bluuebunny/crossref_metadata_2025 huggingface dataset:
Overcoming biological barriers to in vivo efficacy of antisense oligonucleotides
Authors: White Paul J. , Anastasopoulos Frank , Pouton Colin W. , Boyd Ben J.
Published: March 2009

Antisense oligonucleotides as a therapeutic platform have been slow to progress since the approval of the first antisense drug in 1998. Recently, there have been several examples of convincing antisense interventions in animal models and promising clinical trial data. This review considers the factors determining the success of antisense oligonucleotides as therapeutic agents. In order to produce target knockdown after systemic delivery, antisense oligonucleotides must avoid nuclease degradation, reticuloendothelial-system uptake and rapid renal excretion, and extravasate to the target cell type outside the vasculature. They then must enter the target cell, and escape the endosome–lysosome pathway so as to be free to interact with the target mRNA. We consider the significance of these limiting factors based on the literature and our own experience using systemic administration of antisense oligonucleotides.
THE EXAMINED LIFE?
Authors: Braddock Glenn
Published: March 2009

An introductory course in philosophy begins with Plato's Apology. Here Socrates famously states that ‘the unexamined life is not worth living for man’. The professor lingers on the idea. In this first week of the course they have already struck upon a justification for all of the torturous analyzing, arguing, and thought-experimenting that will follow in the next few months. Without these vehicles of ‘examination’, our lives are not worth living! The students may have experienced enthusiastic defenses of the value of academic disciplines from other professors, but this guy is selling the idea that philosophy is necessary for a meaningful life.
EPISTEMIC VAGUENESS?
Authors: Ablondi Fred
Published: March 2009

The barn/barn façade thought experiment is familiar to most epistemologists. It is intended to present a counterexample to certain causal theories of knowledge; in it, a father driving through the countryside with his son says, ‘That's a barn’ while pointing to a barn. Unbeknownst to the father, however, a film crew is working in the area, and it has constructed several barn façades. While the father did correctly point to a barn when he made his assertion, he could have just as easily pointed to a barn façade, and so, many hold, he does not know that the structure at which he is pointing is in fact a barn. If this is so, then it follows that true beliefs formed from reliable causal processes (in this case, vision by a competent observer under normal conditions) may still not qualify as knowledge.
MORAL RESPONSIBILITY FOR HARMING ANIMALS
Authors: Hadley John
Published: March 2009

Third-party intervention has been the focus of recent debate in self-defense theory. When is it permissible for third-parties to intervene on behalf of an innocent victim facing an unjustified attack or threat? In line with recent self-defense theory, if an attacker is morally responsible for their actions and does not have an acceptable excuse then it is permissible for third-parties to use proportionate violence against them.
MORAL DILEMMAS
Authors: Sainsbury Mark
Published: March 2009

Could it be that one morally ought to do something morally bad? Some people think the answer is obviously ‘No’. Indeed, these theorists may say, it is contradictory to suppose that one morally ought to do something morally bad. Others hold that it is not a contradiction but a sad fact of life that one may be morally required to do something morally bad. This latter position is the one I'll be supporting. If it's the right view, it really matters in practical affairs. For example, almost everyone would agree that it's morally bad to kill an innocent fetus. But this does not settle the question of whether one morally ought to have an abortion, if it can be morally required that one do something morally bad.
THE PROBLEM OF EVIL AND THE POVERTY OF THE FREE WILL THEODICY
Authors: Vroman Brian
Published: March 2009

The Problem of Evil, as it is typically called, is the strongest argument against the existence of a Deity who is at once all-powerful, all-knowing, kind and loving, and whose reach extends everywhere. Simply stated, the existence of such a being is incompatible with the existence of evil and suffering in the world. We know that evil and suffering exist; thus a Deity such as that described above cannot exist.
DEGREES OF PROPERTY
Authors: Neumann Michael
Published: March 2009

Sometimes people wonder why we should look at the morality of property at all. Property rights are taken to be legal constructs. Their validity rests, as Hume suggested, on their utility. In this context it makes little sense to focus on the specific provisions of property law and ask about their moral foundation. What has a foundation in morality is the whole system of property itself: laws, distributions, expectations, conventions. And the general usefulness of this arrangement is so large a question, so fraught with uncertainty, that it is almost beyond serious discussion.
A three‐dimensional numerical simulation of spreading umbrella clouds
Authors: Suzuki Y. J. , Koyaguchi T.
Published: March 2009

