Miracle-dz/UniFAR-FTUs huggingface dataset:
The three types of high-mass X-ray pulsator

High mass X-ray pulsators are shown to be divisible into three distinct groups on the basis of their observational properties: 1) the Be star systems, 2) non-Be star systems with long pulse periods, (~102 — 103 s), and 3) non-Be star systems with short pulse periods (~100 — 101 s). Differences in mass transfer processes between the groups are invoked to account for the different properties. The separation of high mass pulsators into three clearly defined groups enables some of the properties of a pulsator to be predicted if only a few of its parameters are known. Because of this the optical counterparts of the X-ray sources H0850-42, OAO1653-40 and 1E1048.1-5937 are predicted to be either Be stars or, much less likely, low mass binaries. The orbital (Po) and spin (Ps) periods of the short period systems may be anti-correlated, a phenomenon which is also exhibited by the intermediate polar white dwarf binaries. For the long period systems there is no strong relationship between Po and Ps as there is for the Be star systems. It is shown that for the Be star systems this relationship cannot be accounted for by accretion from a stellar wind if there is equality between the Alfven and corotation radii of the neutron stars in these systems. However, accretion from a non-expanding atmosphere is not excluded. The lack of any correlation between Ps and Po for the supergiant systems is attributed to the low angular momentum of accreted matter. The Be star systems, however, probably accrete significant angular momentum which can result in an accretion disk.
Enhanced thermoelectric figure of merit in nanostructured ZnO by nanojunction effect

We report in this letter the synthesis and thermoelectric properties of Zn1−xNixO/polyparaphenylene (Zn1−xNixO/PPP) organic-inorganic hybrid materials. Compared to the inorganic ZnO-based materials, hybrid materials exhibit dual effects of increased power factor consistent with the molecular junction effect and a reduction in thermal conductivity by the incorporation of conductive PPP. As a result, the greatest ZT = 0.54 of hybrid materials was obtained at 1173 K, which corresponds to a 6-fold enhancement compared to that of the best inorganic Zn0.97Ni0. 03O sample (ZT = 0.09) at 1000 K.
Determination of parameters of a hypoplastic constitutive model from properties of grain assemblies

The stress–strain behaviour of granular materials can be modelled with hypoplastic constitutive relations. A hypoplastic model is briefly introduced for the axially symmetric case, and a procedure for the determination of its parameters is described in detail. It is shown, for several sands and one gravel, that all parameters of the hypoplastic model are closely related to the granulometric properties of grain assemblies. Recalculations of some element tests are presented in order to verify the proposed procedure. Copyright © 1999 John Wiley & Sons, Ltd.
Photoluminescence of carbon-implanted GaAs

The 5‐K photoluminescence (PL) spectra of undoped semi‐insulating GaAs are observed as a function of carbon implantation dose (after 850°C annealing using a SiO2 cap). Results show that although the intensity of the bound exciton line at 1.514 eV remains fairly independent of carbon concentration up to 1017 cm−3 carbon, the intensity of the conduction band to acceptor peak at ∼1.494 eV increases monotonically with carbon implant dose. This is the first direct confirmation that the 1.494‐eV transition is due to carbon. The observed correlation between implanted carbon doses and PL intensities at high excitation levels is the basis of an analytic technique for C assessment in GaAs.
Dynamics of vertical-cavity surface-emitting lasers with optical injection: a two-mode model approach

We present a comprehensive study of the bifurcation routes in a generic model of a two-polarization-mode semiconductor laser when subject to orthogonal optical injection, relevant to a single-transverse-mode vertical-cavity surface-emitting laser. For positive detunings, polarization switching (PS) occurs as the intensity of the noninjected mode gradually decreases and eventually shuts down, in some cases accompanied along the way by the onset and the subsequent vanishing of relaxation oscillations. We identify a Hopf bifurcation on a two-polarization-mode solution, which supports the onset of relaxation oscillation time-periodic dynamics in both injected (x-linearly polarized) and noninjected (y-linearly polarized) modes. For sufficiently large negative detunings, PS is a sharp transition occurring either at the injection-locking point or at a subcritical Hopf bifurcation and is often part of a hysteresis cycle.
Analytical solution of a convection‐dispersion model with time‐dependent transport coefficients

