bluuebunny/crossref_metadata_2025 huggingface dataset:
Total Synthesis without Protection: Three‐Step Synthesis of Optically Active Clavicipitic Acids by a Biomimetic Route
Authors: Yokoyama Yuusaku , Hikawa Hidemasa , Mitsuhashi Masaharu , Uyama Aki , Hiroki Yasuhiro , Murakami Yasuoki
Published: March 2004

A three‐step synthesis of a mixture of optically active cis‐ and trans‐clavicipitic acids 6, which are ergot alkaloids, was achieved, starting from 4‐bromoindole (7) and dl‐serine (dl‐2). This short synthesis was made possible by omitting the protection and deprotection steps from the synthetic route. The key step was the spontaneous cyclization of 4‐vinyltryptophan (10) formed from the Heck reaction of 4‐bromotryptophan (8) with 2‐methyl‐3‐buten‐2‐ol (9) in aqueous media. During this investigation, we also found that the palladium‐catalyzed reaction of 8 with 9 showed an interesting pH dependence; under strongly basic conditions, the Heck reaction occurred to give a C4‐vinylated product 10, whereas an N‐allylated product 19b was formed under neutral or weakly basic conditions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Synthesis of Xyloketals, Natural Products from the Mangrove Fungus Xylaria sp
Authors: Krohn Karsten , Riaz Muhammad , Flörke Ulrich
Published: March 2004

The xyloketal family of compounds was synthesized by condensation of phloroglucinol (7) or 2,4‐dihydroxyacetophenone (15) with the enone 8a or 14 in multistep, one‐pot, domino reactions, leading to the xyloketals and 5‐demethylxyloketals, respectively. In the case of condensation with phloroglucinol (7), the mono‐, bis, and tris adducts 6/18, 2/19, 1/20 are formed; their ratios depend on the ratio of stating materials and reaction time. The ring junction of the pyran and furan rings B and C (at C‐2 and C‐6) is always cis. The cis orientation of the methyl groups at C‐2 and C‐5 is also predominant (8.5:1.5), as found in the natural products. In the bis and tris adducts (2/19, 1/20), the relative orientation of the rings B and C can be syn and anti, with the sterically less demanding anti orientation slightly favored statistically. Xyloketal D (4a) was obtained in the condensation of 15 with enantiomerically enriched enone 8a, confirming the absolute configuration of the natural product. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
3‐Tocopherylisoxazolines by [2+3] Cycloaddition
Authors: Rosenau Thomas , Adelwöhrer Christian , Hofinger Andreas , Mereiter Kurt , Kosma Paul
Published: March 2004

New isoxazoline derivatives of α‐tocopherol (1), the main component of vitamin E, were synthesized in a facile, two‐step sequence consisting of nitration followed by 1,3‐dipolar cycloaddition. 5‐Nitromethyl‐γ‐tocopheryl acetate (3), obtained from the cheap α‐tocopheryl acetate (2) by direct nitration in one step, acted as the nitrile oxide precursor in the reaction with various alkenes. The facile conversion proceeded in the presence of equimolar amounts of PhNCO and catalytic amounts of triethylamine. The NMR spectra of the product isoxazolines 5−13, showing strongly temperature‐dependent resonances of the 4′′‐CH, 4‐CH2 and the acetyl group, are discussed, and the crystal structures of model compounds containing a methyl group instead of the isoprenoid side chain are presented. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Synthesis of a 3,4‐Di‐O‐substituted Heptose Structure: A Partial Oligosaccharide Expressed in Neisserial Lipooligosaccharide
Authors: Kubo Hiroyuki , Ishii Kazuyuki , Koshino Hiroyuki , Toubetto Kenji , Naruchi Kentarou , Yamasaki Ryohei
Published: March 2004

We have synthesized a tetrasaccharide containing a 3,4‐dibranched L‐glycero‐D‐manno‐heptose (Hep), β‐lactosyl‐(1⇄4)‐[L‐α‐D‐Hep‐(1⇄3)]‐L‐α‐D‐Hep 19, by using a mannose (Man) derivative as an acceptor. Prior to the construction of the branched Hep, we confirmed that the 3,4‐dibranched Man structure could be synthesized using a 3‐branched Man 6 as an acceptor. Glycosylation of the acceptor 6 using hepta‐O‐acetyl‐α‐lactosyl trichloroacetimidate (7) gave the desired 3,4‐dibranched structure, β‐lactosyl‐(1⇄4)‐[α‐Man‐(1⇄3)]‐α‐Man 8. As expected, β‐lactosyl‐(1⇄4)‐[L‐α‐D‐Hep‐(1⇄3)]‐α‐D‐Man 14 was also obtained by glycosylating the 4‐OH acceptor 13 with 7 in a similar manner. The Man residue of 14 was converted into the Hep unit by Swern oxidation, Grignard reaction, and oxidative cleavage followed by reduction. Thus, we constructed the 3,4‐dibranched Hep structure 19 by using the 3‐branched Man 13 as an acceptor. The current results demonstrate that the gauche orientation of the O‐3 and O‐4 units of the Man configuration does not prevent the formation of the 3,4‐di‐O‐substituted structure. This approach should provide an alternative method to synthesize the 3,4‐dibranched Hep structure expressed in LOS produced by pathogenic Gram‐negative bacteria such as the Neisserial and Haemophilus species. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Synthesis of New Constrained Tricyclic Amines and Tricyclic Aminophosphonates Containing the 2‐Azatricyclo[3.3.0.03,6]octane Skeleton
Authors: Rammeloo Thomas , Stevens Christian V. , Soenen Bram
Published: March 2004

