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The separation characteristics of a planar collector system placed in the weak magnetic field region of a facility that separates isotopes of stable metals by the ion-cyclotron-resonance method are calculated. An increase in the gyroradius of the accelerated ions in the weak field allows the designer to increase the collector plate spacing and decrease undesired screen losses. It is theoretically shown that placing the collector in the week field increases the degree of separation. Also, the transverse-to-longitudinal ion energy conversion makes it possible to extend the product deposition area on the collector plates and, thus, to reduce the thermal load on the collector and facilitate the long-term production of the target material in large amounts.

Recent general-relativistic extensions of Newtonian rotation laws for self-gravitating stationary fluids allow one to rederive, in the first post-Newtonian approximation, the well known geometric dragging of frames, and two new weak-field effects within rotating tori. These are the recently discovered anti-dragging and a new effect that measures the deviation from the Keplerian motion and/or the contribution of the fluids selfgravity. They can be applied to the study of the existence of the (post-)Newtonian limits of solutions and in investigations of inequalities relating parameters of rotating black holes., Comment: A talk presented by Edward Malec at MG14 conference in Rome

Quantum properties of optical modes are typically assessed by observing their photon statistics or the distribution of their quadratures. Both particle- and wave-like behaviours deliver important information, and each may be used as a resource in quantum-enhanced technologies. Weak-field homodyne detection provides a scheme which combines the wave- and particle-like descriptions. Here we show that it is possible to observe a wave-like property such as the optical coherence across Fock basis states in the detection statistics derived from discrete photon counting. We experimentally demonstrate these correlations using two weak-field homodyne detectors on each mode of two classes of two-mode entangled states. Furthermore, we theoretically describe the response of weak-field homodyne detection on a two-mode squeezed state in the context of generalised Bell inequalities. Our work demonstrates the potential of this technique as a tool for hybrid continuous/discrete-variable protocols on a phenomenon that explicitly combines both approaches., Comment: 19 pages, 12 figures (arXiv version) -- Supplementary Figure 7 modified and minor typos fixed

We present a general relativistic version of the self-gravitating fluid model for the dark sector of the Universe (darkon fluid) introduced in Phys. Rev. 80 (2009) 083513 and extended and reviewed in Entropy (2013) 559. This model contains no free parameters in its Lagrangian. The resulting energy-momentum tensor is dustlike with a nontrivial energy-flow. In an approximation valid at sub-Hubble scales we find that the cosmic acceleration is not attributed to any kind of negative pressure but it is due to a dynamically determined sign change of the energy density. This property turns out to be equivalent to a time-dependent, sign changing curvature. The cosmological equations obtained agree with those of the nonrelativistic model but they are given a new physical interpretation. Furthermore we have derived the self-consistent equation to be satisfied by the nonrelativistic gravitational potential produced by a galactic halo in our model from a weak field limit of a generalized Tolman-Oppenheimer-Volkoff equation., Comment: 28 pages to appear in EPJC

The effect of currents of mass on bending of light rays is considered in the weak field regime. Following Fermat's principle and the standard theory of gravitational lensing, we derive the gravitomagnetic correction to time delay function and deflection angle caused by a geometrically-thin lens. The cases of both rotating and shifting deflectors are discussed.

The c-number atomic Bloch equations modelling the coupling of a 2-photon 2-level single atom with a non-resonant ( ) squeezed vacuum (SV) radiation reservoir show that: (i) The quantum interference (QI) process, of parameter , between the 2-photon transition channels causes coupling of the atomic variables (inversion and polarisation), and, (ii) The SV reservoir parameters ( N, M ) induce periodic coefficients and hence inhibited oscillatory behaviour in the atomic variables. Perturbative analytical solutions of these non-autonomous Bloch equations are derived and used to calculate the absorption spectrum of a weak field probing the system. Of particular, the zero-absorption isolines in the relevant ( N, f )- and ( )-planes of the system parameters are identified computationally. It is found that, the largest set of points, where absorption is zero, in the -plane depends on the choice of the degree of squeezing parameter (M) of the SV reservoir.

