bluuebunny/crossref_metadata_2025 huggingface dataset:
Updated semi‐discretization method for periodic delay‐differential equations with discrete delay
Authors: Insperger Tamás , Stépán Gábor
Published: July 2004

An updated version of the semi‐discretization method is presented for periodic systems with a single discrete time delay. The delayed term is approximated as a weighted sum of two neighbouring discrete delayed state values and the transition matrix over a single period is determined. Stability charts are constructed for the damped and delayed Mathieu equation for different time‐period/time‐delay ratios. The convergence of the method is investigated by examples. Stability charts are constructed for 1 and 2 degree of freedom milling models. The codes of the algorithm are also attached in the appendix. Copyright © 2004 John Wiley & Sons, Ltd.
Melt processing of PA‐66/clay, HDPE/clay and HDPE/PA‐66/clay nanocomposites
Authors: Mehrabzadeh Mahmood , Kamal Musa R.
Published: July 2004

Polyamide 66/clay, high‐density polyethylene (HDPE)/clay and HDPE/PA66/clay nanocomposites were prepared, using a twin‐screw extruder. The nanocomposites were characterized by means of transmission electron microscopy (TEM), scanning electron microscopy (SEM), wide angle X‐ray diffraction (WAXD), differential scanning calorimetry (DSC), optical microscopy and tensile testing. Effects of processing conditions and clay modifier were evaluated. The results show that exfoliation in the twin‐screw extruder is enhanced by the incorporation of mixing and shearing elements and high residence times. Compatibility of the clay modifier with the polymer matrix plays an important role in exfoliation. Clay does not influence the crystal form, melting temperature or crystallinity of PA‐66 and HDPE. However, it acts as a nucleation agent, increases marginally the crystallization temperatures, and reduces the crystallite size. Clay in the blend nanocomposites acts as a compatibilizer and changes the morphology of the blend. TEM micrographs suggest the presence of an exfoliated structure in PA‐66 and an intercalated structure in HDPE. Polym. Eng. Sci. 44:1152–1161, 2004. © 2004 Society of Plastics Engineers.
Epoxy‐phenolic novolac‐montmorillonite hybrid nanocomposites: Novel synthesis methods and their characteristics
Authors: Lee Sang Min , Hwang Tae Ryong , Song Yang Sun , Lee Jae Wook
Published: July 2004

Epoxy resin‐layered silicate nanocomposites (ER‐LSN) were successfully synthesized using pre‐intercalated novolac resin‐layered silicate nanocomposites (NR‐LSN) as epoxy hardeners to develop novel formulations for copper‐clad laminate sheets (CCLS) with enhanced properties. We used melt, melt‐ultrasonic, solution, and solution‐ultrasonic intercalation methods to prepare NR‐LSN with different kinds of novolac resins including phenolic novolac (PN), bisphenol‐A novolac (BN) and phenolic aralkyl novolac, so‐called Xylok (XK). We employed different kinds of montmorillonites (MMT) that were organically modified with benzyl dimethyl octadecyl ammonium and bis(2‐hydroxy‐ethyl)methyl tallow ammonium. It was confirmed that the synthesized NR‐LSN and ER‐LSN were intercalated or exfoliated, and exhibited stable structure owing to the effective action of high‐intensity ultrasound. These materials showed significantly improved thermal and mechanical properties suitable for halogen‐free CCLS with highly reliable performance. Polym. Eng. Sci. 44:1170–1177, 2004. © 2004 Society of Plastics Engineers.
Morphology and performance of epoxy nanocomposites modified with organoclay and rubber
Authors: Liu Weiping , Hoa Suong V. , Pugh Martin
Published: July 2004

Hybrid epoxy nanocomposites modified with carboxyl‐terminated butadiene acrylonitrile (CTBN) rubber and organoclay were synthesized. The morphology of those nanocomposites was studied with X‐ray diffraction (XRD), Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). The results showed that most of the organoclay in the nanocomposites was exfoliated and high cure temperatures benefit the formation of exfoliated nanocomposites. Organoclay simultaneously improved fracture toughness, compressive modulus, yield strength and ultimate strength of the epoxy resin. Organoclay not only enhanced Tg, yield strength and ultimate strength of rubber‐modified epoxies, but also further improved their fracture toughness. There was a superposition effect on fracture toughness of the hybrid epoxy nanocomposites modified with both rubber and organoclay. Polym. Eng. Sci. 44:1178–1186, 2004. © 2004 Society of Plastics Engineers.
Geometry and binding properties of different multiple‐state glycine–Fe+/Fe2+ complexes
Authors: Ai Hongqi , Bu Yuxiang , Li Ping , Li Zhiqiang , Hu Xiangquan , Chen Zhida
Published: July 2004

Several biologically relevant glycine–Fe+/Fe2+ complexes with three different multiplicities were studied for the first time by using the hybrid three‐parameter B3LYP density functional method with different basis sets. Single‐point calculations were also carried out at the BHLYP level with a larger basis set to refine and calibrate these energy values. The results show that the most stable glycine–Fe+ isomer is the C1‐symmetric sextet NO‐16, in which Fe+ is interacted with both the amino nitrogen and carbonyl oxygen of the glycine ligand. The ground‐state structure of glycine–Fe2+ is the 5A′′ state 2O‐25, which generates from the interaction of Fe2+ with the two oxygen terminus of the zwitterionic glycine. The calculations indicate that the binding energies mainly derive from the contributions of electrostatic effects, for both the monovalent and divalent metal cation‐chelated glycine complexes. The differences in binding energies between these different multiple‐state glycine–Fe+ isomers with same combination modes mainly derive from their different electrostatic and polarized effects, and those between the isomers of different combination modes with the same multiple states mainly stem from their different deformation effects. The differences in the relative stabilities of these glycine–Fe+ isomers with different multiple states mainly come from the fact that the more electrostatic contribution of the lower spin complex cannot compensate for the loss of energy enhancement of its corresponding metal cation relative to that of the higher spin counterpart. The same is true for the glycine–Fe2+ complexes. Copyright © 2004 John Wiley & Sons, Ltd.
Acidochromism of C2‐symmetrical aza‐analogues of 1,4‐distyrylbenzene
Authors: Detert Heiner , Sadovski Oleg , Sugiono Erli
Published: July 2004

