cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Strongly disordered Hubbard model in one dimension: spin and orbital infinite randomness and Griffiths phases
Creators: name: Mélin, R.
name: Iglói, F.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We study by the strong disorder renormalization group (RG) method the low-energy properties of the one-dimensional Hubbard model with random-hopping matrix-elements $t_{min} t_{max}$) and to an orbital infinite randomness fixed point for vanishing interactions ($U_{max}/t_{max} \to 0$). To each critical infinite randomness fixed point is connected a Griffiths phase, the correlation length and dynamical exponent of which have well defined asymptotic dependences on the corresponding quantum control parameter. The theoretical predictions for the scaling in the vicinity of the critical points compare well to numerical RG simulations.
description: 9 pages, 7 figures
Work and Technological Innovation in the Retail Sector. The Case of Fast Fashion Stores in Italy
Creators: name: Manzo, Cecilia
name: Fullin, Giovanna
name: Bianconi, Beatrice
Publisher: name: Italian Sociological Review
Year: 2024

description: The impact of technological innovation on employment has been a subject of extensive study, particularly regarding job polarization, where routine, medium-skilled jobs are more likely to be automated compared to high-skilled and manual jobs. However, medium-skilled jobs requiring face-to-face interaction, such as those in the retail sector, are less susceptible to automation. This article examines how technological innovation is transforming the roles of frontline service workers in the retail sector, focusing on sales assistants in the fast fashion industry in Milan.

Retail is not a leading industry in technological innovation, making it a suitable example for studying gradual changes in job roles due to technology. The research investigates how the integration of online sales and digital tools has impacted the work organization and job quality of sales assistants. Despite the rise in online sales, brick-and-mortar stores have not been entirely replaced, but the nature of in-store work has become more complex.

Drawing on three strands of literature—technology’s impact on employment, digitalization and algorithmic management, and job quality—the study uses interviews with workers, managers, and trade unionists and maps recent changes that occurred in fast fashion stores. Findings reveal that technological innovation in retail has made sales assistants’ jobs more demanding but has not necessarily improved job quality or wages, highlighting a need for better training and economic recognition to support these workers through the ongoing transformations.
description: Italian Sociological Review, Vol. 14 No. 3 (2024)
LIKE Open Science Course Seminar 4: Communications Strategies
Creators: name: Clifton, Andrew
Publisher: name: Zenodo
Year: 2020

description: This is the PDF of a seminar in a course on open science, first delivered as part of the Innovative Training Network Lidar Knowledge Europe (ITN-LIKE). The seminar discusses communications strategies in the context of open science. For more information see the seminar notes on Github.
Luttinger Liquid at the Edge of a Graphene Vacuum
Creators: name: Fertig, H. A.
name: Brey, Luis
Publisher: name: arXiv
Year: 2006
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We demonstrate that an undoped two-dimensional carbon plane (graphene) whose bulk is in the integer quantum Hall regime supports a non-chiral Luttinger liquid at an armchair edge. This behavior arises due to the unusual dispersion of the non-interacting edges states, causing a crossing of bands with different valley and spin indices at the edge. We demonstrate that this stabilizes a domain wall structure with a spontaneously ordered phase degree of freedom. This coherent domain wall supports gapless charged excitations, and has a power law tunneling $I-V$ with a non-integral exponent. In proximity to a bulk lead, the edge may undergo a quantum phase transition between the Luttinger liquid phase and a metallic state when the edge confinement is sufficiently strong relative to the interaction energy scale.
description: 4 pages, 3 figures
Media Representation of Pakistani Transgender People in Newspapers’ Blogs Through Corpus Approaches
Creators: name: Zahra, Tehseen
name: Abbas, Akhtar
Publisher: name: Italian Sociological Review
Year: 2024

description: Media (mis)representation of transgender people has become crucial in shaping the perception, attitude and behaviours of the masses towards them all over the world. Pakistani media is not an exception regarding the portrayal of transgender individuals living in Pakistan. The current study focuses on revealing media representation of Pakistani trans people through blogs published in the country. The current study employs corpus approaches to explore this representation of transgender identity by analysing newspapers’ blogs published on the subject (i.e. on transgender people) in Pakistan. The concordance lines of the first ten recurrent content words including transgender, community, people, rights, Pakistan, gender, society, persons, government, and identity from the word list were analysed to explore the themes related to the identity of transgender people in the country. The study found linguistic expressions of transgender apartheid in Pakistan at all levels of the social fabric of the country. However, at the same time discourse of solidarity towards transgender identity was also noticed in the data of the current study. The study proffers an insight to the linguists in general and corpus linguists, in particular, to extend theoretical conceptualization, application of linguistic methods and corpus linguistic techniques to highlight the issues/problems faced by transgender people.
description: Italian Sociological Review, Vol. 14 No. 3 (2024)
Extracting low energy signals from raw LArTPC waveforms using deep learning techniques -- A proof of concept
Creators: name: Uboldi, Lorenzo
name: Ruth, David
name: Andrews, Michael
name: Wang, Michael H. L. S.
name: Wenzel, Hans-Joachim
name: Wu, Wanwei
name: Yang, Tingjun
Publisher: name: arXiv
Year: 2021
Subjects: subject: Instrumentation and Detectors (physics.ins-det)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: We investigate the feasibility of using deep learning techniques, in the form of a one-dimensional convolutional neural network (1D-CNN), for the extraction of signals from the raw waveforms produced by the individual channels of liquid argon time projection chamber (LArTPC) detectors. A minimal generic LArTPC detector model is developed to generate realistic noise and signal waveforms used to train and test the 1D-CNN, and evaluate its performance on low-level signals. We demonstrate that our approach overcomes the inherent shortcomings of traditional cut-based methods by extending sensitivity to signals with ADC values below their imposed thresholds. This approach exhibits great promise in enhancing the capabilities of future generation neutrino experiments like DUNE to carry out their low-energy neutrino physics programs.
Integrability and non-perturbative effects in the AdS/CFT correspondence
Creators: name: Gomez, Cesar
name: Hernandez, Rafael
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We present a non-perturbative resummation of the asymptotic strong-coupling expansion for the dressing phase factor of the AdS_5xS^5 string S-matrix. The non-perturbative resummation provides a general form for the coefficients in the weak-coupling expansion, in agreement with crossing symmetry and transcendentality. The ambiguities of the non-perturbative prescription are discussed together with the similarities with the non-perturbative definition of the c=1 matrix model.
description: 8 pages. Latex
Η αυτοβιογραφία στην Ιταλία του 18ου αιώνα
Creators: name: Βλαχάκη, Σοφία-Παναγιώτα
Publisher: name: Aristotle University of Thessaloniki
Year: 2004
Subjects: Διαφωτισμός
Ρομαντισμός
Αυτοπαρουσίαση
Enlightenment
Romanticism
Self-presentation

