Search

Accumulation of cold ions trapped within a space-charge-limited sheath collapses the sheath, causing a transition to the inverse sheath mode. A driving mechanism creating trapped ions is charge-exchange collisions which occur between fast ions and cold neutrals. Due to the complex nature of the temporally evolving sheath, it is difficult to predict how long the transition takes. Depending on the properties of the plasma, emitted electrons, and neutrals, the time scale can range from microseconds to hours. For experimental situations, it is important to understand whether the sheath will transition to an inverse mode within the observation time allotted. In this paper, we establish a theoretical basis for defining transition time of the sheath in terms of plasma properties. Calculations include an analytical approximation for the length of the virtual cathode, the amount of charged particles in each layer of the space-charge-limited sheath, and a time for its transition to the inverse sheath. The theoretical model is then compared to 1D kinetic simulations of a space-charge-limited sheath with charge-exchange collisions present. The results are applied to estimate transition time scales for applications in laboratory plasma experiments, the lunar sheath, and tokamaks.

This article presents experimental data, and their comprehensive analysis, for a polystyrene foam (with an initial density of 0.623 g/cm3) subjected to large strains and high pressures. The data were obtained from unconfined uniaxial stress tests in compression (at two different strain rates), confined compression tests with compressive strains to almost 50%, and a tension test. The confinement for the compression tests consists of a steel cylinder with external strain gages to monitor the hoop strains due to the radial stresses from the compressed foam. The procedure used to analyze the data allows for a continuous determination of axial, radial and hoop stresses, pressure, and von Mises equivalent stress. A parametric finite element analysis was used to provide for the determination of the stresses from small strains to large strains approaching 50%. There is excellent agreement between test results for similar conditions, as well as the results from data obtained from the confined experiments with two different wall thicknesses. The strength (von Mises equivalent stress) is highly dependent on the pressure, but not as dependent on the strain. The strain rate has a significant effect on strength for the uniaxial stress tests, but only limited data were obtained. Constants were obtained for an existing computational model, and there is good correlation between the experimental data and the model.

Two 15-year-old Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) test plantations at Artvin, in the eastern Black Sea Coast Region of Turkey, were inspected in July 2003. Trees in both plantations had yellow-to-brown foliage, and most trees retained only the current year's needles, resulting in sparse tree crowns. Numerous minute, black fruit bodies were present along the rows of stomata on the lower surfaces of needles from both plantations. Laboratory examination revealed that the fruiting bodies that emerged through the stomata were those of Phaeocryptopus gaeumannii [Rohde] Petrak, the causal agent of Swiss needle cast (SNC). Although low infection levels are relatively harmless, heavily infected trees lose all but the current year's foliage, with resulting average volume growth reductions of 23 to 52% (2,3). The pathogen occurs throughout the natural range of Douglas-fir in western North America, where it is native, as well as in eastern North America, Europe, Australia, and New Zealand, where both host and fungus have been introduced (1,2). The pathway of introduction of the pathogen to Turkey is unknown. Douglas-fir is the only known host of P. gaeumannii, and the pathogen is not known to be seedborne. Where P. gaeumannii has been introduced outside of western North America, infected nursery stock has been considered the most probable source (1). However, the affected Artvin plantations were established with seedlings produced in Turkey by using seed obtained from various sources. Earlier Douglas-fir plantations in Turkey date from 1953 and were established by using seed originating from France. The possibility that the pathogen could have arrived with untracked Douglas-fir seedlings from outside Turkey imported by arboreta or private nurseries cannot be excluded. Alternatively, scattered Douglas-fir plantations could have served as links between the Artvin infestation and known infested areas in central and eastern Europe, with spread occurring via windborne ascospores, similar to the spread of the pathogen to Denmark from the British Isles (ca. 1930) (1). Presence of severe SNC infections in Douglas-fir test sites at Artvin could hamper efforts to use this species in operational forestry in Turkey. To our knowledge, this is the first report of the occurrence of Swiss needle cast on Douglas-fir in western Asia. Voucher specimens have been deposited in the Oregon State University herbarium (OSC 106394-106403). References: (1) J. S. Boyce. Phytopathology 30:649, 1940. (2) E. M. Hansen et al. Plant Dis. 84:773, 2000. (3) D. Maguire et al. West. J. Appl. For. 17:86, 2002.

Recent one-dimensional simulations of planar sheaths with strong electron emission have shown that trapping of charge-exchange ions causes transitions from space-charge limited (SCL) to inverse sheaths. However, multidimensional emitting sheath phenomena with collisions remained unexplored, due in part to high computational cost. We developed a novel continuum kinetic code to study the sheath physics, current flow and potential distributions in two-dimensional unmagnetized configurations with emitting surfaces. For small negatively biased thermionic cathodes in a plasma, the cathode sheath can exist in an equilibrium SCL state. The SCL sheath carries an immense density of trapped ions, neutralized by thermoelectrons, within the potential well of the virtual cathode. For further increases of emitted flux, the trapped ion cloud expands in space. The trapped ion space charge causes an increase of thermionic current far beyond the saturation limit predicted by conventional collisionless SCL sheath models without ion trapping. For sufficiently strong emission, the trapped ion cloud consumes the entire 2D plasma domain, forming a mode with globally confined ions and an inverse sheath at the cathode. In situations where the emitted flux is fixed and the bias is swept (e.g. emissive probe), the trapped ions cause a large thermionic current to escape for all biases below the plasma potential. Strong suppression of the thermionic emission, required for the probe to float, only occurs when the probe is above the plasma potential.

