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Measurements from NASA's Van Allen Probes have transformed our understanding of the dynamics of Earth's geomagnetically-trapped, charged particle radiation. The Van Allen Probes were equipped with the Magnetic Electron Ion Spectrometers (MagEIS) that measured energetic and relativistic electrons, along with energetic ions, in the radiation belts. Accurate and routine measurement of these particles was of fundamental importance towards achieving the scientific goals of the mission. We provide a comprehensive review of the MagEIS suite's on-orbit performance, operation, and data products, along with a summary of scientific results. The purpose of this review is to serve as a complement to the MagEIS instrument paper, which was largely completed before flight and thus focused on pre-flight design and performance characteristics. As is the case with all space-borne instrumentation, the anticipated sensor performance was found to be different once on orbit. Our intention is to provide sufficient detail on the MagEIS instruments so that future generations of researchers can understand the subtleties of the sensors, profit from these unique measurements, and continue to unlock the mysteries of the near-Earth space radiation environment. Supplementary Information The online version contains supplementary material available at 10.1007/s11214-021-00855-2.

Microbursts are an impulsive increase of electrons from the radiation belts into the atmosphere and have been directly observed in low Earth orbit and the upper atmosphere. Prior work has estimated that microbursts are capable of rapidly depleting the radiation belt electrons on the order of a day; hence, their role to radiation belt electron losses must be considered. Losses due to microbursts are not well constrained, and more work is necessary to accurately quantify their contribution as a loss process. To address this question, we present a statistical study of >35 keV microburst sizes using the pair of AeroCube‐6 CubeSats. The microburst size distribution in low Earth orbit and the magnetic equator was derived using both spacecraft. In low Earth orbit, the majority of microbursts were observed, while the AeroCube‐6 separation was less than a few tens of kilometers, mostly in latitude. To account for the statistical effects of random microburst locations and sizes, Monte Carlo and analytic models were developed to test hypothesized microburst size distributions. A family of microburst size distributions were tested, and a Markov chain Monte Carlo sampler was used to estimate the optimal distribution of model parameters. Finally, a majority of observed microbursts map to sizes less than 200 km at the magnetic equator. Since microbursts are widely believed to be generated by scattering of radiation belt electrons by whistler mode waves, the observed microburst size distribution was compared to whistler mode chorus size distributions derived in prior literature., Key Points The dual AeroCube‐6 CubeSats simultaneously observed >35 keV microbursts at a variety of spatial separations ranging from 2 to 100 kmIn low Earth orbit the majority of microbursts have a size on the order of a few tens of kmMapped to the magnetic equator, the majority of microbursts are less than 200 km in size, corresponding to the size of chorus wave packets

This paper describes version 1.5 of the AE9/AP9 family of space radiation climatology models. The most significant update is the inclusion of new data sets that change the flux maps. These new data include measurements from Van Allen Probes, Azur, and the HiLET sensor on the TWINS-2 spacecraft. In recognition of international contributions to the models, we introduce the IRENE nomenclature for International Radiation Environment Near Earth.

This paper describes a framework for incorporating linear radiation effects into the statistical machinery of the AE9/AP9 radiation climatology model software via “kernel” files. Users can provide their own kernels without modification of the software. Kernels can be applied to a variety of radiation effects such as proton single-event effect rate, internal charging current, ionizing dose, and nonionizing dose. Kernels can be generated for custom shielding geometry and materials and for custom parts or material susceptibilities.

The Community Coordinated Modeling Center has been leading community‐wide space science and space weather model validation projects for many years. These efforts have been broadened and extended via the newly launched International Forum for Space Weather Modeling Capabilities Assessment (https://ccmc.gsfc.nasa.gov/assessment/). Its objective is to track space weather models' progress and performance over time, a capability that is critically needed in space weather operations and different user communities in general. The Space Radiation and Plasma Effects Working Team of the aforementioned International Forum works on one of the many focused evaluation topics and deals with five different subtopics (https://ccmc.gsfc.nasa.gov/assessment/topics/radiation-all.php) and varieties of particle populations: Surface Charging from tens of eV to 50‐keV electrons and internal charging due to energetic electrons from hundreds keV to several MeVs. Single‐event effects from solar energetic particles and galactic cosmic rays (several MeV to TeV), total dose due to accumulation of doses from electrons (>100 keV) and protons (>1 MeV) in a broad energy range, and radiation effects from solar energetic particles and galactic cosmic rays at aviation altitudes. A unique aspect of the Space Radiation and Plasma Effects focus area is that it bridges the space environments, engineering, and user communities. The intent of the paper is to provide an overview of the current status and to suggest a guide for how to best validate space environment models for operational/engineering use, which includes selection of essential space environment and effect quantities and appropriate metrics., Key Points Providing an overview of the current status and proposing a guide for how to best validate space environment models for operational useTwo types of physical quantities for both science and engineering purposes have been identifiedProper metrics are needed for evaluating space environment models for different application purposes

Participants of the 2017 European Space Weather Week in Ostend, Belgium, discussed the stakeholder requirements for space weather related models. It was emphasized that stakeholders show an increased interest in space weather related models. Participants of the meeting discussed particular prediction indicators that can provide first order estimates of the impact of space weather on engineering systems.

We describe an automated computer algorithm designed to remove background contamination from the Van Allen Probes Magnetic Electron Ion Spectrometer (MagEIS) electron flux measurements. We provide a detailed description of the algorithm with illustrative examples from on-orbit data. We find two primary sources of background contamination in the MagEIS electron data: inner zone protons and bremsstrahlung X-rays generated by energetic electrons interacting with the spacecraft material. Bremsstrahlung X-rays primarily produce contamination in the lower energy MagEIS electron channels (∼30–500 keV) and in regions of geospace where multi-MeV electrons are present. Inner zone protons produce contamination in all MagEIS energy channels at roughly L < 2.5. The background-corrected MagEIS electron data produce a more accurate measurement of the electron radiation belts, as most earlier measurements suffer from unquantifiable and uncorrectable contamination in this harsh region of the near-Earth space environment. These background-corrected data will also be useful for spacecraft engineering purposes, providing ground truth for the near-Earth electron environment and informing the next generation of spacecraft design models (e.g., AE9).

