Categories Of Eggs Research Articles

Fungal profile of eggshells from commercial and free-range hens of a supermarket chain in Fortaleza, CE, Brazil

Eggs are perishable and fragile foods because of their easy contamination by different microorganisms, such as fungi. Hence, research on egg safety and quality has been recently developed worldwide to minimize illness transmitted by this food, although most present mainly pathogenic bacteria. Thus, this study identified potentially pathogenic fungal species in eggshells from free-range and commercial hens offered in supermarkets in Fortaleza, CE, Brazil. The research was performed at the Vettings laboratory at the State University of Ceará (UECE) with 40 eggs: 20 from commercial and 20 from free-range hens. The eggshells were assessed using the dextrose evaluation method for pathogenic cultivation, commensal, and yeast fungi. Subsequently, readings were taken to identify and count the fungi on a binocular light microscope in 100x increments. Both egg categories showed a significant number of colony-forming units (CFU). The study identified eight different fungal species in both egg production types. The most prevalent fungal colonies in the free-range hen lineage (brown shell) were yeast spp. and Penicillium citrinum, and the laying hen lineage (white shell) had mostly Penicillium spp. and yeast spp. Therefore, both egg production systems showed similar fungal contamination, which suggests that the manipulation and/or storage are adequate despite the lack of strict food safety regulations or supervision for eggs in Brazil.

Fecundity of The Pine Processionary, Thaumetopoea Pityocampa (Denis & Schiffermüller, 1775) In The Case Of Reforestation In Moudjbara (Djelfa - Algeria)

A study of the fecundity of female populations of the pine processionary in the Moudjbara reforestation indicates that there are cyclical variations in the reproduction of this species. Descriptive analysis of pine processionary oviposition lengths showed greater significance for oviposition deposited on needles than for oviposition deposited on twigs. A very highly significant difference was noted between the lengths of the egg-laying supports from the Moudjbara reforestation (p=0.0001). The 195 pine processionary oviposition sites revealed a total of 37,272 eggs, with an average of 191 eggs per oviposition site. Analysis of the variance between the various categories of eggs showed a highly significant probability (p=0.0001). Three parasitoids were identified that emerged from oviposits collected at the Moudjbara reforestation site, with rates varying from year to year. T. embryophagum was encountered only sporadically in 2018, 2019 and 2021, with respective percentages not exceeding 2%. For the four pine processionary caterpillar populations studied, B. servadeii appeared to be more abundant than O. pityocampae. The number of B. servadeii adults observed reached 83.91% in 2020. Parasitoid activity was greater on eggs located at the ends of the clutch. It also appears that O. pityocampae mainly parasitizes the upper part of the egg, whereas B. servadeii shows a preference for the lower part.

A Computer Vision-Based Automatic System for Egg Grading and Defect Detection.

Defective eggs diminish the value of laying hen production, particularly in cage-free systems with a higher incidence of floor eggs. To enhance quality, machine vision and image processing have facilitated the development of automated grading and defect detection systems. Additionally, egg measurement systems utilize weight-sorting for optimal market value. However, few studies have integrated deep learning and machine vision techniques for combined egg classification and weighting. To address this gap, a two-stage model was developed based on real-time multitask detection (RTMDet) and random forest networks to predict egg category and weight. The model uses convolutional neural network (CNN) and regression techniques were used to perform joint egg classification and weighing. RTMDet was used to sort and extract egg features for classification, and a Random Forest algorithm was used to predict egg weight based on the extracted features (major axis and minor axis). The results of the study showed that the best achieved accuracy was 94.8% and best R2 was 96.0%. In addition, the model can be used to automatically exclude non-standard-size eggs and eggs with exterior issues (e.g., calcium deposit, stains, and cracks). This detector is among the first models that perform the joint function of egg-sorting and weighing eggs, and is capable of classifying them into five categories (intact, crack, bloody, floor, and non-standard) and measuring them up to jumbo size. By implementing the findings of this study, the poultry industry can reduce costs and increase productivity, ultimately leading to better-quality products for consumers.

