bluuebunny/crossref_metadata_2025 huggingface dataset:
Fair Isn't Always Equal: Constituency Population and the Quality of Representation in Canada
Authors: Thomas Paul E.J. , Loewen Peter John , MacKenzie Michael K.
Published: May 2013

Abstract.Is there a conflict between the principles of representation by population and the representation of communities of interest? In Canada, the legal requirement to design electoral districts based on pre-existing regions and communities of interest has produced large discrepancies in district populations. Several authors claim that this situation has a deleterious effect on the representational experiences of those citizens living in more populous districts. This paper examines whether the population of an electoral district affects the quality of political representation in that district. We first present survey data characterizing the relationship between constituency population and citizens' reported satisfaction with democracy and contact with politicians and parties. We then present audit experimental evidence from Canada demonstrating that the helpfulness of politicians towards citizens is not conditioned on constituency population. Our data indicate that constituency population has no clear impact on the quality of representational experiences in Canada, suggesting that it is possible to ensure the effective representation of communities of interest without harming the overall quality of Canadian democracy.

Résumé.Y a-t-il un conflit entre les principes de représentation par personne et de représentation de communautés d'intérêts? Au Canada, des écarts importants entre la population de certaines circonscriptions électorales résultent de l'obligation légale de les délimiter en tenant compte des régions et des communautés d'intérêts préexistantes. Plusieurs auteurs soutiennent que cette situation entraîne des effets néfastes sur la représentation vécue par les citoyens qui habitent les circonscriptions les plus populeuses. Dans cet article, nous vérifions si la taille de la population influence la qualité de la représentation politique dans une circonscription électorale. Nous présentons d'abord des données d'enquête sur la relation entre la taille de la population d'une circonscription et (i) la satisfaction des citoyens à l'égard de la démocratie, (ii) leurs contacts avec les politiciens et (iii) les communications qu'ils reçoivent des politiciens et des partis. Puis, nous présentons des données d'une expérience menée au Canada qui indiquent que la propension des politiciens à aider les citoyens n'est pas influencée par la taille de la population de leur circonscription. Nos résultats indiquent que la taille de la population d'une circonscription n'a pas d'effet clair sur la qualité de la représentation au Canada, suggérant ainsi qu'il est possible d'assurer la représentation efficace des communautés d'intérêts sans nécessairement nuire à la qualité globale de la démocratie canadienne.
The Oligocene–Miocene tectonic evolution of the northern Outer Carpathian fold-and-thrust belt: insights from compression-and-rotation analogue modelling experiments
Authors: RAUCH MARTA
Published: May 2013

This paper presents the different analogue scenarios of the tectonic evolution of the northern Outer Carpathians (i.e. the Western and northern Eastern Outer Carpathians) which formed as an accretionary wedge in front of the East Alpine–Carpathian–Pannonian (ALCAPA) block during Oligocene–Miocene times. Currently, this fold-and-thrust belt forms an arc which is asymmetrically convex to the north and wider in its eastern part. Palaeomagnetic investigations have suggested that the rocks of the arc underwent counter-clockwise rotation along almost the whole arc, which is difficult to explain as an effect of simple indentation of the triangular indenter. In this case two branches of the arc should be rotated in the opposite directions. The structural evolution of the Western Outer Carpathians is characterized by superposition of two successive tectonic shortening events directed N–S and NE–SW. The results of the presented analogue modelling suggest that two scenarios of the geodynamic evolution of the studied belt could explain the occurrence of such differently oriented shortening events: (1) two phases of differently directed indentation (first to the N, then to the NE) and (2) indenter movement to the NE with simultaneous counter-clockwise rotation. However, the experiment in which the moving indenter is simultaneously rotated produces the most suitable model. The counter-clockwise rotation of the material is only possible in front of both sides of the convex indenter in this model. The results of the analogue modelling also prove that rotation of the ALCAPA block started after formation of the Magura nappe (the innermost nappe of the Western Outer Carpathians).
Do Stock Markets Catch the Flu?
Authors: McTier Brian C. , Tse Yiuman , Wald John K.
Published: May 2013

We examine the impact of influenza on stock markets. For the United States, a higher incidence of flu is associated with decreased trading, decreased volatility, decreased returns, and higher bid-ask spreads. Consistent with the flu affecting institutional investors and market makers, the decrease in trading activity and volatility is primarily driven by the incidence of influenza in the greater New York City area. However, the effect of the flu on bid-ask spreads and returns is related to the incidence of flu nationally. International data confirm our findings of a decrease in trading activity and returns when flu incidence is high.
Debt Maturity and Asymmetric Information: Evidence from Default Risk Changes
Authors: Goyal Vidhan K. , Wang Wei
Published: May 2013

Asymmetric information models suggest that a borrower’s choice of debt maturity depends on its private information about its default probabilities, that is, borrowers with favorable information prefer short-term debt while those with unfavorable information prefer long-term debt. We test this implication by tracing the evolution of debt issuers’ default risk following debt issuances. We find that short-term debt issuance leads to a decline inborrowers’ asset volatility and an increase in their distance to default. The opposite is true for long-term debt issues. The results suggest that borrowers’ private information about their default risk is an important determinant of their debt maturity choices.
Anatomical variation of the extracranial course of the optic nerve in the floor of the sphenoid sinus: first reported case
Authors: Girguis-Bucher A , Schlegel-Wagner C
Published: May 2013

Objective:

We report a unique case of anatomical variation of the extracranial course of the optic nerve running in the floor of the sphenoid sinus.