Electrophoresis of a diffuse soft particle with a charged hydrophobic core is considered under the weak field and low charge density assumptions. The hydrophobic surface of the core is coated with a diffuse polyelectrolyte layer (PEL) in which a gradual transition of the polymer segment distribution from the impenetrable core to the surrounding electrolyte medium is considered. A mathematical model is adopted to analyse the impact of the core hydrophobicity on the diffuse soft particle electrophoresis. The mobility based on the present model for the limiting cases such as bare colloids with hydrophobic core and soft particles with no-slip rigid cores are in good agreement with the existing results. The presence of PEL charges produces the impact of the core hydrophobicity on the soft particle mobility different from the corresponding bare colloid with hydrophobic surface in an electrolyte medium. The impact of the core hydrophobicity is subtle when the hydrodynamic screening length of the PEL is low. Reversal in mobility can be achieved by tuning the core hydrophobicity for an oppositely charged core and PEL.

We define chiral fermions in the presence of non-trivial gravitational and gauge background fields in the framework of locally covariant field theory. This allows to straightforwardly compute the chiral anomalies on non-compact Lorentzian space-times, without recourse to a weak field approximation., Comment: 19 pages

We write down explicit expressions for the $x$-evolution (equivalent to energy or rapidity evolution) of $2 n$ ($n = 1, 2, ...$) Wilson lines using the JIMWLK equation and the Color Glass Condensate formalism. We investigate the equation in the weak gluon field limit (linear regime) by expanding the Wilson lines in powers of the gluon field and show that it reduces to the BJKP equation describing the evolution of a state of $2 n$ Reggeized gluons with energy. We also make available for download a {\it Mathematica} program which provides this expression for any value of $n$.

We measured the transverse magnetoresistivity of the mixed valence compound $\alpha$-YbAlB$_4$. Two configurations were used where current was applied along [110] direction for both and magnetic field was applied along [-110] and $c$-axis. We found the transverse magnetoresistivity is highly anisotropic. In the weak field below 1 T, it is consistent with stronger $c$-$f$ hybridization in the $ab$ plane which was suggested from the previous zero field resistivity measurements. At the higher field above 3 T, we observed a negative transverse magnetoresistivity for the field applied along the $c$-axis. The temperature dependences of the resistivity measured at several different fields suggest the suppression of the heavy fermion behavior at the characteristic field of $\sim 5.5$ T., Comment: 6pages, 4 figures

Low-temperature thermal conductivity measurements were performed on single crystals of $\mathrm{TlNi}{}_{2}\mathrm{Se}{}_{2}$, a nickel chalcogenide heavy-electron superconductor with ${T}_{c}\ensuremath{\simeq}3.7$ K. In zero field, the residual electronic contribution at $T\ensuremath{\rightarrow}0$ K (${\ensuremath{\kappa}}_{0}/T$) was well separated from the total thermal conductivity, which is less than 0.45% of its normal-state value. Such a tiny residual ${\ensuremath{\kappa}}_{0}/T$ is unlikely contributed by the nodal quasiparticles. The nodeless gap structure is supported by the very weak field dependence of ${\ensuremath{\kappa}}_{0}(H)/T$ in low magnetic fields. In the whole field range, ${\ensuremath{\kappa}}_{0}(H)/T$ exhibits an $\mathsf{S}$-shaped curve, as in the case of nickel pnictides $\mathrm{BaNi}{}_{2}\mathrm{As}{}_{2}$ and $\mathrm{SrNi}{}_{2}\mathrm{P}{}_{2}$. This common feature of nickel-based superconductors can be explained by multiple nodeless superconducting gaps.

The paper describes measurement and calculation of 2D distribution of the vibration signal originated by the gradient coil system of the magnetic resonance imaging (MRI) equipment. The measurement experiments were performed at the bottom plastic holder of the scanning area of the open-air weak magnetic field MRI device. Selection of a usable type of a vibration sensor for measurement in a magnetic field with low B0 up to 0.2 T is also discussed. Realized calibration of the chosen sensor (sensitivity and frequency response) together with determination of the propagation time delay between the excitation impulses and the subsequently generated vibration signal is mentioned, too. The picked-up vibration signal exhibits harmonic character so it is suitable to describe it by determined spectral properties and features. Obtained statistical results of spectral analysis will be used to improve image sharpening and reduction of the motion effect in the MR pictures of thin layer samples and phantoms scanned by this MRI system.

