共查询到20条相似文献,搜索用时 0 毫秒
1.
Although several studies have examined the functional diversity of freshwater macroinvertebrates, the variety of methodologies combined with the absence of a synthetic review make our understanding of this field incomplete. Therefore, we reviewed the current methodology for assessing functional diversity in freshwater macroinvertebrate research. Our review showed that most papers quantified functional diversity using biological traits, among which feeding habits were the most common traits probably due to the assumed links between feeding and ecosystem functions. A large number of diversity measures have been applied for quantifying functional diversity of freshwater macroinvertebrate assemblages, among which Rao’s quadratic entropy looks like the most frequent. In most papers, functional diversity was positively related to taxon richness, and functional redundancy was a key concept in explaining this correlation. Most studies detected strong influence of the environmental factors as well as human impact on functional diversity. Finally, our review revealed that functional diversity research is biased towards European running waters and is hindered by yet insufficient information on the autecology of macroinvertebrates. 相似文献
2.
The effect of water-level (WL) fluctuations on both the structure and functioning of coastal marshes is well documented, and in the past, scientists have demonstrated this by relating historical changes in the areal cover of emergent vegetation (EM) of a particular site to corresponding WL data. This approach of relating areal cover to WL cannot be applied to multiple sites from a region experiencing the same WL because in that instance, WL would be a constant and cannot be used as an explanatory variable for emergent cover. In a previous study of Cootes Paradise Marsh, we proposed the use of a Digital Elevation Model (DEM) to examine the effect of WL fluctuations on emergent plant cover over a 60-year period (1934–1993), and found that the inundated area (IA) was a better predictor of emergent cover than WL. However, the transferability of the marsh-inundation model and the related uncertainty has not yet been tested in a distinct geographic region. In the present article, we test the transferability of the model and develop a regional model of vegetation response to validate the DEM-based method. We confirm the existence of a highly significant relationship between percent IA and percent emergent cover over a large spatial scale in Eastern Lake Ontario. Additionally, we showed that this general relationship might be modified by the degree of urbanization in wetland watersheds. Our results suggest that this DEM-based approach is useful for predicting the aggregate response of EM to annual WL fluctuations and is transferable from local to regional scales. Handling editor: L. M. Bini 相似文献
3.
Hyperhidrosis: a review of current management 总被引:11,自引:0,他引:11
Primary hyperhidrosis is a troublesome disorder of excessive perspiration that affects as much as 1 percent of the population. Sufferers are usually young and are often affected by related social, professional, and psychological problems. Many methods for treating hyperhidrosis exist; however, no single treatment is without its weakness or complications. This article aims to clarify the issues related to the use of each treatment modality, including the most recently proposed method using botulinum toxin. 相似文献
4.
We contrast some recent uses of the concept of male-female conflict, with the type of conflict that is inherent in traditional Darwinian female choice. Females in apparent conflict situations with males may suffer reduced lifetime reproduction, but nevertheless benefit because they obtain sons with superior manipulative abilities. Female defences against male manipulations may not be 'imperfect' because of inability to keep pace with male evolution, but in order to screen males and favour those that are especially good manipulators. We examine the consequences of these ideas, and of the difficulties of obtaining biologically realistic measures of female costs, for some recent theoretical and empirical presentations of male-female conflict ideas, and find that male-female conflict in the new sense is less certain than has been commonly supposed. Disentangling previous sexual selection ideas and the new conflict of interest models will probably often be difficult, because the two types of payoffs are not mutually exclusive. 相似文献
5.
Forti G Agostiano A Barbato R Bassi R Brugnoli E Finazzi G Garlaschi FM Jennings RC Melandri BA Trotta M Venturoli G Zanetti G Zannoni D Zucchelli G 《Photosynthesis research》2006,88(3):211-240
This historical review was compiled and edited by Giorgio Forti, whereas the other authors of the different sections are listed alphabetically after his name, below the title of the paper; they are also listed in the individual sections. This review deals with the research on photosynthesis performed in several Italian laboratories during the last 50 years; it includes research done, in collaboration, at several international laboratories, particularly USA, UK, Switzerland, Hungary, Germany, France, Finland, Denmark, and Austria. Wherever pertinent, references are provided, especially to other historical papers in Govindjee et al. [Govindjee, Beatty JT, Gest H, Allen JF (eds) (2005) Discoveries in Photosynthesis. Springer, Dordrecht]. This paper covers the physical and chemical events starting with the absorption of a quantum of light by a pigment molecule to the conversion of the radiation energy into the stable chemical forms of the reducing power and of ATP. It describes the work done on the structure, function and regulation of the photosynthetic apparatus in higher plants, unicellular algae and␣in photosynthetic bacteria. Phenomena such as photoinhibition and the protection from it are also included. Research in biophysics of photosynthesis in Padova (Italy) is discussed by G.M. Giacometti and G.␣Giacometti (2006). 相似文献
6.
