bluuebunny/crossref_metadata_2025 huggingface dataset:
Coronary Flow Velocity Reserve is Improved by PPAR‐α Agonist Fenofibrate in Patients with Hypertriglyceridemia
Authors: Wang Guang , He Liyun , Liu Jinbo , Yu Jie , Feng Xinheng , Li Fuwang , Hao Yanting , Mao Jieming , Hong Tianpei , Chen Alex F. , Wang Xian
Published: January 2012

Summary  Introduction: Fenofibrate, an agonist of peroxisome proliferator‐activated receptor‐α (PPAR‐α), has a vascular protective effect. Aims: We investigated the effect of the PPAR‐α agonist on coronary artery endothelial function in patients with hypertriglyceridemia. Methods: Fifty‐eight patients with hypertriglyceridemia were divided into two groups: control (no treatment; n = 23) and fenofibrate treatment (n = 35), 200 mg/d, for 6 months. The patients had undergone rest and adenosine treatment to induce hyperemia for quantification of coronary flow velocity reserve (CFVR) by noninvasive Doppler echocardiography before treatment and at 6‐month follow‐up. Pulse wave velocity (PWV) was measured before treatment and at 6‐month follow‐up. Results: CFVR was significantly improved with fenofibrate treatment as compared with baseline level and control group (3.14 ± 0.36 vs. 2.80 ± 0.58 and 2.79 ± 0.65, P < 0.01 and 0.05, respectively), with no difference between baseline levels and untreated controls. In addition, at 6 months, plasma level of homocysteine was significantly increased with fenofibrate treatment as compared with at baseline and control group (median 18.13 [range 14.46–22.02]μmol/L vs. 14.09 [12.01–18.81] and 13.34 [9.69–17.06]μmol/L, P < 0.001 and 0.01, respectively). Furthermore, at 6 months, PWV was significantly decreased with fenofibrate treatment as compared with control group (1446 ± 136 cm/s vs. 1570 ± 203 cm/s, P < 0.05). Conclusions: Treatment with PPAR‐α agonist fenofibrate significantly improved CFVR and arterial stiffness in patients with hypertriglyceridemia. This endothelial protective effect may be reduced in part by the side effect of increasing homocysteine.
Application of Ostrom’s Principles for Sustainable Governance of Common‐Pool Resources to Near‐Earth Orbit
Authors: Johnson‐Freese Joan , Weeden Brian
Published: January 2012

Near‐Earth orbit is a key global resource, hosting assets critical to governments, militaries and commercial entities and providing services for global communications, remote sensing, national and international security, and accurate positioning and timing. It is also an increasingly crowded, congested and contested environment, at risk from both intentional and unintentional activities and events, and threats natural and human‐made. Ensuring the long‐term sustainability of the space environment is an increasingly recognized need by all users of space. This article considers the viability of principles regarding sustainable common‐pool resources (CPRs) established by Elinor Ostrom for space governance. In this initial consideration, we focus specifically on the issues of boundaries, collective choice arrangements and monitoring. Within those contexts, Ostrom’s principles appear most useful for identifying gaps in the current space governance system and mechanisms. Further, while Ostrom provides multiple success stories for her model, they typically include common‐pool regimes functioning at a local level, with success stories on a larger scale elusive. Near‐Earth orbit is perhaps the largest‐scale CPR to consider. Consequently, not only is additional work needed to relate Ostrom’s model specifically to space, but to determine the limits of applicability of Ostrom’s model and other models that should be considered.

Policy Implications

 The global commons of outer space, particularly the region where satellites orbit around the Earth, faces a collective action problem of how to ensure the long‐term sustainability of space activities.

 The current governance mechanisms for outer space activities were largely developed during the cold war, and are not sufficient to deal with the collective action problems stemming from the growing number of space actors and users.

 Space actors exist with varying levels of capabilities, which complicates defining resource appropriator rights and responsibilities.

 Common agreement is needed among space actors on the bounds of the space domain to allow resource appropriators to set the governance limitations, who has the right to make use of it and what governance regime applies.

 Existing institutions for debating, creating and modifying space governance regimes fall short of the requirement that most actors affected by the rules can participate in their creation.

 Space situational awareness will play a crucial role in monitoring the status of the space commons, adherence to rules and norms, and creating transparency and confidence among space actors.
The Political Economy of Ecology: Prospects for Transforming the World Economy at Rio Plus 20
Authors: Haas Peter M.
Published: January 2012

This article assesses the prospects for advancing to a green economy at Rio Plus 20 through the perspective of international political economy writings on economic transformations and regime governance. In order to achieve robust investment in revolutionary new technologies a clear international political project is required that provides a common purpose, clear regulatory and legal rules, and formal organisational efforts for resource mobilisation, compensation of losers, and enforcement. It concludes with an appraisal of efforts underway to create the political foundation for a green economy, suggesting the creation of a new international organization for green technology innovation, and assigning the United Nations Environment Programme (UNEP) to environmental science assessment.
Global Commons Revisited
Authors: Vogler John
Published: January 2012

