bluuebunny/crossref_metadata_2025 huggingface dataset:
The Diverse Patterns and the Diverse Causes of Migration and Mobility in Science
Authors: Teichler Ulrich , Cavalli Alessandro
Published: April 2015

Five major themes are often addressed in the discourse of mobility in science: the definition and classification of the persons in mind (scholars, academics, researchers, etc); the frequency and the configuration of mobility; the roles mobility and migration play for the individuals; the roles they play for institutions (universities, research institutes, enterprises, etc); and finally the relevance of mobility and migration for the overall international activities within higher education and research in a ‘globalized world’. This article summarizes the concepts and findings presented as regards these themes in all of the articles in this special issue of European Review. The discourse both on concepts and findings suggests that mobility and migration are often viewed in isolation rather than in a wider context of features of internationalization. Moreover, attention often focuses on mobility and migration at the apex of the prestige and quality pyramid, notably in the countries most strongly involved; differences by country, sector and position in the reputational hierarchy would be viewed as more relevant if European policies aimed at a balance between market developments and cohesion across Europe and for keeping inequalities between European countries within limits.
Mobility of Scientists across Europe: The Role Played by European Research Funding
Authors: Zecchina Adriano , Anfossi Alberto
Published: April 2015

The European Research Council has provided substantial research grants across all disciplines during the period 2007–2013. An analysis of the distribution of the ERC (IDEAS) Starting, Consolidator and Advanced grants shows substantial differences by country. On the one hand, the UK excels in the relative number of awards, in its share among the top receiving institutions, in a high proportion of inwards mobile scholars and in the overall financial gain through ERC as compared with the UK’s contribution to the EU budget. In addition, the Netherlands is among the winners in these respects. On the other hand, Italy fares unfavourably according to these measures. In the search for an explanation of the Italian situation, a comparison is undertaken with other European countries of a similar size. The article arrives at the conclusion that low Italian success in efforts to raise such ERC funds is not due to the low average quality of the Italian education and research system, but rather due to low funding, e.g. to a low proportion of the GDP spent on research.
THE PARADOX OF MODERNITY: CURRENT DEBATES AND THEIR IMPLICATIONS FOR THE SEVENTEENTH CENTURY
Authors: REDDY WILLIAM M.
Published: April 2015

Talk of modernity is plagued with paradox. A relativist stance towards modernity—the claim, for example, that modernity is just one cultural configuration among others—seems to contradict itself. The concept of “cultural configuration,” and similar notions (such as “language game,” “discourse,” “community,” or “myth”), are themselves the products of modern intellectual research and debate. If the relativist claim is true, it appears to undermine the validity of those very conditions of modern intellectual debate that make the claim thinkable. But to argue for modernity's superiority over other cultural configurations seems equally problematic. If the criteria of superiority are themselves modern, then the argument appears question-begging. But if the criteria are not modern, then these non-modern criteria (by which the superiority of the modern can be discerned) would appear themselves to be superior to modern criteria.
White House Submits Greenhouse Gas Emission Targets
Authors: Showstack Randy
Published: April 2015

Before the climate summit in Paris this November and December, the United States and some other countries have submitted their targets to cut emissions.
Alzheimer's disease-related amyloid-β induces synaptotoxicity in human iPS cell-derived neurons
Authors: Nieweg K , Andreyeva A , van Stegen B , Tanriöver G , Gottmann K
Published: April 2015

Human induced pluripotent stem cell (iPSC)-derived neurons have been proposed to be a highly valuable cellular model for studying the pathomechanisms of Alzheimer's disease (AD). Studies employing patient-specific human iPSCs as models of familial and sporadic forms of AD described elevated levels of AD-related amyloid-β (Aβ). However, none of the present AD iPSC studies could recapitulate the synaptotoxic actions of Aβ, which are crucial early events in a cascade that eventually leads to vast brain degeneration. Here we established highly reproducible, human iPSC-derived cortical cultures as a cellular model to study the synaptotoxic effects of Aβ. We developed a highly efficient immunopurification procedure yielding immature neurons that express markers of deep layer cortical pyramidal neurons and GABAergic interneurons. Upon long-term cultivation, purified cells differentiated into mature neurons exhibiting the generation of action potentials and excitatory glutamatergic and inhibitory GABAergic synapses. Most interestingly, these iPSC-derived human neurons were strongly susceptible to the synaptotoxic actions of Aβ. Application of Aβ for 8 days led to a reduction in the overall FM4–64 and vGlut1 staining of vesicles in neurites, indicating a loss of vesicle clusters. A selective analysis of presynaptic vesicle clusters on dendrites did not reveal a significant change, thus suggesting that Aβ impaired axonal vesicle clusters. In addition, electrophysiological patch-clamp recordings of AMPA receptor-mediated miniature EPSCs revealed an Aβ-induced reduction in amplitudes, indicating an impairment of postsynaptic AMPA receptors. A loss of postsynaptic AMPA receptor clusters was confirmed by immunocytochemical stainings for GluA1. Incubation with Aβ for 8 days did not result in a significant loss of neurites or cell death. In summary, we describe a highly reproducible cellular AD model based on human iPSC-derived cortical neurons that enables the mechanistic analysis of Aβ-induced synaptic pathomechanisms and the development of novel therapeutic approaches.
Exacerbation of experimental autoimmune encephalomyelitis in ceramide synthase 6 knockout mice is associated with enhanced activation/migration of neutrophils
Authors: Eberle Max , Ebel Philipp , Mayer Christoph A , Barthelmes Julia , Tafferner Nadja , Ferreiros Nerea , Ulshöfer Thomas , Henke Marina , Foerch Christian , de Bazo Anika Männer , Grösch Sabine , Geisslinger Gerd , Willecke Klaus , Schiffmann Susanne
Published: April 2015

