bluuebunny/crossref_metadata_2025 huggingface dataset:
Elongation and gene expression in bovine cloned embryos transferred to temporary recipients
Authors: Rodríguez-Alvarez Lleretny , Cox José , Navarrete Felipe , Valdés Cristián , Zamorano Teresa , Einspanier Ralf , Castro Fidel Ovidio
Published: June 2009

Elongated embryos provide a unique source of information about trophoblastic differentiation, gene expression and maternal-embryonic interactions; however they are difficult and costly to obtain, especially elongated cloned embryos. One alternative is their production in heterologous temporary recipients such as sheep and goats. We aimed to produce elongated bovine cloned embryos using heterologous transfer to temporary recipients. Day-7 cloned cattle blastocysts were transferred to the uteri of ewes and goats and recovered as elongated structures at day 17. We evaluated elongation, length, presence of embryonic disc and expression of several important genes for embryonic development. We also produced homologous (cloned cattle embryos transferred into cattle uteri). Cloned bovine blastocysts were able to proceed with preimplantation development through elongation with high efficiency despite the species to which they were transferred. In qualitative and quantitative RT-PCR experiments we found differences in the pattern of gene expression among embryos recovered from different species. Sox2, Nanog and FGF-4 were markedly deregulated. No previous reports about the expression pattern of the studied genes had been published for elongated bovine cloned embryos produced in intermediate recipients, furthermore, the pattern of expression of Nanog, Oct4, Eomes, Cdx2, IFN-tau, Dicer, FGF-4 and Sox2 shown here are novel for elongated cloned bovine embryos created by hand-made cloning. Our data confirmed that sheep and goats can be used as temporary recipients. This model could serve as a basis for further research on gene expression and cellular changes during bovine peri-implantation development.
Among the dissenters: reciprocal ethnography in nineteenth-century Inglistan
Authors: Green Nile
Published: June 2009

The emergence of ‘fieldwork’ as a technique for gathering knowledge was part of a reciprocal process of two-way observation between Europeans and Asians. The methods of language-learning, cultural immersion, and note-taking that were eventually canonized in the discipline of anthropology were no more unique to Europeans than the writing of the learned travelogues through which they first found expression. In the early nineteenth century, Asian travellers were observing and taking notes on the English at home as part of a reciprocal pattern of exchanges made possible by the new commercial and diplomatic contacts of the age. This thesis is demonstrated by using the Persian travel diary made by an Iranian ‘fieldworker’ to reconstruct in detail the methods and conditions of his ‘ethnographic’ tour of the English West Country in 1818. In the reversal of a familiar trope of European ethnography, the diary described meetings with the ‘sects’ and ‘mystics’ of the English provinces in the very same years that saw the first English accounts ofPersia religiosa.Using numerous contemporary English sources to build on the Persian field diary, the article reveals the multiple patterns of reciprocity by which knowledge was gained through a ‘scientific’ epistemology of observation and experience. From Unitarianism to Baha’ism, the collaborative knowledge so created led to changing intellectual attitudes among both European and Asian scholar-travellers.

The well informed of all denominations are the most liberal.

(W. J. Fox,A sermon on free inquiry in matters of religion, 1815)
Origin and dynamics of mesoscale eddies in the Catalan Sea (NW Mediterranean): Insight from a numerical model study
Authors: Rubio A. , Barnier B. , Jordà G. , Espino M. , Marsaleix P.
Published: June 2009

Past observations and satellite sea surface temperature imagery indicate the presence of mesoscale anticyclonic eddies drifting along the Catalan coast. In September 2001 one of these anticyclonic eddies was surveyed over the shelf break during an oceanographic cruise which permitted the 3‐D description of its structure. In this work we investigate the origin and dynamics of such “Catalan eddies” using a numerical circulation model of the northwest Mediterranean at 3 km resolution driven by high‐resolution atmospheric analyses and compare model eddies with the observations in the Catalan Sea. We identify two zones of eddy formation in the Gulf of Lions, in front of the city of Marseille and at the southeast of coast of Roussillon, from which anticyclonic eddies are observed to drift toward the Catalan Sea. The hydrology and dynamics of the structures observed in the simulations are characterized. Sensitivity experiments and energy analysis are performed which allow us to identify the mechanisms associated with their generation. Properties of the eddy observed during the 2001 cruise at the Catalan shelf break are found to compare well with model eddies generated at the southeast of the Roussillon coast. The model relates the origin of these eddies to the separation of the coastal current downstream from Creus Cape: flow separation is linked to intense downwelling taking place in front of the Roussillon coast when strong northwesterly winds events occur.
Reply to comment by Igor Esau on “Do stable atmospheric layers exist?”
Authors: Lovejoy S. , Tuck A. F. , Schertzer D. , Hovde S. J.
Published: June 2009

We would like to thank Esau (2009) for attempting to save the classical notion of stable layers; his argument is very close to one raised up by an anonymous reviewer of Lovejoy et al. (2008b). Since a similar argument is often invoked to justify atmospheric applications of linear gravity wave theories, it appears to be widespread in the community. We therefore hope this debate will clarify the issue.
Kilauea slow slip events: Identification, source inversions, and relation to seismicity
Authors: Montgomery‐Brown E. K. , Segall P. , Miklius A.
Published: June 2009