Mathematical studies of solute transport in porous media have often utilized “equivalent” models of the transport process to remove undesired variability in the transport coefficients at the space and time scales of direct interest. Both deterministic and stochastic approaches in this genre produce an “effective” convection- dispersion equation with time-dependent coefficients. This type of equation in one spatial dimension is investigated mathematically in the present paper. A closed-form solution of the solute transport equation is derived for a semi- infinite spatial domain with arbitrary initial and boundary flux conditions. It is shown that the solution reduces to well-known results for special forms of the time-dependent coefficients. In general, however, a Volterra integral equation of the second kind must be solved to evaluate the analytical solution of the transport equation. We present a stable and convergent numerical scheme, utilizing a trapezoidal quadrature rule, for the solution of the Volterra equation. The method of solution developed should be applicable to a broad variety of solute transport problems, including particularly those in heterogeneous porous media.
Generalized Data Reduction For Heterodyne Interferometry

A generalized algorithm for use with digital heterodyne or fringe- scanning interferometers was developed that removes many of the restrictions that had previously applied to the data collection scheme. The required phase steps may be chosen with unequal spacing and to extend over a range greater than 2w. The integrating-bucket and phase-step approaches produce identical results.
Bootstrapping Numeral Meanings and the Origin of Exactness

How do children learn the meanings of number words like one, two, and three? Whereas many words that children learn in early acquisition denote individual things and their properties (e.g., cats, colors, shapes), numerals, like quantifiers, denote the properties of sets. Unlike quantifiers such as several and many, numerals denote precise quantities. Further, numerals form an unbounded list and denote a potentially infinite set of quantities. On these grounds, they would appear to constitute a unique learning problem to children acquiring language, quite distinct from the problem of learning nouns or verbs. Despite these important differences between numerals and other words, researchers such as Syrett, Musolino, and Gelman (this issue) have converged on the idea that some of the more difficult problems that they pose in acquisition might be explained by previously attested word learning mechanisms. Following Bloom and Wynn (1997) and others (Barner, Libenson, Cheung, & Takasaki, 2009; Carey, 2009; Sarnecka, Kamenskaya, Yamana, Ogura, & Yudovina, 2007), Syrett et al. examine the role of syntactic bootstrapping in discovering numeral meanings. Other studies have looked at mechanisms like the whole object constraint, the principle of contrast, and Gricean implicature in number word learning (see Sullivan & Barner, 2011, for review). Studies like these bring into question whether specialized domain-specific mechanisms are required to explain number word learning and raise the possibility the idea that numerals are more similar to other words than sometimes supposed. The case of syntactic bootstrapping has received particular attention in recent years yet has been accompanied by relatively little experimental evidence. Syrett et al. attempt to rectify this by conducting a set of three experiments in addition to performing a detailed corpus analysis. The goal of their study was to differentiate several possible theories of how syntactic cues might
Error-correcting codes for multiple-level transmission

A q-level alphabet is defined as a row vector space over a finite field with q elements. The letters of the alphabet are the rows of the vector space, each consisting of n symbols from the ground field. The weight of a letter is the number of nonzero symbols it contains. The minimum weight of the letters of the alphabet, excluding zero, is denoted by d. A relationship is established between the alphabet and a set of points S in a finite projective space. There is a many-one correspondence between the letters of the alphabet and the hyperplanes of the space. The weight of a letter is simply related to the incidence of the set S with the corresponding hyperplane. Two sets of points in a finite projective space are called equivalent if they are related by a collineation of the space. Two alphabets are called equivalent if there exists between them, as vector spaces, a weight-preserving semi-isomorphism. It is shown that these definitions mean the same thing and reduce to the usual definition when q = 2. An inequality is established between the dimension of the alphabet and the parameters d, q, n. This gives a lower bound for n in terms of the other parameters. It is shown that this bound cannot be achieved by alphabets with repeated columns. A method is given for constructing a class of alphabets which attain this bound. It is shown that for the case q = 2 these are the only alphabets (in the sense of equivalence) for which the bound is attained.
Building blocks of amorphous Ge2Sb2Te5

