bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanical properties of polypropylene (PP) + high‐density polyethylene (HDPE) binary blends: Non‐isothermal degradation kinetics of PP + HDPE (80/20) Blends
Authors: Şirin Kamil , Doğan Fatih , Çanlı Murat , Yavuz Mesut
Published: May 2013

In this study, the mechanical properties and non‐isothermal degradation kinetics of polypropylene (PP), high‐density polyethylene (HDPE) with dilauroyl peroxide and their blends in different mixture ratios were investigated. The effects of adding dilauroyl peroxide (0–0.20 wt%) on the mechanical and thermal properties of PP + HDPE blends have been studied. On the other hand, the kinetics of the thermal degradation and thermal oxidative degradation of PP + HDPE (80/20 wt%) blends were studied in different atmospheres, to analyze their thermal stability. The kinetic and thermodynamic parameters such as the activation energy, Ea, the pre‐exponential factor, A, the reaction order, n, the entropy change, the enthalpy change, and the free energies of activated complex related to PP, HDPE, and blend systems were calculated by means of the several methods on the basis of the single heating rate. A computer program was developed for automatically processing the data to estimate the reaction parameters by using different models. Most appropriate method was determined for each decomposition step according to the least‐squares linear regression. Copyright © 2013 John Wiley & Sons, Ltd.
Novel ethylene/norbornene copolymers as nonreleasing antioxidants for food‐contact polyolefinic materials
Authors: Stagnaro Paola , Mancini Giorgio , Piccinini Achille , Losio Simona , Sacchi Maria Carmela , Viglianisi Caterina , Menichetti Stefano , Adobati Alessandro , Limbo Sara
Published: May 2013

An efficient procedure for the copolymerization of ethylene (E) with a novel norbornenic comonomer (NArOH) bearing a stabilizing moiety analogous to commercial antioxidant 2,6‐di‐tert‐butyl‐4‐methylphenol (BHT) is successfully developed. This study is aimed at: i) tuning the concentration of the stabilizing function along the polymer chain, and ii) preparing “nonreleasing” polymeric additives specifically destined to protect commercial low‐density polyethylene (LDPE). Films obtained from blends of the novel E/NArOH copolymers with an antioxidant‐free LDPE matrix are characterized by superior thermal, thermo‐oxidative, and photostability when compared not only with neat LDPE films but also with films stabilized by the commercial BHT additive. Specific migration tests conducted in order to investigate the nonreleasing character of the novel macromolecular additives confirm the reduced risk of migration, from the films into food simulants, of unreacted comonomer or degradation products bearing the antioxidant moiety. © 2013 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013, 51, 1007–1016
Can delayed time to referral to a tertiary level urologist with an abnormal PSA level affect subsequent gleason grade in the opportunistically screened population?
Authors: O'Kelly Fardod , Thomas Arun , Murray Denise , Galvin David , Mulvin David , Quinlan David M.
Published: May 2013

PURPOSE

There is growing conflict in the literature describing the effect of delayed treatment on outcomes following radical prostatectomy. There is also evidence to suggest progression of low‐risk prostate cancer to develop higher grades and volumes of prostate cancer during active surveillance. It is unknown as to what affect a delay in referral of those men with abnormal screened‐PSA levels have on subsequent Gleason grade.

METHODS

We identified 350 men through our rapid access prostate clinic who underwent TRUS biopsy for abnormal age‐related PSA and/or abnormal clinical examination. Clinicopathological findings were compared for those with positive versus negative TRUS biopsies, and for those with initial delays in referral (<12 months, 12–18 months, and >18 months). We used ANOVA and Student's t‐tests amongst other statistical tools to examine significance of clinical findings.

RESULTS

Of the 350 men who underwent TRUS biopsy, those with a delay in referral of 12 months or more were significantly associated with higher PSA titers, clinically palpable disease and likelihood of diagnosis with prostate cancer. A delay of 18 months or more led to a significantly higher risk of being diagnosed with a leading grade 4 prostate cancer, which was further supported using PSA velocity as a diagnostic tool (change >0.4 ng/ml/year).

CONCLUSION

We recommend that repeated asymptomatic abnormal age‐related PSA readings and/or abnormal clinical examination in the screened population be referred without delay to a urologist for further assessment, enrolment into an active surveillance program or definitive subsequent treatment. Prostate 73:1263–1269, 2013. © 2013 Wiley Periodicals, Inc.
Photoluminescence thermometry with alkyl‐terminated silicon nanoparticles dispersed in low‐polar liquids
Authors: Ryabchikov Yury V. , Alekseev Sergei , Lysenko Vladimir , Bremond Georges , Bluet Jean‐Marie
Published: May 2013

Steady‐state and time‐resolved photoluminescence of silicon nanoparticles dispersed in low‐polar liquids at above room temperature is studied. The roles of low‐polar liquids as well as mechanisms responsible for their temperature‐dependent photoluminescence are discussed. The thermal sensitivity of the photoluminescence is estimated and application of the nanoparticles as nanothermometers is proposed.

magnified image

(© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
C2Detector: a covert channel detection framework in cloud computing
Authors: Wu Jingzheng , Ding Liping , Wu Yanjun , Min‐Allah Nasro , Khan Samee U. , Wang Yongji
Published: May 2013