Global commons are areas and resources defined as being beyond sovereign jurisdiction. They are socially constructed and this article identifies four: the high seas and deep seabed, Antarctica, outer space and the global atmosphere although attempts to designate new areas as commons are also noted. The construction of global commons, it is argued, has been determined by shifts in human knowledge, capability and perceptions of scarcity. The commons problem, as defined by Hardin and other analysts arises from the ecological consequences of open access, but also from the renewed concerns of strategists about the military use of common spaces. In the international system a primary response has been to extend sovereignty and the degree to which the global commons have been enclosed is assessed. An alternative model is provided by the negotiation of common heritage status, but since the experiment with the deep sea bed this has not found favour in the Arctic, Antarctic and elsewhere. In terms of the continuing management of the commons the international community has resorted to an array of regulatory regimes of varying coverage and effectiveness
Introduction ‐ The Governance of the Global Commons: Much Unfinished Business?
Authors: Dodds Klaus
Published: January 2012

The planting of a Russian flag at the bottom of the central Arctic Ocean in the summer of 2007 drew attention, in dramatic fashion, to a subterranean space beyond national jurisdiction. While the region was a permanent feature in Cold War strategic planning, the flag planting incident was rapidly framed as indicative of a different kind of struggle –‘a scramble for territory and resources’. Notwithstanding the media led hyperbole, one question to emerge was an apparently straightforward one – did any one state or group of states possess sovereign rights in the central Arctic Ocean? More generally, how do issues of access, control, property rights and resource use continue to affect the governance of the global commons? This special section explores those questions.
The Cu isotopic composition of iron meteorites
Authors: BISHOP Matthew Cole , MOYNIER Frederic , WEINSTEIN Charlotte , FRABOULET Jean‐Gabriel , WANG Kun , FORIEL Julien
Published: January 2012

Abstract– High‐precision Cu isotopic compositions have been measured for the metal phase of 29 iron meteorites from various groups and for four terrestrial standards. The data are reported as the δ65Cu permil deviation of the 65Cu/63Cu ratio relative to the NIST SRM 976 standard. Terrestrial mantle rocks have a very narrow range of variations and scatter around zero. In contrast, iron meteorites show δ65Cu approximately 2.3‰ variations. Different groups of iron meteorites have distinct δ65Cu values. Nonmagmatic IAB‐IIICD iron meteorites have similar δ65Cu (0.03 ± 0.08 and 0.12 ± 0.10, respectively), close to terrestrial values (approximately 0). The other group of nonmagmatic irons, IIE, is isotopically distinct (−0.69 ± 0.15). IVB is the iron meteorite group with the strongest elemental depletion in Cu and samples in this group are enriched in the lighter isotope (δ65Cu down to −2.26‰). Evaporation should have produced an enrichment in 65Cu over 63Cu (δ65Cu >0) and can therefore be ruled out as a mechanism for volatile loss in IVB meteorites. In silicate‐bearing iron meteorites, Δ17O correlates with δ65Cu. This correlation between nonmass‐dependent and mass‐dependent parameters suggests that the Cu isotopic composition of iron meteorites has not been modified by planetary differentiation to a large extent. Therefore, Cu isotopic ratios can be used to confirm genetic links. Cu isotopes thus confirm genetic relationships between groups of iron meteorites (e.g., IAB and IIICD; IIIE and IIIAB); and between iron meteorites and chondrites (e.g., IIE and H chondrites). Several genetic connections between iron meteorites groups are confirmed by Cu isotopes, (e.g., IAB and IIICD; IIIE and IIIAB); and between iron meteorites and chondrites (e.g., IIE and H chondrites).
Petrographic constraints on the diversity of chondrule reservoirs in the protoplanetary disk
Authors: JONES Rhian H.
Published: January 2012

Abstract– Chondrules from different chondrite groups show characteristic properties, including abundances of different chondrule textural types, chondrule sizes, oxygen isotope compositions, chondrule bulk compositions, and petrographic properties of type I and type II chondrules, including abundances of relict grains. Overall, it can be argued that each chondrite group sampled a unique chondrule reservoir, and that chondrite groups may represent fractions of larger reservoirs that are represented by chondrite classes. These observations provide constraints for models of the early solar system, in which it is necessary to establish multiple separate chondrule reservoirs and maintain them over extended time periods. Models for accretion of chondrite parent bodies must be able to account for localized accretion of chondrules that were formed in spatially or temporally separated reservoirs.
Iron deficiency in pyrrhotite of suevites from the Chesapeake Bay impact crater, USA—A consequence of shock metamorphism?
Authors: MANG Christoph , KONTNY Agnes , HARRIES Dennis , LANGENHORST Falko , HECHT Lutz
Published: January 2012

Abstract– Pyrrhotite from suevite of the 35 Ma Chesapeake Bay impact structure (CBIS) shows a shock metamorphism and we report on several mineralogical and magnetic features. Pyrrhotite shows strong brittle deformation with a high density of stacking faults, twinning parallel to the hexagonal (001) planes and average fault distances in the order of 10 nm. Although the determination of a superstructure was not possible due to the lattice defects, the reflections of the NiAs subcell, which is typical of all pyrrhotite modifications, were clearly detected. This phase is ferrimagnetic with a Curie temperature (TC) between 350 and 365 °C, and suevite with this phase does not show the 34 K transition. The most peculiar feature is the low metal/sulfur ratio of 0.81, which indicates a distinctly higher vacancy concentration than for 4C pyrrhotite and a composition close to smythite (Fe9S11). This phase carries a stable natural remanent magnetization and is relatively hard magnetic. Steep inclinations of the natural remanent magnetization vector, however, suggest that this phase has been remagnetized by the drilling process. A possible explanation is the magnetic domain size of faultless areas of about 10 nm in diameter, which is at the lower limit of the single domain size near the threshold, below which superparamagnetic behavior occurs. The low thermal stability of this phase excludes postshock heating above 300 °C for the suevite of the CBIS. Our results imply that the iron‐deficient pyrrhotite is produced by shock metamorphism, although an iron loss due to shock has never been reported before for pyrrhotite.
Controlling the receptor for advanced glycation end‐products to conquer diabetic vascular complications
Authors: Yamamoto Yasuhiko , Yamamoto Hiroshi
Published: January 2012

