681 research outputs found
Mapping regional social enterprise ecosystems in India: Framework and indicators
In this paper we briefly review social enterprise in the context of India before developing a conceptual framework highlighting the different components that make up a regional social enterprise ecosystem (including entrepreneurs, financial and non-financial support, education and research, communication, collaboration and networks, government policy, and the local economy and context). Based on these, we discuss the availability of relevant data before developing a set of indicators for describing the components in different regional ecosystems across India. This paper is the first of a project documenting nine regional social enterprise ecosystems across India
High-temperature excess current and quantum suppression of electronic backscattering in a 1-D system
We consider the electronic current through a one-dimensional conductor in the
ballistic transport regime and show that the quantum oscillations of a weakly
pinned single scattering target results in a temperature- and bias-voltage
independent excess current at large bias voltages. This is a genuine effect on
transport that derives from an exponential reduction of electronic
backscattering in the elastic channel due to quantum delocalization of the
scatterer and from suppression of low-energy electron backscattering in the
inelastic channels caused by the Pauli exclusion principle. We show that both
the mass of the target and the frequency of its quantum vibrations can be
measured by studying the differential conductance and the excess current. We
apply our analysis to the particular case of a weakly pinned C60 molecule
encapsulated by a single-wall carbon nanotube and find that the discussed
phenomena are experimentally observable.Comment: 4 pages, 4 figure
Linking ecological health to co-occurring organic and inorganic chemical stressors in a groundwater-fed stream system
Sonne AT, Rasmussen JJ, Höss S, Traunspurger W, Bjerg PL, McKnight US. Linking ecological health to co-occurring organic and inorganic chemical stressors in a groundwater-fed stream system. SCIENCE OF THE TOTAL ENVIRONMENT. 2018;642:1153-1162.Freshwaters are among the most endangered ecosystems worldwide, due predominantly to excessive anthropogenic practices compromising the future provisioning of ecosystem services. Despite increased awareness of the role of multiple stressors in accounting for ecological degradation in mixed land-use stream systems, risk assessment approaches applicable in field settings are still required. This study provides a first indication for ecological consequences of the interaction of organic and inorganic chemical stressors, not typically evaluated together, which may provide a missing link enabling the reconnection of chemical and ecological findings. Specifically, impaired ecological conditions - represented by lower abundance of meiobenthic individuals - were observed in the hyporheic zone where a contaminant groundwater plume discharged to the stream. These zones were characterized by high xenobiotic organic concentrations, and strongly reduced groundwater (e.g. elevated dissolved iron and arsenic) linked to the dissolution of iron hydroxides (iron reduction) caused by the degradation of xenobiotic compounds in the plume. Further research is still needed to separate whether impact is driven by a combined effect of organic and inorganic stressors impacting the ecological communities, or whether the conditions - when present simultaneously - are responsible for enabling a specific chemical stressors availability (e.g. trace metals), and thus toxicity, along the study stream. Regardless, these findings suggest that benthic meioinvertebrates are promising indicators for supporting biological assessments of stream systems to sufficiently represent impacts resulting from the co-occurrence of stressors in different stream compartments. Importantly, identification of the governing circumstances is crucial for revealing key patterns and impact drivers that may be needed in correctly prioritizing stressor impacts in these systems. This study further highlights the importance of stream-aquifer interfaces for investigating chemical stressor effects in multiple stressor systems. This will require holistic approaches for linking contaminant hydrogeology and eco(toxico)logy in order to positively influence the sustainable management of water resources globally. (C) 2018 Elsevier B.V. All rights reserved
Selfoscillations of Suspended Carbon Nanotubes with a Deflection Sensitive Resistance under Voltage Bias
We theoretically investigate the electro-mechanics of a Suspended Carbon
Nanotube with a Deflection Sensitive Resistance subjected to a homogeneous
Magnetic Field and a constant Voltage Bias. We show that, (with the exception
of a singular case), for a sufficiently high magnetic field the
time-independent state of charge transport through the nanotube becomes
unstable to selfexcitations of the mechanical vibration accompanied by
oscialltions in the voltage drop and current across the nanotube.Comment: 4 pages, 1 figur
Non-Equilibrium and Quantum Coherent Phenomena in the Electromechanics of Suspended Nanowires
Strong coupling between electronic and mechanical degrees of freedom is a
basic requirement for the operation of any nanoelectromechanical device. In
this Review we consider such devices and in particular investigate the
properties of small tunnel-junction nanostructures that contain a movable
element in the form of a suspended nanowire. In these systems, electrical
current and charge can be concentrated to small spatial volumes resulting in
strong coupling between the mechanics and the charge transport. As a result, a
variety of mesoscopic phenomena appear, which can be used for the transduction
of electrical currents into mechanical operation. Here we will in particular
consider nanoelectromechanical dynamics far from equilibrium and the effect of
quantum coherence in both the electronic and mechanical degrees of freedom in
the context of both normal and superconducting nanostructures.Comment: 20 pages, 13 figures, figures update
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