bluuebunny/crossref_metadata_2025 huggingface dataset:
Post‐processing and assembly of reflective microdisplays
Authors: Schuck Miller , Kazlas Peter , Radler Michael , McKnight Douglas , Johnson Kristina
Published: May 2006

Abstract— The performance and manufacturability of reflective displays can be enhanced by planarization, post‐processing, and integrated assembly. Simplified methods for planarization and assembly of liquid‐crystal‐on‐silicon (LCOS) microdisplays using polymeric resins are presented. Spin‐cast benzocyclobutene (BCB) resin shows a six‐fold reduction in step height on the surface of a typical LCOS backplane, at a cost significantly less than chemical mechanical polishing. Methods for dry‐etching low‐resistance contacts to the underlying circuitry and depositing high‐reflectivity mirrors have been developed. In addition, photo‐definable BCB resin has been utilized as both a spacer and adhesive technology in miniature‐display assembly. Cell‐gap thicknesses of 0.9–2.4 μm with 50–100‐nm cell‐gap variation and bonding shear strengths of 3200 ± 460 psi have been demonstrated, leading to wafer‐scale assembly of LCOS cells. The photo‐BCB spacer and adhesive technology is compatible with common liquid‐crystal‐alignment techniques. In this paper, the methods and results of LCOS backplane planarization, post‐processing, and integrated display assembly are described.
Electro‐optical properties of a twisted hybrid aligned nematic mode for reflective liquid crystal displays
Authors: Kim Young Jin , Park Soon‐Mo , Lee Sin‐Doo
Published: May 2006

Abstract—A twisted hybrid aligned (THA) mode is proposed for reflective liquid‐crystal displays. In the reflective configuration, a single polarizer and a reflective electrode are used to achieve electrooptical switching between the black and white states in the THA mode of a chiral nematic liquid crystal. Numerical simulations are performed to optimize the cell parameters such as the cell thickness and the amount of the twist in the hybrid geometry. The reflective THA mode is found to give wider viewing and faster response characteristics than a twisted nematic one. The role of an optical retardation film on device performance of such a reflective THA cell is also discussed.
Generalized mixed‐mode reflective LCDs with large cell gaps and high contrast ratios
Authors: Kwok H. S. , Chen J. , Yu F. H. , Huang H. C.
Published: May 2006

Abstract— A generalized mixed twisted‐nematic/birefringent‐effect mode reflective LCD is presented. This new mode encompasses all previously published reflective nematic LCD modes and is clearly shown on the parameter space diagrams. We also discuss how to obtain operating conditions of this generalized mixed‐mode display with large cell gaps, low color dispersion, and high contrast at low voltages. This operating mode is particularly suitable for reflective crystalline‐silicon‐backplane active‐matrix LCDs.
A reflective color STN‐LCD with a single polarizer and double retardation films
Authors: Fujita S. , Yamaguchi H. , Mizuno H. , Ohtani T. , Sekime T. , Hatanaka T. , Ogawa T.
Published: May 2006

Abstract— A reflective color STN‐LCD with a single polarizer and double retardation films has been investigated. The double retardation films arranged in front of the LC layer enabled the LCD to contain reflective electrodes inside the panel. This configuration achieves a bright image with no parallax. A new construction of a reflective STN‐LCD with a single polarizer has been developed by means of our own method in which the color difference ΔE* as the optimizing parameter has been used. Further, RGB color filters have been newly designed for our reflective LCD, and an aluminum (Al) layer has been introduced as a reflective electrode. As a result, we have realized a 7.8‐in.‐diagonal reflective color STN‐LCD (640 × 480) which has 15% reflectance, 14:1 contrast ratio, 4096‐color capability, and sufficient color gamut. It has been confirmed that the single‐polarizer reflective color STN‐LCD has sufficient performance for mobile business tools. We believe that it will be a key device for this application.
The Gyricon rotating ball display
Authors: Sheridon N. K. , Richley E. A. , Mikkelsen J. C. , Tsuda D. , Crowley J. M. , Oraha K. A. , Howard M. E. , Rodkin M. A. , Swidler R. , Sprague R.
Published: May 2006

Abstract— The Gyricon display consists of hemispherical black and white (bichromal) balls contained in individual liquid‐filled cavities and disposed to orient in an electrical field. This bistable reflective light display currently has a diffuse reflectance of more than 18% and a contrast ratio of more than 6:1. The viewing angle approaches that of paper. A new method of fabricating the bichromal balls has enabled practical realization of large‐area high‐quality displays.
Improvement of field‐emission properties by formation of Nb‐silicide layer on silicon‐tip FEAs
Authors: Park J. S. , Lee S. , Ju B. K. , Oh M. H. , Jang J. , Jeon D.
Published: May 2006

Abstract— Metal silicide on silicon‐tip field‐emission arrays (FEAs) seems to be a promising way to improve the performance of the silicon‐tip FEAs. The niobium‐silicide layer was formed on a silicon surface. The Nb‐silicide FEAs were prepared by a silicidation process. The formation of the Nb‐silicide layer on a silicon surface was confirmed by using X‐ray diffractometry (XRD). The current‐voltage characteristics and the current fluctuation were measured under an ultra‐high‐vacuum environment using a Kiethley SMU 237 meter. The turn‐on voltage of silicon‐tip FEAs was decreased from 64 to 47 V by the formation of the Nb‐silicide layer on silicon tips, and the emission current fluctuation (2%) was more stable than that of conventional silicon‐tip FEAs.
The influence of ambient gases during the frit‐sealing cycle on the emission characteristics of Mo‐FEAs
Authors: Lee N. Y. , Kim B. C. , Jung J. H. , Kang M. S. , Kim H. , Ju B. K. , Lee Y. H. , Oh M. H. , Jang J. , Ahn S.
Published: May 2006

