pinecone/core-2020-05-10-deduplication huggingface dataset:
Optimizing replacement policy for a cold-standby system with waiting repair times

This paper presents the formulas of the expected long-run cost per unit time for a cold-standby system composed of two identical components with perfect switching. When a component fails, a repairman will be called in to bring the component back to a certain working state. The time to repair is composed of two different time periods: waiting time and real repair time. The waiting time starts from the failure of a component to the start of repair, and the real repair time is the time between the start to repair and the completion of the repair. We also assume that the time to repair can either include only real repair time with a probability p, or include both waiting and real repair times with a probability 1 − p. Special cases are discussed when both working times and real repair times are assumed to be geometric processes, and the waiting time is assumed to be a renewal process. The expected long-run cost per unit time is derived and a numerical example is given to demonstrate the usefulness of the derived expression
Recent advances in the structural and molecular biology of type IV secretion systems

Bacteria use type IV secretion (T4S) systems to deliver DNA and protein substrates to a diverse range of prokaryotic and eukaryotic target cells. T4S systems have great impact on human health, as they are a major source of antibiotic resistance spread among bacteria and are central to infection processes of many pathogens. Therefore, deciphering the structure and underlying translocation mechanism of T4S systems is crucial to facilitate development of new drugs. The last five years have witnessed considerable progress in unraveling the structure of T4S system subassemblies, notably that of the T4S system core complex, a large 1 MegaDalton (MDa) structure embedded in the double membrane of Gram-negative bacteria and made of 3 of the 12 T4S system components. However, the recent determination of the structure of ∼3 MDa assembly of 8 of these components has revolutionized our views of T4S system architecture and opened up new avenues of research, which are discussed in this review
3D analysis from micro-MRI during in situ compression on cancellous bone.

The authors would like to acknowledge Claude Verliac and Joachim Magnier for technical advice on the manufacturing process of the mechanical loading system.A mini-compression jig was built to perform in situ tests on bovine trabecular bone monitored by micro-MRI. The MRI antenna provided an isotropic resolution of 78 microm that allows for a volume correlation method to be used. Three-dimensional displacement fields are then evaluated within the bone sample during the compression test. The performances of the correlation method are evaluated and discussed to validate the technique on trabecular bone. By considering correlation residuals and estimates of acquisition noise, the measured results are shown to be trustworthy. By analyzing average strain levels for different interrogation volumes along the loading direction, it is shown that the sample size is less than that of a representative volume element. This study shows the feasibility of the 3D-displacement and strain field analyses from micro-MRI images. Other biological tissues could be considered in future work
Mars environment and magnetic orbiter model payload

Abstract  Mars Environment and Magnetic Orbiter was proposed as an answer to the Cosmic Vision Call of Opportunity as a M-class mission. The MEMO mission is designed to study the strong interconnections between the planetary interior, atmosphere and solar conditions essential to understand planetary evolution, the appearance of life and its sustainability. MEMO provides a high-resolution, complete, mapping of the magnetic field (below an altitude of about 250 km), with an yet unachieved full global coverage. This is combined with an in situ characterization of the high atmosphere and remote sensing of the middle and lower atmospheres, with an unmatched accuracy. These measurements are completed by an improved detection of the gravity field signatures associated with carbon dioxide cycle and to the tidal deformation. In addition the solar wind, solar EUV/UV and energetic particle fluxes are simultaneously and continuously monitored. The challenging scientific objectives of the MEMO mission proposal are fulfilled with the appropriate scientific instruments and orbit strategy. MEMO is composed of a main platform, placed on a elliptical (130 × 1,000 km), non polar (77° inclination) orbit, and of an independent, higher apoapsis (10,000 km) and low periapsis (300 km) micro-satellite. These orbital parameters are designed so that the scientific return of MEMO is maximized, in terms of measurement altitude, local time, season and geographical coverage. MEMO carry several suites of instruments, made of an ‘exospheric-upper atmosphere’ package, a ‘magnetic field’ package, and a ‘low-middle atmosphere’ package. Nominal mission duration is one Martian year.http://dx.doi.org/10.1007/s10686-008-9101-
Characterization of cobalt- and copper hexacyanoferrate-modified carbon film electrodes for redox-mediated biosensors

Cobalt and copper hexacyanoferrate films (CoHCF and CuHCF) were formed at carbon film electrodes by three different one-step processes: cycling the applied potential, application of a constant current, and chemically. All hexacyanoferrate films obtained were characterized electrochemically by cyclic voltammetry and electrochemical impedance spectroscopy. To evaluate their possible use as redox mediators for biosensors, they were applied to the determination of hydrogen peroxide in neutral phosphate buffer saline electrolyte. Chemically deposited CuHCF was found to be generally the most suitable as a mediator, although CoHCF made by potential cycling is the most useful when a very low detection limit is necessary.http://dx.doi.org/10.1007/s10008-004-0632-
FTIR spectroscopy structural analysis of the interaction between Lactobacillus kefir S-layers and metal ions

