cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Brownian motion of a charged test particle near a reflecting boundary at finite temperature
Creators: name: Yu, Hongwei
name: Chen, Jun
name: Wu, Puxun
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We discuss the random motion of charged test particles driven by quantum electromagnetic fluctuations at finite temperature in both the unbounded flat space and flat spacetime with a reflecting boundary and calculate the mean squared fluctuations in the velocity and position of the test particle. We show that typically the random motion driven by the quantum fluctuations is one order of magnitude less significant than that driven by thermal noise in the unbounded flat space. However, in the flat space with a reflecting plane boundary, the random motion of quantum origin can become much more significant than that of thermal origin at very low temperature.
description: 11 pages,no figures, Revtex4
The Coil-Globule transition in self-avoiding active polymers
Creators: name: Das, S.
name: Kennedy, N.
name: Cacciuto, A.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Computational Physics (physics.comp-ph)
subject: FOS: Physical sciences

description: We perform numerical simulations of an active fully flexible self-avoiding polymer as a function of the quality of the embedding solvent described in terms of an effective monomer-monomer interaction. Specifically, by extracting the Flory exponent of the active polymer under different conditions, we are able to pin down the location of the coil-globule transition for different strength of the active forces. Remarkably, we find that a simple rescaling of the temperature is capable of qualitatively capture the dependence of the $Θ$-point of the polymer with the amplitude of the active fluctuations. We discuss the limits of this mapping, and suggest that a negative active pressure between the monomers, not unlike the one that has already been found in suspensions of active hard spheres, may also be present in active polymers.
Complex ICA using Nonlinear Functions
Creators: name: Novey, Michael
Publisher: name: Maryland Shared Open Access Repository
Year: 2009
Subjects: Complex
Independent component analysis
Nonlinear filtering
Optimization

description: Independent component analysis for separating complex-valued signals has found utility in many applications such as communications, analysis of functional  magnetic resonance imaging and electroencephalography data, face recognition, and radar beamforming. In this dissertation, we show the importance of matching the cost function to the source density in the complex case by showing the connection between maximization of non-Gaussianity, maximum likelihood, and minimization of mutual information. This connection emphasizes that optimal source separation algorithms must consider the bivariate distribution especially for the case of noncircular sources, \textit{i.e.,} sources that are not rotation invariant. Based on this result, we develop four density-matching ICA algorithms that are well suited for a wide range of circular and noncircular distributions. These algorithms provide density matching by: explicitly matching the source densities using a mixture model, adaptive on-line density estimation, using complex transcendental functions that provide asymmetric responses, or modifying the optimization method specifically for the noncircular case. Along with the derivations of these algorithms, we also present a rigorous local stability analysis of the cost functions that explicitly show the effects of noncircularity on performance, or more specifically, defines the space of noncircular distributions that are unstable using the algorithm. A convergence analysis shows that the fixed-point optimization algorithms we derive in this study converge quadratically with circular or noncircular sources. We test the effectiveness of the four density-matching algorithms using simulations and real-world radar data and wind data. The results show that density-matching provides improved performance as compared with current complex-valued independent component analysis methods. The results also quantify the advantages to explicitly matching and estimating the source densities where in each case a more efficient estimator is realized. To effectively test the algorithms, a method for generating these varied distributions is necessary. To this end, we extend the bivariate generalized Gaussian distribution to the fully-complex case, present a maximum likelihood estimate for its shape and covariance parameters, provide a method for generating complex random variables from its distribution, and derive a generalized likelihood ratio test for testing whether a signal is noncircular or Gaussian.
Constraining TeVeS Gravity as Effective Dark Matter and Dark Energy
Creators: name: Zhao, HongSheng
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: The phenomena customly described with the standard $Λ$CDM model are broadly reproduced by an extremely simple model in TeVeS, Bekenstein's (2004) modification of General Relativity motivated by galaxy phenomenology. Our model can account for the acceleration of the universe seen in SNeIa distances without a cosmological constant, and the accelerations seen rotation curves of nearby spiral galaxies and gravitational lensing of high-redshift elliptical galaxies without cold dark matter. The model is consistent with BBN and the neutrino mass. The TeVeS scalar field is shown to play the effective dural roles of Dark Matter and Dark Energy with the amplitudes of the effects controled by a $μ$-function of the scalar field, called the $μ-$essence here. We also discuss outliers to the theory's predictions on multi-imaged galaxy lenses and outliers on sub-galaxy scale.
description: 10 pages, invited review for "Quantum to Cosmology: Fundamental Physics in Space", proceedings editted by Ulf Isaelsson, Slava Turyshev
title: Nu’usi und Nggela, Salomonen. Neue archäologische Forschungen auf den Salomonen Inseln. Die Ergebnisse der Feldkampagnen 2020 und 2021
title: Nu’usi und Nggela, Salomonen. Neue archäologische Forschungen auf den Salomonen Inseln. Die Ergebnisse der Feldkampagnen 2020 und 2021
titleType: Subtitle
Creators: name: Bemama, Grinta
name: Gegeu, Reubenson
name: Kiko, Lawrence
name: Manebosa, Stephen
name: Moser, Johannes
Publisher: name: Deutsches Archäologisches Institut
Year: 2021
Subjects: subject: Platzhalter

