bluuebunny/crossref_metadata_2025 huggingface dataset:
Going organic: using evolution in civils design
Authors: Ponterosso Pasquale , Fox Dominic
Published: February 2007

Products, buildings and infrastructure are starting to look more natural thanks to recent advances in engineering design, manufacturing and construction technology. Traditional hard, rectilinear structures are being replaced by softer, more organic forms—and not just because they look more natural: millions of years of evolution mean Earth's flora and fauna are engineered to near perfection. But while the enduring design of a mosquito might not give us the blueprint for a mosque, engineers can now replicate the natural process of evolutionary design for their own purposes. This paper introduces the genetic algorithm to civil engineering designers and presents summaries of recent research areas of application, including reinforced earth embankment design, truss optimisation, masonry arch collapse loads and mechanisms, and yield-line analysis of reinforced-concrete slabs. Whereas it cannot replace an engineering experience or judgement, the method appears to have great potential as an aid to more creative design.
Strength and hardening characteristics of activated fly ash mortars
Authors: Jo B.-W. , Park S.-K. , Park M.-S.
Published: February 2007

Utilisation of fly ash in raw materials would contribute to the elimination of an environmental problem and to the development of new high-performance materials. It is necessary to study the binders obtained by chemical activation of pozzolanic materials that could act as a substitute for existing cement. Fly ash contains a glass phase. Because it is produced under high temperatures, it is a chemically stable material. Fly ash consists mostly of SiO2 and Al2O3, and it assumes an oxide form on the inside of the fly ash. Because this reaction does not occur by itself, it is necessary to supply it with additional OH− from alkali activators. The current paper summarises the strength development of fly ash mortars under varying chemical activators, curing temperatures and curing ages. Also, reaction products of the alkali-activated fly ash were observed, using scanning electron microscopy and X-ray diffraction analysis. The main reaction product in mortar, activated with NaOH and water glass was zeolite of the type Na6(AlO2)6(SiO2)1012H2O. Feldspar [(Na, Ca)(Al, Si)2Si2O8] and hydrated calcium silicate (such as C–S–H or C–A–H gel) were also produced. Compressive strengths of 52·2 MPa and 57·3 MPa were observed at 3 days and 28 days, respectively, under high-temperature (90°C) curing.
Integrated Geophysical Survey for Site Investigation at a New Dwelling Area, Egypt
Authors: Elawadi Eslam , El-Qady Gad , Nigm Ahmed , Shaaban Fathy , Ushijima Keisuke
Published: February 2007

An integrated geophysical survey was carried out in a new dwelling area at 15-May town, southeast Cairo, Egypt. The buildings in this area are intensively affected by dangerous cracks that cause structural instability. The survey aimed to image the shallow subsurface structures, including karstic features, and evaluate their extent, as they may cause rock instability and lead to cracking of the residential buildings. Resistivity profiling (2-D), using a dipole-dipole array and ground penetrating radar (GPR) surveys were carried out along seven parallel traverses extending about [Formula: see text] between the buildings blocks. Additional measurements using a Schlumbereger array and very low frequency electromagnetic (VLF-EM) methods were conducted. The acquired data were processed and interpreted integrally to elucidate the shallow structural setting of the site. Integrated interpretation led to the delineation of hazard zones rich with karstic features in the area. Most of these karstic features are associated with vertical and sub-vertical linear features such as faults, fracture zones, and geologic contacts. These features are the main reason of the rock instability that resulted in potentially dangerous cracking of residential buildings.
Hydrogeological Effects on Superconducting Gravimeter Measurements at Metsähovi in Finland
Authors: Hokkanen Tero , Korhonen Kimmo , Virtanen Heikki
Published: February 2007

The purpose of this study is to gain a better knowledge of superconducting gravimeter (SG) data at the Metsähovi Gravity station in Southern Finland. Because SG data have a high precision [Formula: see text] and are very sensitive to various environmental effects, we must isolate and analyze the characteristics of these effects before we are able to consider their effects in data. As a result of extensive studies we have isolated four hydrogeological sources influencing the gravity field at the Metsähovi site. The first one, the time-varying amount of surface and soil water close to the station causes an immediate effect on gravity after rains. The second source, the water flow in the fractures of crystalline bedrock above the groundwater table below the station can be observed soon after rains. The third one, the porosity variation of the bedrock within the range of groundwater level variation is a long-term effect, which influence on the gravity field can vary over a wide range. The last source, the flow rate difference between soil and bedrock causes a detectable long-term gravity anomaly.
Issues During the Inversion of Crosshole Radar Data: Can We Have Confidence in the Outcome?
Authors: Clement William P.
Published: February 2007

