bluuebunny/crossref_metadata_2025 huggingface dataset:
Work restrictions experienced by midlife family care-givers of older people: evidence from six European countries
Authors: PRINCIPI ANDREA , LAMURA GIOVANNI , SIROLLA CRISTINA , MESTHENEOS LIZ , BIEŃ BARBARA , BROWN JAYNE , KREVERS BARBRO , MELCHIORRE MARIA GABRIELLA , DÖHNER HANNELI
Published: October 2012

This paper examines differences in work restrictions of midlife family carers of older people in terms of prevalence, gender and explanatory variables, in six European countries: Germany, Greece, Italy, Poland, Sweden and the United Kingdom. A sample of 2,897 carers aged 45–64 was extracted from the EUROFAMCARE (Services for Supporting Family Carers of Older People in Europe: Characteristics, Coverage and Usage) European project database, in order to analyse four possible work restrictions experienced in connection with the activity of care-giving: the reduction of working hours; giving up working; difficulties in career developments and forced occasional work. The results show that work restrictions are experienced differently between countries especially by women: they are reported to a higher degree in the United Kingdom, Germany and Greece, less so in Italy, and seldom in Poland and Sweden. Gender differences within countries are not so marked. Country differences are explained in the light of the different welfare regimes characterising the countries under investigation, in order to elucidate how policy makers may act to improve working carers' conditions through appropriate policies.
Hausdorff dimension of the set of elliptic functions with critical values approaching infinity
Authors: GAŁĄZKA PIOTR
Published: October 2012

Let Λ denote the Weierstrass function with a period lattice Λ. We consider escaping parameters in the family βΛ, i.e. the parameters β for which the orbits of all critical values of βΛ approach infinity under iteration. Unlike the exponential family, the functions considered here are ergodic and admit a non-atomic, σ-finite, ergodic, conservative and invariant measure μ absolutely continuous with respect to the Lebesgue measure. Under additional assumptions on Λ, we estimate the Hausdorff dimension of the set of escaping parameters in the family βΛ from below, and compare it with the Hausdorff dimension of the escaping set in the dynamical space, proving a similarity between the parameter plane and the dynamical space.
Rooted trees, strong cofinality and ample generics
Authors: MALICKI MACIEJ
Published: October 2012

We characterize those countable rooted trees with non-trivial components whose full automorphism group has uncountable strong cofinality, and those whose full automorphism group contains an open subgroup with ample generics.
On the universal sl2 invariant of Brunnian bottom tangles
Authors: SUZUKI SAKIE
Published: October 2012

The universal sl2 invariant is an invariant of bottom tangles from which one can recover the colored Jones polynomial of links. We are interested in the relationship between topological properties of bottom tangles and algebraic properties of the universal sl2 invariant. A bottom tangle T is called Brunnian if every proper subtangle of T is trivial. In this paper, we prove that the universal sl2 invariant of n-component Brunnian bottom tangles takes values in a small subalgebra of the n-fold completed tensor power of the quantized enveloping algebra Uh(sl2). As an application, we give a divisibility property of the colored Jones polynomial of Brunnian links.
Distribution of tubulointerstitial nephritis antigen-like 1 and structural matrix proteins in mouse embryos during preimplantation developmentin vivoandin vitro
Authors: Sakurai Masahiro , Sato Yusuke , Mukai Kuniaki , Suematsu Makoto , Fukui Emiko , Yoshizawa Midori , Tanemura Kentaro , Hoshino Yumi , Matsumoto Hiromichi , Sato Eimei
Published: October 2012

Tubulointerstitial nephritis antigen-like 1 (TINAGL1) is a novel matricellular protein that interacts with structural matrix proteins and promotes cell adhesion and spreading. We have previously reported unique localization of TINAGL1 to the trophectoderm (TE) of mouse blastocysts. TINAGL1 was found to be upregulated in implantation-competent blastocysts after estrogen treatment using progesterone-treated delayed-implantation models. Moreover, colocalization of TINAGL1 and extracellular matrix (ECM) protein laminin 1 was detected in the Reichert membrane on embryonic days 6.5 and 7.5. Although these data suggested a role for TINAGL1 in the embryo development at postimplantation, its relevance to other ECM proteins during preimplantation development is not clear. In this study, we examined the expression of TINAGL1 and its relevance to other ECM proteins fibronectin (FN) and collagen type IV (ColIV) duringin vivodevelopment of preimplantation embryos, particularly at blastocyst stage in detail. Localizations of TINAGL1, FN, and ColIV were similar. In 1-cell to 8-cell embryos, they were expressed in cytoplasm of blastomeres, and in morulae they were localized in the outer cells. FN and ColIV were expressed primarily on outer surface of the cells. In blastocysts, FN and ColIV were distributed in the cytoplasm of TE, but, just prior to implantation, they became localized uniquely to the blastocoelic surface of TE. Inin vitrofertilized (IVF) blastocysts, expression levels of TINAGL1 and FN were lower than inin vivoblastocysts. These results suggest that, during preimplantation development, TINAGL1 may be involved in roles of structural matrix proteins, whose expression in blastocysts may be affected byin vitroculture.
Familial congenital heart disease: data collection and preliminary analysis
Authors: Wang Xike , Wang Jing , Zhao Pengjun , Guo Ying , Wu Lanping , Sun Jing , Sun Kun
Published: October 2012

