169,744 research outputs found
Quasi-degenerate neutrino mass spectrum, μ→e+γ decay and leptogenesis
No full textAbstractIn a large class of SUSY GUT models with see-saw mechanism of neutrino mass generation, lepton flavor violating (LFV) decays μ→e+γ, τ→μ+γ, etc., are predicted with rates that are within the reach of present and planned experiments. A crucial element in these predictions is the matrix of neutrino Yukawa couplings Yν which can be expressed in terms of the light and RH heavy neutrino masses, the neutrino mixing PMNS matrix U, and an orthogonal matrix R. Leptogenesis can take place only if R is complex. Considering the case of quasi-degenerate neutrinos and assuming that R is complex, we derive simple analytical expressions for the μ→e+γ, τ→μ+γ and τ→e+γ decay rates. Taking into account the leptogenesis constraints on the relevant parameters we show that the predicted rates of the LFV decays μ→e+γ, and τ→e+γ are generically enhanced by a factor of ∼103 to ∼106 with respect to the rates calculated for real R, while the τ→μ+γ decay rate is enhanced approximately by two orders of magnitude
Charged Lepton Flavour Violating Decays: Leading Logarithmic Approximation versus Full RGE Results
No full textWe consider the MSSM with see-saw mechanism of neutrino mass generation and soft SUSY breaking with flavour-universal
boundary conditions at the GUT scale,
in which the lepton flavour violating (LFV) decays , , \etc.,
are predicted with rates that can be within the reach of present and
planned experiments. These predictions depend critically on the
matrix of neutrino Yukawa couplings which can be
expressed in terms of the light and heavy right-handed (RH) neutrino
masses, neutrino mixing matrix \pmns, and an orthogonal matrix
. We investigate the effects of Majorana CP-violation
phases in \pmns, and of the RG running of light neutrino masses
and mixing angles from to the RH Majorana neutrino mass scale
, on the predictions for the rates of LFV decays , and . The case of quasi-degenerate heavy RH Majorana
neutrinos is considered. Results for neutrino mass spectrum with
normal hierarchy, values of the lightest -mass in the range eV, and
in the cases of and complex
matrix are presented.
We find that the effects of the
Majorana CP-violation phases and of the RG evolution of neutrino
mixing parameters can change by few orders of magnitude the
predicted rates of the LFV decays and . The impact of these effects on the decay rate is typically smaller and only possible for m_1
\gtap 0.10 eV. If the RG running effects are negligible,
in a large region of soft SUSY breaking
parameter space the ratio of the branching ratios of the and () decays
is entirely determined in the case of
by the values of the neutrino mixing parameters at
Lepton Flavor Violation, Neutralino Dark Matter and the Reach of the LHC
No full textWe revisit the phenomenology of the Constrained MSSM with right-handed neutrinos
(CMSSMRN). A supersymmetric seesaw mechanism, generating neutrino
masses and sizable lepton flavour violating (LFV) entries is assumed to be operative.
In this scheme, we study the complementarity between the ‘observable ranges’
of various paths leading to the possible discovery of low energy SUSY: the reach of
the Cern Large Hadron Collider (LHC), the quest for neutralino dark matter signals
and indirect searches through LFV processes. Within the regions of the CMSSMRN
parameter space compatible with all cosmo-phenomenological requirements, those
which are expected to be probed at the LHC will be typically also accessible to
upcoming LFV experiments. Moreover, parameter space portions featuring a heavy
SUSY particle spectrum could be well beyond LHC reach while leaving LFV searches
as the only key to get a glimpse on SUSY
On the role of neutrinos telescopes in the search for Dark Matter annihilations in the Sun
No full textThe observation of GeV neutrinos coming from the Sun would be a clear signal of dark matter if neutrinos produced by cosmic rays interaction are an irreducible but suppressed background. Current neutrino detectors have so far failed to detect such a signal, however, and bounds from direct and indirect dark matter searches may significantly restrict the possibility of observing it in future experiments such as Hyper-Kamiokande or IceCube-Gen2. In this work we assess, in the light of current data and of expected experimental sensitivities, the prospects for the detection of a neutrino signal from dark matter annihilations in the Sun. To be as general as possible, equilibrium between the capture and the annihilation rates in the Sun is not assumed in our analysis; instead, the dark matter scattering and annihilation cross sections are taken as free and independent parameters. We consider capture via both spin-dependent and spin-independent interactions, and annihilations into three representative final states: b (b) over bar , W (+) W-, and tau (+) tau(-). We find that when the capture in the Sun is dominated by spin-independent interactions, current direct detection bounds already preclude the observation of a neutrino signal in future experiments. For capture via spin-dependent interactions, a strong complementarity is observed, over most of the parameter space, between future neutrino detectors and planned direct and indirect dark matter detection experiments, such as PICO-500 and CTA. In this case, we also identify some regions of the parameter space that can be probed, via the neutrino flux from the Sun, only by future neutrino experiments
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Mitomycin C in highly myopic eyes - Author reply
No full textOphthalmology. 2005 Feb;112(2):208-18; discussion 219.
