bluuebunny/crossref_metadata_2025 huggingface dataset:
Late Wisconsin Paleoecologic Record from Swamp Lake, Yosemite National Park, California
Authors: Smith Susan J. , Anderson R. Scott
Published: July 2006

A 7.86-m sediment core from Swamp Lake in Yosemite National Park, California, provides a continuous record of environmental change over the last ca. 16,000 yr, as inferred from pollen, macrofossil, and microscopic charcoal analyses. The core stratigraphy documents late Wisconsin (Tioga stage) deglaciation between >16,000 and 13,700 yr B.P., approximately 6000-3500 yr earlier than higher-elevation Sierra Nevada records. The core includes five volcanic ash layers, chemically identified as four Mono Craters ashes and the Tsoyawata ash (Mt. Mazama, Oregon). The fossil record shows that herbs and sagebrush dominated the glacial environment at Swamp Lake. By 12,000 yr B.P., a mixed conifer forest composed of high- and mid-elevation conifers grew around the lake, suggesting a cool, wet late-glacial environment. The modern Sierra montane forest did not become established until ca. 10,400 yr B.P., when maximum charcoal concentrations and minimum fir pollen percentages indicate an early Holocene xeric period. The record suggests that a cooling trend began ca. 6500 yr B.P. and persisted until ca. 3700 yr B.P. when the modern climatic regime was established.
Policy Tools and Institutional Change: Comparing education policies in Norway, Sweden and England
Authors: HELGØY INGRID , HOMME ANNE
Published: July 2006

The main question raised in this article is how educational reforms reflect convergence or divergence between the English, the Norwegian and the Swedish educational systems. We claim that the answer depends on how convergence is conceptualised. At the level of decisions on tools, the countries seem more similar than two decades ago. However, to explain policy changes our analytical perspective must be broadened. We demonstrate how values based on different welfare state models, political economies and different types of institutional evolution can explain processes of change in education over the last decades. In paying attention to broader processes of change, a certain degree of variation occurs. The countries seem to develop according to nationally specific trajectories: England has strengthened the liberal and elitist values of education while social democratic values of comprehensiveness and equality have impact on the aims and effects of policy tools in Norway and Sweden.
Product Placement, Markengedächtnis, Markenimage (1)
Authors: Bock Michael , Gómez Izquierdo Siracusa
Published: July 2006

Zusammenfassung. Nach den Ergebnissen bisheriger Untersuchungen ist unklar, inwieweit es sich bei dem Product Placement um eine effektive Werbemethode handelt. In einer eigenen Untersuchung mit zwei James-Bond-Filmen haben wir deshalb überprüft, inwieweit diese Methode geeignet ist, das implizite und explizite Markengedächtnis und das Markenimage zu verbessern. Bei der Messung des impliziten Gedächtnisses wurden Markenfragmente und Produktkategorien dargeboten, zu denen spontan beliebige Wörter assoziiert werden sollten. Bei der Messung des expliziten Gedächtnisses sollten die platzierten Marken erinnert werden, und zwar ebenfalls mit Hilfe der Fragmente und Produktkategorien. Außerdem wurde ein Rekognitionstest durchgeführt. Das Markenimage wurde auf fünf verschiedenen Einstufungsskalen gemessen. Insgesamt blieb das Product Placement jedoch weitgehend wirkungslos: Es verbesserte weder die impliziten Markenerinnerungen noch das Markenimage, und die expliziten Markenerinnerungen nur wenig.
Results from a three‐dimensional, nested biological‐physical model of the California Current System and comparisons with statistics from satellite imagery
Authors: Powell Thomas M. , Lewis Craig V. W. , Curchitser Enrique N. , Haidvogel Dale B. , Hermann Albert J. , Dobbins Elizabeth L.
Published: July 2006

A three‐dimensional model of the California Current System (CCS) from 35°N to 48°N extending offshore to 134°W is coupled with a four‐component trophic model. The model reproduces many conspicuous characteristics in the CCS, including: complex, filamentary, mesoscale surface features seen in the pigment and temperature from satellite imagery; wind‐driven coastal upwelling at appropriate spatial and temporal scales; and the close correlation between prominent features seen in pigment and those in temperature observed by satellites (Abbott and Zion, 1985). Statistical estimates of the characteristic spatial scales of variability, as calculated from the coupled, nested model, agree with those previously estimated from satellite images (for both surface temperature and pigment (Denman and Abbott, 1988, 1994)). Model estimates of the characteristic temporal scales of variability, from decorrelation times, agree with those previously estimated from satellite images. Typical model decorrelation times lie between 2 and 4 days, in agreement with calculations from earlier sequences of (Coastal Zone Color Scanner (CZCS) and advanced very high resolution radiometer (AVHRR)) satellite images (Denman and Abbott, 1988, 1994).
Intercomparison of GOME, ozonesonde, and SAGE II measurements of ozone: Demonstration of the need to homogenize available ozonesonde data sets
Authors: Liu Xiong , Chance Kelly , Sioris Christopher E. , Kurosu Thomas P. , Newchurch Michael J.
Published: July 2006

