Shot Noise in Linear Macroscopic Resistors

We report on a direct experimental evidence of shot noise in a linear macroscopic resistor. The origin of the shot noise comes from the fluctuation of the total number of charge carriers inside the resistor associated with their diffusive motion under the condition that the dielectric relaxation time becomes longer than the dynamic transit time. Present results show that neither potential barriers nor the absence of inelastic scattering are necessary to observe shot noise in electronic devices.Comment: 10 pages, 5 figure

Modelization of Thermal Fluctuations in G Protein-Coupled Receptors

We simulate the electrical properties of a device realized by a G protein coupled receptor (GPCR), embedded in its membrane and in contact with two metallic electrodes through which an external voltage is applied. To this purpose, recently, we have proposed a model based on a coarse graining description, which describes the protein as a network of elementary impedances. The network is built from the knowledge of the positions of the C-alpha atoms of the amino acids, which represent the nodes of the network. Since the elementary impedances are taken depending of the inter-nodes distance, the conformational change of the receptor induced by the capture of the ligand results in a variation of the network impedance. On the other hand, the fluctuations of the atomic positions due to thermal motion imply an impedance noise, whose level is crucial to the purpose of an electrical detection of the ligand capture by the GPCR. Here, in particular, we address this issue by presenting a computational study of the impedance noise due to thermal fluctuations of the atomic positions within a rhodopsin molecule. In our model, the C-alpha atoms are treated as independent, isotropic, harmonic oscillators, with amplitude depending on the temperature and on the position within the protein (alpha-helix or loop). The relative fluctuation of the impedance is then calculated for different temperatures.Comment: 5 pages, 2 figures, Proceeding of the 18-th International Conference on Fluctuations and Noise, 19-23 September 2005, Salamanca, Spain -minor proofreadings

Geomorphological evolution of the western piedmont of Cumbres Calchaquíes (Tucumán Province, NW Argentina)

The aim of this paper is to present a detailed geomorphological map of the western piedmont of Cumbres Calchaquíes (Tucumán Province, NW Argentina) bounded by the Amaicha River to the south and the administrative border with Salta Province to the north. It contains information about geomorphological units, their relative ages, and morphogenetic processes. The main map shows the presence of seven aggradation stages separated by incision phases. The first three stages (St1, St2, and St3) were modeled on a thick accumulation located in the upper piedmont from the Late Pliocene and Early Pleistocene. Intermediate stages (St4 and St5) are alluvial fans and pediments with less thickness and gradient. They cover the Early Pleistocene (St4) and the Late Pleistocene-Middle Holocene (St5). Finally, stages St6 and St7 are from the Upper Holocene

A New Lithospheric Density and Magnetic Susceptibility Model of Iran, Starting From High‐Resolution Seismic Tomography

We propose a new model for the crust and upper mantle in Iran by joint inversion of gravity and magnetic fields, constrained with a seismic tomography model. We then calculate shear modulus from the Vs velocities and densities. The crust and mantle tomography model is first converted to a density cube through empirical and petrological velocity-density relations. The starting susceptibility is assigned to a two-layer homogeneous model, above a heat flow-derived Curie depth. Considering the uncertainties in the density-velocity relations, and the starting layered susceptibility variation, we refine the model by a constrained inversion of the gravity and magnetic fields with a Bayesian approach, producing the final 3D density and susceptibility model. The area is tectonically active with high seismicity and active faulting which are regulated by the crustal density and rigidity variations. Higher rigidity matches lower seismicity and extended deserts and basins, suggesting the control of their development. The Neo-Tethys suture, extending similar to 1,500 km long, as well as the Paleo-Tethys suture match crustal scale density variations, defining characteristics of the lighter Arabian plate and denser Eurasian crust. The South Caspian Basin is enigmatic, due to focusing on the seismicity along all its borders, but with relatively low average rigidity, which is contrary to what is observed for Iran, where the reduced rigidity correlates with higher seismicity. The 3D density model will be useful for numerical geodynamic models and obtaining geologic inferences from the crustal-scale units. The inversion of potential fields may produce inconsistent results, since there are always multiple models that resolve the anomalies, and the use of other geophysical data sets is necessary. To resolve the problem, we extract information from a high-resolution seismic tomography. With seismic velocities and defining the different layers of the model, using data available in the literature, we realize an a-priori model, on which we perform a Bayesian joint gravity and magnetic inversion, to obtain a final 3D model of the Iranian lithosphere, with a detailed distribution of densities and susceptibilities. With density and velocity values, we also calculate the rigidity of the area. We then compare the models obtained, with geological and tectonic information of the area, observing how density and susceptibility distribution reproduce the position of the magmatic outcrops and the principal tectonic lineaments, indicating the position of the Neo-Tethyan and Paleo-Tethyan sutures. Also, the rigidity model is consistent with the seismicity distribution of the area. 3D Bayesian joint inversion builds a reliable model of the lithosphere in the Iranian collision belt, useful for rheological calculationsMost of the magmatic and tectonic features can be followed by density variations in the crust, partly extending to the lower crustJointly with the seismic Vs tomography, rigidity is obtained which explains the inhomogeneous distribution of seismicity in the are

