2,713 research outputs found

    Vegetation mapping of Žumberak – Samoborsko gorje Nature Park, Croatia, using Landsat 7 and field data

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    A vegetation map of @umberak – Samoborsko gorje Nature Park with a minimum mapping unit of 2.25 ha (22500m2) was created during 2003. ALandsat ETM+ satellite image (acquired in the year 2000) and the results of field sampling were combined as mapping method. Given the constraints of the minimum mapping unit chosen, 17 classes were identified in the field and designated to corresponding polygons created by the classification of satellite image. Thirteen classes were plant communities or their combinations, while remaining four denoted various types of land cover (coniferous plantations, mixed rural landscapes, settlements and quarries). In the overall area of the Nature Park (344 km2), the most frequent type of cover was Lamio orvalae – Fagetum forest (38.4%of total area), while the most frequent non-forest community was Bromo – Plantaginetum mediae (7.9%). According to this research, as much as 77.3%of Park area is covered with forest, which is a significant increase compared to the old data of 61 % of forests. Analyses of mapped polygons showed that almost a quarter of all polygons has an area equal to, or just little bigger than the minimum mapping unit, while more than three quarters of all polygons have their area smaller or equal to 9 ha (corresponds to 300 x 300 meters square). Such an extreme mosaic landscape structure in conjunction with the constant depopulation of Park area causes further natural forestation of park and hence decreases in biodiversity. The overall accuracy of map was 65%, forest vegetation being mapped with higher accuracy (70%) than non-forest vegetation (61%)

    Cu(I) Controls Conformational States in Human Atox1 Metallochaperone: An EPR and Multiscale Simulation Study

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    Atox1 is a human copper metallochaperone that is responsible for transferring copper ions from the main human copper transporter, hCtr1, to ATP7A/B in the Golgi apparatus. Atox1 interacts with the Ctr1 C-terminal domain as a dimer, although it transfers the copper ions to ATP7A/B in a monomeric form. The copper binding site in the Atox1 dimer involves Cys12 and Cys15, while Lys60 was also suggested to play a role in the copper binding. We recently showed that Atox1 can adopt various conformational states, depending on the interacting protein. In the current study, we apply EPR experiments together with hybrid quantum mechanics-molecular mechanics molecular dynamics simulations using a recently developed semiempirical density functional theory approach, to better understand the effect of Atox1's conformational states on copper coordination. We propose that the flexibility of Atox1 occurs owing to protonation of one or more of the cysteine residues, and that Cys15 is an important residue for Atox1 dimerization, while Cys12 is a critical residue for Cu(I) binding. We also show that Lys60 electrostatically stabilizes the Cu(I)-Atox1 dimer

    Exposome and unhealthy aging: environmental drivers from air pollution to occupational exposures

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    The aging population worldwide is facing a significant increase in age-related non-communicable diseases, including cardiovascular and brain pathologies. This comprehensive review paper delves into the impact of the exposome, which encompasses the totality of environmental exposures, on unhealthy aging. It explores how environmental factors contribute to the acceleration of aging processes, increase biological age, and facilitate the development and progression of a wide range of age-associated diseases. The impact of environmental factors on cognitive health and the development of chronic age-related diseases affecting the cardiovascular system and central nervous system is discussed, with a specific focus on Alzheimer’s disease, Parkinson’s disease, stroke, small vessel disease, and vascular cognitive impairment (VCI). Aging is a major risk factor for these diseases. Their pathogenesis involves cellular and molecular mechanisms of aging such as increased oxidative stress, impaired mitochondrial function, DNA damage, and inflammation and is influenced by environmental factors. Environmental toxicants, including ambient particulate matter, pesticides, heavy metals, and organic solvents, have been identified as significant contributors to cardiovascular and brain aging disorders. These toxicants can inflict both macro- and microvascular damage and many of them can also cross the blood–brain barrier, inducing neurotoxic effects, neuroinflammation, and neuronal dysfunction. In conclusion, environmental factors play a critical role in modulating cardiovascular and brain aging. A deeper understanding of how environmental toxicants exacerbate aging processes and contribute to the pathogenesis of neurodegenerative diseases, VCI, and dementia is crucial for the development of preventive strategies and interventions to promote cardiovascular, cerebrovascular, and brain health. By mitigating exposure to harmful environmental factors and promoting healthy aging, we can strive to reduce the burden of age-related cardiovascular and brain pathologies in the aging population

    A trapped single ion inside a Bose-Einstein condensate

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    Improved control of the motional and internal quantum states of ultracold neutral atoms and ions has opened intriguing possibilities for quantum simulation and quantum computation. Many-body effects have been explored with hundreds of thousands of quantum-degenerate neutral atoms and coherent light-matter interfaces have been built. Systems of single or a few trapped ions have been used to demonstrate universal quantum computing algorithms and to detect variations of fundamental constants in precision atomic clocks. Until now, atomic quantum gases and single trapped ions have been treated separately in experiments. Here we investigate whether they can be advantageously combined into one hybrid system, by exploring the immersion of a single trapped ion into a Bose-Einstein condensate of neutral atoms. We demonstrate independent control over the two components within the hybrid system, study the fundamental interaction processes and observe sympathetic cooling of the single ion by the condensate. Our experiment calls for further research into the possibility of using this technique for the continuous cooling of quantum computers. We also anticipate that it will lead to explorations of entanglement in hybrid quantum systems and to fundamental studies of the decoherence of a single, locally controlled impurity particle coupled to a quantum environment

