bluuebunny/crossref_metadata_2025 huggingface dataset:
Interactions between Lipids and Human Anti-HIV Antibody 4E10 Can Be Reduced without Ablating Neutralizing Activity
Authors: Xu Hengyu , Song Likai , Kim Mikyung , Holmes Margaret A. , Kraft Zane , Sellhorn George , Reinherz Ellis L. , Stamatatos Leonidas , Strong Roland K.
Published: November 2009

Human 4E10 is one of the broadest-specificity, HIV-1-neutralizing monoclonal antibodies known, recognizing a membrane-proximal linear epitope on gp41. The lipid cross-reactivity of 4E10 has been alternately suggested either to contribute to the apparent rarity of 4E10-like antibody responses in HIV infections, through elimination by B-cell tolerance mechanisms to self-antigens, or to contribute to neutralization potency by virus-specific membrane binding outside of the membrane-proximal external region (MPER). To investigate how 4E10 interacts with membrane and protein components, and whether such interactions contribute to neutralization mechanisms, we introduced two mutations into 4E10 Fv constructs, Trp to Ala at position 100 in the heavy chain [W(H100)A] and Gly to Glu at position 50 in the light chain [G(L50)E], selected to disrupt potential lipid interactions via different mechanisms. Wild-type and mutant Fvs all bound with the same affinity to peptides and monomeric and trimeric gp140s, but the affinities for gp140s were uniformly 10-fold weaker than to peptides. 4E10 Fv binding responses to liposomes in the presence or absence of MPER peptides were weak in absolute terms, consistent with prior observations, and both mutations attenuated interactions even further, as predicted. The W(H100)A mutation reduced neutralization efficiency against four HIV-1 isolates, but the G(L50)E mutation increased potency across the same panel. Electron paramagnetic resonance experiments showed that the W(H100)A mutation, but not the G(L50)E mutation, reduced the ability of 4E10 to extract MPER peptides from membranes. These results show that 4E10 nonspecific membrane binding is separable from neutralization, which is achieved through specific peptide/lipid orientation changes.
Role of Internal Phosphorus Loading in Two Shallow, Productive Lakes in Alberta, Canada
Authors: Riley E. T. , Prepas E. E.
Published: November 2009

The contribution of internal loading from the sediments to the total phosphorus (TP) budget and to the [TP] in the surface water was investigated from May to November in Nakamun and Halfmoon lakes, Alberta. During the summer, Nakamun Lake was intermittently stratified and Halfmoon Lake was weakly, thermally stratified. During the stratified periods, water overlying the sediments was anoxic, TP levels increased in the deep water, and sediments were the main source of TP, contributing 1468 and 147 kg of TP to Nakamun and Halfmoon lakes, respectively. During these same periods, internal loading to Nakamun and Halfmoon lakes (12.7 and 15.6 mg∙m−2∙d−1, respectively) were slightly higher than the rates predicted from laboratory experiments on sediment cores (9.7 and 7.2 mg∙m−2∙d−1, respectively). Quantitative estimates of vertical water exchange in Nakamun Lake and in-lake TP budgets for both lakes indicated that phosphorus released from the sediments was transported to the surface water during mixing. After eight of the nine mixing events that immediatley followed stratified periods, [TP] increased 3–43% and 31–52% in the surf ace water of Nakamun and Halfmoon lakes, respectively.
Brook Trout (Salvelinus fontinalis) Population Structure in Acidified Lac Tantaré, Quebec
Authors: Frenette Jean-Jacques , Dodson Julian J.
Published: November 2009

To present evidence of acid-induced stress, we studied the population structure and distribution of brook trout (Salvelinus fontinalis) in acidified Lac Tantaré, Quebec. Trout greater than 21 cm (FL) represented only 16.2 and 10% of the population sampled in 1979 and 1980, respectively. Survival rates of trout from 1979 to 1980 indicated higher survival among individuals > 25 cm, mortality occurring primarily among fish of 13–25 cm. The marked decline in numbers of fish occurring at 21 cm coincided with the size at which 50% of the female trout population reached sexual maturity, suggesting that postspawning mortality contributes to the high mortality observed among these fish. Comparisons of population and individual growth rates revealed that smaller fish of age-classes 1 to 5 suffer higher mortality than do the larger individuals of these age-classes, implicating mortality agents other than those related to spawning. We provide evidence to support the hypothesis that the most probable cause of mortality is size-related differential exposure to toxic stress whereby small brook trout (< 25 cm) are found in lake areas (brooks) exhibiting the most potentially toxic combination of pH and aluminum, thus enhancing the exposure of the most susceptible part of the population to toxic stress. Large brook trout [Formula: see text] are found in the "safest" lake areas (springs), thus diminishing the exposure of the least susceptible part of the population to toxic stress and enhancing survival. Female trout exhibit delayed sexual maturity relative to other Quebec populations, attaining 50% maturity at age 3 and a length of 21–24 cm such that the major part of the population's reproductive effort is provided by those fish representing only 15% of the population in 1979 and 1980. During the October spawning season, 20% of potential spawners exhibited retarded oogenesis. These reductions in reproductive effort and changes in spawning site selection provide evidence in support of the hypothesis that recruitment failure may be occurring in the Tantaré brook trout population.
Climatic and Oceanic Variations Affecting Yield of Icelandic Stocks of Atlantic Salmon (Salmo salar)
Authors: Scarnecchia Dennis L.
Published: November 2009