During explosive volcanic eruptions, an eruption column buoyantly rises as a turbulent plume, and an umbrella cloud spreads laterally as a gravity current at the neutral buoyancy level. The source conditions of explosive eruptions such as mass discharge rates of magma at vents have been estimated from the field observations (e.g., satellite images) on the height of the eruption columns and the spreading rate of umbrella clouds on the basis of the one‐dimensional (1‐D) plume model and the gravity current model. However, these simplified models contain empirical constants (entrainment coefficient of turbulent plume, k, and Froude number of gravity current, λ) that should be justified. We developed a time‐dependent three‐dimensional (3‐D) numerical model of eruption clouds to independently determine the values of these constants. The 3‐D model is designed to calculate quantitative features of turbulent mixing between an eruption cloud and the ambient air without any a priori empirical constants by applying a sufficiently fine grid size with a third‐order accuracy scheme. It has reproduced the fundamental features of eruption clouds including eruption columns, pyroclastic flows, coignimbrite ash clouds, and umbrella clouds. The altitudes of the spreading umbrella clouds in the 3‐D simulations are consistent with those of the neutral buoyancy level of eruption columns estimated by the 1‐D plume model with the entrainment coefficient k ∼ 0.1. The relationship between the volumetric flow rate and the spreading rate of the umbrella cloud in the 3‐D simulations is explained by the axisymmetrical gravity current model with λ ∼ 0.2 for eruption clouds in the tropical atmosphere and λ ∼ 0.1 for those in the midlatitude atmosphere. On the other hand, the total column height in the 3‐D simulations strongly oscillates even for a constant mass discharge rate, and its time average tends to be substantially greater than the column height estimated by the 1‐D plume model with k ∼ 0.1, particularly for large‐scale eruption clouds in the midlatitude atmosphere. We recommend a method to estimate the mass discharge rate from the observation of the column height or the spreading rate of umbrella cloud. The method and the accuracy of the 3‐D simulations are tested on the basis of the field data (e.g., the total height of the eruption column, the altitude and the spreading rate of the umbrella cloud, and the mass discharge rate) of the Pinatubo 1991 eruption.
Physical properties of subducted slab and surrounding mantle in the Izu‐Bonin subduction zone based on Broadband Ocean Bottom Seismometer data
Authors: Shito Azusa , Shiobara Hajime , Sugioka Hiroko , Ito Aki , Takei Yasuko , Kawakatsu Hitoshi , Kanazawa Toshihiko
Published: March 2009

Seismic attenuation and traveltime anomalies in the vicinity of the Izu‐Bonin subduction zone are inferred from waveform data recorded by Broadband Ocean Bottom Seismometers (BBOBSs) deployed as part of the Stagnant Slab Project. We measure the path‐averaged attenuation of P waves and traveltime anomalies of both P and S waves using waveform data from 10 regional earthquakes within the Izu‐Bonin slab. The observed relation between the attenuation and traveltime anomalies is quantitatively evaluated on the basis of mineral physics. For the data that sample the slab and the Pacific mantle beneath the slab, the relation between the attenuation and traveltime anomalies is consistent with predictions based on the thermal effect. The data that sample the mantle wedge show pronounced positive traveltime anomalies unaccompanied by comparable high attenuation. The traveltime anomalies are too intense to be explained solely in terms of the temperature effect. The temperature anomalies estimated from attenuation suggest that the temperature in the mantle wedge reaches the dry solidus of peridotite. The relative intensity of S to P wave traveltime anomalies of mantle wedge data, after correction for the thermal effect, is relatively small (RS/P = 0.5–1.2). Similarly low‐velocity anomalies without comparable high attenuation and with relatively small RS/P (<1.5) have been reported in previous studies of subduction zones at Tonga, in the southwest Pacific, and Tohoku, Japan. We discuss to what extent the present seismological observations can be explained by partial melt on the basis of recent theoretical and experimental studies on partially molten rocks.
Miocene‐Pliocene exhumation along the west Salton detachment fault, southern California, from (U‐Th)/He thermochronometry of apatite and zircon
Authors: Shirvell Catherine R. , Stockli Daniel F. , Axen Gary J. , Grove Marty
Published: March 2009

The Salton Trough is the northernmost segment of the active Gulf of California oblique rift system. The main rift‐related structure in the western Salton Trough is the low‐angle west Salton detachment fault (WSDF). Footwall and hanging wall apatite and zircon (U‐Th)/He ages record a significant contrast in thermal history across the WSDF, confirming Pliocene normal slip along the fault. Apatite (U‐Th)/He ages record rapid exhumational cooling from ∼5 to ∼2 Ma, consistent with the timing of accelerated tectonic subsidence recorded in WSDF hanging wall sedimentary strata and consistent with the initiation age of dextral plate boundary slip on the southern San Andreas fault in the Salton Trough. Our results indicate that the WSDF caused at least 2.3–4 km of exhumation and >8–10 km of approximately E directed horizontal extension since ∼5 Ma. Slip rate of the WSDF at Yaqui Ridge was likely in the range of ∼2.3–5 km/Ma from ∼7 to ∼2 Ma. The WSDF may have been active well before ∼5 Ma. Middle Miocene apatite (U‐Th)/He ages from samples at high elevations have steep age‐elevation gradients and suggest that exhumation may have initiated by ∼12 Ma, about when subduction ceased along a large segment of the Baja California margin and consistent with the age of onset of extension in northeastern Baja California.
Fluxes of soot black carbon to South Atlantic sediments
Authors: Lohmann Rainer , Bollinger Kevyn , Cantwell Mark , Feichter Johann , Fischer‐Bruns Irene , Zabel Matthias
Published: March 2009

