Distribution by Scientific Domains
Distribution within Life Sciences

Kinds of Natural

  • various natural

  • Terms modified by Natural

  • natural ability
  • natural abundance
  • natural aging
  • natural alkaloid
  • natural alternative
  • natural amino acids
  • natural antibody
  • natural antioxidant
  • natural area
  • natural assemblage
  • natural assumption
  • natural attenuation
  • natural barrier
  • natural behavior
  • natural bond orbital
  • natural bond orbital analysis
  • natural bone
  • natural bone mineral
  • natural breeding
  • natural candidate
  • natural capital
  • natural cause
  • natural change
  • natural channel
  • natural character
  • natural cinchona alkaloid
  • natural clay
  • natural colonization
  • natural community
  • natural component
  • natural compound
  • natural condition
  • natural connection
  • natural consequence
  • natural content
  • natural context
  • natural convection
  • natural counterpart
  • natural course
  • natural cytotoxicity receptor
  • natural death
  • natural density
  • natural dentition
  • natural development
  • natural diet
  • natural disaster
  • natural disease
  • natural distribution
  • natural disturbance
  • natural dye
  • natural dynamics
  • natural ecosystem
  • natural endowment
  • natural enemy
  • natural environment
  • natural environmental gradient
  • natural estrogens
  • natural event
  • natural evolution
  • natural example
  • natural experiment
  • natural exposure
  • natural extension
  • natural extracellular matrix
  • natural extract
  • natural factor
  • natural fermentation
  • natural fiber
  • natural fire
  • natural flavonoid
  • natural flow
  • natural flow regime
  • natural food
  • natural forest
  • natural form
  • natural frequency
  • natural function
  • natural gas
  • natural gas future
  • natural gas market
  • natural gas price
  • natural generalization
  • natural genetic transformation
  • natural genetic variation
  • natural gradient
  • natural grassland
  • natural group
  • natural growth
  • natural habitat
  • natural hazard
  • natural health products
  • natural history
  • natural history collection
  • natural history museum
  • natural history study
  • natural host
  • natural host plant
  • natural hosts
  • natural hybridization
  • natural hydrological regime
  • natural immune response
  • natural increase
  • natural infection
  • natural infections
  • natural inhabitant
  • natural inhibitor
  • natural killer
  • natural killer cell
  • natural killer cell activity
  • natural killer cell cytotoxicity
  • natural killer cell function
  • natural killer cell receptor
  • natural killer lymphoma
  • natural killer t cell
  • natural kind
  • natural laboratory
  • natural lake
  • natural landscapes
  • natural language
  • natural languages
  • natural law
  • natural law theory
  • natural level
  • natural ligand
  • natural light
  • natural logarithm
  • natural material
  • natural mating
  • natural mechanism
  • natural medicine
  • natural menopause
  • natural microbial community
  • natural microflora
  • natural mixture
  • natural molecule
  • natural monopoly
  • natural mortality
  • natural mortality rate
  • natural nest
  • natural occurrence
  • natural oil
  • natural orbital
  • natural organic matter
  • natural orifice
  • natural orifice transluminal endoscopic surgery
  • natural origin
  • natural outbreak
  • natural park
  • natural part
  • natural pasture
  • natural pattern
  • natural peptide
  • natural phenolic compound
  • natural phenomenoN
  • natural phenomenon
  • natural philosophy
  • natural photoperiod
  • natural pigment
  • natural plant
  • natural plant community
  • natural plant population
  • natural pollination
  • natural polymer
  • natural polysaccharide
  • natural pond
  • natural population
  • natural population analysis
  • natural process
  • natural product
  • natural product synthesis
  • natural productivity gradient
  • natural products
  • natural progression
  • natural property
  • natural protein
  • natural rainfall
  • natural range
  • natural rate
  • natural raw material
  • natural recovery
  • natural recruitment
  • natural regeneration
  • natural region
  • natural regulatory t cell
  • natural reinforcer
  • natural remanent magnetization
  • natural reservoir
  • natural resistance
  • natural resource
  • natural resource management
  • natural resources
  • natural response
  • natural reward
  • natural rubber
  • natural rubber blend
  • natural rubber composite
  • natural rubber latex
  • natural sample
  • natural scene
  • natural science
  • natural sediment
  • natural selection
  • natural setting
  • natural site
  • natural soil
  • natural source
  • natural spawning
  • natural stand
  • natural state
  • natural stimulus
  • natural stock
  • natural strain
  • natural stream
  • natural stressor
  • natural structure
  • natural substance
  • natural substrate
  • natural succession
  • natural sunlight
  • natural surface
  • natural surfactant
  • natural system
  • natural target
  • natural theology
  • natural therapy
  • natural tooth
  • natural toxin
  • natural tracer
  • natural transformation
  • natural trap
  • natural treg
  • natural tropism
  • natural unemployment rate
  • natural variability
  • natural variation
  • natural vegetation
  • natural ventilation
  • natural water
  • natural water sample
  • natural way
  • natural wetland
  • natural world

