Miracle-dz/UniFAR-FTUs huggingface dataset:
Modelling Variability in the Branching Structure of Strawberry Inflorescences

The branching structure of inflorescences of the cultivated strawberry (Fragaria×ananassa Duch.) is very variable. This paper demonstrates that some aspects of this variability are well described by a simple stochastic model of branching that has two adjustable parameters. The model is shown to provide a good fit to data from a set of almost 700 inflorescences of the cultivar Elsanta, collected over two successive years. For one parameter the maximum likelihood estimator is a moment estimator which is fully efficient even if the detailed branching structure of the inflorescences is not recorded. This parameter provides a convenient summary of branching vigour. The maximum likelihood estimator of the second parameter must be determined iteratively and can be quite inefficient unless the full branching structure is recorded. The model demonstrates that branching structure is affected by the order in which inflorescences emerge on the plant.
Assessing the risk of airborne spread of foot‐and‐mouth disease: A case study

Foot-and-mouth disease (FMD) is a highly infectious viral disease of cloven-hoofed animals, both domestic and wild. In 2001 it had a dramatic effect on the UK farming community and tourism, when the country experienced one of its worst epidemics (Royal Society 2002). Gloster et al. (2004a, b) described the disease, how it spreads and reviewed the part that meteorology played in the epidemic. This paper extends the work recorded in these papers by considering in detail a specific case study and investigates the hypothesis that the airborne virus could have been responsible for the introduction of FMD virus to the south-west of Scotland from the Cumbria area. It also seeks to establish a formal method by which an assessment of risk from airborne introduction can be made in the future. The Department for Environment, Food and Rural Affairs (Defra) is responsible for the control and eradication of incursions of FMD. For this task the mechanisms for disease spread must be clearly understood and the specific circumstances at the time of the incursion established. During the 2001 UK epidemic, Defra field staff investigated in detail the origin and spread of all cases of FMD. In many instances several routes by which virus could have entered a farm were identified. However, in a number of outbreaks it was difficult or impossible to establish the route of entry. Post epidemic studies have helped clarify the situation but still there are some outbreaks for which the route of infection is uncertain. For example, Thrusfield et al. (2005) carried out a study of the characteristics of the 177 outbreaks in Dumfries and Galloway, in which they ascribed probable and possible sources for outbreaks in the various clusters. In some clusters they were unable to identify sources including outbreaks in areas north of the Solway Firth, Kirkconnell (Defra designated cluster – Dumfries South), Rockcliffe (Defra designated cluster – Dalbeattie South), Kirkbean and Whithorn/Sorbie. The location of these towns/clusters is given in Fig. 1 and a detailed map of the widespread outbreaks in the Cumbria and Dumfries and Galloway areas may be found on the Defra website at http://footandmouth.csl. gov.uk/ secure/images/northcumbria.jpg.
Optimal Sobolev imbeddings

Abstract The aim of this paper is to study Sobolev-type imbedding inequalities involving rearrangement-invariant Banach function norms. We establish the equivalence of a Sobolev imbedding to the boundedness of a certain weighted Hardy operator. This Hardy operator is then used to prove the existence of rearrangement-invariant norms that are optimal in the imbedding inequality. Our approach is to use the methods and principles of Interpolation Theory.
Future gravitational physics tests from ranging to the BepiColombo Mercury planetary orbiter

