The Neutrino Option

The minimal seesaw scenario can radiatively generate the Higgs potential to induce electroweak symmetry breaking while supplying an origin of the Higgs vacuum expectation value from an underlying Majorana scale. If the Higgs potential and (derived) electroweak scale have this origin, the heavy $\rm SU(3) \times SU(2) \times U(1)_Y$ singlet states are expected to reside at $m_N \sim 10-500 \, {\rm PeV}$ for couplings $|\omega| \sim 10^{-4.5}-10^{-6}$ between the Majorana sector and the Standard Model. In this framework, the challenge of the electroweak scale hierarchy problem is replaced with a need to generate or accommodate PeV Majorana mass scales in ultraviolet models; the usual hierarchy problem is absent as the electroweak scale is not a fundamental scale.Comment: 5 pages, 5 figures, one radiative potential. Updated version consistent with the one accepted for publication in PRL (title changed in the journal

Effects of fullerene on lipid bilayers displaying different liquid ordering: a coarse-grained molecular dynamics study

Background The toxic effects and environmental impact of nanomaterials, and in particular of Fullerene particles, are matters of serious concern. It has been reported that fullerene molecules enter the cell membrane and occupy its hydrophobic region. Understanding the effects of Carbon-based nanoparticles on biological membranes is therefore of critical importance to determine their exposure risks. Methods We report on a systematic coarse-grained molecular dynamics study of the interaction of fullerene molecules with simple model cell membranes. We have analyzed bilayers consisting of lipid species with different degrees of unsaturation and a variety of cholesterol fractions. Addition of fullerene particles to phase-segregated ternary membranes is also investigated in the context of the lipid raft model for the organization of the cell membrane. Results Fullerene addition to lipid membranes modifies their structural properties like thickness, area and internal ordering of the lipid species, as well as dynamical aspects such as molecular diffusion and cholesterol flip-flop. Interestingly, we show that phase-segregating ternary lipid membranes accumulate fullerene molecules preferentially in the liquid-disordered domains promoting phase-segregation and domain alignment across the membrane. Conclusions Lipid membrane internal ordering determines the behavior and distribution of fullerene particle, and this, in turn, determines the influence of fullerene on the membrane. Lipid membranes are good solvents of fullerene molecules, and in particular those with low internal ordering. General Significance Preference of fullerene molecules to be dissolved in the more disordered hydrophobic regions of a lipid bilayer and the consequent alteration of its phase behavior may have important consequences on the activity of biological cell membranes and on the bioconcentration of fullerene in living organisms.Peer ReviewedPostprint (author's final draft

Ultrasensitive interferometric on-chip microscopy of transparent objects

Light microscopes can detect objects through several physical processes, such as scattering, absorption, and reflection. In transparent objects, these mechanisms are often too weak, and interference effects are more suitable to observe the tiny refractive index variations that produce phase shifts. We propose an on-chip microscope design that exploits birefringence in an unconventional geometry. It makes use of two sheared and quasi-overlapped illuminating beams experiencing relative phase shifts when going through the object, and a complementary metal-oxide-semiconductor image sensor array to record the resulting interference pattern. Unlike conventional microscopes, the beams are unfocused, leading to a very large field of view (20 mm(2)) and detection volume (more than 0.5 cm(3)), at the expense of lateral resolution. The high axial sensitivity (<1 nm) achieved using a novel phase-shifting interferometric operation makes the proposed device ideal for examining transparent substrates and reading microarrays of biomarkers. This is demonstrated by detecting nanometer-thick surface modulations on glass and single and double protein layers.Peer ReviewedPostprint (published version

Application of Wireless Sensor and Actuator Networks to Achieve Intelligent Microgrids: A Promising Approach towards a Global Smart Grid Deployment

