bluuebunny/crossref_metadata_2025 huggingface dataset:
Luminescence of Acceptors in Mg-Doped GaN
Authors: Monemar Bo , Khromov Sergey , Pozina Galia , Paskov Plamen , Bergman Peder , Hemmingsson Carl , Hultman Lars , Amano Hiroshi , Avrutin Vitaliy , Li Xing , Morkoç Hadis
Published: May 2013

Recent photoluminescence (PL) data for Mg-doped GaN at 2 K are discussed, with reference to published theoretical calculations of the electronic level structure. It is concluded that the typical PL peaks at 3.466 eV (acceptor bound exciton ABE1) and the broader 3.27 eV donor–acceptor pair (DAP) PL are the expected standard PL signatures of the substitutional Mg acceptor. Additional broader peaks at 3.455 eV (ABE2) and 3.1 eV are suggested to be related to the same acceptors perturbed by nearby basal plane stacking faults. The low temperature metastability of PL spectra is assigned to a nonradiative metastable deep level.
Investigations of Polarization-Induced Hole Accumulations and Vertical Hole Conductions in GaN/AlGaN Heterostructures
Authors: Yasuda Toshiki , Yagi Kouta , Suzuki Tomoyuki , Nakashima Tsubasa , Watanabe Masahiro , Takeuchi Tetsuya , Iwaya Motoaki , Kamiyama Satoshi , Akasaki Isamu
Published: May 2013

We investigated hole concentrations induced by spontaneous and piezoelectric polarization charges in GaN/AlGaN/GaN heterostructures. An AlN mole fraction dependence reveals that the induced hole concentrations were accurately controlled by the AlN mole fractions up to 0.34 in the GaN/AlGaN/GaN structures. We then demonstrated vertical hole conduction across an undoped graded AlGaN layer and hole injection to an active region in a LED structure to some extent. These results suggest that the controlled polarization charges by AlN mole fractions have potential as an alternative doping method for high hole concentrations in nitride semiconductors.
Unstable Luminescence of Nitrides under Electron-Beam Irradiation
Authors: Kuznetsova Yana , Zamoryanskaya Maria
Published: May 2013

The aim of the work was to study the nature of unstable luminescence of nitride bulk layers and heterostructures under stationery electron beam irradiation. During irradiation increasing of intensity of luminescence was observed. Typical times of this effect are tens up to hundreds of seconds. Details of the effect were studied. It was noticed that in several cases the irradiated by electron beam area was characterized by different luminescence properties even after 24 h at room temperature in vacuum. Several mechanisms leading to increasing of the intensity of luminescence were discussed.
Impact of Diffusivity to Carrier Recombination Rate in Nitride Semiconductors: From Bulk GaN to (In,Ga)N Quantum Wells
Authors: Aleksiejūnas Ramūnas , Ščajev Patrik , Nargelas Saulius , Malinauskas Tadas , Kadys Arūnas , Jarašiūnas Kęstutis
Published: May 2013

We combined light induced transient grating and free carrier absorption techniques to investigate temporal and spatial carrier dynamics in nitrides. Inverse correlation of diffusivity and nonradiative recombination rate in GaN epilayers was ascribed to carrier diffusive flow to the internal boundaries of hexagonal grains and recombination on dislocations there, while the similar dependence in InGaN quantum wells (QWs) was a consequence of carrier delocalization caused either by carrier injection or thermal escape. Numerical modeling of recombination rates in light emitting diode structures with In content up to 13% revealed increasing with excitation nonradiative recombination rate which is a consequence of higher overall carrier mobility at higher densities. We propose the injection-enhanced in-plane diffusivity as the most probable mechanism explaining the increase of non-radiative losses in high power light emitting diodes (LEDs).
Systematic Optical Characterization of Two-Dimensional Electron Gases in InAlN/GaN-Based Heterostructures with Different In Content
Authors: Romero María Fátima , Feneberg Martin , Moser Pascal , Berger Christoph , Bläsing Jürgen , Dadgar Armin , Krost Alois , Sakalauskas Egidijus , Calle Fernando , Goldhahn Rüdiger
Published: May 2013

Model calculations have been performed to study systematically the formation of a two-dimensional electron gas (2DEG). The results are used for analyzing the photoluminescence properties of corresponding InAlN/GaN heterostructures (HS) for various In concentrations (x= 6.7–20.8%). We found a luminescence peak, clearly dependent on the In content, that is attributed to the recombination between electrons in the 2DEG at the second level (En=2) and photoexcited holes in the GaN buffer. The results can be understood with the changing band profile attributed to the different polarization gradient between InAlN and GaN.
Photoelectrochemical Fabrication of Porous GaN and Their Applications in Ultraviolet and Ammonia Sensing
Authors: Beh Khi Poay , Yam Fong Kwong , Tan Lay Kim , Ng Siow Woon , Chin Che Woei , Hassan Zainuriah
Published: May 2013

This article reports the studies of porous GaN fabricated using photo-electrochemical anodization method and their applications in UV and ammonia gas sensing. GaN was anodized under different durations and their fundamental aspects were investigated. Electron micrographs revealed that the porous surface was obtained, however prolonged anodization durations would lead to breakdown of porous layer, forming nanostructures. A plausible pore formation and breakdown mechanism were proposed based on current-transient profile. In Raman spectroscopy, forbidden bands such as E1(TO) and A1(TO) were noted in anodized samples. The intensity of these bands was dependent on the geometrical position of the nanostructures formed on porous surface. In UV and ammonia sensing studies, change in Schottky barrier height was the greatest for anodized samples. Porous GaN in UV sensing was 5 times more sensitive relative to as-grown GaN. In ammonia sensing, porous GaN displayed positive results even in the absence of catalytic metal, Pt.
Proposal of New Measurement Method for Internal Quantum Efficiency of Light-Emitting Diodes
Authors: Ma Byungjin , Lee Kwanhoon
Published: May 2013

