bluuebunny/crossref_metadata_2025 huggingface dataset:
Transgenic mice expressing small interfering RNA against Gata4 point to a crucial role of Gata4 in the heart and gonads
Authors: Thurisch Boris , Liang Shermi Y , Sarioglu Nanette , Schomburg Lutz , Bungert Jörg , Dame Christof
Published: June 2009

Homozygous deficiency of the transcription factor Gata4 in mice causes lethality due to defects in ventral morphogenesis and heart tube formation. There is increasing evidence demonstrating that GATA4 function is also relevant for normal developed organ systems, including the heart and endocrinum. To analyze the implication of Gata4 beyond development, we generated transgenic mice expressing inducible small interfering RNA against Gata4. In longitudinal analysis, efficient suppression of Gata4 mRNA (down to 80% of wild-type levels) and protein expression in the heart was detected 38 days after induction of Gata4 short hairpin RNA. Decreased Gata4 expression was associated with reduction in the expression of known cardiac target genes, but the function of the heart remained unperturbed at 20–30% of normal Gata4 levels. Interestingly, Gata4 expression was almost abolished in the ovary and testis. This was accompanied in the testis by a significant reduction of GATA4 downstream target genes, such as the genes encoding Mullerian inhibiting substance (MIS) and steroidogenic acute regulatory (StAR) protein. By contrast, expression levels of Mis and Star were only slightly modified in the ovary, and concentrations of circulating FSH and LH were normal in female transgenic mice after induction of Gata4 short hairpin RNA. However, inhibition of Gata4 expression led to the formation of ovarian teratoma in 10% of females. Histology of the teratomas showed predominantly ectodermal and mesodermal structures. Our data demonstrate that Gata4 is critically involved in the function and integrity of the gonads in vivo.
Inhibin βB expression in murine adipose tissue and its regulation by leptin, insulin and dexamethasone
Authors: Hoggard N , Cruickshank M , Moar K M , Barrett P , Bashir S , Miller J D B
Published: June 2009

Inhibin βB (INHBB; coding for the activin βB subunit) has previously been identified in both human and rodent adipose tissue and using Taqman real-time PCR with specific primers we confirm the expression of INHBB mRNA in rodent adipose tissue. Expression of INHBB in murine epididymal adipose tissue was higher than in any of the other tissues studied and appears to be regulated by changes in energy balance and leptin. It was increased fourfold in the epididymal fat depot of ob/ob mice compared with the same fat depot in lean mice. The i.p. administration of leptin in obese ob/ob mice decreases the expression of INHBB. In human adipose tissue, INHBB is reduced by weight loss. In keeping with this, we demonstrate that INHBB expression in murine adipose tissue is decreased in fasting and increased upon refeeding. We show that INHBB is expressed in both the mature adipocyte and the stromal vascular fraction of adipose tissue. INHBB increases with the differentiation of pre-adipocytes into mature adipocytes in the 3T3-L1 cell line. In differentiated 3T3-L1 adipocytes, where receptors to activin have been previously reported, insulin increases the expression of INHBB, while dexamethasone decreases the expression of INHBB when compared with untreated control cells. Taken together, these results suggest that the regulation of INHBB expression in adipose tissue may play a physiological role in energy balance or the insulin insensitivity associated with obesity.
Sex effects on life span and senescence in the wild when dates of birth and death are unknown
Authors: Zajitschek Felix , Brassil Chad E. , Bonduriansky Russell , Brooks Robert C.
Published: June 2009

Males and females allocate and schedule reproductive effort in very different ways. Because the timing and amount of reproductive effort influence survival and thus the optimization of life histories, mortality and senescence are predicted to be sex specific. However, age‐specific mortality rates of wild animals are often difficult to quantify in natural populations. Studies that report mortality rates from natural populations are, therefore, almost entirely confined to long‐lived, easy‐to‐track species such as large mammals and birds. Here, we employ a novel approach using capture–mark–recapture data from a wild population of black field crickets (Teleogryllus commodus) to test for sex differences in demographic aging. In this species, the age of captured adults cannot be readily determined, and animals cannot be reliably captured or observed every night, resulting in demographic data on individuals whose dates of birth and death are unknown. We implement a recently developed life‐table analysis for wild‐caught individuals of unknown age, in combination with a well‐established capture–mark–recapture methodology that models probabilistic dates of death. This unified analytical framework makes it possible to test for aging in wild, hard‐to‐track animals. Using these methods to fit Gompertz models of age‐specific mortality, we show that male crickets have higher mortality rates throughout life than female crickets. Furthermore, males and females both exhibit increasing mortality rates with age, indicating senescence, but the rate of senescence is not sex specific. Thus, observed sex differences in longevity are probably due to differences in baseline mortality rather than aging. Our findings illustrate the complexity of the relationships between sex, background mortality, and senescence rate in wild populations, showing that the elevated mortality rate of males need not be coupled with an elevated rate of aging.
Leaf litter species evenness influences nonadditive breakdown in a headwater stream
Authors: Swan C. M. , Gluth M. A. , Horne C. L.
Published: June 2009

