bluuebunny/crossref_metadata_2025 huggingface dataset:
Photogeneration and recombination of charge carrier pairs and free charge carriers in polymer/fullerene bulk heterojunction films
Authors: Sliaužys Gytis , Arlauskas Kęstutis , Gulbinas Vidmantas
Published: April 2012

Photo‐generation and recombination of free charge carriers in poly‐3 (hexylthiophene) (P3HT) and [6,6]‐phenyl C61 butyric acid methyl ester (PCBM) blend films has been studied at different PCBM concentrations by means of fluorescence spectroscopy and transient photocurrent methods. We show that more than 80% of excitons form charge transfer (CT) states at PCBM concentrations above 4%. Efficiency of the CT state dissociation into free charge carries strongly depends on the PCBM concentration; the dissociation efficiency increases more than 30 times when PCBM concentration increases from 1 to 32%. We attribute the strong concentration dependence to formation of PCBM clusters facilitating electron migration and/or delocalization. Reduced charge carrier recombination coefficient has also been observed at high PCBM concentrations. We suggest that this may be partly caused by the reduced stability of reformed Coulombicaly bound charge pairs.
The effect of temperature on the compressive buckling of boron nitride nanotubes
Authors: Shokuhfar Ali , Ebrahimi‐Nejad Salman , Hosseini‐Sadegh Amin , Zare‐Shahabadi Abolfazl
Published: April 2012

Inspired by the stability at high temperature and the high mechanical strength of boron nitride nanotubes (BNNTs), the effect of temperature on the compressive buckling of BNNTs has been investigated in this paper. Molecular dynamics (MD) simulations of BNNTs subjected to high temperatures (up to 3000 K) were performed and their structures were analyzed by studying their optimized structures at different temperatures through the radial distribution function (RDF). Then, the structural stability and compressive resistance properties of these nanotubes were investigated and the critical buckling loads and critical buckling strains of the nanotubes and their susceptibility to high temperatures were determined. The gradual decrease in the sharpness of the peaks of RDF plots of non‐loaded nanotubes implies that at higher temperatures the structure displays greater deviations from that at room temperature. Results of buckling simulations also indicate a general weakening of the nanotubes and lower critical buckling loads and critical buckling strains at increased temperatures. The decrease in the critical buckling load is more significant for the longer nanotube (L ∼ 6 nm) than the shorter one (L ∼ 3 nm). The critical buckling strain experienced a drop of about 35–50% at temperatures higher than 1500 K. A transitional behavior was observed between T = 1000 and 2000 K.

magnified image

Temperature‐dependent axial buckling behavior of boron nitride nanotubes.
Establishing consistency across all regions in a multi‐regional clinical trial
Authors: Tsou Hsiao‐Hui , James Hung H. M. , Chen Yue‐Ming , Huang Wong‐Shian , Chang Wan‐jung , Hsiao Chin‐Fu
Published: April 2012

In recent years, global collaboration has become a conventional strategy for new drug development. To accelerate the development process and shorten approval time, the design of multi‐regional clinical trials (MRCTs) incorporates subjects from many countries/regions around the world under the same protocol. After showing the overall efficacy of a drug in a global trial, one can also simultaneously evaluate the possibility of applying the overall trial results to all regions and subsequently support drug registration in each region. However, most of the recent approaches developed for the design and evaluation of MRCTs focus on establishing criteria to examine whether the overall results from the MRCT can be applied to a specific region. In this paper, we use the consistency criterion of Method 1 from the Japanese Ministry of Health, Labour and Welfare (MHLW) guidance to assess whether the overall results from the MRCT can be applied to all regions. Sample size determination for the MRCT is also provided to take all the consistency criteria from each individual region into account. Numerical examples are given to illustrate applications of the proposed approach. Copyright © 2012 John Wiley & Sons, Ltd.
State‐Based Prognostics with State Duration Information
Authors: Eker O. F. , Camci F.
Published: April 2012

Failure prediction (i.e. prognostics) is critical for effective maintenance because it greatly impacts the competitiveness of organizations through its direct connection with operating and support costs, system availability, and operational safety. In recent years, research has focused on state‐based prognostics that forecast future progression by first identifying the current state. The duration spent in a state is a factor that influences the expected time to be spent in that state in the future; however, previous works on state‐based prognostics have ignored the effect of duration. Hidden Markov Models are the most famous state‐based prognostics methods in the literature with practicality problems such as computational complexity, requirement of excessive data, and dependency on initialization. This paper presents a new, simple and easy to implement state‐based prognostic method using state duration information. The presented method is applied to two real systems (railway turnout systems and drill bits), and the results are compared with the existing methods presented in the literature. The results show that the presented method outperforms the existing methods. Copyright © 2012 John Wiley & Sons, Ltd.
Thirty‐Femtogram Detection of Iron in Mammalian Cells
Authors: Galimard Aymeric , Safi Malak , Ould‐Moussa Nawel , Montero David , Conjeaud Hélène , Berret Jean‐François
Published: April 2012

