138,014 research outputs found
When experimental practice comes first
No full textThis article hosts a vivid discussion on Papadopoulos’ book Experimental Practice. Technoscience, Alterontologies and More-Than-Social Movements (Duke University Press, 2018). This is a speculative and politically engaged book. It crosses the boundaries of social theory, science and technology studies, feminist theory and autonomist thought. The following contributions explore and critically discuss an essential topic of the book: the role of movements and everyday practices in transforming eco-societies from below. Andrea Ghelfi situates the book in an historical contingency in which social transformation is primarily driven by material, ontological transformation. Luigi Pellizzoni offers an analysis of the ambivalences of experimentalism in a context marked by neoliberal governmentality. Roberta Raffaetà brings attention to three interrelated themes: practice, theory and the role of institutional power. Finally, Dimitris Papadopoulos’ response focuses on the complicate relation between practice and politics in more-than-social movements
At the computer's edge. The value of virtual constructions to the interpretation of cultural heritage
No full textThe title of this paper is an adaptation of Ian Hodder’s notion that interpretation starts ‘at the trowel’s edge’ (1997), as excavations should be active, reflexive and multivocal practices, during which interpretation takes place as an inextricable part of our research. The process of interpretation is a complicated issue. It has engrossed most practitioners, and is closely related to the conceptualisation of the past as reflecting contemporary social and cultural experiences through the scrutiny of cultural heritage remains. Archaeological remains are under appreciated, as they can be accessed only by specialised audiences, and any finds are presented by means of conventional illustrations and comprehensive list of artefacts. Even the most common recording method in archaeology, i.e. fieldnotes, and the subsequent site reports, have been criticised (Hodder 1989) for their distance and impersonality, as well as their attempt to demonstrate objectivity by establishing rigorous classifications and complex terminologies. For that reason, different forms of media have been used in the interpretive processes, not only in scientific research, but also for providing varied levels of engagement with the archaeological datasets by the public
Compte rendu de Anagnostopoulou (D.), Papadopoulos (I.), Papadopoulou (L.). The EU at a Crossroads. Challenges and Perspectives
No full textAnagnostopoulou (D.), Papadopoulos (I.), Papadopoulou (L.). – The EU at a Crossroads. Challenges and Perspectives. – Cambridge: Cambridge Scholars publishing, 2016. – 310 p. – ISBN: 9781443899291
Feather meal : evaluation of the effect of processing conditions by chemical and chick assays
No full textFeather waste at poultry processing plants, has been of interest in nutritional studies because of its high protein content. This material must be hydrolyzed in order to be digested by the animal, because in its natural state it is of no nutritive value. However, this product will be of variable quality because hydrolysis has not only beneficial effects but can also reduce the nutritive value in terms of amino acid content and digestibility. Although feather meal is used in poultry feeding, our present knowledge of its protein-amino acid quality is inadequate. The value of feather meal as a component of animal feeds could be better assessed if more were known about the effect of different processing conditions on the content and digestibility of its amino acids. Therefore, the investigation described in this thesis was conducted in order to study chemical, nutritional and physiological aspects of feather meal treated under different conditions.The first major part of this study was an evaluation of feather meal proteinamino acid quality by chemical methods (Chapter 2). Crude protein analysis and digestibility determinations in vitro are often used in practice as a rapid quality-control method. The amino acid composition in relation to the amino acid requirements of the animal is also taken into account in formulating rations.The effects of five processing times (30, 40, 50, 60 and 70 min), five moisture contents (50, 55, 60, 65 and 70%), five added levels of sodium hydroxide (0.2, 0.3, 0.4, 0.5 and 0.6%) and proteolytic enzyme (0.2, 0.3, 0.4, 0.5 and 0.6%) upon amino acid concentration and nitrogen solubility of feather meal were studied by multiple regression techniques in three experiments (section 2.3.2). The first experiment examined the combinations of time and moisture. The second and third experiments contained the combinations of time, moisture, sodium hydroxide and of time, moisture, enzyme respectively. All test products were autoclaved at a constant temperature of 146°C.The results of these experiments showed that the individual amino acids have distinct variations in their response to various processing variables (time, moisture, sodium hydroxide, enzyme). There are losses, in qeneral, of amino acids during the processing of feather meal. These losses were more pronounced in the chemically treated feather meals, followed by the enzymatically treated ones compared