Culture Cycle Research Articles

Can shrimp farming wastewater negatively affect water quality and zooplankton community structure of a Neotropical estuary? A case study during a productive cycle of Litopenaeus vannamei

Aquaculture wastewater can influence various communities’ structures in both marine and freshwater environments. This study describes the zooplankton community structure and environmental variables in both Passos River estuary (Northeast Atlantic, Brazil) and commercial shrimp farming ponds associated with this estuary. Samples for water quality analysis and quantification and identification of zooplankton were taken during a shrimp culture cycle (July to September 2014) from eight sites (two across the main channel, downstream and upstream, and six shrimp farming ponds). The main water quality parameters showed difference between the shrimp farming ponds and the Passos River estuary – higher levels of total phosphorus and chlorophyll-a were observed in the shrimp ponds. The zooplankton structure at different environments was dominated by the copepods (53.3 to 83.7%) and rotifers (9.2 to 35.5%) but no significant difference was observed among the individual densities. Meanwhile, nutrients availability was a key for high plankton densities in shrimp ponds. These findings have suggested that wastewater from shrimp farming did not influence the zooplankton community on a Neotropical estuary on a short-time scale.

Physical Attributes of Ferralsol in Fertigated Sugarcane Production Environments for Bioethanol in the Midwest of Brazil

Brazil is the world leader in the production and export of sugarcane derivatives, and its center-south region is the main producer. Fertigation with byproducts from bioethanol production can be adopted as a strategy to mitigate the soil physical deterioration resulting from the intensification of mechanized farming practices. The objective of this study was to evaluate the behavior of soil physical attributes under sugarcane cultivation in different crop cycles in fertigated areas in the midwest region of Brazil. The samples were collected in different Ferralsol layers (0.0–0.1, 0.1–0.2, 0.2–0.3, and 0.4–0.5 m) and fertigated crop cycles (first, third, fifth, seventh, and twelfth sugarcane cycles), as well as from native Cerrado vegetation (reference area), and the weight and volume relationships of the soil constituents and total soil were evaluated. Soil physical attributes are affected by sugarcane cultivation cycles and fertigation with vinasse. In the short term (third cycle), the results indicate deterioration of the physical attributes of the soil. However, throughout the cycles of sugarcane culture via fertigation (twelve cycles), the addition of vinasse leads to improvements in physical attributes and soil aggregation, promoting an increase in the longevity of the sugarcane crop. Therefore, the evaluation of the physical attributes of the soil in areas with vinasse application in different sugarcane cultivation cycles should be analyzed in areas of different regions, as this management practice indicates a high potential to increase the longevity of cultivation sugarcane, reducing production costs in the bioenergy sector.

Bacterial Community Patterns in the Agaricus bisporus Cultivation System, from Compost Raw Materials to Mushroom Caps.

Different from other fungal species that can be largely cultivated in 'axenic conditions' using plant material (e.g., species of Lentinula and Pleurotus in 'sterile' straw-based substrate), the commercial Agaricus bisporus cultivation system relies heavily on ecological relationships with a broad range of microorganisms present in the system (compost and casing). Since the A. bisporus cultivation system consists of a microbial manipulation process, it is important to know the microbial community dynamics during the entire cultivation cycle to design further studies and/or crop management strategies to optimize this system. To capture the bacterial community 'flow' from compost raw materials to the casing to the formation and maturation of mushroom caps, community snapshots were generated by direct DNA recovery (amplicon sequencing). The 'bacterial community flow' revealed that compost, casing and mushrooms represent different niches for bacteria present in the cultivation system, but at the same time, a bacterial exchange between microenvironments can occur for a portion of the community. Within each microenvironment, compost showed intense bacterial populational dynamics, probably due to the environmental changes imposed by composting conditions. In casing, the colonization of A. bisporus appeared, to reshape the native bacterial community which later, with some other members present in compost, becomes the core community in mushroom caps. The current bacterial survey along with previous results provides more cues of specific bacteria groups that can be in association with A. bisporus development and health.

