bluuebunny/crossref_metadata_2025 huggingface dataset:
A Bioorganometallic Approach for the Electrochemical Detection of Proteins: A Study on the Interaction of Ferrocene–Peptide Conjugates with Papain in Solution and on Au Surfaces
Authors: Mahmoud Khaled A. , Kraatz Heinz‐Bernhard
Published: April 2007

In this paper, a new bioorganometallic approach for the detection of proteins using surface‐bound ferrocene–peptide conjugates is presented. Specifically, a series of peptide conjugates of 1′‐aminoferrocene‐1‐carboxylic acid (ferrocene amino acid, Fca) is synthesized: Boc‐Fca‐Gly‐Gly‐Tyr(Bzl)‐Arg(NO2)‐OMe (2), Thc‐Fca‐Gly‐Gly‐Tyr(Bzl)‐Arg(NO2)‐OMe (3), Thc‐Fca‐Gly‐Gly‐Tyr(Bzl)‐Arg(NO2)‐OH (4), Boc‐Fca‐Gly‐Gly‐Arg(Mtr)‐Tyr‐OMe (7), Thc‐Fca‐Gly‐Gly‐Arg(Mtr)‐Tyr‐OMe (8), Thc‐Fca‐Gly‐Gly‐Arg(Mtr)‐Tyr‐OH (9), Thc‐Fca‐Gly‐Gly‐Arg‐Tyr‐OH (10). The peptide is conjugated to the C‐terminal side of Fca and compounds 4, 7–10 possess a thiostic acid linked to the N‐terminal side of Fca in order to facilitate formation of thin films on gold substrates. Competitive inhibition towards papain was determined for Thc‐Fca‐Gly‐Gly‐Tyr(Bzl)‐Arg(NO2)‐OH (4), Thc‐Fca‐Gly‐Gly‐Arg(Mtr)‐Tyr‐OH (9) and Thc‐Fca‐Gly‐Gly‐Arg‐Tyr‐OH (10). The binding interaction between the peptide modified substrates and papain enzyme was studied using real‐time surface plasmon resonance (SPR) imaging. Peptide 10 showed the strongest binding affinity to papain. Adsorption/desorption rate constants were ka=1.75±0.05×105 M−1 s−1 and kd=2.90±0.05×10−2 s−1. Interactions of papain with Fca–peptide 10 were investigated by cyclic voltammetry. The interaction results were also verified by measuring the electrochemical response of the peptide–papain interaction as function of increasing enzyme concentration. A linear relationship was observed for papain concentration of up to 80 nM. Shifting to higher potentials as well as decrease in the overall signal intensity was observed. The detection limit was 4×10−9 M.
Assembly of Infinite Silver(I) Columns, Chains, and Bridged Aggregates with Supramolecular Synthon Bearing Substituted Phenylethynides
Authors: Zhao Liang , Zhao Xiao‐Li , Mak Thomas C. W.
Published: April 2007

Structural correlation in a series of eight silver(I) complexes bearing substituted phenylethynide ligands was systematically investigated through variation of the position or steric bulk of substituents on the aromatic ring. All coordination frameworks are constructed with the supramolecular synthon ArCC⊃Agn (Ar=4‐MeC6H4, 3‐MeC6H4, 2‐MeC6H4, 4‐tBuC6H4, 3,5‐(CF3)2C6H3; n=4, 5), and the presence of coexisting ligands was found to influence the supramolecular assembly. The role of π–π stacking, CH⋅⋅⋅π and Ag–C(aromatic) interactions in stabilizing the coordination networks is also discussed.
First Synthesis of 2′‐Deoxyfluoropuromycin Analogues: Experimental Insight into the Mechanism of the Staudinger Reaction
Authors: Charafeddine Adib , Dayoub Wissam , Chapuis Hubert , Strazewski Peter
Published: April 2007

The N6,N6‐dedimethyl‐2′‐deoxyfluoro analogue of puromycin (= 3′‐deoxy‐N6,N6‐dimethyl‐3′‐[O‐methyltyrosylamido]adenosine), its 2′,3′‐regioisomer and a 3′‐cytidyl‐5′‐(2′‐deoxyfluoro)puromycyl dinucleotide analogue were synthesized following an approach involving i) the diastereospecific nitrite‐assisted formation of a lyxo nucleosidic 2′,3′‐epoxide from an adenosine‐2′,3′‐ditriflate derivative in a biphasic solvent mixture; ii) the regio‐ and stereoselective epoxide ring opening with sodium azide under mildly acidic aqueous conditions, iii) the stereospecific introduction of the fluor atom using DAST and iv) the reaction between the nucleosidyl or dinucleotidyl azide and an active ester of the N‐protected amino acid using highly efficient solution conditions for the Staudinger–Vilarrasa coupling, to obtain the corresponding carboxamide directly from the in situ formed iminophosphorane. This coupling reaction furnished sterically quite demanding amides in 94 % isolated yields under very mild conditions and should therefore be of a more general value. Under certain reaction conditions we isolated (amino)acyltriazene derivatives from which dinitrogen was not eliminated. These secondary products are trapped and stabilized witnesses of the first intermediate of the Staudinger reaction, the phosphatriazenes (phosphazides, triazaphosphadienes) which usually eliminate dinitrogen in situ and rapidly rearrange into iminophosphoranes, unless they are derived from conjugated or sterically bulky azides and phosphines. The acyltriazenes could either be thermally decomposed or converted to the corresponding N‐alkyl carboxamides through proton‐assisted elimination of dinitrogen. All compounds were carefully characterized through MS spectrometry, 1H, 19F, 31P and 13C NMR spectroscopy.
Topological Study of Pseudo‐Cubic Hydrogen‐Bond Networks in a Binary System Composed of Primary Ammonium Carboxylates: An Analogue of an Ice Cube
Authors: Yuge Tetsuharu , Tohnai Norimitsu , Fukuda Takeyoshi , Hisaki Ichiro , Miyata Mikiji
Published: April 2007