description: e-Forschungsberichte, Faszikel 2 (2021)
description: The current research project is designed to focus on archaeological ­investigations on the pre- and protohistory of the Solomon Islands. In 2020 and 2021, two new research programs were initialized and field work was conducted on the island of Nu’usi in the Maramasike Passage and on the Nggela Island group in Central Province. The archaeological survey on Nu’usi yielded various features in terms of deposited flint nodules, zones of waste flakes and lithic core adzes as indications of knapping activities from the tool production and also architectural structures such as artificial heaps and ­footpaths. The archaeological survey on Nggela Island resulted in the ­discovery of eight caves and ten rock shelters. A great number of these sites are showing evidences of human presence in prehistoric times.
Stabilization of Finite-Energy Gottesman-Kitaev-Preskill States
Creators: name: Royer, Baptiste
name: Singh, Shraddha
name: Girvin, S. M.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We introduce a new approach to Gottesman-Kitaev-Preskill (GKP) states that treats their finite-energy version in an exact manner. Based on this analysis, we develop new qubit-oscillator circuits that autonomously stabilize a GKP manifold, correcting errors without relying on qubit measurements. Finally, we show numerically that logical information encoded in GKP states is very robust against typical oscillator noise sources when stabilized by these new circuits.
description: Main text: 6 pages, 4 figures. Supplemental material: 27 pages, 13 figures
Constraint Generation and Reasoning in OWL
Creators: name: Briggs, Thomas Henry
Publisher: name: Maryland Shared Open Access Repository
Year: 2008
Subjects: Constraint
Default Reasoning
OWL

description: The majority of OWL ontologies in the emerging Semantic Web are constructed from properties that lack domain and range constraints.  Constraints in OWL are different from the familiar uses in programming languages and databases. They are actually type assertions that are made about the individuals which are connected by the property.  Because they are type assertions these assertions can add vital information to the individuals involved and give information on how the defining property may be used.  Three different automated generation techniques are explored in this research: disjunction, least-common named subsumer, and vivification.  Each algorithm is compared for the ability to generalize, and the performance impacts with respect to the reasoner.  A large sample of ontologies from the Swoogle repository are used to compare real-world performance of these techniques.  Using generated facts is a type of default reasoning.  This may conflict with future assertions to the knowledge base.  While general default reasoning is non-monotonic and undecidable a novel approach is introduced to support efficient contraction of the default knowledge.  Constraint generation and default reasoning, together, enable a robust and efficient generation of domain and range constraints which will result in the inference of additional facts and improved performance for a number of Semantic Web applications.
Enhanced Molecular Orientation Induced by Molecular Anti-Alignment
Creators: name: Gershnabel, E.
name: Averbukh, I. Sh.
name: Gordon, Robert J.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: We explore the role of laser induced anti-alignment in enhancing molecular orientation. A field-free enhanced orientation via anti-alignment scheme is presented, which combines a linearly polarized femtosecond laser pulse with a half-cycle pulse. The laser pulse induces transient anti-alignment in the plane orthogonal to the field polarization, while the half-cycle pulse leads to the orientation. We identify two qualitatively different enhancement mechanisms depending on the pulse order, and optimize their effects using classical and quantum models both at zero and non-zero temperature.
Community Detection in Twitter
Creators: name: Kewalramani, Mohit Naresh
Publisher: name: Maryland Shared Open Access Repository
Year: 2011
Subjects: clusters
community
groups
twitter

description: Twitter has evolved into a source of social, political and real time information in addition to being a means of mass-communication and marketing. Monitoring and analyzing information on Twitter can lead to invaluable insights, which might otherwise be hard to get using conventional media resources. An important task in analyzing highly networked information sources like twitter is to identify communities that are formed. A community on twitter can be defined as a set of users that are more similar to other members than to non-members. We present a technique to devise a similarity metric between any two users on twitter based on the similarity of their content, links and metadata. The link structure on Twitter can be characterized using the twitter notion of followers, being followed and the @Mentions, @Reply and @RT tags in tweets. Content similarity is characterized by the words in the tweets combined with the hash-tags they are annotated with. Meta-data similarity includes similarity based on other sources of user information such as location, age and gender. We then use this similarity metric to cluster users into communities using spectral and bottom-up agglomerative hierarchical clustering. We evaluate the performance of clustering using different similarity measures on different types of datasets. We also present a heuristic to find communities in twitter that take advantage of the network characteristics of twitter.
DNA Confined in Nanochannels: Hairpin Tightening by Entropic Depletion
Creators: name: Odijk, Theo
Publisher: name: arXiv
Year: 2006
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: A theory is presented of DNA hairpins enclosed in a nanochannel. A hairpin becomes constrained as it approaches the wall of a channel which leads to an entropic force causing the hairpin to tighten. The free energy of the hairpin computed in the classical limit is significantly larger than what one would expect. As a result, the distance between hairpins or the global persistence length is often tens of micrometers long and may even reach mm sizes for 10 nm thin channels. The hairpin shape and size, and the DNA elongation are computed for nanoslits, and circular and square nanoschannels. A comparison with experiment is given.
description: 13 pages, 4 figures
The impact of mood on the endorsement of rumination: an exploration of the association between cognitive biases and behaviour
Creators: name: Pidcock, Madeleine Marie
Publisher: name: The Australian National University
Year: 2018