Method:

Clinical and radiological findings are presented.

Results:

A 39-year-old woman with Turner syndrome presented with severe headache associated with visual disturbances. Magnetic resonance imaging revealed a mass presumed to be a sella meningioma. Computed tomography of the paranasal sinuses was undertaken to help plan surgical removal via an endoscopic trans-sphenoidal approach; this scan revealed an atypical extracranial course of the optic nerve, running in the floor of the sphenoid sinus.
Methicillin-resistant Staphylococcus aureus bacteraemia associated with Lemierre's syndrome: case report and literature review
Authors: Kizhner V , Samara G , Panesar R , Krespi Y P
Published: May 2013

Background:

Community-acquired methicillin-resistant Staphylococcus aureus is a growing health concern. Lemierre's syndrome is a septic jugular thrombophlebitis that primarily affects young adults. This paper aimed to identify a possible sub-group of Lemierre's syndrome cases associated with community-acquired methicillin-resistant Staphylococcus aureus.

Method:

This paper reports the case of a 16-year-old male who was admitted for increasing fever, tachycardia, tachypnoea and neck pain. The patient was diagnosed with methicillin-resistant Staphylococcus aureus bacteraemia associated with Lemierre's syndrome. A literature review was subsequently conducted.

Results:

Following intravenous antibiotic treatment and the sterilisation of blood cultures, the patient improved. The literature review indicated a rise in the past 2 years of Lemierre's syndrome associated with methicillin-resistant Staphylococcus aureus among patients less than 18 years of age.

Conclusion:

Community-acquired methicillin-resistant Staphylococcus aureus bacteraemia can lead to pulmonary sequelae. When it is associated with pharyngitis, nasopharyngitis or parapharyngeal lymphadenitis, the affected patient may be predisposed to Lemierre's syndrome. As bacterial carriage is predominantly nasal, pharyngitis may not be present. Methicillin-resistant Staphylococcus aureus should be included as an offending bacterium where there is suspicion of Lemierre's syndrome. It is unclear whether anticoagulation alters the course of the bacterium, and surgery is probably contraindicated.
‘The Greatest of Equalisers’: A Critical Review of International Organisations’ Views on Early Childhood Care and Education
Authors: MORABITO CHRISTIAN , VANDENBROECK MICHEL , ROOSE RUDI
Published: May 2013

There is a large consensus among international organisations (e.g., United Nations and the World Bank) in considering Early Childhood Care and Education a prominent policy to equalise opportunities. Moreover, it is common opinion that interventions in early childhood aiming at equalising ‘opportunities’ rather than ‘outcomes’ will overcome political dissent. These two claims draw upon a particular interpretation of the work of contemporary egalitarian philosophers, as well as a number of studies in both developed and developing countries, finding higher benefits for disadvantaged children. Despite the tradition of analysing welfare provision from an equality perspective, the shift towards early childhood education as an equality policy has not yet fully been analysed. We critically examine the consensus advocated by international organisations regarding Early Childhood Care and Education as key to ‘levelling the playing field’ and suggest that the first claim (early childhood as greatest equaliser) should be considered with caution. We also argue that the alleged consensus on this claim may lead to a depoliticisation of social policy.
Vertebrate pollination of the endemic Trochetia granulata (Malvaceae) on Réunion
Authors: Le Péchon Timothée , Sanchez Mickaël , Humeau Laurence , Gigord Luc D.B. , Zhang Li-Bing
Published: May 2013

The pollination ecology and breeding system of Trochetia granulata (Malvaceae), an endemic tree species from Réunion were studied. In 2010–2011, compatibility studies were conducted on a total of 154 flowers from 35 different individuals using three different hand pollination treatments: (a) autofertility, (b) self-pollination and (c) cross-pollination. During the period, we also studied the pollination ecology of T. granulata. During 48 h of video recordings, we tracked flower visits to T. granulata in six different sites and studied the behaviour of the visitors. The results from the hand-cross experiments show that T. granulata is self-compatible (60.8% fruit set) but cannot produce fruit (5.4% fruit set) without the visit of a pollen vector. During surveys, four different visitors were reported: the introduced honey bee (Apis mellifera), two endemic species of white-eye (Zosterops borbonicus borbonicus and Z. olivaceus) and the endemic Réunion day gecko (Phelsuma borbonica). This study documented a new case of vertebrate-pollination by lizard and birds in an insular context. These interactions might be linked to several uncommon floral traits of Trochetia species.
Luminescent properties of Eu3+-doped SmBa3B9O18
Authors: He Ming , Zhang Z.H. , Zhu Y.Z. , Tang Y.G. , Song Z.
Published: May 2013

Eu3+-doped SmBa3B9O18 luminescent materials were synthesized by high temperature solid state reactions. The structure and photoluminescence properties of Sm(1−x)EuxBa3B9O18 (x = 0.2, 0.4, and 0.6) were investigated by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, and photoluminescence spectra. The results show that doping of Eu3+ ions does not change the structure of SmBa3B9O18. The luminescence is mainly the characteristic Eu3+ ion luminescence. No concentration quenching processes occur with the increment of Eu3+ concentration. The work implies that SmBa3B9O18 is a potential host material and europium-doped SmBa3B9O18 may find application in display and optical devices.
Power and music in Cairo: Azbakiyya
Authors: MESTYAN ADAM
Published: May 2013

