bluuebunny/crossref_metadata_2025 huggingface dataset:
High Temperature Thermal Gradient Interaction Chromatography (HT‐TGIC) for Microstructure Analysis of Polyolefins
Authors: Cong Rongjuan , deGroot A. Willem , Parrott Al , Yau Wallace , Hazlitt Lonnie , Brown Ray , Cheatham Michael , Miller Matthew D. , Zhou Zhe
Published: February 2012

Summary: High temperature thermal gradient interaction chromatography (HT‐TGIC) is a newly developed technique to analyze comonomer distributions in polyolefins. This paper documents the key differences between crystallization elution fractionation (CEF) and HT‐TGIC, and the advantages of using multiple detectors in HT‐TGIC to provide comprehensive microstructure characterization. A demonstration of the technique using a specifically designed blend, provides comprehensive data in less than 1.5 hours of analysis time by HT‐TGIC. This paper also reports that HT‐TGIC has excellent short term repeatability.
Advanced Characterization of Propylene‐Based Copolymers and Olefin Block Copolymers
Authors: Shan Colin Li Pi , Miller Matt , Lee Dean , Zhou Zhe
Published: February 2012

Summary: The newly developed interactive separation of polyolefins by high temperature liquid chromatography (HTLC) provides new information about the chemical composition distribution of polyolefin elastomers. The technique has the advantage of being quantitative in its separation, and has high resolution for the separation of polyolefins by their chemical composition without influence by cocrystallization. Chemical composition distributions can be determined for individual polymers and blends which contain the full range of comonomer typically present in polyethylene and poylypropylene homopolymers, semi‐crystalline copolymers, and amorphous copolymers. HTLC analysis in combination with the other fractionation techniques, such as DSC, TREF, NMR, and xylene fractionation, can be used to estimate the amount of olefin block copolymer present in a block composite produced by chain shuttling catalysis.
A case study of missed approach of aircraft due to tailwind associated with thunderstorms
Authors: Tse S. M. , Chan P. W. , Wong W. K.
Published: February 2012

Two aircraft had to conduct missed approaches in the overnight period of 8–9 September 2010 due to intense thunderstorm activity at the Hong Kong International Airport (HKIA). The missed approach event is studied in detail in this paper using the available flight data and other meteorological measurements. It appeared that the missed approaches were attributable to strong tailwind associated with the downdraft of the thunderstorm. Timely wind shear/microburst alerts had been provided to the pilots in this case based on the measurements from a Terminal Doppler Weather Radar (TDWR) and ground‐based anemometer measurements at HKIA. The nowcasting and forecasting aspects for such an event are also discussed. The Aviation Thunderstorm Nowcasting System (ATNS) developed by the Hong Kong Observatory (HKO) is found to provide adequate nowcasting of thunderstorm activity for this particular case and the aviation weather forecasters could be alerted of such intense convective weather at the airport more than half an hour ahead. On the forecasting side, the mesoscale meteorological model used by HKO may provide an indication of the strong tailwind associated with the thunderstorm at 6–7 h ahead, though the exact timing of the tailwind at the airport may be delayed by a couple of hours compared with the actual situation. Using the model the downdraft of the thunderstorm in this event is examined in detail.
Describing seasonal variability in the distribution of daily effective temperatures for 1985–2009 compared to 1904–1984 for De Bilt, Holland
Authors: Underwood F. M.
Published: February 2012

This paper proposes a method for describing the distribution of observed temperatures on any day of the year such that the distribution and summary statistics of interest derived from the distribution vary smoothly through the year. The method removes the noise inherent in calculating summary statistics directly from the data thus easing comparisons of distributions and summary statistics between different periods. The method is demonstrated using daily effective temperatures (DET) derived from observations of temperature and wind speed at De Bilt, Holland. Distributions and summary statistics are obtained from 1985 to 2009 and compared to the period 1904–1984. A two‐stage process first obtains parameters of a theoretical probability distribution, in this case the generalized extreme value (GEV) distribution, which describes the distribution of DET on any day of the year. Second, linear models describe seasonal variation in the parameters. Model predictions provide parameters of the GEV distribution, and therefore summary statistics, that vary smoothly through the year. There is evidence of an increasing mean temperature, a decrease in the variability in temperatures mainly in the winter and more positive skew, more warm days, in the summer. In the winter, the 2% point, the value below which 2% of observations are expected to fall, has risen by 1.2 °C, in the summer the 98% point has risen by 0.8 °C. Medians have risen by 1.1 and 0.9 °C in winter and summer, respectively. The method can be used to describe distributions of future climate projections and other climate variables. Further extensions to the methodology are suggested.
Hartmann–Hahn 2D‐map to optimize the RAMP–CPMAS NMR experiment for pharmaceutical materials
Authors: Suzuki Kazuko , Martineau Charlotte , Fink Gerhard , Steuernagel Stefan , Taulelle Francis
Published: February 2012

