Science And Tech

Virtual Childbirth Simulator Improves Safety of High-Risk Deliveries

Newly developed computer software combined with magnetic resonance imaging (MRI) of a fetus may help physicians better assess a womans potential for a difficult childbirth. Results of a study using the new software were presented November 29 at the annual meeting of the Radiological Society of North America (RSNA). Because a womans birth canal is curved and not much wider than a fetuss head, a baby must move through the canal in a specific sequence of maneuvers. A failure in the process, such as a head turned the wrong way at the wrong time, can result in dystocia, or difficult labor.
“The mechanics of the human birth canal make for a very complicated delivery process compared to other mammals,” said Olivier Ami, M.D., Ph.D., an obstetrician in the Department of Radiology at Antoine Béclères Hospital, Université Paris Sud, France. “We now have computer-simulated childbirth to identify potential problems.”
Using the new software, called PREDIBIRTH, Dr. Ami and a team of researchers processed MR images of 24 pregnant women. The result was a three-dimensional (3-D) reconstruction of both the pelvis and the fetus along with 72 possible trajectories of the babys head through the birth canal. Based on these simulations, the program scored each mothers likelihood of a normal birth.
“This goes beyond simple imaging,” Dr. Ami said. “The software simulates the properties of potential deliveries.”
For purposes of the study, the PREDIBIRTH scores were computed retrospectively and measured against delivery outcomes for the 24 women. Thirteen women delivered normally. These deliveries were scored as highly favorable by the simulator. Three women who delivered by elective cesarean-section (C-section) — two of which involved babies of excessive weight — were scored at high risk for dystocia.
Of the five women delivered by emergency C-section, two involved heart rhythm abnormalities and were scored mildly favorable and favorable. Three involved obstructed labor, all of whom scored at high risk of dystocia. Three women delivered with vacuum extraction and had mildly favorable simulator scores.
“The results in predicting dystocia were highly accurate,” Dr. Ami said. “Our simulation predictions seem to be a significant improvement over pelvimetry.”
Pelvimetry, which measures the pelvis manually or by imaging to determine its adequacy for childbirth, is commonly used but not entirely reliable, according to Dr. Ami.
“A small pelvis may be able to deliver without problems, and a big pelvis might require mechanical help during childbirth,” he said. “This uncertainty raises the rate of C-sections.”
In the U.S., C-sections account for approximately one-third of all births. In France, the rate of mechanical problems is 30 percent, two-thirds of which are emergency procedures.
“An emergency C-section has six to seven times more morbidity and mortality than a planned C-section,” Dr. Ami said. “With this virtual childbirth software, the majority of C-sections could be planned rather than emergency, and difficult instrumental extractions might disappear in the near future.”
Coauthors are Lucie Cassagnes, M.D., Jean-Francois Uhl, M.D., Didier Lemery, M.D., Ph.D., Vincent Delmas, Gérard Mage, M.D., Ph.D., and Louis Boyer, M.D.

One of the World’s Smallest Electronic Circuits Created

A team of scientists, led by Guillaume Gervais from McGill’s Physics Department and Mike Lilly from Sandia National Laboratories, has engineered one of the world’s smallest electronic circuits. It is formed by two wires separated by only about 150 atoms or 15 nanometers (nm).
The discovery, published in the journal Nature Nanotechnology, could have a significant effect on the speed and power of the ever smaller integrated circuits of the future in everything from smartphones to desktop computers, televisions and GPS systems.
This is the first time that anyone has studied how the wires in an electronic circuit interact with one another when packed so tightly together. Surprisingly, the authors found that the effect of one wire on the other can be either positive or negative. This means that a current in one wire can produce a current in the other one that is either in the same or the opposite direction. This discovery, based on the principles of quantum physics, suggests a need to revise our understanding of how even the simplest electronic circuits behave at the nanoscale.
In addition to the effect on the speed and efficiency of future electronic circuits, this discovery could also help to solve one of the major challenges facing future computer design. This is managing the ever-increasing amount of heat produced by integrated circuits
Well-known theorist Markus Büttiker speculates that it may be possible to harness the energy lost as heat in one wire by using other wires nearby. Moreover, Buttiker believes that these findings will have an impact on the future of both fundamental and applied research in nanoelectronics.
The research was funded by the Natural Sciences and Engineering Research Council of Canada, the Fonds de recherche Nature et Technologies of Quebec, the Canadian Institute for Advanced Research and the Center of Integrated Nanotechnologies at Sandia National