In a previous paper, the utility of partial least squares as a tool for predicting performance using marker-based models was demonstrated. Including interactions between markers in prediction models improved prediction efficacy. The objectives of this paper were to determine whether: (i) molecular marker models based on 1 yr's phenotypic data could be used to predict performance in a second year; (ii) models based on per se data would be useful in predicting testcross performance; and (iii) adding epistasis to a model would improve prediction in either case. Data for protein, oil, and starch were obtained from 500 S 2 lines and their testcrosses from the crosses of Illinois High Oil (IHO) x Illinois Low Oil (ILO) and of Illinois High Protein (IHP) x Illinois Low Protein (ILP) corn (Zea mays L.) strains. Adding epistasis to a model significantly increased predictive power both between years and for testcross performance. The proportion of variability accounted for when predicting testcross performance from per se performance was lower than when predicting performance in different years. In all cases, observed vs. predicted correlations were high enough to suggest they would be useful in marker-assisted, or marker-based, breeding.

The relative importance of density, acoustic velocity, and microfibril angle (MFA) for the prediction of stiffness (MOE) and strength (MOR) has not been well established for Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco). MOE and MOR of small clear specimens of mature wood were better predicted by density and velocity than by either variable alone (183 trees >20 years old, six specimens per tree, 1087 specimens total). Specimens sampled around the stem circumference had similar density (intraclass correlation coefficient t = 0.74) but not MOE (t = 0.40) or acoustic velocity (t = 0.32), indicating benefits from sampling several circumferential positions. For MOE, the path coefficients (β) were moderate for density and velocity. For MOR, β was only high for density. End-matched samples of one specimen per tree were analyzed with SilviScan. Simple correlations with MOE were highest for density (r = 0.67) and then acoustic velocity2 (0.53), MFA (–0.50), earlywood MFA (–0.45), and latewood proportion (0.40). Most correlations were weaker for MOR. Density had a higher β than did MFA for either MOE or MOR. In more complex path models, latewood proportion and latewood density were the most important contributors to MOE and MOR, and MFA was relatively unimportant. The path analyses showed what simple correlation did not: that latewood proportion has strong predictive value for Douglas-fir mature wood quality.

To be useful, adding epistasis to a prediction model must increase predictive power. The objectives of this study were to determine i) using partial least squares (PLS) techniques, whether the ability to predict performance can be increased by including epistasis in a prediction model; ii) whether relaxing the probability of preselecting a marker or interaction to include in the PLS analysis from 0.001 to 0.01 to 0.05 would increase predictive power; and iii) whether the proportion of variability accounted for could be raised to a level useful in breeding. Data for protein, oil, starch, and grain yield were obtained from 500 S 2 lines from the crosses of Illinois High Oil × Illinois Low Oil and of Illinois High Protein × Illinois Low Protein corn (Zea mays L.) strains. Lines per se and testcrosses were evaluated for oil, protein, and starch, and only testcrosses for grain yield. Adding epistasis to a model signifi cantly increased predictive power, as did increasing the probability level for inclusion of signifi cant markers and epistatic effects in the PLS analysis from 0.001 to 0.01 to 0.05. With epistasis in the model and P = 0.05, correlations of predicted and observed means were high enough to suggest they could be useful in breeding.

B-lymphocyte colony-forming cells and various B-lymphocyte developmental states were examined for expression of surface immunoglobulin. B-lymphocyte colony-forming-cells appeared to possess a significantly greater amount of surface immunoglobulin than did newborn 'virgin' B lymphocytes. In terms of surface immunoglobulin content and physical property characteristics (established previously) B-lymphocyte colony-forming cells resembled a more mature B-lymphocyte subset. This subset, as characterized in previous studies, consists of mature virgin B cells that develop from the newborn virgin B cells via a process of nonspecific antigen-induced differentiation. An alternative possibility that B-lymphocyte colony-forming cells are memory B lymphocytes has not been eliminated by this study.

Herpes zoster (HZ) is an often painful neurocutaneous syndrome resulting from reactivation of varicella-zoster virus (VZV) that has remained latent in sensory ganglia after primary VZV infection (varicella) [1–3]. The frequency and severity of HZ and its most common debilitating complication, postherpetic neuralgia (PHN), increase with age [4–9]. This age-related increase in disease correlates closely with the decline in VZV-specific T cell mediated immunity (VZV-CMI) that accompanies aging [10–14]. It is very unlikely that antibodies to VZV play a role in this relationship, because they do not decline with aging [13, 14]. Furthermore, HZ frequently occurs in circumstances when VZV-CMI is depressed while levels of VZV antibody are maintained by intravenous γ-globulin, such as those following hematopoietic stem cell transplantation [15–17] On the basis of these observations, it was hypothesized that HZ might be prevented or attenuated (i.e., less pain and PHN) in elderly individuals if their waning VZV-CMI could be boosted with a VZV vaccine [18–20]. Pilot studies indicated that VZV-CMI could be boosted in subjects ⩾60 years old with live attenuated Oka strain VZV vaccines [13, 14, 21, 22]. Subsequent trials demonstrated the safety and immunogenicity of a high-potency Oka/Merck VZV vaccine in elderly subjects, including persons with diabetes and chronic lung disease, and established the optimal vaccine formulation and potency (M.J. Levin et al., unpublished data) A double-blind, placebo-controlled trial (Veterans Affairs Cooperative Study 403: “The Shingles Prevention Study”) that involved 38,546 subjects ⩾60 years of age demonstrated that a high potency live attenuated Oka/Merck VZV vaccine (hereafter, “zoster vaccine”) significantly reduced the burden of illness due to HZ, understood in terms of a severity-by-duration measure of HZ pain and discomfort (i.e., the vaccine decreased the incidence of HZ and decreased the average severity of HZ in vaccinees who developed HZ), and substantially reduced the incidence of PHN in vaccine recipients [9]. The trial included an immunology substudy in which a subset of subjects had immunologic assessments performed before and after vaccination. We describe here the magnitude and kinetics of VZV-specific immune responses to zoster vaccine measured during the immunology substudy and their possible association with the occurrence of HZ

