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Axisymmetric ring systems can be identified from the new catalog of collisional ring galaxies by Madore et al. in 2009. These are O-type-like collisional ring galaxies. Head-on collisions by dwarf galaxies moving along the symmetric axis were performed through N-body simulations to address their origins. It was found that the simulations with smaller initial relative velocities between two galaxies, or in the cases with heavier dwarf galaxies, could produce rings with higher density contrasts. There is more than one generation of rings in one collision and the lifetime of any generation of rings is about one dynamical time. It was concluded that head-on penetrations could explain these O-type-like ring galaxies identified from the new catalog by Madore et al. in 2009, and the simulated rings resembling the observational O-type-like collisional rings are those at the early stage of one of the ring generations. [ABSTRACT FROM AUTHOR]

Background: Fork head box M1 (FoxM1) is a proliferation-associated transcription factor essential for cell cycle progression. Numerous studies have documented that FoxM1 has multiple functions in tumorigenesis and its elevated levels are frequently associated with cancer progression. The present study was conducted to investigate the expression of FoxM1 and its prognostic significance in clear cell renal cell carcinoma (ccRCC). Meanwhile, the function of FoxM1 in human ccRCC was further investigated in cell culture models. Methods: Real-time quantitative PCR, western blot and immunohistochemistry were used to explore FoxM1 expression in ccRCC cell lines and primary ccRCC clinical specimens. FoxM1 expression was knocked down by small interfering RNA (siRNA) in Caki-1 and 786-O cells; proliferation, colony formation, cell cycle, migration, invasion, and angiogenesis were assayed. Results: FoxM1 expression was up-regulated in the majority of the ccRCC clinical tissue specimens at both mRNA and protein levels. Clinic pathological analysis showed that FoxM1 expression was significantly correlated with primary tumor stage (P <0.001), lymph node metastasis (P = 0.01), distant metastasis (P = 0.01), TNM stage (P < 0.001) and histological grade (P = 0.003). The Kaplan-Meier survival curves revealed that high FoxM1 expression was associated with poor prognosis in ccRCC patients (P < 0.001). FoxM1 expression was an independent prognostic marker of overall ccRCC patient survival in a multivariate analysis (P = 0.008). Experimentally, we found that down-regulation of FoxM1 inhibited cell proliferation and induced cell cycle arrest with reduced expression of cyclin B1, cyclin D1, and Cdk2, and increased expression of p21 and p27. Also, down-regulation of FoxM1 reduced expression and activity of matrix metalloproteinase-2 (MMP-2), MMP-9 and vascular endothelial growth factor (VEGF), resulting in the inhibition of migration, invasion, and angiogenesis. Conclusions: These results suggest that FoxM1 expression is likely to play important roles in ccRCC development and progression, and that FoxM1 is a prognostic biomarker and a promising therapeutic target for ccRCC. [ABSTRACT FROM AUTHOR]

The article presents a comparative study which explored the juvenile growth and reproduction characteristics of Pomacea scalaris and P. canaliculata, the invasive apple snails species. The study performed polynomial regressions and t-tests. Results show that P. scalaris' inferior growth performance and smaller hatching size may have influenced its distribution in Taiwan.

Abstract: In order to understand the heat transfer characteristics of molten salt and testify the validity of the well-known empirical convective heat transfer correlations, an experimental study on turbulent convective heat transfer with molten salt in a circular tube was conducted in this paper. Molten salt circulations were realized and operated in a specially designed system over 1000 h. The flow rates and temperatures of molten salt and mineral oil at the inlet and outlet in the test section were measured and the average forced convective heat transfer coefficients of molten salt were determined by least-squares method. Finally, heat transfer correlations of turbulent flow with molten salt in a circular tube were obtained. Good agreement was observed between the experimental data of molten salt and the existing well-known correlations. The experimental data of molten salt in the present work are consistent with experimental results reported by different references in a wide range of Prandtl numbers from 0.7 to 59.9. [Copyright &y& Elsevier]

Abstract: In order to understand the heat transfer characteristics of molten salt and testify the validity of the well-known empirical convective heat transfer correlations, experimental study on transition convective heat transfer with molten salt in a circular tube was conducted. Molten salt circulations were realized and operated in a specially designed system over 1000h. The average forced convective heat transfer coefficients of molten salt were determined by least-squares method based on the measured data of flow rates and temperatures. Finally, a heat transfer correlation of transition flow with molten salt in a circular tube was obtained and good agreement was observed between the experimental data of molten salt and the well-known correlations presented by Hausen and Gnielinski, respectively. [Copyright &y& Elsevier]