A series of C2‐symmetrical aza‐analogous 1,4‐distyrylbenzenes were synthesised via two‐fold PO‐activated olefinations or Heck reactions. Pyridine, pyrimidine and quinoline were used as terminal rings, and the 2,5‐positions of the central benzene ring were substituted with H, alkoxy, or alkylsulfonyl groups. These strongly fluorescent compounds are freely soluble in common solvents such as toluene or chloroform. Whereas the electronic spectra of the pyridine and pyrimidine chromophores were very similar to those of the parent compound 1,4‐distyrylbenzene, the spectra of the former were altered considerably in the presence of trifluoroacetic acid. Depending on the concentration of the acid, protonation of the ground state and/or the excited state caused bathochromic shifts of the absorption and the emission spectra, accompanied by reductions in the fluorescence efficiencies. Copyright © 2004 John Wiley & Sons, Ltd.
Chemical messengers: mediated oxidations with the enzyme laccase
Authors: Galli Carlo , Gentili Patrizia
Published: July 2004

The use of low molecular‐weight compounds (viz., mediators) in combination with fungal laccase makes the enzyme suitable for the oxidation of ‘non‐natural’ non‐phenolic substrates. Benzyl alcohols are thus oxidised to carbonylic products by laccase/mediator systems in the presence of oxygen, although laccase cannot oxidise these substrates directly. The reaction is carried out by the oxidised form of the mediator (Medox), generated on its interaction with laccase, and the structure of the Medox species is crucial for the mechanism of the ensuing non‐enzymatic oxidation of the substrate. 1‐Hydroxybenzotriazole (HBT), N‐hydroxyphthalimide (HPI), violuric acid (VLA) and TEMPO have been investigated as mediators, and experimental evidence is provided that enables the radical hydrogen atom transfer route with the laccase/HBT, laccase/HPI and laccase/VLA systems to be assessed unambiguously, although the laccase/TEMPO system follows a different and ionic oxidation route. Copyright © 2004 John Wiley & Sons, Ltd.
Three‐centre hydrogen bonding in the complexes of syn‐2,4‐difluoroadamantane with 4‐fluorophenol and hydrogen fluoride
Authors: Adcock William , Graton Jérôme , Laurence Christian , Luçon Maryvonne , Trout Neil
Published: July 2004

Hydrogen bond enthalpies for the interaction of 4‐fluorophenol with syn‐2,4‐difluoroadamantane (5) and, for comparison, 2‐fluoroadamantane (6) and 1,3‐difluoroadamantane (7) have been determined by Fourier transform infrared spectrometry. Among a series of seven fluoroalkanes (1–7) it is found that syn‐2,4‐difluoroadamantane is the best hydrogen bond acceptor. This high hydrogen bond acceptor strength is explained, using electrostatic and ‘atoms in molecules’ properties and from density functional theory and ab initio calculations on hydrogen fluoride complexes, by the formation of an F·H·F three‐centre hydrogen bond. In this system, the three‐centre hydrogen bonding is energetically (mainly on the Gibbs energy scale) superior to the two‐centre hydrogen bonding. Copyright © 2004 John Wiley & Sons, Ltd.
Quadrupolar donor–acceptor substituted oligo(phenylenevinylene)s—synthesis and solvatochromism of the fluorescence
Authors: Detert Heiner , Schmitt Volker
Published: July 2004

The electronic spectra of oligo(phenylenevinylene)s with five benzene rings and an acceptor–donor–acceptor substitution pattern were investigated. Although the absorption spectra are mostly unaffected by an increasing solvent polarity, both bathochromic shifts and reduced efficiencies of the fluorescence arise with the quadrupolar electronic structure. The chromophores with the lowest oxidation or reduction potentials are the most sensitive towards the environment. The synthesis of the centrosymmetrical oligomers was performed in a sequence of two two‐fold Wittig–Horner olefinations. Copyright © 2004 John Wiley & Sons, Ltd.
Towards Optimal Descriptor Subset Selection with Support Vector Machines in Classification and Regression
Authors: Fröhlich Holger , Wegner Jörg K. , Zell Andreas
Published: July 2004

In this paper we present a novel method for selecting descriptor subsets by means of Support Vector Machines in classification and regression – the Incremental Regularized Risk Minimization (IRRM) algorithm. In contrast to many other wrapper methods it is fully deterministic and computationally efficient. We compare our method to existing algorithms and present results on a Human Intestinal Absorption (HIA) classification data set and the Huuskonen regression data set for aqueous solubility.
Quantitative Structure‐Retention Relationships (QSRR) of Some CNS Agents Studied on DB‐5 and DB‐17 Phases in Gas Chromatography
Authors: Hodjmohammadi M. R. , Ebrahimi P. , Pourmorad F.
Published: July 2004

