993 resultados para 1781


Relevância:

10.00% 10.00%

Publicador:

Resumo:

As a result of rapid urbanisation, population growth, changes in lifestyle, pollution and the impacts of climate change, water provision has become a critical challenge for planners and policy-makers. In the wake of increasingly difficult water provision and drought, the notion that freshwater is a finite and vulnerable resource is increasingly being realised. Many city administrations around the world are struggling to provide water security for their residents to maintain lifestyle and economic growth. This chapter reviews the global challenge of providing freshwater to sustain lifestyles and economic growth, and the contributing challenges of climate change, urbanisation, population growth and problems in rainfall distribution. The chapter proceeds to evaluate major alternatives to current water sources such as conservation, recycling and reclamation, and desalination. Integrated water resource management is briefly looked at to explore its role in complementing water provision. A comparative study on alternative resources is undertaken to evaluate their strengths, weaknesses, opportunities and constraints, and the results are discussed.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Electrospray ionisation tandem mass spectrometry has allowed the unambiguous identification and quantification of individual lens phospholipids in human and six animal models. Using this approach ca. 100 unique phospholipids have been characterised. Parallel analysis of the same lens extracts by a novel direct-insertion electron-ionization technique found the cholesterol content of human lenses to be significantly higher (ca. 6 times) than lenses from the other animals. The most abundant phospholipids in all the lenses examined were choline-containing phospholipids. In rat, mouse, sheep, cow, pig and chicken, these were present largely as phosphatidylcholines, in contrast 66% of the total phospholipid in Homo sapiens was sphingomyelin, with the most abundant being dihydrosphingomyelins, in particular SM(d18:0/16:0) and SM(d18:0/24:1). The abundant glycerophospholipids within human lenses were found to be predominantly phosphatidylethanolamines and phosphatidylserines with surprisingly high concentrations of ether-linked alkyl chains identified in both classes. This study is the first to identify the phospholipid class (head-group) and assign the constituent fatty acid(s) for each lipid molecule and to quantify individual lens phospholipids using internal standards. These data clearly indicate marked differences in the membrane lipid composition of the human lens compared to commonly used animal models and thus predict a significant variation in the membrane properties of human lens fibre cells compared to those of other animals. © 2008 Elsevier B.V. All rights reserved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

It is becoming increasingly popular to consider species interactions when managing ecological foodwebs. Such an approach is useful in determining how management can affect multiple species, with either beneficial or detrimental consequences. Identifying such actions is particularly valuable in the context of conservation decision making as funding is severely limited. This paper outlines a new approach that simplifies the resource allocation problem in a two species system for a range of species interactions: independent, mutualism, predator-prey, and competitive exclusion. We assume that both species are endangered and we do not account for decisions over time. We find that optimal funding allocation is to the conservation of the species with the highest marginal gain in expected probability of survival and that, across all except mutualist interaction types, optimal conservation funding allocation differs between species. Loss in efficiency from ignoring species interactions was most severe in predator-prey systems. The funding problem we address, where an ecosystem includes multiple threatened species, will only become more commonplace as increasing numbers of species worldwide become threatened. © 2011 Elsevier B.V.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Methacrylate-based hydrogels, such as homo- and copolymers of 2-hydroxyethyl methacrylate (HEMA), have demonstrated significant potential for use in biomedical applications. However, many of these hydrogels tend to resist cell attachment and growth at their surfaces, which can be detrimental for certain applications. In this article, glycidyl methacrylate (GMA) was copolymerized with HEMA to generate gels functionalized with epoxide groups. The epoxides were then functionalized by two sequential click reactions, namely, nucleophilic ring opening of epoxides with sodium azide and then coupling of small molecules and peptides via Huisgen's copper catalyzed 1,3-dipolar cycloaddition of azides with alkynes. Using this strategy it was possible to control the degree of functionalization by controlling the feed ratio of monomers during polymerization. In vitro cell culture of human retinal pigment epithelial cell line (ARPE-19) with the hydrogels showed improved cell adhesion, growth and proliferation for hydrogels that were functionalized with a peptide containing the RGD sequence. In addition, the cell attachment progressively decreased with increasing densities of the RGD containing peptide. In summary, a facile methodology has been presented that gives rise to hydrogels with controlled degrees of functionality, such that the cell response is directly related to the levels and nature of that functionality.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The collection contains correspondence among members of the Ehrenberg and Rosenzweig families, including letters from Franz Rosenzweig, Adam Rosenzweig and Richard Ehrenberg, as well as with other parties, including Leopold Zunz, Adelheid Zunz, Claire von Gluemer, and Heinrich Heine (copies only). Also included are engagement contracts, marriage banns, school curricula and certificates, character references, eulogies, family histories, and other documents concerning family members. This material also reflects much of the history of the Samsonschule in Wolfenbuettel of which members of the Ehrenberg family were principals.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The collection contains items relating to individual members of the family as well as the Seixas family in general. Included are papers of the following persons: Isaac Mendes Seixas (1708/9-1780/1), a copy of A voyage to Hudson's--Bay, by Henry Ellis, inscribed with his name on the title page, along with additional inscriptions on the end papers (1748); and a daily prayer book printed in Amsterdam (title page missing), with an inscription on the first page indicating that the book was owned by Seixas in 1758/9, and subsequently by his grandson, Theodore J. Seixas, in 1816/17.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Digital image