A short and easy method for the preparation of the 2‐azatricyclo[3.3.0.03,6]octane skeleton is described. The key step consists of an intramolecular ring closure of an endo‐oriented amino group and an exo‐oriented bromine atom. The amines were prepared through reduction of a suitable bicyclic imine. Nucleophilic addition of phosphite to the imines gave the corresponding aminophosphonates, which could be ring‐closed to the tricyclic aminophosphonates through an analogous pathway. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Iron‐Catalyzed Transformations of 2‐Chloro‐1,6‐heptadienes
Authors: Nečas David , Kotora Martin , Císařová Ivana
Published: March 2004

(Phosphane)iron complexes in the presence of excess trialkylaluminium reagents catalyze various transformations of 2‐chloro‐α,ψ‐dienes, depending on their structure. Most notably, in the cases of simple 2‐chloro‐1,6‐heptadienes, cyclization with transfer of the alkyl group (Me and Et) from the corresponding trialkylaluminium compound was observed to give 2‐alkyl‐1‐methylidenecyclopentanes. Reaction with 2‐chloro‐1,7‐octadiene afforded the product of reductive dehalogenation. In the case of 2‐chloro‐4‐aza‐1,6‐heptadiene a partial or complete hydrogenation of the double bonds was observed depending on the amount of trialkylaluminum reagent used. Interestingly, allyl(2‐chloroallyl)malonate underwent C−C bond cleavage with the loss of an allyl group to give (2‐chloroallyl)malonate. In the presence of ruthenium catalysts only reductive dehalogenation was observed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
The Structures of the Lipid A Moieties from the Lipopolysaccharides of Two Phytopathogenic Bacteria, Xanthomonas campestris pv. pruni and Xanthomonas fragariae
Authors: Silipo Alba , Molinaro Antonio , Lanzetta Rosa , Parrilli Michelangelo , Lindner Buko , Holst Otto
Published: March 2004

Lipopolysaccharides (LPSs) are vital and exclusive structural components of the outer membranes of all Gram‐negative bacteria. They play an important role in the communication between the pathogen and both animal and vegetal host cells. Structurally, they comprise in their smooth (S) form three regions, namely the O‐specific polysaccharide (or O‐antigen), the core region and the lipid A (the endotoxic active moiety). In this paper, the structure of the lipid A moieties from two lipopolysaccharides of two phytopathogenic bacteria, X. campestris pv. pruni and Xanthomonas fragariae, is described. The sugar backbone is constituted by the typical bis(phosphorylated)β‐(1′⇄6)‐linked D‐glucosamine disaccharide. Both lipid A fractions are remarkably heterogeneous with respect to the fatty acid chain length. The major species are hexacylated lipid A, with a symmetric [3+3] distribution in which the secondary fatty acids are exclusively ester‐linked. The primary structure of these two complex glycolipids is herein elucidated by means of chemical degradation, MS spectrometry and 2D NMR spectroscopy. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Cover Picture: Oxidative Fragmentation of the Bridged β‐Triketone Core of Hyperforin (Eur. J. Org. Chem. 6/2004)
Authors: Verotta Luisella , Lovaglio Erminio , Sterner Olov , Appendino Giovanni , Bombardelli Ezio
Published: March 2004

The cover picture shows Hypericum perforatum in full bloom, its bioactive compound hyperforin and the unusual structure of two oxidized products, whose mechanism of formation is discussed in the article by L. Verotta, O. Sterner et al. on p. 1193 ff.
Ease of imagination moderates reactions to differently framed health messages
Authors: Broemer Philip
Published: March 2004

Three studies test the hypothesis that the subjective ease of symptom imagination moderates the impact of differently framed messages on attitudes toward performing health behaviours. By drawing on the simulation heuristic, it is argued that the vividness of information is reflected in the subjective ease with which people can imagine having symptoms of an illness. This state of mind can be more or less congruent with the theme of a message, accentuating certain health‐related outcomes more than others. The results show that negatively framed messages are more persuasive when symptom imagination is relatively easy and that positively framed messages are more effective when symptom imagination is relatively difficult. Consistent with a dual‐process view, Study 3 showed a stronger impact of ease of imagination when relevance was low rather than high. Copyright © 2004 John Wiley & Sons, Ltd.
A study on dynamic and thermodynamic aspects of breaks in the summer monsoon over India
Authors: Bhatla R. , Mohanty U. C. , Raju P. V. S. , Madan O. P.
Published: March 2004

The rainfall associated with the Indian summer monsoon shows large intraseasonal and interannual variability. Break‐monsoon conditions are one of the important epochs of the monsoon, and they contribute significantly to the intraseasonal variability of the monsoon. The National Centers for Environmental Prediction–National Center for Atmospheric Research reanalysis data sets are used to investigate the significant energy budget terms during the pre‐break (5 days prior to the commencement of the break), break and post‐break (5 days after the cessation of the break) periods. In the present study, certain dynamic and thermodynamic characteristics of the monsoon circulation during break‐monsoon conditions are investigated. The important terms in the various energy budget equations are analysed between the surface and 100 hPa for the break and its departures from pre‐ and post‐break for the period 1968–96. The statistical significance of these departures is also examined by Student's t‐test at the 95% confidence level. The volume integral of the budget terms is also examined in four sectors, i.e. the Arabian Sea, Bay of Bengal, northern India and central India.

