A Reference Section for the Otavi Group (Damara Supergroup) in Eastern Kaoko Zone near Ongongo, Namibia

A reference section for the Otavi Group (Damara Supergroup) in the East Kaoko Zone near Ongongo is proposed and described. The section is easily accessible, well exposed, suitable for field excursions, and well documented in terms of carbonate lithofacies, depositional sequences and stableisotope chemostratigraphy. The late Tonian Ombombo Subgroup is 355 m thick above the basal Beesvlakte Formation, which is not included in the section due to poor outcrop and complex structure. The earlymiddle Cryogenian Abenab Subgroup is 636 m thick and the early Ediacaran Tsumeb Subgroup is 1020 m thick. While the section is complete in terms of formations represented, the Ombombo and lower Abenab subgroups have defined gaps due to intermittent uplift of the northward-sloping Makalani rift shoulder. The upper Abenab and Tsumeb subgroups are relatively thin due to erosion of a broad shallow trough during late Cryogenian glaciation and flexural arching during post-rift thermal subsidence of the carbonate platform

West Nile Virus Viremia in Wild Rock Pigeons

Feral rock pigeons were screened for neutralizing antibodies to West Nile virus (WNV) during late winter/spring and summer of 2002 and 2003. Additionally, virus isolation from serum was attempted from 269 birds collected during peak transmission periods. The observed viremia levels and seroprevalence indicate that this species could be involved in amplifying WNV in urban settings

Earliest hominin cancer: 1.7-million-year- old osteosarcoma from Swartkrans Cave, South Africa

The reported incidence of neoplasia in the extinct human lineage is rare, with only a few confirmed cases of Middle or Later Pleistocene dates reported. It has generally been assumed that premodern incidence of neoplastic disease of any kind is rare and limited to benign conditions, but new fossil evidence suggests otherwise. We here present the earliest identifiable case of malignant neoplastic disease from an early human ancestor dated to 1.8–1.6 million years old. The diagnosis has been made possible only by advances in 3D imaging methods as diagnostic aids. We present a case report based on re-analysis of a hominin metatarsal specimen (SK 7923) from the cave site of Swartkrans in the Cradle of Humankind, South Africa. The expression of malignant osteosarcoma in the Swartkrans specimen indicates that whilst the upsurge in malignancy incidence is correlated with modern lifestyles, there is no reason to suspect that primary bone tumours would have been any less frequent in ancient specimens. Such tumours are not related to lifestyle and often occur in younger individuals. As such, malignancy has a considerable antiquity in the fossil record, as evidenced by this specimen.NCS201

Statistics of Atmospheric Correlations

For a large class of quantum systems the statistical properties of their spectrum show remarkable agreement with random matrix predictions. Recent advances show that the scope of random matrix theory is much wider. In this work, we show that the random matrix approach can be beneficially applied to a completely different classical domain, namely, to the empirical correlation matrices obtained from the analysis of the basic atmospheric parameters that characterise the state of atmosphere. We show that the spectrum of atmospheric correlation matrices satisfy the random matrix prescription. In particular, the eigenmodes of the atmospheric empirical correlation matrices that have physical significance are marked by deviations from the eigenvector distribution.Comment: 8 pages, 9 figs, revtex; To appear in Phys. Rev.

Monte Carlo reconstruction of the inflationary potential

We present Monte Carlo reconstruction, a new method for ``inverting'' observational data to constrain the form of the scalar field potential responsible for inflation. This stochastic technique is based on the flow equation formalism and has distinct advantages over reconstruction methods based on a Taylor expansion of the potential. The primary ansatz required for Monte Carlo reconstruction is simply that inflation is driven by a single scalar field. We also require a very mild slow roll constraint, which can be made arbitrarily weak since Monte Carlo reconstruction is implemented at arbitrary order in the slow roll expansion. While our method cannot evade fundamental limits on the accuracy of reconstruction, it can be simply and consistently applied to poor data sets, and it takes advantage of the attractor properties of single-field inflation models to constrain the potential outside the small region directly probed by observations. We show examples of Monte Carlo reconstruction for data sets similar to that expected from the Planck satellite, and for a hypothetical measurement with a factor of five better parameter discrimination than Planck.Comment: 10 pages, 5 figures (RevTeX 4) Version submitted to PRD: references added, minor clarification

Inflation with a constant ratio of scalar and tensor perturbation amplitudes

The single scalar field inflationary models that lead to scalar and tensor perturbation spectra with amplitudes varying in direct proportion to one another are reconstructed by solving the Stewart-Lyth inverse problem to next-to-leading order in the slow-roll approximation. The potentials asymptote at high energies to an exponential form, corresponding to power law inflation, but diverge from this model at low energies, indicating that power law inflation is a repellor in this case. This feature implies that a fine-tuning of initial conditions is required if such models are to reproduce the observations. The required initial conditions might be set through the eternal inflation mechanism. If this is the case, it will imply that the spectral indices must be nearly constant, making the underlying model observationally indistinguishable from power law inflation.Comment: 20 pages, 7 figures. Major changes to the Introduction following referee's comments. One figure added. Some other minor changes. No conclusion was modifie