Using computer simulation, we evaluated the impact of using first-generation information to increase selection efficiency in a second-generation breeding program. Selection efficiency was compared in terms of increase in rank correlation between estimated and true breeding values (i.e., ranking accuracy), reduction in coefficient of variation of correlation coefficients (i.e., ranking reliability), and increase in realized gain, with best linear unbiased prediction (BLUP). The test populations were generated with varying parameters: selection strategy (forward vs backward selection of parents); number of parents (24∼96); number of crosses per parent (1∼8); heritability (0.05∼0.35); ratio of dominance to additive variance (0∼3); ratio of additive-by-site to additive variance (0∼3); and ratio of dominance-by-site to additive variance (0∼3). The two selection strategies gave distinct results. When parents of the second-generation crosses had been selected via backward selection, adding first-generation information markedly increased selection efficiency. Conversely, when parents had been selected via forward selection, first-generation information provided little increase in efficiency. The amount of increase depended more on heritabilities in both generations and less on dominance and genotype–by–environment effects. Including first-generation information helped more when there were many parents and few crosses per parent in the second generation. Only in the case of extremely low first-generation heritabilities was there no benefit to adding first-generation information in terms of improved ranking reliability and accuracy.

The possibility of early testing coastal Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) for Swiss needle cast (SNC; caused by Phaeocryptopus gaeumannii (Rohde) Petrak) tolerance was investigated using 55 Douglas-fir families from western Oregon. Seedlings were inoculated with P. gaeumannii naturally in the field and were visually scored for a variety of SNC symptom traits (i.e., needle and foliage color, and retention) at the seedling stage (age 2) and in "mature" (ages 10 and 12) trees at two test sites for both the seedling and mature ages. Seedlings were also assessed in the laboratory for SNC symptom traits, for proportion of needle stomata occluded with pseudothecia (PSOP), and for amount of P. gaeumannii DNA in needles. Although families differed significantly at both ages for all SNC symptom traits and for PSOP, they did not differ for amount of fungal DNA. Thus, genetic variation in SNC symptoms appears to be primarily due to differences in tolerance to the disease rather than to resistance to infection per se. Estimated individual-tree heritabilities for SNC symptom traits were low to moderate (mean hi 2 = 0.19, range 0.06-0.37) at both ages, and within each age-class these traits were moderately to strongly genetically correlated (mean rA = 0.69, range 0.42-0.95). Type B genetic correlations between SNC symptom traits in seedlings and mature trees ranged from 0 to 0.83 and were weakest for traits measured in the laboratory. Genetic gain estimates indicated that family selection for SNC tolerance (i.e., greener needles or greater foliage retention) at the seedling stage can be very effective in increasing tolerance in older trees. Resume : La possibilite d'utiliser un test precoce pour evaluer la tolerance du douglas de Menzies typique (Pseudot- suga menziesii var. menziesii (Mirb.) Franco) au rouge de Gaeumann (Phaeocryptopus gaeumannii (Rohde) Petrak) a ete evaluee a l'aide de 55 familles de douglas. Des semis ont ete inocules naturellement avec P. gaeumannii au champ et ont ete visuellement evalues pour une variete de symptomes du rouge (couleur des aiguilles et retention du feuillage) chez des semis (2 ans) et des arbres plus vieux (10 et 12 ans). Les semis ont ete evalues en laboratoire pour les symp

Summary This study examined 108 15-year-old Douglas-fir (Pseudotsuga menziesii var. menziesii) trees to investigate whether trees exhibiting less severe Swiss needle cast (SNC) symptoms were more resistant (had less fungal colonization) or more tolerant (maintained healthy foliage under similar infection levels). Trees were sampled from six open pollinated families that were categorized into three disease severity groups (two families for each group; mild, moderate and severe disease symptoms). The amount of retained foliage and level of discoloration were visually assessed on trees in the field. Fungal colonization (as determined by proportion of stomata occluded with pseudothecia and by amount of Phaeocryptopus gaeumannii DNA in sampled needles) was measured on 1- and 2-year-old needles in the laboratory. Trees in the different disease severity groups were similar with respect to amount of fungus in their needles, yet the trees in the mild symptom group retained higher proportions of needles and maintained greener foliage. The relationship between amount of P. gaeumannii in needles and SNC symptom severity was statistically significant (p < 0.05) for amount of fungal DNA in 1-year-old needles and average needle retention (NR) over the last four growing seasons. Average NR decreased with increased amount of pathogen DNA in the mild disease symptom families. This relationship was reversed in the severe disease symptom group and there was no relationship in the moderate disease symptom group. Because the amount of P. gaeumannii DNA in foliage did not differ significantly among the groups, differences in symptom severity were attributed to tolerance, not resistance. Visual scoring of individual trees for average NR over the past four growing seasons could be used to effectively assess for SNC tolerance in Douglas-fir.

Motor control problems that result from damage to the central nervous system can make it difficult to learn functional activities. Although several therapeutic approaches attempt to address such problems there is little evidence of their efficacy. Targeted Training is a new approach, based on a biomechanical analysis of the problem, which usually relies on specifically designed equipment. This paper describes the underlying theory, the development of functional specifications, the translation of these specifications into an engineering design and the clinical results of applying the equipment. The promotion of head and trunk control provides an example of the process.

