bluuebunny/crossref_metadata_2025 huggingface dataset:
Ferroelectric properties of (117)- and (001)-oriented Bi3.25La0.75Ti3O12 polycrystalline thin films
Authors: Sun Yu-Ming , Chen Yi-Chan , Gan Jon-Yiew , Hwang Jenn-Chang
Published: October 2002

Highly (117)- and (001)-oriented Bi3.25La0.75Ti3O12 (BLT) thin films were fabricated on Pt/TiO2/SiO2/Si(100) substrates by chemical solution deposition under the appropriate baking and crystallization conditions. The (117)-oriented BLT films exhibited higher remanent polarization (2Pr=24 μC/cm2), than did (001)-oriented BLT films, which exhibited only a slight amount of polarization (2Pr=6.6 μC/cm2). The results of fatigue and retention tests revealed that neither film was fatigued up to 1×1010 switching cycles, and the retained charge was unchanged for 1×104 s.
Differential x-ray phase contrast imaging using a shearing interferometer
Authors: David C. , Nöhammer B. , Solak H. H. , Ziegler E.
Published: October 2002

An x-ray interferometer has been developed that uses two transmission phase gratings to analyze wave front distortions in the hard x-ray range. The interferometer is insensitive to mechanical drift and vibrations, and it is tunable over a wide range of photon energies. This setup was used for differential phase contrast imaging of low-absorbing test objects. We obtained micrographs with moiré fringes of good visibility, which revealed the local phase shift gradient caused by the objects. A comparison with numerically simulated images indicates that quantitative analysis of unknown phase objects is possible.
Contribution of Reynolds stress distribution to the skin friction in wall-bounded flows
Authors: Fukagata Koji , Iwamoto Kaoru , Kasagi Nobuhide
Published: October 2002

A simple expression is derived of the componential contributions that different dynamical effects make to the frictional drag in turbulent channel, pipe and plane boundary layer flows. The local skin friction can be decomposed into four parts, i.e., laminar, turbulent, inhomogeneous and transient components, the second of which is a weighted integral of the Reynolds stress distribution. It is reconfirmed that the near-wall Reynolds stress is primarily important for the prediction and control of wall turbulence. As an example, the derived expression is used for an analysis of the drag modification by the opposition control and by the uniform wall blowing/suction.
Focused-electron-beam-induced deposition of freestanding three-dimensional nanostructures of pure coalesced copper crystals
Authors: Utke I. , Luisier A. , Hoffmann P. , Laub D. , Buffat P. A.
Published: October 2002

We report on direct writing of three-dimensional freestanding nanostructures of Cu by use of a focused electron beam (FEB) and the metalorganic precursor hfac-Cu-TMVS. Freestanding horizontal rods were deposited over about 10 μm length and consist of small 2–5 nm Cu nanocrystals dispersed in an amorphous matrix containing carbon, fluorine, silicon, and oxygen. The freestanding horizontal rods were used as support for further vertical deposits resulting in tips of coalesced facetted Cu nanocrystals of up to 100 nm in size. The almost constant deposition rate of 5–6 nm/s is in contrast to vertical tips on bulk supports, which show a deposition rate decreasing from 23 to 10 nm/s. The above results suggest a thermal decomposition process induced by electron energy absorption.
Super-resolution digital holographic imaging method
Authors: Liu Cheng , Liu Zhigang , Bo Feng , Wang Yong , Zhu Jianqiang
Published: October 2002

A method to realize super-resolution digital holographic imaging is demonstrated experimentally. By placing a grating in front of the specimen, more object waves can reach the charge-coupled devices target during the recording of a digital hologram, and the image reconstructed from the digital hologram has a resolution over the diffraction limit of the ordinary holographic system. This method overcomes the crucial drawback of digital holography, and may find many applications in three-dimensional digital imaging and microscopy.
Resin flow in fiber preforms
Authors: Abrate Serge
Published: October 2002

In a number of manufacturing processes for composite structures, resin flows through fiber reinforcement that is prearranged in a mold or a die. This article presents a review of mathematical models used to study the flow of resin through fiber reinforcement. The general approach is to consider the resin as a fluid propagating through a porous medium: the mold (or die) cavity partially filled with fiber reinforcement and other filler material. The resistance of the reinforcement to fluid flow is characterized by the permeability tensor and many analytical, numerical, and experimental techniques have been developed to predict or to measure the components of that tensor. The behavior of the resin depends on its viscosity, which depends on temperature and the degree of cure. Often mold filling is completed before any appreciable temperature change or curing occurs, so the analysis of this phase of the process is uncoupled from the thermal and curing problems. In other cases all three problems are coupled and should be solved simultaneously. Several complicating factors must be considered: 1) the deformation of the reinforcement during the preforming stage, during mold closure, or during resin injection, can affect permeabilities and flow patterns; 2) gaps between the reinforcement and the surface of the mold can cause edge flows that bypass the expected flow pattern; and 3) the inhomogeneous nature of the reinforcement with higher flow resistance inside fiber bundles than in surrounding gaps leads to complex flow patterns near the flow front and to the formation of microvoids. This article reviews the mathematical models that are required in order to simulate composite manufacturing processes in which resin flows through fiber reinforcement. The numerical implementation of these models using the finite element method or other numerical techniques is beyond the scope of this review. The bulk of the current body of knowledge in this area was developed since 1990. There are 165 references in this review article.
Efficiency of nonideal Carnot engines with friction and heat losses
Authors: Rebhan E.
Published: October 2002