Regression analysis was used to investigate the effects of variations in climate, weather, and ocean conditions on yields of Atlantic salmon (Salmo salar) to anglers from 15 Icelandic rivers. Catches of grilse from the northern and northeastern group of rivers fluctuated together, as did catches from the southwestern and western group of rivers, but seldom did catches from the two groups of rivers fluctuate together. The dividing point for grouping rivers with similarly fluctuating catches was the northwest peninsula, which separated warm Atlantic water from colder north Icelandic waters of the Iceland Sea. Changes in atmospheric circulation (mid-1950's to mid-1960's) resulted in marked changes in hydrography off north Iceland from 1965 to 1970, which coincided with declines in primary production and standing crops of zooplankton, in reduced abundance and altered distribution of pelagic forage fishes, and in declines in salmon yields from north coast rivers. Few grilse were also caught from most rivers in 1980 after low sea and air temperatures in spring of 1979. Highly significant relationships were found between mean June–July sea temperatures at Hraun on the north coast and yield of grilse the following year from the northern rivers Vatnsdalsá, Vídidalsá, Hrútafjardará, and Midfjardará and its three tributaries. Sea temperatures in April–May and May–June were also closely correlated (P < 0.01 and P < 0.05) with grilse catches from these rivers. Correlations were similar but less close for two-sea-winter salmon. Fewer statistically significant relations were found between sea temperatures and yields for south coast rivers; sea temperatures were higher there and varied less between years. Inasmuch as low sea temperatures and low river temperatures often occur in the same years, salmon yields may be regulated by several adverse climatic and hydrographic factors acting in combination, resulting in delayed smoltification and reduced growth and survival at sea.
In Situ Measures of Dissolved Organic Carbon Flux in a Rural Stream
Authors: Kuserk Frank T. , Kaplan Louis A. , Bott Thomas L.
Published: November 2009

Dissolved organic carbon (DOC) dynamics were measured in a second-order stream located in a pasture in southeastern Pennsylvania. In situ measurements made at six stations in early summer showed a diel patern of net DOC release from the streambed communities with predawn minima and afternoon maxima. When an 18-m section of the stream was covered with black plastic for 1 mo to exclude algal growth and measures were repeated in late summer, a net removal of DOC occurred in the covered section, while in an adjacent uncovered section DOC was released. When a bovine manure extract was introduced into the covered section, the DOC removal rate increased by more than an order of magnitude. Jewel-weed (Impatiens capensis L.) extract also elicited an elevated rate of DOC removal. When these extracts were added individually to microcosms, removal rates in the dark were 57 and 65% of the in situ uptake estimates for the manure extract and leachate, respectively. Abiotic controls showed that nearly all of the DOC removal was biotic uptake. DOC flux measurements in a third-order section of White Clay Creek, located on an adjacent watershed, also revealed a net DOC release from the uncovered streambed. Introduction of a bovine manure extract elicited a DOC removal rate an order of magnitude less than in the pasture stream. A companion microcosm experiment yielded an uptake rate that was 178% of the in situ estimate.
Changes in Nutrient Levels of Lake Water Stored at 4 °C
Authors: El-Shaarawi A. H. , Neilson M. A.
Published: November 2009

Water samples were collected on Lake Ontario during April and November, filtered (0.45 μm), and immediately analyzed onboard ship for the nutrients soluble reactive phosphorus, nitrate-plus-nitrite, and ammonia. Replicates were stored in glass bottles at 4 °C and reanalyzed within 8 d. Statistical analysis showed that soluble reactive phosphorus decreased by 11 and 13% and nitrate-plus-nitrite by 7 and 6%, whereas ammonia increased by 75% on one cruise and decreased by 37% on the other.
Hydroacoustic Signal Classification of Fish Schools by Species
Authors: Rose G. A. , Leggett W. C.
Published: November 2009

Features extracted from hydroacoustic backscatter from fish schools enabled classification by species. Target species were cod (Gadus morhua), capelin (Mallotus villosus), and mackerel (Scomber scombrus), observed in the northern Gulf of St. Lawrence during 1985–86. Two features of internal school density (20 log R amplification) were the best discriminators. These were mean standardized peak to trough distance (SPT) and mean distance between voltage peaks (PP). Quadratic discriminant functions based on the variables SPT, PP, an inverse coefficient of variation, school depth, and off-bottom distance correctly classified 93% of schools (1986). These functions also correctly classified 93% of cod and capelin schools acoustically sampled independently during 1985. The target strength of individual fish was a less successful discriminator of species. For cod and capelin of known length, average target strength (TS) was a linear function of length: TS (decibels) = −65 + 20 log10 length (centimetres). Mackerel had target strengths that were 8–12 dB less than those of cod of equivalent length. Quadratic discriminant functions based on target strength, school depth, and off-bottom distance correctly classified 77% of schools by species. Our methods are generalized to any schooling species or environment.
Production by the Amphipod Pontoporeia hoyi in South Bay, Lake Huron
Authors: Johnson M. G.
Published: November 2009

