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Especially in the field of automotive applications smart sensor systems for magnetic field sensing face increasing requirements concerning low cost, low power consumption and high magnetic performance. Over the past years AMR sensors play a decisive role in this application area because of their robustness and stability. In the following a high-integrated smart sensor system for magnetic field sensing is presented. A novel approach for the detection of weak magnetic fields is shown, which is based on an AC-excitation of AMR elements. In contrast to common used sensors this concept is based on a nonlinear AMR element without Barber pole construction. By means of this methodology sensitivity as well as temperature and life time stability is significantly improved, while the production costs compared to common-used sensors are reduced. Within this novel approach new signal conditioning algorithms and analog circuit topologies are presented, which are able to meet low offset and low noise requirements.

To obtain information about the mechanism of high Tc superconductivity in YBa2Cu3O7-δ (YBCO) the dependence of Hall coefficient RH and electrical resistivity ρ on the temperature were studied in range from 77 to 300K. An inflexion point θ was found to exist around 130K in RH(T) and ρ(T) curves. Both the mobility μ and the concentration of the holes were evaluated above and below θ, separately. The μ of the holes dominant below θ was ten times greater than that above θ. The concentration of the heavy holes above θ was, however, one hundred times larger than that below θ. A discussion will be given in terms of the transport process of the holes drifting through P[sgrave]- and Pσ-orbits on the CuO2 planes in YBCO.

In this paper, we show that the non-Newtonian gravitational potential can be explained by a scalar-tensor model with torsion in the weak field and static state approximation. The torsional effect is the intermediate-range interaction.

Model equations for the kinetics of the synthesis and decay of molecular aggregates are used to show the high sensitivity of equilibrium concentrations of high-molecular aggregates to external radiation. This phenomenon is used to explain the effects of low-intensity microwave fields on the functioning of biological systems. The experimental results on the influence of SHF-radiation on ferricyanide reduction by erythrocytes are interpreted in detail.

Recent experimental studies on quantum wires subjected to a doubly-corrugated gate displayed periodic oscillations in the weak field magneto-resistance [1]. The presence of peaks in the magneto-resistance were associated with specific ballistic backscattered trajectories that were highly sample (and thus geometry) dependent. In this paper we describe simulations of such structures.

International audience; We theoretically demonstrate the coherent control of the effective susceptibility of a duplicated two-level system. The control is obtained for a linearly polarized weak field in the presence of a much stronger orthogonally polarized field. For small optical depths, the effective susceptibility chi(eff) behaves as chi(lin)e(2i phi) (chi(lin) is the linear susceptibility, phi the phase shift) allowing coherent control of the optical response. For large optical depths, chi(eff)approximate to chi(*)(lin), turning an absorber into an amplifier without affecting the dispersion.

PurposeThis paper aims to propose a high‐frequency (HF) model able to compute the flux density in the vicinity of the laminated stator core of an AC machine.Design/methodology/approachExperiments form the main approach. Analytical results previously obtained with a simplified rectangular laminated structure are confirmed with a standard cylindrical magnetic core.FindingsThree frequency domains are defined, depending on the skin depth relative to the thickness of the magnetic sheets. A methodological approach is proposed for each domain. For higher frequencies, the magnetic core can be considered as transparent for external field computation.Research limitations/implicationsThe HF model is valid for skin depths much lower than the thickness of the magnetic sheets.Practical implicationsThe proposed HF model provides a link between the weak field measured in the natural void existing between the stator core and the housing of large electrical machines. With such a link, it is possible to develop a new monitoring system able to detect and to localize the partial discharges in the stator winding of a large machine.Originality/valueThe low‐frequency limit of the model has been measured. It corresponds to a ratio of 1/40 between the skin depth and the magnetic sheet thickness. Therefore this model offers a new perspective for maintenance applications.

We develop an analytical approach on electromagnetically induced transparency (EIT) in a Doppler broadened medium consisting of five-level cascade systems excited by a strong coupling and weak probe laser fields. In a weak field limit of the probe light, EIT spectrum is interpreted as functions of controllable parameters of the coupling light and temperature of the medium. The theoretical interpretation of EIT spectrum is applied to the case of 85Rb atoms and compared with available experimental observation. Such an analytical interpretation provides quantitative parameters to control properties of the Doppler broadened EIT medium, and it is useful to find related applications.

