cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Diffusive escape through a narrow opening: new insights into a classic problem
Creators: name: Grebenkov, Denis S
name: Oshanin, Gleb
Publisher: name: arXiv
Year: 2016
Subjects: subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: We study the mean first exit time $T_{\ve}$ of a particle diffusing in a circular or a spherical micro-domain with an impenetrable confining boundary containing a small escape window (EW) of an angular size $\ve$. Focusing on the effects of an energy/entropy barrier at the EW, and of the long-range interactions (LRI) with the boundary on the diffusive search for the EW, we develop a self-consistent approximation to derive for $T_{\ve}$ a general expression, akin to the celebrated Collins-Kimball relation in chemical kinetics and accounting for both rate-controlling factors in an explicit way. Our analysis reveals that the barrier-induced contribution to $T_{\ve}$ is the dominant one in the limit $\ve \to 0$, implying that the narrow escape problem is not "diffusion-limited" but rather "barrier-limited". We present the small-$\ve$ expansion for $T_{\ve}$, in which the coefficients in front of the leading terms are expressed via some integrals and derivatives of the LRI potential. On example of a triangular-well potential, we show that $T_{\ve}$ is non-monotonic with respect to the extent of the attractive LRI, being minimal for the ones having an intermediate extent, neither too concentrated on the boundary nor penetrating too deeply into the bulk. Our analytical predictions are in a good agreement with the numerical simulations.
description: 17 pages, 6 figures, Supplemental Materials
The Geometry of Small Causal Cones
Creators: name: Jubb, Ian
Publisher: name: arXiv
Year: 2016
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We derive a formula for the spacetime volume of a small causal cone. We use this formula within the context of causal set theory to construct causal set expressions for certain geometric quantities relating to a spacetime with a spacelike hypersurface. We also consider a scalar field on the causal set, and obtain causal set expressions relating to its normal derivatives with respect to the hypersurface.
Quantum integrable multi-well tunneling models
Creators: name: Ymai, L H
name: Tonel, A P
name: Foerster, A
name: Links, J
Publisher: name: arXiv
Year: 2016
Subjects: subject: Mathematical Physics (math-ph)
subject: Quantum Gases (cond-mat.quant-gas)
subject: Exactly Solvable and Integrable Systems (nlin.SI)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: In this work we present a general construction of integrable models for boson tunneling in multi-well systems. We show how the models may be derived through the Quantum Inverse Scattering Method and solved by algebraic Bethe ansatz means. From the transfer matrix we find only two conserved operators. However, we construct additional conserved operators through a different method. As a consequence the models admit multiple pseudovacua, each associated to a set of Bethe ansatz equations. We show that all sets of Bethe ansatz equations are needed to obtain a complete set of eigenstates.
description: 14 pages, 1 figure
Braiding without Braiding: Teleportation-Based Quantum Information Processing with Majorana Zero Modes
Creators: name: Vijay, Sagar
name: Fu, Liang
Publisher: name: arXiv
Year: 2016
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We present a new measurement-based scheme for performing braiding operations on Majorana zero modes and for detecting their non-Abelian statistics without moving or hybridizing them. In our scheme, the topological qubit encoded in any pair of well-separated Majorana zero modes in a mesoscopic superconductor island is read out from the transmission phase shift in electron teleportation through the island in the Coulomb blockade regime. We propose experimental setups to measure the teleportation phase shift via conductance in an electron interferometer or persistent current in a closed loop.
description: 11 pages, 6 figures
Subdiffusion in classical and quantum nonlinear Schrödinger equations with disorder
Creators: name: Iomin, A.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Chaotic Dynamics (nlin.CD)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: The review is concerned with the nonlinear Schrödinger equation (NLSE) in the presence of disorder. Disorder leads to localization in the form of the localized Anderson modes (AM), while nonlinearity is responsible for the interaction between the AMs and transport. The dynamics of an initially localized wave packets are concerned in both classical and quantum cases. In both cases, there is a subdiffusive spreading, which is explained in the framework of a continuous time random walk (CTRW), and it is shown that subdiffusion is due to the transitions between those AMs, which are strongly overlapped. This overlapping being a common feature of both classical and quantum dynamics, leads to the clustering with an effective trapping of the wave packet inside each cluster. Therefore, the dynamics of the wave packet corresponds to the CTRW, where the basic mechanism of subdiffusion is an entrapping of the wave packet with delay, or waiting, times distributed by the power law $w(t)\sim 1/t^{1+α}$, where $α$ is the transport exponent. It is obtained that $α=1/3$ for the classical NLSE and $α=1/2$ for the quantum NLSE.
description: Computers and Mathematics with Applications (in Press). arXiv admin note: text overlap with arXiv:0909.2112
title: Διερεύνηση δομικών βλαβών και μεθόδων επεμβάσεων σε ενετικούς μονόχωρους καμαροσκέπαστους ναούς της Δυτικής Κρήτης

title: Investigation of structural damage and intervention methods in Venetian single-chamber arched temples of Western Crete
Creators: name: Δαρμαρακης Παναγιωτης
Publisher: name: Technical University of Crete
Year: 2023

