1,794 research outputs found
Dynamic root growth in response to depth-varying soil moisture availability:a rhizobox study
Plant roots are highly adaptable, but their adaptability is not included in crop and land surface models. They rely on a simplified representation of root growth, which is independent of soil moisture availability. Data of subsurface processes and interactions, needed for model setup and validation, are scarce. Here we investigated soil-moisture-driven root growth. To this end, we installed subsurface drip lines and small soil moisture sensors (0.2 L measurement volume) inside rhizoboxes (length × width × height of 45 × 7.5 × 45 cm). The development of the vertical soil moisture and root growth profiles is tracked with a high spatial and temporal resolution. The results confirm that root growth is predominantly driven by vertical soil moisture distribution, while influencing soil moisture at the same time. Besides support for the functional relationship between the soil moisture and the root density growth rate, the experiments also suggest that the extension of the maximum rooting depth will stop if the soil moisture at the root tip drops below a threshold value. We show that even a parsimonious one-dimensional water balance model, driven by the water input flux (irrigation), can be convincingly improved by implementing root growth driven by soil moisture availability
Gate-tunable band structure of the LaAlO-SrTiO interface
The 2-dimensional electron system at the interface between LaAlO and
SrTiO has several unique properties that can be tuned by an externally
applied gate voltage. In this work, we show that this gate-tunability extends
to the effective band structure of the system. We combine a magnetotransport
study on top-gated Hall bars with self-consistent Schr\"odinger-Poisson
calculations and observe a Lifshitz transition at a density of
cm. Above the transition, the carrier density of one
of the conducting bands decreases with increasing gate voltage. This surprising
decrease is accurately reproduced in the calculations if electronic
correlations are included. These results provide a clear, intuitive picture of
the physics governing the electronic structure at complex oxide interfaces.Comment: 14 pages, 4 figure
Magnetically induced chessboard pattern in the conductance of a Kondo quantum dot
We quantitatively describe the main features of the magnetically induced
conductance modulation of a Kondo quantum dot -- or chessboard pattern -- in
terms of a constant-interaction double quantum dot model. We show that the
analogy with a double dot holds down to remarkably low magnetic fields. The
analysis is extended by full 3D spin density functional calculations.
Introducing an effective Kondo coupling parameter, the chessboard pattern is
self-consistently computed as a function of magnetic field and electron number,
which enables us to quantitatively explain our experimental data.Comment: 4 pages, 3 color figure
Josephson supercurrent in a topological insulator without a bulk shunt
A Josephson supercurrent has been induced into the three-dimensional
topological insulator Bi1.5Sb0.5Te1.7Se1.3. We show that the transport in
Bi1.5Sb0.5Te1.7Se1.3 exfoliated flakes is dominated by surface states and that
the bulk conductivity can be neglected at the temperatures where we study the
proximity induced superconductivity. We prepared Josephson junctions with
widths in the order of 40 nm and lengths in the order of 50 to 80 nm on several
Bi1.5Sb0.5Te1.7Se1.3 flakes and measured down to 30 mK. The Fraunhofer patterns
unequivocally reveal that the supercurrent is a Josephson supercurrent. The
measured critical currents are reproducibly observed on different devices and
upon multiple cooldowns, and the critical current dependence on temperature as
well as magnetic field can be well explained by diffusive transport models and
geometric effects
Treatment of multidrug-resistant tuberculosis using therapeutic drug monitoring:first experiences with sub-300 mg linezolid dosages using in-house made capsules
Correlation between Superconductivity, Band Filling and Electron Confinement at the LaAlO-SrTiO Interface
By combined top- and backgating, we explore the correlation of
superconductivity with band filling and electron confinement at the
LaAlO-SrTiO interface. We find that the top- and backgate voltages have
distinctly different effects on the superconducting critical temperature,
implying that the confining potential well has a profound effect on
superconductivity. We investigate the origin of this behavior by comparing the
gate-dependence of to the corresponding evolution of the band filling
with gate voltage. For several backgate voltages, we observe maximum to
consistently coincide with a kink in tuning the band filling for high topgate
voltage. Self-consistent Schr\"odinger-Poisson calculations relate this kink to
a Lifshitz transition of the second subband. These results establish a
major role for confinement-induced subbands in the phase diagram of SrTiO
surface states, and establish gating as a means to control the relative energy
of these states.Comment: 17 pages, 5 figure
How to Assure That Farmers Apply New Technology According to Good Agricultural Practice: Lessons From Dutch Initiatives
The application of Good Agricultural Practice (GAP) contributes to many aspects of sustainable farming, including integrated control of weeds, diseases, and pests, and optimization of fertilization and irrigation. It is a relatively neglected issue in debates regarding the application of new technology, such as genetic modification (GM), which often revolve around the intrinsic properties of a GM crop allegedly leading to unsatisfactory performance. However, the performance largely depends on the agronomic and institutional embedding of applying new technology, which generally applies to all crops, whether conventional or GM. We describe and discuss four cases in which the government or private partners in the production chain regulate this, using legal measures, incentives, or mutual agreements, or a combination thereof. These cases serve as a starting point for a discussion on how GAP can be stimulated, organized, and guaranteed. We argue that next to the government, also seed suppliers, NGOs, and buyers, as well as farmers can be drivers for the application of GAP when tools are available that enable farmers to make optimal farming choices
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