The effect of reionization on the COBE normalization     

Louise M. Griffiths  Andrew R. Liddle 《Monthly notices of the Royal Astronomical Society》2001,324(3):769-771

We point out that the effect of reionization on the microwave anisotropy power spectrum is not necessarily negligible on the scales probed by COBE . It can lead to an upward shift of the COBE normalization by more than the 1 σ error quoted, ignoring reionization. We provide a fitting function to incorporate reionization into the normalization of the matter power spectrum.  相似文献   

The Characteristics of Solar X-Class Flares and CMEs: A Paradigm for Stellar Superflares and Eruptions?     

Louise K. Harra  Carolus J. Schrijver  Miho Janvier  Shin Toriumi  Hugh Hudson  Sarah Matthews  Magnus M. Woods  Hirohisa Hara  Manuel Guedel  Adam Kowalski  Rachel Osten  Kanya Kusano  Theresa Lueftinger 《Solar physics》2016,291(6):1761-1782

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Vertical Hydraulic Gradient Estimation in Clay Till,Using MiHPT Advanced Direct-Push Technology     

Louise Rosenberg  Mette M. Broholm  Nina Tuxen  Ida Henriette Kerrn-Jespersen  Gro Lilbæk  Poul L. Bjerg 《Ground Water Monitoring & Remediation》2022,42(1):29-37

The vertical transport of contaminants from source areas is employed in many risk assessment models and screening tools in order to estimate the contaminant mass discharge (CMD) into underlying aquifers. The key parameters for estimating CMD are the contaminant source area and concentration, and the vertical water flux, the latter of which depends on the vertical hydraulic conductivity and the vertical hydraulic gradient in the subsurface. This study focuses on advancing the use of the combined membrane interface probe hydraulic profiling tool (MiHPT) to investigate the vertical hydraulic gradient across a clay till overlying a sandy aquifer at a contaminated site in Denmark. Only the HPT is necessary for the estimate of vertical hydraulic gradient. The hydraulic head, clay till thickness, and resulting vertical hydraulic gradients found using the MiHPT compared well with observations from nearby nested wells. The parameter with the largest discrepancy was the thickness of the clay till. The advantage of the MiHPT is its relatively quick depth discrete access to information regarding subsurface permeability, vertical hydraulic gradients and contaminant distribution across a site. In this case study, performance of additional dissipationtests during the HPT log to acquire determination of the vertical hydraulic gradient increased the cost by 3% compared to standard HPT logs.  相似文献   

Timing and maximum flood level of the Early Holocene glacial lake Nedre Glomsjø outburst flood,Norway     

Fredrik Høgaas  Louise Hansen  Ivar Berthling  Martin Klug  Oddvar Longva  Helle Daling Nannestad  Lars Olsen  Anders Romundset 《Boreas: An International Journal of Quaternary Research》2023,52(3):295-313

This study discusses the timing and maximum flood level of the Nedre Glomsjø outburst flood, Norway, based on sediment records retrieved from 15 bog and lake basins located close to the purported maximum flooded level. The sediment records in 12 of the basins consist of a distinct light-coloured silty bed that is correlated to the outburst-flood-deposited ‘Romerike Silt Bed’ identified elsewhere in the region. The silt bed is recorded in basins up to a certain elevation and is absent above this level. The new maximum flood level inferred from the basin sediment records exceeds the established landform-induced palaeostage indicators by 5–10 m. The data indicate a higher maximum flood level and larger inundation area than previously suggested and highlight the importance of acquiring a wide range of geological data when reconstructing palaeofloods. Radiocarbon dates of terrestrial macrofossils found stratigraphically above and below the Romerike Silt Bed suggest that the glacial lake Nedre Glomsjø outburst flood occurred between 10.5 and 10.3 cal. ka BP. The new and well-constrained timing of the outburst flood is beneficial for reconstructing regional deglaciation and provides a precise age for the Romerike Silt Bed chronostratigraphical marker, which is of value for studies in SE Norway and adjacent regions.  相似文献   

Practices in disaster mitigation in the case of the 2015 Typhoon Koppu debris flows in Nueva Ecija,Philippines     

Llanes  Francesca V.  Eco  Rodrigo  Herrero  Tatum Miko  Briones  Jo Brianne Louise  Escape  Carmille Marie  Sulapas  Jolly Joyce  Galang  Jan Albert Macario  Ortiz  Iris Jill  Sabado  Jasmine May  Lagmay  Alfredo Mahar Francisco  Rodolfo  Kelvin 《Natural Hazards》2022,114(1):665-690

Natural Hazards - In October 2015, heavy rains brought by Typhoon Koppu generated landslides and debris flows in the municipalities of Bongabon, Laur, and Gabaldon in Nueva Ecija province....  相似文献   

Prospective modelling of 3D hyporheic exchange based on high‐resolution topography and stream elevation          下载免费PDF全文

Daniel H. Käser  Andrew Binley  Stefan Krause  A. Louise Heathwaite 《水文研究》2014,28(4):2579-2594