with feather meals treated without additions. In the last treatments some amino acids, valine, leucine, tyrosine and phenylalanine, proved to be rather stable during processing. The protein solubility of the testfeather meals in pepsin-HCl solution and alkali or acid solvents was increased as a result of processing. However, the amino acid contents and especially that of cystine were decreased. This suggests that the amount of cystine may be a reliable index of the degree of processing since feather meals with lower cystine content showed higher protein solubility/digestibility values.The reduction of amino acids can be explained by changes in the protein structure as a result of protein cross-linking reactions and the formation of new amino acids (section 2.5.3). Evidence of the nature of these chemical changes is given in section 2.4.5 in which the formation of the unnatural amino acid lanthionine concurrent with the drastic destruction of cystine is described.Summarizing the above, it can be concluded that:a) there is, in general, a negative processing effect on amino acid contents and a positive one on nitrogen solubility;b) amino acids and nitrogen solubility/digestibility, estimated by chemical methods, have very clear variations in their response to different process variables, leading to the conclusion that it is difficult to find an adequate criterion of optimal processing conditions;c) there is an inverse relationship between amino acid contents and nitrogen solubility/digestibility, suggesting that, in this stage, it is difficult to evaluate the effect of processing on feather meal protein as a whole from the corresponding effects on the amino acid contents and nitrogen solubility.The losses of amino acids as demonstrated in Chapter 2 may not be of much nutritional significance unless other structural modifications to the protein affect in vivo digestibility of crude protein and amino acids. There is a need for a bioassay of the protein because physico- chemical analyses have a limited value in that they give little or no indication of individual amino acid availability for digestion, absorption and metabolism by the animal. Therefore, a second major objective of this study was the use of biological methods for estimating the value of the differently processed feather meals (Chapter 3). In this chapter the effect of three processing times (30, 50 and 70 min) and three methods of treatments (without additions, added sodium hydroxide 0.4% and added enzyme 0.4%) were investigated. The digestibility of the test feather meal protein/amino acids was determined by quantitative excreta collection over a period of 36 hrs. All the test chicks were force- fed with 12 9 of feather meal (dry matter) given in 2 doses with a 3 hr interval between feeds. Correction was made for metabolic plus endogenous excretions by using a nitrogenfree diet to distinguish apparent from true digestibility.The apparent and true digestibility of all individual amino acids were influenced by the processing conditions. The main significant effect was the processing time. There was a negative time-linear effect on the digestibility of all amino acids of the feather meals, with the exception of leucine. Significant differences in digestibility coefficients due to the method of treatment were found for some amino acids, cystine, tyrosine, phenylalanine, serine and alanine. Their values were lower in the chemically treated feather meals. Comparison between the three methods of feather meal treatment revealed higher values for the enzymatically treated samples and lower values for the chemically treated ones, compared with samples treated without additions.An interesting feature of this experiment was the considerable variation between individual amino acids in their digestibility values. They ranged in apparent digestibility values from 22.5% for lysine to 82.4% for isoleucine and, in true digestibility values, from 36.3% for aspartic acid to 86.5% for isoleucine. The three limiting essential amino acids lysine, histidine and methionine, in increasing order, were particularly low in digestibility.The reduction in amino acid digestibility can be explained by the fact that autoclaving feather meal may have altered the protein structure in such a way that the enzymic attack, necessarily associated with the digestion process, is hindered. It has been suggested that heat/alkali causes the formation of new cross-linkages within the protein molecules and this leads to the formation of new amino acids (section 2.5.3), as in the case of lanthionine in our experiments. Cross-linkage formation reduces the rate of protein digestion possibly by preventing enzyme penetration or by blocking the sites of enzyme attack (section 3.5.3). Our results showed that feather meals with higher lanthionine content had lower amino acid digestibility values.Comparing the digestibility values of amino acids with those of crude protein, it appeared that the latter revealed differences between the differently processed feather meals which were not shown by the former. Furthermore, we found negative correlations between in vivo and in vitro tests.The following general conclusions may be drawn from this experiment:a) processing can affect amino acid digestibility of feather meal indicating that prolonged time (longer than 