Microelectrode arrays and the use of PEG-functionalized diblock copolymer coatings

PEG-modified diblock copolymer surfaces have been examined for their compatibility with microelectrode array based analytical methods. The use of PEG-modified polymer surfaces on the arrays was initially problematic because the redox couples used in the experiments were adsorbed by the polymer. This led the current measured by cyclic voltammetry for the redox couple to be unstable and increase with time. However, two key findings allow the experiments to be successful. First, after multiple cyclic voltammograms the current associated with the redox couple does stabilize so that a good baseline current can be established. Second, the rate at which the current stabilizes is consistent every time a particular coated array is used. Hence, multiple analytical experiments can be conducted on an array coated with a PEG-modified diblock copolymer and the data obtained is comparable as long as the data for each experiment is collected at a consistent time point

Russian gas games or well-oiled conflict? Energy security and the 2014 Ukraine crisis

This essay explores the link between energy security and the 2014 Ukraine crisis. Whenever there is an international conflict involving a major oil or gas producer, commentators are often quick to assume a direct link, and the Ukraine crisis was no exception. Yet, the various avenues through which energy politics have affected the Ukraine crisis, and vice versa, are not well understood. This paper seeks to shed light on the issue by addressing two specific questions. First, how exactly did energy contribute to the crisis in the region? Second, can energy be wielded as a ‘weapon’ by Russia, the EU, or the US? We find that Russian gas pricing played a crucial role as a context factor in igniting the Ukrainian crisis, yet at the same time we guard against ‘energy reductionism’, that is, the fallacy of attributing all events to energy-related issues. We also note that there are strict limits to the so-called energy weapon, whoever employs it. In the conclusion we provide a discussion of the policy implications of these findings

Ab initio study of the CE magnetic phase in half-doped manganites: Purely magnetic versus double exchange description

The leading electronic interactions governing the local physics of the CE phase of half-doped manganites are extracted from correlated ab initio calculations performed on an embedded cluster. The electronic structure of the low-energy states is dominated by double exchange configurations and O-2$p_{\sigma}$ to Mn-3d charge transfer configurations. The model spectra of both a purely magnetic non-symmetric Heisenberg Hamiltonian involving a magnetic oxygen and two non-symmetric double exchange models are compared to the \textit{ab initio} one. While a satisfactory agreement between the Heisenberg spectrum and the calculated one is obtained, the best description is provided by a double exchange model involving excited non-Hund atomic states. This refined model not only perfectly reproduces the spectrum of the embedded cluster in the crystal geometry, but also gives a full description of the local double-well potential energy curve of the ground state (resulting from the interaction of the charge localized electronic configurations) and the local potential energy curves of all excited states ruled by the double exchange mechanism

Caudal cervical vertebral morphological variation is not associated with clinical signs in Warmblood horses

Background Variation in equine caudal cervical spine morphology at C6 and C7 has high prevalence in Warmblood horses and is suspected to be associated with pain in a large mixed-breed group of horses. At present no data exist on the relationship between radiographic phenotype and clinical presentation in Warmblood horses in a case-control study. Objectives To establish the frequency of radiographically visible morphologic variation in a large group of Warmblood horses with clinical signs and compare this with a group without clinical signs. We hypothesised that occurrence of morphologic variation in the case group would not differ from the control group, indicating there is no association between clinical signs and morphologic variation. Study design Retrospective case-control. Methods Radiographic presence or absence of morphologic variation of cervical vertebrae C6 and C7 was recorded in case (n = 245) and control horses (n = 132). Case and control groups were compared by univariable Pearson's Chi-square and multivariable logistic regression for measurement variables age, sex, breed, degenerative joint disease and morphologic variation at C6 and C7. Odds ratio and confidence intervals were obtained. A P <= 0.05 was considered statistically significant. Results Morphologic variation at C6 and C7 (n = 108/377 = 28.6%; Cases 58/245 = 23.7%; Control 50/132 = 38%) was less frequent in horses with clinical signs in univariable testing (OR 0.48, 95% CI 0.3-0.8, P = 0.001). Age, sex, breed and degenerative joint disease were not retained in the final multivariable logistic regression step whereas morphologic variation remained significantly less present in horses with clinical signs. Main limitations Possible demographic differences between equine clinics. Conclusions Morphologic variation in the caudal cervical spine was detected more frequently in horses without clinical signs. Therefore, radiographic presence of such variation does not necessarily implicate the presence of clinical signs

A crude reversal : the political economy of the United States crude oil export policy

Why did the United States (US) lift its forty-year old oil export ban in 2015? Press coverage has offered various answers, such as the decline in crude oil prices and the rise of US tight oil production. Yet, these explanations are incomplete. Prices have declined in the past without a policy change and, in spite of the shale revolution, the US remains a net oil importer. Here, we argue that the repeal of the ban was driven by the confluence of multiple streams in the policy process: a policy problem created by the spread between US and international crude prices, a policy solution advocated by a constituency with growing voice and power, and a window of opportunity offered by falling international oil prices and the budget deal in late 2015. The analysis is a reminder that the policy process behind ostensibly rational energy policies is often less coherent than might be assumed

Near-Field Scanning Microwave Microscopy in the Single Photon Regime

The microwave properties of nano-scale structures are important in a wide variety of applications in quantum technology. Here we describe a low-power cryogenic near-field scanning microwave microscope (NSMM) which maintains nano-scale dielectric contrast down to the single microwave photon regime, up to $10^{9}$ times lower power than in typical NSMMs. We discuss the remaining challenges towards developing nano-scale NSMM for quantum coherent interaction with two-level systems as an enabling tool for the development of quantum technologies in the microwave regime