We describe a method for using drift echo signatures in on-orbit data to resolve discrepancies between different measurements of particle flux. The drift period has a well-defined energy dependence, which gives rise to time dispersion of the echoes. The dispersion can then be used to determine the effective energy for one or more channels given each channel's drift period and the known energy for a reference channel. We demonstrate this technique on multiple instruments from the Van Allen Probes mission. Drift echoes are only easily observed at high energies (100 s keV to multiple MeV), where several drift periods occur before the observing satellite has moved on or the global magnetic conditions have changed. We describe a first-order correction for spacecraft motion. The drift echo technique has provided a significant clue in resolving substantial flux discrepancies between two instruments measuring fluxes near 2 MeV.

Population-based evidence on second cancer risk following autologous haematopoietic SCT (HCT) is lacking. We quantified second cancer risk for a national, population-based cohort of adult Australians receiving autologous HCT for cancer and notified to the Australasian Bone Marrow Transplant Recipient Registry 1992-2007 (n=7765). Cancer diagnoses and deaths were ascertained by linkage with the Australian Cancer Database and National Death Index. Standardized incidence ratios (SIRs) were calculated and Cox regression models were used to estimate within-cohort risk factors treating death as a competing risk. During a median 2.5 years follow-up, second cancer risk was modestly increased compared with the general population (SIR 1.4, 95% confidence interval 1.2-1.6); significantly elevated risk was also observed for AML/myelodysplastic syndrome (SIR=20.6), melanoma (SIR=2.6) and non-Hodgkin lymphoma (SIR=3.3). Recipients at elevated risk of any second cancer included males, and those transplanted at a younger age, in an earlier HCT era, or for lymphoma or testicular cancer. Male sex, older age (>45 years) and history of relapse after HCT predicted melanoma risk. Transplantation for Hodgkin lymphoma and older age were associated with lung cancer risk. Second malignancies are an important late effect and these results inform and emphasize the need for cancer surveillance in autologous HCT survivors.

The radiation belts and plasma in the Earth’s magnetosphere pose hazards to satellite systems which restrict design and orbit options with a resultant impact on mission performance and cost. For decades the standard space environment specification used for spacecraft design has been provided by the NASA AE8 and AP8 trapped radiation belt models. There are well-known limitations on their performance, however, and the need for a new trapped radiation and plasma model has been recognized by the engineering community for some time. To address this challenge a new set of models, denoted AE9/AP9/SPM, for energetic electrons, energetic protons and space plasma has been developed. The new models offer significant improvements including more detailed spatial resolution and the quantification of uncertainty due to both space weather and instrument errors. Fundamental to the model design, construction and operation are a number of new data sets and a novel statistical approach which captures first order temporal and spatial correlations allowing for the Monte-Carlo estimation of flux thresholds for user-specified percentile levels (e.g., 50th and 95th) over the course of the mission. An overview of the model architecture, data reduction methods, statistics algorithms, user application and initial validation is presented in this paper.

Osteochondral defects of the lateral trochlear ridge of the distal femur were identified in 15 joints of 10 horses. Lesions were bilateral in five horses and unilateral in five horses. Thirteen of these 15 defects were treated by curettage through a craniolateral femoropatellar arthrotomy. Subcutaneous seroma formation and partial skin dehiscence occurred in nine stifles. Lameness attributable to the stifle joint was no longer apparent at 6 and 12 months after surgery. The normal subchondral bony contour of the lateral trochlear ridge was altered in all joints after surgery. The subchondral bone was uniformly increased in density in all joints, and six lateral trochlear ridges had small focal radiolucent regions within the subchondral bone, which suggested that complete removal of the original lesion had not been achieved. Healing of the surgical site between 2 weeks and 14 months was evaluated in four joints. Granulation tissue from mesenchymal elements in subchondral marrow spaces gradually filled the defects with fibrocartilage.

Effects of the South Atlantic Anomaly (SAA) on spacecraft in low Earth orbit (LEO) are well known and documented. The SAA exposes spacecraft in LEO to high dose of ionizing radiation as well as higher than normal rates of Single Event Upsets (SEU) and Single Event Latch-ups (SEL). CubeSats, spacecraft built around 10 x 10 x 10 cm cubes, are even more susceptible to SEUs and SELs due to the use of commercial off-the-shelf components for electronics and payload instrumentation. Examination of the SAA using both data from the Defense Meteorological Satellite Program (DMSP) and a new set of models for the flux of particles is presented. The models, AE9, AP9, and SPM for energetic electrons, energetic protons and space plasma, were developed for use in space system design. These models introduce databased statistical constraints on the uncertainties from measurements and climatological variability. Discussion of the models’ capabilities and limitations with regard to LEO CubeSat design is presented.

The influence of compression and shear loads on the strength of composite laminates with z-pins is evaluated parametrically using a 2D Finite Element Code (FLASH) based on Cosserat couple stress theory. Meshes were generated for three unique combinations of z-pin diameter and density. A laminated plate theory analysis was performed on several layups to determine the bi-axial stresses in the zero degree plies. These stresses, in turn, were used to determine the magnitude of the relative load steps prescribed in the FLASH analyses. Results indicated that increasing pin density was more detrimental to in-plane compression strength than increasing pin diameter. Compression strengths of lamina without z-pins agreed well with a closed form expression derived by Budiansky and Fleck. FLASH results for lamina with z-pins were consistent with the closed form results, and FLASH results without z-pins, if the initial fiber waviness due to z-pin insertion was added to the fiber waviness in the material to yield a total misalignment. Addition of 10% shear to the compression loading significantly reduced the lamina strength compared to pure compression loading. Addition of 50% shear to the compression indicated shear yielding rather than kink band formation as the likely failure mode. Two different stiffener reinforced skin configurations with z-pins, one quasi-isotropic and one orthotropic, were also analyzed. Six unique loading cases ranging from pure compression to compression plus 50% shear were analyzed assuming material fiber waviness misalignment angles of 0, 1, and 2 degrees. Compression strength decreased with increased shear loading for both configurations, with the quasi-isotropic configuration yielding lower strengths than the orthotropic configuration.

