A Comparative Study of Nickel Sulphide Deposits Within the Area of the Canadian Shield

In order to plan the future development of the Canadian Shield within a conceptual framework as suggested by the Mid-Canada Corridor concept, both the presently developed and potential, natural resources of this area need to be evaluated for knowledgeable development and management. To this purpose, various areas of nickel sulphide deposits within the area of the Canadian Shield have been studied with the object of determining similar sequences of intrusive events and their spatial relationships. Within the Sudbury area, Ontario, five periods of intrusive activity have been recognized, each period characterized by an initial intrusion of acidic composition, followed in turn by one or more intrusions of basic composition. Genetic relationships among these various intrusives have been noted by the presence of micrographic intergrowths of quartz and feldspar. Increasingly, significant concentrations of nickel sulphides are indicated as having been emplaced at the terminations of the three latest periods. Such features are suggested as being indicative of a process of nickel sulphide concentration and emplacement, namely magmatic differentiation at depth as initially hypothesized by E. Howe (1914) and later modified by A.M. Bateman (1917). A third concept of the Sudbury irruptive is suggested as having consisted of an initial emplacement of micropegmatite, closely followed by a differentiated fraction of norite. The structural shape of the irruptive at depth is suggested by a diagrammatic cross section, suggestive of the descriptive hypothesis of C.W. Knight (1917). Sequences of acidic to basic, intrusive events are also indicated in the areas of Lynn Lake, Manitoba, Moak Lake-Setting Lake, Manitoba, Bird River, Manitoba, Werner Lake-Gordon Lake, Ontario, Shebandowan, Ontario and Marbridge, Malartic, Quebec. The evidence reviewed indicates spatial relationships of nickel sulphide mineralization not only with basic intrusives but also with acidic intrusives and zones of tension fractures

Magnetism in Nb(1-y)Fe(2+y) - composition and magnetic field dependence

We present a systematic study of transport and thermodynamic properties of the Laves phase system Nb$_{1-y}$Fe$_{2+y}$. Our measurements confirm that Fe-rich samples, as well as those rich in Nb (for $\mid y\mid\geq 0.02$), show bulk ferromagnetism at low temperature. For stoichiometric NbFe$_2$, on the other hand, magnetization, magnetic susceptibility and magnetoresistance results point towards spin-density wave (SDW) order, possibly helical, with a small ordering wavevector $Q \sim 0.05$ \AA$^{-1}$. Our results suggest that on approaching the stoichiometric composition from the iron-rich side, ferromagnetism changes into long-wavelength SDW order. In this scenario, $Q$ changes continuously from 0 to small, finite values at a Lifshitz point in the phase diagram, which is located near $y=+0.02$. Further reducing the Fe content suppresses the SDW transition temperature, which extrapolates to zero at $y\approx -0.015$. Around this Fe content magnetic fluctuations dominate the temperature dependence of the resistivity and of the heat capacity which deviate from their conventional Fermi liquid forms, inferring the presence of a quantum critical point. Because the critical point is located between the SDW phase associated with stoichiometric NbFe$_2$ and the ferromagnetic order which reemerges for very Nb-rich NbFe$_2$, the observed temperature dependences could be attributed both to proximity to SDW order or to ferromagnetism.Comment: 13 pages, 20 figure

Action minimizing fronts in general FPU-type chains

We study atomic chains with nonlinear nearest neighbour interactions and prove the existence of fronts (heteroclinic travelling waves with constant asymptotic states). Generalizing recent results of Herrmann and Rademacher we allow for non-convex interaction potentials and find fronts with non-monotone profile. These fronts minimize an action integral and can only exists if the asymptotic states fulfil the macroscopic constraints and if the interaction potential satisfies a geometric graph condition. Finally, we illustrate our findings by numerical simulations.Comment: 19 pages, several figure

Liquid-filled hard gelatin capsules : excipient/capsule compatibility studies

Encapsulation of pharmaceutical formulations as liquids or semisolids, within hard gelatin capsules, presents an important oral dosage strategy for poorly water-soluble drugs, resulting in good bioavailability and reproducible drug absorption. In addition, this technology offers an inherently safer process than powder filled capsules and tablets for highly potent or cytotoxic drugs by avoiding dust generation. Here we present a compatibility study of hard gelatin capsules with common excipients in absence of active pharmaceutical

Diagnostic accuracy of the neurological upper limb examination II: Relation to symptoms of patterns of findings

