Geography of Talent in China During 2000–2015: An Eigenvector Spatial Filtering Negative Binomial Approach

The increase in China's skilled labor force has drawn much attention from policymakers, national and international firms and media. Understanding how educated talent locates and re-locates across the country can guide future policy discussions of equality, firm localization and service allocation. Prior studies have tended to adopt a static cross-national approach providing valuable insights into the relative importance of economic and amenity differentials driving the distribution of talent in China. Yet, few adopt longitudinal analysis to examine the temporal dynamics in the stregnth of existing associations. Recently released official statistical data now enables space-time analysis of the geographic distribution of talent and its determinants in China. Using four-year city-level data from national population censuses and 1% population sample surveys conducted every five years between 2000 and 2015, we examine the spatial patterns of talent across Chinese cities and their underpinning drivers evolve over time. Results reveal that the spatial distribution of talent in China is persistently unequal and spatially concentrated between 2000 and 2015. It also shows gradually strengthened and significantly positive spatial autocorrelation in the distribution of talent. An eigenvector spatial filtering negative binomial panel is employed to model the spatial determinants of talent distribution. Results indicate the influences of both economic opportunities and urban amenities,particularly urban public services and greening rate, on the distribution of talent. These results highlight that urban economic-and amenity-related factors have simultaneously driven China's talent's settlement patterns over the first fifteen years of the 21 st century.     

Fetkin-hydro,a new thermo-hydrological algorithm for low-temperature thermochronological modeling

Despite two decades of major advances in the field of thermochronological modeling, state-of-the-art numerical implementations still rely mostly on burial and exhumation processes to explain radiometric measurements.Even though such an approach has proved valuable, failing to account for other first-order geological variables has led to misinterpretations and therefore, calls for a refinement.In this study a new version of the Fetkin(finite element temperature kinematics, Ecopetrol) program is presented.Its new algorithm couples time-dependent hydrological and thermal calculations, thus rendering thermochronological ages that, instead of being solely dependent on the kinematical evolution of a system, conditioning by the fluid flow is also present.In contrast with previous thermochronological models, this work considers the influence of effective stress on rock properties(porosity and permeability) and therefore, in thermal conductivity.Sensitivity analyses addressing relevant geological questions show not only the versatility of the code but also, new perspectives on forward low-temperature thermochronological modeling.Groundwater circulation through pure-sandstone settings produce colder thermal architectures than those obtained in impermeable domains.Differences in cooling ages from models with and without fluid circulation are up to 5 Myr.A 4-fold variation in thrusting rates(0.5 km/Myr to 2 km/Myr) produces a 15-Myr difference in cooling ages in models with fluid flow, which contrasts to much lower differences, only 2 Myr, in domains without(or minimal) fluid circulation.2D thermal solutions in fold-bend-fold thrust belts composed of sandstones remain static despite substantial relief development by kinematic folding.A case-study from Western Argentina, in the Andean Precordillera, confirms the plausibility of the numerical algorithm here posed and raises new questions on the first-order thermal controls in settings under deformation.     

Fish assemblage structure on sandy beaches with different anthropogenic influences and proximity of spawning grounds

Fish assemblages in an insular (preserved) and a continental (disturbed) sandy beach were compared to assess any changes that could be attributed to anthropogenic influences and/or the proximity of the fish spawning grounds. We expected that the closer geographical position to the spawning grounds and the small amount of anthropogenic disturbance on the insular beach would be likely to provide more suitable conditions for early fish development compared with the continental beach. A total of 192 samples (96 in each beach) were taken, yielding 68 fish species, mostly young‐of‐the‐year. Fish assemblage structure differed significantly between the two beaches. Moreover, the insular beach had higher number of species, number of individuals and biomass compared with the continental beach. The commercially important Clupeiformes Harengula clupeola, Anchoa tricolor and Anchoa januaria, Perciformes Micropogonias furnieri and Mugiliformes Mugil liza were typical species on the insular beach, partitioning the seasonal use of the beach. On the other hand, a few abundant non‐commercial species, mainly the Atheriniformes Atherinella brasiliensis and the Perciformes Eucinostomus argenteus and Diapterus rhombeus, occurred all year round at the continental beach. The high fish richness and abundance and the more conspicuous species turnover across seasons on the insular beach are probable indications of more complex and dynamic organization of the communities favored by better geographical position and less anthropogenic disturbance in the area.     

Analytical approximate wave form for asymmetric waves

A simple analytical formulation that reproduces a skewed, nonlinear near-bed wave orbital velocity is presented. It contains four free parameters, where two are solely related to the velocity and acceleration skewnesses. The equation is compared with other models and is validated against field and laboratory experiments. The results reveal that it can simulate a wide range of nonlinear wave shapes, reproducing satisfactorily the measured nonlinear wave particle velocity. Also, the new expression overcomes some limitations of the other models. The new formulation is therefore capable of being used in many engineering applications that require the use of representative wave forms.     

Using ichnofossils to characterize chert tools: A preliminary study from Southern Iberia

Characterizing raw material of stone tools used by Late Neolithic and Copper Age communities is important for interpreting access to available sources and establishing regional routes of distribution. Ichnological analysis may be used to help characterize lithic material and determine the source of artifacts. Here we report for the first time the existence of trace fossils in artifacts from the Late Neolithic and Copper Age of southern Spain. Ichnological analysis indicates a trace fossil assemblage consisting of relatively scarce small‐sized Chondrites and abundant Phycosiphon. A regional survey of natural outcrops and chert quarries indicates the presence of discrete trace fossils only in the samples from geological formations that are part of the Campo de Gibraltar Complex. Ichnological composition in these samples is similar to that discerned in the artifacts and suggests that this was the probable source of the chert used in tool manufacture. © 2010 Wiley Periodicals, Inc.     

Lateglacial and Holocene palaeoenvironments at Sierra La Madera,northwestern Mexico: Sharp signals of Younger Dryas and North American monsoon

During the last glacial termination, the climate system experienced intense global variations whose causes and impacts are not fully defined, particularly for low latitudes. The northwestern Mexico Sky Islands present a climate-sensitive ideal setting to record palaeoecological and palaeoclimatic changes due to their physiographic complexity and location in the ecotone between temperate and tropical ecosystems. High-resolution pollen analysis and a detailed sedimentological study were conducted at the Ciénega Tonibabi tropical thorn scrub site. The 15 540–0 cal a bp nearly continuous record shows that the North Atlantic Ocean did have a cold and humid climatic influence during the glacial stages of the end of the Pleistocene, including a sharp pulse during the Younger Dryas. However, a shift to the Pacific Ocean influence occurred during the Holocene, which led to the development of the El Niño conditions prevailing today. Colder and warmer phases follow one another with higher or lower winter precipitation, including a sharp Bølling–Allerød and development and intensification of the North American monsoon. They are reflected in hydrological changes as well as in the advances, retreats and intermingling of coniferous forests and tropical thorn scrub.