Miracle-dz/UniFAR-FTUs huggingface dataset:
What we can learn about the behavior of (cid:133)rms from the average monthly frequency of price-changes: an application to the UK CPI data. (cid:3)

The monthly frequency of price-changes is a prominent feature of many studies of the CPI micro-data. In this paper, we see what the frequency implies for the behavior of price-setters in terms of the cross-sectional distribution average of price-spell durations across (cid:133)rms. We derive a lower bound for the mean duration of price-spells averaged across (cid:133)rms. We use the UK CPI data at the aggregate and sectoral level and (cid:133)nd that the actual mean is about twice the theoretical minimum consistent with the observed frequency. We construct hypothetical Bernoulli-Calvo distributions from the frequency data which we (cid:133)nd can result in similar impulse responses to the estimated hazards when used in the Smets-Wouters (2003) model. JEL: E50
Lectures on attractors and black holes

A basic survey on some aspects of four‐dimensional black holes (BHs) is given in these lectures. It covers thermodynamical properties as well as the Attractor Mechanism for extremal BHs in an environment of scalar field background. Some relevant formulæ for the critical points of the BH “effective potential” are discussed, and the simplest example uncovering the attractor behavior, the Maxwell‐Einstein‐dilaton supergravity, is analyzed in detail. Observations on similarities between BH entropy (as given by the Bekenstein‐Hawking entropy‐area formula) and multipartite entanglement of qubits in quantum information theory are reported, as well. Finally, among the latest developments, the moduli space of attractor points for 𝒩 ≥ 2 supergravities is also considered. Based on lectures given by S. Ferrara at the International School of Subnuclear Physics, 45th Course: Search for the “Totally Unexpected” in the LHC era, Erice, Italy, 29 August – 7 September 2007 (Directors: G. 't Hooft – A. Zichichi), and at the III Avogadro Meeting on Theoretical Physics, Alessandria, Italy, 19 – 21 December 2007.
LONGITUDINAL DRIFTS OF STREAMERS ACROSS THE HELIOSPHERIC CURRENT SHEET

Potential field source surface (PFSS) extrapolations of the photospheric magnetic field provide a qualitatively correct model of the coronal magnetic structure. We show that the magnetic structure provided by PFSS describes a framework within which high-density coronal streamers are distributed. However, the density structures have considerable freedom to drift longitudinally along the magnetic structure. Some caution must therefore be taken when using PFSS models as proxies for the coronal density structure. In particular, while measurements of coronal rotation using PFSS models provide an estimate of the large-scale magnetic structure rotation, they are not valid measurements of the density rotation. Furthermore, attempts to assign a consistent rate of rotation to the electron corona over long time periods are not always valid since the movement is dominated by structural reconfiguration. These conclusions are reached by the application of solar rotational tomography to LASCO C2/Solar and Heliospheric Observatory observations during solar minimum (1996–1997), revealing the changing density structure of the equatorial streamer belt at a height of 4 R☉.
Costly participation and default allocations in all-pay contests

Some important forms of contests have participation costs and ‘default allocations’ where the contest prize is still awarded even when no-one actively competes. We solve a general, all-pay contest model that allows for ﬂexible forms of these features under arbitrary asymmetry. We then use our framework to better connect the literatures on contests and sales price competition, and use this connection to solve some long-standing problems. Finally, we analyze how participation costs and default allocations can be used as novel, practical tools in contest design. Throughout, the combined presence of participation costs and default allocations often reverse otherwise familiar intuitions
The Spatial Coherence of African Rainfall Anomalies: Interhemispheric Teleconnections

