42 research outputs found
Neutrino masses and mixing parameters in a left-right model with mirror fermions
In this work we consider a left-right model containing mirror fermions with
gauge group SU(3). The model has several free parameters which here we have
calculated by using the recent values for the squared-neutrino mass
differences. Lower bound for the mirror vacuum expectation value helped us to
obtain crude estimations for some of these parameters. Also we estimate the
order of magnitude of the masses of the standard and mirror neutrinos.Comment: 13 pages, version submitted to European Physical Journal
New Higgs signals induced by mirror fermion mixing effects
We study the conditions under which flavor violation arises in scalar-fermion
interactions, as a result of the mixing phenomena between the standard model
and exotic fermions. Phenomenological consequences are discussed within the
specific context of a left-right model where these additional fermions have
mirror properties under the new SU(2)_R gauge group.
Bounds on the parameters of the model are obtained from LFV processes; these
results are then used to study the LFV Higgs decays (H --> tau l_j, l_j = e,
mu), which reach branching ratios that could be detected at future colliders.Comment: 12 pages, 2 figures, ReVTex4, graphicx, to be published in Phys. Rev.
Lepton mass generation and family number violation mechanism in the model
Lepton family number violation processes arise in the model due to the presence of an extra neutral gauge boson, Z, with
family changing couplings, and due to the fact that this model demands the
existence of heavy exotic leptons. The mixing of the standard Z with Z and
the mixing of ordinary leptons with exotic ones induce together family changing
couplings on the Z and therefore nonvanishing rates for lepton family number
violation processes, such as , and . Additional contributions to the processes and
are induced from the mass generation mechanism. This last
type of contributions may compete with the above one, depending on the masses
of the scalars which participate in the diagrams which generate radiatively the
masses of the charged leptons. Using the experimental data we compute some
bounds for the mixings parameters and for the masses of the scalars.Comment: 12 pages, Latex, 7 figures. Accepted for publication in Int. Journ.
of Mod. Phys.
EstadĂsticas e Indicadores de la Universidad Nacional de Colombia 2002
PresentaciĂłn Capitulo 1. Temas de debate: Bases para una polĂtica acadĂ©mica de la Universidad Nacional de Colombia Capitulo 2. ConstrucciĂłn de visibilidad: cifras y anĂĄlisis Capitulo 2.1A. FilosofĂa, organizaciĂłn y resultados del programa Universidad Virtual de la Universidad Nacional de Colombia Capitulo 2.1B. FilosofĂa, organizaciĂłn y resultados del programa Universidad Virtual de la Universidad Nacional de Colombia Capitulo 2.1C. FilosofĂa, organizaciĂłn y resultados del programa Universidad Virtual de la Universidad Nacional de Colombia Capitulo 2.2A. La evaluaciĂłn de la extensiĂłn universitaria y la construcciĂłn de pertinencia social de la universidad Capitulo 2.2B. La evaluaciĂłn de la extensiĂłn universitaria y la construcciĂłn de pertinencia social de la universidad Capitulo 3. Contextos Capitulo 3.1A. Internacionalizar la Universidad Nacional de Colombia Capitulo 3.2A. Equidad en el acceso a la Universidad Nacional de Colombia: programas de admisiĂłn especial Capitulo 3.2B. Equidad en el acceso a la Universidad Nacional de Colombia: programas de admisiĂłn especial Capitulo 4.A. Indicadores de GestiĂłn: los indicadores de la lĂnea objetivo Capitulo 4.B. Indicadores de GestiĂłn: los indicadores de la lĂnea objetivo Capitulo 4.C. Indicadores de GestiĂłn: los indicadores de la lĂnea objetivo Capitulo 4.D. Indicadores de GestiĂłn: los indicadores de la lĂnea objetivo Capitulo 5. InformaciĂłn estadĂstica Capitulo 5.A. Indicadores bĂĄsicos Capitulo 5.B. EstadĂsticas de Inscritos y admitidos Capitulo 5.C. EstadĂsticas de estudiantes matriculados Capitulo 5.D. EstadĂsticas de estudiantes graduados Capitulo 5.E. EstadĂsticas de programas curriculares Capitulo 5.F. EstadĂsticas de talento human
