345 research outputs found
“The Mirror of Desire”: Britomart and Spenserian Perception in The Faerie Queene
In modern usage, “love” and “justice” are terms used to describe universal standards of behavior even though the modern materialist worldview cannot account for such universal, abstract entities. Spenser’s Faerie Queene dramatizes the conceptual origin of these and similar terms in human experience; for, as C.S. Lewis has noted, Spenser’s poetry “Consists in giving an imagined body to the immaterial” (AL 322). Posing an answer to the question of whether these “imagined bodies” reflect an order of being transcending human experience, the romance narrative of Book III argues in the affirmative by demonstrating that universal standards such as love and justice become unintelligible when understood as private expressions of desire. For, if love and justice are conventional expressions of human desire, the drama of Book III is largely concerned with illustrating the ways convention inevitably distorts, restricts, and ultimately destroys human nature. Conversely, Spenser’s knight of chastity represents the indomitable power of nature unleashed in the service of a higher order of love—a standard for which the subjective experience of desire simply cannot account. Beginning with the desiring look in Merlin’s mirror, the alienation Britomart experiences in response to her reflection invokes the perceptual tension existing between self and other. Spenser’s allusion to Narcissus indicates that such subjective dislocation represents a divide insuperable to fallen intellects, yet the legend of chastity establishes love’s transcendent basis upon this very paradox, in the conjunction of opposites reflecting in their complementarity a figuration of universal, providential, order
Cirrus Cloud Seeding has Potential to Cool Climate
Cirrus clouds, thin ice clouds in the upper troposphere, have a net warming effect on Earth s climate. Consequently, a reduction in cirrus cloud amount or optical thickness would cool the climate. Recent research indicates that by seeding cirrus clouds with particles that promote ice nucleation, their lifetimes and coverage could be reduced. We have tested this hypothesis in a global climate model with a state-of-the-art representation of cirrus clouds and find that cirrus cloud seeding has the potential to cancel the entire warming caused by human activity from pre-industrial times to present day. However, the desired effect is only obtained for seeding particle concentrations that lie within an optimal range. With lower than optimal particle concentrations, a seeding exercise would have no effect. Moreover, a higher than optimal concentration results in an over-seeding that could have the deleterious effect of prolonging cirrus lifetime and contributing to global warming
Global streamflow and flood response to stratospheric aerosol geoengineering
Flood risk is projected to increase under future warming climates due to an
enhanced hydrological cycle. Solar geoengineering is known to reduce
precipitation and slow down the hydrological cycle and may therefore be
expected to offset increased flood risk. We examine this hypothesis using
streamflow and river discharge responses to Representative Concentration
Pathway 4.5 (RCP4.5) and the Geoengineering Model Intercomparison Project (GeoMIP) G4
scenarios. Compared with RCP4.5, streamflow on the western sides of Eurasia
and North America is increased under G4, while the eastern sides see a
decrease. In the Southern Hemisphere, the northern parts of landmasses have
lower streamflow under G4, and streamflow of southern parts increases relative to RCP4.5.
We furthermore calculate changes in 30-, 50-, and 100-year flood return periods
relative to the historical (1960–1999) period under the RCP4.5 and G4
scenarios. Similar spatial patterns are produced for each return period,
although those under G4 are closer to historical values than under RCP4.5.
Hence, in general, solar geoengineering does appear to reduce flood risk in
most regions, but the overall effects are largely determined by this
large-scale geographic pattern. Although G4 stratospheric aerosol
geoengineering ameliorates the Amazon drying under RCP4.5, with a weak
increase in soil moisture, the decreased runoff and streamflow leads to an
increased flood return period under G4 compared with RCP4.5.</p
Stabilization of GABAA Receptors at Endocytic Zones Is Mediated by an AP2 Binding Motif within the GABAA Receptor β3 Subunit
The strength of synaptic inhibition can be controlled by the stability and
endocytosis of surface and synaptic GABAA receptors (GABAARs), but the surface
receptor dynamics that underpin GABAAR recruitment to dendritic endocytic
zones (EZs) have not been investigated. Stabilization of GABAARs at EZs is
likely to be regulated by receptor interactions with the clathrin-adaptor AP2,
but the molecular determinants of these associations remain poorly understood.