7.
8.
Mary Ann Curran Steven B. Young 《The International Journal of Life Cycle Assessment》2014,19(10):1667-1673
Purpose
Much collective wisdom and experience have been gained as an increasing number of Life Cycle Assessment (LCA) reviews are conducted. However, specifics on how and when to conduct critical review of LCA studies are still lacking. Toward this need, a technical session entitled “LCA Critical Review” was held during the Life Cycle Management (LCM) conference in Gothenburg, Sweden, 26 August 2013. The goal of the session was to have experts address LCA critical review as well as engage attendees in discussing gaps in the current guidance and how the review process can be improved.Methods
The LCM session consisted of six presentations followed by open discussion with all session attendees. This paper begins with a review of the current state-of-the-practice in LCA critical review (CR) followed by a summary of the LCM session. It concludes with suggestions for how the newly drafted technical specification, ISO TS 14071 Critical review processes and reviewer competencies, can be improved as it is being developed.Results and discussion
ISO TS 14071 promises to provide additional guidance to move the practice forward. But at only eight pages in length, its potential effectiveness appears moderate. Additional detailed guidance is needed to move the critical review process toward increased uniformity and clarity of practice, for example, when critical review is necessary.Conclusions
A session on LCA critical review is planned to be held during the Life Cycle Management 2015 conference which will occur in Bordeaux, France (http://lcm2015.org/). Discussion on these issues related to LCA review will be continued. 相似文献9.
Many peptide hormone receptors are over-expressed in human cancer, permitting an in vivo targeting of tumors for diagnostic and therapeutic purposes. NPY receptors are novel and promising candidates in this field. Using in vitro receptor autoradiography, Y1 and Y2 receptors have been found to be expressed in breast carcinomas, adrenal gland and related tumors, renal cell carcinomas, and ovarian cancers in both tumor cells and tumor-associated blood vessels. Pathophysiologically, tumoral NPY receptors may be activated by endogenous NPY released from intratumoral nerve fibers or tumor cells themselves, and mediate NPY effects on tumor cell proliferation and tumoral blood supply. Clinically, tumoral NPY receptors may be targeted with NPY analogs coupled with adequate radionuclides or cytotoxic agents for a scintigraphic tumor imaging and/or tumor therapy. 相似文献
10.
We reviewed the use of captive European starlings (Sturnus vulgaris) in scientific research published between 2000 and 2004. We estimated the numbers of birds used and documented their origin and the range of husbandry regimes employed with the aim of comparing current practice with the new European guidelines for husbandry of laboratory animals. Over the five-year period, 106 primary articles report the use of an estimated total of 2490 captive starlings. The majority of birds were caught from the wild either as adults or fledglings, and only 3% were hand-reared from chicks. There was considerable variation in husbandry. In the majority of cases, standards fell below those currently recommended as best practice in the UK and cited in new European guidelines. The median volume of home cages employed was 0.42 m3 (0.13-5.1 m3, interquartile range), whereas current recommendations suggest a minimum of 1.0 m3 for a singly-housed bird. The median volume of space allowed per bird was 0.13 m3/bird (0.08-1.05 m3/bird, Q1-Q3), whereas current recommendations suggest a minimum of 0.33 m3/bird. Only 27% of the articles mentioned providing any form of environmental enrichment for birds in their home cages. We recommend that more research be conducted into the welfare of starlings to inform legislation and guidelines, and thus maximize the welfare of captive animals. 相似文献
11.