Hierarchical classification and single‐crystal X‐ray analysis of unique pseudo‐cubic hydrogen‐bond networks composed of primary ammonium carboxylates were carried out. The networks consist of four carboxylate anions and four primary ammonium cations at the corners of the cube, and twelve charge‐assisted NH⋅⋅⋅O hydrogen bonds on the sides of the cube. The configuration of the carboxylate anions generates topological diversity in the network. The results of this hierarchical classification showed that pseudo‐cubic hydrogen‐bond networks composed of primary ammonium carboxylates can form nine topologically different networks. These pseudo‐cubic networks are a subset of the networks formed by octameric water in the form of an “ice cube”. The classification system can be applied to other pseudo‐cubic networks in a similar way. A survey of crystal structures based on combinations of triphenylacetic acid with various alkylamines (carbon numbers up to eight) and examination of the CSD (Cambridge Structural Database) showed eight salts that form such networks in their crystal structures. These structures are classified into six topologically different networks. Similar networks composed of other salts are also discussed from a topological point of view.
Selective Treatment of Cancer: Synthesis, Biological Evaluation and Structural Elucidation of Novel Analogues of the Antibiotic CC‐1065 and the Duocarmycins
Authors: Tietze Lutz F. , Major Felix , Schuberth Ingrid , Spiegl Dirk A. , Krewer Birgit , Maksimenka Katja , Bringmann Gerhard , Magull Jörg
Published: April 2007

Novel diastereomerically pure β‐D‐galactosidic prodrugs (+)‐12 a–e of the cytotoxic antibiotics CC‐1065 and the duocarmycins were prepared for an antibody directed enzyme prodrug therapy (ADEPT) using 4 as a substrate via a radical cyclization to give rac‐5 and rac‐6 followed by a chromatographic resolution of the enantiomers of rac‐5, glycosidation and linkage to the DNA‐binding units 10 a–e. These only slightly toxic compounds can be toxified enzymatically by an antibody–β‐D‐galactosidase conjugate at the surface of malignant cells to give the cytotoxic drugs, which then alkylate DNA. The new prodrugs were tested in in vitro cytotoxicity assays showing excellent QIC50 values of 4800 and 4300 for (+)‐12 a and (+)‐12 b, respectively. The absolute configuration of precursor (+)‐5 was determined by comparison of the experimental CD spectrum with the theoretically predicted CD spectra and by X‐ray structure analysis.
Organometallic Polymers Assembled from Cation–π Interactions: Use of Ferrocene as a Ditopic Linker Within the Homologous Series [{(Me3Si)2NM}2⋅(Cp2Fe)]∞ (M=Na, K, Rb, Cs; Cp=cyclopentadienyl)
Authors: Morris J. Jacob , Noll Bruce C. , Honeyman Gordon W. , O'Hara Charles T. , Kennedy Alan R. , Mulvey Robert E. , Henderson Kenneth W.
Published: April 2007

Addition of ferrocene to solutions of alkali metal hexamethyldisilazides M(HMDS) in arenes (in which M=Na, K, Rb, Cs) allows the subsequent crystallization of the homologous series of compounds [{(Me3Si)2NM}2⋅ (Cp2Fe)]∞ (1–4). Similar reactions using LiHMDS led to the recrystallization of the starting materials. The crystal structures of 1–4 reveal the formation of one‐dimensional chains composed of dimeric [{M(HMDS)}2] aggregates, which are bridged through neutral ferrocene molecules by η5‐cation–π interactions. In addition, compounds 3 and 4 also contain interchain agostic MC interactions, producing two‐dimensional 44‐nets. Whereas 1 and 2 were prepared from toluene, the syntheses of 3 and 4 required the use of tert‐butylbenzene as the reaction media. The attempted crystallization of 3 and 4 from toluene resulted in formation of the mixed toluene/ferrocene solvated complexes [{(Me3Si)2NM)2}2⋅ (Cp2Fe)x⋅(Tol)y]∞ (in which M=Rb, x=0.6, y=0.8, 5; M=Cs, x=0.5, y=1, 6). The extended solid‐state structures of 5 and 6 are closely related to the 44‐sheets 3 and 4, but are now assembled from a combination of cation–π, agostic, and π–π interactions. The charge‐separated complex [K{(C6H6)2Cr}1.5(Mes)][Mg(HMDS)3] (15) was also structurally characterized and found to adopt an anionic two‐dimensional 63‐network through doubly η3‐coordinated bis(benzene)chromium molecules. DFT calculations at the B3 LYP/6–31G* level of theory indicate that the binding energies of both ferrocene and toluene to the M(HMDS) dimers increases in the sequence Li<Na<K. This pattern is a consequence of the larger metals allowing more open coordination spheres to support cation–π contacts. By comparison, binding of the isolated metal cations to the aromatic groups follow the reverse order K<Na<Li. A combined analysis of theoretical and experimental data suggest that ferrocene is a stronger cation–π donor than toluene for the lighter metals, but that this difference is eliminated on descending the group.
6‐Substituted Pyrrolo[3,4‐c]pyrazoles: An Improved Class of CDK2 Inhibitors
Authors: Brasca Maria Gabriella , Albanese Clara , Amici Raffaella , Ballinari Dario , Corti Luca , Croci Valter , Fancelli Daniele , Fiorentini Francesco , Nesi Marcella , Orsini Paolo , Orzi Fabrizio , Pastori Wilma , Perrone Ettore , Pesenti Enrico , Pevarello Paolo , Riccardi‐Sirtori Federico , Roletto Fulvia , Roussel Patrick , Varasi Mario , Vulpetti Anna , Mercurio Ciro
Published: April 2007