Several slow slip events beneath the south flank of Kilauea Volcano, Hawaii, have been inferred from transient displacements in daily GPS positions. To search for smaller events that may be close to the noise level in the GPS time series, we compare displacement fields on Kilauea's south flank with displacement patterns in previously identified slow slip events. Matching displacement patterns are found for several new candidate events, although displacements are much smaller than previously identified events. One of the candidates, 29 May 2000, is coincident with a microearthquake swarm, as are all of the previously identified slow slip events. The microearthquakes follow the onset of slow slip, implying that they are triggered by stress changes during slip. The new slow slip event brings the total number of events on Kilauea, between 1997 and 2007, to eight, the smallest having MW = 5.3, and the largest having MW = 6.0. While the recurrence time between the four largest events is 2.11 ± 0.01 years, the repeat time for all eight events is 0.9 ± 0.6 years. We invert for the fault geometry and distribution of slip during the slow slip events. The optimal source depths of 5 km, assuming uniform slip dislocations in an elastic half‐space, are considerably shallower than the accompanying swarm earthquakes (6.5–8.5 km), which would place the earthquakes in a zone of decreased Coulomb stress. Inversions including the effects of topography and layered elastic structure in the forward models favor depths comparable to microearthquake depths, such that the earthquakes are located in a region of increased Coulomb stress. We also invert for time‐dependent fault slip directly from the 30 s GPS phase observations, constraining the source to the optimal uniform slip geometry. On the basis of these inversions, the larger events last between 1.5–2.2 days. The data are unable to resolve migration of slip along the fault. The temporal pattern of accompanying microearthquakes is consistent with the fault slip history assuming a seismicity rate theory based on rate and state‐friction, making the swarm earthquakes coshocks and aftershocks of the slow slip events.
Photochemical histories of nonmethane hydrocarbons inferred from their stable carbon isotope ratio measurements over east Asia
Authors: Saito Takuya , Kawamura Kimitaka , Tsunogai Urumu , Chen Tai‐Yih , Matsueda Hidekazu , Nakatsuka Takeshi , Gamo Toshitaka , Uematsu Mitsuo , Huebert Barry J.
Published: June 2009

The first airborne measurements of stable carbon isotope ratios (δ13C) of nonmethane hydrocarbons (NMHCs) were made over east Asia and its downwind regions as part of the Asian Pacific Regional Aerosol Characterization Experiment (ACE‐Asia). The measured δ13C values for ethane, n‐butane, and n‐pentane varied from approximately −30‰ to −20‰. In contrast, acetylene showed much higher δ13C with a wide variation (−10‰ to +20‰). These are consistent with the high δ13C values of combustion‐derived acetylene and a significant isotopic fractionation due to photochemical removal process. Vertical profiles of δ13C‐derived photochemical ages of NMHCs differed from one NMHC to another: less reactive ethane and acetylene showed linear increases in age with altitude (∼8 days below 1 km to ∼20 days at about 6 km altitude), whereas more reactive n‐butane and n‐pentane (∼4 days) had no age gradient. This suggests that less reactive NMHCs in high‐altitude air are transported from upwind source regions and mixed with fresh emissions from east Asia, while reactive NMHCs, even in the free troposphere, have recently been emitted. Thus vertical profiles are caused by the mixing of fresh emissions with aged air masses containing reactivity‐determined amounts of photochemically aged NMHCs. This mixing causes the difference in the photochemical ages calculated by two methods (the “hydrocarbon clock” method using n‐butane/ethane ratios and the “isotopic hydrocarbon clock” method using δ13C values of ethane).
Mesoproterozoic plume‐modified orogenesis in eastern Precambrian Australia
Authors: Betts Peter G. , Giles David , Foden John , Schaefer Bruce F. , Mark Geordie , Pankhurst Matthew J. , Forbes Caroline J. , Williams Helen A. , Chalmers Neil C. , Hills Quinton
Published: June 2009

Tectonic models for the latest Paleoproterozoic to earliest Mesoproterozoic evolution of eastern Australia (circa 1620–1500 Ma) are diverse and either emphasize plume or plate margin activity, neither of which satisfactorily explains all geological observations. The dichotomy is largely attributed to geochemical, spatial and temporal data that suggest voluminous A‐type felsic magmas are plume related, whereas distribution of arc‐related magmas and intense orogenic overprint suggest plate margin activity. The salient geological events include arc‐related magmatism at circa 1620–1610 Ma followed by a magmatic hiatus coincident with north‐south crustal shortening (1610–1590 Ma) and a magmatic flare‐up of A‐type felsic magmas throughout the Gawler Craton (circa 1595–1575 Ma). These magmas form the oldest component of a northward younging hot spot track that extends to the Mount Isa Inlier. At circa 1590–1550 Ma, arc magmatism resumed along the northern margin of the Gawler Craton and the rest of eastern Australia records a 90° shift in the regional shortening direction related to activity along the eastern margin of the Australian continent. A plume‐modified orogenic setting satisfies all of the spatial and temporal relationships between magma generation and orogenic activity. In this model, the Gawler Craton and the adjacent subduction zone migrated over a mantle plume (circa 1620–1610 Ma). Resultant flat subduction caused transient orogenesis (1610–1595 Ma) in the overriding plate. Slab delamination and thermal assimilation of the plume and the subducting slab caused a switch to crustal extension in the overriding plate, resulting in extensive mantle‐derived and crustal melting in the Gawler Craton (1595–1575 Ma).
Retrieval of upper tropospheric relative humidity profiles over low clouds from the Atmospheric Infrared Sounder
Authors: Ishimoto Hiroshi
Published: June 2009

