Temporal variation in the new proton belt created in March 1991 observed using the CREAM & CREDO experiments.

The Cosmic Radiation Environment & Activation Monitor (CREAM) was carried in high inclination (57.1 degrees) orbits on Shuttle missions STS-48 in September 1991 (altitude 570 km) and STS-53 (altitude 325 to 385 km) in December 1992. On both occasions the instrument observed an excess of counts due to protons of greater than 30 MeV in energy in the region off of South Africa where field lines of L=2.5 intersect low earth orbit. Meanwhile the Cosmic Radiation Environment and Dosimetry Experiment (CREDO) carried to 840 km, 98.7 degrees orbit on UOSAT-3 has continued to sample the high field portions of the L-shells around L = 2.5 from April 1990 until the present time. When careful subtraction of cosmic-ray contributions is made it can be seen that the March 91 enhancement persisted for approximately 8 months and explains the STS-48 observation. There would appear to have been a further increase produced by the 31 October 1992 flare event and seen by STS-53.

Secondary radiation environments in heavy space vehicles and instruments.

Secondary radiations produced by the interactions of primary cosmic rays and trapped protons with spacecraft materials and detectors provides an important, and sometimes dominant, radiation environment for sensitive scientific instruments and biological systems. In this paper the success of a number of calculations in predicting a variety of effects will be examined. The calculation techniques include Monte Carlo transport codes and semi-empirical fragmentation calculations. Observations are based on flights of the Cosmic Radiation Environment and Activation Monitor at a number of inclinations and altitudes on Space Shuttle. The Shuttle experiments included an active cosmic-ray detector as well as metal activation foils and passive detector crystals of sodium iodide which were counted for induced radioactivity soon after return to earth. Results show that cosmic-ray secondaries increase the fluxes of particles of linear energy transfer less than 200 MeV/(gm cm-2), while the activation of the crystals is enhanced by about a factor of three due to secondary neutrons. Detailed spectra of induced radioactivity resulting from spallation products have been obtained. More than a hundred significant radioactive nuclides are included in the calculation and overall close agreement with the observations is obtained.

Calculations and observations of solar particle enhancements to the radiation environment at aircraft altitudes.

Solar particle events can give greatly enhanced radiation at aircraft altitudes, but are both difficult to predict and to calculate retrospectively. This enhanced radiation can give significant dose to aircrew and greatly increase the rate of single event effects in avionics. Validation of calculations is required but only very few events have been measured in flight. The CREAM detector on Concorde detected the event of 29 September 1989 and also four periods of enhancement during the events of 19-24 October 1989. Instantaneous rates were enhanced by up to a factor ten compared with quiet-time cosmic rays, while flight-averages were enhanced by up to a factor six. Calculations are described for increases in radiation at aircraft altitudes using solar particle spectra in conjunction with Monte Carlo radiation transport codes. In order to obtain solar particle spectra with sufficient accuracy over the required energy range it is necessary to combine space data with measurements from a wide range of geomagnetically dispersed, ground-level neutron monitors. Such spectra have been obtained for 29 September 1989 and 24 October 1989 and these are used to calculate enhancements that are compared with the data from CREAM on Concorde. The effect of cut-off rigidity suppression by geomagnetic activity is shown to be significant. For the largest event on record on 23 February 1956, there are no space data but there are data from a number of ground-level cosmic-ray detectors. Predictions for all events show very steep dependencies on both latitude and altitude. At high latitude and altitude (17 km) calculated increases with respect to cosmic rays are a factor 70 and 500 respectively for 29 September 1989 and 23 February 1956. The levels of radiation for high latitude, subsonic routes are calculated, using London to Los Angeles as an example, and can exceed 1 mSv, which is significantly higher than for Concorde routes from Europe to New York. The sensitivity of the calculations to spectral fitting, geomagnetic activity and other assumptions demonstrates the requirement for widespread carriage of radiation monitors on aircraft.

The low earth orbit environment observed using CREAM and CREDO.

The Cosmic Radiation Environment and Dosimetry experiment (CREDO) has been operational on board the Advanced Photovoltaics & Electronics Experiment Spacecraft since August 1994. Extensive measurements of cosmic ray linear energy transfer spectra (using data to January 1996) and total dose (using data to November 1994) have been made, and compared with predictions of standard models. Detailed consideration of spacecraft shielding effects have been made. Predictions are shown to overestimate the measured linear energy transfer spectra. The CREAM experiment was flown on STS-63 in the SpaceHab module. Results show penetration of high energy electrons into the SpaceHab module.

Gamma-ray measurements from the space shuttle during a solar flare.

