High gain flexible liquid crystal polymer based 8‐element printed antenna for millimetric wave applications

In this article, an offset fed printed dipole antenna 2‐element, 4‐element, and 8‐element arrays are developed and analyzed for millimeter wave applications. The 8‐element array antenna is of compact size with dimensions 43.6 × 25.1 × 0.25 mm³. It achieved a broad impedance bandwidth (S₁₁ < ?10 dB) of 15.7 GHz from 24.7 to 40.4 GHz. The mutual coupling between array elements is less than ?35 dB in the operating band. The antenna achieved a gain of 12.62 to 13.1 dB. The 8‐element array antenna is fabricated on liquid crystal polymer material and tested. Impedance matching, far field radiation characteristics, co‐polarized and cross‐polarized patterns and group delay are analyzed in simulation and experimental measurement. The investigated results are in good agreement and hence, the developed array antenna is attractive for wideband millimeter wave applications.     

Neural networks and statistical techniques: A review of applications

Neural networks are being used in areas of prediction and classification, the areas where statistical methods have traditionally been used. Both the traditional statistical methods and neural networks are looked upon as competing model-building techniques in literature. This paper carries out a comprehensive review of articles that involve a comparative study of feed forward neural networks and statistical techniques used for prediction and classification problems in various areas of applications. Tabular presentations highlighting the important features of these articles are also provided. This study aims to give useful insight into the capabilities of neural networks and statistical methods used in different kinds of applications.     

Spinning of a liquid film from a rotating disc in the presence of a magnetic field — a numerical solution

Summary A numerical solution is obtained for the development of a conducting fluid film on the surface of a spinning disc, in the presence of a magnetic field applied perpendicular to the disc. A finite-difference method is employed to obtain the solution of Navier-Stokes equations modified to include magnetic forces due to MHD interactions. The combined effects of film inertia, acceleration of the disc and magnetic forces are analysed. The numerical results reveal that the rate of thinning of the fluid film is strongly influenced by the inertial and magnetic forces when the Reynolds number is large and that the existing asymptotic theory by Ray and Dandapat [24] is inadequate for predicting transient film thickness. When the disc has a finite acceleration at the start-up, the magnetic and inertia effects are important even at low Reynolds numbers and the thinning rate is reduced. It is observed that for both low and high Reynolds number flows, the film thickness increases with Hartmann numberM for a fixed time and the rate of depletion is less for largeM than for smallM.     

A simple approach for protein structure discrimination based on the network pattern of conserved hydrophobic residues

Evolutionarily conserved hydrophobic residues at the core of protein structures are generally assumed to play a structural role in protein folding and stability. Recent studies have implicated that their importance to protein structures is uneven, with a few of them being crucial and the rest of them being secondary. In this work, we explored the possibility of employing this feature of native structures for discriminating non-native structures from native ones. First, we developed a network tool to quantitatively measure the structural contributions of individual amino acid residues. We systematically applied this method to diverse fold-type sets of native proteins. It was confirmed that this method could grasp the essential structural features of native proteins. Next, we applied it to a number of decoy sets of proteins. The results indicate that such an approach indeed identified non-native structures in most test cases. This finding should be of help for the investigation of the fundamental problem of protein structure prediction.     

Chemiresistive vapor sensing with microscale films of gold monolayer protected clusters

Here we report the stability, conductivity, and vapor-sensing properties of microcontact-printed films of 1.6-nm average diameter hexanethiolate-coated gold monolayer protected clusters (C6 Au MPCs). The C6 Au MPCs were stamped into parallel lines (approximately 1.2 microm wide and 400 nm thick) across two Au electrodes separated by a 1-microm gap. The chemiresistive vapor-sensing properties were measured for saturated toluene and 2-propanol vapors. As-prepared patterned Au MPC films were unstable in the presence of saturated toluene vapor, and their current response was irreversible. Chemically linking the films with vapor-phase hexanedithiol greatly improves their stability and leads to reversible responses. The extent of Au MPC cross-linking and vapor response to organic vapors varies with different exposure times to dithiol vapor. The response to toluene changed from 61 to 8% for exposures of 1 and 60 min, respectively, which is likely due to greater film flexibility with less dithiol exposure. The current measured through the films varies from 10(-11) to 10(-3) Angstroms as a function of the temperature between 250 and 320 degrees C, which correlates with the loss of organic material as measured by FT-IR spectroscopy and the change in thickness and width of the film as measured by atomic force microscopy. The vapor-sensing properties vary with temperature, current, and organic content in the film, which are all interrelated. Response to toluene decreased with increasing temperature and conductivity, while the response to 2-propanol was less predictable. Reducing the size of vapor-sensing devices based on Au MPCs is important for creating highly portable devices that can simultaneously detect multiple analytes. This work demonstrates a simple method for reducing the size of such devices down to the microscale and describes methods for maximizing response, stability, and reversibility.     

