Crystal structure and physical properties of EuPtIn4_{4} intermetallic antiferromagnet

We report the synthesis of EuPtIn$_{4}$ single crystalline platelets by the In-flux technique. This compound crystallizes in the orthorhombic Cmcm structure with lattice parameters $a=4.542(1)$ \AA, $b=16.955(2)$ \AA$\,$ and $c=7.389(1)$ \AA. Measurements of magnetic susceptibility, heat capacity, electrical resistivity, and electron spin resonance (ESR) reveal that EuPtIn$_{4}$ is a metallic Curie-Weiss paramagnet at high temperatures and presents antiferromagnetic (AFM) ordering below $T_{N}=13.3$ K. In addition, we observe a successive anomaly at $T^{*} = 12.6$ K and a spin-flop transition at $H_{c} \sim 2.5$ T applied along the $ac$-plane. In the paramagnetic state, a single Eu$^{2+}$ Dysonian ESR line with a Korringa relaxation rate of $b = 4.1(2)$ Oe/K is observed. Interestingly, even at high temperatures, both ESR linewidth and electrical resistivity reveal a similar anisotropy. We discuss a possible common microscopic origin for the observed anisotropy in these physical quantities likely associated with an anisotropic magnetic interaction between Eu$^{2+}$ 4$f$ electrons mediated by conduction electrons.Comment: 5 pages, 5 figure

Estimating the Spatial Distribution of Groundwater Demand In the Texas High Plains

Developing groundwater management plans requires a good understanding of the interdependence of groundwater hydrology and producer water use behavior. While state-of-the-art groundwater models require water demand data at highly disaggregated levels, the lack of producer water use data has held up the progress to meet that need. This paper proposes an econometric framework that links county-level crop acreage data to well-level hydrologic data to produce heterogeneous patterns of crop choice and irrigation practices within a county. Together with agronomic data on irrigation water requirements of various crops and irrigation practices, this model permits estimation of the water demand distribution within a county. We apply this model to a panel of 16 counties in the Southern Texas High Plains from 1972 to 2000. The results obtained not only are consistent with those from the traditional multinomial logit land use model, but also indicate the presence of large intra- and inter-county heterogeneity in producer water use behavior.Discrete Choice Model, Random-coefficients Discrete Choice Model, Crop Choice, BLP, Groundwater, Texas High Plains, Ogallala Aquifer, Crop Production/Industries, Resource /Energy Economics and Policy,

Ionospheric response to the 2009 sudden stratospheric warming over the equatorial, low, and middle latitudes in the South American sector

The present study investigates the ionospheric total electron content (TEC) and F-layer response in the Southern Hemisphere equatorial, low, and middle latitudes due to major sudden stratospheric warming (SSW) event, which took place during January-February 2009 in the Northern Hemisphere. In this study, using 17 ground-based dual frequency GPS stations and two ionosonde stations spanning latitudes from 2.8°N to 53.8°S, longitudes from 36.7°W to 67.8°W over the South American sector, it is observed that the ionosphere was significantly disturbed by the SSW event from the equator to the midlatitudes. During day of year 26 and 27 at 14:00 UT, the TEC was two times larger than that observed during average quiet days. The vertical TEC at all 17 GPS and two ionosonde stations shows significant deviations lasting for several days after the SSW temperature peak. Using one GPS station located at Rio Grande (53.8°S, 67.8°W, midlatitude South America sector), it is reported for the first time that the midlatitude in the Southern Hemisphere was disturbed by the SSW event in the Northern Hemisphere.Fil: Fagundes, P. R.. Universidade do Vale do Paraíba; BrasilFil: Goncharenko, L. P.. Massachusetts Institute of Technology; Estados UnidosFil: De Abreu, A. J.. Universidade do Vale do Paraíba; BrasilFil: Venkatesh, K.. Universidade do Vale do Paraíba; BrasilFil: Pezzopane, M.. Istituto Nazionale Di Geofisica E Vulcanologia; ItaliaFil: De Jesus, R.. Universidade do Vale do Paraíba; BrasilFil: Gende, Mauricio Alfredo. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Coster, A. J.. Massachusetts Institute of Technology; Estados UnidosFil: Pillat, V. G.. Universidade do Vale do Paraíba; Brasi

