Science  05 Jul 2013:
Vol. 341, Issue 6141, pp. 15
  1. Molecular Wires Show Strong Magnetic Potential


    The capacity of computer hard drives has been skyrocketing for decades, thanks partly to improvements in the magnetic sensors used to read them. Published in Science this week, researchers led by Wilfred van der Wiel, a physicist at the University of Twente in the Netherlands, describe a new room-temperature magnetic sensor three times as sensitive as the previous champ.

    The new material is made of dye molecules called DXP. Normally DXP is nonmagnetic. But when the researchers squeezed it into the pores of latticelike minerals called zeolites, DXP formed molecular wires in which a quantum effect called Pauli exclusion came into play. As a result, any electrons moving through the wire stopped in their tracks when the wire encountered a magnetic field. That electron-blocking property, called magnetoresistance, is the key to reading magnetic bits.

    The wires are still too small to be used in computers. But the scientists say that they may be useful for touch screens and novel magnetic sensing devices.

  2. Monarchs Medicate Their Young


    An overly infected monarch can't emerge from its coccoon.


    For the monarch butterfly, milkweeds are a multipurpose plant. When ingested, their toxins not only make the insect unpalatable to birds and other predators, but they also fight infection, says Jacobus de Roode, an evolutionary biologist from Emory University in Atlanta.

    De Roode discovered that different milkweed species reduce protozoan growth in caterpillars to varying degrees in proportion to the amount of toxin they produce. Caterpillars don't seem to know this, but the adults do, De Roode reported last week at Evolution 2013 in Snowbird, Utah. By a 2-to-1 margin, infected adult butterflies choose to lay eggs on the milkweed that will most retard protozoan growth, thus medicating their young. "Just the idea that they are selecting plants to fight the parasites of their offspring is really cool," says evolutionary biologist Curtis Lively of Indiana University, Bloomington.

  3. Map Offers Millennium Of Earthquake Records

    Researchers meeting last week in Pavia, Italy, were presented with a new worldwide seismic database based on tens of thousands of earthquake records stretching back more than 1000 years. The Global Earthquake Model (GEM) Foundation, which supported the research largely with contributions from insurance companies, says that the database is part of a push to make the long-fragmented field of earthquake forecasting more open and systematic.

    "Everyone knew we needed to do this," says GEM's co-founder, Ross Stein, a seismologist with the U.S. Geological Survey. "No one was willing to put the money up. GEM did." Other GEM projects include a global map of tectonic strain and socioeconomic studies aimed at estimating potential casualties and damage from future quakes.

    While geoscientists welcomed the effort, some cautioned that no amount of data can overcome the deep uncertainties inherent in Earth faulting processes.

Log in to view full text

Log in through your institution

Log in through your institution

Stay Connected to Science

Navigate This Article