cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Exciton storage in CdSe/CdS tetrapod semiconductor nanocrystals: Electric field effects on exciton and multiexciton states
Creators: name: Liu, Sue
name: Borys, Nicholas J.
name: Huang, Jing
name: Talapin, Dmitri V.
name: Lupton, John M.
Publisher: name: Universität Regensburg
Year: 2012
Subjects: subject: QUANTUM DOTS; PHOTOLUMINESCENCE INTENSITY; DYNAMICS; RECOMBINATION; EMISSION; FLUORESCENCE; CHARGE; AUGER; WELL; SPIN
subject: 530 Physik
subject: 73.22.-f
subject: 73.50.Gr
subject: 73.63.Bd
subject: 78.47.D-

description: CdSe/CdS nanocrystal tetrapods are interesting building blocks for excitonic circuits, where the flow of excitation energy is gated by an external stimulus. The physical morphology of the nanoparticle, along with the electronic structure, which favors electron delocalization between the two semiconductors, suggests that all orientations of a particle relative to an external electric field will allow for excitons to be dissociated, stored, and released at a later time. While this approach, in principle, works, and fluorescence quenching of over 95% can be achieved electrically, we find that discrete trap states within the CdS are required to dissociate and store the exciton. These states are rapidly filled up with increasing excitation density, leading to a dramatic reduction in quenching efficiency. Charge separation is not instantaneous on the CdS excitonic antennae in which light absorption occurs, but arises from the relaxed exciton following hole localization in the core. Consequently, whereas strong electromodulation of the core exciton is observed, the core multiexciton and the CdS arm exciton are not affected by an external electric field.
HERMES: a high-resolution fibre-fed spectrograph for the Mercator telescope
Creators: name: Raskin, Gert
name: Van Winckel, Hans
name: Hensberge, Herman
name: Jorissen, Alain
name: Lehmann, Holger
name: Waelkens, Christoffel
name: Avila, Gerardo
name: De Cuyper, Jean-Pierre
name: Degroote, Pieter
name: Dubosson, Rene
name: Dumortier, Louis
name: Fremat, Yves
name: Laux, Uwe
name: Michaud, Bernard
name: Morren, Johan
name: Padilla, Jesus Perez
name: Pessemier, Wim
name: Prins, Saskia
name: Smolders, Kristof
name: Van Eck, Sophie
name: Winkler, Johannes
Publisher: name: arXiv
Year: 2010
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: The HERMES high-resolution spectrograph project aims at exploiting the specific potential of small but flexible telescopes in observational astrophysics. The optimised optical design of the spectrograph is based on the well-proven concept of white-pupil beam folding for high-resolution spectroscopy. In this contribution we present the complete project, including the spectrograph design and procurement details, the telescope adaptor and calibration unit, the detector system, as well as the optimised data-reduction pipeline. We present a detailed performance analysis to show that the spectrograph performs as specified both in optical quality and in total efficiency. With a spectral resolution of 85000 (63000 for the low-resolution fibre), a spectral coverage from 377 to 900nm in a single exposure and a peak efficiency of 28%, HERMES proves to be an ideal instrument for building up time series of high-quality data of variable (stellar) phenomena.
description: 13 pages
THE MAIN PROBLEMS THAT ARISE IN THE EXTRACTION OF RAW MATERIALS IN LIMESTONE QUARRIES
Creators: name: Otepov, Polat
Publisher: name: Zenodo
Year: 2024

description: When assessing the strength of slag-alkaline binder based on crushing waste, rational proportions of components were revealed. It was found that the samples have a dense and homogeneous structure after hardening. The average compressive strength reaches 41.2 MPa. The results of testing samples from a dry building mixture including slag-alkaline binder with quartz sand are presented. The limits of compressive and bending strength of samples are determined. Diagrams of strength changes depending on the composition of the mixture and changes in the water-binder ratio are given.
Pichi
Creators: name: Yakpo, Kofi
Publisher: name: Zenodo
Year: 2013
Subjects: Creole
Pidgin
Language description
Language documentation
APiCS
Atlas of Pidgin and Creole Language Structures
English
English-lexifier creole
Spanish
Language contact

description: This is the survey chapter on the English-lexifier Creole Pichi (Bioko, Equatorial Guinea) for the Atlas of Pidgin and Creole Language Structures (APiCS).
description: Online version of this chapter can be accessed at: https://apics-online.info/surveys/19. The language structure data set can be accessed at: https://apics-online.info/contributions/19.
On the edge : a spatial and temporal analysis of genetic variation for endangered, peripheral American badger populations
Creators: name: Ford, Brett
Publisher: name: University of British Columbia
Year: 2017