Cross polarization–magic angle spinning (CPMAS) is the most used experiment for solid‐state NMR measurements in the pharmaceutical industry, with the well‐known variant RAMP–CPMAS its dominant implementation. The experimental work presented in this contribution focuses on the entangled effects of the main parameters of such an experiment. The shape of the RAMP–CP pulse has been considered as well as the contact time duration, and a particular attention also has been devoted to the radio‐frequency (RF) field inhomogeneity. 13 C CPMAS NMR spectra have been recorded with a systematic variation of 13 C and 1H constant radiofrequency field pair values and represented as a Hartmann‐Hahn matching two‐dimensional map. Such a map yields a rational overview of the intricate optimal conditions necessary to achieve an efficient CP magnetization transfer. The map also highlights the effects of sweeping the RF by the RAMP–CP pulse on the number of Hartmann–Hahn matches crossed and how RF field inhomogeneity helps in increasing the CP efficiency by using a larger fraction of the sample. In the light of the results, strategies for optimal RAMP–CPMAS measurements are suggested, which lead to a much higher efficiency than constant amplitude CP experiment. Copyright © 2012 John Wiley & Sons, Ltd.
Diffuse instabilities with transition to localization in loose granular materials
Authors: Wan Richard , Pinheiro Mauricio , Daouadji Ali , Jrad Mohamad , Darve Félix
Published: February 2012

This paper is concerned with diffuse and other ensuing failure modes in geomaterials when tested under homogeneous states of shearing in various loading programs and drainage conditions. Material instability is indeed the basic property that accounts for the instability of an initially homogeneous deformation field leading to diffuse failure and strain localization in geomaterials. The former is normally characterized by a runaway type of failure accompanied with a sudden and violent collapse of the material in the absence of any localization phenomena. Against this backdrop, we present a brief overview of material instability in elastoplastic solids where one finds a rich source of theoretical concepts including bifurcation, strain localization, diffuse failure and second‐order work, as well as a considerable body of experiments. Some compelling laboratory experimental studies of material instability with focus to diffuse failure are then presented and interpreted based on the second‐order work. Finally, various material instability analyses using an elastoplastic constitutive and a general finite element analysis of the above‐mentioned laboratory experimental tests are presented as a boundary value problem. It is shown that instability can be captured from otherwise uniform stress, density and hydraulic states, whereas uniform deviatoric loads are being applied on the external boundaries of a specimen. Although the numerical simulations reproduce well the laboratory experimental results, they also highlight the hierarchy of failure modes where localization phenomena emerge in the post‐bifurcation regime as a result of a degradation of homogeneity starting from a diffuse mode signalled by a zero second‐order work. Copyright © 2012 John Wiley & Sons, Ltd.
A novel method for simultaneous 3D B1 and T1 mapping: the method of slopes (MoS)
Authors: Chavez Sofia , Stanisz Greg J.
Published: February 2012

A novel three‐dimensional simultaneous B1 and T1 mapping method is introduced: the method of slopes (MoS). The linearity of the spoiled gradient recalled echo (SPGR) signal vs flip angle relation is exploited: B1 mapping is achieved by a two‐point extrapolation to signal null with a correction scheme while T1 mapping uses the slopes of the SPGR signal vs flip angle curves near the origin and near the signal null. This new method improves upon the existing variable flip angle (VFA) T1‐mapping method in that (i) consistency between B1 and T1 maps is ensured (ii) the sampling scheme is T1‐independent (iii) the noise bias and singularity, associated with using a linear form for the SPGR signal equation, is eliminated by using the full equation. The method is shown to yield accurate and robust results via simulations. Initial estimates of B1 and T1 values are obtained from three data points via simple computations and straight line approximations. Initial estimates of B1 values, for a range of values, are shown to be accurate due to the proposed B1 correction scheme. The accuracy and robustness of T1 values is achieved via a non‐linear fitting algorithm which includes a fourth data point sampled at high SNR. The MoS was validated by comparing resulting B1 and T1 maps with those obtained using other standard methods. Finally, the ability to obtain brain B1 and T1 maps using the MoS was demonstrated by in vivo experiments. The MoS is expected to perform well on other motion‐free anatomical regions as well. Copyright © 2012 John Wiley & Sons, Ltd.
Long‐term hygrothermal response of perforated GFRP plates with/without application of constant external loading
Authors: Eslami Shiva , Taheri‐Behrooz Fathollah , Taheri Farid
Published: February 2012

The use of glass fiber‐reinforced polymer (GFRP) composites is increasingly being considered in various applications where the composite is subjected to harsh hot and humid conditions. Although information on the performance of GFRP under hot and humid conditions is available, the characteristics and the response of perforated GFRP under such conditions have not been fully explored. In this article, the response of perforated GFRP plates subject to hot and humid environment is examined. The applicability and accuracy of Fick's model for establishing the amount of moisture absorption by such composites is examined, and an improved model is proposed. The article also demonstrates the influence of constant external loading on such perforated GFRP while undergoing conditioning in a hot and humid environment. Moreover, since the strength and stiffness of composites can be significantly affected by harsh environments, the degradation in the strength and stiffness of the perforated GFRP as a function of time is established. A new model is proposed wherein degradation of the strength of such perforated composites may be established as a function of time and geometric entities. The model can also account for the influence of the applied loading. POLYM. COMPOS. 2012. © 2012 Society of Plastics Engineers
Microstructural, mechanical, and thermal characteristics of recycled cellulose fiber‐halloysite‐epoxy hybrid nanocomposites
Authors: Alamri H. , Low I. M.
Published: February 2012

