bluuebunny/crossref_metadata_2025 huggingface dataset:
Pyridyl‐(2)‐alkanole und Pyridyl‐(2)‐äthylene
Authors: Profft Elmar , Linke Heinz‐Werner
Published: June 2007

Ausgehend vom α‐Picolin werden über das α‐Picolylmagnesiumhalogenid mit gesättigten, ungesättigten und substituierten aliphatischen, aromatischen und hydroaromatischen Aldehyden und ebensolchen Ketonen Pyridyl‐(2)‐alkanole synthetisiert. Die Synthese ist auf Chinaldin übertragbar. Die mit Wasserstoffperoxyd aus den Basen dargestelltenN‐Oxyde können sowohl mit nascierendem als mit katalytisch angeregtem Wasserstoff reduziert werden. Bei alkalischer Behandlung der tertiären Pyridyl‐alkanole wird eine auf der Ladungsverteilung beruhende „umgekehrte Ketolisierung”︁ nachgewiesen. Die 1‐[Pyridyl‐(2)]‐2‐alkyl‐äthylene wie 1‐[Pyridyl‐(2)]‐butadiene werden durch alkalische, die 1‐[Pyridyl‐(2)]‐2.2‐dialkyl‐äthylene durch saure Dehydratisierung aus den entsprechenden Alkanolen gewonnen. Die Beständigkeit der Äthylen‐Doppelbindung wird, im Vergleich zum 2‐Vinyl‐pyridin, durch Polymerisationsversuche bewiesen. Die Hydrochloride der höheren Pyridyl‐alkanole und der ‐äthylene sind oberflächenaktiv. Die Anlagerungsfähigkeit der Pyridyläthylene wird bei der Reaktion mit Aminen, Mercaptanen, Thiophenolen und Thioglykolsäure untersucht. Durch katalytische Hydrierung der Pyridyläthylene erhält man die Pyridylalkane, aus diesen wie aus den Äthylenen werden durch totale Reduktion die Piperidyl‐alkane gewonnen.
Die Einwirkung von Thionylchlorid auf die durch Grignardierung von Phenanthrenchinon erhältlichen Pinakone
Authors: Hauptmann Siegfried
Published: June 2007

Je nach Art der Substituenten findet bei der Einwirkung von Thionylchlorid auf die durch Grignardierung von Phenanthrenchinon erhältlichen Finakone in Gegenwart katalytischer Mengen Pyridin entweder Allylumlagerung oder Pinakolinumlagerung statt. Die Allylumlagerung des 9.10‐Dihydroxy‐9.10‐dimethyl‐9.10‐dihydro‐phenanthrens ermöglicht eine einfache Synthese des 9.10‐Dimethyl‐phenanthrens und seiner Derivate.
N‐Trifluoracetyl‐aminosäuren, XVIII. Dampfdruckmessungen an N‐TFA‐Aminosäuren, ‐Peptiden und ihren Estern
Authors: Weygand Friedrich , Klipping Gustav , Palm Dieter
Published: June 2007

Mit Hilfe des Glasfadenpendels und des Glasfedermanometers wurden die Dampfdrucke einer Reihe der in der Überschrift genannten Verbindungen gemessen. Sie sind bemerkenswert hoch. Es wurden auch die Temperaturen ermittelt, bei denen im Verlaufe von einigen Stunden eine beginnende Zersetzung festzustellen ist.
Heterocyclische Verbindungen, VII. Über die Reaktionsfähigkeit von Methylgruppen im Pteridinsystem
Authors: Henseke Günter , Müller Jürgen
Published: June 2007

Die am C‐Atom der CN‐Doppelbindungen haftenden Methylgruppen im 1.7‐Dimethyl‐ und 1.6.7‐Trimethyl‐2.4‐dioxo‐1.2.3.4‐tetrahydro‐pteridin lassen sich zu Mono‐ bzw. Dibrommethylverbindungen halogenieren, von denen sich die ersteren mit Pyridin zu Pyridiniumsalzen umsetzen. Das 1‐Methyl‐2.4‐dioxo‐6.7‐bis‐pyridiniomethyl‐1.2.3.4‐tetrahydro‐pteridin‐dibromid bildet mit Diacetyl 1.6.7‐Trimethyl‐, mit Methylglyoxal 1.7‐Dimethyl‐alloxazin. Die gleichfalls aus den Pyridiniumsalzen erhältlichen „Nitrone”︁ ergeben bei der sauren Spaltung den 1‐Methyl‐pteridin‐aldehyd‐(7) bzw. den 1‐Methyl‐pteridin‐dialdehyd‐(6.7). Letzterer kondensiert mit o‐Phenylendiamin unter Bildung eines Achtringes zu einem Benzodiazocinderivat.
Synthese von Ferrocenderivaten mittels bor‐ und halogensubstituierter Ferrocene
Authors: Nesmejanow A. N. , Ssasonowa W. A. , Drosd V. N.
Published: June 2007

Ausgehend von den aus Ferrocenyllithium darstellbaren Borsäureferrocen‐Derivaten wurde eine Reihe neuer Ferrocenhalogen‐Derivate dargestellt und gezeigt, auf welche Weise die Halogensubstitution in der Ferrocenreihe durchführbar ist. Ferner wurden Ferrocenyloxy‐Derivate und deren Ester synthetisiert und untersucht.
Eine neue Darstellung von 2‐Chlor‐cycloalken‐(1)‐carbonsäuren‐(1) und deren Hydrolyse zu α.α‐Dicarbonsäuren
Authors: Ziegenbein Willi , Lang Wolfram
Published: June 2007

