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AbstractReading is essential for learning, from literature to physics, from paper to screens on e-readers and smart phones. Even if it is well known that learning to read implies good language skills, children also need to develop good oculomotor and visual-perception skills. Thereby, any deficits in visual processing may affect learning. The possible impact of visual deficits is rarely considered, especially with regard to eye movements and visual perception. Hence, these deficits are usually discovered much later or remain undiagnosed. The present study aimed at assessing the usefulness of visual processing related measures in the early detection of reading difficulties. Visual skill differences that are apparent early in kindergarten might provide predictive insights into risk for learning difficulties at school entry. We used a prospective, longitudinal approach where visual processes (assessed with the Developmental Eye Movement (DEM) test) were measured in 51 preschoolers, and the impact of these processes on future reading development was explored one year later, in Grade 1. Results showed that (1) 31% of our sample of preschoolers showed visual processing impairments (without any clinical complaints) and (2) reading accuracy and speed in first graders were significantly correlated with visual skills assessed in kindergarten, thus confirming the significant role of oculomotor and visual-perception processes in the acquisition of reading skills. These suggests the potential for these measures to be used clinically for identifying children at risk for low academic achievement, enabling appropriate targeting of early interventions.

L’objectif de cette revue de littérature est de s’intéresser aux capacités oculomotrices et visuo-attentionnelles, particulièrement impliquées dans l’activité de lecture. Cet article permet notamment de souligner leur rôle déterminant dans l’apprentissage de la lecture, ainsi que dans la compréhension des difficultés observées chez certains enfants dyslexiques. La prise en considération de ces capacités ainsi que le développement de techniques de dépistage et remédiation adaptées, pourrait permettre à un plus grand nombre d’enfants scolarisés d’améliorer leurs compétences en lecture.

Optical near-field interactions exhibit a hierarchical response, which is one of the most unique attributes of light-matter interactions occurring locally on the nanometer scale. It allows hierarchical nano-optical systems that break through the integration restrictions posed by the diffraction limit of conventional propagating light and offers multiple hierarchical functionalities at different physical scales in the subwavelength regime. Here we demonstrate an information theoretical approach to such nano-optical systems while assessing their electromagnetic and logical aspects via angular-spectrum analysis. Mutual information at each level of the hierarchy reveals quantitatively the relation between the physical effects associated with the hierarchy in the optical near-fields, as well as possible environmental disturbances affecting the system locally or globally, and the system's capabilities for information processing and communication.

Bifunctional ligands able to form neutral complexes with radioactive technetium and rhenium and to couple to biological relevant anchor groups play an important role in the design of new radiopharmaceuticals for diagnosis and therapy. A novel tetradentate amide thioether dithiolate ligand HS-CH2CH2-S-CH2CONH-CH(COOR)CH2SH (H3SNSS) with R=CH3, C10H21was synthesized that forms stable complexes with technetium and rhenium in oxidation state V. The molecular structures of the rhenium and technetium complexes MO(SNSS) were determined by X-ray structural analysis and show that the metal coordination number is five and the coordination polyhedron is between square-pyramidal and trigonal-bipyramidal. The pendent ester group allows coupling of the chelate unit at biologically relevant anchor groups. As a relevant representative the X-ray structural analysis of the rhenium decylester complex was carried out. The complex formation with Tc at the n.c.a. level and 186Re at 10-6M level is described.

In this paper we examine the effects of Internet traffic on the Quality of Service (QoS) in GPRS wireless networks. With a stochastic source traffic model describing the user behavior, we will derive subjective and objective Quality of Service measures in terms of WWW downloading time and the transmission bandwidths on TCP and TBF level. Comparing the obtained values with wireline network modems and ISDN yields a slowdown factor which indicates the subjective degradation that the wireless user experiences.