Climate Change Impacts on Rice Cultivation: A Comparative Study of the Tonle Sap and Mekong River

Climate change is unequivocal. Farmers are increasingly vulnerable to floods and drought. In this article, the negative impact of climate hazards on rice cultivation in the Tonle Sap and Mekong River influenced by climatic variability between 1994 and 2018 are analyzed. A cohort of 536 households from four Cambodian districts participated in household surveys designed to consider how various vulnerability factors interacted across this time series. It was found that: (i) The major climate hazards affecting rice production between 1994 and 2018 were frequent and extreme flood and drought events caused by rainfall variability; (ii) In 2018, extreme flood and drought occurred in the same rice cultivation cycle. The impact caused by each hazard across each region were similar; (iii) An empirical model was used to demonstrate that drought events tend to limit access to irrigation, impact rice production, and result in an increased prevalence of water-borne diseases. Flood events cause reduced rice production, damage to housing, and impede children from accessing education. The impact of drought events on rice production was found to be more severe than flood events; however, each climatic hazard caused physical, economic, social, and environmental vulnerabilities. It is recommended that sufficient human and financial resources are distributed to local authorities to implement adaptation measures that prepare rice farmers for flood and drought events and promote equitable access to water resources.

P–216 Successful pregnancies and deliveries in patients with a recurrent failure of ART treatments following artificial removal of the zona pellucida (ZP) at the pronuclear stage

Abstract Study question Can a novel embryo culture method that artificially removes the ZP at the pronuclear stage yield successful pregnancy in patients with poor-quality embryos and/or blastocysts? Summary answer A blastocyst transfer after ZP-free culture can result in pregnancy for patients who cannot obtain good quality blastocysts from conventional culture methods. What is known already Perivitelline threads are been associated with the formation of cytoplasmic fragments. We had previously observed perivitelline threads in the adhesive region between the ooplasm and the ZP at the first cleavage in human embryos. We removed the ZP at the pronuclear stage in 71 abnormally fertilized oocytes (zygotes with three pronuclei), donated after conventional IVF (c-IVF), and termed them ZP-free 3PN. We found ZP-free 3PN embryos could be cultured without losing blastomere adhesions. Furthermore, the rate of good quality embryos was significantly higher in ZP-free 3PN embryos compared with ZP-intact embryos (ZP-intact 2PN/2PB and 3PN embryos; P < 0.05). Study design, size, duration This study was conducted in two cases selected among patients who underwent ART treatment in our clinic between 2018 and 2019. Cases were selected if they lacked good quality blastocysts in previous c-IVF/Intracytoplasmic Sperm Injection (ICSI) cycles due to massive cytoplasmic fragmentation at the first and second cleavage. We performed a clinical trial of ZP-free culture from December 2019 to March 2020. Participants/materials, setting, methods Two cases were selected for this trial. Normally fertilized oocytes were grouped as ZP-free or ZP-intact. For the ZP-free group, 2PN embryos were placed in 0.125M sucrose-containing HEPES to reduce ooplasm size, then ooplasms were completely separated from ZPs by a laser and pipetting. ZP-free and ZP-intact embryos were cultured with time-lapse imaging for up to seven days. Resultant blastocysts were either transferred into uterus or cryopreserved on Day5/6/7 for future embryo transfer cycles. Main results and the role of chance The ZP-free culture method was applied to two patients (patient A and B) with recurrent failure of ART in our clinic due to poor-quality embryos and/or difficulties in obtaining good quality blastocysts. In both cases, blastocysts were successfully obtained and cryopreserved for all ZP-free culture cycles. In patient A, one good quality ZP-free blastocyst was freshly transferred five days after oocyte retrieval, and a live male baby (2925g) was delivered at 40 weeks of gestation by caesarean section). In patient B, a frozen/thawed ZP-free blastocyst transfer was conducted, and a live female baby (3225g) was delivered at 39 weeks of gestation by vaginal delivery. This shows ZP-free culturing may help obtain viable embryos in patients for which conventional in vitro culturing methods result in embryos characterized with severe cytoplasmic fragmentation and poor quality in the early cleavage stage. Limitations, reasons for caution Although successful pregnancies and deliveries were confirmed in two cases, postnatal evaluations will be absolutely necessary for infants derived from ZP-free culture. In addition, the number of trial cases needs to be expanded, however careful selection of suitable patients is necessary for this novel culture method. Wider implications of the findings: We found removing the ZP at the pronuclear stage improved embryo development and led to successful pregnancies and deliveries after blastocyst transfer. This indicates ZP-free culturing may be an effective method for decreasing cytoplasmic fragmentation caused by perivitelline threads or adhesion between the ooplasm and the zona pellucida. Trial registration number Not applicable

