High Valley Research Articles

Origen, localización y evolución de los «panares» del municipio de Gistaín

The aim of this paper is to study an agricultural system typical of the Pyrenean area, based on the example of Gistaín, a municipality located in a high valley of the Aragonese Pyrenees. In this enclave, the panar system endured until the 1980s, while in other valleys it disappeared much earlier. First, the panar model is approached from a general perspective using the limited literature available on the subject. The focus then shifts to the study area and the Gistaín municipality is analysed in its mid-nineteenth-century configuration, based on three fundamental sources: a field study of the land, oral tradition collected from the older inhabitants and documentary records, mainly the amillaramiento of 1863. Some older documents, mainly from the sixteenth and seventeenth centuries, were also consulted in the Municipal Archive. In the conclusions, some ideas are provided about the origin and evolution of these spaces.

Monte Carlo fingerprinting of the terrestrial sources of different particle size fractions of coastal sediment deposits using geochemical tracers: some lessons for the user community.

A sediment source fingerprinting method, including a Monte Carlo simulation framework, was used to quantify the contributions of terrestrial sources of fine- (< 63μm) and coarse-grained (63-500μm) sediments sampled from three categories of coastal sediment deposits in the Jagin catchment, south-east of Jask, Hormozgan province, southern Iran: coastal dunes (CD), terrestrial sand dunes or onshore sediments (TSD), and marine or offshore sediments (MD). Forty-nine geochemical properties were measured in the two size fractions and a three-stage statistical process consisting of a conservation test, the Kruskal-Wallis H test, and stepwise discriminant function analysis (DFA) was applied to select final composite fingerprints for terrestrial source discrimination. Based on the statistical tests, four final fingerprints comprising Be, Ni, K and Cu and seven final fingerprints consisting Cu, Th, Be, Al, La, Mg and Fe were selected for discriminating terrestrial sources of the coastal fine- and coarse-grained sediments, respectively. Two geological spatial sources, including Quaternary (clay flat, high and low level fans and valley terraces) and Palaeocene age deposits, were identified as the main terrestrial sources of the fine-grained sediment sampled from the coastal deposits. A geological spatial source consisting of sandstone with siltstone, mudstone and minor conglomerate (Palaeocene age deposits) was identified as the main terrestrial source for coarse-grained sediment sampled from the coastal deposits.

Dark-exciton valley dynamics in transition metal dichalcogenide alloy monolayers

We report a comprehensive theory to describe exciton and biexciton valley dynamics in monolayer Mo1−xWxSe2 alloys. To probe the impact of different excitonic channels, including bright and dark excitons, intravalley biexcitons, intervalley scattering between bright excitons, as well as bright biexcitons, we have performed a systematic study from the simplest system to the most complex one. In contrast to the binary WSe2 monolayer with weak photoluminescence (PL) and high valley polarization at low temperatures and the MoSe2, that presents high PL intensity, but low valley polarization, our results demonstrate that it is possible to set up a ternary alloy with intermediate W-concentration that holds simultaneously a considerably robust light emission and an efficient optical orientation of the valley pseudospin. We find the critical value of W-concentration, xc, that turns alloys from bright to darkish. The dependence of the PL intensity on temperature shows three regimes: while bright monolayer alloys display a usual temperature dependence in which the intensity decreases with rising temperature, the darkish alloys exhibit the opposite behavior, and the alloys with x around xc show a non-monotonic temperature response. Remarkably, we observe that the biexciton enhances significantly the stability of the exciton emission against fluctuations of W-concentration for bright alloys. Our findings pave the way for developing high-performance valleytronic and photo-emitting devices.

