bluuebunny/crossref_metadata_2025 huggingface dataset:
Observation of interfacial electrostatic field‐induced changes in the silicon dielectric function using spectroscopic ellipsometry
Authors: Price J. , Lysaght P. S. , Song S. C. , Diebold A. C. , An Y. Q. , Downer M. C.
Published: March 2008

This work investigates the capability of spectroscopic ellipsometry to measure charge trapping centers in thin dielectric films. Specific interfacial electrostatic fields, induced by electrons injected into charge trapping states at the interface, have been identified that directly affect the underlying silicon substrate critical points. The effect of a field‐induced change in the silicon fundamental absorption edge due to different processing conditions affecting the oxygen vacancy defects at the interface is presented. Measuring the field‐induced change in the silicon dielectric function between a sample with a 2 nm HfO2 film as‐deposited and the same sample after a 1000 °C anneal in an N2 ambient reveals that a stronger interfacial field is present for the as‐deposited HfO2 film. These results are consistent with the understanding that high temperature anneals work well to passivate oxygen vacancy defects at the silicon/HfO2 interface. Finally, we compare our results with Second Harmonic Generation where specific resonant features are identifiable with electric field enhancements at the same interface. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Comparative investigation of Stöber silica Langmuir–Blodgett films as optical model structures
Authors: Nagy N. , Deák A. , Hámori A. , Hórvölgyi Z. , Fried M. , Petrik P. , Bársony I.
Published: March 2008

Mono‐ and multilayered Stöber silica Langmuir–Blodgett (LB) films were investigated by Spectroscopic Ellipsometry (SE) and Optical Waveguide Lightmode Spectroscopy (OWLS) comparatively. The effective refractive index and film thickness were determined from the results of multiparameter fitting of SE and OWLS spectra, and verified by reflectance spectroscopy measurements. LB layers of silica nanospheres are excellent model structures for the experimental verification of the validity of the Effective Medium Approximation (EMA) methods in SE evaluation. Since the structure of the LB films is nearly ideally close‐packed, even single layer Maxwell–Garnett EMA offers a sufficiently adequate description of this structure. Deviation from the ideally calculated porosity in the LB monolayer can be interpreted in terms of an average distance between individual spheres (coverage) in the uniform layer (assuming monodisperse particles). In case of the evaluations of OWLS measurements homogeneous single layer model can not be used because of the exponential form of the sensing evanescent field. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Error analysis of a simple and accurate optical coherent ellipsometer
Authors: Nee Soe‐Mie F. , Yu Chih‐Jen , Wu Jheng‐Syong , Huang Hong‐Sheng , Chou Chien
Published: March 2008

The polarization modulation of optical coherent ellipsometry (OCE) is provided by the coupling between two highly correlated orthogonal polarizations with slightly different frequencies. Error of the sample‐analyzer (SA) OCE is analyzed using the Stokes–Mueller formalism to include samples with roughness. Sample's depolarization will degrade the coherency of the incident two‐frequency laser beam, and the degradation is more serious for smaller sin 2ψ. For the simplest SA OCE with the analyzer angle at 45° from both polarizations, the misalignment of the analyzer affects only the measured dc signal but not the beat signal; and the extinction of the analyzer affects only the beat signal but not the dc signal. This SA OCE is used to measure the polarization properties for a few samples to demonstrate its applicability. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Generation of droplet‐free high‐power pulsed sputtering (HPPS) glow plasma with several tens of kilowatts
Authors: Yukimura K. , Mieda R. , Tamagaki H. , Okimoto T.
Published: March 2008

A droplet free metallic plasma source is promising for enhanced adhesion of films with a smooth coating surface. This paper concerns a highly ionized metallic plasma source using a pulsed Penning discharge. A high‐power pulsed sputtering (HPPS) glow discharge plasma is generated using electric‐ and magnetic‐field interactions. The metallic species are sputtered by the energetic argon ion bombardment, followed by their ionization in as short as approximately 3 μs. The plasma source is compact in size (approximately 60 × 60 × 60 mm3) and the plasma is arc‐free. The glow plasma is generated at a gap with a length of 10 mm. The magnetic field at the gap is approximately 0.3 T. A pulsed power source with a rectangular‐shaped voltage‐output is used. Fundamental electrical and optical characteristics are obtained. The glow voltage and current are approximately –0.43 kV and 37 A at 30 μs, respectively, which corresponds to a peak power of approximately 16 kW, where the applied voltage –1.2 kV and a current limiting series resistance is 20 Ω. The consumed energy is approximately 0.41 J, which corresponds to an average power of 250 W at a repetition rate of 625 Hz. The power and energy are changed by circuit conditions. In order to increase the consumed power, the current limiting‐resistance is decreased to be 3 Ω, the peak power is increased to approximately 70 kW with a power density of 2.9 kW/cm2, where a current density is 4.5 A/cm2. The ambient gas is argon at a pressure of 2 Pa. In the emission spectra, singly‐ and doubly‐ionized titanium ions are observed, following the generation of argon ions, which shows the ionization of sputtered titanium species. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantum degeneracy of polaritons in a GaAs based Microcavity
Authors: Bajoni Daniele , Senellart Pascale , Lemaître Aristide , Bloch Jacqueline
Published: March 2008

Polariton quantum degeneracy is obtained in a GaAs Microcavity by pulsed resonant excitation of the excitonic reservoir. Time resolved emission is monitored in this stimulated regime along the polariton branch.