Ceramides are mediators of inflammatory processes. In experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS), we observed that CerS6 mRNA expression was upregulated 15‐fold in peripheral blood leukocytes before the onset of EAE symptoms. In peripheral blood leukocytes from MS patients, a 3.9‐fold upregulation was found. Total genetic deletion of CerS6 and the selective deletion of CerS6 in peripheral blood leucocytes exacerbated the progression of clinical symptoms in EAE mice. This was associated with enhanced leukocyte, predominantly neutrophil infiltration and enhanced demyelination in the lumbar spinal cord of EAE mice. Interferon‐gamma/tumor necrosis factor alpha (IFN‐γ/TNF‐α) and granulocyte colony‐stimulating factor (G‐CSF) both drive EAE development and induce expression of the integrin CD11b and the chemokine receptor C‐X‐C motif chemokine receptor 2 (CXCR2), and we found they also induce CerS6 expression. In vivo, the genetic deletion of CerS6 enhanced the activation/migration of neutrophils, as reflected by an enhanced upregulation of CD11b and CXCR2. In vitro, the genetic deletion of CerS6 enhanced the activation status of IFN‐γ/TNF‐α‐stimulated neutrophils, as shown by increased expression of nitric oxide and CD11b and an increased adhesion capacity. In G‐CSF‐stimulated neutrophils, the migration status was enhanced, as reflected by an elevated level of CXCR2 and an increased migration capacity. These data suggest that CerS6/C16‐Cer mediates feedback regulation by inhibiting the formation of CD11b and CXCR2, which are induced either by IFN‐γ/TNF‐α or by G‐CSF, respectively. We conclude that CerS6/C16‐Cer mediates anti‐inflammatory effects during the development of EAE and MS possibly by suppressing the migration and deactivation of neutrophils.
Sphingosine-1-phosphate receptor 3 promotes leukocyte rolling by mobilizing endothelial P-selectin
Authors: Nussbaum Claudia , Bannenberg Sarah , Keul Petra , Gräler Markus H. , Gonçalves-de-Albuquerque Cassiano F. , Korhonen Hanna , von Wnuck Lipinski Karin , Heusch Gerd , de Castro Faria Neto Hugo C. , Rohwedder Ina , Göthert Joachim R. , Prasad Vysakh Pushpa , Haufe Günter , Lange-Sperandio Baerbel , Offermanns Stefan , Sperandio Markus , Levkau Bodo
Published: April 2015

Sphingosine-1-phosphate (S1P) participates in inflammation; however, its role in leukocyte rolling is still unclear. Here we use intravital microscopy in inflamed mouse cremaster muscle venules and human endothelial cells to show that S1P contributes to P-selectin-dependent leukocyte rolling through endothelial S1P receptor 3 (S1P3) and Gαq, PLCβ and Ca2+. Intra-arterial S1P administration increases leukocyte rolling, while S1P3 deficiency or inhibition dramatically reduces it. Mast cells involved in triggering rolling also release S1P that mobilizes P-selectin through S1P3. Histamine and epinephrine require S1P3 for full-scale effect accomplishing it by stimulating sphingosine kinase 1 (Sphk1). In a counter-regulatory manner, S1P1 inhibits cAMP-stimulated Sphk1 and blocks rolling as observed in endothelial-specific S1P1−/− mice. In agreement with a dominant pro-rolling effect of S1P3, FTY720 inhibits rolling in control and S1P1−/− but not in S1P3−/− mice. Our findings identify S1P as a direct and indirect contributor to leukocyte rolling and characterize the receptors mediating its action.
Abundance and genetic damage of barn swallows from Fukushima
Authors: Bonisoli-Alquati A. , Koyama K. , Tedeschi D. J. , Kitamura W. , Sukuzi H. , Ostermiller S. , Arai E. , Møller A. P. , Mousseau T. A.
Published: April 2015

A number of studies have assessed or modeled the distribution of the radionuclides released by the accident at the Fukushima-Daiichi Nuclear Power Plant (FDNPP). Few studies however have investigated its consequences for the local biota. We tested whether exposure of barn swallow (Hirundo rustica) nestlings to low dose ionizing radiation increased genetic damage to their peripheral erythrocytes. We estimated external radiation exposure by using thermoluminescent dosimeters and by measuring radioactivity of the nest material. We then assessed DNA damage by means of the neutral comet assay. In addition, we conducted standard point-count censuses of barn swallows across environmental radiation levels and estimated their abundance and local age ratio. Radioactivity of nest samples was in the range 479–143,349 Bq kg−1, while external exposure varied between 0.15 and 4.9 mGy. Exposure to radioactive contamination did not correlate with higher genetic damage in nestlings. However, at higher levels of radioactive contamination the number of barn swallows declined and the fraction of juveniles decreased, indicating lower survival and lower reproduction and/or fledging rate. Thus, genetic damage to nestlings does not explain the decline of barn swallows in contaminated areas and a proximate mechanism for the demographic effects documented here remains to be clarified.
Chemical aspects of the preservation and safety control of sea foods
Authors: Li Jianrong , Li Tingting , Jiang Yang
Published: April 2015

