Prograde garnet growth along complex P-T-t paths: results from numerical experiments on polyphase garnet from the Wölz Complex (Austroalpine basement)

Garnet in metapelites from the Wölz Complex of the Austroalpine crystalline basement east of the Tauern Window characteristically consists of two growth phases, which preserve a comprehensive record of the geothermal history during polymetamorphism. From numerical modelling of garnet formation, detailed information on the pressure-temperature-time (P-T-t) evolution during prograde metamorphism is obtained. In that respect, the combined influences of chemical fractionation associated with garnet growth, modification of the original growth zoning through intragranular diffusion and the nucleation history on the chemical zoning of garnet as P and T change during growth are considered. The concentric chemical zoning observed in garnet and the homogenous rock matrix, which is devoid of chemical segregation, render the simulation of garnet growth through successive equilibrium states reliable. Whereas the first growth phase of garnet was formed at isobaric conditions of ∼3.8kbar at low heating/cooling rates, the second growth phase grew along a Barrovian P-T path marked with a thermal peak of ∼625°C at ∼10kbar and a maximum in P of ∼10.4kbar at ∼610°C. For the heating rate during the growth of the second phase of garnet, average rates faster than 50°CMa−1 are obtained. From geochronological investigations the first growth phase of garnet from the Wölz Complex pertains to the Permian metamorphic event. The second growth phase grew in the course of Eo-Alpine metamorphism during the Cretaceou

Transmyocardial laser revascularisation in acutely ischaemic myocardium

Objective: Although recent experience suggests that transmyocardial laser revascularisation (TMLR) relieves angina, its mechanism of action remains undefined. We examined its functional effects and analysed its morphological features in an animal model of acute ischaemia. Methods: A total of 15 pigs were randomised to ligation of left marginal arteries (infarction group, n=5), to TMLR of the left lateral wall using a holmium:yttrium-aluminium garnet (Ho:YAG) laser (laser group, n=5), and to both (laser-infarction group, n=5). All the animals were sacrificed 1 month after the procedure. Haemodynamics and echocardiography with segmental wall motion score were carried out at both time intervals (scale 0-3: 0, normal; 1, hypokinesia; 2, akinesia; 3, dyskinesia). Histology of the involved area was analysed. Results: Laser group showed no change of the segmental wall motion score of the involved area 30 min after the laser channels were made (score: 0±0). Infarction and laser-infarction groups both showed a persistent and definitive increase of the segmental wall motion score (at 30 min: 1.6±0.3 and 2±0, respectively; at 1 month: 1.8±0.2 and 1.8±0.4, respectively). These increases were all statistically significant in comparison with baseline values (P<0.5), however comparison between infarction and laser-infarction groups showed no significant difference. On macroscopic examination of the endocardial surface, no channel was opened. On histology, there were signs of neovascularisation around the channels in the laser group, whereas in the laser-infarction group the channels were embedded in the infarction scar. Conclusions: In this acute pig model, TMLR did not provide improvement of contractility of the ischaemic myocardium. To the degree that the present study pertains to the clinical setting, the results suggest that mechanisms other than blood flow through the channels should be considered, such as a laser-induced triggering of neovascularisation or neural destructio

The Significance of Angular K-feldspar Grains in Ancient Sandstones

In our studies of ancient sandstones, many of which are purported in the conventional literature to be eolian deposits, we frequently encountered angular K-feldspar sand grains. In particular, we encountered them while studying the Coconino Sandstone of Arizona, but we have found them in many other ancient sandstones as well. To gain some insights on the petrology of ancient “eolian” sandstones, we studied the petrology of a number small ergs in the western United States, beach and dune sands along the California and Oregon and reviewed the literature on the petrology of modern eolian and subaqueous deposits. In our literature review and from our own observations along the California and Oregon coastlines, we found that fluvial and shoreline processes are not sufficient to cause rounding of sand grains of any type, even after energetic and prolonged longshore transport and frequent tidal activity. Conversely, when sand grains are picked up by eolian processes and transported to coastal dunes, all species of mineral grains are quickly rounded, even over short distances. K-feldspar is rounded faster than quartz probably because it is softer and cleaves easier. We frequently encountered rounded K-feldspar grains in the small ergs we examined despite many of them being close in proximity to sources of angular K-feldspar sand grains. In larger ergs, all types of sand grains become quickly rounded and angular grains only occur if there are local fluvial or coastal sources for them. The frequent occurrence of angular K-feldspar grains that we found in ancient cross-bedded sandstones, purported to be made by eolian processes, causes us to question whether these deposits were made by eolian activities or not. The presence of angular K-feldspar may be one petrographic criterion for identifying ancient fluvial and marine deposits. The goal of this paper is to document the ubiquitous occurrence of angular K-feldspar grains in many supposed ancient cross-bedded sandstones. Coupled with other criteria, angular K-feldspar sand grains are a crucial piece of data that might be used to argue that these ancient sandstones were formed by aqueous rather than eolian processes

The Chanticleer, 1964-05-21

The editorially independent student produced weekly newspaper of Coastal Carolina University.https://digitalcommons.coastal.edu/chanticleer/1007/thumbnail.jp

