Compact quadrifilar helix antenna

Introduction: The quadrifilar helix antenna (QHA) is used widely for terrestrial [1] and space communication systems [2], where it is necessary to generate a circularly polarised cardioid-shaped radiation pattern with a high front-to-back ratio and low cross-polarisation. The radiating structure comprises four helical conductors which are excited in phase quadrature at the feed point, which is usually located at the centre of the top radials. The physical size of the quadrifilar antenna can be reduced by dielectric loading [3] or by meandering the printed linear elements [4]. However, in the former arrangement dielectric absorption reduces the radiation efficiency of the antenna, and the latter technique is not suitable for constructing free standing wire structures, which are normally used for spacecraft payloads in the VHF and UHF bands [2]. This Letter shows that a significant reduction in the axial length of a 1/2 turn half-wavelength QHA can be achieved by modifying the geometry of the helices in the region around the midpoint where a current null exists. Simulated and experimental results at L band are used to show that a size reduction of up to 15% is possible without significantly degrading the pattern shape and the bandwidth.

Neuroactive substances and associated major muscle systems in Bucephaloides gracilescens (Trematoda : Digenea) metacercaria and adult

Cholinergic, serotoninergic and neuropeptidergic components of the nervous system were examined and compared in the progenetic metacercaria and adult gasterostome trematode, Bucephaloides gracilescens in order to provide baseline information on neuronal control of the musculature involved in egg-assembly. Enzyme cytochemistry and indirect immunocytochemical techniques interfaced with confocal scanning laser microscopy demonstrated all three classes of neuroactive substance throughout the central and peripheral nervous systems. A comparable orthogonal arrangement of the central nervous system (CNS) and peripheral array of nerve plexuses was observed in both metacercaria and adult. Staining patterns for cholinergic and peptidergic substances showed significant overlap, while the serotoninergic system was confined to a separate set of neurons. Immunostaining for FMRFamide-related peptides (FaRPs) was strong in the CNS and peripheral innervation to the attachment apparatus of metacercaria and adult but was only found in the innervation of the ootype in ovigerous adults, implicating FaRPs in neuronal control of the muscle of the female reproductive tract during egg-assembly.

Organization of the musculature of schistosome cercariae

Phalloidin-fluorescein isothiocyanate staining of filamentous actin was used to identify muscle systems within the cercariae of Schistosoma mansoni. Examination of labeled cercariae by confocal scanning laser microscopy revealed distinct organizational levels of myofiber arrangements within the body wall, anterior cone, acetabulum, and esophagus. The body wall throughout showed a typical latticelike arrangement of outer circular and inner longitudinal myofibers, with an additional innermost layer of diagonal fibers in the anterior portion of the body. Circular and longitudinal fibers were also evident in the anterior organ and esophagus and. to some extent, the ventral acetabulum. Most striking was the striation of the cercarial tail musculature.

Molecular systematics of Ceramium and Centroceras (Ceramiaceae, Rhodophyta) from Brazil

Morphological investigations identified 11 Ceramium Roth species, of the 18 previously reported from Brazil. Phylogenetic analyses of sequences of the chloroplast-encoded rbcL gene confirmed the presence of seven of these species. Three other species are reported from Brazil for the first time. Ceramium affine Setchell & Gardner and C. filicula Harvey ex Womersley were previously known only from the Pacific Ocean (Mexico and Australia, respectively). A new species, C. fujianum Barros-Barreto et Maggs sp. nov., is described here. Its general habit is similar to that of C. strictum sensu Harvey from Europe but it has one less periaxial cell than C. strictum; its cortical filament arrangement is closest to C. deslongchampsii Chauvin ex Duby, also from Europe, but whorled tetrasporangia partially covered by cortical cells differ strikingly from the naked protruding tetrasporangia of C. deslongchampsii. Ceramium species in which each periaxial cell cuts off transversely only a single basipetal cell formed a robust clade. The genus Ceramium as represented in Brazil is not monophyletic with respect to Centroceras Kutzing and Corallophila Weber-van Bosse; Ceramium nitens, which has axial cells completely covered by rounded cortical cells formed by acropetal and basipetal filaments, did not group with any Ceramium clade but was weakly allied to a species of Corallophila. All three Brazilian Centroceras sequences were attributed to a single species, C. clavulatum.