The structural changes during the phase change between the amorphous and crystalline phase in Ge2Sb2Te5 have been the subject of intense study due to the importance of Ge2Sb2Te5 in phase change memory devices. In our study, the energetics of the transition between the crystalline and the amorphous phase of Ge2Sb2Te5 is explored using density functional theory DFT calculations, electron diffraction, and reverse Monte Carlo model refinement. No energy barrier was found between the crystalline and the previously suggested amorphous structure of Ge2Sb2Te5. Further DFT calculations have led to a different building block of the amorphous structure, which is shown to agree with the experimental reduced density function determined from electron diffraction experiments and previously reported extended x-ray absorption fine structure measurements.
Observational neutrino astrophysics

Neutrinos have been an important feature of theories of stellar processes for many decades. As a star forms from interstellar matter, its temperature gradually increases because of its gravitational contraction. However, this thermal energy is not sufficient to make it shine for long. We believe that the primary energy source of the Sun, and of stars in general, is a series of nuclear fusion reactions, occurring deep inside the star, in which energy is released as four protons are converted into a helium nucleus. In the process, two protons are converted into neutrons by each emitting a positron and an electron neutrino. Thus a star must emit electron neutrinos constantly.
Explicit FV Scheme for the Perona-Malik Equation

Abstract The Perona|Malik equation for nonlinear di®usion is the well-known equation widely used in image processing. This equation can be applied with great success for selective smoothing of images, where the noise is represented by small gradients and the spurious edges are represented by the large ones. For a numerical solution of this equation we use the ¯nite volume method. We analyze convergence of a corresponding explicit finite volume scheme to its weak solution and show some numerical experiments. We suggest also some modi¯cations of this scheme to obtain better CPU time performance of the algorithm.
Testing the presence of lithium on the surfaces of cool Ap stars

The possibility of a quite high Li abundance in the Ap stars was first raised by Wallerstein & Merchant (1965). Since then many studies investigated the problem of Li. The more recent observations in the lithium region indicate that in some Ap stars the $\lambda 6708$ feature is variable and this variability can be explained by the existence of Li rich spots on the stellar surface. Atomic data for the Ce II $\lambda 6708.099$ were released by the D.R. E.A.M. database in 2002. The line was used to identify the prominent suspected Li-feature in post AGB stars and might as well be responsible for the absorption feature in Ap stars. Recent studies have mentioned this possibility, but it has yet to be investigated in more detail. Other physical phenomena, such as the occurrence of a partial Paschen-Back effect in the presence of magnetic fields, as well as possible hyperfine structure splitting of some Rare Earth transitions, must be taken into account to provide correct line identifications in the wavelength region around the Li-doublet at $\lambda 6708$. We discuss a possible strategy to clarify the presence of Li in Ap stars.To search for other articles by the author(s) go to: http://adsabs.harvard. edu/abstract_service. html
The Transformation of Tropical Storm Agnes into an Extratropical Cyclone. Part I: The Observed Fields and Vertical Motion Computations

Abstract This is the first of two papers dealing with the transformation of tropical storm Agnes (June 1972) into an extratropical cyclone. Synoptic analyses and vertical motion patterns are used to describe the behavior of Agnes over a five-day period subsequent to initial landfall during which time Agnes regained tropical storm strength prior to transforming into an extratropical cyclone and dissipating. Input data for all calculations are obtained from optimum interpolation objective analyses with a resolution of 1° latitude-longitude in the horizontal and 100 mb in the vertical. A modified, 9-level version of Krishnamurti's (1968a) diagnostic balance model is discussed and applied to the data set to determine the fields of vertical motion. Redevelopment of Agnes subsequent to initial landfall is the result of the spread of an area of appreciable cyclonic vorticity advection aloft over the periphery of the low-level circulation devoid of significant baroclinicity. Unlike a corresponding midlatitude sto.
Langer–Cherry derivation of the multi-instanton expansion for the symmetric double well

