30 MAY 2014 • VOL 344 ISSUE 6187 969 SCIENCE sciencemag.org
Light passing through crossed polarizing
filters is effectively extinguished, but a bire-
fringent crystal placed between crossed po-
larizers rotates the direction of polarization
so that it can pass through the second filter.
This method may be used to identify crystals that are birefringent, such as the urate
salt crystals associated with gout. Stress can
create local regions in materials that are birefringent. Crystals can be examined for imperfections, and even noncrystalline plastics
can show stressed regions (see the figure).
Most x-rays used for diffraction experiments are polarized because the monochromators that select the wavelength are
essentially x-ray mirrors. The polarization,
like optical glare, is normally a nuisance
that is dealt with in a footnote of the experiment; “the data were corrected for polarization effects.” Indeed, that x-ray birefringence
may introduce errors into intensity measurements and compromise comparisons
between measurements at different wavelengths has been pointed out (2).
Palmer et al. show that polarization of x-rays can also be put to good use. Although
the interaction of a crystal with visible light
is a collective phenomenon that reflects the
symmetry properties of the entire crystal,
the energy of the x-ray beam can be tuned
to coincide with the absorption edge of a
particular element. The interaction between
Mapping bond orientations
with polarized x-rays
Lighting up under stress. Polarized light microscopy can provide a simple way to identify regions of stress in a material. A
clear polymer spoon and fork show regions where internal stress aligns the otherwise disordered polymer molecules. These
regions become birefringent; the colors result from variations in the stress. Palmer et al. exploited a birefingent effect in the
x-ray region to map ordering and disordering of bond orientation in host-guest crystals.
By Sven Lidin
Regions of bond order and disorder are revealed
Department of Polymer and Materials Chemistry, Lund
University, Sweden. E-mail: firstname.lastname@example.org
arose from a risk-sharing arrangement between Vertex Pharmaceuticals and the Cystic
Fibrosis Foundation, and has been successful
in other contexts (e.g., multidrug-resistant
tuberculosis and malaria).
Funding for basic research. Infectious
diseases account for ~5% of the U.S. National Institutes of Health (NIH)’s research
funding. One study estimated that a 10%
increase in disease-specific funding by NIH
yielded a 4.5% increase in the number of
related drugs entering clinical testing (8).
Given the possible national security threat
from multidrug-resistant infections, the
U.S. Department of Defense would represent a logical additional source for increased support. Bolstering public funding
for basic research would increase the pool
of knowledge and new experimental therapies, as well as speed development of riskier
therapeutic modalities, such as targeted biologics stimulating an immune response to
pathogens and therapeutic vaccines.
Conserving antibiotic resources through
stewardship could be achieved through renewed public health efforts to reduce inappropriate prescribing and overconsumption
of antibiotics by humans and in agriculture. One way to foster antibiotic conservation may involve “delinkage,” separating
the funding of antibiotic R&D investments
from volume-driven drug sales (9). New
policies should help ensure adequate reward for antibiotic R&D, as well as for all
institutions that contribute to the societal
need to conserve these life-saving drugs for
future generations. ■
REFERENCES AND NOTES
1. A. Coates, Y. Hu, R. Bax, C. Page, Nat. Rev. Drug Discov.
1, 895 (2002).
2. J. H. Rex et al ., Lancet Infect. Dis. 13, 269 (2013).
3. S. J. Projan, Curr. Opin. Microbiol. 6, 427 (2003).
4. H. W. Boucher et al ., Clin. Infect. Dis. 56, 1685 (2013).
5. T.J.Hwang, PLOS ONE 8,e71966(2013).
6. J. A. DiMasi et al ., Clin.Pharmacol. Ther. 87, 272 (2010).
7. N. S. Do wning et al. , JAMA 311, 368 (2014).
8. M. E. Blume-Kohout, J. Policy Anal. Manage. 31, 641
9. D. Holmes,Nat.Med. 20, 320 (2014).
This research was supported by grants (to T. J. H.)
from the Interfaculty Initiative in Health Policy
(Cordiero Fellowship) and Center for American
Political Studies, both at Harvard University. A.S. K.
is supported by the Greenwall Faculty Scholarship,
a Harvard Program in Therapeutic Science Ignition
Award, and the Robert Wood Johnson Investigator
Award in Health Policy Research. We thank J. M.
Franklin for helpful comments. The content is solely
the responsibility of the authors. The funders had no
role in study design, manuscript drafting, or decision
to publish. The authors declare no conflicts of interest.