The technical challenges of the Large Hadron Collider
The Large Hadron Collider (LHC) is a 27 km circumference hadron collider, built at CERN to explore the energy frontier of particle physics. Approved in 1994, it was commissioned and began operation for data taking in 2009. The design and construction of the LHC presented many design, engineering and logistical challenges which involved pushing a number of technologies well beyond their level at the time. Since the start-up of the machine, there has been a very successful 3-year run with an impressive amount of data delivered to the LHC experiments. With an increasingly large stored energy in the beam, the operation of the machine itself presented many challenges and some of these will be discussed. Finally, the planning for the next 20 years has been outlined with progressive upgrades of the machine, first to nominal energy, then to progressively higher collision rates. At each stage the technical challenges are illustrated with a few examples.
Challenges and Potential Solutions to Develop and Fund NASA Flagship Missions
Large, strategic “Flagship” missions have unique characteristics that lead to challenging developmental difficulties for the National Aeronautics and Space Administration (NASA). Missions such as the Hubble Space Telescope (HST), James Webb Space Telescope (JWST), and the Mars Science Laboratory (MSL) had technical and programmatic challenges that led to significant schedule delays and subsequent cost growth. Although NASA has instituted policies that have reduced cost growth for more “typical” NASA science missions, NASA Flagship missions remain a distinct challenge due to their requirement to provide unprecedented science or tackle bold exploration goals, typically while concurrently developing new technologies. The unique challenges presented by Flagship missions make it extremely difficult to fully predict cost and schedule given that the technical and programmatic advances needed to meet performance requirements are unprecedented. This paper addresses why Flagship missions are unique and proposes a new programmatic approach to develop and fund Flagship missions.
Target of inhibition by the anti-lipogenic antibiotic cerulenin of sterol synthesis in yeast.
Abstract The antibiotic cerulenin inhibited the incorporation of 14 C-acetyl-CoA by 67% at a concentration of 9 × 10 −6 M but not that of 14 C-HMG-CoA into the non-saponifiable fraction in a cell-free extract of Saccharomyces cerevisiae . Cerulenin markedly inhibited the activity of partially purified HMG-CoA synthase. No inhibition of acetoacetyl-CoA thiolase activity was observed in the same preparation of HMG-CoA synthase. Therefore, cerulenin inhibition of overall sterol synthesis may be accounted for by the specific inhibition of HMG-CoA synthase activity.