Deep sea sediment samples from the South Atlantic Ocean were analyzed for soot black carbon (BC), total organic carbon (TOC), stable carbon isotope ratios (δ13C), and polycyclic aromatic hydrocarbons (PAHs). Soot BC was present at low concentrations (0.04–0.17% dry weight), but accounted for 3–35% of TOC. Fluxes of soot BC were calculated on the basis of known sedimentation rates and ranged from 0.5 to 7.8 μg cm−2 a−1, with higher fluxes near Africa compared to South America. Values of δ13C indicated a marine origin for the organic carbon but terrestrial sources for the soot BC. PAH ratios implied a pyrogenic origin for most samples and possibly a predominance of traffic emissions over wood burning off the African coast. A coupled ocean‐atmosphere‐aerosol‐climate model was used to determine fluxes of BC from 1860 to 2000 to the South Atlantic. Model simulation and measurements both yielded higher soot BC fluxes off the African coast and lower fluxes off the South American coast; however, measured sedimentary soot BC fluxes exceeded simulated values by ∼1 μg cm−2 a−1 on average (within a factor of 2–4). For the sediments off the African coast, soot BC delivery from the Congo River could possibly explain the higher flux rates, but no elevated soot BC fluxes were detected in the Amazon River basin. In total, fluxes of soot BC to the South Atlantic were ∼480–700 Gg a−1 in deep sea sediments. Our results suggest that attempts to construct a global mass balance of BC should include estimates of the atmospheric deposition of BC.
Ducted whistlers propagating in higher‐order guided mode and recorded on board of Compass‐2 satellite by the advanced Signal Analyzer and Sampler 2
Authors: Ferencz Orsolya E. , Bodnár László , Ferencz Csaba , Hamar Dániel , Lichtenberger János , Steinbach Péter , Korepanov Valery , Mikhaylova Galina , Mikhaylov Yuri , Kuznetsov Vladimir
Published: March 2009

The advanced electromagnetic wave detector and analyzer, Signal Analyzer and Sampler 2, successfully operated on board of Compass‐2 satellite (launched May 2006). One of the peculiarities of this experiment was that the efficient sensitivities of both electric and magnetic channels were very close to being identical. Between the interesting events detected we found the evidence of whistler mode signals propagating in higher‐ (third‐) order guided mode, most probable between two layers (i.e., “onionskin” structure was in the plasmasphere at this time). We present in the paper the real full wave ultrawideband interpretation of these propagating signals using the exact solution of Maxwell's equations in this boundary problem.
Scaling and paleodepth of compaction bands, Nevada and Utah
Authors: Schultz Richard A.
Published: March 2009

Measurements of the lengths and thicknesses of compaction bands in Navajo Sandstone from the Buckskin Gulch, Utah, field site demonstrate displacement‐length scaling with a power law exponent of ∼0.5, consistent with previous values obtained independently for compaction bands from the Valley of Fire, southern Nevada, site. Compaction energies calculated in this paper for the Utah bands, Gc = 55–120 kJ/m2, and for the Nevada bands, Gc = 30–60 kJ/m2, are consistent with those estimated from laboratory experiments despite major differences in band length, thickness, degree of grain fracturing, and remote stress state. Using the field measurements of bands from both sites in the recently proposed inverse relation between the magnitude of remote band‐normal compression and compaction band thickness predicts values of band‐normal compression of 24–30 MPa for the Utah bands and 31–62 MPa for the Nevada bands. Given that compaction bands at both sites are steeply dipping, these values correspond to a regional tectonic compression oriented subhorizontally at the time of band growth. The results suggest that the compaction bands formed at relatively shallow paleodepths of 0.92–1.3 km at the Utah site and 0.54–1.1 km at the Nevada site, in accord with estimates of the thickness of overlying stratigraphic cover during Sevier‐Laramide deformation at both sites. Growth of compaction bands at both field sites was likely facilitated by favorable host rock properties (well‐sorted, coarse‐grained, high‐porosity sandstone sequences) deformed within a thrust faulting tectonic environment.
Observation and origin of an interannual salinity anomaly in the Mozambique Channel
Authors: van der Werf P. M. , Schouten M. W. , van Leeuwen P. J. , Ridderinkhof H. , de Ruijter W. P. M.
Published: March 2009

A positive salinity anomaly of 0.2 PSU was observed between 50 and 200 m over the years 2000–2001 across the Mozambique Channel at a section at 17°S which was repeated in 2003, 2005, 2006, and 2008. Meanwhile, a moored array is continued from 2003 to 2008. This anomaly was most distinct showing an interannual but nonseasonal variation. The possible origin of the anomaly is investigated using output from three ocean general circulation models (Estimating the Circulation and Climate of the Ocean, Ocean Circulation and Climate Advanced Modeling, and Parallel Ocean Program). The most probable mechanism for the salinity anomaly is the anomalous inflow of subtropical waters caused by a weakening of the northern part of the South Equatorial Current by weaker trade winds. This mechanism was found in all three numerical models. In addition, the numerical models indicate a possible salinization of one of the source water masses to the Mozambique Channel as an additional cause of the anomaly. The anomaly propagated southward into the Agulhas Current and northward along the African coast.
Source of the 2007 Ist meteotsunami (Adriatic Sea)
Authors: Šepić Jadranka , Vilibić Ivica , Belušić Danijel
Published: March 2009