We investigate the large systematic biases, especially in the stratosphere, between ozone profiles retrieved from the Global Ozone Monitoring Experiment (GOME) and ozonesonde observations at some ozonesonde stations. GOME retrievals are intercompared with both ozonesonde data at 33 stations between 75°N and 71°S and Stratospheric Aerosol and Gas Experiment II (SAGE II) data during 1996–1999. GOME stratospheric column ozone (SCO) over the altitude range ∼15–35 km usually agrees with SAGE II SCO to within 2.5 DU (1.5%, 1 DU = 2.69 × 1016 molecules cm−2) without significant spatiotemporal dependence but is systematically larger than ozonesonde SCO by 8–20 DU (5–10%) over carbon iodine (i.e., an ozonesonde technique) stations and most stations within 30°N–30°S. Evaluation of GOME, SAGE II, TOMS, and Dobson data here demonstrates that those biases mainly originate from ozonesonde underestimates in the stratosphere. GOME retrievals also show large positive biases of 20–70% at carbon iodine stations (except for Syowa) and most stations within 30°N–30°S over ∼10–20 km, where ozone concentration is low, while the biases relative to SAGE II data over ∼15–20 km is usually 10–20%. The discrepancies over this altitude region reflect biases in GOME retrievals as well as ozonesonde measurements. In addition, GOME/sonde biases in both SCO and profiles (especially in the lower stratosphere and upper troposphere) vary from station to station and depend on sonde technique, instrument type, sensor solution, and data processing, demonstrating the need to homogenize available ozonesonde data sets and standardize future operational procedures for reliable and consistent satellite validation.
Simulating heat transport of harmonic temperature signals in the Earth's shallow subsurface: Lower‐boundary sensitivities
Authors: Smerdon Jason E. , Stieglitz Marc
Published: July 2006

We assess the sensitivity of a subsurface thermodynamic model to the depth of its lower‐boundary condition. Analytic solutions to the one‐dimensional thermal diffusion equation demonstrate that boundary conditions imposed at shallow depths (2–20 m) corrupt the amplitudes and phases of propagating temperature signals. The presented solutions are for: 1) a homogeneous infinite half‐space driven by a harmonic surface‐temperature boundary condition, and 2) a homogeneous slab with a harmonic surface‐temperature boundary condition and zero‐flux lower‐boundary condition. Differences between the amplitudes and phases of the two solutions range from 0 to almost 100%, depending on depth, frequency and subsurface thermophysical properties. The implications of our results are straightforward: the corruption of subsurface temperatures can affect model assessments of soil microbial activity, vegetation changes, freeze‐thaw cycles, and hydrologic dynamics. It is uncertain, however, whether the reported effects will have large enough impacts on land‐atmosphere fluxes of water and energy to affect atmospheric simulations.
Anchoring and electro-optical dynamics of thin liquid crystalline films in a polyimide cell: Experiment and theory
Authors: Lee Lay Min , Kwon Hye J. , Kang Joo H. , Nuzzo Ralph G. , Schweizer Kenneth S.
Published: July 2006

The surface-dependent anchoring and electro-optical (EO) dynamics of thin liquid crystalline films have been examined using Fourier transform infrared spectroscopy. A simple nematic liquid crystal, 4-n-pentyl-4′-cyanobiphenyl (5CB), is confined as 40, 50, and 390nm thick films in nanocavities defined by gold interdigitated electrode arrays (IDEAs) patterned on polyimide-coated zinc selenide (ZnSe) substrates [Noble et al., J. Am. Chem. Soc. 124, 15020 (2002)]. New strategies for controlling the anchoring interactions and EO dynamics are explored based on coating a ZnSe surface with an organic polyimide layer in order to both planarize the substrate and induce a planar alignment of the liquid crystalline film. The polyimide layer can be further treated so as to induce a strong alignment of the nematic director along a direction parallel to the electrode digits of the IDEA. Step-scan time-resolved spectroscopy measurements were made to determine the rate constants for the electric-field-induced orientation and thermal relaxation of the 5CB films. In an alternate set of experiments, uncoated ZnSe substrates were polished unidirectionally to produce a grooved surface presenting nanometer-scale corrugations. The dynamical rate constants measured for several nanoscale film thicknesses and equilibrium organizations of the director in these planar alignments show marked sensitivities. The orientation rates are found to vary strongly with both the magnitude of the applied potential and the initial anisotropy of the alignment of the director within the IDEA. The relaxation rates do not vary in this same way. The marked variations seen in EO dynamics can be accounted for by a simple coarse-grained dynamical model.
The electronic structure of iron phthalocyanine probed by photoelectron and x-ray absorption spectroscopies and density functional theory calculations
Authors: Åhlund John , Nilson Katharina , Schiessling Joachim , Kjeldgaard Lisbeth , Berner Simon , Mårtensson Nils , Puglia Carla , Brena Barbara , Nyberg Mats , Luo Yi
Published: July 2006

A joint experimental and theoretical work to explain the electronic and geometrical structure of an in situ prepared film of iron phthalocyanine (FePc) on silicon (100) is presented. FePc molecular films have been characterized by core and valence photoemission spectroscopy (PES) and x-ray absorption spectroscopy (XAS), and the results have been interpreted and simulated by density functional theory (DFT) calculations. C1s and N1s PE spectra have been analyzed by taking into account all chemically nonequivalent C and N atoms in the molecule. In the Fe2p3∕2 spectra it has been possible to resolve two components that can be related to the open shell structure of the molecule. By valence PES and N1s XAS data, the geometrical orientation of the FePc molecules in the film could be determined. Our results indicate that for the FePc on Si(100), the molecules within the film are mainly standing on the surface. The experimental N1s XAS spectra are very well reproduced by the theoretical calculations, which are both angle and atomic resolved, giving a detailed description of the electronic and geometric structure of the FePc film. Furthermore, the asymmetry and the intensity angle variation of the first N1s XAS threshold feature could be explained by the presented DFT calculations as due to the chemical nonequivalence of the N atoms and the symmetry character of the lowest unoccupied molecular orbital.
The density profile of hard sphere liquid system under gravity
Authors: Chen Huanyang , Ma Hongru
Published: July 2006