The aim of this study was to explore genetic mechanisms of congenital heart disease by analysing family data. Families with two or more affected members were studied, and information on family history and risk factors was collected. A total of 25 families with congenital heart disease were identified, and among them the condition was confirmed in 57. The prevalence of congenital heart disease in first-degree relatives was 43.0%, that is 46 out of 107, significantly higher than that in second-degree relatives, that is, 4.4%, 11 out of 252) (χ2= 83.897,P< 0.01). The prevalence difference between twins (90%) and siblings (62.2%) (χ2= 4.983,P< 0.05) was also significant among first-degree relatives. Eleven families were found to have the same phenotype (44%), including ventricular septal defect in six families, atrial septal defect in two families, conotruncal defects in two families, and hypoplastic left heart syndrome in one family. Both twins were diagnosed with congenital heart disease in 8 out of 10 twin families – all eight twins were monozygotic. The cardiac phenotype of the twins was consistent in three families (37.5%). The cardiac phenotype of first- and second-degree relatives was not fully consistent with their probands. There was an increased incidence of threatened abortion in early pregnancy in patients with familial congenital heart disease when compared with sporadic congenital heart disease (χ2= 8.704,P< 0.05). Morbidity in relatives was related to blood relationship, with a closer relationship increasing the risk of congenital heart disease. Genetic factors appear to play an important role in congenital heart disease.
Validierung der türkischen Version des Screenings für Somatoforme Störungen (SOMS) 1Wir danken Frau Z. Subasi für ihre Hilfe in der Begleitung der Patienten in der ersten Einsatzphase des türkischen SOMS.
Authors: Erim Yesim , Beckmann Mingo , Tagay Sefik , Aygün Sanem , Gencoglu Peykan Gökalp , Senf Wolfgang
Published: October 2012

Bei türkischstämmigen Migranten ist die Inanspruchnahme psychotherapeutischer Behandlung häufig mit somatoformen Beschwerden verknüpft. Zur besseren Objektivierung dieser Beschwerden wurde das Screening für Somatoforme Störungen (SOMS), das körperliche Beschwerden nicht organischer Genese erfasst, in die türkische Sprache übersetzt und anhand einer Stichprobe von 114 türkischsprachigen Patienten einer muttersprachlichen psychosomatischen Ambulanz sowie einer Gruppe von 105 psychisch unauffälligen türkischen Migranten validiert. Die türkische Version des SOMS wies eine hohe interne Konsistenz (von α = 0.78 bis α = 0.93), eine hohe konkurrente und divergente Validität (von r = .37 bis r = –.48) anhand von Depressivitätsscores nach dem Beck-Depressions-Inventar und dem Gesamtscore des Kohärenzgefühls nach der Sense of Coherence Scale sowie eine hohe diskriminante Validität auf. Mit der türkischen Version des SOMS wird ein verständliches, reliables und valides Instrument zur Erfassung somatoformer Symptome bei türkischen Migranten vorgelegt.
Radium and radon tracers in aquatic systems
Authors: Moran S. B.
Published: October 2012

Fourth International Ra‐Rn Workshop;Narragansett, Rhode Island, 3–8 June 2012 Radium (Ra) and radon (Rn) are widely recognized as important geochemical tracers in the estimation of dispersion in aquatic environments, submarine groundwater discharge (SGD) to the coastal ocean, water mass residence times, and air‐sea and water‐ sediment exchange. More than 50 scientists, including graduate students and early‐ career scientists from 10 countries, recently participated in a workshop on Ra and Rn in Narragansett, R. I. The workshop was hosted by the University of Rhode Island and sponsored by the U.S. National Science Foundation Chemical Oceanography Program, ORTEC, Eichrom, and Durridge Company. The workshop provided a forum for presentations and open discussions regarding the latest developments and new directions in the application and measurement of isotopes 223Ra, 224Ra, 226Ra, 228Ra, and 222Rn, as well as models used in the application of these tracers to a range of environmental problems.
2011 editors' citations for excellence in refereeing
Authors: Anonymous
Published: October 2012

The reviewers listed below have been cited by editors of AGU journals for excellence in refereeing. The editors' citations recognize this special service to the Union, and these individuals (photographs provided as available) are to be commended for consistently providing constructive and thoughtful reviews.
AGU scientists urge Congress to invest in research and science education
Authors: Rothacker Catherine
Published: October 2012

With the “fiscal cliff” of sequestration drawing closer and threatening to hit basic science research funding with an 8.2% cut, according to an estimate by the Office of Management and Budget, congressional compromise on a budget plan is more urgent than ever. To discuss the value of scientific research and education with their senators and representatives, 55 Earth and space scientists from 17 states came to Washington, D. C., on 11–12 September to participate in the fifth annual Geosciences Congressional Visits Day sponsored by AGU and six other geoscience organizations. Although their specialties varied from space weather to soil science, the scientists engaged members of Congress and their staff in a total of 116 meetings to discuss a common goal: securing continued, steady investment in the basic scientific research that allows scientists to monitor natural hazards, manage water and energy resources, and develop technologies that spur economic growth and job creation. To make the most of these visits on 12 September, participants attended a training session the previous day, during which they learned about the details of the policy‐ making process and current legislative developments and practiced conducting a congressional meeting. Congressional Science Fellows, including past AGU fellow Rebecca French, described their experiences as scientists working on Capitol Hill, and White House policy analyst Bess Evans discussed the president's stance on sequestration and funding scientific research.
Low calcification in corals in the Great Barrier Reef
Authors: Bhattacharya Atreyee
Published: October 2012

