7,132 research outputs found
Case Studies of Dewatering and Foundation Design: Retail Warehouses in Taiwan
The case studies in this paper describe three retail warehouse sites in Taiwan that have high groundwater tables in common, but that have drastically different soil conditions. Two of the sites are in dense, permeable gravel and cobble and the third site is in interbedded alluvial sand and clay. At the first site, shallow footings and slab-on-grade floors were placed on top of a permanent passive drainage system that required accurate seepage volume estimates in the permeable gravel and cobble. At the second site, the hydraulic conductivity of the gravel and cobble is high and is sensitive to fluctuation of the regional groundwater table. A hybrid passive drainage and structural slab system minimizes pumping during the seasonal high groundwater table. At the third site, deep slurry walls constructed around the building cut off groundwater seepage, and permanent pumping wells within the building footprint lower the groundwater table. This system also eliminated the risk of soil liquefaction and allowed shallow footings and slab-on-grade floors to be used. This paper discusses the hydrogeological analysis of the three sites and the geotechnical design considerations for the dewatering and foundation systems, as well as soil liquefaction mitigation
Palynostratigraphy of the Eocene Little River Section, Grays Harbor County, Washington
A total of 27 samples from Eocene marine rocks exposed along the Little River, Grays Harbor County, southwestern Washington were analyzed for palynomorphs. Strata studied included the Crescent Formation, Sedimentary Rocks of Late Eocene Age , and the Lincoln Creek Formation. A total of 77 micro fossil types were identified of which 32 were pollen and spores, 24 fungal remains, 18 dinoflagellate cysts, and 3 miscellaneous micro fossils.
Based upon the stratigraphic distribution of 21 palynomorphs, three informal palynologic assemblage biozones were recognized. The oldest zone, Zone 1, of late early or early middle Eocene age, contains Platycaryapollenites, Platanoidites, Laevigatosporites type-2, trilete type-2 and D-6 dinoflagellates. Zone 2, of middle Eocene age, is recognized by the presence of Proteacidites Laevigatosporites type-2, tricolpate reticulate type-1,trilete type-2, and D-14 and D-15 dinoflagellates. Zone 3, of late Eocene age, is recognized by Tsugapollenites, Bombacacidites, Tiliaepollenites, Selaginella, Inaperturopollenites type-2, and D-8 dinoflagellates. None of the palynozones established by previous Pacific Northwest palynologic investigations were recognized in this study
Application of B-splines to determining eigen-spectrum of Feshbach molecules
The B-spline basis set method is applied to determining the rovibrational
eigen-spectrum of diatomic molecules. A particular attention is paid to a
challenging numerical task of an accurate and efficient description of the
vibrational levels near the dissociation limit (halo-state and Feshbach
molecules). Advantages of using B-splines are highlighted by comparing the
performance of the method with that of the commonly-used discrete variable
representation (DVR) approach. Several model cases, including the Morse
potential and realistic potentials with 1/R^3 and 1/R^6 long-range dependence
of the internuclear separation are studied. We find that the B-spline method is
superior to the DVR approach and it is robust enough to properly describe the
Feshbach molecules. The developed numerical method is applied to studying the
universal relation of the energy of the last bound state to the scattering
length. We numerically illustrate the validity of the quantum-defect-theoretic
formulation of such a relation for a 1/R^6 potential.Comment: submitted to can j phys: Walter Johnson symposu
Sea anemones may thrive in a high CO2 world
Increased seawater pCO 2, and in turn 'ocean acidification' (OA), is predicted to profoundly impact marine ecosystem diversity and function this century. Much research has already focussed on calcifying reef-forming corals (Class: Anthozoa) that appear particularly susceptible to OA via reduced net calcification. However, here we show that OA-like conditions can simultaneously enhance the ecological success of non-calcifying anthozoans, which not only play key ecological and biogeochemical roles in present day benthic ecosystems but also represent a model organism should calcifying anthozoans exist as less calcified (soft-bodied) forms in future oceans. Increased growth (abundance and size) of the sea anemone (Anemonia viridis) population was observed along a natural CO 2 gradient at Vulcano, Italy. Both gross photosynthesis (P G) and respiration (R) increased with pCO 2 