pinecone/core-2020-05-10-deduplication huggingface dataset:
A General Framework for the Selection of World Coordinate Systems in Perspective and Catadioptric Imaging Applications

An imaging system with a single effective viewpoint is called a central projection system. The conventional perspective camera is an example of central projection system. A catadioptric realization of omnidirectional vision combines reflective surfaces with lenses. Catadioptric systems with an unique projection center are also examples of central projection systems. Whenever an image is acquired, points in 3D space are mapped into points in the 2D image plane. The image formation process represents a transformation from R3 to R2, and mathematical models can be used to describe it. This paper discusses the definition of world coordinate systems that simplify the modeling of general central projection imaging. We show that an adequate choice of the world coordinate reference system can be highly advantageous. Such a choice does not imply that new information will be available in the images. Instead the geometric transformations will be represented in a common and more compact framework, while simultaneously enabling newer insights. The first part of the paper focuses on static imaging systems that include both perspective cameras and catadioptric systems. A systematic approach to select the world reference frame is presented. In particular we derive coordinate systems that satisfy two differential constraints (the “compactness” and the “decoupling” constraints). These coordinate systems have several advantages for the representation of the transformations between the 3D world and the image plane. The second part of the paper applies the derived mathematical framework to active tracking of moving targets. In applications of visual control of motion the relationship between motion in the scene and image motion must be established. In the case of active tracking of moving targets these relationships become more complex due to camera motion. Suitable world coordinate reference systems are defined for three distinct situations: perspective camera with planar translation motion, perspective camera with pan and tilt rotation motion, and catadioptric imaging system rotating around an axis going through the effective viewpoint and the camera center. Position and velocity equations relating image motion, camera motion and target 3D motion are derived and discussed. Control laws to perform active tracking of moving targets using visual information are established.http://dx.doi.org/10.1023/B:VISI.0000013089.51664.b
Symmetry numbers and chemical reaction rates

Abstract  This article shows how to evaluate rotational symmetry numbers for different molecular configurations and how to apply them to transition state theory. In general, the symmetry number is given by the ratio of the reactant and transition state rotational symmetry numbers. However, special care is advised in the evaluation of symmetry numbers in the following situations: (i) if the reaction is symmetric, (ii) if reactants and/or transition states are chiral, (iii) if the reaction has multiple conformers for reactants and/or transition states and, (iv) if there is an internal rotation of part of the molecular system. All these four situations are treated systematically and analyzed in detail in the present article. We also include a large number of examples to clarify some complicated situations, and in the last section we discuss an example involving an achiral diasteroisomer.http://dx.doi.org/10.1007/s00214-007-0328-
Spectral study and classification of worldwide locations considering several multijunction solar cell technologies

Multi-junction solar cells are widely used in high-concentration photovoltaic systems (HCPV) attaining the highest efficiencies in photovoltaic energy generation. This technology is more dependent on the spectral variations of the impinging Direct Normal Irradiance (DNI) than conventional photovoltaics based on silicon solar cells and consequently demands a deeper knowledge of the solar resource characteristics. This article explores the capabilities of spectral indexes, namely, spectral matching ratios (SMR), to spectrally characterize the annual irradiation reaching a particular location on the Earth and to provide the necessary information for the spectral optimization of a MJ solar cell in that location as a starting point for CPV module spectral tuning. Additionally, the relationship between such indexes and the atmosphere parameters, such as the aerosol optical depth (AOD), precipitable water (PW), and air mass (AM), is discussed using radiative transfer models such as SMARTS to generate the spectrally-resolved DNI. The network of ground-based sun and sky-scanning radiometers AERONET (AErosol RObotic NETwork) is exploited to obtain the atmosphere parameters for a selected bunch of 34 sites worldwide. Finally, the SMR indexes are obtained for every location, and a comparative analysis is carried out for four architectures of triple junction solar cells, covering both lattice match and metamorphic technologies. The differences found among cell technologies are much less significant than among locations
Structural and nuclear characterizations of defects created by noble gas implantation in silicon oxide