Epoxy hybrid‐nanocomposites reinforced with recycled cellulose fibers (RCF) and halloysite nanotubes (HNTs) have been fabricated and investigated. The dispersion of HNTs was studied by synchrotron radiation diffraction (SRD) and transmission electron microscopy (TEM). The influences of RCF/HNTs dispersion on the mechanical properties and thermal properties of these composites have been characterized in terms of flexural strength, flexural modulus, fracture toughness, impact toughness, impact strength, and thermogravimetric analysis. The fracture surface morphology and toughness mechanisms were investigated by SEM. Results indicated that mechanical properties increased because of the addition of HNTs into the epoxy matrix. Flexural strength, flexural modulus, fracture toughness, and impact toughness increased by 20.8, 72.8, 56.5, and 25.0%, respectively, at 1 wt% HNTs load. The presence of RCF dramatically enhanced flexural strength, fracture toughness, impact strength, and impact toughness of the composites by 160%, 350%, 444%, and 263%, respectively. However, adding HNTs to RCF/epoxy showed only slight enhancements in flexural strength and fracture toughness. The inclusion of 5 wt% HNTs into RCF/epoxy ecocomposites increased the impact toughness by 27.6%. The presence of either HNTs or RCF accelerated the thermal degradation of neat epoxy. However, at high temperature, samples reinforced with RCF and HNTs displayed better thermal stability with increased char residue than neat resin. POLYM. COMPOS. 2012. © 2012 Society of Plastics Engineers
Poly(urethane‐co‐vinyl imidazole)/graphene nanocomposites
Authors: Cai Zhixin , Liu Li , Zheng Zhen , Wang Xinling
Published: February 2012

Poly(urethane‐co‐vinyl imidazole) (PUVI)/graphene nanocomposites were facilely prepared by a kind of noncovalent way. Herein, the 1‐vinylimidazole acted as dispersion agent as well as monomer, graphene was uniformly dispersed in the copolymer matrix without obviously agglomeration. A significant enhancement of mechanical and thermal properties of the PUVI/graphene nanocomposites were obtained at low graphene loading; specifically, a 147% improvement of tensile strength, a nearly 10 times increase of elastic modulus and a 12°C enhancement of thermal decomposition temperature were achieved at a graphene loading of 1.5 wt%. Moreover, the volume resistivity of the PUVI/graphene nanocomposites decreased by an order of magnitude after adding 0.5 wt% graphene, demonstrating an obvious change in the electrical property of the nanocomposites prepared. POLYM. COMPOS. 2012. © 2012 Society of Plastics Engineers
Ethylene‐vinyl acetate copolymer/multiwalled carbon nanotube/organoclay nanocomposites
Authors: Seol Sung‐Mok , Kim Gue‐Hyun
Published: February 2012

Ethylene‐vinyl acetate copolymer (EVA) was melt‐mixed with multiwalled carbon nanotubes (MWCNTs) and organoclays, and the effects of simultaneous use of organoclays and MWCNTs on the surface resistivity and tensile properties of EVA nanocomposites were investigated. The surface resistivity of EVA/MWCNT nanocomposite with 1 phr of MWCNT is out of our measurement range (above 1012 Ω/square). With increasing content of organoclay from 0 to 3 phr, the surface resistivity of the EVA/MWCNT/organoclay nanocomposites with 1 phr MWCNT remains out of our measurement range. However, the surface resistivity of the nanocomposite decreases to 106 Ω/square with addition of 5 phr organoclay. The tensile properties of EVA/MWCNT/organoclay nanocomposites with 1 phr MWCNT and 5 phr organocaly are similar to those of EVA/MWCNT nanocomposites with 5 phr MWCNT except tensile modulus. POLYM. COMPOS. 2012. © 2012 Society of Plastics Engineers
Advanced PERC and PERL production cells with 20.3% record efficiency for standard commercial p‐type silicon wafers
Authors: Wang Zhenjiao , Han Peiyu , Lu Hongyan , Qian Hongqiang , Chen Liping , Meng Qinglei , Tang Ning , Gao Feng , Jiang Yongfei , Wu Jiaqi , Wu Wenjuan , Zhu Haidong , Ji Jingjia , Shi Zhengrong , Sugianto Adeline , Mai Ly , Hallam Brett , Wenham Stuart
Published: February 2012

Following intensive research and development, Suntech Power has successfully commercialised its Pluto technology with 0.5 GW annual production capacity, delivering up to 10% performance advantage over conventional screen‐printed cells. The next generation of Pluto involves the development of improved rear surface design based on the design features of passivated emitter and rear locally diffused cells. Cells with an average efficiency over 20% were fabricated on 155 cm2 commercial‐grade p‐type wafers using mass‐manufacturing processes and equipment, with the highest single‐cell efficiency independently confirmed at 20.3%. This is believed to be a record efficiency for this wafer type. Further optimisation work on contact pattern and rear surface passivation suggests the potential for further efficiency increase approaching 23%. Copyright © 2012 John Wiley & Sons, Ltd.
Overview of an effective‐medium approach to the reflection and refraction of light at a turbid colloidal half‐space
Authors: Gutiérrez‐Reyes Edahí , García‐Valenzuela Augusto , Barrera Rubén G.
Published: February 2012

