bluuebunny/crossref_metadata_2025 huggingface dataset:
Multiple pathways mediate the effects of climate change on maternal reproductive traits in a red deer population
Authors: Stopher Katie V. , Bento Ana I. , Clutton-Brock Tim H. , Pemberton Josephine M. , Kruuk Loeske E. B.
Published: November 2014

Temporal changes in phenological traits arising as a consequence of recent rapid environmental change have been widely demonstrated in animal populations. Increasingly, studies are seeking to understand the impact of changes in such traits on individual fitness and population dynamics, with the ultimate aim of predicting population persistence or extinction under different climate scenarios. Here, we examined the effects of environmental change on maternal reproductive traits in a wild population of red deer (Cervus elaphus) and sought to explain why, despite a rapid advance in offspring birth dates, we observed no apparent consequences for offspring fitness. By using path analysis, we identified both direct and indirect paths along which changes in environmental conditions affected birth date, birth mass, juvenile survival, and female fecundity. In general, warmer temperatures were associated with earlier birth dates and greater birth mass, and higher rainfall was associated with reduced juvenile survival and reduced female fecundity. We also examined concurrent effects of population density, maternal age, and reproductive history, and found that temporal stasis in average trait values, at least in part, could be explained by antagonistic roles of direct and indirect effects of changing climate and increasing population density. Identification of the many mechanisms that contribute to the dynamics of phenotypic traits is challenging; this study demonstrates the need to consider both climatic and demographic variation in order to understand the fitness consequences of changes in phenological traits.
Food resources and intestinal parasites as limiting factors for boreal vole populations during winter
Authors: Forbes Kristian M. , Stuart Peter , Mappes Tapio , Henttonen Heikki , Huitu Otso
Published: November 2014

Processes limiting the growth of cyclic vole populations have stimulated considerable research and debate over several decades. In Fennoscandia, the peak density of cyclic vole populations occurs in fall, and is followed by a severe winter decline. Food availability and intestinal parasites have been demonstrated to independently and synergistically limit wildlife populations. The purpose of this study was to directly compare competing food and parasite hypotheses on the limitation of overwintering high‐density vole populations. Moreover, we evaluated the ability of food limitation and nematode infection to interact and thereby intensify population declines. A two‐factor experiment with food supplementation and antihelminthic medication was conducted on replicated, enclosed field vole (Microtus agrestis) populations in central Finland over one full boreal winter. Population abundance, survival, and demographic attributes were monitored through live trapping. Vole feces were concurrently examined for the eggs of Heligmosomidae nemadotes and oocysts of eimerian coccidians. We found that vole density declined in all treatment groups throughout winter. However, food supplementation mitigated this decline through positive effects on reproduction, and voles in food‐supplemented populations were generally in better physiological condition than non‐supplemented voles. Food supplementation and antihelminthic treatment reduced the prevalence of Heligmosomidae nematodes, while neither food nor medication affected the prevalence of eimerians, or infection intensity of either parasite group. Although food supplementation and antihelminthic medication aided in the clearance of Heligmosomidae nematodes, their prevalence did not influence vole population growth, and this parasite group is therefore unlikely to contribute to the cyclic winter decline of boreal vole populations. Instead food resources acting alone were the primary factor limiting vole population growth.
Effect of side-stream phosphorus recovery on biological phosphorus removal performance investigated by chemical and microbial analyses in a novel BNR-IC process
Authors: Zou H. M. , Lu X. W. , Li T.
Published: November 2014

The aim of this study was to assess the effect of side-stream ratio (SSR) on performance of phosphorus (P) removal and recovery in a novel process linking biological nutrients removal (BNR) and induced crystallization (IC). Results showed that P removal efficiency was significantly enhanced when given an appropriate SSR, resulting in effluent P concentrations decreasing from 0.75 to 0.39 mg/L with an increase of SSR from 0 to 35%, where a maximum of 7.19 mg/L P recovery amount was obtained at 35% of SSR. Increasing the SSR can favor the P recovery, while an excessively high SSR (more than 35%) would have a negative effect on the subsequent biological P removal in the BNR-IC system. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis showed that in total, 11 DGGE bands of highest species richness were visually detected and significant changes in microbial community structure were found, with SSR variations ranging from 0 to 55%. Moreover, an increase in SSR can cause an increase in microbial community biodiversity; where microbial populations correspond to the 11 bands, they were generally classified into five different phyla or classes (Beta-, Gamma-, and Deltaproteobacteria, as well as Clostridia and Flavobacteria) based on the evolutionary tree analysis.
Reuse of constructed wetland effluents for irrigation of energy crops
Authors: Barbagallo S. , Barbera A. C. , Cirelli G. L. , Milani M. , Toscano A.
Published: November 2014

