1,918 research outputs found
Effects of Low Tide Rainfall on Intertidal Zone Material Cycling
Sediment transport by rainfall-runoff processes is well documented for terrestrial landscapes but few studies have focused on rainfall-runoff effects in intertidal areas. Here we present geochemical analyses performed on sediment samples collected during low tide irrigation experiments, and tidal channel turbidity measurements taken during natural rainfall over North Inlet Marsh, South Carolina. Order of magnitude approximations indicate that a single 10 minute storm may entrain 8-15% of the local annual average sediment accumulation. This rainfall-entrained material is enriched in organic nitrogen and marine algal matter, and therefore of high nutritional quality
Lattice dynamics and vibrational spectra of the orthorhombic, tetragonal and cubic phases of methylammonium lead iodide
The hybrid halide perovskite CH3NH3PbI3 exhibits a complex structural
behaviour, with successive transitions between orthorhombic, tetragonal and
cubic polymorphs at ca. 165 K and 327 K. Herein we report first-principles
lattice dynamics (phonon spectrum) for each phase of CH3NH3PbI3. The
equilibrium structures compare well to solutions of temperature-dependent
powder neutron diffraction. By following the normal modes we calculate infrared
and Raman intensities of the vibrations, and compare them to the measurement of
a single crystal where the Raman laser is controlled to avoid degradation of
the sample. Despite a clear separation in energy between low frequency modes
associated with the inorganic PbI3 network and high-frequency modes of the
organic CH3NH3+ cation, significant coupling between them is found, which
emphasises the interplay between molecular orientation and the corner-sharing
octahedral networks in the structural transformations. Soft modes are found at
the boundary of the Brillouin zone of the cubic phase, consistent with
displacive instabilities and anharmonicity involving tilting of the PbI6
octahedra around room temperature.Comment: 9 pages, 4 figure
SBOL-OWL: An ontological approach for formal and semantic representation of synthetic biology information
Standard representation of data is key for the reproducibility of designs in synthetic biology. The Synthetic Biology Open Language (SBOL) has already emerged as a data standard to represent information about genetic circuits, and it is based on capturing data using graphs. The language provides the syntax using a free text document that is accessible to humans only. This paper describes SBOL-OWL, an ontology for a machine understandable definition of SBOL. This ontology acts as a semantic layer for genetic circuit designs. As a result, computational tools can understand the meaning of design entities in addition to parsing structured SBOL data. SBOL-OWL not only describes how genetic circuits can be constructed computationally, it also facilitates the use of several existing Semantic Web tools for synthetic biology. This paper demonstrates some of these features, for example, to validate designs and check for inconsistencies. Through the use of SBOL-OWL, queries can be simplified and become more intuitive. Moreover, existing reasoners can be used to infer information about genetic circuit designs that cannot be directly retrieved using existing querying mechanisms. This ontological representation of the SBOL standard provides a new perspective to the verification, representation, and querying of information about genetic circuits and is important to incorporate complex design information via the integration of biological ontologies
Semiquantitative theory of electronic Raman scattering from medium-size quantum dots
A consistent semiquantitative theoretical analysis of electronic Raman
scattering from many-electron quantum dots under resonance excitation
conditions has been performed. The theory is based on
random-phase-approximation-like wave functions, with the Coulomb interactions
treated exactly, and hole valence-band mixing accounted for within the
Kohn-Luttinger Hamiltonian framework. The widths of intermediate and final
states in the scattering process, although treated phenomenologically, play a
significant role in the calculations, particularly for well above band gap
excitation. The calculated polarized and unpolarized Raman spectra reveal a
great complexity of features and details when the incident light energy is
swept from below, through, and above the quantum dot band gap. Incoming and
outgoing resonances dramatically modify the Raman intensities of the single
particle, charge density, and spin density excitations. The theoretical results
are presented in detail and discussed with regard to experimental observations.Comment: Submitted to Phys. Rev.