The relative sensitivity of radiography, computed tomography, and magnetic resonance imaging for detecting palmar process fractures of the distal phalanx in foals was determined and the imaging findings were compared with histomorphologic evaluations of the palmar processes. Compared to radiography, computed tomography and magnetic resonance imaging did not improve the sensitivity for detection of palmar process fractures. Statistical agreement for palmar process fracture diagnosis was excellent among the three imaging modalities. Histomorphologic evaluations were more sensitive for diagnosis of palmar process fracture than any of the imaging modalities. Three-dimensional image reconstructions and volume measurements of distal phalanges and palmar process fracture fragments from computed tomography studies provided more complete anatomical information than radiography. Magnetic resonance imaging confirmed that the deep digital flexor tendon insertion on the distal phalanx is immediately axial to the site where palmar process fractures occur, and differentiated cartilage, bone, and soft tissue structures of the hoof.

OBJECTIVE To estimate the likelihood of poor surgical results being explained by chance rather than under-performance. METHODS The 30-day mortality rates after radical cystectomy for bladder cancer were analysed theoretically. Surgical competence was defined as a mortality rate of 4%, excellence as 2% and under-performance as 8%, 12%, 20% or 40%. Four scenarios were explored for surgeons of different competence: first, the sample size required to show that a given level of under-performance is very unlikely to be due to chance; second, the likelihood of two or more consecutive deaths in a series of cases; third, the likelihood of clustering of deaths, defined as two deaths in five or in 10 cases; and last, the likelihood of outstanding surgical results (i.e. no deaths) being achieved in small cohorts by surgeons of differing competence. RESULTS For surgeons with a mortality rate of 8%, 12%, 20% or 40%, the sample sizes needed to prove under-performance are 211, 65, 21 and seven, respectively. For consecutive deaths, 0.4% of excellent, 1.4% of competent and 21% of surgeons with a mortality rate of 12% will experience two or more consecutive deaths in the next 10 cases. For clustered deaths, 1% of excellent, 5% of competent and 23% of seriously under-performing surgeons (mortality rates ≥ 12%) will experience two deaths in their next 10 cases. Lastly, for the likelihood of outstanding results, only 3.6% of surgeons with an 8% mortality rate and < 1% of surgeons with a mortality rate ≥ 12% will experience no deaths over 40 consecutive cases. CONCLUSIONS Very large cohorts are needed to confirm even significant under-performance. Consecutive deaths are very unlikely events for competent surgeons. Clustered deaths (two deaths in 10 cases) are very unlikely events for excellent surgeons but plausible for competent ones. Analysis of consecutive/clustered deaths is limited by low statistical sensitivity; only up to a quarter of seriously under-performing surgeons are identified. No deaths in 40 consecutive cases implies competence.

Small sub-component specimens consisting of solid laminates at the ends that transition to X-cor® truss sandwich in the center, were tested in a combination of three point bending, uni-axial tension, and combined tension and bending. The failure process in the transition region was documented for each loading using digital video and high-resolution cameras. For the three-point bending tests, most of the deformation occurred in the solid laminate regions on either end of the specimen. Some pin debonding from the skin of the X-cor® truss sandwich was observed in the transition region and was accompanied by audible “pings” throughout the loading. Tension loaded specimens failed in the sandwich skin in the middle of the gage length, accompanied by separation of the sandwich core from the back skin and by delamination between the top skin and bottom skin at the transition region. The pinging associated with pin debonding occurred as the load was increased. However, the frequency of the pinging exceeded any visual observations of pin debonding in the video of the transition region. For specimens tested in combined tension and bending, the greatest amount of pinging occurred during initial application of the axial load. High-resolution images in the transition region indicated that the pinging corresponded to pins debonding and buckling due to the through-thickness Poisson contraction of the specimen. This buckling continued to a much smaller extent as the transverse load was applied.

The influence of two-dimensional finite element modeling assumptions on the debonding prediction for skin-stiffener specimens was investigated. Geometrically nonlinear finite element analyses using two-dimensional plane-stress and plane-strain elements as well as three different generalized plane-strain type approaches were performed. The computed skin and flange strains, transverse tensile stresses and energy release rates were compared to results obtained from three-dimensional simulations. The study showed that for strains and energy release rate computations the generalized plane-strain assumptions yielded results closest to the full three-dimensional analysis. For computed transverse tensile stresses the plane-stress assumption gave the best agreement. Based on this study it is recommended that results from plane-stress and plane-strain models be used as upper and lower bounds. The results from generalized plane-strain models fall between the results obtained from plane-stress and plane-strain models. Two-dimensional models may also be used to qualitatively evaluate the stress distribution in a ply and the variation of energy release rates and mixed mode ratios with delamination length. For more accurate predictions, however, a three-dimensional analysis is required.

A new set of models, AE9/AP9/SPM, has been developed for use in space system design and other climatological applications. They describe energetic electron, proton, and plasma fluxes in the Earth’s inner magnetosphere based on 30 independent data sets from satellite-based sensors. The models provide particle flux maps including estimates of both measurement uncertainties and space weather variability. Furthermore, the model architecture permits the Monte-Carlo estimation of the time evolution of fluxes and derived quantities, e.g. the median and 95th percentile, along an arbitrary orbit. This overview will particularly address the latest AE9/AP9 version release.

