A non-linear numerical model for stratified Tsunami waves and its application

A non-linear numerical model is developed for the computation of water level and discharge for the propagation of a unidirectional two-layered tsunami wave. Four governing equations, two for each layer, are derived from Euler’s equations of motion and continuity, assuming a long wave approximation, negligible friction and no interfacial mixing. A numerical model is developed using a staggered Leap-Frog scheme. The developed non- linear model is compared with an existing validated linear model developed earlier by the author for different non-dimensional wave amplitudes. The significance of non-linear terms is discussed. It is found that for simulations of the interface wave amplitude, the effect of non-linear terms is not significant. However, for the simulation of the top surface, the effect of non-linear terms is significant for higher wave amplitudes, and insignificant for lower wave amplitudes. Developed non-linear numerical model is used for the case of a progressive internal wave in an inclined bay. It is found that the effect of an adverse bottom slipe towards the direction of wave propagation is to amplify the wave. This amplification depends on the steepness of slope as well as the ratio of densities of upper layer fluid to lower layer fluid (α). Amplification increases with slope. For higher values of α, amplification of the top and interface surface decreases, which is reasonable. It is also found that even for a 4 percent density difference between upper layer and lower layer, amplification of the top surface will be twenty times higher than amplification in the non-stratified case. The model can be applied confidently to simulate the basic features of different practical problems, similar to those investigated in this study

Exploring Community Preparedness for Complex Disaster: A Case Study in Cilegon (Banten Province in Indonesia)

This study aims at examining how local communities in City of Cilegon (Banten province in Indonesia) consider ‘complex disasters’, and clarifying their subjective perceptions. The present research is considered as the first step in our comprehensive research design beyond a specific case study. The nuclear accidents in the GreatEast Japan Earthquake and the huge flood in Thailand provide lessons that natural disasters can cause catastrophic influences on industries and they generate cascading effects and damages. We define such complicated phenomena as ‘complex disasters’ in this article. Cilegon is potentially exposed to such complex disasters because it has natural disaster risks (among others, the Krakatau volcano sits adjacent to it, andrecalling historical earthquakes and tsunami) and industrial disaster risks (a lot of heavy industry facilities including chemical ones), and these two types of risks can be combined and made reality. A ‘model for the communication of risk’ developed by Rodriguez et al. (2007) is adopted as an analytical framework in this study. The model predicts involvement of many types of actors and can be considered as an adequate framework for our study. This study mainly focused on one industrial gas facility of Pertamina, a state-owned energy company, and its surrounding community (Lebak Gede village) in Cilegon. The qualitative methodologies were used in this study: One focused group discussion (FGD) and three key informant interviews were implemented by the authors. The participants of the FGD were twelve leaders of the neighborhood associations (locally described as ‘RT’ and ‘RW’ in Indonesian acronym) closest to the Pertamina facility (two RW leaders and ten RT leaders). The key informant interviews were separately and additionally conducted with a head of a village, a neighborhoodassociation leader (this leader was different from the FGD participants) and a local forum entity, in order to reinforce observations at the FGD. Our survey observed that involvement of the Indonesia Power, a subsidiary of state-owned electricity company whose facilities adjacent to Petamina’s facility, as one of the industry actors, local governmental agencies and the Indonesian Red Cross. On the other hand, we did not clearly identify any clear involvement of the educational institutions and the mass media, although the model of Rodriguez et al. (2007) estimates their engagement. People in Lebak Gede village have already expected potential threats by large-scale natural disasters. Furthermore, they recognize that such disasters give influence on the industrial facilities and the consequences are catastrophic. Although local residents in Lebak Gede village had a lot of experiences of industrial accidents in the past, these experiences did not initiate a significant mindset change for a more organized preparedness. Instead, they paid larger attentions to floods as their preparedness priority. This study adopted the qualitative method for gathering specific information, but more comprehensive research can contribute to verify preparedness and risk perception on the complex disasters. Although this article selectively dealt with one village (Lebak Gede village) and its preparedness and perception, the findings is to be further clarified in detail for generalizing community preparedness for the complex disasters. Keywords: community, risk perception, natural disaster risk, industrial disaster risk, complex disaster, Cilego

Empirical fragility assessment of buildings affected by the 2011 Great East Japan tsunami using improved statistical models

Tsunamis are destructive natural phenomena which cause extensive damage to the built environment, affecting the livelihoods and economy of the impacted nations. This has been demonstrated by the tragic events of the Indian Ocean tsunami in 2004, or the Great East Japan tsunami in 2011. Following such events, a few studies have attempted to assess the fragility of the existing building inventory by constructing empirical stochastic functions, which relate the damage to a measure of tsunami intensity. However, these studies typically fit a linear statistical model to the available damage data, which are aggregated in bins of similar levels of tsunami intensity. This procedure, however, cannot deal well with aggregated data, low and high damage probabilities, nor does it result in the most realistic representation of the tsunami-induced damage. Deviating from this trend, the present study adopts the more realistic generalised linear models which address the aforementioned disadvantages. The proposed models are fitted to the damage database, containing 178,448 buildings surveyed in the aftermath of the 2011 Japanese tsunami, provided by the Ministry of Land, Infrastructure Transport and Tourism in Japan. In line with the results obtained in previous studies, the fragility curves show that wooden buildings (the dominant construction type in Japan) are the least resistant against tsunami loading. The diagnostics show that taking into account both the building’s construction type and the tsunami flow depth is crucial to the quality of the damage estimation and that these two variables do not act independently. In addition, the diagnostics reveal that tsunami flow depth estimates low levels of damage reasonably well; however, it is not the most representative measure of intensity of the tsunami for high damage states (especially structural damage). Further research using disaggregated damage data and additional explanatory variables is required in order to obtain reliable model estimations of building damage probability

