450 research outputs found
Bullish-Bearish strategies of trading: A non-linear equilibrium.
In this paper, we study a financial market where risk neutral traders are endowed with a signal which is perfectly revealing of the direction (but not the exact amount) of the liquidation value of a normally distributed risky asset. This type of information is known as bullish or bearish. When the signal is positive (negative) the traders buy (sell) the asset. This type of information is different with the type of information which is classically considered in the literature where informed traders are endowed with a perfect or a noisy signal. In this model, since the optimal trading strategy is not linear, the pricing schedule is also a non-linear function of the volumes. The main results are the following i) the price function is a non-linear Sigmo¨ıd-shaped function. ii) A monopolistic bullish-bearish type trader makes nearly thirty six percent of the profits she would have made with a perfect signal in a linear model `a la Kyle (1985). iii) In the presence of competition, the market reveals his private information quicker than in a noisy informed strategic oligopoly. Moreover, liquidity is no longer a monotonic increasing function of the number of competitors
L'Ă©levage du hotu en Wallonie
In various places in Wallonia, the alteration of the ecological integrity of our rivers has led, in the past, to the rarefaction of certain fish species, in particular ecologically sensitive heritage species such as rheophilic cyprinids. Although the physico-chemical and hydromorphological quality of the habitat has now improved, or is in the process of returning to a satisfactory level in many rivers, the natural recolonization of fish is sometimes slow and restoration or support stocking is necessary to accelerate this process or facilitate it in the most isolated sectors. The production of juveniles for restocking requires the mastery of all the rearing phases: reproduction of broodstock, larval rearing, grow-out of juveniles to marketable size, as well as the growth and sexual maturation of captive fish constituting new breeding stocks. After a description of the biology of the hotu, this book addresses the different stages of production, and considers the growth of larvae and juveniles under various rearing conditions and levels of intensification. Gathering all the knowledge acquired on the rearing of the hotu, it constitutes a technical guide intended for the fish farmer interested in the production of new species./En divers endroits de Wallonie, l'altération de l'intégrité écologique de nos rivières a conduit, par le passé, à la raréfaction de certaines espèces de poissons, en particulier des espèces patrimoniales écologiquement sensibles comme les cyprinidés rhéophiles. Si la qualité physico-chimique et hydromorphologique de l'habitat s'est aujourd'hui améliorée, ou est en voie de retrouver un niveau satisfaisant dans de nombreux cours d'eau, la recolonisation piscicole naturelle est parfois lente et des repeuplements de restauration ou de soutien sont nécessaires pour accélérer ce processus ou le faciliter dans les secteurs les plus isolés. La production de juvéniles destinés au repeuplement nécessite la maîtrise de l'ensemble des phases d'élevage : la reproduction des géniteurs, l'élevage larvaire, le grossissement des juvéniles jusqu'à la taille commercialisable, ainsi que la croissance et la maturation sexuelle de poissons captifs constituant des nouveaux stocks de reproducteurs. Après une description de la biologie du hotu, cet ouvrage aborde les différentes étapes de la production, et envisage la croissance des larves et juvéniles dans des conditions d'élevage et des niveaux d'intensification variés. Rassemblant l'ensemble des connaissances acquises sur l'élevage du hotu, il constitue un guide technique destiné au pisciculteur intéressé par la production de nouvelles espèces
L'Ă©levage du barbeau en Wallonie
In various places in Wallonia, the alteration of the ecological integrity of our rivers has led, in the past, to the rarefaction of certain fish species, in particular ecologically sensitive heritage species such as the rheophilic cyprinids. Although the physico-chemical and hydromorphological quality of the habitat has now improved, or is in the process of returning to a satisfactory level in many rivers, the natural recolonization of fish is sometimes slow and restoration or support stocking is necessary to accelerate this process or facilitate it in the most isolated sectors. The production of juveniles for restocking requires the mastery of all the rearing phases: reproduction of broodstock, larval rearing, grow-out of juveniles to marketable size, as well as the growth and sexual maturation of captive fish constituting new breeding stocks. After a description of the biology of the barbel, this book addresses the different stages of production, and considers the growth of larvae and juveniles under various rearing conditions and levels of intensification. It