In this article, the origins of the modern metropolis are reconsidered, using the example of Cairo within its Ottoman and global context. I argue that Cairo's Azbakiyya Garden served as a central ground for fashioning a dynastic capital throughout the nineteenth century. This argument sheds new light on the politics of Khedive Ismail, who introduced a new state representation through urban planning and music theatre. The social history of music in Azbakiyya proves that, instead of functioning as an example of colonial division, Cairo encompassed competing conceptions of class, taste and power.
Classifying psychotropic drugs by mode of action and not by target disorder
Authors: Stahl Stephen M.
Published: May 2013

ISSUE:Psychotropic drugs are traditionally classified by the first disorder they are proven to target (eg, as antidepressants or antipsychotics). However, these names are becoming increasingly confusing, as many drugs have multiple therapeutic actions. A more rational nomenclature categorizes psychotropic drugs by their pharmacologic mode of action.
Patient's experiences of involuntary hospital admission and treatment: A review of qualitative studies
Authors: Katsakou Christina , Priebe Stefan
Published: May 2013

Aims - This study aimed to explore psychiatric patients' experiences of involuntary admission and treatment by reviewing qualitative studies. Method - Qualitative studies investigating patients' experiences of involuntary treatment were identified. Relevant databases were searched and authors were contacted. Thematic analysis was applied for the synthesis of emerging issues. Results - Five studies fulfilled the inclusion criteria. The main areas that appear to be of importance are: patients' perceived autonomy and participation in decisions for themselves, their feeling of whether or not they are being cared for and their sense of identity. In these areas both negative and positive consequences from involuntary admission were mentioned. However, methodological weaknesses were also found, such as small sample sizes. Furthermore, it is not described whether these themes are mentioned by all participants as negative and positive aspects of their experience or whether they reflect views supported by distinct groups. Conclusions - Although the perceived impact of involuntary treatment is fairly clearly described, differences between distinct patient groups are not examined. Future research should investigate such differences in order to inform relevant policy decisions for particular groups.

Declaration of Interest: None.
Non-Western immigrant children have lower 25-hydroxyvitamin D than children from Western families
Authors: Omand Jessica A , Darling Pauline B , Parkin Patricia C , Birken Catherine S , Khovratovich Marina , Thorpe Kevin E , Carsley Sarah , DeGroot Julie , Maguire Jonathon L ,   on behalf of the TARGet Kids! Collaboration
Published: May 2013

Objective

To determine if children aged 1–6 years from non-Western immigrant families have lower serum 25-hydroxyvitamin D (25(OH)D) levels than children from Western-born families and examine which factors influence this relationship.

Design

Cross-sectional study.

Setting

Toronto, Canada.

Subjects

Healthy children (n1540) recruited through the TARGet Kids! practice-based research network. Serum 25(OH)D concentrations of non-Western immigrants were compared with those of children from Western-born families. Children from non-Western immigrant families were defined as those born, or their parents were born, outside a Western country. Univariate and multiple linear regression analyses were used to identify factors which might influence this relationship.

Results

Median age was 36 months, 51 % were male, 86 % had ‘light’ skin pigmentation, 55 % took vitamin D supplements, mean cow's milk intake was 1·8 cups/d and 27 % were non-Western immigrants. Median serum 25(OH)D concentration was 83 nmol/l, with 5 % having 25(OH)D < 50 nmol/l. Univariable analysis revealed that non-Western immigrant children had serum 25(OH)D lower by 4 (95 % CI 1·3, 8·0) nmol/l (P= 0·006) and increased odds of 25(OH)D < 50 nmol/l (OR = 1·9; 95 % CI 1·3, 2·9). After adjustment for known vitamin D determinants the observed difference attenuated to 0·04 (95 % CI −4·8, 4·8) nmol/l (P= 0·99), with higher cow's milk intake (P< 0·0001), vitamin D supplementation (P< 0·0001), summer season (P= 0·008) and increased age (P= 0·04) being statistically significant covariates. Vitamin D supplementation was the strongest explanatory factor of the observed difference.

Conclusions

There is an association between non-Western immigration and lower 25(OH)D in early childhood. This difference appears related to known vitamin D determinants, primarily vitamin D supplementation, representing opportunities for intervention.
Characterizing lunch meals served and consumed by pre-school children in Head Start
Authors: Nicklas Theresa A , Liu Yan , Stuff Janice E , Fisher Jennifer O , Mendoza Jason A , O'Neil Carol E
Published: May 2013

Objective

To examine the variability of food portions served and consumed by African-American and Hispanic-American pre-school children attending Head Start.

Design

Cross-sectional.

Setting

Food consumption by pre-schoolers (n796) enrolled in sixteen Head Start centres in Houston, Texas (51 % boys, 42 % African-American, mean age 4 years) were assessed during 3 d of lunch meals using digital photography. Descriptive statistics and multilevel regression models, adjusting for classroom and school clustering effects, were determined.

Subjects

Head Start pre-schoolers aged 3–5 years.

