bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonlinear equivalent circuits of acoustic devices
Authors: Cho Yasuo , Wakita Junji
Published: July 2007

Mason's equivalent circuit is well known as a linear equivalent circuit for acoustic devices. By combining Mason's equivalent circuit with Smith's equivalent circuit of surface acoustic wave devices, it becomes a very effective tool for the physical interpretation of acoustic devices.

If such equivalent circuit analysis can also be performed for the nonlinear problem, then comparatively simpler and accurate analysis can be obtained for almost all types of nonlinear problems.

In this paper, equations are formulated to analyze the equivalent circuit of nonlinear‐type acoustic devices. At first, Mason's equivalent circuit is extended to the nonlinear region for the basic circuits of a thin bar of length‐extensional vibration and a broad plate of thickness‐extensional vibrations.

Next, this equivalent circuit is used to analyze the thickness‐extensional vibration of Z‐cut LiNbO3 and second harmonic generation at the resonance point is clarified. Finally, these nonlinear equivalent circuits of length‐extensional vibration are applied to determine the nonlinear constants of PZT ceramics and the nonlinear constants of the equivalent circuit are clarified.
On the availability of trellis decoding schemes for continuous phase FSK signals employing limiter discriminator detection
Authors: Iwanami Yasunori
Published: July 2007

Although a trellis‐coded modulation scheme has been applied to multilevel PSK or QAM signals, its application for the continuous‐phase FSK (CPFSK) with the limiter‐discriminator detection has not been investigated well and the coding gain associated with it has not been obvious yet. In this paper, using a linear approximation, we have designed modulation parameters of this scheme. We have also executed the exact computer simulation and made clear the problem to obtain the actual coding gain as well as to increase them. Furthermore, utilizing the intersymbol interference caused by the IF filter, which greatly deteriorates the bit error rate (BER) performance in this scheme, we have proposed a sequence estimation scheme using the Viterbi algorithm. In this scheme, the sending signals are those of the binary continuous phase FSK. Through computer simulations, we have made clear that large improvements of BER really exist. The sequence estimation scheme is considered to work better than the trellis encoded scheme when considering the BER performance and the complexity of transmitter and receiver.
Evaluation method of shielding performance of cubic magnetically shielded room—simulation of magnetic field analysis with finite element method
Authors: Ishikawa Noboru , Kasai Naoko , Kado Hisashi , Koyanagi Masao , Higuchi Masanori
Published: July 2007

The shielding factor of a large magnetically shielded room (MSR) cannot be measured by the usual methods. Successful results have been achieved by magnetic field analysis using the finite element method. Investigation of the shielding factor of an MSR included examination of: (1) a uniform magnetic field; (2) a magnetic field produced by an electric current flowing in a single circular coil (single‐coil field); and (3) a magnetic field produced by electric current flowing in a pair of Helmholtz coils (pair coil field).

As a result, it was found that the shielding factor within MSRs varies with both the external magnetic field distribution condition and the position being measured within the MSR. The shielding factor at the center (when due to a uniform magnetic field) is lower than the shielding factor at the center when the field is produced by circular coils. The approximate equation expressing the ratio of the shielding factor due to the field of a circular current and that due to a uniform field using the center of the MSR as the measurement point was deduced as a function of the circular coil radius and its position. The method of evaluation of shielding performance of a cubic‐shaped MSR involves measuring the shielding factor due to the field produced by a circular coil and then transforming the results to yield the shielding factor for a uniform field. The approximate equation obtained thusly produces standardized shielding performance.
A discrete logarithm problem over composite modulus
Authors: Murakami Yasuyuki , Kasahara Masao
Published: July 2007

Recently, many applications of integer theory to cryptographic techniques have been observed. The discrete logarithm problem is one such case. Usually, the discrete logarithm problem is the determination of the logarithm for the given arbitrary element with a prime number as the modulus. However, the discrete logarithm problem can also be considered with a composite number as the modulus. It is anticipated that the discrete logarithm problem with a composite number as the modulus is a difficult problem if the prime factors of the composite number, which is used as the modulus, are unknown. Then the problem can be applied to the cryptography.

In the general discrete logarithm problem with a composite number as the modulus, it is not always true that an arbitrary element has a logarithm. From such a viewpoint, this paper shows that the exponent of an arbitrary element belonging to the irreducible residue class with a composite number as the modulus has a logarithm. Then the necessary condition in the application to the cryptographic technique is presented.

Finally, as an application example of the technique proposed in this paper, a cryptographic technique based on the discrete logarithm problem with the composite number as the modulus is shown.
Construction of arbitrary transfer functions with complex coefficients using wave digital filters
Authors: Morimoto Etsuo , Takahashi Shin‐Ichi , Takeuchi Hirokazu
Published: July 2007

This paper proposes an extension of the real‐coefficient wave digital filter by Fettweis et al. (WDF) to the complex‐coefficient WDF (CWDF) as well as a construction method to realize an arbitrary complex‐coefficient transfer function.

The first step of the proposed construction method is to synthesize the lossless reactance circuit containing the imaginary resistors (except for the input terminal) as an analog reference circuit by the continued‐fraction expansion.

In this study, the LC ladder network containing imaginary resistors is synthesized as the reference network, realizing the denominator polynomial of the transfer function. Then the state‐variable representation is constructed and the numerator polynomial is realized by determining the tap coefficients to the external output, using the transform matrix.

