cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Residual stresses and shear-induced overaging in boehmite gels
Creators: name: Sudreau, Iana
name: Auxois, Mathilde
name: Servel, Marion
name: Lécolier, Éric
name: Manneville, Sébastien
name: Divoux, Thibaut
Publisher: name: arXiv
Year: 2022
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: Materials Science (cond-mat.mtrl-sci)
subject: Applied Physics (physics.app-ph)
subject: FOS: Physical sciences

description: Colloidal gels respond like soft solids at rest, whereas they flow like liquids under external shear. Starting from a fluidized state under an applied shear rate $\dotγ_{p}$, abrupt flow cessation triggers a liquid-to-solid transition during which the stress relaxes towards a so-called \textit{residual stress} $σ_{\rm res}$ that tallies a macroscopic signature of previous shear history. Here, we report on the liquid-to-solid transition in gels of boehmite, an aluminum oxide, that shows a remarkable non-monotonic stress relaxation towards a residual stress $σ_{\rm res}(\dotγ_{p})$ characterized by a dual behavior relative to a critical value $\dotγ_{c}$ of the shear rate $\dotγ_{p}$. Following shear at $\dotγ_{p}>\dotγ_{c}$, the gel obtained upon flow cessation is insensitive to shear history, and the residual stress is negligible. However, for $\dotγ_{p}<\dotγ_{c}$, the gel encodes some memory of the shear history, and $σ_{\rm res}$ increases for decreasing shear rate, directly contributing to reinforcing the gel viscoelastic properties. Moreover, we show that both $σ_{\rm res}$ and the gel viscoelastic properties increase logarithmically with the strain accumulated during the shear period preceding flow cessation. Such a shear-induced "overaging" phenomenon bears great potential for tuning the rheological properties of colloidal gels.
description: 5 pages, 4 figures
Measuring the outlet state of a bubble column humidifier
Creators: name: Patel, Rishi
Publisher: name: No Publisher Supplied
Year: 2023

description: The issue of water scarcity in rural areas has become a pressing concern, and the humidification-dehumidification process (HDH) for desalination has been identified as a promising solution. Researchers are exploring various methods of improving it’s performance. Previous studies have investigated packed bed humidifiers and spray towers, but recent research has highlighted the potential of using bubble column humidifiers for HDH process. Bubble column humidifiers offer enhanced heat and mass transfer, as well as low maintenance, which makes them an attractive option for this application. Despite their widespread use in many industrial processes, there has been limited research done on the performance of the bubble column humidifier. In many applications, the outlet state of humidifier is unknown and estimated which can lead to equipment damage. For example, if the humidity is too high, it can cause corrosion or rust on metal equipment. To address this problem, a twin tower design with a metering pump is proposed in this thesis. Where the one column is used as a bubble column humidifier and the other column, with less fluctuation, is used to measure the water mass transfer rate during the process. This water mass transfer rate is used to accurately estimate the outlet state of air. In addition, bubble column performance was studied with various inlet air mass flow rates and sparger designs. From the results, it was determined that a sparger with the small diameter holes increases the inter facial area between the liquid and gas phases, which leads to higher water mass transfer. In addition, some pulsation in the water was observed when air flow exits the sparger at lower flow rates. It was also determined that increasing the air mass flow rate causes the bubble column to become more turbulent, which aids in obtaining higher water mass transfer rates and therefore more humid air at the outlet.
Early science with the murchison widefield array : from the moon to the nearest radio galaxies
Creators: name: McKinley, Benjamin
Publisher: name: The Australian National University
Year: 2014
Subjects: subject: Radio interferometers Australia Western Australia
subject: Radio telescopes Australia Western Australia
subject: Radio astronomy

