Primary cancer of the liver in Kenyan children.

In 9 years in Kenya, 34 examples of primary liver cancer wer diagnosed in patients in the first two decades of life. This represents 4.7% of all liver cancers during this period. The larger proportion (29) were hepatocellular carcinoma. In the second decade, there was a notable association with macronodular cirrhosis. Analogy with experimental work suggests that cells in mitotic cycle may be more vulnerable to the effect of environmental carcinogens. Five examples of hepatoblastoma were identified at ages from 2 months to 14 years; none showed the features of "mixed" tumours. The ratio of hepatoblastoma to hepatocellular carcinoma was the reverse of that found in other large series of juvenile hepatic tumours. The histopathological features of these tumours are described and problems of their classification are discussed

Passing the Turing Test Does Not Mean the End of Humanity

In this paper we look at the phenomenon that is the Turing test. We consider how Turing originally introduced his imitation game and discuss what this means in a practical scenario. Due to its popular appeal we also look into different representations of the test as indicated by numerous reviewers. The main emphasis here, however, is to consider what it actually means for a machine to pass the Turing test and what importance this has, if any. In particular does it mean that, as Turing put it, a machine can “think”. Specifically we consider claims that passing the Turing test means that machines will have achieved human-like intelligence and as a consequence the singularity will be upon us in the blink of an eye

“More than scaling up”: a critical and practical inquiry into operationalizing sustainability competencies

This chapter starts from the UN Decade of Education for Sustainable Development (DESD) Final Report’s call that in Higher Education, ‘more than scaling up of good practice’ and ‘greater attention to systemic approaches to curriculum change and capacity building for leaders will be needed’ (UNESCO 2014a, p. 31). It recognises this need and the additional, rather profound reform and transformation of educational policy and practice that is required to meet the heightened expectations of education in an increasingly volatile, conflict laden, and challenging world. The emphasis is on clarification and framing of work to date and identification of relevant research gaps. In particular, it addresses the current status of the literature on competencies in ESD, which is characterised by a sea of labels, terminological confusion, and relative inattention to pedaogogic implications. The research outlined is both a critical inquiry into the status of work to date on sustainability competencies and a practical inquiry into the possibility of innovative and transformative institutional strategies and pedagogies around a suite of specific competencies. To this end, the early stages of an international and cross-institutional pilot project collaboration designed to help realize the UN’s ambitious Sustainable Development Goals (SDGs) and UNESCO’s Global Action Plan (GAP) (UNESCO 2014b), is described briefl

X 1908+075: An X-ray Binary with a 4.4 day Period

X 1908+075 is an optically unidentified and highly absorbed X-ray source that appears in early surveys such as Uhuru, OSO-7, Ariel V, HEAO-1, and the EXOSAT Galactic Plane Survey. These surveys measured a source intensity in the range of 2-12 mCrab at 2-10 keV, and the position was localized to ~ 0.5 degrees. We use the Rossi X-ray Timing Explorer (RXTE) All Sky Monitor (ASM) to confirm our expectation that a particular Einstein IPC detection (1E 1908.4+0730) provides the correct position for X 1908+075. The analysis of the coded mask shadows from the ASM for the position of 1E 1908.4+0730 yields a persistent intensity ~ 8 mCrab (1.5-12 keV) over a 3 year interval beginning in 1996 February. Furthermore, we detect a period of 4.400 +- 0.001 days with a false alarm probability < 1.0e-7 . The folded light curve is roughly sinusoidal, with an amplitude that is 22 % of the mean flux. The X-ray period may be attributed to the scattering and absorption of X-rays through a stellar wind combined with the orbital motion in a binary system. We suggest that X 1908+075 is an X-ray binary with a high mass companion star.Comment: 6 pages, two-column,"emulateapj" style, submitted to Ap

X-ray Spectroscopy of Candidate Ultracompact X-ray Binaries

We present high-resolution spectroscopy of the neutron star/low-mass X-ray binaries (LMXBs) 4U 1850-087 and 4U 0513-40 as part of our continuing study of known and candidate ultracompact binaries. The LMXB 4U 1850-087 is one of four systems in which we had previously inferred an unusual Ne/O ratio in the absorption along the line of sight, most likely from material local to the binaries. However, our recent Chandra X-ray Observatory LETGS spectrum of 4U 1850-087 finds a Ne/O ratio by number of 0.22+/-0.05, smaller than previously measured and consistent with the expected interstellar value. We propose that variations in the Ne/O ratio due to source variability, as previously observed in these sources, can explain the difference between the low- and high-resolution spectral results for 4U 1850-087. Our XMM-Newton RGS observation of 4U 0513-40 also shows no unusual abundance ratios in the absorption along the line of sight. We also present spectral results from a third candidate ultracompact binary, 4U 1822-000, whose spectrum is well fit by an absorbed power-law + blackbody model with absorption consistent with the expected interstellar value. Finally, we present the non-detection of a fourth candidate ultracompact binary, 4U 1905+000, with an upper limit on the source luminosity of < 1 x 10^{32} erg s^{-1}. Using archival data, we show that the source has entered an extended quiescent state.Comment: 8 pages, 3 figures, accepted for publication to the Astrophysical Journa