In this process, the reference network is transformed into WCDF, and the tap is formed considering the relation between incident/reflected waves and the terminal voltages. By this procedure, the required transfer function can be realized. Finally, the proposed method is compared to other construction methods and the low‐sensitivity property of the proposed method is demonstrated.
A simple construction for a family of collision‐intractable hash functions
Authors: Itoh Toshiya , Takeda Makoto
Published: July 2007

To design a reliable system, it is very important to protect data stored or transmitted from intentional forgery in communications network. As a practical means of protecting data or software, it is pointed out by Naor and Yung that a family of one‐way hash functions is useful and can be classified into a universal one‐way hash function family (UOHF) and a collision intractable one‐way hash function family (CIHF). The construction for a UOHF is possible under a weak assumption, i.e., one‐way functions exist. However, the construction for a CIHF is not known to be possible under such a weak assumption.

This paper presents a simple construction for a CIHF that is based on the hardness of factoring large composite numbers. The idea on the construction here is completely different from those reported so far and can be expected to provide a theoretical breakthrough to the construction for a CIHF under a general assumption.
Design of 2‐D perfect reconstruction filter banks for arbitrary sampling lattices—design of 2‐D N‐th‐band digital filters
Authors: Ikehara Masaaki , Sawada Kiyoshi , Isobe Hiroyuki , Yamashita Akinobu , Kuroda Hideo
Published: July 2007

This paper presents a design method of two‐dimensional (2‐D) perfect reconstruction filter banks for arbitrary sampling lattices. First, a design of 2‐D N‐th‐band digital filters with arbitrary sampling lattices is shown. Next, the relation between the sampling matrix and the number of paths is presented and the band‐limited region and the condition of delays are defined. From these conditions, the approximation problem is shown of the 2‐D allpass filter whose 2‐D N‐th‐band filter is composed and the characteristics of 2‐D N‐th‐band filters are explained. Then 2‐D analysis banks consist of 2‐D discrete Fourier transform (DFT) and 2‐D N‐th‐band filter which consists of some delays and 2‐D interpolated allpass networks. To achieve the perfect reconstruction, by evaluating the aliasing component matrix, it is shown that the synthesis banks can also be constructed the same as the analysis bank.
A study for new operator representation on the linear attenuation quantum channel
Authors: Osaki Masao , Nakagawa Masao , Hirota Osamu , Ojima Izumi
Published: July 2007

In the area of quantum communication, a situation often arises in which the inner product between the input and output signal quantum states of the channel is not preserved. In this paper, such a quantum channel is treated as a conditional unitary process which is proposed by one of the authors. As a new operator representation to explain this process, the condition unitary operator is derived.

Based on the definition of the conditional unitary process, a method is presented for constructing the conditional unitary operator. Next, it is shown that the energy attenuation process of which the analysis is indispensable in the area of quantum communication is a conditional unitary process for the coherent state as a representative input quantum state, photon number state, and squeezed state and that the process can be described by the conditional unitary operation derived by the present method.
A General Approach to the Synthesis of Substituted Isoxazolo[4,3‐c]quinolines via Chalcones
Authors: Madapa Sudharshan , Sridhar Divya , Yadav Gaya P. , Maulik Prakas R. , Batra Sanjay
Published: July 2007

A general and practical approach to the synthesis of substituted isoxazolo[4,3‐c]quinolines from the substituted isoxazolines obtained by 1,3‐dipolar cycloadditions between2‐nitrobenzonitrile oxide and chalcones is described. SnCl2·2H2O‐mediated reduction of the nitro group, followed by intramolecular cyclization involving the amino and the keto groups in these substrates, furnished mixtures ofisoxazolo[4,3‐c]quinolines and 3,5‐dihydroisoxazolo[4,3‐c]quinolines. In contrast, the reduction of these substrates with Fe/AcOH unexpectedly yielded 3‐benzoylquinolin‐4‐ylamine derivatives.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
In Situ Generation of Nitroso Compounds from Catalytic Hydrogen Peroxide Oxidation of Primary Aromatic Amines and Their One‐Pot Use in Hetero‐Diels–Alder Reactions
Authors: Zhao Dongbo , Johansson Mikael , Bäckvall Jan‐E.
Published: July 2007

A method for in situ generation of nitroso compounds from organoselenium‐catalyzed oxidation of anilines by hydrogen peroxide was developed. The generated nitroso compounds were subsequently used in hetero‐Diels–Alder reactions. A variety of oxazines were synthesized in reasonable to good yields by this one‐pot procedure using primary aromatic amines with different substituents and various conjugated dienes. This strategy might facilitate the current methodologies for nitroso chemistry since no isolation or purification of the nitroso compounds is required. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
New Fully Portable Instrument for the Versatile Determination of Cations and Anions by Capillary Electrophoresis with Contactless Conductivity Detection
Authors: Kubáň Pavel , Nguyen Huong Thi Anh , Macka Mirek , Haddad Paul R. , Hauser Peter C.
Published: July 2007

