• Title/Summary/Keyword: Tau

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Potential of River Bottom and Bank Erosion for River Restoration after Dam Slit in the Mountain Stream

  • Kang, Ji-Hyun;So, Kazama
    • Proceedings of the Korea Water Resources Association Conference
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    • 2011.05a
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    • pp.46-46
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    • 2011
  • Severe sediment erosion during floods occur disaster and economic losses, but general sediment erosion is basic mechanism to move sediment from upstream to downstream river. In addition, it is important process to change river form. Check dam, which is constructed in mountain stream, play a vital role such as control of sudden debris flow, but it has negative aspects to river ecosystem. Now a day, check dam of open type is an alternative plan to recover river biological diversity and ecosystem through sediment transport while maintaining the function of disaster control. The purpose of this paper is to verify sediment erosion progress of river bottom and bank as first step for river restoration after dam slit by cross-sectional shear stress and critical shear stress. Study area is upstream reach of slit check dam in mountain stream, named Wasada, in Japan. The check dam was slit with two passages in August, 2010. The transects were surveyed for four upstream cross-sections, 7.4 m, 34 m, 86 m, and 150 m distance from dam in October 2010. Sediment size was surveyed at river bottom and bank. Sediment of cobble size was found at the wetted bottom, and small size particles of sand to medium gravel composed river bank. Discharge was $2.5\;m^3/s$ and bottom slope was 0.027 m/m. Excess shear stress (${\tau}_{ex}$) was calculated for hydraulic erosion by subtracting the values of critical shear stress (${\tau}_{c}$) from the value of shear stress (${\tau}$) at river bottom and bank (${\tau}_{ex}=\tau-{\tau}_c$). Shear stress of river bottom (${\tau}_{bottom}$) was calculated using the cross-sectional shear stress, and bank shear stress (${\tau}_{bank}$) was calculated from the method of Flintham and Carling (1988). $${\tau}_{bank}={\tau}^*SF_{bank}((B+P_{bed})/(2^*P_{bank}))$$ where $SF_{bank}=1.77(P_{bed}/p_{bank}+1.5)^{-1.4}$, B is the water surface width, $P_{bed}$ and $P_{bank}$ are wetted parameter of the bed and bank. Estimated values for ${\tau}_{bottom}$ for a flow of $2.5\;m^3/s$ were lower as 25.0 (7.5 m cross-section), 25.7 (34 m), 21.3 (86 m) and 19.8 (150 m), in N/$m^2$, than critical shear stress (${\tau}_c=62.1\;N/m^2$) with cobble of 64 mm. The values were insufficient to erode cobble sediment. In contrast, even if the values of ${\tau}_{bank}$ were lower than the values for ${\tau}_{bottom}$ as 18.7 (7.5 m), 19.3 (34 m), 16.1 (86 m) and 14.7 (150 m), in N/$m^2$, excess shear stresses were calculated at the three cross-sections of 7.5 m, 34 m, and 86 m distances compare with ${\tau}_c$ is 15.5 N/$m^2$ of 16mm gravel. Bank shear stresses were sufficient for erosion of the medium gravel to sand. Therefore there is potential to erode lateral bank than downward erosion in a flow of $2.5\;m^3/s$. Undercutting of the wetted bank can causes bank scour or collapse, therefore this channel has potential to become wider at the same time. This research is about a potential of sediment erosion, and the result could not verify with real data. Therefore it need next step for verification. In addition an erosion mechanism for river restoration is not simple because discharge distribution is variable by snow-melting or rainy season, and a function for disaster control will recover by big precipitation event. Therefore it needs to consider the relationship between continuous discharge change and sediment erosion.

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The Effects of Rotational Correlation Time of Paramagnetic Contrast Agents on Relaxation Enhancement: Partial Binding to Macromolecules (거대분자에 부분적으로 결합한 상자성 자기공명 조영제의 회전속도가 이완증강에 미치는 영향)