description: Reliable and robust methods of assessment are crucial to best practise within research and clinical settings. Although there are a number of benefits associated with the use of self-report questionnaires there is cause to examine how accurately they measure the frequency and content of mental processes. In particular, little attention has been paid to the potential influence of mood to effect endorsement behaviour. The existence of mood related variation in response styles would represent a major threat to the correct interpretation of self-report data. In clinical settings this threat is further increased due to samples of respondents who are expected to experience variations in mood across the course of therapy and relevant measurement points (e.g. pre-post treatment outcome measures). This dissertation sought to assess how mood may influence the endorsement of ruminative behaviours. The choice to examine rumination was threefold, rumination has developed as a key construct in understanding cognitive vulnerabilities to depression, it is solely assessed via self-report methodologies, and concerns have been raised that existing questionnaires are overly negative in tone. This is of particular significance given that there is a large body of literature demonstrating that depression is characterised by cognitive biases for negatively valenced stimuli. Such biases have been demonstrated in attention, memory, and interpretation -cognitive processes that are intrinsic to endorsement behaviour. If negative affect influences endorsement of ruminative behaviours, the aforementioned cognitive biases may play a role. This was explored over five studies. Results demonstrated that respondents are sensitive to question valence, and that subtle changes in wording can inflate item negativity. Furthermore, results indicated that experimentally induced negative mood increased perception of item negativity and endorsement of ruminative items. The final two studies highlight possible options for quantifying and minimising the effects of mood related changes in endorsement via the development and validation of a novel measure for endorsement bias, and support for the incorporation of informant-reports in the assessment process.
Increasing teacher effectiveness : sensitivity and clarity in a multicultural classroom
Creators: name: Caine, Cynthia Anne
Publisher: name: University of British Columbia
Year: 2009

description: The purpose of this research was to investigate the hypothesis that in order to provide equal educational access and outcomes for all students, an emphasis on teacher sensitivity and clarity of instruction is required in a multicultural classroom. This study offers an in-depth look at varying levels of narrowly defined dominant cultural capital between two different cultural groups within a grade 12 Economics classroom, during May and June of 1996. And if differences in the quantity of narrowly defined cultural capital do, in fact exist, can 'bridging' these knowledge gaps be achieved through clarity of instruction, so that all groups, after receiving the requisite cultural capital, can construct new knowledge effectively. Since the research was exploratory, a qualitative case study design drawing on ethnographic approaches was employed. Interviews were the primary tool chosen for data collection; the secondary tools were documents and the researcher's field notes. This study has revealed that the levels of narrowly defined cultural capital were different between cultures, and that the 'playing field' in a multicultural classroom may be levelled to a significant extent with minimal explanations of the necessary cultural capital. This research highlights the importance of teachers' ongoing assessment of their students knowledge in areas that are non-traditional, and where the knowledge is assumed by the teacher to already be in place. The study concludes with some suggestions for teacher practice and for future research in the field.
title: SET Effects on Quasi Delay Insensitive and Synchronous Circuits
Creators: name: Tabassam, Zaheer
name: Steininger, Andreas
Publisher: name: TU Wien
Year: 2023
Subjects: single event transient
robustness
Asynchronous Logic

description: Due to their unbounded data accepting windows asynchronous circuits seem to be more susceptible to environmental effects than their synchronous counterparts with their strict data latching protocol. The technology advancement makes single event transients (SETs) more of a concern towards reliable operation. To better understand the properties of the mentioned classes we present their behaviour under the influence of SETs in a more detailed view that helps to visualize their unseen characteristics. For comparison we propose a way of fault injection where the length of a fault pulse is not fixed, calculated based on maximum gate delay, but related to the circuit’s computation steps instead. The analysis concludes that asynchronous quasi delayinsensitive (QDI) circuits show better resilience against SETs due to two main reasons: (1) if realized with a 4-phase handshake protocol they are 95 to 97% resilient to negative fault pulses (2) the susceptibility of a circuit is largely unchanged for increasing fault length because of the causality underlying the QDI principle. Our analysis provides insights leading towards more resilient QDI circuits: if we only make a circuit or specific gates better resist ”1” faults, we are fully resilient towards the single event transient (SET)s because ”0” faults are already filtered out by its inherent behaviour. This is also beneficial for area efficiency; as asynchronous circuits often require already double or more area and computation time compared to synchronous circuits, adding extra SET mitigation with double-up or other buffer redundant techniques tends to result in painful overheads. Being able to focus the protection to ”1” faults, as indicated by our analysis, can hence yield important savings.
Constraining Information Flow in Social Networks with Privacy Policies
Creators: name: Chormale, Audumbar D.
Publisher: name: Maryland Shared Open Access Repository
Year: 2009
Subjects: mobile
Privacy
Social networking

