• Title/Summary/Keyword: tilted beta distribution

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Tilted beta regression and beta-binomial regression models: Mean and variance modeling

  • Edilberto Cepeda-Cuervo
    • Communications for Statistical Applications and Methods
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    • v.31 no.3
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    • pp.263-277
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    • 2024
  • This paper proposes new parameterizations of the tilted beta binomial distribution, obtained from the combination of the binomial distribution and the tilted beta distribution, where the beta component of the mixture is parameterized as a function of their mean and variance. These new parameterized distributions include as particular cases the beta rectangular binomial and the beta binomial distributions. After that, we propose new linear regression models to deal with overdispersed binomial datasets. These new models are defined from the proposed new parameterization of the tilted beta binomial distribution, and assume regression structures for the mean and variance parameters. These new linear regression models are fitted by applying Bayesian methods and using the OpenBUGS software. The proposed regression models are fitted to a school absenteeism dataset and to the seeds germination rate according to the type seed and root.

Low Rayleigh Number Thermal Convection Between Two Horizontal Plates with Sinusoidal Temperature Distributions (정현적인 온도 분포를 갖는 두 수평 평판 사이에서의 작은 Rayleigh 수 열 대류)

  • 유주식;김용진
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.13 no.3
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    • pp.145-152
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    • 2001
  • Low Rayleigh number thermal convection in a fluid layer confined between two-infinite horizontal walls kept at spatially sinusoidal temperature distributions, T_L=T_m+\Delta T\sin \kappax,\;T_U=T_m+\Delta T\sin(\kappax-\beta)$, is theoretically investigated by a regular perturbation expansion method. For small wave numbers, an upright cell is formed between the two walls at $\beta$=0. The cell is tilted, as the phase difference increases, and a flow with tow counter-rotating eddies occurs at $\beta=\pi$. when the wave number is large, isolated eddies are formed near the lower and upper walls, for all the phase differences. There exists a wave number at which maximum heat transfer rate at the walls occurs, at each of the phase differences. And the wave number increases with increase of the phase difference. for a fixed wave number, the heat transfer rate decrease with increase of the phase difference.

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Composition and Distribution of Phytoplankton with Size Fraction Results at Southwestern East/Japan Sea

  • Park, Mi-Ok
    • Ocean Science Journal
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    • v.41 no.4
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    • pp.301-313
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    • 2006
  • Abundance and distribution of phytoplankton in seawater at southwestern East/Japan Sea near Gampo were investigated by HPLC analysis of photosynthetic pigments during summer of 1999. Detected photosynthetic pigments were chlorophyll a, b, $c_{1+2}$ (Chl a, Chl b, Chl $c_{1+2}$), fucoxanthin (Fuco), prasinoxanthin (Pras), zeaxanthin (Zea), 19'-butanoyloxyfucoxanthin (But-fuco) and beta-carotene (B-Car). Major carotenoid was fucoxanthin (bacillariophyte) and minor carotenoids were Pras (prasinophyte), Zea (cyanophyte) and But-fuco (chrysophyte). Chl a concentrations were in the range of $0.16-8.3\;{\mu}g/land$ subsurface chlorophyll maxima were observed at 0-10m at inshore and 30-50 m at offshore. Thermocline and nutricline tilted to the offshore direction showed a mild upwelling condition. Results from size-fraction showed that contribution from nano+picoplankton at Chl a maximum layer was increased from 18% at inshore to 69% at offshore on average. The maximum contribution from nano+picoplankton was found as 87% at St. E4. It was noteworthy that contribution from nano+picoplanktonic crysophytes and green algae to total biomass of phytoplankton was significant at offshore. Satellite images of sea surface temperature indicated that an extensive area of the East/Japan Sea showed lower temperature ($<18\;^{\circ}C$) but the enhanced Chi a patch was confined to a narrow coastal region in summer, 1999. Exceptionally high flux of low saline water from the Korea/Tsushima Strait seemed to make upwelling weak in summer of 1999 in the study area. Results of comparisons among Chi a from SeaWiFS, HPLC and fluorometric analysis showed that presence of Chi b cause underestimation of Chi a about 30% by fluorometric analysis but overestimation by satellite data about 30-75% compared to HPLC data.

Cleavage Pattern of Urechis unicinctus Eggs in Vitro Fertilization (인공수정에 의한 Urechis unicinctus 난자의 난할형식)

  • Shin, Kil-Sang;Lee, Dae-Hee;Ko, Tae-Young
    • Applied Microscopy
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    • v.34 no.1
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    • pp.71-81
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    • 2004
  • When U. unicinctus mature oocytes were fertilized in vitro, germinal vesicle breakdown (GVBD) and meioses occurred and the zygotes entered cleavage stage. A modified pattern of spiral cleavages, suggestively based on behavior of mitotic spindles, have been observed in this work. The first and second cleavages were meridional and the third was equatorial, and then followed by repetitions of meridional-equatorial cleavage. The cleavage of the isolecithal egg were equal and holoblastic and its patterns were spiral. The anti-${\alpha}-,-{\beta}$- tubulin reactions and confocal microscopy revealed mitotic apparates tilted obliquely at each mitosis causing oblique displacements of the blastomeres. Despite isolecithal distribution of yolk, this observations implicated that tilting of mitotic apparates induced spiral cleavage and the displacements of blastomeres. However, these features would not be the typical spiral cleavage, but represented a modified pattern of known Spiralian s in the sense of the equal cleavage. During the first cleavage, heart-shaped eggs have been produced. Electron microscopies exhibited the first cleavage furrow extended with its membranous structure deeply into the cytoplasm. Contractile ring has not been observed.