Modification of amino acids at shock pressures of 3 to 30 GPA: Initial results

Since the discovery of amino acids in the Murchison meteorite, much speculation has focused on their origin and subsequent alteration, including the possible role of secondary processes, both terrestrial and extraterrestrial. As collisional processes and associated shock waves seem to have affected the silicate portions of many primitive meteorites, a mixture of powdered Allende (125-150 m grain size) and nine synthetic amino acids (six protein and three nonprotein) were subjected to controlled shock pressures from 3 to 30 GPa to determine the effect of shocks on amino acid survivability. Preliminary characterizations of the recovered shock products are presented

Preliminary analysis of LDEF instrument A0187-1: Chemistry of Micrometeoroids Experiment

The Chemistry of Micrometeoroids Experiment (CME) exposed approximately 0.8 sq. m of gold on the Long Duration Exposure Facility's (LDEF's) trailing edge (location A03) and approximately 1.1 sq. m of aluminum in the forward-facing A11 location. The most significant results to date relate to the discovery of unmelted pyroxene and olivine fragments associated with natural cosmic dust impacts. The latter are sufficiently large for detailed phase studies, and they serve to demonstrate that recovery of unmelted dust fragments is a realistic prospect for further dust experiments that will employ more advanced collector media. We also discovered that man-made debris impacts occur on the LDEF's trailing edge with substantially higher frequency than expected, suggesting that orbital debris in highly elliptical orbits may have been somewhat underestimated

Two Conceptions of Irreversible Environmental Harm

The concept of irreversibility plays a large role in the theory and practice of environmental protection. Indeed, the concept is explicit in some statements of the Precautionary Principle. But the idea of irreversibility remains poorly defined. Because time is linear, any loss is, in a sense, irreversible. On one approach, drawn from environmental economics, irreversibility might be understood as a reference to the value associated with taking precautionary steps that maintain flexibility for an uncertain future ( option value ). On another approach, drawn from environmental ethics, irreversibility might be understood to refer to the qualitatively distinctive nature of certain environmental harms—a point that raises a claim about incommensurability. The two conceptions fit different problems. For example, the idea of option value best fits the problem of climate change; the idea of qualitatively distinctive harms best fits the problem of extinction of endangered species. These ideas can be applied to a wide assortment of environmental problems

Delayed Interventions, Low Compliance, and Health Disparities Amplified the Early Spread of COVID-19

The United States (US) public health interventions were rigorous and rapid, yet failed to arrest the spread of the Coronavirus Disease 2019 (COVID-19) pandemic as infections spread throughout the US. Many factors have contributed to the spread of COVID-19, and the success of public health interventions depends on the level of community adherence to preventative measures. Public health professionals must also understand regional demographic variation in health disparities and determinants to target interventions more effectively. In this study, a systematic evaluation of three significant interventions employed in the US, and their effectiveness in slowing the early spread of COVID-19 was conducted. Next, community-level compliance with a state-level stay at home orders was assessed to determine COVID-19 spread behavior. Finally, health disparities that may have contributed to the disproportionate acceleration of early COVID-19 spread between certain counties were characterized. The contribution of these factors for the disproportionate spread of the disease was analyzed using both univariate and multivariate statistical analyses. Results of this investigation show that delayed implementation of public health interventions, a low level of compliance with the stay at home orders, in conjunction with health disparities, significantly contributed to the early spread of the COVID-19 pandemic