bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of nutrients and zooplankton grazing on phytoplankton growth in a temperate reservoir in New South Wales, Australia
Authors: Kobayashi Tsuyoshi , Church Anthony G.
Published: September 2003

The role of nitrogen (N) and phosphorus (P) and zooplankton grazing on the growth of a phytoplankton community was investigated at different times in the Ben Chifley reservoir. In situ nutrient enrichment bioassays (n�= 12) indicated that phytoplankton growth was limited by P in 33% of experiments, by both N and P in 25% of experiments and no limitation was found in 42%. The hypothesis that N or P limitation occurred when ambient N : P ratios were different from the Redfield ratio was supported in 33% of bioassay experiments, suggesting that ambient N : P ratios do not always correctly indicate if N or P is limiting. Grazing rates of the reservoir zooplankton (>150�μm in size) ranged from 0.023–0.199 day–1 (mean: 0.078 day–1, n = 8). The grazing efficiency, as measured by a weight-specific clearance rate, ranged from 0.049–0.743 mL μg dry wt–1 day–1, and was positively correlated with the relative biomass of Daphnia in the community. The nutrient-stimulated growth of phytoplankton ranged from 0.085–1.031 day–1 (mean: 0.461 day–1, n = 10). The effect of nutrient enrichment exceeded that of zooplankton grazing in 62% of experiments. Further study is necessary to understand a qualitative effect of nutrients and zooplankton grazing on the phytoplankton community structure in the Ben Chifley reservoir.
Nothofagus kiandrensis (Nothofagaceae subgenus Brassospora), a new macrofossil leaf species from Miocene sediments at Kiandra, New South Wales
Authors: Paull Rosemary , Hill Robert S.
Published: September 2003

Nothofagus subgenus Brassospora is now confined to New Guinea and New Caledonia. Despite an impressive and highly diverse south-eastern Australian fossil pollen record for the subgenus (from Eocene, Oligocene and Miocene sediments), macrofossil finds have been rare and restricted to Tasmanian sites. Until now, only two subgenus Brassospora leaf species, N. serrata and N. mucronata (Early Oligocene, Little Rapid River, Tasmania) have been described. Nothofagus kiandrensis, from Early Miocene sediments at Kiandra NSW, is the first reported leaf species of subgenus Brassospora from mainland Australia.
Rubus anglocandicans (Rosaceae) is the most widespread taxon of European blackberry in Australia
Authors: Evans Katherine J. , Weber Heinrich E.
Published: September 2003

We identify the most widespread taxon of the Rubus fruticosus L. aggregate in Australia as a biotype of Rubus anglocandicans A. Newton, on the basis of morphological studies and analysis of M13/HaeIII DNA phenotypes using plant material collected from Australia, New Zealand, Europe and North America. Previous literature has confused this taxon with other Rubus taxa, especially R. procerus. We provide a full description and illustration of R. anglocandicans, including diagnostic characters separating it from R. armeniacus (R. procerus auct. mult.) and R. praecox. The morphology of R. anglocandicans in Australia differs slightly from specimens collected in England and it appears to exist as a clonal lineage, with 97% (n = 76) of samples characterised as DNA phenotype A. This taxonomic revision of this 'weed of national significance' will assist land managers in defining the weed problem prior to assessing management options that may vary in efficacy among species of the R.�fruticosus agg. Land managers have long assumed that Australia, New Zealand and north-western America share their most widespread biotype of the R. fruticosus agg.; namely, the taxon now known as R. armeniacus. R.�armeniacus, DNA phenotype B, was found in Germany, New Zealand and north-western America, but has not been identified in Australia to date.
Identification of functional horizons to predict physical properties for soils from alluvium in Canterbury, New Zealand
Authors: Webb T. H.
Published: September 2003

Lack of soil physical data, particularly soil water release data and hydraulic conductivity data, is recognised as one of the greatest limitations to the widespread application of simulation models, needed to address environmental issues. Because of the expense of generating new soil physical data pedotransfer functions may be used to predict soil physical data from existing information, notably soil morphology. Pedological horizon descriptions can then be used to estimate soil physical properties for many points in the landscape. The soils used in this study were derived from a systematic sampling of soil profiles for soil physical characteristics for 8 soils series within 2 drainage sequences on the post-glacial and glacial surfaces of the Canterbury Plains. Soil series in each sequence varied from shallow sandy loam, well-drained soils to deep clay loam, poorly drained soils. Each soil series was represented by 9 profiles. Three horizons in each soil profile were sampled for soil porosity values, particle size, and saturated- and near-saturated hydraulic conductivity. Pedological horizons were grouped into functional horizons on the basis of soil morphologic attributes expected to have closest relationships with soil physical properties (ped size, ped type, packing class, consistence and presence of argillic horizons). For topsoils, functional horizons based on ped size were found to have greatest predictive ability and provided separation between horizons for bulk density, macroporosity, clay content, wilting point, readily available water, and near-saturated hydraulic conductivity. For subsoils, horizons with clay content >35% had distinct relationships with soil physical properties and needed to be separated from other subsoil horizons. For the remaining horizons, separations in soil water release characteristics and some hydraulic conductivity data were obtained by functional horizons based on packing class and the presence of argillic horizons. Adding ped size to the functional horizon definition provided further separation of horizons for hydraulic conductivity. This study demonstrates that a range of pedological horizons, derived from a wide range of soil types, can be grouped into 4 functional topsoil horizons and 3–5 functional subsoil horizons on the basis of simple morphological attributes or merged pedological horizons. The functional horizons, thus created, enable statistical distributions of soil water release and hydraulic conductivity data to be predicted for map units.
Influence of soil treading on sediment and phosphorus losses in overland flow
Authors: McDowell R. W. , Drewry J. J. , Paton R. J. , Carey P. L. , Monaghan R. M. , Condron L.  M.
Published: September 2003