The density profile of hard sphere liquid under gravity is calculated by using density functional theory and Monte Carlo simulation method. The two methods give consistent results for a wide range of parameters. Meanwhile, the validity range of the density functional theory is also established. The results are quite different from the barometric height distribution ρ(z)=ρ0exp(−z∕LG) in almost all cases studied, which indicates that the interaction between particles plays an important role in the density distribution under external fields. Moreover, the crystallizing phenomenon is also predicted at the bottom part of the system under strong gravitation.
Infrared spectra of the (H2O)n–SO2 complexes in argon matrices
Authors: Hirabayashi Shinichi , Ito Fumiyuki , Yamada Koichi M. T.
Published: July 2006

The infrared spectra of the (H2O)n–SO2 complexes trapped in argon matrices have been investigated using Fourier transform infrared spectroscopy. In addition to the 1:1 and 2:1 complexes, the first spectroscopic evidence for the 3:1 complex has been obtained from the spectra of the SO stretching and the OH stretching modes. The observed frequency shifts in the bonded OH stretching region indicate that the hydrogen bonds of the 2:1 and 3:1 complexes are strengthened compared to that of the 1:1 complex, which suggests the cyclic structure of the complexes.
Reversible measure-preserving integrators for non-Hamiltonian systems
Authors: Ezra Gregory S.
Published: July 2006

We present a systematic method for deriving reversible measure-preserving integrators for non-Hamiltonian systems such as the Nosé-Hoover thermostat and generalized Gaussian moment thermostat (GGMT). Our approach exploits the (non-Poisson) bracket structure underlying the thermostat equations of motion. Numerical implementation for the GGMT system shows that our algorithm accurately conserves the thermostat energy function. We also study position and momentum distribution functions obtained using our integrator.
Scanning tunneling spectroscopy simulations of poly(3-dodecylthiophene) chains adsorbed on highly oriented pyrolytic graphite
Authors: Dubois M. , Latil S. , Scifo L. , Grévin B. , Rubio Angel
Published: July 2006

We report on a hybrid scheme to perform efficient and accurate simulations of scanning tunneling spectroscopy (STS) of molecules weakly bonded to surfaces. Calculations are based on a tight binding (TB) technique, including a self-consistent calculation of the electronic structure of the molecule, to predict STS conductance spectra. The use of a local basis makes our model easily applicable to systems with several hundreds of atoms. We performed first-principles density-functional calculations to extract the geometrical and electronic properties of the system. In this way, we can include, in the TB scheme, the effects of structural relaxation upon adsorption on the electronic structure of the molecule. This approach is applied to the study of regioregular poly(3-dodecylthiophene) polymer chains adsorbed on highly oriented pyrolytic graphite. Results of spectroscopic calculations are discussed and compared with recently obtained experimental data.
Second and fourth Painlevé hierarchies and Jimbo-Miwa linear problems
Authors: Gordoa Pilar R. , Joshi Nalini , Pickering Andrew
Published: July 2006

The relations between the different linear problems for Painlevé equations is an intriguing open problem. Here we consider our previously given second and fourth Painlevé hierarchies [Publ. Res. Inst. Math. Sci. (Kyoto) 37, 327–347 (2001)], and show that they could alternatively have been derived using the linear problems of Jimbo and Miwa. That is, we give a gauge transformation of our linear problems for these two hierarchies which maps those of the second and fourth Painlevé equations themselves onto those of Jimbo and Miwa.
Nonstatistical effects in the dissociation of ethyl radical: Finding order in chaos
Authors: Bach Andreas , Hostettler Jonas M. , Chen Peter
Published: July 2006

How does one identify order in complex dynamical systems? A Born-Oppenheimer molecular dynamics simulation of the dissociation of ethyl radical, C2H5, produces an ensemble of classical trajectories which are decomposed in the time-frequency domain using wavelets. A time-dependent scalar metric, the normalized instantaneous orbital complexity, is constructed and shown to correlate not only to the more conventional Lyapunov exponents but also to the dissociation time for an individual trajectory. The analysis of the ensemble of trajectories confirms that the long-lived trajectories are associated with a low degree of ergodicity. While the analysis of molecular dissociation dynamics is the narrow focus of the present work, the method is more general for discovery and identification of ordered regimes within large sets of chaotic data.
Modulation of dust acoustic waves with a quantum correction
Authors: Misra Amar P. , Roy Chowdhury A.
Published: July 2006

