Measurement of a biomimetic antenna in the shape of a bat's ear

This paper presents a series of measurements of a novel antenna that physically resembles the ear of a bat. The antenna consists of a circular ground plane with a central monopole element. An equilateral triangular conducting plate is curved around the ground so that the base of the triangle is electrically connected to the perimeter of the circle and is of the same length. The input characteristic is reminiscent of a simple monopole above a circular ground, providing there are a sufficient number of modes in the triangular plate at the frequency of interest. In contrast to the plain monopole, certain frequencies yield a high gain and a radiation pattern with low side lobes. Measurements presented in this paper suggest that the antenna performance is broadly comparable with its acoustic analogue, although there are differences between the acoustic and electromagnetic implementation which have yet to be resolved

A New Halocarbon Absorption Model Based on HITRAN Cross-Section Data and New Estimates of Halocarbon Instantaneous Clear-Sky Radiative Forcing

The article describes a new practical model for the infrared absorption of chlorofluorocarbons and other gases with dense spectra, based on high-resolution transmission molecular absorption database (HITRAN) absorption cross-sections. The model is very simple, consisting of frequency-dependent polynomial coefficients describing the pressure and temperature dependence of absorption. Currently it is implemented for the halocarbon species required by the Radiative Forcing Model Intercomparison Project. In cases where cross-section data is available at a range of different temperatures and pressures, this approach offers practical advantages compared to previously available options, and is traceable, since the polynomial coefficients follow directly from the laboratory spectra. The new model is freely available and has several important applications, notably in remote sensing and in developing advanced radiation schemes for global circulation models that include halocarbon absorption. For demonstration, the model is applied to the problem of computing instantaneous clear-sky halocarbon radiative efficiencies and present day radiative forcing. Results are in reasonable agreement with earlier assessments that were carried out with the less explicit Pinnock method, and thus broadly validate that method. Plain Language Summary Chlorofluorocarbons and other related gases have dense and complicated absorption spectra that can be measured in the laboratory. We bring such measurements to a form that can be used for simulations of the transfer of radiation through the atmosphere. Then we use the new model to calculate new estimates of the climate impact of these man-made gases. The results broadly validate earlier calculations that were done with a less explicit method

Magnetic ordering of Mn sublattice, dense Kondo lattice behavior of Ce in (RPd3)8Mn (R = La, Ce)

We have synthesized two new interstitial compounds (RPd3)8Mn (R = La and Ce). The Mn ions present in "dilute" concentration of just 3 molar percent form a sublattice with an unusually large Mn-Mn near neighbor distance of ~ 85 nm. While the existence of (RPd3)8M (where M is a p-block element) is already documented in the literature, the present work reports for the first time the formation of this phase with M being a 3d element. In (LaPd3)8Mn, the Mn sub-lattice orders antiferromagnetically as inferred from the peaks in low-field magnetization at 48 K and 23 K. The latter peak progressively shifts towards lower temperatures in increasing magnetic field and disappears below 1.8 K in a field of ~ 8 kOe. On the other hand in (CePd3)8Mn the Mn sublattice undergoes a ferromagnetic transition around 35 K. The Ce ions form a dense Kondo-lattice and are in a paramagnetic state at least down to 1.5 K. A strongly correlated electronic ground state arising from Kondo effect is inferred from the large extrapolated value of C/T = 275 mJ/Ce-mol K^2 at T = 0 K. In contrast, the interstitial alloys RPd3Mnx (x = 0.03 and 0.06), also synthesized for the first time, have a spin glass ground state due to the random distribution of the Mn ions over the available "1b" sites in the parent RPd3 crystal lattice.Comment: 18 figures and 20 pages of text documen

Discrimination, labour markets and the Labour Market Prospects of Older Workers: What Can a Legal Case Teach us?

As governments become increasingly concerned about the fiscal implications of the ageing population, labour market policies have sought to encourage mature workers to remain in the labour force. The ‘human capital’ discourses motivating these policies rest on the assumption that older workers armed with motivation and vocational skills will be able to return to fulfilling work. This paper uses the post-redundancy recruitment experiences of former Ansett Airlines flight attendants to develop a critique of these expectations. It suggests that policies to increase older workers’ labour market participation will not succeed while persistent socially constructed age- and gender- typing shape labour demand. The conclusion argues for policies sensitive to the institutional structures that shape employer preferences, the competitive rationality of discriminatory practices, and the irresolvable tension between workers’ human rights and employers’ property rights

Companion animals are spillover hosts of the Multidrug-resistant human extraintestinal escherichia coli pandemic Clones ST131 and ST1193