In nonideal thermodynamic engines the efficiency is well below the Carnot efficiency η=1−T1/T2. In 1975 an expression for the efficiency of a nonideal Carnot engine with heat losses was derived, yielding η=1−T1/T2 at maximum power output. In this paper, a corresponding relation is obtained for more general nonideal Carnot engines. If there are friction losses only, the result is η=(1−T1/T2)/2. If friction and heat losses are both included, the efficiency at maximum power depends on a dimensionless parameter λ* that takes into account the effects of friction and heat conduction, and can vary between the values obtained for friction and heat losses separately, (1−T1/T2)/2<ηpmax<1−T1/T2. A general relation between efficiency and power output is established, and it is shown that an appreciable gain in efficiency can be obtained at a power output only slightly below its maximum.
Demonstration of negative group delays in a simple electronic circuit
Authors: Nakanishi T. , Sugiyama K. , Kitano M.
Published: October 2002

We present a simple electronic circuit that produces negative delays. When a pulse is sent to the circuit as input, the output is a pulse with a similar wave form that is shifted forward in time. The advance time or negative delay can be increased to the order of seconds so that we can observe the advance with the naked eye by observing two light emitting diodes that are connected to the input and the output. The negative group delay in the electronic circuit shares the same mechanism with superluminal light propagation, where the group velocity exceeds the speed of light or even becomes negative.
When physical intuition fails
Authors: Singh Chandralekha
Published: October 2002

We analyze the problem-solving strategies of physics professors in a case where their physical intuition fails. A nonintuitive introductory-level problem was identified and posed to twenty physics professors. The problem placed the professors in a situation often encountered by students, and their response highlights the importance of intuition and experience in problem solving. Although professors had difficulty in solving the problem under the time constraint, they initially employed a systematic approach, for example, visualizing the problem, considering various conservation laws, and examining limiting cases. After finding that familiar techniques were not fruitful, they made incorrect predictions based on one of two equally important factors. In contrast, other more familiar problems that require the consideration of two important principles (for example, conservation of both energy and momentum for a ballistic pendulum) were quickly solved by the same professors. The responses of students who were given the same problem reflected no overarching strategies or systematic approaches, and a much wider variety of incorrect responses were given. This investigation highlights the importance of teaching effective problem-solving heuristics, and suggests that instructors assess the difficulty of a problem from the perspective of beginning students.
Antibodies to high‐density lipoprotein and β2‐glycoprotein I are inversely correlated with paraoxonase activity in systemic lupus erythematosus and primary antiphospholipid syndrome
Authors: Delgado Alves J. , Ames P. R. J. , Donohue S. , Stanyer L. , Noorouz‐Zadeh J. , Ravirajan C. , Isenberg D. A.
Published: October 2002

Objective

To determine the prevalence of anti–high‐density lipoprotein (anti‐HDL) antibodies and to establish a possible relationship between anti‐HDL, anticardiolipin antibodies (aCL), anti–β2‐glycoprotein I (anti‐β2GPI), and paraoxonase (PON) activity in patients with systemic lupus erythematosus (SLE) and primary antiphospholipid syndrome (APS).

Methods

Thirty‐two patients with SLE and 36 with primary APS were enrolled in a cross‐sectional study. Twenty age‐ and sex‐matched healthy subjects were used as controls. Serum levels of IgG and IgM aCL, anti‐β2GPI, and antiprothrombin antibodies and IgG anti‐HDL were measured by enzyme‐linked immunosorbent assay. Total cholesterol, HDL cholesterol, HDL2, and HDL3 were determined by standard enzymatic techniques. PON activity was assessed by quantification of nitrophenol formation, and total antioxidant capacity (TAC) by chemiluminescence.

Results

Levels of total HDL, HDL2, and HDL3 were reduced in patients with SLE compared with controls (mean ± SD 0.51 ± 0.3, 0.37 ± 0.3, and 0.14 ± 0.1 mmoles/liter, respectively, versus 1.42 ± 0.9, 1.01 ± 0.7, and 0.40 ± 0.2). Patients with SLE and primary APS had higher titers of anti‐HDL antibodies and lower PON activity than controls. In the SLE population, PON activity was inversely correlated with IgG anti‐HDL titers (r = −0.48, P = 0.005) whereas in the primary APS population, IgG anti‐β2GPI was the only independent predictor of PON activity (r = −0.483, P = 0.003). In the SLE group, anti‐HDL was inversely correlated with TAC (r = −0.40, P < 0.02), and PON activity was positively correlated with TAC (r = 0.43, P < 0.02).

Conclusion

IgG anti‐HDL and IgG anti‐β2GPI antibodies are associated with reduced PON activity in patients with SLE and primary APS. Since the physiologic role of PON is to prevent low‐density lipoprotein oxidation with its attendant atherogenic effects, the reported interactions may be relevant to the development of atherosclerosis in SLE and primary APS.
Interactions of antimitotic peptides and depsipeptides with tubulin
Authors: Hamel Ernest
Published: October 2002

Tubulin is the target for an ever increasing number of structurally unusual peptides and depsipeptides isolated from a wide range of organisms. Since tubulin is the subunit protein of microtubules, the compounds are usually potently toxic to mammalian cells. Without exception, these (depsi)peptides disrupt cellular microtubules and prevent spindle formation. This causes cells to accumulate at the G2/M phase of the cell cycle through inhibition of mitosis. In biochemical assays, the compounds inhibit microtubule assembly from tubulin and suppress microtubule dynamics at low concentrations. Most of the (depsi)peptides inhibit the binding of Catharanthus alkaloids to tubulin in a noncompetitive manner, GTP hydrolysis by tubulin, and nucleotide turnover at the exchangeable GTP site on β‐tubulin. In general, the (depsi)peptides induce the formation of tubulin oligomers of aberrant morphology. In all cases tubulin rings appear to be formed, but these rings differ in diameter, depending on the (depsi)peptide present during their formation. Published 2002 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 66: 142–160, 2002
Three‐dimensional fibroblast–tumor cell interaction causes downregulation of RACK1 mRNA expression in breast cancer cells in vitro
Authors: Seidl Paula , Huettinger Robert , Knuechel Ruth , Kunz‐Schughart Leoni A.
Published: October 2002