A novel type of mixed-ligand Tc(III) complexes, [Tc(SCH2CH2−E−CH2CH2S)(PR2S)] (E = S, N(CH3); PR2S = phosphinothiolate with R = aryl, alkyl) is described. These “3+2”-coordinated complexes can be prepared in a two-step reduction/substitution procedure via the appropriate chloro-containing oxotechnetium(V) complex [TcO(SES)Cl] {E = S, N(CH3)}. Tc(III) compounds have been fully characterized both in solid and solution states and found to adopt the trigonal-bipyramidal coordination geometry. The equatorial trigonal plane is formed by three thiolate sulfur atoms, whereas the phosphorus of the bidentate P,S ligand and the neutral donor of the tridentate chelator occupy the apical positions. The ⁹⁹Tc(III) complexes have been proven to be identical with the ^99mTc agents prepared at the no-carrier-added level by comparison of the corresponding UV/vis and radiometric HPLC profiles. Challenge experiments with glutathione clearly indicate that this tripeptide has no effect on the stability of the ^99mTc complexes in solutions. Biodistribution studies have been carried out in rats at 5 and 120 min postinjection. The substituents at the bidentate P,S ligand significantly influence the biodistribution pattern. Remarkable differences are observed especially in brain, blood, lungs, and liver. All the complexes are able to penetrate the blood−brain barrier of rats and showed a relatively fast washout from the brain.

In vielen Fällen sind bei Baugrubenverbaukonstruktionen in weichen Böden dränierte Verhältnisse maßgebend. Beim Nachweis von kurzzeitigen Bauzuständen dagegen sind in der Regel undränierte Bedingungen mit der Scherfestigkeit cu vorauszusetzen. Im Beitrag wird diskutiert, wie sich der Einfluß der Schergeschwindigkeit und der Anisotropie auf die cu‐Werte aus Flügelsondierungen auswirkt. Ferner wird gezeigt, daß die Bestimmung der Einbindetiefe mit dem cu‐Konzept zu Interpretationsschwierigkeiten der Lösung führt. Deshalb empfiehlt der Arbeitskreis Baugruben, mit Ersatzreibungswinkeln zu dimensionieren.

In an attempt to develop new technetium-based radiopharmaceuticals for the noninvasive diagnosis of myocardial metabolism, we have synthesized three examples of novel metal-containing fatty acid derivatives according to the “3+1” mixed-ligand and the Schiff base/tricarbonyl design. The chelates contain the metal core in the oxidation states +5 and +1, respectively, and are attached to the end-position of a fatty acid chain. The complex formation was accomplished by ligand-exchange reactions with three different rhenium precursors, whereas the inactive rhenium metal was utilized as a surrogate of the technetium radionuclide. The molecular structures of the fatty acid complexes 7, 10 and 14 were determined by single-crystal X-ray diffraction analyses and impressively show a general problem in technetium tracer research, namely the significant structural alterations of bioactive molecules by coordination even to small metal chelates. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Starting from the tripodal ligand 2,2‘,2‘ ‘-nitrilotris(ethanethiol) (NS3) and isocyanides (CNR) as co-ligands, neutral mixed-ligand technetium(III) complexes of the general formulation [Tc(NS3)(CNR)] have been synthesized and characterized. The ⁹⁹Tc complexes can be obtained by a two-step reduction/substitution procedure starting from [TcO4]^- via the phosphine-containing precursor complex [Tc(NS3)(PMe2Ph)]. As shown by X-ray structural analyses, the complexes adopt a nearly ideal trigonal-bipyramidal geometry with the trigonal plane formed by the three thiolate sulfurs of the tripodal ligand. The central nitrogen atom of the chelate ligand and the monodendate isocyanides occupy the apical positions. The no-carrier-added preparation of the corresponding ^99mTc complexes was performed by a one-step procedure starting from ^99m[TcO4]^- with stannous chloride as reducing agent. Biodistribution studies in the rat demonstrated for the nonpolar, lipophilic compounds a significant initial brain uptake. In vitro challenge experiments with glutathione clearly indicated that no transchelation reaction occurs. Furthermore, there were no indications for reoxidation of Tc(III) to Tc(V) species or pertechnetate. We propose this type of complexes as a useful tool in the design of lipophilic ^99mTc or ¹⁸⁶Re/¹⁸⁸Re radiopharmaceuticals.

