2009, The Year Of Diversification

Today, no company is safe, no industry is secure, no rating is impartial, no advisor is certain, and no country is immune from economic and financial malaise. The days of optimistically believing the advisors and benefiting from investment in equity markets are long gone. Any recommended asset or a strategy is questioned and everywhere doubts outdo trust.  In these financial dark days, however, few things are still true: rational and logical approaches endure, sound and understandable assumptions hold, diversification works.Diversification is a simple and yet powerful commonsensical approach to investment. It is easy to do and it works well for small and large portfolios with few or many assets. If one chooses to use diversifications techniques, an important question to ask is whether it is based on data across all time-periods, or over primarily down markets when diversification is most valuable. This study examines the performance of a well-diversified portfolio and compares the results with the performance of other portfolios including an equally-weighted equity portfolio over the down market from April 2, 2007 to April 4, 2009.Although there still exits a sense of uneasiness in the stock market about equity investing, the above average rate of returns and steady growth of diversified portfolios over the past two troubling years compels investors to consider diversifications again. The main goal of this work is to first examine the performance of several companies and compare their risk-adjusted returns to the returns of indexes, mainly S&P 500, and then compare the performance of a well-diversified portfolio with a balanced equity portfolio. Specifically, this study is going to address whether the performance of a well-diversified portfolio meets or surpasses the performance of a diversified equally weighted portfolio. More importantly the emphasis of this work is to determine whether diversification consistently and significantly contributes positively to the performance of the US equity portfolios.  The asset selection and the optimization process applied to portfolios are identical to maintain consistency and comparability of the results. For each portfolio we used the 2005-2007 daily observations to optimize allocations and we used the 2007-2009 data to evaluate the performance of each portfolio

On Power Allocation for Distributed Detection with Correlated Observations and Linear Fusion

We consider a binary hypothesis testing problem in an inhomogeneous wireless sensor network, where a fusion center (FC) makes a global decision on the underlying hypothesis. We assume sensors observations are correlated Gaussian and sensors are unaware of this correlation when making decisions. Sensors send their modulated decisions over fading channels, subject to individual and/or total transmit power constraints. For parallel-access channel (PAC) and multiple-access channel (MAC) models, we derive modified deflection coefficient (MDC) of the test statistic at the FC with coherent reception.We propose a transmit power allocation scheme, which maximizes MDC of the test statistic, under three different sets of transmit power constraints: total power constraint, individual and total power constraints, individual power constraints only. When analytical solutions to our constrained optimization problems are elusive, we discuss how these problems can be converted to convex ones. We study how correlation among sensors observations, reliability of local decisions, communication channel model and channel qualities and transmit power constraints affect the reliability of the global decision and power allocation of inhomogeneous sensors

Important statistical points to improve and promote the methodology of the articles on medical: a systematic review article for authors and reviewers

زمینه و هدف: کیفیت متدولوژی مقالات از جمله فاکتورهای مهمی است که مورد توجه پژوهشگران قرار می گیرد. این مقاله با هدف تعیین رهنمودهای آماری در زمینه ارتقاء کیفیت متدولوژی مقالات مرتبط با علوم پزشکی به منظور کمک به نویسندگان و داوران مقالات تدوین شد. روش بررسی: این مطالعه یک بررسی از نوع مرور نظام مند است. ابتدا در پایگاه اطلاعاتی Pub Med، کلمات کلیدی "Epidemiologic Methods/analysis"Mesh "Epidemiologic Methods/epidemiology" و Statistical Reporting انتخاب گردید. سپس متون مرتبط از پایگاه های اطلاعاتی معتبر جستجو شد. مرتبط بودن مقالات، داشتن دیدگاه و ارائه رهنمود آماری در مقاله و همچنین موافقت حداقل دو نفر از سه نفر تیم بررسی کننده مقالات از شرایط ورود مقالات به مطالعه بود. یافته ها: دویست مقاله مرتبط یافت گردید. 32 مقاله شرایط ورود به مطالعه را داشتند. بر اساس مقالات بررسی شده،30 نکته کاربردی در بهبود و ارتقاء کیفیت متدولوژی مقالات نقش تعیین کننده دارند. از جمله نکته های مهم می توان به معرفی و توصیف جامعه هدف و جمعیت آماری و ذکر نام مطالعه، معرفی متغیرهای مستقل، وابسته و متغیرهای مخدوش کننده، گزارش حجم نمونه برای زیر گروه ها و کل مطالعه، خلاصه سازی داده ها متناسب با توزیع آماری آن ها، ذکر نام آزمون های آماری مورد استفاده، گزارش نوع میزان (میزان بروز، میزان های بقا)، نسبت (نسبت شانس، نسبت خطر) یا خطر (خطر مطلق، خطر نسبی، اختلاف خطر) با حدود اطمینان 95%، تحلیل مشاهده های انسانی بر حسب جنسیت و نرم افزار مورد استفاده اشاره نمود. نتیجه گیری: مهمترین فاکتورهایی که در کیفیت متدولوژی مقالات، نقش تعیین کننده دارند، در این مطالعه گزارش گردید. به کارگیری این فاکتورها توسط نویسندگان و داوران مقالات می تواند منجر به بهبود کیفیت مجلات گردد. همچنین کاربست نکته ها و رهنمون های این مطالعه در روش کار طرح ها، می تواند از خطاهای پژوهش اجتناب نماید

Important statistical points to improve and promote the methodology of the articles on medical sciences, particularly nephrology and kidney; a review article.

