cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
The limits of multifunctionality in tunable networks
Creators: name: Rocks, Jason W.
name: Ronellenfitsch, Henrik
name: Liu, Andrea J.
name: Nagel, Sidney R.
name: Katifori, Eleni
Publisher: name: arXiv
Year: 2018
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: Physics and Society (physics.soc-ph)
subject: FOS: Physical sciences

description: Nature is rife with networks that are functionally optimized to propagate inputs in order to perform specific tasks. Whether via genetic evolution or dynamic adaptation, many networks create functionality by locally tuning interactions between nodes. Here we explore this behavior in two contexts: strain propagation in mechanical networks and pressure redistribution in flow networks. By adding and removing links, we are able to optimize both types of networks to perform specific functions. We define a single function as a tuned response of a single "target" link when another, predetermined part of the network is activated. Using network structures generated via such optimization, we investigate how many simultaneous functions such networks can be programmed to fulfill. We find that both flow and mechanical networks display qualitatively similar phase transitions in the number of targets that can be tuned, along with the same robust finite-size scaling behavior. We discuss how these properties can be understood in the context of a new class of constraint-satisfaction problems.
description: 37 pages (single column), 14 figures, 1 table. J.W.R. and H.R. contributed equally to this work
Risikofaktoren und Therapieoptionen zur Behandlung des Sekundärglaukoms nach Radiatio uvealer Melanome mittels Protonentherapie
Creators: name: Riechardt, Aline Isabel
Publisher: name: Charité - Universitätsmedizin Berlin
Year: 2021
Subjects: subject: uveal melanoma
subject: proton therapy
subject: secondary glaucoma
subject: 600 Technik, Medizin, angewandte Wissenschaften::610 Medizin und Gesundheit::610 Medizin und Gesundheit

description: Das uveale Melanom ist eine sowohl visus- als auch lebensbedrohende Erkrankung. Erfreulicherweise hat sich in den letzten zehn Jahren unser Verständnis, insbesondere bezüglich der Genetik der uvealen Melanome, deutlich entwickelt und es bleibt zu hoffen, dass basierend auf diesen Erkenntnissen neue therapeutische Verfahren zur Behandlung des metastasierten uvealen Melanoms entstehen werden. Bei der Behandlung des Primärtumors sind wir derzeit in der Lage Tumore in einer Größenordnung zu bestrahlen, die früher eine sichere Indikation zur Enukleation dargestellt hätten. Hierzu sind zum Teil aufwändige Operationen und insbesondere während der ersten Jahre engmaschige Kontrollen notwendig, um etwaige Spätfolgen einer Radiatio rechtzeitig zu erkennen und zu behandeln. Die lokale Tumorkontrollrate mittels Protonentherapie ist mit 95-98 % so hoch, dass der häufigste Grund für eine sekundäre Enukleation meist nicht das Lokalrezidiv darstellt, sondern bestrahlungsbedingte Komplikationen, allen voran das Sekundärglaukom. In dieser Arbeit sollen daher die Risikofaktoren, die zur Entwicklung der Sekundärglaukome führen können, sowie mögliche prophylaktische Interventionen und Behandlungsoptionen erörtert werden.
Starburst in the Intragroup Medium of Stephan's Quintet
Creators: name: Xu, Cong
name: Tuffs, Richard
Publisher: name: arXiv
Year: 1998
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Based on new ISO mid-infrared observations and ground based $H_α$ and near-infrared observations, we report the detection of a bright starburst in the intragroup medium (IGM) of the famous compact group of galaxies Stephan's Quintet (Source A in Fig.1). We demonstrate that this starburst is caused by a collision between a high velocity ($δ$V$\sim$ 1000 km/sec) intruder galaxy (NGC7318b) and the IGM of the group. While this is the only starburst known today that is induced by a galaxy/cold-intergalactic-medium collision, it provides new constraints to the theory for interaction-induced starbursts, and may hint at a new mechanism for the star formation excess seen in more distant clusters.
description: 17 pages, 2 PS figures. Accepted by ApJ
Checklist of good practices in using Open Journal Systems software (OJS) for journal editing and publishing
Creators: name: Kuchma, Iryna
name: Ševkušić, Milica
Publisher: name: Zenodo
Year: 2023

description: This is an updated and revised version of our checklist to support editors and publishers of open access journals using Open Journals Systems (OJS) software. OJS is created by the Public Knowledge Project (PKP), which is a multi-university initiative developing free and open source software to improve the quality and reach of scholarly publishing.