Die aus cyclischen Ketonen mit Dimethylformamid und Phosgen oder Phosphoroxychlorid zugänglichen 2‐Chlor‐1‐formyl‐cycloalkene‐(1) (A) werden mit Sauerstoff in guten Ausbeuten zu 2‐Chlor‐cycloalken‐(1)‐carbonsäuren‐(1) (B) oxydiert, die sich hydrolytisch in α.ω‐Dicarbonsäuren spalten lassen.
Notiz über Derivate des 6.8a‐Diaza‐benzo[h]azulens
Authors: Veibel Stig , Hromadko Sonja Fila
Published: June 2007

Die aus o‐Phenylendiamin und Acetylaceton bzw. Benzoylaceton entstehenden Diazepine wurden mit Oxalsäure‐diäthylester nach Claisen zu tiefroten Substanzen kondensiert, die als Derivate des 6.8a‐Diaza‐benzo[h]azulens erkannt wurden.
An efficient algorithm for mobile objects localization
Authors: Salamah M. , Doukhnitch E.
Published: June 2007

A new efficient algorithm based on time of arrival to determine the position of a mobile object (MO) in a wireless environment is proposed. Since all operations in our algorithm are simple add and shift operations, it can be easily implemented in the MO's firmware or hardware to reduce the number of instructions and computational cost involved in the localization task. Simulation results show that the proposed algorithm outperforms other algorithms in terms of computational cost and implementation simplicity. Copyright © 2007 John Wiley & Sons, Ltd.
Design and performance evaluation of a mechanism to share contents over broadcast channels
Authors: Di Sorte Dario , Femminella Mauro , Reali Gianluca
Published: June 2007

In this paper, we present a novel mechanism (Wireless Data Sharing, WDS) to share popular contents between a set of second‐level (children) proxies connected to a parent proxy by means of a bandwidth‐limited, wireless, broadcast channel. The idea is as follows: when one of the children proxies requests a content from the parent proxy, the parent publishes the transmission of this content over a specific TCP connection between itself and the requesting child, so as to enable all the other children to capture it. Finally, the parent starts transmitting the content and the children may listen to the broadcast channel and sniff the content from the TCP connection. This allows users served by these proxies to decrease the time to access contents, without any additional bandwidth consumption. Furthermore, such a mechanism is able to decrease the load of the parent proxy.

This work provides a detailed description of the architecture and functions of the WDS system, with explicit reference to the prototype we implemented. This prototype enabled us to evaluate the performance of the data sharing mechanism from both user and network viewpoints. In this regard, we carried out a measurement campaign in an IEEE 802.11 environment to evaluate the performance of the mechanism quantitatively. The results show that the WDS system guarantees not only bandwidth saving, but also lower content access latency with respect to the legacy proxy hierarchy system. In addition, the signalling overhead associated with the publishing mechanism proves to be very low. Copyright © 2007 John Wiley & Sons, Ltd.
Synthesis, Upconversion Luminescence and Magnetic Properties of New Lanthanide–Organic Frameworks with (43)2(46,66,83) Topology
Authors: Weng Danfeng , Zheng Xiangjun , Chen Xiaobo , Li Licun , Jin Linpei
Published: June 2007

The synthesis and crystal structures of three new lanthanide–organic frameworks [Ln(pza)(OH)(H2O)]n (Ln = Y(1), Er(2), Yb(3); H2pza = 2,3‐pyrazinedicarboxylic acid) with helical chains and novel 2D (43)2(46,66,83) topology are reported. The topology is obtained by simplifying the dinuclear metal core as a six‐connected node and the ligand as a three‐connected linker. The upconversion property measurement gives green and red emissions coming from two‐photon excitation of Y: Er, Yb codoped coordination polymer and arising from ErIII transitions of 4S3/2/2H11/2→4I15/2 and 4F9/2→4I15/2. The magnetic properties of complexes 2 and 3 are also studied.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Protection of fatty acids against ruminal biohydrogenation in cattle
Authors: Jenkins Thomas C. , Bridges William C.
Published: June 2007

The increased need for intestinal absorption of unsaturated fatty acids in cattle is driven mainly by nutritional guidelines that promote reduced intake of saturated fatty acids by humans, and by reports of enhanced animal performance (such as reproductive performance) when additional essential fatty acids are supplied. A duodenal flow dataset was compiled from 25 published studies that provided up to 93 observations on fatty acid intakes and ruminal outflows across a multitude of unprotected and protected fat sources. Control diets with no added fat and diets containing unprotected fat sources had similar and predictable ruminal losses of unsaturated fatty acids (86% for linolenic and oleic acids, and 82% for linoleic acids). Rumen protection technologies that have emerged over the years involve either encapsulation of unsaturated fatty acids inside a microbial‐resistant shell (such as formaldehyde‐treated or lipid encapsulated), or alteration of fatty acid structure (such as calcium salts or fatty amides) to resist action of microbial enzymes. Calcium salts of fatty acids, because they are available commercially, comprised the majority of observations in the duodenal flow dataset. Meta‐analysis of the duodenal dataset that included random study effects revealed only a few instances where protected fat sources gave ruminal losses of polyunsaturated fatty acids that were appreciably lower than what was seen for unprotected fats. Future challenges include enhancing protection characteristics of existing rumen‐protected fat sources, and development and commercialization of novel protection strategies.
Microfluidics in amino acid analysis
Authors: Pumera Martin
Published: June 2007