Probabilistic risk assessment of dietary exposure to pentachlorophenol in Guangzhou, China

Pentachlorophenol (PCP) is a ubiquitous environmental contaminant commonly existing as its sodium salt (NaPCP), which enters the human body primarily through long term but low-level dietary exposure. PCP contributes to chemical carcinogenesis and teratogenesis. In this study, the probabilistic risk of dietary exposure to PCP in Guangzhou citizens was investigated. In total, 923 food samples in the categories of pork, livestock (beef and lamb), poultry, offal, eggs, and freshwater fish (considered to be relatively susceptible to PCP contamination) were collected from various markets in Guangzhou and tested for PCP. Probabilistic risk assessment model calculations for PCP dietary exposure and margin of exposure (MOE) values were performed using @RISK software, based on a Monte Carlo simulation with 10,000 iterations. The overall detection rate of PCP (above 1 μg kg−1, the detection limit) was 19.9% (184/923), with an average of 7.9 μg kg−1. The highest rate of PCP detection, 28.2%, was in livestock (beef and lamb). The MOE value for dietary PCP exposure in general Guangzhou residents averaged 400, which was far below 5,000 (the borderline for judging a health risk). The lowest MOE value, 190, was observed in the 3- to-6-year old population and indicates a significant risk. In conclusion, this study suggests that PCP exposure in Guangzhou residents is of considerable health risk, especially for the pre-school young children.

Preferência do Consumidor e Características de Qualidade em Ovos de Diferentes Categorias Comercializados nos Supermercados do Rio de Janeiro

ABSTRACT This study approached the consumer preference and characteristics of eggs from various categories sold at supermarkets in Rio de Janeiro. The study was performed in three phases. In the first one, 180 'caipira' eggs were randomly acquired from three supermarkets considering the consumers’ socioeconomic profile (middle, upper, and lower class). In the second phase, 456 eggs from conventional, free-range, 'caipira' and omega-3 enriched categories were obtained without considering the socioeconomic condition. After the acquisition, the eggs were taken for further analyses made the next day. The last phase was based on the perception and prevalence of consumers found in the second stage. This time, 443 consumers answered a Google Forms questionnaire. 'Caipira' eggs sold at supermarkets frequented by upper-class consumers maintained a better quality. When social class was discarded as a criterion, eggs from 'caipira', free-range, organic, and omega-3 enriched systems showed inferior quality compared to conventional eggs. The consumer preferences indicated that much misinformation regarding technical aspects of egg production persists, despite the increasing consumption of this protein source. In addition, the study revealed that many consumers still think there are hormone inputs in poultry farming, and they know very little about the production process or the differences among the egg categories for sale at Brazilian supermarkets.

Origins classification of egg with different storage durations using FT-NIR: A characteristic wavelength selection approach based on information entropy

The origin of fresh eggs is an essential determinant of their quality. This study's main goal was to classify fresh eggs' origins, after the characteristic wavelength from the near-infrared reflectance spectral of the eggs, using a support vector machine (SVM) for classification. To improve classification accuracy, eight categories of eggs were treated as classification targets. A Fourier transform near-infrared (FT-NIR) spectrometer was used to acquire spectral data of 800 eggs. A characteristic wavelength selection approach was presented based on information entropy (CWSABIE). Genetic algorithm-partial least squares (GA-PLS), interval partial least squares (iPLS), and competitive adaptive reweighting sampling (CARS) were compared. Standard normal variable transformation (SNV), Savitzky–Golay filtering, and Centralisation were applied to preprocess spectral data. The results indicate that when using CWSABIE with SNV, the model had the highest accuracy (93.8%) and can be used to classify the data of eggs after 15 days of storage (91.4%). The model show potential for application to online inspection for eggs from different storage days.

Development, Validation and Preliminary Experiments of a Measuring Technique for Eggs Aging Estimation Based on Pulse Phase Thermography.

