Assessment of the Multipath Mitigation Effect of Vector Tracking in an Urban Environment

Today, smart mobiles play an important role in our daily life. Most of these devices are equipped with a navigation function based on GNSS positioning. However, these devices may not work accurately in urban environments due to severe multipath interference and non-line of sight (NLOS) reception caused by nearby buildings. A promising approach for reducing the effect of multipath interference and NLOS reception is vector tracking (VT). VT is well-known for its robustness against poor signal-to-noise levels. However, its capability against multipath and NLOS has yet to be determined. The new combination of this paper is therefore to evaluate the performance of vector tracking in the presence of multipath and NLOS effects. A vector delay lock loop (VDLL) is used as the vector tracking technique. The noise tuning of the extended Kalman filter (EKF) in vector tracking is a key factor affecting its performance. Therefore, developed an adaptive noise tuning algorithm had been based on the measurement innovation. In order to evaluate vector tracking’s performance, equivalent conventional tracking loops are used as a control. GNSS signals were collected, while walking around in a challenging urban environment subject to multipath interference. The experimental results show that VT generates a more stable code numerical-controlled oscillator (NCO) frequency than CT does. This characteristic could reduce the impact of multipath interference which is reflected in a smaller position error using VT during most of run. To further test capability of VT against signal attenuation, this paper applies a signal cancellation method called direct signal cancellation algorithm to simulate the scenario of signal termination and NLOS reception. According to the simulation, VT provides not only robustness against signal termination but can also detect NLOS reception without any external aiding

Concordance of sibling's recall of measures of childhood socioeconomic position

<p>Abstract</p> <p>Background</p> <p>Studies of socioeconomic determinants of health often rely on recalled information on childhood socioeconomic position, despite limited evidence of the validity of this information. This study examined concordance between siblings of recalled measures of childhood socioeconomic position.</p> <p>Methods</p> <p>This cross-sectional study examined reports by 1280 adult sibling pairs in the National Survey of Midlife Development in the United States of seven measures of childhood socioeconomic position: father's occupation (in 9 categories), father having a professional occupation, father being a supervisor at work, father's education level, mother's education level, receipt of welfare payments, and subjective appraisal of being better or worse off financially than others.</p> <p>Results</p> <p>Concordance was high for father's professional occupation (0.97; 95% confidence interval (CI) 0.96, 0.98), father's occupation in 9 categories (0.76; 95% CI 0.73, 0.80), and receipt of welfare payments (0.95; 95% CI 0.93, 0.97). Concordance was lower for father's and mother's education level, and lowest for subjective appraisal of socioeconomic position (0.60; 95% CI 0.57, 0.64). Concordance of parental education was lower for sibling pairs with high school educations or less.</p> <p>Conclusion</p> <p>Concordance of recalled measures of childhood socioeconomic position by siblings is generally but not uniformly high.</p

Comparison of participants and non-participants to the ORISCAV-LUX population-based study on cardiovascular risk factors in Luxembourg

BACKGROUND: Poor response is a major concern in public health surveys. In a population-based ORISCAV-LUX study carried out in Grand-Duchy of Luxembourg to assess the cardiovascular risk factors, the non-response rate was not negligible. The aims of the present work were: 1) to investigate the representativeness of study sample to the general population, and 2) to compare the known demographic and cardiovascular health-related profiles of participants and non-participants. METHODS: For sample representativeness, the participants were compared to the source population according to stratification criteria (age, sex and district of residence). Based on complementary information from the "medical administrative database", further analysis was carried out to assess whether the health status affected the response rate. Several demographic and morbidity indicators were used in the univariate comparison between participants and non-participants. RESULTS: Among the 4452 potentially eligible subjects contacted for the study, there were finally 1432 (32.2%) participants. Compared to the source population, no differences were found for gender and district distribution. By contrast, the youngest age group was under-represented while adults and elderly were over-represented in the sample, for both genders. Globally, the investigated clinical profile of the non-participants was similar to that of participants. Hospital admission and cardiovascular health-related medical measures were comparable in both groups even after controlling for age. The participation rate was lower in Portuguese residents as compared to Luxembourgish (OR = 0.58, 95% CI: 0.48-0.69). It was also significantly associated with the professional status (P < 0.0001). Subjects from the working class were less receptive to the study than those from other professional categories. CONCLUSION: The 32.2% participation rate obtained in the ORISCAV-LUX survey represents the realistic achievable rate for this type of multiple-stage, nationwide, population-based surveys. It corresponds to the expected rate upon which the sample size was calculated. Given the absence of discriminating health profiles between participants and non-participants, it can be concluded that the response rate does not invalidate the results and allows generalizing the findings for the population

