79 research outputs found
The impact of a young radio galaxy: clues from the cosmic ray electron population
No full textIn the framework of hierarchical structure formation, active galactic nuclei (AGN) feedback shapes the galaxy luminosity function. Low luminosity, galaxy-scale double radio sources are ideal targets to investigate the interplay between AGN feedback and star formation. We use Very Large Array and BIMA millimetre-wave array observations to study the radio continuum emission of NGC 3801 between 1.4 and 112.4 GHz. We find a prominent spectral break at ~10 GHz, where the spectrum steepens as expected from cosmic ray electron (CRe) ageing. Using the equipartition magnetic field and fitting JP models locally, we create a spatially resolved map of the spectral age of the CRe population. The spectral age of τint = 2.0 ± 0.2 Myr agrees within a factor of 2 with the dynamical age of the expanding X-ray emitting shells. The spectral age varies only little across the lobes, requiring an effective mixing process of the CRe such as a convective backflow of magnetized plasma. The jet termination points have a slightly younger CRe spectral age, hinting at in situ CRe re-acceleration. Our findings support the scenario where the supersonically expanding radio lobes heat the interstellar medium (ISM) of NGC 3801 via shock waves, and, as their energy is comparable to the energy of the ISM, are clearly able to influence the galaxy's further evolution
Contributions of Joseph Hardcastle to accounting theory
No full textJoseph Hardcastle was one of the foremost authorities on subjects connected with the mathematics of finance and other topics in accounting in the late 19th and early 20th centuries. As a teacher, author, and leader in the profession, he figured prominently in the elevation of accountancy. Hardcastle is relatively unknown in the literature except for having the distinction of scoring the highest grades on the first CPA exam in New York in 1896. However, he was well respected during his time as one of the premier theorists in accounting and was awarded an honorary degree of Master of Letters by New York University. Because of his prolific writings, his teaching of future accountants, and his interactions with members of the Institute of Accounts, he had a strong impact on the science of accounts, the dominant accounting theory in the U.S. at the turn of the century
Contributions of Joseph Hardcastle to Accounting Theory
No full textJoseph Hardcastle was one of the foremost authorities on subjects connected with the mathematics of finance and other topics in accounting in the late 19th and early 20th centuries. As a teacher, author, and leader in the profession, he figured prominently in the elevation of accountancy. Hardcastle is relatively unknown in the literature except for having the distinction of scoring the highest grades on the first CPA exam in New York in 1896. However, he was well respected during his time as one of the premier theorists in accounting and was awarded an honorary degree of Master of Letters by New York University. Because of his prolific writings, his teaching of future accountants, and his interactions with members of the Institute of Accounts, he had a strong impact on the “science of accounts,” the dominant accounting theory in the U.S. at the turn of the century.</jats:p
Spectral ageing in the lobes of FR-II radio galaxies: new methods of analysis for broad-band radio data
No full textThe broad-bandwidth capabilities of next generation telescopes such as the Jansky Very Large Array (JVLA) mean that the spectrum of any given source varies significantly within the bandwidth of any given observation. Detailed spectral analysis taking this variation into account is set to become standard practice when dealing with any new broad-band radio observations; it is therefore vital that methods are developed to handle this new type of data. In this paper, we present the Broadband Radio Astronomy ToolS (brats) software package and, use it to carry out detailed analysis of JVLA observations of three powerful radio galaxies. We compare two of the most widely used models of spectral ageing, the Kardashev–Pacholczyk and Jaffe–Perola models and also results of the more complex, but potentially more realistic, Tribble model. We find that the Tribble model provides both a good fit to observations as well as providing a physically realistic description of the source. We present the first high-resolution spectral maps of our sources and find that the best-fitting injection indices across all models take higher values than have previously been assumed. We present characteristic hotspot advance speeds and make comparison to those derived from dynamical ages, confirming the previously known discrepancy in speed remains present when determined at high spectral resolutions. We show that some previously common assumptions made in determining spectral ages with narrow-band radio telescopes may not always hold and strongly suggest that these are accounted for in future investigations
Discovery of a single faint AGN in a large sample of z > 5 Lyman break galaxies