indicating that the increased growth was, at least in part, fuelled by bottom up (CO 2 stimulation) of metabolism. The increase of P G outweighed that of R and the genetic identity of the symbiotic microalgae (Symbiodinium spp.) remained unchanged (type A19) suggesting proximity to the vent site relieved CO 2 limitation of the anemones' symbiotic microalgal population. Our observations of enhanced productivity with pCO 2, which are consistent with previous reports for some calcifying corals, convey an increase in fitness that may enable non-calcifying anthozoans to thrive in future environments, i.e. higher seawater pCO 2. Understanding how CO 2-enhanced productivity of non- (and less-) calcifying anthozoans applies more widely to tropical ecosystems is a priority where such organisms can dominate benthic ecosystems, in particular following localized anthropogenic stress. Ā© 2012 Blackwell Publishing Ltd
Aging and memory phenomena in magnetic and transport properties of vortex matter: a brief review
There is mounting experimental evidence that strong off-equilibrium
phenomena, such as ``memory'' or ``aging'' effects, play a crucial role in the
physics of vortices in type II superconductors. We give a short review, based
on a recently introduced schematic vortex model, of current progresses in
understanding out of equilibrium vortex behaviours. We develop a unified
description of ``memory'' phenomena in magnetic and transport properties, such
as magnetisation loops and their ``anomalous'' 2nd peak, logarithmic creep,
``anomalous'' finite creep rate in the limit of vanishing temperature,
``memory'' and ``irreversibility'' in I-V characteristics, time dependent
critical currents, ``rejuvenation'' and ``aging'' of the system response.Comment: updated versio
The Killing of African Trypanosomes by Ethidium Bromide
Introduced in the 1950s, ethidium bromide (EB) is still used as an anti-trypanosomal drug for African cattle although its mechanism of killing has been unclear and controversial. EB has long been known to cause loss of the mitochondrial genome, named kinetoplast DNA (kDNA), a giant network of interlocked minicircles and maxicircles. However, the existence of viable parasites lacking kDNA (dyskinetoplastic) led many to think that kDNA loss could not be the mechanism of killing. When recent studies indicated that kDNA is indeed essential in bloodstream trypanosomes and that dyskinetoplastic cells survive only if they have a compensating mutation in the nuclear genome, we investigated the effect of EB on kDNA and its replication. We here report some remarkable effects of EB. Using EM and other techniques, we found that binding of EB to network minicircles is low, probably because of their association with proteins that prevent helix unwinding. In contrast, covalently-closed minicircles that had been released from the network for replication bind EB extensively, causing them, after isolation, to become highly supertwisted and to develop regions of left-handed Z-DNA (without EB, these circles are fully relaxed). In vivo, EB causes helix distortion of free minicircles, preventing replication initiation and resulting in kDNA loss and cell death. Unexpectedly, EB also kills dyskinetoplastic trypanosomes, lacking kDNA, by inhibiting nuclear replication. Since the effect on kDNA occurs at a >10-fold lower EB concentration than that on nuclear DNA, we conclude that minicircle replication initiation is likely EB's most vulnerable target, but the effect on nuclear replication may also contribute to cell killing
MHC immunoevasins: protecting the pathogen reservoir in infection
Alteration of antigen recognition by T cells as result of insufficient major histocompatibility complex (MHC)-dependent antigen-presenting function has been observed in many cases of infections, particularly in in vitro systems. To hide themselves from an efficient immune response, pathogens may act on MHC-related functions at three levels: (i) by limiting the number of potential antigens that can be presented to naive T cells; (ii) by synthesizing proteins which directly affect MHC cell-surface expression; and (iii) by altering the normal intracellular pathway of peptide loading on MHC. Here, we review examples of pathogens' action on each single step of MHC function and we suggest that the result of these often synergistic actions is both a limitation of the priming of naive T cells and, more importantly, a protection of the pathogen's reservoir from the attack of primed T cells. The above mechanisms may also generate a skewing effect on immune effector mechanisms, which helps preserving the reservoir of infection from sterilization by the immune system