The land area required for a marker-aided selection (MAS) program to break-even (i.e., have equal costs and benefits) was estimated using computer simulation for coastal Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) in the Pacific Northwestern United States. We compared the selection efficiency obtained when using an index that included the phenotype and marker score with that obtained using only the phenotype. It was assumed that MAS was restricted to within-family selection, that the rotation age was 50 years, and that growth rate (h2= 0.25), tree form (h2= 0.25), and (or) wood density (h2= 0.45) were the objects of improvement. Several population quantitative trait loci (QTL) models, selection population sizes, and interest rates were considered. When large selection population sizes were employed (500 trees per family) MAS gave considerable increases in efficiency of within-family selection; however, results showed that the combination of small selection population sizes (100 trees per family) and many QTL of moderate effect could lead to losses in gain from MAS compared with phenotypic selection. For many reasonable selection scenarios and the simplified assumptions in our model, the land base required for breeding programs to break-even is smaller or near to the limit of those in place under operational breeding programs in the region. Considerably more research is needed to reasonably predict whether MAS would be cost-effective in practice. However, before some of the basic research needed to implement MAS can be done, organizations need to establish large blocks of full-sib families to allow for QTL identification.

An algorithm is presented for the finite element analysis of dynamic elastic–plastic fracture mechanics. The algorithm allows crack propagation in any direction, but does not require remeshing or the definition of new contact surfaces. This is achieved by tracking the path of the crack tip and failing the elements crossed by the path such that they can no longer sustain deviatoric or tensile volumetric stresses. The edges of these failed elements simulate crack faces that can sustain only compressive normal tractions. This element-failure technique is compared to the predominant node-splitting technique by example calculations. The T∗ fracture parameter, which includes inertial effects, is employed to indicate propagation. A study of the convergence of T∗ with mesh refinement is included. Additional examples are presented to demonstrate the versatility of the element-failure algorithm.

The impact of increasing the number of crosses per parent (k) on the efficiency of roguing seed orchards (backwards selection, i.e., reselection of parents) was examined by using Monte Carlo simulation. Efficiencies were examined in light of advanced-generation Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) tree improvement programs where information is available from previous generations, seed orchards have reduced genetic variation as a result of selection, and dominance variation is small compared with additive variation. Both the efficiency of reselection and its associated variance leveled off after two or three crosses per parent. The information from previous generations did not significantly increase reselection efficiency.

Column experiments were conducted using ideal natural sands and stainless-steel beads to examine the complete dissolution behavior of an organic immiscible liquid. Trichloroethene (TCE) was used as the representative organic liquid. The elution curves exhibited multi-step behavior, with multiple extended periods of relatively constant contaminant flux. These secondary steady-state stages occurred at concentrations several orders-of-magnitude below aqueous solubility for the well-sorted sands. In contrast, the secondary steady-state stages occurred within one log of aqueous solubility for the poorly-sorted sand. The nonideal behavior is hypothesized to result from constraints to hydraulic accessibility of the organic liquid to flowing water, which may be expected to be mediated by the pore-scale configuration of the flow field and the fluid phases.

The binge drinking of alcohol combined with the ingestion of a nonsteroidal anti-inflammatory drug (NSAID) is a recently described cause of reversible acute renal failure. The pathogenetic mechanisms leading to acute tubular necrosis in this setting include the initial compromise in renal perfusion due to alcohol-induced extracellular volume contraction and the superimposed renal hemodynamic alterations induced by the NSAID that interfere with the renal autoregulation. Although alcohol may also cause rhabdomyolysis leading to acute tubular necrosis, this is usually not apparent in these cases. Previously, only three such cases have been reported but the incidence is likely to be higher in view of the prevalence of alcohol and NSAID use. Herein is presented another patient in whom the features of flank pain and acute renal failure in association with binge drinking and NSAID ingestion constitute a characteristic syndrome.

The constitutive relationships for an anisotropic material are established for shock wave propagation and nonlinear, large deformation computer programs, commonly referred to as hydrocodes. Stresses are formulated in terms of strains; the procedure for separating material compressibility effects (equation of state) from strength effects is formulated which permits the consistent calculation of stresses in the elastic regime, and allows the mean pressure to be defined in accordance with their scalar interpretations. Futher, this procedure permits the computation of inelastic response by scaling of deviatoric stresses, so the equivalent stress resides on a yield or failure surface, without changing the pressure. The procedure for computing the equivalent plastic strain and non-radial return to the yield surface, which results from a calculated overstress, is developed. Also, the transformation matrices for large deformation (rotation), necessary for transformation between material and geometric coordinates, are presented.

Primary and metastatic ovarian cystadenocarcinomas, carcinomas of low malignant potential (borderline tumors), benign ovarian cystadenomas, and normal ovaries were compared for immunoperoxidase detection of the ligands epidermal growth factor (EGF), transforming growth factor-alpha (TGF-alpha), amphiregulin (AR), cripto, and the receptors, epidermal growth factor receptor (EGF-R), and c-erbB-2. This matrix analysis of these EGF family members indicated no specific pattern of ligand or receptor expression with a specific ovarian histologic category except in the case of AR and TGF-alpha. AR was detected almost exclusively in borderline tumors, suggesting that these tumors may not arise as a pathological continuum between benign cystadenomas and invasive cystadenocarcinomas. Second, the presence of TGF-alpha immunoreactivity in the absence of coexpression of cripto or EGF appeared to be associated only with adenocarcinomas of high grade and stage.