The aim of this study was to evaluate biomass production of promising ‘no-food’ energy crops, Vetiveria zizanoides (L.) Nash, Miscanthus × giganteus Greef et Deu. and Arundo donax (L.), irrigated with low quality water at different evapotranspiration restitutions. Two horizontal subsurface flow (H-SSF) constructed wetland (CW) beds, with different operation life (12 and 6 years), were used to treat secondary municipal wastewaters for crop irrigation. Water chemical, physical and microbiological parameters as well as plant bio-agronomic characters were evaluated. The results confirm the high reliability of CWs for tertiary wastewater treatment given that the H-SSF1 treatment capacity remained largely unchanged after 12 years of operation. Average total suspended solids, chemical oxygen demand and total nitrogen removal for CWs were about 68, 58 and 71%, respectively. The Escherichia coli removal was satisfactory, about 3.3 log unit for both CW beds on average, but caution should be taken as this parameter did not achieve the restrictive Italian law limits for wastewater reuse. The average above-ground dry matter productions were 7 t ha−1 for Vetiveria zizanoides, 24 t ha−1 for Miscanthus × giganteus and 50 t ha−1 for Arundo donax. These results highlight attractive biomass yield by using treated wastewater for irrigation with a complete restitution of evapotranspiration losses.
Comparison of continuous versus pulsed ultraviolet light emitting diode use for the inactivation of Bacillus globigii spores
Authors: Tran Tho , Racz LeeAnn , Grimaila Michael R. , Miller Michael , Harper Willie F.
Published: November 2014

Light emitting diodes (LEDs) in the ultraviolet (UV) range offer a promising alternative for the disinfection of water. LEDs have many advantages over conventional UV lamps but there are concerns related to the operating life of the LED lamps. In this project Bacillus globigii was inactivated using UV LED technology. The experimental strategy included using pulsed ultraviolet (PUV) output rather than continuous UV (CUV) current in order to reduce the power requirements and extend the life of the lamps. The kinetic profiles for CUV experiments reached 6-log inactivation faster than PUV at 9.1% duty cycle (approx. 840 vs. 5,000 s) but the PUV required lower fluence (365 vs. 665 J/m2). In addition, the inactivation rate constants associated with PUV were generally higher than those of CUV (4.6–5.1 vs. 3.6–4.4 m2/J), which supports the notion that high energy bursts are more effective at causing cellular damage. Multi-target kinetics applied to most of the kinetic observations and tailing effects were generally observed. PUV LED appears to have potential to extend the lifetime of the LEDs for inactivation of spore-forming pathogens.
Forecasting performance of support vector machine for the Poyang Lake's water level
Authors: Lan Yingying
Published: November 2014

The growth of forecasting models has resulted in the development of an excellent model known as the support vector machine (SVM). SVMs can find a global optimal solution equipped with kernel functions. This research trains and tests the SVM network and constructs the support vector regression prediction model by using hydrologic data. Six hydrologic time series were calculated by different kernel functions (namely, linear, polynomial, radial basis function (RBF)), to determine which kernel is the more suitable hydrologic time series in practice. A new solution is presented to identify the good parameter (C; g) by using grid-search and cross-validation. Results prove that linear SVM is a superior model to polynomial and RBF and produced the most accurate results for modeling hydrologic time series behavior as complex hydrologic phenomena. The case study also shows that the calculation errors were correlated with data characteristics. More stable raw data will result in a more accurate result, whereas more random data will result in a more inaccurate result. Model performance could also be dependent on base data nonlinearity.
Extracellular polymeric substances and dewaterability of waste activated sludge during anaerobic digestion
Authors: Ye Fenxia , Liu Xinwen , Li Ying
Published: November 2014

Anaerobic digestion of waste activated sludge was conducted to gain insight into the mechanisms underlying change in sludge dewaterability during its anaerobic digestion. Unexpectedly, the results indicated that sludge dewatering properties measured by capillary suction time only deteriorated after 10 days of anaerobic digestion, after which dewaterability recovered and remained stable. The loosely bound extracellular polymeric substance (LB-EPS) content increased three-fold after 20 days of anaerobic digestion, and did not change significantly during the remaining 30 days. The tightly bound EPS (TB-EPS) content reduced slightly after 20 days of anaerobic digestion, and stabilized during the last 30 days. Polysaccharides (PS) and proteins (PN) content in LB-EPS increased after 10 days of anaerobic digestion. However, PS and PN contents in TB-EPS decreased slightly. The relationship analysis showed that only LB-EPS correlated with dewaterability of the sludge during anaerobic digestion.
Study on method for assessment of the physical structure integrity in Chagan lake in China based on remote sensing
Authors: Fu Bo-lin , Li Ying , Zhang Bai , Yin Bai-shu , Zhu Hong-lei , Xin Ze-feng
Published: November 2014