In this paper we discuss a method to retrieve humidity profiles in the upper troposphere using cloud‐affected radiances measured by the Atmospheric Infrared Sounder (AIRS). The magnitude of retrieval error for temperature and water vapor profiles caused by ignoring cloud presence depends strongly on the height of clouds as well as on the cloud fraction in the sensor's field of view. Error analysis based on radiative transfer calculations performed for 155 channels using a set of diverse atmospheric profiles shows that the relative humidity in the upper troposphere at pressure levels between 200 and 400 hPa could be estimated if the cloud height was lower than the height of the 800 hPa pressure level. Applying the channel ranking technique to evaluate the cloud influence in the observed spectra, we examined a high‐resolution humidity map of the upper troposphere over land and sea.
Size‐fractionated iron distribution on the northern Gulf of Alaska
Authors: Wu Jingfeng , Aguilar‐Islas Ana , Rember Robert , Weingartner Tom , Danielson Seth , Whitledge Terry
Published: June 2009

Concentrations of soluble (<0.025 μm), dissolved (<0.4 μm) and total (unfiltered) iron (Fe) were measured over the continental shelf and slope of the northern Gulf of Alaska (GoA) during spring‐summer. Large cross‐shelf gradients of surface water Fe concentrations were observed in these productive shelf waters during both seasons. Most of the particulate (>0.4 μm) and colloidal (0.025–0.4 μm) Fe size fractions were removed from surface waters within the inner and mid shelf. As a result the contribution of soluble Fe to the total Fe concentration increased from the inner shelf to the shelf break/slope waters. Surface water dissolved Fe concentrations on the northern GoA continental slope were higher than those previously observed in the central GoA gyre. Variations in surface water Fe concentrations from spring through summer appear to result from the changes in freshwater discharge and physical processes on the shelf.
Improved nearside gravity field of the Moon by localizing the power law constraint
Authors: Han Shin‐Chan , Mazarico Erwan , Lemoine Frank G.
Published: June 2009

The problem associated with the large data gap on the farside of the Moon is addressed for constructing a high‐resolution global gravity model. By localizing the power law constraint and making it effective only within the farside and limb regions, we mitigate the undesired power‐limiting effect on the nearside. Compared to the solution estimated from Lunar Prospector and other satellite tracking data with the globally‐applied power law, the locally‐constrained solution shows significant improvement of the nearside gravity estimates. Around the areas dominated by craters in the southern hemisphere of the nearside, the correlation with topography approaches nearly 0.95 and the admittance converges to 100–110 mGal/km up to spherical harmonic degree 130, while the globally‐constrained solutions distort starting at degree 90. The proposed analysis can benefit the science and operation of other existing and future planetary missions and enhance the geophysical interpretation of the gravity field.
Functional analysis of βC1 protein encoded by Tomato leaf curl Java virus, a monopartite begomovirus
Authors: Sharma Pradeep , Kon Tatsuya , Ikegami Masato
Published: June 2009

Tomato leaf curl disease is among the most important limiting factors that affect tomato production in world wide including south East Asia. Recently, we have isolated tomato leaf curl Java virus, a whitefly-transmitted monopartite begomovirus, which belongs to the family Geminiviridae. ToLCJAV have been shown to be associated with a novel signal stranded DNA satellite, known as [beta]DNA. Post transcriptional gene silencing (PTGS) in plants is a natural defense response against virus infections, and as a counter defense strategy, viruses have evolved to encode silencing suppressor proteins. The present work we have identified the suppressor activities encoded by [beta]C1 protein encoded by ToLCJAV DNA[beta] satellite, which poses a serious threat to Indonesia.
How do we quantify biodiversity? All the evidence in one place.
Authors: Lyashevska Olga
Published: June 2009

Biodiversity is a multi-dimensional concept that is represented by a large variety of measures. This complexity and lack of consistency limits the development of a coherent scientific understanding of biodiversity and how properties, such as ecosystem services, may depend on it. Here, I demonstrate that the formal discipline of creating a relational database (RDB) for information about biodiversity and its measures, is a useful tool in organising such knowledge into coherent sense. Following steps of the logical database design and data normalization to build a RDB, results in a formal definition of biodiversity within a well defined concept structure; mapping rules between the concepts of biodiversity and entities of RDB and a consistent information structure - all in one place. I show how this is then used to support evidence-based objective statements about biodiversity.
On the chain length dependence of local correlations in polymer melts and a perturbation theory of symmetric polymer blends
Authors: Morse David C. , Chung Jun Kyung
Published: June 2009

