cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Structure of Fe3Si/Al/Fe3Si thin film stacks on GaAs(001)
Creators: name: Jenichen, Bernd
name: Jahn, Uwe
name: Nikulin, Andrei
name: Herfort, Jens
name: Kirmse, Holm
Publisher: name: arXiv
Year: 2015
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Fe3Si/Al/Fe3Si/GaAs(001) structures were deposited by molecular-beam epitaxy and characterized by transmission and scanning electron microscopy, and x-ray diffraction. The first Fe3Si film on GaAs(001) is growing epitaxially as (001) oriented single crystal. The subsequent Al film grows almost 111 oriented in a fibre texture although the underlying Fe3Si is exactly (001) oriented. The growth in this orientation is triggered by a thin transition region which is formed at the Fe3Si/Al interface. In the end after the growth of the second Fe3Si layer on top of the Al the final properties of the whole stack depend on the substrate temperature T_S during deposition of the last film. The upper Fe3Si films are mainly 110 oriented although they are poly-crystalline. At lower T_S, around room temperature, all the films retain their original structural properties.
description: Microscopy of Semiconducting Materials 2015
Effective Field Theory of Dark Matter from membrane inflationary paradigm
Creators: name: Choudhury, Sayantan
name: Dasgupta, Arnab
Publisher: name: arXiv
Year: 2015
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: In this article, we have studied the cosmological and particle physics constraints on dark matter relic abundance from effective field theory of inflation using tensor-to-scalar ratio ($r$), in case of Randall-Sundrum single membrane (RSII) paradigm. Using semi-analytical approach we establish a direct connection between the dark matter relic abundance ($Ω_{DM}h^2$) and primordial gravity waves ($r$), which establishes a precise connection between inflation and generation of dark matter within the framework of effective field theory in RSII membrane. Further assuming the UV completeness of the effective field theory perfectly holds good in the prescribed framework, we have explicitly shown that the membrane tension, $σ$, bulk mass scale $M_5$, and cosmological constant $\tildeΛ_{5}$, in RSII membrane plays the most significant role to establish the connection between dark matter and inflation, using which we have studied the features of various mediator mass scale suppressed effective field theory "relevant operators" induced from the localized $s$, $t$ and $u$ channel interactions. Taking a completely model independent approach, we have studied an exhaustive list of tree-level Feynman diagrams for dark matter annihilation within the prescribed setup and to check the consistency of the obtained results, further we apply the constraints as obtained from recently observed Planck 2015 data and Planck+BICEP2+Keck Array joint datasets. Using all of these derived results we have shown that to satisfy the bound on, $Ω_{DM}h^2=0.1187\pm 0.0017$, as from Planck 2015 data, it is possible to put further stringent constraint on $r$ within, $0.01\leq r\leq 0.12$, for thermally averaged annihilation cross-section of dark matter, $\langle σv\rangle\approx {\cal O}(10^{-28}-10^{-27}){\rm cm^3 /s}$, which are very useful to constrain various membrane inflationary models.
description: 67 pages, 27 figures, 1 table, Final version, Accepted for publication in Physics of the Dark Universe
The Role of Automated Categorisation in e-Government Information Retrieval
Creators: name: Svarre, Tanja
name: Lykke, Marianne
Publisher: name: Zenodo
Year: 2013
Subjects: subject: automated categorisation
subject: e-government information
subject: https://iskouk.org/subjects/PRUIHEDJ

description: High-precision search results are essential for helping e-government employees complete work-based tasks. Prior studies have shown that existing features of e-government systems need improvement in terms of search facilities, navigation, and metadata adoption. This paper investigates how automated categorization can enhance information organization and retrieval and presents the results of a controlled evaluation that compared automated categorization and free text indexing of the government intranet used by Danish tax authorities. Thirty-two individuals participated in the evaluation, conducting simulated searches and genuine search tasks. Searching behaviour and search outcome was documented by search logs, relevance assessments, and post search interviews. The evaluation demonstrates a high potential for automated categorization in a government context. Overall, the categorized organization generated more reformulations and less query success. Session success was found to be fairly even between the two systems. Qualitative data revealed that categorized overviews of the search results were useful if the participating employee did not possess extensive knowledge of the task at hand. When task knowledge was present, categorization was used to support the assumptions of a correct search. On the other hand, however, test participants avoided using automated categorization if high-precision documents were among the top results or if few documents were retrieved. The findings emphasize the importance of simultaneously providing different search options for e-government IR systems and reveal that automated categorization is a valuable candidate for improving search facilities within this domain.
Deformable MR Prostate Segmentation via Deep Feature Learning and Sparse Patch Matching
Creators: name: Guo, Yanrong
name: Gao, Yaozong
name: Shen, Dinggang
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2016