Inorganic nanomaterials and particles with enhanced optical, mechanical, or magnetic attributes are currently being developed for a wide range of applications. Safety issues have developed however concerning their potential cyto‐ and genotoxicity. For in vivo and in vitro experimentations, recent developments have heightened the need for simple and facile methods to measure the amount of nanoparticles taken up by cells or tissues. In this work, a rapid and highly sensitive method for quantifying the uptake of iron oxide nanoparticles in mammalian cells is reported. The approach exploits the digestion of incubated cells with concentrated hydrochloric acid reactant and a colorimetric‐based UV–visible absorption technique. The technique allows the detection of iron in cells over 4 decades in masses from 0.03 to 300 picograms per cell. Applied on particles of different surface chemistry and sizes, the protocol demonstrates that the coating is the key parameter in the nanoparticle/cell interactions. The data are corroborated by scanning and transmission electron microscopy, and the results stress the importance of resiliently adsorbed nanoparticles at the plasma membrane.
Effect of Maillard reaction products prepared from glucose–glycine model systems on starch digestibility
Authors: Chung Soo Yeon , Han Sung Hee , Lee Seog Won , Rhee Chul
Published: April 2012

The Maillard reaction is one of the most important phenomena occurring spontaneously during food processing and storage. However, research on the effects of Maillard reaction products (MRPs) on starch hydrolysis remains insufficient. To investigate the effects of MRPs on in vitro starch digestibility, the characteristics of glucose–glycine model system containing MRPs and digestive enzyme activities by MRPs were measured. MRPs were prepared by heating of glucose–glycine mixture solution at 90°C for different times (0, 1, 3, 9, 18, 24, and 48 h). As the Maillard reaction proceeded, browning intensity, and furosine and hydroxymethylfurfural content increased, whereas pH value decreased. The reducing power of MRPs was increased as the Maillard reaction progressed, and MRPs produced in 18 and 24 h showed the highest values (both 1.2). In MRPs heated for 48 h, the reducing sugar content and hydrolysis index were lowest values (88.6 and 87.0%) among the samples. The activity of digestive enzymes significantly decreased by adding of MRPs, as the browning of added MRPs increased. Therefore, MRPs seem to be contributed to decrease in starch digestibility, as shown by an enzymatic digestion result.
On the structural topology of wind turbine blades
Authors: Buckney Neil , Green Steven , Pirrera Alberto , Weaver Paul M.
Published: April 2012

As wind turbines continue to grow in size, it becomes increasingly important to ensure that they are as structurally efficient as possible to ensure that wind energy can be a cost‐effective source of power generation. A way to achieve this is through weight reductions in the blades of the wind turbine. In this study, topology optimization is used to find alternative structural configurations for a 45 m blade from a 3 MW wind turbine. The result of the topology optimization is a layout that varies along the blade length, transitioning from a structure with trailing edge reinforcement to one with offset spar caps. Sizing optimization was then performed on a section with the trailing edge reinforcement and was shown to offer potential weight savings of 13.8% when compared with a more conventional design. These findings indicate that the conventional structural layout of a wind turbine blade is sub‐optimal under the static load conditions that were applied, suggesting an opportunity to reduce blade weight and cost. Copyright © 2012 John Wiley & Sons, Ltd.
What if the Higgs couplings to W and Z bosons are larger than in the Standard Model?
Authors: Falkowski Adam , Rychkov Slava , Urbano Alfredo
Published: April 2012

Abstract

We derive a general sum rule relating the Higgs coupling to W and Z bosons to the total cross section of longitudinal gauge boson scattering in I = 0, 1, 2 isospin channels. The Higgs coupling larger than in the Standard Model implies enhancement of the I = 2 cross section. Such an enhancement could arise if the Higgs sector is extended by an isospin-2 scalar multiplet including a doubly charged, singly charged, and another neutral Higgs.
Hydrogeological Condition and Assessment of Groundwater Resource Using Visual Modflow Modeling, Rajshahi City Aquifer, Bangladesh
Authors: Haque  , Mamunul M. Al , Jahan C. S. , Mazumder Q. H. , Nawaz S. M. S. , Mirdha G. C. , Mamud P. , Adham M. I.
Published: April 2012

The Rajshahi city is the fourth largest metropolitan city in Bangladesh on the bank of the River Padma (Ganges). Here an upper semi-impervious layer overlies aquifer – the source for large-scale groundwater development. The groundwater resource study using Visual MODFLOW modeling shows that recharge occurs mainly due to infiltration of rainfall and urban return flow at low rate, and water level fluctuates seasonally in response to recharge and discharge. Hydraulic connection between river and aquifer which indicates inflow from high river water levels beyond its boundaries. The total groundwater abstraction in 2004 (15000 million liters) is lower than total input to aquifer reveals an ample potentiality for groundwater development with increasing demand. But groundwater shortage (1000 million liter/year) especially in the vicinity of the River Padma in dry season happens due to its increasing use and fall of river water level resulting in reduced inflows and hence decline in groundwater level. The conjunctive use of surface water-groundwater and its economic use will help for sustainable groundwater supply to avoid adverse impact.
Structural Study of Meghalaya Plateau through Aeromagnetic Data
Authors: Sharma Rajendra , Gouda H. C. , Singh R. K. , Nagaraju B. V.
Published: April 2012

