Two-dimensional flow of foam around an obstacle: force measurements

A Stokes experiment for foams is proposed. It consists in a two-dimensional flow of a foam, confined between a water subphase and a top plate, around a fixed circular obstacle. We present systematic measurements of the drag exerted by the flowing foam on the obstacle, \emph{versus} various separately controlled parameters: flow rate, bubble volume, bulk viscosity, obstacle size, shape and boundary conditions. We separate the drag into two contributions, an elastic one (yield drag) at vanishing flow rate, and a fluid one (viscous coefficient) increasing with flow rate. We quantify the influence of each control parameter on the drag. The results exhibit in particular a power-law dependence of the drag as a function of the bulk viscosity and the flow rate with two different exponents. Moreover, we show that the drag decreases with bubble size, and increases proportionally to the obstacle size. We quantify the effect of shape through a dimensioned drag coefficient, and we show that the effect of boundary conditions is small.Comment: 26 pages, 13 figures, resubmitted version to Phys. Rev.

Default from tuberculosis treatment in Tashkent, Uzbekistan; Who are these defaulters and why do they default?

<p>Abstract</p> <p>Background</p> <p>In Tashkent (Uzbekistan), TB treatment is provided in accordance with the DOTS strategy. Of 1087 pulmonary TB patients started on treatment in 2005, 228 (21%) defaulted. This study investigates who the defaulters in Tashkent are, when they default and why they default.</p> <p>Methods</p> <p>We reviewed the records of 126 defaulters (cases) and 132 controls and collected information on time of default, demographic factors, social factors, potential risk factors for default, characteristics of treatment and recorded reasons for default.</p> <p>Results</p> <p>Unemployment, being a pensioner, alcoholism and homelessness were associated with default. Patients defaulted mostly during the intensive phase, while they were hospitalized (61%), or just before they were to start the continuation phase (26%). Reasons for default listed in the records were various, 'Refusal of further treatment' (27%) and 'Violation of hospital rules' (18%) were most frequently recorded. One third of the recorded defaulters did not really default but continued treatment under 'non-DOTS' conditions.</p> <p>Conclusion</p> <p>Whereas patient factors such as unemployment, being a pensioner, alcoholism and homelessness play a role, there are also system factors that need to be addressed to reduce default. Such system factors include the obligatory admission in TB hospitals and the inadequately organized transition from hospitalized to ambulatory treatment.</p

Aeration of a Free Jet Above a Spillway

A study of air entrainment above an spillway aerator is presented and discussed with a dimensional analysis. We conclude that similitude of air entrainment processes for spillway aerator is not possible between model and prototype. New informations on the aeration region are presented and an analytical solution of the upper nappe entrainment is developed

Factors associated with default from treatment among tuberculosis patients in nairobi province, Kenya: A case control study

<p>Abstract</p> <p>Background</p> <p>Successful treatment of tuberculosis (TB) involves taking anti-tuberculosis drugs for at least six months. Poor adherence to treatment means patients remain infectious for longer, are more likely to relapse or succumb to tuberculosis and could result in treatment failure as well as foster emergence of drug resistant tuberculosis. Kenya is among countries with high tuberculosis burden globally. The purpose of this study was to determine the duration tuberculosis patients stay in treatment before defaulting and factors associated with default in Nairobi.</p> <p>Methods</p> <p>A Case-Control study; Cases were those who defaulted from treatment and Controls those who completed treatment course between January 2006 and March 2008. All (945) defaulters and 1033 randomly selected controls from among 5659 patients who completed treatment course in 30 high volume sites were enrolled. Secondary data was collected using a facility questionnaire. From among the enrolled, 120 cases and 154 controls were randomly selected and interviewed to obtain primary data not routinely collected. Data was analyzed using SPSS and Epi Info statistical software. Univariate and multivariate logistic regression analysis to determine association and Kaplan-Meier method to determine probability of staying in treatment over time were applied.</p> <p>Results</p> <p>Of 945 defaulters, 22.7% (215) and 20.4% (193) abandoned treatment within first and second months (intensive phase) of treatment respectively. Among 120 defaulters interviewed, 16.7% (20) attributed their default to ignorance, 12.5% (15) to traveling away from treatment site, 11.7% (14) to feeling better and 10.8% (13) to side-effects. On multivariate analysis, inadequate knowledge on tuberculosis (OR 8.67; 95% CI 1.47-51.3), herbal medication use (OR 5.7; 95% CI 1.37-23.7), low income (OR 5.57, CI 1.07-30.0), alcohol abuse (OR 4.97; 95% CI 1.56-15.9), previous default (OR 2.33; 95% CI 1.16-4.68), co-infection with Human immune-deficient Virus (HIV) (OR 1.56; 95% CI 1.25-1.94) and male gender (OR 1.43; 95% CI 1.15-1.78) were independently associated with default.</p> <p>Conclusion</p> <p>The rate of defaulting was highest during initial two months, the intensive phase of treatment. Multiple factors were attributed by defaulting patients as cause for abandoning treatment whereas several were independently associated with default. Enhanced patient pre-treatment counseling and education about TB is recommended.</p

