Randomized comparison of ultrasonic aspiration versus conventional electrocautery for dissection of the human internal thoracic artery

AbstractThe most common technique currently employed to harvest the internal thoracic artery for coronary artery bypass grafting is conventional electrocautery. This study compared an alternative method, electrocautery with an ultrasonic aspirator, for harvesting the internal thoracic artery. Patients were randomly assigned to one of six experimental groups (conventional electrocautery, ultrasonic aspirator at settings of 60%, 80%, and 100% power output, and ultrasonic aspirator in 100% CAVI-Pulse modes 1 and 3). Ring segments of internal thoracic artery were studied in an organ bath. Contraction responses were elicited with 123 mmol/L potassium physiologic salt solution, KPSS, KPSS solution containing noradrenaline, and a cumulative noradrenaline dose-contraction curve. Relaxation studies were performed with the vasodilators acetylcholine, bradykinin, and sodium nitroprusside. Forty percent of the electrocauterized vessels were traumatized or damaged and failed to respond to contractile stimuli, whereas only 10% of the vessels in ultrasonic aspirator groups 60%, 80%, and 100% failed to respond. All vessels in the group harvested by ultrasonic aspirator in 100% CAVI-Pulse mode 1 responded, whereas 20% of the vessels in the group harvested by ultrasonic aspirator in 100% CAVI-Pulse mode 3 failed to respond. All settings of electrocautery with an ultrasonic aspirator produced a greater contractile response to KPSS and noradrenaline. Acetylcholine and sodium nitroprusside produced similar relaxations in all groups, but the bradykinin responses were significantly improved in all groups undergoing 100% electrocautery with an ultrasonic aspirator. These results suggest that 100% electrocautery with an ultrasonic aspirator, particularly in 100% CAVI-Pulse mode 1, resulted in less damage and trauma than conventional electrocautery during harvesting of the internal thoracic artery. (J T HORAC CARDIOVASC SURG 1996;111:1194-9

RE: pedagogy – after neutrality

Within the UK and in many parts of the world, official accounts of what it is to make sense of religion are framed within a rhetorics of neutrality in which such study is premised upon the possibility of dispassionate engagement and analysis. This paper, which is largely theoretical in scope, explores both the affordances and the costs of such an approach which has become ‘black boxed’ on account of the work that it achieves. A series of new orientations within the academy that are broadly associated with post-structuralist philosophies, feminist and post-colonial studies, together with insights from Science and Technology Studies, question the plausibility of these claims for neutrality whilst in turn raising a series of new questions and priorities. It therefore becomes necessary to re-think and re-frame what it is to make sense of religious and cultural difference after neutrality. The gathering and co-ordination of new planes of sense-making that are responsive to an emergent series of epistemological, ontological, and ethical orientations are considered. Some of the distinctive pedagogical implications of such an approach that engages material practice, difference and uncertainty are then entertained

Energetic particle influence on the Earth's atmosphere

This manuscript gives an up-to-date and comprehensive overview of the effects of energetic particle precipitation (EPP) onto the whole atmosphere, from the lower thermosphere/mesosphere through the stratosphere and troposphere, to the surface. The paper summarizes the different sources and energies of particles, principally galactic cosmic rays (GCRs), solar energetic particles (SEPs) and energetic electron precipitation (EEP). All the proposed mechanisms by which EPP can affect the atmosphere are discussed, including chemical changes in the upper atmosphere and lower thermosphere, chemistry-dynamics feedbacks, the global electric circuit and cloud formation. The role of energetic particles in Earth’s atmosphere is a multi-disciplinary problem that requires expertise from a range of scientific backgrounds. To assist with this synergy, summary tables are provided, which are intended to evaluate the level of current knowledge of the effects of energetic particles on processes in the entire atmosphere

Radiogenic and stable isotope constraints on the genesis of the Eloise Cu-Au deposit, Cloncurry district, Australia