The multi-instanton expansion for the eigenvalues of the symmetric double well is derived using a Langer–Cherry uniform asymptotic expansion of the solution of the corresponding Schrodinger equation. The Langer–Cherry expansion is anchored to either one of the minima of the potential, and by construction has the correct asymptotic behavior at large distance, while the quantization condition amounts to imposing the even or odd parity of the wave function. This method leads to an efficient algorithm for the calculation to virtually any desired order of all the exponentially small series of the multi-instanton expansion, and with trivial modifications can also be used for nonsymmetric double wells.
Dark current filtering in unipolar barrier infrared detectors

Control of dark current mechanisms is essential to improving the performance of infrared photodetectors and many other electronic devices. Unipolar barriers can readily be applied to practically and efficiently filter out multiple dark current components exhibited by infrared photodetectors. Via careful placement of unipolar barriers in a standard photodetector architecture, effective suppression of dark currents due to surface leakage, direct band-to-band tunneling, trap-assisted tunneling, and Shockley-Read-Hall generation is demonstrated. We present unipolar barrier photodiodes exhibiting six orders of magnitude improvement in RoA and near Auger-limited device performance.
On convergence of block-centered finite differences for elliptic-problems

We consider linear, selfadjoint, elliptic problems with Neumann boundary conditions in rectangular domains. We demonstrate that with sufficiently smooth data, the discrete $L^2 $-norm errors for tensor product block-centered finite differences in both the approximate solution and its first derivatives are second-order for all nonuniform grids. Extensions to nonselfadjoint and parabolic problems are discussed.
Study of the localized vibrations of boron in heavily doped Si

We have studied the localized vibrational modes of boron in heavily doped Si using Raman scattering for carrier concentrations of 5\ifmmode\times\else\texttimes\fi{}${10}^{18}$ to 1.5\ifmmode\times\else\texttimes\fi{}${10}^{20}$ ${\mathrm{cm}}^{\ensuremath{-}3}$. The line shapes and positions of the local mode and optic-phonon spectra due to interaction with the intervalence band continuum of electronic transitions are studied for different exciting frequencies. The local mode was also examined under uniaxial stress and was found to behave in a fashion similar to that of the optic phonon except for a larger hydrostatic shift, which seems due to the larger local compressibility in the region of the smaller boron atom.
DNA electrophoresis in microfabricated devices

Publications Jia Ou, Jaeseol Cho, Daniel W. Olson and Kevin D. Dorfman, “DNA Electrophoresis in a Sparse Ordered Post Array,” Physical Review E 79, 061904 (2009). Jia Ou, Samuel J. Carpenter and Kevin D. Dorfman, “Onset of Channeling during DNA Electrophoresis in a Sparse Ordered Post Array,” Biomicrofluidics 4, 013203 (2010) Noritoshi Araki, Eray S. Aydil and Kevin D. Dorfman, “Collision of a Long DNA Molecule with an Isolated Nanowire,” Electrophoresis 31, 3675-3680 (2010). Jia Ou, Mark N. Jowsiak, Samuel J. Carpenter and Kevin D. Dorfman, “Plasma Thinned Nanopost Arrays for DNA Electrophoresis,” Journal of Vacuum Science and Technology A 29, 011025 (2011). MAJOR OBSERVATIONS Elucidated the role of the curved field lines on DNA dynamics and demonstrated the ability to separate DNA in sparse, ordered post arrays. Developed a method to fabricate sparse arrays of nanoposts without the need for conventional nanopatterning steps (e.g., e-beam lithography). Developed a method to selectively grow ZnO nanowires into a separation microchannel. Studied the collision of a single DNA molecule with an isolated small post, confirming theoretical predictions.
Berry phases for many-spin systems with anisotropy exchange interaction in a strong magnetic field

An approximate instantaneous eigenstate is presented for the many-spin system possessing the anisotropy exchange interaction in a strong magnetic field by the perturbation method. Based on the instantaneous eigenstate, the Berry phase of this state is worked out. Furthermore, the effect of the anisotropy exchange interaction on the Berry phase of the state for the many-spin system is studied.
Investigation on interface related charge trap and loss characteristics of high-k based trapping structures by electrostatic force microscopy

