Effect of the experimental technique onto R dependence of ΔKth

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Stochastic Memory Devices for Security and Computing

With the widespread use of mobile computing and internet of things, secured communication and chip authentication have become extremely important. Hardware-based security concepts generally provide the best performance in terms of a good standard of security, low power consumption, and large-area density. In these concepts, the stochastic properties of nanoscale devices, such as the physical and geometrical variations of the process, are harnessed for true random number generators (TRNGs) and physical unclonable functions (PUFs). Emerging memory devices, such as resistive-switching memory (RRAM), phase-change memory (PCM), and spin-transfer torque magnetic memory (STT-MRAM), rely on a unique combination of physical mechanisms for transport and switching, thus appear to be an ideal source of entropy for TRNGs and PUFs. An overview of stochastic phenomena in memory devices and their use for developing security and computing primitives is provided. First, a broad classification of methods to generate true random numbers via the stochastic properties of nanoscale devices is presented. Then, practical implementations of stochastic TRNGs, such as hardware security and stochastic computing, are shown. Finally, future challenges to stochastic memory development are discussed

Supersonic investigation of two dimensional hypersonic exhaust nozzles

An experimental investigation was conducted in the NASA Lewis 10 x 10 ft supersonic Wind Tunnel to determine the performance characteristics of 2D hypersonic exhaust nozzles/afterbodies at low supersonic conditions. Generally, this type of application requires a single expansion ramp nozzle (SERN) that is highly integrated with the airframe of the hypersonic vehicle. At design conditions (hypersonic speeds), the nozzle generally exhibits acceptable performance. At off-design conditions (transonic to mid-supersonic speeds), nozzle performance of a fixed geometry configuration is generally poor. Various 2-D nozzle configurations were tested at off-design conditions from Mach 2.0 to 3.5. Performance data is presented at nozzle pressure ratios from 1 to 35. Jet exhaust was simulated with high-pressure air. To study performance of different geometries, nozzle configurations were varied by interchanging the following model parts: internal upstream contour, expansion ramp, sidewalls, and cowl

Photochemical Organocatalytic Regio- and Enantioselective Conjugate Addition of Allyl Groups to Enals

We report the first catalytic enantioselective conjugate addition of allyl groups to α,β-unsaturated aldehydes. The chemistry exploits the visible-light-excitation of chiral iminium ions to activate allyl silanes towards the formation of allylic radicals, which are then intercepted stereoselectively. The underlying radical mechanism of this process overcomes the poor regio- and chemoselectivity that traditionally affects the conjugate allylation of enals proceeding via polar pathways. We also demonstrate how this organocatalytic strategy could selectively install a valuable prenyl fragment at the β-carbon of enals

Humans and viticulture in Sardinia: the history and social relations as signs of identity of the wine-growing area.

The premise of this paper is that viticulture is an expression of history and social relations. In this sense, we embrace a post-modern vision of development that characterized both economic and cultural geography and agricultural economics. Such an approach does consider culture as an element of mediation between humans and the nature, placing it at the heart of the wine-growing territory. So history and social relations have influenced the today spatial densification by types of grape and the persistence, the reduction and/or disappearance of vines\u2019 cultivations due to the different level of integration between humans and wine territories in the Italian region of Sardinia. In this region, there are selected areas where winegrowers have been forced to grub vineyards up, depleting the regional viticultural heritage, others\u2013\u2013within which the fabric of the system of social relationships were denser\u2013\u2013and where we saw a real rush to purchase of replanting rights for the expansion of the production surface for the increasing of production. The aim of this paper is to highlight the role of history and social relations in the determination of the structure of the regional viticulture through the identification and analysis of diverse case studies

The use of biorefinery by-products and natural detritus as feed sources for Oysters (Crassostrea gigas) juveniles

