bluuebunny/crossref_metadata_2025 huggingface dataset:
Preclinical high‐dose acetaminophen with N‐acetylcysteine rescue enhances the efficacy of cisplatin chemotherapy in atypical teratoid rhabdoid tumors
Authors: Neuwelt Alexander J. , Nguyen Tam , Wu Y. Jeffrey , Donson Andrew M. , Vibhakar Rajeev , Venkatamaran Sujatha , Amani Vladimir , Neuwelt Edward A. , Rapkin Louis B. , Foreman Nicholas K.
Published: August 2013

Background

Atypical teratoid rhabdoid tumors (AT‐RT) are pediatric tumors of the central nervous system with limited treatment options and poor survival rate. We investigated whether enhancing chemotherapy toxicity by depleting intracellular glutathione (GSH; a key molecule in cisplatin resistance) with high dose acetaminophen (AAP), may improve therapeutic efficacy in AT‐RT in vitro.

Procedure

BT16 (cisplatin‐resistant) and BT12 (cisplatin‐sensitive) AT‐RT cell lines were treated with combinations of AAP, cisplatin, and the anti‐oxidant N‐acetylcysteine (NAC). Cell viability, GSH and peroxide concentrations, mitochondrial damage, and apoptosis were evaluated in vitro.

Results

AAP enhanced cisplatin cytotoxicity in cisplatin‐resistant BT16 cells but not cisplatin‐sensitive BT12 cells. Baseline GSH levels were elevated in BT16 cells compared to BT12 cells, and AAP decreased GSH to a greater magnitude in BT16 cells than BT12 cells. Unlike BT12 cells, BT16 cells did not have elevated peroxide levels upon treatment with cisplatin alone, but did have elevated levels when treated with AAP + cisplatin. Both cell lines had markedly increased mitochondrial injury when treated with AAP + cisplatin relative to either drug treatment alone. The enhanced toxic effects were partially reversed with concurrent administration of NAC.

Conclusions

Our results suggest that AAP could be used as a chemo‐enhancement agent to potentiate cisplatin chemotherapeutic efficacy particularly in cisplatin‐resistant AT‐RT tumors with high GSH levels in clinical settings. Pediatr Blood Cancer 2014;61:120–127. © 2013 Wiley Periodicals, Inc.
Justification for Chest Physiotherapy during Ultra‐Protective Lung Ventilation and Extra‐Corporeal Membrane Oxygenation: A Case Study
Authors: Cork G. , Barrett N. , Ntoumenopoulos G.
Published: August 2013

Background and purpose

This case report describes the chest physiotherapy (CPT) intervention provided to a 32‐year old man with severe respiratory failure undergoing extra‐corporeal membrane oxygenation (ECMO) support and ultra‐protective ventilatory strategy. Low tidal volume ventilation when used in patients with extremely low dynamic respiratory compliance may predispose the patient to secretion retention, and the role of CPT in this setting is unclear.

Method

The method used is a single subject case report. Written consent obtained from patient's representative.

Secretion clearance in this patient was initially limited to suctioning; however, after developing major airway occlusion secondary to impacted secretions, he received intensive CPT consisting of positioning, ventilator hyperinflation, expiratory chest wall shaking and suctioning. After 13 days of two to three times daily CPT, the patient weaned from ECMO support.

Discussion

Regular CPT may have facilitated secretion clearance and lung recovery in this patient. Future research should investigate the optimal CPT techniques for patients with sub‐dead space tidal ventilation and extremely low dynamic respiratory compliance during ECMO with ultra‐protective ventilatory strategy (UPVS). Copyright © 2013 John Wiley & Sons, Ltd.
Akt Suppression of TGFβ Signaling Contributes to the Maintenance of Vascular Identity in Embryonic Stem Cell-Derived Endothelial Cells
Authors: Israely Edo , Ginsberg Michael , Nolan Daniel , Ding Bi-Sen , James Daylon , Elemento Olivier , Rafii Shahin , Rabbany Sina Y.
Published: August 2013

The ability to generate and maintain stable in vitro cultures of mouse endothelial cells (ECs) has great potential for genetic dissection of the numerous pathologies involving vascular dysfunction as well as therapeutic applications. However, previous efforts at achieving sustained cultures of primary stable murine vascular cells have fallen short, and the cellular requirements for EC maintenance in vitro remain undefined. In this study, we have generated vascular ECs from mouse embryonic stem (ES) cells and show that active Akt is essential to their survival and propagation as homogeneous monolayers in vitro. These cells harbor the phenotypical, biochemical, and functional characteristics of ECs and expand throughout long-term cultures, while maintaining their angiogenic capacity. Moreover, Akt-transduced embryonic ECs form functional perfused vessels in vivo that anastomose with host blood vessels. We provide evidence for a novel function of Akt in stabilizing EC identity, whereby the activated form of the protein protects mouse ES cell-derived ECs from TGFβ-mediated transdifferentiation by downregulating SMAD3. These findings identify a role for Akt in regulating the developmental potential of ES cell-derived ECs and demonstrate that active Akt maintains endothelial identity in embryonic ECs by interfering with active TGFβ-mediated processes that would ordinarily usher these cells to alternate fates. Stem Cells  2014;32:177–190
Adult ESOL Students and Service‐Learning: Voices, Experiences, and Perspectives
Authors: Bippus Sharon L. , Eslami Zohreh R.
Published: August 2013