The self-consistent field (SCF) approach to the thermodynamics of dense polymer liquids is based on the idea that short-range correlations in a polymer liquid are almost independent of how monomers are connected into polymers over larger scales. Some limits of this idea are explored in the context of a perturbation theory for symmetric polymer blends. We consider mixtures of two structurally identical polymers, A and B, in which the AB monomer pair interaction differs slightly from the AA and BB interactions by an amount proportional to a parameter α. An expansion of the free energy to first order in α yields an excess free energy of mixing per monomer of the form αz(N)ϕAϕB in both lattice and continuum models, where z(N) is a measure of the number of intermolecular near neighbors per monomer in a one-component (α=0) reference liquid with chains of length N. The quantity z(N) decreases slightly with increasing N because the concentration of intramolecular near neighbors is slightly higher for longer chains, creating a slightly deeper intermolecular correlation hole. We predict that z(N)=z(∞)[1+βN¯−1/2], where N¯ is an invariant degree of polymerization and β=(6/π)3/2 is a universal coefficient. This and related predictions about the slight N dependence of local correlations are confirmed by comparison to simulations of a continuum bead-spring model and to published lattice Monte Carlo simulations. We show that a renormalized one-loop theory for blends correctly describes this N dependence of local liquid structure. We also propose a way to estimate the effective interaction parameter appropriate for comparisons of simulation data to SCF theory and to coarse-grained theories of corrections to SCF theory, which is based on an extrapolation of perturbation theory to the limit N→∞.
A comparison of diamond growth rate using in-liquid and conventional plasma chemical vapor deposition methods
Authors: Takahashi Yoshiyuki , Toyota Hiromichi , Nomura Shinfuku , Mukasa Shinobu , Inoue Toru
Published: June 2009

In order to make high-speed deposition of diamond effective, diamond growth rates for gas-phase microwave plasma chemical vapor deposition and in-liquid microwave plasma chemical vapor deposition are compared. A mixed gas of methane and hydrogen is used as the source gas for the gas-phase deposition, and a methanol solution of ethanol is used as the source liquid for the in-liquid deposition. The experimental system pressure is in the range of 60–150 kPa. While the growth rate of diamond increases as the pressure increases, the amount of input microwave energy per unit volume of diamond is 1 kW h/mm3 regardless of the method used. Since the in-liquid deposition method provides a superior cooling effect through the evaporation of the liquid itself, a higher electric input power can be applied to the electrodes under higher pressure environments. The growth rate of in-liquid microwave plasma chemical vapor deposition process is found to be greater than conventional gas-phase microwave plasma chemical vapor deposition process under the same pressure conditions.
Renormalized one-loop theory of correlations in polymer blends
Authors: Qin Jian , Morse David C.
Published: June 2009

The renormalized one-loop theory is a coarse-grained theory of corrections to the random phase approximation (RPA) theory of composition fluctuations. We present predictions of corrections to the RPA for the structure function S(k) and to the random walk model of single-chain statics in binary homopolymer blends. We consider an apparent interaction parameter χa that is defined by applying the RPA to the small k limit of S(k). The predicted deviation of χa from its long chain limit is proportional to N−1/2, where N is the chain length. This deviation is positive (i.e., destabilizing) for weakly nonideal mixtures, with χaN≲1, but negative (stabilizing) near the critical point. The positive correction to χa for low values of χaN is a result of the fact that monomers in mixtures of shorter chains are slightly less strongly shielded from intermolecular contacts. The predicted depression in χa near the critical point is a result of long-wavelength composition fluctuations. The one-loop theory predicts a shift in the critical temperature of O(N−1/2), which is much greater than the predicted O(N−1) width of the Ginzburg region. Chain dimensions are found to deviate slightly from those of a random walk even in a one-component melt and contract slightly as thermodynamic repulsion is increased. Predictions for S(k) and single-chain properties are compared to published lattice Monte Carlo simulations.
Evidence of transient species occurring in the reduction process of trivalent lanthanides under 2.5 MeV electron irradiation by in situ cathodoluminescence and time-resolved photoluminescence
Authors: Ollier N. , Boizot B. , L’henoret P. , Guillous S. , Petite G.
Published: June 2009

In situ cathodoluminescence and time-resolved photoluminescence measurements were carried out on Sm-doped glasses during a 2.5 MeV electron irradiation. These experiments allow characterizing more precisely the mechanisms operating under irradiation and more specifically the reduction processes of Sm3+ to Sm2+ ions. Sm2+ emission lines appear in the first steps of the irradiation, however, the D50→F70–2 emission lines of Sm2+ were not observed on the cathodoluminescence spectrum. Moreover, two sites of Sm2+ have been evidenced in the glasses; the formation of each species is clearly different. Relaxation processes of Sm3+ and Sm2+ leads to consider the existence of different transient states of Sm3+ and Sm2+ species which are annealed after irradiation. We propose some synthetic schemes of the reduction mechanisms produced during the irradiation.
A compact electron beam ion source with integrated Wien filter providing mass and charge state separated beams of highly charged ions
Authors: Schmidt M. , Peng H. , Zschornack G. , Sykora S.
Published: June 2009

A Wien filter was designed for and tested with a room temperature electron beam ion source (EBIS). Xenon charge state spectra up to the charge state Xe46+ were resolved as well as the isotopes of krypton using apertures of different sizes. The complete setup consisting of an EBIS and a Wien filter has a length of less than 1 m substituting a complete classical beamline setup. The Wien filter is equipped with removable permanent magnets. Hence total beam current measurements are possible via simple removal of the permanent magnets. In dependence on the needs of resolution a weak (0.2 T) or a strong (0.5 T) magnets setup can be used. In this paper the principle of operation and the design of the Wien filter meeting the requirements of an EBIS are briefly discussed. The first ion beam extraction and separation experiments with a Dresden EBIS are presented.
Multidimensional generalized-ensemble algorithms for complex systems
Authors: Mitsutake Ayori , Okamoto Yuko
Published: June 2009