Milani et al. recently have published careful and fundamental studies of the accuracy with which both gravitational physics information and the solar quadrupole moment can be obtained from Earth-Mercury distance data. To complement these results, a quite different analysis method is used in the present paper. We calculate the first-order corrections to the Keplerian motion of a single planet around the Sun due to the parameterized post-Newtonian theory parameters {beta}, {gamma}, {alpha}{sub 1}, {alpha}{sub 2}, and {xi}, as well as corrections due to the solar quadrupole moment J{sub 2} and a possible secular change in GM{sub {center_dot}}. The Nordtvedt parameter {eta} that is used in tests of the strong equivalence principle also is included in this analysis. The expected accuracies are given for 1 yr, 2 yr, and 8 yr mission durations, assuming that the planet-planet and asteroid-planet perturbations are accurately known. The ''modified worst-case'' error analysis method that we use is quite different from the usual covariance analysis method based on assumed uncorrelated random errors, plus a bias that is fixed or that changes in a prescribed way. We believe this is appropriate because systematic measurement errors are likely to be the main limitation on the accuracy of themore » results. Our final estimated uncertainties are one-third of the errors that would result if a 4.5-cm rms systematic error had the most damaging possible variation with time. We discuss the resulting uncertainties for several different subsets of orbital and relativity parameters. « less
Accommodating stochastic departures from percentile invariance in causal models

Summary. Consider a clinical trial in which participants are randomized to a single‐dose treatment or a placebo control and assume that the adherence level is accurately recorded. If the treatment is effective, then good adherers in the treatment group should do better than poor ad‐ herers because they received more drug; the treatment group data follow a dose–response curve. But, good adherers to the placebo often do better than poor adherers, so the observed adherence–response in the treatment group cannot be completely attributed to the treatment. Efron and Feldman proposed an adjustment to the observed adherence–response in the treatment group by using the adherence–response in the control group. It relies on a percentile invariance assumption under which each participant's adherence percentile within their assigned treatment group does not depend on the assigned group (active drug or placebo). The Efron and Feldman approach is valid under percentile invariance, but not necessarily under departures from it. We propose an analysis based on a generalization of percentile invariance that allows adherence percentiles to be stochastically permuted across treatment groups, using a broad class of stochastic permutation models. We show that approximate maximum likelihood estimates of the underlying dose–response curve perform well when the stochastic permutation process is correctly specified and are quite robust to model misspecification.
Effect of electron blocking layer on efficiency droop in InGaN/GaN multiple quantum well light-emitting diodes

The effect of an electron blocking layer (EBL) on the efficiency droop in InGaN/GaN multiple quantum well light-emitting diodes (LEDs) is investigated. At low current density, the LEDs with a p-AlGaN EBL show a higher external quantum efficiency (EQE) than LEDs without an EBL. However, the EQE of LEDs without an EBL is higher than LEDs with an EBL as injection current density is increased. The improved EQE of LEDs without an EBL at high current density is attributed to the increased hole injection efficiency.
Non-Nested Tests for Competing Models Estimated by Generalized Method of Moments

Non-nested tests are proposed for competing models estimated by generalized method of moments. Results are presented for non-nested linear regression models with het- eroskedasticity and serial correlation of unknown form and differing instrument validity assumptions. Regression forms of the statistics are also presented. THIS PAPER IS CONCERNED with providing a procedure whereby non-nested models estimated by generalized method of moments (GMM) (Hansen (1982)) may be com- pared. In particular, Cox-type (Cox (1961, 1962)) and encompassing tests (Mizon and Richard (1986)) are proposed. Implicit in such tests is a degree of arbitrariness in the way the statistics are constructed as, typically, the assumptions underlying GMM estima- tion techniques are minimal and do not fully specify the data generation process (DGP) underlying the observable random variables, in contradistinction to the method of maximum likelihood. Our procedures allow the population moment conditions on which GMM estimation of the competing models is based to differ in the conditioning sets under which conditional expectation is taken; such differences may reflect different a priori assumptions concerning the exogeneity status of random variables in the models. These tests may be regarded as generalizations of Singleton (1985). More recent work includes Ghysels and Hall (1990) which requires the specification of the DGP under the null hypothesis and Wooldridge (1990b) which proposes heteroskedasticity-robust tests for non-nested non-linear regression models. Our results are specialized to provide non-nested tests for competing regression models estimated by instrumental variables, where we allow a degree of heteroskedastic- ity and serial correlation in the process generating the disturbance terms, by assuming appropriate mixing conditions (White (1984)), and the instrument validity assumptions to differ across the models; cf. Godfrey (1983, 1984) which assume a scalar covariance matrix for the disturbances and that the set of instruments is valid in both models. Thus, our framework includes models which may be both simultaneous and dynamic. Section 2 describes procedures for obtaining Cox-type and encompassing tests for competing models estimated by GMM. Section 3 specializes these results to competing linear regression models estimated by instrumental variables; regression forms for the statistics are presented. The paper is concluded by Section 4. In our presentation, we eschew detailed regularity assumptions.
A Cross-calibrated, Multiplatform Ocean Surface Wind Velocity Product for Meteorological and Oceanographic Applications

