187 research outputs found
Improved DIQKD protocols with finite-size analysis
The security of finite-length keys is essential for the implementation of
device-independent quantum key distribution (DIQKD). Presently, there are
several finite-size DIQKD security proofs, but they are mostly focused on
standard DIQKD protocols and do not directly apply to the recent improved DIQKD
protocols based on noisy preprocessing, random key measurements, and modified
CHSH inequalities. Here, we provide a general finite-size security proof that
can simultaneously encompass these approaches, using tighter finite-size bounds
than previous analyses. In doing so, we develop a method to compute tight lower
bounds on the asymptotic keyrate for any such DIQKD protocol with binary inputs
and outputs. With this, we show that positive asymptotic keyrates are
achievable up to depolarizing noise values of , exceeding all
previously known noise thresholds. We also develop a modification to
random-key-measurement protocols, using a pre-shared seed followed by a "seed
recovery" step, which yields substantially higher net key generation rates by
essentially removing the sifting factor. Some of our results may also improve
the keyrates of device-independent randomness expansion.Comment: Improved threshold with more data points, discussion of conjecture in
[SGP+21], correction regarding results of [MDR+19
Viral forensic genomics reveals the relatedness of classic herpes simplex virus strains KOS, KOS63, and KOS79
Herpes simplex virus 1 (HSV-1) is a widespread global pathogen, of which the strain KOS is one of the most extensively studied. Previous sequence studies revealed that KOS does not cluster with other strains of North American geographic origin, but instead clustered with Asian strains. We sequenced a historical isolate of the original KOS strain, called KOS63, along with a separately isolated strain attributed to the same source individual, termed KOS79. Genomic analyses revealed that KOS63 closely resembled other recently sequenced isolates of KOS and was of Asian origin, but that KOS79 was a genetically unrelated strain that clustered in genetic distance analyses with HSV-1 strains of North American/European origin. These data suggest that the human source of KOS63 and KOS79 could have been infected with two genetically unrelated strains of disparate geographic origins. A PCR RFLP test was developed for rapid identification of these strains
Corporate Security Responsibility: Towards a Conceptual Framework for a Comparative Research Agenda
The political debate about the role of business in armed conflicts has increasingly raised expectations as to governance contributions by private corporations in the fields of conflict prevention, peace-keeping and postconflict peace-building. This political agenda seems far ahead of the research agenda, in which the negative image of business in conflicts, seen as fuelling, prolonging and taking commercial advantage of violent conflicts,still prevails. So far the scientific community has been reluctant to extend the scope of research on ‘corporate social responsibility’ to the area of security in general and to intra-state armed conflicts in particular. As a consequence, there is no basis from which systematic knowledge can be generated about the conditions and the extent to which private corporations can fulfil the role expected of them in the political discourse. The research on positive contributions of private corporations to security amounts to unconnected in-depth case studies of specific corporations in specific conflict settings. Given this state of research, we develop a framework for a comparative research agenda to address the question: Under which circumstances and to what extent can private corporations be expected to contribute to public security
The global biogeography of tree leaf form and habit
Understanding what controls global leaf type variation in trees is crucial for comprehending their role in terrestrial ecosystems, including carbon, water and nutrient dynamics. Yet our understanding of the factors influencing forest leaf types remains incomplete, leaving us uncertain about the global proportions of needle-leaved, broadleaved, evergreen and deciduous trees. To address these gaps, we conducted a global, ground-sourced assessment of forest leaf-type variation by integrating forest inventory data with comprehensive leaf form (broadleaf vs needle-leaf) and habit (evergreen vs deciduous) records. We found that global variation in leaf habit is primarily driven by isothermality and soil characteristics, while leaf form is predominantly driven by temperature. Given these relationships, we estimate that 38% of global tree individuals are needle-leaved evergreen, 29% are broadleaved evergreen, 27% are broadleaved deciduous and 5% are needle-leaved deciduous. The aboveground biomass distribution among these tree types is approximately 21% (126.4 Gt), 54% (335.7 Gt), 22% (136.2 Gt) and 3% (18.7 Gt), respectively. We further project that, depending on future emissions pathways, 17–34% of forested areas will experience climate conditions by the end of the century that currently support a different forest type, highlighting the intensification of climatic stress on existing forests. By quantifying the distribution of tree leaf types and their corresponding biomass, and identifying regions where climate change will exert greatest pressure on current leaf types, our results can help improve predictions of future terrestrial ecosystem functioning and carbon cycling.EEA Santa CruzFil: Ma, Haozhi. Institute of Integrative Biology. ETH Zurich (Swiss Federal Institute of Technology); SuizaFil: Crowther, Thomas W. Institute of Integrative Biology. ETH Zurich (Swiss Federal Institute of Technology); SuizaFil: Mo, Lidong. Institute of Integrative Biology. ETH Zurich (Swiss Federal Institute of Technology); SuizaFil: Maynard, Daniel S. Institute of Integrative Biology. ETH Zurich (Swiss Federal Institute of Technology); SuizaFil: Maynard, Daniel S. University College London. Department of Genetics, Evolution, and Environment; Reino UnidoFil: Renner, Susanne S. Washington University. Department of Biology; Estados UnidosFil: van den Hoogen, Johan. Institute of Integrative Biology. ETH Zurich (Swiss Federal Institute of Technology); SuizaFil: Zou, Yibiao. Institute of Integrative Biology. ETH Zurich (Swiss Federal Institute of Technology); SuizaFil: Liang, Jingjing. Purdue University. Department of Forestry and Natural Resources; Estados UnidosFil: de-Miguel, Sergio. University of Lleida. Department of Agricultural and Forest Sciences and Engineering; EspañaFil: de-Miguel, Sergio. Joint Research Unit CTFC - AGROTECNIO – CERCA; EspañaFil: Nabuurs, Gert-Jan. Wageningen University and Research; Países BajosFil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina.Fil: Peri, Pablo Luis. Universidad Nacional de la Patagonia Austral.; Argentina.Fil: Peri, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Zohner, Constantin M. Institute of Integrative Biology. ETH Zurich (Swiss Federal Institute of Technology); Suiz
Cooperative Behavior of Kinetically Constrained Lattice Gas Models of Glassy Dynamics
Kinetically constrained lattice models of glasses introduced by Kob and
Andersen (KA) are analyzed. It is proved that only two behaviors are possible
on hypercubic lattices: either ergodicity at all densities or trivial
non-ergodicity, depending on the constraint parameter and the dimensionality.
