Optimizing magnetically shielded solenoids.

An important consideration when designing a magnetostatic cavity for various applications is to maximize the ratio of the volume of field homogeneity to the overall size of the cavity. We report a design of a magnetically shielded solenoid that significantly improves the transverse field gradient averaged over a volume of 1000 cm3 by placing compensation coils around the holes in the mu-metal end caps rather than the conventional design in which the compensation coils are placed on the main solenoid. Our application is polarized 3He-based neutron spin filters, and our goal was to minimize the volume-averaged transverse field gradient, thereby the gradient induced relaxation time, over a 3He cell. For solenoids with end cap holes of different sizes, additional improvements in the field gradient were accomplished by introducing non-identical compensation coils centered around the non-identical holes in the end caps. The improved designs have yielded an overall factor of 7 decrease in the gradient in the solenoid, hence a factor of 50 increase in the gradient induced relaxation time of the 3He polarization. The results from both simulation and experiments for the development of several such solenoids are presented. Whereas our focus is on the development of magnetically shielded solenoids for 3He neutron spin filters, the approach can be applied for other applications demanding a high level of field homogeneity over a large volume.

Characterization and simulation of soft gamma-ray mirrors for their use with spent fuel rods at reprocessing facilities.

The use of a grazing incidence optic to selectively reflect K-shell fluorescence emission and isotope-specific lines from special nuclear materials is a highly desirable nondestructive analysis method for use in reprocessing fuel environments. Preliminary measurements have been performed, and a simulation suite has been developed to give insight into the design of the x ray optics system as a function of the source emission, multilayer coating characteristics, and general experimental configurations. The experimental results are compared to the predictions from our simulation toolkit to illustrate the ray-tracing capability and explore the effect of modified optics in future measurement campaigns.

Local weak ferromagnetism in single-crystalline ferroelectric BiFeO3.

Polarized small-angle neutron scattering studies of single-crystalline multiferroic BiFeO(3) reveal a long-wavelength spin density wave generated by ∼1° spin canting of the spins out of the rotation plane of the antiferromagnetic cycloidal order. This signifies weak ferromagnetism within mesoscopic regions of dimension 0.03 microns along [110], to several microns along [111], confirming a long-standing theoretical prediction. The average local magnetization is 0.06 µ(B)/Fe. Our results provide an indication of the intrinsic macroscopic magnetization to be expected in ferroelectric BiFeO(3) thin films under strain, where the magnetic cycloid is suppressed.

Core-shell magnetic morphology of structurally uniform magnetite nanoparticles.

A new development in small-angle neutron scattering with polarization analysis allows us to directly extract the average spatial distributions of magnetic moments and their correlations with three-dimensional directional sensitivity in any magnetic field. Applied to a collection of spherical magnetite nanoparticles 9.0 nm in diameter, this enhanced method reveals uniformly canted, magnetically active shells in a nominally saturating field of 1.2 T. The shell thickness depends on temperature, and it disappears altogether when the external field is removed, confirming that these canted nanoparticle shells are magnetic, rather than structural, in origin.

Magnetostriction and magnetic heterogeneities in iron-gallium.

Iron-gallium alloys Fe(1-x)Ga(x) exhibit an exceptional increase in magnetostriction with gallium content. We present small-angle neutron scattering investigations on a Fe(0.81)Ga(0.19) single crystal. We uncover heterogeneities with an average spacing of 15 nm and with magnetizations distinct from the matrix. The moments in and around the heterogeneities are observed to reorient with an applied magnetic field or mechanical strain. We discuss the possible roles played by nanoscale magnetic heterogeneities in the mechanism for magnetostriction in this material.

Application of stereolithographic custom models for studying the impact of biofilms and mineral precipitation on fluid flow.

Here we introduce the use of transparent experimental models fabricated by stereolithography for studying the impacts of biomass accumulation, minerals precipitation, and physical configuration of flow paths on liquid flow in fracture apertures. The internal configuration of the models ranged in complexity from simple geometric shapes to those that incorporate replicated surfaces of natural fractures and computationally derived fracture surfaces. High-resolution digital time-lapse imaging was employed to qualitatively observe the migration of colloidal and soluble dyes through the flow models. In this study, a Sphingomonas sp. and Sporosarcina (Bacillus) pasteurii influenced the fluid dynamics by physically altering flow paths. Microbial colonization and calcite deposition enhanced the stagnant regions adjacent to solid boundaries. Microbial growth and calcite precipitation occurred to a greater extent in areas behind the fabricated obstacles and less in high-velocity orifices.

Intensity-weighted phase-derivative statistics.