Fibroblasts are the most abundant stromal cell type in desmoplastic ductal invasive breast tumors, are a substrate of tumor cell invasion and modify tumor cell behavior. However, the complex interaction between tumor cells and fibroblasts remains incompletely understood. Our aim was to identify candidate genes in tumor cells that are affected by fibroblasts and to reveal new molecules involved in this heterologous interaction. To reflect the in vivo situation, a 3‐D multicellular spheroid coculture model of breast tumor cells and fibroblasts was combined with cell separation technology (MACS and FACS) and molecular analyses, including RAP‐PCR, semiquantitative RT‐PCR and reverse Northern blotting. Three tumor cell lines (BT474, T47D and MCF‐7) with different invasive potential were applied in coculture with normal skin and/or breast tumor‐derived fibroblasts. With the techniques mentioned, 18 different bands in the tumor cDNA band pattern of mono‐ as opposed to cocultures were identified. One of the mRNAs is considered worth further analysis: rack1. Rack1 mRNA was reproducibly suppressed in tumor cells following interaction with fibroblasts. Downregulation was recorded in all tumor cell lines and for cocultures with both types of fibroblast. This indicates a general regulatory mechanism between epithelial tumor cells and fibroblasts, which may be an interesting tumor cell differentiation–independent target for therapy. © 2002 Wiley‐Liss, Inc.
Deletion of chromosomal region 6q14‐16 in prostate cancer
Authors: Verhagen Paul C.M.S. , Hermans Karin G.L. , Brok Mariel O. , van Weerden Wytzke M. , Tilanus Marcel G.J. , de Weger Roel A. , Boon Tom A. , Trapman Jan
Published: October 2002

A detailed analysis of chromosome 6 in DNAs from prostate cancers was performed, to define a region for subsequent search for cancer genes. DNA from 4 prostate cancer cell lines and 11 xenografts was used for CGH and whole‐chromosome allelotyping with polymorphic microsatellite markers. Loss of proximal 6q was studied in more detail by high‐density allelotyping of xenografts, cell lines and 19 prostate tumour specimens from TURP. Seven of 15 xenografts and cell lines showed deletion of proximal 6q by CGH. Gain of 6q was found in 2 samples. Six samples showed 6p gain, and 1 had 6p loss. Allelotyping results were consistent with CGH data in 11 of 15 DNAs. In LNCaP and DU145 cells, CGH showed 6p loss and 6q loss, respectively, but 2 allelic bands were detected for many polymorphic markers on these chromosome arms. These apparent discrepancies might be explained by aneuploidy. In cell line TSU, allelotyping demonstrated chromosome 6 deletion, which was not clearly detected by CGH, indicating loss of 1 copy of chromosome 6 followed by gain of the retained copy during progressive tumour growth. Loss of heterozygosity was detected in 9 of 19 TURP specimens. Combining all data, we found a common minimal region of loss at 6q14‐16 with a length of 8.6 Mbp flanked by markers D6S1609 and D6S417. One hundred and twenty‐three STSs, ESTs, genes and candidate genes mapping in this interval were used to screen xenografts and cell lines for HDs, but none was detected. In summary, chromosome region 6q14‐16 was deleted in approximately 50% of the prostate cancer specimens analysed. The high percentage of loss underscores the importance of genes within this region in prostate cancer growth. © 2002 Wiley‐Liss, Inc.
Effect of the vascular endothelial growth factor receptor‐2 antibody DC101 plus gemcitabine on growth, metastasis and angiogenesis of human pancreatic cancer growing orthotopically in nude mice
Authors: Bruns Christiane J. , Shrader Marissa , Harbison Matthew T. , Portera Charles , Solorzano Carmen C. , Jauch K.‐W. , Hicklin Daniel J. , Radinsky Robert , Ellis Lee M.
Published: October 2002

Vascular endothelial growth factor (VEGF) is the major pro‐angiogenic factor for most tumors. VEGF expression has been shown to be associated with a poor prognosis in human pancreatic cancer. The purpose of our study was to determine the effect of blockade of VEGF receptor‐2 activity with or without gemcitabine on tumor growth and metastasis in an orthotopic model of human pancreatic cancer in nude mice. Therapy with gemcitabine or DC101, a VEGF receptor‐2 antibody, resulted in a significant reduction of primary pancreatic tumor growth compared to untreated controls. The combination of DC101 and gemcitabine inhibited primary pancreatic tumor growth and lymphatic metastasis to a greater degree than either agent alone. Treatment with DC101 decreased vessel counts and increased the area of hypoxic tumor tissue compared to controls. Immunofluorescent double staining for apoptotic endothelial cells demonstrated a significant increase in the number apoptotic endothelial cells 24 days after initiation of therapy with DC101 plus gemcitabine. DC101 plus gemcitabine also increased tumor cell death and decreased tumor cell proliferation in pancreatic tumors. These findings indicate that blockade of VEGF receptor activation interferes with the survival of tumor endothelial cells, resulting in a reduction of primary pancreatic tumor growth in nude mice. Furthermore, the data demonstrate that anti‐VEGF receptor‐2 therapy potentiates the tumoricidal effect of gemcitabine in this model. Anti‐VEGF receptor‐2 therapy in combination with gemcitabine may be a novel therapeutic approach for advanced pancreatic cancer. © 2002 Wiley‐Liss, Inc.
Overexpression of integrin αv promotes human osteosarcoma cell populated collagen lattice contraction and cell migration
Authors: Levinson Howard , Hopper James E. , Ehrlich H. Paul
Published: October 2002

