bluuebunny/crossref_metadata_2025 huggingface dataset:
Nortricyclyl‐ and Norbornenyl‐Acylrhodium Complexes from the Reaction of Norbornadiene Rhodium(I) Complexes with o‐(Diphenylphosphanyl)benzaldehyde
Authors: El Mail Rachad , Garralda María Angeles , Hernández Ricardo , Ibarlucea Lourdes , Pinilla Elena , Torres María Rosario , Zarandona Malkoa
Published: April 2005

[{Rh(Nbd)Cl}2] (Nbd = norbornadiene) reacts with o‐(diphenylphosphane)benzaldehyde in benzene solution to give the rhodium(III) complex [Rh(Cl)(C7H9){o‐PPh2(C6H4CO)}]n (1), where C7H9 is a nortricyclyl (Ntyl) group. Complex 1 reacts with various bidentate N‐donors, such as biacetyldihydrazone, 2,2'‐bipyridine, 8‐aminoquinoline, 2‐(aminomethyl)pyridine, or pyridine, to afford nortricyclyl [Rh(Cl){o‐PPh2(C6H4CO)}(Ntyl)(NN)] complexes. The presence of the nortricyclyl group and the structure of the complexes have been confirmed by NMR spectroscopy and, in one case, by single‐crystal X‐ray diffraction. Nortricyclyl complexes containing bidentate N‐donors are also formed by the reaction in benzene of PPh2(o‐C6H4CHO) with the corresponding [Rh(Cl)(Nbd)(NN)] compounds prepared “in situ”. [Rh(Cl)(Nbd)(bipy)] prepared “in situ” reacts with PPh2(o‐C6H4CHO) in methanol to give the complex [Rh(Cl){o‐PPh2(C6H4CO)}(C7H9)(bipy)], where C7H9 is a norbornenyl (Nbyl) group. This compound has been fully characterized by NMR spectroscopy. A proposal for the selective production of the norbornenyl and the nortricyclyl derivatives is presented. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Novel Supramolecular Frameworks Self‐Assembled from a Two‐Dimensional Polymeric Network: Synthesis and Crystal Structure of a Macrocyclic Organotin(IV) Complex
Authors: Ma Chunlin , Han Yinfeng , Zhang Rufen , Wang Daqi
Published: April 2005

The two‐dimensional polymer [nBu2Sn(O2CC6H4)]4 has been synthesized by the self‐assembly of di‐n‐butyltin oxide and 4‐carboxyphenylboronic acid. The X‐ray crystal structure shows that the metal ions display a trigonal bipyramidal coordination geometry to bind the endocyclic oxygen atom. Intermolecular π–π stacking interactions between adjacent phenyl groups of the ligand cause the self‐assembly into a 1D chain. In this chain one oxygen atom of the carboxylate group binds to one [nBu2Sn(O2CC6H4)]4 unit to give rise to a 2D architecture. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Stereoisomerism in Pentaerythritol‐Bridged Cyclotriphosphazene Tri‐Spiranes: Spiro and Ansa 1,3‐Propanediyldioxy Disubstituted Derivatives
Authors: Uslu Aylin , Coles Simon J. , Davies David B. , Eaton Robert J. , Hursthouse Michael B. , Kılıç Adem , Shaw Robert A.
Published: April 2005

In each spirane structure in Figure 1 on p. 1043 of the original article[1] the spiro atom of the left‐hand cyclophosphazene ring should be phosphorus rather than nitrogen; the correct Figure 1 is shown below.
Synthesis and Characterisation of New Iridium Complexes with the (4S)‐2‐[2‐(Diphenylphosphanyl)phenyl]‐4‐isopropyl‐1,3‐oxazoline Ligand That Catalyse Asymmetric Michael Reactions (Eur. J. Inorg. Chem. 9/2005)
Authors: Carmona Daniel , Ferrer Joaquina , Lorenzo Mónica , Lahoz Fernando J. , Dobrinovitch Isabel T. , Oro Luis A.
Published: April 2005

The cover picture shows the structure of a new chiral iridium(I) complex with the (4S)‐2‐[2‐(diphenylphosphanyl)phenyl]‐4‐isopropyl‐1,3‐oxazoline ligand [(S)‐PN] that catalyses the asymmetric Michael addition of keto or cyano esters to α,β‐unsaturated carbonyl compounds. The hydrido(enolato) species, [IrH(NCCHCO2R2){(S)‐PN}2]Cl, postulated as catalytic intermediates, have also been isolated and spectroscopically characterised. Details are discussed in the article by D. Carmona et al. on p. 1657 ff.
Variable selection and interpretation in correlation principal components
Authors: Al‐Kandari Noriah M. , Jolliffe Ian T.
Published: April 2005

Principal component analysis (PCA) is a dimension‐reducing tool that replaces the variables in a multivariate data set by a smaller number of derived variables. Dimension reduction is often undertaken to help in interpreting the data set but, as each principal component usually involves all the original variables, interpretation of a PCA can still be difficult. One way to overcome this difficulty is to select a subset of the original variables and use this subset to approximate the principal components. This article reviews a number of techniques for choosing subsets of the variables and examines their merits in terms of preserving the information in the PCA, and in aiding interpretation of the main sources of variation in the data. Copyright © 2005 John Wiley & Sons, Ltd.
Unnatural landscapes in ecology: generating the spatial distribution of brine spills
Authors: Jager Henriette I. , Efroymson Rebecca A. , Sublette Kerry L. , Ashwood Tom L.
Published: April 2005

