Non-Markovian Dynamics of Entanglement for Multipartite Systems

Entanglement dynamics for a couple of two-level atoms interacting with independent structured reservoirs is studied using a non-perturbative approach. It is shown that the revival of atom entanglement is not necessarily accompanied by the sudden death of reservoir entanglement, and vice versa. In fact, atom entanglement can revive before, simultaneously or even after the disentanglement of reservoirs. Using a novel method based on the population analysis for the excited atomic state, we present the quantitative criteria for the revival and death phenomena. For giving a more physically intuitive insight, the quasimode Hamiltonian method is applied. Our quantitative analysis is helpful for the practical engineering of entanglement.Comment: 10 pages and 4 figure

Emission spectra of atoms with non-Markovian interaction: Fluorescence in a photonic crystal

We present a formula to evaluate the spontaneous emission spectra of an atom in contact with a radiation field with non-Markovian effects. This formula is written in terms of a two-time correlation of system observables and the environmental correlation function, and depends on the distance between the emitting atom and the detector. As an example, we use it to analyze the fluorescence spectra of a two level atom placed as an impurity in a photonic crystal. The radiation field within those materials has a gap or discontinuity where electromagnetic modes cannot propagate in the stationary limit. In that situation, the atomic emission occurs in the form of evanescent waves which are detected with less efficiency the farther we place the detector. The methodology presented in this paper may be useful to study the non-Markovian dynamics of any quantum open system in linear interaction with a harmonic oscillator reservoir and within the weak coupling approximation

Using species attributes to characterize late-glacial and early-Holocene environments at Kråkenes, western Norway

Aim: We aim to use species attributes such as distributions and indicator values to reconstruct past biomes, environment, and temperatures from detailed plant‐macrofossil data covering the late glacial to the early Holocene (ca. 14–9 ka). Location: Kråkenes, western Norway. Methods: We applied attributes for present‐day geographical distribution, optimal July and January temperatures, and Ellenberg indicator values for plants in the macrofossil data‐set. We used assemblage weighted means (AWM) to reconstruct past biomes, changes in light (L), nitrogen (N), moisture (F), and soil reaction (R), and temperatures. We compared the temperature reconstructions with previous chironomid‐inferred temperatures. Results: After the start of the Holocene around 11.5 ka, the Arctic‐montane biome, which was stable during the late‐glacial period, shifted successively into the Boreo‐arctic montane, Wide‐boreal, Boreo‐montane, Boreo‐temperate, and Wide‐temperate biomes by ca. 9.0 ka. Circumpolar and Eurasian floristic elements characteristic of the late‐glacial decreased and the Eurosiberian element became prominent. Light demand (L), soil moisture (F), nitrogen (N), and soil reaction (R) show different, but complementary responses. Light‐demanding plants decreased with time. Soil moisture was relatively stable until it increased during organic soil development during the early Holocene. Soil nitrogen increased during the early Holocene. Soil reaction (pH) decreased during the Allerød, but increased during the Younger Dryas. It decreased markedly after the start of the Holocene, reaching low but stable levels in the early Holocene. Mean July and January temperatures show similar patterns to the chironomid‐inferred mean July temperature trends at Kråkenes, but chironomids show larger fluctuations and interesting differences in timing. Conclusion: Assigning attributes to macrofossil species is a useful new approach in palaeoecology. It can demonstrate changes in biomes, ecological conditions, and temperatures. The late‐glacial to early‐Holocene transition may form an analogue for changes observed in the modern arctic and in mountains, with melting glaciers, permafrost thaw, and shrub encroachment into tundra.publishedVersio

Inhibition of Decoherence due to Decay in a Continuum

We propose a scheme for slowing down decay into a continuum. We make use of a sequence of ultrashort $2\pi$-pulses applied on an auxiliary transition of the system so that there is a destructive interference between the two transition amplitudes - one before the application of the pulse and the other after the application of the pulse. We give explicit results for a structured continuum. Our scheme can also inhibit unwanted transitions.Comment: 11 pages and 4 figures, submitted to Physical Review Letter

