In situ Mechanical Testing Reveals Periodic Buckle Nucleation and Propagation in Carbon Nanotube Bundles

Uniaxial compression studies are performed on 50-µm-diameter bundles of nominally vertical, intertwined carbon nanotubes grown via chemical vapor deposition from a photolithographically defined catalyst. The inhomogeneous microstructure is examined, demonstrating density and tube orientation gradients, believed to play a role in the unique periodic buckling deformation mechanism. Through in situ uniaxial compression experiments it is discovered that the characteristic bottom-to-top sequential buckling proceeds by first nucleating on the bundle surface and subsequently propagating laterally through the bundle, gradually collapsing the entire structure. The effects of strain rate are explored, and storage and loss stiffnesses are analyzed in the context of energy dissipation

Effect of Block Design on Swimming Relay Start Performance

Starting blocks used in competitive swimming often incorporate a wedge for the rear foot to push against when performing flat starts. In most competitions, this wedge cannot be removed so relay starts must be performed with the wedge in place despite the common addition of an approach step during a relay starts. The presence of the wedge constrains the length of the approach step but does provide an inclined surface from which to push which may improve propulsive force development. PURPOSE: The purpose of this study was to evaluate the effect of using a wedge in relay start performance. METHODS: Eight collegiate swimmers (177.69 + 8.73 cm, 74.7 + 9.11 kg, 19.59 + 0.59 years) provided informed consent and completed eight maximal effort relay starts, four with the wedge in place and four without. For all starts, participants were instructed to maintain a streamline position upon entering the water and to glide as far as possible. A relay judging platform was installed on the block and used with an in-water touch pad to measure the exchange time for the relay start. Two synchronized cameras captured movements at 60 Hz above and below water. A 16-point model of the body was used to compute center of mass position for above water movements. Takeoff velocity and angle were defined using the horizontal and vertical velocity of the whole body center of mass. Time to 7m was measured as the time needed for the wrist to reach a point 7m from the pool wall. Paired t-tests were used to compare dependent measures between start conditions. RESULTS: Exchange time (t(7) = 0.11, p = 0.99), takeoff angle (t(7)= 0.60, p = 0.57), and time to 7 m (t(7) = 0.69, p = 0.51) were not different when using the wedge as compared to not using the wedge (Table 1). However, takeoff velocity without the wedge was 2.4% faster (t(7) = 2.48, p = 0.04) than with the wedge on the block (p\u3c0.05). This difference was characterized by a moderate effect size (Cohen d = 0.46). CONCLUSION: Presence of the wedge on the block had a minimal effect on relay start performance. It adversely affected start performance by decreasing takeoff velocity however no other kinematic variables were affected. Having the wedge on the block may constrain the step length of the swimmer during the relay start, which might explain the decrease in velocity

Intranasal Peptide-Based FpvA-KLH Conjugate Vaccine Protects Mice From Pseudomonas aeruginosa Acute Murine Pneumonia

Pseudomonas aeruginosa is an opportunistic pathogen causing acute and chronic respiratory infections associated with morbidity and mortality, especially in patients with cystic fibrosis. Vaccination against P. aeruginosa before colonization may be a solution against these infections and improve the quality of life of at-risk patients. To develop a vaccine against P. aeruginosa, we formulated a novel peptide-based P. aeruginosa subunit vaccine based on the extracellular regions of one of its major siderophore receptors, FpvA. We evaluated the effectiveness and immunogenicity of the FpvA peptides conjugated to keyhole limpet hemocyanin (KLH) with the adjuvant curdlan in a murine vaccination and challenge model. Immunization with the FpvA-KLH vaccine decreased the bacterial burden and lung edema after P. aeruginosa challenge. Vaccination with FpvA-KLH lead to antigen-specific IgG and IgM antibodies in sera, and IgA antibodies in lung supernatant. FpvA-KLH immunized mice had an increase in recruitment of CD11b+ dendritic cells as well as resident memory CD4+ T cells in the lungs compared to non-vaccinated challenged mice. Splenocytes isolated from vaccinated animals showed that the FpvA-KLH vaccine with the adjuvant curdlan induces antigen-specific IL-17 production and leads to a Th17 type of immune response. These results indicate that the intranasal FpvA-KLH conjugate vaccine can elicit both mucosal and systemic immune responses. These observations suggest that the intranasal peptide-based FpvA-KLH conjugate vaccine with curdlan is a potential vaccine candidate against P. aeruginosa pneumonia

Generation of squeezed states of light with a fiber-optic ring interferometer

Forward nondegenerate four-wave mixing in an optical-fiber ring resonator is proposed as a method to generate squeezed states of light. The nonlinear interactions are analyzed both with a self-consistent propagation-equation technique and with Fokker-Planck equations in the Glauber-Sudarshan P representation. Excellent squeezing is predicted at modest input power levels, with perfect quantum-noise squeezing at the critical points for optical bistability. A method to suppress the stimulated Brillouin effect is proposed and demonstrated experimentally, and the effects of forward spontaneous guided acoustic wave Brillouin scattering inside the resonator are analyzed. Methods are suggested for minimizing this noise under conditions where squeezing can be detected. Experimental apparatus and procedures are outlined for verifying the predictions of our theory and demonstrating squeezing of classical and quantum noise

LASSI-L detects early cognitive changes in pre-motor manifest Huntington’s disease: a replication and validation study