Significant changes in the wind field and vorticity at 850 hPa take place in the monsoon trough zone, coastal regions of the western coast of India and the southwestern Bay of Bengal off the southern Indian coast. The vertically upward rising arm of the Hadley cell weakens during the break phase. The strong flux convergence of kinetic energy in the central Arabian Sea and flux divergence in the northeastern Bay of Bengal weakens during pre‐ and post‐break periods. Significant changes in the diabatic heating horizontal flux of heat and moisture are observed in the monsoon trough zone, central and northwestern Bay of Bengal. The Bay of Bengal and central India sectors show higher magnitudes and changes in respect of dynamic and thermodynamic parameters compared with the Arabian Sea and northern India. Copyright © 2004 Royal Meteorological Society
Modern glacier retreat on Kilimanjaro as evidence of climate change: observations and facts
Authors: Kaser Georg , Hardy Douglas R. , Mölg Thomas , Bradley Raymond S. , Hyera Tharsis M.
Published: March 2004

In recent years, Kilimanjaro and its vanishing glaciers have become an ‘icon’ of global warming, attracting broad interest. In this paper, a synopsis of (a) field observations made by the authors and (b) climatic data as reported in the literature (proxy and long‐term instrumental data) is presented to develop a new concept for investigating the retreat of Kilimanjaro's glaciers, based on the physical understanding of glacier–climate interactions. The concept considers the peculiarities of the mountain and implies that climatological processes other than air temperature control the ice recession in a direct manner. A drastic drop in atmospheric moisture at the end of the 19th century and the ensuing drier climatic conditions are likely forcing glacier retreat on Kilimanjaro. Future investigations using the concept as a governing hypothesis will require research at different climatological scales. Copyright © 2004 Royal Meteorological Society
Changes of air temperature and precipitation in Poland in the period 1951–2000 and their relationship to atmospheric circulation
Authors: Degirmendžić Jan , Kożuchowski Krzysztof , Żmudzka Elwira
Published: March 2004

An analysis of trends of mean monthly temperature and precipitation totals in Poland in the period 1951–2000 was carried out. Areal means of temperature and precipitation were used, averaged for 51 meteorological stations evenly distributed within Poland's borders. Sensitivity of air temperature and precipitation variations towards circulation was assessed. Circulation variations were expressed by sea‐level pressure in the 52.5°N, 20°E grid point and geostrophic wind calculated from meridional (45–60°N) and latitudinal (10–30°E) pressure gradients.

It was shown that the circulation factor explains up to 77% and 44% of temperature and precipitation variance respectively. Significant upward trends of temperature in March and May were detected. Also, the precipitation total in March was on the increase. The last decade of the 20th century was slightly ‘too warm’ in comparison with the circulation‐induced temperature level, as well as with the temperature change scenario according to HadCM2 GS model.

An attempt was made to evaluate the contribution of the frequency of snow cover occurrence to the temperature increase in winter, i.e. the temperature–albedo feedback. Copyright © 2004 Royal Meteorological Society
Fitting multiple datasets in kinetics: n‐butane + OH → products
Authors: Donahue Neil M. , Clarke James S.
Published: March 2004

Offsets due to systematic calibration errors are a common feature of the literature on temperature‐dependent rate constants. We present a formalism for dealing with these offsets within the context of least‐squares fitting, using a priori parameter constraints based on the estimated accuracy of individual studies. This methodology not only eliminates biases caused by calibration errors, it also ensures that the metric used to compare different studies is their accuracy, not their precision. Consequently, studies with single measurements at room temperature can be meaningfully compared with studies comprising dozens of measurements spanning a wide temperature range. We apply this procedure to the complete literature dataset for two reactions: OH + propane and OH + n‐butane, after first presenting new data for OH + n‐butane spanning the temperature range 180–300 K and extending the low‐temperature limit of the literature by 50 K. There is outstanding agreement among a very large set of studies, including relative measurements of the propane:n‐butane rate constant ratio. We present new reduced transition state theory fits for each reaction that accurately reproduce the observed rate constants between 180 and 1000 K, and argue that these two reactions are the optimal reference reactions for many relative rate studies. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 259–272, 2004
Wideband shorted trapezoidal microstrip patch coupled to a hook shape probe
Authors: Kishk Ahmed A. , Lee Kai Fong , Mok W. C. , Luk K. M.
Published: March 2004

A trapezoidal short‐circuited patch excited by a hook‐shaped probe is designed to achieve a wideband performance. The antenna achieves 45% bandwidth with around 4.0‐dB gain. The computed reflection coefficients and radiation patterns are computed and verified experimentally. The main beam of the patch is tilted by about 60° from the broad side. A linear array is analyzed and the array elements are phased to point the main beam to the same direction. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 88–91, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20056
High‐efficiency CPW‐to‐slotline transitions on low εrsubstrates
Authors: Oldenburg M. K. , Weller T. M.
Published: March 2004

The power dissipation characteristics of CPW‐to‐slotline transitions are discussed. The resonant stub chosen to terminate one CPW slot in these transitions has a significant effect on the transition loss. Series‐stub designs are shown to reduce energy loss by 2.5–3 times on a low‐dielectric‐constant substrate, as compared to the more common radial‐stub design. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 91–93, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20057
Demonstration of a highly efficient L‐band erbium‐doped fiber amplifier
Authors: Lu Z. G. , Sun F. G. , Lin P. , Grover C. P.
Published: March 2004

