cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Tracing mixing in stars: new beryllium observations of the open clusters NGC 2516, Hyades, and M67
Creators: name: Randich, S.
name: Primas, F.
name: Pasquini, L.
name: Sestito, P.
name: Pallavicini, R.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Determinations of beryllium abundance in stars, together with lithium, provide a key tool to investigate the so far poorly understood extra-mixing processes at work in stellar interiors. We measured Be in three open clusters,complementing existing Be surveys, and aiming at gathering a more complete empirical scenario of the evolution of Be as a function of stellar age and temperature. Specifically, we analyzed VLT/UVES spectra of members of NGC 2516, the Hyades, and M 67 to determine their Be and Li abundances. In the first two clusters we focused on stars cooler than 5400 K, while the M 67 sample includes stars warmer than 6150 K, as well as two subgiants and two blue stragglers. We also computed the evolution of Be for a 0.9 Mo star based on standard evolutionary models. We find different emprical behaviours for stars in different temperature bins and ages. Stars warmer than 6150 K show Be depletion and follow a Be vs. Li correlation while Be is undepleted in stars in the ~6150-5600 K range. NGC 2516 members cooler than 5400 K have not depleted any Be, but older Hyades of similar temperature do show some depletion. Be is severely depleted in the subgiants and blue stragglers. The results for warm stars are in agreement with previous studies, supporting the hypothesis that mixing in this temperature regime is driven by rotation. The same holds for the two subgiants that have evolved from the "Li gap". This mechanism is instead not the dominant one for solar-type stars. We show that Be depletion of cool Hyades cannot simply be explained by the effect of increasing depth of the convective zone. Finally, the different Be content of the two blue stragglers suggests that they have formed by two different processes (i.e., collisions vs. binary merging).
description: 19 pages, 10 figures, accepted for publication in Astronomy & Astrophysics
A Scanning 2-Grating Free Electron Mach-Zehnder Interferometer
Creators: name: Johnson, Cameron W.
name: Turner, Amy E.
name: McMorran, Benjamin J.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Instrumentation and Detectors (physics.ins-det)
subject: Optics (physics.optics)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We demonstrate a 2-grating free electron Mach-Zehnder interferometer constructed in a transmission electron microscope. A symmetric binary phase grating and condenser lens system forms two spatially separated, focused probes at the sample which can be scanned while maintaining alignment. The two paths interfere at a second grating, creating in constructive or destructive interference in output beams. This interferometer has many notable features: positionable probe beams, large path separations relative to beam width, continuously tunable relative phase between paths, and real-time phase information. Here we use the electron interferometer to measure the relative phase shifts imparted to the electron probes by electrostatic potentials as well as a demonstration of quantitative nanoscale phase imaging of a polystyrene latex nanoparticle.
description: 9 pages, 5 figures
Approximate two-body generating Hamiltonian for the PH-Pfaffian wavefunction
Creators: name: Pakrouski, Kiryl
Publisher: name: arXiv
Year: 2021
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We present two 2-body Hamiltonians that approximate the exact PH-Pfaffian wavefunction with their ground states for all the system sizes where this wavefunction has been numerically constructed to date. The approximate wavefunctions have high overlap with the original and reproduce well the low-lying entanglement spectrum and structure factor. The approximate generating Hamiltonians are obtained by an optimisation procedure where three to four pseudopotentials are varied in the neighbourhood of second Landau level Coulomb interaction or of a non-interacting model. They belong to a finite region in the variational space of Hamiltonians where each point approximately generates the PH-Pfaffian. We diagonalize the identified Hamiltonians for up to 20 electrons and find that for them the PH-Pfaffian shift appears energetically more favorable. Possibility to interpret the data in terms of composite fermions is discussed.
description: v3: journal version. Added various definitions to make the paper self-contained. Improved presentation incl. clearer plots
An infrared-submillimeter study of star-forming regions selected by the ISOSS 170um survey
Creators: name: Hennemann, M.
name: Birkmann, S. M.
name: Krause, O.
name: Lemke, D.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Using the ISOPHOT Serendipity Survey (ISOSS) at 170um a sample of galactic star-forming regions exhibiting very cold dust temperatures (< 20 K) and high masses (> 100 M_sun) has been established. We characterise the star-forming content of five regions that were selected as potential sites for early stage high-mass star formation using SCUBA (JCMT) and Spitzer observations. In every region we identify one to four submillimeter clumps with projected sizes between 0.1 and 0.4 pc. The dust temperatures range from 11.6 to 21.3 K and the estimated clump masses are 2 to 166 M_sun. Towards the majority of submillimeter peaks we find point sources in the near- to mid-infrared. Most are interpreted as low-mass young stellar objects but we also detect very red sources. They probably represent very young and deeply embedded protostars that continue to accrete clump material and may reach higher masses. Several candidate intermediate-mass proto- or pre-main-sequence stars embedded in the clumps are identified. A subset of four clumps may be massive enough (> 100 M_sun) to form high-mass stars and accompanying clusters. The absence of stellar precursors with current masses in the high-mass regime leave the type of star formation occuring in the clumps unsettled. We confirm the presence of large fractions of cold material as derived from large-scale far-infrared measurements which dominates the emission of most clumps and suggests that the star-forming process will continue.