The one-dimensional quantum hydrodynamic model is considered in the limit of low phase velocity (compared to the Fermi thermal velocities) as well as the limit of low frequency (compared to the particle-neutral collision frequency) to study the amplitude modulation of dust-acoustic waves in a three-species quantum dusty plasma. Using the standard reductive perturbation technique, a nonlinear Schrödinger equation containing the quantum effects is derived. The quantum mechanical effects containing the quantum diffraction and quantum statistics on the modulational instability are studied both analytically and numerically. It is found that quantum effects are to suppress the instability.
An analysis of the accuracy of an initial value representation surface hopping wave function in the interaction and asymptotic regions
Authors: Sergeev Alexey , Herman Michael F.
Published: July 2006

The behavior of an initial value representation surface hopping wave function is examined. Since this method is an initial value representation for the semiclassical solution of the time independent Schrödinger equation for nonadiabatic problems, it has computational advantages over the primitive surface hopping wave function. The primitive wave function has been shown to provide transition probabilities that accurately compare with quantum results for model problems. The analysis presented in this work shows that the multistate initial value representation surface hopping wave function should approach the primitive result in asymptotic regions and provide transition probabilities with the same level of accuracy for scattering problems as the primitive method.
The orbital precession around oblate spheroids
Authors: Montanus J. M. C.
Published: July 2006

An exact series will be given for the gravitational potential generated by an oblate gravitating source. To this end the corresponding Epstein-Hubbell type elliptic integral is evaluated. The procedure is based on the Legendre polynomial expansion method and on combinatorial techniques. The result is of interest for gravitational models based on the linearity of the gravitational potential. The series approximation for such potentials is of use for the analysis of orbital motions around a nonspherical source. It can be considered advantageous that the analysis is purely algebraic. Numerical approximations are not required. As an important example, the expression for the orbital precession will be derived for an object orbiting around an oblate homogeneous spheroid.
Gyrotropic guiding-center fluid theory for turbulent inhomogeneous magnetized plasma
Authors: Jasperse John R. , Basu Bamandas , Lund Eric J. , Bouhram Mehdi
Published: July 2006

In this paper, a new fluid theory is given in the guiding-center and gyrotropic approximation which is derivable from the Vlasov-Maxwell equations. The theory includes the effect of wave-particle interactions for the weakly turbulent, weakly inhomogeneous, nonuniformly magnetized plasma, and it is applicable to a variety of space and laboratory plasmas. It is assumed that the turbulence is random and electrostatic, and that the velocity-space Fokker-Planck operator can be used to calculate the correlation functions that describe the wave-particle interactions. Conservation laws are derived that relate the low-order velocity moments of the particle distributions to the turbulence. The theory is based on the work of Hubbard [Proc. R. Soc. London, Ser. A 260, 114 (1961)] and Ichimaru and Rosenbluth [Phys. Fluids 13, 2778 (1970)]. In the work presented here, the idea is proposed that the fluid equations can be solved (1) by using measurements of the turbulence to specify the electric-field fluctuations; and (2) by using measurements of the low-order velocity moments to specify the initial and boundary conditions.
Molecular orientation dependence of hole-injection barrier in pentacene thin film on the Au surface in organic thin film transistor
Authors: Ihm Kyuwook , Kim Bongsoo , Kang Tai-Hee , Kim Ki-Jeong , Joo Min Ho , Kim Tae Hyeong , Yoon Sang Soo , Chung Sukmin
Published: July 2006

We have investigated the effects of a buffer layer insertion on the performance of the pentacene based thin film transistor with a bottom contact structure. When the pentacene molecules have a standing up coordination on the Au surface that is modified by the benzenethiol or methanethiol, the transition region in the pentacene thin film is removed along the boundary between the Au and silicon oxide region, and the hole-injection barrier decreases by 0.4eV. Pentacene on various surfaces showed that the highly occupied molecular level is 0.2–0.4eV lower in the standing up coordination than in the lying down coordination.
Local discharge and distribution of wall charge in coplanar dielectric barrier discharge
Authors: Ouyang Jiting , He Feng , Feng Shuo , Yu Zhinong , Liang Zhihu , Wang Jianqi
Published: July 2006

The local discharge and wall charge distribution on dielectric surface in coplanar dielectric barrier discharge have been studied experimentally by employing a segment-electrode system. The results show that the local discharge currents on the segment electrodes are different when the segments act as cathode and/or anode, but the charge transfers during the current pulses are symmetric on the correlative parts of the electrodes. The wall charge distribution and the wall voltage during afterglow are uniform on the dielectric layer above the segments near the coplanar gap, while they decrease outwards in the outer side of the electrode if the voltage supply is not high enough. The segment-electrode configuration provides a possible way to investigate the local processes of the discharge in dielectric barrier discharge.
Selective generation of local ferromagnetism in austenitic stainless steel using nanoindentation
Authors: Sort J. , Concustell A. , Menéndez E. , Suriñach S. , Baró M. D. , Farran J. , Nogués J.
Published: July 2006

Periodic arrays of magnetic structures with micrometrer and submicrometer lateral sizes have been prepared at the surface of an austenitic stainless steel by means of local deformation using a nanoindenter. This method takes advantage of the phase transformation (from nonmagnetic fcc austenite to ferromagnetic bct martensite) which occurs in this material upon plastic deformation. The local character of the induced ferromagnetism is confirmed by magneto-optical Kerr effect measurements together with magnetic force microscopy imaging. The generated ferromagnetism can be subsequently erased by subjecting the deformed steel to annealing processes at temperatures above the reverse, martensite-to-austenite, phase transformation temperature.
Fluid dielectric loading on leaky Lamb wave of a piezoelectric plate
Authors: Lee Yung-Chun , Kuo Shi Hoa
Published: July 2006