Cloud computing is becoming increasingly popular because of the dynamic deployment of computing service. Another advantage of cloud is that data confidentiality is protected by the cloud provider with the virtualization technology. However, a covert channel can break the isolation of the virtualization platform and leak confidential information without letting it known by virtual machines. In this paper, the threat model of covert channels is analyzed. The channels are classified into three categories, and only the category that is new to cloud computing is concerned, for example, CPU load‐based, cache‐based, and shared memory‐based covert channels. The covert channel scenario is modeled into an error‐corrected four‐state automaton, and two error‐corrected algorithms are designed. A new detection framework termed C2Detector is presented. C2Detector includes a captor located in the hypervisor and a two‐phase synthesis algorithm implemented as Markov and Bayesian detectors. A prototype of C2Detector is implemented on Xen hypervisor, and its performance of detecting the covert channels is demonstrated. The experiment results show that C2Detector can detect the three types of the covert channels with an acceptable false positive rate by using a pessimistic threshold. Moreover, C2Detector is a plug‐in framework and can be easily extended. It is believed that new covert channels can be detected by C2Detector in the future. Copyright © 2013 John Wiley & Sons, Ltd.
AK‐nearest neighbors survival probability prediction method
Authors: Lowsky D.J. , Ding Y. , Lee D.K.K. , McCulloch C.E. , Ross L.F. , Thistlethwaite J.R. , Zenios S.A.
Published: May 2013

We introduce a nonparametric survival prediction method for right‐censored data. The method generates a survival curve prediction by constructing a (weighted) Kaplan–Meier estimator using the outcomes of theKmost similar training observations. Each observation has an associated set of covariates, and a metric on the covariate space is used to measure similarity between observations. We apply our method to a kidney transplantation data set to generate patient‐specific distributions of graft survival and to a simulated data set in which the proportional hazards assumption is explicitly violated. We compare the performance of our method with the standard Cox model and the random survival forests method. Copyright © 2012 John Wiley & Sons, Ltd.
Transdermal Delivery Devices: Fabrication, Mechanics and Drug Release from Silk
Authors: Raja Waseem K. , MacCorkle Scott , Diwan Izzuddin M. , Abdurrob Abdurrahman , Lu Jessica , Omenetto Fiorenzo G. , Kaplan David L.
Published: May 2013

Microneedles are a relatively simple, minimally invasive and painless approach to deliver drugs across the skin. However, there remain limitations with this approach because of the materials most commonly utilized for such systems. Silk protein, with tunable and biocompatibility properties, is a useful biomaterial to overcome the current limitations with microneedles. Silk devices preserve drug activity, offer superior mechanical properties and biocompatibility, can be tuned for biodegradability, and can be processed under aqueous, benign conditions. In the present work, the fabrication of dense microneedle arrays from silk with different drug release kinetics is reported. The mechanical properties of the microneedle patches are tuned by post‐fabrication treatments or by loading the needles with silk microparticles, to increase capacity and mechanical strength. Drug release is further enhanced by the encapsulation of the drugs in the silk matrix and coating with a thin dissolvable drug layer. The microneedles are used on human cadaver skin and drugs are delivered successfully. The various attributes demonstrated suggest that silk‐based microneedle devices can provide significant benefit as a platform material for transdermal drug delivery.
Checked coverage: an indicator for oracle quality
Authors: Schuler David , Zeller Andreas
Published: May 2013

A known problem of traditional coverage metrics is that they do not assess oracle quality—that is, whether the computation result is actually checked against expectations. In this paper, we introduce the concept of checked coverage—the dynamic slice of covered statements that actually influence an oracle. Our experiments on seven open‐source projects show that checked coverage is a sure indicator for oracle quality and even more sensitive than mutation testing. Copyright © 2013 John Wiley & Sons, Ltd.
Situated cognition
Authors: Roth Wolff‐Michael , Jornet Alfredo
Published: May 2013

Following the cognitive revolution, when knowing and learning have come to be theorized in terms of representations stored and processed in the mind, empirical and theoretical developments in very different scholarly disciplines have led to the emergence of the situated cognition hypothesis, which consists of a set of interlocking theses: cognition is embodied, fundamentally social, distributed, enacted, and often works without representations. We trace the historical origins of this hypothesis and discuss the evidential support this hypothesis receives from empirical and modeling studies. We distinguish the question of where cognition is located from the question of what cognition is, because the confounding of the two questions leads to misunderstandings in the sometimes‐ardent debates concerning the situated cognition hypothesis. We conclude with recommendations for interdisciplinary approaches to the nature of cognition. WIREs Cogn Sci 2013, 4:463–478. doi: 10.1002/wcs.1242

This article is categorized under:

Psychology > Theory and Methods
Pitfalls and improvements in the joint inference of heteroscedasticity and autocorrelation in hydrological model calibration
Authors: Evin Guillaume , Kavetski Dmitri , Thyer Mark , Kuczera George
Published: May 2013

Residual errors of hydrological models are usually both heteroscedastic and autocorrelated. However, only a few studies have attempted to explicitly include these two statistical properties into the residual error model and jointly infer them with the hydrological model parameters. This technical note shows that applying autoregressive error models to raw heteroscedastic residuals, as done in some recent studies, can lead to unstable error models with poor predictive performance. This instability can be avoided by applying the autoregressive process to standardized residuals. The theoretical analysis is supported by empirical findings in three hydrologically distinct catchments. The case studies also highlight strong interactions between the parameters of autoregressive residual error models and the water balance parameters of the hydrological model.
Perturbations of RNA helicases in cancer
Authors: Robert Francis , Pelletier Jerry
Published: May 2013

