Stack and Queue Layouts via Layered Separators

It is known that every proper minor-closed class of graphs has bounded stack-number (a.k.a. book thickness and page number). While this includes notable graph families such as planar graphs and graphs of bounded genus, many other graph families are not closed under taking minors. For fixed $g$ and $k$, we show that every $n$-vertex graph that can be embedded on a surface of genus $g$ with at most $k$ crossings per edge has stack-number $\mathcal{O}(\log n)$; this includes $k$-planar graphs. The previously best known bound for the stack-number of these families was $\mathcal{O}(\sqrt{n})$, except in the case of $1$-planar graphs. Analogous results are proved for map graphs that can be embedded on a surface of fixed genus. None of these families is closed under taking minors. The main ingredient in the proof of these results is a construction proving that $n$-vertex graphs that admit constant layered separators have $\mathcal{O}(\log n)$ stack-number.Comment: Appears in the Proceedings of the 24th International Symposium on Graph Drawing and Network Visualization (GD 2016

Cyclic behaviour of deep reinforced concrete coupling beams

Six half-scale models of reinforced concrete coupling beams with span/depth ratios ≤ 2.0 were tested under reversed cyclic load by a newly developed test method that can accurately simulate the boundary conditions of coupling beams in coupled shear wall structures. Five of them were conventionally reinforced and one was diagonally reinforced. Span/depth ratio and reinforcement layout were the main structural variables studied. Test results revealed that the deep conventionally reinforced coupling beams behaved quite differently from the ordinary beams in frame structures. Generally, shear failure was more likely to occur. Moreover, the additional longitudinal reinforcement bars (those placed near the centroidal axis) could contribute significantly to bending strength and therefore lead to an increase in shear demand. Nevertheless, the measured drift ratios of the conventionally reinforced coupling beams still reached 3·6-5·7%, which are not small for deep coupling beams. On the other hand, it was found that the provision of diagonal reinforcement radically changed the load resisting mechanism and significantly improved the energy dissipation capacity of the coupling beam. However, it had not improved the deformability of the coupling beam.published_or_final_versio

Testing of coupling beams with equal end rotations maintained and local joint deformation allowed

The strength and ductility of the coupling beams in coupled shear walls can significantly affect the nonlinear behaviour and earthquake resistance of the whole building structure. However, although extensive testing of coupling beams has been performed, the boundary conditions-that the rotations at the two ends of a coupling beam are equal and that local deformation occurs at the beam-wall joints, which could have substantial influence on the test results-have not been correctly simulated. Herein, a new method of testing reinforced concrete coupling beams that ensures equal rotations at the ends of the beam specimen and takes into account local deformation at the beam-wall joints is developed. The method has been successfully applied to test typical reinforced concrete coupling beams with relatively small span/depth ratios and proven to be suitable for studying the post-peak behaviour and failure characteristics of short coupling beams. Test results obtained so far indicate that reinforced concrete coupling beams with small span/depth ratios behave quite differently from ordinary beams in frame structures and that the local deformation at beam-wall joints is quite substantial. Complete load-deflection curves have been acquired and the strength and ductility of the coupling beams evaluated.published_or_final_versio

Tapering promotes propriety for Fourier transforms of real-valued time series

We examine Fourier transforms of real-valued stationary time series from the point of view of the statistical propriety. Processes with a large dynamic range spectrum have transforms that are very significantly improper for some frequencies; the real and imaginary parts can be highly correlated, and the periodogram will not have the standard chi-square distribution at these frequencies, nor have two degrees of freedom. Use of a taper reduces impropriety to just frequencies close to zero and Nyquist only, and frequency ranges where the propriety breaks down can be quite accurately and easily predicted by half the autocorrelation width of |H * H(2f)|, denoted by c, where H(f) is the Fourier transform of the taper and * denotes convolution. For vector time series we derive an improved distributional approximation for minus twice the log of the generalized likelihood ratio test statistic for testing for propriety of the Fourier transform at any frequency, and compare frequency range cutoffs for propriety determined by the hypothesis test with those determined by c

Comparison between modern polar and temperate skeletal carbonate mineralogy and oxygen and carbon isotopes, Antarctic and Tasmanian shelves

Modern bryozoan skeletal mineralogy varies with seawater temperature: polar Antarctic bryozoans are mainly low-Mg calcite, whereas temperate Tasmanian bryozoans are predominantly high-Mg calcite with variable amounts of aragonite. Bivalve molluscs from both polar and temperate regions are mainly aragonite with variable amounts of low-Mg calcite. The o180 and o13C isotope fields of polar skeletons are clearly separated from the temperate fields, due to differences in seawater temperatures, levels of o13C in seawater and the circulation of seawater masses. 0180 values of bryozoa, benthic foraminifera and bivalve molluscs give near-equilibrium seawater temperatures. Small differences in 0180 and o13C values between skeletons are due to their variable growth rates. Meltwater effects are small (7%) in the polar Antarctic Sea and high (<25%) in the shallow Arctic Sea because ice sheets do not melt in the Antarctic region, whereas significant melting of ice sheets occurs in summer in the Arctic regions. Skeletal carbonate mineralogy and 0180 and o13C variations can be used in the recognition of ancient, non-tropical carbonate skeletons and carbonate rocks

Dynamic response of multiple coplanar interface cracks between two dissimilar piezoelectric materials

The linear piezoelectricity theory is applied to investigate the dynamic response of coplanar interface cracks between two dissimilar piezoelectric materials subjected to the mechanical and electrical impacts. The number of cracks is arbitrary, and the interface cracks are assumed to be permeable for electric field. Integral transforms and dislocation density function are employed to reduce the problem to Cauchy singular integral equations. Numerical examples are given to show the effects of crack relative position and material property parameters on the variations of dynamic energy release rate.postprin

Tuberculosis-HIV Co-infection Rate among Smear Positive Pulmonary Tuberculosis Patients and Associated Risk Factors in Southern Ethiopia

The objective of this study was to estimate HIV infection and associated risk factors among smear positive pulmonary TB patients in Southern Ethiopia. A cross-sectional study design was used to recruit 221 consecutive smear positive pulmonary TB patients visiting three hospitals in Gamo Goffa Zone from March, 2013 to February, 2014. A structured questionnaire was used to collect data on socio demographic, behavioral and economic factors from study units. Chi-square, fisher’s exact test and logistic regression were used to assess the association between the above factors and HIV infection among smear positive pulmonary TB. The rate of HIV-TB co-infection among sputum smear-positive pulmonary TB patients in southern Ethiopia was 6.8% with 95% confidence interval of 3.3 to 10.3%. Drinking alcohol was significantly associated with increased risk of HIV infection among smear positive pulmonary TB patients in univariable logistic regression but that association was not maintained after controlling for potential confounding variables. Other factors significantly associated with HIV infection among the study population were previous anti-TB treatment, being resident in urban area and participants who had monthly income of less than or equal to 1000 Ethiopian birr as compared to those who had no regular monthly income. The rate of TB-HIV infection among smear positive pulmonary TB patients in Southern Ethiopia was low. However, the government or other partner organizations should work on decreasing the burden of co-infection through designing strategy on preventing HIV transmission in the urban area; increase the monthly income of citizens while enhancing TB-HIV collaborative activity to prevent reactivation of TB.Keywords: TB-HIV co-infection Smear-positive pulmonary TB Risk factors South Ethiopi