cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Breaking unidirectional invasions jeopardizes biodiversity in spatial May-Leonard systems
Creators: name: Bazeia, D.
name: de Oliveira, B. F.
name: Silva, J. V. O.
name: Szolnoki, A.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Populations and Evolution (q-bio.PE)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Pattern Formation and Solitons (nlin.PS)
subject: Physics and Society (physics.soc-ph)
subject: FOS: Biological sciences
subject: FOS: Physical sciences

description: Non-transitive dominance and the resulting cyclic loop of three or more competing species provide a fundamental mechanism to explain biodiversity in biological and ecological systems. Both Lotka-Volterra and May-Leonard type model approaches agree that heterogeneity of invasion rates within this loop does not hazard the coexistence of competing species. While the resulting abundances of species become heterogeneous, the species who has the smallest invasion power benefits the most from unequal invasions. Nevertheless, the effective invasion rate in a predator and prey interaction can also be modified by breaking the direction of dominance and allowing reversed invasion with a smaller probability. While this alteration has no particular consequence on the behavior within the framework of Lotka-Volterra models, the reactions of May-Leonard systems are highly different. In the latter case, not just the mentioned "survival of the weakest" effect vanishes, but also the coexistence of the loop cannot be maintained if the reversed invasion exceeds a threshold value. Interestingly, the extinction to a uniform state is characterized by a non-monotonous probability function. While the presence of reversed invasion does not fully diminish the evolutionary advantage of the original predator species, but this weakened effective invasion rate helps the related prey species to collect larger initial area for the final battle between them. The competition of these processes determines the likelihood in which uniform state the system terminates.
description: 9 pages, 6 figures
Diversity of Phytophthora Species in Costa Rica's Tropical Forest
Creators: name: Wallace, Sydney F.
Publisher: name: Digital Repository at the University of Maryland
Year: 2015
Subjects: subject: Plant pathology
subject: Multilocus
subject: Oomycete
subject: Phylogeny
subject: Plant Pathogens
subject: Tropics

description: The fungus-like organism Phytophthora includes more than 130 species, most of which are destructive plant pathogens. Information about the occurrence and diversity of Phytophthora species in forest and protected areas are largely unknown. The purpose of this study was to fill in the scientific gap in species biodiversity by conducting a survey in tropical forest ecosystems. The survey was conducted at 10 sites across Costa Rica. Leaves with lesions attached to live plants (LP), fallen from tree canopies (LF), submerged in forest streams (LS) and soil was sampled. Isolate identification was based on a multi-locus (4 mitochondrial and 4 nuclear) phylogeny, and examination of morphological features. In total 258 isolates were characterized into 21 species: eight known and 13 novel species. Phylogenetically, species discovered were placed in seven different clades and clade 9 included the most number of species. Species were more common in transitional forests. The number of unknown species discovered suggests that tropical forests are a “hotspot “for Phytophthora diversity.
Velocity based defrost of evaporator coil of heat pumps
Creators: name: Muthusubramanian, Kamalakkannan
Publisher: name: Digital Repository at the University of Maryland
Year: 2015
Subjects: subject: Mechanical engineering
subject: FOS: Mechanical engineering
subject: Defrost
subject: Forst
subject: Heat Pump

description: Minimization of frost formation on the outdoor coils of residential heat pumps and subsequent defrost cycles to remove the frost in an energy efficient manner remains an active area of research and development in the HVAC industry. Inverting the cycle to reject heat from the outdoor coils is the most common method to run defrost cycles of the residential heat pumps. However, these defrost cycles are energy intensive. This research proposes a novel method that can substantially reduce the energy consumed in such defrost cycles. The method involves controlled use of reverse air flow on the outdoor coil surface during the defrost cycle, resulting in fewer defrost cycles needed for a given duration of heat pump operation. The method further provides better cleaning of the coil surface by improving the draining of the melted frost. It also allows part of the frost to be removed without the need to melt it. In this research, the proposed methods are evaluated experimentally by simulating the frost formation, and defrost cycle in a controlled environment. Defrost cycles were run with two of the most popular control strategies that are in use, time-based defrost and control-based defrost. Experimental results demonstrate that with the use of the proposed method, energy savings of 56% and 31% are possible for the above- and below-freezing environments respectively, as compared to a baseline that represents the ASHRAE recommended operating conditions.
Efficiency in Quantum Key Distribution Protocols with Entangled Gaussian States
Creators: name: Rodó, C.
name: Romero-Isart, O.
name: Eckert, K.
name: Sanpera, A.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Quantum key distribution (QKD) refers to specific quantum strategies which permit the secure distribution of a secret key between two parties that wish to communicate secretly. Quantum cryptography has proven unconditionally secure in ideal scenarios and has been successfully implemented using quantum states with finite (discrete) as well as infinite (continuous) degrees of freedom. Here, we analyze the efficiency of QKD protocols that use as a resource entangled gaussian states and gaussian operations only. In this framework, it has already been shown that QKD is possible (M. Navascués et al. Phys. Rev. Lett. 94, 010502 (2005)) but the issue of its efficiency has not been considered. We propose a figure of merit (the efficiency $E$) to quantify the number of classical correlated bits that can be used to distill a key from a sample of $N$ entangled states. We relate the efficiency of the protocol to the entanglement and purity of the states shared between the parties.
description: 13 pages, 2 figures, OSID style, published version
Gene Expression and Epigenetic Modifications in Stress Response Genes Associated with Teenage and Adult
Creators: name: Hooriyah S Rizavi
Publisher: name: University of Illinois at Chicago
Year: 2021
Subjects: Uncategorized