description: This thesis reports on new scientific results gleaned from test observations of well-known astronomical sources with the Murchison Widefield Array (MWA) telescope. Presented are three self-contained papers that demonstrate the capabilities of this recently commissioned radio interferometer array and provide new insights into the astrophysics of the Moon, Centaurus A and Fornax A at low frequencies. One of the main scientific goals of the MWA is the detection of the redshifted 21-cm line of neutral hydrogen from the epoch of reionization (EoR). To investigate the possibility of using the Moon as a calibration source for EoR detection and to test novel observing modes for the MWA, the Moon was observed over a frequency range of 80-170 MHz with the MWA 32-tile prototype. The observations show that the Moon's radio emission is as expected for a cool thermally emitting body, but that the spectrum is corrupted by reflected transmissions from Earth. In particular, the observed flux density of the Moon abruptly increases in the internationally recognized frequency modulated (FM) radio band. The implications for EoR detection using the Moon as a spectrally smooth reference source are discussed and the flux density of the Moon in the FM radio band is used to estimate the Earth's radio leakage and its potential for detection by an extraterrestrial race. Observations of our closest neighbouring radio galaxy, Centaurus A, were made at 118 MHz with the MWA 32-tile prototype. The resulting images demonstrated the widefield imaging capabilities of the MWA and provided the first evidence in total intensity for a southern counterpart to the well-known northern middle lobe of Centaurus A. A detailed spectral analysis of the radio lobes between 118 MHz and 1.4 GHz reveals significant spatial variation of the spectral index across the lobes, supporting a scenario of multiple outbursts of central activity being responsible for the large-scale morphology. Another nearby radio galaxy, Fornax A, was observed with the complete 128-tile MWA at 154 MHz. The MWA data were used in combination with radio, microwave, X-ray and gamma-ray data to model the spectral energy distribution of Fornax A and investigate, for the first time, the origin of the gamma-ray emission. It was found that the multi-wavelength data are poorly fit by a purely leptonic, inverse-Compton scattering model and that hadronic processes may account for the gamma-ray emission from Fornax A.
Magnetic anisotropy of individual maghemite mesocrystals
Creators: name: Gross, B.
name: Philipp, S.
name: Josten, E.
name: Leliaert, J.
name: Wetterskog, E.
name: Bergström, L.
name: Poggio, M.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Interest in creating magnetic metamaterials has led to methods for growing superstructures of magnetic nanoparticles. Mesoscopic crystals of maghemite ($γ\text{-Fe}_2\text{O}_3$) nanoparticles can be arranged into highly ordered body-centered tetragonal lattices of up to a few micrometers. Although measurements on disordered ensembles have been carried out, determining the magnetic properties of individual mesoscopic crystals is challenging due to their small total magnetic moment. Here, we overcome these challenges by utilizing sensitive dynamic cantilever magnetometry to study individual micrometer-sized $γ\text{-Fe}_2\text{O}_3$ mesocrystals. These measurements reveal an unambiguous cubic anisotropy, resulting from the crystalline anisotropy of the constituent maghemite nanoparticles and their alignment within the mesoscopic lattice. The signatures of anisotropy and its orgins come to light because we combine the self-assembly of highly ordered mesocrystals with the ability to resolve their individual magnetism. This combination is promising for future studies of the magnetic anisotropy of other nanoparticles, which are too small to investigate individually.
description: 13 pages, 12 figures
MacDowell-Mansouri gravity and Cartan geometry
Creators: name: Wise, Derek K.
Publisher: name: arXiv
Year: 2006
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: Differential Geometry (math.DG)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: The geometric content of the MacDowell-Mansouri formulation of general relativity is best understood in terms of Cartan geometry. In particular, Cartan geometry gives clear geometric meaning to the MacDowell-Mansouri trick of combining the Levi-Civita connection and coframe field, or soldering form, into a single physical field. The Cartan perspective allows us to view physical spacetime as tangentially approximated by an arbitrary homogeneous "model spacetime", including not only the flat Minkowski model, as is implicitly used in standard general relativity, but also de Sitter, anti de Sitter, or other models. A "Cartan connection" gives a prescription for parallel transport from one "tangent model spacetime" to another, along any path, giving a natural interpretation of the MacDowell-Mansouri connection as "rolling" the model spacetime along physical spacetime. I explain Cartan geometry, and "Cartan gauge theory", in which the gauge field is replaced by a Cartan connection. In particular, I discuss MacDowell-Mansouri gravity, as well as its more recent reformulation in terms of BF theory, in the context of Cartan geometry.
description: 34 pages, 5 figures. v2: many clarifications, typos corrected
Lexical elicitation: voice quality; Mann 3-118, 315-330
Creators: name: Worahart, Phornphimol
name: Lau-Preechathammarach, Raksit Tyler
Publisher: name: California Language Archive, University of California, Berkeley
Year: 2023
Subjects: subject: sss

description: Elicitation of words differing only in voice quality (modal, breathy) and words from Mann's MSEA Swadesh list 3-118, 315-330. Other voices included. Consultant is a 25-year-old female.
Generalized quaternionic free rotational Dirac equation and spinor solutions in the electromagnetic field
Creators: name: Bhatt, Shikha
name: Chanyal, B. C.
Publisher: name: arXiv
Year: 2022
Subjects: subject: General Physics (physics.gen-ph)
subject: FOS: Physical sciences

description: Starting with the quaternionic Minkowski space-time and its four-vector representation, a rotational analogue of the quaternionic Dirac equation in the electromagnetic field is developed, which includes not only the energy solutions but also the angular momentum solutions for rotating Dirac fermions. The striking feature of the quaternionic approach is that it depicts a unified representation of energy-momentum in a single framework as the space-time. Furthermore, we establish the generalized Schrodinger-Pauli-like equation associated with generalized electric and magnetic dipole energies that corresponding to their dipole moments. As such, the present analysis deals with the invariant behavior of the extended quaternionic rotational Dirac equation under Lorentz, gauge, duality, and CPT invariance.
description: 21 pages, 3 Tables; Int. J. Geom. Methods Mod. Phys. (Accepted) 2022
Dynamic polarization and plasmons in kekulé-patterned graphene: Signatures of the broken valley degeneracy
Creators: name: Herrera, Saúl A.
name: Naumis, Gerardo G.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: The dynamic polarization for kekulé-patterned graphene is studied within the Random Phase Approximation (RPA). It is shown how the breaking of the valley degeneracy by the lattice modulation is manifested through the dielectric spectrum, the plasmonic dispersion, the static screening and the optical conductivity. The valley-dependent splitting of the Fermi velocities due to the kekulé distortion leads to a similar splitting in the dielectric spectrum of graphene, introducing new characteristic frequencies, which are given in terms of the valley-coupling amplitude. The valley coupling also splits the plasmonic dispersion, introducing a second branch in the Landau damping region. Finally, the signatures of the broken valley degeneracy in the optical conductivity are studied. The characteristic step-like spectrum of graphene is split into two half steps due to the onset of absorption in each valley occurring at different characteristic frequencies. Also, it was found an absorption phenomenon where a resonance peak related to intervalley transport emerges at a "beat frequency", determined by the difference between the characteristic frequencies of each valley. Some of these mechanisms are expected to be present in other space-modulated 2D materials and suggest how optical or electrical response measurements can be suitable to detect spatial modulation.
Diaspora activists and military humanitarian intervention
Creators: name: Estrada Harris, Gilberto
Publisher: name: The Australian National University
Year: 2014
Subjects: subject: Humanitarian intervention Political aspects United States
subject: Humanitarian intervention International Cooperation
subject: Transnationalism History 20th century
subject: Political activists
subject: Protest movements United States

