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We describe the design and performance of the Engineering Development Array, which is a low-frequency radio telescope comprising 256 dual-polarisation dipole antennas working as a phased array. The Engineering Development Array was conceived of, developed, and deployed in just 18 months via re-use of Square Kilometre Array precursor technology and expertise, specifically from the Murchison Widefield Array radio telescope. Using drift scans and a model for the sky brightness temperature at low frequencies, we have derived the Engineering Development Array’s receiver temperature as a function of frequency. The Engineering Development Array is shown to be sky-noise limited over most of the frequency range measured between 60 and 240 MHz. By using the Engineering Development Array in interferometric mode with the Murchison Widefield Array, we used calibrated visibilities to measure the absolute sensitivity of the array. The measured array sensitivity matches very well with a model based on the array layout and measured receiver temperature. The results demonstrate the practicality and feasibility of using Murchison Widefield Array-style precursor technology for Square Kilometre Array-scale stations. The modular architecture of the Engineering Development Array allows upgrades to the array to be rolled out in a staged approach. Future improvements to the Engineering Development Array include replacing the second stage beamformer with a fully digital system, and to transition to using RF-over-fibre for the signal output from first stage beamformers.
Glyphosate is used in the transition zone to control annual bluegrass in fully dormant warm-season grasses. A suspected resistant (R) biotype of annual bluegrass was identified on a golf course in South Carolina after at least 10 consecutive years of glyphosate application. Greenhouse bioassays revealed the R biotype was 4.4-fold resistant to glyphosate compared with a standard susceptible (S) biotype. Further studies were conducted to investigate the mechanism conferring glyphosate resistance in the R biotype. Leaf discs of both biotypes accumulated shikimate in response to increasing glyphosate concentration, but the glyphosate concentration resulting in 50% EPSP synthase inhibition as a result of shikimate accumulation (I50) was 4.2-fold higher in the R biotype compared with the S biotype. At the whole plant level, similar levels of shikimate accumulation were observed between biotypes at 6 and 24 h after treatment (HAT) with glyphosate, but greater shikimate accumulation occurred in the S biotype at 72, 120, and 168 HAT. Shikimate levels decreased in the R biotype after 72 HAT. There were no differences in 14C-glyphosate absorption between biotypes. However, more 14C-glyphosate translocated out of the treated leaf in the R biotype and into root tissues over time compared with the S biotype. Partial sequencing of the EPSP synthase gene revealed a point mutation that resulted in an Ala substitution at Pro106. Although other mechanisms may contribute to glyphosate resistance, these results confirm a Pro106 to Ala substitution is associated with resistance to glyphosate in the R annual bluegrass biotype.
Energy-dispersive X-ray spectrometry (EDS) is an analytical technique used to determine elemental composition. It is a powerful, easy-to-use, non-destructive technique that can be employed for a wide variety of materials. In this technique the electron beam of the scanning electron microscope (SEM) impinges on the sample and excites atomic electrons causing the production of characteristic X rays. These characteristic X rays have energies specific to elements in the sample. The EDS detector collects these X rays as a signal and produces a spectrum. Samples also can be excited by X rays. Collimated and focused X rays from an X-ray source produce characteristic X rays that can be detected by the same EDS detector. When X rays are used as the source of excitation, the method is then called X-ray fluorescence (XRF) or micro-XRF.
Migration has been an integral part of human activity for as long as people have inhabited the earth. Whether moving as individuals, families or tribes, migration is an age-old response to the physical need for food, shelter and security, and the psychological need for adventure and exploration. However, while migration has marked all periods of human history, the phenomenon of ‘international migration’ had to await the reordering of the geopolitical landscape as a collection of territorial States in which governments had authority over settled populations residing within defined geographic boundaries.
The Treaty of Westphalia (1648) was a critical turning point in establishing that new landscape, but for the next two centuries individuals still enjoyed substantial freedom in traversing the boundaries of the State. This reflected an attitude of hospitality to strangers that was inherited from ancient cultures and expressed through cosmopolitanism. This attitude can be seen in the scholarly works of the great writers of international law of the eighteenth and nineteenth centuries, who, with few exceptions, took a liberal attitude to the movement of people across borders for trade, commerce and other purposes. If law in this early period paid scant attention to regulating migration, it was partly for the practical reason that the number of people involved was modest because modes of transport were confined to land crossings by foot or horse, and sea crossings by wind-powered sailing vessels. There were some notable exceptions to this laissez-faire approach, but the circumstances in which law was invoked to regulate international migration were few.
International migration law is an important field of international law, which has attracted exceptional interest in recent years. This book has been written from a wide variety of perspectives for those wanting to understand the legal framework that regulates migration. It is intended for students new to this field of study who seek an overview of its many components. It will also appeal to those who have focussed on a particular branch of international migration law but require an understanding of how their specialisation fits with other branches of the discipline. Written by migration law specialists and led by respected international experts, this volume draws upon the combined knowledge of international migration law and policy from academia; international, intergovernmental, regional and non-governmental organisations; and national governments. Additional features include case studies, maps, break-out boxes and references to resources which allow for a full understanding of the law in context.
International migration has been a topic on the lips of policy makers for a very long time. The policy interests of States vary widely. Some seek to promote immigration to meet local labour shortages, or facilitate emigration to generate a stream of remittances and foster local development. Others take a more cautious approach because of concerns about irregular migration or national security, or because their societies historically have not welcomed foreigners. These different policy stances are reflected in a vast and complex array of national migration laws that span issues of nationality, entry, exit, deportation, detention, visa classes, status determination, migration-related crime and access to social services. These laws are generally well known within States because they are applied on a daily basis by immigration officials, consular officers, border patrols and crime investigators.
By contrast, the framework of international law governing migration is fragmented and unfamiliar. While some pockets are well recognised – refugee law being the principal example – many dimensions of the international legal framework remain unknown to all but a small coterie of specialists. Many individuals who formulate national migration laws, policies and practices, or are required to implement them, are thus unaware of the rich lode of international agreements, customary law, resolutions, recommendations and guidelines informing developments at the national level.