Investigating proactive balance control in individuals with incomplete spinal cord injury while walking on a known slippery surface

BACKGROUND: Falls are a growing concern among individuals with incomplete spinal cord injury (iSCI). As many as 83% of individuals with iSCI experience at least one fall per year. Most outdoor falls occur while walking on uneven or slippery surfaces. Individuals with iSCI employ proactive balance strategies to a greater extent than able-bodied (AB) individuals during normal walking, which is effective in reducing the intensity of an unexpected slip. Whether individuals with iSCI can use proactive balance strategies in a feedforward manner to adapt to expected slip perturbations and reduce slip/fall potential while walking has not been assessed. METHODS:19 individuals with iSCI (AIS D; 14 males; 61.01 ± 17.67 years) and 17 age- and sex-matched AB individuals (13 males; 60.86 ± 17.79 years) were included in the study. Low-friction steel rollers were used to induce a slip in the anterior-posterior (AP) direction. Participants completed three walking conditions: normal walking trials (NW), one unexpected slip trial (US), and four expected slip (ES) trials. Changes in kinematic and electromyography (EMG) data were analyzed to give an indication of feedforward adaptations to the slip. Outcome variables included step width, step length, center of mass (COM) velocity, foot-floor angle, medial-lateral and AP margin of stability (MOS), maximum post-slip velocity (PSV), and integrated EMG for tibialis anterior (TA), soleus (SOL), and gluteus RESULTS: Individuals with iSCI used feedforward behavioural strategies to a greater extent than AB individuals while approaching a known slippery surface including walking with shorter steps, a flatter foot-floor angle, a more anteriorly positioned COM, and slower COM velocity. AB and iSCI groups made similar changes in their muscle activity to proactively prepare for the ES trials. The main difference between groups was a reduced ability of individuals with iSCI to proactively modulate the amplitude of the trail SOL muscle compared to AB individuals. Both AB and iSCI groups were able to make significant feedforward adjustments to behaviour and muscle activity within 1-2 trials after experiencing an US. These proactive balance strategies were effective at reducing the maximum PSV and thus the slip/fall potential in both groups. CONCLUSIONS: Results demonstrate that individuals with iSCI maintain the ability to make appropriate feedforward changes in behavior and muscle activity and do so in a similar manner to AB individuals

Titan 3E/Centaur D-1T Systems Summary

A systems and operational summary of the Titan 3E/Centaur D-1T program is presented which describes vehicle assembly facilities, launch facilities, and management responsibilities, and also provides detailed information on the following separate systems: (1) mechanical systems, including structural components, insulation, propulsion units, reaction control, thrust vector control, hydraulic systems, and pneumatic equipment; (2) astrionics systems, such as instrumentation and telemetry, navigation and guidance, C-Band tracking system, and range safety command system; (3) digital computer unit software; (4) flight control systems; (5) electrical/electronic systems; and (6) ground support equipment, including checkout equipment

IMMUNOLOGY AND VACCINOLOGY OF HUMAN PAPILLOMAVIRUS MINOR CAPSID PROTEIN L2

Human papillomavirus (HPV) minor capsid protein L2 has potential in being a broad spectrum protective yet low cost vaccine that is needed to eliminate HPV-related cancer as a global health problem. Several L2-based vaccines designed to induce broadly neutralizing serum antibodies are nearing phase 1 clinical trials to assess their safety and immunogenicity. Therefore, robust tools for serological assessment of L2-specific antibody responses to infection and vaccination are required. Presently, HPV neutralizing antibodies are measured in vitro using HPV Pseudovirions that deliver a reporter plasmid rather than an infectious genome. However the current assays are either cumbersome or lack sensitivity for L2-specific neutralizing antibodies because they do not fully replicate in vitro the slow but critical cleavage of L2 by furin observed in vivo. To address this issue, we developed a high-throughput in vitro neutralization assay based on a furin-cleaved infectious intermediate and validated it as sensitive measure for both HPV L1 and L2-specific neutralizing antibodies of both human and animal origin. We also generated two human chimeric antibodies for use as a standard and/or positive control necessary for validation of immunogenicity studies of planned clinical trials of L2-based vaccines. Further mechanistic studies of L2-antibody mediated protection against experimental viral challenge demonstrated the importance of the Fc region of the antibody in mediating phagocyte recognition of virions. Finally, because vaccination against L2 alone does not provide therapeutic benefit against established infection, L2 was fused with early viral antigens as an approach to combine therapy and protective immunity. Orthotopic tumor lines, such as the TC-1 cell line generated by ectopic expression of HPV16 E6 and E7 and mutant ras in C57BL6 mouse lung fibroblasts, have been utilized to assay therapeutic immunity. However, these lines do not emulate the viral life cycle or papilloma development. Given the tractability of mouse models and a plethora of reagents, we have exploited a recently identified laboratory mouse papillomavirus model (MusPV1) and pseudovirion challenge studies to demonstrate the potential of E6E7L2 fusion vaccines to prevent new infections and for the treatment of established papillomavirus infection or disease