description: Research investigating the role of diasporas in conflict has mostly portrayed diasporas as peace wreckers and long-distance nationalists. While there is now increasing recognition of diasporas' positive contributions to their homelands during and after conflict, so far little attention has been paid to the role diaspora groups may play in pushing decisions by their host states to participate in military humanitarian intervention 'back home' in their troubled societies. In this thesis I investigate the active mobilisation of different diaspora groups in the United States during the 1990s and explore the ways in which these mobilisations played into US decisions to intervene. Examining diaspora transnational activism, I argue, can lead to a deeper understanding of how a host state reaches decisions about its interests and moral duties to strangers when facing hard choices about humanitarian intervention. The research I present centres on the values, discourses and processes that help to make military humanitarian interventions possible. I do not seek to analyse the many factors influencing states' decisions to use force for humanitarian purposes, but rather, to investigate how the motivations behind humanitarian action or inaction are created in the first place, and how understandings of sovereignty, self-determination and (non)intervention in the context of humanitarianism can change. I ground my study in a comparative, interpretive analysis of politically active Haitian and Kosovar diaspora members and organisations in the United States in the lead up to Haiti's 1994 and Kosovo's 1999 humanitarian interventions, and of politically active Colombian diaspora members and organisations mobilising for unsuccessful humanitarian intervention in their home conflict. As a result, the thesis as a whole illustrates an important transnational actor-factor that so far has received scant academic attention: diasporas' efforts to educate US decision makers, cultivate an interest in intervening, and help 'rescue' people in danger 'back home'. By analysing diaspora transnational politics in humanitarian intervention, this thesis offers us a lens through which to look at the changing confluence between the state and the individual as a site of identity and of normative and political contestation, with potential humanitarian repercussions.
กระบวนการพัฒนาชุมชนสู่วิถีเศรษฐกิจพอเพียง : กรณีศึกษาบ้านนาเวียง อำเภอเกาะคา จังหวัดลำปาง
Creators: name: จิราณีย์ พันมูล
Publisher: name: มหาวิทยาลัยราชภัฏเชียงราย
Year: 2555

description: 1, 6, วารสารการวิจัยกาสะลองคำ มหาวิทยาลัยราชภัฏเชียงราย
Investigating Neutron Polarizabilities through Compton Scattering on $^3$He
Creators: name: Choudhury, Deepshikha
name: Nogga, Andreas
name: Phillips, Daniel R.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: We examine manifestations of neutron electromagnetic polarizabilities in coherent Compton scattering from the Helium-3 nucleus. We calculate $γ^3$He elastic scattering observables using chiral perturbation theory to next-to-leading order (${\mathcal O}(e^2 Q)$). We find that the unpolarized differential cross section can be used to measure neutron electric and magnetic polarizabilities, while two double-polarization observables are sensitive to different linear combinations of the four neutron spin polarizabilities. [Note added in 2018] An erratum for this paper has been posted as arXiv:1804.01206. Overall conclusions are unchanged, but quantitative results are affected appreciably.
description: 4 pages, 4 figures; version published in Phys. Rev. Lett
Simulating surface height and terminus position for marine outlet glaciers using a level set method with data assimilation
Creators: name: Hossain, M. Alamgir
name: Pimentel, Sam
name: Stockie, John M.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Atmospheric and Oceanic Physics (physics.ao-ph)
subject: Machine Learning (cs.LG)
subject: Computational Physics (physics.comp-ph)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences
subject: 35M10, 65M06, 76D07, 86A40

