172 research outputs found
BMP signals: Mediated by stroma or thymocytes?
This is an invited comment on the paper by Hager-Theodorides AL, et al. Cell Cycle 2014; 13:324–33; PMID:24240189; http://dx.doi.org/10.4161/cc.27118 which is published in the same journa
Probing 3-D matter distribution at z~2 with QSO multiple lines of sight
We investigate the 3-D matter distribution at z~2 with high resolution (R ~
40000) spectra of QSO pairs and groups obtained with the UVES spectrograph at
ESO VLT. Our sample is unique for the number density of objects and the variety
of separations, between 0.5 and 7 proper Mpc. We compute the real space
cross-correlation function of the Lyman-alpha forest transmitted fluxes. There
is a significant clustering signal up to ~2 proper Mpc, which is still present
when absorption lines with high column density (log N > 13.8) are excluded.Comment: Poster paper presented at the IAU Colloquium #199 on "Probing
Galaxies through Quasar Absorption Lines" held in Shanghai, China from March
14th to 18th, 200
Tomography of the intergalactic medium with Ly-alpha forests in close QSO pairs
We study the three-dimensional distribution of non virialised matter at z~2
using high resolution spectra of QSO pairs and simulated spectra drawn from
cosmological hydrodynamical simulations. We have collected the largest sample
of QSO pairs ever observed with UVES at the ESO-VLT, with angular separations
between ~1 and 14 arcmin. The observed correlation functions of the transmitted
flux in the HI Lyman alpha forest along and transverse to the lines of sight
are in good agreement implying that the distortions in redshift space due to
peculiar velocities are small. The clustering signal is significant up to
velocity separations of ~200 km/s, or about 3 h^{-1} comoving Mpc. The regions
at lower overdensity (rho/ < 6.5) are still clustered but on smaller
scales (Delta v < 100 km/s). The observed and simulated correlation functions
are compatible at the 3 sigma level. A better concordance is obtained when only
the low overdensity regions are selected for the analysis or when the effective
optical depth of the simulated spectra is increased artificially, suggesting a
deficiency of strong lines in the simulated spectra. We found that also a lower
value of the power-law index of the temperature-density relation for the Lyman
alpha forest gas improves the agreement between observed and simulated results.
If confirmed, this would be consistent with other observations favouring a late
HeII reionization epoch (at z~3). We remark the detection of a significant
clustering signal in the cross correlation coefficient at a transverse velocity
separation Delta v_{\perp} ~500 km/s whose origin needs further investigation.Comment: Accepted for publication in MNRAS, revised version matching the
accepted on
A new zooarchaeological application for geometric morphometric methods: Distinguishing Ovis aries morphotypes to address connectivity and mobility of prehistoric Central Asian pastoralists.
This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.Geometric morphometric methods (GMM), which were developed to characterize the shape and size of biological organisms, have been applied within zooarchaeology over the past decade to address animal domestication processes and to refine morphological criteria to differentiate between taxa. However, there has been limited utilization of these methods to discriminate between populations of the same taxa to challenge and refine other key archaeological issues, such as migration and connectivity in prehistory. Presented here is a novel application of a three-dimensional landmark based geometric morphometric approach to address the nature of long distance trade and connectivity on the prehistoric Silk Road. The similarity of Bronze and Iron Age archaeological cultures along this steppe route has encouraged characterisations of these people as nomads, with highly mobile, integrated, and connected human and animal populations. However, the interconnectedness of domestic animal populations, in particular sheep (Ovis aries), the foundation of this prehistoric pastoral economy, has never been examined. This study utilized geometric morphometric methods to quantify geometric morphometric variance of O. aries astragali between three geographically disparate settlement sites within a single Final Bronze age cultural and chronological context. Significant differences between morphotypes revealed that protracted mobility patterns were unlikely and that while animal exchange may have occurred, it was not pervasive enough to produce a uniform sheep morphotype across central and southeastern Kazakhstan. The result of this new application of geometric morphometric methods challenges models of uniform and undifferentiated long distance mobility and economic connectivity between the peoples of the Silk Road.Fulbright scholarshipFrances Mary Hazen fellowshi
Archaeological supplement B to Damgaard et al. 2018: discussion of the archaeology of Central Asian and East Asian Neolithic to Bronze Age hunter-gatherers and early pastoralists, including consideration of horse domestication
This is the author accepted manuscript. The final version is available from Zenodo via the DOI in this recordThis is part of the additional supplementary material for Damgaard et al., The first horse herders and the impact of early Bronze Age steppe expansions into Asia. Science. DOI: 10.1126/science.aar7711. Note that the author accepted manuscript version of the article plus supplementary material and additional supplementary material is in ORE at http://hdl.handle.net/10871/32791The archaeological evidence relating to selected key cultures from Central and East Asia from the
Neolithic to the Bronze Age is summarized. These cultures include the Eneolithic (Copper Age)
Botai culture of northern Kazakhstan, the Bronze Age Okunevo culture from the Minusinsk Basin
in Russia and Neolithic to Bronze Age cultures of the Baikal Region in East Siberia. Special
consideration is given to the debate surrounding horse domestication within the Botai Culture, and
the key lines of evidence are summarized
Correlation function of quasars in real and redshift space from the Sloan Digital Sky Survey Data Release 7
We analyze the quasar two-point correlation function (2pCF) within the
redshift interval using a sample of 52303 quasars selected from the
recent 7th Data Release of the Sloan Digital Sky Survey. Our approach to 2pCF
uses a concept of locally Lorentz (Fermi) frame for determination of the
distance between objects and permutation method of the random catalogue
generation. Assuming the spatially flat cosmological model with given
, we found that the real-space 2pCF is fitted well with
the power-low model within the distance range Mpc with
the correlation length Mpc and the slope
. The redshift-space 2pCF is approximated with
Mpc and for
Mpc, and Mpc and for
Mpc the parameter
describing the large-scale infall to density inhomogeneities is
with the linear bias that marginally
(within 2) agrees with the linear theory of cosmological perturbations.