The study of aeromagnetic data over parts of Assam-Meghalaya has delineated major discontinuities representing faults/ fractures/ contacts/ shears and magnetic body axes, which helped in understanding the regional and structural setup of the area. The known Barapani and Dapsi Thrusts, Dudhnai Fault and three strong magnetic anomalies with reverse magnetisation have been delineated. The quantitative analysis of aeromagnetic data brought out the depths of magnetic interfaces and the magnetic picture of different layers, which also helped in understanding the regional and structural setup. The contact modeling across few profile sections showed the depths to the top of contacts and the map of magnetic-basement-depth-model revealed the undulations of the basement. Magnetic body axes of several magnetic anomalies and also several magnetic discontinuities representative of faults/ fractures/ contacts/ shears system in the area along with five potential blocks for mineral prospecting are the main outcome of this exercise. The seismotectonic activity associated with the magnetic features has also been studied to understand the structural setup.
Partially labeled data stream classification with the semi-supervised K-associated graph
Authors: Bertini João Roberto , Lopes Alneu de Andrade , Zhao Liang
Published: April 2012

Regular data classification techniques are based mainly on two strong assumptions: (1) the existence of a reasonably large labeled set of data to be used in training; and (2) future input data instances conform to the distribution of the training set, i.e. data distribution is stationary along time. However, in the case of data stream classification, both of the aforementioned assumptions are difficult to satisfy. In this paper, we present a graph-based semi-supervised approach that extends the static classifier based on the K-associated Optimal Graph to perform online semi-supervised classification tasks. In order to learn from labeled and unlabeled patterns, here we adapt the optimal graph construction to simultaneously spread the labels in the training set. The sparse, disconnected nature of the proposed graph structure gives flexibility to cope with non-stationary classification. Experimental comparison between the proposed method and three state-of-the-art ensemble classification methods is provided and promising results have been obtained.
Kinetic and thermodynamic analysis of the conformational folding process of SS‐reduced bovine pancreatic ribonuclease A using a selenoxide reagent with high oxidizing ability
Authors: Arai Kenta , Kumakura Fumio , Iwaoka Michio
Published: April 2012

Redox‐coupled folding pathways of bovine pancreatic ribonuclease A (RNase A) with four intramolecular disulfide (SS) bonds comprise three phases: (I) SS formation to generate partially oxidized intermediate ensembles with no rigid folded structure; (II) SS rearrangement from the three SS intermediate ensemble (3S) to the des intermediates having three native SS linkages; (III) final oxidation of the last native SS linkage to generate native RNase A. We previously demonstrated that DHSox, a water‐soluble selenoxide reagent for rapid and quantitative SS formation, allows clear separation of the three folding phases. In this study, the main conformational folding phase (phase II) has been extensively analyzed at pH 8.0 under a wide range of temperatures (5–45 °C), and thermodynamic and kinetic parameters for the four des intermediates were determined. The free‐energy differences (ΔG) as a function of temperature suggested that the each SS linkage has different thermodynamic and kinetic roles in stability of the native structure. On the other hand, comparison of the rate constants and the activation energies for 3S → des with those reported for the conformational folding of SS‐intact RNase A suggested that unfolded des species (desU) having three native SS linkages but not yet being folded are involved in very small amounts (<1%) in the 3S intermediate ensemble and the desU species would gain the native‐like structures via X‐Pro isomerization like SS‐intact RNase A. It was revealed that DHSox is useful for kinetic and thermodynamic analysis of the conformational folding process on the oxidative folding pathways of SS‐reduced proteins.
Anthropological Reflections on the Breakup of Sudan
Authors: Manger Leif
Published: April 2012

The division of Sudan into two countries on 9 July 2011 following the self-determination referendum of 9 January represents a rare development in Africa. Few examples exist of new state formations in the continent after the end of the colonial period. Answering the call of the IJMES editor to reflect on what this event will mean for our understanding of Sudan might take us in several directions. Let me use this opportunity to comment on two themes that have concerned me lately: the role of the state and the possibility that multiple national identities will evolve in North and South Sudan.
Distribution and conservation status of the Critically EndangeredScrophularia takesimensis, a plant endemic to Ulleung Island, Republic of Korea
Authors: Choi Hyeok Jae , Jang Hyun Do , Isagi Yuji , Un Oh Byoung
Published: April 2012

Scrophularia takesimensisNakai is a Critically Endangered plant species endemic to Ulleung Island, Republic of Korea. We provide updated information on the distribution and conservation status of this species. We located 39 subpopulations and counted a total of 443 individuals, including some reintroduced. Observations of dried and broken branches, with fruits, ofS. takesimensisalong the coast may indicate dispersal by sea. The construction of coastal roads is the main threat to the species. To conserve this species more effectively we recommend that: (1) the two habitats identified as a priority for conservation should be afforded special protection, (2) habitats to the seaward side of coastal roads are more suitable than habitat on the landward side for in situ conservation, and (3) the presently known subpopulations require continuous protection and monitoring.
Lenition, fortition and the status of plosive affrication: the case of spontaneous RP English/t/
Authors: Buizza Emanuela , Plug Leendert
Published: April 2012

