cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Integer topological defects of cell monolayers -- mechanics and flows
Creators: name: Blanch-Mercader, Carles
name: Guillamat, Pau
name: Roux, Aurélien
name: Kruse, Karsten
Publisher: name: arXiv
Year: 2020
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: Materials Science (cond-mat.mtrl-sci)
subject: Tissues and Organs (q-bio.TO)
subject: FOS: Physical sciences
subject: FOS: Biological sciences

description: Monolayers of anisotropic cells exhibit long-ranged orientational order and topological defects. During the development of organisms, orientational order often influences morphogenetic events. However, the linkage between the mechanics of cell monolayers and topological defects remains largely unexplored. This holds specifically at the time scales relevant for tissue morphogenesis. Here, we build on the physics of liquid crystals to determine material parameters of cell monolayers. In particular, we use a hydrodynamical description of an active polar fluid to study the steady-state mechanical patterns at integer topological defects. Our description includes three distinct sources of activity: traction forces accounting for cell-substrate interactions as well as anisotropic and isotropic active nematic stresses accounting for cell-cell interactions. We apply our approach to C2C12 cell monolayers in small circular confinements, which form isolated aster or spiral topological defects. By analyzing the velocity and orientational order fields in spirals as well as the forces and cell number density fields in asters, we determine mechanical parameters of C2C12 cell monolayers. Our work shows how topological defects can be used to fully characterize the mechanical properties of biological active matter.
description: 41 pages, 11 figures
Controlling the ac Stark effect of RbCs with dc electric and magnetic fields
Creators: name: Blackmore, Jacob A.
name: Sawant, Rahul
name: Gregory, Philip D.
name: Bromley, Sarah L.
name: Aldegunde, Jesús
name: Hutson, Jeremy M.
name: Cornish, Simon L.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: Quantum Gases (cond-mat.quant-gas)
subject: FOS: Physical sciences

description: We investigate the effects of static electric and magnetic fields on the differential ac Stark shifts for microwave transitions in ultracold bosonic $^{87}$Rb$^{133}$Cs molecules, for light of wavelength $λ= 1064~\mathrm{nm}$. Near this wavelength we observe unexpected two-photon transitions that may cause trap loss. We measure the ac Stark effect in external magnetic and electric fields, using microwave spectroscopy of the first rotational transition. We quantify the isotropic and anisotropic parts of the molecular polarizability at this wavelength. We demonstrate that a modest electric field can decouple the nuclear spins from the rotational angular momentum, greatly simplifying the ac Stark effect. We use this simplification to control the ac Stark shift using the polarization angle of the trapping laser.
RE-CONSIDERING THE NECESSARY CONDITION FOR FUTURES MARKET EFFICIENCY: AN APPLICATION TO DAIRY FUTURES
Creators: name: Sanders, Dwight R.
name: Manfredo, Mark R.
name: Sanders, Dwight R.
name: Manfredo, Mark R.
Publisher: name: Unknown
Year: 2004
Subjects: subject: Marketing
subject: FOS: Economics and business

description: The traditional necessary condition for futures market inefficiency is the existence of alternative forecasting methods that produce mean squared forecast errors smaller than the futures market. Here, a more exacting requirement for futures market efficiency is proposed-forecast encompassing. Using the procedure of Harvey and Newbold, multiple forecast encompassing is tested with the CME fluid milk futures contract. Time series models and experts at the USDA provide the competing forecasts. The results suggest that the CME fluid milk futures do not encompass the information contained in the USDA forecasts at a two-quarter forecast horizon.
Magnetorotational Instability around a Rotating Black Hole
Creators: name: Yokosawa, M.
name: Inui, T.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: The magnetorotational instability(MRI) in the Kerr spacetime is studied on a 3+1 viewpoint. The Maxwell's equations are expressed in a circularly orbiting observer's frame that co-rotates with matter in Keplerian orbits. There exist large proper growth rates in MRI around a rapidly rotating black hole. The large "centrifugal force" and the rapid variations of magnetic fields are caused by the rotation of spacetime geometry. As the result, in the extreme Kerr case the maximum proper growth rate at $r=r_{ms}$ becomes about twelve times as large as that in Schwartzshield case.
description: 18pages, 9figures
THE PERFORMANCE OF WEATHER DERIVATIVES IN MANAGING RISKS OF SPECIALTY CROPS
Creators: name: Fleege, Trevor A.
name: Richards, Timothy J.
name: Manfredo, Mark R.
name: Sanders, Dwight R.
name: Fleege, Trevor A.
name: Richards, Timothy J.
name: Manfredo, Mark R.
name: Sanders, Dwight R.
Publisher: name: Unknown
Year: 2004
Subjects: Crop Production/Industries
Risk and Uncertainty

description: California specialty crop growers are exposed to extreme price volatility, as well as considerable yield volatility caused by fluctuations in temperature, precipitation, and other specific weather events. Weather derivatives do provide a promising market-based solution to managing risks for specialty crops. While previous weather derivatives research has focused on the pricing of weather options, little if any research has been conducted evaluating the hedging effectiveness of these instruments in practical risk management settings. Therefore, this research examines the hedging effectiveness of weather derivative strategies for nectarines, raisin grapes, and almonds in Central California. Estimates of the yield-weather relationships for these crops are found to be non-linear, suggesting a straddle strategy (long put and long call) in weather options. Simulation results also suggest that specialty crop producers can improve their net income distribution through the use of weather derivative strategies. This is particularly true when the correlation between price and yields is low.
Weak identity arrows in higher categories
Creators: name: Kock, Joachim
Publisher: name: arXiv
Year: 2005
Subjects: subject: Category Theory (math.CT)
subject: FOS: Mathematics
subject: 18D05; 18G30