Fate of pioneering vegetation patches in a dynamic meandering river

AbstractFluvial biomorphodynamics in actively meandering rivers entail interactions between hydromorphodynamics and pioneering tree species that have eco‐engineering effects. Here we study spatiotemporal patterns of vegetation patches smaller than 150 m2 in a 4 km reach of the river Allier in France in order to unravel causes for tree persistence and mortality and identify spatial trends across the river valley. To this end we analysed aerial photographs by object‐based image analysis over a period of 56 years and tracked individual patches through time. Furthermore the cover and surface age of the study reach were classified. The large‐scale shifts of channels, bars and vegetation are consistent with the meandering process and chute cutoffs. However, the spatiotemporal patterns of the vegetation patches are surprising in that they are ubiquitous and have ages up to decades on the highly dynamic meander belt, but hardly expand into larger vegetation patches. Patches disappear exponentially as a function of their age, and faster so in the last decades. Causes are amalgamation into the riparian forest flanking the meander belt and mortality likely due to desiccation or erosion. Patches have a higher probability of survival when further away from the active channel and closer to high vegetation patches and valley boundary. The window of opportunity of vegetation settlement widens towards the valley boundaries and in floodplain lows of former channels and chutes. These results imply a gradual cross‐valley gradient of riparian vegetation settling, survival and succession. © 2019 The Authors. Earth Surface Processes and Landforms Published by John Wiley &amp; Sons Ltd.

Danger along the high road: report from the 2017 field season of the Vayots Dzor Fortress Landscapes Project (VDFLP), Armenia

The Vayots Dzor Fortress Lansdscapes Project investigates the rise and fall of fortress culture in southern Armenia, focusing on the Late Bronze/Early Iron and medieval periods. The paper summarises the findings of the inaugural field season in 2017. The team performed extensive and intensive survey in a high alpine valley that was a key transportation corridor between Lake Sevan in the north and Nakhichevan and northwest Iran to the south. The project employed digital mapping, drone photogrammetry and digital storytelling in support of digital humanities approaches. Important findings include the documentation of Late Bronze/Early Iron cyclopean fortress architecture situated along roads as well as evidence for Urartian control of the valley. Furthermore, medieval structures and monuments are prominent features in the archaeological record of the valley.

基于生态系统服务价值损益的生态安全格局演变分析——以辽宁沿海瓦房店市为例

PDF HTML阅读 XML下载 导出引用 引用提醒 基于生态系统服务价值损益的生态安全格局演变分析——以辽宁沿海瓦房店市为例 DOI: 10.5846/stxb201809071916 作者: 作者单位: 辽宁师范大学海洋经济与可持续发展研究中心,辽宁师范大学城市与环境学院,辽宁师范大学海洋经济与可持续发展研究中心,辽宁师范大学海洋经济与可持续发展研究中心,辽宁师范大学城市与环境学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41571122）；辽宁省教育厅项目（H201783631，WQ2019020）；辽宁省自然科学基金（20180551194）；辽宁省社会科学规划基金项目（L17CJY003）；辽宁省社科联2019经济社会发展立项项目（2019lslktjd-014）；辽宁师范大学校博士启动（BS2018L007） The evolution of ecological security pattern based on the profit and loss analysis of ecosystem services: taking Wafangdian County as a case Author: Affiliation: Center for Studies of Marine Economy and Sustainable Development of Liaoning Normal University,,Center for Studies of Marine Economy and Sustainable Development of Liaoning Normal University,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:生态系统服务是区域生态安全的底线，科学评估其价值变化是合理规划区域土地利用和构建生态安全格局的重要基础，既有研究尚未综合评估多种生态系统服务来判定区域生态基底，目前开展的静态评价也难以反映区域生态安全格局动态变化过程。以辽宁沿海地区——瓦房店市为例，综合运用CASA、RUSLE等模型，并结合生态经济法对2000年和2014年生态系统服务价值进行了科学评估，并依据评估结果构建研究区两期生态安全格局。结果表明：①14年间，除营养物质循环变化不明显外，其余各项生态系统服务价值均呈现不同幅度的损失，其中以水源涵养价值下降趋势最为明显。各土地利用类型来看，林地生态系统服务价值损失达8.74亿元，占损失总量的40%，为各地类之首；②两期单位面积生态系统服务价值均呈现出水域（含海域）高于陆地，山地高于平地的空间分布，且这种不均匀分布趋势在2014年更为明显；③两期生态源地面积分别为1111.40 km2和356.96 km2，生态廊道总长度分别为136.63 km和231.43 km，呈环状分布于源地之间的生态系统服务价值高值谷内。生态系统服务价值的损益情况可对区域生态安全格局构建产生重要影响，研究结果可为瓦房店市城市开发边界与生态保护红线划定提供科学参考。 Abstract:Ecosystem services are the baseline of regional ecological security. Scientific assessment of their value changes is a basis for rationally planning of the regional land use and constructing ecological security pattern. The existing studies did not comprehensively evaluate various ecosystem services to determine regional ecological basements. The current static assessments failed to reflect the dynamic process of regional ecological security patterns. Hence, using CASA, RUSLE, and other models, as well as the ecological economic method, we evaluated the ecosystem service value in Wafangdian County, Liaoning coastal area in 2000-2014. Then, the two-stage ecological security pattern was constructed based on the scientific assessment. The results are as follows:①during the 14 years, except for the inconspicuous change of nutrient recycling value, the other ecosystem service values have showed different degrees of loss, especially for water source conservation value with the worst decline of 44%. In terms of land use type, the value of forestland ecosystem services lost 874 million Yuan, up to 40% of the total loss. ② For the ecosystem services per unit value of the study area in the two periods, water area (including sea) was higher than land, but mountain was higher than flatlands. This uneven spatial distribution was more obvious in 2014. ③ The ecological source areas in 2000 and 2014 were 1111.40 km2 and 356.96 km2, respectively. The total length of the corridors were 136.63 km and 231.43 km. The ring-like corridors were distributed in the high value valley of ecosystem service value among the source areas. The profit and loss of ecosystem service value have an impact on the construction of the regional ecological security pattern. The results can provide a scientific guideline for the delineation of urban development boundary and ecological protection red line in Wafangdian. 参考文献 相似文献 引证文献

