nils-herrmann/clean_scirepeval huggingface dataset:
Inversion formulae for the spherical mean in odd dimensions and the Euler–Poisson–Darboux equation

The paper contains a simple proof of the Finch–Patch–Rakesh inversion formula for the spherical mean Radon transform in odd dimensions. Inversion of that transform is important for thermoacoustic tomography and represents a challenging mathematical problem. The argument relies on the idea of analytic continuation and known properties of the Erdelyi–Kober fractional integrals. The result is applied to the solution of the Cauchy problem for the Euler–Poisson–Darboux equation with initial data on the cylindrical surface.

Field of study: Mathematics
Where is the sky

This paper discusses the origin of the concept of sky. It is shown to emerge from one’s experience of the visual perception of nonluminous objects observed in/through the atmosphere during the daytime. The physical concept of visibility in the atmospheric environment underpins the perception of a flattened sky dome constructed by our mind. In addition, the Moon illusion receives a plausible explanation and both topics become appropriate for a conceptually oriented introduction course in physics and/or astronomy.

Field of study: Philosophy
Effects of Planetary Wave Propagation and Finite Depth on the Predictability of Atmospheres

Theoretical predictability of the atmosphere is limited in part by the rate at which small-scale observational errors in the initiation of a forecast grow both in amplitude and in length scale with increasing time. Processes of error growth are examined for the case of equivalent barotropic motion on a β-plane. From direct numerical simulations and from statistical closure theory, it is seen that larger β implies slower rate of error growth. Thus planetary wave propagation enhances predictability. Inclusion of a finite equivalent depth also enhances predictability. For values of β and of the equivalent depth representative of Earth's atmosphere, a theoretical predictability time scale is increased fourfold over earlier calculations based on uniformly rotating, “rigid lid” models.

Field of study: Physics
THE INVESTIGATION OF APPLICABILITY OF WORKSHEETS WAS DEVELOPED FOR PROJECTION UNIT IN SOLID GEOMETRY

Solid Geometry is one of the topics that students have difficulties in Geometry. In this study, worksheets about projections were developed and it was investigated the applicability of the worksheets in real class environment. Worksheets were applied in a secondary school 12th grade class which consisted of 36 students in Trabzon. Results of the study show those worksheets which required using three-dimensional dynamic geometry software such as Cabri 3D facilitate to learn the topics of Space Geometry and using dynamic geometry software in geometry class made students pleasant. Another important result is that these kinds of worksheets enhance students' interests to the lesson. Based on this study, that kind of worksheets which required using dynamic geometry software should be developed for other topics in Space Geometry.

Field of study: Education
New Results in Sridhar Filtering Theory

A nonlinear adaptive filter is introduced and applied to the classical problem of detecting a sinusoidal signal, with unknown frequency, in white noise. The filter is basically a new result in what is known as Sridhar filtering theory. In the derivation of the filter, called the “Pontryagin filter”, the Pontryagin minimum principle and the method of invariant imbedding are used. The stability, bias and convergence properties are also studied and presented.

Field of study: Mathematics
3D‐Var Hessian singular vectors and their potential use in the ECMWF ensemble prediction system

Singular vectors are computed which are consistent with 3D-Var (three-dimensional variational) estimates of analysis error statistics. This is achieved by defining the norm at initial time in terms of the full Hessian of the 3D-Var cost function. At final time the total energy norm is used. the properties of these Hessian singular vectors (HSVs) differ considerably from total energy singular vectors (TESVs) in such aspects as energy spectrum and growth rate. Despite these differences, the leading 25 TESVs and HSVs explain nearly the same part of the 2-day forecast error. 
 
Two experimental ensemble configurations are studied. One configuration uses perturbations based on HSVs in the computation of initial perturbation, the other uses TESVs and 2-day linearly evolved singular vectors (ESVs) of two days before. the latter approach provides a way to include more stable and large-scale structures in the perturbations. Ten pairs of ensembles are compared to the operational European Centre for Medium-Range Weather Forecasts Ensemble Prediction System. the ensembles using ESVs perform slightly better. the ensembles based on HSVs show a slightly worse performance and are lacking some spread in the medium range. Possible directions to improve the computation of HSVs are discussed.

Field of study: Mathematics
Is Yablo's paradox Liar-like?