Helicases are implicated in most stages of the gene expression pathway, ranging from DNA replication, RNA transcription, splicing, RNA transport, ribosome biogenesis, mRNA translation, RNA storage and decay. These enzymes utilize energy derived from nucleotide triphosphate hydrolysis to remodel ribonucleoprotein complexes, RNA, or DNA and in this manner affect the information content or output of RNA. Several RNA helicases have been implicated in the oncogenic process—either through altered expression levels, mutations, or due to their role in pathways required for tumor initiation, progression, maintenance, or chemosensitivity. The purpose of this review is to highlight those RNA helicases for which there is significant evidence implicating them in cancer biology.WIREs RNA2013, 4:333–349. doi: 10.1002/wrna.1163

This article is categorized under:

RNA in Disease and Development > RNA in Disease

Regulatory RNAs/RNAi/Riboswitches > Biogenesis of Effector Small RNAs
Fermentative and growth performances of Dekkera bruxellensis in different batch systems and the effect of initial low cell counts in co‐cultures with Saccharomyces cerevisiae
Authors: Meneghin Maria Cristina , Bassi Ana Paula Guarnieri , Codato Carolina Brito , Reis Vanda Renata , Ceccato‐Antonini Sandra Regina
Published: May 2013

Dekkera bruxellensis is a multifaceted yeast present in the fermentative processes used for alcoholic beverage and fuel alcohol production – in the latter, normally regarded as a contaminant. We evaluated the fermentation and growth performance of a strain isolated from water in an alcohol‐producing unit, in batch systems with/without cell recycling in pure and co‐cultures with Saccharomyces cerevisiae. The ethanol resistance and aeration dependence for ethanol/acid production were verified. Ethanol had an effect on the growth of D. bruxellensis in that it lowered or inhibited growth depending on the concentration. Acid production was verified in agitated cultures either with glucose or sucrose, but more ethanol was produced with glucose in agitated cultures. Regardless of the batch system, low sugar consumption and alcohol production and expressive growth were found with D. bruxellensis. Despite a similar ethanol yield compared to S. cerevisiae in the batch system without cell recycling, ethanol productivity was approximately four times lower. However, with cell recycling, ethanol yield was almost half that of S. cerevisiae. At initial low cell counts of D. bruxellensis (10 and 1000 cells/ml) in co‐cultures with S. cerevisiae, a decrease in fermentative efficiency and a substantial growth throughout the fermentative cycles were displayed by D. bruxellensis. Due to the peculiarity of cell repitching in Brazilian fermentation processes, D. bruxellensis is able to establish itself in the process, even when present in low numbers initially, substantially impairing bioethanol production due to the low ethanol productivity, in spite of comparable ethanol yields. Copyright © 2013 John Wiley & Sons, Ltd.
Phenomenology of QCD threshold resummation for gluino pair production at NNLL
Authors: Pfoh Torsten
Published: May 2013

Abstract

We examine the impact of threshold resummation for the inclusive hadronic production cross section of gluino pairs at next-to-next-to-leading-logarithmic accuracy, compared to the exact next-to-leading-order cross section and the next-to-next-to-leading-order approximation. Here, we apply formulas derived recently in the classical Mellin-space formalism. Moreover, we give the analytic input for the alternative momentum-space formalism and discuss the crucial points of the numeric implementation. We find that soft resummation keeps the hadronic cross section close to the fixed next-to-leading-order result.
Therapeutic Approach to Patients With a Lower‐Pitched Voice After Thyroidectomy
Authors: Nam Inn‐Chul , Bae Ja‐Sung , Chae Byung‐Joo , Shim Mi‐Ran , Hwang Yeon‐Shin , Sun Dong‐Il
Published: May 2013

Background

A lower‐pitched voice is one of the most common voice alterations after thyroidectomy without laryngeal nerve injury. The aim of this study was to evaluate the acoustic and stroboscopic changes and the treatment outcomes in patients with a lower‐pitched voice with the goal of eventually establishing a therapeutic guideline.

Methods

Patients with a lower‐pitched voice were selected according to the results of acoustic analysis among thyroidectomized patients. According to their pitch‐gliding ability, patients were classified into a “gliding group” and “nongliding group,” and direct voice therapy was performed. For those who did not respond, indirect voice therapy with subsequent identical direct voice therapy was performed. Video‐stroboscopy, acoustic and perceptual analysis, and subjective analysis using a questionnaire were performed before and after treatment. The results of the two groups were compared.

Results

Fifty patients were enrolled. Decreased vocal cord tension was the most common stroboscopic finding in these patients. After direct voice therapy, 87 % of patients in the gliding group showed restoration of pitch 2 months after thyroidectomy. None of the patients in the nongliding group showed improvement. After indirect voice therapy and subsequent direct voice therapy, these nonresponders finally showed improvement 4.5 months after thyroidectomy. Several characteristic stroboscopic findings of the nongliding group were identified.