Results

Mean amount served was 2428 kJ (580 kcal) and 572 g. Mean intake was 1421 kJ (339 kcal) and 331 g: 20 % protein, 46 % carbohydrate and 34 % fat. Plate waste was 43 % (range: 38 % (fruit) to 61 % (vegetables)). Mean CV of food served was 29 %: 33 % for entrées, 44 % for vegetables, 60 % for fruit and 76 % for starches. Mean CV of food consumed was 46 %: 58 % for entrées, 86 % for fruit, 96 % for vegetables and 111 % for starches. Total gram amount of food served was positively correlated with consumption (r= 0·43,P< 0·001).

Conclusions

Plate waste and variation in amounts served and consumed were substantial; amounts served were associated with amounts consumed. Large portion sizes may contribute to paediatric obesity by promoting excessive intake at meals. Understanding factors influencing portion sizes provides insight about specific intervention strategies that can be used in obesity prevention programmes.
Associations between access to farmers’ markets and supermarkets, shopping patterns, fruit and vegetable consumption and health indicators among women of reproductive age in eastern North Carolina, USA
Authors: Jilcott Pitts Stephanie B , Wu Qiang , McGuirt Jared T , Crawford Thomas W , Keyserling Thomas C , Ammerman Alice S
Published: May 2013

Objective

We examined associations between access to food venues (farmers’ markets and supermarkets), shopping patterns, fruit and vegetable consumption and health indicators among women of reproductive age in eastern North Carolina, USA.

Design

Access to food venues was measured using a Geographic Information System incorporating distance, seasonality and business hours, to quantify access to farmers’ markets. Produce consumption was assessed by self-report of eating five or more fruits and vegetables daily. BMI and blood pressure were assessed by clinical measurements. Poisson regression with robust variance was used for dichotomous outcomes and multiple linear regression was used for continuous outcomes. As the study occurred in a university town and university students are likely to have different shopping patterns from non-students, we stratified analyses by student status.

Setting

Eastern North Carolina.

Subjects

Low-income women of reproductive age (18–44 years) with valid address information accessing family planning services at a local health department (n 400).

Results

Over a quarter reported ever shopping at farmers’ markets (114/400). A larger percentage of women who shopped at farmers’ markets consumed five or more fruits and vegetables daily (42·1 %) than those who did not (24·0 %; P < 0·001). The mean objectively measured distance to the farmers’ markets where women reported shopping was 11·4 (sd 9·0) km (7·1 (sd 5·6) miles), while the mean distance to the farmers’ market closest to the residence was 4·0 (sd 3·7) km (2·5 (sd 2·3) miles).

Conclusions

Among non-students, those who shopped at farmers’ markets were more likely to consume five or more servings of fruits and vegetables daily. Future research should further explore potential health benefits of farmers’ markets.
Design, modeling and characterization of MMIC integrated cascode cell for compact Ku-band power amplifiers
Authors: Déchansiaud A. , Sommet R. , Reveyrand T. , Bouw D. , Chang C. , Camiade M. , Deborgies F. , Quéré R.
Published: May 2013

This paper reports on the design of a new power cell dedicated to Ku-band power amplifier (PA) applications. This cell called “integrated cascode” has been designed in order to propose a strong decrease in terms of circuit size for PA. The technology used relies on 0.25-μm GaAs pseudomorphic high electron mobility transistors (PHEMT) of United Monolithic Semiconductors (UMS) foundry. A distributed approach is proposed in order to model this power cell. The challenge consists of obtaining, with a better shape factor (ratio between the vertical and horizontal sizes of the transistor), the same performances than a single transistor with the same gate width. In order to design a 2W amplifier, we have used two 12 × 100 μm transistors. Cascode vertical size is 413 μm whereas a transistor with the same gate width exhibits a vertical size of 790 μm. Therefore, the shape factor is nearly one as compared to a shape factor of 4 for a classical parallel architecture. This new device allows us to decrease the Monolithic microwave integrated circuit amplifier area of 40% compared to amplifier based on single transistors.
Sigma-1 receptor agonist PRE084 is protective against mutant huntingtin-induced cell degeneration: involvement of calpastatin and the NF-κB pathway
Authors: Hyrskyluoto A , Pulli I , Törnqvist K , Huu Ho T , Korhonen L , Lindholm D
Published: May 2013

Alterations in mitochondria and increased oxidative stress are associated with the disease progression in Huntington’s disease (HD). Endoplasmic reticulum (ER) stress and oxidative damage are linked through the close communication between the ER and mitochondria. Sigma-1 receptor (Sig-1R) is a chaperone protein in the ER that is involved in ER stress regulation, but little is known about its role in HD or the mechanisms for cell protection. Here we show that the Sig-1R agonist, PRE084 increases cell survival and counteracts the deleterious effects caused by N-terminal mutant huntingtin proteins in neuronal PC6.3 cells. Particularly, PRE084 increased the levels of cellular antioxidants by activating the NF-κB pathway that is compromised by the expression of mutant huntingtin proteins. These results show that the Sig-1R agonist has beneficial effects in models of HD and that compounds affecting the Sig-1R may be promising targets for future drug development in HD.
Addressable and unidirectional energy transfer along a DNA three-way junction programmed by pyrrole-imidazole polyamides
Authors: Su Wu , Bagshaw Clive R. , Burley Glenn A.
Published: May 2013

