bluuebunny/crossref_metadata_2025 huggingface dataset:
Fluid effect on hydraulic fracture propagation behavior: a comparison between water and supercritical CO2‐like fluid
Authors: Zhou X. , Burbey T. J.
Published: September 2013

The initiation of hydraulic fractures during fluid injection in deep formations can be either engineered or induced unintentionally. Upon injection of CO2, the pore fluids in deep formations can be changed from oil/saline water to CO2 or CO2 dominated. The type of fluid is important not only because the fluid must fracture the rock, but also because rocks saturated with different pore fluids behave differently. We investigated the influence of fluid properties on fracture propagation behavior by using the cohesive zone model in conjunction with a poroelasticity model. Simulation results indicate that the pore pressure fields are very different for different pore fluids even when the initial field conditions and injection schemes (rate and time) are kept the same. Low viscosity fluids with properties of supercritical CO2 will create relatively thin and much shorter fractures in comparison with fluids exhibiting properties of water under similar injection schemes. Two significant times are recognized during fracture propagation: the time at which a crack ceases opening and the later time point at which a crack ceases propagating. These times are very different for different fluids. Both fluid compressibility and viscosity influence fracture propagation, with viscosity being the more important property. Viscosity can greatly affect hydraulic conductivity and the leak‐off coefficient. This analysis assumes the in‐situ pore fluid and injected fluid are the same and the pore space is 100% saturated by that fluid at the beginning of the simulation.
A case−control study of elective hip surgery among HIV‐infected patients: exposure to systemic glucocorticoids significantly increases the risk
Authors: Kerr E , Middleton A , Churchill D , Reading I , Walker‐Bone K
Published: September 2013

Objectives

This was a cross‐sectional study with a nested case−control analysis among a cohort of HIV‐infected adults aiming to explore the prevalence of and risk factors for elective hip surgery (total hip arthroplasty and resurfacing).

Methods

Cases were identified from the out‐patient database of HIV‐infected adults attending one tertiary hospital service. For each case, five controls from the same database matched by age, gender and ethnicity were identified. From the case notes, information about demographic factors, HIV factors and risk factors for hip surgery attributable to osteoarthritis or avascular necrosis (body mass index, lipids, alcohol, comorbidities and treatment with oral glucocorticoids) was extracted.

Results

Among the cohort of 1900 HIV‐infected out‐patients, 13 cases (12 male) who had undergone hip surgery [0.7%; 95% confidence interval (CI) 0.3−1.1%] were identified, with a median age of 47 years. Eleven of the 13 cases (85%) were Caucasian and seven of the 13 were in stage 3 of HIV infection. Fewer of the cases were in the asymptomatic stage of infection compared with controls [odds ratio (OR) for stage 2 or 3 infection 4.0; 95% CI 0.8–18.5]. Ever having used oral glucocorticoids was highly significantly associated with elective hip surgery (OR 44.6; 95% CI 5.7–347.7).

Conclusions

Among this young cohort, the prevalence of elective hip surgery was 0.7%, with the median age at surgery being 47 years. Ever having been exposed to systemic glucocorticoids was highly significantly associated with elective hip surgery, suggesting that the principal mechanism underlying the need for surgery was avascular necrosis. There may be an increased need for elective hip surgery associated with HIV infection.
Efficacy of various irrigation protocols on the removal of triple antibiotic paste
Authors: Arslan H. , Capar I. D. , Saygili G. , Uysal B. , Gok T. , Ertas H. , Topcuoglu H. S.
Published: September 2013

Aim

To compare the efficacy of irrigation protocols on the removal of triple antibiotic paste (metronidazole, ciprofloxacin and minocycline) (TAP) from artificial grooves in root canals.

Methodology

Root canals in 72 extracted single‐rooted teeth were prepared using ProTaper rotary instruments up to size F5. The roots were split longitudinally and a standardized groove was prepared in the apical part of one segment. TAP was placed in the grooves, and the root halves were reassembled. The roots were randomly divided into six experimental groups according to the irrigation protocol used: distilled water, 1% NaOCl, 2.5% NaOCl, 100% ethanol, 17% EDTA and passive ultrasonic irrigation (PUI) with 1% NaOCl. The root segments were disassembled, and the amount of TAP remaining was evaluated under a stereomicroscope at 20× magnification using a four‐grade scoring system. The data were evaluated statistically using Kruskal–Wallis and Mann–Whitney U‐tests with a 95% confidence level (P = 0.05).

Results

There were significant differences amongst the groups (P < 0.001). Passive ultrasonic irrigation (PUI) with 1% NaOCl removed significantly more TAP than the other irrigating solutions (P < 0.05). Distilled water, 1% NaOCl, ethanol and EDTA were associated with significantly more remaining TAP.