We give general formulations of the multidimensional multicanonical algorithm, simulated tempering, and replica-exchange method. We generalize the original potential energy function E0 by adding any physical quantity V of interest as a new energy term. These multidimensional generalized-ensemble algorithms then perform a random walk not only in E0 space but also in V space. Among the three algorithms, the replica-exchange method is the easiest to perform because the weight factor is just a product of regular Boltzmann-like factors, while the weight factors for the multicanonical algorithm and simulated tempering are not a priori known. We give a simple procedure for obtaining the weight factors for these two latter algorithms, which uses a short replica-exchange simulation and the multiple-histogram reweighting techniques. As an example of applications of these algorithms, we have performed a two-dimensional replica-exchange simulation and a two-dimensional simulated-tempering simulation using an α-helical peptide system. From these simulations, we study the helix-coil transitions of the peptide in gas phase and in aqueous solution.
A set of sums for continuous dual q−2-Hahn polynomials
Authors: Gade R. M.
Published: June 2009

An infinite set {τ(l)(y;r,z)}r,l∊N0 of linear sums of continuous dual q−2-Hahn polynomials with prefactors depending on a complex parameter z is studied. The sums τ(l)(y;r,z) have an interpretation in context with tensor product representations of the quantum affine algebra Uq′(sl̂(2)) involving both a positive and a negative discrete series representation. For each l>0, the sum τ(l)(y;r,z) can be expressed in terms of the sum τ(0)(y;r,z), continuous dual q2-Hahn polynomials, and their associated polynomials. The sum τ(0)(y;r,z) is obtained as a combination of eight basic hypergeometric series. Moreover, an integral representation is provided for the sums τ(l)(y;r,z) with the complex parameter restricted by |zq|<1. This gives rise to a bilinear summation formula for the continuous dual q−2-Hahn polynomials.
Analysis of radio-frequency absorption and electric and magnetic field enhancements due to surface roughness
Authors: Zhang Peng , Lau Y. Y. , Gilgenbach R. M.
Published: June 2009

The radio-frequency (rf) power absorption due to a small hemispherical protrusion on a resonant cavity’s surface is computed analytically. This protrusion may assume arbitrary values of permittivity, permeability, and conductivity so that it may represent a foreign object. Under the assumption that the protrusion radius, a, is small compared with the rf wavelength, the power dissipated in the protrusion by the rf electric field and by the rf magnetic field are calculated explicitly. It is found that, in general, the heating by the rf magnetic field is dominant when δ/a<1, even for nonmagnetic materials, where δ is the skin depth associated with the protrusion material. The field enhancement factors for both the rf electric field and the rf magnetic field on the protrusion are also calculated analytically. They are found to decrease as δ/a increases. They are spot checked against the MAXWELL 3D code. These field enhancement factors are also consistent with the published results in the δ=0 limit, in which case the protrusion may represent a small local bump on the surface of a superconducting cavity.
Supramolecular structure of columnar liquid crystalline π-conjugated oligothiophenes with highly polarized photoluminescence properties
Authors: Minoura Kiyoshi , Akama Yusuke , Morita Jun , Yasuda Takuma , Kato Takashi , Shimomura Takeshi
Published: June 2009

It is possible to control the alignment of columnar liquid crystalline π-conjugated systems by controlling photoluminescence (PL) properties to yield a polarized PL effect by shear stress. A polarization ratio of 11.2 at the fluorescence peak was obtained using columnar liquid crystalline π-conjugated oligothiophenes [T. Yasuda et al., Adv. Funct. Mater. 19, 411 (2009)]. We have therefore revealed the directional distribution of oligothiophene molecules inside the columns, which is the origin of a highly polarized PL emission, through detailed analysis of the dependence of PL polarization ratio on the detection polar angle, assuming that such PL emission is due to the summation of all dipole radiations from oligothiophene molecules in the measured area of the sample.
Shadowgraphic studies of triazene assisted laser-induced forward transfer of ceramic thin films
Authors: Kaur K. S. , Fardel R. , May-Smith T. C. , Nagel M. , Banks D. P. , Grivas C. , Lippert T. , Eason R. W.
Published: June 2009

The laser-induced forward transfer process of solid ceramic donor materials (gadolinium gallium oxide and ytterbium doped yttrium aluminium oxide) was studied using triazene polymer as a sacrificial layer by means of a time-resolved nanosecond-shadowgraphy technique. The dependence of the ablation dynamics and quality of the ejected donor material on the laser fluence and thickness of the sacrificial and donor layers were investigated and discussed.
Thermally induced structural characteristics of pentacene thin films
Authors: Guo Dong , Ikeda Susumu , Saiki Koichiro
Published: June 2009