Široka Bay on the island of Ist in the northern Adriatic was struck by a severe inundation around 1530 UTC on 22 August 2007. The maximum wave height reached 4 m, and substantial material damage was induced. This paper investigates the generating force of the inundation. Data analysis indicates that the inundation was provoked through a double resonance mechanism, with initiation by a pronounced atmospheric disturbance that generated open ocean waves through the Proudman resonance. The waves were then further amplified inside the affected bay. The air pressure disturbance, which propagated at a speed of about 21–24 m s−1 over the northern Adriatic shelf, was investigated through both data analysis and atmospheric numerical modeling. Apparently, the air pressure disturbance was a surface manifestation of a ducted gravity wave, which propagated through the atmosphere from the Apennines to the eastern Adriatic coast over the northern Adriatic. According to the model simulation, the wave was trapped in a stable layer adjacent to the ground, which was capped by a dynamically unstable layer with wind speeds of about 22 m s−1. This made the unstable layer also a critical layer for gravity waves propagating with the same speed and allowed for their ducting in the layer below.
Determination of surface flow paths from gridded elevation data
Authors: Orlandini Stefano , Moretti Giovanni
Published: March 2009

Surface flow paths are obtained from gridded elevation data by connecting grid cell centers along predetermined flow directions. These flow directions are commonly determined using single and multiple flow direction algorithms. It remains, however, unclear whether multiple flow direction algorithms, which introduce artificial dispersion, can be used to describe surface flow paths and gravity‐driven processes across a terrain without causing unrealistic flow dispersion. To explore this issue, a unified algorithm for the determination of flow directions has been developed, and new methods for the validation of the resulting surface flow paths are introduced. The unified algorithm makes it possible, by setting appropriate parameters, to perform local or path‐based analyses and to experiment with different combinations of single and multiple flow directions in a morphologically significant manner. The new validation methods use drainage systems delineated from contour elevation data as a reference and take into consideration the overlap between these systems and those obtained from gridded elevation data. The unified algorithm is presented, and the results are evaluated for selected case studies in order to provide guidance on the use of surface flow path algorithms based on gridded elevation data.
Behavior of a shallow water table under periodic flow conditions
Authors: Cartwright Nick , Nielsen Peter , Perrochet Pierre
Published: March 2009

A new laboratory data set on the behavior of a shallow water table in a sand column aquifer subject to simple harmonic periodic forcing at its base is presented and discussed. The data are analyzed using the dynamic effective porosity, which is defined as the ratio of the rate of change in total moisture to the rate of change in water table elevation; thus, a reduction in this parameter means that the extent of moisture exchange has been reduced relative to a given water table fluctuation. The data show a clear decrease in the dynamic effective porosity with increasing proximity of the water table to the sand surface, which is consistent with previous research under a steadily rising or falling shallow water table. The observed reduction in moisture exchange due to shallowness of the water table has implications for periodic flow scenarios such as the propagation of water table waves in coastal and beach groundwater systems. That is, as moisture exchange is reduced, less work is being done by the flow, and thus, energy dissipation rates for shallow water tables will be reduced relative to the case of a deeper water table. At present no account of the influence of water table shallowness has been included in theories describing water table wave dispersion. The present experiments, in conjunction with the dynamic effective porosity concept, provide a framework in which this gap in knowledge can be further investigated. Additional experiments were designed such that the free surface transgressed the sand surface for part of the oscillation period to investigate the influence of meniscus formation and deformation at the sand surface on periodic flow dynamics. The observed behavior is consistent with previous observations of steady infiltration above shallow water tables, namely, a rapid drop (rise) in pore pressure with the onset of meniscus formation (deformation). A simple “wetting and drying” model is derived, accounting for the variation in effective porosity caused by the free surface transgressing the sand surface, which is shown to accurately capture the observed behavior. A finite element solution of the Richards equation in which the transient upper boundary condition is easily mimicked by means of a surface element with special storage features also shows excellent agreement with the observed data.
Triton X-100 promotes a cholesterol-dependent condensation of the plasma membrane
Authors: Ingelmo-Torres Mercedes , Gaus Katharina , Herms Albert , González-Moreno Elena , Kassan Adam , Bosch Marta , Grewal Thomas , Tebar Francesc , Enrich Carlos , Pol Albert
Published: March 2009

The molecular components of membrane rafts are frequently defined by their biochemical partitioning into detergent-resistant membranes. In the present study, we used a combination of epifluorescence and two-photon microscopy to visualize and quantify whether this insolubility in detergent reflects a pre-existing organization of the PM (plasma membrane). We found that the treatment of cells with cold TX (Triton X-100) promotes a profound remodelling of the PM, including a rapid rearrangement of the glycosphingolipid GM1 and cholesterol into newly formed structures, only partial solubilization of fluid domains and the formation of condensed domains that cover 51% of the remaining membrane. TX does not appear to induce the coalescence of pre-existing domains; instead, the domains that remain after TX treatment seem to be newly formed with a higher degree of condensation than those observed in native membranes. However, when cholesterol was complexed physically by treatment with a second detergent, such as saponin, cholesterol did not separate into the newly formed structures, condensation of the domains was unaltered, and the relative area corresponding to ordered domains increased to occupy 62% of the remaining membrane. Our results suggest that detergent can be used to enrich ordered domains for biochemical analysis, but that TX treatment alone substantially alters the lateral organization of the PM.
RNA helicase A acts as a bridging factor linking nuclear β-actin with RNA polymerase II
Authors: Tang Wen , You Wanhui , Shi Feng , Qi Tianyang , Wang Ling , Djouder Zina , Liu Wenguang , Zeng Xianlu
Published: March 2009