An X2/2B level solar flare occurred on 12 August, 1989, during the last day of the flight of the Space Shuttle Columbia (STS-28). Detectors on the GOES 7 satellite observed increased X-ray fluxes at approximately 1400 GMT and a solar particle event (SPE) at approximately 1600 GMT. Measurements with the bismuth germanate (BGO) detector of the Shuttle Activation Monitor (SAM) experiment on STS-28 showed factors of two to three increases in count rates at high latitudes comparable to those seen during South Atlantic Anomaly (SAA) passages beginning at about 1100 GMT. That increased activity was observed at both north and south high latitudes in the 57 degrees, 300 kilometer orbit and continued until the detector was turned off at 1800 GMT. Measurements made earlier in the flight over the same geographic coordinates did not produce the same levels of activity. This increase in activity may not be entirely accounted for by observed geomagnetic phenomena which were not related to the solar flare.

Effects of increased shielding on gamma-radiation levels within spacecraft.

The Shuttle Activation Monitor (SAM) experiment was flown on the Space Shuttle Columbia (STS-28) from 8-13 August, 1989 in a 57 degrees, 300 km orbit. One objective of the SAM experiment was to determine the relative effect of different amounts of shielding on the gamma-ray backgrounds measured with similarly configured sodium iodide (NaI) and bismuth germante (BGO) detectors. To achieve this objective twenty-four hours of data were taken with each detector in the middeck of the Shuttle on the ceiling of the airlock (a high-shielding location) as well as on the sleep station wall (a low-shielding location). For the cosmic-ray induced background the results indicate an increased overall count rate in the 0.2 to 10 MeV energy range at the more highly shielded location, while in regions of trapped radiation the low shielding configuration gives higher rates at the low energy end of the spectrum.

Observations and predictions of secondary neutrons on Space Shuttle and aircraft.

The Cosmic Radiation Effects and Activation Monitor has flown on six Shuttle flights between September 1991 and February 1995 covering the full range of inclinations as well as altitudes between 220 and 570 km, while a version has flown at supersonic altitudes on Concorde between 1988 and 1992 and at subsonic altitudes on a SAS Boeing 767 between May and August 1993. The Shuttle flights have included passive packages in addition to the active cosmic ray monitor which comprises an array of pin diodes. These are positioned at a number of locations to investigate the influence of shielding and local materials. Use of both metal activation foils and scintillator crystals enables neutron fluences to be inferred from the induced radioactivity which is observed on return to Earth. Supporting radiation transport calculations are performed to predict secondary neutron spectra and the energy deposition due to nuclear reactions in silicon pin diodes and the induced radioactivity in the various scintillator crystals. The wide variety of orbital and atmospheric locations enables investigation of the influence of shielding on cosmic ray, trapped proton and solar flare proton spectra.

Updated measurements from CREAM & CREDO & implications for environment & shielding models.

Flight data obtained between 1995 and 1997 from the Cosmic Radiation Environment Monitors CREAM & CREDO carried on UoSat-3, Space Shuttle, STRV-1a (Space Technology Research Vehicle) and APEX (Advanced Photovoltaic and Electronics Experiment Spacecraft) have been added to the dataset affording coverage since 1990. The modulation of cosmic rays and evolution of the South Atlantic Anomaly are observed, the former comprising a factor three increase at high latitudes and the latter a general increase accompanied by a westward drift. Comparison of particle fluxes and linear energy transfer spectra is made with improved environment & radiation transport calculations which account for shield distributions and secondary particles. While there is an encouraging convergence between predictions and observations, significant improvements are still required, particularly in the treatrnent of locally produced secondary particles.

Implications for space radiation environment models from CREAM & CREDO measurements over half a solar cycle.

Flight data obtained between 1990 and 1997 from the Cosmic Radiation Environment Monitors CREAM & CREDO carried on UoSAT-3, Space Shuttle, STRV-1a (Space Technology Research Vehicle) and APEX (Advanced Photovoltaic and Electronics Experiment Spacecraft) provide coverage over half a solar cycle. The modulation of cosmic rays and evolution of the South Atlantic Anomaly are observed, the former comprising a factor of three increase at high latitudes and the latter a general increase accompanied by a north-westward drift. Comparison of particle fluxes and linear energy transfer (LET) spectra is made with improved environment & radiation transport calculations which account for shield distributions and secondary particles. While there is an encouraging convergence between predictions and observations, significant improvements are still required, particularly in the treatment of locally produced secondary particles. Solar-particle events during this time period have LET spectra significantly below the October 1989 event which has been proposed as a worst case model.

Filled versus empty intervals in prospective hypnotic time estimation with a real-simulator design.