description: Automatic and reliable segmentation of the prostate is an important but difficult task for various clinical applications such as prostate cancer radiotherapy. The main challenges for accurate MR prostate localization lie in two aspects: (1) inhomogeneous and inconsistent appearance around prostate boundary, and (2) the large shape variation across different patients. To tackle these two problems, we propose a new deformable MR prostate segmentation method by unifying deep feature learning with the sparse patch matching. First, instead of directly using handcrafted features, we propose to learn the latent feature representation from prostate MR images by the stacked sparse auto-encoder (SSAE). Since the deep learning algorithm learns the feature hierarchy from the data, the learned features are often more concise and effective than the handcrafted features in describing the underlying data. To improve the discriminability of learned features, we further refine the feature representation in a supervised fashion. Second, based on the learned features, a sparse patch matching method is proposed to infer a prostate likelihood map by transferring the prostate labels from multiple atlases to the new prostate MR image. Finally, a deformable segmentation is used to integrate a sparse shape model with the prostate likelihood map for achieving the final segmentation. The proposed method has been extensively evaluated on the dataset that contains 66 T2-wighted prostate MR images. Experimental results show that the deep-learned features are more effective than the handcrafted features in guiding MR prostate segmentation. Moreover, our method shows superior performance than other state-of-the-art segmentation methods.
Detecting Anatomical Landmarks for Fast Alzheimer’s Disease Diagnosis
Creators: name: Shen, Dinggang
name: Zhang, Jun
name: Gao, Yue
name: Munsell, Brent C.
name: Gao, Yaozong
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2016

description: Structural magnetic resonance imaging (MRI) is a very popular and effective technique used to diagnose Alzheimer’s disease (AD). The success of computer-aided diagnosis methods using structural MRI data is largely dependent on the two time-consuming steps: 1) nonlinear registration across subjects, and 2) brain tissue segmentation. To overcome this limitation, we propose a landmark-based feature extraction method that does not require nonlinear registration and tissue segmentation. In the training stage, in order to distinguish AD subjects from healthy controls (HCs), group comparisons, based on local morphological features, are first performed to identify brain regions that have significant group differences. In general, the centers of the identified regions become landmark locations (or AD landmarks for short) capable of differentiating AD subjects from HCs. In the testing stage, using the learned AD landmarks, the corresponding landmarks are detected in a testing image using an efficient technique based on a shape-constrained regression-forest algorithm. To improve detection accuracy, an additional set of salient and consistent landmarks are also identified to guide the AD landmark detection. Based on the identified AD landmarks, morphological features are extracted to train a support vector machine (SVM) classifier that is capable of predicting the AD condition. In the experiments, our method is evaluated on landmark detection and AD classification sequentially. Specifically, the landmark detection error (manually annotated versus automatically detected) of the proposed landmark detector is 2.41mm, and our landmark-based AD classification accuracy is 83.7%. Lastly, the AD classification performance of our method is comparable to, or even better than, that achieved by existing region-based and voxel-based methods, while the proposed method is approximately 50 times faster.
The chiral phase transition for lattice QCD with 2 colour-sextet quarks
Creators: name: Kogut, J. B.
name: Sinclair, D. K.
Publisher: name: arXiv
Year: 2015
Subjects: subject: High Energy Physics - Lattice (hep-lat)
subject: FOS: Physical sciences

description: QCD with 2 flavours of massless colour-sextet quarks is studied as a possible walking-Technicolor candidate. We simulate the lattice version of this model at finite temperatures near to the chiral-symmetry restoration transition, to determine whether it is indeed a walking theory (QCD-like with a running coupling which evolves slowly over an appreciable range of length scales) or if it has an infrared fixed point, making it a conformal field theory. The lattice spacing at this transition is decreased towards zero by increasing the number $N_t$ of lattice sites in the temporal direction. Our simulations are performed at $N_t=4,6,8,12$, on lattices with spatial extent much larger than the temporal extent. A range of small fermion masses is chosen to make predictions for the chiral (zero mass) limit. We find that the bare lattice coupling does decrease as the lattice spacing is decreased. However, it decreases more slowly than would be predicted by asymptotic freedom. We discuss whether this means that the coupling is approaching a finite value as lattice $N_t$ is increased -- the conformal option, or if the apparent disagreement with the scaling predicted by asymptotic freedom is because the lattice coupling is a poor expansion parameter, and the theory walks. Currently, evidence favours QCD with 2 colour-sextet quarks being a conformal field theory. Other potential sources of disagreement with the walking hypothesis are also discussed. We also report an estimate of the position of the deconfinement transition for $N_t=12$, needed for choosing parameters for zero-temperature simulations.
description: 27 pages, 11 postscript figures. Added several references. Extensive modification to conclusions. Added paragraph to section 4
The Physics of Stratum Corneum Lipid Membranes
Creators: name: Das, Chinmay
name: Olmsted, Peter D.
Publisher: name: arXiv
Year: 2015
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: Biological Physics (physics.bio-ph)
subject: Chemical Physics (physics.chem-ph)
subject: Tissues and Organs (q-bio.TO)
subject: FOS: Physical sciences
subject: FOS: Biological sciences