Distribución espacial y estructura de la población de &lt;i&gt;Pitcairnia huilensis&lt;/i&gt; (Bromeliaceae) en el valle alto del río Magdalena (Huila, Colombia

Se estudió el patrón de distribución espacial y la estructura de la población de Pitcairnia huilensis (Bromeliaceae), una especie considerada en Peligro Crítico (CR), del valle alto del río Magdalena en los Andes colombianos. La distribución espacial se determinó con la función K de Ripley. Para conocer la estructura poblacional se establecieron cuatro categorías de tamaño: plántulas, juveniles, subadultos y adultos, las cuales fueron caracterizadas estadísticamente por medio de variables morfométricas. Con el fin de saber cuál de las variables morfométricas presentaba mayor variabilidad se usó un Análisis de Componentes Principales. Para examinar si había diferencias significativas entre las variables morfométricas por categorías de tamaño con mayor variabilidad (altura total) se realizó una prueba de Kruskal Wallis y para identificar cuáles eran las diferencias de las categorías de tamaño con respecto a esta variable se aplicó una prueba de Tukey. Adicionalmente, para determinar si había dependencia entre el peso seco y la altura total se realizó una regresión lineal. Se encontraron 289 parches de P. huilensis que mostraron un patrón de distribución espacial agregado. La densidad de individuos por m2 varía entre 0,1 y 3,9. Hubo diferencias significativas entre las variables morfométricas, siendo la altura total la que mejor explica la variación y la que más se relaciona con el peso seco total. Con este trabajo se señala la importancia de los resultados para el manejo y la conservación de P. huilensis en el área de estudio.

Piemonte. Tra stasi e sperimentazioni, un quadro chiaroscurale / Piedmont. Between stasis and experimentations, a «chiaroscuro» framework

The contemporary architectural production in the Alps of Piedmont has to be studied taking into consideration the contrasting phenomena of depopulation and tourism that have involved the mountain areas of the region during last century. In the fifties and sixties the percentage of abandonment of the high valleys reaches even 80-90%. Entire communities move to industrial urban centers in the cities on the plain. On the other side we witness to a strong polarization of the winter stations that become real “banlieues blanches” for the free time of the citizens and where the architecture of alpine modernism, with various forms, shapes. The paradox nowadays is that the rarefaction of abandoned and depopulated territories is necessary to force to start and choose new innovative paths. We witness a contemporary situation with different shades: on one side the well-established touristic territories that need projects to promote the redevelopment and diversification, on the other side the marginal places where are rising new visions are practices of reactivation of the territory in which architecture is fundamental. The topic of quality of the construction of the physical space intersects with the regeneration of places on a cultural basis, new agriculture and green economy, innovative development of the patrimony, sustainable tourism, with inclusive and participative paths of nature, by giving new meanings to places and building new economies and identities.

