bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessing Students' Mathematical Communication
Authors: Cai Jinfa , Jakabcsin Mary S. , Lane Suzanne
Published: March 2010

Assessment of students' mathematical communication through the use of open‐ended tasks and scoring procedures is addressed, as is the use of open‐ended tasks to assess students' mathematical communication by providing students opportunities to display their mathematical thinking and reasoning. Also, two scoring procedures (quantitative holistic scoring procedure and qualitative analytic scoring procedure) are described for examining students' communication skills.
Corporate Diversification, Relatedness, and Firm Value: Evidence from Korean Firms*
Authors: Bae Sung C. , Kwon Taek Ho , Lee Jang Woo
Published: March 2010

We examine the valuation effects of diversification activities for Korean firms by diversification type and the occasion of the Korean financial crisis. Employing a unique dataset of 2,894 firm‐years for the entire manufacturing industries, we find that diversification by Korean firms on average decreases firm value but its effect varies by the type of diversification. While unrelated diversification erodes firm value, related diversification is associated with a non‐negative effect on firm value. These valuation effects are more pronounced before the crisis than after the crisis. Our results also show an important role of a firm's affiliation to a large business group, known as chaebols, that related diversification by chaebol‐affiliated firms comes with a significant value gain. We further find that the different valuation effects of unrelated and related diversification are closely related to a firm's ownership concentration and financial leverage. Our results are robust to different samples and regression model specifications.
Volatility, Market Structure, and the Bid‐Ask Spread*
Authors: Chung Kee H. , Kim Youngsoo
Published: March 2010

We test the conjecture that the specialist system on the New York Stock Exchange (NYSE) provides better liquidity services than the NASDAQ dealer market in times of high return volatility when adverse selection and inventory risks are high. We motivate our conjecture from the observation that there is a designated specialist for each stock on the NYSE who is directly responsible for maintaining a reasonable level of liquidity (i.e., the bid‐ask spread) as the ‘liquidity provider of last resort’ whereas there is no such designated dealer on NASDAQ. Empirical evidence is consistent with our conjecture. In a similar vein, we show that the specialist system provides better liquidity than the dealer market in thin markets.
Option Pricing with Extreme Events: Using Câmara and Heston(2008)‘s Model*
Authors: Kim Sol
Published: March 2010

For the KOSPI 200 Index options, we examine the effect of extreme events for pricing options. We compare Black and Scholes (1973) model with Câmara and Heston (2008)'s options pricing model that allows for both big downward and upward jumps. It is found that Câmara and Heston (2008)'s extreme events option pricing model shows better performance than Black and Scholes (1973) model does for both in‐sample and out‐of‐sample pricing. Also downward jumps are a more important factor for pricing stock index options than upward jumps. It is consistent with the empirical evidence that reports the sneers or negative skews in the stock index options market.
The Dynamics of Diversification Discount*
Authors: Ahn Seoungpil
Published: March 2010

Using a sample of diversified firms over the period of 1980–2003, I investigate changes in the diversification discount over the two decades. The time‐series pattern of the diversification discount is created by the entrance and exit of discount firms. I find that the distribution of excess value can correctly predict the survivalship of a diversified firm. Discount firms are more likely to reverse their diversification within short time period. By contrast, the survival of diversification strategies among premium firms and focused firms is unrelated to the firms' excess values. After accounting for value effects, premium firms perform better than focused firms and discount firms. I interpret the results as evidence that excess value can correctly identify these firms that are successful and unsuccessful in their diversification.
Determinants of Corporate Bond Returns in Korea: Characteristics or Betas?*
Authors: Hong Woosun , Lee Seong‐Hyo , Park Young S.
Published: March 2010

This study investigates how the corporate bond's characteristics and Betas affect bond returns by using extensive Korean corporate bonds data from 2001 to the first half of 2007. Overall, our results indicate that bond characteristics provide significant explanations to excess returns while market factors (i.e., Betas) do not. It is strikingly different from the U.S. study of Gebhardt et al. (2005), which showed that market factors notably affect the excess returns of U.S. corporate bonds.
Earnings Uncertainty and Analyst Forecast Herding*
Authors: Song Minsup , Kim Doseong , Won Chaehwan
Published: March 2010

This study empirically investigates how a firm's earnings uncertainty affects analysts' herding behaviors in earnings forecasts. Trueman (1994) and Graham (1999) analytically predict that analysts have higher incentives to issue a herding forecast when a firm's earnings uncertainty is low. We test this analytical prediction using a proxy for bold forecasts used by Gleason and Lee (2003) and Clement and Tse (2005). We classify analysts' earnings forecasts as bold when an analyst's revised forecast is larger (or smaller) than both the analyst's own prior forecast and the mean consensus forecast of other analysts immediately prior to the analyst's forecast. Earnings uncertainty is measured by standard deviation of time‐serial earnings forecast errors. A logit regression result shows a positive relation between bold forecasts and earnings uncertainty after controlling for analyst characteristics, which is consistent with the prediction by Trueman (1994) and Graham (1999). We also find that as earnings uncertainty increases, the accuracy of analysts' bold forecasts relative to consensus forecast accuracy also increases. These results imply that analysts are active in producing new relevant information about firms when earnings uncertainty is higher.
The Price Premium of China A‐Shares over Hong Kong H‐Shares: A Further Visit of the Liquidity Hypothesis*
Authors: Lee Hing‐Wah
Published: March 2010