Abstract— A 3.5‐in. full‐color field‐emission display (FED) has been developed. The Spindt‐tip array with a pixelated anode produces uniform and clean image. Changes in electron emission characteristics before and after the frit‐sealing cycle were measured on the same field‐emitter arrays (FEAs). Properties of thin Mo films after frit sealing in various gaseous ambients were estimated by AFM, AES, SIMS, and XPS. The possibility of applying Ar as an ambient gas during the frit‐sealing cycle for vacuum packaging of field emission displays (FEDs) was reported. A set of uniquely printed spacers with high aspect ratios was fabricated on ITO‐coated glass for high‐vacuum packaging. The low‐voltage phosphor was tested at an anode voltage of 300 V. Finally, full‐color images of 64 gray scales will be demonstrated.
Optimized ITO thin films from ultra‐high‐density single‐phase targets
Authors: Lupton D. F.
Published: May 2006

Abstract— Fundamental requirements of sputter targets are discussed with regard to the mechanisms of conductance and transmission in ITO films. A novel, fully integrated process for the manufacture of targets is described which ensures excellent, highly reproducible sputtering characteristics. The targets are characterized by ultra‐high uniform density, and they are closely matched to the crystal structure, charge‐carrier density, and oxygen stoichiometry of optimum ITO thin films.
Mechanism of color breakup in field‐sequential‐color projectors
Authors: Mori Mineo , Hatada Toyohiko , Ishikawa Kazuo , Saishouji Tosio , Wada Osamu , Nakamura Junichi , Terashima Nobuyoshi
Published: May 2006

Abstract— To investigate color breakup in field‐sequential‐color projectors, we measured the threshold of color fusion frequency relative to retinal velocity of the moving edge on the color flicker field. The characteristic changed as the velocity approached saccade. The result suggests that the mechanism of color breakup differs according to the velocity of the image on the retina.
High‐resolution AMLCD made with a‐Si:H TFTs and an Al gate and IZO structure
Authors: Kinoshita H. , Kitahara H. , Schleupen K. , Colgan E. G. , Nunes R. , Kodate M. , Takasugi S.
Published: May 2006

Abstract— Using a low‐cost a‐Si:H‐TFT process with an Al gate and IZO last structure, a direct‐view active‐matrix display with the highest information content has been fabricated in a phase‐2 mass production line at DTI Himeji. The display, a 16.3‐in.‐diagonal 200‐ppi QSXGA (quad SXGA) incorporates 7680 columns and 2048 rows. Each subpixel measures 42 μm (H) × 126 μm (V).
Displays for hand‐held portable electronic products
Authors: Akins R.
Published: May 2006

Abstract— The hand‐held electronic‐product field includes most telecommunication, palm computing, and navigation products, making this a large market for smaller displays (typically from 1 to 4 in. on the diagonal). Historically, this market has demanded displays with low power and cost, rather than high image quality, as evidenced by the historical dominance of monochrome TN and STN displays. However, within these constraints there is a strong trend toward larger displays capable of higher information content, including a migration toward low‐power color solutions.
Ultra‐low‐power STN‐LCDs using multiple‐line addressing for mobile telecommunication applications
Authors: Nakazawa A. , Tamai K. , Nagai M. , Kitamura M. , Hirai Y. , Matsuoka S. , Soda Y.
Published: May 2006

Abstract— Ultra‐low‐power‐consumption STN‐LCDs with high display quality driven by MLA (multiple line addressing) technique have been developed. They realized 3‐V driving voltage for 1/33 duty ratio and 5‐V driving voltage for 1/65 duty ratio. These are most suitable for mobile telecommunication applications.
Electro‐optic investigations of holographically formed PDLCs: The effect of monomer functionality on display performance
Authors: Bowley C. C. , Fontecchio A. K. , Crawford G. P. , Yuan H.
Published: May 2006

Abstract— We investigated the effect of monomer functionality on the electro‐optic performance of holographically formed polymer‐dispersed liquid crystals. Oligomers of functionality 2, 3, and 6 are mixed to yield oligomers of intermediate functionality. Reflection efficiency and critical field peaks are reported for an effective functionality of ∼4.5 SEM studies, allowing us to correlate these results to polymer morphology.
Numerical approach to the physical behavior of fluorinated nematic liquid crystals
Authors: Xu J. , Okada H. , Onnagawa H. , Sugimori S.
Published: May 2006

Abstract— A numerical approach to the physical behavior of fluorinated liquid crystals has been investigated. The molecular parameters, such as dipole moment and polarizability were calculated using a semiempirical molecular orbital (MO) method. Using these molecular parameters and the Maier‐Meier theory, the temperature dependence of the dielectric anisotropy divided by the order parameter (Δ∍/S) has been estimated. In addition, taking the temperature dependence of the order parameter S into account, the temperature dependence of the dielectric anisotropy Δ∍ has been estimated. The calculated results are in good agreement with experimental results.
Spatio‐temporal variation of VUV and IR emissions from surface‐discharge‐type ACPDP cell
Authors: Yoon C. K. , Seo J. H. , Kim J. K. , Chung W. J. , Yang J. H. , Whang K.‐W. , Jeong H. S.
Published: May 2006

