35,674 research outputs found
Neutrino masses in the economical 3-3-1 model
We show that, in frameworks of the economical 3-3-1 model, the suitable
pattern of neutrino masses arises from the three quite different sources - the
lepton-number conserving, the spontaneous lepton-number breaking and the
explicit lepton-number violating, widely ranging over the mass scales including
the GUT one: , , \om\sim
O(1) \mathrm{TeV} and . At
the tree-level, the model contains three Dirac neutrinos: one massless, two
large with degenerate masses in the order of the electron mass. At the one-loop
level, the left-handed and right-handed neutrinos obtain Majorana masses
in orders of and degenerate in
, while the Dirac masses get a large reduction down to
scale through a finite mass renormalization. In this model, the contributions
of new physics are strongly signified, the degenerations in the masses and the
last hierarchy between the Majorana and Dirac masses can be completely removed
by heavy particles. All the neutrinos get mass and can fit the data.Comment: 15 pages, 8 figure
Angular momentum evolution in laser-plasma accelerators
The transverse properties of an electron beam are characterized by two
quantities, the emittance which indicates the electron beam extend in the phase
space and the angular momentum which allows for non-planar electron
trajectories. Whereas the emittance of electron beams produced in laser- plasma
accelerator has been measured in several experiments, their angular momentum
has been scarcely studied. It was demonstrated that electrons in laser-plasma
accelerator carry some angular momentum, but its origin was not established.
Here we identify one source of angular momentum growth and we present
experimental results showing that the angular momentum content evolves during
the acceleration
Probing electron acceleration and X-ray emission in laser-plasma accelerator
While laser-plasma accelerators have demonstrated a strong potential in the
acceleration of electrons up to giga-electronvolt energies, few experimental
tools for studying the acceleration physics have been developed. In this paper,
we demonstrate a method for probing the acceleration process. A second laser
beam, propagating perpendicular to the main beam is focused in the gas jet few
nanosecond before the main beam creates the accelerating plasma wave. This
second beam is intense enough to ionize the gas and form a density depletion
which will locally inhibit the acceleration. The position of the density
depletion is scanned along the interaction length to probe the electron
injection and acceleration, and the betatron X-ray emission. To illustrate the
potential of the method, the variation of the injection position with the
plasma density is studied
On the direct search for spin-dependent WIMP interactions
We examine the current directions in the search for spin-dependent dark
matter. We discover that, with few exceptions, the search activity is
concentrated towards constraints on the WIMP-neutron spin coupling, with
significantly less impact in the WIMP-proton sector. We review the situation of
those experiments with WIMP-proton spin sensitivity, toward identifying those
capable of reestablishing the balance.Comment: 7 pages, 4 figure
Ultrafast filling of an electronic pseudogap in an incommensurate crystal
We investigate the quasiperiodic crystal (LaS)1.196(VS2) by angle and time
resolved photoemission spectroscopy. The dispersion of electronic states is in
qualitative agreement with band structure calculated for the VS2 slab without
the incommensurate distortion. Nonetheless, the spectra display a temperature
dependent pseudogap instead of quasiparticles crossing. The sudden
photoexcitation at 50 K induces a partial filling of the electronic pseudogap
within less than 80 fs. The electronic energy flows into the lattice modes on a
comparable timescale. We attribute this surprisingly short timescale to a very
strong electron-phonon coupling to the incommensurate distortion. This result
sheds light on the electronic localization arising in aperiodic structures and
quasicrystals
Identification of a small molecule inhibitor of Ebolavirus genome replication and transcription using in silico screening.
