bluuebunny/crossref_metadata_2025 huggingface dataset:
Intraductal carcinosarcoma with a heterologous mesenchymal component originating in intraductal papillary-mucinous carcinoma (IPMC) of the pancreas with both carcinoma and osteosarcoma cells arising from IPMC cells
Authors: Okamura Jun , Sekine Shigeki , Nara Satoshi , Ojima Hidenori , Shimada Kazuaki , Kanai Yae , Hiraoka Nobuyoshi
Published: March 2010

Carcinosarcoma of the pancreas is extremely rare and its histogenesis is still unclear. This is a report on a 64-year-old female patient with an intraductal carcinosarcoma arising from intraductal papillary-mucinous carcinoma (IPMC) in the pancreas tail. The carcinosarcoma grew as a polypoid mass within the main pancreatic duct. Histologically, the tumour consisted of adenocarcinoma covering the luminal surface of the lesion with minimal stromal invasion, and osteosarcoma occupying the stroma. Immunohistochemical and gene mutation analyses revealed that both the carcinomatous and sarcomatous tumour cells of the carcinosarcoma, as well as the IPMC cells, expressed TP53 and had identical mutations inKRASandTP53genes, indicating that these two neoplastic components of the carcinosarcoma shared a common tumorigenesis and arose from the IPMC. This is the first report of a carcinosarcoma originating in IPMC. These findings imply that carcinosarcoma with a heterologous mesenchymal component is of ductal origin.
The clinicopathological characteristics of ‘triple-negative’ epithelial ovarian cancer
Authors: Liu Naifu , Wang Xingwu , Sheng Xiugui
Published: March 2010

Background

‘Triple-negative’ is traditionally used to define a specific subtype of breast cancer with negative oestrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor-type 2 (HER2) expressions. ER/PR and HER2 testing is also widely used in the informative classification of ovarian cancer.

Aim

To investigate whether a ‘triple-negative’ subtype also exists in ovarian cancer.

Methods

ER, PR and HER2 expressions in 116 Chinese women with primary epithelial ovarian cancer were reviewed. Triple-negative epithelial ovarian cancer (TNEOC) was defined based on negative ER, PR and HER2 expression. The clinicopathological characteristics and Ki-67, P53 and epidermal growth factor receptor (EGFR) expression in the TNEOC and non-TNEOC group were compared.

Results

15.5% of cases (18/116) were identified as TNEOC among 116 ovarian carcinomas. Histological grade 3 was found in a higher percentage of the TNEOC than of the non-TNEOC group (94.4% vs 62.2%). TNEOC also correlated with a high level of Ki-67 and p53 expression. EGFR overexpression and other clinicopathological characteristics were not significantly associated with TNEOC subtype. TNEOC was associated with a shorter progression free survival and overall survival in univariate and multivariate analyses.

Conclusions

A novel subtype of ovarian carcinoma, which is negative for ER, PR and HER2 expression, has been identified; this specific ovarian subtype tends to have aggressive characteristics and a poor prognosis, which is similar to triple-negative breast cancer in most respects. TNEOC should be considered in future investigations of informative classification of ovarian cancer.
Calcium inhibition halts developmental programmed cell death in the lace plant, Aponogeton madagascariensis?
Authors: Elliott Anna , Gunawardena Arunika H.L.A.N.
Published: March 2010

This study examined the effect of the calcium channel blocker ruthenium red (RR) on developmental programmed cell death (PCD) and perforation formation in leaves of the aquatic lace plant ( Aponogeton madagascariensis (Mirbel) H. Bruggen). Plant immersion experiments were conducted using various concentrations (0, 10, 20, 30, and 40 µmol·L–1) of RR applied to whole plants over a 3 to 4 week period. The ratio of number of leaf perforations per centimetre of leaf length along with leaf length were used to assess treatment effect. While the ratio of number of perforations per centimetre of leaf length was significantly reduced with RR treatment, leaf length was not, overall, significantly affected by RR. Therefore, it was concluded that RR was able to inhibit calcium movement and halt PCD, thus reducing perforation formation without having detrimental effects on leaf growth. The present research provides indirect evidence of the possible role of calcium in developmental PCD in vivo during leaf morphogenesis in the lace plant. Furthermore, it suggests the usefulness of the lace plant as a model system for pharmacological studies involving developmental PCD.
Introduced deer and the pollination and reproduction of an animal-pollinated herb
Authors: Vázquez Diego P. , Gresser Julie , Martin Jean-Louis
Published: March 2010

We evaluated the hypothesis that the modified population density of Aquilegia formosa Fisch. ex DC. (Ranunculaceae) resulting from the introduction of Sitka black-tailed deer ( Odocoileus hemionus sitkensis ) in the Haida Gwaii archipelago affects the pollination and reproductive performance of this herbaceous species. We compared the population density, pollination, and reproductive success of A. formosa among three small islands colonized by deer and three deer-free islands. Islands with deer had a substantially lower absolute density and a greater relative density of A. formosa than deer-free islands. The presence of deer was associated with higher pollen deposition, which probably resulted from the greater relative density of A. formosa on islands with deer. However, the presence of deer had no significant effect on individual reproductive success. The latter result is likely a consequence of the lack of pollen limitation in this species, as well as of the conflicting relationship between the absolute and relative densities of A. formosa and the presence of deer.
Riparian alder ecosystems as epiphytic lichen refugia in sub-boreal spruce forests of British Columbia
Authors: Doering Matthew , Coxson Darwyn
Published: March 2010