This paper reports on a phonetic and phonological study of /t/-affrication in spontaneous British English Received Pronunciation. The study is motivated by the uncertainty surrounding plosive affrication in the literature on lenition and fortition. We suggest that a decision as to the status of a given pattern involving affrication in terms of lenition or fortition should be based on thorough phonetic and phonological analysis. We present a phonetic and phonological account of /t/-affrication, which takes into consideration the temporal and spectral characteristics of the sounds involved, as well as their distribution across phonological environments. Crucially, we compare affricated instances of /t/ with aspirated and fricated ones in the same dataset – the former arguably unmarked in this variety, the latter uncontroversially the result of lenition. We argue that the phonetic and phonological characteristics of /t/-affrication presented in this paper are consistent with an account in terms of fortition rather than lenition.
Canon Law and Theology
Authors: Ombres Robert
Published: April 2012

The relation of religious law to theology is basic to any faith community. In this article, chiefly in terms of Roman Catholicism, but it is hoped of wider application especially within Christianity, the relation of canon law to theology is examined through papal allocutions to the judges and other members of the Church court known as the Roman Rota. There are significant British links to the Rota before and after the Reformation. The 2009 allocution by Benedict XVI is the focus for considering the theological and normative authority of such allocutions. Pius XII has been one of the few canonists to become Pope in modern times, and the co-ordinated set of allocutions from 1945 to 1949 given by him to the Rota is therefore taken as the focus for reflecting on the nature and functions of canon law today. This involves the consideration of both theology and law, including secular law. The ecclesiological character of canon law will emerge as central.
Juridical Ecumenism
Authors: Doe Norman
Published: April 2012

The ecumenical movement seeks to achieve Christian unity through greater visible communion between the separated (or divided) institutional Churches of Christianity worldwide. The practice of ecumenism and ecumenical theology have developed principally at the doctrinal and theological levels. The juridical instruments of Churches have not thus far played a central role in ecumenical discourse – they are occasionally seen as the ‘missing link’ in ecumenism. This article examines for the first time, in a wide comparative compass, the treatment of ecumenism in the juridical instruments of separated Christian traditions and their institutional Churches worldwide. It proposes that these instruments should have a more prominent place in ecumenical practice and theology in so far as they tell us much about the scope of both the commitment of Churches to and their participation in the ecumenical enterprise. Juridical instruments define what ecclesial communion is possible and what is not, either enabling or restricting the development of greater visible communion between separated Churches in the quest for Christian unity. As such, this ‘juridical ecumenism’ offers both a theoretical and a practical framework for the global transformation of ecumenism to complement but not replace the current dominance of the doctrinal and theological focus in contemporary ecumenical method and practice.
Covenant and Communion
Authors: Rees John
Published: April 2012

This article considers some of the controversies that have troubled the Anglican Communion during the past 25 years, and some of the approaches that the Churches and central Instruments of the Communion have used to maintain communion in the face of threatened division. In particular, it looks in detail at the terms of the proposed Anglican Covenant, its provenance and its legal significance. It points out the usefulness of the Covenant as a mechanism for resolving disputes between the Churches of the Communion, but questions the assumption that its adoption as, in effect, a contract between the Churches would of itself turn the Communion into a ‘two-tier’ body, or change in a fundamental way the nature of the relationships between the Churches. Finally, it notes that communion between the Churches of the Anglican Communion, with or without the Covenant, consists (as it always has done) in a wide range of relationships at very many different levels, far beyond the central structures of the Communion as they have developed during the last 150 years.
God, the Bible and Human Rights
Authors: Coulton Nicholas
Published: April 2012

The spat at the 2011 Conservative Party conference between the Home Secretary and the Lord Chancellor showed how contentious human rights legislation remains. Although Theresa May portrayed the claimant as having won the Article 8 right to remain in Britain because of his relationship with his cat, the judge had simply accepted the cat as one piece of evidence that the claimant had a genuine family life with his partner. The Home Secretary's principal point was that the right to respect for private and family life under section 8.1 of the European Convention on Human Rights and Fundamental Freedoms (ECHR) should be read in conjunction with section 8.2, which adds that such rights should not be overridden except where it is

necessary in a democratic society in the interests of national security, public safety, or the economic well-being of the country, for the prevention of disorder or crime, for the protection of health or morals, or for the protection of the rights and freedoms of others.
Parliamentary Report
Authors: Cranmer Frank
Published: April 2012

As predicted, the Charities Act 2011, which consolidates the Recreational Charities Act 1958, the Charities Act 1993 and many of the provisions of the Charities Act 2006, received Royal Assent on 14 December and came into force on 14 March 2012, three months after its enactment.
Uniqueness of the regular waiting-time type solution of the thin film equation
Authors: CHUGUNOVA MARINA , KING JOHN R. , TARANETS ROMAN M.
Published: April 2012

The main result of this paper is the proof of uniqueness of non-negative entropy solutions of the thin film equation ht + (|h|nhxxx)x = 0 for $\frac{7}{4}$ < n < 4. The uniqueness proved under assumptions that the initial data satisfy a finite β-entropy condition for some negative enough exponent β and that the solution is locally monotone at the touchdown point. The new dissipated functional recently constructed by Laugesen (Commun. Pure Appl. Anal., 4(3):613–634, 2005) is used to prove an auxiliary energy equality, and then Grönwall's lemma leads to uniqueness.
Importance of adhesion molecules for children with congenital heart disease
Authors: Yıldırım Ayşe , Karaağaç Aysu T. , Güzelmeriç Fusun , Çine Nihat , Öner Naci C.
Published: April 2012

Background

The aim of our study was to compare the blood levels of adhesion molecules in children with different heart diseases and pulmonary flow rates.