Abstract— The spatio‐temporal variations of 147‐nm, 173‐nm, and IR emission images were obtained from He‐Xe and Ne‐Xe surface‐discharge‐type ACPDP cells. Differences between the 147‐nm, 173‐nm, and IR emission characteristics between He‐Xe and Ne‐Xe gas mixtures were observed and explained by the difference of Xe mobility and dimer reaction coefficients in two cases.
Proposal for a 3‐D display with accommodative compensation: 3DDAC
Authors: Shiwa Shinichi , Omura Katsuyuki , Kishino Fumio
Published: May 2006

Abstract— This paper proposes a novel binocular‐disparity three‐dimensional (3‐D) display with accommodative compensation (3DDAC) to achieve fatigue‐free viewing. The display principle is based both on detecting gaze points and moving the display screen to the gaze depth in real time. Gaze detection is discussed with respect to whether eyeball rotation occurs or not, and screen motion is discussed with respect to whether the screen is real or a virtual image. In an experimental setup, a 3‐D computer‐graphics image was produced to evaluate the accommodation effect. The gaze position was fixed at the center of the field of view, and the display depth was controlled by a z‐buffer value of the pixel focused on. The display screen was then moved, as a virtual image, by back‐and‐forth movements of a relay lens. It was determined that the perceived sharpness of the image increased for the proposed display mode.
The Food Industry's Solution to the Obesity Epidemic: Take a Walk
Authors: Myers Douglas J.
Published: May 2006

An internationally known obesity expert recently delivered a lecture on strategies for reversing the obesity epidemic at a large public university. His view was that a reduction in exercise, not an increase in intake, has caused the epidemic. He stated that dieting strategies have largely been failures because they asked too much of people. A better solution, he suggested, is to teach people to pursue the more attainable goal of increasing their caloric output by a mere 100 calories a day. To achieve this, he designed a Web-based program, sponsored by a giant soda corporation and an international agribusiness conglomerate, which instructs individuals to take a walk.
Bp's Baku-Tbilisi-Ceyhan Pipeline: The New Corporate Colonialism
Authors: Marriott James , Muttitt Greg , Dunn Mary Lee
Published: May 2006

An international campaign was waged questioning the benefits of BP's Baku-Tbilisi-Ceyhan pipeline in an effort to avoid a “zone of sacrifice” there. This article is an offshoot of that effort and explains the contemporary struggle over the pipeline project. The authors describe the project's background and evaluate the actual and potential impacts of the project in which they consider eight areas. They also assess BP's capacity to confront resistance to the pipeline.
Effect of an alkyl substituted in salen ligands on 1,4‐Cis selectivity and molecular weight control in the polymerization of 1,3‐butadiene with (salen)Co(II) complexes in combination with methylaluminoxane
Authors: Endo Kiyoshi , Kitagawa Takahiro , Nakatani Kenji
Published: May 2006

The effect of an alkyl substituted in the aromatic ring of the salen ligand on the polymerization of butadiene (Bd) with (salen)Co(II) complexes in combination with methylaluminoxane (MAO) was investigated. The activity for the polymerization of Bd was influenced significantly by the introduction of alkyl groups at the 3,3′,5,5′‐positions in the aromatic ring of the salen ligand, and both the polymerization rate and 1,4‐cis contents increased in the following order with respect to the alkyl group: H < CH3 < t‐C4H9. This is in good agreement with the bulkiness of the alkyl groups. The activity for the polymerization of the (salen)Co(II) complex possessing t‐C4H9 at the 3,3′‐positions was higher than that of the (salen)Co(II) bearing t‐C4H9 at the 5,5′‐positions. Thus, the introduction of bulky substituents at the 3,3′‐positions of the salen ligand was an important factor in achieving both high activity and high 1,4‐cis selectivity in the polymerization of Bd with (salen)Co(II) complexes in combination with MAO. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4088–4094, 2006
Glycoconjugated polymer: Synthesis and characterization of poly(vinyl saccharide)‐block‐polystyrene‐block‐poly(vinyl saccharide) as an amphiphilic ABA triblock copolymer
Authors: Narumi Atsushi , Otsuka Issei , Matsuda Takeshi , Miura Yutaka , Satoh Toshifumi , Kaneko Noriaki , Kaga Harumi , Kakuchi Toyoji
Published: May 2006

Styrene (St) was polymerized with α,α′‐bis(2′,2′,6′,6′‐tetramethyl‐1′‐piperidinyloxy)‐1,4‐diethylbenzene (1) as an initiator (bulk, [St]/]1] = 570) at 120 °C for 5.0 h to obtain polystyrene having 2,2,6,6‐tetramethylpiperidiloxy moieties on both sides of the chain ends (2) with a number‐average molecular weight (Mn) of 14,300 and a polydispersity index [weight‐average molecular weight/number‐average molecular weight (Mw/Mn)] of 1.14. 4‐Vinylbenzyl glucoside peracetate (3a) was polymerized with 2 as a macromolecular initiator and dicumyl peroxide (DCP) as an accelerator in chlorobenzene at 120 °C. The polymerization with the [3a]/[2]/[DCP] ratio of 30/1/1.2 for 5 h afforded a product in a yield of 73%; it was followed by purification with preparative size exclusion chromatography to provide the ABA triblock copolymer containing the pendant acetyl glucose on both sides of the chain ends (4a; Mn = 21,000, Mw/Mn = 1.16). Similarly, the polymerization of 4‐vinylbenzyl maltohexaoside peracetate produced the ABA triblock copolymer containing the pendant acetyl maltohexaose on both side of the chain end (4b; Mn = 31,800, Mw/Mn = 1.11). Polymers 4a and 4b were modified by deacetylation into amphiphilic ABA triblock copolymers containing the pendant glucose and maltohexaose as hydrophilic segment, 5a and 5b, respectively. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3978–3985, 2006
Polyfluorenes containing tetraphenylthiophene segments: Synthesis, photophysics, and electroluminescence
Authors: Mikroyannidis John A.
Published: May 2006