Rendimiento de híbridos de maíz grano blanco en cinco localidades de Valles Altos de México

Dada la insuficiencia en producción de maíz, que se traduce en la importación de hasta 15 millones de toneladas de grano, urge elevar la productividad en este cultivo, utilizando más y mejores variedades. El objetivo de este trabajo fue determinar las características agronómicas de híbridos blancos en cinco ambientes diferentes, la respuesta mejor, así como definir el efecto de la interacción genotipo × ambiente sobre el rendimiento, y otras características evaluadas para los Valles Altos de México (2 200 a 2 600 msnm). En el ciclo agrícola primavera-verano 2016, se evaluaron diez híbridos de maíz en cinco localidades mediante un diseño experimental de bloques completos al azar, con cuatro repeticiones. El análisis fue factorial considerando como factores los ambientes (5), los híbridos (10), así como la interacción ambiente × híbridos. Se evaluaron ocho variables agronómicas. Se realizaron Anovas y comparaciones de medias Tukey p= 0.05. Ambos factores presentaron respuestas diferenciales y las variables evaluadas estuvieron influenciadas por el efecto del ambiente. Los híbridos de productividad media mayor fueron ATZIRI PUMA (12 t ha-1) y TSIRI PUMA (11.8 t ha-1) seguidos por los híbridos H-50, H-66 y H-70, que produjeron 11.5, 11.6 y 11.6 t ha-1 respectivamente. Considerando que H-50 es uno de los híbridos de mayor uso comercial en los Valles Altos, los cuatro híbridos referidos de mayor rendimiento de grano blanco, podrían tener perspectivas de uso comercial, en los ambientes manejados en este estudio.

Progressive sensitivity of trophic levels to warming underlies an elevational gradient in ant–aphid mutualism strength

Although species interactions are often proposed to be stronger at lower latitudes and elevations, few studies have evaluated the mechanisms driving such patterns. In this study, we assessed whether, and by which mechanisms, abiotic changes associated with elevation altered the outcome of an ant–aphid protection mutualism. To do so, we characterized the multi‐trophic interactions among the ant Formica podzolica, the aphid Aphis varians, and aphid natural enemies occurring on the plant Chamerion angustifolium within replicate high and low elevation valleys. Low (versus high) elevation sites had longer summers (snowmelt 13 days earlier) and were on average 1.1°C warmer and 41% drier throughout the year. At low elevations, individual ant colonies consumed approximately double the volume of carbohydrate baits, likely due to a higher foraging tempo, and possibly due to a greater demand for sugar‐ versus protein‐rich resources (as indicated by stable isotope analysis). Wild aphid colonies at low elevations were visited by 1.4‐fold more natural enemies (controlling for variation in aphid abundance), while experimental aphid colonies on potted plants were tended 52% more frequently by ants. As a result, ants increased aphid colony survival by 66% at low elevations but had no detectable effect at high elevations; at low (versus high) elevations aphid colonies without ants had lower survival, demonstrating stronger predator effects, while aphid colonies with ants had higher survival, demonstrating even stronger ant benefits. Analyses for the effects of mean summer temperature yielded qualitatively identical results to those based on elevation. Collectively, these findings support predictions for a greater sensitivity of higher trophic levels to warming and demonstrate how species interactions can vary across environmental gradients due to simultaneous changes in species traits and abundances across multiple trophic levels.

Isotopic Characteristics and Water Interaction of Ifni Lake and Spring of Tifnoute Valley (High Atlas Mountains, Morocco, North of Africa)

Geochemical and isotopic investigations were carried out to indicate the interaction process between Ifni Lake water and high valley of Tifnoute springs. A total of 18 water samples were collected and analyzed. The Ifni Lake constitutes a veritable water resource in the study area, and this water can be the origin of alimentation the springs located in the high valley the Tifnoute. This study aims to improve the interaction between Ifni Lake water and the springs of high valley of Tifnoute. It is mainly focused to identify the origin of groundwater recharge and mineralization. The environmental isotope (deuterium (δ2H) and oxygen-18 (δ18O)) measurements allowed understanding the hydro geochemical process, the origin of the mineralization of the water. Also the results identify the relationship between the waters of Ifni Lake and the spring's water of high valley of Tifnoute. The isotopic compositions reveal that the origin of Ifni Lake water is meteoric, and the water infiltrates directly in the groundwater without any evaporation.