The switching of polarization in ferroelectrics is considered as the first-order phase transition. By the analogy with the theory of crystal growth it is assumed that the switching process is determined by the oversaturation degree which correspond in ferroelectrics to the magnitude of electric field on the domain boundary. It is supposed that the mechanism of domain wall motion in strong field is due to the twodimensional nucleation and in weak field is due to the one-dimensional nucleation. The criterion of strong field IS defined. From this point of view it have been explained the peculiarities of domain structure dynamics in two uniaxial ferroelectrics: lead germanate and gadolinium molybdate.

A simple and convenient method is proposed for determining the configuration of E,Z-isomers of 2-, 3-, and 4-benzoylpyridines. The difference in chemical shifts (δδ, ppm) in the system CCl4-DMSO-D6 and CCl4-DMSO-CF3COOD for the α-H atoms or the α, Β-C atoms of the pyridine ring can be used to determine the configuration. The shift (δδ) of the α-H signals to weak field is greater for the Z-isomers than for the E-isomers due to protonation of the pyridine nitrogen atom. The reverse dependence is seen in the 13C NMR for the E,Z-isomers. The signals of the α-C atoms shift to stronger field after protonation.

A general form of the gain formula for the Compton-type free-electron laser with electromagnetic fields of any polarization and field strength is presented. In the case of circularly polarized fields, the result is reduced to the Chan-Tsui formula and can also be further reduced to the Colson formula by means of the first order “weak field” approximation.

In this paper, a self-learning support system for pupils in an elementary course is proposed. In making of homework for self-learning, by using a fuzzy scheme, the proposed system assists the choice of questions which are suitable for the level of scholastic ability. Furthermore, by presuming the weak field and the degree of the improved ability of each pupil, the proposed fuzzy-based system adjusts the level of the question for the homework. As one of the simplest examples, the proposed system for arithmetic training is realized by using a visual basic. The validity of the proposed system is confirmed through experiments. The experiments show that the proposed system can provide appropriate questions depending on the ability level of pupil.

Modified gravity theory is known to violate Birkhoff's theorem. We explore a key consequence of this violation, the effect of distant matter in the Universe on the motion of test particles. We find that when a particle is accelerated, a force is experienced that is proportional to the particle's mass and acceleration and acts in the direction opposite to that of the acceleration. We identify this force with inertia. At very low accelerations, our inertial law deviates slightly from that of Newton, yielding a testable prediction that may be verified with relatively simple experiments. Our conclusions apply to all gravity theories that reduce to a Yukawa-like force in the weak field approximation., Comment: 4 pages, 3 figures; published version with updated references

We report observation of spin-orbit Berry's phase in the Aharonov-Bohm (AB) type oscillation of weak field magnetoresistance in an anti-dot lattice (ADL) of a two-dimensional hole system. An AB-type oscillation is superposed on the commensurability peak, and the main peak in the Fourier transform is clearly split up due to variation in Berry's phase originating from the spin-orbit interaction. A simulation considering Berry's phase and the phase arising from the spin-orbit shift in the momentum space shows qualitative agreement with the experiment., Comment: 13 pages, 5 figures

We numerically investigate gauge field instabilities in anisotropic SU(2) plasmas using weak field initial conditions. The growth of unstable modes is stopped by non-abelian effects for moderate anisotropy. If we increase the anisotropy the growth continues beyond the non-abelian saturation bound. We find strong indications that the continued growth is not due to over-saturation of infrared field modes, but instead due to very rapid growth of high momentum modes which are not unstable in the weak field limit. The saturation amplitude strongly depends on the initial conditions. For strong initial fields we do not observe the sustained growth., Comment: 28 pages, 17 figures