2,5‐Bis(4‐bromophenyl)‐3,4‐diphenylthiophene was synthesized from benzyl chloride and sulfur and through the subsequent bromination of the intermediate 2,3,4,5‐tetraphenylthiophene. It was condensed with 2,7‐dibromo‐9,9‐dihexylfluorene via a nickel‐mediated Yamamoto coupling reaction to afford a new series of statistical copolymers with various compositions. In addition, poly(9,9‐dihexylfluorene) (PF) was synthesized under the same conditions for comparison. All the polymers were soluble in common organic solvents such as tetrahydrofuran (THF), chloroform, and dichloromethane. Their glass‐transition temperatures increased with an increase in the tetraphenylthiophene (TPT) content in the polymers, and they were 63–149 °C. The solutions of the polymers in THF emitted intense blue light with a photoluminescence maximum at 418–440 nm and quantum yields of 0.32–0.62. Thin films of the polymers with TPT fractions lower than 20 mol % emitted blue‐green light with two well‐resolved peaks at 445 and 520 nm and an optical band gap of about 2.85 eV. A thin film of the polymer with aTPT fraction of 50 mol % emitted pure blue light with a maximum at 419 nm and an optical band gap of 3.28 eV. An enhancement of the light‐emitting‐diode brightness by a factor of ∼8 with respect to that of PF was achieved in apolymer containing 5 mol % TPT. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4015–4026, 2006
New chiral [N,N,N]‐ligand containing titanium/zirconium precatalysts for 1‐hexene polymerization
Authors: Sudhakar Padmanabhan , Sundararajan Govindarajan
Published: May 2006

The ring‐opening reaction of (S)‐N‐tosyl‐2‐phenylaziridine by benzylamine in ethanol at 80 °C resulted in the formation of the (S,S)‐bis(N‐tosyl‐2‐amino‐2‐phenylethyl)benzylamine ligand in a 60% yield. The corresponding titanium complex, 1‐TiCl2, was prepared by the reaction of the dilithiated parent ligand with TiCl4. This precatalyst, in combination with methylaluminoxane, was capable of polymerizing 1‐hexene with good activities, resulting in the formation of good yields of low‐dispersity, high‐molecular‐weight polymers at low temperatures but higher yields of lower molecular weight polymers at higher temperatures. 1H and 13C NMR spectra of the polymers suggested high isotacticity and predominant chain termination via β‐hydride elimination. The enantiomerically pure catalysts, (R,R)‐1‐TiCl2 and (S,S)‐1‐TiCl2, showed nearly identical polymerization results at various polymerization temperatures. However, when the catalyst was prepared from a racemic ligand, the obtained polymers had lower molecular weights with a bimodal distribution. This observation suggested diastereomeric aggregation of the racemic catalyst, which was well supported by the NMR studies, and a modified Arrhenius plot (the natural logarithm of the number‐average molecular weight vs the reciprocal of the temperature) also showed sigmoidal behavior, indicating the existence of two or more active species. Analogous zirconium precatalysts showed similar results in the polymerization of 1‐hexene. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4006–4014, 2006
Living radical emulsion polymerization using the nanoprecipitation technique: An extension to atom transfer radical polymerization
Authors: Chan‐Seng Delphine , Georges Michael K.
Published: May 2006

Living radical polymerizations of styrene were performed under emulsion atom transfer radical polymerization conditions with latexes prepared by a nanoprecipitation technique recently developed for the stable free‐radical polymerization process. Latexes were prepared by the precipitation of a solution of low‐molecular‐weight polystyrene in acetone into a solution of a surfactant in water. The resulting particles were swollen with styrene and then heated. The effects of various surfactants and hydrophobic ligands, the reaction temperature, and the ligand/copper(I) bromide ratio were studied. The best results were obtained with the nonionic surfactant Brij 98 in combination with the hydrophobic ligand N,N‐bis(2‐pyridylmethyl)octadecylamine and a ligand/copper(I) bromide ratio of 1.5 at a reaction temperature of 85–90 °C. Under these conditions, latexes with good colloidal stability with average particle diameters of 200 nm were obtained. The molecular weight distributions of the polystyrenes were narrow, although the experimental molecular weights were slightly larger than the theoretical ones because not all the macroinitiator appeared to reinitiate. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4027–4038, 2006
Synthesis and properties of polyimides bearing acid groups on long pendant aliphatic chains
Authors: Yasuda Tomohiro , Li Yi , Miyatake Kenji , Hirai Michiko , Nanasawa Masato , Watanabe Masahiro
Published: May 2006

A series of novel polyimide electrolytes having long pendant sulfo‐ or phosphoalkoxy groups were synthesized for fuel‐cell applications. Sulfodecyloxy‐, phosphodecyloxy‐, and sulfophenoxydodecyloxy‐substituted benzidine monomers were synthesized from dihydroxybenzidine. These monomers were copolymerized with naphthalene tetracarboxylic dianhydride and fluorenylidene dianiline to give the corresponding polyimides. A flexible, ductile, and self‐standing membrane was obtained via casting from the polyimide solution. Because the acid groups were on long pendant side chains and away from the main chains, the polyimide membrane showed improved oxidative and hydrolytic stability in comparison with the polyimides with sulfonic acid groups on the main chains or on the short side chains. High thermal stability (no glass‐transition temperature and a decomposition temperature > 200 °C) was also obtained. The polyimide membrane displayed high proton conductivity of 10−1 S cm−1 at 120 °C. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3995–4005, 2006
Synthesis and characterization of new aromatic polyamides bearing crown ethers or their dipodal counterparts in the pendant structure. II. Benzo‐15‐crown‐5 and ortho‐bis[2‐(2‐ethoxyethoxy)ethoxy]benzene
Authors: Calderón Verónica , García Félix , De la Peña José L. , Maya Eva M. , Lozano Ángel E. , de la Campa José G. , de Abajo Javier , García José Miguel
Published: May 2006

