bluuebunny/crossref_metadata_2025 huggingface dataset:
The influence of temperament on symptoms and functional outcome in people with psychosis in the Northern Finland 1966 Birth Cohort
Authors: Poustka L. , Murray G.K. , Jääskeläinen E. , Veijola J. , Jones P. , Isohanni M. , Miettunen J.
Published: November 2009

Objective

To describe symptom expression and functional outcome in psychotic disorders in relation with temperament traits assessed with the Temperament and Character Inventory (TCI) in a population-based sample.

Method

As part of the 31-year follow-up survey of the Northern Finland 1966 Birth Cohort, TCI temperament items were filled in by 4349 members of the cohort. In individuals with psychotic disorders, also positive and negative symptoms and outcome variables were assessed in a 35-year follow-up. Information of TCI and outcomes were available for altogether 41 individuals with psychosis.

Result

Reward dependence (RD) (rho = −0.45) and Persistence (P) (rho = −0.52) were significantly correlated with Positive and Negative Syndrome Scale (PANSS) negative symptoms. Higher P scores predicted higher social and occupational functioning (as measured by Social and Occupational Functioning Assessment Scale [SOFAS]), and higher Harm avoidance (HA) predicted a higher likelihood of being on a disability pension.

Conclusion

Results indicate that understanding of personality dimensions support better understanding of outcome and symptom expressions in psychotic disorders.
Topical Steroids in Chronic Rhinosinusitis Without Polyps: A Systematic Review and Meta‐Analysis
Authors: Kalish Larry H. , Arendts Glenn , Sacks Raymond , Craig Jonathan C.
Published: November 2009

OBJECTIVE

To evaluate whether topical steroids provide symptomatic relief in patients with chronic rhinosinusitis without polyps.

DATA SOURCES

MEDLINE, EMBASE, and Cochrane CENTRAL databases.

REVIEW METHODS

Systematic review and meta‐analysis was performed of the articles identified by two independent reviewers of all randomized controlled trials that had evaluated intranasal corticosteroids in patients with chronic rhinosinusitis (CRS) without polyps. The quality of included studies was evaluated, and results synthesized using standard random‐effects meta‐analytical methods.

RESULTS

Of 424 potential studies, only nine randomized trials involving 657 patients in total were eligible. Quality of design and reporting was suboptimal, with only one trial adhering to accepted standards for reporting. Five trials combined outcome measures and reported on overall response of CRS without polyps to topical steroids. The summary estimate for overall response to treatment showed no significant benefit and substantial variability among studies (5 trials: RR 0.75, 95% CI 0.50–1.10, P = 0.14, χ2 = 13.78, I2 = 66.2%). Total symptom score was reported in three trials with a standardized mean difference favoring topical steroids (RR 0.63, 95% CI 0.16–1.09, P = 0.009), with no evidence of heterogeneity (χ2 = 3.03, P = 0.22). Although the data were limited, there were no reports of increased adverse effects with topical steroids.

CONCLUSION

There is insufficient evidence to demonstrate a clear overall benefit for topical steroids in CRS without polyps; however, their use appears safe and may show some symptomatic benefit. A class effect among different topical steroids cannot be assumed, and further trials are required.
Antiemetic Efficacy of Dexamethasone Combined with Midazolam after Middle Ear Surgery
Authors: Yeo Jinseok , Jung Jaesik , Ryu Taeha , Jeon Young Hoon , Kim Sioh , Baek Woonyi
Published: November 2009

OBJECTIVES

To evaluate the antiemetic efficacy of dexamethasone combined with midazolam after middle ear surgery.

STUDY DESIGN

A prospective, randomized, double‐blind, placebo‐controlled study.

SETTING

University hospital.

SUBJECTS AND METHODS

The study population consisted of 120 American Society of Anesthesiologists physical status I or II, adult female patients undergoing middle ear surgery under general anesthesia. Patients were randomized into three groups of 40 each who received a dexamethasone dose of 10 mg/kg (group D), a combination of dexamethasone 10 mg and midazolam 0.075 mg/kg (group DM), and normal saline (group C) immediately after the induction of anesthesia. The incidence of nausea and vomiting, usage of rescue antiemetics, pain intensity, and side effects, such as headache and dizziness, were assessed during the first 24 hours after surgery.

RESULTS

The overall incidence of nausea and vomiting was significantly lower in group D (35%, P < 0.05) and group DM (25%, P < 0.05) compared with that in group C (65%). The incidences of vomiting and usage of rescue antiemetic drugs in group DM were lower than those in group D (P < 0.05). There were no significant differences among groups in pain intensity and side effects, such as headache and dizziness.

CONCLUSIONS

The combination of dexamethasone and midazolam was better than dexamethasone alone in reducing the incidence of vomiting and the rescue antiemetic requirements in women patients undergoing middle ear surgery. However, this combination treatment did not significantly decrease the overall incidence of nausea and vomiting compared with the use of dexamethasone alone.
Ipsilateral and Contralateral Acoustic Brainstem Response Abnormalities in Patients With Vestibular Schwannoma
Authors: Shih Chien , Tseng Fen‐Yu , Yeh Te‐Hei , Hsu Chuan‐Jen , Chen Yuh‐Shyang
Published: November 2009

OBJECTIVE

To analyze auditory brainstem response (ABR) data in patients with vestibular schwannomas (VS) in an effort to identify correlations between abnormal ABR parameters and tumor size.

STUDY DESIGN

Cross‐sectional study with chart review.

SETTING

Tertiary referral hospital.

