bluuebunny/crossref_metadata_2025 huggingface dataset:
High Performance of Silicon Oxide Selective Etching Using F2 Gas and Graphite Instead of Perfluorinated Compound Gases
Authors: Nagai Mikio , Hori Masaru , Goto Toshio
Published: February 2005

We have demonstrated an environmentally benign SiO2 selective-etching process in a magnetron plasma using a graphite target and F2 gas instead of perfluorinated compound (PFC) gases. The top electrode of graphite was supplied with power from two different 13.56 MHz and 450 kHz RF sources. The amount of C-based species in the plasma was controlled by the 450 kHz RF source bias voltage. The F atom density was controlled in the plasma by changing the amount of F2 feed gas. High SiO2/resist selectivity and a vertical etching pattern profile were realized. Microtrenching was suppressed by the injection of high energy electrons.
Si(111)-3 × 1-Ag Reconstruction Studied In Situ at Elevated Temperatures by Second-Harmonic Generation
Authors: Deng Dongmei , Suzuki Takanori
Published: February 2005

Si(111)-3 × 1-Ag reconstruction at elevated temperatures during Ag adsorption and desorption has been identified for the first time by optical second-harmonic generation (SHG). Si(111)-3 × 1-Ag may be described by an unstable distribution of structures of p1 symmetry. The largest Si(111)-3 × 1-Ag area observed in the range from 500°C to 600°C during Ag desorption from Si(111)-√3×√3-Ag is ascribed to a nearly full Si(111)-3 × 1-Ag surface.
Surface-Enhanced Nonresonance Raman Scattering of Rhodamine 6G Molecules Adsorbed on Gold Nanorod Films
Authors: Suzuki Mototsugu , Niidome Yasuro , Terasaki Nao , Inoue Kazuma , Kuwahara Yutaka , Sunao Yamada* Sunao Yamada*
Published: February 2005

We found a new method for the preparation of gold nanorod and nanosphere films. The nanoparticle films could be formed at the liquid-liquid interface between aqueous and hexane solutions and were almost monolayers. Surface-enhanced Raman scattering (SERS) spectra of rhodamine 6G under the nonresonance condition were measured using these films as SERS substrates. It is experimentally demonstrated that nanorods with a higher aspect ratio are more effective in SERS enhancement.
A Novel Optical Packet Generator with A Continuously Changeable Bit-Rate and Packet Length
Authors: Shin Seoyong
Published: February 2005

We propose and demonstrate a novel high-speed programmable bit-rate and packet length optical packet generator that can be used in optical transparent packet switching networks. The generator uses optical bundles composed of a fixed number of optical short pulses with a certain repetition rate as a source to produce an optical packet at the fiber-optic recirculating loop. The length and bit-rate of the packet can be changed continuously by changing respectively the number of optical short pulses and their repetition rate in the bundle. For robustness, simplicity, and compactness, we use the gain-switching technique for the generation of optical short pulses. We experimentally demonstrate the generation of various kinds of optical packets with different lengths and bit-rates.
New Route to Fabricate Ferromagnetic Semiconductors without Transition Metal Elements
Authors: Seike Masayoshi , Kenmochi Kazuhide , Sato Kazunori , Yanase Akira , Katayama-Yoshida Hiroshi
Published: February 2005

We propose a new route for ferromagnetic diluted magnetic semiconductors by controlling the impurity-band width (W) and the electron-correlation energy (U) in the partially occupied impurity band in the condition of highly correlated electron system (U>W). Based upon first-principles calculations of K2(S,Si) and K2(S,Ge), we demonstrate that transparent, half-metallic and room-temperature ferromagnetic DMS could be designed even without transition metal elements. The results show that it is possible to fabricate the room-temperature ferromagnets in K2(S,Si) and K2(S,Ge) around 8 at%-impurity concentration.
Emission Characteristics of Extreme Ultraviolet Radiation from CO2 Laser-Produced Xenon Plasma
Authors: Tanaka Hiroki , Akinaga Koji , Takahashi Akihiko , Okada Tatsuo
Published: February 2005

We propose a CO2 laser-produced plasma as the extreme ultraviolet (EUV) light source for a future optical lithography system. The EUV radiation around 13.5 nm was generated by focusing the laser beam from a transversely-excited atmospheric CO2 laser (4 J, 50 ns full width at half-maximum (FWHM)) on a Xe gas target and a Xe cryogenic target. The EUV energy was measured by a Flying Circus II detecting system, and an output energy of more than 3 mJ/pulse and an conversion efficiency of more than 0.1% per 2π sr at 13.5 nm were obtained. These values are comparable to those of Nd:YAG laser-produced plasma, indicating the potential scalability of the EUV light source using a CO2 laser produced plasma.
Domain Structure of a Magnetic Head Observed by Strain Imaging
Authors: Takata Keiji
Published: February 2005

Magnetic domain structures in a magnetic head of a hard disk drive were observed by strain imaging. When a magnetic material is subjected to an external magnetic field, a strain is generated in the material. We can observe domain structures by imaging the strain using a scanning probe microscope. We proved by strain imaging of the magnetic head that magnetic structures in the top pole tip of the writing head were divided into two domains by the center axis, and the boundary was split in the interface between the sputtering and plating layers. The structures in the deep portions of the pole appeared in the images. These images were formed by the strains caused by magnetic forces.
Proposal of Tunable Hollow Waveguide Distributed Bragg Reflectors
Authors: Sakurai Yasuki , Koyama Fumio
Published: February 2005