Development and Assessment of Localized Seasonal Rainfall Prediction Models: Mapping and Characterizing Rift Valley Fever Hotspot Areas in the Southern and Southeastern Ethiopia

Rift Valley Fever disease has been recognized as being among permanent threats for the sustainability of livestock production in Ethiopia, owing to shared boarders with RVF endemic countries in East Africa. Above-normal and widespread rainfall have outweighed as immediate risk factor that facilitated historical outbreaks of the disease in the East Africa. The objective of the present study, thus, was to develop prospective localized seasonal rainfall anomaly prediction models, and assess their skills as early indicators to map high risk localized rift valley fever disease outbreak areas (hotspots) over the southern and southeastern part of Ethiopia. 21 years of daily rainfall data; for five meteorological stations, was employed in diagnosing existences of any anomalous patterns of rainfall, along with a cumulative rainfall analysis to determine if there were ideal conditions for potential flooding. The results indicated that rainfall in the region is highly variable; with non-significant trends, and attributed to be the results of the effects of large-scale climatic-teleconnection. The moderate to strong positive correlations found between the regional average rainfall and large scale teleconnection variables (r &amp;ge; 0.48), indicated some potentials for early prediction of seasonal patterns of rainfall. Accordingly, models developed, based on the regional average rainfall and emerging developments of El Ni&amp;ntilde;o/Southern Oscillation and other regional climate forcings, showed maximum skills (ROC scores &amp;ge; 0.7) and moderate reliability. Deterministically, most of the positive rainfall anomaly patterns, corresponding to El Ni&amp;ntilde;o years, were portrayed with some skills. The study demonstrated that localized climate prediction models are invaluable as early indicators to skillfully map climatically potential RVF hotspot areas.

Gacela H72: híbrido de maíz precoz para áreas de temporal y riego del Altiplano Central de México

Debido al cambio climático que se manifiesta en distribución irregular de la precipitación pluvial menor cantidad de ésta o su incidencia en temporal retrasado y mayor temperatura, surge el problema de falta de híbridos de maíz precoz sobre todo para regiones de bajo y mediano potencial productivo de la mesa central de México, las cuales cubren 1 200 000 ha de la superficie cultivada. El híbrido de maíz precoz Gacela H72, se generó para responder a esas condiciones del cambio climático, ya que es un híbrido doble de ciclo precoz y gran rusticidad, presenta crecimiento y desarrollo vigoroso en la etapa vegetativa inicial, por lo cual supera en porte de planta a otros híbridos de maíz durante los 30 días después de la emergencia, es tolerante a la sequía en etapa vegetativa y reproductiva y rinde bien en condiciones de baja fertilización química. Su rendimiento tiene un rango de 3 a 11 t ha-1 el cual supera a las variedades criollas 50% y a híbridos comerciales privados 20%. Presenta su periodo a espigamiento entre los 95 y 100 días a altitudes de 2 600 m donde otros híbridos y variedades lo alcanzan a 110 y 115 días. Es resistente al carbón de la espiga (Sphaceloteca reiliana) y a la pudrición de la mazorca (Fusarium spp.) y tiene calidad nixtamalera-tortillera. Gacela H72, por ser híbrido doble, posee progenitores de mayor productividad en semilla que otros híbridos, su progenitor hembra rinde 7.5 t ha-1 en Valles Altos, lo cual concede 25% más rentabilidad en la producción de semilla registrada y certificada respecto a otros híbridos. Su porte de planta facilita la siembra intensiva con 70 000 plantas ha-1 y con siembra a doble hilera a 100 000 plantas ha-1 se logran rendimientos de 10 a 11 t ha-1. La cosecha se realiza a 150 días con una humedad en grano de 25%, por lo que la mazorca debe someterse a un proceso de secado (14% humedad). En áreas de riego y buen temporal tiene potencial para la producción de forraje. El principal impacto económico del Gacela H72 es la diferencia de 3 a 4 t ha-1 sobre el rendimiento de la variedad criolla, lo cual representa de 12 000.00 a 16 000.00 pesos ha-1, lo que hace rentable la producción de maíz.

