bluuebunny/crossref_metadata_2025 huggingface dataset:
Multiphysics Simulation of Electrochemical Machining Process for Three-Dimensional Compressor Blade
Authors: Fujisawa Toshiaki , Inaba Kazuaki , Yamamoto Makoto , Kato Dai
Published: August 2008

Electrochemical machining (ECM) is an advanced machining technology. It has been applied in highly specialized fields such as aerospace, aeronautics, and medical industries. However, it still has some problems to be overcome. The efficient tool design, electrolyte processing, and disposal of metal hydroxide sludge are the typical issues. To solve such problems, computational fluid dynamics is expected to be a powerful tool in the near future. However, a numerical method that can satisfactorily predict the electrolyte flow has not been established because of the complex nature of flows. In the present study, we developed a multiphysics model and the numerical procedure to predict the ECM process. Our model and numerical procedure satisfactorily simulated a typical ECM process for a two-dimensional flat plate. Next, the ECM process for a three-dimensional compressor blade was simulated. Through visualization of the computational results, including the multiphase flow, and thermal and electric fields between the tool and the blade, it is verified that the present model and numerical procedure could satisfactorily predict the final shape of the blade.
An Analytical Method for Dielectrophoresis and Traveling Wave Dielectrophoresis Generated by an n-Phase Interdigitated Parallel Electrode Array
Authors: Song Hongjun , Bennett Dawn J.
Published: August 2008

In this paper, we present an analytical method for solving the electric potential equation with the exact boundary condition. We analyze the dielectrophoresis (DEP) force with an n-phase ac electric field periodically applied on an interdigitated parallel electrode array. We compare our analytical solution with the numerical results obtained using the commercial software CFD-ACE. This software verifies that our analytical method is correct for solving the problem. In addition, we compare the analytical solutions obtained using the exact boundary conditions and the approximate boundary conditions. The comparison shows that the analytical solution with the exact boundary condition gives a more accurate analysis for DEP and traveling wave DEP forces. The DEP forces of latex beads are also investigated with different phase arrays for (n=2,3,4,5,6).
Drop Formation in Non-Newtonian Jets at Low Reynolds Numbers
Authors: Dravid V. , Loke P. B. , Corvalan C. M. , Sojka P. E.
Published: August 2008

The objective of this study was to develop an experimentally verified computational model that accurately predicts evolution of shear-thinning liquid jets. A secondary objective was to investigate the formation of satellite drops and to determine conditions under which their diameter can be controlled. The model employs the Galerkin finite/element approach to solve the complete two-dimensional set of axisymmetric governing equations and the corresponding kinematic and dynamic boundary conditions at the free surface. The effect of shear-thinning behavior on breakup was studied in detail for the case of an infinitely long non-Newtonian jet. It was found that shear-thinning behavior may be useful in controlling satellite drop sizes. (We observe that increasing the shear-thinning behavior at Re∼5 leads to an initial increase in the satellite drop size, followed by a subsequent decrease.) Comparison of model predictions with experimental data is presented for the case of a shear-thinning non-Newtonian jet. The experimental liquid was pumped through a capillary and drop shapes obtained using a high speed camera. The experimentally obtained shapes were compared to those predicted by the model and found to be in good agreement.
Ecological level analysis of the relationship between smoking and residential-fire mortality
Authors: Diekman S T , Ballesteros M F , Berger L R , Caraballo R S , Kegler S R
Published: August 2008

Objectives:

To examine the association between tobacco smoking and residential-fire mortality and to investigate whether this association is explained by the confounding effects of selected socioeconomic factors (ie, educational attainment and median household income).

Design:

An ecological analysis relating state-level residential-fire mortality to state-level percentages of adults who smoke was conducted. Negative binomial rate regression was used to model this relationship, simultaneously controlling for the selected socioeconomic factors.

Results:

After educational attainment and median household income had been controlled for, smoking percentages among adults correlated significantly with state-level, population-based residential-fire mortality (estimated relative rate for a 1% decrease in smoking = 0.93; 95% CI 0.89 to 0.97).

Conclusions:

Mortality from residential fires is high in states with high smoking rates. This relationship cannot be explained solely by the socioeconomic factors examined in this study.
Improving the predictive ability of the ICD-based Injury Severity Score
Authors: Davie G , Cryer C , Langley J
Published: August 2008

Objective:

To assess whether the use of integrated hospitalization and mortality data sources and/or the inclusion of comorbidity improve the predictive ability of the International Classification of Disease (ICD)-based Injury Severity Score (ICISS).

Design:

Models using either the ICISS based solely on hospital discharge data or one of nine modified ICISSs as the predictor variable were assessed on their ability to predict survival using logistic regression modeling.

Setting:

New Zealand.

Patients or subjects:

Inpatients, with an S00–T89 ICD-10-AM principal diagnosis, and fatalities, with any S00–T89 ICD-10-AM diagnosis, occurring in 2000–2003.

Interventions:

None.

Main outcome measures:

Models were compared in terms of their discrimination (concordance), calibration, and goodness-of-fit.

