cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Photometric detection of internal gravity waves in upper main-sequence stars. II. Combined TESS photometry and high-resolution spectroscopy
Creators: name: Bowman, D. M.
name: Burssens, S.
name: Simón-Díaz, S.
name: Edelmann, P. V. F.
name: Rogers, T. M.
name: Horst, L.
name: Roepke, F. K.
name: Aerts, C.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Context. Massive stars are predicted to excite internal gravity waves (IGWs) by turbulent core convection and from turbulent pressure fluctuations in their near-surface layers. These IGWs are extremely efficient at transporting angular momentum and chemical species within stellar interiors, but they remain largely unconstrained observationally. Aims. We aim to characterise the photometric detection of IGWs across a large number of O and early-B stars in the Hertzsprung-Russell diagram, and explain the ubiquitous detection of stochastic variability in the photospheres of massive stars. Methods. We combined high-precision time-series photometry from the NASA Transiting Exoplanet Survey Satellite with high-resolution ground-based spectroscopy of 70 stars with spectral types O and B to probe the relationship between the photometric signatures of IGWs and parameters such as spectroscopic mass, luminosity, and macroturbulence. Results. A relationship is found between the location of a star in the spectroscopic Hertzsprung-Russell diagram and the amplitudes and frequencies of stochastic photometric variability in the light curves of massive stars. Furthermore, the properties of the stochastic variability are statistically correlated with macroturbulent velocity broadening in the spectral lines of massive stars. Conclusions. The common ensemble morphology for the stochastic low-frequency variability detected in space photometry and its relationship to macroturbulence is strong evidence for IGWs in massive stars, since these types of waves are unique in providing the dominant tangential velocity field required to explain the observed spectroscopy.
description: Accepted for publication in A&A. 10 pages and 5 figures (and an additional 7 pages of appendix tables and figures). Resolution of appendix figures have been downgraded to meet arXiv's maximum file size of 15Mb. This version (2ver) is post A&A language editing
Finite-size scaling exponents and entanglement in the two-level BCS model
Creators: name: Dusuel, S.
name: Vidal, J.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Nuclear Theory (nucl-th)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We analyze the finite-size properties of the two-level BCS model. Using the continuous unitary transformation technique, we show that nontrivial scaling exponents arise at the quantum critical point for various observables such as the magnetization or the spin-spin correlation functions. We also discuss the entanglement properties of the ground state through the concurrence which appears to be singular at the transition.
description: 4 pages, 3 figures, published version
Forward-backward multiplicity and momentum correlations in $pp$ collisions at LHC energies
Creators: name: Mondal, Mitali
name: Mondal, Joyati
name: Kar, Somnath
name: Deb, Argha
name: Ghosh, Premomoy
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Charged-particle multiplicity and summed values of the transverse momentum ($p_{\rm T}$) have been utilized for estimating forward-backward (FB) correlation strength for EPOS3 simulated proton-proton ($pp$) events with and without hydrodynamical evolution of particles at center-of-mass energies $\sqrt{s}$ = 0.9, 2.76, and 7 TeV for different pseudorapidity window width ($δη$) and gap ($η_{gap}$) between the FB windows. We have studied the variation of FB correlation strength with $η_{gap}$, $δη$, $\sqrt{s}$, $p_{\rm T}$ cuts and multiplicity classes. Results are compared with the corresponding ALICE and ATLAS data. EPOS3 model qualitatively reproduces the overall variation of correlation strength of the LHC data. However, quantitative agreement is better for $pp$ events, generated using EPOS3 with hydrodynamical evolution of particles, with ATLAS data.
description: 11 pages, 15 figures
Determinants of Food Choice in a Transitional Economy: Insights from the Theory of Reasoned Action
Creators: name: Petrovici, Dan Alex
name: Ritson, Christopher
name: Ness, M.
name: Petrovici, Dan Alex
name: Ritson, Christopher
name: Ness, M.
Publisher: name: Unknown
Year: 2002
Subjects: subject: Consumer/Household Economics
subject: Theory of Reasoned Action
subject: food choice
subject: transition economy

description: This paper draws upon a consumer survey carried out in Bucharest (Romania) to explore determinants of food choice in a transition economy. An adapted version of the Theory of Reasoned Action was developed. This included attitude toward intention, habit and preference as independent variables. The structural equations modelling carried out in 'Analysis of MOment Structures' AMOS showed a significant positive influence of all variables. Similar to other studies conducted in European Union (EU) countries (Saba, Di Natale, 1998) habit outweighed the other variables. The study emphasises the heterogeneity of consumer beliefs about food. Furthermore it was suggested that there is scope for noneconomic variables in explaining food choices and consumer behaviour in these emerging economies, though the influence of these variables may be still limited relative the economic factors. Further research on special groups is required to quantify the influence of non-economic factors and compare the results estimated in Romania with other countries which are candidates to EU accession.
Investment, and Contract Hold-Ups in Transition: Evidence from Hungary
Creators: name: Gow, Hamish R.
name: Swinnen, Johan F.M.
name: Gow, Hamish R.
name: Swinnen, Johan F.M.
Publisher: name: Unknown
Year: 2002
Subjects: subject: Agricultural Finance
subject: contracting
subject: hold-ups
subject: firm investment
subject: transition

