bluuebunny/crossref_metadata_2025 huggingface dataset:
THE EFFECT OF CEREBRAL ISCHEMIA ON THE ULTRASTRUCTURE OF THE HYPOTHALAMO‐NEURO‐HYPOPHYSIAL SYSTEM OF THE MONGOLIAN GERBIL. THE SUPRAOPTIC AND PARAVENTRICULAR NUCLEI
Authors: Loesch Andrzej
Published: August 2007

The results of ultrastructural studies of thc nucleus supraopticus (SON) and n. paraventricularis (PVN) of male mongolian gerbils subjected to experimental cerebral ischemia induced by 10 min bilateral occulsion of the common carotids are reported. Marked alterations concerned endocrine neurons. some neurosecretory axons and synaptic terminals as well as astroglia cells. Basing on the electron density of cytoplasmic ground, two varieties of endocrine neurons, that is ‘light’ and ‘intermediate’, were designated in both SON and PVN nuclei. These findings suggest that during cerebral ischemia the SON and PVN neurons become activated (Golgi complex and granular endoplasmic reliculum enlargement) and that they represent different phases of secretory cycle of a single cell type. However, in SON nucleus some neurons were probably damaged because they had the appearance of decidedly ‘dark’ cells. With respect to some neurosecretory axons, the finding of externally lying lamellar whorls indicates ischemic injury of the axons. Similar significance may be attributed to some synaptic terminals which showed an increased polymorphism of synaptic vesicles and vesicular aggregation. There was marked swelling of perivascular astroglia cells and change of their cytoplasm in both SON and PVN nuclei. Moreover, the swollen astroglia cells contacted those ‘dark’ neurons in SON nucleus. The present study indicates that SON and PVN nuclei are highly sensitive to application of cerebral ischemia. At the same time perivascular injury may suggest involvement of astroglia cells in the production of subsequent changes in the SON and PVN neuropil.
RECEPTOR‐MEDIATED 125I‐LABELLED INSULIN DEGRADATION IN THE RAT HEPATOCYTE. STUDIES USING CHLOROQUINE
Authors: Bonser Anne M , Garcia‐webb Peter , Bhagat Chotoo I
Published: August 2007

Degradation of insulin during incubation with target cells occurs via receptor‐mediated processes. In this study, receptor‐mediated degradation of 125I‐labelled insulin was investigated in rat hepatocytes, using the agent chloroquine.

Chloroquine increased specific cell‐associated 125I‐labelled insulin at 37°. The increased radioactivity with chloroquine was intracellular (53.3 ± 1.2% of initially bound label was displaced by excess cold insulin; in control cells 67.0±2.1 % was displaced. P<0.005). The effect of chloroquine was prevented by adding label at 15° or by pre‐treatment with 5 mM KCN, 5 mM NaN3 or 1 g/1 bacitracin, which indicated a post‐internalization site of action. Chloroquine had no effect on degradation of 125I‐labelled insulin in buffer alone or in buffer previously incubated with cells. Specific studies of receptor‐mediated degradation at 37° showed that more 125I‐labelled insulin remained associated with hepatocytes when chloroquine was present (P<0.0005 after 60 min). Analysis of chloroquine's effect on the intactness of 125I‐labelled insulin released during processing of surface‐bound label at 37° showed that chloroquine‐sensitive mechanisms accounted for at least 50% of receptor‐mediated insulin degradation in rat hepatocytes.
INTERACTIONS OF PROTEIN CALORIE MALNUTRITION, MALARIA INFECTION AND IMMUNE RESPONSES
Authors: Bhatia A , Aggarwal A , Sehgal S , Chakravarti RN , Vinayak VK
Published: August 2007

The course of parashaemia and certain immune responses in prolein or calorie‐deficient albino rats infected with Piasmodium berghei (NICD) were studied. Wide variations observed in the course of parasitaemia in protein‐deficient animals were (a) prolonged prepatent period, short patent period with low para‐silaemia (50% of animals), (b) short prepatent period and an inability to resolve the infection (14% of animals) and (c) no patent parasitaemia at any stage of observation (23. 5% of animals). The calorie‐deficienl animals had significantly lower parasitaemia (P<0.05) compared with well fed animals. Protein deficiency resulted in depression of T‐dependent immune responses in uninfected as well as P. berghei‐infected animals. The outcome of the parasitaemia in protein‐ as well as calorie‐deficient animals seems to be the combined result of deficiencies of certain essential nutrients, proteins and calories in the diet as well as the immune responses of the host.
THE LOCATION OF ANTIGENIC SITES ON THE SURFACE OF THE NEMATODE PARASITE STRONGYLOIDES RATTI REACTIVE TO ANTIBODY‐DIRECTED CELLULAR CYTOTOXICITY FROM BOTH MACROPHAGES AND EOSINOPHILS FROM THE NATURAL HOST
Authors: Tam ND , Papadimitriou J , Keast D
Published: August 2007

Heat‐treated and untreated sera from rats immune to Strongyloides ratti are capable of arming both immune and non‐immune macrophages and eosinophils in vitro. These cells are capable of killing larvae of the parasite. Electron microscopy has indicated multi‐point attachment of the cells to the epicuticular transverse grooves of the larvae within 4 and 24 h of incubation at 37°.
LYSOSOMAL ENZYMES IN THE SPLEEN OF ALBINO RATS, MICE AND MASTOMYS NATALENSIS DURING PLASMODIUM BERGHEI INFECTION
Authors: Saxena JK , Khare S , Srivastava AK , Sen AB , Ghatak S
Published: August 2007