  • Selected Abstracts


    EVOLUTION, Issue 5 2004
    Maria R. Servedio
    Abstract Although reinforcement is ostensibly driven by selection against hybrids, there are often other components in empirical cases and theoretical models of reinforcement that may contribute to premating isolation. One of these components is local adaptation of a trait used in mate choice. I use several different comparisons to assess the roles that local adaptation and selection against hybrids may play in reinforcement models. Both numerical simulations of exact recursion equations and analytical weak selection approximations are employed. I find that selection against hybrids may play a small role in driving preference evolution in a reinforcement model where the mating cue is separate from loci causing hybrid incompatibilities. When females have preferences directly for purebreds of their own population, however, selection against hybrids can play a large role in premating isolation evolution. I present some situations in which this type of selection is likely to exist. This work also illustrates shortfalls of using a weak selection approach to address questions about reinforcement. [source]


    EVOLUTION, Issue 3 2003
    Brian D. Inouye
    No abstract is available for this article. [source]


    ABSTRACT. Four rock types (quartz mica gneiss, schist, quartzite and calc-silicate) located in the Satluj and Alaknanda valleys were used to test whether a Schmidt hammer can be used to distinguish rock surfaces affected by various natural and man-induced processes like manual smoothing of rock surfaces by grindstone, surface weathering, deep weathering, fluvial polishing and blasting during road construction. Surfaces polished by fluvial process yielded the highest Schmidt hammer rebound (R-) values and the blast-affected surfaces yielded the lowest R-values for the same rock type. Variations in R-value also reflect the degree of weathering of the rock surfaces. It has been further observed that, for all the rock types, the strength of relationship between R-values for the treated surfaces (manual smoothing of rock surface by grindstone) and the unconfined compressive strength (UCS) is higher than for the fresh natural surfaces. [source]


    RATIO, Issue 3 2009
    John Hacker-Wright
    Philippa Foot's Natural Goodness is in the midst of a cool reception. It appears that this is due to the fact that Foot's naturalism draws on a picture of the biological world at odds with the view embraced by most scientists and philosophers. Foot's readers commonly assume that the account of the biological world that she must want to adhere to, and that she nevertheless mistakenly departs from, is the account offered by contemporary neo-Darwinian biological sciences. But as is evident in her notion of function, Foot does not employ an evolutionary view of the biological world. I will attempt to show, first, that it is for good reason that Foot is not operating with an evolutionary view of function; her views do not aim to unseat evolutionary views of function, but instead simply have quite different theoretical goals. Second, I aim to underline the importance to Foot's naturalism of the fact that we are practically reasoning creatures. The profundity of Foot's ethical naturalism rests in how she approaches our nature as practically reasoning creatures. In this aspect of Foot's thought, there is a significant Kantian strain that is surprising to find in someone who calls herself an ethical naturalist.1 [source]


    BIOETHICS, Issue 7 2007
    ABSTRACT A recent approach for bioterrorism risk management calls for stricter regulations over biotechnology as a way to control subversion of technology that may be used to create a man-made pandemic. This approach is largely unworkable given the increasing pervasiveness of molecular techniques and tools throughout society. Emerging technology has provided the tools to design much deadlier pathogens but concomitantly the ability to respond to emerging pandemics to reduce mortality has also improved significantly in recent decades. In its historical context determining just how ,risky' biological weapons is an important consideration for decision making and resource allocation. Management should attempt to increase capacity, share resources, provide accurate infectious disease reporting, deliver information transparency and improve communications to help mitigate the magnitude of future pandemics. [source]

    Cardiac autonomic function and baroreflex changes following 4 weeks of resistance versus aerobic training in individuals with pre-hypertension