description: 11 pages, 11 figures, accepted for publication in A&A
MOESM1 of Biosynthesis and Antibacterial Activity of Silver Nanoparticles Using Yeast Extract as Reducing and Capping Agents
Creators: name: Shu, Mengjun
name: He, Fengjiao
name: Li, Zhaohui
name: Zhu, Xingzhong
name: Ma, Yujie
name: Zhou, Zhihua
name: Yang, Zhi
name: Gao, Feng
name: Zeng, Min
Publisher: name: figshare
Year: 2020
Subjects: Biochemistry
Space Science
Medicine
Cell Biology
Molecular Biology
Pharmacology
Biological Sciences not elsewhere classified
Information Systems not elsewhere classified
Developmental Biology
Cancer

description: Additional file 1: Figure S1 Zeta potential of Ag NPs versus pH value. Table S1 Summary of of biomolecules in yeast extract.
A fast method for Stokes profile synthesis -- Radiative transfer modeling for ZDI and Stokes profile inversion
Creators: name: Carroll, T. A.
name: Kopf, M.
name: Strassmeier, K. G.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: The major challenges for a fully polarized radiative transfer driven approach to Zeeman-Doppler imaging are still the enormous computational requirements. In every cycle of the iterative interplay between the forward process (spectral synthesis) and the inverse process (derivative based optimization) the Stokes profile synthesis requires several thousand evaluations of the polarized radiative transfer equation for a given stellar surface model. To cope with these computational demands and to allow for the incorporation of a full Stokes profile synthesis into Doppler- and Zeeman-Doppler imaging applications as well as into large scale solar Stokes profile inversions, we present a novel fast and accurate synthesis method for calculating local Stokes profiles. Our approach is based on artificial neural network models, which we use to approximate the complex non-linear mapping between the most important atmospheric parameters and the corresponding Stokes profiles. A number of specialized artificial neural networks, are used to model the functional relation between the model atmosphere, magnetic field strength, field inclination, and field azimuth, on one hand and the individual components (I,Q,U,V) of the Stokes profiles, on the other hand. We performed an extensive statistical evaluation and show that our new approach yields accurate local as well as disk-integrated Stokes profiles over a wide range of atmospheric conditions. The mean rms errors for the Stokes I and V profiles are well below 0.2% compared to the exact numerical solution. Errors for Stokes Q and U are in the range of 1%. Our approach does not only offer an accurate approximation to the LTE polarized radiative transfer it, moreover, accelerates the synthesis by a factor of more than 1000.
description: A&A, in press
Pressure-driven Nitrogen Flow in Divergent Microchannels with Isothermal Walls
Creators: name: Ebrahimi, Amin
name: Shahabi, Vahid
name: Roohi, Ehsan
Publisher: name: arXiv
Year: 2021
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: Gas flow and heat transfer in confined geometries at micro and nano scales differ considerably from those at macro-scales, mainly due to nonequilibrium effects such as velocity slip and temperature jump. The nonequilibrium effects enhance with a decrease in the characteristic length-scale of the fluid flow or the gas density, leading to the failure of the standard Navier-Stokes-Fourier (NSF) equations in predicting thermal and fluid flow fields. The direct simulation Monte-Carlo (DSMC) method is employed in the present work to investigate pressure-driven nitrogen flow in divergent microchannels with various divergence angles and isothermal walls. The thermal fields obtained from numerical simulations are analysed for different inlet-to-outlet pressure ratios (1.5 $\leq Π\leq$ 2.5), tangential momentum accommodation coefficients and Knudsen numbers (0.05 $\leq \mathrm{Kn} \leq$ 12.5), covering slip to free-molecular rarefaction regimes. The thermal field in the microchannel is predicted, heat-lines are visualised, and the physics of heat transfer in the microchannel is discussed. Due to the rarefaction effects, the direction of heat flow is largely opposite to that of the mass flow. However, the interplay between thermal and pressure gradients, which are affected by geometrical configurations of the microchannel and applied boundary conditions, determines the net heat flow direction. Additionally, the occurrence of thermal separation and cold-to-hot heat transfer (also known as anti-Fourier heat transfer) in divergent microchannels is explained.
description: 18 pages, 11 figures
Photogalvanic effects in HgTe quantum wells
Creators: name: Wittmann, B.
name: Ravash, R.
name: Diehl, H.
name: Danilov, S. N.
name: Kvon, Z. D.
name: Tarasenko, S. A.
name: Ivchenko, E. L.
name: Mikhailov, N. N.
name: Dvoretsky, S. A.
name: Prettl, W.
name: Ganichev, S. D.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We report on the observation of the terahertz radiation induced circular (CPGE) and linear (LPGE) photogalvanic effects in HgTe quantum wells. The current response is well described by the phenomenological theory of CPGE and LPGE.