description: The Stratum Corneum (SC), the outermost layer of skin, comprises rigid corneocytes (keratin filled dead cells) in a specialized lipid matrix. The continuous lipid matrix provides the main barrier against uncontrolled water loss and invasion of external pathogens. Unlike all other biological lipid membranes (like intracellular organelles and plasma membranes), molecules in SC lipid matrix show small hydrophilic group and large variability in the length of the alkyl tails and in the numbers and positions of groups that are capable of forming hydrogen bonds. Molecular simulations provide a route for systematically probing the effects of each of these differences separately. In this article we present results from atomistic molecular dynamics of selected lipid bilayers and multilayers to probe the effect of these polydispersities. We address the nature of the tail packing in the gel-like phase, the hydrogen bond network among head groups, the bending moduli expected for leaflets comprising SC lipids, and the conformation of very long ceramide lipids (EOS) in multibilayer lipid assemblies.
description: 13 pages, from the Royal Society Discussion Meeting "Soft Interfacial Materials: from fundamentals to formulation", 12-13 October 2015, London
Hybrid Metal-Graphene Plasmons for Tunable Terahertz Technology
Creators: name: Jadidi, Mohammad M.
name: Sushkov, Andrei B.
name: Myers-Ward, Rachael L.
name: Boyd, Anthony K.
name: Daniels, Kevin M.
name: Gaskill, D. Kurt
name: Fuhrer, Michael S.
name: Drew, H. Dennis
name: Murphy, Thomas E.
Publisher: name: arXiv
Year: 2015
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Among its many outstanding properties, graphene supports terahertz surface plasma waves -- sub-wavelength charge density oscillations connected with electromagnetic fields that are tightly localized near the surface[1,2]. When these waves are confined to finite-sized graphene, plasmon resonances emerge that are characterized by alternating charge accumulation at the opposing edges of the graphene. The resonant frequency of such a structure depends on both the size and the surface charge density, and can be electrically tuned throughout the terahertz range by applying a gate voltage[3,4]. The promise of tunable graphene THz plasmonics has yet to be fulfilled, however, because most proposed optoelectronic devices including detectors, filters, and modulators[5-10] desire near total modulation of the absorption or transmission, and require electrical contacts to the graphene -- constraints that are difficult to meet using existing plasmonic structures. We report here a new class of plasmon resonance that occurs in a hybrid graphene-metal structure. The sub-wavelength metal contacts form a capacitive grid for accumulating charge, while the narrow interleaved graphene channels, to first order, serves as a tunable inductive medium, thereby forming a structure that is resonantly-matched to an incident terahertz wave. We experimentally demonstrate resonant absorption near the theoretical maximum in readily-available, large-area graphene, ideal for THz detectors and tunable absorbers. We further predict that the use of high mobility graphene will allow resonant THz transmission near 100%, realizing a tunable THz filter or modulator. The structure is strongly coupled to incident THz radiation, and solves a fundamental problem of how to incorporate a tunable plasmonic channel into a device with electrical contacts.
It Starts at Home: Infusing Radical Empathy into Graduate Education
Creators: name: Cooke, Nicole Amy
name: Warren, Kellee
name: Brown, Molly
name: Jackson, Athena
Publisher: name: University of Illinois at Chicago
Year: 2023
Subjects: Uncategorized

description: This interview features a conversation between a library and information science educator (Cooke) and three archival and special collections professionals with varying levels of experience in the field (Warren, Brown, and Jackson). Among the goals of this frank conversation is to highlight the lived experiences of practicing archivists and educators and discuss why it is becoming increasingly important to talk about empathy, diversity, equity, and inclusion in greater context. As part of that context, we must discuss the need to continuously infuse these values into graduate education, professional development, research, writing, and peer mentoring. Espousing and implementing an ethics of care is an ongoing and necessary process and commitment—to ourselves, to the information professions, and to our communities.
Transversely holomorphic flows and contact circles on spherical 3-manifolds
Creators: name: Geiges, Hansjörg
name: Gonzalo, Jesús
Publisher: name: arXiv
Year: 2015
Subjects: subject: Differential Geometry (math.DG)
subject: Geometric Topology (math.GT)
subject: Symplectic Geometry (math.SG)
subject: FOS: Mathematics
subject: 53C12, 53D35, 57M50, 57R30, 58D27

description: Motivated by the moduli theory of taut contact circles on spherical 3-manifolds, we relate taut contact circles to transversely holomorphic flows. We give an elementary survey of such 1-dimensional foliations from a topological viewpoint. We describe a complex analogue of the classical Godbillon-Vey invariant, the so-called Bott invariant, and a logarithmic monodromy of closed leaves. The Bott invariant allows us to formulate a generalised Gauß-Bonnet theorem. We compute these invariants for the Poincaré foliations on the 3-sphere and derive rigidity statements, including a uniformisation theorem for orbifolds. These results are then applied to the classification of taut contact circles.
description: 31 pages, 3 figures; v2: changes to the exposition, additional references
The kinetic analysis of fructan biosynthesis in excised leaves of Lolium temulentum L.
Creators: name: Sims, Ian
name: MORGAN, R
name: POLLOCK, CJ
Publisher: name: Open Access Te Herenga Waka-Victoria University of Wellington
Year: 2022
Subjects: Uncategorized