Alder-dominated riparian forests represent only a small proportion of the landscape in central-interior British Columbia. However, they possess a suite of attributes that may allow them to function as refugia for canopy macrolichens. These include their deciduous habitat, their location in moist nutrient receiving sites, and their distribution as narrow corridors that cross broad regional landscapes. We have examined their potential role as lichen refugia by assessing canopy macrolichen communities in 75 riparian alder forests across a 200 km longitudinal gradient in central-interior British Columbia. Study sites were stratified equally between three climate subzones of the Sub-Boreal Spruce biogeoclimatic zone. Forty-nine macrolichen taxa were observed, including the old-growth indicator cyanolichen species Lobaria scrobiculata (Scop.) DC., L. retigera (Bory) Trevisan, Nephroma isidiosum (Nyl.) Gyelnik, and Sticta limbata (Sm.) Ach. Canonical correspondence analysis identified mean annual temperature, mean annual precipitation, age of adjacent conifer forest, and abundance of large stems (dbh >10 cm) as significant explanatory variables. Regional precipitation gradients explained the exclusion of many lichen species from both the most westerly and most easterly riparian forests, with drier summer conditions and heavy winter snowpack, respectively, being major limiting factors. Lichens preferentially occupied large leaning stems, which may provide greater precipitation interception and continuity of substrate, when compared with smaller upright alder stems. We conclude that alder-dominated riparian forests represent a major refugium for old-growth dependent lichens in British Columbia’s sub-boreal spruce landscapes and as such may provide valuable dispersal corridors between remnant old-growth coniferous forest patches.
Factors affecting the production, growth, and survival of sprouting stems in the multi-stemmed understory shrub Lindera triloba
Authors: Matsushita Michinari , Tomaru Nobuhiro , Hoshino Daisuke , Nishimura Naoyuki , Yamamoto Shin-Ichi
Published: March 2010

We investigated the structure and dynamics of the multi-stemmed understory shrub Lindera triloba (Sieb. et Zucc.) Blume over 3 years in an old-growth coniferous forest, and quantitatively evaluated the factors affecting the ramet production, growth, and survival. Most genets sprouted continuously and exhibited multiple-stemmed structures with a few large and many small ramets. The skewed ramet-size distribution within genets resulted from the local crowding of neighboring trees, but not from the number of ramets within genets. This indicated that inter-plant competition is asymmetric (i.e., larger individuals outcompete one-sidedly smaller ones), but intra-plant competition (i.e., competition among ramets within genets) is symmetric (i.e., smaller ones also competitively affect larger ones). The local crowding of neighboring understory trees consistently negatively affected the ramet production, growth, and survival of L. triloba. Intra-genet crowding (i.e., crowding of ramets within genets) also negatively affected the ramet dynamics. On the other hand, the largest-ramet size within genets had positive relationships with the ramet dynamics, indicating that physiological integration within genets plays a role as supporting younger ramets. Based on our results, to fully understand genet persistence strategies in clonal shrub species, it is important to consider the effects of intra-genet crowding and modular integration, as well as plant-to-plant interaction.
Leaf damage has weak effects on growth and fecundity of common ragweed (Ambrosia artemisiifolia)
Authors: MacDonald A. Andrew M. , Kotanen Peter M.
Published: March 2010

The Enemy Release Hypothesis predicts that exotic plants gain an advantage over native competitors by losing their natural enemies while invading new regions. However, this assumes that those enemies reduced the performance of these invaders in their native ranges, and this may not be true if an invader is highly tolerant of herbivory. We used a field experiment to test the herbivore tolerance of a North American annual, common ragweed (Ambrosia artemisiifolia L.), which is known to have lost insect herbivores while invading Europe. We clipped leaves to simulate damage by folivores and removed meristems to simulate apical mortality caused by stem borers, and measured the consequences for growth and reproduction. Stem biomass was only reduced by defoliation far in excess of native-range natural damage, while seed production was unaffected by our treatments. Severely damaged plants maintained seed production by allocating relatively more aboveground biomass to reproduction. These results suggest that for the most part, damage by natural enemies may have little impact on this highly tolerant plant; consequently, enemy release may not have provided a significant advantage to this species in Europe. As well, biological control by insect folivores is unlikely to succeed unless it results in very high levels of damage.
Kennetcook thrust system: late Paleozoic transpression near the southern margin of the Maritimes Basin, Nova Scotia
Authors: Waldron John W.F. , Roselli Carlos G. , Utting John , Johnston Stanley K.
Published: March 2010