I examine the price premium between A‐shares and H‐shares using a sample of Hong Kong, Shenzhen, and Shanghai stock market intraday data in 2004. Following the market‐microstructure approach, I reinvestigate the liquidity hypothesis by incorporating spread and depth. The study generates two important results. First, China A‐shares on average provide better market liquidity than their Hong Kong H‐share counterparts do. Second, after controlling for traditional liquidity measures and variables related to competing hypotheses, the percentage differences in quoted spread and depth between A‐shares and H‐shares still explain significantly the price premium. Endogeneity between spread and depth does not affect the major findings.
International Transmission of Swap Market Movements: The U.S., Korea, and China*
Authors: Lee Hahn S. , Hong Woo‐Hyung
Published: March 2010

This paper investigates whether and to what extent the Korean and Chinese swap markets are linked to the US counterpart. We apply bivariate EGARCH models to daily closing mid‐rate data on swap maturities of 3, 5, and 10 years for the US, Korea, and China. We find that the US swap market has a major influence on the Korean and the Chinese swap markets. Strong evidence is found for the swap spread as well as volatility spillover effects from the US swap market to the Korean counterpart. On the other hand, the linkage between the US and Chinese swap markets turns out to be weak. This result indicates that the Chinese swap market, which opened on April 2006, is yet premature.
Regulatory Environment, Changing Incentives, and IPO Underpricing in the Korean Stock Market*
Authors: Shin Inseok
Published: March 2010

I examine the importance of price support regulation in explaining IPO underpricing in the Korean stock market from 2001 through 2007. In contrast to the US practice where price support is provided effectively at the cost of the issuing firms, the price support in Korea resulted in direct costs to the underwriters. I construct a simple model to capture this feature of the regulation where IPO prices are determined through the interaction of the maximizing behaviors of underwriters and issuers. In the model, three variables, namely, the expected post‐IPO price volatility, size of newly issued shares, and size of tradable shares, are specified to affect the opportunity costs of underpricing. When combined with the regulatory regime change in 2003, which lightened underwriters’ obligations towards price support, the model implies that the magnitudes of the relationships between the three variables and underpricing have decreased since 2003. I test the hypotheses and find supportive empirical results: the relationship of underpricing with the expected price volatility has changed from positive to insignificant; those with sizes of newly issued and tradable shares from insignificant to negative. The findings contrast with existing Korean studies that do not find any evidence that price support regulation decreased the opportunity cost of underpricing for underwriters. The results also illustrate a more general point that to fully understand underpricing in a given stock market, it is crucial to take into account the regulatory environment that systematically influences agents’ incentives to control or generate underpricing.
Information Uncertainty Risk and Seasonality in International Stock Markets
Authors: Kim Dongcheol
Published: March 2010

A parsimonious two‐factor model containing the market risk factor and a risk factor related to earnings information uncertainty has been developed to explain the seasonal regularity of January in international stock markets. This two‐factor model shows apparently stronger power in explaining time‐series behavior of stock returns and the cross‐section of average stock returns in all major developed countries than do the competing models. Furthermore, the arbitrage residual return in January, which is the difference in the average residual returns between the smallest and largest size portfolios, is statistically insignificant in all the countries. These results indicate that the risk factor related to earnings information uncertainty plays a special role in explaining the seasonal pattern of stock returns in January, and that January might be a month that potentially tends to differentially reward stocks having uncertain earnings information. It could be argued, therefore, that large returns in January might be a risk premium for taking information uncertainty risk concerning earnings and unexpected earnings surprises faced at the earnings announcement, and that the previously reported strong January seasonality in stock returns might result from the use of misspecified models in adjusting for risk.
A Note on the Convergence of Analytical Target Cascading With Infinite Norms
Authors: Han Jeongwoo , Papalambros Panos Y.
Published: March 2010

Analytical target cascading (ATC) is a multidisciplinary design optimization method for multilevel hierarchical systems. To improve computational efficiency, especially for problems under uncertainty or with strong monotonicity, a sequential linear programming (SLP) algorithm was previously employed as an alternate coordination strategy to solve ATC and probabilistic ATC problems. The SLP implementation utilizes L∞ norms to maintain the linearity of SLP subsequences. This note offers a proof that there exists a set of weights such that the ATC algorithm converges when L∞ norms are used. Examples are also provided to illustrate the effectiveness of using L∞ norms as a penalty function to maintain the formulation linear and differentiable. The examples show that the proposed method provides more robust results for linearized ATC problems due to the robustness of the linear programming solver.
Characteristic Matrices and Conceptual Design of Hydraulic Systems
Authors: Ma Wenyong , Wang Delun , Ting Kwun-Lon
Published: March 2010