Analyzing the polariton population distribution for different time delays, we conclude that polariton thermalization is not achieved and that the dynamics is governed by the scattering kinetics from the reservoir into the polariton trap. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Current spreading, heat transfer, and light extraction in multi‐pixel LED array
Authors: Bogdanov M. V. , Bulashevich K. A. , Evstratov I. Yu. , Karpov S. Yu.
Published: March 2008

Using simulation, we have investigated into the current spreading, heat transfer, and light emission in a high‐power light‐emitting diode (LED) with an interdigitated multipixel array (IMPA) chip design. The main advantages of such LEDs compared with conventional square‐shaped ones, like a lower series resistance and a higher emission efficiency at high currents, are interpreted in terms of current spreading and local active region overheating originated from the current crowding typical for planar LED dice. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spectral and time resolved scanning near‐field microscopy of broad area 405 nm InGaN laser diode dynamics
Authors: Braun Harald , Meyer Tobias , Scholz Dominik , Schwarz Ulrich T. , Brüninghoff Stefanie , Lell Alfred , Strauß Uwe
Published: March 2008

Ridge widths of GaN laser diodes (LDs) are typically in the order of few mm. In contrast to GaAs material systems, beam quality of GaN broad area lasers is still a critical point. By time resolved scanning near‐field optical microscopy (SNOM) on pulsed electrically pumped LDs with different ridge widths we observe dynamic features caused by thermal and carrier induced changes of the refractive index like filamentation and lateral mode competition, which strongly influence the far‐field of the LDs. Using a high spectral resolution spectrometer we can additionally resolve the individual longitudinal modes of the laser spectrum both time resolved and correlated to the lateral position in the waveguide. Especially on samples with broad ridges we observe complex spectral and spatial dynamics of the laser mode like different filaments lasing on different longitudinal mode combs. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Beam quality of blue InGaN laser for projection
Authors: Strauss Uwe , Eichler Christoph , Rumbolz Christian , Lell Alfred , Lutgen Stephan , Tautz Sönke , Schillgalies Marc , Brüninghoff Stefanie
Published: March 2008

The blue light sources of choice for laser projection will be long wavelength nitride lasers because of their high wall plug efficiency and their small form factor compared to blue light sources using second harmonic generation. High quality of the far field is required for laser projection. However, optical confinement of GaN/AlGaN structures becomes increasingly difficult when wavelength shifts from 405 nm to the true blue spectrum. We will show excellent far fields by suppression of higher order laser modes and by improved waveguiding, respectively. We present simulations of laser modes as a function of ridge width. The slow axis far field is improved by absorber layers that guarantee in‐plane values of M2 < 1.5. Sufficient vertical confinement of the laser light by thick cladding layers is necessary to suppress laser modes guided within the substrate. We present 440 nm lasers for projection with threshold currents of 20 mA and slope efficiencies more than 0.8 W/A. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural properties of aluminum nitride bulk single crystals grown by PVT
Authors: Bickermann M. , Epelbaum B. M. , Filip O. , Heimann P. , Nagata S. , Winnacker A.
Published: March 2008

Defect analysis is performed on 1‐inch diameter bulk AlN crystals grown on AlN‐on‐SiC templates by physical vapour transport. The mean density of threading dislocations as evaluated by wet chemical etching is about 4 × 104 cm–2; mosaicity of the crystals is mostly inherited from the quality of the SiC and the AlN‐on‐SiC template used as seed. Comparing crystals grown without and with growth optimization, the dislocation topography is significantly different, and in crystals grown under optimized conditions, low angle grain boundaries have a more pronounced tendency to dissolve into dislocation bunches and thus a lower density at the crystal top. This corresponds to a ‘coarser’. mosaic structure as observed in X‐ray rocking curve measurements. In summary, AlN bulk crystals grown on AlN‐on‐SiC templates under optimized conditions show not only significant improvement in cracking mitigation and optical homogeneity, but also in structural quality, within a single growth run. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Piezoelectric actuation of all‐nitride MEMS
Authors: Tonisch K. , Buchheim C. , Niebelschütz F. , Donahue M. , Goldhahn R. , Cimalla V. , Ambacher O.
Published: March 2008

We present a MEMS technology based on (GaN/)AlGaN/GaN–heterostructures. Thereby the lower GaN layer represents the mechanical active layer, while the upper GaN and AlGaN layers supply the piezoelectrically active layers for actuation and the confinement of a 2D electron gas (at the lower interface). The 2DEG serves as back electrode for the piezoelectric actuation and as read–out, since it is modulated by the mechanical oscillation. The upper AlGaN and GaN layer both contribute to the total piezoelectric response, which was determined by piezoelectric force microscopy. The electrical field distribution throughout the heterostructure was determined by means of electroreflectance. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High sensitivity of photoluminescence‐ excitation spectroscopy for probing effects of plasma‐induced surface damages on carrier transport in AlxGa1–xN/GaN heterostructures
Authors: Takeuchi H. , Shirahama T. , Yamamoto Y. , Kamo Y. , Kunii T. , Oku T. , Tanaka H. , Nakayama M.
Published: March 2008

