3,470 research outputs found
The Asperian Design
Reality is two-fold, composed of the lighted world as revealed in Genesis, and the darker primordiality which preceded it. The illuminated represents that which the human mind can comprehend, manipulate and re-order to its will: a âdesignedâ and mechanical universe of parts. But behind it, in the backspace of reality, remains the darkness. A formless state of pre-creation, the darkness exists as an endless series of intertwining âsignaturesâ â single possibilities waiting to be created in the illuminated forefront of reality. Permitting each and every part of the lighted world to be connected to the rest, it possesses a âdesignâ all of its own. The question is, if we are blind in the dark, how could we ever come to know it
The Field
Life is a battlefield onto which we are thrown at birth, with only fate and fortune settling upon where we land. Wherever we land, whether it's on the front lines or surrounded by a network of defenses, we are all asking the same question: why are we here?
The problem with this question, however, is that we tend to answer it from our own relative positions, and so we all arrive at different conclusions. The many answers we've created have filled the field. They have become banners that are raised high so that we can see and follow them. These banners are always at risk of being toppled though; always at risk of losing their capacity for belief. But then, what if belief is more than a mere by-product of our universal search? What if belief can change the very fabric of this field? That is, what if truth is actually irrelevant, and the only real thing that makes up this battlefield is the belief, and consequently the collective will, which we invest in our answers
Metallicity in the Galactic Center: The Arches cluster
We present a quantitative spectral analysis of five very massive stars in the
Arches cluster, located near the Galactic center, to determine stellar
parameters, stellar wind properties and, most importantly, metallicity content.
The analysis uses a new technique, presented here for the first time, and uses
line-blanketed NLTE wind/atmosphere models fit to high-resolution near-infrared
spectra of late-type nitrogen-rich Wolf-Rayet stars and OfI+ stars in the
cluster. It relies on the fact that massive stars reach a maximum nitrogen
abundance that is related to initial metallicity when they are in the WNL
phase. We determine the present-day nitrogen abundance of the WNL stars in the
Arches cluster to be 1.6% (mass fraction) and constrain the stellar metallicity
in the cluster to be solar. This result is invariant to assumptions about the
mass-luminosity relationship, the mass-loss rates, and rotation speeds. In
addition, from this analysis, we find the age of the Arches cluster to be
2-2.5Myr, assuming coeval formation
Unlocking Galactic Wolf-Rayet stars with Gaia DR2 I: Distances and absolute magnitudes
We obtain distances to 383 Galactic Wolf-Rayet (WR) stars from Gaia DR2 parallaxes and Bayesian methods, with a prior based on HII regions and dust extinction. Distances agree with those from Bailer-Jones et al. for stars up to 2 kpc from the Sun, though deviate thereafter due to differing priors, leading to modest reductions in luminosities for recent WR spectroscopic results. We calculate visual and K-band absolute magnitudes, accounting for dust extinction contributions and binarity, and identify 188 stars with reliable absolute magnitudes. For WR and O stars within 2 kpc, we find a WR/O ratio of 0.1. The distances are used to generate absolute magnitude calibrations and obtain the Gaia colour magnitude diagram for WR stars. Average vWR-band absolute magnitudes for WN stars range from â3.6 mag (WN3â4) to â7.0 mag (WN8â9ha), and â3.1 (WO2â4) to â4.6 mag (WC9), with standard deviations of âŒ0.6 mag. Using HII region scale heights, we identify 31 WR stars at large (3Ï, |z|â„156 pc) distances from the mid-plane as potential runaways accounting for the Galactic warp, of which only 4 involve WN8â9 stars, contrary to previous claims
Perineal massage in labour and prevention of perineal trauma: randomised controlled trial
Objective: To determine the effects of perineal massage in the second stage of labour on perineal outcomes. Design: Randomised controlled trial. Participants: At 36 weeks' gestation, women expecting normal birth of a singleton were asked to join the study. Women became eligible to be randomised in labour if they progressed to full dilatation of the cervix or 8 cm or more if nulliparous or 5 cm or more if multiparous. 1340 were randomised into the trial. Intervention: Massage and stretching of the perineum during the second stage of labour with a water soluble lubricant. Main outcome measures: Primary outcomes: rates of intact perineum, episiotomies, and first, second, third, and fourth degree tears. Secondary outcomes: pain at three and 10 days postpartum and pain, dyspareunia, resumption of sexual intercourse, and urinary and faecal incontinence and urgency three months postpartum. Results: Rates of intact perineums, first and second degree tears, and episiotomies were similar in the massage and the control groups. There were fewer third degree tears in the massage group (12 (1.7%) v 23 (3.6%); absolute risk 2.11, relative risk 0.45; 95% confidence interval 0.23 to 0.93, P<0.04), though the trial was underpowered to measure this rarer outcome. Groups did not differ in any of the secondary outcomes at the three assessment points. Conclusions: The practice of perineal massage in labour does not increase the likelihood of an intact perineum or reduce the risk of pain, dyspareunia, or urinary and faecal problems.Georgina Stamp, Gillian Kruzins, Caroline Crowthe