Activities of certain acid hydrolases of the spleen were followed in three different rodents during the course of Plasmodium berghei infection. In albino rats where sterile immunity against the infection develops, the specific activities of a few acid hydrolases first declined then increased from day 7 and showed a several‐fold increase over control values when there were no detectable parasites in peripheral circulation. In contrast, in Mastomys natalensis and albino mice which succumb to infection the levels of these enzymes were reduced throughout the course of infection. These results indicate a close correlation between host resistance to infection and the level of lysosomal enzymes in spleen.
PANCREATIN‐EDTA TREATMENT AFFECTS BUOYANCY OF CELLS IN COHN FRACTION V PROTEIN DENSITY GRADIENTS WITHOUT RESIDUAL EFFECT ON CELL SIZE
Authors: Sheridan JW , Simmons RJ
Published: August 2007

The buoyancy of suspension‐grown Mastocytoma P815 X‐2 cells in albumin‐rich Cohn fraction V protein (CFVP) density gradients was found to be affected by prior incubation of the cells in pancreatin‐EDTA salt solution. Whereas in pH 5·2 CFVP, pancreatin‐EDTA treated cells behaved as if of reduced density when compared with the control ‘undigested’ group, in pH 7·3 CFVP they behaved as if of increased density. By contrast, pancreatin‐EDTA treatment had no effect on the buoyancy of mastocytoma cells in polyvinylpyrrolidone‐coated colloidal silica (PVP‐CS, Percoll T.M.) density gradients of either pH 5·2 or pH 7·3. As cell size determinations failed to reveal alterations in cell size either as a direct result of pancreatin‐EDTA treatment or as a combined consequence of such treatment and exposure to CFVP either with or without centrifugation, a mechanism involving a change in cell density other than during the centrifugation process itself seems unlikely. Binding studies employing 125I‐CFVP, although indicating that CFVP bound to cells at 4°, failed to reveal a pancreatin‐EDTA treatment‐related difference in the avidity of this binding. Although the mechanism of the pancreatin‐EDTA‐induced buoyancy shift in CFVP remains obscure, the absence of such an effect in PVP‐CS suggests that the latter cell separation solution may more accurately be used to determine cell density.
BINDING OF MURINE IgM AND MONOCLONAL IgM/A (κ) HYBRID ANTI‐TYPE III PNEUMOCOCCAL POLYSACCHARIDE (SIII) ANTIBODIES TO STAPHYLOCOCCAL PROTEIN A
Authors: Kearney R
Published: August 2007

Evidence is produced to show that two specific subclasses of IgM antibodies are formed during the primary immune response to Type III pneumococcal polysaccharide (SIII) in mice. The IgM proteins can be divided into two groups based on different reactivities with protein‐A. As with human IgM subclasses, it is proposed to call the two IgM subclasses IgM1 and IgM2, where the latter is defined by the ability to react with protein‐A of Staphylococcus aursus. Only the IgM molecule which reacted with protein‐A produced passive haemolysis in the presence of guinea‐pig complement. Results also show that the IgA anti‐SIII activity in serum of SIII‐immune mice on day 5 of the primary response is due lo hybrid IgM/A(κ) antibody which is undetected by conventional methods for enumerating antibody‐forming cells because cells producing IgM/A antibody develop direct plaques with guinea‐pig complement. A monoclonal IgM/A(κ) anti‐SIII produced from spleen cells 5 days after injection of 10 μg SIII plus pertussis vaccine exhibited similar properties to molecules with μ and α‐determinants in serum. The IgM/A hybrid antibody reacted strongly with protein‐A and produced passive haemolysis of SIII‐coated erythrocytes in the pretence of guinea‐pig, but not mouse, complement Despite its specificity for the capsular antigen of Type III pneumococci, the IgM/A hybrid antibody conferred only temporary immunity in mice challenged with viable pneumococci. The nature and properties of IgM/A antibodies as well as those of the subclasses of IgM may give important clues lo the genetic regulation and expression of antibody production. These findings may provide an explanation for some of the anomalies in various areas of immunological research.
Abundance and Composition of Zooplankton (Copepoda, Cladocera, Rotifera) in Lake Taal: Potential Impact of Intensive Size-Selective Predation by the Freshwater Sardine, Sardinella tawilis (Herre 1927)
Authors: Papa Rey Donne , Pagulayan Roberto , Pagulayan Alicia Ely
Published: August 2007