Escherichia coli sequence types 131 (ST131) and 1193 are multidrug-resistant extraintestinal pathogens that have recently spread epidemically among humans and are occasionally isolated from companion animals. This study characterized a nationwide collection of fluoroquinolone-resistant (FQR) E. coli isolates from extraintestinal infections in Australian cats and dogs. For this, 59 cat and dog FQR clinical E. coli isolates (representing 6.9% of an 855-isolate collection) underwent PCR-based phylotyping and whole-genome sequencing (WGS). Isolates from commensal-associated phylogenetic groups A (14/59, 24%) and B1 (18/59, 31%) were dominant, with ST224 (10/59, 17%), and ST744 (8/59, 14%) predominating. Less prevalent were phylogenetic groups D (12/59, 20%), with ST38 (8/59, 14%) predominating, and virulence-associated phylogenetic group B2 (7/59, 12%), with ST131 predominating (6/7, 86%) and no ST1193 isolates identified. In a WGS-based comparison of 20 cat and dog-source ST131 isolates with 188 reference human and animal ST131 isolates, the cat and dog-source isolates were phylogenetically diverse. Although cat and dog-source ST131 isolates exhibited some minor sub-clustering, most were closely related to human-source ST131 strains. Furthermore, the prevalence of ST131 as a cause of FQR infections in Australian companion animals was relatively constant between this study and the 5-year-earlier study of Platell et al. (2010) (9/125 isolates, 7.2%). Thus, although the high degree of clonal commonality among FQR clinical isolates from humans vs. companion animals suggests the possibility of bi-directional between-species transmission, the much higher reported prevalence of ST131 and ST1193 among FQR clinical isolates from humans as compared to companion animals suggests that companion animals are spillover hosts rather than being a primary reservoir for these lineages

Quantum coherence in a degenerate two-level atomic ensemble: for a transition Fe=0↔Fg=1F_e=0\leftrightarrow F_g=1

For a transition $F_e=0\leftrightarrow F_g=1$ driven by a linearly polarized light and probed by a circularly light, quantum coherence effects are investigated. Due to the coherence between the drive Rabi frequency and Zeeman splitting, electromagnetically induced transparency, electromagnetically induced absorption, and the transition from positive to negative dispersion are obtained, as well as the populations coherently oscillating in a wide spectral region. At the zero pump-probe detuning, the subluminal and superluminal light propagation is predicted. Finally, coherent population trapping states are not highly sensitive to the refraction and absorption in such ensemble.Comment: 9 pages, 6 figure

First Principles Calculations of Fe on GaAs (100)

We have calculated from first principles the electronic structure of 0.5 monolayer upto 5 monolayer thick Fe layers on top of a GaAs (100) surface. We find the Fe magnetic moment to be determined by the Fe-As distance. As segregates to the top of the Fe film, whereas Ga most likely is found within the Fe film. Moreover, we find an asymmetric in-plane contraction of our unit-cell along with an expansion perpendicular to the surface. We predict the number of Fe 3d-holes to increase with increasing Fe thickness on $p$-doped GaAs.Comment: 9 pages, 14 figures, submitted to PR

The extent, nature and distribution of child poverty in India

Despite a long history, research on poverty has only relatively recently examined the issue of child poverty as a distinct topic of concern. This article examines how child poverty and well-being are now conceptualized, defined and measured, and presents a portrait of child poverty in India by social and cultural groups, and by geographic area. In December 2006, the UN General Assembly adopted a definition of child poverty which noted that children living in poverty were deprived of (among other things) nutrition, water and sanitation facilities, access to basic health care services, shelter and education. The definition noted that while poverty hurts every human being ‘it is most threatening and harmful to children, leaving them unable to enjoy their rights, to reach their full potential and to participate as full members of the society’. Researchers have developed age-specific and gender-sensitive indicators of deprivation which conform to the UN definition of child poverty and which can be used to examine the extent and nature of child poverty in low and middle-income countries. These new methods have ‘transformed the way UNICEF and many of its partners both understood and measured the poverty suffered by children’ (UNICEF, 2009). This article uses these methods and presents results of child poverty in India based on nationally representative household survey data for India

Auger decay of degenerate and Bose-condensed excitons in Cu2_2O

We study the non-radiative Auger decay of excitons in Cu$_2$O, in which two excitons scatter to an excited electron and hole. The exciton decay rate for the direct and the phonon-assisted processes is calculated from first principles; incorporating the band structure of the material leads to a relatively shorter lifetime of the triplet state ortho excitons. We compare our results with the Auger decay rate extracted from data on highly degenerate triplet excitons and Bose-condensed singlet excitons in Cu$_2$O.Comment: 15 pages, revtex, figures available from G. Kavoulaki

Multiple field inflation

Inflation offers a simple model for very early evolution of our Universe and the origin of primordial perturbations on large scales. Over the last 25 years we have become familiar with the predictions of single-field models, but inflation with more than one light scalar field can alter preconceptions about the inflationary dynamics and our predictions for the primordial perturbations. I will discuss how future observational data could distinguish between inflation driven by one field, or many fields. As an example, I briefly review the curvaton as an alternative to the inflaton scenario for the origin of structure.Comment: 27 pages, no figures. To appear in proceedings of 22nd IAP Colloquium, Inflation +25, Paris, June 200