A new portable capillary electrophoresis instrument with capacitively coupled contactless conductivity detection was developed and optimized for the sensitive field measurements of ionic compounds in environmental samples. It is powered by batteries and the high voltage modules are capable of delivering up to 15 kV at either polarity for more than one working day. Inorganic cations and anions, including ions of heavy metals and arsenate, could be determined with detection limits in the range from about 0.2 to 1 μM. The instrument was field tested in a remote region of Tasmania and nitrite and ammonium could be determined on‐site at concentrations as low as 10 ppb in presence of other common inorganic ions at concentrations which were 2 to 3 orders of magnitude higher.
A high‐order triangular discontinuous Galerkin oceanic shallow water model
Authors: Giraldo F. X. , Warburton T.
Published: July 2007

A high‐order triangular discontinuous Galerkin (DG) method is applied to the two‐dimensional oceanic shallow water equations. The DG method can be characterized as the fusion of finite elements with finite volumes. This DG formulation uses high‐order Lagrange polynomials on the triangle using nodal sets up to 15th order. Both the area and boundary integrals are evaluated using order 2N Gauss cubature rules. The use of exact integration for the area integrals leads naturally to a full mass matrix; however, by using straight‐edged triangles we eliminate the mass matrix completely from the discrete equations. Besides obviating the need for a mass matrix, triangular elements offer other obvious advantages in the construction of oceanic shallow water models, specifically the ability to use unstructured grids in order to better represent the continental coastlines for use in tsunami modeling. In this
paper, we focus primarily on testing the discrete spatial operators by using six test cases—three of which have analytic solutions. The three tests having analytic solutions show that the high‐order triangular DG method exhibits exponential convergence. Furthermore, comparisons with a spectral element model show that the DG model is superior for all polynomial orders and test cases considered. Copyright © 2007 John Wiley & Sons, Ltd.
The period of hypotension following orthostatic challenge is prolonged in dementia with Lewy bodies
Authors: Andersson M. , Hansson O. , Minthon L. , Ballard C.G. , Londos E.
Published: July 2007

Objectives

To determine whether orthostatic hypotension (OH) is more common in patients with dementia than in older people without cognitive impairment and to identify key differences in the profile of the orthostatic response and the pulse drive during orthostatic challenge between Alzheimer's disease (AD) and dementia with Lewy bodies (DLB).

Methods

The orthostatic response was evaluated in 235 patients with AD, 52 patients with DLB and 62 elderly controls. The blood pressure and pulse rate were measured in supine position, immediately after standing up and after 1, 3, 5 and 10 min of standing. OH was defined as a reduction of systolic blood pressure (SBP) of at least 20 mm Hg or a reduction of diastolic blood pressure (DBP) of at least 10 mm Hg.

Results

OH occurred in 69% of the DLB patients and in 42% of the AD patients, but only in 13% of the controls (p < 0.001 controls vs AD and controls vs DLB, p = 0.001 AD vs DLB) The DLB patients had a greater drop in SBP than the other study groups during orthostatic challenge and had a more prolonged period of orthostasis. The pulse drive on orthostatic challenge was similar in between groups. However, in the DLB group it was not adequate to restore the blood pressure to supine values.

Conclusions

Patients with DLB react different to orthostatic challenge than patients with AD or controls, with important clinical implications for key disease symptoms and treatment. Copyright © 2007 John Wiley & Sons, Ltd.
Insomnia and daytime sleepiness in people with dementia residing in assisted living: findings from the Maryland Assisted Living Study
Authors: Rao Vani , Spiro Jennifer , Samus Quincy M. , Steele Cynthia , Baker Alva , Brandt Jason , Mayer Lawrence , Lyketsos Constantine G. , Rosenblatt Adam
Published: July 2007

Objective

To estimate the frequency and correlates of insomnia and daytime sleepiness among people with dementia in AL facilities.

Methods

Participants were randomly selected from 22 different assisted living facilities in Maryland. A total of 124 dementia participants were included in the analysis. All participants were rated on an 11‐item sleep questionnaire regarding insomnia and daytime sleepiness.

Results

Sleep disturbance was present in 59.2% of people with dementia. Of the total sample, 21.8% had insomnia only (IN); 21.6% had excessive daytime sleepiness only (DS); and 16.8% had both IN and DS. 40.8% had no sleep disturbance. IN and DS scores were not significantly associated with each other (r = 0.07, p = 0.43). Of those in the IN group, the majority had mild and moderate dementia and of those in the DS only group the majority had severe dementia. Those with IN only performed the best and DS only performed the worst on both cognitive measures (the Mini Mental State Examination) (F = 3.26, p = 0.014), and on physical measures (the physical subscale of the psychogeraitric dependency rating scale) (F = 6.09, p < 0.001). There was no significant difference between the groups on the Cornell scale for depression in dementia.