Consistency and precision of cancer reporting in a multiwave national panel survey

Abstract Background Many epidemiological studies rely on self-reported information, the accuracy of which is critical for unbiased estimates of population health. Previously, accuracy has been analyzed by comparing self-reports to other sources, such as cancer registries. Cancer is believed to be a well-reported condition. This paper uses novel panel data to test the consistency of cancer reports for respondents with repeated self-reports. Methods Data come from 978 adults who reported having been diagnosed with cancer in at least one of four waves of the Panel Study of Income Dynamics, 1999-2005. Consistency of cancer occurrence reports and precision of timing of onset were studied as a function of individual and cancer-related characteristics using logistic and ordered logistic models. Results Almost 30% of respondents gave inconsistent cancer reports, meaning they said they never had cancer after having said they did have cancer in a previous interview; 50% reported the year of diagnosis with a discrepancy of two or more years. More recent cancers were reported with a higher consistency and timing precision; cervical cancer was reported more inaccurately than other cancer types. Demographic and socio-economic factors were only weak predictors of reporting quality. Conclusions Results suggest that retrospective reports of cancer contain significant measurement error. The errors, however, are fairly random across different social groups, meaning that the results based on the data are not systematically biased by socio-economic factors. Even for health events as salient as cancer, researchers should exercise caution about the presumed accuracy of self-reports, especially if the timing of diagnosis is an important covariate.http://deepblue.lib.umich.edu/bitstream/2027.42/112656/1/12963_2010_Article_108.pd

Informed consent for HIV cure research in South Africa: issues to consider

Background: South Africa has made great progress in the development of HIV/AIDS testing, treatment and prevention campaigns. Yet, it is clear that prevention and treatment campaigns alone are not enough to bring this epidemic under control. Discussion: News that the “Berlin patient” and the “Mississippi baby” have both been “cured” of HIV brought hope to people living with HIV/AIDS in South Africa that a cure for HIV/AIDS is within reach. Despite the recent setbacks announced in the “Mississippi Baby” case, protocols aimed at curing HIV/AIDS are being developed in South Africa. However with evidence to suggest that participants in clinical trials do not understand the basic concepts in the informed consent process, there is concern that future participants in HIV/AIDS cure research will lack comprehension of the basic elements of future clinical trials that aims to cure HIV/AIDS and confuse research with clinical care. Summary: Research ethics committees have an important role to play in ensuring that participants understand the basic concepts discussed in the informed consent process, that they understand that research is not clinical care and they are unlikely to benefit from any early phase trials seeking to cure HIV/AIDS

Volunteer Bias in Recruitment, Retention, and Blood Sample Donation in a Randomised Controlled Trial Involving Mothers and Their Children at Six Months and Two Years: A Longitudinal Analysis