Quantitative tools are needed to evaluate the ecological effects of increasing petroleum production. In this article, we describe two stochastic models for simulating the spatial distribution of brine spills on a landscape. One model uses general assumptions about the spatial arrangement of spills and their sizes; the second model distributes spills by siting rectangular well complexes and conditioning spill probabilities on the configuration of pipes. We present maps of landscapes with spills produced by the two methods and compare the ability of the models to reproduce a specified spill area. A strength of the models presented here is their ability to extrapolate from the existing landscape to simulate landscapes with a higher (or lower) density of oil wells. Published in 2005 by John Wiley & Sons, Ltd.
Possibilities of Mass Spectrometry and Tandem‐Mass Spectrometry in the Analysis of Cellulose Ethers
Authors: Mischnick Petra , Niedner Wulff , Adden Roland
Published: April 2005

The investigation of the substituent pattern of cellulose and starch ethers and esters on various structural levels as in the glucosyl unit, along the polymer chain, and over the polymer molecules, still is a very challenging task.

By means of mass spectrometric methods as ESI‐MS or MALDI‐TOF‐MS the composition of oligosaccharide mixtures which represent the substituent distribution in the original polymer can principally be determined. However, to obtain reliable quantitative data mass spectra must be recorded under appropriate instrumental conditions and after special sample preparation While O‐methyl/O‐methyl‐d3‐oligosaccharides give representative data with the mentioned MS techniques and FAB‐MS as well, hydroxyalkyl ethers require labelling with a quaternary ammonium tag and MALDI‐TOF‐MS to prevent discrimination of lower substituted oligosaccharides. In this way, information on the neighbourhood of glucosyl units in the polymer chain is available which – together with the monomer composition – is a valuable parameter to describe a random or a heterogeneous pattern with regions of local higher densities of substituents compared to the random model, a regular distribution, or a block‐like substituent pattern, i.e. a more clustered localisation of substiuents in the polymer chain. In addition, tandem‐mass spectrometry (ESI‐MSn) allows to gain further insight in the composition of isomeric oligosaccharide derivatives of the same m/z ratio and to calculate the complete monomer composition of methyl celluloses.
Structure Determination of Cellulose Esters via Subsequent Functionalization and NMR Spectroscopy
Authors: Liebert Tim , Hussain Muhammad A. , Heinze Thomas
Published: April 2005

New paths for the fast and reliable analysis of cellulose esters (CE) via subsequent functionalization and 1H NMR spectroscopy were studied. Perpropionylation of the CE is an inexpensive and efficient method. For cellulose diacetates used as representative ester well resolved 1H NMR spectra were obtained, which can be used for the calculation of the over all degree of substitution (DS) and the partial DS values at position 2, 3, and 6. No transesterification occurs during the subsequent acylation and a standard deviation of S2 = 1.32 x 10−4 was found for a series of experiments. In case of more complex ester structures especially with extended aliphatic moieties per‐4‐nitrobenzoylation need to be applied prior to NMR measurements. The spectra obtained can be completely assigned and applied for the calculation of DS values.
Endoglucanase Degradation and Enzyme‐Aided Characterization of Cellulose Acetates
Authors: Saake Bodo , Altaner Clemens , Lee Soo‐Jung , Puls Jürgen
Published: April 2005

Endoglucanases were used as a selective tool to determine the substituent distribution along the chains of partially substituted cellulose acetates. Unsubstituted segments are intensively fragmented while highly substituted segments are only slightly degraded or not affected at all. Two different procedures were developed to perform a preparative separation of the fragments by size exclusion chromatography. One system is based on a direct separation of the fragmentation products using pyridine : water (9 : 1) as an eluent. The isolated fragments can be analysed regarding to their DS values by ATR/FTIR spectroscopy or by hydrolysis and HPLC. The second system is based on deutero‐acetylation of endoglucanase fragmented samples. The complete acetylation of all OH groups enables a chromatographic separation in chloroform. Afterwards the isolated fragments can be analysed regarding to their partial DS values by 1H‐NMR spectroscopy.
NMR investigation of hydrogen bonding and 1,3‐tautomerism in 2‐(2‐hydroxy‐5‐substituted‐aryl) benzimidazoles
Authors: Sridharan V. , Saravanan S. , Muthusubramanian S. , Sivasubramanian S.
Published: April 2005

The 1,3‐tautomerism associated with 2‐(2‐hydroxy‐5‐substituted‐aryl)benzimidazoles was studied in different solvents. The effect of hydrogen bonding involving the hydroxyl group of the 2‐aryl ring on the tautomerism was investigated using NMR spectroscopy. The influence of the solvent concentration on 2‐(2‐hydroxy‐5‐chloroaryl)benzimidazole was studied in acetone‐d6 and DMSO‐d6. Copyright © 2005 John Wiley & Sons, Ltd.
1H and 13C NMR identification of unexpected 3,4‐dihydroquinoxalines in the syntheses of 1,5‐benzodiazepine derivatives
Authors: Tjiou E. M. , Lhoussaine E. G. , Virieux D. , Fruchier A.
Published: April 2005

The reaction between o‐phenylenediamines, dehydroacetic acid and aromatic aldehydes is shown to give not only the expected 1,5‐benzodiazepine derivative but also a 3,4‐dihydroquinoxaline, the structure of which was determined by its 1H and 13C 1D and 2D NMR spectra. Copyright © 2005 John Wiley & Sons, Ltd.
A concave‐cost production planning problem with remanufacturing options
Authors: Yang Jian , Golany Boaz , Yu Gang
Published: April 2005

