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Commercially available mirrors for scanning long-wavelength beams are too large for high-speed imaging. There is a need for a smaller, more agile pointing apparatus to provide images in seconds, not minutes or hours. A fast long-wavelength beam steerer uses a commercial micro-electro-mechanical system (MEMS) mirror controlled by a high-performance digital signal processor (DSP). The DSP allows high-speed raster scanning of the incident radiation, which is focused to a small waist onto the 9mm(2), gold-coated, MEMS mirror surface, while simultaneously acquiring an undistorted, high spatial-resolution image of an object. The beam steerer hardware, software and performance are described. The system can also serve as a miniaturized, high-performance long-wavelength beam chopper for lock-in detection.

Objective To review the results of percutaneous transluminal renal artery angloplasty (PTRA), including technical success and clinical outcome, at Mayo Clinic Rochester. Design We retrospectively reviewed our experience with 320 patients who underwent PTRA for stenosis of 396 arteries during a 14-year period. Material and Methods We reviewed medical records and angiograms of patients who underwent PTRA at Mayo Clinic Rochester between January 1980 and December 1993. The patients were divided into four groups, based on clinical history and anglographic appearance of the stenosing lesion: renal artery atherosclerosis (ASO group), fibromuscular dysplasia (FMD group), previous renal artery bypass or endarterectomy, and renal artery stenosis in a solitary kidney. Technical results of the PTRA were determined by evaluation of angiograms obtained before and after the procedure. Data on patient demographics, blood pressure, antihypertensive medications, and serum creatinine were recorded for the period preceding PTRA, after the procedure, and at last follow-up. Results All groups had statistically significant reductions in mean arterial pressure and antihypertensive medications after PTRA. The percentage of patients who benefited after renal artery angioplasty was 70% for patients with ASO (8.4% cured), 63% for patients with FMD (22% cured), 53.8% for patients with prior surgical revascularization (23.1 % cured), and 91.7% for patients with a solitary kidney (0% cured). No significant overall change in serum creatinine level was noted after the procedure in any group. Complications were comparable to those reported in other studies. The 30-day all-cause mortality rate was 2.2 % for the current study, all deaths occurring in the ASO group. Conclusion PTRA rarely leads to a "cure" of renovascular hypertension but provides effective control of blood pressure and decreases the medication requirements in selected patients.

A magneto-optic Kerr effect scanning near-field optical microscope is used to image a stripe domain wall in a Co/Pt multilayer sample. The microscope is an improved version of a type previously reported, which uses light scattering from surface plasmons in 20 - 40 nm Ag particles as a near-field probe. Data is presented for both the probe intensity and polarization contrast as a function of probe/sample spacing. Oscillatory behavior in both sets of data is reasonably explained with a simplified model of optical interference.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The prevalence of chronic impairment of the respiratory system and ventilatory capacity was studied in 81 sanitation workers. In addition, the prevalence of chronic respiratory symptoms was studied in 65 non-exposed control workers. Among the sanitation workers the prevalence of most of the chronic respiratory symptoms was statistically higher than among the controls. The sanitation workers--smokers had a significantly higher prevalence of chronic cough, chronic phlegm and chest tightness than the non-smoking sanitation workers (P0.05). The sanitation smokers exposed for more than 10 years had significantly higher prevalences of nasal catarrh (P0.01) and sinusitis (P0.05) than those with a shorter exposure. FVC and FEV1 were significantly reduced in sanitation workers exposed for more than 10 years in relation to predicted normal values. These differences were not significant for FEF50 and FEF25. Our results suggest that sanitation workers may develop chronic respiratory symptoms and lung function changes, in the first place those of FVC and FEV1.

The aim of the study was to evaluate the interrelation between the levels of growth hormone (GH), prolactin (PRL), somatomedin-C (Sm-C) and melatonin determined at 3 h intervals over a 24 h period (8.00, 11.00, 14.00, 17.00, 20.00, 23.00, 2.00 and 5.00) in 8 acromegalic patients after radiotherapy. The circadian rhythms and the interrelation between hormone and Sm-C levels were evaluated using Halberg's cosinor method and the correlation analysis, respectively. We observed a total abolition of melatonin rhythm with significantly lower nocturnal values in all patients which could be due to earlier radiotherapy.