We describe a photonic waveguide where FRET is routed uni-directionally along a double-stranded DNA track. The efficiency of FRET is modulated by the supramolecular control of fluorophores along double-stranded DNA using fluorophore-tethered Pyrrole-Imidazole polyamides (PAs). We show that uni-directional FRET is enhanced by the complete assembly of each of the constituent parts, resulting in the selective routing of light along simple DNA duplexes as well as a three-way junction (3WJ).
Living Radical Polymerizations with Organic Catalysts
Authors: Goto A. , Tsujii Y. , Kaji H.
Published: May 2013

This chapter introduces fundamental features of two new families of living radical polymerizations that use organic catalysts for reversible activation. The polymerizations are based on new reversible activation mechanisms, reversible chain transfer (RT) and reversible complexation (RC), and have been proposed to be termed RT catalyzed polymerization (RTCP) and RC mediated polymerization (RCMP). The catalysts are germanium, tin, phosphorus, nitrogen, oxygen, and carbon-centered molecules. They include such common compounds as phosphites (P), imides and amines (N), phenols (O) and dienes (C). Low-polydispersity polymers were obtained in the homopolymerizations and random and block copolymerizations of styrene, methyl methacrylate, acrylonitrile, and several functional styrenics and methacrylates. Attractive features of the catalysts include their good polydispersity controllability, good tolerance to functional groups, inexpensiveness, low toxicity, and ease of handling (robustness). The backgrounds, performances, and kinetic features of RTCP and RCMP are described.
Atom Transfer Radical Polymerization (ATRP)
Authors: Tsarevsky Nicolay V. , Matyjaszewski Krzysztof
Published: May 2013

Atom transfer radical polymerization (ATRP) is a catalytic process mediated by a redox-active transition metal complex able to abstract homolytically a halogen atom from an alkyl halide in a reversible fashion. The mechanistic understanding of ATRP is crucial and enables the rational selection of reaction components and conditions needed for the synthesis of well-defined polymers. This chapter provides an overview of the parameters that determine the activity and performance of the ATRP catalyst, i.e., its ability to control the polymerization and also its propensity to participate in undesired side complexation or redox reactions with reaction components (monomer, polymer, propagating radicals, solvent, and other additives). The effects of the central atom or ion of the catalyst, the ligand, the transferable halogen atom, and the reaction solvent can be described quantitatively by formally splitting the overall atom transfer equilibrium into contributing reactions, including the homolysis of a carbon–halogen bond, reduction of the halogen atom to a halide ion (electron affinity), oxidation of the lower oxidation state metal complex (activator),and formation of the radical deactivator via coordination of a halide anion to the higher oxidation state metal complex (halidophilicity). Additionally, the factors that are responsible for the activity of alkyl halides as radical sources, including structure of the alkyl group and the nature of the halide are also discussed.
Nucleotides and nucleic acids; oligo‐ and polynucleotides
Authors: Loakes David
Published: May 2013

As in previous years, modified oligonucleotides continue to attract much research. The scope for modifying oligonucleotides is quite broad, nucleobase, sugar or the internucleotide linkage, and a combination of each. This review covers literature for 2011 ealing with modified oligonucleotides, though unlike previous years the sections on aptamers and ribozymes, and nucleic structures are excluded, but will be dealt with in the next volume.
Localized orbitals from basis sets augmented with diffuse functions
Authors: Høyvik Ida-Marie , Jørgensen Poul
Published: May 2013

Orbital localization of occupied and virtual Hartree–Fock orbitals generated from basis sets augmented with diffuse functions is performed using the Pipek–Mezey, Boys, powers of the second central moment, and powers of the fourth central moment localizations. The locality of the obtained orbital sets are presented in terms of second and fourth moment orbital spreads. The results show that both local occupied and virtual orbitals may be obtained when using powers of the second central moment and powers of the fourth central moment localizations, while the Pipek–Mezey and Boys localizations fail to produce sets of local virtual orbitals. The locality of the fourth central moment virtual orbitals exhibits a locality similar to the locality of a Boys localization for non-augmented basis sets.
Characterization and performance of a field aligned ion cyclotron range of frequency antenna in Alcator C-Mod
Authors: Wukitch S. J. , Garrett M. L. , Ochoukov R. , Terry J. L. , Hubbard A. , Labombard B. , Lau C. , Lin Y. , Lipschultz B. , Miller D. , Reinke M. L. , Whyte D. ,   Alcator C-Mod Team
Published: May 2013

Ion cyclotron range of frequency (ICRF) heating is expected to provide auxiliary heating for ITER and future fusion reactors where high Z metallic plasma facing components (PFCs) are being considered. Impurity contamination linked to ICRF antenna operation remains a major challenge particularly for devices with high Z metallic PFCs. Here, we report on an experimental investigation to test whether a field aligned (FA) antenna can reduce impurity contamination and impurity sources. We compare the modification of the scrape of layer (SOL) plasma potential of the FA antenna to a conventional, toroidally aligned (TA) antenna, in order to explore the underlying physics governing impurity contamination linked to ICRF heating. The FA antenna is a 4-strap ICRF antenna where the current straps and antenna enclosure sides are perpendicular to the total magnetic field while the Faraday screen rods are parallel to the total magnetic field. In principle, alignment with respect to the total magnetic field minimizes integrated E|| (electric field along a magnetic field line) via symmetry. A finite element method RF antenna model coupled to a cold plasma model verifies that the integrated E|| should be reduced for all antenna phases. Monopole phasing in particular is expected to have the lowest integrated E||. Consistent with expectations, we observed that the impurity contamination and impurity source at the FA antenna are reduced compared to the TA antenna. In both L and H-mode discharges, the radiated power is 20%–30% lower for a FA-antenna heated discharge than a discharge heated with the TA-antennas. However, inconsistent with expectations, we observe RF induced plasma potentials (via gas-puff imaging and emissive probes to be nearly identical for FA and TA antennas when operated in dipole phasing). Moreover, the highest levels of RF-induced plasma potentials are observed using monopole phasing with the FA antenna. Thus, while impurity contamination and sources are indeed reduced with the FA antenna configuration, the mechanism determining the SOL plasma potential in the presence of ICRF and its impact on impurity contamination and sources remains to be understood.
Symplectic quantum mechanics and Chern-Simons gauge theory. II. Mapping tori of tori
Authors: Jeffrey Lisa C.
Published: May 2013

