bluuebunny/crossref_metadata_2025 huggingface dataset:
Inducible expression of a prostate cancer‐testis antigen, SSX‐2, following treatment with a DNA methylation inhibitor
Authors: Dubovsky Jason A. , McNeel Douglas G.
Published: October 2007

BACKGROUND

Active immunotherapies are one approach being developed as novel treatments for prostate cancer. Critical to the success of these therapies is the identification of appropriate target antigens. We have been seeking to identify immunologically recognized proteins, cancer‐testis antigens (CTA) in particular, in patients with prostate cancer that would be rational target antigens.

METHODS

Using a previously reported panel of 29 different CTA, we used sera from 98 patients with prostate cancer and 50 healthy male blood donor controls to detect CTA‐specific IgG. We then further evaluated the expression of one antigen, SSX‐2, in prostate cancer cell lines and tissues.

RESULTS

We identified IgG specific for NY‐ESO‐1, LAGE‐1, NFX‐2, and SSX‐2 in at least 1/98 individuals with prostate cancer. We demonstrated that SSX‐2 is a prostate CTA, and its expression is associated with metastatic prostate cancer. In addition, we report that the treatment of at least two human prostate cancer cell lines with the DNA methylation inhibitor 5‐aza‐2′‐deoxycytidine induced the expression of SSX‐2. In contrast, treatment of a normal prostate epithelial cell line (RWPE‐1) with 5‐aza‐2′‐deoxycytidine did not induce SSX‐2 expression.

CONCLUSIONS

Our findings suggest that SSX‐2 could be further pursued as an immunotherapeutic target in prostate cancer, and that treatment with 5‐aza‐2′‐deoxycytidine could be exploited to modulate antigen expression in combination with immunotherapeutic approaches. Prostate 67: 1781–1790, 2007. © 2007 Wiley‐Liss, Inc.
Theoretical studies of the spin Hamiltonian parameters for the tetragonal Co4+ and Ir4+ centers in SrTiO3
Authors: Wu Shao‐Yi , Zhang Hua‐Ming , Lu Guang‐Duo , Zhang Zhi‐Hong , Wei Li‐Hua
Published: October 2007

The spin Hamiltonian parameters, g factors and the hyperfine structure constants for Co4+ (3d5) and Ir4+ (5d5) in SrTiO3 are theoretically studied from the formulas of these parameters for an n d5 (n = 3 and 5) ion in a tetragonally distorted octahedron with low spin S = 1/2. According to the theoretical analyses, the impurity–ligand bond lengths R ′‖ parallel to the C4 axis are found to be larger than the host values R‖ based on the phase transition rotation angles ϕ of the [TiO6]8– octahedron by the C4 axis at 4.2 and 77 K, respectively. The elongation of the ligand octahedra in the host may be enhanced in the impurity centers by the Jahn–Teller effect of the n d5 ions. The theoretical results based on the above local structures show good agreement with the experimental data. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Anomalous refraction of backward waves in ferromagnet–semiconductor superlattices in the presence of an external magnetic field
Authors: Tarkhanyan Roland H. , Niarchos Dimitris G.
Published: October 2007

Features of anomalous refraction of electromagnetic waves in a semiconductor–ferromagnet superlattice are investigated in the presence of an external magnetic field which is parallel to the optical axis of the superlattice. Effective permittivity and permeability tensors are obtained using the method of anisotropic homogeneous medium. General conditions are found at which the structure behaves as a left‐handed negative‐index metamaterial. Field structure of the waves is found and frequency regions are studied at which the medium is described by negative group refractive index. It is shown that main properties of the refracted waves, in particular, the number of the backward bulk modes and the width of the frequency regions with anomalous refraction can be changed using the external magnetic field as tuning parameter. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis of optical spectra of V2+ centres in ZnS and ZnSe single crystals
Authors: Brik M. G. , Kityk I. V.
Published: October 2007

A systematic spectroscopic study of V2+‐doped ZnS and ZnSe single crystals (which includes crystal growth, absorption spectra measurements and combined application of the crystal field calculations and first‐principles analysis of V2+ energy levels and absorption spectra) is reported. Detailed comparison between the calculated energy levels and experimental absorption spectra enabled the assignment of the absorption peaks. The dependence of the crystal field and covalent effects on the interionic distance is analysed qualitatively. Several existing discrepancies between various literature data concerning the order of the V2+ energy levels (in particular, the positions of the 2E and 4T1 (4P) levels) are resolved. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electromagnetic fields induced by a concentrated heat source in multiferroic materials
Authors: Wang X. , Pan E. , Feng W. J. , Albrecht J. D.
Published: October 2007

Pyroelectric and pyromagnetic effects are important for applications of multiferroic materials in elevated temperature environments. In this paper, we derive exact closed‐form electromagnetic Green's function expressions for polarization fields in uniaxial multiferroic materials and bimaterials induced by a steady point heat source. The pyroelectric and pyromagnetic effects as a result of temperature change in multiferroic materials are incorporated in this study. The degen‐ erate and nondegenerate cases, which pertain to whether the heat conduction characteristic constant is equal to one of the two electromagnetic characteristic constants, are discussed in detail. The Green's functions for a bimaterial composed of two perfectly bonded uniaxial multiferroic half‐spaces subjected to a point heat source are further obtained by means of the image method. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of electric and magnetic fields on the binding energy of a Coulomb impurity bound polaron in a cylindrical quantum dot
Authors: Vartanian Arshak L. , Vardanyan Lyudvig A. , Kazaryan Eduard M.
Published: October 2007