A new evaluation method for effective internal optical power (IOP) and internal quantum efficiency (IQE) of light-emitting diodes (LEDs) is demonstrated. This method is based on the optical and thermal properties of LEDs. By using this proposed method, the effective IOP and the IQE of LEDs could be directly extracted from the measurements of external optical power (EOP) and junction temperature of LEDs. This method needs no assumption of the injection efficiency of carriers in the LEDs and no measurement-condition limitation of low current-injection level.
Splitting of the Surface Phonon Modes in Wurtzite Nanowires
Authors: Cros Ana , Wang Jiangfeng , Demangeot François , Péchou Renaud , Daudin Bruno
Published: May 2013

We analyze the surface optical modes of GaN nanowires (NW) and perform a comparative study with the characteristics expected for other polar NWs. The theoretical analysis of the modes is performed within the context of the effective medium theory that takes into account the dipolar interaction between neighboring NWs (Maxwell-Garnett approximation). It is shown that deviations of the exciting light from the NWs axis, which coincides with the wurtzite c-axis, result in the anticrossing of two distinct surface phonon branches, leading to their splitting in axial and planar components and the appearance of two peaks in the Raman spectra. Additional calculations are performed that determine the relevant filling factor at which this anticrossing takes place for NWs based on AlN, InN, ZnO, as well as other material systems that may crystallize in the wurtzite structure when grown in the form of NWs, such as GaP and InAs. We analyze the splitting of the surface modes as a function of the material's ionicity.
Temperature Dependent Photoluminescence Excitation Spectroscopy of GaN Quantum Dots in Site Controlled GaN/AlGaN Nanowires
Authors: Holmes Mark J. , Kako Satoshi , Choi Kihyun , Podemski Pawel , Arita Munetaka , Arakawa Yasuhiko
Published: May 2013

Photoluminescence excitation spectroscopy is performed on a single GaN quantum dot embedded in a core shell type GaN/AlGaN nanowire. The temperature dependence of the photoluminescence excitation spectrum is presented, revealing the expected temperature dependent shift in both the exciton ground and excited states. The states are further characterised by comparison to 8-band k·p calculations.
Exciton–Exciton Interactions in Tensile-Strained GaN
Authors: Toda Yasunori , Shigematsu Kyohhei , Hasegawa Akira , Adachi Satoru
Published: May 2013

We report on the four-wave mixing (FWM) spectroscopy of excitons in tensile-strained GaN films. Three excitonic resonances (A-, B-, and C-excitons) were clearly observed with energy separations of ΔAB∼4.7 meV and ΔBC∼14.5 meV. Owing to tensile strain, these values are much smaller than those of free-standing GaN, allowing the simultaneous excitations of A–B and B–C excitons pairs. The time evolutions of the FWM in different polarization configurations resolved the differences in the simultaneous excitonic transitions; the excitation of A–B excitons showed an oscillation with a critical π-phase shift in the orthogonal polarization configuration as expected in the quantum beat, and the oscillation of B–C excitons pair is independent of the polarization configuration, indicating polarization interference. The polarization-dependent FWM spectra of A–B excitons revealed peaks associated with biexciton transitions with binding energies of E
AA = 4.6 meV, E
AB = 2.1 meV, and E
BB = 1.7 meV.
Theoretical Studies of the Influence of Temperature on Photoluminescence Dynamics in GaInNAs/GaAs Quantum Wells
Authors: Baranowski Michał , Kudrawiec Robert , Misiewicz Jan
Published: May 2013

Dynamics of excitons in GaInNAs/GaAs quantum wells (QWs) is studied theoretically within a model of hopping excitons. In this model the temporal evolution of photoluminescence (PL) is described by the system of rate equations which takes into account hopping of excitons between randomly generated localizing states. In this work we study the influence of temperature on such characteristic features of PL as the decay and rise time of PL signal as well as their spectral dependences. It is clearly shown that our model reproduces experimental data very well.
Quantum Confinement in Thin GaN Cap Layers Deposited on AlGaN/GaN Heterostructures: The Issue of Polar Surface Quantum Well
Authors: Gladysiewicz Marta , Kudrawiec Robert
Published: May 2013

The quantum confinement in Ga- and N-polar GaN surface quantum well (SuQW) formed on AlGaN/GaN heterostructures is calculated within the effective mass approximation. The influence of surface roughness and content fluctuation in AlGaN barrier are taken into account within the model of random QW [M. Gladysiewicz and R. Kudrawiec: J. Phys.: Condens. Matter 22 (2010) 485801]. Obtained results are discussed in the context of available experimental data for this material system. It is clearly shown that the observation of quantum confinement for GaN SuQW (i.e., the optical transition at higher energy than GaN energy gap) is a clear evidence of good homogeneity of the investigated heterostructures. Such a transition should be expected for AlGaN/GaN heterostructures with the GaN cap thinner than ∼3 nm.
Cathodoluminescence Study of Optical Inhomogeneity in Si-Doped AlGaN Epitaxial Layers Grown by Low-Pressure Metalorganic Vapor-Phase Epitaxy
Authors: Kurai Satoshi , Ushijima Fumitaka , Yamada Yoichi , Miyake Hideto , Hiramatsu Kazumasa
Published: May 2013

