bluuebunny/crossref_metadata_2025 huggingface dataset:
RECURSIVE BAIRE CLASSIFICATION AND SPEEDABLE FUNCTIONS
Authors: Calude Cristian , Istrate Gabriel , Zimand Marius
Published: May 2007

Using recursive variants of Baire notions of nowhere dense and meagre sets we study the topological size of speedable and infinitely often speedable functions in a machine‐independent framework. We show that the set of speedable functions is not “small” whereas the set of infinitely often speedable functions is “large”. In this way we offer partial answers to a question in [4].
TOPOLOGICAL FRAMEWORK FOR FINITE INJURY
Authors: Kontostathis Kyriakos
Published: May 2007

We formulate an abstract version of the finite injury method in the form of the Baire category theorem. The theorem has the following corollaries: The Friedberg‐Muchnik pair of recursively enumerable degrees, the Sacks splitting theorem, the existence of a minimal degree below 0′ and the Shoenfield jump theorem.
THE FUNDAMENTAL THEOREM OF ULTRAPRODUCT IN PAVELKA'S LOGIC
Authors: Ying Mingsheng
Published: May 2007

In [This Zeitschrift 25 (1979), 45‐52, 119‐134, 447‐464], Pavelka systematically discussed propositional calculi with values in enriched residuated lattices and developed a general framework for approximate reasoning. In the first part of this paper we introduce the concept of generalized quantifiers into Pavelka's logic and establish the fundamental theorem of ultraproduct in first order Pavelka's logic with generalized quantifiers. In the second part of this paper we show that the fundamental theorem of ultraproduct in first order Pavelka's logic is preserved under some direct product of lattices of truth values.
ON THE INADEQUACY OF THE RELATIONAL SEMANTIC FOR THE “UNTIL” OPERATOR
Authors: Bellissima Fabio , Ciupi Alessandra
Published: May 2007

Modal logics with the binary operator Until are considered. It is shown that there exists a continuum of consistent U‐logics without Kripke frames, and that each U‐logic whose class of order does not have the finite frame property.
REPRESENTATION OF POSETS
Authors: Cheng Yungchen , Kemp Paula
Published: May 2007

In this paper we give new criterions for left distributive posets to have neatest representations. We also illustrate a construction that would embed left distributive posets into representable semilattices.
LA RECONSTRUCTION DES TOURNOIS SANS DIAMANT
Authors: Gnanvo Cyprien , Ille Pierre
Published: May 2007

We prove that if T is a tournament of order n > 6 in which any 4‐sub‐tournament is hamiltonian or transitive, then T is reconstructible in the sense of Ulam.
SOME RAMSEY THEORY IN BOOLEAN ALGEBRA FOR COMPLEXITY CLASSES
Authors: McColm Gregory L.
Published: May 2007

It is known that for two given countable sets of unary relations A and B on ω there exists an infinite set H ⫅ ω on which A and B are the same. This result can be used to generate counterexamples in expressibility theory. We examine the sharpness of this result.
A GAME‐THEORETIC PROOF OF ANALYTIC RAMSEY THEOREM
Authors: Tanaka Kazuyuki
Published: May 2007

We give a simple game‐theoretic proof of Silver's theorem that every analytic set is Ramsey. A set P of subsets of ω is called Ramsey if there exists an infinite set H such that either all infinite subsets of H are in P or all out of P. Our proof clarifies a strong connection between the Ramsey property of partitions and the determinacy of infinite games.
REDUCIBILITY IN SOME CATEGORIES OF PARTIAL RECURSIVE OPERATORS
Authors: Bianchini Caterina , Sorbi Andrea
Published: May 2007

We consider two categories with one object, namely the set of all partial functions of one variable from the set of natural numbers into itself; the morphisms are the partial recursive operators in one case, and certain continuous partial mappings in the other case. We show that these categories are recursion categories and we characterize the domains and the complete domains. Some observations are made on a notion of reducibility obtained by using the total morphisms of these categories, and, subsequently, the general recursive operators.
ON THE TRANSITIVE HULL OF A κ‐NARROW RELATION
Authors: Diener Karl‐Heinz , Diener K.‐H.
Published: May 2007

We will prove in Zermelo‐Fraenkel set theory without axiom of choice that the transitive hull R* of a relation R is not much “bigger” than R itself. As a measure for the size of a relation we introduce the notion of κ+‐narrowness using surjective Hartogs numbers rather than the usul injective Hartogs values. The main theorem of this paper states that the transitive hull of a κ+‐narrow relation is κ+‐narrow. As an immediate corollary we obtain that, for every infinite cardinal κ, the class HCκ of all κ‐hereditary sets is a set with von Neumann rank ϱ(HCκ) ≤ κ+. Moreover, ϱ(HCκ) = κ+ if and only if κ is singular, otherwise ϱ(HCκ) = κ. The statements of the corollary are well known in the presence of the axiom of choice (AC). To prove them without AC ‐ as carried through here ‐ is, however, much harder. A special case of the corollary (κ = ω1, i.e., the class HCω1 of all hereditarily countable sets) has been treated independently by T. JECH.
BOUNDS IN THE TURING REDUCIBILITY OF FUNCTIONS
Authors: Habart Karol , Habart K.
Published: May 2007

