Dynamic household structure and composition: a manual for longitudinal analysis of living arrangements

OBJECTIVE

This research note introduces a set of tools to conduct analysis of household structure and composition with either limited or comprehensive longitudinal data. The data used here are from Health and Demographic Surveillance Systems in Africa, but the methods can be adapted and applied to other longitudinal micro-data such as register data. A training manual describing the procedures for creating time-varying household measures step-by-step is supplied as supplementary material to this note. Code is provided in STATA but can easily be translated for other statistical software, and the logic for each step remains the same.

RESULTS

The analysis of household structure demonstrates how with limited data (such as a household identifier), it is possible to construct time-varying measures of household membership, including household size or the number of members in specific age and sex groups. The analysis of household composition demonstrates how with expanded data (including links to parents in addition to residence status in the same household), it is possible to construct time-varying measures of household membership of specific kin, i.e. mother, sibling or grandparent. The results illustrated in this research note are a taste of what can be achieved by following the training manual in the supplementary material.

Urban residence and elevated blood pressure among migrant women in South Africa

This paper demonstrates that internal migration may be contributing to rising non-communicable disease risk in low- and middle-income countries in gendered and geographically differentiated ways. With 2018 baseline data from the Migrant Health Follow-Up Study, we investigate the relationship between internal migration and elevated blood pressure (BP) among 2163 rural-origin men and women in South Africa, testing for sex differences. To examine the influence of place, we test whether the migration-BP relationship differs by migrants' destination locations, controlling for household composition, social support, prior migration, and housing quality. We find that migration is associated with elevated BP only among women, and that this association is greatest for migrants living in Tembisa township. Our research underscores that gender and migration are important social determinants of noncommunicable disease risk in low-resource, rapidly-urbanizing settings.

Epidemiology of chronic multimorbidity and temporary migration in a rural South African community in health transition: A cross-sectional population-based analysis

Introduction

In sub-Saharan African settings, the increasing non-communicable disease mortality is linked to migration, which disproportionately exposes sub-populations to risk factors for co-occurring HIV and NCDs.

Methods

We examined the prevalence, patterns, and factors associated with two or more concurrent diagnoses of chronic diseases (i.e., multimorbidity) among temporary within-country migrants. Employing a cross-sectional design, our study sample comprised 2144 residents and non-residents 18-40 years interviewed and with measured biomarkers in 2018 in Wave 1 of the Migrant Health Follow-up Study (MHFUS), drawn from the Agincourt Health and Demographic Surveillance System (AHDSS) in rural north-eastern South Africa. We used modified Poisson regression models to estimate the association between migration status and prevalent chronic multimorbidity conditional on age, sex, education, and healthcare utilisation.

Results

Overall, 301 participants (14%; 95% CI 12.6-15.6), median age 31 years had chronic multimorbidity. Multimorbidity was more prevalent among non-migrants (14.6%; 95% CI 12.8-16.4) compared to migrants (12.8%; 95% CI 10.3-15.7). Non-migrants also had the greatest burden of dual-overlapping chronic morbidities, such as HIV-obesity 5.7%. Multimorbidity was 2.6 times as prevalent (PR 2.65. 95% CI 2.07-3.39) among women compared to men. Among migrants, men, and individuals with secondary or tertiary education manifested lower prevalence of two or more conditions.

Discussion

In a rural community with colliding epidemics, we found low but significant multimorbidity driven by a trio of conditions: HIV, hypertension, and obesity. Understanding the multimorbidity burden associated with early adulthood exposures, including potential protective factors (i.e., migration coupled with education), is a critical first step towards improving secondary and tertiary prevention for chronic disease among highly mobile marginalised sub-populations.

Validity of Self-Report for Ascertaining HIV Status Among Circular Migrants and Permanent Residents in South Africa: A Cross-Sectional, Population-Based Analysis

While expanded HIV testing is needed in South Africa, increasing accurate self-report of HIV status is an essential parallel goal in this highly mobile population. If self-report can ascertain true HIV-positive status, persons with HIV (PWH) could be linked to life-saving care without the existing delays required by producing medical records or undergoing confirmatory testing, which are especially burdensome for the country's high prevalence of circular migrants. We used Wave 1 data from The Migration and Health Follow-Up Study, a representative adult cohort, including circular migrants and permanent residents, randomly sampled from the Agincourt Health and Demographic Surveillance System in a rural area of Mpumalanga Province. Within the analytic sample (n = 1,918), sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of self-report were calculated with dried blood spot (DBS) HIV test results as the standard. Among in-person participants (n = 2,468), 88.8% consented to DBS-HIV testing. HIV prevalence was 25.3%. Sensitivity of self-report was 43.9% (95% CI: 39.5-48.5), PPV was 93.4% (95% CI: 89.5-96.0); specificity was 99.0% (95% CI: 98.3-99.4) and NPV was 83.9% (95% CI: 82.8-84.9). Self-report of an HIV-positive status was predictive of true status for both migrants and permanent residents in this high-prevalence setting. Persons who self-reported as living with HIV were almost always truly positive, supporting a change to clinical protocol to immediately connect persons who say they are HIV-positive to ART and counselling. However, 56% of PWH did not report as HIV-positive, highlighting the imperative to address barriers to disclosure.

