Tunable beam shaping with a phased array acousto-optic modulator

We demonstrate the generation of Bessel beams using an acousto-optic array based on a liquid filled cavity surrounded by a cylindrical multi-element ultrasound transducer array. Conversion of a Gaussian laser mode into a Bessel beam with tunable order and position is shown. Also higher-order Bessel beams up to the fourth order are successfully generated with experimental results very closely matching simulations

On-site data cast doubts on the hypothesis of shifting cultivation in the Late Neolithic (c. 4300-2400 cal. BC): Landscape management as an alternative paradigm

This article brings together in a comprehensive way, and for the first time, on- and off-site palaeoenvironmental data from the area of the Central European lake dwellings (a UNESCO World Cultural Heritage Site since 2011). The types of data considered are as follows: high-resolution off-site pollen cores, including micro-charcoal counts, and on-site data, including botanical macro- and micro-remains, hand-collected animal bones, remains of microfauna, and data on woodland management (dendrotypology). The period considered is the late Neolithic (c. 4300–2400 cal. BC). For this period, especially for its earlier phases, discussions of land-use patterns are contradictory. Based on off-site data, slash-and-burn – as known from tropical regions – is thought to be the only possible way to cultivate the land. On-site data however show a completely different picture: all indications point to the permanent cultivation of cereals (Triticum spp., Hordeum vulgare), pea (Pisum sativum), flax (Linum usitatissimum) and opium-poppy (Papaver somniferum). Cycles of landscape use are traceable, including coppicing and moving around the landscape with animal herds. Archaeobiological studies further indicate also that hunting and gathering were an important component and that the landscape was manipulated accordingly. Late Neolithic land-use systems also included the use of fire as a tool for opening up the landscape. Here we argue that bringing together all the types of palaeoenvironmental proxies in an integrative way allows us to draw a more comprehensive and reliable picture of the land-use systems in the late Neolithic than had been reconstructed previously largely on the basis of off-site data

Renegotiations of femininity throughout the constitutional debates in Turkey: representative claims in 2014 presidential elections

In August 2014, for the first time in the history of the Turkish Republic, the president was elected through a popular vote. The quest for a new constitution and revisions to the political system were the main topics that the three presidential candidates, Recep Tayyip Erdogan, Ekmeleddin Ihsanoglu and Selahattin Demirtas, raised during their presidential campaigns. Women’s problems and issues were among the central topics through which the matters of the new constitution and the revisions to be made in the system were addressed. Through a qualitative content analysis of the campaign material, this article maps the candidates’ approaches to women’s interests and the roles the candidates promised to play to promote these interests and roles. The findings indicate that motherhood, daughterhood and sisterhood are the key terms through which the candidates formulated the ultimate purpose of their gender-related agenda. They simply blamed the existing constitution as the main cause of alienated motherhood, polarized daughterhood and complicit femininity respectively. Based on the analysis of these simultaneous calls for heightening-disavowal of certain femininities, the article argues that competing projects for the (re)establishment of the constitutional regime in Turkey can be construed as renegotiations of feminine attachments to political authority. © 2017 British Society for Middle Eastern Studie

Prediction of tip-leakage losses in axial turbines

Existing methods for predicting the tip-leakage losses in turbomachinery are based on a variety assumptions, many of which have not been fully verified experimentally. Recently, several detailed experimental studies in turbine cascades have helped to clarify the physics of the flow and provide data on the evolution of the losses. The paper examines the assumptions underlying the prediction methods in the light of these data. An improved model for the losses is developed, using one of the existing models as the starting point

Development of the tip-leakage flow downstream of a planar cascade of turbine blades: Vorticity field

The paper presents detailed measurements of the tip-leakage flow emerging from a planar cascade of turbine blades. Four clearances of from 1.5 to 5.5 percent of the blade chord are considered. Measurements were made at the trailing edge plane, and at two main planes 1.0 and 1.56 axial chord lengths downstream of the cascade. The results give insight into several aspects of the leakage flow, including the size and strength of the leakage vortex in relation to the size of the tip gap and the bound circulation of the blade, and the evolution of the components of vorticity as the vortex diffuses laterally downstream of the blade row. The vortex was found to have largely completed its roll-up into a nearly axisymmetric structure even at the trailing edge of the cascade. As a result, it was found that the vortex could be modeled surprisingly well with a simple model based on the diffusion of a line vortex