A hierarchy of functions with respect to their role as bounds in the Turing reducibility of functions is introduced and studied. This hierarchy leads to a certain notion of incompressibility of sets which is also investigated.
RESTRICTION RESPECTUEUSE ET RECONSTRUCTION DES CHAINES ET DES RELATIONS INFINITES
Authors: Hagendorf Jean Guillaume , Hagendorf J. G.
Published: May 2007

We show a faithful restriction theorem among infinite chains which implies a reconstructibility conjecture of Halin. This incite us to study the reconstructibility in the sense of Fraïssé and to prove it for orders of cardinality infinite or ≥ 3 and for multirelations of cardinality infinite or ≥ 7, what improves the theory obtained by G. Lopez in the finite case. For this work we had to study the infinite classes of difference which have to be a linear order of type ω, ω* or ω* + ω; this complete the theory made by G. Lopez for the finite case ([13]). We show also Ulam‐reconstructibility for linear orders which have a fixed point.
TOPOS BASED SEMANTIC FOR CONSTRUCTIVE LOGIC WITH STRONG NEGATION
Authors: Klunder Barbara , Klunder B.
Published: May 2007

The aim of the paper is to show that topoi are useful in the categorial analysis of the constructive logic with strong negation. In any topos ϵ we can distinguish an object Λ and its truth‐arrows such that sets ϵ(A, Λ) (for any object A) have a Nelson algebra structure. The object Λ is defined by the categorial counterpart of the algebraic FIDEL‐VAKARELOV construction. Then it is possible to define the universal quantifier morphism which permits us to make the first order predicate calculus. The completeness theorem is proved using the Kripke‐type semantic defined by THOMASON.
PROVABILITY LOGIC IN THE GENTZEN FORMULATION OF ARITHMETIC
Authors: Gentilini Paolo , Gentilini P.
Published: May 2007

In this paper are studied the properties of the proofs in PRA of provability logic sentences, i.e. of formulas which are Boolean combinations of formulas of the form PIPRA(h), where h is the Gödel‐number of a sentence in PRA. The main result is a Normal Form Theorem on the proof‐trees of provability logic sequents, which states that it is possible to split the proof into an arithmetical part, which contains only atomic formulas and has an essentially intuitionistic character, and into a logical part, which is merely instrumental. Moreover, the induction rules which occur in the arithmetical part are implicit. Some applications of the Normal Form Theorem are shown in order to obtain some syntactical results on the PRA‐completeness of modal logic. In particular a completeness theorem for Boolean combinations of modalities is given.
FLAGG AND FRIEDMAN'S TRANSLATION IS NOT FAITHFUL
Authors: Inoué Takao , Inoué T.
Published: May 2007

We prove that Flagg and Friedman's translation from epistemic to intuitionistic predicate (propositional) logics is not faithful.
A Simplified Proof of the 0–1 Law for Existential Second‐Order Ackermann Sentences
Authors: Lacoste Thierry
Published: May 2007

Recently we gave a finitistic proof of the 0–1 law for ∑11 (Ackermann) sentences, which relied as much as possible on the original argument of Kolaitis and Vardi. Here we present another version of our proof which, on the contrary, is self‐contained. Finitism allows us to use the beautiful probabilistic argument of Kolaitis and Vardi in a simple and intuitive way. Consequently, we obtain a shorter proof.
Comparing the Power of Games on Graphs
Authors: Fagin Ronald
Published: May 2007

The descriptive complexity of a problem is the complexity of describing the problem in some logical formalism. One of the few techniques for proving separation results in descriptive complexity is to make use of games on graphs played between two players, called the spoiler and the duplicator. There are two types of these games, which differ in the order in which the spoiler and duplicator make various moves. In one of these games, the rules seem to be tilted towards favoring the duplicator. These seemingly more favorable rules make it easier to prove separation results, since separation results are proven by showing that the duplicator has a winning strategy. In this paper, the relationship between these games is investigated. It is shown that in one sense, the two games are equivalent. Specifically, each family of graphs used in one game (the game with the seemingly more favorable rules for the duplicator) to prove a separation result can in principle be used in the other game to prove the same result. This answers an open question of Ajtai and the author from 1989. It is also shown that in another sense, the games are not equivalent, in that there are situations where the spoiler requires strictly more resources to win one game than the other game. This makes formal the informal statement that one game is easier for the duplicator to win.
Experimental investigation of layer displacements for a singly‐fed circularly polarized stacked patch antenna
Authors: Chung Kwok L. , Mohan Ananda S.
Published: May 2007

This article presents experimental investigation on the effect of layer displacements for an X‐band circularly polarized patch antenna. Experimental results demonstrate that such antenna makes use of high‐low‐low dielectric materials combination has tolerant characteristics not just on the impedance bandwidth but also the CP bandwidth to withstand layer displacements. Based on the measured bandwidths, displacement limits are located as 0.067λo for the entire x‐y plane. Also, gain variations are found to be insignificant. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2047–2050, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22562
Simple CAD formulas of silicon based RFIC components by synthetic asymptote with insight and few arbitrary constants
Authors: Tang Wanchun , Jiang Baozheng , Chen Xuemei , Chow Y. Leonard
Published: May 2007