Pontoporeia hoyi was the dominant profundal benthic macroinvertebrate comprising 70–90% of animals collected and averaging close to 2100 m−2 in the main profundal basin of South Bay, Lake Huron. Almost all production occurred in the profundal zone (1.15 g∙m−2∙yr−1) compared with the sublittoral zone (0.03 g∙m−2∙yr−1), attributable to a preference by older P. hoyi for cooler temperature. Production/biomass (P/B) averaged 1.4∙yr−1 in the profundal zone at mean annual temperature of 4.7 °C and 3.1∙yr−1 at 7.5 °C in the sublittoral zone. Instantaneous growth rates were the same as in the Bay of Quinte and adjacent Lake Ontario where production was six times that in South Bay. A similar difference in phytoplankton production occurred between the areas. Differences in biomass accounted for variation in P. hoyi production in the two areas. The South Bay data provide further evidence that benthic macroinvertebrate biomass reflects production consistent with values of P/B determined by temperature.
Hydrologic and Riparian Influences on the Import and Storage of Coarse Particulate Organic Matter in a Prairie Stream
Authors: Gurtz Martin E. , Marzolf G. Richard , Killingbeck Keith T. , Smith David L. , McArthur J. Vaun
Published: November 2009

The hydrologic regime and zonation of riparian vegetation influenced the quantity and quality of coarse particulate organic matter (CPOM; >1 mm) stored in the channel and upper bank of a prairie stream. In a 5.4-km intermittent reach of the South Branch of Kings Creek on Konza Prairie, Kansas, total annual import was lowest in headwater reaches and increased downstream. Total storage of benthic CPOM in the dry channel and on the bank before the flow period was highest in the fourth- and fifth-order gallery forest zone (999 g ash-free dry mass∙m−2) and less in upstream reaches (320–341 g∙m−2). These longitudinal patterns of CPOM annual import and storage (before the flow period) were opposite those predicted by the river continuum concept for streams draining forested regions. Following flow, headwater channels had more CPOM (291 g∙m−2) than downstream reaches. On the bank, storage was always highest in downstream reaches. Composition of CPOM both in the channel and on the bank varied with changes in riparian vegetation; grass tissues dominated in headwater channels, while wood and leaves of trees and shrubs were more abundant downstream. During the flow period, storage of CPOM increased only in headwater channels, where retention was high despite the lack of woody debris. In this intermittent prairie stream, benthic CPOM may not contribute consistently to the terrestrial/aquatic linkages that are suggested in the river continuum concept because of (1) a paucity of large CPOM sources (e.g. trees, shrubs) in the upper reaches and (2) a hydrologic regime that reduces the amount, as well as the predictability, of stored CPOM. The biota of prairie streams must have opportunistic food gathering and reproductive strategies to take advantage of variable food resources in a flow environment that is itself very unpredictable.
Effects of Low-Level Gas Supersaturation on Lake Trout (Salvelinus namaycush)
Authors: Krise William F. , Meade James W.
Published: November 2009

Eggs, eleutheroembryos, and alevins of lake trout (Salvelinus namaycush) were reared in 1 of 10 levels of total gas pressure (TCP) ranging from 13 to 81 mm Hg (ΔP) above ambient barometric pressure. Rearing water was soft (30–40 mg CaCO3/L, pH 6.8), temperature was 9.3 °C, and the exogenous feeding portion of the test lasted 98 d. The supersaturation levels tested had no effect on the total survival of eggs, eleutheroembryos, or alevins, and condition factor and mean weight of fish in each treatment were statistically unchanged at the end of the study. Most of the fish that died during the feeding trial were small, had a below-average condition factor, and showed petechial hemorrhaging in the abdominal region. Length frequency distributions differed significantly among treatment groups after 56 d of feeding and remained different through 98 d. There was no difference in weight gain, condition factor, food conversion, and mortality, indicating that these measures are not useful for predicting or monitoring effects within the range of gas levels tested. The estimated incipient lowest level of effect of gas supersaturation remains unclear. A conservative recommendation of maximum supersaturation levels for small lake trout would be in the lower treatment levels used in this study.
A Tag–Release/Recovery Method for Predicting the Effect of Changing the Catch of One Component of a Fishery Upon the Remaining Components
Authors: Majkowski Jacek , Hearn William S. , Sandland Ronald L.
Published: November 2009

We describe (and illustrate, using data on southern bluefin tuna, Thunnus maccoyii) a tag–release/recovery experiment designed to predict the effect of changing the catch of one component of a fishery upon the remaining components for which fishing patterns and intensities are fixed. Formulae are developed for estimating the predicted changes and their standard errors. We also demonstrate how to determine the number of fish that should be tagged to achieve a desired accuracy of results from such an experiment. The proposed approach requires neither comprehensive knowledge of mechanisms governing the fish population and fishery being considered nor extensive historical catch and fishing effort data, but it will reflect all aspects of the dynamics of the system if the tag–release/recovery experiment is properly implemented. Consequently, it can be applied to many complex fisheries systems for which this knowledge is lacking. However, the proposed approach does not enable predictions to be made when the change in the catch significantly alters the number of recruits to the fishable stock, changes the fish behaviour, or changes the rates of natural mortality, migration, or growth.
Secondary Production of Tiger Salamanders (Ambystoma tigrinum) in Three North Dakota Prairie Lakes
Authors: Deutschman Mark R. , Peterka John J.
Published: November 2009

