Dynamic Analysis Of Male "Extra-high Voice" Using Multi-row Detector Computed Tomography.

OBJECTIVES/HYPOTHESIS: Some people who practice singing on a daily basis may be able to produce a voice higher than the upper limit of the normal range (extra high voice), but there is much regarding the movement of the larynx that remains unknown. We have been conducting dynamic analysis of the larynx using multi-row detection computed tomography (MD-CT) at our university and report herein an analysis of the extra high voice. STUDY DESIGN: Observational. METHODS: Images of a normal male participant capable of extremely high-frequency speech (the highest speech range is C7 [2093 Hz] and the singing application range is up to B5 [988 Hz]) during speech were captured by MD-CT. The acquisition time was 2 seconds, and the rise of the voice from low to high and then to very high tones was recorded. Ten frames per second were analyzed as three-dimensional images. RESULTS: In the fundamental frequency range from A3 to D5 (220-587 Hz), laryngeal elevation movements were observed as the voice rose in pitch. However, posterior upward displacement of the laryngeal cartilage was observed as the frequency range increased from E5 to B5 (659-988 Hz). CONCLUSIONS: In the E5-B5 range, laryngeal movements were different from those observed in the previous range. MD-CT analysis is useful in the study of this range because it allows visualization of laryngeal movements that are unclear using endoscopy or external examination.

Single microgel degradation governed by heterogeneous nanostructures.

Although the degradation of colloidal particles is one of the most attractive phenomena in the field of biological and environmental science, the degradation mechanism of single particles remains to be elucidated. In this study, in order to clarify the impact of the structure of a single particle on the oxidative degradation processes, thermoresponsive colloidal particles with chemical cleavage points were synthesized as a model, and their degradation behavior was evaluated using high-speed atomic force microscopy (HS-AFM) as well as conventional scattering techniques. The real-time observation of single-particle degradation revealed that the degradation behavior of microgels is governed by their inhomogeneous nanostructure, which originates from the polymerization method and their hydrophilicity. Our findings can be expected to advance the design of carriers for drug-delivery and the understanding of the formation processes of micro (nano)plastics.

Population persistence under two conservation measures: Paradox of habitat protection in a patchy environment.

Anthropogenic modification of natural habitats is a growing threat to biodiversity and ecosystem services. The protection of biospecies has become increasingly important. Here, we pay attention to a single species as a conservation target. The species has three processes: reproduction, death and movement. Two different measures of habitat protection are introduced. One is partial protection in a single habitat (patch); the mortality rate of the species is reduced inside a rectangular area. The other is patch protection in a two-patch system, where only the mortality rate in a particular patch is reduced. For the one-patch system, we carry out computer simulations of a stochastic cellular automaton for a "contact process". Individual movements follow random walking. For the two-patch system, we assume an individual migrates into the empty cell in the destination patch. The reaction-diffusion equation (RDE) is derived, whereby the recently developed "swapping migration" is used. It is found that both measures are mostly effective for population persistence. However, comparing the results of the two measures revealed different behaviors. ⅰ) In the case of the one-patch system, the steady-state densities in protected areas are always higher than those in wild areas. However, in the two-patch system, we have found a paradox: the densities in protected areas can be lower than those in wild areas. ⅱ) In the two-patch system, we have found another paradox: the total density in both patches can be lower, even though the proportion of the protected area is larger. Both paradoxes clearly occur for the RDE with swapping migration.

Microbial mutualism promoting the coexistence of competing species: Double-layer model for two competing hosts and one microbial species.

Gause's law of competitive exclusion holds that the coexistence of competing species is extremely unlikely when niches are not differentiated. This law is supported by many mathematical studies, yet the coexistence of competing species is nearly ubiquitous in real ecosystems. We pay attention to the fact that plants and animals usually contact with microbial species as mutualistic partners. The activity spaces of host species are different from those of micro-organisms. In the present study, we apply double-layer model to the association of two competing hosts and a microorganism. Two lattices are prepared: one is for hosts, and the other is for microorganism. The basic equation obtained by mean-field theory is an extension of Lotka-Volterra competition model. Both mathematical analysis and numerical simulations reveal that a shared microbial mutualist can permit the coexistence of competing hosts. From the derived condition of coexistence, we believe the microbial mutualism promotes biodiversity in many ecological systems.

Metapopulation model for a prey-predator system: Nonlinear migration due to the finite capacities of patches.

Many species live in spatially separated patches, and individuals can migrate between patches through paths. In real ecosystems, the capacities of patches are finite. If a patch is already occupied by the individuals of some species, then the migration into the patch is impossible. In the present paper, we deal with prey-predator system composed of two patches. Each patch contains a limited number of cells, where the cell is either empty or occupied by an individual of prey or predator. We introduce "swapping migration" defined by the exchange between occupied and empty cells. An individual can migrate, only when there are empty cells in the destination patch. Reaction-migration equations in prey-predator system are presented, where the migration term forms nonlinear function of densities. We numerically solve equilibrium densities, and find that the population dynamics are largely affected by nonlinear migration. Not only extinction points but also the responses to the environmental changes crucially depend on the patch capacities.

Supramolecular assemblies of a nitrogen-embedded buckybowl dimer with C60.