Preconception care (PCC) and strict periconceptional glycemic control are both used to minimize the risk of congenital birth defects in offspring of women with type 1 or type 2 diabetes mellitus (DM). These malformations are ascribed in large measure to poor periconceptional control. This study evaluated PCC by a meta-analysis of published studies of PCC in women with DM, published from 1970 to 2000. Two reviewers independently abstracted the data, and the rate and relative risk (RR) of major and minor malformations were pooled from eligible studies using a random effects model. Early first-trimester values of glycosylated hemoglobin were recorded. Eight retrospective and eight prospective cohort studies were included; they were carried out in Europe, the United Kingdom, the United States, and Israel. Most participants had type 1 DM, but three studies included women with type 2 DM. Women given PCC tended to be about 2 years older on average than the others. Methods of PCC were quite variable, although most centers provided some maternal education about the pregnancy risks associated with poor glycemic control. In seven studies reporting early gestational glycosylated hemoglobin values, mean levels were consistently lower in PCC patients. Among 2104 offspring, the pooled rate for major and minor anomalies was 2.4% in the PCC group and 7.7% in non-PCC recipients, for a pooled RR of 0.32. Among 2651 offspring, major malformations were less prevalent in the PCC group (2.1 vs. 6.5%; pooled RR = 0.36). Comparable results were obtained when only prospective studies were analyzed and in studies where the infant examiners were unaware of the mothers' PCC status. The lowest risk of major anomalies was in a study that administered folic acid periconceptionally to its PCC recipients; the RR was 0.11. This meta-analysis, which included both retrospective and prospective studies, demonstrates an association of PCC with a significantly lower risk of congenital anomalies in the offspring of women with established DM. The lowered risk was accompanied by significantly lower glycosylated hemoglobin values in the first trimester in recipients of PCC.

Objectives: To study the pharmacokinetics of lithium chloride administered intravenously to patients who had undergone cardiac surgery within the previous 12 h and to normal volunteers, since lithium is used in a new indicator dilution method for measuring cardiac output. Methods: A prospective study was carried out in a London teaching hospital. Lithium chloride was administered intravenously and blood samples taken at intervals for up to one hour. Plasma lithium levels were measured by inductively coupled plasma optical emission spectrometry and standard pharmacokinetic parameters were calculated. Results: Two groups of patients were investigated; the first (n = 10) received five doses of 0.6 mmol LiCl at 2 min intervals, the second (n = 10) a single dose of 0.6 mmol LiCl. A further group of six normal volunteers also received a single dose of 0.6 mmol LiCl. Biexponential curves were fitted to the data. For the three groups the half-lives of the first exponentials (T1/2α) were 3.3, 4.2 and 3.9 min, resp...

Three models for the evolution of the ring current index Dst are evaluated for real-time implementation. Each model provides the time evolution of Dst in terms of solar wind parameters. Real-time data resources employed by the models are Kyoto Quicklook Dst and ACE real-time solar wind parameters. The implementation described provides a forecast time of about 1h due to propagation of the solar wind from the ACE spacecraft to the Earth. The models are evaluated for simulated real-time data availability, and several error measures are provided. One-hour averages were used in keeping with the standard Dst index. By all measures used the model of O'Brien and McPherron (1999, Journal of Geophysical Research, in press) performs best.

A consistent step-wise approach is presented to investigate the damage mechanism in composite bonded skin/stringer constructions under uniaxial and biaxial (in-plane/out-of-plane) loading conditions. The approach uses experiments to detect the failure mechanism, computational stress analysis to determine the location of first matrix cracking and computational fracture mechanics to investigate the potential for delamination growth. In a first step, tests were performed on specimens, which consisted of a tapered composite flange, representing a stringer or frame, bonded onto a composite skin. Tests were performed under monotonic loading conditions in tension, three-point bending, and combined tension/bending to evaluate the debonding mechanisms between the skin and the bonded stringer. For combined tension/bending testing, a unique servohydraulic load frame was used that was capable of applying both in-plane tension and out-of-plane bending loads simultaneously. Specimen edges were examined on the microscope to document the damage occurrence and to identify typical damage patterns. For all three load cases, observed failure initiated in the flange, near the flange tip, causing the flange to almost fully debond from skin. In a second step, a two dimensional plane-strain finite element model was developed to analyze the different test cases using a geometrically nonlinear solution. For all three loading conditions, computed principal stresses exceeded the transverse strength of the material in those areas of the flange where the matrix cracks had developed during the tests. In a third step, delaminations of various lengths were simulated in two locations where delaminations were observed during the tests. The analyses showed that at the loads corresponding to matrix ply crack initiation computed strain energy release rates exceeded the values obtained from a mixed mode failure criterion in one location. Hence, unstable delamination propagation is likely to occur as observed in the experiments.

Objective— To determine the effects of intraarticular administration of Samarium-153 (153Sm) bound to hydroxyapatite microspheres (153SmM) on an osteochondral chip–Ninduced synovitis. Study Design— Sixty days after implantation of autogenous osteochondral fragments in the middle carpal and metacarpophalangeal joints, 153SmM was administered into 1 joint of each type. The contralateral joints were used as untreated controls. Animals or Sample Population— Fifteen horses without preexisting joint disease were randomly divided into 2 groups (7 in the carpal group, 8 in the metacarpophalangeal group). Methods— Horses had osteochondral fragments that were harvested from the lateral ridge of the trochlea of the talus and implanted bilaterally into a middle carpal joint and a metacarpophalangeal joint; the opposite joint type served as a control. Sixty days later, 10 to 15 mCi of 153SmM (20 to 50 μm diam) was injected into the fragment-implanted joints. Three horses were treated with nonradioactive hydroxyapatite fragments. Horses were examined clinically until they were killed 14 or 30 days later. Control and treated joints were examined grossly and microscopically to determine the effects of 153SmM on synovial membrane and cartilage. Results— Intraarticular 153SmM caused a transient flare with lameness, effusion, and edema for 48 to 72 hours. Implanted osteochondral chips induced a synovitis characterized by variable degrees of joint damage and synovial infiltrate. Use of 153SmM resulted in synovectomy of variable depth and extent. Conclusions— Intraarticular 153SmM may be a useful method for synovectomy of inflamed synovial membrane. Clinical Relevance— With further testing, radioactive pharmaceuticals might become useful clinical treatments for persistent synovitis not responsive to conventional techniques.