30 min) and use of NaOH are not desirable; a study on the effect of shorter than 30 min processing periods would be of interest;b) crude protein digestibility estimations cannot be used as predictors of amino acid digestibility;c) laboratory (in vitro) tests are not reliable in detecting inferior protein/amino acid quality in differently processed feather meals;d) the variations between individual amino acids in their digestibility values are sufficiently extensive to suggest that, in the formulation of diets for poultry, it is essential that the dietary feather meal protein must be balanced on the basis of digested amino acids;e) the lanthionine present in test feather meals may be a reasonable indicator of treatment damage since the amino acid digestibility values of processed feather meals are inversely proportional to the lanthionine contents of the test samples.The digestibility of the individual amino acids in dietary feather meal has also been studied in broiler chicks by their changes in the intestinal contents (Chapter 4) and blood plasma (Chapter 5). In these nutritional-physiological studies the feather meals prepared in Chapter 3 were also used. The test feeds were given to the birds by force-feeding in 3 equal doses at 3 hr intervals, to insure an adequate and controlled intake and to get a uniform distribution of the passage of feed. Nitrogen-free diet, standard amino acid mixture and casein were used as reference diets. Intestinal amino acid concentrations in jejunal and ileal contents of chicks Were measured at 21 hrs after the last force-feeding. These concentrations reflected the relative digestion of dietary feather meal protein as affected by different processing conditions. Digesta taken from the jejunum showed higher levels of amino acids derived from the chemically treated feather meals and lower levels from the enzymatically treated ones. The variations between intestinal amino acid levels were more pronounced in ileal digesta, where samples derived from feather meals processed for 30 min showed the lower amino acid levels. This was true for feather meals treated with enzymes and for products without additions, while the chemically treated feather meals showed an inverse trend. It should be noticed that feather meals treated for 30 min and the enzymatically treated products had the higher amino acid digestibility values while the chemically treated products were less well digested (Chapter 3).Comparing the ileal digesta derived from chicks fed on nitrogen-free diet and standard amino acid mixture, there were differences in the proportions of meth ionine, leucine, tyrosine, histidine and proline. Comparing the ileal digesta with the excreta, there were very close similarities in the proportions of all individual amino acids, with the exception of cystine, indicating an insignificant microbial influence on amino acids in the large intestine.It can be concluded that:a) the composition of a nitrogen-free diet may influence the amount of endogenous amino acids. These findings in relation to the small differences between apparent and true amino acid digestibility values found in this study (Chapter 3), suggest that apparent digestibility determinations are reliable measures for practical purposes;b) the similarity of the proportions of amino acids in the ileal digesta and excreta derived from the test feather meals, as well as from the nitrogen free diet, indicates that digestibility values for feather meal amino acids based upon fecal analysis are not substantially different from those obtained by using ileal assays. Comparative studies of ileal and fecal amino acid digestibility may be needed in order to prove the validity of the very close similarity of ileal and excreta amino acid composition. It issuggested, how ever, that fecal analysis is a more practical and reliable criterion for routine amino acid digestibility determinations, from the point of view of applied nutrition.Plasma amino acid concentrations in broiler chicks were estimated at 1 hr after the last force-feeding. There was a relationship between plasma amino acid levels and the relative digestibility of the feather meal protein subjected to various processing treatments. Comparisons between dietary/digested amino acids and their levels in plasma revealed significant correlations for the essential but not for the non-essential ones. Possible reasons for the lack of a precise relationship between dietary/digested and plasma amino acids are discussed in section 5.5.It can be concluded that:- although blood plasma studies may provide useful information on the relative digestion of dietary feather meal, it seems difficult to interpret plasma amino acid changes as a practical quantitative measurement of amino acid digestibility.The final conclusion, referring to the points of investigation which are mentioned in the introductory chapter is that:a) Feather meal protein-amino acids are affected in both their contents and digestibility, by different processing conditions, time being the most significant one.b) Chemical methods (total amino acids, soluble nitrogen) and qualitative assays in blood plasma and intestinal amino acids are not adequate to evaluate feather meal protein quality as affected by different processing conditions.c) Feather meal must be evaluated by quantitative in vivo digestibility measurements of the individual amino acids and should be used in poultry rations on the basis of the digested amino acids it supplies.<p/