Conclusions

The pitch‐gliding ability and several specific stroboscopic findings were predictive of a response to direct voice therapy. Based on these findings, an individualized therapeutic approach could be applied, and the pitch of patients with a lower‐pitched voice after thyroidectomy was restored earlier than expected.
Streptomycin resistance-aided genome shuffling to improve doramectin productivity of Streptomyces avermitilis NEAU1069
Authors: Zhang Ji , Wang Xiangjing , Diao Jinna , He Hairong , Zhang Yuejing , Xiang Wensheng
Published: May 2013

Genome shuffling is an efficient approach for the rapid engineering of microbial strains with desirable industrial phenotypes. In this study, a strategy of incorporating streptomycin resistance screening into genome shuffling (GS-SR) was applied for rapid improvement of doramectin production by Streptomyces avermitilis NEAU1069. The starting mutant population was generated through treatment of the spores with N-methyl-N’-nitro-N-nitrosoguanidine and ultraviolet (UV) irradiation, respectively, and five mutants with higher productivity of doramectin were selected as starting strains for GS-SR. Finally, a genetically stable strain F4-137 was obtained and characterized to be able to yield 992 ± 4.4 mg/l doramectin in a shake flask, which was 7.3-fold and 11.2-fold higher than that of the starting strain UV-45 and initial strain NEAU1069, respectively. The doramectin yield by F4-137 in a 50-l fermentor reached 930.3 ± 3.8 mg/l. Furthermore, the factors associated with the improved doramectin yield were investigated and the results suggested that mutations in ribosomal protein S12 and the enhanced production of cyclohexanecarboxylic coenzyme A may contribute to the improved performance of the shuffled strains. The random amplified polymorphic DNA analysis showed a genetic diversity among the shuffled strains, which confirmed the occurrence of genome shuffling. In conclusion, our results demonstrated that GS-SR is a powerful method for enhancing the production of secondary metabolites in Streptomyces.
Return to Being Black, Living in the Red: A Race Gap in Wealth That Goes Beyond Social Origins
Authors: Killewald Alexandra
Published: May 2013

In the United States, racial disparities in wealth are vast, yet their causes are only partially understood. In Being Black, Living in the Red, Conley (1999) argued that the sociodemographic traits of young blacks and their parents, particularly parental wealth, wholly explain their wealth disadvantage. Using data from the 1980–2009 waves of the Panel Study of Income Dynamics, I show that this conclusion hinges on the specific sample considered and the treatment of debtors in the sample. I further document that prior research has paid insufficient attention to the possibility of variation in the association between wealth and race at different points of the net worth distribution. Among wealth holders, blacks remain significantly disadvantaged in assets compared with otherwise similar whites. Among debtors, however, young whites hold more debt than otherwise similar blacks. The results suggest that, among young adults, debt may reflect increased access to credit, not simply the absence of assets. The asset disadvantage for black net wealth holders also indicates that research and policy attention should not be focused only on young blacks “living in the red.”
Missing Minorities? The Phases of IRCA Legislation and Relative Net Undercounts of the 1990 vis-à-vis 2000 Decennial Census for Foreign-born Cohorts
Authors: Kaneshiro Matheu
Published: May 2013

The quality of the decennial census of the United States is compromised by population undercount, which often misses immigrants and racial/ethnic minorities, thereby diminishing federal resources allocated to such groups. Using a modified version of demographic analysis and informed by the latest contributions of emigration scholarship, this research estimates net undercount for the 1990 census relative to the 2000 census by age, sex, year-of-entry, and place-of-birth cohorts. Ordinary least squares estimates suggest that males, recent arrivals, and cohorts aged 15–44 had higher relative net undercount for 1990 compared with 2000. Much higher relative net undercount was found for cohorts from Africa, Latin America, and the Caribbean (excluding Cuba and Puerto Rico) who were ineligible for amnesty under the Immigration Reform and Control Act of 1986 (i.e., those fitting the profile of an undocumented immigrant). Larger implications of these findings suggest that the political climate in which a person is embedded—particularly for persons who may feel threatened or marginalized by the government and/or the public—affects that person’s willingness to respond to the census.
Selling Italy by the sound: cross-cultural interchanges through cover records
Authors: PRATO PAOLO
Published: May 2013

Since the beginning of modern canzone, cover versions have represented a shortcut to importing and exporting songs across national borders. By breaking language barriers, these records have played the role of ambassadors of Italian music abroad and, vice-versa, of Anglo-American music at home. Although cover records mania boomed especially in the 1960s, the history of Italian popular music is disseminated by such examples, including exchanges with French- and Spanish-speaking countries as well. After reflecting on the nature of ‘cover’ and offering a definition that includes its being a cross-cultural space most typical of Italy and other peripheral countries in the age of early contact with pop modernity, the paper focuses on the economic, aesthetic and sociological paradigms that affect the international circulation of cover records and suggests a few theoretical explanations that refuse the obsolete ‘cultural imperialism’ thesis in favour of a more flexible view hinged upon the notion of ‘deterritorialisation’. In the final section the paper provides a short history of Italian records that were hits abroad, decade by decade, and ends by highlighting those artists that played the role of cultural mediators between Italy and the world.
‘I would like to sound like Heidi Klum’: What do non-native speakers say about who they want to sound like?
Authors: Sung Chit Cheung Matthew
Published: May 2013

English nowadays plays an important role in the political, diplomatic, commercial, economic and cultural activities on the global stage (see, e.g., Graddol, 1997, 2006; Jenkins, 2000; Warschauer, 2000; Crystal, 2003). As a result of the widespread use of English around the globe, several scholars contend that English no longer exclusively represents the culture of native English-speaking countries, nor are they the exclusive ‘owners’ of English (see e.g. Widdowson, 1994).
Substrate influence: from spelling pronunciation to pronunciation spelling – a growing trend among university students in Kenya
Authors: Waitiki Serah
Published: May 2013