description: This paper analyses empirically the effect of "hold-ups" on capital investment in farms using a sample of 318 Hungarian enterprises, surveyed over 1997. A negative relationship arises between capital investment and the incidence of hold-up behaviour. This relationship is affected by farm's wealth and liquidity position, the quality of legal enforcement of contracts, by whether farms have contracted sales to foreign processors, and whether they are established as successors to pre-reform organisations rather than start-up businesses.
Are Farmers Completely Rational Consumers and Do They Suffer from a Borrowing Constraint? The Dutch Case
Creators: name: Woldehanna, Tassew
name: Oskam, Arie J.
name: Woldehanna, Tassew
name: Oskam, Arie J.
Publisher: name: Unknown
Year: 2002
Subjects: subject: Farm Management
subject: consumption
subject: Euler equation
subject: borrowing constraint
subject: Dutch farm households

description: There is some confusion in the literature on the consumption behaviour of farmers. We try to clear up some of the issues surrounding this confusion by elaborating and testing a model. Euler equations have been derived from a constant relative risk aversion utility function for total consumption expenditure, household expenditure and other expenditure, which includes durable goods. According to a test of Euler equations, farm households are not simply optimising lifetime utility. Rather, these households follow simple consumption rules, strongly influenced by habit formation. In line with most of the literature, we find that farm households are not borrowing constrained in their consumption expenditures.
Low Carbon Abundance in Type Ia Supernovae
Creators: name: Marion, G. H.
name: Hoeflich, P.
name: Wheeler, J. C.
name: Robinson, E. L.
name: Gerardy, C. L.
name: Vacca, W. D.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We investigate the quantity and composition of unburned material in the outer layers of three normal Type Ia supernovae (SNe Ia): 2000dn, 2002cr and 20 04bw. Pristine matter from a white dwarf progenitor is expected to be a mixture of oxygen and carbon in approximately equal abundance. Using near-infrared (NIR, 0.7-2.5 microns) spectra, we find that oxygen is abundant while carbon is severely depleted with low upper limits in the outer third of the ejected mass. Strong features from the OI line at rest wavelength = 0.7773 microns are observed through a wide range of expansion velocities approx. 9,000 - 18,000 km/s. This large velocity domain corresponds to a physical region of the supernova with a large radial depth. We show that the ionization of C and O will be substantially the same in this region. CI lines in the NIR are expected to be 7-50 times stronger than those from OI but there is only marginal evidence of CI in the spectra and none of CII. We deduce that for these three normal SNe Ia, oxygen is more abundant than carbon by factors of 100 - 1,000. MgII is also detected in a velocity range similar to that of OI. The presence of O and Mg combined with the absence of C indicates that for these SNe Ia, nuclear burning has reached all but the extreme outer layers; any unburned material must have expansion velocities greater than 18,000 km/s. This result favors deflagration to detonation transition (DD) models over pure deflagration models for SNe Ia.
description: accepted for publication in ApJ
Parametric probabilistic approach for cumulative fatigue damage using double linear damage rule considering limited data
Creators: name: Dias, João Paulo
name: Ekwaro-Osire, Stephen
name: Cunha, Americo
name: Dabetwar, Shweta
name: Nispel, Abraham
name: Alemayehu, Fisseha M.
name: Endeshaw, Haileyesus B.
Publisher: name: arXiv
Year: 2024
Subjects: subject: Computational Engineering, Finance, and Science (cs.CE)
subject: FOS: Computer and information sciences
subject: I.6.6
subject: 82D35

description: This work proposes a parametric probabilistic approach to model damage accumulation using the double linear damage rule (DLDR) considering the existence of limited experimental fatigue data. A probabilistic version of DLDR is developed in which the joint distribution of the knee-point coordinates is obtained as a function of the joint distribution of the DLDR model input parameters. Considering information extracted from experiments containing a limited number of data points, an uncertainty quantification framework based on the Maximum Entropy Principle and Monte Carlo simulations is proposed to determine the distribution of fatigue life. The proposed approach is validated using fatigue life experiments available in the literature.
Influence of Political Campaign Contributions by American Agribusiness Firms on U.S. Farm Policy
Creators: name: Serrao, Amilcar
name: Serrao, Amilcar
Publisher: name: Unknown
Year: 2002
Subjects: subject: Political Economy
subject: Agribusiness firm
subject: farm policy
subject: lobbying
subject: political contributions