No full textAs part of a large spectroscopic survey of z > 5 Lyman break galaxies (LBGs), we have identified a single source which is clearly hosting an active galactic nucleus (AGN). Out of a sample of more than 50 spectroscopically confirmed R-band dropout galaxies at z∼ 5 and above, only J104048.6−115550.2 at z= 5.44 shows evidence for a high ionization potential emission line indicating the presence of a hard ionizing continuum from an AGN. Like most objects in our sample the rest-frame-UV spectrum shows the UV continuum breaking across a Lyα line. Uniquely within this sample of LBGs, emission from N V is also detected, a clear signature of AGN photoionization. The object is spatially resolved in Hubble Space Telescope (HST) imaging. This, and the comparatively high Lyα/N V flux ratio indicates that the majority of the Lyα (and the UV continuum longward of it) originates from stellar photoionization, a product of the ongoing starburst in the LBG. Even without the AGN emission, this object would have been photometrically selected and spectroscopically confirmed as a Lyman break in our survey. The measured optical flux (IAB= 26.1) is therefore an upper limit to that from the AGN and is of order 100 times fainter than the majority of known quasars at these redshifts. The detection of a single object in our survey volume is consistent with the best current models of high redshift AGN luminosity function, providing a substantial fraction of such AGN is found within luminous starbursting galaxies. We discuss the cosmological implications of this discovery
Mutations in CPAMD8 Cause a Unique Form of Autosomal-Recessive Anterior Segment Dysgenesis
No full textAnterior segment dysgeneses (ASDs) comprise a spectrum of developmental disorders affecting the anterior segment of the eye. Here, we describe three unrelated families affected by a previously unclassified form of ASD. Shared ocular manifestations include bilateral iris hypoplasia, ectopia lentis, corectopia, ectropion uveae, and cataracts. Whole-exome sequencing and targeted Sanger sequencing identified mutations in CPAMD8 (C3 and PZP-like alpha-2-macroglobulin domain-containing protein 8) as the cause of recessive ASD in all three families. A homozygous missense mutation in the evolutionarily conserved alpha-2-macroglobulin (A2M) domain of CPAMD8, c.4351T>C (p. Ser1451Pro), was identified in family 1. In family 2, compound heterozygous frameshift, c.2352_2353insC (p.Arg785Glnfs(∗)23), and splice-site, c.4549-1G>A, mutations were identified. Two affected siblings in the third family were compound heterozygous for splice-site mutations c.700+1G>T and c.4002+1G>A. CPAMD8 splice-site mutations caused aberrant pre-mRNA splicing in vivo or in vitro. Intriguingly, our phylogenetic analysis revealed rodent lineage-specific CPAMD8 deletion, precluding a developmental expression study in mice. We therefore investigated the spatiotemporal expression of CPAMD8 in the developing human eye. RT-PCR and in situ hybridization revealed CPAMD8 expression in the lens, iris, cornea, and retina early in development, including strong expression in the distal tips of the retinal neuroepithelium that form the iris and ciliary body, thus correlating CPAMD8 expression with the affected tissues. Our study delineates a unique form of recessive ASD and defines a role for CPAMD8, a protein of unknown function, in anterior segment development, implying another pathway for the pathogenicity of ASD
Osteophytes, enthesophytes and high bone mass: a bone-forming triad with potential relevance in osteoarthritis
No full textOBJECTIVE: Previous studies of skeletal remains have suggested that both enthesophytes and osteophytes are manifestations of an underlying bone-forming tendency. A greater prevalence of osteophytes has been observed among individuals with high bone mass (HBM) compared with controls. This study was undertaken to examine the possible interrelationships between bone mass, enthesophytes, and osteophytes in a population of individuals with extreme HBM.METHODS: Cases of HBM (defined according to bone mineral density [BMD] Z scores on dual x-ray absorptiometry) from the UK-based HBM study were compared with a control group comprising unaffected family members and general population controls from the Chingford and Hertfordshire cohort studies. Pelvic radiographs from cases and controls were pooled and evaluated, in a blinded manner, by a single observer, who performed semiquantitative grading of the radiographs for the presence and severity of osteophytes and enthesophytes (score range 0-3 for each). Logistic regression analysis was used to identify significant associations, with a priori adjustment for age, sex, and body mass index.RESULTS: In this study, 226 radiographs from HBM cases and 437 radiographs from control subjects were included. Enthesophytes (grade ?1) and moderate enthesophytes (grade ?2) were more prevalent in HBM cases compared with controls (adjusted odds ratio [OR] 3.00 [95% confidence interval (95% CI) 1.96-4.58], P < 0.001 for any enthesophyte; adjusted OR 4.33 [95% CI 2.67-7.02], P < 0.001 for moderate enthesophytes). In the combined population of cases and controls, the enthesophyte grade was positively associated with BMD at both the total hip and lumbar spine (adjusted P for trend < 0.001). In addition, a positive association between osteophytes and enthesophytes was observed; for each unit increase in enthesophyte grade, the odds of any osteophyte being present were increased >2-fold (P < 0.001).CONCLUSION: Strong interrelationships were observed between osteophytes, enthesophytes, and HBM, which may be helpful in defining a distinct subset of patients with osteoarthritis characterized by excess bone formation