The influence of electric and magnetic fields as well as electron‐polar optical phonon interaction on an electron bound to a Coulomb impurity in a cylindrical quantum dot is studied theoretically. The interplay between the confinement effects due to applied fields, quantum‐size confinements, and the electron–phonon coupling on the impurity binding energy is analyzed. Analytical expression for polaron energy has been obtained as a function of the QD sizes, intensities of the electric and magnetic fields and the position of the impurity in the QD. It is found that the corrections on impurity binding energy due to the LO phonons are very important and cannot be neglected. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Significance of charge‐dipolar moiety interaction: Computational study of cyanospherands
Authors: Elroby Shabaan A. K. , Hwan Lee Kyu , Joo Cho Seung
Published: October 2007

Cyanospherands (CN‐spherands) are highly preorganized hosts which bind cations. Density functional theory calculations were used to investigate the complexation between cyanospherands and alkali metal ions (Li+, Na+, and K+). CN8‐spherand undergoes significant shape change upon complexation, i.e., the oval free host becomes spherical when complexed with cations. All cationic guests prefer external binding to encapsulation in spite of spherically well organized charged moieties and the spacious cavity of hosts. The ion‐dipolar moiety interaction has been found to be a decisive factor for the preference for external binding. This demonstrates the importance of ion‐dipolar moiety orientations as well as the host‐guest size complementarity, to design novel ionophores. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Dietary exposure and trends of exposure to nutrient elements iodine, iron, selenium and sodium from the 2003–4 New Zealand Total Diet Survey
Authors: Thomson Barbara M. , Vannoort Richard W. , Haslemore Roger M.
Published: October 2007

The mean dietary exposure to the nutrient elements iodine, Fe, Se and Na by eight age–sex groups of the New Zealand population was estimated from foods purchased and prepared as for consumption. A total of 968 samples comprising 121 foods were collected and analysed. Mean daily exposures were calculated from mean concentration levels of the selected nutrients in each food combined with simulated diets for a 25+-year-old male and female, a 19–24-year-old male, a 11–14-year-old boy and girl, a 5–6-year-old child, a 1–3-year-old toddler and a 6–12-month-old infant. Food concentrations and dietary exposures are reported and compared with nutrient reference values (for example, recommended daily intakes, adequate intakes or upper limits). Dietary iodine exposures for all age–sex groups were well below recommended levels and have steadily decreased since 1982, raising concern especially for the physical and mental development of infants and young children. Fe exposures meet the recommended daily intake for the average male and 11–14 year olds but are only about half that recommended for adult females. Se exposure is about 20 % less than optimal for females. Na exposures, excluding discretionary salt, are above the acceptable exposure level for all age–sex groups, and exceed the upper intake limits for 25+-year-old males, 19–24-year-old young males, and 11–14-year-old boys and girls by up to 125 % for an average consumer.
Oligosaccharides from human milk influence growth-related characteristics of intestinally transformed and non-transformed intestinal cells
Authors: Kuntz Sabine , Rudloff Silvia , Kunz Clemens
Published: October 2007

Human milk oligosaccharides (HMO) are considered to influence the composition of the gut microflora in breastfed infants. We investigated direct effects of milk HMO fractions or individual oligosaccharides on proliferation, differentiation and apoptosis in transformed human intestinal cells (HT-29 and Caco-2) and non-transformed small intestinal epithelial crypt cells of fetal origin (human intestinal epithelial cells; HIEC). We observed growth inhibition induced by neutral and acidic HMO fractions in HT-29, Caco-2 and HIEC cells in a dose dependent manner. However, the effects varied between cell lines, i.e. HT-29 and Caco-2 cells were more sensitive than HIEC cells. In HT-29, all 16 individual neutral and acidic oligosaccharides except from the two fucosyllactoses had an inhibitory effect on cell growth. Regarding the induction of differentiation in HT-29 and HIEC cells a threshold concentration was observed at 7·5 mg/ml for neutral and acidic HMO fractions. Among individual oligosaccharides, only sialyllactoses induced differentiation in HT-29 and HIEC cells; no effect neither of fractions nor of individual oligosaccharides was found in Caco-2 cells. A strong induction of apoptosis was only detected in HT-29 and HIEC cells for neutral oligosaccharide but not for acidic fractions. HMO were shown to induce growth inhibition in intestinal cells through two different mechanisms, by suppressing cell cycle progression through induction of differentiation and/or by influencing apoptosis. As the development and maturation of digestive and absorptive processes depend on differentiation our experiments show that oligosaccharides are effective at influencing various stages in gastrointestinal developmentin vitro.
Energy intake and resting energy expenditure in adult male rats after early postnatal food restriction
Authors: Remmers Floor , Schreuder Michiel F. , Gemke Reinoud J. B. J. , Delemarre-van de Waal Henriette A.
Published: October 2007

