3,759 research outputs found
Assessing quality in systematic reviews of the effectiveness of health promotion: areas of consensus and dissension
No full textSystematic reviews have played an increasingly important role in health promotion in recentyears. Yet there are debates about how they should be conducted, particularly about how thequality of evidence should be assessed. The aim of this research was to assess currentapproaches to, and general views on, the use of quality assessment in systematic reviews ofeffectiveness in health promotion, and to identify areas of consensus and dissension around thechoice of techniques, methods and criteria employed.There were two stages of data collection. The first was a structured mapping of a randomsample of 30 systematic reviews of the effectiveness of health promotion to identify and explaintrends and themes in methods and approaches to quality assessment. During the second stagesemi-structured interviews were conducted with a purposive sample of 17 systematic reviewerswho had conducted at least one review of a health promotion topic, to investigate some of thesetrends and approaches in greater detail.The mapping found that the majority of systematic reviews had assessed the quality of theincluded studies, to varying degrees. However, procedures were not always explicitly reportedor consistent. There was some degree of consensus over criteria, with experimental evaluationmethods commonly favoured. Most frequently used quality assessment criteria includedparticipant attrition, the validity and reliability of data collection and analysis methods, andadequacy of sample sizes. External validity was commonly assessed, primarily in terms ofgeneralisability and replicability, but less so in terms of intervention quality.The interviews revealed some of the barriers to effective systematic reviewing, including: lackof time and resources, complexity of some health promotion interventions, inclusion ofobservational evaluation designs, and poor reporting of primary studies. Systematic reviewingwas commonly done in small teams, mostly comprising academics, sometimes withpractitioners. Interviewees learned systematic review skills through a combination of training,support from colleagues and mentors, literature and a strong emphasis on hands-on practicallearning. Subjective judgement was often required, contra to the popular belief that systematicreviews are wholly objective.The overall conclusions of this study are that systematic reviewing in health promotion is oftenchallenging due the complexity of interventions and evaluation designs. This places additionaldemands on reviewers in terms of knowledge and skills required, often exacerbated by finitetime scales and limited funding. Initiatives are in place to foster shared ways of working,although the extent to which complete consensus is achievable in a multi- disciplinary area suchas health promotion is questionable
Pegylated and non-pegylated interferon-alfa and ribavirin for the treatment of mild chronic hepatitis C: A systematic review and meta-analysis
No full textObjectives: traditionally, patients with chronic hepatitis C virus (HCV) infection have not received treatment until their infection reaches the moderate to severe stage. The aim of this systematic review was to assess the clinical effectiveness of pegylated (PEG) and non-pegylated interferon (IFN) alfa and ribavirin (RBV) for the treatment of adults with histologically mild HCV.Methods: we performed a sensitive search of fourteen electronic bibliographic databases for literature that met criteria defined in a research protocol. Two reviewers independently selected studies, extracted data and assessed methodological quality.Results: ten randomized, controlled trials (RCTs) were included. Treatment with PEG + RBV combination therapy resulted in significantly higher sustained virological response (SVR) rates than treatment with IFN + RBV combination therapy. Treatment for 48 weeks with PEG + RBV was significantly more effective than the same treatment for 24 weeks. Significantly higher SVR rates were seen with IFN + RBV compared with either IFN monotherapy or no treatment. In the meta-analysis (four IFN trials), the relative risk of not experiencing an SVR was 0.59 (95 percent CI, 0.51 – 0.69) and was statistically significant (p < .00001). SVRs were higher for patients with genotype non-1 compared with genotype 1 for both PEG + RBV and IFN + RBV treatments.Conclusions: patients with histologically mild HCV can be successfully treated with both PEG and IFN combination therapy, and response rates are broadly comparable with those achieved in patients with advanced disease. Treating patients in the early milder stages of HCV is, therefore, a clinically effective option<br/
Thermocapillary approaches to the deliberate patterning of polymers
No full textThe phenomenon of thermocapillarity, the response of fluids to thermal gradients due to thermal alteration of their surface tension, was first reported over a century ago. Since then, research has focused generally on either the fundamentals or mitigation of this effect during the processing of materials. Only in the past two decades has the deliberate use of thermocapillary forces for the patterning of polymers been actively pursued, either for the ordering of internal structure or the introduction of topographic features. This review seeks to highlight this work and further identify directions for further investigation. In particular, while thermocapillary forces are often inextricably bound to other mechanisms, there are emerging directions in the deliberate coupling of forces to improve the capabilities of each mechanism. Further, the applications of thermocapillary patterning to polymer-nanoparticle composites has recently provided another promising route to active architectures.Peer reviewed