The interest in biopreservation of food has prompted the quest for new natural antimicrobial compounds from different origins.
Metallophosphoesterases: structural fidelity with functional promiscuity
Authors: Matange Nishad , Podobnik Marjetka , Visweswariah Sandhya S.
Published: April 2015

We present an overview of metallophosphoesterases, highlighting aspects of their biochemistry, structure and function. Despite the high degree of structural similarity these enzymes are versatile in terms of substrate utilization, and in many cases, their precise biological roles remain enigmatic.
Assessment and Treatment of Cognition and Communication Skills in Adults With Acquired Brain Injury via Telepractice: A Systematic Review
Authors: Coleman Jaumeiko J. , Frymark Tobi , Franceschini Nicole M. , Theodoros Deborah G.
Published: April 2015

Purpose

This is a systematic review of assessment and treatment of cognitive and communicative abilities of individuals with acquired brain injury via telepractice versus in person. The a priori clinical questions were informed by previous research that highlights the importance of considering any functional implications of outcomes, determining disorder- and setting-specific concerns, and measuring the potential impact of diagnostic accuracy and treatment efficacy data on interpretation of findings.

Method

A literature search of multiple databases (e.g., PubMed) was conducted using key words and study inclusion criteria associated with the clinical questions.

Results

Ten group studies were accepted that addressed assessment of motor speech, language, and cognitive impairments; assessment of motor speech and language activity limitations/participation restrictions; and treatment of cognitive impairments and activity limitations/participation restrictions. In most cases, equivalence of outcomes was noted across service delivery methods.

Conclusions

Limited findings, lack of diagnostic accuracy and treatment efficacy data, and heterogeneity of assessments and interventions precluded robust evaluation of clinical implications for telepractice equivalence and the broader area of telepractice efficacy. Future research is needed that will build upon current knowledge through replication. In addition, further evaluation at the impairment and activity limitation/participation restriction levels is needed.

Supplemental Material

https://doi.org/10.23641/asha.6170234
Small Groups, Big Gains: Efficacy of a Tier 2 Phonological Awareness Intervention With Preschoolers With Early Literacy Deficits
Authors: Kruse Lydia G. , Spencer Trina D. , Olszewski Arnold , Goldstein Howard
Published: April 2015

Purpose

The purpose of the present study was to evaluate the efficacy of a phonological awareness (PA) intervention, designed for Tier 2 instruction in a Response to Intervention (RTI) model, delivered to small groups of preschoolers.

Method

A multiple-baseline design across participants was used to evaluate the efficacy of the intervention on low-income preschool children's PA skills. A trained interventionist delivered small group sessions 3 to 4 days a week and ensured children received frequent opportunities to respond and contingent feedback. Participants received 28 to 36 lessons that lasted about 10 min each and focused on PA and alphabet knowledge. Initiation of intervention was staggered across 3 triads, and 7 children completed the study.

Results

The intervention produced consistent gains on weekly progress monitoring assessments of the primary outcome measure for first sound identification (First Sound Fluency). Most children also demonstrated gains on other measures of PA and alphabet knowledge.

Conclusions

Results provide support for the application of a small group intervention consistent with an RTI framework and document the potential benefits of the intervention to learners who need early literacy instruction beyond the core curriculum.
Decoding Skills in Children With Language Impairment: Contributions of Phonological Processing and Classroom Experiences
Authors: Tambyraja Sherine R. , Farquharson Kelly , Logan Jessica A. R. , Justice Laura M.
Published: April 2015

Purpose

Children with language impairment (LI) often demonstrate difficulties with word decoding. Research suggests that child-level (i.e., phonological processing) and environmental-level (i.e., classroom quality) factors both contribute to decoding skills in typically developing children. The present study examined the extent to which these same factors influence the decoding skills of children with LI, and the extent to which classroom quality moderates the relationship between phonological processing and decoding.

Method

Kindergarten and first-grade children with LI (
n
= 198) were assessed on measures of phonological processing and decoding twice throughout the academic year. Live classroom observations were conducted to assess classroom quality with respect to emotional support and instructional support.

Results

Hierarchical regression analyses revealed that of the 3 phonological processing variables included, only phonological awareness significantly predicted spring decoding outcomes when controlling for children's age and previous decoding ability. One aspect of classroom quality (emotional support) was also predictive of decoding, but there was no significant interaction between classroom quality and phonological processing.

Conclusions

This study provides further evidence that phonological awareness is an important skill to assess in children with LI and that high-quality classroom environments can be positively associated with children's decoding outcomes.
Persistent Speech Sound Disorder in a 22-Year-Old Male: Communication, Educational, Socio-Emotional, and Vocational Outcomes
Authors: Carrigg Bronwyn , Baker Elise , Parry Louise , Ballard Kirrie J.
Published: April 2015

