4 research outputs found
Chemical intervention in plant sugar signalling increases yield and resilience
The pressing global issue of food insecurity due to population growth, diminishing land and variable climate can only be addressed in agriculture by improving both maximum crop yield potential and resilience. Genetic modification is one potential solution, but has yet to achieve worldwide acceptance, particularly for crops such as wheat. Trehalose-6-phosphate (T6P), a central sugar signal in plants, regulates sucrose use and allocation, underpinning crop growth and development. Here we show that application of a chemical intervention strategy directly modulates T6P levels in planta. Plant-permeable analogues of T6P were designed and constructed based on a ‘signalling-precursor’ concept for permeability, ready uptake and sunlight-triggered release of T6P in planta. We show that chemical intervention in a potent sugar signal increases grain yield, whereas application to vegetative tissue improves recovery and resurrection from drought. This technology offers a means to combine increases in yield with crop stress resilience. Given the generality of the T6P pathway in plants and other small-molecule signals in biology, these studies suggest that suitable synthetic exogenous small-molecule signal precursors can be used to directly enhance plant performance and perhaps other organism function
The Hubbard model within the equations of motion approach
The Hubbard model has a special role in Condensed Matter Theory as it is
considered as the simplest Hamiltonian model one can write in order to describe
anomalous physical properties of some class of real materials. Unfortunately,
this model is not exactly solved except for some limits and therefore one
should resort to analytical methods, like the Equations of Motion Approach, or
to numerical techniques in order to attain a description of its relevant
features in the whole range of physical parameters (interaction, filling and
temperature). In this manuscript, the Composite Operator Method, which exploits
the above mentioned analytical technique, is presented and systematically
applied in order to get information about the behavior of all relevant
properties of the model (local, thermodynamic, single- and two- particle ones)
in comparison with many other analytical techniques, the above cited known
limits and numerical simulations. Within this approach, the Hubbard model is
shown to be also capable to describe some anomalous behaviors of the cuprate
superconductors.Comment: 232 pages, more than 300 figures, more than 500 reference
Two energy scales in the spin excitations of the high-temperature superconductor La2-xSrxCuO4
The excitations responsible for producing high-temperature superconductivity
in the cuprates have not been identified. Two promising candidates are
collective spin excitations and phonons. A recent argument against spin
excitations has been their inability to explain structures seen in electronic
spectroscopies such as photoemission and tunnelling. Here we use inelastic
neutron scattering to demonstrate that collective spin excitations in optimally
doped LaSrCuO are more structured than previously thought.
The excitations have a two component structure with a low-frequency component
strongest around 18 meV and a broader component strongest near 40-70 meV. The
second component carries most of the spectral weight and its energy matches
structure seen in photoemission and tunnelling spectra in the range 50-90 meV.
Our results demonstrate that collective spin excitations can explain features
of quasiparticle spectroscopies and are therefore likely to be the strongest
coupled excitations.Comment: accepted for publication in Nature Physics, original submissio