Smarter task assignment or greater effort: the impact of incentives on team performance

We use an experiment to study the impact of team-based incentives, exploiting rich data from personnel records and management information systems. Using a triple difference design, we show that the incentive scheme had an impact on team performance, even with quite large teams. We examine whether this effect was due to increased effort from workers or strategic task reallocation. We find that the provision of financial incentives did raise individual performance but that managers also disproportionately reallocated efficient workers to the incentivised tasks. We show that this reallocation was the more important contributor to the overall outcome

Desarrollo de embriones de bovino obtenidos por fecundación in vitro cultivados con células oviductales o medio condicionado y transferidos a hembras receptoras

Se comparó el desarrollo in vitro de ovocitos obtenidos de ovarios de vaca de matadero, madurados, fecundados y cultivados in vitro bajo dos sistemas. Los ovocitos fueron cultivados en un medio de maduración a 39 °C, 5 % de CO2 y humedad relativa de 95 % durante 22 horas. Posteriormente, fueron incubados con espermatozoides seleccionados a través de una gradiente discontinua de Percoll. La tasa de maduración nuclear y fecundación fueron de 93,7 % (74/79) y 76,9 % (50/65) respectivamente. Un total de 252 ovocitos fecundados fueron cultivados in vitro. El porcentaje de desarrollo in vitro a las 2 días post-inseminación (embriones de 4-8 células) fue de 62,7 % (64/102) para los cigotos cultivados con células oviductales y de 67 % (100/150) para los cultivados en medio condicionado (P0,05). El porcentaje de desarrollo de mórulas fue de 17,6 % (18/102) para los cigotos cultivados con células oviductales y de 13,3 % (20/150) para los cultivados con medio condicionado (P0,05). Se obtuvo una tasa de desarrollo del 15,7 % (16/102) de blastocistos para aquellos cigotos cultivados con células oviductales. No se obtuvo blastocistos a partir de cigotos cultivados en medio condicionado. Cuatro blastocistos fueron transferidos a dos hembras receptoras. A los 42 y 57 días se encontró la presencia de un feto en cada hembraThe in vitro development of matured and fertilized bovine oocytes was compared between two culture systems. Oocytes were collected by aspiration of follicles of 3-8 mm in diameter using an 18g needle. After morphological selection the oocytes were incubated at 39 0C, 5 % C02 y 95 % relative humidity, during 22 hours. Afterwards, oocytes were incubated with spermatozoa selected by Percoll gradient system. The rate of nuclear maturation and fertilization was 93,7 % (74/79) and 76,9 % (50/65), respectively. A total of 252 zygotes were cultured, 102 with oviductal cells and 150 in conditioned medium. The in vitro development on day 2 of culture (4- or 8-cell embryos) was 62,7 % (64/102) for the zygotes co-cultured with oviductal cells and 66,7 % (100/150) for the zygotes cultured in conditioned medium. The development to the morula stage was 17,6 % (18/102) for the zygotes co-cultured with oviductal cells and 13,3 % (20/150) for the zygotes cultured in conditioned medium. A statiscally significant difference was not found in the development of 4, 8-cell embryos or morula. The development of embryos up to the blastocyst stage was 15,7 % (16/102) for the zygotes co-cultured with oviductal cells. Two blastocysts were transferred to the uterine horn ipsilateral to the CL in two recipients by non-surgical embryo transfer. Pregnancy was confirmed by ultrasonography at 42 and 57 days detecting the presence of one conceptus in each animal. This work has shown that in vitro inseminated of bovine oocytes with espermatozoa prepared with modified BO and co-cultured with oviductal cells, can develop to the blastocysts stage, unlike those that were cultured with conditioned medium. Finally, it is important to mention that this is the first communication in Chile of pregnancy after in vitro fertilization of bovine oocyte

La estructura de poder en las tribus amigas de la provincia de Buenos Aires (1830-1850)

The objective of this work is to analyze the changes that occurred within the tribes of “indios amigos” located on the Buenos Aires frontier, as a consequence of the close relationship with white society. In this regard, the following issues will be examined: a) the influence of the ration system allocated to the tribes; b) the function that internal processes of change fulfilled in relation to the power of the chief; c) the existence of the border, which frames the transformations operated in these indigenous groups.El objetivo de este trabajo es analizar los cambios que se produjeron al interior de las tribus amigas situadas en la frontera bonaerense, como consecuencia del contado estrecho con  la sociedad blanca. Al respecto, se examinarán: a) la influencia que tuvo el sistema de raciones que percibían las tribus; b) la función que cumplieron procesos internos de cambio en relación al poder del cacique; c) la existencia de la frontera, que enmarca las transformaciones operadas en estos grupos indígenas