Ethnic identity, political identity and ethnic conflict: simulating the effect of congruence between the two identities on ethnic violence and conflict
No full textThis thesis outlines and presents an alternative hypothetical process to the emergence of ethnic conflict. Ethnic conflicts, rather than being dependent upon pre-existing 'ancient hatreds', are instead the result of a congruence between ethnic and political identity which grants individuals the ability to use ethnicity to identify and eliminate political threats. This hypothesis is formed by the examination of three case studies of ethnic conflict: Lebanon, Northern Ireland and Croatia. This hypothesis is then formalised and tested using an agent based simulation in which agent interactions are dependent upon ethnic and political identity and the congruence between the two. As predicted there was a strong positive correlation between how accurately ethnic identity reflected political identity and the level of ethnically motivated violence in the simulation, although the relationship was not linear. Furthermore the effect of a shift in congruence was found to be roughly comparable to the effect of initialising agents with a moderate level of pre-existing ethnic antagonism
Focused Laser-Induced Marangoni Dewetting for Patterning Polymer Thin Films
No full textHighly-localized focused laser spike (FLaSk) heating of polymer thin films is a resist- and developer-free alternative to 2D laser direct write for creating patterns on the single micron or, by exploiting overlap effects, submicron scale. The massive temporal and spatial thermal gradients and resulting thermal Marangoni stresses generated by FLaSk are an effective means for the directed dewetting and patterning of such films. Here, the general applicability of this technique to glassy amorphous polymer thin film systems is investigated through systematic investigation of film thickness, glass transition temperature, and polymer mobility. The results reveal that the important parameters are the film thickness (coupled to the optical heating effects through anti-reflection coating effects) and the high-temperature polymer melt mobility, allowing for generation of single features with linewidths of down to ~1 μm. Further, the introduction of spatial mobility variations by using polymer brushes, bilayers, and microphase separated block copolymers leads to additional profile manipulation effects (i.e. spontaneous 2D pattern generation and flattened top profiles).Peer reviewe
Adefovir dipivoxil and pegylated interferon alpha for the treatment of chronic hepatitis B: an updated systematic review and economic evaluation
No full textObjective:To update and extend a 2006 report on the clinical effectiveness and cost-effectiveness of adefovir dipivoxil (ADV) and pegylated interferon alpha (PEG-?) for the treatment of chronic hepatitis B (CHB).Data sources:Thirteen bibliographic databases were searched including MEDLINE, EMBASE and the Cochrane Library. Searches were run from the beginning of 2005 to September 2007.Review methods:For the clinical effectiveness review, randomised controlled trials (RCTs) comparing ADV, PEG-?-2a and PEG-?-2b with currently licensed treatments for CHB, including non-pegylated interferon alpha (IFN-?) and lamivudine (LAM), were included. Outcomes included biochemical, histological and virological response to treatment, drug resistance and adverse effects. A systematic review of economic evaluations of antiviral treatments for CHB was conducted. The economic Markov model used in the 2006 report was updated in terms of utility values, discount rates and costs.Results:Of the 82 papers retrieved for detailed screening, eight RCTs were included. Three evaluated ADV, four evaluated PEG-?-2b and one (from the original literature search) compared PEG-?-2b plus LAM with PEG-?-2b monotherapy. No RCTs of PEG-?-2a were identified. One ADV trial showed a statistically significant difference between ADV and placebo in terms of ALT response and HBV DNA levels, favouring ADV. Following withdrawal of ADV, levels were similar to those in placebo patients. In the ADV versus ADV plus LAM trial, there was a statistically significant difference in favour of the combination treatment. In the PEG-? trials, there were statistically significant differences favouring PEG-?-2b plus LAM compared with either one of the drugs given as monotherapy. For the comparison between PEG-?-2b and IFN-? and the comparison between different staggered regimens of the commencement of PEG-?-2b and LAM, there were no statistically significant differences between groups. Four full economic evaluations were identified, in addition to one identified in the original report. Two assessed PEG-?-2a; the remainder assessed ADV. PEG-?-2a was associated with increased treatment costs and gains in quality-adjusted life expectancy. In a UK study, the incremental cost-effectiveness ratio (ICER) for PEG-?-2a was £10,444 per QALY gained compared with LAM. Evaluations of ADV found that LAM monotherapy was dominated; the ICER for ADV monotherapy compared with 'doing nothing' was $19,731. The results of the updated analysis were generally robust to changes in deterministic sensitivity analysis. In a probabilistic sensitivity analysis, the same sequence of treatments was identified as optimal. In a probabilistic sensitivity analysis, PEG-?-2b had a probability of being cost-effective of 79% at a willingness-to-pay threshold of £20,000 per QALY, and 86% at a willingness-to-pay threshold of £30,000 per QALY.Conclusions:Both ADV and PEG-? are beneficial for patients with CHB in terms of suppressing viral load, reducing liver damage-associated biochemical activity, inducing HBeAg seroconversion, and reducing liver fibrosis and necroinflammation. The effects of long-term treatment with ADV are generally durable, with relatively low rates of resistance. In most cases, cost-effectiveness estimates were within acceptable ranges. Further research should assess the clinical effectiveness and cost-effectiveness of newer antiviral agents in relation to existing drugs, including the role of initiating treatment with combination therapy.<br/
