Miracle-dz/UniFAR-FTUs huggingface dataset:
Seasonal variations of magnesium atoms in the mesosphere‐thermosphere

UV radiances from the Global Ozone Monitoring Experiment (GOME) spectrometer on the ERS‐2 satellite are used to determine long‐term dayside temporal variations of the total vertical column density below 795 km of the meteoric metal species Mg and Mg+ in the upper atmosphere. The GOME instrument has the ability to observe the ground state transition lines of Mg I at 285.2 nm and resolve the Mg II at 280 nm. A retrieval algorithm has been developed to determine column densities and applied to the years 1996–1997. Results show the middle latitude dayside Mg+ peaks in total vertical content during the summer, while neutral Mg demonstrates a much more subtle maximum in summer. Dayside trends are opposite previous midlatitude nighttime lidar observations, with the exception of calcium. The Mg+/Mg ratio has a seasonal variation, reaching a maximum in the summer. The total content of Mg+ is twice that of neutral Mg.
Criterion Functions for Document Clustering ∗ Experiments and Analysis

In recent years, we have witnessed a tremendous growth in the volume of text documents available on the Internet, digital libraries, news sources, and company-wide intranets. This has led to an increased interest in developing methods that can help users to effectively navigate, summarize, and organize this information with the ultimate goal of helping them to find what they are looking for. Fast and high-quality document clustering algorithms play an important role towards this goal as they have been shown to provide both an intuitive navigation/browsing mechanism by organizing large amounts of information into a small number of meaningful clusters as well as to greatly improve the retrieval performance either via cluster-driven dimensionality reduction, term-weighting, or query expansion. This ever-increasing importance of document clustering and the expanded range of its applications led to the development of a number of new and novel algorithms with different complexity-quality trade-offs. Among them, a class of clustering algorithms that have relatively low computational requirements are those that treat the clustering problem as an optimization process which seeks to maximize or minimize a particular clustering criterion function defined over the entire clustering solution. The focus of this paper is to evaluate the performance of different criterion functions for the problem of clustering documents. Our study involves a total of seven different criterion functions, three of which are introduced in this paper and four that have been proposed in the past. Our evaluation consists of both a comprehensive experimental evaluation involving fifteen different datasets, as well as an analysis of the characteristics of the various criterion functions and their effect on the clusters they produce. Our experimental results show that there are a set of criterion functions that consistently outperform the rest, and that some of the newly proposed criterion functions lead to the best overall results. Our theoretical analysis of the criterion function shows that their relative performance depends on (i) the degree to which they can correctly operate when the clusters are of different tightness, and (ii) the degree to which they can lead to reasonably balanced clusters.
Volatility of elemental carbon

A volatility technique whereby aerosol particles are heated to the relatively high temperature of 860 °C is used to infer the presence of elemental carbon in polluted air masses in the vicinity of the west coast of Ireland. The volume of elemental carbon for submicrometre sized particles contained in the aerosol is estimated from the fall off in number concentration at a critical onset temperature of about 730–735 °C, as also obtained for laboratory carbon ink aerosol. The technique permits determination of the elemental carbon volume percentage of the total fine aerosol volume, and an estimation of the abundance of elemental carbon contained within the black carbon fraction of the atmospheric aerosol. Supplementary black carbon mass concentration measurements were obtained using a thermal method and an aethalometer absorption method. The work suggests that elemental carbon can be identified using the volatility technique and that it can yield size-segregated information on the fraction of elemental carbon in atmospheric aerosol.
Geoarchaeological results from the harbor of Taposiris and implications concerning the construction of the harbor

The harbor of Taposiris was once a gateway to Egypt during the Roman period, and possibly even as early as the Hellenistic period. Built on the northern shore of Lake Mariout, the probable harbor was separated from the lake by a long artificial levee. A channel provided a link between the lake and the closed area that would have encircled the harbor basin. Our geoarchaeological study revealed a brackish environment influenced by the phreatic level and the Canopic branch that provided fresh water. The generally silty sediments proved to be difficult to analyze and contained few elements for discrimination between natural lake deposits and man-altered harbor deposits. A numerical model of circulation of water masses has been used to discern the spatial distribution of currents and the most active zonation for sediment re-suspension. This model emphasizes the fact that only very fine particles could reach and be deposited in the area of Taposiris. Our study illustrates the fact that the most striking element of the harbor (the EW levee) was entirely man-made and did not take advantage of any apparent natural feature. The bottom of the lake was more or less flat and devoid of any preexisting underwater ridge that could have facilitated the construction of the levee.
Statistical analysis of geosynchronous magnetic field perturbations near midnight during sudden commencements