LEARNING OBJECTIVES: After studying this article, the participant should be able to: 1. Describe the differential diagnosis of xanthelasma palpebrarum. 2. Discuss the various nonsurgical and surgical treatment options and their advantages and disadvantages. 3. Describe the circumstances in which recurrence is most likely after treatment. Xanthelasma palpebrarum is the most common cutaneous xanthoma. It typically presents in middle-aged and older adults, most often around the eyelids. The diagnosis can often be made on clinical grounds alone. For the plastic surgeon, it is important to apply an algorithmic approach to the treatment of these lesions. Depending on the size and location, several different methods can be used to address this problem, ranging from simple excision, to laser treatment, to chemical peeling. This article addresses the underlying pathophysiology of xanthelasma and the currently accepted modes of treatment. 相似文献
12.
13.
The aim of the study reported here was to provide some basic and general information on the suitability of an experimental sheep model for conducting in vivo orthopedic studies. The authors have classified the fundamental aspects that should be carefully evaluated when using sheep as an experimental model in orthopedic research: factors strictly related to bone anatomy and formation; and factors strictly affecting bone physiology, such as gastrointestinal mineral and vitamin absorption, and reproductive cycle. Future investigations should address all of the aspects highlighted, since there is no animal with the same anatomic, biochemical, physiologic, and biological characteristics as those of human beings. Moreover, useful data for treating orthopedic patients are based not only on good planning and study design, but also on perfect knowledge of the animal used and the differences between the model and the human being. The authors hope that this report will contribute to extrapolation of reliable data for use of sheep in the orthopedics field. 相似文献
14.
The current status of Helicobacter pylori vaccines: a review 总被引:5,自引:0,他引:5
Kabir S 《Helicobacter》2007,12(2):89-102
15.
Connecting cytokines and brain: a review of current issues 总被引:4,自引:0,他引:4
Cytokines have been a multi-disciplinary research focus for over 2 decades. To date, there have been more than 15,000 articles published concerning the relationship between cytokines and the central nervous system (CNS). Over half of these articles have been published in the last 5 years. From such vast number of studies, two major topics emerge as the critical issues: 1) how do cytokines modulate the functions of the CNS? 2) what is the role of cytokines in the pathogenesis of neurological diseases? Thus far, it has been clearly established that cytokines can alter the functions of the CNS in specific manners, invoking CNS-controlled autonomic, neuroendocrine, and behavioral responses. Induced expression of cytokines has also been found in the CNS during brain injury and infection, contributing to the immunological processes at this "immunologically privileged" site. Furthermore, increasing evidence points to the potential involvement of cytokines in the induction and modulation of an array of neurological diseases ranging from Alzheimer's disease to chronic fatigue syndrome. Despite such progress, however, substantial obstacles remain for both the basic understanding and the potential clinical exploitation of how cytokines interact with CNS. In this review, we will attempt to synopsize the current theories and evidence regarding the answers to the above-mentioned critical questions. These issues will be reviewed not only in isolation, as most of the original reports focused on only one of the questions, but also in parallel such that inter-issue insights may be gained. 相似文献
16.
Peter Kivisto 《Ethnic and racial studies》2013,36(4):549-577
During the past decade, transnationalism has entered the lexicon of migration scholars. As with other terms used in the study of immigration and ethnicity, this concept suffers from ambiguity as a result of competing definitions that fail to specify the temporal and spatial parameters of the term and to adequately locate it vis-à-vis older concepts such as assimilation and cultural pluralism. This article offers a review and critique of the ways the term has come to be employed at the hands of key spokespersons that have articulated the most sustained theoretical rationales to date for transnationalism as a conceptual construct to account for new immigrant identities and communities. The conclusion of the essay offers in schematic form an alternative assessment of transnationalism that locates it as one potential subset of assimilation theory, rather than as an alternative to it. 相似文献
17.
The role of habitat quality in fragmented landscapes: a conceptual overview and prospectus for future research 总被引:1,自引:0,他引:1
There is increasing empirical evidence that the quality of habitat patches (determined by either habitat degradation or natural heterogeneity in the quality of habitat) plays an important role in determining species distribution patterns and in regulating spatial dynamics in fragmented landscapes. However, to date, most of the debate has focused on whether or not to include habitat variables in fragmentation studies, and we still lack general conclusions as well as standard and robust research approaches. In this paper we show how a weak conceptualization of “patch quality” and the inappropriate choice of target surrogate variables (e.g., density is often used as an indicator of patch quality) have mainly produced case-specific results, rather than general conclusions. We then identify weaknesses in the inclusion of habitat quality measurements within fragmentation studies. In particular, we focus on: (1) the lack of appropriate experimental design, outlining how few studies have actually included a gradient of habitat quality in their sample; (2) the lack of fundamental information provided (e.g., lack of standard outputs), which in turn hampers the possibility of carrying out meta-analyses. We finally synthesize available knowledge from empirical studies and highlight the different conceptual frameworks needed for patch occupancy versus patch use studies. 相似文献
18.