description: Suicide is a preventable public health issue that accounts for over a million deaths worldwide and is associated with the interaction of several biological, environmental, and neurological factors. Repeatedly, a dysregulated hypothalamic-pituitary-adrenal (HPA) axis has been demonstrated to play a fundamental role and associated with psychiatric disorders and suicide, yet the mechanisms underlying this dysregulation are not clear. Decreased expression of the glucocorticoid receptor (GR) which is highly expressed in the hippocampus and prefrontal cortex (PFC) and is susceptible to epigenetic modulation is a strong indicator of HPA-axis hyperactivity. Additionally, epigenetic mechanisms have been shown to mediate environment x gene interaction through susceptible genes resulting in long-term changes to the genome. One of the most studied epigenetic mark, DNA methylation (DNAm) has been demonstrated to play a major role in various diseases including suicide. The main goal of this thesis was to test the hypothesis that HPA-axis coupled genes are dysregulated in specific areas of the limbic system and that epigenetic reprogramming, in the form of DNAm, maybe a key underlying factor mediating impaired GR signaling. Since there are distinct neurodevelopmental changes occurring during adolescence that may change the endophenotypes of suicide, teenage suicide-completers were studied separately from adult suicide-completers. In teenage suicide-completers, a focused approach was used to identify HPA-axis coupled genes that are differentially expressed and determine significant methylation changes at specific loci of candidate genes. To investigate steady-state DNAm levels, we analyzed DNA methyltransferases (DNMTs), ten-eleven translocation enzymes (TETs), and growth arrest- and DNA-damage-inducible proteins (GADD45) in both PFC and hippocampus. In adult suicide-completers, a hypothesis-free, genome-wide approach was taken to determine DNAm changes specific to neurons in the PFC. Initial bioinformatics reveals novel molecular pathways and networks where epigenetic regulation may be playing a key underlying factor. Together, these findings enhance our understanding of the complex transcriptional regulation of GR gene and also identify key regulators involved in HPA-axis dysregulation. Integrating DNAm and gene expression analysis provides valuable insight into molecular changes and help develop our current knowledge of how epigenetics contributes to alterations in molecular pathways involved in the pathophysiology of suicide.
Fractional periodicity and magnetism of extended quantum rings
Creators: name: Hancock, Y.
name: Suorsa, J.
name: Tölö, E.
name: Harju, A.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: The magnetic properties and nature of the persistent current in small flux-penetrated $t-t'-U$ rings are investigated. An effective rigid-rotator description is formulated for this system, which coincides with a transition to a ferromagnetic state in the model. The criteria for the onset of effective rigid rotation is given. The model is used to understand continuum model ground-state solutions for a 2D few-particle hard-wall quantum dot, where ferromagnetic solutions are found even without the Zeeman coupling to spin. After the onset of effective rigid rotation, a 97--98% correspondence can be determined between the lattice model and continuum model eigenstate results.
Thermo-optic refraction in MoS2 medium for 'Normally On' all Optical switch
Creators: name: Shetty, Pritam P
name: Babu, Mahalingam
name: Maksimov, Dmitrii N
name: Bingi, Jayachandra
Publisher: name: arXiv
Year: 2021
Subjects: subject: Optics (physics.optics)
subject: Applied Physics (physics.app-ph)
subject: FOS: Physical sciences

description: Two dimensional nanomaterials like Molybdenum disulfide have been drawing a lot of interest due to their excellent nonlinear optical response. In this research we study thermal lens formation in MoS2 nanoflakes dispersion using mode mismatched pump probe configuration. Observation of the pump and probe beam intensity patterns gave visual insights on time evolution of photothermal lens formation. Effect of MoS2 nanoflakes concentration on thermo-optic properties of dispersions were studied using thermal lens spectroscopy technique. Further, a thermo-optic refraction based technique to measure thermal lens size is proposed. Thermal lens region size increased with increase in pump power. The observed thermal lens modulation is applied to demonstrate normally on all optical switch which showed excellent modulation of output beam signal by pump beam.
description: 13 pages, 10 figures, Optical Materials Elsevier journal
Discovering Interesting Subgraphs in Social Media Networks
Creators: name: Dasgupta, Subhasis
name: Gupta, Amarnath
Publisher: name: arXiv
Year: 2020
Subjects: subject: Social and Information Networks (cs.SI)
subject: Information Theory (cs.IT)
subject: FOS: Computer and information sciences