description: Online social networking systems are a phenomenon that has grown exponentially over the past few years. These systems provide platforms for people to easily share information, especially about themselves and about their interests. With the recent emergence of geolocation technologies, social networking can allow users to interact relative to location and time. Most systems began with few or no privacy controls and have gradually been adding and enhancing them to meet the demands of their users. Until recently, for example, Facebook had only a binary notion of privacy - a friend could see everything. This has lead to several well known mishaps where information people have voluntarily put online has been used to their detriment. There is a need of strong privacy control mechanisms that factor in the dynamic changes in the user context relative to attributes like location and time. In this paper, we present a system that adds rich privacy support to such systems. We describe a prototype implementation typical of applications that many university campuses and startups are creating. It aggregates social media from a variety of online sources as well as sources internal to the campus intranet. We show how policy framework based on semantic web technologies can be effectively used to devise better privacy control mechanisms that factor in the dynamic user context. The implementation uses the Rein framework and the AIR framework to provide access control and justification support. We validate our architecture in the prototype implementation and describe various cases of privacy rules definitions in the system.
Continuous Curve Textures
Creators: name: Tu, Peihan
name: Wei, Li-Yi
name: Yatani, Koji
name: Igarashi, Takeo
name: Zwicker, Matthias
Publisher: name: arXiv
Year: 2020
Subjects: subject: Graphics (cs.GR)
subject: FOS: Computer and information sciences

description: Repetitive patterns are ubiquitous in natural and human-made objects, and can be created with a variety of tools and methods. Manual authoring provides unmatched degree of freedom and control, but can require significant artistic expertise and manual labor. Computational methods can automate parts of the manual creation process, but are mainly tailored for discrete pixels or elements instead of more general continuous structures. We propose an example-based method to synthesize continuous curve patterns from exemplars. Our main idea is to extend prior sample-based discrete element synthesis methods to consider not only sample positions (geometry) but also their connections (topology). Since continuous structures can exhibit higher complexity than discrete elements, we also propose robust, hierarchical synthesis to enhance output quality. Our algorithm can generate a variety of continuous curve patterns fully automatically. For further quality improvement and customization, we also present an autocomplete user interface to facilitate interactive creation and iterative editing. We evaluate our methods and interface via different patterns, ablation studies, and comparisons with alternative methods.
Letter from Frank Hewer to [James] Goldie, September 8, 1909
Creators: name: Hewer, Frank Algernon
Publisher: name: The University of British Columbia
Year: 2017

description: Letter to James Goldie from Frank Hewer, dated September 8, 1909; written on The Empress Hotel letterhead. The letter is regarding ongoing financial issues and questions between the two pertaining to the sale of the Ranche to Goldie.
Thermal Properties of Rung Disordered Two-leg Quantum Spin Ladders: Quantum Monte Carlo Study
Creators: name: Kanbur, Ulvi
name: Polat, Hamza
name: Vatansever, Erol
Publisher: name: arXiv
Year: 2020
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: A two-leg quenched random bond disordered antiferromagnetic spin$-1/2$ Heisenberg ladder system is investigated by means of stochastic series expansion (SSE) quantum Monte Carlo (QMC) method. Thermal properties of the uniform and staggered susceptibilities, the structure factor, the specific heat and the spin gap are calculated over a large number of random realizations in a wide range of disorder strength. According to our QMC simulation results, the considered system has a special temperature point at which the specific heat take the same value regardless of the strength of the disorder. Moreover, the uniform susceptibility is shown to display the same character except for a small difference in the location of the special point. Finally, the spin gap values are found to decrease with increasing disorder parameter and the smallest gap value found in this study is well above the weak coupling limit of the clean case.
description: 15 pages, 9 figures
Probing the cosmic acceleration history and the properties of dark energy from the ESSENCE supernova data with a model independent method
Creators: name: Wu, Puxun
name: Yu, Hongwei
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: With a model independent method the expansion history $H(z)$, the deceleration parameter $q(z)$ of the universe and the equation of state $w(z)$ for the dark energy are reconstructed directly from the 192 Sne Ia data points, which contain the new ESSENCE Sne Ia data and the high redshift Sne Ia data. We find that the evolving properties of $q(z)$ and $w(z)$ reconstructed from the 192 Sne Ia data seem to be weaker than that obtained from the Gold set, but stronger than that from the SNLS set. With a combination of the 192 Sne Ia and BAO data, a tight constraint on $Ω_{m0}$ is obtained. At the $1σ$ confidence level $Ω_{m0}=0.278^{+0.024}_{-0.023}$, which is highly consistent with that from the Gold+BAO and SNLS+BAO.
description: 11 pages, 5 figures, to appear in JCAP
Connectivity Restoration in Wireless Sensor Networks using Steiner Tree Approximations
Creators: name: Waknis, Rahul Mukund
Publisher: name: Maryland Shared Open Access Repository
Year: 2010
Subjects: connectivity restoration
sensor networks
steiner tree
wireless networks