When an interplanetary (IP) shock passes over the Earth's magnetosphere, the geosynchronous magnetic field strength near noon is always enhanced except for the magnetopause crossing events. Near midnight, however, it increases or decreases. This indicates that the nightside magnetosphere is not always compressed by a sudden increase in the solar wind dynamic pressure. To understand midnight geosynchronous magnetic field responses to IP shocks, we statistically examined geosynchronous magnetic field perturbations, corresponding to 120 sudden commencements (SCs), observed when geosynchronous spacecraft were near midnight between 2200 and 0200 magnetic local times. Out of the 120 SCs, 107 SCs were identified by one geosynchronous spacecraft, and 13 SCs were identified by two geosynchronous spacecraft. Thus, 133 events were used in our statistical study. We observed 23 events in spring, 40 events in summer, 32 events in fall, and 38 events in winter, respectively. A statistical study of the midnight geosynchronous SC perturbations reveals the following characteristics. (1) In summer, all events show a positive enhancement (+ΔBT) in the magnetic field strength. (2) In winter, however, ΔBT exhibits a positive (+ΔBT) or negative (–ΔBT) enhancement. (3) In summer, the midnight geosynchronous SC perturbations in the BH component (positive northward) in VDH coordinates are mostly (∼88%, 35 out of 40 events) positive (+ΔBH), while the occurrence rate of the positive perturbation (∼43%) in the Bz component (positive northward) in GSM coordinates is lower than that of the negative perturbation (∼57%). (4) In winter, the negative perturbations in ΔBH (∼61%) and ΔBz (∼74%) are dominant. (5) Both the north‐south components (BH and Bz) in spring and fall are scattered around zero. To explain the observations, we suggest that SC‐associated cross‐tail current (JSC) has a peak intensity around geosynchronous orbit and thus is a main controlling factor of midnight geosynchronous magnetic field perturbations during SCs. Specifically, we suggest that the seasonal variation of the sign of ΔBH, ΔBz, and ΔBT is due to the seasonal variation of the spacecraft position relative to JSC.
CLIMATE, ENVIRONMENTAL CHANGE, AND RESOURCES OF THE AFRICAN MOUNTAINS FROM THE MEDITERRANEAN TO THE EQUATOR

During the last 20,000 years, the mountains of Africa between the Mediterranean and the equator have experienced significant climatic changes with important consequences for the vegetation and resource potential. At about 18,000 B. P. present altitudinal belts were depressed and the zonation of climate and vegetation was changed considerably. In the Holocene, higher temperatures led not only to more humid conditions but also to an uplifting of altitudinal belts and transformation of climatic and ecological zones and to increased natural resource potential. These changes in climate, vegetation, and altitudinal zonation are illustrated in a series of schematic diagrams. The cumulative effects of natural and anthropogenic processes and impacts within the last 2,000 years are also depicted. In particular, human impact on ecosystems formed under more favorable climatic conditions could result in irreversible degradation. The mountains of the subtropics and tropics very often have more advantageous ecological conditions than the surrounding lowlands. They are an important resource potential for the future, although they may be very sensitive to climatic and anthropogenic changes.
New Nodosaurid Dinosaur from the Late Cretaceous of Lishui, Zhejiang Province, China

Abstract: A new genus and species of nodosaurid dinosaur: Zhejiangosaurus lishuiensis gen. et sp. nov. is erected herein. It is characterized by the sacrum consisting of at least three true sacral vertebrae, 5 caudal dorsal vertebrae fused to form the presacral rod, wide divergence of long slender preacetabular process of the ilium from the middle line of the body, and the fourth trochanter located at the femoral mid‐length.
Discontinuous change in temperature derivative of Vp in lower crustal rocks