Species loss directly affects the magnitude and stability of various ecosystem processes, and species composition can drive this phenomenon. Much of the evidence that species loss affects ecosystem processes comes from experiments where species richness was manipulated while holding abundance/biomass of individual species constant. Given that species rarely coexist in equal proportions, neglecting evenness might under/overestimate the role of important species combinations. We examined leaf litter breakdown in a small stream based on species‐specific input rates of leaf litter from the four dominant species (Liriodendron tulipifera,Fraxinus pennsylvanica,Fagus grandifolia,Quercus prinus), comprising 71% of inputs over peak leaf fall, for a full‐factorial litter mixture study. Our experimental approach departed from previous mixture studies in that while we created all two‐, three‐, and four‐species combinations holding species‐specific mass constant, we also created a complementary set of mixtures that reflected the natural proportion we estimated from the survey. We found that species richness and evenness alone did not explain variation in breakdown rate, but an interaction between the two did, and mixtures reflecting ambient evenness lost mass nearly 33% faster than single species treatments. Analysis of individual treatments revealed that the emergent effect of mixing species was nearly twice as common in uneven vs. even mixtures. The compositional effects of litter diversity on breakdown uncovered in previous studies might be more pronounced if evenness, and not just richness, is considered when evaluating the role of species loss in these ecosystems.
Scale and the isotopic record of C4 plants in pedogenic carbonate: from the biome to the rhizosphere
Authors: Monger H. Curtis , Cole David R. , Buck Brenda J. , Gallegos Robert A.
Published: June 2009

The 13C/12C ratio in pedogenic carbonate (i.e., CaCO3 formed in soil) is a significant tool for investigating C4 biomes of the past. However, the paleoecological meaning of δ13C values in pedogenic carbonate can change with the scale at which one considers the data. We describe studies of modern soils, fossil soils, and vegetation change in the Chihuahuan Desert of North America and elsewhere that reveal four scales important for paleoecologic interpretations. (1) At the broadest scale, the biome scale (hundreds to millions of km2), an isotopic record interpreted as C3 vegetation replacing C4 grasslands may indicate invading C3 woody shrubs instead of expanding C3 forests (a common interpretation). (2) At the landscape scale (several tens of m2 to hundreds of km2), the accuracy of scaling up paleoclimatic interpretations to a regional level is affected by the landform containing the isotopic record. (3) At the soil‐profile scale (cm2 to m2), soil profiles with multiple generations of carbonate mixed together have a lower‐resolution paleoecologic record than soil profiles repeatedly buried. (4) At the rhizosphere scale (μm2 to cm2), carbonate formed on roots lack the 14–17‰ enrichment observed at broader scales, revealing different fractionation processes at different scales. A multi‐scale approach in dealing with δ13C in pedogenic carbonate will increase the accuracy of paleoecologic interpretations and understanding of soil–geomorphic–climatic interactions that affect boundaries between C4 and C3 vegetation.
Seasonal source–sink dynamics at the edge of a species' range
Authors: Kanda L. Leann , Fuller Todd K. , Sievert Paul R. , Kellogg Robert L.
Published: June 2009

The roles of dispersal and population dynamics in determining species' range boundaries recently have received theoretical attention but little empirical work. Here we provide data on survival, reproduction, and movement for a Virginia opossum (Didelphis virginiana) population at a local distributional edge in central Massachusetts (USA). Most juvenile females that apparently exploited anthropogenic resources survived their first winter, whereas those using adjacent natural resources died of starvation. In spring, adult females recolonized natural areas. A life‐table model suggests that a population exploiting anthropogenic resources may grow, acting as source to a geographically interlaced sink of opossums using only natural resources, and also providing emigrants for further range expansion to new human‐dominated landscapes. In a geographical model, this source–sink dynamic is consistent with the local distribution identified through road‐kill surveys. The Virginia opossum's exploitation of human resources likely ameliorates energetically restrictive winters and may explain both their local distribution and their northward expansion in unsuitable natural climatic regimes. Landscape heterogeneity, such as created by urbanization, may result in source–sink dynamics at highly localized scales. Differential fitness and individual dispersal movements within local populations are key to generating regional distributions, and thus species ranges, that exceed expectations.
Reliable cues and signals of fruit quality are contingent on the habitat in black elder (Sambucus nigra)
Authors: Schaefer H. Martin , Braun Julius
Published: June 2009

