To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure firstname.lastname@example.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Observations at low frequencies (<8GHz) are dominated by distinct direction dependent ionospheric propagation errors, which place a very tight limit on the angular separation of a suitable phase referencing calibrator and astrometry. To increase the capability for high precision astrometric measurements an effective calibration strategy of the systematic ionospheric propagation effects that is widely applicable is required. The MultiView technique holds the key to the compensation of atmospheric spatial-structure errors, by using observations of multiple calibrators and two dimensional interpolation. In this paper we present the first demonstration of the power of MultiView using three calibrators, several degrees from the target, along with a comparative study of the astrometric accuracy between MultiView and phase-referencing techniques. MultiView calibration provides an order of magnitude improvement in astrometry with respect to conventional phase referencing, achieving ~100micro-arcseconds astrometry errors in a single epoch of observations, effectively reaching the thermal noise limit.
We present the results from the Australian Long Baseline Array (LBA) observations of the ground- and excited-state OH masers at high resolutions towards the massive star-forming region G351.417+0.645 in 2012. We obtain the most accurate spatial gradient of magnetic fields at ground state transitions and verify the reliability of magnetic field strengths measured from previous lower resolution observations. In comparison with previous LBA observations in 2001 at 6.0 GHz, we identified several matched Zeeman pairs. We found that the OH maser features have no significant change of magnetic field strengths and directions with small internal proper motions, implying quite stable physical conditions. Additionally, we found that 1665- and 6035-MHz OH maser features reveal the same trend of reversal of magnetic fields. Moreover, we also analyzed the physical conditions at different locations from the coincidence of different OH maser transitions based on current OH maser models.
We report on the astrometric registration of VLBI images of the SiO and H2O masers in OH 231.8+4.2, the iconic Proto-Planetary Nebula also known as the Calabash nebula, using the KVN and Source/Frequency Phase Referencing. This, for the first time, robustly confirms the alignment of the SiO masers, close to the AGB star, which drives the bi-lobe structure with the water masers in the out-flow.
The Zadko telescope is a 1 m f/4 Cassegrain telescope, situated in the state of Western Australia about 80-km north of Perth. The facility plays a niche role in Australian astronomy, as it is the only meter class facility in Australia dedicated to automated follow-up imaging of alerts or triggers received from different external instruments/detectors spanning the entire electromagnetic spectrum. Furthermore, the location of the facility at a longitude not covered by other meter class facilities provides an important resource for time critical projects. This paper reviews the status of the Zadko facility and science projects since it began robotic operations in March 2010. We report on major upgrades to the infrastructure and equipment (2012–2014) that has resulted in significantly improved robotic operations. Second, we review the core science projects, which include automated rapid follow-up of gamma ray burst (GRB) optical afterglows, imaging of neutrino counterpart candidates from the ANTARES neutrino observatory, photometry of rare (Barbarian) asteroids, supernovae searches in nearby galaxies. Finally, we discuss participation in newly commencing international projects, including the optical follow-up of gravitational wave (GW) candidates from the United States and European GW observatory network and present first tests for very low latency follow-up of fast radio bursts. In the context of these projects, we outline plans for a future upgrade that will optimise the facility for alert triggered imaging from the radio, optical, high-energy, neutrino, and GW bands.
Among several potential animal models that can be used for adipogenic studies, Wagyu cattle is the one that presents unique molecular mechanisms underlying the deposit of substantial amounts of intramuscular fat. As such, this review is focused on current knowledge of such mechanisms related to adipose tissue deposition using Wagyu cattle as model. So abundant is the lipid accumulation in the skeletal muscles of these animals that in many cases, the muscle cross-sectional area appears more white (adipose tissue) than red (muscle fibers). This enhanced marbling accumulation is morphologically similar to that seen in numerous skeletal muscle dysfunctions, disease states and myopathies; this might indicate cross-similar mechanisms between such dysfunctions and fat deposition in Wagyu breed. Animal models can be used not only for a better understanding of fat deposition in livestock, but also as models to an increased comprehension on molecular mechanisms behind human conditions. This revision underlies some of the complex molecular processes of fat deposition in animals.
The first observations by a worldwide network of advanced interferometric gravitational wave detectors offer a unique opportunity for the astronomical community. At design sensitivity, these facilities will be able to detect coalescing binary neutron stars to distances approaching 400 Mpc, and neutron star–black hole systems to 1 Gpc. Both of these sources are associated with gamma-ray bursts which are known to emit across the entire electromagnetic spectrum. Gravitational wave detections provide the opportunity for ‘multi-messenger’ observations, combining gravitational wave with electromagnetic, cosmic ray, or neutrino observations. This review provides an overview of how Australian astronomical facilities and collaborations with the gravitational wave community can contribute to this new era of discovery, via contemporaneous follow-up observations from the radio to the optical and high energy. We discuss some of the frontier discoveries that will be made possible when this new window to the Universe is opened.