description: There are a dozen definitions of weak higher categories, all of which loosen the notion of composition of arrows. A new approach is presented here, where instead the notion of identity arrow is weakened -- these are tentatively called fair categories. The approach is simplicial in spirit, but the usual simplicial category $Δ$ is replaced by a certain `fat' delta of `coloured ordinals', where the degeneracy maps are only up to homotopy. The first part of this exposition is aimed at a broad mathematical readership and contains also a brief introduction to simplicial viewpoints on higher categories in general. It is explained how the definition of fair $n$-category is almost forced upon us by three standard ideas. The second part states some basic results about fair categories, and give examples. The category of fair 2-categories is shown to be equivalent to the category of bicategories with strict composition law. Fair 3-categories correspond to tricategories with strict composition laws. The main motivation for the theory is Simpson's weak-unit conjecture according to which $n$-groupoids with strict composition laws and weak units should model all homotopy $n$-types. A proof of a version of this conjecture in dimension 3 is announced, obtained in joint work with A. Joyal. Technical details and a fuller treatment of the applications will appear elsewhere.
description: LaTeX, 40 pages. Uses Paul Taylor's diagrams, Peter Kabal's texdraw, and one eps figure. Does not compile with pdflatex. Version v3: expository improvements, more details on the Moore loop space example. 44 pages. Final version to appear in IMRN
Establishing Stable Stepfamilies: The Perspectives of Recoupled Parents, Educators and Family Services Professionals
Creators: name: Cann-Milland, Sonia
Publisher: name: Monash University
Year: 2021
Subjects: Education

description: Stepfamilies are an increasingly prominent societal family form. They are complex and diverse. My research addresses the impact recoupled parents, educators, and family service providers have on the healthy development of stepfamilies. Four case studies explored the unique issues recoupled parents confront raising their step/biological children. In addition, the views of professionals involved with these families were sought, particularly regarding the effectiveness of support. The findings address confusion and ambiguity; communication; transitioning; and, adapting. Change is required in family policy, family law, professional support, and education to address the unique issues that stepfamilies face to support the development of healthy stepfamily forms.
ARE REVISIONS TO USDA CROP PRODUCTION FORECASTS SMOOTHED?
Creators: name: Isengildina, Olga
name: Irwin, Scott H.
name: Good, Darrel L.
name: Isengildina, Olga
name: Irwin, Scott H.
name: Good, Darrel L.
Publisher: name: Unknown
Year: 2004
Subjects: Crop Production/Industries

description: This study investigates the nature of the revision process of USDA corn and soybean production forecasts over the 1970/71 through 2002/03 marketing years. Nordhaus' framework for testing the efficiency of fixed-event forecasts is used. In this framework, efficiency is based on independence of forecast revisions. Both parametric and non-parametric tests reject independence of consecutive forecast revisions. Positive correlation and consistency of directional changes in forecast revisions suggest that these forecasts are "smoothed." Estimates of the impact of smoothing on forecast accuracy show that correction for smoothing may result in economically meaningful improvements in accuracy.
Nonreciprocal second harmonic generation in a magnetoelectric material
Creators: name: Toyoda, Shingo
name: Fiebig, Manfred
name: Arima, Taka-hisa
name: Tokura, Yoshinori
name: Ogawa, Naoki
Publisher: name: arXiv
Year: 2020
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Nonreciprocal devices that allow the light propagation in only one direction are indispensable in photonic circuits and emerging quantum technologies. Contemporary optical isolators and circulators, however, require large size or strong magnetic fields because of the general weakness of magnetic light-matter interactions, which hinders their integration into photonic circuits. Aiming at stronger magneto-optical couplings, a promising approach is to utilize nonlinear optical processes. Here, we demonstrate nonreciprocal magnetoelectric second harmonic generation (SHG) in CuB2O4. SHG transmission changes by almost 100% in a magnetic-field reversal of just 10 mT. The observed nonreciprocity results from an interference between the magnetic-dipole- and electric-dipole-type SHG. Even though the former is usually notoriously smaller than the latter, it is found that a resonantly enhanced magnetic-dipole-transition has a comparable amplitude as non-resonant electric-dipole-transition, leading to the near-perfect nonreciprocity. This mechanism could form one of the fundamental bases of nonreciprocity in multiferroics, which is transferable to a plethora of magnetoelectric systems to realize future nonreciprocal and nonlinear-optical devices.
description: 21 pages, 4 figures
Hedging-Effectiveness of Milk Futures Using Value-At-Risk Procedures
Creators: name: Bamba, Ibrahim
name: Maynard, Leigh J.
name: Bamba, Ibrahim
name: Maynard, Leigh J.
Publisher: name: Unknown
Year: 2004
Subjects: subject: Marketing
subject: FOS: Economics and business