Cells attach and interact with the extracellular matrix (ECM) through heterodimeric αβ integrin receptors. Specifically, the promiscuous αvβ3 integrin and the α2β1 integrin receptors engage numerous matrix components to influence cell adhesion, cell motility, and matrix organization. However, the role of αv integrin mediating cell–collagen interactions is not clear. In the in vitro cell populated collagen lattice (PCL), a model of cell–matrix interaction, integrin receptors play a role in lattice contraction. To elucidate αv integrins' effects on cell–collagen interactions, human osteosarcoma (HOS) cells were transfected with αv integrin (αv‐pcDNA 3.1+). Control HOS cells were transfected with pcDNA 3.1+ vector alone. HOS‐αv cell PCLs contracted to a greater degree than control HOS cell PCLs (P ≤ 0.0001). RT‐PCR revealed that HOS‐αv cells express both β1 and β3 integrins, indicating that αv has the potential to form a partnership with either β1 or β3 integrin. The αvβ3 specific inhibitory antibody LM609 significantly retarded HOS‐αv cell PCL contraction (P ≤ 0.001), suggesting that αvβ3 promotes enhanced HOS‐αv cell PCL contraction. When plated on plastic, control HOS cells show greater elongation compared to HOS‐αv cells. In addition, HOS‐αv cells migrated faster and to a greater degree than control HOS cells (P ≤ 0.0001). The possibility that enhanced HOS‐αv cell migration and HOS‐αv cell PCL contraction was caused by increased myosin ATPase activity was examined. HOS‐αv cells showed less myosin ATPase activity than control HOS cells, by an ATP cell contraction bioassay. The enhancement of HOS‐αv cell migration and lattice contraction appears unrelated to increased myosin ATPase activity. © 2002 Wiley‐Liss, Inc.
Mechanisms regulating the expression, self‐maintenance, and signaling‐function of the bradykinin B2 and B1 receptors
Authors: Prado Gregory N. , Taylor Linda , Zhou Xiaofeng , Ricupero Dennis , Mierke Dale F. , Polgar Peter
Published: October 2002

Bradykinin (BK) is a potent short‐lived effector belonging to a class of peptides known as kinins. It participates in inflammatory and vascular regulation and processes including angioedema, tissue permeability, vascular dilation, and smooth muscle contraction. BK exerts its biological effects through the activation of the bradykinin B2 receptor (BKB2R) which is G‐protein‐coupled and is generally constitutively expressed. Upon binding, the receptor is activated and transduces signal cascades which have become paradigms for the actions of the Gαi and Gαq G‐protein subunits. Following activation the receptor is then desensitized, endocytosed, and resensitized. The bradykinin B1 (BKB1R) is a closely related receptor. It is activated by desArg10‐kallidin or desArg9‐BK, metabolites of kallidin and BK, respectively. This receptor is induced following tissue injury or after treatment with bacterial endotoxins such as lipopolysacharide or cytokines such as interleukin‐1 or tumor necrosis factor‐α. In this review we will summarize the BKB2R and BKB1R mediated signal transduction pathways. We will then emphasize the relevance of key residues and domains of the intracellular regions of the BKB2R as they relate to modulating its function (signal transduction) and self‐maintenance (desensitization, endocytosis, and resensitization). We will examine the features of the BKB1R gene promoter and its mRNA as these operate in the expression and self‐maintenance of this inducible receptor. This communication will not cover areas discussed in earlier reviews pertaining to the actions of peptide analogs. For these we refer you to earlier reviews (Regoli and Barabé, 1980, Pharmacol Rev 32:1–46; Regoli et al., 1990, J Cardiovasc Pharmacol 15(Suppl 6):S30–S38; Regoli et al., 1993, Can J Physiol Pharmacol 71:556–557; Marceau, 1995, Immunopharmacology 30:1–26; Regoli et al., 1998, Eur J Pharmacol 348:1–10). J. Cell. Physiol. 193: 275–286, 2002. © 2002 Wiley‐Liss, Inc.
Innervation of the carotid body: Immunohistochemical, denervation, and retrograde tracing studies
Authors: Ichikawa Hiroyuki
Published: October 2002