Conclusion

The frequency of insomnia and daytime sleepiness in dementia subjects in AL is similar to that found in nursing homes. Daytime sleepiness is associated with poorer cognitive and day‐to‐day functioning. Effective management of DS may lead to improved functioning in the AL residents. Insomnia is associated with the best outcomes, even better than those with no sleep disturbance. This finding needs to be replicated. Copyright © 2007 John Wiley & Sons, Ltd.
Chiral sulfur‐containing structures: Selected synthetic and structural aspects
Authors: Drabowicz Józef , Zając Adrian , Krasowska Dorota , Bujnicki Bogdan , Dudziński Bogdan , Janicka Magdalena , Mikołajczyk Marian , Chmielewski Marek , Czarnocki Zbigniew , Gawroński Jacek , Polavarapu Prasad L. , Wieczorek Michał W , Marciniak Bernard , Sokołowska‐Różycka Ewa
Published: July 2007

Synthetic procedures applied for the preparation of a new diastereomerically pure sulfinate and amidosulfite and a few enantiomerically pure sulfinyl derivatives, including sulfoxides functionalized with a perfluorocumyl substituent, are presented. Attempts to polymerize optically active 2‐(3‐thienyl)ethyl p‐tolyl sulfoxide are also mentioned. Mechanistic and stereochemical aspects of the presented protocols are discussed. Structural studies, which include the X‐ray, circular dichroism, and vibrational circular dichroism‐‐based determinations of the absolute configurations at the stereogenic sulfur atoms and calculations of conformational equilibria for a few model sulfur‐containing compounds are also described. The use of optically active t‐butylphenylthiophosphinic acid as a chiral solvating agent is illustrated. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:527–536, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20335
Fascinating organosulfur functionalities: Polychalcogens as diatomic sulfur sources
Authors: Zysman‐Colman Eli , Harpp David N.
Published: July 2007

Recent work on the chemistry of dialkoxy disulfides is summarized. It includes various aspects of their structure and relationship to the isomeric thionosulfites as well as their use as diatomic sulfur precursors. © 2007 Wiley Periodicals, Inc. 18:449–459, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20341
Thiosilanes in sulfur chemistry: A general approach to silyl thiaheterocycles and their use in stereoselective synthesis
Authors: Capperucci Antonella , Degl'Innocenti Alessandro , Pollicino Salvatore , Acciai Miriam , Castagnoli Giulio , Malesci Irene , Tiberi Caterina
Published: July 2007

2‐Silyl five‐membered sulfurated heterocycles can be efficiently accessed through reaction of bromo(methoxy)methyl trimethylsilane with suitable β‐substituted mercaptans HS‐CH2CH2‐XH, leading to the formation of 2‐silyl‐1,3‐dithiols, 2‐silyl‐1,3‐thiazolidines, and 2‐silyl‐1,3‐oxathiolanes. β‐Mercaptoalcohols are obtained through regioselective ring opening of epoxides with bis(trimethylsilyl)sulfide (HMDST). In a similar way, thiiranes and aziridines react with HMDST, leading to the formation of 1,2‐dithiols and β‐aminothiols. Fluoride ion induced functionalization of the pentaatomic heterocycles smoothly affords the transfer of the heterocyclic ring on electrophiles, thus showing these silyl derivatives as a new class of acyl anion equivalents. When stereodefined compounds are reacted, the stereoinformation is transferred from the carbon–silicon to the newly formed carbon–carbon bond. © 2007 Wiley Periodicals, Inc. 18:516–526, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20345
A complex associative structure formed in the mammalian brain during acquisition of a simple visual discrimination task: Dorsolateral striatum, amygdala, and hippocampus
Authors: McDonald Robert J. , King Amy L. , Wasiak Tamara D. , Zelinski Erin L. , Hong Nancy S.
Published: July 2007

A review of empirical evidence supporting the multiple memory systems view of the organization of learning and memory in the mammalian brain is presented as a powerful component of a broader foundation of basic scientific information necessary for understanding human behavior. However, it is argued that there are significant gaps in our knowledge about these different learning and memory systems, how they interact with one another, and how they interact with the rest of the brain. To demonstrate how little we know about these complex processes, this article reviews recent evidence showing the complexity of associative structure formed during the acquisition of a simple visual discrimination task. The results show that the dorsolateral striatum is necessary for the acquisition of this task but that both the amygdala and hippocampus incidentally acquire and store information during this training period. A new experiment is also presented showing that rats with complete or partial (dorsal vs. ventral) hippocampal lesions show a retrograde amnesic effect on the simple visual discrimination task despite the fact that these same lesions produce no impairment in the anterograde direction. Evidence is presented in support of one interpretation of this effect suggesting that the retrograde amnesia occurs, at least in part, because the hippocampus acquires a context‐specific inhibitory association during original training. Although this representation is not required for acquisition of the task in the anterograde direction, removal of this representation has a disruptive effect on expression of the task. © 2007 Wiley‐Liss, Inc.
Inhibition of human cytochrome p450 1b1 further clarifies its role in the activation of dibenzo[a,l]pyrene in cells in culture
Authors: Mahadevan Brinda , Luch Andreas , Atkin Jennifer , Haynes Melanie , Nguyen Tuan , Baird William M.
Published: July 2007