Methods

In this study, we evaluated the levels of soluble intercellular adhesion molecule-1 and soluble vascular cellular adhesion molecule-1 in blood samples of 65 children with different congenital heart diseases. The patients were divided into four groups according to their pulmonary blood flow. The first group had increased pulmonary blood flow with pulmonary hypertension and left-to-right shunt. The second group had increased pulmonary blood flow without pulmonary hypertension and left-to-right shunt. The third group had decreased pulmonary blood flow with cyanotic congenital heart disease and the fourth group had normal pulmonary blood flow with left ventricle outflow tract obstruction and aortic stenosis.

Result

The highest soluble intercellular and vascular cellular adhesion molecule-1 levels with the mean values of 420.2 nanograms per millilitre and 1382.1 nanograms per millilitre, respectively, were measured in the first group and the lowest levels with the mean values of 104.4 and 358.6 nanograms per millilitre, respectively, were measured in the fourth group. The highest pulmonary blood pressure levels were found in the first group.

Conclusion

Endothelial activity is influenced not only by left-to-right shunt with pulmonary hypertension, but also by decreased pulmonary blood flow in cyanotic heart diseases. Adhesion molecules are valuable markers of endothelial activity in congenital heart diseases, and they are influenced by pulmonary blood flow rate.
Right coronary artery fistula to the coronary sinus
Authors: Martínez-Pascual Miryam , Vicente-Vera Tomás , Villegas-García Manuel
Published: April 2012

We report the case of a 26-year-old asymptomatic woman, who presented for consultation after the detection of a cardiac murmur in a medical routine recognition. Doppler echocardiography and the 64-row multidetector computed tomography showed the presence of a significant enlargement of the right coronary artery winding in the contour of the right ventricle and its fistulosa connection to the coronary sinus. Although the coronary fistula in our patient had a considerable size, there was no ventricular dilation, and thus we chose, according to the desire of the patient, not to intervene, and to evaluate her regularly.
“In The Land of the Tarpon”: The Silver King, Sport, and the Development of Southwest Florida, 1885–1915
Authors: Kokomoor Kevin
Published: April 2012

Tarpon fishing offers the opportunity to pursue a narrative of environmental and sport history that focuses on the mutuality between ecology and development. Angling for tarpon illustrates the capacity of an offshore, sporting species to alter the landscape and growth of an entire region. Tarpon fishing reshaped the southwest coast of Florida. In the Charlotte Harbor region, the confluence of human and nonhuman species catalyzed a sporting enterprise that grew dramatically in the late nineteenth and early twentieth centuries. Fishing for tarpon in the Gulf of Mexico was almost exclusively a sporting pursuit, because the unpalatable tarpon had little commercial value. The convergence of the sporting and environmental histories of southwest Florida, the demographics of fishermen and fish, and the development of sporting industries regionally and nationally all provide evidence of the close ecological mutuality that defined tarpon angling during its peak years. On account of features of the fish's annual and life cycle, the region, and the sport, this fishing seemed not to overtax populations of the fish themselves.
Strangers in the Land: A View from Western History
Authors: Benton-Cohen Katherine
Published: April 2012

My task for this retrospective was to discuss John Higham's treatment of region inStrangers in the Land, with particular reference to the American West. My analysis looks especially at race and imperialism. These choices reflect in part the interests and approaches of John Higham, but also the general direction of the field of western history in the twenty-first century.
John Higham's Critique of His Own Work
Authors: Kraut Alan M.
Published: April 2012

In April 2002, the Immigration and Ethnic History Society (IEHS) made its first lifetime achievement award. It was my honor to be president of the IEHS at that time, and I can recall the pleasure and unanimity of board members in designating John Higham the first recipient of that honor. It was a special pleasure for me to notify John and to present the award to him because over the years John had become both a personal friend and a powerful intellectual influence. When I called him at his home in Baltimore, he accepted with delight but as always with the soft-spoken graciousness that was his way. We chatted about the fact that initially he had not defined himself as an immigration scholar, yet in 1967, more than a decade after the publication ofStrangers in the Landhad found himself one of the founding members of what was then called the Immigration History Society and later one of its presidents. As we often did, we also talked about our hometown, New York. John had grown up in Queens, while I had grown up in the South Bronx. On many occasions we discussed how our New York roots had lured us into thinking and writing about immigration and ethnicity.
The low‐temperature magnetic signature of Fe‐rich serpentine in CM2 chondrites: Comparison with terrestrial cronstedtite and evolution with the degree of alteration
Authors: Elmaleh Agnès , Tarantino Serena Chiara , Zema Michele , Devouard Bertrand , Fialin Michel
Published: April 2012