description: Wireless sensor nodes are symbiotic when deployed in an activity region and heavily rely on each other for successful transmission of data. Therefore, failure of some nodes can possibly partition the network. Since unmanned operation is one of the primary properties of these nodes, there needs to be a way in which these nodes can collectively maintain connectivity and resolve any reachability problem that may be faced when a node fails. Different approaches have been proposed in the literature to address this issue. However, most published approaches are based on a single underlying principle of trying to replace the failed node without considering the possible fact that the location of the failed node might not have been optimal and which could have been the reason for its failure. These approaches also tend to trigger a cascaded relocation of many nodes resulting in increased overhead. This thesis presents a novel solution that pursues rearrangement of nodes to restore connectivity while limiting the scope of the recovery to the vicinity of the failed node. Whenever a node fails, its neighbors reposition themselves to not only re-establish data paths but also ensure that they are connected in the best possible way. The connectivity restoration is modeled as a variant of the Steiner tree formation problem and solved using novel heuristics. The proposed approach is validated through simulation and is shown to outperform existing schemes.
title: Maikop, Russische Föderation. Neues zur Domestikation des Pferdes. Die Anfänge führen in den Kaukasus während des 4. Jahrtausends v. Chr. Aktuelle Resultate 2021
title: Maikop, Russische Föderation. Neues zur Domestikation des Pferdes. Die Anfänge führen in den Kaukasus während des 4. Jahrtausends v. Chr. Aktuelle Resultate 2021
titleType: Subtitle
Creators: name: Hansen, Svend
name: Orlando, Ludovic
name: Reinhold, Sabine
name: Belinskij, Andrej
name: Kalmykov, Alexej
Publisher: name: Deutsches Archäologisches Institut
Year: 2021
Subjects: subject: Platzhalter

