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1.
In the Araceae, as in many other monocotyledons, the stem undergoes gradual thickening as successive internodes are produced. Along with this primary thickening of the stem, successive foliage leaves will be larger and often more complex. In many species, in addition to these and other gradual changes, there are abrupt changes, metamorphoses, that occur under certain conditions. Some metamorphoses are the result of endogenous cycling (e.g., Syngonium, Rhektophyllum, Philodendron linnaei), some are a response to changes in conditions in the environment, usually the gain or loss of contact with a substrate (e.g., Syngonium, Monstera, Rhodospatha, Philodendron section Pteromischum), and some occur when the plant reaches a certain level of maturity (e.g., Monstera). Some of these latter changes are associated with a transition from monopodial to sympodial growth (e.g., Philodendron, Anthurium). Metamorphosis enhances the developmental plasticity of the Araceae in two distinct ways: it allows for a more complex relationship between size and shape in the development to maturity, and it allows shoots to engage in dispersal activities and developmental holding patterns when conditions are not suitable for development to the adult form and reproduction.  相似文献   

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Invasive mould diseases, particularly aspergillosis, are important causes of morbidity and mortality in allogeneic stem cell transplant recipients. Mould spores are ubiquitous in the environment. Guidelines established by the Centers for Disease Control (CDC) and other authoritative organizations focus on approaches to reduce exposure to mould spores. These recommendations include avoidance of areas and activities expected to result in high levels of mould spores (e.g., construction, gardening) and use of specially designed units (protected environments) where additional standards (e.g., HEPA-filtered rooms) are in place to minimize mould exposure. These recommendations are based on consensus criteria and limited clinical data largely derived from single-center retrospective studies. In addition, highly immunocompromised stem cell transplant recipients are commonly managed as outpatients, where engineering standards of the inpatient protected environment are not feasible. In the absence of an outbreak with an identified environmental source (e.g., a contaminated air vent), it is not possible to reliably distinguish community-acquired from nosocomial aspergillosis. Adherence to infection control guidelines, acknowledging their limitations, combined with evidence-based targeted antifungal prophylaxis for the highest risk transplant recipients, is likely to be the most effective approach to prevent invasive mould diseases.  相似文献   

4.
Applicants in Europe are left with few options for the patent protection of hES cell-related technology.  相似文献   

5.
The development of a blood cell line originating from a pluripotent stem cell pool is modelled by a chain of multidimensional branching processes in which the sojourn times of the cells in certain resting states depend on the size of the following subpopulation. The stability of such a model is discussed qualitatively and some considerations concerning a possible malignant degeneration are presented. The behaviour of models for normal and malignant cell production are illustrated by stochastic stimulations. The model presented here describes the development of a certain line of blood cells (e.g. erythrocytes, monocytes or granulocytes) originating from the pluripotent stem cell up to the functional cell in the blood (for related models see, e.g., Rubinow and Lebowitz,J. math. Biol. 1, 87–225;Biophys. J. 16, 897–910).  相似文献   

6.
Ulrich Storz 《MABS-AUSTIN》2016,8(5):841-847
Dosage patents are one way to extend the market exclusivity of an approved drug beyond the lifetime of the patent that protects the drug as such. Dosage patents may help to compensate the applicant for the long period where the active pharmaceutical ingredient as such is already under patent prosecution, but not on the market yet, due to lengthy development and approval procedures. This situation erodes part of the time the drug is marketed under patent protection. Dosage patents filed at a later date can provide remedy for this problem. Examples of successful and unsuccesful attempts, and the reasons for the respective outcomes, are provided in this article.  相似文献   

