cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Imaging silicon by atomic force microscopy with crystallographically oriented tips
Creators: name: Giessibl, Franz J.
name: Hembacher, Stefan
name: Bielefeldt, Hartmut
name: Mannhart, Jochen
Publisher: name: Universität Regensburg
Year: 2001
Subjects: subject: 530 Physik
subject: 07.79.Lh
subject: 34.20.Cf
subject: 68.37.E

description: The images obtained by atomic force microscopy (AFM) originate from a convolution of atomic tip and sample states. Since the vertical resolution of AFM is approaching the picometer level, the atomic and subatomic structure of the tip is becoming increasingly important. Here, we demonstrate the preparation of crystallographically oriented AFM tips by breaking a silicon wafer along its preferential cleavage planes. Assuming bulk termination, the front atom of this tip should expose a single dangling bond. Images derived with this tip are consistent with this speculated tip geometry and show unprecedented vertical distinction of the six different surface atom sites of the Si(111)-(727) structure.
First-post-Newtonian quadrupole tidal interactions in binary systems
Creators: name: Vines, Justin
name: Flanagan, Éanna É.
Publisher: name: arXiv
Year: 2010
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We consider tidal coupling in a binary stellar system to first-post-Newtonian order. We derive the orbital equations of motion for bodies with spins and mass quadrupole moments and show that they conserve the total linear momentum of the binary. We note that spin-orbit coupling must be included in a 1PN treatment of tidal interactions in order to maintain consistency (except in the special case of adiabatically induced quadrupoles); inclusion of 1PN quadrupolar tidal effects while omitting spin effects would lead to a failure of momentum conservation for generic evolution of the quadrupoles. We use momentum conservation to specialize our analysis to the system's center-of-mass-energy frame; we find the binary's relative equation of motion in this frame and also present a generalized Lagrangian from which it can be derived. We then specialize to the case in which the quadrupole moment is adiabatically induced by the tidal field (in which case it is consistent to ignore spin effects). We show how the adiabatic dynamics for the quadrupole can be incorporated into our action principle and present the simplified orbital equations of motion and conserved energy for the adiabatic case. These results are relevant to gravitational wave signals from inspiralling binary neutron stars.
description: 34 pages; updated to match published version
The scalar does not decay at finite temperatures
Creators: name: Banerjee, Debasish
name: Gavai, Rajiv
name: Gupta, Sourendu
Publisher: name: arXiv
Year: 2010
Subjects: subject: High Energy Physics - Lattice (hep-lat)
subject: FOS: Physical sciences

description: We investigate medium effects on mesonic screening lengths for QCD with 2-flavours of dynamical staggered quarks on lattices with cutoff a=1/6T. Denoting the cross-over temperature by $T_c$, we vary the temperature T from 0.89$T_c$ to 1.92$T_c$, spanning both the hadronic and quark gluon plasma phases. While chiral symmetry restoration in the vector channel appears to take place near $T_c$, it is seen in the scalar channel only above 1.33 $T_c$. Varying spatial lattice sizes, we find very little volume dependence in our results at 0.94 $T_c$. We discuss the stability of the scalar meson at these temperatures.
description: Talk presented at The XXVIII International Symposium on Lattice Field Theory, Lattice2010, June 14-19, 2010, Villasimius, Italy
Planar Yang-Mills 101.pdf
Creators: name: R. Wright, Nicholas
Publisher: name: figshare
Year: 2022
Subjects: subject: 20299 Atomic, Molecular, Nuclear, Particle and Plasma Physics not elsewhere classified
subject: FOS: Physical sciences
subject: 20399 Classical Physics not elsewhere classified
subject: 20499 Condensed Matter Physics not elsewhere classified
subject: 20601 Degenerate Quantum Gases and Atom Optics
subject: 20602 Field Theory and String Theory
subject: General Relativity
subject: M-Theory
subject: 20202 Nuclear Physics
subject: 20203 Particle Physics
subject: 20204 Plasma Physics; Fusion Plasmas; Electrical Discharges
subject: 20603 Quantum Information, Computation and Communication
subject: Quantum Mechanics
subject: 20699 Quantum Physics not elsewhere classified
subject: Special Relativity