Both in man and in animal models, changes in food intake and body composition in later life have been reported after alterations in perinatal nutrition. Therefore, we hypothesised that early postnatal undernutrition in the rat induces permanent changes in energy balance. Food restriction (FR) during lactation was achieved by enlarging litter size to twenty pups, whereas control animals were raised in litters containing ten pups. Energy intake and resting energy expenditure were determined in adult males. Early postnatal FR resulted in acute growth restriction followed by incomplete catch-up in body weight, body length and BMI. At the age of 12 months, middle-aged FR males had significantly lower absolute resting energy expenditure (200 v. 216 kJ/24 h, P = 0·009), absolute energy intake (281 v. 310 kJ/24 h, P = 0·001) and energy intake adjusted for BMI (284 v. 305 kJ/24 h, P = 0·016) than controls, whereas resting energy expenditure adjusted for BMI did not differ significantly between the groups (204 v. 211 kJ/24 h, P = 0·156). The amount of energy remaining for other functions was lower in FR males (80 v. 94 kJ/24 h, P = 0·044). Comparable data were obtained at the age of 6 months. These results indicate that in rats energy balance can be programmed by early nutrition. A low early postnatal food intake appears to programme these animals for a low energy intake and to remain slender in adult life.
Neoadjuvant docetaxel and cisplatin chemotherapy followed by local irradiation is highly active on locoregionally advanced squamous cell carcinoma of the head and neck
Authors: Shin H-J , Chung J S , Choi Y J , Lee B J , Wang S G , Kim D W , Cho G J
Published: October 2007

The purpose of this study was to determine the treatment outcome of neoadjuvant docetaxel and cisplatin chemotherapy followed by local radiotherapy for chemotherapy-naïve patients with locoregionally advanced squamous cell carcinoma of the head and neck. Thirty-seven patients with stage III or IV squamous cell carcinoma of the head and neck who received docetaxel and cisplatin regimen for a maximum of three cycles followed by radiation therapy were enrolled in this study. The overall response rate to the regimen was 91.9 per cent (34 of 37) (the complete remission rate was 48.6 per cent). The median time to treatment failure was 38 months (95 per cent confidence interval, 15–61 months). The four year estimated overall survival rates were 85.1 per cent. The most frequent moderate-to-severe toxicity was grade 3–4 neutropenia. The most common acute non-haematologic toxicities included anorexia, nausea and asthenia. Neoadjuvant docetaxel and cisplatin chemotherapy followed by radiotherapy is a feasible treatment strategy for patients with locoregionally advanced squamous cell carcinoma of the head and neck.
Simple Doppler Wind Lidar adaptive observation experiments with 3D‐Var and an ensemble Kalman filter in a global primitive equations model
Authors: Liu Junjie , Kalnay Eugenia
Published: October 2007

Through simple Observing System Simulation Experiments, we compare several adaptive observation strategies designed to subsample Doppler Wind Lidar (DWL) observations along satellite tracks, and examine the effectiveness of two data assimilation schemes, 3D‐Var and the Local Ensemble Transform Kalman Filter (LETKF). With respect to sampling strategies, our results show that the LETKF‐based ensemble spread method is superior to the other strategies tested, namely, use of a uniform distribution, the climatological spread strategy, or use of a random distribution, and is close to the ideal result obtained assuming that the true forecast error is known. With 10% DWL observations from the ensemble spread strategy, both 3D‐Var and LETKF attain about 90% of the impact that 100% DWL wind profile coverage would provide. However, when the adaptive DWL observations coverage is reduced to 2%, 3D‐Var becomes less effective than the LETKF assimilation scheme.
Diverse responses of vegetation phenology to a warming climate
Authors: Zhang Xiaoyang , Tarpley Dan , Sullivan Jerry T.
Published: October 2007

Warming climates have been widely recognized to advance spring vegetation phenology. However, the delayed responses of vegetation phenology to rising temperature and their mechanisms are poorly understood. Using satellite and climate data from 1982 to 2005, we reveal a latitude transition zone of greenup onset in vegetation communities that has diversely responded to warming temperature in North America. From 40°N northwards, a winter chilling requirement for vegetation dormancy release is far exceeded and the decrease in chilling days by warming winter temperature has little impact on thermal‐time requirements for greenup onset. Thus, warming spring temperature has constantly advanced greenup onset by 0.32 days/year. However, from 40°N southward, the shortened winter chilling days are insufficient for fulfilling vegetation chilling requirement, so that the thermal‐time requirement for greenup onset during spring increases gradually. Consequently, vegetation greenup onset changes progressively from an early trend (north region) to a later trend (south region) along the latitude transition zone from 40–31°N, where the switch occurs around 35°N. The greenup onset is delayed by 0.15 days/year below 31°N.
A microphysical model for strong velocity weakening in phyllosilicate‐bearing fault gouges
Authors: Niemeijer A. R. , Spiers C. J.
Published: October 2007

Previous rotary shear experiments, performed on a halite‐muscovite fault gouge analogue system have shown that the presence of phyllosilicates, under conditions favoring the operation of cataclasis and pressure solution in the matrix phase, can have major effects on the frictional behavior of gouges. While 100% halite and 100% muscovite samples exhibit rate‐independent frictional/brittle behavior, the strength of mixtures containing 10–30% muscovite is both normal stress and sliding velocity‐dependent. At high sliding velocities (>1 μm s−1), such mixtures show unusually marked velocity weakening, along with the development of a structureless, cataclastic microstructure. In the present paper, a micromechanical model is developed in an attempt to explain this behavior. The model assumes a granular flow process involving competition between intergranular dilatation and compaction by pressure solution. The predictions of the model agree favorably with the experimental results. Extension of the model to quartz‐mica systems implies that the presence of phyllosilicates plus the operation of pressure solution can strongly promote (unstable) velocity‐weakening behavior at rapid slip rates on natural faults, under midcrustal conditions. Static stress drop predictions based on the model agree reasonably well with estimates from seismic observations. Our results may help explain the discrepancy between laboratory‐derived rate‐and‐state friction parameter values, obtained for dry, low‐strain and/or single‐phase rock systems, and the values for natural fault rocks inferred from seismological data.
Comparison of Plasma Input and Reference Tissue Models for Analysing [11C]flumazenil Studies
Authors: Klumpers Ursula MH , Veltman Dick J , Boellaard Ronald , Comans Emile F , Zuketto Cassandra , Yaqub Maqsood , Mourik Jurgen EM , Lubberink Mark , Hoogendijk Witte JG , Lammertsma Adriaan A
Published: October 2007