We propose a novel tunable distributed Bragg reflector (DBR) consisting of a grating loaded slab hollow waveguide with a variable air core. A change in an air core thickness of the tunable hollow waveguide gives us a large shift of over 100 nm in Bragg wavelength due to a change of several percents in a propagation constant. In order to obtain the high reflectivity and wide tunability of the tunable hollow waveguide DBR, the optimisation of the grating depth and grating length is carried out with minimizing radiation loss and distortion of reflection spectra induced by the corrugation. The modelling result shows a possibility of wide tunability of several tens nm with maintaining a high reflectivity of more than 90% without noticeable radiation loss and distortion of reflection spectra. We expect various device applications of the proposed tunable hollow waveguide DBR, which may include tunable band-pass filters, gain equalizers and dispersion compensators.
Supercontinuum Generation and Pulse Compression in Short Fibers for Optical Pulses Generated by 1.5 µm Optical Parametric Oscillator
Authors: Katayama Takeo , Kawaguchi Hitoshi
Published: February 2005

Supercontinuum (SC) optical pulses in the 1.5 µm region with a spectral width of approximately 300 nm are generated by a normal group velocity dispersion fiber of 1 m length using an optical parametric oscillator. The SC generations are accurately reproduced by analysis of a nonlinear Schrödinger equation including the optical Kerr effect and second-order dispersion. The compensation of the up-chirp of the SC pulses effectively compresses the pulsewidth to 60 fs in an anomalous group velocity dispersion fiber of 50 cm length. The ultrashort optical pulses generated by this technique will become a useful source for the characterization of materials and devices operating at fiber telecommunication wavelength.
Refractive Index, Density and Polarizability of Silica Glass with Various Fictive Temperatures
Authors: Kakiuchida Hiroshi , Saito Kazuya , Ikushima Akira J.
Published: February 2005

The refractive index and density of silica glass were measured for various fictive temperatures. They both increase without any local maxima, as the fictive temperature increases up to 1550°C. From the relationship between the refractive index and the density, polarizability was estimated using the Lorentz-Lorenz formula. The polarizability decreases with increasing density, while the refractive index increases. The variation in refractive index with fictive temperature depends on changes in not only the density but also the polarizability. The polarizability was found to contribute to the variation in refractive index to the extent of about one half of that from the density. With increasing density, the refractive index at a longer wavelength increases at a higher rate, which originates from a lower rate of decrease in polarizability at a longer wavelength.
Ultra-Low-Threshold Field Electron Emission from Pillar Array of Aligned Carbon Nanotube Bundles
Authors: Katayama Mitsuhiro , Lee Kuei-Yi , Honda Shin-ichi , Hirao Takashi , Oura Kenjiro
Published: February 2005

We observed the field electron emission of the technologically useful current density of 10 mA/cm2 at an extremely low threshold electric field (E
th) of 1.0 V/µm, from an array of pillars of aligned carbon nanotube bundles, which were grown on a Si substrate by thermal chemical vapor deposition. Adjusting the distance between the neighboring pillars (R) and the pillar height (H) to the optimal condition (R/H = 2) can effectually enhance the field concentration, resulting in a highly efficient electron emission. The obtained E
th is 1/2–1/3 times lower than the best values that have been reported to date.
Measurement of Magnetization Precession for NM/Ni80Fe20/NM (NM = Cu and Pt) Using Time-Resolved Kerr Effect
Authors: Nakamura Hiroaki , Ando Yasuo , Mizukami Shigemi , Kubota Hitoshi , Miyazaki Terunobu
Published: February 2005

Magnetization precession of NM/Ni80Fe20/NM (NM = Cu and Pt) multilayers was measured by the time-resolved magneto-optical Kerr effect (MOKE). A MOKE measurement system equipped with a pulse laser and optical delay lines was set up and samples were combined using a photoconductive switch for pulse field generation. Clear oscillation and relaxation of the magnetization of motion in time domain were successfully observed. Gilbert damping constant α for Cu/Ni80Fe20/Cu multilayers was independent of the thickness of Ni80Fe20. While α for Pt/Ni80Fe20/Pt multilayers was enhanced as Ni80Fe20 layer became thinner. These experimental data were well fitted by LLG calculation with the same α obtained by ferromagnetic resonance (FMR).
An Analysis of the Anomalous Dip in Scattering Parameter S11 of InGaP/GaAs Heterojunction Bipolar Transistors (HBTs)
Authors: Lin Yo-Sheng , Lu Shey-Shi
Published: February 2005

The anomalous dip in scattering parameter S
11 of InGaP/GaAs heterojunction bipolar transistors (HBTs) is explained quantitatively. Our results show that for InGaP/GaAs HBTs, the input impedance can be represented by a “shifted” series RC circuit at low frequencies and a “shifted” parallel RC circuit at high frequencies. The appearance of the anomalous dip of S
11 in a Smith chart is caused by this inherent ambivalent characteristic of the input impedance. It is found that under constant collector-emitter voltage (V
CE), an increase of base current (which corresponds to a decrease of base-emitter resistance and an increase of transconductance) enhances the anomalous dip. In addition, the anomalous dip in S
11 of InGaP/GaAs HBTs can also be interpreted in terms of poles and zeros.
Surface-modified Diamond Field-effect Transistors for Enzyme-immobilized Biosensors
Authors: Song Kwang-Soup , Degawa Munenori , Nakamura Yusuke , Kanazawa Hirofumi , Umezawa Hitoshi , Kawarada Hiroshi
Published: February 2005