Persistent Speech Disorder (PSD) is present when a speech impairment extends beyond 8–9 years of age. Persistent Speech Disorder can extend into adolescence and adulthood. While PSD can include individuals with residual speech errors, such as distortions of /r/, /s/, and /z/, clinicians are particularly concerned in cases where PSD affects speech intelligibility. This paper is presented in two parts. Part 1 reviews the limited literature available on speech, language, literacy, educational, vocational, and socio-emotional outcomes in people with PSD of currently unknown origin. Part 2 presents a case study of a 22-year-old man, known as BJ, who has Nonverbal IQ in the normal range and severe PSD, specifically Childhood Apraxia of Speech. Longitudinal data on BJ from 3;3 years to 22 years is presented, alongside BJ's insights into PSD written via e-mail or using his electronic communication device. These two sources of information add to the limited body of information about the course of PSD and the experience of PSD in an individual through to adulthood.
PIFA using series‐resonant feed structure for wide‐band operations
Authors: Zhang Rui , Liu Yang , Kim Hyeonghun , Kim Hyeongdong
Published: April 2015

A newly designed two‐dimensional planar inverted‐F antenna (PIFA) that achieves a substantially enhanced dual‐band impedance bandwidth is presented. It employs a proposed series‐resonant feed structure, which consists of two series resonators. The enhanced dual‐band impedance bandwidth is realised based on the appropriate increase of the impedance levels of the two series resonators. This increase is sufficient to cover wide use in mobile handsets of 698–960 MHz for the low band and 1710–2690 MHz for the high band with a VSWR < 3.
High‐performance suspended stripline wideband bandpass filter with new miniaturisation technology
Authors: Yu Bin , Jia Baofu , Cao Jian , Zhu Zhaojun
Published: April 2015

A simple wideband tubular suspended stripline (SSL) bandpass filter using novel miniaturisation technology is presented. In this design, the equivalent circuit of the proposed filter is considered as the conventional tubular bandpass filter circuit. A new miniaturisation technology called ‘different height of cavity’ is applied to the filter design. A SSL filter is designed and fabricated with the passband from 0.6 to 1 GHz. The insertion loss is better than 0.6 dB in the passband while the return loss is mostly higher than 20 dB. The group delay variation is <0.2 ns. Good agreement between the simulated and measured result is observed, which proves the validity of the technique.
Single op‐amp second‐order loop filter for continuous‐time delta–sigma modulators
Authors: Cho Young‐Kyun , Park Bong Hyuk
Published: April 2015

A second‐order loop filter (LF) that uses a single op‐amp resonator is presented for continuous‐time delta–sigma modulators. The proposed technique improves the power and area efficiency of the LF and enhances the controllability of the transfer function and the resonating condition by providing a new RC network. A second‐order modulator has been designed to confirm the effectiveness of the proposed scheme. Implemented in a 130 nm CMOS, the prototype modulator occupies an active area of 0.098 mm2 and consumes 5.23 mW power from a 1.2 V supply. It achieves a peak SNDR of 60.95 dB over a 15 MHz signal bandwidth with a sampling frequency of 780 MHz.
InP/InGaAs double heterojunction bipolar transistors with BVCEO = 12 V and fmax = 470 GHz
Authors: Kashio N. , Kurishima K. , Ida M. , Matsuzaki H.
Published: April 2015

0.25 μm emitter InP/InGaAs double heterojunction bipolar transistors (DHBTs) are presented that simultaneously exhibit a high collector current density (Jc) of more than 3 mA/μm2 and high breakdown voltage (BVCEO) of 12 V. The DHBTs consist of a 30 nm‐thick InGaAs base, 250 nm‐thick InGaAs/InAlGaAs/InP collector and 150 nm‐thick n‐doped InP field buffer. Since the doping level of the InP field buffer is relatively high, only the InGaAs/InAlGaAs/InP collector is depleted at low VCE. Thus, the DHBTs can provide ft = 173 GHz and fmax = 470 GHz at Jc = 3.5 mA/μm2. On the other hand, at a high VCE, both the InGaAs/InAlGaAs/InP collector and InP field buffer are depleted. Therefore, the effective depletion thickness increases, which results in a BVCEO of 12 V. These results indicate that the use of the InP field buffer provides both high‐speed performance and high BVCEO.
77 GHz waveform generator with multiple frequency shift keying modulation for multi‐target detection automotive radar applications
Authors: Nguyen Quang , Park Myungryeol , Kim Youngsu , Bien Franklin
Published: April 2015

A waveform generator for a 77 GHz automotive radar that uses multiple frequency shift keying (MFSK) modulation is presented. The use of this modulation can improve the detection ability of radar applications in multi‐target situations. The proposed generator consists of a conventional 77 GHz Σ‐Δ fractional‐N synthesiser and MFSK modulation control logic (MMCL). The key innovation is the introduction of the MMCL, which has the ability to track the linear frequency increase while generating the frequency shift keying in each time step. Prior to realising the hardware implementation, a behavioural simulation was evaluated. In addition, a 77 GHz generator module was designed using 130 nm CMOS technology. In a chirp time of 6 ms, there were a total of 128 modulation steps. The bandwidth and frequency step of the chirp were 100 MHz and 300 kHz, respectively.
Comparative study of the electromagnetic performance of switched flux permanent magnet machines
Authors: Zhu Zi Qiang , Al‐Ani Mahir , Lee Beomseok , Liu Xu
Published: April 2015

