Nikpo
Epidemiology and disease characteristics of systemic sclerosis-related pulmonary arterial hypertension: results from a real-life screening programme
Pulmonary arterial hypertension (PAH) is the leading cause of death in systemic sclerosis (SSc). Annual screening with echocardiogram (ECHO) is recommended. We present the methodological aspects of a PAH screening programme in a large Australian SSc cohort, the epidemiology of SSc-PAH in this cohort, and an evaluation of factors influencing physician adherence to PAH screening guidelines.Patient characteristics and results of PAH screening were determined in all patients enrolled in a SSc longitudinal cohort study. Adherence to PAH screening guidelines was assessed by a survey of Australian rheumatologists. Summary statistics, chi-square tests, univariate and multivariable logistic regression were used to determine the associations of risk factors with PAH.Among 1636 patients with SSc, 194 (11.9%) had PAH proven by right-heart catheter. Of these, 160 were detected by screening. The annual incidence of PAH was 1.4%. Patients with PAH diagnosed on subsequent screens, compared with patients in whom PAH was diagnosed on first screen, were more likely to have diffuse SSc (p = 0.03), be in a better World Health Organisation (WHO) Functional Class at PAH diagnosis (p = 0.01) and have less advanced PAH evidenced by higher mean six-minute walk distance (p = 0.03), lower mean pulmonary arterial pressure (p = 0.009), lower mean pulmonary vascular resistance (p = 0.006) and fewer non-trivial pericardial effusions (p = 0.03). Adherence to annual PAH screening using an ECHO-based algorithm was poor among Australian rheumatologists, with less than half screening their patients with SSc of more than ten years disease duration.PAH is a common complication of SSc. Physician adherence to PAH screening recommendations remains poor. Identifying modifiable barriers to screening may improve adherence and ultimately patient outcomes.Kathleen Morrisroe, Wendy Stevens, Joanne Sahhar, Candice Rabusa, Mandana Nikpour, Susanna Proudman and the Australian Scleroderma Interest Group (ASIG
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