description: This study adapts Ndayisenga and Kinsey's econometric model of the allocation of political campaign contributions by agribusiness firms. This model combines information on campaign contributions for political influence with the behavior assumption of profit maximization to test the hypotheses that agribusiness firms do not lobby against farm policies. Model results support the hypotheses and show that lobbying expenditure in output markets is statistically significant, and that political campaign contributions to the Democratic Party significantly correlate with agribusiness firms' profits. The conclusions of this study provide useful information about the intentions of agribusiness firms that participate in the political market, but the results should be carefully interpreted.
XMM-Newton observations of four millisecond pulsars
Creators: name: Zavlin, Vyacheslav E.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: I present an analysis of the XMM-Newton observations of four millisecond pulsars, J0437-4715, J2124-3358, J1024-0719, and J0034-0534. The new data provide strong evidence of thermal emission in the X-ray flux detected from the first three objects. This thermal component is best interpreted as radiation from pulsar polar caps covered with a nonmagnetic hydrogen atmosphere. A nonthermal power-law component, dominating at energies E>3 keV, can also be present in the detected X-ray emission. For PSR J0437-4715, the timing analysis reveals that the shape and pulsed fraction of the pulsar light curves are energy dependent. This, together with the results obtained from the phase-resolved spectroscopy, supports the two-component (thermal plus nonthermal) interpretation of the pulsar's X-ray radiation. Highly significant pulsations have been found in the X-ray flux of PSRs J2124-3358 and J1024-0719. For PSR J0034-0534, a possible X-ray counterpart of the radio pulsar has been suggested. The inferred properties of the detected thermal emission are compared with predictions of radio pulsar models.
description: 33 pages, 13 figures (of them 4 are color); to be published in ApJ
Gigahertz phononic integrated circuits on thin-film lithium niobate on sapphire
Creators: name: Mayor, Felix M.
name: Jiang, Wentao
name: Sarabalis, Christopher J.
name: McKenna, Timothy P.
name: Witmer, Jeremy D.
name: Safavi-Naeini, Amir H.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Applied Physics (physics.app-ph)
subject: Optics (physics.optics)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Acoustic devices play an important role in classical information processing. The slower speed and lower losses of mechanical waves enable compact and efficient elements for delaying, filtering, and storing of electric signals at radio and microwave frequencies. Discovering ways of better controlling the propagation of phonons on a chip is an important step towards enabling larger scale phononic circuits and systems. We present a platform, inspired by decades of advances in integrated photonics, that utilizes the strong piezoelectric effect in a thin film of lithium niobate on sapphire to excite guided acoustic waves immune from leakage into the bulk due to the phononic analogue of index-guiding. We demonstrate an efficient transducer matched to 50 ohm and guiding within a 1-micron wide mechanical waveguide as key building blocks of this platform. Putting these components together, we realize acoustic delay lines, racetrack resonators, and meander line waveguides for sensing applications. To evaluate the promise of this platform for emerging quantum technologies, we characterize losses at low temperature and measure quality factors on the order of 50,000 at 4 kelvin. Finally, we demonstrate phononic four-wave mixing in these circuits and measure the nonlinear coefficients to provide estimates of the power needed for relevant parametric processes.
description: 15 pages,12 figures, the first two authors contributed equally
Territorial Product Associations in Greece: The Case of Olive Oil
Creators: name: Philippidis, George
name: Kakaroglou, Ioannis
name: Sanjuan, Ana Isabel
name: Philippidis, George
name: Kakaroglou, Ioannis
name: Sanjuan, Ana Isabel
Publisher: name: Unknown
Year: 2002
Subjects: Agribusiness

description: The change in emphasis of European food policy toward legislative certification schemes has shifted the research agenda toward investigating the link between the concept of 'territory' and food product perceptions. However, a relatively neglected aspect of this literature is the exploratory qualitative work investigating consumer perceptions of 'symbolic' attributes within territorial products. More importantly, there is a dearth of equivalent research subjecting these exploratory findings to rigorous quantitative analysis. Accordingly, this paper addresses this weakness in the literature examining the perceptual inter-relationships between a broad range of intrinsic, extrinsic and symbolic cues by deriving underlying product dimensions. Consumer segments based on these product dimensions are derived and profiled using an array of socio-economic, lifestyle and product knowledge variables. Finally, marketing policy conclusions are drawn.
Productive Efficiency in Agriculture: Corn Production in Mexico
Creators: name: Yunez-Naude, Antonio
name: Juarez-Torres, Miriam
name: Barceinas-Paredes, Fernando
name: Yunez-Naude, Antonio
name: Juarez-Torres, Miriam
name: Barceinas-Paredes, Fernando
Publisher: name: Unknown
Year: 2006
Subjects: Crop Production/Industries
Productivity Analysis

description: Using a stochastic production frontier model and data for 2002 from a representative sample of Mexican rural households, in this paper we first study empirically whether or not small and medium farmers produce corn efficiently. The results show that corn production is inefficient, nation-wide and for both commercial and subsistence farmers. Our findings also show that this is even more so for subsistence producers and for the Center and the South-southeast regions of rural Mexico. In addition, we find that subsistence farmers use less prod uctive inputs (seeds and agrochemicals) with respect to commercial farmers. Based on these results, we then apply a regression model to inquire about the factors explaining inefficiency. We get that farmers facing natural disasters, that produce corn for subsistence using diverse seed varieties of the grain in plots with less than 1 hectare and indigenous, are more inefficient than other farmers. The results also indicate that households located in communities with marketing facilities and that have benefited from infrastructural investments, produce corn in a less inefficient manner. The detailed nature of the data used allows us to have results that differentiate rural regions as well as commercial and subsistence corn producers, and hence, to suggest focalized policies for rural development.
On the solvability of bipolar max-product fuzzy relation equations with the product negation
Creators: name: Cornejo, M. Eugenia
name: Lobo, David
name: Medina, Jesús
Publisher: name: arXiv
Year: 2024
Subjects: subject: General Mathematics (math.GM)
subject: FOS: Mathematics