Microfluidic devices have been widely used to derivatize, separate, and detect amino acids employing many different strategies. Virtually zero‐dead volume interconnections and fast mass transfer in small volume microchannels enable dramatic increases in on‐chip derivatization reaction speed, while only minute amounts of sample and reagent are needed. Due to short channel path, fast subsecond separations can be carried out. With sophisticated miniaturized detectors, the whole analytical process can be integrated on one platform. This article reviews developments of lab‐on‐chip technology in amino acid analysis, it shows important design features such as sample preconcentration, precolumn and postcolumn amino acid derivatization, and unlabeled and labeled amino acid detection with focus on advanced designs. The review also describes important biomedical and space exploration applications of amino acid analysis on microfluidic devices.
Contrasting roles of neural firing rate and local field potentials in human memory
Authors: Ekstrom Arne , Viskontas Indre , Kahana Michael , Jacobs Josh , Upchurch Kristen , Bookheimer Susan , Fried Itzhak
Published: June 2007

Recording the activity of neurons is a mainstay of animal memory research, while human recordings are generally limited to the activity of large ensembles of cells. The relationship between ensemble activity and neural firing rate during declarative memory processes, however, remains unclear. We recorded neurons and local field potentials (LFPs) simultaneously from the same sites in the human hippocampus and entorhinal cortex (ERC) in patients with implanted intracranial electrodes during a virtual taxi‐driver task that also included a memory retrieval component. Neurons increased their firing rate in response to specific passengers or landmarks both during navigation and retrieval. Although we did not find item specificity in the broadband LFP, both θ‐ and γ‐band LFPs increased power to specific items on a small but significant percent of channels. These responses, however, did not correlate with item‐specific neural responses. To contrast item‐specific responses with process‐specific responses during memory, we compared neural and LFP responses during encoding (navigation) and retrieval (associative and item‐specific recognition). A subset of neurons also altered firing rates nonspecifically while subjects viewed items during encoding. Interestingly, LFPs in the hippocampus and ERC increased in power nonspecifically while subjects viewed items during retrieval, more often during associative than item‐recognition. Furthermore, we found no correlation between neural firing rate and broadband, θ‐band, and γ‐band LFPs during process‐specific responses. Our findings suggest that neuronal firing and ensemble activity can be dissociated during encoding, item‐maintenance, and retrieval in the human hippocampal area, likely relating to functional properties unique to this region. © 2007 Wiley‐Liss, Inc.
Decision making in the solar age: Ecological criteria for the post‐economic era
Authors: Henderson Hazel
Published: June 2007

Note to industrial societies: traditional value systems worked in an Age of Petroleum but that age is ending. What changes do we need to make for the new Solar Age?
The creation of company cultures: The role of stories and human resource systems
Authors: Wilkins Alan L.
Published: June 2007

This article shows how informally told stories and human resource systems help create strong company cultures which can support a corporate strategy. It explains why stories are so powerful in creating company culture. It also suggests how managers can deal with negative stories and encourage the telling of positive stories both through their personal behavior and through the human resource systems they manage.
Professional/management relations: Imagery vs. action
Authors: Hall Richard H.
Published: June 2007

Managers and professionals have images about what professionalism involves. These images are used in personnel decisions and in other evaluation situations. The images used by professionals have multiple dimensions, many of which do not correspond to conventional stereotypes. The variable of power is of critical importance in developing and maintaining professional images. If management seeks to enhance the image of its personnel who are labeled professionals, it runs some risk of losing control of these personnel. The imagery of professionalization is viewed as developing more fully after individuals leave their professional training.
Developing Strategic Compensation Plans
Authors: Hufnagel Ellen M.
Published: June 2007

Successful introduction of strategically‐oriented compensation plans depends on their “fit” with the firm's overall approach to strategic planning. Proposed approaches to designing management compensation systems are examined in terms of their potential fit with three different mental models of strategy and the strategic planning process to develop a parallel typology of compensation plans.
The implementation and adoption of new technology in organizations: The impact on work, people, and culture
Authors: Mirvis Philip H. , Sales Amy L. , Hackett Edward J.
Published: June 2007

This article examines the impact of computer technology on the workforce and workplace. It summarizes research and examines in practice the implementation and adoption of new technology in companies. Two cases are presented: a metal fabrication factory and a professional publishing company. Results of a pre‐implementation survey given to personnel in the factory highlight how a top‐down change strategy and worker's sense of mistrust and inequity, led to problems with the introduction of computerized machinery and control systems. Surveys taken one and three years after the introduction of word processing and data‐based management tools in the publishing company, by comparison, show how a more participatory change strategy coupled with extensive user training and support, contribute to success with technological change and alter perceptions of the company culture.
Expression of an endogenous retroviral sequence from the HERV‐H group in gastrointestinal cancers
Authors: Wentzensen Nicolas , Coy Johannes F. , Knaebel Hanns‐Peter , Linnebacher Michael , Wilz Birgit , Gebert Johannes , von Knebel Doeberitz Magnus
Published: June 2007

Human endogenous retroviruses (HERVs) account for approximately 8% of the human genome. Since the majority of HERV elements have accumulated inactivating mutations in the viral genes, only few expressed viral open reading frames (ORFs) have been described. In this study, we have analyzed the expression of a HERV‐H copy located on Xp22.3 encompassing a potential ORF immediately downstream of the viral promoter. Conventional and real time RT‐PCR based expression analysis of this specific HERV‐H sequence showed overexpression in 16 of 34 (47%) colorectal, 25 of 63 (40%) gastric and 2 of 12 (17%) pancreatic cancers, whereas no overexpression was detected in bronchial and cervical cancers. Normal human testis, placenta and breast tissue did not show expression of this sequence. CpG methylation analysis of the viral promoter revealed a loss of methylation in cell lines expressing the HERV‐H sequence as compared to nonexpressing cell lines and lymphocyte DNA derived from healthy individuals. Further investigations of the HERV‐H long terminal repeat and the HERV‐H RNA are necessary to assess the functional relevance of the HERV‐H expression. © 2007 Wiley‐Liss, Inc.
P53 codon 72 polymorphism and gastric cancer: A meta‐analysis of the literature
Authors: Zhou Yong , Li Ni , Zhuang Wen , Liu Guan‐Jian , Wu Tai‐Xiang , Yao Xun , Du Liang , Wei Mao‐Ling , Wu Xiao‐Ting
Published: June 2007