This article derives simple computer‐aided design (CAD) formulas of the components of Silicon, based radio frequency integrated circuits (Si‐RFIC) by synthetic asymptote. The formulas include, those for microstripline, patch capacitor, and spiral inductor. With “bootstrapping”, one can obtain, CAD formulas of the components from simple to more complicated and practical. These formulas are, simple, accurate, with good physical insights, and few arbitrary constants. Compared with numerical, methods, the average errors are less than 2%. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1917–1921, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22568
Omnidirectional stop band by using composite two‐dimensionally artificial crystal
Authors: Hwang Ruey Bing , Pu Ta Chun
Published: May 2007

We present here a study of the wave propagation in a two‐dimensionally (2D) periodic structure. The scattering of a plane wave by a 2D periodic structure is analyzed as a multilayer boundary‐value problem. Specific examples are given to show quantitatively the stopband behaviors; in particular, a composite structure with different lattice patterns in cascade is shown to achieve the broad and omnidirection behavior of stop band. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1914–1917, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22569
A closed‐form expression for the resonant frequency of rectangular microstrip antennas
Authors: Akdagli Ali
Published: May 2007

A new and accurate expression for the edge extension in accurately predicting the resonant frequency of electrically thin and thick rectangular microstrip antennas is presented. First, a closed‐form model for the edge extension is constructed by utilizing a differential evolution algorithm, the resonant frequency of rectangular microstrip antennas is then calculated by means of this edge extension expression. The calculations were carried out on 46 antennas with a range of different dimensions built on various substrates. The resonant frequency results presented in this letter show the better agreement with the experimental results as compared with those reported by the several researchers. A comparison between calculated and experimental resonant frequencies demonstrates that the edge extension model provides less than 0.7% errors on average. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1848–1852, 2007; Published online in Wiley Inter‐Science (www.interscience.wiley.com). DOI 10.1002/mop.22572
Thermally poled twin‐hole fibers with tungsten electrodes
Authors: Wu Gang , Zhou Li , Wang Ziyu
Published: May 2007

A twin‐hole fiber with two 1‐m‐long tungsten wires inserted as its internal electrode was made successfully. This is the longest internal‐electrode fiber ever achieved from metal wire insertion technology. The propagation loss of this kind of fiber is only 0.47 dB/m at 1 550 nm. No additional loss is measured after the tungsten wire has been inserted. The fiber is thermally poled at 3 kV voltage, inducing a permanent electro‐optic coefficient of 0.06 pm/V. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2010–2012, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22578
Multilayer cross‐coupled resonator bandpass filters fabricated on low temperature cofired ceramic substrates
Authors: Hsieh Ming‐Liang , Huang Tsung‐Hui , Chen Lih‐Shan , Sun Chian‐Hao , Wang Shuming , Houng Mau‐Phon , Fu Shen‐Li
Published: May 2007

Multilayer cross‐coupled open‐loop resonator bandpass filters have been developed on low temperature cofired ceramic substrates. The center frequency of the designed bandpass filter is at 5.2 GHz and the fractional bandwidth is 4%. The measured center frequency is 5.2 GHz, passband insertion loss is 1.46 dB, and fraction bandwidth is 2%. The measured frequency responses of the fabricated bandpass filters are in agreement with simulated results. By constructing multilayer structure, a compact bandpass filter can be realized. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1977–1979, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22580
Broadband RF grounding capacitor design for low power CMOS matrix distributed amplifier
Authors: Lee Sung‐Huang , Li Chin‐Lung , Juang Ying‐Zong , Chiou Hwann‐Kaeo
Published: May 2007

Four broadband RF grounding capacitor array are designed, implemented, and compared with different maximum path loss and parasitic for CMOS broadband amplifiers. According to the measured results, the most popular RF grounding capacitor array with simple parallel connected topology is not suitable for broadband circuits because of its loss at high frequency. The other three proposed topologies with reduction of path losses and parasitic have better broadband characteristics than the simple parallel connected type. To understand the effect of RF grounding capacitor array in broadband circuits, the type II capacitor array is adopted in the experiment circuit, a matrix distributed amplifier, and the measured result shows well‐estimation could be obtained with the consideration of grounding capacitors. This 2 × 2 matrix amplifier achieves a better gain‐bandwidth product versus power consumption among recent CMOS broadband amplifier designs. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1911–1914, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22583
Planar slot‐array antenna fed by an oversized quasi‐TEM waveguide
Authors: Valero‐Nogueira A. , Alfonso E. , Herranz J.I. , Baquero M.
Published: May 2007

We propose a novel planar slot‐array antenna fed by a new guiding structure which forces a quasi‐TEM mode within an oversized rectangular waveguide. To achieve a quasi‐TEM mode throughout the waveguide a hard surface is placed on the bottom surface of the waveguide while the radiating slots are at the upper face. The waveguide is able to propagate invariant linear phase‐fronts along the axial direction which makes it attractive for steerable array antennas. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1875–1877, 2007; Published online in Wiley Inter‐Science (www.interscience.wiley.com). DOI 10.1002/mop.22586
A novel four‐stages double‐layered dielectric waveguide bandpass filter in LTCC
Authors: Liang Fei , Wu Zhipeng , Lu Wenzhong , Zhou Dongxiang
Published: May 2007