We demonstrate that photoluminescence‐excitation (PLE) spectroscopy is applicable to probe effects of the surface damages on the carrier transport in AlxGa1–xN/GaN heterostructures by systematically characterizing as‐grown and plasma‐exposed samples. The characterization of the surface morphology with atomic force microscopy clarifies that the plasma exposure modifies the atomic steps and pits on the AlxGa1–xN surface. The PLE spectrum of the as‐grown sample measured at the energy of the photoluminescence from the GaN layer shows a step rising from the AlxGa1–xN fundamental transition energy, which reflects the photogenerated‐carrier injection from the AlxGa1–xN layer to the GaN layer, while the rising step disappears in the plasma‐exposed sample. In contrast, the reflectance spectra are the same in the two samples; namely, the excitonic transition is hardly changed. Thus, it is concluded that PLE spectroscopy is highly sensitive to probe the carrier‐transport characteristics in the AlxGa1–xN/GaN heterostructure. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth and characterization of InCrN and (In,Ga,Cr)N
Authors: Kimura S. , Emura S. , Tokuda K. , Hiromura Y. , Hayakawa S. , Zhou Y. K. , Hasegawa S. , Asahi H.
Published: March 2008

InCrN and a new quaternary alloy (In,Ga,Cr)N were synthesized by molecular beam epitaxy. Their structural properties were studied with X‐ray diffraction and X‐ray absorption fine structure (XAFS). It was found that low temperature growth enables the growth of InCrN and (In,Ga,Cr)N with higher Cr contents, while they were not crystallized at higher substrate temperature (450 °C). XAFS studies suggest that Cr atoms substitute on cation sites and no trace of locally formed secondary phases, such as Cr cluster, CrN (NaCl type) and Cr2N, in the grown InCrN and (In,Ga,Cr)N layers. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Creativity, inquiry, or accountability? Scientists' and teachers' perceptions of science education
Authors: Taylor Amy R. , Jones M. Gail , Broadwell Bethany , Oppewal Tom
Published: March 2008

Although there have been numerous studies that indicate the benefits of teachers and students working with scientists, there is little research that documents scientists' views of science education, science teacher preparation, and the goals of science education. Furthermore, little is known about how scientists' views of science education may differ from those held by science teachers. Through the use of semistructured interviews, the perceptions of 37 scientists from diverse science domains and 21 middle and high school science teachers were explored. Participating scientists expressed concerns about the variability in quality of teaching, programs, and resources available for science instruction. Scientists expressed a desire for teachers to have more experience conducting science research and developing their own critical thinking skills. When asked what goals are most important for science education, 40% of the scientists emphasized that teachers should make science fun and exciting for their students. Science teachers' perceptions of science education were compared with the scientists' perceptions. Thirty percent of the teachers agreed with the scientists that too much variability in program or instructional quality exists in science education. Seventy‐six percent of the science teachers also thought there is a need to teach critical thinking skills, but more importantly there is a need to inspire creativity and a desire to learn science in students. Both teachers and scientists expressed concerns about how high‐stakes accountability inhibits efforts to improve science education. © 2008 Wiley Periodicals, Inc. Sci Ed 92:1058–1075, 2008
A varying‐coefficient model for the evaluation of time‐varying concomitant intervention effects in longitudinal studies
Authors: Wu Colin O. , Tian Xin , Bang Heejung
Published: March 2008

Concomitant interventions are often introduced during a longitudinal clinical trial to patients who respond undesirably to the pre‐specified treatments. In addition to the main objective of evaluating the pre‐specified treatment effects, an important secondary objective in such a trial is to evaluate whether a concomitant intervention could change a patient's response over time. Because the initiation of a concomitant intervention may depend on the patient's general trend of pre‐intervention outcomes, regression approaches that treat the presence of the intervention as a time‐dependent covariate may lead to biased estimates for the intervention effects. Borrowing the techniques of Follmann and Wu (Biometrics 1995; 51:151–168) for modeling informative missing data, we propose a varying‐coefficient mixed‐effects model to evaluate the patient's longitudinal outcome trends before and after the patient's starting time of the intervention. By allowing the random coefficients to be correlated with the patient's starting time of the intervention, our model leads to less biased estimates of the intervention effects. Nonparametric estimation and inferences of the coefficient curves and intervention effects are developed using B‐splines. Our methods are demonstrated through a longitudinal clinical trial in depression and heart disease and a simulation study. Copyright © 2008 John Wiley & Sons, Ltd.
Bayesian semiparametric regression for longitudinal binary processes with missing data
Authors: Su Li , Hogan Joseph W.
Published: March 2008

Longitudinal studies with binary repeated measures are widespread in biomedical research. Marginal regression approaches for balanced binary data are well developed, whereas for binary process data, where measurement times are irregular and may differ by individuals, likelihood‐based methods for marginal regression analysis are less well developed. In this article, we develop a Bayesian regression model for analyzing longitudinal binary process data, with emphasis on dealing with missingness. We focus on the settings where data are missing at random (MAR), which require a correctly specified joint distribution for the repeated measures in order to draw valid likelihood‐based inference about the marginal mean. To provide maximum flexibility, the proposed model specifies both the marginal mean and serial dependence structures using nonparametric smooth functions. Serial dependence is allowed to depend on the time lag between adjacent outcomes as well as other relevant covariates. Inference is fully Bayesian. Using simulations, we show that adequate modeling of the serial dependence structure is necessary for valid inference of the marginal mean when the binary process data are MAR. Longitudinal viral load data from the HIV Epidemiology Research Study are analyzed for illustration. Copyright © 2008 John Wiley & Sons, Ltd.
Factors influencing partner selection in strategic alliances: the moderating role of alliance context
Authors: Shah Reshma H. , Swaminathan Vanitha
Published: March 2008