It has been recently shown that the effective electromagnetic bulk response of a dilute colloidal system, composed by a large collection of identical big spheres, located at random, is spatially dispersive (non‐local). Here, we extend this effective‐medium approach to the calculation of the reflection and transmission amplitudes of the same system but with a flat interface. We use an integral‐equation approach for the calculation of the average electric field. The integral equation is solved within the effective‐field approximation, by proposing a plane‐wave solution with effective parameters that are calculated by solving a set of consistency equations. We obtain explicit expressions for the transmission and reflection amplitudes as a function of the filling fraction, the radius of the inclusions and the angle of incidence. We show and discuss numerical results for a system of silver particles.
Stationary high‐field domains as tools to measure field‐dependent carrier densities and mobilities in CdS and work functions of blocking contacts
Authors: Böer Karl W.
Published: February 2012

It is shown that stationary high‐field domains that occur in the range of negative differential conductivity, can be used to clearly identify field‐quenched states in CdS. These are distinguished as cathode‐ and anode‐adjacent domains and permit an unambiguous determination of electron density and mobility as function of the electric field. The anode‐adjacent domain permits additional insight into the high‐field properties of CdS in a field range that is now stabilized in the pre‐breakdown range. Here one finds direct evidence, by using the spectral distribution of the photoconductivity within the domain, of inverting the CdS to p‐type either by more complete quenching or by hole injection from the anode. Both types of stationary domains are determined by the work function of blocking contacts and thereby permit a closer analysis of the contact/CdS interface by shifting the space charge region away from the cathode to the bulk‐side end of the domain. This allows a more precise determination of the dependence of the work function on the photoconductivity of the adjacent CdS. The field‐of‐direction (phase portrait) analysis of the time‐independent transport and Poisson equations allows a simple classification of the two types of stationary high‐field domains relating to the two singular points in the decreasing branch of the current–voltage characteristic. This permits a transparent discussion of the field distribution of these domains that can be directly observed by the Franz–Keldysh effect. Herewith the transition between cathode‐ to anode‐adjacent domains as a function of the applied voltage can be directly followed.
Synthesis and first‐principles calculations of the structural and electronic properties of type‐I clathrates Sr8Ga16SnxGe30 − x
Authors: Li D. C. , Fang L. , Deng S. K. , Kang K. Y. , Wei W. H. , Ruan H. B.
Published: February 2012

In the present work we report on the synthesis of type‐I clathrates Sr8Ga16SnxGe30 − x (0 ≤ x ≤ 12). To find out how the substitution of Sn for Ge affects structural stability and electronic structure, the structural and electronic properties for Sr8Ga16SnxGe30 − x (0 ≤ x ≤ 30) have been investigated by a first‐principles method based on the density‐functional theory (DFT). We found that the lattice constants of Sr8Ga16SnxGe30 − x series increase with increasing Sn content, which is consistent with X‐ray diffraction (XRD) results. Calculations indicate that the substitution of Sn for Ge leads to the change of the bulk modulus and the decrease of stability of the structure. It is found that these alloys are all indirect‐gap semiconductors and the bandgap decreases from about 0.36 eV in Sr8Ga16Ge30 to about 0.03 eV in Sr8Ga16Sn30 with increasing Sn content. The decrease of the bandgap is attributed to the increase of the free space for the Sr guest motion, which is accompanied by the guest's low‐energy modes and larger anharmonicity. These mean that an increase in the ratio of Sn‐to‐Ge can not only control the electrical properties of the materials, but also may reduce their thermal conductivity, suggesting that cage‐size tuning is one of the useful means to obtain high‐performance thermoelectric (TE) materials.
Concentration Dependent Effect of (−)‐Epicatechin on Na+/K+‐ATPase and Ca2+‐ATPase Inhibition Induced by Free Radicals in Hypertensive Patients: Comparison with L‐ascorbic Acid
Authors: Kumar Navneet , Kant Ruchi , Maurya Pawan Kumar , Rizvi Syed Ibrahim
Published: February 2012

Although the antioxidant properties of flavonoids are well documented, it is still unclear whether these effects are dependent on radical scavenging or iron chelating activities. Oxidative stress, a state of excessive reactive oxygen species (ROS) activity, is associated with vascular disease conditions such as hypertension. Both the anti‐ and pro‐oxidant effects of tea catechins have been implicated in the alterations of cellular functions that determine their chemoprotective and therapeutic potentials in health and diseases. The present study examined the concentration dependent (10−7 to 10−4 m) effects of (−)‐epicatechin and L‐ascorbic acid on Na+/K+‐ATPase and Ca2+‐ATPase activity in hypertensive patients and normal subjects. L‐ascorbic acid has been used as a positive control to compare the effect of (−)‐epicatechin. A significant (p < 0.0001) decrease in the activities of Na+/K+‐ATPase and Ca2+‐ATPase was observed in hypertensive patients compared with normal subjects. We report that (−)‐epicatechin shows a significant (p < 0.001) dose‐dependent protective effect against oxidative stress induced by tert‐butyl hydroperoxide (t‐BHP), which is manisfested as a decrease in the activity of erythrocyte Na+/K+‐ATPase and Ca2+‐ATPase, in hypertensive patients as well as normal subjects. The effect of L‐ascorbic acid was also significant (p < 0.001) and was comparable with that of (−)‐epicatechin. Copyright © 2012 John Wiley & Sons, Ltd.
Mastering crosscutting architectural decisions with aspects
Authors: Sant'Anna Claudio , Garcia Alessandro , Batista Thais , Rashid Awais
Published: February 2012