Results:

186 835 cases including 9968 deaths met the inclusion criterion. The modified ICISS that included both mortality data and Charlson comorbid conditions at the ICD-10-AM level had the best concordance and high calibration. Calibration curves indicated that scores using hospital discharge data only to calculate survival risk ratios underestimated mortality, whereas scores using hospital discharge and mortality data overestimated mortality.

Conclusions:

Valid measurement of injury severity is important for both meaningful research and surveillance and to assist in classifying information to meet specific injury policy, prevention, and control needs. This study suggests that the predictive ability of ICISS would be improved if both mortality and comorbidity data were included in its calculation.
Cost-effectiveness of traffic enforcement: case study from Uganda
Authors: Bishai D , Asiimwe B , Abbas S , Hyder A A , Bazeyo W
Published: August 2008

Background:

In October 2004, the Ugandan Police department deployed enhanced traffic safety patrols on the four major roads to the capital Kampala.

Objective:

To assess the costs and potential effectiveness of increasing traffic enforcement in Uganda.

Methods:

Record review and key informant interviews were conducted at 10 police stations along the highways that were patrolled. Monthly data on traffic citations and casualties were reviewed for January 2001 to December 2005; time series (ARIMA) regression was used to assess for a statistically significant change in traffic deaths. Costs were computed from the perspective of the police department in $US 2005. Cost offsets from savings to the health sector were not included.

Results:

The annual cost of deploying the four squads of traffic patrols (20 officers, four vehicles, equipment, administration) is estimated at $72,000. Since deployment, the number of citations has increased substantially with a value of $327 311 annually. Monthly crash data pre- and post-intervention show a statistically significant 17% drop in road deaths after the intervention. The average cost-effectiveness of better road safety enforcement in Uganda is $603 per death averted or $27 per life year saved discounted at 3% (equivalent to 9% of Uganda’s $300 GDP per capita).

Conclusion:

The costs of traffic safety enforcement are low in comparison to the potential number of lives saved and revenue generated. Increasing enforcement of existing traffic safety norms can prove to be an extremely cost-effective public health intervention in low-income countries, even from a government perspective.
The Yorkhill CHIRPP story: a qualitative evaluation of 10 years of injury surveillance at a Scottish children’s hospital
Authors: Shipton D , Stone D H
Published: August 2008

Background:

The Canadian Hospitals Injury Reporting and Prevention Program (CHIRPP) is an emergency department-based injury surveillance system that was devised in Canada and has been in operation since 1990. CHIRPP was imported to Glasgow’s Royal Hospital for Sick Children at Yorkhill in 1996 and ran for 10 years.

Objective:

To critically review CHIRPP at Yorkhill (Y-CHIRPP). The following two key questions were posed. (1) Did Y-CHIRPP fail, and, if so, why? (2) What generalisable lessons can be learned about injury surveillance?

Methods:

A retrospective qualitative review of Y-CHIRPP was carried out. In gathering information, the aims were to: (a) describe the processes involved in running Y-CHIRPP; (b) identify changes made to that process over the 10 years; (c) determine the strengths and weaknesses of Y-CHIRPP.

Results:

Taken together, and with reference to the WHO attributes of a good surveillance system, the findings suggest that Y-CHIRPP largely met the criteria of simplicity, flexibility, and acceptability. Criteria that were not, or only intermittently, met were reliability, utility, sustainability, and timeliness.

Conclusions:

Y-CHIRPP was, at best, a partial success. To maintain the viability of an injury surveillance system and to secure the long-term support of hospital staff, it is important that the system is perceived as an injury prevention service tool and not a research method. Experience with Y-CHIRPP suggests that injury surveillance requires three supporting posts: an emergency department staff member, a data analyst, and someone with responsibility for developing and/or lobbying for the implementation of preventive measures.
Examining the sensitivity of an injury surveillance program using population-based estimates
Authors: Macpherson A K , White H L , Mongeon S , Grant V J , Osmond M , Lipskie T , Mackay M J
Published: August 2008

This study uses population-based estimates to assess the sensitivity and representativeness of an injury surveillance system using a 1-year population-based approach. Data from the Ottawa Canadian Hospitals Injury Reporting and Prevention Program (CHIRPP) site (Children’s Hospital of Eastern Ontario) were compared with those from six expansion sites. The overall sensitivity of CHIRPP was 43% of all treated injuries and 57% of injuries treated at emergency departments. CHIRPP was less likely to be representative for older children and more likely to capture children with more severe injuries. The limitations related to using CHIRPP for representing population-based injury remain fairly stable over time. A one-time population-based sample can provide useful information to add to routinely collected injury surveillance.
It takes a village to prevent falls: reconceptualizing fall prevention and management for older adults
Authors: Ganz D A , Alkema G E , Wu S
Published: August 2008

Systematic evidence reviews support the efficacy of physical activity programs and multifactorial strategies for fall prevention. However, community settings in which fall prevention programs occur often differ substantially from the research settings in which efficacy was first demonstrated. Because of these differences, alternative approaches are needed to judge the adequacy of fall prevention activities occurring as part of standard medical care or community efforts. This paper uses the World Health Organization Innovative Care for Chronic Conditions (ICCC) framework to rethink how fall prevention programs might be implemented routinely in both medical and community settings. Examples of innovative programs and policies that provide fall prevention strategies consistent with the ICCC framework are highlighted, and evidence where available is provided on the effects of these strategies on processes and outcomes of care. Finally, a “no wrong door” approach to fall prevention and management is proposed, in which older adults who are found to be at risk of falls in either a medical or community setting are linked to a standard fall risk evaluation across three domains (physical activity, medical risks, and home safety).
An empirical approach for defining acceptable levels of risk: a case study in team sports
Authors: Fuller C W , Ward C J
Published: August 2008

Objectives:

To determine acceptable levels of risk in sport and to compare these with values used in occupational settings.