This study presents a novel four‐stage double‐layered waveguide bandpass filter and its simulation method. The longitudinal size of the waveguide filters is reduced by 50% due to the application of double‐layered structure. The four‐stage double‐layered bandpass filter with a 8.8 mm length, 6.2 mm width, and 1.6 mm height is manufactured by LTCC. It has a center frequency of 5.21 GHz, bandwidth of 300 MHz, pass‐band ripple of 0.1 dB, and insertion loss of 0.8 dB, which shows miniaturization, low insertion losses and meets the demand of next generation of WLAN system. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1837–1840, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22587
Novel design of printed monopole antenna for WiMAX application
Authors: Chen Wen‐Shan , Chang Yu‐Chen , Chang Fa‐Shian
Published: May 2007

In this article, a novel design of printed coplanar waveguide‐fed monopole antenna is proposed for triple‐band WiMAX applications. At first, we investigate the printed dual‐band monopole antenna for dual‐band operation with two bands of 2.37–3.64 GHz and 5.2–6 GHz. Since the lower band (2.5–2.7 GHz) is quite near the middle band (3.3–3.8 GHz) band of WiMAX resulted in large coupling effect or interference between these two bands; we need band‐rejected function to suppress the undesired frequency‐bands. Then, using the two narrow strips etched from printed dual‐band monopole antenna, an antenna design of WiMAX is achieved. The low cost, easy manufacture, good impedance match, good radiation patterns of the proposed antenna are also investigated in this article. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1806–1809, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22589
Internal GSM/DCS patch antenna mounted above the system ground plane of the PDA phone
Authors: Wong Kin‐Lu , Chang Chih‐Hua , Row Jeen‐Sheen
Published: May 2007

This paper presents an internal dual‐band patch antenna to be mounted above the system ground plane of the PDA (personal digital assistant) phone for GSM/DCS operation. The antenna is supported by conducting pins (5 mm long in this study) and mounted above the system ground plane of the PDA phone. In this case, the antenna does not directly occupy the system ground plane, and a usable space between the antenna ground portion and the system ground plane is provided for accommodating associated conducting elements or electronic components of the PDA phone. A design example is demonstrated, and obtained results are presented and discussed. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2002–2006, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22593
Transmission line delay‐based radio frequency identification (RFID) tag
Authors: Vemagiri Jeevan , Chamarti Aravind , Agarwal Mangilal , Varahramyan Kody
Published: May 2007

This paper presents the design, simulation, fabrication, and characterization of a transmission delay line‐based RFID tag. The ID generating circuit is designed based on the transmission delay line concept. A compact, inset‐fed triangular patch antenna resonant at 915 MHz frequency is developed for integration with the tag application. The layout of the tag has been realized using conventional photolithography. Tags with a 5‐ and 10‐ns delay ID generation circuits have been tested using input signals of 10‐ns width. An OOK (On‐Off Keying) modulation technique is employed for characterization of the tag. The received output consists of delayed signal from the tag added to the direct signal from the transmitter. Transmission delay line‐based RFID technology can be exploited for low‐end commercial applications that has a large market. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1900–1904, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22599
A novel radiation boundary condition for finite‐element method
Authors: Liu Jianguo , Liu Qing Huo
Published: May 2007

This paper presents a novel radiation boundary condition (RBC) with the spectral integral method (SIM) to truncate the computational domain in the finite‐element method (FEM). Because of the spectral accuracy of the SIM, the sampling density on the radiation boundary requires less than four points per wavelength to achieve a high accuracy (1%). As a result, the introduction of the SIM as an RBC actually can decrease the total number of unknowns in the system equation. Numerical results illustrate the usefulness of this novel RBC for both homogeneous and inhomogeneous objects. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1995–2002, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22608
Dynamic dispersing technique for PR coating process in planar lightwave circuit fabrication
Authors: Hong Pua Chang , Harun Sulaiman Wadi , Yi Chong Wu , Jayapalan Kanesh Kumar , Ahmad Harith
Published: May 2007

A new dynamic dispersing technique (DDT) is proposed and demonstrated to improve the photoresist (PR) coating process in planar lightwave circuit (PLC) fabrication. In this technique, the PR is dispensed during the wafer's spin cycle on the spin coater instead of the conventional static dispensing before spinning. In comparison to the conventional static dispersing technique (SDT), DDT has significantly improved several properties of the PR layer including its thinning behavior, coating uniformity, and PR amount. Using DDT, the PR thickness averagely reduces by ∼0.2 μm. The radial uniformity of the PR from the centre is also improved from the average difference of 0.28 μm in SDT to 0.14 μm in DDT. Furthermore, the PR amount required for the coating process is reduced from 3.00 ml (SDT) to 0.25 ml (DDT). Two different DDTs are also compared in this paper including the application of PR during the spin coater's acceleration step (1st DDT) and the application of PR during the spin coater's constant speed (2nd DDT). © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1993–1995, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22609
High‐purity millimeter‐wave signal photonic generation
Authors: Wang Tianliang , Chen Minghua , Chen Hongwei , Xie Shizhong
Published: May 2007