Spherical symmetry in $f(R)$ gravity is discussed in details considering also the relations with the weak field limit. Exact solutions are obtained for constant Ricci curvature scalar and for Ricci scalar depending on the radial coordinate. In particular, we discuss how to obtain results which can be consistently compared with General Relativity giving the well known post-Newtonian and post-Minkowskian limits. Furthermore, we implement a perturbation approach to obtain solutions up to the first order starting from spherically symmetric backgrounds. Exact solutions are given for several classes of $f(R)$ theories in both $R =$ constant and $R = R(r)$., Comment: 13 pages

We demonstrate the measurement of field-free molecular alignment of air can be realized by combining the weak field polarization technique (WFPT) with a balanced detection system. The measured signal is proportional to the alignment parameter. Periodic revival structures of the transient alignment and permanent alignment between revivals can be detected clearly by a single measurement with high sensitivity. Fourier transform spectrum of the measured signal agrees well with the calculation result and provides information of the populations of different J states in the rotational wave packet.

Parametrized post-Newtonian formalism is one of the standard methods of experimental check of gravity theories and limiting the model parameters. In this work we consider the PPN-paramertization of Randall-Sundrum II black hole solutions and show that these solutions are in good agreement with the GR predictions and the observation results.

The localization properties of the single-particle and collective electron excitations were investigated in the intentionally disordered GaAs/AlGaAs superlattices by weak field magnetoresistance and Raman scattering. The localization length of the individual electron was found to be considerably larger than that one of the collective excitations. This suggests that the disorder has weaker effect on the electrons than on their collective motion and that the interaction which gives rise to the collective effects increases localization.

We discuss the contribution to the characteristic lensing quantities, i.e., the deflection angle and Einstein radius, due to the higher-order terms (e.g., the gravitomagnetic terms) considered in the lens potential. The cases we analyze are the singular isothermal sphere and the disk of spiral galaxies. It is possible to see that the perturbative effects could be of the order 10 −3 with respect to the ordinary terms of weak field and thin lens approximations, so that it is not a far hypothesis to obtain evidences of them in a next future by suitable experiments.

We investigate in detail two physical properties of the metric f(R) theory developed by Sobouti (2007). We first look for the possibility of producing gravitational waves that travel at the speed of light. We then check the possibility of producing extra bending in the lenses produced by the theory. We do this by using standard weak field approximations to the gravitational field equations that appear in Sobouti's theory. We show in this article that the metric theory of gravitation proposed by Sobouti (2007) predicts the existence of gravitational waves travelling at the speed of light in vacuum. In fact, this is proved in general terms for all metric theories of gravity which can be expressed as powers of Ricci's scalar. We also show that an extra additional lensing as compared to the one predicted by standard general relativity is produced. These two points are generally considered to be of crucial importance in the development of relativistic theories of gravity that could provide an alternative description to the dark matter paradigm., Comment: 10 pages, 2 figures. Added a comment on the recent article by Saffari (arXiv:0704.3345v1) and small typos as well as general comments in the introuduction and conclusion

We study spherically symmetric solutions in f(R) theories and its compatibility with local tests of gravity. We start by clarifying the range of validity of the weak field expansion and show that for many models proposed to address the Dark Energy problem this expansion breaks down in realistic situations. This invalidates the conclusions of several papers that make inappropriate use of this expansion. For the stable models that modify gravity only at small curvatures we find that when the asymptotic background curvature is large we approximately recover the solutions of Einstein gravity through the so-called Chameleon mechanism, as a result of the non-linear dynamics of the extra scalar degree of freedom contained in the metric. In these models one would observe a transition from Einstein to scalar-tensor gravity as the Universe expands and the background curvature diminishes. Assuming an adiabatic evolution we estimate the redshift at which this transition would take place for a source with given mass and radius. We also show that models of dynamical Dark Energy claimed to be compatible with tests of gravity because the mass of the scalar is large in vacuum (e.g. those that also include R^2 corrections in the action), are not viable., Comment: 26 pages

The recently constructed magnetochemical series for weak field anionic ligands, based on a sensitive ranking of the degree of admixture in S = 3 2 , 5 2 spin state complexes of the type FeX(porphyrin) and FeX(phthalocyanin), can be extended to stronger field ligands X− by considering zero field splitting and spin crossover information available in the iron porphyrin literature. This leads to the ligand field strength ordering

Stark deceleration is one of the few methods that can be used to slow polyatomic molecules. We present calculations of Stark shift energies, a quantitative analysis of nonadiabatic transition probabilities, and orientational distribution functions applicable to typical Stark slowing conditions for the two small asymmetric rotors nitromethane and acetaldehyde. We show that asymmetric polyatomic molecules are good candidates for Stark slowing.