When reflecting upon driving system requirements such as security and availability, software architects often face decisions that have a broadly scoped impact on the software architecture. These decisions are the core of the architecting process because they typically have implications intertwined in a multitude of architectural elements and across multiple views. Without a modular representation and management of those crucial choices, architects cannot properly communicate, assess and reason about their crosscutting effects. The result is a number of architectural breakdowns, such as misinformed architectural evaluation, time‐consuming trade‐off analysis and unmanageable traceability. This paper presents an architectural documentation approach in which aspects are exploited as a natural way to capture widely‐scoped design decisions in a modular fashion. The approach consists of a simple high‐level notation to describe crosscutting decisions, and a supplementary language that allows architects to formally define how such architectural decisions affect the final architectural decomposition according to different views. On the basis of two case studies, we have systematically assessed to what extent our approach: (i) supports the description of heterogeneous forms of crosscutting architecture decisions, (ii) improves the support for architecture modularity analysis, and (iii) enhances upstream and downstream traceability of crosscutting architectural decisions. Copyright © 2012 John Wiley & Sons, Ltd.
Phase 1, open-label study of MEDI-547 in patients with relapsed or refractory solid tumors
Authors: Annunziata Christina M. , Kohn Elise C. , LoRusso Patricia , Houston Nicole D. , Coleman Robert L. , Buzoianu Manuela , Robbie Gabriel , Lechleider Robert
Published: February 2012

Background Targeting the cell-surface receptor EphA2, which is highly expressed in some solid tumors, is a novel approach for cancer therapy. We aimed to evaluate the safety profile, maximum tolerated dose (MTD), pharmacokinetics, and antitumor activity of MEDI-547, an antibody drug conjugate composed of the cytotoxic drug auristatin (toxin) linked to a human anti-EphA2 monoclonal antibody (1C1), in patients with solid tumors relapsed/refractory to standard therapy. Methods In this phase 1, open-label study with planned dose-escalation and dose-expansion cohorts, patients received a 1-h intravenous infusion of MEDI-547 (0.08 mg/kg) every 3 weeks. Results Six patients received 0.08 mg/kg; all discontinued treatment. Dose escalation was not pursued. The study was stopped before cohort 2 enrollment due to treatment-related bleeding and coagulation events (hemorrhage-related, n = 3; epistaxis, n = 2). Therefore, lower doses were not explored and an MTD could not be selected. The most frequently reported treatment-related adverse events (AEs) were increased liver enzymes, decreased hemoglobin, decreased appetite, and epistaxis. Three patients (50%) experienced treatment-related serious AEs, including conjunctival hemorrhage, pain (led to study drug discontinuation), liver disorder, and hemorrhage. Best response included progressive disease (n = 5; 83.3%) and stable disease (n = 1; 16.7%). Minimal or no dissociation of toxin from 1C1 conjugate occurred in the blood. Serum MEDI-547 concentrations decreased rapidly, ~70% by 3 days post-dose. No accumulation of MEDI-547 was observed at 0.08 mg/kg upon administration of a second dose 3 weeks following dose 1. Conclusions The safety profile of MEDI-547 does not support further clinical
investigation in patients with advanced solid tumors.
Thermal and Mechanical Characterization of Epoxy Resins (ELO and ESO) Cured with Anhydrides
Authors: Samper M. D. , Fombuena V. , Boronat T. , García‐Sanoguera D. , Balart R.
Published: February 2012

In this work we have developed polymeric materials from epoxidized vegetable oils in order to obtain materials with excellent mechanical properties for use as green matrix composites. Epoxidized soybean oil (ESO), epoxidized linseed oil (ELO) and different mixtures of the two oils were used to produce the polymers. Phthalic anhydride (17 mol%) and maleic anhydride (83 mol%) which has a eutectic reaction temperature of 48 °C were used as crosslinking agents while benzyl dimethyl amine (BDMA) and ethylene glycol were used as the catalyst and initiator, respectively. The results showed that samples 100ELO and 80ELO20ESO could be used as a matrix in green composites because they demonstrated good mechanical properties.
CONJUGACY CLASS SIZES OF CERTAIN DIRECT PRODUCTS
Authors: CASOLO CARLO , TOMBARI ELISA MARIA
Published: February 2012

We consider finite groups in which, for all primes p, the p-part of the length of any conjugacy class is trivial or fixed. We obtain a full description in the case in which for each prime divisor p of the order of the group there exists a noncentral conjugacy class of p-power size.
Electoral competition, factionalism, and persistent party dominance in Botswana
Authors: Poteete Amy R.
Published: February 2012

The Botswana Democratic Party (BDP) has maintained a super-majority in the National Assembly for over forty years despite increasingly competitive elections. Several factors contribute to the BDP's continued legislative dominance, including features of the electoral system, fragmentation of the party system, and obstacles to strategic voting behaviour. Factional competition has played a particularly important role. Botswana's political institutions encourage factional competition, and factionalism interacts with the electoral system to hinder consolidation of the party system. Botswana's experience underlines the importance of internal party dynamics and their interaction with features of the electoral and party system in enabling the persistence of legislative dominance in competitive electoral systems.
Morality plays and money matters: towards a situated understanding of the politics of homosexuality in Uganda
Authors: Sadgrove Joanna , Vanderbeck Robert M. , Andersson Johan , Valentine Gill , Ward Kevin
Published: February 2012