A novel L‐band fiber amplifier comprised of two sections of erbium‐doped fiber (EDF) and an optical reflector is used to enhance power‐conversion efficiency (PCE). We also examine how an optical amplifier can be used without an optical reflector while nonetheless making effective use of amplified spontaneous emission in order to increase the gain. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 96–98, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20059
A novel design method for improvement of narrow bandpass planar filter response
Authors: Prigent G. , Rius E. , Le Pennec F. , Le Maguer S. , Quendo C.
Published: March 2004

This paper discusses a method used to design a planar bandpass filter in the Ku‐band frequency range for a given satellite application. In order to fit a hardened specification, a dual‐behavior‐resonator (DBR)‐based filter topology is employed. In association with this topology, we propose an automated design procedure that combines both circuit and full‐wave simulations. It is based on a statistical sensitivity study performed by DOE analysis. After development of the base filter, the out‐of‐band rejection is improved by using topological modifications in order to favor the occurrence of transmission zeros. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 98–104, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20060
Radiation pattern control for an on‐ceiling omnidirectional monopole antenna
Authors: Liu Yung‐Tao , Su Che‐Wei , Tang Chia‐Luan , Fang Shyh‐Tirng , Wong Kin‐Lu
Published: March 2004

A novel radiation‐pattern control technique for an omnidirectional monopole antenna installed upside down on the ceiling in a building is presented. It is proposed that, by embedding a monopole antenna within a slotted metal cavity comprised of a top reflector, a cavity wall, and a slotted ground plane, the maximum radiation direction and 3‐dB beamwidth of the monopole's radiation pattern can be controlled, thus leading to an enhanced radiation coverage area for practical applications. Details of the proposed pattern control technique are described, and the obtained experimental results are presented. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 106–108, 2004 Published online in Wiley InterScience (www.interscience.wiley.com).DOI 10.1002/mop.20062
Low‐threshold characteristics of a linear‐cavity multiwavelength brillouin/erbium fiber laser
Authors: Al‐Mansoori Mohammed H. , Bouzid Belloui , Saharudin Suhairi , Ali Borhanudin M. , Abdullah Mohamad K. , Mahdi Mohd A.
Published: March 2004

A novel operation scheme of a multiwavelength Brillouin/Erbium fiber laser (BEFL) utilizing a linear cavity is presented. Twenty‐two stable output laser lines with 10.88‐GHz (0.088‐nm) line spacing at 1558 nm were obtained from this architecture without the need of internal feedback. A low threshold of 4‐mW pump power with 2.3‐mW launched Brillouin pump at 1558 nm was obtained. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 114–117, 2004; Published online in Wiley InterScience (www.interscience.wiley.com).DOI 10.1002/mop.20064
Radiation effects on via coupling in power‐return plane structures
Authors: Chen Richard L. , Chen Ji
Published: March 2004

The radiation effect on via coupling in a power‐return plane is studied by using the radial waveguide model combined with the spectral‐domain immittance (SDI) approach. The time‐domain waveform and frequency‐domain response are investigated for cases with or without a consideration of the radiation effects. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 117–119, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20065
Wave propagation along a rectangular metallic waveguide longitudinally loaded with a metamaterial slab
Authors: Cory H. , Shtrom A.
Published: March 2004

Wave propagation along a rectangular metallic waveguide, loaded with a longitudinal metamaterial slab adjacent to air, is studied in this paper. The dispersion relations have been obtained and the β − ω diagrams have been drawn for various width ratios of the metamaterial to air regions. For real propagation coefficients, in the 0 < β < k0 range, the group velocity could be negative, very low or constant, depending on the frequency range and on the width ratios of the two regions. In some cases, it has been found that the propagation coefficient is complex although the media are lossless: there is no net energy flow through any cross section of the guide so that the energy present is only stored reactive energy, and this seems to be due to strong coupling processes occurring in the device. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 123–127, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20067
Microstrip patch antenna array on ground with circular PBG
Authors: Zhang Wenmei , Mao Junfa , Sun Xiaowei , Qian Rong , Zhang Dan
Published: March 2004

In this paper, a microstrip patch antenna array on ground with PBG is simulated and measured. It is shown that the photonic band‐gap (PBG) can suppress harmonics and optimize the current distribution on the patches. As a result, the gain of the antenna array is improved and the side‐lobe level is reduced. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 127–130, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20068
Microstrip stepped‐impedance resonator bandpass filter with over‐coupling structure for suppression of harmonic response
Authors: Weng Min‐Hung , Pan Chi‐Hsiang , Shao Chih‐Wei , Wu Hung‐Wei , Huang Tsung‐Hui
Published: March 2004

This paper describes the microstrip stepped‐impedance resonator (SIR) bandpass filter with an over‐coupling structure for the suppression of spurious response at twice the center frequency (2f0). In addition, the tapped I/O is used in the filter to create the extra transmission zeros to further improve stopband rejection. First, conventional approximate design formulas of microstrip SIR are also presented to predict the filter performance, and then the EM simulation is used to optimize the filter performance. The designed bandpass filters have a wide upper stopband with satisfactory attenuation levels. The experimental results of the two designed filters are in good agreement with the theoretical predictions and simulated results. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 130–133, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20069
Shorted wideband low‐profile patch antenna with two shorting pins
Authors: Li Yuan , Chair R. , Luk K. M. , Lee K. F.
Published: March 2004

