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1.
Jack Kerouac, the author of On The Road, was a central figure of the Beat Generation, a generation which rebelled against middle-class conformity in post–World War II America. Kerouac described himself as “a religious wanderer” (Kerouac 2006: 2), but an examination of his texts and life suggest his travels may also be understood as tourism. Viewed through the prism of tourism, this study will argue, for example, that MacCannell’s notion of the tourist’s quest for reality and authenticity (MacCannell 1989: 3) provides some insight into why Kerouac wrote that just south of Macon, Georgia, he and his travelling companion Neal Cassady stopped and got out of the car, “and suddenly both of us were stoned with joy to realize that in the darkness all around us was fragrant green grass and the smell of fresh manure and warm waters” (Kerouac 1957: 115). As Kerouac rebelled against being, as one of his protagonists in The Dharma Bums put it, “imprisoned in a system of work, produce, consume, work, produce, consume” (Kerouac 2006: 73) he travelled across America on a rapidly improving network of highways, turning “mobility into a retreat” (Holladay and Holton 2009: 42). Kerouac alternately identified himself as a hobo (Kerouac 1973: 181) and “not a real hobo” (Kerouac 1973: 173), but this article asks whether Kerouac’s travels were those of the last in a line of wanderers rebelling against conformity and modernization or a precursor of mobile mass tourism in America.  相似文献   

2.
Recently, some of the older literature purported to demonstrate a positive interaction between solar radiation and thermal stress on the phenomenon of coral bleaching have been called into question (Dunne 2010). Dunne (2010) correctly points out important experimental design and analysis issues related to the interpretation of multi-factorial designs, and both positive and negative interactive effects, with emphasis on the point that once interactive effects are detected no interpretation of the main effects of a multi-factorial design is appropriate. Dunne (2010) presents a number of statistical analyses to address this issue that are valuable and deserve significant discussion. While Dunne (2010) was specifically addressing the issue of the misuse of the term “synergy” some of the analyses presented may have understated the presence of such interactions. Here, I conduct a re-analysis of specific datasets using another potentially useful approach that shows both positive and negative interactions during experiments on bleaching.  相似文献   

3.
The type specimens of platycephalid Platycephalus endrachtensis Quoy and Gaimard 1825 are regarded as being conspecific with Platycephalus arenarius Ramsay and Ogilby 1886, so the latter becomes a junior synonym. This species is characterized as having a caudal fin with four or more longitudinal dark bands and lacking a yellow blotch. It is also found that Platycephalus westraliae (Whitley 1938), which had been considered to be a junior synonym of Platycephalus bassensis Cuvier 1829, is a valid species. Specimens that recently had been mistakenly identified as “P. endrachtensis,” having the caudal fin with three or four longitudinal dark bands and a yellow blotch on the upper lobe, should be referred to P. westraliae.  相似文献   

4.
In this paper architectural forms are presented as symbolic forms issued from the complex semiosis that characterises human cognition (Ferreira (2007, 2010)). Being semiotic objects, these symbolic forms are, consequently, context- dependent_they emerge and have meaning, i.e., they are assigned a functional and/or aesthetic value, in particular physical, social and cultural frameworks. As it happens with all semiotic objects, architectural forms, whatever their nature, are not static but highly interactive. In fact, they act as agents of specific semiotic processes, engaged in a permanent dialectic relationship with the environment they are embedded in. From this dialectics important physical, social, cultural and economic changes frequently arise, redefining this way the original framework for decades to come. As Pallasmaa (2009) points out: “Architecture is existentially rooted, and it expresses fundamental existential experiences, the complex condensation of how it feels to be human being in this world. Architecture grounds and frames existence and creates specific horizons of perception, understanding and identity.” Architecture happens in the context of particular landscapes both natural and man-made, individuating spaces, assigning them an identity, turning the frequently undifferentiated physical environment into “locus”, “place”, “site”, “ort”, definitely contributing to the definition of the mental map that individual minds are able to share collectively. The fundamental role played by architectural forms in the definition of “place” and identity and in the shaping or reshaping of a physical, social and cultural environment is analysed in this paper through a case study that observes the consequences of this dynamics in the development of the social and cultural tissue of a particular city.  相似文献   