Since the drafting of Uganda's anti-homosexuality bill in 2009, considerable attention has been paid both in Uganda and across the African continent to the political and social significance of homosexual behaviour and identity. However, current debates have not adequately explained how and why anti-homosexual rhetoric has been able to gain such popular purchase within Uganda. In order to move beyond reductive representations of an innate African homophobia, we argue that it is necessary to recognise the deep imbrication of sexuality, family life, procreation and material exchange in Uganda, as well as the ways in which elite actors (including government officials, the media and religious leaders) are able to manipulate social anxieties to further particular ends. We employ a discourse analysis of reporting in the state-owned newspaperNew Vision, first considering how the issue of homosexuality has been represented in relation to wider discourses regarding threats to public morality and national sovereignty. Then, through fieldwork undertaken in Uganda in 2009, we explore three key themes that offer deeper insights into the seeming resonance of this popular rhetoric about homosexuality: constructions of the family, the nature of societal morality, and understandings about reciprocity and material exchange in contemporary Ugandan society.
Cultural translation of mobile telephones: mediation of strained communication among Ethiopian married couples
Authors: Kenaw Setargew
Published: February 2012

Primarily aiming to highlight and exemplify how a technology can be socially and culturally appropriated, this article draws attention to the role of mobile phone communication in straining relations between married couples on the basis of material from Ethiopia. The findings show that mobile phone-mediated interactions between spouses are filled with monitoring and controlling activities, expressed in such forms as checking call logs, text messages, making casual calls, and switching-off phones, leading to highly strained relations that may result in the marital relation as a whole falling apart. These findings show how a technology can actively shape or influence interactions, and reveal interactions that might otherwise be concealed.
The ecological role of native and introduced species in the diet of the pumaPuma concolorin southern Patagonia
Authors: Zanón Martínez Juan Ignacio , Travaini Alejandro , Zapata Sonia , Procopio Diego , Santillán Miguel Ángel
Published: February 2012

There is evidence for the ecological extinction of the native prey of the pumaPuma concolorin north-western Argentine Patagonia. In this study we examine whether this is also the case in southern Patagonia. From 2004 to 2007 we examined the puma’s diet in three protected areas and two sheep ranches in Santa Cruz province. A total of 282 puma scats were analysed. In two of the protected areas and in the ranches 60–74% of the puma’s diet was native prey. Prey species were primarily guanaco Lama guanicoe, followed by Patagonian mara Dolichotis patagonum, lesser rhea Pterocnemia pennata pennata, Patagonian pichi Zaedyus pichiy and Magellanic penguin Spheniscus magellanicus. In the third protected area the main prey was the European hareLepus europaeus. Our results show a clear difference in the diet of the puma in southern compared to north-western Patagonia. Large native herbivores (i.e. guanaco and lesser rhea) maintain their role as the main prey species for the puma in southern Patagonia. We suggest, therefore, that native prey could be restored to those areas of Argentine Patagonia, such as the north-west, where they are currently ecologically extinct. Facilitating native species recovery and/or restoration and applying more rigorous controls to prevent the introduction of potential alien prey species of the puma both, within and outside protected areas, needs to be evaluated as a regional strategy.
Water funds and payments for ecosystem services: practice learns from theory and theory can learn from practice
Authors: Goldman-Benner Rebecca L. , Benitez Silvia , Boucher Timothy , Calvache Alejandro , Daily Gretchen , Kareiva Peter , Kroeger Timm , Ramos Aurelio
Published: February 2012

Payments for ecosystem services (PES) are emerging worldwide as important mechanisms to align investments in human and natural well-being. PES projects are often defined as voluntary transactions where well-defined environmental/ecosystem services (or land uses likely to secure those services) are bought by a minimum of one service buyer, from a minimum of one service provider, if and only if the service provider continuously secures service provision (conditionality). Further criteria of PES include limiting additional objectives and ensuring that payments reward behaviour that would otherwise not occur (additionality). Together these best practices for PES are increasingly accepted as the most efficient means to achieve desired outcomes and are guiding funding for PES projects. We used a series of water funds (watershed-oriented PES projects based on a trust fund model) to examine how theoretical best practices could inform and improve practice and also how theory could learn from practical efforts. We conclude that thoughtful consideration is required when evaluating the promise of a PES approach against a theoretical ideal. We found that requiring conditionality may limit the use of creative finance mechanisms such as trust funds that can provide long-term benefits for conservation and human well-being, and that requiring additionality can exclude benefits from social diffusion and result in the inefficient targeting of PES funds. Finally, public–private partnerships in water funds lead to multiple additional/side objectives but partnerships are likely to lower transaction costs and provide transparent, long-term landscape-scale watershed management.
Optimization design for a jumping leg robot based on generalized inertia ellipsoid
Authors: Yao Jianjun , Yang Qi , Gao Shuang , Hu Shenghai
Published: February 2012

The isotropy of the generalized inertia ellipsoid is an evaluation index that can measure dynamic performance of a robot. This has significance in motion planning and design of a jumping robot. The generalized inertia of a jumping robot is analyzed. The generalized inertia tensor and the generalized inertia ellipsoid (GIE) are derived from the kinetic energy of the robot mechanism. From the viewpoint of geometrical shape change of the GIE, nonlinear characteristics of a jumping robot are analyzed. With the goal of minimizing nonlinear effects during its movement, the mechanism parameters of a jumping robot are optimized by adopting isotropy of the generalized inertia ellipsoid as its objective function. Example results demonstrate the efficiency and validity of the proposed optimization method.
The representation theory of C*-algebras associated to groupoids
Authors: CLARK LISA ORLOFF , AN HUEF ASTRID
Published: February 2012

