bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improving soil fertility for maize (Zea mays L.) production using inorganic and organic fertilizer: A case of N: P: K 15: 15: 15 and biomass of Agroforestry trees
Authors: Agyeman K. , Afuakwa J. J. , Danquah E. Owusu , Asubonteng K. O. 
Published: August 2021

With increased pressure on cropping land, traditional soil fertility regeneration has become less effective. Farmers with no alternatives would therefore be compelled to cultivate on marginal lands, highly risking crop failure and food security. Soil fertility can be improved by employing Agroforestry principles of incorporating organic inputs into the soil. This study investigated the effects of leaf mulch of Gliricidia sepium, Senna siamea and Leucaena leucocephala and their combination with inorganic fertilizer on maize (Zea mays L) growth and yield. The study was conducted in a randomized completely block design at the Faculty of Renewable Natural Resource farm, KNUSTGhana. Fresh leaf biomass at 5 t haÂ]1 weight was incorporated into the soil and compared with the addition of inorganic fertilizer at 0, 30 and 60 kg N ha Â]1 levels. Soil laboratory analysis showed that the mineral content of the leaf biomass varied with L. leucocephala having the highest N content and S. siamea having the lowest N content. The addition of the different levels of the inorganic fertilizer to the leaf biomass significantly influenced the yield of maize. Combining leaf biomass of S. siamea, G. sepium and L. leucocephala with inorganic fertilizer significantly increased maize yield and can be recommended for improving maize and other crop production.
Lime and organic manure effect on acidÂ]clay soil, Okra growth and yield parameters
Authors: Ewulo B. S. 
Published: August 2021

Two potted experiments were conducted at the screenÂ]house of the Department of Crop, Soil and Pest Management of the Federal University of Technology, Akure to investigate the effects of lime and different levels of organicmanure amendment on acidÂ]clay soil, Okra growth and yield parameters.The first experiment consisted of six treatments and a control; choppedTithonia diversifolia leaves were applied on limed soil (100g lime kgÂ]1 Soil) at0g, 6.75g, 13.5g, 20.25g, 27.0g and 33.75g kgÂ]1 Soil. The second experimentalso consisted of six treatments and a control; poultry manure was appliedon limed soil (100g lime kgÂ]1 Soil) at 0g, 6.75g, 13.5g, 20.25g, 27.0g and33.75g kgÂ]1 Soil. They were arranged in Complete Randomized Design. Soilsamples were collected at the 2nd, 4th, and 6th, week after planting and subjected to chemical analysis. Okra growth and yield data were collected and statistical analyses carried out using the SPSS Package and means compared with Duncan Multiple Range Test (DMRT) at 5% level of probability. The result of the study showed that soil pH, OC, OM, N, P, K, Ca, Na, Mg and CEC increased with lime application and with increases in rate of Tithonia leaves or poultry manure application. There were no significant differences in most of the soil parameters considered in Tithonia and poultry manure applied at 27.0g and 33.75 g kg Â]1 soil. Growth parameters showed no significant differences for the two experiments except with regards to number of leaves in Tithonia application. Application of 33.75g Tithonia kgÂ]1 gave the highest Okra pod weight for Tithonia treated soil while the application of 27g poultry manure kgÂ]1 gave highest Okra weight for poultry manure treated soil.
Electrochemical, Mineral and Microbiological studies of soil samples collected from three different altitudinal climatic zones in Tamil Nadu
Authors: Perumal K. , Moorthy T. Sambanda , Ponsugumari P. , Malleswari R. B. , Karthik B. , Krishna K. V. , Ananthi S. , Kumar J. Arun 
Published: August 2021