Stakeholder dynamics and the implementation of process innovations: the case of Lean thinking in a UK NHS Hospital Trust
No full textThis paper addresses the dynamics and mechanisms underpinning the trajectories and outcomes of process innovation. It deploys actor-network theory to explore the role of emergent stakeholder dynamics and networks in shaping the trajectory and outcomes of a project to implement Lean thinking (Lean) in a theatres unit of a UK National Health Service hospital. It traces the process of network formation, stabilisation and maintenance over time, and shows that different meanings for Lean become manifest during the implementation process, manifested through the emergence and mobilisation of a global and a local network that interact with each other using the project as a negotiation space in order to achieve their diverse interests
The role of actor associations in understanding the implementation of lean thinking in healthcare
No full textPurpose: The importance of networks in effecting the outcomes of change processes is well-established in the literature. Whilst extant literature focuses predominantly on the structural properties of networks, our purpose is to explore the dynamics of network emergence that give rise to the outcomes of process interventions. We show how Actor Network Theory (ANT) may be used as a lens for interrogating the way in which management interventions play out in the complex organisational setting of a UK National Health Service Trust, providing insights for management of process change initiatives. Design/methodology/approach: This is a rich qualitative study in the Pathology Unit of a UK National Health Service Trust, using ANT as the theoretical lens for tracking the emergence and transformation of networks of individuals over the course of a management intervention to promote “lean thinking” for performance improvements.Findings: ANT is useful for explicitly tracking how organisational players shift their positions and network allegiances over time, and identifying objects and actions that are effective in engaging individuals in networks enabling transition to a lean process. It is important to attend to the dynamics of the process of change and devise appropriate timely interventions enabling actors to shift their own positions towards a desired outcome.Research limitations/implications: We make the case for using of theoretical frameworks developed outside the operations management to develop insights for designing process interventions.Originality/value: By understanding the role of shifting networks managers can use timely interventions during the process implementation to facilitate the transition to lean processes: e.g. using demonstrable senior leadership commitment and visual communication.<br/
Gravitational-wave imprints of compact and galactic-scale environments in extreme-mass-ratio binaries
No full textCircumambient and galactic-scale environments are intermittently present
around black holes that reside in active galactic nuclei. As supermassive black
holes impart energy on their host galaxy, so the galactic environment affects
the dynamics of solar-mass objects around black holes and the gravitational
waves emitted from non-vacuum asymmetric binaries. Only recently an exact
general-relativistic solution has been found that describes a Schwarzschild
black hole immersed in a dark matter halo of the Hernquist type. We perform an
extensive analysis of generic geodesics delving in such non-vacuum spacetimes
and compare our results with those obtained in Schwarzschild, as well as
calculate their gravitational-wave emission. Our findings indicate that the
radial and polar oscillation frequency ratios descend deeper into the strong
gravity region as the compactness of the halo increases. This translates to a
redshift of non-vacuum geodesics and their resulting waveforms with respect to
the vacuum ones. We calculate the overlap between waveforms resulting from
Schwarzschild and non-vacuum geometries and find that it decreases as the halo
compactness grows, meaning that dark matter environments should be
distinguishable by space-borne detectors. For compact environments, we find
that the apsidal precession is strongly affected due to the gravitational pull
of dark matter; the orbit's axis can rotate in the opposite direction as that
of the orbital motion, leading to a retrograde precession drift that depends on
the halo mass, as opposed to the typical prograde precession transpiring in
galactic-scale environments. Gravitational waves in retrograde-to-prograde
alterations demonstrate transient frequency phenomena around critical
non-precessing turning points, thus they may serve as `smoking guns' for the
presence of compact dark matter environments around supermassive black holes.Comment: 19 pages, 10 figures, revisions regarding detectability and addition
of new figures and sections, abstract reduced to fit arxiv limits, accepted
for publication in PR
Reseña/Review (Papadopoulos, Dimitris, “Experimental practice: technoscience, alterontologies, and more-than-social movements”, Durham, Duke University Press, ISBN: 9781478000655-, 344 págs., 2018).