Let E be a second-countable, locally compact, Hausdorff groupoid equipped with an action of such that G: = E/ is a principal groupoid with Haar system λ. The twisted groupoid C*-algebra C*(E; G, λ) is a quotient of the C*-algebra of E obtained by completing the space of -equivariant functions on E. We show that C*(E; G, λ) is postliminal if and only if the orbit space of G is T0 and that C*(E; G, λ) is liminal if and only if the orbit space is T1. We also show that C*(E; G, λ) has bounded trace if and only if G is integrable and that C*(E; G, λ) is a Fell algebra if and only if G is Cartan.

Let be a second-countable, locally compact, Hausdorff groupoid with Haar system λ and continuously varying, abelian isotropy groups. Let be the isotropy groupoid and : = /. Using the results about twisted groupoid C*-algebras, we show that the C*-algebra C*(, λ) has bounded trace if and only if is integrable and that C*(, λ) is a Fell algebra if and only if is Cartan. We illustrate our theorems with examples of groupoids associated to directed graphs.
POST-AVICENNAN LOGICIANS ON THE SUBJECT MATTER OF LOGIC: SOME THIRTEENTH- AND FOURTEENTH-CENTURY DISCUSSIONS
Authors: El-Rouayheb Khaled
Published: February 2012

In the thirteenth century, the influential logician Afḍal al-Dīn al-Khūnajī (d. 1248) departed from the Avicennan view that the subject matter of logic is “second intentions”. For al-Khūnajī, the subject matter of logic is “the objects of conception and assent”. His departure elicited intense and sometimes abstruse discussions in the course of subsequent centuries. Prominent supporters of Khūnajī's view on the subject matter of logic included Kātibī (d. 1277), Ibn Wāṣil (d. 1298) and Taftāzānī (d. 1390). Defenders of Avicenna's view included Ṭūsī (d. 1274), Samarqandī (d. 1303) and Quṭb al-Dīn al-Rāzī (d. 1365). This article presents the outline of the development of this discussion down to the end of the fourteenth century and attempts to reconstruct the major arguments of both sides.
A chronology of early Mars climatic evolution from impact crater degradation
Authors: Mangold N. , Adeli S. , Conway S. , Ansan V. , Langlais B.
Published: February 2012

The degradation of impact craters provides a powerful tool to analyze surface processes in the Martian past. Previous studies concluded that large impact craters (20–200 km in diameter) were strongly degraded by fluvial erosion during early Martian history. Our goal is to study the progression of crater degradation through time with a particular emphasis on the craters with alluvial fans and on the relative chronology of these craters. The geometric properties of 283 craters of >20 km in diameter were analyzed in two highlands of Mars, north of Hellas Planitia, and south of Margaritifer Terra, both known to contain craters with alluvial fans. Three classes were defined from morphology: strongly degraded craters with fluvial landforms and without ejecta (type I), gently degraded craters with fluvial landforms and preserved ejecta (type II), and fresh craters with ejecta and no fluvial landforms (type III). Our main result is that the type II craters that present alluvial fans have characteristics closer to fresh craters (type III) than degraded craters (type I). The distinctive degradation characteristics of these classes allowed us to determine a temporal distribution: Type I craters were formed and degraded between ∼4 Gyr and ∼3.7 Gyr and type II craters with alluvial fans were formed between Early Hesperian and Early Amazonian (∼3.7 to ∼3.3 Gyr). This chronology is corroborated by crosscutting relationships of individual type II craters, which postdate Late Noachian valley networks. The sharp transition at ∼3.7 Gyr suggests a quick change in climatic conditions that could correspond to the cessation of the dynamo.
Tidal triggering of earthquakes prior to the 2011 Tohoku‐Oki earthquake (Mw 9.1)
Authors: Tanaka Sachiko
Published: February 2012

I observe highly significant tidal triggering of earthquakes prior to the 2011 Mw 9.1 Tohoku‐Oki earthquake. Strong statistical correlations between tidally‐induced stresses and earthquake occurrence times are identified in the northern part of the Tohoku‐Oki source region, where the mainshock rupture initiated, in the several to ten years before the Tohoku‐Oki earthquake. The tidal phase distribution of earthquakes in this period exhibits a peak where the shear stress is at its maximum to promote failure. On the other hand, no significant tidal correlation is found after the Tohoku‐Oki mainshock. These observations suggest that tidal triggering occurs over a decade‐long period preceding the Tohoku‐Oki earthquake, and the initial rupture site of this event is already critically stressed in this precursory stage.
Mental Health Illiteracy? Perceiving Depression as a Disorder
Authors: Blease Charlotte
Published: February 2012