Design:

Cross-sectional, questionnaire-based study.

Settings:

Seven soccer and 11 rugby union teams.

Subjects:

140 male athletes and 108 male and 100 female spectators associated with soccer and rugby union teams.

Main outcomes:

Views on acceptable frequencies with which athletes sustain acute injuries of various levels of severity.

Results:

The responses of athletes and spectators were similar, although spectators consistently indicated a higher acceptable frequency of injury than athletes. There were no significant differences in responses as a function of respondents’ gender and age. The results confirmed an inverse relationship between the acceptable frequency of occurrence and the severity of injury, although the relationships identified by the risk-averse and risk-taking minorities within the sample population were widely different.

Conclusion:

The mean frequency–severity risk relationship identified by athletes and spectators in soccer and rugby was similar to the relationship routinely used for risk assessments in industry and commerce.
Free nicotine content and strategic marketing of moist snuff tobacco products in the United States: 2000–2006
Authors: Alpert H R , Koh H , Connolly G N
Published: August 2008

Background:

From 2000 to 2006, moist snuff sales have increased and now account for 71% of the smokeless tobacco market. Previous research has shown that major manufacturers of smokeless tobacco products manipulated free nicotine, the form most readily absorbed, to promote tolerance and addiction.

Aim:

This study examines the possibility that company-specific and brand-specific strategies of the major moist snuff manufacturers involve controlling free nicotine content and ease of dosing with products that are designed and targeted to specific groups. This study looks at the current total US moist snuff market with product design data from the Massachusetts Department of Public Health; moist snuff use from the National Survey on Drug Use and Health; market data from ACNielsen; and magazine advertising expenditures from TNS Media Intelligence.

Results:

(1) The levels of free nicotine of moist snuff products have increased over time for several major manufacturers; (2) the number and variety of sub-brands have increased over time; (3) changes in design, as reflected by variation in free nicotine associated with pH or tobacco leaf, or both, have enhanced the ease and uniformity of dosing; (4) marketing through price and advertising has increased; and (5) youth use has increased.

Conclusion:

A combination of factors including brand proliferation, control of free nicotine and product design has most likely resulted in the expanded consumption of moist snuff, particularly among young people.
How much do mental disorders contribute to New Zealand’s tobacco epidemic?
Authors: Tobias M , Templeton R , Collings S
Published: August 2008

Objective:

To quantify the share of tobacco consumed by people with 12-month mental disorders in New Zealand.

Methods:

Estimates of current smoking prevalence and the 12-month prevalence of three groups of mental disorders—anxiety, mood and substance use disorders—were derived from the New Zealand Mental Health Survey, a nationally representative survey of almost 13 000 adults (16+ years) fielded in 2003–4. Estimates of the smoking intensity ratio (comparing smokers with mental disorders to those without mental disorders) were derived from the 2006–7 New Zealand Health Survey.

Results:

Approximately 33% of all cigarettes are consumed by people with 12-month mental disorders (males 27%, females 39%), using an estimated smoking intensity ratio of 1.21. Among this group, anxiety disorders account for almost one-half of consumption, mood disorders for over one-quarter and substance use disorders for about one-fifth.

Conclusion:

This study quantifies for the first time the contribution of mental disorders to tobacco consumption in New Zealand. In particular, it identifies anxiety disorders as an important risk factor for tobacco use. People with mental disorders are an important target group for tobacco control. Enhanced collaboration and sharing of expertise between smoking cessation service providers and community mental health services are urgently needed.
Experimental policies for rebuilding depleted stocks
Authors: Martell Steven J.D. , Walters Carl J.
Published: August 2008

Experimental policies for rebuilding stocks through reduction in fishing mortality rate can be classified by severity of the reduction and duration of application of the reduced rate before moving to a long-term fishing rate goal. For stocks ranging from highly productive shrimp (Penaeidae) in the Gulf of Mexico to longer-lived, less productive Atlantic yellowfin ( Thunnus albacares ) tuna, we show that highest expected long-term fishery values are likely to come from relatively harsh experiments (F reduced to lowest value likely to be optimum for the long term) for which there is a commitment to maintain the experimental fishing mortality rate for several generations. Shorter experiments and less severe reductions in fishing rate lead to high probabilities of poor choices for postexperimental fishing rate, while much longer experiments do not produce substantially more information yet forego opportunities for higher harvests.
Have atmospheric emissions from the Athabasca Oil Sands impacted lakes in northeastern Alberta, Canada?
Authors: Hazewinkel Roderick R.O. , Wolfe Alexander P. , Pla Sergi , Curtis Chris , Hadley Kris
Published: August 2008