Assessment of the freshness of hen eggs destinated to human consumption is an extremely important goal for the modern food industry and sale chains, as eggs show a rapid natural aging which also depends on the storage conditions. Traditional techniques, such as candling and visual observation, have some practical limitations related to the subjective and qualitative nature of the analysis. The main objective of this paper is to propose a robust and automated approach, based on the use of pulsed phase thermography (PPT) and image processing, that can be used as an effective quality control tool to evaluate the freshness of eggs. As many studies show that the air chamber size is proportional to the egg freshness, the technique relies on the monitoring of the air chamber parameters to infer egg aging over time. The raw and phase infrared images are acquired and then post-processed by a dedicated algorithm which has been designed to automatically measure the size of the air chamber, in terms of normalized area and volume. The robustness of the method is firstly assessed through repeatability and reproducibility tests, which demonstrate that the uncertainty in the measure of the air chamber size never exceeds 5%. Then, an experimental campaign on a larger sample of 30 eggs, equally divided into three size categories (M, L, XL), is conducted. For each egg, the main sizes of the air chamber are measured with the proposed method and their evolution over time is investigated. Results have revealed, for all the egg categories, the existence of an analytic relationship and a high degree of correlation (R2 > 0.95) between the geometric data of the air chamber and the weight loss, which is a well-known marker of egg aging.

Preços e rotulagem de ovos em supermercados de São Paulo

Brazil is a big table egg producer and consumer. Although battery cages are still the main production system in the country, growth in demand for specialty eggs can be identified from the growing availability of free-range and organic eggs in the market. The goal for this study was to report the prices of different table egg categories, varying in features such as eggshell color, package size or farming system, and to characterize the information available on labels. We investigated fifteen supermarket units, randomly distributed along the west side of the city of São Paulo, Brazil. Four data collections were performed throughout one year, in each unit. Our results indicate that organic eggs were the most expensive among different farming systems. Furthermore, brown shell eggs were more expensive compared to white shell eggs, regardless of the farming system. Eggs sold in small packages were more expensive than eggs sold in large packages. Cage-free and organic eggs had labels with more informative content and, lastly, eggs with more detailed labels were related to higher prices.

A Novel Composite Index for the Development of Decentralized Food Production, Food Loss, and Waste Management Policies: A Water-Climate-Food Nexus Approach

The United Nations has adopted 17 sustainable development goals for 2030 with environmental sustainability being one of the main pillars. A key point to address this pillar is the proper management of waste generation. Within the broad spectrum of waste types, food loss and waste is produced worldwide in large quantities. In this framework, the development of composite indexes is recommended to measure the level of compliance of any context with Sustainable Development Goals. This work presents a novel composite index for food loss and waste generation and management systems, the so-called sustainable development goals-food (SDG-Food) index, aiming to determine the level of compliance of any concrete national, regional, or local context regarding five different sustainable development goals with a water-climate-food nexus thinking. The pilot case study of Spain is presented by analyzing the environmental performance between 2015 and 2040 in a context of (i) compliance and (ii) non-compliance with the Paris Agreement targets. Additionally, four different diets are assessed. Results suggested a numerical index score of 13.79, highlighting the categories of eggs, cereals, meat, and vegetables, and the stages of agricultural production and consumption, as the furthers ones for compliance with the five SDG assessed. Moreover, the scenario of compliance with the Paris agreement targets presented better values for all stages, and a vegan diet was highlighted as the one with the best index score.

Polybrominated diphenyl ethers in foods from the Region of Valencia: Dietary exposure and risk assessment

Dietary exposure to polybrominated diphenyl ethers (PBDEs) of the population in the Region of Valencia, Spain, was assessed. A group of 320 composite samples of different fatty foods was collected and analyzed, including the following: vegetable oils, and foods of animal origin such as (a) fish and seafood, (b) eggs, (c) milk and dairy products, and (d) meat and meat products. Two scenarios were assumed for left-censored results: lower-bound (LB) and upper-bound (UB). Vegetable oils, and fish and seafood presented the highest content of PBDEs [mean values of 503 and 464 pg g−1 wet weight (ww) for total PBDEs, respectively, in the UB]. The dominating congeners were BDE47 in the food categories of fish and seafood, meat and meat products, and vegetable oils, and BDE99 in the categories of eggs, and milk and dairy products. The dietary exposure to PBDEs through consumption of the studied foods by the population in the Region of Valencia was estimated for adults (>15 years of age) and young people (6–15 years of age). Average intake levels (UB scenario) were 1.443 and 3.456 ng kg bw−1 day−1 for adults and young people, respectively. In a risk-assessment context, the margin of exposure (MOE) for congener BDE47, -99, −153, and −209 (ranged: 30-3E6) indicate that the current dietary exposure to these substances does not pose a risk to human health.

