bluuebunny/crossref_metadata_2025 huggingface dataset:
Integrating Risk and Resilience Approaches to Catastrophe Management in Engineering Systems
Authors: Park J. , Seager T. P. , Rao P. S. C. , Convertino M. , Linkov I.
Published: September 2012

Recent natural and man‐made catastrophes, such as the Fukushima nuclear power plant, flooding caused by Hurricane Katrina, the Deepwater Horizon oil spill, the Haiti earthquake, and the mortgage derivatives crisis, have renewed interest in the concept of resilience, especially as it relates to complex systems vulnerable to multiple or cascading failures. Although the meaning of resilience is contested in different contexts, in general resilience is understood to mean the capacity to adapt to changing conditions without catastrophic loss of form or function. In the context of engineering systems, this has sometimes been interpreted as the probability that system conditions might exceed an irrevocable tipping point. However, we argue that this approach improperly conflates resilience and risk perspectives by expressing resilience exclusively in risk terms. In contrast, we describe resilience as an emergent property of what an engineering system does, rather than a static property the system has. Therefore, resilience cannot be measured at the systems scale solely from examination of component parts. Instead, resilience is better understood as the outcome of a recursive process that includes: sensing, anticipation, learning, and adaptation. In this approach, resilience analysis can be understood as differentiable from, but complementary to, risk analysis, with important implications for the adaptive management of complex, coupled engineering systems. Management of the 2011 flooding in the Mississippi River Basin is discussed as an example of the successes and challenges of resilience‐based management of complex natural systems that have been extensively altered by engineered structures.
Inferring an Augmented Bayesian Network to Confront a Complex Quantitative Microbial Risk Assessment Model with Durability Studies: Application to Bacillus Cereus on a Courgette Purée Production Chain
Authors: Rigaux Ancelet Clémence Sophie , Carlin Frédéric , Nguyen‐thé Christophe , Albert Isabelle
Published: September 2012

The Monte Carlo (MC) simulation approach is traditionally used in food safety risk assessment to study quantitative microbial risk assessment (QMRA) models. When experimental data are available, performing Bayesian inference is a good alternative approach that allows backward calculation in a stochastic QMRA model to update the experts’ knowledge about the microbial dynamics of a given food‐borne pathogen. In this article, we propose a complex example where Bayesian inference is applied to a high‐dimensional second‐order QMRA model. The case study is a farm‐to‐fork QMRA model considering genetic diversity of Bacillus cereus in a cooked, pasteurized, and chilled courgette purée. Experimental data are Bacillus cereus concentrations measured in packages of courgette purées stored at different time‐temperature profiles after pasteurization. To perform a Bayesian inference, we first built an augmented Bayesian network by linking a second‐order QMRA model to the available contamination data. We then ran a Markov chain Monte Carlo (MCMC) algorithm to update all the unknown concentrations and unknown quantities of the augmented model. About 25% of the prior beliefs are strongly updated, leading to a reduction in uncertainty. Some updates interestingly question the QMRA model.
Good News, Bad News, and Consumer Confidence
Authors: Casey Gregory P. , Owen Ann L.
Published: September 2012

Objectives

We test for asymmetric reactions of consumer confidence and the news media to changes in economic fundamentals. We examine the relationship between media reporting and consumer confidence.

Methods

Using data from the University of Michigan Index of Consumer Sentiment and a new data set on media coverage constructed by ourselves, we estimate time series regressions that explain changes in consumer confidence and media coverage of economic news.

Results

We find evidence of asymmetric reactions by consumers to changes in economic fundamentals; however, we find no evidence of a systematic negativity bias. We also find no evidence of bias in the media. The findings of asymmetric reactions are strengthened when we control for expectations.

Conclusion

Asymmetric reactions in consumer confidence depend on the nature of the economic fundamental that is changing. Reference points are important in determining consumer reaction, but they do not explain asymmetric responses.
What Explains Openness to Intercountry Adoption?
Authors: Breuning Marijke
Published: September 2012

Objective

This study systematically investigates the factors that determine sending country openness or restrictiveness regarding intercountry adoption. It hypothesizes that larger orphan populations, greater global interconnectedness, and accession to the Hague Convention are associated with greater openness, whereas the political empowerment of women and larger Islamic populations are expected to be associated with greater restrictiveness.

Methods

The study employs an original, global data set to empirically test the significance of the hypothesized factors in explaining a country's openness to intercountry adoption.

Results

The study finds that burgeoning orphan populations are associated with greater openness to intercountry adoption and women's presence in political decision making is associated with greater restrictiveness.

