Tailoring the AMC and EBG characteristics of periodic metallic arrays printed on grounded dielectric substrate

The artificial magnetic conductor (AMC) and electromagnetic band gap (EBG) characteristics of planar periodic metallic arrays printed on grounded dielectric substrate are investigated. The currents induced on the arrays are presented for the first time and their study reveals two distinct resonance phenomena associated with these surfaces. A new technique is presented to tailor the spectral position of the AMC operation and the EBG. Square patch arrays with fixed element size and variable periodicities are employed as working examples to demonstrate the dependence of the spectral AMC and EBG characteristics on array parameters. It is revealed that as the array periodicity is increased, the AMC frequency is increased, while the EBG frequency is reduced. This is shown to occur due to the different nature of the resonance phenomena and the associated underlying physical mechanisms that produce the two effects. The effect of substrate thickness is also investigated. Full wave method of moments (MoM) has been employed for the derivation of the reflection characteristics, the currents and the dispersion relations. A uniplanar array with simultaneous AMC and EBG operation is demonstrated theoretically and experimentally.

FREQUENCY SELECTIVE SURFACE WITH DUAL BAND SWITCHABLE REFLECTION AND TRANSMISSION CHARACTERISTICS

A pin diode-loaded active doubly periodic flat strip FSS is shown to act as a dynamic screen. It is shown that by means of d.c. bias control, we can utilize the screen in, (1) transmission mode as a dual band electromagnetic shutter, or with the inclusion of a ground plane in reflection mode, (is (2) it dual band refection canceller. (3) an amplitude shift keying (ASK) spatial modulator. The properties of the FSS are characterized using a specially designed parallel plate waveguide simulator that permits normal incidence excitation of the FSS under test. (C) 2009 Wiley Periodicals. Inc. Microwave Opt Technol Lett 51: 2059-2061, 2009; Published online in Wiley Inter-Science (www. interscience.wiley.com). DOI 10.1002/mop.24547

Inter- and intrapersonal processes underlying authoritarianism: The role of social conformity and personal need for structure

Several personality constructs have been theorised to underlie right-wing authoritarianism (RWA). In samples from New Zealand and Germany (Ns = 218, 259), we tested whether these constructs can account for specific variance in RWA. In both samples, social conformity and personal need for structure were independent predictors of RWA. In Sample 2, where also openness to experience was measured, social conformity and personal need for structure fully mediated the impact of the higher-order factor of openness on RWA. Our results contribute to the integration of current approaches to the personality basis of authoritarianism. and suggest that two distinct personality processes contribute to RWA: An interpersonal process related to social conformity and an intrapersonal process related to rigid cognitive style. Copyright (C) 2009 John Wiley & Sons, Ltd.

Do environmental and task characteristics matter in the control of externalized local public services? Unveiling the relevance of party characteristics and citizens’ offstage voice

Purpose: The purpose of this paper is to investigate the mechanisms adopted by cities to control the provision of externalized public services and to explore the determinants of such control choices.

Design/methodology/approach: The paper presents the results of a multiple case study based on the experiences of three cities and three public services (transport, solid waste collection and home care services for the elderly), where control mechanisms and their possible antecedents were analyzed.

Findings: The results show that the control models found in the cases analyzed do not correspond to the "pure" patterns described in the private sector literature and that the factors identified by management control contributions do not seem to be exhaustive in explaining the configuration of control systems in the public sector. While environmental and task characteristics only partially explain the adoption of certain configurations of control, the features of the control systems seem to be rather influenced by variables that are related to party characteristics.

Originality/value: The paper shows that the combinations of control mechanisms are more multifaceted than those presented in the literature, and that the factors identified in the private sector literature do not seem to explain comprehensively the configuration of control systems in the public sector. © Emerald Group Publishing Limited.

Investigation on drop penetration and wetting characteristics of powder-liquid systems in relation to the mixing of acrylic bone cement

This study investigated methyl methacrylate – polymethyl methacrylate powder bed interactions through droplet analyses, using model fluids and commercially available bone cement. The effects of storage temperature of liquid monomer and powder packing configuration on drop penetration time were investigated. Methyl methacrylate showed much more rapid imbibition than caprolactone due to decrease in both contact angle and fluid viscosity. Drop penetration of caprolactone through polymethyl methacrylate increased with decrease in bed macro-voids and increase in bulk density as predicted by the modified constant drawing area penetration model and confirmed by drop penetration images. Linear relationships were found between droplet mass and drawing area with imbibition time. Further experiments showed gravimetric analysis of the polymerised methyl methacrylate – polymethyl methacrylate matrix under various storage temperatures correlated with Reynolds number and Washburn analyses. These observations have direct implications for the design of mixing and delivery systems for acrylic bone cements used in orthopaedic surgery.

Clinical and molecular characteristics of hereditary non-polyposis colorectal cancer families in Southeast Asia

Hereditary non-polyposis colorectal cancer (HNPCC), predominantly due to germline MLH1/MSH2 mutations, is the commonest form of hereditary colorectal cancer (CRC), but data in Asians are sparse. We sequenced the MLH1/MSH2 coding and promoter core regions in CRC patients diagnosed below age 40, and/or with multiple primary cancers or familial cancer clustering suggestive of HNPCC, and correlated deleterious mutations with clinical and tumour features. Forty-six Chinese, Malay and Indian kindreds participated. Of the 153 cancers reported in the 46 kindreds, stomach (14%) and urogenital cancers (13%) were the most common extracolonic cancers, whereas endometrial cancer comprised only 7%. Eleven different MLH1 and 12 MSH2 mutations were identified, including nine novel and four recurring mutations in the Chinese. One Indian was a compound heterozygote for an MLH1 and MSH2 mutation. The MLH1/MSH2 mutation data in the Malays and the Indians represents the first in these ethnic groups. Factors strongly associated with deleterious mutations were the Amsterdam criteria, family history of stomach or multiple primary cancers, and MSI-high tumours, whereas family history of endometrial cancer and young cancer age alone correlated poorly. Distinct clinical and molecular characteristics were identified among Asian HNPCC kindreds and may have important clinical implications.

Assessing the conservation status of the freshwater pearl mussel in the North of Ireland - Relevance of growth and age characteristics

In order to conserve the freshwater pearl mussel in Ireland, populations that have a high risk of extinction must he identified and given priority for conservation. Growth of freshwater pearl mussels has been found to vary among populations on a wide geographic scale as well as on a local scale. Populations having a high growth constant (k), because of the small size of individuals and their shorter life-span and thus lower reproductive output, may be more likely to become extinct than those which have a low k and hence larger size and greater reproductive output. This study attempts to estimate the growth constant (k) in rivers in Donegal and Northern Ireland based on measuring lire largest shell in each population. Large differences in values of k were found among rivers and these are discussed in relation to catchment bedrock types and the identification of conservation priorities. Appropriate conservation strategies are recommended for Margaritifera margaritifera populations in the north of Ireland.