Miracle-dz/UniFAR-FTUs huggingface dataset:
Crustal growth in West Africa at 2.1 Ga

Birimian (∼2.1 Ga) terranes in the West African craton are a mixture of highly metamorphosed volcanic, sedimentary and plutonic rocks and low grade metavolcanics and metasediments. The volcanic units contain thick, commonly pillowed, tholeiitic basalts overlain by pelagic sediments cherts and black shales; The sedimentary units are characterized by an abundance of clastic turbiditic sediments. Andesites and calc-alkaline felsic volcanics occur at uppermost stratigraphic levels and as dykes. Field relationships between the volcanic and sedimentary units remain a matter of debate. Calc-alkaline and local alkaline granites, which intruded in distinct pulses and occasionally are related to transcurrent tectonics, represent almost half of the Birimian terranes. New isotopic work on the highly metamorphosed units greatly improved the chronology for the Birimian crust. The age of the early Dabakalian event is precisely defined by a U-Pb zircon age at 2186 ± 19 Ma, while Rb-Sr and Sm-Nd methods give ages of 2162 ± 19 Ma and 2141 ± 24 Ma, respectively. A Sm-Nd garnet-whole rock age of 2153 ± 13 Ma suggests that metamorphism culminated at about the same time. In contrast, the most precise zircon U-Pb and Sm-Nd data for the more widespread Birimian terranes (sensu stricto), from this study and from the literature, cluster between 2.12 and 2.07 Ga. The major evolution of the Birimian crust apparently lasted less than 50 Ma. Isotopic evidence indicates that Birimian granitoids contain a negligible component of Archean crust: eNd(2.1-Ga) values are positive and similar to those of Birimian basalts, crustal residence times are shorter than 200 Ma, U-Pb ages for detrital zircons from clastic sediments range from 2098 ±11 Ma to 2125 ± 17 Ma, while granite chemistry and Nd isotopic characteristics are unrelated. Only very locally in Guinea is there isotopic evidence of interaction between Birimian felsic magmas and the Archean rocks from the Man craton. In accord with Abouchami et al.'s (1990) suggestion that Birimian basalts represent oceanic plateaus, the present data argue that the protolith of much of the West African continent was created around 2.1 Ga in an environment remote from Archean crust. Intrusion of calc-alkaline magmas into the tholeiitic units suggests that island arcs formed on top of the assumed oceanic plateaus which then collided with the Man Archean craton. Taking the Birimian formations from the Guyana shield into account, the minimum crustal growth rate at 2.1 Ga is about 1.6 km3/a, some ∼60% higher than the present growth rate. Birimian crust growth at 2.1 Ga is reminiscent of Archean processes but contrasts with 1.7 – 1.9 Ga crust formation in the North Atlantic continent which generally involved significantly more interaction with older continental crust. A comparison of the Birimian crustal growth rate with the average crustal growth rate over the Earth history implies that a large part of the Birimian crust has been recycled into the mantle or incorporated into younger orogenic segments. This apparent deficit in the crustal budget is even more dramatic for the Archean crust.
Propagation and linkage of oceanic ridge segments

We have investigated the propagation of spreading ridges and the development of structures that link ridge segments using an analogy between ridges and cracks in elastic plates. The ridge-propagation force and a path factor that controls propagation direction were calculated for echelon ridge segments propagating toward each other. The ridge-propagation force increases as ridge ends approach but then declines sharply as the ends pass, so ridge segments may overlap somewhat. The sign of the path factor changes as ridge ends approach and pass, so the overlapping ridge ends may diverge and then converge following a hook-shaped path. The magnitudes of shear stresses in the plane of the plate and orientations of maximum shear planes between adjacent ridge segments were calculated to study transform faulting. For different loading conditions simulating ridge push, plate pull, and ridge suction, we identify a zone of intense mechanical interaction between adjacent ridge ends in which stresses are concentrated. For all conditions, the shear stress in the interaction zone increases as ends approach and remains large as the ends overlap; thus crust in this zone may fracture and weaken in preparation for the formation of a through-going transform fault. The calculated shear planes rotate toward an orientation about 90° from the strike of ridges as the ends pass, thus favoring the orthogonal arrangement of ridges and transforms. The magnitudes of mean stresses in the plane of the plate and orientations of principal stress planes were also calculated. The mean stress is tensile in the interaction zone, so basins may form there, except in the case of ridge push loading. The planes across which the maximum tension acts are oblique to ridges, thus favoring obliquely oriented normal faults bounding the transform valley.
Experimental Investigation and CFD Modeling of Slush Cryogen Flow Measurement Using Circular Shape Capacitors

