Factors associated with postharvest ripening heterogeneity of "Hass" avocados (Persea americana Mill)

Indexación: Web of ScienceIntroduction. 'Hass' is the main avocado cultivar commercialized worldwide. The extended flowering period, very low percentage of fruit set and inability to ripen on the tree renders the fruit heterogeneous and unpredictable during postharvest management. The "triggered" and "ready-to-eat" growing markets for 'Hass' avocados are affected by the variable postharvest ripening or ripening heterogeneity which creates severe logistical problems for marketers and inconsistent quality delivery to consumers. Synthesis. The dry matter content, the current avocado harvest index that correlates very well with oil content, has been extensively used to harvest 'Hass' avocados to comply with the minimum standards to guarantee consumer satisfaction. However, previous work and empirical experience demonstrate that dry matter does not correlate on a fruit-to-fruit basis with time to reach edible ripeness. Thus, avocados of very different ages are harvested from individual trees, resulting in heterogeneous postharvest ripening of fruit within a specific batch. Several preharvest factors related to environmental and growing conditions and crop management as well as postharvest technology strategies influence the observed variability of postharvest ripening. Conclusion. Modern approaches based on studying the composition of individual fruits displaying contrasting postharvest ripening behavior, combined with non-destructive phenotyping techniques, seem to offer practical solutions for the fresh supply chain of avocados to sort fruit based on their ripening capacity.http://www.pubhort.org/fruits/2016/5/fruits160045.ht

Reducing complexity: An iterative strategy for parameter determination in biological networks

AbstractThe dynamics of biological networks are fundamental to a variety of processes in many areas of biology and medicine. Understanding of such networks on a systemic level is facilitated by mathematical models describing these networks. However, since mathematical models of signalling networks commonly aim to describe several highly connected biological quantities and many model parameters cannot be measured directly, quantitative dynamic models often present challenges with respect to model calibration. Here, we propose an iterative fitting routine to decompose the problem of fitting a system of coupled ordinary differential equations describing a signalling network into smaller subproblems. Parameters for each differential equation are estimated separately using a Differential Evolution algorithm while all other dynamic quantities in the model are treated as input to the system. The performance of this algorithm is evaluated on artificial networks with known structure and known model parameters and compared to a conventional optimisation procedure for the same problem. Our analysis indicates that the procedure results in a significantly higher quality of fit and more efficient reconstruction of the true parameters than the conventional algorithm

Paternity allocation in a mutant Heliothis virescens colony

Tobacco budworm, Heliothis virescens (F.) (Lepidoptera: Noctuidae), females can copulate multiple times creating the possibility for sperm competition. We used a colony lacking wild pigmentation on the wings (albino-type) for an experiment in which females double mated. Females copulated 2 days apart with two, 2-day-old males, one albino-type and one wild-type, or in the opposite sequence. A third of the females produced offspring from the first mate, and this group was significantly biased toward producing albino-type compared to wild-type progeny. A fourth of the females produced offspring from the second male exclusively and within this group was a significant bias toward wild-type compared to albino-type progeny. Almost half of the females produced offspring sired in equal proportions by both males simultaneously or in alternated paternities throughout all the reproductive life. These results suggest that regardless of the order in which moths mated, wild-type sperm had potential superior competitiveness. Therefore, sperm precedence is not the main driving force behind the paternity allocation mechanism in this strain of tobacco budworm

High bubble concentrations produced by ultrasounds in binary mixtures

7th Meeting of the European‐Society‐of‐Sonochemistry, BIARRITZ GUETHARY, FRANCE, MAY 14‐18, 2000International audienceIt was discovered that simultaneous insonification and air blowing of different aqueous binary solutions such as water/sodium‐dodecyl‐sulphate (SDS), water/methanol or water/potassium‐sulphate yields a very concentrated bubble cloud invading the whole vessel in a few seconds. After the end of insonification, this cloudiness remained in the solution for about 1 min. The phenomenon was investigated by computer‐treatment of solution pictures recorded every second after the end of insonification. Turbidity appeared to increase with ultrasound power, and also with SDS concentration. During the disappearance of the cloud, a turbidity front appeared rising and spreading upward. This front was studied in the characteristic plane and interpreted as a spatial segregation of different bubble sizes rising with different terminal velocities. The bubble sizes involved were estimated to about 10 mum. Adsorption of surface active species are invoked to explain the cloud formation and its abnormally slow disappearance, but the occurrence of the phenomenon for potassium‐sulphate salt remains unexplained

