Equation-Based Congestion Control for Unicast Applications: the Extended Version

This paper proposes a mechanism for equation-based congestion control for unicast traffic. Most best-effort traffic in the current Internet is well-served by the dominant transport protocol TCP. However, traffic such as best-effort unicast streaming multimedia could find use for a TCP-friendly congestion control mechanism that refrains from reducing the sending rate in half in response to a single packet drop. With our mechanism, the sender explicitly adjusts its sending rate as a function of the measured rate of loss events, where a loss event consists of one or more packets dropped within a single round-trip time. We use both simulations and experiments over the Internet to explore performance. Equation-based congestion control is also a promising avenue of development for congestion control of multicast traffic, and so an additional reason for this work is to lay a sound basis for the later development of multicast congestion control

Indigenous Midwives and the Biomedical System among the Karamojong of Uganda: Introducing the Partnership Paradigm

Certainly there can be no argument against every woman being attended at birth by a skilled birth attendant. Currently, as elsewhere, the Ugandan government favors a biomedical model of care to achieve this aim, even though the logistical realities in certain regions mitigate against its realisation. This article addresses the Indigenous midwives of the Karamojong tribe in Northeastern Uganda and their biosocial model of birth, and describes the need British midwife Sally Graham, who lived and worked with the Karamojong for many years, identified to facilitate “mutual accommodation” between biomedical staff and these midwives, who previously were reluctant to refer women to the hospital that serves their catchment area due to maltreatment by the biomedical practitioners there. This polarisation of service does not meet that society’s needs. We do not argue for the provision of a unilateral, top-down educational service, but rather for one that collaborates between the biosocial model of the Karamojong and the biomedical model supported by government legislation. We show that such a partnership is practical, safer, and harnesses the best and most economical and effective use of resources. In this article, we demonstrate the roles of the Indigenous midwives/traditional birth attendants (TBAs) and show that not only is marriage of the two systems both possible and desirable, but is also essential for meeting the needs of Karamojong women. The TBA is frequently all the skilled assistance available to these women, particularly during the rainy season when roads are impassable in rural South Karamoja. Without this skilled help, the incidence of maternal and infant mortality would undoubtedly increase. Ongoing training and supervision of the TBA/Indigenous midwife in best practices will ensure better care. We offer a way forward via the Partnership Paradigm (PP) that lead author Sally Graham designed in conjunction with the Indigenous midwives and biomedical staff with whom she worked, the development and characteristics of which this article describes

Controlling High Bandwidth Aggregates in the Network

The current Internet infrastructure has very few built-in protection mechanisms, and is therefore vulnerable to attacks and failures. In particular, recent events have illustrated the Internet's vulnerability to both denial of service (DoS) attacks and flash crowds in which one or more links in the network (or servers at the edge of the network) become severely congested. In both DoS attacks and flash crowds the congestion is due neither to a single flow, nor to a general increase in traffic, but to a well-defined subset of the traffic --- an aggregate. This paper proposes mechanisms for detecting and controlling such high bandwidth aggregates. Our design involves both a local mechanism for detecting and controlling an aggregate at a single router, and a cooperative pushback mechanism in which a router can ask upstream routers to control an aggregate. While certainly not a panacea, these mechanisms could provide some needed relief from flash crowds and flooding-style DoS attacks. The presentation in this paper is a first step towards a more rigorous evaluation of these mechanisms

Persistence of the immune response induced by BCG vaccination.

BACKGROUND: Although BCG vaccination is recommended in most countries of the world, little is known of the persistence of BCG-induced immune responses. As novel TB vaccines may be given to boost the immunity induced by neonatal BCG vaccination, evidence concerning the persistence of the BCG vaccine-induced response would help inform decisions about when such boosting would be most effective. METHODS: A randomised control study of UK adolescents was carried out to investigate persistence of BCG immune responses. Adolescents were tested for interferon-gamma (IFN-gamma) response to Mycobacterium tuberculosis purified protein derivative (M.tb PPD) in a whole blood assay before, 3 months, 12 months (n = 148) and 3 years (n = 19) after receiving teenage BCG vaccination or 14 years after receiving infant BCG vaccination (n = 16). RESULTS: A gradual reduction in magnitude of response was evident from 3 months to 1 year and from 1 year to 3 years following teenage vaccination, but responses 3 years after vaccination were still on average 6 times higher than before vaccination among vaccinees. Some individuals (11/86; 13%) failed to make a detectable antigen-specific response three months after vaccination, or lost the response after 1 (11/86; 13%) or 3 (3/19; 16%) years. IFN-gamma response to Ag85 was measured in a subgroup of adolescents and appeared to be better maintained with no decline from 3 to 12 months. A smaller group of adolescents were tested 14 years after receiving infant BCG vaccination and 13/16 (81%) made a detectable IFN-gamma response to M.tb PPD 14 years after infant vaccination as compared to 6/16 (38%) matched unvaccinated controls (p = 0.012); teenagers vaccinated in infancy were 19 times more likely to make an IFN-gamma response of > 500 pg/ml than unvaccinated teenagers. CONCLUSION: BCG vaccination in infancy and adolescence induces immunological memory to mycobacterial antigens that is still present and measurable for at least 14 years in the majority of vaccinees, although the magnitude of the peripheral blood response wanes from 3 months to 12 months and from 12 months to 3 years post vaccination. The data presented here suggest that because of such waning in the response there may be scope for boosting anti-tuberculous immunity in BCG vaccinated children anytime from 3 months post-vaccination. This supports the prime boost strategies being employed for some new TB vaccines currently under development