Diabetic vascular complications, such as cardiovascular disease, stroke and microangiopathy, lead to high rates of morbidity and mortality in patients with long‐term diabetes. Extensive intracellular and extracellular formation of advanced glycation end‐products (AGE) is considered a causative factor in vascular injuries in diabetes. Receptor‐dependent mechanisms are involved in AGE‐induced cellular dysfunction and tissue damage. The receptor for AGE (RAGE), originally an AGE‐binding receptor, is now recognized as a member of pattern‐recognition receptors and a pro‐inflammatory molecular device that mediates danger signals to the body. Previous animal studies have shown RAGE dependent of diabetic vascular injuries. Prophylactic and therapeutic strategies focusing on RAGE and its ligand axis will be of great importance in conquering diabetic vascular complications. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2011.00191.x, 2012)
Performance of a Direct Injection Diesel Engine Fueled by a Heavy Oil With the Addition of Low Density Polyethylene (LDPE) Polymer
Authors: Soloiu V. , Covington A.
Published: January 2012

Considering the escalating cost of fossil fuels in correlation with the growing influence of sustainability, the need to seek new alternative fuels is increasing rapidly. This movement has lead researchers to look beyond the usual alternative fuels and focus on plastics as an energy resource in the form of a low density polyethylene (LDPE) used throughout the global community. The authors investigated the injection and combustion of a new class of polymer fuel containing 5% LDPE by weight in a heavy fuel oil (AHFO) in a direct injection diesel engine, in order to evaluate its effectiveness for application as a new alternative fuel. The analysis occurred at 1200 rpm, under loads that ranged from BMEP 1.4-6.04 bar. In order to maintain the fuel’s viscosity around 20 cSt the fuel was heated at 130-150 °C. The smoke (bosch) and emission analysis were also performed and provided promising results in terms of engine performance. This suggests that the feedstock of LDPE may be a viable substitute for AHFO for application in a diesel engine with the addressing of the technical challenges associated with the injection system operation.
Rotordynamic Force Coefficients for Three Types of Annular Gas Seals With Inlet Preswirl and High Differential Pressure Ratio
Authors: Ertas B. H. , Delgado A. , Vannini G.
Published: January 2012

The following paper presents and compares rotordynamic force coefficients for three types of non-contact annular gas seals, which include a labyrinth (LABY), honeycomb (HC), and a fully partitioned damper seal (FPDS). These three annular seals represent the typical seal types used in process gas centrifugal compressors at the balance piston location or center seal location to limit internal leakage and ensure a robust rotordynamic design. Tests were conducted on 170.6 mm (6.716 in) diameter seals for rotor speeds up to 15 kprm, inlet air pressure of 6.9 bar (100 psi), ambient back pressure, and with inlet gas preswirl. The three seals were designed to have the same nominal clearance and similar axial lengths. Testing was conducted on a controlled motion test rig possessing non-synchronous excitation capability up to 250 Hz. Three different test methods were employed to give confidence in the rotordynamic coefficients, which include static force deflection tests, mechanical impedance tests, and dynamic cavity pressure tests. Results from experiments compare force coefficients for all seal configurations while paying special attention to the crossover frequencies of the effective damping term. All seals possessed negative effective damping at lower excitation frequencies with inlet preswirl, where the straight-through FPDS possessed the lowest cross over frequency of 40 Hz at 15 krpm. The testing also revealed that the preswirl parameter had significantly more influence on effective damping levels and crossover frequencies when compared to rotor speed.
Air System and Diesel Combustion Modeling for Hardware in the Loop Applications
Authors: Millet Jean-Baptiste , Maroteaux Fadila , Aubertin Fabrice
Published: January 2012

The development of engine control unit (ECU) systems for series production requires an important validation phase. In order to reduce the number of time consuming and expensive vehicle tests, the ECU is validated using hardware in the loop (HIL) test bench. The HIL simulates the engine behavior in real-time simulations to generate consistent sensor values for all engine operating points, e.g., starting phase, transient behavior, static behavior, etc. Mean value engine models (MVEM) are able to run in real time and are appropriate for HIL test systems. In this paper we present a full MVEM taking into account all engine components: air system (air filter, turbocharger, charge air cooler, throttle valve, intake and exhaust manifolds, EGR valve, and turbine), oxidation catalyst (OxiCat), and diesel particulate filter (DPF). Additionally, combustion models have been developed to simulate the influence of the injection strategies (pre, main, post, and late injections) on the exhaust temperature and the unburned hydrocarbon emission (HC). These are taken into consideration in the exothermal reactions models inside OxiCat and DPF. The results show that the model prediction in term of pressure and temperature are in good agreement with the original equipment manufacturer (OEM) project data. The after treatment temperature evolutions in the OxiCat and DPF are well reproduced by the proposed model.
Unique Processing During a Period of High Excitation/Inhibition Balance in Adult-Born Neurons
Authors: Marín-Burgin Antonia , Mongiat Lucas A. , Pardi M. Belén , Schinder Alejandro F.
Published: January 2012

Neurogenesis and Pattern Integration

The adult hippocampus continuously produces new neurons that integrate into the dentate gyrus network and contribute to information processing. What features of adult-born neurons are important for information processing in the dentate gyrus?