On the Douglas-Rachford splitting method and the proximal point algorithm for maximal monotone operators
No full textCover title. "This paper consists mainly of dissertation research results of the first author."--Cover.Includes bibliographical references (p. 31-34).Research supported in part by the Army Research Office. DAAL03-86-K-0171 Research supported in part by the National Science Foundation. ECS-8519058by Jonathan Eckstein, Dimitri P. Bertsekas
Determination of critical cooling rates in metallic glass forming alloy libraries through laser spike annealing
No full textThe glass forming ability (GFA) of metallic glasses (MGs) is quantified by the critical cooling rate (RC). Despite its key role in MG research, experimental challenges have limited measured RC to a minute fraction of known glass formers. We present a combinatorial approach to directly measure RC for large compositional ranges. This is realized through the use of compositionally-graded alloy libraries, which were photo-thermally heated by scanning laser spike annealing of an absorbing layer, then melted and cooled at various rates. Coupled with X-ray diffraction mapping, GFA is determined from direct RC measurements. We exemplify this technique for the Au-Cu-Si system, where we identify Au56Cu27Si17 as the alloy with the highest GFA. In general, this method enables measurements of RC over large compositional areas, which is powerful for materials discovery and, when correlating with chemistry and other properties, for a deeper understanding of MG formation.Peer reviewe
Multiscale Patterning of a Metallic Glass using Sacrificial Imprint Lithography
No full textBulk metallic glasses have been advanced as a means to achieve durable multiscale, nanotextured surfaces with desirable properties dictated by topography for a multitude of applications. One barrier to this achievement is the lack of a bridging technique between macroscale thermoplastic forming and nanoimprint lithography, which arises from the difficulty and cost of generating controlled nanostructures on complex geometries using conventional top-down approaches. This difficulty is compounded by the necessary destruction of any resulting reentrant structures during rigid demolding. We have developed a generalized method to overcome this limitation by sacrificial template imprinting using zinc oxide nanostructures. It is established that such structures can be grown inexpensively and quickly with tunable morphologies on a wide variety of substrates out of solution, which we exploit to generate the nanoscale portion of the multiscale pattern through this bottom-up approach. In this way, we achieve metallic structures that simultaneously demonstrate features from the macroscale down to the nanoscale, requiring only the top-down fabrication of macro/microstructured molds. Upon detachment of the formed part from the multiscale molds, the zinc oxide remains embedded in the surface and can be removed by etching in mild conditions to both regenerate the mold and render the surface of the bulk metallic glass nanoporous. The ability to pattern metallic surfaces in a single step on length scales from centimeters down to nanometers is a critical step toward fabricating devices with complex shapes that rely on multiscale topography for their intended functions, such as for biomedical and electrochemical applications.Peer reviewe
Thermocapillary Multidewetting of Thin Films
No full textThermocapillary dewetting of liquids and molten films has recently emerged as a viable alternative to conventional microprocessing methods. As this thermal gradient-induced mechanism is universal, it can be applied to any material. This work explores the sequential dewetting of materials with varying melting points, including polymers and metals, to create aligned morphologies. The variation in melting point allows for the dewetting of single layers at a time or mobility-limited simultaneous dewetting. As a result, a variety of multimaterial structures can be produced with built-in alignment, such as arrays of concentric circles, lines with periodic segmentation, or islands on holes. This approach employs photothermal methods to induce the necessary thermal gradient, manipulating several variables in order to influence the consequent structures. Adjusting laser power and light intensity allows for the control of temperature for selective dewetting of films; altering beam size and exposure time affects the extent of dewetting in terms of diameter size; overlap effects and simultaneous dewetting can result in complex architectures. This controlled writing of patterns also presents a technique to create both masks at low temperatures for conductive multilayers as well as templates for electrospray deposition.Peer reviewe
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