We have investigated the effects of Si doping on the microscopic optical inhomogeneity of Al0.61Ga0.39N epitaxial layers through the combined use of scanning electron microscopy (SEM) and cathodoluminescence (CL). Hexagonal hillocks and corresponding CL inhomogeneity in AlGaN epitaxial layers were observed in SEM and CL images, respectively, and the density of such structures increased with increasing the Si concentration. CL spectra of Si-doped AlGaN epitaxial layers taken at 80 K showed near-band-edge emission around 4.9 eV and an emission line around 4.4 eV. Monochromatic CL images of Si-doped AlGaN at the detection energy of 4.4 eV appeared selectively at the edges of hexagonal hillocks, indicating selective incorporation of Si atoms into defects at grain boundaries.
Design and Simulation of Novel Enhancement Mode 5–20 kV GaN Vertical Superjunction High Electron Mobility Transistors for Smart Grid Applications
Authors: Li Zhongda , Chow T. Paul
Published: May 2013

We report on the design, simulations and optimization of a novel enhancement mode 5–20 kV GaN vertical superjunction (SJ) high electron mobility transistor (HEMT). We optimize the space charge in GaN pillars using GaN SJ p–n diode for the best trade-off between breakdown voltage (BV) and specific on-resistance (R
onsp), by varying the pillar dosage, length and width. The resulting GaN SJ field effect transistor (FET) structure is projected to have, for example, R
onsp of 4.2 mΩ cm2 with BV of 12.4 kV.
Enhancement-Mode LaLuO3–AlGaN/GaN Metal–Insulator–Semiconductor High-Electron-Mobility Transistors Using Fluorine Plasma Ion Implantation
Authors: Yang Shu , Huang Sen , Schnee Michael , Zhao Qing-Tai , Schubert Jürgen , Chen Kevin J.
Published: May 2013

In this work, enhancement-mode (E-mode) AlGaN/GaN metal–insulator–semiconductor high-electron-mobility transistors (MIS-HEMTs) with high-κ LaLuO3(LLO) gate dielectric were fabricated by deploying the CF4plasma treatment technique in a gate-dielectric-first planar process. CF4plasma treatment can shift the threshold voltage from -2.3 V [for depletion-mode (D-mode) LLO MIS-HEMTs] to 0.6 V (for E-mode LLO MIS-HEMTs). Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) results suggest that fluorine ions could penetrate through the polycrystalline/amorphous LLO film and be implanted into the (Al)GaN barrier layer. The primary threshold voltage (VTH) shift mechanism of the E-mode LLO MIS-HEMTs is the negatively-charged fluorine ions in (Al)GaN, while fluorine atoms form chemical bonds with La/Lu atoms in the fluorinated LLO film. The E-mode LLO MIS-HEMTs exhibit a drive drain current density of 352 mA/mm atVGS= 2.5 V and a peak transconductance (Gm) of ∼193 mS/mm. Significant suppression of current collapse and low dynamic ON-resistance are obtained in the E-mode LLO MIS-HEMTs under high-drain-bias switching conditions.
Avalanche Breakdown Design Parameters in GaN
Authors: Li Zhongda , Pala Vipindas , Chow T. Paul
Published: May 2013

We have studied the avalanche breakdown design parameters of GaN n+/p and p+/n junctions in the voltage range of 1.2 to 12 kV using numerical simulations and analytical calculations. Important analytical models regarding the relationships between breakdown voltages, depletion width, maximum junction electric field and doping concentrations have been extracted which shows very high consistency with the results from numerical simulations. These analytical models can be used as guidelines in the designing of GaN high voltage power devices. The multiplication factors M
n and M
p have also been obtained and the analytical models have been extracted. The results showed that in GaN, n+/p junction is better than p+/n for the main voltage blocking junction due to a sharper avalanche current increase.
Evaluation of the Initial Stage of Formation of Ti/Al Ohmic Contacts Using Photoresponse Method
Authors: Shiojima Kenji , Yokohama Hideo , Araki Gako
Published: May 2013

Ti/Al contacts formed on n-GaN and AlGaN/GaN layers upon annealing at temperatures below the melting point of Al were evaluated by photoresponse (PR), current–voltage (I–V), and secondary ion mass spectroscopy (SIMS) measurements. In the PR spectra, the photocurrent based on the internal photoemission was detected, and the Schottky barrier height (qφB) was determined for all the samples, even though the I–V characteristics were very leaky. The AlGaN/GaN samples had constant qφB values of 0.85–1.0 eV independent of the annealing temperature. In contrast, the n-GaN samples had very low qφB values of 0.2 eV under the as-deposited condition. Upon annealing, qφB significantly increases and finally reaches almost the same values as those of the AlGaN/GaN samples. This can be explained by the change from Ti- to Al-rich interfaces in conjunction with the SIMS results.
Control of Threshold Voltage in GaN Based Metal–Oxide–Semiconductor High-Electron Mobility Transistors towards the Normally-Off Operation
Authors: Ťapajna Milan , Kuzmík Ján
Published: May 2013

