395 research outputs found
Selective oxidation of aromatic alcohols in the presence of C3N4 photocatalysts derived from the polycondensation of melamine, cyanuric and barbituric acids
A set of C3N4 samples has been prepared by using melamine, cyanuric acid and barbituric acid as the precursors. The materials were subjected both to physical and chemical characterization and were used as photocatalysts for the selective oxidation of aromatic alcohols in water suspension under UV and visible irradiation. The photoactivity of the materials versus the partial oxidation of four substituted benzyl alcohols was investigated. The type and position of the substituents in the aromatic molecule influenced conversion and selectivity to the corresponding aldehyde. The presence of barbituric and cyanuric acids in the preparation method has changed the graphitic-C3N4 structure, and therefore both the characteristics of the material and the ability of light to activate the surface of the photocatalyst. The most active material prepared in the presence of melamine and cyanuric acid showed a remarkable selectivity towards the aldehyde even under visible irradiation
Effects of high-pressure on the structural, vibrational, and electronic properties of monazite-type PbCrO4
We have performed an experimental study of the crystal structure,
lattice-dynamics, and optical properties of PbCrO4 (the mineral crocoite) at
ambient and high pressures. In particular, the crystal structure, Raman-active
phonons, and electronic band-gap have been accurately determined.
X-ray-diffraction, Raman, and optical-absorption experiments have allowed us
also to completely characterize two pressure-induced structural phase
transitions. The first transition is isostructural, maintaining the monoclinic
symmetry of the crystal, and having important consequences in the physical
properties; among other a band-gap collapse is induced. The second one involves
an increase of the symmetry of the crystal, a volume collapse, and probably the
metallization of PbCrO4. The results are discussed in comparison with related
compounds and the effects of pressure in the electronic structure explained.
Finally, the room-temperature equation of state of the low-pressure phases is
also obtained.Comment: 32 pages, 9 figures, 3 table
R--Parity Violating Signals for Chargino Production at LEP II
We study chargino pair production at LEP II in supersymmetric models with
spontaneously broken R-parity. We perform signal and background analyses,
showing that a large region of the parameter space of these models can be
probed through chargino searches at LEP II. In particular, we determine the
attainable limits on the chargino mass as a function of the magnitude of the
effective bilinear R-parity violation parameter , demonstrating that
LEP II is able to unravel the existence of charginos with masses almost up to
its kinematical limit even in the case of R-parity violation. This requires the
study of several final state topologies since the usual MSSM chargino signature
is recovered as . Moreover, for sufficiently large
values, for which the chargino decay mode dominates,
we find through a dedicated Monte Carlo analysis that the mass
bounds are again very close to the kinematic limit. Our results establish the
robustness of the chargino mass limit, in the sense that it is basically
model-independent. They also show that LEP II can establish the existence of
spontaneous R-parity violation in a large region of parameter space should
charginos be produced.Comment: improved analyses; 31 pages and 9 figures (included
Human CLA+ memory T cell and cytokines in psoriasis
Psoriasis is a common inflammatory skin condition resulting from the interplay between epidermal keratinocytes and immunological cellular components. This sustained inflammation is essentially driven by pro-inflammatory cytokines with the IL-23/IL-17 axis playing a critical central role, as proved by the clinical efficacy of their blockade in patients. Among all the CD45R0+ memory T cell subsets, those with special tropism for cutaneous tissues are identified by the expression of the Cutaneous Lymphocyte-associated Antigen (CLA) carbohydrate on their surface, that is induced during T cell maturation particularly in the skin-draining lymph nodes. Because of their ability to recirculate between the skin and blood, circulating CLA+ memory T cells reflect the immune abnormalities found in different human cutaneous conditions, such as psoriasis. Based on this premise, studying the effect of different environmental microbial triggers and psoriatic lesional cytokines on CLA+ memory T cells, in the presence of autologous epidermal cells from patients, revealed important IL-17 cytokines responses that are likely to enhance the pro-inflammatory loop underlying the development of psoriatic lesions. The goal of this mini-review is to present latest data regarding cytokines implicated in plaque and guttate psoriasis immunopathogenesis from the prism of CLA+ memory T cells, that are specifically related to the cutaneous immune system
Novel scalar boson decays in SUSY with broken r-parity
R parity violation can induce mixing of the supersymmetric Higgs bosons with the sneutrinos at the tree level. We study the effect of this mixing on the decays of Higgs scalars as well as sneutrinos in an effective model where the violation of R parity is included in the minimal supersymmetric model through bilinear lepton number violating superpotential terms. We show that a small violation of R parity can lead to a sizeable branching ratio for the supersymmetric Higgs boson decay mode H→χℓ (where χ denotes an electroweak gaugino and ℓ is either a tau neutrino or a tau lepton). Relevant constraints on R parity violation as well as those coming from SUSY particle searches still allow the decay H→χℓ to compete with the conventional decay H\ra b \bar{b}, at least for some ranges of parameters of the model. Moreover, the tau sneutrino will have dominant R parity violating decays to standard model fermions bb¯, τ+τ− or to the invisible mode νν¯ whenever the phase space for R parity conserving channels is closed
Classifying Parkinson’s Disease Patients With Syntactic and Socio-emotional Verbal Measures