The most obvious difference between Yablo's paradox and traditional versions of the Liar is that Yablo's paradox is generated by considering an infinite collection of sentences (So, S1, and for each n, Sn). If we restrict ourselves to a finite collection of the Sn, then no paradox arises. The upshot of this is that there is no first-order derivation of a contradiction from Yablo's premisses and the Tarski biconditionals. The second difference is that Yablo's paradox requires an infinite number of instances of the T-schema. With traditional versions of the Liar we only need to appeal to a finite number of instances of the T-schema. Yablo's paradox will not go through if we limit ourselves to only a finite number of such instances. Suppose otherwise, then there is a proof of a contradiction from the Yablo sentences and some finite subset of the Tbiconditionals for the Yablo sentences. Call this proof P.2 Since P mentions only a finite number of the T-biconditionals, there is a greatest number m such that P mentions the T-biconditional for Sm. Now consider a model in which for all n> m, the T-biconditional for Sn does not hold. (Note that in

Field of study: Mathematics
Production of particles containing charmed quarks in hadronic collisions

The ability to obtain the correct cross section for production of the new 3.1-GeV resonance at Brookhaven National Laboratory using the natural analog of the Drell-Yan annihilation mechanism leads us to explore further implications of this approach. We present in detail the longitudinal- and transverse-momentum dependence of the cross section, as well as its dependence upon beam energy. We point out correlations among final-state multiplicity, longitudinal momentum of the resonance, and resonance mass peculiar to the parton-model annihilation mechanism. We also examine the alterations which are expected upon employing an anti p beam. Finally, we obtain cross sections for charmed meson and baryon production. D$sup 0$* and D$sup -$* mesons should have particularly large production cross sections.

Field of study: Chemistry
Numerical simulation on a kind of linear phase retrieval wavefront measuring method

The characteristics of a new kind of linear phase retrieval(LPR) wavefront measuring method were analyzed.The process of calibration was discussed and the basic construct of the LPR was described.The influences of the system aberration,the characteristic of reconstruction matrix, and the coefficient of mode calibration on the performance of the LPR method were tested by numerical simulation.According to the calculation of the condition number of reconstruction matrix,the relationship between the target size and performance of LPR was discussed.The simulative results show that this method is feasible.

Field of study: Mathematics
New Method for Infrared Small Target Detection under Complex Background

A new method based on the wavelet packet transform and skewness was proposed for infrared small target detection under complex background.The wavelet packets were applied to decompose the image into pyramid subbands at different scales and solve the problem of the higher frequencies having lower resolutions.Then a Gaussian measurement criterion based on skewness was proposed to test the Gaussian nature of the wavelet packet coefficients and finally the exact detection result was obtained.The experiments were performed for some real IR images, and the results prove that the proposed method is effective for small IR target detection.

Field of study: Mathematics
New algorithm for binary connected component labeling

Binary connected component detection and labeling is an essential step in many image analysis techniques,highly efficient connected component labeling algorithm can greatly speed up image processing.Aiming at this point,a new algorithm based on run-length encoding is presented.It scans the image,records all the run-length codes and appends the equivalent pairs to the equivalent linked list.It analyzes the equivalent linked list by recursive method,obtains the mapping between old labels and the new ones and corrects the old labels obtained.The comparative experiments with several traditional algorithms and two improved methods show that it is more effective.

Field of study: Computer science
Analysis of loss of residual heat removal system during mid-loop operation of a 300 MWe PWR

Thermal-hydraulic response of a two-loop pressurized water reactor is studied on loss of residual heat removal system (RHRS) during mid-loop operation. Decay heat during mid-loop operation is removed by RHRS. On loss of RHRS, no cooling system is available to cool the core. Transient thermal-hydraulic analysis of the plant is performed using RELAP/SCDAP on loss of RHRS. For this purpose, first steady-state is achieved at mid-loop conditions. System obtains steady-state at primary coolant inventory of 58000 kg, water level of 7.8m in the reactor pressure vessel (RPV) and upper plenum pressure of 104.41 kPa. On loss of RHRS, the core uncovery time, maximum reactor system pressure and cladding temperature are determined under four accidental scenarios in absence of any mitigation measure. The results show that the core uncovery time for the open case of reactor pressure vessel top vent valve (RPV top vent valve), pressurizer relief valve (PZR valve), steam generator man way and pressurizer man way are 423.1, 214.4, 50.1, 67.2 min respectively. The effect of reflux condensation for the above accidental configurations has also been studied. It is found that reflux condensation is a prominent phenomenon to increases core uncovery time for open case of RPV top vent valve and PZR valve.

Field of study: Engineering
VampireVerb: A surreal simulation of the acoustics of Dracula’s Castle

This work introduces VampireVerb, a parameterized modal reverberator created from acoustics measurements recorded at Bran Castle in Transylvania, Romania, popularly called “Dracula's Castle.” With limited evening access to the space, balloon pop sources were recorded using an A-format microphone and handheld recorder in several acoustically interesting rooms, including the armory. Spatial impulse responses were estimated from the balloon pop recordings, and a modal reverberator was designed to simulate the measured acoustics. In the main rooms, reverberation times T30 in the range [0.7 s, 1.2 s] were noted. A long, narrow stairwell and the torture chamber were acoustically dry, and did not produce the sound one would typically associate with Dracula's Castle. To bridge this gap between the actual and imagined acoustics, the mode frequencies and dampings were parametrized so as to interactively vary the size of the space and materials present, transforming the recorded rooms into large, stone spaces with t...