An empirical model of the factors that determine the central axis dose at 10 cm depth in water for 4 MV, 6 MV and 18 MV photon beams is presented. Backscattering from the variable collimators into the dose monitoring ionization chamber can cause a variation of -0.5% to +1.8% in the dose per monitor unit in accelerators with an electron facility. Forward emission towards the isocentre from the beam flattening filter and upper collimators is more dependent on the position of the upper variable collimator blades than the lower blades, so that they are not interchangeable in determining output factors, which can differ by up to 2%. The model includes the product of the monitor backscatter factor, normalized phantom scatter factor, normalized head scatter factor and inverse square law, corrected for the displacement of the virtual x-ray focus from the target. It can predict the dose to -/+0.83% for 4 MV, -/+0.80% for 6 MV photons and -/+0.82% for 18 MV photons. The normalized head scatter factor is a second-order polynomial of the modified equivalent square collimator, whose coefficients do not vary significantly with x-ray energy. The model was tested by comparison with independent measurements of output factor and generally agreed to around 1%.

Sera from 516 participants enrolled in a population-based cross-sectional study in northwest Tanzania were tested for antibodies to hepatitis C virus (HCV). The mean age of study subjects was 29 years (range = 16-49 years); 43% were men, 6% reported a history of blood transfusion, and 4% were infected with human immunodeficiency virus-1 (HIV-1). Although 53 of 516 sera (10.3%, 95% confidence interval [CI] = 7.8-13.2%) were repeatedly reactive by a third-generation enzyme immunoassay (EIA-3), only 6 of the 53 were positive when tested with a third-generation recombinant immunoblot assay (confirmed HCV seroprevalence = 1.2%, 95% CI = 0.4-2.5%). The positive predictive value of the HCV EIA-3 in this population was 18.8% (95% CI = 7.0-36.4%). False positivity was not correlated with EIA-3 optical density values, age, sex, infection with HIV-1, or a history of blood transfusion, but it was marginally associated with increased serum IgG levels. We conclude that the prevalence of HCV is low in this region and that the HCV EIA-3 has a higher false-positivity rate in this population than has been reported among U.S. blood donors.

Objective.We have previously described an indicator dilutiontechnique of measuring cardiac output in which lithium chloride is injectedas a bolus via a central venous catheter and cardiac output derived from thearterial lithium dilution curve recorded from a lithium-selective electrode,which we have developed for this purpose. It would be an advantage if thelithium could be injected via the basilic vein (in the antecubital fossa) inthose patients who do not need central venous catheterisation for otherreasons. We have therefore compared cardiac output measurements made usingthese two routes of lithium chloride administration. Methods.Lithiumdilution cardiac output was measured 10 times in each of 10 patients,injecting the lithium chloride alternately via the basilic or central venouscatheter. Results.The mean difference was 0.8 ± 5.2% (SD)(range −8.5 to +7.0%) over a range of cardiac output of 4.5–13l/min. Conclusions.Injection of lithium chloride via the basilic veinin the antecubital fossa allows accurate lithium dilution cardiac outputmeasurements to be made in patients who do not have central venous cathetersin place.

Background Anesthetic induction and maintenance with propofol are associated with decreased blood pressure that is, in part, due to decreased peripheral resistance. Several possible mechanisms whereby propofol could reduce peripheral resistance include a direct action of propofol on vascular smooth muscle, an inhibition of sympathetic activity to the vasculature, or both. This study examined these two possibilities in humans by measuring the forearm vascular responses to infusions of propofol into the brachial artery (study 1) and by determining the forearm arterial and venous responses to systemic (intravenous) infusions of propofol after sympathetic denervation of the forearm by stellate blockade (study 2). Methods Bilateral forearm venous occlusion plethysmography was used to examine forearm vascular resistance (FVR) and forearm vein compliance (FVC). Study 1 used infusion of intralipid (time control) and propofol at rates between 83 and 664 micrograms/min into the brachial artery of 11 conscious persons and compared responses to arterial infusions of sodium nitroprusside (SNP) at 0.3, 3.0, and 10 micrograms/min. Venous blood from the infusion arm was assayed for plasma propofol concentrations. In study 2, after left stellate block (12 ml 0.25% bupivacaine + 1% lidocaine), six participants were anesthetized and maintained with propofol infusions of 125 and 200 micrograms.kg-1.min-1. Simultaneous right forearm (unblocked) blood flow dynamics served as the time control. In three additional conscious participants, intrabrachial artery infusions of SNP and nitroglycerin, both at 10 micrograms/min, were performed before and after stellate blockade of the left forearm to determine whether the sympathetically denervated forearm vessels could dilate beyond the level produced by denervation alone. Results In study 1, infusion of intralipid or propofol into the brachial artery did not change FVR or FVC. Sodium nitroprusside significantly decreased FVR in a dose-dependent manner by 22 +/- 5%, 65 +/- 3%, and 78 +/- 2% (mean +/- SEM) but did not change FVC. During the incremental propofol infusions, plasma propofol concentrations increased from 0.2 to 10.1 micrograms/ml and averaged 7.4 +/- 1.1 micrograms/ml during the highest infusion rate. In study 2, stellate ganglion blockade decreased FVR by 50 +/- 6% and increased FVC by 58 +/- 10%. Propofol anesthesia at 125 and 200 micrograms.kg-1.min-1 progressively reduced mean arterial pressure. In the arm with sympathetic denervation, FVR and FVC showed no further changes during propofol anesthesia, whereas in the control arm FVR significantly decreased by 41 +/- 9% and 42 +/- 7%, and FVC increased significantly by 89 +/- 27% and 85 +/- 32% during 125 and 200 micrograms.kg-1.min-1 infusions of propofol, respectively. In the three additional conscious participants, intraarterial infusion of SNP and nitroglycerin (TNG) after the stellate blockade resulted in a further decrease of FVR and a further increase of FVC. Conclusions In contrast to SNP infusions, propofol infusions into the brachial artery of conscious persons caused no significant vascular responses, despite the presence of therapeutic plasma concentrations of propofol within the forearm. The effects of propofol anesthesia on FVR and FVC are similar to the effects of sympathetic denervation by stellate ganglion blockade. Thus the peripheral vascular actions of propofol appear to be due primarily to an inhibition of sympathetic vasoconstrictor nerve activity.