This study investigated the effect of simulated cattle treading on soil infiltration rate (saturated hydraulic conductivity: Ksat) and macroporosity, and the consequent loss of sediment and phosphorus (P) via overland flow from a grassland and cultivated soil used for dairy farming in southern New Zealand. Treading decreased soil macroporosity and Ksat, and hence time to ponding, which increased the volume of overland flow. Mean suspended sediment concentration was greater in the cultivated treatments (0.076 g/L) compared with the grassland treatments (0.014 g/L). In the grassland soil, sediment and particulate P fractions in overland flow increased with treading due to increased soil disturbance and decreased protection from erosion by grass cover. In contrast, for the cultivated soil, sediment and P concentration and load decreased with increasing treading, due to greater ponding which decreased the erosive power of raindrop impact. Dissolved and particulate P fractions followed similar trends, although mean total P (mostly particulate P) was greater in cultivated treatments (1.07 mg/L) than the grassland treatments (0.64�mg/L). Relationships were generated between macroporosity and the loss of sediment and P, showing the wider application of macroporosity for environmental assessment than solely an agronomic measurement.
Event erosivity factor and errors in erosion predictions by some empirical models
Authors: Kinnell P. I. A.
Published: September 2003

Analyses undertaken in this paper show that the Universal Soil Loss Equation (USLE) tends to overestimate low values of soil loss when the soil surface has a high capacity to infiltrate rainfall, but the degree of overestimation falls as the capacity of the soil to produce runoff increases. The USLE-M, a version of the USLE that uses the product of the runoff ratio and the EI30 as the event erosivity index, is more efficient in estimating soil loss because runoff is considered explicitly in the event erosivity index, whereas it is not in the USLE. The results show clearly that the problem of the USLE and the RUSLE overpredicting observed erosion losses, when erosion losses are low, is related to a large degree to model formula. In addition, the removal of restrictions to what constitutes a valid EI30 value increases the capacity of the RUSLE to overpredict low soil losses. As the USLE is an empirical model, values of USLE K, C, and P can only be used when the event erosivity parameter is EI30. Models like EPIC ignore this fact.
The use ofex situconserved plant genetic resources
Authors: Hodgkin Toby , Rao V. Ramanatha , Cibrian-Jaramillo Angélica , Gaiji Samy
Published: September 2003

Plant genetic resources are conserved so that they can be used to improve crop plant pro- duction and in other ways. However, it is often asserted that use ofex situconserved germplasm is inadequate and that genetic diversity maintained in genebanks is underutilized. In part, this reflects an incomplete recognition of what constitutes use of plant genetic resources, and of the many different ways in which material from genebanks contributes to improved agricultural production. Based on recent information from surveys of distribution of germplasm from genebanks, and from surveys of users, we suggest that the evidence indicates that there is substantial use ofex situconserved materials for a wide range of different uses. We suggest that barriers to use ofex situconserved germplasm may often result from a lack in numbers of users, and from limitations in capacity to effectively utilize the genetic diversity present in genebanks to reduce genetic vulnerability and increase sustainability in modern production systems.
Effects of fall dormancy of alfalfa on seed production at a northern latitude
Authors: Fairey D. T. , Fairey N. A. , Lefkovitch L. P. , Lieverse J. A. C.
Published: September 2003

The agri-climatic adaptation of an alfalfa variety in North America is categorized by its Fall Dormancy Rating (FDR1 = dormant to FDR9 = non-dormant). Presently, only relatively dormant, winter-hardy varieties (FDR1–4) are grown for seed and herbage at the northern latitudes of western Canada. However, there is considerably greater demand for seed of varieties that have FDR ≥ 4. A study was conducted in the Peace River region of north-western Canada to determine the relationship between FDR and seed production of alfalfa with FDR ≥ 4. Trials were established in each of two consecutive years with four varieties representing each of six FDR categories, FDR4–9. Growth characteristics were determined for two successive years of seed crops for each year of establishment. Seed yield (as a percentage of that for FDR4) was 84, 52, 40, 29 and 39% for FDR5 to FDR9, respectively, whereas total biomass at seed maturity was 89,73, 73, 57 and 57% for FDR5 to FDR9, respectively. Seed yield was more sensitive to changes in FDR than total biomass. Short rotations of specific alfalfa varieties with FDR ≥ 4 could be an option for seed growers in the northerly latitudes of western Canada, provided greater financial compensation is given for higher FDR varieties, and provided genetic drift can be retained within acceptable limits.
Simple and complex models for studying muscle function in walking
Authors: Pandy Marcus G.
Published: September 2003