Zooplankton are considered to be important members of the lake ecosystem. The abundance and composition of which are due to several factors, for example, the impact of intensive size-selective predation by planktivorous fishes residing in the lake. In this study, the abundance and composition of zooplankton found in the vicinity of Isla Napayun - a known fishing ground of the freshwater sardine, Sardinella tawilis (Herre 1927) was analyzed using samples taken from vertical plankton tows from the 10 and 20 m depths in 2 sampling sites from the said area. These were then compared with the stomach contents of S. tawilis taken during the same period. Results show that there were 4 genera of Copepoda, 4 genera of Cladocera and 2 genera of Rotifera found in the plankton tows that were analyzed. Of these, the nauplius larvae of the copepods were noted to be the most abundant followed by the rotifer Brachionus spp. Analysis of the stomach contents of the collected S. tawilis samples revealed a zooplankton diet that was composed of 90% Copepoda with the remaining 10% being made up of the Cladocera and Rotifera. These results indicate that small-bodied organisms dominate the lake. This is indicative of intensive size-selective predation by the S. tawilis on the zooplankton population of the area. This is further validated by the high preference of S. tawilis for Copepoda, which is the largest of the 3 groups (in terms of size) in the samples that were analyzed in spite of the fact that small-bodied zooplankton dominate the zooplankton community during the entire sampling period. The zooplankton found in this particular area of Lake Taal has been observed to be highly influenced by intensive size selective preference of planktivores such as the S. tawilis for bigger zooplankton.
Car-Parrinello and path integral molecular dynamics study of the hydrogen bond in the chloroacetic acid dimer system
Authors: Durlak Piotr , Morrison Carole A. , Middlemiss Derek S. , Latajka Zdzislaw
Published: August 2007

We have studied the double proton transfer (DPT) reaction in the cyclic dimer of chloroacetic acid using both classical and path integral Car-Parrinello molecular dynamics. We also attempt to quantify the errors in the potential energy surface that arise from the use of a pure density functional. In the classical dynamics a clear reaction mechanism can be identified, where asynchronized DPT arises due to coupling between the O–H stretching oscillator and several low energy intermolecular vibrational modes. This mechanism is considerably altered when quantum tunneling is permitted in the simulation. The introduction of path integrals leads to considerable changes in the thermally averaged molecular geometry, leading to shorter and more centered hydrogen bond linkages.
Role of chain stiffness on the conformation of single polyelectrolytes in salt solutions
Authors: Wei Yu-Fu , Hsiao Pai-Yi
Published: August 2007

Conformation of single polyelectrolytes in tetravalent salt solutions is investigated under the framework of a coarse-grained model, using Langevin dynamics simulations. The chain size, studied by the radius of gyration, shows three different variational behaviors with salt concentration, depending on the chain stiffness. According to the size variations, polyelectrolytes of fixed chain length are classified into three categories: (1) flexible chain, for which the variation shows a curve similar to a tilted L, (2) semiflexible chain, whose curve resembles U, and (3) rigid chain, for which the curve is a straight line. The wormlike chain model with persistence length predicted by the Odijk-Skolnick-Fixman theory is found to be able to qualitatively describe the end-to-end distance at low salt concentration not only for semiflexible and rigid chains but also for flexible chain. In a low salt region, a flexible polyelectrolyte extends more significantly than a semiflexible chain, in reference of the size of their uncharged counterparts, and in a high salt region, regardless of chain stiffness, a chain attains a dimension comparable to that of its neutral polymer. The chain stiffness influences both the local and the global chain structures. A flexible chain exhibits a zigzagged local structure in the presence of salt ions, and the condensed structure is a disordered, random globule. A semiflexible chain is locally smooth, and the condensed structure is orderly packed, taking a form such as hairpin or toroid. Moreover, the chain stiffness can also affect the nature of the coil-globule transition. The transition occurred in a discrete manner for semiflexible chain, whereas it occurred in a continuous way for flexible chain. This discrete feature happened not only at low salt concentration when a semiflexible chain collapsed but also at high salt concentration when the collapsed chain is reexpanded. At the end, the effects of chain stiffness and salt concentration on the conformation of single polyelectrolytes are summarized in a schematic state diagram.
The formation of vibrationally excited HD from atomic recombination on cold graphite surfaces
Authors: Islam Farahjabeen , Latimer Elspeth R. , Price Stephen D.
Published: August 2007

HD molecules formed in v″=3 and v″=4 have been detected by laser spectroscopy when a cold (15K) graphite surface is irradiated with H and D atoms. Population of the v″=3, J″=0–6 and v″=4, J″=0–6 levels has been detected and the average rotational temperatures of the nascent HD were determined. These results are compared with previous data collected for the formation of HD in v″=1 and 2 under similar conditions. This comparison indicates that the nascent HD flux increases with increasing vibrational quantum number for v″=1–4.
Structure and magnetic properties of FePt∕B4C multilayer thin films: Role of the compositional elements intermixing
Authors: Zhou M. J. , Li Quan , Yang F. J. , Wang H. B. , Wang H. , Tang D.
Published: August 2007

Fe Pt ∕ B 4 C multilayer thin films were deposited using magnetron sputtering with different boron carbide layer thicknesses. Experimental results suggest that the B4C layers effectively serve as spacers to separate the FePt layers, making the multilayer configuration stable even after film annealing at elevated temperatures. On the other hand, B and C are found to incorporate into the FePt layer, which is responsible for the FePt grain growth confinement and grain separation, and eventually affects the magnetic properties of the composite film.
Instability and pattern formation in reaction-diffusion systems: A higher order analysis
Authors: Riaz Syed Shahed , Sharma Rahul , Bhattacharyya S. P. , Ray D. S.
Published: August 2007

