Invariant feature extraction from event based stimuli

We propose a novel architecture, the event-based GASSOM for learning and extracting invariant representations from event streams originating from neuromorphic vision sensors. The framework is inspired by feed-forward cortical models for visual processing. The model, which is based on the concepts of sparsity and temporal slowness, is able to learn feature extractors that resemble neurons in the primary visual cortex. Layers of units in the proposed model can be cascaded to learn feature extractors with different levels of complexity and selectivity. We explore the applicability of the framework on real world tasks by using the learned network for object recognition. The proposed model achieve higher classification accuracy compared to other state-of-the-art event based processing methods. Our results also demonstrate the generality and robustness of the method, as the recognizers for different data sets and different tasks all used the same set of learned feature detectors, which were trained on data collected independently of the testing data.Comment: 6 page

Fourier transform infrared spectroscopy analysis of physicochemical changes in UHT milk during accelerated storage

The feasibility of using Fourier transform infrared spectroscopy (FTIR) to detect heat induced conformational rearrangements of proteins, protein-protein and protein-lipid interactions was studied with accelerated shelf-life protocols. Ultra-high temperature treated whole (WM) and skim milk (SM) were stored at 20, 30, 40 and 50 °C for 28 days. The changes leading to increased sedimentation in SM and WM at higher temperatures (≥40 °C) were observed during first 14 days of the storage period. Milk samples stored at 40 and 50 °C showed marked changes in the bands corresponding to conformations of milk lipids and formation of intermolecular β sheet of proteins, indicating protein-lipid interactions and aggregation. Dried sediment contained fat confirming protein-lipid participation in the sedimentation. FTIR was also able to detect changes that led to increased sedimentation in SM at temperatures lower than 40 °C, but only after 28 days

Electrophoretic characterization of protein interactions suggesting limited feasibility of accelerated shelf-life testing of ultra-high temperature milk

Accelerated shelf-life testing is applied to a variety of products to estimate keeping quality over a short period of time. The industry has not been successful in applying this approach to ultra-high temperature (UHT) milk because of chemical and physical changes in the milk proteins that take place during processing and storage. We investigated these protein changes, applying accelerated shelf-life principles to UHT milk samples with different fat levels and using native- and sodium dodecyl sulfate-PAGE. Samples of UHT skim and whole milk were stored at 20, 30, 40, and 50°C for 28 d. Irrespective of fat content, UHT treatment had a similar effect on the electrophoretic patterns of milk proteins. At the start of testing, proteins were bonded mainly through disulfide and noncovalent interactions. However, storage at and above 30°C enhanced protein aggregation via covalent interactions. The extent of aggregation appeared to be influenced by fat content; whole milk contained more fat than skim milk, implying aggregation via melted or oxidized fat, or both. Based on reduction in loss in absolute quantity of individual proteins, covalent crosslinking in whole milk was facilitated mainly by products of lipid oxidation and increased access to caseins for crosslinking reactions. Maillard and dehydroalanine products were the main contributors involved in protein changes in skim milk. Protein crosslinking appeared to follow a different pathway at higher temperatures (≥40°C) than at lower temperatures, making it very difficult to extrapolate these changes to protein interactions at lower temperatures

Unraveling the Influences of Sodium, Potassium, Magnesium, and Calcium on the Crystallization Behavior of Lactose

The inability of lactose to properly crystallize due to the presence of high amounts of salts poses significant hurdles for its downstream processing with some dairy waste streams such as acid whey. This study aimed to investigate the physicochemical and thermal behaviors of lactose in the presence of cations commonly present in acid whey. A model-based study was conducted, utilizing various cations (Mg, Ca, K, and Na) at concentrations (8, 30, 38, and 22 mM, respectively) that are typically found in acid whey. The research experiments were conducted using a factorial design. The thermal analysis of concentrated solutions revealed augmentation in the enthalpy of water evaporation in the presence of individual cations and their combinations in comparison with pure lactose (698.4 J/g). The degree of enthalpy increased following the order of Na+ (918.6 J/g), K+ (936.6 J/g), Mg2+ (987.0 J/g), Ca2+ (993.2 J/g), and their mixture (1005.4 J/g). This resulted in a substantial crystal yield decline in the exactly reversed order to that of the enthalpy. The greatest decline was observed in the presence of the salt mixture (63%) followed by Ca (67%) compared with pure lactose (79%). The yield reduction was also inversely related to the solubility of lactose. The presence of divalent cations appeared to play a role in the isomerization of lactose molecules observed using DSC and XRD diffractograms according to the disappearance of peaks related to β lactose. The effect of salts on the crystallization of lactose was a combination of cation–lactose interactions, changes in the solubility of lactose, ion–dipole interactions between water and cations, and changes in the structure of water molecules. By deviating the composition of acid whey, the crystallization of lactose can be enhanced, leading to the improved downstream processing of acid whey

Heat-Induced Changes in κ-Carrageenan-Containing Chocolate-Flavoured Milk Protein Concentrate Suspensions under Controlled Shearing