With the FACSCount TM flow cytometer, counts of CD4, CD8 and CD3 lymphocytes and CD4/CD8 ratios were performed in a rural hospital in Tanzania. A total of 168 subjects (21 HIV-1 seropositive and 147 HIV-1 seronegative) were tested as part of a population-based serosurvey and AIDS education programme; 134 other subjects were hospitalized patients who had signs and symptoms suggestive of AIDS (69 HIV-1 seropositive and 65 HIV-seronegative). Mean values for the 147 HIV-1 seronegative subjects from the local population were 980 CD4 cells (95% CI 930, 1031), 598 CD8 cells (560, 635) and CD4/CD8 ratio 1.78 (1.68, 1.89). Seropositive subjects from the local population had significantly lower CD4 cell counts, higher CD8 counts and a lower CD4/CD8 ratio. CD4 cells were significantly lower and CD8 cells significantly higher in HIV-1 seropositive hospital patients compared to HIV-1 seronegative patients. However, 23 (35%) seronegative hospital patients had CD4 counts lower than 600. These results establish baseline values for the lymphocyte subsets in this population and indicate that this technique can be used in remote areas to monitor progress of HIV-infected individuals.

To evaluate the frequency, pattern, and severity of liver function test abnormalities in patients with Lyme disease associated with erythema migrans (EM), 115 individuals with no other identifiable cause for liver function test abnormalities who presented with EM between July 1990 and September 1993 were prospectively evaluated. For individuals with abnormal liver function tests, common causes of hepatitis, including hepatitis A, B, and C, were excluded. A local control group was used for comparison. Forty-six (40%) patients had at least one liver test abnormality, and 31 (27%) had more than 1 abnormality compared with 19 (19%) and 4 (4%) of controls, respectively (P < .01 for each comparison). gamma-Glutamyl transpeptidase (28%) and alanine transaminase (ALT) (27%) were the most frequently elevated liver function tests among Lyme disease patients. Anorexia, nausea, or vomiting was reported by 30% of patients, but did not occur more frequently in patients with elevated liver function tests compared with those with normal values. Patients with early disseminated Lyme disease were more likely to have elevated liver function studies (66%) compared with patients with localized disease (34%) (P = .002). After antibiotic treatment, elevated liver function tests improved or resolved in most patients. Liver function test abnormalities are common in patients with EM but were mild, most often not associated with symptoms, and improved or resolved by 3 weeks after the onset of antibiotic therapy in most patients.

We report the clinical outcome of arthroscopic labral reconstruction using a transglenoid suture technique in a young, active-duty military population. Forty-eight patients (49 shoulders) with varying degrees of gleno humeral instability underwent arthroscopic labral re construction using a transglenoid suture technique. All patients had traumatic injuries to their shoulders and all patients had magnetic resonance imaging scans dem onstrating anterior labral tears. Postoperatively, the patients' shoulders were immobilized for up to 6 weeks. At a mean followup of 30 months (range, 12 to 49), 17 of the 41 patients (41%) with preoperative dislocation or subluxation had recurrent instability. Nine of these patients subsequently underwent open reconstruction procedures for recurrent instability. On the basis of the Rowe rating system, 53% had excel lent or good results and 47% had fair or poor results. The overall perioperative complication rate was 14%. Suprascapular nerve palsy occurred in three cases (6%). Using the Fisher exact test, we determined that immobilization for 6 weeks postoperatively correlated with a lower recurrence rate in the patients with a history of glenohumeral dislocation (P = 0.007). The results of arthroscopic labral reconstruction using transglenoid sutures in the military patient are inferior to the reported 3% to 5% recurrence rate with open Bankart procedures, and the transglenoid pin tech nique jeopardizes the suprascapular nerve.

Intra-articular morphine has been shown to provide prolonged analgesia after arthroscopic knee surgery; the addition of local anaesthetic agents has been reported to improve this analgesic effect. Pethidine possesses local anaesthetic properties, and therefore this study was designed to evaluate its analgesic efficacy after arthroscopic meniscectomy. Sixty patients were allocated randomly to receive intra-articular injections of pethidine 50 mg, morphine 5 mg or saline after elective arthroscopic meniscectomy. Postoperative pain was assessed using an interval visual analogue scale and measuring analgesic requirements. Both treatment groups had significantly lower pain scores compared with the control group. Patients in the pethidine group had lower pain scores than those in the morphine group at 0.5, 1 and 2 h, but significantly higher scores at 12 and 24 h. These observations suggest that the local anaesthetic effect of pethidine may be responsible for the improved early analgesia, but its duration of action appears to be less than that of morphine.