description: e-Forschungsberichte, Faszikel 2 (2021)
description: A new palaeogenetic study by Ludovic Orlando and his team at the Centre for Anthropobiology and Genomics of Toulouse, CNRS / Université Toulouse III – Paul Sabatier, in which also scientists from the DAI were involved, has now shed new light on the horse domestication. The study published in Nature 2021, which was carried out within the framework of the ERC project »PEGASUS«, shows that there were in fact two different domesti­cation ­processes. The first time horses were domesticated was in the mid-4th ­millennium BC in the Kazakh steppe. The best known site of the first do­mestication (DOM1) is Botai. However, these early domestic horses were replaced by a genetically distinct second domestication type (DOM2), which became dominant in lager parts of western Eurasia around 2200 BC. At ­present, the oldest ancestor of the new DOM2 horse may be considered to be a horse found in a burial mound of the Aygurskiy 2 necropolis in the steppe zone north of the Caucasus, dated to the second third of the 4th ­millennium BC.
Multifractal fluctuations in the survival probability of an open quantum system
Creators: name: Facchini, Angelo
name: Tomadin, Andrea
name: Wimberger, Sandro M.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: We predict a multifractal behaviour of transport in the deep quantum regime for the opened $δ-$kicked rotor model. Our analysis focuses on intermediate and large scale correlations in the transport signal and generalizes previously found parametric {\em mono}-fractal fluctuations in the quantum survival probability on small scales.
description: 8 pages, 3 figures, 2 tables. Physica A, accepted 2006
Observations of the Lyman-$α$ Universe
Creators: name: Ouchi, Masami
name: Ono, Yoshiaki
name: Shibuya, Takatoshi
Publisher: name: arXiv
Year: 2020
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: Hydrogen Lyman-$α$ (Ly$α$) emission has been one of the major observational probes for the high redshift universe, since the first discoveries of high-$z$ Ly$α$ emitting galaxies in the late 1990s. Due to the strong Ly$α$ emission originated by resonant scattering and recombination of the most-abundant element, Ly$α$ observations witness not only HII regions of star formation and AGN but also diffuse HI gas in the circum-galactic medium (CGM) and the inter-galactic medium (IGM). Here we review Ly$α$ sources, and present theoretical interpretations reached to date. We conclude that: 1) A typical Ly$α$ emitter (LAE) at $z\gtrsim 2$ with a $L^*$ Ly$α$ luminosity is a high-$z$ counterpart of a local dwarf galaxy, a compact metal-poor star-forming galaxy (SFG) with an approximate stellar (halo) mass and star-formation rate of $10^{8-9} M_\odot$ ($10^{10-11} M_\odot$) and $1-10 M_\odot$ yr$^{-1}$, respectively; 2) High-$z$ SFGs ubiquitously have a diffuse Ly$α$ emitting halo in the CGM extending to the halo virial radius and beyond; 3) Remaining neutral hydrogen at the epoch of reionization makes a strong dimming of Ly$α$ emission for galaxies at $z>6$ that suggest the late reionization history. The next generation large telescope projects will combine Ly$α$ emission data with HI Ly$α$ absorptions and 21cm radio data that map out the majority of hydrogen (HI+HII) gas, uncovering the exchanges of i) matter by outflow/inflow and ii) radiation, relevant to cosmic reionization, between galaxies and the CGM/IGM.
description: 45 pages, 18 figures. Invited review published in Annual Reviews of Astronomy and Astrophysics. See https://www.annualreviews.org/doi/abs/10.1146/annurev-astro-032620-021859 for updated version
Geometrical Distance Determination using Type I X-ray Bursts
Creators: name: Thompson, Thomas W. J.
name: Rothschild, Richard E.
name: Tomsick, John A.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: With the excellent angular resolution of the Chandra X-ray Observatory, it is possible to geometrically determine the distance to variable Galactic sources, based on the phenomenon that scattered radiation appearing in the X-ray halo has to travel along a slightly longer path than the direct, unscattered radiation. By measuring the delayed variability, constraints on the source distance can be obtained if the halo brightness is large enough to dominate the point spread function (PSF) and to provide sufficient statistics. The distance to Cyg X-3, which has a quasi-sinusoidal light curve, has been obtained with this approach by Predehl et al. Here we examine the feasibility of using the delayed signature of type I X-ray bursts as distance indicators. We use simulations of delayed X-ray burst light curves in the halo to find that the optimal annular region and energy band for a distance measurement with a grating observation is roughly 10-50" and 1-5 keV respectively, assuming Chandra's effective area and PSF, uniformly distributed dust, the input spectrum and optical depth to GX 13+1, and the Weingartner & Draine interstellar grain model. We find that the statistics are dominated by Poisson noise rather than systematic uncertainties, e.g., the PSF contribution to the halo. Using Chandra, a distance measurement to such a source at 4 (8) kpc could be made to about 23% (30%) accuracy with a single burst with 68% confidence. By stacking many bursts, a reasonable estimate of systematic errors limit the distance measurement to about 10% accuracy.
description: 7 pages, 4 figures; Accepted for publication in ApJ
Search for high-redshift blazars with Fermi/LAT
Creators: name: Kreter, M.
name: Gokus, A.
name: Krauß, F.
name: Kadler, M.
name: Ojha, R.
name: Buson, S.
name: Wilms, J.
name: Böttcher, M.
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: High-$z$ blazars (z $\geq 2.5$) are the most powerful class of persistent $γ$-ray sources in the Universe. These objects possess the highest jet powers and luminosities and have black hole masses often in excess of $10^9$ solar masses. In addition, high-$z$ blazars are important cosmological probes and serve as test objects for blazar evolution models. Due to their large distance, their high-energy emission typically peaks below the GeV range, which makes them difficult to study with Fermi/LAT. Therefore, only the very brightest objects are detectable and, to date, only a small number of high-z blazars have been detected with Fermi/LAT. In this work, we studied the monthly binned long-term $γ$-ray emission of a sample of 176 radio and optically detected blazars that have not been reported as known $γ$-ray sources in the 3FGL catalog. In order to account for false-positive detections, we calculated monthly Fermi/LAT light curves for a large sample of blank sky positions and derived the number of random fluctuations that we expect at various test statistic (TS) levels. For a given blazar, a detection of TS > 9 in at least one month is expected $\sim 15\%$ of the time. Although this rate is too high to secure detection of an individual source, half of our sample shows such single-month $γ$-ray activity, indicating a population of high-energy blazars at distances of up to z=5.2. Multiple TS > 9 monthly detections are unlikely to happen by chance, and we have detected several individual new sources in this way, including the most distant $γ$-ray blazar, BZQ J1430+4204 (z = 4.72). Finally, two new $γ$-ray blazars at redshifts of z = 3.63 and z = 3.11 are unambiguously detected via very significant (TS > 25) flares in individual monthly time bins.
title: Prilep, North Macedonia. House taskscapes in the Early Neolithic of the Pelagonia Valley: micro-refuse analyses. First results of the Campaign 2019
title: Prilep, North Macedonia. House taskscapes in the Early Neolithic of the Pelagonia Valley: micro-refuse analyses. First results of the Campaign 2019
titleType: Subtitle
Creators: name: Antolín, Ferran
name: Dimitrijević , Vesna
name: Naumov, Goce
name: Sabanov, Amalia
name: Soteras, Raül
Publisher: name: Deutsches Archäologisches Institut
Year: 2021
Subjects: subject: Archeobotany
subject: Archaeozoology
subject: Neolithic
subject: Activity analysis