Conclusion

The findings call into question the effectiveness of the current intercountry adoption regime.
Banking Globalization and Monetary Transmission
Authors: CETORELLI NICOLA , GOLDBERG LINDA S.
Published: September 2012

Globalization of banking raises questions about banks’ liquidity management, their response to liquidity shocks, and the potential for international shock propagation. We conjecture that global banks manage liquidity on a global scale, actively using cross‐border internal funding in response to local shocks. Having global operations insulates banks from changes in monetary policy, while banks without global operations are more affected by monetary policy than previously found. We provide direct evidence that internal capital markets are active in global banks and contribute to the international propagation of shocks. This feature was at play during the financial crisis of 2007–2009.
Regulatory Arbitrage and International Bank Flows
Authors: HOUSTON JOEL F. , LIN CHEN , MA YUE
Published: September 2012

We study whether cross‐country differences in regulations have affected international bank flows. We find strong evidence that banks have transferred funds to markets with fewer regulations. This form of regulatory arbitrage suggests there may be a destructive “race to the bottom” in global regulations, which restricts domestic regulators’ ability to limit bank risk‐taking. However, we also find that the links between regulation differences and bank flows are significantly stronger if the recipient country is a developed country with strong property rights and creditor rights. This suggests that, while differences in regulations have important influences, without a strong institutional environment, lax regulations are not enough to encourage massive capital flows.
Aqueous Route Synthesis of Mesoporous ZrO2 by Agarose Templation
Authors: Ma Xing , Klosterman Luke , Hu Yan‐Yan , Liu Xunpei , Schmidt‐Rohr Klaus , Mallapragada Surya , Akinc Mufit
Published: September 2012

Mesoporous zirconia with high surface area has been synthesized using self‐assembling agarose gel as a template. Agarose gel was formed in the presence of aqueous zirconyl nitrate solutions followed by precipitation of zirconium (hydr)oxide in the gel framework. A porous zirconia structure is obtained by pyrolysis of agarose. Fourier transform infrared spectroscopy is employed to assess the agarose‐zirconia precursor interaction. Changes in the C–O absorption bands indicate zirconium association with the OH groups of the agarose. Solid state 13C NMR studies of the nanocomposite showed a shift in intensity from 70 to 75 ppm indicating conversion of ~7% of C–O–H to C–O–Zr. Scanning electron microscopy reveals that both agarose/zirconia nanocomposite and zirconia have similar morphological features as that of pure agarose gel confirming agarose templation. Phase transformation of zirconia from amorphous to tetragonal between 300°C and 500°C, and gradually into monoclinic phase up to 900°C is observed using X‐ray powder diffraction. Specific surface area and pore size distribution are determined using nitrogen adsorption, employing BET and Barrett–Joyner–Halenda methods, respectively. The specific surface area of porous zirconia after heat treatment at 500°C was determined to be 86 m2/g, which reduced with increasing temperature to 13 m2/g above 900°C. Transmission electron microscopy confirmed the hierarchical structure of porous zirconia.
Defect Healing and Cracking in Ceramic Films During Constrained Sintering
Authors: Li Fan , Pan Jingzhe , Cocks Alan
Published: September 2012

Cracking is a major problem during constrained sintering of ceramic films. A local variation of density in a green film, referred to as a defect in this work, is the leading cause for cracking. This article presents analytical and numerical studies of the behavior of such defects during constrained sintering. An interesting behavior of de‐sintering and healing of the defects is revealed. It is demonstrated that the healing process can be made to start earlier during sintering by using (a) larger particles, (b) lower sintering temperature, and (c) lower initial density. However, a uniform distribution of initial density in the film is shown to be the most effective means to avoid cracking. It is realized that most of the factors beneficial to defect healing are detrimental to sintering a film to high density because the driving force for sintering also drives cracking. The analytical and numerical studies also offer some simple explanations to why thin films are less susceptible to cracking than thick ones. Finally, the constitutive model has been combined with a simple empirical failure criterion, to simulate the initiation and propagation of multiple cracks in a sintering film. The cracking patterns predicted by the simulations resemble those observed during sintering experiments.
Phosphogypsum Transition to α‐Calcium Sulfate Hemihydrate in the Presence of Omongwaite in NaCl Solutions Under Atmospheric Pressure
Authors: Ru Xiaohong , Ma Baoguo , Huang Jian , Huang Yun
Published: September 2012

Preparation of α‐calcium sulfate hemihydrates (α‐HH) from phosphogypsum (PG) under atmospheric pressure has been a promising way to utilize PG. In this study, the phase transition from PG (the main composition is calcium sulfate dihydrate, DH) to α‐HH is investigated in NaCl solutions with different concentrations and reaction temperatures under atmospheric pressure. The results show that the concentration of NaCl affected the phase transition as well as the crystal morphology. Higher reaction temperature above 85°C is found to accelerate the phase‐transition reaction and the products are stable in 18.8 wt% NaCl solution, which is resulted from decreasing water activity with increasing NaCl concentration. The phase‐transition product of PG is a mixture of α‐HH and omongwaite (Na2Ca5(SO4)6·3H2O). Differential scanning calorimeter and thermogravimetry curves and chemical composition, especially Na2O content variation, suggest a third phase, omongwaite is formed during the transition from PG to α‐HH.
Malleability of Gender Role Attitudes and Gendered Messages in Couple and Relationship Education
Authors: Lucier‐Greer Mallory , Ketring Scott A. , Adler‐Baeder Francesca , Smith Thomas
Published: September 2012

