14,828 research outputs found
THEORETICAL ANALYSES ON "SPLASH" FORMATION OF COMPETITIVE DIVING
Based upon our work in theoretical analysis and computer simulation of the impact process between diver and water, the purpose of this study was to analyze mechanisms of "splash" formation. The entry technique with palms facing each other was simplified as water entry of a "wedged" object. The entry technique with internal rotation of the arms to form a flat impact surface with the palms was simplified as water entry of a "rectangle". Finally, the water entry with rotation was treated as water entry of a "rotating rectangle", Further mechanical analyses were performed to synthesize "splash" formation mechanisms of these different objects under various impact conditions, and formulate a splash control theory that combines an active impact and a "massaging" motion of water by both hands
Transmission resonance in a composite plasmonic structure
The design, fabrication, and optical properties of a composite plasmonic
structure, a two-dimentional array of split-ring resonators inserted into
periodic square holes of a metal film, have been reported. A new type of
transmission resonance, which makes a significant difference from the
conventional peaks, has been suggested both theoretically and experimentally.
To understand this effect, a mechanism of ring- resonance induced dipole
emission is proposed.Comment: 14 pages, 4 figure
COMPUTER SIMULATION OF "SPLASH CONTROL IN COMPETITIVE DIVING
The purpose of the study was to examine the relationship between the hand pattern and the water splash height during a diver's entry using a computer simulation method. A physical and mathematical model of the impact of a wedged solid object with an ideal fluid was developed. The motion equation (interaction function of solid and fluid) of the solid was established with satisfaction of control functions and initial boundary conditions of the fluid. A finite element method was used to simulate the impact process, with the wedge angle changed from 4" to 80- during the impact. The results suggested that the fluid splash height is inversely proportional to the wedge angle. The "splash control" technique derived from the simulation was also applied in training professional divers and positive results were obtained
Prognostic Outcomes and Risk Factors for Patients with Renal Cell Carcinoma and Venous Tumor Thrombus after Radical Nephrectomy and Thrombectomy: The Prognostic Significance of Venous Tumor Thrombus Level.
IntroductionTo evaluate the prognostic outcomes and risk factors for renal cell carcinoma (RCC) patients with venous tumor thrombus in China.Materials and methodsWe reviewed the clinical information of 169 patients who underwent radical nephrectomy and thrombectomy. Overall and cancer-specific survival rates were analyzed. Univariate and multivariate analyses were used to investigate the potential prognostic factors.ResultsThe median survival time was 63 months. The five-year overall survival and cancer-specific survival rate were 53.6% and 54.4% for all patients. For all patients, significant survival difference was only observed between early (below hepatic vein) and advanced (above hepatic vein) tumor thrombus. However, significant differences existed between both RV/IVC and early/advanced tumor thrombus groups in N0M0 patients. Multivariate analysis demonstrated that higher tumor thrombus level (p = 0.016, RR = 1.58), N (p = 0.013, RR = 2.60), and M (p < 0.001, RR = 4.14) stages and adrenal gland invasion (p = 0.001, RR = 4.91) were the most significant negative prognostic predictors.ConclusionsIn this study, we reported most cases of RCC patients with venous extension in China. We proved that patients with RCC and venous tumor thrombus may have relative promising long-term survival rate, especially those with early tumor thrombus
DEC1, a Basic Helix-Loop-Helix Transcription Factor and a Novel Target Gene of the p53 Family, Mediates p53-dependent Premature Senescence
Cellular senescence plays an important role in tumor suppression. p53 tumor suppressor has been reported to be crucial in cellular senescence. However, the underlying mechanism is poorly understood. In this regard, a cDNA microarray assay was performed to identify p53 targets involved in senescence. Among the many candidates is DEC1, a basic helix-loop-helix transcription factor that has been recently shown to be up-regulated in K-ras-induced premature senescence. However, it is not clear whether DEC1 is capable of inducing senescence. Here, we found that DEC1 is a novel target gene of the p53 family and mediates p53-dependent premature senescence. Specifically, we showed that DEC1 is induced by the p53 family and DNA damage in a p53-dependent manner. We also found that the p53 family proteins bind to, and activate, the promoter of the DEC1 gene. In addition, we showed that overexpression of DEC1 induces G1 arrest and promotes senescence. Moreover, we found that targeting endogenous DEC1 attenuates p53-mediated premature senescence in response to DNA damage. Furthermore, overexpression of DEC1 induces cellular senescence in p53-knockdown cells, albeit to a lesser extent. Finally, we showed that DEC1-induced senescence is p21-independent. Taken together, our data provided strong evidence that DEC1 is one of the effectors downstream of p53 to promote premature senescence
Phylogenetic structure and ecological and evolutionary determinants of species richness
Aim: Site-level species richness is thought to result from both local conditions and species’ evolutionary history, but the nature of the evolutionary effect, and how much it underlies the correlation with current environment, are debated. Although tropical conservatism is a widely used explanatory framework along temperature gradients, it is unclear whether cold tolerance is primarily a threshold effect (e.g. freezing tolerance) or represents a more continuous constraint. Nor is it clear whether cold tolerance is the only major axis of conservatism or whether others, such as water-stress tolerance, are additionally important or trade-off against cold tolerance. We address these questions by testing associated predictions for forest plots distributed across 35° latitude.
Location: China.
Methods: We recorded all trees within 57 0.1-ha plots, generated a phylogeny for the 462 angiosperm species found, and calculated phylogenetic diversity (standardized PD), net relatedness index (NRI) and phylogenetic species variability (PSV) for each plot. We tested the predictions using regression, variance partitioning and structural equation modelling to disentangle potential influences of key climate variables on NRI and PSV, and of all variables on species richness.
Results: Species richness correlated very strongly with minimum temperature, nonlinearly overall but linearly where freezing is absent. The phylogenetic variables also correlated strongly with minimum temperature. While NRI and PSV explained little additional variance in species richness, they accounted for part of the species richness–current climate correlation. Water stress added minimal explanatory power. All these variables showed strong latitudinal gradients.
Main conclusions: Minimum temperature appeared to primarily control tree species richness, via both a threshold-like freezing effect and a linear relationship in climates without freezing. We found no clear signal of water-stress effects. The modelled contribution of evolutionary history is consistent with cold-tolerance conservatism, but could not account for all the species richness–climate relationship
Holographic Ricci dark energy: Interacting model and cosmological constraints
We extend the holographic Ricci dark energy model to include some direct,
non-gravitational interaction between dark energy and dark matter. We consider
three phenomenological forms for the interaction term in the model, namely,
is taken proportional to the Hubble expansion rate and the energy densities
of dark sectors (taken to be , , and , respectively). We obtain a uniform analytical solution to
the three interacting models. Furthermore, we constrain the models by using the
latest observational data, including the 557 Union2 type Ia supernovae data,
the cosmic microwave background anisotropy data from the 7-yr WMAP, and the
baryon acoustic oscillation data from the SDSS. We show that in the interacting
models of the holographic Ricci dark energy, a more reasonable value of
will be obtained, and the observations favor a rather strong
coupling between dark energy and dark matter.Comment: 9 pages, 4 figures; to appear in EPJC; typos corrected, published
versio
- …