945 resultados para human influence
Resumo:
As the world population continues to grow past seven billion people and global challenges continue to persist including resource availability, biodiversity loss, climate change and human well-being, a new science is required that can address the integrated nature of these challenges and the multiple scales on which they are manifest. Sustainability science has emerged to fill this role. In the fifteen years since it was first called for in the pages of Science, it has rapidly matured, however its place in the history of science and the way it is practiced today must be continually evaluated. In Part I, two chapters address this theoretical and practical grounding. Part II transitions to the applied practice of sustainability science in addressing the urban heat island (UHI) challenge wherein the climate of urban areas are warmer than their surrounding rural environs. The UHI has become increasingly important within the study of earth sciences given the increased focus on climate change and as the balance of humans now live in urban areas.
In Chapter 2 a novel contribution to the historical context of sustainability is argued. Sustainability as a concept characterizing the relationship between humans and nature emerged in the mid to late 20th century as a response to findings used to also characterize the Anthropocene. Emerging from the human-nature relationships that came before it, evidence is provided that suggests Sustainability was enabled by technology and a reorientation of world-view and is unique in its global boundary, systematic approach and ambition for both well being and the continued availability of resources and Earth system function. Sustainability is further an ambition that has wide appeal, making it one of the first normative concepts of the Anthropocene.
Despite its widespread emergence and adoption, sustainability science continues to suffer from definitional ambiguity within the academe. In Chapter 3, a review of efforts to provide direction and structure to the science reveals a continuum of approaches anchored at either end by differing visions of how the science interfaces with practice (solutions). At one end, basic science of societally defined problems informs decisions about possible solutions and their application. At the other end, applied research directly affects the options available to decision makers. While clear from the literature, survey data further suggests that the dichotomy does not appear to be as apparent in the minds of practitioners.
In Chapter 4, the UHI is first addressed at the synoptic, mesoscale. Urban climate is the most immediate manifestation of the warming global climate for the majority of people on earth. Nearly half of those people live in small to medium sized cities, an understudied scale in urban climate research. Widespread characterization would be useful to decision makers in planning and design. Using a multi-method approach, the mesoscale UHI in the study region is characterized and the secular trend over the last sixty years evaluated. Under isolated ideal conditions the findings indicate a UHI of 5.3 ± 0.97 °C to be present in the study area, the magnitude of which is growing over time.
Although urban heat islands (UHI) are well studied, there remain no panaceas for local scale mitigation and adaptation methods, therefore continued attention to characterization of the phenomenon in urban centers of different scales around the globe is required. In Chapter 5, a local scale analysis of the canopy layer and surface UHI in a medium sized city in North Carolina, USA is conducted using multiple methods including stationary urban sensors, mobile transects and remote sensing. Focusing on the ideal conditions for UHI development during an anticyclonic summer heat event, the study observes a range of UHI intensity depending on the method of observation: 8.7 °C from the stationary urban sensors; 6.9 °C from mobile transects; and, 2.2 °C from remote sensing. Additional attention is paid to the diurnal dynamics of the UHI and its correlation with vegetation indices, dewpoint and albedo. Evapotranspiration is shown to drive dynamics in the study region.
Finally, recognizing that a bridge must be established between the physical science community studying the Urban Heat Island (UHI) effect, and the planning community and decision makers implementing urban form and development policies, Chapter 6 evaluates multiple urban form characterization methods. Methods evaluated include local climate zones (LCZ), national land cover database (NCLD) classes and urban cluster analysis (UCA) to determine their utility in describing the distribution of the UHI based on three standard observation types 1) fixed urban temperature sensors, 2) mobile transects and, 3) remote sensing. Bivariate, regression and ANOVA tests are used to conduct the analyses. Findings indicate that the NLCD classes are best correlated to the UHI intensity and distribution in the study area. Further, while the UCA method is not useful directly, the variables included in the method are predictive based on regression analysis so the potential for better model design exists. Land cover variables including albedo, impervious surface fraction and pervious surface fraction are found to dominate the distribution of the UHI in the study area regardless of observation method.
