Group M: ARLISS Canister Vehicle

This project is a dicycle designed for the ARLISS Canister Competition. In this competition, the device is loaded into a rocket which is then launched to about 12000 ft before releasing the device. Then it must safely land and autonomously navigate to a predetermined GPS location on the ground. Due to the fact that this is a mechanical engineering design project and the time restrictions of this class, we focused on the physical aspect of the project, such as building a device that can survive the launch and landing and traverse several kilometers through the desert, forgoing the autonomous navigation and control aspect. We began the design process by interviewing our client, Dr. Potter, and analyzing the user needs he gave us. We then came up with a variety of potential designs for the device, and weighed the pros and cons of each concept, selecting the best possible option. Three prototype performance goals were developed: the prototype can travel a certain distance with various terrain, the prototype can resist impact in a drop test, and the prototype can release the parachute and drive away following the drop. We then went through several iterations of the design, considering engineering models and running a series of tests designed to ensure that the device can fall from the rocket and navigate through desert terrain. These tests included surviving a drop of at least three stories, being able to release the parachute, and then drive away without us needing to modify anything on the device. Tests also examined the ability of our device to traverse gravel and sand over several kilometers on a single battery charge. Our final design succeeded in all three performance goals

Association between disruption of CD4 receptor dimerization and increased human immunodeficiency virus type 1 entry

BACKGROUND: Human immunodeficiency virus (HIV) enters target cells by a membrane fusion process that involves a series of sequential interactions between its envelope glycoproteins, the CD4 receptor and CXCR4/CCR5 coreceptors. CD4 molecules are expressed at the cell surface of lymphocytes and monocytes mainly as monomers, but basal levels of CD4 dimers are also present at the cell surface of these cells. Previous evidence indicates that the membrane distal and proximal extracellular domains of CD4, respectively D1 and D4, are involved in receptor dimerization. RESULTS: Here, we have used A201 cell lines expressing two CD4 mutants, CD4-E91K, E92K (D1 mutant) and CD4-Q344E (D4 mutant), harboring dimerization defects to analyze the role of CD4 dimerization in HIV-1 entry. Using entry assays based on β-lactamase-Vpr or luciferase reporter activities, as well as virus encoding envelope glycoproteins derived from primary or laboratory-adapted strains, we obtained evidence suggesting an association between disruption of CD4 dimerization and increased viral entry efficiency. CONCLUSION: Taken together, our results suggest that monomeric forms of CD4 are preferentially used by HIV-1 to gain entry into target cells, thus implying that the dimer/monomer ratio at the cell surface of HIV-1 target cells may modulate the efficiency of HIV-1 entry

Homelessness among older people: Assessing strategies and frameworks across Canada