New research is currently underway to explore the potential of macroalgae for the production of biofuels. Marine biofuels in general and macroalgae in particular, offer a number of advantages over terrestrial biofuels including reduced competition for freshwater resources and for land use. Sugars can be extracted from macroalgae and processed into biofuels by anaerobic digestion and fermentation. This process generates significant waste biomass, which, if used, could improve the economic sustainability of the biorefinery sector. Bivalves’ aquaculture relies heavily on the production of unicellular algae to feed juvenile individuals and this can represent a bottleneck for the bivalve industry especially in locations where sunlight is limited. Previous research explored the use of macroalgae derived digestate as alternative or integrative feed for juvenile bivalves, exploiting the notion that organic particulate matter (detritus) is an integral part of this animal class natural diet. The prospect of using waste products from the emerging biorefinery industry to solve a bottleneck for aquaculture businesses and, by so doing, improving profitability of both, is an exciting one. In this paper we describe the main nutritional profiles (Protein, Lipid, Carbohydrates and Fatty acids) of the tested diets and investigate the potential for the use of a biorefinery a by-product as replacement option for bivalves’ production, by benchmarking it against aquaculture industry standards (live microalgae and commercially available algae paste) and natural detritus constituted by farmed sea urchin digesta. Both the digestate and the natural detritus supported the survival and growth of bivalve spat, especially when used at 50% inclusion rate, over the course of 4-week preliminary trials. Data suggest that a synergistic effect of the nutritional profiles of the diets employed may underpin the observed results

Increased Expression of Autophagy-Related Genes in Alzheimer’s Disease—Type 2 Diabetes Mellitus Comorbidity Models in Cells

The association between Alzheimer’s disease (AD) and type 2 diabetes mellitus (T2DM) has been extensively demonstrated, but despite this, the pathophysiological mechanisms underlying it are still unknown. In previous work, we discovered a central role for the autophagy pathway in the common alterations observed between AD and T2DM. In this study, we further investigate the role of genes belonging to this pathway, measuring their mRNA expression and protein levels in 3xTg-AD transgenic mice, an animal model of AD. Moreover, primary mouse cortical neurons derived from this model and the human H4Swe cell line were used as cellular models of insulin resistance in AD brains. Hippocampal mRNA expression showed significantly different levels for Atg16L1, Atg16L2, GabarapL1, GabarapL2, and Sqstm1 genes at different ages of 3xTg-AD mice. Significantly elevated expression of Atg16L1, Atg16L2, and GabarapL1 was also observed in H4Swe cell cultures, in the presence of insulin resistance. Gene expression analysis confirmed that Atg16L1 was significantly increased in cultures from transgenic mice when insulin resistance was induced. Taken together, these results emphasise the association of the autophagy pathway in AD-T2DM co-morbidity, providing new evidence about the pathophysiology of both diseases and their mutual interaction

First results from an aging test of a prototype RPC for the LHCb Muon System

Recent results of an aging test performed at the CERN Gamma Irradiation Facility on a single--gap RPC prototype developed for the LHCb Muon System are presented. The results are based on an accumulated charge of about 0.45 C/cm$^2$, corresponding to about 4 years of LHCb running at the highest background rate. The performance of the chamber has been studied under several photon flux values exploiting a muon beam. A degradation of the rate capability above 1 kHz/cm$^2$ is observed, which can be correlated to a sizeable increase of resistivity of the chamber plates. An increase of the chamber dark current is also observed. The chamber performance is found to fulfill the LHCb operation requirements.Comment: 6 pages, 9 figures, presented at the International Workshop on Aging Phenomena in Gaseous Detectors'', DESY-Hamburg (Germany), October 200

Preliminary results of an aging test of RPC chambers for the LHCb Muon System

The preliminary results of an aging test performed at the CERN Gamma Irradiation Facility on a single--gap RPC prototype developed for the LHCb Muon System are presented. The results are based on an accumulated charge density of 0.42 C/cm^2, corresponding to about 4 years of LHCb running at the highest background rate. We observe a rise in the dark current and noise measured with source off. The current drawn with source on steadily decreased, possibly indicating an increase of resistivity of the chamber plates. The performance of the chamber, studied with a muon beam under several photon flux values, is found to still fulfill the LHCb operation requirements.Comment: 4 pages, 6 figures, presented at RPC2001, VIth Workshop on Resistive Plate Chambers and Related Detectors, November 26-27 2001, Coimbra, Portuga

Experiments on crack propagation and threshold at defects in press-fits of railway axles

Fatigue strength under fretting fatigue is one of the open problems in the area of fatigue. In the case of railway wheel-axle press-fits, there are no records of recent failures because design rules are today based on making the shape of geometrical transitions the most stressed point. However, it is important to analyze correctly the acceptability of defects and micro-cracks at press-fits. In this paper, after a preliminary presentation of the results obtained by a new criterion for predicting the non-propagation of cracks under rolling contact fatigue conditions, a new series of experiments on full-scale axle press-fits containing artificial defects is presented and discussed. Results show the modified Dang Van criterion is adequate for describing the development of natural cracks and cracks from artificial defects. The latter, characterized by a depth of 250 350 m, are competitors of fretting cracks naturally developed from surface scars and surface damage