We analyze the condition for instability and pattern formation in reaction-diffusion systems beyond the usual linear regime. The approach is based on taking into account perturbations of higher orders. Our analysis reveals that nonlinearity present in the system can be instrumental in determining the stability of a system, even to the extent of destabilizing one in a linearly stable parameter regime. The analysis is also successful to account for the observed effect of additive noise in modifying the instability threshold of a system. The analytical study is corroborated by numerical simulation in a standard reaction-diffusion system.
Nonvolatile resistive switching memory utilizing gold nanocrystals embedded in zirconium oxide
Authors: Guan Weihua , Long Shibing , Jia Rui , Liu Ming
Published: August 2007

Resistive switching characteristics of ZrO2 films containing gold nanocrystals (nc-Au) are investigated for nonvolatile memory applications. The sandwiched top electrode/ZrO2 (with nc-Au embedded)/n+ Si structure exhibits two stable resistance states (high-resistance state and low-resistance state). By applying proper voltage bias, resistive switching from one state to the other state can be achieved. This resistive switching behavior is reproducible and the ratio between the high and low resistances can be as high as two orders. The intentionally introduced nc-Au in ZrO2 films can improve the device yield greatly. ZrO2 films with gold nanocrystals embedded are promising to be used in the nonvolatile resistive switching memory devices.
Hard/soft-acid/base principle and the reaction AhBs+AsBh→AhBh+AsBs
Authors: Goodisman Jerry
Published: August 2007

A demonstration of the hard/soft-acid/base principle involves showing that the energy change for AhBs+AsBh→AhBh+AsBs is always negative. We point out problems with assumptions made about hardness and strength of the components, but emphasize that problems with the way in which energies are calculated are even more important.
Modulation spectroscopic investigation on lattice polarity of gallium nitride
Authors: Katayama Ryuji , Onabe Kentaro , Yaguchi Hiroyuki , Matsushita Tomonori , Kondo Takashi
Published: August 2007

A lattice polarity determination method for GaN is demonstrated, which is based on a capability of modulation spectroscopy for the assignment of electric-field directions performed nondestructively using simple optical setups. A strong spontaneous polarization induces an upward band bending toward +c surfaces and a downward but weaker bending toward −c surfaces for typical films with small residual strains and electron densities. This difference is distinguishable in terms of the spectral-phase flip, utilizing photoreflectance, and electroreflectance. Quantitative analysis revealed the exciton dissociation at a high-field region of +c surfaces consistent with the band profile derived as a solution of Poisson equation.
Small plasma source for materials application
Authors: Vizir A. , Oks E. M. , Salvadori M. C. , Teixeira F. S. , Brown I. G.
Published: August 2007

We describe a small hollow-cathode plasma source suitable for small-scale materials synthesis and modification application. The supporting electrical system is minimal. The gaseous plasma source delivers a plasma ion current of up to about 1mA. Here we outline the source construction and operation, and present some of its basic performance characteristics.
Soft magnetic property and magnetic exchange correlation in high-density Fe-Co alloy cluster assemblies
Authors: Peng D. L. , Yamada H. , Sumiyama K. , Hihara T. , Kumagai K.
Published: August 2007

Magnetically soft Fe-Co alloy cluster-assembled films were produced at room temperature by an energetic cluster deposition. Size-monodispersed Fe-Co alloy clusters whose average sizes ranged between 8 and 14 nm were obtained using a plasma-gas-condensation-type cluster deposition apparatus. Positively charged clusters in a cluster beam were accelerated electrically and deposited onto a negatively biased substrate together with neutral clusters from the same cluster source, leading to formation of high-density Fe-Co alloy cluster-assembled films. Magnetic properties were observed for these films prepared by changing the bias voltage. Based on the temperature dependence of magnetic coercivity, we estimated the effective magnetic anisotropy constant, Keff, and magnetic exchange length Lex (or Dex) as a function of the packing fraction in the Fe-Co cluster-assembled films: Keff decreases and Lex (or Dex) increases dramatically with the packing fraction.
Theory of superfast fronts of impact ionization in semiconductor structures
Authors: Rodin Pavel , Ebert Ute , Minarsky Andrey , Grekhov Igor
Published: August 2007

We present an analytical theory for impact ionization fronts in reversely biased p+-n-n+ structures. The front propagates into a depleted n base with a velocity that exceeds the saturated drift velocity. The front passage generates a dense electron-hole plasma and in this way switches the structure from low to high conductivity. For a planar front we determine the concentration of the generated plasma, the maximum electric field, the front width, and the voltage over the n base as functions of front velocity and doping of the n base. The theory takes into account that drift velocities and impact ionization coefficients differ between electrons and holes, and it makes quantitative predictions for any semiconductor material possible.
Size-modified d bands and associated interband absorption of Ag nanoparticles
Authors: Balamurugan B. , Maruyama Toshiro
Published: August 2007

The present study shows important evidence revealing an intimate relationship between the size-induced modifications of electronic structure and optical properties of Ag nanoparticles. Optical absorption spectra of Ag nanoparticles consisting of two predominant peaks corresponding to characteristic plasmon absorption due to the collective oscillations of conduction-band electrons and an interband absorption due to the transition of electrons from the completely occupied d bands to an empty state above the Fermi level in the conduction band have been observed to depend on the nanoparticle size. On the reduction of nanoparticle size, the interband absorption peak becomes sharp and intense and its peak position shifts towards the lower energy side, which is found to be associated with the size-induced changes in the d bands observed by x-ray photoelectron spectroscopy.
Observation of gate bias dependent interface coupling in thin silicon-on-insulator metal-oxide-semiconductor field-effect transistors
Authors: Jung YoungChai , Cho KeunHwi , Hwang SungWoo , Ahn David , Yu YunSeop
Published: August 2007

