Excitations of Bose Fluids in Nanotubes

We discuss the excitation spectra of Bose fluids in the quasi-one dimensional geometries which can be found in interstitial channels of nanotubes and inside individual nanotubes. We compute the collective excitations of the fluids adsorbed in these environments, using alternative models, and show that the heat capacity remains sufficiently large to be easily measured.     

Characterization of the hemodynamic response to intravenous diaspirin crosslinked hemoglobin solution in rats

Diaspirin crosslinked hemoglobin solution (DCLHB) has potential for clinical use as an oxygen-carrying solution because of its excellent oxygen transport properties and biochemical stability. The present study characterizes the effects of intravenous infusions of 0.625-40 mL/kg (62.5-4000 mg/kg) DCLHb on mean blood pressure (MAP) and heart rate (HR) in conscious rats. DCLHb at all doses tested except 62.5 mg/kg was associated with an immediate increase in MAP (25-30% above baseline) that peaked between 20-30 minutes after infusion and returned to baseline within 120-300 minutes in a dose-dependent manner. Maximum MAP achieved was in the range of 129 +/- 7 to 140 +/- 7 mm Hg and there was no statistically significant difference in the response between doses. HR responded in a reciprocal manner to changes in MAP. Volume- and oncotic-matched infusions of LR and albumin did not alter MAP or HR. Slow infusion (0.34 mL/min) of DCLHb appeared to blunt the magnitude of the pressor response when compared to bolus injection (< 10 sec). DCLHb administration is associated with a pressor response that is not due to volume load, oncotic pressure, or rate of infusion, suggesting that it is intrinsic to the modified hemoglobin molecule and pharmacologic in nature.     

Nucleocytoplasmic transport: driving and directing transport

Nucleocytoplasmic transport involves assembly and movement across the nuclear envelope of cargo-receptor complexes that interact with the small GTPase Ran. The asymmetric distribution of Ran regulator proteins, RanGAP1 and RCC1, provides the driving force and directionality for nuclear transport.     

Radiographic evaluation of osseous displacement following intra-articular fractures of the distal radius: reliability of plain radiography versus computed tomography

This study evaluated the reliability of plain radiography versus computed tomography (CT) for the measurement of small (< 5 mm) intra-articular displacements of distal radius fracture fragments. The plain radiographs and CT scans of 19 acute intra-articular distal radius fractures were used by 5 independent observers, using 2 standardized techniques, to quantify incongruity of the articular surface in a blinded and randomized fashion. Repeat measurements were performed by the same observers 2-4 weeks later, allowing determination of intraclass correlation coefficients (ICC) as a measure of intraobserver and interobserver agreement. The average maximum gap displacement on plain radiographs was 2.1 mm (range, 0.0-15.0 mm, lateral view) and on CT images was 4.9 mm (range, 0.7-17.3 mm, axial view). The average maximum step displacement on plain radiographs was 0.9 mm (range, 0.0-6.4 mm, lateral view) and on CT images was 1.2 mm (range, 0.0-6.0 mm, sagittal view). More reproducible values determining step and gap displacement were obtained when the arc method of measurement was used on CT scans (ICC values, .69-.97) as compared to the longitudinal axis method for plain radiographs (ICC values, .30-.50). For measured displacements of 2 mm or more, our data demonstrated poor correlation between measurements made on CT images and those made on plain radiographs (gap or step displacement > 2 mm, K = 0.21; step displacement > 2 mm, K = 0.21). Thirty percent of measurements from plain radiographs significantly underestimated or overestimated displacement compared to CT scan measurements. From these data, we conclude that CT scanning data, using the arc method of measurement, are more reliable for quantifying articular surface incongruities of the distal radius than are plain radiography measurements.     

Effects of overexpression of the alkyl hydroperoxide reductase AhpC on the virulence and isoniazid resistance of Mycobacterium tuberculosis

Mutations to the regulatory region of the ahpC gene, resulting in overproduction of alkyl hydroperoxide reductase, were encountered frequently in a large collection of isoniazid (INH)-resistant clinical isolates of Mycobacterium tuberculosis but not in INH-susceptible strains. Overexpression of ahpC did not seem to be important for INH resistance, however, as most of these strains were already defective for catalase-peroxidase, KatG, the enzyme required for activation of INH. Transformation of the INH-susceptible reference strain, M. tuberculosis H37Rv, with plasmids bearing the ahpC genes of M. tuberculosis or M. leprae did not result in a significant increase in the MIC. Two highly INH-resistant mutants of H37Rv, BH3 and BH8, were isolated in vitro and shown to produce no or little KatG activity and, in the case of BH3, to overproduce alkyl hydroperoxide reductase as the result of an ahpC regulatory mutation that was also found in some clinical isolates. The virulence of H37Rv, BH3, and BH8 was studied intensively in three mouse models: fully immunocompetent BALB/c and Black 6 mice, BALB/c major histocompatibility complex class II-knockout mice with abnormally low levels of CD4 T cells and athymic mice producing no cellular immune response. The results indicated that M. tuberculosis strains producing catalase-peroxidase were considerably more virulent in immunocompetent mice than the isogenic KatG-deficient mutants but that loss of catalase-peroxidase was less important when immunodeficient mice, unable to produce activated macrophages, were infected. Restoration of virulence was not seen in an INH-resistant M. tuberculosis strain that overexpressed ahpC, and this finding was confirmed by experiments performed with appropriate M. bovis strains in guinea pigs. Thus, in contrast to catalase-peroxidase, alkyl hydroperoxide reductase does not appear to act as a virulence factor in rodent infections or to play a direct role in INH resistance, although it may be important in maintaining peroxide homeostasis of the organism when KatG activity is low or absent.     