A major zone of deformation affects Early Carboniferous rocks in the southern part of the Maritimes Basin of Nova Scotia, close to the boundary between the Avalon and Meguma terranes of the Appalachians. Field relationships at Cheverie indicate thrusting of Tournaisian Horton Group clastics over Viséan Windsor Group carbonates, evaporites, and clastics, a relationship confirmed by the Cheverie #01 well. Mapped relationships to the south indicate that a system of thrusts, here termed the Kennetcook thrust system, climbs upsection to the southeast, becoming a décollement within Windsor Group evaporites. Industry seismic profiles clearly show deformed Windsor Group, and include fold and fault structures indicative of evaporite flow and solution collapse. Below the Windsor Group, half-grabens filled with Horton Group are clearly imaged; offsets at graben-related faults show that these structures were inverted during later shortening. Above the Windsor Group, less deformed rocks of the Pennsylvanian Scotch Village Formation (Cumberland Group) fill minibasins created by the withdrawal or solution of deformed Windsor evaporites. The timing of thrusting is constrained by these relationships and by crosscutting intrusions to a narrow interval around the Mississippian–Pennsylvanian boundary prior to ∼315 Ma. Deformation was probably related to dextral transpression along the former Avalon–Meguma boundary. Depending on how shortening was transmitted to the southeast, up to 1500 km2 of southern mainland Nova Scotia may be underlain by tectonically transported rocks.
The late Neoproterozoic Frog Lake hornblende gabbro pluton, Avalon Terrane of Nova Scotia: evidence for the origins of appinites
Authors: Pe-Piper Georgia , Piper David J.W. , Tsikouras Basilios
Published: March 2010

The late Neoproterozoic Frog Lake pluton, in the Avalon terrane of the Cobequid Highlands, Nova Scotia, consists predominantly of hornblende gabbro. It shows petrographic similarities to water-rich mafic intrusions known as appinites that are present in some collisional orogens. This study aims to further understanding of the origin of appinitic intrusions. In the field, the main hornblende gabbro was intruded between screens of metasedimentary country rock that is of upper greenschist metamorphic grade. The contacts appear to have been pathways for magma of gabbroic, tonalitic–granodioritic, and granitic composition that carried enclaves of gabbroic lithologies. Some of these magmas had a high volatile content, resulting in abundance of hydrous mineral phases, pegmatites, and diffuse felsic segregations. These varied rocks in the contact zones experienced progressive shear resulting in syn-magmatic deformation. Low-Ti hornblende gabbros have trace-element abundances similar to subduction-related low-K mafic rocks, including some enrichment in large-ion lithophile elements and marked relative depletion in Nb and Y. High-Ti hornblende gabbros and pyroxene–mica gabbro show more alkaline characteristics, with higher amounts of Nb, Y, P2O5, and high-field-strength elements. Tonalite and granite veins are geochemically similar to volcanic-arc granite. Comparison with appinites in the literature suggests that the Frog Lake pluton represents a deeper structural level than most appinites. The Frog Lake appinites were part of the feeder system to back-arc volcanic rocks of the Jeffers Group. Comparison with other appinites also leads to the conclusion that there is not a single type of “appinitic magma”: different appinitic plutons range in composition from low-K calc-alkaline to shoshonitic. The essential characteristic is a water-rich mafic magma. Appinites occur in settings undergoing crustal-scale strike-slip shear, where the faults allow rapid rise of mafic magma to shallow crustal levels.
Insights into the metamorphic evolution of the Belt–Purcell basin; evidence from Lu–Hf garnet geochronology
Authors: Zirakparvar N. A. , Vervoort J. D. , McClelland W. , Lewis R. S.
Published: March 2010

We have determined Lu–Hf garnet ages from spatially separated garnet bearing localities in northern Idaho. The Lu–Hf ages are diverse and reflect a progression of Mesoproterozoic metamorphic events. The oldest Lu–Hf garnet age determined in this study is 1463 ± 24 Ma for garnet within a kyanite schist exposed in the core-zone of the Boehls Butte metamorphic complex. A garnet schist from the Priest River complex yields a well-defined age of 1379 ± 8 Ma. A garnet–staurolite schist, a garnet–mica schist, and a gem-grade Idaho star garnet sample all from the general vicinity of Clarkia, Idaho, yield ages of 1064 ± 10, 1081 ± 20, and 1078 ± 17 Ma, respectively. A garnet amphibolite, also collected from the Boehls Butte metamorphic complex, yields an age of 1151 ± 41 Ma for garnet porphyroblasts and 137 ± 25 Ma for diffuse overgrowths. The Hf in all of the Proterozoic garnets is extraordinarily radiogenic with εHf values ranging from +1210 to +10546, which attest to both their high Lu/Hf ratios and their great antiquity. All of the samples analyzed in this study are from the rocks of the Mesoproterozoic Belt–Purcell Supergroup or its basement. These data provide evidence of polymetamorphism in northwestern Laurentia during the Mesoproterozoic.
When can we reliably estimate the productivity of fish stocks?
Authors: Conn Paul B. , Williams Erik H. , Shertzer Kyle W.
Published: March 2010

In modern fishery stock assessments, the productivity of exploited stocks is frequently summarized by a scale-invariant “steepness” parameter. This parameter, which describes the slope of the spawner–recruit curve, determines resilience of a stock to exploitation and is highly influential when estimating maximum sustainable yield. In this study, we examined conditions under which steepness can be estimated reliably. We applied a statistical catch-age model to data that were simulated over a broad range of stock characteristics and exploitation patterns and found that steepness is often estimated at its upper bound regardless of underlying productivity. The ability to estimate steepness reliably was most dependent on the true value of steepness, the exploitation history of the stock, natural mortality, duration of the time series, and quality of an index of abundance; this ability was relatively unaffected by levels of stochasticity in recruitment and sampling intensity of age compositions. We further explored the method of inverse prediction to improve estimates of steepness and conclude that this approach holds promise. We illustrate the utility of simulation and inverse prediction methods with two fish stocks located off the southeastern United States, greater amberjack ( Seriola dumerili ) and gag grouper ( Mycteroperca microlepsis ).
Relative value of limnological, geographic, and human use variables as predictors of the presence of Bythotrephes longimanus in Canadian Shield lakes
Authors: Weisz Erika J. , Yan Norman D.
Published: March 2010