A QSRR study was performed to develop a predictive model correlating molecular structures with their RIs in gas chromatography. CNS agents included some benzodiazepines, barbiturates and phenytoin, which had been studied, previously, on two DB stationary phases with different phenyl percentages. At first, a high quality model (R=0.988, F=253.89 for DB‐5 and R=0.983, F=164.721 for DB‐17 column) was generated for two columns separately, using only calculated descriptors and multiple linear regression techniques. Then a combined model, added a polarity term of stationary phase (M), was also developed for these columns, and the result was satisfactory (R=0.989, F=232.354). The results of leave‐one‐out cross and external validation techniques showed good predictive ability of the models (R$\rm{ {_{cv}^{2}}}$=0.967, R$\rm{ {_{Prediction\ set}^{2}}}$=0.954). The results of the study indicated that a six‐parameter equation can be utilized for prediction of retention indices of compounds on DB‐5 and DB‐17 stationary phases simultaneously, for which there are no empirical RI values.
Intermolecular interaction energies for deprotonated complexes
Authors: Masamura M.
Published: July 2004

The intermolecular interaction energies of the deprotonated hydrogen‐bonded complexes F−(HF), F−(H2O), F−(NH3), Cl−(HF), SH−(HF), H2P−(HF), OH−(H2O), OH−(H2O)2, OH−(NH3), Cl−(H2O), SH−(H2O), H2P−(H2O), Cl−(NH3), SH−(NH3), H2P−(NH3), Cl−(HCl), Cl−(H2S), Cl−(PH3), SH−(H2S), SH−(PH3), and H2P−(PH3) in complete basis set limit at the MP2, MP4, QCISD(T), and CCSD(T) levels were calculated with correlation consistent basis sets. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Electric field integrals for Slater‐type orbitals
Authors: Fernández Rico J. , López R. , Ramírez G. , Ema I.
Published: July 2004

General algorithms for electric field integrals with Slater‐type orbitals (STO) are reported, and the efficiency of the computational procedure based in these algorithms is analyzed. An accuracy of nine decimal places, at least, is estimated for the molecular electric field computed on any point. Timing was examined for calculations with STO basis sets ranging from 30 to 300 basis functions. Computational cost was moderate, even for the largest basis set. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Chemical bond modeling with correlation effects included
Authors: Abarenkov I. V. , Smelkov K. V.
Published: July 2004

The one‐electron pseudo‐atom potential is developed following the chemical bond modeling method we proposed earlier 1, 2 in the HF approximation. The bond orbital, exact in the HF approximation, is the solution of the closed‐shell HF equation for two electrons in the field of two pseudo‐atoms connected with the bond. The closed shell HF bond energy reproduces the bond adiabatic potential fairly well in the vicinity of the equilibrium bond length. However, for larger distances the results are bad due to the deficiency of one closed shell approximation for the bond at large interatomic separation. The few‐to‐many configuration calculations of the two‐electron problem for the single chemical bond are reported here. The pseudo‐atom potential used in these calculations is calculated in the HF approximation at the equilibrium bond length and fixed. The results for some carbon‐containing molecules are presented and discussed here. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Zentrum Paul Klee – Entwurf und Konstruktion der Museumswelle
Authors: Lang Robert , Schmid Volker
Published: July 2004

Das vom Renzo Piano Building Workshop entworfene “Zentrum Paul Klee” in Bern besticht durch die ungewöhnliche Wellenform des Daches. Der Aufsatz beschreibt den Entwurf und die besondere Geometrie des neuen Museumskomplexes und erläutert die Umsetzung der von gestalterischen Gesichtspunkten geprägten Dachform in ein adäquates Tragwerk. Die strukturellen Besonderheiten und die Detaillierung des aus geschweißten Stahlträgern errichteten Dachtragwerks werden dargestellt.
Wandelbares Membrandach im Innenhof des Wiener Rathauses
Authors: Bergermann Rudolf , Gugeler Jochen , Keck Thomas
Published: July 2004

Im September 2000 wurde das wandelbare Membrandach über dem Arkadenhof des Wiener Rathauses eingeweiht. Als Regen‐ und Sonnenschutz für die zahlreichen Veranstaltungen ersetzt die neue 34 m ∞ 32 m große Konstruktion die bisher verwendeten Zelte. An den Längsseiten des Daches sind Schienen angeordnet, auf denen die Laufwagen der in Querrichtung gespannten Tragseile verfahren werden. Die Membran trägt zwischen diesen sogenannten Gratseilen praktisch einachsig in Dachlängsrichtung. Die Dachkehle – zwischen jeweils zwei Gratseilen – wurde so ballastiert, daß sich die Membran beim Verfahren wie eine Ziehharmonika zwischen Grat und Kehle auffaltet.
Hochgebirgsattraktionen aus Stahl
Authors: Huber Gerald , Aste Christian
Published: July 2004

Die neuen Stahl‐Attraktionen im Skigebiet Sölden (Österreich) auf über 3000 m Seehöhe bringen die faszinierende Bergwelt spürbar nahe. Die extremen Belastungs‐ und Montagebedingungen im alpinen Hochgebirge sowie die sichtbar bleibenden konstruktiven Details machten diese touristisch viel beachteten Gipfelsymbole auch ingenieurtechnisch zu einer besonderen Herausforderung.
Berechnungsverfahren zur Ermittlung der Wärmedurchgangskoeffizienten von zweischaligen Wand‐ und Dachaufbauten in Leichtbauweise
Authors: Loose Tobias , Saal Helmut
Published: July 2004