We have recently reported a new class of CDK2/cyclin A inhibitors based on a bicyclic tetrahydropyrrolo[3,4‐c]pyrazole scaffold. The introduction of small alkyl or cycloalkyl groups in position 6 of this scaffold allowed variation at the other two diversity points. Conventional and polymer‐assisted solution phase chemistry provided a way of generating compounds with improved biochemical and cellular activity. Optimization of the physical properties and pharmacokinetic profile led to a compound which exhibited good efficacy in vivo on A2780 human ovarian carcinoma.
Meta‐analysis of racial disparities in survival in association with socioeconomic status among men and women with colon cancer
Authors: Du Xianglin L. , Meyer Tamra E. , Franzini Luisa
Published: April 2007

BACKGROUND.

Few studies have addressed racial disparities in survival for colon cancer by adequately incorporating both treatment and socioeconomic factors, and the findings from those studies have been inconsistent. The objectives of the current study were to systematically review the existing literature and provide a more stable estimate of the measures of association between socioeconomic status and racial disparities in survival for colon cancer by undertaking a meta‐analysis.

METHODS.

For this meta‐analysis, the authors searched the MEDLINE database to identify articles published in English from 1966 to August 2006 that met the following inclusion criteria: original research articles that addressed the association between race/ethnicity and survival in patients with colon or colorectal cancer after adjusting for socioeconomic status. In total, 66 full articles were reviewed, and 56 of those articles were excluded, which left 10 studies for the final analysis.

RESULTS.

The pooled hazard ratio (HR) for African Americans compared with Caucasians was 1.14 (95% confidence interval [95% CI], 1.00–1.29) for all‐cause mortality and 1.13 (95% CI, 1.01–1.28) for colon cancer‐specific mortality. The test for homogeneity of the HR was statistically significant across the studies for all‐cause mortality (Q = 31.69;P< .001) but was not significant across the studies for colon cancer‐specific mortality (Q = 7.45;P= .114).

CONCLUSIONS.

Racial disparities in survival for colon cancer between African Americans and Caucasians were only marginally significant after adjusting for socioeconomic factors and treatment. Attempts to modify treatment and socioeconomic factors with the objective of reducing racial disparities in health outcomes may have important clinical and public health implications. Cancer 2007. © 2007 American Cancer Society.
Cost‐effectiveness of colorectal cancer screening with computed tomography colonography
Authors: Pickhardt Perry J. , Hassan Cesare , Laghi Andrea , Zullo Angelo , Kim David H. , Morini Sergio
Published: April 2007

BACKGROUND

Prior cost‐effectiveness models analyzing computed tomography colonography (CTC) screening have assumed that patients with diminutive lesions (≤5 mm) will be referred to optical colonoscopy (OC) for polypectomy. However, consensus guidelines for CTC recommend reporting only polyps measuring ≥6 mm. The purpose of the current study was to assess the potential harms, benefits, and cost‐effectiveness of CTC screening without the reporting of diminutive lesions compared with other screening strategies.

METHODS

The cost‐effectiveness of screening with CTC (with and without a 6‒mm reporting threshold), OC, and flexible sigmoidoscopy (FS) were evaluated using a Markov model applied to a hypothetical cohort of 100,000 persons age 50 years.

RESULTS

The model predicted an overall cost per life‐year gained relative to no screening of $4361, $7138, $7407, and $9180, respectively, for CTC with a 6‒mm reporting threshold, CTC with no threshold, FS, and OC. The incremental costs associated with reporting diminutive lesions at the time of CTC amounted to $118,440 per additional life‐year gained, whereas the incidence of colorectal cancer was reduced by only 1.3% (from 36.5% to 37.8%). Compared with primary OC screening, CTC with a 6‒mm threshold resulted in a 77.6% reduction in invasive endoscopic procedures (39,374 compared with 175,911) and 1112 fewer reported OC‐related complications from perforation or bleeding.