The enzyme sensors using electrolyte-solution-gate diamond field effect transistors (SGFETs) have been developed for the first time. The hydrogen-terminated surface channel of the FETs was modified into partially aminated and oxygen-terminated (H-A-O-terminated) with irradiation of ultraviolet in an ammonia environment. The pH response of that is obtained about 50 mV/pH at pH 2–10. The concentration of substrates (urea or glucose) in the electrolyte solution has been detected by the pH change due to the bio-catalyzed effect of enzyme (urease or glucose oxidase), which is immobilized on the channel of SGFETs. The sensitivity of urea and glucose is approximately 30 mV/decade and 20 mV/decade respectively.
(Hg,Re)Ba2CaCu2Oy [100]-Tilt Grain Boundary Josephson Junctions with High Characteristic Voltages
Authors: Ogawa Akihiro , Sugano Tsuyoshi , Wakana Hironori , Kamitani Ai , Adachi Seiji , Tarutani Yoshinobu , Tanabe Keiichi
Published: February 2005

[100]-tilt grain boundary Josephson junctions have been fabricated using epitaxial (Hg0.9Re0.1)Ba2CaCu2O
y
((Hg,Re)-1212) films grown on SrTiO3 bicrystal substrates with thin buffer layers of 123 compounds. The junctions with the tilt angles of 30° and 36.8° exhibited resistively-shunted-junction-type current-voltage characteristics with very low excess current in a wide temperature range from 4.2 to 110 K. They also showed the characteristic voltages or the products of the critical current I
c and the normal resistance R
n of 1.0–1.4 mV and 0.2–0.4 mV at 77 K and 100 K, respectively, which are substantially higher than those for (Hg,Re)-1212 [001]-tilt junctions. Strong hysteresis in the magnetic field dependence of I
c curve was observed for the applied field larger than a certain threshold value, suggesting flux penetration between the CuO2 planes.
Universal Processing Technique for Protein Crystals Using Pulsed UV Laser
Authors: Murakami Atsutoshi , Kitano Hiroshi , Adachi Hiroaki , Matsumura Hiroyoshi , Takano Kazufumi , Inoue Tsuyoshi , Mori Yusuke , Doi Masaaki , Sasaki Takatomo
Published: February 2005

We demonstrated the laser processing of three types of soft protein crystals using a 193 nm deep-UV pulsed laser. In particular, high-solvent-content crystals, phosphoenolpyruvate carboxylase (PEPC) crystals, were successfully processed without causing significant damage. An unchanged resolution limit between pre- and post-processings in X-ray diffraction measurements showed that laser irradiation has little influence on crystallinity. These results reveal that the processing using a deep-UV laser is effective for various protein crystals and will be very useful in accelerating protein structural analysis.
Large Magnetoresistance in Magnetic Tunnel Junctions Using Co-Mn-Al Full Heusler Alloy
Authors: Kubota Hitoshi , Nakata Jun , Oogane Mikihiko , Ando Yasuo , Sakuma Akimasa , Miyazaki Terunobu
Published: February 2005

Magnetic tunnel junctions with a stacking structure of Cr/Co-Mn-Al/Al-O/Co-Fe/Ir-Mn were fabricated using a UHV magnetron-sputtering machine. Co-Mn-Al films showed B2 structure, which involves partial disorder between Mn and Al sites. Tunnel magnetoresistance ratios at room temperature were 27% and 40% before and after annealing at 250°C, respectively. Those values are much higher than the ones obtained in previous experiments using half Heusler alloys.
The FcγRIIa polymorphism R/H131, autoantibodies against the platelet receptors GPIbα and FcγRIIa and a risk for thromboembolism in lupus anticoagulant patients
Authors: Schallmoser Katharina , Rosin Christiane , Knittelfelder Regina , Sailer Thomas , Ulrich Silvia , Zoghlami Claudia , Lehr Stephan , Pabinger Ingrid , Panzer Simon
Published: February 2005

There is a clear propensity of individuals with lupus anticoagulant (LA) for thromboembolic disease (TE). Yet, it is not clear how individuals at risk for TE can be differentiated from those who are not. The FcγRIIa receptor is the only Fc receptor expressed by platelets. As platelets can be activated via this receptor, we have compared gene frequencies of the FcγRIIa polymorphism R/H131 in 46 and 27 patients with (LA/TE+) and without TE (LA/TE-), respectively, in an exploratory study. Furthermore, we investigated the presence of autoantibodies against FcγRIIa and/or GPIbα, which is in close proximity to the FcγRIIa and interacts with it functionally, and a possible linkage of antibody formation to HLA class II alleles. The FcγRIIa-R/R131 genotype was significantly less frequent in patients with LA compared to controls (p< 0.025). These findings were due to an increased frequency of heterozygous patients in the LA/TE+ cohort (odds ratio 6.76, 95% confidence interval 1.55 – 62.03, p< 0.008). For the first time, heterozygosity, rather than homozygosity, can be linked to disease, which may be explained by the dual function of the FcγRIIa, namely binding of antibodies to platelets and thereby their activation, and, on the other hand, clearance of antibody coated platelets by the phagocyte system. There was no correlation between the presence of anti-FcγRIIa or anti GPIbα autoantibodies and the FcγRIIa -R/H131 polymorphism, nor the incidence of TE, nor HLA class II alleles.
Medical conditions increasing the risk of chronic thromboembolic pulmonary hypertension
Authors: Bonderman Diana , Jakowitsch Johannes , Adlbrecht Christopher , Schemper Michael , Kyrle Paul , Schönauer Verena , Exner Markus , Klepetko Walter , Kneussl Meinhard , Maurer Gerald , Lang Irene
Published: February 2005

