Experimental evidence of delocalized states in random dimer superlattices

We study the electronic properties of GaAs-AlGaAs superlattices with intentional correlated disorder by means of photoluminescence and vertical dc resistance. The results are compared to those obtained in ordered and uncorrelated disordered superlattices. We report the first experimental evidence that spatial correlations inhibit localization of states in disordered low-dimensional systems, as our previous theoretical calculations suggested, in contrast to the earlier belief that all eigenstates are localized.Comment: 4 pages, 5 figures. Physical Review Letters (in press

Electronic structure and vertical transport in random dimer GaAs-Al_xGa_(1-x)As superlattices

We report a systematic study of several GaAs-AlxGa1-xAs semiconductor superlattices grown by molecular-beam epitaxy specifically designed to explore the existence of extended states in random dimer superlattices. We have confirmed our previous results [V. Bellani et al., Phys. Rev. Lett. 82, 2159 (1999)] with much additional evidence that allows us to lay claim to a clear-cut experimental verification of the presence of extended states in random dimer superlattices due to the short-range correlations (dimers) that inhibit the localization effects of the disorder

Influence of cane girdling and plastic covering on leaf gas exchange, water potential and viticultural performance of table grape cv. Matilde

Canes of field-grown uncovered and covered (plastic film) table grapes, cv. Matilde, were girdled at veraison. Leaves of girdled vines displayed lower rates of transpiration on a leaf area basis and lower rates of CO2 uptake; stem and leaf water potentials were decreased. Both, covering and cane girdling stimulated vegetative growth and increased leaf area per vine. However, sugar accumulation in berries and fruit quality were not affected by cane girdling and were slightly reduced by covering. Therefore, harvesting dates were not advanced. Cane girdling appeared to influence carbohydrate partitioning by stimulating shoot growth at the expense of fruit production. It is concluded that the stage of rapid sugar accumulation was not yet reached by the time girdling took place. The development of a larger transpiring leaf surface area per vine is supposed to have lowered the vine water status

Validation of the Italian version of the Devaluation consumers' Scale and the Devaluation Consumers Families Scale

Objectives: This study aimed to assess the psychometric properties of the Italian versions of the Devaluation of Consumers Scale (DCS) and the Devaluation of Consumer Families Scale (DCFS), two short-scales examining public stigma towards people with mental disorders and their relatives. Methods: The scales were administered to 117 individuals with a clinical diagnosis of affective or non-affective psychoses (ICD 10 criteria F20-29, F30-33). Translation procedures were carried out according to accepted standards. Internal reliability was assessed using Cronbach's alpha coefficient. Convergent validity was evaluated in terms of correlation with the Global Functioning Scale (GAF) and with the Questionnaire on Users' Opinions (QUO). Known-group validity was assessed comparing patients at first-episode of psychosis and patients with a history of psychosis of at least 3 years (long-term psychosis). Results: The overall Cronbach's alpha value was 0.85 for DCS and 0.81 for DCFS; subscales' alpha values ranged from 0.80 to 0.55 for DCS, and from 0.68 to 0.55 for DCFS. Negative correlations were found between the Italian DCS and the DCFS total score and the QUO affective problems (DCS -0.33; DCFS -0.235) and social distance subscales (DCS -0.290; DCFS -0.356). Moreover, the GAF positively correlated with some of the DCS and DCFS subscales. Patients with long-term psychosis had higher scores in most DCS and DCFS subscales. Conclusion: The Italian translation of DCF and DCFS showed good internal consistency, known-group validity, and convergent validity. These psychometric properties support their application in routine clinical practice in Italy as well as their use in international studies

Enabling Self-Powered Autonomous Wireless Sensors with New-Generation I2C-RFID Chips

A self-powered autonomous RFID device with sensing and computing capabilities is presented in this paper. Powered by an RF energy-harvesting circuit enhanced by a DC-DC voltage booster in silicon-on-insulator (SOI) technology, the device relies on a microcontroller and a new generation I2C-RFID chip to wirelessly deliver sensor data to standard RFID EPC Class-1 Generation-2 (Gen2) readers. When the RF power received from the interrogating reader is -14 dBm or higher, the device, fabricated on an FR4 substrate using low-cost discrete components, is able to produce 2.4-V DC voltage to power its circuitry. The experimental results demonstrate the effectiveness of the device to perform reliable sensor data transmissions up to 5 meters in fully-passive mode. To the best of our knowledge, this represents the longest read range ever reported for passive UHF RFID sensors compliant with the EPC Gen2 standard

04/15/1985 - Weekly Preview Review

Conventional RFID readers combine transmission (to the tag) and reception (from the tag) functions in a single physical device. In this paper we discuss the design and potential applications of a receive-only device, called "RFID listener", that decodes the signals from both the tag and the reader. This enables augmented RFID systems where one transmitter coexists with multiple listeners offering reception redundancy and diversity. We present a Software-Defined Radio (SDR) implementation of an RFID listener compliant with Gen2 standard, which can serve as a research tool for experimenting "on air" novel augmented RFID systems. Moreover, our listener can be used as a flexible and cheap protocol analyzer for conventional reader/tag systems. We present a test-bed setting where our listener and a conventional SDR reader are used in conjunction to measure separately the maximum downlink and uplink range. © 2011 IEEE

Orchard floor management affects tree functionality, productivity and water consumption of a late ripening peach orchard under semi-arid conditions

Semi-arid conditions are favorable for the cultivation of late ripening peach cultivars; however, seasonal water scarcity and reduction in soil biological fertility, heightened by improper soil management, are jeopardizing this important sector. In the present two-year study, four soil managements were compared on a late ripening peach orchard: (i) completely tilled (control); (ii) mulched with reusable reflective plastic film; (iii) mulching with a Leguminosae cover-crop flattened after peach fruit set; (iv) completely tilled, supplying the water volumes of the plastic mulched treatment, supposed to be lower than the control. Comparison was performed for soil features, water use, tree functionality, fruit growth, fruit quality, yield and water productivity. Even receiving about 50% of the regular irrigation, reusable reflective mulching reduced water loss and soil carbon over mineralization, not affecting (sometimes increasing) net carbon assimilation, yield, and fruit size and increasing water productivity. The flattening technique should be refined in the last part of the season as in hot and dry areas with clay soils and low organic matter, soil cracking increased water evaporation predisposing the orchard at water stress. The development and implementation of appropriate soil management strategies could be pivotal for making peach production economically and environmentally sustainable

Wireless resonant energy link for pulse generators implanted in the chest

This study investigates the feasibility of using the MedRadio band for wirelessly transmitting power to a rechargeable medical device implanted in the chest. In particular, a wireless energy link operating at 403 MHz and based on an inductive coupling between two planar resonators is considered, and its performance is assessed through simulations and experimental tests. Results show that a maximum value of the measured power transfer efficiency of ~23% is achieved. Furthermore, the possibility of using the link for recharging a lithium-ion battery of a pulse generator implanted in the chest at a depth of 5 mm is discussed, and the compliance with safety regulations is verified. Reported results demonstrate that the proposed link can be used to charge a lithium-ion battery with a capacity up to 7.2 mAh, while inducing a peak of the specific absorption rate averaged over 1 g of tissue < 1.6 W/kg