896 resultados para sperm competition
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In this chapter we provide a summary description of Colombian Competition Policy with an emphasis on the agricultural sector. Key developments and recent changes in institutional arrangements affecting competition policy, as it applies to the agricultural sector, are highlighted. Illustrative case studies are depicted to show the richness and complexity of policy developments and enforcement. Some general conclusions are drawn from this examination.
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We set-up a two-sided market framework to model competition between a Prefered Provider Organization (PPO) and a Health Maintenance Organization (HMO). Both health plans compete to attract policyholderson one side and providers on the other side. The PPO, which is characterized by a higher diversity of providers, attracts riskier policyholders. Our two-sided framework allows to examine the consequences of this risk segmentation on the providers’ side, especially in terms of remuneration. The outcome of competition mainly depends on two effects: a demand effect, influenced by the value put by policyholders on providers access and an adverse selection effect, captured by the characteristics of the health risk distribution. If the adverse selection effect is too strong, the HMO gets a higher profit in equilibrium. On the contrary, if the demand effect dominates, the PPO profit is higher in spite of the unfavorable risk segmentation. We believe that our model, by highlighting the two-sided market structure of the health plans’ competition, provides new insights to understand the increase in the PPOs’ market share observed during the last decade in the US.
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We study competition in two sided markets with common network externality rather than with the standard inter-group e¤ects. This type of externality occurs when both groups bene t, possibly with di¤erent intensities, from an increase in the size of one group and from a decrease in the size of the other. We explain why common externality is relevant for the health and education sectors. We focus on the symmetric equilibrium and show that when the externality itself satis es an homogeneity condition then platforms pro ts and price structure have some speci c properties. Our results reveal how the rents coming from network externalities are shifted by platforms from one side to other, according to the homogeneity degree. In the speci c but realistic case where the common network externality is homogeneous of degree zero, platform s pro t do not depend on the intensity of the (common) network externality. This is in sharp contrast to conventional results stating that the presence of network externalities in a two-sided market structure increases the intensity of competition when the externality is positive (and decreases it when the externality is negative). Prices are a¤ected but in such a way that platforms only transfer rents from consumers to providers.
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This paper uses a two-sided market model of hospital competition to study the implications of di§erent remunerations schemes on the physiciansí side. The two-sided market approach is characterized by the concept of common network externality (CNE) introduced by Bardey et al. (2010). This type of externality occurs when occurs when both sides value, possibly with di§erent intensities, the same network externality. We explicitly introduce e§ort exerted by doctors. By increasing the number of medical acts (which involves a costly e§ort) the doctor can increase the quality of service o§ered to patients (over and above the level implied by the CNE). We Örst consider pure salary, capitation or fee-for-service schemes. Then, we study schemes that mix fee-for-service with either salary or capitation payments. We show that salary schemes (either pure or in combination with fee-for-service) are more patient friendly than (pure or mixed) capitations schemes. This comparison is exactly reversed on the providersíside. Quite surprisingly, patients always loose when a fee-for-service scheme is introduced (pure of mixed). This is true even though the fee-for-service is the only way to induce the providers to exert e§ort and it holds whatever the patientsívaluation of this e§ort. In other words, the increase in quality brought about by the fee-for-service is more than compensated by the increase in fees faced by patients.