One method of assessing the confidence in modeled features is to compare the results from different inversion schemes. I use synthetic traveltimes calculated from a model of an unconfined aquifer to determine the reliability of crosshole tomography. I compare the inverted models from straight and curved ray approximations to wave propagation. I investigate the effects of added random noise, regularization, the starting model, and the reference model on the curved ray inversion method. I also investigate the effects of different grid sizes for the forward model and of limited ray coverage through the earth model. Understanding the effects of these different methods and parameterizations will help place confidence limits on modeled features to more accurately reflect our knowledge of the subsurface. Straight or curved ray approximations to wave propagation resulted in similar models. However, the resolution estimates are substantially different and would lead to different assessments of the model reliability. Comparisons of the different choices for the model parameterization show that the resulting models are similar, indicating that tomography is a robust method. The most important factor to obtain reliable parameter estimates from crosshole radar tomography is to acquire wide aperture, densely sampled data with little noise.
Social Skills Interventions for Individuals with Learning Disabilities
Authors: Kavale Kenneth A. , Mostert Mark P.
Published: February 2007

Social skill deficits have become a defining characteristic of students with specific learning disability (SLD). Attempts have been made to enhance social functioning through structured training approaches. The effectiveness of these efforts was evaluated in a quantitative research synthesis (meta-analysis), which revealed a “small” effect with very few differences among teachers, peers, or students with SLD themselves who judged the efficacy of training. The relatively modest effects are discussed in relation to a number of theoretical psychometric and design issues that might account for the limited treatment outcomes.
Foundations and Research on Identifying Model Responsiveness-to-Intervention Sites
Authors: Mellard Daryl F. , Byrd Sara E. , Johnson Evelyn , Tollefson Julie M. , Boesche Liz
Published: February 2007

As regulations are rewritten regarding school-based learning disabilities identification practices, the components of those practices are likely to change. For example, cognitive assessment and aptitude-achievement discrepancy might be less important. A student's responsiveness-to-intervention (RTI) is emerging as an important construct for assessing underachievement. This article provides a framework for understanding how RTI fits as one LD determination component, describes research on RTI, and outlines the NRCLD's research efforts to examine current RTI implementation in schools and model site selection.
Habitat‐related error in estimating temperatures from leaf margins in a humid tropical forest
Authors: Burnham Robyn J. , Pitman Nigel C. A. , Johnson Kirk R. , Wilf Peter
Published: February 2007

Leaf margin characters are strong predictors of mean annual temperature (MAT) in modern plant communities and widely used tools for reconstructing paleoclimates from fossil floras. However, the frequency of nonentire‐margined species may vary dramatically between different habitats of the same forest. In this paper we explore the potential for this habitat variation to introduce error into temperature reconstructions, based on field data from a modern lowland forest in Amazonian Ecuador.

The data show that the provenance of leaves can influence temperature estimates to an important degree and in a consistent direction. Woody plants growing along lakes and rivers underestimated MAT by 2.5°–5°C, while those in closed‐canopy forest provided very accurate predictions. The high proportion of liana species with toothed leaves in lakeside and riverside samples appears to be responsible for a large part of the bias. Samples from closed‐canopy forest that included both lianas and trees, however, were more accurate than tree‐only or liana‐only samples.

We conclude that paleotemperature reconstructions based on leaf margin characters will be misleading to the extent that fossilization provides a better record of certain habitats than others. The preponderance of lake and river deposits in the angiosperm fossil record suggests that underestimation of mean annual paleotemperature may be common.
Fly‐pollinated Pleurothallis (Orchidaceae) species have high genetic variability: evidence from isozyme markers
Authors: Borba Eduardo L. , Felix Juliana M. , Solferini Vera N. , Semir João
Published: February 2007

We conducted an isozyme study in 22 populations of five Pleurothallis (Orchidaceae) species (12 loci in nine enzymatic systems). The genetic variability in all populations is surprisingly high (P = 58–83%, A = 2.1–3.8, He = 0.25–0.43) in spite of the fact that the five species are pollinated by small flies whose behavior enables self‐pollination. We suggest that self‐incompatibility, inbreeding depression, and mechanical barriers that prevent self‐pollination in these species are responsible for the maintainance of the high genetic variability. These traits are uncommon in Orchidaceae, but have been observed in these and some other species pollinated by flies or other pollinators with behavior that facilitates self‐pollination. The genetic similarity among conspecific populations is also high for species with very short‐range flying pollinators. Only one population of P. teres presented values of genetic similarity lower than usually observed in allopatric conspecific populations. Morphology, however, does not support its segregation as a new taxon. All species can be recognized by their enzymatic patterns, and the results agree with recently proposed taxonomic realignments. Conversely, the supposed affinities among these species based on floral morphology are not supported, and we hypothesize that it may be due to convergence in species with similar pollinators.
Drought stress, plant water status, and floral trait expression in fireweed, Epilobium angustifolium (Onagraceae)
Authors: Carroll Amy B. , Pallardy Stephen G. , Galen Candace
Published: February 2007