Wigner Crystal in One Dimension
A one--dimensional gas of electrons interacting with long--range Coulomb
forces () is investigated. The excitation spectrum consists
of separate collective charge and spin modes, with the charge excitation
energies in agreement with RPA calculations. For arbitrarily weak Coulomb
repulsion density correlations at wavevector decay extremely slowly and
are best described as those of a one--dimensional Wigner crystal. Pinning of
the Wigner crystal then leads to the nonlinear transport properties
characteristic of CDW. The results allow a consistent interpretation of the
plasmon and spin excitations observed in one--dimensional semiconductor
structures, and suggest an interpretation of some of the observed features in
terms of ``spinons''. A possible explanation for nonlinear transport phenomena
is given.Comment: 10 pages, RevTe
Tunneling Between a Pair of Parallel Hall Droplets
In this paper, we examine interwell tunneling between a pair of fractional
quantum Hall liquids in a double quantum well system in a tilted magnetic
field. Using a variational Monte Carlo method, we calculate moments of the
intra-Landau level tunneling spectrum as a function of in-plane field component
and interwell spacing . This is done for variety of
incompressible states including a pair of layers ([330]), pair of
layers ([550]), and Halperin's [331] state. The results suggest a
technique to extract interwell correlations from the tunneling spectral data.Comment: 21 pages and 8 figures (included), RevTeX, preprint no. UCSDCU
Electronic states, Mott localization, electron-lattice coupling, and dimerization for correlated one-dimensional systems. II
We discuss physical properties of strongly correlated electron states for a
linear chain obtained with the help of the recently proposed new method
combining the exact diagonalization in the Fock space with an ab initio
readjustment of the single-particle orbitals in the correlated state. The
method extends the current discussion of the correlated states since the
properties are obtained with varying lattice spacing. The finite system of N
atoms evolves with the increasing interatomic distance from a Fermi-liquid-like
state into the Mott insulator. The criteria of the localization are discussed
in detail since the results are already convergent for N>=8. During this
process the Fermi-Dirac distribution gets smeared out, the effective band mass
increases by ~50%, and the spin-spin correlation functions reduce to those for
the Heisenberg antiferromagnet. Values of the microscopic parameters such as
the hopping and the kinetic-exchange integrals, as well as the magnitude of
both intra- and inter-atomic Coulomb and exchange interactions are calculated.
We also determine the values of various local electron-lattice couplings and
show that they are comparable to the kinetic exchange contribution in the
strong-correlation limit. The magnitudes of the dimerization and the zero-point
motion are also discussed. Our results provide a canonical example of a
tractable strongly correlated system with a precise, first-principle
description as a function of interatomic distance of a model system involving
all hopping integrals, all pair-site interactions, and the exact one-band
Wannier functions.Comment: 18 pages, REVTEX, submitted to Phys. Rev.
Pengaruh Fungsi Pengawasan Dewan Perwakilan Rakyat Daerah (DPRD) terhadap Penggunaan Anggaran Pendapatan dan Belanja Daerah (APBD) di Kabupaten Minahasa Selatan
In carrying out oversight functions, the Regional Representatives Council (DPRD) equippedwith special rights that can support the effectiveness of the work as one of the institutions of control in thearea. and most importantly that in determining whether or not accepted the draft budget proposed by theexecutive, the Regional Representatives Council (DPRD) had a very big right. Based on an evaluation ofthe State Audit Board (BPK) of the Republic of Indonesia through the representatives of North Sulawesi,assess the use of the Regional Budget (APBD) South Minahasa, from Fiscal Year 2009 to 2012 Budgetgets a "disclaimer, meaning that can not be assessed and checks in Budget 2014, to use the RegionalBudget (APBD) in 2013 there was an increase in ratings of disclaimer to the unnatural. This is due toRevenue and Expenditure Budget (APBD) South Minahasa District by each regional work units (SKPD)does not fit the designation and use of Revenue and Expenditure Budget (APBD) and assets much abusedby the head of the regional work units (SKPD) and subordinates. This study aims: "To analyze the effectof supervisory functions Regional Representatives Council (DPRD) to use the Regional Budget (APBD)South Minahasa District". The method of analysis in this research is quantitative descriptive analysismethod. Results of this research is that the supervision of Parliament is one of the determinant factorsincrease the effectiveness of the use of the budget, particularly in the South Minahasa District. In linewith the Strategic Plan (Restra) South Minahasa District Government which sets one of the priorityprogram is the use of the regional budget (APBD) is done effectively, efficiently and economically orientedpublic interest. Thus, efforts to increase the effectiveness of the use of local budgets is through an increasein the budget managers profesionalism apparatus itself by trying to implement i-budgeting
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