Conclusions

PUI with 1% NaOCl was more effective in removing TAP from artificial grooves in root canals than other irrigating solutions without ultrasonic agitation. It was not possible completely to remove TAP from root canals.
Isolation, characterisation and sulphation of soluble polysaccharides isolated from Cucurbita maxima
Authors: Zhou Chun‐Li , Liu Wei , Kong Qian , Song Yi , Ni Yuan‐Ying , Li Quan‐Hong , O'Riordan Dolores
Published: September 2013

Using hot water extraction, a large number of polysaccharides were obtained from Cucurbita maxima. A DEAE‐Sepharose CL‐6B chromatography column was used to isolate the major polysaccharides from C. maxima. Two fractions were obtained (LP2‐1 and LP2‐2). LP2‐1 and LP2‐2 consisted of neutral polysaccharides (MW: 1.02 × 104 and 4.32 × 108 g mol−1, respectively) comprised mainly of galactose units. Analyses by FT‐IR spectrometry, partial acid hydrolysis, periodate oxidation, Smith degradation and GC‐MS indicated that LP2‐1 consisted of 85.3% (1→4) glycosidic linkages and 1.7% (1→3) or (1→6) glycosidic linkages. The LP2‐1 backbone consisted of (1→4)‐linked galactose units, which occasionally branched at O6 or O3. The branches were composed of (1→4)‐linked galactose and terminated with galactose (13%). Two sulphated derivatives (SLP2‐1 and SLP2‐2) with variable degrees of sulphation (DS) were obtained by the sulphur trioxide–pyridine method, without degradation of the polysaccharide. DS of PL2‐1 and PL2‐2 was 0.19 and 0.20, respectively.
Predictors of in-Hospital Death and Symptomatic Intracranial Hemorrhage in Patients with Acute Ischemic Stroke Treated with Thrombolytic Therapy: Paul Coverdell Acute Stroke Registry 2008–2012
Authors: Tong Xin , George Mary G. , Yang Quanhe , Gillespie Cathleen
Published: September 2013

Background

Limited studies exist on the outcome of thrombolytic therapy of acute ischemic stroke patients outside of clinical trials.

Aim

To assess the possible risk factors associated with in-hospital death and symptomatic intracerebral hemorrhage among patients who received intravenous tissue plasminogen activator.

Methods

A total of 7193 patients with a clinical diagnosis of acute ischemic stroke and a documented National Institutes of Health Stroke Scale score were treated with intravenous tissue plasminogen activator within 4·5 hours of time last known to be well. Generalized estimating equations modeling was used to assess the associations of in-hospital death and symptomatic intracerebral hemorrhage with clinical characteristics.

Results

Among 7193 patients treated with intravenous tissue plasminogen activator, 516 (7·2%) died during hospitalization. Factors associated with in-hospital death were older age, male gender, National Institutes of Health Stroke Scale score, history of myocardial infarction or coronary artery disease, and history of nonvalvular atrial fibrillation. Increasing age, higher National Institutes of Health Stroke Scale score, and history of dyslipidemia were associated with symptomatic intracerebral hemorrhage. There was no difference in the rates of in-hospital death or symptomatic intracerebral hemorrhage among patients treated with intravenous tissue plasminogen activator within three-hours of time last known to be well and those treated between three and 4·5 hours after this time.

Conclusions

In this study of acute ischemic stroke patients, older age, male gender, National Institutes of Health Stroke Scale score, history of myocardial infarction or coronary artery disease, and history of atrial fibrillation were associated with increased in-hospital death among patients receiving intravenous tissue plasminogen activator. Among patients treated with intravenous tissue plasminogen activator, in-hospital mortality and symptomatic intracerebral hemorrhage rates were similar between those treated within three-hours of time last known to be well and those treated between three and 4·5 hours after this time.
Elevated Thyroid Autoantibodies and Intracranial Stenosis in Stroke at an Early Age
Authors: Shi Zhenghao , Zhang Xuting , Chen Zhicai , Liebeskind David S. , Lou Min
Published: September 2013

Background

Previous studies have shown that hyperthyroidism was related to Moyamoya disease and intracranial artery stenosis. However, it is not clear whether thyroid hormone or thyroid autoantibodies was associated with them.

Aims and/or hypothesis

Thyroid autoimmunity was previously shown to be associated with Moyamoya disease. Our study aimed to investigate the association between thyroid autoantibodies and intracranial large artery stenosis in young ischemic stroke patients with apparent euthyroid states.

Methods

We retrospectively reviewed first-onset ischemic stroke patients (age ≤55 years old) consecutively admitted to a single academic center. Intracranial large artery stenosis was defined as ≤50% luminal diameter narrowing. We compared demographic profiles, risk factors (age, hypertension, diabetes, current smoker, atrial fibrillation, hyperlipidemia), thyroid function test, and thyroid autoantibodies including antithyroperoxidase antibody and antithyroglobulin antibody between patients with and without intracranial large artery stenosis. We also performed multivariate logistic regression analysis to evaluate the association between thyroid autoantibodies and intracranial large artery stenosis.

Results

A total of 351 patients were analyzed. The mean age of the patients was 47·0 ±7·7 (range, 10–55 years), and 252 (71·8%) patients were male. We identified intracranial large artery stenosis in 121 (34·5%) patients. Patients with intracranial large artery stenosis showed a higher frequency of elevated antithyroperpxidase antibody levels in comparison with nonintracranial large artery stenosis group (16·5% vs. 3·9%, P < 0·001). After adjusting for covariates, the presence of elevated antithyroperpxidase antibody levels (odds ratio: 5·318; 95% confidence interval: 2·157–13·110, P <0·001), age (odds ratio: 1·037; 95% confidence interval: 1·002–1·073, P = 0·039), and atrial fibrillation (odds ratio: 0·091; 95% confidence interval: 0·011–0·756, P = 0·027) was independently associated with intracranial large artery stenosis.