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Ystävä sä lapsien. Collections of Finnish language children s hymns and spiritual songs from 1824─1938 and their influence on the Hymnal 1938. The Hymnal has been the common song book of Lutheran parishes since the 1500s. In the beginning, the congregations sang the hymns from memory led by the choir or the church musician. The fundamentals of Christian faith are taught through the hymns, both in church and in family devotions. The Hymnal was the only song book of the church in Finland until the end of the 1800s. This study attempts to clarify when and by who were spiritual songs and hymns for children written in Finland. Research materials used were all the books I could find (approximately 200), whose headings were for pupils and young children in the home and school circles. The method of study is historical and analytical. In the first chapter, it is explained that children s literature in Finland differentiated from other literature at the end of the 1700s. Eric Juvelius published a small prayer book in 1781 with the prayer Gud, som hafver barnen kär / Jumala joka Lapsia rakasta. From that, after many Finnish translations, the first verse of the hymn Ystävä sä lapsien took shape. The second chapter considers singing instruction in the folk school from the beginning of the 1860s. Textbooks, including songbooks, were produced for the pupils. Some of the first pioneers in producing these materials were the teachers P.J. Hannikainen, Sofie Lithenius, Mikael Nyberg, Anton Rikström and Aksel Törnudd, as well as Hilja Haahti, Immi Hellén and Alli Nissinen, who were all teachers gifted in writing poetry. Several new spiritual songs appeared in the folk school songbooks. Hymns were sung often, especially in connection with church year celebrations. Children s songs in Christian education are discussed in the third chapter. The Lutheran Evangelical Association of Finland recognized children already in its early song collections. The illustrative teaching methods in the folk school influenced the Sunday school activities and especially the Sunday school hymns. Hymns introduced as exclusively for children and pupils which appear in the Hymnal from 1886 and the supplement to the 1923 Hymnal are explored in the fourth and fifth chapters. The study shows that the renewal of church life at the beginning of the 1900s also resulted in an increase of the number of spiritual songs for children. This is also seen in the diverse choice of songs in the supplementary materials from 1923. The final chapter deals with the School and Childhood section of the 1938 Hymnal. The Hymnal committee did not think that the already well known folk school and Sunday school songs received enough attention in the Hymnal. Those songs were, among others, Kautta tyynen, vienon yön, Oi, katsopa lintua oksalla puun, Olen Luojani pikku varpunen, Rakas Isä taivahan ja Tuolla keinuu pieni pursi. Heikki Klemetti, Ilmari Krohn, Armas Maasalo and Aarni Voipio influenced the opinion that the spiritual songs still were not suitable to be sung in church. Hymns for children and pupils were brought into the same line as the entire Hymnal. The same hymn tunes, which were mainly old ones, were used as common settings for numerous hymn texts. No special type of melody emerged for the children s hymns. It was still notable that hymns for children and pupils were collected at all. In addition, the Hymnal committee marked those verses suggested for singing in both the folk school and Sunday school with an asterisk (*) throughout the entire Hymnal.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Dry sliding wear behavior of die-cast ADC12 aluminum alloy composites reinforced with short alumina fibers were investigated by using a pin-on-disk wear tester. The Al2O3 fibers were 4 mu m in diameter and were present in volume fractions (T-f)ranging from 0.03 to 0.26, The length of the fiber varied from 40 to 200 mu m. Disks of aluminum-alumina composites were rubbed against a pin of nitrided stainless steel SUS440B with a load of 10 N at a sliding velocity of 0.1 m/s. The unreinforced ADC 12 aluminum alloy and their composites containing low volume fractions of alumina (V-f approximate to 0.05) showed a sliding-distance-dependent transition from severe to mild wear. However, composites containing high volume fractions of alumina ( V-f > 0.05) exhibited only mild wear for all sliding distances. The duration of occurrence of the severe wear regime and the wear rate both decrease with increasing volume fraction. In MMCs the wear rate in the mild wear regime decreases with increase in volume fraction: reaching a minimum value at V-f = 0.09 Beyond V-f = 0.09 the wear rate increasesmarginally. On the other hand, the wear rate of the counterface (steel pin) was found to increase moderately with increase in V-f. From the analysis of wear data and detailed examination of (a) worn surfaces, (b) their cross-sections and (c) wear debris, two modes of wear mechanisms have been identified to be operative, in these materials and these are: (i) adhesive wear in the case of unreinforced matrix material and in MMCs with low Vf and (ii) abrasive wear in the case of MMCs with high V-f. (C) 2000 Elsevier Science Ltd. All rights reserved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Modern sample surveys started to spread after statistician at the U.S. Bureau of the Census in the 1940s had developed a sampling design for the Current Population Survey (CPS). A significant factor was also that digital computers became available for statisticians. In the beginning of 1950s, the theory was documented in textbooks on survey sampling. This thesis is about the development of the statistical inference for sample surveys. For the first time the idea of statistical inference was enunciated by a French scientist, P. S. Laplace. In 1781, he published a plan for a partial investigation in which he determined the sample size needed to reach the desired accuracy in estimation. The plan was based on Laplace s Principle of Inverse Probability and on his derivation of the Central Limit Theorem. They were published in a memoir in 1774 which is one of the origins of statistical inference. Laplace s inference model was based on Bernoulli trials and binominal probabilities. He assumed that populations were changing constantly. It was depicted by assuming a priori distributions for parameters. Laplace s inference model dominated statistical thinking for a century. Sample selection in Laplace s investigations was purposive. In 1894 in the International Statistical Institute meeting, Norwegian Anders Kiaer presented the idea of the Representative Method to draw samples. Its idea was that the sample would be a miniature of the population. It is still prevailing. The virtues of random sampling were known but practical problems of sample selection and data collection hindered its use. Arhtur Bowley realized the potentials of Kiaer s method and in the beginning of the 20th century carried out several surveys in the UK. He also developed the theory of statistical inference for finite populations. It was based on Laplace s inference model. R. A. Fisher contributions in the 1920 s constitute a watershed in the statistical science He revolutionized the theory of statistics. In addition, he introduced a new statistical inference model which is still the prevailing paradigm. The essential idea is to draw repeatedly samples from the same population and the assumption that population parameters are constants. Fisher s theory did not include a priori probabilities. Jerzy Neyman adopted Fisher s inference model and applied it to finite populations with the difference that Neyman s inference model does not include any assumptions of the distributions of the study variables. Applying Fisher s fiducial argument he developed the theory for confidence intervals. Neyman s last contribution to survey sampling presented a theory for double sampling. This gave the central idea for statisticians at the U.S. Census Bureau to develop the complex survey design for the CPS. Important criterion was to have a method in which the costs of data collection were acceptable, and which provided approximately equal interviewer workloads, besides sufficient accuracy in estimation.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