Abstract The spatial patterns of rainfall variability over the African continent are examined using a regionally averaged data set comprising the records of 1087 stations. Typical rainfall departure patterns, or anomaly types, are derived using a linear correlation method to assess the similarity of annual departure maps for the years 1901 to 1973. For the region north of the equator, most years fall into one of six types, four of which show a strong opposition between equatorial and subtropical latitudes and two of which show departures of the same sign over the whole region. For the continent as a whole, six types are also derived. These reflect the patterns derived using northern Africa alone, with conditions in the southern subtropics resembling those in subtropical latitudes north of the equator. Continentally, two principal spatial patterns of rainfall variation are evident: anomalies of the same sign over most of Africa and anomalies of the opposite sign in equatorial and subtropical latitudes. Thu.
Structure and evolution of very close binary systems. I - Structure equations including rotational and tidal distortions and calculations for 2, 1, and 0.65 solar-mass zero-age main-sequence stars

A method is developed which allows an efficient and accurate investigation of the structure and evolution of a rotationally and tidally distorted star in a close binary system. The method involves no division into different approximation regimes, and the structure equations are written in essentially the same form as the one for spherical stars. The explicit effects of the distortions are included through basically just one correction factor which can be readily calculated. We also discuss in some detail the envelope integration in the case of superradiabatic convection. Models for zero-age main-sequence stars of 2, 1, and 0.65 M/sub sun/ are computed as a check on our formulation and compared with those obtained using other methods.
HUBBLE SPACE TELESCOPE Photometry of the Globular Cluster M4

This paper presents a detailed description of the acquisition and processing of a large body of imaging data for three fields in the globular cluster M4 taken with the Wide Field and Planetary Camera 2 aboard the Hubble Space Telescope. Analysis with the ALLFRAME package yielded the deepest photometry yet obtained for this cluster. The resulting data set for 4708 stars (positions and calibrated photometry in V, I, and, in two fields, U) spanning approximately six cluster core radii is presented. The scientific analysis is deferred to three companion papers, which investigate the significant white dwarf population discovered and the main-sequence population.
Stochastic modeling of large‐scale transient unsaturated flow systems

A new framework for modeling large-scale transient unsaturated flow systems in spatially variable soils is proposed in order to overcome the problem of limited information about the local details of spatial soil variability. A stochastic approach, which assumes that local soil properties are realizations of three-dimensional random fields, is followed for derivation of a large-scale model representation (structure). The three dimensionality of the local flow and the nonlinear dependence of the local flow output on the local soil properties are considered. The large-scale model structure is derived by averaging the local governing flow equation over the ensemble of realizations of the underlying soil property random fields. The resulting mean model representation is in the form of a partial differential equation in which averaged or effective model parameters occur. These effective model parameters (i.e., effective hydraulic conductivity and effective specific moisture capacity) are evaluated using a quasi-linearized fluctuation equation and a spectral representation of stationary processes. The large-scale model representation considers the large-scale effects of soil property variability and has relatively few parameters. The general conclusions of this study are that soil property variability produces large-scale hysteresis and anisotropy of the effective parameters. The potential theoretical and practical ramifications of these results in the area of unsaturated flow modeling need to be investigated. The general stochastic modeling framework developed here is applicable not only to unsaturated flow but also to other distributed parameter systems (e.g., saturated flow and transport, geothermal and oil reservoir modeling).
Lyman break galaxies at z= 4–6 in cosmological smoothed particle hydrodynamics simulations

We perform a spectrophotometric analysis of galaxies at redshifts z = 4-6 in cosmological smoothed particle hydrodynamics simulations of a A cold dark matter universe. Our models include radiative cooling and heating by a uniform ultraviolet (UV) background, star formation, supernova feedback, and a phenomenological model for galactic winds. Analysing a series of simulations of varying box size and particle number allows us to isolate the impact of numerical resolution on our results. Specifically, we determine the luminosity functions in B, V, R, i' and z' filters, and compare the results with observational surveys of Lyman break galaxies (LBGs) performed with the Subaru telescope and the Hubble Space Telescope. We find that the simulated galaxies have UV colours consistent with observations and fall in the expected region of the colour-colour diagrams used by the Subaru group. The stellar masses of the most massive galaxies in our largest simulation increase their stellar mass from M * ∼ 10 11 M ⊙ at z = 6 to M * ∼10 11.7 M ⊙ at z = 3. Assuming a uniform extinction of E(B- V) = 0.15, we also find reasonable agreement between simulations and observations in the space density of UV bright galaxies at z = 3-6, down to the magnitude limit of each survey. For the same moderate extinction level of E(B - V) ∼0.15, the simulated luminosity functions match observational data, but have a steep faint-end slope with a ∼-2.0. We discuss the implications of the steep faint-end slope found in the simulations. Our results confirm the generic conclusion from earlier numerical studies that UV bright LBGs at z ≥ 3 are the most massive galaxies with E(B - V) ∼0.15 at each epoch.
Radio emission from the nova-like variable AC Cancri and the symbiotic variable AG Draconis

