Helium additions to MIG shielding gas - an economic option?

An investigation has been carried out to establish the technical and economic benefits of adding two levels of helium to a normal shielding gas. Technically no adverse issues were established using the two levels of helium, and the most significant positive one was the highly beneficial effects on travel speed increase and heat input decrease. Although helium gas carries a significant cost premium, the economic evaluation showed that overall this was a beneficial approach as the man-hour reduction associated with the welding process dominated the process cost effects

Evaluation of gas metal arc welding with alterating shielding gases for use on AA6082T6

Studies have been carried out to determine the effects of implementing alternating shielding gases for 6082T6 aluminium alloy welding. Alternating shielding gases is a newly developed method of supplying shielding gases to the weld area to enhance the efficiency of the standard Gas Metal Arc Welding (GMAW) process. This method involves discretely supplying two different shielding gases to the weld zone at a pre-determined frequency which creates a dynamic action in the weld pool. Several benefits have been identified in relation to supplying shielding gases in this manner including increased travel speed, reduced distortion, reduced porosity and, in the case of specific alternating frequencies, marginal improvements in mechanical properties. All in all, this method of shielding gas delivery presents attractive benefits to the manufacturing community, namely the increased productivity and quality in addition to a reduction in the amount of post-weld straightening required. However, the literature available on this advanced joining process is very scant, especially so for aluminium alloys. For this reason, an evaluation has been carried out on the application of alternating shielding gases for the GMAW process on 6082T6 aluminium alloys

Troubled waters: A reprisal of sea power and maritime importance in the turbulent years of the Texas revolt

The first section shall deal with the role the sea played following Mexican Independence. In the foreign colonization of Texas, Stephen F. Austin developed and designed his colonies similar to the agricultural communities of the American South that were built around nautical transportation from 1821–1829. The second area will deal with Mexican Texas from 1829 through 1832. By 1829 Mexico attempted to reinstate authority over Texas. Reaction to Mexican limitations was unified action through civil disobedience. As their rebellion brought the desired freedoms for the Texicans, they were encouraged to continue. The third discussion is the revolutionary period from 1832 to 1835. Following their political ideals, the colonists met to petition for separate statehood. Mexican inaction indicated approval of the political meeting. Later, when Mexico thwarted the Texican proposals, the colonists rebelled. This revolt was strengthened when a ship carrying Austin, the Laura, took up arms against a Mexican vessel

MIG gas shielding : Economic savings without detriment to quality

Over the years a number of claims have been made related to potential savings of the shielding gas used in the MIG process. A number of work streams have been set up to consider such areas from a technical and economic standpoint. The use of small helium additions has particular benefits and despite an increase in unit cost, the overriding benefits are achieved in reduced manhour cost. A similar situation has been established when using a high frequency process to switch shielding gases during welding. The outcome from this was very similar to that already described. Overlaid on these has been the increasing use of a technique that visualises actual gas flow during welding by the use of laser backlighting. Some preliminary work in this area is described particularly related to the effect of drafts on the gas distribution. A recent development on the market place is a piece of equipment, which regulates the gas flow automatically and synchronously with the welding current. Gas savings in the region of 50-60% have been obtained. Data has been produced to illustrate these benefits. The potential benefit of developing a computational fluid dynamic model of the gas flow is also described, and early development stages of the model shown. However, there will always exist the very basic management need to minimise leaks from the gas delivery systems