(eV)”. The PDG value isan adjustment of theoretical predictions to fit physical observation. The derivation presented herein iswithout adjustment and may represent physical evidence of the existence of Euler’s Constant in natureat the quantum level.1 INTRODUCTIONIt shall be demonstrated that the Polarizable Vacuum (PV) model of gravitation, [1]complimenting General Relativity (GR) in the weak field, is capable of predicting the Photon mass-energy threshold to within 4.3(%) of the PDG endorsed prediction presented by Eidelman et. al . in [2]of “< 6 x 10

Gravitational lensing by a spinning deflector in translational motion relative to the observer is discussed in the weak field, slow motion approximation. The effect of rotation, which generates an intrinsic gravito-magnetic field, separates from that due to radial motion. Corrections to the lens equation, deflection angle and time delay are derived., 4 pages; this is a preprint of an article accepted for publication in MNRAS

We reconsider the unified model of gravitation and Yang--Mills interactions proposed by Chakraborty and Peld\'an, in the light of recent formal developments in loop quantum gravity. In particular, we show that one can promote the Hamiltonian constraint of the unified model to a well defined anomaly-free quantum operator using the techniques introduced by Thiemann, at least for the Euclidean theory. The Lorentzian version of the model can be consistently constructed, but at the moment appears to yield a correct weak field theory only under restrictive assumptions, and its quantization appears problematic., Comment: 4 pages, dedicated to Michael P. Ryan on the occasion of his sixtieth birthday

The Weyl gravity appears to be a very peculiar theory. The contribution of the Weyl linear parameter to the effective geodesic potential is opposite for massive and nonmassive geodesics. However, photon geodesics do not depend on the unknown conformal factor, unlike massive geodesics. Hence light deflection offers an interesting test of the Weyl theory. In order to investigate light deflection in the setting of Weyl gravity, we first distinguish between a weak field and a strong field approximation. Indeed, the Weyl gravity does not turn off asymptotically and becomes even stronger at larger distances. We then take full advantage of the conformal invariance of the photon effective potential to provide the key radial distances in Weyl gravity. According to those, we analyze the weak and strong field regime for light deflection. We further show some amazing features of the Weyl theory in the strong regime., Comment: 20 pages, 9 figures (see published version for a better resolution, or online version at stacks.iop.org/CQG/21/1897)

It is well known that a strongly driven transition exhibits a doublet splitting when probed by a weak field, commonly known as AC Stark splitting. It can be observed either by probing the driven two-level itself (Mollow-type spectrum) or via a third level (Autler-Townes-type spectrum). These two type splittings can have very different characteristics, particularly when driven resonantly. The absorptive Mollow spectrum consists of two dispersion-like features, whereas for the Autler-Townes spectrum there is a simple doublet splitting. In this paper we report the observation of both Mollow and Autler-Townes spectrum simultaneously by applying two strong driving fields in a three-level configuration.

We study the stability properties of the Kidder-Scheel-Teukolsky (KST) many-parameter formulation of Einstein's equations for weak gravitational waves on flat space-time from a continuum and numerical point of view. At the continuum, performing a linearized analysis of the equations around flat spacetime, it turns out that they have, essentially, no non-principal terms. As a consequence, in the weak field limit the stability properties of this formulation depend only on the level of hyperbolicity of the system. At the discrete level we present some simple one-dimensional simulations using the KST family. The goal is to analyze the type of instabilities that appear as one changes parameter values in the formulation. Lessons learnt in this analysis can be applied in other formulations with similar properties., 17 Pages, RevTex, 16 figures

It was recently observed [van der Beek et al., Phys. Rev. B 54, R792 (1996)] that irradiated layered high-T c superconductors subject to perpendicular magnetic field manifest two similar scaling behaviors corresponding totwo different critical temperatures. We show that this phenomenon is explained within the framework of the Ginzburg-Landau theory, In the weak field region, the scaling function differs from that of a clean sample mainly because of the renormalization of the critical temperature, due to defects. In the strong field region, defects are effectively suppressed and the scaling function, as well as the critical temperature, are the same as in a clean superconductor. The theory presented here agrees quite satisfactory with experiment.