CONCLUSIONS

CTC with nonreporting of diminutive lesions was found to be the most cost‐effective and safest screening option evaluated, thereby providing further support for this approach. Overall, the removal of diminutive lesions appears to carry an unjustified burden of costs and complications relative to the minimal gain in clinical efficacy. Cancer 2007. © 2007 American Cancer Society.
Quality of life after surgery, external beam irradiation, or brachytherapy for early‐stage prostate cancer
Authors: Litwin Mark S. , Gore John L. , Kwan Lorna , Brandeis Judson M. , Lee Steve P. , Withers H. Rodney , Reiter Robert E.
Published: April 2007

BACKGROUND.

The primary treatments for clinically localized prostate cancer confer equivalent cancer control for most patients but disparate side effects. In the current study, the authors sought to compare health‐related quality of life (HRQOL) outcomes after the most commonly used treatments.

METHODS.

A total of 580 men completed the Medical Outcomes Study Short Form‐36, the University of California‐Los Angeles (UCLA) Prostate Cancer Index, and the American Urological Association Symptom Index before and through 24 months after treatment with radical prostatectomy (RP), external beam radiation therapy (EBRT), or brachytherapy (BT).

RESULTS.

General HRQOL did not appear to be affected by treatment. Obstructive and irritative urinary symptoms were more common after BT (P < .001). Urinary control and sexual function were better after EBRT than BT (P < .001 and P = .02, respectively) and better after BT than RP (P < .001 and P = .01, respectively). Among potent men, recovery of sexual function was best after EBRT and was equivalent after bilateral nerve‐sparing surgery or BT. Sexual bother was more common than urinary or bowel bother after all 3 treatments. Bowel dysfunction was more common after EBRT or BT than RP (P < .001).

CONCLUSIONS.

In the current study, treatment for localized prostate cancer was found to differentially affect HRQOL outcomes. Urinary control and sexual function were better after EBRT, although bilateral nerve‐sparing surgery diminished these differences among potent men undergoing RP. BT caused more obstructive and irritative symptoms, while both forms of radiation caused more bowel dysfunction. These results may inform medical decision‐making in men with localized prostate cancer. Cancer 2007. © 2007 American Cancer Society.
Impact of Bridging Units on the Dynamics of Photoinduced Charge Generation and Charge Recombination in Donor–Acceptor Dyads
Authors: Van Vooren Antoine , Lemaur Vincent , Ye Aijun , Beljonne David , Cornil Jérôme
Published: April 2007

We estimate, at a full quantum‐chemical level, the various molecular parameters governing the rate of photoinduced charge generation and charge recombination in model organic structures containing a donor and an acceptor unit in view of the possible use of such systems in organic solar cells. The rate of through‐space excitation dissociation, as predicted in the framework of the Marcus–Levich–Jortner theory, is found to be low in comparison to intramolecular decay processes when the donor and acceptor molecules are lying in a head‐to‐tail arrangement and high when the donor and acceptor molecules are superimposed in a cofacial arrangement. The charge separation rates for side‐by‐side donor–acceptor dyads are significantly increased by promoting through‐bond interactions in covalently linked donor and acceptor units. This has motivated a detailed quantitative analysis of the influence of the nature, size, and conformation of the bridging moiety on the calculated transfer rates.
Early weaning decreases play‐fighting behavior during the postweaning developmental period of wistar rats
Authors: Shimozuru Michito , Kodama Yuka , Iwasa Takashi , Kikusui Takefumi , Takeuchi Yukari , Mori Yuji
Published: April 2007

We examined the influence of early weaning on the development of play‐fighting behaviors and anxiety status in Wistar rats. Pups were divided into two groups, those weaned at postnatal day (PD) 16 (early‐weaned group) and those weaned at PD30 (normally weaned group), and were housed in pairs of the same sex. Playful interactions were measured for each pair once a week from 4 to 7 weeks of age. Thereafter, during early adulthood, all the rats were subjected to the elevated plus‐maze test. The frequencies of pinning and playful attack were less in the early‐weaned group than in the normally weaned group. In the elevated plus‐maze test, rat pups in the early‐weaned group had higher anxiety levels. The results showed that deprivation of mother–pup interactions during the preweaning period decreases affiliative interactions between cage mates, including play‐fighting behaviors during the postweaning developmental period, and increases anxiety levels during early adulthood. © 2007 Wiley Periodicals, Inc. Dev Psychobiol 49: 343–350, 2007.
Assessment of motor control using kinematics analysis in preschool children born very preterm
Authors: Sagnol Christophe , Debillon Thierry , Debû Bettina
Published: April 2007

The aim of this study was to better understand the mechanisms underlying the motor difficulties encountered by children born very preterm (VPT) without major sequelae from preterm birth. We compared the organization of visuo‐manual aiming in preterm and full term (FT) preschool aged children based on performance and kinematics data. Twenty preterm (4 females, 16 males) and 20 sex‐ and age‐matched FT children were divided into two age groups (mean age: 3 years‐4 months, and 5 years). Comparison of the performance data showed differences between the older preterm and FT children. Kinematics data revealed differences in movement control between the younger preterm and FT children. The younger FT children did not differ from the older children. In addition, there was an effect of age on both performance and kinematics data for the preterm children only. The pattern of results suggests difficulties in integrating sensory information for movement control in the preterm groups, leading to a delay in the development of visuo‐manual coordination. Kinematics analyses may help identify children at risk for poor school performance. © 2007 Wiley Periodicals, Inc. Dev Psychobiol 49: 421–432, 2007.
Infants' visual‐proprioceptive intermodal perception with imperfect contingency information
Authors: Schmuckler Mark A. , Jewell Derryn T.
Published: April 2007