World Health Organization statistics reveal that depression is not only one of the leading causes of disability in the world today but it is an illness on the rise. I review research into public attitudes to depression and the effectiveness of recent education campaigns. I contend that while there appears to be evidence that depression is met with serious and persistent stigma, there is a dearth of research in this area. In this article, I forward an explanation for how we might understand the apparent persistence of, and some of the stigmatizing responses to, depression; I term this hypothesis the “Cheater-Detection Model of Depression Stigmatisation” (CDMD). This article proposes that certain behavioral traits associated with depression (specifically: fatigue, cognitive and motor retardation, occupational impairment) may be detected (erroneously) via a specific suite of cognitive mechanisms which were selected for their capacity to gauge cooperation and social exchange among individuals. I argue that the symptoms of depressive behavior which interfere with social and occupational capacities may trigger responses which were selected for in order to avoid exploitation by “cheaters” (that is to say, individuals who are perceived to benefit from social exchange but who are not judged to reciprocate). Evolutionary psychology informs us that perception of cheating behavior tends to elicit affective responses such as anger and avoidance: I argue that some symptoms of depression tend to induce “false-positive” stigmatizing responses. I conclude that until we understand the cognition underlying stigmatization we cannot expect to target it effectively.
The role of deposition conditions on the structure and magnetic properties of SrTi1-xFexO3 films
Authors: Kim Dong Hun , Aimon Nicolas M. , Bi Lei , Dionne Gerald F. , Ross C. A.
Published: February 2012

SrTi1-xFexO3 thin films were grown on Si substrates with a double buffer layer of ceria and yttria-stabilized zirconia at various temperatures, oxygen pressures and Fe contents. Films with in-plane compressive strain and an oxygen deficiency have a strong magnetic anisotropy with an out-of-plane easy axis, whereas films deposited at low temperature and in an oxygen atmosphere have no ferromagnetism at room temperature, which is attributed to the lack of lattice strain.
Amplification of spin waves by the spin Seebeck effect
Authors: Padrón-Hernández E. , Azevedo A. , Rezende S. M.
Published: February 2012

We observe amplification of spin-wave packets propagating along a film of single-crystal yttrium iron garnet (YIG) subject to a transverse temperature gradient. The spin waves are excited and detected with standard techniques used to study volume or surface magnetostatic waves in the 1–2 GHz frequency range. Amplification gains larger than 20 are observed in a YIG film heated by a current of 20 mA in a Pt layer in a simple YIG/Pt bilayer. The amplification is attributed to the action of a spin-transfer thermal torque acting on the magnetization that opposes the relaxation and which is created by spin currents generated through the spin Seebeck effect. The experimental data are interpreted with a spin-wave model.
Fabrication of [001] L1-FePtRh ferro-antiferromagnetic pattern by flat-patterning method
Authors: Hasegawa T. , Tomioka T. , Kondo Y. , Yamane H. , Ishio S.
Published: February 2012

A flat-patterning method that exploits the ferromagnetic (FM) – antiferromagnetic (AF) transition in [001]-oriented L10 FePt1-xRhx films was investigated. FM–AF patterns with dot diameters between 15 and 1000 nm were fabricated by locally diffusing a small percentage of FePt atoms onto the FePt1-xRhx film. The geometric and magnetic properties of the patterns were analyzed in detail. Only the area whose composition crossed the FM–AF threshold underwent a magnetic phase change to the FM phase. FM dots with single-domain structures were observed in the AF matrix in the range of 15–100 nm by magnetic force microscopy.
Mechanisms of Stranski-Krastanov growth
Authors: Baskaran Arvind , Smereka Peter
Published: February 2012

Stranski-Krastanov (SK) growth is reported experimentally as the growth mode that is responsible for the transition to three dimensional islands in heteroepitaxial growth. A kinetic Monte Carlo (KMC) model is proposed that can replicate many of the experimentally observed features of this growth mode. Simulations reveal that this model effectively captures the SK transition and subsequent growth. Annealing simulations demonstrate that the wetting layer formed during SK growth is stable, with entropy playing a key role in its stability. It is shown that this model also captures the apparent critical thickness that tends to occur at higher deposition rates and for alloy films (where intermixing is significant). This work shows that the wetting layer thickness increases with increasing temperature, whereas the apparent critical thickness decreases with increasing temperature. Both of which are in agreement with experiments.
A unit commitment study of the application of energy storage toward the integration of renewable generation
Authors: Harris Chioke , Meyers Jeremy P. , Webber Michael E.
Published: February 2012

To examine the potential benefits of energy storage in the electric grid, a generalized unit commitment model of thermal generating units and energy storage facilities is developed. Three different storage scenarios were tested—two without limits to total storage assignment and one with a constrained maximum storage portfolio. Given a generation fleet based on the City of Austin’s renewable energy deployment plans, results from the unlimited energy storage deployment scenarios studied show that if capital costs are ignored, large quantities of seasonal storage are preferred. This operational approach enables storage of plentiful wind generation during winter months that can then be dispatched during high cost peak periods in the summer. These two scenarios yielded $70 million and $94 million in yearly operational cost savings but would cost hundreds of billions to implement. Conversely, yearly cost reductions of $40 million can be achieved with one compressed air energy storage facility and a small set of electrochemical storage devices totaling 13 GWh of capacity. Similarly sized storage fleets with capital costs, service lifetimes, and financing consistent with these operational cost savings can yield significant operational benefit by avoiding dispatch of expensive peaking generators and improving utilization of renewable generation throughout the year. Further study using a modified unit commitment model can help to clarify optimal storage portfolios, reveal appropriate market participation approaches, and determine the optimal siting of storage within the grid.