  • 장용민
    • Investigative Magnetic Resonance Imaging
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    • v.3 no.2
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    • pp.159-166
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    • 1999
  • Purpose : To evaluate the effect of rotational correlation time (${\tau}_R$) and the possible related changes of other parameters, ${\tau}_M,{\;}{\tau}_S,{\;}and{\;}(\tau}_V$ of gadolinium (Gd) chelate on T1 relaxation enhancement in two pool model. Materials and Methods : The NMRD (Nuclear Magnetic Relaxation Dispersion) profiles were simulated from 0.02 MHz to 800 MHz proton Larmor frequency for different values of rotational correlation times based on Solomon-Bloembergen equation for inner-sphere relaxation enhancement. To include both unbound pool (pool A) and bound pool (pool B), the relaxivity was divided by contribution from unbound pool and bound pool. The rotational correlation time for pool A was fixed at the value of 0.1 ns, which is a typical value for low molecular weight complexes such as Gd-DTPA in solution and ${\tau}_R$ for pool B was changed from 0.1 ns to 20 ns to allow the slower rotation by binding to macromolecule. The fractional factor of was also adjusted from 0 to 1.0 to simulate different binding ratios to macromolecule. Since the binding of Gd-chelate to macromolecule cab alter the electronic environment of Gd ion and also the degree of bulk water access to hydration site of Gd-chelate, the effects of these parameters were also included. Results : The result shows that low field profiles, ranged from 0.02 to 40 MHz, and dominated by contribution from bound pool, which is bound to macromolecule regardless of binding ratios. In addition, as more Gd-chelate bound to macromolecule, sharp increase of relaxivity at higher field occurs. The NMRD profiles for different values of ${\tau}_S$ show the enormous increase of low field profile whereas relaxivity at high field is not affected by ${\tau}_S$. On the other hand, the change in ${\tau}$V does not affect low field profile but strongly in fluences on both inflection fie이 and the maximum relaxivity value. The results shows a fluences on both inflection field and the maximum relaxivity value. The results shows a parabolic dependence of relaxivity on ${\tau}_M$. Conclusion : Binding of Gd-chelate to a macromolecule causes slower rotational tumbling of Gd-chelate and would result in relaxation enhancement, especially in clinical imaging field. However, binding to macromolecule can change water enchange rate (${\tau}_M$) and electronic relaxation ($T_le$) vis structural deformation of electron environment and the access of bulk water to hydration site of metal-chelate. The clinical utilities of Gd-chelate bound to macromolecule are the less dose requirement, the tissue specificity, and the better perfusion and intravascular agents.

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Laboratory Study on the Settling Properties of Silty Mud (실트질 점토의 심강(沈降) 특성(特性)에 관한 연구)

  • Kim, Cha Kyum;Lee, Jong Sup
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.11 no.3
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    • pp.85-93
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    • 1991
  • To investigate the effect of the initial sediment concentration ($C_o$) and bed shear stress (${\tau}_b$) on the settling properties of silty mud, deposition experiments were conducted in a recirculating flume using silty mud sediment taken from the Youngkwang coast which is located in the eastern Yellow Sea. The relative concentration, $C/C_o$ (C=depth averaged concentration), and the relative equilibrium concentration, $C_{eq}/C_o$ ($C_{eq}$=depth averaged concentration in the equilibrium state), have been found to depend much more strongly on the bed shear stress than initial concentration, and to increase with increasing bed shear stress. The minimum value. ${\tau}_{bmin}$, and maximum value. ${\tau}_{bmax}$, of critical bed shear stress for deposition of the Youngkwang sediment were deduced to be $0.017N/m^2$ and $1.25N/m^2$, respectively, and these values depend strongly on the properties of sediment (grain size and mineralogy). Formulas for the relative concentration and apparent median settling velocity in the range of ${\tau}_b{\geq}{\tau}_{bmin}$ were deduced. The apparent median settling velocity was found to depend much more strongly on the bed shear stress than the initial concentration and to decrease exponentially with increasing bed shear stress.

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RECURRENCE RELATIONS FOR QUOTIENT MOMENTS OF THE PARETO DISTRIBUTION BY RECORD VALUES

  • Lee, Min-Young;Chang, Se-Kyung
    • The Pure and Applied Mathematics
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    • v.11 no.1
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    • pp.97-102
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    • 2004
  • In this paper we establish some recurrence relations satisfied by quotient moments of upper record values from the Pareto distribution. Let {$X_n,n\qeq1$}be a sequence of independent and identically distributed random variables with a common continuous distribution function(cdf) F($chi$) and probability density function(pdf) f($chi$). Let $Y_n\;=\;mas{X_1,X_2,...,X_n}$ for $ngeq1$. We say $X_{j}$ is an upper record value of {$X_{n},n\geq1$}, if $Y_{j}$$Y_{j-1}$,j>1. The indices at which the upper record values occur are given by the record times ${u( n)}n,\geq1$, where u(n) = min{j|j >u(n-l), $X_{j}$$X_{u(n-1)}$,n\qeq2$ and u(l) = 1. Suppose $X{\epsilon}PAR(\frac{1}{\beta},\frac{1}{\beta}$ then E$(\frac{{X^\tau}}_{u(m)}}{{X^{s+1}}_{u(n)})\;=\;\frac{1}{s}E$ E$(\frac{{X^\tau}}_{u(m)}{{X^s}_{u(n-1)}})$ - $\frac{(1+\betas)}{s}E(\frac{{X^\tau}_{u(m)}}{{X^s}_{u(n)}}$ and E$(\frac{{X^{\tau+1}}_{u(m)}}{{X^s}_{u(n)}})$ = $\frac{1}{(r+1)\beta}$ [E$(\frac{{X^{\tau+1}}}_u(m)}{{X^s}_{u(n-1)}})$ - E$(\frac{{X^{\tau+1}}_u(m)}}{{X^s}_{u(n-1)}})$ - (r+1)E$(\frac{{X^\tau}_{u(m)}}{{X^s}_{u(n)}})$]