In a controlled environment, we artificially induced drought during flowering of Epilobium angustifolium, an animal‐pollinated plant. Leaf water potential (ψl) and floral traits were monitored over a 12‐d period of soil moisture depletion. Soil moisture depletion induced drought stress over time, as revealed by significant treatment × day interactions for predawn and midday ψl. Nectar volume and flower size showed significant negative responses to drought stress, but nectar sugar concentration did not vary between treatments. Floral traits were more buffered from drought than leaf water potentials. We used path analysis to examine direct and indirect effects of ψl on floral traits for plants in well‐watered (control) vs. drought treatments. According to the best‐fit path models, midday ψl has significant positive effects on flower size and nectar volume in both environments. However, for controls midday ψl also had a significant negative effect on nectar sugar concentration. Results indicate that traits influencing floral attractiveness to pollinators in E. angustifolium vary with plant water status, such that pollinator‐mediated selection could indirectly target physiological or biochemical controls on ψl. Moreover, under mesic conditions selection for greater nectar sugar reward may be constrained by the antagonistic effects of plant water status on nectar volume and sugar concentration.
Origin and evolution of the endemic genera of Gonosperminae (Asteraceae: Anthemideae) from the Canary Islands: evidence from nucleotide sequences of the internal transcribed spacers of the nuclear ribosomal DNA
Authors: Francisco‐Ortega Javier , Barber Janet C. , Santos‐Guerra Arnoldo , Febles‐Hernández Rosa , Jansen Robert K.
Published: February 2007

The Gonosperminae (Asteraceae) are composed of three genera endemic to the Canary Islands (Gonospermum Less., and Lugoa DC.) and southern Africa (Inulanthera Källersjö), and they are considered an example of a floristic link between these two regions. Phylogenetic analyses of ITS sequences reveal that the Canarian genera are not sister to Inulanthera and do not support the monophyly of the Gonosperminae. These results, coupled with previous phylogenetic studies of other groups, suggest that many of the putative biogeographic links between Macaronesia and southeast Africa need to be evaluated by rigorous phylogenetic analyses. Inulanthera forms part of the basal southern African radiation of the Anthemideae, and therefore it is closely related to other taxa from this region. Maximum likelihood and weighted parsimony analyses support a monophyletic group in the Canary Islands, that includes Lugoa, Gonospermum, and three Tanacetum species endemic to the island of Gran Canaria. Bootstrap support for the monophyly of this Canarian group is weak, and it collapses in the strict consensus tree based on unweighted parsimony. Lugoa is nested within Gonospermum, and both interisland colonization among the western islands of La Gomera, El Hierro, La Palma and Tenerife, and radiation on the central island of Gran Canaria have been the major patterns of species diversification for these Canarian endemics.
Why Firms Want to Organize Efficiently and what Keeps Them from Doing So: Inappropriate Governance, Performance, and Adaptation in a Deregulated Industry
Authors: Nickerson Jack A. , Silverman Brian S.
Published: February 2007

This paper integrates content-based predictions of transaction cost economics with process-based predictions of organizational change to understand adaptation to deregulation in the for-hire trucking industry. We predict and find that firms whose governance of a core transaction is poor (according to transaction cost reasoning) will realize lower profits than their better-aligned counterparts and that these firms will attempt to adapt so as to better align their transactions. Results show that several organizational features affect the rate of adaptation: (1) firms with large investments in specialized assets adapt less readily than firms that rely on generic assets, (2) firms with unions adapt less readily than firms without unions, (3) firms that must replace employee drivers with owner-operators adapt less readily than firms that must replace owner-operators with employee drivers, and (4) entrants adapt more quickly than incumbent carriers. There is evidence of institutional isomorphism in that although carriers move systematically to reduce misalignment, they do so less assiduously when this will make their governance of drivers look less like that of nearby, similar carriers. Finally, our results indicate that firms that ultimately exited adapted more quickly than firms that survived.
On the Weight of the Evidence from Cross Creek: A Reply to Turner
Authors: Fitzgerald Richard T. , Jones Terry L.
Published: February 2007

As stated in our original paper (Jones et al. 2002), the Cross Creek site is not of sufficient antiquity to challenge Clovis for temporal priority in western North America, but it pushes the age of the California Milling Stone culture back 2,000 years earlier than previous estimates. The Milling Stone culture and coastal adaptations on the southern California islands are so profoundly different from Clovis that they beg consideration of alternative colonization scenarios. Relying on old arguments and ignoring recently published findings, Turner (this issue) argues that there is insufficient evidence for a maritime culture on the central coast of California at the end of the Pleistocene. In our response, we further discuss implications of the findings from Cross Creek and other studies that support a coastal migration model.
A Neutral Model of Stone Raw Material Procurement
Authors: Brantingham P. Jeffrey
Published: February 2007

Stone tool assemblage variability is considered a reliable proxy measure of adaptive variability. Raw material richness, transport distances, and the character of transported technologies are thought to signal (1) variation in raw material selectivity based on material quality and abundance, (2) optimization of time and energy costs associated with procurement of stone from spatially dispersed sources, (3) planning depth that weaves raw material procurement forays into foraging activities, and (4) risk minimization that sees materials transported in quantities and forms that are energetically economical and least likely to fail. This paper dispenses with assumptions that raw material type and abundance play any role in the organization of mobility and raw material procurement strategies. Rather, a behaviorally neutral agent-based model is developed involving a forager engaged in a random walk within a uniform environment. Raw material procurement in the model is dependent only upon random encounters with stone sources and the amount of available space in the mobile toolkit. Simulated richness-sample size relationships, frequencies of raw material transfers as a function of distance from source, and both quantity-distance and reduction intensity-distance relationships are qualitatively similar to commonly observed archaeological patterns. In some archaeological cases it may be difficult to reject the neutral model. At best, failure to reject the neutral model may mean that intervening processes (e.g., depositional time-averaging) have erased high-frequency adaptive signals in the data. At worst, we may have to admit the possibility that Paleolithic behavioral adaptations were sometimes not responsive to differences between stone raw material types in the ways implied by current archaeological theory.
What Is Archaeology? (Or, Confusion, Sound, and Fury, Signifying…)
Authors: Bamforth Douglas B.
Published: February 2007