Developmental morphology of the forelimb distal phalanges and lateral palmar processes of 9 Thoroughbred foals aged 3–32 weeks was assessed using radiography, microradiography and histology. For inclusion in the study, all distal phalanges had no pathologic radiographic abnormalities. Vascular channels that are characteristically found in the dorsal region of the distal phalanx were not evident radiographically in the palmar process. The proximal and distal angles of the palmar processes were separated by a lucent line continuous with the incisure in foals only through 12 weeks of age. The distal phalanges were triangular-shaped in foals 3–12 weeks of age, and were oval-shaped in older foals. The palmar aspect of the distal phalanx was the major contributor to growth of the distal phalanx in the sagittal plane, especially between 3 and 12 weeks of age. Growth of the lateral palmar process occurred through the means of endochondral ossification. The body and cortices of the lateral palmar process were composed of coarse cancellous bone. Porosity within the lateral palmar process was greater in regions sampled axial, compared to abaxial, to the parietal sulcus and did not change with age. A fracture was identified microradiographically and/or histologically in 9 of 18 (50%) and 10 of 17 (59%), respectively, of the lateral palmar processes examined. The fracture line was consistently associated with the parietal sulcus on the dorsal cortical surface and was always immediately abaxial to the deep digital flexor tendon attachment. No age-related morphological changes of the lateral palmar processes were identified with microradiography or histological examinations.

A simple beam element used at Bell Helicopter was incorporated in the Computational Mechanics Testbed (COMET) finite element code at the Langley Research Center (LaRC) to analyze the responce of tappered laminates typical of flexbeams in composite rotor hubs. This beam element incorporated the influence of membrane loads on the flexural response of the tapered laminate configurations modeled and tested in a combined axial tension and bending (ATB) hydraulic load frame designed and built at LaRC. The moments generated from the finite element model were used in a tapered laminated plate theory analysis to estimate axial stresses on the surface of the tapered laminates due to combined bending and tension loads. Surfaces strains were calculated and compared to surface strains measured using strain gages mounted along the laminate length. The strain distributions correlated reasonably well with the analysis. The analysis was then used to examine the surface strain distribution in a non-linear tapered laminate where a similarly good correlation was obtained. Results indicate that simple finite element beam models may be used to identify tapered laminate configurations best suited for simulating the response of a composite flexbeam in a full scale rotor hub.

The radiographic and pathologic findings of two Peruvian Paso foals with osteopetrosis are described. Both foals, one male and one female, presented with respiratory difficulty, brachygnathia and failure to rise after birth. Both foals were mildly anemic, hypogammaglobulinemic and had elevations in serum alkaline phosphatase. Increased medullary bone opacity was noted on radiographs of the extremities, spine and skull in both foals. A lack of normal cortical:medullary bone distinction was evident radiographically. The medullary primary spongiosa appeared to run in parallel columns away from the physes of all long bones and the vertebrae. This created a distinctive hour glass appearance to the osteopetrotic bones. One foal developed a bacterial pneumonia. Both foals were euthanized due to failure to thrive. Histopathology and electron microscopy documented these foals to have normal osteoclastic numbers but lack normal ruffled borders, lack of a clear zone and normal lysosomal numbers indicative of cellular dysfunction. These clinical, radiographic and pathologic findings are similar to the juvenile, lethal autosomal recessive form of osteopetrosis described in humans. Osteopetrosis has not been previously described in a female foal.

Summary Complete thoracic radiographic examinations were performed on 7 horses ranging in age from 24 to 60 months, followed by in-situ lung fixation. Radiographs were examined by 3 radiologists for the presence, degree and distribution of generalised pulmonary patterns within a region of interest in the caudodorsal lung. Pulmonary tissue was obtained from 12 sites within a designated volume of interest in the caudodorsal lung, corresponding to the area of interest evaluated radiographically, and examined for the presence, character and severity of microscopic lesions. Radiographic findings within the volume of interest consisted of mild to moderate bronchial, bronchointerstitial, or interstitial pulmonary patterns. Interstitial and bronchointerstitial radiographic findings were related to severity of peribronchiolar mononuclear cell infiltrates, the degree of bronchiolar mucosal plication, and alveolar capillary and peribronchial blood vessel erythrocyte content. The severity of the interstitial radiographic pattern was inversely associated with the perceived diagnostic quality of the radiographic examinations. There was no evidence of spatial variation in the severity of the microscopic changes examined in this limited pulmonary region. Inter-rater reliability between radiologists was good in the assessment of diagnostic quality of the radiographic examinations but poor in assessing severity of the primary generalised pulmonary patterns within the radiographic region of interest.

The distal phalanx and metacarpal physis of both forelimbs of 32 Thoroughbred foals 3-32 weeks of age were radiographed to identify those limbs with osseous bodies at a palmar process (PP) of the distal phalanx. Osseous bodies (ossicles) were identified radiographically in 19% of the foals. Sixteen of the 32 foals were selected for microradiographic and histological evaluation: 6 foals with radiographic evidence of ossicles and 10 foals without. Fourteen ossicles of the PP were observed radiographically. Ossicles were either a triangular bone fragment at the palmar aspect of the distal angle of the PP, or an oblong bone fragment separated from P3 by a radiolucent line extending 1-3 cm from the incisure of the PP to the solar margin. One foal had radiographic evidence of bilateral distal metacarpal physitis. Seventeen of 35 PPs examined microradiographically were considered normal, in that the dorsal and solar cortices were thin with trabecular bone orientated parallel to the cortical surfaces, and there was a depression in the dorsal cortical surface (i.e. parietal sulcus). Abnormal microradiographic findings in the other 18 PPs included a fracture line extending from the dorsal cortical surfaces and trabecular bridging of the fracture gap. The fracture line was often continuous with the parietal sulcus. Microradiographic evidence of a fracture was found in 75% of foals evaluated. Normal histological findings in 16 PPs included thin dorsal and solar cortices with trabeculae orientated parallel to the cortical surfaces, parallel-fibred dense connective tissue attachments of the deep digital flexor tendon to the solar cortical surfaces, and a neurovascular bundle associated with the parietal sulcus.(ABSTRACT TRUNCATED AT 250 WORDS)

