bluuebunny/crossref_metadata_2025_split huggingface dataset:
Global equivalent slab thickness model of the Earth’s ionosphere
Authors: Jakowski Norbert , Hoque Mohammed Mainul 
Published: January 2021

The shape of the vertical electron density profile is a result of production, loss and transportation of plasma in the Earth’s ionosphere. Therefore, the equivalent slab thickness of the ionosphere that characterizes the width of vertical electron density profiles is an important parameter for a better understanding of ionospheric processes under regular as well as under perturbed conditions. The equivalent slab thickness is defined by the ratio of the vertical total electron content over the peak electron density and is therefore easy to compute by utilizing powerful data sources nowadays available thanks to ground and space based GNSS techniques. Here we use peak electron density data from three low earth orbiting (LEO) satellite missions, namely CHAMP, GRACE and FORMOSAT-3/COSMIC, as well as total electron content data obtained from numerous GNSS ground stations. For the first time, we present a global model of the equivalent slab thickness (Neustrelitz equivalent Slab Thickness Model – NSTM). The model approach is similar to a family of former model approaches successfully applied for total electron content (TEC), peak electron density NmF2 and corresponding height hmF2 at DLR. The model description focuses on an overall view of the behaviour of the equivalent slab thickness as a function of local time, season, geographic/geomagnetic location and solar activity on a global scale. In conclusion, the model agrees quite well with the overall observation data within a RMS range of 70 km. There is generally a good correlation with solar heat input that varies with local time, season and level of solar activity. However, under non-equilibrium conditions, plasma transport processes dominate the behaviour of the equivalent slab thickness. It is assumed that night-time plasmasphere–ionosphere coupling causes enhanced equivalent slab thickness values like the pre-sunrise enhancement. The overall fit provides consistent results with the mid-latitude bulge (MLB) of the equivalent slab thickness, described for the first time in this paper. Furthermore, the model recreates quite well ionospheric anomalies such as the Night-time Winter Anomaly (NWA) which is closely related to the Mid-latitude Summer Night-time Anomaly (MSNA) like the Weddell Sea Anomaly (WSA) and Okhotsk Sea Anomaly (OSA). Further model improvements can be achieved by using an extended model approach and considering the particular geomagnetic field structure.
Simulation and optimization of working parameters of the rapid-dissolution device of hydrophobically associating polymer
Authors: Wang Shikai , Shu Zheng , Ye Zhongbin , Zhu Shijie , Zhang Lei 
Published: January 2021

To solve the dissolution problem of hydrophobically associating polymers during the application process, a rapid-dissolution device was developed and optimized. The relevant parameters of the device were simulated with a focus on the fluid-passing capacity, rotating speed, and device structure to study the dissolution effect using the Fluent software. The results indicated that under the condition that the fluid-passing capacity of a single rapid-dissolution device was 12 m3/h, the viscosity of the hydrophobically associating polymer solution allowed to pass through the device should not exceed 21 mPa s. When the rotating speed of the rotor was 1440 rpm, the polymer had uniform distribution when passing through the device and could achieve a good tensile dissolution effect. By installing a fan blade in the device, the retention problem of polymer swelling particles in the dissolution device was solved, and the dispersion and dissolution of the polymer are promoted. The rapid-dissolution device was suitable for the dissolution of hydrophobically associating polymers in the oil field and so as to promote the application of hydrophobically associating polymers.
Enhancement for magnetic field strength of a magnetohydrodynamic thruster consisting of permanent magnets
Authors: Li Yan-Hom , Zeng Cing-Hui , Chen Yen-Ju 
Published: January 2021

This study designs a closed-loop magnetic circuit using permeable materials to increase the uniformity and intensity of the magnetic field based on an internal conductive square Magnetohydrodynamics (MHD) thruster that consists of a pair of NdFeB magnets. To reduce the magnetic leakage from the thruster, magnetic shields made of various permeable metals are used to encase the MHD thruster. The experimental results show that a stainless steel shell lighter than a black iron shield and moderately increases the magnetic field strength is more suitable for applications in seawater. For a single shield, the field intensity inside the thruster increases linearly with the thickness of the shell. The field strength increases further when a second shell is used. However, the field intensity decreases when the distance between the two shells is increased. An MHD thruster that is 100 mm long, 5mm wide, and 50mm high is hung on a sliding track with negligible friction and is fully submerged in the saline water for the verification of its performance. Increasing the thickness of the stainless steel shell from 2mm to 4mm results in the increase of the propulsive force from 0.064 N to 0.265 N, and the speed of the thruster from 0.075m/s to 0.098 m/s, respectively. The experimental results are used to propose a modified design for a magnetic circuit that increases the uniformity and strength of the magnetic field in the central region of a square MHD thruster that consists of permanent magnets.
Modern Physics and Space Science
Authors: Carpenter D. Rae , Minnix Richard B. 
Published: January 2021