We consider population transfer in open quantum systems, which are described by quantum dynamical semigroups (QDS). Using second order perturbation theory of the Lindblad equation, we show that it depends on a weak external field only through the field's autocorrelation function (ACF), which is phase independent. Therefore, for leading order in perturbation, QDS cannot support dependence of the population transfer on the phase properties of weak fields. We examine an example of weak-field phase-dependent population transfer, and show that the phase-dependence comes from the next order in the perturbation., 24 pages, 6 figures

The work reported here was partially supported by an EPSRC postgraduate studentship to L.A.K.B. L.A.K.B. was further supported by an EPSRC doctoral prize. We study inertial-range dynamics and scaling laws in unforced two-dimensional magnetohydrodynamic turbulence in the regime of moderately small and small initial magnetic-to-kinetic energy ratio $r_0$, with an emphasis on the latter. The regime of small $r_0$ corresponds to a relatively weak field and strong magnetic stretching, whereby the turbulence is characterized by an intense conversion of kinetic into magnetic energy (dynamo action in the three-dimensional context). This conversion is an inertial-range phenomenon and, upon becoming quasi-saturated, deposits the converted energy within the inertial range rather than transferring it to the small scales. As a result, the magnetic energy spectrum $E_\b(k)$ in the inertial range can become quite shallow and may not be adequately explained or understood in terms of conventional cascade theories. It is demonstrated by numerical simulations at high Reynolds numbers (and unity magnetic Prandtl number) that the energetics and inertial-range scaling depend strongly on $r_0$. In particular, for fully developed turbulence with $r_0$ in the range $[1/4,1/4096]$, $E_\b(k)$ is found to scale as $k^{\alpha}$, where $\alpha\gtrsim-1$, including $\alpha>0$. The extent of such a shallow spectrum is limited, becoming broader as $r_0$ is decreased. The slope $\alpha$ increases as $r_0$ is decreased, appearing to tend to $+1$ in the limit of small $r_0$. This implies equipartition of magnetic energy among the Fourier modes of the inertial range and the scaling $k^{-1}$ of the magnetic potential variance, whose flux is direct rather than inverse. This behavior of the potential resembles that of a passive scalar. However, unlike a passive scalar whose variance dissipation rate slowly vanishes in the diffusionless limit, the dissipation rate of the magnetic potential variance scales linearly with the diffusivity in that limit. Meanwhile, the kinetic energy spectrum is relatively steep, followed by a much shallower tail due to strong anti-dynamo excitation. This gives rise to a total energy spectrum poorly obeying a power-law scaling. Postprint

Neuropathic pain and major depressive disorder are two disorders that affect a large proportion of the population and that lead to vast losses of well being, productivity and money. Transcranial magnetic stimulation has been applied in both conditions, with encouraging results. Here we describe experimental treatment of these conditions with weak field transcerebral pulsed electromagnetic fields. Experimentel heat pain could be reduced with our stimulation, but this effect did not generalize to the capsaicin pain model in healthy volunteers. Studies in neuropathic pain patients have just finished data acquisition and studies in depressed patients are ongoing. We conclude that this type of weak field transcerebral pulsed electromagnetic stimulation deserves serious consideration in health care.

We demonstrate theoretically that laser-induced coherent quantum interference control of asymptotic states of dissociating molecules is possible even in the (one-photon) weak-field limit starting from a single vibrational eigenstate. Thus, phase dependence in the interaction with a fixed energy phase-modulated pulse can persist for some time after the pulse is over. This is illustrated for the nonadiabatic process: $\mathrm{I}+{\mathrm{Br}}^{*}\ensuremath{\leftarrow}\mathrm{IBr}\ensuremath{\rightarrow}\mathrm{I}+\mathrm{Br}$, where the relative yield of excited ${\mathrm{Br}}^{*}$ can be changed by pure phase modulation. It is shown that the phase is able to influence wave-packet spreading in the continuum as well as the average internuclear distance in each channel.