Moreover, although surface GABAAR downmodulation plays a key role in
pathological disinhibition in conditions such as ischemia and epilepsy,
whether this occurs in an AP2-dependent manner also remains unclear. Here we
report the characterization of a novel motif containing three arginine
residues (405RRR407) within the GABAAR β3-subunit intracellular domain (ICD),
responsible for the interaction with AP2 and GABAAR internalization. When this
motif is disrupted, binding to AP2 is abolished in vitro and in rat brain.
Using single-particle tracking, we reveal that surface β3-subunit-containing
GABAARs exhibit highly confined behavior at EZs, which is dependent on AP2
interactions via this motif. Reduced stabilization of mutant GABAARs at EZs
correlates with their reduced endocytosis and increased steady-state levels at
synapses. By imaging wild-type or mutant super-ecliptic pHluorin-tagged
GABAARs in neurons, we also show that, under conditions of oxygen–glucose
deprivation to mimic cerebral ischemia, GABAARs are depleted from synapses in
dendrites, depending on the 405RRR407 motif. Thus, AP2 binding to an RRR motif
in the GABAAR β3-subunit ICD regulates GABAAR residency time at EZs, steady-
state synaptic receptor levels, and pathological loss of GABAARs from synapses
during simulated ischemia
Limited dispersion and quick degradation of environmental DNA in fish ponds inferred by metabarcoding
Background Environmental DNA (eDNA) metabarcoding is a promising tool for rapid, non‐invasive biodiversity monitoring.
Aims In this study, eDNA metabarcoding is applied to explore the spatial and temporal distribution of fish communities in two aquaculture ponds and to evaluate the detection sensitivity of this tool for low‐density species alongside highly abundant species.
Materials & Methods This study was carried out at two artificially stocked ponds with a high fish density following the introduction and removal of two rare fish species.
Results & Discussion When two rare species were introduced and kept at a fixed location in the ponds, eDNA concentration (i.e., proportional read counts abundance) of the introduced species typically peaked after two days. The increase in eDNA concentration of the introduced fish after 43 hrs may have been caused by increased eDNA shedding rates as a result of fish being stressed by handling, as observed in other studies. Thereafter, it gradually declined and stabilised after six days. These findings are supported by the highest community dissimilarity of different sampling positions being observed on the second day after introduction, which then gradually decreased over time. On the sixth day, there was no longer a significant difference in community dissimilarity between sampling days. The introduced species were no longer detected at any sampling positions on 48 hrs after removal from the ponds. eDNA is found to decay faster in the field than in controlled conditions, which can be attributed to the complex effects of environmental conditions on eDNA persistence or resulting in the vertical transport of intracellular DNA and the extracellular DNA absorbed by particles in the sediment. The eDNA signal and detection probability of the introduced species were strongest near the keepnets, resulting in the highest community variance of different sampling events at this position. Thereafter, the eDNA signal significantly decreased with increasing distance, although the signal increased slightly again at 85 m position away from the keepnets.
Conclusions Collectively, these findings reveal that eDNA distribution in lentic ecosystems is highly localised in space and time, which adds to the growing weight of evidence that eDNA signal provides a good approximation of the presence and distribution of species in ponds. Moreover, eDNA metabarcoding is a powerful tool for detection of rare species alongside more abundant species due to the use of generic PCR primers, and can enable monitoring of spatial and temporal community variance
Estimating CO₂ emissions for 108000 European cities
City-level CO₂ emissions inventories are foundational for supporting the EU's decarbonization goals. Inventories are essential for priority setting and for estimating impacts from the decarbonization transition. Here we present a new CO₂ emissions inventory for all 116572 municipal and local-government units in Europe, containing 108000 cities at the smallest scale used. The inventory spatially disaggregates the national reported emissions, using nine spatialization methods to distribute the 167 line items detailed in the National Inventory Reports (NIRs) using the UNFCCC (United Nations Framework Convention on Climate Change) Common Reporting Framework (CRF). The novel contribution of this model is that results are provided per administrative jurisdiction at multiple administrative levels, following the region boundaries defined OpenStreetMap, using a new spatialization approach
Read counts from environmental DNA (eDNA) metabarcoding reflect fish abundance and biomass in drained ponds.