We fabricated and characterized a silicon-on-insulator (SOI) metal-oxide-semiconductor field-effect transistor with a SOI film thickness of 26nm. The measured data at room temperature showed that the transconductance peak in the front gate bias shifted and then split into two peaks as the back gate voltage (VBS) decreased. The VBS regime of this splitting was opposite to that of thick SOI devices, suggesting a different physical mechanism in our thin device. Our device also showed VBS dependences of the threshold voltage and the subthreshold swing, which were different from those of thick SOI devices. Our data were explained by the volume inversion of a thin SOI in which both front and back gates strongly modulated the conduction band and charge state of the SOI. The splitting was interpreted as due to the population of the second subband of a triangular quantum well.
Life of thermal bubble on platinum microheater
Authors: Kim Ho-Young , Jeong Kwang-Hun , Ko Seunghyun , Lee Heon Ju , Lee Yoon Pyo , Chang Young Soo
Published: August 2007

When electrical current is supplied to a microline heater immersed in liquid, a microthermal bubble can be formed. The bubble grows until it becomes too large to adhere to a solid surface and finally departs into liquid completing its life. Here we report the experimental results associated with the life of a thermal bubble continuously heated by a platinum microheater. We investigated the effects of the heater dimensions on the nucleation temperature. It was found that a bubble nucleates at lower temperature as the heater gets wider. We also measured the departure diameter and frequency of thermal bubbles depending on the thermal conditions of the microheater and the ambient liquid. As the microheater temperature increases, both the departure diameter and frequency increase, showing different behaviors from those of macroscale boiling. However, as the ambient liquid temperature rises, the departure diameter decreases despite the increase of the departure frequency. Finally, the transient temperature profile of the microheater during bubble formation process was measured. Rapid drop and rise of the temperature were observed, which are attributed to the small-scale convection of cold ambient liquid.
Morphology of threading dislocations in high-resistivity GaN films observed by transmission electron microscopy
Authors: Lu L. , Shen B. , Xu F. J. , Xu J. , Gao B. , Yang Z. J. , Zhang G. Y. , Zhang X. P. , Xu J. , Yu D. P.
Published: August 2007

Morphology of threading dislocations (TDs) in GaN films with different resistivities grown on sapphire by means of metal organic chemical vapor deposition has been investigated using transmission electron microscopy (TEM). GaN films with different resistivities are achieved at various annealing pressures of the nucleation layer (NL). It is observed that the TDs are almost all straight and perpendicular to the sapphire surface in high-resistivity GaN films, while they are significantly bent and interactive in low-resistivity GaN films. The analysis results based on the x-ray diffractometry and TEM demonstrate that the density and morphology of TDs change with annealing pressure of the NL. It is concluded that the annealing pressure of the NL effectively controls the size, density, and coalescence rate of the islands, and thus determines the density and morphology of TDs in GaN.
Analog electronic cochlea with mammalian hearing characteristics
Authors: Martignoli S. , van der Vyver J.-J. , Kern A. , Uwate Y. , Stoop R.
Published: August 2007

Systems close to bifurcations can be used as small-signal amplifiers. Biophysical measurements suggest that the active amplifiers present in the mammalian cochlea are systems close to a Hopf bifurcation. The pure tone and transient signal output of our electronic hearing sensor based on this observation provides output that is fully compatible with the electrophysiological data from the mammalian cochlea. In particular, it reproduces all salient nonlinear effects displayed by the cochlea.
High-performance thin film transistors from semiconducting liquid crystalline phases by solution processes
Authors: Zhang Fapei , Funahashi Masahiro , Tamaoki Nobuyuki
Published: August 2007

The authors have prepared liquid crystalline (LC) semiconducting thin films with smectic phases at room temperature from 5-propyl-5″-(4-pentylphenyl)-2,2′:5′,2″-terthiophene (3-TTPPh-5) by spin-coating process. The films consist of large-size (approximately several tens of micrometers) LC domains with a lamellar structure. The ordering of molecular packing within the smectic layer is enhanced after annealing. The performance of thin film transistors (TFTs) based on 3-TTPPh-5 is influenced largely by silane agent modification of the dielectric. The octyltrichlorosilane (OTS) treatment enhances performance and leads to a high hole mobility of more than 4×10−2cm2∕Vs in ambient air. It is attributed to the formation of highly ordered domains with the size comparable to channel length of the TFT as well as the favorable interaction between OTS and LC molecules.
Intramolecular vibrational energy redistribution from a high frequency mode in the presence of an internal rotor: Classical thick-layer diffusion and quantum localization
Authors: Manikandan Paranjothy , Keshavamurthy Srihari
Published: August 2007

