DeepFactors: Real-time probabilistic dense monocular SLAM

The ability to estimate rich geometry and camera motion from monocular imagery is fundamental to future interactive robotics and augmented reality applications. Different approaches have been proposed that vary in scene geometry representation (sparse landmarks, dense maps), the consistency metric used for optimising the multi-view problem, and the use of learned priors. We present a SLAM system that unifies these methods in a probabilistic framework while still maintaining real-time performance. This is achieved through the use of a learned compact depth map representation and reformulating three different types of errors: photometric, reprojection and geometric, which we make use of within standard factor graph software. We evaluate our system on trajectory estimation and depth reconstruction on real-world sequences and present various examples of estimated dense geometry

Post-Impact Thermal Evolution of Porous Planetesimals

Impacts between planetesimals have largely been ruled out as a heat source in the early Solar System, by calculations that show them to be an inefficient heat source and unlikely to cause global heating. However, the long-term, localized thermal effects of impacts on planetesimals have never been fully quantified. Here, we simulate a range of impact scenarios between planetesimals to determine the post-impact thermal histories of the parent bodies, and hence the importance of impact heating in the thermal evolution of planetesimals. We find on a local scale that heating material to petrologic type 6 is achievable for a range of impact velocities and initial porosities, and impact melting is possible in porous material at a velocity of > 4 km/s. Burial of heated impactor material beneath the impact crater is common, insulating that material and allowing the parent body to retain the heat for extended periods (~ millions of years). Cooling rates at 773 K are typically 1 - 1000 K/Ma, matching a wide range of measurements of metallographic cooling rates from chondritic materials. While the heating presented here is localized to the impact site, multiple impacts over the lifetime of a parent body are likely to have occurred. Moreover, as most meteorite samples are on the centimeter to meter scale, the localized effects of impact heating cannot be ignored.Comment: 38 pages, 9 figures, Revised for Geochimica et Cosmochimica Acta (Sorry, they do not accept LaTeX

An investigation into the factors involved in acclimatization to temperature and death at high temperature in calliphora erythrocephala (meig)

The heat resistance of Calliphora erythrocephala varies during the life history. The egg is most sensitive to high temperature and the puparium most resistant. Puparial resistance develops in the larval stage and declines in the young adult. This adult decline is temperature dependent and seems to be related to changes taking place during maturation. Evidence for the existence of development acclimatization was found to be contradictory, however, physiological acclimatization did occur in the adult. This latter form of acclimatization differs from the typical pattern observed with other species, for the increase in heat resistance with increasing temperature of acclimatization is not proportionate and it declines with adult age. The interaction of these factors makes resistance adaptation in Calliphora erythrocephala a complex phenomena. It is concluded that the primary lesion of heat death in adults is the uncoupling of the sarcosomal enzymes associated with oxidative phosphorylation of ɤ glycerophosphate. The heat sensitivity of this enzyme pathway is correlated with the heat death point of the whole animal and death is probably the result of a breakdown in ATF synthesis, which leads to the interruption of other energy dependent processes. The biochemical lesions during heat death are correlated with dramatic changes in the ultrastructure of sarcosomal cristae, which house the respiratory assemblies. This suggests that the structural and functional integrity of membrane-enzyme complexes are important factors in cellular metabolism. Studies on isolated sarcosomes have shown that the coupling of oxidative phosphorylation is influenced by both age and acclimatized state of the fly. The coupling enzymes are implicated in both the age dependent changes in heat resistance and also capacity adaptation. They are likely to be key factors in the temperature physiology of adult Calliphora

The Continuity Mindset for Christian Mission

Missionaries from the Global North regularly serve as trainers for Christians in the Global South. From personal experience, missionaries are regularly seen as being qualified to do this work simply because of their position. Rather than missionaries assuming they are competent purely on the basis of their titles, I believe they should instead practice the Continuity Mindset for Christian Mission, a mindset that emphasizes the continuity of one’s identity and ministry in one’s home culture with one’s identity and ministry in the host culture. This practice includes elements of vulnerable mission, nonresidential mission, tentmaking, cultural intelligence, and authentic leadership. I propose that the intentional practice of the continuity mindset can help missionaries from the Global North appropriately fulfill training responsibilities or ambitions they may have in the Global South. This article introduces the continuity mindset and how its theoretical foundations can aid missionaries from the Global North in laying down their power in order to better serve those to whom they are sent in the Global South

Following microscopic motion in a two dimensional glass-forming binary fluid

The dynamics of a binary mixture of large and small discs are studied at temperatures approaching the glass transition using an analysis based on the topology of the Voronoi polygon surrounding each atom. At higher temperatures we find that dynamics is dominated by fluid-like motion that involves particles entering and exiting the nearest-neighbour shells of nearby particles. As the temperature is lowered, the rate of topological moves decreases and motion becomes localised to regions of mixed pentagons and heptagons. In addition we find that in the low temperature state particles may translate significant distances without undergoing changes in their nearest neig hbour shell. These results have implications for dynamical heterogeneities in glass forming liquids.Comment: 12 pages, 7 figure

The peptide motif of the single dominantly expressed class I molecule of the chicken MHC can explain the response to a molecular defined vaccine of infectious bursal disease virus (IBDV)

In contrast to typical mammals, the chicken MHC (the BF-BL region of the B locus) has strong genetic associations with resistance and susceptibility to infectious pathogens as well as responses to vaccines. We have shown that the chicken MHC encodes a single dominantly expressed class I molecule whose peptide-binding motifs can determine resistance to viral pathogens, such as Rous sarcoma virus and Marek’s disease virus. In this report, we examine the response to a molecular defined vaccine, fp-IBD1, which consists of a fowlpox virus vector carrying the VP2 gene of infectious bursal disease virus (IBDV) fused with ?-galactosidase. We vaccinated parental lines and two backcross families with fp-IBD1, challenged with the virulent IBDV strain F52/70, and measured damage to the bursa. We found that the MHC haplotype B15 from line 15I confers no protection, whereas B2 from line 61 and B12 from line C determine protection, although another locus from line 61 was also important. Using our peptide motifs, we found that many more peptides from VP2 were predicted to bind to the dominantly expressed class I molecule BF2*1201 than BF2*1501. Moreover, most of the peptides predicted to bind BF2*1201 did in fact bind, while none bound BF2*1501. Using peptide vaccination, we identified one B12 peptide that conferred protection to challenge, as assessed by bursal damage and viremia. Thus, we show the strong genetic association of the chicken MHC to a T cell vaccine can be explained by peptide presentation by the single dominantly expressed class I molecule