2,394 research outputs found
Preservation of Maryland Farmland: A Current Assessment
This Article examines various programs in Maryland, both local and state-wide, to promote the preservation of agricultural land. The author demonstrates the need for such programs and concludes that in order for them to be successful, all levels of government within the state must cooperate and commit themselves to adequate funding and intelligent land-use planning
Cobalt-Porphyrin Catalyzed Electrochemical Reduction of Carbon Dioxide in Water II: Mechanism from First Principles
We apply first principles computational techniques to analyze the
two-electron, multi-step, electrochemical reduction of CO2 to CO in water using
cobalt porphyrin as a catalyst. Density Functional Theory calculations with
hybrid functionals and dielectric continuum solvation are used to determine the
steps at which electrons are added. This information is corroborated with ab
initio molecular dynamics simulations in an explicit aqueous environment which
reveal the critical role of water in stabilizing a key intermediate formed by
CO2 bound to cobalt. Using potential of mean force calculations, the
intermediate is found to spontaneously accept a proton to form a carboxylate
acid group at pH<9.0, and the subsequent cleavage of a C-OH bond to form CO is
exothermic and associated with a small free energy barrier. These predictions
suggest that the proposed reaction mechanism is viable if electron transfer to
the catalyst is sufficiently fast. The variation in cobalt ion charge and spin
states during bond breaking, DFT+U treatment of cobalt 3d orbitals, and the
need for computing electrochemical potentials are emphasized.Comment: 33 pages, 7 figure
Fidelity for imperfect postselection
We describe a simple measure of fidelity for mixed state postselecting
devices. The measure is most appropriate for postselection where the task
performed by the output is only effected by a specific state.Comment: 8 Pages, 8 Figure
Multipartite entanglement in the Fenna-Matthews-Olson (FMO) pigment-protein complex
We investigate multipartite states in the Fenna-Matthews-Olson (FMO)
pigment-protein complex of the green sulfur bacteria using a Lorentzian
spectral density of the phonon reservoir fitted with typical parameter
estimates of the species, P. aestuarii. The evolution of the entanglement
measure of the excitonic W qubit states is evaluated in the picosecond time
range, showing increased revivals in the non-Markovian regime. Similar trends
are observed in the evolution dynamics of the Meyer-Wallach measure of the
N-exciton multipartite state, with results showing that multipartite
entanglement can last from 0.5 to 1 ps, between the Bchls of the FMO complex.
The teleportation and quantum information splitting fidelities associated with
the GHZ and W_A resource states of the excitonic qubit channels of the FMO
complex show that revivals in fidelities increase with the degree of
non-Markovian strength of the decoherent environment. Results indicate that
quantum information processing tasks involving teleportation followed by the
decodification process involving W_A states of the FMO complex, may play a
critical role during coherent oscillations at physiological temperatures.Comment: 16 pages, new figs, typo
Use of Snares to Live-Capture Beavers
Wildlife managers, researchers, and nuisance-control operators often require a nonlethal means of capturing beavers (Castor canadensis). Historically, live-capture has relied on enclosure-type traps such as Bailey or Hancock traps. We describe the live-capture of 231 beavers using snares in southern Illinois from 2002 to 2005. Capture success averaged 5.4 beavers/100 trap-nights. Capture success did not differ between sexes (P = 0.57) or age-classes (P = 0.68). We captured most beavers in haul-out slide sets, surface run sets, or channel sets. Recaptures accounted for 28% (n = 65) of all captures. Mortality rate using snares was 10% and decreased annually during the study period. Snares are advantageous over enclosure-type traps because they have a high capture:cost ratio and are less heavy and cumbersome than traps. However, mortality rates are relatively high, limiting the utility of this technique for some research
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Development of outbred CD1 mouse colonies with distinct standardized gut microbiota profiles for use in complex microbiota targeted studies.
Studies indicate that the gut microbiota (GM) can significantly influence both local and systemic host physiologic processes. With rising concern for optimization of experimental reproducibility and translatability, it is essential to consider the GM in study design. However, GM profiles can vary between rodent producers making consistency between models challenging. To circumvent this, we developed outbred CD1 mouse colonies with stable, complex GM profiles that can be used as donors for a variety of GM transfer techniques including rederivation, co-housing, cross-foster, and fecal microbiota transfer (FMT). CD1 embryos were surgically transferred into CD1 or C57BL/6 surrogate dams that varied by GM composition and complexity to establish four separate mouse colonies harboring GM profiles representative of contemporary mouse producers. Using targeted 16S rRNA amplicon sequencing, subsequent female offspring were found to have similar GM profiles to surrogate dams. Furthermore, breeding colonies of CD1 mice with distinct GM profiles were maintained for nine generations, demonstrating GM stability within these colonies. To confirm GM stability, we shipped cohorts of these four colonies to collaborating institutions and found no significant variation in GM composition. These mice are an invaluable experimental resource that can be used to investigate GM effects on mouse model phenotype
Controlled spontaneous emission
The problem of spontaneous emission is studied by a direct computer
simulation of the dynamics of a combined system: atom + radiation field. The
parameters of the discrete finite model, including up to 20k field oscillators,
have been optimized by a comparison with the exact solution for the case when
the oscillators have equidistant frequencies and equal coupling constants.
Simulation of the effect of multi-pulse sequence of phase kicks and emission by
a pair of atoms shows that both the frequency and the linewidth of the emitted
spectrum could be controlled.Comment: 25 pages including 11 figure
Resource Requirements for Fault-Tolerant Quantum Simulation: The Transverse Ising Model Ground State
We estimate the resource requirements, the total number of physical qubits
and computational time, required to compute the ground state energy of a 1-D
quantum Transverse Ising Model (TIM) of N spin-1/2 particles, as a function of
the system size and the numerical precision. This estimate is based on
analyzing the impact of fault-tolerant quantum error correction in the context
of the Quantum Logic Array (QLA) architecture. Our results show that due to the
exponential scaling of the computational time with the desired precision of the
energy, significant amount of error correciton is required to implement the TIM
problem. Comparison of our results to the resource requirements for a
fault-tolerant implementation of Shor's quantum factoring algorithm reveals
that the required logical qubit reliability is similar for both the TIM problem
and the factoring problem.Comment: 19 pages, 8 figure
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