SUBJECTS AND METHODS

Retrospective chart review and analysis of bilateral ABR records in patients with VS. Interaural latency differences of interpeak I‐V (ILD‐I‐V) and ILD‐V longer than 0.2 ms were used as abnormal criteria.

RESULTS

Thirty patients with a mean age of 50 ± 14 years were included in this study. The most frequent changes in ABR parameters included those of ILD‐I‐V (100%), wave V latency (96.7%), ILD‐V (93.3%), and interpeak I‐V latency (90%). Average VS tumor size was 2.48 ± 1.31 cm. For patients with VS greater than or equal to 2 cm, the prevalences of abnormal ipsilateral interpeak III‐V latency, contralateral wave V latency, and interpeak III‐V latency showed statically significant differences (P = 0.0035, P = 0.0267, and P = 0.0273, respectively) compared to those in patients with VS less than 2 cm. Tumor size was positively correlated with pure‐tone average (P = 0.0106) and with the total number of bilateral abnormal ABR parameters (P = 0.004).

CONCLUSIONS

We identified a correlation between ABR parameters and VS tumor size. An ipsilateral ILD‐I‐V greater than 0.2 ms was sensitive for detecting VS. Abnormal contralateral wave V and interpeak III‐V latency indicated a tumor size potentially larger than 2 cm. Further studies are needed to confirm these findings.
Effect of Temporal Bone Resection on Temporomandibular Joint Function: A Quality if Life Study
Authors: de Casso Carmen , Kwhaja Sadie , Davies Stephen , Al‐Ani Ziad , Saeed Shakeel R. , Homer Jarrod J.
Published: November 2009

OBJECTIVES

Temporal bone resection for carcinoma may affect quality of life (QOL) and result in temporomandibular joint (TMJ) disorders. The aims of this study were to 1) assess TMJ function after temporal bone resection, and 2) assess the impact of TMJ dysfunction on QOL.

STUDY DESIGN

Chart and patient review and QOL study.

SETTING

Tertiary referral center (Manchester Royal Infirmary).

SUBJECTS AND METHODS

Thirty patients who had undergone temporal bone resection were identified. Thirteen patients were alive and were included in the study. All patients were submitted to a clinical examination to identify TMJ disorders and determine facial nerve function, and they all answered the University of Washington QOL (UW‐QOL) questionnaire (version 4).

RESULTS

Eight patients had TMJ disorders with reduced mobility in either direction and/or significant pain. Main factors affecting QOL were pain (P = 0.001), appearance (P = 0.001), and anxiety (P = 0.000). Neither facial nerve palsy nor TMJ disorders affected QOL. The responses to the UW‐QOL questionnaire showed that 69 percent of our patients had a good QOL. A total of 61.53 percent of our patients had TMJ dysfunction presenting as restriction of jaw mobility with or without pain.

CONCLUSION

TMJ dysfunction is present in a significant number of patients after temporal bone resection, resulting in longstanding problems, which should be addressed accordingly. Poor QOL results from ongoing pain and psycho‐social disturbance.
Olfactory Changes after Endoscopic Pituitary Tumor Resection
Authors: Hart Catherine K. , Theodosopoulos Phillip V. , Zimmer Lee A.
Published: November 2009

OBJECTIVES

Given that the transnasal endoscopic approach to the sella involves resection of anatomical structures known to contain olfactory neuroepithelium, the effect of this approach on olfaction was evaluated.

STUDY DESIGN

Case series with planned data collection.

SETTING

Single tertiary care institution.

SUBJECTS AND METHODS

Adults diagnosed with a pituitary mass and scheduled to undergo transnasal endoscopic resection underwent preoperative olfactory evaluation using the University of Pennsylvania Smell Identification Test (UPSIT). Repeat testing was performed at one and three months postoperatively. Paired Student t tests were used to compare preoperative and postoperative scores.

RESULTS

A total of 57 consecutive patients were enrolled. Fifty patients (24 males, 26 females) completed olfactory evaluation at one month. Forty‐five (23 males, 22 females) completed a three‐month evaluation. The average UPSIT score (out of 40) was 31.8 preoperatively, 30.5 at one month, and 32.6 at three months. A significant difference was found between preoperative and one‐month scores (P = 0.01) but not three‐month scores (P = 0.08).

CONCLUSION

A transient difference was found between preoperative and one month UPSIT scores. At three months, no clinically significant difference was found on repeat olfactory testing. Although the transnasal endoscopic approach to the sella removes structures known to contribute to olfactory function, it has no clinically significant effect on olfaction.
Offtaking agreements and how they impact the cost of funding for project finance deals
Authors: Bonetti Veronica , Caselli Stefano , Gatti Stefano
Published: November 2009

Offtaking agreements are an important risk transfer mechanism in project finance. However, they can also be thought of as a trade‐off between lower market and higher counterparty risks. We use the case of the Quezon Power Ltd Co. to test the effect of higher counterparty risk on the cost of funding. Results indicate that the spread of Quezon's bond and counterparty risk are positively correlated when risk is represented by the daily volatility of the offtaker's stock returns. We also find an inverse relation between the rating upgrades of the offtaker and the spread paid by Quezon Power.
Effects of exercise onl-carnitine and lipid metabolism in African catfish (Clarias gariepinus) fed different dietaryl-carnitine and lipid levels
Authors: Ozorio Rodrigo O. A. , Van Ginneken Vincent J. T. , Bessa Rui J. B. , Verstegen Martin W. A. , Verreth Johan A. J. , Huisman Elbertus A.
Published: November 2009

