Optical spectroscopy of rare-earth ions doped KY(WO4)2 thin films

KY(WO4)2 thin films doped with Dy3+, Tb3+, Yb3+, were grown onto KY(WO4)2 substrates using liquid-phase epitaxy. Spectroscopic investigations of the grown layers were performed. Obtained results were compared with spectra given for bulk crystals. Upconversion experiments after direct Yb3+ excitation in Dy3+-Yb3+ and Tb3+-Yb3+ codoped layers will be also presented

Optical and microwave control of resonance fluorescence and squeezing spectra in a polar molecule

A two-level quantum emitter with broken inversion symmetry simultaneously driven by an optical field and a microwave field that couples to the permanent dipole's moment is presented. We focus to a situation where the angular frequency of the microwave field is chosen such that it closely matches the Rabi frequency of the optical field, the so-called Rabi resonance condition. Using a series of unitary transformations we obtain an effective Hamiltonian in the double-dressed basis which results in easily solvable Bloch equations which allow us to derive analytical expressions for the spectrum of the scattered photons. We analyze the steady-state population inversion of the system which shows a distinctive behavior at the Rabi resonance with regard to an ordinary two-level nonpolar system. We show that saturation can be produced even in the case that the optical field is far detuned from the transition frequency, and we demonstrate that this behavior can be controlled through the intensity and the angular frequency of the microwave field. The spectral properties of the scattered photons are analyzed and manifest the emergence of a series of Mollow-like triplets which may be spectrally broadened or narrowed for proper values of the amplitude and/or frequency of the low-frequency field. We also analyze the phase-dependent spectrum which reveals that a significant enhancement or suppression of the squeezing at certain sidebands can be produced. These quantum phenomena are illustrated in a recently synthesized molecular complex with high nonlinear optical response although they can also occur in other quantum systems with broken inversion symmetry

Low-temperature flux growth of sulfates, molybdates, and tungstates of Ca, Sr, and Ba and investigation of doping with Mn 6 +

The growth of undoped and Mn6+-doped molybdates and tungstates of alkali-earth metals and BaSO4 has been investigated. Single crystals were grown by the flux method within the temperature range of 600-475°C, using the ternary NaCl-KCl-CsCl solvent. Sizes of undoped crystals increase within the series tungstates<molybdates<sulfate and, depending on the cation, within the series Ca2+≈Sr2+<Ba2+. The Mn6+ ion tends to be reduced to Mn5+/Mn4+ with time in the chloride solution, but can be partly stabilized by the addition of alkali-metal carbonates or hydroxides. The incorporation of Mn6+ is governed by the coordination of the MnO4 2- tetrahedron in the crystal. No significant doping was found for Ca and Sr compounds and only small amounts of Mn6+ were incorporated into BaMoO4 and BaWO4. Crystals with orthorhombic space group Pnma such as BaSO4 exhibit significantly higher doping levels. The Mn6+ distribution in each crystal varies due to manganese reduction with growth time. Temperature-, time-, and concentration-dependent spectroscopy of BaSO4:Mn6+ was performe

Information processing at the foxa node of the sea urchin endomesoderm specification network

The foxa regulatory gene is of central importance for endoderm specification across Bilateria, and this gene lies at an essential node of the well-characterized sea urchin endomesoderm gene regulatory network (GRN). Here we experimentally dissect the cis-regulatory system that controls the complex pattern of foxa expression in these embryos. Four separate cis-regulatory modules (CRMs) cooperate to control foxa expression in different spatial domains of the endomesoderm, and at different times. A detailed mutational analysis revealed the inputs to each of these cis-regulatory modules. The complex and dynamic expression of foxa is regulated by a combination of repressors, a permissive switch, and multiple activators. A mathematical kinetic model was applied to study the dynamic response of foxa cis-regulatory modules to transient inputs. This study shed light on the mesoderm–endoderm fate decision and provides a functional explanation, in terms of the genomic regulatory code, for the spatial and temporal expression of a key developmental control gene

Spatial reorganization of putaminal dopamine D2-like receptors in cranial and hand dystonia

The putamen has a somatotopic organization of neurons identified by correspondence of firing rates with selected body part movements, as well as by complex, but organized, differential cortical projections onto putamen. In isolated focal dystonia, whole putaminal binding of dopamine D(2)-like receptor radioligands is quantitatively decreased, but it has not been known whether selected parts of the putamen are differentially affected depending upon the body part affected by dystonia. The radioligand [(18)F]spiperone binds predominantly to D(2)-like receptors in striatum. We hypothesized that the spatial location of [(18)F]spiperone binding within the putamen would differ in patients with dystonia limited to the hand versus the face, and we tested that hypothesis using positron emission tomography and magnetic resonance imaging. To address statistical and methodological concerns, we chose a straightforward but robust image analysis method. An automated algorithm located the peak location of [(18)F]spiperone binding within the striatum, relative to a brain atlas, in each of 14 patients with cranial dystonia and 8 patients with hand dystonia. The mean (left and right) |x|, y, and z coordinates of peak striatal binding for each patient were compared between groups by t test. The location of peak [(18)F]spiperone binding within the putamen differed significantly between groups (cranial dystonia z<hand dystonia z, p = 0.016). We conclude that in isolated focal dystonia, dopamine D(2)-like receptors are distributed differently in the putamen depending on the body part manifesting dystonia

Rarity of monodominance in hyperdiverse Amazonian forests.

Tropical forests are known for their high diversity. Yet, forest patches do occur in the tropics where a single tree species is dominant. Such "monodominant" forests are known from all of the main tropical regions. For Amazonia, we sampled the occurrence of monodominance in a massive, basin-wide database of forest-inventory plots from the Amazon Tree Diversity Network (ATDN). Utilizing a simple defining metric of at least half of the trees ≥ 10 cm diameter belonging to one species, we found only a few occurrences of monodominance in Amazonia, and the phenomenon was not significantly linked to previously hypothesized life history traits such wood density, seed mass, ectomycorrhizal associations, or Rhizobium nodulation. In our analysis, coppicing (the formation of sprouts at the base of the tree or on roots) was the only trait significantly linked to monodominance. While at specific locales coppicing or ectomycorrhizal associations may confer a considerable advantage to a tree species and lead to its monodominance, very few species have these traits. Mining of the ATDN dataset suggests that monodominance is quite rare in Amazonia, and may be linked primarily to edaphic factors