We have devoted an effort to study some nonlinear actions, characteristics of the ${\cal W}$-theories, in the framework of the soldering formalism. We have disclosed interesting new results concerning the embedding of the original chiral ${\cal W}$-particles in different metrical spaces in the final soldered action, i.e., the metric gets modified by the soldering interference process. The results are presented in a weak field approximation for the ${\cal W}_N$ case when N is greater than 3 and also in an exact way for ${\cal W}_2$. We have promoted a generalization of the interference phenomena to ${\cal W}_N$-theories of different chiralities and shown that the geometrical features introduced can yield a new understanding about the interference formalism in quantum field theories., 28 pages, Latex

In my abstract (Runcorn, l993) I have summarized the impact that palaeomagnetism has had on studies of the Earth and the Moon and may be expected to have on Mars, when rocks are returned from this planet and detailed satellite magnetometer surveys are made from moderate heights above its surface. It is surely one of the most remarkable discoveries of science that such a weak field as that of the Earth or early Moon is faithfully recorded in rocks, though today geophysicists accept it as commonplace. It is equally remarkable that palaeomagnetism turned out to be the key technique for settling such fundamental questions of geodynamics as continental drift and sea floor spreading and the constitution and early dynamics of the Moon. Further developments in palaeomagnetism are difficult to predict but in my abstract I have produced a list of priorities with which I expect most palaeomagnetists would agree.

Auxiliary Shock Improves Defibrillation.Introduction: This study tested the hypothesis that the defibrillation threshold (DFT) can be lowered by delivering a weak auxiliary shock in conjunction with a stronger primary shock to the cardiac region where the primary shock electric field is weakest. Methods and Results: Eight swine were studied in each of two study parts. In both parts, DFTs were determined for dual shocks delivered through two electrode pairs. The biphasic primary shock was delivered through electrodes in the right ventricle and superior vena cava. The auxiliary shock was delivered through a separate electrode in the superior vena cava and a left ventricular electrode placed where the primary shock field was presumed to be weakest. In part I, a monophasic auxiliary shock of 50, 100, or 150 V was delivered either simultaneously with or 1, 20, or 40 msec before primary shock. When auxiliary shock was delivered simultaneously with or 1 msec before primary shock, DFT energy was reduced by approximately 50% compared with primary shock alone. In part II, a 150-V monophasic or biphasic auxiliary shock of either polarity was delivered 1 msec before or after primary shock. Regardless of waveform or polarity, all auxiliary shock delivered before primary shock lowered DFT energy by approximately 30% compared with primary shock alone. Depending on waveform and polarity, auxiliary shock delivered after primary shock either did not significantly change the DFT or elevated the DFT compared with primary shock alone. Conclusion: Application of a small auxiliary shock, just before or simultaneously with a primary shock, to the cardiac region where the primary shock field is weakest significantly lowers DFT.

We present here a manifestly gauge invariant calculation of vacuum polarization to fermions in the presence of a constant Maxwell and a constant Kalb-Ramond field in four dimensions. The formalism is a generalisation of the one used by Schwinger in his famous paper on gauge invariance and vacuum polarization. We get an explicit expression for the vacuum polarization induced effective Lagrangian for a constant Maxwell field interacting with a constant Kalb-Ramond field. In the weak field limit we get the coupling between the Maxwell field and the Kalb-Ramond field to be $(\tilde{H}.\tilde{F})^2$, where ${\tilde H}_{\mu}= {1\over {3!}}\epsilon_{\mu\alpha\beta\lambda}H^{\alpha\beta\lambda}$ and $\tilde F$ is the dual of $F_{\mu\nu}$., Comment: 16 pages, Revtex

The effects of magnetic field on terahertz radiation emitted from the rectangular mesa of intrinsic Josephson junctions (IJJ’s) made of Bi2212 single crystals were studied up to 150 Oe. Strong suppression of the radiation power was observed when magnetic field was applied to the c -axis of the sample, while in the case of H // ab -plane, the radiation power showed a weak and broad peak in the weak field region (∼50 Oe), then it decreased and diminished around 150 Oe. These magnetic field effects are interpreted by the strong influence of magnetic field on the I – V curve, which set up the condition for the THz radiation.

