Arbitrary Separation Research Articles

O ESPAÇO, O TEMPO E A (DES)CONSTRUÇÃO DE UMA REALIDADE INTEGRADA

Geography has assisted the dialogue between man and the world since classical antiquity. Investigationsfocusing on relationships that take place between unity and diversity, as revealed by the world, are amongthe classical subjects of this knowledge transformed into modern science. Modern science was accomplishedby the ability of the bourgeois revolutions in ensuring the triumph of human reason against myths and beliefsthat, for centuries, condemned man to a condition of servitude. To this end, there was a series of scientificimprovements to meet the demands of a bourgeoisie in need of knowledge, essential to the domination of natureas well as to its transformation into commodities. In this process of adaptation of reality to the demands ofproduction, time and environment were decanted and classified according to virtues and faults attributed tothem previously. The environment was classified as an immobilizer of social dynamics. This category ofanalysis has been linked to studies which are prone to linear perspectives, as time took on a mediating conceptualrole in which the contradiction was present. To break this mistaken perspective, the environment isbeing reinserted into critical social theories in order to overcome the reductionism of such arbitrary separation.

Temperature effects on platinum single-crystal electrodes

This work reviews three different approaches for the study of temperature effects on the platinum single-crystal | solution interphase. First, the method of analysis of temperature-dependent voltammetric data with the help of a generalized isotherm is described and illustrated for the case of adsorbed hydrogen and OH species on Pt(111) in 0.1 M HClO4. This method of analysis allows a detailed evaluation of the thermodynamic data of charge-transfer adsorbed species, namely, the standard molar Gibbs energy, enthalpy and entropy of adsorption and the magnitude of the lateral interaction between adsorbed species. However, a number of assumptions are involved in the application of a generalized isotherm, namely, the assumption of a Langmuirian configurational term and an arbitrary separation of capacitive and faradaic processes. The second approach described here overcomes these assumptions, since it employs Gibbs thermodynamic equations for interphaces to describe temperature effects on electrosorption processes including those in which charge-transfer is allowed. This approach allows evaluation of the entropy of formation of the interphase, being defined as the difference in entropy of the components of the interphase when they are forming it and when they are in the bulk phases. This method of analysis is illustrated through the evaluation of the entropy of formation of the interphase for Pt(111) in 0.1 M HClO4. Finally, it is shown that temperature effects on interfacial processes can also be studied by means of the application of a fast temperature perturbation. This approach opens the possibility to separate the effect of temperature on the different components of the interphase. The fast temperature perturbation is usually achieved with short laser pulses, and hence the method is called the laser-induced temperature jump method. This approach is illustrated here for the case of Pt(111) in 1 mM HClO4 + 0.1 M KClO4, and it is shown that the corresponding laser-induced transients provide direct evidence on the reorientation of the interfacial water network.

ECJ Decides on the Arbitrary Separation of Uniform Service Contracts without Conducting a Europe-Wide Invitation to Tender

ECJ Decides on the Arbitrary Separation of Uniform Service Contracts without Conducting a Europe-Wide Invitation to Tender

Fluctuation-Induced Forces Between Inclusions in a Fluid Membrane Under Tension

We develop an exact method to calculate thermal Casimir forces between inclusions of arbitrary shapes and separation, embedded in a fluid membrane whose fluctuations are governed by the combined action of surface tension, bending modulus, and Gaussian rigidity. Each object's shape and mechanical properties enter only through a characteristic matrix, a static analog of the scattering matrix. We calculate the Casimir interaction between two elastic disks embedded in a membrane. In particular, we find that at short separations the interaction is strong and independent of surface tension.

Interaction of bodies in free surface with consideration of cross-flow

This paper examines the side-force and induced drag on two thin bodies in arbitrary separation, stagger, and Froude number. The cross-flow induced by the interaction between two bodies is addressed by placing a doublet sheet on the body center-plane and the wake. The coupled integral equations for the doublet strength are then solved, subjected to the body boundary conditions and Kutta condition at the trailing edges. The doublet strength is affected by camber of body surface, yawed angle, and the thickness of neighboring body. It has been shown in this paper that the cross-flow induced by the thickness of neighboring body is negligible, compared with yaw angle effect. For a pair of bodies with a small separation and zero stagger, the side-force experienced by each body can be thirty percent larger than that without interaction at certain Froude numbers. However, the total side-force on the two-body system only has a few percent variation and is not sensitive to the separation due to force cancelation. For two bodies with non-zero staggers, the total side-force and induced drag referring to their zero-stagger values are antisymmetric with respect to the stagger. At high Froude numbers, the two bodies interact strongly at large staggers, while at lower Froude numbers, strong interaction occurs at small staggers. The total drag experienced by the two-body system is dominated by the wave drag at medium Froude numbers, and by side-force induced drag at high Froude numbers.