In three prairie lakes studied in 1981–82, larval tiger salamander (Ambystoma tigrinum) densities reached highs of 5000∙ha−1, maximum biomass (wet weight) was 180 kg∙ha−1, and maximum annual production was 565 kg∙ha−1. Within a given lake, overwinter survival of larvae varied markedly from year to year. Overwinter survival of larvae was excellent in Lake II; in spring 1981, densities were 800–1000∙ha−1. In 1982, no larvae overwintered in Lake II, and none overwintered in Lake I in either 1981 or 1982. In May 1981, larvae were large (mean weight of 150 g) and their biomass of 150 kg∙ha−1 was nearly as large as the maximum biomass of 160 kg∙ha−1 in late July of larvae from the year's cohort. This was in contrast with 1982 in Lake II and with both 1981 and 1982 in Lake I when there was an extremely low biomass in the spring, composed of many small larvae. The large larvae that overwintered in Lake II in 1981 did not prey on young-of-the-year larvae; their high densities may have actually reduced invertebrate predation on salamander larvae; in July, larval salamander densities of 5000∙ha−1 were the highest measured.
Effect of Black Fly Ingestion and Assimilation on Seston Transport in a Quebec Lake Outlet
Authors: Morin Antoine , Back Christian , Chalifour Alain , Boisvert Jacques , Peters Robert H.
Published: November 2009

Ingestion and assimilation rates of simullid (Diptera) larvae feeding on natural seston were estimated in an artificial stream and used to predict the impact of simuliids on seston transport in a 40-m section of the outlet stream of Petit Lac Fraser in southern Quebec. This prediction was then compared with changes in the seston flux above and below the population. Finally, we selectively killed simuliids with a larvicide (Bacillus thuringiensis serovar. israelensis) to observe changes in seston transport after removal of simuliids. The stream population of simuliid larvae ingested between 32 and 55% of the seston flux and assimilated between 17 and 25% of the dry mass of ingested seston. The change in assimilation of seston in the stream section before and after the larvicide treatment was similar to that predicted from assimilation rate of larvae and standing stock. Larvae ingested 0.8–1.4% of the seston per linear meter of stream, about 10–1000 times more than what has been reported for other populations of stream filter-feeders. The high values observed can be explained by high specific ingestion rates, high standing stock, and low discharge. Our results suggest that simuliid populations can be food limited and may help to explain the downstream decrease in abundance and growth rates of filter-feeders in lake outlets.
Photosynthetic Carbon Metabolism by Phytoplankton in a Nitrogen-Limited Reservoir
Authors: Groeger Alan W. , Kimmel Bruce L.
Published: November 2009

Phytoplankton in the downlake epilimnion of Normandy Lake, a central Tennessee reservoir, responded to summer N deficiency by increasing relative rates of lipid synthesis from 10–15% up to 20–35% of the total photosynthetic C fixation. Phytoplankton in more N-sufficient areas of the reservoir (downlake in a metalimnetic chlorophyll peak and uplake near the river inflow) maintained lower rates of lipid synthesis, generally [Formula: see text] of the total fixed C, throughout the summer. NH4 enrichment of N-deficient phytoplankton inhibited photosynthesis and significantly depressed the high lipid synthesis rates; however, NH4 enrichment had no effect on the phytosynthesis or lipid synthesis of N-sufficient phytoplankton. Our results document, for the first time, the occurrence of high lipid synthesis rates associated with the N limitation of natural phytoplankton assemblages. This relationship has previously been observed only in laboratory algal culture studies.
Measuring Abundance of Emerging Chironomidae (Diptera): Experiments on Trap Size and Design, Set Duration, and Transparency
Authors: Welch Harold E. , Jorgenson John K. , Curtis Martin F.
Published: November 2009

Experiments at Saqvaqjuac, N.W.T. (63°39′N) showed that submerged funnel traps (0.283 m2) had equal catch rates at 10–12 °C, independent of emptying interval between 1 and 6 d. Inverted funnels in the trap jars reduced the loss of active pupae, and probably sinking dead insects. Catch rates were independent of trap size (0.071–0.283 m2) at emergence densities [Formula: see text]. Preserving-type traps which retained the catch had the same daily catch rate as regular traps when left in place up to 18 d, but none of the preservatives tried was satisfactory and decay was a problem. Catch rates for clear and opaque traps were similar.
Vertical Distribution of Sediment and Organic Debris in Coho Salmon (Oncorhynchus kisutch) Redds in Three Small Oregon Streams
Authors: Ringler Neil H. , Hall James D.
Published: November 2009

Vertical distribution of sediment (particle diameter <3.33 mm) and organic debris was studied in coho salmon (Oncorhynchus kisutch) redds in three Oregon coastal streams subjected to different degrees of logging. Gravel composition in frozen cores varied significantly among redds in both logged streams. Sediment content in redds appeared to decrease with depth in the logged streams, but differences in gravel composition among streams obscured differences among depths. Sediment layers of variable thickness were visible in several core samples. In one logged stream, redds contained an average of 25% less sediment than redds used 1 yr earlier. Organic content of the gravel represented <2.8% of the core samples by weight and was directly related to the quantity of sediment in the streambed. The pattern of vertical distribution of organic debris in the clearcut stream (most abundant near the surface) differed significantly from that in the other two streams. Patterns of distribution and variability in gravel composition were consistent with post-logging changes in gravel permeability and survival to emergence of coho salmon.
Particles in "Particle-free" Seawater: Growth of Ultraphytoplankton and Implications for Dilution Experiments
Authors: Li William K. W.
Published: November 2009