description: The effectiveness of the Class III Milk futures market is analyzed in terms of the reduction in Value-at-Risk (VaR) for milk producers located in four regions: Wisconsin, Northeast, Florida and California. Constant hedge ratios are estimated using Myers and Thompson's (1989) generalized conditional hedge ratio technique, and time-varying hedge ratios are estimated using an exponentially weighted moving average method. After defining milk price risk as the deviation of the actual milk price from its expected value, the effectiveness of uniform hedging strategies in the Class III milk futures market is assessed using three popular methods for VaR calculations: the parametric method, the historical method, and the Monte Carlo simulation method. The results suggest that uniform hedging strategies can reduce substantially the VaR of milk cash price for appropriately chosen hedge length and hedge signals. For example, a uniform hedge placed seven months prior to delivery and triggered at $11.00 cwt reduces the mailbox price tail risk more than the same uniform hedging established four months before delivery. As expected the higher the Class III utilization the more effective hedging seems. The magnitude of the hedging effectiveness seems to depend more on the hedge length and the hedge trigger than on the methodology used to obtain the hedge ratio or the VaR.
A localised subgrid scale model for fluid dynamical simulations in astrophysics II: Application to type Ia supernovae
Creators: name: Schmidt, W.
name: Niemeyer, J. C.
name: Hillebrandt, W.
name: Roepke, F. K.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: The dynamics of the explosive burning process is highly sensitive to the flame speed model in numerical simulations of type Ia supernovae. Based upon the hypothesis that the effective flame speed is determined by the unresolved turbulent velocity fluctuations, we employ a new subgrid scale model which includes a localised treatment of the energy transfer through the turbulence cascade in combination with semi-statistical closures for the dissipation and non-local transport of turbulence energy. In addition, subgrid scale buoyancy effects are included. In the limit of negligible energy transfer and transport, the dynamical model reduces to the Sharp-Wheeler relation. According to our findings, the Sharp-Wheeler relation is insuffcient to account for the complicated turbulent dynamics of flames in thermonuclear supernovae. The application of a co-moving grid technique enables us to achieve very high spatial resolution in the burning region. Turbulence is produced mostly at the flame surface and in the interior ash regions. Consequently, there is a pronounced anisotropy in the vicinity of the flame fronts. The localised subgrid scale model predicts significantly enhanced energy generation and less unburnt carbon and oxygen at low velocities compared to earlier simulations.
description: 13 pages, 10 figures, accepted for publication in Astron. Astrophys.; 3D visualisations not included; complete PDF version can be downloaded from http://www.astro.uni-wuerzburg.de/%7Eschmidt/Paper/SGSModel_II_AA.pdf
The effect of other rhizosphere microorganisms on the ability of Paenibacillus spp. to promote the growth of lodgepole pine (Pinus contorta var. latifolia (Dougl. engelm.))
Creators: name: Bent, Elizabeth
Publisher: name: University of British Columbia
Year: 2009

description: The interaction between lodgepole pine and plant growth-promoting rhizobacteria (PGPR) strains Paenibacillus polymyxa L6 and Pw-2 was examined. Experiments were conducted to determine whether the extent of PGPR-mediated growth promotion seen under gnotobiotic conditions is influenced by the presence of co-inoculated rhizobacteria (Curtobacterium flaccumfaciens PF322 or Pseudomonas fluorescens M20) or a co-inoculated ectomycorrhizal fungus (Rhizopogon subcularescens Smith 11616), whether a change in the extent of PGPR-mediated plant growth promotion is related to (1) a quantitative change in the extent of PGPR population density on or within the root, (2) a qualitative change in PGPR colonization of the root surface (determined using immunofluorescence techniques and confocal laser scanning microscopy), (3) a change in levels of auxins and/or cytokinins within root tissue, and finally whether P. polymyxa L6 and Pw-2 vary in their ability to form spores in the rhizosphere. It was concluded that the extent of P. polymyxa-mediated growth promotion of lodgepole pine can be reduced by the presence of a single rhizobacterial co-inoculant. The decreases in growth promotion were not related to reductions in rhizospheric population densities of PGPR, and were not linked to qualitative changes in the ability of PGPR to colonize specific root surface microsites. Rhizobacteria had strain-specific effects on root hormone levels, and the possibility that decreases in growth promotion are related to the effects of combinations of bacteria on root hormones should be investigated. Pw-2 was found to produce significantly more spores than L6 under the experimental conditions, and the possiblity that Pw-2, but not L6, was identifed as an endophyte on chemically surface-sterilized root tissues due to this fact should be considered. Initial attempts to identify Pw-2 colonization sites in the root interior via confocal microscopy were not successful, and further attempts should be made to verify the endophytic status of Pw-2. Co-inoculating seedlings with P. polymyxa and R. subcularescens did not result in additive growth effects on pines. However, further work is needed to determine if additive growth improvements from P. polymyxa and ectomycorrhizal fungus co-inoculation will occur under different growing conditions, and/or in the presence of different ectomycorrhizal fungi.
THE MARKETING PERFORMANCE OF ILLINOIS CORN AND SOYBEAN PRODUCERS
Creators: name: Hagedorn, Lewis A.
name: Irwin, Scott H.
name: Good, Darrel L.
name: Hagedorn, Lewis A.
name: Irwin, Scott H.
name: Good, Darrel L.
Publisher: name: Unknown
Year: 2004
Subjects: subject: Crop Production/Industries
subject: Marketing
subject: FOS: Economics and business