description: The point is to define the limiting continuum field theory. In principle, this might even be done without taking limits. The Hamiltonian, the operator on the quantum Hilbert space which generates time translations, has a square root called the supercharge. Here we use the Moon model and Parfait logic. Furthermore, although one has changed the problem, one still has a fairly close relation to the original problem using the ideology of the renormalization group. We can start with a supersymmetric theory, and add supersymmetry breaking terms to the action which only become important at long distances as many lattice spacings, to obtain a theory with the better renormalization properties of the supersymmetric theory at short distances, but which reduces to conventional Yang-Mills theory at longer distances. Thus, a solution to the problem in a sufficiently general class of supersymmetric theories, would in fact imply the solution of the original problem. We propose a Cacace tetraoxygen universe relative to a Poincaré Dodecahedral Space. This is called an oxozone.
Atomic resolution on Si(111)-(7×7) by noncontact atomic force microscopy with a force sensor based on a quartz tuning fork
Creators: name: Giessibl, Franz J.
Publisher: name: Universität Regensburg
Year: 2000
Subjects: subject: 530 Physik

description: Atomic resolution by noncontact atomic force microscopy with a self-sensing piezoelectric force sensor is presented. The sensor has a stiffness of 1800 N/m and is operated with sub-nanometer amplitudes, allowing atomic resolution with relatively bluntly etched tungsten tips. Sensitivity and noise are discussed.
The writing center as a global pedagogy : a case study of a Japanese university seeking internationalization
Creators: name: Okuda (Otani), Tomoyo
Publisher: name: University of British Columbia
Year: 2017

description: The writing center is a common writing support service in North America with unique historical and theoretical underpinnings (Boquet, 1999; Bruffee, 1984; North, 1984). In the last couple of decades, it has truly become a global pedagogy, being implemented in around 65 countries worldwide (e.g., Archer, 2007; Bräuer, 2002; Tan, 2011). Although writing centers have been well received by international scholars, more studies are needed to discuss the economic and political imperatives of establishing writing centers in respective contexts and possible impacts on different student populations as a result. To address this issue, this multilayered case study explores how the educational philosophy, pedagogical rationale and concepts of the global writing pedagogy are interpreted by administrators and enacted in pedagogical practice at Maple Leaves University (MLU), an internationalizing university in Japan. To examine the language planning stage, data were collected from interviews with five administrators and relevant university documents. For pedagogical practices, primary data included audio-recordings and student interviews from four tutor-tutee dyads concerning three types of writing tutorials: (a) Japanese students seeking consultation on Japanese writing, (b) Japanese students seeking consultation on English writing, and (c) international students seeking consultation on Japanese writing. By looking at process of implementation from a language policy and practice perspective (Hornberger, 2005; Ricento & Hornberger, 1996), this study found that the MLU Writing Center was caught between ideal literacy/educational practices of a “world-class university” (Deem, Mok, & Lucas, 2008) and the local literacy realities at MLU. In the language planning, the internationalizing goals of a world-class university (e.g., English language policies, increasing international student enrollment, and student-centered education reforms) were the primary motives behind the establishment of MLU’s Writing Center. In tutorial practices, particular aspects of the Writing Center pedagogy were challenged by tutees’ disciplinary practices, beliefs towards non-native English tutors, and Japanese language learning needs. This study adds a policy perspective to the scholarship of writing centers, encouraging further research into the macro-context of writing centers and suggesting tutors be considered as key literacy educators who could better inform policy-making from the bottom-up.
System/environment duality of nonequilibrium observables
Creators: name: Polettini, Matteo
Publisher: name: arXiv
Year: 2011
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: On networks representing probability currents between states of a system, we generalize Schnakenberg's theory of nonequilibrium observables to nonsteady states, with the introduction of a new set of macroscopic observables that, for planar graphs, are related by a duality. We apply this duality to the linear regime, obtaining a dual proposition for the minimum entropy production principle, and to discrete electromagnetism, finding that it exchanges fields with sources. We interpret duality as reversing the role of system and environment, and discuss generalization to nonplanar graphs. The results are based on two theorems regarding the representation of bilinear and quadratic forms over the edge vector space of an oriented graph in terms of observables associated to cycles and cocycles.
description: 13 pages, 2 figures
Determinants of early pregnancy in Colombia: understanding the causes of the causes
Creators: name: Rocio  Murad
name: Rivillas, Juan Carlos
name: Gómez, Germán
name: Sicachá, Jorge
name: Vargas, Victoria
Publisher: name: F1000 Research Limited
Year: 2019

description: Early pregnancy has been considered a public health issue, with important social, economic and development effects. Therefore, policy implementation required multidimensional factors to act upon the social determinants of early pregnancies.

•According to the timeliness in the delivery and access to information on sexuality, on average, women aged 13 to 49 were 16 years old when they first accessed sexuality information. Women with lower school achievement received information on sexuality for the first time at age 22, while women with higher education received it for the first time at age 15.
•There is an even greater gap between women who have had more than 3 children, who received information about sexuality for the first time at age 21, and women who have not had children, who received it at age 13.
•The purpose of this analysis was disentangling the contribution of social determinants with those with major contributions in the occurrence of early pregnancy and parenthood in Colombia, based of the handbook for monitoring health inequalities.
Data sources:
Analysis based on the Colombian Demographic Health Survey 2015 - DHS, 2015. Three types of data were required for measuring inequalities: i) Data on the number of men and women under 18 years old, ii) data on socio-economic conditions and iii) data on stereotypes and ideas about gender relations.
•Statistical methods: regression analysis model was performed to explore contributions of social determinants explaining early pregnancies, as well as early motherhood and fatherhood.