New radiogenic (40Ar/39Ar) and stable (oxygen, hydrogen, and sulfur) isotope analyses of metamorphic and\ud metasomatic minerals constrain the age, metasomatic evolution, and genesis of the Eloise Cu-Au deposit (3.1\ud Mt @ 5.5% Cu, 1.4 g/t Au, and 16 g/t Ag). Biotite from a pre- to syn-D2-stage vein has an 40Ar/39Ar age of 1555\ud ± 4 Ma which is interpreted to coincide with a regional metamorphic event synchronous with D2. Six later stages of alteration and mineralization are recognized, all of which postdate peak metamorphism and D2. Stages I to III are volumetrically the most significant and comprise early albitization (stage I), quartz-hornblende-biotite veins and alteration (stage II), and Cu-Au mineralization (stage III). Stages IV, V, and VI are localized vein events and postdate the main Cu-Au mineralization. Stage II vein and alteration hornblendes have 40Ar/39Ar ages of 1530 ± 3 Ma. Biotite from the same stage has an 40Ar/39Ar age of 1521 ± 3 Ma. Muscovite from a postore shear zone has an 40Ar/39Ar age of 1514 ± 3 Ma. These results provide a maximum (ca. 1530 Ma) and minimum (ca. 1514 Ma) age for the mineralizing event. However, the intimate relationship between stage II\ud mafic-silicate veins and alteration and the stage III Cu-Au event combined with fluid inclusion results which indicate that a cooling, evolving high-salinity fluid was responsible for both stages suggests that the older age\ud is likely to be closer to the age of mineralization. The stage II biotite age of ca. 1521 Ma is interpreted to record\ud thermal resetting during postore ductile deformation. The results suggest that micas in the Cloncurry district\ud are more susceptible to later thermal resetting than amphiboles which may have significant implications for deposits which have only been dated by micas. Quartz from stages II, III, and IV have δ18Oquartz values ranging between 10.1 and 11.9 per mil. Stage II biotite has a lower δ18O composition (5.6‰) than biotite from a pre-D2 vein (6.9‰), but both have identical δD compositions (–84‰). Stage II hornblende has lower δ18O (6.8 and 7.4‰) and δD (–88 and –90‰) values than does stage III actinolite (8.0 and –84‰, respectively). The δ34S values for chalcopyrite, pyrrhotite, and pyrite fall in a narrow range between 0.0 and 2.3 per mil. A distinct trend can be recognized with δ34S values becoming progressively greater from south to north, thus reflecting the zoned alteration system (magnetitepyrite-rich in the south through to pyrrhotite-rich in the north). The change in mineralogy and sulfur isotope values may be due to cooling and sulfidation processes which resulted in changes in oxygen and sulfur fugacities. The oxygen, hydrogen, and sulfur isotope data, combined with high-temperature and high-salinity fluid inclusion data, indicate a predominantly magmatic origin for the ore forming fluids. The deposit is interpreted\ud to have formed from magmatic hydrothermal fluids which were tapped by deep-seated crustal structures

The Lightning Creek sill complex, Cloncurry district, northwest Queensland: a source of fluids for Fe oxide Cu-Au mineralization and sodic-calcic alteration