The checklist includes an overview of the latest release of OJS 3 (OJS 3.4.0-4 released on November 17, 2023) and tips on software plugins, journal procedures and policies, system security, usage statistics, and suggestions for improving content accessibility, visibility and discoverability. It also includes a section about indexing your journals in DOAJ (Directory of Open Access Journals) and recommendations for further reading.
The influence of microparticles at the air - liquid interface on the pinch - off, oscillation and coalescence of bubbles
Creators: name: Wang, Hao
Publisher: name: Imperial College London
Year: 2020

description: Surface tension is one of the most important physical properties that determines the behaviour of bubbles. While the effect of nanoparticles and surfactants on the surface tension of bubbles have been widely studied, the role of microparticles has not received too much attention. In this work, the effect of silica microparticles on the surface tension and the behaviour of bubbles was explored, both for bubbles at rest and during dynamic processes such as pinch-off, oscillation and coalescence. The influence of microparticles on the shape and surface tension of static bub- bles grown from a submerged nozzle was investigated first using a modified sessile bubble method. The results show that particles were in static equilibrium at the static bubble, without any change in bubble surface tension. In addition, it was found that the presence of particles at the bubble interface led to a change in the bubble contour, similar to the effect of the changes in surface tension for uncoated bubbles, which explains why classical sessile bubble tensiometry overestimated the surface tension of particle-laden bubbles. Secondly, the influence of microparticles on the surface tension and shape defor- mation during and immediately after pinch-off was investigated. It was found that microparticles at the deforming air-liquid interfaces generated surface pressure and reduced surface tension of the interfaces, leading to a hindered shape deformation compared to that of uncoated bubbles. Moreover, it was found that changing bubble surface coverage has noticeable effect on the surface pressure after pinch-off, while not during pinch-off. In addition, increasing particle contact angle and particle size both led to an increase in the surface pressure during pinch-off. Experiments on bub- ble oscillations were conducted, harmonic analysis shows the presence of particles at bubble surfaces decreased the damping rate of the dominant harmonic signifi- cantly while having a minor influence on the oscillation frequency during the shape oscillation of the bubbles. Lastly, the influence of microparticles on the surface tension and the neck growth dynamics during the early stage of bubble coalescence was studied. Results show that the particles at the bubble surface hindered the neck growth dynamics due to the generation of the surface pressure by particle interactions. The existence of the surface pressure lead to a lower surface tension compared to that of the uncoated bubbles, with coarser particles generating higher surface pressure and correspond- ing to lower surface tension.This thesis provided a systematic study of the behaviour of particle-laden bub- bles using high-speed photography, macrophotography and image analysis tech- niques. This work contributes to fundamental understanding of the surface tension of particle-laden interfaces both on and off equilibrium.
Wave Motions In Molecular Clouds: Results in Two Dimensions
Creators: name: Gehman, Curtis S.
name: Adams, Fred C.
name: Fatuzzo, Marco
name: Watkins, Richard
Publisher: name: arXiv
Year: 1995
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We study the linear evolution of small perturbations in self-gravitating fluid systems in two spatial dimensions; we consider both cylindrical and cartesian (i.e., slab) geometries. The treatment is general, but the application is to molecular clouds. We consider a class of equations of state which heuristically take into account the presence of turbulence; in particular, we consider equations of state which are {\it softer} than isothermal. We take the unperturbed cloud configuration to be in hydrostatic equilibrium. We find a class of wave solutions which propagate along a pressure supported cylinder (or slab) and have finite (trapped) spatial distributions in the direction perpendicular to the direction of propagation. Our results indicate that the dispersion relations for these two dimensional waves have similar forms for the two geometries considered here. Both cases possess a regime of instability and a fastest growing mode. We also find the (perpendicular) form of the perturbations for a wide range of wavelengths. Finally, we discuss the implications of our results for star formation and molecular clouds. The mass scales set by instabilities in both molecular cloud filaments and sheets are generally much larger than the masses of stars. However, these instabilities can determine the length scales for the initial conditions for protostellar collapse.
description: 24 pages + 10 figures; self-extracting, uuencoded, compressed tarfile
Performance of the optimized Post-Zel'dovich approximation for CDM models in arbitrary FLRW cosmologies
Creators: name: Hamana, Takashi
Publisher: name: arXiv
Year: 1998
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We investigate the performance of the optimized Post-Zel'dovich approximation in three cold dark matter cosmologies. We consider two flat models with $Ω_0=1$ (SCDM) and with $Ω_0=0.3$ ($Λ$CDM) and an open model with $Ω_0=0.3$ (OCDM). We find that the optimization scheme proposed by Weiß, Gottlöber & Buchert (1996), in which the performance of the Lagrangian perturbation theory was optimized only for the Einstein-de Sitter cosmology, shows the excellent performances not only for SCDM model but also for both OCDM and $Λ$CDM models. This universality of the excellent performance of the optimized Post-Zel'dovich approximation is explained by the fact that a relation between the Post-Zel'dovich order's growth factor $E(a)$ and Zel'dovich order's one $D(a)$, $E(a)/D^2(a)$, is insensitive to the background cosmologies.
description: 8 pages, 3 figures, LaTex using aaspp4.sty and epsf.sty, Accepted for publication in ApJ Letters
Effects of Sampling on Measuring Galaxy Count Probabilities
Creators: name: Szapudi, István
name: Szalay, Alexander S.
Publisher: name: arXiv
Year: 1995
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We investigate in detail the effects of sampling on our ability to accurately reconstruct the distribution of galaxies from galaxy surveys. We use a simple probability theory approach, Bayesian classifier theory and Bayesian transition probabilities. We find the best Bayesian estimator for the case of low sampling rates, and show that even in the optimal case certain higher order characteristics of the distribution are irretrievably washed out by sparse sampling: we illustrate this by a simple model for cluster selection. We show that even choosing an optimal threshold, there are nonzero numbers for both misidentified clusters and true clusters missed. The introduction of sampling has an effect on the distribution function that is similar to convolution. Deconvolution is possible and given in the paper, although it might become unstable as sampling rates become low. These findings have important consequences on planning and strategies of future galaxy surveys.
description: Accepted for publication in ApJ. postscript of 16 pages and three figures uuencoded, gzipped, tarred
Hot white dwarfs and the UV delay in dwarf novae
Creators: name: Hameury, J. -M.
name: Lasota, J. -P.
name: Dubus, G.
Publisher: name: arXiv
Year: 1998
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We calculate the effect of illumination of dwarf nova accretion discs by radiation from a hot, central, white dwarf. We show that only for very hot white dwarfs (Teff ~ 40 000$ K) the inner region of quiescent dwarf nova discs are partially depleted so that the delay between the rise to outburst of the optical and UV fluxes would be increased as suggested recently by King (1997). This depletion, however, must create several small outbursts between main outbursts, contrary to observations. Lower white dwarf temperatures may cause the outburts to be of the `inside-out' type removing the UV delay. We conclude that white dwarf irradiation of dwarf nova discs is not very efficient for example because the UV radiation from the hot white dwarf does not penetrate deep enough in the disc atmosphere. The total ablation of the inner disc by e.g. evaporation (possibly related to illumination) appears to be a very promising possibility, accounting for both the EUV delay and the general lightcurves properties.
description: 6 pages, 8 figures; accepted for publication in MNRAS
Light-matter interactions in lossy and lossless media
Creators: name: Cambiasso, Javier
Publisher: name: Imperial College London
Year: 2017