    ACTA PHYSIOLOGICA, Issue 3 2009
    S. R. Collier
    Abstract Aim:, Cardiac autonomic modulation and baroreflex sensitivity (BRS) are altered in individuals with hypertension. Aerobic exercise (AE) training has been shown to improve both measures, yet little is known about the effects of resistance exercise (RE). The purpose of this study was to examine the heart rate variability (HRV) and BRS following 4 weeks of resistance or aerobic training in a population with borderline high blood pressure (BP). Methods:, Twenty-nine mild hypertensives were recruited and randomly assigned to 4 weeks of RE or AE training. Before and after training, resting measures of HRV frequencies and BRS were obtained. Results:, There was a significant decrease in resting systolic BP for both exercise training modes (RE 136 ± 3.0 pre- to 132 ± 3.4 post-training vs. AE 142 ± 4.0 pre- to 137 ± 3.6 mmHg post-training, P = 0.019). Diastolic BP decreased significantly following both exercise training modes (RE 78 ± 1.31 pre to 74 ± 1.1 post vs. AE 80 ± 1.7 pre to 77 ± 1.6 mmHg post, P = 0.002). A significant time by training mode interaction for low frequency : high frequency (HF) ratio (P = 0.017) with AE decreasing the ratio (275.21 ± 67.28 to 161.26 ± 61.49) and RE increasing this ratio (143.73 ± 65.00 to 227.83 ± 59.41). Natural log-transformed (ln) HRV values showed a time-by-training mode interaction for ln HF (P = 0.05) as ln HF increased (4.7 ± 0.38 to 5.4 ± 0.35 ms2) following AE and decreased (5.98 ± 0.37 to 5.76 ± 0.42 ms2) following RE. BRS increased following aerobic training and decreased after resistance training (6.74 ± 1.2 to 7.94 ± 1.3 and 10.44 ± 1.2 to 9.1 ± 1.2 ms mmHg,1 respectively, P = 0.021). Conclusions:, Aerobic exercise improved the autonomic nervous system (increasing vagal tone, reducing sympathovagal balance while increasing BRS) while RE showed no improvements in cardiac autonomic tone and decreased BRS. [source]

    Constructing Vulnerability: The Historical, Natural and Social Generation of Flooding in Metropolitan Manila

    DISASTERS, Issue 3 2003
    Greg Bankoff
    Flooding is not a recent hazard in the Philippines but one that has occurred throughout the recorded history of the archipelago. On the one hand, it is related to a wider global ecological crisis to do with climatic change and rising sea levels but on the other hand, it is also the effect of more localised human activities. A whole range of socio-economic factors such as land use practices, living standards and policy responses are increasingly influencing the frequency of natural hazards such as floods and the corresponding occurrence of disasters. In particular, the reason why flooding has come to pose such a pervasive risk to the residents of metropolitan Manila has its basis in a complex mix of inter-relating factors that emphasise how the nature of vulnerability is constructed through the lack of mutuality between environment and human activity over time. This paper examines three aspects of this flooding: first, the importance of an historical approach in understanding how hazards are generated; second, the degree of interplay between environment and society in creating risk; and third, the manner in which vulnerability is a complex construction. [source]

    Natural and accidental torsion in one-storey structures on elastic foundation under non-vertically incident SH-waves

    Javier Avilés
    Abstract Factors , and , used in equivalent static analysis to account for natural and accidental torsion are evaluated with consideration of soil,structure interaction. The combined torsional effects of structural asymmetry and foundation rotation are examined with reference to a single monosymmetric structure placed on a rigid foundation that is embedded into an elastic half-space, under to the action of non-vertically incident SH waves. Dynamic and accidental eccentricities are developed such that when used together with the code-specified base shear, the resulting static displacement at the flexible edge of the building is identical to that computed from dynamic analysis. It is shown that these eccentricities do not have a unique definition because they depend on both the selection of the design base shear and the criterion used for separation of the torsional effects of foundation rotation from those of structural asymmetry. Selected numerical results are presented in terms of dimensionless parameters for their general application, using a set of appropriate earthquake motions for ensuring generality of conclusions. The practical significance of this information for code-designed buildings is elucidated. Copyright © 2006 John Wiley & Sons, Ltd. [source]

    NMR Investigation of the Bound Conformation of Natural and Synthetic Oligomannosides to Banana Lectin

    Caroline Clavel
    Abstract The conformational behaviour of three mannose-containing oligosaccharides, namely, the ,1,3[,1,6] trisaccharide, a heptasaccharide with ,1,2, ,1,3 and ,1,6 linkages and a tetrasaccharide consisting of ,1,3 and ,1,2 linkages, when bound to banana lectin (BanLec) has been evaluated by trNOE NMR methods and docking calculations. It was found that the molecular recognition event involves a conformational selection process with only one of the conformations present in the free state of the sugar being recognised at the lectin binding site. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

    Population dynamics and stock status of cobia, Rachycentron canadum, caught in Australian recreational and commercial coastal fisheries

    G. C. FRY
    Abstract, Age and growth of Rachycentron canadum (L.) was studied in northern and eastern Australia to provide data for a preliminary assessment of the stock and to explore possible fisheries management strategies using minimum legal lengths. Fish collected from commercial and recreational fisheries ranged in size and weight from 125 to 1633 mm fork length (FL) and 0.031 to 55 kg respectively. Annual growth increments in sectioned otoliths formed by November,December. Estimated ages ranged from 0 to 7 yr for both genders. Longevity was estimated to be at least 13 yr. Von Bertalanffy growth function parameters were L = 1160 mm FL, K = 0.63 yr,1 and t0 = ,0.21 yr,1. Rachycentron canadum reach 600 mm FL in their first year and over 1000 mm FL in 3 years. Natural and total mortalities were estimated at 0.35 yr,1 and 0.85 yr,1, respectively. Populations of R. canadum may be vulnerable to growth overfishing under the current minimum legal length of 750 mm total length (TL) in Queensland waters. An increase in minimum legal length to 850 mm TL is recommended. [source]