Quantum memory for photons: I. Dark state polaritons

An ideal and reversible transfer technique for the quantum state between light and metastable collective states of matter is presented and analyzed in detail. The method is based on the control of photon propagation in coherently driven 3-level atomic media, in which the group velocity is adiabatically reduced to zero. Form-stable coupled excitations of light and matter (``dark-state polaritons'') associated with the propagation of quantum fields in Electromagnetically Induced Transparency are identified, their basic properties discussed and their application for quantum memories for light analyzed.Comment: 13 pages, 6 figures, paragraph on photon echo adde

Theory of Pseudomodes in Quantum Optical Processes

This paper deals with non-Markovian behaviour in atomic systems coupled to a structured reservoir of quantum EM field modes, with particular relevance to atoms interacting with the field in high Q cavities or photonic band gap materials. In cases such as the former, we show that the pseudo mode theory for single quantum reservoir excitations can be obtained by applying the Fano diagonalisation method to a system in which the atomic transitions are coupled to a discrete set of (cavity) quasimodes, which in turn are coupled to a continuum set of (external) quasimodes with slowly varying coupling constants and continuum mode density. Each pseudomode can be identified with a discrete quasimode, which gives structure to the actual reservoir of true modes via the expressions for the equivalent atom-true mode coupling constants. The quasimode theory enables cases of multiple excitation of the reservoir to now be treated via Markovian master equations for the atom-discrete quasimode system. Applications of the theory to one, two and many discrete quasimodes are made. For a simple photonic band gap model, where the reservoir structure is associated with the true mode density rather than the coupling constants, the single quantum excitation case appears to be equivalent to a case with two discrete quasimodes

Applications of Site-Specific Labeling to Study HAMLET, a Tumoricidal Complex of α-Lactalbumin and Oleic Acid

umor cells), and its tumoricidal activity has been well established.-acetylgalactosaminyltransferase II (ppGalNAc-T2) and further conjugated with aminooxy-derivatives of fluoroprobe or biotin molecules.We found that the molten globule form of hLA and αD-hLA proteins, with or without C-terminal extension, and with and without the conjugated fluoroprobe or biotin molecule, readily form a complex with OA and exhibits tumoricidal activity similar to HAMLET made with full-length hLA protein. The confocal microscopy studies with fluoroprobe-labeled samples show that these proteins are internalized into the cells and found even in the nucleus only when they are complexed with OA. The HAMLET conjugated with a single biotin molecule will be a useful tool to identify the cellular components that are involved with it in the tumoricidal activity

Decreased Aerobic Exercise Capacity After Long-Term Remission From Cushing Syndrome: Exploration of Mechanisms.

BACKGROUND: Although major improvements are achieved after cure of Cushing syndrome (CS), fatigue and decreased quality of life persist. This is the first study to measure aerobic exercise capacity in patients in remission of CS for more than 4 years in comparison with matched controls, and to investigate whether the reduction in exercise capacity is related to alterations in muscle tissue. METHODS: Seventeen patients were included. A control individual, matched for sex, estrogen status, age, body mass index, smoking, ethnicity, and physical activity level was recruited for each patient. Maximal aerobic capacity (VO2peak) was assessed during incremental bicycle exercise to exhaustion. In 8 individually matched patients and controls, a percutaneous muscle biopsy was obtained and measures were made of cross-sectional areas, capillarization, and oxphos complex IV (COXIV) protein content as an indicator of mitochondrial content. Furthermore, protein content of endothelial nitric oxide synthase (eNOS) and eNOS phosphorylated on serine1177 and of the NAD(P)H-oxidase subunits NOX2, p47phox, and p67phox were measured in the microvascular endothelial layer. FINDINGS: Patients showed a lower mean VO2peak (SD) (28.0 [7.0] vs 34.8 [7.9] ml O2/kg bw/min, P < .01), maximal workload (SD) (176 [49] vs 212 [67] watt, P = .01), and oxygen pulse (SD) (12.0 [3.7] vs 14.8 [4.2] ml/beat, P < .01) at VO2peak. No differences were seen in muscle fiber type-specific cross-sectional area, capillarization measures, mitochondrial content, and protein content of eNOS, eNOS-P-ser1177, NOX2, p47phox, and p67phox. INTERPRETATION: Because differences in muscle fiber and microvascular outcome measures are not statistically significant, we hypothesize that cardiac dysfunction, seen in active CS, persists during remission and limits blood supply to muscles