description: We implement a data assimilation framework for integrating ice surface and terminus position observations into a numerical ice-flow model. The model uses the well-known shallow shelf approximation (SSA) coupled to a level set method to capture ice motion and changes in the glacier geometry. The level set method explicitly tracks the evolving ice-atmosphere and ice-ocean boundaries for a marine outlet glacier. We use an Ensemble Transform Kalman Filter to assimilate observations of ice surface elevation and lateral ice extent by updating the level set function that describes the ice interface. Numerical experiments on an idealized marine-terminating glacier demonstrate the effectiveness of our data assimilation approach for tracking seasonal and multi-year glacier advance and retreat cycles. The model is also applied to simulate Helheim Glacier, a major tidewater-terminating glacier of the Greenland Ice Sheet that has experienced a recent history of rapid retreat. By assimilating observations from remotely-sensed surface elevation profiles we are able to more accurately track the migrating glacier terminus and glacier surface changes. These results support the use of data assimilation methodologies for obtaining more accurate predictions of short-term ice sheet dynamics.
description: 30 pages, 22 figures
title: Analysis of the China Strategy for an Austrian Industrial Automation Company
Creators: name: Li, Renhui
Publisher: name: TU Wien
Year: 2021
Subjects: subject: marketing strategy
subject: china
subject: industrial automation

description: This thesis aims to analyse the existing China strategy for an Austrian industrial automation company, particularly in the light of the confronted challenges. To this end, the company profile and product portfolio have been studied. Furthermore, the China’s macro environment inconsideration of the main challenges has been analysed. In terms of microenvironment, the assessment has been conducted with a particular focus on the market segment injection moulding machine and industrial robotics. Finally, the China strategy has been deviated and evaluations as well as recommendations have been provided.The study has been carried out based on both theoretical and empirical research. Apart from that, an online survey and a semi-structured expert interview have been conducted to obtain aninsight into the main challenges as well as the competitive forces for an Austrian company onthe Chinese automation market. The existing China strategy has been explored and deviatedfrom the expert view. This thesis can be interest ing for the Austrian industry automation company to explore its China strategy in the next years.
Benchmarking Online Sequence-to-Sequence and Character-based Handwriting Recognition from IMU-Enhanced Pens
Creators: name: Ott, Felix
name: Rügamer, David
name: Heublein, Lucas
name: Hamann, Tim
name: Barth, Jens
name: Bischl, Bernd
name: Mutschler, Christopher
Publisher: name: arXiv
Year: 2022
Subjects: subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences
subject: I.5.4
subject: 68T30, 68T10

description: Purpose. Handwriting is one of the most frequently occurring patterns in everyday life and with it come challenging applications such as handwriting recognition (HWR), writer identification, and signature verification. In contrast to offline HWR that only uses spatial information (i.e., images), online HWR (OnHWR) uses richer spatio-temporal information (i.e., trajectory data or inertial data). While there exist many offline HWR datasets, there is only little data available for the development of OnHWR methods on paper as it requires hardware-integrated pens. Methods. This paper presents data and benchmark models for real-time sequence-to-sequence (seq2seq) learning and single character-based recognition. Our data is recorded by a sensor-enhanced ballpoint pen, yielding sensor data streams from triaxial accelerometers, a gyroscope, a magnetometer and a force sensor at 100 Hz. We propose a variety of datasets including equations and words for both the writer-dependent and writer-independent tasks. Our datasets allow a comparison between classical OnHWR on tablets and on paper with sensor-enhanced pens. We provide an evaluation benchmark for seq2seq and single character-based HWR using recurrent and temporal convolutional networks and Transformers combined with a connectionist temporal classification (CTC) loss and cross-entropy (CE) losses. Results. Our convolutional network combined with BiLSTMs outperforms Transformer-based architectures, is on par with InceptionTime for sequence-based classification tasks, and yields better results compared to 28 state-of-the-art techniques. Time-series augmentation methods improve the sequence-based task, and we show that CE variants can improve the single classification task.
description: Accepted for International Journal on Document Analysis and Recognition (IJDAR)
ภาวะผู้นำของนักบัญชี ในธุรกิจวิสาหกิจขนาดกลางและขนาดย่อม
Creators: name: ศุภลักษณ์ จิรรัตน์สถิต
Publisher: name: มหาวิทยาลัยราชภัฏเชียงราย
Year: 2555

description: 1, 6, วารสารการวิจัยกาสะลองคำ มหาวิทยาลัยราชภัฏเชียงราย
GALEX and Optical Light Curves of EF Eridanus During a Low State: the Puzzling Source of UV Light
Creators: name: Szkody, Paula
name: Harrison, Thomas E.
name: Plotkin, Richard M.
name: Howell, Steve B.
name: Seibert, Mark
name: Bianchi, Luciana
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Low state optical photometry of EF Eri during an extended low accretion state combined with GALEX near and far UV time-resolved photometry reveals a source of UV flux that is much larger than the underlying 9500K white dwarf, and that is highly modulated on the orbital period. The near UV and optical light curves can be modeled with a 20,000K spot but no spot model can explain both the large amplitude FUV variations and the SED. The limitations of limb darkening, cyclotron and magnetic white dwarf models in explaining the observations are discussed.
description: 10 pages, 4 figures to be published in ApJ Letters
Quaternionic metamonogenic functions in the unit disk
Creators: name: Morais, J.
name: Porter, R. Michael
Publisher: name: arXiv
Year: 2022
Subjects: subject: Complex Variables (math.CV)
subject: FOS: Mathematics
subject: 30G35 (Primary) 42C30, 35J05, 35Q41 (Secondary)

