44 research outputs found
De Mandatory Disclosure Richtlijn: beschrijving en kritische analyse
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Global Studies of the Mass, Energy and Angular Distributions in the 200 MeV 4-He + 28-Si Reaction
This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440
A Global Study of the p+27-Al Reaction at 180 MeV
This work was supported by the National Science Foundation Grant NSF PHY 81-14339 and by Indiana Universit
Constructing Entanglement Witness Via Real Skew-Symmetric Operators
In this work, new types of EWs are introduced. They are constructed by using
real skew-symmetric operators defined on a single party subsystem of a
bipartite dxd system and a maximal entangled state in that system. A canonical
form for these witnesses is proposed which is called canonical EW in
corresponding to canonical real skew-symmetric operator. Also for each possible
partition of the canonical real skew-symmetric operator corresponding EW is
obtained. The method used for dxd case is extended to d1xd2 systems. It is
shown that there exist Cd2xd1 distinct possibilities to construct EWs for a
given d1xd2 Hilbert space. The optimality and nd-optimality problem is studied
for each type of EWs. In each step, a large class of quantum PPT states is
introduced. It is shown that among them there exist entangled PPT states which
are detected by the constructed witnesses. Also the idea of canonical EWs is
extended to obtain other EWs with greater PPT entanglement detection power.Comment: 40 page
Conversion of natural forest results in a significant degradation of soil hydraulic properties in the highlands of Kenya
Land use change, especially conversion of native forests can have large impacts on water resources. Large scale conversion of native forests to agricultural land has occurred in the last few decades in the Mau Forest region. To quantify and understand landscape hydrologic responses, this study aimed at evaluating the effects of land use on soil infiltration, saturated hydraulic conductivity, bulk density, sorptivity, and soil moisture retention. A total of 136 plots representing five different land uses (native forest: n = 39, forest plantations: n = 14, tea plantations: n = 24, croplands: n = 23 and pasture: n = 36) were sampled in three catchments with similar parental material in the Mau Forest region, Western Kenya. Native forest topsoils (0â5 cm) had a bulk density of 1.0 ± 0.2 g cmâ3 which was similar to values found for topsoils of forest plantations (1.1 ± 0.2 g cmâ3), but significantly lower than topsoils from croplands (1.4 ± 0.2 g cmâ3), tea plantation (1.3 ± 0.3 g cmâ3) and pastures (1.4 ± 0.2 g cmâ3). Similarly, soil infiltration rates were higher in native forest (76.1 ± 50 cm hâ1) and in forest plantation (60.2 ± 47.9 cm hâ1) than in croplands (40.5 ± 21.5 cm hâ1), tea plantations (43.3 ± 29.2 cm hâ1) and pastures (13.8 ± 14.6 cm hâ1). Native forest had the highest topsoil organic carbon contents (8.11 ± 2.42%) and field capacity (0.62 ±0.12 cm3 cmâ3), while the highest permanent wilting point was recorded for pasture soils (mean of 0.41 ± 0.06 cm cmâ3). The highest plant available water capacity was recorded for soils in native forest (mean of 0.27 ± 0.14 cm cmâ3). Our study indicates that land use changes result in a significant degradation of soil hydraulic properties, which has likely resulted in changes of the regional water balance. Given the magnitude in which managed land use types have changed infiltration rates in our study area, we conclude that changes in land use types occurring in our study region in the last decades have already affected the hydrological regime of the landscapes and the compositions of flow components. The reduction in infiltration and hydraulic conductivity could result in increased surface run-off, erosion and frequency of flooding events
Islands of linkage in an ocean of pervasive recombination reveals two-speed evolution of human cytomegalovirus genomes
Human cytomegalovirus (HCMV) infects most of the population worldwide, persisting throughout the host's life in a latent state with periodic episodes of reactivation. While typically asymptomatic, HCMV can cause fatal disease among congenitally infected infants and immunocompromised patients. These clinical issues are compounded by the emergence of antiviral resistance and the absence of an effective vaccine, the development of which is likely complicated by the numerous immune evasins encoded by HCMV to counter the host's adaptive immune responses, a feature that facilitates frequent super-infections. Understanding the evolutionary dynamics of HCMV is essential for the development of effective new drugs and vaccines. By comparing viral genomes from uncultivated or low-passaged