278 research outputs found
Ethylene signalling affects susceptibility of tomatoes to Salmonella
Fresh fruits and vegetables are increasingly recognized as important reservoirs of human pathogens, and therefore, significant attention has been directed recently to understanding mechanisms of the interactions between plants and enterics, like Salmonella. A screen of tomato cultivars for their susceptibility to Salmonella revealed significant differences in the ability of this human pathogen to multiply within fruits; expression of the Salmonella genes (cysB, agfB, fadH) involved in the interactions with tomatoes depended on the tomato genotype and maturity stage. Proliferation of Salmonella was strongly reduced in the tomato mutants with defects in ethylene synthesis, perception and signal transduction. While mutation in the ripening-related ethylene receptor Nr resulted only in a modest reduction in Salmonella numbers within tomatoes, strong inhibition of the Salmonella proliferation was observed in rin and nor tomato mutants. RIN and NOR are regulators of ethylene synthesis and ripening. A commercial tomato variety heterozygous for rin was less susceptible to Salmonella under the greenhouse conditions but not when tested in the field over three production seasons
Imaging the Earth's Interior: the Angular Distribution of Terrestrial Neutrinos
Decays of radionuclides throughout the Earth's interior produce geothermal
heat, but also are a source of antineutrinos. The (angle-integrated)
geoneutrino flux places an integral constraint on the terrestrial radionuclide
distribution. In this paper, we calculate the angular distribution of
geoneutrinos, which opens a window on the differential radionuclide
distribution. We develop the general formalism for the neutrino angular
distribution, and we present the inverse transformation which recovers the
terrestrial radioisotope distribution given a measurement of the neutrino
angular distribution. Thus, geoneutrinos not only allow a means to image the
Earth's interior, but offering a direct measure of the radioactive Earth, both
(1) revealing the Earth's inner structure as probed by radionuclides, and (2)
allowing for a complete determination of the radioactive heat generation as a
function of radius. We present the geoneutrino angular distribution for the
favored Earth model which has been used to calculate geoneutrino flux. In this
model the neutrino generation is dominated by decays in the Earth's mantle and
crust; this leads to a very ``peripheral'' angular distribution, in which 2/3
of the neutrinos come from angles > 60 degrees away from the downward vertical.
We note the possibility of that the Earth's core contains potassium; different
geophysical predictions lead to strongly varying, and hence distinguishable,
central intensities (< 30 degrees from the downward vertical). Other
uncertainties in the models, and prospects for observation of the geoneutrino
angular distribution, are briefly discussed. We conclude by urging the
development and construction of antineutrino experiments with angular
sensitivity. (Abstract abridged.)Comment: 25 pages, RevTeX, 7 figures. Comments welcom
Reactor Neutrino Experiments with a Large Liquid Scintillator Detector
We discuss several new ideas for reactor neutrino oscillation experiments
with a Large Liquid Scintillator Detector. We consider two different scenarios
for a measurement of the small mixing angle with a mobile
source: a nuclear-powered ship, such as a submarine or an
icebreaker, and a land-based scenario with a mobile reactor. The former setup
can achieve a sensitivity to at the 90%
confidence level, while the latter performs only slightly better than Double
Chooz. Furthermore, we study the precision that can be achieved for the solar
parameters, and , with a mobile reactor
and with a conventional power station. With the mobile reactor, a precision
slightly better than from current global fit data is possible, while with a
power reactor, the accuracy can be reduced to less than 1%. Such a precision is
crucial for testing theoretical models, e.g. quark-lepton complementarity.Comment: 18 pages, 3 figures, 2 tables, revised version, to appear in JHEP,
Fig. 1 extended, Formula added, minor changes, results unchange
Mimicking diffuse supernova antineutrinos with the Sun as a source
Measuring the electron antineutrino component of the cosmic diffuse supernova
neutrino background (DSNB) is the next ambitious goal for low-energy neutrino
astronomy. The largest flux is expected in the lowest accessible energy bin.