This article describes the synthesis and characterization of two diacid monomers, each containing a benzo‐15‐crown‐5 subunit or its dipodal counterpart. Both novel monomers were reacted with technical aromatic diamines with Yamazaki's direct polyamidation method to render modified polyisophthalamides with high molecular weights containing side moieties of cyclic and acyclic ethylene oxide sequences. All the polymers were soluble in aprotic polar solvents and showed high glass‐transition temperatures in the range of 190–345 °C. The polymers with side crown ethers showed much higher glass‐transition temperatures than those with acyclic linear side ethylene oxide arms. The chemical composition, particularly with respect to the diamine and the open or closed character of the pendent ethylene oxide sequence, also affected other general properties such as the mechanical resistance, mechanical modulus, or water absorption. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4063–4075, 2006
Synthesis of laterally attached side‐chain liquid‐crystalline polynorbornenes with high mesogen density by ring‐opening metathesis polymerization
Authors: Pugh Coleen , Zhu Pukun , Kim Guehyun , Zheng Joe X. , Rubal Michael J. , Cheng Stephen Z. D.
Published: May 2006

(±)‐exo,endo‐5,6‐Bis{[[11′‐[2″,5″‐bis[2‐(3′‐fluoro‐4′‐n‐alkoxyphenyl)ethynyl]phenyl]undecyl]oxy]carbonyl}bicyclo[2.2.1]hept‐2‐ene (n = 1–12) monomers were polymerized by ring‐opening metathesis polymerization in tetrahydrofuran at room temperature with Mo(CHCMe2Ph)(N‐2,6‐iPr2Ph)(OtBu)2 as the initiator to produce polymers with number‐average degrees of polymerization of 8–37 and relatively narrow polydispersities (polydispersity index = 1.08–1.31). The thermotropic behavior of these materials was independent of the molecular weight and therefore representative of that of a polymer at approximately 15 repeat units. The polymers exhibited an enantiotropic nematic mesophase when n was 2 or greater. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4076–4087, 2006
Non-planar fronts in Boussinesq reactive flows
Authors: Berestycki Henri , Constantin Peter , Ryzhik Lenya
Published: May 2006

We consider the reactive Boussinesq equations in a slanted cylinder, with zero stress boundary conditions and arbitrary Rayleigh number. We show that the equations have non-planar traveling front solutions that propagate at a constant speed. We also establish uniform upper bounds on the burning rate and the flow velocity for general front-like initial data for the Cauchy problem.
Effects of fluid shear stress on mRNA expression of carbonic anhydrase II in polarized rat osteoclasts
Authors: Zhang Qinghong , Liang Xing , Zhu Baoming , Dong Qiang , Xu Ling , Xia Lu , Hu Jian , Fu Jun , Liu Mengtao
Published: May 2006

The present study was designed to determine the effects of fluid shear stress on the mRNA expression of carbonic anhydrase II (CAII) in polarized rat osteoclasts. Cellular morphology of the polarized osteoclasts generated by a mechanical anatomical technique was examined by tartrate‐resistant acid phosphatase (TRAP) staining and the osteoclastic resorption of dentine slices. The polarized osteoclasts were then stress‐loaded by using a flow shear stress device newly developed by the osteoclast research group (patent number 200420034438; China), at 9 dyne/cm2 for various time periods [0 (control group), 15, 30, 60, and 120 min], or at various stress levels [0 (control), 0.9, 2.9, 8.7, and 26.3 dyne/cm2] for 30 min. The mRNA expression of CAII was quantified using real‐time fluorescent quantitative PCR (RT‐PCR) and the data were analyzed with SPSS 12.0 software. The polarized osteoclasts were larger than regular monocytes (about 30 μm diameter) with irregular configuration, and the majority of polarized osteoclasts appeared to be spherical and had approximately 2–20 nuclei. The TRAP positive polarized osteoclasts showed asymmetrical red staining in the cytoplasm, and had many filaments and vacuoles. These cells formed resorptive pits in dentine slices. The levels of CAII mRNA expression were shown to be time‐dependent, with the E+5 copy numbers being 7.88 ± 0.09, 11.14 ± 0.12, 15.83 ± 0.18, 1.94 ± 0.02, and 1.37 ± 0.01 in cells treated at 9 dyne/cm2 for 0, 15, 30, 60 and 120 min, respectively (P < 0.05). The levels of CAII mRNA expression (E+5 copy numbers) in cells treated with the stress levels of 0, 0.9, 2.9, 8.7 and 26.3 dyne/cm2 were 7.97 ± 0.201, 11.26 ± 0.688, 15.94 ± 0.201, 31.88 ± 1.496, and 45.08 ± 2.639, respectively (P < 0.05). These results indicate that there is a relationship between the fluid shear stress and the mRNA expression of CAII in polarized rat osteoclasts.
Clinical trials update from the American College of Cardiology: Darbepoetin alfa, ASTEROID, UNIVERSE, paediatric carvedilol, UNLOAD and ICELAND
Authors: Cleland John G.F. , Coletta Alison P. , Nikitin Nikolay P. , Clark Andrew L.
Published: May 2006

This article provides information and a commentary on trials relevant to the pathophysiology, prevention and treatment of heart failure, presented at the American College of Cardiology 55th Annual Scientific Session held in March 2006. All reports should be considered as preliminary data, as analyses may change in the final publication.

