Millimeter wave carbon nanotube gas sensor

This Letter reports experimental observations regarding the significant changes in the transmission modulus and phase of the propagating microwave signals up to 110 GHz in a micromachined coplanar waveguide supported on a dielectric membrane with a thickness of 1.4 m filled with a mixture of carbon nanotubes when exposed to nitrogen gas. These large shifts of amplitude and phase of microwave signals due to gas absorption represent the experimental basis on which a miniature wireless gas sensor could be implemented

Double-walled carbon nanotube-based polymer composites for electromagnetic protection.

In this paper, we present a microwave absorber based on carbon nanotubes (CNT) dispersed inside a BenzoCycloButenw (BCB) polymer. The high aspect ratio and remarkable conductive characteristics of CNT give rise to good absorbing properties for electromagnetic protecting in microelectronic devices with very low concentration. In this article, nanocomposites are prepared using a solution-mixing method and are then evaluated and modeled by means of coplanar test structures. First, CNT concentrations are quantified by image processing. The nanocomposites implemented with coplanar test waveguides are then characterized using a vector network analyzer from 40 MHz to 20 GHz. An algorithm is developed to calculate the propagation constant "γ" constant "α", and relative effective complex permittivity (εreff = εreff' - jεreff'') for each CNT concentration. The extracted effective parameters are verified using the electromagnetic FEM-based Ansoft’s® high frequency structure simulator (HFSS). Power absorption (PA) of 7 dB at 15 GHz is obtained with only 0.37 weight percent of CNT concentration in the polymer matrix. The resulting engineerable and controllable composite provides consequently a novel degree of freedom to design and optimize innovative microwave components

Experimental determination of microwave attenuation and electrical permittivity of double-walled carbon nanotubes

The attenuation and the electrical permittivity of the double-walled carbon nanotubes (DWCNTs) were determined in the frequency range of 1–65 GHz. A micromachined coplanar waveguide transmission line supported on a Si membrane with a thickness of 1.4 µm was filled with a mixture of DWCNTs. The propagation constants were then determined from the S parameter measurements. The DWCNTs mixture behaves like a dielectric in the range of 1–65 GHz with moderate losses and an abrupt change of the effective permittivity that is very useful for gas sensor detection. ©2006 American Institute of Physic

Demographic characteristics and projections of ethnic minorities and religious groups

Research findings report of DEMOGRAPHIC CHARACTERISTICS AND PROJECTIONS OF ETHNIC MINORITIES AND RELIGIOUS GROUPS project. A project in the ESRC Understanding Population Trends and Processes Programme, maintained by the ReStore repository and archived to NCRM Eprints 2022

Dexipm-Grapevine: a multicriteria assessment tool of the sustainability for grapevine farming systems

The development of innovative farming systems to reach new goals of agricultural sustainability needs new methods for efficiency assessment. DEXiPM-Grapevine© is a multicriteria assessment tool for overall sustainability of grapevine farming systems adapted from DEXiPM arable crops (Pelzer et al, 2012). DEXiPM-Grapevine© was implemented during the European PURE Project 2012-2015 (Integrated Pest Management (IPM) solutions in agriculture) in order to assess and compare various innovative grapevine systems. This model includes 65 basic attributes describing the cropping system, which are then combined into 97 aggregated attributes, designed to assess the economic, social and environmental performances. This model is based on expert knowledge and agricultural surveys, to define thresholds of classes for each attribute and the weighting of the aggregations. A guide helps users to adjust these parameter specific features due to local context. We tested DEXiPM-Grapevine© on innovative grapevine systems, designed with low pesticides use, and experimented at field scale in the French EcoViti Network. We made bothex ante and ex post analyses of experimented systems in order to sort them and to adjust their strategies. Three main strategies ofpesticide reduction are explored: (i) IPM, (ii) alternative products, organic and biocontrol approach, (iii) pesticide-free cropping systems based on new grapevine mildew resistant varieties. Seven prototypes are tested on INRA experimental farms in Angers(Loire Valley, center of France), Bordeaux (Atlantic region), and Montpellier (Mediterranean region). The first DEXiPMGrapevine© assessments show a high environmental performance of innovative biocontrol strategies, and new resistant varieties.However, IPM strategies have the best overall sustainability with better economic and social assessments. DEXiPM-Grapevine©supports the analysis of performances and helps to identify the strengths/weaknesses of the tested prototypes. This tool can be used for ex ante assessment to guide the designing of cropping systems. It can also enable to re-adjust the prototypes after fieldexperimentations. A third use for farmers' advisors is to help producers to modify their farming systems to enhance the sustainability of their farm

The success rate of online illicit drug transactions during a global pandemic

Background and Aims In the months following the onset of the COVID-19 pandemic, the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA; 2020) observed an increased use of cryptomarkets, which led them to question whether cryptomarkets constituted a more convenient channel via which to distribute illicit drugs without any in-person contact. However, as more countries' borders closed, the likelihood is that cryptomarkets have been negatively impacted. We aim to measure and understand the success rate of transactions on cryptomarkets during the ongoing COVID-19 pandemic, through recourse to self-reported data that documents the outcome of cryptomarket transactions. Methods To collect self-reported data on cryptomarket transactions, we launched a platform where participants can enter information about their prior activities on cryptomarkets. The sample consists of 591 valid self-reports that were received between January 1st, 2020 and August 21st, 2020. Results The number of unsuccessful transactions increased concurrently with the global spread of the pandemic. Both the international and inter-continental nature of the transactions and the severity of the crisis in the vendor's country are significantly associated with delivery failure. Conclusions Drug cryptomarkets may have been disrupted due to the pandemic. The results lead to two opposing explanations for unsuccessful transactions. One explanation for the lower success rate is the inability of drug dealers to deliver on past promises that were made in good faith, while the second points towards opportunistic and abusive behaviour by drug dealers

The influence of stress hormones and aggression on cooperative behaviour in subordinate meerkats

In cooperative breeders, aggression from dominant breeders directed at subordinates may raise subordinate stress hormone (glucocorticoid) concentrations. This may benefit dominants by suppressing subordinate reproduction but it is uncertain whether aggression from dominants can elevate subordinate cooperative behaviour, or how resulting changes in subordinate glucocorticoid concentrations affect their cooperative behaviour. We show here that the effects of manipulating glucocorticoid concentrations in wild meerkats (Suricata suricatta) on cooperative behaviour varied between cooperative activities as well as between the sexes. Subordinates of both sexes treated with a glucocorticoid receptor antagonist (mifepristone) exhibited significantly more pup protection behaviour (babysitting) compared to those treated with glucocorticoids (cortisol) or controls. Females treated with mifepristone had a higher probability of exhibiting pup food provisioning (pup-feeding) compared to those treated with cortisol. In males, there were no treatment effects on the probability of pup-feeding, but those treated with cortisol gave a higher proportion of the food they found to pups than those treated with mifepristone. Using 19 years of behavioural data, we also show that dominant females did not increase the frequency with which they directed aggression at subordinates at times when the need for assistance was highest. Our results suggest that it is unlikely that dominant females manipulate the cooperative behaviour of subordinates through the effects of aggression on their glucocorticoid levels and that the function of aggression directed at subordinates is probably to reduce the probability they will breed

Assessing dominance hierarchies: validation and advantages of progressive evaluation with Elo-rating

Highlights ► Elo-rating generates reliable dominance hierarchies and circumvents drawbacks of established ranking methods. ► It allows visualizing dominance relationships and the detection of rank dynamics. ► An index to objectively assess the stability of a dominance hierarchy is proposed