description: We construct a set of quaternionic metamonogenic functions (that is, in $\mbox{Ker}(D+λ)$ for diverse $λ$) in the unit disk, such that every metamonogenic function is approximable in the quaternionic Hilbert module $L^2$ of the disk. The set is orthogonal except for the small subspace of elements of orders zero and one. These functions are used to express time-dependent solutions of the imaginary-time wave equation in the polar coordinate system.
Household wealth accumulation: impact of tenure choice and home equity loans
Creators: name: Thang, Doreen Chze-Lin
Publisher: name: University of British Columbia
Year: 2009

description: The existing literature on household wealth accumulation has hitherto recognized the lifecycle effects, household socio-economic characteristics, bequest motives, and intergenerational transfers as important factors affecting household net wealth. The two empirical essays in this thesis expand the literature by emphasizing the likely roles that a household's tenure choice and home equity borrowing decisions have in its wealth accumulation process. The first essay, entitled "Homeownership and Household Wealth Accumulation", tests whether homeownership has placed the owner household on a more favorable wealth accumulation path, based on past observations that the values of owner-occupied housing have grown at a real rate greater than those of financial or other tangible assets. The premise is that, while the tenure choice decision is affected by a household's net wealth, the housing tenure chosen could place a household on different wealth accumulation paths over its life-cycle. Controlling for selection bias arising from tenure status, the results indicate that typical homeowners and renters have distinct wealth accumulation processes. While homeownership improves the wealth position of homeowners, the renter households are, however, better off in their existing tenure than otherwise. It appears that households self-select themselves into the appropriate tenure that optimizes their wealth accumulation paths. The second essay on "Household Consumption/Investment Behavior and Home Equity Loans" investigates which behavioral model underpins the homeowners' consumption and investment decisions of home equity loan funds, and how these decisions impact portfolio decisions and wealth accumulation. It concludes that the 'life-cycle model' and the 'precautionary savings model' prevail over the 'bequest motive model' in motivating the household consumption/investment decisions of home equity loans. Home equity loans alter the illiquid nature of housing investment through convenient tapping of housing equity, and reduce household preference to hold liquid assets to meet precautionary needs. Their presence encourages loan users to hold smaller shares of liquid cash and financial assets in total assets, and to diversify from housing asset to business, real estate and illiquid nonhousing assets. They generally reduce homeowners' net wealth, reflecting a tendency for borrowed funds to be consumed or invested in loss-incurring assets.
Robust Estimation of Covariance Matrices: Adversarial Contamination and Beyond
Creators: name: Minsker, Stanislav
name: Wang, Lang
Publisher: name: arXiv
Year: 2022
Subjects: subject: Statistics Theory (math.ST)
subject: FOS: Mathematics
subject: 62G35 (primary)

description: We consider the problem of estimating the covariance structure of a random vector $Y\in \mathbb R^d$ from a sample $Y_1,\ldots,Y_n$. We are interested in the situation when $d$ is large compared to $n$ but the covariance matrix $Σ$ of interest has (exactly or approximately) low rank. We assume that the given sample is (a) $ε$-adversarially corrupted, meaning that $ε$ fraction of the observations could have been replaced by arbitrary vectors, or that (b) the sample is i.i.d. but the underlying distribution is heavy-tailed, meaning that the norm of $Y$ possesses only finite fourth moments. We propose an estimator that is adaptive to the potential low-rank structure of the covariance matrix as well as to the proportion of contaminated data, and admits tight deviation guarantees despite rather weak assumptions on the underlying distribution. Finally, we discuss the algorithms that allow to approximate the proposed estimator in a numerically efficient way.
การศึกษาความต้องการศึกษาต่อด้านสาธารณสุขของบุคลากรในสังกัดองค์กรปกครองส่วนท้องถิ่น ในภาคตะวันออกเฉียงเหนือ ประเทศไทย
Creators: name: กฤติยา พลางวัน
Publisher: name: มหาวิทยาลัยราชภัฏเชียงราย
Year: 2555

description: 1, 6, วารสารการวิจัยกาสะลองคำ มหาวิทยาลัยราชภัฏเชียงราย
Reduced-quaternion inframonogenic functions on the ball
Creators: name: Álvarez, C.
name: Morais, J.
name: Porter, R. Michael
Publisher: name: arXiv
Year: 2022
Subjects: subject: Complex Variables (math.CV)
subject: FOS: Mathematics
subject: Primary 30G35, Secondary 31B30, 33D45, 35G05, 42C30

description: A function $f$ from a domain in $\mathbb{R}^3$ to the quaternions is said to be inframonogenic if $\overline{\partial}\, f\overline{\partial} =0$, where $\overline{\partial} = \partial/\partial x_0+ (\partial/\partial x_1)e_1+(\partial/\partial x_2) e_2$. All inframonogenic functions are biharmonic. In the context of functions $f=f_0+f_1e_1+f_2e_2$ taking values in the reduced quaternions, we show that the homogeneous polynomials of degree $n$ form a subspace of dimension $6n+3$. We use them to construct an explicit, computable orthogonal basis for the Hilbert space of square-integrable inframonogenic functions defined in the ball in $\mathbb{R}^3$.
Human serum albumin at the air-water interface and its interaction with nanoparticles
Creators: name: Ang, Joo Chuan
Publisher: name: The Australian National University
Year: 2014