Based on the time on stream dependence of product distribution during deactivation and on additional investigations of fresh and deactivated samples by the homomolecular H–D exchange of molecular hydrogen, it is concluded, that the deactivation during n‐octane dehydrocyclisation on CrOx/La2O3/ZrO2catalysts is caused by a decreasing dehydrogenation capability of the active surface and not by increasing mass transport resistance.

In this paper we present an overview of the application of teletraffic methods for the planning of mobile communication networks. It is shown that there is a necessity for an accurate description of the spatial traffic in order to perform a demand based planning. To accomplish this task, a new traffic demand characterization concept based on a pattern of discretized demand nodes is presented. The spatial traffic distribution also plays an important role when designing networks according to new emerging standards like UMTS. Here, novel analytical models for performance evaluation are required, whether for the examination of the interference limited system capacity or the impacts of variable bit rate voice coding on the transportation over the interconnecting fixed network structure. It is also shown that a spatial characterization of the demand facilitates the application of discrete algorithms for locating base stations.

‘3 + 1’ Oxorhenium(V) complexes [ReO(SN(R')S)(SR)] (R' = Me, Et, Pr or Bu; SR = aminoalkane thiolate) have been synthesized by ligand exchange at trans-trichloromonooxo-bis(triphenylphosphine)rhenium(V) with a mixture of HSN(R')SH and RSH in alkaline methanolic solution. The complexes were purified by column chromatography and characterized by elemental analysis, mass and IR spectroscopy and for selected compounds by ¹H NMR spectroscopy. The structures of those complexes have been determined by X-ray diffraction analysis and revealed a change in the co-ordination geometry from square pyramidal to trigonal bipyramidal, depending on the chelating (SN(R')S) moiety. The alkyl group (R') was found to be arranged “syn” to the oxorhenium group.

To assist in the development of technetium-based radiopharmaceuticals that are useful for the diagnostic imaging of steroid receptor-positive breast tumors, we have synthesized a series of small-sized metal chelates according to ‘n+1’ mixed-ligand, thioether-carbonyl and organometallic designs. In these preliminary investigations, rhenium was used as a model for the radioactive technetium. The metal chelates contain the rhenium metal in several oxidation states, being +5, +3, and +1, and they were attached to 21-substituted progesterone derivatives. A competitive receptor-binding assay (rat uterine cytosol, 0°C) was used to determine the binding affinity of these conjugates for the progesterone receptor. The highest affinity of 9% (RU5020=100%) was obtained with a ‘3+1’ mixed-ligand complex, containing a NMe group as the central donor atom in the tridentate ligand part. This value reflects a relative binding affinity of 75% compared with the parent steroid progesterone.

Abstract:  The monooxo rhenium(V) complexes of cysteine (complex 1) and cysteine methyl ester (complex 2) were synthesised via a ligand exchange reaction starting from gluconatooxorhenium(V). Unexpectedly, the obtained oxorhenium(V) complex with cysteine methyl ester (2) was partially saponified. Both complexes were characterised by common analytical techniques in their solid state. Thus, an octahedral complex structure with 2(NH2,S) co-ordination in the equatorial plane and one carboxyl group bound trans to the oxo group is proven for complex 2 by X-ray diffraction. Furthermore, the existence of a dioxo species at higher pH was proven for the first time with this type of ligand by determining the nearest co-ordination sphere of the rhenium centre in solution at a pH of 12 using extended X-ray absorption fine structure spectroscopy.