The rate of bitumen extraction in northeastern Alberta, Canada, is outpacing the state of ecological understanding of the region, so that the extent of potential disturbances caused by atmospheric deposition remains largely unknown. Atmospheric SO2 emissions from the Fort McMurray region of Alberta (∼300 t·day–1) constitute ∼5% of the Canadian total. Combined with an estimated NOx production of ∼300 t·day–1, these emissions have the potential to acidify surface waters. Diatom assemblages in dated sediment cores from eight acid-sensitive lakes were analyzed to assess the effects of acidifying emissions on boreal lake ecosystems. There is no evidence that these lakes have become acidified. Instead, many of the lakes show characteristic changes towards greater productivity and occasionally greater alkalinity. The absence of evidence for acidification does not imply that emissions from the Oil Sands are environmentally benign, but rather suggests that the biogeochemistry of these lakes differs fundamentally from well-studied acidified counterparts in northern Europe and eastern North America. Complex interactions involving in-lake alkalinity production, internal nutrient loading, and climate change appear to be driving these lakes towards the new ecological states reported.
River flow controls ecological processes and invertebrate assemblages in subsurface flowpaths of an ephemeral river reach
Authors: Datry Thibault , Larned Scott T.
Published: August 2008

We present the first measurements of solutes, invertebrates, and microbial activity in the semi-perched hyporheic, parafluvial, and riparian flowpaths of an ephemeral river channel. Dissolved organic carbon (DOC), nitrogen (DON), and phosphorus (DOP) concentrations decreased as water from an adjacent river mainstem moved through the flowpaths. DOC, DON, and DOP processing rates decreased with increasing mainstem flow and increased with parafluvial zone length. These patterns suggest that the surface water zones of perched river systems are organic nutrient sources to subsurface flowpaths and that parafluvial zones of these systems are strong sinks for organic matter. No longitudinal changes were detected in NO3–concentrations, and relationships between NO3–processing and hydrological variables were not significant. NO3–concentrations were uniformly high, and microbial activity and DOC and dissolved reactive phosphorus (DRP) concentrations were low, suggesting that biological NO3–removal was carbon- or phosphorus-limited. Invertebrate assemblages also varied between subsurface zones: density and taxon richness in the hyporheic and parafluvial zones were higher than in the riparian zone, and evenness was higher in the riparian zone than in the hyporheic or parafluvial zones. Distinct invertebrate assemblages in riparian zones may reflect greater hydrologic stability compared with hyporheic and parafluvial zones.
Forage fish of the Pacific Rim as revealed by diet of a piscivorous seabird: synchrony and relationships with sea surface temperature
Authors: Thayer Julie A. , Bertram Douglas F. , Hatch Scott A. , Hipfner Mark J. , Slater Leslie , Sydeman William J. , Watanuki Yutaka
Published: August 2008

We tested the hypothesis of synchronous interannual changes in forage fish dynamics around the North Pacific Rim. To do this, we sampled forage fish communities using a seabird predator, the rhinoceros auklet ( Cerorhinca monocerata ), at six coastal study sites from Japan to California. We investigated whether take of forage fishes was related to local marine conditions as indexed by sea surface temperature (SST). SST was concordant across sites in the eastern Pacific, but inversely correlated between east and west. Forage fish communities consisted of anchovy ( Engraulis spp.), sandlance ( Ammodytes spp.), capelin ( Mallotus spp.), and juvenile rockfish ( Sebastes spp.), among others, and take of forage fish varied in response to interannual and possibly lower-frequency oceanographic variability. Take of primary forage species were significantly related to changes in SST only at the eastern sites. We found synchrony in interannual variation of primary forage fishes across several regions in the eastern Pacific, but no significant east–west correlations. Specifically in the Japan Sea, factors other than local SST or interannual variability may more strongly influence forage fishes. Predator diet sampling offers a fishery-independent, large-scale perspective on forage fish dynamics that may be difficult to obtain using conventional means of study.
Combining turbine blade-strike and life cycle models to assess mitigation strategies for fish passing dams
Authors: Ferguson John W. , Ploskey Gene R. , Leonardsson Kjell , Zabel Richard W. , Lundqvist Hans
Published: August 2008

The combined model produced a tool for evaluating effects on fish populations from passage through hydropower turbines at dams. Mean blade-strike mortality was higher for adult Atlantic salmon ( Salmo salar ) and sea-run brown trout ( Salmo trutta ) (25.2%–45.3%) than for juveniles (5.3%–9.7%). Based on life cycle modeling, salmon populations in two Swedish rivers responded differently to strategies for mitigating mortality caused by fish striking turbine blades. Although population growth rates increased up to 3% and were relatively similar for both rivers, the relative increase in the number of female salmon escaping above a dam annually after 20 years when both juveniles and adults were protected was greater in the River Piteälven (68%) than in the River Vindelälven (46%) and was approximately four times greater in the River Piteälven (38% vs. 10%) when only adults were protected. These population responses were not predicted by estimates of mortality through turbines. They showed the model could be used to evaluate strategies to conserve fish populations affected by dams located in fish migratory corridors and how postspawn adults contributed to population productivity.
Modeling cadmium accumulation in indigenous yellow perch (Perca flavescens)
Authors: Kraemer Lisa D. , Campbell Peter G.C. , Hare Landis
Published: August 2008