Vertically coupled double quantum dots in magnetic fields

Ground-state and excited-state properties of vertically coupled double quantum dots are studied by exact diagonalization. Magic-number total angular momenta that minimize the total energy are found to reflect a crossover between electron configurations dominated by intra-layer correlation and ones dominated by inter-layer correlation. The position of the crossover is governed by the strength of the inter-layer electron tunneling and magnetic field. The magic numbers should have an observable effect on the far infra-red optical absorption spectrum, since Kohn's theorem does not hold when the confinement potential is different for two dots. This is indeed confirmed here from a numerical calculation that includes Landau level mixing. Our results take full account of the effect of spin degrees of freedom. A key feature is that the total spin, $S$, of the system and the magic-number angular momentum are intimately linked because of strong electron correlation. Thus $S$ jumps hand in hand with the total angular momentum as the magnetic field is varied. One important consequence of this is that the spin blockade (an inhibition of single-electron tunneling) should occur in some magnetic field regions because of a spin selection rule. Owing to the flexibility arising from the presence of both intra-layer and inter-layer correlations, the spin blockade is easier to realize in double dots than in single dots.Comment: to be published in Phys. Rev. B1

Associations of serum folate and holotranscobalamin with cardiometabolic risk factors in rural and urban cameroon

A low intake of fruit and vegetables and a high intake of meat are associated with higher cardiometabolic disease risk; however much prior research has relied on subjective methods for dietary assessment and focused on Western populations. We aimed to investigate the association of blood folate as an objective marker of fruit and vegetable intake and holotranscobalamin (holoTC) as a marker of animal-sourced food intake with cardiometabolic risk factors. We con-ducted a population-based cross-sectional study on 578 adults (mean ± SD age = 38.2 ± 8.6 years; 64% women). The primary outcome was a continuous metabolic syndrome score. The median serum folate was 12.9 (IQR: 8.6–20.5) nmol/L and the mean holoTC was 75 (SD: 34.3) pmol/L. Rural residents demonstrated higher serum folate concentrations (15.9 (9.8–25.9) nmol/L) than urban residents (11.3 (7.9–15.8) nmol/L), but lower holoTC concentrations (rural: 69.8 (32.9) pmol/L; urban: 79.8 (34.9)) pmol/L, p < 0.001 for both comparisons. There was an inverse association between serum folate and metabolic syndrome score by −0.20 in the z-score (95% CI, −0.38 to −0.02) per 10.8 (1 SD) of folate) in a model adjusted for socio-demographic factors, smoking status, alcohol intake, BMI, and physical activity. HoloTC was positively associated with the metabolic syndrome score in unadjusted analysis (0.33 (95% CI, 0.10 to 0.56)) but became non-significant (0.17 (−0.05 to 0.39)) after adjusting for socio-demographic and behavioural characteristics. In conclusion, serum folate and holoTC were associated with the metabolic syndrome score in opposite directions. The positive association between serum holoTC and the metabolic syndrome score was partly dependent on sociodemographic characteristics. These findings suggest that, based on these biomarkers reflecting dietary intakes, public health approaches promoting a higher intake of fruit and vegetables may lower cardiometabolic risk factors in this population

Duality between N=5 and N=6 Chern-Simons matter theory

We provide evidences for the duality between ${\cal N}=6$ $U(M)_{4} \times U(N)_{-4}$ Chern-Simons matter theory and ${\cal N}=5$ $O(\hat{M})_{2} \times USp(2\hat{N})_{-1}$ theory for a suitable $\hat{M},\hat{N}$ by working out the superconformal index, which shows perfect matching. For ${\cal N}=5$ theories, we show that supersymmetry is enhanced to ${\cal N}=6$ by explicitly constructing monopole operators filling in $SO(6)_R$ $R$-currents. Finally we work out the large $N$ index of $O(2N)_{2k} \times USp(2N)_{-k}$ and show that it exactly matches with the gravity index on $AdS_4 \times S^7/D_k$, which further provides additional evidence for the duality between the ${\cal N}=5$ and ${\cal N}=6$ theory for $k=1$Comment: 15 pages; references adde

Classical double-layer atoms: artificial molecules

The groundstate configuration and the eigenmodes of two parallel two-dimensional classical atoms are obtained as function of the inter-atomic distance (d). The classical particles are confined by identical harmonic wells and repel each other through a Coulomb potential. As function of d we find several structural transitions which are of first or second order. For first (second) order transitions the first (second) derivative of the energy with respect to d is discontinuous, the radial position of the particles changes discontinuously (continuously) and the frequency of the eigenmodes exhibit a jump (one mode becomes soft, i.e. its frequency becomes zero).Comment: 4 pages, RevTex, 5 ps figures, to appear in Phys.Rev.Let