The growth of alliances has generated considerable interest in this topic among both academics and practitioners. While multiple factors may affect alliance success, partner selection emerges as one of the most influential. Previous studies on alliances present general models that assume the factors (e.g., trust, commitment, complementarity, financial payoff) that drive partner attractiveness and, in turn, the likelihood of selection, are consistent across varying alliance projects and situations. In contrast, the present study proposes a contingency approach grounded in management control theory that suggests the criteria managers use in choosing alliance partners will vary by alliance project type. Specifically, it introduces a framework that addresses when and why managers select partners with certain, specific characteristics. The results of the present study strongly support hypotheses that the critical criteria for assessing alliance partner attractiveness and selection vary depending on the differential levels of process manageability and outcome interpretability inherent in a strategic alliance. Implications for theory and practice are discussed. Copyright © 2008 John Wiley & Sons, Ltd.
Color Control of Natural Fluorescent Proteins by Photonic Crystals
Authors: Blum Christian , Mosk Allard P. , Nikolaev Ivan S. , Subramaniam Vinod , Vos Willem L.
Published: March 2008

The emission of fluorescent proteins inside photonic crystals is studied. It is demonstrated that the apparent emission color of the fluorescent protein can be controlled externally by the photonic crystal. With increasing crystal lattice parameter, the appearance of the proteins turns from orange to red, and suddenly to green. The dramatic color changes agree with the theoretically expected redistribution of light escaping around the stop band of the photonic crystal. Our experiments show the potential of combining biological systems with nanophotonics. This “biophotonic engineering” may be extended to control emission rates and complex Förster energy‐transfer systems obtained by protein engineering.
Professional identity development theory and doctoral education
Authors: Colbeck Carol L.
Published: March 2008

This chapter explores the benefits of enhancing doctoral students' abilities to exploit the synergies among their multiple academic identities.
Applying lessons from professional education to the preparation of the professoriate
Authors: Golde Chris M.
Published: March 2008

The pedagogies used in professional education to develop students' identities in the domains of knowledge, skills, and values can help doctoral programs better prepare future faculty members.
Graduate education and community engagement
Authors: O'Meara KerryAnn
Published: March 2008

Windows of opportunity for integrating community engagement throughout the doctoral career are offered in this chapter along with a description of the knowledge, skills, and value orientations needed for future faculty to become engaged scholars.
Networking to develop a professional identity: A look at the first‐semester experience of doctoral students in business
Authors: Sweitzer Vicki L.
Published: March 2008

Bringing together mentoring, social networks, and professional identity theories, this chapter explores how messages received from network partners influenced the professional identity development of business doctoral students in their first semester of study.
Direct Syntheses of Bis(tetraphenylphosphonium) and Bis(ethyltriphenylphosphonium) Hexabromo‐diselenates(II), [PPh4]2[Se2Br6] and [PEtPh3]2[Se2Br6]. The Crystal Structure of [PEtPh3]2[Se2Br6]
Authors: Janickis Vitalijus , Herberhold Max , Milius Wolfgang
Published: March 2008

Brown crystals of [PPh4]2[Se2Br6] (1) and [PEtPh3]2[Se2Br6] (2) were obtained when selenium and bromine reacted in acetonitrile solution in the presence of tetraphenylphosphonium bromide and ethyltriphenylphosphonium bromide, respectively. The crystal structure of 2 has been determined by X‐ray methods and refined to R = 0.0420 for 4161 reflections. The crystals are monoclinic, space group P21/n with Z = 2 and a = 13.055(3) Å, b = 12.628(3) Å, c = 13.530(3) Å, β = 92.40(3)° (293(2) K). In the solid state structure of 2 the dinuclear hexabromo‐diselenate(II) anion is centrosymmetric and consists of two distorted almost square‐planar SeBr4 units sharing a common edge through two bridging Br atoms. The terminal SeII–Br bond distances are found to be 2.419(1) and 2.445(1) Å, the bridging μBr–SeII bond distances 2.901(1) and 2.802(1) Å.
Synthesis and Crystal Structure of (CH3NH3)2[Cu(NO3)4]: a Rare Example of a Tetranitratocuprate(II) with a Light Cation of the Type M2[Cu(NO3)4]
Authors: Steinhauser Georg , Karaghiosoff Konstantin , Klapötke Thomas M.
Published: March 2008

The reaction of methylammonium nitrate and copper(II) nitrate pentahemihydrate in concentrated nitric acid yields the novel bis(monomethylammonium) tetranitratocuprate(II). By evaporation of the nitric acid at elevated temperatures single crystals suitable for crystal structure analysis by X‐ray diffraction were obtained. The crystal structure shows a clear Jahn‐Teller distortion in the octahedral nitratocuprate anion.
The Influence of Substituents at C2 Carbon Atom of Thiosemicarbazones {R(H)C2=N3‐N2(H)‐C1(=S)‐N1H2} on their Dentacy in PtII/PdII Complexes: Synthesis, Spectroscopy, and Crystal Structures
Authors: Lobana Tarlok S. , Bawa Gagandeep , Hundal Geeta , Zeller M.
Published: March 2008