The Peripheral Binding of 14-3-3γ to Membranes Involves Isoform-Specific Histidine Residues

Mammalian 14-3-3 protein scaffolds include seven conserved isoforms that bind numerous phosphorylated protein partners and regulate many cellular processes. Some 14-3-3-isoforms, notably γ, have elevated affinity for membranes, which might contribute to modulate the subcellular localization of the partners and substantiate the importance of investigating molecular mechanisms of membrane interaction. By applying surface plasmon resonance we here show that the binding to phospholipid bilayers is stimulated when 14-3-3γ is complexed with its partner, a peptide corresponding to the Ser19-phosphorylated N-terminal region of tyrosine hydroxylase. Moreover, membrane interaction is dependent on salts of kosmotropic ions, which also stabilize 14-3-3γ. Electrostatic analysis of available crystal structures of γ and of the non-membrane-binding ζ-isoform, complemented with molecular dynamics simulations, indicate that the electrostatic potential distribution of phosphopeptide-bound 14-3-3γ is optimal for interaction with the membrane through amphipathic helices at the N-terminal dimerization region. In addition, His158, and especially His195, both specific to 14-3-3γ and located at the convex lateral side, appeared to be pivotal for the ligand induced membrane interaction, as corroborated by site-directed mutagenesis. The participation of these histidine residues might be associated to their increased protonation upon membrane binding. Overall, these results reveal membrane-targeting motifs and give insights on mechanisms that furnish the 14-3-3γ scaffold with the capacity for tuned shuffling from soluble to membrane-bound states.This work was supported by grants from the Norwegian Cancer Society (to ØH), Junta de Andalucía, grant CVI-02483 (to JMSR), The Research Council of Norway (grant 185181 to A.M.), the Western Norway Health Authorities (grant 911618 to A.M.) and The Kristian Gerhard Jebsen Foundation (to AM)

Apoptosis-Like Death in Bacteria Induced by HAMLET, a Human Milk Lipid-Protein Complex

Background: Apoptosis is the primary means for eliminating unwanted cells in multicellular organisms in order to preserve tissue homeostasis and function. It is characterized by distinct changes in the morphology of the dying cell that are orchestrated by a series of discrete biochemical events. Although there is evidence of primitive forms of programmed cell death also in prokaryotes, no information is available to suggest that prokaryotic death displays mechanistic similarities to the highly regulated programmed death of eukaryotic cells. In this study we compared the characteristics of tumor and bacterial cell death induced by HAMLET, a human milk complex of alpha-lactalbumin and oleic acid. Methodology/Principal Findings: We show that HAMLET-treated bacteria undergo cell death with mechanistic and morphologic similarities to apoptotic death of tumor cells. In Jurkat cells and Streptococcus pneumoniae death was accompanied by apoptosis-like morphology such as cell shrinkage, DNA condensation, and DNA degradation into high molecular weight fragments of similar sizes, detected by field inverse gel electrophoresis. HAMLET was internalized into tumor cells and associated with mitochondria, causing a rapid depolarization of the mitochondrial membrane and bound to and induced depolarization of the pneumococcal membrane with similar kinetic and magnitude as in mitochondria. Membrane depolarization in both systems required calcium transport, and both tumor cells and bacteria were found to require serine protease activity (but not caspase activity) to execute cell death. Conclusions/Significance: Our results suggest that many of the morphological changes and biochemical responses associated with apoptosis are present in prokaryotes. Identifying the mechanisms of bacterial cell death has the potential to reveal novel targets for future antimicrobial therapy and to further our understanding of core activation mechanisms of cell death in eukaryote cells