The instability of plane surface of a liquid metal in an electric field is shown to arise in arbitrarily weak field, as distinct from the well-known Tonks–Frenkel instability which takes place only in sufficiently high field. Only an account for the atomic structure of the metal leads to finite strength of the critical field which provokes the instability; however, even in this case the critical field occurs essentially less than the Tonks–Frenkel field.

We present here a sketch of some numerical results offered by a micromagnetism code based on the resolution of the Landau–Lifchitz equation. We have computed equilibrium configurations and dynamic susceptibilities to a weak field for magnetic materials with non-uniform magnetization and finite size and shape: cubic particles, finite-sized films with stripe domains and platelets with in-plane magnetocrystalline anisotropy. The obtained results have been compared with analytical models and experimental results. Some non-trivial effects have been pointed out (like surface modes) and fine details can be disclosed by susceptibility maps.

The three-dimensional magnetic field structure of 137 solar active regions is studied by comparing the observed and computed chromospheric magnetograms. The model chromospheric field is obtained by extrapolating the observed photospheric field into the chromosphere with a potential (current-free) magnetic-field model in Cartesian geometry. The best correlation between the observed and the model chromospheric magnetograms is found at the height of 800 km, which also corresponds to the height of the line formation for Ca II 854.2 nm. In the weak field range, within ±300 G, most of the observed field is close to the potential field. However, departures of about 50 G are observed in a few active regions. For field values greater than ±500 G, the observed field does not always match the model. Whereas a part of this could be due to the magnetogram calibration, it might also originate from the "nonpotentiality" of the chromospheric field. In the case of long-lived active regions, which make multiple disk passages, the strong-field nonpotentiality is observed during their initial phase, and converges to a potential field configuration later.

A saturation dip has been observed recently by A. Kumar et al. [Chem. Phys. Lett. 297 (1998) 300] in degenerate four-wave mixing (DFWM) and two-color resonant four-wave mixing (TC-RFWM) spectra of jet-cooled CH. This observation suggests that expressions of the signal intensity established for double-resonance molecular spectroscopy in the weak field limit are no longer valid. While the line splitting has been explained, this is not the case for the asymmetry observed on this spectrum. Here, we clearly establish the origin of this asymmetry as resulting from the transverse molecular velocity which acts even for a small velocity component. The model conveniently reproduces line splitting and asymmetry.

In the context of the teleparallel equivalent of general relativity, we obtain the tetrad and the torsion fields of the stationary axisymmetric Kerr spacetime. It is shown that, in the slow rotation and weak field approximations, the axial-vector torsion plays the role of the gravitomagnetic component of the gravitational field, and is thus the responsible for the Lense-Thirring effect., 9 pages, no figures, to appear in Class. Quant. Grav

A quantitative model is proposed for computing the dependence on the interecho time of the NMR relaxation rate in iron-rich gray matter obtained with a Carr-Purcell-Meiboom-Gill sequence. The model consists of representing oligodendrocytes as identical magnetic spheres arranged in a spatially random pattern, and in approximating water diffusion as isotropic and unrestricted. Predictions of the model are calculated numerically using a Monte Carlo technique and, for the weak field limit, using an analytic formula. The model is shown to provide a good fit to experimental measurements of in vitro samples of monkey brain at field levels of 1.0 T and 1.5 T. These field levels are not sufficient to fully determine the model parameters, but it is argued that this may be possible at 3.0 T. The model is potentially of value for multiple-spin-echo MRI studies of iron-related neurodegenerative disorders, such as Parkinson's disease. In particular, the model can be applied to correlate MRI data with the cellular distribution of iron in gray matter. Magn Reson Med 46:159–165, 2001. © 2001 Wiley-Liss, Inc.

