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Why is CDMA the solution for mobile satellite communication

It is demonstrated that spread spectrum Code Division Multiple Access (CDMA) systems provide an economically superior solution to satellite mobile communications by increasing the system maximum capacity with respect to single channel per carrier Frequency Division Multiple Access (FDMA) systems. Following the comparative analysis of CDMA and FDMA systems, the design of a model that was developed to test the feasibility of the approach and the performance of a spread spectrum system in a mobile environment. Results of extensive computer simulations as well as laboratory and field tests results are presented

Technical characteristics of the OmniTRACS: The first operation mobile Ku-band satellite communications system

The techinical characteristics of the OmniTRACS system are described. The system is the first operational mobile Ku-band satellite communications system and provides two-way message and position determination service to mobile terminals using existing Ku-band satellites. Interference to and from the system is minimized by the use of special spread-spectrum techniques, together with low power and low data rate transmissions

A second anniversary operational review of the OmniTRACS(R): The first two-way mobile Ku-band satellite communications system

A novel two-way mobile satellite communications and vehicle position reporting system that is currently operational in the United States and Europe is described. The system characteristics and service operations are described in detail. Technical descriptions of the equipment and signal processing techniques are provided

Optimal control of 3D state constrained induction heating problems with nonlocal radiation effects

The paper is concerned with a class of optimal heating problems in semiconductor single crystal growth processes. To model the heating process, time-harmonic Maxwell equations are considered in the system of the state. Due to the high temperatures characterizing crystal growth, it is necessary to include nonlocal radiation boundary conditions and a temperature-dependent heat conductivity in the description of the heat transfer process. The first goal of this paper is to prove the existence and uniqueness of the solution to the state equation. The regularity analysis associated with the time harmonic Maxwell equations is also studied. In the second part of the paper, the existence and uniqueness of the solution to the corresponding linearized equation is shown. With this result at hand, the differentiability of the control-to-state mapping operator associated with the state equation is derived. Finally, based on the theoretical results, first oder necessary optimality conditions for an associated optimal control problem are established

Optimal control of 3D state-constrained induction heating problems with nonlocal radiation effects

The paper is concerned with a class of optimal heating problems in semiconductor single crystal growth processes. To model the heating process, time-harmonic Maxwell equations are considered in the system of the state. Due to the high temperatures characterizing crystal growth, it is necessary to include nonlocal radiation boundary conditions and a temperature-dependent heat conductivity in the description of the heat transfer process. The first goal of this paper is to prove the existence and uniqueness of the solution to the state equation. The regularity analysis associated with the time harmonic Maxwell equations is also studied. In the second part of the paper, the existence and uniqueness of the solution to the corresponding linearized equation is shown. With this result at hand, the differentiability of the control-to-state mapping operator associated with the state equation is derived. Finally, based on the theoretical results, first oder necessary optimality conditions for an associated optimal control problem are established

Revising Pediatric Vancomycin Dosing Accounting for Nephrotoxicity in a Pharmacokinetic-Pharmacodynamic Model

This study aimed to suggest an initial pediatric vancomycin dose regimen through population pharmacokinetic-pharmacodynamic modeling. A population pharmacokinetic approach was used to analyze vancomycin concentration-time data from a large pediatric cohort. Pharmacokinetic target attainment for patients with bloodstream isolates was compared with clinical outcome using logistic regression and classification and regression trees. Change in serum creatinine during treatment was used as an indicator of acute nephrotoxicity. Probability of acute kidney injury (50% increase from baseline) or kidney failure (75% increase from baseline) was evaluated using logistic regression. An initial dosing regimen was derived, personalized by age, weight, and serum creatinine, using stochastic simulations. Data from 785 hospitalized pediatric patients (1 day to 21 years of age) with suspected Gram-positive infections were collected. Estimated (relative standard error) typical clearance, volume of distribution 1, intercompartmental clearance, and volume of distribution 2 were (standardized to 70 kg) 4.84 (2.38) liters/h, 39.9 (8.15) liters, 3.85 (17.3) liters/h, and 37.8 (10.2) liters, respectively. While cumulative vancomycin exposure correlated positively with the development of nephrotoxicity (713 patients), no clear relationship between vancomycin area under the plasma concentration-time curve and efficacy was found (102 patients). Predicted probability of acute kidney injury and kidney failure with the optimized dosing regimen at day 5 was 10 to 15% and 5 to 10%, increasing by approximately 50% on day 7 and roughly 100% on day 10 across all age groups. This study presents the first data-driven pediatric dose selection to date accounting for nephrotoxicity, and it indicates that cumulative vancomycin exposure best describes risk of acute kidney injury and acute kidney failure

Useful knowledge, 'industrial enlightenment', and the place of India

Research is now turning to the missing place of technology and ‘useful knowledge’ in the debate on the ‘great divergence’ between East and West. Parallel research in the history of science has sought the global dimensions of European knowledge. Joel Mokyr's recent The Enlightened Economy (2009) argued the place of an exceptional ‘industrial enlightenment’ in Europe in explaining industrialization there, but neglected the wide geographic framework of European investigation of the arts and manufactures. This article presents two case studies of European industrial travellers who accessed and described Indian crafts and industries at the time of Britain's industrial revolution and Europe's Enlightenment discourse on crafts and manufactures. The efforts of Anton Hove and Benjamin Heyne to ‘codify’ the ‘tacit’ knowledge of a part of the world distant from Europe were hindered by the English East India Company and the British state. Their accounts, only published much later, provide insight into European perceptions of India's ‘useful knowledge’

Perceived Stress, Thinking Style and Paranormal Belief

Paranormal beliefs often become stronger in times of stress. Such beliefs have also been found to vary in accordance with thinking style, whereby stronger beliefs are often observed in experiential thinkers. Little research, however, has explored the interaction between perceived stress and thinking style. 82 males and females aged 18 to 62 years (mean = 29.96 ± 12.53 years) completed measures of perceived stress, thinking style (rational and experiential) and paranormal belief. The results revealed stronger beliefs in experiential thinkers, compared with those with a rational thinking style. Perceived stress alone, was not a prominent predictor of belief but the combination of stress and thinking style, specifically high perceived stress with a rational thinking style, significantly predicted greater global paranormal belief, belief in superstition, traditional religious belief, and belief in psi. High perceived stress appeared to facilitate belief in rational thinkers as conversely, belief was lowest in rational thinkers under conditions of low-perceived stress. These findings suggest that stress may lower the propensity for rational thinking and consequently, encourage belief in scientifically unsubstantiated phenomena. This interaction may have implications for coping during stressful situations