Chronic thromboembolic pulmonary hypertension (CTEPH) is characterized by organized thromboemboli that obstruct the pulmonary vascular bed. Although CTEPH is a serious complication of acute symptomatic pulmonary embolism in 4% of cases, signs, symptoms and classical risk factors for venous thromboembolism are lacking. The aim of the present study was to identify medical conditions conferring an increased risk of CTEPH. We performed a case-control-study comparing 109 consecutive CTEPH patients to 187 patients with acute pulmonary embolism that was confirmed by a high probability lung scan. Splenectomy (odds ratio=13, 95% CI 2.7–127), ventriculoatrial (VA-) shunt for the treatment of hydrocephalus (odds ratio=13, 95% CI 2.5–129) and chronic inflammatory disorders, such as osteomyelitis and inflammatory bowel disease (IBD, odds ratio=67, 95% CI 7.9–8832) were associated with an increased risk of CTEPH.
Do hormonal contraceptives stimulate growth of neurofibromas? A survey on 59 NF1 patients
Authors: Lammert Marge , Mautner Victor-Felix , Kluwe Lan
Published: February 2005

Background

Neurofibromas are benign tumors of the peripheral nerves and hallmark of neurofibromatosis type 1 (NF1), a tumor suppressor gene syndrome. Neurofibromas mostly start developing at puberty and can increase in size and number during pregnancy. Expression of progesterone receptors has been found in 75% of the tumors. Many female NF1 patients are thus concerned about the possibility that hormonal contraceptives may stimulate the growth of their neurofibromas.

Methods

A survey was carried out on 59 female NF1 patients who are practicing or have practiced hormonal contraception to examine the effect of the various contraceptives on the growth of neurofibromas.

Results

Majority (53 out of 58) of patients who received oral estrogen-progestogen or pure progestogen preparations reported no associated tumor growth. In contrast, significant tumor growth was reported by two patients who received depot contraceptive containing high dose of synthetic progesterone.

Conclusions

Oral contraceptives do not seem to stimulate the growth of neurofibromas in NF1 patients. High doses of progesterone might stimulate the growth of neurofibromas and deserve more caution.
Functional complementation of RNA interference mutants in trypanosomes
Authors: Rusconi Filippo , Durand-Dubief Mickaël , Bastin Philippe
Published: February 2005

Background

In many eukaryotic cells, double-stranded RNA (dsRNA) triggers RNA interference (RNAi), the specific degradation of RNA of homologous sequence. RNAi is now a major tool for reverse-genetics projects, including large-scale high-throughput screens. Recent reports have questioned the specificity of RNAi, raising problems in interpretation of RNAi-based experiments.

Results

Using the protozoan Trypanosoma brucei as a model, we designed a functional complementation assay to ascertain that phenotypic effect(s) observed upon RNAi were due to specific silencing of the targeted gene. This was applied to a cytoskeletal gene encoding the paraflagellar rod protein 2 (TbPFR2), whose product is essential for flagellar motility. We demonstrate the complementation of TbPFR2, silenced via dsRNA targeting its UTRs, through the expression of a tagged RNAi-resistant TbPFR2 encoding a protein that could be immunolocalized in the flagellum. Next, we performed a functional complementation of TbPFR2, silenced via dsRNA targeting its coding sequence, through heterologous expression of the TbPFR2 orthologue gene from Trypanosoma cruzi: the flagellum regained its motility.

Conclusions

This work shows that functional complementation experiments can be readily performed in order to ascertain that phenotypic effects observed upon RNAi experiments are indeed due to the specific silencing of the targetted gene. Further, the results described here are of particular interest when reverse genetics studies cannot be easily achieved in organisms not amenable to RNAi. In addition, our strategy should constitute a firm basis to elaborate functional-dissection studies of genes from other organisms.
Omega-3 fatty acids decreased irritability of patients with bipolar disorder in an add-on, open label study
Authors: Sagduyu Kemal , Dokucu Mehmet E , Eddy Bruce A , Craigen Gerald , Baldassano Claudia F , Yıldız Ayşegül
Published: February 2005

This is a report on a 37-patient continuation study of the open ended, Omega-3 Fatty Acid (O-3FA) add-on study. Subjects consisted of the original 19 patients, along with 18 new patients recruited and followed in the same fashion as the first nineteen. Subjects carried a DSM-IV-TR diagnosis of Bipolar Disorder and were visiting a Mood Disorder Clinic regularly through the length of the study. At each visit, patients' clinical status was monitored using the Clinical Monitoring Form. Subjects reported on the frequency and severity of irritability experienced during the preceding ten days; frequency was measured by way of percentage of days in which subjects experienced irritability, while severity of that irritability was rated on a Likert scale of 1 – 4 (if present). The irritability component of Young Mania Rating Scale (YMRS) was also recorded quarterly on 13 of the 39 patients consistently. Patients had persistent irritability despite their ongoing pharmacologic and psychotherapy.