Orientation in the geomagnetic field is essential for many animal species. As yet, the interaction mechanisms of this weak field with the organisms are understood only incompletely. One mechanism in question is the interaction with the photochemical reaction in the retina. We show that the visual sensitivity of man is influenced by periodic sinusoidal inversion of the vertical component of the geomagnetic field. This effect indicates visual fixation in north-south direction and shows a pronounced resonance at a period duration of 110 s. These findings should be helpful in identifying in detail the mechanisms which are influenced by the geomagnetic field.

Monte Carlo simulations were performed to examine the dc magnetron discharge that creates anomalous erosion at the boundary of the curved and straight sections of a rectangular magnetron. In order to examine the cause of anomalous erosion, we performed a series of simulations describing the strong and weak field regions without the curved section. The erosion profiles were calculated under differing magnetic field distributions. We found that anomalous erosion occurs under a magnetic field of more than 200 G. We also found that the cause of anomalous erosion is the weak magnetic field at the curved section as compared to that at the straight section. We confirmed that anomalous erosion does not occur in the case of a rectangular magnetron having a uniform magnetic field. In order to avoid anomalous erosion, the uniformity of the magnetic field has to be within 10% where the vertical component of the magnetic field at the target surface is zero.

The effect of pressure on the luminescence spectrum of the weak field system Cr3+ : LiTaO3 is presented. By using pressure to induce a low to high crystal field strength transition, we demonstrate the ability of pressure to identify distinct dopant bonding environments in luminescent materials.

Frequency conversion process is studied in a medium of atoms with a $\Lambda$ configuration of levels, where transition between two lower states is driven by a microwave field. In this system, conversion efficiency can be very high by virtue of the effect of electromagnetically induced transparency (EIT). Depending on intensity of the microwave field, two regimes of EIT are realized: ''dark-state'' EIT for the weak field, and Autler-Townes-type EIT for the strong one. We study both cases via analytical and numerical solution and find optimum conditions for the conversion., Comment: 15 pages, 5 figures

We report on a two-photon resonant three-photon ionisation experiment performed on atomic barium with a sequence of two identical not transform-limited laser pulses in the weak field regime. We show that our results, obtained by a multimode nanosecond laser source, can be reproduced theoretically by using much shorter transform-limited pulses with the same spectral bandwidth.

In order to assess the effects of weak-field magnetic stimulation on brain electrical activity in epileptics, three patients suffering from mesial temporal lobe epilepsy (MTLE) were exposed to DC magnetic fields of 0.9 and 1.8 millitesla (mT). The EEG activity was recorded simultaneously from intracranial electrodes inserted through the foramen ovale (FO) and scalp electrodes. Significant enhancement of interictal epileptiform activity was observed in two patients, while in one patient, magnetic stimulation resulted in the cessation of interictal spike/wave trains.

Active region NOAA 8038 was observed from 10 to 13 May, 1997 using the USO solar video magnetograph. During this period, the active region was mostly inactive, and gave rise to only a single notable flare of 1N/C1.3 class on May 12, 1997/04:45 UT. The flare occurred in a weak field location, but new emerging fluxes were observed prior to the flare onset. Horizontal motions of the network photospheric magnetic fluxes were inferred using USO and SOHO magnetograms, and velocities in the range 300 - 800 m s 1 were estimated. The initial flare brightening was observed at the flux cancellation site where magnetic field gradients were found to increase. Detailed analyses of flux motions, cancellation and their relation with the flare are presented.

Steady-state dynamics of a Lambda atom driven by two coherent fields is studied for arbitrary detunings, arbitrary incoherent pumping and coherent driving intensities. Effects of a strong probe on EIT are worked out. Features of EIT and LWI are presented in a new physical picture on the basis of the concepts of quantum interference and coherence. In the weak field regime, an absorption-gain profile is the subtraction of two Lorentzians with the same central frequency but different widths and heights. This case is mostly the result of quantum interference and coherence rather than the result of Autler–Townes level splitting. In a strong field regime, however, the profile is the addition of two Lorentzian-like components with different central frequencies but the same width, where Autler–Townes splitting and quantum interference are equally important.