However, for E < 15 MeV a possible signal can be mimicked by a solar electron
antineutrino flux that originates from the usual 8B neutrinos by spin-flavor
oscillations. We show that such an interpretation is possible within the
allowed range of neutrino electromagnetic transition moments and solar
turbulent field strengths and distributions. Therefore, an unambiguous
detection of the DSNB requires a significant number of events at E > 15 MeV.Comment: 4 pages, 1 figur
The see-saw mechanism: neutrino mixing, leptogenesis and lepton flavor violation
The see-saw mechanism to generate small neutrino masses is reviewed. After
summarizing our current knowledge about the low energy neutrino mass matrix we
consider reconstructing the see-saw mechanism. Low energy neutrino physics is
not sufficient to reconstruct see-saw, a feature which we refer to as ``see-saw
degeneracy''. Indirect tests of see-saw are leptogenesis and lepton flavor
violation in supersymmetric scenarios, which together with neutrino mass and
mixing define the framework of see-saw phenomenology. Several examples are
given, both phenomenological and GUT-related. Variants of the see-saw mechanism
like the type II or triplet see-saw are also discussed. In particular, we
compare many general aspects regarding the dependence of LFV on low energy
neutrino parameters in the extreme cases of a dominating conventional see-saw
term or a dominating triplet term. For instance, the absence of mu -> e gamma
or tau -> e gamma in the pure triplet case means that CP is conserved in
neutrino oscillations. Scanning models, we also find that among the decays mu
-> e gamma, tau -> e gamma and tau -> mu gamma the latter one has the largest
branching ratio in (i) SO(10) type I see-saw models and in (ii) scenarios in
which the triplet term dominates in the neutrino mass matrix.Comment: 26 pages, 7 figures. Expanded version of talk given at 10th Workshop
In High Energy Physics Phenomenology (WHEPP 10), January 2008, Chennai,
India. Typos corrected, comments and references adde
Elastic deformation of a fluid membrane upon colloid binding
When a colloidal particle adheres to a fluid membrane, it induces elastic
deformations in the membrane which oppose its own binding. The structural and
energetic aspects of this balance are theoretically studied within the
framework of a Helfrich Hamiltonian. Based on the full nonlinear shape
equations for the membrane profile, a line of continuous binding transitions
and a second line of discontinuous envelopment transitions are found, which
meet at an unusual triple point. The regime of low tension is studied
analytically using a small gradient expansion, while in the limit of large
tension scaling arguments are derived which quantify the asymptotic behavior of
phase boundary, degree of wrapping, and energy barrier. The maturation of
animal viruses by budding is discussed as a biological example of such
colloid-membrane interaction events.Comment: 14 pages, 9 figures, REVTeX style, follow-up on cond-mat/021242
Repressing Anarchy in Neutrino Mass Textures
The recent results that is relatively large, of the order of
the previous upper bound, and the indications of a sizable deviation of
from the maximal value are in agreement with the predictions of
Anarchy in the lepton sector. The quark and charged lepton hierarchies can then
be reproduced in a SU(5) GUT context by attributing non-vanishing
charges, different for each family, only to the SU(5) tenplet states. The fact
that the observed mass hierarchies are stronger for up quarks than for down
quarks and charged leptons supports this idea. As discussed in the past, in the
flexible context of , different patterns of charges can
be adopted going from Anarchy to various types of hierarchy. We revisit this
approach by also considering new models and we compare all versions to the
present data. As a result we confirm that, by relaxing the extreme ansatz of
equal charges for all SU(5) pentaplets and singlets, better
agreement with the data than for Anarchy is obtained without increasing the
model complexity. We also present the distributions obtained in the different
models for the Dirac CP-violating phase. Finally we discuss the relative merits
of these simple models.Comment: v1: 12 pages, 3 figures; v2: 13 pages, 3 figures, text improved,
matches version accepted for publication; v3: submitted to add an
acknowledgment to a networ
CT-guided intratumoural administration of cisplatin/epinephrine gel for treatment of malignant liver tumours
To analyze prospectively the interventional and clinical aspects of computed tomography-guided direct intratumoural injection of a novel chemotherapeutic administration and the parenchymal changes of tumour and necrosis in malignant liver tumours. Eight patients with 17 colorectal liver metastases were treated with a mean of 5.1 injections and nine patients with 13 hepatocellular carcinoma nodules with a mean of 3.1 treatments with computed tomography guided local applications of a novel cisplatin/epinephrine gel. This application provides a higher local and lower systemic drug concentration. Volumes of tumour and necrosis prior and after treatment were measured by computer generated volumetric analysis. Contrast enhanced studies verified pretherapeutic viable tumour volumes with a value of 77.4âml in the metastases and 29.2âml in the hepatocellular carcinoma nodules. Intratumoural drug application resulted in a significant increase of necrosis and a decrease in viable tumour volume to be 68.3âml in metastases and 14.5âml in hepatocellular carcinoma. Local therapy control rate for the follow up to 6 months was 38 and 71% for the group of metastases and hepatocellular carcinoma, respectively. Direct intratumoural injection of cisplatin/epinepthrine injectable gel is a feasible and good tolerated method and results in the development of a statistically significant increase in necrosis in malignant liver tumours. For hepatocellular carcinoma a higher local therapy control rate compared to colorectal metastases can be reported