Darbepoetin alfa increased haemoglobin levels in heart failure patients and improved some aspects of quality of life compared to placebo. In the ASTEROID study rosuvastatin significantly reduced LDL‐cholesterol levels and induced regression of atherosclerosis in patients with CAD. Rosuvastatin also produced a significant reduction in LDL‐cholesterol levels in heart failure patients in the UNIVERSE study, but had no effect on left ventricular remodelling compared to placebo. The paediatric carvedilol study failed to show a benefit of carvedilol in children with heart failure. Ultrafiltration produced a greater weight and fluid loss than intravenous diuretics in heart failure patients with volume overload in the UNLOAD study but did not exert a greater improvement in breathlessness; however, ultrafiltration did reduce readmission rates. The ICELAND MI study showed that CMR imaging was more sensitive than ECG or clinical criteria for detecting myocardial infarction.
Characterization of dimeric ATP synthase and cristae membrane ultrastructure from Saccharomyces and Polytomella mitochondria
Authors: Dudkina Natalya V. , Sunderhaus Stephanie , Braun Hans-Peter , Boekema Egbert J.
Published: May 2006

There is increasing evidence now that F1F0 ATP synthase is arranged in dimers in the inner mitochondrial membrane of several organisms. The dimers are also considered to be the building blocks of oligomers. It was recently found that the monomers in beef and the alga Polytomella ATP synthase dimer make an angle of ∼40° and ∼70°, respectively. This arrangement is considered to induce a strong local bending of the membrane. To further understand the packing of dimers into oligomers we performed an electron microscopy analysis of ATP synthase dimers purified from Saccharomyces cerevisiae. Two types of dimers were found in which the angle between the monomers is either ∼90° or ∼35°. According to our interpretation, the wide‐angle dimers (70–90°) are “true‐dimers” whereas the small‐angle dimers (35–40°) rather are “pseudo‐dimers”, which represent breakdown products of two adjacent true dimers in the oligomer. Ultrathin sectioning of intact Polytomella mitochondria indicates that the inner mitochondrial or cristae membrane is folded into lamellae and tubuli. Oligomers of ATP synthase can arrange in a helical fashion in tubular‐shaped cristae membranes. These results strongly support the hypothesized role of ATP synthase oligomers in structural determination of the mitochondrial inner membrane.
Rsp5 regulates expression of stress proteins via post‐translational modification of Hsf1 and Msn4 in Saccharomyces cerevisiae
Authors: Haitani Yutaka , Shimoi Hitoshi , Takagi Hiroshi
Published: May 2006

Rsp5 is an essential E3 ubiquitin ligase in Saccharomyces cerevisiae and is known to ubiquitinate plasma membrane permeases followed by endocytosis and vacuolar degradation. We previously isolated the rsp5 mutant that is hypersensitive to various stresses, suggesting that Rsp5 is involved in degradation of stress‐induced abnormal proteins. Here, we analyzed the ability to refold the proteins by stress proteins in the rsp5 mutant. The transcription of stress protein genes in the rsp5 mutant was significantly lower than that in the wild‐type strain when exposed to temperature up‐shift, ethanol or sorbitol. Interestingly, the amounts of transcription factors Hsf1 and Msn4 were remarkably defective in the rsp5 mutant. These results suggest that expression of stress proteins are mediated by Rsp5 and that Rsp5 primarily regulates post‐translational modification of Hsf1 and Msn4.
The cyanobacterial principal σ factor region 1.1 is involved in DNA‐binding in the free form and in transcription activity as holoenzyme
Authors: Imashimizu Masahiko , Hanaoka Mitsumasa , Seki Asako , Murakami Katsuhiko S. , Tanaka Kan
Published: May 2006

Cyanobacterial principal σ factor, σA, includes a specifically conserved cluster of basic amino acids in the amino‐terminal extension called region 1.1. We found that the σA in a thermophilic cyanobacterium Thermosynechococcus elongatus BP‐1 binds DNA in the absence of the core RNA polymerase and that σA lacking region 1.1 is not able to bind DNA. This indicates that, in the cyanobacterium, region 1.1 participates in DNA‐binding, rather than inhibiting the interaction between free σ and DNA, as found in other principal σ factors of eubacteria. The results of in vitro transcription assays with the reconstituted RNA polymerase showed that region 1.1 reduces transcription activity from the cpc promoter.
Growth of Mytilus galloprovincialis after the Prestige oil spill
Authors: Peteiro Laura G. , Babarro José M.F. , Labarta Uxío , Fernández-Reiriz María José
Published: May 2006

Growth of mussel Mytilus galloprovincialis using raft culture was investigated for the first cultured generation following the Prestige oil spill off northwestern Spain. Seed from three natural populations along the Galician coastline, Pindo, Miranda, and Redes, was transplanted to a raft culture system in Ría de Ares-Betanzos. The physiological and biochemical status of mussels at the onset of culture and the degree of oil exposure three months after the spill (February 2003) have been described already, but here growth patterns of three populations sampled monthly from seeding to thinning-out (March/August 2003) and from thinning-out to harvest (August 2003/February 2004) were assessed. Mussels from Pindo (the area most affected by the oil spill) showed significantly less growth by weight than the other populations, resulting in a lower yield at harvest. The percentage of mussels classified as “large” in the Pindo population at harvest was also significantly less than that of the other two mussel populations.
Trust in public institutions in Russia: The lowest in the world
Authors: Shlapentokh Vladimir
Published: May 2006

