Search Results - (Author, Cooperation:W. Doyle)

2014-01-17

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Brain/*anatomy & histology/*physiology ; Brain Mapping ; Female ; Frontal Lobe/physiology ; Functional Laterality/physiology ; Hearing/physiology ; Humans ; Language ; Male ; Models, Neurological ; Psychomotor Performance/*physiology ; Speech/*physiology ; Speech Perception/*physiology ; Temporal Lobe/physiology

0022-4545

Psychology

Sociology

1365-2133

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Preliminary findings attesting to the successful therapeutic use of biofeedback training in reducing symptoms of chronic hyperhidrosis are reported. Eleven of the fourteen adult patients trained with biofeedback were able to demonstrate clinical improvement in their excessive sweating 6 weeks after termination of treatment. Relaxation was suggested as the active ingredient in the biofeedback treatment effect. These findings support a recent report of the successful use of biofeedback in treating patients with dyshidrotic eczema.

Electronic Resource

1573-3521

associative learning ; habit ; health behavior ; reinforcement

Springer Online Journal Archives 1860-2000

Medicine

Psychology

Abstract Habit is defined as a firmly established behavior pattern marked by increasing automaticity, decreasing awareness, and partial independence from reinforcement. Reinforcement is viewed as of primary importance in the acquisition of behavior, whereas principles of associative learning enter to complement reinforcement in the maintenance of behavior. Habit is seen as a mechanism for short-circuiting the reinforcement process to avoid its overload and for providing the organism with speed and stability of response instead of the variability offered by reinforcement. The implications of this definition of habit for acquisition and alteration of health behavior are discussed; examples include smoking, obesity, alcoholism, and coronary-prone (type A) behavior.

Electronic Resource

1573-3521

Springer Online Journal Archives 1860-2000

Medicine

Psychology

Electronic Resource

1573-3521

MMPI ; chronic pain ; personality

Springer Online Journal Archives 1860-2000

Medicine

Psychology

Abstract A multivariate clustering procedure was used to identify replicable, homogeneous MMPI profile subgroups among three independent cohorts of male (N=233) and female (N=315) low back pain (LBP) patients. Three subgroups were replicated across all male cohorts and four subgroups were replicated across all female cohorts. Multiple discriminant analysis showed that for both male and female patients between-subgroup variability was significantly greater than within-subgroup variability. The results suggest that LBP patients may not be solely characterized by MMPI profiles featuring the “conversion V” configuration. Examination of the profile subgroups also suggests there may be distinct, pain-related, behavioral attributes associated with each subgroup which might have important implications for practitioners' choice of treatment modalities. Suggestions are made for research regarding the development of specific, optimal treatments for various LBP patient subgroups.

Electronic Resource

1573-3521

Springer Online Journal Archives 1860-2000

Medicine

Psychology

Electronic Resource

1573-3521

Springer Online Journal Archives 1860-2000

Medicine

Psychology

Electronic Resource

1089-7550

AIP Digital Archive

Physics

Single-layer Fe-N films were deposited onto DC biased glass substrates at room temperature by reactive rf magnetron sputtering in an N2-Ar atmosphere. The Ar pressure was fixed at 6 mTorr and the properties were investigated as a function of N2 flow rate (R). X-ray diffraction and transmission electron diffraction were used to identify phases in the films. At R=0, the saturation magnetic moment density σS measured in a vibrating-sample magnetometer (VSM) was 210 emu/g, within experimental error equal to the value for bulk α-Fe, and only a single phase with the bulk lattice constant of α-Fe was detected. At R=5 sccm, σS=227 emu/g, and an α-Fe(N) phase with a ∼1% expanded lattice constant was detected. At R=15 sccm, σS reached a maximum of 247 emu/g and x-ray and transmission electron diffraction gave clear evidence of the Fe16N2 phase in addition to α-Fe(N). At R=30 sccm, σS dropped to 196 emu/g, and the diffraction data showed α-Fe, α-Fe(N), and a significant fraction of Fe4N. The value of σS calculated from the volume fractions of each phase estimated from transmission electron microscopy statistical sampling of single grain diffraction quantitatively agreed, within the experimental error, with the measured value.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

To further investigate the relationship between the giant magnetoresistance (GMR), anisotropic magnetoresistance (AMR), and antiferromagnetic (AFM) coupling found in magnetic multilayers we have deposited NiFe/Cr multilayers onto rectangular Corning 7059 glass substrates at ambient temperatures. Uniaxial anisotropy was induced by applying a 90 Oe field along the length of the substrate strips during deposition and in all cases a 50–100-A(ring)-thick Cr underlayer was used. For Cr interfilms 9–12-A(ring) thick, the multilayers were found to have hard axis saturation fields of 90–200 Oe and easy axis hysteresis loops which exhibit a complex behavior dependent on whether the multilayer is composed of an even or an odd number of NiFe films. Both of these effects result from AFM coupling of the NiFe films. The magnetoresistive (MR) behavior was also found to be complex and dependent on the number of NiFe films in the multilayer. A theoretical model based on coherent rotation and including AFM coupling between the NiFe films has been developed and both the hysteresis loops and MR of the multilayers calculated. From these calculations it has been found that, despite the existence of AFM coupling, the experimentally observed magnetoresistive behavior can be described using only AMR. Thus the existence of AFM coupling does not result in GMR NiFe/Cr multilayers. This is discussed in terms of spin filtering at the multilayer interfaces.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

