M1 Resonances in Unstable Magic Nuclei

Within a microscopic approach which takes into account RPA configurations, the single-particle continuum and more complex $1p1h\otimes phonon$ configurations isoscalar and isovector M1 excitations for the unstable nuclei ${56,78}$Ni and ${100,132}$Sn are calculated. For comparison, the experimentally known M1 excitations in ${40}$Ca and $^{208}$Pb have also been calculated. In the latter nuclei good agreement in the centroid energy, the total transition strength and the resonance width is obtained. With the same parameters we predict the magnetic excitations for the unstable nuclei. The strength is sufficiently concentrated to be measurable in radioactive beam experiments. New features are found for the very neutron rich nucleus ${78}$Ni and the neutron deficient nucleus ${100}$Sn.Comment: 17 pages (LATEX), 12 figures (available from the authors), KFA-IKP(TH)-1993-0

Recent advances in neutrinoless double beta decay search

Even after the discovery of neutrino flavour oscillations, based on data from atmospheric, solar, reactor, and accelerator experiments, many characteristics of the neutrino remain unknown. Only the neutrino square-mass differences and the mixing angle values have been estimated, while the value of each mass eigenstate still hasn't. Its nature (massive Majorana or Dirac particle) is still escaping. Neutrinoless double beta decay ($0\nu$-DBD) experimental discovery could be the ultimate answer to some delicate questions of elementary particle and nuclear physics. The Majorana description of neutrinos allows the $0\nu$-DBD process, and consequently either a mass value could be measured or the existence of physics beyond the standard should be confirmed without any doubt. As expected, the $0\nu$-DBD measurement is a very difficult field of application for experimentalists. In this paper, after a short summary of the latest results in neutrino physics, the experimental status, the R&D projects, and perspectives in $0\nu$-DBD sector are reviewed.Comment: 36 pages, 7 figures, To be publish in Czech Journal of Physic

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time, and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space. While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes, vast areas of the tropics remain understudied. In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity, but it remains among the least known forests in America and is often underrepresented in biodiversity databases. To worsen this situation, human-induced modifications may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge, it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

The global distribution and drivers of wood density and their impact on forest carbon stocks.

The density of wood is a key indicator of the carbon investment strategies of trees, impacting productivity and carbon storage. Despite its importance, the global variation in wood density and its environmental controls remain poorly understood, preventing accurate predictions of global forest carbon stocks. Here we analyse information from 1.1 million forest inventory plots alongside wood density data from 10,703 tree species to create a spatially explicit understanding of the global wood density distribution and its drivers. Our findings reveal a pronounced latitudinal gradient, with wood in tropical forests being up to 30% denser than that in boreal forests. In both angiosperms and gymnosperms, hydrothermal conditions represented by annual mean temperature and soil moisture emerged as the primary factors influencing the variation in wood density globally. This indicates similar environmental filters and evolutionary adaptations among distinct plant groups, underscoring the essential role of abiotic factors in determining wood density in forest ecosystems. Additionally, our study highlights the prominent role of disturbance, such as human modification and fire risk, in influencing wood density at more local scales. Factoring in the spatial variation of wood density notably changes the estimates of forest carbon stocks, leading to differences of up to 21% within biomes. Therefore, our research contributes to a deeper understanding of terrestrial biomass distribution and how environmental changes and disturbances impact forest ecosystems

An alternative method to determine 235U in environmental samples

In this work, three different procedures (direct gamma-ray spectroscopy, indirect gamma-ray spectroscopy and gamma-gamma coincident spectroscopy) are employed in the determination of the amount of 235U in a well-known enriched-Uranium sample, and all three are discussed as possible alternatives to determine 235U in environmental samples. The results show that the three methods give similar results, although these results are all ~30% below the expected value

Conceptual Design of a Personal Aerial Vehicle Using Co- Flow Jet Airfoil

A flying wing personal aerial vehicle (PAV) is designed using a co-flow jet airfoil (CFJ); it is designed to take-off and land on regular roads and highways, at take-off speed of 60mph. The advantages of using CFJ throughout the entire PAV are the enhanced lift/stall margin and thrust generation. It has a targeted range of 500miles, at a cruise mach number of 0.3 at an altitude of 10,000ft with a payload of 3 passengers. The aspect ratio achieved is 2.5 with the addition of an elliptical wing to increase the wing span of the PAV. The mass flow of the jet that covers the surface of the wings needed is of 19kg/s, requiring a power of 684hp (510kW) to pump the jets to such mass flow rate. Given these conditions, the CFD analysis is still in progress. Nomenclature AR = aspect ratio b = wing span s = wing area PR = total pressure ratio m & = mass flow rate U = velocity V = velocity C m = momentum coefficient ρ = density γ = ratio of specific heats I

{beta}{sup +} Decay and Cosmic-Ray Half-Lives of {sup 143}Pm and {sup 144}Pm

The positron decay partial half-lives of {sup 143}Pm and {sup 144}Pm are needed to assess the viability of elemental Pm as a cosmic-ray clock. We have conducted experiments to measure the {beta}{sup +} branches of these isotopes; we find {beta}{sup +} branches of these isotopes; we find {beta}{sup +} branches of <5.7 {times}10{sup {minus}8} for {sup 143}Pm and <8{times}10{sup {minus} 7} for {sup 144}Pm. Through these branches are a factor of 20 lower than the previous experimental limits, the resulting partial half-lives are still too uncertain to permit any firm conclusions