Abatement of Nitrate Pollution in Groundwater and Surface Runoff from Cropland Using Legume Cover Crops with No-Till Corn

Agricultural practices can have a significant impact on water quality. The effects of leguminous winter cover crops on leaching of NO-3; from soil have been investigated in this project. Legume cover crops, by fixation of atmospheric N, can reduce the amount of fertilizer N required to produce summer grain crops. The methods initially used to evaluate cover crop effects on No; transport included suction probe lysimeters and measurement of NO-3; in soil samples collected to a depth of 90 cm. These measurements demonstrated extreme spatial variability in NO-3; distribution and water movement. This made it impractical to compare effects of different treatments. Soil transformations of legume and fertilizer N sources were compared using 15N labelled amendments. Less of the vetch N was found in leachable forms and, after 2 to 3 months in soil, losses of vetch N were smaller than losses of fertilizer N. To resolve the problem of spatial variability and to make direct measurements of leaching, 16 lysimeters were constructed from 55 gallon drums. These were treated with either fertilizer or legume N. Early measurements show greater NO-3; leaching with legume N, due to the mulch effect reducing evaporative water removal. However, there has been insufficient time to fully evaluate the treatments. This experiment will be continued

Determinantes de la generación de Residuos Sólidos Urbanos: El caso de los municipios de la provincia de Buenos Aires

Este trabajo tiene por objetivo estudiar los determinantes de la generación de residuos sólidos urbanos (RSU) y testear la hipótesis de la curva de Kuznets para el caso de la PBA. Se utiliza un corte transversal de la CABA y 125 municipios de la PBA. Dado que la generación de residuos es un problema con una dimensión espacial importante, se utiliza econometría espacial para considerar el posible efecto de la generación de residuos de un municipio sobre otros y se distinguen efectos directos, de indirectos y totales. Los resultados muestran una relación lineal entre la generación de RSU y el PBGpc del propio municipio. Al incorporar efectos espaciales, se observa que variaciones en el PBGpc de los municipios vecinos tienen un efecto no lineal en la generación de residuos del municipio en cuestión. La densidad poblacional tiene forma convexa y la relación entre la distancia desde el centro municipal hasta el basurero tiene forma de U invertida. Finalmente, se incorporaron tres variables dicotómicas: si el basural es a cielo abierto, si se clasifican o no los residuos y si el municipio es coordinado por CEAMSE. Las dos primeras no presentan un efecto significativo, pero la tercera sí y es negativo.Facultad de Ciencias Económica

CD8+T cells fail to limit SIV reactivation following ART withdrawal until after viral amplification

To define the contribution of CD8+ T cell responses to control of SIV reactivation during and following antiretroviral therapy (ART), we determined the effect of long-term CD8+ T cell depletion using a rhesusized anti-CD8β monoclonal antibody on barcoded SIVmac239 dynamics on stable ART and after ART cessation in rhesus macaques (RMs). Among the RMs with full CD8+ T cell depletion in both blood and tissue, there were no significant differences in the frequency of viral blips in plasma, the number of SIV RNA+ cells and the average number of RNA copies/infected cell in tissue, and levels of cell-associated SIV RNA and DNA in blood and tissue relative to control-treated RMs during ART. Upon ART cessation, both CD8+ T cell-depleted and control RMs rebounded in fewer than 12 days, with no difference in the time to viral rebound or in either the number or growth rate of rebounding SIVmac239M barcode clonotypes. However, effectively CD8+ T cell-depleted RMs showed a stable, approximately 2-log increase in post-ART plasma viremia relative to controls. These results indicate that while potent antiviral CD8+ T cell responses can develop during ART-suppressed SIV infection, these responses effectively intercept post-ART SIV rebound only after systemic viral replication, too late to limit reactivation frequency or the early spread of reactivating SIV reservoirs

Impact of alemtuzumab-mediated lymphocyte depletion on SIV reservoir establishment and persistence

Persistence of the rebound-competent viral reservoir (RCVR) within the CD4+ T cell compartment of people living with HIV remains a major barrier to HIV cure. Here, we determined the effects of the pan-lymphocyte-depleting monoclonal antibody (mAb) alemtuzumab on the RCVR in SIVmac239-infected rhesus macaques (RM) receiving antiretroviral therapy (ART). Alemtuzumab administered during chronic ART or at the time of ART initiation induced >95% depletion of circulating CD4+ T cells in peripheral blood and substantial CD4+ T cell depletion in lymph nodes. However, treatment was followed by proliferation and reconstitution of CD4+ T cells in blood, and despite ongoing ART, levels of cell-associated SIV DNA in blood and lymphoid tissues were not substantially different between alemtuzumab-treated and control RM after immune cell reconstitution, irrespective of the time of alemtuzumab treatment. Upon ART cessation, 19 of 22 alemtuzumab-treated RM and 13 of 13 controls rebounded in <28 days with no difference in the time to rebound between treatment groups. Time to rebound and reactivation rate was associated with plasma viral loads (pVLs) at time of ART initiation, suggesting lymphocyte depletion had no durable impact on the RCVR. However, 3 alemtuzumab-treated RM that had lowest levels of pre-ART viremia, failed to rebound after ART withdrawal, in contrast to controls with similar levels of SIV replication. These observations suggest that alemtuzumab therapy has little to no ability to reduce well-established RCVRs but may facilitate RCVR destabilization when pre-ART virus levels are particularly low

Site-specific seeding using multi-sensor and data fusion techniques : a review

Site-specific seeding (SSS) is a precision agricultural (PA) practice aiming at optimizing seeding rate and depth, depending on the within field variability in soil fertility and yield potential. Unlike other site-specific applications, SSS was not adopted sufficiently by farmers due to some technological and practical challenges that need to be overcome. Success of site-specific application strongly depends on the accuracy of measurement of key parameters in the system, modeling and delineation of management zone maps, accurate recommendations and finally the right choice of variable rate (VR) technologies and their integrations. The current study reviews available principles and technologies for both map-based and senor-based SSS. It covers the background of crop and soil quality indicators (SQI), various soil and crop sensor technologies and recommendation approaches of map-based and sensor-based SSS applications. It also discusses the potential of socio-economic benefits of SSS against uniform seeding. The current review proposes prospective future technology synthesis for implementation of SSS in practice. A multi-sensor data fusion system, integrating proper sensor combinations, is suggested as an essential approach for putting SSS into practice