The influence of postdeposition thermal treatment on the structural characteristics of vacuum deposited pentacene thin films was systematically investigated. With increasing annealing temperature, the film crystallinity decreased regularly and significantly, while structural analysis by using the paracrystal theory revealed an increased vertical coherent diffraction domain size. Influence of the structural evolution on the thin film transistor performance was demonstrated by a variable temperature structural and electrical characterization. The results indicate that a thermally induced structural evolution should be generally taken into account for understanding the charge transport nature of the materials.
Spatially and tensor-resolved Raman analysis for the determination of phonon deformation potentials on the microscopic scale in Si single-crystal
Authors: Miyatake Takahiro , Porporati Alessandro Alan , Pezzotti Giuseppe
Published: June 2009

A spatial and tensor deconvolution procedure is proposed for the analysis of cumulative Raman frequency shifts recorded in silicon surface zones containing a Blister-type contact stress field. The procedure is further applied to the quantitative determination of the three independent values of phonon deformation potentials for the Si lattice. Phonon potentials are experimentally obtained for an (110) oriented Si single-crystal containing a pyramidal (Vickers) indentation print. A cross-polarized laser microprobe operating at a visible wavelength enabled us to precisely retrieve the three independent phonon potentials for Si. The presented method requires a minimum amount of material and can be applied with a single measurement set, while previously published characterizations required the availability of relatively large and differently oriented samples. The proposed experimental method is particularly suitable for in situ assessments of phonon deformation potentials in thin/opaque samples with high refractive index.
Surface and physical characteristics of ZnO:Al nanostructured films
Authors: Fang Te-Hua , Kang Shao-Hui
Published: June 2009

Structural and surface characterizations of the ZnO:Al nanostructured films were achieved by means of x-ray diffraction, scanning electron microscope, atomic force microscope, and nanoindentation measurements. The films exhibited hydrophobic behavior with contact angles of about 133.2°–142.7°, and a decrease in the hardness and Young’s modulus with decreasing indentation depths. Buckling behavior took place during the indentation process, and the fracture strength of the films was also investigated. The results show that the phase transformation from zinc blende to wurtzite structure. Also, it should be correlated with belongs to chairtype Peierls distortion with up to 38° tilting (001) rock-salt structure along the (1¯21¯0) plane and followed tilting along the (101¯0) plane by about 32° for a fair match with (101¯0) Zn. A nanogenerator with ZnO nanorods was then fabricated to define its piezoelectric characteristics. The power density per unit substrate area is about 18.3 μW/mm2.
Study of matching characteristics for Ni0.97−xZnxCo0.03Fe2O4 spinel ferrites
Authors: Li Z. W. , Kong L. B. , Yang Z. H.
Published: June 2009

A perfect matching chart is designed to obtain the matching frequency fm and the matching thickness tm of electromagnetic (EM) attenuation material. Based on the chart, the relationship between matching parameters (fm and tm) and high-frequency dynamic parameters [μ′(f), μ″(f), and ϵ′(f)] are studied for Ni0.97−xZnxCo0.03Fe2O4 (NiZnCo) spinel ferrites with x=0.5 and 0.65. At tm, the spinel ferrites exhibit excellent EM attenuation characteristics with low reflectivity and broad bandwidth at very high frequency and ultrahigh frequency bands.
Changing the three-dimensional magnetization exchange coupling of mixed Fe and V nanoclusters with hydrogen
Authors: Valev V. K. , Di Vece M. , Van Bael M. J. , Grandjean D. , Decoster S. , Vantomme A. , Verbiest T. , Lievens P.
Published: June 2009

The magneto-optical Kerr effect of an iron-vanadium nanocluster-assembled thin film was measured as a function of hydrogen content. Hydrogen has a clear effect on the magnetization of this three-dimensional exchange coupled system for both increasing and decreasing hydrogen pressures. This effect is attributed to the modification of the electronic properties of the nonmagnetic vanadium nanoclusters by hydrogen. Since vanadium mediates the exchange coupling between aggregated iron nanoclusters, the changes in magnetic properties are directly related to hydrogen absorption.
Phenomenological simulation of self-organization of microtubule driven by dynein c
Authors: Chen Q. , Li D. Y. , Oiwa K.
Published: June 2009

It was recently noticed that in vitro motility assays, driven by random distributed dynein c, microtubules could form self-organized circular patterns, which could be of importance to the design of nanobiomechanical machines. In order to determine key parameters that control the self-organized movement of microtubules, a phenomenological modeling study taking account of the microtubule joining probability distribution and microtubule bias was conducted to investigate the self-organization of microtubules driven by dynein motors.
Low temperature charge carrier hopping transport mechanism in vanadium oxide thin films grown using pulsed dc sputtering
Authors: Bharadwaja S. S. N. , Venkatasubramanian C. , Fieldhouse N. , Ashok S. , Horn M. W. , Jackson T. N.
Published: June 2009

Low temperature charge transport in vanadium oxide (VOx) thin films processed using pulsed dc sputtering is investigated to understand the correlation between the processing conditions and electrical properties. It is identified that the temperature dependent resistivity ρ(T) of the VOx thin films is dominated by a Efros–Shklovskii variable range hopping mechanism [Efros and Shklovskii, J. Phys. C 8, L49 (1975)]. A detailed analysis in terms of charge hopping parameters in the low temperature regime is used to correlate film properties with the pulsed dc sputtering conditions.
Interaction of acetonitrile with thin films of solid water
Authors: Bahr S. , Kempter V.
Published: June 2009