Compressional wave velocities (Vp) of gabbronorite, pyroxene granulite, wehrlite and websterite were measured up to 1000°C at 1 GPa during heating and cooling. The wehrlite and websterite, which contain secondary hydrous minerals, show irreversible change in temperature derivative of Vp (∂Vp/∂T). During heating, these rocks show sudden decrease in Vp when dehydration reactions took place. During cooling, the rocks show a linear increase in Vp. In contrast, the gabbronorite and pyroxene granulite, which are nearly dry crystalline assemblage, show reversible and discontinuous change in ∂Vp/∂T at around 400°C. It changes from −2.4 and −2.1 × 10−4 km s−1 °C−1 to −4.7 and −4.5 × 10−4 km s−1 °C−1. This reversible and discontinuous change in ∂Vp/∂T is difficult to explain by the previously proposed mechanisms, such as thermal cracking, dehydration reaction, and/or partial melting. The data suggest that this reversible and discontinuous change would be associated with phase transition in plagioclase.
An Ordovician vertebrate from western New South Wales, with comments on Cambro-Ordovician vertebrate distribution patterns

Young, G.C. , March, 2009. An Ordovician vertebrate from western New South Wales, with comments on Cambro-Ordovician vertebrate distribution patterns. Alcheringa 33, 79–89. ISSN 0311-5518. A fish plate impression from the Ordovician Rowena Formation in Mutawintji National Park is referred to an indeterminate species of the genus Arandaspis Ritchie & Gilbert-Tomlinson, 1977, genotype of the family Arandaspididae, previously known only from the Middle Ordovician Stairway Sandstone in the Amadeus Basin of central Australia. The Rowena Formation has previously been correlated with units underlying the Stairway Sandstone (Pacoota Sandstone, Horn Valley Siltstone) in the Amadeus Basin, from which a second arandaspid Porophoraspis represents the earliest occurrence in the fossil record that demonstrates two defining developmental characters of the vertebrates (neural crest, epidermal placodes). The new occurrence of Arandaspis is consistent with the Middle Ordovician (Darriwilian) age for the upper part of the Rowena Formation indicated by recent studies of trilobites. The order Arandaspidiformes, also known from the Upper Ordovician of South America (Sacabambaspis), defines a ‘Gondwana Endemic Assemblage’, which may have been established already by the late Cambrian. Although the first phase of vertebrate biomineralization is not yet documented from the Cambro-Ordovician of Asia, the oldest vertebrates in the early Cambrian Chengjiang fauna and diverse agnathans and gnathostomes by Early Silurian time in South China implicate this as a significant area in the evolution of the earliest vertebrates.
Radium 226 measurements from the 1969 North Pacific Geosecs Station

The profile of 226Ra with depth at the 1969 Geosecs calibration station in the Pacific Ocean was determined by four different groups of investigators. The Lamont-Doherty group led by Broecker (LDGO-B) used the shipboard in situ method, the University of Southern California group (USC) and the Scripps Institution of Oceanography group (SIO) used the laboratory regenerated radon method, and the Lamont-Doherty group led by Kaufman (LDGO-K) used an isotope dilution method. Most measurements agree to within 15%.
Slab melting as an explanation of Quaternary volcanism and aseismicity in southwest Japan

Two volcanoes on the Quaternary volcanic front in southwest Japan have erupted medium-K andesite and dacite, which are chemically similar to adakites (i.e., high Al 2 O 3 , Sr/Y, low Y, and steep rare earth element [REE] patterns with no negative Eu anomalies), unlike other subduction-related volcanoes in Japan. Earthquake data and the extrapolated position of the Philippine Sea plate from its near-trench position indicate that the leading edge of the plate is ∼75–100 km deep beneath these volcanoes. Melting of the plate at this depth would leave a garnet eclogite residual, accounting for the Y and heavy REE depletion. The lack of seismic data and active volcanism in southwest Japan can be attributed to the attenuated seismic response of the plate due to melting and to the atypical nature of magma generation.
Fragmented Indian plate and vertically coherent deformation beneath eastern Tibet