Componentes de produção de cultivares de algodão (Gossypium hirsutum) no município de Confresa - Mato Grosso

A cultura do algodão se apresenta como uma alternativa rentável para os produtores, entretanto é de difícil manejo, possuindo diversas problemáticas que interferem durante o ciclo da cultura. O uso de algumas estratégias como a escolha da cultivar mais adaptada para a região, poderá diminuir a probabilidade de perdas e erros ao final do ciclo da cultura. Este trabalho teve como objetivo avaliar adaptabilidade e produtividade de dez cultivares de algodão no município de Confresa - MT. O experimento foi conduzido a campo aberto, utilizando o delineamento inteiramente casualizados, na qual observou-se as seguintes variáveis: produtividade, estande, altura, número de capulhos, número de aborto por planta e números de nó. Os resultados foram submetidos pelo software estatístico SISVAR e comparadas pelo teste de Scott-Knott (p < 0,5). A cultivar que se destacou em termos de produção de pluma foi a IMA 5801 B2RF.

Study on rapid formation of aerobic granular sludge promoted by addition of Fe2+

The aerobic granular sludge (AGS) process has been regarded as a promising sewage treatment technology. Compared with the activated sludge process, AGS process has the advantages of high efficiency and saving space. However, AGS process has several limitations in its application such as long cultivation cycle and easy disintegration. In this study, Fe2+ was added to the wastewater to cultivate AGS. The improvement on the cultivation of AGS with the addition of Fe2+ was investigated by analyzing the characteristics of AGS and the removal efficiency of pollutants. The results showed that adding Fe2+ (3~5 mg/L) to the reactor could effectively promote the formation of AGS. The sludge particles could be granulated within 7 days with the average particle size of more than 0.35 mm. In addition, the SEM showed that the dominant microorganisms were coryneform bacteria inside of the AGS. The XRD results indicates that the Fe2+ was converted into Fe2O3 presenting in AGS. The mixed liquid suspended solids (MLSS) and the sludge volume index at 30 min (SVI30) was 3.1 g/L and 40 mL/g, respectively, at the 40th day. The COD and NH4 +-N were effectively removed by AGS. This study could provide an effective approach for rapid formation of AGS.

Responses of different varieties of sugarcane to irrigation levels in the Cerrado

The Cerrado is under full expansion of sugarcane cultivation. However, the climate of this biome limits the production of sugarcane due to a marked water deficit. Therefore, the objective of this study is to evaluate different varieties of sugarcane in two cultivation cycles in response to irrigation levels in the Cerrado. The experiment was conducted in Goiânia-GO, Brazil, from March 2016 to March 2018, during the cycles of plant-cane and ratoon cane in pots. The experiment was completely randomized in a 5 x 6 factorial design. The treatments were five varieties of sugarcane (RB867515, CTC11, SP860042, IAC873396, and IAC911099) and six levels of supplementary irrigation (100, 80, 60, 40, 20 and 0% of the ETc determined by weighing lysimeter), and four replications. Eight biometric analyses were performed 45 days apart. At the end of each cycle, the quality of the raw material was determined through technological analysis. At the initial development phase (between March and August), when growth is low, we found that it is better to use an irrigation level that provides at least 40% of ETc, since the Cerrado environment does not increase sugarcane height. At the growth phase (between September and March), there is active growth corresponding to 74% of the cane's height. Therefore, the ideal irrigation is that at least 80% of the ETc be provided at the growth stage to support the sugarcane to reach a maximum growth and consequently favorable technological indexes. The supplementary irrigation level of 60% of ETc accelearted the process of maturation of sugarcane for a 12-month cycle. We conclude that the level of supplementary irrigation using greater technical viability for the cultivation of sugarcane in the Cerrado is 60% of the ETc. The varieties most adapted to this production environment are RB867515 and IAC873396