The non-sense of raising school attendance

For over 10 years, the English government has provided extensive funding for initiatives to raise school attendance, especially in the secondary school years, with unclear evidence of success. This paper will discuss some of the difficulties and contradictions associated with the notion of ‘raising school attendance’ and question whether it is a feasible aim. Main points will be as follows: (a) the importance of raising school attendance is based on the correlations found between poor attendance and both low academic achievement and onset of antisocial behaviour. However, the research demonstrates that these associations are not straightforward; (b) the arbitrary separation of pupils with attendance difficulties from those with behavioural/conduct problems ignores knowledge gained in the twentieth century about the causes of social, emotional and behavioural difficulties, including poor attendance and recommended multimodal/multiagency interventions for such problems; and (c) legal sanctions for parents whose children do not attend school remain a threat frequently used by local authorities. There is no evidence that legal sanctions improve attendance when they are applied, yet practitioners continue to use them and may be encouraged to do so. The paper will argue that poor school attendance rate is only a quantifiable measure of a young person's complex difficulties and cannot be improved by simple unsubstantiated solutions. It will question whether the legislation on school attendance difficulties can be justified in view of what is known from empirical research about the causes and development of human behaviour and whether legal sanctions should be imposed on parents for this so-called offence in the twenty-first century.

Analysis of electric field screening by the proximity of two knife-edge field emitters

The electric field of two semi-infinitely wide knife-edge cathodes with arbitrary separation is calculated by using a Schwarz–Christoffel transformation. This geometry could also represent a trench (or scratch) on a flat surface. It is found that the magnitude of the electric field on the knife-edge cathodes depends strongly on the ratio h/a, where h is the height of the knife-edge cathodes and 2a is the distance between the cathodes. When h/a increases, the magnitude of the electric field on the cathode’s surface decreases. This shows the screening of one cathode by another cathode; for example, keeping the height fixed and decreasing the distance between the cathodes, the field enhancement on the corner decreases. Analytic approximations for the divergent electric field in the immediate vicinity of the sharp edge are derived for the cases where h/a>>1, and h/a≪1. These results lead to insight on the relationship of the density of field emitter in field emitting arrays and field emission from rough surfaces.

Polarizability of two conducting spheres

Abstract Exact series expressions are obtained for the longitudinal and transverse polarizabilities of a system of two conducting spheres, for arbitrary sphere radii and separation. In the important case of close approach, where the exact series converge slowly, approximate analytical expressions are obtained. These analytical expressions become more accurate as the distance between the spheres gets small compared to the sphere radii, and reduce to the known analytic values at sphere contact.

An augmented cohesive zone element for arbitrary crack coalescence and bifurcation in heterogeneous materials

AbstractWe demonstrate that traditional cohesive zone (CZ) elements cannot be accurate when used in conjunction with solid elements with arbitrary intra‐element cracking capability, because they cannot capture the load transfer between cohesive interfaces and the solid elements when crack bifurcation or coalescence occurs. An augmented cohesive zone (ACZ) element based on the augmented finite element method formulation is therefore proposed. The new element allows for arbitrary separation of the cohesive element in accordance with the crack configuration of the abutting solid elements, thus correctly maintaining the non‐linear coupling between merging or bifurcating cracks. Numerical accuracy and effectiveness of the proposed ACZ element are demonstrated through several examples. Copyright © 2011 John Wiley & Sons, Ltd.

Electrostatic interaction between two spherical soft particles at small separations

An approximate analytic expression is given for the potential energy of the electrostatic interaction between two identical spherical soft particles (ion-penetrable porous spheres) in a symmetrical electrolyte solution with the help of Derjaguin's approximation. This method uses accurate analytic expressions for the corresponding interaction energy between two parallel similar soft plates (ion-penetrable membranes) obtained previously (J. Colloid Interface Sci., 350 (2010) 249). Agreement with numerical data (J. Colloid Interface Sci., 36 (1989) 523) is excellent for arbitrary potentials and small particle separations, where the Debye–Hückel linearization approximation and the linear superposition approximation are not allowed.