Tracing the history of nuclear releases: determination of 129I in tree rings

Concentrations of the long-lived radioisotope 1291 were measured in dated tree rings in order to determine whether the distribution of this isotope reflects the history of nuclear deposition. 129I concentrations and 129I/127I ratios were analyzed in tree rings and bark samples from four trees at West Valley, NY, and from one tree at Rochester, NY. West Valley was the site of short-lived nuclear fuel reprocessing activities (1966-1972), while Rochester, located 115 km to the northeast, provided a regional control site for the study. The selected trees reflect different modes of fluid and nutrient transport in trees, with three species of ring-porous trees (elm, oak, and locust), one semidiffuse (cherry), and one diffuse-porous tree (maple). The results show that 1291 levels in ring-porous trees, in which xylem or hydrologic tissue is localized in the outermost growth ring, are generally well correlated with the expected 1291 deposition pattern for the region. In contrast, tree rings of the more common semidiffuse to diffuse-porous wood, where xylem is disseminated throughout the trunk, show a less well developed 129I signal, probably due to the transport of iodine ions across annual rings. Iodine concentrations in the tree rings range from 0.04 to 2 mg/kg, 129I/127I ratios from 6 x 10(-10) to 3.8 x 10(-6). Tree bark and the outermost rings show significantly higher 129I concentrations than the wood of the trunk. The 129I/127I ratios for bark are very similar to values obtained for surface soil and water at the two localities, while inner rings have ratios similar to those in deeper layers of the soil, reflecting different pathways for 129I uptake and the differences in ambient 1291 levels between the atmosphere and deep soil. Although ring porous trees preserve the depositional pattern of nuclear releases, rings older than or close to the onset of the nuclear age have 129I/127I ratios significantly above the preanthropogenic level, suggesting that even in these trees some redistribution of 129I occurs throughout the trunk. Our results indicate that growth rings from ring-porous wood are useful in time-series analyses of regional 129I deposition, yielding reliable information on relative changes in 129I concentrations but requiring caution in the reconstruction of absolute ambient concentrations during any given time.     

17O NMR and crystalline hydrates

A physiopathological role for acetylcholine (ACh) was hypothesized during ageing and related neurodegenerative diseases, e.g. dementia. This research was aimed to study acetylcholinesterase (AChE) activity during development and ageing of the frontal cerebral cortex of 4-, 8-, 12-, 16-, 20- and 24-month-old rats. This study was performed on synaptic plasma membranes, the specific subcellular compartment where the enzyme is located in vivo both in control animals and after in vivo acute treatment with L-acetylcarnitine. Maximum AChE activity was unaffected by age, and L-acetylcarnitine treatment increased enzyme activity in synaptic plasma membranes of 8-month-old rats. A comprehensive analysis of these results suggests: (a) the observed alterations in protein can substantially affect neurochemical data if results are presented as specific activities per unit protein; (b) energy metabolism plays the major role in the disturbed ACh metabolism during ageing and (c) the understanding of the mode of action of L-acetylcarnitine in treatment of dementia.     

A computer simulation of solar radiation

Various algebraic formulas for representing solar radiation data are discussed and the results obtained are compared.     

Reliability evaluation of a communication system considering a multistate model

The methods most often suggested for reliability evaluation of communication systems/flow networks consider two states, namely the good state and the bad state. This paper considers multistate modelling of the network elements. The states which permit a flow less than the maximum assigned capacity are assumed as parallel and mutually exclusive elements in the network. A method is proposed for reliability evaluation of a communication network considering multistate modelling of the network elements. The proposed method has been implemented on a computer and results obtained using the proposed method are compared with the existing methods for the two state model conditions.     

A passive-heated building for a cool,humid climate in India

This paper describes the design and thermal performance of a passive-heated building for the cool, humid climatic conditions of Srinagar, India. The annual climatic variations of Srinagar are from a cold and very humid winter to a temperate, humid late summer. Thus, the major trend is creating comfort conditions by appropriate heating. The design discussed here therefore uses passive heating concepts. Special care is taken to prevent wasteful heat losses during the winter and unwanted heat gains in the summer. In order to ascertain the performance of the design, a thermal analysis has been carried out. The performance was found to be satisfactory.