    Origin of post-Minoan caves and volcaniclastic cave fill, Thera (Santorini), Greece

    Joan M. Ramage
    The Aegean island of Thera (Santorini) was covered by tephra from its cataclysmic Late Bronze Age (ca. 3600 yr B.P.) eruption. Vertical exposures of the eruptive sequence show secondary, nonvolcanic, circular (in cross section) features composed of stratified sediment. Many are inaccessible from the floors of modern quarries and appear to be caves filled with younger sediment, but show no connection to the land surface. A filled cave was found in the wall of a modern gully outside the modern quarries, and a filled cave was found in a terrace scarp, well above the modern gully. Natural (and probably rapid) incision by gullies into the thick tephra deposit left many locations with lateral access to tephra. Inhabitants from post-Minoan to recent times excavated tephra for materials and buildings, and caves were subsequently filled by sporadic (possibly seasonal) flood events that deposited sediment. These gullies may have provided access for modern tephra removal that isolated the filled caves high on the modern quarry walls. © 2003 Wiley Periodicals, Inc. [source]

    Cover Picture: Assembly of Wiseana Iridovirus: Viruses for Colloidal Photonic Crystals (Adv. Funct.

    Abstract Assembly of colloids is a versatile tool for micro- and nanofabrication. Natural and artificially engineered viruses offer the opportunity to expand the functionality and versatility of such assemblies. The cover shows optically iridescent, thin polycrystalline arrays (background) as well as bulk pellets (inset right) that exhibit reversible hydration-dependent reflection spectra, as reported by Vaia and co-workers on p.,1086. The films and pellets were created in vitro with classical colloid-assembly techniques from Wiseana iridescent virus (inset, center) harvested from infected Wiseana spp larvae (inset, left). In,vitro assembly of Wiseana iridescent virus (WIV) yields iridescent pellets and films with structural color more vivid than in the native insect. WIV is icosahedral in shape, 140,nm in diameter, with 30,nm long fibrils attached to the outer surface, and exhibits a surface charge ca.,1/6th that of a comparable polymer colloid. The low surface charge and tethered chains on the virus surface allow the facile modification of the interparticle distance. Directed sedimentation yields predominantly an amorphous liquid-like packing of the virus. Such samples exhibit a broad reflection band that is angle independent and for which the broad maximum can be reversibly shifted from blue towards red with increased hydration. Slow sedimentation and flow-assisted assembly methods produce thin films with a polycrystalline morphology that exhibit narrower, more intense reflectivity peaks, which are hydration and angle dependent. This study points toward the potential of viral particles for photonic crystals where their unique structural features (icosahedral symmetry, extreme monodispersity, precise surface functionalization, and tethered surface chains of low surface-charge density) may lead to superior control of optical properties of their assembled arrays. [source]

    Will only an earthquake shake up economics?

    Ronald SCHETTKAT
    Abstract. "Natural rate theory", the Efficient Market Hypothesis and its labour market application dominated interpretations of economic trends and policy prescriptions from the 1970s onwards, with their views of public policy and regulation as distorting otherwise well-functioning free markets. The upheaval of the current crisis is shaking these theories to the core. In this context, Schettkat examines European experience from the 1990s onwards and shows the theories to be unsubstantiated: high unemployment persisted post-recession despite structural reforms to labour market institutions, and the resumption of economic growth was hindered by then-dominant deflationary monetary and fiscal policies inspired by these theories. [source]

    Isolation and selection of Bacillus spp. as potential biological agents for enhancement of water quality in culture of ornamental fish

    R. Lalloo
    Abstract Aims:, To isolate, select and evaluate Bacillus spp. as potential biological agents for enhancement of water quality in culture of ornamental fish. Methods and Results:, Natural isolates obtained from mud sediment and Cyprinus carpio were purified and assessed in vitro for efficacy based on the inhibition of growth of pathogenic Aeromonas hydrophila and the decrease in concentrations of ammonium, nitrite, nitrate and phosphate ions. Based on suitability to predefined characteristics, the isolates B001, B002 and B003 were selected and evaluated in vitro in the presence of Aer. hydrophila and in a preliminary in vivo trial with C. carpio. The inhibitory effect on pathogen growth and the decrease in concentrations of waste ions was demonstrated. Based on 16S RNA sequence homology, the isolates were identified as Bacillus subtilis, Bacillus cereus and Bacillus licheniformis, respectively. Isolate B002 did not contain the anthrax virulence plasmids pOX1, pOX2 or the B. cereus enterotoxin. Conclusions:, Selected isolates effected synergistic reduction in pathogen load and the concentrations of waste ions in vitro and in vivo and are safe for use in ornamental aquaculture. Significance and Impact of the Study:, A new approach for assessment of biological agents was demonstrated and has yielded putative isolates for development into aquaculture products. [source]