The Lightning Creek Cu-Au prospect is hosted by a cogenetic suite of plutonic, I-type granitoids. The dominant rock type is a porphyritic quartz monzodiorite that is intruded by more fractionated rocks, including monzogranite and alkali feldspar granite. A series of flat-lying sills are interpreted to be late-stage differentiates, based on their timing, mineralogy, and chemistry.\ud \ud In parts of the prospect there is pervasive sodic-calcic alteration (pyroxene after amphibole, albite after K feldspar and oligoclase) of the plutonic rocks. This alteration predates sill emplacement and is unrelated to veining or fracturing of any kind. The presence of small amounts of carbonate in the altered rocks suggests that the fluids were CO2 bearing. Quartz and feldspar separates from these altered rocks have oxygen isotope compositions similar to those from fresh quartz-monzodiorite, suggesting that the fluids were hot and of magmatic composition. Sodium and Ca were added and K, Fe, Cl, and Cu were stripped during what is interpreted as an autometasomatic event.\ud \ud The sills display considerable textural and mineralogical complexity and evolved from equigranular, quartzofeldspathic rocks (aplites), with magmatic chemistry, to unusual Fe-rich rocks (albite-magnetite-quartz) that exhibit a range of bizarre spherulitic textures. Some of the albite and magnetite in the sills is secondary. Albite forms pseudomorphs after K feldspar (Na-Fe ± Ca alteration) along sill margins and within sills, at the contacts between different textural zones. Halos of disseminated magnetite + clinopyroxene (Fe-Ca ± Na alteration) are developed adjacent to early magnetite veins.\ud \ud Fluid inclusion studies indicate that these rocks crystallized at temperatures in excess of 500°C and at pressures in excess of 1.5 kbar. The range of spherulitic textures is taken to indicate crystallization under hydrous conditions with the episodic release of a fluid phase. This magmatic fluid phase was dominated by H2O, CO2, and chlorine and underwent phase separation into a CO2-rich vapor and a hypersaline brine (33–55 wt % NaCl equiv). The hypersaline fluid was enriched in Fe (~10 wt %) and Cu (~1 wt %, PIXE analysis), in addition to Na, K, and Ca. Where this fluid was retained within Fe-rich portions of the sills, it caused Ca-Fe ± Na alteration (pyroxene-albite ± magnetite growth at the expense of quartz). Where the fluid was expelled from the sills, it produced quartz-magnetite ± clinopyroxene ± albite veins (broadly coeval with the early magnetite veins). Although rich in Cu, these granitoid-derived magmatic fluids did not generate significant Cu(-Au) mineralization, perhaps because of the high temperatures involved and/or a lack of reduced sulfur in the fluids or host rock. However, the amount of iron present is estimated (from the aeromagnetic anomaly) to be in excess of 2,000 million tonnes (Mt).\ud \ud A later generation of calcite ± chlorite ± pyrite ± chalcopyrite veins contain traces of Cu-Au mineralization. Fluid inclusion and stable isotope work indicate that these veins probably crystallized from cooler (<200°C), more dilute (15–28 wt % NaCl equiv) fluids, perhaps generated by the admixture of a meteoric component.\ud \ud The conclusions reached in this study have implications for understanding the genesis of Fe oxide Cu-Au deposits and related sodic-calcic alteration. The study indicates the potential for CO2-rich granitoid magmas to evolve hypersaline, Fe- and Cu-rich fluids capable of causing intense magnetite veining and Cu(-Au?) mineralization. Autometasomatic sodic-calcic alteration of the granitoids may be an important precursor to mineralization, contributing Fe, K, Cu, and Cl to the magmatic fluids

Age constraints on the tectonothermal evolution of the Selwyn Zone, Eastern Fold Belt, Mount Isa Inlier

The Selwyn Zone is characterized by multiple ductile deformation and metamorphic events. There is general consensus that early in the Isan Orogeny there were both extensional and thrust events that produced bedding-parallel foliation (Sbp). We propose that these were followed by the D1 event that resulted in a regional steep east–west foliation, and that the Snake Creek Anticline and the dominant S2a regional foliation formed as upright north–south structures. Local overturning of D2 structures was due to subsequent localized deformation (D2b) that resulted in structures with flat-lying axial planes. D3 and D4 produced steep upright folds and crenulations with north–northwest and northeast trending axial surfaces. Metamorphism, largely controlled by the emplacement of mafic rocks, is dominantly low pressure, but the P–T–t path is complex. Early growth of cordierite (M1) followed by andalusite, was succeeded by a clockwise medium pressure loop of ca. 500–600 MPa in the northern Snake Creek Anticline, as indicated by early D2a kyanite growth. The metamorphic peak during D2 was around 580 °C and 400 MPa at the sillimanite isograd and reached a maximum of around 670 °C and 400–500 MPa in the migmatitic sillimanite K-feldspar zone at the Cannington and Osborne mines. Previous age determinations for the metamorphic peak of ∼1580–1600 Ma are confirmed with new electron microprobe dating of monazite, whereas an age grouping of 1600–1630 Ma may represent the D1 (M2) event. Additional ages in the range 1640–1680 Ma are recorded in albitites from the Soldiers Cap Group, and it is suggested that they formed by infiltration of hydrothermal fluids during extension and the emplacement of mafic sills. This is supported by SHRIMP dating of zircon from a trondhjemite lens in a largely mafic sill complex in the Snake Creek Anticline that provided an age of 1686 ± 8 Ma, also indicating that at least part of the Soldiers Cap Group is older than previously indicated. A zircon SHRIMP age of 1527 ± 4 Ma was obtained for a sample of albitized Saxby Granite. This age also represents the D4 (M6) event, and is the timing of the extensive brecciation and albitization of calc-silicate rocks of the Corella Formation in the Selwyn Zone