A single-tissue compartment model with plasma input is the established method for analysing [11C]flumazenil ([11C]FMZ) studies. However, arterial cannulation and measurement of metabolites are time-consuming. Therefore, a reference tissue approach is appealing, but this approach has not been fully validated for [11C]FMZ. Dynamic [11C]FMZ positron emission tomography scans with arterial blood sampling were performed in nine drug-free depressive patients and eight healthy subjects. Regions of interest were defined on co-registered magnetic resonance imaging scans and projected onto dynamic [11C]FMZ images. Using a Hill-type metabolite function, single (1T) and reversible two-tissue (2T) compartmental models were compared. Simplified reference tissue model (SRTM) and full reference tissue model (FRTM) were investigated using both pons and (centrum semiovale) white matter as reference tissue. The 2T model provided the best fit in 59% of cases. Two-tissue VT values were on average 1.6% higher than 1T VT values. Owing to the higher rejection rate of 2T fits (7.3%), the 1T model was selected as plasma input method of choice. SRTM was superior to FRTM, irrespective whether pons or white matter was used as reference tissue. BPND values obtained with SRTM correlated strongly with 1T VT ( r = 0.998 and 0.995 for pons and white matter, respectively). Use of white matter as reference tissue resulted in 5.5% rejected fits, primarily in areas with intermediate receptor density. No fits were rejected using pons as reference tissue. Pons produced 23% higher BPND values than white matter. In conclusion, for most clinical studies, SRTM with pons as reference tissue can be used for quantifying [11C]FMZ binding.
Nonlinear Marangoni convection in circular and elliptical cylinders
Authors: Assemat P. , Bergeon A. , Knobloch E.
Published: October 2007

The spatial organization of single-fluid Marangoni convection in vertical cylinders with circular or elliptical horizontal cross section is described. The convection is driven by an imposed heat flux from above through Marangoni stresses at a free but undeformed surface due to temperature-dependent surface tension. The solutions and their stability characteristics are obtained using branch-following techniques together with direct numerical simulations. The changes in the observed patterns with increasing ellipticity are emphasized. In some cases, the deformation of the cylinder results in the presence of oscillations.
Optical control of ground-state atomic orbital alignment: Cl(P3∕22) atoms from HCl(v=2,J=1) photodissociation
Authors: Sofikitis Dimitris , Rubio-Lago Luis , Martin Marion R. , Ankeny Brown Davida J. , Bartlett Nathaniel C.-M. , Alexander Andrew J. , Zare Richard N. , Rakitzis T. Peter
Published: October 2007

H Cl 35 ( v = 0 , J = 0 ) molecules in a supersonic expansion were excited to the HCl35(v=2,J=1,M=0) state with linearly polarized laser pulses at about 1.7μm. These rotationally aligned J=1 molecules were then selectively photodissociated with a linearly polarized laser pulse at 220nm after a time delay, and the velocity-dependent alignment of the Cl35(P3∕22) photofragments was measured using 2+1 REMPI and time-of-flight mass spectrometry. The Cl35(P3∕22) atoms are aligned by two mechanisms: (1) the time-dependent transfer of rotational polarization of the HCl35(v=2,J=1,M=0) molecule to the Cl35(P3∕22) nuclear spin [which is conserved during the photodissociation and thus contributes to the total Cl35(P3∕22) photofragment atomic polarization] and (2) the alignment of the Cl35(P3∕22) electronic polarization resulting from the photoexcitation and dissociation process. The total alignment of the Cl35(P3∕22) photofragments from these two mechanisms was found to vary as a function of time delay between the excitation and the photolysis laser pulses, in agreement with theoretical predictions. We show that the alignment of the ground-state Cl35(P3∕22) atoms, with respect to the photodissociation recoil direction, can be controlled optically. Potential applications include the study of alignment-dependent collision effects.
Electron and ion reactions with hexamethyldisiloxane and pentamethyldisiloxane
Authors: Carles S. , Le Garrec J. L. , Mitchell J. B. A.
Published: October 2007

The dissociative recombination of electrons with the hexamethyldisiloxane (HMDSO) cation ((CH3)3Si–O–Si(CH3)3)+ and the pentamethyldisiloxane cation ((CH3)3Si–O–Si(CH2)2)+ as well as the ion-molecule reaction between Ar+ and HMDSO have been studied at 300K using a flowing afterglow Langmuir probe-mass spectrometer apparatus. The rate constants for these reactions, measured directly for the first time, are, respectively, α1=1.8×10−6, α2=3.6×10−6cm3∕s, and k=2.0×10−9cm3∕s with uncertainties of ±30%. In addition, the electronic attachment to neutral HMDSO was also studied and an upper limit value of the rate constant was determined to be β=3.3×10−11cm3∕s.
Consistent free energy landscapes and thermodynamic properties of small proteins based on a single all-atom force field employing an implicit solvation
Authors: Kim Eunae , Jang Soonmin , Pak Youngshang
Published: October 2007