Ultraphytoplankton cells were detected by flow cytometry in seawater that passed through filters of the finest pore size commonly used in aquatic research (0.22-μm Millipore®, 0.45-μm Millipore®, 0.2-μm Nuclepore®, Whatman®GF/F). Although the relative number of cells in freshly prepared filtrate was very small (generally less than 1% of the intact assemblage), the number of such cells increased rapidly during incubation. The implication of this apparent growth was investigated in dilution experiments where diluent was mixed with unfiltered seawater in varying proportions. Plots of apparent rate of change versus dilution factor were generally hyperbolic, with high rates at high dilutions. Simple calculations indicated that fluorometric measurements of bulk chlorophyll a would not have been able to detect these changes.
Retention and Resuspension of Phosphorus, Nitrogen, and Iron in a Central Ontario Lake
Authors: Dillon P. J. , Evans R. D. , Molot Lewis A.
Published: November 2009

Sediment traps were used to estimate the downward flux of total phosphorus, total Kjeldahl nitrogen, and iron in a small Precambrian shield lake for 4 yr. The flux as determined by the sediment trap method was much higher than the retention of the same elements as measured by mass balance methods (input–outflow). Total phosphorus (TP) sedimentation was about 17 times higher than retention while N was about three times higher and Fe was about 31 times higher. Very high N/P ratios in epilimnetic waters (36/1 by weight) and low N/P ratios in trap material (8/1) and surficial sediments (mean 8/1, range 4–11/1), in conjunction with high sedimentation to retention ratios, strongly suggest that resuspended sediment is a major component of trap material. Fe/TP ratios suggest that surficial sediment from shallow waters (< 13 m) was the largest contributor to resuspended sediment. Large amounts of biologically available phosphorus originating with resuspended sediment may enter upper waters. The difference between N/P ratios in surficial sediments (4–11/1) and nutrients retained from mass balance calculations (50/1) is attributed to denitrification.
Temperature-Dependent Growth of Juvenile Red King Crab (Paralithodes camtschatica) and its Effects on Size-at-Age and Subsequent Recruitment in the Eastern Bering Sea
Authors: Stevens Bradley G.
Published: November 2009

A temperature-based growth relationship was derived for juvenile red king crab (Paralithodes camtschatica) from published data. Growth of annual cohorts of crab was simulated at various locations in Bristol Bay, AK, using long-term water temperature observations, and the resulting mean sizes were compared with those observed by the annual National Marine Fisheries Service eastern Bering Sea crab survey. Results indicate that mean age-at-recruitment is 3–5 yr greater than previously estimated, and has decreased from 9.5 to 7.5 yr over the past decade as a result of increasing sea temperature. Single year-classes require 3–5 yr for complete recruitment to the 'mature' size interval, and recruitment in any year may consist of crabs from four to five year-classes. The high landings and subsequent crash of the Bering Sea red king crab population during the late 1970's probably originated from one or more adjacent strong year-classes in the late 1960's which recruited over a period of several years, followed by a period of recruitment failure and high mortality. Future stock–recruitment studies should account for the effects of multi-year recruitment and year-class overlap.
Relationships between Acidity and Benthic Invertebrates of Low-Order Woodland Streams in the Adirondack Mountains, New York
Authors: Smith Michael E. , Wyskowski Barbara J. , Brooks Carol M. , Driscoll Charles T. , Cosentini Christina C.
Published: November 2009

Benthic invertebrates were collected during January, April, July, and October 1985 from three low-order woodland streams in the Adirondack Mountains, New York to evaluate relationships between acidity and stream invertebrates. Total invertebrate generic richness, generic diversity, Ephemeroptera density and richness, collector–gatherer richness, and scraper density and richness were positively correlated to stream pH. Ephemeroptera and Naididae (Oligochaeta) were absent from the acidic sampling site. Enchytraeid oligochaetes and Turbellaria were collected at all sites, but in significantly higher densities at the acidic site. Elmid beetles (Optioservus ovalis, Oulimnius latiusculus, Promoresia tardella), mayflies (Cinygmula and Baetis) and caddisflies (Glossosoma, Apatania, and Micrasema) were abundant at the sites where pH was highest and were absent from other sampling locales. Total invertebrate density was not decreased at the acidic site when compared with most other sampling sites. Multiple regression analyses revealed that pH and benthic organic matter were the two most important measured stream parameters in describing the variance of invertebrate communities in the three study streams.
phytoplankton Communities of Lakes Experimentally Acidified with Sulfuric and Nitric Acids
Authors: Findlay D. L. , Kasian S. E. M.
Published: November 2009

Additions of sulfuric acid to the South Basin and nitric acid to the North Basin of Lake 302 caused major changes in the phytoplankton communities. The basins were separated by a nylon-reinforced vinyl sea curtain. In the South Basin, below pH 5.6, species composition shifted from chrysophycean dominance to one of Dinophyceae. Diatoms and cyanophytes were eliminated below pH 5.3. Phytoplankton species diversity decreased as pH decreased. Total epilimnetic biomass was unchanged, except in late fall, when entrainment of dense layers of hypolimnetic species caused increases. The assemblage in the North Basin changed immediately upon additions of HNO3 to resemble systems experimentally fertilized with nitrogen. Chrysophycean dominance gave way to chlorophytes and dinoflagellates. Once pH decreased below 6.0, diatoms and cyanophytes were eliminated from the assemblage, as in the South Basin. Phytoplankton species diversity decreased, but total epilimnetic biomass remained unaffected.
Variation in Lake Water Temperature in the Nanticoke Region of Long Point Bay, Lake Erie, during the Open-Water Season
Authors: Dunstall T. G. , Lawler D. W. , Farooqui R. , Haymes G. T.
Published: November 2009