The impact of COVID-19 on a cohort of origin residents and internal migrants from South Africa's rural northeast

South Africa has a large temporary migrant population with people commonly moving to metropolitan areas to access employment, while maintaining links with their rural origin households. The COVID-19 pandemic has impacted patterns of movement, livelihoods and health seeking, and the effects on internal, temporary migrants are unclear. Using longitudinal data spanning 2018 to 2020, this paper employs descriptive statistics and regression analyses to assess the impacts of COVID-19 on a cohort of 2971 persons aged 18–40 at baseline, both residents and migrants, from a rural district in South Africa's northeast. In contrast with 2018–2019, in 2020 the share of rural residents initiating a migration decreased by 11 percentage points (p<0.001), while the share of temporary migrants returning to origin households increased by 5 percentage points (p<0.001). Study participants who were continuing migrants reported fewer job losses in comparison with rural-stayers, while 76% of return migrants who were employed in 2019 were no longer employed in 2020. Further, among those who did not experience food shortages in 2019, rural-stayers had 1.42 times the odds of continuing migrants of suffering shortages in 2020. In 2020 health service use in the cohort decreased overall, with return migrants having still lower odds of utilising health services. The results highlight the differential geographic and socioeconomic manifestations of the pandemic, with worsening socioeconomic circumstances observed for rural-staying (disproportionately female) and returning populations, while continuing migrants fared relatively better. It is vital that a COVID-19 response considers the potentially heterogeneous impact of the pandemic on mobile and stable populations. Policy responses may include targeting migrants at their destinations in health promotion of COVID-19 messaging, and strengthening health care and social support in origin communities in recognition that these areas receive return migrants into their catchment population.

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COVID-19 socioeconomic and mobility impacts can be illuminated with longitudinal data.

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Amidst COVID (2020) fewer migrations initiated, and more returns to origin than 2019.

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Strong association found between retained employment and continuing migration.

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Rural-stayers had worsening socioeconomic outcomes compared with continuing migrants.

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Health service use reduced between 2019 and 2020, moreso among return migrants.

The Crucial Role of Mothers and Siblings in Child Survival: Evidence From 29 Health and Demographic Surveillance Systems in Sub-Saharan Africa

A considerable body of research has studied the effects of siblings on child mortality through birth intervals. This research has commonly focused on older siblings. We argue that birth intervals with younger siblings may have equal or stronger effects on child mortality, even during a mother's pregnancy. Moreover, we contend that birth interval effects need to be considered only when siblings are coresident. Using longitudinal data from 29 Health and Demographic Surveillance Systems across sub-Saharan Africa, covering more than 560,000 children, we examine the proximate role of siblings and mothers in child mortality. We find that a birth interval of 24 months or more is advantageous for both older and younger siblings. The effect of a younger sibling on child mortality is more pronounced than that of an older sibling and adds to the effect of an older sibling. Moreover, child mortality is particularly low during a mother's subsequent pregnancy, contrasting the shock resulting from a younger sibling's birth. Further, we find that a mother's or sibling's absence from the household results in a higher risk of mortality, and the death of either reduces child survival up to six months before the death.

Pregnancy-related healthcare utilisation in Agincourt, South Africa, 1993-2018: a longitudinal surveillance study of rural mothers

INTRODUCTION

Pregnancy-related health services, an important mediator of global health priorities, require robust health infrastructure. We described pregnancy-related healthcare utilisation among rural South African women from 1993 to 2018, a period of social, political and economic transition.

METHODS

We included participants enrolled in the Agincourt Health and Socio-Demographic Surveillance System in Mpumalanga Province, South Africa, a population-based longitudinal cohort, who reported pregnancy between 1993 and 2018. We assessed age, antenatal visits, years of education, pregnancy intention, nationality, residency status, previous pregnancies, prepregnancy and postpregnancy contraceptive use, and student status over the study period and modelled predictors of antenatal care utilisation (ordinal), skilled birth attendant presence (logistic) and delivery at a health facility (logistic).

RESULTS

Between 1993 and 2018, 51 355 pregnancies occurred. Median antenatal visits, skilled birth attendant presence and healthcare facility deliveries increased over time. Delivery in 2018 vs 2004 was associated with an increased likelihood of ≥1 additional antenatal visits (adjusted OR (aOR) 10.81, 95% CI 9.99 to 11.71), skilled birth attendant presence (aOR 4.58, 95% CI 3.70 to 5.67) and delivery at a health facility (aOR 3.78, 95% CI 3.15 to 4.54). Women of Mozambican origin were less likely to deliver with a skilled birth attendant (aOR 0.42, 95% CI 0.39 to 0.45) or at a health facility (aOR 0.43, 95% CI 0.41 to 0.46) versus South Africans. Temporary migrants reported fewer antenatal visits (aOR 0.35, 95% CI 0.33 to 0.38) but were more likely to deliver with a skilled birth attendant (aOR 1.91, 95% CI 1.66 to 2.2) or at a health facility (aOR 1.4, 95% CI 1.24 to 1.58) versus permanent residents.

CONCLUSION

Pregnancy-related healthcare utilisation and skilled birth attendant presence at delivery have increased steadily since 1993 in rural northeastern South Africa, aligning with health policy changes enacted during this time. However, mothers of Mozambican descent are still less likely to use free care, which requires further study and policy interventions.

Migrant health penalty: evidence of higher mortality risk among internal migrants in sub-Saharan Africa

Background: Despite the greater attention given to international migration, internal migration accounts for the majority of movements globally. However, research on the effects of internal migration on health is limited, with this relationship examined predominantly in urban settings among working-age adults, neglecting rural populations and younger and older ages.