Quantifying MCPA load pathways at catchment scale using high temporal resolution data

peer-reviewedDetection of the agricultural acid herbicide MCPA (2-methyl-4-chlorophenoxyacetic acid) in drinking water source catchments is of growing concern, with economic and environmental implications for water utilities and wider ecosystem services. MCPA is poorly adsorbed to soil and highly mobile in water, but hydrological pathway processes are relatively unknown at the catchment scale and limited by coarse resolution data. This understanding is required to target mitigation measures and to provide a framework to monitor their effectiveness. To address this knowledge gap, this study reports findings from river discharge and synchronous MCPA concentration datasets (continuous 7 hour and with additional hourly sampling during storm events) collected over a 7 month herbicide spraying season. The study was undertaken in a surface (source) water catchment (384 km2—of which 154 km2 is agricultural land use) in the cross-border area of Ireland. Combined into loads, and using two pathway separation techniques, the MCPA data were apportioned into event and baseload components and the former was further separated to quantify a quickflow (QF) and other event pathways. Based on the 7 hourly dataset, 85.2 kg (0.22 kg km−2 by catchment area, or 0.55 kg km−2 by agricultural area) of MCPA was exported from the catchment in 7 months. Of this load, 87.7 % was transported via event flow pathways with 72.0 % transported via surface dominated (QF) pathways. Approximately 12 % of the MCPA load was transported via deep baseflows, indicating a persistence in this delayed pathway, and this was the primary pathway condition monitored in a weekly regulatory sampling programme. However, overall, the data indicated a dominant acute, storm dependent process of incidental MCPA loss during the spraying season. Reducing use and/or implementing extensive surface pathway disconnection measures are the mitigation options with greatest potential, the success of which can only be assessed using high temporal resolution monitoring techniques

An exploration of influences on women’s birthplace decision-making in New Zealand: a mixed methods prospective cohort within the Evaluating Maternity Units study

BACKGROUND: There is worldwide debate surrounding the safety and appropriateness of different birthplaces for well women. One of the primary objectives of the Evaluating Maternity Units prospective cohort study was to compare the clinical outcomes for well women, intending to give birth in either an obstetric-led tertiary hospital or a free-standing midwifery-led primary maternity unit. This paper addresses a secondary aim of the study – to describe and explore the influences on women’s birthplace decision-making in New Zealand, which has a publicly funded, midwifery-led continuity of care maternity system. METHODS: This mixed method study utilised data from the six week postpartum survey and focus groups undertaken in the Christchurch area in New Zealand (2010–2012). Christchurch has a tertiary hospital and four primary maternity units. The survey was completed by 82% of the 702 study participants, who were well, pregnant women booked to give birth in one of these places. All women received midwifery-led continuity of care, regardless of their intended or actual birthplace. RESULTS: Almost all the respondents perceived themselves as the main birthplace decision-makers. Accessing a ‘specialist facility’ was the most important factor for the tertiary hospital group. The primary unit group identified several factors, including ‘closeness to home’, ‘ease of access’, the ‘atmosphere’ of the unit and avoidance of ‘unnecessary intervention’ as important. Both groups believed their chosen birthplace was the right and ‘safe’ place for them. The concept of ‘safety’ was integral and based on the participants’ differing perception of safety in childbirth. CONCLUSIONS: Birthplace is a profoundly important aspect of women’s experience of childbirth. This is the first published study reporting New Zealand women’s perspectives on their birthplace decision-making. The groups’ responses expressed different ideologies about childbirth. The tertiary hospital group identified with the ‘medical model’ of birth, and the primary unit group identified with the ‘midwifery model’ of birth. Research evidence affirming the ‘clinical safety’ of primary units addresses only one aspect of the beliefs influencing women’s birthplace decision-making. In order for more women to give birth at a primary unit other aspects of women’s beliefs need addressing, and much wider socio-political change is required