Chapter 7 provides a summary of findings, and offers a brief analysis of their implications for both the scientific discourse generally, and the study area specifically. In general, the work undertaken does not achieve the full ambition of sustainability science, additional work is required to translate findings to practice and more fully evaluate adoption. The implications for planning and development in the local region are addressed in the context of a major light-rail infrastructure project including several systems level considerations like human health and development. Finally, several avenues for future work are outlined. Within the theoretical development of sustainability science, these pathways include more robust evaluations of the theoretical and actual practice. Within the UHI context, these include development of an integrated urban form characterization model, application of study methodology in other geographic areas and at different scales, and use of novel experimental methods including distributed sensor networks and citizen science.
Resumo:
What constitutes effective corporate governance? Which director characteristics render boards effective at positively influencing firm-level performance outcomes? This dissertation examines these questions by taking a multilevel, multidisciplinary approach to corporate governance. I explore the individual-, team-, and firm- level factors that enable directors to serve effectively as strategic resources during international expansion. I argue that directors’ international experience improves their ability to serve as effective strategic consultants and resource providers to firms during the complex internationalization process. However, unlike prior research, which tends to assume that directors with the potential to provide important resources uniformly do so, I acknowledge contextual factors (i.e. board cohesiveness, strategic relevance of directors’ experience) that affect their propensity to actually influence outcomes. I explore these issues in three essays: one review essay and two empirical essays. In the first empirical essay, I integrate resource dependence theory with insights from social-psychological research to explore the influence of board capital on firms’ cross-border M&A performance. Using a sample of cross-border M&As completed by S&P 500 firms from 2004-2009, I find evidence that directors’ depth of international experience is associated with superior pre-deal outcomes. This suggests that boards’ deep, market-specific knowledge is valuable during the target selection phase. I further find that directors’ breadth of international experience is associated with superior post-deal performance, suggesting that these directors’ global mindset helps firms in the post-M&A integration phase. I also find that these relationships are positively moderated by board cohesiveness, measured by boards’ internal social ties. In the second empirical essay, I explore the boundary conditions of international board capital by examining how the characteristics of firms’ internationalization strategy moderate the relationship between board capital and firm performance. Using a panel of 377 S&P 500 firms observed from 2004-2011, I find that boards’ depth of international experience and social capital are more important during early stages of internationalization, when firms tend to lack market knowledge and legitimacy in the host markets. On the other hand, I find that breadth of international experience has a stronger relationship with performance when firms’ have higher scope of internationalization, when information-processing demands are higher.
Resumo:
Coastal marine ecosystems are among the most impacted globally, attributable to individual and cumulative effects of human disturbance. Anthropogenic nutrient loading is one stressor that commonly affects nearshore ecosystems, including seagrass beds, and has positive and negative effects on the structure and function of coastal systems. An additional, previously unexplored mechanistic pathway through which nutrients may indirectly influence nearshore systems is by driving blooms of benthic jellyfish. My dissertation research, conducted on Abaco Island, Bahamas, focused on elucidating the role that benthic jellyfish have in structuring systems in which they are common (i.e., seagrass beds), and explored mechanistic processes that may drive blooms of this taxa. To establish that human disturbances (e.g., elevated nutrient availability) may drive increased abundance and size of benthic jellyfish, Cassiopea spp., I conducted surveys in human-impacted and unimpacted coastal sites. Jellyfish were more abundant (and larger) from human-impacted areas, positively correlated to elevated nutrient availability. In order to elucidate mechanisms linking Cassiopea spp. with elevated nutrients, I evaluated whether zooxanthellae from Cassiopea were higher from human-disturbed systems, and whether Cassiopea exhibited increased size following nutrient input. I demonstrated that zooxanthellae population densities were elevated in human-impacted sites, and that nutrients led to positive jellyfish growth. As heightened densities of Cassiopea jellyfish may exert top-down and bottom-up controls on flora and fauna in impacted seagrass beds, I sought to examine ecological responses to Cassiopea. I evaluated whether there was a relationship between high Cassiopea densities and lower benthic fauna abundance and diversity in shallow seagrass beds. I found that Cassiopea have subtle effects on benthic fauna. However, through an experiment conducted in a seagrass bed in which nutrients and Cassiopea were added, I demonstrated that Cassiopea can result in seagrass habitat modification, with negative consequences for benthic fauna. My dissertation research demonstrates that increased human-driven benthic jellyfish densities may have indirect and direct effects on flora and fauna of coastal marine systems. This knowledge will advance our understanding of how human disturbances shift species interactions in coastal ecosystems, and will be critical for effective management of jellyfish blooms.