Gender role attitudes influence couple functioning and quality. However, few studies have examined within‐person attitudinal change across life events because gender role attitudes are generally considered stable constructs. Emerging research rooted in theory shows evidence of gender role attitude malleability in adulthood. This study examines whether and how couple and relationship education (CRE) influences gender role attitudes. Although CRE is meant to promote relational skill‐building, different CRE curricula appear to contain divergent gendered messages. This study found significant shifts in gender role attitudes reported by participants after engaging in CRE. Some shifts were more egalitarian; other shifts were more traditional. The shifts were based on the curriculum which was either Mastering the Mysteries of Love or Basic Training for Couples. Implications for practice are presented.
Armanni–Ebstein Lesions: A Need for Clarification
Authors: Zhou Chong , Yool Andrea J. , Nolan James , Byard Roger W.
Published: September 2012

Armanni–Ebstein lesions were first described by Luciano Armanni, a pathologist at the University of Naples, during autopsy studies undertaken in 1872, as a unique vacuolar nephropathy associated with poorly controlled diabetes that involves selective renal epithelial cell glycogen accumulation. However, within the last two decades, a broader range of vacuolar changes, including lipid deposition, have also been termed Armanni–Ebstein (AE) lesions, creating some confusion on possible etiology. We would suggest that the term AE phenomenon would be best reserved for the original clear cell change associated with glycogen deposition, and that this should be clearly distinguished from subnuclear lipid vacuolization (“basal vacuolization”). Although there is obvious inter‐relation between these two types of vacuoles, they appear morphologically and biochemically distinct from each other. More precise classification may assist in clarifying the causal processes and possible diagnostic significance of different types of renal epithelial vacuolization at autopsy.
Identification of Human Remains by DNA Analysis of the Gastrointestinal Contents of Fly Larvae
Authors: de Lourdes Chávez‐Briones María , Hernández‐Cortés Raquel , Díaz‐Torres Porfirio , Niderhauser‐García Alberto , Ancer‐Rodríguez Jesús , Jaramillo‐Rangel Gilberto , Ortega‐Martínez Marta
Published: September 2012

Dipterous fly larvae (maggots) are frequently collected from a corpse during a criminal investigation. Previous studies showed that DNA analysis of the gastrointestinal contents of maggots might be used to reveal the identity of a victim. However, this approach has not been used to date in legal investigations, and thus its practical usefulness is unknown. A badly burned body was discovered with its face and neck colonized by fly larvae. Given the condition of the body, identification was not possible. Short tandem repeat (STR) typing was performed using the gastrointestinal contents of maggots collected from the victim and was compared to STR profiles obtained from the alleged father. The probability of paternity was 99.685%. Thus, this comparative DNA test enabled the conclusive identification of the remains. This is the first reported case of analysis of human DNA isolated from the gastrointestinal tract of maggots used to identify a victim in a criminal case.
Invasibility as an emergent property of native metapopulation structure
Authors: Koehncke Arnulf , Telschow Arndt , Kondoh Michio
Published: September 2012

Biological invasions constitute major threats to global biodiversity. Eco‐evolutionary considerations highlight the importance of contemporary evolution in community responses to bioinvasions. However, effects of metapopulation structure on invasion success have been mostly overlooked even though metapopulation structure determines gene flow and is likely to affect evolutionary processes. Here, we investigate a stepping‐stone model with evolving alien native interaction strengths. We demonstrate analytically that the site of invasion can determine the success of an invading consumer because gene flow and demography of a local resource species interact to obstruct local resource adaptation. Our main results are 1) that invasion success is more likely in genetic sink populations of the native species and 2) that invasion is more likely to occur against the migrational flow of native species. These findings suggest that invasibility is best regarded as an emergent property not only of communities but of entire metapopulations. Since migration networks of aliens and natives are often mismatched due to anthropogenic interference, our results indicate how population structure eases the spread of invasives against the migrational flow of natives.
Trophic consequences of a biological invasion: do plant invasions increase predator abundance?
Authors: Lau Jennifer A.
Published: September 2012

As invasive species become integrated into existing communities, they engage in a wide variety of trophic interactions with other community members. Many of these interactions are direct (e.g. predator–prey interactions or interference competition), but invasive species also can affect native community members indirectly, by influencing the abundances of intermediary species in trophic webs. Observational studies suggest that invasive plant species affect herbivorous arthropod communities and that these effects may flow up trophic webs to influence the abundance of predators. However, few studies have experimentally manipulated the presence of invasive plants to quantify the effects of plant invasion on higher trophic levels. Here, I use comparisons across sites that have or have not been invaded by the invasive plant Medicago polymorpha, combined with experimental removals of Medicago and insect herbivores, to investigate how a plant invasion affects the abundance of predators. Both manipulative and observational experiments showed that Medicago increased the abundance of the exotic herbivore Hypera and predatory spiders, suggesting positive bottom–up effects of plant invasions on higher trophic levels. Path analyses conducted on data from natural habitats revealed that Medicago primarily increased spider abundance through herbivore‐mediated indirect pathways. Specifically, Medicago density was positively correlated with the abundance of the dominant herbivore Hypera, and increased Hypera densities were correlated with increased spider abundance. Smaller‐scale experimental studies confirmed that Medicago may increase spider abundance through herbivore‐mediated indirect pathways, but also showed that the effects of Medicago varied across sites, including having no effect or having direct effects on spider abundance. If effects of invasive species commonly flow through trophic webs, then invasive species have the potential to affect numerous species throughout the community, especially those species whose dynamics are tightly connected to highly‐impacted community members through trophic linkages.
Standardization of Vascular Assessment of Erectile Dysfunction
Authors: Sikka Suresh C. , Hellstrom Wayne J.G. , Brock Gerald , Morales Antonio Martin
Published: September 2012