This paper presents measured and simulated results for a wideband, low‐profile patch antenna. A low‐profile (0.026λ0) rectangular‐shape patch antenna with two shorting pins and two probe feeds is studied. By exciting one port and terminating the other port by a 50Ω matched load, an impedance bandwidth of as much as 69% is achieving for this antenna. Radiation patterns at different frequencies are presented. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 135–137, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20071
Analysis of multipath fading for six‐port receiver
Authors: Tatu Serioja Ovidiu , Moldovan Emilia , Denidni Tayeb
Published: March 2004

This paper presents simulation and measurement results of a six‐port direct conversion receiver for multipath propagation. Simulation results, using the Norton‐Bullington model of the multipath propagation and the receiver computer model, are presented and compared with bit‐error‐rate (BER) measurement results, performed on a six‐port receiver test setup. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 137–141, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20072
A broadband beam‐fixed planar‐array antenna using slot pair and conductive bar at millimeter‐wave frequencies
Authors: Oh Soonsoo , Heo John , Kim Donghyeon , Lee Jaewook , Song Myungsun , Kim Youngsik
Published: March 2004

This paper presents a broadband millimeter‐wave planar‐array antenna that uses a slot pair and crossing conductive bar. The antenna is fed by a waveguide feed network in the E‐plane to reduce the feed‐line loss and a microstrip‐feed network in the H‐plane in order to decrease fabrication costs. The waveguide and microstrip are coupled through the slot pair, which is placed a quarter guided‐wavelength distance apart, so that the reflected waves from the slots cancel each other. As a result, the antenna exhibits very broadband characteristics. The conductive bar is laid above the slots to increase the coupling. Results from simulation and measurement of the fabricated antenna show the reflection bandwidth to be more than 7.1% of the 40.5–43.5‐GHz frequency range. The antenna also has fixed beams, low side‐lobe levels (SLLs) at all frequencies of interest, and a high gain of 28.1 dBi at 41.5 GHz. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 150–154, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20076
Harmonic suppression by photonic bandgap on CPW‐fed loop‐slot antenna
Authors: Lin Xian‐Chang , Wang Ling‐Teng , Sun Jwo‐Shiun
Published: March 2004

A conventional CPW‐fed loop‐slot antenna, incorporating a PBG structure in the feeding network, is presented. Experimental results show that the PBG structure with cross‐shaped lattices exhibits a well behaved band‐stop characteristic; furthermore, the impedance bandwidth of the proposed antennas also becomes wider than that of the conventional CPW‐fed slot antenna. In this design, the impedance bandwidth can reach 1320 MHz, which is about 60% with respect to the central frequency of 2200 MHz. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 154–156, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20077
Numerical blow‐up for the porous medium equation with a source
Authors: Ferreira Raúl , Groisman Pablo , Rossi Julio D.
Published: March 2004

We study numerical approximations of positive solutions of the porous medium equation with a nonlinear source,

equation image

where m > 1, p > 0 and L > 0 are parameters. We describe in terms of p, m, and L when solutions of a semidiscretization in space exist globally in time and when they blow up in a finite time. We also find the blow‐up rates and the blow‐up sets, proving that there is no regional blow‐up for the numerical scheme. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2004
Respecialization as a school psychologist: Education, training, and supervision for school practice
Authors: Crespi Tony D. , Politikos Natalie N.
Published: March 2004

Professional psychology is facing a looming crisis. On one hand, there is an oversupply of clinical psychologists—a group generally facing decreasing salaries and growing competition. On the other hand, there is a shortage of school psychologists—a group experiencing increasing salaries and expanded role opportunities. Unfortunately, though, educators and practitioners have not fully addressed the issue of respecialization. In a basic way, just as a physician who changes specialties pursues rigorous, 3‐year residency training, so psychologists interested in changing specialties should complete appropriate respecialization. This article explores the issues, controversies, and dynamics involved with respecialization. © 2004 Wiley Periodicals, Inc. Psychol Schs 41: 473–480, 2004.
Farbkränze auf staubigen Gewässern: Spielwiese
Authors: Schlichting Hans Joachim
Published: March 2004

Wenn auf einer Wasseroberfläche feine Staubteilchen liegen, können darauf regenbogenfarbene Ringe entstehen. Sie haben ihre Ursache in einem komplizierten Prozess aus Streuung des Sonnenlichts an den Staubteilchen, Reflexion an der Wasseroberfläche und Interferenz. Fällt das Zentrum eines solchen Farbrings mit dem Reflex der Sonne zusammen, handelt es sich um Fraunhofer‐Beugung; ist der Sonnenreflex exzentrisch, so spricht man von Quételetschen Ringen.
Einsteins Theorie auf dem optischen Prüfstand: Spezielle Relativitätstheorie
Authors: Müller Holger , Peters Achim
Published: March 2004