The measurement of two-phase cryogenic fluid mixtures flow, also known as slush cryogen flow, with its most attractive form (liquid and solid) is of great interest for various applications, due to its thermodynamic advantages. This paper presents a newly developed device, under the form of a circular capacitor prototype, together with an experimental stand for slush formation. Slush nitrogen was used as testing fluid during the experimental work. Then, the experimental data for slush cryogen flow measurement using the proposed circular shape capacitor were compared with theoretical results obtained by simulation. A three-dimensional flow field model was built and solved for the innovative design slush flowmeter using a computational fluid dynamic (CFD) model. Nitrogen slush density of 874 kg/m3, representing approximately 30% solid fraction, was reported for both the modeling and experimental testing, although the numerical investigation is not limited to these values. By comparing experimental vs. simulation results, a deeper view on the designed configuration can be achieved, thus improving the progress in producing high-performance next generation devices for two-phase flow measurement in terms of physical dimensions, length and space between armatures. Even so, the mathematical model has limitations when mixtures with higher percentages of solid phase and particle sizes are encountered.
Evaluation of heavy metal accumulation in greenhouse soils in Shenyang, Northeast China

Soil heavy metals are considered being originated from two major sources, natural and anthropogenic. With the spring-up of greenhouse farming in the suburbs of big cities, heavy metals accumulation in greenhouse soil is becoming a serious environmental problem. In order to evaluate and ascertain the accumulation status and origins of heavy metals in the greenhouse soils of Shenyang suburb, the Cu, Zn, Cd, As, Cr and Pb contents in soil samples collected from the greenhouse fields with different cultivation years were determined by using atomic absorption spectroscopy (AAS) and hydrogen-atomic fluorescence spectrometer (HG-AFS), and the origins of these heavy metals were analyzed by employing correlation analysis, principle component analysis (PCA) and hierarchical cluster analysis (HCA). No obvious soil heavy metals accumulation was observed, but the Cu, Zn, Cd and As contents in greenhouse soils increased with increasing years of cultivation. Two significant components were extracted by PCA, explaining 70.013% of total variance. The Cu, Zn, Cd and As in test soils were mainly associated with anthropogenic input, whereas Cr and Pb were related to parent rocks. HCA confirmed and completed the results obtained by PCA, classifying the data in two groups representing different origins. Cluster included Cu, Zn, Cd and As representing human inputs, while Cluster included Cr and Pb representing natural sources. Moreover, the results obtained by the correlation analysis also agreed with PCA and HCA, also helping in elucidating the relationship between heavy metals and soil properties. More attention should be paid to the anthropogenic inputs of Cu, Zn, Cd and As in Shenyang greenhouse fields, especially for those having been cultivated for 5 years or more.
Multistage volcanic events: tephra hazard simulations for the Okataina Volcanic Center, New Zealand

[1] While volcanic events are commonly characterized by multiple eruptive stages, most probabilistic tephra hazard analyses only simulate the major (paroxysmal) stage. In this study, we reconsider this simplified treatment by comparing hazard outcomes from simulated single- and multistage eruption sequences, using the Okataina Volcanic Center (OVC) in New Zealand as a case study. Our study draws upon geological evidence particular to the OVC as well as generalized patterns of eruptive behavior from other analogous volcanic centers. Exceedance probabilities of simulated tephra thickness, the cumulative duration of explosive behavior, and the duration of the entire eruptive sequence were all compared. Multistage simulations show an increased hazard with the greatest differences lying close to the vent for long duration and high thickness thresholds and at intermediate distances between the vent and the maximum extent of the deposit for lower thickness and duration thresholds. Multiple explosive stages increase the likelihood of an event lasting longer than 1 month by up to sevenfold and, for given low-probability events, accumulated tephra thicknesses in some locations may increase by 1 order of magnitude and impact up to 22% more of New Zealand's North Island. Given our understanding of the eruptive history of the Okataina Volcanic Center, multistage simulations provide a better understanding of the potential hazard from this source.
Estimating the size and timing of maximum amplitude for cycle 23 from its early cycle behavior