We compute the semiclassical formulas for the partition functions obtained using two different Lagrangians: the Chern-Simons functional and the symplectic action functional.
Electrically conductive (Mg0.2Ti0.8)O underlayer to grow FePt-based perpendicular recording media on glass substrates
Authors: Varaprasad B. S. D. Ch. S. , Takahashi Y. K. , Ajan Antony , Hono K.
Published: May 2013

We have explored a new electrically conductive underlayer material to grow (001) textured L10-FePt films on glass substrates for potential application in ultrahigh density magnetic recording media. We found (Mg0.2Ti0.8)O (MTO) polycrystalline film grows with a strong (001) texture on Cr buffer layer, which induces strong (001) texture of L10-FePt polycrystalline and granular films. Strong perpendicular anisotropy of 3.8 × 107 erg/cm3 and coercivity of 15 kOe of a FePt-C film has been demonstrated using the MTO underlayer on glass substrates.
Pseudo Jahn-Teller coupling in trioxides XO3(0,1,−1) with 22 and 23 valence electrons
Authors: Grein Friedrich
Published: May 2013

D3h and C2v geometries and energies, vertical excitation energies, as well as minimal energy paths as function of the O1(z)-X-O2 angle α were obtained for XO3(0,1,−1) (X = B, Al, Ga; C, Si, Ge; N, P, As; S, Se) molecules and ions with 22 and 23 valence electrons (VE), using density functional theory (DFT), coupled cluster with single and double substitutions with noniterative triple excitations (CCSD(T)), equation of motion (EOM)-CCSD, time-dependent DFT, and multi-reference configuration interaction methods. It is shown that pseudo Jahn-Teller (PJT) coupling increases as the central atom X becomes heavier, due to decreases in excitation energies. As is well known for CO3, the excited 1E′ states of the 22 VE systems SiO3, GeO3; ${\rm NO}_3 ^ +$ NO 3+, PO3+, AsO3+; BO3−, AlO3−, GaO3− have strong vibronic coupling with the 1A1′ ground state via the e′ vibrational modes, leading to a C2v minimum around α = 145°. For first and second row X atoms, there is an additional D3h minimum (α = 120°). Interacting excited states have minima around 135°. In the 23 VE systems CO3−, SiO3−; NO3, PO3; SO3+, coupling of the excited 2E′ with the 2A2′ ground state via the e′ mode does not generate a C2v state. Minima of interacting excited states are close to 120°. However, due to very strong PJT coupling, a double-well potential is predicted for GeO3−, AsO3, and SeO3+, with a saddle point at D3h symmetry. Interaction of the b2 highest occupied molecular orbital with the b2 lowest unoccupied molecular orbital, both oxygen lone pair molecular orbitals, is seen as the reason for the C2v stabilization of 22 VE molecules.
Instantaneous normal mode analysis of the vibrational relaxation of the amide I mode of alanine dipeptide in water
Authors: Farag Marwa H. , Zúñiga José , Requena Alberto , Bastida Adolfo
Published: May 2013

Nonequilibrium Molecular Dynamics (MD) simulations coupled to instantaneous normal modes (INMs) analysis are used to study the vibrational relaxation of the acetyl and amino-end amide I modes of the alanine dipeptide (AlaD) molecule dissolved in water (D2O). The INMs are assigned in terms of the equilibrium normal modes using the Effective Atomic Min-Cost algorithm as adapted to make use of the outputs of standard MD packages, a method which is well suited for the description of flexible molecules. The relaxation energy curves of both amide I modes show multiexponential decays, in good agreement with the experimental findings. It is found that ∼85%–90% of the energy relaxes through intramolecular vibrational redistribution. The main relaxation pathways are also identified. The rate at which energy is transferred into the solvent is similar for the acetyl-end and amino-end amide I modes. The conformational changes occurring during relaxation are investigated, showing that the populations of the alpha and beta region conformers are altered by energy transfer in such a way that it takes 15 ps for the equilibrium conformational populations to be recovered after the initial excitation of the AlaD molecule.
The phase behavior of linear and partially flexible hard-sphere chain fluids and the solubility of hard spheres in hard-sphere chain fluids
Authors: Oyarzún Bernardo , van Westen Thijs , Vlugt Thijs J. H.
Published: May 2013