Introduction

In-office evaluation of erectile dysfunction by color duplex Doppler ultrasound (CDDU) may benefit the decision-making process in regard to choosing the most appropriate therapy. Unfortunately, there is no uniform standardization in performing CDDU resulting in high variability in data expression and interpretation when comparing results among various centers, especially when conducting multicenter trials. Establishing standard operating procedures (SOPs) is a major step that will help minimize such variability.

Aim

This SOP describes CDDU procedure with focus on establishing uniformity and normative parameters.

Main Outcome Measure

Measure intra-arterial diameter, peak systolic velocity, end-diastolic velocity, and resistive index for each cavernosal artery.

Methods

After initial discussion with the patient about his history and International Index of Erectile Function evaluation describe procedural steps to the patient. Perform the CDDU in a relaxed state, scanning the entire penis (in B-mode image) using a 7.5- to 12-MHz linear array ultrasound probe. An intracorporal injection of a single or combination of vasoactive agents (e.g., prostaglandin E1, phentolamine, and papaverine) is then administered and CDDU performed at various time points, preferably with audiovisual sexual stimulation (AVSS).

Results

Monitor penile erection response (tumescence and rigidity) near peak blood flow. Self-stimulation or AVSS leaving the patient alone in room or redosing may be considered to decrease any anxiety and help achieve a maximum rigid erection.

Conclusion

Considering the complexity and heterogeneity of CDDU evaluation, this communication will help in standardization and establish uniformity in such data interpretation. When indicated, invasive diagnostic testing involving (i) penile angiography and (ii) cavernosography/cavernosometry to establish veno-occlusive dysfunction may be recommended to facilitate further treatment options.
Standard Operating Procedures for Female Genital Sexual Pain
Authors: Fugl-Meyer Kerstin S. , Bohm-Starke Nina , Damsted Petersen Christina , Fugl-Meyer Axel , Parish Sharon , Giraldi Annamaria
Published: September 2012

Introduction

Female genital sexual pain (GSP) is a common, distressing complaint in women of all ages that is underrecognized and undertreated. Definitions and terminology for female GSP are currently being debated. While some authors have suggested that GSP is not per se a sexual dysfunction, but rather a localized genial pain syndrome, others adhere to using clearly sexually related terms such as dyspareunia and vaginismus.

Aim

The aims of this brief review are to present definitions of the different types of female GSP. Their etiology, incidence, prevalence, and comorbidity with somatic and psychological disorders are highlighted, and different somatic and psychological assessment and treatment modalities are discussed.

Methods

The Standard Operating Procedures (SOP) committee was composed of a chair and five additional experts. No corporate funding or remuneration was received. The authors agreed to survey relevant databases, journal articles and utilize their own clinical experience. Consensus was guided by systematic discussions by e-mail communications.

Main Outcome/Results

There is a clear lack of epidemiological data defining female GSP disorders and a lack of evidence supporting therapeutic interventions. However, this international expert group will recommend guidelines for management of female GSP.

Conclusions

GSP disorders are complex. It is recommended that their evaluation and treatment are performed through comprehensive somato-psychological multidisciplinary approach.
Structural Regulation as Antidote to Complexity Capture
Authors: Weber Robert F.
Published: September 2012

The [structural] approachrejects the idea that some institutions should be allowed to become “too important to fail”. Instead of asking who should perform what regulation, itasks why we regulate banks. It draws a clear distinction between different activities that banks undertake. The banking system provides two crucial services to the rest of the economy: providing companies and households a ready means by which they can make payments for goods and services and intermediating flows of savings to finance investment. Those are the utility aspects of banking where we all have a common interest in ensuring continuity of service.

An accepted principle of system design is to avoid complexity and tight integration of different components or interfaces. Complexity is the enemy of both reliability and security, engineers are fond of saying.The more complex the system, the greater the chance of the unexpected interaction of components, even when they are not faulty in themselves. A truly complex system may be impossible to fully comprehend, and the unexpected interactions may not appear for a very long time … .
Cancer on a mammogram is not memorable: Readers remember their recalls and not cancers
Authors: Pitman Alexander G , Kok Phebe , Zentner Lucila , Taft Rodney , Shnier Darryl , Mercuri Vincenzo , Mehta Kirti , Lawson James , Kremer Sarah , Gledhill Samuel , Cawson Jennifer N
Published: September 2012

Aim

To determine if presence of cancer on a mammogram makes that mammogram more memorable.