Design of an air-flow microchamber for microparticles detec

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.A novel device, able to funnel a suspension of micrometric particles in air into a microchamber equipped with a capacitive sensor, has been designed for the detection and characterization of particulate matter (PM) in air. Numerical simulations have been performed to predict the trajectory of the microparticles through the PDMS microchamber where the sensor is located. The feasibility of detecting single PM10 particles has been demonstrated by our experiments, where sequences of single industrial talc particles (average diameter of 8 μm) have been detected and counted by a capacitive sensor. Our results indicate that radical miniaturization of air quality monitors is possible and, therefore, pervasive monitoring of air pollution will be soon feasible

Lipoprotein(a) Lowering-From Lipoprotein Apheresis to Antisense Oligonucleotide Approach

It is well-known that elevated lipoprotein(a)-Lp(a)-levels are associated with a higher risk of cardiovascular (CV) mortality and all-cause mortality, although a standard pharmacotherapeutic approach is still undefined for patients with high CV risk dependent on hyperlipoproteinemia(a). Combined with high Lp(a) levels, familial hypercholesterolemia (FH) leads to a greater CVD risk. In suspected FH patients, the proportion of cases explained by a rise of Lp(a) levels ranges between 5% and 20%. In the absence of a specific pharmacological approach able to lower Lp(a) to the extent required to achieve CV benefits, the most effective strategy today is lipoprotein apheresis (LA). Although limited, a clear effect on Lp(a) is exerted by PCSK9 antagonists, with apparently different mechanisms when given with statins (raised catabolism) or as monotherapy (reduced production). In the era of RNA-based therapies, a new dawn is represented by the use of antisense oligonucleotides APO(a)Lrx, able to reduce Lp(a) from 35% to over 80%, with generally modest injection site reactions. The improved knowledge of Lp(a) atherogenicity and possible prevention will be of benefit for patients with residual CV risk remaining after the most effective available lipid-lowering agents

6-channel CMOS-based instrument for optical absorption spectroscopy and chemical identification

A multichannel portable instrument for on-chip optical absorption spectroscopy is presented. The system can house photonic chips having up to 6 sensing sites operating in parallel, allowing real-time simultaneous detection of multiple chemicals. A 6-channel CMOS lock-in front-end performs the amplification and demodulation of the signals from the integrated light detectors, while an FPGA is chosen for signal acquisition and analysis. A digital real-time ratiometric processing cancels out the effect of laser power fluctuations to achieve high sensitivity in monitoring the presence of the analytes, as demonstrated with the detection of an acetone sample. Compact size for portability, real-time parallel detection and flexible FPGA processing make this system suitable for environmental investigations on many different pollutants, both in the near- and mid-infrared wavelength range

Deployment and design of multiantenna solutions for fixed WiMAX systems

WiMax has already attracted the attention of operators and manifacturing industries for its promise of large throughput and coverage in broadband wireless access. However, towards the goal of an efficient deployment of this technology, a thorough analysis of its performance in presence of frequency reuse under realistic traffic conditions is mandatory. In particular, an important performance limiting factor is the inter-cell interference, which has strong non-stationary features. This paper investigates the deployment of multi-antenna base stations and the related design of signal processing algorithms for interference mitigation, for the uplink of IEEE 802.16-2004 systems. Extensive numerical results for realistic interference models show the advantages of the proposed multi-antenna system