On the basis of the lowest observed smoothed monthly mean sunspot number, cycle 23 appears to have conventionally begun in May 1996, in conjunction with the first appearance of a new cycle, high-latitude spot group. Such behavior, however, is considered rather unusual, since, previously (based on the data-available cycles 12–22), the first appearance of a new cycle, high-latitude spot group has always preceded conventional onset by at least 3 months. Furthermore, accepting May 1996 as the official start for cycle 23 poses a dilemma regarding its projected size and timing of maximum amplitude. Specifically, from the maximum-minimum and amplitude-period relationships we infer that cycle 23 should be above average in size and a fast riser, with maximum amplitude occurring before May 2000 (being in agreement with projections for cycle 23 based on precursor information), yet from its initial languid rate of rise (during the first 6 months of the cycle) we infer that it should be below average in size and a slow riser, with maximum amplitude occurring after May 2000. The dilemma vanishes, however, when we use a slightly later-occurring onset. For example, using August 1996, a date associated with a local secondary minimum prior to the rapid rise that began shortly thereafter (in early 1997), we infer that the cycle 23 rate of rise is above that for the mean of cycles 1–22, the mean of cycles 10–22 (the modern era cycles), the mean of the modern era “fast risers,” and the largest of the modern era “slow risers” (i.e., cycle 20), thereby suggesting that cycle 23 will be both fast rising and above average in size, peaking before August 2000. Additionally, presuming cycle 23 to be a well-behaved fast-rising cycle (regardless of whichever onset date is used), we also infer that its maximum amplitude likely will measure about 144.0 ± 28.8 (from the general behavior found for the bulk of modern era fast risers; i.e., 5 of 7 have had their maximum amplitude to lie within 20% of the mean curve for modern era fast risers). It is apparent, then, that sunspot number growth during 1998 will prove crucial for correctly establishing the size and shape of cycle 23.
Determination of Indoor Climate Requirements of Greenhouses in Samsun Provinces with –GIS assisted / Samsun İl Ve İlçelerinde Seraların İklimsel İhtiyaçlarının Cografi Bilgi Sistemleri İle Belirlenmesi

ABSTRACT: In this study, the most suitable growing period was explored in order to continue production economically in greenhouses. Based on the climatic data gathered from 9 different district of Samsun provinces the time periods for cooling, heating and natural ventilation were determined and compared with each other. Spatially distributions of mean daily outside temperature in region of Samsun determined using DEM (Digital Elevaluation Model) and spatial distributions of heating requirements of greenhouses determined using IDW(Inverse Distance Weight), with support of GIS (Geographic Information system). Research results showed that the central district of Samsun had more advantages in aspects of greenhouse production compared to other districts and Carsamba, Bafra, Kolay, Taflan and Vezirkopru followed it. Unlikely Ladik, Havza and Kavak had several disadvantages for production in greenhouses. Key words: Greenhouses, climatologic requirements, ventilation, heating, cooling, GIS Samsun Il Ve Ilcelerinde Seralarin Iklimsel Ihtiyaclarinin Cografi Bilgi Sistemleri Ile Belirlenmesi OZET: Bu calismada, Samsun il ve ilcelerinde ekonomik olarak seracilik yapilmasi icin iklim parametreleri goz onune alinarak en uygun yetistirme periyotlari belirlenmistir. Calismada, 9 ilcenin iklim verileri kullanilmis, isitma, dogal havalandirma, sogutma gerektiren aylar belirlenmis ve Samsun merkez ilce ile karsilastirilmistir. Samsun il ve ilcelerinin seracilik acisindan gunluk ortalama sicaklik degerlerin uzaysal dagilimi Sayisal Yukseklik Modeli (DEM) kullanilarak, isi gereksinimleri ise Ters Mesafe Agirlikli Enterpolasyon Teknigi (IDW) ile belirlenmistir. Seracilik acisindan en avantajli ilce merkez ilce olup bunu, Carsamba, Bafra, Kolay, Taflan ve Vezirkopru izlerken seracilik acisindan digerlerine gore dezavantajli Ladik, Havza ve Kavak ilceleri bulunmustur Anahtar Kelimeler: Seralar, iklimlendirme istekleri, havalandirma, isitma, sogutma, CBS
Chronological refinement of an ice core record at Upper Fremont Glacier in south central North America