A downward revision to the distance of the 1806-20 cluster and associated magnetar from Gemini near-Infrared spectroscopy
We present H- and K-band spectroscopy of OB and Wolf-Rayet (WR) members of
the Milky Way cluster 1806-20 (G10.0-0.3), to obtain a revised cluster distance
of relevance to the 2004 giant flare from the SGR 1806-20 magnetar. From GNIRS
spectroscopy obtained with Gemini South, four candidate OB stars are confirmed
as late O/early B supergiants, while we support previous mid WN and late WC
classifications for two WR stars. Based upon an absolute Ks-band magnitude
calibration for B supergiants and WR stars, and near-IR photometry from NIRI at
Gemini North plus archival VLT/ISAAC datasets, we obtain a cluster distance
modulus of 14.7+/-0.35 mag. The known stellar content of the 1806-20 cluster
suggests an age of 3-5 Myr, from which theoretical isochrone fits infer a
distance modulus of 14.7+/-0.7 mag. Together, our results favour a distance
modulus of 14.7+/-0.4 mag (8.7^+1.8_-1.5 kpc) to the 1806-20 cluster, which is
significantly lower than the nominal 15 kpc distance to the magnetar. For our
preferred distance, the peak luminosity of the December 2004 giant flare is
reduced by a factor of three to 7 X 10^46 erg/s, such that the contamination of
BATSE short gamma ray bursts (GRB's) from giant flares of extragalactic
magnetars is reduced to a few percent. We infer a magnetar progenitor mass of
~48^+20_-8 Msun, in close agreement with that obtained recently for the
magnetar in Westerlund 1.Comment: 6 pages, 4 figures, accepted for MNRAS Letter
Evolution of precipitates, in particular cruciform and cuboid particles, during simulated direct charging of thin slab cast vanadium microalloyed steels
A study has been undertaken of four vanadium based steels which have been processed by a simulated direct charging route using processing parameters typical of thin slab casting, where the cast product has a thickness of 50 to 80mm ( in this study 50 mm) and is fed directly to a furnace to equalise the microstructure prior to rolling. In the direct charging process, cooling rates are faster, equalisation times shorter and the amount of deformation introduced during rolling less than in conventional practice. Samples in this study were quenched after casting, after equalisation, after 4th rolling pass and after coiling, to follow the evolution of microstructure. The mechanical and toughness properties and the microstructural features might be expected to differ from equivalent steels, which have undergone conventional processing. The four low carbon steels (~0.06wt%) which were studied contained 0.1wt%V (V-N), 0.1wt%V and 0.010wt%Ti (V-Ti), 0.1wt%V and 0.03wt%Nb (V-Nb), and 0.1wt%V, 0.03wt%Nb and 0.007wt%Ti (V-Nb-Ti). Steels V-N and V-Ti contained around 0.02wt% N, while the other two contained about 0.01wt%N. The as-cast steels were heated at three equalising temperatures of 1050C, 1100C or 1200C and held for 30-60 minutes prior to rolling. Optical microscopy and analytical electron microscopy, including parallel electron energy loss spectroscopy (PEELS), were used to characterise the precipitates. In the as-cast condition, dendrites and plates were found. Cuboid particles were seen at this stage in Steel V-Ti, but they appeared only in the other steels after equalization. In addition, in the final product of all the steels, fine particles were seen, but it was only in the two titanium steels that cruciform precipitates were present. PEELS analysis showed that the dendrites, plates, cuboids, cruciforms and fine precipitates were essentially nitrides. The two Ti steels had better toughness than the other steels but inferior lower yield stress values. This was thought to be, in part, due to the formation of cruciform precipitates in austenite, thereby removing nitrogen and the microalloying elements which would have been expected to precipitate in ferrite as dispersion hardening particles
SwSt 1: an O-rich planetary nebula around a C-rich central star
The hydrogen-deficient carbon-rich [WCL] type central star HD167362 and its
oxygen-rich planetary nebula (PN) SwSt~1 are investigated. The nebular
chemistry might indicate a recent origin for the carbon-rich stellar spectrum.
Its stellar and nebular properties might therefore provide further
understanding of the origin of the [WCL] central star class. The UV-IR stellar
spectra are modelled with state of the codes and show ~40kK central star with a
wind and a C/O~3, indicative of efficient third dredge-up. The synthetic
stellar flux distribution is used to model the high density, compact PN, which
has a solar C/O ratio, is still enshrouded by 1200K and 230K dust shells and,
reported here for the first time, in molecular hydrogen. Although it appears
that the change in C/O ratio has been recent, the published spectroscopy since
1895 has been re-examined and no clear spectral change is seen. If an event
occurred that has turned it into a hydrogen-deficient central star, it did not
happen in the last 100 years.Comment: 31 pages, 19 figures (some are gif files), MNRAS in pres
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