Background: In a sample of patients in clinical occupational medicine we have demonstrated that an upper limb neurological examination can reliably identify patterns of findings suggesting upper limb focal neuropathies. This further study aimed at approaching the diagnostic accuracy of the examination. Methods: 82 limbs were semi-quantitatively assessed by two blinded examiners ( strength in 14 individual muscles, sensibility in 7 homonymous territories, and mechanosensitivity at 10 locations along nerves). Based on the topography of nerves and their muscular and sensory innervation we defined 10 neurological patterns each suggesting a localized nerve affliction. Information on complaints ( pain, weakness and/or numbness/tingling) collected by others served as a reference for comparison. The relation between the presence of pattern(s) and complaints was assessed by kappa-statistics. Sensitivity, specificity, and positive/negative predictive values were calculated, and pretest odds were compared to post-test probability. Results: The two examiners identified pattern( s) suggesting focal neuropathy in 34/36 out of 38 symptomatic limbs, respectively (kappa = 0.70/0.75), with agreement in 28 limbs. Out of 44 non-symptomatic limbs the examiners agreed on absence of any pattern in 38 limbs. With concordance between the examiners with regard to the presence or absence of any pattern, the sensitivity, specificity, positive and negative predictive values were 0.73, 0.86, 0.93 and 0.90, respectively. While the pre-test odds for a limb to be symptomatic amounted to 0.46 the post-test probability was 0.81. For each examiner the post-test probability was 0.87 and 0.88, respectively. Conclusion: The improved diagnostic confidence is an indication of one aspect of construct validity of the physical examination. For determination of clinical feasibility of the examination further studies are required, most importantly 1) studies of validity by means of comparison with additional references and 2) studies of the potential benefit that can be attained from its use

Improving thermoelectric performance of TiNiSn by mixing MnNiSb in the half-Heusler structure

The thermoelectric properties of n type semiconductor, TiNiSn is optimized by partial substitution with metallic, MnNiSb in the half Heusler structure. Herein, we study the transport properties and intrinsic phase separation in the system. The Ti1-xMnxNiSn1-xSbx alloys were prepared by arc-melting and were annealed at temperatures obtained from differential thermal analysis and differential scanning calorimetry results. The phases were characterized using powder X-ray diffraction patterns, energy dispersive X-ray spectroscopy, and differential scanning calorimetry. After annealing the majority phase was TiNiSn with some Ni rich sites and the minority phases was majorly Ti6Sn5, Sn, and MnSn2. Ni rich sites were caused by Frenkel defects, this led to a metal-like behavior of the semiconducting specimens at low temperature. For x up to 0.05 the samples showed an activated conduction, whereas for x>0.05 they showed metallic character. The figure of merit for x=0.05 was increased by 61% (ZT=0.45) in comparison to the pure TiNiSn.Comment: 7 pages and 5 figures. Submitted to Physical Chemistry Chemical Physics - RSC Publishing on 6th of October, 201

A Search for Hierarchical Triples using Kepler Eclipse Timing

We present the first results of a Kepler survey of 41 eclipsing binaries that we undertook to search for third star companions. Such tertiaries will periodically alter the eclipse timings through light travel time and dynamical effects. We discuss the prevalence of starspots and pulsation among these binaries and how these phenomena influence the eclipse times. There is no evidence of short period companions (P < 700 d) among this sample, but we do find evidence for long term timing variations in 14 targets (34%). We argue that this finding is consistent with the presence of tertiary companions among a significant fraction of the targets, especially if many have orbits measured in decades. This result supports the idea that the formation of close binaries involves the deposition of angular momentum into the orbital motion of a third star.Comment: AJ, in press, 104 pages, 2 figure sets plus 1 regular figur

Quality assurance in stereotactic radiosurgery/radiotherapy according to DIN 6875-1

The new DIN (' Deutsche Industrie- Norm') 6875- 1, which is currently being finalised, deals with quality assurance ( QA) criteria and tests methods for linear accelerator and Gamma Knife stereotactic radiosurgery/ radiotherapy including treatment planning, stereotactic frame and stereotactic imaging and a system test to check the whole chain of uncertainties. Our existing QA program, based on dedicated phantoms and test procedures, has been refined to fulfill the demands of this new DIN. The radiological and mechanical isocentre corresponded within 0.2 mm and the measured 50% isodose lines were in agreement with the calculated ones within less than 0.5 mm. The measured absorbed dose was within 3%. The resultant output factors measured for the 14-, 8- and 4- mm collimator helmet were 0.9870 +/- 0.0086, 0.9578 +/- 0.0057 and 0.8741 +/- 0.0202, respectively. For 170 consecutive tests, the mean geometrical accuracy was 0.48 +/- 0.23 mm. Besides QA phantoms and analysis software developed in- house, the use of commercially available tools facilitated the QA according to the DIN 6875- 1 with which our results complied. Copyright (C) 2004 S. Karger AG, Basel