African catfish (Clarias gariepinus) were fed four isonitrogenous diets (34 % crude protein), each containing one of two lipid (100 or 180 g/kg) and twol-carnitine (15 or 1000 mg/kg) levels. After 81 d of feeding, thirty-two fish (body weight 32 g) from each dietary group were randomly selected, sixteen fish were induced to a 3-h swim (speed of 1·5 body length (BL)/s), while the other sixteen fish were kept under resting condition. Fish fed 1000 mgl-carnitine accumulated 3·5 and 5 times morel-carnitine in plasma and muscle, respectively, than fish fed the 15 mgl-carnitine. Musclel-carnitine content was significantly lower in exercised fish than in rested fish. High dietary lipid level (fish oil) led to an increase in musclen-3 PUFA content and a decrease in SFA and MUFA content. In liver, the increase in dietary lipid level resulted in an increased levels of bothn-6 andn-3 PUFA.l-carnitine supplementation significantly decreasedn-3 PUFA content. Exercise decreasedn-3 PUFA in both muscle and liver. Plasma lactate and lactate dehydrogenase, normally associated with increased glycolytic processes, were positively correlated with exercise and inversely correlated with dietaryl-carnitine level.l-carnitine supplementation reduced significantly the RQ from 0·72 to 0·63, and an interaction between dietaryl-carnitine and lipid was observed (P < 0·03). Our results indicate that an increase in fatty acids (FA) intake may promote FA oxidation, and both carnitine and exercise might influence the regulation of FA oxidation selectivity.
Genetic poverty of an extremely specialized wetland species,Nehalennia speciosa: implications for conservation (Odonata: Coenagrionidae)
Authors: Bernard R. , Schmitt T.
Published: November 2009

Oligo- and mesotrophic wetlands, such as bogs, fens and swamps, have become more and more restricted in Europe, and wetland species related to them have increasingly been threatened. Due to increasing habitat fragmentation, the exchange of individuals of these species among sites and, as a consequence, gene flow has been reduced or even eliminated. Therefore, we analysed the genetic structure of 11 populations of an endangered stenotopic damselfly,Nehalennia speciosa(Odonata: Coenagrionidae), in Poland and Lithuania by means of allozyme electrophoresis of 14 gene loci. The overall genetic diversity of all populations was low (A: 1.32;H: 2.6%;Ptot: 29.2%), and no significant differences were observed among the different groupings of populations (degree of fragmentation, habitat type and size, population size). The genetic differentiation among populations was also low (FST: 2.0%) and no regional groups were detected. A low degree of isolation by distance was observed for genetic distances. Taking into account these results, the conservation effort for this species should be focused on large local populations and not necessarily on metapopulation structures. Furthermore,N. speciosacould be (re-)introduced in extinct patches and seemingly suitable localities. Genetically, such relocations should be feasible due to the generally high genetic homogeneity of populations.
Review of the Septibranchia (Pelecypoda: Mollusca) from deep sea of Campos Basin, Brazil: family Verticordiidae, with description of a new species
Authors: de Castro Oliveira Cléo Dilnei , Absalão Ricardo Silva
Published: November 2009

Despite the increase in the number of deep-sea studies, little is known about the hadal molluscs. For Brazil, only a few studies have treated the Septibranchia. This contribution is part of an effort to increase the knowledge of this group off the Brazilian coast, although it is focused only on the Campos Basin (22°S), State of Rio de Janeiro. Four species of the family Verticordiidae are recognized here. ForSpinosipella tingaSimone & Cunha, 2008, the known depth distribution is extended to 1050 m. ForVerticordia woodiiSmith, 1885, previously reported from Brazil, the known distribution is extended southwards to the Campos Basin.Verticordia quadrataSmith, 1885, is reported from Brazil for the first time. A previously unknown species,Verticordia ouricurisp. nov., is described. The presence of small spines, typically with a hexagonal column and a stellate structure at their distal end emerges as an additional taxonomic character for the verticordiids.
Aplysina (Porifera: Demospongiae) species identification through SSCP-ITS patterns
Authors: Lamarão Flávia Rachel M. , Reis Estéfane C. , Simão Tatiana A. , Albano Rodolpho M. , Lôbo-Hajdu Gisele
Published: November 2009

Keratose sponges have no spicules and limited robust morphological characters, causing severe problems for taxonomic classification. Single-strand conformational polymorphism (SSCP) analysis of PCR amplified internal transcribed spacers (ITS) of nuclear ribosomal RNA (rRNA) genes was used to elucidate speciation patterns in marine sponges of the genus Aplysina. In this study, Aplysina species with non-ambiguous traditional morphological alpha taxonomy were used to generate standard SSCP-ITS patterns, which were compared with patterns from alleged new species. Our results show that ITS-SSCP patterns allowed the differentiation of Aplysina sponges, demonstrating the advantage of a method that explores the secondary structure compared to direct sequencing.
Existence and convergence properties of physical measures for certain dynamical systems with holes
Authors: BRUIN HENK , DEMERS MARK , MELBOURNE IAN
Published: November 2009