Conclusions

Thyroid autoantibodies may be associated with the presence of intracranial large artery stenosis in young stroke patients, potentially providing insight on immune pathogenesis of intracranial large artery stenosis.
In-Hospital Cardiac Complications after Intracerebral Hemorrhage
Authors: Putaala J. , Lehto M. , Meretoja A. , Silvennoinen K. , Curtze S. , Kääriäinen J. , Koivunen R.-J. , Kaste M. , Tatlisumak T. , Strbian D.
Published: September 2013

Background and purpose

Data on cardiac complications and their precipitants after intracerebral hemorrhage are scarce. We examined the frequency and risk factors for serious in-hospital cardiac events in a large cohort of consecutive intracerebral hemorrhage patients.

Methods

A retrospective chart review of 1013 consecutive patients with nontraumatic intracerebral hemorrhage treated at the Helsinki University Central Hospital (2005–2010). We excluded patients with intraparenchymal hematoma related to sub-arachnoid hemorrhage or intracerebral hemorrhage because of fibrinolytic therapies for acute ischemic stroke or myocardial infarction. Serious in-hospital cardiac event was defined as any of in-hospital poststroke acute myocardial infarction, ventricular fibrillation or tachycardia, moderate to serious acute heart failure, or cardiac death.

Results

Among the 948 patients included, ≥1 serious in-hospital cardiac event occurred in 39 (4·1%) patients after a median delay of two-days from stroke onset (acute myocardial infarction in three patients, ventricular fibrillation or tachycardia in three patients, acute heart failure in 36 patients, and cardiac death in three patients). Hospital stay was longer in patients with serious in-hospital cardiac event than in those without (median 12, interquartile range 7–19 vs. 8, 3–14; P = 0·001), with no difference in in-hospital mortality (23·1% vs. 24·3%; P = 0·86). In multivariable logistic regression analysis adjusted for age, gender, and diabetes, atrial fibrillation during hospitalization (odds ratio 6·68 for new-onset atrial fibrillation, 95% confidence interval 2·11–21·18; 4·46 for old atrial fibrillation, 2·08–9·56), and history of myocardial infarction (3·20, 1·18–8·66) were independently associated with serious in-hospital cardiac events.

Conclusions

After intracerebral hemorrhage, 4% of patients suffer an acute serious cardiac complication. Those with history of myocardial infarction or in-hospital atrial fibrillation are at greater risk for such events.
Short-Duration Hypothermia after Ischemic Stroke Prevents Delayed Intracranial Pressure Rise
Authors: Murtha L. A. , McLeod D. D. , McCann S. K. , Pepperall D. , Chung S. , Levi C. R. , Calford M. B. , Spratt N. J.
Published: September 2013

Background

Intracranial pressure elevation, peaking three to seven post-stroke is well recognized following large strokes. Data following small–moderate stroke are limited. Therapeutic hypothermia improves outcome after cardiac arrest, is strongly neuroprotective in experimental stroke, and is under clinical trial in stroke. Hypothermia lowers elevated intracranial pressure; however, rebound intracranial pressure elevation and neurological deterioration may occur during rewarming.

Hypotheses

( 1 ) Intracranial pressure increases 24 h after moderate and small strokes. ( 2 ) Short-duration hypothermia-rewarming, instituted before intracranial pressure elevation, prevents this 24 h intracranial pressure elevation.

Methods

Long-Evans rats with two hour middle cerebral artery occlusion or outbred Wistar rats with three hour middle cerebral artery occlusion had intracranial pressure measured at baseline and 24 h. Wistars were randomized to 2·5 h hypothermia (32·5°C) or normothermia, commencing 1 h after stroke.

Results

In Long-Evans rats ( n = 5), intracranial pressure increased from 10·9 ± 4·6 mmHg at baseline to 32·4 ± 11·4 mmHg at 24 h, infarct volume was 84·3 ± 15·9 mm3. In normothermic Wistars ( n = 10), intracranial pressure increased from 6·7 ± 2·3 mmHg to 31·6 ± 9·3 mmHg, infarct volume was 31·3 ± 18·4 mm3. In hypothermia-treated Wistars ( n = 10), 24 h intracranial pressure did not increase (7·0 ± 2·8 mmHg, P < 0·001 vs. normothermia), and infarct volume was smaller (15·4 ± 11·8 mm3, P < 0·05).