description: The adsorption mechanism and structure of human serum albumin (fatted and defatted variants) at the air-water interface was investigated using a combination of complementary x-ray and neutron reflectometry. The studies showed that the presence of fatty acid alters the surface activity of the protein. From x-ray and neutron reflectivity measurements, human serum albumin (regardless of the presence or absence of fatty acid) showed an adsorbed structure that is inconsistent with its native solution state. Studies with denaturants found that the air-water interface has a denaturing effect on the tertiary structure of the protein, equivalent to a 1 M guanidinium chloride solution. The interaction of human serum albumin with negatively charged silica nanoparticles were shown to be highly electrostatic in nature and the strength of their interaction can be controlled by the solution pH. Contrast variation in neutron reflectivity was applied to extract compositional information about the binding ratios of serum albumin to silica nanoparticles under different protein concentrations.
Absolutely continuous edge spectrum of topological insulators with an odd time-reversal symmetry
Creators: name: Bols, Alex
name: Cedzich, Christopher
Publisher: name: arXiv
Year: 2022
Subjects: subject: Mathematical Physics (math-ph)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We show that non-trivial two-dimensional topological insulators protected by an odd time-reversal symmetry have absolutely continuous edge spectrum. The proof employs a time-reversal symmetric version of the Wold decomposition that singles out ballistic edge modes of the topological insulator.
description: 10 pages
Lagrangian formulation for an extended cosmological equation-of-state
Creators: name: Panotopoulos, Grigoris
name: Lopes, Ilidio
name: Rincon, Angel
Publisher: name: arXiv
Year: 2020
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We show that the extended cosmological equation-of-state developed starting from a Chaplygin equation-of-state, recently applied to stellar modeling, is a viable dark energy model consistent with standard scalar potentials. Moreover we find a Lagrangian formulation based on a canonical scalar field with the appropriate self-interaction potential. Finally, we fit the scalar potential obtained numerically with concrete functions well studied in the literature. Our results may be of interest to model builders and particle physicists.
description: 6 pages, 3 figures
Embedding cyclic information-theoretic structures in acyclic spacetimes: no-go results for indefinite causality
Creators: name: Vilasini, V.
name: Renner, Renato
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: The notions of causality adopted within the quantum information and spacetime physics communities are distinct. Although both notions play a role in physical experiments, their general interplay is little understood in theory. We develop a theoretical framework that connects the two causality notions, while also clearly distinguishing them. The framework describes a composition of quantum operations through feedback loops, and the embedding of the resulting, possibly cyclic information-theoretic structure in an acyclic spacetime structure. Relativistic causality (which forbids superluminal communication) follows as a graph-theoretic compatibility condition between the two structures. Formulating indefinite causal order (ICO) processes in our framework, we shed light on the links between indefinite and cyclic causality, and on questions regarding their physicality. In particular, there are several experiments that claim to implement ICO processes in Minkowski spacetime, presenting an apparent paradox: how can an indefinite information-theoretic causal structure be consistent with a definite spacetime causal structure? We address this through no-go theorems, showing that as a consequence of relativistic causality, (a) realisations of ICO processes necessarily involve the non-localisation of systems in spacetime and (b) will nevertheless admit an explanation in terms of a definite and acyclic causal order process, at a fine-grained level. This fully resolves the apparent paradox and bears implications for the physical interpretation of ICO experiments, and is achieved by introducing the concept of fine-graining that allows causal structures to be analysed at different levels of detail. Our work also sheds light on the limits of quantum information processing in spacetime and on the operational meaning of indefinite causality, within and beyond the context of a fixed spacetime.
description: 37+30 pages, 17 figures. v4 is closest to published version. An extra result (Theorem 5.8) included in v2 but not in v1 was found to be partly incorrect, it has been removed and does not impact the main results/conclusions. v4 also includes significant improvements to the framework since v1, in terms of clarity and generality, as well as an additional result about the link to causal boxes
Euler-Rodrigues and Cayley formulas for rotation of elasticity tensors
Creators: name: Norris, Andrew N.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: It is fairly well known that rotation in three dimensions can be expressed as a quadratic in a skew symmetric matrix via the Euler-Rodrigues formula. A generalized Euler-Rodrigues polynomial of degree 2n in a skew symmetric generating matrix is derived for the rotation matrix of tensors of order $n$. The Euler-Rodrigues formula for rigid body rotation is recovered by n=1. A Cayley form of the n-th order rotation tensor is also derived. The representations simplify if there exists some underlying symmetry, as is the case for elasticity tensors such as strain and the fourth order tensor of elastic moduli. A new formula is presented for the transformation of elastic moduli under rotation: as a 21-vector with a rotation matrix given by a polynomial of degree 8. Explicit spectral representations are constructed from three vectors: the axis of rotation and two orthogonal bivectors. The tensor rotation formulae are related to Cartan decomposition of elastic moduli and projection onto hexagonal symmetry.
description: 26 pages
Coherent manipulation of an Andreev spin qubit
Creators: name: Hays, M.
name: Fatemi, V.
name: Bouman, D.
name: Cerrillo, J.
name: Diamond, S.
name: Serniak, K.
name: Connolly, T.
name: Krogstrup, P.
name: Nygård, J.
name: Yeyati, A. Levy
name: Geresdi, A.
name: Devoret, M. H.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Superconductivity (cond-mat.supr-con)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Two promising architectures for solid-state quantum information processing are electron spins in semiconductor quantum dots and the collective electromagnetic modes of superconducting circuits. In some aspects, these two platforms are dual to one another: superconducting qubits are more easily coupled but are relatively large among quantum devices $(\sim\mathrm{mm})$, while electrostatically-confined electron spins are spatially compact ($\sim \mathrm{μm}$) but more complex to link. Here we combine beneficial aspects of both platforms in the Andreev spin qubit: the spin degree of freedom of an electronic quasiparticle trapped in the supercurrent-carrying Andreev levels of a Josephson semiconductor nanowire. We demonstrate coherent spin manipulation by combining single-shot circuit-QED readout and spin-flipping Raman transitions, finding a spin-flip time $T_S = 17~\mathrm{μs}$ and a spin coherence time $T_{2E}=52~\mathrm{ns}$. These results herald a new spin qubit with supercurrent-based circuit-QED integration and further our understanding and control of Andreev levels -- the parent states of Majorana zero modes -- in semiconductor-superconductor heterostructures.
Quality assessment of a landslide inventory map and its
application to land‐use planning. A case study in the
Northern Apennines (Emilia‐Romagna region, Italy)
Creators: name: Baroni, Cristina <1973>
Publisher: name: Alma Mater Studiorum - Università di Bologna
Year: 2015
Subjects: GEO/02 Geologia stratigrafica e sedimentologica