description: Marketing is viewed as an important component of the farm management process, and poor marketing is often cited as a cause of low farm incomes. However, widespread beliefs about poor performance are not based upon a large body of research, and available evidence is too limited to make definitive conclusions about farmer marketing abilities. This paper examines the actual marketing performance of corn and soybean producers in Illinois. Farmer marketing data is based on the USDA's "Average Producer Price Received" over the period 1975-2002. Marketing performance is assessed using 20- and 24-month average price market benchmarks. A comparison of farmer prices received to the price range for each crop year reveals that in the majority of years producers market their crop in the top- or middle-third of the price range. Despite these findings, farmer prices fell below the average price offered by the market in most normal crop years; weighting these shortfalls by actual production reveals substantial, avoidable income loss. In short crop years, however, farmer prices exceeded the market benchmarks for both crops. Observed farmer marketing performance is explained in the context of price and marketing patterns; farmers appear to market too much of their crop in the latter part of the marketing year, when, in most years, prices are at their lowest. Shifting a portion of sales to the pre-harvest period is proposed as a likely means of improving farmer marketing performance and easing avoidable income loss.
WEATHER DERIVATIVES IN THE PRESENCE OF INDEX AND GEOGRAPHICAL BASIS RISK: HEDGING DAIRY PROFIT RISK
Creators: name: Chen, Gang
name: Roberts, Matthew C.
name: Chen, Gang
name: Roberts, Matthew C.
Publisher: name: Unknown
Year: 2004
Subjects: subject: Marketing
subject: FOS: Economics and business
subject: Risk and Uncertainty

description: Weather conditions pose unique risks to dairy producers. Weather derivatives represent a potentially promising approach to augment dairy producers' risk management against adverse weather events. This study examines the effect of basis risk in weather derivatives, and whether the existence of basis risk mitigates the usefulness of weather derivatives for dairy risk management. Assuming a representative dairy producer has access to both weather derivatives and traditional heat abatement equipment, a closed-form solution for his/her optimal portfolio choice problem in the presence of basis risk is derived within a mean-variance utility framework. First-, second-, and third- degree stochastic dominance criteria are used to test the risk management effectiveness with less restrictive assumptions. Also proportional transaction costs are imposed on weather derivative prices calculated on the basis of actuarial fairness to allow the desirability of these contracts to their issuers.
Disentangled Graph Collaborative Filtering
Creators: name: Wang, Xiang
name: Jin, Hongye
name: Zhang, An
name: He, Xiangnan
name: Xu, Tong
name: Chua, Tat-Seng
Publisher: name: arXiv
Year: 2020
Subjects: subject: Information Retrieval (cs.IR)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: Learning informative representations of users and items from the interaction data is of crucial importance to collaborative filtering (CF). Present embedding functions exploit user-item relationships to enrich the representations, evolving from a single user-item instance to the holistic interaction graph. Nevertheless, they largely model the relationships in a uniform manner, while neglecting the diversity of user intents on adopting the items, which could be to pass time, for interest, or shopping for others like families. Such uniform approach to model user interests easily results in suboptimal representations, failing to model diverse relationships and disentangle user intents in representations. In this work, we pay special attention to user-item relationships at the finer granularity of user intents. We hence devise a new model, Disentangled Graph Collaborative Filtering (DGCF), to disentangle these factors and yield disentangled representations. Specifically, by modeling a distribution over intents for each user-item interaction, we iteratively refine the intent-aware interaction graphs and representations. Meanwhile, we encourage independence of different intents. This leads to disentangled representations, effectively distilling information pertinent to each intent. We conduct extensive experiments on three benchmark datasets, and DGCF achieves significant improvements over several state-of-the-art models like NGCF, DisenGCN, and MacridVAE. Further analyses offer insights into the advantages of DGCF on the disentanglement of user intents and interpretability of representations. Our codes are available in https://github.com/xiangwang1223/disentangled_graph_collaborative_filtering.
description: SIGIR 2020
Electronic Supplementary Material from Phenotypic plasticity of a winter-diapause mechanism copes for the effects of summer global warming in a predator ectotherm
Creators: name: Álvarez, Hugo Alejandro
name: Ruano, Francisca
Publisher: name: The Royal Society
Year: 2024
Subjects: classificationCode: 310399
subject: Ecology not elsewhere classified
classificationCode: 310499
subject: Evolutionary biology not elsewhere classified