description: Αποτελεί πραγματικότητα πως ένας από τους κυρίαρχους αρχιτεκτονικούς ρυθμούς δόμησης ναών στην δυτική Κρήτη, κατά την περίοδο της ενετοκρατίας,  ήταν εκείνος του « μονόχωρου καμαροσκέπαστου ». Πλήθος ναών  της περιόδου αυτής έχει αποκατασταθεί πρόσφατα ενώ μέρος αυτών παρουσιάζει σοβαρές βλάβες. Καταδεικνύεται έτσι η ανάγκη της διερεύνησης των κύριων αιτιών των δομικών βλαβών που λαμβάνουν χώρα σε αυτούς, με σκοπό την εφαρμογή των πλέον βέλτιστων επεμβάσεων για την αποκατάσταση τους.
Στόχος της παρούσας εργασίας είναι να γίνει η καταγραφή και η διερεύνηση των αιτιών των κυριότερων δομικών βλαβών που παρουσιάζονται στον συγκεκριμένο τύπο ναών στην περιοχή δυτικής Κρήτης. Στο πρώτο στάδιο της εργασίας περιλαμβάνεται  η διερεύνηση των δομικών βλαβών, σε ναούς με αντιστοιχία στις αναλογίες διαστάσεων, διαμέσου φωτογραφικής τεκμηρίωσης. Σε δεύτερο στάδιο, θα γίνεται επιλογή ναών με τις χαρακτηριστικότερες δομικές βλάβες με σκοπό την δημιουργία ψηφιακών μοντέλων για την διεξαγωγή στατικών και δυναμικών αναλύσεων με την μέθοδο των πεπερασμένων στοιχείων. Στο τρίτο στάδιο με βάση τα ανωτέρω πραγματοποιείται τυποποίηση των αιτιών και των κυριότερων δομικών βλαβών που εμφανίζονται σε αυτού του τύπου τους ναούς. Τέλος, από τα στοιχεία που αναλύθηκαν δίνεται πρόταση επεμβάσεων αποκατάστασης των μελετώμενων ναών λαμβάνοντας υπόψιν τις ιδιαιτερότητες του κάθε μνημείο σε συνδυασμό με τις σύγχρονες αρχές αποκατάστασης που έχουν θεσπιστεί.
A two-component generalization of the reduced Ostrovsky equation and its integrable semi-discrete analogue
Creators: name: Feng, Bao-Feng
name: Maruno, Ken-ichi
name: Ohta, Yasuhiro
Publisher: name: arXiv
Year: 2016
Subjects: subject: Exactly Solvable and Integrable Systems (nlin.SI)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: In the present paper, we propose a two-component generalization of the reduced Ostrovsky equation, whose differential form can be viewed as the short-wave limit of a two-component Degasperis-Procesi (DP) equation. They are integrable due to the existence of Lax pairs. Moreover, we have shown that two-component reduced Ostrovsky equation can be reduced from an extended BKP hierarchy with negative flow through a pseudo 3-reduction and a hodograph (reciprocal) transform. As a by-product, its bilinear form and $N$-soliton solution in terms of pfaffians are presented. One- and two-soliton solutions are provided and analyzed. In the second part of the paper, we start with a modified BKP hierarchy, which is a Bäcklund transformation of the above extended BKP hierarchy, an integrable semi-discrete analogue of two-component reduced Ostrovsky equation is constructed by defining an appropriate discrete hodograph transform and dependent variable transformations. Especially, the backward difference form of above semi-discrete two-component reduced Ostrovsky equation gives rise to the integrable semi-discretization of the short wave limit of a two-component DP equation. Their $N$-soliton solutions in terms of pffafians are also provided.
description: 15 pages, 4 figures with corrections to original submission
Yet another p-adic hyperbolic disc
Creators: name: Guilloux, Antonin
Publisher: name: arXiv
Year: 2016
Subjects: subject: Geometric Topology (math.GT)
subject: FOS: Mathematics

description: We describe in this paper a geometric construction in the projective p-adic plane that gives, together with a suitable notion of p-adic convexity, some open subsets of P 2 .Q p / naturally endowed with a "Hilbert" distance and a transitive action of PGL.2; Q p / by isometries. ese open sets are natural analogues of the hyperbolic disc, more precisely of Klein's projective model. But, unlike the real case, there is not only one such hyperbolic disc. Indeed, we nd three of them if p is odd (and seven if p D 2). Let us stress out that neither the usual notion of convexity nor that of connectedness as known for the real case are meaningful in the p-adic case. us, there will be a rephrasing game for the denitions of real convexity until we reach a formulation suitable for other local elds. It will lead us to a denition of p-adic convexity by duality. Although we will not recover the beautiful behaviour of real convexity, we will still be able to dene the most important tool for our goals, namely the Hilbert distance. We construct our analogues of the hyperbolic disc (once again, via the projective model of the hyperbolic plane) in a quite geometric, even naive, way. Our construction gives 2-dimensional objects over Q p. It is very dierent, in spirit and in facts, of Drinfeld p-adic hyperbolic plane []. e possible relations between the two objects remain still unexplored. Another object often viewed as an analogue of the hyperbolic disc is the tree of PGL.2; Q p / []. We explore the relations between our discs and this tree, constructing a natural quasi-isometric projection from the discs to the tree. Eventually we explore the transformation groups of our discs. And, whereas the transformation group of the tree is huge, we prove that only PGL.2; Q p / acts on the discs preserving the convex structure.
A Critical Examination of Nigeria's Electricity Generation and Supply between 2001 and 2020
Creators: name: Otobo, Justicia Chimuanya
Publisher: name: London South Bank University
Year: 2023

