The radiant massive magnetic dipole Diaz Polanco, José; Ayala Hoffmann, José; Ujevic, Maximiliano
Classical and quantum gravity,
03/2024, Letnik:
41, Številka:
6
Journal Article
Recenzirano
Abstract
We present an exact, time-dependent solution for the Einstein field equations that models the coupling between an anisotropic fluid and a magnetic field in an axially symmetric space-time. ...By carefully selecting the metric components, we achieve a convenient separation of variables that enables us to solve Einstein's field equations and obtain a solution that evolves into the Gutsunaev-Manko massive magnetic dipole. The analysis of the thermodynamic quantities suggests that this solution may represent a pulse of radiation emitted by a massive object with magnetic properties as for example pulsars or neutron stars.
The purpose of this study is to analyze a possible substitution relationship between farmed gilthead seabream (Sparus aurata) and farmed European seabass (Dicentrarchus labrax) in Mediterranean ...markets. Seabream and seabass are the two most important aquaculture species in the Mediterranean area. Greece and Turkey are the main producing and exporting countries, while the main consumer markets are in Spain and Italy. Despite the fact that both species are produced by the same companies and use the same international logistics chains, there are no previous analysis regarding a potential competitive relationship between the two species. This work performs a cointegration analysis and tests for market integration between the two species in the frame of the competition across Greece and Turkey in the international market, considering Spanish and Italian seabream imports prices in the period 2009–2021. Results indicates that the substitution between seabass and seabream only takes place in a context of competition between producing and exporting countries, in which species from one country can indistinctly substitute any species from the competing country. On the contrary, when the supply of a given country is differentiated from the rest of the market, the two species will have a differentiated behavior.
Value chains and market access for aquaculture products Ababouch, Lahsen; Nguyen, Kim Anh Thi; Castro de Souza, Marcio ...
Journal of the World Aquaculture Society,
April 2023, 2023-04-00, 20230401, 2023-04-01, Letnik:
54, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Aquaculture contributes significantly to global food security, poverty alleviation, and international fish trade. Aquaculture products have become some of the most globalized food commodities, ...attracting the interest of diverse stakeholders that scrutinize industry developments, through the lenses of the global value chain (GVC) approach to analyze and understand the dynamics and roles at value chain nodes of key players, economic costs and benefits, value addition and value creation and to develop policy options and suitable market instruments for the promotion of sustainable aquaculture. Key characteristics of the aquaculture GVC are that most of the production takes place in developing countries, involving mostly small‐scale operators, while 60 to 70% of the demand (in value) occurs in Europe, North America, and Japan. As a consequence, the institutional and operational capacity of the producing countries is challenged to comply with increasingly demanding regulations and standards for consumer protection, social, and environmental requirements in order to participate actively in the aquaculture GVC. This article reviews the current status and the issues facing aquaculture value chains. It focuses on the challenges and perspectives for aquaculture value chain development, their main drivers, implications, and opportunities for the future of the aquaculture GVC.
This special issue of Aquaculture Economics & Management features five articles based on contributions to the International Association of Aquaculture Economics & Management (IAAEM) sponsored section ...on economics and marketing at the World Aquaculture Conference in New Orleans, Louisiana, February 19-22, 2015. The IAAEM session was conducted over 2 days with 36 presentations in the program. The presentations highlight the increased importance of aquaculture, as production and trade are expected to continue to increase. That implies that there are economic decisions to be made at all stages in the supply chain from input providers, in production, in the supply chain, and in addressing consumer preferences. This is largely reflected by the variety of topics addressed in this special issue. Although five articles in this special issue can never represent the full extent of topics and species that were covered in all presentations, they provide a fair indication of the variation when it comes to topics, but less so when it comes to species. It is worthwhile noting that, although there is an increasing focus on markets and demand, the special issue does not quite do justice to the many interesting contributions on the production side. It is also interesting to note how a number of the topics build on what was presented at Aquaculture Americas 2013 and 2014.
Stone, BL, Ashley, JD, Skinner, RM, Polanco, JP, Walters, MT, Schilling, BK, and Kellawan, JM. Effects of a short-term heat acclimation protocol in elite amateur boxers. J Strength Cond Res XX(X): ...000-000, 2022-Boxing requires proficient technical and tactical skills coupled with high levels of physiological capacity. Although heat and humidity negatively affect acute exercise performance, short-term exercise training in hot and humid environments can lead to physiological adaptations that enhance exercise performance in both hot and thermoneutral conditions. In highly trained endurance athletes, exercise-induced acclimation can occur in as little as 5 days (known as short-term heat acclimation STHA). However, the impact of a 5-day heat acclimation (5-DayHA) in combat athletes, such as elite amateur boxers, is unknown. The aim of the present investigation was to determine whether a 5-DayHA improves aerobic performance in a thermoneutral environment and causes positive physiological adaptations in elite boxers. Seven elite amateur boxers underwent a 5-DayHA protocol, consisting of 60-minute exercise sessions in an environmental chamber at 32 °C and 70% relative humidity. Repeat sprint test (RST) evaluated aerobic performance in a thermoneutral environment 24 hours before and after the 5-DayHA. Presession and postsession hydration status (urine specific gravity) and body mass were assessed. After a 5-DayHA period, boxers significantly improved RST performance (13 ± 7 to 19 ± 7 sprints, d = 0.92, p = 0.03) but not pre-exercise hydration status (1.02 ± 0.01 to 1.01 ± 0.01, d = 0.82, p = 0.07). Therefore, these findings suggest 5-DayHA enhances aerobic performance in elite-level amateur boxers and may provide a viable training option for elite combat athletes.