The article’s topic is the attitudes of the Russians toward their social institutions. As it will be shown, Russia is a country, much more than any other, that mistrusts its social institutions, political institutions in particular. There is no one institution that can garner more than 40 to 50 percent of the nation’s trust. Indeed, in terms of their lack of confidence in social institutions, the Russians are behind not only the most advanced countries in the world, but even countries known for their unstable political systems, such as Colombia or Nigeria.
Reform, corruption, and growth: Why corruption is more devastating in Russia than in China
Authors: Larsson Tomas
Published: May 2006

This article explains why massive political corruption appears to be incompatible with economic growth in Russia but compatible with very rapid economic growth in China. The common assumption is that corruption is bad for economic performance. So how can we explain the puzzling contrast between Russia and China? Is Russia being more severely “punished” for its corruption than China? If so, why? This article demonstrates that three intervening factors—comparative advantage, the organization of corruption, and the nature of rents—determines the impact of corruption on economic performance, and that these factors can explain the divergent outcomes. The article thereby offers an alternative to statist explanations of the Russia-China paradox.
Bryophyte relationships with environmental and structural variables in Tasmanian old-growth mixed eucalypt forest
Authors: Turner P. A. M. , Kirkpatrick J. B. , Pharo E. J.
Published: May 2006

The species richness and species composition of bryophytes (mosses and liverworts) was recorded at 33 sites in Tasmanian old growth mixed eucalypt forest. A total of 202 bryophyte taxa were recorded, consisting of 115 liverworts and 87 mosses. This constitutes approximately one third of the total bryophyte flora for Tasmania. Mean liverwort species richness per site was higher than moss species richness. Latitude was found to be a positive predictor in all multiple regression models of bryophyte, moss and liverwort species richness. Mean annual temperature and rainfall of the driest month were positive predictors for bryophyte and liverwort species richness. Basal area of the treefern Dicksonia antarctica Labill. was a negative predictor of liverwort species richness. Latitude, variables relating to moisture, mean annual temperature, rainfall of the driest month and basal area of Dicksonia antarctica were the most significant components in predicting variation in bryophyte, moss and liverwort species composition. There were few relationships between the variables of canopy cover and soil nutrients and bryophyte species richness and composition. Substrate variables were found to be important components in predicting variation in moss and bryophyte species composition.
Genetic variation, taxonomy and mountain-hopping of four bipolar Carex species (Cyperaceae) analysed by AFLP fingerprinting
Authors: Vollan K. , Heide O. M. , Lye K. A. , Heun M.
Published: May 2006

The bipolar sedges Carex canescens, C. echinata, C. lachenalii and C. magellanica (including C. paupercula) were analysed by amplified fragment length polymorphisms (AFLPs). The genetic variation of Carex populations from northern Europe was compared with those from the farthest locations in the Southern Hemisphere (i.e. Australia, New Zealand and Chile). This DNA fingerprinting of 152 plants yielded 223 AFLP bands, which were scored as present/absent and converted to Jaccard’s dichotomy coefficients. Unweighted pair-group methods using arithmetic averages (UPGMA), neighbour-joining (NJ), and principal coordinate analysis (PCA) were performed. We obtained AFLP-based separations of the four Carex species that were in full agreement with previous morphology-based taxonomy. A large number of species-specific bands occurred. Hemisphere-specific bands were not identified, but all analyses showed a clear distinction between populations collected from the Northern and Southern Hemispheres. The results are discussed in relation to the mountain-hopping hypothesis, which is one possible mechanism underlying the bipolar distribution of those species.
The effect of fire-related germination cues on the germination of a declining forest understorey species
Authors: Tierney David A.
Published: May 2006

Fire is an important component of most Australian terrestrial ecosystems and exerts a major influence on plant recruitment in these systems. Seeds of species from Australian heath, woodland and grassland systems have a diverse response to fire-related germination cues. Australian forests are also subject to fire events. However, for species of these forests, the diversity of germination responses to fire-related germination cues is poorly known. This study reports on the germination response of seed of Prostanthera askania Conn (Lamiaceae), a species restricted to eucalypt forests and eucalypt forest–rainforest boundaries. Smoke and heat shock negatively interact in relation to the germination level of P. askania seed. Thus, in this study, smoke elevated the germination level of P. askania seed only in the absence of applied heat treatments. P. askania seed also displayed high levels of dormancy, but unlike some related species, smoke effected a partial dormancy break. These results suggest that low-intensity fire may be optimal for the germination of this species. This is supported by an observed germination response of this species to a low-intensity fire and low-intensity fire may be a common feature of species of rainforest–eucalypt forest boundaries. However, other species in these systems have germination levels maximised by cues associated with high-intensity fire. Shifts in rainforest boundaries, reported effects of weed invasion on fire intensity in rainforests and the reported decline of species as a result of increased fire intensity suggest that P. askania may have been disadvantaged by a range of habitat changes associated with fire regimes since European settlement.
Synaptic tetraspan vesicle membrane proteins are conserved but not needed for synaptogenesis and neuronal function in
Caenorhabditis elegans
Authors: Abraham Christian , Hutter Harald , Palfreyman Mark T. , Spatkowski Gabriele , Weimer Robby M. , Windoffer Reinhard , Jorgensen Erik M. , Leube Rudolf E.
Published: May 2006