Die Energieeinsparverordnung fordert bei der Berechnung der Transmissionswärmeverluste die Berücksichtigung von Wärmebrücken. Berechnungsverfahren, die diese Wärmebrückenverluste bei der Ermittlung des Wärmedurchgangskoeffizienten berücksichtigen, werden für sechs Wand‐ und zwei Dachaufbauten vorgestellt. Diese Berechnungsverfahren, die sich an die Schwedische Norm SS 02 42 30 halten, sind sehr rechenaufwendig und werden deshalb mit Hilfe von Nomogrammen vereinfacht.
Zur sicheren Anwendung feuerverzinkter Stahlträger
Authors: Sedlacek Gerhard , Dahl Winfried , Hoffmeister Benno , Kühn Bertram , Feldmann Markus , Pinger Thomas , Langenberg Peter , Eichenmüller Helena , Grotmann Dietmar , Blum Marc
Published: July 2004

Bei feuerverzinkten Stahlträgern u.a. für den Parkhausbau sind in der Vergangenheit Risse aufgetreten, hauptsächlich Längsrisse im Steg der Träger, die von geschweißten Teil kopfplatten ausgingen, vereinzelt auch Risse am Untergurt quer zum Träger, die an lokalen Druckstellen infolge Kaltverformung zum Vorkrümmen der Träger ihren Anfang nahmen.

Der Aufsatz geht den wechselseitigen Ursachen der Rißbildung bei der Verzinkung entsprechend dem derzeitigen Stand der Forschung nach und gibt vorläufige Empfehlungen zur Werkstoffwahl, konstruktiven Ausbildung sowie Fertigung und Feuerverzinkung, um in Zukunft Risse zu vermeiden.
Subareolar Subcutaneous Injection of Blue Dye versus Peritumoral Injection of Technetium‐labeled Human Albumin to Identify Sentinel Lymph Nodes in Breast Cancer Patients
Authors: Reitsamer Roland , Peintinger Florentia , Rettenbacher Lukas , Prokop Eva , Sedlmayer Felix
Published: July 2004

Lymphatic mapping in breast cancer patients is a widely used technique for axillary staging, though the optimal technique is not yet established. The purpose of this study was to show that subareolar and subcutaneous injection of blue dye drains to the same sentinel lymph node (SLN) in the axillary basin as does peritumoral injection of technetium (Tc)‐labeled albumin. Two injection methods were compared in 154 consecutive patients with newly diagnosed pT1 or pT2 breast cancers (tumor size 5–45 mm). The diagnosis of invasive breast cancer was confirmed by core needle biopsy. Peritumoral injection of 40 to 60 MBq 99Tc‐labeled colloidal albumin was performed 18 to 20 hours prior to surgery. In addition, 2 ml of blue dye was injected subcutaneously into the subareolar plexus of the same patients exactly 5 minutes prior to incision and dissection of the SLNs. The blue and hot SLNs were identified by searching for the blue lymphatic vessel and the blue lymph node and by counting the radioactivity with a gamma probe. The correlation between the blue nodes and the hot nodes was examined. Altogether, 154 patients were enrolled in the study. Three patients had bilateral breast cancer, and a total of 157 sentinel lymph node biopsies (SLNBs) were performed. The SLNs could be identified in 155 of the 157 SLNBs (98.7%), and the hot node clearly corresponded to the blue node in 151 of the 155 SLNBs (97.4%). Neither a hot node nor a blue node could be identified in 2 of the 157 SLNBs (1.3%). No concordance between the blue node and the hot node could be achieved in 4 of the 155 SLNBs (2.6%). Injection of blue dye into the subareolar lymphatic plexus shows excellent correlation with peritumoral injection of technetium‐labeled albumin concerning the identification of SLNs. Our results support the hypothesis that the lymphatic drainage of the breast parenchyma and the subareolar plexus leads to the same sentinel lymph node. It is a rapid, reliable method for identifying SLNs in breast cancer patients. It is easy to perform, especially in nonpalpable tumors, and it does not disturb surgery by discoloring peritumoral tissue.
Malassezia furfur Meningitis Associated with Total Parenteral Nutrition Subdural Effusion
Authors: Rosales Cecilia M. , Jackson Mary Anne , Zwick David
Published: July 2004

We present a case of Malassezia furfur meningitis arising in a very low birth weight infant with chronic lung disease, necrotizing enterocolitis, and intraventricular hemorrhage. M. furfur meningitis was probably acquired late following successful treatment for earlier systemic central line-associated M. furfur infection. M. furfur meningitis has only once been previously reported. Unlike the previous case where meningitis was secondary to widespread blood-borne dissemination, infection was limited to the leptomeninges and arose in association with extravasation of total parenteral nutrition (TPN) and intralipid fluid into subarachnoid space via peripheral scalp catheter.
Fatal Congenital Systemic Juvenile Xanthogranuloma with Liver Failure
Authors: Hu Weimin K. , Gilliam Anita C. , Wiersma Susan R. , Dahms Beverly B.
Published: July 2004

This is the second reported patient with systemic juvenile xanthogranuloma (JXG) to die with liver failure. The infant was born with multiple skin lesions and mild hepatomegaly. Direct hyperbilirubinemia was noted on the 2nd day of life, followed by progressive hepatomegaly, cholestasis, and death at 29 days of age. At autopsy, nodular tumor infiltrates of JXG were present throughout the liver, as well as in skin, abdominal lymph nodes, spleen, and pancreas.
Compressive shear faults within arctic sea ice: Fracture on scales large and small
Authors: Schulson Erland M.
Published: July 2004