We used field data from transplantation and caging studies with juvenile yellow perch ( Perca flavescens ) to test a kinetic bioaccumulation model for cadmium (Cd). The model, which considers both dietary and aqueous sources of Cd, was first used to predict the dynamics of Cd accumulation in perch exposed to high ambient Cd for 70 days. Model simulations for hepatic Cd agreed well with the observed time course of Cd accumulation in the liver, but for the gills and gut, the predicted accumulations after 70 days were about three times higher than the observed values, suggesting that these latter organs can alter their ability to take up and (or) eliminate Cd. The model was also used to predict steady-state Cd concentrations in the gills, gut, and liver of perch living in lakes along a Cd gradient. Agreement between predicted and observed steady-state Cd concentrations was reasonable in lakes with low to moderate Cd concentrations, but in lakes with high dissolved Cd (>1.5 nmol·L–1), the model overestimated Cd accumulation, particularly in the gills and gut. These results suggest that kinetic bioaccumulation models may better apply to some organs than to others. Because metal-induced toxicity is normally organ-specific, their application in a risk assessment context should be undertaken with caution.
Effects of marine-derived nutrients on population dynamics of sockeye salmon (Oncorhynchus nerka)
Authors: Uchiyama Tadayasu , Finney Bruce P. , Adkison Milo D.
Published: August 2008

The effects of marine-derived nutrients (MDN) on the productivity of sockeye salmon ( Oncorhynchus nerka ) stocks in Alaska, USA, were examined through nitrogen stable isotope analysis of smolts and mathematical models of the sockeye stock–recruit relationship. Smolt δ15N was used to infer the degree to which smolts depend on MDN for their growth. We found that characteristics of sockeye nursery lakes and watersheds significantly affected the availability of MDN to juvenile sockeye. The magnitude of escapement and water residence time were the most important factors affecting the MDN availability to juvenile salmon. Analysis of stock–recruit models indicated that regional environmental fluctuations had a large effect on stock productivities. However, stock–recruitment data showed little evidence that increasing MDN input to nursery lakes increased stock productivities. Stock–recruitment data may be poorly suited to detection of the influence of MDN because of the multitude of factors that influence juvenile survival in the first several years of their life.
No indications of Atlantic salmon (Salmo salar) shoaling with kin in the Baltic Sea
Authors: Palm Stefan , Dannewitz Johan , Järvi Torbjörn , Koljonen Marja-Liisa , Prestegaard Tore , Olsén K. Håkan
Published: August 2008

Several studies have shown that fish shoals may consist of closely related individuals. It has been found, for example, that released out-migrating salmon smolts tend to aggregate with kin, including when sibling groups have been reared separately. We used genetic microsatellite markers to test whether “shoals” of adult Atlantic salmon ( Salmo salar ) during the marine phase (i.e., aggregations of fish caught in drift nets at offshore feeding areas in the Baltic Sea) consisted of closely related individuals (full-siblings, half-siblings). We found no evidence of kin cohesiveness related to shoals, however. Despite a weak overall tendency for individuals assigned to the same population (river or stock) to occur together, estimates of genetic relatedness in combination with consistent heterozygote deficiencies, and results from mixed-stock analyses and assignment tests collectively indicated that shoals consisted of unrelated fish from multiple populations.
Copepod production drives recruitment in a marine fish
Authors: Castonguay Martin , Plourde Stéphane , Robert Dominique , Runge Jeffrey A. , Fortier Louis
Published: August 2008

Predicting fluctuations in recruitment of commercial marine fish remains the Holy Grail of fisheries science. In previous studies, we identified statistical relationships linking Atlantic mackerel ( Scomber scombrus ) recruitment to regional climate, zooplankton biomass, and the production of copepod nauplii over a decade (1982–1991) that included the exceptionally strong year class of 1982. Here we tested the validity of these relationships by adding a second decade (1992–2003) of observations that includes another exceptional year class in 1999. We provide the first field-based evidence linking availability of plankton prey in the sea to early growth of larval fish and to year-class strength in a commercially exploited marine fish. Recruitment is shown to strongly depend on production of the copepod nauplii species that contribute to the diet of mackerel larvae. Both strong year classes were characterized by exceptionally high availability of these specific prey. We suggest that mackerel recruitment can be anticipated 3 years in advance based on prey availability during the first weeks of planktonic life and predict a strong year class for fish hatched in 2006.
A validated description of age and growth of western Atlantic bluefin tuna (Thunnus thynnus)
Authors: Neilson John D. , Campana Steven E.
Published: August 2008

Current stock assessments of western Atlantic bluefin tuna ( Thunnus thynnus ) use age-structured population analyses, but the age assignment in the population model is made using an age–length relationship derived from mark and recapture studies largely completed during the 1970s. In our study, the deposition of bomb radiocarbon was used as a dated mark to validate age inferences of bluefin tuna and to compare the validated ages with those predicted from the age–length relationship. The results support the view that the age–length relationship currently in use for the assessment overestimates growth rate and the ultimate size of the fish. These findings have implications for the estimation of stock productivity and may negatively impact the rebuilding schedules established by fisheries managers.
Discrete element method (DEM) numerical modeling of double-twisted hexagonal mesh
Authors: Bertrand David , Nicot François , Gotteland Philippe , Lambert Stéphane
Published: August 2008