Magneto-Optic Field Coupling in Optical Fiber Bragg Gratings

The invention is a magneto-optic coupled magnetic sensor that comprises a standard optical fiber Bragg grating system. The system includes an optical fiber with at least one Bragg grating therein. The optical fiber has at least an inner core and a cladding that surrounds the inner core. The optical fiber is part of an optical system that includes an interrogation device that provides a light wave through the optical fiber and a system to determine the change in the index of refraction of the optical fiber. The cladding of the optical fiber comprises at least a portion of which is made up of ferromagnetic particles so that the ferromagnetic particles are subject to the light wave provided by the interrogation system. When a magnetic field is present, the ferromagnetic particles change the optical properties of the sensor directly

The Evaluation of Laser Application in Surgery: A Review Article

There are several types of surgeries which use lasers in the operating room. Surgeons use lasers in general surgery or surgical specialties to cut, coagulate, and remove tissue. In modern medicine, the application of laser therapy is an attractive subject due to its minimal invasive effect. Today lasers are widely used in the treatment and diagnosis of many diseases such as various cancers, lithotripsy, ophthalmology, as well as dermatology and beauty procedures. Depending on the type of lasers, the wavelength and the delivery system, most lasers have replaced conventional surgical instruments for better wound healing results. Over time, by using many different tools and devices, new lasers have been created; as a result, they are used in a wide range of medical special cases. In this review, laser applications in surgery and its beneficial effects compared to previous surgeries with the aim of providing appropriate therapeutic and non-invasive solutions with minimal side effects after surgery are investigated

Analytic Time Evolution, Random Phase Approximation, and Green Functions for Matrix Product States

This chapter summarizes the Hartree–Fock (HF) and Matrix product states (MPS) approaches to stationary states to establish notation and illustrate the parallel structure of the theories. It derives analytic equations of motion for MPS time evolution using the Dirac–Frenkel variational principle. The chapter shows that the resulting evolution is optimal for MPS of fixed auxiliary dimension. It discusses the relationship of this approach to time evolution to schemes currently in use. The chapter explains how excitation energies and dynamical properties can be obtained from a linear eigenvalue problem. The relationship of this MPS random phase approximation (RPA) to other dynamical approaches for matrix product states is discussed. Finally, the chapter explores the site-based Green functions that emerge naturally within the theory of MPS and use the fluctuation-dissipation theory to analyze the stationary-state correlations introduced at the level of the MPS RPA

Effect of Various Laser Surface Treatments on Repair Shear Bond Strength of Aged Silorane-Based Composite

Introduction: Successful repair of composite restorations depends on a strong bond between the old composite and the repair composite. This study sought to assess the repair shear bond strength of aged silorane-based composite following surface treatment with Nd:YAG, Er,Cr:YSGG and CO2 lasers.Methods: Seventy-six Filtek silorane composite cylinders were fabricated and aged by 2 months of water storage at 37°C. The samples were randomly divided into 4 groups (n = 19) of no surface treatment (group 1) and surface treatment with Er,Cr:YSGG (group 2), Nd:YAG (group 3) and CO2 (group 4) lasers. The repair composite was applied and the shear bond strength was measured. The data were analyzed using one-way analysis of variance (ANOVA) and Tukey post-hoc test. Prior to the application of the repair composite, 2 samples were randomly selected from each group and topographic changes on their surfaces following laser irradiation were studied using a scanning electron microscope (SEM). Seventeen other samples were also fabricated for assessment of cohesive strength of composite.Results: The highest and the lowest mean bond strength values were 8.99 MPa and 6.69 MPa for Er,Cr:YSGG and control groups, respectively. The difference in the repair bond strength was statistically significant between the Er,Cr:YSGG and other groups. Bond strength of the control, Nd:YAG and CO2 groups was not significantly different. The SEM micrographs revealed variable degrees of ablation and surface roughness in laser-treated groups.Conclusion: Surface treatment with Er,Cr:YSGG laser significantly increase the repair bond strength of aged silorane-based composite resin

Foreland Magmatism during the Arabia–Eurasia Collision: Pliocene–Quaternary Activity of the Karacadağ Volcanic Complex, SW Turkey

Pliocene to Quaternary magmatism in the Karacadağ Volcanic Complex in SE Turkey occurred in the foreland region of the Arabia–Eurasia collision and can be divided into two phases. The earlier Karacadağ phase formed a north–south-trending volcanic ridge that erupted three groups of lavas. The same range of mantle sources contributed to the younger Ovabağ phase lavas, which were erupted from monogenetic cones to the east of the Karacadağ fissure. As at several other intraplate localities across the northern Arabian Plate this magmatism represents mixtures of melt from shallow, isotopically enriched mantle and from deeper, more depleted mantle. The deep source is similar to the depleted mantle invoked for other northern Arabian intraplate volcanic fields but at Karacadağ this source contained phlogopite. This source could be located in the shallow convecting mantle or may represent a metasomatic layer in the base of the lithosphere. There is no evidence for a contribution from the Afar mantle plume, as has been proposed elsewhere in northern Arabia. Melting during the Karacadağ and Ovabağ phases could have resulted from a combination of upwelling beneath weak or thinned lithosphere and restricted local extension of that weakened lithosphere as it collided with Eurasia. Tension associated with the collision focused magma of the Karacadağ phase into the elongate shield volcano of Mt. Karacadağ. The northern end of the fissure accommodated more extensive differentiation of magma, with isolated cases of crustal contamination, consistent with greater stress in the lithosphere closest to the collision. Most magma batches of the Karacadağ and Ovabağ phases differentiated by fractional crystallization at ∼5 MPa, near the boundary between the upper and lower crust. Magma batches dominated by melt from garnet lherzolite show evidence for restricted amounts of differentiation at ∼22·5 MPa, which is close to the base of the lithospheric mantle