O'Brien, Lyman, and Leonard's comment misrepresents my paper and obscures the problems evolutionary archaeology faces. In particular, I took the ongoing operation of natural selection among modern humans as one of my fundamental assumptions and I did not limit evolution to genetic change. The assertion that the selectionists have identified the operation of natural selection in the archaeological record fails to meet the most basic standards of archaeological reasoning.
Implications of mating patterns for conservation of the endangered plantEriogonum ovalifoliumvar.vineum(Polygonaceae)
Authors: Neel Maile C. , Ross‐Ibarra Jeffrey , Ellstrand Norman C.
Published: February 2007

Mating patterns have direct application to conservation because of their influence on structuring genetic diversity within and among populations and on maintaining that diversity over time. We measured population and family outcrossing rates, biparental inbreeding, correlation of outcrossed paternity, and inbreeding coefficients in six populations from throughout the ecological range of the endangered plantEriogonum ovalifoliumvar.vineumusing naturally pollinated families. The taxon was primarily outcrossed: population outcrossing rates averaged 0.80 (SE 0.03) and family outcrossing rates averaged 0.88 (SE 0.03); neither rate varied among populations. Five population rates were significantly different from 1 while family rates differed from 1 in only one population. We found high correlated outcrossed paternity and evidence for biparental inbreeding in five populations each. As expected from the predominantly outcrossed mating system, levels of diversity were high and inbreeding coefficients among maternal individuals were low (averaging −0.05, SE 0.12). Differences between inbreeding coefficients of progeny (average 0.21, SE 0.06) and mothers indicated selection against homozygous offspring. These results indicate that it is important to maintain large populations to prevent increases in inbreeding and to maintain pollinator communities to facilitate outcrossing.
Variation in summer dormancy in the lilioid geophyte Burchardia umbellata (Colchicaceae)
Authors: Vaughton Glenda , Ramsey Mike
Published: February 2007

Plant dormancy is a form of phenotypic plasticity that minimizes exposure to seasonally stressful conditions. We examined variation in summer dormancy in two highland and two lowland populations of the lilioid geophyte Burchardia umbellata to test the prediction that facultative dormancy is advantageous in habitats with variable summer conditions. Consistent with this prediction fewer highland plants than lowland plants became dormant under wet common garden conditions. Also, significant among‐family variance occurred within highland but not lowland populations, indicating genetic differences among and within populations. Most lowland plants became dormant when exposed to wet or dry conditions (∼92%), indicating that dormancy was primarily obligate. In contrast, dormancy in highland plants increased from 44% under wet conditions to 93% under dry conditions, indicating that dormancy of some highland plants was facultative and induced by drought. Survival, growth, and flowering were reduced in lowland populations, and in dormant vs. nondormant highland plants, indicating costs of dormancy that could negate the advantages of dormancy under variable summer conditions. Summers in lowland populations are predictably hot and dry, favoring a phenotype that responds invariably to environmental cues that are correlated to future dry conditions. In highland populations, variable summer conditions probably maintain polymorphism in dormancy.
Biogeography and origin of Lilium longiflorum and L. formosanum (Liliaceae) endemic to the Ryukyu Archipelago and Taiwan as determined by allozyme diversity
Authors: Hiramatsu Michikazu , Ii Kaori , Okubo Hiroshi , Huang Kuang Liang , Huang Chi Wei
Published: February 2007

Allozyme diversity on 13 isozyme loci was investigated for two bulbous species, Lilium longiflorum and L. formosanum, endemic to the subtropical archipelago of continental origin located in East Asia. Degrees of allozyme variability and divergence for L. longiflorum were very high for insular endemic species, indicating relatively longtime persistence of the present widespread distribution across many islands in this phenotypically little‐changed species. Lilium formosanum exhibited rather lower variability and divergence than did L. longiflorum and was genetically close to the southern peripheral populations of L. longiflorum with 0.978 as its highest genetic identity value. Combined with other biological and insular geohistorical information, our results suggest that L. longiflorum was established around the end of the Pliocene when the current distribution area was still a continuous part of the ancient Asian continent, and L. formosanum was derived from southern populations of L. longiflorum around the late Pleistocene when the mainland of Taiwan was completely separated from the adjacent islands and the main continent. Depauperization of allozyme variability in some L. longiflorum populations was found on islands with lower altitudes. This reflects bottleneck effects after the complete or almost complete submergence of such low islands during the archipelago's development.
Molecular and morphological reassessment of relationships within the Vittadinia group of Astereae (Asteraceae)
Authors: Lowrey Timothy K. , Quinn Christopher J. , Taylor Rachael K. , Chan Raymund , Kimball Rebecca T. , De Nardi Jan C.
Published: February 2007