Objectives: Using longitudinal data from 29 mostly rural sub-Saharan African Health and Demographic Surveillance Systems (HDSS), this study aims to explore life-course differences in mortality according to migration status and duration of residence.

MethodsCox proportional hazards models are employed to analyse the relationship between migration and mortality in the 29 HDSS areas. The analytical sample includes 3 836,173 people and the analysis spans 25 years, from 1990 to 2015. We examine the risk of death by sex across five broad age groups (from ages 1 to 80), and consider recent and past in- and return migrants.

Results: In-migrants have a higher risk of mortality compared to permanent rural residents, with return migrants at greater risk than in-migrants across all age-groups. Female migrants have lower survival chances than males, with greater variability by age. Risk of dying is highest among recent return migrant females aged 30–59: 1.86 (95% CI 1.69–2.06) times that of permanent residents. Only among males aged 15–29 who move to urban areas is there evidence of a ‘healthy migrant’ effect (HR = 0.62, 95% CI 0.51–0.77). There is clear evidence of an adaptation effect across all ages, with the risk of mortality reducing with duration following migration.

Conclusions: Findings suggest that adult internal migrants, particularly females, suffer greater health disadvantages associated with migration. Policy makers should focus on improving migrant’s interface with health services, and support the development of health education and promotion interventions to create awareness of localised health risks for migrants.

Internal migration and health in South Africa: determinants of healthcare utilisation in a young adult cohort

Background

In South Africa, human geographic mobility is high as people engage in both permanent and temporary relocation, predominantly from rural to urban areas. Such mobility can compromise healthcare access and utilisation. The objective of this paper is to explore healthcare utilisation and its determinants in a cohort of internal migrants and permanent residents (non-migrants) originating from the Agincourt sub-district in South Africa’s rural northeast.

Methods

A 5-year cohort study of 3800 individuals aged 18 to 40 commenced in 2017. Baseline data have been collected from 1764 Agincourt residents and 1334 temporary, mostly urban-based, migrants, and are analysed using bivariate analyses, logistic and multinomial regression models, and propensity score matching analysis.

Results

Health service utilisation differs sharply by migrant status and sex. Among those with a chronic condition, migrants had 0.33 times the odds of non-migrants to have consulted a health service in the preceding year, and males had 0.32 times the odds of females of having used health services. Of those who utilised services, migration status was further associated with the type of healthcare utilised, with 97% of non-migrant rural residents having accessed government facilities, while large proportions of migrants (31%) utilised private health services or consulted traditional healers (25%) in migrant destinations. The multinomial logistic regression analysis indicated that, in the presence of controls, migrants had 8.12 the relative risk of non-migrants for utilising private healthcare (versus the government-services-only reference category), and 2.40 the relative risk of non-migrants for using a combination of public and private sector facilities. These findings of differential utilisation hold under statistical adjustment for relevant controls and for underlying propensity to migrate.

Conclusions

Migrants and non-migrants in the study population in South Africa were found to utilise health services differently, both in overall use and in the type of healthcare consulted. The study helps improve upon the limited stock of knowledge on how migrants interface with healthcare systems in low and middle-income country settings. Findings can assist in guiding policies and programmes to be directed more effectively to the populations most in need, and to drive locally adapted approaches to universal health coverage.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-021-10590-6.

A training manual for event history analysis using longitudinal data

Objective

This research note reports on the activities of the Multi-centre Analysis of the Dynamics of Internal Migration And Health (MADIMAH) project aimed at collating and testing of a set of tools to conduct longitudinal event history analyses applied to standardised Health and Demographic Surveillance System (HDSS) datasets. The methods are illustrated using an example of longitudinal micro-data from the Agincourt HDSS, one of a number of open access datasets available through the INDEPTH iShare2 data repository. The research note documents the experience of the MADIMAH group in analysing HDSS data and demonstrates how complex analyses can be streamlined and conducted in an accessible way. These tools are aimed at aiding analysts and researchers wishing to conduct longitudinal data analysis of demographic events.

Results

The methods demonstrated in this research note may successfully be applied by practitioners to longitudinal micro-data from HDSS, as well as retrospective surveys or register data. The illustrations provided are accompanied by detailed, tested computer programs, which demonstrate the full potential of longitudinal data to generate both cross-sectional and longitudinal standard descriptive estimates as well as more complex regression estimates.

Does It Take a Village? Migration among Rural South African Youth

In a rural African context, the saying, "it takes a village to raise a child," suggests that community characteristics are substantially important in children's lives as they transition to adulthood. Are these contextual factors also related to youth migration? Demographers are uncertain about how community characteristics improve our understanding of an individual's propensity to migrate, beyond individual and household factors. In many low and middle-income country settings, youth become migrants for the first time in their lives to provide access to resources that their families need. We employ discrete-time event history models from the 20032011 Agincourt Health and socio-Demographic Surveillance System in rural South Africa to test whether markers of development in a village are associated with the likelihood of youth and young adults migrating, distinguishing between becoming temporary and permanent migrants during this critical life cycle phase. We find that village characteristics indeed differentially predict migration, but not nearly as substantially as might be expected.