description: This study focuses on Nigeria's journey towards achieving the United Nations' 7th Sustainable Energy Goal by 2030, which aims to provide cheap, sustainable, and reliable energy access worldwide. It reviews Nigeria's electricity policies from 2001 to 2020 and employs a deterministic modelling tool to identify the least-cost electrification options for the entire country. Nigeria, being in its early economic stages, is advised to promote renewable energy to diversify its energy mix and build renewable power plants. This shift towards renewables is seen as advantageous. The modelling tool introduced allows policymakers, even those without technical expertise, to assess the potential impacts of their decisions before implementation. The study's projections indicate that a combination of renewable and non-renewable energy sources is the optimal path for Nigeria's future energy network. However, challenges such as oil price fluctuations, supply chain issues, and a high cost of living may slow the adoption of renewable energy. Two scenarios are examined: the Forecast scenario based on the current national grid performance and the Policy scenario aligning with the Nigerian Government's 2030 electrification plan. Both scenarios suggest that increasing transmission lines and power generation while integrating renewables can significantly reduce operational costs. Currently, only about 60% of Nigeria's population has access to electricity, and it is often unreliable. To support economic growth and population needs, the study emphasises the necessity of incorporating more renewable energy sources in Nigeria's energy expansion plans. Climate change and global warming underscore the importance of a resilient and stable energy sector. Furthermore, the study identifies policies that have contributed to electricity generation and supply, especially in rural and off-grid areas. These policies encourage investment, support diverse energy sources, and involve various stakeholders in the electricity value chain. By implementing the right regulations to attract renewable energy investors, Nigeria can address its power sector issues and expand electricity access to unconnected regions. In conclusion, Nigeria's path to sustainable and reliable energy involves a balanced mix of renewable and non-renewable sources, improved policies, and investments in untapped natural resources like solar, wind, biomass, and tidal energy. This approach can create a cleaner, more sustainable energy future for the country.
The Galaxy Kinematics from OB Stars with Proper Motions from the Gaia DR1 Catalog
Creators: name: Bobylev, V. V.
name: Bajkova, A. T.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We consider two previously studied samples of OB stars with different distance scales. The first one consists of 98 massive spectroscopic binary stars with photometric distances, and the second one consists on 140 OB stars with the distances determined along the lines of interstellar calcium. The OB stars are located at distances up to 7 kpc from the Sun. They are identified with the Gaia DR1 catalog. It is shown that the use of the proper motions, taken from the Gaia DR1 catalog, allows to reduce random errors of determination of the Galactic rotation parameters in comparison with the previously known ones. From the analysis of 208 OB stars from the Gaia DR1 catalog with proper motions and parallaxes with relative errors less than 200% we found the Galactic kinematic parameters. In addition the Galactic rotation parameters were obtained from only line-of-sight velocities of the same stars. From the comparison of the two values of Ω^{'}_0 a distance scale of the Gaia DR1 catalog was determined as a value close to unit, namely 0.96. From 238 OB-stars of the united sample with photometric distances for stars of the first sample and distances in the calcium scale for stars of the second sample, line-of-sight velocities and proper motions from the Gaia DR1 catalog, were found the following kinematic parameters: (U,V,W)_\odot=(8.19,9.28,8.79)+/-(0.74,0.92,0.74) km/s, Ω_0=31.53+/-0.54 km/s/kpc, Ω^{'}_0=-4.44+/-0.12 km/s/kpc^2, Ω^{"}_0=0.706+/-0.100 km/s/kpc^3, here Oort constants: A=-17.77+/-0.46 km/s/kpc, B=13.76+/-0.71 km/s/kpc and V_0=252+/-8 km/s.
description: 12 pages, 3 figures, accepted for publication in Astronomy Letters (2017, Issue 3). arXiv admin note: text overlap with arXiv:1507.08049
Picosecond spin Seebeck effect
Creators: name: Kimling, Johannes
name: Choi, Gyung-Min
name: Brangham, Jack T.
name: Matalla-Wagner, Tristan
name: Huebner, Torsten
name: Kuschel, Timo
name: Yang, Fengyuan
name: Cahill, David G.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We report time-resolved magneto-optic Kerr effect measurements of the longitudinal spin Seebeck effect driven by an interfacial temperature difference between itinerant electrons and magnons. The measured time-evolution of spin accumulation induced by laser-excitation indicates transfer of angular momentum across Au/Y$_3$Fe$_5$O$_{12}$ and Cu/Y$_3$Fe$_5$O$_{12}$ interfaces on a picosecond time-scale. The product of spin-mixing conductance and interfacial spin Seebeck coefficient determined is of the order of $10^8$ A m$^{-2}$ K$^{-1}$.
description: 16 pages, 4 figures, 1 table
Magnetic properties of the $α$-$T_3$ model: magneto-optical conductivity and the Hofstadter butterfly
Creators: name: Illes, E.
name: Nicol, E. J.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: The $α$-$T_3$ model extrapolates between the pseudospin $S=1/2$ honeycomb lattice of graphene and the pseudospin $S=1$ dice lattice via parameter $α$. We present calculations of the magnetic properties of this hybrid pseudospin model, namely the absorptive magneto-optical conductivity and the Hofstadter butterfly spectra. In the magneto-optics curves, signatures of the hybrid system corollary a doublet structure present in the peaks, resulting from differing Landau level energies in the $K$ and $K^{\prime}$ valleys. In the Hofstadter spectra, we detail the evolution of the Hofstadter butterfly as it changes its periodicity by a factor of three as we vary between the two limiting cases of the $α$-$T_3$ model.
description: 12 pages, 11 figures, submitted to Phys. Rev. B on May 30, 2016
On the dynamics of the mean-field polaron in the weak-coupling limit
Creators: name: Griesemer, Marcel
name: Schmid, Jochen
name: Schneider, Guido
Publisher: name: arXiv
Year: 2016
Subjects: subject: Mathematical Physics (math-ph)
subject: Analysis of PDEs (math.AP)
subject: FOS: Physical sciences
subject: FOS: Mathematics
subject: 35Q55 (Primary) 35B25, 81V99 (Secondary)