Determination of Potassium in Foodstuffs Consumed in Mamuju Indonesia by Neutron Activation Analysis

Potassium (K) is an essential nutrient and one of the main minerals in the blood as a counterweight to electrolyte and blood pressure. Decreasing K intake can be one of the causes of increased blood pressure. Mamuju is one area with high hypertension cases. Potassium is widely obtained from foodstuffs. In this study, food was collected from the markets in Mamuju Indonesia and analyzed using neutron activation analysis to determine K concentration. The results for the meat and egg category show that beef has a higher potassium concentration than chicken meat, and Negeri chicken eggs are higher than Kampung chicken eggs. For the vegetable category, six samples have very high concentrations of potassium, namely caisim, kemangi, fern leaves, chinese cabbage, spinach, and beans; and the spices namely turmeric and kencur have high concentrations of potassium. For the fish and seafood category, tilapia has the highest potassium concentration and the lowest shrimp. For staples, the highest concentration of potassium is found in potatoes, the lowest in sticky rice; and the processed soybeans, tempeh has a higher potassium concentration than tofu. Therefore, it is important to pay attention to daily potassium intake by looking at the combination of food and potassium concentration in it, such as by increasing consumption of vegetable foods. On the other hand, high potassium intake needs to be followed by a reduction in sodium and salt intake in food.

Copepod Embryonic Dormancy: "An Egg Is Not Just an Egg".

Long-lasting embryonic dormancy in invertebrates defies our understanding of what constitutes life because, for example, eggs of some copepods can delay hatching for decades or even centuries. Copepods, often millimeter-sized crustaceans, are some of the most numerous multicellular organisms on earth and are key organisms in most aquatic food webs. Some important free-living marine and estuarine species overwinter or oversummer by arrested embryogenesis in dormancy. The present contribution discusses the complex mechanisms behind embryonic dormancy by compiling knowledge from the 42 calanoid copepods from the superfamily Centropagoidea with well-described embryonic dormancy, which has been of scientific interest for decades. However, the determination of categories of copepod resting eggs-that is, diapause and quiescence, transitions between categories, the mechanisms controlling arrested development by the embryos, and how they interact with their surroundings-is not fully understood. Moreover, a clear link between the presence of the free-swimming population and their resting eggs in sediments is still not convincingly demonstrated. Here I evaluate the relative significance of potential cues driving the production of and the phase shift between egg categories. Understanding the initiation and termination of embryonic dormancy is of great importance for fundamental science-that is, population and food web ecology as well as climate science, aquaculture live feed, and ballast water research. Molecular techniques are developing rapidly, especially within health sciences, thus providing relevant tools applicable for plankton research. Here I suggest that applying molecular methods in addition to traditional physiological approaches in future research will lead to greater understanding of copepod embryonic dormancy, one of nature's wonders.

Altered actin cytoskeleton in ageing eggs of starfish affects fertilization process

Integrity of oocytes is of pivotal interest in the medical and zootechnical practice of in vitro fertilization. With time, oocytes undergo deterioration in quality, and ageing oocytes often exhibit compromised competence in fertilization and the subsequent embryonic development. With ageing oocytes and eggs of starfish (Astropecten aranciacus), we addressed the issue by examining changes of the subcellular structure and their performance at fertilization. Ageing eggs were simulated in two different experimental paradigms: i) oocytes were overmatured by 6 hours stimulation with 1-methyladenine (1-MA); ii) oocytes were removed from the gonad and maintained in seawater for 24 or 48 h before applying the hormonal stimulation (1-MA, 70 min). These eggs were compared with normally matured eggs (stimulated after isolation from the gonad with 1-MA for 70 min) with respect to the sperm-induced intracellular Ca2+ signaling and the structural changes of the egg surface. The cytoskeletal and ultrastructural differences in these eggs were assessed by confocal and transmission electron microscopy, respectively. In the two categories of ageing eggs, we have found remarkable structural modifications of the actin cytoskeleton and the cortical vesicles beneath the plasma membrane. At fertilization, these ageing eggs manifested an altered pattern of intracellular Ca2+ release, aberrant actin dynamics, and increased rate of polyspermy often despite full elevation of the fertilization envelope. Taken together, our results highlight the importance of spatio-temporal regulation of the actin cytoskeleton in the cortex of the eggs, and we postulate that the status of the actin cytoskeleton is one of the major determinants of the oocyte quality that ensures successful monospermic fertilization.

