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1.
Sidedness polymorphism in flatfish has been linked to ecological selection between morphs. However, the alternate hypothesis that morphological differences between right‐ and left‐sided forms may be due to errors during development, as a consequence of disturbed homeostasis, which still remains largely unexplored. Here, we examined the case of Platichthys flesus (flounder), a polymorphic flatfish exhibiting large and clinal variation in the frequency of the left‐sided morph, which is the reversed condition in this generally right‐sided species. An integrated approach consisting of the analyses of shape variation, stomach contents, and skeletal anomalies was used. Morphological differences were observed between morphs, which are in agreement with previous findings in a congeneric species (Platichthys stellatus). In parallel, significant differences in feeding choices were detected, suggesting a coherent association between subtle morphological differences between morphs and their use of trophic resources. Skeletal anomalies and meristic counts did not corroborate the hypothesis that morphometric divergence in reversed individuals may be caused or reinforced by developmental instability. J. Morphol. 2012. © 2011 Wiley Periodicals, Inc.  相似文献   

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Since 1989, efforts to understand the nature of interfirm resource sharing in the form of industrial symbiosis and to replicate in a deliberate way what was largely self‐organizing in Kalundborg, Denmark have followed many paths, some with much success and some with very little. This article provides a historical view of the motivations and means for pursuing industrial symbiosis—defined to include physical exchanges of materials, energy, water, and by‐products among diversified clusters of firms. It finds that “uncovering” existing symbioses has led to more sustainable industrial development than attempts to design and build eco‐industrial parks incorporating physical exchanges. By examining 15 proposed projects brought to national and international attention by the U.S. President's Council on Sustainable Development beginning in the early 1990s, and contrasting these with another 12 projects observed to share more elements of self‐organization, recommendations are offered to stimulate the identification and uncovering of already existing “kernels” of symbiosis. In addition, policies and practices are suggested to identify early‐stage precursors of potentially larger symbioses that can be nurtured and developed further. The article concludes that environmentally and economically desirable symbiotic exchanges are all around us and now we must shift our gaze to find and foster them.  相似文献   

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Population dynamics, economy, and human demography started with Malthus, the idea that population growth is limited by resources and “positive checks” occur when population growth overshoots the available resources. In fact, historical evidence indicates that long‐term climate changes have destabilized civilizations and caused population collapses via food shortages, diseases, and wars. One of the worst population collapses of human societies occurred during the early fourteenth century in northern Europe; the “Great Famine” was the consequence of the dramatic effects of climate deterioration on human population growth. Thus, part of my motivation was to demonstrate that simple theoretical‐based models can be helpful in understanding the causes of population change in preindustrial societies. Here, the results suggest that a logistic model with temperature as a “lateral” perturbation effect is the key element for explaining the population collapse exhibited by the European population during the “Great Famine”.  相似文献   

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Continental and insular Southeast Asia were originally endowed with vast areas of luxurious Tropical Evergreen Forest. Mainly since the sixties of the last century these tropical rainforests have been under a steadily increasing pressure due to intensive logging for commercial purposes and the increasing number of people depending on the given environment for more agricultural land and for fuel wood.One innovative approach to combine the necessities of rural development, safe natural resource management and biodiversity restoration was developed under the acronym “Rainforestation Farming” on the island of Leyte in the Philippines. More than 100 different local forests and fruit tree species were tested and planted in a near-to-nature planting scheme concerning species composition in a former degraded area covered by Imperata cylindrica.The recommended planting scheme includes both sun-requiring trees and shade-loving trees, highly valuable timber trees and fruit trees. During the first year of planting, nursery grown sun-loving trees were planted at close distance of 2×2 m to quickly reach the condition of a closed canopy and therefore shading out of the grass. During the second year, shade-loving trees, coming from either the nursery or from the natural forest in the form of seedlings sitting under mother trees, were planted under the established first year pioneers.To support the protection of the remaining forest, particularly the mother trees as resource for seedlings and to spur biodiversity rehabilitation efforts through people's participation a support system with community organisers was established. Already after four years some highly endangered species like the herbivorous Flying Lemure, Gynocephalus volans, and the insectivorous nocturnal ape, Tarsius syrichta, moved back into parts of the reforested closed canopy areas of the research and model farm.  相似文献   