description: Σκοπός της έρευνας αυτής είναι η ανάδειξη των χαρακτηριστικών της αυτοβιογραφίας όπως αυτή παρουσιάζεται στην Ιταλία του 18ου αιώνα. Μετά από μια σύντομη αναφορά σε απόψεις σύγχρονων μελετητών για το αυτοβιογραφικό είδος, έτσι ώστε ο αναγνώστης να το γνωρίσει καλύτερα, η έρευνα αναλύει τα αυτοβιογραφικά έργα της εποχής παρέχοντας περισσότερα στοιχεία για αυτοβιογραφίες που έχουν ήδη μελετηθεί στοιχεία για αυτοβιογραφίες για τις οποίες πέρα από το εισαγωγικό σημείωμα του εκδότη δεν υπάρχει μια άλλη εμπερειστατωμένη κριτική και μελέτη. Στη συνέχεια παραθέτονται τα συμπεράσματα που απορρέουν για το αυτοβιογραφικό είδος, ενώ τονίζεται η σημασία του σε σχέση με το πολιτικό, κοινωνικό και πολιτιστικό πλαίσιο της εποχής
description: The purpose of this inquiry is the rending of the caracteristics of autobiography as it is presented in Italy in 18th century. After a short reference on views of modern scholars on the autobiographical form, so as the reader should get to know it better, the inquiry analyses the autobiographical works of the time providing more elements on autobiographies that have been studied less and finally it studies autographies on which, far from the introductory notice of the publisher, there is no other detailed review and study. Furthermore, the conclusions which are drown on the autobiographical form of the time are quoted, while its significance is marked in addition to the political, social cultural environment of the time
Convex optimization with inexact gradients in Hilbert space and applications to elliptic inverse problems
Creators: name: Matyukhin, Vladislav
name: Kabanikhin, Sergey
name: Shishlenin, Maxim
name: Novikov, Nikita
name: Vasin, Artem
name: Gasnikov, Alexander
Publisher: name: Weierstrass Institute
Year: 2021
Subjects: subject: Convex optimization
subject: inexact oracle
subject: inverse and ill-posed problem
subject: gradient method
subject: 90C30
subject: 90C25
subject: 68Q25

description: In this paper we propose the gradient descent type methods to solve convex optimization problems in Hilbert space. We apply it to solve ill-posed Cauchy problem for Poisson equation and make a comparative analysis with Landweber iteration and steepest descent method. The theoretical novelty of the paper consists in the developing of new stopping rule for accelerated gradient methods with inexact gradient (additive noise). Note that up to the moment of stopping the method ``doesn't feel the noise''. But after this moment the noise start to accumulate and the quality of the solution becomes worse for further iterations.
Έρευνες σε "πηγές" των ποιημάτων του Σεφέρη
Creators: name: Θωμαϊδου-Μώρου, Μάρθα
Publisher: name: Aristotle University of Thessaloniki
Year: 2003
Subjects: "Πηγές"
Χριστιανική εικονογραφία
"Sources"
Christian iconography