description: Social media data are often modeled as heterogeneous graphs with multiple types of nodes and edges. We present a discovery algorithm that first chooses a "background" graph based on a user's analytical interest and then automatically discovers subgraphs that are structurally and content-wise distinctly different from the background graph. The technique combines the notion of a \texttt{group-by} operation on a graph and the notion of subjective interestingness, resulting in an automated discovery of interesting subgraphs. Our experiments on a socio-political database show the effectiveness of our technique.
Gene Expression and Epigenetic Modifications in Stress Response Genes Associated with Teenage and Adult
Creators: name: Hooriyah S Rizavi
Publisher: name: University of Illinois at Chicago
Year: 2020
Subjects: Uncategorized

description: Suicide is a preventable public health issue that accounts for over a million deaths worldwide and is associated with the interaction of several biological, environmental, and neurological factors. Repeatedly, a dysregulated hypothalamic-pituitary-adrenal (HPA) axis has been demonstrated to play a fundamental role and associated with psychiatric disorders and suicide, yet the mechanisms underlying this dysregulation are not clear. Decreased expression of the glucocorticoid receptor (GR) which is highly expressed in the hippocampus and prefrontal cortex (PFC) and is susceptible to epigenetic modulation is a strong indicator of HPA-axis hyperactivity. Additionally, epigenetic mechanisms have been shown to mediate environment x gene interaction through susceptible genes resulting in long-term changes to the genome. One of the most studied epigenetic mark, DNA methylation (DNAm) has been demonstrated to play a major role in various diseases including suicide. The main goal of this thesis was to test the hypothesis that HPA-axis coupled genes are dysregulated in specific areas of the limbic system and that epigenetic reprogramming, in the form of DNAm, maybe a key underlying factor mediating impaired GR signaling. Since there are distinct neurodevelopmental changes occurring during adolescence that may change the endophenotypes of suicide, teenage suicide-completers were studied separately from adult suicide-completers. In teenage suicide-completers, a focused approach was used to identify HPA-axis coupled genes that are differentially expressed and determine significant methylation changes at specific loci of candidate genes. To investigate steady-state DNAm levels, we analyzed DNA methyltransferases (DNMTs), ten-eleven translocation enzymes (TETs), and growth arrest- and DNA-damage-inducible proteins (GADD45) in both PFC and hippocampus. In adult suicide-completers, a hypothesis-free, genome-wide approach was taken to determine DNAm changes specific to neurons in the PFC. Initial bioinformatics reveals novel molecular pathways and networks where epigenetic regulation may be playing a key underlying factor. Together, these findings enhance our understanding of the complex transcriptional regulation of GR gene and also identify key regulators involved in HPA-axis dysregulation. Integrating DNAm and gene expression analysis provides valuable insight into molecular changes and help develop our current knowledge of how epigenetics contributes to alterations in molecular pathways involved in the pathophysiology of suicide.
The Photospheric Temperatures of Betelgeuse during the Great Dimming of 2019/2020: No New Dust Required
Creators: name: Harper, Graham M
name: Guinan, Edward F
name: Wasatonic, Richard
name: Ryde, Nils
Publisher: name: arXiv
Year: 2020
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: The processes that shape the extended atmospheres of red supergiants (RSGs), heat their chromospheres, create molecular reservoirs, drive mass loss, and create dust remain poorly understood. Betelgeuse's V-band "Great Dimming" event of 2019 September /2020 February and its subsequent rapid brightening provides a rare opportunity to study these phenomena. Two different explanations have emerged to explain the dimming; new dust appeared in our line of sight attenuating the photospheric light, or a large portion of the photosphere had cooled. Here we present five years of Wing three-filter (A, B, and C band) TiO and near-IR photometry obtained at the Wasatonic Observatory. These reveal that parts of the photosphere had a mean effective temperature $(T_{\rm eff}$) significantly lower than that found by (Levesque & Massey 2020). Synthetic photometry from MARCS -model photospheres and spectra reveal that the V band, TiO index, and C-band photometry, and previously reported 4000-6800 Angstrom spectra can be quantitatively reproduced if there are multiple photospheric components, as hinted at by VLT-SPHERE images (Montarges et al. 2020). If the cooler component has $ΔT_{\rm eff} \ge 250$ K cooler than 3650 K, then no new dust is required to explain the available empirical constraints. A coincidence of the dominant short- ($\sim 430$ day) and long-period ($\sim 5.8$ yr) V-band variations occurred near the time of deep minimum (Guinan et al. 2019). This is in tandem with the strong correlation of V mag and photospheric radial velocities, recently reported by Dupree et al. (2020b). These suggest that the cooling of a large fraction of the visible star has a dynamic origin related to the photospheric motions, perhaps arising from pulsation or large-scale convective motions.
description: Accepted ApJ - 19 pages, 5 figures
Does the dynamics of sine-Gordon solitons predict active regions of DNA?
Creators: name: Cuenda, Sara
name: Sanchez, Angel
name: Quintero, Niurka R.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Genomics (q-bio.GN)
subject: Mathematical Physics (math-ph)
subject: Pattern Formation and Solitons (nlin.PS)
subject: Quantitative Methods (q-bio.QM)
subject: FOS: Biological sciences
subject: FOS: Physical sciences