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Technological progress and adoption are fundamentally interconnected with environmental challenges faced by society. At the product level, researchers often explore the interplay between technological change and the environment by tracking trends in impacts per unit functionality—for example, gasoline consumed per distance traveled by a vehicle. In this article, we explore an alternative measure: “typical product.” A typical product measure accounts for changes in consumers’ demand and use of products as product quality improves—for example, gasoline consumed for a typical driving pattern for a vehicle. We compare and contrast functionality and typical product measures through a case study of electricity use to fabricate Intel desktop microprocessors from 1995 to 2006. The functionality normalization is measured in terms of electricity use per transistor produced. Results show rapid and sustained exponential decrease. The “typical product” measures electricity use per typical desktop microprocessor of a given year (e.g., a Pentium II in 1998, a Pentium IV in 2002). Results show that, despite fluctuations, energy use per typical microprocessor is roughly constant over the 12‐year period. The explanation of this result is that although technological progress dramatically reduces the energy needed per transistor, it also induces demand for more powerful chips, which contain many more transistors. The typical product measure has applications in defining functional units in life cycle assessment, characterizing rebound effects, and measuring energy efficiency trends.  相似文献   

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Like many economic exchanges, industrial symbiosis (IS) is thought to be influenced by social relationships and shared norms among actors in a network. While many implicit references to social characteristics exist throughout the literature, there have been few explicit attempts to operationalize and measure the concepts. The “short mental distance,”“trust,”“openness,” and “communication” recorded among managers in Kalundborg, Denmark, set a precedent for examining and encouraging social interactions among key personnel in the dozens of eco‐industrial networks around the world. In this article we explore the relationships among various aspects of social embeddedness, social capital, and IS. We develop a conceptual framework and an approach using quantitative and qualitative methods to identify and measure these social characteristics, including social network structure, communication, and similarities in norms and conceptions of waste, and apply them in an industrial network in Nanjangud, South India. The findings suggest that there is a fairly high level of shared norms about dealing with waste—the “short mental distance”—in this network, but by‐product transactions are only weakly correlated with the structure and content of communication among managers. Replication of this approach can increase the understanding and comparability of the role of social characteristics in eco‐industrial activities around the world.  相似文献   

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Macrovibrissae are specialized tactile sensory hairs present in most mammalian orders, used in maxillary mechanoreception or “face touch.” Some mammals have highly organized vibrissae and are able to “whisk” them. Movement of vibrissae is influenced by intrinsic vibrissa musculature, striated muscle bands that attach directly to the vibrissa capsule. It is unclear if primates have organized vibrissae or intrinsic vibrissa musculature and it is uncertain if they can move their vibrissae. The present study used histomorphological techniques to compare vibrissae among 19 primates and seven non‐primate mammalian taxa. Upper lips of these mammals were sectioned and processed for histochemical analysis. While controlling for phylogenetic effects the following hypotheses were tested: 1) mammals with well‐organized vibrissae possess intrinsic vibrissa musculature and 2) intrinsic vibrissa musculature is best developed in nocturnal, arboreal taxa. Our qualitative analyses show that only arboreal, nocturnal prosimians possess intrinsic musculature. Not all taxa that possessed organized vibrissae had intrinsic vibrissa musculature. Phylogenetic comparative analyses revealed a 70% probability that stem mammals, primates, and haplorhines possessed intrinsic vibrissa musculature and well‐organized vibrissae. These two traits most likely coevolved according to a discrete phylogenetic analysis. These results indicate that nocturnal, arboreal primates have the potential to more actively use their vibrissae in spatial recognition and navigation tasks than diurnal, more terrestrial species, but there is a clear phylogenetic signal involved in the evolution of primate vibrissae and “face touch.” Am J Phys Anthropol, 2013. © 2012 Wiley Periodicals, Inc.  相似文献   