Morphological and ITS (internal transcribed spacer) sequence data for 40 species of the Austral‐Pacific genera Camptacra, Kippistia, Minuria, Peripleura, Tetramolopium, and Vittadinia as well as one semiherbaceous species of Olearia were subjected to cladistic analysis, separately and together. Minuria, Peripleura, and Tetramolopium are paraphyletic as currently defined. Tetramolopium vagans from Australia appears to represent an undescribed genus. Both Kippistia suadefolia and Peripleura diffusa show close affinity to Minuria species, and Minuria macrorhiza appears to contain two distinct but closely related species. Vittadinia and the remaining species of Tetramolopium and Peripleura form a strong affinity group. The distribution of indels and the combined analysis each provide evidence that the Hawaiian and Cook Island species of Tetramolopium are descended from New Guinea species. The combined analysis also suggests that the Cook Island species T. mitiaroense is sister to the Hawaiian clade. Olearia arguta groups strongly with Camptacra and shows no close affinity with either of the arborescent species of Olearia used to root these analyses. Marked homoplasy among morphological characters indicates why generic delimitation in the group has been problematic.
Effects of mycorrhizal infection and soil phosphorus availability on in vitro and in vivo pollen performance in Lycopersicon esculentum (Solanaceae)
Authors: Poulton Jennifer L. , Koide Roger T. , Stephenson Andrew G.
Published: February 2007

The effects of mycorrhizal infection and soil P availability on in vitro and in vivo pollen performance were studied in two cultivars of tomato (Lycopersicon esculentum). In the first study, plants were grown in a greenhouse under three treatment combinations: nonmycorrhizal, low P (NMPO); nonmycorrhizal, high P (NMP3); and mycorrhizal, low P (MPO). Mycorrhizal infection and high soil P conditions significantly increased in vitro pollen tube growth rates but not percentage of germination. In addition, pollen from NMP3 and MPO plants sired significantly more seeds than pollen from NMPO plants in pollen mixture studies. In the second study, plants were grown initially in a greenhouse under two treatment combinations: NMPO and MPO. After all plants began to flower, they were placed in experimental arrays in the field. Under open pollination, pollen from MPO plants sired significantly more seeds than pollen from NMPO plants. This result was primarily attributed to increased flower production (and thus pollen production) in MPO plants. Thus, mycorrhizal infection and high soil P conditions can increase pollen quality (in vitro and in vivo pollen performance) as well as pollen quantity, thereby enhancing fitness through the male function. Anthocyanin production (used to determine paternity) also affected pollen performance.
Seedling functional types in a lowland rain forest in Mexico
Authors: Ibarra‐Manríquez Guillermo , Martínez Ramos Miguel , Oyama Ken
Published: February 2007

Seedling morphology of 210 species (173 trees and 37 lianas) was studied from a community perspective to identify major patterns of seedling functional types in a Mexican rain forest. Five types of seedlings were distinguished: cryptocotylar with reserve storage or absorption cotyledons (epigeal [CER] and hypogeal [CHR]), phanerocotylar epigeal, either with photosynthetic cotyledons (PEF) or with reserve storage or absorption cotyledons (PER), and phanerocotylar hypogeal with reserve cotyledons (PHR). The most common seedling type was PEF (49.5%), followed by CHR (31.4%), PER (9.5%), PHR (7.2%), and CER (2.4%). Excepting the CER type, seedling type frequencies did not differ between trees and lianas. The PEF seedlings had the lightest seeds, whereas CHR seedlings had the heaviest ones. Pioneer trees showed lighter seeds than persistent trees or lianas in species with PEF but not in species with PER. Pioneer trees (38 species) showed three seedling types and the most common was PEF (82%). Persistent trees (135 species) showed the five seedling types but PEF (43%) and CHR (37%) were the most frequent. Seedling type frequencies differed among dispersal syndrome groups. The animal dispersal syndrome was significantly more frequent in species with CHR. Our results show an evolutionary convergence of seedling types at the community level worldwide and the existence of a phylogenetic inertia in the evolution of initial seedling morphology. A comparison among eight tropical communities indicated on average that PEF is the most frequent type and CER the least common, although the relative frequency of each seedling type differs among communities, particularly between Neotropical and Paleotropical sites.
Leaf shape and anatomy as indicators of phase change in the grasses: comparison of maize, rice, and bluegrass
Authors: Sylvester Anne W. , Parker‐Clark Vickie , Murray Glen A.
Published: February 2007