In this study, we investigated nonlinear measures of chaos of QT interval time series in 28 normal control subjects, 36 patients with panic disorder and 18 patients with major depression in supine and standing postures. We obtained the minimum embedding dimension (MED) and the largest Lyapunov exponent (LLE) of instantaneous heart rate (HR) and QT interval series. MED quantifies the system's complexity and LLE predictability. There was a significantly lower MED and a significantly increased LLE of QT interval time series in patients. Most importantly, nonlinear indices of QT/HR time series, MEDqthr (MED of QT/HR) and LLEqthr (LLE of QT/HR), were highly significantly different between controls and both patient groups in either posture. Results remained the same even after adjusting for age. The increased LLE of QT interval time, series in patients with anxiety and depression is in line with our previous findings of higher QTvi (QT variability index, a log ratio of QT variability corrected for mean QT squared divided by heart rate variability corrected for mean heart rate squared) in these patients, using linear techniques. Increased LLEqthr (LLE of QT/HR) may be a more sensitive tool to study cardiac repolarization and a valuable addition to the time domain measures such as QTvi. This is especially important in light of the finding that LLEqthr correlated poorly and nonsignificantly with QTvi. These findings suggest an increase in relative cardiac sympathetic activity and a decrease in certain aspects of cardiac vagal function in patients with anxiety as well as depression. The lack of correlation between QTvi and LLEqthr suggests that this nonlinear index is a valuable addition to the linear measures. These findings may also help to explain the higher incidence of cardiovascular mortality in patients with anxiety and depressive disorders. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The information-theoretic approach to security entails harnessing the correlated randomness available in nature to establish security. It uses tools from information theory and coding and yields provable security, even against an adversary with unbounded computational power. However, the feasibility of this approach in practice depends on the development of efficiently implementable schemes. In this paper, we review a special class of practical schemes for information-theoretic security that are based on 2-universal hash families. Specific cases of secret key agreement and wiretap coding are considered, and general themes are identified. The scheme presented for wiretap coding is modular and can be implemented easily by including an extra preprocessing layer over the existing transmission codes.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