A simple method of optical generation millimeter‐wave signal employing optical phase modulator and band‐elimination filter is proposed. This simple approach is capable of generating millimeter wave signal of quadrupled or sextuple microwave source frequency with extremely high spectral purity. Millimeter‐wave signal 26 GHz (quadrupled fundamental) or 39 GHz (sextuple fundamental) is obtained respectively using different system chromatic dispersion when the microwave driver signal is at 6.5 GHz. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1894–1897, 2007; Published online in Wiley Inter‐Science (www.interscience.wiley.com). DOI 10.1002/mop.22615
A novel dual‐band patch antenna for Zigbee system
Authors: Lee Jung N. , Park Jong K. , Choi H. , Kim Jin S.
Published: May 2007

In this article, a novel dual‐band patch antenna having a chair‐shaped slot is designed, fabricated, and measured for Zigbee system. The proposed antenna is designed to operate from 868 to 928 MHz (lower‐frequency band) and 2.45 GHz (upper‐frequency band). The lower‐frequency band (868–928 MHz) can be controlled by adjusting the length of a chair‐shaped slot and the upper‐frequency band (2.45 GHz) can be controlled by the size of the rectangular patch. Details of the proposed antenna design and the measured results are presented and discussed. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1864–1867, 2007; Published online in Wiley Inter‐Science (www.interscience.wiley.com). DOI 10.1002/mop.22616
On a quality factor of whispering gallery mode dielectric resonators in a form of cone
Authors: Cherpak Nickolay T. , Bunyaev Sergey A. , Barannik Alexander A.
Published: May 2007

The whispering gallery mode (WGM) resonators in a form of cone demonstrate that a quality factor Q in microwave range decreases monotonously with increase of angle α between a cone axis and generatrix. Both a form of the resonator made of Teflon and coupling between the resonator and input/output dielectric waveguides are analogous to them in the optic microcavity, where it was supposed that isolating mode from the disk perimeter resulted in Q increase. However the effect of increase of Q with α is not observed in microwave range. The cone resonators excited on WGM promise to become useful for microwave and millimeter‐wave characterization of high‐Tc superconducting films. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1987–1989, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22625
A generalized iterative multiregion technique to solve the nonhomogeneous electromagnetic wave equation
Authors: Adriano Ricardo L. S. , Vasconcelos João A. , Rego Cássio G. do , Silva Élson J.
Published: May 2007

This article presents a generalization of the iterative multiregion technique applied in solving the nonhomogeneous wave equation. A formal proof that this procedure converges independently of the numerical method applied to each sub‐domain and an error estimate are presented by applying the iterative method directly on the electromagnetic governing equations. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1921–1926, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22629
Cross‐coupled Hilbert spiral resonator for bandpass filter design
Authors: Liu Ji‐Chyun , Lu Po‐Chiang , Chien Chi‐Hsun , Chang Jun‐Mao , Chen Jong‐Yih , Lin Horng‐Jyh
Published: May 2007

The modified cross‐coupled spiral resonators with Hilbert configuration are introduced for a large coupling coefficient in this article. For comparison, the conventional cross‐coupled spiral resonators are fabricated and measured herein. To obtain low insertion loss (−0.27 dB), high out‐of‐band rejection level (−19.5 dB) and wider FBW (50.9%), the filter of simplified CCSR‐H is proposed. Results included surface current distribution and frequency responses are presented and discussed. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1890–1894, 2007; Published online in Wiley Inter‐Science (www.interscience.wiley.com). DOI 10.1002/mop.22630
Analysis of L‐strip proximity fed rectangular microstrip antenna for mobile base station
Authors: Meshram Manoj Kumar
Published: May 2007

A wide‐band L‐strip proximity fed rectangular microstrip antenna is proposed and investigated both theoretically and experimentally. The radiating patch is located about 0.1λ0(16.5 mm) above the ground plane. The broadband characteristic of antenna is achieved by employing a thick substrate (0.1λ0). Numerical results for the input impedance, VSWR, and co‐ and cross‐polar radiation pattern are presented and compared with the measured results. Good agreement is obtained between computed and measured results. The effects of the geometric parameters of the L‐strip like length of the vertical and horizontal portion of the strip are investigated. It is found that the antenna attains 48.36% impedance bandwidth (SWR ≤ 2) (theoretically) and 56.67% (experimentally) for optimized antenna design. The H‐plane cross‐polarization level is quite high (−16 dB) especially at (computed θ ≈ 60°, and measured θ ≈ 40°) whereas the E‐plane cross‐polarization level is very low. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1817–1824, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22634
Optimising reaction performance in the pharmaceutical industry by monitoring with NMR
Authors: Bernstein Michael A. , Štefinović Marijan , Sleigh Chris J.
Published: May 2007

Quality assurance and process understanding are assuming increasing importance in the production of Active Pharmaceutical Ingredients (APIs). NMR has the potential to report on physical processes, quantities, structures, and speciation as chemical reactions progress. Following the progression of chemical reactions by placing the sample in an NMR tube, one can perform a large number of useful studies that provide chemical and mechanistic insight. But this simple approach can have limitations, and we have therefore constructed an apparatus comprising a laboratory reactor coupled with an NMR flow cell. The reactor duplicates the exact reaction conditions that will apply with large‐scale production. This reaction mixture is sampled and pumped to a high‐resolution NMR flow cell where the spectrum is recorded through the course of the reaction. We demonstrate the utility of reaction monitoring using NMR both for simple cases where tubes can be used, and describe the design of the on‐flow apparatus and highlight its utility with an example. Copyright © 2007 John Wiley & Sons, Ltd.
Chiral recognition of the Schiff bases by NMR spectroscopy in the presence of a chiral dirhodium complex. Deuterium isotope effect on 13C chemical shift of the optically active Schiff bases and their dirhodium adducts
Authors: Rozwadowski Z.
Published: May 2007