Tree Fern Apical Temperatures at the Royal Botanic Garden Edinburgh

Tree ferns are difficult to maintain out of doors in the British Isles except in western localities, where winter temperatures are moderated by the North Atlantic Drift, or in places where buildings provide a clement microclimate. The present study of tree-fern apical temperatures during winter was carried out on five trunked specimens of Dicksonia antarctica that had been grown satisfactorily out of doors for several years, while planted in the ground of a courtyard at the Royal Botanic Garden Edinburgh (RBGE). The plants were never wrapped or otherwise protected with thermal insulation during the winter months. An electric thermometer was inserted into the apical cleft of each plant in November 2003, and weekly readings of minimum and maximum temperature taken until April 2004. The ambient temperature of the air in the courtyard was similarly recorded and compared with the screen and grass temperatures at the RBGE weather station in the main botanic garden. The lowest grass and screen temperatures were respectively -11.2°C and -7.1°C, whereas the lowest courtyard and fern-apical temperatures were respectively -3.2°C and -0.8°C. Thus in the coldest period of that winter there was over 10°C difference in temperature between ground level in the main garden and a tree fern apical cleft in the sheltered courtyard. The tree ferns were not noticeably damaged by exposure of the apical cleft region to just below freezing point on a few occasions and the fronds stayed green. The five individual plants differed considerably in trunk height, diameter and volume. Regression analysis revealed that there was a significantly increasing thermal-insulating effect in the apical cleft associated with larger trunk diameters and volumes. The RBGE weather station temperatures during the winter of 2003-4 were unexceptional when compared with records from the previous 19 years. Thus the data from 2003-4 may be taken as representing a typical recent winter for this Edinburgh location. This study highlights the benefits of having detailed temperature measurements when assessing the winter-protective capabilities of a particular micro—environment for a semi-hardy species such as D. antarctica

The survival of witchcraft prosecutions and witch belief in South West Scotland

During the era of the Scottish witch-hunts, Dumfries and Galloway was one of the last regions to initiate witch prosecutions, but it was also one of the most reluctant to completely surrender all belief in witches until a comparatively late date. In the late seventeeth and early eighteenth centuries south-west Scotland, better known for the persecution of covenanters, took the practice of witchcraft and charming very seriously indeed, and for perhaps longer than other parts of Scotland, though the area has received surprisingly little scholarly investigation. The trial evidence is not incompatible with that found elsewhere though there is less demonic content. Accusations of witchcraft in this region were mostly concerned with the troubles of everyday life, agricultural problems, family tensions and disagreements between neighbours. From 1670 to about 1740, the very decades that were giving birth to the Scottish Enlightenment, learned interest in the supernatural was actually on the increase and the topic received an unprecedented level of questioning, investigation, and scrutiny. Ironically, the ‘superstitions’ that both church and state had been attempting to eradicate for some two hundred years were now being used to defend religion against the growing threat of atheism. The zeal of the ministers does seem to have contributed to the endurance of witch beliefs in the South West, as elsewhere. Against this backdrop, the survival of witch belief and the continued prosecution of witches in southwest Scotland is examined, thus contributing to our understanding of the individualistic nature of witch persecution and the various dynamics at play within the Scottish witch-hunting experience

Is there a role of synovial biopsy in drug development?

Rheumatoid arthritis (RA) is an autoimmune disease which causes significant pain, joint deformity, functional disability. The pathological hallmark of RA is inflammation of the synovium characterized by involvement of inflammatory and resident stromal cells, soluble mediators and signalling pathways leading to irreversible joint destruction. The treatment goal in RA has evolved over the last decade towards a target of disease remission that is achieved in less than a third of patients in clinical trials. The lack of therapeutic response to current treatments is suggestive of alternative drivers of RA pathogenesis that might serve as promising therapeutic targets. There are data to justify the use of synovial tissue in early drug development. Synovial tissue represents an appropriate compartment to be studied in patients with inflammatory arthritis and provides information that is distinct from peripheral blood. Modern techniques have made the procedure much more accessible and ultrasound guided biopsies represent a safe and acceptable option. Advances in analytic technologies allowing transcriptomic level of analysis can provide unique inside to target organ/tissue following the exposure to investigational medicinal product. However, there are still caveats with regard to both the choice of technique and analytical methods. Therefore the significance of synovial biopsy remains to be determined in future clinical trials. The aim of the current debate is to explore the potential for accessing and evaluating synovial tissue in early drug development, to summarize lessons we have learned from clinical trials and to discuss the challenges that have arisen so far

An Accurate Determination of the Optical Periodic Modulation in the X-Ray Binary SAX J1808.4-3658

