Multiscale models of angiogenesis

This article aims to promote integration of angiogenesis-related models, both integration of the work described herein and many other existing and future models. Integration of molecular mechanisms with cell- and organ- level models allows investigators to study angiogenesis from perspectives in time and space that were once unattainable. As new tools develop for the systematic validation, integration, visualization, and adaptation of these models, the field of angiogenesis heralds an era where modeling becomes an essential component of rigorous experimental design and therapeutic advances.     

Energy consideration for designing supercharged ram jet engines

The present work investigates the energy considerations and performance characteristics of a newly proposed supercharged ram jet engine. Thermodynamics and fluid mechanics analyses were developed to predict specific thrust, thrust‐specific fuel consumption (TSFC), overall efficiency, and thrust‐to‐weight ratio of the engine. Compressor pressure ratio and efficiency, combustor temperature, and pressure losses in the burner and nozzle are considered as primary variables in the engine performance analysis. Performance characteristics are calculated to illustrate the effect of each parameter independently at different flight speeds. This is done while maintaining other parameters at given typical operating values. A computer program was developed to perform the iterative calculations. Results indicate that the compressor pressure ratio and the combustion product temperature are the most critical parameters in determining the performance of the engine. At compressor pressure ratio of 1.15–1.2, the typical static thrust‐to‐weight ratio is at maximum. Increasing combustion product temperature increases the thrust‐to‐weight ratio as well as TSFC. Finally, newly developed high power‐to‐weight ratio IC engine makes it possible for the supercharged ram jet engine to achieve high performance, in terms of thrust‐to‐weight ratio and TSFC. Copyright © 2007 John Wiley & Sons, Ltd.     

The corrosion behavior of TiN coated and uncoated incoloy 800 alloy

Incoloy alloy 800 is used in a variety of applications in industry as well as in domestic appliances for sheeting on electric heating elements. The composition of the alloy enables it to resist deterioration in many corrosive environments. However, resistance of the alloy to corrosion in aqueous media needs to be further examined. The present study examines the corrosion properties of Incoloy 800 alloy of both coated and uncoated workpieces obtained in a 0.1N H₂SO₄ + 0.05N NaCl solution. TiN coating is achieved using a physical vapor deposition (PVD) technique while corrosion tests are carried out using electrochemical polarization methods. Moreover, in order to examine the influence of hydrogen diffusion, reduction of hydrogen at the Incoloy 800 surface is carried out in a solution of 0.1N HNO₃ + 1 g/L thiourea. Tensile tests are conducted on the workpieces to determine the influence of hydrogen embrittlement on the resulting mechanical properties of the substrate. To examine the pit formation and stress induced microcracking, scanning electron microscope (SEM) analysis is carried out. The results show that the corrosion resistance of the alloy improves after TiN coating. In addition, no specific pattern or differentiation on the pit geometry is observed. The pitting rate and its size reduce considerably for TiN coated workpieces.     

The costs of urbanization: a case study of Pakistan

"A methodology is developed for estimating the aggregate costs of urbanization in Pakistan for 1983-2003. These costs are then compared with the future investment resource pool, and are found to be larger than the total pool. Alternative policy solutions to alleviate the problem are explored. Although some capital-saving strategies (such as major public works programs in rural areas and labor-intensive employment policies) would be helpful, it will be impossible to avoid a substantial rise in the proportion of the urban population without services from about one quarter to about one half of the total. The paper concludes with suggestions for refining the methodology in future studies."     

Clinical profile of patients admitted to the coronary care unit with possible myocardial infarction without diagnostic ECG and/or enzyme changes

Concern has been expressed about the cost-effectiveness of the Coronary Care Unit (CCU) and solution options offered on account of the large number of patients admitted to the CCU who turn out not to have acute myocardial infarction. In a prospective study over four years, we studied a group of patients admitted to the CCU with suspected myocardial infarction but who did not have diagnostic ECG and/or enzyme changes for the causes of their chest pain. We compared the clinical profile of these patients (Group A) with that of a random sample of patients with confirmed myocardial infarction (Group B). Gastrointestinal disorders, musculoskeletal chest pain, panic and anxiety disorders were the major causes of chest pain in Group A patients. A normal ECG and a normal creatine phosphokinase (CPK) within the first 24 hours, a normal initial random blood sugar, a younger age and absence of coronary risk factors effectively separated Group A patients as low risk from Group B patients as high risk for acute myocardial infarction. These simple parameters will assist physicians providing CCU care in most hospitals in early decision making and in the judicious use of the CCU.     