The spindle is essential for chromosome segregation during meiosis, but the molecular mechanism of meiotic spindle organization in higher plants is still not well understood. Here, we report on the identification and characterization of a plant-specific protein, MULTIPOLAR SPINDLE 1 (MPS1), which is involved in spindle organization in meiocytes of Arabidopsis thaliana. The homozygous mps1 mutant exhibits male and female sterility. Light microscopy showed that mps1 mutants produced multiple uneven spores during anther development, most of which aborted in later stages. Cytological analysis showed that chromosome segregation was abnormal in mps1 meiocytes. Immunolocalization showed unequal bipolar or multipolar spindles in mps1 meiocytes, which indicated that aberrant spindles resulted in disordered chromosome segregation. MPS1 encodes a 377-amino-acid protein with putative coiled-coil motifs. In situ hybridization analysis showed that MPS1 is strongly expressed in meiocytes. [ABSTRACT FROM AUTHOR]

Wind driven raindrop tracking is used to investigate the microscale redistribution of wind driven rainfalls in street canopies by combining a Eulerian wind flow model and a Lagrangian raindrop tracking model. The former conducts large eddy simulations of the turbulent flows in street canopies, and the latter performs raindrop trajectory calculations by releasing a large number of raindrops into the computational domain. The wind speed model is verified with available wind tunnel measurement. Twenty sets of simulations are carried out for various building configurations and driving rain angles. The simulated results show that the trajectories of smaller raindrops are more slanting and more influenced by the multibuilding perturbed flow field. Impingement of raindrops on the building envelope increases from bottom to top. The height of the front building is a significant factor affecting wind driven rain redistribution. Distinct nonuniform spatial rainfall distributions are found for scenarios with high building configurations and low driving rain angles. The simulated results are further integrated to assess the effect of real raindrop size distributions by weighing the volumetric fraction of a range of drop sizes. There is about 10 percent variation in spatial extent of street canopies. An overall 5 to 17.4 percent increase of the rainfall amount in the upwind zone is observed. [ABSTRACT FROM AUTHOR]

N-body simulations of galactic collisions are employed to investigate the formation of elliptical rings in disk galaxies. The relative inclination between disk and dwarf galaxies is studied with a fine step of 5°. It is confirmed that the eccentricity of elliptical rings is linearly proportional to the inclination angle. Deriving from the simulational results, an analytic formula that expresses the eccentricity as a function of time and inclination angle is obtained. This formula will be useful for the interpretation of observations of ring systems, and therefore reveals the merging histories of galaxies. [ABSTRACT FROM AUTHOR]

A particulate matter (PM) transport model is developed to investigate coarse PM (PM10), fine PM (PM2.5), and very fine PM (PM1) transport mechanisms in urban street canopies under low-wind conditions. Two common building layouts (i.e., the open and staggered street canopies) are considered. Large eddy simulations with the subgrid-scale stress model and the wall function are used to simulate urban streetcanopy flows. The Lagrangian particle tracking approach, considering the effects of the drag force, gravitational force, Brownian motion, and Saffman lift force on particles is adopted to study PM transport behaviors in urban street canopies. The box counting method is used to calculate the canopy-averaged PM10/PM2.5/PM1 mass concentrations and transport mechanisms at each tracking time. The simulated results show that the removal efficiencies of PM10, PM2.5, and PM1 in the open street canopies are all better than those in the staggered street canopies. As a result, the open street canopies having higher PM removal ability lead to a swifter shift of the particle size distributions towards smaller size and less deviation than the staggered street canopies. The major particle removal mechanism for the open street canopies is particle escape, whereas wall deposition plays the most important role for the staggered street canopies. In comparison with the effectiveness of PM10/PM2.5/PM1 removal for both building layouts, PM10 particles are easier to overcome the root mean square vertical turbulent velocity and need less time to deposit. Fine particles would follow airflow paths and need longer time to deposit. As a result, PM2.5 and PM1 are more difficult to be removed than PM10. [ABSTRACT FROM AUTHOR]

Fungal diversity and community composition are mainly related to soil and vegetation factors. However, the relative contribution of the different drivers remains largely unexplored, especially in subtropical forest ecosystems. We studied the fungal diversity and community composition of soils sampled from 12 comparative study plots representing three forest age classes (Young: 10-40 yrs; Medium: 40-80 yrs; Old: ≥80 yrs) in Gutianshan National Nature Reserve in South-eastern China. Soil fungal communities were assessed employing ITS rDNA pyrotag sequencing. Members of Basidiomycota and Ascomycota dominated the fungal community, with 22 putative ectomycorrhizal fungal families, where Russulaceae and Thelephoraceae were the most abundant taxa. Analysis of similarity showed that the fungal community composition significantly differed among the three forest age classes. Forest age class, elevation of the study plots, and soil organic carbon (SOC) were the most important factors shaping the fungal community composition. We found a significant correlation between plant and fungal communities at different taxonomic and functional group levels, including a strong relationship between ectomycorrhizal fungal and non-ectomycorrhizal plant communities. Our results suggest that in subtropical forests, plant species community composition is the main driver of the soil fungal diversity and community composition.