Identification of Micro-organisms (Parasites and Bacteria) which are Potential as Pathogenic Agent in Glass Eel of Anguilla spp. at the Eel Capture Location, Sukabumi, West Java

Eel (Anguilla sp.) is one of the important commercial fish in some countries particularly in East Asian countries such as Japan, South Korea, China, and Taiwan. The need of eel fry or frequently called as glass eel still relies on the natural capture. The issue of natural captured fish is the high level of bacterial infections and diseases. The dependence of glass eel from the nature provides an indication of infections of parasites and bacteria in glass eel. The existence of parasites and bacteria as microorganisms which are potential as pathogenic agents in the cycle of eel culture can be a serious obstacle, so that the glass eel handling needs a particular attention since the capturing proses from the nature. Therefore, identification of parasites and bacteria in the capture location of glass eel was necessarily conducted in Pelabuhan Ratu Bay, Sukabumi, West Java. The glass eel sampling was conducted in May-June 2019, in 3 locations of estuary with the highest capture yield namely Cimandiri River, Cikaso River and Cibuni River. The number of samples taken were 30 eels at each river location with 2 replicates, so that the total eel samples which were taken were 180 eels. Identification of parasites was conducted by examination of ectoparasite and endoparasite and dentification of bacteria was conducted by conventional method (biochemical method). Based on the result of identification, there was no parasite found in the glass eel samples, while bacteria found as many as 12 species and 3 dominant species namely Listeria sp. found in 40 eel samples with prevalence of 22.2%, Aeromonas hydrophila found in 28 eel samples with prevalence of 15.6%, and Staphylococcus spp. found in 22 eel samples with prevalence of 12.2%.Keyword : Micro-organism, Pathogen, Glass Eel, Anguilla spp.

Nutritional and Functional Evaluation of Inula crithmoides and Mesembryanthemum nodiflorum Grown in Different Salinities for Human Consumption.

The nutritional composition and productivity of halophytes is strongly related to the biotic/abiotic stress to which these extremophile salt tolerant plants are subjected during their cultivation cycle. In this study, two commercial halophyte species (Inula crithmoides and Mesembryanthemum nodiflorum) were cultivated at six levels of salinity using a soilless cultivation system. In this way, it was possible to understand the response mechanisms of these halophytes to salt stress. The relative productivity decreased from the salinities of 110 and 200 mmol L−1 upwards for I. crithmoides and M. nodiflorum, respectively. Nonetheless, the nutritional profile for human consumption remained balanced. In general, I. crithmoides vitamin (B1 and B6) contents were significantly higher than those of M. nodiflorum. For both species, β-carotene and lutein were induced by salinity, possibly as a response to oxidative stress. Phenolic compounds were more abundant in plants cultivated at lower salinities, while the antioxidant activity increased as a response to salt stress. Sensory characteristics were evaluated by a panel of culinary chefs showing a preference for plants grown at the salt concentration of 350 mmol L−1. In summary, salinity stress was effective in boosting important nutritional components in these species, and the soilless system promotes the sustainable and safe production of halophyte plants for human consumption.