It is shown that amplitude weighting can improve the accuracy of measurements of the frequency offset of a signal contaminated by multiplicative Gaussian noise. The more general non-Gaussian case is investigated through study of the statistics of a simple phase-screen scattering model. Formulas are derived for the low-order moments of the intensity-weighted phase derivative. Numerical simulation is tested against these results and is used to generate full probability densities that are analytically intractable and to determine the optimum weighting for the non-Gaussian regime of the model. The results are relevant to a variety of remote-sensing and signal-processing problems.

Phase I study of docetaxel with concomitant thoracic radiation therapy.

PURPOSE: The taxanes have demonstrated activity as radiation sensitizers in preclinical studies. This study was designed to determine the maximum-tolerated dose (MTD), optimal schedule, and toxicities of docetaxel in combination with concomitant standard chest radiotherapy. PATIENTS AND METHODS: Twenty-nine patients with advanced non-small-cell lung or esophageal cancer enrolled in this phase I study to evaluate escalating docetaxel doses at three schedules. Docetaxel was administered as two 21-day cycles at doses of 40, 60, and 75 mg/m2 per cycle. Docetaxel administration schedules were as follows: schedule A, once every 3 weeks; schedule B, 2 of 3 weeks; or schedule C, weekly. Six weeks of concomitant standard chest radiotherapy in 1.8- to 2.0-Gy daily fractions was delivered to 60 Gy total. RESULTS: Dose-limiting esophagitis and neutropenia were encountered with schedules A and B at docetaxel doses of 60 mg/m2 per cycle. The docetaxel MTD for schedules A and B was 40 mg/m2 per cycle. Dose-limiting esophagitis was also observed with schedule C; however, there was no neutropenia. For schedule C, we identified the MTD as 60 mg/m2 per cycle (20 mg/m2/wk). Other toxicities encountered included thrombocytopenia, hypersensitivity reaction, and pulmonary infiltrates (fatal in two patients). Late toxicity of esophageal stricture occurred in five patients. CONCLUSION: Esophagitis and neutropenia are the dose-limiting toxicities of docetaxel administered with concomitant chest radiotherapy. Weekly administration of docetaxel allows for the highest total docetaxel dose during chest radiotherapy. We identified the recommended phase II docetaxel dose as 20 mg/m2 administered weekly with concomitant chest radiotherapy for 6 weeks.

Restriction fragment length polymorphism analysis of zoo animals using HaeIII and four single-locus probes.

Using HaeIII as the restriction endonuclease, restriction fragment length polymorphism analysis of dried blood samples from various animals was conducted. Single-locus probes D2S44, D10S28, D1S7, and D4S139, as well as monomorphic probe D7Z2, were used to examine for banding patterns. If bands were present, the samples were further examined for heterogeneity (whether single or multiple bands were observed) and polymorphism (whether variation in band location was shown between the animals studied within a species). Blood samples from animals, including primates, were obtained from Miami Metrozoo, Miami, Florida. Some of the animals were non-related individuals while others were related. Banding patterns were observed in colobus' for D2S44, D1S7, and D4S139; owl monkeys for D2S44; gorillas for D2S44 and D4S139; gibbons for D2S44 and D4S139; siamangs for D2S44, talapoins for DiS7; cranes for D1S7; and otters for D1S7. Based upon these, all of the animals for which a conclusion could be drawn appeared to be homozygous and monomorphic (exhibited only an invariant single band) for the loci examined except colobus' for D4S139, gorillas for D4S139, cranes for D1S7, and otters for D1S7.

Direct imaging of nonsolar planets with infrared telescopes using apodized coronagraphs.

This research examines the use of modified Lyot coronagraphs with monolithic and segmented infrared telescopic systems for imaging nonsolar planets. These systems are investigated with the aim of reducing the effects of stellar diffracted energy on the planet image in the final image plane. A square telescope objective is best for this purpose. The associated coronagraph is composed of a cross-shaped apodizer in the first focal plane and either a square Lyot stop or circular corner Lyot stops in the corners of the pupil plane. We examine the consequences of segmenting the aperture and the effects of various segment spacings and random piston and tilt errors of the individual segments. A system to correct for the misalignments is proposed.

Peer relations of hearing-impaired adolescents.

Compared peer relations of hearing-impaired adolescents (n = 35) with those of hearing adolescents (n = 35) based on reports from mothers, fathers, and adolescents. Dependent measures included the emotional bonding, aggression, and social maturity subscales of the Missouri Peer Relations Inventory, the socialized aggression subscale from the Revised Behavior Problem Checklist and the activities and social subscales of the Child Behavior Checklist. Analyses showed that parents of hearing-impaired youths rated their adolescents' friendships as relatively high in aggression, but hearing-impaired adolescents rated their behavior with friends as relatively low in aggression. These findings were interpreted in light of recent research regarding the cognitive biases of aggressive hearing children. Mothers of hearing-impaired youths also rated their adolescents' friendships as lower in emotional bonding than did mothers of hearing adolescents.