This paper, taking Chagan lake as the study area, uses and improves MWR V1.0 (Rivers (Lake) Health Assessment Indicators, Standards and Methods V1.0) relating to the theory and method of physical structure integrity assessment. A 500 m × 1000 m grid on the lakeshore zone is a basic evaluation unit, and then a lakeshore physical structural integrity evaluation system using remote sensing (RS) and geographic information system (GIS) technology is established, which contains a target layer, criterion layer and indicator layer. The criterion layer consists of lakeshore condition, shoreline development rate and lake atrophy rate, and the index layer is composed of slope, vegetation cover rate and water level change rate, and another eight indicators. The results showed that for the 23 monitoring points in Chagan lake and the 15 monitoring points in Xinmiao lake, the evaluation results based on RS were 0.60–0.74 and 0.35–0.52, respectively, and the field evaluation results were 0.64–0.77 and 0.35–0.55, respectively. The evaluation results of the two methods consistently indicated that the physical structure of the lakeshore of Chagan lake was healthy and the Xinmiao's lakeshore was sub-health. On this basis, a piecewise evaluation method of physical structure integrity based on the division of the nature reserve function was proposed in this paper.
Optimization of operation conditions for preventing sludge bulking and enhancing the stability of aerobic granular sludge in sequencing batch reactors
Authors: Zhou Jun , Wang Hongyu , Yang Kai , Ma Fang , Lv Bin
Published: November 2014

Sludge bulking caused by loss of stability is a major problem in aerobic granular sludge systems. This study investigated the feasibility of preventing sludge bulking and enhancing the stability of aerobic granular sludge in a sequencing batch reactor by optimizing operation conditions. Five operation parameters have been studied with the aim to understand their impact on sludge bulking. Increasing dissolved oxygen (DO) by raising aeration rates contributed to granule stability due to the competition advantage of non-filamentous bacteria and permeation of oxygen at high DO concentration. The ratio of polysaccharides to proteins was observed to increase as the hydraulic shear force increased. When provided with high/low organic loading rate (OLR) alternately, large and fluffy granules disintegrated, while denser round-shape granules formed. An increase of biomass concentration followed a decrease at the beginning, and stability of granules was improved. This indicated that aerobic granular sludge had the resistance of OLR. Synthetic wastewater combined highly and slowly biodegradable substrates, creating a high gradient, which inhibited the growth of filamentous bacteria and prevented granular sludge bulking. A lower chemical oxygen demand/N favored the hydrophobicity of granular sludge, which promoted with granule stability because of the lower diffusion rate of ammonia. The influence of temperature indicated a relatively low temperature was more suitable.
An Interface Model Including Cracks and Roughness Applied to Masonry
Authors: Fouchal Fazia , Lebonb Frédéric , L. Raffa Maria , Vairo Giuseppe
Published: November 2014

In this paper an interface model accounting for roughness and micro-cracks is presented and applied to
masonry-like structures. The model is consistently derived by coupling a homogenization approach and arguments of
asymptotic analyses. A numerical procedure is introduced and numerical results, based on a finite element formulation,
are successfully compared with experimental data , obtained on masonry samples undergoing to shear tests. Finally, a
parametric numerical analysis is proposed, highlighting the influence of the roughness features on the interface response.
Computational Methods for Masonry Vaults: A Review of Recent Results
Authors: Tralli A. , Alessandri C. , Milani G.
Published: November 2014

The present paper makes a critical review of some methods and models, now available in the technical litera-ture and commonly used in the analysis of masonry vaults up to their collapse, by highlighting advantages and drawbacks of each approach. All methods adopted to describe the mechanical behavior of masonry structures, in order to be reliable, must take into account the distinctive aspects of masonry, namely the scarce (or zero) tensile strength, the good resistance in compression and the occurrence of failure mechanisms through rotation-translation of rigid macro-blocks. Classic no-tension material models disregard the small existing tensile strength and make the assumption of (1) infinitely elastic be-havior in compression and (2) isotropy, giving thus the possibility to deal with either semi-analytical approaches (espe-cially for arches) or robust numerical procedures. More advanced but rather complex models are nowadays able to deal al-so with anisotropy induced by texture, small tensile strength and softening in tension, as well as by finite strength in com-pression. Traditionally – and nowadays it is still an opinion commonly accepted, in contrast with step by step complex procedures, Limit Analysis has proved to be the most effective Method for a fast and reliable evaluation of the load bear-ing capacity of vaulted masonry structures: classic lower and upper bound theorems recall respectively the concepts of equilibrium and occurrence of failure mechanisms with rigid elements. The so-called Thrust Network Method moves its steps from lower bound theorems, whereas FE limit analysis approaches with infinitely resistant elements and dissipation on interfaces take inspiration from the upper bound point of view. An alternative to Limit Analysis is represented by tradi-tional FEM combined with either elastic-plastic or damaging models with softening, commonly used for other materials but recently adapted also to masonry. They are able to provide a large set of output numerical information but further studies are still needed to ensure their proper application.
Tumor Encasement of the Right Coronary Artery: Role of Anatomic and Functional Imaging in Diagnosis and Therapeutic Management
Authors: Juan Yu-Hsiang , Chatzizisis Yiannis S , Saboo Sachin S , Rocha Tatiana , Steigner Michael L
Published: November 2014