description: 2 pages, 2 figures
Non-existence of measurable solutions of certain functional equations via probabilistic approaches
Creators: name: Okamura, Kazuki
Publisher: name: arXiv
Year: 2021
Subjects: subject: Classical Analysis and ODEs (math.CA)
subject: Probability (math.PR)
subject: FOS: Mathematics
subject: 39B22, 62E10

description: This paper deals with functional equations in the form of $f(x) + g(y) = h(x,y)$ where $h$ is given and $f$ and $g$ are unknown. We will show that if $h$ is a Borel measurable function associated with characterizations of the uniform or Cauchy distributions, then there is no measurable solutions of the equation. Our proof uses a characterization of the Dirac measure and it is also applicable to the arctan equation.
description: 7 pages, to appear in Aequationes mathematicae
Boundary Conformal Field Theory and Ribbon Graphs: a tool for open/closed string dualities
Creators: name: Carfora, Mauro
name: Dappiaggi, Claudio
name: Gili, Valeria L.
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We construct and fully characterize a scalar boundary conformal field theory on a triangulated Riemann surface. The results are analyzed from a string theory perspective as tools to deal with open/closed string dualities.
description: 40 pages, 7 figures; typos corrected
"La sagesse de Palamède : les dés, les pions et l'établissement d'un ordre (à propos de Philostrate, Sur les héros, 10 Follet)", in D. Bouvier and V. Dasen (eds), Héraclite : Le temps est un enfant qui joue, Collection Jeu/ Play/Spiel 1, Liège, Presses Universitaires de Liège, 2020, p. 75-94.
Creators: name: Vespa, Marco
Publisher: name: Zenodo
Year: 2020

description: “Trictrac”, “checkers”, “chess”, so many misleading translations given over
 time for the Greek word πεσσεία which was actually a form of playful activity practiced with pawns on a board and whose origins extend back to the Trojan War according to traditional stories of ancient Greece.
 Far from being limited to a question of lexicon and choice of translation, this
 article aims to understand the specificities of such a form of game from the analysis of the circumstances of its invention and the identity of its author, namely the hero Palamedes. By a detailed analysis of the passages concerning Palamedes and his invention of games, from Gorgias to Philostratus, this contribution is intended to allow a better understanding of how far the πεσσεία was linked to a very particular modality of the divine action of Palamedes, namely his prophetic and mantic power that made him a hero of the semiotic structuring of space.
Energy and Cost Efficient Resource Allocation for Blockchain-Enabled NFV
Creators: name: Taskou, Shiva Kazemi
name: Rasti, Mehdi
name: Nardelli, Pedro H. J.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Networking and Internet Architecture (cs.NI)
subject: Systems and Control (eess.SY)
subject: FOS: Computer and information sciences
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: Network function virtualization (NFV) is a promising technology to make 5G networks flexible and agile. NFV decreases operators' OPEX and CAPEX by decoupling the physical hardware from the functions they perform. In NFV, users' service request can be viewed as a service function chain (SFC) consisting of several virtual network functions (VNFs) which are connected through virtual links. Resource allocation in NFV is done through a centralized authority called NFV Orchestrator (NFVO). This centralized authority suffers from some drawbacks such as single point of failure and security. Blockchain (BC) technology is able to address these problems by decentralizing resource allocation. The drawbacks of NFVO in NFV architecture and the exceptional BC characteristics to address these problems motivate us to focus on NFV resource allocation to users' SFCs without the need for an NFVO based on BC technology. To this end, we assume there are two types of users: users who send SFC requests (SFC requesting users) and users who perform mining process (miner users). For SFC requesting users, we formulate NFV resource allocation (NFV-RA) problem as a multi-objective problem to minimize the energy consumption and utilized resource cost, simultaneously.
The Integrated Density of States of the 1D Discrete Anderson-Bernoulli Model at Rational Energies
Creators: name: Sánchez-Mendoza, Daniel
Publisher: name: arXiv
Year: 2021
Subjects: subject: Mathematical Physics (math-ph)
subject: Spectral Theory (math.SP)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: We show there is a countable dense set of energies at which the integrated density of states of the 1D discrete Anderson-Bernoulli model can be given explicitly and does not depend on the disorder parameter, provided the latter is above an energy-dependent threshold.
description: 10 Pages, 3 Figures. v2: Final version, to appear in JMP
Expected maximum of bridge random walks & Lévy flights
Creators: name: De Bruyne, Benjamin
name: Majumdar, Satya N.