Retrovirus-mediated gene transfer was used to obtain expression of the macrophage colony-stimulating factor (MCSF) receptor, c-fms, on hematopoietic lineages that normally do not express this receptor. Cultures of murine fetal liver cells infected with the c-fms retrovirus developed erythroid colonies in cultures stimulated with M-CSF. However, these colonies were fewer and less hemoglobinized than colonies in parallel cultures stimulated by erythropoietin. Culture of isolated clones demonstrated a direct action of M-CSF on erythroid clones. Culture of c-fms retrovirus-infected adult murine bone marrow cells showed megakaryocyte and novel macrophage-megakaryocyte clones when stimulated by M-CSF. Culture of isolated clones again confirmed a direct action of M-CSF on megakaryocyte clones. In contrast, M-CSF stimulation of c-fms-infected granulocytes and granulocyte progenitor cells did not elicit proliferation, enhanced survival, or functional stimulation of granulocytes. These findings provide evidence for both conservation and lineage restriction of signal transduction in normal hematopoietic cells.

Dynamin 2 (Dyn2), a large GTPase, is involved in receptor tyrosine kinase (RTK)-promoted cell migration. However, the molecular mechanisms by which Dyn2 regulates RTK-induced cell migration have not been established. Recently, we reported that tyrosine-protein phosphatase non-receptor type 11 (SHP-2) and phosphatidylinositol 3-kinase (PI3K) mediate platelet-derived growth factor receptor-α (PDGFRα)-promoted glioma tumor growth and invasion. Here, we show that Dyn2 is an effector downstream of the PDGFRα-PI3K/SHP-2 signaling in glioma cells. Depletion of endogenous Dyn2 by short hairpin RNAs (shRNAs) inhibited PDGFRα-stimulated phosphorylation of Akt, Erk1/2, Rac1 and Cdc42 activities, glioma cell migration and survival in vitro and tumor growth and invasion in the brains of mice. Dyn2 binds to SHP-2 and PI3K and colocalizes with PDGFRα at the invasive fronts in PDGF-A-stimulated glioma cells. Inhibition of SHP-2 by siRNA knockdown abrogated Dyn2 association with activated PDGFRα and PDGFRα activation of Rac1 and Cdc42, and glioma cell migration, thereby establishing a link between SHP-2 interaction with Dyn2 and the PDGFRα signaling. Furthermore, a dominant-negative SHP-2 C459S mutant inhibited PDGF-A-stimulated glioma cell migration, phosphorylation of Dyn2 and concomitantly blocked PDGFRα-induced Src activation. Inhibition of Src by Src inhibitors attenuated PDGF-A-stimulated phosphorylation of Akt and Dyn2 and glioma cell migration. Additionally, mutations of binding sites to PI3K, SHP-2 or Src of PDGFRα impaired PDGFRα-stimulated phosphorylation of Akt and Dyn2, and Dyn2 association with activated PDGFRα. Taken together, this study identifies Dyn2 as an effector that mediates PDGFRα-SHP-2-induced glioma tumor growth and invasion, suggesting that targeting the PDGFRα-SHP-2-Dyn2 pathway may be beneficial to patients with malignant glioblastomas.

The expression and localization of cripto-1 (CR-1), amphiregulin (AR) and transforming growth factor alpha (TGFalpha) were assessed by immunocytochemistry in 37 primary human gastric tumors, 30 noninvolved gastric mucosa samples that were adjacent to carcinoma but exhibited intestinal metaplasia and 37 adjacent, noninvolved gastric mucosa samples. Seventeen (46%), nineteen (51%) and twenty-one (57%) carcinomas showed staining for CR-1, AR and TGFalpha, respectively; whereas sixteen (53%), eight (26%) and five (17%) intestinal metaplasias were reactive with the anti-CR-1, anti-AR and anti-TGFalpha antibodies, respectively. In contrast, none of the normal, noninvolved gastric mucosa samples reacted with the TGFalpha antibody and only 1 (3%) of these samples showed weak staining with the anti-CR-1 antibody. However, 8 (21%) of the normal gastric mucosa samples showed moderate levels of staining with the AR antibody. Within the carcinomas, there was a slight trend for association between TGFalpha and CR-1 expression (p

The epidermal growth factor (EGF) receptor (EGFR) is activated by EGF and other EGF-like growth factors, including amphiregulin (AR). We characterized the localization and mitogenic action of AR in T3M4 and COLO-357 human pancreatic cancer cell lines and determined whether the presence of AR in human pancreatic cancers correlates with patient survival. Both T3M4 and COLO-357 cells were found to be extremely sensitive to AR, one-half maximal stimulation occurring at a concentration of 70 and 50 pM, respectively. The magnitude of the stimulatory effect was greater with AR than with EGF. Both cell lines exhibited AR immunostaining, which was present in a variable manner in the cytoplasm, nucleus and nucleoli. Immunohistochemical analysis of 62 pancreatic cancer tissues revealed the presence of nuclear and/or cytoplasmic AR immunoreactivity in the cancer cells. Cytoplasmic, but not nuclear localization of AR in the pancreatic cancer cells was associated with a statistically significant decrease in the post-operative survival period. The presence of EGFR alone in the cancer cells did not correlate with decreased survival, whereas coexpression of cytoplasmic AR and EGFR was associated with shorter survival. Distant metastases did not always exhibit cytoplasmic AR immunoreactivity. These findings point to the existence of an EGFR: AR autocrine loop in human pancreatic cancer which may contribute to its biological aggressiveness.

This article presents an algorithm to automatically convert distorted hexahedral elements into meshless particles during dynamic deformation. With this approach the initial mesh is composed only of elements, and the particles are generated only as needed when the elements become highly distorted. This allows the mildly distorted regions of the problem to be accurately and efficiently represented with finite elements, and the highly distorted regions to be robustly represented with meshless particles. This algorithm is an extension of a previous algorithm that converts distorted tetrahedral elements into particles. The algorithm for hexahedral elements is more complex because the faces of these elements are not planar, as they are for tetrahedral elements. Examples of high‐velocity impact are included to demonstrate the capabilities of this algorithm.