This letter reports a high-precision wave measurement system for accurately determining the velocity of leaky Lamb wave. For an X-cut LiNbO3 plate, the change in leaky Lamb wave velocity induced by fluid’s dielectric loading effect has been measured. The measured correlation between fluid’s permittivity and induced wave velocity variation has been compared with theoretical results obtained form partial wave theory. Good agreements are observed. Potential applications of this wave measurement system are addressed.
Remotely coupled surface plasmons in a metal/insulator/Si structure perforated with periodic square hole arrays
Authors: Chuang Tzu-Hung , Tsai Ming-Wei , Chang Yi-Tsung , Lee Si-Chen
Published: July 2006

The zero-order transmission of radiation through a metal/dielectric structure perforated with square hole arrays is strongly enhanced when incident light resonates with surface plasmons (SPs). Surprisingly, when a metal/dielectric double layer, such as Ag∕SiO2, is fabricated on a silicon substrate, the Ag∕Si SP mode by coupling Ag and Si across the intermediate dielectric film has been found. It is named the remotely coupled surface plasmon. The transmission intensity is investigated as a function of the intermediate SiO2 thickness. The coupling lengths between Ag and Si in order to form the Ag∕Si SP mode are determined as well, and they turn out to be 500 and 130nm for couplings through air and a SiO2 layer, respectively.
Single-molecule detection of structural changes during Per-Arnt-Sim (PAS) domain activation
Authors: Zhao Jason Ming , Lee Haeshin , Nome Rene A. , Majid Sophia , Scherer Norbert F. , Hoff Wouter D.
Published: July 2006

The Per-Arnt-Sim (PAS) domain is a ubiquitous protein module with a common three-dimensional fold involved in a wide range of regulatory and sensory functions in all domains of life. The activation of these functions is thought to involve partial unfolding of N- or C-terminal helices attached to the PAS domain. Here we use atomic force microscopy to probe receptor activation in single molecules of photoactive yellow protein (PYP), a prototype of the PAS domain family. Mechanical unfolding of Cys-linked PYP multimers in the presence and absence of illumination reveals that, in contrast to previous studies, the PAS domain itself is extended by ≈3 nm (at the 10-pN detection limit of the measurement) and destabilized by ≈30% in the light-activated state of PYP. Comparative measurements and steered molecular dynamics simulations of two double-Cys PYP mutants that probe different regions of the PAS domain quantify the anisotropy in stability and changes in local structure, thereby demonstrating the partial unfolding of their PAS domain upon activation. These results establish a generally applicable single-molecule approach for mapping functional conformational changes to selected regions of a protein. In addition, the results have profound implications for the molecular mechanism of PAS domain activation and indicate that stimulus-induced partial protein unfolding can be used as a signaling mechanism.
Chemoresponsive monolayer transistors
Authors: Guo Xuefeng , Myers Matthew , Xiao Shengxiong , Lefenfeld Michael , Steiner Rachel , Tulevski George S. , Tang Jinyao , Baumert Julian , Leibfarth Frank , Yardley James T. , Steigerwald Michael L. , Kim Philip , Nuckolls Colin
Published: July 2006

This work details a method to make efficacious field-effect transistors from monolayers of polycyclic aromatic hydrocarbons that are able to sense and respond to their chemical environment. The molecules used in this study are functionalized so that they assemble laterally into columns and attach themselves to the silicon oxide surface of a silicon wafer. To measure the electrical properties of these monolayers, we use ultrasmall point contacts that are separated by only a few nanometers as the source and drain electrodes. These contacts are formed through an oxidative cutting of an individual metallic single-walled carbon nanotube that is held between macroscopic metal leads. The molecules assemble in the gap and form transistors with large current modulation and high gate efficiency. Because these devices are formed from an individual stack of molecules, their electrical properties change significantly when exposed to electron-deficient molecules such as tetracyanoquinodimethane (TCNQ), forming the basis for new types of environmental and molecular sensors.
TIP-1 Has PDZ Scaffold Antagonist Activity
Authors: Alewine Christine , Olsen Olav , Wade James B. , Welling Paul A.
Published: July 2006

PDZ proteins usually contain multiple protein–protein interaction domains and act as molecular scaffolds that are important for the generation and maintenance of cell polarity and cell signaling. Here, we identify and characterize TIP-1 as an atypical PDZ protein that is composed almost entirely of a single PDZ domain and functions as a negative regulator of PDZ-based scaffolding. We found that TIP-1 competes with the basolateral membrane mLin-7/CASK complex for interaction with the potassium channel Kir 2.3 in model renal epithelia. Consequently, polarized plasma membrane expression of Kir 2.3 is disrupted resulting in pronounced endosomal targeting of the channel, similar to the phenotype observed for mutant Kir 2.3 channels lacking the PDZ-binding motif. TIP-1 is ubiquitously expressed, raising the possibility that TIP-1 may play a similar role in regulating the expression of other membrane proteins containing a type I PDZ ligand.
QKI Binds MAP1B mRNA and Enhances MAP1B Expression during Oligodendrocyte Development
Authors: Zhao Lixia , Ku Li , Chen Yuntao , Xia Mingjing , LoPresti Patrizia , Feng Yue
Published: July 2006