The abundance and cross-linking of intramuscular connective tissue contributes to the background toughness of meat, and is thus undesirable. Connective tissue is mainly synthesized by intramuscular fibroblasts. Myocytes, adipocytes and fibroblasts are derived from a common pool of progenitor cells during the early embryonic development. It appears that multipotent mesenchymal stem cells first diverge into either myogenic or non-myogenic lineages; non-myogenic mesenchymal progenitors then develop into the stromal-vascular fraction of skeletal muscle wherein adipocytes, fibroblasts and derived mesenchymal progenitors reside. Because non-myogenic mesenchymal progenitors mainly undergo adipogenic or fibrogenic differentiation during muscle development, strengthening progenitor proliferation enhances the potential for both intramuscular adipogenesis and fibrogenesis, leading to the elevation of both marbling and connective tissue content in the resulting meat product. Furthermore, given the bipotent developmental potential of progenitor cells, enhancing their conversion to adipogenesis reduces fibrogenesis, which likely results in the overall improvement of marbling (more intramuscular adipocytes) and tenderness (less connective tissue) of meat. Fibrogenesis is mainly regulated by the transforming growth factor (TGF) β signaling pathway and its regulatory cascade. In addition, extracellular matrix, a part of the intramuscular connective tissue, provides a niche environment for regulating myogenic differentiation of satellite cells and muscle growth. Despite rapid progress, many questions remain in the role of extracellular matrix on muscle development, and factors determining the early differentiation of myogenic, adipogenic and fibrogenic cells, which warrant further studies.
We are undertaking an observational program using the ATCA to monitor the intraday variability (IDV) of a sample of sources at 4.8 and 8.6 GHz. The sources were selected to include the known strong southern IDV sources plus a number of sources whose IDV was recently discovered. The present monitoring program will extend over a full year in order to search for any annual cycle that may be present in the long-term IDV characteristics of these sources. In this paper we discuss the observing strategy and data analysis, and present the first results from our observations.
The future of centimetre and metre-wave astronomy lies with the Square Kilometre Array (SKA), a telescope under development by a consortium of 17 countries that will be 50 times more sensitive than any existing radio facility. Most of the key science for the SKA will be addressed through large-area imaging of the Universe at frequencies from a few hundred MHz to a few GHz. The Australian SKA Pathfinder (ASKAP) is a technology demonstrator aimed in the mid-frequency range, and achieves instantaneous wide-area imaging through the development and deployment of phased-array feed systems on parabolic reflectors. The large field-of-view makes ASKAP an unprecedented synoptic telescope that will make substantial advances in SKA key science. ASKAP will be located at the Murchison Radio Observatory in inland Western Australia, one of the most radio-quiet locations on the Earth and one of two sites selected by the international community as a potential location for the SKA. In this paper, we outline an ambitious science program for ASKAP, examining key science such as understanding the evolution, formation and population of galaxies including our own, understanding the magnetic Universe, revealing the transient radio sky and searching for gravitational waves.
We are developing a purely commensal survey experiment for fast (<5 s) transient radio sources. Short-timescale transients are associated with the most energetic and brightest single events in the Universe. Our objective is to cover the enormous volume of transients parameter space made available by ASKAP, with an unprecedented combination of sensitivity and field of view. Fast timescale transients open new vistas on the physics of high brightness temperature emission, extreme states of matter and the physics of strong gravitational fields. In addition, the detection of extragalactic objects affords us an entirely new and extremely sensitive probe on the huge reservoir of baryons present in the IGM. We outline here our approach to the considerable challenge involved in detecting fast transients, particularly the development of hardware fast enough to dedisperse and search the ASKAP data stream at or near real-time rates. Through CRAFT, ASKAP will provide the testbed of many of the key technologies and survey modes proposed for high time resolution science with the SKA.
The insulin-independent and combined effects of fatty acids (FA; linoleic and oleic acids) and insulin in modulating lipid accumulation and adipogenesis in 3T3-L1 cells was investigated using a novel protocol avoiding the effects of a complex hormone ‘induction’ mixture. 3T3-L1 cells were cultured in Dulbecco’s modified Eagle’s medium (DMEM) plus serum (control) or in DMEM plus either 0.3 mmol/l linoleic or oleic acids with 0.3 mmol/l FA-free bovine serum albumin in the presence or absence of insulin. Cells were cultured for 4 to 8 days and cell number, lipid accumulation, peroxisome proliferator-activated receptor-gamma (PPAR-γ) and glucose transporter 4 (GLUT-4) protein expression were determined. Cell number appeared to be decreased in comparison with control cultures. In both oleic acid and linoleic acid-treated cells, notably in the absence (and presence) of insulin, oil-red O stain-positive cells showed abundant lipid. The percentage of cells showing lipid accumulation was greater in FA-treated cultures compared with control cells grown in DMEM plus serum (P < 0.001). Treatment with both linoleic and oleic acid-containing media evoked higher levels of PPAR-γ than observed in control cultures (P < 0.05). GLUT-4 protein also increased in response to treatment with both linoleic and oleic acid-containing media (P < 0.001). Lipid accumulation in 3T3-L1 cells occurs in response to either oleic or linoleic acids independently of the presence of insulin. Both PPAR-γ and GLUT-4 protein expression were stimulated. Both proteins are considered markers of adipogenesis, and these observations suggest that these cells had entered the physiological state broadly accepted as differentiated. Furthermore, 3T3-L1 cells can be induced to accumulate lipid in a serum-free medium supplemented with FA, without the use of induction protocols using complex hormone mixtures. We have demonstrated a novel model for the study of lipid accumulation that will improve the understanding of adipogenesis in adipocyte lineage cells.