This multiple‐case study examined the unique perspectives of six adult English for speakers of other languages (ESOL) students who participated as the givers of a service in a semester‐long service learning community college ESOL course. Their ages ranged from 19 to 45 and they hailed from five different countries (Colombia, Mexico, South Korea, Venezuela, and Vietnam). This study focused on the students' perspectives regarding their oral communication skills, and specific examples have been drawn from sources such as student journals, reflection papers, projects, semistructured interviews, and personal observations. The benefits identified by the participants include becoming more active learners, developing an appreciation of learning in an authentic atmosphere, and gaining self‐confidence. Challenges overcome include language barriers and feelings of fear and incompetence.
Developing Multiple Literacies in Academic English Through Service‐Learning and Community Engagement
Authors: Askildson Lance R. , Kelly Annie Cahill , Mick Connie Snyder
Published: August 2013

Research on service‐learning offers compelling evidence of the advances student learners make in moral development, orientation to prosocial behavior, and curricular content retention. But who are those student learners? Most studies focus on native, dominant‐culture, dominant‐language students serving marginalized populations. Studies of the United States, for example, primarily focus on English‐speaking U.S. citizens serving either linguistically and culturally similar populations marked by economic, educational, or health vulnerabilities, or linguistically and culturally different populations to facilitate the acquisition of another language or cultural tradition, such as tutoring at a Latino community center in order to learn Spanish. Much less research has focused on English language learners as agents of service in the United States, volunteering at U.S. social service agencies in order to increase their own acquisition of the English language and U.S. culture. This study addresses that gap in the research by analyzing results of a language immersion program that aimed to develop multiple literacies in academic English through service‐learning and community engagement. The study documents significant gains in intercultural awareness and advanced language acquisition over 8 weeks of service‐learning, recommending service‐learning as an exceptional pedagogical mechanism for domestic and international programs in intercultural development and second language acquisition.
Impacts and management of invasive cool‐season grasses in the Northern Great Plains: Challenges and opportunities for wildlife
Authors: Ellis‐Felege Susan N. , Dixon Cami S. , Wilson Scott D.
Published: August 2013

Grasslands of the Northern Great Plains of North America are in the midst of extensive human‐driven loss and redistribution of important species. Invasive plants contribute to degradation of this ecosystem and present monumental challenges for natural resource managers. Widespread decreases in populations of grassland‐dependent wildlife, particularly birds, have been documented, but relatively little research has been focused on direct responses of wildlife to invading plants relative to native vegetation. Smooth brome (Bromus inermis) and Kentucky bluegrass (Poa pratensis) are 2 invasive cool‐season grass species found across much of the Northern Great Plains that continue to expand despite management actions intended to reduce them. With eradication unlikely, creativity, cooperation, and science‐based management (e.g., Adaptive Management) are paramount to protect and restore the integrity of grassland habitats across the Northern Great Plains. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.
Luffa cylindrica and phytosterols bioconversion: from shake flask to jar bioreactor
Authors: Bou Saab Hamid , Fouchard Samuel , Boulanger Anna , Llopiz Pierre , Neunlist Serge
Published: August 2013

Bioconversion of lipophilic compounds poorly soluble in water, such as sterols, required the use of chemicals and solubilizing agents. On the other hand, it was shown that immobilization of Mycobacterium species on the dried fruit of Luffa cylindrica (DFLC) allows a close interaction between immobilized cells and cholesterol particles and increases by then the product’s yield. In this work, the use of DFLC in a 5-l jar bioreactor with phytosterols mixture (1 g/l) as substrate was assessed without addition of any chemicals or solubilizing agents. DFLC increased by a factor of four the volumetric productivity of androstenones (0.08 g/l day). Products were accumulated in the aqueous medium while substrates remained on the fibers of DFLC. This observation lets envisage a green semi-continuous process of androstenone production. DFLC has no influence on cell growth, and is moreover natural, inexpensive, non-toxic, and mechanically strong.
Attitude of Medical School Students in China Towards Genetic Testing and Counseling Issues in FXS
Authors: Li Jia , Huang Wen , Luo Shiyu , Lin Yunting , Duan Ranhui
Published: August 2013

Fragile X syndrome (FXS) is the most common form of inherited intellectual disability. However, genetic testing protocols and genetic counseling guidelines for FXS are not yet established in mainland China. In the present study, we conducted a comprehensive analysis using a self‐administered questionnaire among students at the Xiangya medical school to investigate their attitude towards genetic testing and counseling issues of FXS. We have gained a general understanding of the attitudes of medical students towards these FXS issues in China. This information is of immense importance to develop appropriate genetic tests and to train counselors for FXS. As the medical school students surveyed are prospective physicians who will be a part of the Chinese health system, our survey was focused on the basic knowledge of FXS, population‐based FXS screening, confidentiality and reproductive options for mutation carriers. The study demonstrated that only less than one third of the participants had heard about FXS. 94.6 % of participants were in favor of FXS screening for women in their reproductive age who had a genetic history of FXS. Furthermore, only half of the participants would inform their families about their genetic status in case of positive test results, and more than half of the participants supported natural conception and prenatal diagnosis for FXS mutation carriers. Additional findings and research implications are also discussed. This survey targeting potential doctors provides important information for the development of FXS genetic test and counselor training for the Chinese health system.
Research on the Influence of the Type of Surfactant and Concentrator in Aqueous Dispersion of Pigments
Authors: Makarewicz Edwin , Michalik Agnieszka
Published: August 2013