Creatine Monohydrate Supplementation Increases White Adipose Tissue Mitochondrial Markers in Male and Female Rats in a Depot Specific Manner
White adipose tissue (WAT) is a dynamic endocrine organ that can play a significant role in thermoregulation. WAT has the capacity to adopt structural and functional characteristics of the more metabolically active brown adipose tissue (BAT) and contribute to non-shivering thermogenesis under specific stimuli. Non-shivering thermogenesis was previously thought to be uncoupling protein 1 (UCP1)-dependent however, recent evidence suggests that UCP1-independent mechanisms of thermogenesis exist. Namely, futile creatine cycling has been identified as a contributor to WAT thermogenesis. The purpose of this study was to examine the efficacy of creatine supplementation to alter mitochondrial markers as well as adipocyte size and multilocularity in inguinal (iWAT), gonadal (gWAT), and BAT. Thirty-two male and female Sprague-Dawley rats were treated with varying doses (0 g/L, 2.5 g/L, 5 g/L, and 10 g/L) of creatine monohydrate for 8 weeks. We demonstrate that mitochondrial markers respond in a sex and depot specific manner. In iWAT, female rats displayed significant increases in COXIV, PDH-E1alpha, and cytochrome C protein content. Male rats exhibited gWAT specific increases in COXIV and PDH-E1alpha protein content. This study supports creatine supplementation as a potential method of UCP1-independant thermogenesis and highlights the importance of taking a sex-specific approach when examining the efficacy of browning therapeutics in future research.Brock Library Open Access Publishing Fun
Radiometric Stability of the SABER Instrument
The SABER instrument on the National Aeronautics and Space Administration ThermosphereāIonosphereāMesosphere Energetics and Dynamics satellite continues to provide a longāterm record of Earth\u27s stratosphere, mesosphere, and lower thermosphere. The SABER data are being used to examine longāterm changes and trends in temperature, water vapor, and carbon dioxide. A tacit, central assumption of these analyses is that the SABER instrument radiometric calibration is not changing with time; that is, the instrument is stable. SABER stratospheric temperatures and those derived from Global Positioning System Radio Occultation measurements are compared to examine SABER\u27s stability. Global Positioning System Radio Occultation measurements are inherently stable due to the accuracy and traceability of the measured phase delay rate to the SystĆØme Internationale definition of the second. Differences in global annual mean SABER and COSMIC lower stratospheric temperatures show little significant change with time in the 11 years spanning 2007ā2017. From this analysis we infer that SABER temperatures are stable to better than 0.1 to 0.2 K per decade
Improving the energy performance of UK households: Results from surveys of consumer adoption and use of low- and zero carbon technologies
This paper presents results from a UK Open University project which surveyed consumers' reasons for adoption, and non-adoption, of energy efficiency measures and renewable energy systemsācollectively called low- and zero-carbon technologiesāand their experiences of using these technologies. Data were gathered during 2006 via an online questionnaire with nearly 400 responses, plus 111 in-depth telephone interviews. The respondents were mainly environmentally concerned, 'green' consumers and therefore these are purposive rather than representative surveys. The paper outlines results for four energy efficiency measures (loft insulation, condensing boilers, heating controls and energy-efficient lighting) and four household renewables (solar thermal water heating, solar photovoltaics, micro-wind turbines and wood-burning stoves). These green consumers typically adopted these technologies to save energy, money and/or the environment, which many considered they achieved despite rebound effects. The reasons for considering but rejecting these technologies include the familiar price barriers, but there were also other obstacles that varied according to the technology concerned. Nearly a third of the surveyed consumers had adopted household renewables, over half of which were wood stoves and 10% solar thermal water heating systems. Most adopters of renewables had previously installed several energy efficiency measures, but only a fifth of those who seriously considered renewables actually installed a system. This suggests sell energy efficiency first, then renewables. There seems to be considerable interest in household renewables in the UK, especially among older, middle-class green consumers, but so far only relatively few pioneers have managed to overcome the barriers to adoption
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