description: Light-matter interactions lie at the core of modern technologies. Different decay channels get activated depending on the structure of matter used and on the properties of the exciting light. In particular, nano-antennas are used as the quintessential object to redistribute the energy of single-photon emitters in the nano-scale or of free-electrons oscillations in metals. Two different kind of nano-antennas are studied: metallic (lossy) and dielectric (lossless). Metallic nano-antennas are shown to be applicable to technologies benefiting from enhancement of both radiative and non-radiative properties. In stark contrast, certain dielectric nano-antennas are essentially lossless in the visible regime, which benefits their coupling to far-field modes. The metallic nano-antennas used in this work are either asymmetric nano-cavities or the ubiquitous bow-tie antenna. With the former we show enhancement of the radiative rate of single photon emitters located in the neighbourhood of the strongly modified electromagnetic environment. Here, two competing processes collude to either enhance or quench the coupling to the far-field. As will be shown via simulations, these two scenarios are strongly wavelength dependent and two very differentiated regions can be recognised where one overwhelms the other. Contrariwise, the bow-tie antennas are used to enhance the opposite effect: non-radiative channels exclusively. Here it is experimentally demonstrated that surface plasmon polaritons excited in the nano-structure can decay into hot carriers, instead of far-field radiation. A sub-diffraction mapping of the rate of hot electron generation is traced by depositing nano-particles and analysing many scanning electron micrographs. In order to show that nano-photonics also has the potential to get rid of losses, we investigated the possibility of applying gallium phosphide nano-antennas as efficient far-field out-couplers. A comparison between metallic and dielectric nano-antennas is carried out using a unified theory and finally experimental results corroborate the large enhancement predicted by the theory of the fluorescence rate of single-photon emitters located around the scatterers
Mist Flow Visualization for Round Jets in Aerosol Jet Printing
Creators: name: Feng, James Q.
Publisher: name: arXiv
Year: 2018
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: With the microdroplets of water serving as light scattering particles, the mist flow patterns of round micro-jets can be visualized using the Aerosol Jet(R) direct-write system. The visualization images show that the laminar mist jet appears to extend to more than 20 times the diameter of nozzle orifice, D, for jet Reynolds number Re < 600, especially with D = 0.3 mm and less. For smaller jets (e.g., with D = 0.15 mm), laminar collimated mist flow might be retained to 40xD for Re < 600 and for Re ~ 1500 within 20xD from the nozzle. The laminar part of mist flow associated with larger jets (e.g., with D = 1.0 mm for Re < 600) tends to exhibit noticeable gradual widening due to viscous diffusion. For free jets, their breakdown length--the distance from nozzle where transition from laminar to turbulent mist flow takes place as signaled by the inception of a rapid widening of mist stream--is shown to decrease with increasing Re. The presence of impingement wall tends to prevent turbulence development, even when the wall is placed further downstream of the free-jet breakdown length for a given Re . The critical Re for an impinging jet to develop turbulence increases as the standoff S is reduced. The mist flow of impinging jet of D = 1.0 mm seems to remain laminar even for Re > 4000 at S = 12 mm.
description: 12 pages, 10 figures
Facile and rapid synthesis of piperidinium-6-amino-4-aryl-3, 5-dicyano-1,4-dihydropyridine-2-thiolate
Creators: name: Fahimeh Sadat Hosseini
name: Bayat, Mohammad
name: Masoumi, Milad
Publisher: name: Taylor & Francis
Year: 2018
Subjects: subject: Biochemistry
subject: Medicine
subject: Molecular Biology
subject: Neuroscience
subject: Biotechnology
subject: 39999 Chemical Sciences not elsewhere classified
subject: FOS: Chemical sciences
subject: 80699 Information Systems not elsewhere classified
subject: FOS: Computer and information sciences
subject: 111714 Mental Health
subject: FOS: Health sciences
subject: 110309 Infectious Diseases
subject: 60506 Virology
subject: FOS: Biological sciences