This work reports tests performed to evaluate the stability of aqueous dispersions of inorganic oxide pigments with different specific surface areas, with the use of anionic and non‐ionic surfactants and concentrators. Color mixtures of oxide compounds of blue, green, olive and brown with the unit cell spinel structure were used as pigments. The sodium salt of sulfosuccinic acid monoester, oxyethylenated nonylphenol and ethoxylated derivatives of lauryl alcohol, fatty alcohol and fatty amine were used as surfactants. The concentrators used were: poly(vinyl alcohol), the sodium salt of carboxymethyl cellulose as well as a water‐based polyurethane oligomer. The highest dispersion efficiency was found for dispersed systems in which surfactant and concentrator were incorporated in the formula. The one containing the sodium salt of carboxymethyl cellulose or polyurethane oligomer with ethoxylated saturated fatty alcohol or fatty amine was found to be the most efficient. It was discovered that a higher dispersion efficiency corresponds to pigments with larger specific surface. The efficiency is also found to improve when the concentrator is an acrylic polymer or copolymer made up of two acrylic species. In this case, the concentrator interaction with the surfactant is more effective if the value of its boundary viscosity number is higher. This observation confirms the existence of interactions between macro‐chains of the concentrator and surfactant molecules forming micelles with the pigment particles.
Electrostatic Effect on Synergism of Wormlike Micelles and Hydrophobically Modified Polyacrylic Acid
Authors: Mei Yongjun , Han Yixiu , Wang Hang , Xie Lin , Zhou Hong
Published: August 2013

The electrostatic effects on the synergism between wormlike micelles and hydrophobically modified polyacrylic acid (HMPA) have been investigated by rheological measurements and dissipative particle dynamics molecular simulation (DPD). Both cationic surfactants, cetyltrimethylammonium bromide (CTAB), and anionic surfactant, sodium oleate (NaOA), were employed to construct wormlike micelles, and the influences of both simple salts, NaBr or NaAc, and hydrophobic salts, sodium benzoate (NaBen) and benzyltrimethyl ammonium bromide (BTAB), were discussed. The synergistic effects vary with the headgroup charge and the counterions property of surfactants. For the NaOA system, the obvious viscosity maximum was observed only at low NaAc content, while a monotonous viscosity increase appeared at a high content of BTAB. However, the optimal synergism can be only observed in the presence of concentrated NaBen in CTAB system. DPD molecular simulation provides a support and favorable illustration for the synergism mechanism. It suggests that not only the hydrophobic interaction but also the electrostatic interaction has an important impact on the synergism between ionic wormlike micelles and HMPA.
Moderate Compared to Low Dietary Intake of trans‐Fatty Acids Impairs Strength of Old and Aerobic Capacity of Young SAMP8 Mice in Both Sexes
Authors: Liou Jesse , Tuazon Marc A. , Burdzy Alex , Henderson Gregory C.
Published: August 2013

The senescence accelerated SAMP8 mouse is a model for sarcopenia and provides an opportunity to study the effects of lifelong dietary composition on the loss of physical function with age. We studied the effects of trans‐fatty acids (2 % of total energy, TFA diet) on the loss of strength and aerobic exercise capacity (VO2peak) with age. SAMP8 mice were studied at two ages (young, 25 weeks; old, 60 weeks) and on two diets (control vs TFA). Body composition, grip strength, VO2peak, blood metabolites, and biochemical parameters were assessed. Body weight, fat mass, and body fat percentage all increased with age (p < 0.05) but were not significantly impacted by diet. There was a significant age‐related decline in total grip strength as well as that normalized to fat‐free mass (FFM) (p < 0.05) with a further decrease at old age in these metrics of strength on the TFA diet vs control diet (p < 0.05). Total VO2peak exhibited no change with age or diet, but when normalized to FFM, VO2peak exhibited age and TFA‐related declines (p < 0.05). Intramuscular triacylglycerol (p < 0.05) and collagen content (p < 0.05) significantly increased with age, while blood triacylglycerol was increased by the TFA diet (p < 0.05). These data further characterize the SAMP8 mouse as a model for sarcopenia and indicate that dietary fatty acid composition can impact the degree of this age‐related loss of physical function.
Experimental Solid–Liquid Phase Equilibria of a Methyl Ester/Amide/Nitrile Ternary System by DSC
Authors: Mekki‐Berrada A. , Bennici S. , Dubois J.‐L. , Auroux A.
Published: August 2013

Binary and ternary mixtures of lauric methyl ester, amide and nitrile were investigated by differential scanning calorimetry, in order to determine the solid–liquid phase equilibria of this model for saturated organic systems. Eutectic mixtures were observed and followed in the ternary system, while solid–solid transitions and immiscibility phenomena were also characterized. This system is also of industrial interest for processes in the frame of biomass valorization.
Autophosphorylation of gatekeeper tyrosine by symbiosis receptor kinase
Authors: Samaddar Sandip , Dutta Ayan , Sinharoy Senjuti , Paul Anindita , Bhattacharya Avisek , Saha Sudip , Chien Ko-yi , Goshe Michael B. , DasGupta Maitrayee
Published: August 2013