Thin films of water were prepared on Ag at 124 K. Their properties were studied with metastable impact electron spectroscopy, reflection absorption infrared spectroscopy, and temperature programmed desorption. The interaction of acetonitrile (ACN) with these films was studied with the abovementioned techniques. From the absence of any infrared activity in the initial adsorption stage, it is concluded that ACN adsorbs linearly and that the C≡N axis is aligned parallel to the water surface (as also found on neat Ag). Initially, the interaction with water surface species involves their dangling OD groups. During the completion of the first adlayer the ACN-ACN lateral interaction becomes of importance as well, and the ACN molecules become tilted with respect to the water surface. ACN shows propensity to stay at the surface after surface adsorption even during annealing up to the onset of desorption. The present results for the ACN-water interaction are compared with available classical molecular dynamics calculations providing the orientation profile for ACN on water as well as the ACN bonding properties.
Computing vibrational energy levels by using mappings to fully exploit the structure of a pruned product basis
Authors: Cooper Jason , Carrington Tucker
Published: June 2009

For the purpose of calculating (ro-)vibrational spectra, rate constants, scattering cross sections, etc. product basis sets are very popular. They, however, have the important disadvantage that they are unusably large for systems with more than four atoms. In this paper we demonstrate that it is possible to efficiently use a basis set obtained by removing, from a product basis set, functions associated with the largest diagonal Hamiltonian matrix elements. This is done by exploiting the fact that for every factor of every term in the Hamiltonian, there is a basis-set order in which the matrix representation of the factor is block diagonal. Due to this block diagonality the Lanczos algorithm can be implemented efficiently. Tests with model Hamiltonians with as many as 32 coordinates illustrate the merit of the ideas.
Magnetic order in amorphous (Fe0.25Nd0.75)0.6B0.4 nanoparticles
Authors: Tortarolo M. , Zysler R. D. , Romero H.
Published: June 2009

We have synthesized and study the magnetic properties of (Fe0.25Nd0.75)0.6B0.4 amorphous nanoparticles. These particles were prepared in dispersed (polymeric matrix) and powder systems in order to investigate both the internal magnetic order of the particles and the effects arising from the interactions among them. The results obtained for the dispersed particles evidence the presence of an internal magnetic structure of the particles with a magnetically ordered core plus a paramagnetic shell. At low temperature, the core magnetic moment interacts with the shell (intraparticle interaction) inducing an enhancement in the effective magnetic anisotropy of the particles, which is related to the sharp increase in the coercive field at low temperatures. The interparticle interactions affect mainly the surface spins and induce a decrease in the total magnetization of the particle.
Near-IR absorption saturation and mechanism of picosecond recovery dynamics of copper selenide nanostructured via alumina
Authors: Statkutė G. , Mikulskas I. , Tomašiūnas R. , Jagminas A.
Published: June 2009

Absorption saturation at 1.064 μm wavelength in Cu2−xSe material nanostructured by means of an original method—formation and hosting in an array of electrochemically grown alumina voids—was investigated. Columnlike channels provide growth of copper selenide in a shape of nanowire with a fixed diameter. Experimental results obtained from measuring nanowires of various diameters (∅10, 15, 20, and 70 nm) revealed that the ∅20 nm case is most efficient for absorption saturation, manifesting highest optical modulation depth and lowest interlevel transition rate evaluated. A model to analyze the conditions for absorption saturation and absorption recovery dynamics was developed. Depending on pump intensity the nonmonotonous increase in recovery time for the highest applied values was interpreted as filling up of states at an intermediate energy level. From modeling, important material science parameters, such as concentration of resonant and trapping/recombination states, interlevel transition rate, capture time, characteristic for copper selenide, have been evaluated and compared for different samples. Finally, the consequence of the model to a working copper selenide energy level scheme was considered.
A study of background signals in terahertz apertureless near-field microscopy and their use for scattering-probe imaging
Authors: Astley Victoria , Zhan Hui , Mendis Rajind , Mittleman Daniel M.
Published: June 2009

Apertureless near-field microscopy is an imaging technique in which a small metal tip is held close to a surface, converting evanescent waves to propagating waves and permitting extreme subwavelength spatial resolution. This technique has recently been adapted for use in the terahertz region of the spectrum. Here, the interpretation of the measured signals and the suppression of background scattering can be complicated by the extremely broad bandwidth of the terahertz source and by the coherent (i.e., phase-sensitive) detection of the scattered radiation. We have analyzed the use of tip-sample distance modulation for the removal of background signals. We find that significant background signals, originating from scattering off the probe tip, can be observed even after modulation. These background signals result from path-length difference modulation, and thus are relevant when phase-sensitive detection is used. We use a dipole antenna model to explain the spatial variation in the scattered signal. Since this signal originates from the tip only, it can be used to characterize free-space terahertz wave fronts with subwavelength resolution.
Dielectric and transport properties of carbon nanotube-CdS nanostructures embedded in polyvinyl alcohol matrix
Authors: Mondal S. P. , Aluguri R. , Ray S. K.
Published: June 2009

