With wide deployment of machine learning (ML)-based systems for a variety of applications including medical, military, automotive, genomic, multimedia, and social networking, there is great potential ...for damage from adversarial learning (AL) attacks. In this article, we provide a contemporary survey of AL, focused particularly on defenses against attacks on deep neural network classifiers. After introducing relevant terminology and the goals and range of possible knowledge of both attackers and defenders, we survey recent work on test-time evasion (TTE), data poisoning (DP), backdoor DP, and reverse engineering (RE) attacks and particularly defenses against the same. In so doing, we distinguish robust classification from anomaly detection (AD), unsupervised from supervised, and statistical hypothesis-based defenses from ones that do not have an explicit null (no attack) hypothesis. We also consider several scenarios for detecting backdoors. We provide a technical assessment for reviewed works, including identifying any issues/limitations, required hyperparameters, needed computational complexity, as well as the performance measures evaluated and the obtained quality. We then delve deeper, providing novel insights that challenge conventional AL wisdom and that target unresolved issues, including: robust classification versus AD as a defense strategy; the belief that attack success increases with attack strength, which ignores susceptibility to AD; small perturbations for TTE attacks: a fallacy or a requirement; validity of the universal assumption that a TTE attacker knows the ground-truth class for the example to be attacked; black, gray, or white-box attacks as the standard for defense evaluation; and susceptibility of query-based RE to an AD defense. We also discuss attacks on the privacy of training data. We then present benchmark comparisons of several defenses against TTE, RE, and backdoor DP attacks on images. The article concludes with a discussion of continuing research directions, including the supreme challenge of detecting attacks whose goal is not to alter classification decisions, but rather simply to embed, without detection, "fake news" or other false content.
A Concise History of Mycotoxin Research Pitt, John I; Miller, J. David
Journal of agricultural and food chemistry,
08/2017, Letnik:
65, Številka:
33
Journal Article
Recenzirano
Toxigenic fungi and mycotoxins entered human food supplies about the time when mankind first began to cultivate crops and to store them from one season to the next, perhaps 10,000 years ago. The ...storage of cereals probably initiated the transition by mankind from hunter-gatherer to cultivator, at the same time providing a vast new ecological niche for fungi pathogenic on grain crops or saprophytic on harvested grain, many of which produced mycotoxins. Grains have always been the major source of mycotoxins in the diet of man and his domestic animals. In the historical context, ergotism from Claviceps purpurea in rye has been known probably for more than 2000 years and caused the deaths of many thousands of people in Europe in the last millennium. Known in Japan since the 17th century, acute cardiac beriberi associated with the consumption of moldy rice was found to be due to citreoviridin produced by Penicillium citreonigrum. This toxin was believed to be only of historic importance until its reemergence in Brazil a few years ago. Other Penicillium toxins, including ochratoxin A, once considered to be a possible cause of Balkan endemic nephropathy, are treated in a historical context. The role of Fusarium toxins in human and animal health, especially T-2 toxin in alimentary toxic aleukia in Russia in the 1940s and fumonisins in equine leucoencephalomalasia, is set out in some detail. Finally, this paper documents the story of the research that led to our current understanding of the formation of aflatoxins in grains and nuts, due to the growth of Aspergillus flavus and its role, in synergy with the hepatitis B virus, in human liver cancer. During a period of climate change and greatly reduced crop diversity on a global basis, researchers tasked with monitoring the food system need to be aware of fungal toxins that might have been rare in their working careers that can reappear.
As atmospheric levels of CO(2) increase, reef-building corals are under greater stress from both increased sea surface temperatures and declining sea water pH. To date, most studies have focused on ...either coral bleaching due to warming oceans or declining calcification due to decreasing oceanic carbonate ion concentrations. Here, through the use of physiology measurements and cDNA microarrays, we show that changes in pH and ocean chemistry consistent with two scenarios put forward by the Intergovernmental Panel on Climate Change (IPCC) drive major changes in gene expression, respiration, photosynthesis and symbiosis of the coral, Acropora millepora, before affects on biomineralisation are apparent at the phenotype level. Under high CO(2) conditions corals at the phenotype level lost over half their Symbiodinium populations, and had a decrease in both photosynthesis and respiration. Changes in gene expression were consistent with metabolic suppression, an increase in oxidative stress, apoptosis and symbiont loss. Other expression patterns demonstrate upregulation of membrane transporters, as well as the regulation of genes involved in membrane cytoskeletal interactions and cytoskeletal remodeling. These widespread changes in gene expression emphasize the need to expand future studies of ocean acidification to include a wider spectrum of cellular processes, many of which may occur before impacts on calcification.