Plant receptor‐like kinases (RLKs) share their evolutionary origin with animal interleukin‐1 receptor‐associated kinase (IRAK)/Pelle family of soluble kinases and are distinguished by having tyrosine as ‘gatekeeper’. This position is adjacent to the hinge region and is hidden in a hydrophobic pocket of the catalytic cleft of protein kinases and is therefore least probable to be a target for any modification. This communication illustrates the accessibility of the gatekeeper site (Y670) towards both autophosphorylation and dephosphorylation in the recombinant cytoplasmic domain of symbiosis receptor kinase from Arachis hypogaea (AhSYMRK). Autophosphorylation on gatekeeper tyrosine was detected prior to extraction but never under in vitro conditions. We hypothesize gatekeeper phosphorylation to be associated with synthesis/maturation of AhSYMRK and this phenomenon may be prevalent among RLKs.
Package size and perceived quality: The intervening role of unit price perceptions
Authors: Yan Dengfeng , Sengupta Jaideep , Wyer Robert S.
Published: August 2013

This research examines how package size can influence quality judgments for packaged goods, and also identifies a price‐based mechanism for the observed size–quality relationship. Results from several studies show that a product in a smaller package is rated more favorably than the equivalent product in a larger package. Further, this effect is due to the smaller package being associated with a higher unit price (despite having a lower overall price), which suggests that unit price information is more diagnostic than overall price information when forming judgments of product quality. We also find a theoretically‐derived reversal of this effect under conditions in which the greater diagnosticity of unit price is overwhelmed by its lower ease of use. Namely, when overall price is the only explicitly‐provided price cue and consumers are too distracted to estimate unit price, a larger package is now rated as being better. Finally, two concluding studies examine the downstream consequences of changes in package size, building off our basic conceptualization to document effects on product choice as well as consumption experience.
Contradictions of democratic education: International teachers’ perspectives on democracy in American schools
Authors: Mathews Sarah A. , Spearman Mindy J. , Che S. Megan
Published: August 2013

This study highlights a range of perspectives offered by 11 international teachers, participating in a cultural immersion experience, as they reflect on how they saw democracy manifested at their school internships. Teachers from six different countries studied and taught in a rural community in the Southern United States, where a medium-sized research university hosted the teachers as part of a federally-funded program during an academic semester. As a part of a larger qualitative research study analyzing the international teachers’ perception of American schooling, data from intercultural sessions, individual interviews, and assigned reaction papers highlighted multiple contradictions between the teachers’ interpretation of democratic ideals and democratic education as they saw manifested in American schools. These narratives highlight the complex forces that shape individuals’ perceptions of democracy as played out in the everyday life of a cultural immersion experience. The researchers suggest that these transnational perspectives can serve as a mechanism allowing Western educators to listen to the “Other” as they interrogate taken-for-granted assumptions about American schooling. Narratives primarily highlight inconsistencies between the goals of citizenship education and the way in which citizenship is promoted or neglected in K-12 classrooms.
Alteration in the global and regional myocardial strain patterns in patients with inferior ST‐elevation myocardial infarction prior to and after percutaneous coronary intervention
Authors: Song Chen‐Fang , Zhou Qing , Guo Rui‐Qiang
Published: August 2013

This study was designed to investigate the alteration on regional and global strains of left and right ventricle (LV, RV) in patients with inferior wall ST‐elevation myocardial infarction (MI). Patients were examined prior to and 7 days after percutaneous coronary intervention (PCI) using speckle‐tracking techniques. Fifty‐nine patients (36 males and 23 females) and 60 healthy controls (40 males and 20 females) were enrolled in this study. LV strains were measured from three deformations including radial, longitudinal, and circumferential. RV strains were measured only from the longitudinal. Three types of LV global strains were significantly lower in patients than in controls, and LV global longitudinal and circumferential strains were moderately improved by PCI. The LV regional strains reduced significantly in most of the segments (87%) after inferior wall MI and over half of them (60%) were improved by PCI. The RV global longitudinal strains were significantly lower in patients than in controls, and they were moderately improved by PCI. In conclusion, the regional and global strains of LV and RV were reduced in patients with inferior wall MI, and PCI most markedly improved the global strains and regional strains of the infarct and adjacent myocardium in the apical and middle levels.
Milnor descent for cohesive dg-categories
Authors: Ben-Bassat Oren , Block Jonathan
Published: August 2013

We show that the functor from curved differential graded algebras to differential graded categories, defined by the second author, sends Cartesian diagrams to homotopy Cartesian diagrams, under certain reasonable hypotheses. This is an extension to the arena of dg-categories of a construction of projective modules due to Milnor. As an example, we show that the functor satisfies descent for certain partitions of a complex manifold.
The Dissection of Paraprofessional Support in Inclusive Education: ‘You're in Mainstream With a Chaperone’
Authors: Whitburn Ben
Published: August 2013