The development of African varieties of English has been attributed to a variety of factors, and the emergent forms of English spoken in various African countries have been the subject of study for several decades now. Among the factors mentioned as leading to the ‘Africanness’ of African Englishes is the exposure to written language, which tends to lead to the observation of linkages between spelling and pronunciation in some of these varieties of English (Schmied, 1991a, 2006). The argument has been that due to exposure to the written word, second language learners reproduce elements of written language in speech, leading, for example, to the pronunciation of silent letters in words such as ‘heir’, ‘tomb’ etc. This phenomenon of ‘spelling pronunciation’ is more pronounced in some varieties than in others, and the practice may not be confined to non-native environments. In general, spelling pronunciation has been shown to lead to cross-cultural miscommunication and therefore has implications for English as a global language.
‘One panini, two paninis…’: the grammar of Italian culinary culture in Britain today
Authors: Dunnett Jane
Published: May 2013

I still recall, with a mixture of amusement and embarrassment, the time I took a visiting Italian friend to lunch in a café along London's Holloway Road. After studying the menu, he ordered a mozzarella and tomato panino – ‘so that'll be one panini for you’, jotted down the young woman behind the counter. My friend confirmed his choice by repeating it in a way that signified he could speak only for himself. And to make his point, he leaned somewhat on the singular -o of the ending, keen, I imagined, to avoid the kind of mix-up that leads to extra portions being brought to one's restaurant table in error. But to no avail: before proceeding to take his order, our waitress told my companion firmly, in an unmistakeably eastern European accent, that he would be having a ‘mozzarella and tomato panini’, and that was that.
Zielinstruktionen, räumliche Quiet-Eye-Verankerung und Bewegungsparametrisierung
Authors: Klostermann André , Koedijker Johan , Hossner Ernst-Joachim
Published: May 2013

Die motorikwissenschaftliche Befundlage zum sogenannten „Quiet Eye“ weist darauf hin, dass hohe sportmotorische Leistungen, insbesondere in Präzisionsaufgaben, mit einer langen finalen Fixation vor der Bewegungsentfaltung einhergehen. Ein Mechanismus, der diesen Zusammenhang aus einer kognitionspsychologischen Perspektive erklären könnte, ist die Optimierung von Informationsverarbeitungsprozessen der Bewegungsparametrisierung. Diese Annahme wurde durch eine experimentelle Manipulation von Zielinstruktionen in einer Ballwurfaufgabe untersucht. Zum einen zeigen die Ergebnisse, dass sich die räumliche Verankerung des Quiet Eye in Abhängigkeit der variierten Aufgabenziele verändert; zum anderen deuten die Befunde darauf hin, dass sich Veränderungen der Verankerung im Bewegungsresultat niederschlagen. Damit wird ein kognitiver Wirkmechanismus plausibilisiert, nach dem die Bewegungsgenauigkeit durch Zielinstruktion via räumliche Quiet-Eye-Verankerung bestimmt wird.
Failure of Collateral Blood Flow is Associated with Infarct Growth in Ischemic Stroke
Authors: Campbell Bruce CV , Christensen Søren , Tress Brian M , Churilov Leonid , Desmond Patricia M , Parsons Mark W , Barber P Alan , Levi Christopher R , Bladin Christopher , Donnan Geoffrey A , Davis Stephen M
Published: May 2013

Changes in collateral blood flow, which sustains brain viability distal to arterial occlusion, may impact infarct evolution but have not previously been demonstrated in humans. We correlated leptomeningeal collateral flow, assessed using novel perfusion magnetic resonance imaging (MRI) processing at baseline and 3 to 5 days, with simultaneous assessment of perfusion parameters. Perfusion raw data were averaged across three consecutive slices to increase leptomeningeal collateral vessel continuity after subtraction of baseline signal analogous to digital subtraction angiography. Changes in collateral quality, Tmax hypoperfusion severity, and infarct growth were assessed between baseline and days 3 to 5 perfusion-diffusion MRI. Acute MRI was analysed for 88 patients imaged 3 to 6 hours after ischemic stroke onset. Better collateral flow at baseline was associated with larger perfusion-diffusion mismatch (Spearman's Rho 0.51, P < 0.001) and smaller baseline diffusion lesion volume (Rho − 0.70, P < 0.001). In 30 patients without reperfusion at day 3 to 5, deterioration in collateral quality between baseline and subacute imaging was strongly associated with absolute ( P = 0.02) and relative ( P < 0.001) infarct growth. The deterioration in collateral grade correlated with increased mean Tmax hypoperfusion severity (Rho − 0.68, P < 0.001). Deterioration in Tmax hypoperfusion severity was also significantly associated with absolute ( P = 0.003) and relative ( P = 0.002) infarct growth. Collateral flow is dynamic and failure is associated with infarct growth.
A Nonlinear Mixed Effects Pharmacokinetic Model for Dapagliflozin and Dapagliflozin 3‐O‐glucuronide in Renal or Hepatic Impairment
Authors: van der Walt J‐S , Hong Y , Zhang L , Pfister M , Boulton DW , Karlsson MO
Published: May 2013

Dapagliflozin is a sodium–glucose co‐transporter 2 inhibitor in development for the treatment of type 2 diabetes mellitus. A semi‐mechanistic population pharmacokinetic (PK) model was developed for dapagliflozin and its inactive metabolite dapagliflozin 3‐O‐glucuronide (D3OG) with emphasis on renal and hepatic contribution to dapagliflozin metabolism. Renal and hepatic impairment decreased the clearance of dapagliflozin to D3OG and the clearance of D3OG. The fraction of D3OG formed via the renal route decreased from 40–55% in subjects with normal renal function (creatinine clearance (CLcr) > 80 ml/min) to 10% in subjects with severe renal insufficiency (CLcr = 13 ml/min). The model‐based simulations suggested that the increase of systemic exposure (AUCss) of dapagliflozin and D3OG was less than twofold in subjects with mild or moderate renal impairment. This population modeling analysis presents a useful approach to evaluate the impact of renal and hepatic function on the PK of dapagliflozin.