Six month follow-up: the crucial test of multidisciplinary developmental assessment

Participation of parents in the developmental assessment process is thought to be beneficial in promoting understanding of their child's disability, and improving consensus between parents and professionals about appropriate intervention programmes. If costly multidisciplinary assessments are to be justified, it is necessary to establish long-term benefits for the child. This highlights a need for research identifying how families use services after diagnostic assessment and what they understand to be important for their child. Poor parent-professional agreement about diagnosis may be a factor contributing to low compliance with recommendations. The major purpose of the current study was to follow-up families 6 months after developmental assessment, in order to investigate use of recommended intervention services. In addition, mothers' opinions about diagnostic findings, recommendations and early intervention services were examined. Subjects were 40 pre-school children who presented for developmental assessment, and their mothers. The majority were diagnosed with developmental problems in multiple domains. Results indicated that most mothers recalled and agreed with their child's diagnosis, but underestimated the severity of developmental delay. Families had not accessed the range of multidisciplinary intervention programmes recommended, given the complexity of their children's disabilities. Speech therapy was considered the service of highest priority by mothers, and was the treatment most frequently received. Mothers recognized a need for more therapeutic interventions for their child. An unexpected finding was the high prevalence of families who organized nonprescribed therapies. Possible explanations of the findings and implications for service delivery are discussed.     

Molecular-beam epitaxy of InTlAs

We have investigated growth of InTlAs and TlAs by molecular-beam epitaxy (MBE) onto both InAs-buffered and unbuffered GaAs substrates. In accordance with more recent predictions by the theorists who originally proposed InTlAs and two other related thallium-based compounds for long-wave infrared applications, we have observed experimentally that incorporation of thallium into InTlAs is indeed difficult by MBE. In fact, to date we have found a possible hint of appreciable InTlAs formation in only one of our attempted growths: one which was conducted at a growth temperature around 420°C on a highly defective InAs buffer. However, TlAs formation (although highly defective) was apparently obtained at a growth temperature around 200°C on a good InAs buffer. Moreover, although Tl has proven to be very difficult to incorporate into InTlAs by MBE, we have discovered that the presence of a Tl flux during InAs growth consistency permits good growth of InAs, even at growth temperatures far below those normally optimal for InAs MBE.     

Chlamydomonas kinesin-II-dependent intraflagellar transport (IFT): IFT particles contain proteins required for ciliary assembly in Caenorhabditis elegans sensory neurons

We previously described a kinesin-dependent movement of particles in the flagella of Chlamydomonas reinhardtii called intraflagellar transport (IFT) (Kozminski, K.G., K.A. Johnson, P. Forscher, and J.L. Rosenbaum. 1993. Proc. Natl. Acad. Sci. USA. 90:5519-5523). When IFT is inhibited by inactivation of a kinesin, FLA10, in the temperature-sensitive mutant, fla10, existing flagella resorb and new flagella cannot be assembled. We report here that: (a) the IFT-associated FLA10 protein is a subunit of a heterotrimeric kinesin; (b) IFT particles are composed of 15 polypeptides comprising two large complexes; (c) the FLA10 kinesin-II and IFT particle polypeptides, in addition to being found in flagella, are highly concentrated around the flagellar basal bodies; and, (d) mutations affecting homologs of two of the IFT particle polypeptides in Caenorhabditis elegans result in defects in the sensory cilia located on the dendritic processes of sensory neurons. In the accompanying report by Pazour, G.J., C.G. Wilkerson, and G.B. Witman (1998. J. Cell Biol. 141:979-992), a Chlamydomonas mutant (fla14) is described in which only the retrograde transport of IFT particles is disrupted, resulting in assembly-defective flagella filled with an excess of IFT particles. This microtubule- dependent transport process, IFT, defined by mutants in both the anterograde (fla10) and retrograde (fla14) transport of isolable particles, is probably essential for the maintenance and assembly of all eukaryotic motile flagella and nonmotile sensory cilia.     

CLOSURE IN COLE'S REFORMULATED LEONTIEF MODEL: A Response to R. W. Jackson, M. Madden, and H. A. Bowman

ABSTRACT My paper The delayed impacts of plant closures in a reformulated Leontief model showed that the time-varying impacts of changes to a regional economy could be approximated usefully by a simple elaboration of the Leontief inverse (Cole, 1988). I have applied the method in a variety of situations, typically to calculate the shifts in community income and its distribution following a major catastrophe. In all cases I use a single or multi-region social accounting matrix. Since Jackson et al (1997) have been unable to reproduce my results I shall begin with a step-by-step demonstration. Then I shall show that their failure lies in their treatment of the external (rest-of- world) sector. This appears to arise from their overly restrictive definition of input-output analysis in relation to other types of model, and their confusion as to the difference between simplification, approximation, and model validation.     

Universal Anisotropic Condensation Transition of Gases in Nanotube Bundles

Gases adsorbed within bundles of carbon nanotubes (inside of the nanotubes or in the interstitial channels between the tubes) exhibit a variety of phase transitions with the help of interactions between molecules in neighboring channels or tubes. Because the channels/tubes are widely separated, these transverse interactions are weaker than the (longitudinal) interactions within the same channel. The transition temperatures that result are therefore lower than those of typical two- or three-dimensional transitions of the same species of molecules. We discuss here the condensation transition of such a gas to form a liquid, expressing the transition behavior in universal form, where the reduced critical temperature T ^* _c is a universal function of the reduced transverse interaction.