The experiences of young people with disabilities of inclusive schooling are largely underresearched. This paper reports recent findings of a small-scale Australian qualitative study, in which secondary students with vision impairment spoke about their experiences of receiving paraprofessional support. Two overarching themes emerged from this study: ‘light’ and ‘heavy’ paraprofessional support. The results presented here demonstrate that participants described that support personnel upheld the strong arm of the special education tradition, which was manifestly detrimental to their inclusion. Raw data is presented to elucidate the emergent themes, and to explain the various pedagogical and general support roles of class and special educators in eliminating the need for direct paraprofessional presence in lessons. The light and heavy model of support is also examined in terms of how it fits into the complexity of the education discourse and the young people's own aspirations for full inclusion.
Sodium iron EDTA and ascorbic acid, but not polyphenol oxidase treatment, counteract the strong inhibitory effect of polyphenols from brown sorghum on the absorption of fortification iron in young women
Authors: Cercamondi Colin I. , Egli Ines M. , Zeder Christophe , Hurrell Richard F.
Published: August 2013

In addition to phytate, polyphenols (PP) might contribute to low Fe bioavailability from sorghum-based foods. To investigate the inhibitory effects of sorghum PP on Fe absorption and the potential enhancing effects of ascorbic acid (AA), NaFeEDTA and the PP oxidase enzyme laccase, we carried out three Fe absorption studies in fifty young women consuming dephytinised Fe-fortified test meals based on white and brown sorghum varieties with different PP concentrations. Fe absorption was measured as the incorporation of stable Fe isotopes into erythrocytes. In study 1, Fe absorption from meals with 17 mg PP (8·5 %) was higher than that from meals with 73 mg PP (3·2 %) and 167 mg PP (2·7 %;P< 0·001). Fe absorption from meals containing 73 and 167 mg PP did not differ (P= 0·9). In study 2, Fe absorption from NaFeEDTA-fortified meals (167 mg PP) was higher than that from the same meals fortified with FeSO4(4·6v.2·7 %;P< 0·001), but still it was lower than that from FeSO4-fortified meals with 17 mg PP (10·7 %;P< 0·001). In study 3, laccase treatment decreased the levels of PP from 167 to 42 mg, but it did not improve absorption compared with that from meals with 167 mg PP (4·8v.4·6 %;P= 0·4), whereas adding AA increased absorption to 13·6 % (P< 0·001). These findings suggest that PP from brown sorghum contribute to low Fe bioavailability from sorghum foods and that AA and, to a lesser extent, NaFeEDTA, but not laccase, have the potential to overcome the inhibitory effect of PP and improve Fe absorption from sorghum foods.
An Early Silurian ‘Herefordshire’ myodocope ostracod from Greenland and its palaeoecological and palaeobiogeographical significance
Authors: PERRIER VINCENT , SIVETER DAVID J. , WILLIAMS MARK , LANE PHILIP D.
Published: August 2013

Here we record the occurrence of a new species of the Herefordshire Lagerstätte ostracod genusPaulinefrom the Lower Silurian (upper Telychian) of North Greenland.Pauline nivisissp. nov. was recovered from a limestone boulder (Pentamerus Bjerge Formation) collected south of Kap Schuchert, Washington Land. It is reasonable to transpose the palaeobiology known from the HerefordshirePauline avibella– body, limbs including swimming antennae, lateral eyes, gills and alimentary system – into the carapace of the Greenland species, which represents the oldest cylindroleberidid myodocopid and almost the oldest known myodocope, and is the first record of a Herefordshire Lagerstätte genus from outside the Welsh Borderland locality. Morphological, sedimentological and faunal evidence suggest that the Greenland species was nektobenthic. This is compatible with the notion that ostracods (specifically myodocopids) did not invade the water column until later in the Silurian, in the Wenlock and Ludlow epochs.Paulineis an Early Silurian link between ‘Baltic-British’ and North Laurentian ostracod faunas, endorsing the idea that the UK and Greenland were in close geographical proximity, near a remnant Iapetus Ocean, during late Llandovery time.
Tonsil tie simulator
Authors: Duodu J , Lesser T H J
Published: August 2013

Background:

The surgical trainee has to acquire surgical skills in an era of reduced training hours and greater demands for efficient use of operating theatre time. Many surgical specialties are utilising model and simulation-based training to provide safe, low-pressure training opportunities for today's trainee.

Method and results:

This paper describes a simple, relatively inexpensive tonsillectomy model that enables the practice of tonsil removal and ligation of bleeding vessels. The model is beneficial for the patient, trainee and trainer.