The sampling of environmental DNA (eDNA) coupled with cost-efficient and ever-advancing sequencing technology is propelling changes in biodiversity monitoring within aquatic ecosystems. Despite the increasing number of eDNA metabarcoding approaches, the ability to quantify species biomass and abundance in natural systems is still not fully understood. Previous studies have shown positive but sometimes weak correlations between abundance estimates from eDNA metabarcoding data and from conventional capture methods. As both methods have independent biases a lack of concordance is difficult to interpret. Here we tested whether read counts from eDNA metabarcoding provide accurate quantitative estimates of the absolute abundance of fish in holding ponds with known fish biomass and number of individuals. Environmental DNA samples were collected from two fishery ponds with high fish density and broad species diversity. In one pond, two different DNA capture strategies (on-site filtration with enclosed filters and three different preservation buffers versus lab filtration using open filters) were used to evaluate their performance in relation to fish community composition and biomass/abundance estimates. Fish species read counts were significantly correlated with both biomass and abundance, and this result, together with information on fish diversity, was repeatable when open or enclosed filters with different preservation buffers were used. This research demonstrates that eDNA metabarcoding provides accurate qualitative and quantitative information on fish communities in small ponds, and results are consistent between different methods of DNA capture. This method flexibility will be beneficial for future eDNA-based fish monitoring and their integration into fisheries management
Extreme temperature and precipitation response to solar dimming and stratospheric aerosol geoengineering
We examine extreme temperature and precipitation under two
potential geoengineering methods forming part of the Geoengineering Model
Intercomparison Project (GeoMIP). The solar dimming experiment G1 is designed
to completely offset the global mean radiative forcing due to a
CO2-quadrupling experiment (abrupt4  ×  CO2), while in
GeoMIP experiment G4, the radiative forcing due to the representative
concentration pathway 4.5 (RCP4.5) scenario is partly offset by a simulated
layer of aerosols in the stratosphere. Both G1 and G4 geoengineering
simulations lead to lower minimum temperatures (TNn) at higher latitudes and
on land, primarily through feedback effects involving high-latitude processes
such as snow cover, sea ice and soil moisture. There is larger cooling of TNn
and maximum temperatures (TXx) over land compared with oceans, and the
land–sea cooling contrast is larger for TXx than TNn. Maximum 5-day
precipitation (Rx5day) increases over subtropical oceans, whereas warm spells
(WSDI) decrease markedly in the tropics, and the number of consecutive dry
days (CDDs) decreases in most deserts. The precipitation during the tropical
cyclone (hurricane) seasons becomes less intense, whilst the remainder of the
year becomes wetter. Stratospheric aerosol injection is more effective than
solar dimming in moderating extreme precipitation (and flooding). Despite the
magnitude of the radiative forcing applied in G1 being ∼  7.7 times
larger than in G4 and despite differences in the aerosol chemistry and
transport schemes amongst the models, the two types of geoengineering show
similar spatial patterns in normalized differences in extreme temperatures
changes. Large differences mainly occur at northern high latitudes, where
stratospheric aerosol injection more effectively reduces TNn and TXx. While
the pattern of normalized differences in extreme precipitation is more
complex than that of extreme temperatures, generally stratospheric aerosol
injection is more effective in reducing tropical Rx5day, while solar dimming
is more effective over extra-tropical regions.</p
No evidence of break-up effects on the fusion of 9Be with medium-light nuclei
AbstractFusion cross sections were measured for the 9Be+27Al and 19F+9Be, 12C systems, at energies above the Coulomb barrier, in order to investigate the possible effect of fusion hindrance due to the break-up of the weakly bound nuclei. Comparisons with one-dimensional barrier penetration models and with other similar systems, where no break-up is expected to occur, show no evidence of fusion hindrance
- …