Thermally grown silicon oxide layer was implanted at room temperature with 300keV Xe at fluences ranging from 0.5 to 5x10$^16$Xe/cm$^2$. Bubbles created after Xe-implantation provided a low-k silicon oxide that has potential use as a dielectric material for interconnects in Si integrated circuits. Transmission Electron Microscopy (TEM), Rutherford Backscattering Spectrometry (RBS) and Positron Annihilation Spectroscopy (PAS) were used to provide a comprehensive characterization of defects (bubbles, vacancy, gas atoms and other types of defects) created by Xe implantation in $SiO_2$ layer. These measurements suggest that the bubbles observed with TEM for all fluences were a consequence of the interaction between Xe and vacancies (V), with $V_nXe_m$ complexes created in the zone where V and Xe profiles overlap. Negatively charged defects such as ($Si-O^-$, $Si-O-O^-$ and $O_2^-$) are also created after implantation
Intergenerational contacts and depressive symptoms among older parents in Eastern Europe

Objective: We investigate the association between parent-child contact frequency and changes in older parents’ depressive symptoms in Bulgaria, Georgia and Russia. These are countries in which societal transformations may mean that psychological feelings of security engendered by having children in close contact may have particularly important implications for the mental health of older parents. Methods: We analysed data from two waves of the Generation and Gender Surveys conducted three years apart and took account of relationships with more than one child. Analyses were performed using OLS regression models, adjusted for depressive symptoms at baseline. Results: Among mothers increases in depressive symptoms were greater for those who lacked at least weekly contact with any child than for those with frequent contact with at least one child (b = 0.64; p<0.01). Increases in depressive symptoms were associated with infrequent contacts with children, even after controlling for relationship quality (b = 0.55; p<0.05). Among unpartnered fathers, less than weekly meetings with children were associated with increases in depressive symptoms. Conclusions: Among mothers and unpartnered fathers changes in depressive symptoms varied by parent-child contact. The adverse effect of not having a partner on fathers’ mental health was reduced, but not eliminated, by having frequent contacts with adult children
Photoacoustic Measurements of Porphyrin Triplet-State Quantum Yields and Singlet-Oxygen Efficiencies

Photoacoustic calorimetry and luminescence techniques were used to measure singlet oxygen quantum yields (PhiDelta) of selected 5,10,15,20-tetrakis(aryl)porphyrins and of the novel chlorin shown. The use of validated photoacoustic references removes some inconsistencies existing in the literature. Excitation of halogenated porphyrins produces high yields of long-lived triplet states that efficiently transfer their energy to singlet oxygen. A route for red-absorbing, efficient singlet-oxygen photosensitisers is described.http://dx.doi.org/10.1002/(SICI)1521-3765(19981102)4:11<2299::AID-CHEM2299>3.0.CO;2-
Landslides into reservoirs and their impacts on banks

Abstract  Mass wasting processes, like slope failures, on the margins of dam reservoirs, lakes, bays and oceans may generate large water waves that can produce disasters due to flooding over the banks, run up along the shoreline and overtopping dam crests. Therefore, the study of slope failures, the subsequent generation of impulse waves and their consequences are of paramount importance for safety. In this paper the generation and propagation of water waves in reservoirs induced by landslides and their impact on banks were investigated by means of a laboratory study carried out at University of Coimbra wave channel, in a flume measuring 12.0 m  ?  1.5 m  ?  1.0 m (L  ?  H  ?  W), where two banks with variable slope were placed. The study considered the sliding of calcareous blocks over a sliding slope bank into the reservoir, the generation of impulse waves, their propagation in the reservoir and their impact on the downstream bank. A number of waves were generated by different fallings of calcareous blocks, considering different volumes, sliding slopes, initial positions and reservoir depths. All fallings were recorded by video-camera and the results were processed afterwards to obtain the time history of the falling. The water surface variations due to transient waves were measured at five gauges placed between the banks. The waves overtopping and breaking on the downstream bank were also filmed using a video camera, and the hydrodynamic forces on this bank were also measured using four pressure transducers.http://dx.doi.org/10.1007/s10652-007-9039-
Automating HAZOP studies using D-higraphs