The coordination chemistry of platinum(II) with a series of thiosemicarbazones {R(H)C2=N3‐N2(H)‐C1(=S)‐N1H2, R = 2‐hydroxyphenyl, H2stsc; pyrrole, H2ptsc; phenyl, Hbtsc} is described. Reactions of trans‐PtCl2(PPh3)2 precursor with H2stsc (or H2ptsc) in 1 : 1 molar ratio in the presence of Et3N base yielded complexes, [Pt(η3‐ O, N3, S‐stsc)(PPh3)] (1) and [Pt(η3‐ N4, N3, S‐ptsc)(PPh3)] (2), respectively. Further, trans‐PtCl2(PPh3)2 and Hbtsc in 1 : 2 (M : L) molar ratio yielded a different compound, [Pt(η2‐ N3, S‐btsc)(η1‐S‐btsc)(PPh3)] (3). Complex 1 involved deprotonation of hydrazinic (‐N2H‐) and hydroxyl (‐OH) groups, and stsc2− is coordinating via O, N3, S donor atoms, while complex 2 involved deprotonation of hydrazinic (‐N2H‐) and ‐N4H groups and ptsc2− is probably coordinating via N4, N3, S donor atoms. Reaction of PdCl2(PPh3)2 with Hbtsc‐Me {C6H5(CH3)C2=N3‐N2(H)‐C1(=S)‐N1H2} yielded a cyclometallated complex [Pd(η3‐C, N3, S‐btsc‐Me)(PPh3)] (4). These complexes have been characterized with the help of analytical data, spectroscopic techniques {IR, NMR (1H, 31P), U.V} and single crystal X‐ray crystallography (1, 3 and 4). The effects of substituents at C2 carbon of thiosemicarbazones on their dentacy and cyclometallation are emphasized.
[PdCl(TeMe2)3](BArF) – The First Structurally Characterized Palladium(II) Complex with TeMe2 Ligands
Authors: Bröring Martin , Kleeberg Christian
Published: March 2008

[PdCl(TeMe2)3]BArF (4) forms as the major tellurium containing product from the reaction of [(4‐Mebti)PdCl] with TeMe2 and Na(BArF) and is isolated by crystallization from the reaction mixture. At −20 °C, the compound forms orange columns from toluene/pentane, space group $P{\bar 1}$, with Z = 2. In the solid, the cationic [PdCl(TeMe2)3]+ complex ions show a non‐planar PdClTe3 coordination unit and are associated to dimers via weak Pd···Te interactions.
Zur Hydrolyse von 2,3‐Dihydro‐1,3‐di‐tert‐butyl‐4,5‐dimethylimidazol‐2‐yliden. Die Kristallstruktur von 1,3‐Di‐tert‐butyl‐4,5‐dimethylimidazoliumhydrogencarbonat
Authors: Abu‐Rayyan Ahmed , Abu‐Salem Qutaiba , Kuhn Norbert , Maichle‐Mößmer Cäcilia , Steimann Manfred , Henkel Gerald
Published: March 2008

On the Hydrolysis of 2,3‐Dihydro‐1,3‐di‐tert‐butyl‐4,5‐dimethylimidazol‐2‐ylidene. The Crystal Structure of 1,3‐Di‐tert‐butyl‐4,5‐dimethylimidazolium Bicarbonate

1,3‐Di‐tert‐butyl‐4,5‐dimethylimidazolium bicarbonate (7), formed on the exposure of 2,3‐dihydro‐1,3‐di‐tert‐butyl‐4,5‐dimethylimidazol‐2‐ylidene (6) towards air, is prepared on the reaction of 6 with ammonium bicarbonate; its crystal structure analysis reveals the presence of dimeric bicarbonate anions linked to each other and to the imidazolium ions with hydrogen bonds.
Trans‐ and cis‐ Cobalt(III), Iron(III), and Chromium(III) Complexes Based on α‐ and γ‐Diimine Schiff Base Ligands: Synthesis and Evaluation of the Complexes as Catalysts for Oxidation of L‐Cysteine
Authors: Abu‐Surrah Adnan S. , Abdel‐Halim Hamzeh M. , Al‐Qaisi Feda'a M.
Published: March 2008

The synthesis of a new series of trans and racemic cis isomers of cobalt(III)‐, iron(III)‐, and chromium(III)‐based complexes with the α‐ and γ‐diimine Schiff base ligands, N,N′‐bis(X)‐2,3‐butandiimine and N,N′‐bis(X)‐1,2‐phenyldiimine (X = cyclohexyl, 2‐isopropylphenyl, 1‐naphthyl) is described. To confirm the identity of the complexes prepared in the present study, a variety of techniques including elemental analysis, magnetic susceptibility, infrared‐, mass‐ (EI), and UV/Vis‐ spectroscopy have been utilized. Some of the isolated complexes have been evaluated as catalysts for the oxidation of L‐cysteine. Preliminary results showed that the metal atoms, geometry of the complexes, auxiliary substituents, and the backbone of the ligand influenced the rate of oxidation reaction.
Evidence‐based Management of Toxic Multinodular Goiter (Plummer’s Disease)
Authors: Porterfield John R. , Thompson Geoffrey B. , Farley David R. , Grant Clive S. , Richards Melanie L.
Published: March 2008

Background

Toxic multinodular goiter (Plummer’s disease) has posed challenges to surgeons, endocrinologists, and radiation oncologists since its description in 1913. A literature review with evidenced‐based methodology has not yet been reported.

Methods

A systematic review of the English literature from 1950 to 2007 and report of Mayo Clinic experience since 1950 was undertaken to establish evidence‐based recommendations for management.