Impact evaluation of the Vila Viçosa small hydroelectric power plant (Portugal) on the water quality and on the dynamics of the benthic macroinvertebrate communities of the Ardena river

Over a two-year period a study of the Vila Viçosa small hydroelectric development, located on the Ardena river (hydrographical basin of the Douro river, Portugal), was conducted, with the objective of evaluating the impact of its operation on the water quality and on the dynamics of the benthic macroinvertebrate community. A morphological, hydrologic and physico-chemical characterization of the system was done, an analysis of the benthic macroinvertebrate communities looking into their structure and dynamics, as well as ecological and physiological characteristics. With the physical and chemical data, a study of its spatial and temporal variation was performed. With the data related to the macroinvertebrate communities, an analysis of the spatial variation of some indexes and metrics and of the (non) similarity between the samples collected were done, bearing in mind the composition of the communities, through different techniques of multivariate analysis. After the analysis of the data, it is possible to say that the Ardena River is a lothic system, with good water quality, in which the working of the small hydroelectric power plant causes alterations on the macroinvertebrate community, due to the alteration of the "natural" hydrologic regime. The impact on the macroinvertebrate communities is lower upstream of the plant, where the flow is minimal throughout the whole year leading to a change in the structure of the community. Downstream of the plant, where the flow is extremely variable, there is an impoverishment of the communities, leading to the displacement of substrate and organisms.Durante dos años se ha estudiado la minicentral hidroeléctrica de Vila Viçosa en el río Ardena (cuenca del Duero, Portugal), con el objetivo de evaluar el impacto de su funcionamiento en la calidad del agua y en la dinámica de la comunidad de macroinvertebrados bentónicos, haciendo la caracterización del sistema desde el punto de vista morfológico, hidrológico y físico-químico y estudiando las comunidades de macroinvertebrados bentónicos, atendiendo a aspectos relacionados con su estructura, dinámica y características ecológicas y fisiológicas. Con los datos relativos a los parámetros físico-químicos se ha hecho el estudio de la variación espacio temporal; y con los datos relativos a la comunidad de macroinvertebrados, se ha hecho el estudio de la variación espacial de algunos índices y medidas y de la (dis)similaridad entre las muestras recogidas, teniendo en cuenta su composición, a través de diferentes técnicas de análisis multivariante. Después de analizados los datos, se puede decir que el río Ardena es un sistema lotico con agua de buena calidad y que el funcionamiento de la minicentral hidroeléctrica provoca modificaciones en la comunidad de macroinvertebrados bentónicos, resultado de las alteraciones de caudales. El impacto en las comunidades de macroinvertebrados es menor aguas arriba de las minicentrales, donde el caudal es mínimo todo el año provocando una modificación en la estructura de las comunidades. Aguas abajo de las minicentrales, donde el caudal es muy variable, hay un empobrecimiento de las comunidades, provocando el desplazamiento del substrato y de los organismos

Monitoramento fenológico do açaí-do-amazonas (Euterpe precatoria Mart.) nas condições de Belém, PA.

Euterpe precatoria Mart vulgarmente conhecida como açaí-do-amazonas, açaí-solitário e juçara é uma das espécies de açaizeiro nativa da Amazônia, com forte ocorrência na parte ocidental, mas que vem sendo cultivada no Pará por apresentar características agronômicas desejáveis ao mercado de polpa. Estudos fenológicos dessa palmeira são escassos, apesar de fundamentais na gestão de plantios em escala comercial. O objetivo deste trabalho foi avaliar aspectos fenológicos de floração e de frutificação do açaí-do-amazonas nas condições de Belém, PA. Foram avaliadas, mensalmente, 37 plantas da espécie em foco em plena fase reprodutiva, no período de janeiro a dezembro de 2013 para três características de floração e três de frutificação. Os dados obtidos foram expressos em número, sendo calculada a média de ocorrência de cada evento. No período avaliado foi detectado que tanto a floração quanto a frutificação apresentaram irregularidades no ciclo