7.
The expansion of national and international research efforts in stem cell research is increasingly paired with the trend of establishing stem cell banks and registries. In jurisdictions crossing the spectrum of restrictive to liberal stem cell policies, banks and registries are emerging as an essential resource for transnational access to quality-controlled and ethically sourced stem cell lines. In this study, we report the preliminary findings of a survey of stem cell banks participating in the International Stem Cell Forum's International Stem Cell Banking Initiative (ISCBI). The questionnaire circulated to all ISCBI members addressed both general issues surrounding research policies (e.g., national policies regulating the permissibility of conducting embryonic stem cell research (hESCR)) and, more specifically, issues relating to the governance of stem cell banking projects. The results of the questionnaire were complemented by scholarly research conducted by the authors. This article provides an overview of the current international hESC banking landscape (I). For this purpose, the policy and governance approaches adopted in the surveyed stem cell banks at the national level will be analyzed and areas of convergence and variance will be identified (II). It is beyond the scope of this paper to provide a comprehensive analysis of the wide range of possible governance approaches, policy responses, and their implications. However, we want to provide a starting point for discussion surrounding key questions and challenges as concerns provenance, access, and deposit of hESC lines (III). Finally, while our analysis is focused on research grade hESCs, the lessons to be gleaned from this examination will encourage further thought, analysis, and research into the issues raised in the banking and governance of other sources of stem cell lines (e.g., SCNT, parthenogenesis, iPs) (IV).  相似文献   

8.
The soil vapor to indoor air exposure pathway is considered in a wide number of risk-based site management programs. In screening-level assessments of this exposure pathway, models are typically used to estimate the transport of vapors from either subsurface soils or groundwater to indoor air. Published studies indicate that the simple models used to evaluate this exposure pathway often over estimate the impact for aromatic hydrocarbons (e.g., benzene, toluene, ethylbenzene, and xy-lene or BTEX), while showing reasonable agreement for estimates of chlorinated hydrocarbon impacts (e.g., PCE, TCE, DCE). Aerobic biodegradation of the petroleum hydrocarbons is most often attributed as the source of this disparity in the model/ data comparisons. This paper looks at the significance of aerobic biodegradation of aromatic hydrocarbons as part of the assessment of chemical vapor intrusion from soil or groundwater to indoor air. A review of relevant literature summarizing the available field data as well as various modeling approaches that include biodegradation is presented. This is followed by a simple modeling analysis that demonstrates the potential importance of biodegradation in the assessment of the soil vapor to indoor air exposure pathway. The paper concludes with brief discussions of other model considerations that are often not included in simple models but may have a significant impact on the intrusion of vapors into indoor air.  相似文献   

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This study investigated the response of freshwater wetland vegetation to hydrological driving factors by assessing collective vegetation variables, traits of dominant plant populations and hydrological and hydrochemical variables, repeat-sampled within wetland sites across Scotland and northern England. Sampling was conducted at 55 permanent sample stations located along 11 independent transects. Eco-hydrological interactions were investigated using a regression-based modelling approach. Facets of the water-table dynamic (e.g., level of drawdown, level of fluctuation), along with vegetation abundance (e.g., biomass, stem density) and diversity (e.g., species richness) values, were used to build predictive models. Of the models predicting vegetation characteristics, the greatest predictive power was R 2 = 0.67 (p < 0.001) for a model predicting stem density (m−2). Conversely, vegetation variables proved useful for predicting characteristics of the water-table environment. In this instance, the greatest predictive power was R 2 = 0.79 (p < 0.001) for a model predicting minimum water table level (i.e. maximum level of drawdown). The models were tested using data collected during 2000 from repeat sites and independent sites. This approach might be successfully applied for the purposes of integrated eco-hydrological management and monitoring of freshwater wetland vegetation.  相似文献   

11.
The study is based on anatomical and morphological investigations of Empetrum nigrum L. subsp. Hermaphroditum (Hagerup) Bocher, an important plant because of its value for medicine and food. Plant samples were collected from the northeastern part of Turkey. Morphological and anatomical features of various plant parts (e.g., stem, leaf, flower, and fruit) are illustrated and described in detail.  相似文献   

12.
For a long time, exotic scents from the islands of the South Pacific have universally been appreciated. Most frequently, fragrant flowers (e.g., frangipani, jasmine sambac, tiaré, pua kenikeni) are used locally for ornamental purposes such as flower garlands (leis). Despite their powerful and delightful fragrance, very few of these flowers have been commercially employed in this part of the world for perfume manufacturing. Creative perfumers are nevertheless strongly interested to better understand these fragrances and to use them, either genuine or artificially reconstituted. Analytical results on the fragrance of these flowers are reported, together with some economical considerations.  相似文献   