The star formation rate of the Universe atz≈ 6 from the Hubble ultra-Deep Field
No full textWe determine the abundance of i′-band dropouts in the recently released HST/ACS Hubble Ultra-Deep Field (UDF). Because the majority of these sources are likely to be z≈ 6 galaxies whose flux decrement between the F775W i′-band and F850LP z′-band arises from Lyman-α absorption, the number of detected candidates provides a valuable upper limit to the unextincted star formation rate at this redshift. We demonstrate that the increased depth of UDF enables us to reach an 8 σ limiting magnitude of z′AB= 28.5 (equivalent to 1.5 h−270 M⊙ yr−1 at z= 6.1, or 0.1 L⋆UV for the z≈ 3U-drop population), permitting us to address earlier ambiguities arising from the unobserved form of the luminosity function. We identify 54 galaxies (and only one star) at z′AB 1.3 over the deepest 11-arcmin2 portion of the UDF. The characteristic luminosity (L⋆) is consistent with values observed at z≈ 3. The faint end slope (α) is less well constrained, but is consistent with only modest evolution. The main change appears to be in the number density (Φ*). Specifically, and regardless of possible contamination from cool stars and lower-redshift sources, the UDF data support our previous result that the star formation rate at z≈ 6 was approximately six times less than at z≈ 3. This declining comoving star formation rate [0.005 h70 M⊙ yr−1 Mpc−3 at z≈ 6 at LUV > 0.1 L⋆ for a Salpeter initial mass function (IMF)] poses an interesting challenge for models which suggest that LUV > 0.1 L⋆ star-forming galaxies at z≃ 6 reionized the Universe. The short-fall in ionizing photons might be alleviated by galaxies fainter than our limit, or a radically different IMF. Alternatively, the bulk of reionization might have occurred at z≫ 6
The creation of Yorkshireness: Cultural identities in Yorkshire c.1850-1918
No full textTHE rapid expansion, wider distribution and increased readership of print media in the latter half of the nineteenth century helped to foster the process that has been described as the nationalisation of English culture. In a parallel process, however, the same media could also be deployed to construct and to propagate regional cultures and identities. This thesis, concentrating on the period c.1850-1918, uses Yorkshire as a case study. The employment of county boundaries and structures as a delimitation for historical research can be questioned. But it is defensible in the case of the cultural study of a county that, in spite of its size, heterogeneity and industrial transformation, had acquired a set of identities and stereotypes which evolved during the early-modern period and were retained, refined and celebrated in the industrial age. Although it had no political basis, Yorkshireness remained a powerful sub-identity within England, the United Kingdom and the wider British world.
By examining the newspaper press, weekly periodicals, dialect almanacs and regional fiction, the thesis explores the evolution and the dissemination of Yorkshire’s cultural identity in an age of popular print. There is also an analysis of attempts to find a deterministic basis for Yorkshire character and a description of county societies in the UK and overseas. The evolution of folkloristic Yorkshire identities and symbols is traced, and illustrated dialect postcards of the early-twentieth century are analysed, on the grounds that they were a widely-transmitted source of Yorkshire stereotypes.
Individuals who played a role in the construction of Yorkshireness include the writer James Burnley, the folklorist and humorist Richard Blakeborough, the novelists Halliwell Sutcliffe and William Riley, the dialect writers Charles Rogers and John Hartley, the cartoonist Arthur North and the University of Leeds academic Professor Frederic Moorman, who conceived the project for eisteddfod equivalents in Yorkshire. The conclusion is that Victorian and Edwardian print media and illustrated ephemera were used extensively to construct and convey a sense of Yorkshireness, acting as a countervailing force to the tendency towards nationalisation of culture, and that in the absence of a fully negotiated concept of universal Englishness, county identity was an important factor at home and overseas
RANGELAND FIRES IN NORTHERN NEVADA: AN APPLICATION OF COMPUTABLE GENERAL EQUILIBRIUM MODELING
No full textResource /Energy Economics and Policy,
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