Prevalencija kroničnih respiracijskih simptoma i ventilacijska funkcija pluća ispitivane su u 81 radnika na čišćenju ulica i odvažanju otpada. Prevalencija kroničnih respiracijskih simptoma ispitivana je i u 65 radnika neizložene kontrolne skupine. Utvrđena je značajno veća prevalencija većine kroničnih respiracijskih simptoma u izloženih nego u radnika kontrolne skupine. U izloženih pušača utvrđena je značajno veća prevalencija kroničnog kašlja, kroničnog iskašljaja i stezanja u prsima nego u izloženih nepušača (P, The prevalence of chronic impairment of the respiratory system and ventilatory capacity was studied in 81 sanitation workers. In addition, tie prevalence of chronic respiratory symptoms was studied in 65 non-exposed control workers. Among the sanitation workers the prevalence of most of the chronic respiratory symptoms was statistically higher than among the controls. The sanitation workers - smokers had a significantly higher prevalence of chronic cough, chronic phlegm and chest tightness than the non-smoking sanitation workers (P

We have performed spin-transfer torque switching experiments with a large number of trials (up to 107 switching events) on nanoscale MgO magnetic tunnel junctions in order to test the validity and the limits of the thermal activation model for spin-torque-assisted switching. Three different methods derived from the model (“read disturb rate,” “switching voltage versus pulse duration,” and “switching voltage distribution” measurements) are used to determine the thermal stability factor and the intrinsic switching voltage. The results obtained from the first two methods agree well with each other as well as with values obtained from quasistatic measurements, if we use only the data for which the voltage is smaller than approximately 0.8 of the intrinsic switching voltage. This agreement also shows that, in our samples, in the low voltage region, the influence from other factors contributing to the switching (such as current-induced heating and field-like torque) is negligible. The third method (switching voltage distribution measurements) yields incorrect values for the time-scales (

The present reports on the effects of various levels of the endocrine system on the course of bronchial asthma are reviewed. Hypophyseal function in production of certain hormone and functioning of the hypothalamo, hypophyseal-thyroid, -adrenal, and -gonadal axis are discussed. Changes in the functions of endocrine glands may modify the course of allergic diseases.

The novel concept of offset susceptibility ${\mathrm{\ensuremath{\chi}}}_{0}$ is presented for superconductors in applied fields ${\mathrm{H}}_{\mathrm{dc}}$+${\mathrm{H}}_{\mathrm{ac}}$ sin\ensuremath{\omega}t. ${\mathrm{\ensuremath{\chi}}}_{0}$ represents the dc component of the time-dependent magnetization M(t). For sintered ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$, ${\mathrm{\ensuremath{\chi}}}_{0}$ was measured as a function of ${\mathrm{H}}_{\mathrm{ac}}$, ${\mathrm{H}}_{\mathrm{dc}}$, and temperature using a Hall probe magnetometer and Fourier analysis. For intragranular diamagnetism, ${\mathrm{\ensuremath{\chi}}}_{0}$ behaves as the real part of complex fundamental susceptibility ${\mathrm{\ensuremath{\chi}}}_{1}^{\ensuremath{'}}$, confirming a London-like field penetration. However, ${\mathrm{\ensuremath{\chi}}}_{0}$ arising from intergranular coupling is positive at temperatures just below the onset of the coupling transition, in good agreement with theoretical predictions of a simplified Kim critical-state model of magnetization.

Bulk and local magnetoresistive responses in Ni-Fe thin films were measured as a function of applied magnetic field and field angle. The measurements were made using a four-probe resistance measurement system, which consisted of two scanning microprobes for voltage taps, each less than 1 mu m in tip diameter. The scanning resolution of the microprobes was 0.5 mu m. The system was used to determine domain formation and motion in magnetoresistive read heads. Longitudinal fields, produced by demagnetizing or external field components, may cause domain formation and subsequent domain-wall motion (and annihilation). This leads to Barkhausen noise, which is detrimental to the performance of the device as a magnetic read head. Experimental results for both the bulk and local responses were in qualitative agreement with micromagnetic theory. >