Allá lejos y hace tiempo. El fuerte de Carmen de Patagones en la primera mitad del siglo XIX

In 1779 the fort of Carmen de Patagones was founded in the South of the current province of Buenos Aires in response to the Borbons politics to ensure the territorial control of its colonial dominions. The purpose of the paper is to analyze the development of this town from its establishment to the Rosas government period, recognizing different stages. The first one makes reference to the process of occupation of the land through a particular relation with the native groups of the zone. In a second stage, the fort obtains a relative autonomy in the handling of its political and administrative matters. And in the third one, the government attempted –with relative success-  to limit this autonomy exerting a greater control on the life of the fort.En 1779, y respondiendo a la política borbónica de asegurar el control territorial de sus dominios coloniales, se fundó en el extremo sur de la actual provincia de Buenos Aires, el fuerte de Carmen de Patagones. El objetivo del trabajo es analizar el desarrollo de este poblado desde su asentamiento hasta el período rosista reconociendo distintas etapas. La primera hace referencia al proceso de ocupación de la tierra mediante una particular relación con los pueblos nativos de la zona. En un segundo momento el fuerte logra una relativa autonomía en el manejo de sus asuntos políticos y administrativos. Y, en una tercera etapa, el gobierno rosista intentó con cierto éxito limitar dicha autonomía ejerciendo un mayor control sobre la vida del fuerte

Artificial insemination in South American camelids and wild equids

An overview of the present status of the use of artificial insemination (AI) in South American camelids and wild equids is offered. Technical aspects of semen collection, dilution and cryopreservation have limited the development and use of AI in camelid and equid species. To-date, efficiency is low but progress has been made and viable offspring have been produced through the use of AI in domestic South American camelids using both fresh and frozen semen. The origin, composition, and function of the viscous component of camelid seminal plasma remain a mystery and an obvious area for future research. A better understanding of the normal constituents of seminal plasma will enable the rational design of semen extenders suitable for camelids. Post-thaw sperm viability is very low, and studies are needed to address questions of optimal freezing and thawing procedures as well as the insemination dose. The basis for differences in reported pregnancy rates with sexed and frozen semen in domestic equids, and the ultimate success of AI in wild equids will require continued research into the ‘‘stallion effect’’, extenders and cryoprotectants, optimal volume and number of spermatozoa, temperatures during handling, processing an transport, and insemination techniques. In both camelids and equids, research on domestic species under controlled conditions provides and excellent opportunity to develop effective semen handling techniques for application in wild and endangered species of the respective families

Uncertainty, sensitivity analysis and the role of data based mechanistic modeling in hydrology

International audienceIn this paper, we discuss the problem of calibration and uncertainty estimation for hydrologic systems from two points of view: a bottom-up, reductionist approach; and a top-down, data-based mechanistic (DBM) approach. The two approaches are applied to the modelling of the River Hodder catchment in North-West England. The bottom-up approach is developed using the TOPMODEL, whose structure is evaluated by global sensitivity analysis (GSA) in order to specify the most sensitive and important parameters; and the subsequent exercises in calibration and validation are carried out in the light of this sensitivity analysis. GSA helps to improve the calibration of hydrological models, making their properties more transparent and highlighting mis-specification problems. The DBM model provides a quick and efficient analysis of the rainfall-flow data, revealing important characteristics of the catchment-scale response, such as the nature of the effective rainfall nonlinearity and the partitioning of the effective rainfall into different flow pathways. TOPMODEL calibration takes more time and it explains the flow data a little less well than the DBM model. The main differences in the modelling results are in the nature of the models and the flow decomposition they suggest. The "quick'' (63%) and "slow'' (37%) components of the decomposed flow identified in the DBM model show a clear partitioning of the flow, with the quick component apparently accounting for the effects of surface and near surface processes; and the slow component arising from the displacement of groundwater into the river channel (base flow). On the other hand, the two output flow components in TOPMODEL have a different physical interpretation, with a single flow component (95%) accounting for both slow (subsurface) and fast (surface) dynamics, while the other, very small component (5%) is interpreted as an instantaneous surface runoff generated by rainfall falling on areas of saturated soil. The results of the exercise show that the two modelling methodologies have good synergy; combining well to produce a complete modelling approach that has the kinds of checks-and-balances required in practical data-based modelling of rainfall-flow systems. Such a combined approach also produces models that are suitable for different kinds of application. As such, the DBM model can provides an immediate vehicle for flow and flood forecasting; while TOPMODEL, suitably calibrated (and perhaps modified) in the light of the DBM and GSA results, immediately provides a simulation model with a variety of potential applications, in areas such as catchment management and planning