Analysing orchestrations with risk profiles and angel-daemon games

In this paper game theory is used to analyse the effect of a number of service failures during the execution of a grid orchestration. A service failure may be catastrophic in that it causes an entire orchestration to fail. Alternatively, a grid manager may utilise alternative services in the case of failure, allowing an orchestration to recover, A risk profile provides a means of modelling situations in a way that is neither overly optimistic nor overly pessimistic. Risk profiles are analysed using angel and daemon games. A risk profile can be assigned a valuation through an analysis of the structure of its associated Nash equilibria. Some structural properties of valuation functions, that show their validity as a measure for risk, are given. Two main cases are considered, the assessment of Orc expressions and the arrangement of a meeting using reputations.

Imidazolium ionic liquid crystals with pendant mesogenic groups

Ionic liquid crystals were obtained by coupling one or two mesogenic units (cholesterol or cyanobiphenyl) to an imidazolium cation. Anions are bromide, bis(trifluoromethylsulfonyl)imide, and tetrakis(2-thenoyltrifluoroacetonato)europate(III). The mesomorphism of the compounds depends on the type and number of mesogenic units and on the type of anion. In general, the most stable mesophases are observed for the bis(trifluoromethylsulfonyl)imide salts. Most of the compounds containing cholesterol moieties show enantiotropic SmA* phases over a broad temperature range, and some of them are room temperature liquid crystals. Modeling of the small-angle X-ray scattering patterns revealed the molecular arrangement in these mesophases. On the contrary, most of the compounds containing cyanobiphenyl groups exhibit monotropic lamellar or nematic mesophases, depending on the number of mesogenic units. The imidazolium salts containing the tetrakis(2-thenoyltrifluoroacetonato)europate(III) anion show an intense red photoluminescence.

'Leaving Nothing to Chance'?: Joint Tenancies, The 'Right' of Survivorship and Unilateral Severance

The joint tenancy with its inherent right of survivorship is the most prevalent form of co-ownership in the common law world today. Most couples will be joint tenants of a family home, while relations (such as siblings) who purchase property together may opt for this arrangement. Inter vivos acquisitions aside, the huge intergenerational transfer of wealth within families on death can result in a joint tenancy, and it may also be a convenient estate planning device. The fact that property automatically vests in the surviving joint tenants on death is the reason why many people choose this form of co-ownership. However, there is one serious disadvantage. A joint tenancy is an inflexible form of landholding where relationships sour or family circumstances change over time, and co-owners want their respective `shares' of the property to pass to someone else on death. Where consensual severance is not possible, one joint tenant can sever unilaterally. The latter mechanism is vital in terms of giving effect to the wishes of the severing joint tenant, especially in situations of discord or a breakdown in relations with their fellow co-owners. However, unilateral severance also has serious implications for the non-severing joint tenant(s) who expected to inherit property through survivorship, and can impact significantly on ownership of the home and other family property. This article looks at unilateral severance as a means of subverting the right of survivorship. The focus is on personal and inter-family relationships, and the various legal issues and policy considerations associated with unilateral severance across the common law jurisdictions of Britain, Ireland, Australia, Canada, and New Zealand. It assesses the various methods of effecting unilateral severance and proposes specific measures, as well as considering novel arguments for preventing unilateral severance based on contractual agreements to the contrary and proprietary estoppel.

EFFECT OF SURFACE RESISTOR LOADING ON HIGH-IMPEDANCE SURFACE RADAR ABSORBER RETURN LOSS AND BANDWIDTH

A simple method for the selection of the appropriate choice of surface-mounted loading resistor required for a thin radar absorber based on a high-impedance surface (HIS) principle is demonstrated. The absorber consists of a HIS, (artificial magnetic ground plane), thickness 0.03 lambda(0) surface-loaded resistive-elements interconnecting a textured surface of square patches. The properties of absorber are characterized under normal incident using a parallel plate waveguide measurement technique over the operating frequency range of 2.6-3.95 GHz. We show that for this arrangement return loss and bandwidth are insensitive to +/- 2% tolerance variations in surface resistor values about the value predicted using the method elaborated in this letter, and that better than -28 dB at 3.125 GHz reflection loss can be obtained with an effective working bandwidth of up to 11% at -10 dB reflection loss. (C) 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1733-1775, 2009; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/mop.24454