description: A fast and convenient protocol for the synthesis of a new class of piperidin-1-ium 6-amino-4-aryl-3,5-dicyano-1,4-dihydropyridine-2-thiolate (piperidinium salt) derivatives is developed by the one-pot, three-component reactions of cyanothioacetamide, aromatic aldehydes and piperidine in dichloromethane at room temperature. The features such as operational simplicity, mild conditions, absence of catalyst, high yields in short reaction times, simple purification process with no chromatographic technique make the protocol highly attractive.
Statistics of Peculiar Velocities from Cosmic Strings
Creators: name: Moessner, R.
Publisher: name: arXiv
Year: 1995
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We calculate the probability distribution of a single component of peculiar velocities due to cosmic strings, smoothed over regions with a radius of several $h^{-1}$ Mpc. The probability distribution is shown to be Gaussian to good accuracy, in agreement with the distribution of peculiar velocities deduced from the 1.9 Jy IRAS redshift survey. Using the normalization of parameters of the cosmic string model from CMB measurements, we show that the rms values for peculiar velocities inferred from IRAS are consistent with the cosmic string model provided that long strings have some small-scale structure.
description: 17 pages, uses Latex, to appear in MNRAS, 1 Postscript figure available on request
Critical behaviour of random diffeomorphisms: quasi-stationary measures and escape times
Creators: name: Olicon Mendez, Guillermo
Publisher: name: Imperial College London
Year: 2020

description: In this thesis we consider discrete-time dynamical systems in the interval perturbed with bounded noise near a bifurcation of a minimal invariant set, its relation with stationary and quasi-stationary measures, and its asymptotic behaviour as the parameters tend to the bifurcation point. First, we study existence and uniqueness of stationary measures on minimal invariant sets, and its approximation with the transition probabilities of the system. We derive analogous results for the unique stationary density, and conclude that the system exhibits exponential decay of (annhealed) correlations. We further study the shape of the stationary density near the boundary of its support, and relate it to the hyperbolicity of the the boundary point for the so-called extremal maps. Secondly, we study a similar problem for quasi-stationary measures supported on a metastable set, when the parameters are close to a bifurcation point. We prove existence and uniqueness of quasi-stationary measures, and the exponential convergence of conditional transition probabilities of the system towards this measure. We study the asymptotic behaviour of the mean escape time from the metastable region as the parameter tends to the bifurcation point. The results here presented relate the bifurcation theory of dynamical systems under bounded noisy perturbations, with their statistical features. To our knowledge these are among the first of their kind.
A framework for recognising the value proposition of CO2 capture and storage technologies
Creators: name: Pereira Cabral, Renato Manuel
Publisher: name: Imperial College London
Year: 2021

description: Carbon capture and storage (CCS) technologies are considered the most cost-effective means of curbing anthropogenic carbon dioxide (CO2) emissions from both the power and industrial sectors at a system level. Indeed, several studies consider CCS essential to limit global warming below 1.5°C by 2050 and curb the impacts of climate change. However, this technology is prohibitively expensive without government subsidies relative to unabated plants. In this thesis, oxy-fuel combustion was used as a model CCS technology to develop cost-reduction frameworks. Process inefficiencies were analysed using the first and second laws of thermodynamics and the process was improved via a heat integration strategy. This strategy improved the efficiency of an oxy-combustion process whilst reducing its capital cost. A solvent-based capture unit was proposed to substitute the gas processing unit (GPU) and its key performance indicators were compared with the traditional GPU. However, cryogenic methods to process the flue gas from oxy-combustion are still superior, providing comparable capture rates and CO2 purity at lower costs. A framework to value negative emissions from bioenergy with CCS (BECCS) was proposed to simultaneously decarbonise the power and industrial sectors. However, the high CO2 price required to generate profits from auctioning negative emission credits makes this framework unlikely to be implemented. Lastly, the flexible operation of a CCS plant to take advantage of the daily electricity price variation was evaluated. The flexible operation of a plant with liquid oxygen storage depends upon the region it operates as electricity price fluctuation plays a critical role in its profitability. There is potential to significantly reduce CCS costs by the concurrent application of several approaches. The general nature of most of the framework developed in this thesis means that they can be applied in other CCS processes, such as post- or pre-combustion capture.
ESM5 - ESM8 are PDF versions of the maple worksheets ESM1 - ESM4 respectively. from Determination of the instantaneous geostrophic flow within the three-dimensional magnetostrophic regime
Creators: name: Hardy, Colin M.
name: Livermore, Philip W.
name: Jitse Niesen
name: Jiawen Luo
name: Li, Kuan
Publisher: name: The Royal Society
Year: 2018
Subjects: subject: Geophysics
subject: FOS: Earth and related environmental sciences
subject: 91504 Fluidisation and Fluid Mechanics
subject: FOS: Other engineering and technologies
subject: 10299 Applied Mathematics not elsewhere classified
subject: FOS: Mathematics