We report on optical imaging of the X-ray binary SAX J1808.4-3658 with the 8-m Gemini South Telescope. The binary, containing an accretion-powered millisecond pulsar, appears to have a large periodic modulation in its quiescent optical emission. In order to clarify the origin of this modulation, we obtained three time-resolved $r'$-band light curves (LCs) of the source in five days. The LCs can be described by a sinusoid, and the long time-span between them allows us to determine optical period P=7251.9 s and phase 0.671 at MJD 54599.0 (TDB; phase 0.0 corresponds to the ascending node of the pulsar orbit), with uncertainties of 2.8 s and 0.008 (90 % confidence), respectively. This periodicity is highly consistent with the X-ray orbital ephemeris. By considering this consistency and the sinusoidal shape of the LCs, we rule out the possibility of the modulation arising from the accretion disk. Our study supports the previous suggestion that the X-ray pulsar becomes rotationally powered in quiescence, with its energy output irradiating the companion star, causing the optical modulation. While it has also been suggested that the accretion disk would be evaporated by the pulsar, we argue that the disk exists and gives rise to the persistent optical emission. The existence of the disk can be verified by long-term, multi-wavelength optical monitoring of the source in quiescence, as an increasing flux and spectral changes from the source would be expected based on the standard disk instability model.Comment: 7 pages, 3 figures. Accepted for publication in Ap

Properties of charmonium and bottomonium from lattice QCD with very fine lattices

Lattice methods are essential theoretical tools for performing calculations in quantum chromodynamics (QCD). To make theoretical predictions (or postdictions) of properties of hadrons, we must solve the theory of QCD which describes their constituent quarks — and conversely, to further our knowledge of quarks, which are fundamental constituents of matter, we must examine the properties of their hadronic bound states, since free quarks are not observed due to the phenomenon known as quark confinement. It is not possible to solve QCD analytically, and so we must turn to numerical methods such as lattice QCD. Despite being a well-established and mature formalism, lattice QCD has only really come into fruition over the last decade or so, developing in parallel with the advent of high-performance computing facilities. The available computing power is now sufficient to perform calculations on very fine lattices, with lattice spacings of about 0.06fm or less. These are beneficial for two reasons: firstly, they are closer to the continuum limit, meaning that continuum extrapolations are better controlled; and secondly, it is only on finer and finer lattices that we are able to accurately simulate heavier and heavier quarks, such as charm and bottom. We use very fine lattices from the MILC collaboration to determine multiple properties of heavyonium systems, in each case using the HISQ action for heavy valence quarks. Correlator fitting, and continuum and chiral extrapolations, are performed via Bayesian least-squares fitting methods. The first calculation simulates charmonium via charm quarks at their physical mass, as well as bottomonium, via multiple intermediate heavy quark masses and an extrapolation in this heavy mass. Notably, this is a fully relativistic method of calculating the bottom quark, and is complementary to effective-action methods such as NRQCD. We perform this calculation on gauge configurations with 2+1 flavours of quarks in the sea, and are able to accurately determine properties of the ground-state pseudoscalar and vector mesons in each system, including their decay constants, the hyperfine mass splitting, and the temporal moments of the vector correlators — which we also make use of to renormalise the vector current. To fully investigate some small anomalies in some of the vector results, we also repeat a subset of these calculations using a one-link instead of a local vector current. The second calculation represents an in-depth study of charmonium, including radial and orbital excitations as well as the ground states. We again simulate charm quarks at their physical mass, but this time on gauge configurations with 2+1+1 flavours of quarks in the sea, including those with light sea quarks at their physical masses. We also include a set of well-constructed smearing functions designed to increase the overlap of our correlators with the ground state, and therefore allow us to extract data on charmonium excited states more accurately. Specifically, we concentrate on conventional low-lying excited states in the charmonium system, and accurately extract various mass splittings in the spectrum (including the 1S hyperfine splitting, and the spin-averaged 2S − 1S splitting) as well as temporal moments of the vector correlator (which we again utilise in a renormalisation procedure), and decay constants of the ground-state pseudoscalar and vector. We also use the calculated mass splittings to accurately reconstruct a selected portion of the charmonium spectrum. This is the first time that we have used smeared operators with staggered quarks for this purpose, and so this calculation acts as a strong base upon which to build future work on excited states