Portfolio selection problems in practice: a comparison between linear and quadratic optimization models

Several portfolio selection models take into account practical limitations on the number of assets to include and on their weights in the portfolio. We present here a study of the Limited Asset Markowitz (LAM), of the Limited Asset Mean Absolute Deviation (LAMAD) and of the Limited Asset Conditional Value-at-Risk (LACVaR) models, where the assets are limited with the introduction of quantity and cardinality constraints. We propose a completely new approach for solving the LAM model, based on reformulation as a Standard Quadratic Program and on some recent theoretical results. With this approach we obtain optimal solutions both for some well-known financial data sets used by several other authors, and for some unsolved large size portfolio problems. We also test our method on five new data sets involving real-world capital market indices from major stock markets. Our computational experience shows that, rather unexpectedly, it is easier to solve the quadratic LAM model with our algorithm, than to solve the linear LACVaR and LAMAD models with CPLEX, one of the best commercial codes for mixed integer linear programming (MILP) problems. Finally, on the new data sets we have also compared, using out-of-sample analysis, the performance of the portfolios obtained by the Limited Asset models with the performance provided by the unconstrained models and with that of the official capital market indices

Surveys for Schistosomiasis and Soil Transmitted Helminths in Luangwa, Kalabo and Serenje Districts of Zambia

Background: Earlier publications have indicated that human infections with schistosomes and soil transmitted helminths (STH) are widespread in Zambia. Despite being classified as a moderate endemic country for these infections, and a recent modelling study suggesting an average schistosomiasis prevalence of 26% among school aged children, there is a lack of published data on the present occurrence and distribution of these infections.Design: Cross sectional surveys for schistosomiasis and STH were carried out among individuals aged 4-20 years at three sites in Luangwa, Kalabo and Serenje districts, as an added component to comprehensive studies on lymphatic filariasis. Urine samples were examined for hematuria and Schistosoma haematobium ova using the Nuclepore filtration technique. Stool samples were examined for S. mansoni and STH ova using the Kato- Katz technique.Results: The prevalence of S. haematobium was generally low, with the Serenje site recording the highest of 3.0%. S. mansoni was only seen at the Kalabo site, which had a moderate prevalence of 37.5%. Hookworm infections were relatively common at all three sites, with prevalences ranging from 12.1 to 35.0%. Other more rare STH infections noted were Ascaris lumbricoides, Hymenolepis nana and Enterobius vermicularis.Conclusions: The study confirmed that schistosomiasis and STH infections were endemic at the study sites, but also suggested that the prevalences had declined compared to earlier reports. There is need for more surveys to be carried out to assess the current distribution and prevalence of these infections to provide guidance for implementation of mass drug administration for their control.

Surveys for Mansonella perstans Filariasis in Kalabo, Kazungula, Choma and Kafue Districts of Zambia

Background: Past case reports have documented Mansonella perstans infections in Zambia. However, knowledge on the epidemiology and geographical distribution of this infection in the country is lacking.  This paper reports on surveys for M. perstans in communities in four districts (Kalabo, Kazungula, Choma and Kafue) in the Southern and Western parts of Zambia.Design: The study was cross sectional. In Kalabo District, volunteers from three villages aged one year and above were recruited and had thick blood smears prepared. In the other three districts individuals aged 15 years and above who reported to selected health centres from the surrounding communities were recruited and had thick blood smears prepared. The blood smears were stained with Giemsa and examined for M. perstans microfilariae (mf).Results: A total of 1439 individuals were recruited and examined (425, 348, 306 and 360 from Kalabo, Kazungula, Choma and Kafue, respectively). No M. perstans mf were seen in any of the blood smears.Conclusions: The failure to find M. perstans mf was surprising considering previous case reports, even from some of the surveyed areas. There is a need for more surveys to be carried in other parts of the country to ascertain the distribution of M. perstans. Health practitioners should moreover be informed  about this  infection, and trained to be able to accurately distinguish M. perstans infections from those of Wuchereria bancrofti, which are also endemic in Zambia

Surveys for Mansonella perstans Filariasis in Kalabo, Kazungula, Choma and Kafue Districts of Zambia