Researchers' Seedbeds for the Development of Research Skills in Universities

The objective of this study is to demonstrate the effects of the application of the pedagogical strategy "researcher's seedbed" in the development of research skills in universities. This research is of quasi-experimental, longitudinal and prospective design, where 2 groups were formed: control and experimental, of 18 students each. A validated instrument was used to measure the research competences, as well as a rubric for the evaluation of the research projects. It began with a pre-test, and after 14 weeks of the development of the strategy, through different educational sessions, the post-test was administered. Likewise, the research projects carried out were evaluated. The results obtained showed that the pedagogical strategy had a positive effect on the development of research skills, with the highest evaluation being found in 40% of the students, with statistically significant differences between the control and experimental groups (Mann Whitney U, p=0.007), and between the pre-test and post-test (Wilcoxon, p=0.00). In the development of cognitive and procedural competence, an effect was also found in the strategy, but not in the attitudinal competence (Mann Whitney U, p=0.496). The application of this study is based on the fact that the formation of research groups in universities strengthens formative research in higher level students. This study shows the benefits of the implementation of strategies for the development of research competencies, since the product will be to train professionals with a scientific culture in favor of society

Neural Observer Based Hybrid Intelligent Scheme for Activated Sludge Wastewater Treatment

Activated sludge wastewater treatment plants have received considerable attention due to their efficiency to eliminate biodegradable pollution and their robustness to reject disturbances. Different control strategies have been proposed, but most of these techniques need sensors to measure process main variables. This paper presents a discrete-time recurrent high order neural observer (RHONO) to estimate substrate and biomass concentrations in an activated sludge wastewater treatment plant. The RHONO is trained on-line with an extended Kalman filter (EKF)-based algorithm. Then this observer is associated with a hybrid intelligent system based on fuzzy logic to control the substrate/biomass concentration ratio using the external recycle flow rate and the injected oxygen as control actions. The intelligent system and neural observer performance is illustrated via simulations

The Effects of an Adaptive and Distributed Transmission Power Control on the Performance of Energy Harvesting Sensor Networks

The design of routing protocols for wireless sensor networks (WSNs) has been traditionally tackled by assuming battery-powered sensors, in which minimizing the power consumption was the main objective. Advances in technology and the ability to harvest energy from the environment has enabled self-sustaining systems and thus diminish the significance of network lifetime considerations in the design of WSNs. Although WSNs operated by energy-harvesting sensors are not limited by network lifetime, they still pose new design challenges due to the unstable and uncertain amount of energy that can be harvested from the environment. In this paper, we propose a new protocol for energy-harvesting sensor networks that uses adaptive transmission power to maintain the network connectivity, and distributes the traffic load on the network. Based on local information, each node dynamically adjusts its transmission power in order to maximize the network’s end-to-end performance. The simulation results indicate that the proposed protocol keeps the network connected at most of the times by using an efficient power management, outperforming greedy forwarding and dynamic duty cycle protocols in terms of packet delivery ratio, delay, and power management

Epigenetic Alteration of the Cancer-Related Gene TGFBI in B Cells Infected with Epstein–Barr Virus and Exposed to Aflatoxin B1: Potential Role in Burkitt Lymphoma Development

Burkitt lymphoma (BL) is a malignant B cell neoplasm that accounts for almost half of pediatric cancers in sub-Saharan African countries. Although the BL endemic prevalence is attributable to the combination of Epstein–Barr virus (EBV) infection with malaria and environmental carcinogens exposure, such as the food contaminant aflatoxin B1 (AFB1), the molecular determinants underlying the pathogenesis are not fully understood. Consistent with the role of epigenetic mechanisms at the interface between the genome and environment, AFB1 and EBV impact the methylome of respectively leukocytes and B cells specifically. Here, we conducted a thorough investigation of common epigenomic changes following EBV or AFB1 exposure in B cells. Genome-wide DNA methylation profiling identified an EBV–AFB1 common signature within the TGFBI locus, which encodes for a putative tumor suppressor often altered in cancer. Subsequent mechanistic analyses confirmed a DNA-methylation-dependent transcriptional silencing of TGFBI involving the recruitment of DNMT1 methyltransferase that is associated with an activation of the NF-κB pathway. Our results reveal a potential common mechanism of B cell transformation shared by the main risk factors of endemic BL (EBV and AFB1), suggesting a key determinant of disease that could allow the development of more efficient targeted therapeutic strategies

Critical analysis of the influence of transnational capitalism on institutions and organizations

This paper aims to analyze the development of capitalism and its influences on institutions and organizations from its beginnings to reach the highest stage in the processes of neoliberal economic globalization and the New Economy version with support of information and communication technologies. In raising this development from a critical analysis, it examines the impacts and effects on individuals, communities and the nation state. Subsequently it is questioned the scope of the imposed transnational neoliberal capitalism model. Finally, it is concluded that it needs a cultural transformation for not accepting the forms of domination, power and alignment of globalizing capitalism and to reconstruct the identity of communities through individual action and asserting collective self-determination, independence and self-management