Marín-Burgin
et al.

(p.
1238
, published online 26 January; see the Perspective by

Kempermann

) labeled newborn neurons and used sophisticated electrophysiological and imaging techniques to show that immature neurons integrated a broader variety of synaptic inputs from different origins compared with mature neurons, which were highly input specific. Thus, immature neurons may represent a population of integrators that are broadly tuned during a transient period and may encode most features of incoming information. After maturation, new granule cells display a high activation threshold and input specificity to become good pattern separators.
A systematic review and thematic analysis of cinema in medical education
Authors: Darbyshire Daniel , Baker Paul
Published: January 2012

The use of cinema in medical education has the potential to teach students about a variety of subjects, for instance by illustrating a lecture on communication skills with a clip of Sir Lancelot Spratt (Doctor In The House, 1954) demonstrating a paternalistic, doctor-centred approach to medicine or nurturing an ethical discussion around palliative care and dying using the cinematic adaptation of American playwright Margaret Edson'sWit(2001). Much has been written about this teaching method across several medical academic disciplines. It is the aim of this review to assimilate the various experiences in order to gain an insight into current expertise. The results are presented by the following headings under which the articles were examined: the source journal, year of publication, article type, theme, content, target, authors, if a clip or the entire film was used, and if any feedback was documented. This is followed by a chronological account of the development of the literature. Such an approach will allow the reader to gather specific information and contextualise it. This review does not critically appraise the quality of the evidence nor does it determine its validity, rather it is hoped that having read the review educators will know where to locate previous accounts of work that will help them develop more engaging pedagogy.
Sexual dysfunction in men with type 2 diabetes
Authors: Isidro Maria Luisa
Published: January 2012

Sexual dysfunction (SD) is common in type 2 diabetic men, but few subjects are diagnosed and treated. The prevalence of diabetes mellitus is increasing worldwide. It is expected that the number of subjects suffering from SD increases in the near future. Most studies of SD in diabetic men have focused on erectile dysfunction. There is a dearth of studies in the area of the other forms of SD. SD has consequences on the psychological well-being and reproductive function. They can be the first symptom of comorbidities or a treatment side effect. Erectile dysfunction is increasingly being recognised as an early marker of organic incipient systemic disease. Evaluation for any SD includes a complete medical history, detailed sexual history, physical examination, psychosocial assessment and, sometimes, complementary studies. Initial treatment of any SD should eliminate any modifiable factor that may lead to or aggravate the dysfunction. Phosphodiesterase type 5 inhibitors are the preferred therapy for most men with organic erectile dysfunction who do not have a specific contraindication to their use. Pharmacological treatment of premature ejaculation includes on-demand or daily dosing of certain selective serotonin reuptake inhibitors or clomipramine and on-demand topical local anaesthetics. Delayed ejaculation and anejaculation due to vascular or neuropathic damage are usually irreversible. The issue of infertility in patients with anejaculation or retrograde ejaculation seeking to have children should be addressed. No study specifically conducted in diabetic men on the treatment of hypoactive sexual desire disorder, apart from that occurring in the context of hypogonadism, has been published.
Medical error disclosure: the gap between attitude and practice
Authors: Ghalandarpoorattar Seyedeh Mojgan , Kaviani Ahmad , Asghari Fariba
Published: January 2012

Background

This study aims to evaluate the attending surgeons' and residents' attitudes towards error disclosure and factors that can potentially affect these tendencies in major academic hospitals affiliated with Tehran University of Medical Sciences (TUMS).

Methods and material

In a cross-sectional study, self-administered questionnaires were delivered to all attending surgeons and second to fourth year surgical residents of TUMS during October and November 2009. The questionnaire contained two clinical scenarios and questions regarding physicians' attitudes towards disclosing medical error and their actual practice in the case of their last error. Of the 63 distributed questionnaires, 53 (84.1%) were completed and returned.

Results

Participants were less likely to disclose minor (39.6%; 21/53) than major (49.1%; 29/53) medical errors. Participants believed that their most important concerns for not disclosing errors were fear of a malpractice lawsuit (71.7%, n=38), losing patients' trust (62.3%, n=33), and emotional reactions of the patients and their relatives (56.6%, n=30). Although most physicians indicated they would disclose errors in minor and major scenarios, only 16.7% (n=8) had disclosed their last medical errors to their patients, two of which had resulted in patients taking legal action.