We discuss possibilities to obtain a statistical estimate of the random
component of quasars velocities (different from the large-scale infall). We
note rather slight dependence of quasars velocity dispersion upon the 2pCF
parameters in the region Mpc.Comment: 15 pages, 17 figures, online published in MNRAS; final version to
match the published versio
Repression of hedgehog signal transduction in T-lineage cells increases TCR-induced activation and proliferation
Hedgehog proteins signal for differentiation, survival and proliferation of the earliest thymocyte progenitors, but their functions at later stages of thymocyte development and in peripheral T-cell function are controversial. Here we show that repression of Hedgehog (Hh) pathway activation in T-lineage cells, by expression of a transgenic repressor form of Gli2 (Gli2DeltaC2), increased T-cell differentiation and activationin response to TCR signalling. Expression of the Gli2DeltaC2 transgene increased differentiation from CD4(+)CD8(+) to single positive thymocyte, and increased peripheral T cell populations. Gli2DeltaC2 T-cells were hyper-responsive to activation by ligation of CD3 and CD28: they expressed cell surface activation markers CD69 and CD25 more quickly, and proliferated more than wild-type T-cells. These data show that Hedgehog pathway activation in thymocytes and T-cells negatively regulates TCR-dependent differentiation and proliferation. Thus, as negative regulators of TCR-dependent events, Hh proteins provide an environmental influence on T-cell fate
Further Evidence for Cosmological Evolution of the Fine Structure Constant
We describe the results of a search for time variability of the fine
structure constant, alpha, using absorption systems in the spectra of distant
quasars. Three large optical datasets and two 21cm/mm absorption systems
provide four independent samples, spanning 23% to 87% of the age of the
universe. Each sample yields a smaller alpha in the past and the optical sample
shows a 4-sigma deviation: da/a = -0.72 +/- 0.18 x 10^{-5} over the redshift
range 0.5 < z < 3.5. We find no systematic effects which can explain our
results. The only potentially significant systematic effects push da/a towards
positive values, i.e. our results would become more significant were we to
correct for them.Comment: 5 pages, 1 figure. Published in Phys. Rev. Lett. Small changes to
discussion, added an acknowledgement and a referenc
Inventing the Neolithic? Putting evidence-based interpretation back into the study of faunal remains from causewayed enclosures.
ArticleThis is an Accepted Manuscript of an article published by Taylor & Francis in World Archaeology on 2015, available online: http://wwww.tandfonline.com/10.1080/00438243.2015.1072476The paper argues that our current understanding of the animal bones from causewayed enclosure sites in Britain is flawed. During the 1980-90s, a number of key interpretations, still frequently espoused, were based more upon anecdote and theory-driven assertion than on empirical evidence. An example is that evidence of bone processing (butchery and bone fracture) does not feature heavily in the faunal record from causewayed enclosures. Using data from the sites of Etton and Staines, this view must now be questioned. Both butchery and peri-mortem bone fracture are present in these assemblages in substantial quantities. These sites are compared with Ludwinowo 7, a Linearbandkeramik settlement site in Poland and there are considerable similarities between the three different sites. This suggests possibility that the broader economic utility of animal bone assemblages at causewayed enclosures has been underestimated, having been, up to now, regarded as ‘not indicative of domestic settlement’
- …