Studies investigating the association between p53 codon 72 polymorphism and gastric cancer risk report conflicting results. The objective of this study was to quantitatively summarize the evidence for such a relationship. Two investigators independently searched the Medline and Embase databases. This meta‐analysis included 12 case‐control studies, which included 1,665 gastric cancer cases and 2,358 controls. The combined results based on all studies showed that there was no significant difference in genotype distribution [Arg/Arg odds ratio (OR) = 0.96, 95% confidence interval (CI) = 0.79, 1.16; Pro/Pro (OR = 1.21, 95% CI = 0.92, 1.58); Pro/Arg (OR = 0.95, 95% CI = 0.79, 1.14)] between gastric cancer and noncancer patients. When stratifying for race, results were similar except that patients with gastric cancer had a significantly lower frequency of Arg/Arg (OR = 0.84, 95% CI = 0.72, 0.99) than noncancer patients among Asians. Stratified the various studies by the location, stage, Lauren's classification, and histological differentiation of gastric cancer, we found that (i) patients with cardia gastric cancer had a significantly higher frequency of Pro/Pro (OR = 3.20, 95% CI = 1.46,7.01) than those with noncardia gastric cancer among Asians; (ii) patients with advanced (stage III/IV) gastric cancer had a significantly higher frequency of Arg/Arg (OR = 1.48, 95% CI = 1.01, 2.16) than those with early (stage I/II) gastric cancer among Asians; (iii) patients with poor differentiation had a significantly lower frequency of Pro/Pro (OR = 0.13, 95% CI = 0.03, 0.64) than those with well differentiation among Caucasians. This meta‐analysis suggests that the p53 codon 72 polymorphism may be associated with gastric cancer among Asians, and that difference in genotype distribution may be associated with the location, stage, and histological differentiation of gastric cancer. © 2007 Wiley‐Liss, Inc.
Reduced numbers of IL‐7 receptor (CD127) expressing immune cells and IL‐7‐signaling defects in peripheral blood from patients with breast cancer
Authors: Vudattu Nalini Kumar , Magalhaes Isabelle , Schmidt Marcus , Seyfert‐Margolis Vicki , Maeurer Markus J.
Published: June 2007

Interleukin‐7‐receptor‐signaling plays a pivotal role in T‐cell development and maintenance of T‐cell memory. We studied IL‐7Rα (CD127) expression in PBMCs obtained from patients with breast cancer and examined IL‐7 receptor‐mediated downstream effects defined by STAT5 phosphorylation (p‐STAT5). Reduced numbers of IL‐7Rα‐positive cells were identified in CD4+ T‐cells as well as in a CD8+ T‐cell subset defined by CD8α/α homodimer expression in patients with breast cancer. PBMCs obtained from healthy donors (n = 19) and from patients with breast cancer (n = 19) exhibited constitutive p‐STAT5 expression in the range of 0–6.4% in CD4+ T‐cells and 0–4% in CD8+ T‐cells. Stimulation with recombinant human IL‐7 for 15 min increased p‐STAT5 expression up to 36–97% in CD4+T‐cells and to 26–90% in CD8+T‐cells obtained from healthy control donors (n = 19). In contrast, PBMCs obtained from 13/19 patients with breast cancer did not respond to IL‐7 as defined by STAT5 phosphorylation, despite expression of IL‐7Rα on T‐lymphocytes. T‐cells were further characterized for IL‐ 2 and IFN‐γ production induced by PMA/Ionomycin. PBMCs from 9/19 patients with breast cancer showed decreased IL‐2 and IFN‐γ production combined with IL‐7‐signaling defects; PBMCs from 4 patients with breast cancer exhibited deficient IL‐7‐signaling, yet intact cytokine production. Reduced numbers of IL‐7Rα‐positive cells and nonresponsiveness to IL‐7, defined by lack of STAT5 phosphorylation, characterizes the immunological profile in T‐cells from patients with breast cancer. © 2007 Wiley‐Liss, Inc.
Improvement of hyperlipidemia by indomethacin in Min mice
Authors: Niho Naoko , Mutoh Michihiro , Komiya Masami , Ohta Tsutomu , Sugimura Takashi , Wakabayashi Keiji
Published: June 2007

Apc gene‐deficient Min and Apc1309 mice feature a hyperlipidemic state with a markedly low expression level of lipoprotein lipase (LPL) compared to their wild‐type counterparts. We previously showed that induction of LPL mRNA by peroxisome proliferator‐activated receptor (PPAR) α and γ agonists or an LPL selective inducer suppresses both high serum lipid levels and intestinal polyp formation in these model animals. Since the general cyclooxygenase inhibitor, indomethacin, is known to suppress intestinal tumor development, but not to affect serum lipids, its influence in Min mice was here investigated. Treatment with 2.5, 5 and 10 ppm indomethacin in the diet for 14 weeks from 6 weeks of age caused significant dose‐dependent reduction in serum triglycerides, along with a reduction in the numbers of intestinal polyps to 25% of the untreated control value. LPL mRNA levels in the liver were slightly increased by indomethacin treatment. We further performed oligonucleotide microarray analysis and quantitative PCR analysis and found 8 lipid metabolism‐related genes, regulated by sterol regulatory element binding protein‐1c, to be modulated by indomethacin‐treatment in the Min mouse liver. Furthermore, TNFα was downregulated. These results indicate that indomethacin might suppress intestinal tumor formation together with a hyperlipidemic state by regulating LPL and other lipid metabolic factors. © 2007 Wiley‐Liss, Inc.
Persistent and remodeling hepatic preneoplastic lesions present differences in cell proliferation and apoptosis, as well as in p53, Bcl‐2 and NF‐κB pathways
Authors: Mazzantini Rogério Pietro , de Conti Aline , Moreno Fernando Salvador
Published: June 2007