We study two classes of dynamical systems with holes: expanding maps of the interval and Collet–Eckmann maps with singularities. In both cases, we prove that there is a natural absolutely continuous conditionally invariant measure μ (a.c.c.i.m.) with the physical property that strictly positive Hölder continuous functions converge to the density of μ under the renormalized dynamics of the system. In addition, we construct an invariant measure ν, supported on the Cantor set of points that never escape from the system, that is ergodic and enjoys exponential decay of correlations for Hölder observables. We show that ν satisfies an equilibrium principle which implies that the escape rate formula, familiar to the thermodynamic formalism, holds outside the usual setting. In particular, it holds for Collet–Eckmann maps with holes, which are not uniformly hyperbolic and do not admit a finite Markov partition. We use a general framework of Young towers with holes and first prove results about the a.c.c.i.m. and the invariant measure on the tower. Then we show how to transfer results to the original dynamical system. This approach can be expected to generalize to other dynamical systems than the two above classes.
Non-singular Smale flows on three-dimensional manifolds and Whitehead torsion
Authors: ZHAO XUEZHI
Published: November 2009

This paper deals with non-singular Smale flows on oriented 3-manifolds. We shall show a relation between the properties of invariant sets of a Smale flow and a kind of Whitehead torsion of the underlying manifold.
Partner choice and intergenerational occupational mobility: the case of nineteenth-century rural Sweden
Authors: DRIBE MARTIN , LUNDH CHRISTER
Published: November 2009

This article studies the effects of marriage partner choice on occupational attainment and mobility in five rural parishes in southern Sweden between about 1815 and 1894. It uses an individual-level database containing information on a large number of marriages and the occupational origin of the marrying couple, regardless of whether they were born in the parish or not. Occupations are coded in HISCO and classified using HISCLASS. The results indicate the presence of occupational homogamy in this rural society. The social origin of the partner also mattered a great deal for subsequent occupational attainment and mobility, both upwards and downwards.
Cross, but not direct, presentation of cell‐associated virus antigens by spleen macrophages is influenced by their differentiation state
Authors: Alatery Attiya , Siddiqui Sarah , Chan Matthew , Kus Agnieszka , Petrof Elaine O , Basta Sameh
Published: November 2009

The initiation of T‐cell immune responses requires professional antigen‐presenting cells. Emerging data point towards an important role for macrophages (Mϕ) in the priming of naïve T cells. In this study we analyzed the efficiency and the mechanisms by which Mϕ derived from spleen (Sp‐Mϕ) or bone marrow (BM‐Mϕ) present Lymphocytic choriomeningitis virus (LCMV) antigens to epitope‐specific T cells. We demonstrate that because of phagosomal maturation, Sp‐Mϕ downregulate their ability to cross‐present cell‐associated, but not soluble, antigens, as they are further differentiated in culture without altering their capacity to directly present virus antigens after infection. We propose that Sp‐Mϕ are extremely efficient at direct and cross‐presentation. However, if these cells undergo further M‐CSF‐dependent maturation, they will adapt to be more scavenger and phagocytic and concurrently reduce their cross‐presenting capacity. Accordingly, Sp‐Mϕ can have an important role in regulating T‐cell responses through cross‐presentation depending on their differentiation state.
The natural killer cell: a further innate mediator of gouty inflammation?
Authors: Empson Victoria G , McQueen Fiona M , Dalbeth Nicola
Published: November 2009

Natural killer (NK) cells are vital effector cells of innate immunity because of their rapid cytotoxic and cytokine‐producing responses to cell stress or infection. A distinguishing feature of NK cells is the ability to balance these signals with those of normal homeostasis through the expression of an array of inhibitory and activating receptors. Two functional subsets of NK cells exist: the more mature CD56dimpopulation is potently cytotoxic, whereas CD56brightNK cells have low cytotoxicity but produce much greater amounts of cytokines, and express homing molecules for secondary lymphoid organs and sites of inflammation. NK cells have been identified as important modulatory cells in shaping adaptive immune responses by interacting with dendritic cells (DCs) and T cells. NK cells also interact with cells of the innate immune system such as monocytes and macrophages. This review outlines the biology of NK cells and the potential role of NK cells in modulating gouty inflammation.
Assessment Methodology for Performing Regulatory Due Diligence Based on a Quantitative Approach
Authors: Mladenov Andrey , Maslarova Yuliana , Petkova Eleonora , Mitova Anna
Published: November 2009

Regulatory due diligence is an essential part of every assessment when it comes to mergers, transfer of regulatory licenses, co-development of products or other business activities in the pharmaceutical sector. So far, there is no uniform standard for a quality assessment of registration dossiers. The usual approach is based on a written description of the deficiencies found with eventual recommendations for corrective measures. We propose a newly developed assessment system, applied mainly to generic type of dossiers based on semi-quantitative criteria with weight factors and scores. The reasons for development of this system root in the regulatory harmonization process in Sopharma during the accession of Bulgaria to the European Union (EU). The important advantages provided by our system can also be found in the measurement of efforts put in the dossier upgrade, for example comparing the initial and final scores. The analysis of the score could provide a reliable reference point for the real value of a registration file, as well as its potential for improvement.
Maximizing Neumann fundamental tones of triangles
Authors: Laugesen R. S. , Siudeja B. A.
Published: November 2009

We prove sharp isoperimetric inequalities for Neumann eigenvalues of the Laplacian on triangular domains. The first nonzero Neumann eigenvalue is shown to be maximal for the equilateral triangle among all triangles of given perimeter, and hence among all triangles of given area. Similar results are proven for the harmonic and arithmetic means of the first two nonzero eigenvalues.
Electromechanical characterization of carbon nanotubes grown on carbon fiber
Authors: Patton Steven T. , Zhang Qiuhong , Qu Liangti , Dai Liming , Voevodin Andrey A. , Baur Jeff
Published: November 2009