Qualitative characteristics of the fungus Cyclocybe aegerita strains 2229, 2230, 2231 IBK under industrial cultivation conditions

Poplar mushroom is characterised by attractive fruiting bodies in terms of appearance and taste. Cyclocybe aegerita mushrooms are also known to contain unique substances, including proteins, polysaccharides, and aromatic substances with proven nutritional value and medicinal effects. However, the lack of a sound cultivation technology using available plant material limits the saturation of the domestic market with mushrooms of this species. Three strains of C. aegerita from the IBK National Collection of Agaricale Cultures of the Institute of Ecology and Natural Resources were studied for their potential introduction into commercial culture. It was determined that strains 2230 and 2231 have a vegetation cycle of 42 days compared to 46-64 days for the previously studied strains. The highest yield in the experiment was obtained for strain 2231, which ranged from 217 to 220 g per kilogram of a substrate over three cultivation cycles. The biological efficiency of the strains according to the results of the first wave of fruiting ranged from 20.2 (2229) to 60.4% (2231), which is consistent with the published data of other researchers. The appearance and parameters of the fruiting bodies of the strains, which differed in both the colour of the pileus and the size, were described in detail. Under microclimatic conditions of the experiment, strains 2230 and 2231 had a rich brown colour of pilei, while the formed fruit bodies of strain 2229 were distinguished by a pleasant milky cream colour. The largest fruiting bodies in terms of weight were obtained by cultivation of strain 2229 (7.5 ± 0.4 g), which is on average 2 g higher than the weight of mushrooms of other studied strains. The highest fruiting bodies were discovered in strain 2230 having a height of 91.0 ± 1.8 mm, which also had the widest pilei with a diameter of 29.5 ± 0.9 mm. The largest stem diameter, which reached an average of 10.8 ± 0.3 mm, was detected in the fruiting bodies of strain 2229. This study investigated the variability of morphological traits and identified trends in the number of fruiting bodies of a certain size in the total volume of collected mushrooms, which facilitates the design of packaging and marketing campaigns

Energy conversion efficiency in sugarcane cultivars as a function of production environments in Brazil

Energy production needs to increase in order to meet population and industrial growth in the coming decades, and clean energy that promotes the reduction of polluting gases in the atmosphere is required. Sugarcane is a crop with great potential for bioenergy production due to its high potential for converting solar energy into biomass. In this context, the questions arise: What is the real efficiency of conversion solar energy into biomass by sugarcane? How can the production environment and genetic diversity influence this process? In this sense, the objective of this work was to evaluate the efficiency of the conversion of solar energy into biomass, as well the available energy per hectare, and the productivity of stalks as a function of the production environment in different cultivars. The experiments were carried out in two production environments in Brazil, Prado Ferreira, Paraná State (Production Environment A) and Presidente Bernardes, São Paulo State (Production Environment C) and with three sugarcane cultivars SP80-3280, RB855156 and RB867515 in two cultivation cycles. This study showed: a) the production environment × genotype interaction causes 75.80% variation in stalk productivity; b) biomass productivity is less affected by water deficit than stalk productivity; c) the energy conversion efficiency (ECE) ranged from 2.80 to 4.54% in plant cane and 2.10–3.87% in ratoon cane cycles. The variation of ECE in the production environments was due to four main factors: greater water availability, soil fertility, air temperature and solar radiation.

Influence of shrimp farming activities on the phytoplankton community of a nearby estuary in Northeastern Brazil

The aim of this study was to evaluate the influence of shrimp farming on the phytoplankton community of a nearby shrimp estuary in Northeastern Brazil during a single cultivation cycle. Samples were collected from shrimp ponds and the estuary to analyse water quality variables, ecological indices and phytoplankton assemblages in both areas. Significant differences between sampling sites and over time were found for all variables. Phytoplankton density, orthophosphate and chlorophyll a content were lower in the estuary than in the ponds and were in accordance with Brazilian environmental law. Cyanophyta was abundant in the estuary and dominant in the shrimp ponds. Moreover, a significant positive correlation was found between Cyanophyta and orthophosphate. Thus, the influence of shrimp farming on the phytoplankton community was minimal or nil in the nearby estuary, as lower cell densities, a lower quantity of nutrients (especially orthophosphate) and better ecological health were found in the estuary than in the shrimp farm ponds. These findings contribute to a better understanding of the ecological balance in water bodies adjacent to aquaculture areas. Further studies should address the influence of wastewater from other aquaculture activities on the equilibrium of aquatic ecosystems.