description: This paper studies the solvability of the max-product fuzzy relation equations in which a negation operator is considered. Specifically, the residuated negation of the product t-norm has been introduced in these equations in order to increase the flexibility of the standard fuzzy relation equations introduced by Sanchez in 1976. The solvability and the set of solutions of these bipolar equations have been studied in different scenarios, depending on the considered number of variables and equations.
Análise dos fatores determinantes para o decreto de prisão preventiva em casos envolvendo acusações por roubo, tráfico de drogas e furto: Um estudo no âmbito das cidades mais populosas do Paraná
Creators: name: Policeno, Giovane Cerezuela
name: da Silva, Mario Edson Passerino Fischer
name: Ostrensky, Vitor Pestana
Publisher: name: arXiv
Year: 2020
Subjects: subject: General Economics (econ.GN)
subject: FOS: Economics and business

description: Based on the theoretical assumptions of the Labeling Approach, Critical Criminology and Behavioral Economics, taking into account that almost half of the Brazilian prison population is composed of individuals who are serving pre-trial detention, it was sought to assess the characteristics of the flagranteated were presented as determinants to influence the subjectivity of the judges in the decision to determine, or not, the custody of these. The research initially adopted a deductive methodology, based on the principle that external objective factors encourage magistrates to decide in a certain sense. It was then focused on the identification of which characteristics of the flagranteated and allegedly committed crimes would be relevant to guide such decisions. Subsequently, after deduction of such factors, an inductive methodology was adopted, analyzing the data from the theoretical assumptions pointed out. During the research, 277 decisions were analyzed, considering decision as individual decision and not custody hearing. This sample embarked decisions of six judges among the largest cities of the State of Paraná and concerning the crimes of theft, robbery and drug trafficking. It was then concluded that the age, gender, social class and type of accusation that the flagranteated suffered are decisive for the decree of his provisional arrest, being that, depending on the judge competent in the case, the chances of the decree can increase in Up to 700%, taking into account that the circumstantial and causal variables are constant. Given the small sample size, as far as the number of judges is concerned, more extensive research is needed so that conclusions of national validity can be developed.
description: 23 pages, in Portuguese
Convex domains and K-spectral sets
Creators: name: Badea, Catalin
name: Crouzeix, Michel
name: Delyon, Bernard
Publisher: name: arXiv
Year: 2005
Subjects: subject: Functional Analysis (math.FA)
subject: Operator Algebras (math.OA)
subject: FOS: Mathematics
subject: 47A12

description: Let $Ω$ be an open convex domain of the complex plane. We study constants K such that $Ω$ is K-spectral or complete K-spectral for each continuous linear Hilbert space operator with numerical range included in $Ω$. Several approaches are discussed.
description: the introduction was changed and some remarks have been added. 26 pages ; to appear in Math. Z
Exploring Environmental-Economic Benefits from Agri-Industrial Diversification in the Sugar Industry: An Integrated Land Use and Value Chain Approach
Creators: name: Roebeling, Peter C.
name: Smith, D. Mark
name: Van Grieken, Martijn
name: Roebeling, Peter C.
name: Smith, D. Mark
name: Van Grieken, Martijn
Publisher: name: Unknown
Year: 2006
Subjects: subject: Environmental Economics and Policy
subject: Land Economics/Use
subject: spatial economics
subject: environmental economics
subject: value chains
subject: agri-industries
subject: water quality

description: The sugar industry in Queensland (Australia) is confronted with increasing economic pressure and environmental constraints. To explore whether agri-industrial diversification of the sugar industry provides a sustainable development pathway for the region, we develop a spatial environmental-economic approach that integrates a land use and value chain model with a hydrological model. Results indicate that agri-industrial diversification can lead to substantial increases in regional income, while at the same time increasing the resilience of a sugar industry facing decreasing sugar prices. Agri-industrial diversification drives land use diversification, which under current sugar prices does not lead to a reduction in sugarcane production. Water quality benefits from this land use diversification are mixed, and depend on the economic viability and erosion characteristics of the concerned production systems.
title: Alabama Charter School Parent Voice
Creators: name: Schoettler, Natalie
name: Marshall, David
Publisher: name: Plains Research Consortium
Year: 2025
Subjects: charter schools
enrollment decision-making
satisfaction
responsiveness
inclusion