Spurgia esulae Gagne (= Bayeria capitigena Bremi of Solinas & Pecora), a multivoltine gall midge recorded on Euphorbia esula in Italy, was selected as a candidate for the biological control of leafy spurge ( Euphorbia esula L. “complex”) in North America. Its potential host range was studied in 1982 at Rome, Italy, and in 1984 at Albany, Calif., using populations associated with Euphorbia esula from San Rossore near Pisa, Italy. Of 56 plant species or varieties in 22 families tested at the Rome laboratory, the midge oviposited and completed its life cycle only on plants in the genus Euphorbia (subgenus Esula ). In the tests conducted in Rome, complete development occurred on five populations of North American leafy spurge (from Montana, Nebraska, North Dakota, Oregon, and Saskatchewan) and on European E. peplus L., E. cyparissias L., E. myrsinites L., E. characias L., E. serrulata Thuillier, and on E. lathyris L. from Chico and Castro Valley, Calif. Of 12 native North American Euphorbia species tested at Albany in 1984, four species in the subgenus Esula ( E. incisa Engelmann, E. palmeri Engelmann, E. robusta (Engelmann) Small, and E. spathulata De Lamarck) supported the complete development of S. esulae . The restricted host range suggested use of this midge as a biological control agent against leafy spurge in North America. Releases of S. esulae were made in Montana in 1985 and in North Dakota in 1986; this species became established in both states.

Manufacturers of planting machines have altered the designs and combinations of components to improve the reliability of row crop planters. The literature indicates a primary source of planting error is the operator. Four different row crop planter units were affixed to mobile stands and employed a hydraulic motor to propel the seed metering and associated mechanisms. A planter test stand was also designed and fabricated to provide students an opportunity to observe each planter operating. The test stand featured a variable speed conveyor belt which simulated ground speed of the planter. Students observed seed count and seed spacing on the belt and compared the actual results to those displayed on a planter monitor console Troubleshooting diagnostic exercises completed the educational experience in row crop planters.

Constitutive models for brittle materials such as glass can be very complex as they are dependent on strains, strain rates, pressures, temperatures, damage and other parameters. There may also be significant (pressure‐dependent) strength after failure such that the constitutive response is much different for intact material and failed material. A large number of laboratory tests is required to develop a comprehensive constitutive model. Another approach is to develop simple models by using penetration‐velocity data obtained from ballistic experiments. Here various functional forms of simple models (with a limited number of constants) can be used to (computationally) match the penetration velocity over a range of impact velocities. This allows for the determination of the most important parameters and it provides an approximation of the stresses that occur during penetration. This article presents several simple computational models for borosilicate glass, including single‐state models and dual‐state models (that include an intact strength and a failed strength).

For physiological and other flows it is often assumed that the pressure pulse wave speed is given by the classic Moens-Korteweg expression and this may be used, for example, to assist in the determination of in vivo blood vessel wall incremental Young's modulus. A number of physical factors affecting the value of this wave speed have been reviewed in the literature, but the effect of slight ovalling of the tube cross-section is rarely mentioned. The analysis for a tube of elliptic cross-section shows that even a very small degree of ovalling can cause quite substantial reductions in Young mode wave propagation velocities compared with the classic Moens-Korteweg expression. Bending-induced changes in cross-section shape with internal pressure increase the apparent elasticity of the tube wall. Experimental confirmation is provided by waterhammer wave speed measurements in a copper tube that has been ovalled by coiling. Even though the Young mode is not dominant in this case, as it would be for a physiological case, the measured wave speed is quite clearly less than the Moens-Korteweg theory and it can be shown that the small degree of measured tube ovality explains this.

For the first time optically detected cyclotron resonance (ODCR) has been demonstrated using a CO2 pumped far-infrared (FIR) laser instead of microwaves. Both the electron and the light-hole cyclotron resonances have been observed in GaAs, as well as the 1 s to 2p+ impurity transitions. Valence band quantum effects, well known in Ge, are resolved directly for the first time in GaAs and the electron cyclotron resonances show strong spin doublet in the highest quality MBE samples. The technique has remarkable resolution and sensitivity at low temperatures and, by contrast with other techniques that have been reported, the authors also observe the n=1 to 2 (polaron shifted) and higher spin doublet split resonances at helium temperatures and with low FIR laser power. The conduction band results are analysed on the five-band model and the implications of this model on the valence band results are discussed. The authors have determined the valence band inverse mass parameters to be: gamma 1=7.5, gamma 2=2.6, gamma 3=3.1, kappa =1.0.

This article addresses some issues and solutions for ballistic impact computations. A discussion of the strengths and weaknesses of existing computational techniques is presented, and this is followed by a description of a new computational technique that is well suited for ballistic impact computations. This new approach uses both finite elements and meshless particles. The initial grid is composed entirely of finite elements. Then as the solution progresses, the highly strained finite elements are automatically converted into meshless particles. Generally, most of the grid remains as finite elements, and this allows for an accurate and efficient solution for the less distorted portion of the problem. Only the highly distorted regions of the problem are converted into meshless particles, and these meshless particles can accurately and robustly represent the high distortions that the finite elements are not able to represent. Several examples are provided to illustrate this approach. Included is the capability to compute the formation of Behind Armor Debris (BAD) and to track it through large distances.

We attempt to answer one of the outstanding issues in turbulence — does asymptotic inertial range scaling exist and if so, does it exist in a complete or incomplete similarity form? Although we cannot form a firm conclusion our results suggest we are tantalizingly close.