While simple models can be helpful in identifying basic features of muscle function, more complex models are needed to discern the functional roles of specific muscles in movement. In this paper, two very different models of walking, one simple and one complex, are used to study how muscle forces, gravitational forces and centrifugal forces (i.e. forces arising from motion of the joints) combine to produce the pattern of force exerted on the ground. Both the simple model and the complex one predict that muscles contribute significantly to the ground force pattern generated in walking; indeed, both models show that muscle action is responsible for the appearance of the two peaks in the vertical force. The simple model, an inverted double pendulum, suggests further that the first and second peaks are due to net extensor muscle moments exerted about the knee and ankle, respectively. Analyses based on a much more complex, muscle–actuated simulation of walking are in general agreement with these results; however, the more detailed model also reveals that both the hip extensor and hip abductor muscles contribute significantly to vertical motion of the centre of mass, and therefore to the appearance of the first peak in the vertical ground force, in early single–leg stance. This discrepancy in the model predictions is most probably explained by the difference in model complexity. First, movements of the upper body in the sagittal plane are not represented properly in the double–pendulum model, which may explain the anomalous result obtained for the contribution of a hip–extensor torque to the vertical ground force. Second, the double–pendulum model incorporates only three of the six major elements of walking, whereas the complex model is fully 3D and incorporates all six gait determinants. In particular, pelvic list occurs primarily in the frontal plane, so there is the potential for this mechanism to contribute significantly to the vertical ground force, especially during early single–leg stance when the hip abductors are activated with considerable force.
Modelling primary and secondary growth processes in plants: a summary of the methodology and new data from an early lignophyte
Authors: Speck Thomas , Rowe Nick P.
Published: September 2003

A mathematical method, based on polar coordinates that allow modelling of primary and secondary growth processes in stems of extant and fossil plants, is summarized and its potential is discussed in comparison with numerical methods using digitizing tablets or electronic image analysing systems. As an example, the modelling of tissue distribution in the internode of an extant sphenopsid (
Equisetum hyemale
) is presented. In the second half of the paper we present new data of a functional analysis of stem structure and biomechanics of the early lignophyte
Tetraxylopteris schmidtii
(Middle Devonian) using the polar coordinate method for modelling the tissue distribution in stems of different ontogenetic age. Calculations of the mechanical properties of the stems, based on the modelling of the tissue arrangement, indicate that there is no increase in structural bending modulus throughout the entire development of the plant. The oldest ontogenetic stage has a significantly smaller bending elastic modulus than the intermediate ontogenetic stage, a ‘mechanical signal’, which is not consistent with a self–supporting growth form. These results, and the ontogenetic variations of the contributions of different stem tissues to the flexural stiffness of the entire stem, are discussed in the evolutionary context of cambial secondary growth.
Expression of Sea Anemone Equistatin in Potato. Effects of Plant Proteases on Heterologous Protein Production
Authors: Outchkourov Nikolay S. , Rogelj Boris , Strukelj Borut , Jongsma Maarten A.
Published: September 2003

Plants are increasingly used as production platforms of various heterologous proteins, but rapid protein turnover can seriously limit the steady-state expression level. Little is known about specific plant proteases involved in this process. In an attempt to obtain potato (Solanum tuberosum cv Desirée) plants resistant to Colorado potato beetle (Leptinotarsa decemlineata Say) larvae, the protease inhibitor equistatin was expressed under the control of strong, light-inducible and constitutive promoters and was targeted to the secretory pathway with and without endoplasmic reticulum retention signal. All constructs yielded similar stepwise protein degradation patterns, which considerably reduced the amount of active inhibitor in planta and resulted in insufficient levels for resistance against Colorado potato beetle larvae. Affinity purification of the degradation products and N-terminal sequencing allowed the identification of the amino acid P1-positions (asparagine [Asn]-13, lysine-56, Asn-82, and arginine-151) that were cleaved in planta. The proteases involved in the equistatin degradation were characterized with synthetic substrates and inhibitors. Kininogen domain 3 completely inhibited equistatin degradation in vitro. The results indicate that arginine/lysine-specific and legumain-type Asn-specific cysteine proteases seriously impede the functional accumulation of recombinant equistatin in planta. General strategies to improve the resistance to proteases of heterologous proteins in plants are proposed.
CYP83A1 and CYP83B1, Two Nonredundant Cytochrome P450 Enzymes Metabolizing Oximes in the Biosynthesis of Glucosinolates in Arabidopsis
Authors: Naur Peter , Petersen Bent Larsen , Mikkelsen Michael Dalgaard , Bak Søren , Rasmussen Hasse , Olsen Carl Erik , Halkier Barbara Ann
Published: September 2003