Control químico de la roya lineal en diferentes etapas de desarrollo del trigo en Terrenate, Tlaxcala

&#x0D; &#x0D; &#x0D; En México la principal zona productora de trigo de temporal está ubicada en los Valles Altos del Centro de México, donde la roya lineal (Puccinia striiformis f. sp. tritici Eriks) se ha convertido en el principal problema en los últimos años, siendo mucho más agresiva que la roya de la hoja (Puccinia triticina Eriks). Con el propósito de conocer la etapa más apropiada para la aplicación de fungicidas para el control de la enfermedad, se utilizaron cuatro formulaciones comerciales y diferentes estrategias de protección, buscando ampliar el conocimiento en el control de la roya lineal en variedades susceptibles y así mejorar la producción del trigo harinero en condiciones de temporal. La presente investigación se llevó a cabo durante el ciclo primavera-verano, 2015 utilizando la variedad Nana F2007 en el municipio de Terrenate, Tlaxcala, México. La mejor estrategia de protección fue la 2, que corresponde a la aplicación de fungicidas sistémicos a los 45 días después de la siembra (dds) y en antesis (70 dds), que se asoció con el mayor rendimiento. Los fungicidas que presentaron el mejor control sobre la roya lineal fueron la mezcla de Axozistrobina+Propiconazole (QUILT®) y Tebuconazole (Folicur 250EW), con los que se obtuvieron los valores más altos de rendimiento y efectos estadísticamente semejantes. Los resultados indican que es necesario realizar la aplicación de fungicidas para el control de la enfermedad, de lo contrario las pérdidas en rendimientos podrían ser de 53% entre estrategias y hasta 84% sin aplicación de fungicida.&#x0D; &#x0D; &#x0D;

Spin- and valley-dependent negative magnetoresistance in a ferromagnetic MoS2 junction with a quantum well

We studied the spin and valley transports and magnetoresistance effect in a ${\mathrm{MoS}}_{2}$ junction with a quantum well inserted between the gate voltage and the ferromagnetic ${\mathrm{MoS}}_{2}$, which can apply generally to other transition metal dichalcogenides with the same crystal structure. In the absence of a quantum well, the broken inversion symmetry and spin-orbit coupling for ${\mathrm{MoS}}_{2}$ could give rise to a fully spin- and valley-polarized conductance for the parallel configuration, while there is no spin and valley polarization for the antiparallel configuration. The general condition of pure polarization and the position of resonant conductance are achieved. The magnetoresistance is positive and oscillates with the gate voltage. Dramatically, the presence of a quantum well can lead to the formation of spin-polarized quantum well states. As a result, the conductances for opposite spin and valley indices have a steady phase shift, making them oscillate in antiphase with the well width. Therefore, the high spin and valley polarization could be obtained for the antiparallel and parallel configurations. In particular, the spin-polarized quantum well states directly result in negative polarization and negative magnetoresistance.

Enumerations of peaks and valleys on non-decreasing Dyck paths

A valley in a Dyck path is a local minimum, and a peak is a local maximum. A Dyck path is non-decreasing if the y-coordinates of the valleys of the path valley form anon-decreasing sequence. In this paper we provide some statistics about peaks and valleys in non-decreasing Dyck paths, such as their total number, the number of low and high valleys, low and high peaks, etc. Our methods include bijective proofs, recursive relations, and the symbolic method for generating functions.

Precios, salarios y carga laboral durante el siglo xviii. El caso de la villa de El Burgo de Osma (Soria)

This article provides new evidence regarding the evolution of prices and wages in the eighteenth century. Unlike most of the works so far available, this focuses on a small population core, the episcopal town of El Burgo de Osma (Soria), located in an area also lesser studied, the high valley of the Duero. The local price index describes the same trends and cycles as those of other larger population. On the other hand, an analysis of the relationship between real wages and the workload indicates that in the course of the eighteenth century there was a remarkable increase in work.