We study the effect of an internal rotor on the classical and quantum intramolecular vibrational energy redistribution (IVR) dynamics of a model system with three degrees of freedom. The system is based on a Hamiltonian proposed by Martens and Reinhardt [J. Chem. Phys. 93, 5621 (1990)] to study IVR in the excited electronic state of para-fluorotoluene. We explicitly construct the state space and show, confirming the mechanism proposed by Martens and Reinhardt, that an excited high frequency mode relaxes via diffusion along a thick layer of chaos created by the low frequency-rotor interactions. However, the corresponding quantum dynamics exhibits no appreciable relaxation of the high frequency mode. We attribute the quantum suppression of the classical thick-layer diffusion to the rotor selection rules and, possibly, dynamical localization effects.
Making graphene visible
Authors: Blake P. , Hill E. W. , Castro Neto A. H. , Novoselov K. S. , Jiang D. , Yang R. , Booth T. J. , Geim A. K.
Published: August 2007

Microfabrication of graphene devices used in many experimental studies currently relies on the fact that graphene crystallites can be visualized using optical microscopy if prepared on top of Si wafers with a certain thickness of SiO2. The authors study graphene’s visibility and show that it depends strongly on both thickness of SiO2 and light wavelength. They have found that by using monochromatic illumination, graphene can be isolated for any SiO2 thickness, albeit 300nm (the current standard) and, especially, ≈100nm are most suitable for its visual detection. By using a Fresnel-law-based model, they quantitatively describe the experimental data.
Asymmetric magnetization reversal behavior in exchange-biased NiFe∕MnPt bilayers in two different anisotropy regimes: Close and far from critical thickness
Authors: Spenato D. , Castel V. , Pogossian S. P. , Dekadjevi D. T. , Ben Youssef J.
Published: August 2007

The effect of the ratio between the uniaxial and unidirectional anisotropy on magnetization reversal in NiFe∕MnPt bilayers has been systematically studied using vectorial vibrating magnetometer. Depending on the balance between these two anisotropies the magnetization reverses either in the opposite or the same semicircles during the ascending and descending branches of the hysteresis loop. A simple modified coherent rotation model provides a good description of the magnetization reversal in these bilayers.
Parity effect in Al and Nb single electron transistors in a tunable environment
Authors: Savin A. M. , Meschke M. , Pekola J. P. , Pashkin Yu. A. , Li T. F. , Im H. , Tsai J. S.
Published: August 2007

Two different types of Cooper pair transistors, with Al and Nb islands, have been investigated in a tunable electromagnetic environment. The device with an Al island demonstrates gate charge modulation with 2e periodicity in a wide range of environmental impedances at bath temperatures below 340mK. Contrary to the results of the Al sample, the authors were not able to detect 2e periodicity under any conditions on similar samples with Nb island. The authors attribute this to the material properties of Nb.
Texture memory and strain-texture mapping in a NiTi shape memory alloy
Authors: Ye B. , Majumdar B. S. , Dutta I.
Published: August 2007

The authors report on the near-reversible strain hysteresis during thermal cycling of a polycrystalline NiTi shape memory alloy at a constant stress that is below the yield strength of the martensite. In situ neutron diffraction experiments are used to demonstrate that the strain hysteresis occurs due to a texture memory effect, where the martensite develops a texture when it is cooled under load from the austenite phase and is thereafter “remembered.” Further, the authors quantitatively relate the texture to the strain by developing a calculated strain-texture map or pole figure for the martensite phase, and indicate its applicability in other martensitic transformations.
Identifying sudden cardiac death risk and specifying its occurrence time by analyzing electrocardiograms in natural time
Authors: Varotsos P. A. , Sarlis N. V. , Skordas E. S. , Lazaridou M. S.
Published: August 2007

Sudden cardiac death (SCD) is a frequent cause of death and may occur even if the electrocardiogram seems to be similar to that of a healthy individual. A method which not only identifies the risk but also provides an estimate of the time of an impending cardiac arrest is proposed. Analyzing 159 electrocardiograms in natural time, the authors find that the key quantity is the entropy change under time reversal. After it becomes maximum at the scale of 13 heartbeats, ventricular fibrillation starts within ∼3h in 16 out of 18 SCDs. The method also distinguishes congestive heart failure patients from SCD.
Incipient plasticity in metallic glass modulated nanolaminates
Authors: Wang Y. M. , Hamza A. V. , Barbee T. W.
Published: August 2007

The plastic deformation in copper-zirconium nanocrystalline-amorphous nanolaminates is investigated by means of stress-relaxation experiments at a range of initial stress levels. Progressive multistep relaxation cycles reveal that the onset of plastic deformation occurs at a much lower stress level in nanocrystalline-amorphous nanolaminate than in crystalline-crystalline nanolaminates or other nanostructured materials. The derived activation volumes and strain rate sensitivities imply interfacial dislocation mechanisms, consistent with the observations from postmorterm transmission electron microscopy. This indicates that the crystalline-amorphous interfaces may be the preferred source for dislocation nucleation and/or emission.
Identification of sub-band-gap absorption features at the HfO2∕Si(100) interface via spectroscopic ellipsometry
Authors: Price J. , Lysaght P. S. , Song S. C. , Li Hong-Jyh , Diebold A. C.
Published: August 2007