The dirhodium method has been successfully applied in chiral recognition of the optically active Schiff bases, derivatives of ortho‐hydroxyaldehydes existing in the NH‐form. or at tautomeric equilibrium. The position of the equilibrium of Schiff bases as well as their adducts has been established on the basis of measurements of deuterium isotope effects on 13C chemical shifts. The presence of the proton transfer equilibrium or NH‐tautomer has promoted the adduct formation. At the equilibrium state, formation of the adducts has shifted the proton transfer equilibrium towards the NH‐form. The binding site was the oxygen atom of the proton donor group. Copyright © 2007 John Wiley & Sons, Ltd.
Homonuclear long‐range correlation spectra from HMBC experiments by covariance processing
Authors: Schoefberger Wolfgang , Smrečki Vilko , Vikić‐Topić Dražen , Müller Norbert
Published: May 2007

We present a new application of covariance nuclear magnetic resonance processing based on 1H13C‐HMBC experiments which provides an effective way for establishing indirect 1H1H and 13C13C nuclear spin connectivity at natural isotope abundance. The method, which identifies correlated spin networks in terms of covariance between one‐dimensional traces from a single decoupled HMBC experiment, derives 13C13C as well as 1H1H spin connectivity maps from the two‐dimensional frequency domain heteronuclear long‐range correlation data matrix. The potential and limitations of this novel covariance NMR application are demonstrated on two compounds: eugenyl‐β‐D‐glucopyranoside and an emodin‐derivative. Copyright © 2007 John Wiley & Sons, Ltd.
In vitro comparison of the biological effects of three transfection methods for magnetically labeling mouse embryonic stem cells with ferumoxides
Authors: Suzuki Yoriyasu , Zhang Sally , Kundu Pratima , Yeung Alan C. , Robbins Robert C. , Yang Phillip C.
Published: May 2007

In vivo MRI of stem cells (SCs) is an emerging application to evaluate the role of cell therapy in restoring the injured myocardium. The high spatial and temporal resolution combined with iron‐oxide‐based intracellular labeling techniques will provide a sensitive, noninvasive, dual imaging modality for both cells and myocardium. In order to facilitate this novel imaging approach, much effort has been directed towards developing efficient transfection methods. While techniques utilizing poly‐L‐lysine (PLL), protamine sulfate (PS), and electroporation (ELP) have been proposed, the fundamental biological effects of these methods on mouse embryonic SCs (mESC) have not been investigated systematically. In this study a longitudinal in vitro evaluation of cellular viability, apoptosis, proliferation, and cardiac differentiation of magnetically labeled mESC was conducted. No significant difference was seen in these biological parameters among the three transfection methods. However, cardiac differentiation was most attenuated by ELP, and iron uptake was most effective by PS. Magn Reson Med 57:1173–1179, 2007. © 2007 Wiley‐Liss, Inc.
Short data‐acquisition times improve projection images of lung tissue
Authors: Kuethe Dean O. , Adolphi Natalie L. , Fukushima Eiichi
Published: May 2007

MR images of laboratory rat lungs that resolve the thin membranes that separate lung lobes are presented. It appears that the capabilities of in vivo small‐animal pulmonary MRI may rival those of in vivo small‐animal X‐ray CT. Free induction decay (FID)‐projection imaging was employed with particular attention to the choice of acquisition time. For a given nominal resolution, one obtains optimal point discrimination when the acquisition timeTacqnormalized by the signal decay time constantTis approximately 0.8–0.9, although a better signal‐to‐noise ratio (SNR) is obtained when this quotient is 1.6. Currently available equipment should be able to even exceed the results presented herein. Magn Reson Med 57:1058–1064, 2007. © 2007 Wiley‐Liss, Inc.
In vivo differentiation of N‐acetyl aspartyl glutamate from N‐acetyl aspartate at 3 Tesla
Authors: Edden Richard A.E. , Pomper Martin G. , Barker Peter B.
Published: May 2007

A method is described that allows the in vivo differentiation of N‐acetyl aspartate (NAA) from N‐acetyl aspartyl glutamate (NAAG) by in vivo MR spectroscopy (MRS) at 3 Tesla (3T). The method, which is based on MEGA‐point‐resolved spectroscopy (PRESS) editing, selectively targets the aspartyl spin system of one species while deliberately removing the other species from the spectrum. This allows quantitative measurements of NAA and NAAG without the need for fitting of unresolved peaks. White matter concentrations of NAA (6.7 ± 0.3 mM) and NAAG (2.2 ± 0.3 mM) were measured in 10 healthy volunteers to demonstrate the method. Magn Reson Med 57:977–982, 2007. © 2007 Wiley‐Liss, Inc.
Undersampled radial MRI with multiple coils. Iterative image reconstruction using a total variation constraint
Authors: Block Kai Tobias , Uecker Martin , Frahm Jens
Published: May 2007