Double-twisted hexagonal mesh is used in several fields of civil engineering (gabion structures, retaining nets against rockfalls, etc.). This paper presents an approach based on the discrete element method (DEM) to model this specific mechanical system. Constitutive modeling in finite strains is proposed to take into account the elastoplastic behavior with hardening of the metallic wire mesh. Model parameters are calibrated from a macroscopic point of view by comparing simulations to experimental tensile strength tests performed at the wire-mesh sheet scale. Additional experimental tests, with different mesh sizes and wire diameters, are conducted, yielding valuable data to validate this numerical approach. Lastly, the modeling capabilities are investigated. The simulation of a rockfall-protection structure subjected to an impact loading is presented and the results are discussed from an engineering point of view.
A modified approach for determination of nonlinear properties in seismic response analyses for 200 m high core rock-fill dams
Authors: Li Hongjun , Chi Shichun , Lin Gao , Zhong Hong
Published: August 2008

Equivalent linear analyses are widely used for estimation of site response and safety status of rock-fill dams subjected to strong earthquakes. However, the average normalized curves incorporated in the equivalent-linear iterative process cannot precisely depict the variations of dynamic parameters with shearing strain for one type of soil material under a wide range of confining pressures. Thus, a modified approach for the determination of nonlinear properties for soil elements confined under a broad range of effective pressures in site response analyses for high rock-fill dams (>200 m) is proposed. In this approach, the normalized confining-pressure-interpolating curves (CPI curves) of each soil element under different effective stress are obtained by linearly interpolating or extrapolating by its in situ stress. By comparing the results obtained by equivalent linear analyses incorporating the average curves and the CPI curves, respectively, the impact of utilizing the recommended curves when determining nonlinear soil properties on site response analyses of high rock-fill dams (>200 m) is discussed. It is shown that the refinement in the determination of nonlinear properties during site response can be utilized in the near future by incorporating the results of this study in practice.
Clogging of unsaturated gravel permeated with landfill leachate
Authors: McIsaac Reagan , Rowe R. Kerry
Published: August 2008

The results of an experimental investigation into the clogging of unsaturated, uniformly graded 50 mm gravel permeated with municipal solid waste landfill leachate are reported. The flow of leachate within the unsaturated gravel was heterogeneous and occurred in free-draining flow pathways. The leachate experienced reductions in the concentrations of both the organic and inorganic constituents after passing through the unsaturated gravel although there was very little clogging within the unsaturated gravel. The average drainable porosity was reduced by 8% after 8 years permeation. The biofilm was limited to areas on the gravel where leachate could be retained; predominantly on top of lateral gravel surfaces and near particle-to-particle contacts. As a result, only a small fraction of the total surface area of the unsaturated gravel was covered with biofilm. The short leachate retention time and the sporadic distribution of biofilm limited the degree of contact between the bacteria and the leachate and hence limited biologically induced clogging within the unsaturated gravel. The data suggest that leachate collection systems should be designed and operated such that the drainage material of the leachate collection system remains unsaturated for as long as possible.
Simplified models of spreading flow of dry granular material
Authors: Hungr Oldrich
Published: August 2008

Shallow-flow integrated numerical models of landslide and avalanche motion have recently experienced rapid development. An important aspect of model development is verification, to show that models are correct and reasonably robust in their application of basic physical principles. Most existing models have been verified against controlled laboratory experiments using dry granular material. In this article, it is shown that spreading flows such as the “dam-break” problem in frictional material pose problems for shallow-flow analysis. A series of dam-break laboratory experiments have been carried out with several different slope angles and bed materials. A model was then applied using four alternative assumptions regarding the distribution of earth pressure in the sliding mass. It was shown that assumptions commonly used in previous work produce very substantial errors (up to 200%) when applied to the prediction of dam-break runout in material with both internal and basal friction. A new model is proposed based on a simple modification of the well-known SH assumptions. This new model provides excellent agreement with experimental results, both for shallow avalanches and spreading flows. It represents a means to greatly expand the applicability of shallow-flow models to real landslide problems involving spreading flow, such as flow slides.
THE TRACE FUNCTION AND COMPLEX KLEINIAN GROUPS IN $P_{\mathbb{C}}^{2}$
Authors: NAVARRETE JUAN-PABLO
Published: August 2008

It is well known that the elements of PSL(2, ℂ) are classified as elliptic, parabolic or loxodromic according to the dynamics and their fixed points; these three types are also distinguished by their trace. If we now look at the elements in PU(2,1), then there are the equivalent notions of elliptic, parabolic or loxodromic elements; Goldman classified these transformations by their trace. In this work we extend the classification of elements of PU(2,1) to all of PSL(3, ℂ); we also extend to this setting the theorem that classifies them according to their trace. We use the notion of limit set introduced by Kulkarni, and calculate the limit set of every cyclic subgroup of PSL(3, ℂ) acting on [Formula: see text]. Given a classical Kleinian group it is possible to "suspend" this group to a subgroup of PSL(3, ℂ); we also calculate the limit set of this suspended group.
DERIVED SCHWARZ MAP OF THE HYPERGEOMETRIC DIFFERENTIAL EQUATION AND A PARALLEL FAMILY OF FLAT FRONTS
Authors: SASAKI TAKESHI , YAMADA KOTARO , YOSHIDA MASAAKI
Published: August 2008