Leaf morphology and anatomy during vegetative phase change was compared in bluegrass, rice, and maize. Maize juvenile leaves are coated with epicuticular wax, lack specialized cells, such as trichomes and bulliform cells, and epidermal cell walls stain a uniform purple color. Adult maize leaves are pubescent, lack epicuticular waxes, and have crenulated epidermal cell walls that stain purple and blue. All bluegrass and rice blades are pubescent, coated with epicuticular waxes, and show purple and blue wall staining. In all three grasses, blade width steadily increases at each node until a threshold size is achieved several nodes before reproductive competence is acquired. Blade‐to‐sheath length showed a similar trend of continuous change followed by discontinuous change prior to reproduction. Analysis of leaf development demonstrated that maize primordia initiate more rapidly relative to blade and sheath growth than do either bluegrass or rice. We conclude that leaf shape, as defined by blade width and blade‐to‐sheath ratio, is a reliable indicator of phase, whereas anatomy is not a universal indicator of phase change in the grasses. We speculate that different growth patterns among these grasses may be attributed to changes in the timing of embryonic and postembryonic development.
Genetic structure of three orchid species with contrasting breeding systems using RAPD and allozyme markers
Authors: Sun M. , Wong K. C.
Published: February 2007

Zeuxine gracilis, Zeuxine strateumatica, and Eulophia sinensis are wild orchids with different breeding systems and colonizing abilities. Zeuxine gracilis is an outcrosser with restricted distribution, whereas S. strateumatica is an apomictic colonizer found only in newly available open habitats. Eulophia sinensis is an outcrossing colonizer. This study investigates the levels of genetic variation and patterns of population structure in these wild orchids to provide genetic information for the development of suitable conservation strategies. Lack of allozyme variation was characteristic of all three species, especially in populations of the two colonizing orchids, Z. strateumatica and E. sinensis. More variable markers, randomly amplified polymorphic DNAs (RAPDs), were further employed to characterize population structure of these species. Substantial genetic variation was found at the RAPD loci within populations of Z. gracilis (p = 21.65 ± 15.88%, A = 1.217 ± 0.159, and H = 0.076 ± 0.054) and E. sinensis (p = 17.82 ± 20.97%, A = 1.179 ± 0.209, and H = 0.070 ± 0.084), but little variation existed within populations of Z. strateumatica (p = 2.84 ± 2.58%, A = 1.029 ± 0.026, and H = 0.011 ± 0.011). Regardless of the breeding system, the total gene diversity at the species level was partitioned primarily between populations, as shown by high GST values, in all three species. An extremely high level of population differentiation (GST = 0.924) was found in the apomictic colonizer Z. strateumatica. The patterns of genetic variation in these wild orchids are apparently related to their differences in breeding system and colonizing ability. Different conservation strategies are needed for the long‐term survival of these species.
The effects of a bumble bee nectar robber on plant reproductive success and pollinator behavior
Authors: Maloof Joan E.
Published: February 2007

Interactions between a plant species (Corydalis caseana), a bumble bee nectar robber (Bombus occidentalis), and a bumble bee pollinator (B. appositus) were studied. There were no significant differences between naturally robbed and unrobbed flowers in fruit set or mean seed set per fruit. Plots of C. caseana plants were subjected to treatments of robbing and no robbing using commercially available colonies of B. occidentalis. Robbers did not pollinate the flowers. Pollinator behavior was observed to determine (1) the number of bees attracted to each plot, (2) the number of inflorescences visited in a plot, (3) the number of flowers visited on each inflorescence, and (4) the distance flown between inflorescences. There were no significant differences in the number of inflorescences visited per bee or the number of flowers visited per inflorescence per bee when robbed and unrobbed treatments were compared. Of the parameters measured, only distance flown between inflorescences differed in the robbed and the unrobbed treatments. Bees flew significantly further between inflorescences in the robbed plots than in the unrobbed plots. The results indicate that the nectar robbers have no negative effect on fruit set or seed set in C. caseana and that they may cause increased pollen flow distances by changing the behavior of the pollinator.
Reproductive biology of henequén (Agave fourcroydes) and its wild ancestor Agave Angustifolia (Agavaceae). i. Gametophyte development
Authors: Piven Nickolai M. , Barredo‐Pool Felipe A. , Borges‐Argáez Ileana C. , Herrera‐Alamillo Miguel A. , Mayo‐Mosqueda Alberto , Herrera‐Herrera José L. , Robert Manuel L.
Published: February 2007

The pathways of micro‐ and megagametophyte development in Agave fourcroydes (henequén) and A. angustifolia were studied. We used histology and light microscopy to observe anther ontogeny and ovary differentiation in relation to flower bud size. Both species have the same sexual reproductive strategies and gametophyte development that may be divided into three phases: (1) premeiotic, which includes the establishment of the megaspore mother cell and the pollen mother cell; (2) meiotic, the formation of mature microspores and functional megaspores; (3) postmeiotic, which encompasses the development of mature pollen grains and the formation of the embryo sac. A successive type microsporogenesis was found in both species with formation of T‐shaped tetrads and binuclear pollen grains. In vitro germination tests revealed very low pollen fertility. The female gametophyte is formed from two micropylar megaspore cells after the first meiotic division (bisporic type). Male and female gametogenesis occur asynchronously with microsporogenesis finishing before macrosporogenesis. The results so far show that the formation of male and female gametophytes in henequén is affected at different stages and that these alterations might be responsible for the low fertility shown by this species.
Phylogenetics of Paniceae (Poaceae)
Authors: Duvall Melvin R. , Noll Jeffrey D. , Minn Alexandra H.
Published: February 2007

