Search

The Relativistic Proton Spectrometer (RPS) on the Van Allen Probes spacecraft was a particle spectrometer designed to measure the flux, angular distribution, and energy spectrum of protons from $\sim60~\text{MeV}$ ∼ 60 MeV to $\sim2000~\text{MeV}$ ∼ 2000 MeV . RPS provided new information about the inner Van Allen belt: a nearby region of space that had been relatively unexplored because of the difficulties of making charged particle measurements there and the associated hazards to satellite operations. We met the primary mission objective of providing accurate data for the AP9 radiation specification model at the high energies where there were little to no data prior to the Van Allen Probes mission. Along the way, we were able to demonstrate the long-term stability of parts of the Inner Belt by comparison with short-lived space science missions that operated decades prior to Van Allen Probes. The most significant surprises were the agreement between RPS and some of those historical measurements and the discovery of a trapped population of $>30~\text{MeV}$ > 30 MeV leptons at the outer edge of the inner belt. This end-of-mission paper summarizes the instrument performance, calibration, data products, and specific science and engineering results, and includes suggestions for future investigations of intense radiation fields like those found within the inner belt.

Purpose The force–velocity relationship of muscular contraction has been extensively studied. However, previous research has focussed either on isolated muscle or single-joint movements, whereas human movement consists of multi-joint movements (e.g. squatting). Therefore, the purpose of this study was to investigate the force–velocity relationship of isovelocity squatting. Methods Fifteen male participants (24 ± 2 years, 79.8 ± 9.1 kg, 177.5 ± 6 cm) performed isovelocity squats on a novel motorised isovelocity device (Kineo Training System) at three concentric (0.25, 0.5, and 0.75 m s−1) and three eccentric velocities (− 0.25, − 0.5, and − 0.75 m s−1). Peak vertical ground reaction forces, that occurred during the isovelocity phase, were collected using dual force plates (2000 Hz) (Kistler, Switzerland). Results The group mean squat force–velocity profile conformed to the typical in vivo profile, with peak vertical ground reaction forces during eccentric squatting being 9.5 ± 19% greater than isometric (P = 0.037), and occurring between − 0.5 and − 0.75 m s−1. However, large inter-participant variability was identified (0.84–1.62 × isometric force), with some participants being unable to produce eccentric forces greater than isometric. Sub-group analyses could not identify differences between individuals who could/could not produce eccentric forces above isometric, although those who could not tended to be taller. Conclusions These finding suggest that variability exists between participants in the ability to generate maximum eccentric forces during squatting, and the magnitude of eccentric increase above isometric cannot be predicted solely based on a concentric assessment. Therefore, an assessment of eccentric capabilities may be required prior to prescribing eccentric-specific resistance training.

Maternal smoking during pregnancy (MSDP) has been robustly associated with externalizing problems and their developmental precursors in offspring in studies using behavioral teratologic designs (Wakschlag et al., Am J Public Health 92(6):966-974, 2002; Espy et al., Dev Psychol 47(1):153-169, 2011). In contrast, the use of behavior genetic approaches has shown that the effects commonly attributed to MSDP can be explained by family-level variables (D'Onofrio et al., Dev Psychopathol 20(01):139-164, 2008). Reconciling these conflicting findings requires integration of these study designs. We utilize longitudinal data on a preschool proband and his/her sibling from the Midwest Infant Development Study-Preschool (MIDS-P) to test for teratologic and family level effects of MSDP. We find considerable variation in prenatal smoking patterns both within and across pregnancies within families, indicating that binary smoking measures are not sufficiently capturing exposure. Structural equation models indicate that both conduct disorder and oppositional defiant disorder symptoms showed unique effects of MSDP over and above family level effects. Blending high quality exposure measurement with a within-family design suggests that it is premature to foreclose the possibility of a teratologic effect of MSDP on externalizing problems. Implications and recommendations for future studies are discussed.

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.

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.

Changes in actin organization in the living egg apparatus of Torenia fournieri from anthesis to post-fertilization have been investigated using microinjection and confocal microscopy. Our results revealed that the actin cytoskeleton displays dramatic changes in the egg apparatus and appears to coordinate the events of synergid degeneration, pollen tube arrival and gametic fusion during fertilization. Synergid degeneration occurs after anthesis and is accompanied by actin fragmentation and degradation. The actin cytoskeleton becomes organized with numerous aggregates in the chalazal end of the degenerating synergid, and some of the actin infiltrates into the intercellular gap between synergids, egg and central cell, forming a distinct actin band. An actin cap is present near the filiform apparatus after anthesis and disappears after pollen tube arrival. In the egg cell, actin filaments initially organize into a network and after pollination become fragmented into numerous patches in the cortex. These structures, along with the actin in the degenerating synergid and intercellular spaces form two distinct actin coronas during fertilization. The actin coronas vanish after gametic fusion. This is the first report of changes in actin organization in the living egg apparatus. The reorganization of the actin cytoskeleton in the egg apparatus and the presence of the actin coronas during fertilization suggest these events may be a necessary prelude to reception of the pollen tube and fusion of the male and female gametes.

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.