Spectroscopic ellipsometry is used to characterize charge trapping defect states in thin HfO2 gate dielectric films deposited by atomic layer deposition on chemically oxidized p-type Si (100) substrates. The intensity of specific absorption features detected below the band gap of HfO2 at 2.9 and 4.75eV is clearly distinguished from the Si critical points; however, repeating this spectroscopic evaluation for identical HfO2 films deposited and annealed on fused silica substrates results in no defect features detected. The HfO2∕Si(100) results, therefore, suggest these oxygen deficient defects are not intrinsic to HfO2 but reside primarily at the interface with the silicon substrate. The feasibility of utilizing spectroscopic ellipsometry to identify stoichiometric variations at the SiO2∕Si(100) interface and the corresponding changes associated with the electrical performance is presented.
Two-dimensional refractive index profiling by using differential near-field scanning optical microscopy
Authors: Tsai Wan-Shao , Wang Way-Seen , Wei Pei-Kuen
Published: August 2007

The authors present two-dimensional reconstruction of the refractive index profile of an optical waveguide by using differential near-field optical microscopy. Using an inverse algorithm, the refractive index distribution is obtained directly from the measured optical near-field and its derivatives without any assumption of the index profile. The proposed method also takes advantage of subwavelength resolution and low noises in the waveguide region. Two-dimensional index profile reconstruction of a single mode fiber is measured for the demonstration. The measured optical field distribution and refractive index profile agree quite well with the calculated mode and the known index profile.
Spin-dependent transport in nanocomposites of Alq3 molecules and cobalt nanoparticles
Authors: Tanabe Shinichi , Miwa Shinji , Mizuguchi Masaki , Shinjo Teruya , Suzuki Yoshishige , Shiraishi Masashi
Published: August 2007

The authors have observed magnetoresistance (MR) ratios of 12% and 0.1% at 4.2 and 290K, respectively, in a nanocomposite in which Co nanoparticles are embedded in the fine molecular structure of a tris(8-hydroxyquinoline) aluminum (Alq3) matrix. Structural analyses, magnetization measurements, and conduction properties of the device reveal that the MR effect is induced by spin-dependent transport in the Alq3.
Dynamic conductance of a nanowire cross junction
Authors: Wang L. G. , Chan K. S.
Published: August 2007

The dynamic conductance of a nanowire cross junction is investigated with the scattering matrix approach including the effect of the displacement current. The intrawire conductance is basically inductive, but it is capacitative near to a quasibound state. The interwire conductance is basically capacitative, except near a quasibound state where it is inductive. In 9–18nm wires, interwire transmission of terahertz signals is suppressed for Fermi energy near to the first subband edge and the quasibound state below the second subband, thus limiting the junction’s operating speed. For these Fermi energies, the maximum operation frequency decreases with the increase in the wire diameter.
Dielectric properties of PbNb2O6 ferroelectric ceramics at cryogenic temperatures
Authors: De los S. Guerra J. , Venet M. , Garcia D. , Eiras J. A. , Guerrero F.
Published: August 2007

Complex dielectric permittivity measurements in PbNb2O6 ceramics were performed in a frequency and temperature range of 1kHz–1MHz and from 15to900K, respectively. The results revealed two dielectric anomalies showing typical characteristics of relaxor ferroelectric materials at cryogenic temperatures. Comparison with other tetragonal tungsten bronze (TTB) structure-type materials suggests the existence of successive phase transitions, which until now were not reported. The observed low temperature dielectric behaviors seem to be due to intrinsic physical characteristics related to the TTB structure.
Race, Gender, and Statistical Representation: Predatory Mortgage Lending and the US Community Reinvestment Movement
Authors: Wyly Elvin K , Atia Mona , Lee Elizabeth , Mendez Pablo
Published: August 2007

American mortgage markets, once arenas of discrimination by exclusion, now operate as venues of segmentation and discrimination by inclusion: credit is widely available, but its terms vary enormously. One market segment involves sophisticated predatory practices in which certain groups of borrowers are targeted for high-cost credit that strips out home equity and worsens the risks of delinquency, default, and foreclosure. Unfortunately, it has become more difficult to measure inequalities of predatory lending: race–ethnicity and gender are ‘disappearing’ from the main public data source used to study, organize, and mobilize on issues of lending inequalities. In this paper, we present a mixed-methods case study of statistical representation of homeowners and homebuyers marginalized by race, ethnicity, and gender. A theoretical examination of official data-collection practices is followed by a discussion of alternative meanings of racial–ethnic and gender nondisclosure. Interviews with a sample of homeowners and homebuyers in the Washington, DC, area reveal some respondent ambivalence about the details of data-collection practices, but provide no consistent support for the idea that nonreporting is solely a matter of individual choice. Econometric analyses indicate that nondisclosure is driven primarily by lending-industry practices, with the strongest disparate impacts in African-American suburbs. Predatory lending is producing ambivalent spaces of racial-ethnic and gender invisibility, requiring new strategies in the reinvestment movement.
Emerging Districts Facing Structural Reform: The Madrid Electronics District and the Reshaping of the Spanish Telecom Monopoly
Authors: Rama Ruth , Ferguson Deron
Published: August 2007