Results

Surgery and radioactive iodine (RI) are both supported by level IV evidence in the treatment of solitary toxic nodules and toxic multinodular goiter, and treatment is determined by symptoms and co‐morbidities. No evidence suggests a difference in treatment outcome based on pretreatment clinical or subclinical hyperthyroidism. Level IV evidence supports thyroidectomy over RI for large goiters. When compressive symptoms are present, level IV evidence supports thyroidectomy for maximal symptom relief in patients at moderate risk. Occult malignancies are found in 2–3% of thyroidectomy specimens for Plummer’s disease. Despite technical reports of RI dose considerations, there are no prospective studies validating a dose formula. Ethanol ablation of toxic nodules in patients unfit for surgery is supported by level III evidence. Level V data suggest a cost benefit favoring surgery.

Conclusions

Treatment of Plummer’s disease with antithyroid medications, ethanol ablation, RI ablation, or surgery must balance the goals of therapy, durability of cure, relief of symptoms, risk of malignancy, and risk of complications. Between 1950 and 2006, 948 (70%) of 1,356 patients with Plummer’s disease have been treated surgically at Mayo Clinic.
Energy balance and weight regulation: genetics versus environment
Authors: Ravussin Eric , Bogardus Clifton
Published: March 2008

The prevalence of obesity is reaching epidemic proportions in many industrialized countries. There is growing evidence that, even if the trigger of this epidemic is found in changes in the environment, genes are interacting with the environment to cause weight gain. Studies of twins reared apart indicate that approximately two-thirds of the variability in BMI is attributed to genetic factors. From prospective studies in Pima Indians we can ascribe 12 % of the variability in BMI to metabolic rate, 5 % to fat oxidation, and another probable 10 % to the level of spontaneous physical activity. These data indicate that at least 40 % of the variability in BMI is related to genetic factors involved in the regulation of food intake and/or volitional activity. This indicates that the most likely successful therapy for obesity may target pathways of the regulation of food intake. Similarly, an environment favouring engagement in physical activity should be promoted.
Population studies of diet and obesity
Authors: Lissner Lauren , Heitmann Berit L. , Bengtsson Calle
Published: March 2008

Population-based research on diet, obesity and the metabolic syndrome is faced with accumulating evidence of biases that may profoundly affect results. One potential source of bias, which is often neglected in nutritional epidemiology, arises from self-selected study populations. Subjects who agree to participate in surveys may be at less risk of metabolic syndrome than those who refuse. Analogous to observations in adult populations, studies of schoolchildren have also yielded clear evidence of self-selection. Whether such selection patterns influence analytical results depends on how the biases relate to the dependent and independent variables being studied. Systematic dietary reporting error is another source of bias in studies of nutritional risk factors for disease. While obesity-related under-reporting bias is now well documented, less is known about whether specific foods and nutrients are disproportionately affected. However, two studies employing biomarkers for protein have suggested that obese subjects under-reported the proportion of energy from fat plus carbohydrate. This should alert epidemiologists to the possibility that a dual reporting bias may be present in studies of diet and disease: general under-reporting among obese subjects compounded by food-specific errors. In summary, biases due to self-selection and selective dietary under-reporting may produce consequences in epidemiological studies that are both unpredictable and complex. We conclude this review with recent findings involving dietary fat intake and regional adiposity in a population-based study of women. These preliminary results may have etiological relevance to the development of metabolic syndrome, but multiple biases of the type described previously may also be operating.
Fatty acids and insulin secretion
Authors: Grill Valdemar , Qvigstad Elisabeth
Published: March 2008

It has long been recognized that acute elevation of non-esterified fatty acids (NEFA) stimulates insulin secretion to a moderate extent both in vitro and in vivo. The effects of longer-term exposure to elevated fatty acids have, however, been investigated only recently. Our own studies in the rat have documented the time dependence of NEFA effects, with inhibition of glucose-induced insulin secretion being apparent after 6–24 h in vivo exposure to Intralipid or in vitro exposure to palmitate, oleate and octanoate. Evidence indicates that the inhibitory effects are coupled to fatty acid oxidation in B-cells, with ensuing reduction in glucose oxidation, in parallel with diminished activity of the pyruvate dehydrogenase enzyme. These findings were essentially confirmed in human pancreatic islets. In the db/db mouse, a model of type 2 diabetes with obesity, evidence was obtained for elevated NEFA playing a significant role in decreased glucose-induced insulin secretion. Evidence also indicates that elevated NEFA inhibit insulin biosynthesis and increase the proinsulin : insulin ratio of secretion. Results on experimentally induced elevations of NEFA in non-diabetic and diabetic humans are thus far inconclusive. Further studies are needed to ascertain the impact of elevated NEFA on insulin secretion in clinical settings.
Diet composition and insulin action in animal models
Authors: Storlien Len H. , Higgins J. A. , Thomas T. C. , Brown M. A. , Wang H. Q. , Huang X. F. , Else P. L.
Published: March 2008