Multiwalled carbon nanotube-CdS/polyvinyl alcohol (MWCNT-CdS/PVA) composites have been grown by a simple chemical process on one-dimensional templates. The plane-view transmission electron micrographs clearly indicate the formation of nanocrystalline CdS on the nanotube surfaces. The superior dielectric behavior of the MWCNT-CdS nanostructures over MWCNT and PVA host matrices has been demonstrated. The dc and ac transport properties of CdS carbon nanotube-insulating polymer nanocomposites have been studied using impedance spectroscopy. An enhancement in optical band gap of nanocomposites over the bulk CdS has been observed due to the quantum confinement effect in CdS nanocrystals.
Study of geometrical effects on the characteristics of metallic double-walled carbon nanotube waveguides through quantum hydrodynamics
Authors: Ahmadizadeh Y. , Javaherian C. , Shokri B.
Published: June 2009

By assuming the metallic double-walled carbon nanotubes as two coaxial free electron gas layers with linearized hydrodynamic model, it is shown that surface plasmons coupled with electromagnetic fields can be excited on a metallic double-walled carbon nanotube and propagate along its axis. Dispersion relations of surface plasmons for E-type and B-type waves in various inner-outer radii and various interlayer distances for long metallic double-walled carbon nanotubes are obtained.
Whistler wave radiation from a loop antenna located in a cylindrical density depletion
Authors: Kudrin Alexander V. , Bakharev Pavel V. , Krafft Catherine , Zaboronkova Tatyana M.
Published: June 2009

Electromagnetic radiation from sources in a magnetoplasma containing a radially nonuniform cylindrical density depletion is considered. Using a rigorous solution for the total field comprising both the discrete and continuous parts of the spatial spectrum of excited waves, the radiation resistance of a loop antenna and the efficiency of excitation of different modes by such a source are determined in the whistler range. Based on the numerical results, conditions are revealed under which the power radiated from a loop antenna located in a density depletion is dominated by the contribution of either discrete- or continuous-spectrum modes. It is found that the radiation resistance of the loop antenna in a weakly nonuniform density depletion can be notably greater than that in a homogeneous magnetoplasma whose parameters coincide with those near the depletion axis. The results are relevant to the basic properties of whistler wave excitation in the presence of field-aligned plasma density irregularities and can be useful for wave diagnostics in laboratory and space plasmas.
State feedback control for adjusting the dynamic behavior of a piezoactuated bimorph atomic force microscopy probe
Authors: Orun Bilal , Necipoglu Serkan , Basdogan Cagatay , Guvenc Levent
Published: June 2009

We adjust the transient dynamics of a piezoactuated bimorph atomic force microscopy (AFM) probe using a state feedback controller. This approach enables us to adjust the quality factor and the resonance frequency of the probe simultaneously. First, we first investigate the effect of feedback gains on dynamic response of the probe and then show that the time constant of the probe can be reduced by reducing its quality factor and/or increasing its resonance frequency to reduce the scan error in tapping mode AFM.
The persistence length of double stranded DNA determined using dark field tethered particle motion
Authors: Brinkers Sanneke , Dietrich Heidelinde R. C. , de Groote Frederik H. , Young Ian T. , Rieger Bernd
Published: June 2009

The wormlike chain model describes the micromechanics of semiflexible polymers by introducing the persistence length. We propose a method of measuring the persistence length of DNA in a controllable near-native environment. Using a dark field microscope, the projected positions of a gold nanoparticle undergoing constrained Brownian motion are captured. The nanoparticle is tethered to a substrate using a single double stranded DNA (dsDNA) molecule and immersed in buffer. No force is exerted on the DNA. We carried out Monte Carlo simulations of the experiment, which give insight into the micromechanics of the DNA and can be used to interpret the motion of the nanoparticle. Our simulations and experiments demonstrate that, unlike other similar experiments, the use of nanometer instead of micrometer sized particles causes particle-substrate and particle-DNA interactions to be of negligible effect on the position distribution of the particle. We also show that the persistence length of the tethering DNA can be estimated with a statistical error of 2 nm, by comparing the statistics of the projected position distribution of the nanoparticle to the Monte Carlo simulations. The persistence lengths of 45 single molecules of four different lengths of dsDNA were measured under the same environmental conditions at high salt concentration. The persistence lengths we found had a mean value of 35 nm (standard error of 2.8 nm), which compares well to previously found values using similar salt concentrations. Our method can be used to directly study the effect of the environmental conditions (e.g., buffer and temperature) on the persistence length.
Strong temperature dependence of water reorientation in hydrophobic hydration shells
Authors: Petersen C. , Tielrooij K.-J. , Bakker H. J.
Published: June 2009

We study the temperature dependence of the orientational mobility of water molecules solvating hydrophobic molecular groups with femtosecond midinfrared spectroscopy. We observe that these dynamics show a strong temperature dependence. At temperatures <30° C the solvating water molecules show a reorientation time >10 ps, which is more than four times slower than in bulk water. With increasing temperature, the reorientation of the solvating molecules strongly accelerates and becomes much more equal to the reorientation rate of the molecules in the bulk liquid. These observations indicate that water molecules form relatively rigid solvation structures around hydrophobic molecular groups that melt at elevated temperatures.
String field theory-inspired algebraic structures in gauge theories
Authors: Zeitlin Anton M.
Published: June 2009

We consider gauge theories in a string field theory-inspired formalism. The constructed algebraic operations lead, in particular, to homotopy algebras of the related Batalin-Vilkovisky theories. We discuss an invariant description of the gauge fixing procedure and special algebraic features of gauge theories coupled to matter fields.