In one of the previous papers, we defined a map, called the hyperbolic Schwarz map, from the one-dimensional projective space to the three-dimensional hyperbolic space by use of solutions of the hypergeometric differential equation, and thus obtained closed flat surfaces belonging to the class of flat fronts. We continue the study of such flat fronts in this paper. First, we introduce derived Schwarz maps of the hypergeometric differential equation and, second, we construct a parallel family of flat fronts connecting the classical Schwarz map and the derived Schwarz map.
COSMIC RAYS PROPAGATION IN AXIONIC DARK MATTER
Authors: SAHU SARIRA
Published: August 2008

Axions are the possible candidates for the non-baryonic dark matter in the Universe. Numerical calculation suggest that, these axions clumped together to form denser objects like miniclusters and axion boson stars. We have calculated the damping of cosmic rays mainly electrons propagating in the dark halo of our own galaxy, which suppose to contains the axionic dark matter as miniclusters. Our calculation shows that almost all the high energy cosmic rays will penetrate through these objects without losing energy.
DETECTING EXTRA DIMENSION BY HELIUM-LIKE IONS
Authors: LIU YU-XIAO , ZHANG XIN-HUI , DUAN YI-SHI
Published: August 2008

Considering that gravitational force might deviate from Newton's inverse-square law and become much stronger in small scale, we present a method to detect the possible existence of extra dimensions in the ADD model. By making use of an effective variational wave function, we obtain the nonrelativistic ground energy of a helium atom and its isoelectronic sequence. Based on these results, we calculate gravity correction of the ADD model. Our calculation may provide a rough estimation about the magnitude of the corresponding frequencies which could be measured in later experiments.
DYNAMICAL STUDY OF HEAVY-BARYON SPECTROSCOPY
Authors: YANG YOUCHANG , DENG CHENGRONG , HUANG HONGXIA , PING JIALUN
Published: August 2008

The spectroscopy of S-wave heavy-baryons containing one, two or three heavy quarks is investigated in a constituent quark model. We solve the Schrödinger equation for three particles exactly by means of a Gaussian expansion method. The calculated results of heavy-baryon spectra with a single heavy quark are consistent with the experimental data.
ENTANGLEMENT MODULATION IN A SPIN CHAIN BY A LOCAL IMPURITY
Authors: APOLLARO TONY J. G. , CUCCOLI ALESSANDRO , FUBINI ANDREA , PLASTINA FRANCESCO , VERRUCCHI PAOLA
Published: August 2008

We study the ground-state entanglement properties of an XX spin 1/2 chain in transverse field, in its quasi-long-ranged ordered phase, with a magnetic impurity, represented in terms of an additional transverse magnetic field located at one precise site. For such a system, we show that a control of the ground state entanglement can be achieved by acting on the impurity field. To demonstrate this possibility, we evaluate exactly the nearest neighbor and next-nearest neighbor concurrence in the presence of the impurity. It turns out that either an enhancement or a quenching of entanglement between selected spin pairs can be obtained by acting on the intensity of the impurity. For specific values of the magnetic field a spatial modulation of concurrence along the chain is also obtained.
QUANTUM ERROR-CORRECTION FOR SPATIALLY CORRELATED ERRORS
Authors: ARIMITSU T. , HAYASHI T. , KITAJIMA S. , SHIBATA F.
Published: August 2008

It is shown that errors due to spatially correlated noises can be corrected by the quantum error-correction code and error-correction procedure prepared for those for independent noises. A model of noisy-channel which is under the influence of spatially correlated quantum Brownian motion is investigated within the framework of non-equilibrium thermo field dynamics that is a canonical operator formalism for dissipative quantum systems.
QUANTUM TRAJECTORIES, FEEDBACK AND SQUEEZING
Authors: BARCHIELLI A. , GREGORATTI M. , LICCIARDO M.
Published: August 2008

Quantum trajectory theory is the best mathematical set up to model continual observations of a quantum system and feedback based on the observed output. Inside this framework, we study how to enhance the squeezing of the fluorescence light emitted by a two-level atom, stimulated by a coherent monochromatic laser. In the presence of a Wiseman-Milburn feedback scheme, based on the homodyne detection of a fraction of the emitted light, we analyze the squeezing dependence on the various control parameters.
ALGEBRAIC FORMULATION OF QUANTUM ERROR CORRECTION
Authors: BÉNY CÉDRIC , KRIBS DAVID W. , PASIEKA ARON
Published: August 2008

We give a brief introduction to the algebraic formulation of error correction in quantum computing called operator algebra quantum error correction (OAQEC). Then we extend one of the basic results for subsystem codes in operator quantum error correction (OQEC) to the OAQEC setting: Every hybrid classical-quantum code is shown to be unitarily recoverable in an appropriate sense. The algebraic approach of the proof yields a new, less technical proof for the OQEC case.
A NEW APPROACH TO CHARACTERIZE QUBIT CHANNELS
Authors: CARUSO FILIPPO , GIOVANNETTI VITTORIO
Published: August 2008