Conclusion

There was an obvious gap between surgeons' intentions and actual practices concerning disclosure of medical error. Education in medical error management to professionally support error disclosure might help reduce the gap.
Diagnosis and management of patent foramen ovale
Authors: Buchholz Stefan , Shakil Ayesha , Figtree Gemma A , Hansen Peter S , Bhindi Ravinay
Published: January 2012

The foramen ovale is a slit-like anatomical structure located in the interatrial wall of the fetal heart that enables right-to-left shunting during fetal development. Although this hole generally closes completely shortly after birth due to shifting pressures in the atrial chambers, it remains open, or ‘patent’, in about 25% of cases representing a potential substrate for right-to-left shunting during adult life. A patent foramen ovale (PFO) is usually haemodynamically insignificant, even when large, but is the most common cause of right-to-left shunt. Large-diameter PFOs may act as a pathway for passage of thrombus, air, fat, vegetation or vasoactive substances from the venous to the arterial circulation, potentially causing paradoxical emboli and stroke, inappropriate decompression sickness in divers, platypnoea-orthodeoxia syndrome and aural migraine. Over the past two decades, the association between PFO and the occurrence of migraine and cryptogenic stroke, particularly in younger adults, has been subject to considerable controversy and debate. Currently, semi-invasive contrast-transoesophageal echocardiography is accepted as the gold standard to detect right-to-left shunt across a PFO, but other imaging modalities utilising contrast such as second-harmonic transthoracic echocardiogram, transcranial Doppler sonography, CT and cardiac MRI have been shown to have similar sensitivity and specificity in detecting a PFO when compared with transoesophageal echocardiography. In this review the authors discuss embryological origins, diagnostic measures and evidence-based treatment options for the prevention of PFO-related paradoxical embolism, with emphasis on cryptogenic stroke and migraine.
FUSING EMG AND VISUAL DATA FOR HANDS-FREE CONTROL OF AN INTELLIGENT WHEELCHAIR
Authors: WEI LAI , HU HUOSHENG , ZHANG YI
Published: January 2012

This paper presents a novel hands-free human machine interface (HMI) for elderly and disabled people by fusing multi-modality bioinformation abstracted from forehead electromyography (EMG) signals and facial images of a user. The interface allows users to drive an electric-powered wheelchair using face movements such as jaw clenching and eye blinking. An indoor environment is set up for evaluating the application of this interface. Five intact subjects participated in the experiment to drive the intelligent wheelchair following designated routes and avoiding obstacles. Comparisons are made between this new interface and the traditional joystick control in terms of the easiness of control, travel time, wheelchair trajectory, and error command. The experimental results show that the proposed new control method is comparable to the joystick control method and can be used as a hands-free controller for the intelligent wheelchair.
MANIPULATION OF A MOBILE MODULAR MANIPULATOR INTERACTING WITH THE ENVIRONMENT WITH THE ASSISTANCE OF TACTILE SENSING FEEDBACK
Authors: WANG JINGGUO , LI YANGMIN
Published: January 2012

Since tactile sensing feedback can provide very useful and crucial information to the problems of contact, it can be widely applied in the control of the mobile manipulator in case of contacting with the complex or unknown environments. This paper presents a control method for a mobile modular manipulator (MMM) interacting with the environment, in which the feedback does not only include the force-sensing feedback but also the tactile sensing feedback. In order to detect the feedback information from the environment, a kind of tactile sensor is mounted at the tip of the end-effector of the MMM. The dynamic equations of the whole system are formulated and the hybrid control method is designed after several tactile sensing-assisted strategies are considered. A mobile manipulator is built up to make real experiments and the results validate the proposed methods.
C*-SIMPLE GROUPS: AMALGAMATED FREE PRODUCTS, HNN EXTENSIONS, AND FUNDAMENTAL GROUPS OF 3-MANIFOLDS
Authors: DE LA HARPE PIERRE , PRÉAUX JEAN-PHILIPPE
Published: January 2012

We establish sufficient conditions for the C*-simplicity of two classes of groups. The first class is that of groups acting on trees, such as amalgamated free products, HNN-extensions, and their nontrivial subnormal subgroups; for example normal subgroups of Baumslag–Solitar groups. The second class is that of fundamental groups of compact 3-manifolds, related to the first class by their Kneser–Milnor and JSJ decompositions.

Much of our analysis deals with conditions on an action of a group Γ on a tree T which imply the following three properties: abundance of hyperbolic elements, better called strong hyperbolicity, minimality, both on the tree T and on its boundary ∂T, and faithfulness in a strong sense. An important step in this analysis is to identify automorphisms of T which are slender, namely such that their fixed-point sets in ∂T are nowhere dense for the shadow topology.
Band-Structure Lineup at In0.2Ga0.8N/Si Heterostructures by X-ray Photoelectron Spectroscopy
Authors: Kumar Mahesh , Roul Basanta , Bhat Thirumaleshwara N. , Rajpalke Mohana K. , Kalghatgi A. T. , Krupanidhi S. B.
Published: January 2012

In0.2Ga0.8N layers were directly grown on Si(111) substrate by plasma-assisted molecular beam epitaxy (PAMBE). Structural characteristics of the as-grown InGaN epilayers were evaluated high resolution X-ray diffraction and composition of InGaN was estimated from photoluminescence spectra using the standard Vegard's law. High-resolution X-ray photoemission spectroscopy measurements were used to determine the band offset of wurtzite-In0.2Ga0.8N/Si(111) heterojunctions. The valence band of InGaN is found to be 2.08±0.04 eV below that of Si. The conduction band offset (CBO) of InGaN/Si heterojunction is found ∼0.74 eV and a type-II heterojunction.
Variation of Chemical Vapor Deposited SiO2 Density Due to Generation and Shrinkage of Open Space During Thermal Annealing
Authors: Sometani Mitsuru , Hasunuma Ryu , Ogino Masaaki , Kuribayashi Hitoshi , Sugahara Yoshiyuki , Uedono Akira , Yamabe Kikuo
Published: January 2012