description: Excised leaves of Lolium temulentum L. were fed 1CO. at 99% isotopic abundance in order to study the kinetics of incorporation of photosynthetically fixed carbon into different fructans and to determine the pathways of synthesis between sucrose and high‐molecular‐weight fructan. Following 6 h exposure to CO2 of detached and illuminated leaves, analysis of the accumulation of I‐keatose, 6–kestose and neokestose, and of the pattern of labelling observed in these isomers, suggested that they were each formed directly from sucrose at different rates. Similarly, the data suggested thai the tetrasaccharide isomers were formed directly from their trisaccharide precursors. Changes in the concentration of 13C both in the total water‐soluble component of the leaves and the fructan pool after 20h exposure to 13Co2 suggested that there was a continual turnover of frunctosyl residues. The formation of trisaccharides From sucrose and subsequent frunctosyl transfer to oligo‐ and polysaccharides of progressively higher molecular weight was consistent with a direct precursor product relationship. The stable concenttation of sucrose observed in leaves between 14 h and 48 h after excision indicated that fructan metabolism in L. temulentum may serve to regulate the sucrose content of the tissue. Copyright © 1993, Wiley Blackwell. All rights reserved
Scaling Exponents for Lattice Quantum Gravity in Four Dimensions
Creators: name: Hamber, Herbert W.
Publisher: name: arXiv
Year: 2015
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Lattice (hep-lat)
subject: FOS: Physical sciences

description: In this work nonperturbative aspects of quantum gravity are investigated using the lattice formulation, and some new results are presented for critical exponents, amplitudes and invariant correlation functions. Values for the universal scaling dimensions are compared with other nonperturbative approaches to gravity in four dimensions, and specifically to the conjectured value for the universal critical exponent $ν=1 /3$. It is found that the lattice results are generally consistent with gravitational anti-screening, which would imply a slow increase in the strength of the gravitational coupling with distance, and here detailed estimates for exponents and amplitudes characterizing this slow rise are presented. Furthermore, it is shown that in the lattice approach (as for gauge theories) the quantum theory is highly constrained, and eventually by virtue of scaling depends on a rather small set of physical parameters. Arguments are given in support of the statement that the fundamental reference scale for the growth of the gravitational coupling $G$ with distance is represented by the observed scaled cosmological constant $λ$, which in gravity acts as an effective nonperturbative infrared cutoff. In the vacuum condensate picture a fundamental relationship emerges between the scale characterizing the running of $G$ at large distances, the macroscopic scale for the curvature as described by the observed cosmological constant, and the behavior of invariant gravitational correlation functions at large distances. Overall, the lattice results suggest that the infrared slow growth of $G$ with distance should become observable only on very large distance scales, comparable to $λ$. It is hoped that future high precision satellite experiments will possibly come within reach of this small quantum correction, as suggested by a vacuum condensate picture of quantum gravity.
description: 66 pages, 21 figures
Ising Superconductivity and Majorana Fermions in Transition Metal Dichalcogenides
Creators: name: Zhou, Benjamin T.
name: Yuan, Noah F. Q.
name: Jiang, Hong-Liang
name: Law, K. T.
Publisher: name: arXiv
Year: 2015
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: In monolayer transition metal dichalcogenides (TMDs), electrons in opposite $K$ valleys are subject to opposite effective Zeeman fields, which are referred to as Ising spin-orbit coupling (SOC) fields. The Ising SOC, originated from in-plane mirror symmetry breaking pins the electron spins in out-of-plane directions, and results in the newly discovered Ising superconducting states with strongly enhanced upper critical fields. In this work, we show that the Ising SOC generates equal-spin triplet Cooper pairs with spin polarization in the in-plane directions. Importantly, the spin-triplet Cooper pairs can induce superconducting pairings in a half-metal wire placed on top of the TMD and result in a topological superconductor with Majorana end states. Direct ways to detect equal-spin triplet Cooper pairs and the differences between Ising superconductors and Rashba superconductors are discussed.
description: 5 pages, 3 figures. Comments are welcome
Interaction-enabled topological phases in topological insulator-superconductor heterostructures
Creators: name: Pikulin, D. I.
name: Chiu, Ching-Kai
name: Zhu, Xiaoyu
name: Franz, M.
Publisher: name: arXiv
Year: 2015
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: Topological phases of matter that depend for their existence on interactions are fundamentally interesting and potentially useful as platforms for future quantum computers. Despite the multitude of theoretical proposals the only interaction-enabled topological phase experimentally observed is the fractional quantum Hall liquid. To help identify other systems that can give rise to such phases we present in this work a detailed study of the effect of interactions on Majorana zero modes bound to vortices in a superconducting surface of a 3D topological insulator. This system is of interest because, as was recently pointed out, it can be tuned into the regime of strong interactions. We start with a 0D system suggesting an experimental realization of the interaction-induced $\mathbb{Z}_8$ ground state periodicity previously discussed by Fidkowski and Kitaev. We argue that the periodicity is experimentally observable using a tunnel probe. We then focus on interaction-enabled crystalline topological phases that can be built with the Majoranas in a vortex lattice in higher dimensions. In 1D we identify an interesting exactly solvable model which is related to a previously discussed one that exhibits an interaction-enabled topological phase. We study these models using analytical techniques, exact numerical diagonalization (ED) and density matrix renormalization group (DMRG). Our results confirm the existence of the interaction-enabled topological phase and clarify the nature of the quantum phase transition that leads to it. We finish with a discussion of models in dimensions 2 and 3 that produce similar interaction-enabled topological phases.
description: 14 pages, 8 figures; v2
Estimating CT Image From MRI Data Using Structured Random Forest and Auto-Context Model
Creators: name: Huynh, Tri
name: Shen, Dinggang
name: Gao, Yaozong
name: Wang, Li
name: Lian, Jun
name: Zhang, Pei
name: Kang, Jiayin
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2016