Omega-3 Fatty Acid intake helped with the irritability component of patients suffering from bipolar disorder with a significant presenting sign of irritability. Low dose (1 to 2 grams per day), add-on O-3FA may also help with the irritability component of different clinical conditions, such as schizophrenia, borderline personality disorder and other psychiatric conditions with a common presenting sign of irritability.
Correlation of sperm penetration assay score with polyspermy rate in in-vitro fertilization
Authors: Aoki Vincent W , Peterson C Matthew , Parker-Jones Kirtly , Hatasaka Harry H , Gibson Mark , Huang Ivan , Carrell Douglas T
Published: February 2005

Background

The sperm penetration assay (SPA) is used to predict the fertilizing capacity of sperm. Thus, some programs rely on SPA scores to formulate insemination plans in conjunction with in-vitro fertilization (IVF) cycles. The purpose of this study was to evaluate if a relationship exists between SPA scores and polyspermy rates during conventional IVF cycles.

Methods

A total of 1350 consecutive IVF patients using conventional IVF insemination were evaluated in the study. Oocytes were inseminated three hours post-retrieval by the addition of 150,000 to 300,000 progressively motile sperm. Approximately 18 hours after insemination, the oocytes were evaluated for fertilization by the visualization of pronuclei. The presence of three or more pronuclei was indicative of polyspermy. Polyspermy rates, fertilization success, embryo quality, and pregnancy rates were analyzed retrospectively to evaluate their relationship with SPA score, count, motility, number of progressively motile sperm inseminated, oocyte pre-insemination incubation time, patient age, and diagnosis.

Results

A significant positive relationship was observed between SPA score and polyspermy rate (rs = 0.10, p < 0.05). Patients with a normal SPA score had significantly higher polyspermy rates than those with abnormal SPA scores (6.3% ± 1.5% vs. 2.0% ± 0.7%, p < 0.05). Fertilization percentage was significantly lower in the group with severely abnormal SPA scores versus all other SPA groups (57.5% ± 2.1% vs. 70.2% ± 1.3%, p < 0.005). Although embryo quality was not affected, both clinical pregnancy and implantation rates improved slightly as SPA score increased. In addition, there was a decrease in the rate of spontaneous abortion as SPA score increased.

Conclusions

These data indicate SPA score is positively correlated with polyspermy rates and IVF fertilization percentage. Additionally, there is a slight increase in clinical pregnancy rates, and embryo implantation rates with increased SPA. Furthermore, there is a slight decrease in spontaneous abortions rates related to increased SPA.
Strain Measurement of Geogrids Using a Video-Extensometer Technique
Authors: Shinoda M , Bathurst RJ
Published: February 2005

The paper describes a novel technique to record displacements and compute local strains at the surface of typical geogrid soil reinforcement products using a noncontact high resolution digital CCD camera (video-extensometer) technique. Specimens of biaxial polypropylene (PP) geogrid, knitted polyester (PET) geogrid, and uniaxial high-density polyethylene (HDPE) geogrid were subjected to in-isolation wide-width strip tensile loading under constant rate of strain (CRS), constant load (creep), and stress relaxation load paths. The specimens were gripped using a set of split roller clamps. Targets painted on the surface of the specimens were tracked in both vertical and horizontal directions using a commercially available CCD camera with ancillary hardware and software. The paper examines repeatability of the test methodology and demonstrates the ability of the method to record strains at high resolution up to rupture and to identify nonuniform distribution of axial and lateral strains in geogrid specimens.
A probabilistic model for Latent Semantic Indexing
Authors: Ding Chris H.Q.
Published: February 2005

Latent Semantic Indexing (LSI), when applied to semantic space built on text collections, improves information retrieval, information filtering, and word sense disambiguation. A new dual probability model based on the similarity concepts is introduced to provide deeper understanding of LSI. Semantic associations can be quantitatively characterized by their statistical significance, the likelihood. Semantic dimensions containing redundant and noisy information can be separated out and should be ignored because their negative contribution to the overall statistical significance. LSI is the optimal solution of the model. The peak in the likelihood curve indicates the existence of an intrinsic semantic dimension. The importance of LSI dimensions follows the Zipf‐distribution, indicating that LSI dimensions represent latent concepts. Document frequency of words follows the Zipf distribution, and the number of distinct words follows log‐normal distribution. Experiments on five standard document collections confirm and illustrate the analysis.
Sterically Hindered Carbonyl O‐Oxides and Dioxiranes − (6‐tert‐Butyl‐2,3,4‐trimethylphenyl)phenylcarbonyl O‐Oxide and (6‐tert‐Butyl‐2,3,4‐trimethylphenyl)phenyldioxirane
Authors: Schroeder Kerstin , Sander Wolfram
Published: February 2005

(6‐tert‐Butyl‐2,3,4‐trimethylphenyl)phenylcarbonyl O‐oxide (1b) was generated by photooxidation of diazo compound 6b in an organic glass and in solution and characterized by UV/Vis spectroscopy and by its photo‐ and thermochemistry. With 4.5 min at 230 K the half‐life of 1b is considerably smaller than that of dimesityl ketone O‐oxide (1a). The only clearly detected thermal product of 1b is the corresponding ketone 3b. The isomeric (6‐tert‐butyl‐2,3,4‐trimethylphenyl)phenyldioxirane (2b) could also be synthesized and characterized by NMR spectroscopy. With a half‐life time of 20 min at 20 °C this dioxirane rearranges to the isochroman derivative 11 as the only product. Plausible mechanisms for this rearrangement, which involves the hydroxylation of a non‐activated C−H bond, are discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Recent Developments in Catalytic, Asymmetric α‐Halogenation: A New Frontier in Asymmetric Catalysis
Authors: France Stefan , Weatherwax Anthony , Lectka Thomas
Published: February 2005