Actin, the major component of the cytoplasmic skeleton, has been shown to exist in the nucleus. Nuclear actin functions in several steps of the transcription process, including chromatin remodelling and transcription initiation and elongation. However, as a part of PICs (pre-initiation complexes), the role of actin remains to be elucidated. In the present study, we identified RHA (RNA helicase A) as an actin-interacting protein in PICs. Using immunoprecipitation and immunofluorescence techniques, we have shown that RHA associates with β-actin in the nucleus. A GST (glutathione transferase) pulldown assay using different deletion mutants revealed that the RGG (Arg-Gly-Gly) region of RHA was responsible for the interaction with β-actin, and this dominant-negative mutant reduced the recruitment of Pol II (RNA polymerase II) into PICs. Moreover, overexpression or depletion of RHA could influence the interaction of Pol II with β-actin and β-actin-involved gene transcription regulation. These results suggest that RHA acts as a bridging factor linking nuclear β-actin with Pol II.
Sentence Combining: Assessment and Intervention Applications
Authors: Scott Cheryl M. , Nelson Nickola Wolf
Published: March 2009

Clinicians can use sentence combining tasks to assess students' written language needs in the area of syntax and also as a context for language intervention. In this brief article, we describe current efforts to develop a formal standardized measure of written syntactic development and offer suggestions for using sentence combining as a context for intervention targeting higher level syntactic complexity.
Field induced by an axial magnetic dipole in the presence of two fused superconducting spheres: Analytic solution
Authors: Palaniappan D.
Published: March 2009

An exact solution for a magnetostatic boundary value problem involving two fused (overlapping) spheres placed in a field generated by an axial magnetic point dipole is constructed based on the image method. The basic idea is illustrated for two unequal superconducting spheres intersecting with a vertex angle π/2 and the analytical solution for the scalar magnetic potential satisfying the Neumann boundary condition at the surface is derived. The image solution for a dipole-twin-sphere configuration consists of three image dipoles—one inside each sphere and the third inside a pseudo-/virtual sphere—all located at the respective inverse points inside the superconducting two-sphere assembly. The levitation force acting on the two-sphere superconducting surface is also calculated for the overlapping geometry. These exact results can be used as a benchmark for testing numerical algorithms for overlapping spherical superconductors. Our simple approach also offers clues for solving the Neumann boundary value problem for vertex angles π/n, n is an integer, and other related superconducting geometries.
Electronic structures and magnetic properties of the compounds Cen+1Co3n+5B2n (n=0, 1, 2, and ∞)
Authors: Ito T. , Ido H.
Published: March 2009

Electronic structures of Cen+1Co3n+5B2n compounds with n=0, 1, 2, and ∞ have been calculated and the magnetic moments of Co and Ce atoms at the respective crystallographic sites have been determined. General features of local density of states for Co atoms in Cen+1Co3n+5B2n are found to be similar to those in Yn+1Co3n+5B2n. It is found that magnetic moments of Ce atoms are not negligible and in opposite direction to the Co-sublattice magnetization in Cen+1Co3n+5B2n with n=0, 1, and 2. The CeCo3B2 compound is found to be nonmagnetic. Calculated magnetic moments in Ce3Co11B4 are in fairly good agreement with neutron diffraction data. Calculated results are also used to explain some experimental data.
Effect of temperature and vacuum on the magnetic properties and compositional changes in high temperature Sm–Co magnets
Authors: Liu J. F. , Marinescu M. , Vora P. , Wu S. X. , Harmer M. P.
Published: March 2009

Electric propulsion systems for space exploration require materials and components that can perform reliably under a vacuum of 10−5 Torr and at temperatures of over 400 °C. Scanning electron microscopy analysis shows that when Sm–Co magnets are exposed to temperatures up to 550 °C for up to 240 h in a vacuum of 10−5 Torr, the surface alteration is morphologically similar to oxidation in air. However, the scale of the affected region is much smaller and consists of about 1–2 μm of a top outermost Sm-depleted oxide layer and about 10–20 μm of a more complex layer in which the constituent atoms redistribute with oxygen penetration. No excessive Sm depletion was observed in the second layer. For all Sm–Co magnet samples, the maximum energy product decreased by less than 10% even at temperatures of 100 °C above their specified maximum operating temperature TM. The residual induction of the magnets with TM=550 °C decreased by 8.5% after baking at 700 °C under vacuum for 240 h.
Incorporating core hysteresis properties in three-dimensional computations of transformer inrush current forces
Authors: Adly A. A. , Hanafy H. H.
Published: March 2009

It is well known that transformer inrush currents depend upon the core properties, residual flux, switching instant, and the overall circuit parameters. Large transient inrush currents introduce abnormal electromagnetic forces which may destroy the transformer windings. This paper presents an approach through which core hysteresis may be incorporated in three-dimensional computations of transformer inrush current forces. Details of the approach, measurements, and simulations for a shell-type transformer are given in the paper.
Gigahertz frequency tunable noise suppressor using nickel nanorod arrays and Permalloy films
Authors: Kuanr Bijoy K. , Marson Ryan , Mishra Sanjay R. , Kuanr Alka V. , Camley R. E. , Celinski Z. J.
Published: March 2009