description: Η εργασία αυτή αποτελείται από δύο μέρη. Στο πρώτο μέρος, ανιχνεύονται "πηγές" από τη Βίβλο και από τη χριστιανική εικονογραφία, και διερευνάται ο τρόπος ενσωμάτωσης και η λειτουργία τους μέσα στην ποίηση του Σεφέρη. Στο δεύτερο μέρος, ανιχνεύονται "πηγές" από την ποίηση του Καρυωτάκη και του Παλαμά, και διερευνάται ο διαλογικός τρόπος χρήσης τους, η "συνομιλία" του Σεφέρη με τους δύο αυτούς ποιητές. Η αντιμετώπιση του θέματος των "πηγών" στηρίζεται στις απόψεις του Σεφέρη σχετικά με το θέμα αυτό, οι οποίες διατυπώνονται σε κείμενά του δοκιμιακά, κυρίως, αλλά και στα ημερολόγιά του. Οι πιο χαρακτηριστικές σχετικές απόψεις του αποκρυσταλλώνονται στην "Εισαγωγή στον Θ.Σ. Έλιοτ". Στο πρώτο μέρος, διαπιστώνεται η μη καθαρά θρησκευτική, η "μυθολογική" χρήση των "πηγών". Στο δεύτερο μέρος, το ότι οι "συνομιλίες" με ομότεχνους εντάσσονται μέσα σε ένα πλαίσιο ποιητικής "αλληλεγγύης", ή μέσα σε ένα πλαίσιο κοινού ιστορικού αισθήματος. Και στα δύο μέρη, φωτίζεται η ερμηνευτική σημασία των "πηγών", μέσα στα ποιήματα στα οποία βρίσκονται.
description: This study consists of two parts. In the first part, we research "sources" from the Bible as well as from christian iconography, and we examine the way they are incorporated, and their function, in Seferis' poetry. in the second part we research "sources" both from Karyotakis' and Palamas' poetry and we explore their "dialogical" way of use, Seferis' "conversation" with these two poets. The treatment of the issue concerning the "sources" is based upon Seferis' ideas about this theme, which ideas are expressed mostly in his essays and in his journal as well. His most characteristic relative opinions crystallize in his essay "Introduction to T.S. Eliot". In the first part of the study, not areligious but a "mythical" use of the "sources" is established. In the second part, it is concluded that Seferis' "dialogue" with other poetsis placed in the "context" of a poetic "solidarity", or in the "context" of a common historical sentiment. In both parts, the interpretative importance of the "sources" to the poems that include them is enlightened.
Electronic Properties of the Semiconductor RuIn$_3$
Creators: name: Bogdanov, D.
name: Winzer, K.
name: Nekrasov, I. A.
name: Pruschke, T.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Temperature dependent measurements of the resistivity on RuIn$_3$ single crystals show a semiconducting behaviour, in contrast to previously published results. In the high temperature range the semiconducting gap was measured to be $0.4-0.5$eV. We observe an anisotropy of the resistivity along [110] and [001] orientations of the tetragonal single crystals. At low temperatures two activation energies of impurities were estimated to 1meV and 10meV. The temperature dependence of the specific heat and the band structure calculations provide also a semiconducting behaviour of RuIn$_3$.
Securing the Network for a Smart Bracelet System
Creators: name: Marin, Iuliana
name: Goga, Nicolae
Publisher: name: arXiv
Year: 2021
Subjects: subject: Computers and Society (cs.CY)
subject: FOS: Computer and information sciences

description: Digital instruments play a vital role in our daily life. It is a routine to produce business papers, watch the news program, write articles and blogs, manage healthcare systems, to purchase online, to send messages and all this is processed by making observations and then manipulating, receiving and availing the diverse data. This electronic data provides the foundation of real time data. All this transmission of data needs to be secured. Security is essential for healthcare systems as the present one where the blood pressure recordings provided by the smart bracelet are sent to the user's mobile phone via Bluetooth. The bracelet monitors the pregnant women, but also other users who wish to have their blood pressure under control. The system's server analyses the recordings and announces the user, as well as the associated persons to the user in case of an emergency. The doctors, the medical staff, user and user's family and caregivers have access to the health recordings belonging to the monitored user. Security is a main feature of the electronic healthcare system based on the smart bracelet.
Modeling the (upper) solar atmosphere including the magnetic field
Creators: name: Peter, H.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: The atmosphere of the Sun is highly structured and dynamic in nature. From the photosphere and chromosphere into the transition region and the corona plasma-$β$ changes from above to below one, i.e. while in the lower atmosphere the energy density of the plasma dominates, in the upper atmosphere the magnetic field plays the governing role -- one might speak of a ``magnetic transition''. Therefore the dynamics of the overshooting convection in the photosphere, the granulation, is shuffling the magnetic field around in the photosphere. This leads not only to a (re-)structuring of the magnetic field in the upper atmosphere, but induces also the dynamic reaction of the coronal plasma e.g. due to reconnection events. Therefore the (complex) structure and the interaction of various magnetic patches is crucial to understand the structure, dynamics and heating of coronal plasma as well as its acceleration into the solar wind. The present article will emphasize the need for three-dimensional modeling accounting for the complexity of the solar atmosphere to understand these processes. Some advances on 3D modeling of the upper solar atmosphere in magnetically closed as well as open regions will be presented together with diagnostic tools to compare these models to observations. This highlights the recent success of these models which in many respects closely match the observations.
description: 14 pages, 7 figures, accepted for publication in Adv. Space Res
Coevolutionary dynamics in large, but finite populations
Creators: name: Traulsen, Arne
name: Claussen, Jens Christian
name: Hauert, Christoph
Publisher: name: arXiv
Year: 2006
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: Coevolving and competing species or game-theoretic strategies exhibit rich and complex dynamics for which a general theoretical framework based on finite populations is still lacking. Recently, an explicit mean-field description in the form of a Fokker-Planck equation was derived for frequency-dependent selection with two strategies in finite populations based on microscopic processes [A.Traulsen, J.C. Claussen, and C.Hauert, Phys. Rev. Lett. 95, 238701 (2005)]. Here we generalize this approach in a twofold way: First, we extend the framework to an arbitrary number of strategies and second, we allow for mutations in the evolutionary process. The deterministic limit of infinite population size of the frequency dependent Moran process yields the adjusted replicator-mutator equation, which describes the combined effect of selection and mutation. For finite populations, we provide an extension taking random drift into account. In the limit of neutral selection, i.e. whenever the process is determined by random drift and mutations, the stationary strategy distribution is derived. This distribution forms the background for the coevolutionary process. In particular, a critical mutation rate $u_c$ is obtained separating two scenarios: above $u_c$ the population predominantly consists of a mixture of strategies whereas below $u_c$ the population tends to be in homogenous states. For one of the fundamental problems in evolutionary biology, the evolution of cooperation under Darwinian selection, we demonstrate that the analytical framework provides excellent approximations to individual based simulations even for rather small population sizes. This approach complements simulation results and provides a deeper, systematic understanding of coevolutionary dynamics.
description: 8 pages, 4 figs included
Matching complexes of $\bf 3 \times n$ grid graphs
Creators: name: Goyal, Shuchita
name: Shukla, Samir
name: Singh, Anurag
Publisher: name: arXiv
Year: 2021
Subjects: subject: Combinatorics (math.CO)
subject: Algebraic Topology (math.AT)
subject: FOS: Mathematics
subject: 05E45, 55P15