description: In this work we analyze the possibility that soliton dynamics in a simple nonlinear model allows functionally relevant predictions of the behaviour of DNA. This suggestion was first put forward by Salerno [Phys. Rev. A, vol. 44, p. 5292 (1991)] by showing results indicating that sine-Gordon kinks were set in motion at certain regions of a DNA sequence that include promoters. We revisit that system and show that the observed behaviour has nothing to do with promoters; on the contrary, it originates from the bases at the boundary, which are not part of the studied genome. We explain this phenomenology in terms of an effective potential for the kink center. This is further extended to disprove recent claims that the dynamics of kinks [Lenholm and Hörnquist, Physica D, vol. 177, p. 233 (2003)] or breathers [Bashford, J. Biol. Phys., vol. 32, p. 27 (2006)] has functional significance. We conclude that no such information can be extracted from this simple nonlinear model or its associated effective potential.
description: 17 pages, 7 figures
Mask-to-Mask Encounters: Performing Disability, Resisting Stigma
Creators: name: Broyer, Nili R.
Publisher: name: University of Illinois at Chicago
Year: 2021
Subjects: Uncategorized

description: Mask-to-Mask Encounters offers a new framework for understanding the intersections between stigma, disability, and performance. It explores how disabled performers — whether in everyday life or representation — deploy creative practices and radical maneuvers that have the potential to contest stigma and escape what I term as “the mask of disgrace.” To a large extent, this dissertation developed as a critical response to and a revision of the sociologist Erving Goffman’s work on stigma, performance of self, and what he termed “face-work.” Based on his work, I conceptualize stigma as a “mask;” as a powerful symbolic negative mediator that interferes with the wearer’ presentation of a “face.” Through disgracing, stigma taints people’s identities and produces disability as inhuman and inferior. As long as disabled people are not accepted as normal human beings, they cannot radically improve their impression and are required to switch to a different set of daily maneuvers that negotiate stigma. Ultimately, I argue that these maneuvers need to be acknowledged as performances.
Finiteness and the falsification by fellow traveler property
Creators: name: Elder, Murray J
Publisher: name: arXiv
Year: 2006
Subjects: subject: Group Theory (math.GR)
subject: FOS: Mathematics
subject: 20F65

description: We prove that groups enjoying the falsification by fellow traveler property are of type $F_3$, and have at most an exponential second order isoperimetric function.
description: Appeared in 2002. I am putting all my past publications on arxiv
First sample of $\rm N_2H^+$ nitrogen isotopic ratio measurements in low-mass protostars
Creators: name: Redaelli, E.
name: Bizzocchi, L.
name: Caselli, P.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Context. The nitrogen isotopic ratio is considered an important diagnostic tool of the star formation process, and $N_2H^+$ is particularly important because it is directly linked to molecular nitrogen $N_2$. However, theoretical models still lack to provide an exhaustive explanation for the observed $^{14}N/^{15}N$ values. Aims. Recent theoretical works suggest that the $^{14}N/^{15}N$ behaviour is dominated by two competing reactions that destroy $ N_2H^+$: dissociative recombination and reaction with CO. When CO is depleted from the gas phase, if $N_2H^+$ recombination rate is lower with respect to the $N^{15}NH^+$ one, the rarer isotopologue is destroyed faster. This implies that the $N_2H^+$ isotopic ratio in protostars should be lower than the one in prestellar cores, and consistent with the elemental value of ~440. We aim to test this hypothesis, producing the first sample of $N_2H^+ / N^{15}NH^+$ measurements in low mass protostars. Methods. We observe the $N_2H^+$ and $N^{15}NH^+$ lowest rotational transition towards six young stellar objects in Perseus and Taurus molecular clouds. We model the spectra with a custom python code using a constant $T_{ex}$ approach to fit the observations. We discuss in appendix the validity of this hypothesis. The derived column densities are used to compute the nitrogen isotopic ratio. Results. Our analysis yields an average of $\rm ^{14}N/^{15}N|_{pro} = 420 \pm 15$ in the protostellar sample. This is consistent with the protosolar value of 440, and significantly lower than the average value previously obtained in a sample of prestellar objects. Conclusions. Our results are in agreement with the hypothesis that, when CO is depleted from the gas-phase, dissociative recombinations with free electrons destroy $N^{15}NH^+$ faster than $N_2H^+$, leading to high isotopic ratios in prestellar cores, where CO is frozen on dust grains.
description: Accepted on A&A on 09 Oct 2020
Cenozoic tectono-thermal evolution of the Weihe Basin, Central China
Creators: name: Lu, Jiafei
name: Rao, Song
name: Hu, Shengbiao
name: Huang, Shunde
name: Zhang, Qiaoran
name: Li, Wenjing
name: Yang, Yinan
Publisher: name: Taylor & Francis
Year: 2024
Subjects: subject: Space Science
subject: Evolutionary Biology
subject: FOS: Biological sciences
subject: Environmental Sciences not elsewhere classified
subject: Chemical Sciences not elsewhere classified
subject: Ecology
subject: Biological Sciences not elsewhere classified
subject: Marine Biology
subject: Plant Biology