In this paper, we present the use of D-higraphs to perform HAZOP studies. D-higraphs is a formalism that includes in a single model the functional as well as the structural (ontological) components of any given system. A tool to perform a semi-automatic guided HAZOP study on a process plant is presented. The diagnostic system uses an expert system to predict the behavior modeled using D-higraphs. This work is applied to the study of an industrial case and its results are compared with other similar approaches proposed in previous studies. The analysis shows that the proposed methodology fits its purpose enabling causal reasoning that explains causes and consequences derived from deviations, it also fills some of the gaps and drawbacks existing in previous reported HAZOP assistant tools
Nanoscale electrical conductivity of the purple membrane monolayer

Nanoscale electron transport through the purple membrane monolayer, a two-dimensional crystal lattice of the transmembrane protein bacteriorhodopsin, is studied by conductive atomic force microscopy. We demonstrate that the purple membrane exhibits nonresonant tunneling transport, with two characteristic tunneling regimes depending on the applied voltage (direct and Fowler-Nordheim). Our results show that the purple membrane can carry significant current density at the nanometer scale, several orders of magnitude larger than previously estimated by macroscale measurements
Twisted compactification of N = 2 5D SCFTs to three and two dimensions from F (4) gauged supergravity

We study supersymmetric AdS 4 × Σ 2 and AdS 3 × Σ 3 solutions in half-maximal gauged supergravity in six dimensions with SU(2) R × SU(2) gauge group. The gauged supergravity is obtained by coupling three vector multiplets to the pure F (4) gauged supergravity. The SU(2) R R-symmetry together with the SO(3) ∼ SU(2) symmetry of the vector multiplets are gauged. The resulting gauged supergravity admits supersymmetric AdS 6 critical points with SO(4) ∼ SU(2) × SU(2) and SO(3) ∼ SU(2) diag symmetries. The former corresponds to five-dimensional N = 2 superconformal field theories (SCFTs) with E 1 ∼ SU(2) symmetry. We find new classes of supersymmetric AdS 4 × Σ 2 and AdS 3 × Σ 3 solutions with Σ 2,3 being S 2,3 and H 2,3 . These solutions describe SCFTs in three and two dimensions obtained from twisted compactifications of the aforementioned five-dimensional SCFTs with different numbers of unbroken supersymmetry and various types of global symmetries
A Study on Residual Compression Behavior of Structural Fiber Reinforced Concrete Exposed to Moderate Temperature Using Digital Image Correlation

Fire ranks high among the potential risks faced by most buildings and structures. A full understanding of temperature effects on fiber reinforced concrete is still lacking. This investigation focuses on the study of the residual compressive strength, stress strain behavior and surface cracking of structural polypropylene fiber-reinforced concrete subjected to temperatures up to 300 A degrees C. A total of 48 cubes was cast with different fiber dosages and tested under compression after exposing to different temperatures. Concrete cubes with varying macro (structural) fiber dosages were exposed to different temperatures and tested to observe the stress-strain behavior. Digital image correlation, an advanced non-contacting method was used for measuring the strain. Trends in the relative residual strengths with respect to different fiber dosages indicate an improvement up to 15 % in the ultimate compressive strengths at all exposure temperatures. The stress-strain curves show an improvement in post peak behavior with increasing fiber dosage at all exposure temperatures considered in this study
Group-wise Construction of Reduced Models for Understanding and Characterization of Pulmonary Blood Flows from Medical Images