Impact of whole egg intake on blood pressure, lipids and lipoproteins in middle-aged and older population: A systematic review and meta-analysis of randomized controlled trials

Background and aimEffects of whole egg consumption on cardiovascular diseases (CVD) risk in the middle-aged and older population remain unclear due to inconsistent findings from observational and randomized controlled trials (RCTs). This meta-analysis aimed to assess the impacts of whole egg and egg category (whole eggs versus egg substitutes) intake quantity on CVD risk factors from systematically searched RCTs. Egg substitutes were hypothesized to have minimal effects of the blood lipid and lipoprotein profile as they are void of dietary cholesterol. Methods and resultsAs many as 434 studies identified from PubMed, Cochrane Library, CINAHL and Medline (Ovid) databases were screened and data were extracted from 8 selected RCTs. Quality of the selected studies were assessed and the overall effect sizes of weighted mean differences (WMD) were calculated using a random effects model. Non-differential effects in blood pressures, lipids and lipoproteins were observed when >4 whole eggs/week compared to ≤4 whole eggs/week were consumed. Intake of >4 whole eggs/week compared to equivalent amounts of egg substitutes caused greater elevations in blood total cholesterol (WMD: 0.198 mmol/L; 95% CIs: 0.056, 0.339), HDL cholesterol (WMD: 0.068 mmol/L; 95% CIs: 0.006, 0.130) and LDL cholesterol (WMD: 0.171 mmol/L; 95% CIs: 0.028, 0.315) but did not differentially affect triglycerides concentration. ConclusionOverall, the results support the notion that quantity of whole egg intake does not affect CVD risk factors and consuming egg substitutes may also be beneficial compared to whole eggs on lowering CVD risk in the middle-aged and older population.

Automated detection of parasitized Cadra cautella eggs by Trichogramma bourarachae using machine vision

Cadra (Ephestia) cautella (Walker) is a moth that attacks dates from ripening stages while on tree, throughout storage, and until consumption, causing enormous qualitative and quantitative damages, resulting in economic losses. Image-processing algorithms were developed for detecting and differentiating between three Cadra egg categories based on the success of Trichogramma bourarachae (Pintureau and Babaul) parasitization. These categories were parasitized (black and dark red), unparasitized fertile unhatched (yellow), and unparasitized hatched (white) eggs. Color, light intensity, and shape information was used to develop detection algorithms. Two image processing methods were developed based on three randomly selected images and were tested on a larger validation image set of 40 images: (i) segmentation and extractions of color and morphological features followed by Watershed delineation, and is referred to as Algorithm 1 (ALGO1), (ii) finding circular objects by Hough Transformation followed by convolution filtering, and is referred to as Algorithm 2 (ALGO2). ALGO1 and ALGO2 achieved correct classification rates (CCRs) for parasitized eggs of 92% and 96%, respectively. Their CCRs for unhatched eggs were 48% and 94%, and for hatched eggs were 42% and 73%, respectively. Regarding parasitized eggs, both methods performed satisfactorily, but, in general, ALGO2 outperformed ALGO1. These results ensure automatic evaluation of the efficiency of biological control of Cadra cautella by the egg parasitoid Trichogramma bourarachae by quantifying the rate of parasitization. The developed detection methods can be used by producers of biocontrol agents for online monitoring of Trichogramma and similar insect natural enemies during mass production and before release against crop pests. Moreover, with few adjustments these methods can be used in similar applications such as detecting plant diseases. Keywords: Trichogramma parasitization, Cadra eggs detection, machine vision, date fruit, image processing, objects recognition algorithms, biological control DOI: 10.25165/j.ijabe.20181103.2895 Citation: El-Faki M S, Song Y Q, Zhang N Q, El-Shafie H A, Xin P. Automated detection of parasitized Cadra cautella eggs by Trichogramma bourarachae using machine vision. Int J Agric & Biol Eng, 2018; 11(3): 94–101.