Materials and methods

A total of 100 mammograms (25 cancers) were grouped into 5 sets of 20 cases. Set pairs were presented in five reads to eight radiologist readers. Readers were asked to ‘clear’ or ‘call back’ cases, and at post‐baseline reads to indicate whether each case was ‘new’ or ‘old’ (remembered from prior read). Two sets were presented only at baseline, to calculate each reader's false recollection rate. For cases presented more than once (‘old’ cases, 100 presentations) readers could have ‘correct memory’ or ‘memory loss’. Memory performance was defined as odds ratio of correct memory to memory loss.

Multivariate logistic data regression analysis identified predictors of memory performance from: reader, set, time since last read, presence of cancer, and whether the case was called back at the last read.

Results

Memory performance differed markedly between readers and reader identity was a highly significant predictor of memory performance. Presence of cancer was not a significant predictor of memory performance (odds ratio 0.77, 95% CI: 0.49–1.21). Whether the case was called back at the last read was a highly significant predictor (odds ratio 4.22, 95% CI: 2.70–6.61) for the model incorporating reader variability, and also the model without reader variability (odds ratio 2.67, 95% CI: 1.74–4.08).

Conclusion

The only statistically significant predictor of radiologist memory for a mammogram was whether the radiologist ‘called it back’ at a prior reading round. Presence of cancer on a mammogram did not make it memorable.
Strategies for restoration of single implants and use of cross‐pin retained restorations by Australian prosthodontists
Authors: Sambrook RJ , Judge RB , Abuzaar MA
Published: September 2012

Background:  Implant supported restorations (ISRs) for the single implant may be cement retained or screw retained. Limited scientific evidence exists to support the superiority of a retention type for either implant or prosthetic success. The aim of this study was to assess preferences of Australian prosthodontists when restoring single implants. In particular, clinical practices for cross‐pin retained implant supported restorations for a single implant were investigated.

Methods:  A written questionnaire comprised of seven questions, some of which had multiple parts and of both open‐ and closed‐format, was sent to 124 Australian prosthodontists. The questionnaire asked recipients to identify: (1) their preference for retention choice when restoring a single implant; (2) the frequency of use; and (3) clinical practice when restoring a cross‐pin retained restoration.

Results:  Seventy‐seven per cent of respondents indicated that direct to fixture (DTF) retention was their first preference. DTF retention was also the most frequently employed restoration for single implants. Respondents indicated that cross‐pinned ISRs are employed to maintain retrievability or when DTF is not possible. The majority of respondents indicated they always or sometimes use a gasket with cross‐pin retained restorations, though gasket type varied. Thirty‐eight respondents (31%) indicated that they would never use a cross‐pinned retained restoration for a single ISR.

Conclusions:  Australian prosthodontists prefer, and more frequently restore single implants, using DTF retention. Queensland prosthodontists prefer cement retained ISRs. In comparison, cross‐pinned restorations tend to be the least favoured and least used retention type. In addition, variation in opinion exists regarding the need for a gasket and type of gasket to be placed.
Mitigating for Growth: A Blueprint for a Ground Water Exchange Pilot Program in Montana
Authors: Ziemer Laura , Bates Sarah , Casey Meg , Montague Ada
Published: September 2012

Over the last decade, Montana's fastest growing basins have experienced a surge of reliance on a certain “permit‐exempt well loophole,” which enables small ground water diversions to avoid having to go through the regulatory process that determines whether the proposed use would adversely impact senior water users and ground water supply. This loophole has generated significant conflict with senior right owners in areas where exempt wells have provided water for large‐scale residential developments. As a partial solution, this article examines ground water mitigation exchanges designed to address similar issues in Washington and presents the 63rd Montana Legislature with recommendations for a Montana pilot project.
Amino acid analyses of type 3 chondrites Colony, Ornans, Chainpur, and Bishunpur
Authors: CHAN H.‐S. , MARTINS Zita , SEPHTON Mark A.
Published: September 2012

Abstract– The CO3s Colony and Ornans and LL3s Chainpur and Bishunpur were analyzed for the first time for amino acids using gas chromatography–mass spectrometry (GC‐MS). Type 3 chondrites have relatively unaltered metamorphic and petrological histories. Chainpur was the most amino acid rich of the four type 3 chondrites with a total amino acid abundance of 3330 parts per billion (ppb). The other type 3 chondrites had total amino acid abundances that ranged from 660 to 1110 ppb. A d/l ratio of <0.7 for all proteic amino acids suggests at least some amino acid terrestrial contamination. However, a small fraction of indigenous extraterrestrial amino acids cannot be excluded because of the presence of the nonprotein amino acid α‐aminoisobutyric acid (α‐AIB), and unusually high relative abundances (to glycine) of β‐alanine and γ‐ABA. The comparisons between the free and total amino acid contents of the samples also indicate a low free/total amino acid ratio (ranging from about 1:4 in CO chondrites to about 1:50 in Chainpur), which indicate that amino acids are present mainly in the bound form and were made detectable after acid hydrolysis.
Pulmonary Vein Isolation Supported by MRI‐Derived 3D‐Augmented Biplane Fluoroscopy: A Feasibility Study and a Quantitative Analysis of the Accuracy of the Technique
Authors: BOURIER FELIX , VUKAJLOVIC DEJAN , BROST ALEXANDER , HORNEGGER JOACHIM , STROBEL NORBERT , KURZIDIM KLAUS
Published: September 2012

MRI‐Derived 3D‐Augmented Biplane Fluoroscopy. Background: Despite the advancement of technology in electroanatomic mapping systems (EAMS), fluoroscopy remains a necessary, basic imaging modality for electrophysiology procedures. We present a feasibility study of new software that enables 3D‐augmented fluoroscopy in biplane catheterization laboratories for planning and guidance of pulmonary vein isolation (PVI). The computer‐assisted overlay registration accuracy was assessed in a clinical setting using an automatic calculation of overlay projection geometry that was derived from hardware sensors in C‐arms, detectors, and patient table.