During rat hepatocarcinogenesis preneoplastic lesions (PNL) emerge which may persist (pPNL) and be sites of progress to cancer or suffer remodeling (rPNL) tending to disappear. Cellular and molecular mechanisms involved in both phenotypes are not sufficiently elucidated. pPNL and rPNL cellular proliferation and apoptosis were evaluated in rats submitted to the resistant hepatocyte (RH) model, and an adjusted growth index (AGI) was established. p53, Bcl‐2, and NF‐κB p65 subunit expression was evaluated by immunohistochemistry in pPNL and rPNL. p65 expression and NF‐κB activation was evaluated by Western blot assays in whole livers. A lower number of BrdU‐stained hepatocyte nuclei/mm2 and higher number of apoptotic bodies (AB) per mm2 were observed in remodeling compared to pPNL. Cytoplasmic p53 accumulation is related to increased hepatocarcinoma malignancy. We observed that 71.3% pPNL and 25.4% rPNL (P < 0.05) presented p53 staining in the cytoplasm. Similarly, 67.7% pPNL and 23.1 % rPNL (P < 0.05) presented increased Bcl‐2 staining. Thirty‐two percent pPNL and 15.6% rPNL (P < 0.05) presented p65 staining. Compared to normal rats, increase (P < 0.05) of hepatic p65 expression and NF‐κB activation in rats submitted to the RH model was observed. In agreement to previous studies hepatic pPNL and rPNL differ regarding cell proliferation and apoptosis. Moreover, persistence and remodeling involve differences in p53, Bcl‐2, and NF‐κB pathways. These data point to molecular pathways that may direct preneoplastic lesions to spontaneously regress or to progress to cancer. J. Cell. Biochem. 103: 538–546, 2008. © 2007 Wiley‐Liss, Inc.
Improving the efficiency of the NEB reaction path finding algorithm
Authors: Galván Ignacio Fdez. , Field Martin J.
Published: June 2007

The nudged elastic band (NEB) method is a successful optimization method for obtaining minimum energy reaction paths if only the initial and final structures are known. However, the original implementation of the method had some limitations, which has meant that there has been considerable interest in proposing alternative NEB formulations, which show improved convergence behavior. In this work, we present two modifications to the standard NEB procedure. The first involves the use of a second‐order quasi‐Newton optimization technique applied separately to each of the images that form the path. The second consists of the use of an interpolating spline to represent the path. This ensures that the images along the path are evenly spaced and means that the arbitrary spring forces employed in the standard NEB method are no longer necessary. We tested these modifications on a set of small, but relatively complex, chemical systems and found that the computation time was reduced by as much as 90% compared with the standard method. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008
Block designs with large holes and α ‐resolvable BIBDs
Authors: Furino Steven C. , Mullin Ronald C.
Published: June 2007

In a (v, k, λ: w) incomplete block design (IBD) (or PBD [v, {k, w*}. λ]), the relation v ≥ (k − 1)w + 1 must hold. In the case of equality, the IBD is referred to as a block design with a large hole, and the existence of such a configuration is equivalent to the existence of a λ‐resolvable BIBD(v − w, k − 1, λ). The existence of such configurations is investigated for the case of k = 5. Necessary and sufficient conditions are given for all v and λ ≢ 2 (mod 4), and for λ ≡ 2 mod 4 with 11 possible exceptions for v. © 1993 John Wiley & Sons, Inc.
Symmetric (41,16,6)‐designs with a nontrivial automorphism of odd order
Authors: Spence Edward
Published: June 2007

If a symmetric (41,16,6)‐design has an automorphism σ of odd prime order q then q = 3 or 5. In the case q = 5 we determine all such designs and find a total of 419 nonisomorphic ones, of which 15 are self‐dual. When q = 3 a combinatorial explosion occurs and the complete classification becomes impracticable. However, we give a characterization in the particular case when σ has order 3 and fixes 11 points, and find that there are 3,076 nonisomorphic designs with this property, all of them being non self‐dual. The other remaining possibility is that σ, of order 3, fixes 5 points. In this case there are 960 orbit matrices (up to isomorphism and duality) and all but one of them yield designs. Here an incomplete investigation shows that in total there are at least 112,000 nonisomorphic designs. © 1993 John Wiley & Sons, Inc.
An infinite family of (simple) 6‐designs
Authors: Kreher Donald L.
Published: June 2007

A simple 6‐(22,8,60) designs is exhibited. It is then shown using Qui‐rong Wu's generalization of a result of Luc Teirlinck that this design together with our 6‐(14,7,4) design implies the existence of simple 6‐(23 + 16m,8,4(m + 1)(16m + 17)) designs for all positive integers m. All the above mentioned designs are halvings of the complete design. © 1993 John Wiley & Sons, Inc.
Uniform room frames with five holes
Authors: Dinitz J. H. , Lamken E. R.
Published: June 2007

