We present results for Shannon entropy from environmental data, such as air temperature, relative humidity, rainfall and wind speed. We use hourly generated time-series hydrological model data covering the whole of Tasmania, a state of Australia, and employ concepts from statistical mechanics in our calculations. We also present enthalpy and heat capacitance equivalent quantities for the environment. The results capture interesting seasonal fluctuations in environmental parameters over time. Our results also present an indication that corresponds to a slight increase in the number of microstates due to air temperature over the duration of data considered in this work.
Calculations of electron-impact ionization cross sections (EIICS) for L-subshell of neutral atoms with atomic number Z = 14-92 and also for M-subshell targets, having atomic number Z 1/4 35-92 for incident energies Ethreshold <= E <= 10(6) keV, have been reported. This review comprises the results of our two easy-to-use models, capable of reproducing very closely the experimental EIICS data. We also show systematically how these models can be implemented easily to generate accurate data as demanded by various model applications. The choice of the range of atomic number Z for both L-and M-subshell targets was made possible by the wealth of the EIICS data in literature either from experiments or from rigorous quantal calculations. The detailed findings due to our XMCN and XMUIBED models are compared with the experimental and other theoretical results. Present results describe the experimental data quite well for the L-and M-subshell for various atomic targets over a wider range of projectile energy.
We report an extension and modification of the MCN model of Haque et al (2013 Rad. Phys. Chem. 91 50-9) (XMCN) to study the electron impact ionization of inner L and M shells of neutral atoms by introducing new parameters of the MCN model. The extended XMCN model, including the relativistic effect, has been applied with success to evaluate ionization cross-sections of various atomic targets with Z = 38-92 for both individual subshells and total L-shell and the corresponding cross-sections for the M shell for Z = 79-92 at incident energies E-Threshold <= T <= 1 GeV. A comparison with other available theoretical and experimental cross-sections reveals that our results reproduce the experimental measurements with a reasonable accuracy.
We present an end-to-end visual analytics framework that aims to facilitate prediction and decision making about honey bee health based on micro sensing data. The framework is particularly tailored to cope with heterogeneous data from micro sensors and environmental sensors that are deployed to collect information about bees and their environment. The framework design allows for a wide range of end users, including scientists, bee keepers, and decision makers, to effectively explore the bee data through interactive visual interfaces. User centred design is deployed throughout the development to meet the various requirements of the users. A large scale study is being planned to evaluate and further refine the framework based on user experiences.
The Sternglass theory [Sternglass, Phys. Rev. 108, (1957) 1] for fast-ion-induced secondary-electron emission, which is proportional to the stopping powers, from metals has been modified to calculate the electron impact secondary electron yield from both elemental and compound targets with atomic number Z = 4-92 for incident energy range 5 <= E-i <= 10(5) eV. This modification includes the use of a realistic stopping power expression that involves calculations of the effective atomic electron number, effective mean excitation energies and realistic electron density distribution of the target atoms along with the effective charge of incident electron. Throughout the studied energy range, the predictions of our proposed theory are in reasonable agreement with the experimental data for Be to U elemental and six important compound targets. (C) 2017 Elsevier Ltd. All rights reserved.
The spin-polarization S and the spin-polarization parametersUand T of the elastically scattered electrons from Hg atoms have been computed for scattering angles 0 degrees-180 degrees in the energy range 1 eV <= Ei <= 2 keV. An optical model approach is employed using a complex optical potential within the framework of the Dirac relativistic partial wave analysis. Wecompare our results with recent experiments and available theoretical calculations and find a reasonable agreement with experiments over a wide range of energies.
We propose a novel approach for calculating an air temperature entropy of environment over a region using concepts from statistical mechanics. The proposed method is intended for use in analysing spatially distributed environmental data. Spatially distributed environmental time-series temperature data from an atmospheric model have been used to illustrate this approach. Our results show that entropy reveals the underlying structure of a data distribution for which a standard statistical analysis may be insufficient.