Approximation of real and complex numbers by rationals and algebraic numbers appeared first in papers by Dirichlet, Liouville and Hermite on Diophantine approximation and the theory of transcendental numbers. During the first three decades of the 20th century, E. Borel and A. Khintchine introduced the so-called metric (or measure theoretic) approach in which one considers approximation to any number which does not belong to an exceptional null set (i.e., a set of measure zero). Neglecting such exceptional sets can lead to strikingly simple and general theorems, such as Khintchine's theorem (see below). The exceptional sets can be analysed more deeply by using Hausdorff dimension, which can distinguish between different null sets.
This article gives an account of results, methods and ideas connected with Lebesgue measure and Hausdorff dimension of such exceptional sets. We will be concerned mainly with the lower bound of the Hausdorff dimension. Although determining the correct lower bound for the Hausdorff dimension of a set is often (though by no means always) harder than determining the correct upper bound, recent developments indicate that for many problems, the correct lower bound can be established using information associated with the upper bound. There are some exceptions to this principle. For example, convergence in the Khintchine–Groshev type theorem (for terminology see Bernik & Dodson 1999) for the parabola is related to the upper bound which was proved in Bernik (1979). Nevertheless the divergence case is still unsettled.
The functional relations between the coordinates of points on a manifold make the
study of Diophantine approximation on manifolds much harder than the classical
theory in which the variables are independent. Nevertheless there has been considerable
progress in the metric theory of Diophantine approximation on smooth manifolds.
To describe this, some notation and terminology are needed.
The conflict between independently published ages for the Mushandike Granite, Zimbabwe
(2.92 ± 0.17 Ga and 3.45 ± 0.13 Ga) has been resolved in favour of the older age by SHRIMP U–Pb
analyses of zircon. Two samples yield indistinguishable estimates of 3374 ± 7 and 3368 ± 11 Ma for the
crystallization age of the magma. Together with published data from elsewhere in southern Zimbabwe,
the results imply a widespread magmatic event at about 3.35 Ga. A single zircon core giving 3.46 Ga,
together with the granite's previously measured Nd model age, suggests that the Mushandike magma
could have incorporated remobilized basement similar to the c. 3.5 Ga Tokwe gneisses which crop out
30 km to the west. The published Rb–Sr and Pb–Pb datasets show evidence of late Archaean disturbance
of Sr and Pb isotope systematics. In the absence of exposed contacts between the Mushandike
granite and the neighbouring Mushandike stromatolitic limestone, the new U–Pb emplacement age
suggests that the limestone is unconformable on the granite.
A preliminary study was conducted to quantify the lipid produced by differentiated 3T3-L1 cells after incubation in Dulbecco’s Modified Eagle Medium (DMEM) containing 10% foetal bovine serum (FBS), supplemented with or without dimethyl-sulphoxide (DMSO; 9•6 g/l) and acetone (1•2 g/l). The two media treatments were applied to 3T3-L1 cells, plated at either 15K or 30K cells per well in 24-well plates. Cells were grown to confluence (96 h) and then treated with dexamethasone, methyl-isobutylxanthine and insulin for 48 h and later maintained in their respective media treatments for another 144 h. Cells from each treatment were recovered after two, 5-min incubations with trypsin, washed and resuspended in DMEM and counted on a haemocytometer. The lipid in the cells was extracted with hexane derivatized with tetramethyl-guanidine and analysed by gas chromatography. Final mean cell density was 6•8 (s.e. 0•18) ✕ 105 and 4•6 (s.e. 0•19) ✕ 105 when initially plated at 30K and 15K cells per well, respectively. Inclusion of DMSO and acetone in the medium did not affect final cell numbers. Plating density did not affect concentration of lipid (0•55 (s.e. 0•08) mg per 1 ✕ 105 cells) but inclusion of DMSO and acetone led to overall decreases in total lipid concentration. Results indicate that initial plating density influenced final cell number in treatment cultures, but that DMSO and acetone treatments only had an effect on final lipid concentration. Collectively, these data suggest that the application of treatments to cell cultures may be influenced by the carrier vehicle that the treatment is contained in and this should be considered when developing an in vitro system to evaluate growth and development of adipocytes.