Áreas para producción de semilla de trigo en Valles Altos Centrales de México

La zonificación agro-ecológica permitió definir localidades con aptitud para el establecimiento del cultivo de trigo, así como las áreas que presentan condiciones no favorables para el desarrollo de la enfermedad tizón de la espiga por Fusarium sp. (TEF) la cual ocasiona reducción del peso en los granos y contaminación por micotoxinas, entre las que se encuentra el deoxinivalenol (DON). En general, la producción agrícola es determinada por las combinaciones de clima y suelo. Para el trigo se consideró como temperatura optima 15 a 23 °C, precipitación 750 a 900 mm, y altitud 4 500 msnm, TEF depende principalmente de la interacción de los factores climáticos y genotipo. Los umbrales climáticos considerados fueron los reportados para intensificar el índice relativo de la enfermedad: temperatura mínima mayor de 11 ºC, temperatura media mayor de 16.5 ºC, oscilación térmica menor a 13.4 ºC y precipitación pluvial mayor de 30 mm. Se delimitaron geográfica y cuantitativamente áreas potenciales considerando los criterios que definen lugares y superficies climáticamente aptas para el cultivo del trigo de temporal (mayo a octubre) y no aptas para la TEF haciendo una discriminación de las zonas urbanas y de otro uso que no sea el agrícola, por lo tanto el mapa generado se puede utilizar como herramienta de planeación para el establecimiento del cultivo del trigo, extensión de áreas y renovación de plantaciones para la producción de semilla en los Valles Altos Centrales de México.

Hydrochemical characteristics and quality assessment of groundwater for irrigation use in central and eastern Songnen Plain, Northeast China

The hydrochemical characteristics of groundwater in Songnen Plain's agricultural area were analyzed based on aquifer types and topography classification to evaluate irrigation suitability and factors influencing groundwater quality. Samples of different groundwater types and topographical conditions within the research area were collected and chemical indices, such as sodium adsorption ratio, %Na+, residual sodium carbonate, and magnesium hazard values, were calculated to assess the groundwater suitability for irrigation. The results indicated that groundwater was generally neutral, with low total dissolved solids and slightly high hardness; the dominant anion in groundwater was HCO3-, while Ca2+ was the relatively stable primary cation found in water samples from the high plain and river valley plain. The nitrate in groundwater significantly exceeded WHO drinking water standards, especially in the unconfined water of the high plain, which was due to the large-scale agricultural production activities in the eastern regions. The main reactions in the groundwater system were weathering and dissolution of carbonates and sulfates and ion-exchange reactions. Horizontal zoning in water chemical characteristics was prominent; from the high plain to river valley plain and low plain, the hydrochemistry gradually transitioned from HCO3-Ca-Na to HCO3-Na-Ca and HCO3-Na. Based on the chemical indices, the majority of samples were suitable for agricultural irrigation except for some in the western area with high salinity and sodium hazards. Treatment measures to groundwater and soil should be taken to reduce the possibility of soil salinization and promote crop growth in these latter regions.

Improvement of Thermoelectricity Through Magnetic Interactions in Layered Cr2Ge2Te6

The magnetism is proposed as a way to improve thermoelectricity, which may overcome the tradeoff between electrical conductivity and Seebeck coefficient. The correlation between magnetic configurations and thermoelectricity in layered magnetic semiconductor Cr2Ge2Te6 has been investigated using first‐principles calculations, combined with semi‐classical Boltzmann theory. The electronic structures and relevant transport properties for paramagnetic phase have been stimulated. Special quasi‐random structure (SQS) is employed to simulate electronic properties of paramagnetic state corresponding to spin‐disordered configurations. The temperature dependence of calculated Seebeck coefficient, electrical conductivity, and the figure of merit ZT is in good agreement with experimental values for paramagnetic phase. For p‐type Cr2Ge2Te6, the maximum ZT can reach 0.54 at 830 K and the carrier concentration a value of 2.1 × 1020 cm−3. The calculated figure of merit can further increase by 42% compared to the maximum experimental result by optimized doping level. Cr2Ge2Te6 without spin polarization shows a metal electric band structure, which deviates from the semiconductor of truth. This means that magnetic interactions play an important role in electronic structure and result in an excellent thermoelectricity of paramagnetic Cr2Ge2Te6. High band valley degeneracy, flat valence bands, and the localized partial density of states (PDOS) of magnetic atoms near Fermi surface induce a large Seebeck coefficient, meanwhile a good electrical conductivity is maintained in this magnetic semiconductor with high symmetry.