description: Peripheral populations are often characterized by small population size and low genetic diversity, with many at risk of extirpation. Threats to these populations may be even more pronounced in human-modified landscapes and areas of recent recolonization, that further reduce resiliency to environmental change. The western American badger (Taxidea taxus jeffersonii) is an endangered mammal in Canada inhabiting the sparse grasslands of south-central British Columbia (BC). In addition to being situated at the northwestern edge of the species’ range, recent human development and vehicle-induced mortalities have limited population recovery, causing unknown consequences on the genetic variation of these peripheral populations. By collecting mitochondrial haplotypic data and microsatellite genotypic data from roughly 300 samples in BC and neighboring regions, we assess how geographical isolation, anthropogenic disturbance, and glaciation history have shaped the genetic structure of peripheral American badger populations in this region. We discovered that the genetic structure of BC American badger populations epitomizes expectations for peripheral populations, with low levels of genetic diversity, significant differentiation, and population genetic structure all intensifying with an increase in marginality. We find evidence that these patterns, which vastly contrast those observed in central populations, are likely being influenced by geographical and anthropogenic features, that were both significantly correlated with genetic distance between individuals in western BC. Roadways were identified as potential barriers to gene flow across various scales and analyses. We also provide evidence for several glacial refugia impacting population genetic structure across the American badger range, two of which may have existed in British Columbia and the greater Pacific Northwest. Taken together, our study suggests that American badgers in British Columbia exemplify dynamics of peripheral populations, with genetic variation shaped by a unique glacial history and atypical landscape matrix, vastly contrasting central populations. Mitigating the impact of anthropogenic barriers as well as increasing connectivity between populations in BC and with populations in the United States will be essential for conserving the distinct genetic diversity of this endangered species.
Loops with exponent three in all isotopes
Creators: name: Kinyon, Michael
name: Wanless, Ian M.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Group Theory (math.GR)
subject: Combinatorics (math.CO)
subject: FOS: Mathematics
subject: 20N05, 05B15

description: It was shown by van Rees \cite{vR} that a latin square of order $n$ has at most $n^2(n-1)/18$ latin subsquares of order $3$. He conjectured that this bound is only achieved if $n$ is a power of $3$. We show that it can only be achieved if $n\equiv3\bmod6$. We also state several conditions that are equivalent to achieving the van Rees bound. One of these is that the Cayley table of a loop achieves the van Rees bound if and only if every loop isotope has exponent $3$. We call such loops \emph{van Rees loops} and show that they form an equationally defined variety. We also show that (1) In a van Rees loop, any subloop of index 3 is normal, (2) There are exactly 6 nonassociative van Rees loops of order $27$ with a non-trivial nucleus and at least 1 with all nuclei trivial, (3) Every commutative van Rees loop has the weak inverse property and (4) For each van Rees loop there is an associated family of Steiner quasigroups.
description: Revived, revised and resubmitted
The generalized Kupershmidt deformation for constructing new integrable systems from integrable bi-Hamiltonian systems
Creators: name: Yao, Yuqin
name: Zeng, Yunbo
Publisher: name: arXiv
Year: 2010
Subjects: subject: Exactly Solvable and Integrable Systems (nlin.SI)
subject: FOS: Physical sciences

description: Based on the Kupershmidt deformation for any integrable bi-Hamiltonian systems presented in [4], we propose the generalized Kupershmidt deformation to construct new systems from integrable bi-Hamiltonian systems, which provides a nonholonomic perturbation of the bi-Hamiltonian systems. The generalized Kupershmidt deformation is conjectured to preserve integrability. The conjecture is verified in a few representative cases: KdV equation, Boussinesq equation, Jaulent-Miodek equation and Camassa-Holm equation. For these specific cases, we present a general procedure to convert the generalized Kupershmidt deformation into the integrable Rosochatius deformation of soliton equation with self-consistent sources, then to transform it into a $t$-type bi-Hamiltonian system. By using this generalized Kupershmidt deformation some new integrable systems are derived. In fact, this generalized Kupershmidt deformation also provides a new method to construct the integrable Rosochatius deformation of soliton equation with self-consistent sources.
description: 21 pages, to appear in Journal of Mathematical Physics
Lorentz-violating effects in the Bose-Einstein condensation of an ideal bosonic gas
Creators: name: Casana, Rodolfo
name: da Silva, Kleber A. T.
Publisher: name: arXiv
Year: 2011
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Quantum Gases (cond-mat.quant-gas)
subject: FOS: Physical sciences

description: We have studied the effects of Lorentz-violation in the Bose-Einstein condensation (BEC) of an ideal boson gas, by assessing both the nonrelativistic and ultrarelativistic limits. Our model describes a massive complex scalar field coupled to a CPT-even and Lorentz-violating background. We irst analyze the nonrelativistic case, at this level by using experimental data, we obtain upper-bounds for some LIV parameters. In the sequel, we have constructed the partition function for the relativistic ideal boson gas which to be able of a consistent description requires the imposition of severe restrictions on some LIV coefficients. In both cases, we have demonstrated that the LIV contributions are contained in an overall factor, which multiplies almost all thermodynamical properties. An exception is the fraction of the condensed particles.
description: 7 pages Latex2e. To be published in Modern Physics Letters A
An expression for the Homflypt polynomial and some applications
Creators: name: Emmes, David
Publisher: name: arXiv
Year: 2010
Subjects: subject: Geometric Topology (math.GT)
subject: FOS: Mathematics
subject: 57M25, 57M27