The effect of defect charges on a threshold voltage (V
th) of the GaN/AlGaN/GaN metal–oxide–semiconductor heterostructures (MOS-Hs) with the gate stack thickness scaling was investigated by using capacitance–voltage measurements and a comprehensive analytical model [M. Ťapajna and J. Kuzmík: Appl. Phys. Lett. 100 (2012) 113509]. Using the MOS-Hs with Al2O3 and HfO2 dielectrics grown by plasma-enhanced atomic layer deposition, a high density (∼1013 cm-2) of negative fixed oxide charge (N
ox) was extracted for Al2O3 layers, while an order of magnitude lower density (∼1012 cm-2) of positive N
ox was extracted for HfO2 films. Consequently, despite similar dielectric constant of Al2O3 to that of (Al)GaN, it is advisable to attain normally-off operation by scaling the AlGaN layer thickness rather than the oxide thickness, taking advantage of the negative N
ox offsetting V
th towards the positive voltages. Scaling of the AlGaN layer thickness is found to be effective also in the case of HfO2 dielectric, however, due to a positive N
ox in HfO2, AlGaN layer needs to be scaled to a similar thickness (e.g., ∼3 nm) to obtain a positive V
th for the same oxide thickness of HfO2 and Al2O3 (∼5 nm). On the other hand, scaling of the GaN cap has no effect on V
th. Further, our analysis suggests that for MOS-Hs with both Al2O3 and HfO2 gate dielectric, the Fermi level position at the oxide/barrier interface in equilibrium is located within donor-like interface traps. Therefore, the oxide/GaN cap interface trap charge in MOS-Hs with the given structure parameters should lead to a negative V
th shift.
Optical-Thermo-Transition Model of Reduction in On-Resistance of Small GaN p–n Diodes
Authors: Mochizuki Kazuhiro , Mishima Tomoyoshi , Nomoto Kazuki , Terano Akihisa , Nakamura Tohru
Published: May 2013

The forward current (I
F) of GaN p–n diodes forward biased at 5 V was found to be proportional to anode perimeter and independent of temperature (273–373 K). Although this I
F characteristic contributes to reduction in specific on-resistance (R
on
A) of small GaN p–n diodes, the mechanism involved is yet to be understood. Accordingly, in this study, an optical-thermo-transition model for the reduced R
on
A in small GaN p–n diodes is proposed. The energy of photons that are created through radiative recombination around the edge of anode electrode is considered to be used for optical-thermo-transition; that is, electrons are emitted from ionized acceptors to conduction bands, and the resultant neutralized acceptors are ionized through electron capture from valence bands. Since known self-heating and intrinsic-photon-recycling effects are considered to be negligible, optical-thermo transition and enhanced radiative recombination (due to large perimeter-to-area ratio) are concluded to play a dominant role in reducing R
on
A.
New Chinese Accounting Standards and the Usefulness of Accounting Information in Debt Contracts
Authors: Yuan Hongqi , Li Yubo , Lou Fang , Zhang Yao
Published: May 2013

This paper investigates whether the usefulness of accounting profitability in debt contracts changes after the adoption of the new Chinese accounting standards (“NCAS”) in 2007. We find that the sensitivity of new debts to accounting profitability declines after the adoption and that firms are heavily influenced by the adoption of the new accounting standards and experience a more significant decrease in sensitivity. Moreover, such a decrease in sensitivity is more pronounced for non-state-owned companies than for state-owned companies. Overall, our results indicate that the usefulness of accounting profitability decreases after the adoption of the new accounting standards.
Reuse and Recycle: The Development of Adaptive Expertise, Routine Expertise, and Novelty in a Large Research Team
Authors: Paletz Susannah B. F. , Kim Kevin H. , Schunn Christian D. , Tollinger Irene , Vera Alonso
Published: May 2013

Combining innovation and efficiency is ideal in many organizational settings. Adaptive expertise represents a cognitive explanation of how individuals and teams can learn to achieve simultaneous innovation and efficiency. In 2004, scientists led twin rovers on Mars in the search for historical water. The science team experienced a remarkable increase in efficiency, adapting with flexibility to unexpected events and dynamic, dwindling resources. After discussing the conceptual differences between adaptive expertise and related team learning and innovation concepts, we examine longitudinal behavioral data on novelty, routine and adaptive expertise. Sequential time series ARIMA analyses reveal that novelty fluctuated randomly, but both routine and adaptive expertise significantly increased over time. In addition, novelty, routine expertise, and adaptive expertise did not significantly predict each other directly or at a lag, suggesting that these are indeed three distinct constructs. Implications for theory and research on efficiency and innovation are discussed. Copyright © 2013 John Wiley & Sons, Ltd.
Whole‐exome sequencing identified a homozygous FNBP4 mutation in a family with a condition similar to microphthalmia with limb anomalies
Authors: Kondo Yukiko , Koshimizu Eriko , Megarbane Andre , Hamanoue Haruka , Okada Ippei , Nishiyama Kiyomi , Kodera Hirofumi , Miyatake Satoko , Tsurusaki Yoshinori , Nakashima Mitsuko , Doi Hiroshi , Miyake Noriko , Saitsu Hirotomo , Matsumoto Naomichi
Published: May 2013

Microphthalmia with limb anomalies (MLA), also known as Waardenburg anophthalmia syndrome or ophthalmoacromelic syndrome, is a rare autosomal recessive disorder. Recently, we and others successfully identified SMOC1 as the causative gene for MLA. However, there are several MLA families without SMOC1 abnormality, suggesting locus heterogeneity in MLA. We aimed to identify a pathogenic mutation in one Lebanese family having an MLA‐like condition without SMOC1 mutation by whole‐exome sequencing (WES) combined with homozygosity mapping. A c.683C>T (p.Thr228Met) in FNBP4 was found as a primary candidate, drawing the attention that FNBP4 and SMOC1 may potentially modulate BMP signaling. © 2013 Wiley Periodicals, Inc.
Grooming reciprocity in male Tibetan macaques
Authors: Xia Dong‐Po , Li Jin‐Hua , Garber Paul A. , Matheson Megan D. , Sun Bing‐Hua , Zhu Yong
Published: May 2013

