Total synthesis and absolute stereochemistry of plakortone D

The first total synthesis of plakortone D is described and thereby establishes the structure and absolute stereochemistry of the most biologically active member of the marine-derived plakortone family. The sterically congested bicyclic lactone core results from a Pd(II)-induced hydroxycyclization−carbonylation−lactonization sequence on an enediol whose chirality was installed by AD-technology. Attachment of the side chain, also constructed using AD-methodology, was achieved by using a modified Julia coupling. The described approach enables acquisition of other plakortones and analogues, in the correct (natural) stereochemical series.

The nexus of value chain integration and e-business applications on public sector agriculture R&D management

We examine the potential impact of interconnectivity of value chain partnerships through electronic means (e-business practices) on the management of Public Sector Agriculture R&D in Australia. We review the changing forms of managing research and development, the forces driving these changes, and R&D processes that are theoretically consistent with the move towards value chain involvement and the increase in active constituents in Public Sector Agriculture R&D. We then explore the potential of emerging e-business models to change the patterns of inter-connectivity, speed and omnipresence of partners in the value chain. Three e-business R&D management practices are identified that provide the prerequisite flexibility necessary to take advantage of opportunistic markets. These R&D business practices are: compressing R&D to reduce time to market, fostering co-development to enter a market at the last moment and building flexible products that allow adjustment at the last possible moment. Some fundamental reallocation of existing resources will be required to meet these markets. Implications of these e-business practices for R&D management are discussed.

Urine D-arabinitol/L-arabinitol ratio in diagnosing Candida infection in patients with haematological malignancy and HIV infection

Adult patients with hematologic malignancies along with HIV infected patients were prospectively studied to determine the performance of urine D-arabinitol/L-arabinitol (DA/LA) ratio in diagnosing invasive candidiasis. Ten evaluable febrile neutropenic patients had proven invasive candidiasis and elevated DA/LA ratios were found in 5. Invasive candidiasis with normal DA/LA ratios was most frequently due to Candida krusei infection. This Candida species is a non-producer of arabinitol. Only 4 of 81 febrile neutropenic patients given either antifungal prophylaxis or empiric antifungal treatment had elevated DA/LA ratios. Only 1 of 15 HIV positive patients with either oropharyngeal or esophageal candidiasis had elevated DA/LA ratios. Widespread use of fluconazole prophylaxis in bone marrow transplantation patients at the study hospital has led to an increased prevalence of C. krusei infection. This is the likely reason for the low sensitivity of the test in proven and suspected invasive Candida infections reported here. (C) 2002 Elsevier Science Inc. All rights reserved.

High resolution 3-D imaging via multi-pass SAR

Spaceborne/airborne synthetic aperture radar (SAR) systems provide high resolution two-dimensional terrain imagery. The paper proposes a technique for combining multiple SAR images, acquired on flight paths slightly separated in the elevation direction, to generate high resolution three-dimensional imagery. The technique could be viewed as an extension to interferometric SAR (InSAR) in that it generates topographic imagery with an additional dimension of resolution. The 3-D multi-pass SAR imaging system is typically characterised by a relatively short ambiguity length in the elevation direction. To minimise the associated ambiguities we exploit the relative phase information within the set of images to track the terrain landscape. The SAR images are then coherently combined, via a nonuniform DFT, over a narrow (in elevation) volume centred on the 'dominant' terrain ground plane. The paper includes a detailed description of the technique, background theory, including achievable resolution, and the results of an experimental study.

Lanczos subspace time-independent wave packet calculations of S(D-1)+H-2 reactive scattering

In this paper. we present the results of quantum dynamical simulations of the S (D-1) + H-2 insertion reaction on a newly developed potential energy surface (J. Chem. Phys. 2001, 114, 320). State-to-state reaction probabilities. product state distributions, and initial-state resolved cumulative reaction probabilities from a given incoming reactant channel are obtained from a time-independent wave packet analysis, performed within a single Lanczos subspace. Integral reaction cross sections are then estimated by J-shifting method and compared with the results from molecular beam experiment and QCT calculations.

Caractéristiques diphasiques des écoulements sur les coursiers en marches d'escalier

Stepped cascades and spillways have been used for more than 3,500 years. The recent regain of interest for the stepped chute design is associated with the introduction of new construction techniques, the development of new design techniques and newer applications. Stepped chute flows are characterised by significant free-surface aeration that cannot be neglected. Two-phase flow measurements were conducted in a large-size model (h =0.10 m, α = 22o). Experimental observations demonstrate the existence of a transition flow regime for a relatively wide range of flow rates. Detailed air-water flow measurements were conducted for both skimming flows and transition flows. Skimming flows exhibit gradual variations of the air-water flow properties, whereas transition flows are characterised by rapid flow redistributions between adjacent steps.

Upstream porthole injection in a 2-D scramjet model

Injection from portholes upstream of the combustion chamber was investigated as a method of delivering fuel into a scramjet. This method reduces the viscous drag on a model by allowing a reduction in the length of the combustion chamber. At experimental enthalpies of 3.0 MJ/kg in the T4 shock tunnel, there was no evidence of combustion in the intake, either by shadowgraph or pressure measurements. Combustion was observed in the combustion chamber. A theoretical extension of these results is made to a hot wall scenario.