We have studied the low temperature magnetic properties of one CI and five CM2 chondrites, well characterized in the literature, and of cronstedtite, the Fe end‐member of the (Fe,Mg)‐serpentine solid solution. Cronstedtite is highly anisotropic and its relaxation properties below ≈10 K suggest a glassy magnetic behavior. Frustration of the magnetic interactions in octahedral layers would account for the observed magnetic freezing, with a possible role of the random distribution of ferric iron in tetrahedral layers. Based on the comparison between powders and crystals characterized by SCXRD and EMPA, we show that grain size and substitution of octahedral Fe by Mg induce changes in the position of the low‐Tmagnetic susceptibility peak. A low‐Tpeak is also found in each of the CM2 chondrites, but not in the CI chondrite. It is interpreted as the signature of Fe‐serpentines, which are considered by most authors to have mostly formed during asteroïdal aqueous alteration events. The low‐Tmagnetic properties of the less altered meteorites compare well with those of cronstedtite, and the position of the susceptibility peak varies with the published degree of alteration. By comparing magnetic data on reference cronstedtite, magnetic and published mineralogical data on CM2 chondrites, we suggest that the evolution of the low‐Tmagnetic signature of the latter reflects bulk changes in Fe‐serpentines' chemical composition, rather than only mixing between Fe‐rich and Mg‐rich serpentines. This is analogous to previous observations on the changes in Fe incorporation to Mg‐serpentines during progressive serpentinization of abyssal peridotites.
The influence of mineral characteristics on organic matter content, composition, and stability of topsoils under long‐term arable and forest land use
Authors: Kaiser M. , Ellerbrock R. H. , Wulf M. , Dultz S. , Hierath C. , Sommer M.
Published: April 2012

In this study, we analyzed the influence of soil mineral characteristics (e.g., clay concentration and mineralogical composition, iron and aluminum oxide concentration and crystallinity, specific surface area, and exchangeable cation concentration) on (i) organic carbon (OC) content (kg m−2) and (ii) the concentration (g kg−1), composition, and stability of the mineral‐associated organic matter (OM) of arable and forest topsoils. We selected seven soil types with different mineral characteristics for this study. For each soil type, samples were taken from topsoils of a deciduous forest and an adjacent arable site. The arable and forest sites have been used continuously for more than 100 years. Na‐pyrophosphate soluble OM fractions (OM(PY)), representing mineral‐associated OM, were extracted, analyzed for OC and 14C concentrations, and characterized by FTIR spectroscopy. For the forest and arable topsoils, a linear relationship was found between the OC content and exchangeable Ca. For the arable topsoils (pH 6.7–7.5), correlation analyses indicated that the OCPY concentration increased with an increase in oxalate soluble Fe and Al, exchangeable Ca, and Na‐pyrophosphate soluble Mg and Fe concentrations. The stability of OM(PY) determined by the 14C measurements of the near‐neutral arable topsoils was shown to increase with the specific surface area and the concentration of exchangeable Ca. For the acidic forest topsoils (pH <5), the stability of OM(PY) was found to increase as the pH, and the concentration of C=O groups and Na‐pyrophosphate soluble Mg increase.
Use of the Auroral Boundary Index for potential forecasting of ionospheric scintillation
Authors: Griffin James M. , Connor Thomas C. , Snell Hilary E.
Published: April 2012

The Hardy‐Gussenhoven Auroral Dosing Model (HGADM) was developed to compute electron characteristic energy and energy flux values onto the global grid and is often used to generate the inputs for other phenomenological models. Forecasting auroral conditions is limited by rapid changes in the ionosphere due to variable solar conditions. However, through a statistical analysis of Auroral Boundary Index data we have developed a technique which allows us to forecast/predict the appropriate inputs to the HGADM, thereby providing a means of forecasting the characteristic energy and energy flux values. This paper will initially discuss the statistical analysis and the development of the forecast mode for the HGADM. We then discuss the possibility that aurora‐based indices along with other environmental indicators can be correlated to ionospheric disturbances.
Planetary geology and terrestrial analogs in Asia
Authors: Komatsu Goro , Namiki Noriyuki
Published: April 2012

2011 PERC Planetary Geology Field Symposium;Kitakyushu City, Japan, 5–6 November 2011 In spite of the extremely diverse geological settings that exist in Asia, relatively little attention has previously been paid to this region in terms of terrestrial analog studies for planetary application. Asia is emerging as a major center of studies in planetary geology, but no attempt had been made in the past to organize a broadly based meeting that would allow planetary geologists in Asia to meet with ones from more advanced centers, such as the United States and Europe, and that would include the participation of many geologists working primarily on terrestrial research. The Planetary Exploration Research Center (PERC) of the Chiba Institute of Technology hosted the first planetary geology field symposium in Asia to present results from recent planetary geology studies and to exchange ideas regarding terrestrial analogs (http://www.perc.it‐chiba.ac.jp/meetings/pgfs2011/index.html).
Effects of sampling and mineral separation on accuracy of detrital zircon studies
Authors: Sláma Jiří , Košler Jan
Published: April 2012