Metabolic activation and DNA adduct formation of the carcinogenic aromatic hydrocarbon dibenzo{a,l}pyrene (DBP) was investigated in human mammary carcinoma MCF‐7 cells and human cytochrome P450 (CYP) 1B1‐expressing Chinese hamster V79 cells in culture. It has been shown that DBP is metabolically activated to DNA‐binding diol epoxides both in vitro and in vivo. To further establish the role of human CYP1B1 in the activation of DBP, both cell lines were cotreated with DBP and a selective chemical inhibitor of CYP1B1, 2,4,3′ ,5′‐tetramethoxy‐stilbene (TMS). Results from DBP–DNA adduct analyses revealed the complete inhibition of DNA binding when cells were cotreated with DBP and TMS in comparison to DBP alone. Inactivation of CYP1B1 by TMS was also demonstrated through a decrease in the 7‐ethoxyresorufin O‐deethylase (EROD) activity in microsomes isolated from these cells. Emodin, 3‐methyl‐1,6,8‐trihydroxyanthraquinone, an active ingredient of an herb, has been recently shown of being able to induce CYP1 gene expression. Examination of human CYP1B1 induction and EROD activity confirmed an increase in protein levels upon cotreatment with emodin and DBP. Despite increases in protein levels and enzyme activity, there was no significant change in DBP–DNA binding levels at very low substrate concentrations (17 nM). The data obtained in this study emphasize the central role of CYP1B1 in the activation of DBP in human cells in culture. © 2007 Wiley Periodicals, Inc. J Biochem Mol Toxicol 21:101–109, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20168
“Panic”: The impact of Le Bon's crowd psychology on U.S. military thought
Authors: Bendersky Joseph W.
Published: July 2007

The controversial crowd psychology of Gustave Le Bon has been both praised as an incisive contribution to social theory and also condemned as a doctrine of irrationality and mass manipulation associated with fascism. New archival documentation now demonstrates that Le Bon exercised significant influence on U.S. military thinking and practice through World War II. Army writings and officer training on morale, leadership, and battlefield psychology rested substantially on his theory of crowds, particularly regarding races and panic. Le Bon's racial psychology took on additional importance when the African‐American 92nd Infantry Division panicked during combat in Italy. This new evidence offers an excellent case study of the direct and enduring impact of a peculiar type of social psychology on the institutional culture of the army from the classrooms at the Army War College to the battlefield itself. © 2007 Wiley Periodicals, Inc.
Artifacts and pitfalls in MR imaging of the pelvis
Authors: Rafat Zand Khashayar , Reinhold Caroline , Haider Masoom A. , Nakai Asako , Rohoman Laurian , Maheshwari Sharad
Published: July 2007

Artifacts are intimately intertwined with MRI. For the practicing radiologist, effective supervision, troubleshooting, and interpretation of diagnostic MR studies require a solid knowledge of the pertinent artifacts. This article seeks to familiarize the reader with commonly encountered artifacts and pitfalls in pelvic imaging, the mechanism behind their generation, and methods of minimizing their negative impact or maximizing their diagnostic yield. It also serves as an exciting tool to learn many aspects of basic and advanced MR physics. Artifacts are categorized into patient‐ and sequence‐related artifacts. Various manifestations of motion and vascular artifacts, susceptibility, altered tissue contrast, blurring, chemical shift artifact, volume averaging, and gadolinium (Gd) pseudolayering are explained, along with their proposed remedies. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Double‐subtraction maximum intensity projection MR angiography for detecting the artery of Adamkiewicz and differentiating it from the drainage vein
Authors: Hyodoh Hideki , Shirase Ryuji , Akiba Hidenari , Tamakawa Mitsuharu , Hyodoh Kazusa , Yama Naoya , Shonai Takaharu , Hareyama Masato
Published: July 2007

Purpose

To evaluate the efficacy of double‐subtraction magnetic resonance angiography (MRA) (subtraction of the subtracted venous phase image from the subtracted arterial dominant phase image) for depicting the artery of Adamkiewicz and differentiating it from the drainage vein.

Materials and Methods

A total of 170 patients (123 men, 47 women; aged 17–84 years, mean = 67 years), with a thoracoabdominal vascular lesion underwent MRA for detection of the artery of Adamkiewicz. MRA was performed as a five‐phase dynamic‐enhanced three‐dimensional (3D) fast spoiled gradient recalled acquisition in steady state (GRASS) sequence on a 1.5‐T system, with double‐dose bolus contrast and saline injection. The levels at which the artery of Adamkiewicz and drainage vein originated were determined. Signal intensities of the two vessels were measured with source images to assess the signal‐to‐noise ratio (SNR), contrast‐to‐noise ratio (CNR), and necessity of the double‐subtraction technique.

Results

The artery of Adamkiewicz was detected in 140 patients (82.4%). Branching occurred at levels T8–T12 on the left and T8–T11 on the right. An additional anterior radiculomedullary artery was detected in 18 patients. The drainage vein was detected in 133 patients (78.2%). It merged at the T9–L2 level on both sides. In six of the 133 patients (4.5%), the drainage vein branched upwardly. Neither SNR nor CNR differed significantly between the artery of Adamkiewicz and the drainage vein in the arterial phase; but on the subtraction image, signal intensity of the artery was higher than that of the drainage vein (P < 0.05).