description: The matching complex of a graph $G$ is a simplicial complex whose simplices are matchings in $G$. In the last few years the matching complexes of grid graphs have gained much attention among the topological combinatorists. In 2017, Braun and Hough obtained homological results related to the matching complexes of $2 \times n$ grid graphs. Further in 2019, Matsushita showed that the matching complexes of $2 \times n$ grid graphs are homotopy equivalent to a wedge of spheres. In this article we prove that the matching complexes of $3\times n$ grid graphs are homotopy equivalent to a wedge of spheres. We also give the comprehensive list of the dimensions of spheres appearing in the wedge.
description: 21 pages, many figures
Monte Carlo Simulations of Ultrathin Magnetic Dots
Creators: name: Rapini, M.
name: Dias, R. A.
name: Landau, D. P.
name: Costa, B. V.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Computational Physics (physics.comp-ph)
subject: General Physics (physics.gen-ph)
subject: FOS: Physical sciences

description: In this work we study the thermodynamic properties of ultrathin ferromagnetic dots using Monte Carlo simulations. We investigate the vortex density as a function of the temperature and the vortex structure in monolayer dots with perpendicular anisotropy and long-range dipole interaction. The interplay between these two terms in the hamiltonian leads to an interesting behavior of the thermodynamic quantities as well as the vortex density.
description: 10 figures
High Resolution X-ray Spectroscopy of T Tauri Stars in the Taurus-Auriga Complex
Creators: name: Telleschi, A.
name: Guedel, M.
name: Briggs, K. R.
name: Audard, M.
name: Scelsi, L.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Differences have been reported between the X-ray emission of accreting and non-accreting stars. Some observations have suggested that accretion shocks could be responsible for part of the X-ray emission in Classical T Tauri stars (CTTS). We present high-resolution X-ray spectroscopy of nine pre-main sequence stars in order to test the proposed spectroscopic differences between accreting and non-accreting pre-main sequence stars. We use X-ray spectroscopy from the XMM-Newton Reflection Grating Spectrometers and the EPIC instruments. We interpret the spectra using optically thin thermal models with variable abundances, together with an absorption column density. For BP Tau and AB Aur we derive electron densities from the O VII triplets. Using the O VII/O VIII count ratios as a diagnostic for cool plasma, we find that CTTS display a soft excess (with equivalent electron temperatures of ~ 2.5-3 MK) when compared with WTTS or zero-age main-sequence stars. Although the O VII triplet in BP Tau is consistent with a high electron density (3.4 x 10^11 cm^-3), we find a low density for the accreting Herbig star AB Aur (n_e < 10^10 cm^-3). The element abundances of accreting and non-accreting stars are similar. The Ne abundance is found to be high (4-6 times the Fe abundance) in all K and M-type stars. In contrast, for the three G-type stars (SU Aur, HD 283572, and HP Tau/G2), we find an enhanced Fe abundance (0.4-0.8 times solar photospheric values) compared to later-type stars. Adding the results from our sample to former high-resolution studies of T Tauri stars, we find a soft excess in all accreting stars, but in none of the non-accretors. On the other hand, high electron density and high Ne/Fe abundance ratios do not seem to be present in all accreting pre-main sequence stars.
description: 22 pages, 9 figures, to be published in A&A, to appear in a special section/issue dedicated to the XMM-Newton Extended Survey of the Taurus Molecular Cloud (XEST)
Massless polarized particle and Faraday rotation of light in the Schwarzschild spacetime
Creators: name: Deriglazov, Alexei A.
Publisher: name: arXiv
Year: 2021
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: We present the manifestly covariant Lagrangian of a massless polarized particle, that implies all dynamic and algebraic equations as the conditions of extreme of this variational problem. The model allows for minimal interaction with a gravitational field, leading to the equations, coinciding with Maxwell equations in the geometrical optics approximation. The model allows also a wide class of non minimal interactions, which suggests an alternative way to study the electromagnetic radiation beyond the leading order of geometrical optics. As a specific example, we construct a curvature-dependent interaction in Schwarzschild spacetime, predicting the Faraday rotation of polarization plane, linearly dependent on the wave frequency. As a result, the Schwarzschild spacetime generates a kind of angular rainbow of light: waves of different frequencies, initially linearly-polarized in one direction, acquire different orientations of their polarization planes when propagate along the same ray.
description: 13+7 pages, misprints corrected, minor edits
Extreme dependence for multivariate data
Creators: name: Bosc, Damien
name: Galichon, Alfred
Publisher: name: arXiv
Year: 2021
Subjects: subject: Econometrics (econ.EM)
subject: FOS: Economics and business