description: In his seminal work, Taylor (1963 Proc. R. Soc. Lond. A 9, 274–283. (doi:10.1098/rspa.1963.0130).) argued that the geophysically relevant limit for dynamo action within the outer core is one of negligibly small inertia and viscosity in the magnetohydrodynamic equations. Within this limit, he showed the existence of a necessary condition, now well known as Taylor's constraint, which requires that the cylindrically averaged Lorentz torque must everywhere vanish; magnetic fields that satisfy this condition are termed Taylor states. Taylor further showed that the requirement of this constraint being continuously satisfied through time prescribes the evolution of the geostrophic flow, the cylindrically averaged azimuthal flow. We show that Taylor's original prescription for the geostrophic flow, as satisfying a given second-order ordinary differential equation, is only valid for a small subset of Taylor states. An incomplete treatment of the boundary conditions renders his equation generally incorrect. Here, by taking proper account of the boundaries, we describe a generalization of Taylor's method that enables correct evaluation of the instantaneous geostrophic flow for any three-dimensional Taylor state. We present the first full-sphere examples of geostrophic flows driven by non-axisymmetric Taylor states. Although in axisymmetry the geostrophic flow admits a mild logarithmic singularity on the rotation axis, in the fully three-dimensional case we show that this is absent and indeed the geostrophic flow appears to be everywhere regular.
Organised natural structures using synthetic biology
Creators: name: Pothoulakis, Georgios
Publisher: name: Imperial College London
Year: 2016