Homelessness among older people is expected to rise as a result of unmet need and demographic change. Yet, strategies and responses to homelessness across Canada tend to focus on younger groups, overlooking the circumstances and needs of older people (i.e., age 50+). This article reports the results of a content analysis of government planning documents on homelessness conducted in 2014. A total of 42 local, provincial, and federal strategies were reviewed to assess the extent to which they recognized and targeted the needs of older people. Our review resulted in three categories of documents: 1) documents with no discussion of homelessness among older people (n=16; 38%); 2) documents with a minimal discussion of homelessness among older people (n=22; 55%); and 3) documents with a significant discussion of homelessness among older people (n=4; 7%). Results indicate that while many strategies are beginning to consider older people as a subgroup with unique needs, little action has been taken to develop comprehensive services and supports for this group. We conclude with a call to integrate the needs of diverse groups of older people into strategies to end homelessness and to develop programs and responses that are suitable for older people. L’itinérance parmi les personnes âgées: Évaluations des stratégies et des structures à travers le Canada RésuméIl est prévu que l’itinérance chez les personnes âgées augmentera au cours des prochaines années, en raison des changements démographiques et des besoins non comblés que l’on observe actuellement.  Malgré cela, les stratégies et les réponses à l’itinérance au Canada tendent à être centrées sur les populations plus jeunes, ignorant les besoins et réalités des personnes âgées. Cet article présente les résultats d’une analyse de contenu des stratégies canadiennes sur l’itinérance effectuée en 2014. 42 stratégies ont été recensées afin d’évaluer dans quelle mesure elles reconnaissaient et ciblaient les besoins des personnes âgées. Notre analyse regroupe en trois catégories les documents recensés : 1) les documents qui n’abordent pas l’itinérance chez les personnes âgées (n=16; 38 pour cent); 2) les documents  abordent très brièvement l’itinérance des personnes âgées (n=22; 55 pour cent); 3) les documents abordant de façon substantielle l’itinérance des personnes âgées (n=4; 7 pour cent). Les résultats indiquent que bien que plusieurs stratégies commencent à prendre en considération le fait que les personnes âgées constituent un sous-groupe qui présente des besoins particuliers, peu d’actions ont été entreprises afin de  développer des services et un soutien adaptés à leur réalité. Nous concluons en rappelant l’importance d’intégrer les besoins de différents groupes de personnes âgées aux stratégies qui visent à mettre fin à  l’itinérance et de développer des programmes et réponses qui sont adaptées à une population âgée. Mots Clefs : politique; pratique; vieillissement; exclusion sociale; pauvreté; logemen

Detection of genes influencing economic traits in three French dairy cattle breeds

A project of QTL detection was carried out in the French Holstein, Normande, and Montbéliarde dairy cattle breeds. This granddaughter design included 1 548 artificial insemination bulls distributed in 14 sire families and evaluated after a progeny-test for 24 traits (production, milk composition, persistency, type, fertility, mastitis resistance, and milking ease). These bulls were also genotyped for 169 genetic markers, mostly microsatellites. The QTL were analysed by within-sire linear regression of daughter yield deviations or deregressed proofs on the probability that the son receives one or the other paternal QTL allele, given the marker information. QTL were detected for all traits, including those with a low heritability. One hundred and twenty QTL with a chromosome-wise significance lower than 3% were tabulated. This threshold corresponded to a 15% false discovery rate. Amongst them, 32 were genome-wise significant. Estimates of their contribution to genetic variance ranged from 6 to 40%. Most substitution effects ranged from 0.6 to 1.0 genetic standard deviation. For a given QTL, only 1 to 5 families out of 14 were informative. The confidence intervals of the QTL locations were large and always greater than 20 cM. This experiment confirmed several already published QTL but most of them were original, particularly for non-production traits

Human T cell response to CD1a and contact dermatitis allergens in botanical extracts and commercial skin care products

During industrialization, humans have been exposed to increasing numbers of foreign chemicals. Failure of the immune system to tolerate drugs, cosmetics, and other skin products causes allergic contact dermatitis, a T cell–mediated disease with rising prevalence. Models of αβ T cell response emphasize T cell receptor (TCR) contact with peptide-MHC complexes, but this model cannot readily explain activation by most contact dermatitis allergens, which are nonpeptidic molecules. We tested whether CD1a, an abundant MHC I–like protein in human skin, mediates contact allergen recognition. Using CD1a-autoreactive human αβ T cell clones to screen clinically important allergens present in skin patch testing kits, we identified responses to balsam of Peru, a tree oil widely used in cosmetics and toothpaste. Additional purification identified benzyl benzoate and benzyl cinnamate as antigenic compounds within balsam of Peru. Screening of structurally related compounds revealed additional stimulants of CD1a-restricted T cells, including farnesol and coenzyme Q2. Certain general chemical features controlled response: small size, extreme hydrophobicity, and chemical constraint from rings and unsaturations. Unlike lipid antigens that protrude to form epitopes and contact TCRs, the small size of farnesol allows sequestration deeply within CD1a, where it displaces self-lipids and unmasks the CD1a surface. These studies identify molecular connections between CD1a and hypersensitivity to consumer products, defining a mechanism that could plausibly explain the many known T cell responses to oily substances