Seventy five surface (10 â€15 cm) soil samples from three different altitudinal climatic zones viz., Kodaikanal (temp 9â€13°C, altitudinal height 2133 m, black soil), Valparai (temp 15â€22°C, altitudinal height 1700 m, clay loam soil) and Sethumadai (temp 27â€33°C, altitudinal height 100 m, red sandy soil) of Tamil Nadu were collected and analyzed for their pH, Electron Conductivity (EC), Organic Carbon (OC%), Humus, macro and micronutrients. Soil enzyme activities such as protease, alkaline phosphatase, cellulase, invertase, soil microbial enumeration such as total bacterial count, fungi, rhizobium and actinomycetes were also determined by following standard procedures. The soil was acidic and high content of OC (2.12%), humus (396 mg Kgâ€1), N (474.1±30 mg Kgâ€1), P (52.92±6 mg Kgâ€1), K (163.7±20 mg Kgâ€1), Ca (545.2±25 mg Kgâ€1), S (25.35±13 mg Kgâ€1), B (0.95±2 mg Kgâ€1), Cu (2.38±0.9 mg Kgâ€1), Fe (32.54±14 mg Kgâ€1), Mn (9.44±7 mg Kgâ€1) and Zn (3.58±1 mg Kgâ€1) were recorded in soil samples collected from Kodaikanal. Most of the soil samples collected from Kodaikanal recorded maximum macro and micronutrients except Na (79.81±10 mg Kgâ€1) and Mg (124.81±20 mg Kgâ€1) when compared with Valparai and Sethumadai. Soil enzyme activity and microbial count were also high in soil samples collected from Kodaikanal followed by Valparai and Sethumadai, whereas actinomycetes (4±1 CFU x 10â€6 gâ€1) count was high in Sethumadai of lower altitude. The study revealed that the activity of soil microbial population was high at higher altitude due to the presence of high content OC (2.82%) and quick decomposition of organic matter. The quality of soil was subjected to circular paper chromatographic analysis and it revealed difference in colour, pattern and the number of spikes were the indicators of soil fertility.
Cataclysmic Variables in the Second Year of the Zwicky Transient Facility
Authors: Szkody Paula , Olde Loohuis Claire , Koplitz Brad , van Roestel Jan , Dicenzo Brooke , Ho Anna Y. Q. , Hillenbrand Lynne A. , Bellm Eric C. , Dekany Richard , Drake Andrew J. , Duev Dmitry A. , Graham Matthew J. , Kasliwal Mansi M. , Mahabal Ashish A. , Masci Frank J. , Neill James D. , Riddle Reed , Rusholme Benjamin , Sollerman Jesper , Walters Richard 
Published: August 2021

Abstract
Using a filter in the GROWTH Marshal based on color and the amplitude and timescale of variability, we have identified 372 objects as known or candidate cataclysmic variables (CVs) during the second year of the operation of the Zwicky Transient Facility. From the available difference imaging data, we found that 93 are previously confirmed CVs and 279 are strong candidates. Spectra of four of the candidates confirm them as CVs by the presence of Balmer emission lines, while one of the four has prominent He ii lines indicative of containing a magnetic white dwarf. Gaia EDR3 parallaxes are available for 154 of these systems, resulting in distances from 108–2096 pc and absolute magnitudes in the range of 7.5–15.0, with the largest number of candidates between 10.5 and 12.5. The total numbers are 21% higher than from the previous year of the survey with a greater number of distances available but a smaller percentage of systems close to the Galactic plane. Comparison of these findings with a machine-learning method of searching all the light curves reveals large differences in each data set related to the parameters involved in the search process.
Stars with Photometrically Young Gaia Luminosities Around the Solar System (SPYGLASS). I. Mapping Young Stellar Structures and Their Star Formation Histories
Authors: Kerr Ronan M. P. , Rizzuto Aaron C. , Kraus Adam L. , Offner Stella S. R. 
Published: August 2021

Abstract
Young stellar associations hold a star formation record that can persist for millions of years, revealing the progression of star formation long after the dispersal of the natal cloud. To identify nearby young stellar populations that trace this progression, we have designed a comprehensive framework for the identification of young stars and use it to identify ∼3 × 104 candidate young stars within a distance of 333 pc using Gaia DR2. Applying the HDBSCAN clustering algorithm to this sample, we identify 27 top-level groups, nearly half of which have little to no presence in previous literature. Ten of these groups have visible substructure, including notable young associations such as Orion, Perseus, Taurus, and Sco-Cen. We provide a complete subclustering analysis of all groups with substructure, using age estimates to reveal each region’s star formation history. The patterns we reveal include an apparent star formation origin for Sco-Cen along a semicircular arc, as well as clear evidence for sequential star formation moving away from that arc with a propagation speed of ∼4 km s−1 (∼4 pc Myr−1). We also identify earlier bursts of star formation in Perseus and Taurus that predate current, kinematically identical active star-forming events, suggesting that the mechanisms that collect gas can spark multiple generations of star formation, punctuated by gas dispersal and cloud regrowth. The large spatial scales and long temporal scales on which we observe star formation offer a bridge between the processes within individual molecular clouds and the broad forces guiding star formation at galactic scales.
Observations and Analysis of CH+ Vibrational Emissions from the Young, Carbon-rich Planetary Nebula NGC 7027: A Textbook Example of Chemical Pumping
Authors: Neufeld David A. , Godard Benjamin , Bryan Changala P. , Faure Alexandre , Geballe T. R. , Güsten Rolf , Menten Karl M. , Wiesemeyer Helmut 
Published: August 2021