The development of milder and more sophisticated halogenating reagents that offer significantly greater chemoselectivity and stereocontrol than diatomic halides has been critical to the realization of asymmetric α‐halogenation. Within the past few years several groups have reported catalytic, enantioselective methods for α‐halogenation achieved by utilizing the catalytic generation of either enolates (zwitterionic or metal‐based charge delocalized) or enamines. Most importantly, this recent work has greatly enhanced the synthetic utility of organic halogenations and, in doing so, opened up a promising new frontier in organic synthesis. This microreview presents recent advances in the area of catalytic, asymmetric α‐halogenations of carbonyl compounds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Efficient Synthesis of Functionalised 4‐Hydroxycyclopent‐2‐en‐1‐ones by Cyclisation of 1,3‐Bis(silyl) Enol Ethers and 1,3‐Dicarbonyl Dianions with 1,2‐Diketones
Authors: Holtz Edith , Köhler Valentin , Appel Bettina , Langer Peter
Published: February 2005

The cyclisation of 1,3‐bis(silyl) enol ethers and 1,3‐dicarbonyl dianions with 1,2‐diketones provides convenient access to functionalised 4‐hydroxycyclopent‐2‐en‐1‐ones. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Carbonyl Ylide Cycloadditions to C,C‐Double Bonds of Methylenecyclopropanes
Authors: Molchanov Alexander P. , Diev Vyacheslav V. , Magull Jörg , Vidović Denis , Kozhushkov Sergei I. , de Meijere Armin , Kostikov Rafael R.
Published: February 2005

The carbonyl ylide 1,3‐dipoles generated by dirhodium tetraacetate‐catalyzed decomposition from 1‐diazo‐5‐phenylpentane‐2,5‐dione (4) and 1‐(1‐acetylcyclopropyl)‐2‐diazo‐ethanone (5) cycloadd to substituted methylenecyclopropanes2a–e and bicyclopropylidene (3) to give substituted mono‐, di‐, and trispirocyclopropanated 8‐oxabicyclo[3.2.1]octan‐2‐ones 7, 8, and 11 and 7‐oxabicyclo[2.2.1]heptan‐2‐ones 10 and 12 in 6–75 % yields with different regio‐ and stereoselectivities. The structures of the two isomeric cycloadducts endo‐ and exo‐10d formed from the carbonyl ylide derived from 5 and methyl 2‐chloro‐2‐(cyclopropylidene)acetate (2d) were confirmed by X‐ray crystal structure analyses. (Diphenylmethylene)cyclopropane and trans‐3‐methylenecyclopropane‐1,2‐dicarboxylate (diethyl ester of Feist’s acid) did not undergo such cycloadditions, while methylenecyclobutane (13) afforded a mixture of [3+2] and [2+1] cycloadducts 14 and 15 in 28 and 29 % yields, respectively. The scope and limitations of these cycloadditions as well as the influence of different factors upon their regio‐ and stereoselectivities are discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
LAF‐4 is aberrantly expressed in human breast cancer
Authors: To Minh D. , Faseruk Stephanie A. , Gokgoz Nalan , Pinnaduwage Dushanthi , Done Susan J. , Andrulis Irene L.
Published: February 2005

LAF‐4, which encodes a nuclear protein with transactivation potential, is fused to the MLL gene in acute lymphoblastic leukemia (ALL). We identified LAF‐4 as a gene that is transcriptionally deregulated in breast tumors and thus may have a pathological role in mammary tumorigenesis. In line with the previous finding that LAF‐4 expression is tissue specific, we did not detect any LAF‐4 mRNA in normal mammary epithelial cell lines. However, 2 of 5 breast cancer cell lines were found to express LAF‐4 at both the RNA and protein levels. In 2 of 9 primary tumor‐normal pairs, the expression of LAF‐4 was clearly elevated in the tumor tissue. Using RNA in situ hybridization, we demonstrated that LAF‐4 is expressed in mammary tumor cells but not in normal acini. In a group of 64 primary human breast tumors, we found that LAF‐4 was overexpressed in approximately 20% of the cases. Although epigenetic changes may be involved in altered expression of some genes, differences in LAF‐4 expression were not associated with DNA methylation of the predicted promoter region. Our results suggest that LAF‐4 may be a proto‐oncogene that is transcriptionally activated in some cases of breast cancer. © 2005 Wiley‐Liss, Inc.
Top‐down identification of endogenous peptides up to 9 kDa in cerebrospinal fluid and brain tissue by nanoelectrospray quadrupole time‐of‐flight tandem mass spectrometry
Authors: Möhring Thomas , Kellmann Markus , Jürgens Michael , Schrader Michael
Published: February 2005