This review presents information about multiple neurochemical substances in the carotid body. Nerve fibers around blood vessels and glomus cells within the chemoreceptive organ contain immunoreactivities (IR) for tyrosine hydroxylase (TH), calcitonin gene‐related peptide (CGRP), substance P (SP), galanin (GAL), vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY), calretinin (CR), calbindin D‐28k (CB), parvalbumin (PV), and nitric oxide synthase (NOS). Parasympathetic neurons scattered around the carotid body contain VIP, choline acetyltransferase, and vanilloid receptor 1‐like receptor. In the mammalian carotid body, transection of the carotid sinus nerve (CSN) causes the absence or decrease of CGRP‐, SP‐, and NOS‐immunoreactive (IR) nerve fibers, whereas all NPY‐IR nerve fibers disappear after removal of the superior cervical ganglion. Most VIP‐IR nerve fibers disappear but a few persist after sympathetic ganglionectomy. In addition, the CSN transection appears to cause the acquisition of GAL‐IR in originally immunonegative glomus cells and nerve fibers within the rat carotid body. On the other hand, 4%, 25%, 17%, and less than 1% of petrosal neurons retrogradely labeled from the rat CSN contain TH‐, CGRP‐, SP‐, and VIP‐IR, respectively. In the chicken carotid body, many CGRP‐ and SP‐IR nerve fibers disappear after vagus nerve transection or nodose ganglionectomy. GAL‐, NPY‐, and VIP‐IR nerve fibers mostly disappear after removal of the 14th cervical ganglion of the sympathetic trunk. The origin and functional significance of the various neurochemical substances present in the carotid body is discussed. Microsc. Res. Tech. 59:188–195, 2002. © 2002 Wiley‐Liss, Inc.
Dynamics of water molecules in an alkaline environment
Authors: Nienhuys Han-Kwang , Lock Arjan J. , van Santen Rutger A. , Bakker Huib J.
Published: October 2002

We report on a two-color mid-infrared pump–probe spectroscopic study of the dynamics of the OH stretch vibrations of HDO molecules dissolved in a concentrated (10 M) solution of NaOD in D2O. We observe that spectral holes can be created in the broad OH stretch absorption band that change neither position nor width on a picosecond time scale. This behavior differs strongly from that of pure HDO:D2O where rapid spectral diffusion (τc≈600 fs) occurs. The long-living inhomogeneity indicates that a concentrated aqueous NaOX (X=H,D) solution has a very static hydrogen-bond network. The results also show that the absorption band of the OH stretch vibration consists of two separate classes of OH groups with very different vibrational lifetimes. For component I, the lifetime of the OH stretch vibration is ∼600 fs and increases with OH frequency, which can be explained from the accompanying decrease in the strength of the hydrogen-bond interaction. This component represents HDO molecules of which the OH group is bonded to a D2O molecule via a DO–H⋯OD2 hydrogen bond. For component II, the lifetime is ∼160 fs, and does not show a significant frequency dependence. This component represents HDO molecules that are hydrogen bonded to a D2O molecule or an OD− ion. The short, frequency-independent vibrational lifetime of component II can be explained from the participation of the HDO molecule and its hydrogen-bonded partner in deuteron and/or proton-transfer processes.
Microstructural study of mechanical properties of the ABA triblock copolymer using self-consistent field and molecular dynamics
Authors: Aoyagi Takeshi , Honda Takashi , Doi Masao
Published: October 2002

The molecular mechanism of the strain–stress behavior of the ABA triblock copolymer is studied by combining self-consistent field (SCF) calculation and molecular dynamics (MD) simulation. First, the equilibrium structure was obtained by the SCF calculation. The bridge fraction φbridge was found to be about 0.4, 0.6, and 0.8 for lamellar, cylindrical, and spherical phases, respectively. From the segment distribution calculated by the SCF, the equilibrium chain configuration was generated by the method reported previously [Aoyagi et al., Comput. Phys. Comm. 145, 267 (2002)]. The loading and unloading behavior was then studied by the MD simulation. The loading curve shows a strain-softening, and then a yielding at a strain of about 350%, where the breakup of microdomains takes place. The strain–stress curve in the second elongation-compression cycle is different from that of the first cycle. Such hysteresis effect is seen also for small elongation where the domain breakup does not take place.
Time-resolved resonance Raman spectroscopy and density functional theory investigation of the CH2I–I isomer and CH2I2⋯I molecular complex products produced from ultraviolet photolysis of CH2I2 in the solution phase: Comparison of the structure and chemical reactivity of polyhalomethane isomers and polyhalomethane–halogen atom molecular complexes
Authors: Li Yun-Liang , Wang Dongqi , Phillips David Lee
Published: October 2002

Time-resolved resonance Raman spectra are reported for different concentrations of CH2I2 in cyclohexane solution. The CH2I–I species is observed at low concentrations and it decays on the order of tens of nanoseconds to almost no signal at 100 ns and no other signal is observed up to 15 microseconds. Two species are observed at high concentrations. The first species CH2I–I spectra and lifetime are about the same as that found at low concentration of CH2I2 parent molecule and the second species is a CH2I2⋯I molecular complex observed on the nanosecond to microsecond time scale and formed from bimolecular reaction of iodine atoms with CH2I2 molecules. The chemical reactivity of the CH2I–I species and the CH2I2⋯I molecular complex towards carbon double bonds were investigated using density functional theory calculations. The structure and properties of the CH2I–I species and the CH2I2⋯I molecular complex and their reaction towards ethylene were compared. The CH2I–I species and the CH2I2⋯I both have weak I–I bonds that are the chromophores responsible for similar intense transient absorption bands. However, the geometry of the I–I bond relative to the C–I bond is noticeably different for these two species and this leads to distinctly different chemical reactivity toward carbon double bonds. The CH2I–I isomer readily reacts with ethylene to produce a cyclopropane product and I2 leaving group via a single step and low barrier to reaction while the CH2I2⋯I molecular complex reacts with ethylene to form an ethylene/I intermediate and a CH2I2 leaving group. Probable ramifications for other related molecule–halogen atom complexes are briefly discussed.
Simulations and experiments on magneto-optical diffraction by an array of epitaxial Fe(001) microsquares
Authors: Garcı́a-Mochales P. , Costa-Krämer J. L. , Armelles G. , Briones F. , Jaque D. , Martı́n J. I. , Vicent J. L.
Published: October 2002