The Habitable Exoplanet Observatory (HabEx) Mission Concept Study Final Report

The Habitable Exoplanet Observatory, or HabEx, has been designed to be the Great Observatory of the 2030s. For the first time in human history, technologies have matured sufficiently to enable an affordable space-based telescope mission capable of discovering and characterizing Earthlike planets orbiting nearby bright sunlike stars in order to search for signs of habitability and biosignatures. Such a mission can also be equipped with instrumentation that will enable broad and exciting general astrophysics and planetary science not possible from current or planned facilities. HabEx is a space telescope with unique imaging and multi-object spectroscopic capabilities at wavelengths ranging from ultraviolet (UV) to near-IR. These capabilities allow for a broad suite of compelling science that cuts across the entire NASA astrophysics portfolio. HabEx has three primary science goals: (1) Seek out nearby worlds and explore their habitability; (2) Map out nearby planetary systems and understand the diversity of the worlds they contain; (3) Enable new explorations of astrophysical systems from our own solar system to external galaxies by extending our reach in the UV through near-IR. This Great Observatory science will be selected through a competed GO program, and will account for about 50% of the HabEx primary mission. The preferred HabEx architecture is a 4m, monolithic, off-axis telescope that is diffraction-limited at 0.4 microns and is in an L2 orbit. HabEx employs two starlight suppression systems: a coronagraph and a starshade, each with their own dedicated instrument

The Habitable Exoplanet Observatory (HabEx) Mission Concept Study Final Report

The Habitable Exoplanet Observatory, or HabEx, has been designed to be the Great Observatory of the 2030s. For the first time in human history, technologies have matured sufficiently to enable an affordable space-based telescope mission capable of discovering and characterizing Earthlike planets orbiting nearby bright sunlike stars in order to search for signs of habitability and biosignatures. Such a mission can also be equipped with instrumentation that will enable broad and exciting general astrophysics and planetary science not possible from current or planned facilities. HabEx is a space telescope with unique imaging and multi-object spectroscopic capabilities at wavelengths ranging from ultraviolet (UV) to near-IR. These capabilities allow for a broad suite of compelling science that cuts across the entire NASA astrophysics portfolio. HabEx has three primary science goals: (1) Seek out nearby worlds and explore their habitability; (2) Map out nearby planetary systems and understand the diversity of the worlds they contain; (3) Enable new explorations of astrophysical systems from our own solar system to external galaxies by extending our reach in the UV through near-IR. This Great Observatory science will be selected through a competed GO program, and will account for about 50% of the HabEx primary mission. The preferred HabEx architecture is a 4m, monolithic, off-axis telescope that is diffraction-limited at 0.4 microns and is in an L2 orbit. HabEx employs two starlight suppression systems: a coronagraph and a starshade, each with their own dedicated instrument.Comment: Full report: 498 pages. Executive Summary: 14 pages. More information about HabEx can be found here: https://www.jpl.nasa.gov/habex

Evaluating the Effects of SARS-CoV-2 Spike Mutation D614G on Transmissibility and Pathogenicity.

Global dispersal and increasing frequency of the SARS-CoV-2 spike protein variant D614G are suggestive of a selective advantage but may also be due to a random founder effect. We investigate the hypothesis for positive selection of spike D614G in the United Kingdom using more than 25,000 whole genome SARS-CoV-2 sequences. Despite the availability of a large dataset, well represented by both spike 614 variants, not all approaches showed a conclusive signal of positive selection. Population genetic analysis indicates that 614G increases in frequency relative to 614D in a manner consistent with a selective advantage. We do not find any indication that patients infected with the spike 614G variant have higher COVID-19 mortality or clinical severity, but 614G is associated with higher viral load and younger age of patients. Significant differences in growth and size of 614G phylogenetic clusters indicate a need for continued study of this variant