name: Schehr, Gregory
Publisher: name: arXiv
Year: 2021
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Mathematical Physics (math-ph)
subject: Probability (math.PR)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: We consider one-dimensional discrete-time random walks (RWs) with arbitrary symmetric and continuous jump distributions $f(η)$, including the case of Lévy flights. We study the expected maximum ${\mathbb E}[M_n]$ of bridge RWs, i.e., RWs starting and ending at the origin after $n$ steps. We obtain an exact analytical expression for ${\mathbb E}[M_n]$ valid for any $n$ and jump distribution $f(η)$, which we then analyze in the large $n$ limit up to second leading order term. For jump distributions whose Fourier transform behaves, for small $k$, as $\hat f(k) \sim 1 - |a\, k|^μ$ with a Lévy index $00$, we find that, at leading order for large $n$, ${\mathbb E}[M_n]\sim a\, h_1(μ)\, n^{1/μ}$. We obtain an explicit expression for the amplitude $h_1(μ)$ and find that it carries the signature of the bridge condition, being different from its counterpart for the free random walk. For $μ=2$, we find that the second leading order term is a constant, which, quite remarkably, is the same as its counterpart for the free RW. For generic $0< μ< 2$, this second leading order term is a growing function of $n$, which depends non-trivially on further details of $\hat f (k)$, beyond the Lévy index $μ$. Finally, we apply our results to compute the mean perimeter of the convex hull of the $2d$ Rouse polymer chain and of the $2d$ run-and-tumble particle, as well as to the computation of the survival probability in a bridge version of the well-known "lamb-lion" capture problem.
description: 31 pages, 6 figures
Propagation Measurements and Path Loss Models for sub-THz in Urban Microcells
Creators: name: Xing, Yunchou
name: Rappaport, Theodore S.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Information Theory (cs.IT)
subject: FOS: Computer and information sciences

description: Terahertz frequency bands will likely be used for the next-generation wireless communication systems to provide data rates of hundreds of Gbps or even Tbps because of the wide swaths of unused and unexplored spectrum. This paper presents two outdoor wideband measurement campaigns in downtown Brooklyn (urban microcell environment) in the sub-THz band of 140 GHz with TX-RX separation distance up to 100 m: i) terrestrial urban microcell measurement campaign, and ii) rooftop surrogate satellite and backhaul measurement campaign. Outdoor omnidirectional and directional path loss models for both line-of-sight and non-line-of-sight scenarios, as well as foliage loss (signal attenuation through foliage), are provided at 140 GHz for urban microcell environments. These measurements and models provide an understanding of both the outdoor terrestrial (e.g., 6G cellular and backhaul) and non-terrestrial (e.g., satellite and unmanned aerial vehicle communications) wireless channels, and prove the feasibility of using THz frequency bands for outdoor fixed and mobile cellular communications. This paper can be used for future outdoor wireless system design at frequencies above 100 GHz.
A modification of Oersted experiment
Creators: name: Stoyanov, Dimitar G
Publisher: name: arXiv
Year: 2008
Subjects: subject: General Physics (physics.gen-ph)
subject: Classical Physics (physics.class-ph)
subject: FOS: Physical sciences

description: The paper describes a simple setup of Oersted experiment. A planar coil of wires has been used to deflect vigorously the magnetic needle (more than 80 angular degrees) when a current of up to 1 A flows along it. Based on theoretical analysis the torque on the magnetic field is analytically expressed taking into account the inhomogeneity of the field and the needle shape. What is more, a procedure to measure the Earth's magnetic component is implied and implemented and its magnitude has been estimated following the same steps.
description: 11 pages, 7 figures
Future Directions of Research in Geometry: A Summary of the Panel Discussion at the 2007 Midwest Geometry Conference
Creators: name: Peterson, Lawrence J.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Differential Geometry (math.DG)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences

description: The 2007 Midwest Geometry Conference included a panel discussion devoted to open problems and the general direction of future research in fields related to the main themes of the conference. This paper summarizes the comments made during the panel discussion.
description: This is a contribution to the Proceedings of the 2007 Midwest Geometry Conference in honor of Thomas P. Branson, published in SIGMA (Symmetry, Integrability and Geometry: Methods and Applications) at http://www.emis.de/journals/SIGMA/
Extremal Presentations for Classical Lie Algebras
Creators: name: panhuis, Jos in 't
name: Postma, Erik
name: Roozemond, Dan
Publisher: name: arXiv
Year: 2007
Subjects: subject: Rings and Algebras (math.RA)
subject: FOS: Mathematics
subject: 17B20, 17B50

description: The long-root elements in Lie algebras of Chevalley type have been well studied and can be characterized as extremal elements, that is, elements $x$ such that the image of $(\ad x)^2$ lies in the subspace spanned by $x$. In this paper, assuming an algebraically closed base field of characteristic not 2, we find presentations of the Lie algebras of classical Chevalley type by means of minimal sets of extremal generators. The relations are described by simple graphs on the sets. For example, for $C_n$ the graph is a path of length $2n$, and for $A_n$ the graph is the triangle connected to a path of length $n-3$.
