Cone penetration testing in polar snow

Innovative Cone Penetration Testing (CPT) using adapted commercial CPT equipment was conducted in Antarctica in early 2010 in an attempt to assess the strength of polar snow; additionally, application of CPT data was considered, particularly in estimating surface bearing capacity. Almost 100 CPT tests were carried out and both qualitative and quantitative analysis of data was undertaken. Additional supporting testing in- cluded snow density assessment, snow strength assessment, extrapolation of CPT data via Ground Penetrating Radar (GPR) and preliminary mini-cone penetrometer testing in Greenland. Analysis of results revealed that assessing the strength of polar snow via CPT is affected by numerous factors including penetration rate, cone size/shape and snow material properties, particularly compaction of the snow undergoing penetration. A density-dependant relationship between CPT resistance and snow shear strength was established, and methods for estimating surface bearing capacity directly from CPT in homogeneous and layered polar snow were proposed. This work applied existing technology in a new material and shows that CPT can be used efficiently in polar environs to provide estimates of snow shear strength and surface bearing capacity, to depths of 10 m or more

A Property Law Reader: Cases, Questions and Commentary, 4th Edition, Preface and Table of Contents

Property law — that body of rules which describes and defines relationships between people with respect to things — involves many choices. The choices include determining when it is appropriate and desirable to label something as property or, more accurately, as subject to a relationship between people based in the rules of property law. The choices involve asking questions, including why it is that we create relationships based in property and who should benefit from them. The rules of property law are notoriously difficult and complex, and they frequently appear disjointed and unconnected, but they are not arbitrary. They are based on choices, sometimes made explicitly, other times implicitly, about what is important. One of our principal goals in this collection of property law materials is to emphasize that the making of choices is a necessary, although commonly under-acknowledged, element in creating a regime of property law. We have made a choice to highlight what Margaret Davies has described as ‘‘asking the why question”. This involves using materials that prompt not only an investigation of the rules of property law but also the justifications for those rules. Another choice we have made in compiling this material is to highlight the disparate sources of property law. Excerpts from the decisions of common law courts dominate the page count, and learning to derive the principles and the rules from these decisions is a core element in a common law legal education, but there is much else besides. We have chosen to emphasize Indigenous legal traditions as one of the sources of Canadian property law alongside the civil law tradition in Quebec and the common law tradition (including principles of equity) in the rest of the country. This presents challenges, not the least because the concept or category of property, as it has developed in western legal traditions, sits uneasily with many Indigenous legal traditions. But it is also a useful reminder that the rules governing human relationships with respect to things are not only jurisdictionally, but also culturally and historically specific. The law of property is also to be found in a great diversity of legislative instruments, ranging from city by-laws, through provincial and federal statutes and regulations, to international agreements. These sources are scattered throughout the volume, but using them presents other challenges. Within the Canadian federation, property is primarily a matter of provincial jurisdiction, and the diversity of property regimes among the provinces limits our capacity to delve into the particular statutory framework of any one jurisdiction when producing a set of materials that is relevant across Canadian common law jurisdictions. As a result, we include examples from different jurisdictions and leave it to course instructors to add as much or as little of what is particular to their jurisdictions as they think desirable

Surface-driven electronic structure in LaFeAsO studied by angle resolved photoemission spectroscopy

We measured the electronic structure of an iron arsenic parent compound LaFeAsO using angle resolved photoemission spectroscopy (ARPES). By comparing with a full-potential Linear Augmented PlaneWave calculation we show that the extra large Gamma hole pocket measured via ARPES comes from electronic structure at the sample surface. Based on this we discuss the strong polarization dependence of the band structure and a temperature-dependent hole-like band around the M point. The two phenomena give additional evidences for the existence of the surface-driven electronic structure.Comment: 6 pages, 6 figure

A Study of Obscuration in Catadioptric Lenses

In this paper we will examine the effect of obscuration upon the various features we desired to image with a 157nm microstepper utilising a catadioptric lens. We will show the effect the obscuration has upon imaging when using not only conventional illumination and binary masks, but also when using a range of enhancement techniques such as off-axis illumination and phase-shifting masks. We will show how use of a large obscuration, whilst enhancing the signals for the densest features, actually degrades the signal for more isolated features. The level of obscuration must also take into account cross duty-ratio effects, i.e. the distribution of diffraction energy, for phase shifted features of various sizes. In this situation where a small sigma would be used a large level of obscuration can significantly increase biases. The choice of obscuration can have a major effect upon the imaging capabilities of a tool. In future, when the use of catadioptric lenses may be more widespread (for example this may happen at 157nm) it may be desirable to have the option to vary this obscuration dependant upon the pattern being imaged

Nitric oxide activates ATP-sensitive potassium channels in mammalian sensory neurons: action by direct S-nitrosylation

<p>Abstract</p> <p>Background</p> <p>ATP-sensitive potassium (K_ATP) channels in neurons regulate excitability, neurotransmitter release and mediate protection from cell-death. Furthermore, activation of K_ATPchannels is suppressed in DRG neurons after painful-like nerve injury. NO-dependent mechanisms modulate both K_ATPchannels and participate in the pathophysiology and pharmacology of neuropathic pain. Therefore, we investigated NO modulation of K_ATPchannels in control and axotomized DRG neurons.</p> <p>Results</p> <p>Cell-attached and cell-free recordings of K_ATPcurrents in large DRG neurons from control rats (sham surgery, SS) revealed activation of K_ATPchannels by NO exogenously released by the NO donor SNAP, through decreased sensitivity to [ATP]i.</p> <p>This NO-induced K_ATPchannel activation was not altered in ganglia from animals that demonstrated sustained hyperalgesia-type response to nociceptive stimulation following spinal nerve ligation. However, baseline opening of K_ATPchannels and their activation induced by metabolic inhibition was suppressed by axotomy. Failure to block the NO-mediated amplification of K_ATPcurrents with specific inhibitors of sGC and PKG indicated that the classical sGC/cGMP/PKG signaling pathway was not involved in the activation by SNAP. NO-induced activation of K_ATPchannels remained intact in cell-free patches, was reversed by DTT, a thiol-reducing agent, and prevented by NEM, a thiol-alkylating agent. Other findings indicated that the mechanisms by which NO activates K_ATPchannels involve direct S-nitrosylation of cysteine residues in the SUR1 subunit. Specifically, current through recombinant wild-type SUR1/Kir6.2 channels expressed in COS7 cells was activated by NO, but channels formed only from truncated isoform Kir6.2 subunits without SUR1 subunits were insensitive to NO. Further, mutagenesis of SUR1 indicated that NO-induced K_ATPchannel activation involves interaction of NO with residues in the NBD1 of the SUR1 subunit.</p> <p>Conclusion</p> <p>NO activates K_ATPchannels in large DRG neurons via direct S-nitrosylation of cysteine residues in the SUR1 subunit. The capacity of NO to activate K_ATPchannels via this mechanism remains intact even after spinal nerve ligation, thus providing opportunities for selective pharmacological enhancement of K_ATPcurrent even after decrease of this current by painful-like nerve injury.</p