The paper presents a new conceptual design method that is capable of generating large numbers of possible design concepts of hydraulic systems automatically for specified operation requirements. A hydraulic system is regarded as a set of single-action subsystems and each subsystem is formed by a set of basic transformation units representing hydraulic components and their usage patterns. The input and output energy characteristic states of a subsystem or basic transformation unit are represented by qualitative vectors related by a diagonal characteristic matrix. Each element of the matrix defines a simple transformation and the operation rules of these transformations are defined. The subsystem characteristic matrix is the product of the characteristic matrices of the basic transformation units. The characteristic matrices of all basic transformation units are identified and classified and the decomposition rules for subsystem characteristic matrices are established. Thus, the characteristic matrix of a subsystem can be successively decomposed into various sets of characteristic matrices of basic transformation units. Each set of such basic transformation units is the topological representation of a hydraulic system. By successive decomposition of a system characteristic matrix, a thorough conceptual design process for hydraulic systems is established. The proposed method is illustrated by examples.
Double-gate-driving field emission display panel with stacked-metalized-aperture structure
Authors: Luo Jie , Chen Jun , Deng S. Z. , Zhang Yu , Xu N. S.
Published: March 2010

To utilize high-performance nanoemitter cold cathode prepared by high-temperature direct-growth process, 4.5 in. field emission display based on double-gate driving principle has been fabricated. A stacked-metalized-aperture structure has been introduced to improve stability. This structure composes of two gate-plates and is different in terms of addressing behavior from previously reported single gate-plate structure. Device characteristics have been investigated in details and are found to comply in trend with simulated results. The upper gate is found having native focusing feature. The result is encouraging as the current structure is possible to achieve high-performance large-area display.
Multiple scattering Casimir force calculations: Layered and corrugated materials, wedges, and Casimir–Polder forces
Authors: Milton Kimball A. , Parashar Prachi , Wagner Jef , Cavero-Peláez I.
Published: March 2010

Various applications of the multiple scattering techniques to calculating the Casimir energy are described. These include the interaction between dilute bodies of various sizes and shapes, temperature dependence, interactions with multilayered and corrugated bodies, and new examples of exactly solvable separable bodies.
Potential contributions of noncontact atomic force microscopy for the future Casimir force measurements
Authors: Kim W. J. , Schwarz U. D.
Published: March 2010

Surface electric noise, i.e., the nonuniform distribution of charges and potentials on a surface, poses a great experimental challenge in modern precision force measurements. Such a challenge is encountered in a number of different experimental circumstances. The scientists employing atomic force microscopy (AFM) have long focused their efforts to understand the surface-related noise issues via variants of AFM techniques, such as Kelvin probe force microscopy or electric force microscopy. Recently, the physicists investigating quantum vacuum fluctuation phenomena between two closely spaced objects have also begun to collect experimental evidence, indicating a presence of surface effects neglected in their previous analyses. It now appears that the two seemingly disparate science communities are encountering effects rooted in the same surface phenomena. In this report, the authors suggest specific experimental tasks to be performed in the near future that are crucial not only for fostering needed collaborations between the two communities but also for providing valuable data on the surface effects in order to draw the most realistic conclusion about the actual contribution of the Casimir force (or van der Waals force) between a pair of real materials.
Investigation of multistack InAs/InGaAs/GaAs self-assembled quantum dots-in-double-well structures for infrared detectors
Authors: Sharma Yagya D. , Kutty M. N. , Shenoi R. V. , Barve Ajit V. , Myers S. , Shao J. , Plis E. , Lee S. , Noh S. , Krishna S.
Published: March 2010

The authors report the InAs/InGaAs/GaAs/AlGaAs quantum dots-in-double-well (D-DWELL) design, which has a lower strain per DWELL stack than the InAs/InGaAs/GaAs DWELLs thereby enabling the growth of many more stacks in the detector. The purpose of this study is to examine the effects of varying the number of stacks in the double DWELL detector on its device performance. The structures are grown by solid source molecular beam epitaxy on GaAs substrates. After fabrication of single pixel devices, a series of device measurements such as spectral response, dark current, total current, and responsivity were undertaken and the photoconductive gain and the activation energies were extracted. The goal of these experiments is not only to optimize the device performance by optimizing the number of stacks but also to investigate the transport properties as a function of the number of stacks.
Bola Motion
Authors: McCarthy Thomas
Published: March 2010

Toward the end of the AP® Physics C Mechanics course, I challenge my students to integrate many of the concepts they have learned in both the classroom and laboratory by completing the “Bola Lab.” The title is based on the Argentinean gaucho (cowboy) herding tool, the boleadora, or bola for short (see Fig. 1),1 which consists of two heavier weights attached to two longer cords and a lighter weight attached to a shorter cord, as shown in Fig. 2.2 The bola is held by the smaller ball and twirled in a horizontal plane around the head to give the balls momentum and then released. Being thrown in this manner arranges the two heavier weights to rotate and fly closer together as compared with a bola with equal weights and cord lengths.3 With practice, this will result in the pair hitting either side of the cattie's legs, and the lighter weight then swings around this instantaneous axis of rotation, thus wrapping up the animal's legs4,5 and capturing him. The weights are chosen so they do not harm but merely capture the animal.
The Role of Sign in Students' Modeling of Scalar Equations
Authors: Hayes Kate , Wittmann Michael C.
Published: March 2010