description: Pattern formation is found widely throughout nature serving important roles in many different biological contexts. Multicellular organisms form patterns to enable new functions and pattern formation is also a crucial step for biological adaptation. The work presented here lays the foundations for the creation and control of multicellular growth patterns with a normally single-celled organism. The natural capacity for strains of Saccharomyces cerevisiae yeast to perform multicellular growth is here genetically and externally-controlled using synthetic biology tools. This allows S. cerevisiae grow in multicellular filamenting patterns, following a unique phenotype called pseudohyphal growth. Fine-control of the dynamic behaviour and gene expression of a colony of cells growing with this phenotype should enable fractal-like growth formations to be genetically-encoded. In this work, synthetic gene regulatory networks were first constructed in order to control genetic targets than induce or repress the pseudohyphal growth phenotype. This generated haploid and diploid yeast strains that can quickly switch to growing as filaments when simple chemical stimuli are externally provided or removed. In order to enable control over pattern formation with these strains, further genetic targets such as the BUD genes were investigated and the pseudohyphal growth phenotype was linked to previously described timer gene regulatory networks that dynamically change the expression of target genes over hours and days. These timer networks allowed cells to be programmed to transition from pseudohyphal growth back to normal yeast growth as the cells are grown in a colony over days. Finally, in an attempt to create controlled growth from pseudohyphal yeast so that fractal-like patterns could be made, new hybrid promoters with multiple modes of regulation were generated. These externally-inducible promoters were constructed to only express in mother cells after they have budded a daughter cell, and were designed in order to control how often filaments form new branches when S. cerevisiae grows in pseudohyphal form. While a full integration of the whole system to generate controllable fractal-like patterns was not achieved in the end, this study delivers several valuable new tools for yeast research and yeast synthetic biology.
Cooling by Cooper pair splitting
Creators: name: Sánchez, Rafael
name: Burset, Pablo
name: Yeyati, Alfredo Levy
Publisher: name: arXiv
Year: 2018
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: The electrons forming a Cooper pair in a superconductor can be spatially separated preserving their spin entanglement by means of quantum dots coupled to both the superconductor and independent normal leads. We investigate the thermoelectric properties of such a Cooper pair splitter and demonstrate that cooling of a reservoir is an indication of non-local correlations induced by the entangled electron pairs. Moreover, we show that the device can be operated as a non-local thermoelectric heat engine. Both as a refrigerator and as a heat engine, the Cooper pair splitter reaches efficiencies close to the thermodynamic bounds. As such, our work introduces an experimentally accessible heat engine and a refrigerator driven by entangled electron pairs in which the role of quantum correlations can be tested.
description: 6 pages, 4 figures
Measuring the single-particle density matrix for fermions and hard-core bosons in an optical lattice
Creators: name: Ardila, Luis A. Peña
name: Heyl, Markus
name: Eckardt, André
Publisher: name: arXiv
Year: 2018
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Ultracold atoms in optical lattices provide clean, tunable, and well-isolated realizations of paradigmatic quantum lattice models. With the recent advent of quantum-gas microscopes, they now also offer the possibility to measure the occupations of individual lattice sites. What, however, has not yet been achieved is to measure those elements of the single-particle density matrix, which are off-diagonal in the occupation basis. Here, we propose a scheme to access these basic quantities both for fermions as well as hard-core bosons and investigate its accuracy and feasibility. The scheme relies on the engineering of a large effective tunnel coupling between distant lattice sites and a protocol that is based on measuring site occupations after two subsequent quenches.
description: 5 pages, 3 figures
Probing Lyman-alpha Absorbers with Double Lines of Sight
Creators: name: Charlton, Jane C.
name: Churchill, Christopher W.
name: Linder, Suzanne M.
Publisher: name: arXiv
Year: 1995
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Study of Lyman-alpha absorption lines in the spectra of double line of sight (DLOS) quasars holds the promise of diagnosing the nature of the structures that give rise to Lyman-alpha absorption. Based on simulations of DLOS with various separations through a single population of absorbers, four tests have been designed to diagnose absorber mass distributions (smoothly varying with radius or irregular), geometries (spherical or disk/slab--like), and kinematics (isotropic or systematic velocities). Applying the tests to existing data at redshifts around two we find that: (1) The observed neutral hydrogen column density (N(HI)) distributions of Lyman-alpha lines coincident to both LOS are consistent with a smooth mass distribution. (2) Observed large anticoincident N(HI) are not consistent with a single population of smooth spherical absorbers, which should exhibit sharp cut--offs at small N(HI) in the N(HI) distribution. (3) There is marginal evidence that the observed RMS value of velocity differences between coincident lines increases with DLOS separation as is expected for disk/slab--like absorbers that have systematic velocity fields. (4) The observed velocity dispersion along a single LOS is small compared to the RMS difference between widely separated LOS, which is not consistent with models of cloudlets moving isotropically within a spherical structure. Overall, only a smooth disk/slab--like model with systematic velocities remains consistent with the inferred properties of a single population of Lyman-alpha absorbers.
description: 7 pages with figures included, gzipped postscript; also available at http://ucowww.ucsc.edu/~cwc/qso/abstract.html ; Astrophysical Journal Letters (in press)
A general solution to detect anomalies in networked distributed sensing systems
Creators: name: Chen, Po-Yu
Publisher: name: Imperial College London
Year: 2015

description: Networked distributed sensing systems (NDSSs) have been widely adopted in many real-world applications which can be either described as cyber-physical system (CPS) or indeed the Internet of Things (IoT). The security and trust in such systems are of paramount importance. In practice, sensor readings may be abnormal or faulty due to various unpredictable causes such as the harsh environments in which they are deployed, the sensors are inherently fault-prone, or they experience malicious attacks. However, although a large body of research has been looking at detecting such anomalies, we have yet seen a common solution that can eﬀectively detect all general anomalies in NDSSs. Many current solutions are either simple but limited by rigid assumptions, or powerful but complex and therefore not suited to resource scarce and large-scale NDSSs. To overcome this problem, we have investigated the causes and patterns of anomaly behaviours in NDSS, and propose a lightweight general solution that can identify most general anomalies in resource-limited NDSSs. This solution consists of three diﬀerent components: feature extraction, sensor grouping, and anomaly classiﬁcation. In feature extraction, we propose two multi-feature dimensionality reduction algorithms, MFDR and MFDR-N. These algorithms extract distinctive time-series features from raw sensor measurements and provide their dimensionality-reduced (DR) representations. In comparison to traditional time-series approaches, MFDR and MFDR-N can provide multiple types of time-series features which can better approximate the original data with smaller error. In addition, to ensure our solution can scale to diﬀerent sizes of NDSSs while being able to perform sophisticated detection schemes, we propose a distributed matching-based grouping algorithm, DMGA, which clusters sensors into correlation groups where a strong spatiotemporal correlation exists among all sensors. To the best of our knowledge, this grouping algorithm is the ﬁrst one to provide performance guarantees in terms of correlation strength. Ultimately, we propose two general anomaly detection classiﬁers, GAD and FGAD, to capture rapid and gradual pattern changes in sensor measurements, respectively. Both of these are lightweight in terms of computation complexity and can adapt fast to changes in non-stationary environments. Our experimental results show that both GAD and FGAD are very effective against various types of anomalies in real-world NDSS.
Ovis aries subsp. africana Linnaeus, 1758, subspec. nov.
Creators: name: Linnaeus, Carolus
Publisher: name: Laurentius Salvius
Year: 1758
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Mammalia
Artiodactyla
Bovidae
Ovis
Ovis aries
Ovis aries subsp. africana

