Vibration control of pitch movement using command shaping techniques– Experimental investigation

This paper investigates the development of feedforward control strategies for vibration control of pitch movement (1 DOF) of a twin rotor multi-input multi-output system (TRMS) using command shaping techniques. Command shaping is a feedforward method used to reduce residual vibrations during motion in flexible systems. The TRMS is a laboratory platform designed for control experiments. In certain aspects, its behaviour resembles that of a helicopter. Feedforward controllers are designed for resonance suppression produced by the main rotor, which produces pitch movement around the longitudinal axis, while the lateral axis (yaw movement) is physically constrained. Three feed-forward controllers: input-shaper, low-pass filter and band-stop filter are designed based on the natural frequencies and damping ratios of the system. The three controllers are assessed in terms of level of vibration reduction at the system’s natural frequencies. Their performances are compared with an unshaped input (single-switch bang-bang signal) that is used to determine the dynamic response of the system

A mixed methods approach to evaluating community drug distributor performance in the control of neglected tropical diseases

BACKGROUND: Trusted literate, or semi-literate, community drug distributors (CDDs) are the primary implementers in integrated preventive chemotherapy (IPC) programmes for Neglected Tropical Disease (NTD) control. The CDDs are responsible for safely distributing drugs and for galvanising communities to repeatedly, often over many years, receive annual treatment, create and update treatment registers, monitor for side-effects and compile treatment coverage reports. These individuals are 'volunteers' for the programmes and do not receive remuneration for their annual work commitment. METHODS: A mixed methods approach, which included pictorial diaries to prospectively record CDD use of time, structured interviews and focus group discussions, was used to triangulate data on how 58 CDDs allocated their time towards their routine family activities and to NTD Programme activities in Uganda. The opportunity costs of CDD time were valued, performance assessed by determining the relationship between time and programme coverage, and CDD motivation for participating in the programme was explored. RESULTS: Key findings showed approximately 2.5 working weeks (range 0.6-11.4 working weeks) were spent on NTD Programme activities per year. The amount of time on NTD control activities significantly increased between the one and three deliveries that were required within an IPC campaign. CDD time spent on NTD Programme activities significantly reduced time available for subsistence and income generating engagements. As CDDs took more time to complete NTD Programme activities, their treatment performance, in terms of validated coverage, significantly decreased. Motivation for the programme was reported as low and CDDs felt undervalued. CONCLUSIONS: CDDs contribute a considerable amount of opportunity cost to the overall economic cost of the NTD Programme in Uganda due to the commitment of their time. Nevertheless, programme coverage of at least 75 %, as required by the World Health Organisation, is not being achieved and vulnerable individuals may not have access to treatment as a consequence of sub-optimal performance by the CDDs due to workload and programmatic factors

Use of Ex Vivo Normothermic Perfusion for Quality Assessment of Discarded Human Donor Pancreases.

A significant number of pancreases procured for transplantation are deemed unsuitable due to concerns about graft quality and the associated risk of complications. However, this decision is subjective and some declined grafts may be suitable for transplantation. Ex vivo normothermic perfusion (EVNP) prior to transplantation may allow a more objective assessment of graft quality and reduce discard rates. We report ex vivo normothermic perfusion of human pancreases procured but declined for transplantation, with ABO-compatible warm oxygenated packed red blood cells for 1-2 h. Five declined human pancreases were assessed using this technique after a median cold ischemia time of 13 h 19 min. One pancreas, with cold ischemia over 30 h, did not appear viable and was excluded. In the remaining pancreases, blood flow and pH were maintained throughout perfusion. Insulin secretion was observed in all four pancreases, but was lowest in an older donation after cardiac death pancreas. Amylase levels were highest in a gland with significant fat infiltration. This is the first study to assess the perfusion, injury, as measured by amylase, and exocrine function of human pancreases using EVNP and demonstrates the feasibility of the approach, although further refinements are required.This study was financially supported by a grant from the Mason Medical Research Foundation.This is the author accepted manuscript. The final version is available via Wiley at http://onlinelibrary.wiley.com/doi/10.1111/ajt.13303/abstract