Paniceae demonstrate unique variability of photosynthetic physiology and anatomy, including both non‐Kranz and Kranz species and all subtypes of the latter. This variability suggests hypotheses of independent origin or reversals (e.g., from C4 to C3). These hypotheses can be tested by phylogenetic analysis of independent molecular characters. The molecular phylogeny of 57 species of Paniceae was explored using sequences from the grass‐specific insert found in the plastid locus rpoC2. Phylogenetic analyses confirmed some long‐recognized alliances in Paniceae, some recent molecular phylogenetic results, and suggested new relationships. Broadly, Paniceae were found to be paraphyletic with Andropogoneae, Panicum was found to be polyphyletic, and Oplismenus hirtellus was resolved as the sister group to the remaining ingroup species. A particularly well‐supported clade in the rpoC2 tree included four genera with non‐Kranz species and three with distinctively keeled paleas. As previously suggested, the PCK (phosphoenol pyruvate carboxykinase) C4 subtype arose once within Paniceae. All clades with non‐Kranz species had Kranz ancestors or sister taxa suggesting repeated loss of the Kranz syndrome.
A molecular phylogenetic study of the subtribe Glycininae (Leguminosae) derived from the chloroplast DNArps16 intron sequences
Authors: Lee Jeongran , Hymowitz Theodore
Published: February 2007

Phylogenetic relationships among 13 genera of the subtribe Glycininae, two genera of the allied subtribe Diocleinae that were included within Glycininae by Polhill, and two genera of the subtribe Erythrininae as outgroups were inferred from chloroplast DNArps16 intron sequence variation. Pairwise sequence divergence values ranged from identity betweenTeramnus mollisandT. micansand betweenT. flexilisandT. labialisto 7.89% betweenPueraria wallichiiandPseudeminia comosaacross all accessions. Phylogenies estimated using parsimony and neighbor‐joining methods revealed that (1) Glycininae is monophyletic ifPachyrhizusandCalopogonium(both Diocleinae) are included within Glycininae; (2) the genusTeramnusis closely related toGlycine, andAmphicarpaeashowed a sister relationship to the clade comprisingTeramnusandGlycine; (3) the expanded Glycininae including two genera of Diocleinae is divided into three branches, temporarily named I (comprising the rest of the examined taxa), II (Pueraria wallichii), and III (Mastersia), but their relationships are equivocal; and (4) the genusPueraria, regarded as a closely related genus toGlycine, is not monophyletic and should be divided into at least four genera (a hypothesis supported previously by Lackey).
Heteroblasty and preformation in mayapple, Podophyllum Peltatum (Berberidaceae): developmental flexibility and morphological constraint
Authors: Jones Cynthia S. , Watson Maxine A.
Published: February 2007

Developmental preformation can constrain growth responses of shoots to current conditions, but there is potential for flexibility in development preceding formation of the preformed organs. Mayapple (Podophyllum peltatum) is strongly heteroblastic, producing rhizome scales, bud scales, and either a single vegetative foliage leaf or two foliage leaves on a sexual shoot. To understand how and when preformation constrains growth responses, we compare (1) how leaf homologs of the renewal shoot differ in development, (2) whether there are differences in shoot development that occur in advance of morphological determination of shoot type, and (3) whether there are points of developmental flexibility in renewal shoot growth prior to preformation of the foliage and floral organs. We use scanning electron microscopy and histology to show that the three vegetative leaves (both types of scale leaves and the vegetative foliage leaf) are similar in the initial establishment of an encircling and overarching leaf base. Differences among them are found in the timing of differentiation of the leaf base and in the relative timing and degree of growth of the lamina and petiole. In contrast, foliage leaves on sexual shoots show less expression of the leaf base and precocious growth of the lamina and petiole. Prior to shoot type determination, there are no morphological differences in the sequence or position of leaf homologs that predict final shoot type. In this colony, leaves at positions 12 and 13, on average, appear to be identical in development until they are between 700 and 800 μm in length, when it becomes possible to distinguish leaves that will become vegetative foliage leaves from additional bud scale leaves on vegetative or sexual shoots. We suggest that late developmental determination of leaves at positions 12 and 13 reflects ontogenetic sensitivity to a transition to flowering. Thus, in mayapple, heteroblasty appears to facilitate developmental flexibility prior to the point where shoot growth becomes constrained by preformation of determined aerial structures.
Hydrophobic trichome layers and epicuticular wax powders in Bromeliaceae
Authors: Pierce Simon , Maxwell Kate , Griffiths Howard , Winter Klaus
Published: February 2007