description: As a passive rift basin in the Cenozoic, the formation and evolution process of the Weihe Basin has not been well explained. Here we estimate the stretching factor and basal heat flow for each rift period along four geological profiles using a 2D multi-stage finite extension model. The modelling is based on a reconstruction of pre-rift crustal and lithospheric thicknesses, and is calibrated with the current heat flow. The Xi’an Depression had the biggest stretching factor while the Pucheng Uplift had the smallest throughout the Cenozoic period, which saw a range of stretching factors from 1.02 to 2.06. The basal heat flow in the Weihe Basin exhibits a corresponding change. At the end of the Oligocene, Miocene, and Pliocene periods, the basal heat flow varied between 58.5 ~ 64.0 mW·m−2, 59.2 ~ 67.0 mW·m−2, and 59.6 ~ 78.7 mW·m−2, respectively. Increasing stretching factor and basal heat flow indicate that the Weihe Basin is currently in a state of sustained extension. The formation and development of the Weihe Basin are analysed in the context of larger tectonic changes, and it is considered that the Weihe Basin is controlled by pre-existing faults, and formed in a regional tectonic context of sliding and pulling apart first, and tensioning and lifting up later. Since the late Miocene (7.3 Ma), anomalously rapid subsidence has occurred, induced by a new phase of rifting and depth-related lithospheric extension. The thermal genesis of the geothermal system in the Weihe Basin is also thought to be closely related to the latest phase of extension.
Spatio-temporal Modulation Instability of Surface Plasmon Polaritons in Graphene-dielectric Heterostructure
Creators: name: Sharif, Morteza A.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: Using the Jacobi Elliptic Functions, an analytical solution is developed for the nonlinear amplitude equation of Surface Plasmon Polaritons (SPPs) in a graphene-dielectric waveguide. It is shown that the field localization of SPPs coupled with TM polarized terahertz light can be enhanced if the nonlinearity is increased. On the side, a numerical solution based on Split Step Beam Propagation Method (SSBPM) suggests that spatial Modulation Instabilty (MI) can be dominant. Accordingly, larger nonlinearity leads to the generation of discrete plasmon solitons rather than the diffracted profile resulted for the modest nonlinearity. Adding then the temporal variations to the nonlinear amplitude equation and solving numerically by predictor-corrector method, it is revealed that temporal MI appears as ultrashort pulse trains with multi-periodic behavior. Evoking the similarity with a laser cavity, the waveguide can be assumed as a spasing system-assuming the large nonlinearity regime-in which if the coupling depth is raised, the character of MI will be changed from the convective to absolute and the amplitude of SPPs will grow fast. The procedure can be even chaotic and unpredictable. This spasing system is suitable for applications of the electro-optical circuitry, optical amplification, optical communication and biomedical sensing through which the low power consumption and non-destructivity are of important traits.
description: Allowed by Elsevier under the license CC-BY-NC-ND
Banach spaces with projectional skeletons
Creators: name: Kubiś, Wiesław
Publisher: name: arXiv
Year: 2008
Subjects: subject: Functional Analysis (math.FA)
subject: General Topology (math.GN)
subject: FOS: Mathematics
subject: 46B26, 46B03, 46E15, 54C35

description: A projectional skeleton in a Banach space is a sigma-directed family of projections onto separable subspaces, covering the entire space. The class of Banach spaces with projectional skeletons is strictly larger than the class of Plichko spaces (i.e. Banach spaces with a countably norming Markushevich basis). We show that every space with a projectional skeleton has a projectional resolution of the identity and has a norming space with similar properties to Sigma-spaces. We characterize the existence of a projectional skeleton in terms of elementary substructures, providing simple proofs of known results concerning weakly compactly generated spaces and Plichko spaces. We prove a preservation result for Plichko Banach spaces, involving transfinite sequences of projections. As a corollary, we show that a Banach space is Plichko if and only if it has a commutative projectional skeleton.
description: 32 pages (including index and toc); revised (added example, comments, references)
Analyzing Growth Kinematics and Fractal Dimensions of Molybdenum Disulfide Films
Creators: name: Jiang, Yan
name: Baben, Moritz to
name: Lin, Yuankun
name: Littler, Chris
name: Syllaios, A. J.
name: Neogi, Arup
name: Philipose, Usha
Publisher: name: arXiv
Year: 2020
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Chemical Physics (physics.chem-ph)
subject: FOS: Physical sciences

