MISR stereoscopic image matchers: techniques and results

The Multi-angle Imaging SpectroRadiometer (MISR) instrument, launched in December 1999 on the NASA EOS Terra satellite, produces images in the red band at 275-m resolution, over a swath width of 360 km, for the nine camera angles 70.5/spl deg/, 60/spl deg/, 45.6/spl deg/, and 26.1/spl deg/ forward, nadir, and 26.1/spl deg/, 45.6/spl deg/, 60/spl deg/, and 70.5/spl deg/ aft. A set of accurate and fast algorithms was developed for automated stereo matching of cloud features to obtain cloud-top height and motion over the nominal six-year lifetime of the mission. Accuracy and speed requirements necessitated the use of a combination of area-based and feature-based stereo-matchers with only pixel-level acuity. Feature-based techniques are used for cloud motion retrieval with the off-nadir MISR camera views, and the motion is then used to provide a correction to the disparities used to measure cloud-top heights which are derived from the innermost three cameras. Intercomparison with a previously developed "superstereo" matcher shows that the results are very comparable in accuracy with much greater coverage and at ten times the speed. Intercomparison of feature-based and area-based techniques shows that the feature-based techniques are comparable in accuracy at a factor of eight times the speed. An assessment of the accuracy of the area-based matcher for cloud-free scenes demonstrates the accuracy and completeness of the stereo-matcher. This trade-off has resulted in the loss of a reliable quality metric to predict accuracy and a slightly high blunder rate. Examples are shown of the application of the MISR stereo-matchers on several difficult scenes which demonstrate the efficacy of the matching approach

Reducing the clique and chromatic number via edge contractions and vertex deletions.

We consider the following problem: can a certain graph parameter of some given graph G be reduced by at least d, for some integer d, via at most k graph operations from some specified set S, for some given integer k? As graph parameters we take the chromatic number and the clique number. We let the set S consist of either an edge contraction or a vertex deletion. As all these problems are NP-complete for general graphs even if d is fixed, we restrict the input graph G to some special graph class. We continue a line of research that considers these problems for subclasses of perfect graphs, but our main results are full classifications, from a computational complexity point of view, for graph classes characterized by forbidding a single induced connected subgraph H

SOXS: a wide band spectrograph to follow up transients

SOXS (Son Of X-Shooter) will be a spectrograph for the ESO NTT telescope capable to cover the optical and NIR bands, based on the heritage of the X-Shooter at the ESO-VLT. SOXS will be built and run by an international consortium, carrying out rapid and longer term Target of Opportunity requests on a variety of astronomical objects. SOXS will observe all kind of transient and variable sources from different surveys. These will be a mixture of fast alerts (e.g. gamma-ray bursts, gravitational waves, neutrino events), mid-term alerts (e.g. supernovae, X-ray transients), fixed time events (e.g. close-by passage of minor bodies). While the focus is on transients and variables, still there is a wide range of other astrophysical targets and science topics that will benefit from SOXS. The design foresees a spectrograph with a Resolution-Slit product ~ 4500, capable of simultaneously observing over the entire band the complete spectral range from the U- to the H-band. The limiting magnitude of R~20 (1 hr at S/N~10) is suited to study transients identified from on-going imaging surveys. Light imaging capabilities in the optical band (grizy) are also envisaged to allow for multi-band photometry of the faintest transients. This paper outlines the status of the project, now in Final Design Phase.Comment: 12 pages, 14 figures, to be published in SPIE Proceedings 1070

Home as a site of ontological security for people who have experienced homelessness: an exploration of community housing as a source of stability, control and safety