Chemical vapor deposited (CVD) SiO2 using tetraethoxysilane has a low density compared with thermally grown SiO2, and the as-deposited film contains impurities. In addition, compressive stress exists in the Si–O–Si network. In this work, CVD SiO2 films annealed with various thermal budgets were evaluated using ellipsometry. Positron annihilation spectroscopy indicated that the desorption of residual impurities by thermal annealing generates open spaces in the films. Subsequent annealing shrinks the open spaces and relaxes the compressive stress with reconstruction of the Si–O–Si network. Consequently, the refractive index of CVD SiO2 shows turn-around characteristics with increasing annealing temperature.
Resolution-Enhanced Magnification of a Far Three-Dimensional Object Image by Using the Moving-Direct-Pixel-Mapping Method in Scalable Integral-Imaging System
Authors: Piao Yongri , Zhang Miao , Kim Eun-Soo
Published: January 2012

In this paper, we propose an effective approach for resolution-enhanced magnification of a far three-dimensional (3D) object image by employing the moving-direct-pixel-mapping (MDPM) method in the scalable integral imaging system. In the proposed method, a set of elemental image arrays (EIAs) are picked up from a far 3D object with the moving-array-lenslet technique (MALT) and computationally transformed into a new set of EIAs by using the MDPM method, which looks like the EIAs virtually picked up from a close object. These newly transformed EIAs then are interlaced together to form an enlarged EIA, from which resolution-enhanced magnification of a far 3D object image can be achieved. Good experimental results confirm the feasibility of the proposed method.
Efficiency and Thermal Stability Enhancements of Sr2SiO4:Eu2+ Phosphor via Bi3+ Codoping for Solid-State White Lighting
Authors: Park Seung Hyok , Yoon Ho Shin , Boo Hye Min , Jang Ho Gyeom , Lee Kyoung Hwa , Im Won Bin
Published: January 2012

Bi and Eu-codoped yellow-emitting phosphors of composition Sr1.95-x
Eu0.05Bi
x
SiO4 were prepared, and their emission and thermal quenching characteristics were investigated. The initial PL intensity and thermal quenching behaviors of Sr1.95-x
Eu0.05Bi
x
SiO4 were affected by the Bi-codoping as a coactivator. When 0.01 mol % of Bi was codoped to Sr1.95-x
Eu0.05Bi
x
SiO4, it showed an intense emission peak at 543 nm under 450 nm excitation. The peak intensity corresponds to a relative intensity of 112% of a commercial Sr2SiO4:Eu2+ phosphor (Force4 Corp.), which may be attributed to energy transfer between Bi3+ and Eu2+. The results suggest that phosphors deriving from Sr1.95-x
Eu0.05Bi
x
SiO4 will be a breakthrough for white light emitting diode (LEDs) and related applications in terms of efficiency enhancement and thermal stability.
Optical Characteristic Improvement of Neodymium-Doped Lanthanum Fluoride Thin Films Grown by Pulsed Laser Deposition for Vacuum Ultraviolet Application
Authors: Ieda Mirai , Ishimaru Tatsuya , Ono Shingo , Yamanoi Kohei , Cadatal-Raduban Marilou , Shimizu Toshihiko , Sarukura Nobuhiko , Fukuda Kentaro , Suyama Toshihisa , Yokota Yuui , Yanagida Takayuki , Yoshikawa Akira
Published: January 2012

Neodymium-doped lanthanum fluoride (Nd3+:LaF3) thin films were successfully grown on MgF2(001) substrates by pulsed laser deposition. Photoluminescence spectra revealed a dominant peak at 173 nm with a decay time of 7.8 ns, which is similar to the results obtained from a bulk Nd3+:LaF3 crystal. Improvements in crystalline quality and vacuum ultraviolet (VUV) luminescence quantum efficiency were achieved by substrate heating, with optimum results being obtained at 400 °C. These results would open up possibilities in the development of a light-emitting device operating in the VUV region.
A Subthreshold Current Model of Fully-Depleted Silicon-on-Insulator Metal–Oxide–Semiconductor Field Effect Transistors with Vertical Gaussian Profile
Authors: Zhang Guohe , Chen Kebin , Liang Feng
Published: January 2012

A subthreshold current of fully-depleted (FD) silicon-on-insulator (SOI) metal–oxide–semiconductor field effect transistors (MOSFETs) with vertical Gaussian profile is presented in the paper. The model is based on analytical approximated solution of two-dimensional Poissons' equation and Boltzmann transport equation. The front and the back channel currents are effectively derived using a novel inversion layer model and the boundary conditions which take the nonuniform doping into account. The results are matched well with the numerical simulation results obtained by Sentaurus Technology Computer-Aided Design (TCAD). The model is believed to provide a deep physical insight and understanding of FD-SOI MOSFETs with a non-uniform doping profile operating in the subthreshold regime.
Device Simulation of Ditch and Elevated Electrode Structures in Organic Thin-Film Transistors
Authors: Shim Chang-Hoon , Sekiya Takashi , Hattori Reiji
Published: January 2012