Resumo:
Three closely related human sec14p-like proteins (hTAP1, 2, and 3, or SEC14L2, 3, and 4, respectively) have been described. These proteins may participate in intracellular lipid transport (phospholipids, squalene, tocopherol analogues and derivatives) or influence regulatory lipid-dependent events. Here, we show that the three recombinant hTAP proteins associate with the Golgi apparatus and mitochondria, and enhance the in vitro transport of radioactively labeled α-tocopherol to mitochondria in the same order of magnitude as the human α-tocopherol transfer protein (α-TTP). hTAP1 and hTAP2 are expressed in several cell lines, whereas the expression level of hTAP3 is low. Expression of hTAP1 is induced in human umbilical cord blood-derived mast cells upon differentiation by interleukin 4. In tissues, the three hTAPs are detectable ubiquitously at low level; pronounced and localized expression is found for hTAP2 and hTAP3 in the perinuclear region in cerebellum, lung, liver and adrenal gland. hTAP3 is well expressed in the epithelial duct cells of several glands, in ovary in endothelial cells of small arteries as well as in granulosa and thecal cells, and in testis in Leydig cells. Thus, the three hTAPs may mediate lipid uptake, secretion, presentation, and sub-cellular localization in a tissue-specific manner, possibly using organelle- and enzyme-specific docking sites.
Resumo:
In skin, vitamin E acts as the predominant lipophilic antioxidant with a protective function against irradiation and oxidative stress. In addition to that, vitamin E can also modulate signal transduction and gene expression. To study whether the four natural tocopherol analogues (α-, β-, γ-, δ-tocopherol) can influence transcriptional activity by modulating the activity of nuclear receptors, a human keratinocytes cell line (NCTC 2544) was transfected with plasmids containing the luciferase reporter gene under control by direct repeat elements (DR1–DR4), representing binding sites for four different classes of nuclear receptors. In this model, the tocopherols positively modulated only the reporter construct containing a consensus element for peroxisome proliferator-activated receptors (PPARs). The induction was strongest with γ-tocopherol and was most likely the direct consequence of stimulation of PPARγ protein expression in keratinocytes. Vitamin E treatment also led to increased expression of a known PPARγ target gene involved in terminal keratinocytes differentiation, the transglutaminase-1.
Resumo:
Grazing mollusks are used as a food resource worldwide, and limpets are harvested commercially for both local consumption and export in several countries. This study describes a field experiment to assess the effects of simulated human exploitation of limpets Patella vulgata on their population ecology in terms of protandry (age-related sex change from male to female), growth, recruitment, migration, and density regulation. Limpet populations at two locations in southwest England were artificially exploited by systematic removal of the largest individuals for 18 months in plots assigned to three treatments at each site: no (control), low, and high exploitation. The shell size at sex change (L50: the size at which there is a 50:50 sex ratio) decreased in response to the exploitation treatments, as did the mean shell size of sexual stages. Size-dependent sex change was indicated by L50 occurring at smaller sizes in treatments than controls, suggesting an earlier switch to females. Mean shell size of P. vulgata neuters changed little under different levels of exploitation, while males and females both decreased markedly in size with exploitation. No differences were detected in the relative abundances of sexual stages, indicating some compensation for the removal of the bigger individuals via recruitment and sex change as no migratory patterns were detected between treatments. At the end of the experiment, 0–15 mm recruits were more abundant at one of the locations but no differences were detected between treatments. We conclude that sex change in P. vulgata can be induced at smaller sizes by reductions in density of the largest individuals reducing interage class competition. Knowledge of sex-change adaptation in exploited limpet populations should underpin strategies to counteract population decline and improve rocky shore conservation and resource management.