Housing is a key solution in addressing homelessness. Homelessness is a growing concern within Australia, and, for individuals who are experiencing homelessness, the unaffordability of rent in the private market can present significant challenges. The provision of affordable housing, in the form of community or public housing therefore becomes imperative - but community housing can take many potential forms, not all of which necessarily have the same impact on tenants. The current study investigates the different potential impacts of rooming houses and self-contained units to tease out some of these impacts. It draws on interview and participant observation data from an ethnographic case study that observed the SouthPort Community Housing Group Inc (SouthPort), a local housing provider in Victoria, Australia which provides housing to single people receiving government benefits. SouthPort manage 271 units for single people in the South Melbourne and Port Melbourne areas. However, at the time of research, SouthPort were still operating a rooming house, which does provide shelter and an alternative to rough sleeping, but which would still leave residents classified as homeless according to current understandings of homelessness. At the same time, even tenants who had never lived in SouthPort's own rooming house often had experience of earlier stays in rooming houses offered by other providers. The observational ad interview data therefore allowed for a comparison of tenants' lived experiences and evaluations of different forms of community housing. A key theoretical concept for this thesis is ontological security and, specifically, how a home acts as a site of ontological security. Traditionally, the literature on ontological security has been heavily focused on the role of home ownership. More recently, however, researchers have begun to examine the different and varying ways that people can experience home as a site of ontological security - including in contexts where the home is not, and can never be, a personal possession. This research has cast new light on the contributing factors of ontological security, and opens up the possible application of this concept to the study of homelessness. This study situates itself within this emerging scholarly subfield, and uses its case study to explore how community housing organisations can enable or hinder tenants' capacity to be ontologically secure - particularly through actions that best support tenants to remain in housing long term. The ethnographic observations and interviews that form the data for this case study were conducted over the course of a seven-month period at a single community housing organisation, located in inner Melbourne. Alongside observations, 26 semi-structured interviews were conducted with tenants, an ex-tenant, staff and a community housing worker. The results focus on three key areas - stability, control and safety - to understand whether and how tenants' homes serve as a site of ontological security, and to analyse whether there was a difference between rooming houses and self-contained units in supporting the development of ontological security. In brief, observational and interview data suggest that both rooming houses and self-contained unit could offer some measure of security of tenure to tenants, and thus provide some key elements of the stability needed for ontological security. Control, by contrast, varied substantially between rooming houses and self-contained units. Rooming house tenants were unable to exert control in their primary space, compared to tenants in a rooming house. The only space that rooming houses tenants had control was their bedroom, but bathroom and kitchen facilities required negotiation with their neighbours. This absence of control over personal and even intimate dimensions of tenants' lives, greatly hindered the ability of rooming houses to function as a site of ontological security. Self-contained units, however, generally provided the control needed for tenants¿ homes to function as a site of ontological security. Even in self-contained units, however, tenants' interviews suggested that control could still depend on neighbours and their actions in secondary spaces, qualifying the degree to which even self-contained units could satisfy this contributor to tenants' experience of ontological security. Safety was a concern for tenants in both rooming houses and self-contained units. Rooming houses were seen as unsafe by tenants - due particularly to the presence of drugs, violence and the need to share facilities. Tenants' perceptions of safety within self-contained units varied, with unsafe practices of neighbours again posing a perceived risk to the safety of others who had to live in the same complexes. These safety concerns qualify the extent to which tenants could rely on self-contained units to function as a site of ontological security. Given the diverse nature of tenants' experiences of home as a site of ontological security, this thesis concludes by suggesting that self-contained units have the capacity to function as a site of ontological security - with significant qualifications that underscore the importance of supporting tenants' control over, and safety within and around, their accommodation. Rooming houses on the other hand, were not seen to be able to function as a site of ontological security due to the lack of control and safety concerns raised during the research

Two different charge-separation pathways in photosystem II

Charge separation is an essential step in the conversion of solar energy into chemical energy in photosynthesis. To investigate this process, we performed transient absorption experiments at 77 K with various excitation conditions on the isolated Photosystem II reaction center preparations from spinach. The results have been analyzed by global and target analysis and demonstrate that at least two different excited states, (Ch

Elongation, rooting and acclimatization of micropropagated shoots from mature material of hybrid larch