River managers and scientists interested in hyporheic processes need adequate tools for characterizing hyporheic exchange flow (HEF) at local sites where only poor information on subsurface properties are available. This study evaluates a three‐dimensional modelling approach, on the basis of detailed surface parameterization and a simplified subsurface structure, for comparison of potential HEF characteristics at three experimental reaches at the channel‐unit scale. First, calibration is conducted to determine the best fit‐of‐heads given the model simplification, then the structure of residuals are used to evaluate the origin of the misfit, and finally, a sensitivity analysis is conducted to identify inter‐site differences in HEF. Results show that such an approach can highlight potential magnitude differences in HEF characteristics between reaches. The sensitivity analysis is successful in delineating the small area of exchange that remains under conditions of high groundwater discharge. In this case, however, the calibrated model performs poorly in representing the exchange pattern at the sediment–water interface, thus suggesting that the approach is less adequate for a deterministic simulation of observed heads. The summary statistics are in the range of similar published models, for which the reported indicator is the root mean square error on heads normalized by the head drop over the reach. We recommend, however, that modellers use a more comparable indicator, such as a measure of the residuals normalized by a measure of observed vertical head differences. Overall, when subsurface data are unavailable or sparse, a three‐dimensional groundwater model based on high‐resolution topographic data combined with a sensitivity analysis appears as a useful tool for a preliminary characterization of HEF. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Up‐scaling potential impacts on water flows from agricultural water interventions: opportunities and trade‐offs in the Osman Sagar catchment,Musi sub‐basin,India     

Kaushal K. Garg  Suhas P. Wani  Jennie Barron  Louise Karlberg  Johan Rockstrom 《水文研究》2013,27(26):3905-3921

Agricultural water management (AWM) has been shown to improve and secure yields in the tropics and has been suggested as an important way to combat poverty in the region. In this paper, we describe potential impacts on upstream and downstream flows of extensive AWM interventions, using the watershed development programme of the Osman Sagar catchment of Musi sub‐basin, Andhra Pradesh semi‐arid India, as an example. Various AWM interventions are compared with a non‐intervention state and the current state of the study area, using 31 years of data by application of the calibrated and validated ARCSWAT 2005 (Version 2.1.4a) modelling tool. Different AWM interventions contribute to improved livelihoods of upstream smallholder farmers by increasing soil moisture availability and groundwater recharge, which can subsequently be used for irrigation. The result is higher crop production and hence larger incomes. Moreover, lower flow intensities and sediment losses reduced by 30–50%, reducing the risk of flooding and sediment accumulation in the Osman Sagar drinking water reservoir. On the other hand, AWM interventions are predicted to result in reduced total water inflows to the Osman Sagar reservoir from 11% of the total annual rainfall (754 mm) recorded at present, to 8% if AWM interventions were implemented at large scale throughout the catchment. A cost–benefit analysis of AWM interventions showed that the highest net economic returns were achieved at intermediate intervention levels (only in‐situ AWM). Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Monochromatic observations of three nebular objects in the direction of NGC 1714     

R. Louise  E. Maurice 《Astrophysics and Space Science》1984,103(1):195-197

Using a CCD as detector, we have observed three nebulosities not yet listed in catalogues; they all present a planetary nebula morphology and are situated in the immediate neighbourhood (less than 3 arc min to the East) of NGC 1714. Observations have been made through interference filters centered on the main emission lines of these objects.The observations were made at the E.S.O. in La Silla (Chile).European Southern Observatory, La Silla, Santrago de Chile.  相似文献   

Sisterhood and Seine‐Nets: Engendering Development and Conservation in Ghana's Marine Fishery     

Barbara Louise Endemao Walker 《The Professional geographer》2001,53(2):160-177

As processors and marketers of fish, women fishtraders in the Fanti town of Cape Coast, Ghana have become powerful financers and owners of canoes, nets, and other fishing equipment. Since the 1960s, when motors were first introduced to Ghana's artisanal canoe fleet, two interrelated processes have occurred in Cape Coast. First, Ghana's fisheries have become increasingly exploited and—in the case of some species—overfished. Second, the social relations of production in the artisanal sector have shifted from being socially embedded to being more market‐based and impersonal. I argue that two recent Women in Development (WID) projects in particular have contributed to the breakdown of fishtraders’ traditional economic networks and livelihood strategies: (a) loan schemes that target women's associations, and (b) the 1985 Intestate Succession Law, which reconfigured inheritance rights. These WID projects, based on western notions of gender and the household, have created disharmony and mistrust among Cape Coast's fishtraders rather than promoting their “development.” The breakdown of fishtraders’ labor and marketing organizations has resulted in increasingly desperate strategies to get fish, increased degradation of Ghana's marine environment, and uncertainty for the future of the coastal economy.  相似文献   

Mid-Holocene Hemlock Decline in Eastern North America Linked with Phytophagous Insect Activity     

Najat Bhiry  Louise Filion 《Quaternary Research》1996,45(3):312-320

Macrofossil evidence indicates that the mid-Holocene hemlock [Tsuga canadensisL. (Carr.)] decline that occurred over a wide area in eastern North America was associated with phytophagous insect activity.In situhemlock macrofossils and insect remains found in a paludified dunefield at the northern limit of hemlock testify that two defoliation events occurred at 4910 ± 90 and 4200 ± 100 yr B.P., respectively. The sharp coincidence of remains from hemlock needles with chewing damage typical of hemlock looper feeding, head capsules from the hemlock looper (Lambdina fiscellaria) and the spruce budworm (Choristoneura fumiferana), absence of hemlock fruiting remains, and tree-ring anomalies in fossil hemlocks that died prematurely (<165 yr) suggest that defoliation affected hemlock reproductive capacity and pollen productivity, or more likely caused mass mortality. Our findings indicate that defoliation can affect ecosystems for centuries, especially when long-lived tree species are involved.  相似文献