Conclusions

We saw major intracranial pressure elevation 24 h after stroke in two rat strains, even after small strokes. Short-duration hypothermia prevented the intracranial pressure rise, an effect sustained for at least 18 h after rewarming. The findings have potentially important implications for design of future clinical trials.
Advantages of aviaries and the Aviary Database Project: a new approach to an old housing option for birds
Authors: Bračko A. , King C. E.
Published: September 2013

There is a trend in zoos to provide more naturalistic enclosures for animals in which they can carry out natural behaviours and, for most birds, an aviary presents the best opportunities to achieve this. Reasons for holding birds in aviaries, including education and visitor experience, breeding, behaviour, predation, veterinary issues, avoidance of invasive species and hybridization, welfare and enrichment, and reductions in costs, are discussed. The development of the Aviary Database Project is explained. This information‐sharing resource is in development and will be a tool for exchanging knowledge and experiences in designing and constructing aviaries, and selecting the best aviary for the species in question and for the geographic location. Zoos may be able to avoid expensive mistakes and optimize their possibilities by sharing information on aspects such as costs, visitor viewing, suitable materials and design features. By lowering the barriers in the way of building appropriate aviaries, it is hoped that this type of housing will become the option of choice in future master plans. While adopting an aviary strategy for housing all ‘flying’ birds may result in a reduction in the number of species at a zoo, and could affect both institutional and regional collection plans, we believe it is a necessary step in order to provide the optimal conditions for the care and well‐being of the birds that are already in zoological institutions.
Linking ‘10‐year’ herbivore cycles to the lunisolar oscillation: the cosmic ray hypothesis
Authors: Selås Vidar
Published: September 2013

The mean population cycle periods of the snowshoe hare Lepus americanus, the larch budmoth Zeiraphera diniana, and the autumnal moth Epirrita autumnata are 9.3 years, similar to the lunar nodal phase cycle. When the full/new Moon is situated close to the ecliptic plane at solstice, it interacts more strongly with the magnetosphere, which plays a crucial role in protecting the Earth against ionizing cosmic ray particles. Ionization by cosmic rays induces protein mobilization in plants, which may increase forage quality for herbivores. Series of hare/lynx population indices from Canadian provinces and an autumnal moth series from Fennoscandia correlated with the lunar nodal phase cycle with different time lags. Both the time lag and the impact of an active sun, which increases solar energetic particles, but decreases galactic cosmic ray particles, were related to radiation or the distance from the auroral oval. These insights improve our ability to explain and understand population peaks, and should also motivate further studies on the effects of cosmic rays on plant chemistry and herbivore performance.
The role of belowground competition and plastic biomass allocation in altering plant mass–density relationships
Authors: Lin Yue , Huth Franka , Berger Uta , Grimm Volker
Published: September 2013

Metabolic scaling theory (MST) predicts a ‘universal scaling law’ for plant mass–density relationships, but empirical observations are more variable. Possible explanations of this variability include plasticity in biomass allocation between the above‐ and belowground compartment and different modes of competition, which can be asymmetric or symmetric. Although complex interactions of these factors are likely to occur, so far the majority of modelling and empirical studies has focussed on mono‐factorial explanations. We here present a generic individual‐based model, which allows exploring the plant mass–density relationship in realistic settings by representing plasticity of biomass allocation and different modes of competition in the above‐ and belowground compartment. Plants grew according to an ontogenetic growth model derived from MST. To evaluate the behavior of the simulated plants related to the allocation patterns and to validate model predictions, we conducted greenhouse experiments with tree seedlings. The model reproduced empirical patterns both at the individual and population level. Without belowground resource limitation, aboveground processes dominated and the slopes of mass–density relationships followed the predictions of MST. In contrast, resource limitation led to an increased allocation of biomass to belowground parts of the plants. The subsequent dominance of symmetric belowground competition caused significantly shallower slopes of the mass–density relationship, even though the growth of individual plants followed MST. We conclude that changes in biomass allocation induced by belowground resource limitation explain the deviations from the mass–density relationship predicted by MST. Taking into account the plasticity of biomass allocation and its linkage to the above‐ and belowground competition is critical for fully representing plant communities, in particular for correctly predicting their response of carbon storage and sequestration to changing environmental conditions.
Preferential phenotypic association linked with cooperation in paper wasps
Authors: Tibbetts E. A. , Injaian A.
Published: September 2013

Animals can influence their social environment by preferentially associating with certain conspecifics. Such preferential association has gained increasing theoretical attention, as it may influence social evolution and population dynamics. However, relatively little empirical work has examined the occurrence of preferential association and its effects on cooperative group formation. Here, we test the factors associated with cooperative group formation inPolistes dominulusnest‐founding queen wasps.P. dominulusare a good system to study preferential association, as foundresses can nest alone or in groups and group membership is flexible. We found that both social and environmental factors were associated with partner choice. First, facial patterns were associated with cooperation. Wasps with more similar facial patterns were more likely to cooperate than wasps with less similar facial patterns. This preferential phenotypic association fits the theoretical criteria for the evolution of tag‐based cooperation. Season was also associated with cooperation; wasps on early‐season nests were more likely to cooperate than wasps on late‐season nests. High levels of aggression by nest owners during initial interactions were also correlated with lower probabilities of subsequent cooperation, suggesting that nest owners have some control over group membership. Other factors including body weight, weight similarity and nest productivity were not linked with cooperation. Overall, multiple factors influence cooperation in paper wasps, including facial pattern similarity. The occurrence of preferential phenotypic association in paper wasps is quite interesting and may influence the evolution of cooperation and population divergence in this group.
Change to Either a Nonandrogenic or Androgenic Progestin-Containing Oral Contraceptive Preparation is Associated with Improved Sexual Function in Women with Oral Contraceptive-Associated Sexual Dysfunction
Authors: Davis Susan R. , Bitzer Johannes , Giraldi Annamaria , Palacios Santiago , Parke Susanne , Serrani Marco , Mellinger Uwe , Nappi Rossella E.
Published: September 2013

Introduction

It is a commonly held belief that combined oral contraceptive (COC) pills containing an androgenic progestin may be less likely to impair sexual function than COCs containing an anti-androgenic progestin.