The reconstruction of artifact‐free images from radially encoded MRI acquisitions poses a difficult task for undersampled data sets, that is for a much lower number of spokes in k‐space than data samples per spoke. Here, we developed an iterative reconstruction method for undersampled radial MRI which (i) is based on a nonlinear optimization, (ii) allows for the incorporation of prior knowledge with use of penalty functions, and (iii) deals with data from multiple coils. The procedure arises as a two‐step mechanism which first estimates the coil profiles and then renders a final image that complies with the actual observations. Prior knowledge is introduced by penalizing edges in coil profiles and by a total variation constraint for the final image. The latter condition leads to an effective suppression of undersampling (streaking) artifacts and further adds a certain degree of denoising. Apart from simulations, experimental results for a radial spin‐echo MRI sequence are presented for phantoms and human brain in vivo at 2.9 T using 24, 48, and 96 spokes with 256 data samples. In comparison to conventional reconstructions (regridding) the proposed method yielded visually improved image quality in all cases. Magn Reson Med 57:1086–1098, 2007. © 2007 Wiley‐Liss, Inc.
XTC MRI: Sensitivity improvement through parameter optimization
Authors: Ruppert Kai , Mata Jaime F. , Wang Hsuan‐Tsung J. , Tobias William A. , Cates Gordon D. , Brookeman James R. , Hagspiel Klaus D. , Mugler John P.
Published: May 2007

Xenon polarization Transfer Contrast (XTC) MRI pulse sequences permit the gas exchange of hyperpolarized xenon‐129 in the lung to be measured quantitatively. However, the pulse sequence parameter values employed in previously published work were determined empirically without considering the now‐known gas exchange rates and the underlying lung physiology. By using a theoretical model for the consumption of magnetization during data acquisition, the noise intensity in the computed gas‐phase depolarization maps was minimized as a function of the gas‐phase depolarization rate. With such optimization the theoretical model predicted an up to threefold improvement in precision. Experiments in rabbits demonstrated that for typical imaging parameter values the optimized XTC pulse sequence yielded a median noise intensity of only about 3% in the depolarization maps. Consequently, the reliable detection of variations in the average alveolar wall thickness of as little as 300 nm can be expected. This improvement in the precision of the XTC MRI technique should lead to a substantial increase in its sensitivity for detecting pathological changes in lung function. Magn Reson Med 57:1099–1109, 2007. © 2007 Wiley‐Liss, Inc.
Degenerate mode band‐pass birdcage coil for accelerated parallel excitation
Authors: Alagappan Vijayanand , Nistler Juergen , Adalsteinsson Elfar , Setsompop Kawin , Fontius Ulrich , Zelinski Adam , Vester Markus , Wiggins Graham C. , Hebrank Franz , Renz Wolfgang , Schmitt Franz , Wald Lawrence L.
Published: May 2007

An eight‐rung, 3T degenerate birdcage coil (DBC) was constructed and evaluated for accelerated parallel excitation of the head with eight independent excitation channels. Two mode configurations were tested. In the first, each of the eight loops formed by the birdcage was individually excited, producing an excitation pattern similar to a loop coil array. In the second configuration a Butler matrix transformed this “loop coil” basis set into a basis set representing the orthogonal modes of the birdcage coil. In this case the rung currents vary sinusoidally around the coil and only four of the eight modes have significant excitation capability (the other four produce anticircularly polarized (ACP) fields). The lowest useful mode produces the familiar uniform B1 field pattern, and the higher‐order modes produce center magnitude nulls and azimuthal phase variations. The measured magnitude and phase excitation profiles of the individual modes were used to generate one‐, four‐, six‐, and eightfold‐accelerated spatially tailored RF excitations with 2D and 3D k‐space excitation trajectories. Transmit accelerations of up to six‐fold were possible with acceptable levels of spatial artifact. The orthogonal basis set provided by the Butler matrix was found to be advantageous when an orthogonal subset of these modes was used to mitigate B1 transmit inhomogeneities using parallel excitation. Magn Reson Med 57:1148–1158, 2007. © 2007 Wiley‐Liss, Inc.
Finite elements for elasticity with microstructure and gradient elasticity
Authors: Zervos A.
Published: May 2007

We present a general finite element discretization of Mindlin's elasticity with microstructure. A total of 12 isoparametric elements are developed and presented, six for plane strain conditions and six for the general case of three‐dimensional deformation. All elements interpolate both the displacement and microdeformation fields. The minimum order of integration is determined for each element, and they are all shown to pass the single‐element test and the patch test. Numerical results for the benchmark problem of one‐dimensional deformation show good convergence to the closed‐form solution. The behaviour of all elements is also examined at the limiting case of vanishing relative deformation, where elasticity with microstructure degenerates to gradient elasticity. An appropriate parameter selection that enforces this degeneration in an approximate manner is presented, and numerical results are shown to provide good approximation to the respective displacements and strains of a gradient elastic solid. Copyright © 2007 John Wiley & Sons, Ltd.
The social security earnings test and work incentives
Authors: Benítez‐Silva Hugo , Heiland Frank
Published: May 2007