Abstract
We discuss the detection of 14 rovibrational lines of CH+, obtained toward the planetary nebula NGC 7027 with the iSHELL spectrograph on NASA’s Infrared Telescope Facility (IRTF) on Maunakea. Our observations in the 3.49–4.13 μm spectral region, obtained with a 0.″375 slit width that provided a spectral resolving power λ/Δλ ∼ 80,000, have resulted in the unequivocal detection of the R(0)−R(3) and P(1)−P(10) transitions within the v = 1−0 band of CH+. The R-branch transitions are anomalously weak relative to the P-branch transitions, a behavior that is explained accurately by rovibronic calculations of the transition dipole moment reported in a companion paper. Nine infrared transitions of H2 were also detected in these observations, comprising the S(8), S(9), S(13), and S(15) pure rotational lines; the v = 1−0 O(4)−O(7) lines; and the v = 2−1 O(5) line. We present a photodissociation model, constrained by the CH+ and H2 line fluxes that we measured, that includes a detailed treatment of the excitation of CH+ by inelastic collisions, optical pumping, and chemical (“formation”) pumping. The latter process is found to dominate the excitation of the observed rovibrational lines of CH+, and the model is remarkably successful in explaining both the absolute and relative strengths of the CH+ and H2 lines.
Evidence for Radial Expansion at the Core of the Orion Complex with Gaia EDR3
Authors: Swiggum Cameren , D’Onghia Elena , Alves João , Großschedl Josefa , Foley Michael , Zucker Catherine , Meingast Stefan , Chen Boquan , Goodman Alyssa 
Published: August 2021

Abstract
We present a phase-space study of two stellar groups located at the core of the Orion Complex: Briceño-1 and Orion Belt Population-near (OBP-near). We identify the groups with the unsupervised clustering algorithm, Shared Nearest Neighbor (SNN), which previously identified 12 new stellar substructures in the Orion Complex. For each of the two groups, we derive the 3D space motions of individual stars using Gaia EDR3 proper motions supplemented by radial velocities from Gaia DR2, APOGEE-2, and GALAH DR3. We present evidence for radial expansion of the two groups from a common center. Unlike previous work, our study suggests that evidence of stellar group expansion is confined only to OBP-near and Briceño-1, whereas the rest of the groups in the complex show more complicated motions. Interestingly, the stars in the two groups lie at the center of a dust shell, as revealed via an extant 3D dust map. The exact mechanism that produces such coherent motions remains unclear, while the observed radial expansion and dust shell suggest that massive stellar feedback could have influenced the star formation history of these groups.
Evidence Suggesting That ‘Oumuamua Is the ∼30 Myr Old Product of a Molecular Cloud
Authors: Hsieh Cheng-Han , Laughlin Gregory , Arce Héctor G. 
Published: August 2021

Abstract
The appearance of interstellar objects (ISOs) in the solar system—and specifically the arrival of 1I/‘Oumuamua—points to a significant number density of free-floating bodies in the solar neighborhood. We review the details of ‘Oumuamua’s pre-encounter Galactic orbit, which intersected the solar system at very nearly its maximum vertical and radial excursion relative to the Galactic plane. These kinematic features are strongly emblematic of nearby young stellar associations. We obtain an a priori order-of-magnitude age estimate for ‘Oumuamua by comparing its orbit to the orbits of 50,899 F-type stars drawn from Gaia DR2; a diffusion model then suggests a ∼35 Myr dynamical age. We compare ‘Oumuamua’s orbit with the trajectories of individual nearby moving groups, confirming that its motion is fully consistent with membership in the Carina (CAR) moving group with an age of ~30 Myr. We conduct Monte Carlo simulations that trace the orbits of test particles ejected from the stars in the CAR association. The simulations indicate that in order to uniformly populate the ∼106 pc3 volume occupied by CAR members with the inferred number density, n = 0.2 au−3, of ISOs implied by Pan-STARRS’s detection of ‘Oumuamua, the required ejection mass is M ∼ 500 M
Jup per known star within the CAR association. This suggests that the Pan-STARRS observation is in significant tension with scenarios that posit ‘Oumuamua’s formation and ejection from a protostellar disk.
The Palomar Transient Factory Core-collapse Supernova Host-galaxy Sample. I. Host-galaxy Distribution Functions and Environment Dependence of Core-collapse Supernovae
Authors: Schulze Steve , Yaron Ofer , Sollerman Jesper , Leloudas Giorgos , Gal Amit , Wright Angus H. , Lunnan Ragnhild , Gal-Yam Avishay , Ofek Eran O. , Perley Daniel A. , Filippenko Alexei V. , Kasliwal Mansi M. , Kulkarni Shrinivas R. , Neill James D. , Nugent Peter E. , Quimby Robert M. , Sullivan Mark , Strotjohann Nora Linn , Arcavi Iair , Ben-Ami Sagi , Bianco Federica , Bloom Joshua S. , De Kishalay , Fraser Morgan , Fremling Christoffer U. , Horesh Assaf , Johansson Joel , Kelly Patrick L. , Knežević Nikola , Knežević Sladjana , Maguire Kate , Nyholm Anders , Papadogiannakis Seméli , Petrushevska Tanja , Rubin Adam , Yan Lin , Yang Yi , Adams Scott M. , Bufano Filomena , Clubb Kelsey I. , Foley Ryan J. , Green Yoav , Harmanen Jussi , Ho Anna Y. Q. , Hook Isobel M. , Hosseinzadeh Griffin , Howell D. Andrew , Kong Albert K. H. , Kotak Rubina , Matheson Thomas , McCully Curtis , Milisavljevic Dan , Pan Yen-Chen , Poznanski Dovi , Shivvers Isaac , van Velzen Sjoert , Verbeek Kars K. 
Published: August 2021