Switched flux permanent magnet (SFPM) machines have significant potential for many industrial applications because of their doubly salient structure, similar to switched reluctance machines. In recent years, several novel SFPM machine topologies, such as multi‐tooth, E‐core and C‐core, have been developed to reduce the usage of permanent magnet materials without sacrificing the torque capability. A comparative study of the electromagnetic performance of these topologies, together with conventional SFPM machines having different stator/rotor pole combinations, that is, 12/10, 12/13 and 12/14, is presented. In addition to open circuit and electromagnetic torque performance, their torque–speed characteristics are investigated and compared. It is found that for conventional SFPM machines, the higher the rotor pole number, the better the flux‐weakening capability, and higher maximum speed can be achieved. In contrast, owing to high d‐axis inductance in the multi‐tooth, E‐core and C‐core machines, infinite maximum speed can be obtained. Moreover, among all these machines, the multi‐tooth machine has the highest flux‐weakening factor, while the E‐core machine exhibits the largest power capability. In addition to two‐dimensional (2D) finite‐element analysis (FEA), 3D‐FEA is also performed accounting for the end effect. Finally, the torque–speed characteristics of prototype SFPM machines are measured to verify the FEA.
Anisotropic g factors of the tetragonal Cu2+ monomer in Tl-2223 superconductor
Authors: Zhang Zhi-Hong , Wu Shao-Yi , Kuang Min-Quan , Ding Chang-Chun
Published: April 2015

The gyromagnetic factors of the Cu2+ monomer in Tl-2223 superconductor are quantitatively investigated from the perturbation formulas of these factors for a 3d9 ion in a tetragonally elongated octahedron. The local tetragonal distortion of the system is attributable to the axial elongation along c axis, corresponding to the five-fold coordinated Cu2+(2) site with almost 30% longer Cu–O bond length for the apical oxygen as compared to the four planar ones. The significant anisotropic behaviors of the EPR spectra perpendicular to and parallel with the ab (CuO2) layers are analyzed on the basis of the local tetragonal elongation.
Isochoric thermal conductivity of the “plastic” phase of cyclic hydrocarbons. Thiophene
Authors: Konstantinov V. A. , Sagan V. V. , Revyakin V. P. , Karachevtseva A. V.
Published: April 2015

Isochoric thermal conductivity of solid thiophene is measured in “plastic” phase I, on three samples with different molar volumes at temperatures ranging from 170 K to the melting point. The thermal conductivity increased with temperature for all samples. We conducted a comparison with the isochoric thermal conductivity of other cyclic hydrocarbons in “plastic” phases. It is shown that the observed effect correlates to the changes in the magnitude of the NMR second moment in the “plastic” phases, and, respectively, with the degree of disinhibition in the rotational motion of molecules.
Luminescence of Co1−xZnxO solid solutions during interband excitation
Authors: Gruzdev N. B. , Sokolov V. I. , Pustovarov V. A. , Churmanov V. N.
Published: April 2015

A discussion of the photoluminescence (PL) and photoluminescence excitation (PLE) spectra of CoO, and the solid solution Co0.7Zn0.3O. At low temperatures, the spectra were detected using synchrotron radiation as a source of excitation. The PL and PLE spectra of CoO are more intense than the Co0.7Zn0.3O spectra. It is shown that in the 7.5–10.5 eV energy range, the PLE spectrum of Co0.7Zn0.3O is more intense than the spectrum in the 3.7–6.5 eV region. This could be caused by sufficiently intense optical p-s transitions from the valence zone to the conduction zone, formed by the 4s states of zinc.
Creep in solid 4He at temperatures below 1 K
Authors: Zhuchkov V. A. , Lisunov A. A. , Maidanov V. A. , Neoneta A. S. , Rubanskyi V. Yu. , Rubets S. P. , Rudavskii E. Ya. , Smirnov S. N.
Published: April 2015

Creep in solid 4He at temperatures of ∼100–1000 mK is studied experimentally by detecting the flow of helium through a frozen porous membrane under a constant external force. Creep curves are measured for different temperatures and mechanical stresses. This method has made it possible to detect low creep rates in helium down to the lowest temperatures in these experiments. It is found that throughout this temperature range, creep is thermally activated and the activation energy decreases with falling temperature and increasing mechanical stress. An analysis shows that for temperatures above ≈500 mK, Nabarro-Herring diffusive creep takes place in solid helium with mass transfer by self diffusion of atoms and a counterflow of vacancies. The experimental data have been used to obtain the self-diffusion coefficient as a function of temperature for different stresses. At temperatures below ≈500 mK creep takes place at a very low flow rate (∼10−13 cm/s) and a very low activation energy (∼0.5–0.7 K), while the creep mechanism remains unclear.
Morin transition temperature in (0001)-oriented α-Fe2O3 thin film and effect of Ir doping
Authors: Shimomura Naoki , Pati Satya Prakash , Sato Yuji , Nozaki Tomohiro , Shibata Tatsuo , Mibu Ko , Sahashi Masashi
Published: April 2015

The structural properties and Morin transition in c-plane-oriented α-Fe2O3 and Ir-doped α-Fe2O3 thin films have been investigated. The enhancement of the Morin transition temperature (TM) in α-Fe2O3 film by Ir doping has been demonstrated. The TM in the c-plane-oriented α-Fe2O3 thin film was determined from the temperature-dependent in-plane magnetization and change of coercivity (Hc); this TM value was found close to that of bulk α-Fe2O3. The spin directions of non-doped and Ir-doped α-Fe2O3 at room temperature were also estimated from conversion electron Mössbauer spectroscopy measurements. We confirmed that Ir doping dramatically enhances the TM of α-Fe2O3 thin film.
Transitions between strongly correlated and random steady-states for catalytic CO-oxidation on surfaces at high-pressure
Authors: Liu Da-Jiang , Evans James W.
Published: April 2015

