Engineering interband tunneling in nanowires with diamond cubic or zincblende crystalline structure based on atomistic modeling

We present an investigation in the device parameter space of band-to-band tunneling in nanowires with a diamond cubic or zincblende crystalline structure. Results are obtained from quantum transport simulations based on Non-Equilibrium Green's functions with a tight-binding atomistic Hamiltonian. Interband tunneling is extremely sensitive to the longitudinal electric field, to the nanowire cross section, through the gap, and to the material. We have derived an approximate analytical expression for the transmission probability based on WKB theory and on a proper choice of the effective interband tunneling mass, which shows good agreement with results from atomistic quantum simulation.Comment: 4 pages, 3 figures. Final version, published in IEEE Trans. Nanotechnol. It differs from the previous arXiv version for the title and for some changes in the text and in the reference

A transition towards sustainable food systems in Europe

A growing number of voices – among others the European Economic and Social Committee (EESC, 2017) - have highlighted the need to change the overarching infrastructure of food-related policies. They claim that the European Union does not have a food policy . For example, the General Food Law addresses food safety issues, but not nutrition. Regulations aimed at reducing the environmental impacts of food production are not built in connection with how food is consumed. There are regulations that encourage production systems to improve product quality, but the link to sustainability is not clear. There are rules that regulate information and communication to consumers, but a reference to sustainability is missing. Common Agricultural Policy grants subsidies to 'green' production processes, but most of them concern primarily production actors. Distribution of financial resources over these instruments is largely disproportionate. Often these payments are not linked to clear outcomes and impacts. How could a food policy contribute to shaping sustainable food systems in Europe? It is time for policy makers, academics, and civil society to take a step back and reflect upon appropriate policies infrastructures for transition toward food sustainability. This challenge implies a pervasive process that addresses in a consistent and coherent way the multidimensionality of food – environmental, social, economic, health, ethical and resilience implications - and takes into consideration the reciprocal influences between production, distribution and consumption and their links with broader socio-ecological and socio-technical systems. This process should reorganize food-related policy instruments around societal goals and put in place the necessary instruments to enable the social and institutional change, overcoming barriers. This report proposes a conceptual framework and carries out an assessment of the existing policy infrastructure with the purpose of suggesting points of entry for policy-led transition towards food sustainability in Europe. The system perspective adopted allows us to apply one of the key principles of sustainable development as well as sustainable consumption and implies that policies aiming at sustainability should address consumption issues as well as production patterns. The challenge for a new policy approach is to put in place coordinated policy tools that can affect directly or indirectly this process of alignment, linking together self-responsibility with freedom to act. Rather than pursuing an ambitious program of redesign of the agricultural policy into a broader food policy, we suggest a ‘bottom up’ process of construction of a food policy mix around strategic goals aimed at the integration and coherence between policies, together with the reorganization of existing tools and the introduction of new tools to fill existing gaps. The introduction of strategic tools - such as the EU Sustainable Food Assessment and Action Plan, proposed by the EESC (2017) at the EU level, or urban food strategies at the local level - can contribute to develop new representations of the food system, update policy objectives, verify the adequacy of existing policy instruments with respect to new objectives, identify missing policy instruments and mobilize all stakeholders to build a coherent set of policies. This report lays down some criteria on which this process should be activated

On the Feasibility of Overshadow Enlargement Attack on IEEE 802.15.4a Distance Bounding

Distance-bounding protocols are able to measure a secure upper bound to the distance between two devices. They are designed to resist to reduction attacks, whose objective is reducing the measured distance. In this paper we focus on the opposite problem, the enlargement attack, which is aimed at enlarging the measured distance. We analyze the feasibility of enlargement attacks through overshadow strategies on 802.15.4a UWB distance-bounding protocols. We show that the overshadow strategies, generally considered feasible by the existing literature, are actually difficult to carry out. Depending on the delay introduced by the adversary, there are cases in which they have no effect or their effect is not controllable

The energy sensor AMPK regulates Hedgehog signaling in human cells through a unique Gli1 metabolic checkpoint

Hedgehog signaling controls proliferation of cerebellar granule cell precursors (GCPs) and its aberrant activation is a leading cause of Medulloblastoma, the most frequent pediatric brain tumor. We show here that the energy sensor AMPK inhibits Hh signaling by phosphorylating a single residue of human Gli1 that is not conserved in other species.Studies with selective agonists and genetic deletion have revealed that AMPK activation inhibits canonical Hh signaling in human, but not in mouse cells. Indeed we show that AMPK phosphorylates Gli1 at the unique residue Ser408, which is conserved only in primates but not in other species. Once phosphorylated, Gli1 is targeted for proteasomal degradation. Notably, we show that selective AMPK activation inhibits Gli1-driven proliferation and that this effect is linked to Ser408 phosphorylation, which represents a key metabolic checkpoint for Hh signaling.Collectively, this data unveil a novel mechanism of inhibition of Gli1 function, which is exclusive for human cells and may be exploited for the treatment of Medulloblastoma or other Gli1 driven tumors

Mitogen-activated kinase kinase kinase 1 inhibits hedgehog signaling and medulloblastoma growth through GLI1 phosphorylation

The aberrant activation of hedgehog (HH) signaling is a leading cause of the development of medulloblastoma, a pediatric tumor of the cerebellum. The FDA‑approved HH inhibitor, Vismodegib, which targets the transmembrane transducer SMO, has shown limited efficacy in patients with medulloblastoma, due to compensatory mechanisms that maintain an active HH‑GLI signaling status. Thus, the identification of novel actionable mechanisms, directly affecting the activity of the HH‑regulated GLI transcription factors is an important goal for these malignancies. In this study, using gene expression and reporter assays, combined with biochemical and cellular analyses, we demonstrate that mitogen‑activated kinase kinase kinase 1 (MEKK1), the most upstream kinase of the mitogen‑activated protein kinase (MAPK) phosphorylation modules, suppresses HH signaling by associating and phosphorylating GLI1, the most potent HH‑regulated transcription factor. Phosphorylation occurred at multiple residues in the C‑terminal region of GLI1 and was followed by an increased association with the cytoplasmic proteins 14‑3‑3. Of note, the enforced expression of MEKK1 or the exposure of medulloblastoma cells to the MEKK1 activator, Nocodazole, resulted in a marked inhibitory effect on GLI1 activity and tumor cell proliferation and viability. Taken together, the results of this study shed light on a novel regulatory mechanism of HH signaling, with potentially relevant implications in cancer therapy

Use of UAVs and deep learning for beach litter monitoring

Stranded beach litter is a ubiquitous issue. Manual monitoring and retrieval can be cost and labour intensive. Therefore, automatic litter monitoring and retrieval is an essential mitigation strategy. In this paper, we present important foundational blocks that can be expanded into an autonomous monitoring-and-retrieval pipeline based on drone surveys and object detection using deep learning. Drone footage collected on the islands of Malta and Gozo in Sicily (Italy) and the Red Sea coast was combined with publicly available litter datasets and used to train an object detection algorithm (YOLOv5) to detect litter objects in footage recorded during drone surveys. Across all classes of litter objects, the 50%–95% mean average precision (mAP50-95) was 0.252, with the performance on single well-represented classes reaching up to 0.674. We also present an approach to geolocate objects detected by the algorithm, assigning latitude and longitude coordinates to each detection. In combination with beach morphology information derived from digital elevation models (DEMs) for path finding and identifying inaccessible areas for an autonomous litter retrieval robot, this research provides important building blocks for an automated monitoring-and-retrieval pipeline.peer-reviewe