Maximal induced matchings in triangle-free graphs

An induced matching in a graph is a set of edges whose endpoints induce a $1$-regular subgraph. It is known that any $n$-vertex graph has at most $10^{n/5} \approx 1.5849^n$ maximal induced matchings, and this bound is best possible. We prove that any $n$-vertex triangle-free graph has at most $3^{n/3} \approx 1.4423^n$ maximal induced matchings, and this bound is attained by any disjoint union of copies of the complete bipartite graph $K_{3,3}$. Our result implies that all maximal induced matchings in an $n$-vertex triangle-free graph can be listed in time $O(1.4423^n)$, yielding the fastest known algorithm for finding a maximum induced matching in a triangle-free graph.Comment: 17 page

An Improved Exact Algorithm for the Exact Satisfiability Problem

The Exact Satisfiability problem, XSAT, is defined as the problem of finding a satisfying assignment to a formula $\varphi$ in CNF such that exactly one literal in each clause is assigned to be "1" and the other literals in the same clause are set to "0". Since it is an important variant of the satisfiability problem, XSAT has also been studied heavily and has seen numerous improvements to the development of its exact algorithms over the years. The fastest known exact algorithm to solve XSAT runs in $O(1.1730^n)$ time, where $n$ is the number of variables in the formula. In this paper, we propose a faster exact algorithm that solves the problem in $O(1.1674^n)$ time. Like many of the authors working on this problem, we give a DPLL algorithm to solve it. The novelty of this paper lies on the design of the nonstandard measure, to help us to tighten the analysis of the algorithm further

Supply-related drivers of staff motivation for providing intermittent preventive treatment of malaria during pregnancy in Tanzania: evidence from two rural districts

BACKGROUND: Since its introduction in the national antenatal care (ANC) system in Tanzania in 2001, little evidence is documented regarding the motivation and performance of health workers (HWs) in the provision of intermittent preventive treatment of malaria during pregnancy (IPTp) services in the national ANC clinics and the implications such motivation and performance might have had on HWs and services' compliance with the recommended IPTp delivery guidelines. This paper describes the supply-related drivers of motivation and performance of HWs in administering IPTp doses among other ANC services delivered in public and private health facilities (HFs) in Tanzania, using a case study of Mkuranga and Mufindi districts. METHODS: Interviews were conducted with 78 HWs participating in the delivery of ANC services in private and public HFs and were supplemented by personal communications with the members of the district council health management team. The research instrument used in the data collection process contained a mixture of closed and open-ended questions. Some of the open-ended questions had to be coded in the form that allowed their analysis quantitatively. RESULTS: In both districts, respondents acknowledged IPTp as an essential intervention, but expressed dissatisfaction with their working environments constraining their performance, including health facility (HF) unit understaffing; unsystematic and unfriendly supervision by CHMT members; limited opportunities for HW career development; and poor (HF) infrastructure and staff houses. Data also suggest that poor working conditions negatively affect health workers' motivation to perform for ANC (including IPTp) services. Similarities and differences were noted in terms of motivational factors for ANC service delivery between the HWs employed in private HFs and those in public HFs: those in private facilities were more comfortable with staff residential houses, HF buildings, equipment, availability of water, electricity and cups for clients to use while taking doses under direct observed therapy than their public facility counterparts. Employees in public HFs more acknowledged availability of clinical officers, nurses and midwives than their private facility counterparts. More results are presented and discussed. CONCLUSION: The study shows conditions related to staffing levels, health infrastructure and essential supplies being among the key determinants or drivers of frontline HWs' motivation to deliver ANC services in both private and public HFs. Efforts of the government to meet the maternal health related Millennium Development Goals and targets for specific interventions need to address challenges related to HWs' motivation to perform their duties at their work-places

National health policy-makers’ views on the clarity and utility of Countdown to 2015 country profiles and reports: findings from two exploratory qualitative studies

Background: The use of sets of indicators to assess progress has become commonplace in the global health arena. Exploratory research has suggested that indicators used for global monitoring purposes can play a role in national policy-making, however, the mechanisms through which this occurs are poorly understood. This article reports findings from two qualitative studies that aimed to explore national policy-makers’ interpretation and use of indicators from country profiles and reports developed by Countdown to 2015. Methods: An initial study aimed at exploring comprehension of Countdown data was conducted at the 2010 joint Women Deliver/Countdown conference. A second study was conducted at the 64th World Health Assembly in 2011, specifically targeting national policy-makers. Semi-structured interviews were carried out with 29 and 22 participants, respectively, at each event. Participants were asked about their understanding of specific graphs and indicators used or proposed for use in Countdown country profiles, and their perception of how such data can inform national policy-making. Responses were categorised using a framework analysis. Results: Respondents in both studies acknowledged the importance of the profiles for tracking progress on key health indicators in and across countries, noting that they could be used to highlight changes in coverage, possible directions for future policy, for lobbying finance ministers to increase resources for health, and to stimulate competition between neighbouring or socioeconomically similar countries. However, some respondents raised questions about discrepancies between global estimates and data produced by national governments, and some struggled to understand the profile graphs shown in the absence of explanatory text. Some respondents reported that use of Countdown data in national policy-making was constrained by limited awareness of the initiative, insufficient detail in the country profiles to inform policy, and the absence of indicators felt to be more appropriate to their own country contexts. Conclusions: The two studies emphasise the need for country consultations to ensure that national policy-makers understand how to interpret and use tools like the Countdown profile for planning purposes. They make clear the value of qualitative research for refining tools used to promote accountability, and the need for country level Countdown-like processes

Action to protect the independence and integrity of global health research

Storeng KT, Abimbola S, Balabanova D, et al. Action to protect the independence and integrity of global health research. BMJ GLOBAL HEALTH. 2019;4(3): e001746

Ultrashort laser pulse ablation of copper, silicon and gelatin: effect of the pulse duration on the ablation thresholds and the incubation coefficients

The final publication is available at Springer via https://doi.org/10.1007/s00339-016-9625-6.In this paper, the influence of the pulse duration on the ablation threshold and the incubation coefficient was investigated for three different types of materials: metal (copper), semiconductor (silicon) and biopolymer (gelatin). Ablation threshold values and the incubation coefficients have been measured for multiple Ti:sapphire laser pulses (3 to 1000 pulses) and for four different pulse durations (10, 30, 250 and 550 fs). The ablation threshold fluence was determined by extrapolation of curves from squared crater diameter versus fluence plots. For copper and silicon, the experiments were conducted in vacuum and for gelatin in air. For all materials, the ablation threshold fluence increases with the pulse duration. For copper, the threshold increases as τ 0.05, for silicon as τ 0.12 and for gelatin as τ 0.22. By extrapolating the curves of the threshold fluence versus number of pulses, the single-shot threshold fluence was determined for each sample. For 30 fs pulses, the single-shot threshold fluences were found to be 0.79, 0.35, and 0.99 J/cm2 and the incubation coefficients were found to be 0.75, 0.83 and 0.68 for copper, silicon and gelatin, respectively.Austrian Research Promotion Agency (FFG