Field of study: Computer science
Trou sans Fond submarine canyon: Ivory Coast, Africa

A bathymetric chart of the Trou sans Fond (Bottomless Hole) submarine canyon off the Ivory Coast, Africa, is presented, based upon a 1400-km survey in 1968 by the O.S.S. Discoverer. The canyon originates with a double head just off the beach and cuts a deep V-shaped furrow across the 30-km-wide shelf, attaining a maximum relief of 450 fm (823 m) near the shelf break. The canyon has a slightly sinuous and rugged relief down the continental slope, indicating an active erosional regime. At 1500 fm (2745 m) where the continental rise commences, the canyon is abruptly offset 20 km to the west, suggesting that the present outer fan valley is a newly developed channel. On the continental rise a depositional regime is indicated by well developed natural levees which have a cross-sectional area 60 times that of the Mississippi in the delta region. The Trou sans Fond appears to be the only canyon which taps the paralic zone between the Cayar Canyon to the north and the Congo Canyon to the south.

Field of study: Geography
Isotopic analysis of equid teeth from Wonderwerk Cave, northern Cape Province, South Africa

Stable carbon and nitrogen isotope ratios have been determined from equid teeth from a well-dated sequence of Holocene deposits at Wonderwerk Cave, situated in a summer-rainfall area of the northern Cape Province of South Africa. Stable carbon isotope ratios confirm the existence of a C 4 grassland habitat throughout the Holocene. Nitrogen isotope ratios are assessed in relation to data from modern equid samples from southern Africa. Temporal variability in both carbon and nitrogen isotope ratios of Holocene equid samples from Wonderwerk appears to be analogous to spatial variability of such ratios determined for faunal samples from modern environments. Relationships between isotope ratios and data from modern environments are used to obtain rainfall indices.

Field of study: Geology
Geochemistry of late Middle Jurassic–Early Cretaceous igneous rocks on the eastern North American margin

Geochemical analyses have been made of late Middle Jurassic to Early Cretaceous volcanic rocks on the eastern North American margin from Baltimore Canyon northeastward to the Newfoundland Seamounts. Samples from the Newfoundland Seamounts were obtained from dredge hauls, from the New England Seamounts from Deep Sea Drilling Project holes, and from the Grand Banks, Scotian Shelf, Georges Bank, and Baltimore Canyon area from exploratory oil wells. All of the rocks analyzed are alkali basalts and related mafic rocks. The analytical data allow the rocks to be divided into two distinct igneous suites. The New England suite includes the Baltimore Canyon, Georges Bank, and New England Seamounts. Rocks from these areas show marked enrichment in light REE and many incompatible trace elements. The Eastern Canadian suite, consisting of rocks from the Scotian Shelf and Grand Banks, show slightly convex REE spectra and less enrichment in incompatible elements. The rocks from the New England suite contain high-pressure clinopyroxene phenocrysts, some of which show complex zoning; these are absent in rocks from the Eastern Canadian suite. The data available from these offshore areas is limited and does not permit a unique petrogenetic explanation for the geochemical differences between the two suites. The Eastern Canadian suite resembles early-formed alkali rocks from Loihi Seamount, interpreted as the products of a low degree of partial melting of a MORB-type mantle source. This source was slightly depleted in LREE in order to produce the observed convex LREE spectra. The New England suite closely resembles many ocean island basalt suites. Our data do not allow discrimination between various current hypotheses for the origin of relative enrichment in incompatible elements of alkali olivine basalts. Variations in element ratios for geochemically very similar element pairs (such as La/Ce and Zr/Hf) suggest that the mantle beneath the two suites may have different compositions. The mantle composition inferred for the New England suite is similar to that postulated by many authors as resulting from mantle plumes. The localization of the volcanism in the Early Cretaceous, however, is related to the development of fractures, some of which resulted from reactivation of old fracture zones.