Understanding the effect of shifting cultivation practice (slash-burn-cultivation-abandonment) on soil physicochemical properties in the North-eastern Himalayan region

Shifting cultivation (jhum cultivation), a common practice of converting forest land into agricultural land by slash and burn is threatening the ecosystem. This study assesses the effect of shifting cultivation cycles on soil quality in the North-eastern Himalayan region using a minimum of soil properties. To achieve this goal, a soil quality index (SQI) approach and multivariate techniques were used for surface (0-30 cm) and subsurface (30-70 cm) layers of soils in the forest, jhum land, and jhum fallow areas. The highest variability among land uses was found for clay content, SOC (soil organic carbon), exchangeable Mg and K, CEC (cation exchange capacity), and the Ca/Mg relationship. On the contrary, the lowest variation was recorded in bulk density (BD), porosity, and pH. The results of the principal component analysis (PCA) show BD, soil texture, available nitrogen (Nav), available phosphorus (Pav), available potassium (Kav), calcium (Ca) and sodium (Na) as the major indicators of soil quality. The study indicated that surface layers of forest soils have a lower soil quality when compared to jhum lands. Although jhum lands show a better soil quality compared to forests, their continued cultivation without any fertilisation and subsequent depletion of the soil nutrients can cause a degradation of soil quality as observed in jhum fallow lands. The use of these selected indicators for soil quality assessment was useful in terms of saving time and costs.

Long-Term Lime and Phosphogypsum Amended-Soils Alleviates the Field Drought Effects on Carbon and Antioxidative Metabolism of Maize by Improving Soil Fertility and Root Growth.

Long-term surface application of lime (L) and/or phosphogypsum (PG) in no-till (NT) systems can improve plant growth and physiological and biochemical processes. Although numerous studies have examined the effects of L on biomass and plant growth, comprehensive evaluations of the effects of this practice on net CO2 assimilation, antioxidant enzyme activities and sucrose synthesis are lacking. Accordingly, this study examined the effects of long-term surface applications of L and PG on soil fertility and the resulting impacts on root growth, plant nutrition, photosynthesis, carbon and antioxidant metabolism, and grain yield (GY) of maize established in a dry winter region. At the study site, the last soil amendment occurred in 2016, with the following four treatments: control (no soil amendments), L (13 Mg ha–1), PG (10 Mg ha–1), and L and PG combined (LPG). The long-term effects of surface liming included reduced soil acidity and increased the availability of P, Ca2+, and Mg2+ throughout the soil profile. Combining L with PG strengthened these effects and also increased SO42–-S. Amendment with LPG increased root development at greater depths and improved maize plant nutrition. These combined effects increased the concentrations of photosynthetic pigments and gas exchange even under low water availability. Furthermore, the activities of Rubisco, sucrose synthase and antioxidative enzymes were improved, thereby reducing oxidative stress. These improvements in the physiological performance of maize plants led to higher GY. Overall, the findings support combining soil amendments as an important strategy to increase soil fertility and ensure crop yield in regions where periods of drought occur during the cultivation cycle.

Cultural heritage adaptation is sustainable!

Sustainable development is a well-known term. Sustainable development includes development of cities and communities, industry and infrastructure, innovation and other areas, where no achievement would be possible without caring about the past – our cultural heritage. This paper explains the four-pillar principle of sustainable development of cultural heritage, where each pillar is an amalgamation of various domains. The need to pursue sustainable development of cultural heritage was pointed out in many reports by United Nations Educational, Scientific and Cultural Organization (UNESCO), International Council on Monuments and Sites (ICOMOS), Council of Europe, and others. These important organisations stress the need to preserve heritage, and adaptation is considered an effective means for it. This paper dwells on how and at which stage of cultural heritage life cycle the decision of adaptation should be taken, and what stages it should be preceded and followed by in order to ensure the said shift to sustainable development. The decision of adaptation is seen as a key milestone in the cyclical life of a heritage building, which needs to be set to guarantee the continuation of the building’s sustainable development.