Mechanical and electrical properties of carbon fiber (CF) and vertically aligned carbon nanotubes (CNTs) have been thoroughly investigated in previous studies. Growth of radially aligned CNTs on silicon oxide (SiO2) coated CF has recently been accomplished resulting in multiscale composite fiber (CNT/SiO2/CF). CNT/SiO2/CF offers promise as stress and strain sensors in CF reinforced composite materials. However, to date there have been no investigations of the electromechanical properties of CNT/SiO2/CF that would facilitate their usage as sensors in composite materials, which is the focus of this research. This study investigates fundamental mechanical and electrical properties of CF, SiO2/CF (SiO2 coated CF), and CNT/SiO2/CF during localized transverse compression at low loads (μN to mN) and small displacements (nm to a few μms). Force, strain, stiffness, and electrical resistance were monitored simultaneously during compression experiments. For CF, resistance decreased sharply upon compressive loading with hysteresis in both force and resistance being observed at low strain. For SiO2/CF, high resistance and negligible electrical conduction occurred, and the force-displacement curve was linear. CNT/SiO2/CF stiffness increased as force and strain increased and became comparable to that of CF at high strain (∼30%). Hysteresis in both force-displacement and resistance-displacement curves was observed with CNT/SiO2/CF, but was more evident as maximum strain increased and did not depend on strain rate. Force was higher and resistance was lower during compression as compared to decompression. Hysteretic energy loss is associated with internal friction between entangled CNTs. Van der Waals force between deformed and entangled CNTs hindered disentanglement, which reduced the number of electrical current paths and increased resistance during decompression. The results of this study provide new understanding of the mechanical and electrical behavior of CNT/SiO2/CF that will facilitate usage as stress and strain sensors in both stand-alone and composite materials applications.
Exchange bias of Co nanoparticles embedded in Cr2O3 and Al2O3 matrices
Authors: Tobia D. , Winkler E. , Zysler R. D. , Granada M. , Troiani H. E. , Fiorani D.
Published: November 2009

The magnetic properties of ∼1.5 nm Co nanoparticles embedded in a diamagnetic Al2O3 or antiferromagnetic (AFM) Cr2O3 matrix were investigated. For Co nanoparticles in Al2O3 matrix, a typical behavior of weakly interacting nanoparticles is observed, characterized by a superparamagnetic regime and a progressive blocking of particle moments centered at ⟨TB⟩=14 K. On the other hand, when the Co nanoparticles are immersed in a Cr2O3 matrix a very different magnetic behavior was found. The system shows large irreversibility in field-cooling/zero-field-cooling magnetization curves and much larger coercivity was observed even up to room temperature. Hysteresis loop shift is present when the system is field-cooled from a temperature above the Cr2O3 Néel temperature. We found that the exchange bias field follows a Brillouin type temperature dependence and goes to zero at TN. These results evidence the enhancement of thermal stability of the Co nanoparticle moments, associated to the increase of anisotropy due to the interface exchange interaction between the ferromagnetic particles and the AFM Cr2O3 matrix.
In situ measurement of surface potential developed on MgO thin film surface under ion irradiation using ion scattering spectroscopy
Authors: Nagatomi T. , Kuwayama T. , Yoshino K. , Takai Y. , Morita Y. , Nishitani M. , Kitagawa M.
Published: November 2009

The application of ion scattering spectroscopy (ISS) to the in situ measurement of the surface potential developed on an insulator surface under positive ion irradiation was investigated. The ISS spectra measured for a MgO film of 600 nm thickness on a Si substrate by the irradiation of 950 eV He+ ions revealed that the surface is positively charged by approximately 180 V. For accurate measurement of the surface potential, a correction to take into account the angular deflection of primary ions induced by the high surface potential is required. The dependence of the surface potential on the sample temperature revealed that no charging is induced above 700 °C, indicating that accumulated charges can be removed by heating to 700 °C. From the measurement of the ion-induced secondary electron yield using a collector electrode located in front of the sample surface, the surface potential and ion-induced secondary electron yield were found to be strongly affected by the experimental setup. Secondary electrons produced by the impact of slow positive secondary ions, the maximum energy of which corresponds to the surface potential, play an important role when the bias voltage applied to the collector electrode is positively high for the present experimental setup. The surface potential developed on the surface of MgO films of 600 and 200 nm thickness was measured in situ, revealing that the amount of accumulated charges and the time required to attain the steady state of charging are slightly dependent on the beam current of primary ions and strongly dependent on the thickness of the MgO film. The present results confirmed that the application of ISS has high potential for investigating charging phenomena and the secondary electron emission from insulator surfaces under positive ion irradiation.
Auto-oscillation and narrow spectral lines in spin-torque oscillators based on MgO magnetic tunnel junctions
Authors: Devolder T. , Bianchini L. , Kim Joo-Von , Crozat P. , Chappert C. , Cornelissen S. , Op de Beeck M. , Lagae L.
Published: November 2009