Risk factors for tuberculosis treatment failure, default, or relapse and outcomes of retreatment in Morocco

<p>Abstract</p> <p>Background</p> <p>Patients with tuberculosis require retreatment if they fail or default from initial treatment or if they relapse following initial treatment success. Outcomes among patients receiving a standard World Health Organization Category II retreatment regimen are suboptimal, resulting in increased risk of morbidity, drug resistance, and transmission.. In this study, we evaluated the risk factors for initial treatment failure, default, or early relapse leading to the need for tuberculosis retreatment in Morocco. We also assessed retreatment outcomes and drug susceptibility testing use for retreatment patients in urban centers in Morocco, where tuberculosis incidence is stubbornly high.</p> <p>Methods</p> <p>Patients with smear- or culture-positive pulmonary tuberculosis presenting for retreatment were identified using clinic registries in nine urban public clinics in Morocco. Demographic and outcomes data were collected from clinical charts and reference laboratories. To identify factors that had put these individuals at risk for failure, default, or early relapse in the first place, initial treatment records were also abstracted (if retreatment began within two years of initial treatment), and patient characteristics were compared with controls who successfully completed initial treatment without early relapse.</p> <p>Results</p> <p>291 patients presenting for retreatment were included; 93% received a standard Category II regimen. Retreatment was successful in 74% of relapse patients, 48% of failure patients, and 41% of default patients. 25% of retreatment patients defaulted, higher than previous estimates. Retreatment failure was most common among patients who had failed initial treatment (24%), and default from retreatment was most frequent among patients with initial treatment default (57%). Drug susceptibility testing was performed in only 10% of retreatment patients. Independent risk factors for failure, default, or early relapse after initial treatment included male gender (aOR = 2.29, 95% CI 1.10-4.77), positive sputum smear after 3 months of treatment (OR 7.14, 95% CI 4.04-13.2), and hospitalization (OR 2.09, 95% CI 1.01-4.34). Higher weight at treatment initiation was protective. Male sex, substance use, missed doses, and hospitalization appeared to be risk factors for default, but subgroup analyses were limited by small numbers.</p> <p>Conclusions</p> <p>Outcomes of retreatment with a Category II regimen are suboptimal and vary by subgroup. Default among patients receiving tuberculosis retreatment is unacceptably high in urban areas in Morocco, and patients who fail initial tuberculosis treatment are at especially high risk of retreatment failure. Strategies to address risk factors for initial treatment default and to identify patients at risk for failure (including expanded use of drug susceptibility testing) are important given suboptimal retreatment outcomes in these groups.</p

Factors Associated with Tuberculosis Treatment Default in an Endemic Area of the Brazilian Amazon: A Case Control-Study

SETTING: Treatment default is a serious problem in tuberculosis control because it implies persistence of infection source, increased mortality, increased relapse rates and facilitates the development of resistant strains. OBJECTIVE: This study analyzed tuberculosis treatment default determinants in the Amazonas State to contribute in planning appropriate control interventions. DESIGN: Observational study with a retrospective cohort using Brazilian Disease Notification System data from 2005 to 2010. A nested case control study design was used. Patients defaulting from treatment were considered as 'cases' and those completing treatment as 'controls'. In the analysis, 11,312 tuberculosis patients were included, 1,584 cases and 9,728 controls. RESULTS: Treatment default was observed to be associated to previous default (aOR 3.20; p<0.001), HIV positivity (aOR 1.62; p<0.001), alcoholism (aOR 1.51; p<0.001), low education level (aOR 1.35; p<0.001) and other co-morbidities (aOR 1.31; p = 0.05). Older patients (aOR 0.98; p = 0.001) and DOT (aOR 0,72; p<0.01) were considered as protective factor for default. CONCLUSIONS: Associated factors should be considered in addressing care and policy actions to tuberculosis control. Information on disease and treatment should be intensified and appropriate to the level of education of the population, in order to promote adherence to treatment and counter the spread of multidrug resistance to anti-TB drugs

Barriers and enablers in the management of tuberculosis treatment in Addis Ababa, Ethiopia: a qualitative study