We analyze qubit channels by exploiting the possibility of representing two-level quantum systems in terms of characteristic functions. To do so, we use functions of non-commuting variables (Grassmann variables), defined in terms of generalized displacement operators, following an approach which resemble the one adopted for continuous–variable (Bosonic) systems. It allows us to introduce the notion of qubit Gaussian channels and to show that they share similar properties with the corresponding continuous–variable counterpart. Some examples of qubit channels are investigated using this approach.
CIRCULANT DECOMPOSITIONS FOR BIPARTITE QUANTUM SYSTEMS
Authors: CHRUŚCIŃSKI DARIUSZ , KOSSAKOWSKI ANDRZEJ
Published: August 2008

We construct a large class of quantum d ⊗ d states which are positive under partial transposition (so called PPT states). The construction is based on certain direct sum decomposition of the total Hilbert space displaying characteristic circular structure — that is way we call them circulant states. It turns out that partial transposition maps any such decomposition into another one and hence both original density matrix and its partially transposed partner share similar cyclic properties. This class contains many well known examples of PPT states from the literature and gives rise to a huge family of completely new states.
COMPLEXITY, NOISE AND QUANTUM INFORMATION ON ATOM CHIPS
Authors: CIRONE M. A. , NEGRETTI A. , RECATI A. , CALARCO T.
Published: August 2008

The realization of quantum logic gates with neutral atoms on atom chips is investigated, including realistic features, such as noise and actual experimental setups.
QUANTUM MEASUREMENT AND CHARGE DENSITY OSCILLATIONS IN DOUBLE QUANTUM DOTS
Authors: CRUZ H. , LUIS D.
Published: August 2008

In this work, we have studied the post-measurement dynamics of several electrons in a double quantum dot system using a new method of calculation. We have solved the effective-mass non-linear Schrödinger equation for two electron wave packets in a double quantum well taking into account the different number of projected electrons in each quantum well after an observation. It is found the existence of a critical density that reduces strongly the tunneling dynamics between both quantum wells. In addition, we have shown the possibility of having a new kind of electromagnetic radiation emerging from a semiconductor device after a quantum observation.
PROTECTED COMPUTATIONAL SUBSPACES OF COUPLED SUPERCONDUCTING QUBITS
Authors: MASTELLONE A. , D'ARRIGO A. , PALADINO E. , FALCI G.
Published: August 2008

We discuss the effect of low-frequency noise on interacting superconducting qubits in a fixed coupling scheme. By properly choosing operating conditions, within the adiabatic framework the systems develops two decoupled subspaces. The subspace where a SWAP operation takes place turns out to be resilient to low frequency fluctuations. The possibility to encode a single qubit in a protected two-physical-qubit system subspace is briefly discussed.
MEMORY EFFECTS IN A MARKOV CHAIN DEPHASING CHANNEL
Authors: D'ARRIGO A. , DE LEO E. , BENENTI G. , FALCI G.
Published: August 2008

We study a dephasing channel with memory, modelled by a Markov chain. We show that even weak memory effects have a detrimental impact on the performance of quantum error correcting schemes designed for uncorrelated errors. We also discuss an alternative scheme that takes advantage of memory effects to protect quantum information.
A DEEPER INSIGHT INTO QUANTUM STATE TRANSFER FROM AN INFORMATION FLUX VIEWPOINT
Authors: DI FRANCO C. , PATERNOSTRO M. , PALMA G. M.
Published: August 2008

We use the recently introduced concept of information flux in a many-body register in order to give an alternative viewpoint on quantum state transfer in linear chains of many spins.
NON-GAUSSIAN CONTINUOUS-VARIABLE TELEPORTATION
Authors: MARIAN PAULINA , MARIAN TUDOR A.
Published: August 2008

We have recently shown that the output field in the Braunstein–Kimble protocol of teleportation is a superposition of two fields: the input one and a field created by Alice's measurement and by displacement of the state at Bob's station by using the classical information provided by Alice. We study here the noise added by teleportation and compare its influence in the Gaussian and non-Gaussian settings.
ENTANGLEMENT DYNAMICS IN QUANTUM SPIN CHAINS
Authors: MICHALSKI MŁOSZ
Published: August 2008

We study patterns of temporal evolution, creation and transport, of entanglement in quantum spin chains. The model used is an isotropic Heisenberg chain with periodic boundary conditions, and we obtain in analytic form the time dependence of concurrence and negativity of various pairs of spins in the system. The objective of the present study is to assess the usefulness of various averaged entanglement measures in the characterization of entangling properties of quantum evolutions.
SEMANTICS OF QUANTUM PROGRAMMING LANGUAGE LANQ
Authors: MLNAŘÍK HYNEK
Published: August 2008

We show a memory model of an imperative concurrent quantum programming language LanQ. The memory model is used to specify the shape of semantical structure upon which the language operational semantics is defined. We also outline the language abilities in the area of formal verification on an example implementation of teleportation protocol.