Frontostriatal disorders, such as Parkinson’s disease (PD), are characterized by progressive disruption of cortico-subcortical dopaminergic loops involved in diverse higher-order domains, including language. Indeed, syntactic and emotional language tasks have emerged as potential biomarkers of frontostriatal disturbances. However, relevant studies and models have typically considered these linguistic dimensions in isolation, overlooking the potential advantages of targeting multidimensional markers. Here, we examined whether patient classification can be improved through the joint assessment of both dimensions using sentential stimuli. We evaluated 31 early PD patients and 24 healthy controls via two syntactic measures (functional-role assignment, parsing of long-distance dependencies) and a verbal task tapping social emotions (envy, Schadenfreude) and compared their classification accuracy when analyzed in isolation and in combination. Complementarily, we replicated our approach to discriminate between patients on and off medication. Results showed that specific measures of each dimension were selectively impaired in PD. In particular, joint analysis of outcomes in functional-role assignment and Schadenfreude improved the classification accuracy of patients and controls, irrespective of their overall cognitive and affective state. These results suggest that multidimensional linguistic assessments may better capture the complexity and multi-functional impact of frontostriatal disruptions, highlighting their potential contributions in the ongoing quest for sensitive markers of PD.Fil: Baez, Sandra. Universidad de los Andes; ColombiaFil: Herrera, Eduar. Universidad Icesi; ColombiaFil: Trujillo, Catalina. Universidad del Valle; ColombiaFil: Cardona, Juan F.. Universidad del Valle; ColombiaFil: Diazgranados, Jesús A.. Centro Médico de Atención Neurológica Neurólogos de Occidente; ColombiaFil: Pino, Mariana. Universidad Autónoma del Caribe; ColombiaFil: Santamaria Garcia, Hernando. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Hospital Universitario San Ignacio; Colombia. Pontificia Universidad Javeriana; ColombiaFil: Ibañez, Agustin Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Autónoma del Caribe; Colombia. Universidad de San Andrés; Argentina. Universidad Adolfo Ibañez; Chile. University of California; Estados UnidosFil: García, Adolfo Martín. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de San Andrés; Argentina. University of California; Estados Unidos. Universidad Catolica de Cuyo. Facultad de Educacion.; Argentin
Probing neutrino properties with charged scalar lepton decays
Supersymmetry with bilinear R-parity violation provides a predictive
framework for neutrino masses and mixings in agreement with current neutrino
oscillation data. The model leads to striking signals at future colliders
through the R-parity violating decays of the lightest supersymmetric particle.
Here we study charged scalar lepton decays and demonstrate that if the scalar
tau is the LSP (i) it will decay within the detector, despite the smallness of
the neutrino masses, (ii) the relative ratio of branching ratios Br({tilde
tau}_1 --> e sum nu_i)/ Br({tilde tau}_1 --> mu sum nu_i) is predicted from the
measured solar neutrino angle, and (iii) scalar muon and scalar electron decays
will allow to test the consistency of the model. Thus, bilinear R-parity
breaking SUSY will be testable at future colliders also in the case where the
LSP is not the neutralino.Comment: 24 pages, 8 ps figs Report-no.: IFIC/02-33 and ZU-TH 11/0
Sfrp3 modulates stromal-epithelial crosstalk during mammary gland development by regulating Wnt levels
Mammary stroma is essential for epithelial morphogenesis and development. Indeed, postnatal mammary gland (MG) development is controlled locally by the repetitive and bi-directional cross-talk between the epithelial and the stromal compartment. However, the signalling pathways involved in stromal–epithelial communication are not entirely understood. Here, we identify Sfrp3 as a mediator of the stromal–epithelial communication that is required for normal mouse MG development. Using Drosophila wing imaginal disc, we demonstrate that Sfrp3 functions as an extracellular transporter of Wnts that facilitates their diffusion, and thus, their levels in the boundaries of different compartments. Indeed, loss of Sfrp3 in mice leads to an increase of ductal invasion and branching mirroring an early pregnancy state. Finally, we observe that loss of Sfrp3 predisposes for invasive breast cancer. Altogether, our study shows that Sfrp3 controls MG morphogenesis by modulating the stromal-epithelial cross-talk during pubertal development
Spontaneous R-Parity violation bounds
We investigate bounds from tree-level and one-loop processes in generic
supersymmetric models with spontaneous R-parity breaking in the superpotential.
We analyse the bounds from a general point of view. The bounds are applicable
both for all models with spontaneous R-parity violation and for explicit
bilinear R-parity violation based on general lepton-chargino and
neutrino-neutralino mixings. We find constraints from semileptonic B, D and K
decays, leptonic decays of the mu and tau, electric dipole moments, as well as
bounds for the anomalous magnetic moment of the muon.Comment: 22 page
Neutrino Masses and Mixings from Supersymmetry with Bilinear R--Parity Violation: A Theory for Solar and Atmospheric Neutrino Oscillations
The simplest unified extension of the MSSM with bi-linear R--Parity violation
naturally predicts a hierarchical neutrino mass spectrum, in which one neutrino
acquires mass by mixing with neutralinos, while the other two get mass
radiatively. We have performed a full one-loop calculation of the
neutralino-neutrino mass matrix in the bi-linear \rp MSSM, taking special care
to achieve a manifestly gauge invariant calculation. Moreover we have performed
the renormalization of the heaviest neutrino, needed in order to get meaningful
results. The atmospheric mass scale and maximal mixing angle arise from
tree-level physics, while solar neutrino scale and oscillations follow from
calculable one-loop corrections. If universal supergravity assumptions are made
on the soft-supersymmetry breaking terms then the atmospheric scale is
calculable as a function of a single \rp violating parameter by the
renormalization group evolution due to the non-zero bottom quark Yukawa
coupling. The solar neutrino problem must be accounted for by the small mixing
angle (SMA) MSW solution. If these assumptions are relaxed then one can
implement large mixing angle solutions, either MSW or just-so. The theory
predicts the lightest supersymmetic particle (LSP) decay to be observable at
high-energy colliders, despite the smallness of neutrino masses indicated by
experiment. This provides an independent way to test this solution of the
atmospheric and solar neutrino anomalies.Comment: 46 pages, references added + several misprints correcte
- …