Advanced information processing system: The Army fault tolerant architecture conceptual study. Volume 2: Army fault tolerant architecture design and analysis

Described here is the Army Fault Tolerant Architecture (AFTA) hardware architecture and components and the operating system. The architectural and operational theory of the AFTA Fault Tolerant Data Bus is discussed. The test and maintenance strategy developed for use in fielded AFTA installations is presented. An approach to be used in reducing the probability of AFTA failure due to common mode faults is described. Analytical models for AFTA performance, reliability, availability, life cycle cost, weight, power, and volume are developed. An approach is presented for using VHSIC Hardware Description Language (VHDL) to describe and design AFTA's developmental hardware. A plan is described for verifying and validating key AFTA concepts during the Dem/Val phase. Analytical models and partial mission requirements are used to generate AFTA configurations for the TF/TA/NOE and Ground Vehicle missions

Manipulation of gene expression in early mouse embryo

Maternal (oocyte) and embryonic programmes of hypoxanthine phosphoribosyl transferase (HPRT) and adenine phosphoribosyl transferase (APRT) gene expression have been investigated in mouse oocytes and during preimplantation development. The onset of the embryonic HPRT gene occurs following fertilization, or parthenogenetic activation, before the 4-cell stage. The oocyte-determined increase in HPRT activity due to preformed mRNA continues in aging oocytes, as well as in fertilized or activated eggs, i.e. irrespective of the initiation of embryonic development. Attempts were made to determine whether there is a detectable time difference in the onset of maternal and paternal genomes by assaying the onset of embryo- coded HPRT activity in embryos of different maternal and paternal X-chromosome constitution, but due to difficulties in comparable staging of embryos, no definite conclusion could be drawn. The expression of an exogenously introduced HPRT minigene has been monitored throughout preimplantation development. The embryos injected with supercoiled HPRT minigene showed an approximately twofold increase in HPRT activity at the 2-cell stage compared with control uninjected embryos. Linear minigene DNA was less efficient in giving active enzyme. The efficacy of three different promoters were studied in 2-cell mouse embryos using the expression of the HPRT minigene as a reporter function. The mouse HPRT promoter and the uninduced mouse metallothionein-1 (MT-1) promoter functioned equally well whereas the viral SV40 promoter did not allow HPRT expression. The mouse MT-1 promoter linked to the HPRT minigene allowed induction of HPRT gene expression in mouse embryos cultured in the presence of cadmium. The inhibition of enzyme expression from injected minigene DNA is mediated by simultaneous injection of a fivefold molar excess of HPRT antisense DNA. The same negation of exogenous HPRT activity was observed with simultaneous injection of HPRT exon-1 antisense DNA. The use of an inducible HPRT antisense construct achieved repression of gene activity with equivalent molar amounts of antisense to the sense molecules. Transgenic mice were produced with an antisense HPRT minigene construct attached to the inducible mouse MT-l promoter. The prospect of "cancelling" the endogenous "sense" gene activity in these mice at a specific stage of development by applying the induction stimulus is discussed

Evolution and ecology of two iconic Australian clades: the Meliphagidae (birds) and the Hakeinae (plants)