Methods: Consecutive patients (n = 89) underwent left atrium (LA) magnetic resonance imaging MRI scan prior to PVI. Ideal ablation lines encircling the ipsilateral pulmonary veins (PVs) at antral level were drawn onto the segmented LA surface. The 3D‐model was superimposed onto biplane fluoroscopy and matched with angiographies of LA and PVs. Three‐dimensional‐overlay projection geometry was automatically calculated from C‐arm, detectors, and table sensors. Accuracy of technique was assessed as alignment of MRI‐derived 3D overlay and angiographic LA/PV anatomy. Integrity of registered overlay was quantified using landmark measurements.

Results: Alignment offsets were 1.3 ± 1.5 mm in left PV, 1.2 ± 1.5 mm in right PV, and 1.1 ± 1.4 mm in LA roof region. Bravais–Pearson correlation of the landmark measurements was r = 0.978 (s  < 0.01), mean offset between landmark distance measurements was 1.4 ± 0.78 mm. Average time needed for overlay registration was 9.5 ± 3.5 seconds.

Conclusions: MRI‐derived 3D‐augmented fluoroscopy demonstrated a high level of accuracy when compared with LA/PV angiography. The new system could be especially useful to guide procedures not supported by EAMS, such as cryotechnique PVI. (J Cardiovasc Electrophysiol, Vol. 24, pp. 113‐120, February 2013)
Changes in Aortic Pulse Wave Velocity in Hypertensive Postmenopausal Women: Comparison Between a Calcium Channel Blocker vs Angiotensin Receptor Blocker Regimen
Authors: Hayoz Daniel , Zappe Dion H. , Meyer Marie A.R. , Baek InYoung , Kandra Albert , Joly Marie P. , Mazzolai Lucia , Haesler Erik , Periard Daniel
Published: September 2012

J Clin Hypertens (Greenwich). 2012;14:773–778. ©2012 Wiley Periodicals, Inc.

Postmenopausal women are at greater risk for hypertension‐related cardiovascular disease. Antihypertensive therapy may help alleviate arterial stiffness that represents a potential modifiable risk factor of hypertension. This randomized controlled study investigated the difference between an angiotensin receptor blocker and a calcium channel blocker in reducing arterial stiffness. Overall, 125 postmenopausal hypertensive women (age, 61.4±6 years; systolic blood pressure/diastolic blood pressure [SBP/DBP], 158±11/92±9 mm Hg) were randomized to valsartan 320 mg±hydrochlorothiazide (HCTZ) (n=63) or amlodipine 10 mg±HCTZ (n=62). The primary outcome was carotid‐to‐femoral pulse wave velocity (PWV) changes after 38 weeks of treatment. Both treatments lowered peripheral blood pressure (BP) (−22.9/−10.9 mm Hg for valsartan and −25.2/−11.7 mm Hg for amlodipine, P=not significant) and central BP (−15.7/−7.6 mm Hg for valsartan and −19.2/−10.3 mm Hg for amlodipine, P<.05 for central DBP). Both treatments similarly reduced the carotid‐femoral PWV (−1.9 vs −1.7 m/s; P=not significant). Amlodipine was associated with a higher incidence of peripheral edema compared with the valsartan group (77% vs 14%, P<.001). BP lowering in postmenopausal women led to a reduction in arterial stiffness as assessed by PWV measurement. Both regimens reduced PWV to a similar degree after 38 weeks of treatment despite differences in central BP lowering, suggesting that the effect of valsartan on PWV is mediated through nonhemodynamic effects.
Visceral pain readouts in experimental medicine
Authors: Blackshaw L. A.
Published: September 2012

Visceral pain is studied at the level of the primary afferent fiber, spinal cord, subcortical, and cortical levels electrophysiologically and using brain imaging, which provides an objective measure of excitation at each level. However, correlation of these with actual perception of pain in conscious animal models has been problematic, and we rely on indirect measures in most preclinical research. The main method is electromyographic recording of abdominal muscle contractions in response to colorectal distension (CRD), which may reflect reflexes set up at several levels of the above pathway. Several experimental treatments for visceral pain have failed in clinical trials, possibly because of failure to translate from preclinical observations on CRD responses in animals to perception of spontaneous events in patients. Therefore, we need more objective outcomes. In this NGM issue, Hultin et al. show feasibility of routine recordings of cortical evoked electrical potentials (CEP) using implanted cranial electrodes in response to graded CRD in rats. CEP comprised three temporal components with latencies of approximately 20–50 ms, 90–180 ms, and 300 ms, which were reproducible and graded in intensity and latency with distension pressure. From this basic study it is clear that colorectal evoked potentials can be recorded reliably in awake rats and may serve as an objective marker for centrally projecting visceral sensory signals in rodents. It remains to be seen how these responses are affected by drugs under development for clinical management of visceral pain, and if there is improved translation.
Unsteady Aerodynamics of a Low Aspect Ratio Turbine Stage: Modeling Issues and Flow Physics
Authors: Persico G. , Mora A. , Gaetani P. , Savini M.
Published: September 2012