description: e-Forschungsberichte, Faszikel 2 (2021)
description: New research, which involves the systematic collection of sediment samples, their treatment with the wash-over method, extraction of micro-refuse, and their subsequent analysis, started being implemented at archaeological sites in the Pelagonia Valley (North Macedonia) in the summer of 2019. Three Early Neolithic (ca. 6000–5800 cal BC) sites are being investigated and compared, with a focus on archaeobotanical materials, but also on other ­environmental and palaeoeconomic evidence. This paper presents the methodology applied and the first results from a series of samples (those for which the analyses were completed in 2021) from the 2019 campaign at the site of Vrbjanska Čuka. The goal is to illustrate the potential of micro-refuse analysis of samples coming from house contexts.
Astrophysical and Cosmological Tests of Quantum Theory
Creators: name: Valentini, Antony
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Astrophysics (astro-ph)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We discuss several proposals for astrophysical and cosmological tests of quantum theory. The tests are motivated by deterministic hidden-variables theories, and in particular by the view that quantum physics is merely an effective theory of an equilibrium state. The proposed tests involve searching for nonequilibrium violations of quantum theory in: primordial inflaton fluctuations imprinted on the cosmic microwave background, relic cosmological particles, Hawking radiation, photons with entangled partners inside black holes, neutrino oscillations, and particles from very distant sources.
description: 25 pages. Amendment to section 7. Contribution to: "The Quantum Universe", special issue of Journal of Physics A, dedicated to Prof. G.-C. Ghirardi on the occasion of his seventieth birthday
Periodicity detection in AGN with the boosted tree method
Creators: name: Soltau, S. B.
name: Botti, L. C. L.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Computational Physics (physics.comp-ph)
subject: FOS: Physical sciences

description: We apply a machine learning algorithm called XGBoost to explore the periodicity of two radio sources: PKS~1921-293 (OV~236) and PKS~2200+420 (BL~Lac), both radio frequency dataset obtained from University of Michigan Radio Astronomy Observatory (UMRAO), at 4.8 GHz, 8.0 GHz, and 14.5 GHz, between 1969 to 2012. From this methods, we find that the XGBoost provides the opportunity to use a machine learning based methodology on radio dataset and to extract information with strategies quite different from those traditionally used to treat time series and to obtain periodicity through the classification of recurrent events. The results were compared with other methods from others works that examined the same dataset and exhibit good agreement with them.
description: Submitted to the Revista Mexicana de Astronom\'ia y Astrof\'isica in Aug 03, 2020. Accepted oct 15, 2020. Will appear in v. 57, n.1, April 2021
R package vignette “rRiskGEvec.pdf” from Quantifying the risk of vector-borne disease transmission attributable to genetically modified vectors
Creators: name: Hosack, Geoffrey R.
name: Ickowicz, Adrien
name: Hayes, Keith R.
Publisher: name: The Royal Society
Year: 2021
Subjects: subject: Statistics
subject: FOS: Mathematics
subject: 60102 Bioinformatics
subject: FOS: Computer and information sciences
subject: 60113 Synthetic Biology
subject: FOS: Biological sciences
subject: 10202 Biological Mathematics