Surface indicators are correlated with soil multifunctionality in global drylands
Multiple ecosystem functions need to be considered simultaneously to manage and protect the several ecosystem services that are essential to people and their environments. Despite this, cost effective, tangible, relatively simple and globally relevant methodologies to monitor in situ soil multifunctionality, that is, the provision of multiple ecosystem functions by soils, have not been tested at the global scale. We combined correlation analysis and structural equation modelling to explore whether we could find easily measured, field-based indicators of soil multifunctionality (measured using functions linked to the cycling and storage of soil carbon, nitrogen and phosphorus). To do this, we gathered soil data from 120 dryland ecosystems from five continents. Two soil surface attributes measured in situ (litter incorporation and surface aggregate stability) were the most strongly associated with soil multifunctionality, even after accounting for geographic location and other drivers such as climate, woody cover, soil pH and soil electric conductivity. The positive relationships between surface stability and litter incorporation on soil multifunctionality were greater beneath the canopy of perennial vegetation than in adjacent, open areas devoid of vascular plants. The positive associations between surface aggregate stability and soil functions increased with increasing mean annual temperature. Synthesis and applications. Our findings demonstrate that a reduced suite of easily measured in situ soil surface attributes can be used as potential indicators of soil multifunctionality in drylands world-wide. These attributes, which relate to plant litter (origin, incorporation, cover), and surface stability, are relatively cheap and easy to assess with minimal training, allowing operators to sample many sites across widely varying climatic areas and soil types. The correlations of these variables are comparable to the influence of climate or soil, and would allow cost-effective monitoring of soil multifunctionality under changing land-use and environmental conditions. This would provide important information for evaluating the ecological impacts of land degradation, desertification and climate change in drylands world-wide.Fil: Eldridge, David J.. University of New South Wales; AustraliaFil: Delgado Baquerizo, Manuel. Universidad Rey Juan Carlos; EspañaFil: Quero, JosĂ© L.. Universidad de CĂłrdoba; EspañaFil: Ochoa, Victoria. Universidad Rey Juan Carlos; España. Universidad de Alicante; EspañaFil: Gozalo, Beatriz. Universidad Rey Juan Carlos; España. Universidad de Alicante; EspañaFil: GarcĂa Palacios, Pablo. Universidad Rey Juan Carlos; EspañaFil: Escolar, Cristina. Universidad Rey Juan Carlos; EspañaFil: GarcĂa GĂłmez, Miguel. Universidad PolitĂ©cnica de Madrid; EspañaFil: Prina, AnĂbal. Universidad Nacional de La Pampa; ArgentinaFil: Bowker, Mathew A.. Northern Arizona University; Estados UnidosFil: Bran, Donaldo Eduardo. Instituto Nacional de TecnologĂa Agropecuaria. Centro Regional Patagonia Norte. EstaciĂłn Experimental Agropecuaria San Carlos de Bariloche; ArgentinaFil: Castro, Ignacio. Universidad Experimental SimĂłn RodrĂguez; VenezuelaFil: Cea, Alex. Universidad de La Serena; ChileFil: Derak, Mchich. No especifĂca;Fil: Espinosa, Carlos I.. Universidad TĂ©cnica Particular de Loja; EcuadorFil: Florentino, Adriana. Universidad Central de Venezuela; VenezuelaFil: GaitĂĄn, Juan JosĂ©. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Instituto Nacional de TecnologĂa Agropecuaria. Centro de InvestigaciĂłn de Recursos Naturales. Instituto de Suelos; Argentina. Universidad Nacional de LujĂĄn. Departamento de TecnologĂa; ArgentinaFil: Gatica, Mario Gabriel. Universidad Nacional de San Juan. Facultad de Ciencias Exactas FĂsicas y Naturales. Departamento de BiologĂa; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - San Juan. Centro de Investigaciones de la Geosfera y Biosfera. Universidad Nacional de San Juan. Facultad de Ciencias Exactas FĂsicas y Naturales. Centro de Investigaciones de la Geosfera y Biosfera; ArgentinaFil: GĂłmez GonzĂĄlez, Susana. Universidad de CĂĄdiz; EspañaFil: Ghiloufi, Wahida. UniversitĂ© de Sfax; TĂșnezFil: Gutierrez, Julio R.. Universidad de La Serena; ChileFil: Guzman, Elizabeth. Universidad TĂ©cnica Particular de Loja; EcuadorFil: HernĂĄndez, Rosa M.. Universidad Experimental SimĂłn RodrĂguez; VenezuelaFil: Hughes, Frederic M.. Universidade Estadual de Feira de Santana; BrasilFil: Muiño, Walter. Universidad Nacional de La Pampa; ArgentinaFil: Monerris, Jorge. No especifĂca;Fil: Ospina, Abelardo. Universidad Central de Venezuela; VenezuelaFil: RamĂrez, David A.. International Potato Centre; PerĂșFil: Ribas Fernandez, Yanina Antonia. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - San Juan. Centro de Investigaciones de la Geosfera y Biosfera. Universidad Nacional de San Juan. Facultad de Ciencias Exactas FĂsicas y Naturales. Centro de Investigaciones de la Geosfera y Biosfera; ArgentinaFil: RomĂŁo, Roberto L.. Universidade Estadual de Feira de Santana; BrasilFil: Torres DĂaz, Cristian. Universidad del Bio Bio; ChileFil: Koen, Terrance B.. No especifĂca;Fil: Maestre, Fernando T.. Universidad Rey Juan Carlos; España. Universidad de Alicante; Españ
Soil fungal abundance and plant functional traits drive fertile island formation in global drylands
International audience1.Dryland vegetation is characterised by discrete plant patches that accumulate and capture soil resources under their canopies. These âfertile islandsâ are major drivers of dryland ecosystem structure and functioning, yet we lack an integrated understanding of the factors controlling their magnitude and variability at the global scale.2.We conducted a standardized field survey across two hundred and thirty-six drylands from five continents. At each site, we measured the composition, diversity and cover of perennial plants. Fertile island effects were estimated at each site by comparing composite soil samples obtained under the canopy of the dominant plants and in open areas devoid of perennial vegetation. For each sample, we measured fifteen soil variables (functions) associated with carbon, nitrogen and phosphorus cycling and used the Relative Interaction Index to quantify the magnitude of the fertile island effect for each function. In eighty sites, we also measured fungal and bacterial abundance (quantitative PCR) and diversity (Illumina MiSeq).3.The most fertile islands, i.e. those where a higher number of functions were simultaneously enhanced, were found at lower-elevation sites with greater soil pH values and sand content under semiarid climates, particularly at locations where the presence of tall woody species with a low specific leaf area increased fungal abundance beneath plant canopies, the main direct biotic controller of the fertile island effect in the drylands studied. Positive effects of fungal abundance were particularly associated with greater nutrient contents and microbial activity (soil extracellular enzymes) under plant canopies.4.Synthesis. Our results show that the formation of fertile islands in global drylands largely depends on: (i) local climatic, topographic and edaphic characteristics, (ii) the structure and traits of local plant communities and (iii) soil microbial communities. Our study also has broad implications for the management and restoration of dryland ecosystems worldwide, where woody plants are commonly used as nurse plants to enhance the establishment and survival of beneficiary species. Finally, our results suggest that forecasted increases in aridity may enhance the formation of fertile islands in drylands worldwide
The effect of particle size and amount of inoculum on fungal treatment of wheat straw and wood chips
CARB-ES-19 Multicenter Study of Carbapenemase-Producing Klebsiella pneumoniae and Escherichia coli From All Spanish Provinces Reveals Interregional Spread of High-Risk Clones Such as ST307/OXA-48 and ST512/KPC-3