In the glucosinolate pathway, the postoxime enzymes have been proposed to have low specificity for the side chain and high specificity for the functional group. Here, we provide biochemical evidence for the functional role of the two cytochromes P450, CYP83A1 and CYP83B1, from Arabidopsis in oxime metabolism in the biosynthesis of glucosinolates. In a detailed analysis of the substrate specificities of the recombinant enzymes heterologously expressed in yeast (Saccharomyces cerevisiae), we show that aliphatic oximes derived from chain-elongated homologs of methionine are efficiently metabolized by CYP83A1, whereas CYP83B1 metabolizes these substrates with very low efficiency. Aromatic oximes derived from phenylalanine, tryptophan, and tyrosine are metabolized by both enzymes, although CYP83B1 has higher affinity for these substrates than CYP83A1, particularly in the case of indole-3-acetaldoxime, where there is a 50-fold difference in K  m value. The data show that CYP83A1 and CYP83B1 are nonredundant enzymes under physiologically normal conditions in the plant. The ability of CYP83A1 to metabolize aromatic oximes, albeit at small levels, explains the presence of indole glucosinolates at various levels in different developmental stages of the CYP83B1 knockout mutant, rnt1-1. Plants overexpressing CYP83B1 contain elevated levels of aliphatic glucosinolates derived from methionine homologs, whereas the level of indole glucosinolates is almost constant in the overexpressing lines. Together with the previous characterization of the members of the CYP79 family involved in oxime production, this work provides a framework for metabolic engineering of glucosinolates and for further dissection of the glucosinolate pathway.
Three Genes That Affect Sugar Sensing (Abscisic Acid Insensitive 4, Abscisic Acid Insensitive 5, andConstitutive Triple Response 1) Are Differentially Regulated by Glucose in Arabidopsis
Authors: Arroyo Analilia , Bossi Flavia , Finkelstein Ruth R. , León Patricia
Published: September 2003

Mutant characterization has demonstrated that ABI4 (Abscisic Acid [ABA] Insensitive 4), ABI5 (ABA Insensitive 5), and CTR1 (Constitutive Triple Response 1) genes play an important role in the sugar signaling response in plants. The present study shows that the transcripts of these three genes are modulated by glucose (Glc) independently of the developmental arrest caused by high Glc concentrations. ABI4 and ABI5 transcripts accumulate in response to sugars, whereas the CTR1 transcript is transiently reduced followed by a rapid recovery. The results of our kinetic studies on gene expression indicate that ABI4, ABI5, and CTR1 are regulated by multiple signals including Glc, osmotic stress, and ABA. However, the differential expression profiles caused by these treatments suggest that distinct signaling pathways are used for each signal. ABI4 and ABI5 response to the Glc analog 2-deoxy-Glc supports this conclusion. Glc regulation of ABI4 and CTR1 transcripts is dependent on the developmental stage. Finally, the Glc-mediated regulation of ABI4 and ABI5 is affected in mutants displaying Glc-insensitive phenotypes such as gins, abas, abi4, abi5, and ctr1 but not in abi1-1, abi2-1, and abi3-1, which do not show a Glc-insensitive phenotype. The capacity of transcription factors, like the ones analyzed in this work, to be regulated by a variety of signals might contribute to the ability of plants to respond in a flexible and integral way to continuous changes in the internal and external environment.
Communication between the Maternal Testa and the Embryo and/or Endosperm Affect Testa Attributes in Tomato
Authors: Downie A. Bruce , Zhang Deqing , Dirk Lynnette M.A. , Thacker Richard R. , Pfeiffer Janet A. , Drake Jennifer L. , Levy Avraham A. , Butterfield D. Allan , Buxton Jack W. , Snyder John C.
Published: September 2003

Two tomato (Lycopersicon esculentum) mutants with dark testae displaying poor germination rate and percentage on both water and 100 μm gibberellin4 + 7 were recovered. The mutants were allelic (black seed1-1; bks1-1 and bks1-2), inherited in Mendelian fashion as a recessive gene residing on chromosome 11. They are not allelic to bs (brown seed) -1, -2, or -4, which impair seed germination and possess dark testae. The bks/bs mutants accumulated dark pigment in the cell layers of the testa above the endothelium, which itself accumulated proanthocyanidins similar to wild type. The poor germination performance of bks mutant seeds was because of impediment of the mutant testae to radicle egress. Imbibition on gibberellin4 + 7 did not ameliorate germination percentage or rate. The toughening of the bks testa and associated poor germination were partially overcome when seeds were not dried before germination or were dried under N2. The seeds of the bks mutant have elevated activity of at least one enzyme responsible for the detoxification of reactive oxygen species. The bks mutant is epistatic to 12 anthocyaninless mutants of tomato. Bio- and physicochemical analysis of the bks testa determined that it accumulated a melanic substance. Inheritance of bks/bs mutations contrasts with that of the anthocyaninless mutants, which are inherited according to the genotype of the maternally derived testa. This suggests that the testa manufactures components before its demise that can maximize testa strength, whereas the endosperm/embryo produces factors that are conveyed to the testa, mitigating this process.
Insect Attack and Wounding Induce Traumatic Resin Duct Development and Gene Expression of (—)-Pinene Synthase in Sitka Spruce
Authors: McKay S. Ashley Byun , Hunter William L. , Godard Kimberley-Ann , Wang Shawn X. , Martin Diane M. , Bohlmann Jörg , Plant Aine L.
Published: September 2003

