bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrical, optical and photoconductive properties of Poly(dibenzo‐18‐crown‐6)
Authors: Qasrawi A. F. , Cihaner A. , Önal A. M. 
Published: January 2004

AbstractTo investigate the energy levels, absorption bands, band gap, dominant transport mechanisms, recombination mechanisms and the free carrier life time behavior of poly‐dibenzo‐18‐crown‐6, poly‐DB18C6, films, the dark electrical conductivity in the temperature range of 200‐550 K, the absorbance and photocurrent spectra, the photocurrent –illumination intensity and time dependence at 300 K were studied. The dark electrical conductivity measurements revealed the existence of three energy levels located at 0.93, 0.32 and 0.76 eV below the tails of the conduction band. The main transport mechanism in the dark was found to be due to the thermal excitation of charge carriers and the variable range hopping above and below 260 K, respectively. The photocurrent and absorbance spectra reflect a band gap of 3.9 eV. The photocurrent ‐illumination intensity dependence reflects the sublinear, linear and supralinear characters indicating the decrease, remaining constant and increase in the free electron life time that in turn show the bimolecular, strong and very strong recombination characters at the surface under the application of low, moderate and high illumination intensity, respectively. A response time of 25.6 s was calculated from the decay of Iph‐time dependence. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoconductivity in Tl4S3 layered single crystals
Authors: Ashraf I. M. , Elshaikh H. A. , Badr A. M. 
Published: January 2004

AbstractPhotoconductivity measurements are carried out in this work for single crystals of Tl4S3 compound by using both pulsed excitation (a.c) and steady state (a.c) methods in order to elucidate the nature of photoconductivity (PC) in this compound. Results are reported in the temperature range from 77 to 300 K, excitation intensity range from 1800 to 3300 Lux, applied voltage range from 8 to 14 V, and wavelength range from 840 to 1450 nm. Both of the ac‐photoconductivity (ac‐PC) and the spectral distribution of the photocurrent are studied at different values of light intensity, applied voltage and temperature. Dependencies of carrier lifetime on light intensity, applied voltage and temperature are also investigated as results of the ac‐PC measurements. By using the results of the dc‐photoconductivity (dc‐PC) measurements, the temperature dependence of the energy gap width is described. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of lattice defects in divalent lattices by incorporating trivalent ions in biominerals: An EPR study of Cr(III) in zinc(II) potassium phosphate hexahydrate
Authors: Anandalakshmi H. , Venkatesan R. , Sambasiva Rao P. 
Published: January 2004

AbstractIn order to understand the effect of charge compensating vacancies on the number, orientation and magnitude of D‐tensors, single crystal EPR measurements have been carried out with Cr(III) in zinc(II) potassium phosphate hexahydrate at room temperature. During crystal rotations, a maximum of 6/7 resonance lines or a minimum of 2 is noticed. Crystal rotations done in the three orthogonal planes have yielded spin Hamiltonian parameters for one site with: gxx=1.969, gyy= 1.995, gzz= 2.107; Dxx= 66.2 mT; Dyy= 91.7 mT, and Dzz=‐157.9 mT. The powder EPR spectrum indicates a very broad line at g = 8, without any extra resonances from 0 to 650 mT both at room temperature and 77 K. The reason may be that due to large zero field splitting, the resonance at g = 2 is shifted to g = 8 position and the other resonances are below 0 or above 650 mT. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis of the crystal structures of 1,3‐di‐tert‐butyl‐2,3‐dihydro‐1H‐1,3,2‐diazasilol‐2‐ylidene and 1,3‐di‐tert‐butyl‐2,2‐dichloro‐1,3‐diaza‐2‐sila‐4‐cyclopentene
Authors: Becker J. S. , Staples R. J. , Gordon R. G. 
Published: January 2004