description: Associated with each oriented link is the two variable Homflypt polynomial. The Morton-Franks-Williams (MFW) inequality gives rise to an expression for the Homflypt polynomial with MFW coefficient polynomials. These MFW coefficient polynomials are labelled in a braid-dependent manner and may be zero, but display a number of interesting relations. One consequence is an expression for the first three Laurent coefficient polynomials in z as a function of the other coefficient polynomials and three link invariants: the minimum v-degree and v-span of the Homflypt polynomial, and the Conway polynomial. These expressions are used to derive additional properties of the Homflypt polynomial for general n-braid links. One specific result is that the Jones and Homflypt polynomials distinguish the same three-braid links.
description: 20 pages; this version was rewritten for readability, expands the prior results, and removes a result for 3-braids whose proof was flawed (prop. 2.8 on monotonic properties). This version is the unrevised version accepted for publication, so the theorem, equation, etc. numbering differs from the published version due to those further revisions
The influence of temporal coherence on the dynamical Casimir effect
Creators: name: Mendonca, J. T.
name: Brodin, G.
name: Marklund, M.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We study the dynamical Casimir effect in the presence of a finite coherence time, which is associated with a finite quality factor of the optical cavity. We use the time refraction model, where a fixed cavity with a modulated optical medium, replaces the empty cavity with a vibrating mirror. Temporal coherence is described with the help of cavity quasi-mode operators. Asymptotic expressions for the number of photon pairs generated from vacuum are derived.
description: 8 pages, 1 figure
Dynamics of a stored Zeeman coherence grating in an external magnetic field
Creators: name: Moretti, D.
name: Felinto, D.
name: Tabosa, J. W. R.
name: Lezama, A.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We investigate the evolution of a Zeeman coherence grating induced in a cold atomic cesium sample in the presence of an external magnetic field. The gratings are created in a three-beam light storage configuration using two quasi-collinear writing laser pulses and reading with a counterpropagating pulse after a variable time delay. The phase conjugated pulse arising from the atomic sample is monitored. Collapses and revivals of the retrieved pulse are observed for different polarizations of the laser beams and for different directions of the applied magnetic field. While magnetic field inhomogeneities are responsible for the decay of the coherent atomic response, a five-fold increase in the coherence decay time, with respect to no applied magnetic field, is obtained for an appropriate choice of the direction of the applied magnetic field. A simplified theoretical model illustrates the role of the magnetic field mean and its inhomogeneity on the collective atomic response.
description: To appear in J. Phys. B
Towards the Classification of Weak Fano Threefolds with ρ= 2
Creators: name: Cutrone, Joseph W.
name: Marshburn, Nicholas A.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Algebraic Geometry (math.AG)
subject: FOS: Mathematics

description: In this paper, we provide examples of Sarkisov links of type II between complex projective Fano threefolds $X$ with $ρ(X) = 1$. To show examples of these links, we study smooth weak Fano threefolds with extremal rays of type $E$. We further assume that the pluri-anticanonical morphism contracts only a finite number of curves. We numerically classify smooth weak Fano threefolds with $ρ(X) = 2$ having an extremal ray of type $E$ both before and after a flop as well as prove the existence of some of these numerical cases.
description: 36 pages, updated 1/6/2014
Stability and instability of Navier boundary layers
Creators: name: Paddick, Matthew
Publisher: name: arXiv
Year: 2011
Subjects: subject: Analysis of PDEs (math.AP)
subject: FOS: Mathematics
subject: 35Q30, 35Q31, 76D05, 76D10

description: We study the inviscid limit problem for the incompressible Navier-Stokes equation on a half-plane with a Navier boundary condition depending on the viscosity. On one hand, we prove the $L^2$ convergence of Leray solutions to the solution of the Euler equation. On the other hand, we show the nonlinear instability of WKB expansions in the stronger $L^{\infty}$ and $\dot{H}^s$ (s>1) norms.
Multi-method approach to quantifying nutrient retention in a wastewater irrigated watershed.
Creators: name: Friesen, Anthony M
Publisher: name: University of British Columbia
Year: 2017

description: As water is becoming more scarce, the application of wastewater onto land is becoming increasingly common. It is of particular interest in places where the otherwise receiving water body is considered too sensitive to handle the increased load of nutrients, and other wastewater constituents. This study utilized three methods to determine the extent to which phosphorus and nitrogen are being retained within a wastewater irrigated watershed in southern B.C., Canada. The methods include; Mass Balance, an End Member Mixing Analysis (EMMA) to determine real time and seasonal retention, and a soil analysis to determine long term retention within the soil profile. Retention estimates of P and N using the mass balance method were found to be between 53-93% and 48-77% respectively. Using the End Member Mixing Analysis, retention rates of P and N were found to be between 72-91% and 64-81% respectively. Seasonally, summer and winter had the highest retention rates, while the lowest retention was found during spring freshet. The soil analysis results found a 32% increase in phosphorus storage in irrigated soil over non-irrigated soils. This increase translated to a 40% retention rate (11,300 kg) of phosphorus in the irrigated soils during the course of the 35-year irrigation program.
Hyperincursive Cogitata and Incursive Cogitantes: Scholarly Discourse as a Strongly Anticipatory System
Creators: name: Leydesdorff, Loet
Publisher: name: arXiv
Year: 2011
Subjects: subject: Digital Libraries (cs.DL)
subject: FOS: Computer and information sciences