8.
This commentary responds to the previously published Journal of Industrial Ecology article “The Employment Footprints of Nations: Uncovering Master‐Servant Relationships” by Alsamawi and colleagues. Their article uses extended input‐output analysis to calculate employment and income footprints and, consequently, quantifies and provides an analysis of the average wages embodied in consumption of countries in comparison with the wages received by domestic workers. In effect, Alsamawi and colleagues show the extent of inequality in labor income, especially between developed and developing economies, traced throughout the global supply chains, but ignore the price differentials existing between countries in their discussion of the welfare implications of global trade on workers. This commentary contends the appropriateness of adjusting nominal compensation of workers to purchasing power parity (PPP) when undertaking global comparisons that pertain to well‐being and recalculates the employment footprints and income footprints of nations with PPP adjustment. The price adjustment in this work is intended to show a more accurate depiction of the disparity among workers of different nations when their labor incomes are deflated by the index price of consumption goods in their country. Using observations covering 189 countries and 14,839 sectors for the period 1990–2011, the results of the adjustment reveal that the ratio of domestic wages to foreign wages paid in support of a country's consumption (footprint wages) tends to be underestimated for labor‐exporting countries (developing economies with relatively cheaper consumption goods) and overestimated for labor‐importing countries (developed economies with more expensive consumption goods), thus demonstrating, generally, relatively less income inequality than previously exposed.  相似文献   

9.
This article reports a new application of material and energy accounting techniques to characterize and quantify the relationships between material input (and the related energy flows and emissions) and the services provided (i.e., material input per service unit [MIPS]) at the neighborhood level. The case study focuses on China's small residential district (SRD). It is concluded that linking a service (in this case, residential function) enabled by a given product (neighborhood development) to the amount of materials, energy, and emissions used or produced in creating that product offers a potential way to reduce the environmental impact of that service through more efficient use of materials, enlarged service scales, and improved buying decisions.  相似文献   

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“Inflammatory” Cytokines   总被引:4,自引:0,他引:4  
If cytokines are constitutively expressed by and act on neurons in normal adult brain, then we may have to modify our current view that they are predominantly inflammatory mediators. We critically reviewed the literature to determine whether we could find experimental basis for such a modification. We focused on two "proinflammatory" cytokines, interleukin (IL)-1 and tumor necrosis factor-alpha (TNFalpha) because they have been most thoroughly investigated in shaping our current thinking. Evidence, although equivocal, indicates that the genes coding for these cytokines and their accessory proteins are expressed by neurons, in addition to glial cells, in normal brain. Their expression is region- and cell type-specific. Furthermore, bioactive cytokines have been extracted from various regions of normal brain. The cytokines' receptors selectively are present on all neural cell types, rendering them responsive to cytokine signaling. Blocking their action modifies multiple neural "housekeeping" functions. For example, blocking IL-1 or TNFalpha by several independent means alters regulation of sleep. This indicates that these cytokines likely modulate in the brain behavior of a normal organism. In addition, these cytokines are likely involved in synaptic plasticity, neural transmission, and Ca2+ signaling. Thus, the evidence strongly suggests that these cytokines perform neural functions in normal brain. We therefore propose that they should be thought of as neuromodulators in addition to inflammatory mediators.  相似文献   

15.
One of the means of creating a more robust methodology for ecological restoration involves reducing the gap between ecological theory and restoration practices. A common strategy to do so is using meta‐analysis to understand key drivers of restoration outcomes. “Active” and “passive” is a dichotomy often used to separate restoration strategies in such meta‐analyses. We investigate previously raised concerns about selection bias and subjective categorization of strategies. We promote a paired experimental design in future empirical research and propose the use of three categories of restoration strategy in lieu of “passive” and “active” to alleviate inconsistency in definitions and categorization.  相似文献   

16.
There is an intensive search for heterogeneous single atom catalysts (SACs) of high activity, efficiency, durability, and selectivity for a wide variety of electrocatalytic conversion and chemical reactions, such as the hydrogen evolution reaction (HER), oxygen evolution/reduction reaction (OER and ORR), CO2 reduction reaction (CO2 RR), and nitrogen reduction reaction (NRR). With the downsizing from nanoparticles and clusters to single atoms, there are steady changes in the bond and coordination environment for each and every atom involved. Indeed, the single atoms in these electrocatalysts are not “singles”; they are “married” to the supporting surfaces, and their performance is controlled by the bonding and coordination with the substrate surfaces. Herein, an overview is presented on the brief history leading to the rapid development of SACs and their current status, by focusing on their synthesis, control of composition, strategies to realize single atoms with the desired bonds and coordination, and targeted performance in selected reactions. Their applications in the selected spectrum of energy conversion and chemical reactions are discussed, in relation to their structures at varying length scales down to the atomic level. A particular emphasis is placed on on‐going research activities, together with the future perspectives and particular challenges for SACs.  相似文献   