AbstractThe crystal structures of the title compounds, 1,3‐di‐tert‐butyl‐2,3‐dihydro‐1H‐1,3,2‐diazasilol‐2‐ylidene, C10H20N2Si (1) and 1,3‐di‐tert‐butyl‐2,2‐dichloro‐1,3‐diaza‐2‐sila‐4‐cyclopentene, C10H20N2SiCl2 (3) were solved and are reported. Compound (1) crystallized in space group P mmn and each molecule has a mirror plane, which bisects the C‐C backbone of the N‐C‐C‐N framework. Compound (1) was also found to have a 2‐fold twin component. In compound (3) the space group P 21/m results with the mirror plane passing through the N‐C‐C‐N backbone. We compare these structures with the gas phase determination previously reported for (1) and the incomplete single crystal data for (3). (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Differences in the embryonic expression patterns of mouse Foxf1 and ‐2 match their distinct mutant phenotypes
Authors: Ormestad Mattias , Astorga Jeanette , Carlsson Peter 
Published: January 2004

AbstractMurine genes encoding the forkhead transcription factors Foxf1 and ‐2 are both expressed in derivatives of the splanchnic mesoderm, i.e., the mesenchyme of organs derived from the primitive gut. In addition, Foxf2 is also expressed in limbs and the central nervous system. Targeted mutagenesis of Foxf1 and ‐2 suggests that Foxf1 is the more important of the two mammalian FoxF genes with early embryonic lethality of null embryos and a haploinsufficiency phenotype affecting foregut‐derived organs. In contrast, the only reported defect in Foxf2 null embryos is cleft palate. To investigate if the differences in mutant phenotype can be attributed to nonoverlapping expression patterns or if distinct functions of the encoded proteins have to be inferred, we analyzed the early embryonic expression of Foxf2 and compared it with that of the better investigated Foxf1. We find that in the early embryo, Foxf1 is completely dominating—in terms of expression—in extraembryonic and lateral plate mesoderm, consistent with the malformations and early lethality of Foxf1 null mutants. Along the developing gut, Foxf1 is highly expressed throughout, whereas Foxf2 expression is concentrated to the posterior part—fitting the foregut haploinsufficiency phenotypes of Foxf1 mutants. Foxf2, on the other hand, is more prominent than Foxf1 in mesenchyme around the oral cavity, as would be predicted from the cleft palate phenotype. The differences in expression pattern also highlight areas where defects should be sought for in the Foxf2 mutant, for example limbs, the posterior gut, genitalia, and derivatives of the neural crest mesenchyme. Developmental Dynamics 229:328–333, 2004 © 2003 Wiley‐Liss, Inc.
Amphibian cardiac troponin I gene's organization, developmental expression, and regulatory properties are different from its mammalian homologue
Authors: Warkman Andrew S. , Atkinson Burr G. 
Published: January 2004

AbstractIn mammals, the expression of the troponin I‐slow (TnIs) isoform is predominant in the heart during embryogenesis and, shortly after birth, is replaced by the cardiac‐specific isoform, TnIc; a developmental switch thought to be mediated by thyroid hormone. Whereas, in Xenopus, TnIc is expressed at the onset of heart formation and is the only TnI isoform expressed in the heart. Herein, we demonstrate that the expression patterns of these genes appear to be common within the anuran lineage and, unlike their mammalian counterparts, are not affected by thyroid hormone. To elucidate the regulatory mechanism(s) governing the expression of the amphibian TnIc gene, we characterized the TnIc gene from Rana catesbeiana and used its 5′‐flanking region to drive expression of green fluorescent protein in the Xenopus transgenic system. Our results demonstrate that a 300‐bp minimal promoter containing intact GATA and CArG‐box elements is sufficient to drive expression of this reporter gene in a pattern that mimics, both spatially and temporally, the expression of the endogenous Xenopus TnIc gene. Developmental Dynamics 229:275–288, 2004.© 2003 Wiley‐Liss, Inc.
Isolation and expression of the homeobox gene Gbx1 during mouse development
Authors: Rhinn Muriel , Lun Klaus , Werner Michaela , Simeone Antonio , Brand Michael 
Published: January 2004

AbstractIn zebrafish, gbx1 and otx2 are among the earliest genes expressed in the neuroectoderm, dividing it into an anterior and a posterior domain with a common border that marks the midbrain–hindbrain boundary (MHB) primordium. Here, we describe the sequence and expression pattern of Gbx1 in mouse. The first transcripts are found at embryonic day 7.75 in the hindbrain. Later on, expression of Gbx1 is detectable in the hindbrain (rhombomeres 2 to 7), spinal cord, optic vesicles, and in the ventral telencephalon. In mouse, Gbx1 expression is not observed at the MHB as is the case during early zebrafish development. We suggest that an evolutionary switch occurred: in mouse Gbx2 is involved in the early specification of the MHB primordium, whereas in zebrafish, gbx1 is required instead of gbx2. Developmental Dynamics 229:334–339, 2004. © 2004 Wiley‐Liss, Inc.
Pilot morpholino screen in Xenopus tropicalis identifies a novel gene involved in head development
Authors: Kenwrick Sue , Amaya Enrique , Papalopulu Nancy 
Published: January 2004