We presented two rare cases of mediastinal tumor encasing the right coronary artery (RCA), one with recurrent metastatic thymoma and another with primary poorly differentiated neoplasm. Different degrees and locations of RCA involvement were noted. The treatment approach varied from conservative to surgical. Coronary artery involvement by mediastinal tumors is important to be investigated with imaging as it may guide the surgical planning.
“Strong Men Don't Cry, but I'm Not Strong Anymore”: A Case Study of Bodily Engagement with Stories of Loss and Grief in Palliative Care
Authors: Mundle Robert
Published: November 2014

This case study addresses the importance of “life review” with regard to the crucial and demanding emotional work of older adults in palliative care who are experiencing the existential pain of grief and loneliness near the end of life. Drawing upon the reflexive field notes of one Spiritual Health Practitioner this case study describes the spiritual needs and care for an older deafened and emotionally-inhibited man in a long-term palliative care unit who described himself by saying “all I am is stories.” By illuminating the concept of “embodied listening” in response to stories told by a patient with significant hearing loss this case study differentiates the uses of voice and of body in therapeutic relationships.
Student Nurses Learning about Death, Dying, and Loss: Too Little, Too Late?
Authors: Cavaye Joyce , Watts Jacqueline H.
Published: November 2014

Concerns about the care provided to people dying from life-threatening illness have prompted a number of international reforms to improve the quality of palliative and end-of-life (EOL) care. The majority of this care is provided by nurses. They spend more time with dying patients than any other health professionals and therefore, need specific clinical skills and knowledge. Palliative and EOL care education is increasingly being positioned as a specialism, available only to a small number of registered nurses as part of continuing professional development. However, increasing numbers of patients with life-threatening illness are being treated in non-specialist settings by nurses with a generalist education. Furthermore, undergraduate nurse education has traditionally had a limited focus on palliative and EOL care, hence claims that undergraduate nursing curricula are inadequate. Drawing on an international literature, this review explores the evidence about the adequacy of undergraduate curricula in this area. It considers the extent to which palliative and EOL curriculum is included in undergraduate nurse education and draws upon evidence from students and registered nurses, who as consumers of education, report feeling unprepared to care for and communicate with, dying patients.
Teachers' Beliefs about the Possibilities and Limitations of Digital Games in Classrooms
Authors: Beavis Catherine , Rowan Leonie , Dezuanni Michael , McGillivray Christie , O'Mara Joanne , Prestridge Sarah , Stieler-Hunt Colleen , Thompson Roberta , Zagami Jason
Published: November 2014

Teachers' beliefs about what it is (or is not) possible to achieve with digital games in educational contexts will inevitably influence the decisions that they make about how, when, and for what specific purposes they will bring these games into their classrooms. They play a crucial role in both shaping and responding to the complex contextual factors which influence how games are understood and experienced in educational settings. Throughout this article the authors draw upon data collected for a large-scale, mixed-methods research project focusing on literacy, learning and teaching with digital games in Australian classrooms, to focus explicitly on the attitudes, understandings and expectations held about digital games by diverse teachers at the beginning of the project. They seek to identify the beliefs about games that motivated teachers' participation in a digital games research project while focusing, as well, on concerns that teachers express about risks or limitations of such a project. The authors' aim is to develop a detailed picture of the mindsets that teachers bring to games-based learning environments, and the relevance of these mindsets to broader debates about the relationship between games, learning and school.
Living the Orwellian Nightmare: New Media and Digital Dystopia
Authors: Diglin Greg
Published: November 2014

This article offers an academic critique of new media culture, as viewed comparatively with George Orwell's 1984. The author makes the argument that a number of plot elements of 1984 are reflected within contemporary Western societies. The assertion is made that these parallels have developed as a consequence of new media technologies. An over-arching position is taken that real-world governments have utilised new media technologies in ways that make themselves comparable to Orwell's fictional ‘Big Brother’. The author begins by describing the socio-political landscape at the time Orwell wrote the novel. The next section addresses recent examples of ways in which government agencies have used new media technologies as a surveillance tool. The author posits that the US government uses new media technology as a propaganda tool. Through use of new media, the USA attempts to limit the ability of people to reject its narratives. In the final section, the author details the ways in which new media technologies are contributing to the destruction of language and knowledge. The author's concluding argument is that the negative effects of new media technology can only be ameliorated through critical thought.
Comparative analysis of real and ideal wire-slot play in square and rectangular archwires
Authors: Lombardo Luca , Arreghini Angela , Bratti Elena , Mollica Francesco , Spedicato Giorgio , Merlin Mattia , Fortini Annalisa , Siciliani Giuseppe
Published: November 2014

Objective: 

To evaluate the degree to which the height, width, and cross-section of rectangular and square orthodontic archwires affect the play between the archwires and the bracket slot.

Materials and Methods: 

The stated measurements (height and width) of 43 archwires from six different manufacturers were compared with real values obtained using a digital gauge. The curvature (radius) of the edge bevels was also measured to calculate the play within the slot, and this measurement was compared with the ideal value.