description: Additional details of methods and results
Simultaneous X-ray and UV spectroscopy of the Seyfert 1 galaxy NGC 5548.II. Physical conditions in the X-ray absorber
Creators: name: Steenbrugge, K. C.
name: Kaastra, J. S.
name: Crenshaw, D. M.
name: Kraemer, S. B.
name: Arav, N.
name: George, I. M.
name: Liedahl, D. A.
name: van der Meer, R. L. J.
name: Paerels, F. B. S.
name: Turner, T. J.
name: Yaqoob, T.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present the results from a 500 ks Chandra observation of the Seyfert 1 galaxy NGC 5548. We detect broadened emission lines of O VII and C VI in the spectra, similar to those observed in the optical and UV bands. The source was continuously variable, with a 30 % increase in luminosity in the second half of the observation. No variability in the warm absorber was detected between the spectra from the first 170 ks and the second part of the observation. The velocity structure of the X-ray absorber is consistent with the velocity structure measured simultaneously in the ultraviolet spectra. We find that the highest velocity outflow component, at -1040 km/s, becomes increasingly important for higher ionization parameters. This velocity component spans at least three orders of magnitude in ionization parameter, producing both highly ionized X-ray absorption lines (Mg XII, Si XIV) as well as UV absorption lines. A similar conclusion is very probable for the other four velocity components. Based upon our observations, we argue that the warm absorber probably does not manifest itself in the form of photoionized clumps in pressure equilibrium with a surrounding wind. Instead, a model with a continuous distribution of column density versus ionization parameter gives an excellent fit to our data. From the shape of this distribution and the assumption that the mass loss through the wind should be smaller than the accretion rate onto the black hole, we derive upper limits to the solid angle as small as 10^{-4} sr. From this we argue that the outflow occurs in density-stratified streamers. The density stratification across the stream then produces the wide range of ionization parameter observed in this source. Abridged.
description: 21 pages, 12 figures accepted for publication in A&A
On links minimizing the tunnel number
Creators: name: Girão, Darlan
name: Nogueira, João M.
name: Salgueiro, António
Publisher: name: arXiv
Year: 2020
Subjects: subject: Geometric Topology (math.GT)
subject: FOS: Mathematics

description: We show a combinatorial argument in the diagram of large class of links, including satellite and hyperbolic links, where for each of which the tunnel number is the minimum possible, the number of its components minus one.
description: 12 pages, 7 figures
HIDDEN HEALTH COSTS OF PESTICIDE USE IN ZIMBABWE'S SMALLHOLDER COTTON
Creators: name: Maumbe, Blessing M.
name: Swinton, Scott M.
name: Maumbe, Blessing M.
name: Swinton, Scott M.
Publisher: name: Unknown
Year: 2002
Subjects: Crop Production/Industries
Health Economics and Policy

description: Balancing the numerous benefits that may accrue from pesticide use on cotton, farmers face health hazards. Pesticide-induced acute symptoms significantly increased the cost of illness in a survey of 280 smallholder cotton growers in two districts of Zimbabwe. Cotton growers lost a mean of Z$180 in Sanyati and Z$316 per year in Chipinge on pesticide-related direct and indirect acute health effects. These values are equivalent to 45% and 83% of annual household pesticide expenditures in the two districts. The time spent recuperating from illnesses attributed to pesticides averaged 2 days in Sanyati and 4 days in Chipinge during the 1998/99 growing season. These pesticide health cost estimates represent lower bounds only; they omit chronic pesticide health effects as well as suffering and other non-monetary costs. Acute pesticide symptoms were determined in large part by pesticide use practices, notably the lack of protective clothing. Yet many smallholder farmers misunderstood pesticide health hazards, and so did little to protect themselves. Despite the use of simple color codes, 22% of smallholder cotton growers in Sanyati and 58% in Chipinge did not know how to order the four colored pesticide label triangles by toxicity. Better farmer education in exposure averting strategies is needed. Likewise, fuller accounting for hidden health costs in future would allow farmers to make more informed decisions about agricultural pest management.
ESTIMATION OF EFFICIENT REGRESSION MODELS FOR APPLIED AGRICULTURAL ECONOMICS RESEARCH
Creators: name: Ramirez, Octavio A.
name: Misra, Sukant K.
name: Nelson, Jeannie
name: Ramirez, Octavio A.
name: Misra, Sukant K.
name: Nelson, Jeannie
Publisher: name: Unknown
Year: 2002
Subjects: subject: Research Methods/ Statistical Methods
subject: Efficient regression models
subject: partially adaptive estimation
subject: non-normality
subject: skewness
subject: heteroskedasticity
subject: autocorrelation.

description: This paper proposes and explores the use of a partially adaptive estimation technique to improve the reliability of the inferences made from multiple regression models when the dependent variable is not normally distributed. The relevance of this technique for agricultural economics research is evaluated through Monte Carlo simulation and two mainstream applications: A time-series analysis of agricultural commodity prices and an empirical model of the West Texas cotton basis. It is concluded that, given non-normality, this technique can substantially reduce the magnitude of the standard errors of the slope parameter estimators in relation to OLS, GLS and other least squares based estimation procedures, in practice, allowing for more precise inferences about the existence, sign and magnitude of the effects of the independent variables on the dependent variable of interest. In addition, the technique produces confidence intervals for the dependent variable forecasts that are more efficient and consistent with the observed data. Key Words: Efficient regression models, partially adaptive estimation, non-normality, skewness, heteroskedasticity, autocorrelation.
THE LINEAR REGRESSION MODEL WITH AUTOCORRELATED ERRORS: JUST SAY NO TO ERROR AUTOCORRELATION
Creators: name: McGuirk, Anya M.
name: Spanos, Aris
name: McGuirk, Anya M.
name: Spanos, Aris
Publisher: name: Unknown
Year: 2002
Subjects: Research Methods/ Statistical Methods