Mitomycin C modulation of corneal wound healing after photorefractive keratectomy in highly myopic eyes.
Gambato C, Ghirlando A, Moretto E, Busato F, Midena E.
SourceRefractive Surgery Service and Antimetabolite Therapy Research Unit, Department of Ophthalmology, University of Padova, Padova, Italy.
Abstract
PURPOSE: To evaluate the role of topical mitomycin C in corneal wound healing (CWH) after photorefractive keratectomy (PRK) in highly myopic eyes.
DESIGN: Prospective, double-masked, randomized clinical trial.
PARTICIPANTS: Seventy-two eyes of 36 patients affected by high (>7 diopters) myopia.
METHODS: In each patient, one eye was randomly assigned to PRK with intraoperative topical 0.02% mitomycin C application, and the fellow eye was treated with a placebo. Postoperatively, mitomycin C-treated eyes received artificial tears (3 times daily, tapered in 3 months), whereas the fellow eye was treated with fluorometholone sodium 2% and artificial tears (3 times daily, tapered in 3 months).
MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA), contrast sensitivity, manifest refraction, and biomicroscopy. Contrast sensitivity was determined using the Pelli-Robson chart. Corneal confocal microscopy documented CWH.
RESULTS: Mean follow-up was 18 months (range, 12-36). No side effects or toxic effects were documented. At 12-month follow-up examination, UCVAs (logarithm of the minimum angle of resolution) were 0.4+/-0.48 and 0.5+/-0.53 (P = .03) in mitomycin C-treated eyes and corticosteroid-treated eyes, respectively. At 1 year, corneal haze developed in 20% of corticosteroid-treated eyes, versus 0% of mitomycin C-treated eyes. At 12, 24, and 36 months, corneal confocal microscopy showed activated keratocytes and extracellular matrix significantly more evident in untreated eyes (Ps = 0.004, 0.024, and 0.046, respectively).
CONCLUSION: Topical intraoperative application of 0.02% mitomycin C can reduce haze formation in highly myopic eyes undergoing PRK.
Comment in
Ophthalmology. 2006 Feb;113(2):357; author reply 357-8
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
A Multi-Language Comparison of Influences on Author Verification using Character N-Grams
No full textWe create a new multi-language corpus for author verification based on Wikipedia talkpages, and evaluate the influence that differences in topic and time have on character n-gram author profiles. Topic alignment between two texts is found to increase author verification precision, and an authors writing style is found to change over time, but not more significantly after 3 years than after 1 year.Information ArchitectureWISElectrical Engineering, Mathematics and Computer Scienc
A 0.12mm<sup>2</sup> Wien-Bridge Temperature Sensor with 0.1°C (3σ) Inaccuracy from -40°C to 180°C
No full text Resistor-based temperature sensors can achieve much higher resolution and energy efficiency than conventional BJT-based sensors [1], but they typically occupy more area (> 0.25 mm 2 ) and have lower operating temperatures (le 125 {circ} {C}) [2]-[4]. This work describes a 0.12mm 2 resistor-based sensor that uses a Wien-bridge (WB) filter to achieve 0.1 {circ} {C} (3 sigma) inaccuracy from - 40 {circ} {C} to 180 {circ} {C}. Compared to a state-of-the-art WB sensor [4], it occupies 6 × less area and achieves comparable relative accuracy over a 76% wider operating range. Session 10.3 Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic InstrumentationMicroelectronic
A ±25A Versatile Shunt-Based Current Sensor with 10kHz Bandwidth and ±0.25% Gain Error from -40°C to 85°C Using 2-Current Calibration
No full textAccurate current sensing is critical in many industrial applications, such as battery management and motor control. Precise shunt-based current sensors have been reported with gain errors of less than 1% over the industrial temperature range (-40°C to 85°C) [1]–[4]. However, since they are intended for coulomb counting, their bandwidth is limited to a few tens of Hz, making them unsuitable for battery impedance or motor-current sensing. This paper presents a current sensor with a wide (10kHz) bandwidth and a tunable temperature compensation scheme (TCS), which allows it to be flexibly used with different types of shunts while maintaining high accuracy. A low-cost room-temperature calibration scheme is proposed to optimize gain flatness over temperature by exploiting the shunt's self-heating at large currents. Over the industrial temperature range and a ±25A current range, it achieves state-of-the-art gain error (±0.25%) with both low-cost PCB and stable metal-alloy shunts.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic InstrumentationMicroelectronic
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