Miracle-dz/UniFAR-FTUs huggingface dataset:
A Comparison of 500 hPa Height Patterns Associated With Anticyclones of Pacific and Continental Origin Impacting The Central Gulf Coast, United States

This research examines the 500 hPa circulation patterns that lead to the occurrence of days dominated by anticyclones of Pacific origin ("Pacific Highs") over the central Gulf Coast. Although the geographically preferred zones of greatest height variability are similar to those leading up to days dominated by anticyclones of continental origin ("Continental Highs"), variability centers on the northern fringes of the extratropics seem to support Pacific High activity to a greater extent than was found for Continental High events. The implication is that the presence of strong meridional flow is not necessary to advect a Pacific anticyclone to the Gulf Coast. However, composite flow pattern analysis reveals that slight upstream meridional flow has become more closely associated with Pacific High activity over the Gulf Coast from the 1961-1989 time period. Variability in 500 hPa flow leading up to Pacific High events is tied less directly to variability in surface weather variables than for Continental High events. These results are important because changes in surface atmospheric conditions predicted by GCMs are the result of circulation shifts, and the relationship between upper-level circulation shifts and the surface atmospheric response must be clearly understood.
Effect of buoyancy ratio on the development of double‐diffusive finger convection in a Hele‐Shaw Cell

We consider the evolution of double‐diffusive finger convection for a two‐ solute (salt‐sucrose) system in a Hele‐Shaw cell. A high‐resolution, full‐field, light transmission technique was used to study the development of the instability that resulted from layering a lighter sucrose solution over a denser salt solution. The buoyancy ratio (Rρ), which is a ratio of fluid density contributions by the two solutes and defines the degree of system disequilibrium, was varied systematically from conditions that were nearly stable (Rρ = 2.8) to those that were moderately unstable (Rρ = 1.4). In all experiments, fingers are found to form continuously throughout time from a finger “generation” zone that straddles the location of the initial interface between solutions. At low Rρ, fingers develop rapidly, merge with adjacent fingers, and grow far beyond the finger generation zone through a series of finger “conduits. ” In the higher Rρ experiments, fingers are slower to evolve, do not interact as dynamically, and do not grow far beyond the generation zone. Solute mass fluxes at low Rρ quickly reach a constant many times greater than that of a purely diffusive system; at high Rρ, mass fluxes decay as t−½ and behave diffusively but with effective diffusion coefficients much greater than those for molecular diffusion.
Understanding changes in bird populations – the role of bird marking

Studies of marked birds play a central role in research on avian population dynamics and life histories because they are the main means of estimating survival, recruitment and dispersal. Integrated Population Monitoring aims to combine such information from ringing with data on abundance, productivity and the environment in order to develop population models that address applied questions. Diagnosing the demographic and environmental causes of population declines provides a basis for developing management prescriptions for population recovery. We discuss examples of how such studies are contributing to the conservation of European farmland birds and to understanding declines in Afro–Palaearctic migrants. Adaptive harvest management of North American duck populations demonstrates that similar principles apply to the management of quarry species. Over the next two decades we expect significant advances in our understanding of seasonal variation in demographic rates, of density dependence and of the ways in which continental‐scale population dynamics are built up from processes operating at much smaller spatial scales. This will be achieved through analyses of large‐scale data sets, the combination of conventional and new technologies and the widespread application of fully integrated modelling methods. Large‐scale data gathering through national ringing centres will play a key part in this process.
Internal waves in a small reservoir