We have attempted to improve the PARAM99 force field in conjunction with the generalized Born (GB) solvation model with a surface area correction for more consistent protein folding simulations. For this purpose, using an extended α∕β training set of five well-studied molecules with various folds (α, β, and ββα), a previously modified version of PARAM99/GBSA is further refined, such that all native states of the five training species correspond to their lowest free energy minimum states. The resulting modified force field (PARAM99MOD5/GBSA) clearly produces reasonably acceptable conformational free energy surfaces of the training set with correct identifications of their native states in the free energy minimum states. Moreover, due to its well-balanced nature, this new force field is expected to describe secondary structure propensities of diverse folds in a more consistent manner. Remarkably, temperature dependent behaviors simulated with the current force field are in good agreement with the experiment. This agreement is a significant improvement over the existing standard all-atom force fields. In addition, fundamentally important thermodynamic quantities, such as folding enthalpy (ΔH) and entropy (ΔS), agree reasonably well with the experimental data.
Antenna excitation of drift wave in a toroidal plasma
Authors: Diallo A. , Ricci P. , Fasoli A. , Furno I. , Labit B. , Müller S. H. , Podestà M. , Poli F. M. , Skiff F.
Published: October 2007

In a magnetized toroidal plasma, an antenna tunable in vertical wave number is used to excite density perturbations. Coherent detection is performed by means of Langmuir probes to directly determine both the wave vector and the plasma response induced by the antenna. Comparison between the theoretical density response predicted by the generalized Hasegawa-Wakatani model, and the experimentally determined density response enables us the identification of one peak of the plasma response as a drift wave.
Evidence of pseudocubic structure in sol-gel derived Pb1−xCaxTiO3 (x=0.35–0.48) ceramic by dielectric and Raman spectroscopy
Authors: Singh Arun , Sreenivas K. , Katiyar R. S. , Gupta Vinay
Published: October 2007

Calcium doped lead titanate (Pb1−xCaxTiO3) ceramics with varying stoichiometry (x=0–0.55) have been prepared using sol-gel derived powder. The x-ray diffraction shows the transformation of crystallographic structure from tetragonal to cubic at x∼0.35. Raman spectroscopy and temperature dependent dielectric studies were made on all prepared ceramic samples. A continuous shift in the phase transition temperature toward lower temperature was observed with increase in x. The presence of soft phonon mode in the Raman spectra, along with phase transition temperature, gives the evidence for the formation of pseudocubic structure of Pb1−xCaxTiO3 ceramics for higher values of x>0.35.
Spectroscopic characterization of the electrical properties of Fe implants on GaInP∕GaAs
Authors: Fraboni Beatrice , Castaldini A. , Cesca Tiziana , Gasparotto Andrea , Tarricone Luciano
Published: October 2007

We have investigated the structural and electrical properties of GaInP∕GaAs epilayers implanted with Fe atoms to produce a shallow high resistivity layer. Proton-induced x-ray emission channeling measurements indicate that the substitutional fraction of the Fe implanted atoms decreases with increasing postimplant annealing temperatures. However, current-voltage analyses as a function of temperature indicate that a high temperature postimplantation annealing is necessary for the removal of the implantation-induced damage and for the activation of an efficient and stable electrical compensation process, which we have ascribed to the interplay between a deep donor and a deep acceptor, located at EC−0.50eV and EV+0.74eV, respectively. We have focused our attention on the latter deep level, attributed to the Fe2+∕3+ related acceptor trap, which we have directly identified and characterized by spectral photocurrent analyses and by capacitance transient spectroscopy carried out under below-band-gap illumination, which stimulated the direct emission/trapping of carriers from the deep trap.
Magnetic memory of oil paintings
Authors: Costa Ribeiro P. , Bruno A. C. , Carvalho H. R. , Kafensztok S. M. , Almeida P. O. , Wolff C. S. , Lins de Barros H. , Acosta-Avalos D. , Symko O. G.
Published: October 2007

The color in oil paints is obtained sometimes from magnetic minerals. This fact implies that oil paintings could present an intrinsic magnetization. Magnetic imaging of an oil painting consists in the measurement of magnetic flux related to the magnetization of the painting. In this report results of magnetic measurements show that oil paints from different manufacturers (Maimeri, Pebeo, and Grumbacher) are magnetic. The magnetic imagings of four similar oil paintings done with the same visual color, obtained using different mixtures of oil paints for each painting, were different. This shows that the magnetic imaging can be used as a fingerprint for the oil paintings. Magnetic imaging was obtained for oil paintings done by Oswald, Bianco, and Timoteo, all of them are Brazilian painters. The imaging obtained in measurements at different times was always the same, showing that the magnetic images are stable. This leads to the conclusion that magnetic imaging would be a common authentication technique of paintings.
Bi-invariant and noninvariant metrics on Lie groups
Authors: Ghanam R. , Hindeleh F. , Thompson G.
Published: October 2007

A restricted version of the inverse problem of Lagrangian dynamics for the canonical linear connection on a Lie group is studied. Specifically for solvable Lie algebras of dimension up to and including six all algebras for which there is a compatible pseudo-Riemannian metric on the corresponding linear Lie group are found. Of the 19 such metrics four are bi-invariant. The Lie algebras are taken from tables compiled originally by Mubarakzyanov [Izv. Vyssh. Uchebn. Zaved., Mat. 4, 104–116 (1963)] and Morozov [Izv. Vyssh. Uchebn. Zaved., Mat. 4, 161–171 (1958)].
Spin-polarized current versus stray field in a perpendicularly magnetized superconducting spin switch
Authors: Singh A. , Sürgers C. , Hoffmann R. , Löhneysen H. v. , Ashworth T. V. , Pilet N. , Hug H. J.
Published: October 2007