description: This article proposes a generalized notion of extreme multivariate dependence between two random vectors which relies on the extremality of the cross-covariance matrix between these two vectors. Using a partial ordering on the cross-covariance matrices, we also generalize the notion of positive upper dependence. We then proposes a means to quantify the strength of the dependence between two given multivariate series and to increase this strength while preserving the marginal distributions. This allows for the design of stress-tests of the dependence between two sets of financial variables, that can be useful in portfolio management or derivatives pricing.
description: 20 pages, 8 figures
Neural Decision Boundaries for Maximal Information Transmission
Creators: name: Sharpee, Tatyana
name: Bialek, William
Publisher: name: arXiv
Year: 2007
Subjects: subject: Neurons and Cognition (q-bio.NC)
subject: FOS: Biological sciences

description: We consider here how to separate multidimensional signals into two categories, such that the binary decision transmits the maximum possible information transmitted about those signals. Our motivation comes from the nervous system, where neurons process multidimensional signals into a binary sequence of responses (spikes). In a small noise limit, we derive a general equation for the decision boundary that locally relates its curvature to the probability distribution of inputs. We show that for Gaussian inputs the optimal boundaries are planar, but for non-Gaussian inputs the curvature is nonzero. As an example, we consider exponentially distributed inputs, which are known to approximate a variety of signals from natural environment.
description: 5 pages, 3 figures
Η επίδραση της σχέσης μεταξύ οικονομικής βοήθειας και εξυπηρέτησης του εξωτερικού χρέους στην ανάπτυξη μιας αναπτυσσόμενης χώρας: η περίπτωση της Νιγηρίας
Creators: name: Tijani Mohammed, Shedu
Publisher: name: Aristotle University of Thessaloniki
Year: 2003
Subjects: Εξυπηρέτηση του εξωτερικού χρέους
Οικονομική ανάπτυξη
Αιτιότητα
External debt servising
Economic growth
Causality

description: Ο αντικειμενικός σκοπός της παρούσης εργασίας είναι η εξέταση της σχέσης μεταξύ της οικονομικής βοήθειας και της εξυπηρέτησης του εξωτερικού χρέους και της επίδρασης που η σχέση αυτή προκαλεί στη διαδικασία οικονομικής ανάπτυξης της Νιγηριανής οικονομίας. Με τη χρήση της μεθόδου VAR εξετάζεται η επίδραση της οικονομικής βοήθειας στην ανάπτυξη της Νιγηριανής οικονομίας. Διατυπώνονται καταρχήν οι έλεγχοι α)της αιτιότητας κατά Granger και β)της στασιμότητας και των διαρθρωτικών αλλαγών στις βασικές χρονολογικές σειρές. Ο έλεγχος κατά Granger για τη φύση της σχέσης μεταξύ της οικονομικής βοήθειας που δέχεται η Νιγηρία και της εξυπηρέτησης του εν συνεχεία δημιουργούμενου χρέους της, έδειξε ότι υπάρχει μια αμφίδρομη αιτιώδης σχέση μεταξύ τους. Αυτό σημαίνει ότι η εισροή της οικονομικής βοήθειας οδήγησε στην εμφάνιση του προβλήματος της εξυπηρέτησης του εξωτερικού χρέους, η οποία με τη σειρά της δημιουργεί την ανάγκη για ολοένα και περισσότερη οικονομική βοήθεια, η οποία όμως χρησιμοποιείται για την εξυπηρέτηση του εξωτερικού χρέους και όχι για την ανάληψη παραγωγικών επενδύσεων.
description: The objective aim of this study is to examine the relation between foreign aid and external debt servicing and the impact which this relation has on the process of development of the Nigerian economy. With the use of the method of VAR the impact of foreign aid on the development of the Nigerian economy is examined: a)Granger causality test and b)tests for stationarity and structural breaks in the time series. Granger causality test of the nature of the relation between foreign aid accepters by Nigeria and the servicing of external debt which enslie, showed that there is a casual feedback relation between them. This means that the inflow of aids leads to the emergence of external debt service problems, which in its turn create the need for more aid which however is used for servicing previous debts and not for financing additional productive investments.
Gravitational effects of cosmic strings
Creators: name: Vollick, Daniel
Publisher: name: University of British Columbia
Year: 2009