We focus on the concave‐cost version of a production planning problem where a manufacturer can meet demand by either producing new items or by remanufacturing used items. Unprocessed used items are disposed. We show the NP‐hardness of the problem even when all the costs are stationary. Utilizing the special structure of the extreme‐point optimal solutions for the minimum concave‐cost problem with a network flow type feasible region, we develop a polynomial‐time heuristic for the problem. Our computational study indicates that the heuristic is a very efficient way to solve the problem as far as solution speed and quality are concerned. © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2005
Matchings in 3‐vertex‐critical graphs: The even case
Authors: Ananchuen Nawarat , Plummer Michael D.
Published: April 2005

A subset of vertices D of a graph G is a dominating set for G if every vertex of G not in D is adjacent to one in D. The cardinality of any smallest dominating set in G is denoted by γ(G)and called the domination number of G. Graph G is said to be γ‐vertex‐critical if γ(G − v) < γ(G), for every v vertex in G. Comparatively little is known to date about the structure of γ‐vertex‐critical graphs, even in the case when γ = 3. In the present article, we begin the study of matchings in 3‐vertex‐critical graphs. In particular, we show that any 3‐vertex‐critical graph on an even number of vertices, which has no induced subgraph isomorphic to the bipartite graph K1,5 much have a perfect matching, whereas 3‐vertex‐critical even graphs in general need not contain such a matching. We close with a conjecture. © 2005 Wiley Periodicals, Inc. NETWORKS, Vol. 45(4), 210–213 2005
Preparation and characterization of rigid poly (vinyl chloride)/MMT nanocomposites
Authors: Chen Cheng‐Ho , Teng Chih‐Chun , Yang Chien‐Hsin
Published: April 2005

In this article, a Haake torque rheometer equipped with an internal mixer is used to study the influence of the amount of sodium montmorillonite (Na+‐MMT) and organically modified MMT (O‐MMT) on the characteristics of rigid poly (vinyl chloride) (PVC)/Na+‐MMT and PVC/O‐MMT nanocomposites, respectively. It is observed that the fusion time and temperature of the rigid PVC/Na+‐MMT nanocomposites are decreased with increasing the amount of Na+‐MMT. On the contrast, the fusion time and temperature of the rigid PVC/O‐MMT nanocomposites are increased with increasing the amount of O‐MMT. Results of X‐ray diffraction (XRD) and transmission electron microscope (TEM) indicate that MMT is partially encapsulated and intercalated in the rigid PVC/Na+‐MMT nanocomposites. However, results of XRD and TEM show MMT is partially intercalated and exfoliated in the rigid PVC/O‐MMT nanocomposites. Tensile strength, yield strength, and elongation at break of the rigid PVC/MMT (including PVC/Na+‐MMT and PVC/O‐MMT) nanocomposites were improved simultaneously with adding 1–3 wt % Na+‐MMT or O‐MMT with respect to those of pristine PVC. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1465–1474, 2005
Reversal of some viral IL‐6 electrostatic properties compared to IL‐6 contributes to a loss of alpha receptor component recruitment
Authors: Perret David , Rousseau François , Tran Vinh , Gascan Hugues
Published: April 2005

Human interleukin‐6 (hIL‐6) is a pleiotropic mediator of activation and proliferation across a large number of different cell types. Human herpesvirus‐8 (HHV‐8) has been associated with classical and AIDS‐related Kaposi's sarcoma (KS). HHV‐8 encodes viral IL‐6 (vIL‐6), a functional homolog of human interleukin‐6, that promotes the growth of KS and of some lymphoma cells. Signaling induced by human IL‐6 requires recruitment of the glycoprotein gp130, which acts as the signal transducing chain, and of IL‐6Rα, which is necessary for cognate recognition and high affinity receptor complex formation. In contrast, the formation of a functional complex between vIL‐6 and gp130 does not require the presence of IL‐6Rα. The physico‐chemical properties of vIL‐6 have been analyzed and compared to those of hIL‐6 and of the receptor chains, gp130 and IL‐6Rα. Interaction sites on vIL‐6 involve more hydrophobic residues than those of hIL‐6. The electrostatic fields induced by vIL‐6 and IL‐6Rα are repulsive and prevent interaction between vIL‐6 and IL‐6Rα, whereas the electrostatic field induced by hIL‐6 steers the complex formation with IL‐6Rα. Subsequently, electrostatic binding free energy in the vIL‐6/IL‐6Rα complex is destabilizing, whereas it is stabilizing in the complex comprising hIL‐6. These properties result from charge reversals between viral and human IL‐6, an unusual phenomenon of amino acid substitutions within a homologous protein family. This suggests a selection pressure for vIL‐6 to by‐pass the IL‐6Rα control of host defense against virus infection. This selection pressure has yielded the reversal of electrostatic properties of vIL‐6 when compared to hIL‐6. Proteins 2005. © 2005 Wiley‐Liss, Inc.
Application of InChI to curate, index, and query 3‐D structures
Authors: Prasanna M.D. , Vondrasek Jiri , Wlodawer Alexander , Bhat T.N.
Published: April 2005