description: 26 pages, 6 figures
Development of the Episodic Memory Network in Early Childhood: Insights from Graph Theoretical Analysis
Creators: name: Botdorf, Morgan Anna
Publisher: name: Digital Repository at the University of Maryland
Year: 2019
Subjects: subject: Neurosciences
subject: FOS: Clinical medicine
subject: Developmental psychology
subject: Cognitive psychology
subject: Development
subject: Episodic Memory
subject: Functional Connectivity
subject: Functional MRI
subject: Network Analysis

description: The hippocampal memory network has been identified in both children and adults and shown to be related to episodic memory ability. However, it remains unclear how its organization may differ across development, particularly during periods of large behavioral gains in memory ability. The goal of the present study was to utilize graph theoretical analysis to investigate the integration of the hippocampus within the memory network and segregation from other networks (i.e., fronto-parietal and cingulo-opercular attention networks) in the brain. Results indicated that with age, there was a general increase in connections between the hippocampus and both regions within the memory network and regions in other networks in the brain. These differences may contribute to improvements in memory typically observed in early childhood. Future analyses will examine relations with memory behavior and probe whether segregation is observed using other metrics, a sample of adult data, or other networks (e.g., sensorimotor).
Illuminating Happiness: Developing a Therapeutic Cohousing Community for Those Affected by SAD
Creators: name: Conover, Sara Elizabeth
Publisher: name: Digital Repository at the University of Maryland
Year: 2019
Subjects: subject: Architecture
subject: FOS: Civil engineering

description: Seasonal Affective Disorder is currently estimated to affect 10 million Americans, meaning that roughly 1 in 30 people struggle with SAD (Yellow Brick Program). This thesis explores the question: how can architectural design improve the mental and physical health of those suffering with SAD? By establishing a cohousing community for those affected, levels of social interaction can increase and in turn provide additional social and psychological benefits. In order to develop a positive and engaging living space, this thesis proposes several architectural design principles for well-being that can then be applied to this type of community. These principles are derived from environmental psychology, indoor environmental qualities, healing architecture, and Nordic winter living cultures in addition to characteristics of cohousing. The final approach will result in a cohousing community implemented in a case study in the Northeastern United States, an area where SAD is most common. These methods can then inform architects on how to develop stimulating and engaging places for those who suffer with depression in order to inspire a positive outlook on the colder seasons.
Can we understand the decay width of the $T_{cc}^+$ state?
Creators: name: Ling, Xi-Zhe
name: Liu, Ming-Zhu
name: Geng, Li-Sheng
name: Wang, En
name: Xie, Ju-Jun
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Inspired by the recent discovery of a doubly charmed tetraquark state $T_{cc}^+$ by the LHCb Collaboration, we employ the effective Lagrangian approach to investigate the decay width of $T_{cc}^{+}\to D^{+} D^{0}π^{0}/D^{0} D^{0}π^{+}$ and $T_{cc}^{+}\to D^{0}D^{+}γ$ with the assumption that $T_{cc}^{+}$ is an isoscalar $DD^{\ast}$ molecule. We show that both the $T_{cc}\to D Dπ$ and $T_{cc}\to DDγ$ modes contribute to the decay width of $T_{cc}$, with the former being dominant. The resulting total decay width of about $Γ=63$ keV is smaller than the experimental decay width obtained from the Breit-Wigner fit of the LHCb data, $Γ=410\pm 165\pm 43^{+18}_{-38}$ keV, while close to the number obtained from the alternative unitary analysis, $Γ=48\pm 2^{+0}_{-14}$ keV, which supports the molecular nature of $T_{cc}$.
Novel secondary metabolites from selected cold water marine invertebrates
Creators: name: Williams, David Ellis
Publisher: name: University of British Columbia
Year: 2010

description: A study of the secondary metabolism of two nudibranchs and one soft coral has led to the isolation of eighteen new and two known secondary metabolites. The structures of all compounds were determined by a combination of the interpretation of spectral data, chemical degradations and interconversions, and single crystal x-ray diffraction analysis. The British Columbian dorid nudibranch Diaulula sandiegensis yielded two new steroidal metabolites, diaulusterols A (41) and B (42). The 25-(3-hydroxybutanoate) residue of diaulusterol A (41) and the 2α,3α-diol array of both 41 and 42 are not commonly encountered in naturally occurring steroids. Both metabolites exhibited considerable antibacterial and antifungal activity. Steroid 41 exhibited fish antifeedant activity. The relative concentration of 4.1 and 42 in the skin extracts of D. sandiegensis appears to be related to the animals' seasonal abundance. Extracts of the British Columbian soft coral Gersemia rubiformis yielded a series of ten diterpenes possessing cembrane (170-175), pseudopterane (167-169) and gersolane (176) carbon skeletons. The structure of an eleventh diterpene remains unresolved. In addition, the structure of a degraded diterpene possessing a 13-membered ring (177) is tentatively proposed. G. rubiformis represents the first example of a soft coral to yield pseudopterane diterpenes. The organism is the first to contain cembrane, pseudopterane and gersolane metabolites, a fact which has biogenetic implications. Two new sesquiterpenes were also isolated. Tochuinyl acetate (165) and dihydrotochuinyl acetate (166) represent the first examples of cuparane sesquiterpenes to be isolated from a soft coral. A biogenesis is proposed. Metabolite 166 exhibited fish antifeedant activity. Investigations of Gersemia rubiformis collected in Newfoundland waters revealed that the secondary metabolism differed from west coast specimens. The isolation of the new unstable sesquiterpene (+)-β-cubebene-3-acetate (178) resulted. Skin extracts of the dendronotoid nudibranch Toquina tetraquetra were examined in an attempt to correlate its feeding dependency and lack of predation to the presence of allomones. Metabolites 165, 166, 170, 179 and the new butanoate diterpene 180 could be traced to the coelenterates which make up the animal's diet. Tochuinyl acetate (165), dihydrotochuinyl acetate (166) and rubifolide (170) were previously found in extracts of Gersemia rubiformis. Ptilosarcenone (179) has been reported as one of the major metabolites of the sea pen Ptilosarcus gurneyi²¹³. The exact origin of a sixth metabolite, pukalide (63), remains unknown. It is proposed that Tochuina tetraquetra selectively sequesters dietary metabolites for defensive purposes.