Communication mediates interactions between organisms and can be based on signals or cues. Signals are selected for their signaling function, whereas cues evolve for reasons other than signaling. To be evolutionarily stable, communication needs to be reliable on average, but the mechanisms that enforce reliability are hotly debated in light of strong environmental influence on signals and cues. While fruit quality in black elder (Sambucus nigra) is unrelated to fruit color, it is indicated by alternative pedicel phenotypes. Information on fruit quality has thus been transferred from the fruit to the developmentally associated pedicels, which are environmentally determined cues. Within each phenotype, color variation indicates fruit quality. Communication by black elder is thus reliable, but the proximate mechanisms enforcing reliability are habitat specific. High irradiance increases both the contrasts of the visual cue and fruit quality in the anthocyanin‐based red pedicel phenotype, while shaded plants of the chlorophyll‐based green phenotype apparently use signals by forgoing photosynthesis. This is because lower chlorophyll content in green pedicels creates contrasting pedicels, and higher contrasts indicate higher sugar content in the fruits of green pedicels. Because anthocyanins are light‐induced, plants use cues when exposed to high irradiance, whereas they apparently use costly signals in the shade by reducing chlorophyll content in the pedicels. In behavioral field and laboratory experiments we document that avian seed dispersers select among pedicel phenotypes that indicate different fruit quality. Plants can thus increase their reproductive success by sending highly informative cues. Our results indicate how reliable information transfer can be maintained both in cues and signals in spite of substantial environmental influence on visual traits.
Temporal variability and nestedness in California grassland species composition
Authors: Elmendorf Sarah C. , Harrison Susan P.
Published: June 2009

Nestedness occurs when species‐poor assemblages contain a subset of the species that occur in more species‐rich communities and is a commonly observed pattern in spatial data sets. Examination of nested distribution patterns across time rather than space are rarely conducted, even though they may have important implications for species coexistence. Nested temporal assemblages can occur when most species respond similarly to interannual variation in conditions. In contrast, assemblages might be non‐nested when different sets of species occur in different years, either because of different resource requirements or as a result of competitive exclusion. Using eight years of plant occurrence data at 71 sites in California grasslands, we found strong signals of temporal nestedness with most species favored by similar conditions. High‐quality years enabled the expansion of both grasses and forbs into locales where they were not found during poor‐quality years. Native annual forb, exotic annual forb, and exotic annual grass species richness were all greatest in cool, wet years following hot, dry years. Together, these analyses support the hypothesis that, in the absence of community members that specialize on poor‐quality years, interannual environmental variation can cause communities to form nested subsets across time much as they do across space.
Assessing evidence of phase shifts from coral to macroalgal dominance on coral reefs
Authors: Bruno John F. , Sweatman Hugh , Precht William F. , Selig Elizabeth R. , Schutte Virginia G. W.
Published: June 2009

Many marine scientists have concluded that coral reefs are moving toward or are locked into a seaweed‐dominated state. However, because there have been no regional‐ or global‐scale analyses of such coral reef “phase shifts,” the magnitude of this phenomenon was unknown. We analyzed 3581 quantitative surveys of 1851 reefs performed between 1996 and 2006 to determine the frequency, geographical extent, and degree of macroalgal dominance of coral reefs and of coral to macroalgal phase shifts around the world. Our results indicate that the replacement of corals by macroalgae as the dominant benthic functional group is less common and less geographically extensive than assumed. Although we found evidence of moderate local increases in macroalgal cover, particularly in the Caribbean, only 4% of reefs were dominated by macroalgae (i.e., >50% cover). Across the Indo‐Pacific, where regional averages of macroalgal cover were 9–12%, macroalgae only dominated 1% of the surveyed reefs. Between 1996 and 2006, phase shift severity decreased in the Caribbean, did not change in the Florida Keys and Indo‐Pacific, and increased slightly on the Great Barrier Reef due to moderate coral loss. Coral reef ecosystems appear to be more resistant to macroalgal blooms than assumed, which has important implications for reef management.
What drives long‐distance dispersal? A test of theoretical predictions
Authors: Lowe Winsor H.
Published: June 2009

Long‐distance dispersal (LDD) may contribute disproportionately to species persistence in fragmented landscapes, non‐native invasions, and range shifts in response to climate change. However, direct data on LDD are extremely limited, leaving us with little understanding of why it occurs. I used six years of mark–recapture data on the stream salamanderGyrinophilus porphyriticusto test theoretical predictions of how variation in habitat quality affects LDD. Frequency of LDD was quantified using the kurtosis of yearly movement distributions from recaptured animals in a 1‐km headwater stream. Temporal and spatial variation in habitat quality were quantified with spatially explicit data on the body condition and dispersion of individuals throughout the study stream. Using information‐theoretic model selection criteria, I found that LDD increased during periods of low average body condition and low spatial variation in body condition. Consistent with basic theory, my results indicate that temporal variation in habitat quality is critical to initiating dispersal, and that LDD increases when animals must move farther to encounter higher‐quality habitat. This suggests that information on how habitat quality varies in time and space can be useful for predicting LDD. More broadly, this study highlights the value of direct data on animal movement for testing dispersal theory.
The insect immune response and other putative defenses as effective predictors of parasitism
Authors: Smilanich Angela M. , Dyer Lee A. , Gentry Grant L.
Published: June 2009