Protein kinase C (PKC) is a major regulator of a broad range of cellular functions. Activation of PKC has been reported to stimulate Na+ transport across frog skin epithelium by increasing the apical Na+ permeability. This positive natriferic response has not been observed with other epithelial preparations, and could reflect the specific experimental conditions of different laboratories, or species or organ specificity of the response to PKC. In the present study, measurements were conducted with skins and urinary bladders from the same animals of two different species. The PKC activator TPA uniformly increased the transepithelial Na+ transport (measured as amiloride-sensitive short-circuit current, ISC, across skins from Rana temporaria and Bufo marinus, and inhibited ISC across bladders from the same animals. Inhibitors of PKC (staurosporine, H-7 and chelerythrine) partially blocked the TPA-induced stimulation of ISC across frog skin. The specificity of the PKC response by amphibian skin could have reflected an induction of moulting, similar to that observed with aldosterone. However, light micrographs of paired areas of frog skin revealed no evidence of the putative moulting. Separation of stratum corneum from the underlying stratum granulosum could be detected following application of aldosterone. We conclude that the effect of PKC on epithelial Na+ channels is organ, and not species specific. The stimulation of Na+ permeability in amphibian skin does not arise from sloughing of the stratum corneum. These observations are consistent with the hypothesis that the natriferic action arises from the calcium-independent isozyme of PKC previously detected in frog skin.

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.

Activators of protein kinase C (PKC) stimulate Na+ transport (JNa) across frog skin. We have examined the effect of Ca2+ on PKC stimulation of JNa. Both the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) and the diacyl-glycerol sn-1,2-dioctanoylglycerol (DiC8) were used as PKC activators. Blocking Ca2+ entry into the cytosol (either from external or internal stores) reduced the subsequent natriferic effect of the PKC activators. This negative interaction did not simply reflect saturation of activation of the apical Na+ channels, since the stimulations produced by blocking Ca2+ entry and adding cyclic AMP were simply additive. The Ca2+ dependence of the natriferic effect could have reflected either a direct action of cytosolic Ca2+ on PKC or an indirect action on the final receptor site (the Na+ channel). To distinguish between these possibilities, the TPA- and phospholipid-dependent kinase activity of broken-cell preparations was assayed. The kinase activity was not stimulated by physiological levels of Ca2+, and in fact was inhibited at millimolar concentrations of Ca2+. We conclude that the effects of Ca2+ on the natriferic response to PKC activators are indirect. Reducing cytosolic uptake of Ca2+ may have stimulated Na+ transport by a chemical modification of the apical channels observed in other tight epithelia. The usual stimulation of Na+ transport produced by PKC activators in frog skin may reflect the operation of a nonconventional form of PKC. This enzyme is Ca2+ independent and seems related to the nPKC or PKC epsilon observed in other systems.

A study of seven cases of “discitis” is presented. The clinical features of the condition are described and one is presented in detail. The criteriae for diagnosis are defined. The importance and means of early diagnoses are discussed.

The structure and distribution of cell organelles were observed in the gametophytes of Adiantum capillus-veneris L. undergoing the first cell division induced by white-light irradiation. Under continuous red light, the nucleus is spindle-shaped, encased in a sheath of chloroplasts, and located some distance back from the tip. The apical pole of the nucleus has an invagination which contains microtubules. Two types of chloroplasts, both of which have starch and prolamellar bodies, may be distinguished. One is cigar-shaped and may be "anchored" at the cell membrane. The other is smaller, and more pleiomorphic. Two populations of microtubules may be distinguished within the cortical cytoplasm, one set aligned parallel to the long axis of the cell, the other set aligned circumferentially around the cell at the region of the dome except for the extreme apex. Some of these microtubules do not run for long distances. If cell division is induced by irradiation of the gametophytes with white light the vacuolation and swelling of the tip region begin at least 2 h after the induction and continue till 8-10 h, by which time the nucleus has reached the neck of the protonema. Very elongated and rather abnormal forms of mitochondria were noted during this period. During cell division, mitochondria aggregated at the poles of the spindle and at the equatorial plane of the spindle margin. After cytokinesis the vacuole system becomes fragmented and is redistributed uniformly throughout the tip cell, the daughter nucleus rounds up and becomes surrounded by oil droplets.

Sieve elements with thick, lignified walls are identified in the longitudinal bundles of the wheat leaf and appear to be functional. They are also present in several festucoid grasses but appear to be absent from the panicoid grasses examined.

A case of giant cell tumour of the distal femur in a 25 year old female is presented. Initially the patient presented with a pathological fracture and underwent currettage and bone grafting of the lesion. Recurrence of the lesion occurred 3 years after initial treatment. Endoprosthetic replacement of the distal femur and knee joint was performed with total excision of the tumour. The advantages of this form of treatment are discussed. The treatment of giant cell tumours of bone remains controversial (Parrish, 1966; Ellis, 1949; Marcoveet al, 1973). Recurrence of tumour after initial currettage and grafting carries a greater risk of malignant changes (Dahlinet al, 1970). Amputation is often then considered the treatment of choice. Recently, however, there has been a move towards more conservative ablative surgery culminating in the development of endoprosthetic replacement of the involved bone and joint (Burrowset al, 1975). We present a case of recurrent giant cell tumour of the distal femur who underwent endoprosthetic replacement of the distal femur and knee joint.