In several primate species, adult males are reported to compete for access to reproductive partners as well as forming affiliative and cohesive social bonds based on the exchange of goods or services. We hypothesized that among a broad set of fitness‐maximizing strategies, grooming can be used by individual adult males to enhance social relationships through reciprocity and/or through the interchange of grooming for a different but equivalent good or service. We used focal animal sampling and continuously recorded dyadic grooming and agonistic interactions to test a series of predictions regarding male social interactions in a free‐ranging group of Tibetan macaques (Macaca thibetana) at Huangshan, China. During the non‐mating season or between males of similar rank throughout the year, grooming effort given was matched by grooming effort received. However, lower ranking males groomed higher ranking males at a greater rate and/or for a longer duration during both the mating and non‐mating periods. We found that higher ranking males directed less aggression towards males with whom they formed a frequent grooming partnership, indicating that grooming received was interchanged for increased social tolerance. These data suggest that individual male Tibetan macaques employ alternative social strategies associated with grooming reciprocity or interchange depending on dominance rank and rates of aggression, and highlight the importance of both biological markets and grooming reciprocity as behavioral mechanisms used by resident adult males to form and maintain affiliative social bonds. Am. J. Primatol. 75:1009–1020, 2013. © 2013 Wiley Periodicals, Inc.
Effect of intranasal budesonide irrigations on intraocular pressure
Authors: Seiberling Kristin A. , Chang Dennis F. , Nyirady Janice , Park Francine , Church Christopher A.
Published: May 2013

Background

Intranasal and oral corticosteroids are widely used in the management of chronic rhinosinusitis with nasal polyps (CRSwNP). Higher‐dose topical nasal steroids (HDTNS) such as budesonide irrigations are increasingly used for long‐term maintenance in these patients. Oral steroids have the potential to cause increased intraocular pressure (IOP) and glaucoma. It is unclear whether HDTNS have the same potential. The objective of this study was to determine the effect of intranasal budesonide irrigations on IOP.

Methods

Two groups of patients with CRSwNP treated with budesonide irrigations were prospectively enrolled. Patients with history of elevated IOP or glaucoma were excluded. Patients in group 1 had been using budesonide for at least 1 month and had IOP measured once at the time of enrollment. Group 2 consisted of patients who were placed on budesonide at the time of enrollment and had IOP measured both before and after at least 4 weeks of therapy.

Results

Ten patients in group 1 and 8 patients in group 2 completed the study. In group 1, the average duration of therapy at enrollment was 6.3 months (1–22 months). Only 1 patient had a single eye pressure above 21 mmHg. None of the patients in group 2 had a significant change in IOP or IOP over 21 mmHg.

Conclusion

Intranasal budesonide irrigations given for a period of at least 1 month do not appear to increase IOP.
Mild cognitive impairment due to Alzheimer disease in the community
Authors: Petersen Ronald C. , Aisen Paul , Boeve Bradley F. , Geda Yonas E. , Ivnik Robert J. , Knopman David S. , Mielke Michelle , Pankratz Vernon S. , Roberts Rosebud , Rocca Walter A. , Weigand Stephen , Weiner Michael , Wiste Heather , Jack Clifford R.
Published: May 2013

Objective

The newly proposed National Institute on Aging–Alzheimer's Association (NIA‐AA) criteria for mild cognitive impairment (MCI) due to Alzheimer disease (AD) suggest a combination of clinical features and biomarker measures, but their performance in the community is not known.

Methods

The Mayo Clinic Study of Aging (MCSA) is a population‐based longitudinal study of nondemented subjects in Olmsted County, Minnesota. A sample of 154 MCI subjects from the MCSA was compared to a sample of 58 amnestic MCI subjects from the Alzheimer's Disease Neuroimaging Initiative 1 (ADNI‐1) to assess the applicability of the criteria in both settings and to assess their outcomes.

Results

Fourteen percent of MCSA and 16% of ADNI‐1 of subjects were biomarker negative. In addition, 14% of MCSA and 12% of ADNI‐1 subjects had evidence for amyloid deposition only, whereas 43% of MCSA and 55% of ADNI‐1 subjects had evidence for amyloid deposition plus neurodegeneration (magnetic resonance imaging atrophy, fluorodeoxyglucose positron emission tomography hypometabolism, or both). However, a considerable number of subjects had biomarkers inconsistent with the proposed AD model; for example, 29% of MCSA subjects and 17% of ADNI‐1 subjects had evidence for neurodegeneration without amyloid deposition. These subjects may not be on an AD pathway. Neurodegeneration appears to be a key factor in predicting progression relative to amyloid deposition alone.

Interpretation

The NIA‐AA criteria apply to most MCI subjects in both the community and clinical trials settings; however, a sizeable proportion of subjects had conflicting biomarkers, which may be very important and need to be explored. Ann Neurol 2013;74:199–208
Mutations in TNK2 in severe autosomal recessive infantile onset epilepsy
Authors: Hitomi Yuki , Heinzen Erin L. , Donatello Simona , Dahl Hans‐Henrik , Damiano John A. , McMahon Jacinta M. , Berkovic Samuel F. , Scheffer Ingrid E. , Legros Benjamin , Rai Myriam , Weckhuysen Sarah , Suls Arvid , De Jonghe Peter , Pandolfo Massimo , Goldstein David B. , Van Bogaert Patrick , Depondt Chantal
Published: May 2013

