Gauge-Invariant Variables and Mandelstam Constraints in SU(2) Gauge Theory

The recent solution of the Mandelstam constraints for SU(2) is reviewed. This enables the subspace of physical configurations of an SU(2) pure gauge theory on the lattice (introduced solely to regulate the number of fields) with 3N physical degrees of freedom to be fully described in terms of 3N gauge-invariant continuous loop variables and N-1 gauge-invariant discrete +/-1 variables. The conceptual simplicity of the solution and the essential role of the discrete variables are emphasized. (Talk presented at QCD '94, Montpellier, France, 7-13 July 1994.)Comment: 8 pages plain Latex, CPT-94/P.306

The Shifted Coupled Cluster Method: A New Approach to Hamiltonian Lattice Gauge Theories

It is shown how to adapt the non-perturbative coupled cluster method of many-body theory so that it may be successfully applied to Hamiltonian lattice $SU(N)$ gauge theories. The procedure involves first writing the wavefunctions for the vacuum and excited states in terms of linked clusters of gauge invariant excitations of the strong coupling vacuum. The fundamental approximation scheme then consists of i) a truncation of the infinite set of clusters in the wavefunctions according to their geometric {\em size}, with all larger clusters appearing in the Schr\"odinger equations simply discarded, ii) an expansion of the truncated wavefunctions in terms of the remaining clusters rearranged, or ``shifted'', to describe gauge invariant {\em fluctuations} about their vacuum expectation values. The resulting non-linear truncated Schr\"odinger equations are then solved self-consistently and exactly. Results are presented for the case of $SU(2)$ in $d=3$ space-time dimensions.Comment: 13 pages + 5 postscript figures, plain Late

Evaluation of estuarine biotic indices to assess macro-benthic structure and functioning following nutrient remediation actions: A case study on the Eden estuary Scotland

© 2018 Despite a wealth of methods currently proposed by the European Water Framework Directive (WFD) to assess macro-benthic integrity, determining good ecological status (GES) and assessing ecosystem recovery following anthropogenic degradation is still one of the biggest challenges in marine ecology research. In this study, our aim was to test a number of commonly used structural (e.g. Shannon–Wiener, Average Taxonomic Diversity ([Formula presented]), M-AMBI) and functional indicators (e.g. BTA, BPc) currently used in benthic research and monitoring programmes on the Eden estuary (Scotland). Historically the estuary has a legacy of high nutrient conditions and was designated as a Nitrate Vulnerable Zone (NVZ) in 2003, whence major management measures were implemented in order to ameliorate the risk of eutrophication symptoms. We therefore collected data on intertidal macro-benthic communities over a sixteen year interval, covering a pre-management (1999) and post-management (2015) period to assess the effectiveness of the intended restoration efforts. In the post-management period, the results suggested an improvement in the structure and functioning of the estuary as a whole, but macro-benthic assemblages responded to restoration variably along the estuarine gradient. The greatest improvements were noticed in the upper and central sites of the estuary with functional traits analysis suggesting an increased ability of these sites to provide ecosystem services associated with the benthic environment such as carbon and organic matter cycling. Generally, almost all of the structural and functional indicators detected the prevailing environmental conditions (with the exception of (Pielou's index and Average Taxonomic Diversity ([Formula presented])), highlighting the appropriateness of such methods to be used in monitoring the recovery of transitional systems. This research also provides a robust baseline to monitor further management actions in the Eden estuary and provides evidence that notable reductions in nitrate concentrations resulting from NVZ designations may result in significant improvements to benthic structure and functioning

Comparing the network structure and resilience of two benthic estuarine systems following the implementation of nutrient mitigation actions