In response to the need for a sophisticated powered upper-limb orthosis for use by people with disabilities and/or limb weakness or injury, the MULOS (motorized upper-limb orthotic system) has been developed. This is a five-degree-of-freedom electrically powered device having three degrees of freedom at the shoulder, one at the elbow and one to provide pronation/supination. The shoulder mechanism consists of a serial linkage having an equivalent centre of rotation close to that of the anatomical shoulder; this is a self-contained module in which power transmission is provided by tensioned cables. The elbow and pronation/supination modules are also self-contained. The system has been designed to operate under three modes of control: 1. As an assistive robot attached directly to the arm to provide controlled movements for people with severe disability. In this case, it can be operated by a variety of control interfaces, including a specially designed five-degree-of-freedom joystick. 2. Continuous passive motion for the therapy of joints after injury. The trajectory of the joints is selected by ‘walk-through’ programming and can be replayed for a given number of cycles at a chosen speed. 3. As an exercise device to provide strengthening exercises for elderly people or those recovering from injury or surgery. This mode has not been fully implemented at this stage. In assistive mode, prototype testing has demonstrated that the system can provide the movements required for a range of simple tasks and, in continuous passive motion (CPM) mode, the programming system has been successfully implemented. Great attention has been paid to all aspects of safety. Future work is required to identify problems of operation, and to develop new control interfaces.

We previously reported the prevalence and associations of abdominal aortic aneurysm (AAA) in 73451 veterans aged 50 to 79 years who underwent ultrasound screening.To understand the prevalence of and principal positive and negative risk factors for AAA, and to assess reproducibility of our previous findings.In the new cohort of veterans undergoing screening, 52 745 subjects aged 50 to 79 without history of AAA underwent successful ultrasound screening for AAA, after completing a questionnaire on demographics and potential risk factors.We detected AAA of 4.0 cm or larger in 613 participants (1.2%; compared with 1.4% in the earlier cohort). The direction and magnitude of the important associations reported in the first cohort were confirmed. Respective odds ratios for the major associations with AAA for the second and for the combined cohorts were as follows: 1.81 and 1.71 for age (per 7 years), 0.12 and 0. 18 for female sex, 0.59 and 0.53 for black race, 1.94 and 1.94 for family history of AAA, 4.45 and 5.07 for smoking, 0.50 and 0.52 for diabetes, and 1.60 and 1.66 for atherosclerotic diseases. The excess prevalence associated with smoking accounted for 75% of all AAAs of 4.0 cm or larger in the total population of 126 196. Associations for AAA of 3.0 to 3.9 cm were similar but tended to be somewhat weaker.Our findings confirm our previous cohort findings. Age, smoking, family history of AAA, and atherosclerotic diseases remained the principal positive associations with AAA, and female sex, diabetes, and black race remained the principal negative associations.

Little is known about the rate at which new abdominal aortic aneurysms (AAAs) develop or whether screening older men for AAA, if undertaken, should be limited to once in a lifetime or repeated at intervals.A large population of veterans, aged 50 through 79 years, completed a questionnaire and underwent ultrasound screening for AAA. Of these, 5151 without AAA on the initial ultrasound (defined as infrarenal aortic diameter of 3.0 cm or larger) were selected randomly to be invited for a second ultrasound screening after an interval of 4 years. Local records and national databases were searched to identify deaths and AAA diagnoses made during the study interval in subjects who did not attend the rescreening.Of the 5151 subjects selected for a second screening, 598 (11.6%) had died (none due to AAA), and 20 (0.4%) had an interim diagnosis of AAA. A second screening was performed on 2622 (50.9%), of whom 58 (2.2%; 95% confidence interval, 1.6%-2.8%) had new AAA. Three new AAAs were 4.0 to 4.9 cm, 10 were 3.5 to 3.9 cm, and 45 were 3.0 to 3.4 cm. Independent predictors of new AAA at the second screening included current smoker (odds ratio, 3.09; 95% confidence, 1.74-5.50), coronary artery disease (odds ratio, 1.81; 95% confidence interval, 1.07-3.07), and, in a separate model using a composite variable, any atherosclerosis (odds ratio, 1.97; 95% confidence interval, 1.16-3.35). Adding the interim and rescreening diagnosis rates suggests a 4-year incidence rate of 2.6%. Rescreening only in subjects with infrarenal aortic diameter of 2.5 cm or greater on the initial ultrasound would have missed more than two thirds of the new AAAs.A second screening is of little practical value after 4 years, mainly because the AAAs detected are small. However, the incidence that we observed suggests that a second screening after longer intervals (ie, more than 8 years) may provide yields similar to those seen in initial screening and therefore warrants further study.

Few cross-national reports have examined suicide rates among adolescents and young adults. A survey of suicides among 15-24-year-olds in 34 of the wealthiest nations demonstrated that 15,555 youths killed themselves in a 1-year study period. Thirty-four percent of these suicides were firearm-related. Finland led the participating nations in total and firearm-related suicide rates. An association was found between divorce rates and youth suicide rates, firearm-related suicide among youths, and suicide rates among young males. For a smaller sample of countries, an association was found between firearm availability and firearm-related suicide rates among youths and suicide rates among young males.

We compared abdominal aortic aneurysm (AAA) prevalence in 3 groups of patients at the Hines Veterans Affairs Medical Center: (1) patients with 50% or more carotid stenosis, (2) patients with less than 50% stenosis, and (3) patients screened for the Aneurysm Detection and Management (ADAM) study.Of all the patients referred to the vascular laboratory for carotid duplex examination during a 12-month period, patients with 50% or more carotid stenosis underwent ultrasonography of the abdominal aorta unless they had a previous scan or previous aortic surgery (group 1, n = 374). Patients with less than 50% carotid stenosis who had been screened for ADAM comprised group 2 (n = 139). They were compared with all patients screened for ADAM at our center during the same time period (group 3, n = 2477).AAA of 3.0 cm or more were present in 18.2%, 12.2%, and 7.2% of groups 1, 2, and 3, respectively; AAA of 4.0 cm or more were present in 8.3%, 5.8%, and 2.1% of groups 1, 2, and 3, respectively. Among patients with carotid stenosis, those patients without diabetes accounted for the observed increase in prevalence (21.9 %or = 3.0 cm and 10.2%or = 4.0 cm vs 9.2% and 2.8% in patients with diabetes).The relative risk of AAA is 2 to 3 times greater in patients with carotid stenosis compared with patients undergoing routine screening. However, only patients without diabetes account for the increased prevalence. Selective AAA screening of patients who are not diabetic with carotid stenosis is recommended.