Association between internal migration and epidemic dynamics: an analysis of cause-specific mortality in Kenya and South Africa using health and demographic surveillance data

BACKGROUND

Many low- and middle-income countries are facing a double burden of disease with persisting high levels of infectious disease, and an increasing prevalence of non-communicable disease (NCD). Within these settings, complex processes and transitions concerning health and population are underway, altering population dynamics and patterns of disease. Understanding the mechanisms through which changing socioeconomic and environmental contexts may influence health is central to developing appropriate public health policy. Migration, which involves a change in environment and health exposure, is one such mechanism.

METHODS

This study uses Competing Risk Models to examine the relationship between internal migration and premature mortality from AIDS/TB and NCDs. The analysis employs 9 to 14 years of longitudinal data from four Health and Demographic Surveillance Systems (HDSS) of the INDEPTH Network located in Kenya and South Africa (populations ranging from 71 to 223 thousand). The study tests whether the mortality of migrants converges to that of non-migrants over the period of observation, controlling for age, sex and education level.

RESULTS

In all four HDSS, AIDS/TB has a strong influence on overall deaths. However, in all sites the probability of premature death (45q15) due to AIDS/TB is declining in recent periods, having exceeded 0.39 in the South African sites and 0.18 in the Kenyan sites in earlier years. In general, the migration effect presents similar patterns in relation to both AIDS/TB and NCD mortality, and shows a migrant mortality disadvantage with no convergence between migrants and non-migrants over the period of observation. Return migrants to the Agincourt HDSS (South Africa) are on average four times more likely to die of AIDS/TB or NCDs than are non-migrants. In the Africa Health Research Institute (South Africa) female return migrants have approximately twice the risk of dying from AIDS/TB from the year 2004 onwards, while there is a divergence to higher AIDS/TB mortality risk amongst female migrants to the Nairobi HDSS from 2010.

CONCLUSION

Results suggest that structural socioeconomic issues, rather than epidemic dynamics are likely to be associated with differences in mortality risk by migrant status. Interventions aimed at improving recent migrant's access to treatment may mitigate risk.

A training manual for event history data management using Health and Demographic Surveillance System data

OBJECTIVE

The objective of this research note is to introduce a training manual for event history data management. The manual provides a first comprehensive guide to longitudinal Health and Demographic Surveillance System (HDSS) data management that allows for a step-by-step description of the process of structuring and preparing a dataset for the calculation of demographic rates and event history analysis. The research note provides some background information on the INDEPTH Network, and the iShare data repository and describes the need for a manual to guide users as to how to correctly handle HDSS datasets.

RESULTS

The approach outlined in the manual is flexible and can be applied to other longitudinal data sources. It facilitates the development of standardised longitudinal data management and harmonization of datasets to produce a comparative set of results.

Healthy or unhealthy migrants? Identifying internal migration effects on mortality in Africa using health and demographic surveillance systems of the INDEPTH network

Migration has been hypothesised to be selective on health but this healthy migrant hypothesis has generally been tested at destinations, and for only one type of flow, from deprived to better-off areas. The circulatory nature of migration is rarely accounted for. This study examines the relationship between different types of internal migration and adult mortality in Health and Demographic Surveillance System (HDSS) populations in West, East, and Southern Africa, and asks how the processes of selection, adaptation and propagation explain the migration-mortality relationship experienced in these contexts. The paper uses longitudinal data representing approximately 900 000 adults living in nine sub-Saharan African HDSS sites of the INDEPTH Network. Event History Analysis techniques are employed to examine the relationship between all-cause mortality and migration status, over periods ranging from 3 to 14 years for a total of nearly 4.5 million person-years. The study confirms the importance of migration in explaining variation in mortality, and the diversity of the migration-mortality relationship over a range of rural and urban local areas in the three African regions. The results confirm that the pattern of migration-mortality relationship is not exclusively explained by selection but also by propagation and adaptation. Consequences for public health policy are drawn.

Youth migration, livelihood prospects and demographic dividend: A comparison of the Census 2011 and Agincourt Health and Demographic Surveillance System in the rural northeast of South Africa

The 2011 South African national census shows a cohort of young adults comprising an increasing share of the population. This finding is borne out in longitudinal data from the Agincourt Health and Demographic Surveillance System (HDSS). This primarily descriptive paper uses the Agincourt HDSS to examine the migration, employment and unemployment patterns in young adults. The study reveals high levels of temporary labour migration linking rural areas to metropolitan areas and secondary urban places. The type of work conducted by young adults in the Agincourt population is predominantly unskilled labour for both sexes. However, there is some evidence of female employment increasing in more educated sectors. Across all working ages there is pronounced unemployment, but the main pressure is felt by the younger adult population. Education and skills development for both sexes should be strengthened to support the country's efforts to vastly improve labour force participation amongst the youth.

Residential mobility, socioeconomic context and body mass index in a cohort of urban South African adolescents

Adolescents who are changing residence, as well as their social and economic circumstances may experience lifestyle changes that have an effect on body composition outcomes such as undernutrition, overweight or obesity. This paper uses data from Birth to Twenty, a birth cohort of South African urban children, to determine the relationship between residential mobility and body mass index (BMI) amongst Black adolescents aged 15 (n=1613), and to examine the role of changes in household socioeconomic status (SES). The prevalence of overweight and obesity in the sample was 25% in females and 8% in males. Amongst the females, a strong positive association between residential mobility and BMI was observed for those who also experienced an increase in household SES between birth and 15 years (β=0.42, SE=0.13), while no effect was identified for males. The study shows the potential for environmental change and increased resources to influence the risk for obesity. It also highlights the value in considering the range of social environmental factors and changes across the early life course that might play a part in evolving nutritional patterns in urban transitioning environments.