To suppress noise in electronic devices at gigahertz frequencies, the signal attenuation in the pass-band frequency region must be minimized to enhance the signal integrity without distortion. We designed, fabricated, and evaluated two noise suppression microstructures, one using nickel nanorod arrays in a porous anodic aluminum oxide dielectric and a second structure based on a Ni80Fe20 (Permalloy) film in a microstrip waveguide geometry. Both noise suppression structures function as tunable devices in the microwave range. The devices show signal attenuation at the resonance frequency which is increased more than −20 dB compared with a microstrip line without any magnetic material. At ferromagnetic resonance the power loss in the nanorod structure was 15% higher than that of a Permalloy based device. In the pass-band frequency region the signal attenuation/insertion loss of the nanorod arrays was about 2 dB higher than that of the Permalloy film. It is observed that to get good noise suppression, the signal distortion due to the signal phase shift must also be minimized. The differential phase shift of the Ni nanorod device was ∼20% smaller than that of the Permalloy film device. We also designed noise suppressors using Ni nanorods by changing aspect ratios (rod lengths of 5–50 μm and diameter of 200 nm). The noise suppression frequency and the magnitude of signal attenuation in the noise suppressor were increased as the Py element became thicker.
Investigation of an effective anisotropy field involved in photoinduced precession of magnetization in (Ga,Mn)As
Authors: Kobayashi S. , Hashimoto Y. , Munekata H.
Published: March 2009

Photoinduced precession of magnetization in (Ga,Mn)As was studied for a wide range of Mn contents (0.01≤x≤0.11) by time-resolved magneto-optical measurements. It was found that an effective anisotropy field decreases with increasing Mn contents. Anisotropy fields were also extracted from photoinduced precession measured at different temperatures and compared with magnetization. Significant enhancement in the amplitude of oscillation in magneto-optical signals occurred with increasing pump power. The mechanism of a change in the anisotropy field with the pump power was discussed.
On polynomial invariants of several qubits
Authors: Ðoković D. Ž. , Osterloh A.
Published: March 2009

It is a recent observation that entanglement classification for qubits is closely related to local SL(2,C)-invariants including the invariance under qubit permutations [Dür, et al., Phys. Rev. A 62, 062314 (2000); Osterloh, A. and Siewert, J., Phys. Rev. A 72, 012337 (2005); O. Chterental and D. Ž. Ðoković, Linear Algebra Research Advances (Nova Science, Hauppauge, N.Y., 2007), Chap. 4, p. 133], which has been termed SL∗ invariance. In order to single out the SL∗ invariants, we analyze the SL(2,C)-invariants of four (five) qubits and decompose them into irreducible modules for the symmetric group S4 (S5) of qubit permutations. A classifying set of measures of genuine multipartite entanglement is given by the ideal of the algebra of SL∗-invariants vanishing on arbitrary product states. We find that low degree homogeneous components of this ideal can be constructed in full by using the approach introduced by Osterloh and Siewert [Phys. Rev. A 72, 012337 (2005); Int. J. Quant. Inf. 4, 531 (2006)]. Our analysis highlights an intimate connection between this latter procedure and the standard methods to create invariants, such as the Ω-process [Luque, J.-G. and Thibon, J.-Y., J. Phys. A 39, 371 (2005)]. As the degrees of invariants increase, the alternative method proves to be particularly efficient.
Room temperature ferromagnetism of Cu doped ZnO nanowire arrays
Authors: Gao Daqiang , Xu Yan , Zhang Zhaohui , Gao Hua , Xue Desheng
Published: March 2009

We report the room temperature ferromagnetism of Cu doped ZnO nanowire arrays embedded in anodic aluminum oxide template. The nanowires about 100 nm in diameter were fabricated by electrodepositing Zn2+ and Cu2+ into the template and postoxidation annealing in air atmosphere. Magnetization measurements indicated that the Zn1−xCuxO (x=0.05 and 0.07) nanowires exhibit room temperature ferromagnetism and the Zn0.93Cu0.07O nanowires annealed in vacuum reveals an enhancement of the ferromagnetism. X-ray diffraction pattern, x-ray photoelectron spectroscopy, and Raman spectra measurements showed that all the samples possess a typical wurtzite structure and no other impurity phases were observed.
Quasi-isentropic compression using functionally graded materials in gas gun and explosive driven systems
Authors: Ray Aditi , Menon S. V. G.
Published: March 2009