Recent work on protein and peptide biomarker patterns revealed the difficulties in identifying their molecular components, which is indispensable for validation of the biological context. Cerebrospinal fluid and brain tissue are used as sources to discover new biomarkers, e.g. for neurodegenerative diseases. Many of these biomarker candidates are peptides with a molecular mass of <10 kDa. Their identification is favourably achieved with a ‘top‐down’ approach, because this requires less purification and an enzymatic cleavage will often not yield enough specific fragments for successful database searches. Here, we describe an approach using quadrupole time‐of‐flight mass spectrometry (TOFMS) as a highly efficient mass spectrometric purification and identification tool after off‐line decomplexation of biological samples by liquid chromatography. After initial peptidomic screening with matrix‐assisted laser desorption/ionization (MALDI) TOFMS, the elution behaviour in chromatography and the exact molecular mass were used to locate the same signals in nanoelectrospray measurements. Most of the peaks detected in MALDI‐TOFMS could be retrieved in nanoelectrospray quadrupole TOFMS. Suitable collision energies for informative fragment spectra were investigated for different parent ions, charge states and molecular masses. After collision‐induced dissociation, the resulting fragmentation data of multiply charged ions can become much more complicated than those derived from tryptic peptide digests. However, the mass accuracy and resolution of quadrupole TOF instruments results in high‐quality data suitable for determining peptide sequences. The protein precursor, proteolytic processing and post‐translational modifications were identified by automated database searches. This is demonstrated by the exemplary identifications of thymosin beta‐4 (5.0 kDa) and NPY (4.3 kDa) from rat hypothalamic tissue and ubiquitin (8.6 kDa) from human cerebrospinal fluid. The high data quality should also allow for de novo identification. This methodology is generally applicable for peptides up to a molecular mass of about 10 kDa from body fluids, tissues or other biological sources. Copyright © 2005 John Wiley & Sons, Ltd.
Peptidomic analysis of the larval Drosophila melanogaster central nervous system by two‐dimensional capillary liquid chromatography quadrupole time‐of‐flight mass spectrometry
Authors: Baggerman Geert , Boonen Kurt , Verleyen Peter , De Loof Arnold , Schoofs Liliane
Published: February 2005

Peptides are the largest class of signalling molecules found in animals. Nevertheless, in most proteomic studies peptides are overlooked since they literally fall through the mazes of the net. In analogy with proteomics technology, where all proteins expressed in a cell or tissue are analyzed, the peptidomic approach aims at the simultaneous visualization and identification of the whole peptidome of a cell or tissue, i.e. all expressed peptides with their post‐translational modifications. In this paper we describe the analysis of the larval fruit fly central nervous system using two‐dimensional capillary liquid chromatography/quadrupole time‐of‐flight tandem mass spectrometry (LC/Q‐TOF‐MS/MS. Using the central nervous systems of only 50 larval Drosophila as starting material, we identified 38 peptides in a single analysis, 20 of which were not detected in a previous study that reported on the one‐dimensional capillary LC/MS/MS analysis of the same tissue. Among the 38 sequenced peptides, some originate from precursors, such as the tachykinin and the IFamide precursor that were entirely missed in the first study. This clearly demonstrates that the two‐dimensional capillary LC approach enhances the coverage of the peptidomic analysis. Copyright © 2005 John Wiley & Sons, Ltd.
Analysis of elliptical waveguides by the method of fundamental solutions
Authors: Young D. L. , Hu S. P. , Chen C. W. , Fan C. M. , Murugesan K.
Published: February 2005

The present work describes the application of the method of fundamental solutions (MFS) for the solution of cutoff wavelengths of elliptical waveguides. Since the MFS employs a formulation using boundary values only, the cutoff wavelengths are determined by applying the singular value decomposition (SVD) technique. The use of the MFS to solve the governing (Helmholtz) equation guarantees a solution without singularities, since it does not use discretized points to determine the solution at the interior of the computational domain. The combination of the MFS and SVD techniques has resulted in a simpler and efficient numerical solution procedure, as compared to other schemes. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 44: 552–558, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20695
The PMD effect in OSNR monitoring
Authors: Sun F. G. , Lu Z. G. , Xiao G. Z. , Grover C. P.
Published: February 2005

Polarization‐mode dispersion (PMD) effect on monitoring optical signal‐to‐noise ratio (OSNR) by polarization‐nulling technique has been investigated. Without PMD, the maximum and minimum optical power is measured using the polarization‐nulling method to provide accurate OSNR. Due to the difference in arrival time for the two component pulses, it is impossible to transfer the pulse to a linear polarization state. The output power after the polarizer will depend on both OSNR and differential group delay (DGD). It is shown that the accuracy of the polarization‐nulling method can be reduced significantly by PMD. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 44: 558–560, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20696
Molecular diagnosis of inheritable neuromuscular disorders. Part II: Application of genetic testing in neuromuscular disease
Authors: Greenberg Steven A. , Walsh Ronan J.
Published: February 2005

Molecular genetic advances have led to refinements in the classification of inherited neuromuscular disease, and to methods of molecular testing useful for diagnosis and management of selected patients. Testing should be performed as targeted studies, sometimes sequentially, but not as wasteful panels of multiple genetic tests performed simultaneously. Accurate diagnosis through molecular testing is available for the vast majority of patients with inherited neuropathies, resulting from mutations in three genes (PMP22, MPZ, and GJB1); the most common types of muscular dystrophies (Duchenne and Becker, facioscapulohumeral, and myotonic dystrophies); the inherited motor neuron disorders (spinal muscular atrophy, Kennedy's disease, and SOD1 related amyotrophic lateral sclerosis); and many other neuromuscular disorders. The role of potential multiple genetic influences on the development of acquired neuromuscular diseases is an increasingly active area of research. Muscle Nerve, 2005
Effects of repeated water exchange on the swelling behavior of poly(sodium acrylate) gels crosslinked by aluminum ions
Authors: Sato H. , Hirashima Y. , Suzuki A. , Goto M. , Tokita M.
Published: February 2005

