Challenging the Standard Model by high precision comparisons of the fundamental properties of antiprotons and protons

This thesis describes high precision measurements on the fundamental properties of the antiproton, namely the charge-to-mass ratio and the magnetic moment. This work is embedded in the experimental work of the BASE collaboration (Baryon Antibaryon Symmetry Experiment). BASE operates a sophisticated cryogenic Multi-Penning trap system in the Antiproton Decelerator facility at CERN. One main result of this thesis are significant technical improvements of the apparatus, which reduced the limitation of shot-to-shot cyclotron frequency scatter by a factor of more than five compared to earlier work. With this improved apparatus, a measurement campaign on the antiproton-to-proton charge-to-mass ratio with a statistical uncertainty of 20×10−12 and an overall uncertainty of about 35 × 10−12 was conducted. This campaign was part of a series of charge-to-mass ratio measurements on the antiproton with the overall goal to significantly improve the previous best measurement conducted by BASE in 2014, which yielded a fractional uncertainty of 69×10−12. In this thesis, also the first dedicated heating rate measurement in a cryogenic Penning trap experiment is described. Here, the lowest heating rates ever reported for an ion trap were observed. As part of this thesis, phase sensitive methods for measuring the cyclotron frequency of a single trapped ion were implemented in the BASE experiment. These methods allowed to measure the cyclotron frequency with a shot-to-shot scatter improved by a factor of five compared to methods used in previous experiments. The significant improvements in cyclotron frequency scatter open up the possibility to measure the antiproton magnetic moment and the antiproton charge-to-mass ratio with much increased precision, and thereby enable more stringent tests of the fundamental CPT symmetry by direct comparisons of matter/antimatter conjugates

Reproductive health services for refugees by refugees in Guinea I: family planning.

BACKGROUND: Comprehensive studies of family planning (FP) in refugee camps are relatively uncommon. This paper examines gender and age differences in family planning knowledge, attitudes, and practices among Sierra Leonean and Liberian refugees living in Guinea. METHODS: In 1999, a cross-sectional survey was conducted of 889 reproductive-age men and women refugees from 48 camps served by the refugee-organised Reproductive Health Group (RHG). Sampling was multi-stage with data collected for socio-demographics, family planning, sexual health, and antenatal care. Statistics were calculated for selected indicators. RESULTS: Women knew more about FP, although men's education reduced this difference. RHG facilitators were the primary source of reproductive health information for all respondents. However, more men then women obtained information from non-health sources, such as friends and media. Approval of FP was high, significantly higher in women than in men (90% vs. 70%). However, more than 40% reported not having discussed FP with their partner. Perceived service quality was an important determinant in choosing where to get contraceptives. Contraceptive use in the camps served by RHG was much higher than typical for either refugees' country of origin or the host country (17% vs. 3.9 and 4.1% respectively), but the risk of unwanted pregnancy remained considerable (69%). CONCLUSION: This refugee self-help model appeared largely effective and could be considered for reproductive health needs in similar settings. Having any formal education appeared a major determinant of FP knowledge for men, while this was less noticeable for women. Thus, FP communication strategies for refugees should consider gender-specific messages and channels

High prevalence of IgG antibodies to Ebola virus in the Efe pygmy population in the Watsa region, Democratic Republic of the Congo

Background: Factors related to the natural transmission of Ebola virus (EBOV) to humans are still not well defined. Results of previous sero-prevalence studies suggest that circulation of EBOV in human population is common in sub-Saharan Africa. The Efe pygmies living in Democratic Republic of the Congo are known to be exposed to potential risk factors of EBOV infection such as bush meat hunting, entry into caves, and contact with bats. We studied the pygmy population of Watsa region to determine seroprevalence to EBOV infection and possible risks factors. Method: Volunteer participants (N = 300) aged 10 years or above were interviewed about behavior that may constitute risk factors for transmission of EBOV, including exposures to rats, bats, monkeys and entry into caves. Samples of venous blood were collected and tested for IgG antibody against EBOV by enzyme-linked immunosorbent assay (ELISA). The chi(2)-test and Fisher's exact test were used for the comparison of proportions and the Student's t-test to compare means. The association between age group and anti-EBOV IgG prevalence was analysed by a nonparametric test for trend. Results: The prevalence of anti-EBOV IgG was 18.7 % overall and increased significantly with age (p = 0.023). No association was observed with exposure to risk factors (contacts with rats, bats, monkeys, or entry into caves). Conclusions: The seroprevalence of IgG antibody to EBOV in pygmies in Watsa region is among the highest ever reported, but it remains unclear which exposures might lead to this high infection rate calling for further ecological and behavioural studies

HIV knowledge, risk perception and avoidant behaviour change among Sierra Leonean refugees in Guinea.