Helping students set up equations is one of the major goals of teaching a course in physics that contains elements of problem solving. Students must take the stories we present, interpret them, and turn them into physics; from there, they must turn that physical, idealized story into mathematics. How they do so and what problems lie along the way are a major source of difficulty for us as instructors. In this paper, we consider just one such difficulty, getting the plus and minus signs correct when setting a net force equal to mass times acceleration. Even in such simple equations, we find that students make common errors in how they connect the mathematics and the physics. Specifically, we have seen college physics students use physical and mathematical reasoning inconsistently when determining signs of terms in equations. The problem seems to lie in how a vector equation gets interpreted into a scalar equation (whose form depends on one's choice of coordinate system).
Instantaneous Velocity Using Photogate Timers
Authors: Wolbeck John
Published: March 2010

Photogate timers are commonly used in physics laboratories to determine the velocity of a passing object. In this application a card attached to a moving object breaks the beam of the photogate timer providing the time for the card to pass. The length L of the passing card can then be divided by this time to yield the average velocity (or speed) of the passing object: Vavg = L/t.
Misconceptions as necessary stepping stones
Authors: Blanton Patricia
Published: March 2010

I've been reading an online book called Ready, Set, Science! Putting Research to Work in K-8 Science Classrooms (www.nap.edu/catalog.php?record_id=11882) and have found the discussion very enlightening. I think that any beginning science teacher might want to look at this book for guidance in designing lessons and managing student discussions to help students become more thoughtful, productive, and independent learners. While the book gives examples of K-8 classrooms, the examples of classroom discourse could serve as a road map for teachers at any level who want to make their classrooms more student centered and a place where all learners are actively engaged.
The imploding antrum syndrome: an unusual cause of double vision
Authors: Stevens Karen , Omer Salah , Toocaram Brenda , Rich Philip , Almemar Ali
Published: March 2010

A 42-year-old man presented with a 3 day history of drooping of the right eyelid and intermittent double vision. He was found to have mechanical restriction of the left eye in elevation and MRI demonstrated an abnormality in the left maxillary sinus with descent of the left inferior rectus muscle. CT confirmed the diagnosis of ‘imploding antrum’ or ‘silent sinus’ syndrome. It was treated surgically with complete resolution of symptoms and signs.
Benthic Macrofaunal Production in the Bay of Fundy and the Possible Effects of a Tidal Power Barrage at Economy Point – Cape Tenny
Authors: Wildish D. J. , Peer D. L. , Greenberg D. A.
Published: March 2010

The distribution of macrofaunal productivity in the Bay of Fundy, inclusive of the upper Bay (Chignecto Bay and Minas basin) is presented. The data used in mapping are based on wet biomass from 266, 0.1- and 0.5-m2 grab samples, converted to annual productivity using a lifespan/annual turnover regression. Macrofaunal production of the subtidal area (11 149 km2) of the whole Bay of Fundy is estimated to be 212 × 104 t wet biomass∙yr−1 equivalent to 190 g wet wt∙m−2∙yr−1Production in the intertidal area (1437 km2), by contrast, is estimated to be 13 × 104 t wet biomass∙yr−1 or 92 g wet∙m−2∙yr−1. Possible qualitative macrofaunal changes resulting from building a tidal barrage between Economy Point and Cape Tenny are suggested on the basis of predicted physical changes, particularly tidal current speed, sediment type, and sediment bed stress. The only quantitative prediction possible with our biological data is that suspension-feeding animal production will be 17% less in the lower Bay of Fundy following barrage construction. This reduction is not significant at the 95% confidence level.
Nickel Ion Requirements for Autotrophic Growth of Several Marine Microalgae with Urea Serving as Nitrogen Source
Authors: Oliveira Luis , Antia Naval J.
Published: March 2010

Twelve marine species were tested for their competence to grow on urea as sole nitrogen source, and the influence of nickel ion on such urea utilization was determined. In those cases (six species) where good algal growth occurred in the seawater medium used without added nickel, the metal ion requirement was demonstrated by suppressing the algal growth with a chelator (citric acid) and testing for subsequent growth from addition of excess nickel. The results showed that a nickel requirement for urea utilization is of widespread occurrence among the microalgae tested. The concentrations of nickel tested in the laboratory were compared with the endogenous nickel levels reported for ocean waters, and it was concluded that these levels are generally sufficient to support an effective utilization of urea by most urease-producing algae. The value of chelation tests as a rapid, reliable method for the demonstration of the Ni2+ requirement is discussed.
Selective Predation by Procladius in an Arctic Alaskan Lake
Authors: Hershey Anne E.
Published: March 2010