In 1981, Dinitz and Stinson [2] proved that the necessary conditions were sufficient for the existence of a Room frame of type tu for all u ≥ 6. Very recently, Zhu Lie and Ge Gennian [5] constructed all t5 Room frames except for four missing orders. In this article we construct t5 Room frames for t = 11,13,17, and 19; this completes the proof that the necessary conditions are sufficient for the existence of a Room frame of type t5. © 1993 John Wiley & Sons, Inc.
On regular {v, n}‐arcs in finite projective spaces
Authors: Ueberberg Johannes
Published: June 2007

A regular {v, n}‐arc of a projective space P of order q is a set S of v points such that each line of P has exactly 0,1 or n points in common with S and such that there exists a line of P intersecting S in exactly n points. Our main results are as follows: (1) If P is a projective plane of order q and if S is a regular {v, n}‐arc with n ≥ √q + 1, then S is a set of n collinear points, a Baer subplane, a unital, or a maximal arc. (2) If P is a projective space of order q and if S is a regular {v, n}‐arc with n ≥ √q + 1 spanning a subspace U of dimension at least 3, then S is a Baer subspace of U, an affine space of order q in U, or S equals the point set Of U. © 1993 John Wiley & Sons, Inc.
On the existence of pure (v, 4, λ)‐PMD with λ = 1 and 2
Authors: Qinglin Lu
Published: June 2007

In this article, we investigate the existence of pure (v, 4, λ)‐PMD with λ = 1 and 2, and obtain the following results: (1) a pure (v, 4, 1)‐PMD exists for every positive integer v = 0 or 1 (mod 4) with the exception of v = 4 and 8 and the possible exception of v = 12; (2) a pure (v, 4, 2)‐PMD exists for every integer v ≥ 6. © 1994 John Wiley & Sons, Inc.
Embeddings of Sλ(2, 4, v)
Authors: Kong G. , Zhu L.
Published: June 2007

It is shown that the necessary condition for a given Sλ(2,4,u) to be embedded in some Sλ(2,4,v) as a subdesign, namely v ≥ 3u + 1, is also sufficient for the case of λ = 6. Combining this with the previously known results gives the same sufficiency for any positive integer λ. © 1994 John Wiley & Sons, Inc.
Minimal harmoniously colorable designs
Authors: Casse L. R. A. , O'Keefe Christine M. , Wilson B. J.
Published: June 2007

A graph G is minimal harmoniously colorable if it has a proper vertex coloring in which each pair of colors occurs exactly once on an edge. In particular, if D is a 2‐design we consider the graph G whose vertices are the points and blocks of D and where two vertices of G are adjacent if and only if the corresponding elements of D are incident. It will be shown that if D is symmetric then G is minimal harmoniously colorable if and only if D is a Hadamard design with corresponding Hadamard matrix of a certain form. We obtain some results if D is nonsymmetric, and construct two classes of nonsymmetric minimal harmoniously colorable designs. © 1994 John Wiley & Sons, Inc.
A combinatorial characterization of certain universal classes of hash functions
Authors: van Trung Tran
Published: June 2007

A new lower bound on the size of ϵ‐almost strongly universal2 classes of hash functions has recently been obtained by Stinson [8]. In this article we present a characterization of ϵ − ASU2 classes of hash functions meeting the Stinson bound in terms of combinatorial designs. © 1994 John Wiley & Sons, Inc.
Symmetric latin square and complete graph analogues of the evans conjecture
Authors: Andersen Lars Døvling , Hilton A. J. W.
Published: June 2007

With the proof of the Evans conjecture, it was established that any partial latin square of side n with a most n − 1 nonempty cells can be completed to a latin square of side n. In this article we prove an analogous result for symmetric latin squares: a partial symmetric latin square of side n with an admissible diagonal and at most n − 1 nonempty cells can be completed to a symmetric latin square of side n. We also characterize those partial symmetric latin squares of side n with exactly n or n + 1 nonempty cells which cannot be completed. From these results we deduce theorems about completing edge‐colorings of complete graphs K2m and K2m − 1 with 2m − 1 colors, with m + 1 or fewer edges getting prescribed colors. © 1994 John Wiley & Sons, Inc.
On the doyen‐wilson theorem for m‐cycle systems
Authors: Bryant Darryn E. , Rodger C. A.
Published: June 2007

In this article we consider the embedding of m‐cycle systems of order u in m‐cycle systems of order v when m is odd. When u and v are 1 or m (mod 2m) we completely settle this problem, except possibly for the smallest such embedding in some cases when u ≡ v ≡ m (mod 2m). In particular, there are no exceptions if m ∈ {7,9}, so the generalization of the Doyen‐Wilson Theorem is now settled for all odd m with m ≤ 9. © 1994 John Wiley & Sons, Inc.
On equationally defining m‐perfect 2m + 1 cycle systems
Authors: Lindner C. C. , Rodger C. A.
Published: June 2007

In this article we give a complete solution to the problem of equationally defining m‐perfect (2m + 1)‐cycle systems and of equationally defining m‐perfect directed (2m + 1)‐cycle systems. © 1994 John Wiley & Sons, Inc.
Existence of certain skew room frames with application to weakly 3‐chromatic linear spaces
Authors: Rodger C. A. , Wantland E. B. , Chen K. , Zhu L.
Published: June 2007

It is shown that for any even integer n ≥ 16 and for some b ≥ 1, there exists a skew Room frame of type 2a 4b with n = 2a + 4b. As an application, we show that for any integer v ≡ 1,4 (mod 12), there exists a weakly 3‐chromatic linear space with all lines having size 4 iff v > 16. This answers an open problem posed by Colbourn and Rosa. © 1994 John Wiley & Sons, Inc.
The structure of symmetry groups of GK(2n, G)
Authors: Duncan D. , Ihrig E.
Published: June 2007