description: Strongly anticipatory systems-that is, systems which use models of themselves for their further development-and which additionally may be able to run hyperincursive routines-that is, develop only with reference to their future states-cannot exist in res extensa, but can only be envisaged in res cogitans. One needs incursive routines in cogitantes to instantiate these systems. Unlike historical systems (with recursion), these hyper-incursive routines generate redundancies by opening horizons of other possible states. Thus, intentional systems can enrich our perceptions of the cases that have happened to occur. The perspective of hindsight codified at the above-individual level enables us furthermore to intervene technologically. The theory and computation of anticipatory systems have made these loops between supra-individual hyper-incursion, individual incursion (in instantiation), and historical recursion accessible for modeling and empirical investigation.
description: arXiv admin note: substantial text overlap with arXiv:1011.3244
The Neuropeptide Y Y1 receptor: a diagnostic marker? Expression in MCF-7 breast cancer cells is down-regulated by antiestrogens in vitro and in xenografts
Creators: name: Memminger, Martin
name: Keller, Max
name: Lopuch, Miroslaw
name: Pop, Nathalie
name: Bernhardt, Günther
name: von Angerer, Erwin
name: Buschauer, Armin
Publisher: name: Universität Regensburg
Year: 2012
Subjects: subject: neuropeptide Y; Y1 receptor; G-protein coupled receptor; estrogen receptor; imaging; MCF-7 breast cancer; xenograft; nude mice; autoradiography; radioligand; [3H]-UR-MK114; argininamides; antiestrogen; tamoxifen; diagnostic marker
subject: 540 Chemie
subject: 570 Biowissenschaften, Biologie
subject: 615 Pharmazie

description: The neuropeptide Y (NPY) Y1 receptor (Y1R) has been suggested as a tumor marker for in vivo imaging and as a therapeutic target. In view of the assumed link between estrogen receptor (ER) and Y1R in mammary carcinoma and with respect to the development of new diagnostic tools we investigated the Y1R protein expression in human MCF-7 cell variants differing in ER content and sensitivity against antiestrogens. ER and Y1R expression were quantified by radioligand binding using [3H]-17beta-estradiol and the Y1R selective antagonist [3H]-UR-MK114, respectively. The latter was used for cellular binding studies and for autoradiography of MCF-7 xenografts. The fluorescent ligands Cy5-pNPY (universal Y1R, Y2R and Y5R agonist) and UR-MK22 (selective Y1R antagonist), as well as the selective antagonists BIBP3226 (Y1R), BIIE0246 (Y2R) and CGP71683 (Y5R) were used to identify the NPY receptor subtype(s) by confocal microscopy. Y1R functionality was determined by mobilization of intracellular Ca2+. Sensitivity of MCF-7 cells against antiestrogen 4-hydroxytamoxifen correlated directly with the ER content. The exclusive expression of Y1Rs was confirmed by confocal microscopy. The Y1R protein was up-regulated (100 %) by 17beta-estradiol (EC50 20 pM) and the predominant role of ERalpha was demonstrated by using the ERalpha-selective agonist “propylpyrazole triol”. 17beta-Estradiol-induced over-expression of functional Y1R protein was reverted by the antiestrogen fulvestrant (IC50 5 nM) in vitro. Furthermore, tamoxifen treatment of nude mice resulted in an almost total loss of Y1Rs in MCF-7 xenografts. In conclusion, the value of the Y1R as a target for therapy and imaging in breast cancer patients may be compromised due to Y1R down-regulation induced by hormonal (antiestrogen) treatment.
A description of the f2(1270), rho3(1690), f4(2050), rho5(2350) and f6(2510) resonances as multi-rho(770) states
Creators: name: Roca, L.
name: Oset, E.
Publisher: name: arXiv
Year: 2010
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: In a previous work regarding the interaction of two $ρ(770)$ resonances, the $f_2(1270)$ ($J^{PC}=2^{++}$) resonance was obtained dynamically as a two-$ρ$ molecule with a very strong binding energy, 135~MeV per $ρ$ particle. In the present work we use the $ρρ$ interaction in spin 2 and isospin 0 channel to show that the resonances $ρ_3(1690)$ ($3^{--}$), $f_4(2050)$ ($4^{++}$), $ρ_5(2350)$ ($5^{--}$) and $f_6(2510)$ ($6^{++}$) are basically molecules of increasing number of $ρ(770)$ particles. We use the fixed center approximation of the Faddeev equations to write the multi-body interaction in terms of the two-body scattering amplitudes. We find the masses of the states very close to the experimental values and we get an increasing value of the binding energy per $ρ$ as the number of $ρ$ mesons is increased.
description: 17 pages, 6 figures
Long-term human-environment interaction on dynamic coastal landscapes : examples from 15,000 years of shoreline and settlement change in the Prince Rupert Harbour area
Creators: name: Letham, Bryn
Publisher: name: University of British Columbia
Year: 2017