Radio emission at 6 cm has been detected from the nova-like cataclysmic variable AC Cnc and the symbiotic variable AG Dra. The AC Cnc observation constitutes the first radio detection in this class of objects. The AG Dra source is probably resolved and appears to show asymmetric, extended structure. The radio emission can best be explained by thermal bremsstrahlung. 26 references.
Current Induced Second Harmonic Generation in Semiconductors

Second order nonlinear optical effects have been thoroughly studied and used ever since the very first experiment in the early 1960’s It is also well known that only materials lacking the center of inversion symmetry possess the second order susceptibility χ(2)[1]. At the same time, externally applied fields can break the symmetry and cause the so-called field induced second order susceptibility. For example, this effect is believed to be behind the “seeded” second harmonic generation (SHG) in glass fibers where external field is produced by space charge [2]. In insulating materials it is not difficult to apply external fields high enough to produce appreciable χ(2), One can then envision that this DC-induced SHG can be used to probe and map the distribution of the electric field. But what about the metals and semiconductors, where the electric fields are small while the currents can be quite strong? Here, using simple two-band model, we show that in the presence of a direct current a second order nonlinear susceptibility, proportional to the current exists.
Subspaces, angles and pairs of orthogonal projections

We give a new proof for the Wedin theorem on the simultaneous unitary similarity transformation of two orthogonal projections and show that it is equivalent to Halmos' theorem on the unitary equivalence of projection pairs. As a consequence of these theorems, we derive several results on pairs of orthogonal projections, relative subspace positions and oblique projections as well.
Internal wave reflexion from a sinusoidally corrugated surface

The reflexion of an internal gravity wave with stream function \[ \psi = \exp\{i(kx + lz - \omega t)\} \] from a corrugated surface of the form z = a cos px is investigated using an extension of Rayleigh's method for an inviscid non-diffusive fluid. It is found that the method converges for many wall slopes ap and incoming-wave phase propagation incidence angles θ = tan−1 l/k but that the appropriate series solution is only asymptotic in other cases. The accuracy of the calculations is assured by requiring that the solution satisfy the boundary condition at the wall using a least-squares error minimization technique. The accuracy is then verified through the conservation of energy flux. It is found that, as the surface slope is increased for constant θ, less energy appears in specular reflexions and more is either back-scattered or redistributed into other forward-scattered modes. As the horizontal internal wavelength is decreased to become comparable to the corrugation wavelength of the wall, substantially less energy appears in specular reflexion, but of the order of 95% of the incoming energy is specularly reflected for 30° < θ < 60° when the two wavelengths are equal. In contrast to this, it is found that the general level of the ratio of back-scattered to forward-scattered energy is reduced by O(10−3) to O(10−2) as the incident horizontal internal wavelength becomes smaller than the corrugation wavelength. The results are compared with the linear theory of Baines (1971); agreement is good for forward-scattered energy and excellent for the back-scattered flux when p ≥ k.
On The Use Of Variable Coherence In Inverse Scattering Problems