description: Cosmic strings are line-like distributions of energy which may have formed in the early universe. Recent simulations of the evolution of cosmic string networks show that strings have a significant amount of small scale structure (i.e. wiggles). In this thesis we will examine some of the gravitational effects produced by wiggly cosmic strings. One intriguing possibility is that cosmic strings produced the density perturbations which triggered the formation of galaxies and large scale structure. Calculations by others which neglect the wiggles suggest that this scenario is ruled out. Using the Zel’dovich approximation and taking the wiggles into account I found that the wakes produced by the strings in cold dark matter can account for the observed large scale structure of the universe. Using the Gilbert equation I found that the size of the structure produced in hot dark matter is smaller but comparable to the size of the observed large scale structure. I also found that the wiggles can fragment the wakes into pieces which have the mass of a galaxy. One of the interesting observational effects of cosmic strings is the production of double images through gravitational lensing. The gravitational field of a wiggly string differs from the field of a straight string in that the curvature tensor outside a straight string is zero, whereas the curvature tensor diverges as one approaches a wiggly string. Could this make a significant observational difference? To examine this I calculated the effect of a wave pulse on the images of objects located behind the string and found that differences exist, but are small.
Nature of excitations of the 5/2 fractional quantum Hall effect
Creators: name: Toke, Csaba
name: Regnault, Nicolas
name: Jain, Jainendra K.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: It is shown, with the help of exact diagonalization studies on systems with up to sixteen electrons, in the presence of up to two delta function impurities, that the Pfaffian model is inadequate for the actual quasiholes and quasiparticles of the 5/2 fractional quantum Hall effect. Implications for non-Abelian statistics are discussed.
description: 4 pages, 2 figures
Kinetically-balanced Gaussian Basis Set Approach to Relativistic Compton Profiles of Atoms
Creators: name: Jaiswal, Prerit
name: Shukla, Alok
Publisher: name: arXiv
Year: 2007
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Atomic Compton profiles (CPs) are a very important property which provide us information about the momentum distribution of atomic electrons. Therefore, for CPs of heavy atoms, relativistic effects are expected to be important, warranting a relativistic treatment of the problem. In this paper, we present an efficient approach aimed at ab initio calculations of atomic CPs within a Dirac-Hartree-Fock (DHF) formalism, employing kinetically-balanced Gaussian basis functions. The approach is used to compute the CPs of noble gases ranging from He to Rn, and the results have been compared to the experimental and other theoretical data, wherever possible. The influence of the quality of the basis set on the calculated CPs has also been systematically investigated.
description: 31 pages, 12 figures
Laboratory Plasma Dynamos, Astrophysical Dynamos, and Magnetic Helicity Evolution
Creators: name: Blackman, Eric G.
name: Ji, Hantao
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: Plasma Physics (physics.plasm-ph)
subject: FOS: Physical sciences

description: The term ``dynamo'' means different things to the laboratory fusion plasma and astrophysical plasma communities. To alleviate the resulting confusion and to facilitate interdisciplinary progress, we pinpoint conceptual differences and similarities between laboratory plasma dynamos and astrophysical dynamos. We can divide dynamos into three types: 1. magnetically dominated helical dynamos which sustain a large scale magnetic field against resistive decay and drive the magnetic geometry toward the lowest energy state, 2. flow-driven helical dynamos which amplify or sustain large scale magnetic fields in an otherwise turbulent flow, and 3. flow-driven nonhelical dynamos which amplify fields on scales at or below the driving turbulence. We discuss how all three types occur in astrophysics whereas plasma confinement device dynamos are of the first type. Type 3 dynamos requires no magnetic or kinetic helicity of any kind. Focusing on type 1 and 2 dynamos, we show how different limits of a unified set of equations for magnetic helicity evolution reveal both types. We explicitly describe a steady-state example of a type 1 dynamo, and three examples of type 2 dynamos: (i) closed volume and time dependent; (ii) steady-state with open boundaries; (iii) time dependent with open boundaries.
description: accepted by MNRAS
Γεωμετρικοί συσχετισμοί και στατική αντίληψη στις μεγάλες θολωτές κατασκευές της ρωμαϊκής και βυζαντινής περιόδου
Creators: name: Γουρίδης, Αθανάσιος
Publisher: name: Aristotle University of Thessaloniki
Year: 2003
Subjects: Γραμμική θεωρία
Θολωτές κατασκευές
Κατασκευές όγκου
Κατασκευές μορφής
Γεωμετρικοί συσχετισμοί
Linear theory
Structures of form
Structures of volume
Geometrical correlations

description: Η διατριβή τεκμηριώνει τη γένεση της δομικής μηχανικής ως μέρους της μηχανικής ήδη από τους εληνιστικούς χρόνους και τη θεωρητική στήριξη της κτιριοδομίας κατά τους ιστορικούς χρόνους. Δείχνει τη δομική φύση της διασιασιολόγησης και διακρίνει τις κατασκευές σε δύο τύπους, όγκου και μορφής. Τέλος διερευνά συστηματικά την εξέλιξη ιών μαθηματικών, της μηχανικής, της τεχνικής σχεδίασης σε σχέση με τις θολωτές κατασκευές από την προϊστορία έως τον 19ο αιώνα
description: The dissertation proves the birth of structural mechanics as part of mechanics already from hellenistic period of the theoretical support of mansonry building during historical times. If shows the structural nature of dimensioning and discerns buildings in two categories, these of volume & those of forms. Finally it researches systematically the evalution of mathematics, mechanics, technical drawing in relationship to domed structures from prehistoric times to the 19th. century
Associated molecular and atomic clouds with X-ray shell of superbubble 30 Doradus C in the LMC
Creators: name: Yamane, Y.
name: Sano, H.
name: Filipovic, M. D.
name: Tokuda, K.
name: Fujii, K.
name: Babazaki, Y.
name: Mitsuishi, I.
name: Inoue, T.
name: Aharonian, F.
name: Inaba, T.
name: Inutsuka, S.
name: Maxted, N.
name: Mizuno, N.
name: Onishi, T.
name: Rowell, G.
name: Tsuge, K.
name: Voisin, F.
name: Yoshiike, S.
name: Fukuda, T.
name: Kawamura, A.
name: Bamba, A.
name: Tachihara, K.
name: Fukui, Y.
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: 30 Doradus C is a superbubble which emits the brightest nonthermal X- and TeV gamma-rays in the Local Group. In order to explore detailed connection between the high energy radiation and the interstellar medium, we have carried out new CO and HI observations using the Atacama Large Millimeter$/$Submillimeter Array (ALMA), Atacama Submillimeter Telescope Experiment, and the Australia Telescope Compact Array with resolutions of up to 3 pc. The ALMA data of $^{12}$CO($J$ = 1-0) emission revealed 23 molecular clouds with the typical diameters of $\sim$6-12 pc and masses of $\sim$600-10000 $M_{\odot}$. The comparison with the X-rays of $XMM$-$Newton$ at $\sim$3 pc resolution shows that X-rays are enhanced toward these clouds. The CO data were combined with the HI to estimate the total interstellar protons. Comparison of the interstellar proton column density and the X-rays revealed that the X-rays are enhanced with the total proton. These are most likely due to the shock-cloud interaction modeled by the magnetohydrodynamical simulations (Inoue et al. 2012, ApJ, 744, 71). Further, we note a trend that the X-ray photon index varies with distance from the center of the high-mass star cluster, suggesting that the cosmic-ray electrons are accelerated by one or multiple supernovae in the cluster. Based on these results we discuss the role of the interstellar medium in cosmic-ray particle acceleration.
description: 20 pages, 14 figures, 3 tables, accepted for publication in The Astrophysical Journal
Σκέδαση των επιφανειακών κυμάτων στα επιφανειακά στρώματα του φλοιού της γης στον ευρύτερο χώρο του Αιγαίου
Creators: name: Καραγιάννη, Ελένη Ε.
Publisher: name: Aristotle University of Thessaloniki
Year: 2002
Subjects: Surface waves
Dispresion of surface waves
Hedgehog inversion
Επιφανειακά κύματα
Σκέδαση των επιφανειακών κυμάτων
Τομογραφία των επιφανειακών κυμάτων
Αντιστροφή Hedgehog