We investigated some of the sampling and mineral separation biases that affect the accuracy of detrital zircon provenance studies. The study has been carried on a natural catchment in the Scottish Highlands that represents a simple two‐component source system and on samples of synthetic sediment prepared for this study to test the effects of heavy mineral separation on the resulting zircon age spectra. The results suggest that zircon fertility of the source rocks and physical properties of zircon represent the most important factors affecting the distribution of zircon age populations in the stream sediments. The sample preparation and selection of zircons for analysis may result in preferential loss of information from small zircon grains. Together with the preference for larger crystals during handpicking, it can result in several‐fold difference compared to the real age distribution in the sediment sample. These factors appear to be more important for the reproducibility of zircon age spectra than is the number of zircon grains analyzed per sample.
Definition of the binding mode of a new class of phosphoinositide 3-kinase α-selective inhibitors using in vitro mutagenesis of non-conserved amino acids and kinetic analysis
Authors: Zheng Zhaohua , Amran Syazwani I. , Zhu Jiuxiang , Schmidt-Kittler Oleg , Kinzler Kenneth W. , Vogelstein Bert , Shepherd Peter R. , Thompson Philip E. , Jennings Ian G.
Published: April 2012

The binding mechanism of a new class of lipid-competitive, ATP non-competitive, p110α isoform-selective PI3K (phosphoinositide 3-kinase) inhibitors has been elucidated. Using the novel technique of isoform reciprocal mutagenesis of non-conserved amino acids in the p110α and p110β isoforms, we have identified three unique binding mechanisms for the p110α-selective inhibitors PIK-75, A-66S and J-32. Each of the inhibitor's p110α-isoform-selective binding was found to be due to interactions with different amino acids within p110. The PIK-75 interaction bound the non-conserved region 2 amino acid p110α Ser773, A-66S bound the region 1 non-conserved amino acid p110α Gln859, and J-32 binding had an indirect interaction with Lys776 and Ile771. The isoform reciprocal mutagenesis technique is shown to be an important analytical tool for the rational design of isoform-selective inhibitors.
Solid liner implosions on Z for producing multi-megabar, shockless compressions
Authors: Martin M. R. , Lemke R. W. , McBride R. D. , Davis J. P. , Dolan D. H. , Knudson M. D. , Cochrane K. R. , Sinars D. B. , Smith I. C. , Savage M. , Stygar W. A. , Killebrew K. , Flicker D. G. , Herrmann M. C.
Published: April 2012

Current pulse shaping techniques, originally developed for planar dynamic material experiments on the Z-machine [M. K. Matzen et al., Phys. Plasmas 12, 055503 (2005)], are adapted to the design of controlled cylindrical liner implosions. By driving these targets with a current pulse shape that prevents shock formation inside the liner, shock heating is avoided along with the corresponding decrease in electrical conductivity ahead of the magnetic diffusion wave penetrating the liner. This results in an imploding liner with a significant amount of its mass in the solid phase and at multi-megabar pressures. Pressures in the solid region of a shaped pulse driven beryllium liner fielded on the Z-machine are inferred to 5.5 Mbar, while simulations suggest implosion velocities greater than 50kms-1. These solid liner experiments are diagnosed with multi-frame monochromatic x-ray backlighting which is used to infer the material density and pressure. This work has led to a new platform on the Z-machine that can be used to perform off-Hugoniot measurements at higher pressures than are accessible through magnetically driven planar geometries.
Molecular dynamics determination of the surface tension of silver-gold liquid alloys and the Tolman length of nanoalloys
Authors: Calvo F.
Published: April 2012

Using molecular dynamics simulations, an embedded-atom model potential, and the mechanistic route, we have computed the pressure tensor and the surface tension γ of Ag-Au liquid alloys. Although the model generally underestimates γ for pure metals, calculations for a bulk planar slab exhibit nonlinear variations of γ with increasing gold concentration, which agree with experiments and can be accounted for by a perfect solution model. Calculations for various nanoscale droplets containing between 100 and 3200 atoms show a systematic decrease of γ with increasing droplet radius R. The positive Tolman length of the alloy determined from these size variations is estimated to vary slightly with gold concentration. The effects of temperature in the range 1300–1700 K are discussed.
Thermal stability of the geometrically constrained magnetic wall and its effect on a domain-wall spin valve
Authors: Sasaki M. , Matsushita K. , Sato J. , Imamura H.
Published: April 2012

We studied thermal fluctuations in magnetoresistance (MR) signals originating from geometrically confined magnetic walls (GCMWs) of nanometer size. To this end, we developed a novel numerical simulation method which quantitatively evaluates the magnitude of thermal fluctuations in MR signals of magnetic nanostructures. Using the method, we first investigated the case when the twist angle Θ between the magnetization in a fixed layer and that in a free layer is 180°. We found that the thermal fluctuations of the magnetic structure of the 180° GCMW do not induce any crucial fluctuations in the MR signal because there is no significant difference among the MR values of the magnetic structures caused by the thermal fluctuations. We next investigated the dependence on the twist angle Θ of thermal fluctuations in MR signals. Since the GCMW is stabilized by decreasing Θ from 180°, the standard deviation (SD) of the MR signal is reduced with decreasing Θ. On the contrary, the SD/M ratio (M is the mean of the MR signal) monotonically increases with decreasing Θ because the attenuation of the mean value of MR is faster than that of the standard deviation. We also found that the SD/M ratio was not large for any of the temperatures (from 300 to 600 K) and twist angles (from 90° to 180°) we examined. The maximum value of the ratio, which was obtained when T = 600 K and Θ = 90°, was about 13%. This result indicates that thermal fluctuations do not cause significant noise in MR devices that utilize GCMWs of nanometer size.
Competitive role of Mn diffusion with growth in Mn catalyzed nanostructures
Authors: Rehman S. , Hafeez M. , Manzoor U. , Khan M. A. , Bhatti A. S.
Published: April 2012