Parasitic wasps and flies (parasitoids) exert high mortality on caterpillars, and previous studies have demonstrated that most primary and secondary defenses do not protect caterpillars against parasitoids. We investigated the efficacy of tertiary defenses (i.e., immune responses) against parasitoids. Using a bead injection technique to measure the immune response and a 15‐year database to measure parasitism, we compared the immune response for 16 species of caterpillars in nine different families. We found that caterpillar species with a strong immune response had the lowest incidence of parasitism, and when statistically compared to other defensive traits, the immune response was the best predictor of parasitism. Parasitoids either avoid attacking caterpillar species with a capacity for high levels of melanization or are killed once they have parasitized. In either case, the immune response is clearly one of the most effective defenses that caterpillars have against parasitism, and elucidating consistent predictors of variation in encapsulation could improve understanding of parasitism patterns in time and space and could enhance biological control efforts.
Complexity in quantitative food webs
Authors: Banašek-Richter Carolin , Bersier Louis-Félix , Cattin Marie-France , Baltensperger Richard , Gabriel Jean-Pierre , Merz Yves , Ulanowicz Robert E. , Tavares Annette F. , Williams D. Dudley , Ruiter Peter Cde , Winemiller Kirk O. , Naisbit Russell E.
Published: June 2009

Food webs depict who eats whom in communities. Ecologists have examined statistical metrics and other properties of food webs, but mainly due to the uneven quality of the data, the results have proved controversial. The qualitative data on which those efforts rested treat trophic interactions as present or absent and disregard potentially huge variation in their magnitude, an approach similar to analyzing traffic without differentiating between highways and side roads. More appropriate data are now available and were used here to analyze the relationship between trophic complexity and diversity in 59 quantitative food webs from seven studies (14–202 species) based on recently developed quantitative descriptors. Our results shed new light on food‐web structure. First, webs are much simpler when considered quantitatively, and link density exhibits scale invariance or weak dependence on food‐web size. Second, the “constant connectance” hypothesis is not supported: connectance decreases with web size in both qualitative and quantitative data. Complexity has occupied a central role in the discussion of food‐web stability, and we explore the implications for this debate. Our findings indicate that larger webs are more richly endowed with the weak trophic interactions that recent theories show to be responsible for food‐web stability.
Wastewater disinfection and organic matter removal using ferrate (VI) oxidation
Authors: Bandala Erick R. , Miranda Jocelyn , Beltran Margarita , Vaca Mabel , López Raymundo , Torres Luis G.
Published: June 2009

The use of iron in a +6 valence state, (Fe (VI), as FeO4−2) was tested as a novel alternative for wastewater disinfection and decontamination. The removal of organic matter (OM) and index microorganisms present in an effluent of a wastewater plant was determined using FeO4−2 without any pH adjustment. It was observed that concentrations of FeO4−2 ranging between 5 and 14 mg l−1 inactivated up to 4-log of the index microorganisms (initial concentration c.a. 106 CFU/100 ml) and achieved OM removal up to almost 50%. The performance of FeO4−2 was compared with OM oxidation and disinfection using hypochlorite. It was observed that hypochlorite was less effective in OM oxidation and coliform inactivation than ferrate. Results of this work suggest that FeO4−2 could be an interesting oxidant able to deactivate pathogenic microorganisms in water with high OM content and readily oxidize organic matter without jeopardizing its efficiency on microorganism inactivation.
Validation of urinary trichloroacetic acid as a biomarker of exposure to drinking water disinfection by-products
Authors: Zhang Weiping , Gabos Stephan , Schopflocher Donald , Li Xing-Fang , Gati Wendy P. , Hrudey Steve E.
Published: June 2009

Disinfection by-products (DBPs) in drinking water represent a public health issue and a challenge for epidemiology to provide evidence towards the causation of various hypothesized health effects. Validation of a biomarker of exposure to DBPs is a strategy to achieve progress which has been advocated. The objective of this study was to validate urinary trichloroacetic acid (TCAA) excretion as a biomarker of exposure to DBPs in an experimental exposure cohort. A total of 52 healthy women participated in the study. Participants consumed supplied tap water for 15 d and provided urine and blood samples for TCAA measurements. The findings revealed that (1) background levels of TCAA in urine and blood were readily detectable, (2) TCAA levels in blood and urine increased with increased amounts of TCAA ingested, (3) the correlations between measurements of TCAA ingestion and urinary excretion were modest (r=0.66, p<0.001) based on one days' sampling and high (r=0.77–0.83, p<0.001) based on two to four days' sampling, (4) the correlations between measurements of TCAA ingestion and blood TCAA concentration were high (r=0.80, p<0.001) and (5) multiple days' urinary TCAA measures improved the prediction of TCAA ingestion through urinary TCAA excretion. TCAA can be a valid biomarker of exposure for DBPs in drinking water.
Bacteriological analysis of indoor and outdoor water parks in Wisconsin
Authors: Davis Tracynda L. , Standridge Jon H. , Degnan Alan J.
Published: June 2009