The HIV structural database (HIVSDB) is a comprehensive collection of the structures of HIV protease, both of unliganded enzyme and of its inhibitor complexes. It contains abstracts and crystallographic data such as inhibitor and protein coordinates for 248 data sets, of which only 141 are from the Protein Data Bank (PDB). Efficient annotation, indexing, and querying of the inhibitor data is crucial for their effective use for technological and industrial applications. The application of IUPAC International Chemical Identifier (InChI) to index, curate, and query inhibitor structures HIVSDB is described. Proteins 2005. Published 2005 Wiley‐Liss, Inc.
Recognizing protein folds by cluster distance geometry
Authors: Crippen Gordon M.
Published: April 2005

Cluster distance geometry is a recent generalization of distance geometry whereby protein structures can be described at even lower levels of detail than one point per residue. With improvements in the clustering technique, protein conformations can be summarized in terms of alternative contact patterns between clusters, where each cluster contains four sequentially adjacent amino acid residues. A very simple potential function involving 210 adjustable parameters can be determined that favors the native contacts of 31 small, monomeric proteins over their respective sets of nonnative contacts. This potential then favors the native contacts for 174 small, monomeric proteins that have low sequence identity with any of the training set. A broader search finds 698 small protein chains from the Protein Data Bank where the native contacts are preferred over all alternatives, even though they have low sequence identity with the training set. This amounts to a highly predictive method for ab initio protein folding at low spatial resolution. Proteins 2005;. © 2005 Wiley‐Liss, Inc.
Tryptophan to phenylalanine substitutions allow differentiation of short‐ and long‐range conformational changes during denaturation of goat α‐lactalbumin
Authors: Vanhooren Ann , Chedad Allel , Farkas Viktor , Majer Zsuzsa , Joniau Marcel , Van Dael Herman , Hanssens Ignace
Published: April 2005

To test the occurrence of local particularities during the unfolding of Ca2+‐loaded goat α‐lactalbumin (GLA) we replaced Trp60 and ‐118, either one or both, by Phe. In contrast with alternative studies, our recombinant α‐lactalbumins are expressed in Pichia pastoris and do not contain the extra N‐terminal methionine. The substitution of Trp60 leads to a reduction of the global stability. The effect of the Trp118Phe substitution on the conformation and stability of the mutant, however, is negligible. Comparison of the fluorescence spectra of these mutants makes clear that Trp60 and ‐118 are strongly quenched in the native state. They both contribute to the quenching of Trp26 and ‐104 emission. By the interplay of these quenching effects, the fluorescence intensity changes upon thermal unfolding of the mutants behave very differently. This is the reason for a discrepancy of the apparent transition temperatures derived from the shift of the emission maxima (Tm,Fl λ) and those derived from DSC (Tm,DSC). However, the transition temperatures derived from fluorescence intensity (Tm,Fl int) and from DSC (Tm,DSC), respectively, are quite similar, and thus, no local rearrangements are observed upon heat‐induced unfolding. At room temperature, the occurrence of specific local rearrangements upon GdnHCl‐induced denaturation of the different mutants is deduced from the apparent free energies of their transition state obtained from stopped‐flow fluorescence measurements. By ϕ‡‐value analysis it appears that, while the surroundings of Trp118 are exposed in the kinetic transition state, the surroundings of Trp60 remain native. Proteins 2005. © 2005 Wiley‐Liss, Inc.
Spectroscopic and DFT studies of donor–acceptor molecules containing phenylquinoline and phenothiazine moieties in various redox states
Authors: Ponce Ortiz R. , Malavé Osuna R. , Ruiz Delgado M. C. , Casado J. , Jenekhe S. A. , Hernandez V. , Lopez Navarrete J. T.
Published: April 2005

We report the ultraviolet (UV)‐Vis, Fourier transform‐infrared (FT‐IR), and FT‐Raman spectroscopic study of an electrogenerated chemiluminescence (ECL) emitting compound containing two electron‐accepting phenylquinoline end groups covalently attached to an electron‐donating 10‐methylphenothiazine central moiety. The optimized molecular geometry of the neutral compound as determined from quantum chemical density functional theory (DFT)//B3LYP/3‐21G* calculations shows that the phenyl groups appended onto the quinolines are twisted by ≈62° from these moieties. The sulfur atom is also tilted with respect to the plane defined by the phenyl rings of the phenothiazine, in both the neutral and singly oxidized species. The highest occupied molecular orbitals (HOMO) and lowest unoccupied molecular orbitals (LUMO) of the neutral systems partially overlap, so that the lowest‐energy visible absorption band implies a certain degree of charge transfer from the phenothiazine toward the phenylquinolines. In contrast, the removal of the first electron mainly affects the structure and equilibrium charge distribution of the phenothiazine, and much less in those of the quinolines. In addition, the DFT//UB3LYP/3‐21G* topologies of the molecular orbitals around the bandgap region of the radical cation reveal no molecular orbital overlap between the two types of constituent building blocks, thus inhibiting the delocalization of the injected positive charge over the whole molecule. This feature could be in line with the ability of this system to generate localized radical ions capable of displaying chemiluminescence upon annihilation, as previously observed experimentally. The UV‐Vis and FT‐Raman spectra of the singly oxidized species generated upon treatment with FeCl3 in CH2Cl2 solution have also been recorded. The experimental data were interpreted with the help of DFT calculations. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Control of the Molecular Alignment Inside Liquid‐Crystal Droplets by Use of Laser Tweezers
Authors: Murazawa Naoki , Juodkazis Saulius , Matsuo Shigeki , Misawa Hiroaki
Published: April 2005