Conifers possess inducible terpenoid defense systems. These systems are associated with the formation of traumatic resin ducts (TRD) and are underpinned by enhanced gene expression and activity of terpene synthases (TPS), enzymes responsible for oleoresin formation. We first determined that Sitka spruce (Picea sitchensis [Bong.] Carriere) had the capacity for TRD formation by mechanically wounding representative trees. We then proceeded to investigate whether the white pine weevil (Pissodes strobi Peck.), a stem-boring insect, can influence the expression of genes encoding monoterpene synthases (mono-tps) in Sitka spruce. We went on to compare this response with the effects of a simulated insect attack by drill wounding. A significant increase in mono-tps transcript level was observed in the leaders of lateral branches of weevil-attacked and mechanically wounded trees. In this study, weevils induced a more rapid enhancement of mono-tps gene expression. A full-length Sitka spruce mono-tps cDNA (PsTPS2) was isolated, expressed in Escherichia coli, and functionally identified as (—)-pinene synthase. The recombinant (—)-pinene synthase catalyzes the formation of (—)-α-pinene and (—)-β-pinene, both of which are known constituents of stem oleoresin in Sitka spruce and increase in abundance after weevil attack. These data suggest that increased (—)-pinene synthase gene expression is an important element of the direct defense system deployed in Sitka spruce after insect attack.
Knock-Out of the Genes Coding for the Rieske Protein and the ATP-Synthase δ-Subunit of Arabidopsis. Effects on Photosynthesis, Thylakoid Protein Composition, and Nuclear Chloroplast Gene Expression
Authors: Maiwald Daniela , Dietzmann Angela , Jahns Peter , Pesaresi Paolo , Joliot Pierre , Joliot Anne , Levin Joshua Z. , Salamini Francesco , Leister Dario
Published: September 2003

In Arabidopsis, the nuclear genes PetC and AtpD code for the Rieske protein of the cytochrome b  6/f (cyt b  6/f) complex and the δ-subunit of the chloroplast ATP synthase (cpATPase), respectively. Knock-out alleles for each of these loci have been identified. Greenhouse-grown petc-2 and atpd-1 mutants are seedling lethal, whereas heterotrophically propagated plants display a high-chlorophyll (Chl)-fluorescence phenotype, indicating that the products of PetC and AtpD are essential for photosynthesis. Additional effects of the mutations in axenic culture include altered leaf coloration and increased photosensitivity. Lack of the Rieske protein affects the stability of cyt b  6/f and influences the level of other thylakoid proteins, particularly those of photosystem II. In petc-2, linear electron flow is blocked, leading to an altered redox state of both the primary quinone acceptor QA in photosystem II and the reaction center Chl P700 in photosystem I. Absence of cpATPase-δ destabilizes the entire cpATPase complex, whereas residual accumulation of cyt b  6/f and of the photosystems still allows linear electron flow. In atpd-1, the increase in non-photochemical quenching of Chl fluorescence and a higher de-epoxidation state of xanthophyll cycle pigments under low light is compatible with a slower dissipation of the transthylakoid proton gradient. Further and clear differences between the two mutations are evident when mRNA expression profiles of nucleus-encoded chloroplast proteins are considered, suggesting that the physiological states conditioned by the two mutations trigger different modes of plastid signaling and nuclear response.
Differential Metal Selectivity and Gene Expression of Two Zinc Transporters from Rice
Authors: Ramesh Sunita A. , Shin Ryoung , Eide David J. , Schachtman Daniel P.
Published: September 2003

Zinc is an essential mineral for a wide variety of physiological and biochemical processes. To understand zinc transport in cereals, we identified putative zinc transporters in gene databases. Three full-length cDNAs were identified and characterized from rice (Oryza sativa). Two of the cDNAs partially complemented a yeast (Saccharomyces cerevisiae) mutant deficient in zinc uptake at low concentrations. The two transporters showed many similarities in function but differed in ionic selectivity and pH optimum of activity. Expression patterns also differed between the two genes. One gene was broadly expressed under all conditions, and the other gene was mainly induced by zinc deficiency to higher levels in roots than in leaves. Although the timing of expression differed between the two genes, localization of expression overlapped in roots. Comparisons of the protein sequences, ionic selectivity, and gene expression patterns of the two transporters suggest that they may play different roles in the physiology of the whole plant.
The Gene Expression and Enzyme Activity of Plant 3-Deoxy-D-Manno-2-Octulosonic Acid-8-Phosphate Synthase Are Preferentially Associated with Cell Division in a Cell Cycle-Dependent Manner
Authors: Delmas Frédéric , Petit Johann , Joubès Jérôme , Séveno Martial , Paccalet Thomas , Hernould Michel , Lerouge Patrice , Mouras Armand , Chevalier Christian
Published: September 2003

3-Deoxy-d-manno-2-octulosonic acid-8-phosphate (Kdo-8-P) synthase catalyzes the condensation of phosphoenolpyruvate with d-arabinose-5-phosphate to yield Kdo-8-P. Kdo-8-P is the phosphorylated precursor of Kdo, a rare sugar only found in the rhamnogalacturonan II pectic fraction of the primary cell walls of higher plants and of cell wall polysaccharides of some green algae. A cDNA named LekdsA (accession no. AJ294902) encoding tomato (Lycopersicon esculentum) Kdo-8-P synthase has been isolated. The recombinant protein rescued a kdsA thermosensitive mutant of Salmonella typhimurium impaired in the synthesis of a functional Kdo-8-P synthase. Using site-directed mutagenesis of LekdsA cDNA, the tomato Kdo-8-P synthase was shown to possess the same essential amino acids that form the active sites in the bacterial enzymes. The tomato kdsA gene expression and the relevant Kdo-8-P synthase activity were preferentially associated to dividing cells, in the course of the early development of tomato fruit and in meristematic tissues. Furthermore, the transcription of the kdsA gene was found to oscillate during the cell cycle in tobacco (Nicotiana tabacum) Bright-Yellow 2 synchronized cells with a maximum during mitosis.
The Role of Chronic Peer Difficulties in the Development of Children's Psychological Adjustment Problems
Authors: Ladd Gary W. , Troop‐Gordon Wendy
Published: September 2003