Reef‐building coral communities in the Great Barrier Reef—the world's largest coral reef—may now be calcifying at only about half the rate that they did during the 1970s, even though live coral cover may not have changed over the past 40 years, a new study finds. In recent decades, coral reefs around the world, home to large numbers of fish and other marine species, have been threatened by such human activities as pollution, overfishing, global warming, and ocean acidification; the latter affects ambient water chemistry and availability of calcium ions, which are critical for coral communities to calcify, build, and maintain reefs. Comparing data from reef surveys during the 1970s, 1980s, and 1990s with present‐day (2009) measurements of calcification rates in One Tree Island, a coral reef covering 13 square kilometers in the southern part of the Great Barrier Reef, Silverman et al. show that the total calcification rates (the rate of calcification minus the rate of dissolution) in these coral communities have decreased by 44% over the past 40 years; the decrease appears to stem from a threefold reduction in calcification rates during nighttime.
New constraints on the provenance of the ANDRILL AND‐2A succession (western Ross Sea, Antarctica) from apatite triple dating
Authors: Zattin Massimiliano , Andreucci Benedetta , Thomson Stuart N. , Reiners Peter W. , Talarico Franco M.
Published: October 2012

Apatite triple dating (fission track, U‐Pb and U‐Th/He techniques) has been applied to detrital grains from the sedimentary core drilled during the ANDRILL 2A project, which documents the Miocene history of the Victoria Land Basin (western Ross Sea). High‐temperature cooling ages show two main clusters (about 30 and 500 Ma) whereas most of low‐temperature data are late Oligocene‐Early Miocene in age. These latter data are related to the exhumation of the Transantarctic Mountains south of the Discovery Accommodation Zone. Comparison between low‐temperature ages suggests that the Transantarctic Mountains have been in a phase of post‐orogenic decay since at least 30 Ma. The Oligocene U‐Pb data demonstrate the presence of a volcanic event well before the McMurdo volcanic group, whose onset is commonly places at 19 Ma. The location of the volcanic centers is unknown, but they could be below the Ross Ice Shelf south of drilling site. As a whole, these data indicate a major flow of sediments from south to north with only minor contributions from nearby outlet glaciers of the East Antarctic Ice Sheet.
Evaluation of monsoon seasonality and the tropospheric biennial oscillation transitions in the CMIP models
Authors: Li Yue , Jourdain Nicolas C. , Taschetto Andréa S. , Ummenhofer Caroline C. , Ashok Karumuri , Sen Gupta Alexander
Published: October 2012

Characteristics of the Indian and Australian summer monsoon systems, their seasonality and interactions are examined in a variety of observational datasets and in the Coupled Model Intercomparison Project Phase 3 and 5 (CMIP3 and CMIP5) climate models. In particular, it is examined whether preferred monsoon transitions between the two regions and from one year to another, that form parts of the Tropospheric Biennial Oscillation, can lead to improved predictive skill. An overall improvement in simulation of seasonality for both monsoons is seen in CMIP5 over CMIP3, with most CMIP5 models correctly simulating very low rainfall rates outside of the monsoon season. The predictability resulting from each transition is quantified using a Monte Carlo technique. The transition from strong/weak Indian monsoon to strong/weak Australian monsoon shows ∼15% enhanced predictability in the observations, in estimating whether the following monsoon will be stronger/weaker than the climatology. Most models also successfully simulate this transition. However, enhanced predictability for other transitions is less clear.
Enhancement of thermospheric mass density by soft electron precipitation
Authors: Zhang B. , Lotko W. , Brambles O. , Wiltberger M. , Wang W. , Schmitt P. , Lyon J.
Published: October 2012

Enhancements in F‐region electron density and temperature and bottomside Pedersen conductivity caused by soft electron precipitation are shown to enhance the Joule heating per unit mass and the mass density of the thermosphere atF‐region altitudes. The results are derived from the coupled magnetosphere‐ionosphere‐thermosphere model (CMIT) including two types of causally specified soft electron precipitation—direct‐entry cusp precipitation and Alfvén‐wave induced, broadband electron precipitation—the effects of which are self‐consistently included for the first time in a coupled global simulation model. The simulation results provide a causal explanation of CHAMP satellite measurements of statistical enhancements in thermospheric mass density at 400 km altitudes in the cusp and premidnight auroral region.
Type II radio bursts: 2. Application of the new analytic formalism
Authors: Schmidt J. M. , Cairns Iver H.
Published: October 2012

Type II radio bursts drift in frequency as shock waves and coronal mass ejections (CMEs) move through the Sun's corona and the solar wind. This paper applies an extended analytic theoretical model for type II radio bursts to an MHD simulation of the rippled shock front found upstream of the flanks of a CME. The theory treats the acceleration of electrons at the shock, formation of electron beams, growth of Langmuir waves, and conversion of Langmuir energy into radiation. The extended theory is entirely analytic and includes kappa electron velocity distribution functions for the ambient plasma electrons and the shock‐reflected electrons. It also includes the plateauing of the electron beam, which releases energy for the Langmuir waves. This paper presents and discusses our numerical results for synthetic radio source regions and synthetic dynamic spectra, gained by applying our radiation model to an MHD simulation of a shock driven by a CME. The investigation reveals strong emission upstream of the flanks of the shock. A complicated rippled shock geometry develops with embedded “ripples” that stimulate short‐lived “bright spot” radio sources, which lead to complicated substructures in the dynamic spectrum, and more extended sources that usually have a weaker and more diffuse radio emission. The natural development of ripples on the shock provides a natural link between the ripple theory of Knock, Cairns, and colleagues and the bolt‐on model presented here.
Numerical simulation of gravity wave breaking in the lower thermosphere
Authors: Lund Thomas S. , Fritts David C.
Published: October 2012