Aim

The study aims to compare the effects of a COC containing a progestin with an anti-androgenic profile (estradiol valerate [E2V]/dienogest [DNG]) to that of one with an androgenic progestin (ethinyl estradiol [EE]/levonorgestrel [LNG]) on sexual function in women with COC-associated sexual dysfunction.

Methods

In this multicenter, randomized, double-blind, noninferiority study, women with COC-associated female sexual dysfunction (FSD) were randomized to E2V/DNG or EE/LNG for six cycles. The primary outcome was the change in the sum of Female Sexual Function Index (FSFI) desire and arousal component scores between baseline and cycle 6. Secondary outcome measures included changes to the FSFI domains, the Female Sexual Distress Scale (FSDS-R), Vaginal Health Assessment, the Atrophy Symptom Questionnaire, and the Psychological General Well Being Index over six treatment cycles.

Main Outcome Measure

The main outcome is the change in the sum of FSFI desire and arousal component scores between baseline and cycle 6.

Results

Of 276 women screened, 213 received treatment and 191 completed the study. The mean increase in the sum of FSFI desire and arousal component scores was 5.90 (standard deviation [SD] 5.45) for E2V/DNG and 5.79 (SD 6.17) for EE/LNG (change from baseline P < 0.0001, both groups). Both treatments showed equal efficacy and were associated with improvements in all domains of the FSFI, with no between-group differences. Both COCs reduced the distress associated with FSD, as indicated by reduced FSDS-R scores.

Conclusion

In women with COC-associated FSD, switching to either E2V/DNG or EE/LNG was associated with equivalent improvements in symptoms, challenging the perception that COCs containing anti-androgenic progestins have a detrimental effect on sexual function relative to those containing androgenic progestins.
Stable isotope analysis of carbon and nitrogen in angrites
Authors: Abernethy F. A. J. , Verchovsky A. B. , Starkey N. A. , Anand M. , Franchi I. A. , Grady Monica M.
Published: September 2013

Angrites are a small group of ancient basaltic achondrites, notable for their unusual chemistry and extreme volatile depletion. No comprehensive study of indigenous light elements currently exists for the group. Measurement of the abundances and isotopic composition of carbon and nitrogen could provide information pertaining to the evolution of the angrite parent body. Bulk‐sample stepped combustion analyses of five angrites and a glass separate from D'Orbigny were combined with earlier data and acid dissolution experiments of carbonates found in D'Orbigny to compile an inventory of indigenous carbon and nitrogen. Indigenous carbon combusted between 700 °C and 1200 °C, with abundances of 10–140 ppm and a mass‐weighted δ13C of −25 to −20‰ with the exception of D'Orbigny (δ13C approximately −5‰). Nitrogen was released at 850–1200 ºC, 1–20 ppm with a δ15N −3‰ to +4‰; again, D'Orbigny (δ15N approximately +20 to +25‰) was an exception. We interpret these components as largely indigenous and decoupled; the carbon in graphitic or amorphous form, while the nitrogen is present as a dissolved component in the silicates. No relationship with the textural sub‐classification of angrites is apparent. We suggest that the angrite parent body contains a reservoir of reduced carbon and thus may have undergone a change in redox conditions, although the timing and mechanism for this remain unclear.
An inordinate fondness for beetles? Variation in seasonal dietary preferences of night‐roosting big brown bats (Eptesicus fuscus)
Authors: Clare Elizabeth L. , Symondson William O. C. , Fenton Melville Brockett
Published: September 2013

Generalist species with numerous food web interactions are thought to provide stability to ecosystem dynamics; however, it is not always clear whether habitat generality translates into dietary diversity. Big brown bats are common across North America and employ a flexible foraging strategy over water, dense forests, forest edges and rural and urban settings. Despite this generalist use of habitat, they are paradoxically characterized as beetle specialists. However, hard carapaces may preferentially survive digestion leading to over‐representation during morphological analysis of diet. This specialization has not been evaluated independently using molecular analysis and species‐level identification of prey. We used next‐generation sequencing to assess the diet of big brown bats. Beetles were consumed in the highest frequency but Lepidoptera species richness was highest among identified prey. The consumption of species showed strong seasonal and annual variation. While Coleoptera consumption varied, Lepidoptera and Ephemeroptera were relatively constant dietary components. Dietary diversity increased in late summer when insect diversity decreases. Our results indicate that big brown bats are dietary generalists and, while beetles are an important component of the diet, Lepidoptera are equally important, and Lepidoptera and Ephemeroptera are the only stable prey resource exploited. As resources become limited, big brown bats may respond by increasing the species richness of prey and thus their connectedness in the ecosystem. This characterization of diet corresponds well with a generalist approach to foraging, making them an important species in encouraging and maintaining ecosystem stability.
A Tabu Search Method for a Bi‐Objective Urban Waste Collection Problem
Authors: Gómez José Rubén , Pacheco Joaquín , Gonzalo‐Orden Hernán
Published: September 2013