description: This dissertation explores the intersections of past human settlement and the dynamism of coastal landscapes in the Prince Rupert Harbour area, in Tsimshian territory on the northern Northwest Coast, British Columbia. Taking relative sea level (RSL) and shoreline change as a major physical force in coastal people’s lives, both past and present, I explore how coastal fisher-hunter-gatherers occupied this transforming landscape and ultimately consider ways in which people’s engagement with the shores they lived upon may have been generative of new relationships to place and people. A reconstruction of the history of RSL change over the last 15,000 years is developed and presented. This is used to design a predictive model for landforms ideal for human habitation associated with raised paleoshorelines. A field survey of several of these targets identified three archaeological sites dating between 9500 and 6000 BP, pushing the archaeologically-recorded occupation of the area back 3000 years. These early Holocene sites indicate persistent use of places into the later Holocene as shoreline positions shifted with regressing RSL; it is proposed that this is associated with notions of territorial proprietorship acquired through historical precedence of use. The second half of the dissertation presents a study of the developmental history of several large late Holocene village sites associated with massive anthropogenic shell-bearing components. It is argued that these sites themselves are significant anthropogenic transformations to shorelines, and it is demonstrated that there are instances where shell was very rapidly accumulated to raise, extend, or level landforms, and likely to buffer against foreshore erosion. I contend that many of the landscapes of the Northwest Coast are ‘fisher-hunter-gatherer built environments’, and argue that increased physical investments in modifying coastlines may be associated with a transformation in the way territorial proprietorship is conceived. Specifically, I suggest it is associated with the formalization of institutionalized proprietorship systems similar to the rigid systems observed ethnographically for the Tsimshian, and that this may have resulted from the arrival of large numbers of newcomers to the region over the last 3000 years. The institutionalization of systems governing access to territory and resources enhanced social inequalities.
Fitting birth-death processes to panel data with applications to bacterial DNA fingerprinting
Creators: name: Doss, Charles R.
name: Suchard, Marc A.
name: Holmes, Ian
name: Kato-Maeda, Midori
name: Minin, Vladimir N.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Computation (stat.CO)
subject: Populations and Evolution (q-bio.PE)
subject: Applications (stat.AP)
subject: FOS: Computer and information sciences
subject: FOS: Biological sciences

description: Continuous-time linear birth-death-immigration (BDI) processes are frequently used in ecology and epidemiology to model stochastic dynamics of the population of interest. In clinical settings, multiple birth-death processes can describe disease trajectories of individual patients, allowing for estimation of the effects of individual covariates on the birth and death rates of the process. Such estimation is usually accomplished by analyzing patient data collected at unevenly spaced time points, referred to as panel data in the biostatistics literature. Fitting linear BDI processes to panel data is a nontrivial optimization problem because birth and death rates can be functions of many parameters related to the covariates of interest. We propose a novel expectation--maximization (EM) algorithm for fitting linear BDI models with covariates to panel data. We derive a closed-form expression for the joint generating function of some of the BDI process statistics and use this generating function to reduce the E-step of the EM algorithm, as well as calculation of the Fisher information, to one-dimensional integration. This analytical technique yields a computationally efficient and robust optimization algorithm that we implemented in an open-source R package. We apply our method to DNA fingerprinting of Mycobacterium tuberculosis, the causative agent of tuberculosis, to study intrapatient time evolution of IS6110 copy number, a genetic marker frequently used during estimation of epidemiological clusters of Mycobacterium tuberculosis infections. Our analysis reveals previously undocumented differences in IS6110 birth-death rates among three major lineages of Mycobacterium tuberculosis, which has important implications for epidemiologists that use IS6110 for DNA fingerprinting of Mycobacterium tuberculosis.
description: Published in at http://dx.doi.org/10.1214/13-AOAS673 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org)
Few electron double quantum dot in an isotopically purified 28Si quantum well
Creators: name: Wild, A.
name: Kierig, Johannes
name: Sailer, J.
name: Ager, J. W.
name: Haller, E. E.
name: Abstreiter, Gerhard
name: Ludwig, S.
name: Bougeard, Dominique
Publisher: name: Universität Regensburg
Year: 2012
Subjects: subject: electron mobility, elemental semiconductors, Ge-Si alloys, hyperfine interactions, semiconductor heterojunctions, semiconductor quantum dots, semiconductor quantum wells, silicon
subject: 530 Physik
subject: 73.40.Lq
subject: 73.61.Cw
subject: 71.70.Jp

description: We present a few electron double quantum dot device defined in an isotopically purified 28Si quantum well (QW). An electron mobility of 5.5·104cm2(Vs)-1 is observed in the QW, which is the highest mobility ever reported for a two-dimensional electron system in 28Si. The residual concentration of 29Si nuclei in the 28Si QW is lower than 103ppm, at the verge where the hyperfine interaction is theoretically no longer expected to dominantly limit the T2 spin dephasing time. We also demonstrate a complete suppression of hysteretic gate behavior and charge noise using a negatively biased global top gate. © 2012 American Institute of Physics
microRNAs associated with the different human Argonaute proteins
Creators: name: Dueck, Anne
name: Ziegler, Christian
name: Eichner, Alexander
name: Berezikov, Eugene
name: Meister, Gunter
Publisher: name: Universität Regensburg
Year: 2012
Subjects: subject: 570 Biowissenschaften, Biologie