Numerical simulations are used to study gravity wave (GW) propagation, instability, and breaking in the lower thermosphere. Compressible effects are accounted for via an anelastic formulation of the equations of motion and we employ a realistic description of the background thermodynamic state. An initially low‐amplitude, monochromatic GW with horizontal wavelength 60 km and intrinsic frequencyN/3.7 is introduced at the lower boundary and allowed to propagate to higher altitudes. The GW steepens as it propagates upward and displays instability and breaking over the altitude range ∼120–160 km. The effects of momentum deposition due to viscous attenuation and wave breaking are studied by comparing simulations which either include or exclude induced changes to the mean wind. These two cases also bound the range of expected behavior for horizontally localized GW packets. When induced changes to the mean wind are excluded, instability and turbulence occur over a broad altitude range spanning several vertical wavelengths. In contrast, the region of instability and turbulence is confined to a much more limited altitude range when induced mean wind effects are included. Wave breaking and turbulence in this case are largely confined within a shear layer formed by GW momentum transport. In time, the shear layer evolves into a critical level which consumes nearly all of the incident GW energy.
Large difference of inhibitive effect of nitrogen deposition on soil methane oxidation between plantations with N‐fixing tree species and non‐N‐fixing tree species
Authors: Zhang Wei , Zhu Xiaomin , Liu Lei , Fu Shenglei , Chen Hao , Huang Juan , Lu Xiankai , Liu Zhanfeng , Mo Jiangming
Published: October 2012

The responses of soil methane (CH4) net fluxes to nitrogen (N) addition in a N‐fixing tree species (Acacia auriculiformis(AA)) and a non‐N‐fixing tree species (Eucalyptus citriodora(EU)) plantation were studied in southern China. Treatments were conducted at each plantation with three N levels (0, 50, and 100 kg N ha−1yr−1for control, medium‐N, and high‐N treatment, respectively, abbreviated as C, MN, and HN). From August 2010 to July 2011, CH4flux was measured biweekly using a static chamber and gas chromatography technique. The soils of both sites acted as sink of atmospheric CH4. The CH4uptake rate in control of theAAsite (36.3 ± 3.2μg CH4‐C m−2h−1) was greater than that of theEUplantation (29.9 ± 0.9μg CH4‐C m−2h−1). In theAAplantation, the averaged rates of CH4uptake for the MN (28.6 ± 2.3μg CH4‐C m−2h−1) and HN treatment (23.8 ± 2.8μg CH4‐C m−2h−1) were decreased by 21% and 35%, respectively, compared to the control. However, there was no change of soil CH4uptake between N‐treated plots and the controls in theEUsite. Our results indicated that there might be large difference of inhibitive effect of N deposition on soil CH4oxidation between theAAandEUplantations. The projected increase of N deposition would weaken the capability of N‐fixing tree species plantations for atmospheric CH4sink in tropical and subtropical regions.
TfR1 interacts with the IKK complex and is involved in IKK–NF-κB signalling
Authors: Kenneth Niall S. , Mudie Sharon , Naron Sanne , Rocha Sonia
Published: October 2012

The IKK [inhibitor of NF-κB (nuclear factor κB) kinase] complex has an essential role in the activation of the family of NF-κB transcription factors in response to a variety of stimuli. To identify novel IKK-interacting proteins, we performed an unbiased proteomics screen where we identified TfR1 (transferrin receptor 1). TfR1 is required for transferrin binding and internalization and ultimately for iron homoeostasis. TfR1 depletion does not lead to changes in IKK subunit protein levels; however, it does reduce the formation of the IKK complex, and inhibits TNFα (tumour necrosis factor α)-induced NF-κB-dependent transcription. We find that, in the absence of TfR1, NF-κB does not translocate to the nucleus efficiently, and there is a reduction in the binding to target gene promoters and consequentially less target gene activation. Significantly, depletion of TfR1 results in an increase in apoptosis in response to TNFα treatment, which is rescued by elevating the levels of RelA/NF-κB. Taken together, these results indicate a new function for TfR1 in the control of IKK and NF-κB. Our data indicate that IKK–NF-κB responds to changes in iron within the cell.
Toward a Quantitative Basis for Assessment and Diagnosis of Apraxia of Speech
Authors: Haley Katarina L. , Jacks Adam , de Riesthal Michael , Abou-Khalil Rima , Roth Heidi L.
Published: October 2012

Purpose

We explored the reliability and validity of 2 quantitative approaches to document presence and severity of speech properties associated with apraxia of speech (AOS).

Method

A motor speech evaluation was administered to 39 individuals with aphasia. Audio-recordings of the evaluation were presented to 3 experienced clinicians to determine AOS diagnosis and to rate severity of 11 speech dimensions. Additionally, research assistants coded 11 operationalized metrics of articulation, fluency, and prosody in the same speech samples and in recordings from 20 neurologically healthy participants.