We identified a small family with autosomal recessive, infantile onset epilepsy and intellectual disability. Exome sequencing identified a homozygous missense variant in the gene TNK2, encoding a brain‐expressed tyrosine kinase. Sequencing of the coding region of TNK2 in 110 patients with a similar phenotype failed to detect further homozygote or compound heterozygote mutations. Pathogenicity of the variant is supported by the results of our functional studies, which demonstrated that the variant abolishes NEDD4 binding to TNK2, preventing its degradation after epidermal growth factor stimulation. Definitive proof of pathogenicity will require confirmation in unrelated patients. Ann Neurol 2013;74:496–501
Rigid polyurethane foams modified with selected layered silicate nanofillers
Authors: Danowska Magdalena , Piszczyk Łukasz , Strankowski Michał , Gazda Maria , Haponiuk Józef T.
Published: May 2013

The aim of this study was to investigate the effect of three different nanofillers on the properties of rigid polyurethane foams, which were prepared by a one‐step, laboratory‐scale method from a two‐component system at the ratio of NCO groups to OH groups equaled to 2. The reaction mixture consisted of the proper amounts of the commercial oligoether polyol, catalysts, water, nanoclays, and polymeric diphenylmethane diisocyanate. Three types of montmorillonite were used as clay component, i.e., montmorillonite modified by methyl tallow bis‐2‐hydroxyethyl ammonium (Cloisite®30B), a synthetic layered silicate (Laponite®RD), and an aluminium phyllosilicate absorbent, essentially impure clay consisting mostly of montmorillonite (Bentonite). Thermal properties of rigid polyurethane foams and nanocomposite foams were investigated by dynamical thermal analysis, thermogravimetry, oxygen index, and thermal conductivity measurements. It has been shown that the foams modified by selected nanofillers are characterized by high mechanical strength, as well as improved fire barrier properties. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2272–2281, 2013
Short range dispersal by a rare, obligate freshwater crustacean Triops cancriformis (Bosc)
Authors: Adams C.E. , Griffin L.R. , Benzies E. , Aherne D. , Bean C.W. , Dodd J. , Fairlamb D. , Maitland P.S.
Published: May 2013

Ephemeral freshwater ponds are highly discrete, limiting dispersal for obligate freshwater species and creating disjunct distributions.

The rare, freshwater, ephemeral pond dwelling, brachiopod crustacean, Triops cancriformis (Bosc) exhibits a highly disjunct spatial distribution across the UK.

This study examined 86 potentially suitable habitats for the resting cysts of this species on the north coast of the Solway estuary, south‐west Scotland, to address two hypotheses:

that there are populations of this species that, because of their unusual life history, remain undetected.

that this species is able to disperse over distances of several kilometres.

Incubation of sediment samples demonstrated the presence of T. cancriformis at two previously unknown sites. One further serendipitous discovery of adults at another site is also reported, bringing to eight the number of discrete ponds where this species has been recorded on the north Solway coast since 1907.

Only five natural populations are probably extant in the UK (with a sixth introduced population still extant). Four of these are on the Solway coast suggesting that this area is a conservation hotspot.

The inference from the spatial and temporal pattern of records of T. cancriformis from the Solway coast is that this species is able to disperse between discrete habitat patches over distances of at least several kilometres and successfully colonize new sites.

The mechanisms of this dispersal are unknown but transfer of material during floods or on the feet of deer, livestock, humans, waterfowl, or on farm machinery are all highly possible.

Copyright © 2013 John Wiley & Sons, Ltd.
Social Attention in a Virtual Public Speaking Task in Higher Functioning Children With Autism
Authors: Jarrold William , Mundy Peter , Gwaltney Mary , Bailenson Jeremy , Hatt Naomi , McIntyre Nancy , Kim Kwanguk , Solomon Marjorie , Novotny Stephanie , Swain Lindsay
Published: May 2013

Impairments in social attention play a major role in autism, but little is known about their role in development after preschool. In this study, a public speaking task was used to study social attention, its moderators, and its association with classroom learning in elementary and secondary students with higher functioning autism spectrum disorder (HFASD). Thirty‐seven students with HFASD and 54 age‐ and intelligence quotient (IQ)‐matched peers without symptoms of ASD were assessed in a virtual classroom public speaking paradigm. This paradigm assessed the ability to attend to nine avatar peers seated at a table, while simultaneously answering self‐referenced questions. Students with HFASD looked less frequently to avatar peers in the classroom while talking. However, social attention was moderated in the HFASD sample such that students with lower IQ, and/or more symptoms of social anxiety, and/or more attention deficit/hyperactivity disorder inattentive symptoms, displayed more atypical social attention. Group differences were more pronounced when the classroom contained social avatars versus nonsocial targets. Moreover, measures of social attention rather than nonsocial attention were significantly associated with parent report and objective measures of learning in the classroom. The data in this study support the hypothesis of the Social Attention Model of ASD that social attention disturbance remains part of the school‐aged phenotype of autism that is related to syndrome‐specific problems in social learning. More research of this kind would likely contribute to advances in the understanding of the development of the spectrum of autism and educational intervention approaches for affected school‐aged children. Autism Res 2013, ●●: ●●–●●. © 2013 International Society for Autism Research, Wiley Periodicals, Inc.
The chiral bioconversion and preclinical pharmacokinetic analysis of (R)‐(+)‐rabeprazole in beagle dogs by HPLC and HPLC‐MS/MS
Authors: Gao Yan‐hui , Xu Jia‐xing , Su Zhong‐xue , Song Li , Lou Hong‐xiang
Published: May 2013