Here, we demonstrate how the light‐induced birefringence due to the dipole molecular realignment and anisotropic polarizability of a nematic liquid crystal inside a droplet changes the droplet’s radial (and thus optically isotropic) structure into a birefringent one. This intensity‐dependent change of birefringence can be understood in terms of the anisotropic polarizability and orientational optical nonlinear effect. Birefringence induced by laser tweezers changes the momentum of the passing light. In turn, for the circularly polarized tweezers, this change generates an angular momentum change large enough to spin micrometer‐sized droplets. For the linearly polarized tweezers, the molecular ordering generates momentum, which laterally displaces the droplet. It is shown that the optical nonlinearity can be “large” enough to have mechanical (ponderomotive) implications, that is, it allows control of the movement and position of micro‐objects with submicrometer resolution. The optically induced molecular alignment controlled by the polarization and power of the laser tweezers allows one to actuate, rotate, and translate objects which are up to 103–104 times larger than the constituent molecules themselves.
Flow Focusing: A Versatile Technology to Produce Size‐Controlled and Specific‐Morphology Microparticles
Authors: Martín‐Banderas Lucía , Flores‐Mosquera María , Riesco‐Chueca Pascual , Rodríguez‐Gil Alfonso , Cebolla Ángel , Chávez Sebastián , Gañán‐Calvo Alfonso M.
Published: April 2005

The Flow Focusing platform is especially advantageous for micro‐ and nanoparticle production. This versatile technique is amenable to designing the size, surface treatment and internal topology of the particles; mechanical stresses are minimal—an optimal feature for the manipulation of delicate substances. Multiplexing and high‐rate production are readily implemented. Adaptive operational design can lead, in one single step, to finely tuned microcapsules encasing different products within a targeted morphology. This achievement is of great significance for most microcapsule applications in the biosciences (for example, drug delivery, cell encapsulation, and the production of bead arrays).
Thrombolysis Nurses: Time for Review
Authors: Jones Ian
Published: April 2005

Thrombolysis remains the most popular means of reperfusion following an acute ST-elevation myocardial infarction in the United Kingdom today. There is a wealth of evidence to support the early provision of thrombolysis care and a number of models of care delivery have been proposed to reduce the time delay from admission to hospital to administration of thrombolytic therapy. The movement of this treatment from the coronary care unit to the emergency department in association with the employment of specialist cardiac nurses has been associated with some time reductions. However the quality of evidence to support the employment of specialist cardiac nurses working outside the coronary care unit is limited. The author provides an overview of the main literature in this area outlining the models of care in operation and argues that there are lessons to be learned for future nursing research.
New dates of musk-ox (Ovibos moschatus) remains from northwest Greenland
Authors: Bennike Ole , Andreasen Claus
Published: April 2005

Northwest Greenland formerly supported a population of musk-ox (Ovibos moschatus). Radiocarbon dating of musk-ox remains collected on the terrain surface and from archaeological sites has yielded Late Holocene ages, indicating that the species was a late immigrant to this part of Greenland. Musk-ox arrived at a time when Greenland was uninhabited, and the species had at least several hundred years to expand and spread south, before the Late Dorset people arrived and began to hunt. The main reason that the species did not disperse south to West Greenland was probably because of the barrier presented by Melville Bugt, which was heavily glaciated in the Late Holocene. However, if there had been a longer period of time before hunting of the musk-ox occurred, there would have been an enhanced likelihood that chance dispersal south could have taken place.
Joseph Shackleton in Iceland, 1861
Authors: Stone Ian R.
Published: April 2005

Joseph Shackleton, a member of the same family as Sir Ernest Shackleton, visited Iceland with two friends in 1861. They travelled in Arcturus, a Danish vessel that ran a scheduled service in summer. They visited the two main ‘attractions,’ namely Thingvellir and the geysers. Shackleton's manuscript account of the trip indicates that tourism was developed by such an early date and that the infrastructure for it was in place and efficient. His account also provides interesting information concerning contemporary Iceland.
German Antarctic Expedition, 1873–74
Authors: Hattersley-Smith Geoffrey
Published: April 2005

In late February/early March 1874, the members of Eduard Dallman's German ‘Grönland’ Expedition erected a commemorative plaque at Potter Cover, King George Island, South Shetland Islands. This historic monument was previously noted by a four-man party in 1949.
Gordon de Quetteville Robin
Authors: Drewry David J.
Published: April 2005

Gordon de Quetteville Robin died on 21 September 2004 at the age of 83. During his life he contributed significantly and innovatively to his own academic subject of glaciology and, persuaded of the high value of cooperation between national groups at an early age, promoted actively and effectively the cause of international collaboration in Antarctica. He raised the profile and contribution to polar research of the Scott Polar Research Institute, University of Cambridge, to a new peak during his influential directorship between 1958 and 1982.
Settlement and unsettlement in Aotearoa/New Zealand and Antarctica
Authors: Dodds Klaus J. , Yusoff Kathryn
Published: April 2005