description: This paper focuses on the practice of serial correlation correcting of the Linear Regression Model (LRM) by modeling the error. Simple Monte Carlo experiments are used to demonstrate the following points regarding this practice. First, the common factor restrictions implicitly imposed on the temporal structure of yt and xt appear to be completely unreasonable for any real world application. Second, when one compares the Autocorrelation-Corrected LRM (ACLRM) model estimates with estimates from the (unrestricted) Dynamic Linear Regression Model (DLRM) encompassing the ACLRM there is no significant gain in efficiency! Third, as expected, when the common factor restrictions do not hold the LRM model gives poor estimates of the true parameters and estimation of the ACLRM simply gives rise to different misleading results! On the other hand, estimates from the DLRM and the corresponding VAR model are very reliable. Fourth, the power of the usual Durbin Watson test (DW) of autocorrelation is much higher when the common factor restrictions do hold than when they do not. But, a more general test of autocorrelation is shown to perform almost as well as the DW when the common factor restrictions do hold and significantly better than the DW when the restrictions do not hold. Fifth, we demonstrate how simple it is to, at least, test the common factor restrictions imposed and we illustrate how powerful this test can be.
MEASUREMENT OF GRADING ERROR COSTS IN THE BEEF INDUSTRY
Creators: name: Ferrier, Peyton Michael
name: Ferrier, Peyton Michael
Publisher: name: Unknown
Year: 2002
Subjects: subject: Marketing
subject: FOS: Economics and business

description: This paper models the market for beef products when quality production is stochastic and quality information is asymmetric between producers and consumers. Independent sorters act as intermediaries to enhance market efficiency by guaranteeing minimum quality levels. Market shares, effort levels, prices, and quality standards are obtained for general market equilibrium.
Chiral Properties of QCD Vacuum in Magnetars- A Nambu-Jona-Lasinio Model with Semi-Classical Approximation
Creators: name: Ghosh, Sutapa
name: Mandal, Soma
name: Chakrabarty, Somenath
Publisher: name: arXiv
Year: 2005
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: The breaking of chiral symmetry of light quarks at zero temperature in presence of strong quantizing magnetic fiels is studied using Nambu-Jona-Lasinio (NJL) model with Thomas-Fermi type semi-classical formalism. It is found that the dynamically generated light quark mass can never become zero if the Landau levels are populated and the mass increases with the increase of magnetic field strength.
description: REVTEX 11 Pages, One .eps figure (included)
Understanding migration drivers: methodology, sensitivity, and heterogeneity
Creators: name: Qi, H.
name: Bircan, T.
Publisher: name: Zenodo
Year: 2021

description: Although fragmented by disciplinary boundaries, most migration theories tend to agree on the importance
 of economic factors in driving the flows of international migration. Nevertheless, empirically, the significance
 of economic factors is not unequivocal, which makes future mobility patterns difficult to foresee with
 certainty. This report seeks to understand what undermines the consistency of empirical findings from a
 methodological perspective. Specifically, we reviewed common approaches for estimating the migration
 responses to economic disparities, and found that the estimates are very sensitive to different model
 assumptions and specifications. We further derived a Flow Specific Common Correlated Effects (FSCCE)
 model. The model estimates revealed pervasive heterogeneity; the economic motives vary substantially
 depending on migrants' countries of origin and their choices of destination in the European Union.
Shock wave propagation in vibrofluidized granular materials
Creators: name: Huang, Kai
name: Miao, Guoqing
name: Zhang, Peng
name: Yun, Yi
name: Wei, Rongjue
Publisher: name: arXiv
Year: 2005
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: Shock wave formation and propagation in two-dimensional granular materials under vertical vibration are studied by digital high speed photography. The steepen density and temperature wave fronts form near the plate as granular layer collides with vibrating plate and propagate upward through the layer. The temperature front is always in the transition region between the upward and downward granular flows. The effects of driving parameters and particle number on the shock are also explored.
description: 9 pages, 4 figures, submitted to PRE
Stakemeier, Eduard: die Konzilskonsitution "über die göttliche Offenbarung"
Creators: name: Küppers, Werner
Publisher: name: Ökumenische Rundschau
Year: 2025

description: Ökumenische Rundschau, Bd. 15 Nr. 4 (1966): Ökumenische Rundschau, Band 15, Heft 4
HI intensity mapping with MeerKAT: 1/f noise analysis
Creators: name: Li, Yichao
name: Santos, Mario G.
name: Grainge, Keith
name: Harper, Stuart
name: Wang, Jingying
Publisher: name: arXiv
Year: 2020
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: The nature of the time correlated noise component (the 1/f noise) of single dish radio telescopes is critical to the detectability of the HI signal in intensity mapping experiments. In this paper, we present the 1/f noise properties of the MeerKAT receiver system using South Celestial Pole (SCP) tracking data. We estimate both the temporal power spectrum density and the 2D power spectrum density for each of the antennas and polarizations. We apply Singular Value Decomposition (SVD) to the dataset and show that, by removing the strongest components, the 1/f noise can be drastically reduced, indicating that it is highly correlated in frequency. Without SVD mode subtraction, the knee frequency over a $20\,$MHz integration is higher than $0.1\,\rm Hz$; with just $2$~mode subtraction, the knee frequency is reduced to $\sim 3\times 10^{-3}\,{\rm Hz}$, indicating that the system induced 1/f-type variations are well under the thermal noise fluctuations over a few hundred seconds time scales. The 2D power spectrum shows that the 1/f-type variations are restricted to a small region in the time-frequency space, either with long wavelength correlations in frequency or in time. This gives a wide range of cosmological scales where the 21cm signal can be measured without further need to calibrate the gain time fluctuations. Finally, we demonstrate that a simple power spectrum parameterization is sufficient to describe the data and provide fitting parameters for both the 1D and 2D power spectrum.
description: 14 pages, 12 figures
ASSESSMENT OF MARKET RISK IN HOG PRODUCTION USING VALUE-AT-RISK AND EXTREME VALUE THEORY
Creators: name: Odening, Martin
name: Hinrichs, Jan
name: Odening, Martin
name: Hinrichs, Jan
Publisher: name: Unknown
Year: 2002
Subjects: Livestock Production/Industries
Risk and Uncertainty