AbstractThe diploid frog X. tropicalis has recently been adopted as a model genetic system, but loss‐of‐function screens in Xenopus have not yet been performed. We have undertaken a pilot functional knockdown screen in X. tropicalis for genes involved in nervous system development by injecting antisense morpholino (MO) oligos directed against X. tropicalis mRNAs. Twenty‐six genes with primary expression in the nervous system were selected as targets based on an expression screen previously conducted in X. laevis. Reproducible phenotypes were observed for six and for four of these, a second MO gave a similar result. One of these genes encodes a novel protein with previously unknown function. Knocking down this gene, designated pinhead, results in severe microcephaly, whereas, overexpression results in macrocephaly. Together with the early embryonic expression in the anterior neural plate, these data indicate that pinhead is a novel gene involved in controlling head development. Developmental Dynamics 289–299, 2004. © 2003 Wiley‐Liss, Inc.
Identification of the mammary line in mouse by Wnt10b expression
Authors: Veltmaat Jacqueline M. , Van Veelen Wendy , Thiery Jean Paul , Bellusci Saverio 
Published: January 2004

AbstractMammogenesis in rabbit, rat, and human begins with the formation of an elevated ectodermal ridge in the embryo. Attempts to demonstrate a morphologically or histologically equivalent mammary line in the mouse have yielded controversial results. We show here that a mammary line exists in the mouse embryo at embryonic day (E) 11.25 as a concise line of Wnt10b expression and a broader band of Wnt6 expression in the surface ectoderm, between the subaxillary and suprainguinal region of each flank. Additional streaks of Wnt10b expression in the axillary and inguinal region join the mammary line on the flank slightly later. Expression of Wnt10b and Wnt6 becomes restricted to the placodes within 1.5 days. The ectoderm of the mammary line is organized as a pseudostratified epithelium connecting the developing mammary placodes at around E11.5, whereas all other surface ectoderm is single‐layered. Thus, the mammary line expressing Wnt10b defines a distinct ectodermal region that we consider the equivalent of the ectodermal ridge in, for example, rabbit. To date, the formation of the mammary line expressing Wnt10b is the earliest discernible ectodermal event in murine embryonic mammary gland development. Developmental Dynamics 229:349–356, 2004. © 2004 Wiley‐Liss, Inc.
Embryonic myogenesis pathways in muscle regeneration
Authors: Zhao Po , Hoffman Eric P. 
Published: January 2004

AbstractEmbryonic myogenesis involves the staged induction of myogenic regulatory factors and positional cues that dictate cell determination, proliferation, and differentiation into adult muscle. Muscle is able to regenerate after damage, and muscle regeneration is generally thought to recapitulate myogenesis during embryogenesis. There has been considerable progress in the delineation of myogenesis pathways during embryogenesis, but it is not known whether the same signaling pathways are relevant to muscle regeneration in adults. Here, we defined the subset of embryogenesis pathways induced in muscle regeneration using a 27 time‐point in vivo muscle regeneration series. The embryonic Wnt (Wnt1, 3a, 7a, 11), Shh pathway, and the BMP (BMP2, 4, 7) pathway were not induced during muscle regeneration. Moreover, antagonists of Wnt signaling, sFRP1, sFRP2, and sFRP4 (secreted frizzled‐related proteins) were significantly up‐regulated, suggesting active inhibition of the Wnt pathway. The pro‐differentiation FGFR4 pathway was transiently expressed at day 3, commensurate with expression of MyoD, Myogenin, Myf5, and Pax7. Protein verification studies showed fibroblast growth factor receptor 4 (FGFR4) protein to be strongly expressed in differentiating myoblasts and newly formed myotubes. We present evidence that FGF6 is likely the key ligand for FGFR4 during muscle regeneration, and further suggest that FGF6 is released from necrotic myofibers where it is then sequestered by basal laminae. We also confirmed activation of Notch1 in the regenerating muscle. Finally, known MyoD coactivators (MEF2A, p/CIP, TCF12) and repressors (Twist, Id2) were strongly induced at appropriate time points. Taken together, our results suggest that embryonic positional signals (Wnt, Shh, and BMP) are not induced in postnatal muscle regeneration, whereas cell‐autonomous factors (Pax7, MRFs, FGFR4) involving muscle precursor proliferation and differentiation are recapitulated by muscle regeneration. Developmental Dynamics 229:380–392, 2004. © 2004 Wiley‐Liss, Inc.
Ror2 knockout mouse as a model for the developmental pathology of autosomal recessive Robinow syndrome
Authors: Schwabe Georg C. , Trepczik Britta , Süring Kathrin , Brieske Norbert , Tucker Abigail S. , Sharpe Paul T. , Minami Yasuhiro , Mundlos Stefan 
Published: January 2004