Background and objectivesCognitive decline is an important early sign in pre-motor manifest Huntington’s disease (preHD) and is characterized by deficits across multiple domains including executive function, psychomotor processing speed, and memory retrieval. Prior work suggested that the Loewenstein-Acevedo Scale for Semantic Interference and Learning (LASSI-L)–a verbal learning task that simultaneously targets these domains - could capture early cognitive changes in preHD. The current study aimed to replicate, validate and further analyze the LASSI-L in preHD using larger datasets.MethodsLASSI-L was administered to 50 participants (25 preHD and 25 Healthy Controls) matched for age, education, and sex in a longitudinal study of disease progression and compared to performance on MMSE, Trail A & B, SCWT, SDMT, Semantic Fluency (Animals), and CVLT-II. Performance was then compared to a separate age-education matched-cohort of 25 preHD participants. Receiver operating curve (ROC) and practice effects (12 month interval) were investigated. Group comparisons were repeated using a preHD subgroup restricted to participants predicted to be far from diagnosis (Far subgroup), based on CAG-Age-Product scaled (CAPs) score. Construct validity was assessed through correlations with previously established measures of subcortical atrophy.ResultsPreHD performance on all sections of the LASSI-L was significantly different from controls. The proactive semantic interference section (PSI) was sensitive (p = 0.0001, d = 1.548), similar across preHD datasets (p = 1.0), reliable on test–retest over 12 months (spearman rho = 0.88; p = <0.00001) and associated with an excellent area under ROC (AUROC) of 0.855. In the preHD Far subgroup comparison, PSI was the only cognitive assessment to survive FDR < 0.05 (p = 0.03). The number of intrusions on PSI was negatively correlated with caudate volume.DiscussionThe LASSI-L is a sensitive, reliable, efficient tool for detecting cognitive decline in preHD. By using a unique verbal learning test paradigm that simultaneously targets executive function, processing speed and memory retrieval, the LASSI-L outperforms many other established tests and captures early signs of cognitive impairment. With further longitudinal validation, the LASSI-L could prove to be a useful biomarker for clinical research in preHD

Phenoloxidase activity acts as a mosquito innate immune response against infection with semliki forest virus

Several components of the mosquito immune system including the RNA interference (RNAi), JAK/STAT, Toll and IMD pathways have previously been implicated in controlling arbovirus infections. In contrast, the role of the phenoloxidase (PO) cascade in mosquito antiviral immunity is unknown. Here we show that conditioned medium from the Aedes albopictus-derived U4.4 cell line contains a functional PO cascade, which is activated by the bacterium Escherichia coli and the arbovirus Semliki Forest virus (SFV) (Togaviridae; Alphavirus). Production of recombinant SFV expressing the PO cascade inhibitor Egf1.0 blocked PO activity in U4.4 cell- conditioned medium, which resulted in enhanced spread of SFV. Infection of adult female Aedes aegypti by feeding mosquitoes a bloodmeal containing Egf1.0-expressing SFV increased virus replication and mosquito mortality. Collectively, these results suggest the PO cascade of mosquitoes plays an important role in immune defence against arboviruses

TRIM5 Suppresses Cross-Species Transmission of a Primate Immunodeficiency Virus and Selects for Emergence of Resistant Variants in the New Species

Cross-species transmission of simian immunodeficiency virus from sooty mangabeys (SIVsm) into rhesus macaques, and subsequent emergence of pathogenic SIVmac, required adaptation to overcome restriction encoded by the macaque TRIM5 gene

Isolation and Characterization of a Baculovirus Associated with the Insect Parasitoid Wasp, Cotesia marginiventris, or Its Host, Trichoplusia ni

A multiple nucleopolyhedrovirus (MNPV) was isolated from Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae) larvae that had been stung by the parasitoid Cotesia marginiventris (Cresson) (Hymenoptera: Braconidae). The wild type virus was plaque purified by infecting a Heliothis subflexa (BCIRL- HsAM1) cell line and isolating several clones. The mean estimated genomic size of this virus based on PstI, BstEII, StyI, HindIII restriction profiles was estimated to be 106 ± 2.5 kbp (mean±SE). A clone designated as TnMNPV/CmBCL9 was used in bioassays against several lepidopteran pests and in comparative studies with the baculoviruses AcMNPV, AgMNPV, AfMNPV, PxMNPV and HzSNPV of Autographa califomica, Anticarsia gemmatalis, Anagrapha falcifera, Plutella xylostella, and Helicoverpa zea, respectively. Infectivity studies showed that TnMNPV/CmBCL9 was highly infectious for Heliothis subflexa and T. ni, with an LC50 value 0.07 occlusion bodies/mm2 in both species and also infectious for H. zea and Heliothis virescens with LC50 values of 0.22 and 0.27 occlusion bodies/mm2, respectively. Restriction endonuclease analysis of the isolate and selected baculoviruses revealed profiles that were very similar to AfMNPV but different from the restriction endonuclease profiles of the other baculoviruses. Hybridization studies suggest that the TnMNPV/CmBCL9 was closely related to AfMNPV and AcMNPV-HPP. Further support for this comes from a phylogenetic analysis employing a split-graphs network, comparing the polh, egt, and p10 genes from TnMNPV/CmBCL9 with those from other baculoviruses and suggests that this virus is closely related to the AcMNPV variants, AfMNPV and RoMNPV of Rachiplusia ou