CPT: Pharmacometrics & Systems Pharmacology (2013) 2, e42; doi:10.1038/psp.2013.20; advance online publication 8 May 2013
Quantum anti-Zeno effect without wave function reduction
Authors: Ai Qing , Xu Dazhi , Yi Su , Kofman A. G. , Sun C. P. , Nori Franco
Published: May 2013

We study the measurement-induced enhancement of the spontaneous decay for a two-level subsystem, where measurements are treated as couplings between the excited state and an auxiliary state rather than the von Neumann's wave function reduction. The photon radiated in a fast decay of the atom, from the auxiliary state to the excited state, triggers a quasi-measurement, as opposed to a projection measurement. Our use of the term “quasi-measurement” refers to a “coupling-based measurement”. Such frequent quasi-measurements result in an exponential decay of the survival probability of atomic initial state with a photon emission following each quasi-measurement. Our calculations show that the effective decay rate is of the same form as the one based on projection measurements. The survival probability of the atomic initial state obtained by tracing over all the photon states is equivalent to that of the atomic initial state with a photon emission following each quasi-measurement.
Electronic excitation and structural relaxation of the adenine dinucleotide in gas phase and solution
Authors: Plasser Felix , Lischka Hans
Published: May 2013

The excited states and potential surfaces of the adenine dinucleotide are analyzed in gas phase and in solution using a correlatedab initiomethodology in a QM/MM framework. In agreement with previous studies, a rather flat S1surface with a number of minima of different character is found. Specifically, our results suggest that exciplexes with remarkably short intermolecular separation down to ≈2.0 Å are formed. A detailed analysis shows that due to strong orbital interactions their character differs significantly from any states present in the Franck-Condon region. The lowest S1energy minimum is a ππ* exciplex with only a small amount of charge transfer. It possesses appreciable oscillator strength with a polarization almost perpendicular to the planes of the two adenine molecules.
Electromechanical and magnetic properties of BiFeO3-LaFeO3-CaTiO3 ceramics near the rhombohedral-orthorhombic phase boundary
Authors: Karpinsky D. V. , Troyanchuk I. O. , Sikolenko V. , Efimov V. , Kholkin A. L.
Published: May 2013

BiFeO3-LaFeO3-CaTiO3 ceramics have been studied by X-ray diffraction, magnetization measurements, and piezoresponse force microscopy (PFM). The compositional ranges of the polar, antipolar, and non-polar phases have been estimated. PFM measurements testify gradual decrease of piezoelectric response in Bi0.85−xLa0.15CaxFe1−xTixO3 system with Ca/Ti content increase, except a narrow concentration region near polar-antipolar phase boundary where piezoelectric signal shows maximum value. It is found that increase of dopant concentration leads to apparent decrease of the off-center Bi-O displacement and, consequently, causes a reduction of piezoelectric response. It is concluded that notable remanent magnetization in polar and non-polar structural phases is a result of the Dzyaloshinsky-Moria interaction.
Nanodimensional spinel NiFe2O4 and ZnFe2O4 ferrites prepared by soft mechanochemical synthesis
Authors: Ž. Lazarević Z. , Jovalekić Č. , Milutinović A. , Sekulić D. , Ivanovski V. N. , Rečnik A. , Cekić B. , Ž. Romčević N.
Published: May 2013

NiFe2O4 and ZnFe2O4 ferrites have been prepared by soft mechanochemical synthesis. The formation of spinel phase and crystal structure of sintered powders were analyzed by X-ray diffraction, Raman spectroscopy, and transmission microscopy. In order to confirm phase formation and cation arrangement, Mössbauer measurements were done. Investigation of the magnetization as a function of magnetic field confirms an expected change of the degree of inversion in the spinel structure with the sintering. The electrical DC/resistivity/conductivity was measured in the temperature range of 298-423 K. Impedance spectroscopy was performed in the wide frequency range (100 Hz-10 MHz) at different temperatures.
Ferroelectric and magnetic properties of Fe-doped BaTiO3 thin films grown by the pulsed laser deposition
Authors: Venkata Ramana E. , Yang S. M. , Jung Ranju , Jung M. H. , Lee B. W. , Jung C. U.
Published: May 2013

Fe-doped BaTiO3 thin films were grown on (001) oriented SrTiO3 substrates using pulsed-laser deposition technique. These films had a single-phase character and good epitaxial relationship with the substrate. Polarization-electric field (P-E) hysteresis revealed saturated polarization with remnant polarization (Pr) of 13.5 μC/cm2 for 10 mol.  % Fe-doped BaTiO3 films. Further increase of composition resulted in the large leakage currents and reduction of polarization. The piezoelectric domain switching in the films was confirmed by local hysteresis using piezoelectric force microscopy measurements. The Fe-doped BaTiO3 thin films exhibited room temperature ferromagnetism, and the magnetization value increased with increasing Fe concentration. Our results demonstrate that the addition of Fe ≤10 mol.  % in BaTiO3 induces the ferromagnetism and a switchable ferroelectric state.
Polarization reversal induced by heating-cooling cycles in MgO doped lithium niobate crystals
Authors: Shur V. Ya. , Mingaliev E. A. , Lebedev V. A. , Kuznetsov D. K. , Fursov D. V.
Published: May 2013