description: Οι ταχύτητες ομάδας των κυμάτων Rayleigh ήταν τα αρχικά δεδομένα που χρησιμοποιήθηκαν στην εκπόνηση της διατριβής αυτής. Αρχικά συλλέχθησαν οι σεισμοί (Mw>/4.0) που σημειώθηκαν στον ελληνικό χώρο και για κάθε διαδρομή μεταξύ σεισμού-σταθμού υπολογίστηκαν οι ταχύτητες ομάδες των κυμάτων Rayleigh. Οι καμπύλες αυτές χρησιμοποιήθηκαν κατόπιν για την παραγωγή των δισδιάστατων χαρτών μεταβολής της ταχύτητας ομάδας για διάφορες τιμές περιόδου. Από τους χάρτες αυτούς φαίνεται η διαφορά της δομής μεταξύ ηπειρωτικής Ελλάδας και θάλασσας του Αιγαίου. οι τοπικές καμπύλες σκέδασης όπως προέκυψαν από τους παραπάνω χάρτες χρησιμοποιήθηκαν για την παραγωγή 10 μοντέλων με την χρήση της αντιστροφής Hedgehog για περίπου 70 σημεία στον ελληνικό χώρο. Χάρτης μεταβολής του βάθους της Moho και μεταβολές της ταχύτητας των S κυμάτων για διάφορα βάθη προέκυψαν
description: The group velocity of the Rayleigh waves were used as initial data in this thesis. We selected earthquakes Mw>/4.0 occured in the Greek area and for each path epicenter-statics an observed group velocity was estimated. Using the curves 2D maps of group velocities were estimated and show the difference in the structure between the continental Greece and the sea of the Aegean. The local dispersion curves as derived from the afromentioned maps were inverted using the Hedgehog method and 1D models of S wave velocity versus depth were derived for around 70 points in the study area. Maps of the moho depth discontinuity and S waves velocity for different depths are shown
Integral protein and cholesterol in model membranes : a ²H NMR study
Creators: name: Nezil, Frank Arthur
Publisher: name: University of British Columbia
Year: 2008

description: Deuterium (²H) nuclear magnetic resonance (NMR) is used to study bilayer hydrophobic thickness and thickness expansivity in La phase lipid bilayer membranes containing combinations of POPC , cholesterol, and synthetic amphiphillic polypeptides of different hydrophobic lengths. Subsequent analysis relates ²H NMR thickness expansivity measurements to micromechanical measurements of the area expansivity, άA. Model membrane area expansivity to date has seldom been considered i n typical analyses of NMR data. We study a case, using ²H and 31P NMR , in which considerations of άA are central: spontaneous vesiculation i n model membranes composed of POPC and POPS , with and without cholesterol. Subsequent freeze-fracture electron microscopy confirms that membrane eruptions occur in response to positive temperature changes and upon addition of, for instance, myelin basic protein (MBP) . Eruptions are shown to occur more readily in the presence of cholesterol. Estimations of άA based upon NMR data in these systems is found to be in agreement with micromechanical measurements of άA. Orientation-dependent spin-spin (T2) relaxation in some of the above systems potentially confounds the interpretation of apparent thickness changes as being due to inclusion of integral polypeptides. A procedure is outlined which allows empirical correction of distorsion in inhomogeneously broadened NMR spectra due to orientation-dependent relaxation processes. This is then applied to data of previous studies, thereby ruling out T2 distorsion as an artifactuaL "cause" of previously described changes in bilayer hydrophobic thickness. The method is then used to suggest some directions for future study.
An Ising-Like model for protein mechanical unfolding
Creators: name: Imparato, A.
name: Pelizzola, A.
name: Zamparo, M.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: Biomolecules (q-bio.BM)
subject: FOS: Physical sciences
subject: FOS: Biological sciences