description: We consider the dynamics of the mean-field polaron in the weak-coupling limit of vanishing electron-phonon interaction, $\varepsilon \to 0$. This is a singular limit formally leading to a Schrödinger--Poisson system that is equivalent to the nonlinear Choquard equation. By establishing estimates between the approximation obtained via the Choquard equation and true solutions of the original system we show that the Choquard equation makes correct predictions about the dynamics of the polaron mean-field model for small values of $\varepsilon > 0$.
description: 14 pages
Quark and gluon form factors to four loop order in QCD: the $N_f^3$ contributions
Creators: name: von Manteuffel, Andreas
name: Schabinger, Robert M.
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We calculate the four-loop massless QCD corrections with three closed quark lines to quark and gluon form factors. We apply a novel integration by parts algorithm based on modular arithmetic and compute all relevant master integrals for arbitrary values of the space-time dimension. This is the first calculation of a gluon form factor at this perturbative order in QCD.
description: 4 pages
A fractionalised "$\mathbb{Z}_2$" classical Heisenberg spin liquid
Creators: name: Rehn, J.
name: Sen, Arnab
name: Moessner, R.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: Quantum spin systems are by now known to exhibit a large number of different classes of spin liquid phases. By contrast, for \textit{classical} Heisenberg models, only one kind of fractionalised spin liquid phase, the so-called Coulomb or $U(1)$ spin liquid, has until recently been identified: this exhibits algebraic spin correlations and impurity moments, `orphan spins', whose size is a fraction of that of the underlying microscopic degrees of freedom. Here, we present two Heisenberg models exhibiting fractionalisation in combination with exponentially decaying correlations. These can be thought of as a classical continuous spin version of a $\mathbb{Z}_2$ spin liquid. Our work suggests a systematic search and classification of classical spin liquids as a worthwhile endeavour.
description: 5 pages, 7 figures
A SINFONI view of the nuclear activity and circum-nuclear star formation in NGC 4303
Creators: name: Riffel, Rogemar A.
name: Colina, L.
name: Storchi-Bergmann, T.
name: Lopez, J. Piqueras
name: Arribas, S.
name: Riffel, R.
name: Pastoriza, M.
name: Sales, Dinalva A.
name: Dametto, N. Z.
name: Labiano, A.
name: Davies, R. I.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We present new maps of emission-line flux distributions and kinematics in both ionized (traced by HI and [FeII] lines) and molecular (H2) gas of the inner 0.7x0.7kpc2 of the galaxy NGC4303, with a spatial resolution 40-80pc and velocity resolution 90-150 km/s obtained from near-IR integral field specroscopy using the VLT instrument SINFONI. The most promiment feature is a 200-250pc ring of circum-nuclear star-forming regions. The emission from ionized and molecular gas shows distinct flux distributions: while the strongest HI and [FeII] emission comes from regions in the west side of the ring (ages~4Myr), the H2 emission is strongest at the nucleus and in the east side of the ring (ages>10Myr). We find that regions of enhanced hot H2 emission are anti-correlated with those of enhanced [FeII] and HI emission, which can be attributed to post starburst regions that do not have ionizing photons anymore but still are hot enough (~2000K) to excite the H2 molecule. The line ratios are consistent with the presence of an AGN at the nucleus. The youngest regions have stellar masses in the range 0.3-1.5E5 MSun and ionized and hot molecular gas masses of ~0.25-1.2E4 Msun and 2.5-5 Msun, respectively. The stellar and gas velocity fields show a rotation pattern, with the gas presenting larger velocity amplitudes than the stars, with a deviation observed for the H2 along the nuclear bar, where increased velocity dispersion is also observed, possibly associated with non circular motions along the bar. The stars in the ring show smaller velocity dispersion than the surroundings, that can be attributed to a cooler dynamics due to their recent formation from cool gas.
description: 15 pages, accepted for publication in MNRAS
The large sum graph related to comultiplication modules
Creators: name: Ansari-Toroghy, H.
name: Mahboobi-Abkenar, F.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Commutative Algebra (math.AC)
subject: FOS: Mathematics
subject: 05C75, 13A99, 05C99