A longitudinal investigation was conducted to explicate how the confluence of early behavioral dispositions, relational histories, and cognitive representations of the self and others contributes to internalizing problems, externalizing problems, and loneliness. One‐hundred and ninety three girls, and 206 boys were assessed annually from age 5 (kindergarten) to age 10 (Grade 4). Early aggressive behavior was related to Grade 4 maladjustment directly and indirectly through subsequent relational stressors. Significant associations emerged between chronic friendlessness and rejection and later adaptation not accounted for by concurrent relational difficulties. Self‐ and peer beliefs partially mediated the relation between peer difficulties and internalizing problems and loneliness. The results highlight the utility of child‐by‐environment models as a guide for the investigation of processes that antecede psychosocial maladjustment.
The Specificity of Environmental Influence: Socioeconomic Status Affects Early Vocabulary Development Via Maternal Speech
Authors: Hoff Erika
Published: September 2003

The hypothesis was tested that children whose families differ in socioeconomic status (SES) differ in their rates of productive vocabulary development because they have different language‐learning experiences. Naturalistic interaction between 33 high‐SES and 30 mid‐SES mothers and their 2‐year‐old children was recorded at 2 time points 10 weeks apart. Transcripts of these interactions provided the basis for estimating the growth in children's productive vocabularies between the first and second visits and properties of maternal speech at the first visit. The high‐SES children grew more than the mid‐SES children in the size of their productive vocabularies. Properties of maternal speech that differed as a function of SES fully accounted for this difference. Implications of these findings for mechanisms of environmental influence on child development are discussed.
Community Violence Exposure, Social Cognition, and Aggression Among Urban Elementary School Children
Authors: Guerra Nancy G. , Rowell Huesmann L. , Spindler Anja
Published: September 2003

The effects of witnessing community violence on aggressive cognitions and behavior were investigated in an ethnically diverse sample of 4,458 children living in urban neighborhoods. Prior violence exposure had a significant effect in increasing aggression, normative beliefs about aggression, and aggressive fantasy. Although exposure to violence predicted aggressive behavior both in Grades 1 through 3 (ages 5–8) and Grades 4 through 6 (ages 9–12), the effects on social cognition were only evident in the later grades. Furthermore, the effect of violence exposure on aggression in the later grades was partially mediated by its effect on social cognition. These findings suggest that witnessing community violence has an effect on children's aggressive behavior through both imitation of violence and the development of associated cognitions as children get older.
The Role of Hazardousness and Regulatory Practice in the Accidental Release of Chemicals at U.S. Industrial Facilities
Authors: Elliott Michael R. , Keindorfer Paul R. , Lowe Robert A.
Published: September 2003

This article presents the results of an analysis of the accident history data reported under section 112(r) of the Clean Air Act Amendments. These data provide a fairly complete record of the consequences of reportable accidental releases occurring during the time frame 1995–1999 in the U.S. chemical industry and covering 77 toxic and 63 flammable substances subject to the provisions of section 112(r). As such, these results are of fundamental interest to the affected communities, regulators, and insurers, as well as to owners and managers in the chemical industry. The results show the statistical associations between accident frequency and severity and a number of characteristics of reporting facilities, including their size, the hazardousness of the processes and chemicals inventoried, and the regulatory programs (in addition to section 112(r)) to which these facilities are subject. The results are interpreted in light of economic drivers of protective activity and regulatory priorities for monitoring and enforcement.
Analyzing the Cost of Screening Selectee and Non‐Selectee Baggage
Authors: Virta Julie L. , Jacobson Sheldon H. , Kobza John E.
Published: September 2003

Determining how to effectively operate security devices is as important to overall system performance as developing more sensitive security devices. In light of recent federal mandates for 100% screening of all checked baggage, this research studies the trade‐offs between screening only selectee checked baggage and screening both selectee and non‐selectee checked baggage for a single baggage screening security device deployed at an airport. This trade‐off is represented using a cost model that incorporates the cost of the baggage screening security device, the volume of checked baggage processed through the device, and the outcomes that occur when the device is used. The cost model captures the cost of deploying, maintaining, and operating a single baggage screening security device over a one‐year period. The study concludes that as excess baggage screening capacity is used to screen non‐selectee checked bags, the expected annual cost increases, the expected annual cost per checked bag screened decreases, and the expected annual cost per expected number of threats detected in the checked bags screened increases. These results indicate that the marginal increase in security per dollar spent is significantly lower when non‐selectee checked bags are screened than when only selectee checked bags are screened.
Source Material: The White House and the Press: News Organizations as a Presidential Resource and as a Source of Pressure
Authors: Kumar Martha Joynt
Published: September 2003