Licht breitet sich mit konstanter Geschwindigkeit aus, unabhängig von der Ausbreitungsrichtung des Lichtstrahls zum Beobachter und der Relativbewegung. Diese Grundaussage der Speziellen Relativitätstheorie wurde jetzt in einem modernen Michelson‐Morley‐Experiment mit einer Präzision von wenigen Teilen in einer Billiarde bestätigt. Dazu wurden die Resonanzfrequenzen zweier optischer Resonatoren, die auf Temperaturen nahe des absoluten Nullpunktes abgekühlt waren, über mehr als ein Jahr verglichen.
Klassische Fischmechanik
Authors: Vilgis Thomas
Published: March 2004

Will ein Koch einen anderen auf das Gröbste beleidigen, so ist der Vorwurf, jener könne keinen Fisch zubereiten, einer der schlimmsten. Die Physik sagt uns warum: Proteinnetze verändern empfindlich das Biegemodul.
Characteristics of photoconductivity in Tl2S layered single crystals
Authors: Ashraf I. M. , Elshaikh H. A. , Badr A. M.
Published: March 2004

In this work the photoconductivity measurements are carried out for single crystals of the Tl2S compound by using both pulsed excitation (a.c) and steady state (d.c) methods in order to elucidate the nature of photoconductivity (PC) in this compound. Results are reported in the temperature range from 77 K to 300 K, excitation intensity range from 1800 V to 5200 V Lux, applied voltage range from 2 V to 14 V, and wavelength range from 840 nm 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 the carrier lifetime on the light intensity, the applied voltage, and the temperature have also been investigated as results of the ac‐PC measurements. The temperature dependence of the energy gap width has been described as a result of studying the dc‐photoconductivity (dc‐PC). (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Complex dielectric function of AlGaN/GaN/InGaN heterojunction structures
Authors: Jogai B.
Published: March 2004

Theoretical calculations of the complex dielectric function of AlGaN/GaN heterojunction field‐effect transistor (HFETs) structures and InGaN/GaN single quantum wells (SQWs) are presented. The model is based on a self‐consistent calculation of the band structure, taking into account the spontaneous and piezoelectric polarizations and the presence of a two‐dimensional electron gas (2DEG) at the interface. The calculated results show that the large built‐in electric field at the heterojunction smears out any fine structures in the dielectric function that would ordinarily be expected from transitions between the valence band edge and the confined electron states. For HFET structures, two broad features are seen in the calculated spectra, one due to the GaN layer and the other to the AlGaN barrier. There are no features due to the confined states in the 2DEG. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The surface band structure of W(112)
Authors: Losovyj Ya. B. , Yakovkin I. N. , Jeong Hae‐Kyung , Dowben P. A.
Published: March 2004

Both the experimental and theoretical band structure of the W(112) surface are presented, with the theoretical band structure calculated by the film–LAPW (linearized augmented plane waves) method. The results permit one to compare the W(112) and Mo(112) band structures and illuminate the similarities. It is found that for the W(112) surface the main photoemission features combine contributions from both the surface and bulk, as has been previously noted for Mo(112). The main differences between the electronic structures of the furrowed W(112) and Mo(112) surfaces are seen in the width of occupied bands. The differences are attributed to the extent of localization of valence 4d and 5s electrons in Mo and 5d and 6s electrons in W. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Whey protein isolate coating on LDPE film as a novel oxygen barrier in the composite structure
Authors: Hong Seok‐In , Krochta John M.
Published: March 2004

To examine the feasibility of whey protein isolate (WPI) coating as an alternative oxygen barrier for food packaging, heat‐denatured aqueous solutions of WPI with various levels of glycerol as a plasticizer were applied on corona‐discharge‐treated low‐density polyethylene (LDPE) films. The resulting WPI‐coated LDPE films showed good appearance, flexibility and adhesion between the coating and the base film, when an appropriate amount of plasticizer was added to the coating formulations. WPI‐coated LDPE films showed significant decrease in oxygen permeability (OP) at low to intermediate relative humidity, with an Arrhenius behaviour and an activation energy of 50.26 kJ/mol. The OP of the coated films increased significantly with increasing relative humidity, showing an exponential function. Although the coated films showed a tendency to have less oxygen barrier and more glossy surfaces with increasing plasticizer content, differences in the OP and gloss values were not significant. Haze index and colour of the coated films were also little influenced by WPI coating and plasticizer content. The results suggest that whey protein isolate coating could work successfully as an oxygen barrier and have potential for replacing synthetic plastic oxygen‐barrier layers in many laminated food packaging structures. Copyright © 2004 John Wiley & Sons, Ltd.
Health‐related quality of life after restorative proctocolectomy for ulcerative colitis: Long‐term results
Authors: Scarpa Marco , Angriman Imerio , Ruffolo Cesare , Ferronato Antonio , Polese Lino , Barollo Michela , Martin Alessandro , Sturniolo Giacomo C. , D’Amico Davide F.
Published: March 2004