The structure and resilience of benthic communities in coastal and estuarine ecosystems can be strongly affected by human mediated disturbances, such as nutrient enrichment, often leading to changes in a food webs function. In this study, we used the Ecopath model (EwE) to examine two case studies where deliberate management actions aimed at reducing nutrient pollution and restoring ecosystems resulted in ecological recovery. Five mass-balanced models were developed to represent pre and post-management changes in the benthic food web properties of the Tamar (1990, 1992, 2005) and Eden (1999, 2015) estuarine systems (UK). The network functions of interest were measures related to the cycling of carbon, nutrients and the productivity of the systems. Specific attention was given to the trophic structure and cycling pathways within the two ecosystems. The network attribute of ascendency was also examined as a proxy for resilience and used to define safe system-level operating boundaries. The results of the resilience metrics ascendancy (A) and its derivatives capacity (C) and overhead (O) indicate that both systems were more resilient and had higher resistance to potential stressors under low nutrient conditions. The less perturbed networks also cycled material more efficiently, according to Finns cycling index (CI), and longer cycling path lengths were indications of less stressed systems. Relative Ascendency (A/C) also proved useful for comparing estuarine systems of different sizes, suggesting the Tamar and Eden systems network structures have remained within their pre-defined “safe operating zones”. Overall, this analysis presents justification that efforts to reduce nutrient inputs into the Tamar and Eden estuaries have had a positive effect on the trophic networks of each system. Moreover, the consensuses of the network indicators in both systems suggest ecological network analysis (ENA) to be a suitable methodology to compare the recovery patterns of ecosystems of different sizes and complexity

Fixing the conformal window in QCD

A physical characterization of Landau singularities is emphasized, which should trace the lower boundary N_f^* of the conformal window in QCD and supersymmetric QCD. A natural way to disentangle ``perturbative'' from ``non-perturbative'' contributions to amplitudes below N_f^* is suggested. Assuming an infrared fixed point persists in the perturbative part of the QCD coupling even below N_f^* leads to the condition \gamma(N_f^*)=1, where \gamma is the critical exponent. Using the Banks-Zaks expansion, one gets 4<N_f^*<6. This result is incompatible with the existence of an analogue of Seiberg duality in QCD. The presence of a negative ultraviolet fixed point is required both in QCD and in supersymmetric QCD to preserve causality within the conformal window. Evidence for the existence of such a fixed point in QCD is provided.Comment: 10 pages, 1 figure, extended version of a talk given at the QCDNET2000 meeting, Paris, September 11-14 2000; main new material added is evidence for negative ultraviolet fixed point in QC

Clean-in-place monitoring of different food fouling materials using ultrasonic measurements

Clean-in-Place is an autonomous technique used to clean the internal surfaces of processing equipment in thefood and drink sector. However, these systems clean for a longer time than required with negative economic andenvironmental impacts. In this work, an ultrasonic sensor system was developed to monitor the cleaning ofdifferent food fouling materials at laboratory scale. The fouling removal of three different food materials wasalso studied at different cleaning fluid temperatures. The three food materials had different cleaning mechanisms,which could be monitored successfully with the ultrasonic system. Tomato paste and gravy appeared to becleaned by mechanical forces whereas malt extract dissolved into the cleaning water. The results yielded fromthe cleaning of the malt was found to be repeatable whereas the tomato and gravy were more variable betweenrepeat experiments. It was found that changes in recorded ultrasonic signals were mainly affected by the area offouling that covered the transducer's active element

The effect of cellulose and starch on the viscoelastic and thermal properties of acid-swollen collagen paste

Collagen pastes are processed materials obtained through the swelling of minced bovine hides using acids into a fibrous swollen structure. Depending on the application, there is a need to improve the performance of these pastes in terms of rheological properties and mechanical strength of the final product. In this work, the addition of cellulose fibres and starch granules as fillers in acid swollen collagen paste was investigated. The influence of cellulose fibre length and starch granules with different amylose and amylopectin content on the viscoelastic and thermal properties of acid swollen paste were studied as a function of mixing ratio and collagen paste concentration. Addition of cellulose and starch granules resulted in an increase in the elastic modulus of the collagen paste with the starch granules having the highest impact. Addition of cellulose and starch also affected the tan δ peak of collagen paste at different collagen concentrations as a function of temperature. The micro differential scanning calorimetry (microDSC) results indicated that the denaturation temperature value of collagen was not influenced by the presence of cellulose and starch. However, upon reheating the denaturation temperature of collagen pastes wit starch granules shifted to lower temperatures

Near-infrared Spectroscopy and Hyperspectral Imaging for Sugar Content Evaluation in Potatoes over Multiple Growing Seasons