Casimir potential of a compact object enclosed by a spherical cavity

We study the electromagnetic Casimir interaction of a compact object contained inside a closed cavity of another compact object. We express the interaction energy in terms of the objects' scattering matrices and translation matrices that relate the coordinate systems appropriate to each object. When the enclosing object is an otherwise empty metallic spherical shell, much larger than the internal object, and the two are sufficiently separated, the Casimir force can be expressed in terms of the static electric and magnetic multipole polarizabilities of the internal object, which is analogous to the Casimir-Polder result. Although it is not a simple power law, the dependence of the force on the separation of the object from the containing sphere is a universal function of its displacement from the center of the sphere, independent of other details of the object's electromagnetic response. Furthermore, we compute the exact Casimir force between two metallic spheres contained one inside the other at arbitrary separations. Finally, we combine our results with earlier work on the Casimir force between two spheres to obtain data on the leading order correction to the Proximity Force Approximation for two metallic spheres both outside and within one another.

The relativistic operator of interaction of two quasimolecular electrons as a third-order effect of quantum electrodynamics

We solve the problem of interaction two quasimolecular electrons located at an arbitrary separation near different atoms (nuclei). We consider third-order effects in quantum electrodynamics, which include the virtual photon exchange between electrons with emission (absorption) of a real photon. We obtain the general expression for matrix elements of the operator of the effective interaction energy of two quasimolecular electrons with the external radiation field, which allows calculating probabilities of inelastic processes with rearrangement at slow collisions of multicharge ions with relativistic atoms. We demonstrate that consistently taking the natural condition of the interaction symmetry with respect to the two electrons into account results in the appearance of additional terms in the operators of spin-orbit, spin-spin, and retarded interactions compared with the previously obtained expressions for these operators. We construct the operator of the dipole-dipole interaction of two neutral atoms located at an arbitrary separation.

Efficient calculation of Coulomb matrix elements for bilayers of confined charge carriers with arbitrary spatial separation

We describe a practical procedure to calculate the Coulomb matrix elements of 2D spatially separated and confined charge carriers, which are needed for detailed theoretical descriptions of important condensed matter finite systems. We derive an analytical expression, for arbitrary separations, in terms of a single infinite series and apply a u-type Levin transform in order to accelerate the resulting infinite series. This procedure has proven to be efficient and accurate. Direct consequences concerning the functional dependence of the matrix elements on the separation distance, transition amplitudes and the diagonalization of a single electron–hole pair in vertically stacked parabolic quantum dots are presented.

Stability and dynamics of two-soliton molecules

The problem of soliton-soliton force is revisited. From the exact two-soliton solution of a nonautonomous Gross-Pitaevskii equation, we derive a generalized formula for the mutual force between two solitons. The force is given for arbitrary soliton amplitude difference, relative speed, phase, and separation. The latter allows for the investigation of soliton molecule formation, dynamics, and stability. We reveal the role of the time-dependent relative phase between the solitons in binding them in a soliton molecule. We derive its equilibrium bond length, spring constant, frequency, effective mass, and binding energy of the molecule. We investigate the molecule's stability against perturbations such as reflection from surfaces, scattering by barriers, and collisions with other solitons.

Optical Arbitrary Waveform Generation-Based Packet Generation and All-Optical Separation for Optical-Label Switching

This letter introduces a versatile modulation-format transparent optical-label switching (OLS) transmitter based on optical arbitrary waveform generation (OAWG) and all-optical label extraction. The transmitter creates OLS packets, each with a payload and a label generated by OAWG. With the use of a circulator and a fiber Bragg grating (FBG), the payload and label are simultaneously extracted from the packet. Generation and separation of a repeated 100-ps packet with a 10-bit 100-Gb/s payload and a 4-bit 40-Gb/s label in nonreturn-to-zero and return-to-zero on-off keying formats indicate the potential for future OLS packet switching networks using an OAWG-based transmitter and an FBG to remove and add labels. Retrieved spectral and temporal waveform of both the payloads and labels show clearly spectral separation and temporal overlap.