We demonstrate spin-torque induced coherent auto-oscillation in magnetic tunnel junctions of composition PtMn/CoFe/Ru/CoFeB/MgO/CoFeB and of low resistance-area product. At the generation threshold, we observe a strong line narrowing down to 6 MHz at 300 K and a dramatic increase in oscillator power, yielding spectrally pure oscillations with extremely low flicker noise. The induced auto-oscillations are observed even at zero applied field. The frequency of the oscillation mode, and its dependence with easy and hard axis fields are consistent with an acoustical excitation of the two layers of the synthetic ferrimagnet subsystem. Setting the synthetic ferrimagnet into auto-oscillation requires the current polarity that transfers electrons from the synthetic ferrimagnet to the free layer. In auto-oscillation mode, line jitter is observed such that it is the line envelope that is measured in most cases. The line properties for applied fields near the instability boundaries of the Stoner astroid of the free layer indicate that the phase coherence of the auto-oscillation is likely to be affected by the free layer magnetic noise.
Microwave electromagnetic properties of multiwalled carbon nanotubes filled with Co nanoparticles
Authors: Yi Haibo , Wen Fusheng , Qiao Liang , Li Fashen
Published: November 2009

Multiwalled carbon nanotubes filled with face centered cubic Co nanoparticles (MWCNTs/Co) were successfully prepared by a chemical reducing method. The average outer diameter of MWCNTs is about 40 nm and the size of Co nanoparticles is in the range from 5 to 20 nm. The relative permeability and permittivity spectra of MWCNTs/Co resin composites with 50 wt % powders were measured in the frequency range of 0.1–18 GHz. Three resonance absorption peaks are observed in the μ″−f spectrum: the peak around 5.0 GHz can be attributed to natural resonance, while the other two appear around 10.6 and 16.9 GHz are induced by exchange resonance. It is found that the peak with minimum reflection loss (RL) value moves to lower frequencies and the RL value increases from 4.2 to 10.1 dB with the increase of the absorber’s thickness from 2 to 6 mm.
Slow light at terahertz frequencies in surface plasmon polariton assisted grating waveguide
Authors: Zhang Jing , Cai Likang , Bai Wenli , Xu Yun , Song Guofeng
Published: November 2009

A subwavelength grating waveguide (GW) consisting of two parallel metallic slabs with periodic corrugations on their inner boundaries is developed to slow down the speed of light at terahertz frequencies. Assisted by a tapered input port, our structure has a transfer efficiency of about 80% over a broad bandwidth and strong confinement in the subwavelength scale. Based on the GW, three graded GWs are designed to demonstrate that the spoof surface plasmon polaritons are slowed down and asymptotically stopped when they tend to the location, where the local cutoff frequency is the same as the frequency of the incident light.
Magnetism-induced ferroelectric polarization in the c-axis-oriented orthorhombic HoMnO3 thin films
Authors: Lin T. H. , Hsieh C. C. , Luo C. W. , Lin J.-Y. , Sun C. P. , Yang H. D. , Hsu C.-H. , Chu Y. H. , Wu K. H. , Uen T. M. , Juang J. Y.
Published: November 2009

The magnetism-induced ferroelectricity in the E-type orthorhombic HoMnO3 (o-HMO) films grown on Nb-doped and undoped SrTiO3(001) substrates was studied. The temperature dependent magnetization in these films evidently exhibits an antiferromagnetic ordering around 44K and an anomalous second magnetic ordering along the c-axis near 35K. Interestingly, at this anomalous transition temperature, an associated ferroelectric polarization was probed by the P-E hysteresis measurements, indicating the intimated coupling between the ferroelectric response and the reordering of Mn spins, which has never been disclosed previously by dielectric constant measurements.
Thermodynamics and ferroelectric properties of KNbO3
Authors: Liang Linyun , Li Y. L. , Chen Long-Qing , Hu S. Y. , Lu Guang-Hong
Published: November 2009

The Landau–Ginzburg–Devonshire phenomenological theory is employed to model and predict the ferroelectric phase transitions and properties of single-domain potassium niobate (KNbO3). Based on the LGD theory and the experimental data of KNbO3 single crystal, an eighth-order polynomial of free energy function is proposed. The fitted coefficients are validated by comparing to a set of experimental measured values including phase transition temperatures, spontaneous polarization, dielectric constants, and lattice constants. The effects of hydrostatic pressure and external electric field on phase transition temperatures and piezoelectric coefficients are investigated. The free energy function may be used to predict ferroelectric domain structures and properties of KNbO3 bulk and films by phase-field approach.
Electroluminescence induced by Ge nanocrystals obtained by hot ion implantation into SiO2
Authors: Bregolin F. L. , Behar M. , Sias U. S. , Reboh S. , Lehmann J. , Rebohle L. , Skorupa W.
Published: November 2009

Commonly, electroluminescence (EL) from Ge nanocrystals (Ge NCs) has been obtained by room temperature (RT) Ge implantation into a SiO2 matrix followed by a high temperature anneal. In the present work, we have used a novel experimental approach: we have performed the Ge implantation at high temperature (Ti) and subsequently a high temperature anneal at 900 °C in order to grow the Ge NCs. By performing the implantation at Ti=350 °C, the electrical stability of the MOSLEDs were enhanced, as compared to the ones obtained from RT implantation. Moreover, by changing the implantation fluence from Φ=0.5×1016 and 1.0×1016 Ge/cm2 we have observed a blueshift in the EL emission peak. The results show that the electrical stability of the hot implanted devices is higher than the ones obtained by RT implantation.
Lower and upper estimates on the excitation threshold for breathers in discrete nonlinear Schrödinger lattices
Authors: Cuevas J. , Karachalios N. I. , Palmero F.
Published: November 2009