Background: Past case reports have documented Mansonella perstans infections in Zambia. However, knowledge on the epidemiology and geographical distribution of this infection in the country is lacking. This paper reports on surveys for M. perstans in communities in four districts(Kalabo, Kazungula, Choma and Kafue) in the Southern and Western parts of Zambia.Design: The study was cross sectional. In the Kalabo District surveys, individuals aged one year and above had thick blood smears prepared and examined for M. perstans microfilariae (mf). In the other three districts the study design was retrospective and prospective, i.e. previously examined archived malaria slides from health centres were re-examined for M. perstans mf and at the same time individuals aged 15years and above had thick blood spears prepared and examined for M. perstans mf.Results: The retrospective study could only be undertaken in Choma District due to change in malaria examination method in the other districts from conventional preparation of Giemsa stained thick blood smears to use of rapid diagnostic tests. For the prospective surveys, out of the 1439 individuals recruited and examined, no M. perstans mf were seen in any of the blood smears.Conclusions: The failure to find M. perstans mf was surprising considering previous case reports, even from some of surveyed areas. There is a need for more surveys to be carried in other parts of the country to ascertain the distribution of M. perstans. Health practitioners should moreover be informed about this infection, and trained to be able to accurately distinguish M. perstans infections from those of W. bancrofti, which are also endemic in Zambia

Consumption habits of pregnant women and implications for developmental biology: a survey of predominantly Hispanic women in California

BACKGROUND: Healthy post-pregnancy outcomes are contingent upon an informed regimen of prenatal care encouraging healthy maternal consumption habits. In this article, we describe aspects of maternal intake of food, drink, and medication in a population of predominantly Hispanic women in Southern California. Potential implications for unhealthy prenatal dietary choices are discussed. METHODS: The Food, Beverage, and Medication Intake Questionnaire (FBMIQ) measures common practices of maternal consumption during pregnancy. The FBMIQ was administered to English and Spanish speaking pregnant and recently pregnant (36 weeks pregnant - 8 weeks post-partum) women over the age of 18 who were receiving care from a private medical group in Downey CA. RESULTS: A total of 200 women completed the FBMIQ. Consumption habits of healthy foods and beverages, unhealthy foods, unhealthy beverages, and medication are characterized in this article. Data indicate widespread consumption of fresh fruit, meats, milk and juice and indicate most women used prenatal vitamin supplements. Studies in developmental neuroscience have shown that certain substances may cause teratogenic effects on the fetus when ingested by the mother during pregnancy. Those potentially harmful substances included in our study were Bisphenol-A (BPA), methylmercury, caffeine, alcohol and certain medications. Our results show that a proportion of the women surveyed in our study consumed BPA, methylmercury, caffeine, alcohol, and certain medications at varied levels during pregnancy. This represents an interesting finding and suggests a disconnect between scientific data and general recommendations provided to pregnant mothers by obstetricians. CONCLUSIONS: The results of our study demonstrate that a proportion of pregnant women consume substances that are potentially teratogenic and may impact the health and well being of the offspring. It is important to appraise healthy and unhealthy consumption habits in order to encourage healthy practices and alleviate future effects of preventable, toxin-induced developmental issues. Prenatal advising should discourage the consumption of dangerous foods, beverages, and medications that women commonly report eating during pregnancy

Measurement of W(+/-)Z production in proton-proton collisions at root s=7 TeV with the ATLAS detector

A study of W(+/-)Z production in proton-proton collisions at root s = 7 TeV is presented using data corresponding to an integrated luminosity of 4.6 fb(-1) collected with the ATLAS detector at the Large Hadron Collider in 2011. In total, 317 candidates, with a background expectation of 68 +/- 10 events, are observed in double-leptonic decay final states with electrons, muons and missing transverse momentum. The total cross-section is determined to be sigma(tot)(WZ) = 19.0(-1.3)(+1.4)(stat.) +/- 0.9(syst.) +/- 0.4(lumi.) pb, consistent with the Standard Model expectation of 17.6(-1.0)(+1.1) pb. Limits on anomalous triple gauge boson couplings are derived using the transverse momentum spectrum of Z bosons in the selected events. The cross-section is also presented as a function of Z boson transverse momentum and diboson invariant mass

Search for the associated production of the Higgs boson with a top quark pair in multilepton final states with the ATLAS detector

A search for the associated production of the Higgs boson with a top quark pair is performed in multilepton final states using 20.3 fb(-1) of proton-proton collision data recorded by the ATLAS experiment at root s = 8 TeVat the Large Hadron Collider. Five final states, targeting the decays H -> WW*, tau tau, and ZZ*, are examined for the presence of the Standard Model (SM) Higgs boson: two same-charge light leptons (e or mu) without a hadronically decaying tau lepton; three light leptons; two same-charge light leptons with a hadronically decaying tau lepton; four light leptons; and one light lepton and two hadronically decaying tau leptons. No significant excess of events is observed above the background expectation. The best fit for the t (t) over barH production cross section, assuming a Higgs boson mass of 125 GeV, is 2.1(-1.2)(+1.4) times the SM expectation, and the observed (expected) upper limit at the 95% confidence level is 4.7 (2.4) times the SM rate. The p-value for compatibility with the background-only hypothesis is 1.8s; the expectation in the presence of a Standard Model signal is 0.9 sigma. (C) 2015 CERN for the benefit of the ATLAS Collaboration. Published by Elsevier B.V