The use of dopant as a catalyst in the vapor-liquid-solid mode of growth offers a unique way to dope simultaneously the growing nanostructure. This paper reports the use of Mn as a catalyst to grow ZnS nanostructures and simultaneously doping it. It is also shown here that the diffusion rate of Mn in ZnS can be varied to compete with the growth rate of the nanostructures. The diffusion of Mn is found to depend strongly on the Mn layer thickness. The composition of nanowires is determined from X-ray diffraction (XRD) and X-ray photoemission spectroscopy (XPS) measurements. XPS revealed that Mn diffuses only on the surface forming MnS2 compound and its concentration on the surface of nanowires shows a strong dependence on its droplet size. The thermodynamic models are used to examine the interplay of the growth of ZnS nanostructures and Mn diffusion in them. The results show that uniform doping during the growth can be achieved by carefully tuning the growth temperature and the catalyst layer thickness or catalyst droplet size.
A perturbation density functional theory for the competition between inter and intramolecular association
Authors: Marshall Bennett D. , García-Cuéllar Alejandro J. , Chapman Walter G.
Published: April 2012

Using the framework of Wertheim's thermodynamic perturbation theory we develop the first density functional theory which accounts for intramolecular association in chain molecules. To test the theory new Monte Carlo simulations are performed at a fluid solid interface for a 4 segment chain which can both intra and intermolecularly associate. The theory and simulation results are found to be in excellent agreement. It is shown that the inclusion of intramolecular association can have profound effects on interfacial properties such as interfacial tension and the partition coefficient.
Microinstabilities at perpendicular collisionless shocks: A comparison of full particle simulations with different ion to electron mass ratio
Authors: Umeda Takayuki , Kidani Yoshitaka , Matsukiyo Shuichi , Yamazaki Ryo
Published: April 2012

A full particle simulation study is carried out for studying microinstabilities generated at the shock front of perpendicular collisionless shocks. The structure and dynamics of shock waves are determined by Alfvén Mach number and plasma beta, while microinstabilities are controlled by the ratio of the upstream bulk velocity to the electron thermal velocity and the plasma-to-cyclotron frequency. Thus, growth rates of microinstabilities are changed by the ion-to-electron mass ratio, even with the same Mach number and plasma beta. The present two-dimensional simulations show that the electron cyclotron drift instability is dominant for a lower mass ratio, and electrostatic electron cyclotron harmonic waves are excited. For a higher mass ratio, the modified two-stream instability is dominant and oblique electromagnetic whistler waves are excited, which can affect the structure and dynamics of collisionless shocks by modifying shock magnetic fields.
Linear stability analysis on the onset of buoyancy-driven convection in liquid-saturated porous medium
Authors: Chan Kim Min , Kyun Choi Chang
Published: April 2012

The onset of convective motion in an initially quiescent, horizontal isotropic porous layer is analyzed by using linear theory. The fluid-saturated porous layer is assumed to be kept isothermal while a single solute diffuses due to an impulsive change in concentration at an upper boundary. In the semi-infinite domain, using the spectral method, the new linear stability equations are derived and solved analytically by introducing the eigenanalysis and the initial value problem approach. Also, the quasi-steady state approximation (QSSA) is considered. By comparing the stability characteristics obtained with and without QSSA, the validity of the QSSA is discussed. For the deep-pool system, the critical time to onset of convection is found to be τc = 167.547 with the critical wavenumber ac = 0.0695. The present study complements previous theoretical predictions and also will provide the starting points for further studies.
Three-dimensional structure of (110) porous silicon with in-plane optical birefringence
Authors: Shichi Shinsuke , Fujii Minoru , Nishida Tomoki , Yasuda Hidehiro , Imakita Kenji , Hayashi Shinji
Published: April 2012

Electrochemical etching of a (110) oriented Si wafer results in a porous silicon (PSi) layer which exhibits a strong in-plane optical birefringence. We study the refractive index ellipsoid of (110) PSi by angle-resolved optical transmittance measurements and reveal that it is a biaxial crystal. The angle-resolved transmission electron microscope observations demonstrate that pores grow along the directions in between the <100> crystal axes and the etching current flow and these directions depend on the etching current density. The etching current density dependence of the pore direction indicates that the shape of the index ellipsoid can be controlled by the etching condition.
Photoacoustic effect in a sinusoidally modulated structure
Authors: Wu Binbin , Diebold Gerald J.
Published: April 2012

We derive solutions to an inhomogeneous Mathieu equation that describes the photoacoustic effect in a one-dimensional phononic structure whose acoustic properties vary sinusoidally in space. Solutions show splitting of resonances, the space equivalent of subharmonic generation, and spatial confinement. Properties of the photoacoustic effect including the damping of waves inside the band gaps, the dispersion relation, the positions and widths of the gaps, the frequencies of resonances, and the space dependence of the acoustic waves can be found in closed form from known properties of Mathieu functions.