The progenitors of calcium-rich transients are not formed in situ

We present deep VLT and HST observations of the nearest examples of calcium-rich 'gap' transients -- rapidly evolving transient events, with a luminosity intermediate between novae and supernovae. These sources are frequently found at large galactocentric offsets, and their progenitors remain mysterious. Our observations find no convincing underlying quiescent sources coincident with the locations of these transients, allowing us to rule out a number of potential progenitor systems. The presence of surviving massive-star binary companions (or other cluster members) are ruled out, providing an independent rejection of a massive star origin for these events. Dwarf satellite galaxies are disfavoured unless one invokes as yet unknown conditions that would be extremely favourable for their production in the lowest mass systems. Our limits also probe the majority of the globular cluster luminosity function, ruling out the presence of an underlying globular cluster population at high significance, and thus the possibility that they are created via dynamical interactions in dense globular cluster cores. Given the lack of underlying systems, previous progenitor suggestions have difficulty reproducing the remote locations of these transients, even when considering solely halo-borne progenitors. Our preferred scenario is that calcium-rich transients are high velocity, kicked systems, exploding at large distances from their natal site. Coupled with a long-lived progenitor system post-kick, this naturally explains the lack of association these transients have with their host stellar light, and the extreme host-offsets exhibited. Neutron star -- white dwarf mergers may be a promising progenitor system in this scenario.Comment: Accepted for publication in MNRAS, 11 pages, 9 figure

Kosmo's Farewell Advice

Joe Kosmo shared some final words and advice for his teammates in the Spacesuit and Crew Survival Systems Branch (EC5) and the Crew and Thermal Systems Division (CTSD (EC)) upon his retirement. He knew nothing about spacesuits when he started working for NASA in 1961, but neither did anyone else. He summed up the best lessons learned during his 50 years of developing U.S. spacesuits and encouraged the next generation s space industry workers to challenge what they hear and decide what is right. Topics include and oral history of early NASA manned flights by Richard S. Johnston, U.S. human spaceflight chronology, a history of advanced EVA project funding, and a discussion of NASA's innovative spirit

C60 adsorption on an aperiodically modulated Cu surface

Copper deposited on the ve-fold surface of icosahedral Al-Pd-Mn forms domains of a structure whose surface has a one-dimensional aperiodic modulation. It is shown that C60 deposited on this aperiodic film has highly reduced mobility as compared to C60 deposited on periodic Cu surfaces. This fnding is explained in terms of the recently proposed structural model of this system

Forces on Temperature Cables in a Model Bin Under Restrained Conditions

Temperature cables restrained from lateral movement, were measured as a function of grain height, cable location and surface coating. For the restrained conditions, the cable forces were one to nine times those previously measured for unrestrained cables. The large load increase on the restrained cables is believed to be caused by the flow profile which existed at each of the three different cable locations. The flow profile at the center cable is predominantly vertical and the forces in the restrained condition resembled those in the unrestrained condition. For the two outer cable locations, both vertical and lateral force components exist because of the nature of the discharging grain at these two different locations. For the restrained condition, the largest forces occurred on the cable located at the middle position. For the unrestrained condition, the largest forces occurred on the cable located at the wall position. Surface coatings on the cable had an effect on the magnitude of the forces. Forces on vinyl coated cables were significantly larger than either the nylon or HDLE polyethylene coated cables in the restrained condition

Shared responsibility: conceptualising how a public health approach may enhance police response to missing persons

When a person is reported missing there are substantial costs for the individual, their family and society. This paper conceptualises the experience of missing persons episodes, through a public health approach. This then allows police, stakeholders and the community to engage in discussions about who is vulnerable to going missing by intervening in a way that addresses risk. Historically, a missing persons episode involves an absence, typically followed by police involvement in consultation with next of kin with establishing the whereabouts of the missing person being the primary focus. Yet, the risk factors of going missing relate more to the psychosocial aspects that trigger a disappearance – family disconnection, mental health, poverty, intergenerational trauma. A narrative review of the literature reflects that the police are public health interventionists regarding social issues; however, this concept is untested in a missing persons context. Successful examples of public health approaches in the injury and violence prevention fields demonstrate that a public health approach is critical to address risk and protective factors. In a context of going missing (and the aftermath of a missing episode), enhanced awareness of the social and economic costs of an absence may prevent future episodes. This paper proposes a conceptual framework to address key challenges and risk factors in missing persons cases. The paper also proposes a future framework that emphasises shared responsibility between police working alongside public health and social care agencies to better support those at risk of going missing while fully engaging with the experiences of those who return

Today’s advanced is tomorrow’s basic

https://deepblue.lib.umich.edu/bitstream/2027.42/145431/1/13089_2018_Article_100.pd

Friction of Wheat: Grain-on-Grain and on Corrugated Steel

Coefficients of friction of wheat for grain–on–grain and on galvanized corrugated steel sheet were investigated using a modified direct shear apparatus. Tests were conducted under a normal pressure of 20.7 kPa using soft red winter wheat at a moisture content of 11.2% (w.b.) and an uncompressed bulk density of 740 kg/m3. Three consolidation procedures and three methods of deposition of grain in the test chamber were used. Test results of grain–on–grain friction showed that consolidation procedure markedly influenced the force–displacement relationship, while its influence on the coefficients of friction were small. Shearing to peak strength as a consolidation method erased all effects of loading history and resulted in the highest values of the coefficient of friction. Grain–on–grain coefficients of friction were in a range from 0.47 ± 0.007 to 0.56 ± 0.004 depending on the method of grain deposition. Friction on two dimensionally different samples of corrugated steel sheet was examined using three methods of grain deposition. Corrugation depths were 13 mm on both samples, while their periods were 67.5 mm (short) and 104 mm (long). Coefficients of friction on the short–period corrugated samples were in a range from 0.42 ± 0.0 to 0.46 ± 0.004 and were significantly higher (α = 5%) than those on the long–period corrugated sample, which ranged from 0.36 ± 0.003 to 0.39 ± 0.003. The method of grain deposition significantly (α = 5%) influenced the coefficients of friction of wheat on both types of corrugated steel sheet