description: The mechanical unfolding of proteins is investigated by extending the Wako-Saito-Munoz-Eaton model, a simplified protein model with binary degrees of freedom, which has proved successful in describing the kinetics of protein folding. Such a model is generalized by including the effect of an external force, and its thermodynamics turns out to be exactly solvable. We consider two molecules, the 27th immunoglobulin domain of titin and protein PIN1. In the case of titin we determine equilibrium force-extension curves and study nonequilibrium phenomena in the frameworks of dynamic loading and force clamp protocols, verifying theoretical laws and finding the position of the kinetic barrier which hinders the unfolding of the molecule. The PIN1 molecule is used to check the possibility of computing the free energy landscape as a function of the molecule length by means of an extended form of the Jarzynski equality.
description: 4 pages + appendix
Ανάπτυξη αλγορίθμου ανάλυσης της ελαστο-πλαστικής συζευγμένης στερεοποίησης με τη μέθοδο πεπερασμένων στοιχείων: εφαρμογή στις περιπτώσεις ανοικτών και υπόγειων εκσκαφών
Creators: name: Δράκος, Στέφανος
Publisher: name: Aristotle University of Thessaloniki
Year: 2003
Subjects: Συζευγμένη ελαστο-πλαστικη στερεοποίηση
Γεωτεχνική μηχανική
Σήραγγες σε αστικό περιβάλλον
Elasto-plastic coupled consolidation analysis
Geotechnical engineering
Tunneling in urban environment

description: Στα πλαίσια της παρούσας διατριβής αναπτύχθηκε ένας νέος κώδικας πεπερασμένων στοιχείων ελαστοπλαστικής συζευγμένης στερεοποίησης. Στον κώδικα προσαρμόσθηκε κατάλληλα αλγόριθμος εκσκαφής. Ο κώδικας εφαρμόσθηκε με επιτυχία στην περίπτωση της προσομοίωσης της σήραγγας στο Μετρό της Αθήνας.
description: A new finite element algorithm of elast-plastic couple consolidation have been developed. The algorithm can solve the problem at the open and underground excavation. A special application of the algorithm, in the case of the Athens Metro, has presented.
Robust nanopatterning by laser-induced dewetting of metal nanofilms
Creators: name: Favazza, Christopher
name: Kalyanaraman, Ramki
name: Sureshkumar, Radhakrishna
Publisher: name: arXiv
Year: 2006
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We have observed nanopattern formation with robust and controllable spatial ordering by laser-induced dewetting in nanoscopic metal films. Pattern evolution in Co film of thickness 1\leq h\leq8 nm on SiO_{2} was achieved under multiple pulse irradiation using a 9 ns pulse laser. Dewetting leads to the formation of cellular patterns which evolve into polygons that eventually break up into nanoparticles with monomodal size distribution and short range ordering in nearest-neighbour spacing R. Spatial ordering was attributed to a hydrodynamic thin film instability and resulted in a predictable variation of R and particle diameter D with h. The length scales R and D were found to be independent of the laser energy. These results suggest that spatially ordered metal nanoparticles can be robustly assembled by laser-induced dewetting.
Non-Hermitian gauge field theories and BPS limits
Creators: name: Fring, Andreas
name: Taira, Takanobu
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: Exactly Solvable and Integrable Systems (nlin.SI)
subject: FOS: Physical sciences

description: We present an overview of some key results obtained in a recent series devoted to non-Hermitian quantum field theories for which we systematically modify the underlying symmetries. Particular attention is placed on the interplay between the continuous symmetry group that we alter from global to local, from Abelian to non-Abelian, from rank one to generic rank N, and the discrete anti-linear modified CPT-symmetries. The presence of the latter guarantees the reality of the mass spectrum in a certain parameter regime. We investigate the extension of Goldstone's theorem and the Higgs mechanism, which we demonstrate to work in the conventional fashion in the CPT symmetric regime, but which needs to be modified technically at the standard exceptional points of the mass spectrum and entirely fails at what we refer to as zero exceptional points as well as in the broken CPT-symmetric regime. In the full non-Hermitian non-Abelian gauge theory we identify the t'Hooft-Polyakov monopoles by means of a fourfold Bogomol'nyi-Prasad-Sommerfield (BPS) limit. We investigate this limit further for other types of non-Hermitian field theories in 1+1 dimensions that possess complex super-exponential and inverse hyperbolic kink/anti-kink solutions and for 3+1 dimensional Skyrme models for which we find new types of complex solutions, that all have real energies due to the presence of different types of CPT-symmetries.
description: 24 pages, 6 figures, Contribution to the proceedings in the Journal of Physics: Conference Series (IoP Publishing)
Crystal Shapes and Phase Equilibria: A Common Mathematical Basis
Creators: name: Cahn, J. W.
name: Carter, W. C.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: Geometrical constructions, such as the tangent construction on the molar free energy for determining whether a particular composition of a solution, is stable, are related to similar tangent constructions on the orientation-dependent interfacial energy for determining stable interface orientations and on the orientation dependence of the crystal growth rate which tests whether a particular orientation appears on a growing crystal. Subtle differences in the geometric constructions for the three fields arise from the choice of a metric (unit of measure). Using results from studies of extensive and convex functions we demonstrate that there is a common mathematical structure for these three disparate topics, and use this to find new uses for well-known graphical methods for all three topics. Thus the use of chemical potentials for solution thermodynamics is very similar to known vector formulations for surface thermodynamics, and the method of characteristics which tracks the interfaces of growing crystals; the Gibbs-Duhem equation is analogous to the Cahn-Hoffman equation. The Wulff construction for equilibrium crystal shapes can be modified to construct a ``phase shape'' from solution free energies that is a potentially useful method of numerical calculations of phase diagrams from known thermodynamical data.
description: 29 pages, 4 figures, 1 table