Evolutionary connectionism: algorithmic principles underlying the evolution of biological organisation in evo-devo, evo-eco and evolutionary transitions

The mechanisms of variation, selection and inheritance, on which evolution by natural selection depends, are not fixed over evolutionary time. Current evolutionary biology is increasingly focussed on understanding how the evolution of developmental organisations modifies the distribution of phenotypic variation, the evolution of ecological relationships modifies the selective environment, and the evolution of reproductive relationships modifies the heritability of the evolutionary unit. The major transitions in evolution, in particular, involve radical changes in developmental, ecological and reproductive organisations that instantiate variation, selection and inheritance at a higher level of biological organisation. However, current evolutionary theory is poorly equipped to describe how these organisations change over evolutionary time and especially how that results in adaptive complexes at successive scales of organisation (the key problem is that evolution is self-referential, i.e. the products of evolution change the parameters of the evolutionary process). Here we first reinterpret the central open questions in these domains from a perspective that emphasises the common underlying themes. We then synthesise the findings from a developing body of work that is building a new theoretical approach to these questions by converting well-understood theory and results from models of cognitive learning. Specifically, connectionist models of memory and learning demonstrate how simple incremental mechanisms, adjusting the relationships between individually-simple components, can produce organisations that exhibit complex system-level behaviours and improve the adaptive capabilities of the system. We use the term “evolutionary connectionism” to recognise that, by functionally equivalent processes, natural selection acting on the relationships within and between evolutionary entities can result in organisations that produce complex system-level behaviours in evolutionary systems and modify the adaptive capabilities of natural selection over time. We review the evidence supporting the functional equivalences between the domains of learning and of evolution, and discuss the potential for this to resolve conceptual problems in our understanding of the evolution of developmental, ecological and reproductive organisations and, in particular, the major evolutionary transitions

Hysteroscopic Endometrial Resection in the Management of Abnormal Uterine Bleeding Among Libyan Women

Background: Abnormal uterine bleeding (AUB) is a major health problem and it is a substantial cause of ill health in women. Medical treatment has a high failure rate and adverse effects. There are few published data on hysteroscopic endometrial resection (HER) in the management of patients with AUB.Objective: To investigate the efficacy and outcomes of hysteroscopic endometrial resection (HER) in patients with AUB.Materials and Methods: A descriptive hospital - based study was carried out at the departments of Obstetrics and Gynecology, Misurata and Sirt, Libya, during the period from January 2009 to December 2013. Women with AUB were recruited in the study. All women had a detailed medical and obstetrical history, physical examination and the hysteroscopic endometrial ablation and were followed-up for success or failure of the procedure which was assessed via symptoms (bleeding).Results: A total of 120 women with mean (SD) of age and parity of 42.3 (6.8) years and 3.8 (2.4), respectively were recruited in the study initially. Thirty (25%) of these women were lost of followup Therefore, only 70 women (50 with DUB, and 20 women with fibroids) were available for the final analysis. All women underwent hysteroscopic endometrial resection and 28 of them had hysteroscopic myomectomy. The success rate was 92.8% (65/70) after 2 years follow up. All the five women with failure of the procedure were younger (<40 years); had bleeding with dysmenorrhea, bigger uterine size, thicker endometrium (> 7 mm) and they had fibroids.Conclusions: Endometrial resection is an effective procedure in the majority of women with AUB, especially in those over age of 40 and without an increase in uterine size and has no fibroids.Keywords: Uterine bleeding, hysteroscopic, endometrial resection, Libya