The Eurasian aquatic invader Bythotrephes longimanus has spread rapidly throughout the Great Lakes watershed, particularly in Ontario, Canada, since its introduction in 1982. To date, the documentation of its spread has been largely anecdotal, not the result of planned surveys, so the actual distribution of the invader and the determinants of its distribution in Ontario remain uncertain. We surveyed 193 lakes in south-central Ontario to determine the importance of lake size, lake location, hydrological connection, and various physical, chemical, and human activity parameters in predicting the spread of Bythotrephes within the 1600-lake Muskoka watershed, North America’s most heavily invaded lake region. Invaded lakes were larger than uninvaded lakes and had less acidic, more nutrient-poor, clearer waters. Contingency analyses indicated that invaded lakes were more accessible to humans and had more heavily developed shorelines. Shoreline coverage by cottages was the strongest predictor of Bythotrephes presence when all physical, chemical, and human use variables were included in a logistic regression model. Our results support the growing consensus that humans are primarily responsible for the spread of Bythotrephes.
Empirical evaluation of predator-driven diel vertical migration in Lake Superior
Authors: Stockwell Jason D. , Hrabik Thomas R. , Jensen Olaf P. , Yule Daniel L. , Balge Matthew
Published: March 2010

Recent studies on Lake Superior suggest that diel vertical migration (DVM) of prey (generalized Coregonus spp.) may be influenced by the density of predatory siscowet ( Salvelinus namaycush ). We empirically evaluated this hypothesis using data from acoustic, midwater trawl, and bottom trawl sampling at eight Lake Superior sites during three seasons in 2005 and a subset of sites in 2006. We expected the larger-bodied cisco ( Coregonus artedi ) to exhibit a shallower DVM compared with the smaller-bodied kiyi ( Coregonus kiyi ). Although DVM of kiyi and cisco were consistent with expectations of DVM as a size-dependent, predator-mediated process, we found no relationship between siscowet density and the magnitude of DVM of either coregonid. Cisco appear to have a size refuge from siscowet predation. Kiyi and siscowet co-occur in demersal habitat > 150 m during the day, where visual predation is unlikely, suggesting predator avoidance is not a factor in the daytime distribution of kiyi. Seasonal patterns of kiyi DVM were consistent with reported DVM of their primary prey Mysis relicta . Our results suggest that consideration of nonvisual foraging, rather than light-based foraging theory (i.e., the antipredation window), is necessary to understand the processes driving DVM in deepwater systems.
Survival and life history characteristics among wild and hatchery coho salmon (Oncorhynchus kisutch) returns: how do unfed fry differ from smolt releases?
Authors: Thériault Véronique , Moyer Gregory R. , Banks Michael A.
Published: March 2010

Survival and life history characteristics were evaluated for a coho salmon ( Oncorhynchus kisutch ) integrated hatchery program using two stocking strategies. Fish were released as unfed fry or smolts and returned as adults, and then molecular analysis was employed to pedigree the entire population. We showed that mean adult survival of individuals released as unfed fry was less than that of individuals released as smolts (0.03% vs. 2.39%). The relative reproductive success (RRS) of the fry release strategy to wild spawning was significantly greater for one of two cohorts, whereas the smolt release strategy to wild RRS was significantly greater for both cohorts. Fish released as smolts were significantly smaller upon returning as adults than either those released as unfed fry or wild returns. Mean run timing was also significantly biased towards an earlier run time for hatchery-released fish when compared with the wild component. The incidence of jacking (males maturing at age 2) was greater among fish stocked as smolts than for fish stocked as fry. Differences in survival, RRS, and life history appeared to be the result of hatchery practices and indicated that a fry stocking strategy produced fish more similar to the wild component of the population than to that of fish released as smolts.
Forecasting the distribution of the invasive round goby (Neogobius melanostomus) in Wisconsin tributaries to Lake Michigan
Authors: Kornis Matthew S. , Vander Zanden M. Jake
Published: March 2010

The Laurentian Great Lakes host more than 180 non-native species, including several that have resulted in major economic and ecological effects. This list includes the round goby ( Neogobius melanostomus ), an aggressive, benthic Ponto-Caspian fish that has established large populations in coastal Great Lakes habitats. Here, we document the inland dispersal of round gobies into Wisconsin tributaries of Lake Michigan. Round gobies were detected in 26 of 73 streams (36%) and found >10 km upstream of Lake Michigan in nine watersheds. Round goby presence–absence was modeled using landscape-scale data from these invaded streams. We forecasted the future spread of round goby within Wisconsin’s Lake Michigan basin using our best model (80% accuracy), which included watershed area, stream gradient, and watershed slope as predictors. Round gobies were predicted to invade 1369 km of stream habitat up to the first stream barrier, and 8878 km of stream was identified as suitable looking beyond barriers at the broader Lake Michigan watershed (Wisconsin only). Our results depict the Great Lakes as a springboard for invasive species to disperse into inland ecosystems and, because round gobies are not usually reported in small streams in their native range, emphasize the utility of data from invaded regions when forecasting invasive species distributions.
Natal origin of Atlantic bluefin tuna (Thunnus thynnus) from Canadian waters based on otolith δ13C and δ18O
Authors: Schloesser Ryan W. , Neilson John D. , Secor David H. , Rooker Jay R.
Published: March 2010

