3,616 research outputs found
Conception and preliminary evaluation of an optical fibre sensor for simultaneous measurement of pressure and temperature
peer-reviewedThis paper presents a novel concept of simultaneously measuring pressure and
temperature using a silica optical fibre extrinsic Fabry-Perot interferometric (EFPI) pressure
sensor incorporating a fibre Bragg grating (FBG), which is constructed entirely from fusedsilica.
The novel device is used to simultaneously provide accurate pressure and temperature
readings at the point of measurement. Furthermore, the FBG temperature measurement is used
to eliminate the temperature cross-sensitivity of the EFPI pressure sensorPUBLISHEDpeer reviewe
The effect of nitrogen fertilization and no-till duration on soil nitrogen availability and greenhouse gas emissions
Non-Peer ReviewedWith a world population now greater than seven billion, it is imperative to conserve the
arable land base, which is increasingly being leveraged by global demands for producing food,
feed, fibre, and fuel. A key component of sustainable agriculture involves the restoration of
unproductive lands that have been rendered unsuitable for agricultural production through
anthropogenic soil degradation. The objective of this study was to determine the effect of
varying fertilizer N rates on soil N availability and N2O and CO2 emissions of three soils
collected at adjacent locations with contrasting management histories: native prairie or short-term
(10 years) and long-term (32 years) no-till continuous multi-crop (wheat-pea-canola)
cropping systems receiving five fertilizer N rates (0, 30, 60, 90, and 120 kg N/ha) for the
previous nine years. Intact soil cores were collected from each site, maintained at field capacity,
and incubated (22 oC) for six weeks. Weekly assessments of soil nutrient availability and N2O
and CO2 emissions were completed to assess the impact of prolonged variable rates of fertilizer
N and duration of no-till management of degraded agricultural soil relative to an adjacent native
prairie soil. At the end of the six-week incubation, there was no significant difference (P > 0.15)
in cumulative soil N supply rate between the unfertilized long-term no-till soil and native soil.
Annual fertilizer N additions of 120 kg N/ha for the previous nine years were required to restore
the N supplying power of the short-term no-till soil to that of the native soil, through the build-up
of mineralizable N levels. As expected, repeated applications of fertilizer N increased the
residual soil N levels in the cultivated soils compared to the native soil. The estimated
cumulative CO2-C and N2O-N emissions at the end of the six-week incubation ranged from
231.8-474.7 g/m2 to 183.9-862.5 mg/m2, respectively. Repeated applications of â„ 60 kg N/ha
supported larger N2O-N fluxes in the long-term no-till soil compared to the unfertilized control.
Highest CO2-C fluxes from the native prairie soil are consistent with its high organic matter
content and contributions from root respiration. Surprisingly, the native prairie soil N2O-N
emissions were equal to those from LTNT and STNT soils receiving repeated fertilizer N
applications at typical agronomic rates and is probably characteristic of rapid denitrification rates
during the dormant vegetative period after snow melt prior to the growing season within
temperate native grassland environments. The use of modern no-till continuous multi-crop
cropping systems, along with application of fertilizer N, enhances the soil N supplying power
over the long-term through the build-up of mineralizable N and appears to be an effective
management strategy for improving degraded soils, thus enhancing the productive capacity of
agricultural ecosystems. However, accounting for N2O emissions associated with repeated
fertilizer N applications is imperative for properly assessing the net global warming potential of
any land management system
Heating of the molecular gas in the massive outflow of the local ultraluminous-infrared and radio-loud galaxy 4C12.50
We present a comparison of the molecular gas properties in the outflow vs. in
the ambient medium of the local prototype radio-loud and ultraluminous-infrared
galaxy 4C12.50 (IRAS13451+1232), using new data from the IRAM Plateau de Bure
interferometer and 30m telescope, and the Herschel space telescope. Previous
H_2 (0-0) S(1) and S(2) observations with the Spitzer space telescope had
indicated that the warm (~400K) molecular gas in 4C12.50 is made up of a
1.4(+-0.2)x10^8 M_sun ambient reservoir and a 5.2(+-1.7)x10^7 M_sun outflow.
The new CO(1-0) data cube indicates that the corresponding cold (25K) H_2 gas
mass is 1.0(+-0.1)x10^10 M_sun for the ambient medium and <1.3x10^8 M_sun for
the outflow, when using a CO-intensity-to-H_2-mass conversion factor alpha of
0.8 M_sun /(K km/s pc^2). The combined mass outflow rate is high, 230-800
M_sun/yr, but the amount of gas that could escape the galaxy is low. A
potential inflow of gas from a 3.3(+-0.3)x10^8 M_sun tidal tail could moderate
any mass loss. The mass ratio of warm-to-cold molecular gas is >= 30 times
higher in the outflow than in the ambient medium, indicating that a
non-negligible fraction of the accelerated gas is heated to temperatures at
which star formation is inefficient. This conclusion is robust against the use
of different alpha factor values, and/or different warm gas tracers (H_2 vs.