description: In 2015, Alabama became the 43rd state to establish charter schools as part of their public education system. To better understand if Alabama charter schools meet their objectives, we conducted a survey (and subsequent focus groups) of 460 parents across six Alabama charter schools during the 2023-24 school year. By large margins, parents expressed high satisfaction with their child’s school. Moreover, 87% indicated they would re-enroll their child at their school, and the same proportion gave their school a letter grade of A or B. Parents across all racial and special education groups similarly agreed that their child’s school leader and teachers were responsive and that their school was inclusive of all students.
Agriculturally Related Environmental Issues in Free Trade Agreements
Creators: name: Colyer, Dale
name: Colyer, Dale
Publisher: name: Unknown
Year: 2006
Subjects: subject: Environmental Economics and Policy
subject: International Relations/Trade
subject: trade and environment
subject: agricultural trade
subject: trade liberalization
subject: Doha Round

description: The consideration of environmental matters in trade liberalization agreements has become an issue since they were included in NAFTA and recognized Uruguay round agreement that created the WTO. Many WTO members, especially the less developed countries, remain opposed to including environmental issues in trade agreements. However, Canada, the U.S. and a few other countries now include environmental provisions in their bilateral and regional trade agreements; the U.S. is required to do so under its 2002 Trade Promotion Act (PL 107-210). Furthermore, the declaration establishing the Doha Round of multilateral negotiations recognizes a role, albeit a limited one, for the environment in negotiating the next multilateral trade liberalization agreement. Negotiations on these issues have been intense with relatively little agreed on to date.
Vulnerability and Risk Management among Turkmen Leaseholders
Creators: name: Glukhikh, Rimma
name: Lerman, Zvi
name: Schwartz, Moshe
name: Glukhikh, Rimma
name: Lerman, Zvi
name: Schwartz, Moshe
Publisher: name: Unknown
Year: 2006
Subjects: subject: Risk and Uncertainty
subject: agriculture
subject: Turkmenistan
subject: transition
subject: vulnerability
subject: income smoothing

description: High risk is inherent to agriculture in Turkmenistan, a post-socialist desert country where the political uncertainties of transition exacerbate natural unpredictability. This study examines risk coping strategies of Turkmen farmers based on a survey of 1100 respondents carried out in 2002 in all five provinces. We propose a new composite index of vulnerability, which includes human capital indicators and geographic location. The analysis relies on a single independent variable, which nevertheless incorporates the effect of criteria interactions. Using survey data, we analyze income smoothing as a mechanisms of risk management across vulnerability groups. Consistently with theoretical expectations, the most vulnerable households seem prefer a smaller, but safer outcome over a larger but uncertain one: the most vulnerable households tend to specialize in wheat, which is less risky (and less profitable) than cotton, while less vulnerable households emphasize cotton. However, contrary to expectations and findings in other countries, Turkmen farmers do not follow many of the common risk coping strategies. The more vulnerable households do not readily diversify their income generating activities: they seldom take off-farm employment; rarely engage in cottage industries; do not diversify the production mix on their household plot. Nor is there evidence that the more vulnerable families show greater reliance on their subsistence household plot. The results seem to suggest that the more vulnerable households are trapped in a deep vulnerability trap, lacking initiative and probably resources to break out through income diversification strategies.
Marginal Intra-Industry Trade and Adjustment Costs in the Hungarian Food Industry
Creators: name: Ferto, Imre
name: Ferto, Imre
Publisher: name: Unknown
Year: 2006
Subjects: subject: Marketing
subject: FOS: Economics and business
subject: intra-industry trade
subject: adjustment costs
subject: food industry

description: Recent developments in intra-industry trade (IIT) literature focus on the relationships between IIT and adjustment costs associated with changes in trade pattern. The effects of trade liberalisation depend, inter alia, on whether trade is of an inter-industry or intra-industry nature. The belief that IIT leads to lower costs of factor market adjustment, particularly for labour, gives rise to the smooth-adjustment hypothesis Hungarian agricultural trade was liberalised via WTO agreement and some regional trade integration agreement (Association Agreement, CEFTA). It is reasonable assume that these partial trade liberalisation should have an effect on trade pattern and employment changes. The aim of the paper is to identify the effects of partial trade liberalisation on adjustment costs in Hungarian food industry employing recent developments in the IIT literature. The structure of Hungary's food trade expansion over the transition period 1992-2002 and its implications for labour-market adjustment is examined. An econometric analysis of trade and employment data suggests that changes in domestic consumption and productivity have significant influence on employment changes. But our results do not provide support for the smooth-adjustment hypo thesis of intraindustry trade.
Partly divisible probability measures on locally compact Abelian groups
Creators: name: Albeverio, S.
name: Gottschalk, H.
name: Wu, J. -L.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Probability (math.PR)
subject: FOS: Mathematics
subject: 60B15, 60E10

description: A notion of admissible probability measures $μ$ on a locally compact Abelian group (LCA-group) $G$ with connected dual group $\hat G=\R^d\times \T^n$ is defined. To such a measure $μ$, a closed semigroup $Λ(μ)\subseteq (0,\infty)$ can be associated, such that, for $t\in Λ(μ)$, the Fourier transform to the power $t$, $(\hat μ)^t$, is a characteristic function. We prove that the existence of roots for non admissible probability measures underlies some restrictions, which do not hold in the admissible case. As we show for the example $\Z_2$, in the case of LCA-groups with non connected dual group, there is no canonical definition of the set $Λ(μ)$.
description: 15 pages
Kenyan Supermarkets and Horticultural Farm Sector Development
Creators: name: Neven, David
name: Reardon, Thomas
name: Neven, David
name: Reardon, Thomas
Publisher: name: Unknown
Year: 2006
Subjects: subject: Marketing
subject: FOS: Economics and business
subject: supermarkets
subject: development
subject: hor ticulture
subject: farm technology
subject: Africa