Results: 

The real height and width of the archwires differed from those stated by the manufacturers, falling within the range −6.47% and +5.10%. The curvature of each bevel on each archwire cross-section was shown to differ, and consequently increased the real play between the archwire and slot with respect to the ideal to different degrees.

Conclusions: 

The archwire-slot play was greater than the ideal for each archwire considered, inevitably leading to a loss of information within the system.
An Automated Internet Behavioral Weight-Loss Program by Physician Referral: A Randomized Controlled Trial
Authors: Thomas J. Graham , Leahey Tricia M. , Wing Rena R.
Published: November 2014

OBJECTIVE

To evaluate 3- and 6-month weight-loss outcomes achieved when physicians refer overweight/obese patients to an automated 3-month Internet-based behavioral weight-loss intervention.

RESEARCH DESIGN AND METHODS

A total of 154 patients age 18–70 years with a BMI between 25 and 45 kg/m2 and access to a personal computer and the Internet were randomly assigned to 3 months of Internet behavioral intervention (IBI; n = 77) with 12 weekly videos teaching behavioral weight-loss skills, a platform for submitting self-monitored data, and automated feedback or an education-only Internet-delivered eating and activity control group (IDEA; n = 77). Outcome measures were weight loss after 3 months (primary outcome) and 6 months and changes in weight-control behaviors (secondary outcomes).

RESULTS

In intent-to-treat analyses with baseline weight carried forward for missing data, IBI produced significantly larger mean (SD) weight losses than IDEA at 3 months (5.5 kg [4.4] vs. 1.3 kg [2.1]) and 6 months (5.4 kg [5.6] vs. 1.3 kg [4.1]) (P < 0.001). Participants in IBI compared with IDEA were also more likely to achieve a clinically significant weight loss of 5% of initial body weight at 3 months (53.3 vs. 9.1%) and 6 months (48.1 vs. 15.6%) (P < 0.001) and reported more frequent use of weight control–related strategies.

CONCLUSIONS

Physician referral to an Internet-based behavioral weight-loss intervention produced clinically significant weight loss for over half of the patients studied. Further research is needed to determine the effectiveness of implementing this intervention more broadly within diverse health care settings.
Altered Brain Activation Patterns Under Different Working Memory Loads in Patients With Type 2 Diabetes
Authors: Chen Yaojing , Liu Zhen , Zhang Junying , Xu Kai , Zhang Sisi , Wei Dongfeng , Zhang Zhanjun
Published: November 2014

OBJECTIVE

Type 2 diabetes mellitus (T2DM) has important effects on cognition and the risk for Alzheimer disease (AD). Working memory (WM) is a susceptible cognitive domain of mild cognitive impairment and AD. Thus, the identification of brain activation patterns under different WM loads can potentially enhance our understanding of the mechanisms underlying cognitive dysfunction in T2DM.

RESEARCH DESIGN AND METHODS

The current study assessed the effects of T2DM on cognitive performance and explored the related neuronal damage through a visual n-back task and functional magnetic resonance imaging.

RESULTS

We found that patients with T2DM exhibited worse executive and memory abilities than control subjects. Furthermore, the patterns of brain activation changed under different WM loads in the T2DM patients, who exhibited reduced activation in the left inferior frontal gyrus under low loads and reduced activation in the left middle frontal gyrus and superior frontal gyrus (SFG) under high loads. Thus, more regions of diminished activation were seen in the frontal cortex with increasing task difficulty. Furthermore, we found that lower SFG activation was associated with worse cognitive function.

CONCLUSIONS

The findings demonstrate deficient WM in patients with T2DM and the relation between cognitive function and degree of neuronal activity and their relevance to AD risk. Further longitudinal studies are needed to replicate these results and to evaluate the clinical value of brain imaging methods in the prediction of disease progress in these patients.
Bond Durability of Different Resin Cements to Caries-Affected Dentin Under Simulated Intrapulpal Pressure
Authors: Mohamed MF , El Deeb HA , Gomaa IE , Mobarak EH
Published: November 2014

Objective:

To evaluate the durability of the bond of different resin cement systems to normal dentin (ND) and caries-affected dentin (CAD) with and without simulated intrapulpal pressure (IPP).

Methods and Materials

Molars with midcoronal caries were used. Occlusal enamel was cut to expose both dentin substrates (ND and CAD). Dentin substrates were differentiated using visual, tactile, caries-detecting dye, and dye-permeability methods. Prepared crown segments were equally divided according to the tested resin cement systems: etch-and-rinse resin cement, self-etch resin cement containing methacryloyloxydecyl dihydrogen phosphate (MDP), and self-adhesive resin cement. In addition to the dentin substrates and the resin cement types, the effect of application/storage conditions (with or without simulated IPP and with or without thermocycling) were tested. A microtensile bond strength test was done using a universal testing machine. Failure modes were determined using a scanning electron microscope.

