1,513 research outputs found
Quantum Noise Measurement of a Carbon Nanotube Quantum Dot in the Kondo Regime
The current emission noise of a carbon nanotube quantum dot in the Kondo
regime is measured at frequencies of the order or higher than the
frequency associated with the Kondo effect , with the Kondo
temperature. The carbon nanotube is coupled via an on-chip resonant circuit to
a quantum noise detector, a superconductor-insulator-superconductor junction.
We find for a Kondo effect related singularity at a
voltage bias , and a strong reduction of this singularity
for , in good agreement with theory. Our experiment
constitutes a new original tool for the investigation of the non-equilibrium
dynamics of many-body phenomena in nanoscale devices.Comment: 6 pages, 4 figure
Spin orbit coupling at the level of a single electron
We utilize electron counting techniques to distinguish a spin conserving fast
tunneling process and a slower process involving spin flips in
AlGaAs/GaAs-based double quantum dots. By studying the dependence of the rates
on the interdot tunnel coupling of the two dots, we find that as many as 4% of
the tunneling events occur with a spin flip related to spin-orbit coupling in
GaAs. Our measurement has a fidelity of 99 % in terms of resolving whether a
tunneling event occurred with a spin flip or not
Variation in carbon footprint of milk due to management differences between Swedish dairy farms
To identify mitigation options to reduce greenhouse gas (GHG) emissions from milk production (i.e. the carbon footprint (CF) of milk), this study examined the variation in GHG emissions among dairy farms using data from previous CF studies on Swedish milk. Variation between farms in these production data, which were found to have a strong influence on milk CF were obtained from existing databases of e.g. 1051 dairy farms in Sweden in 2005. Monte Carlo analysis was used to analyse the impact of variations in seven important parameters on milk CF concerning milk yield (energy corrected milk (ECM) produced and delivered), feed dry matter intake (DMI), enteric methane emissions, N content in feed DMI, N-fertiliser rate and diesel used on farm. The largest between farm variation among the analysed production data were N-fertiliser rate (kg/ha) and diesel used (l/ha) on farm (coefficient of variation (CV) 31-38%). For the parameters concerning milk yield and feed DMI the CV was approx. 11 and 8%, respectively. The smallest variation in production data was found for N content in feed DMI. According to the Monte Carlo analysis, these variations in production data led to a variation in milk CF of between 0.94 and 1.33 kg CO2 equivalents (CO2e) per kg ECM, with an average value of 1.13 kg/CO2e kg ECM. We consider that this variation of ±17% that was found based on the used farm data would be even greater if all Swedish dairy farms were included, as the sample of farms in this study was not totally unbiased. The variation identified in milk CF indicates that a potential exists to reduce GHG emissions from milk production on both national and farm level through changes in management. As milk yield and feed DMI are two of the most influential parameters for milk CF, feed conversion efficiency (i.e. units ECM produced per unit DMI) can be used as a rough key performance indicator for predicting CF reductions. However, it must be borne in mind that feeds have different CF due to where and how they are produced
A case study on the application of the MSFD to Mediterranean coastal systems: the Po plume, as a transitional water system in the Northern Adriatic basin.
1 - In the frame of the Marine Strategy Framework Directive (MSFD) of the European Community, in
order to assess the Good Environmental Status (GES) of the marine coastal and estuarine waters,
the eutrophication descriptors include several aspects of the phytoplankton communities (such as
composition, abundance and biomass).
2 - Two oceanographic campaigns were carried out in the area off the Po River plume, where a highly
dynamic frontal zone separates an inshore and an offshore system. The coupling of size structure and
diagnostic pigments of phytoplankton communities in relation to different environmental contexts
are tested as an expedite and informative tool to assess water quality sensu MSFD.
3 - The Po plume creates a very dynamic frontal zone, resulting in strong trophic gradients within a
relatively small area.
