Abstract
The processing of energy by transfer and redistribution, plays a key role in the evolution of dynamical systems. At the ultrasmall and ultrafast scale of nanosystems, quantum coherence could ...in principle also play a role and has been reported in many pulse-driven nanosystems (e.g. quantum dots and even the microscopic Light-Harvesting Complex II (LHC-II) aggregate). Typical theoretical analyses cannot easily be scaled to describe these general
N
-component nanosystems; they do not treat the pulse dynamically; and they approximate memory effects. Here our aim is to shed light on what new physics might arise beyond these approximations. We adopt a purposely minimal model such that the time-dependence of the pulse is included explicitly in the Hamiltonian. This simple model generates complex dynamics: specifically, pulses of intermediate duration generate highly entangled vibronic (i.e. electronic-vibrational) states that spread multiple excitons – and hence energy – maximally within the system. Subsequent pulses can then act on such entangled states to efficiently channel subsequent energy capture. The underlying pulse-generated vibronic entanglement increases in strength and robustness as
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increases.
Academia-enterprise collaboration is understood as a determinant that improves innovation and competitiveness. The mechanisms by which this collaboration occurs have awakened increasing interest ...among academics, as well as in the business sector. This research aims to identify how open innovation communities can mediate the academia-enterprise relationship, as well as the factors that are more affected by this mediation. Based on the literature, the article addresses the definition of open innovation communities (OICs), university-enterprise cooperation, knowledge transfer (KT), as well as an understanding of OICs as a mechanism for academia-enterprise transfer. An analysis of twelve OICs, conformed by professors, students, graduates, and experts from a Colombian higher education institution is performed. For the data analysis, a factor analysis involving structural equation modeling is carried out. Our results highlight the most important characteristics to take into account in the study of knowledge transfer when OICs are involved, and they also indicate the level of connection between these factors.
We investigate the non-equilibrium quantum dynamics of a canonical light-matter system-namely, the Dicke model-when the light-matter interaction is ramped up and down through a cycle across the ...quantum phase transition. Our calculations reveal a rich set of dynamical behaviors determined by the cycle times, ranging from the slow, near adiabatic regime through to the fast, sudden quench regime. As the cycle time decreases, we uncover a crossover from an oscillatory exchange of quantum information between light and matter that approaches a reversible adiabatic process, to a dispersive regime that generates large values of light-matter entanglement. The phenomena uncovered in this work have implications in quantum control, quantum interferometry, as well as in quantum information theory.
Ultracold polar molecules are an ideal platform for studying many-body physics with long-range dipolar interactions. Experiments in this field have progressed enormously, and several groups are ...pursuing advanced apparatus for manipulation of molecules with electric fields as well as single-atom-resolved in situ detection. Such detection has become ubiquitous for atoms in optical lattices and tweezer arrays, but has yet to be demonstrated for ultracold polar molecules. Here we present a proposal for the implementation of site-resolved microscopy for polar molecules, and specifically discuss a technique for spin-resolved molecular detection. We use numerical simulation of spin dynamics of lattice-confined polar molecules to show how such a scheme would be of utility in a spin-diffusion experiment.
We show that a pulsed stimulus can be used to generate many-body quantum coherences in light-matter systems of general size. Specifically, we calculate the exact time-evolution of an N qubit system ...coupled to a global boson field, in response to an up-down pulse. The pulse is chosen so that the system dynamically crosses the system's quantum phase transition on both the up and down portion of the cycle. We identify a novel form of dynamically-driven quantum coherence emerging for general N and without having to access the empirically challenging strong-coupling regime. Its properties depend on the speed of the changes in the stimulus. Non-classicalities arise within each subsystem that have eluded previous analyses. Our findings show robustness to losses and noise, and have potential functional implications at the systems level for a variety of nanosystems, including collections of N atoms, molecules, spins, or superconducting qubits in cavities—and possibly even vibration-enhanced light-harvesting processes in macromolecules.
Researchers from Alzheimer's Disease Centers (ADCs) across the United States with expertise in the assessment of Spanish-speaking elderly collaborated to create the official Spanish version of ...measures in the Uniform Data Set of the National Institute on Aging Alzheimer's Disease Center Program. The present article describes this project, whose primary goal was to create Spanish instruments with cultural and linguistic equivalence to the English versions. The resulting Spanish versions make provisions for variations among Spanish-speaking groups in the United States of different nationalities, socio-cultural, linguistic, and educational backgrounds. A consensus-based translation and adaptation approach was used, and guiding principles and specific components of this process are summarized. The Spanish translation and adaptation of the Uniform Data Set measures became available online to ADCs in April 2007. Its creation is important, as the resulting effort provides standardized measures for the collection of cross-sectional and longitudinal data on a large cohort of Spanish-speaking elders across the country and facilitates collaborative research among ADCs.
The influence of spatial variability of saturated hydraulic conductivity (K) on drain spacing (L) calculations, based on Kostyakov and Hooghoudt steady state equations, was studied in plots with L ...equal to 10, 20, and 40 m. The drain discharge rate (q) and the midpoint water-table height above the drain were measured. Then, the K values required to obtain the actual drain spacing by means of the equations were found by trial and error. When using the Hooghoudt equation different values of the depth of the "impermeable" layer were also assumed. For the plots with L equal to 10 and 20 m the use of any central tendency estimator of K practically would have produced the actual drain spacing. However, for the plot with L equal to 40 m, none of these estimators would have produced this drain spacing. It is recommended to increase the number of K measurements to at least one per hectare and to use q equal to 0.01 m/d for humid tropical areas with similar climatic, soil and agronomic conditions.
Celotno besedilo
Dostopno za:
DOBA, FGGLJ, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
The synthesis of 7-propynyl-, 7-iodo- and 7-cyano-7-deaza-2-amino-2′-deoxyadenosines is described. The nucleosides were synthesized, functionalized into the phosphoramidites and incorporated into ...oligodeoxynucleotides. Spectroscopic melting experiments against complementary RNA showed increases of 3–4°C per modification for single substitutions and smaller increases per incorporation for multiple substitutions relative to unmodified control sequences. The 7-propyne and 7-iodo nucleosides were incorporated into antisense sequences targeting the 3′-UTR of murine C-raf mRNA. Both nucleosides demonstrated substitution-dependent potency. The sequences with three and four substitutions of the 7-propyne-7-deaza-2-amino-2′-deoxyadenosine exhibited a 2–3-fold increase in potency over unmodifed controls.
Bernal, and subsequently other authors, have suggested that the prebiotic synthesis of the precursors of biopolymers could have occurred on a solid surface such as that provided by clay or some other ...mineral. The separation of products from the other components of the reaction mixture in such a system is reminiscent of modern solid-phase synthesis of polypeptides and polynucleotides. One such scheme envisages that growing polymers were localized by adsorption to a mineral surface where an activating agent or activated monomers were supplied continuously or cyclically. We have been trying to test this scheme using reactions which we believe may be related to those that occurred during prebiotic evolution. We have already reported that oligonucleotides adsorbed onto hydroxylapatite provide suitable templates for the oligomerization of (guanosine 5'-phosphor)-2-methylimidazolide (2-MeImpG). However, this is not a suitable test reaction, as 2-MeImpG oligomerization proceeds almost to completion in a single step. Here we report that a sequence of reactions in which initially formed oligo(G)s are reactivated by conversion to phosphorimidazolides in the presence of poly(C) and then allowed to ligate is ideal, in that repeated cycles can be carried out on the surface of hydroxylapatite, whereas in the liquid phase the cycle could be achieved only with considerable difficulty.
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