Water parks are a rapidly growing element of the United States tourist industry. To reduce incidence of abrasion and impact injuries in such parks, designers are searching for padding materials that can withstand the harsh oxidative environments of chlorinated water. Although padded features help reduce physical injuries, they may also compromise the microbiological safety of water attractions. This study describes bacteriological testing performed on 31 different pad materials, play features and pools from 10 Wisconsin water parks. Materials and surrounding pool waters were sampled and tested quantitatively for total coliforms, Escherichia coli, E. coli 0157:H7, enterococci, staphylococci, heterotrophic bacteria, and Pseudomonas aeruginosa, using standard methods. Each location was sampled during three visits, and results were averaged. Pool waters were within acceptable levels of target organisms and disinfectant residuals, but target organisms were found on water features, even those submerged in chlorinated water. Bacteria were detected more frequently in pools using pad materials compared with pools without. These findings provide data that will help the public health community understand the relations between designs, materials and maintenance of water features. Additionally, the information will help state regulators and owner/operators develop guidelines to improve public health and safety at water parks.
A study of the use and impacts of LifeStraw™ in a settlement camp in southern Gezira, Sudan
Authors: Elsanousi Salwa , Abdelrahman Samira , Elshiekh Ibtisam , Elhadi Magda , Mohamadani Ahmed , Habour Ali , ElAmin Somaia E. , Elnoury Ahmed , Ahmed Elhadi A. , Hunter Paul R.
Published: June 2009

This paper reports a study of the LifeStraw™ in El-Masraf camp within Gezira State, Sudan. A total of 647 eligible subjects participated in the study. Two week incidence of diarrhoeal rates were estimated by a community survey some four months before and again four months after provision of the LifeStraw™. In addition counts were kept of people attending at the community clinic with diarrhoea. Compliance rates were good with 86.5% of people saying they always used it and only 3.7% saying they had never used it. In a before implementation survey 15.3% of participants reported diarrhoea in the previous 2 weeks compared with only 2.3% in a survey after implementation. Similarly 58 people presented to the clinic as a new case of diarrhoea in the four months before compared with only six in the four months after implementation. When compared with diarrhoeal attendances at the regional hospital, this was a statistically significant decline in attendances (p<0.0001). The LifeStraw™ is likely to find a role as an adjunct to water quality interventions aimed at the home. However, more research is needed to assess the long-term impact and uptake of these devices before their definitive value can be assessed.
Turbidity and chlorine demand reduction using locally available physical water clarification mechanisms before household chlorination in developing countries
Authors: Kotlarz Nadine , Lantagne Daniele , Preston Kelsey , Jellison Kristen
Published: June 2009

Over 1.1 billion people in the world lack access to improved drinking water. Diarrhoeal and other waterborne diseases cause an estimated 1.9 million deaths per year. The Safe Water System (SWS) is a proven household water treatment intervention that reduces diarrhoeal disease incidence among users in developing countries. Turbid waters pose a particular challenge to implementation of SWS programmes; although research shows that a 3.75 mg l−1 sodium hypochlorite dose effectively treats turbid waters, users sometimes object to the strong chlorine taste and prefer to drink water that is more aesthetically pleasing. This study investigated the efficacy of three locally available water clarification mechanisms—cloth filtration, settling/decanting and sand filtration—to reduce turbidity and chlorine demand at turbidities of 10, 30, 70, 100 and 300 NTU. All three mechanisms reduced turbidity (cloth filtration −1–60%, settling/decanting 78–88% and sand filtration 57–99%). Sand filtration (P=0.002) and settling/decanting (P=0.004), but not cloth filtration (P=0.30), were effective at reducing chlorine demand compared with controls. Recommendations for implementing organizations based on these results are discussed.
Involvement of Nucleotide Excision and Mismatch Repair Mechanisms in Double Strand Break Repair
Authors: Zhang Ye , Rohde Larry H. , Wu Honglu
Published: June 2009

Living organisms are constantly threatened by environmental DNA-damaging agents, including UV and ionizing radiation (IR). Repair of various forms of DNA damage caused by IR is normally thought to follow lesion-specific repair pathways with distinct enzymatic machinery. DNA double strand break is one of the most serious kinds of damage induced by IR, which is repaired through double strand break (DSB) repair mechanisms, including homologous recombination (HR) and non-homologous end joining (NHEJ). However, recent studies have presented increasing evidence that various DNA repair pathways are not separated, but well interlinked. It has been suggested that non-DSB repair mechanisms, such as Nucleotide Excision Repair (NER), Mismatch Repair (MMR) and cell cycle regulation, are highly involved in DSB repairs. These findings revealed previously unrecognized roles of various non-DSB repair genes and indicated that a successful DSB repair requires both DSB repair mechanisms and non-DSB repair systems. One of our recent studies found that suppressed expression of non-DSB repair genes, such as XPA, RPA and MLH1, influenced the yield of IRinduced micronuclei formation and/or chromosome aberrations, suggesting that these genes are highly involved in DSB repair and DSB-related cell cycle arrest, which reveals new roles for these gene products in the DNA repair network. In this review, we summarize current progress on the function of non-DSB repair-related proteins, especially those that participate in NER and MMR pathways, and their influence on DSB repair. In addition, we present our developing view that the DSB repair mechanisms are more complex and are regulated by not only the well known HR/NHEJ pathways, but also a systematically coordinated cellular network.
Network Evolution: The Origins of Structural Holes
Authors: Zaheer Akbar , Soda Giuseppe
Published: June 2009