Resumo:
Grazing mollusks are used as a food resource worldwide, and limpets are harvested commercially for both local consumption and export in several countries. This study describes a field experiment to assess the effects of simulated human exploitation of limpets Patella vulgata on their population ecology in terms of protandry (age-related sex change from male to female), growth, recruitment, migration, and density regulation. Limpet populations at two locations in southwest England were artificially exploited by systematic removal of the largest individuals for 18 months in plots assigned to three treatments at each site: no (control), low, and high exploitation. The shell size at sex change (L50: the size at which there is a 50:50 sex ratio) decreased in response to the exploitation treatments, as did the mean shell size of sexual stages. Size-dependent sex change was indicated by L50 occurring at smaller sizes in treatments than controls, suggesting an earlier switch to females. Mean shell size of P. vulgata neuters changed little under different levels of exploitation, while males and females both decreased markedly in size with exploitation. No differences were detected in the relative abundances of sexual stages, indicating some compensation for the removal of the bigger individuals via recruitment and sex change as no migratory patterns were detected between treatments. At the end of the experiment, 0–15 mm recruits were more abundant at one of the locations but no differences were detected between treatments. We conclude that sex change in P. vulgata can be induced at smaller sizes by reductions in density of the largest individuals reducing interage class competition. Knowledge of sex-change adaptation in exploited limpet populations should underpin strategies to counteract population decline and improve rocky shore conservation and resource management.
Resumo:
What is the human being? Which is its origin and its end? What is the influence of the nature in the man and what is his impact on nature? Forthe animalists, men are like other animals; freedom and rationality are not signs of superiority, nor having rights over the animals. For the ecohumanists, human beings are part of nature, but is qualitatively different and superior to animals; and is the creator of the civilization. We analyze these two ecological looks. A special point is the contribution ofecohumanists -from the first half of the Renaissance, who dealt in extenso the dignity and freedom of the human being-, of Michelangelo and finally, of Mozart, through his four insurmountable operas, which display the difficulty of physical ecology to engender so much beauty, so much wealth, so much love for the creatures and so much variety.
Resumo:
BACKGROUND: Mechanical overload of the heart is associated with excessive deposition of extracellular matrix proteins and the development of cardiac fibrosis. This can result in reduced ventricular compliance, diastolic dysfunction, and heart failure. Extracellular matrix synthesis is regulated primarily by cardiac fibroblasts, more specifically, the active myofibroblast. The influence of mechanical stretch on human cardiac fibroblasts' response to pro-fibrotic stimuli, such as transforming growth factor beta (TGFβ), is unknown as is the impact of stretch on B-type natriuretic peptide (BNP) and natriuretic peptide receptor A (NPRA) expression. BNP, acting via NPRA, has been shown to play a role in modulation of cardiac fibrosis.
METHODS AND RESULTS: The effect of cyclical mechanical stretch on TGFβ induction of myofibroblast differentiation in primary human cardiac fibroblasts and whether differences in response to stretch were associated with changes in the natriuretic peptide system were investigated. Cyclical mechanical stretch attenuated the effectiveness of TGFβ in inducing myofibroblast differentiation. This finding was associated with a novel observation that mechanical stretch can increase BNP and NPRA expression in human cardiac fibroblasts, which could have important implications in modulating myocardial fibrosis. Exogenous BNP treatment further reduced the potency of TGFβ on mechanically stretched fibroblasts.
CONCLUSION: We postulate that stretch induced up-regulation of the natriuretic peptide system may contribute to the observed reduction in myofibroblast differentiation.