Results

Agreement among the 3 clinicians was limited for both AOS diagnosis and perceptual scaling, but inter-observer reliability for the operationalized metrics was strong. The relationships between most operationalized metrics and mean severity ratings for corresponding perceptual dimensions were moderately strong and statistically significant. Both perceptual scaling and operationalized quantification approaches were sensitive to the presence or absence of AOS.

Conclusions

Perceptual scaling and operationalized metrics are promising quantification techniques that can help establish diagnostic transparency for AOS. However, because satisfactory reliability cannot be assumed for scaling techniques, effective training and calibration procedures should be implemented. Operationalized metrics show strong potential for enhancing diagnostic objectivity and sensitivity.
Ion-selective Marangoni instability—Chemical sensing of specific cation for macroscopic movement
Authors: Miyaoka Tetsuya , Nishimura Jun , Iida Youhei , Maki Syungo , Shioi Akihisa
Published: October 2012

Spontaneous motion and tension oscillation of an oil/water interface responding to specific cation Ca2+ or Fe3+ were observed when the oil phase containing the anionic surfactant bis(2-ethylhexyl) phosphate came in contact with the cation-containing water. Both the dynamics were the results of Marangoni instability. Complex formation between the anionic surfactant and cation caused the instability. The results showing the level of cation extraction and degree of interfacial tension revealed that the surfactant-cation combination forms an oil-soluble complex with reduced surface activity. Brewster angle microscopy indicated that molecules of the complex tend to aggregate at the interface. This aggregation affected the desorption rate of the complex. We were able to generate ion-selective instability by imposing mechanical and electrochemical perturbations to the interface at equilibrium. The results from these efforts suggested that the aggregation is a type of thermodynamic transition and is required for the onset of instability: Desorption probably occurs as an exfoliation of the aggregated complex, which generates the gradient of interfacial tension. For the standard experiment of biphasic contact, two neighboring interfacial flows compress the local interface between them. We considered that this compression provides mechanical work to the local interface, resulting in desorption of the aggregates and occurrence of instability. Both complex formation and aggregation are possible in the presence of the specific cation. The interface detects the cation via the chemical and thermodynamic processes in order to develop the macroscopic movement, a form of biomimetic motion of the oil/water interface.
Electrical conduction in chalcogenide glasses of phase change memory
Authors: Nardone M. , Simon M. , Karpov I. V. , Karpov V. G.
Published: October 2012

Amorphous chalcogenides have been extensively studied over the last half century due to their application in rewritable optical data storage and in non-volatile phase change memory devices. Yet, the nature of the observed non-ohmic conduction in these glasses is still under debate. In this review, we consolidate and expand the current state of knowledge related to dc conduction in these materials. An overview of the pertinent experimental data is followed by a review of the physics of localized states that are peculiar to chalcogenide glasses. We then describe and evaluate twelve relevant transport mechanisms with conductivities that depend exponentially on the electric field. The discussed mechanisms include various forms of Poole-Frenkel ionization, Schottky emission, hopping conduction, field-induced delocalization of tail states, space-charge-limited current, field emission, percolation band conduction, and transport through crystalline inclusions. Most of the candidates provide more or less satisfactory fits of the observed non-linear IV data. Our analysis calls upon additional studies that would enable one to discriminate between the various alternative models.
Chemo-Marangoni convection driven by an interfacial reaction: Pattern formation and kinetics
Authors: Eckert K. , Acker M. , Tadmouri R. , Pimienta V.
Published: October 2012

A combined study devoted to chemo-Marangoni convection and the underlying kinetics is presented for a biphasic system in which surfactants are produced in situ by an interfacial reaction. The pattern formation studied in a Hele-Shaw cell in both microgravity and terrestrial environments initially shows an ensemble of chemo-Marangoni cells along a nearly planar interface. Soon, a crossover occurs to periodic large-scale interfacial deformations which coexist with the Marangoni cells. This crossover can be correlated with the autocatalytic nature of the interfacial reaction identified in the kinetic studies. The drastic increase in the product concentration is associated with an enhanced aggregate-assisted transfer after the critical micellar concentration is approached. In this context, it was possible to conclusively explain the changes in the periodicity of the interfacial deformations depending on the reactant concentration ratio.
Invariant manifolds and the geometry of front propagation in fluid flows
Authors: Mitchell Kevin A. , Mahoney John R.
Published: October 2012

Recent theoretical and experimental work has demonstrated the existence of one-sided, invariant barriers to the propagation of reaction-diffusion fronts in quasi-two-dimensional periodically driven fluid flows. These barriers were called burning invariant manifolds (BIMs). We provide a detailed theoretical analysis of BIMs, providing criteria for their existence, a classification of their stability, a formalization of their barrier property, and mechanisms by which the barriers can be circumvented. This analysis assumes the sharp front limit and negligible feedback of the front on the fluid velocity. A low-dimensional dynamical systems analysis provides the core of our results.
Convection and reaction in a diffusive boundary layer in a porous medium: Nonlinear dynamics
Authors: Andres Jeanne Therese H. , Cardoso Silvana S. S.
Published: October 2012