description: MicroRNAs (miRNAs) are small noncoding RNAs that function in literally all cellular processes. miRNAs interact with Argonaute (Ago) proteins and guide them to specific target sites located in the 3′-untranslated region (3′-UTR) of target mRNAs leading to translational repression and deadenylation-induced mRNA degradation. Most miRNAs are processed from hairpin-structured precursors by the consecutive action of the RNase III enzymes Drosha and Dicer. However, processing of miR-451 is Dicer independent and cleavage is mediated by the endonuclease Ago2. Here we have characterized miR-451 sequence and structure requirements for processing as well as sorting of miRNAs into different Ago proteins. Pre-miR-451 appears to be optimized for Ago2 cleavage and changes result in reduced processing. In addition, we show that the mature miR-451 only associates with Ago2 suggesting that mature miRNAs are not exchanged between different members of the Ago protein family. Based on cloning and deep sequencing of endogenous miRNAs associated with Ago1–3, we do not find evidence for miRNA sorting in human cells. However, Ago identity appears to influence the length of some miRNAs, while others remain unaffected.
Resonant spin amplification of hole spin dynamics in two‐dimensional hole systems: experiment and simulation
Creators: name: Korn, Tobias
name: Kugler, Michael
name: Hirmer, Michael
name: Schuh, Dieter
name: Wegscheider, Werner
name: Schüller, Christian
Publisher: name: Universität Regensburg
Year: 2010
Subjects: subject: quantum dots, temperature measurement, polarization
subject: 530 Physik
subject: 73.63.Kv
subject: 07.20.Dt
subject: 76.70.Fz

description: Spins in semiconductor structures may allow for the realization of scalable quantum bit arrays, an essential component for quantum computation schemes. Specifically, hole spins may be more suited for this purpose than electron spins, due to their strongly reduced interaction with lattice nuclei, which limits spin coherence for electrons in quantum dots. Here, we present resonant spin amplification (RSA) measurements, performed on a p‐modulation doped GaAs‐based quantum well at temperatures below 500 mK. The RSA traces have a peculiar, butterfly‐like shape, which stems from the initialization of a resident hole spin polarization by optical orientation. The combined dynamics of the optically oriented electron and hole spins are well‐described by a rate equation model, and by comparison of experiment and model, hole spin dephasing times of more than 70 ns are extracted from the measured data.
Relativistic mass and modern physics
Creators: name: Silagadze, Z. K.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Classical Physics (physics.class-ph)
subject: High Energy Physics - Theory (hep-th)
subject: Popular Physics (physics.pop-ph)
subject: FOS: Physical sciences

description: At first sight, arguments for and against the notion of relativistic mass look like a notorious intra-Lilliputian quarrel between Big-Endians (those who broke their eggs at the larger end) and Little-Endians. However, upon closer inspection we discover that the relativistic mass notion is alien to the spirit of modern physics to a much greater extent than it seems. To demonstrate an abyss between the modern approach and archaic notions, in this paper we explore how the concept of mass is introduced in modern physics. This modern approach reveals a deep cohomological origin of mass.
description: 13 pages, no figures. Title changed in the published version (without an entertaining part)
Anomalous antiferromagnetic coupling in Fe/Si/Fe structures with Co “dusting”
Creators: name: Gareev, R. R.
name: Buchmeier, M.
name: Kiesling, M.
name: Woltersdorf, Georg
name: Back, C. H.
Publisher: name: Universität Regensburg
Year: 2011
Subjects: subject: antiferromagnetic materials, chemical interdiffusion, cobalt, Curie temperature, elemental semiconductors, iron, magnetic multilayers, magnetisation, metal-semiconductor-metal structures, silicon
subject: 530 Physik
subject: 75.70.Cn
subject: 68.35.Fx
subject: 75.30.Kz
subject: 75.60.Ej

description: We report on anomalous antiferromagnetic coupling in Fe/Si/Fe epitaxial structures with interfacial cobalt “dusting”. Antiferromagnetic coupling exceeds 75 μJ/m2 for a 2.0 nm-thick Si spacer and is still detectable for a 2.3 nm-thick spacer at room temperature. From room temperature to T**∼150K the magnetization follows Bloch's law and the coupling shows metallic-type behaviour; for lower temperatures the coupling is of insulating type. Below T*∼50K an additional magnetic signal arises and the coupling becomes metallic-type again. We relate the observed features to the formation of inter-diffused magnetic FeCo-silicides with a Curie temperature close to 50 K.
The fundamental group of reductive Borel-Serre and Satake compactifications
Creators: name: Ji, Lizhen
name: Murty, V. Kumar
name: Saper, Leslie
name: Scherk, John
Publisher: name: arXiv
Year: 2011
Subjects: subject: Geometric Topology (math.GT)
subject: Group Theory (math.GR)
subject: Number Theory (math.NT)
subject: FOS: Mathematics
subject: 20F34, 22E40, 22F30 (Primary), 14M27, 20G30 (Secondary)

description: Let $G$ be an almost simple, simply connected algebraic group defined over a number field $k$, and let $S$ be a finite set of places of $k$ including all infinite places. Let $X$ be the product over $v\in S$ of the symmetric spaces associated to $G(k_v)$, when $v$ is an infinite place, and the Bruhat-Tits buildings associated to $G(k_v)$, when $v$ is a finite place. The main result of this paper is an explicit computation of the fundamental group of the reductive Borel-Serre compactification of $Γ\backslash X$, where $Γ$ is an $S$-arithmetic subgroup of $G$. In the case that $Γ$ is neat, we show that this fundamental group is isomorphic to $Γ/EΓ$, where $EΓ$ is the subgroup generated by the elements of $Γ$ belonging to unipotent radicals of $k$-parabolic subgroups. Analogous computations of the fundamental group of the Satake compactifications are made. It is noteworthy that calculations of the congruence subgroup kernel $C(S,G)$ yield similar results.
description: 21 pages, 1 figure, uses Xy-pic 3.8.6; in version 2, title changed to more accurately reflect main result, expository material on congruence subgroup problem removed, many small corrections and improvements in exposition
Low-temperature photocarrier dynamics in monolayer MoS2
Creators: name: Korn, Tobias
name: Heydrich, Stefanie
name: Hirmer, Michael
name: Schmutzler, Johannes
name: Schüller, Christian
Publisher: name: Universität Regensburg
Year: 2011
Subjects: subject: band structure, molybdenum compounds, monolayers, photoluminescence, Raman spectra, semiconductor materials
subject: 530 Physik
subject: 72.20.Jv
subject: 73.61.Le
subject: 78.30.Hv
subject: 78.55.Hx
subject: 78.67.-n
subject: 68.47.Pe