We measure oscillator phase from the zero crossings of the voltage vs. time waveform of a spin torque nanocontact oscillating in a vortex mode. The power spectrum of the phase noise varies with Fourier frequency $f$ as $1/f^2$, consistent with frequency fluctuations driven by a thermal source. The linewidth implied by phase noise alone is about 70 % of that measured using a spectrum analyzer. A phase-locked loop reduces the phase noise for frequencies within its 3 MHz bandwidth., 6 pages, 5 figures, supplementary material. Submitted to {Appl. Phys. Lett.}

Circadian variation of serum triiodothyronine (T3), thyroxine (T4), corticosterone (B) and lipids was studied in male Wistar rats after one week of the starvation. The animals were adopted to 12:12 h light-dark cycle (lights on from 7.00 to 19.00 h) and tap water was available ad libitum. Blood samples were drawn at 3 h intervals along a 24 h span. The hormone levels were measured by RIA kits, plasma lipids by photometric method. The results were evaluated by cosinor method. The presence of a circadian rhythm of T3 and B was found in control rats. The starvation resulted in changed circadian rhythm of T3 with lower values of mesor and amplitude, and while acrophase shifted from 14.48 to 2.12. In addition, the starvation induced circadian rhythm of T4 with acrophase at 1.00. The circadian rhythm of B showed significantly higher values of mesor and amplitude, while acrophase shifted from 17.42 to 4.06. The concentration of lipids was changed in the animals deprived of food as compared with controls.

We present the design and fabrication of a magnetoresistive imaging system capable of scanning 256 channels simultaneously along linear ranges of either 4 or 13 mm. High speed electronics read the channels and transfer the data to a computer that builds and displays the images. The system was successfully used to image magnetic tapes for real-time forensic validation purposes and can also be applied in other noninvasive imaging applications.

We present a new digital-signal-processor-based resonance tracking system for scanned probe microscopy (SPM) imaging. The system was developed to enable quantitative imaging of mechanical properties with nanoscale spatial resolution at practical data acquisition rates. It consists of a 32-bit floating-point digital signal processor connected to a high-resolution audio coder/decoder subsystem, an rms-to-dc converter and a voltage-controlled oscillator. These components are used in conjunction with a commercial atomic force microscope to create a versatile platform for SPM mechanical mapping. Images of a glass-fibre/polymer matrix composite sample are presented to demonstrate system performance.

The spin dynamics of sub-100-nm Ni80Fe20 nanomagnets are directly measured using the magneto-optic Kerr effect and a broadband detection scheme. Elliptical dots approximately 68nm in diameter and 10nm thick were fabricated in 20×20μm2 arrays. There is approximately a factor of 2 increase in the effective linewidth when compared to a 20μm diameter continuous disk of the same material. Using micromagnetic simulations, we model the effect of dot-to-dot size variation on the effective linewidth and find that 2nm size variations are more than sufficient to account for the effective increase in linewidth.

We adapted a time-resolved magneto-optic microprobe for use with a pulsed inductive microwave magnetometer apparatus, to measure the magnetization dynamics of a thin Permalloy film at micrometer and millimeter length scales under exactly the same experimental conditions. The optical microprobe has a spatial resolution of 1 μm. We compare the data obtained over these different length scales to quantitatively determine the localized inhomogeneous contribution to magnetic damping. When measured directly with the magneto-optic technique, the inhomogeneous contributions are in agreement with the value 88±16 A/m (1.1±0.2 Oe) extrapolated from PIMM measurements of linewidth versus frequency.

We have used contact-resonance-frequency atomic force microscopy techniques to nondestructively image variations in adhesion at a buried interface. Images were acquired on a sample containing a 20nm gold (Au) blanket film on silicon (Si) with a 1nm patterned interlayer of titanium (Ti). This design produced regions of very weak adhesion (Si∕Au) and regions of strong adhesion (Si∕Ti∕Au). Values of the contact stiffness were 5% lower in the regions of weak adhesion. The observed behavior is consistent with theoretical predictions for layered systems with disbonds. Our results represent progress towards quantitative measurement of adhesion parameters on the nanoscale.