The first part of this dissertation explores the evolution of two iconic groups of species through Australian climate space: the Meliphagidae, or honeyeaters, which are primarily nectar-feeding birds, and the Hakeinae, a section of the plant family Proteaceae. Both groups are inferred to have had their origins in Gondwanan rainforests that were widespread across Australia 45 million years ago and then diversified into more arid environments as the continent’s climate became more arid. Accordingly, dry environments are inhabited by closely related (phylogenetically clustered) sets of species, although, in contrast to the honeyeaters, Hakeinae communities are characterized by more localized diversification. The impressive and rapid Hakeinae diversification may have been driven by specialization onto a variety of highly weathered, nutrient-poor soil types on the ancient Australian landmass. The second part of this dissertation reviews a variety of methods to assess the phylogenetic structure of communities, such as local assemblages of honeyeaters and Hakeinae. Many published methods were found to be redundant, and some of the truly unique approaches do not measure what they purport to. Accordingly, only a small subset of phylogenetic community structure methods have merit. In the third part of the dissertation, observations on foraging by 74 of 75 Australian honeyeater species are used to explore patterns of community assembly. Australian honeyeater communities reflect both stochastic and deterministic processes. Co-occurring species exhibit substantial overlap in foraging niche space, in contrast to predictions from assembly theory based on competition. At the same time, species tend to occupy characteristic portions of niche space and available niche space is smaller in the arid regions of the continent. Within this smaller available niche space, arid-zone species tend to be more widely separated in niche space than species in more mesic environments

A methodology for the quantitative evaluation of attacks and mitigations in IoT systems

PhD ThesisAs we move towards a more distributed and unsupervised internet, namely through the Internet of Things (IoT), the avenues of attack multiply. To compound these issues, whilst attacks are developing, the current security of devices is much lower than for traditional systems. In this thesis I propose a new methodology for white box behaviour intrusion detection in constrained systems. I leverage the characteristics of these types of systems, namely their: heterogeneity, distributed nature, and constrained capabilities; to devise a pipeline, that given a specification of a IoT scenario can generate an actionable intrusion detection system to protect it. I identify key IoT scenarios for which more traditional black box approaches would not suffice, and devise means to bypass these limitations. The contributions include; 1) A survey of intrusion detection for IoT; 2) A modelling technique to observe interactions in IoT deployments; 3) A modelling approach that focuses on the observation of specific attacks on possible configurations of IoT devices; Combining these components: a specification of the system as per contribution 1 and a attack specification as per contribution 2, we can deploy a bespoke behaviour based IDS for the specified system. This one of a kind approach allows for the quick and efficient generation of attack detection from the onset, positioning this approach as particularly suitable to dynamic and constrained IoT environments

A short upstream promoter region mediates transcriptional regulation of the mouse doublecortin gene in differentiating neurons.

peer reviewedABSTRACT: BACKGROUND: Doublecortin (Dcx), a MAP (Microtubule-Associated Protein), is transiently expressed in migrating and differentiating neurons and thereby characterizes neuronal precursors and neurogenesis in developing and adult neurogenesis. In addition, reduced Dcx expression during development has been related to appearance of brain pathologies. Here, we attempt to unveil the molecular mechanisms controlling Dcx gene expression by studying its transcriptional regulation during neuronal differentiation. RESULTS: To determine and analyze important regulatory sequences of the Dcx promoter, we studied a putative regulatory region upstream from the mouse Dcx coding region (pdcx2kb) and several deletions thereof. These different fragments were used in vitro and in vivo to drive reporter gene expression. We demonstrated, using transient expression experiments, that pdcx2kb is sufficient to control specific reporter gene expression in cerebellar cells and in the developing (E14.5) brain. We determined the temporal profile of Dcx promoter activity during neuronal differentiation of mouse embryonic stem cells (mESC) and found that transcriptional activation of the Dcx gene varies along with neuronal differentiation of mESC. Deletion experiments and sequence comparison of Dcx promoters across rodents, human and chicken revealed the importance of a highly conserved sequence in the proximal region of the promoter required for specific and strong expression in neuronal precursors and young neuronal cells. Further analyses revealed the presence in this short sequence of several conserved, putative transcription factor binding sites: LEF/TCF (Lymphoid Enhancer Factor/T-Cell Factor) which are effectors of the canonical Wnt pathway; HNF6/OC2 (Hepatocyte Nuclear Factor-6/Oncecut-2) members of the ONECUT family; and NF-Y/CAAT (Nuclear Factor-Y). CONCLUSIONS: Studies of Dcx gene regulatory sequences using native, deleted and mutated constructs suggest that fragments located upstream of the Dcx coding sequence are sufficient to induce specific Dcx expression in vitro: in heterogeneous differentiated neurons from mESC, in primary mouse cerebellar neurons (PND3) and in organotypic slices cultures. Furthermore, a region in the 3'-end region of the Dcx promoter is highly conserved across several species and exerts positive control on Dcx transcriptional activation. Together, these results indicate that the proximal 3'-end region of the mouse Dcx regulatory sequence is essential for Dcx gene expression during differentiation of neuronal precursors