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Temperature-dependent Index of Mitotic Interval (${\tau}_0$) for Chromosome Manipulation in Korean Bullhead, Pseudobagrus fulvidraco

  • Lim, Sang Gu;Han, Hyoung Kyun;Gil, Hyun Woo;Park, In-Seok
    • Development and Reproduction
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    • v.16 no.4
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    • pp.321-327
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    • 2012
  • Korean bullhead (Pseudobagrus fulvidraco) was collected from the Kum River areas of Kangkyung-eup, Nonsan city, Chungcheongnam-do, Korea, from April to June, 2012 and was fertilized in order to observe egg development and temperature-related cleavage rates and mitotic intervals (${\tau}_0$). The fertilized eggs were separative, demersal and light yellowish with $1.5{\pm}0.06mm$ in diameter, and did not contain oil globules. The first cleavage stages were 90 min, 80 min, 60 min and 50 min at $21^{\circ}C$, $24^{\circ}C$, $27^{\circ}C$ and $30^{\circ}C$, respectively. At higher temperatures, eggs developed faster and underwent further identical development. For Korean bullhead, ${\tau}_0$ were $33.4{\pm}2.08$ min at $21^{\circ}C$, $31.5{\pm}3.06$ min at $24^{\circ}C$, $28.1{\pm}2.11$ min at $27^{\circ}C$ and $26.4{\pm}3.35$ min at $30^{\circ}C$. There were strong negative correlations between the $\tau_0$ and water temperatures at all points studied (Y=-1.13X+58.15, $R^2$=0.98, n=30, where Y is ${\tau}_0$ and X is temperature). The results obtained in this work will be helpful for chromosome manipulation by use of cleavage frequency data and ${\tau}_0$ data in Korean bullhead.

A Mathematical Analysis of Water Flow Model Using Ohm's Analogy (Ohm의 법측(法測)을 이용(利用)한 물 이동(移動)의 수학적(數學的) 해석(解析))

  • Jung, Yeong-Sang
    • Korean Journal of Soil Science and Fertilizer
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    • v.14 no.1
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    • pp.1-7
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    • 1981
  • A set of equations of a water transport model of the soil-plant system was described as an electrical circuit using the Ohm's analogy assuming that the transpirational pull be the main source of the driving force and the resistance be proportional to the inverse of the hydraulic conductivity of the catenary. The effective root resistance ($\hat{R}_{\tau}$) and the effective soil water potential ($\hat{\psi}_s$)were defined with the solution of the system; $$\hat{\psi}_s-\hat{R}_{\tau}g_{\tau}={\psi}_0$$ and the validity of the solution of the equation was demonstrated with the data obtained from a soybean field. ${\psi}_s$ and $R_{\tau}$ explained more reasonably than the average values taken so far. Therefore, the solution will describe the soil water status and the root resistance in terms of water transport in the soil-plant system.

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Determination of the Temperature-Dependent Index of Mitotic Interval (${\tau}_o$) for Chromosome Manipulation in Far Eastern Catfish Silurus asotus (메기 Silurus asotus 염색체조작을 위한 온도 의존적 체세포분열 간격지수 결정)

  • Park, In-Seok;Im, Jae-Hyun
    • Korean Journal of Ichthyology
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    • v.13 no.1
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    • pp.85-88
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    • 2001
  • Temperature-related cleavage rates and mitotic intervals (${\tau}_o$) in the far eastern catfish Silurus asotus were studied by averaging the duration of the second and third embryonic divisions to establish effective procedures for chromosome manipulations. At higher temperatures eggs developed faster and underwent more asynchronous development. Mitotic intervals for far eastern catfish were $21.5{\pm}1.4$ min at $22^{\circ}C$, $18.5{\pm}1.2$ min at $24^{\circ}C$, and $14.0{\pm}2.1$ min at $26^{\circ}C$. There was a strong negative correlation between ${\tau}_o$ and water temperature (Y=-1.85X+21.9, $R^2=0.9868$, where Y is ${\tau}_o$ and X is temperature).