5.
According to Charles Hauss, “[i]n the last few years, reconciliation has become one of the ‘hottest’ topics in the increasingly ‘hot’ field of conflict resolution” (2003, ?1). However, despite the apparent interest in this “hot” academic topic (which is becoming increasingly warm in Canada as our own Truth and Reconciliation Commission commences), reconciliation studies have been dominated by Truth-based approaches. The restrictions of these approaches, which emphasize objectivity and rationality, often elide the body and the primacy of emotions in the reparative process. This essay begins a conversation on the role of the body and emotion in the study of reconciliation by engaging the work being done in the social sciences with contemporary trends in critical theory and literature. I argue that by looking at the fundamental role the body plays on the “road to reconciliation” we can devise a more vital approach to conflict resolution and the various processes that make it up.  相似文献   

6.
Fitts’ law is a well established empirical formula, known for encapsulating the “speed-accuracy trade-off”. For discrete, manual movements from a starting location to a target, Fitts’ law relates movement duration to the distance moved and target size. The widespread empirical success of the formula is suggestive of underlying principles of human movement control. There have been previous attempts to relate Fitts’ law to engineering-type control hypotheses and it has been shown that the law is exactly consistent with the closed-loop step-response of a time-delayed, first-order system. Assuming only the operation of closed-loop feedback, either continuous or intermittent, this paper asks whether such feedback should be predictive or not predictive to be consistent with Fitts law. Since Fitts’ law is equivalent to a time delay separated from a first-order system, known control theory implies that the controller must be predictive. A predictive controller moves the time-delay outside the feedback loop such that the closed-loop response can be separated into a time delay and rational function whereas a non- predictive controller retains a state delay within feedback loop which is not consistent with Fitts’ law. Using sufficient parameters, a high-order non-predictive controller could approximately reproduce Fitts’ law. However, such high-order, “non-parametric” controllers are essentially empirical in nature, without physical meaning, and therefore are conceptually inferior to the predictive controller. It is a new insight that using closed-loop feedback, prediction is required to physically explain Fitts’ law. The implication is that prediction is an inherent part of the “speed-accuracy trade-off”.  相似文献   

7.
Mammalian prenatal neocortical development is dominated by the synchronized formation of the laminae and migration of neurons. Postnatal development likewise contains “sensitive periods” during which functions such as ocular dominance emerge. Here we introduce a novel neuroinformatics approach to identify and study these periods of active development. Although many aspects of the approach can be used in other studies, some specific techniques were chosen because of a legacy dataset of human histological data (Conel in The postnatal development of the human cerebral cortex, vol 1–8. Harvard University Press, Cambridge, 1939–1967). Our method calculates normalized change vectors from the raw histological data, and then employs k-means cluster analysis of the change vectors to explore the population dynamics of neurons from 37 neocortical areas across eight postnatal developmental stages from birth to 72 months in 54 subjects. We show that the cortical “address” (Brodmann area/sub-area and layer) provides the necessary resolution to segregate neuron population changes into seven correlated “k-clusters” in k-means cluster analysis. The members in each k-cluster share a single change interval where the relative share of the cortex by the members undergoes its maximum change. The maximum change occurs in a different change interval for each k-cluster. Each k-cluster has at least one totally connected maximal “clique” which appears to correspond to cortical function.  相似文献   

8.
In analogy to proteins, the function of RNA depends on its structure and dynamics, which are encoded in the linear sequence. While there are numerous methods for computational prediction of protein 3D structure from sequence, there have been very few such methods for RNA. This review discusses template-based and template-free approaches for macromolecular structure prediction, with special emphasis on comparison between the already tried-and-tested methods for protein structure modeling and the very recently developed “protein-like” modeling methods for RNA. We highlight analogies between many successful methods for modeling of these two types of biological macromolecules and argue that RNA 3D structure can be modeled using “protein-like” methodology. We also highlight the areas where the differences between RNA and proteins require the development of RNA-specific solutions.  相似文献   