Can C-reactive protein, procalcitonin and mid-regional pro-atrial natriuretic peptide measurements guide choice of in-patient or out-patient care in acute pyelonephritis? Biomarkers In Sepsis (BIS) multicentre study

Whereas C-reactive protein (CRP), procalcitonin (PCT) and mid-regional pro-atrial natriuretic peptide (ANP) may be of use at the bedside in the management of adult patients with infectious disorders, their usefulness has not been established in the setting of acute pyelonephritis. To assess the effectiveness of CRP, PCT and ANP measurements in guiding emergency physicians' decisions whether to admit to hospital patients with acute pyelonephritis, we conducted a multicentre, prospective, observational study in 12 emergency departments in France; 582 consecutive patients were included. The reference standard for admission was defined by experts' advice combined with necessity of admission or death during the 28-day follow-up. Baseline CRP, PCT and ANP were measured and their accuracy in identifying the necessity of admission was analysed using area under curves (AUC) of receiver-operating characteristic (ROC) plots. According to the reference standard, 126 (22%) patients required admission. ANP (AUC 0.75, 95% CI 0.69-0.80) and PCT (AUC 0.75, 95% CI 0.71-0.80) more accurately predicted this than did CRP (AUC 0.69, 95% CI 0.64-0.74). The positive and negative likelihood ratios for each biomarker remained clinically irrelevant whatever the threshold. Our results did not support the use of these markers to help physicians in deciding about admission of patients experiencing acute pyelonephritis in daily practice.

Search for resonant tt[overline] production in pp[overline] collisions at sqrt[s]=1.96 TeV

We report on a search for narrow-width particles decaying to a top and antitop quark pair. The data set used in the analysis corresponds to an integrated luminosity of 680 pb(-1) collected with the Collider Detector at Fermilab in run II. We present 95% confidence level upper limits on the cross section times branching ratio. Assuming a specific top-color-assisted technicolor production model, the leptophobic Z' with width Gamma(Z')=0.012M(Z'), we exclude the mass range M(Z')<725 GeV/c(2) at the 95% confidence level.

South African-ness Among Adolescents: The Emergence of a Collective Identity within the Birth to Twenty Cohort Study

We assessed the emergence of a South African identity among Black, Colored (mixed ancestral origin), White (predominantly English speaking), and Indian adolescents participating in a birth cohort study called "Birth to Twenty" in Johannesburg, South Africa. We examined young people's certainty of their self-categorization as South African, the centrality of their personal, racial and linguistic, and South African identities in their self-definition, and their perceptions of South African life and society today. These results reflect a historical opportunity for full citizenship and national enfranchisement that the end of Apartheid heralded for Black and Colored individuals. Black and Colored youth tend to be more certain about their South African-ness, have a more collective identity, and have a more positive perception around South Africa. In contrast, White and Indian youth are less certain about their South African-ness, have a more individualistic identity, and have a less positive perception about South Africa today.

Search for exclusive gammagamma production in Hadron-Hadron collisions

We have searched for exclusive gammagamma production in proton-antiproton collisions at sqrt[s]=1.96 TeV, using 532 pb(-1) of integrated luminosity taken by the run II Collider Detector at Fermilab. The event signature requires two electromagnetic showers, each with transverse energy E(T)>5 GeV and pseudorapidity |eta|<1.0, with no other particles detected in the event. Three candidate events are observed. We discuss the consistency of the three events with gammagamma, pi(0)pi(0), or eta eta production. The probability that other processes fluctuate to >or=3 events is 1.7x10(-4). An upper limit on the cross section of pp-->p + gammagamma + p production is set at 410 fb with 95% confidence level.

Observation of the Heavy Baryons Sigma b and Sigma b*

We report an observation of new bottom baryons produced in pp collisions at the Tevatron. Using 1.1 fb(-1) of data collected by the CDF II detector, we observe four Lambda b 0 pi+/- resonances in the fully reconstructed decay mode Lambda b 0-->Lambda c + pi-, where Lambda c+-->pK* pi+. We interpret these states as the Sigma b(*)+/- baryons and measure the following masses: m Sigma b+=5807.8 -2.2 +2.0(stat.)+/-1.7(syst.) MeV/c2, m Sigma b- =5815.2+/-1.0(stat.)+/-1.7(syst.) MeV/c2, and m(Sigma b*)-m(Sigma b)=21.2-1.9 +2.0(stat.)-0.3+0.4(syst.) MeV/c2.

Search for chargino-neutralino production in pp collisions at sq rt[s] = 1.96 TeV

We present a search for associated production of the chargino and neutralino supersymmetric particles using up to 1.1 fb{-1} of integrated luminosity collected by the CDF II experiment at the Tevatron pp collider at sq rt[s]=1.96 TeV. We analyze events with a large transverse momentum imbalance and either three charged leptons or two charged leptons of the same electric charge. The numbers of observed events are consistent with standard model expectations. Upper limits on the production cross section are derived in different theoretical models.