Generation and control of ultrafast pulse trains for quasi-phase-matching high-harmonic generation

Two techniques are demonstrated to produce ultrashort pulse trains capable of quasi-phase-matching high-harmonic generation. The first technique makes use of an array of birefringent crystals and is shown to generate high-contrast pulse trains with constant pulse spacing. The second technique employs a grating-pair stretcher, a multiple-order wave plate, and a linear polarizer. Trains of up to 100 pulses are demonstrated with this technique, with almost constant inter-pulse separation. It is shown that arbitrary pulse separation can be achieved by introducing the appropriate dispersion. This principle is demonstrated by using an acousto-optic programmable dispersive filter to introduce third- and fourth-order dispersions leading to a linear and quadratic variation of the separation of pulses through the train. Chirped-pulse trains of this type may be used to quasi-phase-match high-harmonic generation in situations where the coherence length varies through the medium.

Long range two-particle rapidity correlations in [formula omitted] collisions from high energy QCD evolution

Long range rapidity correlations in A + A collisions are sensitive to strong color field dynamics at early times after the collision. These can be computed in a factorization formalism (Gelis, Lappi and Venugopalan (2009) [1]) which expresses the n-gluon inclusive spectrum at arbitrary rapidity separations in terms of the multi-parton correlations in the nuclear wavefunctions. This formalism includes all radiative and rescattering contributions, to leading accuracy in α s Δ Y , where Δ Y is the rapidity separation between either one of the measured gluons and a projectile, or between the measured gluons themselves. In this paper, we use a mean field approximation for the evolution of the nuclear wavefunctions to obtain a compact result for inclusive two gluon correlations in terms of the unintegrated gluon distributions in the nuclear projectiles. The unintegrated gluon distributions satisfy the Balitsky–Kovchegov equation, which we solve with running coupling and with initial conditions constrained by existing data on electron–nucleus collisions. Our results are valid for arbitrary rapidity separations between measured gluons having transverse momenta p ⊥ , q ⊥ ≳ Q s , where Q s is the saturation scale in the nuclear wavefunctions. We compare our results to data on long range rapidity correlations observed in the near-side ridge at RHIC and make predictions for similar long range rapidity correlations at the LHC.

Extraction of the point-spread function in electron-beam lithography using a cross geometry

For high-quality dose corrections an accurate knowledge of the dose distribution of a single spot, the point-spread function (psf), is required. Usually this information is obtained by writing a set of parallel lines of variable separation and dosage. Subsequent analysis gives information about the value of the psf as a function of the chosen separation. Here we present an alternative method to extract the psf at arbitrary separation and to a high degree of accuracy. This is based upon the exposure of a cross shaped geometry, in which all relevant separations are present.

Dispersive interactions between atoms and nonplanar surfaces

We calculate the dispersive force between a ground state atom and a non planar surface. We present explicit results for a corrugated surface, derived from the scattering approach at first order in the corrugation amplitude. A variety of analytical results are derived in different limiting cases, including the van der Waals and Casimir-Polder regimes. We compute numerically the exact first-order dispersive potential for arbitrary separation distances and corrugation wavelengths, for a Rubidium atom on top of a silicon or gold corrugated surface. We discuss in detail the inadequacy of the proximity force approximation, and present a simple but adequate approximation for computing the potential.

Pharmaceutical reforms: Implications through comparisons of Korea and Japan

This paper compares the process and results of the reform which confined doctors to prescribing and pharmacists to dispensing in both Korea and Japan from comparative and politico-economic perspectives. At the present time, several years since the reforms were implemented, a 'compulsory separation' is being established in Korea. The claims containing antibiotics against the total claims from the doctor's clinic dropped from 55.7% in 2000 to 29.6%, and the number of drugs per claim from 5.9 in 2000 to 4.2 in 2008. Japan selected an 'arbitrary separation'. Efforts to raise the rate of the 'separation' have increased the rate from 1% in 1974 to 57.2% in 2007, but nearly half of medical prescriptions are still being dispensed by doctors. Disparity in the two countries has been brought about by what follows: first, the president's political leadership caused a radical shift in the attitude of the bureaucratic group in Korea; second, in their confrontation with doctors the pharmacists' camp in Korea proved to hold political power stronger than that in Japan; third, intervention in policy of progressive civic groups in particular played a pivotal role in accomplishing the reform in Korea.