The potential to use ice cores from alpine glaciers in the midlatitudes to reconstruct paleoclimatic records has not been widely recognized. Although excellent paleoclimatic records exist for the polar regions, paleoclimatic ice core records are not common from midlatitude locations. An ice core removed from the Upper Fremont Glacier in Wyoming provides evidence for abrupt climate change during the mid-1800s. Volcanic events (Krakatau and Tambora) identified from electrical conductivity measurements (ECM) and isotopic and chemical data from the Upper Fremont Glacier were reexamined to confirm and refine previous chronological estimates of the ice core. At a depth of 152 m the refined age-depth profile shows good agreement (1736{+-}10 A.D.) with the {sup 14}C age date (1729{+-}95 A.D.). The {delta}{sup 18}O profile of the Upper Fremont Glacier (UFG) ice core indicates a change in climate known as the Little Ice Age (LIA). However, the sampling interval for {delta}{sup 18}O is sufficiently large (20 cm) such that it is difficult to pinpoint the LIA termination on the basis of {delta}{sup 18}O data alone. Other research has shown that changes in the {delta}{sup 18}O variance are generally coincident with changes in ECM variance. The ECM data set contains over 125,000 data points atmore » a resolution of 1 data point per millimeter of ice core. A 999-point running average of the ECM data set and results from f tests indicates that the variance of the ECM data decreases significantly at about 108 m. At this depth, the age-depth profile predicts an age of 1845 A.D. Results indicate the termination of the LIA was abrupt with a major climatic shift to warmer temperatures around 1845 A.D. and continuing to present day. Prediction limits (error bars) calculated for the profile ages are {+-}10 years (90% confidence level). Thus a conservative estimate for the time taken to complete the LIA climatic shift to present-day climate is about 10 years, suggesting the LIA termination in alpine regions of central North America may have occurred on a relatively short (decadal) timescale. (c) 2000 American Geophysical Union. « less
Land cover classification using high‐resolution aerial photography in adventdalen, svalbard

Abstract A methodology was tested for high‐resolution mapping of vegetation and detailed geoecological patterns in the Arctic Tundra, based on aerial imagery from an unmanned aerial vehicle (visible wavelength – RGB, 6 cm pixel resolution) and from an aircraft (visible and near infrared, 20 cm pixel resolution). The scenes were fused at 10 and 20 cm to evaluate their applicability for vegetation mapping in an alluvial fan in dventdalen, Svalbard. Ground‐truthing was used to create training and accuracy evaluation sets. Supervised classification tests were conducted with different band sets, including the original and derived ones, such as and principal component analysis bands. The fusion of all original bands at 10 cm resolution provided the best accuracies. The best classifier was systematically the maximum neighbourhood algorithm, with overall accuracies up to 84%. Mapped vegetation patterns reflect geoecological conditioning factors. The main limitation in the classification was differentiating between the classes graminea, moss and Salix, and moss, graminea and Salix, which showed spectral signature mixing. Silty‐clay surfaces are probably overestimated in the south part of the study area due to microscale shadowing effects. The results distinguished vegetation zones according to a general gradient of ecological limiting factors and show that + high‐resolution imagery are excellent tools for identifying the main vegetation groups within the lowland fan study site of dventdalen, but do not allow for detailed discrimination between species.
Dual influence of Atlantic and Pacific SST anomalies on the North Atlantic/Europe winter climate

Clustering analyses are used in both NCEP Reanalyses and model simulations to identify relationships between the low frequency variability of the zonal wind jet at 200hPa (U200) over the North Atlantic‐Europe domain and the geographical distribution of the Sea Surface Temperature (SST) anomalies. For winter months over the 1959‐1998 period, the U200 signature of the two phases of the North Atlantic Oscillation (NAO) is captured from NCEP in a cluster pair associated with the North Atlantic SST tripole. The classification also extracts a “La Niña” mode related to a strong ridge off Europe and reduced jet over the Azores. Model results confirm this dual oceanic association while exaggerating the ENSO influence. The role of the Atlantic SSTs is confirmed in model experiments where climatological SSTs are prescribed in the other basins. Tropical anomalies dominate the Atlantic SST signals and are linked to fluctuations of the jet consistently with the NAO phase.
A Three-Item Instrument for Measuring Daytime Sleepiness: The Observation and Interview Based Diurnal Sleepiness Inventory (ODSI).