We propose analytical lower and upper estimates on the excitation threshold for breathers (in the form of spatially localized and time periodic solutions) in discrete nonlinear Schrödinger (DNLS) lattices with power nonlinearity. The estimation, depending explicitly on the lattice parameters, is derived by a combination of a comparison argument on appropriate lower bounds depending on the frequency of each solution with a simple and justified heuristic argument. The numerical studies verify that the analytical estimates can be of particular usefulness, as a simple analytical detection of the activation energy for breathers in DNLS lattices.
The molecular dynamics simulation of ion-induced ripple growth
Authors: Süle P. , Heinig K.-H.
Published: November 2009

The wavelength-dependence of ion-sputtering induced growth of repetitive nanostructures, such as ripples has been studied by molecular dynamics (MD) simulations in Si. The early stage of the ion erosion driven development of ripples has been simulated on prepatterned Si stripes with a wavy surface. The time evolution of the height function and amplitude of the sinusoidal surface profile has been followed by simulated ion-sputtering. According to Bradley–Harper (BH) theory, we expect correlation between the wavelength of ripples and the stability of them. However, we find that in the small ripple wavelength (λ) regime BH theory fails to reproduce the results obtained by molecular dynamics. We find that at short wavelengths (λ<35 nm) the adatom yield drops hence no surface diffusion takes place which is sufficient for ripple growth. The MD simulations predict that the growth of ripples with λ>35 nm is stabilized in accordance with the available experimental results. According to the simulations, few hundreds of ion impacts in λ long and few nanometers wide Si ripples are sufficient for reaching saturation in surface growth for for λ>35 nm ripples. In another words, ripples in the long wavelength limit seems to be stable against ion-sputtering. A qualitative comparison of our simulation results with recent experimental data on nanopatterning under irradiation is attempted.
Spin-polarized transport and the electronic structure of the metallic antiferromagnet Fe(thiazole)2Cl2
Authors: Zhu L. , Yao K. L. , Liu Z. L.
Published: November 2009

We theoretically investigate the electron density of states, band structure, spin polarization, spin filter effect, and current-voltage curve of Fe(thiazole)2Cl2 nanocrystal. The results show that Fe(thiazole)2Cl2 is a metallic antiferromagnet with half-metallic ferromagnetic metastable state. The spin current for the ferromagnetic metastable state shows that Fe(thiazole)2Cl2 has spin-filter property. Moreover, the current-voltage curve exhibits negative differential resistance, which is due to the narrow feature in the density of states of Fe(thiazole)2Cl2. The perfect negative magnetoresistance is also obtained.
A theoretical analysis on characteristics of protein structures induced by cold denaturation
Authors: Oshima Hiraku , Yoshidome Takashi , Amano Ken-ichi , Kinoshita Masahiro
Published: November 2009

Yeast frataxin is a protein exhibiting cold denaturation at an exceptionally high temperature (280 K). We show that the microscopic mechanism of cold denaturation, which has recently been suggested by us [Yoshidome and Kinoshita, Phys. Rev. E 79, 030905–R (2009)], is also applicable to yeast frataxin. The hybrid of the angle-dependent integral equation theory combined with the multipolar water model and the morphometric approach is employed for calculating hydration thermodynamic quantities of the protein with a prescribed structure. In order to investigate the characteristics of the cold-denatured structures of yeast frataxin, we consider the entropy change upon denaturation comprising the loss of the water entropy and the gain in the protein conformational entropy. The minimum and maximum values of the conformational-entropy gain (i.e., the range within which the exact value lies) are estimated via two routes. The range of the water-entropy loss is then determined from the entropy change experimentally obtained [Pastore et al., J. Am. Chem. Soc. 129, 5374 (2007)]. We calculate the water-entropy loss upon the transition from the native structure to a variety of unfolded structures. We then select the unfolded structures for which the water-entropy loss falls within the determined range. The selection is performed at cold and heat denaturation temperatures of yeast frataxin. The structures characterizing cold and heat denaturations are thus obtained. It is found that the average values of the radius of gyration, excluded volume, and water-accessible surface area for the cold-denatured structures are almost the same as those for the heat-denatured ones. We theoretically estimate the cold denaturation temperature of yeast frataxin from the experimental data for the enthalpy, entropy, and heat-capacity changes upon denaturation. The finding is that the temperature is considerably higher than 273 K. These results are in qualitatively good accord with the experimental observations.
Lattice softening for producing ultrahigh strength of iron base nanocrystalline alloy
Authors: Kuramoto S. , Furuta T. , Nagasako N. , Horita Z.
Published: November 2009

One can increase the strength of metallic materials by pinning dislocations with nanoscale obstacles, as the dislocations facilitate plastic deformation. However, simultaneous achievement of the ultrahigh strength and the ductility is extremely difficult in conventional metallic materials. Here we show that the ultrahigh strength iron base alloy with enhanced ductility, whose strength is approaching ideal strength and being twice as much as the upper limit of conventional alloys, can be realized by introducing the paradox concept of lattice softening. Designing atomic arrangement with specific electronic structure creates the lattice softening, and a nanograined structure is then produced by subsequent processing with severe plastic deformation.
The role of intramolecular barriers on the glass transition of polymers: Computer simulations versus mode coupling theory
Authors: Bernabei Marco , Moreno Angel J. , Colmenero Juan
Published: November 2009