We examined fracture features within arctic sea ice as revealed by Landsat‐7 and RADARSAT imagery, by an aerial survey, and through observations in the laboratory of specimens loaded to brittle failure under biaxial compression. Regardless of scale, which spans the range from kilometers to millimeters, the features look alike. They consist mainly of narrow lineaments that traverse the field of view, plus wing‐like and comb‐like secondary cracks. The lineaments occasionally intersect and generally exhibit either right‐lateral or left‐lateral relative movement, like strike‐slip faults within Earth's crust. We term them brittle compressive shear faults. They form through the linking of en echelon arrays of deformation‐induced secondary cracks. From an application of wing‐crack and comb‐crack mechanics, we estimated the maximum compressive stress near the onset of faulting and found that our estimates compare favorably with in situ measurements by earlier investigators of ice sheet failure stresses. To account for the brittle behavior of the sea ice cover, we applied a recent model of the ductile‐to‐brittle transition in which the key idea is the competition between stress buildup and stress relaxation at stress concentrators. In identifying the nature of sea ice fracture features, we advance the view that failure occurs on many scales through highly localized as opposed to uniformly distributed deformation, via the operation of scale‐independent mechanisms.
Folding and inversion tectonics in the Anti‐Atlas of Morocco
Authors: Helg Urs , Burkhard Martin , Caritg Séverine , Robert‐Charrue Charles
Published: July 2004

The late Variscan Anti‐Atlas of Morocco shows some conspicuous deviations from the standard anatomy of foreland fold‐and‐thrust belts. Large basement inliers crop out at a very short distance of less than 50 km behind the southeastern front of the fold belt, reminiscent of Windriver‐style basement uplifts. In contrast to the Rocky Mountain foreland, however, the Anti‐Atlas basement uplifts punctuate tightly folded Paleozoic cover series similar in tectonic style to the Appalachian Valley and Ridge province. Cover shortening is exclusively accommodated by buckle folding, and the Anti‐Atlas fold belt lacks any evidence for duplexing or thrust faults other than the occasional steep reverse fault found near basement inliers. Basement domes have classically been considered as the result of vertical tectonics in a horst and graben fashion, or, alternatively, as large “plis de fond” [Argand, 1924], basement folds. Unfolding of a large portion of an Ordovician quartzite marker bed reveals a minimum shortening of 17% (30 km). Balancing this section at the crustal scale indicates a lower crustal detachment level at 18 to 25 km depth. Basement shortening is inferred to be accommodated through massive inversion of former extensional faults, inherited from a Late Proterozoic‐Lower Cambrian rifting phase.
Catchment‐scale mapping of surface grain size in gravel bed rivers using airborne digital imagery
Authors: Carbonneau Patrice E. , Lane Stuart N. , Bergeron Normand E.
Published: July 2004

This study develops and assesses two methods for estimating median surface grain sizes using digital image processing from centimeter‐resolution airborne imagery. Digital images with ground resolutions of 3 cm and 10 cm were combined with field calibration measurements to establish predictive relationships for grain size as a function of both local image texture and local image semivariance. Independently acquired grain size data were then used to assess the algorithm performance. Results showed that for the 3 cm imagery both local image semivariance and texture are highly sensitive to median grain size, with semivariance being a better predictor than image texture. However, in the case of 10 cm imagery, sensitivity of image semivariance and texture to grain size was poor, and this scale of imagery was found to be unsuitable for grain size estimation. This study therefore demonstrates that local image properties in very high resolution digital imagery allow for automated grain size measurement using image processing and remote sensing methods.
Central role for liver X receptor in insulin-mediated activation of
Srebp-1c
transcription and stimulation of fatty acid synthesis in liver
Authors: Chen Guoxun , Liang Guosheng , Ou Jiafu , Goldstein Joseph L. , Brown Michael S.
Published: July 2004

Transcription of the gene encoding sterol regulatory element-binding protein 1c (SREBP-1c) is known to be activated by insulin in the liver. The resultant SREBP-1c protein activates transcription of the genes required for fatty acid synthesis. Here, we use SREBP-1c promoter reporter constructs to dissect the mechanism of insulin activation in freshly isolated rat hepatocytes. The data show that a complete insulin response (increase of 6- to 11-fold) requires two binding sites for liver X receptors (LXRs), which are nuclear receptors that are activated by oxygenated sterols. Disruption of these binding sites did not lower basal transcription but severely reduced the response to insulin. In contrast, disruption of the closely linked binding sites for SREBPs and nuclear factor Y lowered basal transcription drastically but still permitted a 4- to 7-fold increase in response to insulin. Arachidonic acid, an inhibitor of LXR activation, blocked the response to insulin. We conclude that insulin activates the SREBP-1c promoter primarily by increasing the activity of LXRs, possibly through production of a ligand that activates LXRs or their heterodimerizing partner, the retinoid X receptor. Nuclear SREBPs and nuclear factor Y play permissive roles.
Corporatism and the Theory of the Firm: Lessons from the Portuguese Experience
Authors: Bastien Carlos , Luís Cardoso José
Published: July 2004

In 1933, Portugal was officially converted to a corporatist state, a state where it was accepted that the semi-autonomous bodies representing the various branches of economic and social activity would have formal powers in defining public policies. In such a context, an important change also occurred at the level of economic theories and doctrines, in keeping with the novelties emanating from both the legal and political fields.
“Old” Economic History in the United States: 1939–1954
Authors: de Rouvray Cristel
Published: July 2004

This paper investigates the actions of a small, yet influential group of American economists who sought to claim economic history for themselves and use it as a springboard to launch a wider transformation of economics. Their actions constitute an episode of dissent in the history of twentieth century economics, albeit an unusual one. These dissenters were not a socially or intellectually marginalized group, but rather a set of privileged scholars who were able to leverage their contacts within the profession and amongst its patrons to further their vision. Their actions could almost be described in Kuhnian terms: they consciously sought to trigger a “paradigm shift” to bring about a social science better suited, in their views, to a world in political and economic turmoil (Kuhn 1962). In spite of the Kuhnian allusion to “scientific revolution,” this paper is not about the 1960s “cliometric revolution,” but about the 1940s and '50s and the little known events that led to the creation of the Economic History Association, the Journal of Economic History, and Explorations in Entrepreneurial History (subsequently Explorations in Economic History).
Constructing Identity: The Post Keynesians and the Capital Controversies
Authors: Mata Tiago
Published: July 2004