Conclusion

Double‐subtraction MRA is useful for detecting the artery of Adamkiewicz when it is necessary to differentiate it from the drainage vein. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Snake venomics. Strategy and applications
Authors: Calvete Juan J. , Juárez Paula , Sanz Libia
Published: July 2007

Snake bites can be deadly, but the venoms also contain components of medical and biotechnological value. The proteomic characterization of snake venom proteomes, snake venomics, has thus a number of potential benefits for basic research, clinical diagnosis, and development of new research tools and drugs of potential clinical use. Snake venomics is also relevant for a deep understanding of the evolution and the biological effects of the venoms, and to generate immunization protocols to elicit toxin‐specific antibodies with greater specificity and effectiveness than conventional systems. Our snake venomics approach starts with the fractionation of the crude venom by reverse‐phase HPLC, followed by the initial characterization of each protein fraction by combination of N‐terminal sequencing, SDS‐PAGE, and mass spectrometric determination of the molecular masses and the cysteine (SH and SS) content. Protein fractions showing a single electrophoretic band, molecular mass, and N‐terminal sequence can be straightforwardly assigned by BLAST analysis to a known protein family. On the other hand, protein fractions showing heterogeneous or blocked N‐termini are analyzed by SDS‐PAGE and the bands of interest subjected to automated reduction, carbamidomethylation, and in‐gel tryptic digestion. The resulting tryptic peptides are then analyzed by MALDI‐TOF mass fingerprinting followed by amino acid sequence determination of selected doubly and triply charged peptide ions by collision‐induced dissociation tandem mass spectrometry. The combined strategy allows us to assign unambiguously all the isolated venom toxins representing over 0.05% of the total venom proteins to known protein families. Protocols and applications of snake venomics are reviewed and discussed. Copyright © 2007 John Wiley & Sons, Ltd.
MALDI‐ion mobility‐TOFMS imaging of lipids in rat brain tissue
Authors: Jackson Shelley N. , Ugarov Michael , Egan Thomas , Post Jeremy D. , Langlais Denis , Albert Schultz J. , Woods Amina S.
Published: July 2007

While maintaining anatomical integrity, matrix assisted laser desorption/ionization mass spectrometry (MALDI‐MS) has allowed researchers to directly probe tissue, map the distribution of analytes and elucidate molecular structure with minimal preparation. MALDI‐ion mobility (IM)‐orthogonal time‐of‐flight mass spectrometry (oTOFMS) provides an advantage by initially separating different classes of biomolecules such as lipids, peptides, and nucleotides by their IM drift times prior to mass analysis. In the present work the distribution of phosphatidlycholine and cerebroside species was mapped from 16 µm thick coronal rat brain sections using MALDI‐IM‐oTOFMS. Furthermore, the use of gold nanoparticles as a matrix enables detection of cerebrosides, which although highly concentrated in brain tissue, are not easily observed as positive ions because of intense signals from lipids such as phosphatidlycholines and sphingomyelins. Copyright © 2007 John Wiley & Sons, Ltd.
Aroma series as fingerprints for biological ageing in fino sherry‐type wines
Authors: Zea Luis , Moyano Lourdes , Moreno Jose A , Medina Manuel
Published: July 2007

BACKGROUND: The contribution of flor yeasts and wood to the ageing of fino sherry type wines was studied by using capillary column gas chromatography to analyse 72 aroma compounds in wines subjected to biological ageing. The odour activity values (OAVs) for the different compounds were classified into eight odorant series that describe the aroma profile of these wines (fruity, chemical, balsamic, vegetable, fatty, empyreumatic, floral and spicy).

RESULTS: The fruity samples made up the major series followed by the fatty and spicy at the end of the ageing period. The application of a linear regression model to the OAVs for the different series revealed that the fruity series, which is related to the flor yeasts activity, and the spicy series, which includes the compounds released by wood, are those most closely representing the changes in the aroma of these wines during their ageing.

CONCLUSIONS: The comparison of the OAVs for fruity and spicy series along the ageing period can be used to establish a balance between the aroma compounds contributed by the flor yeasts and those extracted from the wood. This balance should be particularly considered in works aimed at shortening the ageing time for these wines. Copyright © 2007 Society of Chemical Industry
Experimental investigation of the intermediates of isooctane during ignition
Authors: He X. , Walton S. M. , Zigler B. T. , Wooldridge M. S. , Atreya A.
Published: July 2007

Direct measurements of intermediates of ignition are challenging experimental objectives, yet such measurements are critical for understanding fuel decomposition and oxidation pathways. In the current work, a new gas‐sampling system is used to provide quantitative discrete measurements of 30 hydrocarbon and oxygenate species during rapid compression facility studies of isooctane ignition. Two target conditions and equivalence ratios (based on molar fuel to oxygen ratio) were studied (P = 5.2 atm, T = 1000 K, ϕ = 0.4 and P = 4.8 atm, T = 975 K, ϕ = 1.2). The results are compared with model predictions that use the detailed reaction mechanism developed by Curran et al. (Combust Flame 2002, 129, 253–280). In general, the model predictions are in excellent agreement with the experimental data, including several trace species. Isobutene (i‐C4H8) and propene (C3H6) were the major olefin species identified in the experiments. The results are consistent with an intermediate temperature reaction path sequence, where isooctane is consumed by H‐atom abstraction to yield isooctyl radicals that undergo β‐scission to form olefin and alkyl radical species. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 498–517, 2007
Thermochemistry of methyl and ethyl esters from vegetable oils
Authors: Osmont Antoine , Catoire Laurent , Gökalp Iskender
Published: July 2007

This paper deals with the gas‐phase thermodynamic properties of methyl ester and ethyl ester of vegetable oils (fatty acid methyl esters and fatty acid ethyl esters respectively) present in biodiesel. The standard enthalpies of formation at 298.15 K, heat capacities, and entropies in the temperature range 300–5000 K are determined by means of quantum chemistry calculations along with a protocol developed for these compounds. The resultant data, currently not available in the literature for most of them, are critical to the modeling of combustion chemistry of the subject compounds. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 481–491, 2007
An analytical solution for the kinetics of AB(1k,1ϕ) systems and its application to a spirobenzopyran
Authors: Maafi M. , Brown R. G.
Published: July 2007