description: Landslide hazard and risk are growing as a consequence of climate change and demographic pressure. Land‐use planning represents a powerful tool to manage this socio‐economic problem and build sustainable and landslide resilient communities. Landslide inventory maps are a cornerstone of land‐use planning and, consequently, their quality assessment represents a burning issue.
This work aimed to define the quality parameters of a landslide inventory and assess its spatial and temporal accuracy with regard to its possible applications to land‐use planning. In this sense, I proceeded according to a two‐steps approach. An overall assessment of the accuracy of data geographic positioning was performed on four case study sites located in the Italian Northern Apennines. The quantification of the overall spatial and temporal accuracy, instead, focused on the Dorgola Valley (Province of Reggio Emilia). The assessment of spatial accuracy involved a comparison between remotely sensed and field survey data, as well as an innovative fuzzylike analysis of a multi‐temporal landslide inventory map. Conversely, long‐ and short‐term landslide temporal persistence was appraised over a period of 60 years with the aid of 18 remotely sensed image sets. These results were eventually compared with the current Territorial Plan for Provincial Coordination (PTCP) of the Province of Reggio Emilia.
The outcome of this work suggested that geomorphologically detected and mapped landslides are a significant approximation of a more complex reality. In order to convey to the end‐users this intrinsic uncertainty, a new form of cartographic representation is needed. In this sense, a fuzzy raster landslide map may be an option. With regard to land‐use planning, landslide inventory maps, if appropriately updated, confirmed to be essential decision‐support tools. This research, however, proved that their spatial and temporal uncertainty discourages any direct use as zoning maps, especially when zoning itself is associated to statutory or advisory regulations.
Efficient Estimation of Material Property Curves and Surfaces via Active Learning
Creators: name: Tian, Yuan
name: Xue, Dezhen
name: Yuan, Ruihao
name: Zhou, Yumei
name: Ding, Xiangdong
name: Sun, Jun
name: Lookman, Turab
Publisher: name: arXiv
Year: 2020
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Computational Physics (physics.comp-ph)
subject: FOS: Physical sciences

description: The relationship between material properties and independent variables such as temperature, external field or time, is usually represented by a curve or surface in a multi-dimensional space. Determining such a curve or surface requires a series of experiments or calculations which are often time and cost consuming. A general strategy uses an appropriate utility function to sample the space to recommend the next optimal experiment or calculation within an active learning loop. However, knowing what the optimal sampling strategy to use to minimize the number of experiments is an outstanding problem. We compare a number of strategies based on directed exploration on several materials problems of varying complexity using a Kriging based model. These include one dimensional curves such as the fatigue life curve for 304L stainless steel and the Liquidus line of the Fe-C phase diagram, surfaces such as the Hartmann 3 function in 3D space and the fitted intermolecular potential for Ar-SH, and a four dimensional data set of experimental measurements for BaTiO3 based ceramics. We also consider the effects of experimental noise on the Hartmann 3 function. We find that directed exploration guided by maximum variance provides better performance overall, converging faster across several data sets. However, for certain problems, the trade-off methods incorporating exploitation can perform at least as well, if not better than maximum variance. Thus, we discuss how the choice of the utility function depends on the distribution of the data, the model performance and uncertainties, additive noise as well as the budget.
description: 15 pages and 15 figures,submitted to Physical Review Materials
Sharp estimates for the first Robin eigenvalue of nonlinear elliptic operators
Creators: name: Della Pietra, Francesco
name: Piscitelli, Gianpaolo
Publisher: name: arXiv
Year: 2022
Subjects: subject: Analysis of PDEs (math.AP)
subject: FOS: Mathematics
subject: 35J25 35P15 47J10 47J30