Increased knowledge of stock mixing and migration of Atlantic bluefin tuna ( Thunnus thynnus ) is required to properly manage and conserve declining populations. Here, we predicted the nursery origin of giant bluefin tuna (n = 224) present in samples from Canadian waters using stable δ13C and δ18O isotopes in otoliths. The isotopic composition of milled otolith cores (corresponding to the first year of life) of giant bluefin tuna from three decades (1970s, 1980s, 2000s) and three regions within or adjacent to the Gulf of St. Lawrence was compared with otolith δ13C and δ18O of yearling bluefin tuna collected from eastern (Mediterranean Sea – eastern Atlantic, n = 136) and western (western Atlantic, n = 103) nurseries. Maximum likelihood estimates indicated that greater than 99% of bluefin tuna in our Canadian samples originated from the western nursery. No significant differences in estimates of origin for bluefin tuna were detected among decades or among regions, suggesting little to no mixing of eastern and western populations in the Canadian samples examined. These findings justify the use of catch rates from the Gulf of St. Lawrence area as an index of abundance for the oldest members of the western population.
Engineering of nanometer-sized cross-linked hydrogels for biomedical applications
Authors: Oh Jung Kwon
Published: March 2010

Microgels/nanogels (micro/nanogels) are promising drug-delivery systems (DDS) because of their unique properties, including tunable chemical and physical structures, good mechanical properties, high water content, and biocompatibility. They also feature sizes tunable to tens of nanometers, large surface areas, and interior networks. These properties demonstrate the great potential of micro/nanogels for drug delivery, tissue engineering, and bionanotechnology. This mini-review describes the current approaches for the preparation and engineering of effective micro/nanogels for drug-delivery applications. It emphasizes issues of degradability and bioconjugation, as well as loading/encapsulation and release of therapeutics from customer-designed micro/nanogels.
Synthesis of N-vinylcarbazole–N-vinylpyrrolidone amphiphilic block copolymers by xanthate-mediated controlled radical polymerization
Authors: Huang Chih-Feng , Yoon Jeong Ae , Matyjaszewski Krzysztof
Published: March 2010

Amphiphilic block copolymers poly(N-vinylcarbazole)-b-poly(N-vinylpyrrolidone) (PNVK-b-PNVP) were prepared by xanthate-mediated reversible addition-fragmentation chain transfer (RAFT) polymerization. Both the PNVK and PNVP macroinitiators and the resulting block copolymers had molecular weights close to theoretical values, predicted for efficient initiation, in the range of Mn = 30 000 to 90 000. The block copolymers dissolved in several organic solvents but, depending on their composition, in methanol formed either micelles or large aggregates, as confirmed by dynamic light scattering. The presence of globular aggregates was confirmed by tapping mode atomic force microscopy.
Conductivity percolation of carbon nanotubes (CNT) in polystyrene (PS) latex film
Authors: Uğur Ş. , Yargi Ö. , Pekcan Ö.
Published: March 2010

In this study, the effect of multiwalled carbon nanotubes (MWNT) on film formation behaviour and electrical conductivity properties of polystrene (PS) latex film was investigated by using the photon transmission technique and electrical conductivity measurements. Films were prepared by mixing PS latex with different amounts of MWNTs, varying in the range between 0 and 20 wt%. After drying, MWNT content films were separately annealed above the glass transition temperature (Tg) of PS, ranging from 100 to 270 °C, for 10 min. To monitor film formation behavior of PS–MWNT composites, transmitted light intensity, Itr, was measured after each annealing step. The surface conductivity of annealed films at 170 °C was measured and found to increase dramatically above a certain fraction of MWNT (4 wt%) following the percolation theory. This fraction was defined as the percolation threshold of conductivity, Rc. The conductivity scales with the mass fraction of MWNT as a power law with exponent 2.27, which is extremely close to the value of 2.0 predicted by percolation theory. In addition, the increase in Itr during annealing was explained by void closure and interdiffusion processes. Film formation stages were modeled and the corresponding activation energies were measured.
The role of molecular volume and the shape of the hole transport molecule in the morphology of model charge transport composites
Authors: Khan Ferdous , Khanna Shalini , Hor Ah-Mee , Sundararajan P. R.
Published: March 2010