In arctic Alaskan Toolik Lake, the predatory larval chironomid Procladius spp. (Diptera) feeds on a variety of benthic organisms including algae, other chironomids, and microcrustaceans. Laboratory experiments with two similar-sized chironomid prey, instar I Chironomus and instar II Paratanytarsus, showed that Procladius was a more effective predator on Chironomus. The two prey used different foraging behaviors; Chironomus grazed an area around its tube but Paratanytarsus remained inside its tube. In a field experiment, in which Procladius density was manipulated, a decrease in prey density occurred in the chironomid group Orthocladiinae, which could be attributed to Procladius predation. Gut analyses of Procladius showed that a higher proportion of Orthocladiinae was eaten than could be predicted from their abundance. Orthocladiinae, which typically graze around tubes, may have been more susceptible to Procladius because of behavioral characteristics.
Survival from Sea Lamprey (Petromyzon marinus) Predation by Two Strains of Lake Trout (Salvelinus namaycush)
Authors: Swink William D. , Hanson Lee H.
Published: March 2010

We tested the hypothesis that the better survival of the Seneca Lake strain of lake trout (Salvelinus namaycush) in Lake Ontario resulted from their greater resistance than other stocked strains to sea lamprey (Petromyzon marinus) predation. No significant difference was found in the survival of Marquette and Seneca Lake strains of Lake trout subjected to single sea lamprey attacks in the laboratory. Of 85 Marquette strain lake trout, 44% died as a direct result of sea lamprey predation, 20% died of undetermined causes, and 36% survived; for 90 lake trout of the Seneca Lake strain, the respective percentages were 39, 21, and 40. The location of sea lamprey attachment on the lake trout was not a factor in mortality, which was significantly higher at water temperatures of 15.6–17.8 °C than at 0.6–15.6 °C. Our study suggested that the seemingly greater survival rate of Seneca Lake fish in Lake Ontario probably resulted from differences in behavior or environmental preferences that decreased their exposure to sea lamprey attacks.
Modelling the Increase in Variance of Fish Weight
Authors: Arnason A. N. , Papst M. H. , Hopky G. E.
Published: March 2010

A simple model is described that is very effective in accounting for the variance in fish weights in groups of fish grown under controlled environmental conditions. The model explains the increase in variation over time in terms of final weight and the time required to reach this weight and is independent of initial weight and feeding rate. Results from experiments with rainbow trout (Oncorhynchus mykiss) and Arctic char (Salvelinus alpinus) were used to confirm the model's fit and to demonstrate how temperature effects can be incorporated. We discuss the use of the model for prediction and for testing for genetic or environmental effects on variation and for quantifying such effects on variance over time.
Influence of Dissolved Organic Carbon, pH, and Microbial Respiration Rates on Mercury Methylation and Demethylation in Lake Water
Authors: Miskimmin Brenda M. , Rudd John W. M. , Kelly Carol A.
Published: March 2010

Effects of changes in DOC concentrations, pH, and microbial respiration rates on specific rates of mercury methylation and demethylation in lake water were studied using radioisotopic techniques. Increased concentrations of DOC resulted in decreased specific rates of net methylation, possibly as a result of complexation of inorganic mercury with DOC. A reduction in pH from 7.0 to 5.0 had the greatest effect, causing large to moderate increases in net methylation rate at both low and high DOC concentrations (500–2600 μM). Rates of respiration (indicative of general rates of microbial activity), which were insensitive to pH change over the range tested (5.0–7.0), had the smallest effect on net methyl mercury production rates. We propose the following explanations for three situations in which high mercury concentrations are commonly found in fish. (1) in acidified dilute clear-water lakes, high fish mercury concentrations may be a result of enhanced in-lake methylation; (2) in brown-water circumneutral lakes, where in-lake methylation is inhibited by high DOC concentrations, terrestrial inputs of methyl mercury may be most important; and (3) in brown-water, low-pH lakes, both in-lake and terrestrial sources of methyl mercury may contribute to elevated mercury concentrations in fish.
Responses of the Freshwater AmphipodHyalella aztecato Environmental Acidification
Authors: Grapentine Lee C. , Rosenberg David M.
Published: March 2010

Effects of acidification on the freshwater amphipod Hyalella azteca were investigated by examining the role of pH on natural distribution of the species in 30 northwestern Ontario lakes and by determining its responses to acidification in a series of field and laboratory experiments. The amphipod was absent from all five lakes that had pH 5.03–5.40 or Ca concentration < 1.24 mg/L and was present in 23 of the 25 remaining lakes that had pH > 6.0 and Ca > 1.24 mg/L. In the field and laboratory experiments, amphipods transplanted to acidified lakes (pH 5.45, 5.66) or held in 500-L bags [Formula: see text] or 4-L aquaria [Formula: see text] showed lower survival than those held in corresponding neutral-pH, control treatments (P < 0.05). Neonate H. azteca were less tolerant of low pH than those in later life-history stages (P < 0.05). Populations of H. azteca will decline in habitats where the pH remains < 5.8, a condition extant in a substantial proportion of lakes in eastern North America.
Planktivorous Baltic Herring (Clupea harengus) Prey Selectively on Reproducing Copepods and Cladocerans
Authors: Flinkman Juha , Vuorinen Ilppo , Aro Eero
Published: March 2010

