1,018 research outputs found
Renormalisation Group Corrections to Neutrino Mass Sum Rules
Neutrino mass sum rules are an important class of predictions in flavour
models relating the Majorana phases to the neutrino masses. This leads, for
instance, to enormous restrictions on the effective mass as probed in
experiments on neutrinoless double beta decay. While up to now these sum rules
have in practically all cases been taken to hold exactly, we will go here
beyond that. After a discussion of the types of corrections that could possibly
appear and elucidating on the theory behind neutrino mass sum rules, we
estimate and explicitly compute the impact of radiative corrections, as these
appear in general and thus hold for whole groups of models. We discuss all
neutrino mass sum rules currently present in the literature, which together
have realisations in more than 50 explicit neutrino flavour models. We find
that, while the effect of the renormalisation group running can be visible, the
qualitative features do not change. This finding strongly backs up the solidity
of the predictions derived in the literature, and it thus marks a very
important step in deriving testable and reliable predictions from neutrino
flavour models.Comment: 25 pages, 3 figures, 39 additional plots; version published in JHE
Information Technology (IT) Change Management
This paper draws upon the work of American Management Systems (AMS) and other practitioners in describing how a realistic and effective IT change model can be constructed. This model will be the basis for our future research into how organizations actually implement change
Barriers To B2C Segment Of E-Business
The purpose of this paper is to identify several barriers affecting B2C segment growth and to project technological advances that may soften or eliminate these barriers. Included in the paper is an analysis of the interrelationship between barriers and products. Finally, the paper presents the impact of technology-controlled and human-controlled factors on Internet sale.  
Influence of Granulocytes on Brain Edema, Intracranial Pressure, and Cerebrospinal Fluid Concentrations of Lactate and Protein in Experimental Meningitis
Brain water content (brain edema), intracranial pressure, and cerebrospinal fluid (CSF) concentrations of lactate and protein increased significantly during 24 h of experimental meningitis due to Streptococcus pneumoniae, but changes were similar in normal and neutropenic rabbits. In sterile meningitis induced by N-formyl-methionyl-leucyl-phenyl-alanine (fMLP), low and high doses of fMLP were equally effective in inducing CSF pleocytosis, whereas only high doses of fMLP caused brain edema. High doses of fMLP injected intracisternally during pneumococcal meningitis also increased brain water content. The fMLP did not significantly increase intracranial pressure or CSF concentrations of lactate or protein in sterile or pneumococcal meningitis, nor did it cause brain edema in neutropenic animals. Thus, granulocytes may contribute to brain edema during meningitis if adequately stimulated, but intracranial pressure and CSF protein and lactate concentrations appear independent of granulocytes. Stimulation does not appear to occur early in meningitis, when granulocytes were without effect on brain edem
Radiative Inflation and Dark Energy
We propose a model based on radiative symmetry breaking that combines
inflation with Dark Energy and is consistent with the WMAP 7-year regions. The
radiative inflationary potential leads to the prediction of a spectral index
0.955 \lesssim n_S \lesssim 0.967 and a tensor to scalar ratio 0.142 \lesssim r
\lesssim 0.186, both consistent with current data but testable by the Planck
experiment. The radiative symmetry breaking close to the Planck scale gives
rise to a pseudo Nambu-Goldstone boson with a gravitationally suppressed mass
which can naturally play the role of a quintessence field responsible for Dark
Energy. Finally, we present a possible extra dimensional scenario in which our
model could be realised.Comment: 15 pages, 4 figures; v2: references added, appendix added, Section 5
slightly modified; content matches published versio
The Postantibiotic Effect in the Treatment of Experimental Meningitis Caused by Streptococcus pneumoniae in Rabbits
The relevance of a postantibiotic effect in the treatment of pneumococcal meningitis was evaluated in a rabbit model. After administration of a single intravenous bolus of ampicillin at various dosages, such an effect was observed in all animals. The duration of this effect in vivo (2.5-18 hr) was consistently longer than that in vitro (1-4.3 hr); however, in rabbits the postantibiotic effect was eliminated by the administration of intravenous plus intracisternal β-lactamase. In an assessment of the potential therapeutic benefit of the postantibiotic effect, the efficacy of two regimens of treatment with different intervals between doses was compared. One group of animals received ampicillin every 4 hr and another every 12 hr. With sufficiently high doses, drug concentrations in cerebrospinal fluid exceeded the minimal bactericidal concentration for most of the 4-hr interval but for only about one-third of the 12-hr interval. The rate of cure was similar for the two regimens and approximated 100% when peak drug concentrations in cerebrospinal fluid exceeded the minimal bactericidal concentration by at least 10-fol
Manganese-Induced Toxicity in C. elegans : What Can We Learn from the Transcriptome?
Manganese (Mn) is an essential ubiquitous transition metal and, when occupationally
or environmentally overexposed, a well-known risk factor for several neurological pathologies.
However, the molecular mechanisms underlying Mn-induced neurotoxicity are largely unknown.
In this study, addressing RNA-Seq analysis, bioavailability and survival assays, key pathways of
transcriptional responses to Mn overexposure were investigated in the model organism Caenorhabditis
elegans (C. elegans), providing insights into the Mn-induced cellular stress and damage response.
Comparative transcriptome analyses identified a large number of differentially expressed genes
(DEGs) in nematodes exposed to MnCl2
, and functional annotation suggested oxidative nucleotide
damage, unfolded protein response and innate immunity as major damage response pathways.
Additionally, a time-dependent increase in the transcriptional response after MnCl2 exposure was
identified by means of increased numbers of DEGs, indicating a time-dependent response and
activation of the stress responses in Mn neurotoxicity. The data provided here represent a powerful
transcriptomic resource in the field of Mn toxicity, and therefore, this study provides a useful basis
for further planning of targeted mechanistic studies of Mn-induced neurotoxicity that are urgently
needed in the face of increasing industrially caused environmental pollution with Mn
Antibiotic Therapy, Endotoxin Concentration in Cerebrospinal Fluid, and Brain Edema in Experimental Escherichia coli Meningitis in Rabbits
We investigated the effect of cefotaxime and chloramphenicol on endotoxin concentrations in cerebrospinal fluid (CSF) and on the development of brain edema in rabbits with Escherichia coli meningitis. Both antibiotics were similarly effective in reducing bacterial titers. Cefotaxime, but not chloramphenicol, induced a marked increase of endotoxin in CSF, from log10 1.5 ± 0.8 to log10 2.8 ± 0.7 ng/ml (P < .01). This result was associated with an increase in brain water content (405 ± 12 g of water/100 g of dry weight compared with 389 ± 8 g in untreated controls; P < .01), whereas in animals treated with chloramphenicol, brain water content was identical to controls. The cefotaxime-induced increase in endotoxin concentration and brain edema were both neutralized by polymyxin B, which binds to the lipid A moiety of endotoxin, or by a monoclonal antibody to lipid A. These results indicate that treating gram-negative bacillary meningitis with selected antibiotics induces increased endotoxin concentrations in CSF that are associated with brain edem
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