Quantitative analysis of basic fibroblast growth factor and vascular endothelial growth factor in human colorectal cancer.

Tumour growth is angiogenesis dependent. Some authors suggest a prognostic role of microvessel count in colorectal cancer. We tested the role of basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) in the switch to the angiogenic phenotype in 35 patients with colorectal cancer at different stages of disease. We evaluated the two angiogenic factors, by enzyme-linked immunosorbent assay (ELISA), in tumour, peritumoral mucosa, pathological mesenteric and peripheral blood. We used ten endoscopic intestinal biopsies and ten peripheral blood samples from healthy subjects as control. bFGF was significantly lower in tumour tissues and in peritumoral mucosas than in healthy mucosas, whereas VEGF was up-regulated in tumours but not in peritumoral mucosa. Both angiogenic factors were greatly increased in mesenteric blood. VEGF tumour and serum levels were significantly correlated with the stage of disease. bFGF tumour and serum concentration were not correlated with the stage of disease. The high levels of bFGF in mesenteric blood suggest that this growth factor might be abnormally released from tumour tissue and peritumoral mucosa and could function as an early effector in the switch to the angiogenic phenotype. In contrast, VEGF, whose levels show a significant correlation with the stage of disease, could act in a following step, supporting tumour progression

Acute stress impairs sensorimotor gating via the neurosteroid allopregnanolone in the prefrontal cortex

Ample evidence indicates that environmental stress impairs information processing, yet the underlying mechanisms remain partially elusive. We showed that, in several rodent models of psychopathology, the neurosteroid allopregnanolone (AP) reduces the prepulse inhibition (PPI) of the startle, a well-validated index of sensorimotor gating. Since this GABAA receptor activator is synthesized in response to acute stress, we hypothesized its participation in stress-induced PPI deficits. Systemic AP administration reduced PPI in C57BL/6J mice and Long-Evans, but not Sprague-Dawley rats. These effects were reversed by isoallopregnanolone (isoAP), an endogenous AP antagonist, and the GABAA receptor antagonist bicuculline and mimicked by AP infusions in the medial prefrontal cortex (mPFC). Building on these findings, we tested AP's implication in the PPI deficits produced by several complementary regimens of acute and short-term stress (footshock, restraint, predator exposure, and sleep deprivation). PPI was reduced by acute footshock, sleep deprivation as well as the combination of restraint and predator exposure in a time- and intensity-dependent fashion. Acute stress increased AP concentrations in the mPFC, and its detrimental effects on PPI were countered by systemic and intra-mPFC administration of isoAP. These results collectively indicate that acute stress impairs PPI by increasing AP content in the mPFC. The confirmation of these mechanisms across distinct animal models and several acute stressors strongly supports the translational value of these findings and warrants future research on the role of AP in information processing

Reducciones, blandengues y “el enjambre de indios del Chaco”: entre las guerras coloniales de frontera y las guerras de la revolución en el norte santafesino

El proceso revolucionario desarrollado en el espacio rioplatense desde 1810 desestabilizó las relaciones fronterizas entre las sociedades hispano-criollas y los grupos indígenas de la Araucanía, del área pampeano-patagónica y del Chaco. Esa situación convirtió a las parcialidades no sometidas al dominio colonial en importantes aliados de los bandos en conflicto. Esas alianzas, sin embargo, fueron muy inestables. El objetivo de este artículo es analizar el funcionamiento del dispositivo fronterizo santafesino conformado durante el siglo XVIII y desestabilizado con la crisis revolucionaria; se busca, asimismo, indagar en las características que adoptó la guerra revolucionaria en ese espacio provincial. </p