598 research outputs found
One-neutron halo structure by the ratio method
We present a new observable to study halo nuclei. This new observable is a
particular ratio of angular distributions for elastic breakup and scattering.
For one-neutron halo nuclei, it is shown to be independent of the reaction
mechanism and to provide significant information about the structure of the
projectile, including binding energy, partial-wave configuration, and radial
wave function of the halo. This observable offers new capabilities for the
study of nuclear structure far from stability.Comment: 9 pages, 4 figure
B(E1) Strengths from Coulomb Excitation of 11Be
The (E1;) strength for Be has been extracted from
intermediate energy Coulomb excitation measurements, over a range of beam
energies using a new reaction model, the extended continuum discretized coupled
channels (XCDCC) method. In addition, a measurement of the excitation cross
section for Be+Pb at 38.6 MeV/nucleon is reported. The (E1)
strength of 0.105(12) efm derived from this measurement is consistent
with those made previously at 60 and 64 MeV/nucleon, i n contrast to an
anomalously low result obtained at 43 MeV/nucleon. By coupling a
multi-configuration description of the projectile structure with realistic
reaction theory, the XCDCC model provides for the first time a fully quantum
mechanical description of Coulomb excitation. The XCDCC calculations reveal
that the excitation process involves significant contributions from nuclear,
continuum, and higher-order effects. An analysis of the present and two earlier
intermediate energy measurements yields a combined B(E1) strength of 0.105(7)
efm. This value is in good agreement with the value deduced
independently from the lifetime of the state in Be, and has a
comparable p recision.Comment: 5 pages, 2 figures, accepted for publication in Phys. Lett.
Role of magnetic anisotropy on the magnetic properties of Ni nanoclusters embedded in a ZnO matrix
We have investigated the magnetic properties of Ni nanoaggregates produced by ion implantation in ZnO single crystals. Several deviations from classical models usually adopted to describe the magnetic properties of nanoparticle systems were found. The strain between host and Ni nanoaggregates induces a magnetic anisotropy with a preferred direction. We show that these anisotropy effects can be misinterpreted as a ferromagnetic or antiferromagnetic coupling among the nanoaggregates similar to that of an oriented, interacting nanocrystal ensemble
The state of the dark energy equation of state circa 2023
We critically examine the state of current constraints on the dark energy (DE) equation of state (EoS) w. Our study is motivated by the observation that, while broadly consistent with the cosmological constant value w = -1, several independent probes appear to point towards a slightly phantom EoS (w ∼ -1.03) which, if confirmed, could have important implications for the Hubble tension. We pay attention to the apparent preference for phantom DE from Planck Cosmic Microwave Background (CMB) data alone, whose origin we study in detail and attribute to a wide range of (physical and geometrical) effects. We deem the combination of Planck CMB, Baryon Acoustic Oscillations, Type Ia Supernovae, and Cosmic Chronometers data to be particularly trustworthy, inferring from this final consensus dataset w = -1.013+0.038-0.043, in excellent agreement with the cosmological constant value. Overall, despite a few scattered hints, we find no compelling evidence forcing us away from the cosmological constant (yet)
Exploring new physics in the late Universe’s expansion through non-parametric inference
In this study, we investigate deviations from the
Planck-CDM model in the late universe (z 2.5) using
the Gaussian Processes method, with minimal assumptions.
Our goal is to understand where exploring new physics in
the late universe is most relevant. We analyze recent Cosmic
Chronometers (CC), Type Ia Supernovae (SN), and Baryon
Acoustic Oscillations (BAO) data. By examining reconstructions of the dimensionless parameter δ(z), which measures
deviations of the Hubble parameter from the Planck-CDM
predictions, we identify intriguing features at low (z 0.5)
and high (z 2) redshifts. Deviations from the Planck-
CDM model were not significant between 0.5 z 2.