Magneto-optic (MO) experimental and computational studies are reported on arrays of epitaxial Fe(001) microsquares. Measuring the transverse Kerr signal, in both reflected and diffracted spots, when the array is exposed to a rotating magnetic field allows the quantification of the magnetization inhomogeneties within the microsquares. The MO signal at diffracted spots is extremely sensitive to magnetization inhomogeneities, while working at a large constant field amplitude eliminates uncertainties due to domain-wall movements. The presence of anomalous peaks at the diffracted MO response is unambiguously assigned to the matching of inhomogeneities of the magnetization distribution to the corresponding pattern periodicity. Interaction between microsquares appears as a second-order effect.
Simultaneous quantification of strain and defects in high-power diode laser devices
Authors: Tomm J. W. , Gerhardt A. , Elsaesser T. , Lorenzen D. , Hennig P.
Published: October 2002

Photocurrent spectroscopy is applied for an analysis of both packaging-induced strain and strain-induced defect creation in InAlGaAs/GaAs high-power diode laser arrays. Strain profiles across 50 W diode lasers processed by different packaging procedures are measured and compared to model calculations. We demonstrate that packaging-induced strain giving rise to spectral shifts of the laser transition correlates with packaging-induced defects in the waveguide that are quantified via a sub-band gap absorption band. Packaging on a Cu–diamond multilayer heat spreader appears as optimized solution simultaneously minimizing strain and defect creation.
Growth of self-assembled GaN quantum dots via the vapor–liquid–solid mechanism
Authors: Hu C.-W. , Bell A. , Ponce F. A. , Smith D. J. , Tsong I. S. T.
Published: October 2002

Self-assembled nanometer-scale GaN quantum dots were fabricated on 6H–SiC(0001) substrates via the formation of Ga liquid droplets and their subsequent nitridation with a supersonic gas source seeded with NH3 molecules. The entire process was observed and controlled in situ and in real time in a low-energy electron microscope. The microstructure of the quantum dots was studied by high-resolution cross-sectional transmission electron microscopy illustrating the perfectly coherent wurtzite structure of GaN quantum dots with 5 nm base width. Spatially resolved cathodoluminescence spectra yield the characteristic band edge emission near 3.48 eV for larger size GaN dots.
Cascaded electro-optic scanning of laser light over large angles using domain microengineered ferroelectrics
Authors: Scrymgeour David A. , Sharan Alok , Gopalan Venkatraman , Gahagan Kevin T. , Casson Joanna L. , Sander Robert , Robinson Jeanne M. , Muhammad Fikri , Chandramani Premanand , Kiamilev Fouad
Published: October 2002

We present a device concept based on cascaded electro-optic deflection in a domain microengineered ferroelectric chip. In our design, large deflection angles are achieved by cascading several smaller scanners in a single ferroelectric chip, such that each successive scanner stage builds upon the deflection of the previous stage. We demonstrate the basic concept using a two-stage device fabricated in a single crystal wafer of ferroelectric LiTaO3. By operating the device using a specially designed programmable multichannel driver that provides ±1.1 kV per stage, a total scan angle of 25.4° at 5 kHz was demonstrated. Even larger angles of deflection are possible with additional scanner stages.
Self-organized strain engineering on GaAs (311)B: Template formation for quantum dot nucleation control
Authors: Gong Q. , Nötzel R. , Hamhuis G. J. , Eijkemans T. J. , Wolter J. H.
Published: October 2002

A matrix of closely packed cells develops during molecular-beam epitaxy of In0.35Ga0.65As on GaAs (311)B, due to strain-driven growth instability. The established lateral strain distribution generates a unique template that controls the nucleation and growth of InAs quantum dots (QDs). The QDs exhibit pronounced improvement of the structural and optical properties with efficient carrier transfer from the template. Thus, self-organization of a two-dimensionally connected quantum dot network is demonstrated.
Density-dependent critical currents in quantum-well-coupled weak links
Authors: Eckhause T. A. , Lehnert K. , Correa J. S. , Jorstad R. J. , Gwinn E. G. , Thomas Mason
Published: October 2002

We investigate a Josephson field-effect transistor in which the electron gas in an InAs quantum well serves as the weak link between superconducting Nb electrodes. We modulate the density Ns of electrons and the critical current Ic in the weak link by applying a voltage to an insulated gate. Measurements of the dependence of Ic on Ns are in good agreement with a model in which each occupied subband of the InAs quantum well makes an independent contribution to Ic. Inclusion of the nonparabolic band structure in InAs is crucial to this agreement.
Platinum-assisted phase transition in bismuth-based layer-structured ferroelectric CaBi4Ti4O15 thin films
Authors: Kato Kazumi , Suzuki Kazuyuki , Fu Desheng , Nishizawa Kaori , Miki Takeshi
Published: October 2002

The phase transition of nonferroelectric pyrochlore to ferroelectric perovskite in CaBi4Ti4O15 thin films depends on platinum bottom electrodes. Rather than the strain and crystallinity of the bottom electrode, matching of the atomic arrangement to the Ca–Bi–Ti–O thin films is predominant. CaBi4Ti4O15 thin films crystallized on (200)-oriented platinum at 650 °C showed c-axis orientation. In contrast, thin films crystallized on highly crystalline (111)-oriented platinum at the same temperature contained pyrochlore grains which were about several tens of nanometers in diameter and located in the interface region. They showed P–V hysteresis loops. The remanent polarization and coercive electric field depended on platinum top electrode size.
Mechanics of carbon nanotubes
Authors: Qian, Dong , Wagner, and Gregory J , Liu Wing Kam , Yu Min-Feng , Ruoff Rodney S
Published: October 2002