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Neural Transdifferentiation: MAPTau Gene Expression in Breast Cancer Cells

  • Lara-Padilla, E;Miliar-Garcia, A;Gomez-Lopez, M;Romero-Morelos, P;Bazan-Mendez, CI;Alfaro-Rodriguez, A;Anaya-Ruiz, M;Callender, K;Carlos, A;Bandala, C
    • Asian Pacific Journal of Cancer Prevention
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    • v.17 no.4
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    • pp.1967-1971
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    • 2016
  • Background: In tumor cells, aberrant differentiation programs have been described. Several neuronal proteins have been found associated with morphological neuronal-glial changes in breast cancer (BCa). These neuronal proteins have been related to mechanisms that are involved in carcinogenesis; however, this regulation is not well understood. Microtubule-associated protein-tau (MAP-Tau) has been describing in BCa but not its variants. This finding could partly explain the neuronal-glial morphology of BCa cells. Our aim was to determine mRNA expression of MAP-tau variants 2, 4 and 6 in breast cancer cell lines. Materials and Methods: Cultured cell lines MCF-10A, MDA-MB-231, SKBR3 and T47D were observed under phase-contrast microscopy for neural morphology and analyzed for gene expression of MAP-Tau transcript variants 2, 4 and 6 by real-time PCR. Results: Regarding morphology like neural/glial cells, T47D line shown more cells with these features than MDA-MB-231 and SKBR. In another hand, we found much greater mRNA expression of MAP-Tau transcript variants 2, and to a lesser extent 4 and 6, in T47D cells than the other lines. In conclusion, regulation of MAP-Tau could bring about changes in cytoskeleton, cell morphology and motility; these findings cast further light on neuronal transdifferentiation in BCa.

The Effects of Transcranial Electric Stimulation and Cognition Reinforcement Training on the Expression of Tau Protein in Alzheimer's Disease Rat Models

  • Ryu, Sung Hoon;Min, Kyung Ok;Sim, Ki Cheol;Kim, Gi Do;Kim, Gye Yeop
    • Journal of International Academy of Physical Therapy Research
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    • v.4 no.1
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    • pp.479-487
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    • 2013
  • This study is intended to examine the tDCS and Morris Water maze training in Alzheimer's disease(AD) rats on Tau protein expression. Experiment groups were divided into four groups and assigned 16 rats to each group. Group I was a control group(AD induced by scopolamine); Group II was a experimental control group(AD injured by scopolamine and treatment tacrine); Group III was a group of tDCS application after AD injured by scopolamine; Group IV was a group of morris water maze training after AD injured by scopolamine. In cognition test, the outcome of group II was significantly lower than the groups(p<.001). and group III, IV were significantly low result at 14 days(p<.05). In histological finding, the experimental groups were destroy of micro vessels and finding of cell atropy and swelling. Group III, IV were decreased in degeneration of liver and kidney cells. In immuno- histochemistric response of BDNF and tau protein in hippocampus, BDNF expression of Group II was more increase than the other groups. and increase of BDNF expression was III, IV were higher than group I at 21 days. Tau protein expression of Group II was more decrease than the other groups. and decrease of Tau protein expression was III, IV were lower than group I at 21 days. These result suggest that improved tDCS and morris water maze training after scopolamine induced is associated with dynamically altered expression of BDNF and Tau protein in hippocampus and that is related with cognitive function.

A temperature stable bandpass filter using dieletric-filled stepped impedance resonators (접합된 Stepped impedance resonator를 이용한 온도보상형 유전체 대역통과 필터)

  • Lim, Sang-Kyu;Kim, Jun-Chul;Kim, Duck-Hwan;Ha, Jong-Su;Oh, Chang-Heon;Sim, Hwa-Sup;An, Chul
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.35D no.2
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    • pp.78-85
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    • 1998
  • The design method of a temperature stable bandpass filter using dielectric coaxial resonators of with two dielectric ceramics with opposite signs of temperature coefficient of dielectric constant (${\tau}_{\epsilon}$) to compensate for each other in this method. $MgTiO_3$(${\tau}_{\epsilon}$=+99 ppm/${\circ}C$) as a positive ${\tau}_{\epsilon}$ material and Ba($Zn_{1/3}Nb_{2/3}$)$O_3$(${\tau}_{\epsilon}$=-77ppm/${\circ}C$) as a negative material were selected. The length of a SIR for the temperature stability was calculated according to the design method and the susceptance slope parameter of the SIR was obtained. A temperature stable bandpass filter using dielectric SIR's was designed, simulated and fabricated. The center frequency of this filter was 915 MHz and the pass bandwidth was 20 MHz. Temperature properties of this bandpass filter by simulations were compared with the measured results of the bandpass filter fabricated.

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