But in the ergodic cases, the dynamics is shown to be intrinsically cooperative
at high densities giving rise to glassy dynamics as observed in simulations.
The cooperativity is characterized by two length scales whose behavior controls
finite-size effects: these are essential for interpreting simulations. In
contrast to hypercubic lattices, on Bethe lattices KA models undergo a
dynamical (jamming) phase transition at a critical density: this is
characterized by diverging time and length scales and a discontinuous jump in
the long-time limit of the density autocorrelation function. By analyzing
generalized Bethe lattices (with loops) that interpolate between hypercubic
lattices and standard Bethe lattices, the crossover between the dynamical
transition that exists on these lattices and its absence in the hypercubic
lattice limit is explored. Contact with earlier results are made via analysis
of the related Fredrickson-Andersen models, followed by brief discussions of
universality, of other approaches to glass transitions, and of some issues
relevant for experiments.Comment: 59 page
Pairing fluctuations and pseudogaps in the attractive Hubbard model
The two-dimensional attractive Hubbard model is studied in the weak to
intermediate coupling regime by employing a non-perturbative approach. It is
first shown that this approach is in quantitative agreement with Monte Carlo
calculations for both single-particle and two-particle quantities. Both the
density of states and the single-particle spectral weight show a pseudogap at
the Fermi energy below some characteristic temperature T*, also in good
agreement with quantum Monte Carlo calculations. The pseudogap is caused by
critical pairing fluctuations in the low-temperature renormalized classical
regime of the two-dimensional system. With increasing temperature
the spectral weight fills in the pseudogap instead of closing it and the
pseudogap appears earlier in the density of states than in the spectral
function. Small temperature changes around T* can modify the spectral weight
over frequency scales much larger than temperature. Several qualitative results
for the s-wave case should remain true for d-wave superconductors.Comment: 20 pages, 12 figure
Kinetic magnetization by fast electrons in laser-produced plasmas at sub-relativistic intensities
Inclusive jet cross sections and dijet correlations in photoproduction at HERA
Inclusive jet cross sections in photoproduction for events containing a
meson have been measured with the ZEUS detector at HERA using an integrated
luminosity of . The events were required to have a
virtuality of the incoming photon, , of less than 1 GeV, and a
photon-proton centre-of-mass energy in the range . The measurements are compared with next-to-leading-order (NLO) QCD
calculations. Good agreement is found with the NLO calculations over most of
the measured kinematic region. Requiring a second jet in the event allowed a
more detailed comparison with QCD calculations. The measured dijet cross
sections are also compared to Monte Carlo (MC) models which incorporate
leading-order matrix elements followed by parton showers and hadronisation. The
NLO QCD predictions are in general agreement with the data although differences
have been isolated to regions where contributions from higher orders are
expected to be significant. The MC models give a better description than the
NLO predictions of the shape of the measured cross sections.Comment: 43 pages, 12 figures, charm jets ZEU
Dissociation of virtual photons in events with a leading proton at HERA
The ZEUS detector has been used to study dissociation of virtual photons in
events with a leading proton, gamma^* p -> X p, in e^+p collisions at HERA. The
data cover photon virtualities in two ranges, 0.03<Q^2<0.60 GeV^2 and 2<Q^2<100
GeV^2, with M_X>1.5 GeV, where M_X is the mass of the hadronic final state, X.
Events were required to have a leading proton, detected in the ZEUS leading
proton spectrometer, carrying at least 90% of the incoming proton energy. The
cross section is presented as a function of t, the squared four-momentum
transfer at the proton vertex, Phi, the azimuthal angle between the positron
scattering plane and the proton scattering plane, and Q^2. The data are
presented in terms of the diffractive structure function, F_2^D(3). A
next-to-leading-order QCD fit to the higher-Q^2 data set and to previously
published diffractive charm production data is presented
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