When a president comes into office today, he needs to have a communications operation in place ready to handle the queries of reporters and to take advantage of the enormous number of opportunities now present for a chief executive to speak to his various audiences, including those outside the United States. It is not a matter of choice for a president and his team. Looking at some facts and figures relating to the presence of reporters in the White House and recent patterns of public presidential remarks, one can understand the need a president has for an effective communications operation to manage his relations with the news organizations that carry his words to the public. This article explores the number of opportunities a president currently has to communicate with the public through his addresses and remarks and in his responses to queries from reporters. It does not assess how successful presidents have been in using the opportunities. It serves as a complement to the article in the June issue of the journal, Communications Operations in the White House of President George W. Bush: Making News on His Terms. That article describes a well‐functioning communications operation, and this piece focuses on why a president operating in today's environment needs to have such an organization to identify and to take advantage of existing opportunities to get to the public.
Titanium alloy material with very low outgassing
Authors: Kurisu H. , Muranaka T. , Wada N. , Yamamoto S. , Matsuura M. , Hesaka M.
Published: September 2003

In this communication we describe a titanium alloy material that has an excellent low outgassing property whose rate is lower than 6×10−13 Pa m s−1. This value is much lower than that of standard vacuum materials by three orders of magnitude under the same ordinary pretreatments. In our titanium alloy a natural TiO2 thin layer on the surface acts as an enhanced diffusion channel for dissolved gases, mainly hydrogen, consequently very quick evacuation of gas near the surface gives a very low outgassing rate.
Etch characteristics of (Pb,Sr)TiO3 thin films using CF4/Ar inductively coupled plasma
Authors: Kim Gwan-Ha , Kim Kyoung-Tae , Kim Dong-Pyo , Kim Chang-Il
Published: September 2003

The investigations of the (Pb,Sr)TiO3 (PST) etching characteristics in CF4/Ar plasma were carried out using the inductively coupled plasma system. Experiments showed that an increase of the Ar mixing ratio under constant pressure and input power conditions leads to increasing etch rate of PST, which reaches a maximum of 740 Å/min when the Ar is 80% of the gas mixture. To understand the etching mechanism, the surface state of the etched PST samples was investigated using x-ray photoelectron spectroscopy. It was found that Pb and Ti atoms were removed mainly by the ion-assisted etching mechanism. At the same time, Sr forms extremely low volatile fluorides and therefore can be removed only by physical (sputter) etching.
Influence of the incident angle of energetic carbon ions on the properties of tetrahedral amorphous carbon (ta-C) films
Authors: Liu Dongping , Benstetter Günther , Lodermeier Edgar , Vancea Johann
Published: September 2003

Tetrahedral amorphous carbon (ta-C) films have been grown on Ar+-beam-cleaned silicon substrates by changing the incident angle of energetic carbon ions produced in the plasma of pulsed cathodic vacuum arc discharge. Their surface roughness, deposition rate, composition, and mechanical and frictional properties as a function of the incident angle of energetic carbon ions were reported. The substrate holder can be rotated, and so an angle of deposition was defined as the angle of ion flux with respect to the substrate surface. While the deposition angle is varied from 20° to 59°, the root-mean-square (rms) roughness decreases from 0.5 to 0.1 nm, then it turns to increase at a slow rate when the deposition angle is over 77°. The variation correlates well with the one of hardness with the deposition angle and the films with lower rms roughness exhibit the higher hardness. The soft graphite-like surface layers existing at the surfaces of these films were revealed by atomic force microscopy-based nanowear tests and their thickness increases from 0.35 to 2.9 nm with the deposition angle decreasing from 90° to 30°. The soft surface layer thickness can have a great effect on the sp3 contents measured by x-ray photoelectron spectra. Nanoscale friction coefficient measurements were performed from lateral force microscopy by using a V-shaped Si3N4 cantilever. The low friction coefficients (0.076–0.093) of ta-C films can be attributed to their graphite-like surface structure. The implications of these results on the mechanisms proposed for the film formation were discussed.
Oxygenated polymeric thin films deposited from toluene and oxygen by remote plasma enhanced chemical vapor deposition
Authors: Barranco A. , Cotrino J. , Yubero F. , González-Elipe A. R.
Published: September 2003

Highly oxygenated polymeric films have been deposited by remote plasma enhanced chemical vapor deposition using a plasma of oxygen and toluene. The films grew in a very narrow range of pressures around ∼1 Torr, while at lower or higher pressures no deposition was observed. The differences in the optical emission spectra of the plasma corresponding to the deposition and nondeposition conditions reveal that the precursor is not effectively fragmented at low pressures. The films have been analyzed by ultraviolet–visible absorption spectroscopy, x-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy. The analysis by these techniques shows that the films have a high percentage of oxygenated functional groups (–OH, –CO, –COO) and a low percentage of hydrocarbon groups (C–H, –C–C–, –C=C–, etc.). The overall O/C ratio in these thin films was 0.8. Thin films with a lower O/C ratio have been obtained by applying a dc bias to the substrate and combining bias and Ar addition to the plasma. To study the possible use of the oxygenated polymeric thin films as sacrificial layers, the stability of the thin films has been studied under different etching treatments, including Ar and O2 plasma treatments and Ar+ ion bombardment. The high etching rates under oxygen plasma treatments at low pressures support the use of these thin films as sacrificial layers. It is also found that the etching rate of the different thin films increases with the content of oxygen.
Initial growth stage of nanoscaled TiN films: Formation of continuous amorphous layers and thickness-dependent crystal nucleation
Authors: Li T. Q. , Noda S. , Komiyama H. , Yamamoto T. , Ikuhara Y.
Published: September 2003