We explore simple lattice-gas reaction models for CO-oxidation on 1D and 2D periodic arrays of surface adsorption sites with CO adsorption and desorption, dissociative O2 adsorption and recombinative desorption (at low rate), and CO + O reaction to form CO2. Adspecies interactions are neglected, and adspecies diffusion is effectively absent. The models are motivated by studies of CO-oxidation on RuO2(110) at high-pressures. Despite the lack of adspecies interactions, negligible adspecies diffusion results in kinetically induced spatial correlations. A transition occurs from a random primarily CO-populated steady-state at high CO-partial pressure, pCO, to a strongly correlated near-O-covered steady-state for low pCO as noted by Matera et al. [J. Chem. Phys. 134, 064713 (2011)]. In addition, we identify a second transition to a random near-O-covered steady-state at very low pCO. Furthermore, we identify and analyze the slow “diffusive dynamics” for very low pCO and provide a detailed characterization of the crossover to the strongly correlated O-covered steady-state as well as of the spatial correlations in that state.
Dislocations and crowdions in two-dimensional crystals. II. Elastic fields and intrinsic energies in a 2D hexagonal lattice
Authors: Natsik V. D. , Smirnov S. N.
Published: April 2015

The fields of elastic deformation and stress around the centers of dislocations and crowdions in 2D crystals with isotropic elastic properties are described in the continuum approximation. The elastic energy of both types of defects was calculated and its dependence on crystal size was discussed. Considered also was the quantitative uncertainty associated with the inapplicability of the continual description of deformation at atomic distances from the centers of the defects. The results obtained by using the continuum theory were further improved by comparing with the results of numerical analysis using the methods of molecular dynamics of atomic structure of dislocations and crowdions in a hexagonal 2D crystal. The present work continues the study that was commenced in the previous paper (Fiz. Nizk. Temp. 40, 1366 (2014)).
Backward-propagating MeV electrons from 1018 W/cm2 laser interactions with water
Authors: Morrison J. T. , Chowdhury E. A. , Frische K. D. , Feister S. , Ovchinnikov V. M. , Nees J. A. , Orban C. , Freeman R. R. , Roquemore W. M.
Published: April 2015

We present an experimental study of the generation of ∼MeV electrons opposite to the direction of laser propagation following the relativistic interaction at normal incidence of a ∼3 mJ, 1018 W/cm2 short pulse laser with a flowing 30 μm diameter water column target. Faraday cup measurements record hundreds of pC charge accelerated to energies exceeding 120 keV, and energy-resolved measurements of secondary x-ray emissions reveal an x-ray spectrum peaking above 800 keV, which is significantly higher energy than previous studies with similar experimental conditions and more than five times the ∼110 keV ponderomotive energy scale for the laser. We show that the energetic x-rays generated in the experiment result from backward-going, high-energy electrons interacting with the focusing optic, and vacuum chamber walls with only a small component of x-ray emission emerging from the target itself. We also demonstrate that the high energy radiation can be suppressed through the attenuation of the nanosecond-scale pre-pulse. These results are supported by 2D particle-in-cell simulations of the laser-plasma interaction, which exhibit beam-like backward-propagating MeV electrons.
Tailoring local density of optical states to control emission intensity and anisotropy of quantum dots in hybrid photonic-plasmonic templates
Authors: Indukuri Chaitanya , Mukherjee Arnab , Basu J. K.
Published: April 2015

We report results of controlled tuning of the local density of states (LDOS) in versatile, flexible, and hierarchical self assembled plasmonic templates. Using 5 nm diameter gold (Au) spherical nanoantenna within a polymer template randomly dispersed with quantum dots, we show how the photoluminescence intensity and lifetime anisotropy of these dots can be significantly enhanced through LDOS tuning. Finite difference time domain simulations corroborate the experimental observations and extend the regime of enhancement to a wider range of geometric and spectral parameters bringing out the versatility of these functional plasmonic templates. It is also demonstrated how the templates act as plasmonic resonators for effectively engineer giant enhancement of the scattering efficiency of these nano antenna embedded in the templates. Our work provides an alternative method to achieve spontaneous emission intensity and anisotropy enhancement with true nanoscale plasmon resonators.
Volume-preserving algorithm for secular relativistic dynamics of charged particles
Authors: Zhang Ruili , Liu Jian , Qin Hong , Wang Yulei , He Yang , Sun Yajuan
Published: April 2015

Secular dynamics of relativistic charged particles has theoretical significance and a wide range of applications. However, conventional algorithms are not applicable to this problem due to the coherent accumulation of numerical errors. To overcome this difficulty, we develop a volume-preserving algorithm (VPA) with long-term accuracy and conservativeness via a systematic splitting method. Applied to the simulation of runaway electrons with a time-span over 10 magnitudes, the VPA generates accurate results and enables the discovery of new physics for secular runaway dynamics.
Hard X-ray nanofocusing using adaptive focusing optics based on piezoelectric deformable mirrors
Authors: Goto Takumi , Nakamori Hiroki , Kimura Takashi , Sano Yasuhisa , Kohmura Yoshiki , Tamasaku Kenji , Yabashi Makina , Ishikawa Tetsuya , Yamauchi Kazuto , Matsuyama Satoshi
Published: April 2015