Even though most of the properties of optical elds, such as wavelength, polarization, wavefront curvature or angular spectrum, have been commonly manipulated in a variety of remote sensing procedures, controlling the degree of coherence of light did not nd wide applications until recently. Since the emergence of optical coherence tomography, a growing number of scattering techniques have relied on temporal coherence gating which provides e¢ cient target selectivity in a way achieved only by bulky short pulse measurements. The spatial counterpart of temporal coherence, however, has barely been exploited in sensing applications. This dissertation examines, in di¤erent scattering regimes, a variety of inverse scattering problems based on variable spatial coherence gating. Within the framework of the radiative transfer theory, this dissertation demonstrates that the short range correlation properties of a medium under test can be recovered by varying the size of the coherence volume of an illuminating beam. Nonetheless, the radiative transfer formalism does not account for long range correlations and current methods for retrieving the correlation function of the complex susceptibility require cumbersome cross-spectral density measurements. Instead, a variable coherence tomographic procedure is proposed where spatial coherence gating is used to probe the structural properties of single scattering media over an extended volume and with a very simple detection system. Enhanced backscattering is a coherent phenomenon that survives strong multiple scattering. The variable coherence tomography approach is extended in this context to di¤usive
Extended Bandwidth Zero Phase Error Tracking Control of Nonminimal Phase Systems

This paper describes a new feedforward algorithm for accurate tracking control of nonminimal phase systems. Accurate feedforward calculation involves a prefilter design using the inverse system model. Nonminimal phase systems cause problems with this prefilter design, because unstable zeros become unstable poles in the inverse model. The zero phase error tracking control algorithm (ZPETC) consists of a substitution scheme, which removes the unstable zeros
The blue straggler star population in NGC 6229

We have used a combination of high-resolution Hubble Space Telescope Wide Field Planetary Camera 2 and wide-field ground-based observations in ultraviolet and optical bands to study the blue straggler star (BSS) population of the outer halo globular cluster NGC 6229 over its entire radial extent. A total of 64 bright BSS (with m255≤ 21.30, corresponding to m555≤ 20.75) has been identified. The BSS-projected radial distribution is found to be bimodal, with a high central peak, a well-defined minimum at intermediate radii (r∼ 40 arcsec) and an upturn in the outskirts. From detailed star counts even in the very inner region, we compute the centre of gravity of the cluster and the most accurate and extended radial density profile ever published for this system. The profile is reasonably well reproduced by a standard King model with an extended core (rc≃ 9.5 arcsec) and a modest value of the concentration parameter (c≃ 1.49). However, a deviation from the model is noted in the most external region of the cluster (at r > 250 arcsec from the centre). This feature needs to be further investigated in order to assess the possible presence of a tidal tail in this cluster.
Instabilities and nonradial motion in SN 1987A

Detailed numerical calculations of relatively high resolution are reported which show that shock propagation through realistic presupernova structrue results in a pronounced Rayleigh-Taylor instability. Processed matter is found to penetrate near to the H-He interface after only 10,000 seconds, well before significant decay of Ni-56. Pronounced fingers forming in density, though not in temperature, are also found. Such behavior has profound implications for line formation, polarimetry, and X-ray and gamma-ray emission from SN 1987A and for subsequent development of the Ni-Co bubble. 38 refs.
Electron-impact-ionization cross sections for excited states of B{sup q+} (q=0-2) and an investigation into n scaling of ionization cross sections