Smart Grids (SGs) constitute the evolution of the traditional electrical grid towards a new paradigm, which should increase the reliability, the security and, at the same time, reduce the costs of energy generation, distribution and consumption. Electrical microgrids (MGs) can be considered the first stage of this evolution of the grid, because of the intelligent management techniques that must be applied to assure their correct operation. To accomplish this task, sensors and actuators will be necessary, along with wireless communication technologies to transmit the measured data and the command messages. Wireless Sensor and Actuator Networks (WSANs) are therefore a promising solution to achieve an intelligent management of MGs and, by extension, the SG. In this frame, this paper surveys several aspects concerning the application of WSANs to manage MGs and the electrical grid, as well as the communication protocols that could be applied. The main concerns regarding the SG deployment are also presented, including future scenarios where the interoperability of different generation technologies must be assured

Detection, Characterization and Modeling of Localized Defects and Thermal Breakdown in Photovoltaic Panels from Thermal Images and IV Curves

In this work, a defective commercial module with a rounded IV characteristic is analyzed in detail to identify the sources of its malfunction. The analysis of the module includes thermography images taken under diverse conditions, the IV response of the module obtained without any shadow, and shadowing one cell at a time, as recommended by the IEC 61215 Standard. Additionally, a direct measurement of the IV characteristic and resistance of single cells in the panel has been conducted to verify the isolation between the p and n areas. In parallel, theoretical cell and module behaviors are presented. In this frame, simulations show how cell mismatch can be the explanation to the rounded IV output of the solar panel under study. From the thermal images of the module, several localized hot spots related to failing cells have been revealed. During the present study, thermal breakdown is seen before avalanche breakdown in one of the cells, evidencing a hot spot. Not many papers have dealt with this problem, whereas we believe it is important to analyze the relationship between thermal breakdown and hot spotting in order to prevent it in the future, since hot spots are the main defects related to degradation of modern modules

Energy-aware Cross-level Model for Wireless Sensor Networks

ISBN: 978-1-61208-744-3International audienceIn the design stage, Wireless Sensor Network developers generally need simulation tools to save both time and costs. These simulators require accurate models to precisely describe the network components and behaviours, such as energy consumption. Nevertheless, although the model has grown in complexity over last years, from layered-stack to cross-level, the energy aspects are not yet well implemented. In this paper, we suggest an energy-aware cross-level model for Wireless Sensor Networks. Our modelling approach allows for parameters that belong to different levels to interact with each other and to analyse their impact on energy consumption. To validate this approach, the energy-aware cross-level model for network radiofrequency activities is first provided. The results obtained using suggested scenarios are compared with those collected from a well-known simulator: NS2. Finally, the usefulness of our model in Wireless Sensor Network design process is demonstrated thanks to a case study aimed at comparing and selecting the most energy-efficient wireless link protocol

Improving Low Power Listening (LPL) Mechanism to Save Energy Consumption in WSN

As stated in the literature, Low Power Listening (LPL) duty cycle is one of the most common energy conservation solution for WSN. By using channel check mechanism, the purpose of LPL solutions is to reduce the energy consumption of the listening phase. In this paper, we propose to study the performances and limitations of this kind of solutions. Therefore, we deploy a ContikiMAC LPL on both real and simulated WSN platform to demonstrate the impact of LPL on the energy consumptions of the node radio and microcontroller but also on the application Quality of Service. Based on the obtained results, shortcomings of LPL solutions are highlighted and potential improvements are discussed such as the use of multi-parameter dynamic duty cycle

Embedded Image Capture System for Liquid Monitoring in the Smart Chemical Industry

The work presented in this paper is carried out as a part of the design of a supervision system based on a visual wireless sensor network dedicated to the Smart Chemical Industry. Since the visual sensor nodes are battery powered, our objective is to reach a compromise between the energy consumption and the exploitability of the captured images. In this article, we are interested in how to highlight some important details of the image at the moment of its capture, a topic which has not yet been exhaustively covered in previous research works. As light is absorbed by materials through which it is passing, a correct image exploitability can be reached when applying the adequate light color. Thus, this paper studies the color light effects on the captured images. For that, one visual sensor node, based on Raspberry Pi and a camera, is designed to conduct experiments. In addition, a laboratory glass container including liquids is developed and used as an emulator of the real system.HYPERCOG H202