In this paper, the theoretical model and experimental demonstration of Cs 852nm FADOF in weak and strong magnetic field are discussed. Whenthe FADOF system working under the weak field, the theoretical and experimental results are agreement with the previous repot. In the case of strong field, when performing condition is B equals 0.0883T, T equals 351K, the line-center operation is observed. The comparison between the theory and the experiment gives reasonably expected results.

Herein I examine the vibrational controllability of a molecular system in a weak polarized field. Prerequisite rotational control in a weak field is also considered within the sudden limit. Finally, the effects on molecular controllability of higher order interactions with an intense field are explored

The weak-field expansion of the charged fermion propagator under a uniform magnetic field is studied. Starting from Schwinger's proper-time representation, we express the charged fermion propagator as an infinite series corresponding to different Landau levels. This infinite series is then reorganized according to the powers of the external field strength $B$. For illustration, we apply this expansion to $\gamma\to \nu\bar{\nu}$ and $\nu\to \nu\gamma$ decays, which involve charged fermions in the internal loop. The leading and subleading magnetic-field effects to the above processes are computed., Comment: 17 pages, section IIIB added, some typos corrected

We find general non-linear lagrangians of a U(1) field invariant under electric-magnetic duality. They are characterized by an arbitrary function and go to the Maxwell theory in the weak field limit. We give some explicit examples which are generalizations of the Born-Infeld theory., 15 pages, Latex, minor changes in the introduction, final version to be published in Nuclear Physics B

We investigate the photon statistics of light transmitted from a driven optical cavity containing one or two atoms interacting with a single mode of the cavity field. We treat arbitrary driving fields with emphasis on departure from previous weak field results. In addition effects of dephasing due to atomic transit through the cavity mode are included using two different models. We find that both models show the nonclassical correlations are quite sensitive to dephasing. The effect of multiple atoms on the system dynamics is investigated by placing two atoms in the cavity mode at different positions, therefore having different coupling strengths., Comment: 8 pages, 10 figures, minor typographical errors corrected, submitted to Phys Rev A

Relativistic tunnel ionization of atoms by intense, elliptically polarized light is considered. The relativistic version of the Landau-Dykhne formula is employed. The general analytical expression is obtained for the relativistic photoelectron spectra. The most probable angle of electron emission, the angular distribution near this angle, the position of the maximum and the width of the energy spectrum are calculated. In the weak field limit we obtain the familiar non-relativistic results. For the case of circular polarization our analytical results are in agreement with recent derivations of Krainov [V.P. Krainov, J. Phys. B, {\bf 32}, 1607 (1999)]., Comment: 8 pages, 2 figures, accepted for publication in Journal of Physics B

The Hanle effect is discussed as a means of diagnosing both the strength and geometry of stellar magnetic fields from measurements of resonance line polarization. The effect refers to the modification of resonance line scattering polarization in the presence of a magnetic field. Perhaps the most attractive feature of the Hanle effect is that magnetic sensitivities of typical resonance lines of astrophysical interest lie in the range 1–1000 G, a regime of weak field strengths that may be important for stellar variability, winds, and evolution, but which are generally difficult to detect using standard methods based on the more well-known Zeeman effect.

We consider a Wannier–Stark problem with only one ladder for weak field. We prove that a generic first-band state is a metastable state (Wannier–Bloch oscillator) oscillating because of a beating effect and decaying at the rate given by the imaginary part of the Wannier-Stark resonances. By this result we have at the same time the realization of the ideas of Bloch about the oscillations, of Wannier about the approximate quantization and of Zener about the metastability. Such oscillators, which generically perform a breathing mode motion in a large spatial region, have been experimentally observed.