Plankton and Baltic herring (Clupea harengus) were sampled simultaneously at nine sites in the northern Baltic Sea and Gulf of Bothnia. The stomachs from 45 herring and 54 plankton samples were analysed. The prey consisted mainly of adult mesozooplankters: copepods and cladocerans. Larger zooplankters (mysids and amphipods) were very rare in the stomachs as were the younger stages (copepodids) of copepods. The stomach contents of the fish changed from brackish water and neritic plankton species in the northern Baltic Proper to limnic species in the northern part of the Bothnian Sea. The diversity of plankton species decreased along with the salinity from south to north. Comparison of the plankton samples and herring stomach contents showed that prey with a large body size was selected as food. Generally this resulted in female copepods being chosen, since they are larger than males of the same species. Especially preferred food items were species and stages which carried conspicuous egg sacs (Eurytemora affinis females) or pigmented eggs and embryos (Bosmina longispina, Podon spp). Our results suggest that the Baltic herring is capable of exerting a regulative effect on the prey population comparable with that found in freshwater planktivores.
How Much Acidification Has Occurred in Adirondack Region Lakes (New York, USA) since Preindustrial Times?
Authors: Cumming B. F. , Smol J. P. , Kingston J. C. , Charles D. F. , Birks H. J. B. , Camburn K. E. , Dixit S. S. , Uutala A. J. , Selle A. R.
Published: March 2010

Preindustrial and present-day lake water pH, acid neutralizing capacity (ANC), total monomeric aluminum (Alm), and dissolved organic carbon (DOC) were inferred from the species composition of diatom and chrysophyte microfossils in the tops (present-day inferences) and bottoms (pre-1850 inferences) of sediment cores collected from a statistically selected set of Adirondack lakes. Results from the study lakes were extrapolated to a predefined target population of 675 low-alkalinity Adirondack region lakes. Estimates of preindustrial to present-day changes in lake water chemistry show that approximately 25–35% of the target population has acidified. The magnitude of acidification was greatest in the low-alkalinity lakes of the southwestern Adirondacks, an area with little geological ability to neutralize acidic deposition and receives the highest annual average rainfall in the region. We estimate that ~80% of the target population lakes with present-day measured pH [Formula: see text] and 30–45% of lakes with pH between 5.2 and 6.0 have undergone large declines in pH and ANC, and concomitant increases in [Alm]. Estimated changes in [DOC] were small and show no consistent pattern in the acidified lakes. This study provides the first statistically based regional evaluation of the extent of lake acidification in the Adirondacks.
Allozyme Genotype and Differential Resistance to Mercury Pollution in the Caddisfly,Nectopsyche albida. I. Single-Locus Genotypes
Authors: Benton Michael J. , Guttman Sheldon I.
Published: March 2010

The caddisfly, Nectopsyche albida, was exposed to 0.6 mg mercury nitrate/L for 72 h and individual times to death recorded. All individuals were analyzed electrophoretically at six polymorphic loci. Time to death differed significantly among genotypes at the phosphoglucomutase and two alcohol dehydrogenase loci and among levels of heterozygosity. There is substantial evidence suggesting that many taxa possess allozyme genotypes exhibiting differential sensitivity to anthropogenic contaminants and natural stressors. Elimination of sensitive genotypes may reduce the ability of impacted populations to recover from additional impacts and may lessen the likelihood that they will adapt to slowly changing environmental conditions. Accordingly, we emphasize that (1) genetic standardization of bioassay organisms is necessary to assure consistency of results among testing facilities, (2) genetic monitoring may be a more sensitive method than numerical censusing to detect low levels of anthropogenic pollution, and (3) loss of genetic variation may hinder population persistence.
Allozyme Genotype and Differential Resistance to Mercury Pollution in the Caddisfly, Nectopsyche albida. II. Multilocus Genotypes
Authors: Benton Michael J. , Guttman Sheldon I.
Published: March 2010

While a number of papers document that sensitivity to pollution is correlated with single-locus genotype, only one has addressed associations with multilocus complexes. We exposed larval caddisflies, Nectopsyche albida, to inorganic mercury and recorded individual times to death, genetically characterized each individual at six polymorphic loci by starch gel electrophoresis, and tested the effects of multilocus genotype on time to death. Two two-locus complexes and two three-locus complexes were significantly correlated with survival time. This supports earlier studies that monitoring multilocus and single-locus genotype frequencies may be useful in detecting and measuring environmental impacts; however, we disagree that variation in survival time among genotypes per se supports selectionist theory, because no heritability of resistance has been demonstrated. We also disagree that enzyme systems not exhibiting such variation are nonadaptive and discuss how the elimination of sensitive multilocus genotypes may hinder population persistence.
A Multivariate Model for Predicting Population Fluctuations of Dreissena polymorpha in North American Lakes
Authors: Ramcharan Charles W. , Padilla Dianna K. , Dodson Stanley I.
Published: March 2010