FTIR spectroscopy was used to structurally characterize the interaction of S-layer proteins extracted from two strains of Lactobacillus kefir (the aggregating CIDCA 8348 and the non-aggregating JCM 5818) with metal ions (Cd+2, Zn+2, Pb+2 and Ni+2). The infrared spectra indicate that the metal/protein interaction occurs mainly through the carboxylate groups of the side chains of Asp and Glut residues, with some contribution of the NH groups belonging to the peptide backbone. The frequency separation between the νCOO− anti-symmetric and symmetric stretching vibrations in the spectra of the S-layers in presence of the metal ions was found to be ca. 190 cm−1 for S-layer CIDCA 8348 and ca. 170 cm−1 for JCM 5818, denoting an unidentate coordination in both cases. Changes in the secondary structures of the S-layers induced by the interaction with the metal ions were also noticed: a general trend to increase the amount of β-sheet structures and to reduce the amount of α-helices was observed. These changes allow the proteins to adjust their structure to the presence of the metal ions at minimum energy expense, and accordingly, these adjustments were found to be more important for the bigger ions
On Leggett Theories: A Reply

In his 2013 Foundations of Physics paper Mathias Egg claims to show that my critical arguments toward the foundational significance of Leggett’s non-local theories are misguided. The main motivation is that my argument would connect too strongly the Leggett original motivation for introducing this new class of theories with the foundational significance of these theories per se. Egg basically aims to show that, although it can be conceded that the Leggett original motivation relies on a mistaken view of the original Bell theorem, the investigation on the Leggett theories does have a foundational meaning that can be disassociated from the view that Leggett himself has of of them. As a reply to Egg, I would like to argue here that, even if we assume to disentangle the Leggett view from the fate of the Leggett theories, there is still room to dispute the foundational significance of the Leggett ‘non-local realistic’ research program
Impact of carrier localization on the photoluminescence characteristics of (Ga,In)(N,As) and (Ga,In)(N,As,Sb) quantum wells

Using photoluminescence (PL) spectroscopy, we carry out a comparative study of the optical properties of (Ga,In)(N,As) and (Ga,In)(N,As,Sb) quantum wells. The incorporation of Sb into (Ga,In)(N,As) results in a reduced quantum efficiency at low temperatures but an improved one at room temperature (RT). A PL line shape analysis as well as the temperature dependence of the PL peak energy reveals the existence of band-tail localized states in both material systems. The carrier localization energy is larger for (Ga,In)(N,As,Sb) than for (Ga,In)(N,As), leading to a longer radiative lifetime and thus a reduced quantum efficiency at low temperatures for the former material. The thermal quenching of the quantum efficiency is analyzed by a rate equation model, which shows that the density of nonradiative centers is reduced in (Ga,In)(N,As,Sb) resulting in an enhanced quantum efficiency at RT
Airport Taxi Planning: Lagrangian Decomposition

The airport taxi planning (TP) module is a decision tool intended to guide airport surface management\ud
operations. TP is defined by a flow network optimization model that represents flight ground movements and\ud
improves aircraft taxiing routes and schedules during periods of aircraft congestion. TP is not intended to\ud
operate as a stand‐alone tool for airport operations management: on the contrary, it must be used in\ud
conjunction with existing departing and arriving traffic tools and overseen by the taxi planner of the airport,\ud
also known as the aircraft ground controller. TP must be flexible in order to accommodate changing inputs\ud
while maintaining consistent routes and schedules already delivered from past executions. Within this\ud
dynamic environment, the execution time of TP may not exceed a few minutes. Classic methods for solving\ud
binary multi‐commodity flow networks with side constraints are not efficient enough; therefore, a Lagrangian\ud
decomposition methodology has been adapted to solve it. We demonstrate TP Lagrangian decomposition\ud
using actual data from the Madrid‐Barajas Airpor
Symmetry considerations in the empirical k.p Hamiltonian for the study of intermediate band solar cells

With the purpose of assessing the absorption coefficients of quantum dot solar cells, symmetry considerations are introduced into a Hamiltonian whose eigenvalues are empirical. In this way, the proper transformation from the Hamiltonian's diagonalized form to the form that relates it with  Γ-point exact solutions through k.p envelope functions is built accounting for symmetry. Forbidden transitions are thus determined reducing the calculation burden and permitting a thoughtful discussion of the possible options for this transformation. The agreement of this model with the measured external quantum efficiency of a prototype solar cell is found to be excellent
Analysis of Juniperus communis subsp. alpina needle, berry, wood and root oils by combination of GC, GC/MS and 13C-NMR