Soon after the discovery of carbon nanotubes, it was realized that the theoretically predicted mechanical properties of these interesting structures–including high strength, high stiffness, low density and structural perfection–could make them ideal for a wealth of technological applications. The experimental verification, and in some cases refutation, of these predictions, along with a number of computer simulation methods applied to their modeling, has led over the past decade to an improved but by no means complete understanding of the mechanics of carbon nanotubes. We review the theoretical predictions and discuss the experimental techniques that are most often used for the challenging tasks of visualizing and manipulating these tiny structures. We also outline the computational approaches that have been taken, including ab initio quantum mechanical simulations, classical molecular dynamics, and continuum models. The development of multiscale and multiphysics models and simulation tools naturally arises as a result of the link between basic scientific research and engineering application; while this issue is still under intensive study, we present here some of the approaches to this topic. Our concentration throughout is on the exploration of mechanical properties such as Young’s modulus, bending stiffness, buckling criteria, and tensile and compressive strengths. Finally, we discuss several examples of exciting applications that take advantage of these properties, including nanoropes, filled nanotubes, nanoelectromechanical systems, nanosensors, and nanotube-reinforced polymers. This review article cites 349 references.
Sonic band structure and localized modes in a density-modulated system: Experiment and theory
Authors: Carr Christopher , Yu Roger
Published: October 2002

The sonic passing bands and stopping gaps of a quasi-one-dimensional air tube with modulated mass density were studied experimentally and theoretically. Some gap modes whose wave functions are strongly localized near the ends of the air tube were also found. The simple experiment can be used as a demonstration of band structure in an upper-division physics course.
Halofuginone inhibition of COL1A2 promoter activity via a c‐Jun–dependent mechanism
Authors: McGaha Tracy L. , Kodera Takao , Spiera Harry , Stan Alexandru C. , Pines Mark , Bona Constantin A.
Published: October 2002

Objective

The naturally occurring compound halofuginone has been shown to antagonize collagen synthesis by fibroblasts both in vitro and in vivo. We previously demonstrated that this inhibitory property was related to the ability of halofuginone to disrupt transforming growth factor β signal transduction. The present study further analyzed the ability of halofuginone to affect transcription factors that can regulate type I collagen gene expression by examining its effect on c‐Jun, the negative regulator of collagen gene transcription.

Methods

The phosphorylation state of c‐Jun in the presence of halofuginone was examined via direct Western blotting, and the transcriptional activity of the activator protein 1 (AP‐1) binding element via electrophoretic mobility shift assay and luciferase reporter assay. We determined whether the effect of halofuginone on collagen synthesis was dependent on the presence of c‐Jun by ectopic expression of a wild‐type or dominant‐negative c‐Jun construct in the presence of halofuginone and assaying α2(I) collagen promoter strength via luciferase reporter assay. The effect of halofuginone on α2(I) collagen message levels in fibroblasts when wild‐type or dominant‐negative c‐Jun was overexpressed was determined. We also determined whether halofuginone had an effect on the phosphorylation state of c‐Jun in the skin of TSK/+ mice via immunohistochemistry.

Results

Treatment of fibroblasts with 10−8M halofuginone enhanced basal and mitogen‐mediated phosphorylation of c‐Jun in culture. This elevated phosphorylation of c‐Jun correlated with enhanced DNA binding and transcriptional activation of an AP‐1 complex consisting of c‐Jun and Fos but lacking the c‐Jun antagonist JunB. Overexpression of c‐Jun enhanced in a dose‐dependent manner the ability of halofuginone to inhibit the activity of a luciferase reporter construct under control of the −3200‐bp to +54‐bp COL1A2 promoter, whereas the expression of a dominant‐negative c‐Jun construct abolished this effect. Northern blotting showed that overexpression of c‐Jun enhanced the ability of halofuginone to reduce collagen α2(I) messenger RNA levels in fibroblasts, whereas expression of the dominant‐negative c‐Jun abolished this effect. Topical administration of a halofuginone‐containing cream for 20 days to TSK mice, which spontaneously develop dermal fibrosis, greatly increased the phosphorylated form of c‐Jun in the skin; this was followed by a decrease in skin thickness and type I collagen messenger RNA expression.

Conclusion

Our findings illustrate the powerful down‐regulatory property of c‐Jun toward type I collagen and establish that halofuginone exerts its effect on collagen synthesis in a c‐Jun–dependent manner.
Involvement of the interferon‐γ–induced T cell–attracting chemokines, interferon‐γ–inducible 10‐kd protein (CXCL10) and monokine induced by interferon‐γ (CXCL9), in the salivary gland lesions of patients with Sjögren's syndrome
Authors: Ogawa Noriyoshi , Ping Li , Zhenjun Li , Takada Yukiko , Sugai Susumu
Published: October 2002

Objective

To elucidate the mechanism of the development of T cell infiltrates in the salivary glands of patients with Sjögren's syndrome (SS), we studied T cell–attracting chemokines and their receptors.

Methods

The expression of the T cell–attracting chemokines, interferon‐γ (IFNγ)–inducible 10‐kd protein (IP‐10; also called CXCL10), monokine induced by IFNγ (Mig; also called CXCL9), and stromal cell–derived factor 1 (SDF‐1; also called CXCL12), in salivary glands from SS patients was investigated by polymerase chain reaction–enzyme‐linked immunosorbent assay (ELISA). Cells that produce chemokines and lymphocytes that express chemokine receptors were identified by immunohistochemistry. The production of IP‐10 and Mig proteins by salivary epithelial cells in response to IFNγ was determined by ELISA.