Comparative performance of SARS-CoV-2 lateral flow antigen tests and association with detection of infectious virus in clinical specimens: a single-centre laboratory evaluation study

SummaryBackgroundLateral flow devices (LFDs) for rapid antigen testing are set to become a cornerstone of SARS-CoV-2 mass community testing, although their reduced sensitivity compared with PCR has raised questions of how well they identify infectious cases. Understanding their capabilities and limitations is, therefore, essential for successful implementation. We evaluated six commercial LFDs and assessed their correlation with infectious virus culture and PCR cycle threshold (Ct) values.MethodsIn a single-centre, laboratory evaluation study, we did a head-to-head comparison of six LFDs commercially available in the UK: Innova Rapid SARS-CoV-2 Antigen Test, Spring Healthcare SARS-CoV-2 Antigen Rapid Test Cassette, E25Bio Rapid Diagnostic Test, Encode SARS-CoV-2 Antigen Rapid Test Device, SureScreen COVID-19 Rapid Antigen Test Cassette, and SureScreen COVID-19 Rapid Fluorescence Antigen Test. We estimated the specificities and sensitivities of the LFDs using stored naso-oropharyngeal swabs collected at St Thomas' Hospital (London, UK) for routine diagnostic SARS-CoV-2 testing by real-time RT-PCR (RT-rtPCR). Swabs were from inpatients and outpatients from all departments of St Thomas' Hospital, and from health-care staff (all departments) and their household contacts. SARS-CoV-2-negative swabs from the same population (confirmed by RT-rtPCR) were used for comparative specificity determinations. All samples were collected between March 23 and Oct 27, 2020. We determined the limit of detection (LOD) for each test using viral plaque-forming units (PFUs) and viral RNA copy numbers of laboratory-grown SARS-CoV-2. Additionally, LFDs were selected to assess the correlation of antigen test result with RT-rtPCR Ct values and positive viral culture in Vero E6 cells. This analysis included longitudinal swabs from five infected inpatients with varying disease severities. Furthermore, the sensitivities of available LFDs were assessed in swabs (n=23; collected from Dec 4, 2020, to Jan 12, 2021) confirmed to be positive (RT-rtPCR and whole-genome sequencing) for the B.1.1.7 variant, which was the dominant genotype in the UK at the time of study completion.FindingsAll LFDs showed high specificity (≥98·0%), except for the E25Bio test (86·0% [95% CI 77·9–99·9]), and most tests reliably detected 50 PFU/test (equivalent SARS-CoV-2 N gene Ct value of 23·7, or RNA copy number of 3 × 106/mL). Sensitivities of the LFDs on clinical samples ranged from 65·0% (55·2–73·6) to 89·0% (81·4–93·8). These sensitivities increased to greater than 90% for samples with Ct values of lower than 25 for all tests except the SureScreen fluorescence (SureScreen-F) test. Positive virus culture was identified in 57 (40·4%) of 141 samples; 54 (94·7%) of the positive cultures were from swabs with Ct values lower than 25. Among the three LFDs selected for detailed comparisons (the tests with highest sensitivity [Innova], highest specificity [Encode], and alternative technology [SureScreen-F]), sensitivity of the LFDs increased to at least 94·7% when only including samples with detected viral growth. Longitudinal studies of RT-rtPCR-positive samples (tested with Innova, Encode, and both SureScreen-F and the SureScreen visual [SureScreen-V] test) showed that most of the tests identified all infectious samples as positive. Test performance (assessed for Innova and SureScreen-V) was not affected when reassessed on swabs positive for the UK variant B.1.1.7.InterpretationIn this comprehensive comparison of antigen LFDs and virus infectivity, we found a clear relationship between Ct values, quantitative culture of infectious virus, and antigen LFD positivity in clinical samples. Our data support regular testing of target groups with LFDs to supplement the current PCR testing capacity, which would help to rapidly identify infected individuals in situations in which they would otherwise go undetected.FundingKing's Together Rapid COVID-19, Medical Research Council, Wellcome Trust, Huo Family Foundation, UK Department of Health, National Institute for Health Research Comprehensive Biomedical Research Centre.