Findings
•Poverty, area of residence and migration are the main structural determinants of early pregnancies in Colombia. The age and to attend school and gender stereotypes explain early pregnancies at the intrapersonal level. In other words, permanence in the school and the postponement of sex are the main determinants to prevent early pregnancies.
•On the other hand, gender stereotypes and cultural patterns related with gender-based violence, explain an important segment of the risk of early parenthood and pregnancy.
Device for in situ cleaving of hard crystals
Creators: name: Schmid, Martin
name: Renner, Andreas
name: Giessibl, Franz J.
Publisher: name: Universität Regensburg
Year: 2006
Subjects: subject: 530 Physik

description: Cleaving crystals in a vacuum chamber is a simple method for obtaining atomically flat and clean surfaces for materials with a preferential cleaving plane. Most in situ cleavers use parallel cutting edges that are applied from two sides on the sample. We found in ambient experiments that diagonal cutting pliers, where the cleavage force is introduced in a single point instead of a line, work very well also for hard materials. Here, we incorporate the diagonal cutting plier principle in a design compatible with ultrahigh-vacuum requirements. We show optical microscopy (millimeter scale) and atomic force microscopy (atomic scale) images of NiO(001) surfaces cleaved with this device.
On the Birch and Swinnerton-Dyer conjecture and ERG Theory.pdf
Creators: name: R. Wright, Nicholas
name: Steinert Wright, Nicholas R.
Publisher: name: figshare
Year: 2022
Subjects: subject: 10301 Numerical Analysis
subject: FOS: Mathematics

description: We prove the integrality and modularity of the Birch and Swinnerton-Dyer conjecture with ERG Theory. Inspection of the conjecture shows that it is a phenomenological model. Thus, a solution could be found through regression analysis. Numerical verification is possible through nominative determinism/visibility theory. By adding adaptive learning (AL) to the model, the model admits an important time variation in beliefs, which would be ruled out under rational expectations. Entropy can be given from a detailed molecular analysis of the system. In summary, perception consists of the selection, organization, and interpretation of stimuli. These factors affect the conduct of work. We include two inequalities on the log-volume change associated to appropriately chosen deformations.
Ideal games and Ramsey sets
Creators: name: Di Prisco, Carlos
name: Mijares, Jose G.
name: Uzcategui, Carlos
Publisher: name: arXiv
Year: 2010
Subjects: subject: Combinatorics (math.CO)
subject: Logic (math.LO)
subject: FOS: Mathematics
subject: 05D10, 03E02

description: It is shown that Matet's characterization of the Ramsey property relative to a selective co-ideal $\mathcal{H}$, in terms of games of Kastanas, still holds if we consider semiselectivity instead of selectivity. Moreover, we prove that a co-ideal $\mathcal{H}$ is semiselective if and only if Matet's game-theoretic characterization of the $\mathcal{H}$-Ramsey property holds. This lifts Kastanas's characterization of the classical Ramsey property to its optimal setting, from the point of view of the local Ramsey theory and gives a game-theoretic counterpart to a theorem of Farah \cite{far}, asserting that a co-ideal $\mathcal{H}$ is semiselective if and only if the family of $\mathcal{H}$-Ramsey subsets of $\N^{[\infty]}$ coincides with the family of those sets having the abstract $\mathcal{H}$-Baire property. Finally, we show that under suitable assumptions, for every semiselective co-ideal $\mathcal H$ all sets of real numbers are $\mathcal H$-Ramsey.
description: 11 pages
Revealing the hidden atom in graphite by low-temperature atomic force microscopy
Creators: name: Hembacher, Stefan
name: Giessibl, Franz J.
name: Mannhart, Jochen
name: Quate, Calvin F.
Publisher: name: Universität Regensburg
Year: 2003
Subjects: subject: 530 Physik