Field of study: Chemistry, Geology
Sensitivity of Pliocene Ice Sheets to Orbital Forcing

The stability of the Earth's major ice sheets is a critical uncertainty in predictions of future climate and sea level change. One method of investigating the behaviour of the Greenland and the Antarctic ice sheets in a warmer-than-modern climate is to look back at past warm periods of Earth history, for example the Pliocene. This paper presents climate and ice sheet modelling results for the mid-Pliocene warm period (mPWP; 3.3 to 3.0 million years ago), which has been identified as a key interval for understanding warmer-than-modern climates (Jansen et al., 2007). Using boundary conditions supplied by the United States Geological Survey PRISM Group (Pliocene Research, Interpretation and Synoptic Mapping), the Hadley Centre coupled ocean–atmosphere climate model (HadCM3) and the British Antarctic Survey Ice Sheet Model (BASISM), we show large reductions in the Greenland and East Antarctic Ice Sheets (GrIS and EAIS) compared to modern in standard mPWP experiments. We also present the first results illustrating the variability of the ice sheets due to realistic orbital forcing during the mid-Pliocene. While GrIS volumes are lower than modern under even the most extreme (cold) mid-Pliocene orbit (losing at least 35% of its ice mass), the EAIS can both grow and shrink, losing up to 20% or gaining up to 10% of its present-day volume. The changes in ice sheet volume incurred by altering orbital forcing alone means that global sea level can vary by more than 25 m during the mid-Pliocene. However, we have also shown that the response of the ice sheets to mPWP orbital hemispheric forcing can be in anti-phase, whereby the greatest reductions in EAIS volume are concurrent with the smallest reductions of the GrIS. If this anti-phase relationship is in operation throughout the mPWP, then the total eustatic sea level response would be dampened compared to the ice sheet fluctuations that are theoretically possible. This suggests that maximum eustatic sea level rise does not correspond to orbital maxima, but occurs at times where the anti-phasing of Northern and Southern Hemisphere ice sheet retreat is minimised.

Field of study: Geology
Co-existing cordierite-almandine-a key to the metamorphic history of Sri Lanka

A co-existing cordierite—almandine assemblage is described from the pelitic metasedimentary rocks of the Precambrian granulite-facies terrain of Sri Lanka. The chemical control on this assemblage is demonstrated, as has been observed in granulite-facies terrains elsewhere. The previous view of a low-pressure origin of cordierite in pelitic rocks, and the subdivision of the central granulite-facies belt of Sri Lanka based thereon, is hence doubtful.

Field of study: Geology
Radiation patterns: Possibility for monitoring seismic sources

Recent field measurements of the radiation in boreholes indicate that the radiation patterns of real seismic sources are not always in agreement with those corresponding to the point‐source excitation in unbounded homogeneous and isotropic acoustic or elastic media [we refer the reader to Aki and Richards (1980) for the basic discussion on the radiation patterns in homogeneous media]. This mismatch results from the fact that the point‐source radiation patterns corresponding to homogeneous media are too simplistic to satisfy any experiment in the more realistic Earth environment. A study of radiation patterns is certainly important not only to predict possible seismic events but also to analyze the source performance itself by recording seismic arrivals.

Field of study: Geology
Sapphirine bearing granulites from the Sipiwesk Lake area of the late Archean Pikwitonei granulite terrain, Manitoba, Canada

Sapphirine occurs in the orthopyroxene-cordierite and feldspar-sillimanite granulites in the Sipiwesk Lake area of the Pikwitonei granulite terrain, Manitoba (97°40′W, 55°05′N). The orthopyroxene-cordierite granulites have extremely high Al2O3 (24.5 wt%) and MgO (24.6 wt%) contents and contain sapphirine (up to 69.2 wt% Al2O3), aluminous orthopyroxene (up to 8.93 wt% Al2O3), cordierite, spinel, phlogopite, and corundum. Sapphirine forms coronas mantling spinel and corundum. Corona sapphirine is zoned and its composition varies through the substitution (Mg, Fe, Mn) Si=2 Al as a function of the phases with which it is in contact. Textural and chemical relationships of sapphirine with coexisting phases indicate that spinel + cordierite reacted to form orthopyroxene + sapphirine under conditions of increasing pressure. Moreover, decreasing core to rim variation of Al2O3 in orthopyroxene porphyroblasts suggests decreasing temperature during sapphirine formation. On the basis of experimentally determined P-T stability of the assemblage enstatite + sapphirine + cordierite, and the Al content of hypothetical Fe2+-free orthopyroxene associated with sapphirine and cordierite, metamorphic temperatures and pressures are estimated to be 860–890° C and 3.0–11.2 kbar.In the feldspar-sillimanite granulites, sapphirine occurs as a relict phase mantled by sillimanite and/or by successive coronas of sillimanite and garnet. These textural relations suggest the reaction sapphirine + garnet + quartz = orthopyroxene + sillimanite with decreasing temperature. Compositions of minerals in the assemblage garnet-orthopyroxene-sillimanite-plagioclase-quartz, indicate metamorphic P-T conditions of 780–880° C and 9±1 kb.The metamorphic conditions estimated in this study suggest that the sapphirine bearing granulites in the Sipiwesk Lake area represent Archean lower crustal rocks. Their formation might be related to the crustal thickening processes in this area as suggested by Hubregtse (1980) and Weber (1983).

Field of study: Geology