This work presents the results of price integration analysis in the gilthead seabream market in Spain (Sparus aurata). The main objective of this work is to analyze market delimitation and price ...transmission from the primary sector to the retail stage. It also aims to test the influence of international trade on domestic prices for different intra and extra EU seabream trade flows. International competition depending of the country of origin was studied considering Spanish ex-farm prices and Spanish import prices from Greece and Turkey. Price interactions mechanisms were studied by applying price transmission analyses considering ex-farm, wholesale and retail Spanish prices. Empirical analyses were developed using monthly prices for the period 2009–2016. The analysis at the import/ex-farm levels allows concluding that the fresh seabream market is delimited and price competitive. Domestic farmed seabream is affected by import prices. The evolution of prices is correlated and the products behave as substitutes. International competition is led by Turkish exports. The rest of participants, Greek exporters and Spanish farmers, adjust their prices according to the changes in those of Turkey. The analysis of price behavior along the value chain shows asymmetry in the transmission of prices. Spanish farmers are not transferring their costs to the following steps in the value chain since the price at wholesale and retail levels are not affected by changes in the ex-farm price. In contrast, the prices of domestic farmers are affected by those of imports and domestic traders.
•This study considers market integration and price transmission in the Spanish seabream market•Fresh seabream market in Spain is delimitated, price competitive and affected by import prices•Spanish farmers are not transferring their costs down the value chain•In contrast, the prices of domestic farmers are affected by those of imports
This paper extends the literature on price-integration in the gilthead seabream (Sparus aurata) market in Spain by shedding new light on established relationships using additional data allowing ...investigation of the importance of origin. Although the conclusions for the overall market are in the line of those previously reported for market integration and price transmission in the domestic value chain, there are significant differences in the relationships across the price series when the market is disaggregated by countries of origin. While the overall model, with minor differences, confirms Turkey's price leadership and the influence of domestic wholesalers on the changes in the price along the value chain, alternative models with more specific focus on the country of origin show how organization along the value chain and differentiation of domestic product provide different distribution channels and different mechanisms of price transmission. Domestic and international producers establish alliances with downstream agents both at national and international level depending on to the market targeted. Differentiation is exerted by domestic producers based on the origin of the product. Although producers have lower ability to influence downstream prices, they may be moving into a less volatile price scenario.
•Seabream prices are transmitted upstream in the Spanish domestic value chain.•International trade affects price linkages along the value chain in different ways.•Turkish imports exercise price leadership in the value chain.•Spanish retailers influence the price of Greek imports through large supply contracts.•Certain degree of differentiation is moving Spanish farmers to less price volatility.
Healthcare-associated infections pose a potentially fatal threat to patients worldwide and Staphylococcus aureus is one of the most common causes of healthcare-associated infections. S. aureus is a ...common commensal pathogen and a frequent cause of bacteremia, with studies demonstrating that nasal and blood isolates from single patients match more than 80% of the time. Here we report on a contemporary collection of colonizing isolates from those with methicillin-resistant S. aureus (MRSA) bloodstream infections to evaluate the diversity within hosts, and detail the clinical features associated with concomitant nasal colonization.
Swabs of the bilateral anterior nares were obtained from patients diagnosed with MRSA bacteremia. A single colony culture from the blood and an average of 6 colonies from the nares were evaluated for MRSA growth. For the nares cultures, we typed multiple isolates for staphylococcal protein A (spa) and derived the clonal complexes. Demographic and clinical data were obtained retrospectively from the electronic medical record system and analysed using univariate and multivariable regression models.
Over an 11-month period, 68 patients were diagnosed with MRSA bloodstream infection, 53 were swabbed, and 37 (70%) were colonized with MRSA in the anterior nares. We performed molecular typing on 213 nasal colonies. Spa types and clonal complexes found in the blood were also detected in the nares in 95% of the cases. We also found that 11% of patients carried more than one clone of MRSA in the nares. Male sex and history of prior hospitalization within the past 90 days increased odds for MRSA colonization.
The molecular epidemiological landscape of colonization in the setting of invasive disease is diverse and defining the interplay between colonization and invasive disease is critical to combating invasive MRSA disease.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The purpose of this work is to analyze the differences in profitability between European aquaculture firms of the Nordic and Mediterranean-EU regions, as well as the factors that are relevant to ...explain these differences. In addition to traditional factors proposed by theory to explain profitability differences among firms such as size, efficiency, or capital structure, we also include in this analysis the strategies of product differentiation and diversification through vertical integration. A sample of aquaculture firms of the Nordic and Mediterranean-EU regions that were operating over the 2012-2019 period are identified in the Orbis database and selected for this research, employing an unbalanced panel made up of 5,427 observations. To carry out this analysis, we propose a random-effects model of firm profitability that allows to test the effect of the different explanatory variables as well as their regional differences. The findings of this research support that Nordic and Mediterranean-EU aquaculture are two business models with different characteristics, what is reflected in the economic performance of their firms.
In contrast to the increasing aquaculture production of mussels worldwide, production in the European Union (EU) has shown a decreasing trend over the last two decades. Aquaculture production of ...mussels in the EU peaked in the late 1990s at more than 600 000 tonnes; by 2016, production volume had dropped by 20% to 480 000 tonnes. As mussel production represents more than ⅓ of EU aquaculture production, this decrease is an important contributor to the stagnation of EU aquaculture. Previous studies have suggested diseases, lack of mussel seed (spat), and low profitability as the main causes of the EU mussel production decrease. In this study, we investigate how economic and environmental factors have contributed. Moreover, we examine if the different mussel production techniques (raft, longline, on‐bottom, and ‘bouchot’) have been differently affected, by analysing the economic performance and cost structure evolution for the period 2010–2016. We complement these results with a SWOT (strengths, weaknesses, opportunities, and threats) analysis of the EU mussel sector based on expert knowledge.
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