Sugar content is one of the most important properties of potato tubers as it directly affects their processing and the final product quality, especially for fried products. In this study, data obtained from spectroscopic (interactance and reflectance) and hyperspectral imaging systems were used individually or fused to develop non-cultivar nor growing season-specific regression and classification models for potato tubers based on glucose and sucrose concentration. Data was acquired over three growing seasons for two potato cultivars. The most influential wavelengths were selected from the imaging systems using interval partial least squares for regression and sequential forward selection for classification. Hyperspectral imaging showed the highest regression performance for glucose with a correlation coefficient (ratio of performance to deviation) or r(RPD) of 91.8(2.41) which increased to 94%(2.91) when the data was fused with the interactance data. The sucrose regression results had the highest accuracy using data obtained from the interactance system with r(RPD) values of 74.5%(1.40) that increased to 84.4%(1.82) when the data was fused with the reflectance data. Classification was performed to identify tubers with either high or low sugar content. Classification performance showed accuracy values as high as 95% for glucose and 80.1% for sucrose using hyperspectral imaging, with no noticeable improvement when data was fused from the other spectroscopic systems. When testing the robustness of the developed models over different seasons, it was found that the regression models had r(RPD) values of 55(1.19)–90.3%(2.34) for glucose and 35.8(1.07)–82.2%(1.29) for sucrose. Results obtained in this study demonstrate the feasibility of developing a rapid monitoring system using multispectral imaging and data fusion methods for online evaluation of potato sugar content

Feasibility of utilizing color imaging and machine learning for adulteration detection in minced meat

Meat products are popular foods and there is a need for cost-effective technologies for rapid quality assessment. In this study, RGB color imaging coupled with machine learning algorithms were investigated to detect plant and animal adulterants with ratios of from 1 to 50% in minced meat. First, samples were classified as either pure or adulterated, then adulterated samples were classified based on the adulterant's type. Finally, regression models were developed to predict the adulteration quantity. Linear discriminant classifier enhanced by bagging ensembling performed the best with overall classification accuracies for detecting pure or adulterated samples up to 99.1% using all features, and 100% using selected features. Classification accuracies for adulteration origin were 48.9–76.1% using all features and 63.8% for selected features. Regression trees were used for adulterant level quantification and the r (RPD) values were up to 98.0%(5.0) based on all features, and 94.5%(3.2) for selected features. Gray-level and co-occurrence features were more effective than other color channels in building classification and regression models. This study presents a non-invasive, and low-cost system for adulteration detection in minced meats

Microstructure and reconstitution of freeze-dried gum Arabic at a range of concentrations and primary drying temperatures

Freeze-drying is an energy intensive unit operation used for the production of dehydrated foods, such as instant coffee and dried fruits, and results in high sensorial, nutritional and reconstitution properties of the final products. Understanding the relationships between operating conditions and product quality is essential to design processes that are energy efficient, whilst producing high quality dried foods. In this work, the properties (microstructure and reconstitution) of freeze-dried gum arabic samples (with initial concentrations ranging between 20 and 60% solids by weight) were evaluated. The materials were dried at three different primary drying shelf temperatures, Ts (- 20, - 30 and - 40 ◦C). Sample temperatures recorded throughout freeze-drying were close to the pre-set Ts, with the exception of the 60% initial concentration system, where the sample was hotter than the shelf by 10–15 ◦C, in particular on increasing Ts. This was attributed to a combination of local temperature and pressure conditions that may have resulted in partial melting of the material. For the 20–50% systems, the properties of the freeze-dried materials were mainly affected by the initial concentration of the system, with increasing initial concentration generally resulting in lower porosities (ranging between 20 and 40%) and higher reconstitution times (ranging between 0.5 and 10min for 95% reconstitution). Pores were generally needle-shaped and <200 μm. Large (200–1800 μm), circular pores were observed in high initial concentration systems, and they were dominant in the microstructure of the freeze-dried 60% sample. The presence of these large bubbles was linked to the partial melting of the material, which enabled its expansion and puffing. For the 60% system, primary drying temperature had a profound effect on the properties of the freeze-dried solid, with samples dried at higher temperature showing higher porosity (e.g. 60–70% for Ts = -¬¬ 20◦C) and faster reconstitution rates (e.g. 3min for 95% reconstitution at Ts = - 20◦C). Overall, this study demonstrates the significance of formulation and shelf temperature on the porous structure of freeze-dried samples, which directly influences product performance