Two experiments explored 5‐month‐old infants' recognition of self‐movement in the context of imperfect contingencies between felt and seen movement. Previous work has shown that infants can discriminate a display of another child's movements from an on‐line video display of their own movements, even when featural information is removed. These earlier findings were extended by demonstrating self versus other discrimination when the visual information for movement was an unrelated object (a fluorescent mobile) directly attached to the child's leg, thus producing imperfect spatial and temporal contingency information. In contrast, intermodal recognition failed when the mobile was indirectly attached to infants' legs, thus eliminating spatial contingencies altogether and further weakening temporal contingencies. Together, these studies reveal that even imperfect contingency information can drive intermodal perception, given appropriate levels of spatial and temporal contingency information. © 2007 Wiley Periodicals, Inc. Dev Psychobiol 49: 387–398, 2007.
Early experience affects the traits of monogamy in a sexually dimorphic manner
Authors: Bales Karen L. , Lewis‐Reese Antoniah D. , Pfeifer Lisa A. , Kramer Kristin M. , Carter C. Sue
Published: April 2007

The goal of this study was to examine the effects of early life experiences on the subsequent expression of traits characteristic of social monogamy in prairie voles (Microtus ochrogaster). During cage changes parents and their offspring were either transferred between cages in a cup (zero manipulation, MAN0) or with a gloved hand (one manipulation, MAN1). Following weaning the offspring were tested for alloparental behavior. In adulthood they were tested for the capacity to form partner preferences, behavior in an elevated plus‐maze (EPM), and corticosterone levels. MAN0 males (but not females) showed lower levels of alloparental behavior than MAN1 males. MAN0 females (but not males) were less likely to form pair bonds than MAN1 females. MAN0 animals of both sexes were less exploratory in the EPM than MAN1 counterparts. These experiments support the hypothesis that behaviors used to characterize monogamy are vulnerable in a sex‐specific manner to early experience. © 2007 Wiley Periodicals, Inc. Dev Psychobiol 49: 335–342. 2007.
Gilbert Gottlieb (1929–2006)
Authors: Bateson Patrick , Logan Cheryl
Published: April 2007

Gilbert Gottlieb, a pioneer in developmental psychobiology, died on July 13, 2006. We pay tribute to the man, to his career, and to his dedication to developmental science. © 2007 Wiley Periodicals, Inc. Dev Psychobiol 49: 446–449, 2007.
Adult and peer influences on starling song development
Authors: Bertin Aline , Hausberger Martine , Henry Laurence , Richard‐Yris Marie‐Annick
Published: April 2007

Adult influence on song development was rarely investigated in complex social settings. We investigated the influence of the young/adult ratio on song learning in European starlings. Starling songs are composed of two categories: whistles and warbling. Warbling includes three parts: complex variable motifs, click motifs, and high frequency motifs. Song learning by young birds raised in group (G birds), in group with adults (GT birds) or in pair with one adult (IT birds) were compared. Song tutor choice, song sharing, and song quality varied with social context. The mere presence of adults in a group was not sufficient for young to develop all adult song features. Only IT birds chose adults as tutors. Social contact with only one adult enhanced acquisition of whistles, click motifs, individuality, and reduced the number of high frequency motifs (adult song features). This study suggests that the adult influence is proportional to young/adult ratio. © 2007 Wiley Periodicals, Inc. Dev Psychobiol 49: 362–374, 2007.
Replica distribution of data associated with location on wireless ad hoc networks
Authors: Tsuchida Gen , Okino Tomoyuki , Tamori Masahiro , Watanabe Takashi , Mizuno Tadanori , Ishihara Susumu
Published: April 2007

In mobile ad hoc networks, due to the change of topology caused by the movement of hosts and the change of radio link status, it is difficult for mobile hosts to retain accessibility to data on other hosts. To solve such a problem, replica distribution methods which distribute replicas of data items to other mobile hosts and maintain them have been proposed. In this paper, we propose and evaluate a method to enhance the accessibility to data items that are associated with locations and requested by Geocast from hosts. This method is based on flooding of replicas of data items, and it uses the locations of mobile hosts and the associated locations of data items for controlling the range of the replications and the redundancy of the replicas. Furthermore, to keep the accessibility to such data high, replicas are dynamically relocated after the movement of hosts. We confirmed the effectiveness of the proposed method by detailed simulations including multiple data request models. Simulation results showed that the proposed method achieves high accessibility to location‐dependent data especially when the storage size is small. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(10): 67– 80, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20320
A decoding method for Tornado‐type codes utilizing error packets
Authors: Yamato Ryohei , Umehara Daisuke , Morihiro Yoshiteru , Noguchi Taku , Kawai Makoto
Published: April 2007