Use battery–operated vehicle moving at constant speed. Place vehicle on butcher paper ∼1.5 m long so tractor moves transverse to longer dimension of paper. First, run tractor with paper stationary. Repeat, while pulling paper by hand at as constant speed as possible. Repeat with tractor moving in direction of paper motion and opposite to paper motion. Try moving paper at same speed as tractor but in opposite direction so tractor remains motionless in lab frame.
DISCUSS classic problem of rowing to point directly across a swiftly moving river. If appropriate, explain why a light source, moving at speed of light, does not result in “stopping” light beam.
Using linguistic atlases to explore syntactic issues
Authors: Massanell i Messalles Mar 
Published: January 2021

Abstract
Traditional linguistic atlases are not designed
to collect data about syntactic variation. Nonetheless, it is
possible to obtain from them information about particular syntactic
issues, as I exemplify with the Atles Lingüístic del Domini
Català. This atlas offers evidence of the survival of
the perfect auxiliary ésser ‘to be’ in some current
Catalan varieties in the face of general replacement by
haver ‘to have’. These examples are discussed
in the context of the changes that Catalan has undergone since the
Middle Ages. We see that the residual presence of
ésser varies from region to region and reflects
different processes. However, in order to be precise it will be
necessary to undertake a further data collection specifically
focused on auxiliary selection.
On the role of prosody in wh-in-situ
Authors: Duguine Maia , Irurtzun Aritz 
Published: January 2021

Abstract
A growing number of works propose a direct role
of PF in the generation of wh-in-situ. Relying
mainly on data from Basque, we critically evaluate two such
proposals (Richards,
2010; Mathieu,
2016) and argue that they face a range of empirical and
conceptual shortcomings. We contrast these with the more
“syntactocentric” proposal of Cheng & Rooryck (2000) for French, based on an
intonational Q-morpheme that surfaces as a final rise in polar and
wh-in-situ questions. We report the outcome of
a production experiment providing evidence that the final rises of
polar and wh-in-situ questions in Navarro-Labourdin
Basque do not differ substantially, thus suggesting that Cheng & Rooryck’s
(2000) proposal may be extended to this variety
cohabiting with French.
Harnessing large-scale biodiversity data to infer the current distribution ofVanilla planifolia(Orchidaceae)
Authors: Ellestad Paige , Forest Félix , Serpe Marcelo , Novak Stephen J , Buerki Sven 
Published: January 2021

AbstractAlthough vanilla is one of the most popular flavours in the world, there is still uncertainty concerning the native distribution of the species that produces it, Vanilla planifolia. To circumscribe the native geographical extent of this economically important species more precisely, we propose a new landscape-based approach to incorporate information from open-source databases and validate occurrences. In this approach, we include metrics to account for habitat suitability and population sustainability in terms of the biotic (co-occurrence of pollinators and dispersers) and abiotic (habitat quality) factors limiting plant distributions. To further validate occurrences within the resulting distribution, we compare the presence of morphologically similar wild relatives, assess the heterogeneity of ecological niches and verify the correct identification of herbarium specimens. Results from this approach suggest that V. planifolia has a larger geographical distribution than previously recognized; we hypothesize that populations naturally dispersed from Mesoamerica and became established in South America (with a south-eastern limit in Brazil). The recognition of an improved estimate of the distribution of this species will increase the accuracy of predictive models, promote further species circumscription, improve the efficacy of conservation strategies, and help to ensure the sustainability of a valuable, sought-after spice.
TETRASOMIC SEGREGATION FOR MULTIPLE ALLELES IN ALFALFA
Authors: Quiros Carlos F 
Published: January 2021