    Extraction of the Electron Self-Energy from Angle Resolved Photoemission Data: Application to Bi2212

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    The self-energy Σ(k,ω)\Sigma({\bf k},\omega), the fundamental function which describes the effects of many-body interactions on an electron in a solid, is usually difficult to obtain directly from experimental data. In this paper, we show that by making certain reasonable assumptions, the self-energy can be directly determined from angle resolved photoemission data. We demonstrate this method on data for the high temperature superconductor Bi2Sr2CaCu2O8+xBi_2Sr_2CaCu_2O_{8+x} (Bi2212) in the normal, superconducting, and pseudogap phases.Comment: expanded version (6 pages), to be published, Phys Rev B (1 Sept 99

    Magnetic properties of X-Pt (X=Fe,Co,Ni) alloy systems

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    We have studied the electronic and magnetic properties of Fe-Pt, Co-Pt and Ni-Pt alloy systems in ordered and disordered phases. The influence of various exchange-correlation functionals on values of equilibrium lattice parameters and magnetic moments in ordered Fe-Pt, Co-Pt and Ni-Pt alloys have been studied using linearized muffin-tin orbital method. The electronic structure calculations for the disordered alloys have been carried out using augmented space recursion technique in the framework of tight binding linearized muffin-tin orbital method. The effect of short range order has also been studied in the disordered phase of these systems. The results show good agreements with available experimental values.Comment: 21 pages, 4 eps figures, accepted for publication in Journal of Physics Condensed Matte

    Loop quantum gravity: the first twenty five years

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    This is a review paper invited by the journal "Classical ad Quantum Gravity" for a "Cluster Issue" on approaches to quantum gravity. I give a synthetic presentation of loop gravity. I spell-out the aims of the theory and compare the results obtained with the initial hopes that motivated the early interest in this research direction. I give my own perspective on the status of the program and attempt of a critical evaluation of its successes and limits.Comment: 24 pages, 3 figure

    Single-Shot Electron Imaging of Dopant-Induced Nanoplasmas

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    We present single-shot electron velocity-map images of nanoplasmas generated from doped helium nanodroplets and neon clusters by intense near-infrared and mid-infrared laser pulses. We report a large variety of signal types, most crucially depending on the cluster size. The common feature is a two-component distribution for each single-cluster event: a bright inner part with nearly circular shape corresponding to electron energies up to a few eV, surrounded by an extended background of more energetic electrons. The total counts and energy of the electrons in the inner part are strongly correlated and follow a simple power-law dependence. Deviations from the circular shape of the inner electrons observed for neon clusters and large helium nanodroplets indicate non-spherical shapes of the neutral clusters. The dependence of the measured electron energies on the extraction voltage of the spectrometer indicates that the evolution of the nanoplasma is significantly affected by the presence of an external electric field. This conjecture is confirmed by molecular dynamics simulations, which reproduce the salient features of the experimental electron spectra.The authors are grateful for financial support from the Deutsche Forschungsgemeinschaft (DFG) within the project MU 2347/12-1 and STI 125/22-2 in the frame of the Priority Programme 1840 ‘Quantum Dynamics in Tailored Intense Fields’, from the Carlsberg Foundation and the SPARC Programme, MHRD, India. The ELI-ALPS Project (GINOP-2.3.6-15-2015-00001) is supported by the European Union and co-financed by the European Regional Development Fund. AH is grateful for financial support from the Basque Government (Project Reference No. IT1254-19) and from the Spanish Ministerio de Economia y Competividad (Reference No. CTQ2015-67660-P). Computational and manpower support provided by IZO-SGI SG Iker of UPV/EHU and European funding (EDRF and ESF) is gratefully acknowledged

    Thermal plasma synthesis of Li2S nanoparticles for application in lithium-sulfur batteries

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    Abstract : Inductively-coupled thermal plasma processes were used to produce nanosized Li2S. Prior to the syntheses, the feasibility of forming Li2S was first evaluated using FactSage by considering the phase diagrams of sulfur and different lithium precursors in reducing atmospheres; Li2O, LiOH·H2O, Li2CO3 and Li2SO4·H2O all showed promises in producing Li2S nanoparticles, as confirmed by experiments. Argon and hydrogen mixtures were used as plasma gases, and a carbothermal reduction was implemented for Li2SO4·H2O. In addition, carbon-coated Li2S nanoparticles were synthesized with downstream injection of methane. Carbon was shown to stabilize Li2S upon contact with ambient air. The Li2S nanoparticles were electrochemically tested in half-cells using electrolytes containing LiNO3 or Li2S6 as additives. It was found that adding LiNO3 to the electrolyte was detrimental to the electrochemical performance of Li2S, whereas the combination of Li2S6 and LiNO3 as additives doubled the charge and discharge capacities of the half-cell over 10 cycles
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