Intermediate-risk patients with aortic stenosis were randomly assigned to undergo either transcatheter or surgical aortic-valve replacement. At 5 years, there was no significant difference between ...the two groups in the incidence of death or disabling stroke. The incidence of aortic regurgitation was higher with transcatheter AVR.
The Montreal Protocol was designed to protect the stratospheric ozone layer by enabling reductions in the abundance of ozone-depleting substances such as chlorofluorocarbons (CFCs) in the atmosphere
.... The reduction in the atmospheric concentration of trichlorofluoromethane (CFC-11) has made the second-largest contribution to the decline in the total atmospheric concentration of ozone-depleting chlorine since the 1990s
. However, CFC-11 still contributes one-quarter of all chlorine reaching the stratosphere, and a timely recovery of the stratospheric ozone layer depends on a sustained decline in CFC-11 concentrations
. Here we show that the rate of decline of atmospheric CFC-11 concentrations observed at remote measurement sites was constant from 2002 to 2012, and then slowed by about 50 per cent after 2012. The observed slowdown in the decline of CFC-11 concentration was concurrent with a 50 per cent increase in the mean concentration difference observed between the Northern and Southern Hemispheres, and also with the emergence of strong correlations at the Mauna Loa Observatory between concentrations of CFC-11 and other chemicals associated with anthropogenic emissions. A simple model analysis of our findings suggests an increase in CFC-11 emissions of 13 ± 5 gigagrams per year (25 ± 13 per cent) since 2012, despite reported production being close to zero
since 2006. Our three-dimensional model simulations confirm the increase in CFC-11 emissions, but indicate that this increase may have been as much as 50 per cent smaller as a result of changes in stratospheric processes or dynamics. The increase in emission of CFC-11 appears unrelated to past production; this suggests unreported new production, which is inconsistent with the Montreal Protocol agreement to phase out global CFC production by 2010.
► A buckling-restrained brace with NiTi shape memory alloy was investigated. ► NiTi shape memory alloy tests examine effects of heat treatment and machining. ► Two large-scale braces exhibit robust ...behavior and significant self-centering. ► The prototype braces provide a basis for studying implementation in systems.
Buildings designed with conventional ductile earthquake-resisting structural systems are expected to provide life safety performance, but they rely on significant structural damage to dissipate the seismic energy. This structural damage and the residual drift that may result from the inelastic response can make a building difficult, if not financially unreasonable, to repair after an earthquake. As a result, development of systems that dissipate energy, minimize structural damage, and return to their initial position (“self-center”) following an earthquake is needed. This paper presents a viable solution including experimental investigation of the cyclic behavior and performance of a self-centering buckling-restrained brace (SC-BRB). A SC-BRB consists of a typical BRB component, which provides energy dissipation, and pre-tensioned superelastic nickel–titanium (NiTi) shape memory alloy (SMA) rods, which provide self-centering and additional energy dissipation. The SMA rods are attached to the BRB portion of the brace using a set of concentric tubes and free-floating end plates that cause the SMA rods to elongate when the brace is in both tension and compression. Large-scale SC-BRBs were designed, fabricated and tested using a cyclic protocol to validate the brace concept. The experimental program demonstrated that NiTi SMA SC-BRBs provide stable hysteretic response with appreciable energy dissipation, self-centering ability, and large maximum and cumulative deformation capacities.
Trait-based approaches have improved our understanding of plant evolution, community assembly and ecosystem functioning. A major challenge for the upcoming decades is to understand the functions and ...evolution of early life-history traits, across levels of organization and ecological strategies. Although a variety of seed traits are critical for dispersal, persistence, germination timing and seedling establishment, only seed mass has been considered systematically. Here we suggest broadening the range of morphological, physiological and biochemical seed traits to add new understanding on plant niches, population dynamics and community assembly. The diversity of seed traits and functions provides an important challenge that will require international collaboration in three areas of research. First, we present a conceptual framework for a seed ecological spectrum that builds upon current understanding of plant niches. We then lay the foundation for a seed-trait functional network, the establishment of which will underpin and facilitate trait-based inferences. Finally, we anticipate novel insights and challenges associated with incorporating diverse seed traits into predictive evolutionary ecology, community ecology and applied ecology. If the community invests in standardized seed-trait collection and the implementation of rigorous databases, major strides can be made at this exciting frontier of functional ecology.
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