Results

Etch-and-rinse resin cement strength values were significantly affected by the difference in the dentin substrates as well as the different application/storage conditions. Self-etch adhesive containing MDP bonded equally to ND and CAD and remained stable under all tested conditions. Self-adhesive resin cement revealed a similar bond to ND and CAD; however, its values were the lowest, especially when IPP and thermocycling were combined. Mixed failure was the predominant failure mode.

Conclusions

Etch-and-rinse resin cement was sensitive to dentin substrate and application/storage conditions. Resin cement with self-etch adhesive containing MDP revealed more reliable bonding to ND/CAD even when IPP and thermocycling were combined. The bonding of the self-adhesive resin cement could not compete with other resin cements.
Structure and mechanical properties of Zn-(5–25) Al alloys
Authors: Hekimoğlu Ali Paşa , Savaşkan Temel
Published: November 2014

In order to determine the most suitable chemical composition for the basis of zinc-based ternary and quaternary alloys, five binary Zn-(5–25) Al alloys were prepared by permanent mould casting. Their microstructures and mechanical properties were investigated using metallography and hardness, tensile and compression tests. The microstructure of Zn-5Al alloy consisted of eutectoid α + η and eutectic η phases. However, the microstructures of relatively high aluminium-containing alloys (Zn-10Al and Zn-15Al) consisted of proeutectic β dendrites surrounded by η phase and small rounded α particles. The near eutectoid alloys (Zn-20Al and Zn-25Al) exhibited similar microstructures to those of Zn-10Al and Zn-15Al alloys, but with α-cored β dendrites surrounded by α + η particles. As the aluminium content increased the hardness and strength of the alloys increased, but their impact energy and density decreased. The total percentage elongation of the alloys also decreased with aluminium content, but after showing an initial increase. These observations are discussed in terms of the microstructural features of the alloys.
Variable Speed Limit Control Strategy with Collision Probability Assessments Based on Traffic State Prediction
Authors: Fang Jie , Hadiuzzaman M. , Karim Ahsanul , Luo Ying , Qiu Tony Z.
Published: November 2014

An increasing number of vehicles on roadways has made traffic safety a serious challenge for transportation engineers. For the mitigation of traffic safety concerns, a variety of active traffic control measures, such as the variable speed limit (VSL), have been intensively investigated and deployed. VSL is usually adopted to advise drivers of a lower speed limit that is more appropriate to a congested traffic condition and takes advantage of the homogeneous traffic flow effect. However, in earlier studies, because of the absence of traffic state prediction, the impact of applied VSL control was not quantitatively analyzed. In this study, a model predictive control framework was adopted for predicting and assessing future traffic states. Taking into consideration the impact of VSL control, the study used a macroscopic traffic flow model. The collision probabilities of the predicted traffic states were assessed with a precursor-based collision prediction model to determine the optimized control signal. With this design, the proposed algorithm controller provided a robust method for determining the VSL control plan to optimize safety performance over a traffic network. The proposed control algorithm was evaluated with a simulation study based on field data that was conducted to reproduce a major ring road in Edmonton, Alberta, Canada. The proposed algorithm was used to implement VSL control on the studied 11-km freeway stretch. The proposed algorithm control scenario was then compared with the uncontrolled scenario. The evaluation proved that the proposed VSL control algorithm could effectively reduce the probability for collisions in a congested traffic network without significantly compromising mobility.
Guidance on Customization of Highway Safety Manual for Virginia
Authors: Kweon Young-Jun , Lim In-Kyu , Turpin Tracy L. , Read Stephen W.
Published: November 2014

For increased accuracy of the results of the procedures in the Highway Safety Manual (HSM), states have been encouraged to customize the procedures with local data. One way to customize the procedures is to develop calibration factors and to apply them to the default safety performance functions in the HSM. However, other ways can accomplish customization. The Virginia Department of Transportation (DOT) wants to customize the HSM procedures for the state as accurately as its resources will allow. This study examined ways to customize procedures and then developed guidance that could help a highway agency choose the best customization option for its jurisdiction. The guidance was used to recommend the best option for Virginia by using empirical data. The analysis was limited to divided segments and four-leg signalized intersections of rural multilane highways because the Virginia DOT's database provides most of the data required for developing safety performance functions and calibration factors for these two site types. The developed guidance flowchart can be used by an agency interested in customizing the HSM procedures. The flowchart can be applied with a combination of expert opinion and data analysis; a greater reliance on data analysis would require more time and resources. The guidance flowchart was applied in Virginia: a combination of Virginia's statewide safety performance functions, district-group calibration factors, and district-specific crash proportions appeared to be the best option for the state.
Analysis of Injury Severity in Crashes on Ramps and at Crossroad Ramp Terminals
Authors: Geedipally Srinivas Reddy , Bonneson James A. , Pratt Michael P. , Lord Dominique
Published: November 2014