Abstract The ocean surface wind mediates exchanges between the ocean and the atmosphere. These air–sea exchange processes are critical for understanding and predicting atmosphere, ocean, and wave phenomena on many time and space scales. A cross-calibrated multiplatform (CCMP) long-term data record of satellite ocean surface winds is available from 1987 to 2008 with planned extensions through 2012. A variational analysis method (VAM) is used to combine surface wind data derived from conventional and in situ sources and multiple satellites into a consistent nearglobal analysis at 25-km resolution, every 6 h. The input data are cross-calibrated wind speeds derived from the Special Sensor Microwave Imager (SSM/I; F08–F15), the Tropical Rainfall Measuring Mission Microwave Imager (TMI), and the Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E), and wind vectors from SeaWinds on the NASA Quick Scatterometer (QuikSCAT) and on the second Japanese Advanced Earth Observing Satellite (ADEOS-.
Electrical after-effects in Pb(Ti, Zr)O3 ceramics

Pb(Ti, Zr)O3 ceramics doped with Al, Mn or Fe exhibit constricted or asymmetrically displaced hysteresis loops. This distortion is due to an internal bias field Ei which can exceed the coercive field strength. Ei depends on the Ti/Zr ratio and on the kind of dope, and it increases with increasing doping concentration.After repeated cycling of the hysteresis loop the distortion disappears. This process, called “hysteresis relaxation,” obeys a time law of the form Ei(t) ∼exp(-t/τ)and is found to behave both like a field and thermally activated process. The activation energy of all investigated specimens doped with transition metal ions (Mn, Fe) lies between 0.6 and 0.7 eV, that of Al-doped samples is about 0.8 eV.Comparison of the behaviour of the dielectric and mechanical losses with that of the internal bias shows that these effects are closely correlated. From this correlation some conclusions can be drawn concerning the nature of Ei, the physical causes of the observed after-effects, and the influence o.
Applying fast multipole method to higher-order hierarchical legendre basis functions in electromagnetic scattering

The fast multipole method (FMM) is developed to analyse electromagnetic scattering using higher-order hierarchical Legendre basis functions, which have been proposed recently and make the impedance matrix, from method of moments, a low condition number. In this method, the point-to-point based-on-sample quadrature is used because the basis functions are defined on large surface patches of scatterers. The numerical implementations of matrix-vector multiply by FMM are particularly presented. These numerical results show that the proposed second- or third-order FMM (high-order FMM) is accurate and efficient.
Finding spiral structures in images of galaxies

Much recent work in statistical image analysis has been concerned with ‘cleaning’ images by a bayesian statistical analysis incorporating a prior model, which reflects the spatial structure of the image. In almost all cases this has involved a description of the image at pixel level. In this paper we take the process further, and develop a spatial stochastic process of objects present in the image. The general theory is given and applied to images of spiral galaxies, with the aims of producing better schematic reconstructions and of automatically classifying galaxies.
Understanding the Concept of "Division": Assessment Considerations

