4,311 research outputs found
Summary of pre-2008 Machine Induced Background Estimates for the LHCb Experiment
This document summarizes the pre-2008 estimates of particle flux arriving at the LHCb experiment from machine (LHC) related background sources. These particles arrive in the form of showers from both beam-gas interactions in the dispersion suppression and long straight section of IR8 and from proton losses on the IR8 tertiary collimators due to betatron cleaning inefficiencies, momentum cleaning inefficiencies and elastic beam-gas interactions along the LHC beam orbit
Amine-Rich Carbon Dots as Novel Nano-Aminocatalytic Platforms in Organic Synthesis
The development of novel and effective metal-free catalytic systems, which can drive value-added organic transformations in environmentally benign solvents (for instance, water), is highly desirable. Moreover, these new catalysts need to be harmless, easy-to-prepare, and potentially recyclable. In this context, amine-rich carbon dots (CDs) have recently emerged as promising nano-catalytic platforms. These nitrogen-doped nanoparticles, which show dimensions smaller than 10 nm, generally consist of carbon cores that are surrounded by shells containing numerous amino groups. In recent years, organic chemists have used these surface amines to guide the design of several synthetic methodologies under mild operative conditions. This Concept highlights the recent advances in the synthesis of amine-rich carbon dots and their applications in organic catalysis, including forward-looking opportunities within this research field
APPLICATION OF LUCAS-KANADE DENSE FLOW FOR TERRAIN MOTION IN LANDSLIDE MONITORING APPLICATION
Landslides are natural hazards that can cause severe damage and loss of life. Optical cameras are a low-cost and high-resolution
alternative among many monitoring systems, as their size and capabilities can vary, allowing for flexible implementation and location.
Computer vision is a branch of artificial intelligence that can analyze and understand optical images, using techniques such as
optical flow, image correlation and machine learning. The application of such techniques can estimate the motion vectors, displacement
fields, providing valuable information for landslide detection, monitoring and prediction. However, computer vision also faces
some challenges such as illumination changes, occlusions, image quality, and computational complexity. In this work, a computer
vision approach based on Lucas-Kanade optical dense flow was applied to estimate the motion vectors between consecutive images
obtained during landslide simulations in a laboratory environment. The approach is applied to two experiments that vary in their
illumination and setup parameters to test its applicability. We also discuss the application of this methodology to images from
Sentinel-2 satellite optical sensors for landslide monitoring in real-world scenarios
Manual erythroexchange in sickle cell disease: multicenter validation of a protocol predictive of volume to exchange and hemoglobin values
Manual erythroexchange (MEEX) was proven to be effective and safe in the management of sickle cell disease (SCD). The goal is to quickly reduce the percentage of hemoglobin S (HbS%). A national survey of the Italian Society for Thalassemia and Hemoglobinopathies (SITE) observed a great variability among MEEX protocols none of which were found to be predictive of the values of HbS% and hemoglobin (Hb) after the exchange. Two equations to estimate the HbS% and Hb values to be obtained after MEEX were developed based on the results of the MEEX procedures in place in the centers participating in the present study. A standard protocol was subsequently defined to evaluate the volumes to exchange to obtain the target values of HbS% and Hb. The protocol was tested in 261 MEEX performed in SCD patients followed in the 5 participating centers that belong to the Italian Hemoglobinopathy Comprehensive Care Network, with the support of the SITE. The results showed a correlation between the estimated and measured values of HbS% and Hb (Rp 0.95 and 0.65 respectively, p < 0.001). A negligible bias was found for the prediction of HbS% and a bias of 1 g/dl for Hb. From consecutive MEEX, a rate of increase of HbS% between two exchanges of around 0.4% per day (p < 0.001) was measured. This protocol was shown to be effective and safe, as all patients reached the target value of HbS%. All the MEEX procedures were carried out with single venous access. No adverse events or reactions such as hypotension or electrolyte imbalance were reported nor were any complaints concerning the procedures received from patients
Disorder and Impurities in Hubbard-Antiferromagnets
We study the influence of disorder and randomly distributed impurities on the
properties of correlated antiferromagnets. To this end the Hubbard model with
(i) random potentials, (ii) random hopping elements, and (iii) randomly
distributed values of interaction is treated using quantum Monte Carlo and
dynamical mean-field theory. In cases (i) and (iii) weak disorder can lead to