A bi‐objective model for the collection of waste bins in rural areas within a planning period is analyzed. This model is a real problem raised by local authorities in a rural region of northwestern Spain. The two objectives under consideration are: minimization of transport costs and improvements to the level of service. Specifically, the level of service depends on the frequency of waste collection at each point over the planning period. A solution method for this problem was developed by applying tabu search within the framework of Multiobjective Adaptive Memory Programming (MOAMP) and the results were compared with an implementation of NSGA‐II, a well‐known approach to multiobjective optimization.
Independent target region amplification polymorphism and single‐nucleotide polymorphism marker utility in genetic evaluation of sugarcane genotypes
Authors: Devarumath Rachayya M. , Kalwade Sachin B. , Bundock Peter , Eliott Frances G. , Henry Robert
Published: September 2013

The independent target region amplification polymorphism (TRAP) and single‐nucleotide polymorphism (SNP) markers were used for genetic evaluation of different selected 47 sugarcane genotypes. A total of 23 pairs of TRAP markers generated 925 alleles, of which 74% alleles were polymorphic. Polymorphism was generally high (>50%), ranging from 54 to 98%. The polymorphism information content (PIC) values 0.20 varied among the primer combination ranging from 0.17 in SAI + Arbi 2 to 0.31 in GL 2+ Arbi 1 with an average of 0.24. However, the Pearson correlation between PIC and power of discrimination (PD) was found to be less significant. Single‐nucleotide polymorphisms were used first time for the assessment of genetic diversity among different species of Saccharum and cultivated sugarcane varieties. The SNPs were detected from 454 sequencing. A total of 245 SNP markers were assayed across the 47 genotypes, and 167 SNPs were found to be polymorphic. The PIC values ranged from 0.04 to 0.38 with an average of 0.21, and their respective PD varied from 0.58 to 0.04 with an average value of 0.31. The obtained results relatively significant were compared with the other marker systems through genetic similarity and the clusters formed in different unweighted pair group method with arithmetic mean clustering dendrogram. The clustering analysis established genetic relationship in the order of Erianthus > Sclerostachya > Narenga > Saccharum spontaneum > S. robustum > S. barberi > S. officinarum/cultivars. These results ratify TRAP and SNP marker systems for assessing genetic diversity studies, and more diversified Erianthus spp. can contribute substantially towards sugarcane varietal improvement through breeding with Saccharum spp. or hybrid cultivars.
Underground Markets as Fields in Transition: Sex Work in New York City
Authors: Venkatesh Sudhir
Published: September 2013

Most ethnographers visualize their fieldwork study vis‐à‐vis their long‐term commitment to a bounded sociospatial context—an “ecology.” In this manner, the majority of ethnographic studies are presented as studies not only of practices but also of recognizable physical ecologies that breathe life into the practices—for example, homes, ghettos, firms, schools, and so on. In the pages that follow, I consider the ways in which the status of place has shifted in urban sex work. The shifting commerce of sexual services in New York enables me to open up a set of methodological issues about the role of space in ethnographic work. One in particular is at the core of this paper: namely, because so many ethnographic labors begin with the selection of a field site, what conceptual issues arise that fieldworkers must pay attention to vis‐à‐vis that decision? For example, the field site may change, the field site may itself be shaped by wider societal forces, and it may be simply dissolve over time. How does any of this impact a technique that is premised on the dependability of “sitting” so that others may be dependably followed? I draw on the notion of “strategic action fields” to present an alternative analytic framework, one more useful for the challenges ethnographers face.
Serial viscoelastic and traditional coagulation testing in horses with gastrointestinal disease
Authors: Epstein Kira L. , Brainard Benjamin M. , Giguere Steeve , Vrono Zachary , Moore James N.
Published: September 2013

Objective

Objectives of this study were to compare the ability of serial thromboelastography, Sonoclot, and traditional coagulation panels to detect coagulopathies associated with disease category, systemic inflammatory response syndrome (SIRS), complications, and nonsurvival in horses with gastrointestinal disease.

Design

Prospective clinical evaluation.

Setting

University referral hospital.

Animals

One hundred twenty‐one horses admitted as emergencies for gastrointestinal disease and 28 healthy adult horses.

Intervention

Blood samples were collected ≤4 times from emergency horses (admission and if surviving and hospitalized on days 2–4) and once from healthy horses. Thromboelastography (with and without tissue factor activation), Sonoclot, and a traditional coagulation panel were performed on each sample.

Measurements and Main Results

Emergency horses were grouped based on disease category (ie, nonstrangulating medical, nonstrangulating surgical, strangulating, and inflammatory), survival to discharge, SIRS at admission, requirement for exploratory celiotomy, ileus, diarrhea, fever, thrombophlebitis, and laminitis. Changes over time were evaluated individually and compared between disease groups. Horses with gastrointestinal disease had dynamic changes in coagulation and fibrinolysis during the first 4 days of hospitalization that were correlated with disease category, SIRS, complications, and fatality. The multivariate logistic regression model for nonsurvival included activated partial thromboplastin time on day 2 and LY30 on day 3 (overall model significanceP< 0.0001). The odds of nonsurvival were 23.75 times higher if activated partial thromboplastin time was >85.6 s on day 2 and 9.38 times higher if LY30 was >1% on day 3.