Milk protein dispersions containing added cocoa powder (1.5% (w/w)) and sucrose (7% (w/w)) and varying levels of κ-carrageenan (0.01, 0.03, or 0.05% w/w) were subjected to combined heat treatment (90 °C/5 min or 121 °C/2.6 min) and shear (100 or 1000 s−1) to investigate the heat stability of milk proteins. The application of shear led to a notable reduction in non-sedimentable proteins, resulting in an increase in the average particle size and apparent viscosity of the dispersions, particularly at high concentrations of k-carrageenan and elevated temperatures. This indicates that shear forces induced prominent protein aggregation, especially at higher κ-carrageenan concentrations. This aggregation was primarily attributed to the destabilisation of micelles and presence of loosely bound caseins within the κ-carrageenan network, which exhibited increased susceptibility to aggregation as collision frequencies increased due to shear

VARIATION OF STOMATAL CONDUCTANCE AND ITS CONTROLLING FACTORS OF DIFFERENT SPECIES IN A WET EVERGREEN FOREST IN THE MID·COUNTRY WET ZONE OF SRI LANKA

Stomatal conductance is a primary determinant of the net carbon balance and growth of differentplant species in a forest community. Because of its influence on transpirational water loss, stomatalconductance determines the water balance of a plant. As both carbon and water balances playimportant roles in survival and establishment of seedlings of different plant species in a forestcommunity, stomatal conductance has a direct influence on species composition and succession of aforest. Therefore, the main objective of the present study was to describe the inter-species variationof stomatal conductance in a wet, evergreen forest in the mid-country wet zone of Sri Lanka. Asecondary objective was to examine the variation of two parameters which could influence stomatalopening, namely incident light intensity and leaf temperature, and to see whether any directcorrelations can be established between stomatal conductance and the above parameters.This study was conducted in the Gannoruwa forest reserve in Kandy in September, 1997. 108 plantspecies which included all growth forms (i.e. trees, shrubs, herbaceous plants, vines and grasses)were found. Stomatal conductance was measured using a portable diffusion porometer which alsorecorded the incident light intensity ( in terms of photosynthetically-active radiation) and leaftemperature. Conductances of both upper and lower leaf surfaces were measured and total leafconductance was obtained by summing the two above measurements. In a given species, at leastthree plants were sampled.There were significant differences between species in lower surface conductance (gi), upper surfaceconductance (gu) and total leaf conductance (g). Except in one species, gl was greater than gu in allother species examined. Lower Surface Conductance/g, ) ranged from 17 to 1280 mmol m,2 S'I with amean of 175.8 += 8.9 mmol m ,2S'I whereas gu ranged from 2.36 to 252 mmol m,2 S'I with a mean of25.15 += 1.58 mmol m,2 S'I. The range of total conductance (g) was 20.45 - 1309.8 mmol m,2 S'Iwith a mean of 20 1.41 += 9.44 nunol m,2 S'I. The frequency distributions of aH three conductanceparameters (i.e. lower, upper and total) were skewed to the left with the respective median valuesbeing 132.5 (for gr ), 18.25 (gu) and 149.9 (g) mmol rn" S'I . Normality of the distributions whentested using the box plot technique, showed significant skewness to the left, Deletion of extremevalues did not improve normality significantly.The light intensities experienced by the leaves ranged from 2.5 to 1830 umol (PAR) m ,2S'I and theleaf temperatures ranged from 24.55 to 34.40 C. When all species were considered together, totalleaf stomatal conductance (g) had a significant positive correlation with light intensity. But, therewas no significant correlation between g and leaf temperature. Similar results were obtained whenlower and upper surface conductances were considered separately as well. There was a highlysignificant positive correlation between light intensity and leaf temperature. A multiple regressionanalysis showed that these two variables explained only 8% of the overall variation of leaf stomatalconductance. This infers species differences, interactions between species, and their response tovariations in light intensity and leaf temperature are more significant. Stomatal conductance ofditTerent species respond in ditTerent degrees to light and temperature variations.1\ cluster analysis allowed the 108 plant species examined to be grouped in to different categorieson the basis of their total leaf stomatal conductance (g). The different species groups could bebroadly related to their position in the successional sequence. It was found that the speciesestablished under the canopy on the forest floor generally had lower levels of g than thoseestablishing in canopy gaps. While many species of the latter group (growing in gaps) had the abilityto raise their stomatal conductance in response to increasing light intensity, most species of theformer group (growing under the canopy shade) could not respond to the occasional sunflecks thatare incident on them at different times of the day.

Formulation and characterisation of wheat bran oil-in-water nanoemulsions

Wheat bran oil (WBO) has been reported to have an important content of bioactive compounds, such as tocopherols, alkylresorcinols, steryl ferulates and other phenolic compounds; however, its poor solubility in water systems restricts its applications in the food industry. This study is focussed on the formulation of oil-in-water (O/W) nanoemulsions of WBO in order to improve the bioaccessibility of its active compounds. The influences of oil concentration, surfactant type and concentration, and emulsification method, on the droplet size and stability of the nanoemulsions were investigated. Response surface methodology was used to optimise the conditions for preparing stable nanoemulsions with the minimum droplet size. The optimal nanoemulsion was obtained when 1% of WBO and 7.3% of a surfactant mixture of Span 80 (37.4%) and Tween 80 (62.6%) were emulsified in water by high intensity ultrasonication for 50 s after pre-emulsification with a high speed blender during 5 min. The optimal nanoemulsion showed good stability over time and antioxidant and tyrosinase inhibitory activities, which make it suitable for use in food applications.This work is part of the GALANG project (Ref.: ITC-20113029) financed by the Spanish Government through CDTI