description: Computed tomography (CT) imaging is an essential tool in various clinical diagnoses and radiotherapy treatment planning. Since CT image intensities are directly related to positron emission tomography (PET) attenuation coefficients, they are indispensable for attenuation correction (AC) of the PET images. However, due to the relatively high dose of radiation exposure in CT scan, it is advised to limit the acquisition of CT images. In addition, in the new PET and magnetic resonance (MR) imaging scanner, only MR images are available, which are unfortunately not directly applicable to AC. These issues greatly motivate the development of methods for reliable estimate of CT image from its corresponding MR image of the same subject. In this paper, we propose a learning-based method to tackle this challenging problem. Specifically, we first partition a given MR image into a set of patches. Then, for each patch, we use the structured random forest to directly predict a CT patch as a structured output, where a new ensemble model is also used to ensure the robust prediction. Image features are innovatively crafted to achieve multi-level sensitivity, with spatial information integrated through only rigid-body alignment to help avoiding the error-prone inter-subject deformable registration. Moreover, we use an auto-context model to iteratively refine the prediction. Finally, we combine all of the predicted CT patches to obtain the final prediction for the given MR image. We demonstrate the efficacy of our method on two datasets: human brain and prostate images. Experimental results show that our method can accurately predict CT images in various scenarios, even for the images undergoing large shape variation, and also outperforms two state-of-the-art methods.
Order-Fractal transition in abstract paintings
Creators: name: De la Calleja, E. M.
name: Cervantes, F.
name: De la Calleja, J.
Publisher: name: arXiv
Year: 2015
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Computer and information sciences

description: We report the degree of order of twenty-two Jackson Pollock's paintings using \emph{Hausdorff-Besicovitch fractal dimension}. Through the maximum value of each multi-fractal spectrum, the artworks are classify by the year in which they were painted. It has been reported that Pollock's paintings are fractal and it increased on his latest works. However our results show that fractal dimension of the paintings are on a range of fractal dimension with values close to two. We identify this behavior as a fractal-order transition. Based on the study of disorder-order transition in physical systems, we interpreted the fractal-order transition through its dark paint strokes in Pollocks' paintings, as structured lines following a power law measured by fractal dimension. We obtain self-similarity in some specific Pollock's paintings, that reveal an important dependence on the scale of observation. We also characterize by its fractal spectrum, the called \emph{Teri's Find}. We obtained similar spectrums between \emph{Teri's Find} and \emph{Number 5} from Pollock, suggesting that fractal dimension cannot be completely rejected as a quantitative parameter to authenticate this kind of artworks.
Holographic entanglement entropy in superconductor phase transition with dark matter sector
Creators: name: Peng, Yan
Publisher: name: arXiv
Year: 2015
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: In this paper, we investigate the holographic phase transition with dark matter sector in the AdS black hole background away from the probe limit. We disclose the properties of phases mostly from the holographic topological entanglement entropy of the system. We find the entanglement entropy is a good probe to the critical temperature and the order of the phase transition in the general model. The behaviors of entanglement entropy at large strip size suggest that the area law still holds with dark matter sector. We also conclude that the holographic topological entanglement entropy is useful in detecting the stability of the phase transitions. Furthermore, we derive the complete diagram of the effects of coupled parameters on the critical temperature through the entanglement entropy and analytical methods.
description: 15 pages, 7 figures
The relativistic electron gas: a candidate for nature's left-handed material
Creators: name: de Carvalho, C. A. A.
Publisher: name: arXiv
Year: 2015
Subjects: subject: Quantum Physics (quant-ph)
subject: Other Condensed Matter (cond-mat.other)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: The electric permittivities and magnetic permeabilities for a relativistic electron gas are calculated from quantum electrodynamics at finite temperature and density as functions of temperature, chemical potential, frequency, and wavevector. The polarization and the magnetization depend linearly on both electric and magnetic fields, and are the sum of a zero-temperature and zero-density vacuum part with a temperature- and chemical potential-dependent medium part. Analytic calculations lead to generalized expressions that depend on three scalar functions. In the nonrelativistic limit, results reproduce the Lindhard formula. In the relativistic case, and in the long wavelength limit, we obtain: i) for $ω=0$, generalized susceptibilities that reduce to known nonrelativistic limits; ii) for $ω\neq 0$, Drude-type responses at zero and at high temperatures. The latter implies that one may have both $ε$ and $μ$ simultaneously negative, a behavior characteristic of metamaterials. This unambiguously indicates that the relativistic electron plasma is one of nature's candidates for the realization of a negative index of refraction system. Moreover, Maxwell's equations in the medium yield the dispersion relation and the index of refraction of the electron plasma. Present results should be relevant for plasma physics, astrophysical observations, synchrotrons, and other environments with fast moving electrons.
description: Submitted to PRD
Tracing the Emergent Field of Digital Environmental and Climate Activism Research: A Mixed-Methods Systematic Literature Review
Creators: name: Baran, Zozan
name: Stoltenberg, Daniela
Publisher: name: Freie Universität Berlin
Year: 2023
Subjects: subject: Activism
subject: climate change
subject: digital media
subject: environmentalism
subject: systematic literature review
subject: 500 Naturwissenschaften und Mathematik::550 Geowissenschaften, Geologie::550 Geowissenschaften