We present a study of the morphology and molecular interactions in a model charge transport composite with 1,1-bis(di-4-tolylaminophenyl) cyclohexane (TAPC) as the hole transport molecule in bisphenol-A polycarbonate (BPAPC) and cyclohexyl polycarbonate, also known as bisphenol-Z polycarbonate (PCZ). Solution NMR shows that while there is aromatic interaction between the phenyl groups of the polycarbonate and TAPC, the broadening of the peaks corresponding to the latter indicates a decrease in the rotational motion. FTIR spectroscopy also exhibits frequency shifts of the aromatic C–H absorption peaks, which parallels the extent of the depression of the glass transition temperature (Tg) of the polycarbonate. These are compared with the previous results for N,N-diphenyl-N,N-bis(3-methylphenyl)-[1,1-biphenyl]-4,4-diamine (TPD) and tri-p-tolylamine (TTA), and the differences are rationalized on the basis of the molecular shape and van der Waals volume of the small molecules. It is proposed that when the polycarbonate is in a random coil conformation, spherical small molecules (e.g., TAPC and TTA) reduce the glass transition temperature much more than a rodlike small molecule (e.g., TPD). Annealing at a temperature just below the Tgof the polycarbonate was used as a means of simulating accelerated ageing. Upon annealing, phase separation and crystallization of TAPC occurs and leads to a recovery of the Tgof the polymer significantly. The Tgrecovery in this case is much more significant than in the case of TPD. The average crystal sizes are about ten times smaller than the crystals obtained in the case of TPD for the same temperature of annealing. To enhance the charge mobility, it might actually be advantageous to induce submicron crystals of the small molecule, while keeping the film transparent.
Genetic correlations between spiral grain and growth and quality traits in Picea abies
Authors: Hallingbäck Henrik R. , Jansson Gunnar , Hannrup Björn
Published: March 2010

In Norway spruce ( Picea abies (L.) Karst), spiral grain is a major cause of twist development in sawn timber; this problem could be addressed by breeding for reduced grain angles. This study presents estimates of genetic correlations between grain angle under bark and height and diameter growth; branch number, angle, and thickness; stem straightness; ramicorn occurrence; and pilodyn penetration using data from three progeny trials. The genetic relationship between grain angle development and radial growth was also investigated by measuring multiple annual rings (3–15) in stem sections from two clonal trials. Grain angles under the bark exhibited substantial heritability but near-zero genetic correlations with all the other traits studied. The genetic correlations between multiple ring grain angle and radial growth were also close to zero among all rings. However, radial growth exhibited positive genetic correlations with grain angles at specific distances from the pith and with radial grain angle trends, suggesting that the higher grain angles in juvenile wood extend further from the pith as a result of increased radial growth. Therefore, from a sawtimber perspective, the genetic relationship with radial growth may be unfavourable, despite the lack of genetic correlations between grain angle and radial growth at any particular annual ring.
Can structural and functional characteristics be used to identify riparian zone width in southern Appalachian headwater catchments?
Authors: Clinton Barton D. , Vose James M. , Knoepp Jennifer D. , Elliott Katherine J. , Reynolds Barbara C. , Zarnoch Stanley J.
Published: March 2010

We characterized structural and functional attributes along hillslope gradients in headwater catchments. We endeavored to identify parameters that described significant transitions along the hillslope. On each of four catchments, we installed eight 50 m transects perpendicular to the stream. Structural attributes included woody and herbaceous vegetation; woody debris and forest floor mass, nitrogen (N) and carbon (C); total soil C and N; litterfall amount and quality by species; and microclimatic conditions. Functional attributes included litter decomposition, soil microarthropods, soil CO2evolution, soil solution chemistry, and soil extractable N. Forest floor mass, N and C, and soil depth increased with distance from the stream and transitioned between 10 and 20 m. In contrast, litterfall N rate (kilograms of nitrogen per hectare per day), downed woody debris, soil A-horizon C and N, and soil solution NO3concentration all decreased with distance, and exhibited significant transitions. Certain overstory species were more abundant in the uplands than near the stream. Herbaceous diversity and richness were similar across the hillslope, but species distributions varied in response to hillslope moisture content. Taken together, these results suggest that at 10–20 m from the stream, transitions occur that separate riparian from upland conditions and may provide valuable insight into riparian zone definition.
Spatial variability of tree growth along a latitudinal transect in the Qilian Mountains, northeastern Tibetan Plateau
Authors: Liang Eryuan , Shao Xuemei , Eckstein Dieter , Liu Xiaohong
Published: March 2010

Little is known about the spatial variability in tree growth and its responses to climate on the Tibetan Plateau; however, such information is essential for improving predictions of forest ecosystem response to climatic change. A network of 16 ring width chronologies was developed along a latitudinal transect in the Qilian Mountains, northeastern Tibetan Plateau. A principal components analysis revealed that the residual chronologies had a positive loading on the first unrotated principal component (PC1). After rotation, PC1 yielded the highest loadings on the driest sites in the northwest and decreased to the south and to the east. PC2 was negatively correlated with altitude. Moisture availability was a dominant limiting factor for tree growth, and this dominance increased northwards and westwards along the precipitation gradient. Loadings of the first two rotated principal components separated the 16 forest sites into three major groups corresponding to the three regions affected by the East Asian Monsoon, Westerlies, and their interaction. Thus, spatial variability in tree growth is an excellent bioindicator of regional climate.
Assessment of beech scale resistance in full- and half-sibling American beech families
Authors: Koch Jennifer L. , Carey David W. , Mason Mary E. , Nelson C. Dana
Published: March 2010

A beech bark disease infested American beech tree ( Fagus grandifolia Ehrh.) and two uninfested trees were selected in a mature natural stand in Michigan, USA, and mated to form two full-sib families for evaluating the inheritance of resistance to beech scale ( Cryptococcus fagisuga Lind.), the insect element of beech bark disease. Four half-sib families from both infested and uninfested trees were also evaluated for resistance. Using an artificial infestation technique, adult and egg count data were collected over 2 years and analyzed with generalized linear mixed methods to account for nonnormal distributions of the response variables. A significant effect for family was found for each variable. Family least squares means were computed as a measure of resistance and repeatabilities were calculated to provide an upper limit estimate of broad-sense heritability. The two families that ranked highest for resistance were the full-sib family from two uninfested parents and the half-sib family from a stand where all diseased trees had been removed. Together, the results suggest that selection and breeding may be an effective means to improve populations for artificial regeneration, and silvicultural treatments may provide an effective management option for mitigating beech bark disease through managing the genetic composition of natural regeneration.
Regeneration dynamics after patch cutting and scarification in yellow birch – conifer stands
Authors: Prévost Marcel , Raymond Patricia , Lussier Jean-Martin
Published: March 2010