Multiple Evidence for Gold(I)center dot center dot center dot Silver(I) Interactions in Solution

[AuAg3(C6F5)(CF3CO2)(3)(CH2PPh3)](n) (2) was prepared by reaction of [Au(C6F5)(CH2PPh3)] (1) and [Ag(CF3CO2)] (1:3). The crystal structures of complexes I and 2 were determined by X-ray diffraction, and the latter shows a polymeric 2D arrangement built by Au - Ag, Ag - Ag, and Ag - O contacts. The metallophilic interactions observed in 2 in the solid state seem to be preserved in concentrated THF solutions, as suggested by EXAFS, pulsed-gradient spin-echo NMR, and photophysical studies, which showed that the structural motif [AuAg3(C6F5)(CF3CO2)(3)(CH2PPh3)] is maintained under such conditions. Time-dependent DFT calculations agree with the experimental photophysical energies and suggest a metal-to-ligand charge-transfer phosphorescence process. Ab initio calculations give an estimated interaction energy of around 60 kJ mol(-1) for each Au - Ag interaction.

So mechanical or routine: The not original in Feist

The United States Supreme Court case of 1991, Feist Publications, Inc. v. Rural Tel. Service Co., continues to be highly significant for property in data and databases, but remains poorly understood. The approach taken in this article contrasts with previous studies. It focuses upon the “not original” rather than the original. The delineation of the absence of a modicum of creativity in selection, coordination, and arrangement of data as a component of the not original forms a pivotal point in the Supreme Court decision. The author also aims at elucidation rather than critique, using close textual exegesis of the Supreme Court decision. The results of the exegesis are translated into a more formal logical form to enhance clarity and rigor.


The insufficiently creative is initially characterized as “so mechanical or routine.” Mechanical and routine are understood in their ordinary discourse senses, as a conjunction or as connected by AND, and as the central clause. Subsequent clauses amplify the senses of mechanical and routine without disturbing their conjunction.


The delineation of the absence of a modicum of creativity can be correlated with classic conceptions of computability. The insufficiently creative can then be understood as a routine selection, coordination, or arrangement produced by an automatic mechanical procedure or algorithm. An understanding of a modicum of creativity and of copyright law is also indicated.


The value of the exegesis and interpretation is identified as its final simplicity, clarity, comprehensiveness, and potential practical utility.

Effect of corrosion of reinforcement on the mechanical behaviour of highly corroded RC beams

This paper describes an experimental investigation of the behaviour of corroded reinforced concrete beams. These have been stored in a chloride environment for a period of 26 years under service loading so as to be representative of real structural and environmental conditions. The configuration and the widths of the cracks in the two seriously corroded short-span beams were depicted carefully, and then the beams were tested until failure by a three-point loading system. Another two beams of the same age but without corrosion were also tested as control specimens. A short span arrangement was chosen to investigate any effect of a reduction in the area and bond strength of the reinforcement on shear capacity. The relationship of load and deflection was recorded so as to better understand the mechanical behaviour of the corroded beams, together with the slip of the tensile bars. The corrosion maps and the loss of area of the tensile bars were also described after having extracted the corroded bars from the concrete beams. Tensile tests of the main longitudinal bars were also carried out. The residual mechanical behaviour of the beams is discussed in terms of the experimental results and the cracking maps. The results show that the corrosion of the reinforcement in the beams induced by chloride has a very important effect on the mechanical behaviour of the short-span beams, as loss of cross-sectional area and bond strength have a very significant effect on the bending capacity.

Factors influencing eating a varied diet in old age

OBJECTIVE:
To investigate the influences of resources and food-related goals on the variety of food choice among older people.
DESIGN:
A questionnaire-based survey in eight European countries: Poland, Portugal, United Kingdom, Germany, Sweden, Denmark, Italy and Spain.
SUBJECTS:
Participants (n 3200) were above 65 years of age and living in their own homes. The samples were quota samples, eight groups of fifty in each country, based on gender, age and living circumstances, reflecting the diversity of each of the national populations based on education, income and urbanization of living environment.
RESULTS:
Hierarchical multiple regression analysis showed that income, health status, access to a car and living arrangement affected the level of dietary variety. The perceived level of different food-related resources impacted the consumption of a varied diet over and above actual resource levels. Food-related goals contributed to variety of food intake that was not accounted for by the amount of material resources possessed or the social and other resources perceived to be possessed.
CONCLUSIONS:
Older people's variety of food intake depended on material resources (e.g. monthly income, access to a car, living arrangement, physical and mental health). However, in addition to these variables, the way older people perceived other resources, such as their level of appetite, their food knowledge, their perception of the distance to the shops, access to high-quality products, having better kitchen facilities, access to good service providers and support from friends and neighbours, all contributed to how varied a diet they ate.