In this paper the three-dimensional unsteady aerodynamics of a low aspect ratio, high pressure turbine stage are studied. In particular, the results of fully unsteady three-dimensional numerical simulations, performed with ANSYS-CFX, are critically evaluated against experimental data. Measurements were carried out with a novel three-dimensional fast-response pressure probe in the closed-loop test rig of the Laboratorio di Fluidodinamica delle Macchine of the Politecnico di Milano. An analysis is first reported about the strategy to limit the CPU and memory requirements while performing three-dimensional simulations of blade row interaction when the rotor and stator blade numbers are prime to each other. What emerges as the best choice is to simulate the unsteady behavior of the rotor alone by applying the stator outlet flow field as a rotating inlet boundary condition (scaled on the rotor blade pitch). Thanks to the reliability of the numerical model, a detailed analysis of the physical mechanisms acting inside the rotor channel is performed. Two operating conditions at different vane incidence are considered, in a configuration where the effects of the vortex-blade interaction are highlighted. Different vane incidence angles lead to different size, position, and strength of secondary vortices coming out from the stator, thus promoting different interaction processes in the subsequent rotor channel. However some general trends can be recognized in the vortex-blade interaction: the sense of rotation and the spanwise position of the incoming vortices play a crucial role on the dynamics of the rotor vortices, determining both the time-mean and the time-resolved characteristics of the secondary field at the exit of the stage.
An Advanced Multiconfiguration Stator Well Cooling Test Facility
Authors: Coren D. D. , Atkins N. R. , Turner J. R. , Eastwood D. E. , Davies S. , Child P. R. N. , Dixon J. A. , Scanlon T. J.
Published: September 2012

Optimization of cooling systems within gas turbine engines is of great interest to engine manufacturers seeking gains in performance, efficiency, and component life. The effectiveness of coolant delivery is governed by complex flows within the stator wells and the interaction of main annulus and cooling air in the vicinity of the rim seals. This paper reports on the development of a test facility which allows the interaction of cooling air and main gas paths to be measured at conditions representative of those found in modern gas turbine engines. The test facility features a two stage turbine with an overall pressure ratio of approximately 2.6:1. Hot air is supplied to the main annulus using a Rolls-Royce PLC Dart compressor driven by an aero-derivative engine plant. Cooling air can be delivered to the stator wells at multiple locations and at a range of flow rates which cover bulk ingestion through to bulk egress. The facility has been designed with adaptable geometry to enable rapid changes of cooling air path configuration. The coolant delivery system allows swift and accurate changes to the flow settings such that thermal transients may be performed. Particular attention has been focused on obtaining high accuracy data, using a radio telemetry system, as well as thorough through-calibration practices. Temperature measurements can now be made on both rotating and stationary disks with a long term uncertainty in the region of 0.3 K. A gas concentration measurement system has also been developed to obtain direct measurement of re-ingestion and rim seal exchange flows. High resolution displacement sensors have been installed in order to measure hot running geometry. This paper documents the commissioning of a test facility which is unique in terms of rapid configuration changes, nondimensional engine matching, and the instrumentation density and resolution. Example data for each of the measurement systems are presented. This includes the effect of coolant flow rate on the metal temperatures within the upstream cavity of the turbine stator well, the axial displacement of the rotor assembly during a commissioning test, and the effect of coolant flow rate on mixing in the downstream cavity of the stator well.
Laser speckle contrast imaging: Multifractal analysis of data recorded in healthy subjects
Authors: Humeau‐Heurtier Anne , Mahé Guillaume , Durand Sylvain , Henrion Daniel , Abraham Pierre
Published: September 2012

Purpose:

The monitoring of microvascular blood flow can now be performed with laser speckle contrast imaging (LSCI), a new noninvasive laser‐based technique. LSCI images have good spatial and temporal resolutions. Nevertheless, from now, few processing of these data have been performed to have a better knowledge on their properties. We herein propose a multifractal analysis of LSCI data recorded in the forearm of healthy subjects, based on the method from Halseyet al., one of the popular methods using the box‐counting technique.

Methods:

In laser speckle contrast image time sequences, we studied time evolution of pixel values, as well as time evolution of pixel values averaged in regions of interest (ROI) of different sizes. The results are compared with the ones obtained with single‐point laser Doppler flowmetry (LDF) signals recorded simultaneously to LSCI images.

