Symmetric Differentiation on Time Scales

We define a symmetric derivative on an arbitrary nonempty closed subset of the real numbers and derive some of its properties. It is shown that real-valued functions defined on time scales that are neither delta nor nabla differentiable can be symmetric differentiable.Comment: This is a preprint of a paper whose final and definite form will be published in Applied Mathematics Letters. Submitted 30-Jul-2012; revised 07-Sept-2012; accepted 10-Sept-201

The efficacy of endoscopic therapy in bleeding peptic ulcer patients

Background. Endotherapy is the primary modality for the control ofbleeding from peptic ulceration.Objective. To assess the efficacy of endoscopic intervention for high-risk bleeding peptic ulcer disease and to benchmark our surgical and mortality rates.Methods. Two hundred and twenty-seven patients with pepticulcers stratified by Rockall and Forrest scores as being at high risk for rebleeding underwent therapeutic intervention (adrenalin injection) between January 2004 and December 2009. The median age of the patients was 57 years (range 19 - 87 years); 60% were males.Results. Primary endoscopic haemostasis failed in 51/227 patients (22.5%); 18 patients (7.9%) required surgery for bleeding not controlled at initial or second endoscopy; and 29 patients (12.8%) died, 12 by day 3 and 17 by day 30. Fifteen patients, all with significant medical co-morbidity, died after successful primary endotherapy, and 4 died after surgery. Surgical patients required more blood (odds ratio (OR) 1.45, p=0.0001) than those not undergoing surgery, but had similar mortality. Rebleeding was the only predictor of death in patients who died by day 3 (OR 18.77). A high Rockall score was the only predictor of death by day 30 (OR 1.98).Conclusion. The overall surgical and mortality rates were 7.9% and 12.8%, respectively. Over half the deaths resulted from medical co-morbidity, despite successful primary endotherapy. This finding is supported by the use of the Rockall score as a predictor of mortality at day 30. Improving the technical success of primary endoscopic haemostasis, currently 77.5%, has the potential to reduce rebleeding after primary endotherapy, a predictor of death at day 3 in this study

Magnetoelastic coupling in the cobalt adipate metal-organic framework from quasi-harmonic lattice dynamics

Magnetic interactions in hybrid materials are poorly understood compared to those in purely inorganic materials. The high flexibility of many metal-organic systems introduces a strong temperature dependence of the magnetic exchange interactions owing to changes in the crystal structure. Here, we study the cobalt adipate system, for which anisotropic thermal expansion was recently shown to be a result of magnetoelastic coupling. The combination of density functional theory with quasi-harmonic lattice dynamics is shown to be a powerful tool for describing temperature dependent thermodynamic potentials that determine magnetic interactions. It is demonstrated that the effect of phonons can be sufficient to switch the preference for ferromagnetic versus antiferromagnetic ordering

Interstellar medium disruption in the Centaurus A group

We present the results of a 21 cm neutral hydrogen (HI) line detection experiment in the direction of 18 low luminosity dwarf galaxies of the Centaurus A group, using the Australia Telescope National Facility 64m Parkes Radio Telescope and the Australia Telescope Compact Array. Five dwarfs have HI masses between M_HI=4x10^5 to M_HI=2.1x10^7 Msol and 0.04<M_HI/L_B<1.81 Msol L_{sol, B}^-1. The other 13 have upper-limits between M_HI<5x10^5 and M_HI<4x10^6 Msol (M_HI}/L_B<0.24 Msol L_{sol, B}^-1). Two of the mixed-morphology dwarfs remain undetected in HI, a situation that is in contrast to that of similar Local Group and Sculptor group objects where all contain significant amounts of neutral gas. There is a discontinuity in the HI properties of Centaurus A group low luminosity dwarfs that is unobserved amongst Sculptor group dwarfs. All objects fainter than M_B=-13 have either M_HI>10^7 Msol or M_HI<10^6 Msol. This gap may be explained by the ram pressure stripping mechanism at work in this dense environment where all galaxies with M_HI<10^7 Msol have been stripped of their gas. The required intergalactic medium density to achieve this is ~10^-3 cm^-3.Comment: 7 figures, 2 table

An ALMA survey of Sub-millimeter Galaxies in the Extended Chandra Deep Field South: Physical properties derived from ultraviolet-to-radio modelling

[abridged] The ALESS survey has followed-up a sample of 122 sub-millimeter sources in the Extended Chandra Deep Field South at 870um with ALMA, allowing to pinpoint the positions of sub-millimeter galaxies (SMGs) to 0.3'' and to find their precise counterparts at different wavelengths. This enabled the first compilation of the multi-wavelength spectral energy distributions (SEDs) of a statistically reliable survey of SMGs. In this paper, we present a new calibration of the MAGPHYS modelling code that is optimized to fit these UV-to-radio SEDs of z>1 star-forming galaxies using an energy balance technique to connect the emission from stellar populations, dust attenuation and dust emission in a physically consistent way. We derive statistically and physically robust estimates of the photometric redshifts and physical parameters for the ALESS SMGs. We find that they have a median stellar mass $M_\ast=(8.9\pm0.1)\times10^{10} M_\odot$, SFR$=280\pm70 M_\odot$/yr, overall V-band dust attenuation $A_V=1.9\pm0.2$ mag, dust mass M_\rm{dust}=(5.6\pm1.0)\times10^8 M_\odot, and average dust temperature Tdust~40 K. The average intrinsic SED of the ALESS SMGs resembles that of local ULIRGs in the IR range, but the stellar emission of our average SMG is brighter and bluer, indicating lower dust attenuation, possibly because they are more extended. We explore how the average SEDs vary with different parameters, and we provide a new set of SMG templates. To put the ALESS SMGs into context, we compare their stellar masses and SFRs with those of less actively star-forming galaxies at the same redshifts. At z~2, about half of the SMGs lie above the star-forming main sequence, while half are at the high-mass end of the sequence. At higher redshifts (z~3.5), the SMGs tend to have higher SFR and Mstar, but the fraction of SMGs that lie significantly above the main sequence decreases to less than a third.Comment: 22 pages, 14 figures, 2 tables. Accepted for publication in the Astrophysical Journal. The new MAGPHYS model libraries used in this paper will appear in www.iap.fr/magphys. The SMG SED templates shown in Section 6.1 are available at http://astronomy.swinburne.edu.au/~ecunha/ecunha/SED_Templates.htm