    Insights into the processing of carbon in the South Florida Cypress Wetlands: a whole-ecosystem approach using network analysis

    Cristina Bondavalli
    Abstract Aim The aim of this research was to investigate the potential of the South Florida Cypress Wetlands as a carbon-accumulating system. Location This ecosystem is part of the Big Cypress Natural Preserve, located in the south-west part of Florida (USA) between the Mangrove Swamps that border the Gulf of Mexico and the Everglades. Methods This investigation was carried out by constructing networks of carbon exchange between the living and nonliving components that comprise this ecosystem. By means of these networks potential for carbon accumulation has been assessed by identifying and quantifying pathways for the transfer of carbon, assessing the efficiency between trophic levels, and evaluating the importance of material cycling. These analyses are commonly referred to as network analysis. Results Results obtained show that dependency on detritus by higher trophic levels is rather low and so is the trophic efficiency. Yet, less than 10% of the carbon that flows through the system is recycled and the magnitude of internal ascendency reaches only 40% of the total system ascendency. Main,conclusions All these results support the hypothesis that the South Florida Cypress Wetlands are predominately flow-through in nature and that carbon accumulation in this environment is noticeable. [source]

    Ethical issues in biotechnologies and international trade

    Joseph H Hulse
    Natural and physical sciences are based on determinable facts. What is ethical, as distinct from illegal, is largely a matter of opinion. Scientific and industrial activities related to ancient and modern biotechnologies are among the most critically scrutinised for ethical probity by social activists and journalists. The practices and products of biotechnologies should be judged both deontologically , by motivation and intention, and teleologically , by determinable consequence. Bioethical criteria have been proposed by governments, medical practitioners and philosophers for many centuries. During the past decade, various scientifically competent organisations, national and international, have formulated comprehensive protocols by which to determine effectiveness and safety of novel foods, pharmaceuticals and other biologicals, including those derived from genetically modified organisms. Means and opportunities by which to satisfy the health and nutritional needs of impoverished nations and communities differ significantly from those who enjoy greater affluence. It is distinctly unethical for Europeans and North Americans, whose food and health securities are not at risk, to impose their ethical predilections on poorer nations. Equally reprehensible are the diverse tariff and non-tariff barriers to equitable international trade, and acts of biopiracy inflicted upon poorer nations. As a wise Asian sage has observed, the planet's resources and scientific ingenuity are sufficient to satisfy everyone's need, but not everyone's greed. Present and predictable world-wide demand for bioscientists and bioengineers exceeds best estimates of supply. Systematically planned, long-term investments by governments and bioindustries to generate adequate qualified men and women are urgently needed. © 2002 Society of Chemical Industry. [source]


    ABSTRACT Natural ,-amylase and ,-glucosidase inhibitors from food-grade plants offer an attractive strategy to manage postprandial hyperglycemia for type 2 diabetes management via control of starch breakdown and intestinal glucose absorption. In this study, four random sources of red and white wines as well as four types of teas were investigated for ,-amylase and ,-glucosidase inhibitory potential. Water extracts of black tea had the highest ,-glucosidase inhibitory activity, followed by white tea and oolong tea. All the randomly selected red wines had significant ,-glucosidase inhibitory activity compared to white wine. The ,-glucosidase inhibitory activity of the tea and wines correlated to the phenolic content, antioxidant activity and phenolic profile of the extracts. Further, these extracts had less or no ,-amylase inhibitory activity, indicating potential to overcome the side effects of undigested starch. This research has relevance for managing hyperglycemia and related oxidation-linked dysfunction and concurrently reducing problems of undigested starch. PRACTICAL APPLICATIONS In this study anti-diabetic-relevant potential of wines and teas were confirmed in four types of red and white wines as well as four types of commonly available teas using in vitro enzyme assays for alpha-glucosidase and alpha-amylase inhibitory activities. In vitro inhibitory activities of these enzymes provide a strong biochemical rationale for further in vivo studies and dietary management strategy for type 2 diabetes through the control of glucose absorption. Further this phenolic antioxidant-enriched dietary strategy using specific beverage combinations can generate a whole food profile that has the potential to reduce hyperglycemia-induced pathogenesis and also associated complications linked to cellular oxidation stress. [source]

    Comparison of Natural and Artificial Aging of Ballpoint Inks

    Claudia Berger-Karin
    Abstract:, Solvent evaporation caused by aging from ballpoint inks was measured by gas chromatography/mass spectroscopy (GC/MS). The sample preparation was carried out with two different thermal desorption systems. The results are compared. Thirteen inks were classified with regard to their solvents, polymers, and additives. The variation of the aforementioned compounds caused by aging was monitored for naturally and artificially aged samples. In this paper, the results are compared and discussed with respect to forensic casework. [source]

    Book News: Microthermal Field-Flow Fractionation: Analysis of Synthetic, Natural, and Biological Macromolecules and Particles.