Maternal cocaine abuse has been associated with neonatal neurological and neurobehavioral problems of unknown pathogenesis. We administered a single intravenous dose of cocaine (2 mg/kg) to 12 unanesthetized pregnant sheep; their fetuses had been catheterized in utero 2 days before the study. We measured fetal cerebral blood flow (CBF), cerebral metabolic rate of O2 (CMRO2), mean arterial blood pressure (MAP), and blood gases before and 2, 5, 15, and 30 min after maternal cocaine injection. Fetal CBF increased by 37 +/- 33% (mean +/- SD) at 5 min and returned to baseline by 15 min. Regional brain blood flow changes paralleled CBF changes with the greatest increases occurring in cerebellum (54 +/- 43%) and brain stem (54 +/- 52%). Cerebral vascular resistance was decreased for cerebellum (22%) and brain stem (19%) but was unchanged for cerebral hemispheres and caudate. Increased CBF at 5 min was associated with a 20 +/- 9% increase in fetal MAP and a 38 +/- 13% decrease in fetal arterial O2 content. Fetal CMRO2 was unchanged. There was a decrease in fetal intestinal blood flow at 2 min, an increase in myocardial, adrenal, and renal blood flow at 5 min, and no change in placental blood flow. Maternal cocaine injection causes fetal hypoxemia, hypertension, and increased CBF. Possible mechanisms for cerebral vasodilation (in some areas) include hypoxemia, impaired autoregulatory response to increased blood pressure, and/or direct or indirect vascular effects of cocaine or its metabolites.

Longitudinal epiphyseal bracket (LEB) is a rare ossification anomaly in which an epiphysis brackets the diaphysis of a phalanx, metacarpal, or metatarsal. This abnormal epiphysis tethers longitudinal growth, resulting in a shortened and oval-shaped bone. Four patients with five LEBs were treated by central physiolysis and followed for a mean of 6 years. The patients had significant hallux varus deformity. Three patients had duplicated great toes, and two had tibia hemimelia significant enough to require epiphysiodesis as they neared adolescence. Resection of the LEB allowed the proximal and distal epiphysis to resume untethered growth. Silastic or methyl methacrylate was placed over the resected physis to prevent bony rebridging. The associated hallux varus deformity was corrected by capsulorrhaphy and K-wire fixation. In all patients, the metatarsal resumed longitudinal growth and correction of the hallux varus was maintained.

Twenty-four-hour ambulatory blood pressure measurements (ABPM) are likely to eliminate the stress of visits and observer bias in office blood pressure (BP) recordings, allow consideration of the circadian variability in BP, and correlate well with target organ damage. To define the prevalence of "white coat" hypertension in a rural community to a nonacademic setting, and to assess age and sex related differences, we studied 131 patients who had more than two prior office diastolic BP measurements greater than 90 mm Hg and less than 115 mm Hg. Blood pressure was measured every 10 to 60 min for 24 h using the SpaceLabs 90207 device. Office BP readings were higher than ABPM in the group as a whole, in individual age groups, and in both sexes. The differences were more pronounced at night. Average differences between office and ambulatory BP ranged between 14.4 +/- 1.7/2.9 +/- 2.0 (ABPM at 10:00), and 33.8 +/- 2.3/22.8 +/- 1.5 mm Hg (systolic/diastolic +/- SE) (ABPM at 01:00). The nighttime drop in systolic BP was not apparent in subjects more than 65 years old. Women had a proportionately higher mean office BP than men (115.0 +/- 0.9 office v 110.2 +/- 1.3 mm Hg ABPM in women and 112.3 +/- 0.9 v 104.3 +/- 1.1 mm Hg in men) (P = .013), and the elderly did not display the relationship between ambulatory and office mean BP seen in younger subjects (r = 0.15, P = .30 v r = 0.36, P = .0004, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

[1] Indications of the space environment hazard at any point in space and time along geosynchronous orbit (GEO) can be obtained using the set of rules described in this paper. These rules are implemented using real-time Geostationary Operational Environmental Satellite particle sensor data and the magnetic index Kp. These rules should be useful for both real-time and posthoc analysis of GEO spacecraft anomalies. The hazards covered are surface charging, internal charging, single-event effects due to solar particle events, and total dose (solar arrays). The system provides a “hazard quotient,” the ratio of the instantaneous to mission-averaged likelihood of an anomaly due to each hazard, based on environmental measurements. With the exception of total dose, the hazard quotients are derived from lists of on-orbit anomalies or their proxies, and it is assumed that the probability of future anomalies will share the same functional dependence on the environment exhibited by the anomalies in the lists. Hazard quotients are potentially more valuable to satellite operators than are raw measurements, as hazard quotients directly convey the statistical relationship between the radiation environment and the likelihood of an anomaly.

A damage-threshold/fail-safe approach is proposed to ensure that composite structures are both sufficiently durable for economy of operation, as well as adequately fail-safe or damage tolerant for flight safety. Matrix cracks are assumed to exist throughout the off-axis plies. Delamination onset is predicted using a strain energy release rate characterization. Delamination growth is accounted for in one of three ways: either analytically, using delamination growth laws in conjunction with strain energy release rate analyses incorporating delamination resistance curves; experimentally, using measured stiffness loss; or conservatively, assuming delamination onset corresponds to catastrophic delamination growth. Fail-safety is assessed by accounting for the accumulation of delaminations through the thickness. A tension fatigue life prediction for composite laminates is presented as a case study to illustrate how this approach may be implemented. Suggestions are made for applying the damage-threshold/fail-safe approach to compression fatigue, tension/compression fatigue, and compression strength following low velocity impact.