Studies on occurrence, characterisation and decontamination of emerging pathogenic Escherichia coli (STEC, ETEC and EIEC) in table eggs

ABSTRACT1. Escherichia coli is one of the most common facultative anaerobic species present in the gastrointestinal tract of animals and human beings. Usually they occur as commensals, but some serotypes can cause significant illnesses in humans as well as mammals and birds.2. The occurrence of E. coli in different categories of table eggs collected from markets was evaluated. Isolates were analysed for the presence of virulence genes, antibiotic susceptibility pattern and efficacy of peracetic acid and chlorine for the purpose of decontaminating table eggs.3. Significant differences were observed in the occurrence of E. coli between different groups viz. processed (cleaned, washed, sanitised and packed eggs), unprocessed (un-cleaned, un-sanitised and loose eggs) and free range (eggs obtained from backyard poultry) table eggs. Overall, E. coli occurred in table eggs at 28.6% with 22.9, 29.2 and 50.0% occurrence in processed, unprocessed and free-range table eggs, respectively.4. A total of 24 isolates of E. coli were obtained and screened for virulence genes viz. STH, SLT1/2 and INVE genes. Of the 24 isolates recovered, 10 typeable isolates belonged to O141, O119, O9, O120 and O101 serotypes, while the remaining 14 were untypeable. Antibiograms of the isolates showed multiple antimicrobial resistance (MAR) index in the range of 0.13–0.40.5. Peracetic acid (PAA) and chlorine (CL) were studied for their sanitisation efficacy; concentrations of 100 mg/kg of PAA and 200 mg/kg of CL completely inactivated E. coli over the egg surface and also resulted in 2.58 and 2.38 log reduction in total viable counts (TVC), respectively.6. The presence of virulence-associated shiga-like toxin (SLT1/2) and invasion E (INVE) genes and antimicrobial resistance among the emerging serotypes of pathogenic E. coli isolated from table eggs has public health implications. It underscores the need to implement better management practices across the production systems and marketing channels to produce E. coli-free wholesome eggs for consumers.

Effects of egg weight on the egg quality, chick quality, and broiler performance at the later stages of production (week 60) in broiler breeders

The objective of the present study was to determine the effect of broiler breeder egg weight on egg quality, chick quality, and broiler performance using Hubbard Classic broiler breeder flock. Hatching eggs from a commercial broiler breeder flock (Hubbard classic strain) were obtained at the age of 60 wk and divided into 3 egg-weight categories, namely small, medium, and large. For this purpose, 930 eggs having weights 63.09 ± 0.21, 68.85 ± 0.23, and 74.81 ± 0.11g were divided into 3 egg categories labeled small, medium, and large respectively. We further divided these eggs into 2 categories, eggs for quality parameters and eggs for incubation and posthatch performance parameters. Eggs from the small egg category had greater proportion of the shell weight and more shell strength. Egg weight did not significantly affect the albumen and yolk weight percentage. Egg weight affected the shape index and specific gravity for which lower values were observed for large eggs. Egg weight positively affected the chick weight, chick yield, and chick length (P < 0.05) of both male and female chicks. Results of the body weight gain showed that effect of egg weight on the posthatch performance of chick diminishes with the age of broilers. Egg weight significantly affected the body weight gain of male and female chicks up to 3 wk of age. Egg weights did not significantly affect the feed intake and mortality of broiler. Different egg-weight categories significantly affected the feed conversion ratio of female chicks at wk 2 and 3 of age and did not affect the feed conversion of male and female chicks at the end of wk 5. In conclusion, egg weight positively affected the chick characteristics (e.g., chick weight, chick length) and did not affect the final live body weight, feed conversion ratio, feed intake, and mortality in broilers.