International audience3D computational fluid dynamics (CFD) in patient-specific geometries provides complementary insights to clinical imaging, to better understand how heart disease, and the side effects of treating heart disease, affect and are affected by hemodynamics. This information can be useful in treatment planning for designing artificial devices that are subject to stress and pressure from blood flow. Yet, these simulations remain relatively costly within a clinical context. The aim of this work is to reduce the complexity of patient-specific simulations by combining image analysis, computational fluid dynamics and model order reduction techniques. The proposed method makes use of a reference geometry estimated as an average of the population, within an efficient statistical framework based on the currents representation of shapes. Snapshots of blood flow simulations performed in the reference geometry are used to build a POD (Proper Orthogonal Decomposition) basis, which can then be mapped on new patients to perform reduced order blood flow simulations with patient specific boundary conditions. This approach is applied to a data-set of 17 tetralogy of Fallot patients to simulate blood flow through the pulmonary artery under normal (healthy or synthetic valves with almost no backflow) and pathological (leaky or absent valve with backflow) conditions to better understand the impact of regurgitated blood on pressure and velocity at the outflow tracts. The model reduction approach is further tested by performing patient simulations under exercise and varying degrees of pathophysiological conditions based on reduction of reference solutions (rest and medium backflow conditions respectively)
Mg/Ca in fossil oyster shells as palaeotemperature proxy, an example from the Palaeogene of Central Asia

International audienceFossil oyster shells are well-suited to provide palaeotemperature proxies from geologic to seasonal timescales due to their ubiquitous occurrence from Triassic to Quaternary sediments, the seasonal nature of their shell growth and their strong resistance to post-mortem alteration. However, the common use to translate calcitic oxygen isotopes into palaeotemperatures is challenged by uncertainties in accounting for past seawater δ 18 O, especially in shallow coastal environment where oysters calcify. In principle, the Mg/Ca ratio in oyster shells can provide an alternative palaeothermometer. Several studies provided temperature calibrations for this potential proxy based on modern species, nevertheless their application to palaeo-studies remains hitherto unexplored. Here, we show that past temperature variability in seawater can be obtained from Mg/Ca analyses from selected oyster fossil species and specimens. High-resolution Mg/Ca profiles, combined with δ 18 O, were obtained along 41 fossil oyster shells of seven different species from the Palaeogene Proto-Paratethys sea (Central Asia) found in similar as well as different depositional age and environments providing comparison. Suitable Mg/Ca profiles, defined by continuous cyclicity and reproducibility within one shell, are found to be consistent for specimens of the same species but differ systematically between species, implying a dominant species-specific effect on the Mg/Ca incorporation. Two species studied here (Ostrea (Turkostrea) strictiplicata and Sokolowia buhsii) provide an excellent proxy ACCEPTED MANUSCRIPT for palaeoclimate reconstruction from China to Europe in Palaeogene marine sediments. More generally , the protocol developed here can be applied to identify other fossil oyster species suitable for palaeoclimate reconstructions
Yardstick Competition: Which Neighbours Matter?

International audienceThis paper aims at testing the existence of yardstick competition by estimating a fully specified vote-function on a panel data set of 104 French local governments from 1989 to 2001. When comparing the performance of their incumbent to the one of their "neighbours", voters might consider their close geographical neighbours but also the nearby cities that are similar according to some socio-economic characteristics such as population size. The estimation results show that voters sanction their incumbent if their own local housing tax is high. Moreover, we find that voters reward their incumbent when neighbouring cities that are similar in terms of demographic characteristics have high local taxes
Toward full carbon interconnects: High conductivity of individual carbon nanotube to carbon nanotube regrowth junctions