brings together all the knowledge acquired on barbel rearing and constitutes a technical guide for fish farmers interested in the production of new species./En divers endroits de Wallonie, l'altération de l'intégrité écologique de nos rivières a conduit, par le passé, à la raréfaction de certaines espèces de poissons, en particulier des espèces patrimoniales écologiquement sensibles comme les cyprinidés rhéophiles. Si la qualité physico-chimique et hydromorphologique de l'habitat s'est aujourd'hui améliorée, ou est en voie de retrouver un niveau satisfaisant dans de nombreux cours d'eau, la recolonisation piscicole naturelle est parfois lente et des repeuplements de restauration ou de soutien sont nécessaires pour accélérer ce processus ou le faciliter dans les secteurs les plus isolés. La production de juvéniles destinés au repeuplement nécessite la maîtrise de l'ensemble des phases d'élevage : la reproduction des géniteurs, l'élevage larvaire, le grossissement des juvéniles jusqu'à la taille commercialisable, ainsi que la croissance et la maturation sexuelle de poissons captifs constituant des nouveaux stocks de reproducteurs. Après une description de la biologie du barbeau, cet ouvrage aborde les différentes étapes de la production, et envisage la croissance des larves et juvéniles dans des conditions d'élevage et des niveaux d'intensification variés. Rassemblant l'ensemble des connaissances acquises sur l'élevage du barbeau, il constitue un guide technique destiné au pisciculteur intéressé par la production de nouvelles espèces
Development of an aquaponics pilot production linked to short food supply chains
Face aux défis environnementaux et à la demande alimentaire croissante au niveau mondial, l’aquaponie apparaît comme une technique innovante pour la production de poissons et de plantes comestibles. Grâce à ses nombreux avantages (faible consommation en eau, recyclage des nutriments, réduction des déchets, pas d’usage de pesticides), l’aquaponie est aujourd’hui perçue comme une méthode de production agricole durable, respectueuse de l’environnement, et permettant localement de renforcer la sécurité alimentaire et les liens sociaux. Ce document présente les résultats de recherche du projet Aqualoci (Développement d’un pilote d’aquaculture intégrée associé à un circuit court de distribution, FEAMP 2017-2022), porté par le CERER-Pisciculture. Grâce à la mise en place d’une unité pilote de production aquaponique et au suivi des performances de de deux modèles de production (tilapia et sandre), les résultats de ce projet dressent un bilan agronomique, hydrique, énergétique et économique de ce système de production, permettant de créer les bases nécessaires au développement d’une nouvelle activité de production aquacole intégrée en Wallonie
Eco-designing Aquaponics: A Case Study of an Experimental Production System in Belgium
Aquaponics is receiving a growing interest as an emerging technology that combines recirculating aquaculture practices and hydroponics to produce fish and vegetables. However, a proper eco-design is essential to limit the environmental burdens and to enhance the economic profitability. Life Cycle Assessment (LCA) and Life Cycle Costing (LCC) were here combined to estimate the environmental and economic impacts of a designed pilot indoor aquaponic system in Belgium. Results showed that energy consumption, infrastructure and water consumption represent the main critical issues to achieve both the environmental and economic sustainability of this aquaponic system
Factors Associated With Access to HIV Testing and Primary Care Among Migrants Living in Europe: Cross-Sectional Survey
BACKGROUND: There is a heavy and disproportionate burden of human immunodeficiency virus (HIV) infection among migrant communities living in Europe. Despite this, the published evidence related to HIV testing, prevention, and treatment needs for migrants is sparse. OBJECTIVE: The aim of this study was to identify the factors associated with access to primary care and HIV testing among migrant groups living in Europe. METHODS: A Web-based survey (available in 14 languages) was open to all people aged 18 years and older, living outside their country of birth in the World Health Organization (WHO) European area. Community organizations in 9 countries promoted the survey to migrant groups, focusing on those at a higher risk of HIV (sub-Saharan Africans, Latin Americans, gay or bisexual men, and people who inject drugs). Multivariable analysis examined factors associated with access to primary care and previous history of an HIV test. RESULTS: In total, 559 women, 395 heterosexual men, and 674 gay or bisexual men were included in the analysis, and 68.1% (359/527) of women, 59.5% (220/371) of heterosexual men, and 89.6% (596/664) of gay or bisexual men had tested for HIV. Low perceived risk was the reason given for not testing by 62.3% (43/69) of gay or bisexual men and 83.3% (140/168) of women and heterosexual men who reported never having tested for HIV. Access to