The automorphism groups of the one‐factorizations GK(2n,G) are computed. It is shown that every 1‐factorization of K2n with a subgroup of the automorphism group that acts sharply 2‐transitively on the one‐factors must be GK(pm + 1, (Zp)m) for some odd prime p. © 1994 John Wiley & Sons, Inc.
Large sets of coverings
Authors: Etzion Tuvi
Published: June 2007

Large sets of packings were investigated extensively. Much less is known about the dual problem, i.e., large sets of coverings. We examine two types of important questions in this context; what is the maximum number of disjoint optimal coverings? and what is the minimum number of optimal coverings for which the union covers the space? We give various constructions which give the optimal solutions and some good upper and lower bounds on both questions, respectively. © 1994 John Wiley & Sons, Inc.
Theory of perpendicular arrays
Authors: Bierbrauer Jürgen , Edel Yves
Published: June 2007

The cryptographical theory of unconditional secrecy and authentication is based on design‐like structures called perpendicular arrays in the combinatorial literature. In order to meet the cryptographical requirements some additional and rather natural homogeneity conditions have to be satisfied. We develop a theory of these structures. Topics include bounds on the size, recursive and direct constructions using designs and permutation groups, as well as a link to Room cubes. © 1994 John Wiley & Sons, Inc.
Balanced arrays of strength two and nested (r, λ)‐designs
Authors: Kuriki Shinji , Fuji‐Hara Ryoh
Published: June 2007

An (r,λ)‐design with mutually balanced nested subdesigns (for brevity, (r,λ)‐design with MBN) is introduced firstly in this article. It is shown that an r,λ‐design with MBN is equivalent to a balanced array of strength 2 with s symbols. By the use of a nested design and an orthogonal array, a construction of an r,λ‐design with MBN is given. A direct construction of such an (r,λ)‐design, based on the result obtained by Wilson [15], is also given. By these constructions, new balanced arrays with s ≥ 3 are presented. © 1994 John Wiley & Sons, Inc.
A small basis for four‐line configurations in steiner triple systems. Dedicated to the memory of gemma holly griggs
Authors: Grannell M. J. , Griggs T. S. , Mendelsohn E.
Published: June 2007

Formulae for the numbers of two, three, and four‐line configurations in a Steiner triple system of order v, STS(v), are given. While the formulae for two and three‐line configurations depend only on v, the same is true for only 5 of the 16 four‐line configurations. For the other 11 and fixed v, the number of occurrences of any one of them, in particular the Pasch configuration, determines the number of occurrences of all the others. © 1995 John Wiley & Sons, Inc.
Existence results for near resolvable designs
Authors: Furino Steven
Published: June 2007

A near resolvable design, NRB(v, k), is a balanced incomplete block design whose block set can be partitioned into v classes such that each class contains every point of the design but one, and each point is missing from exactly one class. The necessary conditions for the existence of near resolvable designs are v ≡ 1 mod k and λ = k − 1. These necessary conditions have been shown to be sufficient for k ϵ {2,3,4} and almost always sufficient for k ϵ {5,6}. We are able to show that there exists an integer n0(k) so that NRB(v,k) exist for all v > n0(k) and v ≡ 1 mod k. Using some new direct constructions we show that there are many k for which it is easy to compute an explicit bound on n0(k). These direct constructions also allow us to build previously unknown NRB(v,5) and NRB(v,6). © 1995 John Wiley & Sons, Inc.
Existence of frame sols of type 2nu1
Authors: Yunqing Xu , Lie Zhu
Published: June 2007

An SOLS (self‐orthogonal latin square) of order n with n1 missing sub‐SOLS (holes) of order hi (1 ⩽ i ⩽ k), which are disjoint and spanning (i.e., Σ 1⩽i⩽knihi = n), is called a frame SOLS and denoted by FSOLS(h1n1 h2n2 …hknk). In this article, it is shown that for u ⩾ 2, an FSOLS(2nu1) exists if and only if n ⩾ 1 + u. © 1995 John Wiley & Sons, Inc.
On the classification of linear spaces of order 11
Authors: Pietsch Ch.
Published: June 2007

A linear space of order n is a pair (V,B), where V is a finite set of n elements and B is a set of subsets of V such that each 2‐subset of V is contained in exactly one element of B. The exact number of nonisomorphic linear spaces was known up to order 10. Betten and Braun [1] found that there exist at least 232,923 nonisomorphic linear spaces of order 11. We used a generalization of Ivanov's algorithm for the enumeration of block designs in order to construct all 232,929 linear spaces of order 11. The method used will be described and some data concerning line types, line lengths, and orders of automorphism groups is listed. © 1995 John Wiley & Sons, Inc.
The bigraphical t‐wise balanced designs of index two
Authors: Weiss Lisa M. , Kreher Donald L.
Published: June 2007

In this article we study the group Sm × Sn acting on the mn ordered pairs and classify all t‐wise balanced designs of index 2 that have such an automorphism group. © 1995 John Wiley & Sons, Inc.
Multiplier theorems
Authors: Arasu K. T. , Xiang Qing
Published: June 2007

We state and prove a multiplier theorem for a central element A of ZG, the group ring over Z of a group G. This generalizes most previously known multiplier theorems for difference sets and divisible difference sets. We also provide applications to show that our theorem provides new multipliers and establish the nonexistence of a family of divisible difference sets which correspond to elliptic semiplanes admitting a regular collineation group. © 1995 John Wiley & Sons, Inc.
New constructions for covering designs
Authors: Gordon Daniel M. , Patashnik Oren , Kuperberg Greg
Published: June 2007