We present the 6 year effects of different cutting patterns (patch-selection cutting with 20, 30, and 40 m diameter gaps, 1 ha patch clear-cut, and uncut control) and spot scarification, on seedbed coverage and regeneration dynamics in yellow birch ( Betula alleghaniensis Britton) – conifer stands in eastern Quebec, Canada. After 3 years, yellow birch had established better in cutting patterns with gaps than in the patch clear-cut and in the control, while its density was 7 times higher in scarified than in nonscarified subplots. After 6 years, scarified openings and the borders of openings had 3–5  times more seedlings >30 cm in height than nonscarified openings and the understory between the gaps. The loss of advance growth in openings was the main result for conifer species, although recruitment of new balsam fir ( Abies balsamea (L.) Mill.) seedlings was accelerated by scarification. Despite the abundance of red spruce ( Picea rubens Sarg.) seed-trees on the site, our treatment combinations failed to promote its natural regeneration. Varying gap size did not change the total density of competing vegetation but modified the composition of this shrub layer. Our 6 year results suggest that maintaining conifer species, and the mixed composition of the stands, is uncertain over the long term.
Fine root decomposition in two subalpine forests during the freeze–thaw season
Authors: Wu Fuzhong , Yang Wanqin , Zhang Jian , Deng Renju
Published: March 2010

Little is known about fine root decomposition during the freeze–thaw season. To characterize fine root decomposition during this time (from October 2006 to April 2007), a field experiment was conducted to examine the decomposition of fine roots (diameters of 0–1 and 1–2 mm) of Minjiang fir ( Abies faxoniana Rehd. & E.H. Wilson) and Asian white birch ( Betula platyphylla Sukaczev) using buried litterbags in their respective habitats in western Sichuan, China. Over one freeze–thaw season, 14%–20% of mass was lost and 12%–31% of C, 6%–36% of N, 15%–25% of P, and 37%–43% of K were released. These losses accounted for about 40%–55% of mass lost and 23%–54% of C, 23%–89% of N, 25%–42% of P, and 48%–58% of K released within the first year of fine root decomposition. The amount of mass loss and bioelements release during the freeze–thaw season correlated closely with initial substrate quality and bioelement traits. Compared with birch fine root, fir fine root decomposition could be influenced more by decomposition processes during the freeze–thaw season. Results suggest that fine root decomposition during the freeze–thaw season can strongly contribute to ecosystem C and nutrient cycling.
Size-symmetric versus size-asymmetric competition and growth partitioning among trees in forest stands along an ecological gradient in central Europe
Authors: Pretzsch Hans , Biber Peter
Published: March 2010

Current individual tree growth models rarely consider the mode of tree competition, which can be size-asymmetric when growth is limited by light or size-symmetric when belowground resources are scarce. Even with the same competition index, growth reactions may vary considerably due to a prevailing resource limitation, as the dominant trees in a stand benefit disproportionately more on light-limited sites. To scrutinize and model the relationship between mode of competition and site conditions, 34 long-term experiments with 120 plots dating back to 1871 were used. The data cover the dominating tree species in central Europe along a broad range of ecological conditions. For Norway spruce ( Picea abies (L.) Karst.), Scots pine ( Pinus sylvestris L.), and sessile oak ( Quercus petrea (Matt.) Liebl.), stronger light competition can be shown on fertile sites compared with sites with poorer conditions. Based on these findings, we constructed an enhanced version of a classic potential modifier growth model. Simulations for archetypical stands yield a transition from size-asymmetric to size-symmetric competition along the gradient from fertile to poor sites that is not covered by traditional models. It was concluded that by integrating the interaction between competition and site quality, individual tree models become more site sensitive, a prerequisite for their application under fluctuating environmental conditions.
Influence of moisture and freeze–thaw on leaf microbial community dynamics
Authors: Corrigan C. , Oelbermann M.
Published: March 2010

In forest ecosystems, litterfall that collects in trapping devices, to quantify organic matter and nutrient inputs, is exposed to periods of wetting, drying, freezing, and thawing. These fluctuating environmental conditions may influence the microbial community structure inhabiting the leaves and may result in the loss of mobile nutrients, leading to an underestimation of actual organic matter and nutrient inputs. The objectives of this study were to evaluate the influence of (i) different quantities of moisture (LOW = 30 mm, MED = 60 mm, HI = 100 mm) and (ii) freeze–thaw (FT) on leaf (sugar maple ( Acer saccharum Marsh.), American basswood ( Tilia americana L.), and American beech ( Fagus grandifolia Ehrh.)) microbial activity and community structure. There was a significantly greater (p < 0.05) CO2production rate in LOW and FT treatments for sugar maple and beech, and in HI and FT treatments for basswood. A similar trend occurred for leaf nitrogen concentration but not for carbon (C). Utilization of C substrates was up to 10% greater in the FT treatments. Principal components analysis on the activity of C source utilization showed a distinct clustering between leaf species and between treatments following a pattern similar to that of microbial respiration. Results from this study suggested that the collection of litter should take place more frequently during seasons when frost is imminent.
A DYNAMIC MODEL FOR THE HETEROGENEOUS TRAFFIC FLOW CONSISTING OF CAR, BICYCLE AND PEDESTRIAN
Authors: TANG TIE-QIAO , HUANG HAI-JUN , SHANG HUA-YAN
Published: March 2010