We describe our work to evaluate the nanomechanical properties of surfaces, thin films, and nanostructures using the atomic force microscope (AFM). Our approach is based on atomic force acoustic microscopy (AFAM) and involves the resonant vibrations of an AFM cantilever in contact with a sample. We first describe the basic principles of AFAM, in which local elastic‐property values are determined from the contact‐resonance frequencies using models for the cantilever dynamics and for the tip‐sample contact mechanics. Quantitative results for a variety of thin supported films ranging in stiffness from 50 to 250 GPa and as thin as 50 nm are given to illustrate our methods. Studies related to measurement accuracy involving the effects of film thickness and tip shape are also presented. Finally, we discuss new frequency‐tracking electronics for rapid (typically 20 min per image), quantitative imaging of nanoscale elastic properties. We describe how such methods not only provide modulus mapping capabilities, but also have enabled us to detect variations in adhesion between a thin film and substrate.

The dependence of the magnetodynamic response of thin permalloy films was measured with a pulsed inductive microwave magnetometer as a function of varying width of the coplanar waveguide center conductor (220to990μm), frequency (0.6to2GHz) and film thickness (25to93nm) to ascertain the role of magnetostatic spin-wave generation in the low-frequency enhancement of the measured decay rate. A component of the decay rate depends on δw, the ratio of film thickness to center conductor width as theoretically predicted. However, there is an anomalous contribution to the frequency dependence of the decay rate exists that cannot be attributed to the generation of spin-waves.

In this study, angle-resolved pulsed inductive microwave magnetometry is used to investigate the symmetry of the dynamic anisotropy of thin Permalloy films. We measured the dynamic anisotropy field as a function of angle between the easy axis and the applied bias field. We found that, in addition to the expected uniaxial anisotropy, there is a rotatable component of anisotropy. This component of the anisotropy is present only during the dynamics measurements and is attributed to surface effects in the thin films. However, the native oxide layer is not the cause of the rotatable anisotropy components in these films.

It has come to our attention that images of static domain patterns in Permalloy using a quadrant-detection scheme were first obtained by Clegg, Heyes, Hill, and Wright in 1991.12 Thus, our claim to have been the first group to image static domains using such a method was incorrect. The description of the instrument and its principle of operation remain correct. The quality of the image presented3 represents an improvement over previously published results using a similar detection scheme, permitting an unambiguous determination of Neel wall polarity within the imaged domain structures.

We studied the difference in postoperative thrombotic complications after major spinal surgery between two commonly used external compression devices. Our 136 subjects were prospectively randomized to receive either thigh-high sequential pneumatic compression wraps or pneumatic foot-compression wraps. All were studied postoperatively with duplex ultrasonography and analyzed for leg swelling, the rate of thrombotic events, and overall subjective patient comfort. The rate of postoperative thrombosis was 1.5%. The one pulmonary embolism was successfully treated with heparin. One other patient had a small asymptomatic thrombus of the saphenous vein. Both subjects wore foot wraps. Subjectively, the devices were rated as being equally comfortable. We believe that external compression for thrombosis prophylaxis after major spinal surgery is effective. The particular device chosen may be driven by other factors such as cost, physician or nursing preference, and ease of application.

Although the normal sagittal profile of the thoracolumbar spine has been described, this has been obtained primarily by using young individuals standing. We sought to describe the sagittal profile of the thoracolumbar spine in an older population in the supine cross-table lateral position compared with that standing. We enrolled 50 volunteers with no history of back pain or spine deformity and 50 matched subjects with mechanical back pain (LBP) only. Lateral radiographs of the thoracolumbar spine (T10-S1) in both standing and cross-table supine positions were obtained. Lordosis from L1 to S1, kyphosis from T10 to L1, and the changes seen moving from the supine position to standing were calculated. There were few differences comparing the two groups in either the standing or cross-table supine position, or when changing positions. Within each group, however, there were small, but significant, differences in the midlumbar and thoracolumbar spine when comparing supine versus standing. Both asymptomatic individuals and those with a history of LBP demonstrated similar small but statistically significant increases in lumbar lordosis and thoracolumbar kyphosis when standing versus supine. The clinical significance of these findings remains to be determined.