Polarization reversal during heating-cooling cycles was investigated in MgO doped lithium niobate (MgO:LN) crystal using piezoresponse force microscopy. The essential dependence of the domain structure evolution scenario on the maximal temperature in the cycle has been revealed experimentally. It has been shown that the heating of the engineered domain matrix from room temperature to 85 °C leads to light size reduction of the isolated domains at the matrix edges, whereas the heating to 170 °C leads to essential reduction of the domain size. The opposite strong effect of the domain formation and growth during cooling after pulse heating have been revealed in single domain MgO:LN. The simulation of the time dependence of the pyroelectric field during heating-cooling cycle allowed to reveal the temperature hysteresis and to explain all observed effects taking into account the temperature dependence of the bulk conductivity.
Resolving ferroelectric nanostructures via piezoresponse force microscopy—A numerical investigation
Authors: Pan K. , Liu Y. M. , Liu Y. Y. , Li J. Y.
Published: May 2013

A numerical approach has been developed to study the spatial resolution of piezoresponse force microscopy (PFM) in resolving ferroelectric nanostructures, capable of analyzing complicated domain patterns with arbitrary three-dimensional heterogeneity. It is found that the spatial resolution of PFM is limited by long range electroelastic interactions, resulting in a nominal domain wall thickness over which piezoresponse varies, even if the probed domain wall is sharp. It is also observed that ferroelectric features smaller than probe tip radius can be resolved, and tilted domain wall tends to show larger nominal domain wall thickness, resulting in poorer lateral PFM resolution than vertical one. Probing ferroelectric structures underneath of the surface by PFM is also demonstrated.
In situ observation of the nanocrystal growth and their piezoelectric performance change in P(VDF-TrFE) films by hot stage piezoresponse force microscopy
Authors: Guo Dong , Chen Xiaosui , Chu Xiangcheng , Zeng Fei , Bai Yang , Cao Jiangli , Dkhil Brahim
Published: May 2013

We report the growth process of nanocrystals in spin-coated P(VDF-TrFE) films and the corresponding change in piezoelectric response by using in situ hot stage piezoresponse force microscopy (PFM). Upon annealing, irregularly shaped grains of the as-deposited film gradually grew up, and leaf-shaped grains with rather different piezoelectric response were formed above 120 °C. PFM images indicated that the individual grains in the P(VDF-TrFE) film were highly ordered nanocrystals having uniform molecular orientation, while different nanocrystals might show different molecular orientation. At 150 °C, which is higher than the Curie temperature of the material, the nanocrystals still showed a strong piezoelectric response despite the appearance of melt phase. This reveals a diffused transition in piezoelectric response that is related to the coexistence of crystalline and amorphous phases in the copolymer material. An annealing induced molecular reorientation observed by PFM was also confirmed by other characterization techniques.
Surface screening of written ferroelectric domains in ambient conditions
Authors: Segura J. J. , Domingo N. , Fraxedas J. , Verdaguer A.
Published: May 2013

We have combined Piezoresponse Force Microscopy and Kelvin Probe Force Microscopy (KPFM) to study screening charge dynamics in written domains on PbZr0.2Ti0.8O3 (PZT) thin film surfaces under a controlled environment and at variable temperature. The screening dynamics decayed exponentially on a timescale of tens of minutes, consistently with what we expected for water-mediated surface diffusion of ionic species. Variable-temperature KPFM measurements showed variations in surface potential due to temporary unbalanced surface screening charges. Low humidity experiments revealed gradual incorporation of positive charges onto the surface, even in a non-reactive environment (N2), as well as deceleration of the screening dynamics upon reversal of the temperature variation. Our work may serve as a guide for future studies on the dynamics and nature of adsorbates on polarized PZT thin films.
Lifting general relativity to observer space
Authors: Gielen Steffen , Wise Derek K.
Published: May 2013

The “observer space” of a Lorentzian spacetime is the space of future-timelike unit tangent vectors. Using Cartan geometry, we first study the structure a given spacetime induces on its observer space, then use this to define abstract observer space geometries for which no underlying spacetime is assumed. We propose taking observer space as fundamental in general relativity, and prove integrability conditions under which spacetime can be reconstructed as a quotient of observer space. Additional field equations on observer space then descend to Einstein's equations on the reconstructed spacetime. We also consider the case where no such reconstruction is possible, and spacetime becomes an observer-dependent, relative concept. Finally, we discuss applications of observer space, including a geometric link between covariant and canonical approaches to gravity.
Force and torque on a cylinder rotating in a narrow gap at low Reynolds number: Scaling and lubrication analyses
Authors: Yang J. , Wolgemuth C. W. , Huber G.
Published: May 2013