In superconducting Co∕Pt–Nb–Co∕Pt multilayers with perpendicular magnetic anisotropy, the superconducting transition temperature Tc is considerably higher in the parallel (P) orientation of the two Co∕Pt magnetizations compared to the antiparallel (AP) orientation. Low temperature magnetic-force microscopy reveals that the individual ferromagnetic layers are uniformly magnetized in both configurations and do not exhibit a magnetic stray field arising from a multidomain state. We also demonstrate that the difference ΔTc=TcP−TcAP between both Tc values is enhanced at higher transport currents due to the increasing imbalance of spin-polarized charge carriers in the superconducting Nb layer. Hence, the spin switch can be controlled by the transport current in future superconducting devices.
The origin of deficiency of the supermolecule second-order Møller-Plesset approach for evaluating interaction energies
Authors: Cybulski Slawomir M. , Lytle Marion L.
Published: October 2007

Calculations for the complex of thymine and adenine are used to show that the supermolecule second-order Møller-Plesset perturbation theory (MP2) approach for evaluating interaction energies fails in certain cases because of the behavior of one of its components: the uncoupled Hartree-Fock dispersion energy. A simple approach for correcting the MP2 supermolecule interaction energies is proposed. It focuses on correcting a relatively small difference between the MP2 and coupled cluster interaction energies, which is a very appealing feature of the new approach considering a benchmark role played by coupled cluster results.
Intracule functional models. II. Analytically integrable kernels
Authors: Crittenden Deborah L. , Dumont Elise E. , Gill Peter M. W.
Published: October 2007

We present, within the framework of intracule functional theory (IFT), a class of kernels whose correlation integrals can be found in closed form. This approach affords three major advantages over other kernels that we have considered previously; ease of implementation, computational efficiency, and numerical stability. We show that even the simplest member of the class yields reasonable estimates of the correlation energies of 18 atomic and 56 molecular systems and we conclude that this kernel class will prove useful in the development of future IFT models.
Improved electrical properties of metal-oxide-semiconductor capacitor with HfTiON gate dielectric by using HfSiON interlayer
Authors: Xu J. P. , Ji F. , Li C. X. , Lai P. T. , Guan J. G. , Liu Y. R.
Published: October 2007

Metal-oxide-semiconductor (MOS) capacitor with HfTiON∕HfSiON stack structure as high-k gate dielectric is fabricated, and its electrical properties are compared with those of a similar device with HfTiON only as gate dielectric. Experimental results show that the device with HfTiON∕HfSiON gate dielectric exhibits better interface properties, lower gate leakage current, and enhanced high-field reliability. All these improvements should be attributed to the fact that the HfSiON buffer layer effectively blocks the diffusion of Ti atoms to the Si substrate, thus resulting in a SiO2∕Si-like HfSiON∕Si interface.
Characterization of nanostructures during growth using a quartz monitor
Authors: Phillips A. B. , Shivaram B. S.
Published: October 2007

The quartz thickness monitor, a high Q mechanical device, is ubiquitous in thin film deposition applications. It provides information that is one dimensional—the average thickness of the film. In this letter, we describe a method where a related device, a surface acoustic wave resonator, employed as a gravimetric sensor has been used to ascertain the radius of freestanding spherical nanoparticles. Direct measurements of particle size through scanning electron microscopy confirm the validity of this method. Its success implies that use of high Q mechanical oscillators can be extended to extract the lateral extent of nanostructures during growth.
Magnetic field dependent behavior in perpendicular antiferromagnetically coupled multilayer films
Authors: Fu Y. , Pei W. , Yuan J. , Wang T. , Hasegawa T. , Washiya T. , Saito H. , Ishio S.
Published: October 2007

Magnetization reversal and magnetic domain structures controlled by the magnetostatically induced stray field in perpendicular antiferromagnetically coupled [Pd∕Co]7∕Ru∕Co∕[Pd∕Co]7 multilayer were investigated by magnetic force microscopy. For the sample demagnetized in plane, field-induced ferromagnetic domains at the boundary of antiferromagnetic domains provide the nucleation channel. The ferromagnetic domains in the channel are parallel aligned along the applied field out of plane firstly, and then the magnetization reversal is dominated by the propagation of the ferromagnetic channels toward the region of antiferromagnetic domains. The sample demagnetized in perpendicular direction shows antiferromagnetic coupling state. Ultraslow reversal dynamics were observed under a perpendicular critical magnetic field (Hcri) in a long time. The reversal process can be explained by the inhomogeneous local stray field and the competition between magnetostatic energy and exchange energy.
Structure and magnetism in VO2 nanorods
Authors: Park Jitae , Oh In Hwan , Lee Eunmo , Lee Kyu Won , Lee Cheol Eui , Song Kyung , Kim Youn-Joong
Published: October 2007

The structural and magnetic properties in vanadium dioxide (VO2) nanorods prepared by the hydrothermal treatment are shown to be markedly different from the case of the bulk system. A peculiar mixed phase of an insulating monoclinic structure (M2) that is observed in the bulk systems under doping or stress and a rutile (R) structure was revealed and confirmed by transmission electron microscopy, x-ray diffraction, and electron spin resonance measurements. Besides, a broad transition from a high-temperature magnetic phase to a low-temperature one, with quite distinct magnetic correlation strengths, was observed.
Band engineering in Al0.5Ga0.5N∕GaN superlattice by modulating Mg dopant
Authors: Li Jinchai , Kang Junyong
Published: October 2007