9.
A recently proposed mathematical model of a “core” set of cellular and molecular interactions present in the developing vertebrate limb was shown to exhibit pattern-forming instabilities and limb skeleton-like patterns under certain restrictive conditions, suggesting that it may authentically represent the underlying embryonic process (Hentschel et al., Proc. R. Soc. B 271, 1713–1722, 2004). The model, an eight-equation system of partial differential equations, incorporates the behavior of mesenchymal cells as “reactors,” both participating in the generation of morphogen patterns and changing their state and position in response to them. The full system, which has smooth solutions that exist globally in time, is nonetheless highly complex and difficult to handle analytically or numerically. According to a recent classification of developmental mechanisms (Salazar-Ciudad et al., Development 130, 2027–2037, 2003), the limb model of Hentschel et al. is “morphodynamic,” since differentiation of new cell types occurs simultaneously with cell rearrangement. This contrasts with “morphostatic” mechanisms, in which cell identity becomes established independently of cell rearrangement. Under the hypothesis that development of some vertebrate limbs employs the core mechanism in a morphostatic fashion, we derive in an analytically rigorous fashion a pair of equations representing the spatiotemporal evolution of the morphogen fields under the assumption that cell differentiation relaxes faster than the evolution of the overall cell density (i.e., the morphostatic limit of the full system). This simple reaction–diffusion system is unique in having been derived analytically from a substantially more complex system involving multiple morphogens, extracellular matrix deposition, haptotaxis, and cell translocation. We identify regions in the parameter space of the reduced system where Turing-type pattern formation is possible, which we refer to as its “Turing space.” Obtained values of the parameters are used in numerical simulations of the reduced system, using a new Galerkin finite element method, in tissue domains with nonstandard geometry. The reduced system exhibits patterns of spots and stripes like those seen in developing limbs, indicating its potential utility in hybrid continuum-discrete stochastic modeling of limb development. Lastly, we discuss the possible role in limb evolution of selection for increasingly morphostatic developmental mechanisms.  相似文献   

10.
Roy Ellen 《Economic botany》2008,62(3):483-496
Ethnomycology among the Nuaulu of the Moluccas: Putting Berlin’s “General Principles” of Ethnobiological Classification to the Test. Berlin's (Ethnobiological Classification: Principles of Categorization of Plants and Animals in Traditional Societies. Princeton University Press, New Jersey, 1992) universal theories of ethnobiological classification have provided an indispensable common rubric to compare data from diverse sources. This paper examines these principles with respect to the naming of mushrooms by the Nuaulu on the eastern Indonesian island of Seram, a people for whom mushrooms have only marginal significance. Concordance to Berlin’s principles is noted in some respects, but the small proportion of overall mycological diversity that is treated, the lack of consistently labeled intermediate rankings, the conflation between specific and generic levels, and the importance of utilitarian considerations challenge Berlin's hierarchically ranked “general purpose” (i.e., natural) model of folk biological taxonomy. A comparative review of the literature on other, mostly tropical ethnomycological classifications, is also included.  相似文献   

11.
Giambattista Brocchi’s (1814) monograph (see Dominici, Evo Edu Outreach, this issue, 2010) on the Tertiary fossils of the Subappenines in Italy—and their relation to the living molluscan fauna—contains a theoretical, transmutational perspective (“Brocchian transmutation”). Unlike Lamarck (1809), Brocchi saw species as discrete and fundamentally stable entities. Explicitly analogizing the births and deaths of species with those of individual organisms (“Brocchi’s analogy”), Brocchi proposed that species have inherent longevities, eventually dying of old age unless driven to extinction by external forces. As for individuals, births and deaths of species are understood to have natural causes; sequences of births and deaths of species produce genealogical lineages of descent, and faunas become increasingly modernized through time. Brocchi calculated that over 50% of his fossil species are still alive in the modern fauna. Brocchi’s work was reviewed by Horner (1816) in Edinburgh. Brocchi’s influence as a transmutational thinker is clear in Jameson’s (1827) “geological illustrations” in his fifth edition of his translation of Cuvier’s Theory of the Earth (read by his student Charles Darwin) and in the anonymous essays of 1826 and 1827 published in the Edinburgh New Philosophical Journal—which also carried a notice of Brocchi’s death in 1827. The notion that new species replace older, extinct ones—in what today would be called an explicitly phylogenetic context—permeates these essays. Herschel’s (1830) discussion of temporal replacement of species and the modernization of faunas closely mirrors these prior discussions. His book, dedicated to the search for natural causes of natural phenomena, was read by Charles Darwin while a student at Cambridge. Darwin’s work on HMS Beagle was in large measure an exploration of replacement patterns of “allied forms” of endemic species in time and in space. His earliest discussions of transmutation, in his essay February 1835, as well as the Red Notebook and the early pages of Notebook B (the latter two written in 1837 back in England), contain Brocchi’s analogy, including the idea of inherent species longevities. Darwin’s first theory of the origin of species was explicitly saltational, invoking geographic isolation as the main cause of the abrupt appearance of new species. We conclude that Darwin was testing the predicted patterns of both Brocchian and Lamarckian transmutation as early as 1832 at the outset of his work on the Beagle.  相似文献   