This paper is concerned with Aotearoa/New Zealand's changing relationship to Antarctica, and the Ross Dependency in particular. Through a consideration of post-colonial theory in the Ross Dependency, it is argued that a productive dialogue about the cultural politics of mainland Aotearoa/New Zealand can be opened up. After some reflections on the post-1945 political and cultural trajectory of the country, attention is given to the place of the Maori and their involvement in the polar continent and Southern Ocean. The adoption of Maori place-names on New Zealand maps of the Ross Dependency is considered further because it helps to illuminate the country's awkward and incomplete post-colonial transformation. Arguably, such an adoption of Maori place-names in Antarctica contributes to a vision of bicultural harmony. However, this is not a view shared by all observers. Developments affecting the crown agency Antarctica New Zealand, alongside recent heritage projects, are scrutinised further in order to consider how Maori–Pakeha relations influence and define contemporary understandings of New Zealand's presence in Antarctica. Finally, the paper briefly contemplates how a trans-Tasman dialogue with Australian scholars might enable further analysis into how geographically proximate settler colonies engage with Antarctica and their associated territorial claims to the continent and surrounding ocean.
Spatial organization and diet of the leopard cat (Prionailurus bengalensis) in north‐central Thailand
Authors: Grassman Lon I. , Tewes Michael E. , Silvy Nova J. , Kreetiyutanont Kitti
Published: April 2005

The leopard catPrionailurus bengalensisis a relatively common, small felid ranging throughout Asia. During the past 15 years the natural history of leopard cats has been the topic of five studies; however, the mean sample size of study animals has been low (x = 6.8, range 4–10). We report on the most comprehensive study of leopard cats to date. Between June 1999 and February 2003, 20 leopard cats (14 males and six females) were radio‐collared and tracked from 3 to 20 months in Phu Khieo Wildlife Sanctuary, Thailand. Spatial organization of the leopard cats was characterized as weakly territorial with similar intrasexual range sizes and minimal seasonal variation. Mean (±sd) annual home‐range (95% minimum convex polygon) size for males was 12.4 km2(n= 1211 locations, ± 7.1, range 2.2–28.9), whereas females exhibited a mean home‐range size of 14 km2(n= 470, ± 12.2, range 4.4–37.1). Core area (50% minimum convex polygon) averaged 2.0 km2, and the mean 1‐day movement was 1298 m (± 981, range 35–8653). Habitat use was generally in proportion to occurrence, and the mean activity (52%) was arrhythmic with crepuscular and nocturnal peaks. Analysis of scats indicated that murids dominated leopard cat diet.
Measures of dung bolus size for known‐age African elephants (Loxodonta africana): implications for age estimation
Authors: Morrison Thomas A. , Chiyo Patrick I. , Moss Cynthia J. , Alberts Susan C.
Published: April 2005

The availability of a population of mostly known‐age African elephants Loxodonta africana from Amboseli National Park, Kenya, provided a unique opportunity to assess the use of dung bolus diameter for estimating age. A predictive equation for estimating dung bolus diameters from elephants of known age was derived and was found to follow the typical growth pattern exhibited by changes in shoulder height and foot length. The relationship between measurements of dung bolus and age was particularly strong when growth rates were high (age 0–25 years). The dung bolus growth curve from Amboseli elephants was similar to that derived from another wild population of African elephants, suggesting that dung bolus diameter can be used to assess age structure in areas where it is impossible to construct independent prediction curves of age and dung bolus.
Seasonal changes in the testis, accessory glands and ejaculate characteristics of the southern hairy‐nosed wombat, Lasiorhinus latifrons (Marsupialia: Vombatidae)
Authors: Taggart D. A. , Shimmin G. A. , Ratcliff J. R. , Steele V. R. , Dibben R. , Dibben J. , White C. , Temple‐Smith P. D.
Published: April 2005

Most mammals exhibit seasonal variation in the reproductive capacity of one or both sexes. While the female southern hairy‐nosed wombat Lasiorhinus latifrons is a known seasonal breeder, the extent of seasonality in the male has not been documented. To examine this, gross body measurements including scrotal diameter and the dimensions of the accessory gland bulge were recorded and male reproductive tracts were examined between 1993 and 2000. Testes, epididymides and accessory glands from all males were dissected free of connective tissue and weighed. In addition, matched semen samples were collected over four time points in 2000 corresponding to the breeding season (September), immediately post‐breeding season (November), during the non‐breeding season (January), and immediately before the onset of the next breeding season (June) as determined from female reproductive status. Semen was collected by electro‐ejaculation and analysed for volume, sperm number and motility characteristics. Ejaculate volume, total ejaculate sperm number, percentage motile sperm, and the sperm motility rating and index were all significantly elevated in September and significantly lower in November and January. This correlated with a significant increase in body weight, peri‐cloacal gland width, and the weights of the prostate, Cowper's glands, urethral bulb and crus penis. The data confirm that male reproduction in the southern hairy‐nosed wombat, like that of the female, is highly seasonal with a peak in reproductive capacity occurring in August–September and a reduction by November.
Near‐simultaneous plasma structuring in the midlatitude and equatorial ionosphere during magnetic superstorms
Authors: Basu S. , Basu Su. , Groves K. M. , MacKenzie E. , Keskinen M. J. , Rich F. J.
Published: April 2005

Near simultaneous formation of ionospheric plasma density structures at middle and equatorial latitudes during the intense magnetic storms of October 29–31, 2003, July 15, 2000, and March 30–31, 2001 is investigated. The evolution of these structures is explored by measuring amplitude scintillation of satellite signals at 250 MHz, determining zonal irregularity drifts and by detecting equatorial plasma bubbles with DMSP satellites. During abrupt decreases of SYM‐H (1‐minute resolution Dst) that signify the penetration of high latitude electric fields, an impulsive onset of scintillation occurs at Hanscom AFB (HAFB), a sub‐auroral location, as well as in the equatorial region where the early evening period corresponds to the time of scintillation onset at midlatitudes. The onset of equatorial scintillation is delayed from that at midlatitudes by about 20 minutes which can be accounted for by considering instantaneous electric field penetration and plasma instability growth time of equatorial irregularities.
Simulation of ULF field‐aligned currents generated by HF heating of the ionosphere
Authors: Streltsov A. V. , Lotko W. , Milikh G. M.
Published: April 2005

