658 research outputs found
Translation Mechanisms in Socio-Technical Niches. A case study of Dutch river management
This paper makes three contributions to the field of transition research. First, it sheds light on how the concept of translation can contribute to a better understanding of agency in niche development. Second, it articulates how the local-global distinction in the Strategic Niche Management (SNM) approach relates to the levels in the Multi-Level Perspective. Third, the article is empirically novel by presenting a radical sustainable innovation in Dutch water management (‘New Rivers’).Sustainability transitions, translations, strategic niche management, river management
Strong coupling between single-electron tunneling and nano-mechanical motion
Nanoscale resonators that oscillate at high frequencies are useful in many
measurement applications. We studied a high-quality mechanical resonator made
from a suspended carbon nanotube driven into motion by applying a periodic
radio frequency potential using a nearby antenna. Single-electron charge
fluctuations created periodic modulations of the mechanical resonance
frequency. A quality factor exceeding 10^5 allows the detection of a shift in
resonance frequency caused by the addition of a single-electron charge on the
nanotube. Additional evidence for the strong coupling of mechanical motion and
electron tunneling is provided by an energy transfer to the electrons causing
mechanical damping and unusual nonlinear behavior. We also discovered that a
direct current through the nanotube spontaneously drives the mechanical
resonator, exerting a force that is coherent with the high-frequency resonant
mechanical motion.Comment: Main text 12 pages, 4 Figures, Supplement 13 pages, 6 Figure
The ethanolamide metabolite of DHA, docosahexaenoylethanolamine, shows immunomodulating effects in mouse peritoneal and RAW264.7 macrophages: evidence for a new link between fish oil and inflammation
Several mechanisms have been proposed for the positive health effects associated with dietary consumption of long-chain n-3 PUFA (n-3 LC-PUFA) including DHA (22 : 6n-3) and EPA (20 : 5n-3). After dietary intake, LC-PUFA are incorporated into membranes and can be converted to their corresponding N-acylethanolamines (NAE). However, little is known on the biological role of these metabolites. In the present study, we tested a series of unsaturated NAE on the lipopolysaccharide (LPS)-induced NO production in RAW264.7 macrophages. Among the compounds tested, docosahexaenoylethanolamine (DHEA), the ethanolamide of DHA, was found to be the most potent inhibitor, inducing a dose-dependent inhibition of NO release. Immune-modulating properties of DHEA were further studied in the same cell line, demonstrating that DHEA significantly suppressed the production of monocyte chemotactic protein-1 (MCP-1), a cytokine playing a pivotal role in chronic inflammation. In LPS-stimulated mouse peritoneal macrophages, DHEA also reduced MCP-1 and NO production. Furthermore, inhibition was also found to take place at a transcriptional level, as gene expression of MCP-1 and inducible NO synthase was inhibited by DHEA. To summarise, in the present study, we showed that DHEA, a DHA-derived NAE metabolite, modulates inflammation by reducing MCP-1 and NO production and expression. These results provide new leads in molecular mechanisms by which DHA can modulate inflammatory processes
Phase transitions on the surface of a carbon nanotube
A suspended carbon nanotube can act as a nanoscale resonator with remarkable
electromechanical properties and the ability to detect adsorption on its
surface at the level of single atoms. Understanding adsorption on nanotubes and
other graphitic materials is key to many sensing and storage applications. Here
we show that nanotube resonators offer a powerful new means of investigating
fundamental aspects of adsorption on carbon, including the collective behaviour
of adsorbed matter and its coupling to the substrate electrons. By monitoring
the vibrational resonance frequency in the presence of noble gases, we observe
the formation of monolayers on the cylindrical surface and phase transitions
within these monolayers, and simultaneous modification of the electrical
conductance. The monolayer observations also demonstrate the possibility of
studying the fundamental behaviour of matter in cylindrical geometry.Comment: Unpublished; 7 pages with 4 figures plus 3 pages of supplementary
materia
Zeeman energy and spin relaxation in a one-electron quantum dot
We have measured the relaxation time, T1, of the spin of a single electron
confined in a semiconductor quantum dot (a proposed quantum bit). In a magnetic
field, applied parallel to the two-dimensional electron gas in which the
quantum dot is defined, Zeeman splitting of the orbital states is directly
observed by measurements of electron transport through the dot. By applying
short voltage pulses, we can populate the excited spin state with one electron
and monitor relaxation of the spin. We find a lower bound on T1 of 50
microseconds at 7.5 T, only limited by our signal-to-noise ratio. A continuous
measurement of the charge on the dot has no observable effect on the spin
relaxation.Comment: Replaced with the version published in Phys. Rev. Let
The association of socioeconomic status on treatment strategy in patients with stage I and II breast cancer in the Netherlands
BACKGROUND: Previous studies have shown that socioeconomic status (SES) influences breast cancer therapy. However, these studies were performed in countries with unequal access to healthcare. Therefore, the aim of this study is to investigate whether SES also contributes to the likelihood of receiving a certain therapy in the Netherlands, a country with supposedly equal access to healthcare. MATERIALS AND METHODS: From the Netherlands Cancer Registry, 105,287 patients with newly diagnosed stage I or II breast cancer diagnosed between 2011 and 2018 were selected for analysis. SES was calculated from the average incomes of each postal code, which were divided into 10 deciles. Primary outcome was the effect of SES on the likelihood of undergoing surgery and secondary outcome was the effect of SES on the likelihood of the type of surgery. Both outcomes were corrected for patient, tumor, and hospital characteristics and were expressed as odds ratio (OR) with 95% confidence interval (CI). RESULTS: SES did not affect the likelihood of a breast cancer patient to undergo surgery (OR 1.00 per 10% stratum). In contrast, increased age and higher tumor stage were the most important factors determining whether patients underwent surgery. Patients with higher SES were less likely to undergo mastectomy (OR 0.98). Additionally, more recently diagnosed patients were less likely to undergo mastectomy (OR 0.93 per year) while patients with higher tumor stage were more likely to undergo mastectomy (OR 3.42). CONCLUSION: SES does not affect whether a patient undergoes surgery; however, higher SES increased the likelihood of BCT
Pumping of vibrational excitations in a Coulomb blockaded suspended carbon nanotube
Low-temperature transport spectroscopy measurements on a suspended few-hole
carbon nanotube quantum dot are presented, showing a gate-dependent harmonic
excitation spectrum which, strikingly, occurs in the Coulomb blockade regime.
The quantized excitation energy corresponds to the scale expected for
longitudinal vibrations of the nanotube. The electronic transport processes are
identified as cotunnel-assisted sequential tunneling, resulting from
non-equilibrium occupation of the mechanical mode. They appear only above a
high-bias threshold at the scale of electronic nanotube excitations. We discuss
models for the pumping process that explain the enhancement of the
non-equilibrium occupation and show that it is connected to a subtle interplay
between electronic and vibrational degrees of freedom
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
- …