Gamma Rays frim the Galactic Centre
Creators: name: Erlykin, A. D.
name: Wolfendale, A. W.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Recent results from the HESS gamma ray telescope have shown the presence of both a diffuse, extended, flux of gamma rays above ~0.4 TeV and discrete sources in and near the Galactic Centre. Here, we put forward a possible explanation in terms of the diffusion of cosmic ray protons from a succession of supernova remnants (SNR) in the SgrA* region of the Galaxy plus a contribution from SNR in the rest of the Galactic Centre Region, to be called the Galactic Centre Ridge (GCR). Protons are favoured over electrons because the mG magnetic fields in the Region will attenuate energetic electrons severely. Prominent features are the need for 'anomalous diffusion' of the protons in the whole region and the adoption of low efficiency for SNR acceleration in the high density regions. The latter is related by us to the well-known low 'cosmic ray gradient' in the Galaxy. A corroborating feature is the close correlation of inferred cosmic ray intensity with the smoothed intensity of 5 GHZ radio radiation. We attribute this to the presence of the SNR in the GCR.
description: 21 pages, 7 figures, accepted by J. Phys. G: Nucl. Part. Phys
The multi-channel potentiostat: Development and Evaluation of a Scalable Mini-Potentiostat array for investigating electrochemical reaction mechanisms
Creators: name: Pansodtee, Pattawong
name: Selberg, John
name: Jia, Manping
name: Jafari, Mohammad
name: Dechiraju, Harika
name: Thomsen, Thomas
name: Gomez, Marcella
name: Rolandi, Marco
name: Teodorescu, Mircea
Publisher: name: arXiv
Year: 2021
Subjects: subject: Signal Processing (eess.SP)
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: A potentiostat is an essential piece of analytical equipment for studying electrochemical devices and reactions. As the design of electrochemical devices evolve applications for systems with multiple working electrodes have become more common. These applications drive a need for low-cost multi-channel potentiostat systems. We have developed a portable low-cost scalable system with a modular design that can support 8 to 64 channels at a cost as low as \$8 per channel. This design can replace the functionality of commercial potentiostats which cost upwards of \$10k for certain applications. Each channel in the multi-channel potentiostat has an independent adjustable voltage source with a built-in ammeter and switch, making the device flexible for various configurations. The multi-channel potentiostat is designed for low current applications (nA range), but its purpose can change by varying its shunt resistor value. The system can either function as a standalone device or remotely controlled. We demonstrate the functionality of this system for the control of a 24-channel bioelectronic ion pump for open- and closed- loop control of pH.
description: 16 pages, 7 figures
Control of laser wake field acceleration by plasma density profile
Creators: name: Pukhov, A.
name: Kostyukov, I.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Plasma Physics (physics.plasm-ph)
subject: Accelerator Physics (physics.acc-ph)
subject: FOS: Physical sciences

description: We show that both the maximum energy gain and the accelerated beam quality can be efficiently controlled by the plasma density profile. Choosing a proper density gradient one can uplift the dephasing limitation. When a periodic wake field is exploited, the phase synchronism between the bunch of relativistic particles and the plasma wave can be maintained over extended distances due to the plasma density gradient. Putting electrons into the $n-$th wake period behind the driving laser pulse, the maximum energy gain is increased by the factor $2πn$ over that in the case of uniform plasma. The acceleration is limited then by laser depletion rather than by dephasing. Further, we show that the natural energy spread of the particle bunch acquired at the acceleration stage can be effectively removed by a matched deceleration stage, where a larger plasma density is used.