In order to accurately investigate the preclinical pharmacokinetics of (R)‐(+)‐rabeprazole sodium injection, a reliable high‐performance liquid chromatography (HPLC) method was developed using a Chiral‐AGP column to prove that there is no chiral bioconversion of (R)‐(+)‐rabeprazole to (S)‐(−)‐rabeprazole in beagle dogs after single intravenous administration of (R)‐(+)‐rabeprazole sodium injection. An HPLC–tandem mass spectrometry (HPLC‐MS/MS) method for analysis of (R)‐(+)‐rabeprazole was developed and validated, and used to acquire the pharmacokinetic parameters in beagle dogs. (R)‐(+)‐Rabeprazole and internal standard omeprazole were extracted from plasma samples by protein precipitation and separated on a C18 column using methanol–5 mm ammonium acetate as mobile phase. Detection was performed using a turbo‐spray ionization source and mass spectrometric positive multi‐reaction monitoring mode. The linear relationship was achieved in the range from 2.5 to 5000 ng/mL. The method also afforded satisfactory results in terms of sensitivity, specificity, precision, accuracy and recovery as well as the stability of the analyte under various conditions, and was successfully applied to a preclinical pharmacokinetic study in beagle dogs after single intravenous administrations of (R)‐(+)‐rabeprazole sodium injection at 0.33, 2 and 6 mg/kg. Copyright © 2013 John Wiley & Sons, Ltd.
CO2 Capture and Desulfurization in Chemical Looping Combustion of Coal with a CaSO4 Oxygen Carrier
Authors: Zhang S. , Xiao R. , Yang Y. , Chen L.
Published: May 2013

Chemical looping combustion (CLC) of coal along with desulfurization was investigated in a fixed‐bed reactor with anhydrite as oxygen carrier and CaO and CaCO3 as desulfurizers, regarding the influence of temperature, pressure, mass ratio of coal to CaSO4, and Ca/S ratio. CO2 concentration and fuel conversion increased with higher temperature and pressure but decreased with higher mass ratios of coal to CaSO4. Approximately 94 % outlet CO2 concentration and 83 % carbon conversion could be achieved under optimum operating conditions. Desulfurization tests proved the higher desulfurization efficiencies of both CaO and CaCO3 at elevated temperatures and pressures. CaO performed better than CaCO3, and an optimum value of Ca/S ratio existed for CaO. These findings demonstrate a good performance of anhydrite as oxygen carrier and the promising prospects of desulfurization in CLC of coal.
Dialogues on cancer survivorship: A new model of international cooperation
Authors: Stein Kevin , Mattioli Vittorio
Published: May 2013

The authors describe the rationale and background of the present supplement to Cancer intended to stimulate a dialogue among researchers from Europe and North America regarding important issues faced by cancer survivors. Through jointly written articles addressing various aspects of cancer survivorship, each manuscript reports on the similarities, disparities, and problems viewed from the point of view of each author's respective continent. The supplement is meant to create a springboard for increased collaboration and aid in the development of a shared care model to improve the quality of cancer care, both during and after the completion of primary treatment. We hope that this effort may represent a new model of international cooperation, which is fruitful not only for the field of scientific research but also for identifying and sharing new approaches to the care and management of cancer survivorship issues, ultimately bringing improvements to quality of life of the growing population of cancer survivors. Cancer 2013;119(11 suppl):2083‐5. © 2013 American Cancer Society.
Cancer survivorship research in Europe and the United States: Where have we been, where are we going, and what can we learn from each other?
Authors: Rowland Julia H. , Kent Erin E. , Forsythe Laura P. , Loge Jon Håvard , Hjorth Lars , Glaser Adam , Mattioli Vittorio , Fosså Sophie D.
Published: May 2013

The growing number of cancer survivors worldwide has led to of the emergence of diverse survivorship movements in the United States and Europe. Understanding the evolution of cancer survivorship within the context of different political and health care systems is important for identifying the future steps that need to be taken and collaborations needed to promote research among and enhance the care of those living after cancer. The authors first review the history of survivorship internationally and important related events in both the United States and Europe. Lessons learned from survivorship research are then broadly discussed, followed by examination of the infrastructure needed to sustain and advance this work, including platforms for research, assessment tools, and vehicles for the dissemination of findings. Future perspectives concern the identification of collaborative opportunities for investigators in Europe and the United States to accelerate the pace of survivorship science going forward. Cancer 2013;119(11 suppl):2094‐108. © 2013 American Cancer Society.
Interventions to promote energy balance and cancer survivorship
Authors: Alfano Catherine M. , Molfino Alessio , Muscaritoli Maurizio
Published: May 2013

The growing population of cancer survivors worldwide and the growing epidemics of obesity and physical inactivity have brought increased attention to the role that interventions to promote exercise and a healthy body weight may play in mitigating the chronic and late effects of cancer. In this light, the authors describe the similarities and differences in research and clinical priorities related to energy balance interventions among post‐treatment cancer survivors in Europe versus North America. Randomized controlled trials that targeted nutrition, exercise, and weight are reviewed to determine the affect on survivorship outcomes. Interventions focused on improving prognosis or survival are investigated along with the emerging literature on the interventions targeting pathways and mechanisms of prognosis or survival. Current North American and European guidelines for diet, exercise, and weight control among cancer survivors also are investigated along with the implications of the current state of this science for clinical care. Finally, the authors delineate future European and American priorities for research and care involving energy balance among survivors. It is hoped that this dialogue launches an international conversation that will lead to better research and care for all post‐treatment cancer survivors. Cancer 2013;119(11 suppl):2143‐50. © 2013 American Cancer Society.
Employment challenges for cancer survivors
Authors: Mehnert Anja , de Boer Angela , Feuerstein Michael
Published: May 2013