Die Reaktion von [ReNCl2(Me2PhP)3] 1mit zwei Äquivalenten Dimercaptobernsteinsäuredimethylester (DMSMe2) in Aceton führt zur Bildung eines neutralen, diamagnetischen Rhenium(V)‐DMSMe2‐Komplexes unter Anlagerung einer Phenyldimethylphosphanisopropyl‐Gruppierung am nukleophilen Nitrid–Stickstoff. Der entstehende Komplex 2[Re{NC(CH3)2(Me2PhP)}(DMSMe2)2] kristallisiert triklin in der Raumgruppe P 1, a = 12,334(7), b = 12,412(7), c = 12,414(8) Å; α = 60,14(3)°, β = 67,98(3)°, γ = 80,63(6)°; Z = 2. Das Rhenium befindet sich in einer quadratisch‐pyramidalen Anordnung der Donoratome. Die beiden meso‐DMSMe2‐Liganden sind in syn‐endo‐Stellung angeordnet. Die Rhenium–Stickstoff‐Bindung ist mit 1,697(12) Å nur wenig länger als in Nitridokomplexen und vergleichbar mit anderen Re–N–C‐Bindungsabständen. Der Angriff des Lösungsmittels am Nitridostickstoffatom wird in Aceton (2) und Methylethylketon unter Bildung von 3beobachtet. Massenspektrometrisch wird darüber hinaus nachgewiesen, daß auch eine Reaktion des Nitridostickstoffatoms mit dem Kondensationsprodukt des Methylethylketons erfolgt unter Bildung von [ReN{C(CH3)(C2H5)CH2C(O)C2H5·(Me2PhP)}(DMSMe2)2] 4.

The crystal structure of (SbCl6C(C6H5)3)2·C6H6 has been determined. It belongs to space groupP21/c, witha=1.765(4),b=.8167(8),c=1.886(3) nm,ß=115.81(3)° andZ=4. We found a host/guest structure with benzene as a guest molecule. The SbCl6 octahedrons are distorted toC4v-symmetry and are arranged in chains alongb, with a charge transfer between them. The propeller structure of the triphenylmethylium is discussed. The distances Cmeth-Cphen are about 0.01 nm shorter than in triphenylmethanes. The IR-spectra of SbCl6 in the crystalline state and in solution are recorded and discussed.

The hydrogen chemisorption on Pt/Al2O3 was investigated by temperature programmed desorption. The activation energy of desorption strongly depends on the hydrogen surface coverage. The chemisorption process is shown to be activated. High temperature H2 desorption (spilled-over hydrogen) is due to reoxidation of reduced parts of the carrier surface by water or -OH groups.

In this wide ranging review the manifold connections between science and the humanities are analysed and a strong plea is made for scientists of all disciplines to learn from the humanities. The review includes such subjects as communicating science, conception of truth, ignorance and knowledge, decision making, scholarship and education, organising research, the role of the media, the question of responsibility, the ethics of nuclear energy, ‘alternative’ scientists, the weighing of decisions and alternatives, and rhetoric, reaching the final conclusion that if the sciences and the humanities are to come closer, then they must continue to ‘talk to each other’.

Radial glial (Müller) cells of the rabbit retina were studied by various techniques including Golgi impregnation, scanning electron microscopy, horseradish peroxidase application, and staining of enzymatically isolated cells. This combination of methods produced detailed information on the specialized morphology of the Müller cells within the different topographical regions of the retina, and of the Müller cell processes within the various retinal layers. As a general rule, the retinal periphery contains short thick Müller cells with big endfeet, whereas the thick central retina is occupied by long slender cells with small endfeet. Independent of their location within the retina, Müller cell processes were found to be adapted to the structure of the surrounding retinal layers. Within the outer and inner nuclear layers, Müller cell processes (and somata) extend thin cytoplasmic “bubbles” ensheathing the neuronal somata, as do the “velate” astrocytes in the brain. In the plexiform layers, Müller cells extend many fine side branches between the neuropil, comparable to the protoplasmic astrocytes of the brain. In the thick myelinated nerve fibre layer of the central retina the Müller cell processes are rather smooth, similar to those of fibrous astrocytes. It is concluded that the neuronal microenvironment determines the morphology of a given glial process, or even of a part of a glial process running through a specialized neuronal compartment.

To achieve desirable decisions from a committee, a novel but dangerous manoeuvre is recommended here: the Chairman to be at the same time also Cook, preparing and serving a superb meal to bring the meeting to a successful conclusion. Theoretical considerations are followed by a detailed description of a meeting-eating.

