Input-output oriented computation algorithms for the control of large flexible structures

An overview is given of work in progress aimed at developing computational algorithms addressing two important aspects in the control of large flexible space structures; namely, the selection and placement of sensors and actuators, and the resulting multivariable control law design problem. The issue of sensor/actuator set selection is particularly crucial to obtaining a satisfactory control design, as clearly a poor choice will inherently limit the degree to which good control can be achieved. With regard to control law design, the researchers are driven by concerns stemming from the practical issues associated with eventual implementation of multivariable control laws, such as reliability, limit protection, multimode operation, sampling rate selection, processor throughput, etc. Naturally, the burden imposed by dealing with these aspects of the problem can be reduced by ensuring that the complexity of the compensator is minimized. Our approach to these problems is based on extensions to input/output oriented techniques that have proven useful in the design of multivariable control systems for aircraft engines. In particular, researchers are exploring the use of relative gain analysis and the condition number as a means of quantifying the process of sensor/actuator selection and placement for shape control of a large space platform

Automated high accuracy, rapid beam hardening correction in X-Ray Computed Tomography of multi-mineral, heterogeneous core samples

X-ray Computed Tomography scanning is an innovative procedure that allows representing the internal structure of samples. Among its several purposes, X-ray CT is widely used for investigation of petrophysical properties of porous media. To provide accurate results, it is necessary to have high quality scan images, free of artefacts. One of the most problematic artefacts is beam hardening, which, in cylindrical shapes, increases the attenuation values with increasing distance from the centre. Until now, no automatic solution has been proposed for cylindrically-shaped cores that is both computationally feasible and applicable to all geological media. A new technique is here introduced for correcting beam hardening, using a linearization procedure of the beam hardening curve applied after the reconstruction process. We have developed an automated open source plug-in, running on ImageJ software, which does not require any a priori knowledge of the material, distance from the source or the scan conditions (current, energy), nor any segmentation of phases or calibration scan on phantom data. It is suitable for expert and non-expert use, alike. We have tested the technique on μCT scan images of a plastic rod, a sample of loose sand, several heterogeneous sandstone core samples (with near-cylindrical shapes), and finally, on an internal scan of a Berea sandstone core. The Berea core was also scanned using a medical X-ray CT scanner with a fan-beam geometry, as opposed to a cone beam geometry, showing that our algorithm is equally effective in both cases. Our correction technique successfully removes the beam hardening artefact in all cases, as well as removing the cupping effect common to internal scans. For a Berea Sandstone, with a porosity of 20%, porosity calculated using the corrected scan is 20.54%, which compares to a value of 14.24% using the software provided by the manufacturer

Predator decline leads to decreased stability in a coastal fish community

Fisheries exploitation has caused widespread declines in marine predators. Theory predicts that predator depletion will destabilise lower trophic levels, making natural communities more vulnerable to environmental perturbations. However, empirical evidence has been limited. Using a community matrix model, we empirically assessed trends in the stability of a multispecies coastal fish community over the course of predator depletion. Three indices of community stability (resistance, resilience and reactivity) revealed significantly decreasing stability concurrent with declining predator abundance. The trophically downgraded community exhibited weaker top-down control, leading to predator-release processes in lower trophic levels and increased susceptibility to perturbation. At the community level, our results suggest that high predator abundance acts as a stabilising force to the naturally stochastic and highly autocorrelated dynamics in low trophic species. These findings have important implications for the conservation and management of predators in marine ecosystems and provide empirical support for the theory of predatory control

Antibodies against 9-O-acetylated sialoglycans: a potent marker to monitor clinical status in childhood acute lymphoblastic leukemia