We have conducted a series of experiments to characterize the lesions that are precursors of cutaneous papillomas in SENCAR mice initiated with 7,12-dimethylbenz(a)anthracene (DMBA) and promoted with 12-O-tetradecanoylphorbol-13-acetate (TPA). The first grossly detectable lesions at sites where papillomas subsequently developed were papules, slightly raised areas of skin ranging in diameter from 0.25 to approximately 1.5 mm. Papules were first detected in DMBA-initiated mice 21 days after the start of dosing with TPA. Of 78 DMBA/TPA-induced papules tracked during 15 weeks of TPA treatments, 68% progressed to papillomas, 9% persisted as papules, and 22% completely regressed. Histological evaluation of serial sections of 69 DMBA/TPA-induced papules revealed that they were focal hyperplastic lesions that we refer to as squamous cell hyperplastic foci (SCHF). These hyperproliferative lesions appeared to progress through two distinct stages. Stage I SCHF were characterized as regular hyperplastic foci involving the interfollicular epidermis and the outer root sheaths of 1 or more hair follicles down to the level of the sebaceous glands. Stage II SCHF were foci of irregular epithelial hyperplasia with increased fibrovascular stroma and involved from 3 to10 hair follicles. Prominent dilated capillaries and inflammatory cell infiltrates were frequently associated with both stage I and II SCHF. Ha-ras gene codon 61 mutations were detected in 7 of 10 stage I SCHF and 13 of 14 stage II SCHF microdissected from histological sections and 7 of 7 of whole papules by mutation-specific PCR analysis. These data provide molecular evidence that SCHF are foci of initiated cells. Further study of these lesions may contribute to more fully defining the sequence of molecular and cellular changes necessary for tumorigenesis in mouse skin. SCHF may also have utility as early indicators of potential skin tumorigenicity in cancer bioassays.

The ErbB family of receptors, which include the epidermal growth factor receptor (EGFR), ErbB2, ErbB3, and ErbB4 mediate the actions of a family of bioactive polypeptides. EGF signals through EGFR, whereas heregulin (HRG) signaling is initiated through binding to either ErbB3 or ErbB4. In this report we studied the role of protein-tyrosine phosphatase SHP-2 in ErbB-mediated activation of mitogen-activated protein kinase (MAPK) by overexpressing SHP-2 mutants in COS-7 cells. We demonstrate that enzymatic activity and both NH2- and COOH-terminal SH2 domains of SHP-2 are required for EGF-induced MAPK activation, but not for c-Jun amino-terminal kinase stimulation or MAPK activation which occurred in response to myristoylated son of sevenless, activated Ras, or phorbol ester. Dominant-negative forms of SHP-2 had no effect on EGF-stimulated interaction of GRB2 with EGFR or SHC, nor did they influence phosphorylation of SHC and SHC/EGFR association. The same mutant SHP-2 structures that inhibited EGF-mediated stimulation of MAPK also blocked HRG alpha/beta-induced MAPK activation. EGF or HRG beta caused SHP-2 SH2 domains to engage multiple phosphotyrosine proteins, and mutation of either domain disrupted these associations. These results demonstrate that SHP-2 performs a common and essential function(s) in ligand-stimulated MAPK activation by the ErbB family of receptors.

The morphology and dimensions of the medullary canals of the proximal and middle phalanges have been studied with particular interest shown to the angle of taper of these canals. Measurements of 50 cadaveric fingers were taken from computer aided tomographic images using AutoCAD software. Tangents were fitted to the inner cortices in two orthogonal planes and the angles between them were measured. The angles of canal taper in the proximal phalanx were remarkably similar for each digit. This was also true for the middle phalanx of the index, middle and ring fingers but the taper of the middle phalanx of the little finger was found to be different.

To assess the effects of age, gender, race, and body size on infrarenal aortic diameter (IAD) and to determine expected values for IAD on the basis of these factors.Veterans aged 50 to 79 years at 15 Department of Veterans Affairs medical centers were invited to undergo ultrasound measurement of IAD and complete a pre-screening questionnaire. We report here on 69,905 subjects who had no previous history of abdominal aortic aneurysm (AAA) and no ultrasound evidence of AAA (defined as IADor = 3.0 cm).Although age, gender, black race, height, weight, body mass index, and body surface area were associated with IAD by multivariate linear regression (all p0.001), the effects were small. Female sex was associated with a 0.14 cm reduction in IAD and black race with a 0.01 cm increase in IAD. A 0.1 cm change in IAD was associated with large changes in the independent variables: 29 years in age, 19 cm or 40 cm in height, 35 kg in weight, 11 kg/m2 in body mass index, and 0.35 m2 in body surface area. Nearly all height-weight groups were within 0.1 cm of the gender means, and the unadjusted gender means differed by only 0.23 cm. The variation among medical centers had more influence on IAD than did the combination of age, gender, race, and body size.Age, gender, race, and body size have statistically significant but small effects on IAD. Use of these parameters to define AAA may not offer sufficient advantage over simpler definitions (such as an IADor = 3.0 cm) to be warranted.