This brief review focuses on the low-lying even- and odd-parity excitations of the nucleon obtained in recent lattice QCD calculations. Commencing with a survey of the 2014-15 literature we'll see that results for the first even-parity excitation energy can differ by as much as 1 GeV, a rather unsatisfactory situation. Following a brief review of the methods used to isolate excitations of the nucleon in lattice QCD, and drawing on recent advances, we'll see how a consensus on the low-lying spectrum has emerged among many different lattice groups. To provide insight into the nature of these states we'll review the wave functions and electromagnetic form factors that are available for a few of these states. Consistent with the Luscher formalism for extracting phase shifts from finite volume spectra, the Hamiltonian approach to effective field theory in finite volume can provide guidance on the manner in which physical quantities manifest themselves in the finite volume of the lattice. With this insight, we will address the question; Have we seen the Roper in lattice QCD?
Here we present preliminary results for the evaluation of the electromagnetic form factors for the lowest-lying negative-parity, spin-$\frac{1}{2}$ nucleons, namely the $S_{11}(1535)$ and $S_{11}(1650)$, through the use of the variational method. We find that the characteristics of the electric form factor, $G_{E}$, are similar between these states, however significant differences are observed between the quark-sector contributions to the magnetic form factor, $G_{M}$. Within simple constituent quark models, these states are understood to be admixtures of $s=\frac{1}{2}$ and $s=\frac{3}{2}$ states coupled to orbital angular momentum $\ell = 1$. Our results reveal a qualitative difference in the manner in which the singly-represented quark sector contributes to these baryon magnetic form factors.
With the ongoing experimental interest in exploring the excited hadron spectrum, evaluations of the matrix elements describing the formation and decay of such states via radiative processes provide us with an important connection between theory and experiment. In particular, determinations obtained via the lattice allow for a direct comparison of QCD-expectation with experimental observation. Here we present the first light quark determination of the ρ→πγ transition form factor from lattice QCD using dynamical quarks. Using the PACS-CS 2+1 flavour QCD ensembles we are able to obtain results across a range of masses, to the near physical value of m_π = 157 MeV. An important aspect of our approach is the use of variational methods to isolate the desired QCD eigenstate. For low-lying states, such techniques facilitate the removal of excited state contributions. In principle the method enables one to consider arbitrary eigenstates. We find our results are in accord with the non-relativistic quark model for heavy masses. In moving towards the light-quark regime we observe an interesting quark mass dependence, contrary to the quark model expectation. Comparison of our light-quark result with experimental determinations highlights a significant discrepancy suggesting that disconnected sea-quark loop contributions may play a significant role in fully describing this process.
In recent years, the use of variational analysis techniques in lattice QCD has been demonstrated to be successful in the investigation of the rest-mass spectrum of many hadrons. However, due to parity-mixing, more care must be taken for investigations of boosted states to ensure that the projected correlation functions provided by the variational analysis correspond to the same states at zero momentum. In this paper we present the Parity-Expanded Variational Analysis (PEVA) technique, a novel method for ensuring the successful and consistent isolation of boosted baryons through a parity expansion of the operator basis used to construct the correlation matrix.
With the ongoing experimental interest in exploring the excited hadron spectrum, evaluations of the matrix elements describing the formation and decay of such states via radiative processes provide us with an important connection between theory and experiment. In particular, determinations obtained via the lattice allow for a direct comparison of QCD-expectation with experimental observation. Here we present the first light quark determination of the $ρ\rightarrow πγ$ transition form factor from lattice QCD using dynamical quarks. Using the PACS-CS 2+1 flavour QCD ensembles we are able to obtain results across a range of masses, to the near physical value of $m_π= 157$ MeV. An important aspect of our approach is the use of variational methods to isolate the desired QCD eigenstate. For low-lying states, such techniques facilitate the removal of excited state contributions. In principle the method enables one to consider arbitrary eigenstates. We find our results are in accord with the non-relativistic quark model for heavy masses. In moving towards the light-quark regime we observe an interesting quark mass dependence, contrary to the quark model expectation. Comparison of our light-quark result with experimental determinations highlights a significant discrepancy suggesting that disconnected sea-quark loop contributions may play a significant role in fully describing this process.