Cenozoic history of Antarctic glaciation and climate from onshore and offshore studies
The past three decades have seen a sustained and coordinated effort to refine the seismic stratigraphic framework of the Antarctic margin that has underpinned the development of numerous geological drilling expeditions from the continental shelf and beyond. Integration of these offshore drilling datasets covering the Cenozoic era with Antarctic inland datasets, provides important constraints that allow us to understand the role of Antarctic tectonics, the Southern Ocean biosphere, and Cenozoic ice sheet dynamics and ice sheetâocean interactions on global climate as a whole. These constraints are critical for improving the accuracy and precision of future projections of Antarctic ice sheet behaviour and changes in Southern Ocean circulation. Many of the recent advances in this field can be attributed to the community-driven approach of the Scientific Committee on Antarctic Research (SCAR) Past Antarctic Ice Sheet Dynamics (PAIS) research programme and its two key subcommittees: Paleoclimate Records from the Antarctic Margin and Southern Ocean (PRAMSO) and Palaeotopographic-Palaeobathymetric Reconstructions. Since 2012, these two PAIS subcommittees provided the forum to initiate, promote, coordinate and study scientific research drilling around the Antarctic margin and the Southern Ocean. Here we review the seismic stratigraphic margin architecture, climatic and glacial history of the Antarctic continent following the break-up of Gondwanaland in the Cretaceous, with a focus on records obtained since the implementation of PRAMSO. We also provide a forward-looking approach for future drilling proposals in frontier locations critically relevant for assessing future Antarctic ice sheet, climatic and oceanic change.We thank many people who collaborated, by sharing data and ideas, on geoscience research projects under the umbrella of the highly successful Paleoclimate Records from the Antarctic Margin and Southern Ocean (PRAMSO) and Palaeotopographic-Palaeobathymetric Reconstructions subcommittees of the Scientific Committee on Antarctic Research (SCAR) Past Antarctic Ice Sheet scientific program. This synthesis, which reflects our views, would not have been possible without the efforts of these many investigators, most of whom continue their collaborative Antarctic studies, now under the successor SCAR INSTANT programme. Chris Sorlien is thanked for drafting Fig. 3.6. We thank John Anderson, Peter Barrett, Giuliano Brancolini and Alan Cooper for their useful comments and for their continuous dedication to the past Antarctic Ice Sheet evolution reconstructions. We thank Nigel Wardell, Frank Nitsche and Paolo Diviacco for maintaining the Seismic Data Library System and the National Antarctic funding agencies of many countries (Australia, China, Germany, Italy, Japan, Korea, New Zealand, Russia, Spain, the UK, the United States) for supporting geophysical and geological surveys essential for Paleotopographic and Paleobathymetric reconstructions. We thank the International Ocean Discovery Program (IODP) for its support of recent expeditions that arose out of PRAMSO discussions. R.M. was funded by the Royal Society Te ApÄrangi NZ Marsden Fund (grant 18-VUW-089). C.E. acknowledges funding by the Spanish Ministry of Economy, Industry and Competitivity (grants CTM2017-89711-C2-1/2-P), cofunded by the European Union through FEDER funds. L.D.S. and F.D. were funded by the Programma Nazionale delle Ricerche in Antartide (PNRA16_00016 project and PNRA 14_00119). R.Larter and C.D.H. were funded by the BAS Polar Science for Planet Earth Programme and NERC UK IODP grant NE/J006548/1. S.K. was supported by the KOPRI Grant (PE21050). L.P. was funded by the European Unionâs Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 792773 WAMSISE. A.S. and S.G. were funded by NSF Office of Polar Programs (Grants OPP-1744970 (A.S.), -1143836 (A.S.), and -1143843 (S.G.). This is University of Texas Institute for Geophysics Contribution #3784. B.D. acknowledges funding from a Rutherford Foundation Postdoctoral Fellowship (RFT-VUW1804-PD). K.G. and G.K. were funded by AWI research programme Polar Regions and Coasts in the changing Earth System (PACES II) and the Sub-EIS-Obs programme by the Bundesanstalt fĂŒr Geowissenschaften und Rohstoffe (BGR). RL, RM, TN acknowledge support from MBIE Antarctic Science Platform contract ANTA1801
A complete 3D numerical study of the effects of pseudoscalar-photon mixing on quasar polarizations
We present the results of three-dimensional simulations of quasar
polarizations in the presence of pseudoscalar-photon mixing in the
intergalactic medium. The intergalactic magnetic field is assumed to be
uncorrelated in wave vector space but correlated in real space. Such a field
may be obtained if its origin is primordial. Furthermore we assume that the
quasars, located at cosmological distances, have negligible initial
polarization. In the presence of pseudoscalar-photon mixing we show, through a
direct comparison with observations, that this may explain the observed large
scale alignments in quasar polarizations within the framework of big bang
cosmology. We find that the simulation results give a reasonably good fit to
the observed data.Comment: 15 pages, 8 figures, significant changes, to appear in EPJ
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