A common assumption underpinning health communications design in humanitarian settings is that increasing knowledge and risk perception will lead to appropriate behaviour change. This study compares associations of HIV knowledge and perceived risk with reported HIV-avoidant behaviour changes and sexual health choices from a community survey of 698 sexually experienced male and female Sierra Leonean refugees in Guinea. HIV knowledge was not significantly associated with reported HIV-avoidant changes (OR 1.25; adjusted for gender; 95%CI 0.76-2.04), while perceived HIV risk was negatively associated (OR 0.38, adjusted for age at sexual debut; 95%CI 0.22-0.66). Trying to conceive was the main reason reported for not using condoms or other contraception (28%; 138/498), followed by current pregnancy/lactation (19%; 93/498). Results suggest contextual factors (e.g. desire for children) can be as important as knowledge and risk-perception, and HIV prevention initiatives in stable and chronic humanitarian settings should account for these

Reproductive health for refugees by refugees in Guinea IV: Peer education and HIV knowledge, attitudes, and reported practices

BACKGROUND: Both conflict and HIV affect sub-Saharan Africa, and supportive approaches for HIV prevention among refugees are crucial. Peer education has been associated with improved HIV outcomes, though relatively little research has been published on refugee settings. The primary objective of this study was to assess whether exposure to refugee peer education was associated with improved HIV knowledge, attitudes, or practice outcomes among refugees in Guinea. Secondary objectives were to assess whether gender, age, or formal education were more strongly associated than peer education with improved HIV outcomes. METHODS: Data was collected by cross-sectional survey from 889 reproductive-age men and women in 23 camps in the Forest Region of Guinea. Selected exposures (i.e. peer education, gender, formal education, age) were analysed for associations with HIV outcomes using logistic regression odds ratios (OR). RESULTS: Most participants (88%) had heard of HIV, particularly those exposed to peer or formal education. Most correctly identified ways to protect themselves, while maintaining misconceptions about HIV transmission. Women and those exposed to either peer or formal education had significantly fewer misconceptions. Half of participants considered themselves at risk of HIV, women with 52% higher odds than men (adjusted OR 1.52, 95%CI 1.01-2.29). Participants exposed to peer education had more than twice the odds of reporting having made HIV-avoidant behavioural changes than unexposed participants (72% versus 58%; adjusted OR 2.49, 95%CI 1.52-4.08). While women had 57% lower odds than men of reporting HIV-avoidant behavioural changes (OR 0.43, 95%CI 0.31-0.60), women exposed to peer education had greater odds than exposed men of reporting HIV-avoidant changes (OR 2.70 versus OR 1.95). Staying faithful (66%) was the most frequent behavioural change reported. CONCLUSIONS: Peer education was most strongly associated with reported HIV-avoidant behaviour change. Gender was most associated with HIV knowledge and risk perception. Refugee women had fewer misconceptions than men had, but were more likely to report HIV risk and less likely to report making behavioural changes. Peer education appears promising for HIV interventions in chronic-emergency settings, if gender disparities and related barriers to condom usage are also addressed

Marburg hemorrhagic fever in Durba and Watsa, Democratic Republic of the Congo: clinical documentation, features of illness, and treatment

The objective of the present study was to describe day of onset and duration of symptoms of Marburg hemorrhagic fever (MHF), to summarize the treatments applied, and to assess the quality of clinical documentation. Surveillance and clinical records of 77 patients with MHF cases were reviewed. Initial symptoms included fever, headache, general pain, nausea, vomiting, and anorexia (median day of onset, day 1-2), followed by hemorrhagic manifestations (day 5-8+), and terminal symptoms included confusion, agitation, coma, anuria, and shock. Treatment in isolation wards was acceptable, but the quality of clinical documentation was unsatisfactory. Improved clinical documentation is necessary for a basic evaluation of supportive treatment