We study numerically the nonlinear interactions between chemical reaction and convective fingering in a diffusive boundary layer in a porous medium. The reaction enhances stability by consuming a solute that is unstably distributed in a gravitational field. We show that chemical reaction profoundly changes the dynamics of the system, by introducing a steady state, shortening the evolution time, and altering the spatial patterns of velocity and concentration of solute. In the presence of weak reaction, finger growth and merger occur effectively, driving strong convective currents in a thick layer of solute. However, as the reaction becomes stronger, finger growth is inhibited, tip-splitting is enhanced and the layer of solute becomes much thinner. Convection enhances the mass flux of solute consumed by reaction in the boundary layer but has a diminishing effect as reaction strength increases. This nonlinear behavior has striking differences to the density fingering of traveling reaction fronts, for which stronger chemical kinetics result in more effective finger merger owing to an increase in the speed of the front. In a boundary layer, a strong stabilizing effect of reaction can maintain a long-term state of convection in isolated fingers of wavelength comparable to that at onset of instability.
Temperature behavior of the fundamental optical absorption band in quasi-two-dimensional crystalline MnPS3
Authors: Piryatinskaya V. G. , Kachur I. S. , Slavin V. V. , Yeremenko A. V. , Vysochanskii Yu. M.
Published: October 2012

Optical absorption spectra of the layered semiconductor MnPS3 are measured in the temperature range 12-160 K, which covers the magnetic ordering temperature. It is shown that the interband optical absorption coefficient is well described by a model for direct allowed transitions in three-dimensional compounds, while temperature increases lead to an effective reduction in the band gap. A theoretical model is proposed for optical transitions in crystalline MnPS3. A comparison of experimental data with the theory indicates that the chosen model is adequate.
Electrically active magnetic excitations in antiferromagnets (Review Article)
Authors: Krivoruchko V. N.
Published: October 2012

Operating magnetic resonance by an electric field is a highly nontrivial concept, but is the most demanding function in the future of spin-electronics. Recent observations in a variety of multiferroic materials, named ‘collective electrically active magnetic excitations’ and frequently referred to as “electromagnons,” reveal a possibility of implementing such a function. Experimental advances in terahertz spectroscopy of electromagnons in multiferroics, as well as related theoretical models, are reviewed. Earlier theoretical works, where the existence of electric-dipole-active magnetic excitations in antiferro- and ferrimagnets with collinear spin structure has been predicted, are also discussed. Multi-sublattice magnets with electrically active magnetic excitations at room temperature provide a direct opportunity to transform one type of excitation into another in a terahertz time-domain. This is of crucial importance for magnon-based spintronics, since only short-wavelength exchange magnons allow signal processing at nanoscale distances.
Kinetics of magnetization processes in a quasi-one-dimensional Ising superantiferromagnet [{CH3}3NH]CoCl3 · 2H2O
Authors: Chernyi A. S. , Khatsko E. N. , Rykova A. I. , Eremenko A. V.
Published: October 2012

The processes of magnetization reversal in a single crystal of CoTAC are investigated in the temperature range 4.2–0.5 K. The relaxation processes as a function of the magnetic field, temperature, and time are studied. It is shown that the results obtained are described within the model of interacting superparamagnetic formations—nanoclusters. The characteristic constants of interaction, the energy of barriers and the size of domains are determined.
Reduction of superparamagnetic clusters in the [Co/Cu(111)]n nanofilms, induced by the quantum size effect
Authors: Lukienko I. N. , Kharchenko N. F. , Khrustalev V. M. , Savytskiy V. N. , Fedorchenko A. V. , Desnenko V. A. , Stetsenko A. N. , Zorchenko V. V.
Published: October 2012

It is known that the quantum size effects are important for the formation of morphological properties of metal films. The regularities in the behavior of the superparamagnetic magnetoresistive effect in multilayer nanofilms Co/Cu(111) in a magnetic field, found in the work, indicate the influence of the electron size effect on the formation of clusters in these films. The results of measurements of the high-field magnetoresistive effect are reported for multilayer films [Co/Cu(111)]20 with a constant thickness of cobalt layers and the thickness of copper layer varying from film to film. It is found that an effective size of superparamagnetic formations is reduced in the films with thickness of the copper layers corresponding to the maxima of the antiferromagnetic exchange coupling between cobalt layers. It is suggested that the observed “grinding” of superparamagnetic particles is caused by oscillating changes in the electron density in the interface layer Co/Cu, induced by electron quantum size effect in the copper layers.
Raman scattering in non-polymerized and photo-polymerized C60 films at 5 K
Authors: Peschanskii A. V. , Glamazda A. Yu. , Fomin V. I. , Karachevtsev V. A.
Published: October 2012

The Raman spectra of non-polymerized and photo-polymerized fullerene films of various polymerization degrees were studied at 5 K in the 250–1590 cm−1 range. It was found that the Raman spectra of non-polymerized film display splitting of the lines corresponding to Ag and Hg vibrational modes of free C60 molecule which is induced by the crystal field of the low-temperature phase. The Raman spectra of photo-polymerized films at low temperatures exhibit pronounced lines corresponding to Ag(2) vibrations of monomers, dimers and linear chains. Based on the analysis of the spectra of photo-polymerized films of various polymerization degrees (∼45, ∼85, and ∼95%), the spectrum evolution in the region of molecular modes of fullerene was studied vs. polymerization degree. It was found that in the films with high polymerization degree (∼85 and ∼95%), the linear polymer chains dominate while in the film with lower polymerization degree (∼45%) the dimers are dominant. An increase of polymerization degree entails a significant frequency increase (∼2.8 cm−1) of Ag(2) mode of the fullerene monomer induced by changes in its environment upon the transition from non-polymerized to photo-polymerized films. Such a shift was not observed for the lines corresponding to the fullerene photopolymer.
Spin state of iron—the control parameter of iron-containing HTSC: Dependence of ground state energy, phonon energies and atom positions on the spin state of iron ion in FeTe
Authors: Pashkevich Yu. G. , Shevtsova T. N. , Gusev A. A. , Gnezdilov V. P. , Lemmens P.
Published: October 2012