Results:

Our work shows that, for the range of scales studied and with the method from Halseyet al., time evolution of pixel values present narrow multifractal spectra, reminding the ones of monofractal data. However, we observe that when LSCI pixel values are averaged in ROI large enough and followed with time, the multifractal spectra become larger and closer to the ones of LDF signals.

Conclusions:

Single pixels from laser speckle contrast images may not possess the same multifractal properties as LDF signals. These findings could now be compared with the ones obtained with other ranges of scales and with data recorded from pathological subjects.
Segmentation of malignant gliomas through remote collaboration and statistical fusion
Authors: Xu Zhoubing , Asman Andrew J. , Singh Eesha , Chambless Lola , Thompson Reid , Landman Bennett A.
Published: September 2012

Purpose:

Malignant gliomas represent an aggressive class of central nervous system neoplasms. Correlation of interventional outcomes with tumor morphometry data necessitates 3D segmentation of tumors (typically based on magnetic resonance imaging). Expert delineation is the long‐held gold standard for tumor segmentation, but is exceptionally resource intensive and subject to intrarater and inter‐rater variability. Automated tumor segmentation algorithms have been demonstrated for a variety of imaging modalities and tumor phenotypes, but translation of these methods across clinical study designs is problematic given variation in image acquisition, tumor characteristics, segmentation objectives, and validation criteria. Herein, the authors demonstrate an alternative approach for high‐throughput tumor segmentation using Internet‐based, collaborative labeling.

Methods:

In a study of 85 human raters and 98 tumor patients, raters were recruited from a general university campus population (i.e., no specific medical knowledge), given minimal training, and provided web‐based tools to label MRI images based on 2D cross sections. The labeling goal was characterized as to extract the enhanced tumor cores on T1‐weighted MRI and the bright abnormality on T2‐weighted MRI. An experienced rater manually constructed the ground truth volumes of a randomly sampled subcohort of 48 tumor subjects (for both T1w and T2w). Raters’ taskwise individual observations, as well as the volumewise truth estimates via statistical fusion method, were evaluated over the subjects having the ground truth.

Results:

Individual raters were able to reliably characterize (with >0.8 dice similarity coefficient, DSC) the gadolinium‐enhancing cores and extent of the edematous areas only slightly more than half of the time. Yet, human raters were efficient in terms of providing these highly variable segmentations (less than 20 s per slice). When statistical fusion was used to combine the results of seven raters per slice for all slices in the datasets, the 3D agreement of the fused results with expertly delineated segmentations was on par with the inter‐rater reliability observed between experienced raters using traditional 3D tools (approximately 0.85 DSC). The cumulative time spent per tumor patient with the collaborative approach was equivalent to that with an experienced rater, but the collaborative approach could be achieved with less training time, fewer resources, and efficient parallelization.

Conclusions:

Hence, collaborative labeling is a promising technique with potentially wide applicability to cost‐effective manual labeling of medical images.
Changing the Order of Newton's Laws—Why & How the Third Law Should be First
Authors: Stocklmayer Sue , Rayner John P. , Gore Michael M.
Published: September 2012

Newton's laws are difficult both for teachers and students at all levels.1–3 This is still the case despite a long history of critique of the laws as presented in the classroom. For example, more than 50 years ago Eisenbud4 and Weinstock5 proposed reformulations of the laws that put them on a sounder, more logically consistent base than is presented in many textbooks without resorting to “intuitional or anthropomorphic contrivances.”5 In 1990, Arnold Arons6 wrote that “the Law of Inertia and the concept of force have, historically, been two of the most formidable stumbling blocks for students.” One might imagine, therefore, that by 2012 remedial strategies would have resolved these difficulties, but there is little evidence that the problem has been satisfactorily addressed. Diagnostic tools such as the Force Concept Inventory7,8 have cast light on areas of difficulty; remedial strategies have included historical approaches, computer simulations, analogical approaches, and many more.9–12 Nevertheless, papers on the subject are still being published.8,9,11–13 Textbook descriptions of the laws have also contributed to the problem: in general the topic is presented with little discussion and the third law in particular is often given cursory treatment. This paper addresses the introduction of the laws in the classroom, especially the order in which they are customarily presented, and discusses particular issues attached to the third law that constitute major impediments to understanding.14–16 We have devised a six-hour workshop, for middle-school teachers and senior students, that has achieved some success in enhancing understanding of Newton's laws by adopting a different order of presentation of the laws from that traditionally given in physics texts. Our approach is deliberately intuitional and experiential, as we believe the ideas need to be felt or owned by students before introducing them to a more rigorous formalism.
An inexpensive, multipurpose physical pendulum
Authors: Schultz David
Published: September 2012

The pendulum is a highly versatile tool for teaching physics. Many special purpose pendula for student experiments have been described.1–4 In this paper, I describe an inexpensive, multipurpose physical pendulum that can function as both a variable gravity and ballistic pendulum. I designed the apparatus for use in a rotational dynamics unit of the AP Physics C mechanics course. The use of a bike wheel hub pivot allows for low-friction, rugged operation that yields results commensurate with those obtained with much more expensive pendula available on the market (typically $500 per unit5), placing these types of experiments within reach of the teacher on a restricted budget.