GCS support/development system configuration document

The software programming environment used in the development of Guidance and Control Software (GCS) implementations used in a software error studies experiment conducted by the Research Triangle Institute (RTI) and the NASA-Langley is described. The Radio Technical Commission for Aeronautics RTCA/DO-178A guidelines are fulfilled, and requirements for document number 9 in which the hardware, software, and processes used to develop and maintain the software for the GCS project are described. The software programming environment for GCS largely consists of tools that are included in Digital Equipment Corporations software layered product library or are a part of the VAX/VMS baseline system

Software requirements: Guidance and control software development specification

The software requirements for an implementation of Guidance and Control Software (GCS) are specified. The purpose of the GCS is to provide guidance and engine control to a planetary landing vehicle during its terminal descent onto a planetary surface and to communicate sensory information about that vehicle and its descent to some receiving device. The specification was developed using the structured analysis for real time system specification methodology by Hatley and Pirbhai and was based on a simulation program used to study the probability of success of the 1976 Viking Lander missions to Mars. Three versions of GCS are being generated for use in software error studies

GCS programmer's manual

A variety of instructions to be used in the development of implementations of software for the Guidance and Control Software (GCS) project is described. This document fulfills the Radio Technical Commission for Aeronautics RTCA/DO-178A guidelines, 'Software Considerations in Airborne Systems and Equipment Certification' requirements for document No. 4, which specifies the information necessary for understanding and programming the host computer, and document No. 12, which specifies the software design and implementation standards that are applicable to the software development and testing process. Information on the following subjects is contained: activity recording, communication protocol, coding standards, change management, error handling, design standards, problem reporting, module testing logs, documentation formats, accuracy requirements, and programmer responsibilities

Use of island and mainland shorelines by woodland caribou during the nursery period in two northern Ontario parks

Predation is considered a primary limiting factor of woodland caribou (Rangifer tarandus caribou) populations across North America. Caribou are especially vulnerable to predation during their first few weeks of life and have evolved space-use strategies to reduce predation risk through habitat selection during the critical calving and nursery period. We assessed landscape-scale physical characteristics and landcover types associated with caribou nursery sites in Wabakimi and Woodland Caribou Provincial Parks in northern Ontario to better understand nursery site selection in relatively undisturbed landscapes. Although free from industrial activity, these protected areas may subject caribou to human recreational disturbance, so our secondary objective was to evaluate female caribou nursery site selection relative to human recreational activities. We determined that parturient caribou selected landscape characteristics at multiple spatial scales that may reduce predation risk during the calving and nursery period. Generally, female caribou in both parks selected larger lakes with larger than average sized islands configured within shorter than average distances to other islands or landforms that might facilitate escape from predators. The majority of caribou nursery areas in both parks occurred on islands rather than the mainland shoreline of lakes that were surveyed. The nearest landform for escape from these nursery sites on islands was typically another island, and most often 2-3 islands, suggesting parturient caribou may choose islands clustered together as part of their escape strategy. In Woodland Caribou Provincial Park, caribou nursery sites occurred more often in coniferous landcover than expected from availability, while in Wabakimi Provincial Park caribou used sparse, mixed and coniferous forests for nursery activity. Caribou cow-calf pairs typically used areas for nursery activity that were 9.1 km (± 1.0 km, range 2.3-20.6 km) in Wabakimi Provincial Park and 10.2 km (± 0.7 km, range 0.7-32.6 km) in Woodland Caribou Provincial Park from any human recreational disturbance. These landscape-scale physical characteristics and landcover types associated with caribou nursery sites may be used to predict locations of potential caribou nursery areas both outside and within protected areas for the provision of adequate protection and to ensure the persistence of this valued species

Cell Wall N-Linked Mannoprotein Biosynthesis Requires Goa1p, a Putative Regulator of Mitochondrial Complex I in Candida Aabicans

This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The Goa1p of Candida albicans regulates mitochondrial Complex I (CI) activities in its role as a putative CI accessory protein. Transcriptional profiling of goa1Δ revealed a down regulation of genes encoding β-oligomannosyl transferases. Herein, we present data on cell wall phenotypes of goa1Δ (strain GOA31). We used transmission electron microscopy (TEM), GPC/MALLS, and NMR to compare GOA31 to a gene-reconstituted strain (GOA32) and parental cells. We note by TEM a reduction in outer wall fibrils, increased inner wall transparency, and the loss of a defined wall layer close to the plasma membrane. GPC-MALLS revealed a reduction in high and intermediate Mw mannan by 85% in GOA31. A reduction of β-mannosyl but not α-mannosyl linkages was noted in GOA31 cells. β-(1,6)-linked glucan side chains were branched about twice as often but were shorter in length for GOA31. We conclude that mitochondrial CI energy production is highly integrated with cell wall formation. Our data also suggest that not all cell wall biosynthetic processes are dependent upon Goa1p even though it provides high levels of ATP to cells. The availability of both broadly conserved and fungal-specific mutants lacking CI subunit proteins should be useful in assessing functions of fungal-specific functions subunit proteins

Science exploration opportunities for manned missions to the Moon, Mars, Phobos, and an asteroid