The liquid crystal phase behavior of linear and partially flexible hard-sphere chain fluids and the solubility of hard spheres in hard-sphere chain fluids are studied by constant pressure Monte Carlo simulations. An extensive study on the phase behavior of linear fluids with a length of 7, 8, 9, 10, 11, 12, 13, 14, 15, and 20 beads is carried out. The phase behavior of partially flexible fluids with a total length of 8, 10, 14, and 15 beads and with different lengths for the linear part is also determined. A precise description of the reduced pressure and of the packing fraction change at the isotropic-nematic coexistence was achieved by performing long simulation runs. For linear fluids, a maximum in the isotropic to nematic packing fraction change is observed for a chain length of 15 beads. The infinite dilution solubility of hard spheres in linear and partially flexible hard-sphere chain fluids is calculated by the Widom test-particle insertion method. To identify the effect of chain connectivity and molecular anisotropy on free volume, solubility is expressed relative to that of hard spheres in a hard sphere fluid at same packing fraction as relative Henry's law constants. A linear relationship between relative Henry's law constants and packing fraction is observed for all linear fluids. Furthermore, this linearity is independent of liquid crystal ordering and seems to be independent of chain length for linear chains of 10 beads and longer. The same linear relationship was observed for the solubility of hard spheres in nematic forming partially flexible fluids for packing fractions up to a value slightly higher than the nematic packing fraction at the isotropic-nematic coexistence. At higher packing fractions, the small flexibility of these fluids seems to improve solubility in comparison with the linear fluids.
On filtering in the viscous-convective subrange for turbulent mixing of high Schmidt number passive scalars
Authors: Verma Siddhartha , Blanquart G.
Published: May 2013

In the present work, we investigate the possibility of performing velocity-resolved, scalar-filtered (VR-SF) numerical simulations of turbulent mixing of high Schmidt number scalars, by using a Large Eddy Simulation (LES)-type filter in the viscous-convective subrange. The only requirement for this technique is the large scale separation between the Kolmogorov and Batchelor length scales, which is a direct outcome of the high Schmidt number of the scalar. The present a priori analysis using high fidelity direct numerical simulation data leads to two main observations. First, the missing triadic interactions between (resolved) velocity and (filtered-out) scalar modes in the viscous-convective subrange do not affect directly the large scales. Second, the magnitude of the subgrid term is shown to be extremely small, which makes it particularly susceptible to numerical errors associated with the scalar transport scheme. A posteriori tests indicate that upwinded schemes, generally used for LES in complicated geometries, are sufficiently dissipative to overwhelm any contribution from the subgrid term. This renders the subgrid term superfluous, and as a result, VR-SF simulations run without subgrid scalar flux models are able to preserve large scale transport characteristics with remarkable accuracy.
Superconductivity in Al-substituted Ba8Si46 clathrates
Authors: Li Yang , Garcia Jose , Chen Ning , Liu Lihua , Li Feng , Wei Yuping , Bi Shanli , Cao Guohui , Feng Z. S.
Published: May 2013

There is a great deal of interest vested in the superconductivity of Si clathrate compounds with sp3 network, in which the structure is dominated by strong covalent bonds among silicon atoms, rather than the metallic bonding that is more typical of traditional superconductors. A joint experimental and theoretical investigation of superconductivity in Al-substituted type-I silicon clathrates is reported. Samples of the general formula Ba8Si46−xAlx, with different values of x were prepared. With an increase in the Al composition, the superconducting transition temperature TC was observed to decrease systematically. The resistivity measurement revealed that Ba8Si42Al4 is superconductive with transition temperature at TC = 5.5 K. The magnetic measurements showed that the bulk superconducting Ba8Si42Al4 is a type II superconductor. For x = 6 sample Ba8Si40Al6, the superconducting transition was observed down to TC = 4.7 K which pointed to a strong suppression of superconductivity with increasing Al content as compared with TC = 8 K for Ba8Si46. Suppression of superconductivity can be attributed primarily to a decrease in the density of states at the Fermi level, caused by reduced integrity of the sp3 hybridized networks as well as the lowering of carrier concentration. These results corroborated by first-principles calculations showed that Al substitution results in a large decrease of the electronic density of states at the Fermi level, which also explains the decreased superconducting critical temperature within the BCS framework. The work provided a comprehensive understanding of the doping effect on superconductivity of clathrates.
In situ modification of chromatography adsorbents using cold atmospheric pressure plasmas
Authors: Olszewski P. , Willett T. C. , Theodosiou E. , Thomas O. R. T. , Walsh J. L.
Published: May 2013

Efficient manufacturing of increasingly sophisticated biopharmaceuticals requires the development of new breeds of chromatographic materials featuring two or more layers, with each layer affording different functions. This letter reports the in situ modification of a commercial beaded anion exchange adsorbent using atmospheric pressure plasma generated within gas bubbles. The results show that exposure to He-O2 plasma in this way yields significant reductions in the surface binding of plasmid DNA to the adsorbent exterior, with minimal loss of core protein binding capacity; thus, a bi-layered chromatography material exhibiting both size excluding and anion exchange functionalities within the same bead is produced.
Dispersionless optical activity in metamaterials
Authors: Hannam Kirsty , Powell David A. , Shadrivov Ilya V. , Kivshar Yuri S.
Published: May 2013