Precise measurement of the top-quark mass in the lepton+jets topology at CDF II

We present a measurement of the mass of the top quark from proton-antiproton collisions recorded at the CDF experiment in Run II of the Fermilab Tevatron. We analyze events from the single lepton plus jets final state (tt-->W(+)bW(-)b-->lnubqq'b). The top-quark mass is extracted using a direct calculation of the probability density that each event corresponds to the tt final state. The probability is a function of both the mass of the top quark and the energy scale of the calorimeter jets, which is constrained in situ by the hadronic W boson mass. Using 167 events observed in 955 pb(-1) of integrated luminosity, we achieve the single most precise measurement of the top-quark mass, 170.8+/-2.2(stat.)+/-1.4(syst.) GeV/c(2).

Search for new physics in high-mass electron-positron events in pp[over] collisions at square root s = 1.96 TeV

We report the results of a search for a narrow resonance in electron-positron events in the invariant mass range of 150-950 GeV/c(2) using 1.3 fb(-1) of pp[over] collision data at square root s = 1.96 TeV collected by the CDF II detector at Fermilab. No significant evidence of such a resonance is observed and we interpret the results to exclude the standard-model-like Z' with a mass below 923 GeV/c(2) and the Randall-Sundrum graviton with a mass below 807 GeV/c(2) for k/M[over](pl) = 0.1, both at the 95% confidence level. Combining with diphoton data excludes the Randall-Sundrum graviton for masses below 889 GeV/c(2) for k/M[over](pl) = 0.1.

Search for high-mass diphoton states and limits on Randall-Sundrum gravitons at CDF

We have performed a search for new particles which decay to two photons using 1.2 fb(-1) of integrated luminosity from pp[over] collisions at square root s = 1.96 TeV collected using the CDF II detector at the Fermilab Tevatron. We find the diphoton mass spectrum to be in agreement with the standard model expectation, and set limits on the cross section times branching ratio for the Randall-Sundrum graviton, as a function of diphoton mass. We subsequently derive lower limits for the graviton mass of 230 GeV/c(2) and 850 GeV/c(2), at the 95% confidence level, for coupling parameters (k/M[over](Pl)) of 0.01 and 0.1, respectively.

First measurement of the W-boson mass in run II of the Tevatron

We present a measurement of the W-boson mass using 200 pb{-1} of data collected in pp[over ] collisions at sqrt[s]=1.96 TeV by the CDF II detector at run II of the Fermilab Tevatron. With a sample of 63 964 W-->enu candidates and 51 128 W-->munu candidates, we measure M_{W}=80 413+/-34{stat}+/-34{syst}=80,413+/-48 MeV/c;{2}. This is the most precise single measurement of the W-boson mass to date.

Polarizations of J/psi and psi(2S) mesons produced in pp collisions at square root s = 1.96 TeV

We have measured the polarizations of J/psi and psi(2S) mesons as functions of their transverse momentum p(T) when they are produced promptly in the rapidity range |y| < 0.6 with p(T) > or =5 GeV/c. The analysis is performed using a data sample with an integrated luminosity of about 800 pb(-1) collected by the CDF II detector. For both vector mesons, we find that the polarizations become increasingly longitudinal as p(T) increases from 5 to 30 GeV/c. These results are compared to the predictions of nonrelativistic quantum chromodynamics and other contemporary models. The effective polarizations of J/psi and psi(2S) mesons from B-hadron decays are also reported.

Search for heavy long-lived particles that decay to photons at CDF II

We present the first search for heavy, long-lived particles that decay to photons at a hadron collider. We use a sample of gamma + jet + missing transverse energy events in pp[over] collisions at square root[s] = 1.96 TeV taken with the CDF II detector. Candidate events are selected based on the arrival time of the photon at the detector. Using an integrated luminosity of 570 pb(-1) of collision data, we observe 2 events, consistent with the background estimate of 1.3+/-0.7 events. While our search strategy does not rely on model-specific dynamics, we set cross section limits in a supersymmetric model with [Formula: see text] and place the world-best 95% C.L. lower limit on the [Formula: see text] mass of 101 GeV/c(2) at [Formula: see text].

Observation and mass measurement of the baryon Xib-

We report the observation and measurement of the mass of the bottom, strange baryon Xi(b)- through the decay chain Xi(b)- -->J/psiXi-, where J/psi-->mu+mu-, Xi- -->Lambdapi-, and Lambda-->ppi-. A signal is observed whose probability of arising from a background fluctuation is 6.6 x 10(-15), or 7.7 Gaussian standard deviations. The Xi(b)- mass is measured to be 5792.9+/-2.5(stat) +/- 1.7(syst) MeV/c2.

First measurement of the ratio of central-electron to forward-electron W partial cross sections in pp[over] collisions at (square root)s =1.96 TeV

We present a measurement of sigma(pp[over] --> W) x B(W --> e nu) at (square root)s = 1.96 TeV, using electrons identified in the forward region (1.2 < |eta| < 2.8) of the CDF II detector, in 223 pb(-1) of data. We measure sigma x B = 2796 +/- 13(stat)(-90)(+95)(syst) +/- 162(lum) pb. Combining this result with a previous CDF measurement obtained using electrons in the central region (|eta| approximately < 1), we present the first measurement of the ratio of central-electron to forward-electron W partial cross sections R(exp) = 0.925 +/- 0.006(stat) +/- 0.032(syst), consistent with theoretical predictions using Coordinated Theoretical-Experimental Project on QCD (CTEQ) and Martin-Roberts-Stirling-Thorne (MRST) parton distribution functions.