Horizontally distributed temperature time series recorded in the thermocline of a small reservoir during autumn are used to identify both basin-scale and higher-frequency internal waves. Stationary and nonstationary spectral analyses are used to identify dominant frequencies. The horizontal distribution of data allows a map of the basin-scale wave energy to be determined. Three-layer normal mode modeling incorporating damping emulates the basin-scale behavior well. This provides estimates of velocity shear and hence the internal stability. The nonstationary frequency analysis identifies times of high-frequency internal wave activity (wave periods of ∼2-10 min). This is definitely linked to the basin-scale wave-driven shear and hence, to deceases in stability. Estimates of dissipation for the thermocline and hypolimnion are 3 × 10 -8 and 6 × 10 -9 m 2 s -3 , respectively. The inferred variability in the hypolimnetic value is demonstrated.
A Numerical Investigation of Formation and Variability of Antarctic Bottom Water off Cape Darnley, East Antarctica

AbstractAt several locations around Antarctica, dense water is formed as a result of intense sea ice formation. When this dense water becomes sufficiently denser than the surrounding water, it descends the continental slope and forms Antarctic Bottom Water (AABW). This study presents the AABW formation off the coast of Cape Darnley [Cape Darnley Bottom Water (CDBW)] in East Antarctica, using a nonhydrostatic model. The model is forced for 8 months by a temporally uniform surface salt flux (because of sea ice formation) estimated from Advanced Microwave Scanning Radiometer for Earth Observing System (EOS; AMSR-E) data and a heat budget calculation. The authors reproduce AABW formation and associated periodic downslope flows of dense water. Descending pathways of dense water are largely determined by the topography; most dense water flows into depressions on the continental shelf, advects onto the continental slope, and is steered downslope to greater depths by the canyons. Intense sea ice formation is the .
Low-cost microsatellite UV instrument suite for monitoring ozone and volcanic sulphur dioxide

The potential of microsatellite instrumentation is analysed in the context of volcanic plume monitoring. In October 1998 the Nyamuragira volcano (Dem. Rep. Congo, Africa) erupted releasing a significant amount of sulphur dioxide (SO2). The Ozone Mapping Detector (OMAD) instrument on-board the FASAT-Bravo microsatellite observed this event as an anomaly in solar backscattered UV. The event was similarly detected by NASA's Total Ozone Mapping Spectrometer (TOMS) with higher wavelength resolution. The response of the two instruments was analysed using instrument models and the MODTRAN radiative transfer code. Good quantitative agreement was observed despite the inherent instrumental differences. Volcanic plume events have been observed before by large space-based instruments, however this is the first such detection by a small, low-cost instrument operating on a microsatellite. Using OMAD as a basis, a new miniaturised UV spectrometer is proposed with the aim of monitoring volcanic-SO2 plumes in the UV region between 305-315 nm, with additional channels at 340 nm and 360 nm for potential aerosol retrievals and processing purposes. This new instrument will use a Silicon Carbide (SiC) detector-array, due to its solar-visible-blind response and its high detectivity. This instrument concept, if flown in a constellation of microsatellites, can augment and complement current missions.
Les dépôts et terrasses fluviatiles d'Aquitaine et du bassin de l'Allier

Les etudes realisees en Aquitaine et dans le bassin de l'Allier montrent qu'il existe une forte correlation entre paleoclimats et facies des depots fluviatiles : les depots a texture fine sont l'expression d'episodes biostasiques, temperes ou temperes frais, les depots a texture grossiere sont l'expression d'episodes rhexistasiques froids. Les phase de creusement vertical des vallees se placent generalement entre deux sequences fluviatiles successives; elles interviennent vraisemblablement au cours des episodes interglaciaires.
Global three-dimensional modeling of the water vapor concentration of the mesosphere-mesopause region and implications with respect to the noctilucent cloud region

A global three-dimensional model of the dynamics (0–150 km) and chemistry (30–150 km) of the middle atmosphere has been developed and applied to the problem of the water vapor distribution of the mesosphere-mesopause region. The mesopause region is one of the most intricate domains of the atmosphere and requires an extraordinarily careful modeling. In order to interpret the specific feature of the water vapor distribution, particular attention was paid to the problem of the effective characteristic chemical time and the comparison of this time with the characteristic transport time. The results confirm measurements which show highest concentrations during the summer months and lowest concentrations in the winter in the middle and high latitudes of the mesosphere because of the seasonal variation of the vertical wind system and change in the altitudes of levels of constant pressure as a result of a mean cooling or warming below the respective heights. The equator region is marked by a semiannual variation with maxima around the equinoxes. By way of contrast, the Halogen Occultation Experiment (HALOE) measurements show maxima around solstices, however, with some exceptions for which a maximum also occurs during the equinox. This points to a dynamically sensitive equatorial region. At high latitudes the extremely low temperatures within the mesopause region in summer and the relatively high water vapor concentrations cause a supersaturation of water vapor which is the condition for the formation of noctilucent clouds (NLCs). The calculated seasonal and latitudinal border of the domain of supersaturation corresponds quite well with the mean areas of the occurrence of NLCs; however, it is impossible to model specific events on the basis of such a coarse model as the occurrence of NLCs at middle latitudes. There is no direct hemispheric transport from the summer to the winter hemisphere within the mesosphere-lower thermosphere, but the meridional transport occurs in a more complicated manner.
Structure and function of TatD exonuclease in DNA repair

TatD is an evolutionarily conserved protein with thousands of homologues in all kingdoms of life. It has been suggested that TatD participates in DNA fragmentation during apoptosis in eukaryotic cells. However, the cellular functions and biochemical properties of TatD in bacterial and non-apoptotic eukaryotic cells remain elusive. Here we show that Escherichia coli TatD is a Mg2+-dependent 3′–5′ exonuclease that prefers to digest single-stranded DNA and RNA. TatD-knockout cells are less resistant to the DNA damaging agent hydrogen peroxide, and TatD can remove damaged deaminated nucleotides from a DNA chain, suggesting that it may play a role in the H2O2-induced DNA repair. The crystal structure of the apo-form TatD and TatD bound to a single-stranded three-nucleotide DNA was determined by X-ray diffraction methods at a resolution of 2.0 and 2.9 Å, respectively. TatD has a TIM-barrel fold and the single-stranded DNA is bound at the loop region on the top of the barrel. Mutational studies further identify important conserved metal ion-binding and catalytic residues in the TatD active site for DNA hydrolysis. We thus conclude that TatD is a new class of TIM-barrel 3′–5′ exonuclease that not only degrades chromosomal DNA during apoptosis but also processes single-stranded DNA during DNA repair.
The thermal structure of subduction zone back arcs

[1] It is well recognized that active arc volcanism at nearly all subduction zones requires temperatures greater than 1200°C in the subarc mantle, despite the underthrusting cool subducting plate. In this study, we document evidence that high upper mantle temperatures are not restricted to the arc but usually extend for several hundred kilometers across the back arc, even in areas that have not undergone extension. For 10 circum-Pacific back arcs where there has been no significant recent extension, we have compiled observational constraints on the thermal structure using a number of independent indicators of mantle temperature, including surface heat flow, seismic velocity, and xenolith thermobarometry. The observations indicate uniformly high temperatures in the shallow mantle and a thin lithosphere (1200°C at ∼60 km depth) over back-arc widths of 250 to >900 km. Similar high temperatures are inferred for extensional back arcs of the western Pacific and southern Europe, but the thermal structures are complicated by extension and spreading. A broad hot back arc may be a fundamental characteristic of a subduction zone that places important constraints on back-arc mantle dynamics. In particular, the thermal structure predicted for slab-driven corner flow is inconsistent with the observed uniformly high back-arc temperatures. We favor the alternate model that heat is rapidly carried upward from depth by vigorous thermal convection in the back-arc upper mantle. Such convection may be promoted by low viscosities, resulting from hydration by fluids from the subducting plate. Following subduction termination, we find that the high temperatures decay over a timescale of about 300 Myr.
Perspective Chapter: Approaches to Quality Assurance and Technological Innovation in Higher Education Institutions

Literature from the wider field of management research is ambiguous with respect to the relationship between quality management and innovation, with some arguing that quality management supports innovation while others claim it is a hindrance. This chapter focuses on the relationship between QA and innovation in higher education, specifically the development of massive-open-online-courses (MOOCs). Analysis of interviews and documents shows that QA does not support innovation; universities focus on the quality of conventional in-person courses, but less on new innovation like MOOCs. The particular characteristics of MOOCs (e.g., diverse learners and light content) make the application of existing QA procedures difficult. Also, analysis shows that the most relevant quality approach for MOOCs is a combination of the conventional approach to QA in higher education and a new QA approach that takes into consideration the characteristics and features of MOOCs. The findings of the study provide suitable empirical evidence to support a cogent argument about the capabilities and qualifications of MOOCs in higher education with regard to QA, further defining the role of MOOCs in higher education.
Vulnerability of water resources, vegetation productivity and soil erosion to climate change in Mediterranean watersheds

Climate change is expected to increase temperatures and lower rainfall in Mediterranean regions; however, there is a great degree of uncertainty as to the amount of change. This limits the prediction capacity of models to quantify impacts on water resources, vegetation productivity and erosion. This work circumvents this problem by analysing the sensitivity of these variables to varying degrees of temperature change (increased by up to 6·4 °C), rainfall (reduced by up to 40%) and atmospheric CO2 concentrations (increased by up to 100%). The SWAT watershed model was applied to 18 large watersheds in two contrasting regions of Portugal, one humid and one semi‐arid; incremental changes to climate variables were simulated using a stochastic weather generator. The main results indicate that water runoff, particularly subsurface runoff, is highly sensitive to these climate change trends (down by 80%). The biomass growth of most species showed a declining trend (wheat down by 40%), due to the negative impacts of increasing temperatures, dampened by higher CO2 concentrations. Mediterranean species, however, showed a positive response to milder degrees of climate change. Changes to erosion depended on the interactions between the decline in surface runoff (driving erosion rates downward) and biomass growth (driving erosion rates upward). For the milder rainfall changes, soil erosion showed a significant increasing trend in wheat fields (up to 150% in the humid watersheds), well above the recovery capacity of the soil. Overall, the results indicate a shift of the humid watersheds to acquire semi‐arid characteristics, such as more irregular river flows and increasingly marginal conditions for agricultural production. Copyright © 2007 John Wiley & Sons, Ltd.
The Capelli problem for $\mathfrak{gl}(m|n)$ and the spectrum of invariant differential operators

The"Capelli problem"for the symmetric pairs $(\mathfrak{gl}\times \mathfrak{gl},\mathfrak{gl})$ $(\mathfrak{gl},\mathfrak{o})$, and $(\mathfrak{gl},\mathfrak{sp})$ is closely related to the theory of Jack polynomials and shifted Jack polynomials for special values of the parameter. In this paper, we extend this connection to the Lie superalgebra setting, namely to the supersymmetric pairs $(\mathfrak{g},\mathfrak{g}):=(\mathfrak{gl}(m|2n),\mathfrak{osp}(m|2n))$ and $(\mathfrak{gl}(m|n)\times\mathfrak{gl}(m|n),\mathfrak{gl}(m|n))$, acting on $W:=S^2(\mathbb C^{m|2n})$ and $\mathbb C^{m|n}\otimes(\mathbb C^{m|n})^*$. We also give an affirmative answer to the abstract Capelli problem for these cases.
A carbon‐isotopic study of an end‐Permian mass‐extinction horizon, Bulla, northern Italy: a negative δ13C shift prior to the marine extinction

Palaeontological data from the Permian‐Triassic Bulla section, northern Italy, demonstrate a rapid extinction at this site. This occurs after a negative carbonate carbon‐isotope (δ13Ccarb) shift, consistent with two other northern Italian sites (Val Badia and Tesero). However, conclusion goes against recent reporting that the extinction occurs before the δ13Ccarb shift. We agree that the shift occurs after the extinction at Jameson Land, east Greenland (a high latitude palaeolocation). However, all other sections show the shift before, or coincident with, the extinction. We suggest that the simplest explanation is a coeval shift in carbonate carbon‐isotope shifts, and it follows that the extinction was not. This suggests that the end‐Permian extinction crept from region to region. It also suggests that the marine extinction occurred first in high northern latitudes.
Propagation analysis of electromagnetic waves between the helium and proton gyrofrequencies in the low‐altitude auroral zone

We present a statistical study of electromagnetic emissions with a lower frequency limitation observed in a broadband below the local proton gyrofrequency. An extensive data set recorded by the low-orbiting Freja satellite is examined. The emissions occur outside the plasmasphere, mainly at auroral latitudes. The maximum wave power is observed before the local noon, and no events have been detected during the local night. In the majority of cases we can assume the presence of a single plane wave. Further analysis shows a nearly circular and right-handed polarization. The statistics of wave vector directions reveal a downward and nearly field aligned propagation. An experimental estimation of the phase velocity modulus is in rough agreement with the cold plasma theory. The origin of the emissions could be possibly explained by the tunnelling of the downgoing ELF hiss below the two-ion cross-over frequency.
Chemical and Thermal Effects on Wellbore Stability of Shale Formations

A new 3D wellbore-stability model includes thermal stresses and the flux of water and solutes into and out of shale formations. Mechanical stresses around a wellbore are coupled with changes in temperature and pore pressure. Radial and azimuthal variation in stress distribution and failure index are computed to check for wellbore failure. Model results show that a pore-pressure maximum or minimum can occur within the shale and can lead to wellbore failure some distance inside the shale. Pore pressures at different times and positions are investigated, and it is shown that critical mud weight is strongly time dependent.
Investigating stress regimes in sedimentary basins using information from oil industry wireline logs and drilling records

Abstract Estimates of the in situ stress tensor in sedimentary basins can be inferred from information gathered during the drilling and logging of hydrocarbon exploration wells. Principal stress magnitudes can be obtained from information provided by density logs, drilling histories, leak-off test results and pore pressure measurements. Horizontal principal stress orientations are indicated by borehole breakouts recorded on four-arm dipmeter logs. The stress magnitude estimates are comparable with values obtained from hydraulic fracturing and the orientation data provide a level of detail hitherto unobtainable. The information obtained assists in designing hydraulic fractures, in secondary recovery programmes and in obtaining optimum drill bit performance. It also contributes to understanding lithospheric plate movements, crustal subsidence and tectonic deformation.
Relationships of Modern Gypsum Nodules in Sabkhas of Loess to Compositions of Brines and Sediments in Northern Egypt

The host sediment is a desert loess, forming a gypsiferous sonochak soil with a thin salt crust. The nodules occur only in areas where the capillary fringe intersects the ground surface, usually where the surface is within 1.5 m of the water table. Nodules a few centimeters beneath the surface are white, very fine grained gypsum. Nodules at lower levels are of more coarsely crystalline gypsum. Phreatic groundwater brines, although saturated for calcium sulfate, are only moderately hypersaline, about 60 per mil. New evidence suggests that they are mainly of marine origin. Surface evaporation causes capillary brines above the water table to move upwards through the loess and to increase in salinity. A marked increase in the m Mg (super 2+) / m Ca (super 2+) ratio of the interstitial brines at the zone of fine-grained nodules demonstrates active precipitation there of calcium sulfate. It is because of the existence of a very high salinity zone (>300 per mil) with halite, at the top of the profile, that gypsum precipitation takes place beneath the surface so as to form nodules rather than a surface crust. Na (super +) and Cl (super -) ions, in addition to Ca (super 2+) and SO 2 (super 2-) ions, seem to be necessary for the development of gypsum nodules by the "per ascensum" mechanism. --Modified journal abstract.