The essential oils from needles, berries, wood and roots of Juniperus communis L. subsp. alpina were obtained by hydrodistillation, fractionated on column chromatography and analysed by GC, GC-MS and 13C-NMR. Chemical compositions of wood and root oils are reported here for the first time. Eighty-two, 65, 76 and 54 components were identified, respectively, in needle, berry, wood and root oils. The chemical compositions of the essential oils from needles, berries and wood were characterized by a high proportion of monoterpene hydrocarbons. Root oil exhibited a quite different composition. Sesquiterpenes, especially those bearing a tricyclic skeleton (cedrane and longifolane), constituted the main fraction while monoterpenes were present at very low contents. Copyright © 2005 John Wiley & Sons, Ltd.http://dx.doi.org/10.1002/ffj.152
Selective oviposition of the mayfly Baetis bicaudatus

Abstract  Selective oviposition can have important consequences for recruitment limitation and population dynamics of organisms with complex life cycles. Temporal and spatial variation in oviposition may be driven by environmental or behavioral constraints. The goals of this study were to: (1) develop an empirical model of the substrate characteristics that best explain observed patterns of oviposition by Baetis bicaudatus (Ephemeroptera), whose females lay eggs under rocks protruding from high-elevation streams in western Colorado; and (2) test experimentally selective oviposition of mayfly females. We surveyed the number and physical characteristics of potential oviposition sites, and counted the number and density of egg masses in different streams of one watershed throughout two consecutive flight seasons. Results of surveys showed that variability in the proportion of protruding rocks with egg masses and the density of egg masses per rock were explained primarily by seasonal and annual variation in hydrology, and variation in geomorphology among streams. Moreover, surveys and experiments showed that females preferred to oviposit under relatively large rocks located in places with high splash associated with fast current, which may provide visual, mechanical or both cues to females. Experiments also showed that high densities of egg masses under certain rocks were caused by rock characteristics rather than behavioral aggregation of ovipositing females. While aggregations of egg masses provided no survival advantage, rocks selected by females had lower probabilities of desiccating during egg incubation. Our data suggest that even when protruding rocks are abundant, not all rocks are used as oviposition sites by females, due to female selectivity and to differences in rock availability within seasons, years, or streams depending on variation in climate and hydrogeomorphology. Therefore, specialized oviposition behavior combined with variation in availability of quality oviposition substrata has the potential to limit recruitment of this species.http://dx.doi.org/10.1007/s00442-006-0376-
Developing mathematical thinking in the primary classroom: liberating students and teachers as learners of mathematics

This paper reports on a research study conducted with a group of practising primary school teachers (n = 24) in North East Scotland during 2011–2012. The teachers were all participants in a newly developed Masters course that had been designed with the aim of promoting the development of mathematical thinking in the primary classroom as part of project supported by the Scottish Government. The paper presents the background for this initiative within the context of the Scottish Curriculum for Excellence reform. Particular attention is given to the epistemological positioning of the researchers as this influenced both the curriculum design process and also the theoretical framing of the research study which are both described. The project was set up within a design research framework, which aimed to promote classroom-based action research on the part of participants through the course and also research by the university researchers into the process of curriculum development. The research questions focused on the teachers’ confidence, competence, attitudes and beliefs in relation to mathematics and their expectations and experiences of the impact on pupil learning arising from this course. Empirical data were drawn from pre- and post-course surveys, interviews and observations of the discussion forums in the online environment. Findings from this study highlight the way the course had a transformational and emancipatory impact on these teachers. They also highlight ways in which the ‘framing’ of particular aspects of the curriculum had an oppressive impact on learners in the ways that suppressed creativity and limited the exercise of learner autonomy. Furthermore, they highlight the ways in which a number of these teachers had experienced mathematics as a school subject in very negative ways, involving high levels of ‘symbolic violence’ and of being ‘labelled’
On Semi-implicit Splitting Schemes for the Beltrami Color Image Filtering