We develop and test a theory of the origins of network structures, specifically of structural holes, building and testing a theoretical framework proposing that network structures emerge from the interplay of two complementary forces: structural constraints and network opportunities. We analyze data on a co-membership network among 501 production teams in the Italian TV production industry tracked over a period of 12 years, explicitly accounting for endogeneity. We find that structural holes spanned by teams originate from the prior status and centrality of teams that members were part of in the past, in addition to structural holes spanned in the past. But a focal team spans fewer structural holes if its members were part of cohesive teams earlier and if the past teams they were connected to produced similar artistic content. We also demonstrate that spanning structural holes is associated with superior team performance in terms of greater viewership. The results support both opportunity exploitation and structural constraint explanations, although we find that homogeneity rather than diversity influences performance across structural holes.
Tilting at Windmills? The Environmental Movement and the Emergence of the U.S. Wind Energy Sector
Authors: Sine Wesley D. , Lee Brandon H.
Published: June 2009

Through a study of the emergent U.S. wind energy sector, 1978–1992, this paper examines how large-scale social movements external to an industry can influence the creation of new market opportunities and hence encourage entrepreneurship. We theorize that through the construction and propagation of cognitive frameworks, norms, values, and regulatory structures, and by offering a preexisting social structure, social movement organizations influence whether entrepreneurs attempt to start ventures in emerging sectors. We find that the direct and indirect effects of social resources (e.g., environmental groups) had a larger impact on entrepreneurial activity in this sector than the availability of natural resources such as land with high-quality wind. Greater numbers of environmental movement organization members increased nascent entrepreneurial activity, and this effect was mediated by favorable state regulatory policy. Greater membership numbers also enhanced the effects of important natural resources, market conditions, and skilled human capital on entrepreneurial activity. Taken together, these results have important implications for the study of social movements, entrepreneurship, and institutional theory.
Who Does an Elite Organization Emulate?
Authors: Still Mary C. , Strang David
Published: June 2009

We advance theories of the diffusion of innovations by examining the structure of emulation that emerged in one bank's benchmarking program. Prestigious firms and firms linked to the bank through executive migration were disproportionately likely to be recruited as benchmarking partners and, once visited, to be highly influential. Firms tied to the bank by board interlocks and geographic proximity were neither overrepresented nor influential. The bank also paid modest attention to other financial service providers, particularly rival money centers. These relationships hold net of area-specific recognition for excellence, which promotes attention but not influence, and financial performance, which affects neither. We emphasize the way organizational identity and decision-making processes activate and deactivate network ties as potential channels of innovation diffusion.
Networks, Propinquity, and Innovation in Knowledge-intensive Industries
Authors: Whittington Kjersten Bunker , Owen-Smith Jason , Powell Walter W.
Published: June 2009

Industrial districts and regional clusters depend on the networks that arise from reciprocal linkages among co-located organizations, while physical proximity among firms can alter the nature of information and resource flows through networks. We consider the joint effects of geographic propinquity and network position on organizational innovation using negative binomial count models of patenting activity for U.S.-based life science firms in industrial districts and regional clusters across a 12-year time period, 1988–1999. We find evidence that regional agglomeration and network centrality exert complementary, but contingent, influences on organizational innovation. Results show that in the high-velocity, research-intensive field of biotechnology, geographic and network positions have both independent and contingent effects on organizational innovation. The influence of centrality in local, physically co-located partner networks depends on the extent to which firms are also embedded in a global network comprising physically distant partners. Such global centrality, however, alters how proximity to two important classes of organization-other biotechnology firms and public sector research organizations, such as universities, research institutes, and teaching hospitals—influences innovation. Regional agglomeration shapes the character of information and resource flows through networks, while much of what makes industrial clusters region-like involves the structure of their internal networks. We conclude that network effects persist both independently and interdependently with geographic variables, and regional characteristics influence the degree to which centrality enhances innovation.
Quality of Grandparent-Grandchild Relationship in Asian-Indian Immigrant Families
Authors: Saxena Divya , Sanders Gregory F.
Published: June 2009

A sample of 112 Asian-Indian Immigrant grandchildren, age 10–16 years, from different parts of the United States completed survey questionnaires regarding the quality of relationship with their grandparents in India. The study explored the factors that affected the quality of relationship between two different generations living at considerable geographical distance and in different cultures. Findings indicated that role importance, amount of contact, and health of the grandparent uniquely contributed to the relationship quality. Results also indicated acculturation was not a significant predictor of relationship quality, although it was a significant predictor of role importance. Limitations to the study relative to acculturation scores and sampling are discussed and further research should address these limitations and the grandparent-parent relationship. Implications include adopting a tri-generational perspective in future studies and practice.
Fourier Transform Infrared Spectroscopy of Geological and Archaeological Chert from Southern Ontario
Authors: Hawkins Alicia L. , Tourigny Eric , Long Darrel G. F. , Julig Patrick J. , Bursey Jeffery
Published: June 2009