13.
Humans are continuously exposed to ionizing radiation throughout life from natural sources that include cosmic, solar, and terrestrial. Much harsher natural radiation and chemical environments existed during our planet’s early years. Mammals survived the harsher environments via evolutionarily-conserved gifts a continuously evolving system of stress-induced natural protective measures (i.e., activated natural protection [ANP]). The current protective system is differentially activated by stochastic (i.e., variable) low-radiation-dose thresholds and when optimally activated in mammals includes antioxidants, DNA damage repair, p53-related apoptosis of severely-damaged cells, reactive-oxygen-species (ROS)/reactive-nitrogen-species (RNS)- and cytokine-regulated auxiliary apoptosis that selectively removes aberrant cells (e.g., precancerous cells), suppression of disease promoting inflammation, and immunity against cancer cells. The intercellular-signaling-based protective system is regulated at least in part via epigenetic reprogramming of adaptive-response genes. When the system is optimally activated, it protects against cancer and some other diseases, thereby leading to hormetic phenotypes (e.g., reduced disease incidence to below the baseline level; reduced pain from inflammation-related problems). Here, some expressed radiation hormesis phenotypes and related mechanisms are discussed along with their implications for disease prevention and therapy.  相似文献   

14.
Effective conservation and management of primates depend on our ability to accurately assess and monitor populations through research. Camera traps are proving to be useful tools for studying a variety of primate species, in diverse and often difficult habitats. Here, we discuss the use of camera traps in primatology to survey rare species, assess populations, and record behavior. We also discuss methodological considerations for primate studies, including camera trap research design, inherent biases, and some limitations of camera traps. We encourage other primatologists to use transparent and standardized methods, and when appropriate to consider using occupancy framework to account for imperfect detection, and complementary techniques, e.g., transect counts, interviews, behavioral observation, to ensure accuracy of data interpretation. In addition, we address the conservation implications of camera trapping, such as using data to inform industry, garner public support, and contributing photos to large-scale habitat monitoring projects. Camera trap studies such as these are sure to advance research and conservation of primate species. Finally, we provide commentary on the ethical considerations, e.g., photographs of humans and illegal activity, of using camera traps in primate research. We believe ethical considerations will be particularly important in future primate studies, although this topic has not previously been addressed for camera trap use in primatology or any wildlife species.  相似文献   

15.
海岸线变化研究综述   总被引:17,自引:3,他引:17  
毋亭  侯西勇 《生态学报》2016,36(4):1170-1182
受全球及海岸带区域环境过程与人类活动的综合影响,海岸线发生剧烈的变化,对生态、环境及经济社会的影响不容忽视,海岸线变化相关研究因此得到普遍的关注。在讨论海岸线的定义和分类的基础上,介绍岸线信息提取的方法与技术,总结国内外海岸线变化的特征、机制与影响方面研究的进展,并指出未来研究的趋势,包括:对海岸线变化过程进行动态监测仍将是普遍关注的研究重点之一;对海岸线变化特征、规律与机理的认识已经日益深化,基于大量高精度数据和机理模型的研究已成为热点和前沿问题;针对不同的海岸带区域,聚焦海岸线变化的原因和机制及其对环境和生态的影响,以及不同区域之间的相互联系与影响特征,这将是未来研究的重点之一;中国海岸线变化的独特性、复杂性突出,促进和支撑中国的海岸带综合管理实践,提高决策者与管理者对岸线变化所带来的灾害风险的重视,为中国海岸带的科学规划与发展提供依据,这应该是我国海岸线变化研究的重要目标。  相似文献   