Travel along a ramp can present drivers with complex alignment changes and decision points. These changes and complexities can increase the potential for conflict or crash, especially for larger vehicles. A few studies have examined the effect of variables on ramp crash frequency. However, none of these studies considered the effect of variables on crash severity distributions. Relatively little or no information is available about the safety effects of design elements on the severity of ramp crashes. In some cases, countermeasures (such as longitudinal barriers) are implemented to reduce fatal crashes, but the effect of these treatments on less severe crashes is not well understood. New research has been conducted to develop severity distribution functions (SDFs) for ramp segments and signalized and unsignalized crossroad ramp terminals for predicting the proportion of crashes in each severity category as a function of roadway geometric design elements and traffic control features. The SDFs were calibrated with data from California, Maine, and Washington State. The findings from this research show that barrier presence, the number of through lanes, area type, and ramp type influence the proportion of high-severity crashes on ramp segments. At the same time, access point frequency, left-turn operation, the presence of nonramp public street leg, and area type influence the proportion of high-severity crashes at crossroad ramp terminals. These SDFs can be applied along with safety performance functions and crash modification factors to obtain more precise estimates of the safety effects of design decisions.
Estimation of the Safety Effect of Pavement Condition on Rural, Two-Lane Highways
Authors: Zeng Huanghui , Fontaine Michael D. , Smith Brian L.
Published: November 2014

The condition of the pavement surface can have a significant effect on highway safety. For example, skidding crashes are often related to pavement rutting, polishing, bleeding, and dirt. When transportation agencies develop paving schedules for their roadways, the agencies often base decisions on asset management condition targets but do not explicitly account for the role of pavement condition in roadway safety. The Virginia Department of Transportation began automated data collection of pavement condition with digital images and an automated crack detection methodology in 2007. Automated collection allows the department to track historical information on pavement condition; this tracking facilitates research into the effect of pavement condition on safety. Information on how pavement condition influences safety can inform paving decisions and the setting of priorities for maintenance. This study quantitatively evaluated the safety effectiveness of good pavement conditions versus deficient pavement conditions on rural, two-lane undivided highways in Virginia. The empirical Bayes method was used to find that good pavements could reduce fatal and injury crashes by 26% compared with deficient pavements, but good pavements did not have a statistically significant impact on overall crash frequency. Further analysis indicated that there was no statistically significant change in the safety benefit of improvements in pavement condition for fatal and injury crashes as the lane or shoulder width increased. The improvement of pavement condition from deficient to good offers a significant safety benefit in reducing crash severity.
Safety Evaluation of Hybrid Main-Line Toll Plazas
Authors: Abuzwidah Muamer , Abdel-Aty Mohamed , Ahmed Mohamed M.
Published: November 2014

Traditional main-line toll plazas on expressways may have both safety and operational challenges. Although many studies have demonstrated the operational and environmental impacts of conversion from traditional toll plazas to a barrier-free system (open road tolling), research that quantifies the safety benefits of new tolling systems is lacking. This study evaluated the safety effectiveness of the conversion from a traditional main-line toll plaza design to a hybrid main-line toll plaza (HMTP) system. An HMTP system combines both open road tolling on the main line and separate traditional toll collection to the side. Various observational before–after studies were applied on 98 main-line toll plazas (two directions) located on approximately 750 mi of toll roads in Florida; 30 of these were upgraded to the HMTP system. The multivariate empirical Bayes method produced the best crash modification factors with low standard errors, and its results indicated that the conversion from traditional main-line toll plaza to HMTP showed an average crash reduction of 47%, 46%, and 54% for total crashes, fatal and injury crashes, and property-damage-only crashes, respectively. The use of an HMTP system also significantly reduced rear-end crashes and lane-change–related crashes by an average of 65% and 55%, respectively. The use of the HMTP system was proved to be an excellent solution to several traffic operations, environmental, and economic problems. The results of this study proved that the safety effectiveness was significantly improved across all locations that were upgraded to an HMTP system.
Transferability of the Highway Safety Manual Freeway Model to the Italian Motorway Network
Authors: La Torre Francesca , Domenichini Lorenzo , Corsi Francesco , Fanfani Francesco
Published: November 2014

The currently available release of the AASHTO Highway Safety Manual (HSM) does not include a model for freeways and interchanges. NCHRP Project 17–45 has recently developed specific crash prediction models for this type of infrastructure. Key to making the HSM a standard for road owners and managers worldwide is the transferability of prediction models to different networks. An extensive study conducted on the primary Italian motorway network evaluated the potential issues in application of this methodology to a network characterized by environmental conditions, road characteristics, driver attitudes, and crash reporting systems different from those for which the HSM models were developed. The freeway network considered in this study, approximately 6,700 km long, was represented by 56 freeway sections characterized by an average length of about 12.5 km, covering 700 km of freeway distributed throughout Italy. Four calibration factors were obtained for freeway segments, according to crash severity and type, and two calibration factors were obtained for speed-change lanes, according to crash severity. The results show a good transferability of the analyzed models to the Italian network, especially the freeway models for fatal and injury crashes, although a tendency to underestimate locations of high crash frequency was observed. Some improvements could be made concerning variable calibration factors within the data sets or local calibrations for crash modification factors. Improved localization of the crash data on the Italian road network needs to be highlighted, mainly for speed-change lanes.
Selection Table Development for Bridge Railing
Authors: Ray Malcolm H. , Carrigan Christine E. , Plaxico Chuck A.
Published: November 2014

