Communication Over MIMO Broadcast Channels Using Lattice-Basis Reduction

A simple scheme for communication over MIMO broadcast channels is introduced which adopts the lattice reduction technique to improve the naive channel inversion method. Lattice basis reduction helps us to reduce the average transmitted energy by modifying the region which includes the constellation points. Simulation results show that the proposed scheme performs well, and as compared to the more complex methods (such as the perturbation method) has a negligible loss. Moreover, the proposed method is extended to the case of different rates for different users. The asymptotic behavior of the symbol error rate of the proposed method and the perturbation technique, and also the outage probability for the case of fixed-rate users is analyzed. It is shown that the proposed method, based on LLL lattice reduction, achieves the optimum asymptotic slope of symbol-error-rate (called the precoding diversity). Also, the outage probability for the case of fixed sum-rate is analyzed.Comment: Submitted to IEEE Trans. on Info. Theory (Jan. 15, 2006), Revised (Jun. 12, 2007

Macroscopic Resonant Tunneling in the Presence of Low Frequency Noise

We develop a theory of macroscopic resonant tunneling of flux in a double-well potential in the presence of realistic flux noise with significant low-frequency component. The rate of incoherent flux tunneling between the wells exhibits resonant peaks, the shape and position of which reflect qualitative features of the noise, and can thus serve as a diagnostic tool for studying the low-frequency flux noise in SQUID qubits. We show, in particular, that the noise-induced renormalization of the first resonant peak provides direct information on the temperature of the noise source and the strength of its quantum component.Comment: 4 pages, 1 figur

Prevalence of exclusive breastfeeding and its determinants in first 6 months of life: A prospective study

Background: Exclusive breastfeeding for first 6 months of life is recommended under Infant and Young Child Feeding practices in India. The objective of present study was to estimate the prevalence of exclusive breastfeeding during first 6 months of life of babies and to identify factors that interfere with the practice in the study area. Methods: A prospective cohort of 462 women who delivered at maternity unit of Government Medical College & Hospital, Rajkot, which is a tertiary care centre for the district, was studied. Data collection was done at hospital as well as during home visits of babies at 1, 3 and 6 months. Factors related to cessation of breastfeeding were analyzed using univariate, bivariate and multivariate analysis. Results: All 462 mothers reported breastfeeding their newborns. Prevalence of exclusive breastfeeding reported at 3 months was 97% which declined to 62% by 6 months of age of infants. Bivariate analysis revealed no significant association between interruption of exclusive breastfeeding before 6 months of age and various demographic, socioeconomic, maternal and infant characteristics. Multivariate analysis by logistic regression demonstrated no association between discontinuation of exclusive breastfeeding and socioeconomic status, maternal education and maternal age, number of antenatal visits, maternal employment and initiation of breastfeeding after delivery. Conclusion: Exclusive breastfeeding prevalence rate found higher than at national level indicating better feeding practices in these part of India. Also, factors classically considered as supportive for breastfeeding had shown no association with breastfeeding pattern in present study

Mesoscale modelling of polymer aggregate digestion

We use mesoscale simulations to gain insight into the digestion of biopolymers by studying the break-up dynamics of polymer aggregates (boluses) bound by physical cross-links. We investigate aggregate evolution, establishing that the linking bead fraction and the interaction energy are the main parameters controlling stability with respect to diffusion. We show $\textit{via}$ a simplified model that chemical breakdown of the constituent molecules causes aggregates that would otherwise be stable to disperse. We further investigate breakdown of biopolymer aggregates in the presence of fluid flow. Shear flow in the absence of chemical breakdown induces three different regimes depending on the flow Weissenberg number ($Wi$). i) At $Wi \ll 1$, shear flow has a negligible effect on the aggregates. ii) At $Wi \sim 1$, the aggregates behave approximately as solid bodies and move and rotate with the flow. iii) At $Wi \gg 1$, the energy input due to shear overcomes the attractive cross-linking interactions and the boluses are broken up. Finally, we study bolus evolution under the combined action of shear flow and chemical breakdown, demonstrating a synergistic effect between the two at high reaction rates