    Edited by Josef Janca

    Water use (and abuse) and its effects on the crater-lakes of Valle de Santiago, Mexico

    Javier Alcocer
    Abstract Most Mexicans live in the arid and semiarid regions that represent two-thirds of the Mexican territory, where water is scarce. Natural, as well as human, causes are favouring the degradation of Mexican lakes. There is a clear need to develop and implement sustainable water-use programmes at a catchment scale. However, the accelerated degradation rate of the Mexican lakes means that there will not be enough time to perform whole-basin evaluations to establish sustainable water-use programmes before the lakes dry up. The case of the Valle de Santiago crater-lakes clearly illustrates the declining trend that Mexican inland aquatic resources follow. Vegetation clearance, overgrazing, abatement of phreatic waters and salinization have induced severe erosion and overall desertification (land degradation) in the basin for what, it seems, a long time (i.e. prehispanic times). In this way, human activities could be provoking at least the following negative consequences: a hotter and drier local climate, water scarcity, dust storms and soil salinization. The aquatic (surface and groundwater) resources of the Valle de Santiago basin have been seriously threatened. Two of the four crater-lakes have already dried up and phreatic mantle abatement reaches up to 2.5 m per year. In spite of these facts, no sustainable water-use programme has been established yet. The future scenery of this Mexican basin looks alarmingly like many other basins in the central and northern Mexican territories. [source]

    Explaining the "Natural Order of L2 Morpheme Acquisition" in English: A Meta-analysis of Multiple Determinants

    LANGUAGE LEARNING, Issue S1 2005
    Jennifer M. Goldschneider
    This meta-analysis pools data from 25 years of research on the order of acquisition of English grammatical morphemes by students of English as a second language (ESL). Some researchers have posited a "natural" order of acquisition common to all ESL learners, but no single cause has been shown for this phenomenon. Our study investigated whether a combination of 5 determinants (perceptual salience, semantic complexity, morphophonological regularity, syntactic category, and frequency) accounts for the variance in acquisition order. Oral production data from 12 studies, together involving 924 participants, were pooled to obtain weighted accuracy scores for each of 6 grammatical functors. Results of a multiple-regression analysis showed that a large portion of the total variance in acquisition order was explained by the combination of the 5 determinants. Several of these determinants, it was argued, can be seen as part of a broad conceptualization of salience. Since the article was originally published, a number of meta-analyses have appeared in the applied linguistics literature (e.g., Masgoret & Gardner, 2003; Norris & Ortega, 2000; Ortega, 2003), and a book on meta-analysis in applied linguistics research is forthcoming (Norris & Ortega, in press). Meanwhile, research on the acquisition of Hebrew as a second language has begun to provide cross-linguistic evidence for how different aspects of salience contribute to ease or difficulty of second language acquisition (DeKeyser, Alfi-Shabtay, Ravid, & Shi, 2005) and how salience interacts with age of learning (DeKeyser, Ravid, & Alfi-Shabtay, 2005). [source]

    Explaining the "Natural Order of L2 Morpheme Acquisition" in English: A Meta-analysis of Multiple Determinants

    LANGUAGE LEARNING, Issue 1 2001
    Jennifer M. Goldschneider
    Some researchers have posited a &;ldquo;natural&;rdquo; order of acquisition of English grammatical morphemes common to all learners of English as a second language, but no single cause has been shown for this phenomenon. This meta-analysis investigated whether a combination of five determinants (perceptual salience, semantic complexity, morphophonological regularity, syntactic category, and frequency) accounts for a large part of the total variance found in acquisition order. Oral production data from 12 studies over almost 25 years, together involving 924 subjects, were pooled. Multiple regression analysis showed that a very large portion of the total variance in acquisition order is explained by the combination of the five determinants. We suggest research on other potential contributing factors and discuss the need for similar research in other languages. [source]

    Aminopeptidase-N/CD13 (EC inhibitors: Chemistry, biological evaluations, and therapeutic prospects

    Brigitte Bauvois
    Abstract Aminopeptidase N (APN)/CD13 (EC is a transmembrane protease present in a wide variety of human tissues and cell types (endothelial, epithelial, fibroblast, leukocyte). APN/CD13 expression is dysregulated in inflammatory diseases and in cancers (solid and hematologic tumors). APN/CD13 serves as a receptor for coronaviruses. Natural and synthetic inhibitors of APN activity have been characterized. These inhibitors have revealed that APN is able to modulate bioactive peptide responses (pain management, vasopressin release) and to influence immune functions and major biological events (cell proliferation, secretion, invasion, angiogenesis). Therefore, inhibition of APN/CD13 may lead to the development of anti-cancer and anti-inflammatory drugs. This review provides an update on the biological and pharmacological profiles of known natural and synthetic APN inhibitors. Current status on their potential use as therapeutic agents is discussed with regard to toxicity and specificity. © 2005 Wiley Periodicals, Inc. Med Res Rev [source]