Tetraspan vesicle membrane proteins (TVPs) comprise a major portion of synaptic vesicle proteins, yet their contribution to the synaptic vesicle cycle is poorly understood. TVPs are grouped in three mammalian gene families: physins, gyrins, and secretory carrier-associated membrane proteins (SCAMPs). In
Caenorhabditis elegans
, only a single member of each of these families exists. These three nematode TVPs colocalize to the same vesicular compartment when expressed in mammalian cells, suggesting that they could serve overlapping functions. To examine their function,
C. elegans
null mutants were isolated for each gene, and a triple mutant was generated. Surprisingly, these animals develop normally and exhibit normal neuronal architecture and synaptic contacts. In addition, functions of the motor and sensory systems are normal as determined by pharmacological, chemotaxis, and thermotaxis assays. Finally, direct electrophysiological analysis of the neuromuscular junction revealed no phenotype in the TVP mutants. We therefore conclude that TVPs are not needed for the basic neuronal machinery and instead may contribute to subtle higher order functions.
PKCε increases endothelin converting enzyme activity and reduces amyloid plaque pathology in transgenic mice
Authors: Choi Doo-Sup , Wang Dan , Yu Gui-Qui , Zhu Guofen , Kharazia Viktor N. , Paredes J. Peter , Chang Wesley S. , Deitchman Jason K. , Mucke Lennart , Messing Robert O.
Published: May 2006

Deposition of plaques containing amyloid β (Aβ) peptides is a neuropathological hallmark of Alzheimer's disease (AD). Here we demonstrate that neuronal overexpression of the ε isozyme of PKC decreases Aβ levels, plaque burden, and plaque-associated neuritic dystrophy and reactive astrocytosis in transgenic mice expressing familial AD-mutant forms of the human amyloid precursor protein (APP). Compared with APP singly transgenic mice, APP/PKCε doubly transgenic mice had decreased Aβ levels but showed no evidence for altered cleavage of APP. Instead, PKCε overexpression selectively increased the activity of endothelin-converting enzyme, which degrades Aβ. The activities of other Aβ-degrading enzymes, insulin degrading enzyme and neprilysin, were unchanged. These results indicate that increased neuronal PKCε activity can promote Aβ clearance and reduce AD neuropathology through increased endothelin-converting enzyme activity.
Signature whistle shape conveys identity information to bottlenose dolphins
Authors: Janik V. M. , Sayigh L. S. , Wells R. S.
Published: May 2006

Bottlenose dolphins (Tursiops truncatus) develop individually distinctive signature whistles that they use to maintain group cohesion. Unlike the development of identification signals in most other species, signature whistle development is strongly influenced by vocal learning. This learning ability is maintained throughout life, and dolphins frequently copy each other’s whistles in the wild. It has been hypothesized that signature whistles can be used as referential signals among conspecifics, because captive bottlenose dolphins can be trained to use novel, learned signals to label objects. For this labeling to occur, signature whistles would have to convey identity information independent of the caller’s voice features. However, experimental proof for this hypothesis has been lacking. This study demonstrates that bottlenose dolphins extract identity information from signature whistles even after all voice features have been removed from the signal. Thus, dolphins are the only animals other than humans that have been shown to transmit identity information independent of the caller’s voice or location.
The maximum number of torque-generating units in the flagellar motor of
Escherichia coli
is at least 11
Authors: Reid Stuart W. , Leake Mark C. , Chandler Jennifer H. , Lo Chien-Jung , Armitage Judith P. , Berry Richard M.
Published: May 2006

Torque is generated in the rotary motor at the base of the bacterial flagellum by ion translocating stator units anchored to the peptidoglycan cell wall. Stator units are composed of the proteins MotA and MotB in proton-driven motors, and they are composed of PomA and PomB in sodium-driven motors. Strains of
Escherichia coli
lacking functional stator proteins produce flagella that do not rotate, and induced expression of the missing proteins leads to restoration of motor rotation in discrete speed increments, a process known as “resurrection.” Early work suggested a maximum of eight units. More recent indications that WT motors may contain more than eight units, based on recovery of disrupted motors, are inconclusive. Here we demonstrate conclusively that the maximum number of units in a motor is at least 11. Using back-focal-plane interferometry of 1-μm polystyrene beads attached to flagella, we observed at least 11 distinct speed increments during resurrection with three different combinations of stator proteins in
E. coli
. The average torques generated by a single unit and a fully induced motor were lower than previous estimates. Speed increments at high numbers of units are smaller than those at low numbers, indicating that not all units in a fully induced motor are equivalent.
Genetic effects of chronic habitat fragmentation in a wind-pollinated tree
Authors: Jump Alistair S. , Peñuelas Josep
Published: May 2006

Habitat fragmentation poses a serious threat to plants through genetic changes associated with increased isolation and reduced population size. However, the longevity of trees, combined with effective seed or pollen dispersal, can enhance their resistance to these effects. The European beech (
Fagus sylvatica
) dominates forest over large regions of Europe. We demonstrate that habitat fragmentation in this species has led to genetic bottlenecks and the disruption of the species' breeding system, leading to significantly elevated levels of inbreeding, population divergence, and reduced genetic diversity within populations. These results show that, in contrast with the findings of previous studies, forest fragmentation has a negative genetic impact, even in this widespread, wind-pollinated tree. The identification of significant effects of forest fragmentation in beech demonstrates that trees are not at reduced risk from environmental change. This should be accounted for in the management of remaining natural and seminatural forest throughout the world.