Conclusion:

The pseudo mouth and active bleeding components of this model provide the trainee with a relatively inexpensive, realistic model with which to gain confidence and competence in the skill of ligating tonsillar blood vessels with a tonsil tie.
A ROBUST NEIGHBORHOOD TRUNCATION APPROACH TO ESTIMATION OF INTEGRATED QUARTICITY
Authors: Andersen Torben G. , Dobrev Dobrislav , Schaumburg Ernst
Published: August 2013

We provide a first in-depth look at robust estimation of integrated quarticity (IQ) based on high-frequency data. IQ is the key ingredient enabling inference about volatility and the presence of jumps in financial time series and is thus of considerable interest in applications. We document the significant empirical challenges for IQ estimation posed by commonly encountered data imperfections and set forth three complementary approaches for improving IQ-based inference. First, we show that many common deviations from the jump-diffusive null can be dealt with by a novel filtering scheme that generalizes truncation of individual returns to truncation of arbitrary functionals on return blocks. Second, we propose a new family of efficient robust neighborhood truncation (RNT) estimators for integrated power variation based on order statistics of a set of unbiased local power variation estimators on a block of returns. Third, we find that ratio-based inference, originally proposed in this context by Barndorff-Nielsen and Shephard (2002, Journal of Applied Econometrics 17, 457–477), has desirable robustness properties in the face of regularly occurring data imperfections and thus is well suited for empirical applications. We confirm that the proposed filtering scheme and the RNT estimators perform well in our extensive simulation designs and in an application to the individual Dow Jones 30 stocks.
Prevalence and molecular epidemiology of Staphylococcus aureus in Swedish nursing homes – as revealed in the SHADES study
Authors: STARK L. , OLOFSSON M. , LÖFGREN S. , MÖLSTAD S. , LINDGREN P.-E. , MATUSSEK A.
Published: August 2013

Knowledge of carriage and population dynamics of Staphylococcus aureus is crucial for infection risk assessment and to reveal transmission patterns of strains. We report the prevalence and molecular epidemiology of S. aureus in elderly people (n = 290) living in nursing homes in three cities in the south of Sweden. The overall carriage prevalence rate was 48% when results from nares (31%) and throat (34%) samples were combined. Common spa types were equally distributed but a frequent type, t160, was found only in one of the regions. Carriage of different spa types was detected in 23% of individuals and antimicrobial resistance rates were higher in S. aureus isolates from those carrying more than one spa type. Five of the 21 individuals who carried different spa types were colonized simultaneously with resistant and non-resistant strains. Seventeen per cent of the individuals carried S. aureus of the same spa type on all occasions. Methicillin resistance was not detected. In conclusion we found a high prevalence of S. aureus in this elderly population with a high rate of dual colonization with different spa types. We also found signs of institutional spread of one strain.
Campylobacteriosis in returning travellers and potential secondary transmission of exotic strains
Authors: MUGHINI-GRAS L. , SMID J. H. , WAGENAAR J. A. , DE BOER A. , HAVELAAR A. H. , FRIESEMA I. H. M. , FRENCH N. P. , GRAZIANI C. , BUSANI L. , VAN PELT W.
Published: August 2013

Multilocus sequence types (STs) were determined for 232 and 737Campylobacter jejuni/coliisolates from Dutch travellers and domestically acquired cases, respectively. Putative risk factors for travel-related campylobacteriosis, and for domestically acquired campylobacteriosis caused by exotic STs (putatively carried by returning travellers), were investigated. Travelling to Asia, Africa, Latin America and the Caribbean, and Southern Europe significantly increased the risk of acquiring campylobacteriosis compared to travelling within Western Europe. Besides eating chicken, using antacids, and having chronic enteropathies, we identified eating vegetable salad outside Europe, drinking bottled water in high-risk destinations, and handling/eating undercooked pork as possible risk factors for travel-related campylobacteriosis. Factors associated with domestically acquired campylobacteriosis caused by exotic STs involved predominantly person-to-person contacts around popular holiday periods. We concluded that putative determinants of travel-related campylobacteriosis differ from those of domestically acquired infections and that returning travellers may carry several exotic strains that might subsequently spread to domestic populations even through limited person-to-person transmission.
Augmentative transcranial direct current stimulation (tDCS) in poor responder depressed patients: a follow-up study
Authors: Dell'Osso Bernardo , Dobrea Cristina , Arici Chiara , Benatti Beatrice , Ferrucci Roberta , Vergari Maurizio , Priori Alberto , Altamura A. Carlo
Published: August 2013

Objectives

Transcranial direct current stimulation (tDCS) is a non-invasive neurostimulation technique that has received increasing interest in the area of mood disorders over the last several years. While acute, double-blind, sham-controlled studies have already reported positive findings in terms of efficacy and safety for tDCS, follow-up data are lacking. This need prompted the present follow-up study, which assesses post-acute effects of tDCS (no maintenance stimulation was performed), in the mid-term, in a sample of major depressives.

Methods

After completing an acute, open trial of tDCS, 23 outpatients with either major depressive disorder or bipolar disorder entered a naturalistic follow-up (T1) with clinical evaluations at one week (T2), 1 month (T3), and 3 months (T4). A quantitative analysis of Hamilton Depression Rating Scale (HAM-D), Montgomery–Asberg Depression Rating Scale (MADRS), and Young Mania Rating Scale (YMRS) total scores, through repeated measures analysis of variance (ANOVA) (T1–T4) and pairedt-test for comparing specific time points (T1–T2, T2–T3, and T3–T4), was performed. In addition, a qualitative analysis on the basis of treatment response and remission (HAM-D) was performed.

Results

Even though a progressive reduction of follow-up completers was observed from T2 to T4 (95.6% at T2, 65.2% at T3, and 47.8% at T4), the antidepressant effects of acute tDCS persisted over 3 months in almost half of the sample. Of note, no post-acute side effects emerged during the follow-up observation. The most frequent causes of drop-out from this study included major modifications in therapeutic regimen (30%) and poor adherence to follow-up visits (17%).