AbstractRobinow syndrome (RS) is a human dwarfism syndrome characterized by mesomelic limb shortening, vertebral and craniofacial malformations and small external genitals. We have analyzed Ror2‐/‐ mice as a model for the developmental pathology of RS. Our results demonstrate that vertebral malformations in Ror2‐/‐ mice are due to reductions in the presomitic mesoderm and defects in somitogenesis. Mesomelic limb shortening in Ror2‐/‐ mice is a consequence of perturbed chondrocyte differentiation. Moreover, we show that the craniofacial phenotype is caused by a midline outgrowth defect. Ror2 expression in the genital tubercle and its reduced size in Ror2‐/‐ mice makes it likely that Ror2 is involved in genital development. In conclusion, our findings suggest that Ror2 is essential at multiple sites during development. The Ror2‐/‐ mouse provides a suitable model that may help to explain many of the underlying developmental malformations in individuals with Robinow syndrome. Developmental Dynamics 229:400–410, 2004, © 2004 Wiley‐Liss, Inc.
A high‐speed HMM VLSI module with block parallel processing
Authors: Yoshizawa Shingo , Miyanaga Yoshikazu , Yoshida Norinobu 
Published: January 2004

AbstractThis paper considers the continuous distribution HMM and discusses speed improvement by parallel processing and VLSI design, aiming at the realization of a high‐speed speech recognition LSI. The continuous distribution HMM has high recognition performance. But a large amount of computation is required for the calculation of the output probability, and speed improvement is highly desirable. Regarding speed improvement of the output probability calculation, this paper proposes blockwise parallel processing and an architecture for performance. The minimum optimal bit width is investigated for recognition by fixed‐point operations. Based on the proposed architecture, VLSI design for an HMM is performed and the result is evaluated. It is shown that the proposed architecture has sufficient power to construct a recognition system that can respond in real time, requiring 3 ms for the recognition processing of 100 words. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 87(5): 12–23, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10099
Simplified training algorithm for hierarchical hidden Markov models
Authors: Ueda Nobuhisa , Sato Taisuke 
Published: January 2004

AbstractThis paper considers an extension of the hidden Markov model, called the hierarchical hidden Markov model, and proposes an EM algorithm and an approximate algorithm. The EM algorithm proposed in this paper differs from the existing training algorithm, which is called the Baum–Welch algorithm, and guarantees that the likelihood is always increased by updating the parameters. The approximate algorithm has the advantage that it can be applied to problems in which observation of the training sentence and training of the parameters proceed in parallel. These algorithms and their derivations are simplified, compared to the existing training algorithm, by using stochastic context‐free grammar. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 87(5): 59–69, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10172
Robust scheme of an indirect MRACS system taking into account the presence of deterministic disturbances
Authors: Suzuki Yoshiaki , Suzuki Takashi , Itamiya Keietsu 
Published: January 2004