description: Through the positive role of alkali halides in realizing large area growth of transition metal-di-chalcogenide layers has been validated, the film-growth kinematics has not yet been fully established. This work presents a systematic analysis of the MoS$_2$ morphology for films grown under various pre-treatment conditions of the substrate with sodium chloride (NaCl). At an optimum NaCl concentration, the domain size of the monolayer increased by almost two orders of magnitude compared to alkali-free growth of MoS$_2$. The results show an inverse relationship between fractal dimension and areal coverage of the substrate with monolayers and multi-layers, respectively. Using the Fact-Sage software, the role of NaCl in determining the partial pressures of Mo- and S-based compounds in gaseous phase at the growth temperature is elucidated. The presence of alkali salts is shown to affect the domain size and film morphology by affecting the Mo and S partial pressures. Compared to alkali-free synthesis under the same growth conditions, MoS$_2$ film growth assisted by NaCl results in $\approx$ 81$\%$ of the substrate covered by monolayers. Under ideal growth conditions, at an optimum NaCl concentration, nucleation was suppressed, and domains enlarged, resulting in large area growth of MoS$_2$ monolayers. The monolayers were found to be free of unintentional doping with alkali metal and halogen atoms and exhibit high crystallinity and excellent opto-electronic quality.
HEIGHT ESTIMATION AND CONTROL OF A ROTORCRAFT IN GROUND EFFECT USING MULTIPLE PRESSURE PROBES
Creators: name: Hooi, Chin Gian
Publisher: name: Digital Repository at the University of Maryland
Year: 2015
Subjects: subject: Aerospace engineering
subject: Robotics
subject: Bayesian Filter
subject: Flow-based height estimation
subject: Multi-component pressure probes
subject: Observer-based Feedback Control
subject: Rotorcraft Landing in Ground Effect
subject: Rotorcraft Shipboard Landing

description: This thesis describes a dynamic height estimator and controller for rotorcraft landing and hovering in ground effect based on flowfield sensing and modeling. The rotor downwash in ground effect is represented using a ring-source potential flow model selected for real-time use. Experimental verification of the flow model and an augmented flow model for tilt are presented. A nonlinear dynamic model of a compound pendulum heave test stand that reduces to the dynamics of a rotorcraft in ground effect is presented with open-loop analysis and closed-loop control simulation. Equations of motion and stability characterization of of a heaving rotor IGE are derived for external perturbations and it is shown that a uniform sideward wind does not cause instability and uniform axial wind from the top can cause instability. Flowfield velocity measurements are assimilated into a grid-based recursive Bayesian filter to estimate height above ground in both simulation and experiment. Height tracking in ground effect and landing using the estimated height are implemented with a dynamic linear controller in both simulation and experiment. Mean estimation and motion errors are found to be no greater than 5% and 9% respectively, demonstrating that height estimation and control is possible with only flow sensing and modeling.
Top 10 U.S. Municipal Police Departments and Their Social Media Usage
Creators: name: Brainard, Lori
name: Edlins, Mariglynn
Publisher: name: Maryland Shared Open Access Repository
Year: 2014
Subjects: community policing, social media, civic engagement

description: Social media technologies present a new way for government agencies to connect with, and potentially collaborate with, their residents. Police departments (PDs) are a setting ripe for use of social media as an extension of their community policing efforts. In this article, we explore the use of social media by PDs in the top 10 most populous U.S. cities. We analyze police-initiated posts on Facebook, Twitter, and YouTube over a 3-month period to determine what accounts PDs use, if they use social media for information transmission or interaction, and if they use the accounts for dialogue that might make collaboration possible. We find that while PDs have and use social media, and while citizens are responsive, there is much less interaction in part due to nonresponsiveness of PDs themselves. We thus conclude that though the existence of some PD-resident dialogue is promising, very little was collaborative.
Magellanic Mayhem: Metallicities and Motions
Creators: name: Grady, J.
name: Belokurov, V.
name: Evans, N. W.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We assemble a catalogue of Magellanic Cloud red giants from Data Release 2 of the $Gaia$ mission and, utilising machine learning methods, obtain photometric metallicity estimates for them. In doing so, we are able to chemically map the entirety of the Magellanic System at once. Our high resolution maps reveal a plethora of substructure, with the Large Magellanic Cloud (LMC) bar and spiral arm being readily apparent. We uncover a curious spiral-like feature in the southern portion of the LMC disc, hosting relatively metal-rich giants and likely a by-product of historic encounter with the Small Magellanic Cloud (SMC). Modelling the LMC as an inclined thin disc, we find a shallow metallicity gradient of $-0.048 \pm 0.001$ dex/kpc out to $\sim 12^{\circ}$ from the centre of the dwarf. We see evidence that the Small Magellanic Cloud is disrupting, with its outer iso-density contours displaying the S-shape symptomatic of tidal stripping. On studying the proper motions of the SMC giants, we observe a population of them being violently dragged towards the larger Cloud. The perturbed stars predominately lie in front of the SMC, and we interpret that they exist as a tidal tail of the dwarf, trailing in its motion and undergoing severe disruption from the LMC. We find the metallicity structure in the Magellanic Bridge region to be complex, with evidence for a composite nature in this stellar population, consisting of both LMC and SMC debris.
description: MNRAS, submitted
Empiricism and Exchange: Dutch-Japanese Relations Through Material Culture, 1600-1750
Creators: name: Jamrisko, Kristi
Publisher: name: Digital Repository at the University of Maryland
Year: 2015
Subjects: subject: Art history
subject: International relations
subject: Science history
subject: Dutch
subject: Dutch East India Company
subject: empiricism
subject: international relations
subject: Japan
subject: material culture