description: In Kenya, supermarkets have grown from a tiny n iche at the start of the 1990s to 20% of the urban food retail sector in 2003. Furthermore, Kenyan supermarket chains are increasingly sourcing from global markets and have started to expand their store network in the wider East Africa region. Within this context, this study focused on the farm-level response to the rise of supermarkets and the new challenges and opportun ities they create. The research found that the rise of supermarkets in Kenya has given rise to a new group of medium-sized farms managed by well-educated farmers. Focusing on kale, the research shows that nearly all supermarket-channel farmers have the capacity to supply larger volumes year round and have transportation vehicles, an irrigation system, a packing shed, a cellular phone, and so on, po inting to the existence of a threshold capital vector which farmers must have in order to access supermarkets. Kale suppliers to supermarkets use more capital intensive production technologies, leading to average labor and land productivities which are 60-70% higher than in the traditional channel. While most traditional-channel kale farmers sell to brokers and get a price that lets them break-even at best, supermarket-channel farmers have a 40% gross profit margin. These margins and lower market risks in the supermarket channel have resulted in a strong growth dynamic of supermarket-channel farmers which have doubled the size of their operations over the last five years.
An analytical comprehensive solution for the superficial waves appearing in gravity-driven flows of liquid films
Creators: name: Chimetta, Bruno Pelisson
name: Franklin, Erick de Moraes
Publisher: name: arXiv
Year: 2020
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences
subject: 76E17

description: This paper is devoted to analytical solutions for the base flow and temporal stability of a liquid film driven by gravity over an inclined plane when the fluid rheology is given by the Carreau-Yasuda model, a general description that applies to different types of fluids. In order to obtain the base state and critical conditions for the onset of instabilities, two sets of asymptotic expansions are proposed, from which it is possible to find four new equations describing the reference flow and the phase speed and growth rate of instabilities. These results lead to an equation for the critical Reynolds number, which dictates the conditions for the onset of the instabilities of a falling film. Different from previous works, this paper presents asymptotic solutions for the growth rate, wavelength and celerity of instabilities obtained without supposing a priori the exact fluid rheology, being, therefore, valid for different kinds of fluids. Our findings represent a significant step toward understanding the stability of gravitational flows of non-Newtonian fluids.
description: This is a pre-print of an article published in Zeitschrift f\"{u}r angewandte Mathematik und Physik, 71, 122(2020). The final authenticated version is available online at: https://doi.org/10.1007/s00033-020-01349-x
The Kadison-Singer Problem in Mathematics and Engineering
Creators: name: Casazza, Peter G.
name: Fickus, Matt
name: Tremain, Janet C.
name: Weber, Eric
Publisher: name: arXiv
Year: 2005
Subjects: subject: Functional Analysis (math.FA)
subject: FOS: Mathematics
subject: 42C15; 46B03; 46C05; 47A05; 46L05; 46L10

description: We will show that the famous, intractible 1959 Kadison-Singer problem in $C^{*}$-algebras is equivalent to fundamental unsolved problems in a dozen areas of research in pure mathematics, applied mathematics and Engineering. This gives all these areas common ground on which to interact as well as explaining why each of these areas has volumes of literature on their respective problems without a satisfactory resolution. In each of these areas we will reduce the problem to the minimum which needs to be proved to solve their version of Kadison-Singer. In some areas we will prove what we believe will be the strongest results ever available in the case that Kadison-Singer fails. Finally, we will give some directions for constructing a counter-example to Kadison-Singer.
SPEAR Far Ultraviolet Spectral Images of the Cygnus Loop
Creators: name: Seon, Kwang-Il
name: Han, Wonyong
name: Nam, Uk-Won
name: Park, Jang-Hyun
name: Edelstein, Jerry
name: Korpela, Eric J.
name: Sankrit, Ravi
name: Min, Kyoung-Wook
name: Ryu, Kwangsun
name: Kim, Il-Joong
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present far-ultraviolet (FUV) spectral images, measured at C IV 1550, He II 1640, Si IV+O IV] 1400, and O III] 1664, of the entire Cygnus Loop, observed with the Spectroscopy of Plasma Evolution from Astrophysical Radiation (SPEAR) instrument, also known as FIMS. The spatial distribution of FUV emission generally corresponds with a limb-brightened shell, and is similar to optical, radio and X-ray images. The features found in the present work include a ``carrot'', diffuse interior, and breakout features, which have not been seen in previous FUV studies. Shock velocities of 140-160 km/s is found from a line ratio of O IV] to O III], which is insensitive not only to resonance scattering but also to elemental abundance. The estimated velocity indicates that the fast shocks are widespread across the remnant. By comparing various line ratios with steady-state shock models, it is also shown that the resonance scattering is widespread.
description: 13 pages, 3 figures, 1 table, accepted for publication in ApJL
Competition and Dynamics in Trade Patterns: Hungarian and Slovenian Agri-Food Trade with the European Unions' Trading Partners
Creators: name: Bojnec, Stefan
name: Ferto, Imre
name: Bojnec, Stefan
name: Ferto, Imre
Publisher: name: Unknown
Year: 2006
Subjects: subject: International Relations/Trade
subject: Competition
subject: trade types
subject: dynamics
subject: mobility index
subject: F12
subject: Q17
subject: Q18