The Beltrami flow is an efficient nonlinear filter, that was shown to be effective for color image processing. The corresponding anisotropic diffusion operator strongly couples the spectral components. Usually, this flow is implemented by explicit schemes, that are stable only for very small time steps and therefore require many iterations. In this paper we introduce a semi-implicit Crank-Nicolson scheme based on locally one-dimensional (LOD)/additive operator splitting (AOS) for implementing the anisotropic Beltrami operator. The mixed spatial derivatives are treated explicitly, while the non-mixed derivatives are approximated in an implicit manner. In case of constant coefficients, the LOD splitting scheme is proven to be unconditionally stable. Numerical experiments indicate that the proposed scheme is also stable in more general settings. Stability, accuracy, and efficiency of the splitting schemes are tested in applications such as the Beltrami-based scale-space, Beltrami denoising and Beltrami deblurring. In order to further accelerate the convergence of the numerical scheme, the reduced rank extrapolation (RRE) vector extrapolation technique is employed
Some Puzzles and Unresolved Issues About Quantum\ud
Entanglement

Schrödinger (1935) averred that entanglement is the characteristic trait of quantum mechanics. The first part of this paper is simultaneously an exploration of Schrödinger's claim and an investigation into the distinction between mere entanglement and genuine quantum entanglement. The typical discussion of these matters in the philosophical literature neglects the structure of the algebra of observables, implicitly assuming a tensor product structure of the simple Type I factor algebras used in ordinary QM. This limitation is overcome by adopting the algebraic approach to quantum physics, which allows a uniform treatment of ordinary QM, relativistic QFT, and quantum statistical mechanics. The algebraic apparatus helps to distinguish several different criteria of quantum entanglement and to prove results about the relation of quantum entanglement to two additional ways of characterizing the classical vs. quantum divide, viz. abelian vs. non-abelian algebras of observables, and the ability vs. inability to interrogate the system without disturbing it. Schrödinger's claim is reassessed in the light of this discussion. The second part of the paper deals with the relativity-to-ambiguity threat: the entanglement of a state on a system algebra is entanglement of the state relative to a decomposition of the system algebra into subsystem algebras; a state may be entangled with respect to one decomposition but not another; hence, unless there is some principled way to choose a decomposition, entanglement is a radically ambiguous notion. The problem is illustrated in terms a Realist vs. Pragmatist debate, the former claiming that the decomposition must correspond to real as opposed to virtual subsystems, while the latter claims that the real vs. virtual distinction is bogus and that practical considerations can steer the choice of decomposition. This debate is applied to the fraught problem of measuring entanglement for indistinguishable particles. The paper ends with some (intentionally inflammatory) remarks about claims in the philosophical literature that entanglement undermines the separability or independence of subsystems while promoting holism.\ud
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State mixing and the cubic crystal field approximation for rare earth ions: the case of the Er3+ ion in axial crystal fields

The validity of the cubic crystal field (CCF) approximation for the interpretation of the magnetic resonance properties of the Er3+ ion in crystal fields with tetragonal and trigonal symmetry is examined. The ground state paramagnetic resonance principal g values are explicitly calculated in terms of the cubic crystal field eigenstates as a function of axial crystal field strength. It is shown that, depending on the ground state crystal field eigenstate, the widely accepted CCF approximation of simply taking the average of the trace of the g tensor and equating it to the g value found in cubic symmetry can lead to a misinterpretation of the ground state Stark level and the lattice coordination of the ion. The implications for experimentally reported results are discussed
Investigating the respective impacts of groundwater exploitation and climate change on wetland extension over 150 years

International audiencePeatlands are complex ecosystems driven by many physical, chemical, and biological processes. Peat soils have a significant impact on water quality, ecosystem productivity and greenhouse gas emissions. However, the extent of peatlands is decreasing across the world, mainly because of anthropogenic activities such as drainage for agriculture or groundwater abstractions in underlying aquifers. Potential changes in precipitation and temperature in the future are likely to apply additional pressure to wetland. In this context, a methodology for assessing and comparing the respective impacts of groundwater abstraction and climate change on a groundwater-fed wetland (135 km2) located in Northwest France, is presented. A groundwater model was developed, using flexible boundary conditions to represent surface-subsurface interactions which allowed examination of the extent of the wetland areas. This variable parameter is highly important for land management and is usually not considered in impact studies. The model was coupled with recharge estimation, groundwater abstraction scenarios, and climate change scenarios downscaled from 14 GCMs corresponding to the A1B greenhouse gas (GHG) scenario over the periods 1961-2000 and 2081-2100. Results show that climate change is expected to have an important impact and reduce the surface of wetlands by 5.3-13.6%. In comparison, the impact of groundwater abstraction (100% increase in the expected scenarios) would lead to a maximum decrease of 3.7%. Results also show that the impacts of climate change and groundwater abstraction could be partially mitigated by decreasing or stopping land drainage in specific parts of the area. Water management will require an appropriate compromise which encompasses ecosystem preservation, economic and public domain activities