description: This thesis will focus on unique modes of material culture exchange to shed light on the early relationship between the Dutch Republic and Japan in the seventeenth and early eighteenth centuries. I will demonstrate that while exoticism and “otherness” animated this cross-cultural interaction, important commonalities between the two countries also merit examination. The rich and diverse material culture bequeathed by the Dutch-Japanese relationship, particularly when viewed in the context of “micro-exchanges” such as gift-giving and (anti-) religious ritual, offers an excellent means for exploring these similarities. Three case studies – the Japonsche rok (Japanese robe), Rembert Dodoens’s Cruydt-Boeck (Herbal), and bas-relief plaques of Christ and the Virgin Mary, which in Japan were transformed into fumi-e (踏み絵, “trampling images”) – will illuminate one of these commonalities: the simultaneous rise of empiricism in both the Dutch Republic and Japan.
Disturbed isolated galaxies: indicators of a dark galaxy population?
Creators: name: Karachentsev, I. D.
name: Karachentseva, V. E.
name: Huchtmeier, W. K.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We report the results of our search for disturbed (interacting) objects among very isolated galaxies. The inspections of 1050 northern isolated galaxies from KIG and 500 nearby, very isolated galaxies situated in the Local Supercluster yielded five and four strongly disturbed galaxies, respectively. We suggest that the existence of "dark" galaxies explains the observed signs of interaction. This assumption leads to a cosmic abundance of dark galaxies (with the typical masses for luminous galaxies) that is less than ~1/20 the population of visible galaxies.
description: 5 pages, 1 figure. Astronomy and Astrophysics, accepted
A Metaheuristic-Driven Approach to Fine-Tune Deep Boltzmann Machines
Creators: name: Passos, Leandro Aparecido
name: Papa, João Paulo
Publisher: name: arXiv
Year: 2021
Subjects: subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: Deep learning techniques, such as Deep Boltzmann Machines (DBMs), have received considerable attention over the past years due to the outstanding results concerning a variable range of domains. One of the main shortcomings of these techniques involves the choice of their hyperparameters, since they have a significant impact on the final results. This work addresses the issue of fine-tuning hyperparameters of Deep Boltzmann Machines using metaheuristic optimization techniques with different backgrounds, such as swarm intelligence, memory- and evolutionary-based approaches. Experiments conducted in three public datasets for binary image reconstruction showed that metaheuristic techniques can obtain reasonable results.
description: 30 pages, 7 figures
Interferometer Euro-Asian Network: Detection Characteristics for Signals of Known Shape
Creators: name: Rudenko, V.
name: Andrusenko, S.
name: Krichevskiy, D.
name: Manucharyan, G.
Publisher: name: arXiv
Year: 2020
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: In this paper, we estimate efficiency of a conceivable Euro-Asian network of gravitational wave (GW) interferometers that might be realized having in mind a plan of construction of third generation interferometer in Novosibirsk region. Subsequently, some network would be composed, including four GW detectors. Among them there are the already active interferometers VIRGO (Italy) and KAGRA (Japan), Indian interferometer under construction - LIGO India and the interferometer in Siberia mentioned above. The quality of network in question is considered on the base of typical numerical criteria of efficiency for detecting GW signals of known structure - radiation of relativistic binary coalescence.
description: 19 pages, 7 figures
Women’s needs and housing in urban China: the gender impacts of reform and redevelpoment (a case study of Jinhua Street, Guangzhou)
Creators: name: Harrison, Averil Judith
Publisher: name: University of British Columbia
Year: 2009