The European zebra mussel, Dreissena polymorpha (Pallas), has recently been introduced to North American freshwaters. Dreissena exhibits a wide range of population dynamics among different European lakes. In some lakes, long-term population size is fairly constant, while populations in other lakes can fluctuate greatly from year to year. Assessments of the potential ecological and economic effects of Dreissena in North America will be affected if populations show large interannual fluctuations in abundance. We develop a multivariate model for predicting population dynamics of Dreissena in novel lake systems. Our model uses the limnological differences between lakes with constant populations of Dreissena and those with variable populations to identify variables that may determine population dynamics. We find that lakes with more constant populations tend to have larger surface areas, lower levels of calcium, and higher levels of phosphate (PO4) compared with lakes with more variable populations.
Predation Risk, Prey Behavior, and Feeding Rate in Daphnia pulex
Authors: Ramcharan Charles W. , Dodson Stanley I. , Lee Jason
Published: March 2010

Exposure to chemical exudates from the planktonic invertebrate predator Chaohorus americanus causes the prey Daphnia pulex to migrate upwards in the water column of laboratory experimental chambers. This behavior is an antipredator defense that results in spatial separation of Daphnia from Chaoborus, since this predator tends to remain near the bottom of the chambers. We test the effects of prey vulnerability, genotype, prior exposure to predators, and predator density on antipredator behavior of D. pulex. To study differences in vulnerability, we compared two genotypes of Daphnia that differed in their ability to produce a morphological defense (growth of neck spines) when exposed to Chaohorus chemical. Overall, behavioral responses to Chaoborus were stronger at higher predator densities. Juvenile Daphnia that are most vulnerable to Chaoborus predation had stronger responses than the less vulnerable adults. Neither genetically determined ability to produce neck spines nor phenotypic expression of neck spines affected strength of antipredator behavior. Vertical migration to avoid Chaoborus may have an ecological cost. Presence of Chaoborus reduced ingestion rates of juvenile Daphnia at low food levels (5 × 103 algal cells∙mL−1). Feeding experiments also showed differences in feeding characteristics of two different clones of D. pulex.
Role of Temperature, Dissolved Oxygen, and Backwaters in the Winter Survival of Freshwater Drum (Aplodinotus grunniens) in the Mississippi River
Authors: Bodensteiner Leo R. , Lewis William M.
Published: March 2010

Annual winter impingement of large numbers of freshwater drum (Aplodinotus grunniens) on screens of a power station intake on the Mississippi River led to an investigation of the cause of impingement. Impingement occurred most abundantly in winter and early spring and primarily involved juvenile fish. Pronounced drift of moribund and dead fish was found in the main channel above and below the power station in late winter. Laboratory studies indicated that juvenile freshwater drum became disoriented, incapacitated, and suffered increased mortality as water temperature dropped to 1 °C and below. In winter and early spring, temperatures were 0 °C in the main and side channels of the river, but pockets of water above 1 °C existed in some backwaters. Dissolved oxygen concentrations declined through the winter, becoming very low in some backwaters. An aggregation of fishes including freshwater drum was observed in the warmer backwaters. Variations in river flow and dissolved oxygen depletion in some backwaters were postulated to cause periodic disruption of the thermal refuges and an associated appearance of incapacitated and dead juvenile freshwater drum in the drift. If man-induced changes to the river eliminate backwater winter refuges, the ichthyofauna of the river could ultimately be altered.
Influence of Lake pH and Macrograzers on the Distribution and Abundance of Nuisance Metaphytic Algae in Ontario, Canada
Authors: France Robert L. , Welbourn Pamela M.
Published: March 2010

Thirty-six softwater lakes in central Ontario were sampled during 1988 to determine the relationship between metaphytic Zygnematacean algae and lake pH and the degree of complementarity between the presence of metaphyton and that of crayfish and tadpoles. A stratified sequential sampling program was developed to quantitatively measure and to objectively categorize average metaphyton abundance for each lake. A significantly greater proportion of lakes below pH 6 were found to contain extensive accumulations of metaphyton compared with lakes above pH 6. Lake pH and alkalinity were significantly correlated with metaphyton abundance. Macro-grazer density did not significantly influence the presence or absence of metaphyton, but reduced metaphyton abundance in those lakes which, because of their low pH or shallow depth, were predisposed to its accumulation. Managerial implications regarding the stocking of crayfish or tadpoles to limit the nuisance proliferation of metaphyton, and the importance of predaceous fishes in structuring this interaction, are discussed.
RDF(S) INTEROPERABILITY RESULTS FOR SEMANTIC WEB TECHNOLOGIES
Authors: GARCÍA-CASTRO RAÚL , GÓMEZ-PÉREZ ASUNCIÓN
Published: March 2010

Interoperability among different development tools is not a straightforward task since ontology editors rely on specific internal knowledge models which are translated into common formats such as RDF(S). This paper addresses the urgent need for interoperability by providing an exhaustive set of benchmark suites for evaluating RDF(S) import, export and interoperability. It also demonstrates, in an extensive field study, the state-of-the-art of interoperability among six Semantic Web tools. From this field study we have compiled a comprehensive set of practices that may serve as recommendations for Semantic Web tool developers and ontology engineers.
IMPACT OF INITIAL CONDITIONS ON NEW VENTURE SUCCESS: A LONGITUDINAL STUDY OF NEW TECHNOLOGY-BASED FIRMS
Authors: GAO JIAN , LI JUN , CHENG YUAN , SHI SHUDE
Published: March 2010