A series of rhenium complexes was synthesized as model compounds for the corresponding radioactive technetium-99m complexes for preliminary biological investigations. In a ‘3+1’ mixed-ligand approach the tropanol molecule was linked with the metal core through a ω-mercaptoester group as monodentate ligand. Bis(thioethyl)sulphide was used as the tridentate dithiol ligand to block the remaining free coordination sites. The ω-mercaptoesters were synthesized via the trityl-protected precursors. Binding tests on the cloned human dopamine transporter revealed moderate binding affinities for some of the prepared compounds. The complexes were characterised by X-ray and the lipophilicity as well as pKavalues were determined.

Various types of research (application, collection of data using scientific methods, research into the unknown) demand different kinds of promotion (direct external control, research under contract, project research, grant application by the scientist himself, free research), and they demand forms of organization appropiate for the work of individuals, of teams, for the promotion of large groups and sometimes for planning. Persons are always the most important problem; few should remain in the second rank, many should later do something else. Quality and honesty, and their recognition by the public, must remain the fundamental criteria of all research. Growing government influence, with planning and priorities and with a bias towards large projects, should be balanced against a continous effort to maintain and increase the scientific capacity by not neglecting basic research.

Mixed ligand oxorhenium(V) complexes [ReO(SXS)(SeR)] containing terdentate dithiol ligands HS-CH2CH2-X-CH2CH2-SH (HSXSH, X = O,S) and benzeneselenol or benzylselenol, RSeH (R = C6H5, CH2-C6H5) as monodentate ligands have been synthesized and characterized by spectroscopic and X-ray crystallographic methods. X-ray structure analysis of complex 3 (X = O, R = C6H5) shows that the rhenium coordination number is five and the coordination polyhedron is a square pyramid. Structure and spectroscopic data of the complexes are close to those of the corresponding sulphur (RSH as monodentate ligand) compounds.

Reaction of oxorhenium(V) gluconate with D-penicillamine methyl ester (methyl 3-sulfanylvalinate) yielded three neutral 1∶2 complexes. For two complexes (1 and 2) the 1H NMR spectrum in (CD3)2SO shows the presence of a deprotonated and a neutral nitrogen donor group in the ReO(NS)2 system which is an unusual co-ordination mode for bidentate N,S ligands. Complex 1, [ReO{SC(CH3)2CH(CO2CH3)NH2}{SC(CH3)2CH(CO2CH3)NH}], possibly containing in non-co-ordinating solvents an ester oxygen co-ordinated trans to the Re&z.dbd6;O group, is able to bind a water molecule trans to the oxo core to give species 2. In aqueous solution the mixed-ligand complex [ReO{SC(CH3)2CH(CO2CH3)NH2}{SC(CH3)2CH(CO2)NH2}] 3 was unexpectedly formed out of 1 and 2. It contains bidentate D-penicillamine methyl ester and tridentate D-penicillamine in a co-ordination geometry similar to that of the known D-penicillamine complex [ReO{SC(CH3)2CH(CO2H)NH2}{SC(CH3)2CH(CO2)NH2}] 4. Complexes 3 and 4 were structurally characterized by X-ray diffraction.

Reaction of [BzEt3N][ReOCl4] (1) with 0.9 equiv. of 3-thiapentane-1,5-dithiol (HSSSH) in chloroform delivers [ReO(SSS)Cl] (2). The chloro ligand can be substituted by mercaptides whth 2 is heated with an excess of a mercaptane, e.g. C2H5SH, in acetonitrile. Single crystal X-ray analysis of 2 shows square-pyramidal geometry.

The metabolism of dimethoate and its N-butyl homologues in tomato plants has been studied by use of 32P and 35S labelled initial products. The preparation of thiol-35S-labelled dimethoate is described. Formation and break down of dimethoxon and N-tert.-butyl-dimethoxon have been measured by radio-thin layer chromatography. The calculated biological half times have been compared with those in aqueous buffer solutions; remarkable differences between dimethoate and dimethoxon derivatives have been observed. The extension of the N-alkyl chain causes a more rapid biological breakdown. The technique described is also useful for the comparison of other organophosphorus compounds (OPC).