160,647 research outputs found
Arcus: the x-ray grating spectrometer explorer
No full textArcus will be proposed to the NASA Explorer program as a free-flying satellite mission that will enable high-resolution soft X-ray spectroscopy (8-50Å) with unprecedented sensitivity - effective areas of > 500 sq cm and spectral resolution > 2500. The Arcus key science goals are (1) to determine how baryons cycle in and out of galaxies by measuring the effects of structure formation imprinted upon the hot gas that is predicted to lie in extended halos around galaxies, groups, and clusters, (2) to determine how black holes influence their surroundings by tracing the propagation of out-flowing mass, energy and momentum from the vicinity of the black hole out to large scales and (3) to understand how accretion forms and evolves stars and circumstellar disks by observing hot infalling and outflowing gas in these systems. Arcus relies upon grazing-incidence silicon pore X-ray optics with the same 12m focal length (achieved using an extendable optical bench) that will be used for the ESA Athena mission. The focused X-rays from these optics will then be diffracted by high-efficiency off-plane reflection gratings that have already been demonstrated on sub-orbital rocket flights, imaging the results with flight-proven CCD detectors and electronics. The power and telemetry requirements on the spacecraft are modest. The majority of mission operations will not be complex, as most observations will be long (∼100 ksec), uninterrupted, and pre-planned, although there will be limited capabilities to observe targets of opportunity, such as tidal disruption events or supernovae with a 3-5 day turnaround. After the end of prime science, we plan to allow guest observations to maximize the science return of Arcus to the community
The Biology and Biochemistry of PhoH2 proteins
No full textPhoH2 proteins are found in a diverse range of organisms. To date little is known about these proteins and the role they play in the organisms in which they reside. PhoH2 is a PIN PhoH domain fusion, and these proteins are currently annotated as having unknown function and are described as PhoH like. PhoH domains are thought to be ATPases and all characterised PIN domain proteins are RNases. Most efforts have focussed on determining the role of PIN domain proteins that comprise the toxic component (VapC) of VapBC toxin antitoxin systems, in which the PIN domain is coexpressed as part of an operon with an inhibitor (VapB). In the remaining cases where PIN domain proteins can be found such as PIN PhoH domain fusions, these cases remain unexamined. This thesis describes the biological and biochemical characterisation of the PIN PhoH protein, PhoH2 from Mycobacterium tuberculosis and Mycobacterium smegmatis, along with a preliminary structural characterisation of a thermophilic PhoH2 protein homologue.
The phoH2 gene from both mycobacterial organisms was found to be expressed as part of a long mRNA transcript. Examination of these transcripts revealed possible alternative 5’ start sites out of frame with the phoH2 gene. For protein overexpression, and ‘normal’ growth and colony formation with conditional overexpression, phoH2 from M. tuberculosis required 152 bp of the 5’ sequence directly upstream of the annotated phoH2 gene (annotated here as phoH2alt). PhoH2 proteins: PhoH2alt MTB, PhoH2alt MSMEG and PhoH2MSMEG show ATP/Mg²⁺ dependent, sequence specific RNA unwinding and cleavage. The sequence (A C) (A/U) (A/U) (G/C) U was deduced as a substrate for PhoH2, and PhoH2alt MTB also demonstrated unwinding and cleavage activity on its upstream ~152 base RNA transcript, suggesting a potential autoregulatory mechanism. Structural analysis of a thermophilic PhoH2 protein homologue has provided preliminary crystallographic data which along with electron microscopy suggest a ring like hexameric PhoH2 oligomer
The Biochemistry of VapBC Toxin-Antitoxins
No full textThe VapBC toxin-antitoxin (TA) systems were first identified in 2005 and little is known about their contemporary biological function, despite the fact that VapBC TAs are the largest TA family and are widespread in bacteria and archaea (Arcus, Rainey, & Turner, 2005; Gerdes, Christensen, & Lobner-Olsen, 2005). Mycobacterium tuberculosis has a surprisingly large repertoire of 45 VapBC TAs. In contrast Mycobacterium smegmatis, a model organism for M. tuberculosis, contains only one vapBC operon, thereby making it an ideal system to uncover the possible role(s) that VapBC proteins play in mycobacteria. This thesis describes the functional characterisation of VapC from M. smegmatis and two homologues from Pyrobaculum aerophilum, along with biophysical characterisation of the VapBC complex from M. smegmatis. The VapBC proteins from M. smegmatis form a tight complex in a 1:1 ratio and interactions between the proteins result in a tetramer of VapBC heterodimers. VapB is susceptible to proteolytic degradation when not bound to DNA thus hinting at a mechanism for VapC activation.