A large number of epidemiological and experimental studies suggest that prolonged (>100 s) weak 50-60-Hz electric and magnetic field (EMF) exposures may cause biological effects(NIEHS Working Group, NIH, 1998; Bersani, 1999). We show, however, that for typical temperature sensitivities of biochemical processes, realistic temperature variations during long exposures raise the threshold exposure by two to three orders of magnitude over a fundamental value, independent of the biophysical coupling mechanism. Temperature variations have been omitted in previous theoretical analyses of possible weak field effects, particularly stochastic resonance (Bezrukov and Vodyanoy 1997a. Nature. 385:319-321; Astumian et al., 1997 Nature. 338:632-633; Bezrukov and Vodyanoy, 1997b. Nature. 338:663; Dykman and McClintock, 1998. Nature. 391:344; McClintock, 1998;. Gammaitoni et al., 1998. Rev. Mod. Phys. 70:223-287). Although sensory systems usually respond to much shorter (approximately 1 s) exposures and can approach fundamental limits (Bialek, 1987 Annu. Rev. Biophys. Biophys. Chem. 16:455-468; Adair et al, 1998. Chaos. 8:576-587), our results significantly decrease the plausibility of effects for nonsensory biological systems due to prolonged, weak-field exposures.

The weak-field version of optimal control theory is applied to the design of laser pulses to achieve control over product formation. Computations on the optimal control of the two-photon dissociation of Na2, yielding the products Na(3s)+Na(3p) and Na(3s)+Na(4s), are described. The optimization is performed by maximizing either the difference between, or the ratio of, the probabilities of producing a product in these two channels. The dependence of the quality of control on the potential surfaces involved is also investigated as is the strategy through which optimized control is achieved.

We present a uniform treatment of (the weak field) preparation and evolution of a superposition of overlapping resonances. We show that the manner of (the optical) preparation has profound effect o...

A weak field DNP study of 4-hydroxy-2,2,6, 6-tetramethyl-1-piperidinyloxy (4-hydroxy-TEMPO), 4-amino-2,2,6, 6-tetramethyl-1-piperidinyloxy (4-amino-TEMPO), and 2, 2-Di(4-tert-octylphenyl)-1-picrylhydrazyl (DPPH) free radicals invarious solvents was performed at 1.53 mT using a doubleresonance spectrometer. pi transitions, in which the RF fieldhas a component perpendicular to the static magnetic fieldB0, and final sigma transitions, in which the RF field has a component parallel to B0, were recorded. In order to observe thefinal sigma transitions a new probe head was designed. The final sigma transitions were obtained at the frequencies expected from theoretical calculations. However, the results obtained for the observed enhancements deviated from the values expectedtheoretically.

The weak field dielectric aging behaviours of lead magnesium niobate (Pb[Mg1/3Nb2/3]O3) ceramics have been extensively investigated. In this paper, however, we focused on the dielectric aging of a Mg and Mn doped PMN ceramic under various alternating current (ac) fields. It is found that the strong ac fields generally suppress the aging rate, particularly at low measurement frequencies.

It is shown that in the weak field approximation solutions of Brans-Dicke equations are simply related to the solutions of General Relativity equations for the same matter distribution. A simple method is developed which permits to obtain Brans-Dicke solutions from Einstein solutions when both theories are considered in their linearized forms. To illustrate the method some examples found in the literature are discussed., Comment: 12 pages, latex, no figures

The mean displacement moments for the strong field trapping model are calculated. Their asymptotic behaviour is 〈Xn(t)〉 ∼ (Vefft)n, where Veff is an effective drift velocity. This is in sharp contrast with the weak field case, for which 〈X n (t)〉 ∼ t n 3 . The mean survival (first passage) time and the upstream and downstream trapping probabilities are also obtained.