description: Ovis aries subsp. africana [subspec. nov.]
africana. Raj. 75. pro lana pilis brevibus hirta.
description: Published as part of Linnaeus, Carolus, 1758, Systema Naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, Stockholm :Laurentius Salvius on page 70, DOI: 10.5962/bhl.title.542, http://zenodo.org/record/3922206
A Survey of Near Infrared Emission in Visual Reflection Nebulae
Creators: name: Sellgren, K.
name: Werner, M. W.
name: Allamandola, L. J.
Publisher: name: arXiv
Year: 1995
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present a survey for extended 2.2 $μ$m emission in 20 new visual reflection nebulae, illuminated by stars with temperatures of 3,600 --- 33,000 K. We detect extended 2.2 $μ$m emission in 13 new nebulae, illuminated by stars with temperatures of 6,800 -- 33,000 K. For most of these 13 nebulae we have measured $J-K$, $H-K$, and $K-L'$, as well as obtaining surface brightness measurements at the wavelength of the 3.3 $μ$m emission feature. All of the reflection nebulae with extended near infrared emission in excess over scattered starlight have very similar near infrared colors and show the 3.3 $μ$m feature in emission with similar feature-to-continuum ratios. The 3.3 $μ$m feature-to-continuum ratio ranges from $\sim$3 to $\sim$9, both within individual nebulae and from nebula to nebula, which suggests that the 3.3 $μ$m feature and its underlying continuum arise from different materials, or from different ranges of sizes within a size distribution of particles. No dependence on the temperature of the illuminating star is seen in the near infrared colors or 3.3 $μ$m feature-to-continuum ratio, over a factor of two in stellar temperature. This is similar to our previous IRAS results, in which we found no dependence of the ratio of 12 $μ$m to 100 $μ$m surface brightnesses in reflection nebulae illuminated by stars with temperatures of 5,000--33,000 K.
description: 38 pages (87 kB), AASTex format. Also 7 Postscript figures (80 kB), tarred, compressed and uuencoded, added with 'figure' command. Postscript file or hardcopy available upon request to sellgren@payne.mps.ohio-state.edu. ** Sep. 13, 1995: revised Fig. 1. Compressed postscript text+figs now available at ftp://bessel.mps.ohio-state.edu/pub/sellgren/survey.ps.Z ** Accepted, ApJS (Feb. 1996)
The Variable Stars and Blue Horizontal Branch of the Metal-Rich Globular Cluster NGC 6441
Creators: name: Layden, A. C.
name: Ritter, L. A.
name: Welch, D. L.
name: Webb, T. M. A.
Publisher: name: arXiv
Year: 1998
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present time-series VI photometry of the metal-rich ([Fe/H] = -0.53) globular cluster NGC 6441. Our color-magnitude diagram shows that the extended blue horizontal branch seen in Hubble Space Telescope data exists in the outermost reaches of the cluster. The red clump slopes nearly parallel to the reddening vector. A component of this slope is due to differential reddening, but part is intrinsic. The blue horizontal branch stars are more centrally concentrated than the red clump stars. We have discovered about 50 new variable stars near NGC 6441, among them eight or more RR Lyrae stars which are very probably cluster members. Comprehensive period searches over the range 0.2-1.0 days yielded unusually long periods (0.5-0.9 days) for the fundamental pulsators compared with field RR Lyrae of the same metallicity. Three similar long-period RR Lyrae are known in other metal-rich globulars. With over ten examples in hand, it seems that a distinct sub-class of RR Lyrae is emerging. The observed properties of the horizontal branch stars are in reasonable agreement with recent models which invoke deep mixing to enhance the atmospheric helium abundance, while they conflict with models which assume high initial helium abundance. The light curves of the c-type RR Lyrae seem to have unusually long rise times and sharp minima. Reproducing these light curves in stellar pulsation models may provide another means of constraining the physical variables responsible for the anomalous blue horizontal branch extension and sloped red clump observed in NGC 6441.
description: 30 pages plus 6 EPS and 6 JPEG figures; uses AAS TeX. Accepted by the Astronomical Journal. Minor changes include computing He abundance, modifications to Figs 1 and 8, and expansion on idea that blue HB stars may be produced in binaries
A Brief Overview of Bipartite and Multipartite Entanglement Measures
Creators: name: Haddadi, Saeed
name: Bohloul, Mohammad
Publisher: name: arXiv
Year: 2018
Subjects: subject: Quantum Physics (quant-ph)
subject: Applied Physics (physics.app-ph)
subject: FOS: Physical sciences
subject: 81P40