Factors were defined for elongation, rooting and acclimatization of micropropagated shoots of Larix x eurolepis Henry initiated from short shoot buds of plagiotropic stecklings serially propagated for 9 years from an 8-year-old tree. Initiation and multiplication were on Schenk and Hildebrandt (SH) medium supplemented with 5 μM 6-benzyladenine (BA) and 1 μM indole-butyric acid (IBA). Stem elongation was obtained in 36% of the shoots on SH medium containing 0.5 μM BA and 63% of the remaining non-elongated shoots initiated stem elongation after transfer on SH medium devoid of growth regulators. Rooting involved 2 steps: root induction on Campbell and Durzan mineral salts and Murashige and Skoog organic elements, both half-strength (CD-MS/2), supplemented with 1 μM of both naphthaleneacetic acid (NAA) and IBA, and root elongation following transfer to CD-MS/2 medium devoid of growth regulators. Repeating this 2-step sequence yielded up to 67% rooted shoots. Acclimatization of plantlets ranged from 83% to 100%. Over 300 plants were transferred to the greenhouse; some showed plagiotropic growth

Meiotic silencing and fragmentation of the male germline restricted chromosome in zebra finch

During male meiotic prophase in mammals, X and Y are in a largely unsynapsed configuration, which is thought to trigger meiotic sex chromosome inactivation (MSCI). In avian species, females are ZW, and males ZZ. Although Z and W in chicken oocytes show complete, largely heterologous synapsis, they too undergo MSCI, albeit only transiently. The W chromosome is already inactive in early meiotic prophase, and inactive chromatin marks may spread on to the Z upon synapsis. Mammalian MSCI is considered as a specialised form of the general meiotic silencing mechanism, named meiotic silencing of unsynapsed chromatin (MSUC). Herein, we studied the avian form of MSUC, by analysing the behaviour of the peculiar germline restricted chromosome (GRC) that is present as a single copy in zebra finch spermatocytes. In the female germline, this chromosome is present in two copies, which normally synapse and recombine. In contrast, during male meiosis, the single GRC is always eliminated. We found that the GRC in the male germline is silenced from early leptotene onwards, similar to the W chromosome in avian oocytes. The GRC remains largely unsynapsed throughout meiotic prophase I, although patches of SYCP1 staining indicate that part of the GRC may self-synapse. In addition, the GRC is largely devoid of meiotic double strand breaks. We observed a lack of the inner centromere protein INCENP on the GRC and elimination of the GRC following metaphase I. Subsequently, the GRC forms a micronucleus in which the DNA is fragmented. We conclude that in contrast to MSUC in mammals, meiotic silencing of this single chromosome in the avian germline occurs prior to, and independent of DNA double strand breaks and chromosome pairing, hence we have named this phenomenon meiotic silencing prior to synapsis (MSPS)

Cyclic dinucleotides bind the C-linker of HCN4 to control channel cAMP responsiveness

cAMP mediates autonomic regulation of heart rate by means of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, which underlie the pacemaker current If. cAMP binding to the C-terminal cyclic nucleotide binding domain enhances HCN open probability through a conformational change that reaches the pore via the C-linker. Using structural and functional analysis, we identified a binding pocket in the C-linker of HCN4. Cyclic dinucleotides, an emerging class of second messengers in mammals, bind the C-linker pocket (CLP) and antagonize cAMP regulation of the channel. Accordingly, cyclic dinucleotides prevent cAMP regulation of If in sinoatrial node myocytes, reducing heart rate by 30%. Occupancy of the CLP hence constitutes an efficient mechanism to hinder β-adrenergic stimulation on If. Our results highlight the regulative role of the C-linker and identify a potential drug target in HCN4. Furthermore, these data extend the signaling scope of cyclic dinucleotides in mammals beyond their first reported role in innate immune system

Regulating STING in health and disease.

The presence of cytosolic double-stranded DNA molecules can trigger multiple innate immune signalling pathways which converge on the activation of an ER-resident innate immune adaptor named "STimulator of INterferon Genes (STING)". STING has been found to mediate type I interferon response downstream of cyclic dinucleotides and a number of DNA and RNA inducing signalling pathway. In addition to its physiological function, a rapidly increasing body of literature highlights the role for STING in human disease where variants of the STING proteins, as well as dysregulated STING signalling, have been implicated in a number of inflammatory diseases. This review will summarise the recent structural and functional findings of STING, and discuss how STING research has promoted the development of novel therapeutic approaches and experimental tools to improve treatment of tumour and autoimmune diseases