3,789 research outputs found
Fashion in the grave : A study of the motifs used to decorate the grave altars, ash chests and sarcophag made in rome in the early empire (To the mid second century A.D.).
The purpose of this study is to explain why cremation was replaced
by inhumation and cinerary monuments by sarcophagi in Rome
during the second century A.D. by looking at the decoration of the
monuments from Tiberius to the mid second century.Part one examines
briefly the treatment of Boman funerary symbolism by previous scholars,
the literary and epigraphic evidence for Roman eschatological belief
In the period, and the nature of the contemporary decorative repertoire
used in non—funerary contexts. These studies suggest that Roman
eschatological ideas were somewhat vague, and that most of the motifs
used on the funerary monuments were in common use in other decorative
arts: one should not, therefore, expect the decoration of the
funerary monuments to contain allusions to a deep or coherent
eschatology. The final chapter of Part one deals with the evidence
for the chronology of the monuments. Part two looks at the decoration
of the cinerary monuments motif by motif, considering in particular
their possible symbolic interpretations. The conclusion is that
there is little evidence to suggest that this decoration was designed
to convey complex or deeply held eschatological beliefs, but only
the vaguest ideas about heroisation and survival after death. Part
three deals with the decoration of the garland sarcophagi. The
decorative repertoire, though reduced, is not radically different
from that used on the cinerary monuments,the predominance of mythological
(mainly non—bacchic) scenes being its major feature. These,
however, do not seem to express any coherent philosophical or religious
concept of death and the afterlife which might explain the change in
burial rite. The conclusion is that a group of educated, probably
noble, families were responsible for introducing sarcophagi to
Roman society, but that this does not reflect a radical change in
eschatological ideas, only a change in fashion
A new role for pond management in farmland bird conservation
Biodiversity declines in agricultural landscapes represent a major conservation challenge. In the UK, some agricultural landscapes contain high pond densities, but many farmland ponds have become terrestrialised since the 1960s, with input of organic material resulting in a decrease in the size and depth of ponds that eventually transform into wet woodland habitats. Pond management, including removal of overhanging scrub and sediment, has proven highly effective in enhancing freshwater biodiversity. However, the implications of this management for farmland bird assemblages are unknown. Bird surveys were undertaken at recently managed, open, macrophyte-dominated and at highly terrestrialised, macrophyte-free ponds in the intensively cultivated farmland of North Norfolk, UK. The diversity, abundance and composition of bird assemblages visiting these ponds were compared to determine responses to pond management by tree and mud removal. Avian species richness, abundance and bird-visit frequencies were all higher at open farmland ponds. The observed patterns of bird occurrence were best explained by management-induced reductions in tree shading that resulted in aquatic macrophyte-dominance likely associated with high emergent invertebrate prey abundance. Moreover, we predict that open-canopy ponds offer greater habitat heterogeneity than overgrown ponds, allowing diversified bird use. Overgrown, terrestrialised ponds were preferred by some woodland bird species. Gamma diversity across the entire pondscape exceeded all individual pond alpha diversity measures by an order of magnitude, suggesting distinct variation in the bird assemblages visiting farmland ponds during different successional stages. Pond management that generates a mosaic of pond successional stages, including open-canopy, macrophyte-dominated ponds, could help to address the long-term decline of farmland birds. We strongly advocate increased agro-ecological research in this field, combined with greater emphasis on ponds and pond management options in agri-environment schemes
Improving the kinetic couplings in lattice nonrelativistic QCD
We improve the non-relativistic QCD (NRQCD) action by comparing the
dispersion relation to that of the continuum through in