An adaptive Kirkpatrick–Baez mirror focusing optics based on piezoelectric deformable mirrors was constructed at SPring-8 and its focusing performance characteristics were demonstrated. By adjusting the voltages applied to the deformable mirrors, the shape errors (compared to a target elliptical shape) were finely corrected on the basis of the mirror shape determined using the pencil-beam method, which is a type of at-wavelength figure metrology in the X-ray region. The mirror shapes were controlled with a peak-to-valley height accuracy of 2.5 nm. A focused beam with an intensity profile having a full width at half maximum of 110 × 65 nm (V × H) was achieved at an X-ray energy of 10 keV.
Electrically tunable terahertz quantum cascade lasers based on a two-sections interdigitated distributed feedback cavity
Authors: Turčinková Dana , Amanti Maria Ines , Scalari Giacomo , Beck Mattias , Faist Jérôme
Published: April 2015

The continuous electrical tuning of a single-mode terahertz quantum cascade laser operating at a frequency of 3 THz is demonstrated. The devices are based on a two-section interdigitated third-order distributed feedback cavity. The lasers can be tuned of about 4 GHz at a constant optical output power of 0.7 mW with a good far-field pattern.
Optical modeling and electrical properties of cadmium oxide nanofilms: Developing a meta–heuristic calculation process model
Authors: Abdolahzadeh Ziabari Ali , Refahi Sheikhani A. H. , Nezafat Reza Vatani , Haghighidoust Kasra Monsef
Published: April 2015

Cadmium oxide thin films were deposited onto glass substrates by sol–gel dip-coating method and annealed in air. The normal incidence transmittance of the films was measured by a spectrophotometer. D.C electrical parameters such as carrier concentration and mobility were analyzed by Hall Effect measurements. A combination of Forouhi–Bloomer & standard Drude model was used to simulate the optical constants and thicknesses of the films from transmittance data. The transmittance spectra of the films in the visible domain of wavelengths were successfully fitted by using the result of a hybrid particle swarm optimization method and genetic algorithm. The simulated transmittance is in good accordance with the measured spectrum in the whole measurement wavelength range. The electrical parameters obtained from the optical simulation are well consistent with those measured electrically by Hall Effect measurements.
Propagation of pore pressure diffusion waves in saturated porous media
Authors: Yang Duoxing , Li Qi , Zhang Lianzhong
Published: April 2015

A microscopic 1D analytical model was developed for describing pore pressure diffusion wave propagation in porous media. The pressure diffusion waves, being heavily damped, have relatively slow velocities and short wavelength, and do not exhibit square-law behavior. Investigation on permeability effect on attenuation dispersion and penetration depth indicates that the transition zone in attenuation and penetration depth peak shifts toward low frequency when permeability decreases. Controversially, the transition zone in phase velocity peak shifts toward high frequency when permeability decreases. The high frequency-dependent attenuation of low-frequency waves was well predicted by the pressure diffusion mechanism. At a mass interface, pressure diffusion waves obey an accumulation–depletion law, rather than the reflection–refraction law. Pressure diffusion waves are accelerated and amplified by a space-dependent diffusivity field.
Dependence of Curie temperature on Pt layer thickness in Co/Pt system
Authors: Koyama T. , Obinata A. , Hibino Y. , Hirohata A. , Kuerbanjiang B. , Lazarov V. K. , Chiba D.
Published: April 2015

The Pt thickness dependence of the Curie temperature of perpendicularly magnetized ultra-thin (Pt/)Co/Pt films has been investigated by magnetization measurements. The Curie temperature and the saturation magnetic moment increase with the Co layer thickness and even with the Pt layer thickness. The Curie temperature is found to have linear dependence on the total magnetic moment of the system and the coefficients of the linear fits are almost identical, regardless of whether the thicknesses of the ferromagnetic Co layer or the Pt layer are varied. The Curie temperature also increases with the magnetic anisotropy, but no systematic dependence is observed. These results suggest that the magnetic moment induced in the Pt layer by the ferromagnetic proximity effect plays a significant role in determining the Curie temperatures of such two-dimensional ferromagnetic systems.
Charged two-exciton emission from a single semiconductor nanocrystal
Authors: Hu Fengrui , Zhang Qiang , Zhang Chunfeng , Wang Xiaoyong , Xiao Min
Published: April 2015

Here, we study the photoluminescence (PL) time trajectories of single CdSe/ZnS nanocrystals (NCs) as a function of the laser excitation power. At the low laser power, the PL intensity of a single NC switches between the “on” and “off” levels arising from the neutral and positively charged single excitons, respectively. With the increasing laser power, an intermediate “grey” level is formed due to the optical emission from a charged multiexciton state composed of two excitons and an extra electron. Both the inter-photon correlation and the PL decay measurements demonstrate that lifetime-indistinguishable photon pairs are emitted from this negatively charged two-exciton state.
Mixed conduction and grain boundary effect in lithium niobate under high pressure
Authors: Wang Qinglin , Liu Cailong , Gao Yang , Ma Yanzhang , Han Yonghao , Gao Chunxiao
Published: April 2015

The charge transport behavior of lithium niobate has been investigated by in situ impedance measurement up to 40.6 GPa. The Li+ ionic conduction plays a dominant role in the transport process. The relaxation process is described by the Maxwell-Wagner relaxation arising at the interfaces between grains and grain boundaries. The grain boundary microstructure rearranges after the phase transition, which improves the bulk dielectric performance. The theoretical calculations show that the decrease of bulk permittivity with increasing pressure in the Pnma phase is caused by the pressure-induced enhancement of electron localization around O atoms, which limits the polarization of Nb-O electric dipoles.
Rapid thermal annealed Molybdenum back contact for Cu2ZnSnS4 thin film solar cells
Authors: Liu Xiaolei , Cui Hongtao , Kong Charlie , Hao Xiaojing , Huang Yidan , Liu Fangyang , Song Ning , Conibeer Gavin , Green Martin
Published: April 2015