A new, rapid method is described which determines the absolute values of all the unknown parameters of an AB(1k,1ϕ) reactive system from experimental information about the change of absorbance with time at any given wavelength. The mathematical algorithm is given for the case where the spectrum of the isomer B is not experimentally accessible and overlaps the spectrum of A. An example of its application to a photochromic spiropyran derivative is given. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 539–545, 2007
Water points and their influence on grazing resources in central northern Namibia
Authors: Klintenberg P. , Verlinden A.
Published: July 2007

Debate among scientists about ecological dynamics and appropriate management of semi‐arid rangelands has led to a challenge of received wisdoms of range management and pastoral development in dryland Africa. In our study, we investigated impacts of grazing on grass composition around permanent water points along a pipeline and around a traditional hand‐dug well in an important grazing area in central northern Namibia. Grass species abundance and selected environmental variables sampled along transects radiating out from these water points were analysed using Canonical Correspondence Analysis (CCA). Significant grazing‐induced changes, manifested by palatable perennial grasses being replaced by less palatable annual grasses, were identified around water points along the pipeline. There annual grasses Schmidtia kalihariensis and Aristida stipioides dominate the vegetation as far as 5 km from the water points. No significant grazing‐induced changes in grass composition were observed around the hand‐dug well. Private ownership leading to stronger control of access to traditional wells compared to the open access water points along the pipeline seems to be a key factor preventing overutilisation of grazing resources around the former. Copyright © 2007 John Wiley & Sons, Ltd.
All‐fiber mode‐multiplexed transmission of two channels in a single step‐index multimode fiber
Authors: Schmauss Bernhard
Published: July 2007

Mode multiplexing, a method for transmitting two signals in one fiber without time‐ or wavelength multiplexing, is presented in theoretically and experimentally. It is shown that two mode‐coded channels can be launched and separated using optical directional couplers with enhanced mode selectivity combined with a simple signal processing unit. © 1993 John Wiley & sons, Inc.
Thin pseudochiral layers: Approximate boundary conditions and potential applications
Authors: Tretyakov Sergei A.
Published: July 2007

Here we study electromagnetic properties of thin layers of novel pseudochiral synthetic materials, described by bianisotropic constitutive relations. Approximate boundary conditions are given to model plane layers and to simplify electromagnetic analysis. Properties of waves in a strip line on a two‐layer ferrite‐pseudochiral substrate are studied and examples of prospective uses of pseudochiral composites are suggested. © 1993 John Wiley & sons, Inc.
Effects of nonideal optical‐fiber equalization
Authors: Ibrahim Magdy M. , Ibrahim A. M.
Published: July 2007

Effects of nonideal‐fiber equalization are analyzed in terms of a sensitivity parameter ζ, defined as

where αout is the RMS width of the output pulse and θ is a parameter that represents the deviation of the actual transfer function from the ideal one. The dependence of that parameter on the width of the predistorted signal is given, along with its dependence on the mismatch factor θ. © 1993 John Wiley & sons, Inc.
Simplified design theory for a circular microstrip patch antenna
Authors: Roy Jibendu Sekhar , Jecko Bernard
Published: July 2007

An accurate and simple design procedure for a circular microstrip patch antenna to operate in the dominant mode is obtained, for which it is not necessary to compute the conventional design theory, involving the Bessel function. The design equations presented in this article provide for the design of a circular microstrip antenna, in a direct way, for specified resonant resistance and gain in the desired frequency. From this design theory, it is found that the effective gain of a circular microstrip antenna in the dominant mode can be evaluated measuring resonant resistance only. This is also verified experimentally. © 1993 John Wiley & sons, Inc.
Phase modulation in a liquid‐crystal TV based joint transform correlator
Authors: Gregory Don A. , Kirsch J. C. , Tanone Aris , Yin S. , Andres P. , Yu Francis T. S. , Tam Eddy C.
Published: July 2007

A phase‐encoded object has been modeled as the input to a joint transform correlator. The joint transform power spectrum is modeled as a binary phase object to calculate the correlation output. The results have been experimentally verified using a liquid‐crystal television operating in the phase modulation mode.
Analyzing the radiated characteristics of a two‐layered chirostrip dipole antenna using the dyadic green's function
Authors: Yin Wenyan , Wang Wenbin
Published: July 2007

A formulation of the dyadic Green's function for a two‐layered chirostrip is presented using the method of scattering superposition, and an expression of the radiated field of a horizontal dipole antenna printed on a grounded chiral slab is derived. The effects of a chiral superstrate on the radiation pattern are analyzed. © 1993 John Wiley & sons, Inc.
The analysis of the hybrid distributed amplifier
Authors: Gao Huai , Wu Wen
Published: July 2007

In this article, in accordance with the concept of equal voltage transmission, an analysis of the hybrid line sections in the drain circuit of a distributed amplifier is presented. © 1993 John Wiley & sons, Inc.
An experimental investigation into microstrip antenna elements suitable for mobilesat applications
Authors: Jellett S. T. , Bialkowski M. E. , Dimitrios A. P.
Published: July 2007