AbstractThis paper presents a method for the design of an indirect model reference adaptive control (MRAC) system for a plant with deterministic disturbances, robust to modeling errors due to unmodeled dynamics and observation noise. In the proposed method, the structure of the controller is determined on the basis of the internal model principle to reject the deterministic disturbance, and its parameters are adjusted by using the estimated plant parameters. Robustness to the modeling errors is ensured by the use of the adaptive law with a dead zone and a fixed compensator of integral type. The adaptive law prevents the adjustable parameters from drifting and the fixed compensator improves the control performance degraded by the use of the dead zone. Stability of the MRAC system is analyzed using the concept of the ℒ︁2δ norm and the Bellman–Gronwall lemma, based on the properties guaranteed by the adaptive law. Effectiveness of the proposed method is demonstrated by the simulation carried out for a plant with second‐order nominal part and a step disturbance. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 146(4): 65–75, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10190
Calculation of the loss‐minimum configuration in the IEEJ local power system model
Authors: Hayashi Yasuhiro , Matsuki Junya , Kurihara Ikuo 
Published: January 2004

AbstractIn Japan, local power systems (77 kV) are served from the 275‐ or 154‐kV substations. For enhancement of power supply reliability, the transmission lines are connected to several substations, and the operational configuration is radial. The local power system's configuration is determined by connecting and disconnecting transmission lines so as to keep the radial structure and satisfy the operation constraints. When a local power system has a number of transmission lines, many configuration candidates occur. Recently, an IEEJ committee made a practical scale local system model (IEEJ Local System Model). Since the IEEJ Local System Model has 76 transmission lines, the total number of configuration candidates is 276 (approximately 7.5 × 1022). In this paper, the authors try to strictly obtain the loss‐minimum configuration under constraints such as substation capacity, line capacity, and radial structure in the IEEJ Local System Model. In order to obtain the optimal configuration, a new computation algorithm is proposed. In the proposed algorithm, the configuration determination problem is replaced as two combinatorial optimization problems based on the operational constraints [(1) substation capacity, (2) line capacity, and (3) radial structure]. One combinatorial optimization problem (subproblem 1) is to pick up all partial configurations so as to minimize total line loss under the substation capacity constraint. By using the enumeration method, subproblem 1 is solved. Subproblem 2 is solved by using the reduced ordered binary decision diagram (ROBDD). Since the proposed method is based on enumeration and Boolean function, the optimality of obtained solution is guaranteed. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 146(4): 34–42, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10226
Insulation characteristics of SF6 gas for nonstandard impulse voltage polarity reversal pulse waveforms
Authors: Rokunohe Toshiaki , Suzuki Toshiyuki , Yamagiwa Tokio , Yuasa Sadayuki , Okabe Shigemitsu 
Published: January 2004

AbstractEvaluation of insulation strength for lightning surge that actually enters into substations is important in estimating insulation reliability of gas‐insulated equipment. The standard lightning impulse voltage (1.2/50 µs) is used for factory tests. However, the actual lightning surge waveforms in substations are complex and are usually superimposed with various oscillations. Insulation characteristics of SF6 gas as a function of such complex voltages have not been sufficiently clarified.This paper deals with gap breakdown characteristics in SF6 gas under submicrosecond pulses. Breakdown voltages are lower under a polarity reversal condition than under a monopolarity condition. The cause of this difference is discussed while observing discharge propagation using an image converter camera. The electrode size effect is also discussed. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 146(4): 18–25, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10246
Development of a laser wavefront sensor for measurement of discharges in air
Authors: Fukuchi Tetsuo , Yamaguchi Yukihiro , Nayuki Takuya , Nemoto Koshichi , Uchino Kiichiro 
Published: January 2004

AbstractA laser wavefront sensor of the Shack‐Hartmann type capable of simultaneous measurement at two wavelengths was constructed. The sensor uses a single optical path, and is suited for applications such as high‐voltage discharges in air, in which large insulation distances are necessary. The sensor was used to detect optical path differences due to an impulse discharge in air across a needle–plane electrode gap of gap length 17 mm. Optical path differences were measured at laser wavelengths of 532 and 1064 nm at 1.6 µs after insulation breakdown across the gap. From the difference in optical path differences at the two wavelengths, a line‐integrated electron density distribution in the direction perpendicular to the gap was obtained near the high‐voltage electrode. The distribution had a peak value of 1.4 × 1020m−2 and a full width at half maximum of 4.4 mm. Because of the coverage of a large observation area including the entire gap, the spatial resolution was 1.4 mm, which was inadequate to obtain the precise form of the electron density distribution. However, the results show the possibility of applying laser wavefront sensing to electron density measurement. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 146(4): 10–17, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10247