Restorative proctocolectomy (RPC) is the favorite operation for ulcerative colitis, but it may influence health‐related quality of life (HRQL). Our aims were to determine the long‐term HRQL of patients and its modifications after a 5‐year follow‐up and to identify any risk factor for a worse outcome. We enrolled 36 patients submitted to RPC (mean followup 8.4 ± 4.7 years), 36 ulcerative colitis (UC) patients, and 36 healthy subjects. We used a previously validated questionnaire that explored bowel symptoms, systemic symptoms, emotional function, and social function. A series of 17 patients had completed the same questionnaire 5 years earlier. Clinical and surgical factors were investigated. Statistical analysis was performed with Student’s t‐test, Wilcoxon matched‐pairs test, and Fisher’s exact test. The scores of the RPC patients were significantly better than those of moderate or severe UC patients, similar to those with remission/ mild UC, and higher than those of the controls. The scores of patients interviewed 5 years earlier did not change in the present study, except for patients during the first postoperative year, in whom the scores were now significantly better. The analysis of RPC patients in subgroups showed that the use of drugs, high stool frequency, pouchitis, pelvic complications, and younger age at UC diagnosis worsened the HRQL outcome. We concluded that RPC patients, after a long‐term follow‐up, had an HRQL similar to that of the remission/mild UC patients. Recently operated patients improved their quality of life mainly because of improved emotional function, and patients who had been operated on for a longer time maintained their HRQL. HRQL is influenced by drugs, stool frequency, pouchitis, postoperative pelvic complications, and age at diagnosis.
Relaparotomy for suspected intraperitoneal sepsis after abdominal surgery
Authors: Hutchins Robert R. , Gunning M. Paul , Lucas D. Nuala , Allen‐Mersh Timothy G. , Soni Neil C.
Published: March 2004

Relaparotomy may be beneficial in patients developing intraperitoneal sepsis after abdominal procedures. We determined whether joint clinical assessment by intensivist and surgeon (clinician assessment) identified patients with surgically correctable intraperitoneal sepsis. We also assessed the effect of patient age and sex, disease presentation and severity, interval to relaparotomy, and the number of relaparotomies on survival after relaparotomy. Data on clinical, laboratory, and radiologic abnormalities prior to relaparotomy, relaparotomy findings, and in‐hospital survival were prospectively collected on a general hospital intensive care unit (ICU) database between January 1997 and January 2002. Altogether, 65 of 1482 (4.4%) patients admitted to the ICU after abdominal surgery underwent relaparotomy at a median of 5 days after the initial procedure. There was an 83% probability of identifying surgically treatable sepsis and 43% in‐hospital mortality. Abdominal imaging contributed accurate information in 50% of cases where clinician assessment was uncertain. Patient age and multiorgan failure prior to relaparotomy—but not urgency of initial laparotomy or the acute physiology and chronic health evaluation (APACHE II) score prior to relaparotomy, interval to relaparotomy, or number of relaparotomies—affected the outcome. Clinician assessment after abdominal surgery had a high probability of predicting intraperitoneal sepsis at relaparotomy. The 43% mortality after relaparotomy was unlikely to be greater than with nonoperative treatment of intraabdominal sepsis, but the 78% mortality after relaparotomy in patients older than 75 years of age raised doubts about this approach in the elderly. The identification of intraperitoneal sepsis and performance of relaparotomy earlier after the initial abdominal surgery might reduce the high rate (60%) of multiorgan failure prior to relaparotomy and improve survival after it.
Technical performance: Relation between surgical dexterity and technical knowledge
Authors: Bann Simon , Khan Mansoor S. , Datta Vivek K. , Darzi Ara W.
Published: March 2004

Technical performance consists of surgical knowledge, judgment, and dexterity. Although assessment of surgical dexterity is now possible, assessing technical knowledge and its relation to dexterity has not been elucidated. Surgeons of varying experience were recruited to the skills laboratory to undertake three assessments: simple surgical dexterity (at 14 stations scored by motion analysis), an operating room equipment examination, and a novel error analysis. The scores were correlated, and p < 0.05 was deemed to be significant. Thirty surgeons were recruited; and construct validity was exhibited in all areas. Correlations were shown to exist between the two knowledge examinations (Spearman’s rho = 039). Correlations existed between all dexterity task parameters and the equipment examination, whereas they existed for only 15 of the 28 parameters of the error examination and were always weaker. The stronger correlations between dexterity and instrument and operating room (OR) equipment reflect greater surgical experience and time spent in the OR. The weaker correlations between the error analysis and dexterity suggest that these skills are learned at different times. The identification of common surgical errors should be more formally taught to ensure greater uniformity.
After school activities, overweight, and obesity among inner city youth
Authors: Elkins Whitney L , Cohen Deborah A , Koralewicz Lisa M , Taylor Stephanie N
Published: February 2004

We examined the association of adolescent obesity with participation in sports among 5489 low‐income, inner city public high school students. Among inner city youth 28.5% of males and 33.7% of females were overweight and 15.9% of boys and 16.4% of girls were obese. For both males and females, participation in an increasing number of athletic activities was associated with lower (body mass index) BMI after controlling for age, grade, and playing football. While youth with lower BMI might be more likely to participate in sports, after school sports are a potential opportunity for prevention of obesity in adolescents.
Multifocal cardiac Purkinje cell tumor in infancy
Authors: Ottaviani Giulia , Matturri Luigi , Rossi Lino , Lavezzi Anna M. , James Thomas N.
Published: March 2004

Cot death is the commonest form of death among babies in the first year of life. The authors report the unusual case of a 2-month-old female infant dying suddenly and unexpectedly in whom a postmortem histological examination demonstrated a cardiac multifocal Purkinje cell tumor. Necroscopy studies of sudden infant death should always include an accurate histological examination of the cardiac conduction system and brainstem using serial sections.
Radioiodine ablation of the thyroid to prevent recurrence of amiodarone-induced thyrotoxicosis in patients with resistant tachyarrhythmias
Authors: Hermida Jean-Sylvain , Tcheng Emmanuel , Jarry Genevieve , Moullart Veronique , Arlot Sylvie , Rey Jean-Luc , Delonca Jean , Schvartz Claire
Published: March 2004

Amiodarone-induced thyrotoxicosis (AIT) is a common complication of amiodarone therapy. Although permanent withdrawal of amiodarone is recommended due notably to the risk of worsening of tachyarrhythmias, some patients may require the reintroduction of amiodarone several months after normalizing their thyroid function. We, retrospectively, assessed the effects of 131I therapy to prevent recurrence of AIT in euthyroid patients requiring reintroduction of amiodarone.