Results

Expression of IP‐10 and Mig messenger RNA (mRNA) was significantly up‐regulated in SS salivary glands compared with normal salivary glands (both P < 0.01). There was no significant difference in SDF‐1 mRNA expression between the SS and normal salivary glands. IP‐10 and Mig proteins were predominantly expressed in the ductal epithelium adjacent to lymphoid infiltrates. Most of the CD3+ infiltrating lymphocytes in dense periductal foci expressed CXCR3, the receptor for IP‐10 and Mig. IFNγ induced the production of high levels of IP‐10 and Mig proteins from cultured SS salivary epithelial cells.

Conclusion

These findings suggest that IFNγ stimulates the production of IP‐10 and Mig in the SS ductal epithelium, and that IP‐10 and Mig are involved in the accumulation of T cell infiltrates in the SS salivary gland. Chemokines or chemokine receptors could be a rational new therapeutic target in SS.
Received level detection accuracy in DS‐CDMA system
Authors: Miki Yoshinori , Fujii Teruya
Published: October 2002

In cellular mobile communications, the mobile station must detect the received level so as to determine the position of the mobile station. In a broadband DS‐CDMA system, RAKE reception is usual since the paths can be separated. Thus, the detection accuracy should be improvable by the path diversity effect. This paper considers a DS‐CDMA system, and the accuracy of the received level detection is analyzed theoretically and by computer simulation for the case in which both path diversity and antenna space diversity are applied. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(2): 51–60, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.1153
An experimental evaluation of ice cover effects on the dynamic behaviour of a concrete gravity dam
Authors: Paultre Patrick , Proulx Jean , Carbonneau Charles
Published: October 2002

An extensive forced‐vibration testing programme has been carried out on an 84‐m concrete gravity dam located in northeastern Québec, Canada. The dam was subjected to a harmonic load on the crest in summer and severe winter conditions with temperatures ranging from −10°C to −15°C and a 1.0–1.5m ice cover. Acceleration and hydrodynamic frequency responses were obtained in different locations on the dam and in the reservoir. The main objective of the repeated tests was to investigate the effects of the ice cover on the dynamic behaviour of the dam–reservoir–foundation system, by comparing summer and winter results. Modifications in damping and resonance frequencies were observed, as well as an additional resonance that was attributed to an interaction of the dam with the ice cover. These findings provided a reliable and unique database for the investigations of dam–reservoir–foundation interaction and, in particular, the ice‐cover effects for dams located in northern regions. Copyright © 2002 John Wiley & Sons, Ltd.
Increase in power of transmission‐disequilibrium tests for quantitative traits
Authors: Malkin Ida , Ginsburg Emil , Elston Robert C.
Published: October 2002

Allison ([1997] Am. J. Hum. Genet. 60:676–690) proposed four versions of the transmission‐disequilibrium test (TDT) for quantitative traits when there is extreme‐threshold sampling, i.e., the trios having an offspring trait value between a priori defined thresholds are excluded from the analysis. Keeping intact the ideology and construction of these tests, we propose here an extreme‐offspring design for the trios: for each parent pair of which at least one is heterozygous at a marker locus, the offspring having the most extreme trait value is selected for the trio. Our simulation studies show that the effect of the extreme‐offspring design can be quite substantial (up to 30% increase in test power), and that the increase is greater for smaller values of the association parameter and for traits with smaller heritability: just those cases where the increase in power is especially desirable. Genety. Epidemiol. 23:234–244, 2002. © 2002 Wiley‐Liss, Inc.
Intrafamilial correlation of clinical manifestations in neurofibromatosis 2 (NF2)
Authors: Zhao Y. , Kumar R.A. , Baser M.E. , Evans D.G.R. , Wallace A. , Kluwe L. , Mautner V.F. , Parry D.M. , Rouleau G.A. , Joe H. , Friedman J.M.
Published: October 2002

Measuring correlation in clinical traits among relatives is important to our understanding of the causes of variable expressivity in Mendelian diseases. Random effects models are widely used to estimate intrafamilial correlations, but such models have limitations. We incorporated survival techniques into a random effects model so that it can be used to estimate intrafamilial correlations in continuous variables with right censoring, such as age at onset. We also describe a negative‐binomial gamma mixture model to determine intrafamilial correlations of discrete (e.g., count) data. We demonstrate the utility of these methods by analyzing intrafamilial correlations among patients with neurofibromatosis 2 (NF2), an autosomal‐dominant disease caused by mutations of the NF2 tumor‐suppressor gene. We estimated intrafamilial correlations in age at first symptom of NF2, age at onset of hearing loss, and number of intracranial meningiomas in 390 NF2 nonprobands from 153 unrelated families. A significant intrafamilial correlation was observed for each of the three features: age at onset (0.35; 95% confidence interval (CI) 0.23–0.47), age at onset of hearing loss (0.51; 95% CI, 0.35–0.64), and number of meninginomas (0.29; 95% CI, 0.15–0.43). Significant correlations were also observed for age at first symptom within NF2 families with truncating mutations (0.41; 95% CI, 0.06–0.68) or splice‐site mutations (0.29; 95% CI, 0.03–0.51), for age at onset of hearing loss within families with missense mutations (0.67; 95% CI, 0.18–0.89), and for number of meningiomas within families with splice‐site mutations (0.39; 95% CI, 0.13–0.66). Our findings are consistent with effects of both allelic and nonallelic familial factors on the clinical variability of NF2. Genet. Epidemiol. 23:245–259, 2002. © 2002 Wiley‐Liss, Inc.