description: Following Fridays for Future’s transnational mobilization, research into digital environmental and climate activism has rapidly grown. We contribute to the solidification of this emerging field through a mixed-methods systematic literature review. We quantitatively analyze 138 peer-reviewed articles regarding their theories, methodologies, and empirical focus. To identify research trajectories and emerging fields of interest, we add an in-depth qualitative analysis of influential publications. Research interest has grown rapidly and shifted from various areas of environmental grievance towards climate change as the primary focus. The field is driven by theories of framing, connective action, and (in)visibility. It is methodologically diverse, but geographically biased towards the West. Popular approaches include ethnographic case studies and Twitter studies, while other platforms receive limited attention. We diagnose a need for more comparative and relational approaches going beyond individual cases, countries, and platforms.
LEVERAGING MULTIMODAL SENSING FOR ENHANCING THE SECURITY AND PRIVACY OF MOBILE SYSTEMS
Creators: name: Farrukh, Habiba
Publisher: name: Purdue University Graduate School
Year: 2023
Subjects: System and network security
Mobile computing
Data and information privacy

description: Mobile systems, such as smartphones, wearables (e.g., smartwatches, AR/VR headsets),
 and IoT devices, have come a long way from being just a method of communication to
 sophisticated sensing devices that monitor and control several aspects of our lives. These
 devices have enabled several useful applications in a wide range of domains ranging from
 healthcare and finance to energy and agriculture industries. While such advancement has
 enabled applications in several aspects of human life, it has also made these devices an
 interesting target for adversaries.
 In this dissertation, I specifically focus on how the various sensors on mobile devices can
 be exploited by adversaries to violate users’ privacy and present methods to use sensors
 to improve the security of these devices. My thesis posits that multi-modal sensing can be
 leveraged to enhance the security and privacy of mobile systems.
 In this, first, I describe my work that demonstrates that human interaction with mobile de-
 vices and their accessories (e.g., stylus pencils) generates identifiable patterns in permissionless
 mobile sensors’ data, which reveal sensitive information about users. Specifically, I developed
 S3 to show how embedded magnets in stylus pencils impact the mobile magnetometer sensor
 and can be exploited to infer a users incredibly private handwriting. Then, I designed LocIn
 to infer a users indoor semantic location from 3D spatial data collected by mixed reality
 devices through LiDAR and depth sensors. These works highlight new privacy issues due to
 advanced sensors on emerging commodity devices.
 Second, I present my work that characterizes the threats against smartphone authentication
 and IoT device pairing and proposes usable and secure methods to protect against these threats.
 I developed two systems, FaceRevelio and IoTCupid, to enable reliable and secure user and
 device authentication, respectively, to protect users’ private information (e.g., contacts,
 messages, credit card details) on commodity mobile and allow secure communication between
 IoT devices. These works enable usable authentication on diverse mobile and IoT devices
 and eliminate the dependency on sophisticated hardware for user-friendly authentication.
title: Παρουσία μικροβίων ανθεκτικών στα αντιβιοτικά στο πόσιμο νερό : Η επίδραση στη δημόσια υγεία
title: Antibiotic resistant microorganisms in drinking water ; The impact in public health
titleType: AlternativeTitle
Creators: name: Ξενοπούλου, Ευαγγελία
Publisher: name: Πανεπιστήμιο Δυτικής Αττικής
Year: 2021
Subjects: Πόσιμο νερό
Αντιμικροβιακή αντοχή
Drinking water
Antimicrobial resistance
Δημόσια υγεία
Public health