an enhancement of antiferromagnetic (AF) order: in case (i) by a
disorder-induced delocalization, in case (iii) by binding of free carriers at
the impurities. For strong disorder or large impurity concentration
antiferromagnetism is eventually destroyed. Random hopping leaves the local
moment stable but AF order is suppressed by local singlet formation. Random
potentials induce impurity states within the charge gap until it eventually
closes. Impurities with weak interaction values shift the Hubbard gap to a
density off half-filling. In both cases an antiferromagnetic phase without
charge gap is observed.Comment: 16 pages, 9 figures, latex using vieweg.sty (enclosed); typos
corrected, references updated; to appear in "Advances in Solid State
Physics", Vol. 3
Del Pezzo surfaces with 1/3(1,1) points
We classify del Pezzo surfaces with 1/3(1,1) points in 29 qG-deformation
families grouped into six unprojection cascades (this overlaps with work of
Fujita and Yasutake), we tabulate their biregular invariants, we give good
model constructions for surfaces in all families as degeneracy loci in rep
quotient varieties and we prove that precisely 26 families admit
qG-degenerations to toric surfaces. This work is part of a program to study
mirror symmetry for orbifold del Pezzo surfaces.Comment: 42 pages. v2: model construction added of last remaining surface,
minor corrections, minor changes to presentation, references adde
Nonmonotonical crossover of the effective susceptibility exponent
We have numerically determined the behavior of the magnetic susceptibility
upon approach of the critical point in two-dimensional spin systems with an
interaction range that was varied over nearly two orders of magnitude. The full
crossover from classical to Ising-like critical behavior, spanning several
decades in the reduced temperature, could be observed. Our results convincingly
show that the effective susceptibility exponent gamma_eff changes
nonmonotonically from its classical to its Ising value when approaching the
critical point in the ordered phase. In the disordered phase the behavior is
monotonic. Furthermore the hypothesis that the crossover function is universal
is supported.Comment: 4 pages RevTeX 3.0/3.1, 5 Encapsulated PostScript figures. Uses
epsf.sty. Accepted for publication in Physical Review Letters. Also available
as PostScript and PDF file at http://www.tn.tudelft.nl/tn/erikpubs.htm
Birational rigidity of a three-dimensional double cone
It is proved that a three-dimensional double cone is a birationally rigid
variety. We also compute the group of birational automorphisms of such a
variety. This work is based on the method of "untwisting" maximal singularities
of linear system.Comment: 20 pages; AmsLaTe
Evolutionary history of Podarcis tiliguerta on Corsica and Sardinia.
BACKGROUND: Podarcis tiliguerta is a wall lizard endemic to the Mediterranean islands of Corsica and Sardinia. Previous findings of high mtDNA and morphological diversity have led to the suggestion that it may represent a species complex. Here, we analysed mitochondrial and nuclear markers (mtDNA, 3110Â bp; 6 nDNA loci, 3961Â bp) in P. tiliguerta sampled from thirty-two localities across Corsica and Sardinia. RESULTS: We find much greater intraspecific genetic divergence than between sister species of other Mediterranean island Podarcis, i.e., between P. lilfordi and P. pityusensis. We detected three mtDNA clusters in Corsica (North, South-East and South-West) and either two or three in Sardinia (North vs. South) depending on the clustering method. Only one or two nDNA groups were identified within each main island (again, depending on the method). A Bayesian time-calibrated multispecies coalescent tree was obtained from mtDNA and provided statistical support for a Miocene origin of the species (13.87Â Ma, 95% HPD: 18.30-10.77Â Ma). The posterior mean divergence time for the Corsican and Sardinian lineages was 12.75Â Ma ago (95% HPD: 16.94-9.04Â Ma). CONCLUSION: The results support the evolutionary distinctiveness of Corsican and Sardinian populations and also indicate a lack of post-divergence migration despite periods of contact being possible. Further to this, species delimitation analyses of Corsican and Sardinian lineages provided statistical support for their recognition as distinct (sister) taxa. Our results provide new insights into the biogeography of the Mediterranean biodiversity hotspot, and contribute important findings relevant to the systematics and evolution of this speciose lizard genus
Distinguishing G_2-manifolds
In this survey, we describe invariants that can be used to distinguish
connected components of the moduli space of holonomy G_2 metrics on a closed
7-manifold, or to distinguish G_2-manifolds that are homeomorphic but not
diffeomorphic. We also describe the twisted connected sum and extra-twisted
connected sum constructions used to realise G_2-manifolds for which the above
invariants differ.Comment: 22 pages, 5 figures. To appear in a forthcoming volume of the Fields
Institute Communications, entitled "Lectures and Surveys on G2 manifolds and
related topics
- …