description: The band structure of MoS2 strongly depends on the number of layers, and a transition from indirect to direct-gap semiconductor has been observed recently for a single layer of MoS2. Single-layer MoS2 therefore becomes an efficient emitter of photoluminescence even at room temperature. Here, we report on scanning Raman and on temperature-dependent, as well as time-resolved photoluminescence measurements on single-layer MoS2 flakes prepared by exfoliation. We observe the emergence of two distinct photoluminescence peaks at low temperatures. The photocarrier recombination at low temperatures occurs on the few-picosecond timescale, but with increasing temperatures, a biexponential photoluminescence decay with a longer-lived component is observed.
Effects of screened Coulomb impurities on autoionizing two-electron resonances in spherical quantum dots
Creators: name: Genkin, Michael
name: Lindroth, Eva
Publisher: name: arXiv
Year: 2010
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: In a recent paper (Phys. Rev. B {\bf 78}, 075316 (2008)), Sajeev and Moiseyev demonstrated that the bound-to-resonant transitions and lifetimes of autoionizing states in spherical quantum dots can be controlled by varying the confinment strength. In the present paper, we report that such control can in some cases be compromised by the presence of Coulomb impurities. It is demonstrated that a screened Coulomb impurity placed in the vicinity of the dot center can lead to bound-to-resonant transitions and to avoided crossings-like behavior when the screening of the impurity charge is varied. It is argued that these properties also can have impact on electron transport through quantum dot arrays.
Optical conductivity of Ba0.6 K0.4 Fe2 As2 : The effect of in-plane and out-of-plane doping in the superconducting gap
Creators: name: Dai, Y. M.
name: Xu, B.
name: Shen, B.
name: Wen, H. H.
name: Qiu, X. G.
name: Lobo, R. P. S. M.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: We measured the in-plane optical conductivity of a nearly optimally doped (Ba,K)Fe2As2 single crystal with Tc = 39.1 K. Upon entering the superconducting state the optical conductivity below ~20 meV vanishes, strongly suggesting a fully gapped system. A BCS-like fit requires two different isotropic gaps to describe the optical response of this material. The temperature dependence of the gaps and the penetration depth suggest a strong interband coupling, but no impurity scattering induced pair breaking is present. This contrasts to the large residual conductivity observed in optimally doped Ba(Fe,Co)2As2 and strongly supports an s(+/-) gap symmetry for these compounds.
description: 5 pages, 4 figures -- Version and title updated to match published version
Density fields and halo mass functions in the Geometrical Adhesion toy Model
Creators: name: Valageas, Patrick
name: Bernardeau, Francis
Publisher: name: arXiv
Year: 2010
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: In dimension 2 and above, the Burgers dynamics, the so-called "adhesion model" in cosmology, can actually give rise to several dynamics in the inviscid limit. We investigate here the statistical properties of the density field when it is defined by a "geometrical model" associated with this Burgers velocity field and where the matter distribution is fully determined, at each time step, by geometrical constructions. Our investigations are based on a set of numerical experiments that make use of an improved algorithm, for which the geometrical constructions are efficient and robust. In this work we focus on Gaussian initial conditions with power-law power spectra of slope $n$ in the range $-3
description: 29 pages
Antiferromagnetic coupling across silicon regulated by tunneling currents
Creators: name: Gareev, R. R.
name: Schmid, M.
name: Vancea, Johann
name: Back, C. H.
name: Schreiber, Rainer
name: Bürgler, D.
name: Schneider, C. M.
name: Stromberg, F.
name: Wende, Heiko
Publisher: name: Universität Regensburg
Year: 2012
Subjects: subject: antiferromagnetic materials, ballistic transport, elemental semiconductors, hot carriers, iron, magnetisation, magnetoresistance, semiconductor-metal boundaries, silicon, spin polarised transport, tunnelling
subject: 530 Physik
subject: 73.40.Ns
subject: 75.50.Ee
subject: 75.60.Ej
subject: 72.20.Ht
subject: 72.20.My
subject: 72.25.-b

description: We report on the enhancement of antiferromagnetic coupling in epitaxial Fe/Si/Fe structures by voltage-driven spin-polarized tunneling currents. Using the ballistic electron magnetic microscopy, we established that the hot-electron collector current reflects magnetization alignment and the magnetocurrent exceeds 200% at room temperature. The saturation magnetic field for the collector current corresponding to the parallel alignment of magnetizations rises up with the tunneling current, thus demonstrating stabilization of the antiparallel alignment and increasing antiferromagnetic coupling. We connect the enhancement of antiferromagnetic coupling with local dynamic spin torques mediated by spin-polarized tunneling electrons.
Blood-based biomarker alterations in athletes following sub-concussive and concussive impacts
Creators: name: Wallace, Colin Anthony
Publisher: name: University of British Columbia
Year: 2017