description: Let R be a commutative ring and M be an R-module. We define the large sum graph, denoted by \acute{G}(M), as a graph with the vertex set of non-large submodules of M and two distinct vertices are adjacent if and only if N + K is a non-large submodule of M. In this article, we investigate the connection between the graph-theoretic properties of \acute{G}(M) and some algebraic properties of M when M is a comultiplication R-module.
The Effect of Leadership Style on the Performance of Civil Service Organizations in Addis Ababa City Administration
Creators: name: Gebremedhin, Goitom
Publisher: name: African Journal of Leadership and Development
Year: 2021

description: The main purpose of this study was to analyse the effect of leadership styles on the performance of civil service organization of Addis Ababa city administration. The study has employed concurrent mixed research, and both descriptive and explanatory research designs. The study has included 400 sample employees. Purposive and simple random sampling (lottery method) were used to select and access the sample key informants and for questionnaire distribution respectively. Both primary and secondary data were used. The data was collected using questionnaires, key informant interviews, and FGD. The quantitative data was analyzed using descriptive and inferential statistical (regression) analysis. On the other hand, the qualitative data was analyzed using thematic analysis. The findings of the study show that the current level of performance of the civil service organizations is found to be low. Autocratic leadership is a dominant leadership style practiced in the study area, followed by democratic style. Laissez-faire leadership is relatively less practiced but has a positive and insignificant effect on organizational performance. Though, autocratic leadership style is dominant, it has significant negative effect on the performance of organizations. As a result, it has been suggested to the organizations and/or leaders to dominantly exercise democratic leadership styles and benevolent autocratic leadership styles, for in order to boost organizational performance.
description: African Journal of Leadership and Development, Vol. 6 No. 2 (2021): Organizational Leadership and Perfromance
Character analogue of the Boole summation formula with applications
Creators: name: Can, Mümün
name: Dagli, M. Cihat
Publisher: name: arXiv
Year: 2016
Subjects: subject: Number Theory (math.NT)
subject: FOS: Mathematics
subject: 65B15, 11M06, 11F20, 11B68

description: In this paper, we present the character analogue of the Boole summation formula. Using this formula, an integral representation is derived for the alternating Dirichlet $L-$function and its derivative is evaluated at $s=0$. Some applications of the character analogue of the Boole summation formula and the integral representation are given about the alternating Dirichlet $L-$function. Moreover, the reciprocity formulas for two new arithmetic sums, arising from utilizing the summation formulas, and for Hardy--Berndt sum $S_{p}\left( b,c:χ\right) $ are proved.
Supplementary document for Diffraction-gated real-time ultrahigh-speed mapping photography - 6526433.pdf
Creators: name: Liang, Jinyang
name: Liu, Xianglei
name: Kilcullen, Patrick
name: Wang, Youmin
name: Helfield, Brandon
Publisher: name: Optica Publishing Group
Year: 2023
Subjects: Engineering Instrumentation

description: Revised Supplement 1
Was Venus the First Habitable World of our Solar System?
Creators: name: Way, Michael J.
name: Del Genio, Anthony D.
name: Kiang, Nancy Y.
name: Sohl, Linda E.
name: Grinspoon, David H.
name: Aleinov, Igor
name: Kelley, Maxwell
name: Clune, Thomas
Publisher: name: arXiv
Year: 2016
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: Present-day Venus is an inhospitable place with surface temperatures approaching 750K and an atmosphere over 90 times as thick as present day Earth's. Billions of years ago the picture may have been very different. We have created a suite of 3D climate simulations using topographic data from the Magellan mission, solar spectral irradiance estimates for 2.9 and 0.715 billion years ago, present day Venus orbital parameters, an ocean volume consistent with current theory and measurements, and an atmospheric composition estimated for early Venus. Using these parameters we find that such a world could have had moderate temperatures if Venus had a rotation period slower than about 16 Earth days, despite an incident solar flux 46-70% higher than modern Earth receives. At its current rotation period of 243 days, Venus's climate could have remained habitable until at least 715 million years ago if it hosted a shallow primordial ocean. These results demonstrate the vital role that rotation and topography play in understanding the climatic history of exoplanetary Venus-like worlds being discovered in the present epoch.
description: 13 pages, 4 Figures, submitted to Geophysical Research Letters
Multiuser Detection in Multibeam Satellite Systems: Theoretical Analysis and Practical Schemes
Creators: name: Colavolpe, Giulio
name: Modenini, Andrea
name: Piemontese, Amina
name: Ugolini, Alessandro
Publisher: name: arXiv
Year: 2016
Subjects: subject: Information Theory (cs.IT)
subject: FOS: Computer and information sciences