VapC proteins from P. aerophilum (VapCPAE2754 and VapCPAE0151) and VapC from M. smegmatis display Mg²⁺/Mn²⁺ dependent, sequence specific ribonuclease activity. VapC from M. smegmatis targets the AU rich sequences AUAU and AUAA. Whereas VapCPAE2754 and VapCPAE0151 from P. aerophilum both target GGUG and GGGG sequences. These sequences are present in over half the mRNA transcripts encoded in the P. aerophilum genome, making them potent toxins. VapC ribonuclease activity is inhibited when VapC is bound to VapB. When VapC is released from the VapBC complex it cleaves cohorts of mRNA transcripts thereby reducing protein synthesis for this cohort of genes. Microarray analysis revealed that the majority of transcripts downregulated in response to VapC expression in M. smegmatis are involved in carbon utilisation and transport (Robson, 2010). Bioinformatics shows that the target sequence is overrepresented in the downregulated transcripts. The majority of the downregulated genes are in operons, which suggests a mechanism for destabilising mRNA transcripts to regulate specific metabolic processes
Arcus: the soft x-ray grating explorer
No full text© COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only. Arcus provides high-resolution soft X-ray spectroscopy in the 12-50 Å bandpass with unprecedented sensitivity, including spectral resolution < 2500 and effective area < 250 cm2. The three top science goals for Arcus are (1) to measure the effects of structure formation imprinted upon the hot baryons that are predicted to lie in extended halos around galaxies, (2) to trace the propagation of outflowing mass, energy, and momentum from the vicinity of the black hole to extragalactic scales as a measure of their feedback, and (3) to explore how stars form and evolve. Arcus uses the same 12 m focal length grazing-incidence Silicon Pore X-ray Optics (SPOs) that ESA has developed for the Athena mission; the focal length is achieved on orbit via an extendable optical bench. The focused X-rays from these optics are diffracted by high-efficiency Critical-Angle Transmission (CAT) gratings, and the results are imaged with flight-proven CCD detectors and electronics. Combined with the high-heritage NGIS LEOStar-2 spacecraft and launched into 4:1 lunar resonant orbit, Arcus provides high sensitivity and high efficiency observing of a wide range of astrophysical sources
Prof. Th. W. Adorno and the author Hans Erich Nossack.
No full textProf. Th. W. Adorno and the author Hans Erich Nossack at a reception of Insel Verlag, Buchmesse Frankfurt 1966LB
Nowe spojrzenie na planowanie architektury mieszkaniowej w afryce subsaharyjskiej
No full textThe author shares his reflections on state of art in housing and urban planning, deficiencies, expectations and possibilities in the Sahel region of Africa. He notices, that the housing problem in Africa is one of the challenges, which should be solved in order to recover life dignity of African people and secure their rights to traditional family life in acceptable conditions. The paper describes the studies on the typical dispersed urban structures and the need to foster this type of settlement structure and proposals of introduction of new on light steel frame housing system in the area of Sahel, combining the traditional way of building houses with modern technology. The particularly analysed case, is the housing problem in the Republic of Chad. The author presents the basic discussion on this topic and his architectural proposals. Unfortunately, the gap between the needs and the financial feasibility of housing construction in this area, makes this project already at the starting point extremely difficult to be realized without external subventions.Problem mieszkaniowy w Afryce jest jednym z wyzwań, które należy rozwiązać, aby Afrykanie mogli odzyskać godność życiową i zabezpieczyć swoje prawa do tradycyjnego życia rodzinnego w akceptowalnych warunkach. W artykule opisano badania nad typowymi rozproszonymi strukturami miejskimi i potrzebą wspierania tego typu struktur osadniczych oraz propozycji wprowadzenia nowego systemu konstrukcji domów, opartym na lekkim szkielecie stalowym, łączącym tradycyjny sposób budowania domów z nowoczesną technologią. Przypadkiem szczególnie analizowanym jest problem mieszkaniowy w Republice Czadu. Autor przedstawia podstawową dyskusję na ten temat i swoje propozycje architektoniczne. Niestety luka między potrzebami mieszkaniowymi w Czadzie a finansową wykonalnością budownictwa mieszkaniowego w tym obszarze sprawia, że projekt ten, już w punkcie wyjścia, jest niezwykle trudny do realizacji bez uzyskania zewnętrznych dotacji
Gridded temperature maximum for global photosynthesis, in NetCDF format
No full textTwo important points exist within temperature dependence curves for biosphere metabolism: the inflection point (T_inf), and the thermal maximum (T_max). The inflection point for temperature dependent rates represents temperatures where an increase in rate (k) is maximal relative to temperature (T). The thermal maximum represents the top of the temperature dependence curve where any additional increase in temperature will decrease metabolic rate. Here we define T_max for the land uptake as temperatures beyond which photosynthetic rate decreases (T_max).