ABSTRACT
Evidence of tetrasomic inheritance in alfalfa, Medicago sativa L. and M. falcata L., for multiple codominant alleles at three isozymic loci is reported in this study. The locus Prx-1 governing anodal peroxidase and the loci Lap-1 and Lap-2 governing anodal leucine-aminopeptidase were studied by starch gel electrophoresis in seedling root tissue or seeds. The progenies from several di-, tri- or tetra-allelic plants belong to the species M. sativa and M. falcata and their hybrids were studied for the segregation of the three genes. In all cases, tetrasomic inheritance of chromosomal-type segregation was observed. In another progeny resulting from the crossing of two plants involving four different alleles at locus Lap-2, tetrasomic segregation with the possible occurrence of double reduction was observed. This study presents direct evidence of autotetraploidy and the existence of tetra-allelic loci in alfalfa. It also supports the concept that the species M. sativa and M. falcata are genetically close enough to be considered biotypes of a common species.
TWO DISTINCT PANCREATIC AMYLASE GENES ARE ACTIVE IN YBR MICE
Authors: Strahler John R , Meisler Miriam 
Published: January 2021

ABSTRACT
The genetic determinants of pancreatic amylase expression in YBR mice differ in two respects from those of other inbred strains. First, there are two nonallelic amylase isozymes present in YBR pancreas, while most mouse strains express a single pancreatic amylase protein. In addition, the in vivo rate of total pancreatic amylase synthesis is 50% of that in other strains. Both these traits are determined by genetic sites in the region of the Amy-2 locus on mouse chromosome 3. To determine the molecular basis for the presence of two isozymes in this strain, we have compared portions of their amino acid sequences. Two differences between isozymes A1 and B1 were identified among the 77 residues compared. This result demonstrates that two distinct amylase genes are expressed in YBR pancreas.
Q BAND CHROMOSOMAL POLYMORPHISMS IN LAKE TROUT (SALVELINUS NAMAYCUSH)
Authors: Phillips Ruth B , Zajicek Kerry D 
Published: January 2021

ABSTRACT
Q banding of chromosome preparations from lake trout revealed the presence of heteromorphic quinacrine bright bands on several chromosomes. All of the metacentric chromosome pairs can be distinguished on the basis of number, position and intensity of the quinacrine bright bands and chromosome size. These bands appear to represent heterochromatin, since they are darkly staining with the C band technique. Since all of the fish examined had consistent heteromorphisms at several of the quinacrine bright bands, these chromosome markers should be useful in genetic comparisons between different trout stocks and populations.
GENETIC FINE STRUCTURE OF THE Y CHROMOSOME OF DROSOPHILA HYDEI
Authors: Hackstein Johannes H P , Leoncini Orilio , Beck Heinz , Peelen Gijsbert , Hennig Wolfgang 
Published: January 2021

ABSTRACT
A genetic map of the Y chromosome of Drosophila hydei has been constructed from deletion/complementation experiments, with the aid of male sterile mutants of the Y chromosome. A central conclusion of our experiments is that not more than a single complementation group can be detected in each of the lampbrush loop forming sites. Additional complementation groups, functionally independent of lampbrush loops, reside between these loci. Six complementation groups have been defined by several methods of mapping. An additional ten complementation groups are indicated, but their exact definition requires further investigation. The "synthetic sterility" of mutations in these ten loci contributes to the difficulty in unequivocally establishing their individual boundaries. Mapping problems also arise from the instability of certain mutants.
NATURAL SELECTION AND FITNESS ENTROPY IN A DENSITY-REGULATED POPULATION
Authors: Desharnais R A , Costantino R F 
Published: January 2021

ABSTRACT
The entropy H(po,p*) of a population with the initial allele frequency po given the equilibrium polymorphic frequency p* has been proposed as a measure of natural selection. In the present paper, we have extended this concept to include a particular aspect of density-dependent selection. We compared size trajectory of a population initially at genetic equilibrium, N(t), with the size trajectories of populations not initially at p*,N(t), but which do eventually converge to a common equilibrium allele frequency and equilibrium density, N*. The following experimentally testable hyopthesis was established. The total area defined by the difference between the trajectories of N(t) and N(t) as they converge to N* is directly proportional to the fitness entropy when population size is transformed using the density-dependent fitness value. Two properties of this relationship were noted. First, it is independent of the magnitude of natural selection and, secondly, it does not depend upon the initial population density as long as the equilibrium and nonequilibrium populations have the same initial numbers. This hypothesis was evaluated with experimental data on the flour beetle Tribolium castaneum.
RE-INTERPRETATION OF GENETIC VARIATION IN SIMOCEPHALUS (CLADOCERA, DAPHNIIDAE)
Authors: Hann B J , Hebert P D N 
Published: January 2021