description: This vignette summarises results, code and data from the accompanying R package.
Sub-damped Lyman alpha systems in the XQ-100 survey II -- Chemical evolution at 2.4
Creators: name: Berg, Trystyn A. M.
name: Fumagalli, Michele
name: D'Odorico, Valentina
name: Ellison, Sara L.
name: Lopez, Sebastian
name: Becker, George D.
name: Christensen, Lise
name: Cupani, Guido
name: Denney, Kelly D.
name: Sanchez-Ramirez, Ruben
name: Worseck, Gabor
Publisher: name: arXiv
Year: 2021
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We present the measured gas-phase metal column densities in 155 sub-damped Lyman alpha systems (subDLAs) with the aim to investigate the contribution of subDLAs to the chemical evolution of the Universe. The sample was identified within the absorber-blind XQ-100 quasar spectroscopic survey over the redshift range 2.4<=z<=4.3. Using all available column densities of the ionic species investigated (mainly CIV, SiII, MgII, SiIV, AlII, FeII, CII, and OI; in order of decreasing detection frequency), we estimate the ionization-corrected gas-phase metallicity of each system using Markov Chain Monte Carlo techniques to explore a large grid of Cloudy ionization models. Without accounting for ionization and dust depletion effects, we find that the HI-weighted gas-phase metallicity evolution of subDLAs are consistent with damped Lyman alpha systems (DLAs). When ionization corrections are included, subDLAs are systematically more metal-poor than DLAs (between ~0.5 sigma and ~3 sigma significance) by up to ~1.0 dex over the redshift range 3<=z<=4.3. The correlation of gas-phase [Si/Fe] with metallicity in subDLAs appears to be consistent with that of DLAs, suggesting that the two classes of absorbers have a similar relative dust depletion pattern. As previously seen for Lyman limit systems, the gas-phase [C/O] in subDLAs remains constantly solar for all metallicities indicating that both subDLAs and Lyman limit systems could trace carbon-rich ejecta, potentially in circumgalactic environments.
description: Accepted for publication in MNRAS. 64 pages (20 pages of main text, 44 pages of Figures in appendix). Machine-readable versions of Tables 2 and 3 are available in the source files or available online on MNRAS
Statistical analysis of a dynamical multifragmentation path
Creators: name: Raduta, A. H.
name: Colonna, M.
name: Baran, V.
name: Di Toro, M.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: A microcanonical multifragmentation model (MMM) is used for investigating whether equilibration really occurs in the dynamical evolution of two heavy ion collisions simulated via a stochastic mean field approach (SMF). The standard deviation function between the dynamically obtained freeze-out fragment distributions corresponding to the reaction $^{129}$Xe+$^{119}$Sn at 32 MeV/u and the MMM ones corresponding to a wide range of mass, excitation energy, freeze-out volume and nuclear level density cut-off parameter shows a unique minimum. A distinct statistically equilibrated stage is identified in the dynamical evolution of the system.
description: 5 pages, 3 figures
Second-harmonic generation enhancement in monolayer transition-metal dichalcogenides by an epsilon-near-zero substrate
Creators: name: Vianna, Pilar G.
name: Almeida, Aline dos S.
name: Gerosa, Rodrigo M.
name: Bahamon, Dario A.
name: de Matos, Christiano J. S.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: Monolayer transition-metal dichalcogenides (TMDCs) present high second-order optical nonlinearity, which is extremely desirable for, e.g., frequency conversion in nonlinear photonic devices. On the other hand, the atomic thickness of 2D materials naturally leads to low frequency converted intensities, highlighting the importance to design structures that enhance the nonlinear response for practical applications. A number of methods to increase the pump electric field at the 2D material has been reported, relying on complex plasmonic and/or metasurface structures. Here, we take advantage of the fact that unstructured substrates with a low refractive index naturally maximize the pump field at a dielectric interface, offering a simple means to promote enhanced nonlinear optical effects. In particular, we measured second harmonic generation (SHG) in MoS2 and WS2 on fluorine tin oxide (FTO), which presents an epsilon-near-zero point near our 1550-nm pump wavelength. Polarized SHG measurements reveal an SHG intensity that is one order of magnitude higher on FTO than on a glass substrate.
description: 21 pages (main manuscript ans supporting material), 16 figures
title: Baalbek, Libanon. Feldforschungen und Konservierungsarbeiten. Die Arbeiten des Jahres 2020
title: Baalbek, Libanon. Feldforschungen und Konservierungsarbeiten. Die Arbeiten des Jahres 2020
titleType: Subtitle
Creators: name: van Ess, Margarete
name: Nàdor, Julia
name: Burwitz, Henning
name: Wienholz, Holger
Publisher: name: Deutsches Archäologisches Institut
Year: 2021
Subjects: subject: Platzhalter

description: e-Forschungsberichte, Faszikel 2 (2021)
description: In Baalbek, the development of the city from a prehistoric tell to a Roman city and its constant metamorphosis into the early modern period has been the subject of research for many years. Adapting to travel and work oppor­tunities and taking into account the COVID-19 pandemic, fieldwork in Baalbek also took place in 2020, but in several working stages and for a shorter period than planned. Work continued in three areas: with photographic and photogrammetric documentation in the Roman sanctuary of Jupiter, with exca­vations in the medieval quarter in the so-called Bustan Nassif, and for the preparation of conservation measures in the ›Bustan el-Khan‹ with its public buildings from the Roman period.
Instability of a stalled accretion shock: evidence for the advective-acoustic cycle
Creators: name: Foglizzo, T.
name: Galletti, P.
name: Scheck, L.
name: Janka, H. -Th.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We analyze the linear stability of a stalled accretion shock in a perfect gas with a parametrized cooling function L ~ rho^{beta-alpha} P^alpha. The instability is dominated by the l=1 mode if the shock radius exceeds 2-3 times the accretor radius, depending on the parameters of the cooling function. The growth rate and oscillation period are comparable to those observed in the numerical simulations of Blondin & Mezzacappa (2006). The instability mechanism is analyzed by separately measuring the efficiencies of the purely acoustic cycle and the advective-acoustic cycle. These efficiencies are estimated directly from the eigenspectrum, and also through a WKB analysis in the high frequency limit. Both methods prove that the advective-acoustic cycle is unstable, and that the purely acoustic cycle is stable. Extrapolating these results to low frequency leads us to interpret the dominant mode as an advective-acoustic instability, different from the purely acoustic interpretation of Blondin & Mezzacappa (2006). A simplified characterization of the instability is proposed, based on an advective-acoustic cycle between the shock and the radius r_nabla where the velocity gradients of the stationary flow are strongest. The importance of the coupling region in this mechanism calls for a better understanding of the conditions for an efficient advective-acoustic coupling in a decelerated, nonadiabatic flow, in order to extend these results to core-collapse supernovae.
description: 29 pages, 18 figures, to appear in ApJ (1 new Section, 2 new Figures)