T_max was calculated for the terrestrial biosphere using MacroMolecular Rate Theory(MMRT) and FLUXNET data. More information on MMRT can be found in Arcus et al. (2016).
Information on the 2015 FLUXNET synthesis dataset can be found here: fluxdata.or
Cassini RADAR images at hotei arcus and western Xanadu, Titan: Evidence for geologically recent cryovolcanic activity
No full textImages obtained by the Cassini Titan Radar Mapper (RADAR) reveal lobate, flowlike features in the Hotei Arcus region that embay and cover surrounding terrains and channels. We conclude that they are cryovolcanic lava flows younger than surrounding terrain, although we cannot reject the sedimentary alternative. Their appearance is grossly similar to another region in western Xanadu and unlike most of the other volcanic regions on Titan. Both regions correspond to those identified by Cassini's Visual and Infrared Mapping Spectrometer (VIMS) as having variable infrared brightness, strengthening the case that these are recent cryovolcanoes. Citation: Wall, S. D., et al. (2009), Cassini RADAR images at Hotei Arcus and western Xanadu, Titan: Evidence for geologically recent cryovolcanic activity, Geophys. Res. Lett., 36, L04203, doi: 10.1029/2008GL036415
Seeing the world anew : the radical vision of Martin Waldseemüller's 1507 & 1516 world maps /
No full text9781929154470 (ISBN). 192915447X (ISBN). First edition 2012. Accompanied by 2 foldeds map in front and back pockets: 1507 map -- 1516 map.; Includes bibliographical references: pages 98-107.; Maps from pockets also available online http://nla.gov.au/nla.map-vn6254227; Original version of the 1507 map: Universalis cosmographiae secundum Ptholomaei traditionem et Americi Vespucii alioru que lustrationes. [St. Dié, France? : s.n., 1507]; Original version of the 1516 map: Carta marina, navigatoria Portugallen, navigationes atque tocius cogniti orbis terre marisque formam naturamq[u]e situs et terminos nostris temporibus recognitos et ab antiquorum traditione differentes eciam quor[um] vetusti non meminerunt auctores hec generaliter indicat / consumatum est in oppido S. Deodati compositione et digestione Martini Waldseemuller Ilacomili. [St. Dié, France? : s.n., 1516]. Prologue: In a Renaissance Vision, a Glimpse of the Modern / John W. Hessler -- "An island surrounded on all sides by sea" : The World Map, 1507 / John W. Hessler -- "Land of Cuba, part of Asia" : The Carta marina, 1516 / Chet Van Duzer -- Epilogue: A Renaissance That Resonates Still / John W. Hessler -- Notes -- Afterword / Ralph E. Ehrenberg -- About the authors -- Acknowledgments -- The Maps: The 1507 World Map, 12 sheets, with commentary -- Composite: front pocket -- The 1516 Carta marina, 13 sheets, with commentary -- Composite: back pocket
Klimat społeczny w szkole inkluzyjnej
No full textAuthor presented in this paper theoretical approach to the building of social climate in an inclusive school. The publication indicatessome tendencies and directions of changes to improve the functioning of these institutions and to implement the idea of inclusive education.Autorka przedstawiła w artykule teoretyczne ujęcie zagadnienia związanego z budowaniem klimatu społecznego w szkole inkluzyjnej. W publikacji ukazano pewne dążenia i kierunki zmian, jakich należy dokonywać w masowych szkołach, aby poprawić jakość funkcjonowania tych placówek, tak by kierowały się one ideą edukacji włączającej
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