ABSTRACT
Populations of several co-existing species of Simocephalus were examined electrophoretically at 11 enzyme loci. The prevailing pattern was one of extensive allelic substitution between species and low levels of polymorphism (0-10%) within species. Genetic identity values between species were very low (10-50%). These results concur with those for other cyclic parthenogens, but are in sharp contrast to previous interpretation of data derived from populations of Simocephalus from the same sites.
SPORE KILLER POLYMORPHISM IN FUSARIUM MONILIFORME
Authors: Kathariou Sophia , Spieth Philip T 
Published: January 2021

ABSTRACT
A Spore killer trait, which exhibits genetic and cytological properties analogous to those previously found in Neurospora, exists in natural populations of the fungal plant pathogen Fusarium moniliforme. The genogeography of the polymorphism in F. moniliforme differs from the situation in Neurospora intermedia. It is more akin to the situation in N. sitophila, although more extreme with respect to the prevalence of killer alleles: more than 80% of tested isolates of F. moniliforme carry the killer allele. Nevertheless, sensitive alleles are widely distributed and have been found in California, Italy, Greece and Central America.
CHROMOSOME INTERACTIONS IN DROSOPHILA MELANOGASTER. I. VIABILITY STUDIES
Authors: Seager Robert D , Ayala Francisco J 
Published: January 2021

ABSTRACT
The nature of fitness interactions is an important, yet unsolved, question in population genetics. We compare the egg-to-adult viability of individuals homozygous for either a second or a third chromosome with the viability of individuals homozygous for both chromosomes simultaneously. On the average, the viability of the two-chromosome homozygotes is somewhat greater than expected assuming that the fitnesses of the single-chromosome homozygotes interact in a multiplicative fashion. This result differs from previous observations that indicate either no significant deviations from the expectation or lower-than-expected average fitnesses for the double homozygotes.
MALE COURTSHIP IN DROSOPHILA: THE CONDITIONED RESPONSE TO IMMATURE MALES AND ITS GENETIC CONTROL
Authors: Gailey Donald A , Jackson F Rob , Siegel Richard W 
Published: January 2021

ABSTRACT
Experimentally naive male Drosophila melanogaster respond to sexually immature males with intense courtship. However, this response decreases markedly in a short period of time, and "experienced" males then avoid further courtship with immature males for 4 hr. This subsequent inhibition of the courtship response is specific to immature males; the response to virgin females remains intact. This experience-dependent modification in courtship behavior is designated as "conditioned courtship." Seven mutant strains isolated for their inability to express avoidance conditioning (on criteria independent of courtship) were all found to be mutant with respect to expression of conditioned courtship. The potential application of this phenomenon to mosaic analysis of these mutations is posed. Other results indicate that immature males constitutively release a chemical signal that is sufficient for the expression of conditioned courtship. The interpretation of conditioned courtship as a component of fitness is discussed.
DIETARY EFFECTS ON FITNESS COMPONENTS AT THE PGM-1 LOCUS OF TRIBOLIUM CASTANEUM
Authors: Riddle Russel A , Iverson Victoria , Dawson Peter S 
Published: January 2021

ABSTRACT
The pattern of genetic differentiation among experimental populations of the flour beetle Tribolium castaneum suggested the hypothesis that relative fitness of three genotypes at the PGM-1 locus (or other linked loci) depends directly on diet. This hypothesis was tested by measuring several fitness components (developmental time, survival, fecundity, rate of egg cannibalism) on groups of individuals differing at the PGM-1 locus that were reared on three types of flour (wheat, corn and a mixture of wheat, corn, barley and rye). Flour type had large effects on all traits except larval survival to 3 weeks of age. Relative fitnesses of the three genotypes differed significantly for fecundity. Diet was found to significantly influence the relative developmental times of the three genotypes.
GENES CONTROLLING MATING-TYPE SPECIFICITY IN PARAMECIUM CAUDATUM: THREE LOCI REVEALED BY INTERSYNGENIC CROSSES
Authors: Tsukii Yuuji , Hiwatashi Koichi 
Published: January 2021