primary care was >60% in all groups. Access to primary care was strongly positively associated with living in Northern Europe compared with Southern Europe (women: adjusted odds ratio, aOR 34.56 [95% CI 11.58-101]; heterosexual men: aOR 6.93 [95% CI 2.49-19.35], and gay or bisexual men: aOR 2.53 [95% CI 1.23-5.19]), whereas those with temporary residency permits were less likely to have access to primary care (women: aOR 0.41 [95% CI 0.21-0.80] and heterosexual men: aOR 0.24 [95% CI 0.10-0.54] only). Women who had experience of forced sex (aOR 3.53 [95% CI 1.39-9.00]) or postmigration antenatal care (aOR 3.07 [95% CI 1.55-6.07]) were more likely to have tested for HIV as were heterosexual men who had access to primary care (aOR 3.13 [95% CI 1.58-6.13]) or reported "Good" health status (aOR 2.94 [95% CI 1.41-5.88]). CONCLUSIONS: Access to primary care is limited by structural determinants such as immigration and health care policy, which varies across Europe. For those migrants who can access primary care and other health services, missed opportunities for HIV testing remain a barrier to earlier testing and diagnosis for migrants in Europe. Clinicians should be aware of these potential structural barriers to HIV testing as well as low perception of HIV risk in migrant groups.This project received funding from the European Union’s Seventh Framework Programme for research, technological development, and demonstration under EuroCoord grant agreement number 260694. IF was funded by a Doctoral Research Fellowship from the National Institute for Health Research (NIHR). The views expressed in this paper are those of the authors and not necessarily those of the National Health Service (NHS), the National Institute for Health Research (NIHR), or the Department of Health. Additional funding was received from Gilead Sciences Europe Ltd; NIHR Clinical Research Network, the United Kingdom; Foundation for AIDS Research and Prevention in Spain (FISPSE) Project 361036/10; Consortium of Biomedical Research in Epidemiology and Public Health, Spain; Spanish HIV Research Network for Excellence (RD06/006 and RD12/0017/0018); Research and Development Fund, Public Health Service of Amsterdam; and the Swiss HIV Cohort Study (project #727), supported by the Swiss National Science Foundation (grant #148522) and by the Swiss HIV Cohort Study research foundation. No funder had any role in the study, writing of the manuscript, or decision to submit for publication.S
Brief exposure of embryos to steroids or aromatase inhibitor induces sex reversal in Nile tilapia (Oreochromis niloticus)
peer reviewedThis study aimed to develop sex reversal procedures targeting the embryonic period as tools to study the early steps of sex differentiation in Nile tilapia with XX, XY and YY sexual genotypes. XX eggs were exposed to masculinizing treatments with androgens (17α-methyltestosterone, 11-ketotestosterone) or aromatase inhibitor (Fadrozole), whereas XY and YY eggs were subjected to feminizing treatments with estrogen analog (17α-ethynylestradiol). All treatments consisted of a single or double 4-h immersion applied between 1 and 36 h post-fertilization (hpf). Concentrations of active substances were 1000 or 2000 µg l-1 in XX and XY, and 2000 or 6500 µg l-1 in YY. Masculinizing treatments of XX embryos achieved a maximal sex reversal rate of 10 % with an exposure at 24 hpf to 1000 µg l-1 of 11-ketotestosterone or to 2000 µg l-1 of Fadrozole. Feminization of XY embryos was more efficient and induced up to 91 % sex reversal with an exposure to 2000 µg l-1 of 17α-ethynylestradiol. Interestingly, similar treatments failed to reverse YY fish to females, suggesting either that a sex determinant linked to the Y chromosome prevents the female pathway when present in two copies, or that a gene present on the X chromosome is needed for the development of a female phenotype
Does Persistence Explain ESG Disclosure Decisions?
Advocates of an increased focus on environmental, social, and governance (ESG) initiatives have argued that increased ESG disclosure is a necessary first step. Given the limited regulatory requirements on ESG disclosure, manager preferences serve as a primary determinant of ESG transparency. Using data on ESG disclosure from Bloomberg, I examine the extent to which disclosure persistence on the behalf of firm management, as proxied by managerial tenure, affects firms’ ESG disclosure strategies. Overall, I find that ESG disclosure quality and ESG disclosure variability are reduced as management tenure increases. Further, I find that the replacement of a firm’s CEO interrupts disclosure persistence, e.g., median ESG disclosure scores increase roughly 9.7% in the two years following the replacement of a firm’s CEO. The results of this study highlight one inhibitor, i.e., persistence, to inducing more complete, transparent ESG disclosure
Realizing stock market crashes: stochastic cusp catastrophe model of returns under time-varying volatility
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