Background: Although childhood acute lymphoblastic leukemia (ALL) is highly responsive to chemotherapy, reliable techniques are needed to determine treatment outcome and predict impending relapse. In ALL, the cell surface over expression of 9-O-acetylated sialoglycans (9-OAcSGs) on lymphoblasts and concomitant high antibody titers in patients' sera was reported. Objectives: The present study was aimed to evaluate whether anti-9-OAcSG titers can be harnessed to monitor the clinical outcome of ALL. Design and methods: Anti-9-OAcSGs were analyzed by ELISA in children receiving either UK ALL X (n = 69, Group I) in India or UK ALL 97 (n = 47, Group II) in UK along with age-matched normal healthy controls at different time points over a period of > 2 years. An attempt was also made to investigate subclass distribution of disease-specific IgG. Moreover, 17 patients having a higher sample size were longitudinally monitored. Results: Antibody levels were raised at disease presentation, decreased with remission induction, and importantly, reappeared with clinical relapse. Sera from patients with other hematological disorders and normal controls showed negligible levels of circulating anti-9-OAcSGs. In patients of both Groups I and II, the assay showed high sensitivity (98.92% and 96.77%) and specificity (92.1% and 95.91%), respectively. IgG subclass analyses during different phases of treatment revealed that 9-OAcSG-specific IgG1 could serve as a better prognostic marker in ALL. Conclusions: This study demonstrated the potential of this disease-specific antibody as an alternate marker in diagnosis and long-term assessment of ALL patients, suggesting its application in detection and prediction of impending relapse. Therefore, the expression of anti-9-OAcSGs, irrespective of their treatment protocol, may serve as an economical yet effective index for monitoring of childhood ALL

Study of relationship between age and body mass index on knee osteoarthritis in advanced aged females in a divisional city of Bangladesh

Background: Knee osteoarthritis is a notable issue in senior citizens and is a burning problem worldwide. There are so many risk factors related to knee osteoarthritis but women's sex, age, and obesity are significant. The aim and objective of this study were to estimate the prevalence of knee osteoarthritis among women in the age group of 46 to 65 years and the effect of age and body mass index (BMI) on knee osteoarthritis.Methods: Cross-sectional study was conducted at outpatient department (OPD) in Mymensingh Medical College Hospital, a tertiary level hospital, among females of Mymensingh, a divisional city of Bangladesh in the age group of 46 to 65 years. Purposive sampling technique used to select study subjects. A total of 100 females participated in this study in one month (July 2019-August 2019).Results: 100 participants were enlisted in the study, in the age group of 46 to 55 years 39 (39%) and 56 to 65 years 61 (61%). Total 65 (65%) participants were affected with knee osteoarthritis. Among them, 19 (29.2%) participants were in the age group of 46-55 years and 46 (70.8%) participants were in the age group of 55-65 years, thus in the advanced age group, knee osteoarthritis is remarkably more. Participants affected with knee osteoarthritis with BMI ≥25 were significantly more affected 45 (69.2%) compared with participants with normal BMI 20 (30.2%).Conclusions: Knee osteoarthritis is significantly associated with advanced age and obesity. Advanced age and overweight were strongly associated with osteoarthritis in our population. Therefore, weight reduction and preventive measures can decrease the burden and will help in minimizing morbidity associated with OA

ANALISA RISIKO PENCEMARAN LINGKUNGAN AKIBAT OPERASIONAL KAPAL DI PELABUHAN TANJUNG PERAK SURABAYA

Meningkatnnya aktivitas pelayaran di Pelabuhan Tanjung Perak Surabaya akan menyebabkan tingkat risiko pencemaran lingkungan ( laut, darat dan udara). Tujuan utama penelitian ini adalah pencemaran udara pada operasional kapal di pelabuhan Tanjung Perak Surabaya dan sistem pencemaran udara yang sudah diatur oleh MARPOL. Metode yang digunakan dalam penelitian ini khususnya dalam menganalisis data menggunakan metode regrasi yang sudah diteliti oleh trozzi. Hasil yang di peroleh dalam penelitian ini adalah bahwa pada polutan Nox hasil terbanyak dalam waktu 3 hari yaitu polutan yang dikeluarkan pada hari pertama dengan jumlah Total Emisi Nox 2987,584534 Kg, Total Emisi CO 12859,60299 Kg, Total Emisi CO2 415663,9352 Kg, Total Emisi VOC 3000,574032 Kg, Total Emisi PM 155,8739757 Kg, Total Emisi Sox 2597,899595 Kg. emisi gas buang yang dikeluarkan rata- rata di atas ambang batas. Dimana batas kualitas udara yang tergolong untuk dikatakan berpotensi pencemaran adalah 12,51 sedangkan hasil perhitungan yang didapat yaitu dengan jumlah 61,09055556 begitupun dengan hasil yang lainnya