Lake water temperature on the north shore of Long Point Bay near Nanticoke (Lake Erie) over the years 1971–83 varied considerably during the lake warming cycle. Upwellings, resulting in temperature drops of 5–10°C over a 2–3 d period, were common from mid-May to mid-August. Warmer surface waters returned within 6 d (usually 3 d) following summer upwellings. In spring, the recovery times were variable but typically lasted longer, up to 25 d. Temperature fluctuations that exceeded 5°C but lasted less than 48 h were also frequent during the lake warming cycle. The progressive deepening of the epilimnion to the 12-m depth of Long Point Bay and the associated increase in the heat content of the Bay resulted in a stable temperature regime by mid-August. Diurnal heating and cooling of surface waters, by as much as 4°C, was apparent under calm conditions. Mean April–November temperatures varied by more than 2°C, reflecting annual variation in atmospheric warming.
Phosphorus and Nitrogen Limitation of Phytoplankton Growth in the Freshwaters of North America: A Review and Critique of Experimental Enrichments
Authors: Elser James J. , Marzolf Erich R. , Goldman Charles R.
Published: November 2009

While phosphorus is generally considered to be the primary nutrient limiting algal growth in lakes, limitation of algal growth by nitrogen has been observed in freshwater. It is also commonly observed that the most pronounced phytoplankton responses to enrichment occur when both N and P are added together. This led us to re-evaluate nitrogen's status as a secondary nutrient in freshwater through a systematic literature search. In our survey of enrichment bioassays, we found considerable deficiencies in the degree to which investigators have applied sufficient replication, performed and reported statistical tests, and assessed seasonal and spatial differences in algal nutrient limitation. Given these limitations, however, we found that combined N + P enrichment enhanced algal growth much more frequently and more substantially than did addition of N or P singly. On average, the frequency and degree of algal response did not differ for P vs. N enrichment. From our review of whole-lake fertilizations, we concluded that the roles of N and P in constraining algal growth at the whole-lake scale have not been completely separated. However, examination of the distribution between treatments (+N, +P, +N, and P) of lake-years in which substantial algal growth response occurred indicated that combined N and P enrichment was required to consistently produce substantial algal growth response. A more important role than has previously been recognized for N as a limiting nutrient in freshwaters is indicated. We suggest that greater attention should be given to both P and N in the future.
CALCULATION OF NUCLEAR LEVEL DENSITY PARAMETERS OF SOME LIGHT DEFORMED MEDICAL RADIONUCLIDES USING COLLECTIVE EXCITATION MODES OF OBSERVED NUCLEAR SPECTRA
Authors: OKUDUCU Ş. , AKTI N. N. , SARAÇ H. , BÖLÜKDEMIR M. H. , TEL E.
Published: November 2009

In this study the nuclear energy level density based on nuclear collective excitation mechanism has been identified in terms of the low-lying collective level bands near the neutron binding energy. Nuclear level density parameters of some light deformed medical radionuclides used widely in medical applications have been calculated by using different collective excitation modes of observed nuclear spectra. The calculated parameters have been used successfully in estimation of the neutron-capture cross section basic data for the production of new medical radionuclides. The investigated radionuclides have been considered in the region of mass number 40<A<100. The method used in the present work assumes equidistance spacing of the collective coupled state bands of the interest radionuclides. The present calculated results have been compared with the compiled values from the literatures for s-wave neutron resonance data.
LINEAR TWO-DIMENSIONAL MHD OF ACCRETION DISKS: CRYSTALLINE STRUCTURE AND NERNST COEFFICIENT
Authors: MONTANI GIOVANNI , BENINI RICCARDO
Published: November 2009

We analyse the two-dimensional MHD configurations characterising the steady state of the accretion disk on a highly magnetised neutron star. The model we describe has a local character and represents the extension of the crystalline structure outlined in Ref. 1, dealing with a local model too, when a specific accretion rate is taken into account. We limit our attention to the linearised MHD formulation of the electromagnetic back-reaction characterising the equilibrium, by fixing the structure of the radial, vertical and azimuthal profiles. Since we deal with toroidal currents only, the consistency of the model is ensured by the presence of a small collisional effect, phenomenologically described by a nonzero constant Nernst coefficient (thermal power of the plasma). Such an effect provides a proper balance of the electron force equation via nonzero temperature gradients, related directly to the radial and vertical velocity components.