[1] Using fundamental mode Rayleigh waves from the INDEPTH-IV and Namche-Barwa seismic experiments for periods between 20 and 143 s, we have investigated the lithospheric structure beneath eastern Tibet. We have found a ∼200-km-wide high velocity body, starting at ∼60 km depth and roughly centered beneath the Bangong-Nijuang Suture, which is most likely a piece of the underthrusting Indian continental lithosphere. The sub-horizontal underthrusting of the Indian lithosphere beneath eastern Tibet appears to be accompanied by its lateral tearing into at least two fragments, and subsequent break-off of the westernmost portion at ∼91°E-33°N. The uppermost mantle low velocity zone we observe beneath the N. Qiangtang and Songpan-Ganzi terranes is most probably due to warmer and thinner lithosphere relative to southern Tibet. We attribute the low velocity zones concentrated along the northern and southern branches of the eastern Kunlun fault at lithospheric depths to strain heating caused by shearing. The azimuthal fast directions at all periods up to 143 s (∼200 km peak sensitivity depth) beneath the N. Qiangtang and Songpan-Ganzi terranes are consistent, suggesting vertically coherent deformation between crust and uppermost mantle. Furthermore, the low velocity zone below the Kunlun Shan reaching down to >200 km argues against a present southward continental subduction along the southern margin of Qaidam Basin.
Heavy Metals and Organic Pollutants in Sediments of Dar es Salaam Harbour Prior to Dredging in 1999.

Heavy metals and organic contaminants were analysed in the sediments of the inner area of the Dar es Salaam harbour. Complementary analytical parameters, such as, the organic carbon content and the silt/clay fraction of the sediments showed good positive correlation (r = 0.64). Stations that had high content of fine grain material in the sediment also indicated relatively high level of organic carbon and pollutants. The Florida criteria (MacDonald 1993) for assessment of pollution of tropical marine sediments was adopted in oredr to evaluate the extent of pollution in Dar es Salaam harbour sediments. The Florida criteria is one of the established references for sediment quality assessment. Heavy metals that had concentrations above the Florida no effect level were chromium, copper, lead, mercury and zinc. Mercury exceeded the Florida no effect level (0.1 mgkg-1) at 18 of 22 sampling stations, but the Florida probable effect level (1.4 mgkg-1) was not closely reached at any station. Lead and chromium exceeded the Florida no effect level (21 mgkg-1and 33 mgkg-1respectively) at 15 stations. Copper and zinc exceeded the Florida no effect level (28 mgkg-1and 68 mgkg-1respectively) at 12 and 16 stations respectively. Levels of pollutants in the study area were generally lower than in the sediments of some major harbours of the world. Tanzania Journal of Science Volume 26 (2000), pp. 29-46
Petrogenetic and tectonic significance of Permian calc-alkaline lamprophyres, East Kunlun orogenic belt, Northern Qinghai-Tibet Plateau

We present new geochronological, mineralogical, geochemical, and isotopic data for recently recognized lamprophyre dikes in the East Kunlun orogenic belt of NW China. Based on euhedral amphibole phenocrysts and fine-grained, plagioclase-bearing groundmass with accessory magnetite, apatite, and titanite, these dikes are classified as spessartites. Plagioclase in these rocks is Ca-rich with An ranging from 45 to 82. Most of the amphibole phenocrysts are magnesiohastingsite or ferropargasite, with systematic ‘‘normal’ zoning in which Al2O3, CaO, and Mg# decrease from core to rim. The dikes have moderate Mg# (43–49) and high Al2O3 (17.5–18.0 wt.%), FeOtotal (7.4–8.4 wt.%), and CaO (5.9–7.4 wt.%). Based on low total alkalis (Na2O + K2O = 4.2%–5.0 wt.%), most samples plot in the low-K, calc-alkaline field. They are enriched in large-ion lithophile elements (e.g. K, Rb, Sr, and Ba) and light rare-earth elements, but are depleted in high-field-strength elements (e.g. Ta, Nb, P, and Ti), and have enriched Sr-Nd-Hf isotopic compositions ((87Sr/86Sr)i = 0.70883–0.71045, εNd(t) = –5.51–5.72, εHf(t) = –4.42–0.38). Zircon U–Pb geochronology indicates that the dikes were emplaced at 253 ± 2.5 Ma and are unrelated to their granite host, which has an age of 443 ± 1.7 Ma. The geochemical and isotopic data suggest derivation from an enriched lithospheric mantle source that had been metasomatized by subduction-related fluids. Low degrees of partial melting of a phlogopite-bearing, spinel peridotite, followed by fractional crystallization of olivine, amphibole, and Ti-bearing minerals, can account for the observed geochemical features of the dikes. Trace element geochemistry and regional geology suggest that the East Kunlun lamprophryes formed in a subduction-related setting.
The Law of Parsimony in Gradient Descent for Learning Deep Linear Networks