结合近年来发表的对金属材料采用球形压头的微压痕实验结果及Johnson对应原理,讨论了在传统弹塑性理论下锥形压头在计及压头顶端曲率半径影响时硬度的解答形式。进而得出结论:压头尖端曲率半径不是引起尺度效应的根源,相反,它全使尺度效应减弱。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

El presente trabajo se realizó en Geneticos Nicaraguenses (REGEN) adscrito Nacional Agraria a finales de 1995 con el la Prueba de Envejecimiento Acelerado (PEA) el Programa a la Universidad propósito de utilizar de semillas como una herramienta más para evaluar vigor, atributo relacionado con la emergencia en campo y la almacenabilidad de las mismas. El estudio se realizó con seis variedades (dos mejoradas modernas y cuatro locales o tradicionales) sometidas a condiciones de envejecimiento acelerado a fin de diferenciar los genotipos en base a su comportamiento después de la prueba mencionada. Se evaluaron en laboratorio y en campo en un diseño completamente al azar, las variables siguientes: Germinación estándar. número de plantas emergidas. velocidad de emergencia, materia seca de plántulas y de raíces. Del análisis de los resultados se llego a las conclusiones siguientes: 1) De manera general. la PA permitió hacer una diferenciación entre los materiales estudiados: las variedades locales mostraron un comportamiento superior con relación a las mejoradas. 2) La variedad local "Chile" se vio menos afectada por la PEA considerándose como un material muy vigoroso y con alto potencial de almacenamiento. ) La reducción de la terminación inicial de las variedades locales después de la PEA fue hasta un 24%. en cambio para las mejoradas fue mayor de un 48%. 4)Las variables materia seca de plántula y de raíz no permitieron valorar objetivamente la calidad de las semillas debido a las variaciones observadas. 5) Al correlacionar los resultados de la Prueba de Germinación Estándar y de la PEA con la emergencia en campo, la primera mostró un mayor coeficiente de correlación (0.98 **)con relación a la segunda prueba (0.82*). 6) A fin de mejorar la metodología de la PEA se recomienda, para llegar a conclusiones más definitivas, uniformizar ciertos parámetros de las semillas de los materiales genéticos sujetos a estudio como son: Calidad fisiológica Inicial, contenido de humedad Inicial, condiciones previas de almacenamiento, color de testa, rugosidad etc.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Aborda aspectos relacionados à pressão exercida pelos parlamentares federais para a inclusão de novas dotações na lei orçamentária anual (LOA), sem que seja realizada uma análise das políticas públicas propostas, de forma a priorizar aquelas que julgarem mais relevantes.