Economics in the 1960s was host to a number of dissenting movements challenging the profession's mainstream theories. As this mainstream changed in the 1970s, the dissenters also underwent a transformation of their own. By the late 1970s the dispersed dissenting voices had congregated to form groups of neo-Austrians, post-Keynesians, neo-Marxists and radical economists. Retrospectively, the 1970s appear as a period of intense negotiation among dissenters as they erected theoretical and methodological boundaries and institutions (associations, journals, seminars) that would come to define them. They were constructing not just conditions for carrying on their work but also a narrative perception of who they were, what they stood for and what was the nature of the profession they inhabited, which I hereafter call “identity” or “self-image.” The dispersed critiques were being redrawn into new sociological unities inside the profession. This paper aims to track one of the routes that brought dispersed critique into an organized and self-conscious grouping, self-identified as Post Keynesian economics. The broad question addressed is how did the Post Keynesians construct their identity?
Master Curve of Separation Processes
Authors: Barsky E. , Barsky M.
Published: July 2004

Processes of gravity classification involve complex two‐phase flows with a multiple‐fraction solid phase. Analytic solutions are still lacking for mass processes that comprise solid particles moving in different directions. Consequently, research on gravity classification has been restricted to the study of empirical regularities. This article presents the latest results in this area. Basic to these results is a new physical phenomenon that has been found to apply to the entire class of gravity separation processes – equivalency of the recoveries of the different particulate fractions. In the turbulent zone this regularity is invariant under the main technological factors of the process: flow velocity of the medium, size and density of the particles, density of the medium, concentration of the solid phase. A method has been found for transforming the main process parameters in the laminar and transitional zones to yield identical correlations. This points to the existence of an underlying law governing the process.
Dynamic Tracking of Acute Ischemic Tissue Fates Using Improved Unsupervised ISODATA Analysis of High-Resolution Quantitative Perfusion and Diffusion Data
Authors: Shen Qiang , Ren Hongxia , Fisher Marc , Bouley James , Duong Timothy Q.
Published: July 2004

High-resolution (200 × 200 × 1,500 μm3) imaging was performed to derive quantitative cerebral blood flow (CBF) and apparent diffusion coefficient (ADC) maps in stroke rats (permanent occlusion) every 30 minutes up to 3 hours after occlusion onset, followed by histology at 24 hours. An improved automated iterative-self-organizing-data-analysis-algorithm (ISODATA) was developed to dynamically track ischemic tissue fate on a pixel-by-pixel basis during the acute phase. ISODATA-resolved clusters were overlaid on the CBF-ADC scatterplots and image spaces. Tissue volume ADC, and CBF of each ISODATA cluster were derived. In contrast to the single-cluster normal left hemisphere (ADC = 0.74±0.02 × 10−3 mm2/s, CBF = 1.36±0.22 mL g−1 min−1, mean±SD, n = 8), the right ischemic hemisphere exhibited three ISODATA clusters, namely: “normal” (normal ADC and CBF), “ischemic core” (low CBF and ADC), and at-risk “perfusion-diffusion mismatch” (low CBF but normal ADC). At 180 minutes, the mismatch disappeared in five rats (Group I, 180-minute “core” lesion volume = 255±62 mm3 and 24-hour infarct volume = 253±55 mm3, P > 0.05), while a substantial mismatch persisted in three rats (Group II, 180-minute CBF-abnormal volume = 198±7 mm3 and 24-hour infarct volume 148±18 mm3, P < 0.05). The CBF (0.3±0.09 mL g−1 min−1) of the “persistent mismatch” (Group II, 0.3±0.09 mL g−1 min−1) was above the CBF viability threshold (0.2 to 0.3 mL g−1 min−1) throughout and its ADC (0.70±0.03 × 10−3 mm2/s) did not decrease as ischemia progressed. In contrast, the CBF (0.08±0.03 mL g−1 min−1) of the analogous brain region in Group I was below the CBF viability threshold, and its ADC gradually decreased from 0.63±0.05 to 0.43±0.03 × 10−3 mm2/s (ADC viability threshold = 0.53±0.02 × 10−3 mm2/s). The modified ISODATA analysis of the ADC and CBF tissue characteristics during the acute phase could provide a useful and unbiased means to characterize and predict tissue fates in ischemic brain injury and to monitor therapeutic intervention.
Human T-cell leukaemia virus type I is highly sensitive to UV-C light
Authors: Shimizu Akira , Shimizu Nobuaki , Tanaka Atsushi , Jinno-Oue Atsushi , Roy Bibhuti Bhusan , Shinagawa Masahiko , Ishikawa Osamu , Hoshino Hiroo
Published: July 2004