description: The objective of this paper is to investigate the performance of different VaR models in the context of risk assessment in hog production. Potential pitfalls of traditional VaR models are pinpointed and proposals to solve them are analyzed. After a brief description these methods are used to calculate the VaR of the hog finishing margin under German market conditions. In particular we apply Extreme Value Theory (EVT) to our data and compare the results with historical simulation (HS) and the variance-covariance method (VCM). Hill's estimator is used to determine the tail index of the extreme distribution of the gross margin in hog finishing and farrow production. A bootstrap method proposed by Danielsson et al. (1999) is adopted to choose the optimal sample fraction for the tail estimator. It turns out that EVT, VCM, and HS lead to different VaR forecasts if the return distributions are fat tailed and the forecast horizon is long.
Study of the renormalization of BRST invariant local composite operators in the $U(1)$ Higgs model
Creators: name: Capri, M. A. L.
name: Justo, I. F.
name: Palhares, L. F.
name: Peruzzo, G.
name: Sorella, S. P.
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: The renormalization properties of two local BRST invariant composite operators, $(O,V_μ)$, corresponding respectively to the gauge invariant description of the Higgs particle and of the massive gauge vector boson, are scrutinized in the $U(1)$ Higgs model by means of the algebraic renormalization setup. Their renormalization $Z$'s factors are explicitly evaluated at one-loop order in the $\overline{\text{MS}}$ scheme by taking into due account the mixing with other gauge invariant operators. In particular, it turns out that the operator $V_μ$ mixes with the gauge invariant quantity $\partial_νF_{μν}$, which has the same quantum numbers, giving rise to a $2 \times 2$ mixing matrix. Moreover, two additional powerful Ward identities exist which enable us to determine the whole set of $Z$'s factors entering the $2 \times 2$ mixing matrix as well as the $Z$ factor of the operator $O$ in a purely algebraic way. An explicit check of these Ward identities is provided. The final setup obtained allows for computing perturbatively the full renormalized result for any $n$-point correlation function of the scalar and vector composite operators.
description: 36 pages, 6 figures
PopII 1/2 stars: very high N14 and low O16 yields
Creators: name: Hirschi, Raphael
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Nine 20 Mo models were computed with metallicities ranging from solar, through $Z=10^{-5}$ ([Fe/H]=~-3.1) down to $Z=10^{-8}$ ([Fe/H]=~-6.1) and with initial rotational velocities between 0 and 600 km/s to study the impact of initial metallicity and rotational velocity. The very large amounts of N14 observed (~0.03 Mo) are only produced at $Z=10^{-8}$ (PopII 1/2). The strong dependence of the N14 yields on rotation and other parameters like the initial mass and metallicity may explain the large scatter in the observations of N14 abundance. The metallicity trends are best reproduced by the models with Omega_ini/Omega_c=~0.75, which is slightly above the mean observed value for OB solar metallicity stars. Indeed, in the model with Vini=600 km/s at $Z=10^{-8}$, the O16 yield is reduced due to strong mixing. This allows in particular to reproduce the upturn for C/O and a slightly decreasing [C/Fe], which are observed below [Fe/H]=~-3.
description: 2 pages, Conf. Proceedings: From Lithium to Uranium: Elemental Tracers of Early Cosmic Evolution, June 2005, Eds.:V. Hill, P. Fran\c{c}ois and F. Primas
Usmon Ibn Affon hayotlari va fazilatlari
Creators: name: Axmatov Shoxrux, Toshkent axborot texnologiyalari  universiteti Samarqand filiali AX23-08 guruh talabasi
name: Ilmiy rahbar: X.U.Samatov
Publisher: name: Zenodo
Year: 2024

description: Ushbu  maqolada  xulafoi  roshidinlarning  uchinchi,  jannat bashorati  berilgan  o‘n  sahobiyning  biri,  ilk  mususlmon  bo’lganlardan  va Zunnurayn  -  ikki  nursohibi  -  Usmon  ibn  Affonning  hayotlari  va  fazilatlari  aks ettirilgan.
Η αυξανόμενη σημασία της διεθνούς μετανάστευσης για τις μεταβολές του συνολικού πληθυσμού στην Ελλάδα και την Ευρωπαϊκή Ένωση των 27 Κρατών Μελών (The growing importance of international migration for the changes of the total population in Greece and the European Union of 27 Member States (2014-2019) )
Creators: name: BAGAVOS, CHRISTOS
Publisher: name: figshare
Year: 2021
Subjects: subject: 160399 Demography not elsewhere classified
subject: FOS: Sociology

description: The growing importance of international migration as a component of recent and expected changes in the overall population as well as the contribution of migrants to the average fertility of host countries are two important aspects of the demographic landscape in European countries. The following text analyzes the distinct role of immigrants and natives for the recent changes in the total population in Greece and the European Union of 27 Member States