Hysteroscopy in Libyan women with Recurrent Pregnancy Loss

Background: Hysteroscopy is an efficient procedure of management in many gynecologic conditions. There are few published data on hysteroscopy and recurrent pregnancy loss especially in developing countries.Objectives: To assess hysteroscopic findings in patients with consecutive miscarriages, and to compare the prevalence of uterine abnormalities between women with two and three or more miscarriages.Methods: Three hundred and twenty four women with two or more consecutive miscarriages were enrolled in the study. All participants underwent a diagnostic hysteroscopy. Congenital (arcuate uterus, septate uterus, unicornuate uterus) and acquired uterine abnormalities (intrauterine adhesions, polyp and submucous myoma) were documented. The findings were compared between the groups of women with two miscarriages and women who had three or more miscarriages.Results: Out of a total of 324 women [their mean (SD) of the age and gravidity was 28.3 (6.5) years and 5.1(1.5), respectively] 135 (41.7%) and 189 (58.3%) had two consecutive miscarriages and three or more consecutive miscarriages, respectively. While 194 (59.9%) women had no pathological findings on hysteroscopy, 130 (40.1%) women were found to have uterine anomalies. The congenital anomalies were found in 79 (24.4%) and the acquired were in 51 (15.7%) women. In comparison with women who had three or more miscarriages, women who had two miscarriages had significantly higher number of congenital anomalies, 53/135 (39.2%) vs. 26/189 (13.8%), P < 0.001. However there was no significant difference in the acquired anomalies between women who had two miscarriages and women who had three or more miscarriages.Conclusions: Patients who had two consecutive miscarriages were found to have a higher prevalence of congenital anatomical abnormalities. Diagnostic hysteroscopy should be carried out after two such miscarriages.Keywords: Hysteroscope, Recurrent Pregnancy Loss, miscarriage, Libya

Magnetism, FeS colloids, and Origins of Life

A number of features of living systems: reversible interactions and weak bonds underlying motor-dynamics; gel-sol transitions; cellular connected fractal organization; asymmetry in interactions and organization; quantum coherent phenomena; to name some, can have a natural accounting via $physical$ interactions, which we therefore seek to incorporate by expanding the horizons of `chemistry-only' approaches to the origins of life. It is suggested that the magnetic 'face' of the minerals from the inorganic world, recognized to have played a pivotal role in initiating Life, may throw light on some of these issues. A magnetic environment in the form of rocks in the Hadean Ocean could have enabled the accretion and therefore an ordered confinement of super-paramagnetic colloids within a structured phase. A moderate H-field can help magnetic nano-particles to not only overcome thermal fluctuations but also harness them. Such controlled dynamics brings in the possibility of accessing quantum effects, which together with frustrations in magnetic ordering and hysteresis (a natural mechanism for a primitive memory) could throw light on the birth of biological information which, as Abel argues, requires a combination of order and complexity. This scenario gains strength from observations of scale-free framboidal forms of the greigite mineral, with a magnetic basis of assembly. And greigite's metabolic potential plays a key role in the mound scenario of Russell and coworkers-an expansion of which is suggested for including magnetism.Comment: 42 pages, 5 figures, to be published in A.R. Memorial volume, Ed Krishnaswami Alladi, Springer 201

Genetic algorithm optimization and control system design of flexible structures

This paper presents an investigation into the deployment of genetic algorithm (GA)-based controller design and optimization for vibration suppression in flexible structures. The potential of GA is explored in three case studies. In the first case study, the potential of GA is demonstrated in the development and optimization of a hybrid learning control scheme for vibration control of flexible manipulators. In the second case study, an active control mechanism for vibration suppression of flexible beam structures using GA optimization technique is proposed. The third case study presents the development of an effective adaptive command shaping control scheme for vibration control of a twin rotor system, where GA is employed to optimize the amplitudes and time locations of the impulses in the proposed control algorithm. The effectiveness of the proposed control schemes is verified in both an experimental and a simulation environment, and their performances are assessed in both the time and frequency domains

Vortices in polariton OPO superfluids

This chapter reviews the occurrence of quantised vortices in polariton fluids, primarily when polaritons are driven in the optical parametric oscillator (OPO) regime. We first review the OPO physics, together with both its analytical and numerical modelling, the latter being necessary for the description of finite size systems. Pattern formation is typical in systems driven away from equilibrium. Similarly, we find that uniform OPO solutions can be unstable to the spontaneous formation of quantised vortices. However, metastable vortices can only be injected externally into an otherwise stable symmetric state, and their persistence is due to the OPO superfluid properties. We discuss how the currents charactering an OPO play a crucial role in the occurrence and dynamics of both metastable and spontaneous vortices.Comment: 40 pages, 16 figure