description: Trade balances and unit values in Hungarian and Slovenian bilateral agri-food trade with Austria, Germany and Italy, respectively, to distinguish types of the one-way and the two-way trade flows, categories of price competition and categories of quality competition in the twoway trade flows, their dynamics and stability over time are analyzed. The two-way matched trade flows prevail among trade types. In the matched two-way bilateral agri-food trade there is prevalence of categories of price competition over categories of non-price competition, but varies across trading partners. In Hungarian agri-food trade the first category of successful price competition and the third category of successful non-price or quality competition prevail, suggesting comparative advantages for Hungarian agri-food products vis-a-vis bilateral trading partners. In Slovenian agri-food trade the prevalence is on the second category of non-successful price competition and on the fourth category of non-successful quality competition suggesting comparative trade disadvantages vis-à-vis bilateral trading partners. Looking dynamically, we did not find comparative catch up as for Hungary both successful price and successful non-price competition increased only with Austria, but deteriorate with Germany and Italy. For Slovenia, successful price and successful non-price competition remains at similar level with Austria, but similar as for Hungary, they declined with Germany and Italy. The probability of remaining the one-way trade is greater than the probability to stay within the same competition category in the two-way matched trade. While there are differences across countries, products, and over individual years, the mobility indices indicate the decline in mobility in trade flows. If these patterns continue, then more stable trade patterns are expected.
Unambiguous spin-gauge formulation of canonical general relativity with conformorphism invariance
Creators: name: Wang, Charles H. -T.
Publisher: name: arXiv
Year: 2005
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We present a parameter-free gauge formulation of general relativity in terms of a new set of real spin connection variables. The theory is constructed by extending the phase space of the recently formulated conformal geometrodynamics for canonical gravity to accommodate a spin gauge description. This leads to a further enlarged set of first class gravitational constraints consisting of a reduced Hamiltonian constraint and the canonical generators for spin gauge and conformorphism transformations. Owing to the incorporated conformal symmetry, the new theory is shown to be free from an ambiguity of the Barbero-Immirzi type.
description: 4 pages; minor clarifications made; new refs added
High-pressure structural study of the scheelite tungstates CaWO4 and SrWO4
Creators: name: Errandonea, D.
name: Pellicer-Porres, J.
name: Manjon, F. J.
name: Segura, A.
name: Ferrer, Ch.
name: Kumar, R. S.
name: Tschauner, O.
name: Rodriguez-Hernandez, P.
name: Lopez-Solano, J.
name: Radescu, S.
name: Mujica, A.
name: Munoz, A.
name: Aquilanti, G.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Instrumentation and Detectors (physics.ins-det)
subject: FOS: Physical sciences