Critical insights into the etiology of insulin resistance have been gained by the use of animal models where insulin action has been modulated by strictly controlled dietary interventions not possible in human studies. Overall, the literature has moved from a focus on macronutrient proportions to understanding the unique effects of individual subtypes of fats, carbohydrates and proteins. Substantial evidence has now accumulated for a major role of dietary fat subtypes in insulin action. Intake of saturated fats is strongly linked to development of obesity and insulin resistance, while that of polyunsaturated fats (PUFAs) is not. This is consistent with observations that saturated fats are poorly oxidized for energy and thus readily stored, are poorly mobilized by lipolytic stimuli, impair membrane function, and increase the expression of genes associated with adipocyte profileration (making their own home). PUFAs have contrasting effects in each instance. It is therefore not surprising that increased PUFA intake in animal models is associated with improved insulin action and reduced adiposity. Less information is available for carbohydrate subtypes. Early work clearly demonstrated that diets high in simple sugars (in particular fructose) led to insulin resistance. However, again attention has rightly shifted to the very interesting issue of subtypes of complex carbohydrates. While no differences in insulin action have yet been shown, differences in substrate flux suggest there could be long-term beneficial effects on the fat balance of diets enhanced in slowly digested/resistant starches. A new area of major interest is in protein subtypes. Recent results have shown that rats fed high-fat diets where the protein component was from casein or soy were insulin-resistant, but when the protein source was from cod they were not. These are exciting times in our growing understanding of dietary factors and insulin action. While it has been clear for some time that ‘oils ain't oils’, the same is now proving true for carbohydrates and proteins.
Dietary treatment of thrombogenic disorders related tothe metabolic syndrome
Authors: Marckmann Peter
Published: March 2008

The increased risk of coronary heart disease associated with the metabolic syndrome may be partially explained by prothrombotic deviations of the haemostatic system. Individuals with insulin resistance, dyslipidaemia and obesity are characterized by elevated plasma fibrinogen and factor VII coagulant activity levels and raised concentrations of plasminogen-activator inhibitor, the main inhibitor of endogenous fibrinolysis. These haemostatic abnormalities may be corrected with dietary treatment of the underlying clinical disorder. Dietary trials of diseased and healthy volunteers suggest that the optimal antithrombotic diet is a low-fat diet with a high content of foods rich in complex carbohydrates and dietary fibre. The dietary fatty acid composition has a profound effect on blood lipids, but seems of minor importance for the haemostatic system.
Dietary treatment of the metabolic syndrome — the optimal diet
Authors: Riccardi Gabriele , Rivellese A. A.
Published: March 2008

The treatment of the metabolic syndrome aims to improve insulin sensitivity and correct/prevent the associated metabolic and cardiovascular abnormalities. Since many individuals with the metabolic syndrome are overweight, dietary treatment should be primarily focused on weight reduction. This approach can improve insulin sensitivity and exert beneficial effects on all the other abnormalities clustering in the syndrome. Insulin sensitivity can also be influenced by diet composition. In this respect, the specific effects of the quality of dietary fat are of great interest, given the considerable evidence in experimental animals that saturated fat in the diet may lead to insulin resistance. In man, there is indirect evidence that a higher saturated fat intake is associated with impaired insulin action. Human studies have also attempted to evaluate the relationship between total fat intake and insulin sensitivity. They are consistent in showing that fat intake is correlated with both plasma insulin values (positively) and insulin sensitivity (negatively). However, these correlations are largely mediated by body weight. Conversely, intervention studies are consistent in showing that when total fat intake is moderately increased (from 20 to 40 %), no major effect is observed on insulin sensitivity. We have recently undertaken a large, multicentre intervention study in 162 healthy individuals given either a high-saturated-fat or a high-monounsaturated-fat diet for 3 months. It shows that a high-monounsaturated-fat diet significantly improves insulin sensitivity compared to a high-saturated-fat diet. However, this beneficial effect of monounsaturated fat disappears when total fat intake exceeds 38 % of total energy. Independently of its effects on insulin sensitivity, diet composition can influence the factors clustering in the metabolic syndrome. Dietary carbohydrate increases blood glucose levels, particularly in the postprandial period, and consequently also insulin levels and plasma triglycerides. The detrimental effects of a high-carbohydrate diet on plasma glucose/insulin, triglyceride/HDL or fibrinolysis occur only when carbohydrate foods with a high glycaemic index are consumed, while they are abolished if the diet is based largely on fibre-rich, low-glycaemic-index foods. In conclusion, weight reduction is a powerful measure for the treatment of metabolic syndrome. Moreover, the diet for the treatment of the metabolic syndrome should be limited in the intake of saturated fat, while high fibre/low-glycaemic-index foods should be used without specific limitations. Moderate amounts of monounsaturated fat could be permitted as they do not induce detrimental metabolic effects.
The Generic American Psycho
Authors: ELDRIDGE DAVID
Published: March 2008

Following Elizabeth Young's 1991 analysis of the controversy surrounding the publication of Bret Easton Ellis's American Psycho, this article discusses the efforts of the makers of the 2000 film adaptation to “rehabilitate” the novel. It explores the recognition of Mary Harron and Guinevere Turner that Patrick Bateman was constructed from the literary debris of a variety of “debased” genres, how they responded by constructing a specifically cinematic Bateman and how, in doing so, they renegotiated the “pigeonholes” of genre fiction originally used in hostile reviews to dismiss Ellis's authorial intent.
Lost Boys and Recovered Classics: Literary and Social Memory in Lorenzo Carcaterra's Sleepers (1995)
Authors: WILSON CHRISTOPHER P.
Published: March 2008

This essay explores the interplay of literary and social memory in Lorenzo Carcaterra's prison and revenge memoir, Sleepers (1995), in particular its appropriation of Alexander Dumas's The Count of Monte Cristo (1844–45) as both a literary template and a political marker. Monte Cristo is the central text in Carcaterra's rewriting of a long tradition of “bad-boy” narratives depicting juvenile dispossession, crime, and redemptive vigilantism. The essay also traces the transatlantic routes of Dumas in modern US popular culture, especially in Albert Kanter's Illustrated Classics, in light of Antonio Gramsci's theories of popular narrative and law.
Velocity and temperature derivatives in high- Reynolds-number turbulent flows in the atmospheric surface layer. Part 3. Temperature and joint statistics of temperature and velocity derivatives
Authors: GULITSKI G. , KHOLMYANSKY M. , KINZELBACH W. , LÜTHI B. , TSINOBER A. , YORISH S.
Published: March 2008

This is part 3 of our work describing experiments in which explicit information was obtained on all the derivatives, i.e. spatial derivatives, ∂/∂xj, and temporal derivatives, ∂/∂t, of velocity and temperature fields (and all the components of velocity fluctuations and temperature) at the Reynolds numberReλ~104.