A domain wall model is proposed for relaxor ferroelectrics typified by Pb(Mg1/3Nb2/3. Under a large applied field or a large internal field, domain walls move over a long distance by overcoming localized barriers. This movement is responsible for the hysteresis loop and depolarization at temperatures below T max. The activation volumes obtained by analyzing the coercive field dependence on temperature and frequency suggest that the barriers encountered by the domain walls are of the size of 1000 unit cells, and they increase as the relaxor becomes more like a normal ferroelectric. Since polarization is usually incomplete in relaxors even under a large polarizing field, depolarization readily occurs without the need of nucleating new domains. Domain walls are also responsible for permittivity peaks at high temperature under a weak field. However, without a strong field, domain walls are partially pinned by barriers and can only oscillate within the unpolarized regions between barriers. The mobilit...

I consider the weak field limit (WFL) of bimetric MOND (BIMOND): the lowest order in the small departures Hmn and H'mn from double Minkowski space-time. In particular, I look at propagating solutions, for a favorite subclass of BIMOND. The WFL splits into two sectors for two linear combinations, Hmn+ and Hmn-, of Hmn and H'mn. The Hmn+ sector is equivalent to the WFL of general relativity (GR), with its gauge freedom, and has the same vacuum gravitational waves. The Hmn- sector is fully nonlinear even for the weakest Hmn-, and inherits none of the coordinate gauge freedom. The equations of motion are scale invariant in the deep-MOND limit of purely gravitational systems. In these last two regards, the BIMOND WFL is greatly different from that of other bimetric theories studied to date. Despite the strong nonlinearity, an arbitrary pair of harmonic GR wave packets of Hmn and H'mn moving in the same direction, is a solution of the (vacuum) BIMOND WFL., 5 pages, version to be published in Phys. Rev. D

The symbiotic X-ray binary 4U 1954+319 is a rare system hosting a peculiar neutron star (NS) and an M-type optical companion. Its ~5.4h NS spin period is the longest among all known accretion-powered pulsars and exhibited large (~7%) fluctuations over 8 years. A spin trend transition was detected with Swift/BAT around an X-ray brightening in 2012. The source was in quiescent and bright states before and after this outburst based on 60 ks Suzaku observations in 2011 and 2012. The observed continuum is well described by a Comptonized model with the addition of a narrow 6.4 keV Fe Kalpha line during the outburst. Spectral similarities to slowly rotating pulsars in high-mass X-ray binaries, its high pulsed fraction (~60-80%), and the location in the Corbet diagram favor high B-field (>~1e+12 G) over a weak field as in low-mass X-ray binaries. The observed low X-ray luminosity (1e+33-1e+35 erg/s), probable wide orbit, and a slow stellar wind of this SyXB make quasi-spherical accretion in the subsonic settling regime a plausible model. Assuming a ~1e+13 G NS, this scheme can explain the ~5.4 h equilibrium rotation without employing the magnetar-like field (~1e+16 G) required in the disk accretion case. The time-scales of multiple irregular flares (~50 s) can also be attributed to the free-fall time from the Alfven shell for a ~1e+13 G field. A physical interpretation of SyXBs beyond the canonical binary classifications is discussed., 20 pages, 18 figures, 3 tables, accepted for publication in the Astrophysical Journal

Introduction Migratory birds travel spectacular distances each year, navigating and orienting by a variety of means, most of which are poorly understood. Among these is a remarkable ability to perceive the intensity and direction of the Earth's magnetic field (Mouritsen and Ritz, 2005; Wiltschko and Wiltschko, 2006; Johnsen and Lohmann, 2008). Biologically credible mechanisms for the detection of such a weak field (25–65 μT) are scarce, and in recent years just two proposals have emerged as front-runners. One, essentially classical, centers on clusters of magnetic iron-containing particles in the upper beak, which appear to act as a magnetometer for determining geographical position (Kirschvink and Gould, 1981; Kirschvink et al. , 2001; Fleissner et al. , 2007; Solov'yov and Greiner, 2007; Walker, 2008; Solov'yov and Greiner, 2009a, b; Falkenberg et al. , 2010). The other relies on the quantum spin dynamics of transient photoinduced radical pairs (Schulten et al. , 1978; Schulten, 1982; Schulten and Windemuth, 1986; Ritz et al. , 2000b; Cintolesi et al. , 2003; Moller et al. , 2004; Mouritsen et al. , 2004; Heyers et al. , 2007; Liedvogel et al. , 2007b, a; Solov'yov et al. , 2007; Feenders et al. , 2008; Maeda et al. , 2008; Solov'yov and Schulten, 2009; Ritz et al. , 2009; Rodgers and Hore, 2009; Zapka et al. , 2009). Originally suggested by Schulten in 1978 (Schulten et al. , 1978) as the basis of the avian magnetic compass sensor, this mechanism gained support from the subsequent observation that the compass is light dependent (Wiltschko et al. , 1993) (for a review see e.g. (Wiltschko et al. , 2010)).