This paper presents results from a numerical study of the generation of magnetic field‐aligned currents with a perpendicular scale size of the order of 10 km and a magnitude of a few μA/m2 at 100‐km altitude by the ionospheric feedback instability triggered and controlled by the heating of the ionospheric E layer with a powerful HF transmitter. Simulations reveal that the development of the feedback instability inside the global magnetospheric resonator significantly depends on both the conductivity of the heated ionosphere and that of the conjugate ionosphere. Investigations of different temporal modes of the heater operation show that the heating has a maximum effect on the instability growth rate when it is modulated with an eigenfrequency of the coupled magnetosphere‐ionosphere system. This frequency is sensitive to the ionospheric parameters, in particular to the magnitude of the background electric field inside the ionospheric E layer, and it can be 10 times lower that the eigenfrequency of shear Alfvén waves standing along the magnetic field lines between the ionospheres.
Complex evolution of paleolacustrine systems on Mars: An example from the Holden crater
Authors: Pondrelli M. , Baliva A. , Di Lorenzo S. , Marinangeli L. , Rossi A. P.
Published: April 2005

The ∼150 km wide Holden crater lies in an area characterized by high density of valley networks implying conditions conducive to forming of water‐related environments. We undertook geological mapping and a stratigraphic survey in order to probe the evolution of water‐related landforms and their paleoenvironmental implications. Our investigations lead us to propose that the Holden area was subjected to a “wet” lacustrine phase of Hesperian age and an “icy” phase during the Amazonian. Deltaic, coastal, and lacustrine environments occurred during the “wet” phase, some displaying a cyclic depositional pattern presumably related to autogenic processes. Water was delivered to the basin by the Uzboi Vallis and by surface runoff channels from a series of drainage basins along the crater walls. Fan delta geometries and coastal onlap enabled estimation of major water levels. Two levels of major stand of the water have been recognized, possibly reflecting allogenic controls. Geologic units related to this “wet” lacustrine phase were subsequently eroded by glacial abrasion and plucking and were disconformably overlain by glacial deposits of Amazonian age, defining an “icy” phase. These features are consistent with a warm‐based glacier entering the Holden crater through the wide Uzboi Vallis to form a proglacial lake in the central part of the crater. Changes in sedimentary units reflect changes of depositional environments probably connected with climatic variation.
Approximate estimates of fracture speeds for dry slab avalanches
Authors: McClung D. M.
Published: April 2005

Dry slab avalanches release by propagating shear fractures. It has been suggested that slab wave or fracture speed on horizontal terrain is consistent with the propagation of a flexural wave in the slab. In this note, an alternate proposal is made. Namely, it is proposed that the fracture speed is consistent with dynamic crack propagation speeds from other materials. The theory is compared with an in situ measurement of speed associated with shear fracture propagation in a weak snow pack layer sensed by geophones placed on the surface of a horizontal snow pack. The theory is shown to be consistent with the mechanical properties of alpine snow and known characteristics of slab avalanche release.
Interactive Planning of Infrastructure: The Changing Role of Dutch Project Management
Authors: Glasbergen Pieter , Driessen Peter P J
Published: April 2005

The mode of planing for infrastructure has changed in the Netherlands. As elsewhere, a hierarchic mode of planning has been replaced by regulatory relationships among stakeholders. The authors present a lens through which some of these changes are brought into focus: the new form of cooperation, called ‘interactive planning’, is characterized in terms of ‘political space’, ‘architecture’, and ‘action mechanisms’. The discussion is focused on four projects in which the transition to a new planning mode occurred while the project was being developed. The authors also revisit the implementation of interactive planning.
The History of Astrophysics in Antarctica
Authors: Indermuehle Balthasar T. , Burton Michael G. , Maddison Sarah T.
Published: April 2005

We examine the historical development of astrophysical science in Antarctica from the early 20th century until today. We find three temporally overlapping eras, each having a rather distinct beginning. These are the astrogeological era of meteorite discovery, the high energy era of particle detectors, and the photon astronomy era of microwave, submillimetre, and infrared telescopes, sidelined by a few niche experiments at optical wavelengths. The favourable atmospheric and geophysical conditions are briefly examined, followed by an account of the major experiments and a summary of their results.
A Photometric Study of the Newly Discovered Eclipsing Cataclysmic Variable SDSS J040714.78–064425.1
Authors: Ak T. , Retter A. , Liu A. , Esenoğlu H. H.
Published: April 2005

We present the results obtained from unfiltered photometric CCD observations of the newly discovered cataclysmic variable SDSS J040714.78–064425.1 made during seven nights in 2003 November. We establish the dwarf nova nature of the object as it was in outburst during our observations. We also confirm the presence of deep eclipses with a period of 0.17017 ± 0.00003 d in the optical light curve of the star. In addition, we found periods of 0.166 ± 0.001 d and possibly also 5.3 ± 0.7 d in the data. The 0.17017 d periodicity is consistent within the errors with the proposed orbital period of 0.165 and 0.1700 d. Using the known relation between the orbital and superhump periods, we interpret the 0.166 and 5.3 d periods as the negative superhump and the nodal precession period respectively. SDSS J040714.78–064425.1 is then classified as a negative superhump system with one of the largest orbital periods.
A single intermolecular contact mediates intramolecular stabilization of both RNA and protein
Authors: Calabro Valerie , Daugherty Matthew D. , Frankel Alan D.
Published: April 2005