Abstract
Several thousand core-collapse supernovae (CCSNe) of different flavors have been discovered so far. However, identifying their progenitors has remained an outstanding open question in astrophysics. Studies of SN host galaxies have proven to be powerful in providing constraints on the progenitor populations. In this paper, we present all CCSNe detected between 2009 and 2017 by the Palomar Transient Factory. This sample includes 888 SNe of 12 distinct classes out to redshift z ≈ 1. We present the photometric properties of their host galaxies from the far-ultraviolet to the mid-infrared and model the host-galaxy spectral energy distributions to derive physical properties. The galaxy mass function of Type Ic, Ib, IIb, II, and IIn SNe ranges from 105 to 1011.5
M
⊙, probing the entire mass range of star-forming galaxies down to the least-massive star-forming galaxies known. Moreover, the galaxy mass distributions are consistent with models of star-formation-weighted mass functions. Regular CCSNe are hence direct tracers of star formation. Small but notable differences exist between some of the SN classes. Type Ib/c SNe prefer galaxies with slightly higher masses (i.e., higher metallicities) and star formation rates than Type IIb and II SNe. These differences are less pronounced than previously thought. H-poor superluminous supernovae (SLSNe) and SNe Ic-BL are scarce in galaxies above 1010
M
⊙. Their progenitors require environments with metallicities of < 0.4 and < 1 solar, respectively. In addition, the hosts of H-poor SLSNe are dominated by a younger stellar population than all other classes of CCSNe. Our findings corroborate the notion that low metallicity and young age play an important role in the formation of SLSN progenitors.
Evolution of Cold Gas at 2 < z < 5: A Blind Search for H i and OH Absorption Lines toward Mid-infrared Color-selected Radio-loud AGN
Authors: Gupta N. , Srianand R. , Shukla G. , Krogager J-. K. , Noterdaeme P. , Combes F. , Dutta R. , Fynbo J. P. U. , Hilton M. , Momjian E. , Moodley K. , Petitjean P. 
Published: August 2021

Abstract
We present results from a spectroscopically blind search for associated and intervening H i 21 cm and OH 18 cm absorption lines toward 88 active galactic nuclei (AGN) at 2 ≤ z ≤ 5 using the uGMRT. The sample of AGN with 1.4 GHz spectral luminosity in the range 1027−29.3 W Hz−1 is selected using mid-infrared colors and closely resembles the distribution of the underlying quasar population. The search for associated or proximate absorption, defined to be within 3000 km s−1 of the AGN redshift, led to one H i 21 cm absorption detection (M1540−1453; z
abs = 2.1139). This is only the fourth known absorption at z > 2. The detection rate (

1.6

−
1.4

+
3.8

%) suggests a low covering factor of the cold neutral medium (CNM; T ∼ 100 K) associated with these powerful AGN. The intervening absorption line search, with a sensitivity to detect the CNM in damped Lyα systems (DLAs), has comoving absorption path lengths of ΔX = 130.1 and 167.7 for H i and OH, respectively. The corresponding number of absorbers per unit comoving path length are ≤0.014 and ≤0.011, respectively. The former is at least 4.5 times lower than that of DLAs and consistent with the CNM cross section estimated using H2 and C i absorbers at z > 2. Our AGN sample is optically fainter compared to the quasars used to search for DLAs in the past. In our optical spectra obtained using SALT and NOT, we detect five intervening (redshift path ∼9.3) and two proximate DLAs. This is slightly excessive compared to the statistics based on optically selected quasars. The nondetection of H i 21 cm absorption from these DLAs suggests a small CNM covering fraction around galaxies at z > 2.
Atomic Transition Probabilities of Neutral Calcium*
Authors: Den Hartog E. A. , Lawler J. E. , Sneden C. , Cowan J. J. , Roederer I. U. , Sobeck J. 
Published: August 2021