description: The aim of this paper is to obtain optimal estimates for the first Robin eigenvalue of the anisotropic $p$-Laplace operator, namely: \begin{equation*} λ_1(β,Ω)=\min_{ψ\in W^{1,p}(Ω)\setminus\{0\} } \frac{\displaystyle\int_ΩF(\nabla ψ)^p dx +β\displaystyle\int_{\partialΩ}|ψ|^pF(ν_Ω) d\mathcal H^{N-1} }{\displaystyle\int_Ω|ψ|^p dx}, \end{equation*} where $p\in]1,+\infty[$, $Ω$ is a bounded, mean convex domain in $\mathbb R^{N}$, $ν_Ω$ is its Euclidean outward normal, $β$ is a real number, and $F$ is a sufficiently smooth norm on $\mathbb R^{N}$. The estimates we found are in terms of the first eigenvalue of a one-dimensional nonlinear problem, which depends on $β$ and on geometrical quantities associated to $Ω$. More precisely, we prove a lower bound of $λ_{1}$ in the case $β>0$, and a upper bound in the case $β<0$. As a consequence, we prove, for $β>0$, a lower bound for $λ_{1}(β,Ω)$ in terms of the anisotropic inradius of $Ω$ and, for $β<0$, an upper bound of $λ_{1}(β,Ω)$ in terms of $β$.
description: 24 pages
Secondary Microseisms Characterization and Green’s
Function Extraction at the Larderello-Travale
Geothermal Field (Italy)
Creators: name: Zupo, Maria <1983>
Publisher: name: Alma Mater Studiorum - Università di Bologna
Year: 2015
Subjects: GEO/10 Geofisica della terra solida

description: Over the past ten years, the cross-correlation of long-time series of ambient
seismic noise (ASN) has been widely adopted to extract the surface-wave
part of the Green’s Functions (GF). This stochastic procedure relies on the
assumption that ASN wave-field is diffuse and stationary. At frequencies <1Hz, the ASN is mainly composed by surface-waves, whose origin is attributed
to the sea-wave climate. Consequently, marked directional properties may be
observed, which call for accurate investigation about location and temporal
evolution of the ASN-sources before attempting any GF retrieval. Within
this general context, this thesis is aimed at a thorough investigation about
feasibility and robustness of the noise-based methods toward the imaging
of complex geological structures at the local (∼10-50km) scale. The study
focused on the analysis of an extended (11 months) seismological data set
collected at the Larderello-Travale geothermal field (Italy), an area for which
the underground geological structures are well-constrained thanks to decades
of geothermal exploration.
Focusing on the secondary microseism band (SM;f>0.1Hz), I first
investigate the spectral features and the kinematic properties of the noise
wavefield using beamforming analysis, highlighting a marked variability with
time and frequency. For the 0.1-0.3Hz frequency band and during Spring-
Summer-time, the SMs waves propagate with high apparent velocities and
from well-defined directions, likely associated with ocean-storms in the south-
ern hemisphere. Conversely, at frequencies >0.3Hz the distribution of back-
azimuths is more scattered, thus indicating that this frequency-band is the
most appropriate for the application of stochastic techniques. For this latter
frequency interval, I tested two correlation-based methods, acting in the time
(NCF) and frequency (modified-SPAC) domains, respectively yielding esti-
mates of the group- and phase-velocity dispersions. Velocity data provided
by the two methods are markedly discordant; comparison with independent
geological and geophysical constraints suggests that NCF results are more
robust and reliable.
In memoriam of Heidi Günthart (1919 – 2023)
Creators: name: Mühlethaler, Roland
name: Hoch, Hannelore
Publisher: name: Cicadina
Year: 2023
Subjects: subject: 000

description: Nachruf auf Heidi Günthart (1919 - 2023)
description: In memoriam of Heidi Günthart (1919 – 2023)
Probe method and a Carleman function
Creators: name: Ikehata, Masaru
Publisher: name: arXiv
Year: 2007
Subjects: subject: Analysis of PDEs (math.AP)
subject: Mathematical Physics (math-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences
subject: 35R30, 35R25, 35J05, 33E12, 35C05

description: A Carleman function is a special fundamental solution with a large parameter for the Laplace operator and gives a formula to calculate the value of the solution of the Cauchy problem in a domain for the Laplace equation. The probe method applied to an inverse boundary value problem for the Laplace equation in a bounded domain is based on the existence of a special sequence of harmonic functions which is called a {\it needle sequence}. The needle sequence blows up on a special curve which connects a given point inside the domain with a point on the boundary of the domain and is convergent locally outside the curve. The sequence yields a reconstruction formula of unknown discontinuity, such as cavity, inclusion in a given medium from the Dirichlet-to-Neumann map. In this paper, an explicit needle sequence in {\it three dimensions} is given in a closed form. It is an application of a Carleman function introduced by Yarmukhamedov. Furthermore, an explicit needle sequence in the probe method applied to the reduction of inverse obstacle scattering problems with an {\it arbitrary} fixed wave number to inverse boundary value problems for the Helmholtz equation is also given.
description: 2 figures, final version