The biological characteristics of human T-cell leukaemia virus type I (HTLV-I) are not yet well understood. UV light C (UV-C) sensitivity of HTLV-I was studied using a newly established infectivity assay: infection with cell-free HTLV-I dose-dependently induced syncytial plaques in cat cells transduced with the tax1 gene of HTLV-I. HTLV-I was inactivated by a much lower UV dose than bovine leukaemia virus (BLV). The D10 (10 % survival dose) of HTLV-I was about 20 J m−2, while that of BLV was about 180 J m−2, which was similar to the reported D10 of BLV. The UV sensitivity of HTLV-I and BLV was also examined by detecting viral DNA synthesis 24 h after infection. The D10 values determined by PCR using the gag primers for HTLV-I and BLV were close to those determined by the infectivity assays. Further PCR analyses were then performed to determine D10 values using several different primers located between the 5′-long terminal repeat (5′-LTR) and the tax1 gene. The difference in UV sensitivity between HTLV-I and BLV was detected very early during replication, even during reverse transcription of the 5′-LTR of irradiated viruses, and became more prominent as reverse transcription proceeded towards the tax1 gene. Chimeric mouse retroviruses that contain the LTR-tax1 fragments of HTLV-I and BLV were made and hardly any difference in UV sensitivity was detected between them, suggesting that the difference was not determined by the linear RNA sequences of HTLV-I and BLV. HTLV-I was found to be much more sensitive than other retroviruses to UV.
Influenza A viruses in feral Canadian ducks: extensive reassortment in nature
Authors: Hatchette Todd F. , Walker David , Johnson Christie , Baker Ashley , Pryor S. Paul , Webster Robert G.
Published: July 2004

The current dogma of influenza accepts that feral aquatic birds are the reservoir for influenza A viruses. Although the genomic information of human influenza A viruses is increasing, little of this type of data is available for viruses circulating in feral waterfowl. This study presents the genetic characterization of 35 viruses isolated from wild Canadian ducks from 1983 to 2000, as the first attempt at a comprehensive genotypic analysis of influenza viruses isolated from feral ducks. This study demonstrates that influenza virus genes circulating in Canadian ducks have achieved evolutionary stasis. The majority of these duck virus genes are clustered in distinct North American clades; however, some H6 and H9 genes are clustered with those from Eurasian viruses. Genes appeared to reassort in a random fashion. None of the genotypes identified remained present throughout all of the years examined and most PA and PB2 genes that crossed over into swine were clustered in one phylogenetic grouping. Additionally, matrix genes were identified that branch very early in the evolutionary tree. These findings demonstrate the diversity of the influenza virus gene pool in Canadian ducks, and suggest that genes which cluster in specific phylogenetic groupings in the PB2 and PA genes can be used for markers of viruses with the potential for crossing the species barrier. A more comprehensive study of this important reservoir is needed to provide further insight into the genomic composition of viruses that crossover the species barrier, which would be a useful component to pandemic planning.
Characterization of two distinct prion strains derived from bovine spongiform encephalopathy transmissions to inbred mice
Authors: Lloyd Sarah E. , Linehan Jacqueline M. , Desbruslais Melanie , Joiner Susan , Buckell Jennifer , Brandner Sebastian , Wadsworth Jonathan D. F. , Collinge John
Published: July 2004

Distinct prion strains can be distinguished by differences in incubation period, neuropathology and biochemical properties of disease-associated prion protein (PrPSc) in inoculated mice. Reliable comparisons of mouse prion strain properties can only be achieved after passage in genetically identical mice, as host prion protein sequence and genetic background are known to modulate prion disease phenotypes. While multiple prion strains have been identified in sheep scrapie and Creutzfeldt–Jakob disease, bovine spongiform encephalopathy (BSE) is thought to be caused by a single prion strain. Primary passage of BSE prions to different lines of inbred mice resulted in the propagation of two distinct PrPSc types, suggesting that two prion strains may have been isolated. To investigate this further, these isolates were subpassaged in a single line of inbred mice (SJL) and it was confirmed that two distinct prion strains had been identified. MRC1 was characterized by a short incubation time (110±3 days), a mono-glycosylated-dominant PrPSc type and a generalized diffuse pattern of PrP-immunoreactive deposits, while MRC2 displayed a much longer incubation time (155±1 days), a di-glycosylated-dominant PrPSc type and a distinct pattern of PrP-immunoreactive deposits and neuronal loss. These data indicate a crucial involvement of the host genome in modulating prion strain selection and propagation in mice. It is possible that multiple disease phenotypes may also be possible in BSE prion infection in humans and other animals.
Termination and read-through proteins encoded by genome segment 9 of Colorado tick fever virus
Authors: Jaafar Fauziah Mohd , Attoui Houssam , de Micco Philippe , de Lamballerie Xavier
Published: July 2004

Genome segment 9 (Seg-9) of Colorado tick fever virus (CTFV) is 1884 bp long and contains a large open reading frame (ORF; 1845 nt in length overall), although a single in-frame stop codon (at nt 1052–1054) reduces the ORF coding capacity by approximately 40 %. However, analyses of highly conserved RNA sequences in the vicinity of the stop codon indicate that it belongs to a class of ‘leaky terminators’. The third nucleotide positions in codons situated both before and after the stop codon, shows the highest variability, suggesting that both regions are translated during virus replication. This also suggests that the stop signal is functionally leaky, allowing read-through translation to occur. Indeed, both the truncated ‘termination’ protein and the full-length ‘read-through’ protein (VP9 and VP9′, respectively) were detected in CTFV-infected cells, in cells transfected with a plasmid expressing only Seg-9 protein products, and in the in vitro translation products from undenatured Seg-9 ssRNA. The ratios of full-length and truncated proteins generated suggest that read-through may be down-regulated by other viral proteins. Western blot analysis of infected cells and purified CTFV showed that VP9 is a structural component of the virion, while VP9′ is a non-structural protein.
Host RNA polymerase II makes minimal contributions to retroviral frame-shift mutations
Authors: Zhang Jiayou
Published: July 2004