ObjectivesCARB-ES-19 is a comprehensive, multicenter, nationwide study integrating whole-genome sequencing (WGS) in the surveillance of carbapenemase-producing K. pneumoniae (CP-Kpn) and E. coli (CP-Eco) to determine their incidence, geographical distribution, phylogeny, and resistance mechanisms in Spain.MethodsIn total, 71 hospitals, representing all 50 Spanish provinces, collected the first 10 isolates per hospital (February to May 2019); CPE isolates were first identified according to EUCAST (meropenem MIC > 0.12 mg/L with immunochromatography, colorimetric tests, carbapenem inactivation, or carbapenem hydrolysis with MALDI-TOF). Prevalence and incidence were calculated according to population denominators. Antibiotic susceptibility testing was performed using the microdilution method (EUCAST). All 403 isolates collected were sequenced for high-resolution single-nucleotide polymorphism (SNP) typing, core genome multilocus sequence typing (cgMLST), and resistome analysis.ResultsIn total, 377 (93.5%) CP-Kpn and 26 (6.5%) CP-Eco isolates were collected from 62 (87.3%) hospitals in 46 (92%) provinces. CP-Kpn was more prevalent in the blood (5.8%, 50/853) than in the urine (1.4%, 201/14,464). The cumulative incidence for both CP-Kpn and CP-Eco was 0.05 per 100 admitted patients. The main carbapenemase genes identified in CP-Kpn were blaOXAâ48 (263/377), blaKPCâ3 (62/377), blaVIMâ1 (28/377), and blaNDMâ1 (12/377). All isolates were susceptible to at least two antibiotics. Interregional dissemination of eight high-risk CP-Kpn clones was detected, mainly ST307/OXA-48 (16.4%), ST11/OXA-48 (16.4%), and ST512-ST258/KPC (13.8%). ST512/KPC and ST15/OXA-48 were the most frequent bacteremia-causative clones. The average number of acquired resistance genes was higher in CP-Kpn (7.9) than in CP-Eco (5.5).ConclusionThis study serves as a first step toward WGS integration in the surveillance of carbapenemase-producing Enterobacterales in Spain. We detected important epidemiological changes, including increased CP-Kpn and CP-Eco prevalence and incidence compared to previous studies, wide interregional dissemination, and increased dissemination of high-risk clones, such as ST307/OXA-48 and ST512/KPC-3
Multi-messenger Observations of a Binary Neutron Star Merger
On 2017 August 17 a binary neutron star coalescence candidate (later
designated GW170817) with merger time 12:41:04 UTC was observed through
gravitational waves by the Advanced LIGO and Advanced Virgo detectors.
The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray
burst (GRB 170817A) with a time delay of ⌠1.7 {{s}} with respect to
the merger time. From the gravitational-wave signal, the source was
initially localized to a sky region of 31 deg2 at a
luminosity distance of {40}-8+8 Mpc and with
component masses consistent with neutron stars. The component masses
were later measured to be in the range 0.86 to 2.26 {M}ÈŻ
. An extensive observing campaign was launched across the
electromagnetic spectrum leading to the discovery of a bright optical
transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC
4993 (at ⌠40 {{Mpc}}) less than 11 hours after the merger by the
One-Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The
optical transient was independently detected by multiple teams within an
hour. Subsequent observations targeted the object and its environment.
Early ultraviolet observations revealed a blue transient that faded
within 48 hours. Optical and infrared observations showed a redward
evolution over âŒ10 days. Following early non-detections, X-ray and
radio emission were discovered at the transientâs position ⌠9
and ⌠16 days, respectively, after the merger. Both the X-ray and
radio emission likely arise from a physical process that is distinct
from the one that generates the UV/optical/near-infrared emission. No
ultra-high-energy gamma-rays and no neutrino candidates consistent with
the source were found in follow-up searches. These observations support
the hypothesis that GW170817 was produced by the merger of two neutron
stars in NGC 4993 followed by a short gamma-ray burst (GRB 170817A) and
a kilonova/macronova powered by the radioactive decay of r-process
nuclei synthesized in the ejecta.</p