H_2 plus CO): with the CO-probed gas mass being at least 40 times lower at 400K
than at 25K, the total warm-to-cold mass ratio is always lower in the ambient
gas than in the entrained gas. Heating of the molecular gas could facilitate
the detection of new outflows in distant galaxies by enhancing their emission
in intermediate rotational number CO lines.Comment: A&A, in pres
A 450-day light curve of the radio afterglow of GRB 970508: Fireball calorimetry
We report on the results of an extensive monitoring campaign of the radio
afterglow of GRB 970508, lasting 450 days after the burst. The spectral and
temporal radio behavior indicate that the fireball has undergone a transition
to sub-relativistic expansion at t~100 days. This allows us to perform
"calorimetry" of the explosion. The derived total energy, ~5\times 10^{50} erg,
is well below the ~5\times 10^{51} erg inferred under the assumption of
spherical symmetry from gamma-ray and early afterglow observations. A natural
consequence of this result, which can also account for deviations at t<100 days
from the spherical relativistic fireball model predictions, is that the
fireball was initially a wide-angle jet of opening angle ~30 degrees.
Our analysis also allows to determine the energy fractions carried by
electrons and magnetic field, and the density of ambient medium surrounding the
fireball. We find that during the sub-relativistic expansion electrons and
magnetic field are close to equipartition, and that the density of the ambient
medium is ~1/cm^3. The inferred density rules out the possibility that the
fireball expands into a strongly non-uniform medium, as would be expected,
e.g., in the case of a massive star progenitor.Comment: 33 pages, including 7 figures, submitted to Ap
Finite Action in d5 Gauged Supergravity and Dilatonic Conformal Anomaly for Dual Quantum Field Theory
Gauged supergravity (SG) with single scalar (dilaton) and arbitrary scalar
potential is considered. Such dilatonic gravity describes special RG flows in
extended SG where scalars lie in one-dimensional submanifold of total space.
The surface counterterm and finite action for such gauged SG in three-, four-
and five-dimensional asymptotically AdS space are derived. Using finite action
and consistent gravitational stress tensor (local surface counterterm
prescription) the regularized expressions for free energy, entropy and mass of
d4 dilatonic AdS black hole are found. The same calculation is done within
standard reference background subtraction.
The dilaton-dependent conformal anomaly from d3 and d5 gauged SGs is
calculated using AdS/CFT correspondence. Such anomaly should correspond to two-
and four-dimensional dual quantum field theory which is classically (not
exactly) conformally invariant, respectively. The candidate c-functions from d3
and d5 SGs are suggested. These c-functions which have fixed points in
asymptoticaly AdS region are expressed in terms of dilatonic potential and they
are positively defined and monotonic for number of potentials.Comment: LaTeX file, 46 pages, two appendixes and some clarifications are
adde
The magnetic field structure in CTA 102 from high-resolution mm-VLBI observations during the flaring state in 2016-2017
CONTEXT: Investigating the magnetic field structure in the innermost regions of relativistic jets is fundamental to understanding the crucial physical processes giving rise to jet formation, as well as to their extraordinary radiation output up to Îł-ray energies.
AIMS: We study the magnetic field structure of the quasar CTA 102 with 3 and 7 mm VLBI polarimetric observations, reaching an unprecedented resolution (âŒ50 ÎŒas). We also investigate the variability and physical processes occurring in the source during the observing period, which coincides with a very active state of the source over the entire electromagnetic spectrum.
METHODS: We perform the Faraday rotation analysis using 3 and 7 mm data and we compare the obtained rotation measure (RM) map with the polarization evolution in 7 mm VLBA images. We study the kinematics and variability at 7 mm and infer the physical parameters associated with variability. From the analysis of Îł-ray and X-ray data, we compute a minimum Doppler factor value required to explain the observed high-energy emission.
