1996 - The Tree of Life Gets a New Branch
Classification schemes only work if everything fits in the scheme. For many years, biologists struggled because some single-celled organisms didn't fit with the known microbes called bacteria. This landmark paper described results of sequencing the genome of a heat-loving microbe Methanococcus jannaschii, originally isolated from vents on the ocean's floor. The genome sequencing results confirmed earlier ribosomal RNA-based classification schemes establishing Archaea as a distinct third branch of the Tree of Life. Prokaryotes are actually either Archaea or bacteria; the difference is in the genes. The genes and metabolic pathways in Archaea are sufficiently different from those found in bacteria and those found in complex, multi-celled organisms to warrant a separate classification. The paper was an important confirmation of the tripartite view of the Tree of Life.
C.J. Bult, et al., "Complete genome sequence of the methanogenic archaeon, Methanococcus jannaschii." Science 273, 1058-1073 (1996). [DOI: 10.1126/science.273.5278.1058]. Subscription required: contact your local librarian for access. (Image credit: Claire Ballweg, Department of Energy)
1996 - Message Passing Gets the Job Done on Supercomputers
In a most unusual case of writer's block, programmers could not commit to writing different versions of their codes if they could not move them from one machine to another. In the 1980's, computers used vendor-specific libraries, which let them write codes to take advantage of supercomputing's power. A group of computer scientists (many funded by DOE), computer vendors and the scientists who used the computers to solve tough problems worked together over several years to define the Message Passing Interface (MPI) standard, which created an interface between the code and the different libraries. This landmark 1996 paper described how MPICH, the first full implementation of the MPI standard, allowed programmers to develop software with confidence that it would run on both current and future supercomputers of every shape and size, including some of the world's fastest supercomputers. The software is freely available and both users and vendors have been quick to adopt it.
W. Gropp, E. Lusk, and A. Skjellum, "A high-performance, portable implementation of the MPI Message Passing Interface." Parallel Computing 22, 789-828 (1996). (Image credit: Claire Ballweg, Department of Energy)
1995 - Climbing to the Top of Quarks
Since the 1977 discovery of the bottom quark, an elementary particle, scientists had been hunting for its partner particle, the top quark, as predicted by the Standard Model. Published 18 years after the search began, these landmark 1995 papers described the discovery of the top quark, which alone is massive enough to fall just short of gold on the Periodic Table. The top quark was discovered by the CDF and D0 experiments at DOE's Fermilab Tevatron Collider in the high-energy collisions of protons and antiprotons. Since the discovery, both the Fermilab Tevatron Collider and CERN Large Hadron Collider programs have measured the top quark's properties with increasing precision to test the Standard Model.
F. Abe, et al. (CDF Collaboration), "Observation of top quark production in pp collisions with the collider detector at Fermi lab." Physical Review Letters 74, 2626 (1995). [DOI: 10.1103/PhysRevLett.74.26.26]. Subscription required: contact your local librarian for access.
S. Abachi, et al. (D0 Collaboration), "Observation of the top quark." Physical Review Letters 74, 2632 (1995). [DOI: 10.1103/PhysRevLett.74.2632]. Subscription required: contact your local librarian for access. (Image credit: Claire Ballweg, Department of Energy)
1994 - A Shift in the Likelihood of Fusion
A challenge with fueling a fusion reactor is reliably getting the fusion reaction to occur. In this landmark 1994 paper, scientists described a high-powered mixture of fusion fuels that allowed the Tokamak Fusion Test Reactor (TFTR) to shatter the world-record for fusion energy when it generated 6 million watts of power. This milestone was achieved using a 50/50 blend of two hydrogen isotopes: deuterium and tritium. The work was instrumental in building the scientific basis for ITER, a tokamak-based reactor to be fueled by deuterium and tritium and designed to test the viability of fusion as an energy source.