This article presents a summary of considerations for teachers when assessing a student's understanding of Division concepts. As with all mathematical concepts, children develop a basic idea of Division through interactions with others in daily life, beginning from the preschool years. As they move into elementary school, Division is introduced as an arithmetic operation, building on their prior knowledge of addition, subtraction, and multiplication. As children advance to middle school, various uses of fractional concepts are introduced, along with algorithms involving rational numbers. Although there is no clear demarcation as to the grade at which a more advanced level of understanding may be taught, for the purpose of discussion, this article is organized into three broad levels: Preschool, Elementary, and Middle School. Within each level, the assessment of (a) student products, (b) student procedures and strategies, and (c) student concepts and explanations, is presented. Examples of assessment activities and examples of possible student misconceptions are provided. The article concludes with a discussion of the assessment of teaching practices using Division as a model for other areas of mathematics.
Focal Mechanisms from Sparse Observations by Nonlinear Inversion of Amplitudes: Method and Tests on Synthetic and Real Data

Abstract The purpose of this article is to address the problem of the focal mechanism determination using few seismological records acquired by a sparse network of 3-component sensors. Such cases are frequently encountered in reservoir contexts for the monitoring of the fluid-induced microseismicity. Focal mechanisms of fluid-induced earthquakes are characterized by a non-double-couple part. However, we show and discuss that the double-couple moment tensor approximation is valid as a source model. Then, we propose a nonlinear inversion method of the direct P -, SV - and SH -wave amplitudes, based on a simulated annealing algorithm to determine double-couple focal mechanisms. Simultaneously, we determine the associated uncertainty. We take into account three sources of uncertainty related to the convergence process of the inversion to the amplitude picking uncertainty caused by the noise level and to the uncertainty of the event location. First, we test our method on synthetic data. Second, we apply the method on four events induced in the Soultz-sous-Forets geothermal field whose focal mechanisms were already determined by Charlety et al. (2007). We obtain focal mechanisms with uncertainties containing the solutions previously determined. Finally, we evaluate the required minimum number of sensors and their geometrical configuration to obtain a focal mechanism. The direction of the nodal planes and the type of mechanism are retrieved for data sets as small as three 3-component stations. The tests also reveal that the reliability of the fault plane solution depends on the configuration the stations used. It also seems that the coverage of the focal sphere by the stations, that is, the opening angle of the network and the coverage of several quadrants, has an influence on the reliability of the fault plane solution retrieval. The use of only one 3-component sensor allows retrieval of the type of focal mechanism in most of the cases studied.
Compound-Compressible Nozzle Flow

Abstract : A one-dimensional theory based upon fundamental flow relationships is presented for analyzing the behavior of one or more gas streams flowing through a single nozzle. This compound-compressible flow theory shows that the behavior of each stream is influenced by the presence of the other streams. The theory also shows that the behavior of compound-compressible flow is predicted by determining how changing conditions at the nozzle exit plane affect conditions within the nozzle. It is found that, when choking of the compound-compressible flow nozzle occurs, an interesting phenomenon exists. The compound-compressible flow is shown to be choked at the nozzle throat, although the individual stream Mach numbers there are not equal to one. This phenomenon is verified by a wave analysis which shows that, when choking occurs, a pressure wave cannot be propagated upstream to the nozzle throat even though some of the individual streams have Mach numbers less than one. Algebraic methods based on this compound-compressible flow theory are used to demonstrate the usefulness of this approach in computing the behavior of compound-compressible flow nozzles.
Ride quality and noise in high speed elevators

Ride quality in an elevator is the latest "hot topic" in elevator design and construction. In skyscrapers being built in Asia, Dubai and the US, the new elevators travel close to and beyond 10m/s. The rides to the highest floors will last well over one minute. From a comfort point of view, it is important that the ride be as smooth and quiet as possible. There are many factors that influence the vibration of the elevator and the concomitant noise. In this paper we will examine the sudden forces that the elevator experiences as it passes each floor. The side forces on the elevator are caused by the asymmetric flow field about the elevator cab. The pressure and streamline flow field was evaluated by using the CFD code FLUENT. Comparison between the numerical and the measured results are given and the pressure disturbances caused by the passage of the elevator and its appendages are discussed together with some solutions to alleviate the pressure disturbances.
On the Possibility of Describing Lattice Properties of Iridium in Terms of Pseudopotential Theory