A novel organic thin-film transistor structures named the “ditch structure” or “elevated electrode structure” is proposed. Device simulations show that the electrical properties of this structure are almost the same as those of a staggered structure (top-contact structure). These results are explained in terms of the electric field concentration at source electrodes with sharp corners and the electric field being vertical to the direction of the gate. The manufacturing process of this structure is as simple as that of a planar structure (bottom-contact structure), and the performance is as high as that of a staggered structure.
Enhanced Growth of Diamond Grains in Ultrananocrystalline Diamond/Hydrogenated Amorphous Carbon Composite Films by Pulsed Laser Deposition with Boron-Blended Graphite Targets
Authors: Ohmagari Shinya , Katamune Yūki , Ichinose Hikaru , Yoshitake Tsuyoshi
Published: January 2012

Ultrananocrystalline diamond (UNCD)/hydrogenated amorphous carbon composite films were prepared by pulsed laser deposition with boron-blended graphite targets and the effects of the boron-doping on the growth of UNCD grains were investigated. With an increase in the boron content, the grain size was increased from 5 to 23 nm accompanied by the lattice constant approaching that of bulk diamond. The sp3/(sp3+ sp2) ratio estimated from the X-ray photoemission spectra was enhanced by the boron-doping, which might be predominantly attributable to the enlarged grains. The near-edge X-ray absorption fine-structure spectroscopic measurement revealed that boron atoms are preferentially distributed into grain boundaries. On the basis of the results, the roles of the boron atoms in the enhanced crystalline growth are discussed. We consider that the crystalline growth posterior to the nucleation is facilitated by boron atoms neighboring UNCD grains or by boron-containing energetic species in plasma.
Reduction of In Composition in Heavily Zn-Doped InAlGaAs Layers Grown at Low Temperature by Metalorganic Chemical Vapor Deposition
Authors: Yokoyama Haruki , Hoshi Takuya , Shigekawa Naoteru , Ida Minoru
Published: January 2012

Growth of heavily Zn-doped InAlGaAs at low temperature (560 °C) by metalorganic chemical vapor deposition (MOCVD) is investigated. The lattice constant contracts and the growth rate decreases with increasing dithylzinc (DEZn) flow rate. To clarify the reason, the growth rates of InAs, AlAs, and GaAs components are examined. The growth rates of AlAs and GaAs components are almost constant; only that of InAs dramatically decreases when the DEZn flow increases. This indicates that the incorporation of In is suppressed by the DEZn supply. The doping behavior during the growth is well fit by the surface adsorption-trapping model, which suggests that excess Zn atoms on the growth surface induce the reduction of the InAs component.
Fabrication of Large-Area CoNi Mold for Nanoimprint Lithography
Authors: Lee Jung-Ki , Cho Si-Hyeong , Rizwan Muhammad , Yoo Bong-Young , Park Jin-Goo
Published: January 2012

A cobalt–nickel (CoNi) alloy stamp of 140 mm diameter and 300 µm thickness was fabricated for nanoimprint lithography (NIL) from a Si mother mold with nanofeatures by using a stress-free electroforming method. CoNi alloys were electrodeposited in a chloride bath, and the effect of the flow velocity of a plating solution on CoNi film stress was investigated. The compositions of CoNi alloy films were investigated by changing the flow rate and bath concentration of CoCl2. The stress of the CoNi deposit was reduced to almost zero in an electrolyte containing 0.008 M CoCl2 in the flow rate range of 1–2 m/s. The multiple duplication of a stress-free CoNi alloy stamp was carried out without the use of a costly Si mother mold. Duplicated patterns on the CoNi alloy stamp were compared with those of the Si mother mold by field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM).
Label-Free Acetylcholine Image Sensor Based on Charge Transfer Technology for Biological Phenomenon Tracking
Authors: Takenaga Shoko , Tamai Yui , Okumura Koichi , Ishida Makoto , Sawada Kazuaki
Published: January 2012

A 32 ×32 charge-transfer enzyme-type acetylcholine (ACh) image sensor array was produced for label-free tracking of images of ACh distribution and its performance in repeatable measurements without enzyme deactivation was examined. The proposed sensor was based on a charge-transfer-type pH image sensor, which was modified using an enzyme membrane (acetylcholine esterase, AChE) for each pixel. The ACh image sensor detected hydrogen ions generated by the ACh–AChE reaction. A polyion complex membrane composed of poly(L-lysine) and poly(4-styrenesulfonate) was used to immobilize the enzyme on the sensor. The improved uniformity and adhesion of the polyion complex membrane were evaluated in this study. As a result, temporal and spatial fluctuations of the ACh image sensor were successfully minimized using this approach. The sensitivity of the sensor was 4.2 mV/mM, and its detection limit was 20 µM. In five repeated measurements, the repeatability was 8.8%.
Localized Surface Plasmon Resonance Dew Sensor for Use Under Low Humidity Conditions
Authors: Nagasaki Hideaki , Kaneko Sin , Iwami Kentaro , Umeda Norihiro
Published: January 2012

