Estimation of sexual behavior in the 18-to-24-years-old Iranian youth based on a crosswise model study

Background: In many countries, negative social attitude towards sensitive issues such as sexual behavior has resulted in false and invalid data concerning this issue.This is an analytical cross-sectional study, in which a total number of 1500 single students from universities of Shahroud City were sampled using a multi stage technique. The students were assured that their information disclosed for the researcher will be treated as private and confidential. The results were analyzed using crosswise model, Crosswise Regression, T-test and Chi-square tests. Findings. It seems that the prevalence of sexual behavior among Iranian youth is 41% (CI = 36-53). Conclusion: Findings showed that estimation sexual relationship in Iranian single youth is high. Thus, devising training models according to the Islamic-Iranian culture is necessary in order to prevent risky sexual behavior. © 2014 Vakilian et al.; licensee BioMed Central Ltd

High Rate/Low Complexity Space-Time Block Codes for 2x2 Reconfigurable MIMO Systems

In this paper, we propose a full-rate full-diversity space-time block code (STBC) for 2x2 reconfigurable multiple-input multiple-output (MIMO) systems that require a low complexity maximum likelihood (ML) detector. We consider a transmitter equipped with a linear antenna array where each antenna element can be independently configured to create a directive radiation pattern toward a selected direction. This property of transmit antennas allow us to increase the data rate of the system, while reducing the computational complexity of the receiver. The proposed STBC achieves a coding rate of two in a 2x2 MIMO system and can be decoded via an ML detector with a complexity of order M, where M is the cardinality of the transmitted symbol constellation. Our simulations demonstrate the efficiency of the proposed code compared to existing STBCs in the literature.Comment: arXiv admin note: text overlap with arXiv:1505.0646

High-Rate Space Coding for Reconfigurable 2x2 Millimeter-Wave MIMO Systems

Millimeter-wave links are of a line-of-sight nature. Hence, multiple-input multiple-output (MIMO) systems operating in the millimeter-wave band may not achieve full spatial diversity or multiplexing. In this paper, we utilize reconfigurable antennas and the high antenna directivity in the millimeter-wave band to propose a rate-two space coding design for 2x2 MIMO systems. The proposed scheme can be decoded with a low complexity maximum-likelihood detector at the receiver and yet it can enhance the bit-error-rate performance of millimeter-wave systems compared to traditional spatial multiplexing schemes, such as the Vertical Bell Laboratories Layered Space-Time Architecture (VBLAST). Using numerical simulations, we demonstrate the efficiency of the proposed code and show its superiority compared to existing rate-two space-time block codes

The impact of the Iranian constitution on the law making power of the parliament (Majlis)

In this research the law making power of the Iranian parliament is studied at two levels: Firstly, the power of the parliament according to the Constitution is explored. Secondly its power in real politics is analysed. It is shown that the law making power of the parliament as an elected institution can be limited by the unelected institutions which are enshrined in the Constitution. Also the political composition of the elected institutions (parliament and executive) whether they are Conservative-dominated or Reformist-dominated, can define the actual law making power of the parliament. It is concluded that the law making power of the parliament oscillates on a spectrum: at one end there is a weak law making legislature and at the other end one can see a policy influencing legislature. The main content of the chapters is as follows: The first chapter is dedicated to introduction where the research questions and thesis methodology is explained. In the second chapter the most important literature, especially that which considers the external and internal variables and typology of legislatures, is reviewed. In the third chapter the historical evolution of the Iranian Parliament in the Qajar, First and Second Pahlavi Eras is briefly discussed. The fourth chapter is dedicated to the Iranian parliament in the Islamic Republic Era. The key concepts which can explain the logic of the distribution of power within the Iranian Constitution, the relationship of the parliament to the executive power (elected institution) and other power centres ( unelected institutions), and the type of the political regime on the basis of the amended Constitution of 1989, is explained. Theoretical propositions are tested in chapter five. The Sixth and Seventh terms of the parliament, where the political composition changed fundamentally from one to the other, are chosen for case study and their law making power during the budget process analysed. The dichotomy of elected and unelected institutions is applied to the case in this chapter. Then the contribution of the elected and unelected institutions during the budget process is explained. The next part of this chapter considers the Sixth Majlis and its political context in general. The Majlis and executive interactions and the interaction of these two elected institutions with the Guardian Council and Expediency Council especially during the budget process, are analysed. The same approach is deployed for the Seventh Majlis which in terms of political composition was in stark contrast to the Sixth Majlis. It is shown how the political composition of the elected and unelected institutions can increase or decrease considerably the law making power of the Islamic Consultative Assembly. The overall conclusion of the thesis is provided in chapter six