A Measurement of Time-Averaged Aerosol Optical Depth using Air-Showers Observed in Stereo by HiRes

Air fluorescence measurements of cosmic ray energy must be corrected for attenuation of the atmosphere. In this paper we show that the air-showers themselves can yield a measurement of the aerosol attenuation in terms of optical depth, time-averaged over extended periods. Although the technique lacks statistical power to make the critical hourly measurements that only specialized active instruments can achieve, we note the technique does not depend on absolute calibration of the detector hardware, and requires no additional equipment beyond the fluorescence detectors that observe the air showers. This paper describes the technique, and presents results based on analysis of 1258 air-showers observed in stereo by the High Resolution Fly's Eye over a four year span.Comment: 7 pages, 3 figures, accepted for publication by Astroparticle Physics Journa

"Dark energy" in the Local Void

The unexpected discovery of the accelerated cosmic expansion in 1998 has filled the Universe with the embarrassing presence of an unidentified "dark energy", or cosmological constant, devoid of any physical meaning. While this standard cosmology seems to work well at the global level, improved knowledge of the kinematics and other properties of our extragalactic neighborhood indicates the need for a better theory. We investigate whether the recently suggested repulsive-gravity scenario can account for some of the features that are unexplained by the standard model. Through simple dynamical considerations, we find that the Local Void could host an amount of antimatter ($\sim5\times10^{15}\,M_\odot$) roughly equivalent to the mass of a typical supercluster, thus restoring the matter-antimatter symmetry. The antigravity field produced by this "dark repulsor" can explain the anomalous motion of the Local Sheet away from the Local Void, as well as several other properties of nearby galaxies that seem to require void evacuation and structure formation much faster than expected from the standard model. At the global cosmological level, gravitational repulsion from antimatter hidden in voids can provide more than enough potential energy to drive both the cosmic expansion and its acceleration, with no need for an initial "explosion" and dark energy. Moreover, the discrete distribution of these dark repulsors, in contrast to the uniformly permeating dark energy, can also explain dark flows and other recently observed excessive inhomogeneities and anisotropies of the Universe.Comment: 6 pages, accepted as a Letter to the Editor by Astrophysics and Space Scienc

Genomic epidemiology of escherichia coli isolates from a tertiary referral center in lilongwe, Malawi

Antimicrobial resistance (AMR) is a global threat, including in sub-Saharan Africa. However, little is known about the genetics of resistant bacteria in the region. In Malawi, there is growing concern about increasing rates of antimicrobial resistance to most empirically used antimicrobials. The highly drug resistant Escherichia coli sequence type (ST) 131, which is associated with the extended spectrum β-lactamase blaCTX-M-15, has been increasing in prevalence globally. Previous data from isolates collected between 2006 and 2013 in southern Malawi have revealed the presence of ST131 and the blaCTX-M-15 gene in the country. We performed whole genome sequencing (WGS) of 58 clinical E. coli isolates at Kamuzu Central Hospital, a tertiary care centre in central Malawi, collected from 2012 to 2018. We used Oxford Nanopore Technologies (ONT) sequencing, which was performed in Malawi. We show that ST131 is observed more often (14.9% increasing to 32.8%) and that the blaCTX-M-15 gene is occurring at a higher frequency (21.3% increasing to 44.8%). Phylogenetics indicates that isolates are highly related between the central and southern geographic regions and confirms that ST131 isolates are contained in a single group. All AMR genes, including blaCTX-M-15, were widely distributed across sequence types. We also identified an increased number of ST410 isolates, which in this study tend to carry a plasmid-located copy of blaCTX-M-15 gene at a higher frequency than blaCTX-M-15 occurs in ST131. This study confirms the expanding nature of ST131 and the wide distribution of the blaCTX-M-15 gene in Malawi. We also highlight the feasibility of conducting longitudinal genomic epidemiology studies of important bacteria with the sequencing done on site using a nanopore platform that requires minimal infrastructure

Inflation: flow, fixed points and observables to arbitrary order in slow roll

I generalize the inflationary flow equations of Hoffman and Turner to arbitrary order in slow roll. This makes it possible to study the predictions of slow roll inflation in the full observable parameter space of tensor/scalar ratio $r$, spectral index $n$, and running $d n / d \ln k$. It also becomes possible to identify exact fixed points in the parameter flow. I numerically evaluate the flow equations to fifth order in slow roll for a set of randomly chosen initial conditions and find that the models cluster strongly in the observable parameter space, indicating a ``generic'' set of predictions for slow roll inflation. I comment briefly on the the interesting proposed correspondence between flow in inflationary parameter space and renormalization group flow in a boundary conformal field theory.Comment: 16 pages, 7 figures. LaTeX. V4: Fixed important error in numerical constant in the second-order slow roll expressions for the observables r, n, and dn/dlog(k). See footnote after Eq. (48). New figures, minor changes to conclusions. Supersedes version published in Phys. Rev.