Results of hydrodynamic simulations of dynamic compression experiments performed by impact loading of materials are reported. The simulations pertain to a new approach for generating quasi-isentropic compression using functionally graded materials (FGM). First of all, we focus on quasi-isentropic compression waves generated by a constant velocity impactor (similar to that from a gas gun). Quasi-isentropic compression is characterized from the temporal profiles of pressure at target surface and fluid velocity at target-window interface generated from different functional forms of density variation along the FGM flyer. It is shown that quadratic FGM is the best option for increasing rise time of pressure pulse. Secondly, FGM induced quasi-isentropic compressions are studied by accelerating the impactor with high explosive (HE) driven shocks in both the cases when impactor is in contact with the target (contact geometry) and separated from target by air gap (flyer geometry). The study reveals that nearly isentropic pressure profiles can be realized with quadratic FGM impactor in flyer geometry. Contact geometry produces a distinct initial pressure jump which is undesirable for isentropic compression. Finally, quasi-isentropic compressions are observed for spherically symmetric FGM flyers driven by HE. Here also it is seen that quadratic FGM impactor serves better in improving the peak impact velocity at shell target. Thus, based on the study, we conclude that quadratic FGM is the right choice for generating quasi-isentropic compression. The parameters of the FGM impactors, optimized using a genetic algorithm code, are also presented for both planar and spherical systems.
The electronic structure of oxygen atom vacancy and hydroxyl impurity defects on titanium dioxide (110) surface
Authors: Minato Taketoshi , Sainoo Yasuyuki , Kim Yousoo , Kato Hiroyuki S. , Aika Ken-ichi , Kawai Maki , Zhao Jin , Petek Hrvoje , Huang Tian , He Wei , Wang Bing , Wang Zhuo , Zhao Yan , Yang Jinlong , Hou J. G.
Published: March 2009

Introducing a charge into a solid such as a metal oxide through chemical, electrical, or optical means can dramatically change its chemical or physical properties. To minimize its free energy, a lattice will distort in a material specific way to accommodate (screen) the Coulomb and exchange interactions presented by the excess charge. The carrier-lattice correlation in response to these interactions defines the spatial extent of the perturbing charge and can impart extraordinary physical and chemical properties such as superconductivity and catalytic activity. Here we investigate by experiment and theory the atomically resolved distribution of the excess charge created by a single oxygen atom vacancy and a hydroxyl (OH) impurity defects on rutile TiO2(110) surface. Contrary to the conventional model where the charge remains localized at the defect, scanning tunneling microscopy and density functional theory show it to be delocalized over multiple surrounding titanium atoms. The characteristic charge distribution controls the chemical, photocatalytic, and electronic properties of TiO2 surfaces.
Enhanced side-mode suppression in chaotic stadium microcavity lasers
Authors: Mestanza S. N. M. , Von Zuben A. A. , Frateschi N. C.
Published: March 2009

We report an enhanced side-mode suppression in Bunimovich stadium lasers with strained InGaAs/InGaP quantum well (QW) active regions. This is realized with spatially selective carrier injection along a particular periodic orbit of the stadium. The selectivity is achieved using He+3 ion implantation. Up to 21 dB enhancement in side-mode suppression is observed for a 40×20 μm2 stadium with interband transition between the first excited quantum well level. The improvement in side-mode suppression is apparently a consequence of coherent beating between orbits leading to a Vernier effect. A simple model corroborate with this hypothesis.
Structural characteristics of transition to turbulence in microscale capillaries
Authors: Natrajan V. K. , Christensen K. T.
Published: March 2009

The maturation of flow in microscale capillaries (D=536 μm) from a laminar to a turbulent state is studied via extensive microscopic particle image velocimetry measurements spanning the Reynolds-number range of 1900≤Re≤4500. Some previous studies of transition to turbulence in microscale passages have observed transition at anomalously low Re, leading to the suggestion that flow at these scales is fundamentally different from that at the macroscale. One possible culprit for these reports of early transition could be significant surface roughness in the microchannels employed. As such, care is taken in the present experiments to select microscale capillaries with minimal inner surface roughness in order to remove the possibility that roughness could trigger early transition. Consistent with transitional wall-bounded flows at the macroscale, transitional capillary flow is found to contain patches of increasingly disordered motion with increasing Re bounded by laminar flow behavior. The intensity and frequency of occurrence of these disordered motions grow with Re, and quadrant analysis supports a gradual maturation of the instantaneous Reynolds-shear-stress-producing events as the flow transitions toward a fully turbulent state. Proper orthogonal decomposition of the transitional data sets indicates that large-scale structures play a vital role in the transport of both kinetic energy as well as Reynolds-shear stress and visualization of these large-scale motions reveals spatial signatures consistent with hairpin vortex packets.
Global attractor for a class of Kirchhoff models
Authors: Zhijian Yang , Baoxia Jin
Published: March 2009

The paper studies the longtime behavior of solutions to the initial boundary value problem (IBVP) for a class of Kirchhoff models arising in elastoplastic flow utt−div{|∇u|m−1∇u}−Δut+Δ2u+h(ut)+g(u)=f(x). By combining the decomposition idea with the operate technique, it proves that under rather mild conditions, the dynamical system associated with above-mentioned IBVP possesses in different phase spaces a global attractor which is connected, respectively. For application, the fact shows that for the concerned elastoplastic flow the permanent regime (global attractor) can be observed when the excitation starts from any bounded set in phase space.
Influence of 211 particles on twin spacing in top-seeded melt-growth YBCO bulk superconductors
Authors: Diko P. , Šuster D.
Published: March 2009