The labor supply and benefit claiming incentives provided by the early retirement rules of the Social Security Old Age benefits program are of growing importance as the Normal Retirement Age (NRA) increases to 67, the labor force participation of Older Americans rises, and a variety of reforms to the Social Security system are considered. Any reform needs to take into account the effects and rationale of the Social Security Earnings Test and the Actuarial Adjustment Factor, which are likely to be widely misunderstood due to the relatively little attention paid by policymakers and researchers to the fact that Americans are willing to work while receiving benefits. We describe these incentives and emphasize that individuals who claim benefits before the NRA but continue to work, or return to the labor force, can reduce the early retirement penalty by suspending the collection of monthly benefits if they earn above the Earnings Test limit. We then argue that the Earnings Test can be distortionary and is costly to administer, and that these characteristics are inflated by the lack of information given to Older Americans regarding the consequences of working while receiving retirement benefits. We present results from statistical models of labor force exit behavior using data from the Health and Retirement Study showing the relevance of these incentives, and investigate the importance of informational asymmetries among beneficiaries regarding benefit withholding using a dynamic life‐cycle model of labor supply and benefit claiming. We then use the latter framework to compare the behavioral and welfare implications of a removal of the Earnings Test to the policy of providing more information regarding the Earnings Test and the adjustment of the rate of benefit pay to Older Americans. © 2007 by the Association for Public Policy Analysis and Management
The performance of charter schools in Wisconsin
Authors: Witte John , Weimer David , Shober Arnold , Schlomer Paul
Published: May 2007

How have charter schools in Wisconsin performed relative to traditional public schools? Two analyses provide an answer: First, a comparison of achievement test scores for students in Milwaukee charter and traditional schools from 1998 to 2002 for grades 3 through 10 finds a relative advantage for charter school students using fixed effects and first difference specifications. Second, a methodological approach new to the debate over performance in choice schools assesses schoollevel standardized tests in the fourth and eighth grades for 2000–01 and 2001–02. The results for fourth grade are generally favorable for charter schools; those for eighth grade are mixed. Overall, the results from these two analyses suggest that charter schools in Wisconsin are performing somewhat better than the traditional public schools from which they draw students. © 2007 by the Association for Public Policy Analysis and Management
Income tax policy and charitable giving
Authors: Brooks Arthur C.
Published: May 2007

Many studies over the past 20 years have looked at the response of charitable donations to tax incentives—the tax price elasticity of giving. Generally, authors have assumed this elasticity is constant across all types of giving. Using the 2001 Panel Study of Income Dynamics data on charitable giving, this paper estimates the tax price elasticity across six nonprofit subsectors, finding substantial variation. These results suggest that the fiscal effectiveness of tax deductibility depends on the type of donation involved. This has implications for both public policy and nonprofit management. © 2007 by the Association for Public Policy Analysis and Management
Disproportionate representation of KRAS gene mutation in atypical adenomatous hyperplasia, but even distribution of EGFR gene mutation from preinvasive to invasive adenocarcinomas
Authors: Sakamoto H , Shimizu J , Horio Y , Ueda R , Takahashi T , Mitsudomi T , Yatabe Y
Published: May 2007

In the resected lung, additional small lesions are occasionally found incidentally, and include the full spectrum of preinvasive to invasive lesions under the current putative schema of the sequential development of lung cancer. In this study, we examined EGFR and KRAS gene mutations in 119 synchronous pulmonary lesions, including 40 precursor lesions (atypical adenomatous hyperplasia, AAH), 26 carcinomas in situ (non‐mucinous bronchioloalveolar carcinoma, BAC), 14 minimally invasive adenocarcinomas, 34 overt invasive adenocarcinomas, and five of other subtypes of cancer. Although the mutually exclusive nature of KRAS and EGFR gene mutations was maintained even in preinvasive lesions, the incidences of the lesions along the putative progression schema were quite different. The KRAS gene was mutated in 33% of AAH, 12% of carcinomas in situ, 8% of minimally invasive adenocarcinomas and 0% of well‐differentiated adenocarcinomas, whereas the frequencies of EGFR mutation did not fluctuate greatly, at 25%, 51%, 36%, 86% and 67%, respectively. These results are consistent with the findings of a published gene‐targeted mouse model; the mice expressing oncogenic KRAS developed AAH but not invasive adenocarcinoma, whereas a spectrum of preinvasive to invasive adenocarcinomas was observed in the mice expressing mutant EGFR. Taking these factors together, it is suggested that AAH could develop by either KRAS or EGFR gene mutation, but AAH harbouring a KRAS gene mutation might not progress further to an invasive cancer. Copyright © 2007 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Characterisation of fungal lanostane‐type triterpene acids by electrospray ionisation mass spectrometry
Authors: Cabrera Gabriela M. , Vellasco Adriana P. , Levy Laura M. , Eberlin Marcos N.
Published: May 2007

Lanostane‐triterpene acids obtained from the culture of the fungus Coriolellus malicola were studied by electrospray mass spectrometry in the negative ion mode using quadrupole time‐of‐flight and quadrupole ion trap analysers. Despite the differences observed in the mass spectra recorded with these instruments, a set of fragment ions was found to be characteristic of the family, depending on the Δ7,9(11) or Δ8 skeleton and the particular functional group at C‐3. Copyright © 2007 John Wiley & Sons, Ltd.