Satellite communications is suitable for multicast communications which can achieve one‐to‐many delivery because it can broadcast to multiple receiving stations over a wide area. However, packet retransmission is inefficient for satellite communications because of its large delay and bit error rate. In order to avoid packet retransmission, FEC (forward error correction) exploiting error correcting codes have been put to practical use in satellite multicasting. Tornado‐type codes are well known as a kind of error correcting codes suitable for multicasting. Tornado‐type codes are encoded and decoded in packets. As a result, they are effective for combatting packet losses by buffer overflow or congestion control. Furthermore, their coding and decoding have low time complexity. On the other hand, the bit errors in the packet are processed as a packet loss in decoding because the Tornado‐type codes are decoded packet‐wise. In this paper, we propose an effective decoding method for bit errors in the packets for Tornado‐type codes. We show by computer simulation that the proposed method is effective in bit error environments. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(10): 57– 66, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20361
A routing protocol for mobile terminals in an ad hoc network with established network
Authors: Yoshida Masashi , Miki Tetsuya
Published: April 2007

The expansion of a communication area and the provision of services to wide districts can be expected if ad hoc networks are connected to established networks. In this environment, two types of routes exist between mobile stations that compose ad hoc networks: routes using wireless links only and routes via base station and the established networks. However, most routing protocols decide a route simply by the minimum hop counts between mobile stations without taking the differences of communication performance between the established network and ad hoc networks into account. This paper presents a new routing protocol that uses simple formulas to decide which route is effective, a route using wireless links only, or a route via the established networks. The formulas are derived from the results of simulation on the communication performance of some routes that uses IEEE802.11b as wireless links and Ethernet of 100 Mb/s as wired links. The performance of our proposed routing protocol, which is realized as an extension of ad hoc on‐demand distance vector (AODV), is evaluated by simulation. The results show that the proposed routing protocol is effective especially under a high data rate situation compared with AODV. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(10): 47– 56, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20363
Proposed high‐efficiency packet forwarding method under multihome environment
Authors: Shiota Hiroshi , Otaka Akihiro , Nakashima Takashi , Okumura Yasuyuki
Published: April 2007

In the past few years, communication among clients, such as IP video telephony and file sharing, that is peer‐to‐peer (P2P) communication, has increased. P2P communication is often considered to be communication over relatively short geographic distances as in local communication. However, in P2P communication, the communication partner is not limited to belonging to the same Internet Service Provider (ISP) as oneself and communication may be routed over long paths known as routing through an Internet exchange (IX) even when geographically close. However, the problem becomes inefficient transmission. To solve this problem, we herein propose a multinetwork access method using multiple networks, implement efficient packet forwarding, and study the reduction in IX or ISP network traffic when this method is applied to an access network. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(10): 36– 46, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20368
New weighting method to synthesize a zero sidelobe correlation filter for burst signals
Authors: Shinonaga Mitsuyoshi , Suzuki Junichiro , Yajima Shinichi , Nishimoto Shinkichi
Published: April 2007

The detection of received radar signals uses Doppler filtering as the correlation process on the received echoes for many transmitted pulses in addition to the pulse compression process which is the correlation process in the range direction. Normal radar echoes become blips widened in the azimuth direction, but the Doppler filtering process is not the optimum process from the perspective of improving the signal‐to‐noise ratio. Furthermore, compression of the spread in the azimuth direction of the signal is demanded in order to detect the azimuth. In this paper, we show that the azimuth beam width compression process can be implemented by filtering which satisfies the maximum SNR based on the zero sidelobe constraint condition applied to pulse compression. In addition, we theoretically explain the weighting matrix derived by this design method and use simulations to compare with the pulse compression process of the characteristics of a zero sidelobe correlation function. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(10): 25– 35, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20373
Transmission performance of WDM/OFDM hybrid systems over optical fibers
Authors: Tanaka Kenichiro , Norimatsu Seiji
Published: April 2007

Orthogonal frequency division multiplexing (OFDM) can achieve high utilization efficiency. In this paper, the authors combine OFDM with wavelength division multiplexing (WDM) to investigate the optical fiber transmission characteristics of a WDM/OFDM hybrid system that can easily achieve high utilization efficiency even when the number of channels is high. They used intensity modulation (IM), differential binary phase‐shift keying (DBPSK), and differential quadrature phase‐shift keying (DQPSK) as modulation methods to show transmission characteristics related to multi‐repeater and nonrepeater systems. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(10): 14– 24, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20387
Modified calibration method for MUSIC method with an array antenna
Authors: Hirota Akimichi , Miyamoto Takehiro , Nakano Masayuki , Arai Hiroyuki
Published: April 2007

In this paper, we propose a modified calibration method to improve the accuracy of direction of arrival (DOA) estimation, and conduct simulations and experiments to verify the effectiveness of the proposed method. In a system for DOA estimation, because the accuracy of the DOA estimation is degraded by the mutual coupling among the antenna elements, these elements must be calibrated. Therefore, we propose a modified calibration method to implement these improvements while considering the mutual coupling among the elements and the manufacturing errors. We verify the effectiveness of the proposed method by simulations and improve the accuracy by about twofold compared to the conventional method in experiments. In addition, the estimation accuracy is degraded by changes in the directions of the angle of elevation and the angle of dip in the conventional method, but we demonstrate the ability to suppress degradation by applying the proposed method. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(10): 1– 13, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20398
A real‐valued periodic orthogonal sequence derived from a real‐valued shift‐orthogonal finite‐length sequence and its fast periodic correlation algorithm
Authors: Matsumoto Takahiro , Tanada Yoshihiro
Published: April 2007