description: We consider the rates achievable by a user in a multibeam satellite system for unicast applications, and propose alternatives to the conventional single-user symbol-by-symbol detection applied at user terminals. Single-user detection is known to suffer from strong degradation when the terminal is located near the edge of the coverage area of a beam, and when aggressive frequency reuse is adopted. For this reason, we consider multiuser detection, and take into account the strongest interfering signal. We also analyze two additional transmission strategies requiring modifications at medium access control layer. We describe an information-theoretic framework to compare the different strategies by computing the information rate of the user in the reference beam. Furthermore, we analyze the performance of coded schemes that could approach the information-theoretic limits. We show that classical codes from the DVB-S2(X) standard are not suitable when multiuser detection is adopted, and we propose two ways to improve the performance, based on the redesign of the code and of the bit mapping.
description: 30 pages, 21 figures, submitted to IEEE Trans. Commun
Finitely generated and not finitely generated rings
Creators: name: Nathanson, Melvyn B.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Commutative Algebra (math.AC)
subject: FOS: Mathematics
subject: 13E15, 13B02, 13E05, 13F20

description: Let $R_1$ be a commutative ring, let $R_2$ be a finitely generated extension ring of $R_1$, and let $S$ be a ring that is intermediate between $R_1$ and $R_2$. For $R_1 = R[x]$ and $R_2 = R[x,y]$, this paper gives simple combinatorial constructions of intermediate rings $S$ that are not finitely generated over $R[x]$.
description: 3 pages
Unconventional temperature dependence of the cuprate excitation spectrum
Creators: name: Sacks, William
name: Mauger, Alain
name: Noat, Yves
Publisher: name: arXiv
Year: 2016
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: Key properties of the cuprates, such as the pseudogap observed above the critical temperature $T_c$, remain highly debated. Given their importance, we recently proposed a novel mechanism based on the Bose-like condensation of mutually interacting Cooper pairs [W. Sacks, A. Mauger, Y. Noat, Superconduct. Sci. Technol. 28 105014, (2015)]. In this work, we calculate the temperature dependent DOS using this model for different doping levels from underdoped to overdoped. In all situations, due to the presence of excited pairs, a pseudogap is found above $T_c$ while the normal DOS is recovered at $T^*$, the pair formation temperature. A similar behavior is found as a function of magnetic field, crossing a vortex, where a pseudogap exists in the vortex core. We show that the precise DOS shape depends on combined pair (boson) and quasiparticle (fermion) excitations, allowing for a deeper understanding of the SC to the PG transition.
description: Accepted in the European Physical Journal B (EPJB)
Source clustering in the Hi-GAL survey determined using a minimum spanning tree method
Creators: name: Beuret, Maxime
name: Billot, Nicolas
name: Cambrésy, Laurent
name: Eden, David J.
name: Elia, Davide
name: Molinari, Sergio
name: Pezzuto, Stefano
name: Schisano, Eugenio
Publisher: name: arXiv
Year: 2016
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: The aims are to investigate the clustering of the far-infrared sources from the Herschel infrared Galactic Plane Survey (Hi-GAL) in the Galactic longitude range of -71 to 67 deg. These clumps, and their spatial distribution, are an imprint of the original conditions within a molecular cloud. This will produce a catalogue of over-densities. The minimum spanning tree (MST) method was used to identify the over-densities in two dimensions. The catalogue was further refined by folding in heliocentric distances, resulting in more reliable over-densities, which are cluster candidates. We found 1,633 over-densities with more than ten members. Of these, 496 are defined as cluster candidates because of the reliability of the distances, with a further 1,137 potential cluster candidates. The spatial distributions of the cluster candidates are different in the first and fourth quadrants, with all clusters following the spiral structure of the Milky Way. The cluster candidates are fractal. The clump mass functions of the clustered and isolated are statistically indistinguishable from each other and are consistent with Kroupa's initial mass function.
description: 24 pages, 27 figures
Kepler Eclipsing Binaries with $δ$ Scuti/$γ$ Doradus Pulsating Components 1: KIC 9851944
Creators: name: Guo, Zhao
name: Gies, Douglas R.
name: Matson, Rachel A.
name: Hernández, Antonio García
Publisher: name: arXiv
Year: 2016
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: KIC 9851944 is a short period ($P=2.16$ days) eclipsing binary in the {\it Kepler} field of view. By combining the analysis of {\it Kepler} photometry and phase resolved spectra from Kitt Peak National Observatory and Lowell Observatory, we determine the atmospheric and physical parameters of both stars. The two components have very different radii ($2.27R_{\odot}$, $3.19R_{\odot}$) but close masses ($1.76 M_{\odot}$, $1.79M_{\odot}$) and effective temperatures ($7026$K, $6902$K), indicating different evolutionary stages. The hotter primary is still on the main sequence (MS), while the cooler and larger secondary star has evolved to post-MS, burning hydrogen in a shell. A comparison with coeval evolutionary models shows that it requires solar metallicity and a higher mass ratio to fit the radii and temperatures of both stars simultaneously. Both components show $δ$ Scuti type pulsations which we interpret as p-modes and p and g mixed modes. After a close examination of the evolution of $δ$ Scuti pulsational frequencies, we make a comparison of the observed frequencies with those calculated from MESA/GYRE.
description: Accepted for publication in ApJ on May 05, 2016
Planet formation with envelope enrichment: new insights on planetary diversity
Creators: name: Venturini, Julia
name: Alibert, Yann
name: Benz, Willy
Publisher: name: arXiv
Year: 2016
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: We compute, for the first time, self-consistent models of planet growth including the effect of envelope enrichment. The change of envelope metallicity is assumed to be the result of planetesimal disruption or icy pebble sublimation. We solve internal structure equations taking into account global energy conservation for the envelope to compute in-situ planetary growth. We consider different opacities and equations of state suited for a wide range of metallicities. We find that envelope enrichment speeds up the formation of gas giants. It also explains naturally the formation of low and intermediate mass objects with large fractions of H-He (~ 20 - 30 % in mass). High opacity models explain well the metallicity of the giant planets of the solar system, whereas low opacity models are suited for forming small mass objects with thick H-He envelopes and gas giants with sub-solar envelope metallicities. We find good agreement between our models and the estimated water abundance for WASP-43b. For HD 189733b, HD 209458b and WASP-12b we predict fractions of water larger than what is estimated from observations, by at least a factor ~ 2. Envelope enrichment by icy planetesimals is the natural scenario to explain the formation of a large variety of objects, ranging from mini-Neptunes, to gas giants. We predict that the total and envelope metallicity decrease with planetary mass.
description: Accepted for publication in A&A
Women’s Perceived Participation in Leadership Position and the Perception of Academicians in Ethiopian Higher Learning Institutions
Creators: name: Ahmed, Amina
Publisher: name: African Journal of Leadership and Development
Year: 2021