Nonperturbative R-matrix-with-pseudostates (RMPS) and time-dependent close-coupling (TDCC) methods are used to determine electron-impact-ionization cross sections for the excited states of B, B{sup +}, and B{sup 2+}. RMPS calculated cross sections are presented for the 1s{sup 2}2s{sup 2}3l and 1s{sup 2}2s{sup 2}4l configurations of B, the 1s{sup 2}2s3l and 1s{sup 2}2s4l configurations of B{sup +}, and the 1s{sup 2}3l, 1s{sup 2}4l, and 1s{sup 2}5l configurations of B{sup 2+}. It is shown that the TDCC-calculated cross sections for the 1s{sup 2}2s{sup 2}3s configuration of B, the 1s{sup 2}2s3s configuration of B{sup +}, and the 1s{sup 2}3s configuration of B{sup 2+} are in reasonable agreement with the RMPS results. Furthermore, n scaling of these nonperturbative cross sections is investigated and a scheme proposed to allow for the extrapolation of electron-impact-ionization cross sections to higher n shells. Two semiempirical ionization cross-section expressions are fitted to the peak of the highest n-bundled RMPS cross sections for B, B{sup +}, and B{sup 2+}. These are subsequently used for accurate evaluation of the higher n-shell ionization cross sections needed to obtain temperature- and density-dependent generalized collisional-radiative ionization coefficients for the impurity and transport modeling of magnetic fusion plasmas.
A Composite Life Cycle of Nonsquall Mesoscale Convective Systems over the Tropical Ocean. Part II: Heat and Moisture Budgets

Abstract The heat and moisture budgets associated with five large nonsquall cloud clusters observed during Phase 3 of the Global Atmospheric Research Program's Atlantic Tropical Experiment (GATE) are investigated. The input data for the budget computations are objectively analyzed fields of wind, temperature and relative humidity that were based on conventional upper-air soundings. Estimates of the radiative heating rate were obtained from Cox and Griffith. A compositing technique is used to summarize the budget results for the growing, mature and dissipating stages of the clusters. The budgets in the growing stage are characterized by a very large low-level, apparent moisture sink separated in height from the region where the apparent heating is realized. In the mature stage, the apparent heating maximum shifts upward, accompanied by the development of a corresponding secondary maximum of apparent drying. A composite of radiative heating estimates from Cox and Griffith shows that the horizontal radiative.
Nonparametric Identification of Nonlinear Time Series: Projections

Abstract We study the possibility of identifying general linear and nonlinear time series models using nonparametric methods. The kernel estimators of the conditional mean and variance are used as a basis, and the properties of these quantities as model indicators are briefly discussed. Some drawbacks are pointed out, and motivated by these we introduce projections as tools of identification. The projections are especially useful for additive modeling. Expressions for the asymptotic bias and variance are obtained. The projection of the conditional variance is suggested as a tool for identifying heteroscedastic time series. The results are illustrated by simulations for both the estimators of the projections and the estimators of the conditional mean and variance.
The effects of fatigue on acoustic nonlinearity in aluminum alloys

Experimental evidence is presented which suggests a strong nonlinear interaction of acoustic waves with dislocation dipoles in fatigued metals. A recently formulated model of the interaction of an acoustic wave with dislocation dipoles and dipole-array approximations to veins and persistent slip bands (substructures) formed during metal fatigue is examined. The model predicts the generation of a substantial acoustic second harmonic that depends on the distance between the glide planes of the dipole pair, on the dipole density, and on the particular arrangement and volume fraction of dipoles in a given substructure of the fatigued solid. Experimental evidence which strongly supports the essential features of the theoretical model is presented for fatigued aluminium alloy 2024-T4. The effects of artificial aging on acoustic harmonic generation and on fatigue-induced microstructural features in precipitation-hardened Al 2024 are discussed. <<ETX>>
Thermal Post-Buckling Analysis of Nanoscale Films Based on a Non-Classical Finite Element Approach

A size-dependent finite element (FE) formulation including surface free energy effect is developed in this article to study the post-buckling behavior of nanofilms under the action of thermal loads. The Gurtin-Murdoch surface elasticity theory is utilized to consider the surface effects. Moreover, the principle of virtual work is used so as to derive the equilibrium equations. The proposed FE formulation is based on the first-order shear deformation theory (FSDT). The von Kármán nonlinear relations are also employed to take the geometric nonlinearity into account. After deriving the FE equations, the resulting set of parameterized non-linear equations is solved using the pseudo arc-length continuation algorithm, and bifurcation diagrams of nanofilms are obtained. Selected numerical results are presented for the influences of surface stress on the thermal post-buckling characteristics of nanofilms subject to different types of boundary conditions.