We show that the obtained profile has the typical oscillating feature of the crystalline structure, reconciled with the presence of viscosity, associated to the differential rotation of the disk, and with a net accretion rate. In fact, we provide a direct relation between the electromagnetic reaction of the disk and the (no longer zero) increasing of its mass per unit time. The radial accretion component of the velocity results to be few orders of magnitude below the equatorial sound velocity. Its oscillating-like character does not allow a real matter in-fall to the central object (an effect to be searched into nonlinear MHD corrections), but it accounts for the outgoing of steady fluxes, favourable to the ring-like morphology of the disk.
QUANTUM CHEMICAL STUDY OF ELECTRONIC TRANSPORT PROPERTIES OF BIPHENYLDITHIOL MOLECULAR JUNCTION
Authors: SU WEN-YONG , JIN YAN-PING , WANG FENG
Published: November 2009

Applying the elastic scattering Green's function theory in combination with the frontier molecular orbital theory for describing the surface-molecule coupling and hybrid density-function theory for geometrical and electronic structure calculations, we successfully reproduce the current–voltage properties of the 4,4-biphenyldithiol molecular junction, which has been measured using a lock-in technique by Lee et al.1 We also analyze the conductance characteristics of different dimensional electrodes in contact with the molecular device, and we think that the one-dimensional formula is consistent with the experiment, and that the interaction between neighboring molecules will decrease the molecular orbital energies and draw the conductance peak positions closer to experimental results.
INVESTIGATION OF THIRD-ORDER NONLINEAR OPTICAL PROPERTIES OF BFDT-DOPED PMMA THIN FILMS USING Z-SCAN TECHNIQUE
Authors: FAN HELIANG , WANG XINQIANG , REN QUAN , LI TINGBIN , SUN JING , ZHANG GUANGHUI , XU DONG , SUN ZHIHUA , YU GANG
Published: November 2009

A series of polymeric thin films with BFDT (BFDT = 4,5-bis(foroylsulfanyl)-1,3-dithiole-2-thione) doped in PMMA (polymethylmethacrylate) were fabricated by means of spin-coating on quartz substrate. The third-order nonlinear optical properties of the films were investigated by Z-scan technique at 532 nm wavelength with 20 ps pulse width. The influences of doping concentration for third-order nonlinearity were also studied. A self-defocusing effect was observed from the Z-scan curves and the nonlinear refractive index of the film increases with the increase in doping concentration. Our results suggest that considerable nonlinear optical properties were found in BFDT. In addition, it was found that the nonlinear coefficient of the BFDT-doped PMMA thin film was about two orders of magnitude larger than that of homologous materials with organic solvents. By analysis, we can conclude that the material is a potential candidate for applications of nonlinear optics and can be considered in the fabrication of all-optical switching devices, etc.
EXPERIMENTAL STUDY OF SPATIAL NON-UNIFORMITIES IN A DUAL FREQUENCY CAPACITIVELY COUPLED PLASMA
Authors: ZHAO GUOLI , XU YONG , SHANG JIANPING , ZHU AIMIN , LU WENQI , WANG YOUNIAN
Published: November 2009

Radial non-uniformities of dual frequency capacitively coupled argon plasma were experimentally studied, using an optical emission spectroscopy probe, for different discharge pressures, discharge gaps, and frequencies and powers of the low frequency source. It was shown that the plasma emission profiles strongly depend on the working gas pressure and the lower frequency (LF) power. With the increasing LF power the emission profiles changed from a bell-shaped distribution at low LF power to a double-peak distribution at high LF power.
IMAGE MATCHING WITH A CAR-MOUNTED CAMERA ROBUST TO CHANGES IN IMAGING CONDITIONS
Authors: ENAMI NAOKO , UKITA NORIMICHI , KIDODE MASATSUGU
Published: November 2009

We propose a matching method for images captured at different times and under different capturing conditions. Our method is designed for change detection in streetscapes using normal automobiles that have an off-the-shelf car mounted camera and a GPS. Therefore, we are able to analyze low-resolution and low frame-rate images captured asynchronously. To cope with this difficulty, previous and current panoramic images are created from sequential images which are rectified based on the view direction of a camera, and are then compared. In addition, in order to allow the matching method to be applicable to images captured under varying conditions, (1) for different lanes, enlarged/reduced panoramic images are compared with each other, and (2) robustness to noises and changes in illumination is improved by the edge features. To confirm the effectiveness of the proposed method, we conducted experiments matching real images captured under various capturing conditions.
RECOGNIZING PERSONS CLIMBING FENCES
Authors: YU ELDEN , AGGARWAL J. K.
Published: November 2009

In this paper, we present two approaches to recognize a special type of human action, e.g. climbing a fence, from continuous monocular videos. Both approaches represent human activities as time series of discrete observations. In the first approach, we extract a feature vector from each frame, based on the relative configuration of human body parts against a fence. In the second approach, we propose a novel concept called "stable contact", to decompose the continuous human activities into adjacent but disjoint time intervals called primitive intervals. We then define a primitive motion unit (PMU) on each primitive interval with three attributes, thus converting each continuous activity into a sequence of PMUs. With the time series representations, we utilize Hidden Markov Model (HMM) techniques for recognition, including decoding in the first approach and searching in the second approach. Experimental results, on a set of image sequences with mixed human actions including walking and climbing a fence, show the effectiveness of the proposed methods. We compare the two approaches and discuss their applicability in different scenarios.
GEO-BASED AERIAL SURVEILLANCE VIDEO PROCESSING FOR SCENE UNDERSTANDING AND OBJECT TRACKING
Authors: XIAO JIANGJIAN , CHENG HUI , HAN FENG , SAWHNEY HARPREET
Published: November 2009