description: This study presents a qualitative impression on the gender related implications of the changing housing environment in urban China. China's housing allocation system is changing from a socialist method of subsidized housing allocation to one of free market sales. Inner city neighbourhoods are also physically changing under extensive neighbourhood redevelopment programs. The findings are based on a case study of a neighbourhood in Guangzhou (Canton), which is currently undergoing urban renewal and housing reforms. Thirty-eight women, representing a wide spectrum of age (22-81), marital status, occupation and housing conditions were interviewed. The thesis examines women's housing needs according to Caroline Moser's classification of practical gender needs and strategic gender needs. Physical changes to housing such as reasonable sized apartments and access to elevators are identified as practical gender needs. The traditional housing allocation system also requires reform in order to address the practical gender needs of convenient home work journeys and access to child care facilities. The first strategic gender need identified is breaking the traditional patrilocal living arrangement. This form of family living arrangement subordinates women to her mother-in-law and husband and limits her role in family decision making. The second strategic interest involves changing the process by which housing is allocated. Traditional patterns of allocation are biased in favour of men and are a barrier to accessibility for single and divorced women. The findings of the study suggest that Chinese women must rely on men to access housing. Young women's choice of spouse and time of marriage is related to housing. Housing options are limited for women who choose not to marry. Divorced women are severely disadvantaged. Women are generally supportive of housing reforms and redevelopment programs but feel that they are unable to address the specific housing problems faced by women.
Thermal noise and mechanical loss of SiO$_2$/Ta$_2$O$_5$ optical coatings at cryogenic temperatures
Creators: name: Robinson, John M
name: Oelker, Eric
name: Milner, William R
name: Kedar, Dhruv
name: Zhang, Wei
name: Legero, Thomas
name: Matei, Dan G
name: Hafner, Sebastian
name: Riehle, Fritz
name: Sterr, Uwe
name: Ye, Jun
Publisher: name: arXiv
Year: 2020
Subjects: subject: Instrumentation and Detectors (physics.ins-det)
subject: Atomic Physics (physics.atom-ph)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: Mechanical loss of dielectric mirror coatings sets fundamental limits for both gravitational wave detectors and cavity-stabilized optical local oscillators for atomic clocks. Two approaches are used to determine the mechanical loss: ringdown measurements of the coating quality factor and direct measurement of the coating thermal noise. Here we report a systematic study of the mirror thermal noise from room temperature to 4 K by operating reference cavities at these temperatures. The directly measured thermal noise is used to extract the corresponding mechanical loss for SiO$_2$/Ta$_2$O$_5$ coatings, which are compared with previously reported values.
Exchange interaction between single magnetic adatoms
Creators: name: Wahl, P.
name: Simon, P.
name: Diekhoener, L.
name: Stepanyuk, V. S.
name: Bruno, P.
name: Schneider, M. A.
name: Kern, K.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: The magnetic coupling between single Co atoms adsorbed on a copper surface is determined by probing the Kondo resonance using low-temperature scanning tunneling spectroscopy. The Kondo resonance, which is due to magnetic correlation effects between the spin of a magnetic adatom and the conduction electrons of the substrate, is modified in a characteristic way by the coupling of the neighbouring adatom spins. Increasing the interatomic distance of a Cobalt dimer from 2.56A to 8.1A we follow the oscillatory transition from ferromagnetic to antiferromagnetic coupling. Adding a third atom to the antiferromagnetically coupled dimer results in the formation of a collective correlated state.
description: 4 pages, 2 figures, 1 table
Kaon-condensed hypernuclei as highly dense self-bound objects
Creators: name: Muto, Takumi
Publisher: name: arXiv
Year: 2008
Subjects: subject: Nuclear Theory (nucl-th)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: The structure of $K^-$-condensed hypernuclei, which may be produced in the laboratory in strangeness-conserving processes, is investigated using an effective chiral Lagrangian for the kaon-baryon interaction, combined with a nonrelativistic baryon-baryon interaction model. It is shown that a large number of negative strangeness is needed for the formation of highly dense and deeply bound state with kaon condensates and that part of the strangeness should be carried by hyperons mixed in the nucleus. The properties of kaon-condensed hypernuclei such as the ground state energy and particle composition are discussed. Such a self-bound object has a long lifetime and may decay only through weak interaction processes. Comparison with other possible nuclear states is also made, such as kaon-condensed nuclei without mixing of hyperons and noncondensed multistrange hypernuclei. Implications of kaon-condensed hypernuclei for experiments are mentioned.
description: 30 pages, 10 figures
How to hide a secret direction
Creators: name: Bagan, E.
name: Calsamiglia, J.
name: Demkowicz-Dobrzanski, R.
name: Munoz-Tapia, R.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We present a procedure to share a secret spatial direction in the absence of a common reference frame using a multipartite quantum state. The procedure guarantees that the parties can determine the direction if they perform joint measurements on the state, but fail to do so if they restrict themselves to local operations and classical communication (LOCC). We calculate the fidelity for joint measurements, give bounds on the fidelity achievable by LOCC, and prove that there is a non-vanishing gap between the two of them, even in the limit of infinitely many copies. The robustness of the procedure under particle loss is also studied. As a by-product we find bounds on the probability of discriminating by LOCC between the invariant subspaces of total angular momentum N/2 and N/2-1 in a system of N elementary spins.
description: 4 pages, 1 figure
Numerical heating in particle-in-cell simulations with Monte Carlo binary collisions
Creators: name: Alves, E. Paulo
name: Mori, Warren B.
name: Fiuza, Frederico
Publisher: name: arXiv
Year: 2021
Subjects: subject: Plasma Physics (physics.plasm-ph)
subject: Computational Physics (physics.comp-ph)
subject: FOS: Physical sciences

description: The binary Monte Carlo (MC) collision algorithm is a standard and robust method to include binary Coulomb collision effects in particle-in-cell (PIC) simulations of plasmas. Here, we show that the coupling between PIC and MC algorithms can give rise to (nonphysical) numerical heating of the system, that significantly exceeds that observed when these algorithms operate independently. We argue that this deleterious effect results from an inconsistency between the particle motion associated with MC-collisions and the work performed by the collective electromagnetic field on the PIC grid. This inconsistency manifests as the (artificial) stochastic production of electromagnetic energy, which ultimately heats the plasma particles. The MC-induced numerical heating can significantly impact the evolution of the simulated system for long simulation times ($\gtrsim 10^3$ collision periods, for typical numerical parameters). We describe the source of the MC-induced numerical heating analytically and discuss strategies to minimize it.