The hydrodynamic forces and torques on a rotating cylinder in a narrow channel are investigated in this paper using lubrication analysis and scaling analysis. To explore the effect of the shape of the gap, three different geometries are considered. The force and torque expressions from lubrication analysis agree well with numerical solutions when the gap between cylinder and wall is small. The solutions from scaling analysis can be applied over a broader range, but only if the scaling coefficients are properly deduced from numerical solution or lubrication analysis. Self-similarity in the solutions is discussed as well.
From light-scattering measurements to polarizability derivatives in vibrational Raman spectroscopy: The 2ν5 overtone of SF6
Authors: Kremer D. , Rachet F. , Chrysos M.
Published: May 2013

The room-temperature isotropic spectrum of SF6 was recorded at the frequency of the 2ν5 overtone by running high-sensitivity incoherent Raman experiments for two independent polarizations of the incident beam and for gas densities varying from 2 to 27 amagat. Weak yet observable pressure effects were found. A transparent analysis of the Raman cross-section problem along with the first-ever prediction of the value of the mean polarizability second derivative \documentclass[12pt]{minimal}\begin{document}$\partial ^{2}\bar{\alpha }/\partial q_{5}^{2}$\end{document}∂2α¯/∂q52 are made and the hitherto underestimated role of the hot bands of SF6 is brought to the wider public. The emergence of an analytic hotband factor is shown whose magnitude is dramatically increased with the order of the overtone and the gas temperature and all the more so upon considering low-frequency molecular vibrations. Our formulas, which in the harmonic approximation are exact, are still applicable to real situations provided certain conditions are fulfilled. For nondegenerated modes, generalization to higher order overtones is made, an issue addressing the much challenging problem of the IR-allowed second overtone bands. The content of this paper is also an invitation towards ab initio derivative-calculations for sulfur hexafluoride, especially given the today's needs in interpreting spectra of significance for greenhouse atmospheric issues.
Simulation of a suite of generic long-pulse neutron instruments to optimize the time structure of the European Spallation Source
Authors: Lefmann Kim , Klenø Kaspar H. , Birk Jonas Okkels , Hansen Britt R. , Holm Sonja L. , Knudsen Erik , Lieutenant Klaus , von Moos Lars , Sales Morten , Willendrup Peter K. , Andersen Ken H.
Published: May 2013

We here describe the result of simulations of 15 generic neutron instruments for the long-pulsed European Spallation Source. All instruments have been simulated for 20 different settings of the source time structure, corresponding to pulse lengths between 1 ms and 2 ms; and repetition frequencies between 10 Hz and 25 Hz. The relative change in performance with time structure is given for each instrument, and an unweighted average is calculated. The performance of the instrument suite is proportional to (a) the peak flux and (b) the duty cycle to a power of approximately 0.3. This information is an important input to determining the best accelerator parameters. In addition, we find that in our simple guide systems, most neutrons reaching the sample originate from the central 3–5 cm of the moderator. This result can be used as an input in later optimization of the moderator design. We discuss the relevance and validity of defining a single figure-of-merit for a full facility and compare with evaluations of the individual instrument classes.
High resolution photoelectron imaging of Au2−
Authors: León Iker , Yang Zheng , Wang Lai-Sheng
Published: May 2013

We report high resolution photoelectron spectra of Au2− using a newly built photoelectron imaging apparatus. Vibrationally resolved photoelectron images are obtained for the ground state detachment transition of Au2− at various photon energies (442.80–670.18 nm) at a resolution of 3 cm−1 for low energy electrons. Franck-Condon simulations yield the vibrational temperature of Au2− and the high resolution data yield accurate spectroscopic constants for the ground states of Au2 and Au2−. The electron affinity of Au2 is measured to be 1.9393 ± 0.0006 eV. A more precise value for the Au2− dissociation energy is also obtained as 1.937 ± 0.005 eV.
Characterizing heterogeneous dynamics at hydrated electrode surfaces
Authors: Willard Adam P. , Limmer David T. , Madden Paul A. , Chandler David
Published: May 2013

In models of Pt 111 and Pt 100 surfaces in water, motions of molecules in the first hydration layer are spatially and temporally correlated. To interpret these collective motions, we apply quantitative measures of dynamic heterogeneity that are standard tools for considering glassy systems. Specifically, we carry out an analysis in terms of mobility fields and distributions of persistence times and exchange times. In so doing, we show that dynamics in these systems is facilitated by transient disorder in frustrated two-dimensional hydrogen bonding networks. The frustration is the result of unfavorable geometry imposed by strong metal-water bonding. The geometry depends upon the structure of the underlying metal surface. Dynamic heterogeneity of water on the Pt 111 surface is therefore qualitatively different than that for water on the Pt 100 surface. In both cases, statistics of this ad-layer dynamic heterogeneity responds asymmetrically to applied voltage.
Effective suppressibility of chaos
Authors: López Álvaro G. , Seoane Jesús M. , Sanjuán Miguel A. F.
Published: May 2013

Suppression of chaos is a relevant phenomenon that can take place in nonlinear dynamical systems when a parameter is varied. Here, we investigate the possibilities of effectively suppressing the chaotic motion of a dynamical system by a specific time independent variation of a parameter of our system. In realistic situations, we need to be very careful with the experimental conditions and the accuracy of the parameter measurements. We define the suppressibility, a new measure taking values in the parameter space, that allows us to detect which chaotic motions can be suppressed, what possible new choices of the parameter guarantee their suppression, and how small the parameter variations from the initial chaotic state to the final periodic one are. We apply this measure to a Duffing oscillator and a system consisting on ten globally coupled Hénon maps. We offer as our main result tool sets that can be used as guides to suppress chaotic dynamics.