16.
Analytical methods for marker compounds formed during post-translational modifications of proteins are reviewed. Only adducts arising either in vivo or under in vitro conditions simulating the in vivo situations are discussed. All of these compounds stem from either the reaction of free amino groups (i.e., lysine, arginine or N-terminal amino acid). In most cases the reactive counterpart is an aldehydic moiety containing endogenous compound; however, other functional groups containing metabolites are considered as well. The main demand put upon such marker compounds is that they are stable in acid or enzymatic hydrolysis or, alternatively, can be stabilized by simple sample pretreatment (e.g., by reduction). Practically all categories of separation procedures can be applied provided that the chemical characteristics of a particular marker are adequately respected; frequently combination of two different separation procedures based on different principles must be used. Because of the low level of such marker compounds under in vivo conditions, an appropriate sample enrichment step must be involved. Emphasis is put upon the analysis of Amadori products, pentosidine (and pentosidine related compounds), pyrraline, furosine, N-carboxymethylamino acids, amino acid hydantoins and stabilized dicarbonyl intermediates  相似文献   

17.
Hosono  Tatsuo  Nouchi  Isamu 《Plant and Soil》1997,195(1):65-73
Ebullition of gas bubbles from the soil surface is, in some cases (e.g., in early growth stage of rice), one of the major pathways for methane transport from rice paddies to the atmosphere. However, the role of the gas phase (entrapped gas) in the paddy soil in plant-mediated methane transport, which is the major pathway for methane emission, has not been clarified. To clarify the effect of the gas phase below ground on the methane emission rate through rice plants, we partly exposed the root and stem base of hydroponically grown rice to a high concentration of methane gas at various gas pressures, and immersed the rest of the roots in a solution with a high methane concentration. The methane emission rate was measured from the top of the rice plant using a flow-through chamber method. The methane emission rate drastically increased with a small increase in gas pressure in the gas phase at the root and stem base zone, with about a 3 times larger emission rate being observed with 10 × 10-3 atm of extra pressure (corresponding to 10 cm of standing water in rice paddy) compared to no extra pressure. However, when alginate was applied to the stem near the base to prevent contact with the gas phase, the methane emission rate did not increase with increasing gas pressure. On the other hand, from observations in the rice paddy, it was found that the gas is entrapped near the surface (e.g., at a depth of 1 cm) and the gas entrapped in the soil would come into direct contact with a part of the stem near the base of the rice plant. Thus, the gas entrapped in the soil could enter into the rice body directly from the part of the stem near the base which is beneath the soil surface due to gas pressure in the gas phase resulting from the pressure exerted by the standing water. Hence, this mechanism involving the entrapped gas could play an important role in methane emission from rice paddy by affecting the plant-mediated methane transport as well as ebullition of gas bubbles.  相似文献   

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19.
Lenoir N 《Comptes rendus biologies》2003,326(10-11):1127-1134
Patent law has relied in part on ethical considerations since its inception in Europe. Such considerations have been introduced more recently in the United States. Whereas the EU Directive on the protection on the occasion of the Human Genome Project of biotechnological inventions was intended to foster economic development in Europe, its implementation is outweighted by controversy about patenting life and commercialization of science. The confusion created must be cleared at the international level through harmonization of patent office policies preventing abusive commercial practices in the absence of inventiveness.  相似文献   

20.
Verhoff  F. H.  Melfi  D. A.  Yaksich  S. M. 《Hydrobiologia》1982,91(1):241-252
Human activities generate many pollutants from different land uses. These pollutants include nutrients (e.g., phosphorus and nitrogen), toxic substances (e.g., heavy metals and pesticides), and other substances (e.g., chlorides and salts). These materials often enter a river at some upstream point and are transported downstream by the flowing water. Many substances are transported both during storms and during normal river flow and often the major portion of the transport occurs during the storms. This paper considers the quantification of transport primarily during storms. First, the characteristics of storm transport are discussed. Then, a calculation method for estimating the distance of travel for sediment related materials is presented. Third, a technique to estimate the amount of a given chemical passing a point in a stream over a specified period of time is presented. The last part of this paper contains a technique for tracing the movement of substances through a river network. In particular, this procedure yields information as to the source of given pollutants over the entire Storm period. West Virginia University  相似文献   

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