Measurement of sigma chi c2 B(chi c2-->J/psi gamma)/sigma chi c1 B(chi c1 -->J/psi gamma) in pp collisions at square root s=1.96 TeV

We measure the ratio of cross section times branching fraction, Rp=sigma chi c2 B(chi c2-->J/psi gamma)/sigma chi c1 B(chi c1-->J/psi gamma), in 1.1 fb(-1) of pp collisions at square root s=1.96 TeV. This measurement covers the kinematic range pT(J/psi)>4.0 GeV/c, |eta(J/psi)<1.0, and pT(gamma)>1.0 GeV/c. For events due to prompt processes, we find Rp=0.395+/-0.016(stat)+/-0.015(syst). This result represents a significant improvement in precision over previous measurements of prompt chi c1,2 hadro production.

Inclusive search for new physics with like-sign dilepton events in pp collisions at square root of s =1.96 TeV

We describe a search for anomalous production of events with two leptons (e or mu) of the same electric charge in pp[over ] collisions at a center-of-mass energy of 1.96 TeV. Many extensions to the standard model predict the production of two leptons of the same electric charge. This search has a significant increase in sensitivity compared to earlier searches. Using a data sample corresponding to 1 fb(-1) of integrated luminosity recorded by the CDF II detector, we observe no significant excess in an inclusive selection (expect 33.2+/-4.7 events, observe 44) or in a supersymmetry-optimized selection (expect 7.8+/-1.1 events, observe 13.).

Observation of WZ production

We report the first observation of the associated production of a W boson and a Z boson. This result is based on 1.1 fb;-1 of integrated luminosity from pp collisions at sqrt[s]=1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. We observe 16 WZ candidates passing our event selection with an expected background of 2.7+/-0.4 events. A fit to the missing transverse energy distribution indicates an excess of events compared to the background expectation corresponding to a significance equivalent to 6 standard deviations. The measured cross section is sigma(pp-->WZ)=5.0(-1.6)(+1.8) pb, consistent with the standard model expectation.

Measurement of the top-quark mass in all-hadronic decays in pp collisions at CDF II

We present a measurement of the top-quark mass Mtop in the all-hadronic decay channel tt-->W+bW-b-->q1q2bq3q4b. The analysis is performed using 310 pb-1 of sqrt[s]=1.96 TeV pp[over ] collisions collected with the CDF II detector using a multijet trigger. The mass measurement is based on an event-by-event likelihood which depends on both the sample purity and the value of the top-quark mass, using 90 possible jet-to-parton assignments in the six-jet final state. The joint likelihood of 290 selected events yields a value of Mtop=177.1+/-4.9(stat)+/-4.7(syst) GeV/c2.

Search for anomalous production of multilepton events in pp collisions at sqrt s=1.96 TeV

We report a search for the anomalous production of events with multiple charged leptons in pp[over] collisions at sqrt[s]=1.96 TeV using a data sample corresponding to an integrated luminosity of 346 pb(-1) collected by the CDF II detector at the Fermilab Tevatron. The search is divided into three-lepton and four-or-more-lepton data samples. We observe six events in the three-lepton sample and zero events in the > or =4-lepton sample. Both numbers of events are consistent with standard model background expectations. Within the framework of an R-parity-violating supergravity model, the results are interpreted as mass limits on the lightest neutralino (chi[over](1)(0)) and chargino (chi[over](1+/-) particles. For one particular choice of model parameters, the limits are M(chi[over](1)(0)>110 GeV/c2 and M(chi[over](1+/-)>203 GeV/c2 at 95% confidence level; the variation of these mass limits with model parameters is presented.

Analysis of the quantum numbers J(PC) of the X(3872) particle

We present an analysis of angular distributions and correlations of the X(3872) particle in the exclusive decay mode X(3872)-->J/psipi+ pi- with J/psi-->mu+ mu-. We use 780 pb-1 of data from pp[over ] collisions at sqrt[s]=1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. We derive constraints on spin, parity, and charge conjugation parity of the X(3872) particle by comparing measured angular distributions of the decay products with predictions for different J(PC) hypotheses. The assignments J(PC)=1++ and 2-+ are the only ones consistent with the data.

Measurement of the Lambda b0 lifetime in Lambda b0-->J/psi Lambda 0 in pp collisions at square root s=1.96 TeV

We report a measurement of the Lambda b0 lifetime in the exclusive decay Lambda b0-->J/psi Lambda 0 in pp collisions at square root s=1.96 TeV using an integrated luminosity of 1.0 fb-1 of data collected by the CDF II detector at the Fermilab Tevatron. Using fully reconstructed decays, we measure tau(Lambda b0)=1.593(-0.078)(+0.083)(stat)+/-0.033(syst) ps. This is the single most precise measurement of tau(Lambda b0) and is 3.2sigma higher than the current world average.

Measurement of sigma Lambda b0/sigma B0 x B(Lambda b0-->Lambda c+pi-)/B(B0-->D+pi-) in pp collisions at square root s=1.96 TeV

We present the first observation of the baryon decay Lambda b0-->Lambda c+pi- followed by Lambda c+-->pK-pi+ in 106 pb-1 pp collisions at square root s=1.96 TeV in the CDF experiment. In order to reduce systematic error, the measured rate for Lambda b0 decay is normalized to the kinematically similar meson decay B0-->D+pi- followed by D+-->pi+K-pi+. We report the ratio of production cross sections (sigma) times the ratio of branching fractions (B) for the momentum region integrated above pT>6 GeV/c and pseudorapidity range |eta|<1.3: sigma(pp-->Lambda b0X)/sigma(pp-->B0X)xB(Lambda b0-->Lambda c+pi-)/B(B0-->D+pi-)=0.82+/-0.08(stat)+/-0.11(syst)+/-0.22[B(Lambda c+-->pK-pi+)].