Guide to Best Practice in Seascape Assessment

Seascape is a crucial element in any maritime nation’s sense of identity and culture. It has played an important part in the history and development of Ireland and Wales. The coast and the sea is a primary holiday and leisure location and is a significant asset in a nation’s recreational resource. The coast and related seascape is a finite resource under almost continual pressure for development. In both Ireland and Wales we are currently experiencing a period of exceptional change around our coasts. The response to sea level rise is generating more proposals for coastal defence works. We have seen the development of new ports and the upgrading of existing facilities, and proposals for aquaculture schemes have become more prevalent around some coasts. Energy strategies are giving rise to wind turbine projects off both coasts. We have also become more aware of how valuable and important our seascapes are to the character and identity of much of our countryside, towns and cities. With all of these development pressures related to the coast and the sea, a systematic approach to issues raised is now timely and essential to ensure that the decision making process has the tools to deal with the upcoming changes. For these reasons development that affects our coasts and seascapes require particular attention and care. Such consideration can best be given in a structure based upon a thorough understanding of the character and values attributable to the relevant seascapes. This guide attempts to provide a methodology to deal with the issues involved.Funder: European Unio

Comparative studies on the structure of an upland African stream ecosystem

Upland stream systems have been extensively investigated in Europe, North America and Australasia and many of the central ideas concerning their function are based on these systems. One central paradigm, the river continuum concept is ultimately derived from those North American streams whose catchments remain forested with native vegetation. Streams of the tropics may or may not fit the model. They have been little studied. The Amani Nature Reserve in the East Usambara Mountains of north-eastern Tanzania offers an opportunity to bring these naturally forested systems to the attention of the ecological community. This article describes a comparison made between two lengths of the River Dodwe in this area. The work was carried out by a group of postgraduate students from eighteen European and African countries with advice from five staff members, as part of a course organised by the Tropical Biology Association. Rigorous efforts were made to standardise techniques, in a situation where equipment and laboratory facilities were very basic, through a management structure and deliberate allocation of work to specialists in each area.The article offers a summary of invertebrate communities found in the stream and its biomass. Crabs seem to be the key organism in both sections of the streams

A conserved amino acid residue critical for product and substrate specificity in plant triterpene synthases

Triterpenes are structurally complex plant natural products with numerous medicinal applications. They are synthesized through an origami-like process that involves cyclization of the linear 30 carbon precursor 2,3-oxidosqualene into different triterpene scaffolds. Here, through a forward genetic screen in planta, we identify a conserved amino acid residue that determines product specificity in triterpene synthases from diverse plant species. Mutation of this residue results in a major change in triterpene cyclization, with production of tetracyclic rather than pentacyclic products. The mutated enzymes also use the more highly oxygenated substrate dioxidosqualene in preference to 2,3-oxidosqualene when expressed in yeast. Our discoveries provide new insights into triterpene cyclization, revealing hidden functional diversity within triterpene synthases. They further open up opportunities to engineer novel oxygenated triterpene scaffolds by manipulating the precursor supply

Operationalizing ensemble models for scientific advice to fisheries management

This paper explores the possibility of using the ensemble modelling paradigm to fully capture assessment uncertainty and improve the robustness of advice provision. We identify and discuss advantages and challenges of ensemble modelling approaches in the context of scientific advice. There are uncertainties associated with every phase in the stock assessment process: data collection, assessment model choice, model assumptions, interpretation of risk, up to the implementation of management advice. Additionally, the dynamics of fish populations are complex, and our incomplete understanding of those dynamics and limited observations of important mechanisms, necessitate that models are simpler than nature. The aim is for the model to capture enough of the dynamics to accurately estimate trends and abundance, and provide the basis for robust advice about sustainable harvests. The status quo approach to assessment modelling has been to identify the “best” model and generate advice from that model, mostly ignoring advice from other model configurations regardless of how closely they performed relative to the chosen model. We discuss and make suggestions about the utility of ensemble models, including revisions to the formal process of providing advice to management bodies, and recommend further research to evaluate potential gains in modelling and advice performance.publishedVersio