BACKGROUND: The vulnerability of clinical trials to volunteer bias is under-reported. Volunteer bias is systematic error due to differences between those who choose to participate in studies and those who do not. METHODS AND RESULTS: This paper extends the applications of the concept of volunteer bias by using data from a trial of probiotic supplementation for childhood atopy in healthy dyads to explore 1) differences between a) trial participants and aggregated data from publicly available databases b) participants and non-participants as the trial progressed 2) impact on trial findings of weighting data according to deprivation (Townsend) fifths in the sample and target populations. 1) a) Recruits (n = 454) were less deprived than the target population, matched for area of residence and delivery dates (n = 6,893) (mean [SD] deprivation scores 0.09[4.21] and 0.79[4.08], t = 3.44, df = 511, p<0.001). b) i) As the trial progressed, representation of the most deprived decreased. These participants and smokers were less likely to be retained at 6 months (n = 430[95%]) (OR 0.29,0.13-0.67 and 0.20,0.09-0.46), and 2 years (n = 380[84%]) (aOR 0.68,0.50-0.93 and 0.55,0.28-1.09), and consent to infant blood sample donation (n = 220[48%]) (aOR 0.72,0.57-0.92 and 0.43,0.22-0.83). ii) Mothers interested in probiotics or research or reporting infants' adverse events or rashes were more likely to attend research clinics and consent to skin-prick testing. Mothers participating to help children were more likely to consent to infant blood sample donation. 2) In one trial outcome, atopic eczema, the intervention had a positive effect only in the over-represented, least deprived group. Here, data weighting attenuated risk reduction from 6.9%(0.9-13.1%) to 4.6%(-1.4-+10.5%), and OR from 0.40(0.18-0.91) to 0.56(0.26-1.21). Other findings were unchanged. CONCLUSIONS: Potential for volunteer bias intensified during the trial, due to non-participation of the most deprived and smokers. However, these were not the only predictors of non-participation. Data weighting quantified volunteer bias and modified one important trial outcome. TRIAL REGISTRATION: This randomised, double blind, parallel group, placebo controlled trial is registered with the International Standard Randomised Controlled Trials Register, Number (ISRCTN) 26287422. Registered title: Probiotics in the prevention of atopy in infants and children

Highly polymorphic microsatellite markers for the assessment of male reproductive skew and genetic variation in Critically Endangered crested macaques (Macaca nigra)

Genetic analyses based on non-invasively collected samples have become an important tool for evolutionary biology and conservation. Crested macaques (Macaca nigra), endemic to Sulawesi, Indonesia, are important for our understanding of primate evolution as Sulawesi macaques represent an exceptional example of primate adaptive radiation. Crested macaques are also Critically Endangered. However, to date we know very little about their genetics. The aim of our study was to find and validate microsatellite markers useful for evolutionary, conservation and other genetic studies on wild crested macaques. Using faecal samples of 176 wild macaques living in the Tangkoko Reserve, Sulawesi, we identified 12 polymorphic microsatellite loci through cross-species PCR amplification with later modification of some of these primers. We tested their suitability by investigating and exploring patterns of paternity, observed heterozygosity and evidence for inbreeding. We assigned paternity to 63 of 65 infants with high confidence. Among cases with solved paternity, we found no evidence of extra-group paternity and natal breeding. We found a relatively steep male reproductive skew B index of 0.330±0.267; mean±SD) and mean alpha paternity of 65% per year with large variation across groups and years (29-100%). Finally, we detected an excess in observed heterozygosity and no evidence of inbreeding across our three study groups, with an observed heterozygosity of 0.766±0.059 and expected heterozygosity of 0.708±0.059, and an inbreeding coefficient of -0.082±0.035. Our results indicate that the selected markers are useful for genetic studies on wild crested macaques, and possible also other Sulawesi and closely related macaques. They further suggest that the Tangkoko population of crested macaques is still genetically variable despite its small size, isolation and the species’ reproductive patterns. This gives us hope that other endangered primate species living in small, isolated populations may also retain a healthy gene pool, at least in the short term

Rubber Clay Nanocomposites

The use of nanofillers allows the development of nanocomposites with improved properties and novel applications. The technological goal is possible due to the new compounding method that allows a particle dispersion in the nanometer scale increasing the specific surface area.Fil: Cova Sánchez, Mariajose. Instituto Nacional de Tecnología Industrial. Instituto Nacional de Tecnología Industrial - Caucho; Argentina. Universidad Nacional de San Martín. Instituto de Investigación e Ingeniería Ambiental. - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación e Ingeniería Ambiental; ArgentinaFil: Bacigalupe, Alejandro. Universidad Nacional de San Martín. Instituto de Investigación e Ingeniería Ambiental. - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación e Ingeniería Ambiental; Argentina. Instituto Nacional de Tecnología Industrial. Instituto Nacional de Tecnología Industrial - Caucho; ArgentinaFil: Escobar, Mariano Martin. Instituto Nacional de Tecnología Industrial. Instituto Nacional de Tecnología Industrial - Caucho; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mansilla, Marcela Angela. Instituto Nacional de Tecnología Industrial. Instituto Nacional de Tecnología Industrial - Caucho; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin