Miracle-dz/UniFAR-FTUs huggingface dataset:
The Effect of Triaxial Stress Systems on the Strength of Rocks at Atmospheric Temperatures

Summary The experimental work described in this paper was carried out in order to discover more about the laws governing the effect of the stress system on brittle fracture, with particular reference to rocks. Consideration of the implications of Griffith's theory of brittle fracture when an arbitrary, uniform plane stress system is applied (Murrell 1964a, b) enabled a number of fracture criteria to be postulated for triaxial stress conditions which required experimental investigation. An apparatus has been built which enables cylindrical rock specimens to be subjected to various combinations of principal stress (tension with compression, triaxial compression with the intermediate principal stress equal either to the major or the minor principal stress) with or without a controlled pore pressure, and at the same time enables the axial and diametral strains to be measured. Confining pressures of up to 4kb can be applied, with pore pressures up to 2kb. A new method of measuring the tensile strength of very brittle materials is described. Experiments were carried out on an isotropic sandstone. It is shown that with one principal stress tensile fracture occurs at a critical value of the tensile stress (=K′) within the range of hydrostatic stresses which were studied. When none of the principal stresses is tensile fracture occurs when the shear stress (τ) on the fracture surface reaches a value which depends on the normal stress (σ) according to the law where λ (4K′)½ and n 0.61. Where pore pressures are applied ‘effective stresses’ must be used in the equation (that is, s must be replaced by σ′=σ+p, where p is the pore pressure). The intermediate principal stress has a slight but measurable effect on the fracture criterion. After fracture the load supported by the rock falls to a value which can be supported by friction between the fracture surfaces. It is found that Amonton's law of friction is not obeyed, and instead the shear stress () due to friction and the normal stress () follow a law where μo 2 and n 0.9. Again ‘effective stresses’ must be used in the equation when pore pressures are applied. Pore water lowers slightly the parameters λ and μo by some form of chemical action. When the shear stress required to cause fracture becomes equal to or less than that required to overcome sliding friction, fracture is no longer possible and there is a transition to ductile behaviour. This occurs at a confining pressure of ∼ 17 000 Lb/in2 (1.17 kb) in the case of the sandstone used in the experiments. Interesting fractures occur sometimes, after the confining pressure is removed, in specimens which have been plastically deformed.
NEW ABSOLUTE TIME SCALE FOR THE QUATERNARY CLIMATE IN THE CHINESE LOESS REGION BY GRAIN-SIZE ANALYSIS

Continuous loess sequences in China provide not only information for paleoclimatic reconstructions, but also permit the establishment of a reliable absolute time scale for the Quaternary. An empirical relationship is developed between the grain size of the loess and the sedimentation rate in a short, well-dated reference section (step 1). This relationship is extrapolated to the complete Quaternary section (step 2). After derivation of the sedimentation rate (by measuring the grain size) in all the layers of the sequence, the duration of deposition of each layer is obtained (by dividing thickness by sedimentation rate) and subsequently the age of each point in the sequence is calculated (by adding together all the duration values of the overlying layers). The chronology of the extrapolated part of the section obtained in this way is independent of dates provided by other methods and may also be checked by them.
Characteristics of the Alaskan 1-Km Advanced Very High Resolution Radiometer data sets used for analysis of vegetation biophysical properties

Introduction . 2 Normalized difference vegetation index . 3 The AVHRR sensors . 4 Data processing Flow . 6 Scene selection . 5 Computation of solar illumination and satellite viewing geometry.5 Radiometric calibration . 7 Geometric registration . 8 Computation of the normalized difference vegetation index.9 Maximum value compositing . 9 Product generation . 11 Methods . 11 Acquisition dates . 11 Satellite scan angle . 12 Solar zenith angle. 12 Cloud cover . 12 Geographic registration . 14 Results . 15 Distribution of acquisition dates. 15 1991 . 15 1992 . 18 1993 . 18 1994 . 21 1995 . 26 1996 . 26 1997 . Satellite scan angle distribution.31 1991 . 34 1992 . 34 1993 . 34 1994 . 42 1995 . 42 1996 . 42 1997 . 42 Solar zenith angle . 45 Cloud cover . 68 Geometric registration errors . 68 Discussion . 72 Conclusion . 83 References . 84
Spatial metrics – useful indicators for society or mainly fun tools for landscape ecologists?

There is a pronounced demand for indicators to measure progress towards policy aims. Further, there is an increasing interest in documenting changes in the surrounding landscapes, and comparing trends of change in space and time, e.g. through landscape monitoring. Based on the theoretical framework of landscape ecology, this has initiated the development of spatial metrics. Typically, remote sensing information, GIS, and spatial metrics are used to provide a range of measures of landscape content and composition assumed to be of importance to various processes, e.g. changes in species distributions. The ability to quantify and compare different landscapes, link spatial patterns to ecological processes, and predict the outcome of different landscape change scenarios is highly desirable in itself. In addition, it is interesting to analyse whether the same measures could be used as indicators to facilitate communication between scientists and policy makers and/or management. However, a review of the current literature suggests that although progress has been made, a number of critical voices have also been raised, in particular questioning the use of spatial metrics in this context. In general, continued effort is therefore required to develop well-functioning landscape indicators.
Perspectives on the Grey Zone of Species Delimitation With Notes on Invertebrates in the Marine Environment

Defining species boundaries, or delimiting species, is a complex and often difficult task. Indeed, when such studies incorporate approaches that consider evolutionary mechanisms, there is much to be learned about species diversity and how the processes that play critical roles in speciation can impact species delineation. In 2021, a virtual workshop on species delimitation was held at the Smithsonian Institution National Museum of Natural History to train natural history scientists and taxonomists on the appropriate analytical tools that can be used to help delimit species when using molecular data. This perspective highlights some of the main themes discussed during that workshop while detailing three processes that can challenge any species delimitation study. Specifically, we discuss incomplete lineage sorting, gene flow, and population structure when delimiting species boundaries using molecular data. We highlight empirical studies and methodological approaches that have successfully met these challenges under various scenarios. Finally, we provide recommendations and considerations for undertaking species delimitation studies in a variety of taxa. To this end, we recommend that taxonomists fully embrace process-based species delimitation, which can provide important insights into speciation in their study systems. For those developing analytical approaches, we hope they consider incorporating less well-known taxa, such as marine invertebrates, into method testing. Marine invertebrates encompass many dark taxa across the tree of life yet represent the majority of animal phyla, many of which are vulnerable to extinction due to global ocean change. Thus, advancing species delimitation to address taxonomic revisions in these organisms will support conservation decisions on keystone ecosystems. Furthermore, the diversity of their life history strategies, the lack of obvious barriers to gene flow in the ocean environment, and their occurrence in isolated habitat patches can better inform our knowledge of speciation and the evolutionary processes that play a role in generating diversity in nature.
Nocturnal Cool Island in the Sahelian city of Ouagadougou, Burkina Faso

Relatively little is known about the urban climate processes of the fastest growing cities in the world today. Described in this paper are urban–rural and intra‐urban variations in air temperature and humidity in one of these cities; Ouagadougou, Burkina Faso. Measurements were collected from car traverses and fixed site measurements during two field studies. The aim of the study was to determine the influence of land use on the urban climate in this hot‐dry region, with a focus on the role of vegetation and of a large centrally located reservoir.
The shear strength of unsaturated soils

The shear strength of an unsaturated soil is written in terms of two independent stress state variables. One form of the shear strength equation isThe transition from a saturated soil to an unsaturated soil is readily visible. A second form of the shear strength equation isHere the independent roles of changes in total stress σ and changes in pore-water pressure uw are easily visualized.Published research literature provides limited data. However, the data substantiate that the shear strength can be described by a planar surface of the forms proposed. A procedure is also outlined to evaluate the pertinent shear strength parameters from laboratory test results.
A natural experiment suggests little direct temperature forcing of the peatland palaeoclimate record

An important uncertainty in the interpretation of peat‐based Holocene climate reconstructions is what aspect of climate is recorded. Testate amoeba palaeoecological records have generally been interpreted in terms of water table depth but an increasing weight of experimental evidence shows that testate amoeba communities may respond to temperature independent of hydrological variability. In most ombrotrophic peatlands, variability in water table depth is driven by a combination of both temperature and precipitation, making it difficult to isolate any direct forcing by temperature. An unusual peatland ecosystem in which water tables are extremely stable offers an approach to this question. If testate amoeba communities show variability through time in these percolation bogs this implies a direct influence of temperature. This study presents a late Holocene testate amoeba record from the Imnati percolation bog in western Georgia. Below a phase of recent eutrophication results show essentially no variability in testate amoeba community composition or inferred water table depth through more than 4 m of peat representing over 2000 years. It is improbable that there has been no temperature variability over this period and the data therefore imply that direct temperature forcing of the palaeoecological record is minimal, at least for this region and time‐scale.
Edge-Diffracted 1-Sec Surface Waves Observed in a Small-Size Intramountain Basin (Colfiorito, Central Italy)

During the Umbria-Marche, central Italy seismic sequence a small-aperture (≈200 m), four-station array was operating in the Colfiorito plain, a few kilometers away from the epicenters of the ML 5.6 and 5.8 mainshocks of 26 September 1997. The array was deployed approximately 500 m from the eastern edge of the basin. We analyze the three-component seismograms of 12 aftershocks, in a magnitude range of 2.5 to 4.1. Amplitudes of the horizontal components are systematically higher than those of the vertical component, with an average horizontal-to-vertical spectral ratio of about 3 at 1 Hz. In this frequency band, earthquake-induced ground shaking is highly coherent across the array. A 1-sec running-window zero-lag cross-correlation algorithm is used to compute apparent velocity and backazimuth of coherent wave trains in the frequency band 0.5 to 2 Hz. Apparent velocity and backazimuth show a different behavior in the first part of the seismograms compared to the late coda. The largest amplitude waves, that is, S waves and early coda, are characterized by low apparent velocities, mostly between 400 and 1200 m/sec. This suggests that, near the rock edge, the most significant part of seismic energy propagates horizontally in the basin. Backazimuth of these low-frequency, coherent wavetrains never coincides with the array-to-source direction. The predominant backazimuth is peaked around N110°, corresponding to the nearest, steep outcrop of the basin edge. The observed 1-sec coherent wave trains are interpreted as locally generated surface waves that are persistently diffracted from the nearby basin edge as long as a significant level of seismic radiation is incident to the bedrock. When the bedrock excitation decreases a much larger variability of both apparent velocity and backazimuth is observed, suggesting that, in the coda, randomly scattered waves within the basin and late arrivals of deeper origin become more important. Multipathing from the source to the site as well as multipathing within the basin are therefore interpreted as the main causes of the observed long-duration, coherent low-frequency basin shaking.
Dolomite‐II: A high‐pressure polymorph of CaMg(CO3)2

We have measured the infrared spectra and x‐ray diffraction of CaMg(CO3)2‐dolomite to pressures of 50 GPa at 300 K. We observe both splittings and disappearances of x‐ray diffraction peaks initiating near 20 GPa, as well as new bands in the infrared spectrum of dolomite. The onset of the changes in both the x‐ray and infrared data appears to be gradual, and thus kinetically impeded: this is consistent with previous shock results. The infrared and x‐ray data are consistent with dolomite adopting a calcite‐III‐like structure. Our results indicate that high‐pressure polymorphism in dolomite could stabilize CaMg(CO3)2 in the deep mantle, and thus that high‐pressure polymorphs of dolomite could represent the main reservoir for carbon storage within Earth's lower mantle.
The Aplication of E-Test On English Subject Using The Model View Controller

The problem that occurs in one of the high schools is that there is no online-based English exam system, and they still use paper for their assessments. This causes teachers to be unable to give exams to students if they do not attend school. The purpose of this research is to create an online exam system to facilitate exam administration using the Model View Controller (MVC) to assess online English exams. The analytical method uses the System Usability Scale (SUS), to collect data using an electronic test (e-Test). Unifield Modeling Language (UML), a visual modeling technique used in designing and building object-oriented software for E-Test applications.The results showed that the use of the E-test application in a comparison class in English subjects could improve student learning outcomes to a higher level, from a score of 81.7 to 90.9. When compared to the control class, there was a slight increase, namely an increase in value from 71.5 to 75.8. This proves that the E-test application is effectively used by students for english subjects.
Potential Erosion in Mining, Oil Palm Plantations, and Watersheds Reforestation Areas

Erosion forecasting is a complex issue generated by numerous causes, the extent of which varies based on the unique area and conditions. Changes in rainfall, land cover, and watershed function are the primary causes of increased erosion. This study aims to scrutinize the actual and potential erosion in the mining area (MA), oil palm plantations (OPP), and watersheds reforestation (WR) in Asoloe, South Konawe, Indonesia. We utilized qualitative research methods and surveys with the USLE model. MA shares the highest actual erosion with 332.30 tons/ha/year, with an average erosion of 27.69 tons/ha/year from 2011 to 2022. Meanwhile, the potential erosion is 4747.19 tons/ha/year, with an average of 395.60 tons/ha/year. In terms of current conditions, 44.6% of rainfall engenders erosion with more than 0.5 t/ha and 33.9% with more than 1 t/ha. This study successfully demonstrates that for given location and area characteristics, high amounts of rainfall and changes in land function eminently affect soil erosion and that the potential erosion changes that occur in the Asoloe watershed every year are exceptionally influenced by changes in land use and land function. Therefore, some mitigation strategies and policies must be taken to reduce the risk of future erosion. Doi: 10.28991/CEJ-2023-09-09-07 Full Text: PDF
Application of Chlorite Geothermometry to Hydrothermal Alteration in Toyoha Geothermal System, Southwestern Hokkaido, Japan

In this study, we applied chemical geothermometers to the estimation of formation temperatures of chlorites from various types of hydrothermally altered rocks in the Toyoha geothermal field, using core samples from six drill holes (TH‐2 to TH‐7) together with wasted ore samples from Toyoha vein‐type ore deposit. Based on the preliminary examination of mineral assemblages by X‐ray powder diffraction and optical microscopy, hydrothermal alteration observed through the drill holes was classified into four types of alteration zones: propylitic, mixed‐layer minerals, kaolin minerals, and ore mineralized zones. The mineral assemblage of the ore mineralized zone observed through TH‐2, TH‐4, and TH‐6 is similar to those of Toyoha ore veins reported previously. The Fe3+/ΣFe ratios of chlorites were determined by X‐ray photoelectron spectroscopy (XPS), in addition to the usual microprobe analyses. The ratios ranged from 0.20–0.26 for chlorites from the propylitic alteration zone and from 0.13 to 0.17 for those from the ore mineralized zone associated with sulfide minerals. After correcting the Fe3+ contents in the octahedral sites of chlorite structures, we obtained acceptable temperatures of the chlorite formation by application of geothermometers, for instance, a similar range of 150–300°C for chlorites from either the propylitic zone or the ore mineralized zone developed through TH‐2, TH‐4, and TH‐6. Chlorites from the ore mineralized zone proximal to the Toyoha deposit are characterized by high Fe and Mn contents compared to the propylitic chlorites, which is similar to the Toyoha vein‐filling chlorites; the formation temperatures were close to both the homogenization temperatures of fluid inclusions and the present subsurface temperatures measured through drill holes. Chlorites from the Toyoha ore veins, however, gave slightly higher formation temperatures (180–350°C) than those of chlorites from the ore mineralized zone in the drill cores. This suggests that several types of hydrothermal alteration occurred at different stages in the Toyoha geothermal field and the composition of product chlorite was controlled not only by the temperature but also the composition of fluid related to the formation. Reliable estimation of temperature for the chlorite formation provides basic information on evaluating correctly other physicochemical conditions prevalent at the formation.
Oil and gas prospecting beneath Precambrian of foreland thrust plates in Rocky Mountains

Only 16 wells in the Rocky Mountain region have drilled through Precambrian rocks to test the 3 to 6 million acres of sedimentary rocks that are concealed and virtually unexplored beneath mountain-front thrusts. One recent test is a major gas discovery, another a development oil well, and over half of the unsuccessful tests had oil or gas shows. These wells have not only set up an exciting play, they have also helped define the structural geometry of the mountain-front thrusts, including the angle of the thrust, the amount of horizontal displacement, and the presence or absence of fault slivers containing overturned Mesozoic or Paleozoic rocks. Important for further geophysical exploration, these wells have provided vital data on seismic velocities in Precambrian rocks. A alysis of these data has stimulated further exploration along the fronts already drilled: in Wyoming, the Emigrant Trail thrust, the Washakie thrust, the Wind River thrust, the thrust at the north end of the Laramie Range, and the Casper arch; in Utah and Colorado, the Uncompahgre and Uinta uplifts. The geologic success of these wells has encouraged leasing and seismic acquisition on every other mountain-front thrust in the Rockies. An unsuccessful attempt to drill through the Arlington thrust of the Medicine Bow Range will probably only momentarily daunt that play, and the attempted penetration of the Axial arch in Colorado has not condemned that area; in fact, another well is being drilled at this time. Untested areas that will be explored in the near future are: in Wyoming, the south flank of the Owl Creek Range, the southwest flank of the Gros Ventre Range, the east and west flanks of the Big Horn Mountains, the west flank of the Big Horn basin, the north flank of the Hanna basin; in Utah, the south flank of the Uinta Mountains; and in Colorado, the White River uplift, the no th flank of North Park basin, and the Front Range.
Petrology of corundum‐spinel‐sapphirine‐anorthite rocks (sakenites) from the type locality in southern Madagascar

‘Sakenites’ constitute a unique association of corundum‐, spinel‐ and sapphirine‐bearing anorthitic to phlogopitic rocks, first described in rocks from an exposure along the beds of the Sakena river to the NW of Ihosy, south Madagascar. The exposure has been revisited and subjected to a detailed petrological and geochemical study. The aluminous anorthitic rocks occur as boudinaged bands and lenses, closely associated with corundum‐, spinel‐ and sapphirine‐bearing phlogopitites, diverse calcsilicate rocks and marbles within a series of biotite‐sillimanite‐cordierite gneisses of the Ihosy granulite unit in the NW of the Pan‐African Bongolava‐Ranotsara shear zone. Bimineralic anorthite + corundum domains preserve the earliest record of a polyphasic evolutionary history that includes two distinct metasomatic episodes. Probable protoliths of these bimineralic rocks were kaolinite‐rich sediments or calcareous bauxites that were altered by Ca or Si infiltration‐metasomatism prior to or coeval with the development of the anorthite‐corundum assemblage. P–T pseudosection modelling of metapelitic gneisses suggests peak‐conditions around 800 °C and 6–7 kbar for the regional high‐grade metamorphism and deformation in the NW part of the Bongolava‐Ranotsara shear zone. The well‐annealed granoblastic‐polygonal textures indicate complete chemical and textural re‐equilibration of the foliated bimineralic rocks during this event. Subsequently, at somewhat lower P–T conditions (750–700 °C, 6 kbar), the influx of Mg‐, Si‐ and K‐bearing fluids into the anorthite‐corundum rocks caused significant metasomatic changes. In zones infiltrated by ‘primary’ potassic fluids, the bimineralic assemblage was completely replaced by phlogopite and Mg‐Al minerals, thereby producing corundum‐, spinel‐ and sapphirine‐bearing phlogopitites. Further advance of the resulting ‘residual’ Mg‐ and Si‐bearing fluids into anorthite‐corundum domains led to partial to complete replacement of corundum porphyroblasts by spinel, spinel + sapphirine or sapphirine, depending on the activities of the solutes. The static textures developed during this second metasomatic episode suggest fluid influx subsequent to intense ductile deformation in the Bongolava‐Ranotsara ductile shear zone c. 530–500 Ma ago.