An arginine-rich peptide from the Jembrana disease virus (JDV) Tat protein is a structural “chameleon” that binds bovine immunodeficiency virus (BIV) or HIV TAR RNAs in two different binding modes, with an affinity for BIV TAR even higher than the cognate BIV peptide. We determined the NMR structure of the JDV Tat–BIV TAR high-affinity complex and found that the C-terminal tyrosine in JDV Tat forms a network of inter- and intramolecular hydrogen bonding and stacking interactions that simultaneously stabilize the β-hairpin conformation of the peptide and a base triple in the RNA. A neighboring histidine also appears to help stabilize the peptide conformation. Induced fit binding is recurrent in protein–protein and protein–nucleic acid interactions, and the JDV Tat complex demonstrates how high affinity can be achieved not only by optimization of the binding interface but also by inducing new intramolecular contacts that stabilize each binding partner. Comparison to the cognate BIV Tat peptide–TAR complex shows how such a costabilization mechanism can evolve with only small changes to the peptide sequence. In addition, the bound structure of BIV TAR in the chameleon peptide complex is strikingly similar to the bound conformation of HIV TAR, suggesting new strategies for the development of HIV TAR binding molecules.
Altruistic punishment and the origin of cooperation
Authors: Fowler James H.
Published: April 2005

How did human cooperation evolve? Recent evidence shows that many people are willing to engage in altruistic punishment, voluntarily paying a cost to punish noncooperators. Although this behavior helps to explain how cooperation can persist, it creates an important puzzle. If altruistic punishment provides benefits to nonpunishers and is costly to punishers, then how could it evolve? Drawing on recent insights from voluntary public goods games, I present a simple evolutionary model in which altruistic punishers can enter and will always come to dominate a population of contributors, defectors, and nonparticipants. The model suggests that the cycle of strategies in voluntary public goods games does not persist in the presence of punishment strategies. It also suggests that punishment can only enforce payoff-improving strategies, contrary to a widely cited “folk theorem” result that suggests that punishment can allow the evolution of any strategy.
Pushing Forces Drive the Comet-like Motility of Microtubule Arrays inDictyostelium
Authors: Brito Daniela A. , Strauss Joshua , Magidson Valentin , Tikhonenko Irina , Khodjakov Alexey , Koonce Michael P.
Published: April 2005

Overexpression of dynein fragments in Dictyostelium induces the movement of the entire interphase microtubule array. Centrosomes in these cells circulate through the cytoplasm at rates between 0.4 and 2.5 μm/s and are trailed by a comet-tail like arrangement of the microtubule array. Previous work suggested that these cells use a dynein-mediated pulling mechanism to generate this dramatic movement and that similar forces are at work to maintain the interphase MTOC position in wild-type cells. In the present study, we address the nature of the forces used to produce microtubule movement. We have used a laser microbeam to sever the connection between the motile centrosomes and trailing microtubules, demonstrating that the major force for such motility results from a pushing on the microtubules. We eliminate the possibility that microtubule assembly/disassembly reactions are significant contributors to this motility and suggest that the cell cortex figures prominently in locating force-producing molecules. Our findings indicate that interphase microtubules in Dictyostelium are subject to both dynein- and kinesin-like forces and that these act in concert to maintain centrosome position in the cell and to support the radial character of the microtubule network.
A Nonribosomal Landscape in the Nucleolus Revealed by the Stem Cell Protein Nucleostemin
Authors: Politz Joan C. Ritland , Polena Ilvin , Trask Ian , Bazett-Jones David P. , Pederson Thoru
Published: April 2005

Nucleostemin is a p53-interactive cell cycle progression factor that shuttles between the nucleolus and nucleoplasm, but it has no known involvement in ribosome synthesis. We found the dynamic properties of nucleostemin differed strikingly from fibrillarin (a protein directly involved in rRNA processing) both in response to rRNA transcription inhibition and in the schedule of reentry into daughter nuclei and the nucleolus during late telophase/early G1. Furthermore, nucleostemin was excluded from the nucleolar domains in which ribosomes are born—the fibrillar centers and dense fibrillar component. Instead it was concentrated in rRNA-deficient sites within the nucleolar granular component. This finding suggests that the nucleolus may be more subcompartmentalized than previously thought. In support of this concept, electron spectroscopic imaging studies of the nitrogen and phosphorus distribution in the nucleolar granular component revealed regions that are very rich in protein and yet devoid of nucleic acid. Together, these results suggest that the ultrastructural texture of the nucleolar granular component represents not only ribosomal particles but also RNA-free zones populated by proteins or protein complexes that likely serve other functions.
The Design of a Storage Server for Continuous Media
Authors: Lougher P. , Shepherd D.
Published: April 2005

The increasing use of multimedia in computing is demanding more powerful computer hardware and system software. In particular, the stringent demands placed on multimedia file servers are unable to be satisfied by current magnetic disk technology or by current file systems techniques. This paper describes the design and implementation of a file server which has been specially optimized for continuous media. The critical performance issues which this paper addresses are the use of disk striping to provide high bandwidth, optimized disk layouts, hard real-time disk scheduling to ensure stream storage and retrieval guarantees are met, and a user interface to support high level multimedia abstractions.