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Resumen tomado de la publicaci??n
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The front speed of the Neolithic (farmer) spread in Europe decreased as it reached Northern latitudes, where the Mesolithic (huntergatherer) population density was higher. Here, we describe a reaction diffusion model with (i) an anisotropic dispersion kernel depending on the Mesolithic population density gradient and (ii) a modified population growth equation. Both effects are related to the space available for the Neolithic population. The model is able to explain the slowdown of the Neolithic front as observed from archaeological data
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A study of the spermiogenesis and spermatozoa of Helicolenus dactylopterus was conducted. Females of this species have the capacity to store sperm within their ovaries, and male gametes have a considerable cytoplasmic mass surrounding their heads to survive the long period of intraovarian sperm storage. Our observations show that early spermatids are round-shaped cells and have a spherical nucleus with diffuse chromatin. The nuclear volume decreases as a result of progressive chromatin condensation during spermiogenesis, causing the nucleus to take on a U-shape. Flagellar insertion is not central to the nucleus but consistently occurs at an oblique angle towards one side of it. The flagellum is inserted into the nuclear fossa, without subsequent nuclear rotation. In mature spermatozoa, the flagellum is adjacent to the nucleus. A comparison of the spermatozoa in the testicular lobules and those in the intraovarian storage structures suggests that the increase in volume of the cytoplasmic mass may occur in the posterior region of the testis, in the testicular duct. Spermatozoa enter the ovary in groups that reach the ovarian lumen and are surrounded by the ovarian epithelium for storage in sperm storage crypts
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L'ús d'esperma criopreservada en la inseminació artificial (IA) d'espècies d'interès productiu permet un major control sanitari i la creació de bancs de germoplasma d'alt valor genètic, entre d'altres avantatges. En el mercat porcí la major part de les inseminacions són encara realitzades amb semen refrigerat degut a l'èxit de l'aplicació de diluents de llarga durada i també a causa de la sensibilitat de l'esperma porcina a la criopreservació. Malgrat que aquesta sensibilitat ve donada per característiques particulars de la fisiologia espermàtica en l'espècie, algunes ejaculacions mantenen els paràmetres de qualitat espermàtica després de la criopreservació (ejaculacions amb bona "congelabilitat", GFEs) enfront d'altres que no sobreviuen al procés (ejaculacions amb mala "congelabilitat", PFEs). El primer objectiu de l'estudi va ser comparar ambdós grups en termes de fertilitat in vivo. El segon objectiu va ser testar l'eficiència de la inseminació postcervical (post-CAI) amb l'esperma criopreservada. El tercer objectiu va ser buscar predictors de la congelabilitat de les ejaculacions, tant en les GFEs com en les PFEs i en tres passos del procés de criopreservació (a 17ºC, a 5ºC i a 240 min postdescongelació). Aquest objectiu es va dur a terme mitjançant l'avaluació de paràmetres convencionals de qualitat espermàtica i a través de l'estudi de la localització i la reactivitat sota el microscopi de tres proteïnes (GLUT3, HSP90AA1 i Cu/ZnSOD) relacionades amb la fisiologia espermàtica i amb possibles rols en la congelabilitat. El quart objectiu va ser quantificar l'expressió de les tres proteïnes per transferència western, tant en espermatozoides d'ejaculacions GFEs com en els d'ejaculacions PFEs i en els tres passos abans esmentats, per tal de determinar el seu potencial com a predictores de la congelabilitat. Pel primer i el segon objectiu, 86 truges van ser inseminades per post-CAI amb 26 ejaculacions de mascles Piétrain dividides en una porció refrigerada a 17ºC (tractament control) i una porció criopreservada, ambdues porcions classificades alhora com a GFEs o PFEs. Els resultats més rellevants van demostrar que les probabilitats d'embaràs eren dues vegades menors en inseminacions amb esperma criopreservada d'ejaculacions PFEs (P < 0.05) que en inseminacions amb esperma criopreservada d'ejaculacions GFEs, fet que indica que les ejaculacions amb percentatges elevats d'espermatozoides mòbils progressius i d'integritat de membrana (per sobre del 40% en les GFEs) són més favorables a provocar embarassos que no pas aquelles ejaculacions amb una pobra funció espermàtica in vitro (PFEs). Ni el nombre de truges que van donar a llum, ni la quantitat de garrins, ni el risc de reflux espermàtic van ser significativament diferents entre les inseminacions amb esperma criopreservada d'ejaculacions GFEs i les inseminacions control amb semen refrigerat, la qual cosa demostra la bona aplicabilitat de la inseminació post-CAI amb l'esperma criopreservada. Finalment, pel tercer i quart objectius van ser criopreservades 29 i 11 ejaculacions de mascles Piétrain, respectivament. Dos paràmetres cinètics espermàtics, la linealitat (LIN) i la rectitud (STR), van mostrar una hiperactivació de la mobilitat superior en les ejaculacions PFEs que en les GFEs després de 30 min a 5ºC durant la criopreservació. A més, la combinació d'ambdós paràmetres va donar una fiabilitat propera al 72% en la predicció de la congelabilitat de les ejaculacions porcines. Tot i que no va ser possible predir la congelabilitat mitjançant l'avaluació de les tres proteïnes al microscopi, els resultats de transferència western van revelar diferències en l'expressió de la HSP90AA1 en l'esperma a 17ºC, molt possiblement relacionades amb la millor supervivència a la criopreservació dels espermatozoides d'ejaculacions GFEs. Aquests resultats suggereixen que la promoció de la criopreservació d'esperma porcina per la seva aplicació en IA passa pel desenvolupament de tests per la predicció de la congelabilitat en semen refrigerat.