description: Angle-dispersive x-ray diffraction (ADXRD) and x-ray absorption near edge structure (XANES) measurements have been performed in the AWO4 tungstates CaWO4 and SrWO4 under high pressure up to approximately 20 GPa. Similar phase transitions and phase transition pressures have been observed for both tungstates using the two techniques in the studied pressure range. Both materials are found to undergo a pressure-induced scheelite-to-fergusonite phase transition under sufficiently hydrostatic conditions. Our results are compared to those found previously in the literature and supported by ab initio total energy calculations. From the total energy calculations we have also predicted a second phase transition from the fergusonite structure to a new structure identified as Cmca. Finally, a linear relationship between the charge density in the AO8 polyhedra of ABO4 scheelite-related structures and the bulk modulus is discussed and used to predict the bulk modulus of other materials, like zircon.
description: 52 pages, 9 figure, 4 tables
Magnetoresistance scaling, disorder, `hot spots' and the origin of $T$-linear resistivity in BaFe$_2$(As$_{1-x}$P$_x$)$_2$
Creators: name: Maksimovic, Nikola
name: Hayes, Ian M.
name: Nagarajan, Vikram
name: Koshelev, Alexei E.
name: Singleton, John
name: Lee, Yeonbae
name: Schenkel, Thomas
name: Analytis, James G.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: The scaling of $H$-linear magnetoresistance in field and temperature was measured in under-doped (x = 0.19) and optimally-doped (x=0.31)~BaFe$_2$(As$_{1-x}$P$_x$)$_2$. We analyze the data based on an orbital model in the presence of strongly anisotropic quasiparticle spectra and scattering time due to antiferromagnetism. The magnetoresistance is dominated by the properties of small regions of the Fermi surface called `hot spots' where antiferromagnetic excitations induce a large quasiparticle scattering rate. Approximate temperature-magnetic field scaling relations are derived and shown to be consistent with the experimental data. We argue that these results link the origin of linear-in-temperature resistivity to hot spots arising from an antiferromagnetic critical point, and magnetoresistance measurements provide a route to quantify this link.
description: 9 pages, 4 figures, Supplemental Material available on request
Coulomb corrections to the extrinsic spin-Hall effect of a two-dimensional electron gas
Creators: name: Hankiewicz, E. M.
name: Vignale, Giovanni
Publisher: name: arXiv
Year: 2005
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We develop the microscopic theory of the extrinsic spin Hall conductivity of a two-dimensional electron gas, including skew-scattering, side-jump, and Coulomb interaction effects. We find that while the spin-Hall conductivity connected with the side-jump is independent of the strength of electron-electron interactions, the skew-scattering term is reduced by the spin-Coulomb drag, so the total spin current and the total spin-Hall conductivity are reduced for typical experimental mobilities. Further, we predict that in paramagnetic systems the spin-Coulomb drag reduces the spin accumulations in two different ways: (i) directly through the reduction of the skew-scattering contribution (ii) indirectly through the reduction of the spin diffusion length. Explicit expressions for the various contributions to the spin Hall conductivity are obtained using an exactly solvable model of the skew-scattering.
description: The Coulomb corrections to the spin-Hall conductivity and spin accumulations to first order in strength of spin-orbit coupling and electron-electron interactions are included
Stock Price Prediction and Traditional Models: An Approach to Achieve Short-, Medium- and Long-Term Goals
Creators: name: Alamu, Opeyemi Sheu
name: Siam, Md Kamrul
Publisher: name: arXiv
Year: 2024
Subjects: subject: Statistical Finance (q-fin.ST)
subject: Machine Learning (cs.LG)
subject: Computational Finance (q-fin.CP)
subject: FOS: Economics and business
subject: FOS: Computer and information sciences

description: A comparative analysis of deep learning models and traditional statistical methods for stock price prediction uses data from the Nigerian stock exchange. Historical data, including daily prices and trading volumes, are employed to implement models such as Long Short Term Memory (LSTM) networks, Gated Recurrent Units (GRUs), Autoregressive Integrated Moving Average (ARIMA), and Autoregressive Moving Average (ARMA). These models are assessed over three-time horizons: short-term (1 year), medium-term (2.5 years), and long-term (5 years), with performance measured by Mean Squared Error (MSE) and Mean Absolute Error (MAE). The stability of the time series is tested using the Augmented Dickey-Fuller (ADF) test. Results reveal that deep learning models, particularly LSTM, outperform traditional methods by capturing complex, nonlinear patterns in the data, resulting in more accurate predictions. However, these models require greater computational resources and offer less interpretability than traditional approaches. The findings highlight the potential of deep learning for improving financial forecasting and investment strategies. Future research could incorporate external factors such as social media sentiment and economic indicators, refine model architectures, and explore real-time applications to enhance prediction accuracy and scalability.
description: 20 pages
Modelling activated sludge treatment of pulp and paper wastewater
Creators: name: Sreckovic, Goran
Publisher: name: University of British Columbia
Year: 2009

description: The research aim was to develop a mathematical model for predicting the behaviour of an activated sludge plant treating pulp and paper wastewater. A one-dimensional mechanistic model for the primary and secondary clarifiers was selected. The Activated Sludge Model No. 1, selected for the bioreactor, was modified to include components and processes related to activated sludge treatment of pulp and paper wastewaters. The mechanistic models were calibrated against data originating from full-scale facilities using genetic algorithms. The mechanistic models were connected to neural networks to form hybrid models. The response of the primary clarifier mechanistic model was fair for both overflow and underflow suspended solids. The hybrid model did not improve the mechanistic model response. The secondary clarifier mechanistic model response was very good for the underflow suspended solids and poor for the overflow suspended solids. A hybrid model improved the secondary clarifier mechanistic model in predicting overflow suspended solids concentrations. The neural network model introduced pH and BOD5 as variables related to clarification. The activated sludge mechanistic model predictions for effluent COD, mixed liquor suspended solids, phosphorus and oxygen uptake rate were very good. The model response was acceptable for nitrite plus nitrate, but inadequate for ammonia. The steady-state neural network model did not improve the activated sludge mechanistic model predictions. Temperature- and pH-dependent growth and decay rates were introduced in the activated sludge mechanistic model to gain an insight into the impact of variable model parameters on the overall model predictions. A conclusion was that a reason for using the pH- and temperature-dependent parameters existed only if the model responses for readily biodegradable COD and oxygen consumption were sought. The introduction of different coefficients representing the COD content of active biomass and a remaining portion of the mixed liquor suspended solids provided better model predictions for effluent COD and mixed liquor suspended solids The calibration results indicated the importance of having long term, dynamic data for both influent and effluent COD fractions to improve model accuracy. Thus, a need for extending full scale plant measurements to include influent and effluent COD fraction measurements was recognized.