Chemical functionalization of graphene with defects
Creators: name: Boukhvalov, D. W.
name: Katsnelson, M. I.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Defects change essentially not only electronic but also chemical properties of graphene being centers of its chemical activity. Their functionalization is a way to modify electronic and crystal structure of graphene which may be important for graphene-based nanoelectronics. Using hydrogen as an example, we have simulated a chemistry of imperfect graphene for a broad class of defects (Stone-Wales defects, bivacancy, nitrogen substitution impurity, and zigzag edges) by density functional calculations. We have studied also an effect of finite width of graphene nanoribbons on their chemical properties. It is shown that magnetism at graphene edges is fragile with respect to oxidation and, therefore, a chemical protection of the graphene edges may be required for application of graphene in spintronics. At the same time, hydrogenation of the Stone-Wales defects may be a perspective way to create magnetic carbon.
description: 15 pages, 10 figures, discussion about magnetism and several references added
Disorder-driven phase transitions in bosonic fractional quantum Hall liquids
Creators: name: Han, Chao
name: Liu, Zhao
Publisher: name: arXiv
Year: 2021
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We investigate the disorder-driven phase transitions in bosonic fractional quantum Hall liquids at filling factors $f=1/2$ and $f=1$ in the lowest Landau level. We use the evolution of ground-state entanglement entropy, fidelity susceptibility, and Hall conductance with increasing disorder strength to identify the underlying phase transitions. The critical disorder strengths obtained from these different quantities are consistent with each other, validating the reliability of our numerical calculations based on exact diagonalization. At $f=1/2$, we observe a clear transition from the bosonic Laughlin state to a trivial insulating phase. At $f=1$, we identify a direct phase transition from the non-Abelian bosonic Moore-Read state to a trivial insulating phase, although some signs of a disorder-induced intermediate fractional quantum Hall phase were recently reported for the $f=5/2$ fermionic cousin.
description: 11 pages, 8 figures
Improved position measurement of nano electromechanical systems using cross correlations
Creators: name: Doiron, C. B.
name: Trauzettel, B.
name: Bruder, C.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We consider position measurements using the cross-correlated output of two tunnel junction position detectors. Using a fully quantum treatment, we calculate the equation of motion for the density matrix of the coupled detector-detector-mechanical oscillator system. After discussing the presence of a bound on the peak-to-background ratio in a position measurement using a single detector, we show how one can use detector cross correlations to overcome this bound. We analyze two different possible experimental realizations of the cross correlation measurement and show that in both cases the maximum cross-correlated output is obtained when using twin detectors and applying equal bias to each tunnel junction. Furthermore, we show how the double-detector setup can be exploited to drastically reduce the added displacement noise of the oscillator.
description: 9 pages, 1 figure; v2: new Sec. V
Layering Connections: Reclaiming Abandoned Post Industrial Infrastructure
Creators: name: GESSNER, MICHAEL
Publisher: name: Digital Repository at the University of Maryland
Year: 2019
Subjects: subject: Architecture
subject: FOS: Civil engineering

description: Industrial Infrastructure fueled the birth and growth of countless small towns and cities throughout the United States. In many instances, the railroad served as the main source of employment. Local economies were often tied to the continued success of the railroad industry and mirrored their decline in the mid-20th century. The transition away from rail resulted in a network of abandoned rail lines, vacant rail yards, and unemployed towns. This thesis examines the Erie divisional rail yard in Port Jervis, New York and the voids left from abandoned industrial infrastructure. It proposes a solution that PROVIDES spaces that meet the community’s needs; ORIENTS the city as a regional port; RECONNECTS residents to the city’s past; and creates higher educational and TRAINING opportunities.
Canonical equivalence, quantization and anisotropic inflation in higher order theory of gravity
Creators: name: Debnath, Subhra
name: Sanyal, Abhik Kumar
Publisher: name: arXiv
Year: 2021
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We construct phase-space structure of a typical higher-order theory of gravity, in the background of anisotropic Bianchi-1 mini-superspace, following `Modified Horowitz Formalism' as well as applying `Dirac Algorithm' (after taking care of the divergent terms), and establish equivalence. Canonical quantization, and semiclassical approximation are performed to expatiate the fact that such a quantum theory transits successfully to a classical de-Sitter universe. Inflation has thereafter been studied. The numerical values of the inflationary parameters show excellent agreement with the latest released Planck's data.
description: 28 pages. 0 figures
Gravitational stability in the disk of M51
Creators: name: Hitschfeld, M.
name: Kramer, C.
name: Schuster, K. F.
name: Garcia-Burillo, S.
name: Stutzki, J.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Star formation laws, like i.e. the Schmidt law relating star formation rate and total gas density, have been studied in several spiral galaxies but the underlying physics are not yet well understood. M51, as a nearby face-on, grand design spiral galaxy studied in many line transitions, is an ideal target to study the connection between physical conditions of the gas and star formation activity. In this contribution we combine molecular, atomic, total gas and stellar surface densities and study the gravitational stability of the gas (Schuster et al.2007, Hitschfeld et al. in prep.). From our IRAM-30m 12 CO2-1 map and complementary HI-, Radio Continuum- and ACS-HST B-band-data we derive maps of the total gas density and the stellar surface density to study the gravitational stability of the gas via the Toomre Q parameter.