An epistemic event‐based correlation approach for managing pervasive networks

Existing pervasive applications are based on time series data that possess the form of time‐ordered series of events. Such applications also embody the need to handle large volumes of unexpected events, often modified on‐the‐fly, containing conflicting information, and dealing with rapidly changing contexts while producing results with low latency. Correlating events across contextual dimensions holds the key to expanding the capabilities and improving the performance of these applications. In this paper we analyze complex‐event semantic correlation that examines epistemic uncertainty in computer networks by using Dempster–Shafer theory to support a high‐volume, event‐based, in‐network and non‐deterministic pervasive network management. We consider imprecision and uncertainty when an event is detected and associate a belief parameter with the semantics and the detection of composite events. The approach taps into in‐network processing capabilities of pervasive computer networks and can withstand missing or conflicting information gathered from multiple participating entities. In the end, we establish that a lightweight, distributed, large‐volume, event‐based technique which exploits epistemic uncertainty to correlate events along contextual dimensions provides a successful technique for enabling management of large‐scale and pervasive contemporary and future computer networks. Copyright © 2011 John Wiley & Sons, Ltd.     

Deletions of single extracellular loops affect pH sensitivity, but not voltage dependence, of the Escherichia coli porin OmpF

The molecular basis for the voltage and pH dependence of the Escherichia coli OmpF porin activity remains unknown. The L3 loop was previously shown not be involved in voltage dependence. Here we used seven OmpF mutants where single extracellular loops, except L3, were deleted one at a time. The proteins are expressed at levels comparable to wild-type and purified as trimers. Wild-type and mutant proteins were inserted into planar lipid bilayers for electrophysiological measurement of their activity. Current-voltage relationships show the typical porin channel closure at voltages greater than the critical voltage. Measurements of critical voltages for the seven deletion mutants showed no significant differences relative to wild-type, hence eliminating the role of single loops in voltage sensitivity. However, deletions of loops L1, L7 or L8 affected the tendency of channels to close at acidic pH. Wild-type channels close more readily at acidic pH and their open probability is decreased by approximately 60% at pH 4.0 relative to pH 7.0. For mutants lacking loop L1, L7 or L8, the channel open probability was found not to be significantly different at pH 4.0 than at pH 7.0. The other deletion mutants retained a pH sensitivity similar to the wild-type channel. Possible mechanistic scenarios for the voltage- and pH dependence of E.coli OmpF porin are discussed based on these results.     

Belief based data cleaning for wireless sensor networks

Wireless sensor network (WSN) data is often subjected to corruption and losses due to wireless medium of communication and presence of hardware inaccuracies in the nodes. For a WSN application to deduce an appropriate result it is necessary that the data received is clean, accurate, and lossless. WSN data cleaning systems exploit contextual associations existing in the received data to suppress data inconsistencies and anomalies. In this work we attempt to clean the data gathered from WSN by capturing the influence of changing dynamics of the environment on the contextual associations existing in the sensor nodes. Specifically, our work validates the extent of similarities among the sensed observations from contextually (spatio‐temporally) associated nodes and considers the time of arrival of data at the sink to educate the cleaning process about the WSN's behavior. We term the data cleaning technique proposed in this work as time of arrival for data cleaning (TOAD). TOAD establishes belief on spatially related nodes to identify potential nodes that can contribute to data cleaning. By using information theory concepts and experiments on data sets from a real‐time scenario we demonstrate and establish that validation of contextual associations among the sensor nodes significantly contributes to data cleaning. Copyright © 2010 John Wiley & Sons, Ltd.