Conclusions

Horses with gastrointestinal disease have activation of coagulation and fibrinolysis. Magnitude of change in these parameters is small and predictive value moderate, making application of these tests to direct therapy in clinical patients difficult. Effect of specific treatments (eg, surgery) on these tests and coagulation has not been determined. Further studies are required to determine if these tests could be used to help monitor response to treatment in individual animals or specific disease states.
The Role of Porous Media in Homogenization of High Pressure Diesel Fuel Spray Combustion
Authors: Shahangian Navid , Honnery Damon , Ghojel Jamil
Published: September 2013

Interest is growing in the benefits of homogeneous charge compression ignition engines. In this paper, we investigate a novel approach to the development of a homogenous charge-like environment through the use of porous media. The primary purpose of the media is to enhance the spread as well as the evaporation process of the high pressure fuel spray to achieve charge homogenization. In this paper, we show through high speed visualizations of both cold and hot spray events, how porous media interactions can give rise to greater fuel air mixing and what role system pressure and temperature plays in further enhancing this process.
Wiener–Askey and Wiener–Haar Expansions for the Analysis and Prediction of Limit Cycle Oscillations in Uncertain Nonlinear Dynamic Friction Systems
Authors: Nechak Lyes , Berger Sébastien , Aubry Evelyne
Published: September 2013

This paper is devoted to the robust modeling and prediction of limit cycle oscillations in nonlinear dynamic friction systems with a random friction coefficient. In recent studies, the Wiener–Askey and Wiener–Haar expansions have been proposed to deal with these problems with great efficiency. In these studies, the random dispersion of the friction coefficient is always considered within intervals near the Hopf bifurcation point. However, it is well known that friction induced vibrations—with respect to the distance of the friction dispersion interval to the Hopf bifurcation point—have different properties in terms of tansient, frequency and amplitudes. So, the main objective of this study is to analyze the capabilities of the Wiener–Askey (general polynomial chaos, multielement generalized polynomial chaos) and Wiener–Haar expansions to be efficient in the modeling and prediction of limit cycle oscillations independently of the location of the instability zone with respect to the Hopf bifurcation point.
Cyclic Combustion Variations in Dual Fuel Partially Premixed Pilot-Ignited Natural Gas Engines
Authors: Srinivasan K. K. , Krishnan S. R. , Qi Y.
Published: September 2013

Dual fuel pilot-ignited natural gas engines are identified as an efficient and viable alternative to conventional diesel engines. This paper examines cyclic combustion fluctuations in conventional dual fuel and in dual fuel partially premixed combustion (PPC). Conventional dual fueling with 95% (energy basis) natural gas (NG) substitution reduces NOx emissions by almost 90% relative to neat diesel operation; however, this is accompanied by 98% increase in HC emissions, 10 percentage points reduction in fuel conversion efficiency (FCE) and 12 percentage points increase in COVimep. Dual fuel PPC is achieved by appropriately timed injection of a small amount of diesel fuel (2–3% on an energy basis) to ignite a premixed natural gas–air mixture to attain very low NOx emissions (less than 0.2 g/kWh). Cyclic variations in both combustion modes were analyzed by observing the cyclic fluctuations in start of combustion (SOC), peak cylinder pressures (Pmax), combustion phasing (Ca50), and the separation between the diesel injection event and Ca50 (termed “relative combustion phasing”). For conventional dual fueling, as NG substitution increases, Pmax decreases, SOC and Ca50 are delayed, and cyclic variations increase. For dual fuel PPC, as diesel injection timing is advanced from 20 deg to 60 deg BTDC, Pmax is observed to increase and reach a maximum at 40 deg BTDC and then decrease with further pilot injection advance to 60 deg BTDC, the Ca50 is progressively phased closer to TDC with injection advance from 20 deg to 40 deg BTDC, and is then retarded away from TDC with further injection advance to 60 deg BTDC. For both combustion modes, cyclic variations were characterized by alternating slow and fast burn cycles, especially at high NG substitutions and advanced injection timings. Finally, heat release return maps were analyzed to demonstrate thermal management strategies as an effective tool to mitigate cyclic combustion variations, especially in dual fuel PPC.
Graphic Processing Units (GPUs)-Based Haptic Simulator for Dental Implant Surgery
Authors: Zheng Fei , Feng Lu Wen , San Wong Yoke , Weng Chiong Foong Kelvin
Published: September 2013

This paper presents a haptics-based training simulator for dental implant surgery. Most of the previously developed dental simulators are targeted for exploring and drilling purpose only. The penalty-based contact force models with spherical-shaped dental tools are often adopted for simplicity and computational efficiency. In contrast, our simulator is equipped with a more precise force model adapted from the Voxmap-PointShell (VPS) method to capture the essential features of the drilling procedure, with no limitations on drill shape. In addition, a real-time torque model is proposed to simulate the torque resistance in the implant insertion procedure, based on patient-specific tissue properties and implant geometry. To achieve better anatomical accuracy, our oral model is reconstructed from cone beam computed tomography (CBCT) images with a voxel-based method. To enhance the real-time response, the parallel computing power of GPUs is exploited through extra efforts in data structure design, algorithms parallelization, and graphic memory utilization. Results show that the developed system can produce appropriate force feedback at different tissue layers during pilot drilling and can create proper resistance torque responses during implant insertion.
Optimal Perturbations in Boundary-Layer Flows Over Rough Surfaces
Authors: Cherubini S. , de Tullio M. D. , De Palma P. , Pascazio G.
Published: September 2013