Abstract
The goals of this study are (1) to test the best theoretical transition probabilities for Ca i (a relatively light alkaline earth spectrum) from a modern ab initio calculation using configuration interaction plus many-body perturbation theory against the best modern experimental transition probabilities and (2) to produce as accurate and comprehensive a line list of Ca i transition probabilities as is currently possible based on this comparison. We report new Ca i radiative lifetime measurements from a laser-induced fluorescence experiment and new emission branching fraction measurements from a 0.5 m focal length grating spectrometer with a detector array. We combine these data for upper levels that have both a new lifetime and new branching fractions to report log(gf) values for two multiplets consisting of nine transitions. Detailed comparisons are made between theory and experiment, including the measurements reported herein and a selected set of previously published experimental transition probabilities. We find that modern theory compares favorably to experimental measurements in most instances where such data exist. A final list of 202 recommended transition probabilities is presented, which covers lines of Ca i with wavelengths ranging from 2200 to 10000 Å. These are mostly selected from theory but are augmented with high-quality experimental measurements from this work and from the literature. The recommended transition probabilities are used in a redetermination of the Ca abundance in the Sun and in the metal-poor star HD 84937.
A Recipe for the Geophysical Exploration of Enceladus
Authors: Ermakov Anton I. , Park Ryan S. , Roa Javier , Castillo-Rogez Julie C. , Keane James T. , Nimmo Francis , Kite Edwin S. , Sotin Christophe , Lazio T. Joseph W. , Steinbrügge Gregor , Howell Samuel M. , Bills Bruce G. , Hemingway Douglas J. , Viswanathan Vishnu , Tobie Gabriel , Lainey Valery 
Published: August 2021

Abstract
Orbital geophysical investigations of Enceladus are critical to understanding its energy budget. In this paper, we identified key science questions for the geophysical exploration of Enceladus, answering which would support future assessment of Enceladus’ astrobiological potential. Using a Bayesian framework, we explored how science requirements map to measurement requirements. We performed mission simulations to study the sensitivity of single-spacecraft and dual-spacecraft configurations to static gravity and tidal Love numbers of Enceladus. We find that mapping Enceladus’ gravity field, improving the accuracy of the physical libration amplitude, and measuring Enceladus’ tidal response would provide critical constraints on the internal structure and establish a framework for assessing Enceladus’ long-term habitability. This kind of investigation could be carried out as part of a life search mission at little additional resource requirements.
La propagande allemande par le livre
Authors: Puren Marie 
Published: August 2021

Entre 1941 et 1944, les éditions Ferenczi ont été sous contrôle allemand. « Aryanisées » et dirigées par un administrateur complaisant, elles ont été mises au service des desseins allemands, avec pour objectif de convertir les Français à la collaboration. L’histoire de cette maison d’édition pendant la guerre offre un aperçu complet des mesures utilisées par les occupants pour pénétrer et contrôler l’édition française et pour diffuser leur matériel de propagande. Mais les résultats ne semblent pas avoir été à la hauteur des efforts investis. Cet article tente de comprendre quelles ont été les raisons de cet échec, et plus globalement de celui de la propagande allemande par le livre, en examinant le fonctionnement de ces maisons d’éditions.
La promotion d’une érudition locale comme expertise
Authors: Garnier Gautier 
Published: August 2021

Cet article analyse la conversion d’une tradition d’érudition locale sur la ville de Lisbonne (« l’olisipographie ») en expertise tournée vers l’action municipale, entre les années 1930 et la décennie 1950. Ce phénomène est rendu possible par la fermeture sociopolitique de la municipalité lisboète (CML) sous l’Estado Novo salazariste. La CML contribue à l’institutionnalisation de l’olisipographie tandis que cette dernière lui fournit un ensemble de savoirs sur la ville. Les olisipographes sont portés par un groupement de notables (le Grupo Amigos de Lisboa) qui se pose en interprète des intérêts des Lisboètes. S’ils s’affirment comme des mémoriens, c’est-à-dire des experts en mémoire, ils échouent toutefois à faire prévaloir leurs idées en matière d’urbanisme.