clinical samples of diverse origins, we observe evidence of frequent homologous recombination events, both recent and ancient, and no structure of HCMV genetic diversity at the whole-genome scale. Analysis of individual gene-scale loci reveals a striking dichotomy: while most of the genome is highly conserved, recombines essentially freely and has evolved under purifying selection, 21 genes display extreme diversity, structured into distinct genotypes that do not recombine with each other. Most of these hyper-variable genes encode glycoproteins involved in cell entry or escape of host immunity. Evidence that half of them have diverged through episodes of intense positive selection suggests that rapid evolution of hyper-variable loci is likely driven by interactions with host immunity. It appears that this process is enabled by recombination unlinking hyper-variable loci from strongly constrained neighboring sites. It is conceivable that viral mechanisms facilitating super-infection have evolved to promote recombination between diverged genotypes, allowing the virus to continuously diversify at key loci to escape immune detection, while maintaining a genome optimally adapted to its asymptomatic infectious lifecycle
Many body physics from a quantum information perspective
The quantum information approach to many body physics has been very
successful in giving new insight and novel numerical methods. In these lecture
notes we take a vertical view of the subject, starting from general concepts
and at each step delving into applications or consequences of a particular
topic. We first review some general quantum information concepts like
entanglement and entanglement measures, which leads us to entanglement area
laws. We then continue with one of the most famous examples of area-law abiding
states: matrix product states, and tensor product states in general. Of these,
we choose one example (classical superposition states) to introduce recent
developments on a novel quantum many body approach: quantum kinetic Ising
models. We conclude with a brief outlook of the field.Comment: Lectures from the Les Houches School on "Modern theories of
correlated electron systems". Improved version new references adde
Green function techniques in the treatment of quantum transport at the molecular scale
The theoretical investigation of charge (and spin) transport at nanometer
length scales requires the use of advanced and powerful techniques able to deal
with the dynamical properties of the relevant physical systems, to explicitly
include out-of-equilibrium situations typical for electrical/heat transport as
well as to take into account interaction effects in a systematic way.
Equilibrium Green function techniques and their extension to non-equilibrium
situations via the Keldysh formalism build one of the pillars of current
state-of-the-art approaches to quantum transport which have been implemented in
both model Hamiltonian formulations and first-principle methodologies. We offer
a tutorial overview of the applications of Green functions to deal with some
fundamental aspects of charge transport at the nanoscale, mainly focusing on
applications to model Hamiltonian formulations.Comment: Tutorial review, LaTeX, 129 pages, 41 figures, 300 references,
submitted to Springer series "Lecture Notes in Physics
An Autonomous Lunar Geophysical Experiment Package (ALGEP) for future space missions
Geophysical observations will provide key information about the inner structure of the planets and satellites and understanding the internal structure is a strong constraint on the bulk composition and thermal evolution of these bodies. Thus, geophysical observations are a key to uncovering the origin and evolution of the Moon. In this article, we propose the development of an autonomous lunar geophysical experiment package, composed of a suite of instruments and a central station with standardized interface, which can be installed on various future lunar missions. By fixing the interface between instruments and the central station, it would be possible to easily configure an appropriate experiment package for different missions. We describe here a series of geophysical instruments that may be included as part of the geophysical package: a seismometer, a magnetometer, a heat flow probe, and a laser reflector. These instruments will provide mechanical, thermal, and geodetic parameters of the Moon that are strongly related to the internal structure. We discuss the functionality required for future geophysical observations of the Moon, including the development of the central station that will be used commonly by different payloads
De invloed van het Europese recht op het formele belastingrecht anno 2019
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