Signs and Symptoms, Management and Outcomes

Data collected during the 2012 Ebola virus disease (EVD) epidemic in the Democratic Republic of the Congo were analysed for clinical signs, symptoms and case fatality of EVD caused by Bundibugyo virus (BDBV), establishment of differential diagnoses, description of medical treatment and evaluation of the quality of clinical documentation. In a quantitative observational prospective study, global epidemiological data from 52 patients (34 patients within the community, 18 patients treated in the Ebola Treatment Centre) were entered anonymously into a database, subsequently matched and analysed. Relevant findings include an over-representation of females among community EVD cases (85.3%) and of community EVD cases in the age group of 15-54 years (82.4%). All ETC patients had fever (55.6% of all 18 ETC patients during their hospital stay) or self-reported fever (88.2% upon admission) at some point of time during their illness. Major symptoms of ETC patients during hospital stay included asthenia (82.4%), anorexia (82.4%), myalgia (70.6%), sore throat/difficulty swallowing (70.6%), arthralgia (76.5%) and nausea (70.6%). Gastrointestinal signs and symptoms (nausea, diarrhoea, vomiting) (76.4%) as well as general pain (94.1%) were frequent in ETC patients. The median duration of EVD was 18 days, while the mean incubation period was 11.3 days. Differential diagnosis of EVD included malaria (28.3%), intestinal parasitosis (10.9%), and infectious syndrome (10.9%). There was also an important variation in clinical evolvement. Quality of documentation was adversely affected by the way patient file contents were transferred from inside to outside the high-risk zone, entailing a mean mismatch value of 27.3% between patient file contents inside vs. outside the high-risk zone. This study adds further description of EVD (frequently non-specific signs and symptoms, non frequent bleeding, a long incubation period, long duration of disease) and emphasizes the need for improving clinical monitoring and documentation in EVD outbreak settings

Factors Associated with Marburg Hemorrhagic Fever:

Background. Reliable on-site polymerase chain reaction (PCR) testing for Marburg hemorrhagic fever (MHF) is not always available. Therefore, clinicians triage patients on the basis of presenting symptoms and contact history. Using patient data collected in Uige, Angola, in 2005, we assessed the sensitivity and specificity of these factors to evaluate the validity of World Health Organization (WHO)–recommended case definitions for MHF. Methods. Multivariable logistic regression was used to identify independent predictors of PCR confirmation of MHF. A data-derived algorithm was developed to obtain new MHF case definitions with improved sensitivity and specificity. Results. A MHF case definition comprising (1) an epidemiological link or (2) the combination of myalgia or arthralgia and any hemorrhage could potentially serve as an alternative to current case definitions. Our dataderived case definitions maintained the sensitivity and improved the specificity of current WHO-recommended case definitions. Conclusions. Continued efforts to improve clinical documentation during filovirus outbreaks would aid in the refinement of case definitions and facilitate outbreak control

Ebola Virus Disease Outbreak in Isiro, Democratic Republic of the Congo, 2012: Signs and Symptoms, Management and Outcomes

Data collected during the 2012 Ebola virus disease (EVD) epidemic in the Democratic Republic of the Congo were analysed for clinical signs, symptoms and case fatality of EVD caused by Bundibugyo virus (BDBV), establishment of differential diagnoses, description of medical treatment and evaluation of the quality of clinical documentation. In a quantitative observational prospective study, global epidemiological data from 52 patients (34 patients within the community, 18 patients treated in the Ebola Treatment Centre) were entered anonymously into a database, subsequently matched and analysed. Relevant findings include an over-representation of females among community EVD cases (85.3%) and of community EVD cases in the age group of 15-54 years (82.4%). All ETC patients had fever (55.6% of all 18 ETC patients during their hospital stay) or self-reported fever (88.2% upon admission) at some point of time during their illness. Major symptoms of ETC patients during hospital stay included asthenia (82.4%), anorexia (82.4%), myalgia (70.6%), sore throat/difficulty swallowing (70.6%), arthralgia (76.5%) and nausea (70.6%). Gastrointestinal signs and symptoms (nausea, diarrhoea, vomiting) (76.4%) as well as general pain (94.1%) were frequent in ETC patients. The median duration of EVD was 18 days, while the mean incubation period was 11.3 days. Differential diagnosis of EVD included malaria (28.3%), intestinal parasitosis (10.9%), and infectious syndrome (10.9%). There was also an important variation in clinical evolvement. Quality of documentation was adversely affected by the way patient file contents were transferred from inside to outside the high-risk zone, entailing a mean mismatch value of 27.3% between patient file contents inside vs. outside the high-risk zone. This study adds further description of EVD (frequently non-specific signs and symptoms, non frequent bleeding, a long incubation period, long duration of disease) and emphasizes the need for improving clinical monitoring and documentation in EVD outbreak settings