This part is devoted to the issues concerning temperature with the emphasis on joint statistics of temperature and velocity derivatives, based on preliminary results from a jet facility and the main results from a field experiment. Apart from a number of conventional results, these contain a variety of results concerning production of temperature gradients, such as role of vorticity and strain, eigen-contributions, geometrical statistics such as alignments of the temperature gradient and the eigenframe of the rate-of-strain tensor, tilting of the temperature gradient, comparison of the true production of the temperature gradient with its surrogate. Among the specific results of importance is the essential difference in the behaviour of the production of temperature gradients in regions dominated by vorticity and strain. Namely, the production of temperature gradients is much more intensive in regions dominated by strain, whereas production of temperature gradients is practically independent of the magnitude of vorticity. In contrast, vorticity and strain are contributing equally to the tilting of the vector of temperature gradients.

The production of temperature gradients is mainly due to the fluctuative strain, the terms associated with mean fields are unimportant. It was checked directly (by looking at corresponding eigen-contributions and alignments), that the production of the temperature gradients is due to predominant compressing of fluid elements rather than stretching, which is true of other processes in turbulent flows, e.g. turbulent energy production in shear flows. Though the production of the temperature gradient and its surrogate possess similar univariate PDFs (which indicates the tendency to isotropy in small scales by this particular criterion), their joint PDF is not close to a bisector. This means that the true production of the temperature gradient is far from being fully represented by its surrogate. The main technical achievement is demonstrating the possibility of obtaining experimentally joint statistics of velocity and temperature gradients.
Influence of meteorological conditions on post-tonsillectomy haemorrhage
Authors: Racic G , Kurtovic D , Colovic Z , Dogas Z , Kardum G , Roje Z
Published: March 2008

Aim:

To evaluate the relationship between the incidence of primary post-tonsillectomy haemorrhage and the daily weather condition, over a five-year period.

Study design and setting:

This was a retrospective study carried out in the ENT department of the Split University Hospital between January 2000 and December 2004.

Results:

Out of 3377 patients undergoing tonsillectomy, primary post-operative haemorrhage occurred in 83 (2.5 per cent). The season, daily atmospheric pressure and daily change in atmospheric pressure did not have any significant influence on post-tonsillectomy haemorrhage incidence. However, there was a statistically significant increase in the incidence of primary post-operative haemorrhage when cyclonic conditions prevailed (p = 0.035).

Conclusion:

The incidence of primary post-tonsillectomy haemorrhage in our study population was 2.5 per cent. Avoiding tonsillectomy during cyclonic weather conditions may reduce the incidence of primary post-tonsillectomy haemorrhage.
Common or distinct deficits for auditory and visual hallucinations?
Authors: Badcock Johanna C. , Maybery Murray T.
Published: March 2008

The dual-deficit model of visual hallucinations (Collerton et al. target article) is compared with the dual-deficit model of auditory hallucinations (Waters et al., in press). Differences in cognitive mechanisms described may be superficial. Similarities between these models may provide the basis for a general model of complex hallucinations extended across disorders and modalities, involving shared (overlapping) cognitive processes.
Economic man – or straw man?
Authors: Binmore Ken
Published: March 2008

The target article by Henrich et al. describes some economic experiments carried out in fifteen small-scale societies. The results are broadly supportive of an approach to understanding social norms that is commonplace among game theorists. It is therefore perverse that the rhetorical part of the paper should be devoted largely to claiming that “economic man” is an experimental failure that needs to be replaced by an alternative paradigm. This brief commentary contests the paper's caricature of economic theory, and offers a small sample of the enormous volume of experimental data that would need to be overturned before “economic man” could be junked.
Catatonia is the Rosetta Stone of psychosis
Authors: Carroll Brendan T. , Carroll Tressa D.
Published: March 2008

Recurrent complex visual hallucinations (RCVH) represent a form of psychosis. It may be useful to compare RCVH to another form of psychosis, catatonia. Both include a long list of medical illnesses and have been examined using several different hypotheses. Catatonia has a variety of hypotheses, including neurocircuitry, neurochemistry, and an integrated neuropsychiatric hypothesis. This hypothesis for catatonia supports Collerton et al.'s Perception and Attention Deficit model (PAD) for RCVH.
On the limitations of quasi-experiments
Authors: Burnham Terence C. , Kurzban Robert
Published: March 2008

Although provocative, the data reported in Henrich et al.'s target article suffer from limitations, including the fact that the “selfishness axiom” is not an interesting null hypothesis, and the intrinsic limitations of quasi-experimental designs, in which random assignment is impossible. True experiments, in the laboratory or in the field, will continue to be crucial for settling core issues associated with human economic behavior.