Microtubule-associated protein 1B (MAP1B) is essential for neural development. Besides the abundant expression in neurons, MAP1B recently was found in myelinating oligodendroglia. Moreover, MAP1B deficiency causes delayed myelin development, suggesting the functional importance of MAP1B in oligodendroglia. However, molecular mechanisms that control MAP1B expression in oligodendroglia remain elusive. We report here that MAP1B mRNA is markedly up-regulated in the oligodendroglia cell line CG4 upon induced differentiation, leading to elevated MAP1B protein production. A coordinated regulation of homeoprotein transcription factors was observed during CG4 cell differentiation, which recapitulates the regulation in neurons that promotes MAP1B transcription. Hence, transcriptional regulation of MAP1B appears to be a common mechanism in both neurons and oligodendroglia. In addition, we found posttranscriptional regulation of MAP1B mRNA by the selective RNA-binding protein QKI in oligodendroglia. The 3′UTR of MAP1B mRNA interacts with QKI, and oligodendroglia-specific QKI-deficiency in the quakingviable mutant mice resulted in reduced MAP1B mRNA expression. Moreover, RNAi-mediated QKI-knockdown caused destabilization of the MAP1B mRNA in CG4 cells. Furthermore, forced expression of exogenous QKI was sufficient for promoting MAP1B expression. Because QKI is absent in neurons, QKI-dependent stabilization of MAP1B mRNA provides a novel mechanism for advancing MAP1B expression specifically in oligodendroglia during brain development.
Vitamin D supplementation increases the attractiveness of males' scent for female Iberian rock lizards
Authors: Martín José , López Pilar
Published: July 2006

Evolutionary theory proposes that signals used in sexual selection can only be stable if they are honest and condition dependent. However, despite the fact that chemical signals are used by many animals, empirical research has mainly focused on visual and acoustic signals. Vitamin D is an essential nutrient for lizards, but in some lizards its precursor (cholesta-5,7-dien-3-ol=provitamin D) is found in femoral gland secretions, which males use for scent marking and intraspecific communication. By allocating provitamin D to secretions, males might need to divert vitamin D from metabolism. This might be costly and condition dependent. We tested whether diet quality affected chemical signals of male Iberian rock lizards (
Lacerta monticola
) and its consequences for sexual selection. After experimental supplementation of dietary vitamin D, males increased the proportion of provitamin D in femoral secretions. Further experiments showed that females detected these changes in males' signals by chemosensory cues, and discriminated provitamin D, and changes in its concentration, from similar steroids (i.e. cholesterol) found in secretions. Moreover, females preferred areas scent marked by males with more provitamin D in their secretions. This mechanism would confer honesty to chemical signals of male lizards, and, thus, females may rely on it to select high-quality males. We suggest that the allocation of vitamins and other essential nutrients to either visual (e.g. carotenoids) or chemical ornaments might be the common basis of honest sexual displays in many animals.
Biotic homogenization and changes in species diversity across human-modified ecosystems
Authors: Smart Simon M , Thompson Ken , Marrs Robert H , Le Duc Mike G , Maskell Lindsay C , Firbank Leslie G
Published: July 2006

Changing land use and the spread of ‘winning’ native or exotic plants are expected to lead to biotic homogenization (BH), in which previously distinct plant communities become progressively more similar. In parallel, many ecosystems have recently seen increases in local species (α-) diversity, yet γ-diversity has continued to decline at larger scales. Using national ecological surveillance data for Great Britain, we quantify relationships between change in α-diversity and between-habitat homogenizations at two levels of organization: species composition and plant functional traits. Across Britain both increases and decreases in α-diversity were observed in small random sampling plots (10–200 m
2
) located within a national random sample of 1 km square regions. As α-diversity declined (spatially in 1978 or temporally between 1978 and 1998), plant communities became functionally more similar, but species-compositional similarity declined. Thus, different communities converged on a narrower range of winning trait syndromes, but species identities remained historically contingent, differentiating a mosaic of residual species-poor habitat patches within each 1 km square. The reverse trends in β-diversity occurred where α-diversity increased. When impacted by the same type and intensity of environmental change, directions of change in α-diversity are likely to depend upon differences in starting productivity and disturbance. This is one reason why local diversity change and BH across habitats are not likely to be consistently coupled.
ISODISPLACE: a web-based tool for exploring structural distortions
Authors: Campbell Branton J. , Stokes Harold T. , Tanner David E. , Hatch Dorian M.
Published: July 2006

ISODISPLACEis a new internet-server tool for exploring structural phase transitions. Given parent-phase structural information, it generates atomic displacement patterns induced by irreducible representations of the parent space-group symmetry and allows a user to visualize and manipulate the amplitude of each distortion mode interactively.ISODISPLACEis freely accessible at http://stokes.byu.edu/isodisplace.htmlviacommon internet browsers.
SITCOM: a program for comparing sites in macromolecular substructures
Authors: Dall'Antonia Fabio , Schneider Thomas R.
Published: July 2006

The programSITCOM, which can be used to facilitate the comparison of macromolecular substructures from different sources for validation purposes and to construct a consensus model containing sites from different substructures, is described.
A novel method for crystal control: synthesis and design of strontium carbonate with different morphologies by supported liquid membrane
Authors: Sun Dong-Mei , Wu Qing-Sheng , Ding Ya-Ping
Published: July 2006