STUDY OBJECTIVES We aimed to develop a new three-item assessment tool for daytime sleepiness in older adults, the Observation and interview-based Diurnal Sleepiness Inventory (ODSI) and determine its validity, internal consistency, test-retest reliability, and optimal cutoff score. METHODS A total of 133 elderly subjects including 73 patients with obstructive sleep apnea (OSA) (mean age, 79 y) and 60 controls (mean age, 80 y) were consecutively enrolled and answered all questionnaires. The ODSI questionnaire was validated using the Epworth Sleepiness Scale considered as a gold standard. Reliability, validity, and cut-points were tested. RESULTS The ODSI has acceptable validity, internal consistency, and test-retest reliability properties. The ODSI has internal consistency and a reliability coefficient (Pearson rho) of 0.70 for its three items, which suggests strong reliability. The estimated sensitivity and specificity were 0.842 with 95% confidence interval [0.624; 0.945] and 0.851 [0.761; 0.911], respectively. The consistency of summated scale scores during test and retest sessions was high (r = 0.970, 95% bootstrap confidence interval [0.898; 0.991]). Receiver operating characteristic analysis suggests that a cut-point of 6 is effective for identifying older adults with excessive levels of daytime sleepiness. CONCLUSIONS The ODSI is a brief, valid, easy-to-administer three-item assessment that can screen for excessive daytime sleepiness among elderly patients with OSA.
On the use of long‐term global data of land reflectances and vegetation indices derived from the advanced very high resolution radiometer

The availability of advanced very high resolution radiometer (AVHRR) time series of global shortwave data for the past two decades motivated many scientists to investigate interannual variability and trends in land surface conditions. For these studies the observed change in radiances due to two varying factors, namely, sensor responsivity and illumination conditions, must be known a priori because of the degradation of AVHRR shortwave channels and the orbit drift of afternoon spacecraft. The current work analyzes the behavior of global land AVHRR shortwave time series data for the last 12 years, processed using postlaunch calibration, and investigates their usefulness for the monitoring of global land surface processes. Its focus is on verifying the postlaunch calibrations for the AVHRR sensors on board NOAA 11 and 14. It is assumed that the NOAA 9 AVHRR calibration is correct so that the changing illumination effects can be parameterized based on its data. After accounting for the illumination effects, the residual trends in data, averaged over global deserts and rain forests, are attributed to calibration discrepancies. In particular, NOAA 11 calibration was found to yield only small residuals, whereas NOAA 14 calibration produced significant unrealistic global increase in both reflectances and vegetation indices. The artificial trends caused by the combination of calibration residuals and satellite-orbit drift should be removed to alleviate their misidentification as real trends in Earth's climate system and to make statistical studies of anomalies more reliable. This study draws attention to the above aspects of time series analysis with the available global AVHRR data and suggests ways to improve these data for interannual variability studies.
Wind-Driven Coastal Sea Level Variability in the Northeast Pacific

AbstractThe rate of coastal sea level change in the northeast Pacific (NEP) has decreased in recent decades. The relative contributions to the decreased rate from remote equatorial wind stress, local longshore wind stress, and local windstress curl are examined. Regressions of sea level onto wind stress time series and comparisons between NEP and Fremantle sea levels suggest that the decreased rate in the NEP is primarily due to oceanic adjustment to strengthened trade winds along the equatorial and coastal waveguides. When taking care to account for correlations between the various wind stress time series, the roles of longshore wind stress and local windstress curl are found to be of minor importance in comparison to equatorial forcing. The predictability of decadal sea level change rates along the NEP coastline is therefore largely determined by tropical variability. In addition, the importance of accounting for regional, wind-driven sea level variations when attempting to calculate accelerations in th.