    Evidence for allergen-specific IgE of maternal origin in human placenta

    ALLERGY, Issue 6 2009
    M. Joerink
    Background:, Immunoglobulin E (IgE) has been identified on macrophage-like cells in the villi of human placenta, irrespective of the serum IgE levels or allergy status of the mother. The origin of placental IgE is debated and it is not known if it is spontaneously produced, so-called ,natural IgE', or if it has any specificity for certain allergens. The aim of this study was to investigate if placental IgE originates from mother or child and to analyse its specificity. Methods:, Immunoglobulin E was eluted from placenta by lowering the pH. Total and allergen-specific IgEs were measured in placenta eluate, maternal and cord blood plasma by means of ImmunoCAP (Phadia AB). The levels of natural antibodies were determined with an anti-phosphorylcholine (PC) enzyme-linked immunosorbent assay, as natural IgE has been shown in one previous publication with this assay. Results:, Detectable amounts of IgE were eluted from 11/12 full-term placentas. Natural (anti-PC) IgE antibodies were detected in low amounts in maternal plasma but not in the placental eluate or in cord blood plasma. There was a significant correlation between the amount of total IgE eluted from placenta and the levels of total IgE in maternal plasma; however, not between maternal and cord blood plasma. Allergen-specific IgE was only found in placental eluates from mothers with specific IgE towards these allergens. Furthermore, there was a significant correlation between the amount of allergen-specific IgE eluted from placenta and the levels of allergen-specific IgE in maternal plasma. Allergen-specific IgE could not be detected in cord blood. Conclusion:, These results suggest a maternal origin of placental IgE, which can be allergen-specific. [source]

    Direct analysis of single leaf disks for chemopreventive glucosinolates

    Qiaomei Wang
    Abstract Natural isothiocyanates, produced during plant tissue damage from methionine-derived glucosinolates, are potent inducers of mammalian phase 2 detoxification enzymes such as quinone reductase (QR). A greatly simplified bioassay for glucosinolates based on induction and colorimetric detection of QR activity in murine hepatoma cells is described. It is demonstrated that excised leaf disks of Arabidopsis thaliana (ecotype Columbia) can directly and reproducibly substitute for cell-free leaf extracts as inducers of murine QR, which reduces sample preparation to a minimum and maximizes throughput. A comparison of 1 and 3,mm diameter leaf disks indicated that QR inducer potency was proportional to disk circumference (extent of tissue damage) rather than to area. When compared to the QR inducer potency of the corresponding amount of extract, 1,mm leaf disks were equally effective, whereas 3,mm disks were 70% as potent. The QR inducer potency of leaf disks correlated positively with the content of methionine-derived glucosinolates, as shown by the analysis of wild-type plants and mutant lines with lower or higher glucosinolate content. Thus, the microtitre plate-based assay of single leaf disks provides a robust and inexpensive visual method for rapidly screening large numbers of plants in mapping populations or mutant collections and may be applicable to other glucosinolate-producing species. Copyright © 2002 John Wiley & Sons, Ltd. [source]

    Comparisons of breeding systems between two sympatric species, Nastanthus spathulatus (Calyceraceae) and Rhodophiala rhodolirion (Amaryllidaceae), in the high Andes of central Chile

    Abstract Alpine vegetation occurs over a wide range of ecological conditions. Thus, the breeding systems of alpine plants are likely to be diverse and vary from one geographical area to another. The reproductive characteristics of Nastanthus spathulatus (Calyceraceae) and Rhodophiala rhodolirion (Amaryllidaceae), species with contrasting floral morphology, were studied in the high Andes of Chile, which has a Mediterranean-type climate. Natural and supplemental open pollination, and cross pollination and self-pollination trials were carried out in the field. Flower visitors were quantified by field and video observations. Both species had high outcrossing properties, and Nastanthus was strongly self-incompatible. Rhodophiala could form some seed by self-pollination, but fruit and seed sets were much lower after self-pollination compared with outcrossing. The phenology and flower/inflorescence forms of these species supported the view that alpine flowers are comparatively long lived and that the floral display contributes to a large proportion of the plant biomass. Rhodophiala was well attended by a native bee species (Megachile sauleyi) that was appropriately sized for efficient pollination. Although no flower visitors were observed on Nastanthus and wind pollination was discarded experimentally, a high proportion of the flowers produced seeds under natural pollination. Therefore, the seed set was not severely pollen limited in these species. Including previously published information, breeding systems are now known for 12 species on this Mediterranean alpine site and current knowledge suggests an emphasis on outcrossing breeding systems. [source]

    What Determines Australia's Response to Emergencies and Natural Disasters?