Organizational culture and knowledge cycle in the SMES of the tourist sector of the department of Caldas - Colombia

This article presents the results of a research that aims to determine the state of advancement of the life cycle of organizational knowledge related to the organizational culture in the SMEs of the tourism sector in the Department of Caldas, Colombia (part of the Eje Cafeteria region of Colombia). From a qualitative research, with a descriptive and correlational study, an evaluation model was applied in the SMEs of the tourism sector of the Department of Caldas (87% valued), from which it was found the consolidation of an organizational culture for the development of the life cycle of knowledge in the SMEs evaluated. With these results, it is expected to deepen the dynamics of business knowledge management and propose strategies that help improve processes and generate social wealth.

Estimation and forecasting of soybean yield using artificial neural networks

AbstractIn science, estimation is the calculation of a current value, while forecasting (or prediction) is the calculation of a future value. Both estimation and forecasting are based on covariates. However, whereas estimation enables greater agility in current decision making, forecasting can reveal different strategies for the future. The use of Artificial Neural Networks (ANNs) has brought improvements in accuracy to the estimation and forecasting of agricultural yield for various crops around the world. These models are part of a set of machine‐learning models, becoming an important ally not only to producers, companies, cooperatives, and to government institutions for decisions making and strategic decisions at all levels of the agricultural system. The main constraints of agricultural production are climatic conditions and soil water availability during crop cycles. We propose the use of ANNs for soybean [Glycine max (L.) Merr.] yield estimation and forecasting 2 mo before harvesting in the region of MATOPIBA, the largest and the last agricultural frontier of Brazil. This tropical agricultural area has about 73,173,485 hectares, corresponding to approximately 1.3 times the area of France. The input features for ANN were the monthly climatic conditions of air temperature, precipitation, and global radiation, as well as components of the water balance such as crop evapotranspiration, soil water storage, actual evapotranspiration, water deficiency, and surpluses during the cultivation cycle. The evaluation of ANN for yield estimation had R2 = .88 and RMSE = 167.85 kg ha–1, while the ANN for forecasting obtained R2 = .86 and RMSE = 185.85 kg ha–1.

The characterization of key physiological traits of medicinal cannabis (Cannabis sativa L.) as a tool for precision breeding

BackgroundFor millennia, drug-type cannabis strains were extensively used for various medicinal, ritual, and inebriant applications. However, cannabis prohibition during the last century led to cultivation and breeding activities being conducted under clandestine conditions, while scientific development of the crop ceased. Recently, the potential of medicinal cannabis has been reacknowledged and the now expanding industry requires optimal and scientifically characterized varieties. However, scientific knowledge that can propel this advancement is sorely lacking. To address this issue, the current study aims to provide a better understanding of key physiological and phenological traits that can facilitate the breeding of advanced cultivars.ResultsA diverse population of 121 genotypes of high-THC or balanced THC-CBD ratio was cultivated under a controlled environment facility and 13 plant parameters were measured. No physiological association across genotypes attributed to the same vernacular classification was observed. Floral bud dry weight was found to be positively associated with plant height and stem diameter but not with days to maturation. Furthermore, the heritability of both plant height and days to maturation was relatively high, but for plant height it decreased during the vegetative growth phase. To advance breeding efficacy, a prediction equation for forecasting floral bud dry weight was generated, driven by parameters that can be detected during the vegetative growth phase solely.ConclusionsOur findings suggest that selection for taller and fast-growing genotypes is likely to lead to an increase in floral bud productivity. It was also found that the final plant height and stem diameter are determined by 5 independent factors that can be used to maximize productivity through cultivation adjustments. The proposed prediction equation can facilitate the selection of prolific genotypes without the completion of a full cultivation cycle. Future studies that will associate genome-wide variation with plants morphological traits and cannabinoid profile will enable precise and accelerated breeding through genomic selection approaches.