Charge trap and loss characteristics of high-k based trapping layer structures are investigated by electrostatic force microscopy, which proves that the interfaces provide dominate trap sites. The effects of post-deposition anneal of HfO2 and Al2O3 single layer are determined. Based on aforementioned findings, we demonstrate the HfO2/Al2O3 bi-layers trapping structure with improved performance. The lateral charge spreading properties are also evaluated by extracted diffusion coefficients to further understand the interface effect. The study may provide insights into fundamental assessment and optimization for charge trapping structures, especially for high-density NAND flash applications.
From positive to negative magnetoresistance in graphene with increasing disorder

Artificial disorder was introduced gradually into monolayer graphene by controlling Ga+ ion irradiation and the corresponding electronic transport properties regulated by gate voltage, source-drain voltage, temperature, and magnetic field were studied experimentally. An unsaturated positive magnetoresistance (MR) up to 100% at ∼5 T was observed in as-fabricated graphene, while there is significant negative MR in disordered graphene. This phenomenon was attributed to the monocrystalline breaking and crystallite-boundary scattering in disordered graphene.
The angular momentum problem and magnetic braking - an exact time-dependent solution

A cylindrical cloud of uniform density rho/sub cl/ is imparted an initial angular velocity about its axis of symmetry with respect to the external medium of uniform density rho/sub ext/. A frozen-in magnetic field, initially radial and perpendicular to the axis of symmetry, links the two media. The angular velocity of the cloud is then calculated as a function of time for different ratios rho/sub cl//rho/sub ext/, representing different stages of contraction. Magnetic braking becomes more efficient as rho/sub cl//rho/sub ext/ (the only free parameter in the equations) increases. This is due to a decrease of the cloud's moment of inertia and an increase of the Alfven velocity in the neighborhood of the cloud upon contraction. A cloud with mass 10/sup 3/ M/sub sun/ and density 10/sup 3/ cm/sup -3/ which formed in a background field of 3 microgauss reduces its angular momentum by more than two orders of magnitude in less than 10/sup 6/ yr.The angular velocity, the shape of field lines, and the magnetic field of the external medium are calculated as functions of space and time. The initial rotational discontinuity propagates outward, setting into rotational motion matter farther and farther away from the axis. When a momentmore » of inertia comparable to that of the cloud is swept, the cloud's rotation slows down significantly, and vanishes in a relatively short time. Because the magnetic torques exterted on the cloud do not vanish at that instant, however, the cloud reverses its sense of rotation. This can happen several times (depending on rho/sub cl//rho/sub ext/) before the cloud comes to a complete rest with respect to the surrounding medium. Each reversal of rotation sends out a new wave. A steepening of field lines takes place, raising the possibility of magnetic reconnection in the intercloud medium. For cloud densities < or =10/sup 4/ cm/sup -3/, cosmic rays of energy up to a few times 10/sup 11/ eV may be produced in situ in the neighborhoods of clouds. « less
Prospects of leptoquark discovery with ATLAS at the LHC

Final states with high-pT leptons and jets are predicted by many Beyond the StandardModel (BSM) scenarios including leptoquarks, Left-Right Symmetry, various implementationsof Grand Unification Theory (GUT), and other models. Such theoretical models extendthe application of Quantum Field Theory to energies far above the Electroweak SymmetryBreaking (EWSB) energy scale and seek to provide a much more elegant and symmetricdescription of the fundamental forces. The implications of such models include possible answersto the origins of flavor, CP violation, baryogenesis, and other fundamental questionsbeyond EWSB.This dissertation describes the study of leptoquarks in dielectron-jets final states inproton-proton collisions at a center of mass energy of 14 TeV using ATLAS apparatus at theLarge Hadron Collider at CERN. The presented analysis is based on fully-simulated datasamples that contain two or more high-pT electron candidates and jets for an integratedluminosity of 100 / pb . Signal event selection, analysis algorithms, and suppression of SMbackgrounds are discussed. ATLAS can discover leptoquarks up to masses of 565 GeV at100 / pb for a branching ratio = 1 at a 5 sigma significance level.