ABSTRACT
In mating interactions in Paramecium caudatum, initial mating agglutination is strictly mating-type specific, but subsequent conjugating pair formation is not mating-type specific. Using this nonspecificity of pair formation, intersyngenic (intersibling species) pairs were induced by mixing four mating types of two different syngens. To distinguish intersyngenic pairs from intrasyngenic ones, the behavioral marker CNR (Takahashi 1979) was mainly used. Clones of intersyngenic hybrids showed high fertility and thus made feasible a genetic analysis of syngenic specificity of mating type. The syngenic specificities of E (even) mating types were found to be controlled by co-dominant multiple alleles at the Mt locus, and those of O (odd) mating types by interactions of co-dominant multiple alleles at two loci, MA and MB. Clones of heterozygotes express dual mating types. Mt is epistatic to MA and MB, and thus O mating types can be expressed only in the recessive homozygote (mt/mt) at the Mt locus. In addition, at least one allele each at the MA and MB loci must have a common syngen specificity for the expression of O types. Thus, when MA is homozygous for one syngen and MB is homozygous for another syngen, no mating type is expressed.
HYBRID DYSGENESIS IN DROSOPHILA MELANOGASTER: FACTORS AFFECTING CHROMOSOMAL CONTAMINATION IN THE P-M SYSTEM
Authors: Kidwell Margaret G 
Published: January 2021

ABSTRACT
The two interacting components of the P-M system of hybrid dysgenesis are chromosomally associated elements called P factors and a susceptible cytoplasmic state referred to as M cytotype. Previous experiments have indicated that P factors are a family of multiple-copy transposable genetic elements dispersed throughout the genome of P strains but absent in long-established M strains.—Evidence is presented that the sterility and male recombination-inducing potential of P elements may be acquired by X chromosomes, derived from M strains, through nonhomologous association with P strain autosomes, a process referred to as "chromosomal contamination." The frequencies of chromosomal contamination of X chromosomes by P strain autosomes were highly variable and depended on a number of factors. M cytotype (as opposed to P cytotype) was essential for high frequencies of P factor contamination. There were large differences in contamination potential among individual female families, and a weak negative correlation existed between family size and contamination frequency. Chromosomal contamination in the P-M system was shown to be independent of that in the I-R system.—Frequency distributions suggested that the relationship between sterility production and P factor insertion is complex. The majority of P element transpositions, identified by in situ hybridization in one X chromosome, were not associated with gonadal sterility. However, high sterility potential was found to be associated with the presence of at least one P element inserted into the X chromosome. This potential was lost at a rate of about one-sixth per generation in M cytotype but was stabilized in P cytotype. Various hypotheses concerning the relationship between transposition and chromosomal contamination are discussed.
THE GENETICS OF A SMALL AUTOSOMAL REGION OF DROSOPHILA MELANOGASTER CONTAINING THE STRUCTURAL GENE FOR ALCOHOL DEHYDROGENASE. VI. INDUCED REVERTANTS OF SCUTOID
Authors: Ashburner M , Detwiler C , Tsubota S , Woodruff R C 
Published: January 2021

ABSTRACT
Twenty-six induced revertants of Scutoid (Sco), a dominant mutation of Drosophila melanogaster, have been characterized genetically. Sco is an unusual mutation, involving two small reciprocal transpositions within the region 35A4 to 35C5 of chromosome arm 2L. One of these transpositions juxtaposes the noc and l(2)br28 loci. We suggested previously that the Sco phenotype results from the "fusion" of noc and l(2)br28. In support of this idea we now show that 23 of 26 revertants of Sco are noc -, indeed the majority are either chromosome aberrations broken between noc and l(2)br28 or deletions of these loci from the mutant chromosome. However, some revertants of Sco are rather more complex, and their properties suggest an interaction between the pu-noc and l(2)br28-l(2)br37 regions of chromosome arm 2L and also demonstrate the genetic complexity of the el-noc region.