Although six test levels have been available for 20 years to develop a longitudinal barrier, guidelines on how to choose bridge railings on the basis of specific site and traffic conditions have not been developed that take advantage of the range of crash-tested bridge railing hardware. The research reported in this paper was performed to develop such guidelines. During the guidelines’ development, several important issues emerged that quantified how the site, traffic, and cost characteristics of a project site should be characterized. This paper presents the issues and discusses the applied solutions. A sample set of bridge rail selection tables is presented with use of the solutions discussed, and the sample is compared with bridge railing selection tables documented in the literature. Although the specific example discussed in this paper involves the selection of bridge railings on the basis of site and traffic conditions, the same procedure can be used to develop most other roadside safety selection and location tables.
Understanding of Heavy-Vehicle Encroachment Frequency
Authors: Carrigan Christine E. , Ray Malcolm H. , Johnson T. Olaf
Published: November 2014

Encroachment data gathering in the past explicitly excluded heavy vehicles; this exclusion compelled assumptions to be made about the frequency at which heavy vehicles encroached onto the roadside. This paper examines the assumption that heavy vehicles encroach onto the roadside at the same rate as passenger vehicles. This assumption may be untrue for several reasons. In general, heavy vehicles are driven by trained professionals, who operate with additional restrictions on operating hours. Driver behavior and the performance characteristics of heavy vehicles differ from those of passenger vehicles. In this study, four data sets were analyzed: a national sample, two statewide samples, and a regional sample. The results challenged the long-held assumption that heavy vehicles encroached at the same frequency as passenger vehicles. The findings indicated that heavy vehicles encroached at approximately 30% of the rate of all vehicles. Although the causes of this reduced encroachment rate remain speculative, the examined data demonstrate that a difference does exist and should be accounted for in the modeling of run-off-road crashes for roadside safety benefit–cost and risk analyses.
Safety Investigation and Guidance for Retrofitting Existing Approach Guardrail Transitions
Authors: Schmidt Jennifer D. , Jowza Eric R. , Rosenbaugh Scott K. , Faller Ronald K. , Reid John D.
Published: November 2014

Approach guardrail transition systems have been designed, tested, and evaluated according to various impact safety standards. Unfortunately, approach guardrail transitions that are installed in the field may deviate from the as-tested configuration (e.g., by missing posts); this deviation reduces the desired lateral stiffness and strength of the transition system. Validated BARRIER VII computer models of 18-ft 9-in. (5.7-m)-long and 31-ft 3-in. (9.5-m) long systems of NCHRP Report 350 crashworthy approach guardrail transitions were used to gain an understanding of how they would perform, with and without deficiencies, when subjected to Test Level 3 impacts at various locations throughout each system. Each simulation was evaluated on the basis of three criteria: (a) maximum wheel-rim snag on the upstream edge of the bridge rail, (b) maximum dynamic deflection within the nested Thrie section, and (c) maximum vehicle pocketing angle within the nested Thrie section. According to simulation results, when transition posts were missing, installed adjacent to sloped terrain, or exposed more than 3 in. (76 mm), excessive dynamic deflection or vehicle snag on the upstream end of the bridge rail could occur. Recommendations and retrofits are provided to upgrade approach guardrail transitions for the safest performance.
Further Considerations for Effective Median Barrier Lateral Placement for Varying Highway Cross Sections
Authors: Marzougui Dhafer , Kan Cing-Dao (Steve) , Opiela Kenneth S.
Published: November 2014

The primary purpose of longitudinal median barriers is to redirect errant vehicles that depart the roadway and thus prevent collisions with opposing traffic, terrain features, or roadside objects, which could lead to severe impacts. In the study reported in this paper, vehicle dynamics analysis was used to identify the influences of varying median configurations on interface effectiveness of barrier lateral placement options. The same approach taken in previous efforts to consider five vehicle types for a range of impact conditions was taken here, except that only uniform median configurations were considered. The variations in median shape, side slopes, and roadway elevations in the analyses were reflected in nonsymmetrical override and underride limits. Data for a road section under consideration for median improvement provided the basis for the assessment of the effects of variations in median configuration. Placement effectiveness plots were generated with vehicle dynamics tools for two barrier designs. The results showed effects on lateral placement locations resulted from atypical median configurations and in situations in which there was variation in the relative elevations of the roadways on a divided highway. The results suggested a need to consider the effects of transitions in the median configuration when the barrier type and the lateral position are selected for the full length of a project. The results enhanced understanding of the effectiveness of median barrier placement with various median configurations and barrier options.