J.D. Strachan, et al., "Fusion power production from TFTR plasmas fueled with deuterium and tritium." Physical Review Letters 72, 3526 (1994). [DOI: 10.1103/PhysRevLett.72.3526]. Subscription required: contact your local librarian for access. (Image credit: Princeton Plasma Physics Laboratory)
1993 - Storing Data: From 1 Byte a Second to 1,000,000,000
In the 1990s, supercomputers stored information at the frustratingly slow rate of 1 to 10 million bytes a second. A byte is the space needed to store one character. Today, supercomputers can save a billion bytes a second – an innovation largely spurred by this landmark 1993 paper written by people at the DOE national labs and IBM. The paper described the High Performance Storage System (HPSS). The HPSS software coordinates among computers, hard disks and tape drives to store and manage access to extreme amounts of data. It can serve up data to multiple users simultaneously, reducing wait times involved in research and analysis. Further, the design of the software lets storage capacity and technology grow and change to meet the demands for increasingly detailed analysis on ever-larger supercomputers.
R.A. Coyne, H. Hulen, and R. Watson, "The High Performance Storage System." Supercomputing '93 Proceedings of the 1993 ACM/IEEE Conference on Supercomputing 83-92 (1993). [DOI: 10.1145/169627.169662]. The paper is available via a free web account on ACM Digital Library. (Image credit: Pacific Northwest National Laboratory)
1992 - The Big Bang Becomes a Household Phrase
While the Big Bang often discussed in science classes today was first theorized in the 1940s, it wasn't actually confirmed until later. This landmark 1992 paper presented the discovery and mapping of tiny temperature fluctuations in the cosmic microwave background by the NASA-led COBE mission, where DOE researchers led one of the primary instrument teams. These minuscule changes, tiny ripples in space-time fabric, were the seeds of stars and planets. The finding – which Stephen Hawking called the "discovery of the century, if not all time" – pushed the Big Bang into the common vocabulary and garnered the 2006 Nobel Prize in Physics.
G.F. Smoot, C.L. Bennett, A. Kogut, E.L. Wright, J. Aymon, N.W. Boggess, E.S. Cheng, S. Gulkis, and M.G. Hauser, "Structure in the COBE differential microwave radiometer first-year maps." The Astrophysical Journal 396, L1-L-5 (1992). [DOI: 10.1086/186504]. (Image credit: Berkeley Lab)
1990 - Smooth Sailing for Plasmas Solves Issues in Fusion Science
Creating conditions for nuclear fusion in the laboratory requires the calming of turbulence generated by scorching hot plasmas. Rapid spatial changes (known as shear) in the plasma density and temperature drive turbulent eddies that carry heat and particles outside of the plasma. In this landmark 1990 paper, Richard Groebner and his team at the DIII-D National Fusion Facility realized that turbulence could be interrupted by a sheared flow of plasma. The sheared flow reduces the size of turbulent eddies and allows the plasma to reach higher overall temperatures. This turbulence-reducing process is one that will allow the ITER tokamak to demonstrate net fusion power generation.
R.J. Groebner, K.H. Burrell, and R.P. Seraydarian, "Role of edge electric field and poloidal rotation in the L-H transition." Physical Review Letters 64, 3015 (1990). [DOI: 10.11.03/PhysRevLett.64.3015]. Subscription required: contact your local librarian for access. (Image credit: Solar Dynamics Observatory/NASA)
1990 - The Median on Light's Highway
Just as a highway median separates and controls traffic, materials that control light also use a median that researchers call a band gap. Scientists thought it would be easy to build orderly three-dimensional structures with glass-like spheres to create materials with band gaps. They built and tested numerous options, but sorting through the many permutations, such as the size of spheres, to find band gaps was like finding a needle in a very large haystack. This landmark 1990 paper took the problem off the laboratory bench by calculating the right arrangement of spheres to create a band gap. They found that to get a band gap they needed to put these spheres in a four-sided, tetrahedral structure, reminiscent of diamonds. A short time later, others verified that this structure controls light as calculated. The paper is cited as an early starting point in the creation of materials that can control light.
K.M. Ho, C.T. Chan, and C.M. Soukoulis, "Existence of a photonic gap in periodic dielectric structures." Physical Review Letters 65, 3152-3155 (1990). Subscription required: contact your local librarian for access. (Image credit: Ames Laboratory)
1989 - Measuring Plasma Current in a Tokamak
The fourth state of matter (a plasma, a hot ionizing gas) can be used to produce vast amounts of electricity, but first it must be controlled. In the 1950s, scientists used helical magnetic fields to bottle a plasma in a configuration known as a tokamak that insulated it from the surrounding walls. But they needed a way to discern how induced electrical currents in the plasma modify the magnetic field that guides the plasma and protects the surrounding walls. A landmark 1989 paper explained how to measure the magnetic field by interpreting visible light emitted by atoms injected into the plasma using accelerated hydrogen beams. Today, these measurements allow scientists to precisely tailor the magnetic field to improve plasma confinement and maximize fusion performance.