Morphological Expression of KIT Positive Interstitial Cells of Cajal in Human Bladder

PURPOSE: We investigated the 3-dimensional morphological arrangement of KIT positive interstitial cells of Cajal in the human bladder and explored their structural interactions with neighboring cells.MATERIALS AND METHODS: Human bladder biopsy samples were prepared for immunohistochemistry/confocal or transmission electron microscopy.RESULTS: Whole mount, flat sheet preparations labeled with anti-KIT (Merck, Darmstadt, Germany) contained several immunopositive interstitial cell of Cajal populations. A network of stellate interstitial cells of Cajal in the lamina propria made structural connections with a cholinergic nerve plexus. Vimentin positive cells of several morphologies were present in the lamina propria, presumably including fibroblasts, interstitial cells of Cajal and other cells of mesenchymal origin. Microvessels were abundant in this region and branched, elongated KIT positive interstitial cells of Cajal were found discretely along the vessel axis with each perivascular interstitial cell of Cajal associated with at least 6 vascular smooth muscle cells. Detrusor interstitial cells of Cajal were spindle-shaped, branched cells tracking the smooth muscle bundles, closely associated with smooth muscle cells and vesicular acetylcholine transferase nerves. Rounded, nonbranched KIT positive cells were more numerous in the lamina propria than in the detrusor and were immunopositive for anti-mast cell tryptase. Transmission electron microscopy revealed cells with the ultrastructural characteristics of interstitial cells of Cajal throughout the human bladder wall.CONCLUSIONS: The human bladder contains a network of KIT positive interstitial cells of Cajal in the lamina propria, which make frequent connections with a cholinergic nerve plexus. Novel perivascular interstitial cells of Cajal were discovered close to vascular smooth muscle cells, suggesting interstitial cells of Cajal-vascular coupling in the bladder. KIT positive detrusor interstitial cells of Cajal tracked smooth muscle bundles and were associated with nerves, perhaps showing a functional tri-unit controlling bladder contractility.

Bit error rate performance enhancement of a retrodirective array over a conventional fixed beam array in a dynamic multipath environment

In this paper, we provide experimental evidence to show that enhanced bit error rate (BER) performance is possible using a retrodirective array operating in a dynamically varying multipath environment. The operation of such a system will be compared to that obtained by a conventional nonretrodirective array. The ability of the array to recover amplitude shift keyed encoded data transmitted from a remote location whose position is not known a priori is described. In addition, its ability to retransmit data inserted at the retrodirective array back to a spatially remote beacon location whose position is also not known beforehand is also demonstrated. Comparison with an equivalent conventional fixed beam antenna array utilizing an identical radiating aperture arrangement to that of the retrodirective array are given. These show that the retrodirective array can effectively exploit the presence of time varying multipath in order to give significant reductions in BER over what can be otherwise achieved. Additionally, the retrodirective system is shown to be able to deliver low BER regardless of whether line of sight is present or absent.

RCS CONTROL USING CASCADED CIRCULARLY POLARIZED FREQUENCY SELECTIVE SURFACES AND AN AMC STRUCTURE AS A SWITCHABLE TWIST POLARIZER

This article presents a cascaded arrangement comprising a double-layer frequency selective surface circularly polarizing (CPFSS) and a second screen that can be switched between artificial magnetic conduction (AMC) or perfect electric conducting. (PEC) states. The CPFSS consists of two stacked aluminium sheets patterned with periodic split ring structures While the AMC is a PCB sheet patterned with metallic squares interconnected by links By either open or short circuiting these links it is shown that the cascade of screens can be made to twist, or not to twist, an incident 45 degrees linearly polirized signal through 90 degrees upon reflection from the assembly The system was designed and optimized using CST software and predictions were validated experimentally and measured monostatic reflection loss results (C) 2010 Wiley Periodicals, Inc Microwave Opt Technol Lett 52 577-580, 2010. Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/mop.24979