This paper proposes a real‐valued orthogonal periodic sequence of a periodN=2νderived from a real‐valued shift‐orthogonal finite‐length sequence of lengthM=2ν+1. This paper also explains the principle of a fast correlation algorithm that efficiently executes periodic correlation processing for this real‐valued orthogonal periodic sequence. The sidelobe of an aperiodic autocorrelation function for a real‐valued shift‐orthogonal finite‐length sequence (length ofM) is 0 except for the right and left ends of the shift. If the subsequent sequence of first values repeatedly overlap the final values of this sequence, a real‐valued orthogonal periodic sequence of a periodN=M−1 can be obtained. A real‐valued orthogonal periodic sequence of a periodN=2νgenerated from real‐valued shift‐orthogonal finite‐length sequence of lengthM=2ν+1 is obtained by convoluting partial sequences and based on that controls the number of multiplications and the number of additions to increment on the order ofNlog2Nwithout using fast Fourier transformation. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(10): 18–28, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20294
A proposal and evaluation of a coordinated checkpointing technique using incremental snapshots
Authors: Ohara Mamoru , Arai Masayuki , Fukumoto Satoshi , Iwasaki Kazuhiko
Published: April 2007

Coordinated checkpointing techniques ensure that a consistent global state is maintained by means of coordination between processes. The approach requires that application messages temporarily cease to be exchanged but the rollback procedure when recovering from a fault is consequently simplified and the recovery costs are small. With current reductions in communications costs, the importance of coordinated techniques may be seen to be growing. However, in large‐scale systems there is a possibility that performance will be seriously impaired due to the frequent halting of the exchange of messages. In this paper we propose a method whereby coordination is performed at only a subset of the checkpoint generation points that are periodically visited while at the remaining points each process independently generates an incremental snapshot. This method aims to both alleviate the performance degradation incurred from coordination and to realize relatively high‐speed recovery. In evaluating the effectiveness of this method we estimate the checkpointing overheads and recovery costs using a probabilistic model and simulations and compare it with existing coordination methods. The results show that the proposed method is more effective than existing coordination methods from the perspective of both performance and reliability in environments with a relatively low frequency of messages. In addition, we perform comparisons of two different delta schemes for representing the incremental snapshots and discuss which environments they are each respectively suited to. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(8): 39– 53, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20296
How to derive a quantum complexity lower bound
Authors: Nishino Tetsuro
Published: April 2007

The modeling of computation using logic circuits occupies an important position in the fundamentals of complexity theory including quantum complexity theory. Consequently, research into methods for computing logic functions on quantum circuits as well as for minimizing and simplifying such circuits has become extremely important. In this paper we explicitly formulate the depth minimization problem for quantum logic circuits and show that this problem is closely related to a geometric approach to deriving a lower bound on the size of a quantum logic circuit. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(10): 9–17, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20298
A method of detection of signals corrupted by nonstationary random noise via stationarization of the data
Authors: Ijima Hiroshi , Ohsumi Akira , Okui Ryo
Published: April 2007

This paper proposes a method for detecting a signal embedded in nonstationary noise. In most past studies of the signal detection problem, random noise is considered as a stationary stochastic process, since it is mathematically easy to handle. However, the noise observed in practice contains many nonstationary elements with time‐varying (evolutionary) statistical properties. In this study, observational noise is modeled as a probability density function with slowly evolving parameters. Then, based on the evolving spectral representation, the nonstationary observation data are transformed to a stationary process. A new method is proposed as follows. It is assumed that nonstationarity remains in the stationarized observation data in the interval containing the signal, due to the effect of the signal. Then the signal is detected by testing for stationarity. In the proposed method, Priestley's evolutionary spectrum is used in the spectral representation of the nonstationary stochastic process, and the method of Okabe and colleagues based on the KM2O‐Langevin equation is used for the stationarity test. The effectiveness of the proposed method is verified by a simulation experiment. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(8): 29–38, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20302
A study on an estimation system of inverse transfer function using adaptive filter estimating minimum‐phase and allpass transfer function
Authors: Kobayashi Masaki , Itoh Yoshio , Okello James
Published: April 2007