description: Η αντιμικροβιακή αντοχή τις τελευταίες δύο δεκαετίες αποτελεί παγκόσμια απειλή για τη δημόσια υγεία. Από την εποχή της ανακάλυψης των πρώτων αντιβιοτικών, τα οποία πρόσφεραν αδιαμφισβήτητα οφέλη στην ιατρική, η αλόγιστη και η υπερβολική χρήση των αντιμικροβιακών στην κτηνιατρική και την ιατρική έχουν επιταχύνει το παγκοσμίως αυξανόμενο φαινόμενο της αντιμικροβιακής αντοχής (1). Τα αντιβιοτικά έχουν γίνει ρυπογόνοι παράγοντες για το περιβάλλον μαζί με τα γονίδια που σχετίζονται με την αντιμικροβιακή αντοχή. Η έρευνα έχει δείξει ότι αυτοί οι παράγοντες μόλυνσης είναι επίμονοι και αρκετά κινητικοί ώστε να μεταφέρονται από τα υγρά απόβλητα, τις φάρμες και τα αγροτικά απόβλητα στα φυσικά νερά και έχει επίσης φανεί η δυνατότητά τους να αποτελέσουν μακροπρόθεσμα απειλή για το περιβάλλον, για την υγεία των ανθρώπων και των ζώων. Σε πολλές χώρες τα υπόγεια ύδατα αποτελούν πηγή πόσιμου νερού. Τα αστικά ύδατα είναι ιδιαιτέρως ευάλωτα στη μόλυνση από ανθρώπινους παράγοντες εξαιτίας των έντονων αστικών δραστηριοτήτων και της βιομηχανίας (2). Ο αστικός κύκλος του νερού, ο οποίος περιλαμβάνει την αποστράγγιση του νερού, την απολύμανση και τη διανομή για την κατανάλωση από τους ανθρώπους, και η συλλογή, επεξεργασία και μεταφορά των αποβλήτων στο περιβάλλον παρουσιάζει ιδιαίτερο ενδιαφέρον για την πορεία της αντιμικροβιακής αντοχής στο περιβάλλον και για την εκτίμηση των κινδύνων της μετάδοσής της στους ανθρώπους (3). Η παρουσία μικροβίων ανθεκτικών στα αντιβιοτικά στo πόσιμο νερό και η επίδρασή τους στη δημόσια υγεία αποτελεί και το αντικείμενο αυτής της εργασίας. Από την ανασκόπηση της βιβλιογραφίας προκύπτει η σημασία που έχει το θέμα παγκοσμίως, καθώς και η ανάγκη να εφαρμοστούν συντονισμένες προσπάθειες για την αντιμετώπισή του στα πλαίσια της Ενιαίας Υγείας. Οι Ευρωπαϊκοί και παγκόσμιοι οργανισμοί έχουν θεσπίσει τα πλαίσια δράσης και τις κατευθυντήριες γραμμές. Ωστόσο, υπάρχει ανάγκη για πιο αποτελεσματικά προληπτικά μέτρα για την ελάττωση της χρήσης των αντιβιοτικών, την πιο εντατική επιτήρηση της αντιμικροβιακής αντοχής, την αύξηση των γνώσεων γύρω από τα ανθεκτικά μικρόβια και την ευαισθητοποίηση όλων των εμπλεκόμενων στο θέμα. Κατά την πανδημία της Covid-19 παρατηρείται όξυνση του προβλήματος λόγω της αύξησης της χρήσης αντιβιοτικών και αντιμικροβιακών.
Reconstruction of 7T-Like Images From 3T MRI
Creators: name: Shin, Hae Won
name: Shen, Dinggang
name: Zong, Xiaopeng
name: Shi, Feng
name: An, Hongyu
name: Bahrami, Khosro
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2016

description: In the recent MRI scanning, ultra-high-field (7T) MR imaging provides higher resolution and better tissue contrast compared to routine 3T MRI, which may help in more accurate and early brain diseases diagnosis. However, currently, 7T MRI scanners are more expensive and less available at clinical and research centers. These motivate us to propose a method for the reconstruction of images close to the quality of 7T MRI, called 7T-like images, from 3T MRI, to improve the quality in terms of resolution and contrast. By doing so, the post-processing tasks, such as tissue segmentation, can be done more accurately and brain tissues details can be seen with higher resolution and contrast. To do this, we have acquired a unique dataset which includes paired 3T and 7T images scanned from same subjects, and then propose a hierarchical reconstruction based on group sparsity in a novel multi-level Canonical Correlation Analysis (CCA) space, to improve the quality of 3T MR image to be 7T-like MRI. First, overlapping patches are extracted from the input 3T MR image. Then, by extracting the most similar patches from all the aligned 3T and 7T images in the training set, the paired 3T and 7T dictionaries are constructed for each patch. It is worth noting that, for the training, we use pairs of 3T and 7T MR images from each training subject. Then, we propose multi-level CCA to map the paired 3T and 7T patch sets to a common space to increase their correlations. In such space, each input 3T MRI patch is sparsely represented by the 3T dictionary and then the obtained sparse coefficients are used together with the corresponding 7T dictionary to reconstruct the 7T-like patch. Also, to have the structural consistency between adjacent patches, the group sparsity is employed. This reconstruction is performed with changing patch sizes in a hierarchical framework. Experiments have been done using 13 subjects with both 3T and 7T MR images. The results show that our method outperforms previous methods and is able to recover better structural details. Also, to place our proposed method in a medical application context, we evaluated the influence of post-processing methods such as brain tissue segmentation on the reconstructed 7T-like MR images. Results show that our 7T-like images lead to higher accuracy in segmentation of white matter (WM), gray matter (GM), cerebrospinal fluid (CSF), and skull, compared to segmentation of 3T MR images.
ALMA imaging of SDP.81 - II. A pixelated reconstruction of the CO emission lines
Creators: name: Rybak, M.
name: Vegetti, S.
name: McKean, J. P.
name: Andreani, P.
name: White, S. D. M.
Publisher: name: arXiv
Year: 2015
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We present a sub-100 pc-scale analysis of the CO molecular gas emission and kinematics of the gravitational lens system SDP.81 at redshift 3.042 using Atacama Large Millimetre/submillimetre Array (ALMA) science verification data and a visibility-plane lens reconstruction technique. We find clear evidence for an excitation dependent structure in the unlensed molecular gas distribution, with emission in CO (5-4) being significantly more diffuse and structured than in CO (8-7). The intrinsic line luminosity ratio is r_8-7/5-4 = 0.30 +/- 0.04, which is consistent with other low-excitation starbursts at z ~ 3. An analysis of the velocity fields shows evidence for a star-forming disk with multiple velocity components that is consistent with a merger/post-coalescence merger scenario, and a dynamical mass of M(< 1.56 kpc) = 1.6 +/- 0.6 x 10^10 M_sol . Source reconstructions from ALMA and the Hubble Space Telescope show that the stellar component is offset from the molecular gas and dust components. Together with Karl G. Jansky Very Large Array CO (1-0) data, they provide corroborative evidence for a complex ~2 kpc-scale starburst that is embedded within a larger ~15 kpc structure.
description: MNRAS accepted, 6th July 2015
Four and one more: The formation history and total mass of globular clusters in the Fornax dSph
Creators: name: de Boer, T. J. L.
name: Fraser, M.
Publisher: name: arXiv
Year: 2015
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We have determined the detailed star formation history and total mass of the globular clusters in the Fornax dwarf spheroidal using archival HST WFPC2 data. Colour magnitude diagrams are constructed in the F555W and F814W bands and corrected for the effect of Fornax field star contamination, after which we use the routine Talos to derive the quantitative star formation history as a function of age and metallicity. The star formation history of the Fornax globular clusters shows that Fornax 1, 2, 3 and 5 are all dominated by ancient (>10 Gyr) populations. Cluster Fornax 1,2 and 3 display metallicities as low as [Fe/H]=-2.5 while Fornax 5 is slightly more metal-rich at [Fe/H]=-1.8, consistent with resolved and unresolved metallicity tracers. Conversely, Fornax 4 is dominated by a more metal-rich~([Fe/H]=-1.2) and younger population at 10 Gyr, inconsistent with the other clusters. A lack of stellar populations overlapping with the main body of Fornax argues against the nucleus cluster scenario for Fornax 4. The combined stellar mass in globular clusters as derived from the SFH is (9.57$\pm$0.93)$\times$10$^{5}$ M$_{\odot}$ which corresponds to 2.5$\pm$0.2 percent of the total stellar mass in Fornax. The mass of the four most metal-poor clusters can be further compared to the metal-poor Fornax field to yield a mass fraction of 19.6$\pm$3.1 percent. Therefore, the SFH results provide separate supporting evidence for the unusually high mass fraction of the GCs compared to the Fornax field population.
description: 11 pages, 11 figures. Accepted in A&A
Deformed hyperbolic black holes
Creators: name: Chen, Yu
name: Lim, Yen-Kheng
name: Teo, Edward
Publisher: name: arXiv
Year: 2015
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: Black holes with planar or hyperbolic horizons are known to exist in AdS space, alongside the usual ones with spherical horizons. In this paper, we consider a one-parameter generalisation of these black holes that is contained in the AdS C-metric. In terms of the domain-structure analysis recently developed for such solutions, these black holes have a domain in the shape of a triangle. It is shown that the horizons of these black holes are deformed hyperbolic spaces, with the new parameter controlling the amount of deformation. The space-times are static and completely regular outside the horizons. We argue that these black holes are hyperbolic analogues of the "slowly accelerating" spherical black holes known to exist in AdS space.
description: 36 pages, 12 figures; v3: added discussion; as accepted for publication in Phys. Rev. D
Long Baseline Bistatic Radar
Creators: name: Garrington, Simon
Publisher: name: Zenodo
Year: 2023