12.
Penalized regression incorporating prior dependency structure of predictors can be effective in high-dimensional data analysis (Li and Li in Bioinformatics, 24:1175–1118, 2008). Pan et al. (Biometrics, 66:474–484, 2010) proposed a penalized regression method for better outcome prediction and variable selection by smoothing parameters over a given predictor network, which can be applied to analysis of microarray data with a given gene network. In this paper, we develop two modifications to their method for further performance enhancement. First, we employ convex programming and show its improved performance over an approximate optimization algorithm implemented in their original proposal. Second, we perform bias reduction after initial variable selection through a new penalty, leading to better parameter estimates and outcome prediction. Simulations have demonstrated substantial performance improvement of the proposed modifications over the original method.  相似文献   

13.
Several authors have recently argued that invasion biologists should adopt a more objective and dispassionate stance towards invasive species. Brown and Sax (Austral Ecol 29:530–536, 2004; Austral Ecol 30:481–483, 2005) assert that invasion biologists risk their objectivity, “commit the naturalist fallacy” or “embark on a slippery slope” with engaged concern about invasive species. Elsewhere, Colautti and MacIsaac (Divers Distrib 10:135–141, 2004) propose a neutral language for invasion biology, one that insulates scientific from popular discussion about invasive species. While there is certainly hyperbole about the effects of some invasive species, the type of objectivity promoted in these papers may often be inappropriate for invasion biology. It implies a policy of non-action that is inconsistent with the conservation values of many invasion biologists. To engage these values, invasion biologists can adopt deliberative methods for environmental problem-solving that involve stakeholders in their research design and which still promote high standards of scientific rigor.  相似文献   

14.
The Role of Organic Acids in the Domestication of Oxalis tuberosa: A New Model for Studying Domestication Resulting in Opposing Crop Phenotypes. Though few crops display directly opposing domesticated phenotypes, these crops may be the key to understanding domestication processes that address conflicting selective pressures in the agricultural ecosystem. Two relatively well-known examples are cassava (Manihot esculenta Crantz), which has high-cyanide and low-cyanide varieties, and potato (Solanum section Petota). Among the potatoes are several species, including the common potato (Solanum tuberosum L.), that have low levels of glycoalkaloids and there are other species of “bitter potato” with elevated levels of glycoalkaloids. We propose that Oxalis tuberosa Molina, “oca,” may represent a third example of such a crop system, with opposing high organic acid and low organic acid cultivars. Each cultivar set has different cultural food preparation practices (“use-categories”), similar to the “use-categories” that have been described for potatoes in the Andes (Brush et al. Economic Botany 35;70–88, 1981; Zimmerer Journal of Biogeography 18;165–178, 1991). Our initial analyses suggest that organic acids in tubers may be an important biochemical difference between use-categories, based on both oxalic acid and pH data. Here, we review our understanding of organic acids in oca tubers, while highlighting areas that merit further investigation.  相似文献   