Identification of eggs from different production systems based on hyperspectra and CS-SVM

ABSTRACT1. To identify the origin of table eggs more accurately, a method based on hyperspectral imaging technology was studied.2. The hyperspectral data of 200 samples of intensive and extensive eggs were collected. Standard normalised variables combined with a Savitzky–Golay were used to eliminate noise, then stepwise regression (SWR) was used for feature selection. Grid search algorithm (GS), genetic search algorithm (GA), particle swarm optimisation algorithm (PSO) and cuckoo search algorithm (CS) were applied by support vector machine (SVM) methods to establish an SVM identification model with the optimal parameters. The full spectrum data and the data after feature selection were the input of the model, while egg category was the output.3. The SWR–CS–SVM model performed better than the other models, including SWR–GS–SVM, SWR–GA–SVM, SWR–PSO–SVM and others based on full spectral data. The training and test classification accuracy of the SWR–CS–SVM model were respectively 99.3% and 96%.4. SWR–CS–SVM proved effective for identifying egg varieties and could also be useful for the non-destructive identification of other types of egg.

Influence of In-Isolation Properties of Geogrids on Their Pullout Performance in a Dense Graded Aggregate

A series of in-isolation and pullout tests was carried out on selected extruded (EGG) and non-extruded (NEGG) geogrid products that are available for base reinforcement and subgrade stabilization applications. The objective of the study was to examine the influence of selected geogrids index properties on their in-aggregate performance in roadway applications. The pullout tests were carried out in Oklahoma Department of Transportation (ODOT) Type-A aggregate, which is a dense-graded aggregate most commonly used in ODOT projects. Pullout tests provide useful information on the in-aggregate performance of geogrids outside the stress bulb directly beneath the tire pressure. The in-isolation properties studied included the geogrids low-strain (i.e. 2 and 5 % strain) rib strength, and ultimate rib strength and junction strength in both machine and cross-machine directions. Results of the study indicated that for both EGG and NEGG categories of geogrids examined, greater rib and junction strength properties overall resulted in greater pullout resistance. Geogrids junction strength and low-strain rib strength showed a reasonably strong correlation with their pullout performance regardless of the geogrid category examined. The rib strength at 2 % strain showed a stronger correlation than the 5 %-strain strength with the geogrid pullout performance. However, ultimate rib strength of geogrid showed convincing correlations with their pullout performance only when they were examined in separate categories with respect to their manufacturing technique (i.e. when the EGG and NEGG geogrids were examined as separate categories). The findings of this study are expected to be beneficial in relating the in-isolation properties of geogrids to their in-aggregate performance.

Is the reduced incubation time for B-eggs in Rockhopper Penguins Eudyptes chrysocome linked to egg density variation?

Crested penguins (genus Eudyptes) present a unique reversed egg-size dimorphism and hatching asynchrony, with the larger second-laid egg (B-egg) hatching before the smaller first-laid egg (A-egg). Both a higher water vapour conductance and parental favouritism during incubation could explain the shorter incubation period for the B-egg than for the A-egg. Because the incubation period is increased by the presence of a sibling for A-eggs, but not for B-eggs, and because both egg categories have the same incubation period when they are incubated alone, it has been suggested that the difference in incubation period was largely driven by the parental favouritism for B-eggs during incubation. We tested whether A- and B-eggs show a difference in laying density, density at the beginning of incubation and in density decrease during incubation according to the presence of a sibling. Although density at the start of incubation was significantly higher for B-eggs than for A-eggs, the decrease in density during incubation had the same slope for both egg categories. Moreover, the presence of a sibling did not influence densities. We additionally provide two equations that allow the back-dating of laying dates for a clutch of SouthernRockhopper Penguin (Eudyptes c. chrysocome) and we discuss the precision of the method (3.04 ± 2.29 days for A-eggs and 2.73 ± 2.10 days for B-eggs) for penguins which are increasingly being used as marine environmental sentinels.