ISIS Menuju Asia Tenggara: Ancaman dan Kerja Sama Keamanan Kawasan dalam Menghadapi Peningkatan Ekspansi ISIS

The Marawi war in early 2017 became the most explicit evidence of ISIS terrorist group existence in Southeast Asia. The region is predicted to be their new territory for expansion under the leadership of Abu Bakar Al-Baghdadi, even more after their lost at many territories in the Middle East. The Southeast Asia countries immediately generate preventive actions by strengthening the territorial security cooperation. This paper examines how Southeast Asia has great possibility to be the new destination for ISIS to invade and how the countries in Southeast Asia deal the threat. It is assumed that ISIS as part of global terrorism is trying to widen their expansion to Southeast Asia and how the countries in Southeast Asia rise up cooperation among them to prevent and resist from the ISIS expansion. Pertempuran di Marawi pada awal tahun 2017 menjadi bukti paling jelas hadirnya ancaman kelompok teroris ISIS di kawasan Asia Tenggara. Asia Tenggara diprediksi menjadi tujuan baru bagi agenda perluasan wilayah kekhalifahan Negara Islam di bawah Abu Bakar Al-Baghdadi setelah mengalami banyak kekalahan dan kehilangan wilayah kekuasaan di Timur Tengah. Negara-negara di Asia Tenggara segera mengambil langkah atraktif dengan meningkatkan kerja sama keamanan kawasan sebagai upaya sekuritisasi. Tulisan ini mengkaji bagaimana kawasan Asia Tenggara berpotensi besar menjadi tujuan baru bagi ISIS untuk kembali membangun kekuatan dan bagaimana upaya negara-negara di Asia Tenggara menghadapi ancaman tersebut. Tulisan ini berpendapat bahwa ISIS sebagai bagian dari terorisme global sedang berusaha memperluas pengaruhnya ke Asia Tenggara dan peningkatan kerja sama keamanan kawasan yang dilakukan negara-negara di Asia Tenggara, dapat dipahami sebagai bentuk upaya menghadapi ekspansi ISIS di kawasan

Application of Large Prestress Strands in Precast/Prestressed Concrete Bridges

The objective of this research is to investigate the advantage of using large-diameter 0.7-inch (18 mm) strands in pretention applications. Large-diameter strands are advantageous in bridge construction due to the increased girders capacity required to sustain exponential increase in vehicle numbers, sizes, and weights. In this research, flexure capacity of girders fabricated using 0.7-inch (18 mm) diameter strands will be calculated and compared to bridge capacities constructed using smaller strands. Finally, two similar bridge sections will be designed using 0.6-inch (15 mm) and 0.7-inch (18 mm) diameter strands to quantify the structural advantages of increased strand diameter. The research findings showed that a smaller number of girders is required for bridge construction when larger strands are used. Four girders are required to design the bridge panel using high performance concrete and large diameter strands, as compared to 6 girders required when regular concrete mix designs and normal size strands are used. The advantages of large strands and high-performance concrete mixes include expedited construction, reduced project dead loads, and reduced demand for labor and equipment. Thus, large strands can partially contribute to the improvement of bridge conditions, minimize construction cost, and increase construction site safety

ON THE DYNAMICS OF COMMERCIAL FISHING AND PARAMETER IDENTIFICATION

This paper has two main objectives. The first is to develop a dynamic model of commercial fisheries different from most existing models that assume optimizing behavior. The industry is assumed to have a well-defined index of performance. Based upon this index, the decision to invest or not is made. We do not, however, assume that the industry or firm is efficient or optimal in its operations. The second is that a new approach of fitting model dynamics to time series data is employed to simultaneously estimate the poorly known initial conditions and parameters of nonlinear fisheries dynamics. The approach is a data assimilation technique known as the variational adjoint method. Estimation of the poorly known initial conditions is one of the attractive features of the variational adjoint method.Resource /Energy Economics and Policy,