The electronic structures of Mg modulation-doped and undoped Al0.5Ga0.5N∕GaN superlattices (SLs) are investigated by using first-principles density function theory. The layer-projected densities of states indicate that the band alignment is changed from type I to type II and the band bending due to polarization is reduced significantly by modulating Mg dopant in AlGaN layer. It is further confirmed by the calculations of the partial charge density profiles and the valence band offsets where the valence-band maximum of AlGaN in Mg modulation-doped SL is located above that of GaN. The strong hybridization between N and Mg orbitals plays an important role on the upward shifts of the valence band edges.
Controllable modification of transport properties of single-walled carbon nanotube field effect transistors with in situ Al decoration
Authors: Kim Hyo-Suk , Kim Byoung-Kye , Kim Ju-Jin , Lee Jeong-O , Park Noejung
Published: October 2007

We use an in situ Al decoration technique to control the transport characteristics of single-walled carbon nanotube field effect transistors (SWNT-FETs). Al nanoparticle decoration in a high vacuum caused the devices to change from p-type to n-type FETs, and subsequent exposure to the ambient atmosphere induced a gradual recovery of p-type character. In comparison with the bare SWNT-FETs under high vacuum, the channel-open devices with decorated Al particles exhibited reduced current under ambient conditions. However, selective Al decoration only at the contact resulted in an improved p-type current in ambient air.
Expression of flagella is coincident with uropathogenic
Escherichia coli
ascension to the upper urinary tract
Authors: Lane M. Chelsea , Alteri Christopher J. , Smith Sara N. , Mobley Harry L. T.
Published: October 2007

Uropathogenic
Escherichia coli
(UPEC) cause most uncomplicated urinary tract infections (UTIs) in humans. Because UTIs are considered to occur in an ascending manner, flagellum-mediated motility has been suggested to contribute to virulence by enabling UPEC to disseminate to the upper urinary tract. Previous studies from our laboratory and others have demonstrated a modest yet important role for flagella during ascending UTI. To better understand the role of flagella
in vivo
, we used biophotonic imaging to monitor UPEC infection and temporospatial flagellin gene expression during ascending UTI. Using
em7-lux
(constitutive) and
fliC-lux
transcriptional fusions, we show that flagellin expression by UPEC coincides with ascension of the ureters and colonization of the kidney. The patterns of
fliC
luminescence observed
in vitro
and
in vivo
were also validated by comparative quantitative PCR. Because
fliC
expression appeared coincident during ascension, we reassessed the contribution of
fliC
to ascending UTI using a low-dose intraurethral model of ascending UTI. Although wild-type UPEC were able to establish infection in the bladder and kidneys by 6 hours postinoculation,
fliC
mutant bacteria were able to colonize the bladder but were significantly attenuated in the kidneys at this early time point. By 48 hours postinoculation, the
fliC
mutant bacteria were attenuated in the bladder and kidneys and were not detectable in the spleen. These data provide compelling evidence that wild-type UPEC express flagellin and presumably utilize flagellum-mediated motility during UTI to ascend to the upper urinary tract and disseminate within the host.
Hierarchies, multiple energy barriers, and robustness govern the fracture mechanics of α-helical and β-sheet protein domains
Authors: Ackbarow Theodor , Chen Xuefeng , Keten Sinan , Buehler Markus J.
Published: October 2007

The fundamental fracture mechanisms of biological protein materials remain largely unknown, in part, because of a lack of understanding of how individual protein building blocks respond to mechanical load. For instance, it remains controversial whether the free energy landscape of the unfolding behavior of proteins consists of multiple, discrete transition states or the location of the transition state changes continuously with the pulling velocity. This lack in understanding has thus far prevented us from developing predictive strength models of protein materials. Here, we report direct atomistic simulation that over four orders of magnitude in time scales of the unfolding behavior of α-helical (AH) and β-sheet (BS) domains, the key building blocks of hair, hoof, and wool as well as spider silk, amyloids, and titin. We find that two discrete transition states corresponding to two fracture mechanisms exist. Whereas the unfolding mechanism at fast pulling rates is sequential rupture of individual hydrogen bonds (HBs), unfolding at slow pulling rates proceeds by simultaneous rupture of several HBs. We derive the hierarchical Bell model, a theory that explicitly considers the hierarchical architecture of proteins, providing a rigorous structure–property relationship. We exemplify our model in a study of AHs, and show that 3–4 parallel HBs per turn are favorable in light of the protein's mechanical and thermodynamical stability, in agreement with experimental findings that AHs feature 3.6 HBs per turn. Our results provide evidence that the molecular structure of AHs maximizes its robustness at minimal use of building materials.
Centrally released oxytocin mediates mating-induced anxiolysis in male rats
Authors: Waldherr Martin , Neumann Inga D.
Published: October 2007

Sexual activity and mating are accompanied by a high level of arousal, whereas anecdotal and experimental evidence demonstrate that sedation and calmness are common phenomena in the postcoital period in humans. These remarkable behavioral consequences of sexual activity contribute to a general feeling of well being, but underlying neurobiological mechanisms are largely unknown. Here, we demonstrate that sexual activity and mating with a receptive female reduce the level of anxiety and increase risk-taking behavior in male rats for several hours. The neuropeptide oxytocin has been shown to exert multiple functions in male and female reproduction, and to play a key role in the regulation of emotionality after its peripheral and central release, respectively. In the present study, we reveal that oxytocin is released within the brain, specifically within the hypothalamic paraventricular nucleus, of male rats during mating with a receptive female. Furthermore, blockade of the activated brain oxytocin system by central administration of an oxytocin receptor antagonist immediately after mating prevents the anxiolytic effect of mating, while having no effect in nonmated males. These findings provide direct evidence for an essential role of an activated brain oxytocin system mediating the anxiolytic effect of mating in males.
Unusual lattice dynamics of vanadium under high pressure
Authors: Luo Wei , Ahuja Rajeev , Ding Yang , Mao Ho-kwang
Published: October 2007