No full textObra ressenyada: Dimitris PAPADOPOULOS, Experimental practice: technoscience, alterontologies, and more-than-social movements. Durham : Duke University Press, 2018. ISBN: 9781478000655-, 344 pág
Scour below the toe of breakwaters: Investigation of scour formation through a geometrically open filter configuration located at the toe of a rubble mound breakwater lying upon sand
No full textScour formation at the toe of a rubble mound breakwater can lead to abrupt failure. Nowadays, counteraction of scour via geometrically closed filter rules, geotextiles or combinations is the common practice. Alternatively, in specific cases the use of geometrically open filters can save significant amount of time and decrease constructional costs. As a primary step towards this direction, the prediction of scour formation through a geometrically open filter can provide important information. Nevertheless, at this moment the knowledge upon this issue is insufficient and limited. A variety of recommendations occurs in literature, separately for toe design/scour protection and for the application of open filter criteria; however none of the studies treats these subjects combined. Therefore the objective of the present thesis is to get insight into scour formation and development through a breakwater toe lying upon sand and designed as a geometrically open filter. Thereby the research aims in drawing the link between scour characteristics with wave loading and filter configuration properties. In order to accomplish the research objective 2D physical model tests were conducted in the 25m long, 1m deep and 0.6m wide wave flume of DMC, installed in the company’s laboratory. In total, 23 tests were executed with irregular waves (Jonswap spectrum) and by varying wave loading and filter configuration properties. In particular, 5 different filter/base layer combinations were examined and 3 different wave conditions were used to investigate the effects of relative grain diameter, relative filter thickness, grading of filter layer, base layer stability Number and storm duration. Quantification of damage magnitude was accomplished via laser profile measurements of filter and base layer prior and after the execution of each test. Furthermore, wave particle velocity climate was determined via the use of an Electromagnetic Flow Meter (EMS) placed at the center of the toe. Finally, temporal evolution scour was captured through the side glass and was examined by digitizing and analyzing snap-shots from predefined time steps. Test results and observations have revealed the highly spatial character of scour formation. Nevertheless, tests with identical boundary conditions showed a surprising convergence in averaged maximum scour depth magnitude. In addition, in the majority of tests an S-curve erosion/deposition pattern was shaped while erosion started immediately at the downstream side of the box threatening breakwater stability. Equilibrium maximum scour depth was reached for less than half the data set; thus erosion process was still in progress. Based on this, two approaches were developed to investigate temporal evolution of scour. Furthermore, dimensional analysis and literature review have revealed the most important parameters that have significant effect in scour formation; their combination has led to the formation of a prediction tool. However, combination of the results from tests with different base materials would not be possible without the introduction of the base material stability Number (critical Shields’ Number). The derived tool is an empirical expression with limited physical background and range of validity. Additionally, it overestimates maximum scour depth due to a serious model effect; the different buoyancy between filter and base layer that was causing initial damage and damage exaggeration. Nevertheless, it is capable of delineating the relative contribution of each parameter in scour depth formation. For an overall view of scour formation, further research will be needed to provide a more accurate quantification of the interrelation between parameters that play a role in scour formation and development, and to implement the effect of missing parameters. Consequently the use of the derived expression as a scour prediction tool in real life is not yet recommended.Hydraulic EngineeringCivil Engineering and Geoscience
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
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