The frequency dependence of the transverse biased permeability μ't(f ) has been measured up to 250 MHz in thin (0.044 μm) and thick (2.1 μm) unpatterned sputtered permalloy films with uniaxial anisotropy. In these films, the initial permeability along the hard axis can be described by the classical eddy current damping model assuming uniform rotation. For both films, μ't at low frequency agrees reasonably well with Hoffman's ripple model assuming appropriate values for the structure factor. In the thin film, μ't(f ) is independent of frequency within experimental error up to at least 250 MHz. However, in the thick film μ't(f ) decreases more rapidly with frequency than can be explained by classical eddy currents, when the transverse bias field HB is not very large compared to the net anisotropy field. The value of HB at which μ't(f ) reaches a maximum amplitude is also found to increase monotonically with increasing frequency, also inconsistent with simple eddy current predictions. It is suggested that the formation of ripple walls leads to anomalous eddy current losses similar to that observed in bulk materials.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

Disordered suspensions of conducting particles exhibit substantial permittivity enhancements beyond the predictions of the Clausius–Mossotti equation and other purely dipolar approximations. The magnitude of the enhancement depends upon the shape of the particles. A recently developed effective cluster model for spherical particles [Phys. Rev. B 42, 9319 (1990)] that treats a disordered suspension as a mixture, or mesosuspension, of isolated spheres and close-packed spherical clusters of arbitrary size is in excellent agreement with experiments on well-stirred suspensions of spheres over the entire accessible range of volume loading. In this paper, the effective cluster model is extended to be applicable to disordered suspensions of arbitrarily shaped conducting particles. Two physical parameters are used to characterize a general suspension: the angular average polarizability of an isolated particle, and the volume loading at closest packing of the suspension. Multipole interactions within the clusters are treated exactly. External particle-shape-dependent interactions between clusters and isolated particles are treated in the dipole approximation in two ways: explicitly, using the Clausius–Mossotti equation, and implicitly, using the Wiener equation. Both versions of the model are used to find the permittivity of a monodisperse suspension of conducting spheroids, for which the model parameters can be determined independently. The two versions are in good agreement when the axial ratio of the particles is not extreme.The Clausius–Mossotti version of the model yields a mesoscopic analogue of the dielectric virial expansion. It is limited to small volume loadings when the particles have an extremely nonspherical shape. The Wiener equation version of the model holds at all volume loadings for particles of arbitrary shape. Comparison of the two versions of the model leads to a simple physical interpretation of Wiener's equation. The models are compared with experiments of Kelly, Stenoien, and Isbell [J. Appl. Phys. 24, 258 (1953)] on aluminum and zinc particles in paraffin, with Nasuhoglu's experiments on iron particles in oil [Commun. Fac. Sci. Univ. Ankara 4, 108 (1952)], and with new X-band and Kα-band permittivity measurements on Ni-Cr alloy particles in a polyurethane binder.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

Current thin film high performance media have very high viscosity and consequently a significant dependence of the remanent coercivity HCR on the measurement time. The fluctuation field Hf is a parameter commonly used to describe thermal effects and is defined in terms of the magnetic viscosity and the irreversible susceptibility χIRR. Previous work has shown that the viscosity is independent of time down to 10−8 s. Here we examine the time dependence of χIRR on a variety of particulate and high density thin film media at both long times (5–1000 s) and very short times (1–20 ns). It was found that χIRR was independent of time down to ∼10 ns. However, below 10 ns, χIRR decreased rapidly, signaling the probable onset of gyromagnetically controlled switching. © 1999 American Institute of Physics.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

In earlier publications it has been shown that the value and direction of the magnetic anisotropy in FeTaN films can be changed by thermal annealing in a dc magnetic field. These films have potential as future write head materials, and this type of instability could pose a problem. In the current work dc and ac annealing experiments have been performed to test the stability of the anisotropy. Our results confirm the model of interstitial-nitrogen-induced anisotropy in the FeTaN films by illustrating that the magnitude of the anisotropy is reduced at higher temperatures, and that the direction of the anisotropy is stable if the time in the switched direction is less than the time required for diffusion of the nitrogen to a different interstitial position. The direction is stable at 100 °C, for square wave magnetic field switching between the easy and hard axes, at frequencies above 500 Hz. The direction is unstable at 100 °C for switching between the hard axes at frequencies less than 5 kHz. © 2000 American Institute of Physics.

