Volume 406 Issue 6799, 31 August 2000

The US government's clever interpretation of the law lets stem-cell research proceed, but leaves it exposed to challenges.

One of the question marks hanging over cooperation in structural genomics is how and when the structures of proteins and other macromolecules should be made public.

London

Preliminary discussions are taking place to create an international consortium of research workers in both public research institutions and private companies in structural genomics.

London

The University of Cambridge is hoping to acquire valuable papers containing scientific writings of the physicist and mathematician Sir Isaac Newton.

Munich

The multinational company Novartis Seeds is seeking the support of plant scientists for the introduction of a novel marker gene system that avoids the problems associated with antibiotic-resistant markers.

Washington

US researchers will soon be able to apply for federal grants to study human embryonic stem cells following the long-awaited publication last week by the National Institutes of Health of rules under which such research can proceed.

Tokyo

Japan's Ministry of International Trade and Industry has linked up with the Ministry of Education and the Ministry of Health to launch a new programme aimed at encouraging university researchers to become more entrepreneurial.

Pasadena

Eminent ecologists have endorsed a multi-billion dollar blueprint for the conservation of biodiversity hotspots around the world, deflecting concerns about the scope and cost of the plan.

Washington

State legislators and environmental officials in the United States are watching their colleagues in North Carolina to see what action they take to control ammonia emissions from animal production facilities.

Stunning fossils from Liaoning province have created a boom for Chinese palaeontologists and local farmers alike. Rex Dalton reports from the wild frontier where researchers do battle with the black market.

Evolution emerges unscathed from the battle of creation.

Science needs a new breed of Renaissance man and woman.

The end of the Human Genome Reclamation Project

A non-porous crystal that can inhale and exhale sulphur dioxide gas without imploding offers a new way to make nanostructures. Microscopic gas sensors and switches could soon be created using this simple chemistry.

Studies of an epidemic of sheep cyclopia in the western United States have led to a possible treatment for human skin cancer. The compound that caused the cyclopia inhibits the Hedgehog cellular signalling pathway, which is activated in most basal-cell carcinomas.

Can evolutionary principles be used to automate machine design? A new study evolves robot body parts and nervous systems inside a computer, and then physically builds them, so giving birth to real machines created by virtual evolution.

Pseudomonas aeruginosais a versatile bacterium that colonizes the lungs of most people with cystic fibrosis. Its genome sequence provides clues to the origins of its versatility and its resistance to antibiotics.

The Lorenz attractor is an example of deterministic chaos. Previously, the Lorenz attractor could only be generated by numerical approximations on a computer. Now we have a rigorous proof that confirms its existence.

After it invades a red blood cell of its host, the malaria parasite grows and divides, producing 20-30 new parasites. A newly described channel, found in the outer membrane of infected red blood cells, may provide the parasite with the nutrients it needs to fuel its growth.

Until recently it was assumed that most of the quartz found in mudrocks was eroded from older rocks. A careful study of ancient mudrocks now suggests that the dissolved skeletons of marine plankton are the main source of quartz.

Specification of the vertebrate limb by an embryo requires a complicated set of molecular instructions and, early on, the establishment of a ‘polarizing region’. A transcription factor known as dHAND has now been implicated in specifying the polarizing region.

Hard materials such as metal oxides should contain their internal stresses indefinitely, or at least until they are disturbed. DREADCO chemists hope to use such materials as tiny landmines for killing insects without the need for chemical insecticides.

Birds taking time off from breeding head for their favourite long-haul destinations.

Following the introduction of silicon-based integrated circuitry over three decades ago, the integration density of such circuits has doubled every 12 to 18 months: this observation is known as Moore's law. For this historical trend to continue, significant challenges need to be overcome in several key technological areas. But for many of these challenges, there are at present no known solutions.

The phenomenal rate of increase in the integration density of silicon chips has been sustained in large part by advances in optical lithography — the process that patterns and guides the fabrication of the component semiconductor devices and circuitry. Although the introduction of shorter-wavelength light sources and resolution-enhancement techniques should help maintain the current rate of device miniaturization for several more years, a point will be reached where optical lithography can no longer attain the required feature sizes. Several alternative lithographic techniques under development have the capability to overcome these resolution limits but, at present, no obvious successor to optical lithography has emerged.

The silicon-based microelectronics industry is rapidly approaching a point where device fabrication can no longer be simply scaled to progressively smaller sizes. Technological decisions must now be made that will substantially alter the directions along which silicon devices continue to develop. One such challenge is the need for higher permittivity dielectrics to replace silicon dioxide, the properties of which have hitherto been instrumental to the industry's success. Considerable efforts have already been made to develop replacement dielectrics for dynamic random-access memories. These developments serve to illustrate the magnitude of the now urgent problem of identifying alternatives to silicon dioxide for the gate dielectric in logic devices, such as the ubiquitous field-effect transistor.

Transistors have continuously reduced in size and increased in switching speed since their invention in 1947. The exponential pace of transistor evolution has led to a revolution in information acquisition, processing and communication technologies. And reigning over most digital applications is a single device structure — the field-effect transistor (FET). But as device dimensions approach the nanometre scale, quantum effects become increasingly important for device operation, and conceptually new transistor structures may need to be adopted. A notable example of such a structure is the single-electron transistor, or SET^1,2,3,4. Although it is unlikely that SETs will replace FETs in conventional electronics, they should prove useful in ultra-low-noise analog applications. Moreover, because it is not affected by the same technological limitations as the FET, the SET can approach closely the quantum limit of sensitivity. It might also be a useful read-out device for a solid-state quantum computer.

Computers are physical systems: the laws of physics dictate what they can and cannot do. In particular, the speed with which a physical device can process information is limited by its energy and the amount of information that it can process is limited by the number of degrees of freedom it possesses. Here I explore the physical limits of computation as determined by the speed of light c, the quantum scale ℏ and the gravitational constant G. As an example, I put quantitative bounds to the computational power of an ‘ultimate laptop’ with a mass of one kilogram confined to a volume of one litre.

New ways of handling slurry, rats in transit, and DNA.

Since the invention of the integrated circuit in 1959, the semiconductor industry has improved the productivity of such circuits by 25-30% annually. This Insight focuses on some of the most pressing technological and fundamental problems that are - or will be - faced by the semiconductor industry if it is to continue to satisfy consumer demand for speed and computational power.