BACKGROUND Quality of articles' methodology is one of the important factors which is considered by researchers. OBJECTIVES This study was conducted to determine statistical guidelines on promotion of methodology's quality in the articles concerning medical sciences, particularly nephrology, to assist authors and reviewers. MATERIALS AND METHODS This study is a systematic review. Initially, the keywords "Epidemiologic Methods/analysis" [Mesh] OR "Epidemiologic Methods/epidemiology" and "reporting" were selected in Medline database. Then, reliable databases were searched for relevant publications. Being relevant, containing viewpoints, and recommending statistical guidelines as well as approval of at least two of the three examiners of articles were determined as the inclusion criteria into the study. RESULTS Two hundred relevant articles were retrieved. Thirty-two articles met the inclusion criteria. By the examined articles, 30 applied points have determinative role for improving and promoting quality of articles methodology. Of the important points, introducing and describing target community and statistical population, mentioning article title, introducing independent and dependent variables as well as confounders, reporting sample size for subgroups and the whole study, summarizing the data according to their statistical distribution (reporting mean and standard deviation for data with normal distribution), reporting the type of rate (incidence, survival), ratio (odds, hazard) or risk (absolute, relative, difference) with 95% CI and the used software could be mentioned. CONCLUSION The most important factors contributing greatly to the quality of articles' methodology on nephrology were reported in the present study. Applying these factors by articles authors and reviewers could lead to improve articles' and journals' quality. In addition, use of the findings of the present study in articles' materials and methods could avoid research errors

Two Staged Portfolio Optimizations

The primary goal of this work is to determine if an active portfolio optimization strategy utilizing a two staged optimization approach outperforms an ordinary optimization technique.   Both portfolio optimization models are based on Markowitz’s Modern Portfolio Theory (MPT), which relies on assets’ mean, variance, and correlation to maximize returns at any given level of risk. For the two staged optimization approach the process of optimization is applied twice.  In the first stage, it is used to select an optimal portfolio of industries, and in the second stage optimization is applied to determine an optimal portfolio consisting of stocks within each industry. Our research indicates that portfolios formed based on ordinary optimization outperforms two staged portfolios and Market indexes by 37% during a bear market (2002) and outperforms Dow Jones Industrial Average and  S&P 500 by more than 13% during a bull market (2003). The performance of each model was determined by the capital gains and the dividend returns during the 2002 to 2003 time period

Reconfigurable Antennas in mmWave MIMO Systems

The key obstacle to achieving the full potential of the millimeter wave (mmWave) band has been the poor propagation characteristics of wireless signals in this band. One approach to overcome this issue is to use antennas that can support higher gains while providing beam adaptability and diversity, i.e., reconfigurable antennas. In this article, we present a new architecture for mmWave multiple-input multiple-output (MIMO) communications that uses a new class of reconfigurable antennas. More specifically, the proposed lens-based antennas can support multiple radiation patterns while using a single radio frequency chain. Moreover, by using a beam selection network, each antenna beam can be steered in the desired direction. Further, using the proposed reconfigurable antenna in a MIMO architecture, we propose a new signal processing algorithm that uses the additional degrees of freedom provided by the antennas to overcome propagation issues at mmWave frequencies. Our simulation results show that the proposed reconfigurable antenna MIMO architecture significantly enhances the performance of mmWave communication systems

The Empirical Evidence Conclusively Supports Global Investing

Although there still exits a sense of uneasiness in the stock market about global investing, the above average rate of returns and steady growth of international companies for the past ten years compels prudent investor to invest abroad. The main goal of this work is to examine the performance of foreign companies and compare their risk-adjusted returns to the returns of the US companies. In this process we selected the foreign companies that have been accepted by our financial market and traded in the US as ADR (American Depository Receipts) in NYSE or NASDAQ. Additionally, we have considered only those ADRs that had high volume and outperformed the industry index. Specifically, this study is going to address whether the performance of a global portfolio meets or surpasses the performance of a diversified domestic portfolio. More importantly the emphasis of this work is to determine whether the global portfolios consistently and significantly outperformed the US equity portfolios. The asset selection and the optimization process applied to domestic and international portfolios are identical to maintain consistency and comparability of the results. For each portfolio we used the 2003-2004 daily observations to optimize allocations and we used the 2005-2006 data to evaluate the performance of each portfolio

Prevalence of major coronary heart disease risk factors in Iran

Background and aims: Coronary heart diseases (CHDs) contribute to mortality, morbidity, disability, productivity and quality of life. This study was aimed to determine the prevalence of major risk factors for CHD in the provinces of Iran. Methods:This study reported pre-existing data and was of secondary, descriptive type. Prevalence of non-communicable disease (NCD) risk factors was defined for the provinces of Iran. A reliable report of NCD risk factors, the national surveillance program conducted in Iran, such as type II diabetes, hypertension and mean body mass index (BMI), smoking, hookah smoking, high cholesterol and obesity was used. Results: The highest and lowest prevalence of hypertension was obtained in Bushehr (20.85) and Yazd (12.86) provinces, respectively. The highest mean BMI was reported from Mazandaran province (26) and the lowest from Sistan and Baluchestan province (22.50). Qom province had the highest prevalence of diabetes (27.65). The highest prevalence of high cholesterol was obtained in Lorestan province (50.87 ) and the lowest in the Khouzestan province (22.71). East Azarbaijan province had the highest prevalence of smoking (14.8) and Kurdistan province the lowest (0.16). Hookah smoking was most prevalent in Hormozgan province (7.62). The highest prevalence of physical activities was reported from Sistan and Baluchestan province (47.84) and the lowest from Kohgiluyeh and Boyer-Ahmad (22.2). Conclusion:Prevalence of CHD risk factors is the main priority for the Iranian health system. There is a need for intervention programs in the provinces which are at greater risk as well as for modification of people’s lifestyle