The electronic structures and lattice dynamics of pressure-induced complex phase transitions [bcc →
h
R1(110.5°) → distorted-
h
R1(108.2°) → bcc] in vanadium as a function of pressure up to 400 GPa have been investigated with an
ab initio
method using density functional perturbation theory (DFPT). At ambient pressure, the soft transverse acoustic phonon mode corresponding to Kohn anomaly appears at a wave vector
q
= 2
k
F
along [ξ00] Γ → H high symmetry direction. The nondegenerate transverse acoustic branches TA
1
on 〈1̄10〉 and TA
2
on 〈001〉 show an exceptionally large split at high symmetry point
N
(0.5 0.5 0.0). The lattice dynamical instability starts at a pressure of 62 GPa (
V
/
V
0
= 0.78, where
V
0
is experimental volume of bcc-V at ambient conditions), derived by phonon softening that results in phase transition of bcc →
h
R1 (alpha = 110.5°). At compression around 130 GPa (
V
/
V
0
= 0.67), the rhombohedral angle of
h
R1 phase changed to 108.2°, and the electronic structure changed drastically. At even higher pressure, ≈250 GPa (
V
/
V
0
= 0.57), lattice dynamic calculations show that the bcc structure becomes stable again.
A small-molecule therapeutic lead for Huntington's disease: Preclinical pharmacology and efficacy of C2-8 in the R6/2 transgenic mouse
Authors: Chopra Vanita , Fox Jonathan H. , Lieberman Greg , Dorsey Kathryn , Matson Wayne , Waldmeier Peter , Housman David E. , Kazantsev Aleksey , Young Anne B. , Hersch Steven
Published: October 2007

Huntington's disease (HD) is a progressive neurodegenerative disease caused by a glutamine expansion within huntingtin protein. The exact pathological mechanisms determining disease onset and progression remain unclear. However, aggregates of insoluble mutant huntingtin (mhtt), a hallmark of HD, are readily detected within neurons in HD brain. Although aggregated polyglutamines may not be inherently toxic, they constitute a biomarker for mutant huntingtin useful for developing therapeutics. We previously reported that the small molecule, C2-8, inhibits polyglutamine aggregation in cell culture and brain slices and rescues degeneration of photoreceptors in a
Drosophila
model of HD. In this study, we assessed the therapeutic potential of C2-8 in the R6/2 mouse model of HD, which has been used to provide proof-of-concept data in considering whether to advance therapies to human HD. We show that, at nontoxic doses, C2-8 penetrates the blood–brain barrier and is present in brain at a high concentration. C2-8-treated mice showed improved motor performance and reduced neuronal atrophy and had smaller huntingtin aggregates. There have been no prior drug-like, non-toxic, brain-penetrable aggregation inhibitors to arise from cell-based high-throughput screens for reducing huntingtin aggregation that is efficacious in preclinical
in vivo
models. C2-8 provides an essential tool to help elucidate mechanisms of neurodegeneration in HD and a therapeutic lead for further optimization and development.
A unique mechanism of β-blocker action: Carvedilol stimulates β-arrestin signaling
Authors: Wisler James W. , DeWire Scott M. , Whalen Erin J. , Violin Jonathan D. , Drake Matthew T. , Ahn Seungkirl , Shenoy Sudha K. , Lefkowitz Robert J.
Published: October 2007

For many years, β-adrenergic receptor antagonists (β-blockers or βAR antagonists) have provided significant morbidity and mortality benefits in patients who have sustained acute myocardial infarction. More recently, β-adrenergic receptor antagonists have been found to provide survival benefits in patients suffering from heart failure, although the efficacy of different β-blockers varies widely in this condition. One drug, carvedilol, a nonsubtype-selective βAR antagonist, has proven particularly effective in the treatment of heart failure, although the mechanism(s) responsible for this are controversial. Here, we report that among 16 clinically relevant βAR antagonists, carvedilol displays a unique profile of
in vitro
signaling characteristics. We observed that in β2 adrenergic receptor (β2AR)-expressing HEK-293 cells, carvedilol has inverse efficacy for stimulating G
s
-dependent adenylyl cyclase but, nonetheless, stimulates (
i
) phosphorylation of the receptor's cytoplasmic tail on previously documented G protein-coupled receptor kinase sites; (
ii
) recruitment of β-arrestin to the β2AR; (
iii
) receptor internalization; and (
iv
) activation of extracellular regulated kinase 1/2 (ERK 1/2), which is maintained in the G protein-uncoupled mutant β2AR
T68F,Y132G,Y219A
(β2AR
TYY
) and abolished by β-arrestin2 siRNA. Taken together, these data indicate that carvedilol is able to stabilize a receptor conformation which, although uncoupled from G
s
, is nonetheless able to stimulate β-arrestin-mediated signaling. We hypothesize that such signaling may contribute to the special efficacy of carvedilol in the treatment of heart failure and may serve as a prototype for a new generation of therapeutic β2AR ligands.