We present computer simulations of a simple bead-spring model for polymer melts with intramolecular barriers. By systematically tuning the strength of the barriers, we investigate their role on the glass transition. Dynamic observables are analyzed within the framework of the mode coupling theory (MCT). Critical nonergodicity parameters, critical temperatures, and dynamic exponents are obtained from consistent fits of simulation data to MCT asymptotic laws. The so-obtained MCT λ-exponent increases from standard values for fully flexible chains to values close to the upper limit for stiff chains. In analogy with systems exhibiting higher-order MCT transitions, we suggest that the observed large λ-values arise form the interplay between two distinct mechanisms for dynamic arrest: general packing effects and polymer-specific intramolecular barriers. We compare simulation results with numerical solutions of the MCT equations for polymer systems, within the polymer reference interaction site model (PRISM) for static correlations. We verify that the approximations introduced by the PRISM are fulfilled by simulations, with the same quality for all the range of investigated barrier strength. The numerical solutions reproduce the qualitative trends of simulations for the dependence of the nonergodicity parameters and critical temperatures on the barrier strength. In particular, the increase in the barrier strength at fixed density increases the localization length and the critical temperature. However the qualitative agreement between theory and simulation breaks in the limit of stiff chains. We discuss the possible origin of this feature.
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cluster formation at interfaces with pentacene thin-film phases
Authors: Conrad B. R. , Tosado J. , Dutton G. , Dougherty D. B. , Jin W. , Bonnen T. , Schuldenfrei A. , Cullen W. G. , Williams E. D. , Reutt-Robey J. E. , Robey S. W.
Published: November 2009

The C60-thin film pentacene interface was investigated using scanning tunneling microscopy, atomic force microscopy, and ultraviolet photoemission spectroscopy. C60 deposition on a multilayer pentacene film (standing) yields an interface dominated by C60 clusters, regardless of the underlying substrate. Three-dimensional cluster growth dominates due to weak interactions with the underlying Pn. C60 cluster size and density on sequential Pn layers suggest an Ehrlich–Schwoebel-type barrier at Pn layer boundaries. Cluster formation reduces the C60 lowest unoccupied molecular orbital–Pn highest occupied molecular orbital (HOMO) separation, while increasing the respective HOMO-HOMO offset. Heterostructure fabrication protocols can alter interface morphology and induce band shifts on the order of 0.3 eV.
Defect selective passivation in GaN epitaxial growth and its application to light emitting diodes
Authors: Lo M.-H. , Tu P.-M. , Wang C.-H. , Cheng Y.-J. , Hung C.-W. , Hsu S.-C. , Kuo H.-C. , Zan H.-W. , Wang S.-C. , Chang C.-Y. , Liu C.-M.
Published: November 2009

A defect selective passivation method to block the propagation of threading dislocations in GaN epitaxial growth is demonstrated. The defect selective passivation is done by using defect selective chemical etching to locate defect sites, followed by silicon oxide passivation of the etched pits, and epitaxial over growth. The threading dislocation density in the regrown epilayer is significantly improved from 1×109 to 4×107 cm−2. The defect passivated epiwafer is used to grow light emitting diode and the output power of the fabricated chip is enhanced by 45% at 20 mA compared to a reference one without using defect passivation.
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excitonic splittings and vibronic coupling in the excited state of the jet-cooled 2-aminopyridine dimer
Authors: Ottiger Philipp , Leutwyler Samuel , Köppel Horst
Published: November 2009

We analyze the vibronic band structure of the excitonically coupled S1←S0/S2←S0 excitations of the 2-aminopyridine (2AP) self-dimer (2AP)2, using a linear vibronic coupling model [R. Fulton and M. Gouterman, J. Chem. Phys. 41, 2280 (1964)]. The vibronic spectra of supersonically cooled (2AP)2 and its C13-isotopomer were measured by two-color resonant two-photon ionization and UV/UV-depletion spectroscopies. In the C2-symmetric form of (2AP)2, the S1←S0 (A1←A1) transition is very weak, while the close-lying S2←S0 (B1←A1) transition is fully allowed. A single C12/C13 isotopic substitution breaks the symmetry of the dimer so that the (2AP)2−C13 isotopologue exhibits both S1 and S2 electronic origins, which are split by 11 cm−1. In Fulton–Gouterman-type treatments, the linear vibronic coupling is mediated by intramolecular vibrational modes and couplings to intermolecular vibrations are not considered. For (2AP)2, a major vibronic coupling contribution arises from the intramolecular 6a′ vibration. However, the low-energy part of the spectrum is dominated by intermolecular shear (χ′) and stretching (σ′) vibrational excitations that also exhibit excitonic splittings; we apply a linear vibronic coupling analysis for these also. The respective excitation transfer integrals VAB are 50%–80% of that of the intramolecular 6a′ vibration, highlighting the role of intermolecular vibrations in mediating electronic energy exchange. The S1/S2 electronic energy gap calculated by the approximate second-order coupled-cluster method is ∼340 cm−1. This purely electronic exciton splitting is quenched by a factor of 40 by the vibronic couplings to the Franck–Condon active intramolecular vibrations.
Characterization of the “clean-up” of the oxidized Ge(100) surface by atomic layer deposition
Authors: Milojevic M. , Contreras-Guerrero R. , Lopez-Lopez M. , Kim J. , Wallace R. M.
Published: November 2009

While the “clean-up” effect on III-V substrates has recently been well documented interfacial reactions during atomic layer deposition (ALD) on Ge substrates are not fully explored. The “clean-up” of Ge oxides is studied by interrupting the ALD process following individual precursor pulses for in situ monochromatic x-ray photoelectron spectroscopy analysis. Germanium oxides are found to be reduced by TMA and water, while an interfacial GeON layer is only affected by the initial TMA pulse. Oxide free germanium surfaces behave analogously to a surface with initial native oxides since they are oxidized measurably prior to the first TMA pulse due to residual oxidants in a commercial ALD chamber.