Giant magnetoresistance was measured as a function of time and device size for patterned NiFe/Ag multilayerfilms. The sputtered NiFe/Ag multilayers were postannealed at 340 °C for 5 min in order to produce a change in resistivity Δρ/ρ of 5% in a saturating field of 4 kA/m (50 Oe). The microstructure of these films is believed to be discontinuous due to Ag bridging through the NiFe grain boundaries after the anneal. The films were fabricated into rectangular stripes with Au current lead, and then exposed to a magnetic field pulse to measure the time response of the resistance, characterized by a time constant τ, from the relation ΔR(t)=ΔR 0 e −t/τ. An apparatus was developed to produce a magnetic field pulse up to 8 kA/m (100 Oe) with a turn‐on/off time constant of 10 μs. The response of the NiFe/Ag devices saturated quickly with the turn‐on step with a time constant nearly equal to that of the field pulse. The response to the turn‐off step, however, had a time constant of nearly 300 μs. When the field is first applied, the torque on the magnetic moments quickly aligns the magnetization. When the field is shut off, however, the torque due to the field drops to 0, so interacting magnetostatic fields from the grains and thermal energy dominate the relaxation process. The average time constant depends on the device size and the applied current density. Relaxation may be detrimental for using this type of material for read heads where very high data rates are required.

The magnetoresistive (MR) response was measured in Ni‐Fe thin films, representative of the films used in magnetic recording read heads, with sense areas as small as 6×6 μm. For the bulk, central, and edge regions of the film, the MR response was measured as a function of magnitude and angle of a uniform in‐plane applied magnetic field. Measurements were made using a four‐contact technique which included two scanning microprobes and two orthogonal field sources. The microprobes could be scanned with a resolution of 0.1 μm and positioned separately. The field sources produced a maximum field of 24 kA/m (300 Oe) that could be rotated up to ±15°. From the local MR response, the local magnetic behavior was obtained and compared to micromagnetic theory. The bulk MR response was also measured as a function of position on the film of a microfield source used for point‐source excitation. The microfield source was a Fe wire electrochemically etched to a 0.1 μm tip diameter. From these results the local MR sensitivi...

A model of domain wall oscillations under the influence of a bias field step is presented and discussed. This model is based on the relation of the velocity of the wall on its momentum which is computed by minimization of the energy of a cylindrically symmetric twisted domain wall of finite thickness. No adjustable parameters are used. Es wird ein Modell fur Domanenwandschwingungen unter dem Einflus eines Vorspannungsfeldes vorgeschlagen und diskutiert. Dieses Modell beruht auf der Abhangigkeit der Wandgeschwindingkeit von ihrem Impuls, die durch Minimalisierung der Energie einer zylindersymmetrischen verdrehten Domanenwand endlicher Dicke berechnet wird. Es werden keine anpasbaren Parameter benutzt.

Validation and evaluation of the recently released ADVANTG code is presented in the paper. ADVANTG is a hybrid transport code, which combines a deterministic neutron transport code Denovo with MCNP, a well-known Monte Carlo (MC) transport code. ADVANTG was tested on an ICSBEP labyrinth benchmark where neutron fluxes were measured and calculated in a three-section concrete labyrinth for a 252Cf neutron source. The speed-up factors or the increases in relative efficiency of up to 1400 compared to analog MCNP simulations were achieved using the ADVANTG-generated variance reduction parameters. ADVANTG accelerated the calculations in terms of the CPU time and the calculated values were in good agreement with the experimental values. Additionally, it was shown that no bias was introduced by the ADVANTG code, as the mean values obtained by the ADVANTG accelerated calculation are within statistical uncertainties of the analog calculation. The presented work has shown that ADVANTG is a useful tool for use in solving neutron transport problems in geometries featuring labyrinth.

Validation and evaluation of the recently released ADVANTG code, which combines a well-known Monte Carlo (MC) transport code MCNP with a deterministic neutron transport code Denovo, is presented in the paper. The aim of ADVANTG is to automate the process of generating the variance reduction parameters for the fixed source MCNP calculations, which consequently accelerate the simulations in terms of the required CPU time. Reliability and consistent performance of the ADVANTG code were tested on a computationally demanding benchmark, i.e. the skyshine benchmark experiment from the ICSBEP handbook where neutron and photon scattering in the air above an open operating reactor are simulated. The speed-up factors or the increases in relative efficiency of up to 30,000 and 1400 compared to analog MCNP simulations were achieved using the ADVANTG-generated variance reduction parameters for neutrons and photons respectively. As the mean values obtained by the ADVANTG-accelerated simulation sit within the statistical uncertainties of the analog simulation, it was shown that no additional bias is introduced by the ADVANTG code. This article shows that ADVANTG code is a useful and effective tool for use in solving neutral particle transport problems in large geometries featuring skyshine.