This article examines the relationship between initial conditions and new venture performance. The study uses a longitudinal study of 92 new ventures in Beijing Overseas Students Pioneer Park at Haidian. This study finds that new venture performance is significantly impacted by the venture's initial conditions. Additionally, the effects of initial conditions are found to decrease as the entrepreneurial process continues. It is also found that new venture performance is impacted more significantly by factors relating to entrepreneurial quality and characteristics of the venture.
SEIZING THE OPPORTUNITY OF PARADIGM SHIFTS: CATCH-UP OF CHINESE ICT FIRMS
Authors: WU XIAOBO , ZHANG WEI
Published: March 2010

The emergence of latecomer firms from East Asia in high-technology sectors is one of the most striking phenomena of world economy in the past decades. However, while most literature focuses on the catch-up of Korea and Taiwan, we know relatively little about the practices in China, especially the firm-level experiences. Based on in-depth case analyses of three Chinese ICT firms from exploratory and evolutionary perspectives, we attempt to locate the window of opportunity for Chinese ICT firms to catch up with forerunners and identify strategies they employed to seize the window of opportunity. Our research findings suggest that paradigm shifts provided these latecomers with an opportunity to penetrate the market and universal standards or new technologies from other domains serve as the window of opportunity for latecomers to surpass forerunners. This study also reveals that technology-market combination as well as other strategies including niche market proposition, service innovation, collaborative R&D and leveraging complementary technologies can be utilized as effective approaches to realize catch-up.
PERIODIC SOLUTION FOR GENERALIZED HIGH-ORDER DELAY DIFFERENTIAL EQUATIONS
Authors: Cheng Zhibo , Ren Jingli , Siegmund Stefan
Published: March 2010

In this paper we consider a generalized n-th order delay differential equation, by applying Mawhin's continuation theory and some new inequalities, we obtain sufficient conditions for the existence of periodic solutions. Moreover, an example is given to illustrate the results.
DETERMINANTS OF SEVERAL MATRICES ASSOCIATED WITH PASCAL'S TRIANGLE
Authors: Moghaddamfar A. R.
Published: March 2010

Pascal's triangle is one of the most well-known arithmetical triangles and has many wonderful properties. This triangle may be rearranged so that one can consider various matrices. When these matrices are squares, we can discuss their determinants. Our purpose of this article is to study the determinants of square matrices related to Pascal's triangle where the determinants are equal to an entry in a particular place. We also consider the square matrices whose determinants are related to their dimensions only.
WEIGHTED GRIDS IN COMPLEX JORDAN* TRIPLES
Authors: STACHÓ L. L.
Published: March 2010

Weighted grids are linearly independent sets {gw : w ∈ W} of signed tripotents in Jordan* triples indexed by figures W in real vector spaces such that {gugvgw} ∈ ℂgu-v+w (= 0 if u - v + w ∉ W). They arise naturally as systems of weight vectors of certain abelian families of Jordan* derivations. Based on Neher's grid theory, a classification of association free non-nil weighted grids is given. As a first step beyond the setting of classical grids, the complete list of complex weighted grids of pairwise associated signed tripotents indexed by ℤ2 is established.
THE CONNECTED STABLE RANK FOR BANACH *-ALGEBRAS INVOLVING ISOMETRIES
Authors: Sudo Takahiro
Published: March 2010

It is shown that the connected stable rank of a unital Banach *-algebra containing two isometries with orthogonal ranges is infinity. Several consequences as its applications and variations are also obtained.
Semantic-less coordination of power management and application performance
Authors: Kansal Aman , Liu Jie , Singh Abhishek , Nathuji Ripal , Abdelzaher Tarek
Published: March 2010

A computer system often has multiple power management modules controlling diffierent power knobs. Uncoordinated operation of these knobs not only leads to suboptimal operation but may also cause unsafe behaviors. Coordination methods have thus been proposed to jointly control the power knobs and performance. However, in many systems, such joint design is not feasible due to lack of visibility into all modules to be coordinated. This occurs, for instance, in commodity software that runs on multiple platforms, andemerging cloud hosted applications that operate on platforms outside developers' control and alongside unknown other workloads. We propose an approach for semantics-free coordination where power-performance management can be performed within each module without semantic knowledge regarding other modules.
Considering the frequency dimension into on demand adaptive algorithms
Authors: Cansado Jacinto C.A. , Pereira João H.S. , Midorikawa Edson T.
Published: March 2010

Efficient memory usage in high performance timesharing computing systems is a considerable challenge. Some research areas on adaptive algorithms concerning memory page replacement, analyze the memory access behavior seeking to store the pages that will be used in a near future and discarding the others. This is important due to the high cost of treating page faults. The proposal is to analyze the influence of page access frequency on adaptive algorithms, using its structure and applying page replacement with access frequency analysis, as a function of its execution state. The comparative performance analysis is conducted by using trace files that represent different memory access behaviors.