Conclusions

In this mid-term, open, follow-up study, tDCS showed mixed results. Further controlled studies are urgently needed to assess its effects beyond the acute phase.
A conceptual framework for improving well-being in people with a diagnosis of psychosis
Authors: Schrank B. , Riches S. , Bird V. , Murray J. , Tylee A. , Slade M.
Published: August 2013

Background.

Well-being is important for people with severe mental illness, such as psychosis. So far, no clear concept of well-being exists for this client group. A recent systematic review and narrative synthesis developed a static framework of well-being components. The present study aims to validate the static framework and to illuminate the processes by which well-being is experienced by people with psychosis.

Methods.

Semi-structured interviews were conducted with 23 service users with psychosis exploring their experience of well-being. Thematic analysis was used to analyse the data employing techniques taken from grounded theory to enhance the rigour of the analysis. Respondent validation was undertaken with 13 of the 23 participants.

Results.

Three superordinate categories of well-being were identified: current sense of self; transition to enhanced sense of self and enhanced sense of self. In the dynamic process of improving well-being the current sense of self undergoes a transition to an enhanced sense of self. The four factors influencing the transition are consistent with the static framework of well-being, hence validating the static framework. In addition, we identified three determinants of current sense of self and seven indicators of enhanced sense of self, which represent the achievement of improved well-being.

Conclusions.

This study provides an empirically defensible framework for understanding well-being in terms of determinants, influences and indicators. The influences are targets for interventions to improve well-being, and the indicators are outcome domains to assess the effectiveness of services in supporting well-being.
Multilevel selection analysis of a microbial social trait
Authors: de Vargas Roditi Laura , Boyle Kerry E , Xavier Joao B
Published: August 2013

The study of microbial communities often leads to arguments for the evolution of cooperation due to group benefits. However, multilevel selection models caution against the uncritical assumption that group benefits will lead to the evolution of cooperation. We analyze a microbial social trait to precisely define the conditions favoring cooperation. We combine the multilevel partition of the Price equation with a laboratory model system: swarming in Pseudomonas aeruginosa. We parameterize a population dynamics model using competition experiments where we manipulate expression, and therefore the cost‐to‐benefit ratio of swarming cooperation. Our analysis shows that multilevel selection can favor costly swarming cooperation because it causes population expansion. However, due to high costs and diminishing returns constitutive cooperation can only be favored by natural selection when relatedness is high. Regulated expression of cooperative genes is a more robust strategy because it provides the benefits of swarming expansion without the high cost or the diminishing returns. Our analysis supports the key prediction that strong group selection does not necessarily mean that microbial cooperation will always emerge.
Physical impairments of monitoring trails in all optical transparent networks
Authors: Hosszu Éva , Moghaddam Ehsan Sarvghad , Tapolcai János , Mazroa Dániel
Published: August 2013

In recent years, following the deployment of wavelength division multiplexing networks, fault detection and localisation has become a challenging issue in networks with high reliability. Optical layer monitoring schemes based on monitoring trails (m ‐trail) are considered an efficient way to localise a single fault unambiguously in all‐optical networks. In spite of the extensive work on the m ‐trail concept, the issue has not been validated from the feasibility point of view. Previous works on the m ‐trail monitoring scheme have focused mainly on algorithm design for minimising the number of monitors, however, none of them have observed that length limitations should be considered as well. The authors investigate the physical constraints of launching m ‐trails, mainly focusing on the maximum length that each m ‐trail may have and describe an algorithm that solves the length constrained m ‐trail formulation problem. Numerous simulations were implemented in a physical layer simulator for observing qualitative parameters in different m ‐trail lengths. The authors propose 15 000 km as a length limit for each m ‐trail for out‐of‐band monitoring. Finally, an algorithmic solution is provided for monitoring trail design problem satisfying these physical constraints.
Topographically induced internal solitary waves in a pycnocline: Secondary generation and selection criteria
Authors: Dossmann Y. , Auclair F. , Paci A.
Published: August 2013

Geophysical flows support the propagation of stable nonlinear internal waves (internal solitary waves or ISWs) with complex generation mechanisms. At least two regimes of ISWs generation in the pycnocline, both involving the interaction between a tidal flow and the bottom topography, are known in the ocean. They can either be directly induced above topographies (primary generation) or by a topographic internal wave beam impinging on the pycnocline. This “secondary generation” process is the subject-matter of the present study. The present work relies on direct numerical simulations of an academic configuration inspired by oceanic observations. It aims at describing the different steps involved in the secondary generation process. To mimic the oceanic case, the internal wave beam is emitted from the topography at the bottom of the flow. First, the linear scattering of the internal wave beam at the pycnocline is studied in a linear configuration. Increasing the forcing amplitude leads to the generation of steep isopycnal troughs in the pycnocline, at the locations of the internal wave beam impacts. The dynamics of these troughs is studied in details, which permits to associate them with propagating ISW2s that emerge from the second normal mode. Finally, the evolution of the structure of normal modes 2 and 3 with respect to the pycnocline strength, as well as the role played by the topography, is analyzed. This study is a step to complete and unify previous independent analytical studies of the secondary generation process.
A stigmatic ultraviolet-visible monochromator for use with a high brightness laser driven plasma light source
Authors: Feng Jun , Nasiatka J. , Wong Jared , Chen Xumin , Hidalgo Sergio , Vecchione T. , Zhu H. , Javier Palomares F. , Padmore H. A.
Published: August 2013