The adaptation of hearing parents of hearing-impaired youths.

This study evaluated the emotional and marital adjustment of hearing parents of hearing-impaired youths. Participants included mothers and fathers of hearing-impaired youths and mothers and fathers of hearing youths. In contrast with expectations based on clinical impressions reported in the literature, parents of hearing-impaired youths reported less symptomatology than did parents of hearing youths, and there were no differences in the marital satisfaction of parents in intact families. Moreover, parental adjustment was not associated with the duration of time since the child was diagnosed as hearing impaired. In addition, hierarchical multiple regression analyses revealed that family cohesion was associated with low maternal symptomatology and high marital satisfaction for both spouses. For mothers, low symptomatology was associated with low stress and female gender of child; high marital satisfaction also was linked with a less severe degree of hearing loss in the youth.

Family functioning and the social adaptation of hearing-impaired youths.

This study examined the associations between important aspects of family functioning and the adjustment of hearing-impaired youths. Participants were 75 hearing-impaired youths and their hearing parents. The dependent variables were mothers' and fathers' ratings of child behavior problems and social competence. Independent variables included parental symptomatology, parental ratings of family stress, and family members' perceptions of family cohesion and family adaptability. Demographic characteristics and the youth's degree of hearing loss and mode of communication were used as control variables. Results from multiple regression analyses showed that parental ratings of the youths' behavior problems were linked with parental symptomatology, and that maternal ratings of the youths' behavior problems were associated with low family adaptability. Parental ratings of the youths' social competence were predicted by family stress. Overall, key aspects of family functioning accounted for considerably more variance than did the control variables. The methodological and conceptual implications of the findings are discussed.

Long-term survival of patients with intermediate and high grade lymphoma treated with COMLA/ABP.

Between September 1983 and April 1985, 15 patients with previously untreated intermediate and high grade lymphoma were treated with COMLA/ABP (cyclophosphamide, vincristine, cytarabine, methotrexate, leucovorin, adriamycin, bleomycin, prednisone). There were nine males and six females; age ranged between 36 and 77 years (median, 58). Histologic diagnoses included five patients with diffuse large cell, six patients with immunoblastic, three patients with composite, and one patient with follicular large cell with diffuse areas. Following therapy, 10 patients (67%; 95% confidence interval (Cl), 43-91%) achieved a complete remission (CR) including five of six patients with immunoblastic; three patients (20%) had a partial remission, and two patients (14%) had no response. Toxicity was acceptable. After a minimum follow up of 4 years, there has been only one relapse which occurred 7 months after CR. The 4-year survival for all 15 patients is 65% (95% Cl, 40-89%). The COMLA/APB program produced a high rate of complete and durable remissions especially among patients with immunoblastic lymphoma.

Sidelobe reduction via multiaperture optical systems.

The impulse responses of multiaperture optical systems can generate large sidelobe irradiances. The purpose of this research was to design multiaperture systems with impulse responses that exhibit sidelobe irradiances less than that of the Airy pattern and central lobe widths no greater than that of a single large aperture of an equivalent diameter. Multiaperture systems composed of 19, 37, 61, and 91 apertures satisfy these performance criteria. However, the amount of energy in the central lobes of the multiaperture systems was less than that of a single large aperture.

Relationships among plasma cortisol, adrenocorticotrophin, and severity of injury in recently injured patients.

When samples were taken within 2 hr of accidental injury, plasma cortisol levels increased with injury severity score (ISS) in patients with minor and moderate injuries (ISS, 1-12) but decreased at higher ISS. Radioimmunoassay of adrenocorticotrophin (ACTH) showed very variable plasma concentrations at all ISS ranges. Like cortisol, ACTH increased with ISS up to a score of about 13, but it thereafter plateaued, and in patients with severe injuries plasma cortisol fell in relation to ACTH as well as in absolute terms. This suggested that although ACTH secretion was generally far from maximal the relatively low cortisol concentrations in the most severely injured were at least partly due to a poor response of the adrenal cortex to ACTH. In patients who presented late (more than 2 hr after injury) plasma cortisol levels were more variable and more strongly related to ACTH than at shorter times after injury. The variability of cortisol also increased with age. Patients with severe head injuries had cortisol and ACTH concentrations similar to those without head injuries but with a similar ISS from injuries in other parts of the body.