Scientific exploration opportunities for human missions to the Moon, Phobos, Mars, and an asteroid are addressed. These planetary objects are of prime interest to scientists because they are the accessible, terresterial-like bodies most likely to be the next destinations for human missions beyond Earth orbit. Three categories of science opportunities are defined and discussed: target science, platform science, and cruise science. Target science is the study of the planetary object and its surroundings (including geological, biological, atmospheric, and fields and particle sciences) to determine the object's natural physical characteristics, planetological history, mode of origin, relation to possible extant or extinct like forms, surface environmental properties, resource potential, and suitability for human bases or outposts. Platform science takes advantage of the target body using it as a site for establishing laboratory facilities and observatories; and cruise science consists of studies conducted by the crew during the voyage to and from a target body. Generic and specific science opportunities for each target are summarized along with listings of strawman payloads, desired or required precursor information, priorities for initial scientific objectives, and candidate landing sites. An appendix details the potential use of the Moon for astronomical observatories and specialized observatories, and a bibliography compiles recent work on topics relating to human scientific exploration of the Moon, Phobos, Mars, and asteroids. It is concluded that there are a wide variety of scientific exploration opportunities that can be pursued during human missions to planetary targets but that more detailed studies and precursor unmanned missions should be carried out first

New Insights into the Structure of (1→3,1→6)-β-D-Glucan Side Chains in the Candida glabrata Cell Wall

β-glucan is a (1→3)-β-linked glucose polymer with (1→6)-β-linked side chains and a major component of fungal cell walls. β-glucans provide structural integrity to the fungal cell wall. The nature of the (1–6)-β-linked side chain structure of fungal (1→3,1→6)-β-D-glucans has been very difficult to elucidate. Herein, we report the first detailed structural characterization of the (1→6)-β-linked side chains of Candida glabrata using high-field NMR. The (1→6)-β-linked side chains have an average length of 4 to 5 repeat units spaced every 21 repeat units along the (1→3)-linked polymer backbone. Computer modeling suggests that the side chains have a bent curve structure that allows for a flexible interconnection with parallel (1→3)-β-D-glucan polymers, and/or as a point of attachment for proteins. Based on these observations we propose new approaches to how (1→6)-β-linked side chains interconnect with neighboring glucan polymers in a manner that maximizes fungal cell wall strength, while also allowing for flexibility, or plasticity

Mannan Molecular Substructures Control Nanoscale Glucan Exposure in Candida

Cell wall mannans of Candida albicans mask β-(1,3)-glucan from recognition by Dectin-1, contributing to innate immune evasion. Glucan exposures are predominantly single receptor-ligand interaction sites of nanoscale dimensions. Candida species vary in basal glucan exposure and molecular complexity of mannans. We used super-resolution fluorescence imaging and a series of protein mannosylation mutants in C. albicans and C. glabrata to investigate the role of specific N-mannan features in regulating the nanoscale geometry of glucan exposure. Decreasing acid labile mannan abundance and α-(1,6)-mannan backbone length correlated most strongly with increased density and nanoscopic size of glucan exposures in C. albicans and C. glabrata, respectively. Additionally, a C. albicans clinical isolate with high glucan exposure produced similarly perturbed N-mannan structures and elevated glucan exposure geometry. Thus, acid labile mannan structure influences the nanoscale features of glucan exposure, impacting the nature of the pathogenic surface that triggers immunoreceptor engagement, aggregation, and signaling. Graus et al. find that N-mannan structural features regulated by Candida mannosyltransfersases control glucan exposure. Loss of mannan increased the frequency and size of glucan exposures and changed multivalent receptor engagement. Changes to mannan structure in a bloodstream isolate are associated with elevated glucan exposure at the nanoscale

Carbohydrates from Pseudomonas aeruginosa biofilms interact with immune C-type lectins and interfere with their receptor function

Bacterial biofilms represent a challenge to the healthcare system because of their resilience against antimicrobials and immune attack. Biofilms consist of bacterial aggregates embedded in an extracellular polymeric substance (EPS) composed of polysaccharides, nucleic acids and proteins. We hypothesised that carbohydrates could contribute to immune recognition of Pseudomonas aeruginosa biofilms by engaging C-type lectins. Here we show binding of Dendritic Cell-Specific Intercellular adhesion molecule-3-Grabbing Non-integrin (DC-SIGN, CD209), mannose receptor (MR, CD206) and Dectin-2 to P. aeruginosa biofilms. We also demonstrate that DC-SIGN, unlike MR and Dectin-2, recognises planktonic P. aeruginosa cultures and this interaction depends on the presence of the common polysaccharide antigen. Within biofilms DC-SIGN, Dectin-2 and MR ligands appear as discrete clusters with dispersed DC-SIGN ligands also found among bacterial aggregates. DC-SIGN, MR and Dectin-2 bind to carbohydrates purified from P. aeruginosa biofilms, particularly the high molecular weight fraction (HMW; >132,000 Da), with KDs in the nM range. These HMW carbohydrates contain 74.9–80.9% mannose, display α-mannan segments, interfere with the endocytic activity of cell-associated DC-SIGN and MR and inhibit Dectin-2-mediated cellular activation. In addition, biofilm carbohydrates reduce the association of the DC-SIGN ligand Lewisx, but not fucose, to human monocyte-derived dendritic cells (moDCs), and alter moDC morphology without affecting early cytokine production in response to lipopolysaccharide or P. aeruginosa cultures. This work identifies the presence of ligands for three important C-type lectins within P. aeruginosa biofilm structures and purified biofilm carbohydrates and highlights the potential for these receptors to impact immunity to P. aeruginosa infection