Ebola virus (EBOV) causes a severe haemorrhagic fever in humans and has a mortality rate over 50%. With no licensed drug treatments available, EBOV poses a significant threat. Investigations into possible therapeutics have been severely hampered by the classification of EBOV as a BSL4 pathogen. Here, we describe a drug discovery pathway combining in silico screening of compounds predicted to bind to a hydrophobic pocket on the nucleoprotein (NP); with a robust and rapid EBOV minigenome assay for inhibitor validation at BSL2. One compound (MCCB4) was efficacious (EC50 4.8 μM), exhibited low cytotoxicity (CC50 > 100 μM) and was specific, with no effect on either a T7 RNA polymerase driven firefly luciferase or a Bunyamwera virus minigenome. Further investigations revealed that this small molecule inhibitor was able to outcompete established replication complexes, an essential aspect for a potential EBOV treatment
A Difference Version of Nori's Theorem
We consider (Frobenius) difference equations over (F_q(s,t), phi) where phi
fixes t and acts on F_q(s) as the Frobenius endomorphism. We prove that every
semisimple, simply-connected linear algebraic group G defined over F_q can be
realized as a difference Galois group over F_{q^i}(s,t) for some i in N. The
proof uses upper and lower bounds on the Galois group scheme of a Frobenius
difference equation that are developed in this paper. The result can be seen as
a difference analogue of Nori's Theorem which states that G(F_q) occurs as
(finite) Galois group over F_q(s).Comment: 29 page
What to expect from a non-suspicious prostate MRI? A review = Que peut-on attendre d’une IRM prostatique non suspecte ? Une revue de la littérature
BACKGROUND: Many guidelines now recommend multiparametric MRI (mpMRI) prior to an initial or repeat prostate biopsy. However, clinical decision making for men with a non-suspicious mpMRI (Likert or PIRADS score 1-2) varies. OBJECTIVES: To review the most recent literature to answer three questions. (1) Should we consider systematic biopsy if mpMRI is not suspicious? (2) Are there additional predictive factors that can help decide which patient should have a biopsy? (3) Can the low visibility of some cancers be explained and what are the implications? SOURCES: A narrative review was performed in Medline databases using two searches with the terms "MRI" and "prostate cancer" and ("diagnosis" or "biopsy") and ("non-suspicious" or "negative" or "invisible"); "prostate cancer MRI visible". References of the selected articles were screened for additional articles. STUDY SELECTION: Studies published in the last 5 years in English language were assessed for eligibility and selected if data was available to answer one of the three study questions. RESULTS: Considering clinically significant cancer as ISUP grade≥2, the negative predictive value (NPV) of mpMRI in various settings and populations ranges from 76% to 99%, depending on cancer prevalence and the type of confirmatory reference test used. NPV is higher among patients with prior negative biopsy (88-96%), and lower for active surveillance patients (85-90%). The PSA density (PSAd) with a threshold of PSAd<0.15ng/ml/ml was the most studied and relevant predictive factor used in combination with mpMRI to rule out clinically significant cancer. Finally, mpMRI-invisible tumours appear to differ from a histopathological and genetic point of view, conferring clinical advantage to invisibility. LIMITATIONS: Most published data come from expert centres and results may not be reproducible in all settings. CONCLUSION: mpMRI has high diagnostic accuracy and in cases of negative mpMRI, PSA density can be used to determine which patient should have a biopsy. Growing knowledge of the mechanisms and genetics underlying MRI visibility will help develop more accurate risk calculators and biomarkers
DataProVe: Fully Automated Conformance Verification Between Data Protection Policies and System Architectures
Privacy and data protection by design are relevant parts of the General Data Protection Regulation (GDPR), in which businesses and organisations are encouraged to implement measures at an early stage of the system design phase to fulfil data protection requirements. This paper addresses the policy and system architecture design and propose two variants of privacy policy language and architecture description language, respectively, for specifying and verifying data protection and privacy requirements. In addition, we develop a fully automated algorithm based on logic, for verifying three types of conformance relations (privacy, data protection, and functional conformance) between a policy and an architecture specified in our languages’ variants. Compared to related works, this approach supports a more systematic and fine-grained analysis of the privacy, data protection, and functional properties of a system. Our theoretical methods are then implemented as a software tool called DataProVe and its feasibility is demonstrated based on the centralised and decentralised approaches of COVID-19 contact tracing applications
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