Waste to resource: use of water treatment residual for increased maize productivity and micronutrient content

Soil degradation, which is linked to poor nutrient management, remains a major constraint to sustained crop production in smallholder urban agriculture (UA) in sub-Saharan Africa (SSA). While organic nutrient resources are often used in UA to complement mineral fertilizers in soil fertility management, they are usually scarce and of poor quality to provide optimum nutrients for crop uptake. Alternative soil nutrient management options are required. This study, therefore, evaluates the short-term benefits of applying an aluminium-based water treatment residual (Al-WTR), in combination with compost and inorganic P fertilizer, on soil chemical properties, and maize (Zea mays L.) productivity and nutrient uptake. An eight-week greenhouse experiment was established with 12 treatments consisting of soil, Al-WTR and compost (with or without P fertilizer). The co-amendment (10% Al-WTR + 10% compost) produced maize shoot biomass of 3.92 ± 0.16 g at 5 weeks after emergence, significantly (p < 0.05) out-yielding the unamended control which yielded 1.33 ± 0.17 g. The addition of P fertilizer to the co-amendment further increased maize shoot yield by about twofold (7.23 ± 0.07 g). The co-amendment (10% Al-WTR + 10% C) with P increased maize uptake of zinc (Zn), copper (Cu) and manganese (Mn), compared with 10% C + P. Overall, the results demonstrate that combining Al-WTR, compost and P fertilizer increases maize productivity and micronutrient uptake in comparison with single amendments of compost and fertilizer. The enhanced micronutrient uptake can potentially improve maize grain quality, and subsequently human nutrition for the urban population of SSA, partly addressing the UN’s Sustainable Development Goal number 3 of improving diets

Epidote-clinozoisite as a hyperspectral tool in exploration for Archean gold

Hyperspectral analysis at seven gold deposits within the eastern Yilgarn Craton of Western Australia has revealed significant occurrences of previously unrecognised clinozoisite, and spatial relationships between the distribution of clinozoisite, epidote and gold deposits. Here we report the development of an index to allow the systematic spectral mapping of the epidote-clinozoisite solid solution. The combination of the wavelength position and depth of the 1550 nm absorption was used to characterise the solid-solution series spectrally. The spectral responses from CSIRO HyChips (TM), fitted with an Analytical Spectral Devices (ASD) FieldSpec-3 spectrometer, and a SisuCHEMA (TM) spectral-imaging camera were calibrated against electron microbe analyses of epidote-clinozoisite. The spectral-imaging camera helped resolve correlations for samples with complex paragenetic histories. Textural studies found genetic links between epidote and Mg-chlorite, and between clinozoisite and Fechlorite, with each mineral combination part of separate, diagnostic hydrothermal assemblages. Spectra from epidote-clinozoisite-dominated veins showed that shifts in the 2250 nm absorption correlate with epidote-clinozoisite composition and not with chlorite composition, and that coexisting amphibole phases have a closer compositional tie than chlorite in the given samples. The genetic affiliation, yet compositional discordance, between coexisting epidote-clinozoisite and chlorite suggests that the compositional spectral index associated with each are wholly independent, but in combination are diagnostic for the mapping of separate hydrothermal assemblages. Of the newly defined compositional relationships, vein-hosted clinozoisite was found to be a proxy for pre-existing structurally-controlled hydrothermal tschermakite. A comparison of spectral and stable isotopic characteristics from diamond drill hole CD5026, St Ives mining camp, shows correlations between the epidote-clinozoisite spectral index and delta(13)C of carbonate and delta(34)S of sulfide. Such correlations imply a redox control on the distribution of clinozoisite and epidote, and mean that the spectral logging of epidote-clinozoisite transitions can serve as a proxy for mapping paleoredox gradients