The density functional theory was applied to calculate the electronic structure, ground state energy, phonon frequencies at the center and at the boundary of the Brillouin zone, as well as the distribution of magnetic moment over d-orbitals of iron in the magnetically ordered phase of FeTe as functions of the magnetic moment—spin state of iron. It was shown that the ground state energy minimum is achieved at a certain distribution of the magnetic moment over d-orbitals and at a certain spin state of the iron ion. The impact of the new type of interaction (“the spin state–lattice” interaction) on the phonon subsystem was studied numerically. It was found that the high-frequency part of the phonon spectra undergoes the most significant changes upon changing the spin state. To describe the properties of iron-containing HTSC compounds, an integral parameter (spin state of iron ion) was suggested.
Segmented waves in a reaction-diffusion-convection system
Authors: Rossi Federico , Budroni Marcello A. , Marchettini Nadia , Carballido-Landeira Jorge
Published: October 2012

The interaction of traveling waves, with both Marangoni and buoyancy driven flows, can generate an extraordinary rich array of patterns ranging from stationary structures to chaotic waves. However, the inherent complexity of reaction-diffusion-convection (RDC) systems makes the explanation of the patterning mechanisms very difficult, both numerically and experimentally. In this paper, we describe the appearance of segmented waves in a shallow layer of an excitable Belousov-Zhabotinsky solution. The segmentation process was found to be dependent both on the depth of the solution and on the excitability of the reaction. We caught the essential features of the system through a RDC model, where the chemical waves were coupled both with surface and bulk fluid motions and we found that by varying the excitability of the reaction, and in turn the wavelength of the chemical fronts, it is possible to create a sort of hydrodynamic resonance structures (corridors), which are responsible for the segmentation process.
The Hartree limit of Born's ensemble for the ground state of a bosonic atom or ion
Authors: Kiessling Michael K.-H.
Published: October 2012

The non-relativistic bosonic ground state is studied for quantum N-body systems with Coulomb interactions, modeling atoms or ions made of N “bosonic point electrons” bound to an atomic point nucleus of Z absolute “electron” charges, treated in Born–Oppenheimer approximation (the nuclear mass M = ∞). By adapting an argument of Hogreve, it is shown that the (negative) \documentclass[12pt]{minimal}\begin{document}${\mathscr B}$\end{document}Bosonic ground state energy \documentclass[12pt]{minimal}\begin{document}${\cal E}_{{\infty }}^{{\mathscr B}}(Z,N)$\end{document}E∞B(Z,N) yields the monotone non-decreasing function \documentclass[12pt]{minimal}\begin{document}$N\mapsto {\cal E}_{{\infty }}^{{\mathscr B}}(\lambda N,N)/N^3$\end{document}N↦E∞B(λN,N)/N3 for any λ > 0. The main part of the paper furnishes a proof that whenever λ ⩾ λ* ≈ 1/1.21, then the limit \documentclass[12pt]{minimal}\begin{document}$\varepsilon (\lambda ):=\lim _{N\rightarrow \infty }{\cal E}_{{\infty }}^{{\mathscr B}}(\lambda N,N)/N^3$\end{document}ɛ(λ):=limN→∞E∞B(λN,N)/N3 is governed by Hartree theory, and the rescaled bosonic ground state wave function factors into an infinite product of identical one-body wave functions determined by the Hartree equation. The proof resembles the construction of the thermodynamic mean-field limit of the classical ensembles with thermodynamically unstable interactions, except that here the ensemble is Born's, with |ψ|2 as ensemble probability density function on \documentclass[12pt]{minimal}\begin{document}$\mathbb {R}^{3N}$\end{document}R3N, with the Fisher information functional in the variational principle for Born's ensemble playing the role of the negative Gibbs entropy functional in the free-energy variational principle for the classical petit-canonical configurational ensemble.
The effects of energy transfer on the Er3+ 1.54 μm luminescence in nanostructured Y2O3 thin films with heterogeneously distributed Yb3+ and Er3+ codopants
Authors: Hoang J. , Schwartz Robert N. , Wang Kang L. , Chang J. P.
Published: October 2012

We report the effects of heterogeneous Yb3+ and Er3+ codoping in Y2O3 thin films on the 1535 nm luminescence. Yb3+:Er3+:Y2O3 thin films were deposited using sequential radical enhanced atomic layer deposition. The Yb3+ energy transfer was investigated for indirect and direct excitation of the Yb 2F7/2 state using 488 nm and 976 nm sources, respectively, and the trends were described in terms of Forster and Dexter's resonant energy transfer theory and a macroscopic rate equation formalism. The addition of 11 at. % Yb resulted in an increase in the effective Er3+ photoluminescence (PL) yield at 1535 nm by a factor of 14 and 42 under 488 nm and 976 nm excitations, respectively. As the Er2O3 local thickness was increased to greater than 1.1 Å, PL quenching occurred due to strong local Er3+ ↔ Er3+ excitation migration leading to impurity quenching centers. In contrast, an increase in the local Yb2O3 thickness generally resulted in an increase in the effective Er3+ PL yield, except when the Er2O3 and Yb2O3 layers were separated by more than 2.3 Å or were adjacent, where weak Yb3+ ↔ Er3+ coupling or strong Yb3+ ↔ Yb3+ interlayer migration occurred, respectively. Finally, it is suggested that enhanced luminescence at steady state was observed under 488 nm excitation as a result of Er3+ → Yb3+ energy back transfer coupled with strong Yb3+ ↔ Yb3+ energy migration.
Electron injection in magnesium-doped organic light-emitting diodes
Authors: Kim Kisoo , Hong Kihyon , Lee Illhwan , Kim Sungjun , Lee Jong-Lam
Published: October 2012