A biomimetic supported liquid membrane (SLM) system was employed to control the morphology of strontium carbonate. Some interesting morphologies, including rods, shuttles and spheres, can be readily generated by using citric acid, nitrilotriacetic acid and ethylenediaminetetraacetic acid as cooperative modifiers in the mineralization process, under the conditions of pH 10, 0.01% of crystal modifier and ambient temperature. Seeking the cooperative balance of the SLM, the modifier agent and its concentration is the key factor in this system. In addition, this method was successfully applied to the morphology control of other alkaline earth metal carbonates, indicating its general applicability in materials preparation.
Polycrystal elastic constants for triclinic crystal and physical symmetry
Authors: Morris Peter R.
Published: July 2006

The problem of obtaining the Voigt average for the elastic stiffnesses with texture-describing weight functions has been solved for triclinic crystal and physical symmetries. The average is obtained by expanding theTijklmnpq, which relate the elastic stiffnesses in the rotated reference frame, c^{\,\prime}_{ijkl}, to those of the principal elastic stiffnesses,cmnpq, in generalized spherical harmonics, multiplying by the orientation distribution function and integrating over all orientations. The condition imposed to assure a unique expansion results in the absence of terms with oddL, so that the results are completely determinable from conventional X-ray pole figures. This is the most general case, from which all higher-symmetry solutions may be obtained by application of symmetry operations. The Reuss average for elastic compliances may be obtained in a similar fashion.
Analytical formulation of the variance method of line-broadening analysis for Voigtian X-ray diffraction peaks
Authors: Sánchez-Bajo Florentino , Ortiz Angel L. , Cumbrera Francisco L.
Published: July 2006

An alternative formulation of the variance method for the line-broadening analysis of polycrystalline materials is presented. It maintains the theoretical basis of the earlier formulations of the variance method, but differs in the manner of calculating the variance coefficients of the line profiles. In the proposed formulation, these are evaluated analytically in terms of the shape parameters of Voigt functions fitted to the X-ray diffraction data. Explicit expressions are thus derived for calculating the (surface-weighted) crystal sizes and (root-mean-square) lattice microstrains from the integral breadths of the Gauss and Lorentz components of the Voigt functions that model the experimental and instrumental line profiles.
Powder diffraction: the new automatic least-squares Fourier recycling procedure inEXPO2005
Authors: Altomare Angela , Cuocci Corrado , Giacovazzo Carmelo , Moliterni Anna Grazia Giuseppina , Rizzi Rosanna
Published: July 2006

The Rietveld method is the most widely used approach for refining crystal structures from powder diffraction patterns. It requires sufficiently accurate structure models and user skill. A method is described which is often able to complete and refine a structure model by using an automatic least-squares procedure applicable to reflection integrated intensities. A weighting scheme has been devised that is capable of taking into account the lower accuracy of the estimates of the overlapping reflections.
Anisotropic diffraction-line broadening due to microstrain distribution: parametrization opportunities
Authors: Leineweber Andreas
Published: July 2006

A correlated Gaussian lattice-parameter distribution of an ensemble of crystals, as leading to line broadening in the course of powder diffraction, can be associated with a correlated Gaussian microstrain distribution. The latter can be described in terms of a fourth-rank covariance tensor containing as its 81 componentsEijpq, the variances and the covariances of the nine components ∊ijof the symmetric second-rank strain tensor (formulated with respect to Cartesian coordinates),i.e.Eijpq= 〈∊ij∊pq〉. The restrictions for theEijpqtensor components resulting from assumed crystal class-symmetry invariance are the same as expected for certain fourth-rank property tensors, like compliancy. The parametrization of anisotropic microstrain broadening (e.g.in the course of Rietveld refinement) on the basis of the covariance tensor componentsEijpqhas, in comparison with earlier approaches, the advantage of straightforward recognizability of the case of isotropic microstrain broadening, independently of the actual crystallographic coordinate system.
Rapid, accurate phase quantification of multiphase calcium phosphate materials using Rietveld refinement
Authors: Reid Joel W. , Hendry Jason A.
Published: July 2006

Rietveld refinement has been employed to estimate the crystalline phase compositions of multiphase calcium phosphate mixtures containing calcium hydroxyapatite [Ca5(PO4)3OH], and alpha and beta tricalcium phosphate [Ca3(PO4)2]. Two methods were employed using fixed structural models for all three phases and refining the zero offset, scale factors, lattice parameters and one peak breadth parameter using either a constant background (method A) or a background with two refined parameters (method B). Analysis of a matrix of quantitative standards across a broad spectrum of phase compositions indicates that method A results in small systematic deviations of the Rietveld phase compositions (< 1 wt%) from the nominal values, but the systematic deviations are eliminated by refining the background (method B). The methods require approximately 10 min to complete, and are suitable for quality control of calcium phosphate production (and potentially other multiphase systems) when accuracy, precision and time are all significant considerations.
A simple and low-cost solution for the automation of X-ray powder diffractometers with chart recorder output
Authors: Jayaprakasan M. , Kannan V. , Ramasamy P.
Published: July 2006