For a unidirectional lamina, the in-plane mechanical properties of interest areE11,E22, ν12, ν12 andG12. Only three of the first four listed are independent. The fourth may be calculated from the reciprocal relationshipE11 ν21 =E22 ν12, which results from stiffness-tensor symmetry. Measurement of any four of the five properties listed will completely characterize the in-plane mechanical properties. A longitudinal uniaxial tension test was used to evaluate longitudinal modulus and Poisson's ratio. A modified rail-shear apparatus was designed to measure shear modulus in a rail-shear orientation, as well as a totally constrained transverse modulus in a uniaxial tension test with an orientation transverse to the longest dimension of the specimen. A flexure test was also used to estimate transverse moduli, since the achievement of the totally constrained transverse-modulus measurement was impaired by the variability of load distribution and constraint across the breadth (10-in. length) of the specimen. An apparatus was designed that applied a line loading to the specimen, simply supported on two opposite sides, with the two remaining sides free. The feasibility of this technique was documented by comparing measured values of the transverse modulus and out-of-plane displacement for a [0°]4 specimen to values obtained from the Levy solution for bending of an orthotropic plate.

The overall morphology of the developing wheat embryo in relation to its neighbouring tissues is described. The embryo is “isolated” early in development, but appears to be a powerful sink for nutrients. It is supplied initially by hydrolysis of the nucellar parenchyma and later by hydrolysis of neighbouring endosperm cells, which are completely digested. Later on, the nucellar epidermis forms specialised cells that may be transfer cells opposite the groove at the base of the embryo. The accumulation of starch and protein appears to begin first in the basal tissues of the scutellum and coleorhiza.

The mechanisms of penetration of Phytophthora cinnamomi Rands into seedling eucalypt roots were studied by light and electron microscopy. Culture grown seedlings of root-rot tolerant Eucalyptus st johnii and root-rot susceptible Eucalyptus obliqua were inoculated with both zoospores and mycelium. Zoospores encysted on roots of both species and the germ tubes penetrated without the formation of appressoria. Swellings, previously described as appressoria, were formed when the germ tube was slow to enter the host by intracellular penetration. Vegetative hyphae penetrated both inter- and intracellularly into the zones of root elongation and differentiation, often through root hairs. Evidence of hydrolysis of the host cell-wall at the point of penetration was observed in electron micrographs. Several hours after the germ tube penetrated the epidermis, a thick plug of amorphous material formed in the germ tube slightly below the level of the outer walls of the epidermal cells, sealing off the hypha within the root. Behaviour of zoospores and germ tubes and the mechanism of penetration were similar on both hosts. Micrographs do not suggest any kind of a hypersensitive reaction by the host cells during the early stages of infection.

Hydrolyzed walls (birefringent, Periodic acid/Schiff negative, remnants of primary walls that also lack polyuronides with free carboxyl groups) are demonstrated in the primary xylem of wheat and bean leaves. Walls with similar properties have been found in the primary xylem of a variety of tissues from different species, and are believed to be ubiquitous. It is shown that the pit membrane of intervessel pits between tracheary elements of willow is also a hydrolyzed wall. Combined with the observation byLiese (1965) it seems likely that the removal of non-cellulosic polysaccharides from primary walls unprotected by lignin is a general phenomenon that occurs late in the autolysis of all tracheary elements. Parenchyma cells that abut autolyzing tracheary elements appear to react to hydrolytic attack in a number of ways that are illustrated and discussed.

1. The polychromatic staining of plant cell walls by toluidine blue O is described and illustrated. 2. The effects of various common fixatives and the effects of the pH of the staining solution are evaluated. 3. Simple and rapid procedures are described for preparing stained temporary mounts of fresh material, or permanent mounts of embedded and sectioned material. 4. The relationship between the polychromatic staining observed and the lignification of the walls is discussed.

The gene for superoxide dismutase-1 (SOD-1) is clearly on chromosome 21, although there is disagreement on the precise band location of SOD-1 on the long (q) arm of number 21. We report a patient with normal superoxide dismutase-1 (SOD-1) activity and an interstitial deletion of chromosome 21 resulting in monosomy for band q21. His phenotype is characterized by moderate mental retardation, a long narrow face, high and arched palate, cardiac murmur, undescended testes, and long hyperflexible extremities. The normal SOD-1 activity supports localization of this enzyme to 21q22.1.

THE occurrence of severe frost at moderate elevations within the Tropics must be rare. It seems worth while therefore to place on record in the columns of NATURE some portion at least of an official report on the low temperature which (as was stated in NATURE last week) occurred at Hongkong between the 15th and 18th of January

IN his recent letter1, Prof. Dreyer remarks that discoveries in East Africa may perhaps throw light on, and be interpreted with due regard to, problems in South Africa. For similar reasons the investigations in South Africa arouse like hopes among archaeologists elsewhere.