BeppoSAX Observations of the Maser Sy2 Galaxy: ESO103-G35

We have made BeppoSAX observations of the Seyfert 2/1.9 galaxy ESO103-G35, which contains a nuclear maser source and is known to be heavily absorbed in the X-rays. Analysis of the X-ray spectra observed by SAX in October 1996 and 1997 yields a spectral index 0.74+/-0.07, typical of Seyfert galaxies and consistent with earlier observations of this source. The strong, soft X-ray absorption has column density 1.79E(23)/cm^2, again consistent with earlier results. The best fitting spectrum is that of a power law with a high energy cutoff at 29+/-10 keV, a cold, marginally resolved Fe Kalpha line with EW 290 eV (1996) and a mildly ionized Fe K-edge at 7.37 keV. The Kalpha line and cold absorption are consistent with origin in a accretion disk/torus through which our line-of-sight passes at a radial distance of $\sim 50$ pc. The Fe K-edge is mildly ionized suggesting the presence of ionized gas probably in the inner accretion disk, close to the central source or in a separate warm absorber. The data quality is too low to distinguish between these possibilities but the edge-on geometry implied by the water maser emission favors the former. Comparison with earlier observations of ESO103-G35 shows little/no change in spectral parameters while the flux changes by factors of a few on timescales of a few months. The 2--10 keV flux decreased by a factor of 2.7 between Oct 1996 and Oct 1997 with no detectable change in the count rate >20 keV suggesting a constant or delayed response reflection component. The high energy cutoff is lower than the typical 300keV values seen in Seyfert galaxies. A significant subset of similar sources would affect current models of the AGN contribution to the cosmic X-ray background which generally assume a high energy cutoff of 300 keV.Comment: 22 pages, postscript file, accepted for publication in Ap

‘More than scaling-up’: Sustainability contexts, competencies, and consequences - a critical inquiry

To identify and problematise the key issues characterising the relationship between global sustainability contexts and the limited response of HE to date - with the purpose of unlocking the potential for innovative, replicable efforts to develop sustainability competencies through innovation in curriculum policy and practice, through addressing these sub-aims: How far does HE policy accommodate and reflect the need for sustainability competencies? How can capacity for teaching for competency be built and supported through new policies? How can curricula and pedagogy be better aligned to facilitate the building of sustainability competency in learners and teachers? What effect and influence does education for sustainability competency have in terms of facilitating transformative social learning, supporting systems structure change, and cultivating informed responsibility (in terms of policy and everyday decision making)?PedRI

Revealing ensemble state transition patterns in multi-electrode neuronal recordings using hidden Markov models

In order to harness the computational capacity of dissociated cultured neuronal networks, it is necessary to understand neuronal dynamics and connectivity on a mesoscopic scale. To this end, this paper uncovers dynamic spatiotemporal patterns emerging from electrically stimulated neuronal cultures using hidden Markov models (HMMs) to characterize multi-channel spike trains as a progression of patterns of underlying states of neuronal activity. However, experimentation aimed at optimal choice of parameters for such models is essential and results are reported in detail. Results derived from ensemble neuronal data revealed highly repeatable patterns of state transitions in the order of milliseconds in response to probing stimuli

Variable X-ray Absorption in the Seyfert 2 Galaxy Mrk 348

We present RXTE monitoring observations of the Seyfert 2 galaxy Mrk 348 spanning a 6 month period. The time-averaged spectrum in the 3-20 keV band shows many features characteristic of a Compton-thin Seyfert 2 galaxy, namely a hard underlying power-law continuum (photon index = 1.8) with heavy soft X-ray absorption (N_h ~ 10^23 cm^-2) plus measureable iron line emission (equivalent width ~ 100 eV) and, at high energy, evidence for a reflection component (R < 1). During the first half of the monitoring period the X-ray continuum flux from Mrk 348 remained relatively steady. However this was followed by a significant brightening of the source (by roughly a factor of 4) with the fastest change corresponding to a doubling of its X-ray flux on a timescale of about 20 days. The flux increase was accompanied by a marked softening of X-ray spectrum most likely attributable to a factor 3 decline in the intrinsic line-of-sight column density. In contrast the iron line and the reflection components showed no evidence of variability. These observations suggest a scenario in which the central X-ray source is surrounded by a patchy distribution of absorbing material located within about a light-week of the nucleus of Mrk 348. The random movement of individual clouds within the absorbing screen, across our line of sight, produces substantial temporal variations in the measured column density on timescales of weeks to months and gives rise to the observed X-ray spectral variability. However, as viewed from the nucleus the global coverage and typical thickness of the cloud layer remains relatively constant.Comment: 19 pages, 3 figures Accepted for publication in the Astrophysical Journa