نتایج جستجو برای: stadial transmission
تعداد نتایج: 246081 فیلتر نتایج به سال:
A major puzzle of paleoclimatology is why, after a long interval of cooling climate, each late Quaternary ice age ended with a relatively short warming leg called a termination. We here offer a comprehensive hypothesis of how Earth emerged from the last global ice age. A prerequisite was the growth of very large Northern Hemisphere ice sheets, whose subsequent collapse created stadial condition...
The position of the Intertropical Convergence Zone (ITCZ) is sensitive to changes in the balance of heat between the hemispheres which has fundamental implications for tropical hydrology and atmospheric circulation. Although the ITCZ is thought to experience the largest shifts in position during deglacial stadial events, the magnitude of shifts has proven difficult to reconstruct, in part becau...
[1] We present a new hypothesis to explain the millennial-scale temperature variability recorded in ice cores known as Dansgaard-Oeschger (DO) cycles. We propose that an ice shelf acted in concert with sea ice to set the slow and fast timescales of the DO cycle, respectively. The abrupt warming at the onset of a cycle is caused by the rapid retreat of sea ice after the collapse of an ice shelf....
BACKGROUND & OBJECTIVES Culex quinquefasciatus is one of the principal vectors of West Nile virus (WNV). The mosquito also acts as a bridge vector as it feeds on both birds and humans. In the background of the recent reports of WNV activity in Kerala and Assam with fatalities, a study was initiated to determine the growth kinetics and transmission mechanisms of three strains of WNV in two popul...
To describe the midgut microbial diversity and to find the candidate bacteria for the genetic manipulation for the generation of paratransgenic Anopheline mosquitoes refractory to transmission of malaria, the microbiota of wild larvae and adult Anopheles stephensi mosquito midgut from southern Iran was studied using a conventional cell-free culture technique and analysis of a 16S ribosomal RNA ...
The causes of Late Pleistocene megafaunal extinctions (60,000 to 11,650 years ago, hereafter 60 to 11.65 ka) remain contentious, with major phases coinciding with both human arrival and climate change around the world. The Americas provide a unique opportunity to disentangle these factors as human colonization took place over a narrow time frame (~15 to 14.6 ka) but during contrasting temperatu...
The chronology of deglacial meltwater pulses from the Laurentide Ice Sheet is well documented. However, the deglacial history of the North American-Arctic (north-eastern Laurentide and Innuitian) and western Greenland ice sheets draining into the Labrador Sea via Baffin Bay is less well constrained. Here we present new high-resolution, radiocarbon-dated records from the central Baffin Bay spann...
Deepwater circulation significantly changed during the last deglaciation from a shallow to deep-reaching overturning cell. This change went along with drawdown of isotopically light waters into abyss and deep ocean warming that stratification salinity-to temperature-controlled mode. Yet, exact mechanisms causing these changes are still unknown. Furthermore, long-standing idea complete shutdown ...
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