In this work, an industrially viable manufacturing process—rapid thermal annealing (RTA) of Molybdenum back contact is proposed and investigated to improve the performance of sputtered Cu2ZnSnS4 (CZTS) solar cells. The RTA process was found to facilitate Na diffusion from soda lime glass to Mo as well as CZTS and improve the crystallinity of the Mo film. Consequently, the surface morphology of the subsequently deposited CZTS absorbers is improved, which results in significant enhancement of open circuit voltage, short-circuit current density, fill factor, and conversion efficiency.
Bird diversity increases after patchy prescribed fire: implications from a before–after control–impact study
Authors: Sitters Holly , Di Stefano Julian , Christie Fiona J. , Sunnucks Paul , York Alan
Published: April 2015

Increasingly, patchy prescribed fire of low severity is used by land managers to mitigate wildfire risk, but there are relatively few experimental studies on the effects of low-severity fire on fauna. We used a before–after control–impact experiment to examine avian responses to prescribed fire at two scales in topographically variable, tall-open eucalypt forest in south-east Australia. We surveyed birds at control and impact areas twice before and twice after fire, and applied mixed models to investigate responses of avian turnover, richness and the occurrence of selected species. Approximately half of the impact area was burnt and topographic variation generated a finger-like configuration of burnt patches on ridges and unburnt patches in gullies. Our findings at the smaller scale (0.8 ha) indicated that the fire resulted in increased bird diversity because a patchwork of burnt and unburnt areas provided a mosaic of distinct successional states in which different species occurred. Additionally, we found that the effect of fire on species richness and occurrence was a function of the presence of unburnt topographic refuges. In contrast, we found no compelling evidence to suggest that birds responded to the fire at the larger scale (400 ha). We conclude that application of low-severity fire in a patchy manner enhanced avian diversity and facilitated the persistence of the birds detected in pre-fire surveys. Although the levels of patchiness required to sustain diverse taxa warrant further study, our findings highlight the importance of formally incorporating patchiness into prescribed burning for the ecologically sensitive management of contemporary landscapes.
Applicability and Interpretation of Fish Indices of Biotic Integrity (IBI) for Bioassessment in the Upper Midwest
Authors: Ogren Stephanie A. , Huckins Casey J
Published: April 2015

Multiple fish-based indices of biotic integrity (IBIs) and biological condition gradient models have been developed and validated to assess ecological integrity in the Laurentian Great Lakes region. We evaluated the applicability and effectiveness of using fish community indices for assessing site integrity in central Great Lakes streams, which have diverse temperature regimes and can be classified as warmwater, coolwater, or coldwater. Sites with different thermal regimes require different assessment tools to ensure comparability. Streams in the Big Manistee River watershed, Michigan, are near thermal thresholds for classification as coolwater or coldwater. We evaluated two coolwater and three coldwater indices developed for Upper Midwest streams. Output from coolwater indices were not correlated with coldwater index outputs and did not discriminate among the stream systems we evaluated. In monitoring temporal patterns over time (2002–2010), we found that coldwater indices showed similar patterns and agreed in relative scoring of sites from high to low. The three coldwater indices also similarly discriminated among stream systems; however, when the coldwater indices were used for specific site assessments, they produced differential results. Depending on which index was applied, a single site could be classified into three different levels of quality. This highlights the importance of index selection for management actions. An understanding of the factors that drive the indices and an understanding of reference conditions are imperative for effective use of fish-based IBIs in the Upper Midwest.

Received July 15, 2014; accepted December 12, 2014
Harm Reduction Agencies as a Potential Site for Buprenorphine Treatment
Authors: Fox Aaron D. , Chamberlain Adam , Frost Taeko , Cunningham Chinazo O.
Published: April 2015

Background

Harm reduction agencies complement addiction treatment by providing diverse services that improve the health of people who use drugs. Buprenorphine maintenance treatment (BMT) is an effective opioid addiction treatment that may be provided from flexible settings, potentially including harm reduction agencies. This study investigated attitudes toward different potential sites for BMT (harm reduction agencies, general medical clinics, and drug treatment programs) among harm reduction clients.

Methods

Using computer-based interviews, participants indicated preferred potential site for BMT (harm reduction agency, drug treatment program, or general medical clinic), interest in BMT by potential site, motivation for treatment, and barriers to BMT. Multivariable logistic regression was used to determine factors associated with harm reduction agency preference.

Results

Of 102 opioid users, the most preferred potential site for BMT was a harm reduction agency (51%), whereas fewer preferred general medical clinics (13%), drug treatment programs (12%), or were not interested in BMT (25%). In multivariable analysis, experiencing ≥1 barrier to BMT was strongly associated with preferring harm reduction agencies (adjusted odds ratio [aOR] = 3.39, 95% confidence interval [CI]: 1.00–11.43).

Conclusions

The potential to initiate BMT at harm reduction agencies is highly favorable among harm reduction clients, especially among those experiencing barriers to BMT. Offering BMT at harm reduction agencies could improve access to treatment, but studies are needed to determine safety and efficacy of this approach.