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En aquesta tesi s'han dut a terme dos tipus d'estudis diferents. L'objectiu del primer era la preservació del semen de porcí a 15ºC i el del segon eren els co-cultius homòlegs de cèl·lules epitelials de l'oviducte i espermatozoides de porcí. Pel que fa al primer estudi, s'ha observat que l'addició de la prostaglandina F2α i àcid hialurònic a les dosis seminals no malmena la qualitat espermàtica i que la tolerància dels espermatozoides als canvis d'osmolalitat del medi es pot correlacionar proves de fertilitat i prolificitat.. Respecte el segon, s'ha determinat que les cèl·lules oviductals afecten els paràmetres espermàtics i que la presència d'espermatozoides sobreexpressa els gens que codifiquen per les proteïnes de xoc tèrmic. Així, se suggereix que aquestes proteïnes tenen algun paper en els processos reproductius que tenen lloc a l'oviducte, malgrat que s'hagi observat, mitjançant la tècnica de la interferència de l'RNA, que la HSP90AA1 no està implicada en el perllongament de la viabilitat espermàtica.
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The paper attempts to explore the interrelation between a) the architects’ individualism and “pre-structures” b) research- based findings during the design process through experimentation and c)an integrated design approach, where morphology, construction and bioclimatic design are integrated from an early design stage. Through a thorough presentation and analysis of a competition proposal for the Cyprus News Agency, we discuss a number of important findings in relation to the present and possibly future form of the design studio. We suggest that the designer’s “prestructures” may not only be the basis for creative action, but also the basis for understanding and interpretation. Design informed and enriched at every stage by a research-based process, might well be the transmission and transformation of “prestructures”, a process of elaboration and discovery which facilitates and enhances design creativity and possibly allows for a multiplicity of approaches through a range of possibilities. Furthermore, an integrated approach from the early stages of the design process facilitates innovation in materials and systems.
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In most EU member states, the business services industry has booked no productivity growth during the last two decades. The industry’s performance in the other member states was weaker than that of its US counterparts. Exploring what may be causing this productivity stagnation, this policy brief reports that weak competition has contributed to the continuing malaise in European business services. The study analyzed the persistence (over time) of firm-level inefficiencies. The evidence further suggests that competition between small firms and large firms in business services is weak. Markets for business services work best in countries with flexible regulation on employment change and with low regulatory costs for firms that start up or close down a business. Countries that are more open to foreign competition perform better in terms of competitive selection and productivity. The policy simulations in this paper show that greater import openness strengthens competition in business services markets. The largest positive impact comes from lower regulatory barriers for growing and shrinking firms. More particularly, competitive selection would be fostered by a reduction of administrative and regulatory costs related to labour contracts, bankruptcy and start-up requirements. A key element of the European Commission’s Europe-2020 strategy is the Single European Market for Services. Business services form one of the largest industries in Europe – and given its productivity stagnation, it deserves to be a priority target of the Europe-2020 strategy. Improving the way the business services market functions may have large positive knock-on effects for the EU economy.