description: Sport-related concussion affects an estimated 1.6 – 3.8 million people in the United States annually, and it has been suggested many more go unreported due to lack of knowledge regarding symptoms. Current diagnostic measures are based on subjective criteria, which rely heavily on self-reporting by the individual who has suffered the injury. Further, it is possible for symptoms of a concussion to manifest up to 72-hours post-injury, making it even more difficult to form a mechanistic link between trauma and symptoms. Recently, there has been an increased concern for the deleterious physiological effects of repetitive, sub-concussive impacts. An objective, quantifiable measure of the pathophysiological effects of both sub-concussive and concussive impacts is essential for concussion diagnosis, and could aid in tracking the pathophysiological processes underlying acute and repetitive mild traumatic head trauma. Three prospective cohort studies form the backbone of this dissertation. Study 1 examined plasma concentrations of total tau (T-tau), along with serum concentrations of neurofilament light (NF-L), A disintegrin and metalloproteinase domain-containing 10-(ADAM10) and caspase 3-cleaved fragments of tau (Tau-A and Tau-C, respectively) before and after a season of athletic competition in the following sports: American football, ice hockey, rugby, soccer, and cross country running. Study 2 examined NF-L before and after an acute bout of soccer heading. To complete the dissertation, Study 3 involved the quantification of these biomarkers at preseason and at 6- and 14-days following a concussion in American football, ice hockey, and soccer players. Serum NF-L appeared to be more sensitive to the effects of repetitive, sub-concussive impacts (i.e. studies 1 and 2) than a single, traumatic event resulting in a concussion (i.e. study 3), where it did not change. T-tau, Tau-A, and Tau-C were unaffected by both repetitive subconcussive impacts and impacts resulting in a concussion. Thus, it appears that serum NF-L may be a sensitive biomarker of axonal damage in repetitive sub-concussive and concussive contexts.
Transverse momentum dependent quark densities from Lattice QCD
Creators: name: Musch, B. U.
name: Hägler, Philipp
name: Negele, J. W.
name: Schäfer, Andreas
Publisher: name: Universität Regensburg
Year: 2010
Subjects: subject: renormalization, quark models, chiral symmetries, polarization
subject: 530 Physik
subject: 11.10.Gh
subject: 12.39.St
subject: 11.30.Rd
subject: 13.88.+e

description: We study transverse momentum dependent parton distribution functions (TMDs) with non‐local operators in lattice QCD, using MILC∕LHPC lattices. We discuss the basic concepts of the method, including renormalization of the gauge link. Results obtained with a simplified operator geometry show visible dipole deformations of spin‐dependent quark momentum densities.
A new ephemeris and an orbital solution of ε Aurigae
Creators: name: Chadima, Pavel
name: Harmanec, Petr
name: Yang, Stephenson
name: Bennett, Phillip D.
name: Božić, Hrvoje
name: Ruždjak, Domagoj
name: Sudar, Davor
name: Škoda, Petr
name: Šlechta, Miroslav
name: Wolf, Marek
name: Lehký, Martin
name: Dubovský, Pavol
Publisher: name: arXiv
Year: 2010
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We collected rich series of RV measurements covering last 110 years and photometric observations from the past 6 primary eclipses, complemented them by our new observations and derived a new precise ephemeris and an orbital solution of epsilon Aur.
description: accepted and published in IBVS (paper No. 5937)
Percolation-to-hopping crossover in conductor-insulator composites
Creators: name: Ambrosetti, G.
name: Balberg, I.
name: Grimaldi, C.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Here, we show that the conductivity of conductor-insulator composites in which electrons can tunnel from each conducting particle to all others may display both percolation and tunneling (i.e. hopping) regimes depending on few characteristics of the composite. Specifically, we find that the relevant parameters that give rise to one regime or the other are $D/ξ$ (where $D$ is the size of the conducting particles and $ξ$ is the tunneling length) and the specific composite microstructure. For large values of $D/ξ$, percolation arises when the composite microstructure can be modeled as a regular lattice that is fractionally occupied by conducting particle, while the tunneling regime is always obtained for equilibrium distributions of conducting particles in a continuum insulating matrix. As $D/ξ$ decreases the percolating behavior of the conductivity of lattice-like composites gradually crosses over to the tunneling-like regime characterizing particle dispersions in the continuum. For $D/ξ$ values lower than $D/ξ\simeq 5$ the conductivity has tunneling-like behavior independent of the specific microstructure of the composite.
description: 8 pages, 5 figures
Low melting mixtures in organic synthesis – an alternative to ionic liquids?
Creators: name: Ruß, Carolin
name: König, Burkhard
Publisher: name: Universität Regensburg
Year: 2012
Subjects: subject: sugar melts, ionic liquids, deep eutectic solvents
subject: 540 Chemie

description: There is a pressing need to replace hazardous and harmful solvents with “green” or “sustainable” media. Natural compounds have recently been used to produce deep eutectic solvents, sugar melts, or ionic liquids. This review presents physicochemical data of these reaction media and highlights recent advances in their use in organic synthesis and biotransformations.