15,687 research outputs found
Deriving the Qubit from Entropy Principles
The Heisenberg uncertainty principle is one of the most famous features of
quantum mechanics. However, the non-determinism implied by the Heisenberg
uncertainty principle --- together with other prominent aspects of quantum
mechanics such as superposition, entanglement, and nonlocality --- poses deep
puzzles about the underlying physical reality, even while these same features
are at the heart of exciting developments such as quantum cryptography,
algorithms, and computing. These puzzles might be resolved if the mathematical
structure of quantum mechanics were built up from physically interpretable
axioms, but it is not. We propose three physically-based axioms which together
characterize the simplest quantum system, namely the qubit. Our starting point
is the class of all no-signaling theories. Each such theory can be regarded as
a family of empirical models, and we proceed to associate entropies, i.e.,
measures of information, with these models. To do this, we move to phase space
and impose the condition that entropies are real-valued. This requirement,
which we call the Information Reality Principle, arises because in order to
represent all no-signaling theories (including quantum mechanics itself) in
phase space, it is necessary to allow negative probabilities (Wigner [1932]).
Our second and third principles take two important features of quantum
mechanics and turn them into deliberately chosen physical axioms. One axiom is
an Uncertainty Principle, stated in terms of entropy. The other axiom is an
Unbiasedness Principle, which requires that whenever there is complete
certainty about the outcome of a measurement in one of three mutually
orthogonal directions, there must be maximal uncertainty about the outcomes in
each of the two other directions.Comment: 8 pages, 3 figure
Barriers to Transport and Mixing in Volume-Preserving Maps with Nonzero Flux
In this paper we identify the geometric structures that restrict transport
and mixing in perturbations of integrable volume-preserving systems with
nonzero net flux. Unlike KAM tori, these objects cannot be continued to the
tori present in the integrable system but are generated by resonance and have a
contractible direction. We introduce a remarkably simple algorithm to analyze
the behavior of these maps and obtain quantitative properties of the tori. In
particular, we present assertions regarding the distribution of the escape
times of the unbounded orbits, the abundance of tori, and the size of the
resonant regions
Discriminating between viable and membrane-damaged cells of the plant pathogen Xylella fastidiosa.
Xylella fastidiosa is a plant pathogenic bacterium with devastating consequences to several crops of economic importance across the world. While this pathogen has been studied for over a century in the United States, several aspects of its biology remain to be investigated. Determining the physiological state of bacteria is essential to understand the effects of its interactions with different biotic and abiotic factors on cell viability. Although X. fastidiosa is culturable, its slow growing nature makes this technique cumbersome to assess the physiological state of cells present in a given environment. PMA-qPCR, i.e. the use of quantitative PCR combined with the pre-treatment of cells with the dye propidium monoazide, has been successfully used in a number of studies on human pathogens to calculate the proportion of viable cells, but has less frequently been tested on plant pathogens. We found that the use of a version of PMA, PMAxx, facilitated distinguishing between viable and non-viable cells based on cell membrane integrity in vitro and in planta. Additional experiments comparing the number of culturable, viable, and total cells in planta would help further confirm our initial results. Enhancers, intended to improve the efficacy of PMAxx, were not effective and appeared to be slightly toxic to X. fastidiosa
KETERSEDIAAN OPERASI JOIN DIPERLUAS KOTERI-k TAK-TERDOMINASI
Penelitian ini bertujuan menganalisis ketersediaan dari koteri- mayoritas tak-terdominasi yang menggunakan operasi join diperluas yaitu penggabungkan koteri- , dan masing-masing atas semesta dan dengan unsur tereliminasi , dimana yang menghasilakan koteri- tak-terdominasi atas semesta . Metode penggabungan koteri- mayoritas tak-terdominasi yang menggunakan operasi join diperluas menghasilkan koteri atas . Hasil ketersediaan dari operasi join kemudian dibandingkan dengan ketersedian dengan menggunakan operasi join. Dari penelitian ini, menunjukkan bahwa ketersedian operasi join memberikan hasil yang lebih baik jika dibandingkan dengan ketersedian dari operasi join
Managing disposal at sea in the Salish Sea to protect Southern Resident killer whale habitat
The Southern Resident Killer Whale (SRKW) population is listed as Endangered under Canada’s Species at Risk Act. As part of its Ocean Protection Plan, Canada is taking action to protect SRKW and their defined Critical Habitat in the Salish Sea. Identified threats to SRKW include noise from vessels, availability of prey, and contaminants. Through the Canadian Environmental Protection Act (CEPA), Environment and Climate Change Canada (ECCC) assesses and permits the disposal of waste at sea, including disposal at a designated site in SRKW habitat. As well, ECCC conducts regular, required monitoring at disposal sites. The monitoring program holds several years of scientific data and reports on contaminant levels in sediment, as well as data on sediment physico-chemistry, benthic invertebrate populations, sediment stratigraphy, hydrology and other parameters for its disposal sites. This talk will discuss research findings from ECCC disposal site monitoring, and ECCC activities to protect SRKW habitat from contamination, with a particular focus on findings and management actions with respect to polychlorinated biphenyls (PCBs). Emerging Contaminants, managing noise from Disposal at Sea activities, and engagement with indigenous peoples will also be discussed
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