This paper presents an approach to extract semantic layers from aerial surveillance videos for scene understanding and object tracking. The input videos are captured by low flying aerial platforms and typically consist of strong parallax from non-ground-plane structures as well as moving objects. Our approach leverages the geo-registration between video frames and reference images (such as those available from Terraserver and Google satellite imagery) to establish a unique geo-spatial coordinate system for pixels in the video. The geo-registration process enables Euclidean 3D reconstruction with absolute scale unlike traditional monocular structure from motion where continuous scale estimation over long periods of time is an issue. Geo-registration also enables correlation of video data to other stored information sources such as GIS (Geo-spatial Information System) databases. In addition to the geo-registration and 3D reconstruction aspects, the other key contributions of this paper also include: (1) providing a reliable geo-based solution to estimate camera pose for 3D reconstruction, (2) exploiting appearance and 3D shape constraints derived from geo-registered videos for labeling of structures such as buildings, foliage, and roads for scene understanding, and (3) elimination of moving object detection and tracking errors using 3D parallax constraints and semantic labels derived from geo-registered videos. Experimental results on extended time aerial video data demonstrates the qualitative and quantitative aspects of our work.
INTELLIGENT SURVEILLANCE BASED ON NORMALITY ANALYSIS TO DETECT ABNORMAL BEHAVIORS
Authors: ALBUSAC JAVIER , VALLEJO DAVID , JIMENEZ-LINARES LUIS , CASTRO-SCHEZ J. J. , RODRIGUEZ-BENITEZ LUIS
Published: November 2009

Intelligent surveillance refers to using Artificial Intelligence techniques in order to improve surveillance and deal with semantic information obtained from low-level security devices. In this context, the use of expert knowledge may offer a more realistic solution when dealing with the design of a surveillance system. In this work, a conceptual framework based on normality analysis to detect abnormal behaviors by means of normality concepts is presented. A normality concept specifies how a certain object should ideally behave in a concrete environment depending on such a concept. The definition of the normal path concept is studied in depth in order to analyze behaviors in an outdoor environment.
SURVEILLANCE VIDEO INDEXING AND RETRIEVAL USING OBJECT FEATURES AND SEMANTIC EVENTS
Authors: LE THI-LAN , THONNAT MONIQUE , BOUCHER ALAIN , BRÉMOND FRANÇOIS
Published: November 2009

In this paper, we propose an approach for surveillance video indexing and retrieval. The objective of this approach is to answer five main challenges we have met in this domain: (1) the lack of means for finding data from the indexed databases, (2) the lack of approaches working at different abstraction levels, (3) imprecise indexing, (4) incomplete indexing, (5) the lack of user-centered search. We propose a new data model containing two main types of extracted video contents: physical objects and events. Based on this data model, we present a new rich and flexible query language. This language works at different abstraction levels, provides both exact and approximate matching and takes into account users' interest. In order to work with the imprecise indexing, two new methods respectively for object representation and object matching are proposed. Videos from two projects which have been partially indexed are used to validate the proposed approach. We have analyzed both query language usage and retrieval results. The obtained retrieval results analyzed by the average normalized ranks are promising. The retrieval results at the object level are compared with another state of the art approach.
DETECTING GHOST AND LEFT OBJECTS IN SURVEILLANCE VIDEO
Authors: LU SIJUN , ZHANG JIAN , FENG DAVID DAGAN
Published: November 2009

This paper proposes an efficient method for detecting ghost and left objects in surveillance video, which, if not identified, may lead to errors or wasted computational power in background modeling and object tracking in video surveillance systems. This method contains two main steps: the first one is to detect stationary objects, which narrows down the evaluation targets to a very small number of regions in the input image; the second step is to discriminate the candidates between ghost and left objects. For the first step, we introduce a novel stationary object detection method based on continuous object tracking and shape matching. For the second step, we propose a fast and robust inpainting method to differentiate between ghost and left objects by reconstructing the real background using the candidate's corresponding regions in the current input and background image. The effectiveness of our method has been validated by experiments over a variety of video sequences and comparisons with existing state-of-art methods.
A MACHINE LEARNING FRAMEWORK FOR REAL-TIME TRAFFIC DENSITY DETECTION
Authors: CHEN JING , TAN EVAN , LI ZHIDONG
Published: November 2009

Traffic flow information can be employed in an intelligent transportation system to detect and manage traffic congestion. One of the key elements in determining the traffic flow information is traffic density estimation. The goal of traffic density estimation is to determine the density of vehicles on a given road from loop detectors, traffic radars, or surveillance cameras. However, due to the inflexibility of deploying loop detectors and traffic radars, there is a growing trend of using video-content-understanding technique to determine the traffic flow from a surveillance camera. But difficulties arise when attempting to do this in real-time under changing illumination and weather conditions as well as heavy traffic congestions. In this paper, we attempt to address the problem of real-time traffic density estimation by using a stochastic model called Hidden Markov Models (HMM) to probabilistically determine the traffic density state. Choosing a good set of model parameters for HMMs has a significant impact on the accuracy of traffic density estimation. Thus, we propose a novel feature extraction scheme to represent traffic density, and a novel approach to initialize and construct the HMMs by using an unsupervised clustering technique called AutoClass. We show through extensive experiments that our proposed real-time algorithm achieves an average traffic density estimation accuracy of 96.6% over various different illumination and weather conditions.