A structure is proposed for an adaptive system with an adaptive filter located before the unknown system (pre‐inverse adaptive system) for estimation of the inverse of the transfer function (inverse transfer function) of the unknown system. In general, when an adaptive transversal filter is used as an adaptive filter, the delay signal of the output of the unknown system is needed in the adaptive algorithm for the weights. Since an adaptive filter is inserted in the front stage, this signal cannot be observed, so that a replica of the unknown system is needed. In this paper, an adaptive system that does not require this replica is discussed. Estimation of the inverse transfer function of the minimum phase of the unknown system is performed by an adaptive exponential filter and an inverse copy of the weights of the exponential filter placed in front of the unknown system. The signal within the adaptive algorithm consists of the observable input signal to the adaptive exponential filter and the estimation error. Estimation of the inverse transfer function for the allpass transfer function of the unknown system is performed by the adaptive transversal filter and the reversing copy of the weight to the transversal filter located before the unknown system. The signal in the adaptive system consists of the observable input signal to the exponential filter and the estimation error. Convergence of the weight is studied from the point of view of monotonic increase of the gradient. The unique feature of the approach is that the algorithm of the two adaptive filters consists of a gradient algorithm with guaranteed convergence for the weights and of copies of the weights after updating. Finally, a performance evaluation of the adaptive system and a comparison with conventional systems are performed by numerical simulation. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(9): 10– 17, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20305
Resolution enhancement of digital images with data‐dependent biasing
Authors: Okamoto Yasuaki , Taguchi Akira , Tokuda Masamitsu
Published: April 2007

In the information and communications field, digital images have come to be widely used in mobile communications devices, and digital image processing is very important. Because of the different resolutions of the displays and output devices in each terminal, digital images undergo reduction and enlargement processing very frequently. Conventionally, reduction and enlargement processing is performed using an interpolation algorithm based on the sinc function. However, because the frequency band increases when digital images are enlarged, an enlarged image of sufficient quality cannot be attained through interpolation. In recent years, an enlargement method has been proposed which uses estimation of the frequency bands (high‐frequency components) which increase with the enlargement of a digital image. The authors have also clarified interpolation algorithms using the preservation of step edge signals, coordinate point warping for generating peak signals, and signal amplitude biasing. They have implemented an interpolation algorithm which produces high‐frequency components. In calculating the bias in this method, the smaller of the biases found to either side of the interpolation is selected. This choice is not necessarily optimal; the larger bias should be selected depending on certain conditions. For example, the selection of the larger bias makes it possible to preserve the precipitous changes in a step edge signal. This makes it possible to preserve step edge signals and generate peaks, without also using coordinate point warping, by selecting the optimal bias according to local information. The proposed interpolation algorithm using data‐dependent biasing was compared to an interpolation algorithm using coordinate point warping and signal amplitude biasing. The proposed algorithm was found to have a similar performance and clearly shown to be a method with low computational complexity. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(8): 18–28, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20306
Stochastic complexity of complete bipartite graph‐type Boltzmann machines in mean field approximation
Authors: Nishiyama Yu , Watanabe Sumio
Published: April 2007

A variational Bayes method is proposed as an approximation method for implementing Bayesian posterior distribution with moderate computational complexity. Its effectiveness for real problems has been confirmed. The variational Bayes method is a method which generalizes the mean field approximation used in calculating partition functions in statistical physics. In recent years, the mathematical properties of the precision with which it is approximated have been investigated. In this paper, the authors consider the asymptotic stochastic complexity in the case of applying the mean field approximation to complete bipartite graph‐type Boltzmann machines and theoretically derive that asymptotic form. Also, based on the results, the authors quantitatively consider the difference between Bayesian posterior distribution and the posterior distribution of the mean field approximation. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(9): 1– 9, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20307
Characterization of sonochemical reactors by chemical dosimetry
Authors: Asakura Yoshiyuki , Maebayashi Masahiro , Matsuoka Tatsuro , Koda Shinobu
Published: April 2007

Irradiation of ultrasonic waves induces cavitation in a solution, and a chemical action instigated by radicals occurs. This chemical action is reported to be most efficient in the region of several hundred kilohertz frequencies. Application of sonochemistry based on ultrasonic chemical action remains at the laboratory scale and has not yet reached the industrial practical scale. In order to realize practical applications of sonochemistry, there is a need to scale‐up the sonochemical reactors. For this purpose, we used a 490‐kHz cylindrical sonochemical reactor that is long in the irradiation direction, and used potassium iodide (KI) dosimetry, sonochemical luminescence, and calorimetry to evaluate the sonochemical reaction efficiency and reaction field of the reactor. We performed the evaluation with the ultrasonic irradiation direction in the horizontal and vertical directions. As a result, we observed sonochemical luminescence and a rise in temperature near the reflection surface, for both the horizontal and vertical irradiation. For the horizontal irradiation, the I3− concentration was evenly distributed in the irradiation direction. Moreover, we found that the sonochemical reaction efficiency was the same for both the horizontal irradiation and the vertical irradiation. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(8): 1– 8, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20315
Algorithms for the minimum partitioning problems in graphs
Authors: Nagamochi Hiroshi
Published: April 2007

In this paper, the author explains the recent evolution of algorithms for minimum partitioning problems in graphs. When the set of vertices of a graph having non‐negative weights for edges is divided intoksubsets, the set of edges for which both endpoints are contained in different subsets is called ak‐way cut ork‐cut. The problem of obtaining thek‐way cut that minimizes the sum of the weights is an important research topic that appears in many practical applications such as VLSI design. In this paper, the author introduces recent results including cases in which sets of terminals or sets of terminal pairs that are to be separated are further specified in this problem and cases in which the objects to be partitioned are extended from graphs to hypergraphs or submodular set functions. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(10): 63– 78, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20341