The possibility is discussed of describing lattice properties of iridium in terms of pseudopotential perturbation theory with allowance for second and third order. Values of pseudopotential parameters are proposed which provide a good description of the lattice properties of iridium under zero pressure, the contributions of the three-ion forces being small. The total energy, pressure, elastic moduli, Debye temperature, low-temperature Gruneisen parameter, pairwise potentials, and also effective solid sphere packing parameters are calculated. In addition, by invoking molecular dynamic methods, the vacancy formation and migration energies and the stacking fault energies are computed. The electron energy spectrum and group velocity calculations suggest that the electron density of states curve of Ir exhibits no van Hove singularities near the Fermi level, a fact which apparently accounts for the successful description of lattice properties in terms of the pseudopotential perturbation theory. [Russian Text Ignored].
Thermohydraulic Modeling of Capillary Pumped Loop and Loop Heat Pipe

Capillary pumped loop (CPL) and loop heat pipe (LHP) are passive heat transport devices that are gaining importance as a part of the thermal control system of modern high power spacecraft. A mathematical model to simulate the thermohydraulic performance of CPLs and LHPs is required for the design of such a thermal control system. In this study a uniﬁed mathematical model to estimate thermal and hydraulic performance of a CPL and an LHP with a two-phase or a hard-ﬁlled reservoir is presented. The steady-state model is based on conservation of energy and mass in the system. Heat exchange between the loop and the surroundings and pressure drops in the loop are calculated. This study presents the results of numerical studies on a CPL and an LHP. The constant conductance regime in a CPL or an LHP occurs when the reservoir is hard-ﬁlled. It also occurs in an LHP if the condenser is fully used. The heat leak across the wick becomes signiﬁcant in a hard-ﬁlled LHP because the core is no longer saturated and hence the mass ﬂow rate must be calculated using an energy balance on the outer surface of the wick.
NMR Study of Antiferromagnetic a-Mn Metal

NMR study has been made on antiferromagnetic α-Mn metal at helium temperature in zero external field. NMR signal of Mn 55 from Site I appears at 199.4 MHz. The signal from Site II consists of two split lines and appears at 151.5 and 144.5 MHz. The signal from Site III has complicated structure and appears in the range from 20 to 35 MHz. The signal from Site IV appears at around 5 MHz. It is concluded that there are two types of magnetic moment on Site II. Except for this point, the results are consistent with the recent neutron diffraction study and support the non-collinear spin configuration. The appearance of two types of moment at Site II is discussed.
Evidence of enhanced electron-phonon coupling in ultrathin epitaxial copper films

Electron phonon (el-ph) coupling is a fundamental quantity that controls the electron transport through a conductor. We experimentally determined the el-ph coupling strength of epitaxial copper (Cu) films ranging from 5 to 1000 nm thick using both ultra-fast, optical pump-probe reflectivity and temperature-dependent resistivity measurements. An enhancement of the el-ph coupling strength was observed when the thickness of the films was reduced to below 50 nm. We suggest that this unexpected enhancement of the el-ph coupling strength is partially responsible for the observed increase of resistivity in the films below 50 nm thick.
Piecewise exponential estimator of the survivor function

A method for estimating the survivor function of a life distribution from a set of censored data is presented. The method is illustrated and it is explained how to calculate the survivor function from a censored data set. The estimator is compared with the well-known Kaplan-Meier estimator, using a set of data observed in a real engineering situation. The advantages and disadvantages of the method are discussed. >
Shared parameter models under random effects misspecification

A common objective in longitudinal studies is the investigation of the association structure between a longitudinal response process and the time to an event of interest. An attractive paradigm for the joint modelling of longitudinal and survival processes is the shared parameter framework, where a set of random effects is assumed to induce their interdependence. In this work, we propose an alternative parameterization for shared parameter models and investigate the effect of misspecifying the random effects distribution in the parameter estimates and their standard errors. Copyright 2008, Oxford University Press.