We investigated alkali metal doping mechanism by comparative analysis between an Mg-Alq3 co-deposition (Mg:Alq3) and an Mg deposition on Alq3 films (Mg/Alq3). The operating voltage decreased by 0.4 V and the luminance increased by 60 cd/m2 at 11 mA/cm2 for devices constructed from the Mg:Alq3. However, the device characteristics of Mg/Alq3 samples were degraded. Our experimental results using an in-situ photoemission study showed that alkali metal doping in Alq3 did not induce band bending, but reduce electron injection barrier by charge transfer from alkali metals to Alq3 molecules.
Influence of temperature on linear stability in buoyancy-driven fingering of reaction-diffusion fronts
Authors: Levitán D. , D'Onofrio A.
Published: October 2012

A vertical Hele-Shaw cell was used to study the influence of temperature on Rayleigh-Taylor instabilities on reaction-diffusion fronts. The propagation of the chemical front can thus be observed, and experimental results can be obtained via image treatment. A chemical front produced by the coupling between molecular diffusion and the auto-catalysis of the chlorite-tetrathionate reaction, descends through the cell, consuming the reactants below while the product is formed above. Buoyancy-driven instabilities are formed due to the density difference between reactants and products, and the front takes a fingering pattern, whose growth rate has temperature dependence. In this study, the effect of temperature on the linear regime of the instability (that is, when the effects of such instability start to appear) was analyzed. To measure the instability, Fourier transform analysis is performed, in order to obtain the different wave numbers and their power as a function of time. Thus, the growth rate for each wave number and the most unstable wave number is obtained for each of the temperatures under study. Based on repeated experiments, a decrease in the growth rate for the most unstable wave number can be observed with the increase of temperature.
Sequence-dependent thermodynamics of a coarse-grained DNA model
Authors: Šulc Petr , Romano Flavio , Ouldridge Thomas E. , Rovigatti Lorenzo , Doye Jonathan P. K. , Louis Ard A.
Published: October 2012

We introduce a sequence-dependent parametrization for a coarse-grained DNA model [T. E. Ouldridge, A. A. Louis, and J. P. K. Doye, J. Chem. Phys. 134, 085101 (2011)]10.1063/1.3552946 originally designed to reproduce the properties of DNA molecules with average sequences. The new parametrization introduces sequence-dependent stacking and base-pairing interaction strengths chosen to reproduce the melting temperatures of short duplexes. By developing a histogram reweighting technique, we are able to fit our parameters to the melting temperatures of thousands of sequences. To demonstrate the flexibility of the model, we study the effects of sequence on: (a) the heterogeneous stacking transition of single strands, (b) the tendency of a duplex to fray at its melting point, (c) the effects of stacking strength in the loop on the melting temperature of hairpins, (d) the force-extension properties of single strands, and (e) the structure of a kissing-loop complex. Where possible, we compare our results with experimental data and find a good agreement. A simulation code called oxDNA, implementing our model, is available as a free software.
Magnetic properties of Sm0.1Ca0.9MnO3 nanoparticles
Authors: Markovich V. , Fita I. , Wisniewski A. , Puzniak R. , Mogilyansky D. , Kohn A. , Dolgin B. , Iwanowski P. , Gorodetsky G. , Jung G.
Published: October 2012

Magnetic properties of compacted Sm0.1Ca0.9MnO3 nanoparticles with average particle size of 25 and 60 nm have been investigated. It was found that the relative volume of the ferromagnetic phase decreases with decreasing particle size. Magnetization curves measured in field cooled and zero field cooled mode separate near the transition temperature TC and remain different even in magnetic field of 15 kOe. AC-susceptibility is strongly frequency dependent below TC, although the temperature of the maximum depends on frequency only slightly. Magnetization hysteresis loops exhibit horizontal and vertical shifts, relatively small in 60 nm and much larger in 25 nm particles, due to size-dependent exchange bias effect. The exchange bias field and the coercive field depend in a non-monotonic way on cooling magnetic field, while the asymmetry of remanence magnetization and magnetic coercivity increase monotonously with the increase of cooling field. Applied pressure enhances Curie temperature TC of nanoparticles with a pressure coefficient dTC/dP ≈ 0.6 K kbar−1, close to that of the bulk, suggesting that magnetic state of the core is similar to the bulk state. The thermoremanance and isothermoremanance curves provide fingerprints of irreversible magnetization originating from the presence of glassy component. We have ascribed the magnetic behavior of the nanoparticles to a core-shell scenario with phase separated core containing ferromagnetic clusters embedded in an antiferromagnetic matrix and partially disordered antiferromagnetic or paramagnetic shell. The suppression of the ferromagnetic phase in the core with decreasing particle size may account for the enhancement of the exchange bias effect seen in smaller particles.