The initial growth stage of titanium nitride (TiN) deposited by reactive magnetron dc sputtering onto (111)-oriented Si substrates was investigated by using high-resolution transmission electron microscopy (HRTEM). During the initial growth stage, a continuous amorphous layer was observed when the deposited film was less than 1 nm thick. Crystal nucleation occurred from the amorphous layer when the film grew to about 2 nm thick. No preferred orientation was found for the initial crystal nuclei. The growth of the crystal grains depended on the N2 partial pressure, PN2. Increasing PN2 from 0.047 to 0.47 Pa enhanced lateral grain growth and coalescence between grains. For PN2=0.47 Pa, planar grains with a large lateral dimension were found formed by grain growth and coalescence, inducing a (200) film orientation. For films formed at PN2=0.47 Pa, an amorphous interlayer 1.5–1.8 nm thick formed between the TiN layer and Si substrate, and was indicated to be primarily SiNx by x-ray photoelectron spectroscopy and HRTEM. This interlayer was less than 0.5 nm thick in films formed at PN2=0.047 Pa.
Major advances in capture pumps in the last 50 years
Authors: Welch Kimo M.
Published: September 2003

Capture pumps either temporarily or permanently remove and store gases from a vacuum system by pumping mechanisms including chemisorption, physisorption, and particle implantation on pumping surfaces. All or only some of these pumping mechanisms might come into play depending on the type of capture pump. Momentum transfer pumps, having no inherent capacity limitation, whisk gases through their innards, compressing the gases for removal at a pump outlet. Because capture pumps retain pumped gases, they have inherent capacity limitations. Developments of capture pumps focused on improving both the capacity and throughput of these pumps. Some of the major advances in the development and use of capture pumps in the last fifty years are given. Specifically, comments are included on the developments of nonevaporable getters, sputter-ion pumps, titanium sublimation pumps, and cryopumps during this period.
Nanostructure science and technology: Impact and prospects for biology
Authors: Craighead H. G.
Published: September 2003

Life processes function by the activity of complex interacting molecular systems. Advances in nanostructure science and technology are providing powerful tools for investigating those systems. Developments such as atomic force microscopy, luminescent quantum dots, and nanofabricated probes have provided new capabilities for molecular and cell biology. The function of biomolecules, cellular components, and organelles and the interaction of living cells with their environment can now be explored in exquisite detail with nanoscale probes and devices. Materials and devices engineered at the nanometer scale are being developed and employed in biochemical analysis, medical diagnostics, and therapeutic devices. With the ability to understand, manipulate, and harness enzymes, receptors, and other biomolecules, new types of biosensors are emerging and new research approaches to biological systems are becoming possible.
Influence of modeling and simulation on the maturation of plasma technology: Feature evolution and reactor design
Authors: Graves David B. , Kushner Mark J.
Published: September 2003

Plasma materials processing for microelectronics fabrication, formerly an empirical technology, has in recent years greatly benefited from the use of modeling and simulation (MS) for equipment and process design. The maturation of plasma equipment and feature scale MS has resulted from a better understanding of the underlying physics and chemistry, from innovation in numerical algorithms and in the development of a more comprehensive fundamental database. A summary is presented of the historical development, present status and future potential of MS for feature evolution and plasma reactor design.
Photodesorption of gases in vacuum glazing
Authors: Ng N. , Collins R. E. , So L.
Published: September 2003

When samples of vacuum glazing are exposed to sunlight, the pressure within these devices is observed to increase. The major gas species released have been identified using mass spectroscopic techniques, and are found to be carbon monoxide and carbon dioxide rather than water vapor as in thermally degraded vacuum glazing. Different measuring techniques, including the use of a spinning rotor gauge, were developed to study the time dependence of pressure in samples of vacuum glazing during sunlight exposure. The mechanism associated with optical stability of vacuum glazing has been studied. High temperature baking during the evacuation stage of the manufacturing process for vacuum glazing greatly improves the stability of these devices under optical illumination.
Glycosylation Restores Survival of Chilled Blood Platelets
Authors: Hoffmeister Karin M. , Josefsson Emma C. , Isaac Natasha A. , Clausen Henrik , Hartwig John H. , Stossel Thomas P.
Published: September 2003

Cooling of blood platelets clusters the von Willebrand factor receptor complex. Macrophage α
M
β
2
integrins bind to the GPIbα subunit of the clustered complex, resulting in rapid clearance of transfused, cooled platelets. This precludes refrigeration of platelets for transfusion, but the current practice of room temperature storage has major drawbacks. We document that α
M
β
2
is a lectin that recognizes exposed β-
N
-acetylglucosamine residues of N-linked glycans on GPIbα. Enzymatic galactosylation of chilled platelets blocks α
M
β
2
recognition, prolonging the circulation of functional cooled platelets. Platelet-associated galactosyltransferase produces efficient galactosylation when uridine diphosphate–galactose is added, affording a potentially simple method for storing platelets in the cold.