607 research outputs found
An examination of spatial variability in the timing and magnitude of Holocene relative sea-level changes in the New Zealand archipelago
Holocene relative sea-level (RSL) changes have been reconstructed for four regions within the New Zealand archipelago: the northern North Island (including Northland, Auckland, and the Coromandel Peninsula); the southwest coast of the North Island; the Canterbury coast (South Island); and the Otago coast (South Island). In the North Island the RSL highstand commenced c. 8100â7240 cal yr BP when present mean sea-level (PMSL) was first attained. This is c. 600â1400 years earlier than has been previously indicated for the New Zealand region as a whole, and is consistent with recent Holocene RSL reconstructions from Australia. In North Island locations the early-Holocene sea-level highstand was quite pronounced, with RSL up to 2.75 m higher than present. In the South Island the onset of highstand conditions was later, with the first attainment of PMSL being between 7000â6400 cal yr BP. In the mid-Holocene the northern North Island experienced the largest sea-level highstand, with RSL up to 3.00 m higher than present. This is demonstrably higher than the highstand recorded for the southwest North Island and Otago regions. A number of different drivers operating at a range of scales may be responsible for the spatial and temporal variation in the timing and magnitude of RSL changes within the New Zealand archipelago. One possible mechanism is the north-south gradient in RSL that would arise in the intermediate field around Antarctica in response to the reduced gravitational attraction of the Antarctic Ice Sheet (AIS) as it lost mass during the Holocene. This gradient would be enhanced by the predicted deformation of the lithosphere in the intermediate field of the Southern Ocean around Antarctica due to hydro-isostatic loading and mass loss of the AIS. However, no such long-wavelength signals in sea-surface height or solid Earth deformation are evident in glacial isostatic adjustment (GIA) model predictions for the New Zealand region, while research from Australia has suggested that north-south variations in Holocene RSL changes due to hydro-isostatic influences are limited or non-existent. At the regional-to local-scale, post-glacial meltwater loading on the continental shelf around New Zealand is predicted by GIA modelling to have a significant effect on the timing and magnitude of RSL changes through the phenomenon of continental levering. The spatial variation in continental levering is controlled by the configuration of the coast and the width of the adjacent continental shelf, with continental levering providing a robust explanation for the observed spatial and temporal variations in RSL changes. Further research is required to characterise the regional and local effects of different tectonic regimes, wave climates, and sediment regimes. These are potentially very significant drivers of RSL variability at the regional-to local-scale. However, the magnitude of their potential effects remains equivocal
The management of tree genetic resources and the livelihoods of rural communities in the tropics: non-timber forest products, smallholder agroforestry practices and tree commodity crops
Products and services provided by trees in forests and farmland support the needs and promote the wellbeing of hundreds of millions of people in the tropics. Value depends on managing both the diversity of tree species present in landscapes and the genetic variation within these species. The benefits from trees and their genetic resources are, however, often not well quantified because trade is frequently outside formal markets, there is a multiplicity of species and ways in which trees are used and managed, and genetic diversity within species is frequently not given proper consideration. We review here what is known about the value of trees to rural communities through considering three production categories: non-timber products harvested from trees in natural and managed forests and woodlands; the various products and services obtained from a wide range of trees planted and/or retained in smallholdersâ agroforestry systems; and the commercial products harvested from cultivated tree commodity crops. Where possible, we focus on the role of intra-specific genetic variation in providing support to livelihoods, and for each of the three production categories we also consider wider conservation and sustainability issues, including the linkages between categories in terms of management. Challenges to âconventional wisdomâ on tree resource use, value and management â such as in the posited links between commercialisation, cultivation and conservation â are highlighted, and constraints and opportunities to maintain and enhance value are described
Peach palm, Bactris gasipaes Kunth
Yielding fruits and palm hearts, peach palm (Bactris gasipaes) was a staple food crop for many pre-Columbian Amerindian communities in the lowland humid neotropics. The gene pool of cultivated peach palm and its wild relatives is rich in diversity but is subject to genetic erosion creating an urgent need to sample and conserve germplasm. This booklet provides an overview of existing knowledge of the genus with emphasis on genetic resources. Chapters cover the following topics: taxonomy and distribution, botanical description, uses and properties, origin and domestication, genetic diversity, collecting and evaluation, breeding, propagation, agronomy, production areas, commercial potential, limitations and future prospects. An appendix presents details of institutions and scientists managing gene banks and conduction research on peach palm. (Abstract © CAB ABSTRACTS, CAB International