The rate of mutation during retrovirus replication is high. Mutations can occur during transcription of the viral genomic RNA from the integrated provirus or during reverse transcription from viral RNA to form viral DNA or during replication of the proviral DNA as the host cell is dividing. Therefore, three polymerases may all contribute to retroviral evolution: host RNA polymerase II, viral reverse transcriptases and host DNA polymerases, respectively. Since the rate of mutation for host DNA polymerase is very low, mutations are more likely to be caused by the host RNA polymerase II and/or the viral reverse transcriptase. A system was established to detect the frequency of frame-shift mutations caused by cellular RNA polymerase II, as well as the rate of retroviral mutation during a single cycle of replication in vivo. In this study, it was determined that RNA polymerase II contributes less than 3 % to frame-shift mutations that occur during retrovirus replication. Therefore, the majority of frame-shift mutations detected within the viral genome are the result of errors during reverse transcription.
The P gene of Newcastle disease virus does not encode an accessory X protein
Authors: Peeters Ben , Verbruggen Paul , Nelissen Frank , de Leeuw Olav
Published: July 2004

Many paramyxoviruses encode non-essential accessory proteins that are involved in the regulation of virus replication and inhibition of cellular antiviral responses. It has been suggested that the P gene mRNA of Newcastle disease virus (NDV) encodes an accessory protein – the so-called X protein – by translation initiation at a conserved in-frame AUG codon at position 120. Using a monoclonal antibody that specifically detected the P and X proteins, it was shown that an accessory X protein was not expressed in NDV-infected cells. Recombinant NDV strains in which the AUG was changed into a GCC (Ala) or GUC (Val) codon were viable but showed a reduction in virulence, probably because the amino acid change affected the function of the P and/or V protein.
Birefringence of lead titanate (PbTiO3)
Authors: Zekria D. , Glazer A. M. , Shuvaeva V. , Dec J. , Miga S.
Published: July 2004

Since lead titanate was first grown in single-crystal form in the 1930s, several independent reports of its linear birefringence have been published. Whilst there is overall qualitative agreement on its behaviour with temperature, the absolute values show some degree of variation. At 298 K they range from −0.009 to −0.013, a relative spread of 40%, whilst at 673 K the discrepancy is even greater. This paper reports unexpected results obtained from independent measurements of a selection of crystals that have been grown recently, in which the birefringence is some four times greater than hitherto believed. This has important consequences for the use of birefringence measurement as a means of studying phase transitions in crystals. Intrinsic values of birefringence for lead titanate are measured for the first time.
Particle size distributions from small-angle scattering using global scattering functions
Authors: Beaucage G. , Kammler H. K. , Pratsinis S. E.
Published: July 2004

Control and quantification of particle size distribution is of importance in the application of nanoscale particles. For this reason, polydispersity in particle size has been the focus of many simulations of particle growth, especially for nanoparticles synthesized from aerosols such as fumed silica, titania and alumina. Single-source aerosols typically result in close to a log-normal distribution in size and micrograph evidence generally supports close to spherical particles, making such particles ideal candidates for considerations of polydispersity. Small-angle X-ray scattering (SAXS) is often used to measure particle size in terms of the radius of gyration,Rg, using Guinier's law, as well as particle surface area,S/V, from the Porod constantBand the scattering invariantQ. In this paper, the unified function is used to obtain these parameters and various moments of the particle size distribution are calculated. The particle size obtained from BET analysis of gas adsorption data directly agrees with the moment calculated fromS/V. Scattering results are also compared with TEM particle-counting results. The potential of scattering to distinguish between polydisperse single particles and polydisperse particles in aggregates is presented. A generalized index of polydispersity for symmetric particles, PDI =BRg4/(1.62G), whereGis the Guinier prefactor, is introduced and compared with other approaches to describe particle size distributions in SAXS, specifically the maximum-entropy method.
Structural studies of light-induced excited states
Authors: Thompson Amber L. , Beeby Andrew , Goeta Andrés E.
Published: July 2004

Over the past few years there has been a marked increase in the number of structural studies carried out on light-induced excited states. Until now, however, there has been no systematic approach to the irradiation of samples, which can make data collection difficult and results unreliable. This paper presents a device for mounting a laser on a CCD diffractometer; this device not only enables the collection of data without any constraints on the data collection strategy, but also simplifies alignment of the laser and can be left in place permanently.
PolySNAP: a computer program for analysing high-throughput powder diffraction data
Authors: Barr Gordon , Dong Wei , Gilmore Christopher J.
Published: July 2004

In high-throughput crystallography experiments, it is possible to measure over 1000 powder diffraction patterns on a series of related compounds, often polymorphs or salts, in less than one week. The analysis of these patterns poses a difficult statistical problem. A computer program is presented that can analyse such data, automatically sort the patterns into related clusters or classes, characterize each cluster and identify any unusual samples containing, for example, unknown or unexpected polymorphs. Mixtures may be analysed quantitatively if a database of pure phases is available. A key component of the method is a set of visualization tools based on dendrograms and pie charts, as well as principal-component analysis and metric multidimensional scaling as a source of three-dimensional score plots. The procedures have been incorporated into the computer programPolySNAP, which is available commercially from Bruker-AXS.
Nanocrystalline domain size distributions from powder diffraction data
Authors: Leoni Matteo , Scardi Paolo
Published: July 2004

The need for ana prioridomain size distribution is one of the main limitations of existing line profile analysis methodologies. A numerical modification of the whole-powder-pattern modelling algorithm is proposed, to allow the refinement of a general domain size distribution from powder diffraction data. The shape of domains has to be inferred for the specimen under study. The algorithm is robust enough to unveil fine details in the refined distribution, as witnessed by the results of tests performed both on simulated and on real patterns of nanocrystalline ceria.