Machine learning with the hierarchy‐of‐hypotheses (HoH) approach discovers novel pattern in studies on biological invasions

Research synthesis on simple yet general hypotheses and ideas is challenging in scientific disciplines studying highly context‐dependent systems such as medical, social, and biological sciences. This study shows that machine learning, equation‐free statistical modeling of artificial intelligence, is a promising synthesis tool for discovering novel patterns and the source of controversy in a general hypothesis. We apply a decision tree algorithm, assuming that evidence from various contexts can be adequately integrated in a hierarchically nested structure. As a case study, we analyzed 163 articles that studied a prominent hypothesis in invasion biology, the enemy release hypothesis. We explored if any of the nine attributes that classify each study can differentiate conclusions as classification problem. Results corroborated that machine learning can be useful for research synthesis, as the algorithm could detect patterns that had been already focused in previous narrative reviews. Compared with the previous synthesis study that assessed the same evidence collection based on experts' judgement, the algorithm has newly proposed that the studies focusing on Asian regions mostly supported the hypothesis, suggesting that more detailed investigations in these regions can enhance our understanding of the hypothesis. We suggest that machine learning algorithms can be a promising synthesis tool especially where studies (a) reformulate a general hypothesis from different perspectives, (b) use different methods or variables, or (c) report insufficient information for conducting meta‐analyses

Visualizing the Quantum Interaction Picture in Phase Space

We illustrate the correspondence between the quantum Interaction Picture-evolution of the state of a quantum system in Hilbert space and a combination of local and global transformations of its Wigner function in phase space. To this aim, we consider the time-evolution of a quantized harmonic oscillator driven by both a linear and a quadratic (in terms of bosonic creation and annihilation operators) potentials and employ the Magnus series to derive the exact form of the time-evolution operator. In this case, the Interaction Picture corresponds to a local transformation of phase space-reference frame into the one that is co-moving with the Wigner function.Comment: Submitted to New Journal of Physic

Nonclassicality of a photon-subtracted Gaussian field

Published versio

Life raft stabilizer

An improved life raft stabilizer for reducing rocking and substantially precluding capsizing is discussed. The stabilizer may be removably attached to the raft and is defined by flexible side walls which extend a considerable depth downwardly to one another in the water. The side walls, in conjunction with the floor of the raft, form a ballast enclosure. A weight is placed in the bottom of the enclosure and water port means are provided in the walls. Placement of the stabilizer in the water allows the weighted bottom to sink, producing submerged deployment thereof and permitting water to enter the enclosure through the port means, thus forming a ballast for the raft

Decoherence of Quantum-Enhanced Timing Accuracy

Quantum enhancement of optical pulse timing accuracy is investigated in the Heisenberg picture. Effects of optical loss, group-velocity dispersion, and Kerr nonlinearity on the position and momentum of an optical pulse are studied via Heisenberg equations of motion. Using the developed formalism, the impact of decoherence by optical loss on the use of adiabatic soliton control for beating the timing standard quantum limit [Tsang, Phys. Rev. Lett. 97, 023902 (2006)] is analyzed theoretically and numerically. The analysis shows that an appreciable enhancement can be achieved using current technology, despite an increase in timing jitter mainly due to the Gordon-Haus effect. The decoherence effect of optical loss on the transmission of quantum-enhanced timing information is also studied, in order to identify situations in which the enhancement is able to survive.Comment: 12 pages, 4 figures, submitte

Frictional quantum decoherence

The dynamics associated with a measurement-based master equation for quantum Brownian motion are investigated. A scheme for obtaining time evolution from general initial conditions is derived. This is applied to analyze dissipation and decoherence in the evolution of both a Gaussian and a Schr\"{o}dinger cat initial state. Dependence on the diffusive terms present in the master equation is discussed with reference to both the coordinate and momentum representations.Comment: 18 pages, 7 figure

Non-Markovian dynamics of a nanomechanical resonator measured by a quantum point contact

We study the dynamics of a nanomechanical resonator (NMR) subject to a measurement by a low transparency quantum point contact (QPC) or tunnel junction in the non-Markovian domain. We derive the non-Markovian number-resolved (conditional) and unconditional master equations valid to second order in the tunneling Hamiltonian without making the rotating-wave approximation and the Markovian approximation, generally made for systems in quantum optics. Our non-Markovian master equation reduces, in appropriate limits, to various Markovian versions of master equations in the literature. We find considerable difference in dynamics between the non-Markovian cases and its Markovian counterparts. We also calculate the time-dependent transport current through the QPC which contains information about the measured NMR system. We find an extra transient current term proportional to the expectation value of the symmetrized product of the position and momentum operators of the NMR. This extra current term, with a coefficient coming from the combination of the imaginary parts of the QPC reservoir correlation functions, has a substantial contribution to the total transient current in the non-Markovian case, but was generally ignored in the studies of the same problem in the literature. Considering the contribution of this extra term, we show that a significantly qualitative and quantitative difference in the total transient current between the non-Markovian and the Markovian wide-band-limit cases can be observed. Thus, it may serve as a witness or signature of the non-Markovian features in the coupled NMR-QPC system.Comment: Accepted for publication in Physical Review B (20 pages, 13 figures

The Importance of Animal Comfort for Animal Production in Intensive Grassland Systems

Animals utilise a wide range of regulatory systems to control the conditions within their bodies or homeostasis. These regulatory systems control for example, body temperature, nutritional state, water balance, social interactions and fear and these systems react to environmental and endogenous stimuli so as to correct or prevent displacements from the optimal range. The behavioural and physiological responses utilised by the animal are usually proportional to the challenge to homeostasis. The stress response commences with the central nervous system perceiving a potential challenge to homeostasis. Once the central nervous system perceives a threat, it develops a biological response or defence that consists of some combination of the four general biological defence responses: behavioural responses, responses of the autonomic nervous system, responses of the neuroendocrine system and responses of the immune system. Although biological regulation is occurring constantly, adaptation is not always possible and when homeostasis fails, there are biological costs for the animal, which may include growth and reproductive failure, injury, disease as a consequence of immunosuppression or even death. While animal comfort is not strictly defined in the scientific literature, an appropriate definition of comfort that is utilised in this review is a dictionary definition, “at ease in body and mind”. With the likely trend to greater intensification of grassland production, there are a number of factors that will affect animal comfort. Both group size and space allowance are key features of the social environment that may affect animal comfort, while the nature of human contact is an important factor, which through fear, may also affect animal comfort. Thermal stressors can have significant impact on animal comfort with cold around parturition being a serious problem for the offspring and heat having adverse consequences for adult animal production and welfare. The concerns for animal comfort over husbandry procedures include practices ranging from simple interventions such as shearing that involve challenges including restraint, close human contact and isolation to more complex surgical interventions such as tail docking and castration that may include additional challenges such as acute and chronic pain, as well as short-term production depressions. Others issues include risks associated with animal biotechnologies, including simple manipulations such as twinning to more complex transgenic manipulations