Polyelectrolyte hydrogels, physically crosslinked by metal ions, were synthesized using poly(sodium acrylate) as the main constituent and Al ions as the crosslinker. The swelling ratio of the gel was measured whenever the solvent water was repeatedly exchanged in a constant interval. The as‐synthesized gel exhibited two relaxation processes; the gel swelled at the first stage, then shrunk very slowly at the second stage, and recovered to the initial size just after the gelation (ultimately, the gel became smaller than that). The relaxation times of both processes were found longer (exceptionally longer for the shrinking process) than the conventional collective diffusion of polymer networks. The diffused amounts of Al ions and Na counter ions in the solvent were also measured at each water exchange. The diffusion of Al ions into the solvent was found to finish when the swelling ratio took the maximum (at the end of the first stage), while Na ions continued to diffuse until the diameter became the final one (at the end of the second stage). The microscopic structural changes by the repeated water exchange were obtained by the measurements of ATR FT‐IR spectroscopy on the gels with different swelling ratios. The carboxyl groups were gradually protonated on both stages, and the formation of hydrogen bonding was accelerated on the second stage. Effects of the repeated water exchange on the swelling behavior are discussed in terms of the diffusion of Al ions into the solvent, the exchange of Na counter ions by protons, and the formation of hydrogen bonding. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 753–763, 2005
QUANTUM GROUPOIDS OF COMPACT TYPE
Authors: Enock Michel
Published: February 2005

To any groupoid, equipped with a Haar system, Jean-Michel Vallin had associated several objects (pseudo-multiplicative unitary, Hopf-bimodule) in order to generalize, up to the groupoid case, the classical notions of multiplicative unitary and Hopf–von Neumann algebra, which were intensely used to construct quantum groups in the operator algebra setting. In two former articles (one in collaboration with Jean-Michel Vallin), starting from a depth-2 inclusion of von Neumann algebras, we have constructed such objects, which allowed us to study two ‘quantum groupoids’ dual to each other. We are now investigating in greater details the notion of pseudo-multiplicative unitary, following the general strategy developed by Baaj and Skandalis for multiplicative unitaries.

AMS 2000 Mathematics subject classification: Primary 46L89; 22A22; 81R50
DOUBLE CROSSED PRODUCTS OF LOCALLY COMPACT QUANTUM GROUPS
Authors: Baaj Saad , Vaes Stefaan
Published: February 2005

For a matched pair of locally compact quantum groups, we construct the double crossed product as a locally compact quantum group. This construction generalizes Drinfeld’s quantum double construction. We study the modular theory and the $\mathrm{C}^*$-algebraic properties of these double crossed products, as well as several links between double crossed products and bicrossed products. In an appendix, we study the Radon–Nikodym derivative of a weight under a quantum group action (following Yamanouchi) and obtain, as a corollary, a new characterization of closed quantum subgroups.

AMS 2000 Mathematics subject classification: Primary 46L89. Secondary 46L65
Optional water development strategies for the Yellow River Basin: Balancing agricultural and ecological water demands
Authors: Cai Ximing , Rosegrant Mark W.
Published: February 2005

The Yellow River Basin is of the utmost importance for China in terms of food production, natural resources management, and socioeconomic development. Water withdrawals for agriculture, industry, and households in the past decade have seriously depleted environmental and ecological water requirements in the basin. This study presents a modeling scenario analysis of some water development strategies to harmonize water withdrawal demand and ecological water demand in the Yellow River Basin through water savings and interbasin water transfers. A global water and food analysis model including the Yellow River Basin as one of the modeling units is applied for the analysis. The model demonstrates that there is little hope of resolving the conflict between agriculture water demand and ecological water demand in the basin if the current water use practices continue. Trade‐offs exist between irrigation water use and ecological water use, and these trade‐offs will become more intense in future years with population growth, urbanization, and industrial development as well as growing food demand. Scenario analysis in this study concludes that increasing basin water use efficiency to 0.67 first and then supplementary water availability by interbasin water transfer through the South‐North Water Transfer Project may provide a solution to water management of the Yellow River Basin in the next 25 years.
Relative contribution of electrons to the stormtime total ring current energy content
Authors: Liu S. , Chen M. W. , Roeder J. L. , Lyons L. R. , Schulz M.
Published: February 2005

We evaluate the relative importance of stormtime ring current electrons to protons by calculating the energy content ratio of electrons to protons for typical ring current energies inferred from observations and simulations. We analyze Explorer 45 measurements taken around the minimum Dst(=−171 nT) of the 17 December 1971 storm. We simulate the electron and proton ring current energy content during a hypothetical storm using drift‐loss simulations. From the data analysis, we find that electrons with energies of ∼1–50 keV and protons with energies of ∼10–200 keV contribute the most to the corresponding particle energy content. From both observations and simulations, the ring current electrons contribute only ∼1% as much energy content as ring current protons during quiet times. However, this ratio increases to ∼8–19% during storm main phase. Thus, the ring current electrons can contribute significantly to the ring current energy content during storms.
Aftershocks resulting from creeping sections in a heterogeneous fault
Authors: Zöller G. , Hainzl S. , Holschneider M. , Ben‐Zion Y.
Published: February 2005

We show that realistic aftershock sequences with space‐time characteristics compatible with observations are generated by a model consisting of brittle fault segments separated by creeping zones. The dynamics of the brittle regions is governed by static/kinetic friction, 3D elastic stress transfer and small creep deformation. The creeping parts are characterized by high ongoing creep velocities. These regions store stress during earthquake failures and then release it in the interseismic periods. The resulting postseismic deformation leads to aftershock sequences following the modified Omori law. The ratio of creep coefficients in the brittle and creeping sections determines the duration of the postseismic transients and the exponent p of the modified Omori law.