17.
In this review, we focus on strategies for designing functional nano gene carriers, as well as choosing therapeutic genes targeting the tumor microenvironment. Gene mutations have a great impact on the occurrence of cancer. Thus, gene therapy plays a major role in cancer therapy and has the potential to cure cancer. Well‐designed gene therapy largely relies on effective gene carriers, which can be divided into viral carriers and non‐viral carriers. A gene carrier delivers functional genes to their intracellular target and avoids nucleic acids being degraded by nucleases in the serum. Most conventional cancer gene therapies only target cancer cells and do not appear to be sufficintly efficient to pass clinical trials. Accumulating evidence has shown that extending the therapeutic strategies to the tumor microenvironment, rather than the tumor cell itself, can allow more options for achieving robust anti‐cancer efficiency. In addition, unusual features between tumor microenvironment and normal tissues, such as a lower pH, higher glutathione and reactive oxygen species concentrations, and overexpression of some enzymes, facilitate the design of smart stimuli‐responsive gene carriers regulated by the tumor microenvironment. These carriers interact with nucleic acids and then form stable nanoparticles under physiological conditions. By regulation of the tumor microenvironment, stimuli‐responsive gene carriers are able to change their properties and achieve high gene delivery efficiency. Considering the tumor microenvironment as the “regulator” and “target” when designing gene carriers and choosing therapeutic genes shows significant benefit with respect to improving the accuracy and efficiency of cancer gene therapy.  相似文献   

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The transdiagnostic expression of psychotic experiences in common mental disorder (anxiety/depression/substance use disorder) is associated with a poorer prognosis, and a small minority of people may indeed develop a clinical picture that meets criteria for schizophrenia. However, it appears neither useful nor valid to observe early states of multidimensional psychopathology in young people through the “schizo”‐prism, and apply misleadingly simple, unnecessary and inefficient binary concepts of “risk” and “transition”. A review of the “ultra‐high risk” (UHR) or “clinical high risk” (CHR) literature indicates that UHR/CHR samples are highly heterogeneous and represent individuals diagnosed with common mental disorder (anxiety/depression/substance use disorder) and a degree of psychotic experiences. Epidemiological research has shown that psychotic experiences are a (possibly non‐causal) marker of the severity of multidimensional psychopathology, driving poor outcome, yet notions of “risk” and “transition” in UHR/CHR research are restrictively defined on the basis of positive psychotic phenomena alone, ignoring how baseline differences in multidimensional psychopathology may differentially impact course and outcome. The concepts of “risk” and “transition” in UHR/CHR research are measured on the same dimensional scale, yet are used to produce artificial diagnostic shifts. In fact, “transition” in UHR/CHR research occurs mainly as a function of variable sample enrichment strategies rather than the UHR/CHR “criteria” themselves. Furthermore, transition rates in UHR/CHR research are inflated as they do not exclude false positives associated with the natural fluctuation of dimensional expression of psychosis. Biological associations with “transition” thus likely represent false positive findings, as was the initial claim of strong effects of omega‐3 polyunsatured fatty acids in UHR samples. A large body of UHR/CHR intervention research has focused on the questionable outcome of “transition”, which shows lack of correlation with functional outcome. It may be more productive to consider the full range of person‐specific psychopathology in all young individuals who seek help for mental health problems, instead of “policing” youngsters for the transdiagnostic dimension of psychosis. Instead of the relatively inefficient medical high‐risk approach, a public health perspective, focusing on improved access to a low‐stigma, high‐hope, small scale and youth‐specific environment with acceptable language and interventions may represent a more useful and efficient strategy.  相似文献   

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