In this paper we identify some sources of resilience in regional production districts (RPDs) faced with external shocks. We analyze Madrid's electronics district, which has managed to survive and prosper even after the turbulent period of the early 1990s when Spanish telecommunications services and product markets were liberalized. The study of structural changes alone in RPDs as they respond to external shocks may not sufficiently account for other important sources of some districts' resilience. Also playing important roles may be the conscious strategies of districts' leading firms. We study changes occurring after shock with quantitative data coming from surveys performed before and after telecommunications reform was implemented. Most other recent studies of change in RPDs compare instead the current situation with a qualitative description of the previous situation. We also build on previous empirical work, provide recent regional statistics, and compile information from the daily business press published over more than a decade. Anticipating the end of its various monopolies well in advance, the Spanish carrier Telefónica began searching for new growth opportunities as early as the mid-1980s. With Madrid's electronics district having evolved from a state-anchored district to an emerging high-technology district, Telefónica benefited from its production and development linkages there which confered a competitive advantage in winning foreign markets, especially in Latin America. Since the crisis, a process of reagglomeration has occurred in the district. Several large multinational suppliers of telecom equipment have relocated some of their production to Madrid and assigned greater importance to their R&D laboratories there.
Technology and the Architecture of Markets: Reconfiguring the Canadian Equity Market
Authors: Majury Niall
Published: August 2007

This paper examines the relation between technical possibilities, liberal logics, and the concrete reconfiguration of markets. It focuses on the enrolling of innovations in communication and information technologies into the markets traditionally dominated by stock exchanges. With the development of capacities to trade on-screen, the power of incumbent market makers has been challenged as a less stable array of competing quasi-public and private marketplaces emerges. Developing a case study of the Toronto Stock Exchange, I argue that narrative emphasis on the performative power of sociotechnical innovations, the deterritorialisation of financial relations, and the erosion of state capacities needs qualification. A case is made for the importance of developing an understanding of: the spaces of encounter between emerging social technologies and property rights, rules of exchange, and structures of governance; and the interplay of orderings of different institutional composition and spatial reach in the reconfiguration of market architectures. Only then can a better grasp be gained of the evolving dynamics between making markets, the regulatory powers of the state, and their delimitations.
Transit-Oriented Development's Ridership Bonus: A Product of Self-Selection and Public Policies
Authors: Cervero Robert
Published: August 2007

Transit-oriented development is shown to produce an appreciable ridership bonus in California. This is partly due to residential self-selection—that is, a lifestyle preference for transit-oriented living—as well as factors like employer-based policies that reduce free parking and automobile subsidies. Half-mile catchments of station areas appear to be indifference zones in the sense that residents generally ride transit regardless of local urban design attributes. Out-of-neighborhood attributes, like job accessibility and street connectivity at the destination, on the other hand, have a significant bearing on transit usage among station-area residents. The presence of self-selection, shown using nested logit modeling, underscores the importance of removing barriers to residential mobility so that households are able to sort themselves, via the marketplace, to locations well served by transit. Market-responsive zoning, flexible residential parking policies, location efficient mortgages, and adaptive reuse of parking lots are also promising tools for expanding the supply of transit-based housing.
Infrastructure Pricing and Competition between Modes in Urban Transport
Authors: Pels Eric , Verhoef Erik T
Published: August 2007

Privatization of transit and roads is gaining increasing interest. This paper develops a model in which infrastructure pricing and optimal capacity are analyzed under both public and private regimes. It compares optimal outputs (number of passengers) and capacities of public and private operators of rail transport. A crucial aspect of the paper is competition between modes: for instance, how are optimal outputs and capacities of the private railway operator influenced by the strategic decisions on the road capacity and tolls for the private (car) alternative?
Accessibility Indicators for Location Choices of Offices: An Application to the Intraregional Distributive Effects of High-Speed Rail in the Netherlands
Authors: Willigers Jasper , Floor Han , van Wee Bert
Published: August 2007

Accessibility is often seen to be an important determinant of the location of economic activities. This paper focuses on the specification of accessibility indicators for modelling the location choices of offices, with particular application to the upcoming implementation of a high-speed railway line in the Netherlands. Potential accessibility indicators are formulated, whereby attention is given to the shape of the impedance function and to the role of competitive transport modes in a transport mode's accessibility effect. These indicators are then tested in a discrete choice model on the location of office employment. Finally the accessibility indicators are used to explore the effects of the upcoming domestic high-speed train services in the Netherlands. The analyses show that a Box–Cox impedance function performs best for this application and significantly better than the exponential and power functions. The derived potential accessibility indicators have much explanatory capability for location attractiveness at a regional level, but at an intraregional level connectivity measures become more influential. Finally, it has been found that the accessibility effect of the future high-speed train connection is larger for business travel than for commuting, the value of time of travellers being a dominant factor.
The WTP for Facilities at the Amsterdam Zuidas
Authors: de Graaff Thomas , de Groot Henri L F , Rodenburg Caroline A , Verhoef Erik T
Published: August 2007

This paper reports the results of a stated preference study investigating the willingness-to-pay (WTP) of employees at the Amsterdam Zuidas for the presence of nonshopping and shopping facilities. The Amsterdam Zuidas area, surrounding the current train–metro–tram station Amsterdam Zuid World-Trade-Centre, is the largest multifunctional land-use project currently under development in the Netherlands. For nonshopping facilities, the results show that employees have the highest WTP for the presence of day-care centres and public transport facilities, and the lowest for public and recreation facilities. The average WTP for the presence of nonshopping facilities amounts to approximately €29 per month per employee. The WTP for the presence of shopping facilities is estimated at €25 per month per employee on average, and is in absolute value highest for supermarkets and lowest for flowershops and dry cleaners.