The autonomy and function of eukaryotic signal sequences : segregation of variants of preprochymosin and prelysozyme in "Xenopus oocytes" and "in vitro"

Cloned complementary DNAs encoding the secretory proteins chick prelysozyme and calf preprochymosin were inserted downstream from various viral promoters in modified recombinant “shuttle" vectors. The microinjection of these constructs into the nuclei of Xenopus laevis oocytes resulted in the efficient expression of lysozyme and prochymosin proteins which were segregated into membranes and secreted by the oocyte. The signal sequences of the proteins were correctly processed as judged from molecular weight estimations. Injection of DNA encoding prochymosin without its signal sequence resulted in the synthesis of a prochymosin protein which was localised in the oocyte cytoplasm; whereas when DNA encoding mature chymosin was injected no proteins were detected by immunoprécipitation with prochymosin antisera. The same cDNAs were subsequently cloned into SP6 vectors and synthetic, capped RNA was prepared. Following cytoplasmic injection of SP6 RNA into oocytes the same compartmentation of the proteins was observed but again no chymosin protein was detected following injection of RNA encoding mature chymosin, although translation of this RNA in vitro produced a protein with the expected molecular weight of chymosin which was precipitated by prochymosin antisera. The expression of preprochymosin messenger RNA, following cytoplasmic injection into oocytes and also using in vitro translation systems, showed the mRNA encoded two preprochymosin proteins specifically precipitated by prochymosin antisera. In the oocyte both forms were processed, segregated and secreted; whilst in vitro the precursors were cleaved on translocation within dog pancreatic microsomes where they became resistant to digestion by exogenous proteases. The translation of preprochymosin mRNA in vitro has previously been reported to produce only one major polypeptide on gel electrophoresis of products precipitated by antiprochymosin sera. The origin and nature of the two electrophoretically distinct species is not certain; but it was noted that the protein product of the cloned preprochymosin cDNA showed the same mobility on SDS-polyacrylamide gels as the faster migrating species encoded by the mRNA. Two hybrid genes were constructed encoding proteins in which the signal sequence of prelysozyme was replaced with different N-terminal regions of preprochymosin. C₆L contained a fragment from the preprochymosin cDHA which encoded the signal sequence and the first six amino acids of prochymosin; this was fused to codons 8 to 129 of mature lysozyme. The second construct C₆₂L carried a larger portion of preprochymosin, up to codon 62 of prochymosin, with the same C-terminal region of lysozyme. These fusions showed poor and variable expression following nuclear injection of the hybrid genes contained in the shuttle vector. However cytoplasmic injection of the corresponding SP6 RNAs demonstrated that both fusion proteins were synthesized in the oocyte and segregated into membranes, but did not get secreted from the oocyte. The distribution of C₆₂L protein within the oocyte corresponded with that observed for the majority of other secretory proteins including preprochymosin, with most protein fractionating with vesicles. In contrast C₆L displayed the anomalous fractionation previously observed for lysozyme, with approximately equal amounts of the processed protein fractionating with the cytoplasm and the membranes. Relative to the precursor polypeptides produced by in vitro translation of the SP6 RNAs for C₆L and C₆₂L, the respective proteins expressed in oocytes each showed an increased mobility on electrophoresis consistent with the cleavage of the signal peptide. The same processing of the preC₆L and preC₆₂L proteins was observed when in vitro translation was carried out In the presence of pancreatic mlcro6omes. The observed compartmentation and processing of these hybrid proteins Indicates that a eukaryotic signal sequence functions autonomously in Initiating the translocation of secretory proteins, but that other properties of the protein conformation are necessary to achieve subsequent secretion