Laser driven plasma light sources offer highly intense output in the UV-visible region combined with a source size as small as 100 μm. In order to effectively use the small source size in high brightness applications, a stigmatic monochromator and focusing system must be used. Here we describe a simple brightness preserving optical system that should be useful across a broad range of applications. The output flux of this system is between 6 × 1011 ph/s and 4 × 1012 ph/s with a spectra resolution of 1.7 nm and field spot size of 0.1 mm from the UV to the VIS spectra range.
Tokamak halo currents
Authors: Boozer Allen H.
Published: August 2013

A halo current flows for part of its path through the plasma edge and for part through the chamber walls and can be as large as tenths of the plasma current. The primary interest in halo currents is the large force that they can exert on machine components. Two discordant constraints are central to the theory: (1) Halo currents must produce the magnetic field distribution required to maintain plasma force balance—a distribution that depends on the two angular coordinates of a torus. (2) Halo currents must flow along the magnetic field lines in the plasma, which implies a dependence on a linear combination of the two angular coordinates—only one angular coordinate is free. The physics basis of these two constraints is explained as is their application to the calculation of the properties of halo currents, such as their broad toroidal spectrum. Existing codes could be used to (1) provide detailed comparisons with experiments to validate that the critical elements of physics are adequately included, (2) allow more complete predictions for future machines such as ITER, and (3) design shunts and resistive elements to ensure halo currents follow paths that are the least damaging to the machine. The physics of halo currents implies that it may be possible to feedback stabilize resistive wall modes beyond the ideal-wall limit.
Wave function methods for fractional electrons
Authors: Steinmann Stephan N. , Yang Weitao
Published: August 2013

Determining accurate chemical potentials is of considerable interest in various chemical and physical contexts: from small molecular charge-transfer complexes to bandgap in bulk materials such as semi-conductors. Chemical potentials are typically evaluated either by density functional theory, or, alternatively, by computationally more intensive Greens function based GW computations. To calculate chemical potentials, the ground state energy needs to be defined for fractional charges. We thus explore an extension of wave function theories to fractional charges, and investigate the ionization potential and electron affinity as the derivatives of the energy with respect to the electron number. The ultimate aim is to access the chemical potential of correlated wave function methods without the need of explicitly changing the numbers of electrons, making the approach readily applicable to bulk materials. We find that even though second order perturbation theory reduces the fractional charge error considerably compared to Hartree-Fock and standard density functionals, higher order perturbation theory is more accurate and coupled-cluster approaches are even more robust, provided the electrons are bound at the Hartree-Fock level. The success of post-HF approaches to improve over HF relies on two equally important aspects: the integer values are more accurate and the Coulomb correlation between the fractionally occupied orbital and all others improves the straight line behavior significantly as identified by a correction to Hartree-Fock. Our description of fractional electrons is also applicable to fractional spins, illustrating the ability of coupled-cluster singles and doubles to deal with two degenerate fractionally occupied orbitals, but its inadequacy for three and more fractional spins, which occur, for instance, for spherical atoms and when dissociating double bonds. Our approach explores the realm of typical wave function methods that are applied mostly in molecular chemistry, but become available to the solid state community and offer the advantage of an integrated approach: fundamental gap, relative energies, and optimal geometries can be obtained at the same level.
A Lagrange multiplier approach for excited state properties through intermediate Hamiltonian formulation of Fock space multireference coupled-cluster theory
Authors: Gupta Jitendra , Vaval Nayana , Pal Sourav
Published: August 2013

In this paper, we present a formulation based on Lagrange multiplier approach for efficient evaluation of excited state energy derivatives in Fock space coupled cluster theory within the intermediate Hamiltonian framework. The formulation is applied to derive the explicit generic expressions up to second order energy derivatives for [1, 1] sector of Fock space with singles and doubles approximation. Its advantage, efficiency, and interconnection in comparison to the Lagrange multiplier approach in traditional formulation of Fock space, which is built on the concept of Bloch equation based effective Hamiltonian, has been discussed. Computational strategy for their implementation has also been discussed in some detail.
Nonlinear plasma wave in magnetized plasmas
Authors: Bulanov Sergei V. , Zh. Esirkepov Timur , Kando Masaki , Koga James K. , Hosokai Tomonao , Zhidkov Alexei G. , Kodama Ryosuke
Published: August 2013

Nonlinear axisymmetric cylindrical plasma oscillations in magnetized collisionless plasmas are a model for the electron fluid collapse on the axis behind an ultrashort relativisically intense laser pulse exciting a plasma wake wave. We present an analytical description of the strongly nonlinear oscillations showing that the magnetic field prevents closing of the cavity formed behind the laser pulse. This effect is demonstrated with 3D PIC simulations of the laser-plasma interaction. An analysis of the betatron oscillations of fast electrons in the presence of the magnetic field reveals a characteristic “Four-Ray Star” pattern.