description: Given the fact that the involvement of women in leadership position is minimal, The objectives of the study is to assess the participation of women in leadership position in selected higher learning institutions as well to compare the level of agreement to the barriers identified gender wise . To do so descriptive and explanatory research design and mixed research approach was applied. The questionnaires were randomly distributed to a sample 383 men and women academicians of four public universities found in Addis Ababa. In depth interview was made with gender focal persons and women office holder academicians while secondary data was gathered from the human resource management of the universities. The finding of the study shows that the participation of women in leadership position is minimal though improved from time to time.to this end personal, Institutional and traditional barriers are believed to contribute to the perceived participation of women in leadership position. The result of the Mann-Whitney U test shows that the perception of men academicians toward the factors affecting women’s participation in leadership position is significantly different from the perceptions of the women counterparts.
description: African Journal of Leadership and Development, Vol. 6 No. 2 (2021): Organizational Leadership and Perfromance
1 A Case Study of Livestock Prices in Nicaragua
Creators: name: Augustin, Jameson
name: Lopez, Jose A.
name: Leiva, Ervin
Publisher: name: Unknown
Year: 2021
Subjects: subject: Financial Economics
subject: Livestock Production/Industries
subject: Production Economics
subject: hedonic analysis
subject: feeder cattle
subject: futures market
subject: livestock auction data
subject: Nicaragua

description: Growing at an annual rate of 3.7%, the Latin American1 livestock sector surpasses the average global livestock growth rate of 2.1% (FAO, 2020a) and has become the leading region for beef and poultry exports worldwide (FAO, 2020a). We conduct a case study of livestock prices in Nicaragua, the leading meat producing country in Central America. Nicaragua’s livestock production is non- intensive and is expected to exhibit a growth rate of 24% between 2017 and 2018 (NCB, 2017). Using data on futures on feeder cattle prices from the Chicago Mercantile Exchange Group (CME) supplemented with data on 2,520 sales transactions from 99 auctions from 2017 to 2018 from the Nicaraguan Cattle Auction (NCA), this study conducts a hedonic price analysis for cattle auctioned in Nicaragua. In particular, the study empirically identifies factors affecting price differentials for cattle and examines its correlation with the futures market. Our results showed that weight, lot size (head), and class are all statistically significant factors impacting livestock auction prices while their correlation with the futures market is significant for six out of the eight futures variables corresponding to the contract months at the CME. The results of the study are of importance to buyers and sellers of cattle in their decision-making process and help them understand information from the futures market to predict price differences and reduce price risk and uncertainty.
Disentangling the Relationship Between Remittances and Peace
Creators: name: Syed, Ali Hamza
Publisher: name: University of Chicago
Year: 2022
Subjects: subject: remittances
subject: peace
subject: peacebuilding
subject: conflict