Influence of Y211 particles on the structure of {110} twins in single-grain YBCO bulk superconductors was studied by polarization light optical microscopy on the surfaces with small declination from the {110} plane. Used conditions allowed the observation of twin structure and twin spacing measurements at the twin spacing below the resolution limit of optical microscopy. Obtained results show that the twin spacing is proportional to the square root of the mean free distance between Y211 particles present in the samples. It is also shown that the twin complex size can be enormously high under the influence of thermal residual stresses.
High temperature sodium ordering transition in NaxCoO2 studied by mechanical spectrum
Authors: Ying X. N. , Xu Z. C.
Published: March 2009

The mechanical spectrum of γ-NaxCoO2 above room temperature was measured using the vibrating reed method at kilohertz frequency. A sodium ordering transition around 427 K was previously deduced by the mechanical spectrum of Na0.66CoO2, which is annealed at 400 °C in the flowing oxygen gas. A step increase in modulus with the decrease in temperature was observed at this transition. Similar results have been observed in as-prepared and annealed Na0.62CoO2 samples around 430 K. However, modulus softening was observed around 385 K in as-prepared Na0.66CoO2, and the step increase in modulus with the decrease in temperature was observed around 345 K. The modulus softening is expected to be from a structural phase transition. This structural phase transition shifts the sodium ordering transition to 345 K in as-prepared Na0.66CoO2 system.
Invariant submanifold for series arrays of Josephson junctions
Authors: Marvel Seth A. , Strogatz Steven H.
Published: March 2009

We study the nonlinear dynamics of series arrays of Josephson junctions in the large-N limit, where N is the number of junctions in the array. The junctions are assumed to be identical, overdamped, driven by a constant bias current, and globally coupled through a common load. Previous simulations of such arrays revealed that their dynamics are remarkably simple, hinting at the presence of some hidden symmetry or other structure. These observations were later explained by the discovery of N−3 constants of motion, the choice of which confines the resulting flow in phase space to a low-dimensional invariant manifold. Here we show that the dimensionality can be reduced further by restricting attention to a special family of states recently identified by Ott and Antonsen. In geometric terms, the Ott–Antonsen ansatz corresponds to an invariant submanifold of dimension one less than that found earlier. We derive and analyze the flow on this submanifold for two special cases: an array with purely resistive loading and another with resistive-inductive-capacitive loading. Our results recover (and in some instances improve) earlier findings based on linearization arguments.
Theory of magnetoelectric effect for bending modes in magnetostrictive-piezoelectric bilayers
Authors: Petrov V. M. , Srinivasan G. , Bichurin M. I. , Galkina T. A.
Published: March 2009

In a magnetostrictive-piezoelectric bilayer the interaction between the magnetic and electric subsystems occurs through mechanical deformation. A model is discussed here for the resonance enhancement of such magnetoelectric (ME) interactions at frequencies corresponding to bending oscillations. The thickness dependence of stress, strain, and magnetic and electric fields within a sample are taken into account so that the bending deformations could be considered in an applied magnetic or electric field. The frequency dependence for longitudinal and transverse ME voltage coefficients have obtained by solving electrostatic, magnetostatic, and elastodynamic equations. We consider boundary conditions corresponding to bilayers that are free to vibrate at both ends, or simply supported at both ends, or fixed at one end. It is shown that the bending resonance and consequent enhancement in ME coupling occurs at the lowest frequency for a bilayer that is fixed at one end and free at the other end. The model is applied to a specific case of permendur-lead zinconate titanate bilayer. The theory is in very good agreement with representative data.
Charge separation in the conical meniscus of an electrospray of a very polar liquid: Its effect on the minimum flow rate
Authors: Higuera F. J.
Published: March 2009

An analysis is presented of the flow and the distribution of charge in the meniscus of an electrospray of a very polar liquid which is fed with a low flow rate. The shape of the meniscus is taken to be a Taylor cone. The characteristic value of the flow rate at which the liquid ceases to be quasineutral in a certain relaxation region of the conical meniscus under the action of the applied field is estimated, and the current/flow rate characteristic of the electrospray is numerically computed in these conditions. A state of complete charge separation, in which the ions that are pushed by the electric field away from the tip of the meniscus cease to reach the jet of the electrospray, is found for a finite value of the flow rate, and no stationary solution exists below this flow rate. For very polar liquids of small viscosity, this minimum flow rate is of the order of the experimental minimum for the cone-jet regime when the flux of the electric field in the jet is taken into account. The flow induced in the meniscus by the Coulomb force in the bulk of the liquid and the electric shear stress at its surface is computed and its effect on the distribution of charge and the minimum flow rate is analyzed. Estimates of the flow and the electric current in the jet are worked out for a range of flow rates above the minimum.
A kinetic model to study film deposition during dusty plasma chemical vapor deposition process
Authors: Rovagnati B. , Mashayek F.
Published: March 2009

A simplistic numerical kinetic model to predict the deposited film morphology in dusty plasma chemical vapor deposition reactors is developed. The morphological accretion of a circular object is studied in a two-dimensional geometry and the most important deposition phenomena are taken into account, i.e., surface diffusion and surface ion bombardment. Both isotropic and anisotropic plasmas are considered. It is shown that when the particle is located in an isotropic plasma, the deposited film maintains the original particle sphericity. Whereas, if the particle is assumed to levitate in the (pre) sheath forming around the bottom electrode of the reactor and ions contribute considerably to the deposition, the film develops in a nonuniform manner similar to experimental observations.