Student voice in work integrated learning scholarship: a review of teacher education and geographical sciences

Work integrated learning is an umbrella term that refers to the opportunities provided to university students to integrate knowledge of theory and practice as part of their degree program. As the role of students in higher education is evolving, we sought to develop our understanding of the role of students in the work integrated learning (WIL) space through exploring current literature on student voice. In this paper, we consider what has been reported about WIL in relation to student voice, how it has been represented, and how this has influenced practice. We undertook a systematic literature review for two different disciplines, one which represented an example of a professionally accredited undergraduate degree program (teacher education), and the other an example of a program with no professional accreditation (geographical sciences). The teacher education literature demonstrated more clearly the use of student voice to inform WIL within curriculum design. However, the geographical sciences literature did include examples of student voice being incorporated within the design of collaborative community-based forms of WIL. A role for students as researchers, who lead research and initiate curriculum change into WIL, was noticeably absent in both disciplinary sets of literature. The lack of evidence of the inclusion of students in the design, conduct, and analysis of WIL provides an invitation for SoTL scholars to redefine the role of students in this space

Asymmetric synthesis of secondary benzylic alcohols via arene chromium tricarbonyl complexes

ABSTRACT: The use of O-methyl-N-(alpha-methylbenzyl)hydroxylamine as a novel chiral auxiliary in asymmetric ortho-deprotonation of the (eta(6)-arene) chromium tricarbonyl complexes is described. Upon quenching of the resultant ortho-lithiated complex with an electrophile, 1,2-disubstituted (eta(6)-arene) chromium tricarbonyl complexes were obtained in good yield and excellent levels of diastereoselectivity.info:eu-repo/semantics/publishedVersio

Student voice in work integrated learning scholarship: A review of teacher education and geographical sciences

Work integrated learning is an umbrella term that refers to the opportunities provided to university students to integrate knowledge of theory and practice as part of their degree program. As the role of students in higher education is evolving, we sought to develop our understanding of the role of students in the work integrated learning (WIL) space through exploring current literature on student voice. In this paper, we consider what has been reported about WIL in relation to student voice, how it has been represented, and how this has influenced practice. We undertook a systematic literature review for two different disciplines, one which represented an example of a professionally accredited undergraduate degree program (teacher education), and the other an example of a program with no professional accreditation (geographical sciences). The teacher education literature demonstrated more clearly the use of student voice to inform WIL within curriculum design. However, the geographical sciences literature did include examples of student voice being incorporated within the design of collaborative community-based forms of WIL. A role for students as researchers, who lead research and initiate curriculum change into WIL, was noticeably absent in both disciplinary sets of literature. The lack of evidence of the inclusion of students in the design, conduct, and analysis of WIL provides an invitation for SoTL scholars to redefine the role of students in this space

An ALMA Survey of Submillimeter Galaxies in the Extended Chandra Deep Field South : The Redshift Distribution and Evolution of Submillimeter Galaxies

Accepted by ApJ. 45 pages, 16 figuresWe present the first photometric redshift distribution for a large unbiased sample of 870um selected submillimeter galaxies (SMGs) with robust identifications based on observations with the Atacama Large Millimeter Array (ALMA). In our analysis we consider 96 SMGs in the Extended Chandra Deep Field South, 77 of which have 4-19 band, optical-near-infrared, photometry. We model the Spectral Energy Distributions (SEDs) for these 77 SMGs, deriving a median photometric redshift of z=2.3+/-0.1. The remaining 19 SMGs have insufficient optical or near-infrared photometry to derive photometric redshifts, but a stacking analysis of IRAC and Herschel observations confirms they are not spurious. Assuming these sources have an absolute H-band magnitude distribution comparable to that of a complete sample of z~1-2 SMGs, we demonstrate that the undetected SMGs lie at higher redshifts, raising the median redshift for SMGs to z=2.5+/-0.2. More critically we show that the proportion of galaxies undergoing an SMG phase at z>3 is 35+/-5% of the total population. We derive a median stellar mass for SMGs of Mstar=(8+/-1)x10^10Mo, but caution that there are significant systematic uncertainties in our stellar mass estimate, up to x5 for individual sources. We compare our sample of SMGs to a volume-limited, morphologically classified sample of ellipticals in the local Universe. Assuming the star formation activity in SMGs has a timescale of ~100Myr we show that their descendants at z~0 would have a space density and M_H distribution which are in good agreement with those of local ellipticals. In addition the inferred mass-weighted ages of the local ellipticals broadly agree with the look-back times of the SMG events. Taken together, these results are consistent with a simple model that identifies SMGs as events that form most of the stars seen in the majority of luminous elliptical galaxies at the present day.Peer reviewe