Variabilidade genĂ©tica e fluxo gĂȘnico em populaçÔes hĂbridas e silvestres de pupunha acessada com marcadores RAPD
As populaçÔes hĂbridas de pupunha (Bactris gasipaes Kunth) acumularam variabilidade genĂ©tica provenientes de raças primitivas ao seu redor, o que deveria aumentar sua variabilidade. Para testar esta hipĂłtese, avaliou-se a variabilidade genĂ©tica de populaçÔes hĂbridas por meio de marcadores RAPD utilizando 176 plantas mantidas no Banco Ativo de Germoplasma do INPA, Manaus-AM, sendo quatro populaçÔes hĂbridas [BelĂ©m (n=26); Manaus (n=38); Iquitos, Peru (n=41); YurimĂĄguas, Peru (n=41)], duas populaçÔes silvestres (B. gasipaes variedade chichagui) tipos 1 (n=21) e 3 (n=7), e duas amostras de espĂ©cie afim, B. riparia, e compararam-se os parĂąmetros genĂ©ticos com estudos das raças primitivas. Oito iniciadores RAPD geraram 88 marcadores polimĂłrficos e 11 monomĂłrficos. O teste de replicabilidade apresentou uma similaridade de Dice 0,67, considerado aceitĂĄvel. A heterozigosidade mĂ©dia das populaçÔes hĂbridas foi 0,34 e o polimorfismo foi 87,9%, maiores que nas silvestres (0,31; 74,7%). O dendrograma das similaridades de Dice nĂŁo apresentou grupos que representassem claramente as populaçÔes hĂbridas. O fluxo gĂȘnico entre Iquitos e YurimĂĄguas (Nm=12,75) e entre Iquitos e Manaus (Nm=9,47) foi alto, enquanto o fluxo entre BelĂ©m e Manaus (Nm=7,72) foi menor que o esperado, possivelmente devido Ă influĂȘncia da raça SolimĂ”es. O alto valor de heterozigosidade em Manaus (0,31) parece ser resultado da uniĂŁo de duas dispersĂ”es apĂłs a domesticação: a do oeste amazĂŽnico, com Iquitos e YurimĂĄguas, e a do leste amazĂŽnico, com BelĂ©m, que se juntam em Manaus. No entanto, essas populaçÔes nĂŁo apresentaram acĂșmulo de variabilidade genĂ©tica tĂŁo expressiva para diferenciĂĄ-las das raças primitivas
Adsorption of Reactive Particles on a Random Catalytic Chain: An Exact Solution
We study equilibrium properties of a catalytically-activated annihilation reaction taking place on a one-dimensional chain of length () in which some segments (placed at random, with mean concentration
) possess special, catalytic properties. Annihilation reaction takes place,
as soon as any two particles land onto two vacant sites at the extremities
of the catalytic segment, or when any particle lands onto a vacant site on
a catalytic segment while the site at the other extremity of this segment is
already occupied by another particle. Non-catalytic segments are inert with
respect to reaction and here two adsorbed particles harmlessly coexist. For
both "annealed" and "quenched" disorder in placement of the catalytic segments,
we calculate exactly the disorder-average pressure per site. Explicit
asymptotic formulae for the particle mean density and the compressibility are
also presented.Comment: AMSTeX, 27 pages + 4 figure
'To live and die [for] Dixie': Irish civilians and the Confederate States of America
Around 20,000 Irishmen served in the Confederate army in the Civil War. As a result, they left behind, in various Southern towns and cities, large numbers of friends, family, and community leaders. As with native-born Confederates, Irish civilian support was crucial to Irish participation in the Confederate military effort. Also, Irish civilians served in various supporting roles: in factories and hospitals, on railroads and diplomatic missions, and as boosters for the cause. They also, however, suffered in bombardments, sieges, and the blockade. Usually poorer than their native neighbours, they could not afford to become 'refugees' and move away from the centres of conflict. This essay, based on research from manuscript collections, contemporary newspapers, British Consular records, and Federal military records, will examine the role of Irish civilians in the Confederacy, and assess the role this activity had on their integration into Southern communities. It will also look at Irish civilians in the defeat of the Confederacy, particularly when they came under Union occupation. Initial research shows that Irish civilians were not as upset as other whites in the South about Union victory. They welcomed a return to normalcy, and often 'collaborated' with Union authorities. Also, Irish desertion rates in the Confederate army were particularly high, and I will attempt to gauge whether Irish civilians played a role in this. All of the research in this paper will thus be put in the context of the Drew Gilpin Faust/Gary Gallagher debate on the influence of the Confederate homefront on military performance. By studying the Irish civilian experience one can assess how strong the Confederate national experiment was. Was it a nation without a nationalism
Estudo da viabilidade econÎmica da irrigação da pupunheira (Bactris Gasipaes H.B.K.) para Ilha Solteira - SP, Brasil
Adubação orgùnica e mineral para a produção de palmito da pupunheira na AmazÎnia Central
Guidelines for irrigation scheduling of peach palm for heart-of-palm production in the SĂŁo Francisco Valley, Brazil
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