4,608 research outputs found
Immunodepression During Urethane and N-Nitrosomethylurea Leukaemogenesis in Mice
Five injections of urethane, 1 mg./g. body weight to suckling mice markedly reduced the primary immune response against sheep red blood cells assessed by splenic plaque forming cells (PFC) determination and haemagglutinin (HA) titration. The immunological impairment lasted for about 50 days after the end of the treatment. The secondary response tested by HA titration was not affected. A lower dose of urethane (0.5 mg./g.) produced only a delay of the primary HA response. A single neonatal dose of N-nitrosomethylurea (NMU) caused a profound immunodepression evaluated as HA titre and number of PFC. Both primary and secondary responses were still depressed when tested at 50 and 90 days of age respectively. No clear correlation between the degree of immunodepression and lymphoma development was found
Depositional architecture of a mixed travertine-terrigenous system in a fault-controlled continental extensional basin (Messinian, Southern Tuscany, Central Italy)
The extensional Neogene Albegna Basin (Southern Tuscany, Italy) includes several thermogene travertine units dating from the Miocene to Holocene time. During the late Miocene (Messinian), a continental fault-controlled basin (of nearly 500-km2 width) was filled by precipitated travertine and detrital terrigenous strata, characterized by a wedge-shaped geometry that thinned northward, with a maximum thickness of nearly 70m. This mixed travertine-terrigenous succession was investigated in terms of lithofacies types, depositional environment and architecture and the variety of precipitated travertine fabrics. Deposited as beds with thickness ranging from centimetres to a few decimetres, carbonates include nine travertine facies types: F1) clotted peloidal micrite and microsparite boundstone, F2) raft rudstone/floatstone, F3) sub-rounded radial coated grain grainstone, F4) coated gas bubble boundstone, F5) crystalline dendrite cementstone, F6) laminated boundstone, F7) coated reed boundstone and rudstone, F8) peloidal skeletal grainstone and F9) calci-mudstone and microsparstone. Beds of terrigenous deposits with thickness varying from a decimetre to > 10 m include five lithofacies: F10) breccia, F11) conglomerate, F12) massive sandstone, F13) laminated sandstone and F14) claystone. The succession recorded the following three phases of evolution of the depositional setting: 1) At the base, a northward-thinning thermogene travertine terraced slope (Phase I, travertine slope lithofacies association, F1-F6) developed close to the extensional fault system, placed southward with respect to the travertine deposition. 2) In Phase II, the accumulation of travertines was interrupted by the deposition of colluvial fan deposits with a thickness of several metres (colluvial fan lithofacies association, F10 and F12), which consisted of massive breccias, adjacent to the alluvial plain lithofacies association (F11-F14) including massive claystone and sandstone and channelized conglomerates. Travertine lenses, of 2-3-m thickness, appeared intermittently alternating with the colluvial fan breccias. 3) In the third phase, the filled fault-controlled basin evolved into an alluvial plain with ponds rich in coated reed travertines, which record the influence of freshwater (travertine flat lithofacies association, F7-F9). This study shows the stratigraphic architecture and sedimentary evolution of a continental succession, wherein the hydrothermal activity and consequent travertine precipitation were driven by the extensional tectonic regime, with faults acting as fluid paths for the thermal water. Fault activity created the accommodation space for travertine and colluvial fan accumulation. Erosion of the uplifted footwall blocks provided the source of sediments for the colluvial fan breccias, which alternated with the thermogene travertine precipitation. Climatic oscillations might have led to the recharge of the aquifer that fed the hydrothermal vents. The studied continental succession in an extensional basin provides valuable information about the interplay between thermogene travertine and alluvial/colluvial deposition, which in turn might improve the understanding of similar fault-controlled continental depositional systems in outcrops and the subsurface
Embryonic Antigens and Growth of Murine Fibrosarcomata
The amount of embryonic antigens (EA) was estimated in 13 BALB/c fibrosarcomata by in vitro cell mediated cytotoxicity of anti-embryo spleen cells and by quantitative absorption of an anti-embryo antiserum. A direct relationship between amount of EA and tumour growing capacity was found. EA were detected also on fast dividing testicular cells. It is suggested that EA expression on tumour cells is related to a cell membrane function controlling mitosis rather than to a function specifically related to the neoplastic status. Tumour take of low doses of 2 EA-bearing sarcomata was found to be enhanced in anti-embryo immune BALB/c mice in comparison with that in normal and anti-fibroblast immune mice
Recommended from our members
Search for lepton flavour violation in the eĪ¼ continuum with the ATLAS detector in ās = 7 TeV pp collisions at the LHC