Resumo:
The organizational and architectural configuration of white matter pathways connecting brain regions has ramifications for all facets of the human condition, including manifestations of incipient neurodegeneration. Although diffusion tensor imaging (DTI) has been used extensively to visualize white matter connectivity, due to the widespread presence of crossing fibres, the lateral projections of the corpus callosum are not normally detected using this methodology. Detailed knowledge of the transcallosal connectivity of the human cortical motor network has therefore remained elusive. We employed constrained spherical deconvolution (CSD) tractography - an approach that is much less susceptible to the influence of crossing fibres, in order to derive complete in-vivo characterizations of white matter pathways connecting specific motor cortical regions to their counterparts and other loci in the opposite hemisphere. The revealed patterns of connectivity closely resemble those derived from anatomical tracing in primates. It was established that dorsal premotor cortex (PMd) and supplementary motor area (SMA) have extensive interhemispheric connectivity - exhibiting both dense homologous projections, and widespread structural relations with every other region in the contralateral motor network. Through this in-vivo portrayal, the importance of non-primary motor regions for interhemispheric communication is emphasized. Additionally, distinct connectivity profiles were detected for the anterior and posterior subdivisions of primary motor cortex. The present findings provide a comprehensive representation of transcallosal white matter projections in humans, and have the potential to inform the development of models and hypotheses relating structural and functional brain connectivity.
Resumo:
An important aspect of sustainability is to maintain biodiversity and ecosystem functioning while improving human well-being. For this, the ecosystem service (ES) approach has the potential to bridge the still existing gap between ecological management and social development, especially by focusing on trade-offs and synergies between ES and between their beneficiaries. Several frameworks have been proposed to account for trade-offs and synergies between ES, and between ES and other components of social-ecological systems. However, to date, insufficient explicit attention has been paid to the three facets encompassed in the ES concept, namely potential supply, demand, and use, leading to incomplete descriptions of ES interactions. We expand on previous frameworks by proposing a new influence network framework (INF) based on an explicit consideration of influence relationships between these three ES facets, biodiversity, and external driving variables. We tested its ability to provide a comprehensive view of complex social-ecological interactions around ES through a consultative process focused on environmental management in the French Alps. We synthetized the interactions mentioned during this consultative process and grouped variables according to their overall propensity to influence or be influenced by the system. The resulting directed sequence of influences distinguished between: (1) mostly influential variables (dynamic social variables and ecological state variables), (2) target variables (provisioning and cultural services), and (3) mostly impacted variables (regulating services and biodiversity parameters). We discussed possible reasons for the discrepancies between actual and perceived influences and proposed options to overcome them. We demonstrated that the INF holds the potential to deliver collective assessments of ES relations by: (1) including ecological as well as social aspects, (2) providing opportunities for colearning processes between stakeholder groups, and (3) supporting communication about complex social-ecological systems and consequences for environmental management.
Resumo:
Human-environment connections are the subject of much study, and the details of those connections are crucial factors in effective environmental management. In a large, interdisciplinary study of the eastern Bering Sea ecosystem involving disciplines from physical oceanography to anthropology, one of the research teams examined commercial fisheries and another looked at subsistence harvests by Alaska Natives. Commercial fisheries and subsistence harvests are extensive, demonstrating strong connections between the ecosystem and the humans who use it. At the same time, however, both research teams concluded that the influence of ecosystem conditions on the outcomes of human activities was weaker than anticipated. Likely explanations of this apparently loose coupling include the ability of fishers and hunters to adjust to variable conditions, and the role of social systems and management in moderating the direct effects of changes in the ecosystem. We propose a new conceptual model for future studies that incorporates a greater range of social factors and their dynamics, in addition to similarly detailed examinations of the ecosystem itself.
Resumo:
Introduction: The raising frequency of cancer diseases is leading to a widespread application of antineoplastic drugs, thus increasing the probability of workplace surfaces contamination. Most of these drugs are classified by the International Agency for Research on Cancer as known or suspected human carcinogens. Skin absorption is the main route for antineoplastic drugs exposure in occupational settings, therefore cleaning protocols have paramount influence in surfaces contamination and, consequently, in exposure. The aim of this study was to assess surfaces contamination in a Portuguese chemotherapy unit before and during drug administration, in both preparation and administration facilities. Methods: Samples were collected by wipe-sampling from potentially contaminated surfaces selected by previous protocol observation. Samples were analyzed by HPLCDAD. Cyclophosphamide (CP), 5-fluorouracil (5FU), and paclitaxel (PTX) were used as surrogate markers for surfaces contamination for all cytotoxic drugs. Results: From the 34 samples collected before any preparation and administration activities, 41.2% were contaminated with 5-FU (4.0-84.7 ng/cm2) and 23.5% of the samples were contaminated with CP (19.8-139.6 μg/cm2). Only 2 samples presented contamination by PTX (5.9%) with a maximum value of 3.7 ng/cm2. Of the 37 samples collected during preparation and administration of antineoplastic drugs, 48.7% were contaminated with 5-FU (1.9-88.7 ng/cm2) and 24.3% with CP (12.0-93.9 μg/cm2). None of the samples showed contamination with PTX. Discussion: Data showed differences in contamination levels before and after the handling of antineoplastic drugs in preparation and in administration settings. These results point out the importance of cleaning procedures. This is well in accordance to previous studies that showed how the type of cleaning procedures and products used can be determinant for surfaces decontamination.