4 - The spatio-temporal variability of salinity in coastal waters and in transitional waters plays a pivotal
role in structuring phytoplankton communities.
5 - The dynamics of forcing factors drive changes in cell-size structure, in the functional group
composition as well as a shift in size within the same functional group.
6 - The combination of phytoplankton size-structure and chemotaxonomic compositions is proposed
as an expedite tool for investigating, at the appropriate scales, the ecology of transitional water
systems
Acquatina Lagoon: a model ecosystem to study community patterns
Acquatina is a small lagoon ecosystem (0.45 km2) located on the Adriatic coast only 5 km north
of Lecce (Italy). The lagoon has a freshwater input in the northern part and a connection with
the sea at the south edge, being characterised by a latitudinal gradient of salinity and an internal
patchiness of habitats. Here, we have used the lagoons as a model to study the influence of
these sources of variation on the spatial distribution of macrobenthis and fish fauna, using both
taxonomic and on taxonomic descriptors. Results showed a non random distribution of both species and functional traits of macroinvertebrate
and fish fauna within the lagoon, despite the relatively small surface area. Salinity had an higher inflence than boItom habitat patchiness on both macroinvertebrates and fishes; moreover, spatial co-variance of the two guilds was observed both at the taxonomic and at the size level. As regards
fishes, these patterns were common to the dominant species (Atherina Boyeri) and to the rest of the fish guild.
Results emphasise that common non random distribution patterns are observed even in small lagoons and for different guilds, including vagile fauna, as fish are. It suggest the occurrence of high intra-specific and inter-specific divergence in lagoon ecosystem allowing resource use
optimisation through niche specialisation, available energy partitioning and individual energy budget adaptation
Dynamics of a small neutrally buoyant sphere in a fluid and targeting in Hamiltonian systems
We show that, even in the most favorable case, the motion of a small
spherical tracer suspended in a fluid of the same density may differ from the
corresponding motion of an ideal passive particle. We demonstrate furthermore
how its dynamics may be applied to target trajectories in Hamiltonian systems.Comment: See home page http://lec.ugr.es/~julya
Heat Shock Proteins Alterations in Rheumatoid Arthritis
Rheumatoid arthritis (RA) is a chronic inflammatory and autoimmune disease characterized by the attack of the immune system on the body’s healthy joint lining and degeneration of articular structures. This disease involves an increased release of inflammatory mediators in the affected joint that sensitize sensory neurons and create a positive feedback loop to further enhance their release. Among these mediators, the cytokines and neuropeptides are responsible for the crippling pain and the persistent neurogenic inflammation associated with RA. More importantly, specific proteins released either centrally or peripherally have been shown to play opposing roles in the pathogenesis of this disease: an inflammatory role that mediates and increases the severity of inflammatory response and/or an anti-inflammatory and protective role that modulates the process of inflammation. In this review, we will shed light on the neuroimmune function of different members of the heat shock protein (HSPs) family and the complex manifold actions that they exert during the course of RA. Specifically, we will focus our discussion on the duality in the mechanism of action of Hsp27, Hsp60, Hsp70, and Hsp90
Molecular Mechanisms Leading from Periodontal Disease to Cancer
Periodontitis is prevalent in half of the adult population and raises critical health concerns as it has been recently associated with an increased risk of cancer. While information about the topic remains somewhat scarce, a deeper understanding of the underlying mechanistic pathways promoting neoplasia in periodontitis patients is of fundamental importance. This manuscript presents the literature as well as a panel of tables and figures on the molecular mechanisms of Porphyromonas gingivalis and Fusobacterium nucleatum, two main oral pathogens in periodontitis pathology, involved in instigating tumorigenesis. We also present evidence for potential links between the RANKL–RANK signaling axis as well as circulating cytokines/leukocytes and carcinogenesis. Due to the nonconclusive data associating periodontitis and cancer reported in the case and cohort studies, we examine clinical trials relevant to the topic and summarize their outcome
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