Supercomputer Reveals New Details Behind Drug-Processing Protein Model

Supercomputer simulations at the Department of Energy’s Oak Ridge National Laboratory are giving scientists unprecedented access to a key class of proteins involved in drug detoxification.
Jerome Baudry and Yinglong Miao, who are jointly affiliated with ORNL and the University of Tennessee, have performed simulations to observe the motions of water molecules in a class of enzymes called P450s. Certain types of P450 are responsible for processing a large fraction of drugs taken by humans.
The supercomputer simulations were designed to help interpret ongoing neutron experiments.
“We simulated what happens in this enzyme over a time scale of 0.3 microseconds, which sounds very fast, but from a scientific point of view, it’s a relatively long time,” Baudry said. “A lot of things happen at this scale that had never been seen before. It’s a computational tour de force to be able to follow that many water molecules for that long.”
The team’s study of the water molecules’ movements contributes to a broader understanding of drug processing by P450 enzymes. Because some populations have a slightly different version of the enzymes, scientists hypothesize that mutations could partially explain why people respond differently to the same drug. One possibility is that the mutations might shut down the channels that bring water molecules in and out of the enzyme’s active site, where the chemical modification of drugs takes place. This could be investigated by using the computational tools developed for this research.
By simulating how water molecules move in and out of the protein’s centrally located active site, the team clarified an apparent contradiction between experimental evidence and theory that had previously puzzled researchers. X-ray crystallography, which provides a static snapshot of the protein, had shown only six water molecules present in the active site, whereas experimental observations indicated a higher number of water molecules would be present in the enzyme.
“We found that even though there can be many water molecules — up to 12 at a given time that get in and out very quickly — if you look at the average, those water molecules prefer to be at a certain location that corresponds to what you see in the crystal structure,” Miao said. “It’s a very dynamic hydration process that we are exploring with a combination of neutron scattering experiments and simulation.”
The simulation research is published in Biophysical Journal as “Active-Site Hydration and Water Diffusion in Cytochrome P450cam: A Highly Dynamic Process.”
The team was supported by an Experimental Program to Stimulate Competitive Research (EPSCOR) grant from the DOE Office of Science and funding from the University of Tennessee. Computing time on the Kraken supercomputer was supported by a National Science Foundation TeraGrid award.
ORNL is managed by UT-Battelle for the Department of Energy’s Office of Science.

New Switch Could Improve Electronics

Researchers at the University of Pittsburgh have invented a new type of electronic switch that performs electronic logic functions within a single molecule. The incorporation of such single-molecule elements could enable smaller, faster, and more energy-efficient electronics.
The research findings, supported by a $1 million grant from the W.M. Keck Foundation, were published online in the Nov. 14 issue of Nano Letters.
“This new switch is superior to existing single-molecule concepts,” said Hrvoje Petek, principal investigator and professor of physics and chemistry in the Kenneth P. Dietrich School of Arts and Sciences and codirector of the Petersen Institute for NanoScience and Engineering (PINSE) at Pitt. “We are learning how to reduce electronic circuit elements to single molecules for a new generation of enhanced and more sustainable technologies.”
The switch was discovered by experimenting with the rotation of a triangular cluster of three metal atoms held together by a nitrogen atom, which is enclosed entirely within a cage made up entirely of carbon atoms. Petek and his team found that the metal clusters encapsulated within a hollow carbon cage could rotate between several structures under the stimulation of electrons. This rotation changes the molecule’s ability to conduct an electric current, thereby switching among multiple logic states without changing the spherical shape of the carbon cage. Petek says this concept also protects the molecule so it can function without influence from outside chemicals.
Because of their constant spherical shape, the prototype molecular switches can be integrated as atom-like building blocks the size of one nanometer (100,000 times smaller than the diameter of a human hair) into massively parallel computing architectures.
The prototype was demonstrated using an Sc3N@C80 molecule sandwiched between two electrodes consisting of an atomically flat copper oxide substrate and an atomically sharp tungsten tip. By applying a voltage pulse, the equilateral triangle-shaped Sc3N could be rotated predictably among six logic states.
The research was led by Petek in collaboration with chemists at the Leibnitz Institute for Solid State Research in Dresden, Germany, and theoreticians at the University of Science and Technology of China in Hefei, People’s Republic of China. The experiments were performed by postdoctoral researcher Tian Huang and research assistant professor Min Feng, both in Pitt’s Department of Physics and Astronomy.

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