7 research outputs found
Toward a 21st-century health care system: Recommendations for health care reform
The coverage, cost, and quality problems of the U.S. health care system are evident. Sustainable health care reform must go beyond financing expanded access to care to substantially changing the organization and delivery of care. The FRESH-Thinking Project (www.fresh-thinking.org) held a series of workshops during which physicians, health policy experts, health insurance executives, business leaders, hospital administrators, economists, and others who represent diverse perspectives came together. This group agreed that the following 8 recommendations are fundamental to successful reform: 1. Replace the current fee-for-service payment system with a payment system that encourages and rewards innovation in the efficient delivery of quality care. The new payment system should invest in the development of outcome measures to guide payment. 2. Establish a securely funded, independent agency to sponsor and evaluate research on the comparative effectiveness of drugs, devices, and other medical interventions. 3. Simplify and rationalize federal and state laws and regulations to facilitate organizational innovation, support care coordination, and streamline financial and administrative functions. 4. Develop a health information technology infrastructure with national standards of interoperability to promote data exchange. 5. Create a national health database with the participation of all payers, delivery systems, and others who own health care data. Agree on methods to make de-identified information from this database on clinical interventions, patient outcomes, and costs available to researchers. 6. Identify revenue sources, including a cap on the tax exclusion of employer-based health insurance, to subsidize health care coverage with the goal of insuring all Americans. 7. Create state or regional insurance exchanges to pool risk, so that Americans without access to employer-based or other group insurance could obtain a standard benefits package through these exchanges. Employers should also be allowed to participate in these exchanges for their employees' coverage. 8. Create a health coverage board with broad stakeholder representation to determine and periodically update the affordable standard benefit package available through state or regional insurance exchanges
Genetic Engineering and Nitrogen Fixation
Nitrogen is extremely important in agriculture because it is a constituent of proteins, nucleic acids and other essential molecules in all organisms. Most of this nitrogen is derived from reduced or oxidized forms of N in the soil by growing plants, because plants and animals are unable to utilize N2, which is abundant in the atmosphere. Under most cropping conditions N is limiting for growth and is provided in fertilizers, usually at rates of between 50 and 300 kg of N per ha per year (Anonymous, 1979). The only other sources available to plants are from decomposing organic matter, soil reserves, biological nitrogen fixation, the little that is deposited in rainfall and from other sources such as automobile exhausts.
Biological nitrogen fixation, the enzymic conversion of N2 gas to ammonia, is much the most important source of fixed nitrogen entering those soils which receive less than about 5 kg N per ha per year from fertilizers. The reduction of N2 is catalysed by the nitrogenase system, which is very similar in composition and function in all prokaryotes which produce it Indeed, subunits of nitrogenase obtained from different nitrogen-fixing species can often be mixed to produce a functional system (Emerich and Burris, 1978). In addition, DNA coding for the structural proteins is so highly conserved in sequence that this coding has been used in hybridization experiments to demonstrate the presence of these genes in all nitrogen-fixing species of prokaryotes tested (Mazur, Rice and Haselkorn, 1980; Ruvkun and Ausubel, 1980). Nitrogenase is found only in prokaryotic micro-organisms and thus eukaryotes, such as plants!» can benefit from N2 fixation only jf they interact with N2-fixing species of micro-organism or obtain the fixed N after the death of the organisms.
Nitrogenase functions only under anaerobic conditions because it is irreversibly inactivated by oxygen. The fixation ofN2 requires large amounts of energy, about 30 moles of ATP per mole N2 reduced (Hill, 1976; Schubert and Wolk, 1982), and thus can act as a major drain for energy produced by N2-fixing micro-organisnls. The requirement for an anaerobic environment and large amounts of energy presents problems to the micro-organisms that fix N2 and to the geneticists who wish to extend the range of N2..fixing organisms. Many micro..organisms fix N2 anaerobically and thus avoid the oxygen problem. However, energy production from organic compounds is usually much more efficient when they are metabolized by oxidative phosphorylation. Thus, in general, nitrogen fixation under aerobic or microaerobic conditions should be more efficient, unless too much energy is lost in protecting the enzyme from oxygen or replacing oxygen-damaged proteins.
An important consequence of the large energy cost for biological nitrogen fixation is that the activity of nitrogenase needs to be regulated very carefully to ensure that only the required amount of fixed N is produced. We discuss the regulation of N2 fixation in Klebsiella pneumoniae in some detail in this chapter because a full understanding of how nitrogenase is regulated will be necessary if the transfer of N 2 fixation genes (nij') into other species, or even plants, is to be beneficial to the recipient organism.
The preceding remarks about the energy requirement and oxygen stability of nitrogenase point to two of the most important problems that will be faced in transferring nij"genes to new hosts. In this review we will discuss other potential problems and show how our knowledge of the genetics of nitrogen fixation might be exploited in future
Shock wave physics and detonation physics – a stimulus for the emergence of numerous new branches in science and engineering
In the period of the Cold War (1945−1991), Shock Wave Physics and Detonation Physics
(SWP&DP) – until the beginning of WWII mostly confined to gas dynamics, high-speed
aerodynamics, and military technology (such as aero- and terminal ballistics, armor
construction, chemical explosions, supersonic gun, and other firearms developments) –
quickly developed into a large interdisciplinary field by its own. This rapid expansion
was driven by an enormous financial support and two efficient feedbacks: the
Terminal Ballistic Cycle and the Research &
Development Cycle. Basic knowledge in SWP&DP, initially gained
in the Classic Period (from 1808) and further extended in the
Post-Classic Period (from the 1930s to present), is now increasingly
used also in other branches of Science and Engineering (S&E). However, also
independent S&E branches developed, based upon the fundamentals of SWP&DP,
many of those developments will be addressed (see Tab. 2). Thus, shock wave and detonation
phenomena are now studied within an enormous range of dimensions, covering microscopic,
macroscopic, and cosmic dimensions as well as enormous time spans ranging from
nano-/picosecond shock durations (such as produced by ultra-short laser pulses) to shock
durations that continue for centuries (such as blast waves emitted from ancient supernova
explosions). This paper reviews these developments from a historical perspective