Based on the properties of the heterogeneous traffic flow consisting of car, bicycle and pedestrian, we in this paper present three individual-following models with the consideration of the friction effects, where the individual can here be referred to as car, bicycle or pedestrian in a unified manner. Using the relationship between the micro and macro variables, we obtain a dynamic model for heterogeneous traffic flow with the consideration of the friction effects. The analytical and numerical results show that the bicycle friction effect will reduce the car flow and speed and that the pedestrian friction effect will reduce the bicycle flow and speed, but the reductions are related to the bicycle and pedestrian density.
AUTOMATED TRAFFIC ROUTING BASED ON THE RIP AND EIGRP ALGORITHMS USING CELLULAR AUTOMATA
Authors: FOWDUR S. C. , RUGHOOPUTH S. D. D. V.
Published: March 2010

The Routing Information Protocol (RIP) and Enhanced Interior Gateway Routing Protocol (EIGRP) algorithms are widely used in the field of telecommunications for transmission of data over computer networks. Traffic Cellular Automata (TCA) is a technique that has proved to be very efficient in simulating large-scale road traffic networks. In this paper a multicell TCA model that includes anticipation and probability randomization has been hybridized with the RIP and EIGRP algorithms. Simulation was performed on a small network and the performance of these two algorithms compared and analyzed. The results show that the EIGRP algorithm, through an adaptive routing of vehicles, achieves reduced travel times, more space-headway and lower traffic densities.
LATTICE BOLTZMANN SIMULATION OF ELECTROOSMOTIC MICROMIXING BY HETEROGENEOUS SURFACE CHARGE
Authors: TANG G. H. , WANG F. F. , TAO W. Q.
Published: March 2010

Microelectroosmotic flow is usually restricted to low Reynolds number regime, and mixing in these microfluidic systems becomes problematic due to the negligible inertial effects. To gain an improved understanding of mixing enhancement in microchannels patterned with heterogeneous surface charge, the lattice Boltzmann method has been employed to obtain the electric potential distribution in the electrolyte, the flow field, and the species concentration distribution, respectively. The simulation results show that heterogeneous surfaces can significantly disturb the streamlines leading to apparently substantial improvements in mixing. However, the introduction of such a feature can reduce the mass flow rate in the channel. The reduction in flow rate effectively prolongs the available mixing time when the flow passes through the channel and the observed mixing enhancement by heterogeneous surfaces partly results from longer mixing time.
PSEUDO RANDOM NUMBER GENERATOR BASED ON SYNCHRONIZED CHAOTIC MAPS
Authors: AKHSHANI AFSHIN , BEHNIA SOHRAB , AKHAVAN AMIR , LIM SIEW-CHOO , HASSAN ZAINURIAH
Published: March 2010

In this paper, a hierarchy of coupled maps in synchronized state is introduced. Then some discussions about the individual properties of these chaotic maps are presented, from a dynamical systems viewpoint. Also, one of these chaotic map is used as a Nonlinear Pseudo Random Generator (NPRNG). This paper addresses the chaotic features of this map which are useful for generating nonlinear pseudo random numbers. Results of the analysis and extensive tests such as the NIST, DIEHARD and ENT test suites indicate that the NPRNG exhibits good statistical randomness properties.
TIME VARIABLE COSMOLOGICAL CONSTANT FROM RENORMALIZATION GROUP EQUATIONS
Authors: XU LIXIN
Published: March 2010

In this paper, a time variable cosmological constant (CC) from renormalization group equations (RGEs) is explored, where the renormalization scales μ2 = Ḣ + 2H2 and μ2 = - Ḣ are taken respectively. The cosmological parameters, such as dimensionless energy density, deceleration parameter and effective equation of state of CC etc., are derived. Also, the cosmic observational constraints are implemented to test the model's consistency. The results show that it is compatible with cosmic data. So, it would be a viable dark energy model.
PARALLEL TRANSPORT IN MOMENTUM de SITTER SPACE AND DSR
Authors: MAGPANTAY JOSE A.
Published: March 2010

It is shown that the momentum coproduct rules in the bi-cross-product basis of κ Poincaré do not arise from parallel transport in de Sitter momentum space. An alternative coproduct rule from parallel transport is derived. It is then argued that the momentum coproduct rules in other DSR theories also do not follow from the parallel transport rule.
HIGHER ORDER FIRST INTEGRALS OF MOTION IN A GAUGE COVARIANT HAMILTONIAN FRAMEWORK
Authors: VISINESCU MIHAI
Published: March 2010

The higher order symmetries are investigated in a covariant Hamiltonian formulation. The covariant phase-space approach is extended to include the presence of external gauge fields and scalar potentials. The special role of the Killing–Yano tensors is pointed out. Some nontrivial examples involving Runge–Lenz type conserved quantities are explicitly worked out.