Effects of intravenous injection of Clostridium perfringens type D epsilon toxin in calves

In cattle, a neurological lesion similar to that produced in sheep and goats by Clostridium perfringens type D enterotoxaemia has been reported. However, no causal relationship has been established between this disease and the lesion in cattle. The effects of single and multiple intravenous injections of epsilon toxin in three calves aged 6 months were studied. A further calf was inoculated intravenously with saline solution and used as a control. Epsilon toxin invariably produced neurological signs within 2-60 min of the end of the injection process. Clinical signs consisted of loss of consciousness, recumbency, convulsions, paddling, opisthotonus, hyperaesthesia and dyspnoea. Gross changes consisted of severe acute pulmonary oedema, which was particularly marked in the interlobular septa. The histological lesions consisted of intra-alveolar and interstitial oedema of the lung and variable degrees of perivascular proteinaceous oedema in the internal capsule, thalamus and cerebellar white matter. No clinical or post-mortem changes were observed in the control calf. These results show that calves are susceptible to the intravenous injection of epsilon toxin, and that they can show at least some of the histological lesions produced in sheep and goats by this toxin. (C) 2002 Harcourt Publishers Ltd.

Application of the maximum entropy method to the (2 + 1)D four-fermion model

We investigate spectral functions extracted using the maximum entropy method from correlators measured in lattice simulations of the (2+1)-dimensional four-fermion model. This model is particularly interesting because it has both a chirally broken phase with a rich spectrum of mesonic bound states and a symmetric phase where there are only resonances. In the broken phase we study the elementary fermion, pion, sigma, and massive pseudoscalar meson; our results confirm the Goldstone nature of the π and permit an estimate of the meson binding energy. We have, however, seen no signal of σ→ππ decay as the chiral limit is approached. In the symmetric phase we observe a resonance of nonzero width in qualitative agreement with analytic expectations; in addition the ultraviolet behavior of the spectral functions is consistent with the large nonperturbative anomalous dimension for fermion composite operators expected in this model.

Cellular responses to Schistosoma japonicum cathepsin D aspartic protease

Lymphocyte proliferation and cytokine production were measured in groups of mice vaccinated (but not subsequently challenge infected) with recombinant forms of Schistosoma japonicum cathepsin D aspartic protease, rSjASP1 (expressed in bacteria; enzymatically inactive) and rSjASP2 (expressed in insect cells; enzymatically active). Both forms of the schistosome enzyme induced significant proliferation of splenocytes recovered from vaccinated mice, and expression of interferon (IFN)-gamma, interleukin (IL)-4 and IL-10 mRNA in these cells was detected using reverse transcriptase-polymerase chain reaction. Secretion of IFN-gamma, IL-4 and IL-10 by splenocytes from vaccinated mice was confirmed and quantified using enzyme-linked immunosorbent assay. IFN-gamma was the most abundant cytokine produced, followed by IL-4 and IL-10 in rank order. These findings indicated that vaccination of mice with the schistosome protease induces a mixed Th1/Th2 cytokine response, which may explain the modest level of protection after challenge infection in cathepsin d-vaccinated mice, reported previously.

Regulation of the mouse Nas1 promoter by vitamin D and thyroid hormone

The renal sodium-sulfate cotransporter, NaSi-1, a protein implicated to control serum sulfate levels, has been shown to be regulated in vivo by 1,25-dihydroxyvitamin D-3 (1,25-(OH)(2)D-3) and tri-iodothyronine (T-3). Recently, we cloned the mouse NaSi-1 gene (Nas1) and in the present study identified a 1,25-(OH)(2)D-3- and T-3-responsive element located within the Nas1 promoter. Mutational analysis of the Nas1 promoter resulted in identification of a direct repeat 6-type vitamin-D-responsive element (DR6 VDRE) at -525 to -508 and an imperfect inverted repeat 0-type T-3-responsive element (IR0 T3RE) at -436 to -425 which conferred 1,25(OH)(2)D-3 and T3 responsiveness, respectively. In summary, we have identified responsive elements that mediate the enhanced transcription of Nas1 by 1,25-(OH)(2)D-3 and T-3, and these mechanisms may provide important clues to the physiological control of sulfate homeostasis.

Cuticular hydrocarbons of Drosophila birchii and D-serrata: Identification and role in mate choice in D-serrata

The cuticular hydrocarbon compositions of two sympatric species of Australian Drosophila in the montium subgroup of the melanogaster group that use cuticular hydrocarbons in mate recognition have been characterized. Drosophila birchii has 34 components in greater than trace amounts, with a carbon number range of C-20 to C-33. Drosophila serrata has 21 components above trace level and a carbon number range of C-24 to C-31. These two species share eight hydrocarbon components, with all but two of them being monoenes. For both species, the (Z)-9-monoenes are the predominant positional isomer. The hydrocarbons of D. birchii are n-alkanes, n-alkenes (Z)-5-, (Z)-7-, (Z)-9-, and (Z)-11-), low to trace levels of homologous (Z,Z)-7,11- and (Z,Z)-9,13-dienes; and trace amounts of (Z,Z)-5,9- C-25:2, a major component of D. serrata. Only one methyl branched hydrocarbon was detected (2-methyl C-28), and it occurred at very low levels. The hydrocarbons of D. serrata are dominated by a homologous series of (Z,Z)-5,9-dienes, and notably, are characterized by the apparent absence of n-alkanes. Homologous series of (Z)-5-, (Z)-7-, and (Z)-9- alkenes are also present in D. serrata as well as 2-methyl alkanes. Drosophila serrata females display strong directional mate choice based on male cuticular hydrocarbons and prefer D. serrata males with higher relative abundances of the 2-methyl alkanes, but lower relative abundances of (Z,Z)-5,9- C-24:2 and (Z)-9-C-25:1.