RESULTS: Faraday rotation analysis shows a gradient in RM with a maximum value of âŒ6 Ă 104⎠rad mâ»ÂČ and intrinsic electric vector position angles (EVPAs) oriented around the centroid of the core, suggesting the presence of large-scale helical magnetic fields. Such a magnetic field structure is also visible in 7 mm images when a new superluminal component is crossing the core region. The 7 mm EVPA orientation is different when the component is exiting the core or crossing a stationary feature at âŒ0.1 mas. The interaction between the superluminal component and a recollimation shock at âŒ0.1 mas could have triggered the multi-wavelength flares. The variability Doppler factor associated with such an interaction is large enough to explain the high-energy emission and the remarkable optical flare occurred very close in time.Accepted manuscrip
Targeted delivery of a designed sTRAIL mutant results in superior apoptotic activity towards EGFR-positive tumor cells
Previously, we have shown that epidermal growth factor receptor (EGFR)-selective delivery of soluble tumor necrosis factor-related apoptosis-inducing ligand (sTRAIL), by genetic fusion to antibody fragment scFv425, enhances the tumor-selective pro-apoptotic activity of sTRAIL. Insight into the respective contribution of the agonistic receptors TRAIL-R1 and TRAIL-R2 to TRAIL-induced apoptosis may provide a rational approach to further optimize TRAIL-based therapy. Recently, this issue has been investigated using sTRAIL mutants designed to selectively bind to either receptor. However, the relative contribution of the respective TRAIL receptors, in particular TRAIL-R1, in TRAIL signaling is still unresolved. Here, we fused scFv425 to designed sTRAIL mutant sTRAILmR1â5, reported to selectively activate TRAIL-R1, and investigated the therapeutic apoptotic activity of this novel fusion protein. EGFR-specific binding of scFv425:sTRAILmR1â5 potently induced apoptosis, which was superior to the apoptotic activity of scFv425:sTRAIL-wt and a nontargeted MOCK-scFv:sTRAILmR1â5. During cotreatment with cisplatin or the histone deacetylase inhibitor valproic acid, scFv425:sTRAILmR1â5 retained its superior pro-apoptotic activity compared to scFv425:sTRAIL-wt. However, in catching-type Enzyme-Linked ImmunoSorbent Assays with TRAIL-R1:Fc and TRAIL-R2:Fc, scFv425:sTRAILmR1â5 was found to not only bind to TRAIL-R1 but also to TRAIL-R2. Binding to TRAIL-R2 also had functional consequences because the apoptotic activity of scFv425:sTRAILmR1â5 was strongly inhibited by a TRAIL-R2 blocking monoclonal antibody. Moreover, scFv425:sTRAILmR1â5 retained apoptotic activity upon selective knockdown of TRAIL-R1 using small inhibitory RNA. Collectively, these data indicate that both agonistic TRAIL receptors are functionally involved in TRAIL signaling by scFv425:sTRAILmR1â5 in solid tumor cells. Moreover, the superior target cell-restricted apoptotic activity of scFv425:sTRAILmR1â5 indicates its therapeutic potential for EGFR-positive solid tumors
Characterization of a glycosphingolipid antigen defined by the monoclonal antibody MBr1 expressed in normal and neoplastic epithelial cells of human mammary gland
The antigen defined by a monoclonal antibody, MBr1, was found to be expressed in normal human mammary gland epithelia and human mammary carcinoma cells (Menard, S., Tagliabue, E., Canevari, S., Fossati, G., and Colnaghi, M. I. (1983) Cancer Res. 43, 1295-1300). The antigen has been isolated from breast cancer cell line MCF-7, which was used as immunogen, and its structure was determined by methylation analysis, NMR spectroscopy, direct probe mass spectrometry, and enzymatic degradation as identified below. Fuc alpha 1----2Gal beta 1----3GalNAc beta 1----3Gal alpha 1----4Gal beta 1----4Glc beta 1----1Cer The antibody cross-reacted weakly with fucosylasialo-GM1 (IV2FucGg4), which shares the same terminal sequence, Fuc alpha 1----2Gal beta 1----3GalNAc, with this antigen. However, various other structures, including lacto-series H structure (Fuc alpha 1----2 Gal beta 1----4/or 3GlcNAc beta 1----3Gal), did not show any reactivity with this antibody. Therefore, this antigen represents a blood group H antigen with a globo-series structure which is abundant in human teratocarcinoma (Kannagi, R., Levery, S. B., Ishigami, F., Hakomori, S., Shevinsky, L. H., Knowles, B. B., and Solter, D. (1983) J. Biol. Chem. 258, 8934-8942), although its presence must be limited in normal adult human tissue
ISO observations of a sample of Compact Steep Spectrum and GHz Peaked Spectrum Radio Galaxies
We present results from observations obtained with ISOPHOT, on board the ISO
satellite, of a representative sample of seventeen CSS/GPS radio galaxies and
of a control sample of sixteen extended radio galaxies spanning similar ranges
in redshift (0.2 = 10^26 W/Hz).
The observations have been performed at lambda = 60, 90, 174 and 200 microns.
Seven of the CSS/GPS sources have detections >= 3 sigma at one or more
wavelengths, one of which is detected at >= 5 sigma. By co-adding the data we
have obtained average flux densities at the four wavelengths. We found no
evidence that the FIR luminosities of the CSS/GPS sources are significantly
different from those of the extended objects and therefore there is not any
support for CSS/GPS sources being objects "frustrated" by an abnormally dense
ambient medium. The two samples were then combined, providing FIR information
on a new sample of radio galaxies at intermediate redshifts. We compare this
information with what previously known from IRAS and discuss the average
properties of radio galaxies in the redshift range 0.2 - 0.8. The FIR emission
cannot be accounted for by extrapolation of the synchrotron radio spectrum and
we attribute it to thermal dust emission. The average FIR luminosity is >=
6*10^11 L_sun. Over the observed frequency range the infrared spectrum can be
described by a power law with spectral index alpha >~1.0 +/- 0.2. Assuming the
emission to be due to dust, a range of temperatures is required, from >=80 K to
\~25 K. The dust masses required to explain the FIR emission range from 5*10^5
M_sun for the hotter component up to 2*10^8 M_sun for the colder one.
(abridged)Comment: Astronomy & Astrophysics, in press, 16 pages, 2 Figure
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