perturbation theory. The one-loop matching coefficients of the
kinetic operators are determined, as well as the scale at
which to evaluate in the -scheme for each quantity. We utilise
automated lattice perturbation theory using twisted boundary conditions as an
infrared regulator. The one-loop radiative corrections to the mass
renormalisation, zero-point energy and overall energy-shift of an NRQCD
-quark are also found. We also explore how a Fat-smeared NRQCD action and
changes of the stability parameter affect the coefficients. Finally, we use
gluon field ensembles at multiple lattice spacing values, all of which include
, , and quark vacuum polarisation, to test how the improvements
affect the non-perturbatively determined and
kinetic masses, and the tuning of the quark mass
Iron oxidation at low temperature (260–500 C) in air and the effect of water vapor
The oxidation of iron has been studied at low temperatures (between 260 and 500 C) in dry air or air with 2 vol% H2O, in the framework of research on dry corrosion of nuclear waste containers during long-term interim storage. Pure iron is regarded as a model material for low-alloyed steel. Oxidation tests were performed in a thermobalance (up to 250 h) or in a laboratory furnace (up to 1000 h). The oxide scales formed were characterized using SEM-EDX, TEM, XRD, SIMS and EBSD techniques. The parabolic rate constants deduced from microbalance experiments were found to be in good agreement with the few existing values of the literature. The presence of water vapor in air was found to strongly influence the transitory stages of the kinetics. The entire structure of the oxide scale was composed of an internal duplex magnetite scale made of columnar grains and an external hematite scale made of equiaxed grains. 18O tracer experiments performed at 400 C allowed to propose a growth mechanism of the scale
Chaos and Elliptical Galaxies
Recent results on chaos in triaxial galaxy models are reviewed. Central mass
concentrations like those observed in early-type galaxies -- either stellar
cusps, or massive black holes -- render most of the box orbits in a triaxial
potential stochastic. Typical Liapunov times are 3-5 crossing times, and
ensembles of stochastic orbits undergo mixing on time scales that are roughly
an order of magnitude longer. The replacement of the regular orbits by
stochastic orbits reduces the freedom to construct self-consistent equilibria,
and strong triaxiality can be ruled out for galaxies with sufficiently high
central mass concentrations.Comment: uuencoded gziped PostScript, 12 pages including figure
The human liver microenvironment shapes the homing and function of CD4+ T-cell populations.
OBJECTIVE: Tissue-resident memory T cells (TRM) are vital immune sentinels that provide protective immunity. While hepatic CD8+ TRM have been well described, little is known about the location, phenotype and function of CD4+ TRM. DESIGN: We used multiparametric flow cytometry, histological assessment and novel human tissue coculture systems to interrogate the ex vivo phenotype, function and generation of the intrahepatic CD4+ T-cell compartment. We also used leukocytes isolated from human leukocyte antigen (HLA)-disparate liver allografts to assess long-term retention. RESULTS: Hepatic CD4+ T cells were delineated into three distinct populations based on CD69 expression: CD69-, CD69INT and CD69HI. CD69HICD4+ cells were identified as tissue-resident CD4+ T cells on the basis of their exclusion from the circulation, phenotypical profile (CXCR6+CD49a+S1PR1-PD-1+) and long-term persistence within the pool of donor-derived leukcoocytes in HLA-disparate liver allografts. CD69HICD4+ T cells produced robust type 1 polyfunctional cytokine responses on stimulation. Conversely, CD69INTCD4+ T cells represented a more heterogenous population containing cells with a more activated phenotype, a distinct chemokine receptor profile (CX3CR1+CXCR3+CXCR1+) and a bias towards interleukin-4 production. While CD69INTCD4+ T cells could be found in the circulation and lymph nodes, these cells also formed part of the long-term resident pool, persisting in HLA-mismatched allografts. Notably, frequencies of CD69INTCD4+ T cells correlated with necroinflammatory scores in chronic hepatitis B infection. Finally, we demonstrated that interaction with hepatic epithelia was sufficient to generate CD69INTCD4+ T cells, while additional signals from the liver microenvironment were required to generate liver-resident CD69HICD4+ T cells. CONCLUSIONS: High and intermediate CD69 expressions mark human hepatic CD4+ TRM and a novel functionally distinct recirculating population, respectively, both shaped by the liver microenvironment to achieve diverse immunosurveillance