Η διευρυμένη σημασία της διεθνούς μετανάστευσης ως συνιστώσας των πρόσφατων αλλά και των αναμενόμενων μεταβολών του συνολικού πληθυσμού καθώς και η συμβολή των μεταναστών στη μέση γονιμότητα των χωρών υποδοχής αποτελούν δύο σημαντικές πτυχές του δημογραφικού τοπίου στις χώρες της Ευρώπης. Στο κείμενο που ακολουθεί αναλύεται ο διακριτός ρόλος των μεταναστών και των γηγενών για τις πρόσφατες μεταβολές του συνολικού πληθυσμού στην Ελλάδα και την Ευρωπαϊκή Ένωση των 27 Κρατών Μελών. Η χώρα γέννησης χρησιμοποιείται ως κριτήριο για τον προσδιορισμό της μετανάστευσης. Έτσι ο όρος μετανάστες αναφέρεται στα άτομα που δεν έχουν γεννηθεί στη χώρα αναφοράς και ο όρος γηγενείς, αν και παραπέμπει στο γένος, χρησιμοποιείται για τα άτομα που έχουν γεννηθεί στη χώρα αναφοράς (εναλλακτικά θα μπορούσαν να χρησιμοποιηθούν οι όροι ετερόχθονες και αυτόχθονες).
Point process model of 1/f noise versus a sum of Lorentzians
Creators: name: Kaulakys, B.
name: Gontis, V.
name: Alaburda, M.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Astrophysics (astro-ph)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Computational Engineering, Finance, and Science (cs.CE)
subject: Statistics Theory (math.ST)
subject: Adaptation and Self-Organizing Systems (nlin.AO)
subject: Data Analysis, Statistics and Probability (physics.data-an)
subject: Neurons and Cognition (q-bio.NC)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences
subject: FOS: Mathematics
subject: FOS: Biological sciences

description: We present a simple point process model of $1/f^β$ noise, covering different values of the exponent $β$. The signal of the model consists of pulses or events. The interpulse, interevent, interarrival, recurrence or waiting times of the signal are described by the general Langevin equation with the multiplicative noise and stochastically diffuse in some interval resulting in the power-law distribution. Our model is free from the requirement of a wide distribution of relaxation times and from the power-law forms of the pulses. It contains only one relaxation rate and yields $1/f^ β$ spectra in a wide range of frequency. We obtain explicit expressions for the power spectra and present numerical illustrations of the model. Further we analyze the relation of the point process model of $1/f$ noise with the Bernamont-Surdin-McWhorter model, representing the signals as a sum of the uncorrelated components. We show that the point process model is complementary to the model based on the sum of signals with a wide-range distribution of the relaxation times. In contrast to the Gaussian distribution of the signal intensity of the sum of the uncorrelated components, the point process exhibits asymptotically a power-law distribution of the signal intensity. The developed multiplicative point process model of $1/f^β$ noise may be used for modeling and analysis of stochastic processes in different systems with the power-law distribution of the intensity of pulsing signals.
description: 23 pages, 10 figures, to be published in Phys. Rev. E
PRODUCTION AND FINANCIAL IMPACTS OF THE ADOPTION OF BOVINE SOMATOTROPIN ON U.S. DAIRY FARMS
Creators: name: McBride, William D.
name: Short, Sara D.
name: El-Osta, Hisham S.
name: McBride, William D.
name: Short, Sara D.
name: El-Osta, Hisham S.
Publisher: name: Unknown
Year: 2002
Subjects: Livestock Production/Industries

description: Production and financial impacts of recombinant bovine somatotropin (rbST) adoption are assessed using a survey of U.S. dairy operations and a model that corrects for self-selection bias. A substantial increase in milk production per cow is associated with rbST adoption, but large estimated financial impacts are not statistically significant. Substantial variation in the net returns of rbST adopters may be related to the management-intensive nature of rbST.
THE ECONOMICS OF FLOW ENHANCEMENT VS. NUTRIENT CONTROLS IN MEETING WATER QUALITY STANDARDS
Creators: name: Keeler, Andrew G.
name: Marbury, Leslie
name: Keeler, Andrew G.
name: Marbury, Leslie
Publisher: name: Unknown
Year: 2004
Subjects: Environmental Economics and Policy

description: This paper explores the economics of using enhanced flow as part of a strategy to meet water quality standards. We begin by briefly sketching the relevant economic theory, which we then apply to a case study of a dissolved oxygen impaired stream segment in Georgia's Flint River Basin. Results show that meeting targeted water quality standards with strategies that include enhanced flow is significantly less costly than relying only on agricultural management practices.
POLICIES TO REDUCE FOREST FRAGMENTATION: COMBINING ECONOMETRIC MODELS WITH GIS-BASED LANDSCAPE SIMULATIONS
Creators: name: Lewis, David J.
name: Plantinga, Andrew J.
name: Lewis, David J.
name: Plantinga, Andrew J.
Publisher: name: Unknown
Year: 2004
Subjects: Resource /Energy Economics and Policy

description: Forest fragmentation is a primary threat to terrestrial biodiversity. We combine a parcel-level econometric model of land-use transitions with spatially-explicit landscape simulations to predict the empirical distribution of fragmentation outcomes under given market conditions and policy scenarios. Our model explains transitions between forest, agricultural, and urban uses, allowing us to model land use change in both rural and urban areas. A Monte Carlo simulation approach links econometrically-derived transition probabilities to GIS maps for the prediction of the spatial properties of habitat change.