Observation of exclusive electron-positron production in hadron-hadron collisions

We present the first observation of exclusive e(+)e(-) production in hadron-hadron collisions, using pp[over] collision data at (square root) s = 1.96 TeV taken by the run II Collider Detector at Fermilab, and corresponding to an integrated luminosity of 532 pb(-1). We require the absence of any particle signatures in the detector except for an electron and a positron candidate, each with transverse energy E(T) > 5 GeV and pseudorapidity |eta| < 2. With these criteria, 16 events are observed compared to a background expectation of 1.9+/-0.3 events. These events are consistent in cross section and properties with the QED process pp[over] --> p + e(+)e(-) + p[over] through two-photon exchange. The measured cross section is 1.6(-0.3)(+0.5)(stat) +/- 0.3(syst) pb. This agrees with the theoretical prediction of 1.71+/-0.01 pb.

Search for V+A current in top-quark decays in pp collisions at sqrts=1.96 TeV

We report an upper limit on the fraction of V+A current, fV+A, in top-quark decays, using approximately 700 pb-1 of pp[over ] collisions at sqrts=1.96 TeV acquired by the upgraded Collider Detector at Fermilab. For the decay t-->Wb-->lnub (where l=e or micro), the invariant mass of the charged lepton and the bottom quark jet is sensitive to the polarization of the W boson. We determine fV+A=-0.06+/-0.25 given a top-quark mass of 175 GeV/c2. We set an upper limit on fV+A of 0.29 at the 95% confidence level, an improvement by a factor of 2 on the previous best direct limit.

Measurement of the ratios of branching fractions B(B0s --> Ds- pi+ pi+ pi-)/B(B0-->D- pi+ pi+ pi-) and B(B0s --> Ds- pi+)/B(B0-->D- pi+)

Using 355 pb;{-1} of data collected by the CDF II detector in pp[over ] collisions at sqrt[s]=1.96 TeV at the Fermilab Tevatron, we study the fully reconstructed hadronic decays B_{(s)};{0}-->D_{(s)};{-}pi;{+} and B_{(s)};{0}-->D_{(s)};{-}pi;{+}pi;{+}pi;{-}. We present the first measurement of the ratio of branching fractions B(B_{s};{0}-->D_{s};{-}pi;{+}pi;{+}pi;{-})/B(B;{0}-->D;{-}pi;{+}pi;{+}pi;{-})=1.05+/-0.10(stat)+/-0.22(syst). We also update our measurement of B(B_{s};{0}-->D_{s};{-}pi;{+})/B(B;{0}-->D;{-}pi;{+}) to 1.13+/-0.08(stat)+/-0.23(syst), improving the statistical uncertainty by more than a factor of 2. We find B(B_{s};{0}-->D_{s};{-}pi;{+})=[3.8+/-0.3(stat)+/-1.3(syst)]x10;{-3} and B(B_{s};{0}-->D_{s};{-}pi;{+}pi;{+}pi;{-})=[8.4+/-0.8(stat)+/-3.2(syst)]x10;{-3}.

Observation of Bs(0)-Bs(0) oscillations

We report the observation of Bs(0)-Bs(0) oscillations from a time-dependent measurement of the Bs(0)-Bs(0) oscillation frequency Deltams. Using a data sample of 1 fb(-1) of pp collisions at square root of s=1.96 TeV collected with the CDF II detector at the Fermilab Tevatron, we find signals of 5600 fully reconstructed hadronic Bs decays, 3100 partially reconstructed hadronic Bs decays, and 61,500 partially reconstructed semileptonic Bs decays. We measure the probability as a function of proper decay time that the Bs decays with the same, or opposite, flavor as the flavor at production, and we find a signal for Bs(0)-Bs(0) oscillations. The probability that random fluctuations could produce a comparable signal is 8 x 10(-8), which exceeds 5sigma significance. We measure Deltams=17.77 +/- 0.10(stat) +/- 0.07(syst) ps(-1) and extract /V(td)/V(ts)/=0.2060+/-0.0007(Deltams)(-0.0060)(+0.008)(Deltamd+theor).

Observation of B(s)0-->K+ K- and measurements of branching fractions of charmless two-body decays of B0 and B(s)0 mesons in pp collisions at square root of s = 1.96 TeV

We search for decays of the type B(s)0-->h+ h'- (where h,h' = K or pi) in 180 pb(-1) of pp collisions collected at the Tevatron by the upgraded Collider Detector at Fermilab. We report the first observation of the new mode B(s)0-->K+ K- with a yield of 236+/-32 events, corresponding to (fs/fd) x B(B(s)0-->K+ K-)/B(B0-->K+ pi-) = 0.46+/-0.08stat+/-0.07syst, where fs/fd is the ratio of production fractions of B(s)0 and B0. We find results in agreement with world averages for the B0 modes, and set the following new limits at 90% C.L.: B(B(s)0-->K- pi+) < 5.6 x 10(-6) and B(B(s)0-->pi+ pi-) < 1.7 x 10(-6).