Testing the enemy release hypothesis: a review and meta-analysis 总被引:1,自引:0,他引:1
One of the most cited hypotheses explaining the inordinate success of a small proportion of introduced plants that become
pests is the ‘natural enemies hypothesis’. This states that invasive introduced plants spread rapidly because they are liberated
from their co-evolved natural enemies. This hypothesis had not been properly tested until recently. Previous reviews on this
topic have been narrative and vote counting in nature. In this review, we carried out quantitative synthesis and meta-analysis
using existing literature on plants and their herbivores to test the different components of the enemy release hypothesis.
We found supporting evidence in that (1) insect herbivore fauna richness is significantly greater in the native than introduced
ranges, and the reduction is skewed disproportionally towards specialists and insects feeding on reproductive parts; and (2)
herbivore damage levels are greater on native plants than on introduced invasive congeners. However, herbivore damage levels
are only marginally greater for plants in native than in introduced ranges, probably due to the small numbers of this type
of study. Studies quantifying herbivore impacts on plant population dynamics are too scarce to make conclusions for either
comparison of plants in native vs introduced ranges or of co-occurring native and introduced congeners. For future research,
we advocate that more than two-way comparisons between plants in native and introduced ranges, or native and introduced congeners
are needed. In addition, the use of herbivore exclusions to quantify the impacts of herbivory on complete sets of population
vital rates of native vs introduced species are highly desirable. Furthermore, three-way comparisons among congeners of native
plants, introduced invasive, and introduced non-invasive plants can also shed light on the importance of enemy release. Finally,
simultaneously testing the enemy release hypothesis and other competing hypotheses will provide significant insights into
the mechanisms governing the undesirable success of invasive species. 相似文献
19.
Field experiments used to explore the effects of global change drivers, such as warming and nitrogen deposition on plant productivity and species composition, have typically focused on bottom-up processes. However, both direct and indirect responses of herbivores to the treatments could result in important interactions between top-down and bottom-up effects. These interactions may be complicated by the simultaneous effects of multiple herbivore taxa. We used rodent and mollusc exclosures in the plots of a warming and N addition field experiment to examine how herbivore removal would influence plant biomass responses to the treatments. The effect of rodent exclusion on grass biomass more than doubled in response to nitrogen addition, but did not respond to warming, whereas the effect of mollusc exclusion on grass biomass increased in response to warming, but not nitrogen. In contrast, the effect of rodent exclusion on total biomass (grasses and forbs combined) increased in response to both nitrogen and warming, while the effect of mollusc exclusion on total biomass was insensitive to nitrogen and warming. In no cases were there interactions between nitrogen and warming with respect to their influence on exclosure effects. Overall, our results demonstrated substantial and variable effects of multiple herbivore taxa on plant biomass responses to warming and N addition, despite the absence of conspicuous damage to the plant canopy. These results therefore highlight the potential importance of interactions between top-down and bottom-up factors in global change field experiments. 相似文献
20.
Functional landscapes in cities: a systems approach 总被引:1,自引:0,他引:1
Erik Andersson 《Landscape and Ecological Engineering》2018,14(2):193-199
Human enterprise and endeavour increasingly influence global processes of change, from the planetary scale down to the very local. Cities are hubs of human activity, and as the places where the majority of the world’s population live we must, when looking into an uncertain future, consider how we think about urban design. Cities are densely inhabited, lived-in landscapes where human presence and perceptions are deeply enmeshed with biophysical and built infrastructures. As such, they present complex mosaics of different habitats and competing uses, ever changing in response to human and physical drivers. If designed properly, green infrastructure can contribute many important functions to a city. Efforts to strategically make use of green infrastructure can benefit considerably from a systems perspective where linkages and cross-boundary dynamics are at the very least as important as individual components. Design, planning and governance of requirements for green infrastructure also extend far beyond biophysical elements and components. Recognition of interconnections between individual green spaces, green infrastructure and the built environment, the physical environment and diverse actors, and formal and informal governance arrangements—as outlined in the four design principles in this article—is a first important step towards a more comprehensive and inclusive approach, not least to green infrastructure planning and design. 相似文献