International audienceA versatile chemical vapor deposition (CVD) based method for the fabrication and electrical measurement of individual carbon nanotube junctions was developed. ferritin or Fe particles were grafted on multiwalled carbon nanotubes (MWNTs) and used as catalysts for the subsequent growth of secondary MWNT by CVD. Junctions were then individually connected. The conductivities of the MWNTs and of the junction were measured. Statistical data show that the conductance of the MWNT-MWNT junction is similar to that of MWNT. This result paves the way for the use of carbon nanotubes as electrical interconnects in electronic applications
SHRIMP zircon U–Pb age constraints on Neoproterozoic Quruqtagh diamictites in NW China

International audienceThe Neoproterozoic Quruqtagh Group in the Tarim Block, NW China, contains multiple diamictites in the Bayisi, Altungol, Tereeken, and Hankalchough formations. These diamictites may represent three or possibly four discrete glaciations, although evidence for a glacial origin of the Bayisi and Altungol diamictite is ambiguous. To constrain their age and duration, we dated three volcanic beds (V1, V2, and V3) in the Quruqtagh Group using the SHRIMP (sensitive high-resolution ion microprobe) zircon U–Pb method. Volcanic bed V1 near the base of the Bayisi diamictite yields a 740 ± 7 Ma age, volcanic bed V2 near the top of the Bayisi Formation gives a 725 ± 10 Ma age, and volcanic bed V3 between the Tereeken and Hankalchough diamictites yields a 615 ± 6 Ma age. V1 and V2 have overlapping ages, and together these dates suggest that the Bayisi diamictite was deposited at around 730 Ma. The Tereeken and Altungol diamictites were deposited between 725 ± 10 Ma and 615 ± 6 Ma, and the Hankalchough diamictite between 615 ± 6 Ma and not, vert, similar542 Ma (i.e., the Neoproterozoic–Cambrian transition). These dates and previously published chemostratigraphic data are consistent with (but doe not require) the correlation of the Tereeken and Hankalchough diamictites with the 635 Ma Nantuo and 582 Ma Gaskiers glaciations, respectively. However, the new dates are inconsistent with a single and globally synchronous Sturtian glaciation that occurred in the pre-Nantuo Neoproterozoic Era. Instead, currently available data necessitate that either multiple glaciations occurred, or a globally diachronous glacial event developed during a protracted period between not, vert, similar750 Ma and not, vert, similar650 Ma
Apparent yield stress in rigid fibre suspensions: the role of attractive colloidal interactions

International audienceThis work is focused on the modelling of the shear and normal stresses in fibre suspensions that are subjected to a simple shear flow in the presence of short-range lubrication forces, van der Waals and electrostatic forces, as well as solid friction forces between fibres. All these forces are weighed by the contact probability. The theory is developed for attractive fibres with van der Waals interaction dominating over electrostatic repulsion. The model predicts a simple Bingham law for both the shear stress and the first normal stress difference with the apparent shear and normal yield stresses proportional, respectively, to the second and the third power of particle volume fraction. The model is applied to the experimental data of Rakatekar et al. Adv. Mater 21, 874-878 (2009) and Natale et al. AIChE J. 60, 1476-1487 (2014) on the suspensions of carbon nanotubes dispersed in a Newtonian epoxy resin. It reproduces well the quadratic dependency of the apparent yield stress on particle volume fraction (σ Y ∝φ^2)  for average particle aspect ratios of r=160 and 1200, while it underpredicts the power-law exponent for rD80 (always predictingφ^2 behaviour instead of φ^3.2
Use of ram extruder as a combined rheo-tribometer to study the behaviour of high yield stress fluids at low strain rate

International audienceWe propose in this work to provide an efficient and simple extruder device able to evaluate the rheological and tribological behaviour of high yield stress fluids, such as extrudible materials. An extruder able to measure simultaneously both the friction force acting on the extruder wall and the total extrusion force is developed. Based on previous studies, an efficient and accurate method of data analysis is then proposed and applied in order to obtain both a flow curve and a tribological law. Experimental tests are performed on soft modelling clay, kaolin paste and cement-based materials. Results are compared to conventional rheometry measurements. This comparison helps to evaluate the accuracy of the proposed experimental device and procedure