Towards Tight Bounds for the Streaming Set Cover Problem

We consider the classic Set Cover problem in the data stream model. For $n$ elements and $m$ sets ($m\geq n$) we give a $O(1/\delta)$-pass algorithm with a strongly sub-linear $\tilde{O}(mn^{\delta})$ space and logarithmic approximation factor. This yields a significant improvement over the earlier algorithm of Demaine et al. [DIMV14] that uses exponentially larger number of passes. We complement this result by showing that the tradeoff between the number of passes and space exhibited by our algorithm is tight, at least when the approximation factor is equal to $1$. Specifically, we show that any algorithm that computes set cover exactly using $({1 \over 2\delta}-1)$ passes must use $\tilde{\Omega}(mn^{\delta})$ space in the regime of $m=O(n)$. Furthermore, we consider the problem in the geometric setting where the elements are points in $\mathbb{R}^2$ and sets are either discs, axis-parallel rectangles, or fat triangles in the plane, and show that our algorithm (with a slight modification) uses the optimal $\tilde{O}(n)$ space to find a logarithmic approximation in $O(1/\delta)$ passes. Finally, we show that any randomized one-pass algorithm that distinguishes between covers of size 2 and 3 must use a linear (i.e., $\Omega(mn)$) amount of space. This is the first result showing that a randomized, approximate algorithm cannot achieve a space bound that is sublinear in the input size. This indicates that using multiple passes might be necessary in order to achieve sub-linear space bounds for this problem while guaranteeing small approximation factors.Comment: A preliminary version of this paper is to appear in PODS 201

Simulation Studies on Estimation of Variance Components for Multilevel Models

With the presence of unequal sampling in a multilevel model, the weight inflated estimators for variance components can be biased even though the use of survey weights results in design consistent estimators of the parameters. In this thesis I will carry out a simulation study to examine the performance of current existing methods and I will examine the resampling method for correcting bias of estimators of variance components of a multilevel model with covariates. This study will be based on these three papers: “Weighting for Unequal Selection Probabilities in Multilevel Models” by D. Pfeffermann , C. J. Skinner, D.J. Holmes, H. Goldstein, and J. Rasbash (1998), Journal of the Royal Statistical Society Series B (Statistical Methodology), Vol. 60, No. 1, 23-40; “Design Consistent Estimators for a Mixed Linear Model on Survey Data” by Rong Huang and Mike Hidiroglou (2003), Business Survey Methods Division, Statistics Canada, Ottawa, Ontario K1Y 0A6; and “A resampling approach to estimate variance components of multilevel models” by Zilin Wang and Mary Thompson (2008), working paper

Factores de modelado que afectan la elección del teletrabajo y su impacto en la demanda en las redes de transporte

This research estimates the extent of using teleworking to mean the feasibility and appropriateness of this method of work for employees and professors according to their characteristics and features of career. The study population included university staff and professors in Tehran and data collection was carried out through 447 questionnaires. A logistic regression model was used to investigate the transport demand caused by teleworking. The results showed that various factors including history and percentage of telework and after that, the time delay of home-to-work and trave distance affected the model of transportation demand of professor’s members. For the staffing community, it had the greatest impact on teleworking, history and percentage of telework, followed by travel distances, latency from work to home, and latency from home to work