We fabricated a localized surface plasmon resonance dew sensor and examined its optical characteristics under low humidity conditions. The sensor consists of a silver film (100 nm thick) deposited on a self-assembled monolayer of variously sized silica particles. The sensor measures dew condensation by determining two parameters: absorbance at 900.3 nm and wavelength shift of an absorbance spectrum peak. A sensor fabricated with 400-nm-diameter silica particles exhibits a high optical refractive index sensitivity of 462.6 nm/RIU. In the cooling experiments at the dew point of -13.04 °C, the sensor exhibits an absorbance changing temperature equivalent to the dew point as well as a chilled mirror dew sensor and an absorbance peak wavelength shift at -7.50 °C. Thus, the proposed sensor can detect micro-dew condensation, which is undetectable by a conventional chilled mirror dew sensor.
Myostatin-null mice exhibit delayed skin wound healing through the blockade of transforming growth factor-β signaling by decorin
Authors: Zhang Chen , Tan Chek Kun , McFarlane Craig , Sharma Mridula , Tan Nguan Soon , Kambadur Ravi
Published: January 2012

Myostatin (Mstn) is a secreted growth and differentiation factor that belongs to the transforming growth factor-β (TGF-β) superfamily. Mstn has been well characterized as a regulator of myogenesis and has been shown to play a critical role in postnatal muscle regeneration. Herein, we report for the first time that Mstn is expressed in both epidermis and dermis of murine and human skin and that Mstn-null mice exhibited delayed skin wound healing attributable to a combination of effects resulting from delayed epidermal reepithelialization and dermal contraction. In epidermis, reduced keratinocyte migration and protracted keratinocyte proliferation were observed, which subsequently led to delayed recovery of epidermal thickness and slower reepithelialization. Furthermore, primary keratinocytes derived from Mstn-null mice displayed reduced migration capacity and increased proliferation rate as assessed through in vitro migration and adhesion assays, as well as bromodeoxyuridine incorporation and Western blot analysis. Moreover, in dermis, both fibroblast-to-myofibroblast transformation and collagen deposition were concomitantly reduced, resulting in a delayed dermal wound contraction. These decreases are due to the inhibition of TGF-β signaling. In agreement, the expression of decorin, a naturally occurring TGF-β suppressor, was elevated in Mstn-null mice; moreover, topical treatment with TGF-β1 protein rescued the impaired skin wound healing observed in Mstn-null mice. These observations highlight the interplay between TGF-β and Mstn signaling pathways, specifically through Mstn regulation of decorin levels during the skin wound healing process. Thus we propose that Mstn agonists might be beneficial for skin wound repair.
ERK acts in parallel to PKCδ to mediate the connexin43-dependent potentiation of Runx2 activity by FGF2 in MC3T3 osteoblasts
Authors: Niger Corinne , Buo Atum M. , Hebert Carla , Duggan Brian T. , Williams Mark S. , Stains Joseph P.
Published: January 2012

The gap junction protein, connexin43 (Cx43), plays an important role in skeletal biology. Previously, we have shown that Cx43 can enhance the signaling and transcriptional response to fibroblast growth factor 2 (FGF2) in osteoblasts by increasing protein kinase C-δ (PKCδ) activation to affect Runx2 activity. In the present study, we show by luciferase reporter assays that the ERK signaling cascade acts in parallel to PKCδ to modulate Runx2 activity downstream of the Cx43-dependent amplification of FGF2 signaling. The PKCδ-independent activation of ERK by FGF2 was confirmed by Western blotting, as was the Cx43-dependent enhancement of ERK activation. Consistent with our prior observations for PKCδ, flow cytometry analyses show that Cx43 overexpression enhances the percentage of phospho-ERK-positive cells in response to FGF2, supporting the notion that shared signals among gap junction-coupled cells result in the enhanced response to FGF2. Western blots and luciferase reporter assays performed on osteoblasts cultured under low-density and high-density conditions revealed that cell-cell contacts are required for Cx43 to amplify ERK activation and gene transcription. Similarly, inhibition of gap junctional communication with the channel blocker 18β-glycyrrhetinic acid attenuates the Cx43-dependent enhancement of Runx2-transcriptional activity. In total, these data underscore the importance of cell-cell communication and activation of the ERK and PKCδ pathways in the coordination of the osteoblast response to FGF2 among populations of osteoblasts.
Differential determinants for coupling of distinct G proteins with the class B secretin receptor
Authors: Garcia Gene L. , Dong Maoqing , Miller Laurence J.
Published: January 2012

The secretin receptor is a prototypic class B G protein-coupled receptor that is activated by binding of its natural peptide ligand. The signaling effects of this receptor are mediated by coupling with Gs, which activates cAMP production, and Gq, which activates intracellular calcium mobilization. We have explored the molecular basis for the coupling of each of these G proteins to this receptor using systematic site-directed mutagenesis of key residues within each of the intracellular loop regions, and studying ligand binding and secretin-stimulated cAMP and calcium responses. Mutation of a conserved histidine in the first intracellular loop (H157A and H157R) markedly reduced cell surface expression, resulting in marked reduction in cAMP and elimination of measurable calcium responses. Mutation of an arginine (R153A) in the first intracellular loop reduced calcium, but not cAMP responses. Mutation of a dibasic motif in the second intracellular loop (R231A/K232A) had no significant effects on any measured responses. Mutations in the third intracellular loop involving adjacent lysine and leucine residues (K302A/L303A) or two arginine residues separated by a leucine and an alanine (R318A/R321A) significantly reduced cAMP responses, while the latter also reduced calcium responses. Additive effects were elicited by combining the effective mutations, while combining all the effective mutations resulted in a construct that continued to bind secretin normally, but that elicited no significant cAMP or calcium responses. These data suggest that, while some receptor determinants are clearly shared, there are also distinct determinants for coupling with each of these G proteins.