X-ray powder diffraction is an established method for the qualitative identification of crystalline materials and their quantitative analysis. The new generation of X-ray diffraction systems are based on expensive digital/embedded control technology and computer interfaces. Yet many laboratories use conventional manual-controlled systems withXYstrip-chart recorders. Since the output spectrum is a strip chart (hard copy), raw data, essential for structural and qualitative analysis, are not readily available for further analysis. Upgrading to modern computerized diffractometers is very expensive. The proposed automation design described here is intended to enable the conventional diffractometer user to collect, store and analyze data quickly. The design also improves the resolution by five times compared with the conventional setup. For the automation, a PC add-on card has been designed to control and collect the timing and intensity counts from the conventional X-ray diffractometer, and suitable software has been developed to collect, process and present the X-ray diffraction data for both qualitative and quantitative analysis. Moreover, a major advantage of this design is that it does not warrant any physical modification of the hardware of the conventional setup; it is simply an extension to enhance the performance of collecting raw data with a higher resolution at desired intervals/timings.
Comparison of the anticoagulant effect of a direct thrombin inhibitor and a low molecular weight heparin in an acquired antithrombin deficiency in children with acute lymphoblastic leukaemia treated with l‐asparaginase: an in vitro study
Authors: Kuhle Stefan , Lau Alice , Bajzar Laszlo , Vegh Patsy , Halton Jacqueline , Cherrick Irene , Anderson Ron , Desai Sunil , McCusker Patricia , Wu John , Abshire Thomas , Mahoney Donald , Mitchell Lesley
Published: July 2006

Thrombosis occurs in 37% of children with acute lymphoblastic leukaemia (ALL) and is related to an l‐asparaginase‐induced acquired antithrombin (AT) deficiency. The incidence dictates the need for anticoagulant prophylaxis. Direct thrombin inhibitors (DTI) are independent of AT for effect and may thus have advantages in this population. The objective of this study was to determine the interaction of an AT deficiency with the anticoagulant effects of a DTI and a low molecular weight heparin (LMWH). Plasma samples from children with ALL were pooled (mean AT 0·53 U/ml). LMWH 0·3 and 0·7 U/ml or melagatran 0·3 and 0·5 μmol/l were added to the pools, then divided and AT was added back to one aliquot. In additional experiments, AT was added to AT immuno‐depleted plasma. Endogenous thrombin generation capacity (ETGC) was assessed by the continuous method. In plasma with LMWH, there was a 66–88% decrease in ETGC in AT‐normalised samples compared with neat. Conversely, no significant difference in ETGC with or without AT added for melagatran was seen. Experiments with AT‐depleted plasma showed no effect of AT level on anticoagulant activity of DTI, but a significant relationship for LMWH. By contrast to LMWH, DTI provides a consistent anticoagulant response independent of AT levels in children with AT deficiency.
Mediterranean hatchling lizards grow faster at higher altitude: a reciprocal transplant experiment
Authors: IRAETA P. , MONASTERIO C. , SALVADOR A. , DÍAZ J. A.
Published: July 2006

In reptiles, growth is subject to proximate environmental influences, such as food availability and temperature, that may be crucial during the early stages of postnatal development. Mediterranean regions, with their severe summer drought, offer an excellent opportunity to examine the effects of environmental variations in precipitation and productivity on the timing of reproduction and growth rates of lizards.

In this study, we compared the incubation time, size at hatching, growth rates and changes in juvenile body condition of two nearby populations of the lizard Psammodromus algirus separated by 600–700 m altitude in central Spain. We combined a reciprocal incubation experiment at 27 and 30 °C with a reciprocal transplant experiment to distinguish between environmental and population‐specific sources of geographical variation.

At both temperatures, eggs from the high‐elevation site hatched sooner. Several important phenotypic traits of juveniles were primarily determined by the growing environment: the high‐elevation site provided more food and allowed hatchlings to grow faster and reach larger size.

Environmental effects overrode familial ones, as shown by the larger growth rate of half‐sibs released at the high‐elevation site. However, both the size and the growth rate of juveniles were also influenced by their mother's site of origin, which means that population differences may reflect a genetic differentiation and/or different maternal effects.

Low precipitation and associated food scarcity were seemingly the main factors constraining the growth rates of juveniles at the lowland site.
Functional analysis of the sea urchin‐derived arylsulfatase (Ars)‐element in mammalian cells
Authors: Watanabe Satoshi , Watanabe Sachiko , Sakamoto Naoaki , Sato Masahiro , Akasaka Koji
Published: July 2006

An insulator is a DNA sequence that has both enhancer‐blocking activity, through its ability to modify the influence of neighboring cis‐acting elements, and a barrier function that protects a transgene from being silenced by surrounding chromatin. Previously, we isolated and characterized a 582‐bp‐long element from the sea urchin arylsulfatase gene (Ars). This Ars‐element was effective in sea urchin and Drosophila embryos and in plant cells. To investigate Ars‐element activity in mammalian cells, we placed the element between the cytomegalovirus enhancer and a luciferase (luc) expression cassette. In contrast to controls lacking the Ars‐element, NIH3T3 and 293T cells transfected with the element‐containing construct displayed reduced luciferase activities. The Ars‐element therefore acts as an enhancer‐blocking element in mammalian cells. We assessed the barrier activity of the Ars‐element using vectors in which a luc expression cassette was placed between two elements. Transfection experiments demonstrated that luc activity in these vectors was approximately ten‐fold higher than in vectors lacking elements. Luc activities were well maintained even after 12 weeks in culture. Our observations demonstrate that the Ars‐element has also a barrier activity. These results indicated that the Ars‐element act as an insulator in mammalian cells.