description: This study explores the relationship between remittances and peacebuilding. My hypothesis is that there is a statistically significant relationship between remittances and peace levels. I employ four multivariate regression models which control for social, economic, and political factors for countries over a given period. The results indicate that remittances have a statistically significant relationship with peacebuilding. I find that higher remittances as a percentage of GDP are linked to lower peace levels. Additionally, lower average transaction costs for migrants remitting back to their nations of origin are linked to lower levels of peace. The study also finds that the highest remittance receiving nations have a strong correlation with the lowest levels of peace. I identify the possible mechanisms for this relationship as being a combination of migrants having greater propensity to sustain the livelihoods of their families in areas of conflict and the lack of regulation leading to lower transaction fees in nations of conflict.
A new algorithm for optimizing the wavelength coverage for spectroscopic studies: Spectral Wavelength Optimization Code (SWOC)
Creators: name: Ruchti, G. R.
name: Feltzing, S.
name: Lind, K.
name: Caffau, E.
name: Korn, A. J.
name: Schnurr, O.
name: Hansen, C. J.
name: Koch, A.
name: Sbordone, L.
name: de Jong, R. S.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: The past decade and a half has seen the design and execution of several ground-based spectroscopic surveys, both Galactic and Extra-galactic. Additionally, new surveys are being designed that extend the boundaries of current surveys. In this context, many important considerations must be done when designing a spectrograph for the future. Among these is the determination of the optimum wavelength coverage. In this work, we present a new code for determining the wavelength ranges that provide the optimal amount of information to achieve the required science goals for a given survey. In its first mode, it utilizes a user-defined list of spectral features to compute a figure-of-merit for different spectral configurations. The second mode utilizes a set of flux-calibrated spectra, determining the spectral regions that show the largest differences among the spectra. Our algorithm is easily adaptable for any set of science requirements and any spectrograph design. We apply the algorithm to several examples, including 4MOST, showing the method yields important design constraints to the wavelength regions.
description: 27 pages, 4 figures, accepted to MNRAS
Service User Perception of Service Quality in Addis Ababa City Administration, Ethiopia
Creators: name: Timerga, Genanew
Publisher: name: African Journal of Leadership and Development
Year: 2021

description: Public sector organizations exist to provide services to citizens and citizens are service users, be it in public, private or other institutions. The purpose of this research is to evaluate the service quality gap in users’ perception in select public sector organizations in Addis Ababa City. A cross-sectional survey method was applied and the sampling was carried out across three select government organizations. A questionnaire and interview method was used to gather the data. As a mixed method study, the analysis consisted of both quantitative and qualitative approaches. The research targeted 415 subjects for their service user perceptions, but 402 questionnaires were completed successfully, giving a 96.87% response rate. 63.9% were male and 36.1% were female respondents. Near to half percent of the respondents were married and most of the respondent was 9—12 completed. A statistically significant mean difference was observed between the overall level of assurance expectation (t = 3.631, p < 0.01) but insignificant mean difference was observed in service user perception (t = 1.797, p > 0.05). From the regression result responsiveness, assurance and empathy were statistically significant predictors of service user perception with the (p < 0.05), whereas tangible and reliability were found to be statistically insignificant in this study area.
description: African Journal of Leadership and Development, Vol. 6 No. 2 (2021): Organizational Leadership and Perfromance
Wind Turbine Design: Multi-Objective Optimization
Creators: name: Chehouri, Adam
name: Younes, Rafic
name: Ilinca, Adrian
name: Perron, Jean
Publisher: name: arXiv
Year: 2016
Subjects: subject: Optimization and Control (math.OC)
subject: FOS: Mathematics

description: Within the last 20 years, wind turbines have reached matured and the growing worldwide wind energy market will allow further improvements. In the recent decades, the numbers of research papers that have applied optimization techniques in the attempt to obtain an optimal design have increased. The main target of manufacturers has been to minimize the cost of energy of wind turbines in order to compete with fossil-fuel sources. Therefore, it has been argued that it is more stimulating to evaluate the wind turbine design as an optimization problem consisting of more than one objective. Using multi-objective optimization algo- rithms, the designers are able to identify a trade-off curve called Pareto front that reveals the weaknesses, anomalies and rewards of certain targets. In this chapter, we present the fundamental principles of multi-objective optimization in wind turbine design and solve a classic multi-objective wind turbine optimization problem using a genetic algorithm.
The dependence of convective core overshooting on stellar mass
Creators: name: Claret, Antonio
name: Torres, Guillermo
Publisher: name: arXiv
Year: 2016
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Convective core overshooting extends the main-sequence lifetime of a star. Evolutionary tracks computed with overshooting are quite different from those that use the classical Schwarzschild criterion, which leads to rather different predictions for the stellar properties. Attempts over the last two decades to calibrate the degree of overshooting with stellar mass using detached double-lined eclipsing binaries have been largely inconclusive, mainly due to a lack of suitable observational data. Here we revisit the question of a possible mass dependence of overshooting with a more complete sample of binaries, and examine any additional relation there might be with evolutionary state or metal abundance Z. We use a carefully selected sample of 33 double-lined eclipsing binaries strategically positioned in the H-R diagram, with accurate absolute dimensions and component masses ranging from 1.2 to 4.4 solar masses. We compare their measured properties with stellar evolution calculations to infer semi-empirical values of the overshooting parameter alpha(ov) for each star. Our models use the common prescription for the overshoot distance d(ov) = alpha(ov) Hp, where Hp is the pressure scale height at the edge of the convective core as given by the Schwarzschild criterion, and alpha(ov) is a free parameter. We find a relation between alpha(ov) and mass that is defined much more clearly than in previous work, and indicates a significant rise up to about 2 solar masses followed by little or no change beyond this mass. No appreciable dependence is seen with evolutionary state at a given mass, or with metallicity at a given mass despite the fact that the stars in our sample span a range of a factor of ten in [Fe/H], from -1.01 to +0.01.
description: 13 pages in two-column format, including figures and tables. Accepted for publication in A&A