An experimental investigation atL‐band frequencies was performed on single patch and electromagnetically coupled microstrip antennas. The aim was to find an antenna array element suitable for mobile satellite communications. Various results and field pattern measurements were taken for different patch sizes and antenna configurations. © 1993 John Wiley & sons, Inc.
A novel RF reference source using subharmonically locked synchronous oscillation
Authors: Lam Vincent M. T. , Yip Peter C. L.
Published: July 2007

The design and implementation of a stable reference source at 258 MHz using subharmonically locked oscillation is described. The stability of the oscillator is achieved by locking a synchronous oscillator (SO) to a stable crystal oscillator, the stability of which is to be transferred to the SO, oscillating at a subharmonic frequency of the required output frequency. The reference source is a low‐voltage (1.2 V) and low‐current (1.18 mA) consumption design. This type of reference source is potentially very useful in fixed frequency mobile receivers and transmitters where crystal referred frequency stability, supply voltage, current consumption, and size are major design constraints. © 1993 John Wiley & sons, Inc.
A further development on uniform asymptotic expansions
Authors: Vaudon P. , Jecko B.
Published: July 2007

By exhibiting the development of the Pauli‐Clemmow method in a new manner, it is shown that the two uniform asymptotic expansions commonly used are different. Next it is shown that an infinity of different uniform asymptotic expansions can be constructed for each type of development. This allows us to set the Kouyoumjian and Pathak formulation on a rigorous basis. © 1993 John Wiley & sons, Inc.
A new type TEM cell with a sliding cross as inner conductor
Authors: Lin Weigan
Published: July 2007

Riblet's rectangular line with off‐center strip inner conductor is changed into one with a vertically sliding symmetrical cross as an inner conductor. © 1993 John Wiley & sons, Inc.
An inexpensive microwave distance measuring system
Authors: Noon David A. , Bialkowski Marek E.
Published: July 2007

An inexpensive system that accurately measures ranges of the order of meters, with the resolution of centimeters, is described. The synthesized pulse and phase counting methods, based on coherent transmission and quadrature detection, are discussed. Suitable calibration schemes to obtain distance measurement accuracies better than 99% are described. © 1993 John Wiley & sons, Inc.
Kerr bistability in optical fiber loop resonators with a 3 × 3 fiber coupler
Authors: Ja Y. H.
Published: July 2007

A theoretical study of bistability caused by the Kerr effect in two types of optical fiber loop resonators connected to a 3 × 3 coupler is carried out. The dependence of the bistability on various parameters of the fiber and the coupler is investigated and presented as graphs. The bistability offers the possibility of using these fiber loop resonators as optical logic gates, memories, switches, and differential amplifiers. © 1993 John Wiley & sons, Inc.
Complex target polarimetric modelization and measurement
Authors: Desclos L.
Published: July 2007

A study of all possible polarimetric behavior modelization is presented. The aim of this work is also to present a model for a complex target seen as an assembly of saddle points, when the target's dimensions are greater than few wavelengths. From these assumptions the use of asymptotic techniques leads to a list of saddle points which are capable of precise description of complex targets. © 1993 John Wiley & sons, Inc.
Quasistatic analysis of a pair of skewed transmission lines in multilayered dielectric media for mmic applications
Authors: Carpentier J. F. , Pribetich P. , Kennis P.
Published: July 2007

The capacitive coupling between two microstrip lines crossing diagonally above a ground plane in a multilayered dielectric substrate is analyzed through a quasistatic approach based on the space‐domain integral equation method. The typical evolutions of the normalized lumped excessive capacitances for nonorthogonal crossover configurations are presented. © 1993 John Wiley & sons, Inc.
Attenuation properties of normal modes in coated circular waveguides with imperfectly conducting walls
Authors: Huang Zhixun , Zeng Cheng
Published: July 2007

A new analytic characteristic equation is presented and applied to the analysis of attenuation properties of normal modes in coated circular waveguides including conductor loss. Approximate and numerical methods are employed to accomplish the solution to the new equation, resulting in some useful approximate formulas for calculations of modal attenuations. These formulas are applicable to the analysis and design of the coated circular waveguide including conductor loss because of their good agreement with the numerical results obtained by the computer. © 1993 John Wiley & sons, Inc.
The propagation characteristics of nonlinear guided waves along a nonlinear waveguide bounded by two identical self‐focusing media
Authors: Chang Wen‐Ching , Liu Shuh‐Fang , Wang Way‐Seen
Published: July 2007

The propagation phenomena of nonlinear guided waves along a nonlinear waveguide bounded by two identical self‐focusing media are studied numerically. Both TE0 and TE1 guided waves are investigated. It is indicated that the derivative of the guided‐wave power flow with respect to the guided‐wave effective index can be a criterion for the stability of nonlinear guided waves under consideration. © 1993 John Wiley & sons, Inc.
Analysis of double‐step discontinuity in a rectangular waveguide using a TEX‐TMXfield expansion
Authors: Gentili G. G. , Melloni A. , Macchiarella G. , Politi M.
Published: July 2007

The analysis of double‐step discontinuity in a rectangular waveguide is presented using a TEx‐TMxfield‐expansion and mode‐matching technique. The procedure keeps the advantages of TExexpansion (fewer modes with respect to TE‐TM) and still holds when TExfails because of the excitation of the Exfield component. © 1993 John Wiley & sons, Inc.