69 research outputs found

    The second law and beyond in microscopic quantum setups

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    The Clausius inequality (CI) is one of the most versatile forms of the second law. Although it was originally conceived for macroscopic steam engines, it is also applicable to quantum single particle machines. Moreover, the CI is the main connecting thread between classical microscopic thermodynamics and nanoscopic quantum thermodynamics. In this chapter, we study three different approaches for obtaining the CI. Each approach shows different aspects of the CI. The goals of this chapter are: (i) To show the exact assumptions made in various derivations of the CI. (ii) To elucidate the structure of the second law and its origin. (iii) To discuss the possibilities each approach offers for finding additional second-law like inequalities. (iv) To pose challenges related to the second law in nanoscopic setups. In particular, we introduce and briefly discuss the notions of exotic heat machines (X machines), and "lazy demons".Comment: As a chapter of: F. Binder, L. A. Correa, C. Gogolin, J. Anders, and G. Adesso (eds.), "Thermodynamics in the quantum regime - Recent Progress and Outlook", (Springer International Publishing). v1 does not include references to other book chapter

    Photosynthesis by six portuguese maize cultivars during drought stress and recovery

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    Photosynthesis, chlorophyll fluorescence and leaf water parameters were measured in six Portuguese maize (Zea mays L.) cultivars during and following a period of drought stress. The leaf relative water content (RWC) responded differently among cultivars but, except for cultivar PB369, recovered close to initial values after watering was restored. Photosynthetic rate and stomatal conductance decreased with drought but more slowly in cultivars PB269 and PB260 than in cultivars AD3R, PB64, PB304 and PB369. Water use efficiency (WUE) decreased during the water stress treatment although with cultivar PB260 the decrease was marked only when the RWC fell below 40%. Recovery of WUE was seen with all cultivars except PB369. The maximum quantum efficiency of photosystem II, the photochemical quenching coefficient, the electron transport rate in PSII and the estimated functional plastoquinone pool tended to decrease with drought, while the non -photochemical quenching coefficient increased. The parameters estimated from chlorophyll fluorescence did not recover in PB369, during re - watering. The results show that PB260 and PB269 were the most tolerant and PB369 was the least tolerant cultivars to water stress. The variation found amongst the cultivars tested suggests the existence of valuable genetic resources for crop improvement in relation to drought tolerance

    Genomic reconstruction of the SARS-CoV-2 epidemic in England.

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    The evolution of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus leads to new variants that warrant timely epidemiological characterization. Here we use the dense genomic surveillance data generated by the COVID-19 Genomics UK Consortium to reconstruct the dynamics of 71 different lineages in each of 315 English local authorities between September 2020 and June 2021. This analysis reveals a series of subepidemics that peaked in early autumn 2020, followed by a jump in transmissibility of the B.1.1.7/Alpha lineage. The Alpha variant grew when other lineages declined during the second national lockdown and regionally tiered restrictions between November and December 2020. A third more stringent national lockdown suppressed the Alpha variant and eliminated nearly all other lineages in early 2021. Yet a series of variants (most of which contained the spike E484K mutation) defied these trends and persisted at moderately increasing proportions. However, by accounting for sustained introductions, we found that the transmissibility of these variants is unlikely to have exceeded the transmissibility of the Alpha variant. Finally, B.1.617.2/Delta was repeatedly introduced in England and grew rapidly in early summer 2021, constituting approximately 98% of sampled SARS-CoV-2 genomes on 26 June 2021

    Deep sequencing of plant and animal DNA contained within traditional Chinese medicines reveals legality issues and health safety concerns

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    Traditional Chinese medicine (TCM) has been practiced for thousands of years, but only within the last few decades has its use become more widespread outside of Asia. Concerns continue to be raised about the efficacy, legality, and safety of many popular complementary alternative medicines, including TCMs. Ingredients of some TCMs are known to include derivatives of endangered, trade-restricted species of plants and animals, and therefore contravene the Convention on International Trade in Endangered Species (CITES) legislation. Chromatographic studies have detected the presence of heavy metals and plant toxins within some TCMs, and there are numerous cases of adverse reactions. It is in the interests of both biodiversity conservation and public safety that techniques are developed to screen medicinals like TCMs. Targeting both the p-loop region of the plastid trnL gene and the mitochondrial 16S ribosomal RNA gene, over 49,000 amplicon sequence reads were generated from 15 TCM samples presented in the form of powders, tablets, capsules, bile flakes, and herbal teas. Here we show that second-generation, high-throughput sequencing (HTS) of DNA represents an effective means to genetically audit organic ingredients within complex TCMs. Comparison of DNA sequence data to reference databases revealed the presence of 68 different plant families and included genera, such as Ephedra and Asarum, that are potentially toxic. Similarly, animal families were identified that include genera that are classified as vulnerable, endangered, or critically endangered, including Asiatic black bear (Ursus thibetanus) and Saiga antelope (Saiga tatarica). Bovidae, Cervidae, and Bufonidae DNA were also detected in many of the TCM samples and were rarely declared on the product packaging. This study demonstrates that deep sequencing via HTS is an efficient and cost-effective way to audit highly processed TCM products and will assist in monitoring their legality and safety especially when plant reference databases become better established

    Aggregate programming: From foundations to applications

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    We live in a world with an ever-increasing density of computing devices, pervading every aspect of our environment. Programming these devices is challenging, due to their large numbers, potential for frequent and complex network interactions with other nearby devices, and the open and evolving nature of their capabilities and applications. Aggregate programming addresses these challenges by raising the level of abstraction, so that a programmer can operate in terms of collections of interacting devices. In particular, field calculus provides a safe and extensible model for encapsulation, modulation, and composition of services. On this foundation, a set of resilient \u201cbuilding block\u201d operators support development of APIs that can provide resilience and scalability guarantees for any service developed using them. We illustrate the power of this approach by discussion of several recent applications, including crowd safety at mass public events, disaster relief operations, construction of resilient enterprise systems, and network security
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