While interest in hypnotic time perception dates back to the 19th century (St. Jean, 1989) only recently have researchers focused on hypnosis and time estimation under more controlled conditions. Following the work of Jasinski (1986) and Mozenter and Kurtz (1992) we predicted a 2-way interaction between Group (high hypnotizable, low hypnotizable, and simulator) and Condition (waking, hypnotized) across 3 time intervals (30, 60, and 120 seconds). It was further hypothesized that "filled" intervals (with white noise) would be perceived as longer than "empty" intervals across all conditions. Sixty-two undergraduates were screened on the Stanford Hypnotic Susceptibility Scale: Form C and verbally estimated time intervals of 30, 60, and 120 seconds, 5 times each, both while in a waking and a hypnotic condition. Support was found for the predicted 2-way interaction for women only. High hypnotizable women showed a significant increase in overestimation from the waking to hypnosis condition, men did not. The predicted difference between "filled" versus "empty" intervals was not found.

Further phenotypic delineation of subtelomeric (terminal) 4q deletion with emphasis on intracranial and reproductive anatomy.

OBJECTIVE: To describe selected morphological and developmental features associated with subtelomeric deletion at chromosome 4q. MATERIALS AND METHODS: A 21-year old female was brought for gynecologic evaluation of menorrhagia. High-resolution metaphase karyotype and subtelomere fluorescent in-situ hybridization (FISH) analysis were used for genotype determination. Pelvic anatomy was characterized via CT and laparoscopy; MR and CT were used for intracranial imaging. RESULTS: A de novo deletion [46,XX del(4)(q32)] was identified cytogenetically and confirmed as a terminal loss via subtelomere FISH. Hand/foot malformation characteristic of deletion at this segment was present. Pelvic CT and laparoscopy revealed normal uterine anatomy. Fallopian tubes appeared grossly unremarkable, and a right ovarian cyst was excised without difficulty. Bilateral broad ligament fibroadipose nodularities were noted adjacent to the uterus between round ligament and fallopian tube. Neurological exam revealed no focal defects, although brain MR identified an abnormal signal intensity at the inferior margin of the globus pallidus, consistent with old lacunar infarct and gliosis. Developmental delay was supported by an observed level of general intellectual function estimated at age seven. CONCLUSION: Terminal deletion of the long arm of chromosome 4 is a rare genetic event associated with a distinctive phenotype dependent on the size of the deletion. Chromosomal losses that span the 4q32 band include mental retardation and mild craniofacial anomalies. Here, further characterization of this disorder is offered including precise quantification of the DNA loss, information on brain morphology and pelvic anatomy. Additional studies will be required to characterize the full developmental and physiologic implications of this unusual genetic disorder.

Upsetting social interactions and distress among Alzheimer's disease family care-givers: a replication and extension.

Although several studies have suggested that negative aspects of relationships have a greater impact on mood than positive elements, the individuals in these studies have been victims of life crises. To assess the generality of these findings, social support and mood data were collected from two well-matched groups that differed with respect to the presence of a chronic stressor in their lives. The 34 family care-givers for Alzheimer's disease victims and 34 comparison persons (non-care-givers) did not differ in the frequency of contacts, the closeness of their relationships, or ratings of the helpfulness or upset associated with the relationships. However, while upset accounted for a significant portion of the variance in care-givers' depressive symptoms in regression equations, neither upset nor helpfulness was significantly related to mood in non-care-givers. Care-givers whose relatives had more symptomatic Alzheimer's disease behaviors were more distressed and described their relationships with others as more upsetting. Implications for interventions and for the contextual importance of upsetting or negative support are discussed.

Chronic stress and immunity in family caregivers of Alzheimer's disease victims.

Although acute stress has been associated with transient immunosuppression, little is known about the immunologic consequences of chronic stress in humans. In order to investigate possible health-related consequences of a long-term stressor, we obtained blood samples for immunologic and nutritional analyses and psychologic data from 34 family caregivers of Alzheimer's disease (AD) victims and 34 sociodemographically matched comparison subjects. Family caregivers for AD victims were more distressed than comparison subjects without similar responsibilities. Greater impairment in the AD victim was associated with greater distress and loneliness in caregivers. Caregivers had significantly lower percentages of total T lymphocytes and helper T lymphocytes than did comparison subjects, as well as significantly lower helper-suppressor cell ratios; caregivers also had significantly higher antibody titers to Epstein-Barr virus than did comparison subjects, presumably reflecting poorer cellular immune system control of the latent virus in caregivers. The percentages of natural killer cells and suppressor T lymphocytes did not differ significantly. These data suggest that chronically stressed AD family caregivers do not show immunologic or psychologic adaptation to the level of their well-matched age peers.