The distinctive foliar trichome of Bromeliaceae has promoted the evolution of an epiphytic habit in certain taxa by allowing the shoot to assume a significant role in the uptake of water and mineral nutrients. Despite the profound ecophysiological and taxonomic importance of this epidermal structure, the functions of nonabsorbent trichomes in remaining Bromeliaceae are not fully understood. The hypothesis that light reflection from these trichome layers provides photoprotection was not supported by spectroradiometry and fluorimetry in the present study; the mean reflectance of visible light from trichome layers did not exceed 6.4% on the adaxial surfaces of species representing a range of ecophysiological types nor was significant photoprotection provided by their presence. Several reports suggesting water repellency in some terrestrial Bromeliaceae were investigated. Scanning electron microscopy (SEM) and a new technique—fluorographic dimensional imaging (FDI)—were used to assess the interaction between aqueous droplets and the leaf surfaces of 86 species from 25 genera. In the majority of cases a dense layer of overlapping, stellate or peltate trichomes held water off the leaf epidermis proper. In the case of hydrophobic tank‐forming tillandsioideae, a powdery epicuticular wax layer provided water repellency. The irregular architecture of these indumenta resulted in relatively little contact with water droplets. Most mesic terrestrial Pitcairnioideae examined either possessed glabrous leaf blades or hydrophobic layers of confluent trichomes on the abaxial surface. Thus, the present study indicates that an important ancestral function of the foliar trichome in Bromeliaceae was water repellency. The ecophysiological consequences of hydrophobia are discussed.
Response to ammonium and nitrate by a mycorrhizal annual invasive grass and native shrub in southern California
Authors: Yoshida Lidia C. , Allen Edith B.
Published: February 2007

The goal of this study was to determine the interaction of mycorrhizae and two N sources, ammonium (NH4+) and nitrate (NO3−), on the growth of a coastal sage scrub (CSS) species, Artemisia californica, and an exotic annual grass, Bromus madritensis ssp. rubens. Anthropogenic nitrogen deposition may be influencing the decline of CSS and replacement by exotic grasses, but the extent to which mycorrhizae are involved in shrubland decline is unknown. NO3− is the dominant form of deposition in southern California, although the native, uneutrophied soils have a greater concentration of NH4+. Seeds of each species were germinated in pots of sterile soil, inoculated with native soil containing mycorrhizal spores and infective root fragments, and fertilized with 50 μg/g of either NO3− or NH4+. NH4+ enhanced the growth of both mycorrhizal species, while NO3− did not. Control plants of B. madritensis under low N had a significant response to mycorrhizae, but A. californica did not. Nitrate increased the growth of nonmycorrhizal A. californica as much as the mycorrhizal NH4+‐treated plants. There is no evidence in this study to suggest that the decline of A. californica or increase in B. madritensis is due to a mycorrhizal response to NO3−. Other life history traits of the two species must be used to explain the invasive behavior of the annual grass. Mycorrhizae may be more important in controlling plant growth in native uneutrophied soils dominated by NH4+ rather than NO3−.
“Another White Race:” Mexican Americans and the Paradox of Whiteness in Jury Selection
Authors: Sheridan Clare
Published: February 2007

In 1954, seventy-four years after the U.S. Supreme Court held that African Americans could not be banned from jury service by statute, and fifty-four years after it ruled that they could not be purposely excluded from venires due to their “race or color” through court, executive, or administrative action, the Court found that Pete Hernandez had been denied equal protection of the laws under the Fourteenth Amendment. His constitutional rights were violated because of the de facto, systematic exclusion of Mexican Americans from the pool of potential jurors—and thus juries—in Jackson County, Texas.
Brownover “Other White”: Mexican Americans' Legal Arguments and Litigation Strategy in School Desegregation Lawsuits
Authors: Wilson Steven H.
Published: February 2007

The landmark 1954 decisionBrown v. Board of Educationhas shaped trial lawyers' approaches to litigating civil rights claims and law professors' approaches to teaching the law's powers and limitations. The court-ordered desegregation of the nation's schools, moreover, inspired subsequent lawsuits by African Americans aimed variously at ending racial distinctions in housing, employment, and voting rights. Litigation to enforce theBrowndecision and similar mandates brought slow but steady progress and inspired members of various other minorities to appropriate the rhetoric, organizing methods, and legal strategy of the African American civil rights struggle.
Australian Legal Histories in Context
Authors: Hunter Rosemary
Published: February 2007

Australian legal history has only emerged as a field of scholarship in its own right in the last twenty years. Prior to that, Australian legal history tended to be written and taught as a footnote to the great sweep of English legal history—the history of the king's courts, the common law and equity, and major nineteenth-century statutory reforms, with a chapter at the end about the classification of the Australian colonies as “settled” colonies, and the consequent reception of English law. This year (2002) sees the twentieth anniversary of Alex Castles's groundbreaking work An Australian Legal History, the first book to take Australian laws and legal institutions as its entire subject matter. It is also the twentieth anniversary of the first Australian Law and History Conference. The years since 1982 have seen the advent of the Australian and New Zealand Law and History Society, increasing attendances at its annual conferences, the establishment of the Australian Journal of Legal History, the completion of a number of Ph.D.theses in the field, and the publication of further influential texts and edited collections by (among others) the authors of the two articles featured in this forum. Two of the most productive strands in this developing literature have concerned the history of colonization and the dispossession of indigenous peoples and histories of women and gender relations in law, although these are by no means that only areas that have been explored. Running through much of this literature, too, are themes of imperial-colonial relations, and relations between law and colonial economies and societies, particularly prior to federation in 1901.