The ability for most hadrons to decay via strong interactions prevents the direct measurement of their electromagnetic properties. However, a detailed understanding of how these resonant states feature in scattering processes can allow one to disentangle such information from photo production processes. In particular, there has been increasing interest in the determination of magnetic dipole moments using such methods. In a recent study [1], Gudino et al. provide the first experimental determination of the magnetic dipole moment of the rho meson. To facilitate a comparison with this experimental determination, we present a calculation of the rho meson and pion electromagnetic form factors calculated in the framework of lattice QCD. Using the PACS-CS 2 + 1 flavor full QCD gauge field configurations, we are able to access low Q(2) values at near-physical quark masses. Through the use of variational techniques, we control excited state systematics in the matrix elements of the lowest-lying states and gain access to the matrix elements of the first excited state. Our determination of the rho meson g-factor g(rho) = 2.21(8) is in excellent agreement with this experimental determination, but with a significantly smaller uncertainty.
Building on our successful technique to isolate the otherwise-elusive Λ(1405) using correlation matrix techniques and multiple source and sink smearings, we present calculations of the quark sector contributions to the electric form factors of the Λ(1405).Using the PACS-CS (2 + 1)flavour full-QCD ensembles available through the ILDG, our calculations reveal behaviour consistent with the development of a non-trivial molecular KN bound-state component as one approaches the physical values of the u and d quark masses.
We explore the Euclidean-time tails of odd-parity nucleon correlation functions in a search for the S-wave pion-nucleon scattering-state threshold contribution. The analysis is performed using 2+1 flavor 32^3 x 64 PACS-CS gauge configurations available via the ILDG. Correlation matrices composed with various levels of fermion source/sink smearing are used to project low-lying states. The consideration of 25,600 fermion propagators reveals the presence of more than one state in what would normally be regarded as an eigenstate-projected correlation function. This observation is in accord with the scenario where the eigenstates contain a strong mixing of single and multi-particle states but only the single particle component has a strong coupling to the interpolating field. Employing a two-exponential fit to the eigenvector-projected correlation function, we are able to confirm the presence of two eigenstates. The lower-lying eigenstate is consistent with a N-pi scattering threshold and has a relatively small coupling to the three-quark interpolating field. We discuss the impact of this small scattering-state contamination in the eigenvector projected correlation function on previous results presented in the literature.
We present a first look at the application of variational techniques for the extraction of the electromagnetic properties of an excited nucleon system. In particular, we include preliminary results for charge radii and magnetic moments of the proton, its first even-parity excitation and the Δ^+.
The world's first examination of the odd-parity nucleon spectrum at light quark masses in 2+1 flavor lattice QCD is presented. Configurations generated by the PACS-CS collaboration and made available through the ILDG are used, with the lightest pion mass at 156 MeV. A novel method for tracking the individual energy eigenstates as the quark mass changes is introduced. The success of this approach reveals the flow of the states towards the physical masses. Using the correlation matrix method, the two lowest-energy states revealed are found to be in accord with the physical spectrum of Nature.
Building on our successful technique to isolate the otherwise-elusive $\Lambda$(1405) using correlation matrix techniques and multiple source and sink smearings, we present calculations of the quark sector contributions to the electric form factors of the $\Lambda$(1405). Using the PACS-CS $(2+1)$-flavour full-QCD ensembles available through the ILDG, our calculations reveal behaviour consistent with the development of a non-trivial molecular $\overline{K}N$ bound-state component as one approaches the physical values of the $u$ and $d$ quark masses.