F.M. Levinton, R.J. Fonck, G.M. Gammel, R. Kaita, H.W. Kugel, E.T. Powell, and D.W. Roberts, "Magnetic field pitch-angle measurements in the PBX-M tokamak using the motional Stark effect." Physical Review Letters 63, 2060 (1989). [DOI: 10.1103/PhysRevLett.63.2060]. Subscription required: contact your local librarian for access. (Image credit: Claire Ballweg, DOE)
1989 - Details Where You Want Them
If you're modeling an airplane wing, you want to focus your supercomputer on the details that matter. That is, you want to efficiently obtain the details on the most interesting parts of the problem. The landmark 1989 paper described a solution to the problem: the adaptive mesh refinement (AMR). The AMR resulted in a much more detailed understanding of what was happening by focusing on the areas of interest. AMR is used worldwide and in a wide array of applications, from airplane engines to ice sheets.
M.J. Berger and P. Colella, "Local adaptive mesh refinement for shock hydrodynamics." Journal of Computational Physics 82(1), 64-84 (1989). [DOI: 10.1016/0021-9991(89)90035-1]. Contact your local librarian for access. (Image credit: Dan Martin, Lawrence Berkeley National Laboratory)
1989 - Acid Rain and the Nation
How the "acid" got into "acid rain" -- and snow, fog, hail and dust containing acidic components fell far from the source wasn't known until this 1989 landmark paper. Stephen Schwartz at DOE's Brookhaven National Laboratory identified the underlying causes, processes and impacts of this precipitation. He also explained how sulfur and nitrogen oxides released at one source caused acid rain in other environments. Schwartz's findings gave the first clear picture of the nationwide impacts of different sulfur and nitrogen sources and led to changes to the Clean Air Act.
S.E. Schwartz, "Acid deposition: Unraveling a regional phenomenon." Science 243, 753-763 (1989). [DOI: 10.1126/science.243.4892.753]. Subscription required: contact your local librarian for access. (Photo credit: public domain)
1988 - Teaching Protocol to Computers
In October 1986, the "information highway" had the first of what was to be a series of traffic jams. These crashes stopped people from retrieving email, accessing data or viewing websites. How could these collapses be avoided? This landmark 1988 paper described and analyzed five algorithms that shed light on the flow of data packets. In addition, the paper detailed how to tune the Berkeley Unix Transmission Control Protocol, which enabled systems to connect and exchange data streams under abysmal network conditions. This paper laid out the foundations for controlling and avoiding congestion in the Internet.
V. Jacobson, "Congestion avoidance and control." ACM SIGCOMM'88 18(4), 314-319 (1988). [DOI: 10.1145/52325.52356]. The paper is available via a free web account on ACM Digital Library. (Image credit: Claire Ballweg, DOE)
1985 - Of Soccer Balls and Carbon
Carbon is widely used in nature and industry because of its ability to bond with other elements. In fact, in the early 1980s, scientists didn't even know there was a form of carbon that did not bond to other elements. This landmark 1985 paper identified a new form -- 60 atoms arranged to resemble a soccer ball -- that bonded only to itself. Richard Smalley and his colleagues named it after R. Buckminster Fuller, whose geodesic domes provided a clue as to the structure. Discovering buckminsterfullerene, buckyballs for short, led to the discovery of other novel carbon structures. These structures, called fullerenes and used in biomedical applications, garnered a Nobel Prize in 1996 for Robert Curl Jr., Harold Kroto and Richard Smalley.
H.W. Kroto, J.R. Heath, S.C. O'Brien, R.F. Curl, and R.E. Smalley, "C-60: Buckminsterfullerene." Nature 318(6042), 162-163 (1985). [DOI: 10.1038/318162a0]. Subscription required: contact your local librarian to access. (Image credit: public domain)
1984 - The Nature of Quarks in Protons
As a good chef will tell you, if you don't understand the ingredients, you can't control the menu. Scientists knew by 1984 that the protons and neutrons at the center of the atom were "made" of quarks, but they lacked the pivotal insights to understand how this internal structure of protons and neutrons changes when many of them are very close to each other in an atomic nucleus. In this landmark 1984 paper, scientists presented the results of blasting nuclei of different atoms with beams of electrons at DOE's Stanford Linear Accelerator Center. The results showed that the quark structure of the individual protons and neutrons embedded in a nucleus doesn't match the quark structure of free or individual protons and neutrons. This work, which began with a mere 80 hours of beam time at SLAC, highlighted the importance of considering the quark structure of protons, neutrons and nuclei in nuclear physics and went on to motivate the physicists who came to build DOE's Jefferson Laboratory.