    Simon Feeny
    This article examines the determinants of Australia's response to emergencies and natural disasters. It examines the response from the Australian public by examining contributions made to the appeals of the country's largest Non-Governmental Organisation: World Vision of Australia. It also examines the response of the Australian Government. The data include 43 emergencies and natural disasters since 1998. Results suggest that the responses from both the public and government are positively associated with the number of people affected, media coverage, and the level of political and civil freedom in the country where the event occurred. The type and location of the emergency or disaster are important for the public's response. Differences between public and government donations exist: support from the Australian Government is positively associated with smaller countries and there is some evidence that the public donates more to events occurring in larger and poorer countries. [source]

    Natural and human dimensions of environmental change in the proximal reaches of Botswana's Okavango Delta

    Though wetlands are vital for the proper functioning of terrestrial ecosystems and provisioning of a wide range of goods and services, their sustainability is being threatened by inappropriate human resource use practices due to our limited understanding of how these systems operate and lack of appropriately informed interventions. We attempt to address these limitations by using historical CORONA photographs of 1967, Landsat imagery of 1989, 1994 and 2001 and information from the literature to investigate the role of natural and human factors in influencing the direction of environmental change in the proximal reaches of Botswana's Okavango Delta. Results of this investigation point to fragmentation of natural habitats, localised degradation of areas close to perennial water supplies, significant increase in woody cover, significant decrease in open grassland, increase in scrub and shrubs, deterioration in the quality of grazing and depletion of specific woody species. With the direction of change pointing to persistent decrease in the environment's supporting potentials, there is urgent need to adopt intervention strategies potentially capable of enhancing sustainable utilisation of natural resources in this sub-region. [source]

    Sex differences in vocal patterns in the northern muriqui (Brachyteles hypoxanthus)

    Luisa F. Arnedo
    Abstract We investigated whether sex differences in spatial dynamics correlate with rates of staccato and neigh vocalizations in northern muriquis (Brachyteles hypoxanthus) at the Reserva Particular do Patrimônio Natural,Feliciano Miguel Abdala, Minas Gerais, Brazil. A total of 2,727 10,min focal subject samples were collected on 32 adult females and 31 adult males between April 2007 and March 2008. Compared with males, females spent a significantly lower proportion of their time in proximity to other group members and gave staccatos at significantly higher rates while feeding, resting, and traveling. Conversely, males emitted neigh vocalizations at significantly higher rates than females when feeding and resting only. Both sexes gave significantly more staccatos when feeding than when they were engaged in other activities, but their respective rates of neighs did not vary across activities. Both females and males emitted staccato vocalizations at significantly higher rates during times of the year when preferred foods were scarce, but no seasonal differences in the rates of neigh vocalizations were observed in either sex. Females and males showed a reduction in the number of neighbors following staccato vocalizations and an increase in the number of neighbors following neigh vocalizations. Our findings of sex differences in the rates of staccato and neigh vocalizations and the effects of these vocalizations on interindividual spacing are consistent with sex differences in spatial dynamics, and confirm the role of vocal communication in mediating spatial associations in this species. Am. J. Primatol. 72:122,128, 2010. © 2009 Wiley-Liss, Inc. [source]

    Production and perception of sex differences in vocalizations of Wied's black-tufted-ear marmosets (Callithrix kuhlii)

    Adam S. Smith
    Abstract Males and females from many species produce distinct acoustic variations of functionally identical call types. Social behavior may be primed by sex-specific variation in acoustic features of calls. We present a series of acoustic analyses and playback experiments as methods for investigating this subject. Acoustic parameters of phee calls produced by Wied's black-tufted-ear marmosets (Callithrix kuhlii) were analyzed for sex differences. Discriminant function analyses showed that calls contained sufficient acoustic variation to predict the sex of the caller. Several frequency variables differed significantly between the sexes. Natural and synthesized calls were presented to male,female pairs. Calls elicited differential behavioral responses based on the sex of the caller. Marmosets became significantly more vigilant following the playback of male phee calls (both natural and synthetic) than following female phee calls. In a second playback experiment, synthesized calls were modified by independently manipulating three parameters that were known to differ between the sexes (low-, peak-, and end-frequency). When end-frequency-modified calls were presented, responsiveness was differentiable by sex of caller but did not differ from responses to natural calls. This suggests that marmosets did not use end-frequency to determine the sex of the caller. Manipulation of peak-and low-frequency parameters eliminated the discrete behavioral responses to male and female calls. Together, these parameters may be important features that encode for the sex-specific signal. Recognition of sex by acoustic cues seems to be a multivariate process that depends on the congruency of acoustic features. Am. J. Primatol. 71:324,332, 2009. © 2008 Wiley-Liss, Inc. [source]