We discuss the Wilson renormalization group approach to the effective action for low $x$ physics. It is shown that in the linearized, weak field regime the RG equation reduces to the BFKL equation for the evolution of the unintegrated gluon density. We discuss the relation of this approach with that of Lipatov., Comment: 23 pages, latex, requires axodraw.sty

Solutions of 4-hydroxy-TEMPO(TANOL) in water and water-soyabean oil were investigated in the concentration range 0.1 mM-10mM. Dynamic nuclear polarization (DNP) and electronic relaxation time T1e measurements were performed at each well resolved hyperfine line. In the TANOL/water-soyabean oil solutions, the effect of the presence of soyabean oil was an increase in the measured relaxation rates and a decrease in the observed enhancements. In addition, the observed enhancements diminished in time. For all of the samples, the relaxation rates decreased as the frequency of the transition increased.

We develop a quantum-mechanical approach to the photoassociation phenomenon in a sample of cold atoms initially at thermal equilibrium with temperature T. We calculate the rate of formation of molecules in the weak field regime using a perturbative approach. Analytical expressions are obtained for the overlap between the initial and final molecular wavefunctions, and are shown to agree with numerical calculations. The photoassociation rate is found to decrease with increasing atomic mass m, from Li to Cs. Also considered is the heating of the atomic sample through spontaneous photodissociation.

Heller’s expression for the absorption cross-section in the weak field limit is extended to cases where the total Hamiltonian contains a strong time-dependent component, supplemented by a weak field. A very similar expression to the original case then results when the (t,t) formalism is used; one only needs to construct a correlation function for the system without the weak field, and use it to extract the absorption probability for any value of the weak-field frequency (or pulse shape). In addition, a numerical approach for extracting Floquet states without full-matrix diagonalization is demonstrated, by filtering (or filter-diagonalization) a single wave function (or the correlation function) propagated under the (t,t) Hamiltonian.

The weak field approximation is applied to the Ernst equations in the magnetovac case. The global gravitational solution induced by the magnetic field of a spherical solenoid is found. Effects like the acceleration at rest and the tension in the solenoid's shell are studied.

A compensation method aiming to form a weak field area (a dark spot) in an antenna near region over a broad frequency band is considered. The need for broadband field compensation arises in cases when it is necessary to protect the human body against irradiation, for example, if a mobile transmitter is located in a vehicle in the vicinity of several users. It is shown that broadband field compensation can be achieved in structures, in which the needed antiphase fields are created by antennas of identical type, by radiators located at equal distance from the compensation point, or by flat reflectors.

The order dependent mapping method, its convergence has recently been proven for the energy eigenvalue of the anharmonic oscillator, is applied to re-sum the standard perturbation series for Stark effect of the hydrogen atom. We perform a numerical experiment up to the fiftieth order of the perturbation expansion. A simple mapping suggested by the analytic structure and the strong field behavior gives an excellent agreement with the exact value for an intermediate range of the electric field, $0.03\leq E\leq0.25$. The imaginary part of the energy (the decay width) as well as the real part of the energy is reproduced from the standard perturbation series., Comment: 14 pages, 8 figures

Two formulas are obtained for the weak-field Hall conductivity based on different configurations of a magnetic field in the long-wavelength limit: \(\sigma _{xy}^{(x)}\) and \(\sigma _{xy}^{(y)}\) ...