Resumo:
Obesity is a major challenge to human health worldwide. Little is known about the brain mechanisms that are associated with overeating and obesity in humans. In this project, multimodal neuroimaging techniques were utilized to study brain neurotransmission and anatomy in obesity. Bariatric surgery was used as an experimental method for assessing whether the possible differences between obese and non-obese individuals change following the weight loss. This could indicate whether obesity-related altered neurotransmission and cerebral atrophy are recoverable or whether they represent stable individual characteristics. Morbidly obese subjects (BMI ≥ 35 kg/m2) and non-obese control subjects (mean BMI 23 kg/m2) were studied with positron emission tomography (PET) and magnetic resonance imaging (MRI). In the PET studies, focus was put on dopaminergic and opioidergic systems, both of which are crucial in the reward processing. Brain dopamine D2 receptor (D2R) availability was measured using [11C]raclopride and µ-opioid receptor (MOR) availability using [11C]carfentanil. In the MRI studies, voxel-based morphometry (VBM) of T1-weighted MRI images was used, coupled with diffusion tensor imaging (DTI). Obese subjects underwent bariatric surgery as their standard clinical treatment during the study. Preoperatively, morbidly obese subjects had significantly lower MOR availability but unaltered D2R availability in several brain regions involved in reward processing, including striatum, insula, and thalamus. Moreover, obesity disrupted the interaction between the MOR and D2R systems in ventral striatum. Bariatric surgery and concomitant weight loss normalized MOR availability in the obese, but did not influence D2R availability in any brain region. Morbidly obese subjects had also significantly lower grey and white matter densities globally in the brain, but more focal changes were located in the areas associated with inhibitory control, reward processing, and appetite. DTI revealed also signs of axonal damage in the obese in corticospinal tracts and occipito-frontal fascicles. Surgery-induced weight loss resulted in global recovery of white matter density as well as more focal recovery of grey matter density among obese subjects. Altogether these results show that the endogenous opioid system is fundamentally linked to obesity. Lowered MOR availability is likely a consequence of obesity and may mediate maintenance of excessive energy uptake. In addition, obesity has adverse effects on brain structure. Bariatric surgery however reverses MOR dysfunction and recovers cerebral atrophy. Understanding the opioidergic contribution to overeating and obesity is critical for developing new psychological or pharmacological treatments for obesity. The actual molecular mechanisms behind the positive change in structure and neurotransmitter function still remain unclear and should be addressed in the future research.
Resumo:
Climate changes and their effects on fungal distribution and activity are aspects of concern regarding the human exposure to mycotoxins. An exhaustive search was made for papers available in scientific databases reposrting the influence that climate cchange has on fungi and mycotoxins. Also a review regarding fungal burden, collected between 2010 and 2015 in different settings, was done to support the discussion about future fungi and mycotoxins ocuupational exposure. A. flavus complex, E. graminerarum complex and F. verticilliodes were the most reported to be influenced by climate changes. We noted also that the analyzed Portuguese settings presented already an occupational problem due to their fungal burden. It will be important to know future climate changes to select what complexes/species and strains, and consequently the mycotoxins, we should consider as indicators of an occupational problem. In addition, epidemiologic studies are needed to increase knowledge about potential health effects related with the exposure to both risk factors.