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31.
BRIAN W BLOUET 《The Geographical journal》2004,170(4):322-329
32.
Anne Kairu Caroline Upton Mark Huxham Kiplagat Kotut Robert Mbeche James Kairo 《社会与自然资源》2018,31(1):74-88
Recent research on participatory forest management (PFM) in the global south has highlighted the existence of a widespread “implementation gap” between the ambitious intent enshrined in legislation and the often partial, disappointing rollout of devolved forest governance on the ground. Here, through an ethnographic case study of forest officers (FOs) in Kenya, we draw on a framework of critical institutionalism to examine how key meso-level actors, or “interface bureaucrats,” negotiate and challenge this implementation gap in everyday forest governance. We go beyond consideration of institutional bricolage in isolation or as an aggregate category, to analyze how bricolage as aggregation, alteration, and/or articulation is variously driven, shaped, and constrained by FOs’ multiple accountabilities and agency. Our analysis highlights the locally specific, contingent, and mutually reinforcing nature of accountability, agency and bricolage, and their explanatory power in relation to the performance and nature of “actually existing” PFM. 相似文献
33.
34.
Marco Vannini Stefano Cannicci Elisha Mrabu Rocco Rorandelli Sara Fratini 《Estuarine, Coastal and Shelf Science》2008,80(4):529-537
Terebralia palustris is a common mud-whelk present at a particularly high density in all Indo-West Pacific mangroves. Young snails feed on nothing but mud while larger specimens are able to feed on fallen leaves too. In Kenya (Mida Creek) under the canopy, competition for mangrove leaves can be very high due to the high density of Sesarmidae crabs. On open exposed muddy platforms, no Sesarmidae occur but the leaf density is very low because the leaves are only randomly present as they are deposited and removed twice a day by the tide. However, the snail density is always very high, raising the question as to whether the snails use a special searching strategy to optimize their resource finding rather than a purely random movement. By analyzing the snails' movements on a uniform area at different levels and comparing them with simulated random paths, we could show that the snails' movements are not purely random. The distribution of different size classes of T. palustris in Mida Creek was known to be quite odd: the same simulation approach suggests that the zonation asymmetry could reasonably be due to the stochastic recruitment of juveniles in space and time and maintained by a substantial long-lasting spatial inertia. 相似文献
35.
ROBIN W. RENAUT R. BERNHART OWEN BRIAN JONES JEAN‐JACQUES TIERCELIN CORINNE TARITS JOHN K. EGO KURT O. KONHAUSER 《Sedimentology》2013,60(2):428-468
Travertine is present at 20% of the ca 60 hot springs that discharge on Loburu delta plain on the western margin of saline, alkaline Lake Bogoria in the Kenya Rift. Much of the travertine, which forms mounds, low terraces and pool‐rim dams, is sub‐fossil (relict) and undergoing erosion, but calcite‐encrusted artefacts show that carbonate is actively precipitating at several springs. Most of the springs discharge alkaline (pH: 8·3 to 8·9), Na‐HCO3 waters containing little Ca (<2 mg l?1) at temperatures of 94 to 97·5°C. These travertines are unusual because most probably precipitated at temperatures of >80°C. The travertines are composed mainly of dendritic and platy calcite, with minor Mg‐silicates, aragonite, fluorite and opaline silica. Calcite precipitation is attributed mainly to rapid CO2 degassing, which led to high‐disequilibrium crystal morphologies. Stratigraphic evidence shows that the travertine formed during several stages separated by intervals of non‐deposition. Radiometric ages imply that the main phase of travertine formation occurred during the late Pleistocene (ca 32 to 35 ka). Periods of precipitation were influenced strongly by fluctuations in lake level, mostly under climate control, and by related changes in the depth of boiling. During relatively arid phases, meteoric recharge of ground water declines, the lake is low and becomes hypersaline, and the reduced hydrostatic pressure lowers the level of boiling in the plumbing system of the hot springs. Any carbonate precipitation then occurs below the land surface. During humid phases, the dilute meteoric recharge increases, enhancing geothermal circulation, but the rising lake waters, which become relatively dilute, flood most spring vents. Much of the aqueous Ca2+ then precipitates as lacustrine stromatolites on shallow firm substrates, including submerged older travertines. Optimal conditions for subaerial travertine precipitation at Loburu occur when the lake is at intermediate levels, and may be favoured during transitions from humid to drier conditions. 相似文献
36.
William Bosworth 《International Journal of Earth Sciences》1994,83(4):671-688
Large areas of north-east Africa were dominated by regional extension in the Late Phanerozoic. Widespread rifting occurred in the Late Jurassic, with regional extension culminating in the Cretaceous and resulting in the greatest areal extent and degree of interconnection of the west, central and north African rift systems. Basin reactivation continued in the Paleocene and Eocene and new rifts probably formed in the Red Sea and western Kenya. In the Oligocene and Early Miocene, rifts in Kenya, Ethiopia and the Red Sea linked and expanded to form the new east African rift system.This complex history of rifting resulted in failed rift basins with low to high strain geometries, a range of associated volcanism and varying degrees of interaction with older structures. One system, the Red Sea rift, has partially attained active seafloor spreading. From a comparison of these basins, a general model of three-dimensional rift evolution is proposed. Asymmetrical crustal geometries dominated the early phases of these basins, accompanied by low angle normal faulting that has been observed at least locally in outcrop. As rifting progressed, the original fault and basin forms were modified to produce larger, more through-going structures. Some basins were abandoned, others experienced reversals in regional dip and, in general, extension and subsidence became focused along narrower zones near the rift axes. The final transition to oceanic spreading was accomplished in the Red Sea by a change to high angle, planar normal faulting and diffuse dike injection, followed by the organization of an axial magma chamber. 相似文献
37.