Fourier transform infrared spectroscopy (FT-IR) may provide a low-cost, minimally destructive method for sourcing archaeological cherts in Ontario. In this article we outline a study to characterize chert samples from geological sources in Ontario and to identify the raw material of a small number of archaeological specimens from the late sixteenth century A.D. Neutral Iroquoian Emmerson Springs site. We compare our results with those from an earlier study that used FT-IR to determine if cherts selected for excellent knapping qualities contain sufficient trace minerals to allow for accurate source characterization.
Pelham Prase—A Local Connecticut Valley Lithic Resource
Authors: Pretola John P.
Published: June 2009

In the Northeast, studies of lithic trade have sometimes obscured the importance of local lithic resources. Local materials may be misidentified as trade items or simply placed in the miscellaneous category. This article documents a local Connecticut Valley chert mineral much favored in the Woodland Period for thumbnail scrapers at the Quinnetuck Narrows Site, Gill, Massachusetts. Both X-ray diffraction and optical mineralogy techniques identify this as a circumscribed local chert that is unprecedented for being located in a heavily metamorphosed terrain. Outcrops, glacial boulders, and stream cobbles probably provided ready access to this material in the local area.
Instrumental Neutron Activation Analysis of Middle Woodland Pottery from the Delaware Valley
Authors: Pevarnik George L. , Boulanger Matthew T. , Glascock Michael D.
Published: June 2009

One hundred nineteen late Middle Woodland (ca. A.D. 200–900) sherds and 10 clay samples from the Lower/Middle Delaware Valley were analyzed by Instrumental Neutron Activation Analysis. Principal components analysis resulted in the preliminary identification of 8 compositional groups. Two of these groups ( n = 42) and Piedmont-derived clay samples ( n = 4) are noteworthy because they exhibit markedly higher sodium concentrations in relation to the full dataset. Given this observed difference in sodium content, we conclude that the Piedmont is the likely source/production area for this subset of sherds. The relatively high sodium content present in the clays from the Piedmont reinforces the conclusion that the reported sodium values are the result of geologic origin and not diagenetic processes. These results are also used to evaluate an existing late Middle Woodland settlement model for the Lower/Middle Delaware Valley (Stewart, 1990, 1998a, 1998b). However, until further testing is conducted, these interpretations must be viewed as tentative.
Geographic and Compositional Variability of Ceramic Resources in Northern New England
Authors: Boulanger Matthew T. , Glascock Michael D.
Published: June 2009

Approaches to ceramic analysis in northern New England have historically followed a normative approach to describing form and decoration. Further, these analyses have, with few exceptions, been limited to addressing questions of culture history and chronology. Recent analysis of pottery from the Woodland and Contact periods as well as natural clay deposits from Vermont and New Hampshire serves as a case study in how regional archaeologists may move beyond simplistic questions of “Who?” and “When?” and begin to pursue the “How?” and “Why?” To that end, these data are discussed in terms of technological choices and transmission of cultural knowledge across generations.
Blue Vivianite in Prehistoric Clay
Authors: Dillian Carolyn , Bello Charles
Published: June 2009

Experiments have demonstrated that vivianite, when processed using heat, produces a vivid blue pigment that could have been used as body paint, yet this vivid blue pigment could have been utilized in other ways as well. Archaeologically, vivianite has been documented as a component of clay pottery, but this vivianite was part of the clay matrix, not applied to the surface of the vessel. Experiments designed to assess the utility of vivianite as a blue colorant to a prehistoric ceramic matrix are outlined here. Clay pellets were painted with a vivianite slip and alternately had vivianite added to the clay prior to drying. Contrary to expected results, this vivianite, when mixed with clay or applied to the surface, does not yield a vivid blue color with heating. As a result, we must assume that vivianite may have merely been an accidental inclusion in the clay matrix as documented archaeologically, perhaps as a naturally occurring component of the original clay source or tempering material.
The Growth of Death Awareness through Death Education among University Students in Hong Kong
Authors: Wong Wai-Ying
Published: June 2009

This study attempts to explore the attitude toward death, which ranges from fear of death to its acceptance, held by students of one of the universities in Hong Kong. It also tries to examine the relationship between their attitude toward death and their ratings of life and death. Another aim of this study is to evaluate the efficacy of a death education course offered in that university. It is found that the present death attitude of Hong Kong university students is not satisfactory and that it has been significantly improved after students took a death education course.
Removal of mineral oil and wastewater pollutants using hard coal
Authors: Simonovic Branislav , Arandjelovic Dragana , Jovanovic Mica , Kovacevic Branimir , Pezo Lato , Jovanovic Aca
Published: June 2009