15.
Since its introduction into eastern North America in the 1940s, the eastern population of house finches (Carpodacus mexicanus) has become partially migratory, unlike its nonmigratory source population in southern California (Able and Belthoff in Proc. R. Soc. Lond. 265 (1410), 2063–2071, 1998; Belthoff and Gauthreaux in Condor 93, 374–382, 1991). The infectious disease mycoplasmal conjunctivitis (pathogen Mycoplasma gallisepticum or “MG”), which has been monitored in the house finch population since its appearance around 1993 (Dhondt et al. in J. Wild. Dis. 34 (2), 265–280, 1998), may induce higher mortality rates among populations in more northerly latitudes relative to more southerly populations. Here, we investigate the potential impact of this differential disease mortality on the migratory structure of the eastern house finch population using an epidemic modeling approach. Analytical and computational results suggest the ongoing MG epidemic in the eastern house finch could lead to increases in the percentage of and the total number of migrating individuals in a population despite overall population declines, assuming relatively high winter mortality rates in the north eastern part of their range. These results also suggest that empirical evidence of such a change in migratory structure would be most noticeable in northerly inland populations that showed significant declines following the initial outbreak of MG in the east.  相似文献   

16.
Many association methods use a subset of genotyped single nucleotide polymorphisms (SNPs) to capture or infer genotypes at other untyped SNPs. We and others previously showed that tag SNPs selected to capture common variation using data from The International HapMap Consortium (Nature 437:1299–1320, 2005), The International HapMap Consortium (Nature 449:851–861, 2007) could also capture variation in populations of similar ancestry to HapMap reference populations (de Bakker et al. in Nat Genet 38:1298–1303, 2006; González-Neira et al. in Genome Res 16:323–330, 2006; Montpetit et al. in PLoS Genet 2:282–290, 2006; Mueller et al. in Am J Hum Genet 76:387–398, 2005). To capture variation in admixed populations or populations less similar to HapMap panels, a “cosmopolitan approach,” in which all samples from HapMap are used as a single reference panel, was proposed. Here we refine this suggestion and show that use of a “weighted reference panel,” constructed based on empirical estimates of ancestry in the target population (relative to available reference panels), is more efficient than the cosmopolitan approach. Weighted reference panels capture, on average, only slightly fewer common variants (minor allele frequency > 5%) than the cosmopolitan approach (mean r 2 = 0.977 vs. 0.989, 94.5% variation captured vs. 96.8% at r 2 > 0.8), across the five populations of the Multiethnic Cohort, but entail approximately 25% fewer tag SNPs per panel (average 538 vs. 718). These results extend a recent study in two Indian populations (Pemberton et al. in Ann Hum Genet 72:535–546, 2008). Weighted reference panels are potentially useful for both the selection of tag SNPs in diverse populations and perhaps in the design of reference panels for imputation of untyped genotypes in genome-wide association studies in admixed populations. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

17.
To clarify how the information of spatiotemporal sequence of the hippocampal CA3 affects the postsynaptic membrane potentials of single pyramidal cells in the hippocampal CA1, the spatio-temporal stimuli was delivered to Schaffer collaterals of the CA3 through a pair of electrodes and the post-synaptic membrane potentials were recorded using the patch-clamp recording method. The input–output relations were sequentially analyzed by applying two measures; “spatial clustering” and its “self-similarity” index. The membrane potentials were hierarchically clustered in a self-similar manner to the input sequences. The property was significantly observed at two and three time-history steps. In addition, the properties were maintained under two different stimulus conditions, weak and strong current stimulation. The experimental results are discussed in relation to theoretical results of Cantor coding, reported by Tsuda (Behav Brain Sci 24(5):793–847, 2001) and Tsuda and Kuroda (Jpn J Indust Appl Math 18:249–258, 2001; Cortical dynamics, pp 129–139, Springer-Verlag, 2004).  相似文献   