Over the past few years, an extensively studied phenomenon in training deep networks is the implicit bias of gradient descent towards parsimonious solutions. In this work, we investigate this phenomenon by narrowing our focus to deep linear networks. Through our analysis, we reveal a surprising"law of parsimony"in the learning dynamics when the data possesses low-dimensional structures. Specifically, we show that the evolution of gradient descent starting from orthogonal initialization only affects a minimal portion of singular vector spaces across all weight matrices. In other words, the learning process happens only within a small invariant subspace of each weight matrix, despite the fact that all weight parameters are updated throughout training. This simplicity in learning dynamics could have significant implications for both efficient training and a better understanding of deep networks. First, the analysis enables us to considerably improve training efficiency by taking advantage of the low-dimensional structure in learning dynamics. We can construct smaller, equivalent deep linear networks without sacrificing the benefits associated with the wider counterparts. Second, it allows us to better understand deep representation learning by elucidating the linear progressive separation and concentration of representations from shallow to deep layers. We also conduct numerical experiments to support our theoretical results. The code for our experiments can be found at https://github.com/cjyaras/lawofparsimony.
Sensitivity tests of a two-layer hydrodynamic model in the Gulf of Finland with different atmospheric forcings

A two-dimensional, two-layer baroclinic prognostic hydrodynamic model has been developed and compared with measurements of surface salinity and temperature, the thickness of the upper mixed layer and water level height. The model’s ability to reproduce the main hydrographic features of the Gulf of Finland is tested. Special attention is paid to the role of atmospheric forcing. In the first simulation the atmospheric forcing derived from the observations of a single weather station (Kalbadagrund) was used. The results of this simulation were compared with the results of model runs, for which the atmospheric input was taken from the HIRLAM meteorological model. The accuracy of the results improved when the HIRLAM input was used. However, even the version of the HIRLAM model used, which had a horizontal resolution of 55*55 kilometres, could not accurately enough describe the complicated structure of the atmospheric wind and temperature fields over the narrow Gulf (width ca. 40-150 kilometres).
Summer‐winter hemisphere asymmetry of the preliminary reverse impulse of geomagnetic storm sudden commencements at midlatitudes

[1] We present event-specific observational evidence for the prevalence of a summer-winter hemisphere asymmetry of the preliminary reverse impulse (PRI) of geomagnetic storm sudden commencements (SSCs) at midlatitudes of the local afternoon sector. The evidence is culled from the archived 10-s resolution data of midlatitude stations (geomagnetic latitude 23–46°) of the MM 210 magnetometer network. The hemisphere asymmetry is characterized by a larger peak amplitude of PRI in the summer hemisphere than in the winter hemisphere, and this feature is more prominently seen in the December solstice compared to the June solstice. In the December solstice SSC event, the amplitude of the preliminary reverse impulse, PRI (4.8 nT) at BRV (geomagnetic latitude 36.6°S) in the summer hemisphere is larger by a factor of 6 compared to that at MSR (geomagnetic latitude 37.6°N) in the winter hemisphere. The asymmetry is also apparent at lower latitudes: while the PRI assumed an amplitude of 3.7 nT at LEM (geomagnetic latitude 34.1°S), it is barely discernible at ONW (geomagnetic latitude 31.6°N) in the winter hemisphere. In the June solstice event, the PRI amplitude at RIK (geomagnetic latitude 34.7°N) in the summer hemisphere is higher by a factor of 3.44 compared to that at LEM (geomagnetic latitude 34.1°S) in the winter hemisphere. A similar behavior is also apparent in the equinox event though the hemisphere asymmetry of the preliminary reverse impulse (PRI) here is of moderate strength. In all the SSC events studied, the main impulse (MI) amplitude also exhibited the well-known summer-winter asymmetry, but the hemisphere asymmetry is more prominent with the preliminary reverse impulse (PRI) than with the main impulse (MI). Physical processes that could possibly account for the hemisphere asymmetry evidenced of the afternoon PRI at midlatitudes are discussed.