This study investigates the use of hard coal as an adsorbent for removal of mineral oil from wastewater. In order to determine the efficiency of hard coal as an adsorbent of mineral oil, process parameters such as sorption capacity (in static and dynamic conditions), temperature, pH, contact time, flow rate, and chemical pretreatment were evaluated in a series of batch and continuous flow experiments. There were significant differences in the mineral oil removal for various pH values examined. The adsorption of mineral oil increased as pH values diverged from 7 (neutral). At lower temperatures, the adsorption was notably higher. The wastewater flow rate was adjusted to achieve optimal water purification. Equilibrium was reached after 10 h in static conditions. At that time, more than 99% of mineral oil had been removed. At the beginning of the filtering process, the adsorption rate increased rapidly, only to show a minor decrease afterwards. Equilibrium data were fitted to Freundlich models to determine the water-hard coal partitioning coefficient. Physical adsorption caused by properties of the compounds was the predominant mechanism in the removal process.
Kinetic study of the sorption process with Cu(II) ions on clinoptilolite and analcime: Effects of temperature and particle size
Authors: Cobzaru Claudia , Cibotaru Cristina , Rotariu Adriana , Marinoiu Adriana , Oprea Spiridon
Published: June 2009

The sorption process of the Cu(II) ions on the clinoptilolite and analcime containing volcanic tuff was studied at different temperatures like 40, 60 and 80?C. The effects of temperature and a particle size on the sorption capacity of the used zeolites were analyzed.
Spectrophotometric determination of nicradipine and isradipine in pharmaceutical formulations
Authors: Al-Ghannam S.M. , Al-Olyan A.M.
Published: June 2009

A sensitive spectrophotometric method was developed for the determination of some 1,4-dihydropyridine compounds namely, nicardipine and isradipine either in pure form or in pharmaceutical preparations. The method is based on the reduction of nicardipine and isradipine with zinc powder and calcium chloride followed by further reduction with sodium pentacyanoaminoferrate (II) to give violet and red products having the absorbance maximum at 546 and 539 nm with nicardipine and isradipine, respectively. Beer's law was obeyed over the concentration range 8.0-180 ?g/ml with the detection limit of 1.67 ?g/ml for nicardipine and 8.0-110 ?g/ml with the detection limit of 1.748 ?g/ml for isradipine. The analytical parameters and their effects on the reported methods were investigated. The molar absorptivity, quantization limit, standard deviation of intercept (Sa), standard deviation of slope (Sb) and standard deviation of the residuals (Sy/x) were calculated. The composition of the result compounds were found 1:1 for nicardipine and 1:2 for isradipine by Job's method and the conditional stability constant (Kf) and the free energy changes (?G) were calculated for compounds formed. The proposed method was applied successfully for the determination of nicardipine and isradipine in their dosage forms. The results obtained were in good agreement with those obtained using the reference or official methods. A proposal of the reaction pathway was presented.
Permeability studies of Damar Batu free films for transdermal application
Authors: Mundada Atish , Avari Jasmine
Published: June 2009

Damar Batu (DB) looks like stone with black or dark brown color inside. Due to its film forming ability it is used in the manufacture of paper, wood, varnishes, lacquers, polishes and additives for beverages. In the present study the permeability of free films of DB casted from chloroform solution containing different plasticizers was studied with a view to developing a suitable rate controlling membrane for transdermal use. The free films of DB were prepared by a mercury substrate technique and dibutyl sebacate (DBS), dibutyl phthalate (DBP), polyethylene glycol 400 (PEG400) and propylene glycol (PG) were tried as plasticizers. DB films were then evaluated for uniformity of thickness, moisture absorption, water vapour transmission, tensile strength, percentage elongation and folding endurance. Permeability characteristics of free films of DB were studied using diltiazem hydrochloride (DH) as a model drug. Little variation in film thickness ensured the uniformity of the films. DBS produces tough DB films with more tensile strength. Drug diffusion through the free films followed zero order kinetics. The films plasticized with PEG400 showed higher permeability for DH compared with other films. The order of decrease of permeability of plasticized films with plasticizers was PEG400 > PG > DBP > DBS. Diffusion of drugs through the free films of DB was extended over a longer period of time at a controlled rate. DB seems to be a promising rate controlling membrane for the transdermal application.
Isolation and characterization of the 68 kD allergen from house dust mite Dermatophagoides pteronyssinus
Authors: Milovanovic Katarina , Burazer Lidija , Vuckovic Olga , Atanaskovic-Markovic Marina , Cirkovic-Velickovic Tanja , Jankov Ratko , Gavrovic-Jankulovic Marija
Published: June 2009

House dust mites (HDM) represent a major source of allergens, contributing to the increasing incidence of type I hypersensitivity disease worldwide. Over 30 different IgE-binding proteins from the HDM extract were detected. Although group 1 and 2 have been identified as major allergens, due to the safety and efficacy of allergy diagnosis and immunotherapy, there is a need to carefully evaluate the clinical relevance of other allergens present in the HDM extract. In regard to this, a high molecular mass allergen of about 68 kD was purified from the HDM extract using a combination of gel permeation chromatography and reversed-phase chromatography. The IgG and IgE reactivity of the purified protein were preserved during the purification process, as confirmed by Western blot analysis with polyclonal rabbit antibodies and dot blot analysis with a pool of sera from subjects with house dust mite allergy, respectively. In addition, the IgE reactivity was confirmed using ELISA testing with nine patient sera. The biological potency of the 68 kD allergen was confirmed by skin prick testing in five allergic subjects, suggesting that the high molecular mass allergen is a good candidate for component-resolved diagnosis of house dust mite allergy and eventual therapeutic treatment.