This paper presents a search for the t-channel exchange of an R-parity violating scalar top quark (t) in the e^Ā± Ī¼^ā continuum using 2.1 fb^(ā1) of data collected by the ATLAS detector in ās = 7 TeV pp collisions at the Large Hadron Collider. Data are found to be consistent with the expectation from the Standard Model backgrounds. Limits on R-parity-violating couplings at 95 % C.L. are calculated as a function of the scalar top mass (mt). The upper limits on the production cross section for pp ā eĪ¼X, through the t-channel exchange of a scalar top quark, ranges from 170 fb for m_t=95 GeV to 30 fb for m_t=1000 GeV
Using instruments in the study of animate beings:Della Portaās and Baconās experiments with plants
In this paper, I explain Francis Bacon's use of plants as philosophical instruments in the context of his Historia vitae et mortis. My main claim is that Bacon experimented with plants in order to obtain knowledge about the hidden processes of nature, knowledge that could be transferred to the human case and used for the prolongation of life. Bacon's experiments were based on Giambattista della Porta's reports from the Magia naturalis, but I show how a different metaphysics and research method made Bacon systematically rework, reconceptualise, and put to divergent uses the results of the same experimental reports
Recommended from our members
A search for tt resonances with the ATLAS detector in 2.05 fb^(ā1) of proton-proton collisions at ās =7 TeV
A search for top quark pair resonances in final states containing at least one electron or muon has been performed with the ATLAS experiment at the CERN Large Hadron Collider. The search uses a data sample corresponding to an integrated luminosity of 2.05 fb^(ā1), which was recorded in 2011 at a proton-proton centre-of-mass energy of 7 TeV. No evidence for a resonance is found and limits are set on the production cross-section times branching ratio to tt for narrow and wide resonances. For narrow Zā² bosons, the observed 95 % Bayesian credibility level limits range from 9.3 pb to 0.95 pb for masses in the range of m_(Zā²)=500 GeV to m_(Zā²)=1300 GeV. The corresponding excluded mass region for a leptophobic topcolour Zā² boson (Kaluza-Klein gluon excitation in the Randall-Sundrum model) is m_(Zā²)<880 GeV (m_(gKK)< 1130 GeV)
The influence of petrography, mineralogy and chemistry on burnability and reactivity of quicklime produced in Twin Shaft Regenerative (TSR) kilns from Neoarchean limestone (Transvaal Supergroup, South Africa)
This study evaluates the influence of chemical, mineralogical and petrographic features of the Neoarchean limestone from the Ouplaas Mine (Griqualand West, South Africa) on its burnability and quicklime reactivity, considering the main use as raw material for high-grade lime production in twin shaft regenerative (TSR) kilns. This limestone consists of laminated clotted peloidal micrite and fenestrate microbial boundstone with herringbone calcite and organic carbon (kerogen) within stylolites. Diagenetic modifications include hypidiotopic dolomite, micrite to microsparite recrystallization, stylolites, poikilotopic calcite, chert and saddle dolomite replacements. Burning and technical tests widely attest that the Neoarchean limestone is sensitive to high temperature, showing an unusual and drastically pronounced sintering or overburning tendency. The slaking reactivity, according to EN 459-2 is high for lime burnt at 1050 A degrees C, but rapidly decreases for lime burnt at 1150 A degrees C. The predominant micritic microbial textures, coupled with the organic carbon, are key-factors influencing the low burnability and the high sintering tendency. The presence of burial cementation, especially poikilotopic calcite, seems to promote higher burnability, either in terms of starting calcination temperature, or in terms of higher carbonate dissociation rate. In fact, the highest calcination velocity determined by thermal analysis is consistent with the highest slaking reactivity of the lower stratum of the quarry, enriched in poikilotopic calcite. Secondly, locally concentered dolomitic marly limestones, and sporadic back shales negatively affects the quicklime reactivity, as well. This study confirms that a multidisciplinary analytical approach is essential for selecting the best raw mix for achieving the highest lime reactivity in TSR kilns
Recommended from our members
Measurement of dijet production with a veto on additional central jet activity in pp collisions at ās = 7TeV using the ATLAS detector
A measurement of jet activity in the rapidity interval bounded by a dijet system is presented. Events are vetoed if a jet with transverse momentum greater than 20 GeV is found between the two boundary jets. The fraction of dijet events that survive the jet veto is presented for boundary jets that are separated by up to six units of rapidity and with mean transverse momentum 50ā<āp_Tā<ā500 GeV. The mean multiplicity of jets above the veto scale in the rapidity interval bounded by the dijet system is also presented as an alternative method for quantifying perturbative QCD emission. The data are compared to a next-to-leading order plus parton shower prediction from the powheg-box, an all-order resummation using the hej calculation and the pythia, herwig++ and alpgen event generators. The measurement was performed using pp collisions at ās=7 TeV using data recorded by the ATLAS detector in 2010
- ā¦