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1089-7550

AIP Digital Archive

Physics

FeTaN single-crystal thin films were grown in order to investigate the dependence of the crystalline anisotropy constant, K1, on the Ta and nitrogen content. Films with 5 and 10 wt % Ta and different nitrogen contents were prepared by dc sputtering on MgO(100) substrates at elevated temperatures. The film/substrate orientation was (100)(parallel)(100) and [100](parallel)[110]. The values of K1 were determined by measuring the in-plane angular dependence of the ferromagnetic resonance spectra and agreed very well with the values obtained from torque measurements, indicating that the total volume was biaxial cubic material. The hysteresis loops were characteristic of biaxial anisotropy and the anisotropy fields estimated from magnetization curves were consistent with the resonance and torque data. In Fe, K1 was (4.8±0.1)×105 ergs/cc in good agreement with the bulk value. In FeTa, K1 decreased to (4.4±0.1)×105 and (3.5±0.1)×105 ergs/cc for 5 and 10 wt % Ta content, respectively, and further to (2.7±0.1)×105 and (2.1±0.1)×105 ergs/cc in (Fe95Ta5)N depending on the nitrogen content. The nitrogen addition to Fe90Ta10 resulted in the formation of epitaxial (FeTa)4N which is an fcc structure with a negative K1 of (−1.5±0.2)×105 ergs/cc. © 1996 American Institute of Physics.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

Measurement of P, the percentage reduction in remanence after the application of 1≤n≤104 reverse field pulses of width 0.6 ns ≤ τ ≤9 ns, are reported for five particulate tape samples including γ-Fe2O3, Co-γFe2O3, Fe, and two different barium ferrites. For τ(approximately-greater-than)τc, P depended only on nτ. It increases quite rapidly at small values of nτ depending on the media and then at higher values of nτ approximately linearly with log(nτ). In the linear regime, the decrements δ (% change/decade) agree within experimental error with the quasistatic values obtained from viscosity measurements between 10 and 100 s. Considering the arbitrariness of the logarithmic assumption, it is remarkable that the decrement is the same over eleven orders of magnitude. The reduction in P at τ〈τc is evidence for time-limited switching as reported previously. However, the dependence of P on nτ for small nτ cannot be explained by the usual viscosity model but is consistent with reptation, a phenomenon suggested by Néel.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

Ferromagnetic resonance spectra have been measured for three barium ferrite tapes at 34.5 GHz for two different orientations of the tapes with respect to the static and microwave fields. The orientation distributions in the tapes have been measured using x-ray diffraction, and these distributions have been used to calculate the spectra using the Landau–Lifshitz equation. The anisotropy energy, damping constant, and volume packing fraction have been used as adjustable parameters in the calculations. Calculated spectra were in good agreement with measurements. Anisotropy constants and damping constants determined from the fits are consistent with results reported for fine particle assemblies.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

In our previous work, it was shown that in antiferromagnetically coupled multilayered films there is the possibility of the appearance of both Bloch-type walls and Néel-type walls at the center of which the magnetizations point parallel (PB,PN) or antiparallel (AB,AN) to each other between the adjacent layers when a high field is applied in one direction and then removed. Here it is shown that the shift of the walls in each layer from their vertical alignment will give substantially lower energy for the AB walls and for the PN walls, giving rise to self-stabilization, and that the effect is greater for the latter than the former for [Co/Cu]N systems with the thickness ratio tCo/tCu=2. This will result in a greater possibility of the PN walls formation than was expected in the previous work. In the region where the number of layers and the coupling field are of practical interest, Néel walls are favored, and AN walls have lower energy than PN walls. In this case, it is likely that the transition of the wall types from PN to AN and vice versa will occur during the magnetization process, which will cause noise in sensor applications.

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1089-7550

AIP Digital Archive

Physics

Siegmann et al. have reported that the magnetization in a perpendicularly oriented CoPt film with a uniaxial anisotropy field of 20 000 Oe was reversed when the film was exposed to a 20 000 Oe in-plane pulsed field lasting only 6 ps. From a calculation based on the Gilbert form of the Landau–Lifshitz equation (LLG), it is shown that the experimental result is consistent with the LLG model even for values of the damping constant α as larger as 0.5. The dependence of the switching time on the anisotropy field and the applied field are presented as a function of α and the angle β between the applied field and the easy axis. Experiments are suggested which could illuminate the damping mechanism at these very short times. © 1996 American Institute of Physics.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

New results on the switching speed limit in high coercivity particulate magnetic media have recently been reported using pulse fields with widths t〈1 ns. Because the pulse amplitude is presently limited to 〈950 Oe, switching measurements on media with higher coercivities were carried out in the presence of a dc bias field HB and the switching constant Sw at zero bias field estimated by extrapolating the data at several high bias fields to HB=0. The sensitivity of Sw to HB was significant particularly in barium ferrite so it is prudent to examine this dependency more carefully in a lower coercivity system in which Sw can be measured from 0≤HB≤HCR and HCR is the remanent coercivity. The results (Fig. 1) for a standard γ-Fe2O3 iron oxide tape with HCR=375 Oe show a nearly linear dependence of Sw on HB except for HB/HCR≥0.7 and validate our earlier speculation that switching in barium ferrite particles is significantly slower than in metal particles. The experimental results will be compared to the calculated switching time as a function of HB expected for an appropriate distribution of uniaxial, single domain particles.

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