R.G. Arnold, P.E. Bosted, C.C. Chang, J. Gomez, A.T. Katramatou, G.G. Petratos, A.A. Rahbar, S.E. Rock, A.F. Sill, Z.M. Szalata, A. Bodek, N. Giokaris, D.J. Sherden, B.A. Mecking, and R.M. Lombard, "Measurements of the A dependence of deep-inelastic electron scattering from nuclei." Physical Review Letters 52, 727 (1984). [DOI: 10.1103/PhysRevLett.52.727]. Subscription required: contact your local librarian for access. (Image credit: Brookhaven National Laboratory)
1978 - Confining a Tokamak's Plasma
To confine the fourth state of matter (a plasma, or hot ionized gas), the surrounding walls must be insulated. In donut-shaped tokamaks, electrical currents in the plasma are used to confine the plasma within a helical magnetic field. Early methods to sustain the electrical current meant the plasmas could only be confined for a short time. In a landmark 1978 paper, Nathaniel "Nat" Fisch from the Massachusetts Institute of Technology proposed a current-sustaining technique that would allow continuous, steady-state operation to be realized. The approach is used routinely in present-day test reactors.
N.J. Fisch, "Confining a tokamak plasma with rf-driven currents." Physical Review Letters 41(13), 873 (1978). [DOI: 10.1103/PhysRevLett.41.873]. Subscription required: contact your local librarian for access. (Photo credit: Ron Levenson, MIT, CC BY 3.0)
1977 - Getting to the Bottom...of Quarks
Quarks are building blocks for matter. By the early 1970s, four types of quarks have been discovered. Calculations predicted there were more types of quarks, but scientists couldn't prove it. In 1977, Leon Lederman led a team from Fermilab, Columbia University, and Stony Brook University in discovering a new elementary particle -- the bottom quark along with its antiquark. The bottom (or b) quark, which some call the beauty quark, was discovered at Fermilab, soon confirmed by experiments in Europe, and is now a frequent decay product at the Large Hadron Collider at CERN. Located in Switzerland, CERN, or the European Organization for Nuclear Research, is where physicists and engineers use massive, complex instruments to study quarks and other elementary particles.
S.W. Herb, D.C. Hom, L.M. Lederman, J.C. Sens, H.D. Snyder, J.K. Yoh, J.A. Appel, B.C. Brown, C.N. Brown, W.R. Innes, K. Ueno, T. Yamanouchi, A.S. Ito, H. JÓ§stlein, D.M. Kaplan, and R.D. Kephart, "Observation of a dimuon resonance at 9.5 GeV in 400-GeV proton-nucleus collisions." Physical Review Letters 39(5), 252-255 (1977). Subscription required: contact your local librarian for access. (Photo credit: Fermilab)
1977 - Seeing with Sugar
Nuclear medicine owes its existence to work that grew out of DOE and its predecessor research programs. This landmark 1977 paper described how to make 2-18fluoro-D-glucose (18FDG). This sugary compound, developed at DOE's Brookhaven National Laboratory, is a radiotracer. It contains a short-lived radioactive isotope of fluorine and a sugary glucose backbone. If you've ever had a PET scan, you've probably encountered this radiotracer. To prepare for a scan, you're injected with this compound; your cells take it up. Specialized instruments detect the fluorine decay and provide detailed images of your brain, heart and other organs. These PET scans are a new standard medical diagnostic procedure for brain disorders, heart disease and cancer.
T. Ido, C.N. Wan, J.S. Fowler, and A.P. Wolf, "Fluorination with molecular fluorine. A convenient synthesis of 2-deoxy-2-fluoro-D-glucose." Journal of Organic Chemistry 42, 2341-2342 (1977). [DOI: 10.1021/jo00433a037]. Subscription required: contact your local librarian for access. (Photo credit: public domain)
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