The Magadi area, located in the southern part of the Kenya Rift, is a seismically active region where rifting is still in progress. The recent tectonic activity has been investigated through a seismological survey and the study of neotectonic joints found in Lake Magadi sediments, which were deposited some 5000 years ago. The structural analysis of these open fractures was combined with a quantitative analysis of the orientation and size characteristics of imagery faults. The gathered data demonstrate (1) that the majority of the systematic joints have straight and parallel trajectories with a common en echelon mode of propagation displayed through a rich variety of patterns, and (2) that there is a self-similarity in fault and joint principal directions recognised at the different telescopic scales. SPOT image (1:125,000), aerial photos (1:76,000), and outcrop fieldwork reveal two important structural orientations which are N015°E and N015°W. The N015°E regional direction is consistent with the orientation of the southern segment of the Kenya Rift. Structural analysis is supported by results of a joint microseismic investigation in the Lake Magadi area. Obtained focal mechanism solutions indicate an E–W to ESE–WNW normal faulting extension direction. 相似文献
38.
Catherine S. Dolan 《Geoforum》2010,41(1):33-43
Fairtrade was founded to alleviate poverty and economic injustice through a market-based form of solidarity exchange. Yet with the increasing participation of transnational food corporations in Fairtrade sourcing, new questions are emerging on the extent to which the model offers an alternative to the inimical tendencies of neoliberalism. Drawing on a qualitative research project of Kenyan Fairtrade tea, this paper examines how the process of corporate mainstreaming influences the structure and outcomes of Fairtrade, and specifically the challenges it poses for the realization of Fairtrade’s development aspirations. It argues firstly that whilst tea producers have experienced tangible benefits from Fairtrade’s social premium, these development ‘gifts’ have been conferred through processes marked less by collaboration and consent than by patronage and exclusion. These contradictions are often glossed by the symbolic force of Fairtrade’s key tenets - empowerment, participation, and justice - which simultaneously serve to neutralize critique and mystify the functions that Fairtrade performs for the political economy of development and neoliberalism. Second, building on recent critiques of corporate social responsibility, the paper explores how certain neoliberal rationalities are emboldened through Fairtrade, as a process of mainstreaming installs new metrics of governance (standards, certification, participation) that are at once moral and technocratic, voluntary and coercive, and inclusionary and marginalizing. The paper concludes that these technologies have divested exchange of mutuality, as the totemic features of neoliberal regulation - standards, procedures and protocols - increasingly render north south partnerships ever more virtual and depoliticized. 相似文献
39.
Kefa M. Otiso 《Singapore journal of tropical geography》2002,23(3):252-267
Forced evictions are widespread in Kenyan cities and are, on the surface, caused by conflicts in land rights, non–payment of excessive land and house rents, and urban redevelopment. But, more fundamentally, evictions are due to factors embedded in the country's political economy, in particular, the grossly inequitable land ownership structure which makes it difficult for the poor to access land and decent shelter. Evictions cause significant socioeconomic hardship to individuals, affecting cities and whole nations. To avoid evictions, I argue that Kenya must make its political economy more inclusive, implement land reform, domesticate its municipal planning and related by–laws, and create a proactive slum settlements policy. This paper is based on secondary data, largely drawn from the extensive coverage of urban evictions in recent decades in Kenya's leading newspapers. 相似文献
40.
ROGERS NICK W.; EVANS PETER J.; BLAKE STEVE; SCOTT STUART C.; HAWKESWORTH CHRIS J. 《Journal of Petrology》2004,45(9):1747-1776
A suite of peralkaline trachytes from Longonot volcano, Kenya,which erupted during the last 6000 years, has been analysedfor major and trace elements, Pb and Nd isotopes, and UThRadisequilibria. The lavas are divided into three stratigraphicgroups of trachytes (Lt2a, Lt2b and Lt3), and hybrid lavas,designated LMx1 and LMx2, which, respectively, pre-date andpost-date the Lt2 lavas. Major and trace elements are consistent,with up to 37% within-group fractional crystallization of predominantlyalkali feldspar. The parental magma for the different trachytegroups had a more mafic compositionprobably hawaiitic.Nd and Pb isotopes show minimal variation, both within and betweenmagma groups, and indicate that up to 10% comendite magma fromthe neighbouring Olkaria volcanic field may have intermixedwith the Longonot magma. (230Th/238U) disequilibria indicatethat limited U/Th fractionation occurred during the past 10kyr, whereas (226Ra/230Th) disequilibria reflect the effectof alkali feldspar fractionation >8 kyr ago in the Lt2a lavas,between 3 and 7 kyr ago in the Lt2b lavas and in the past 3kyr for the Lt3 lavas. (226Ra/230Th) disequilibria in the Lt2blavas are interpreted using a model that combines the equationsof radioactive decay and in-growth with Rayleigh crystallizationto give fractionation rates of about 0·2 x 104/yearfor the evolution of hawaiite to trachyte, but more rapid ratesof up to 3 x 104/year for fractionation within the trachytesequence. (226Ra/230Th) from two whole-rockalkali feldsparpairs are interpreted to show the crystals formed at 5800 yearsBP (Lt2b) and 2800 years BP (Lt3), implying that phenocrystformation continued almost up to the time of eruption. The resultsstrongly indicate that fractionated magmas can be stored forperiods on the order of 10002500 years prior to eruption,whereas other magmas were erupted as fractionation was proceeding. KEY WORDS: trachyte; magma chambers; u-series; Kenya 相似文献