We introduce a chiral metamaterial with strong, non-resonant optical activity and very low polarization ellipticity. We achieve this by combining a meta-atom and its complementary structure into a meta-molecule, resulting in the coupling of magnetic and electric dipole responses. In contrast to either a pair of crosses or complementary crosses, this structure has low dispersion in the optical activity at the transmission resonance. We also study the excitation mechanism in this structure and optimize the optical activity through changing the twist angle.
Improved photoelectrochemical performance of Cu(In,Ga)Se2 thin films prepared by pulsed electrodeposition
Authors: Mandati Sreekanth , Sarada Bulusu V. , Dey Suhash R. , Joshi Shrikant V.
Published: May 2013

Solar cells based on polycrystalline Cu(In,Ga)Se2 absorber layers have yielded the highest conversion efficiency among all the thin-film technologies. CIGS thin-films possess large optical absorption coefficient (≈105 cm−1) and a suitable bandgap of ≈ 1.20 eV for an ideal stoichiometry of CuIn0.7Ga0.3Se2. In the present study, Direct Current (DC) and Pulsed Current (PC) electrodeposition techniques are employed to obtain the near ideal stoichiometric CIGS thin-films on a Mo foil using a two electrode system at a constant potential. Deposited films are annealed at 550 °C under Ar atmosphere. Characterization of the annealed CIGS films is performed using SEM-energy dispersive X-ray spectroscopy, X-ray diffraction, Raman spectroscopy, and photoelectrochemistry to study the morphology, stoichiometry, phase constitution, and the photoelectrochemical response. PC deposition offered suitable manipulation of various parameters, which has helped in obtaining a better quality stoichiometric single phase chalcopyrite structured CIGS thin films with the elimination of unwanted secondary phases like Cu2−xSe. An improved photoelectrochemical performance, characteristic of a p-type semiconductor, is observed for the PC deposited CIGS films.
Effect of embedding silica nanoparticles and voids in the performance of c-Si solar cells
Authors: Das Sonali , Kundu Avra , Saha Hiranmay , Datta Swapan K.
Published: May 2013

The effect of embedding nanoentities (silica and voids) on the optical and electrical performance of Si solar cells has been investigated in an attempt to decouple the Anti-Reflection (AR) properties of the standard nitride coated Solar Cells (SCs) and the scattering properties of the nanoentities. The decoupling will ensure the use of the scattering properties of the nanoentities without disturbing the optimized reflection characteristics of a standard SC. Lumerical® Finite Difference Time Domain Solutions software has been used to simulate the optical performance of solar cells after embedding nanoentities in the emitter region. Simulation results indicate that total decoupling of the AR properties and the scattering properties of the nanoentities is not obtained. Electrical performance evaluation of the system reveals a substantial relative improvement (1.7%) in the efficiency of thick (200 μm) SCs which further increases for thin (2 μm) film cells (23%) when 100 nm radius nanovoids having 30% area coverage are embedded at a depth of 200 nm from the silicon surface. The relative improvement is compromised if the changes in the material parameters due to embedding nanoentities are taken in to account.
Spontaneous assembly of ordered atomic wires with a long interwire distance on a stepped atomic template
Authors: Shin B. G. , Kim M. K. , Oh D.-H. , Song I. , Lee J. H. , Woo S. H. , Park C.-Y. , Ahn J. R.
Published: May 2013

Indium atomic wires with a long interwire distance of 5.73 nm were ordered spontaneously at room temperature on a stepped atomic template using a Si(557) surface. The long interwire distance is very interesting because, in general, interwire interactions are needed to order atomic wires in such a way that ordered atomic wires have a short interwire distance of just a few Å. The Si(557) surface is composed of four steps, i.e., one (111) step and three (112) steps, with a very similar local structure to each other. However, mobile indium atoms at room temperature were adsorbed specifically onto the second Si(112) step while maintaining the overall structure of the stepped atomic template, as observed by scanning tunneling microscopy, which results in the ordered atomic wires with the long interwire distance. This was supported by first-principles calculations.
Note: Readout of a micromechanical magnetometer for the ITER fusion reactor
Authors: Rimminen H. , Kyynäräinen J.
Published: May 2013

We present readout instrumentation for a MEMS magnetometer, placed 30 m away from the MEMS element. This is particularly useful when sensing is performed in high-radiation environment, where the semiconductors in the readout cannot survive. High bandwidth transimpedance amplifiers are used to cancel the cable capacitances of several nanofarads. A frequency doubling readout scheme is used for crosstalk elimination. Signal-to-noise ratio in the range of 60 dB was achieved and with sub-percent nonlinearity. The presented instrument is intended for the steady-state magnetic field measurements in the ITER fusion reactor.
Intrinsic origin of rubber-like behavior in thermoelastic alloys
Authors: Cui Yanguang , Wan Jianfeng , Man Jiao , Zhang Jihua , Rong Yonghua
Published: May 2013

The evolution of polytwinned martensitic variants, which accompanies changes in various energies under applied stress, is investigated using a 3-dimensional phase-field simulation. The intrinsic origin of the rubber-like behavior (RLB) in a thermoelastic alloy is revealed as the disappearance of one variant during loading and its reappearance during unloading, whereas long “stress aging” enhances martensite stabilization. The applied stress and elastic strain energies drive the respective microstructural evolution and its reversal. This intrinsic origin of the RLB cannot be excluded in thermoelastic alloys for which the RLB can be explained by “symmetry conforming-short range order” principle.