Subjects and methods

Amiodarone was required in 10 cases of recurrent symptomatic paroxysmal atrial fibrillation (AF) and in 5 cases of ventricular tachycardia (VT) (M=12, F=3, mean age: 63±14 years). The underlying heart disease was dilated cardiomyopathy (n=4), ischaemic heart disease (n=4), hypertensive heart disease (n=2), arrhythmogenic right ventricular dysplasia (n=2) and valvulopathy (n=1). Two patients had idiopathic paroxysmal AF.

Results

A mean 131I dose of 579±183 MBq was administered 34±37 months after the episode of AIT. Amiodarone was reintroduced in 14 of 15 patients after a mean interval of 103±261 d. Fourteen patients developed definite hypothyroidism necessitating l-thyroxine but we observed no late recurrence of AIT. After a mean follow-up of 22±16 months, tachyarrhythmias were controlled in 12 of 14 patients.

Conclusion

131I therapy appears to be an effective and safe approach to prevent the recurrence of AIT in a patient requiring the reintroduction of amiodarone for tachyarrhythmias.
Computerized high-density mapping of the pulmonary veins: new insights into their electrical activation in patients with atrial fibrillation
Authors: De Ponti Roberto , Tritto Massimo , Lanzotti Marcelo E. , Spadacini Giammario , Marazzi Raffaella , Moretti Paolo , Salerno-Uriarte Jorge A.
Published: March 2004

Aim

To report the method and findings of computerized high-density mapping of pulmonary veins (PVs) in patients undergoing their electrical isolation for atrial fibrillation (AF).

Methods and results

In 17 consecutive patients (8 M, age 55±11 years), a 64 electrode basket catheter was placed in the target PVs and 56 bipolar electrograms were recorded, analyzed and isochronal maps were generated. PVs were mapped during sinus rhythm, left-sided pacing and ectopic activity. The sites of earliest activation at the veno-atrial junction were defined as the atrium to vein conduction breakthroughs. PV activation pattern was classified as predominantly longitudinal or transverse, according to the direction of the impulse from the breakthroughs. The ectopic pattern was defined as multifocal, when distant areas in the PV had activation times within 10 ms. Thirty-one PVs were mapped. The activation pattern was predominantly longitudinal in 13 PVs and transverse in 18 PVs. Two breakthroughs were identified in 22 PVs and three in nine. All the breakthroughs were evident simultaneously in sinus rhythm and left-sided pacing changed only the predominance of the breakthrough. Ectopies were mapped in 10 PVs: eight showed a multifocal and two a monofocal pattern; six ectopies originated from the proximal tract of the PV.

Conclusion

High-density mapping of PV identifies a typical activation pattern. Multiple and discrete breakthroughs are simultaneously identified in sinus rhythm. The majority of the mapped ectopies has a multifocal pattern and proximal origin.
ECT response after relapse during continuation repetitive transcranial magnetic stimulation. A case report
Authors: Conca A. , Hrubos W. , Di Pauli J. , König P. , Hausmann A.
Published: February 2004

Research on repetitive transcranial magnetic stimulation (rTMS) indicates that the treatment of non-psychotic depression is comparable to electroconvulsive therapy (ECT) in terms of short-term outcome. We report on a woman who exerted a recurrent moderate major depressive episode, 6 months after discontinuation of maintenance ECT. She responded to acute rTMS treatment which was followed by the rTMS maintenance-protocol. Within 2 months of continuation rTMS she relapsed suffering from a severe non psychotic depressive episode and had to be switched to a successful ECT. In this patient rTMS had a good clinical impact as an acute treatment strategy, but failed to prevent relapse as the continuation ECT previously did in the same patient.
Novelty seekers and impulsive subjects are low in morningness
Authors: Caci Hervé , Robert Philippe , Boyer Patrice
Published: February 2004

The bipolar dimension of morningness–eveningness refers to the preferred times of day for achieving various activities (i.e. the phase of the circadian clock). It is validated from a biological point of view, associated with at least one gene and heritable through an epistatic mechanism. It has been used as a proxy to study the relationships between the circadian system, personality and psychopathology: there is a correlation between the evening orientation and depression, extraversion and, probably, impulsivity. Furthermore, there is a possible relationship with temperament in children as theorized by Thomas and Chess. In this paper, we expanded on the hypothesis that impulsive subjects are low in morningness by performing a factor analysis of the Composite Scale of Morningness, Cloninger’s temperament and character inventory, and Spielberger’s trait anxiety inventory in a sample of 129 males. The results can probably be extended to women. Morningness is negatively correlated with novelty seeking (which includes an impulsivity facet), positively correlated with persistence, and independent of character dimensions and trait anxiety. Future research may focus in the involvement of the circadian system in these personality dimensions and facets, and the benefits of adding chronotherapic manipulations in the treatment of the personality disorders.