description: Long-baseline Bistatic Radar combines existing radar transmitters and sensitive radio telescopes to improve the capabilities of radar for space debris, space domain awareness, calibration satellites and potentially more distant objects such as asteroids. The enhanced sensitivity from using large radio telescopes with cryogenic receivers is especially relevant at GEO and beyond. We have demonstrated the technique at L-band using transmitters at MIT (Haystack, US) and TIRA (Bonn) and radio telescopes in Europe, including e-MERLIN, WSRT and SRT. Results include precision differential measurements of satellite clusters and micro-Doppler characterisation of tumbling debris objects, allowing image reconstruction for rocket bodies in ~20,000km orbit. Other applications and extensions of the technique will be discussed.
Spin density wave instabilities in the NbS2 monolayer
Creators: name: Güller, F.
name: Vildosola, V. L.
name: Llois, A. M.
Publisher: name: arXiv
Year: 2015
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: In the present work, we study the magnetic properties of the NbS2 monolayer by first-principles calculations. The transition metal dichalcogenides (TMDC) are a family of laminar materials presenting exciting properties such as charge density waves (CDW), superconductivity and metal-insulating transitions among others. 2H-NbS2 is a particular case within the family, because it is the only one that is superconductor without exhibiting a CDW order. Although no long range magnetic order was experimentally observed in the TMDC, we show here that the single monolayer of NbS2 is on the verge of a spin density wave (SDW) phase. Our calculations indicate that a wave-like magnetic order is stabilized in the NbS2 monolayer in the presence of magnetic defects or within zig-zag nanoribbons, due to the presence of unpaired electrons. We calculate the real part of the bare electronic susceptibilty and the corresponding nesting function of the clean NbS2 monolayer, showing that there are strong electronic instabilities at the same wavevector asociated with the calculated SDWs, also corresponding with one of the main nesting vectors of the Fermi surface. We conclude that the physical mechanism behind the spin-wave instabilities are the nesting properties, accentuated by the quasi 2D character of this system, and the rather strong Coulomb interactions of the 4d band of the Nb atom. We also estimate the amplitude of the spin-fluctuations and find that they are rather large, as expected for a system on the verge of a quantum critical transition.