description: 4 pages, 3 Figures: Galaxies in the Local Volume, Sydney, Conference Proceedings Contribution
Two-Stage Framework for Seasonal Time Series Forecasting
Creators: name: Xu, Qingyang
name: Wen, Qingsong
name: Sun, Liang
Publisher: name: arXiv
Year: 2021
Subjects: subject: Machine Learning (cs.LG)
subject: Artificial Intelligence (cs.AI)
subject: Applications (stat.AP)
subject: FOS: Computer and information sciences

description: Seasonal time series Forecasting remains a challenging problem due to the long-term dependency from seasonality. In this paper, we propose a two-stage framework to forecast univariate seasonal time series. The first stage explicitly learns the long-range time series structure in a time window beyond the forecast horizon. By incorporating the learned long-range structure, the second stage can enhance the prediction accuracy in the forecast horizon. In both stages, we integrate the auto-regressive model with neural networks to capture both linear and non-linear characteristics in time series. Our framework achieves state-of-the-art performance on M4 Competition Hourly datasets. In particular, we show that incorporating the intermediate results generated in the first stage to existing forecast models can effectively enhance their prediction performance.
description: 5 pages, 2 figures, 3 tables, ICASSP 2021
Comment on "Isotope effect in high-Tc superconductors" (D. R. Harshman, J. D. Dow, and A. T. Fiory, Physical Review B v.77, 024523 (2008))
Creators: name: Alexandrov, A. S.
name: Zhao, G. M.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We show that the recent reinterpretation of oxygen isotope effects in cuprate superconductors by D. R. Harshman et al. is mathematically and physically incorrect violating the Anderson theorem and the Coulomb law.
description: 3 pages, 1 figure
A geometric analysis of the Maxwell field in a vicinity of a multipole particle and new special functions
Creators: name: Kijowski, Jerzy
name: Podles, Piotr
Publisher: name: arXiv
Year: 2007
Subjects: subject: Classical Physics (physics.class-ph)
subject: FOS: Physical sciences

description: A method of solving Maxwell equations in a vicinity of a multipole particle (moving along an arbitrary trajectory) is proposed. The method is based on a geometric construction of a trajectory-adapted coordinate system, which simplifies considerably the equations. The solution is given in terms of a series, where a new family of special functions arises in a natural way. Singular behaviour of the field near to the particle may be analyzed this way up to an arbitrary order. Application to the self-interaction problems in classical electrodynamics is discussed.
description: 33 pages, LaTeX file
Exploring the limits of the self consistent Born approximation for inelastic electronic transport
Creators: name: Lee, William
name: Sanvito, Stefano
Publisher: name: arXiv
Year: 2008
Subjects: subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: The non equilibrium Green function formalism is today the standard computational method for describing elastic transport in molecular devices. This can be extended to include inelastic scattering by the so called self-consistent Born approximation (SCBA), where the interaction of the electrons with the vibrations of the molecule is assumed to be weak and it is treated perturbatively. The validity of such an assumption and therefore of the SCBA is difficult to establish with certainty. In this work we explore the limitations of the SCBA by using a simple tight-binding model with the electron-phonon coupling strength $\rmα$ chosen as a free parameter. As model devices we consider Au mono-atomic chains and a $\rm{H_2}$ molecule sandwiched between Pt electrodes. In both cases our self-consistent calculations demonstrate a breakdown of the SCBA for large $\rmα$ and we identify a weak and strong coupling regime. For weak coupling our SCBA results compare closely with those obtained with exact scattering theory. However in the strong coupling regime large deviations are found. In particular we demonstrate that there is a critical coupling strength, characteristic of the materials system, beyond which multiple self-consistent solutions can be found depending on the initial conditions in the simulation. We attribute these features to the breakdown of the perturbative expansion leading to the SCBA.
description: 12 pages, 16 figures, 1 Table
Standard Model and New Physics: theoretical and experimental perspectives
Creators: name: Castro, Andrea
name: Corcella, Gennaro
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: In this summary we present the current status of the Standard Model of strong and electroweak interactions from the theoretical and experimental point of view. Some discussion is also devoted to the exploration of possible New Physics signals beyond the Standard Model.
description: 8 pages, 2 figures. Summary talk at IFAE 2008, Bologna, Italy, 26-28 March 2008
Coherent Modulation of Quasiparticle Scattering Rates in a Photoexcited Charge-Density-Wave System
Creators: name: Maklar, J.
name: Schüler, M.
name: Windsor, Y. W.
name: Nicholson, C. W.
name: Puppin, M.
name: Walmsley, P.
name: Fisher, I. R.
name: Wolf, M.
name: Ernstorfer, R.
name: Sentef, M. A.
name: Rettig, L.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We present a complementary experimental and theoretical investigation of relaxation dynamics in the charge-density-wave (CDW) system TbTe$_3$ after ultrafast optical excitation. Using time- and angle-resolved photoemission spectroscopy, we observe an unusual transient modulation of the relaxation rates of excited photocarriers. A detailed analysis of the electron self-energy based on a nonequilibrium Green's function formalism reveals that the phase space of electron-electron scattering is critically modulated by the photoinduced collective CDW excitation, providing an intuitive microscopic understanding of the observed dynamics and revealing the impact of the electronic band structure on the self-energy.
description: 6 pages, 4 figures