A(v, k, t) covering design, or covering, is a family of k‐subnets, called blocks, chosen from a v‐set, such that each t‐subnet is contained in at least one of the blocks. The number of blocks is the covering's size, and the minimum size of such a covering is denoted by C(v,k,t). This paper gives three new methods for constructing good coverings; a greedy algorithm similar to Conway and Sloane's algorithm for lexicographic codes [6], and two methods that synthesize new coverings from preexisting ones. Using these new methods, together with results in the literature, we build tables of upper bounds on C(v,k,t) for v ⩽ 32, k ⩽ 16, and t ⩽ 8. © 1995 John Wiley & Sons, Inc.
A remark on the uniqueness of embeddings of linear spaces into desarguesian projective planes
Authors: Metsch Klaus
Published: June 2007

Suppose that q ⩾ 2 is a prime power. We show that a linear space with a(q + 1)2 + (q + 1) points, where a ⩾ 0.763, can be embedded in at most one way in a desarguesian projective plane of order q. © 1995 John Wiley & Sons, Inc.
Smoothness versus skewness in block designs with an application to tournaments
Authors: Robinson David G.
Published: June 2007

The quadratic residue designs over GF(7) and GF(11) are shown to be the only quasismooth skew (Hadamard) designs, thus setting a conjecture of Herzog and Reid concerning the existence of so‐called “nearly triply regular” tournaments. © 1995 John Wiley & Sons., Inc.
A. translation of J. X. Lu's “an existence theory for resolvable balanced incomplete block designs”
Authors: Lee Therese C. Y. , Furino Steven C.
Published: June 2007

In 1984, J. X. Lu proved the following statement. Given any k and λ, there exists a constant c(k, λ) such that an RB[v,k,λ] exists for all v > c(k,λ) satisfying the usual necessary conditions. Lu's paper was written in Chinese and, unfortunately, its accessibility is limited. We have translated Lu's paper into English and have also given a new interpretation of his constructions for resolvable block designs. © 1995 John Wiley & Sons, Inc.
Calibration of PRECIS in employing future scenarios in Bangladesh
Authors: Nazrul Islam Md. , Rafiuddin M. , Ahmed Ahsan Uddin , Kolli Rupa Kumar
Published: June 2007

Providing Regional Climates for Impacts Studies (PRECIS) is a regional climate model, which is used for the simulation of regional‐scale climatology at high resolution (i.e. 50‐km horizontal resolution). The calibration of rainfall and temperature simulated by PRECIS is performed in Bangladesh with the surface observational data from the Bangladesh Meteorological Department (BMD) for the period 1961–1990. The Climate Research Unit (CRU) data is also used for understanding the performance of the model. The results for the period 1961–1990 are used as a reference to find the variation of PRECIS‐projected rainfall and temperature in 2071, in and around Bangladesh, as an example. Analyses are performed using the following two methods: (1) grid‐to‐grid and (2) point‐to‐point analyses. It is found that grid‐to‐grid analysis provides overestimation of PRECIS in Bangladesh because of downscaling of observed data when gridded from asymmetric low‐density data network of BMD. On the other hand, model data extracted at observational sites provide better performance of PRECIS. The model overestimates rainfall in dry and pre‐monsoon periods, whereas it underestimates it in the monsoon period. Overall, PRECIS is found to be able to estimate about 92% of surface rainfall. Model performance in estimating rainfall increases substantially with the increase in the length of time series of datasets. Systematic cold bias is found in simulating the annual scale of the surface temperature. In the annual scale, the model underestimates temperature of about 0.61 °C that varies within a range of + 1.45 °C to − 3.89 °C in different months. This analysis reveals that rainfall and temperature will be increased in Bangladesh in 2071. On the basis of the analyses, look‐up tables for rainfall and temperature were prepared in a bid to calibrate PRECIS simulation results for Bangladesh. The look‐up tables proposed in this analysis can be employed in the application of the projected rainfall and temperature in different sectors of the country. These look‐up tables are useful only for the calibration of PRECIS simulation results for future climate projection for Bangladesh. Copyright © 2007 Royal Meteorological Society
A pre‐deforestation pollen‐climate calibration model for New Zealand and quantitative temperature reconstructions for the past 18 000 years BP
Authors: Wilmshurst Janet M. , McGlone Matt S. , Leathwick John R. , Newnham Rewi M.
Published: June 2007

Quantification of modern pollen rain–vegetation–climate relationships in New Zealand has been complicated by human destruction of at least 75% of the original forest cover since ca. 750 years BP, causing contemporary pollen rain over large areas to bear little resemblance to the pre‐human vegetation. We use a pre‐deforestation pollen database to circumvent this complication. The relationships between the pre‐deforestation pollen assemblages and six climatic variables were explored using principal components analysis and constrained regressions (redundancy analyses). Quantitative estimates of the most significant climate variable (mean annual temperature) were made at seven lowland to montane fossil pollen sites from throughout New Zealand using the modern analogue technique and a transfer function. These showed an initial increase in mean annual temperature after 18 000 cal. yr BP, a cooling at the time of the Antarctic Cold Reversal (centred on 13 500 cal. yr BP) and continuation of warming from ca. 12 000 cal. yr BP across the Younger Dryas chronozone, reaching a Holocene thermal optimum that may have been between 1.5 and 3°C warmer than present and lasted from 9000 to 7000 cal. yr BP depending on the site. Cooling to present‐day temperatures was well advanced by 4000–3000 cal. yr BP. Copyright © 2007 John Wiley & Sons, Ltd.