18.
We describe a new macrophyte-based assessment tool for Austrian lakes elaborated according to the requirements of the European Water Framework Directive. Data from 38 out of 45, WFD-relevant (≥50 ha) lakes in Austria collected with the help of a new mapping procedure form the basis for a macrophyte-based lake typology and the definition of reference conditions. Module 1 of the Austrian Index Macrophytes (AIM) focuses on the assessment of trophic state and general impairment of lakes. Several metrics were developed and applied in combination with existing indices to classify lakes into five ecological status classes. The metric “vegetation density” focuses on the overall abundance of macrophytes. Since the lower limit of the macrophyte vegetation in lakes is mainly regulated by the water transparency, the metric “vegetation limit” is closely related to the trophic state of the lake. In deep lakes, macrophytes normally form different vegetation zones. As a result of alteration of the shoreline, artificial water level fluctuations or wave action and even eutrophication, specific zones can be missing. The metric “characteristic zonation” helps to check, if all type-specific vegetation zones are present. The metric “trophic indication” uses the Macrophyte Index after Melzer (Hydrobiologia, 395/396: 181–190, 1999). This term indicates the lake trophic state but, in contrast to the metric “vegetation limit”, it tends to show not only the trophic state of the water column but also, in particular, the nutrient conditions in the sediment. With the help of the metric “species composition,” the species spectrum and the species abundances of the current transect are compared with the species composition at reference sites. The similarity of the datasets is measured as Bray–Curtis Distance (Beals, Advances in Ecological Research, 14: 1–55, 1984). The established metrics cover different aspects of macrophyte vegetation and allow analysing the prevailing pressure. Since the different metrics have a different temporal response to eutrophication and reoligotrophication, additional information on the current state of the lake in relation to these processes can be derived. The successful application of AIM-Module 1 is presented for two Austrian lakes and discussed in relation to other assessment tools. Guest editors: P. N?ges, W. van de Bund, A.C. Cardoso, A. Solimini & A.-S. Heiskanen Assessment of the Ecological Status of European Surface Waters  相似文献   

19.
Animals emit visual signals that involve simultaneous, sequential movements of appendages that unfold with varying dynamics in time and space. Algorithms have been recently reported (e.g. Peters et al. in Anim Behav 64:131–146, 2002) that enable quantitative characterization of movements as optical flow patterns. For decades, acoustical signals have been rendered by techniques that decompose sound into amplitude, time, and spectral components. Using an optic-flow algorithm we examined visual courtship behaviours of jumping spiders and depict their complex visual signals as “speed waveform”, “speed surface”, and “speed waterfall” plots analogous to acoustic waveforms, spectrograms, and waterfall plots, respectively. In addition, these “speed profiles” are compatible with analytical techniques developed for auditory analysis. Using examples from the jumping spider Habronattus pugillis we show that we can statistically differentiate displays of different “sky island” populations supporting previous work on diversification. We also examined visual displays from the jumping spider Habronattus dossenus and show that distinct seismic components of vibratory displays are produced concurrently with statistically distinct motion signals. Given that dynamic visual signals are common, from insects to birds to mammals, we propose that optical-flow algorithms and the analyses described here will be useful for many researchers.Damian O. Elias and Bruce R. Land contributed equallyAn erratum to this article can be found at  相似文献   

20.
Maynard et al. (Coral Reefs 27:745–749, 2008a) claim that much of the concern about the impacts of climate change on coral reefs has been “based on essentially untested assumptions regarding reefs and their capacity to cope with future climate change”. If correct, this claim has important implications for whether or not climate change represents the largest long-term threat to the sustainability of coral reefs, especially given their ad hominem argument that many coral reef scientists are guilty of “popularising worst-case scenarios” at the expense of truth. This article looks critically at the claims made by Maynard et al. (Coral Reefs 27:745–749, 2008a) and comes to a very different conclusion, with the thrust and veracity of their argument being called into question. Contrary to the fears of Grigg (Coral Reefs 11:183–186, 1992), who originally made reference to the Cassandra syndrome due to his concern about the sensationalisation of science, the proposition that coral reefs face enormous challenges from climate change and ocean acidification has and is being established through “careful experimentation, long-term monitoring and objective interpretation”. While this is reassuring, coral reef ecosystems continue to face major challenges from ocean warming and acidification. Given this, it is an imperative that scientists continue to maintain the rigour of their research and to communicate their conclusions as widely and clearly as possible. Given the shortage of time and the magnitude of the problem, there is little time to spare.  相似文献   

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