A directly connected azabuckybowl dimer was synthesized via a palladium-catalysed C-H/C-Br coupling. The electron-donating nature of the pyrrolic nitrogen atoms of the azabuckybowl enabled a strong complexation with pristine C60. In the presence of two equivalents of C60, the azabuckybowl dimer formed crystals with a 1 : 2 stoichiometry. Conversely, in diluted solution, complexes with a 1 : 1 stoichiometry of the dimer and C60 were detected predominantly, and these precipitated upon increasing the concentration of C60. Scanning electron microscopy images of the precipitate showed fibre-like aggregates, indicating the formation of supramolecular assemblies with 1D chain structures. A variable-temperature 1H NMR analysis revealed that the precipitate consists of the dimer and C60 in a 1 : 1 ratio.

Azabuckybowl-Based Molecular Tweezers as C60 and C70 Receptors.

We designed and synthesized molecular tweezers consisting of nitrogen-embedded buckybowl subunits. The judicious choice of the covalent linkers modulated their binding strength with C60 or C70 in solution. Titration studies by optical and 1H NMR analyses revealed a 1:1 composition of the resulting complexes. X-ray diffraction analysis elucidated their solid-state structures, in which two azabuckybowl units surround one fullerene molecule. The large association constants stabilize the complexes toward redox reactions and the purification process on silica-gel column chromatography. The linker enabled tuning of the cavity size for binding of fullerenes, achieving complementary fullerene hosts for C60 and C70: the carbazole-bridged dimer preferentially associates with C70 over C60, while the phenanthrene-bridged dimer interacts with C60 more strongly than C70. Electrochemical analysis in combination with density functional theory calculations indicated the existence of intermolecular charge-transfer interactions between the buckybowl units and the fullerenes. Nonlinear optical measurements showed that the two-photon absorption cross sections of the molecular tweezers are enhanced upon association with fullerenes.

Reversible σ-Bond Formation in Bowl-Shaped π-Radical Cations: The Effects of Curved and Planar Structures.

The reversible formation of σ-bonds between organic radicals has been widely investigated. However, reports on the formation of σ-dimers from delocalized π-radical cations are scarce. Herein, we report the reversible σ-dimerization behavior of a bowl-shaped π-radical cation generated from a nitrogen-embedded buckybowl, both in the crystalline state and in solution. The detailed structure of the σ-dimer in the crystalline state was determined by a single-crystal X-ray diffraction analysis. The monomeric radical cation exists predominantly in solution at room temperature, while dimerization of the radical cations occurs through carbon-carbon σ-bond formation upon reducing the temperature. 1H NMR and optical spectroscopy measurements confirmed the formation of a σ-dimer at low temperature. Comparative studies with a similar yet planar π-conjugated system suggested that the curved structure of the bowl-shaped π-radical cation facilitates the σ-dimerization at one of the internal sp2-hybridized carbon atoms. This trend was also observed for the nucleophilic addition reaction of methanol to the π-radical cations. The methoxylation reaction proceeded only for the curved π-radical cation. Theoretical calculations revealed that the large relief of structural strain at the α-carbon atom during the dimerization or nucleophilic addition reactions accelerated the bond formation at the internal carbon atom of the curved radical cation.

Impact of biology knowledge on the conservation and management of large pelagic sharks.

Population growth rate, which depends on several biological parameters, is valuable information for the conservation and management of pelagic sharks, such as blue and shortfin mako sharks. However, reported biological parameters for estimating the population growth rates of these sharks differ by sex and display large variability. To estimate the appropriate population growth rate and clarify relationships between growth rate and relevant biological parameters, we developed a two-sex age-structured matrix population model and estimated the population growth rate using combinations of biological parameters. We addressed elasticity analysis and clarified the population growth rate sensitivity. For the blue shark, the estimated median population growth rate was 0.384 with a range of minimum and maximum values of 0.195-0.533, whereas those values of the shortfin mako shark were 0.102 and 0.007-0.318, respectively. The maturity age of male sharks had the largest impact for blue sharks, whereas that of female sharks had the largest impact for shortfin mako sharks. Hypotheses for the survival process of sharks also had a large impact on the population growth rate estimation. Both shark maturity age and survival rate were based on ageing validation data, indicating the importance of validating the quality of these data for the conservation and management of large pelagic sharks.

Nitrogen-embedded buckybowl and its assembly with C60.

Curved π-conjugated molecules have attracted considerable interest because of the unique properties originating from their curved π surface. However, the synthesis of such distorted molecules requires harsh conditions, which hamper easy access to heteroatom-containing curved π systems. Here we report the synthesis of a π-extended azacorannulene with nitrogen in its centre. The oxidation of 9-aminophenanthrene provides tetrabenzocarbazole, which is converted to the azabuckybowl through palladium-catalysed intramolecular coupling. The electron-donating nature and curved π surface of the azabuckybowl enable its tight association with C60 in solution and solid states. High charge mobility is observed for the azabuckybowl/C60 assembly. This compound may be of interest in the fields of curved π systems as fullerene hosts, anisotropic π donors and precursors to nitrogen-containing nanocarbon materials.

Synthesis of diazo-bridged BODIPY dimer and tetramer by oxidative coupling of ß-amino-substituted BODIPYs.

A diazo-bridged BODIPY dimer and tetramer were prepared by the oxidative coupling reaction of ß-amino-substituted BODIPYs. The structure of the dimer was elucidated by X-ray diffraction analysis, showing its coplanar orientation of two BODIPY units. Effective extension of π-conjugation was confirmed by optical and electrochemical investigations.

Oxidation of 2-amino-substituted BODIPYs providing pyrazine-fused BODIPY trimers.

Oxidation of 2-amino-substituted BODIPYs afforded BODIPY trimers in a one-step operation. The trimer consists of a pyrazine-fused BODIPY dimer to which one BODIPY unit is connected through an NH linkage. Effective expansion of π-conjugation over the fused dimer was observed in optical and electrochemical measurements.