There is a considerable body of evidence about the adverse effects of cancer and cancer treatments on employment, work ability, work performance, and work satisfaction among cancer survivors. There is also a growing consensus that cancer survivorship research needs to address the large variety of short‐term and long‐term work‐related problems and that programs to support return to work and employment should be developed and integrated into the follow‐up survivorship care of cancer patients. Cancer survivorship and employment can be considered from the perspective of the cancer survivor, the caregiver and the family, the employer and coworkers, the health care providers, and the community or society—elements that comprise many similarities but also differences between Europe and the Unites States and that may affect employment and return to work among cancer survivors in different ways. Previous research has specifically addressed the likelihood and timeliness of work return, including factors that promote and hinder return to work and work performance, and intervention studies and programs that focus on psychological, physical, pharmacologic, or multidisciplinary approaches to work. The area of work disability has emerged as an international field with research from areas throughout the globe. In this article, the authors provide an overview of the current state of scientific research in these areas and further provide a cancer survivorship and work model that integrates significant individual cancer‐related, treatment‐related, and work‐related factors and outcomes. The report concludes with a discussion of European and American contributions and possible future directions for the enhancement of current efforts. Cancer 2013;119(11 suppl):2151‐59. © 2013 American Cancer Society.
Space‐Time Resonances and the Null Condition for First‐Order Systems of Wave Equations
Authors: Pusateri Fabio , Shatah Jalal
Published: May 2013

In this manuscript we prove global existence and linear asymptotic behavior of small solutions to nonlinear wave equations. We assume that the quadratic part of the nonlinearity satisfies a nonresonance condition that is a generalization of the null condition given by Klainerman. © 2013 Wiley Periodicals, Inc.
Synthesis of Cell‐Penetrating S‐Galactosyl–Oligoarginine Peptides as Inducers of Recombinant Protein Expression under the Control of lac Operator/Repressor Systems
Authors: Mizuta Yukina , Takasu Akinori , Higuchi Masahiro
Published: May 2013

The synthesis of glycodendrimers and glycopoly(oxazoline)s as inducers of recombinant protein expression has recently been reported; however, these compounds induced the expression of only small amounts of the green fluorescence protein (GFP), which was used as the model recombinant protein, because of their poor ability to penetrate the Escherichia coli cell membrane. Therefore, S‐galactosyl–oligo(Arg) conjugates have now been synthesized to overcome this problem. Following in vivo expression of GFP induced by each of the S‐galactosyl (Arg)n constructs (n=5, 6, 8) at the T5 promoter in E. coli for 18 hours, we visually observed that the cultures fluoresced green light when excited with UV light. The fluorescent intensities for these cultures were greater than that found for a control culture, which indicates that the peptides had induced GFP expression. Quantitative fluorescent measurements also supported the observations that the peptides were better inducers of GFP expression than the galactosyl dendrimers and the poly(oxazoline)s and the natural inducer lactose. Because the level of GFP expression was directly related to the number of arginine moieties in each peptide, we propose that the number of arginine moieties is responsible for how well each peptide passes through the E. coli membrane, which affects the expression level. A similar tendency was observed when the T7 promoter was placed upstream from the gene for an artificial extracellular matrix protein and the S‐Gal–oligo(Arg) peptides were used as inducers. To assess how the distance between two galactosyl moieties as well as how the multivalent effect (cluster effect) in an oligo(Arg) inducer affects the expression level of GFP, we synthesized a conjugate of Lys(Arg)8 (Lys=lysine) and two S‐galactosyls, which enhanced the expression of GFP in comparison with that obtained for S‐Gal(Arg)8.
A Clinical Treatment Intervention for Dysphoria: Externalizing Metaphors Therapy
Authors: McGuinty Everett , Armstrong David , Carrière Anne‐Marie
Published: May 2013

The purpose of this article is to explore a novel, short‐term treatment intervention for internalizing behaviours. This intervention is primarily based upon an externalizing process, transforming of metaphoric imagery, and shifting of underlying maladaptive emotional schemas. This article addresses the clinical population of children and youth, specifically through outlining the protocol, externalizing metaphors therapy. A selective review of significant works regarding the efficacy of short‐term therapy was conducted, including the process of change within narrative therapy. It is proposed that two specific processes account for the mental health change experienced by clients who receive this new treatment intervention: (1) externalization of problems and (2) purposeful client‐generated metaphor manipulation, impacting upon underlying schemas. From these theoretical constructs, the present article outlines a three‐session treatment protocol that manualizes these key clinical processes. A case study is presented to illustrate this intervention for anxiety and depression. Further clinical research is underway to address the testable hypotheses resulting from the current theoretical model. Clinical trials in brief psychotherapy are suggested to empirically evaluate the efficacy of this new treatment intervention for dysphoria. Copyright © 2013 John Wiley & Sons, Ltd.

KEY PRACTITIONER MESSAGE

This article outlines a short‐term treatment intervention for anxiety and depression (dysphoira) through a novel 3‐session model, where the clinician‐practitioner can obtain competency through a one‐day workshop.

Its relevance for the clinical researcher and the mental health community is in its versatility in addressing internalizing behavior for four clinical populations: (1) children and adolescents; (2) children and adolescents on the autism spectrum; (3) adults in general; and, (4) adults with a dual‐diagnosis.

The treatment protocol described within is based upon the externalizing and deconstructive properties of Narrative Therapy, and the transformation of metaphoric imagery of Metaphor Therapy; both of which have little empirical support with narrative practices gaining international attention and widespread usage ‐ through brief therapy, long‐term therapy, and walk‐in clinics in North America.

For the first time, the theoretical constructs of the 3‐session model are described and a case example illustrates the interlinking concepts.