Using the combined CC+SN+BAO dataset, we gain insights
into dark energy (DE) dynamics, resembling characteristics
of omnipotent DE, extending beyond quintessence and phantom models. DE exhibits n-quintessence traits for z 2,
transitioning with a singularity around z ∼ 2 to usual phantom traits in 1 z 2. DE characteristics differ between
scenarios (H0-SH0ES and H0-&CMB), with H0-SH0ES
leaning towards phantom traits and H0-&CMB towards
quintessence. We suggest exploring new physics at z 0.5
and 1.5 z 2.5, particularly around z = 2, to understand
cosmological tensions such as H0 and S
Imbalance of naive and memory T lymphocytes with sustained high cellular activation during the first year of life from uninfected children born to HIV-1-infected mothers on HAART
The immune consequences of in utero HIV exposure to uninfected children whose mothers were submitted to highly active antiretroviral therapy (HAART) during gestation are not well defined. We evaluated 45 HIV-exposed uninfected (ENI) neonates and 45 healthy unexposed control (CT) neonates. All HIV-infected mothers received HAART during pregnancy, and the viral load at delivery was <50 copies/mL for 56.8%. Twenty-three ENI neonates were further evaluated after 12 months and compared to 23 unexposed healthy age-matched infants. Immunophenotyping was performed by flow cytometry in cord and peripheral blood. Cord blood lymphocyte numbers did not differ between groups. However, ENI neonates had a lower percentage of naive T cells than CT neonates (CD4+, 76.6 vs 83.1%, P < 0.001; CD8+, 70.9 vs 79.6%, P = 0.003) and higher percentages of central memory T cells than CT neonates (CD4+, 13.9 vs 8.7%, P < 0.001; CD8+, 8.6 vs 4.8%, P = 0.001). CD38 mean fluorescence intensity of T cells was higher in ENI neonates (CD4+, 62.2 vs 52.1, P = 0.007; CD8+, 47.7 vs 35.3, P < 0.001). At 12 months, ENI infants still had higher mean fluorescence intensity of CD38 on T cells (CD4+, 34.2 vs 23.3, P < 0.001; CD8+, 26.8 vs 19.4, P = 0.035). Despite effective maternal virologic control at delivery, HIV-exposed uninfected children were born with lower levels of naive T cells. Immune activation was present at birth and remained until at least 12 months of age, suggesting that in utero exposure to HIV causes subtle immune abnormalities.FAPESPCoordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES
Levantamento De Raças Do Agente Causador Do Míldio Da Alface No Estado De São Paulo Em 2012 E 2013
Lettuce is, among leafy vegetables, the most economically important one to Brazil. In the winter, at low temperatures and under leaf wetness, downy mildew of lettuce, a disease caused by the etiologic agent Bremia lactucae, occurs in almost all regions where this vegetable is grown and is considered one of the most severe foliar diseases for the culture. The aim of this study was to identify the races of B. lactucae in 2012 and 2013 that occurred in the main producing regions of São Paulo State, such as: Ribeirão Preto, Jaboticabal, Pirangi, Catanduva, São José do Rio Preto, Atibaia, Salesópolis, Biritiba Mirim, Mogi das Cruzes, Campinas, Itapira, Mogi Mirim, Cândido Mota, Presidente Prudente, Echaporã, Assis, Marilia, Botucatu and Bauru. During the months of July/August 2012 and 2013, we collected samples of lettuce leaves showing symptoms of downy mildew, and in each collected sample the pathogen structures referred to an isolate. The sporangia were multiplied on the susceptible cultivar Solaris, with subsequent inoculation in differential cultivars, performing evaluations on the 12th day from the appearance of the first sporulation in the susceptible cultivar ‘Green Tower’ (Dm-0), according to the code “Sextet”. In 2012, two new codes were determined, identifying two new races, SPBl:10 (63/31/02/00) and SPBl:11 (63/63/18/00). In 2013, a new codification was determined (63/31/18/00), to which the name SPBl:12 was proposed. The genes Dm-14 and Dm-15 and the resistance factors FR-17, FR-18, FR-36, FR-37 and FR-38 confer resistance to these new races that were identified. It is recommended, therefore, in breeding programs of lettuce, the use of factors FR-17, FR-18 and FR-38 as sources of resistance for new cultivars developed in the state of São Paulo, because they confer resistance to all 12 already identified races. © 2016, Universidade Estadual Paulista (UNESP). All Rights Reserved.421535
A consistent view of interacting dark energy from multiple CMB probes
We analyze a cosmological model featuring an interaction between dark energy and dark matter in light of the measurements of the Cosmic Microwave Background released by three independent experiments: the most recent data by the Planck satellite and the Atacama Cosmology Telescope, and WMAP (9-year data). We show that different combinations of the datasets provide similar results, always favoring an interacting dark sector with a 95% C.L. significance in the majority of the cases. Remarkably, such a preference remains consistent when cross-checked through independent probes, while always yielding a value of the expansion rate H0 consistent with the local distance ladder measurements. We investigate the source of this preference by scrutinizing the angular power spectra of temperature and polarization anisotropies as measured by different experiments
A dorsal fold in Gymnura micrura (Bloch and Scheneider, 1801) (Chondrichthyes: Gymnuridae)
Agricultural contamination: Effect of copper excess on physiological parameters of potato genotypes and food chain security
Areas with a history of cupric fungicide application accumulate copper (Cu), which may be toxic to plants and might result in food chain contamination. This work aimed to study the effects of Cu contaminated vineyard soils (2.2, 5, 36.3, 67, 95.7, 270.5 and 320.70 mg Cu kg-1 soil) on potato physiology and it´s potential risk to human health, during the fall and spring growing seasons. The increase of Cu concentration in leaves was dependent on external Cu concentrations and development stage of the leaves. There were genotypic differences for both growth and biochemical parameters including high accumulation of Cu in tubers among the genotypes. Therefore, Cu stress triggered a defense mechanism against oxidative stress in potato plants; and the magnitude of Cu stress was depended on the genotype and the plant physiological status. In addition, these results provide evidence that potato antioxidants are not sufficient to prevent biological damage caused by Cu toxicity, and that popato cultivation in areas with high Cu levels is not recommended due to low production and potential risk to human health
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