The human liver microenvironment shapes the homing and function of CD4+ T-cell populations
OBJECTIVE: Tissue-resident memory T cells (TRM) are vital immune sentinels that provide protective immunity. While hepatic CD8+ TRM have been well described, little is known about the location, phenotype and function of CD4+ TRM. DESIGN: We used multiparametric flow cytometry, histological assessment and novel human tissue coculture systems to interrogate the ex vivo phenotype, function and generation of the intrahepatic CD4+ T-cell compartment. We also used leukocytes isolated from human leukocyte antigen (HLA)-disparate liver allografts to assess long-term retention. RESULTS: Hepatic CD4+ T cells were delineated into three distinct populations based on CD69 expression: CD69−, CD69INT and CD69HI. CD69HICD4+ cells were identified as tissue-resident CD4+ T cells on the basis of their exclusion from the circulation, phenotypical profile (CXCR6+CD49a+S1PR1−PD-1+) and long-term persistence within the pool of donor-derived leukcoocytes in HLA-disparate liver allografts. CD69HICD4+ T cells produced robust type 1 polyfunctional cytokine responses on stimulation. Conversely, CD69INTCD4+ T cells represented a more heterogenous population containing cells with a more activated phenotype, a distinct chemokine receptor profile (CX3CR1+CXCR3+CXCR1+) and a bias towards interleukin-4 production. While CD69INTCD4+ T cells could be found in the circulation and lymph nodes, these cells also formed part of the long-term resident pool, persisting in HLA-mismatched allografts. Notably, frequencies of CD69INTCD4+ T cells correlated with necroinflammatory scores in chronic hepatitis B infection. Finally, we demonstrated that interaction with hepatic epithelia was sufficient to generate CD69INTCD4+ T cells, while additional signals from the liver microenvironment were required to generate liver-resident CD69HICD4+ T cells. CONCLUSIONS: High and intermediate CD69 expressions mark human hepatic CD4+ TRM and a novel functionally distinct recirculating population, respectively, both shaped by the liver microenvironment to achieve diverse immunosurveillance
Habitat Selection of Three Neotropical Grassland Birds Is Dependent on Vegetation Structure and Resources
Grassland birds are globally imperiled. Those of endemic Neotropical savannas may be particularly threatened as knowledge of the ecology of many species is lacking, restricting our ability to take decisive conservation action. During the dry (non-breeding) season of 2010, we studied the population size, distribution, and habitat associations of the Cock-tailed Tyrant (Alectrurus tricolor), Black-masked Finch (Coryphaspiza melanotis), and Wedge-tailed Grass-finch (Emberiziodes herbicola) across a disturbance-mediated savanna–grassland gradient in Beni, Bolivia. We used distance sampling and surveyed structural and resource-specific habitat features at plots where birds were present versus random locations. Occupancy models identified fine-scale habitat associations. Cock-tailed Tyrant (7.1 ind./km2) specialized on open habitats in areas expected to be heavily inundated in the wet season, avoided trees, and selected tall grassy swards. Black-masked Finch (25.1 ind./km2) occurred across the gradient, associating with tall, forb-rich swards, sparse shrubs, and low levels of fruiting and seeding vegetation. Wedge-tailed Grass-finch (27.9 ind./km2) also occurred across the gradient, particularly associated with tall, forb-rich swards, abundant seeding grasses, and sparse shrubs. Our results offer the first quantitative abundance estimates for these species in Beni, provide vital baselines for future monitoring, and improve knowledge of the ecology and conservation management needs of these species. Importantly, our results suggest that populations of these three grassland birds may be best maintained in heterogenous, mosaic landscapes that can be produced by carefully managed burning and grazing. Further research in the breeding season would facilitate making stronger, more specific management recommendations
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