Tuberculosis (TB) is an infectious disease which causes about two million deaths each year. In 1993, the World Health Organization (WHO) declared TB to be a “Global Emergency” due to an increasing number of TB cases and a rise in multidrug resistant cases in the developed world. Treatment interruption was considered one of the major challenges. WHO introduced the current TB control program DOTS (directly observed treatment, short course) as the tool to control the disease. To prevent further development of resistance against anti-TB drugs it was decided to observe each patient taking their daily dose of medication. The overall aim of this thesis is to explore how patients and health workers perceive and manage TB symptoms and treatment in a high-endemic and a low-endemic setting in the era of DOT(S). The data is based on fieldwork, including in-depth interviews and focus groups with TB patients and health workers, in Addis Ababa, Ethiopia (2001-2002) and in Oslo/Akershus, Norway (2007-2008). We found that people’s interpretation and management of TB symptoms is influenced by cultural, social and economic factors. TB was, in both contexts, associated with poverty, and subsequently with a disease that affects certain countries or certain segments of a population. TB was viewed as a severe disease in both contexts, but there was variation between individuals to what extent one considered oneself as a likely victim. In the absence of circumstantial causes, such as poverty, patients in a lowendemic setting like Norway, found it difficult to understand why they had developed the disease. There was scarce knowledge about the fact that the disease could be latent. Awareness of early symptoms, such as persistent cough, was low in both contexts. Perceptions of vulnerability, together with the presence or absence of socio-economic barriers or enablers influenced at what time patients would seek help. The study suggests that health personnel lacked awareness or misinterpreted early symptoms of TB. In Ethiopia, lay categorizations of early TB symptoms converged with diagnostic practices in parts of the professional health sector. The diagnostic process could endure for many months after patients’ first contact with the health services. Similarly, in Norway, we found that patients’ interpretations of early symptoms often were confirmed in the meeting with health personnel. The consequences were prolonged diagnostic processes. The study shows that patients’ ability to manage TB treatment is a product of dynamic processes, in which social and economic costs and other burdens interplay over time. A decision to interrupt treatment can be shaped by past struggles and accrued costs; in which seems financially, socially or emotionally unbearable at the moment of treatment interruption. The burdens related to DOT could also be significant, in patients who did not interrupt treatment. Patients in both Ethiopia and Norway experienced an authoritarian and rigid practice of DOT, which made it difficult to simultaneously attend to demands related to treatment and demands related to other areas of life. The most vulnerable patients, such as those without permanent jobs, suffered from high economic, social and emotional costs. In conclusion, health personal need more knowledge about typical and atypical symptoms of TB. In low-endemic settings doctors need to be trained to adjust their level of suspicion to the migration history of the patient. In high-endemic settings one should be aware that health personnel may understand and manage TB within a traditional perspective. Patients in both high- and low-endemic contexts need concrete information about the cause of TB, how it is transmitted, how symptoms can be manifested, how the disease can progress and how it can be cured. The study indicates that inequalities that predispose for TB may be reinforced in the patient’s interaction with the health services due to a rigid, disempowering practice of DOT. Subsequently, DOT per se may add to the chain of structural barriers that patients have to overcome to access and complete treatment. To ensure that TB patients complete treatment one must address the coexisting and interacting crises that follow a TB diagnosis. This could require TB programs to adopt a more holistic approach. Measures that secure early diagnosis may reduce some of the physical, psycho-social and economic costs patients face while undergoing treatment. Measures that empower patients to participate in their own health care may avoid disempowering and humiliating practices

To change or not to change experimenters: Caveats for repeated behavioural and physiological measures in Montagu's Harrier

International audienceAnimals facing anthropogenic disturbances may exhibit different anti‐predator responses depending on their perception of the risk. Experimental measures of behavioural and physiological traits may be impacted by the disturbance due to experimenter handlings and activities. In this study, we assessed the behavioural and physiological responses of Montagu's harrier chicks (Circus pygargus) from 14 nests, visited four times from hatching to fledgling by either the same (group I) or different (group NI) experimenters. Escape, aggressiveness and stress‐induced corticosterone concentration increased for both groups over time but chicks from group I showed a higher increase in their behavioural and physiological responses than chicks from group NI. This increase occurred after the second visit when experimenters took the first blood sampling on nestlings. Handling by the same experimenters throughout the study did not result in habituation but in sensitization. Our results suggest that Montagu's harrier nestlings may discriminate between the people who visit their nests and respond to experimenters’ identity. Therefore, we urge researchers working on behaviour and/or the physiology of stress including repeated measurements (such as animal personality studies for instance) to consider whether the experiments should or should not be realized by the same experimenters (as usually done to minimize bias) as it can influence the outcomes of the experiments