Dual-mode compact structure comprising of side-fed bifilar and quadrifilar helix antenna

A side-fed bifilar helix antenna can be integrated with a quadrifilar helix antenna in a piggy back configuration in order to achieve a dual-mode radiating structure. The overall length of the structure is 0.44 lambda at the resonant frequency (1.54 GHz) of the space mode antenna and 0.39 lambda at the resonant frequency (1.34 GHz) of the terrestrial mode antenna. The computed results are validated by experimental data.

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.

Acoustic features of song categories and their possible implications for communication in the common nightingale (Luscinia megarhynchos)

In many passerine species, males sing more than one distinct song type. Commonly, songs are assigned to different song types or song categories based on phonological and syntactical dissimilarities. However, temporal aspects, such as song length and song rate, also need to be considered to understand the possible functions of different songs. Common nightingales (Luscinia megarhynchos) have large vocal repertoires of different song types but their songs additionally can be grouped into two distinct categories (particular groups of song types): whistle songs and nonwhistle songs. Whistle songs are hypothesised to be important to attract migrating females. We studied temporal properties of whistle songs and nonwhistle songs and examined the relationship between those song parameters and song output parameters, such as song rate and song length. To investigate how song parameters vary among males, we calculated the coefficients of variation for different song traits. We found that the variation in the proportion of whistle songs was significantly higher among males than variation in other song parameters. Furthermore, the proportion of whistle songs was negatively correlated with other sona output patterns. These findings suggest that the production of whistle songs might be constrained and/or that whistle songs and their succeeding pauses may act as a functional unit in communication.

The rotational broadening of V395 Carinae. Implications on the compact object's mass

Context: The masses previously obtained for the X-ray binary 2S 0921-630 inferred a compact object that was either a high-mass neutron star or low-mass black-hole, but used a previously published value for the rotational broadening (v sin i) with large uncertainties. Aims: We aim to determine an accurate mass for the compact object through an improved measurement of the secondary star's projected equatorial rotational velocity. Methods: We have used UVES echelle spectroscopy to determine the v sin i of the secondary star (V395 Car) in the low-mass X-ray binary 2S 0921-630 by comparison to an artificially broadened spectral-type template star. In addition, we have also measured v sin i from a single high signal-to-noise ratio absorption line profile calculated using the method of Least-Squares Deconvolution (LSD). Results: We determine v sin i to lie between 31.3±0.5 km s-1 to 34.7±0.5 km s-1 (assuming zero and continuum limb darkening, respectively) in disagreement with previous results based on intermediate resolution spectroscopy obtained with the 3.6 m NTT. Using our revised v sin i value in combination with the secondary star's radial velocity gives a binary mass ratio of 0.281±0.034. Furthermore, assuming a binary inclination angle of 75° gives a compact object mass of 1.37±0.13 M_?. Conclusions: We find that using relatively low-resolution spectroscopy can result in systemic uncertainties in the measured v sin i values obtained using standard methods. We suggest the use of LSD as a secondary, reliable check of the results as LSD allows one to directly discern the shape of the absorption line profile. In the light of the new v sin i measurement, we have revised down the compact object's mass, such that it is now compatible with a canonical neutron star mass.

Compact ridge waveguide filter with parallel and series-coupled resonators

A novel 3rd-order compact E-plane ridge waveguide filter is presented. Miniaturization is achieved upon introducing a configuration of parallel-coupled E-plane ridge waveguide resonators. Furthermore, the proposed filter allows for transmission zeros at finite frequencies. Fabrication simplicity and mass producibility of standard E-plane filters is maintained. The numerical and experimental results are presented to validate the proposed configuration. A miniaturisation factor of 2 and very sharp upper cutoff are achieved. 2005 Wiley Periodicals, Inc.

Compact ridged-waveguide bandpass filters and diplexers

A ridged-waveguide diplexer incorporating integrated compact ridged-waveguide filters and a ridged-waveguide T-junction is presented. The compact size of the filter is achieved by integrating of bandpass periodic filter, and a low-pass structure is used in order to suppress spurious responses. Simulation using the mode-matching method has been carried out for ridge-waveguide filters and T junctions and the results are presented. The measured results are in good agreement with the simulated results. (C) 2004 Wiley Periodicals, Inc.

Compact Toffoli gate using weighted graph states

We introduce three compact graph states that can be used to perform a measurement-based Toffoli gate. Given a weighted graph of six, seven, or eight qubits, we show that success probabilities of 1/4, 1/2, and 1, respectively, can be achieved. Our study puts a measurement-based version of this important quantum logic gate within the reach of current experiments. As the graphs are setup independent, they could be realized in a variety of systems, including linear optics and ion traps.

Disaggregating conservative Protestant groups in Northern Ireland: Overlapping categories and the importance of a born-again self-identification

Rather than treating conservative Protestantism as a homogenous phenomenon, recent literature has underlined the importance of disaggregating this group to illuminate important attitudinal and behavioral differences between conservative Protestants. However, the methods used to empirically operationalize conservative Protestantism have not always been able to capture variations within the groupings. Based on analysis of the 2004 Northern Ireland Life and Times Survey, we argue that religious self-identification is a more useful way of analyzing conservative Protestant subgroups than denomination or religious belief. We show that many of these identifications are overlapping, rather than stand-alone, religious group identifications. Moreover, the identification category of born-again has seldom been included in surveys. We find having a born-again identification to be a better predictor than the more frequently asked fundamentalist and evangelical categories of the religious and social beliefs that are seen as indicative of conservative Protestantism.

Beyond Compliance – Below Expectations? Cross-Border CSR, Development and the UN Global Compact.

In this paper, the results of an empirical analysis of a set of 416 descriptive case studies published by corporate members of the UN Global Compact are presented. Although these cases cannot be viewed as representative of the Compact itself or of corporate social responsibility (CSR) and development in general, they can illustrate which kinds of projects are deemed appropriate as best practice examples among Compact members, and therefore indicate the direction, in which predominantly voluntary and business-led CSR might at best be evolving. To help contextualize the analysis, the paper starts with a brief overview of recent academic work on the strengths and limitations of CSR in the light of international development, followed by the empirical analysis of Compact case studies. The results raise doubts regarding the general suitability of contemporary CSR initiatives to tackle some of the most pressing developmental challenges. Instead, only certain topics are commonly addressed, while a number of issues such as anti-corruption measures or labour rights are underrepresented in the case study sample. Regarding the target regions of the best practice examples, the majority is reported on activities based in OECD countries and a small number of emerging markets such as South Africa, India or China, while neglecting other regions such as sub-Saharan Africa (excluding South Africa). From a European Union policy perspective, these results indicate that there is a role to play for the state in order to create a better fit between CSR agendas and the actual developmental needs in the South.

Pattern Switching Compact Patch Antenna for On-body and Off-body Communications at 2.45 GHz

The ability to switch between propagating modes is important for body-centric applications such as medical body area networks where a single node may need to be able to optimise communications for either on-body sensor links or off-body links to the wider network. Therefore, we present a compact 2.45 GHz active mode-switching wearable antenna for both on-body and off-body wireless communications. The single-layer patch antenna was pattern-switched using shorting pins and had an impedance bandwidth of 253 MHz and 217 MHz for the on-body and off-body radiating modes, respectively. An efficiency of 57 % and 56.8 % was obtained for on-body and off-body mode respectively when placed in close proximity to a phantom that represents a muscle issue at 2.45 GHz.