description: Measuring entanglement is a demanding task in the field of quantum computation and quantum information theory. Recently, some authors experimentally demonstrated an embedding quantum simulator, using it to efficiently measure two-qubit entanglement. Here, we are reviewing some measures of entanglement which are used for pure and mixed states. Furthermore, we have reported the efficient bipartite and multipartite entanglement measures.
description: 6 pages, Efficient entanglement measures, Int J Theor Phys (2018)
Towards Sustainable Maritime Transportation in the Galapagos Islands with green hydrogen
Creators: name: Ramos, Emilia
Publisher: name: Zenodo
Year: 2024
Subjects: Hydrogen
MARIO
Galapagos Islands
Maritime Transportation
Input-Output

description: This proposal assesses the feasibility of transitioning from fossil fuels to green hydrogen as the primary energy source to propel maritime transport in the Galapagos Islands. It incorporates an inclusive approach that considers the environmental impact of the system. The project aims to formulate a study with the goal of facilitating an understanding of the potential regional consequences associated with transitioning to this alternative and facilitating the formulation of a transition plan. This is achieved by mitigating economic and environmental barriers that may arise with the introduction of this new technology. This transition is presented as a significant step towards decarbonizing the islands' energy system.
Many-body localization in Fock-space: a local perspective
Creators: name: Logan, David E.
name: Welsh, Staszek
Publisher: name: arXiv
Year: 2018
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: FOS: Physical sciences

description: A canonical model for many-body localization (MBL) is studied, of interacting spinless fermions on a lattice with uncorrelated quenched site-disorder. The model maps onto a tight-binding model on a `Fock-space (FS) lattice' of many-body states, with an extensive local connectivity. We seek to understand some aspects of MBL from this perspective, via local propagators for the FS lattice and their self-energies (SE's); focusing on the SE probability distributions, over disorder and FS sites. A probabilistic mean-field theory (MFT) is first developed, centered on self-consistent determination of the geometric mean of the distribution. Despite its simplicity this captures some key features of the problem, including recovery of an MBL transition, and predictions for the forms of the SE distributions. The problem is then studied numerically in $1d$ by exact diagonalization, free from MFT assumptions. The geometric mean indeed appears to act as a suitable order parameter for the transition. Throughout the MBL phase the appropriate SE distribution is confirmed to have a universal form, with long-tailed Lévy behavior as predicted by MFT. In the delocalized phase for weak disorder, SE distributions are clearly log-normal; while on approaching the transition they acquire an intermediate Lévy-tail regime, indicative of the incipient MBL phase.
description: 18 pages, 14 figures Phys Rev B in press
Active dumbbells: dynamics and morphology in the coexisting region
Creators: name: Petrelli, Isabella
name: Digregorio, Pasquale
name: Cugliandolo, Leticia F.
name: Gonnella, Giuseppe
name: Suma, Antonio
Publisher: name: arXiv
Year: 2018
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: With the help of molecular dynamics simulations we study an ensemble of active dumbbells in purely repulsive interaction. We derive the phase diagram in the density-activity plane and we characterise the various phases with liquid, hexatic and solid character. The analysis of the structural and dynamical properties, such as enstrophy, mean square displacement, polarisation, and correlation functions, shows the continuous character of liquid and hexatic phases in the coexisting region when the activity is increased starting from the passive limit.
Nonlinear modelling of masonry infill walls in building structures subject to extreme loading
Creators: name: Khojasteh, Amirabbas
Publisher: name: Imperial College London
Year: 2017

description: Abstract The motivation of this research is driven by the need for an efficient and accurate nonlinear modelling method for the analysis of unreinforced masonry infill walls, particularly their influence on the behaviour of frame buildings. In this modelling approach the nonlinear behaviour of masonry material is simulated by an anisotropic material model, and the detachment between masonry walls and surrounding frames, leading to a boundary condition nonlinearity, is taken into account. In addition, the geometric nonlinearity caused by out-of-plane loadings is considered. Two strategies for modelling the infill walls are studied, and their benefits and drawbacks in different applications were reviewed. The microscale modelling dealing with simulating the constituents of masonry individually, e.g. units and mortar, at two detailed and simplified levels, are discussed and the latter is then utilised for the verification of the models presented in this research. The macroscale modelling, considering the masonry wall as a smeared crack continuum, is then elaborated and an anisotropic material model, previously presented for plane stress condition, is adapted for a plate bending application. This nonlinear material model utilises two different failure criteria in tensile and compressive regimes, and determines stresses and strains in a plastic range using a return mapping algorithm. A novel interface element is formulated to reproduce the more realistic behaviour of infilled frames by taking into account the nonlinearity caused by variation of boundary conditions. This element simulates the separation between infill walls and surrounding frame, while a newly defined co-rotational local reference system facilitates the treatment of geometric nonlinearity. The interface element is coupled with a previously developed constitutive material model to be able to deal with material nonlinearity. The new features of this element, including rotational DOFs in nodes, also enable it to accompany shell elements for plate bending problems with large displacements. These characteristics create an effective modelling method for in-plane and out-of-plane loads. The proposed method is finally employed in a model of infill frame to demonstrate the accuracy of the method in predicting various failure mechanisms in infill walls.