This work provides a three-dimensional energy optimization analysis, looking for perturbations inducing the largest energy growth at a finite time in a boundary-layer flow in the presence of roughness elements. The immersed boundary technique has been coupled with a Lagrangian optimization in a three-dimensional framework. Four roughness elements with different heights have been studied, inducing amplification mechanisms that bypass the asymptotical growth of Tollmien–Schlichting waves. The results show that even very small roughness elements, inducing only a weak deformation of the base flow, can strongly localize the optimal disturbance. Moreover, the highest value of the energy gain is obtained for a varicose perturbation. This result demonstrates the relevance of varicose instabilities for such a flow and shows a different behavior with respect to the secondary instability theory of boundary layer streaks.
An Alternative Formulation of the Dynamic Transmission Error to Study the Oscillations of Automotive Hypoid Gears
Authors: Karagiannis I. , Theodossiades S.
Published: September 2013

A new modeling approach on the torsional dynamics of hypoid gear pairs is presented in this work. The current formulation is characterized by an alternative expression of the dynamic transmission error (DTE), accounting for the variation of the effective mesh position. Speed dependent resistive torque is introduced on the gear wheel, enabling the system to reach dynamic equilibrium based on realistic vehicle operating conditions. The above are supplementing past research studies, where simplifications were introduced in the calculation of DTE, while the operating angular velocity was defined a priori. The analysis is accompanied by numerical results, indicating the rich dynamic behavior captured by the new formulation. The dynamic complexity of the system necessitates the identification of the various response regimes. A solution continuation method (software AUTO) is employed to follow the stable/unstable periodic response branches over the operating range of the differential under examination.
Efficient Hybrid Finite Element Method for Flutter Prediction of Functionally Graded Cylindrical Shells
Authors: Sabri Farhad , Lakis Aouni A.
Published: September 2013

In this work, a hybrid finite element formulation is presented to predict the flutter boundaries of circular cylindrical shells made of functionally graded (FG) materials. The development is based on a combination of linear Sanders thin shell theory and the classic finite element method. Material properties are temperature dependent and graded in the shell thickness direction according to a simple power law distribution in terms of volume fractions of constituents. The temperature field is assumed to be uniform over the shell surface and along the shell thickness. First-order piston theory is applied to account for supersonic aerodynamic pressure. The effects of temperature rise and shell internal pressure on the flutter boundaries of a FG circular cylindrical shell for different values of power law index are investigated. The present study shows efficient and reliable results that can be applied to aeroelastic design and analysis of shells of revolution in aerospace vehicles.
An Integrated Computational Welding Mechanics With Direct-Search Optimization for Mitigation of Distortion in an Aluminum Bar Using Side Heating
Authors: Asadi Mahyar , Goldak John A.
Published: September 2013

Using a computational weld mechanics (CWM) frame-work for exploring a design space, a recent direct-search algorithm from Kolda, Lewis and Torczon is modified to use a least-square approximation to improve the method of following a path to the minimum in the algorithm. To compare the original and modified algorithms, a CWM optimization problem on a 152 × 1220 × 12.5 mm bar of Aluminum 5052-H32 to minimize the weld distortion mitigated by a side heating technique is solved. The CWM optimization problem is to find the best point in the space of side heater design parameters: power, heated area, longitudinal and transverse distance from the weld such that the final distortion is as low as possible (minimized). This CWM optimization problem is constrained to keep the stress level generated by the side heaters, in the elastic region to avoid adding an additional permanent plastic strain to the bar. The number of iterations, size of design of experiments (DOE) matrix required and CPU time to find the minimum for the two algorithms are compared.
Algebraic Anisotropic Turbulence Modeling of Compound Angled Film Cooling Validated by Particle Image Velocimetry and Pressure Sensitive Paint Measurements
Authors: Li Xueying , Qin Yanmin , Ren Jing , Jiang Hongde
Published: September 2013

The complex structures in the film cooling flow field of gas turbines lead to the anisotropic property of the turbulent eddy viscosity and scalar diffusivity. An algebraic anisotropic turbulence model is developed aiming at a more accurate modeling of the Reynolds stress and turbulent scalar flux. In this study, the algebraic anisotropic model is validated by a series of in-house experiments for cylindrical film cooling with compound angle injection of 0, 45, and 90 deg. Adiabatic film cooling effectiveness and flow field are measured using pressure sensitive paint and particle image velocimetry techniques on film cooling test rig in Tsinghua University. Detailed analyses of computational simulations are performed. The algebraic anisotropic model gives a good prediction of the secondary vortices associated with the jet and the trajectory of the jet, therefore improves the prediction of the scalar field. On one hand, the anisotropic eddy viscosity improves the modeling of Reynolds stress and the predictive flow field. On the other hand, the anisotropic turbulent scalar-flux model includes the role of anisotropic eddy viscosity in modeling of scalar flux and directly improves the turbulent scalar flux prediction.