description: Carbon, the backbone material of life on Earth, comes in three modifications: diamond, graphite, and fullerenes. Diamond develops tetrahedral sp3 bonds, forming a cubic crystal structure, whereas graphite and fullerenes are characterized by planar sp2 bonds. Polycrystalline graphite is the basis for many products of everyday life: pencils, lubricants, batteries, arc lamps, and brushes for electric motors. In crystalline form, highly oriented pyrolytic graphite is used as a diffracting element in monochromators for x-ray and neutron scattering and as a calibration standard for scanning tunneling microscopy (STM). The graphite surface is easily prepared as a clean atomically flat surface by cleavage. This feature is attractive and is used in many laboratories as the surface of choice for “seeing atoms.” Despite the proverbial ease of imaging graphite by STM with atomic resolution, every second atom in the hexagonal surface unit cell remains hidden, and STM images show only a single atom in the unit cell. Here we present measurements with a low-temperature atomic force microscope with pico-Newton force sensitivity that reveal the hidden surface atom.
A new interpretation for the $D^*_{s2}(2573)$ and the prediction of novel exotic charmed mesons
Creators: name: Molina, R.
name: Branz, T.
name: Oset, E.
Publisher: name: arXiv
Year: 2010
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: In this manuscript we study the vector - vector interaction within the hidden gauge formalism in a coupled channel unitary approach. In the sector $C=1,S=1,J=2$ we get a pole in the T-matrix around $2572$ MeV that we identify with the $D^*_{s2}(2573)$, coupling strongly to the $D^*K^*$($D^*_sϕ$($ω$)) channels. In addition we obtain resonances in other exotic sectors which have not been studied before such as $C=1,S=-1$, $C=2,S=0$ and $C=2,S=1$. This 'flavor-exotic' states are interpreted as $D^*\bar{K^*}$, $D^*D^*$ and $D^*_sD^*$ molecular states but have not been observed yet. In total we obtain nine states with different spin, isospin, charm and strangeness of non $C=0,S=0$ and $C=1,S=0$ character, which have been reported before.
Spin-polarized electric currents in diluted magnetic semiconductor heterostructures induced by terahertz and microwave radiation
Creators: name: Olbrich, Peter
name: Zoth, Christina
name: Lutz, Peter
name: Drexler, Christoph
name: Belkov, Vassilij
name: Terent'ev, Ya. V.
name: Tarasenko, Sergey
name: Semenov, A. N.
name: Ivanov, S. V.
name: Yakovlev, D. R.
name: Wojtowicz, Tomasz
name: Wurstbauer, U.
name: Schuh, Dieter
name: Ganichev, Sergey
Publisher: name: Universität Regensburg
Year: 2012
Subjects: subject: 530 Physik
subject: 73.21.Fg, 72.25.Fe, 78.67.De, 73.63.Hs

description: We report on the study of spin-polarized electric currents in diluted magnetic semiconductor (DMS) quantum wells subjected to an in-plane external magnetic field and illuminated by microwave or terahertz radiation. The effect is studied in (Cd,Mn)Te/(Cd,Mg)Te quantum wells (QWs) and (In,Ga)As/InAlAs:Mn QWs belonging to the well known II-VI and III-V DMS material systems, as well as, in heterovalent AlSb/InAs/(Zn,Mn)Te QWs which represent a promising combination of II-VI and III-V semiconductors. Experimental data and developed theory demonstrate that the photocurrent originates from a spin-dependent scattering of free carriers by static defects or phonons in the Drude absorption of radiation and subsequent relaxation of carriers. We show that in DMS structures the efficiency of the current generation is drastically enhanced compared to non-magnetic semiconductors. The enhancement is caused by the exchange interaction of carrier spins with localized spins of magnetic ions resulting, on the one hand, in the giant Zeeman spin-splitting, and, on the other hand, in the spin-dependent carrier scattering by localized Mn2+ ions polarized by an external magnetic field.
Investigating atomic details of the CaF₂(111) surface with a qPlus sensor
Creators: name: Giessibl, Franz J.
name: Reichling, Michael
Publisher: name: Universität Regensburg
Year: 2005
Subjects: subject: 530 Physik

description: The (111) surface of CaF₂ has been intensively studied with large-amplitude frequency-modulation atomic force microscopy, and the atomic contrast formation is now well understood. It has been shown that the apparent contrast patterns obtained with a polar tip strongly depend on the tip terminating ion, and three sub-lattices of anions and cations can be imaged. Here, we study the details of atomic contrast formation on CaF₂(111) with small-amplitude force microscopy utilizing the qPlus sensor that has been shown to provide the utmost resolution at high scanning stability. Step edges resulting from cleaving crystals in situ in the ultra-high vacuum appear as very sharp structures, and on flat terraces the atomic corrugation is seen in high clarity even for large area scans. The atomic structure is also not lost when scanning across triple layer step edges. High-resolution scans of small surface areas yield contrast features of anion- and cation sub-lattices with unprecedented resolution. These contrast patterns are related to previously reported theoretical results.
Higher-order eigenmodes of qPlus sensors for high resolution dynamic atomic force microscopy
Creators: name: Tung, Raimond C.
name: Wutscher, Thorsten
name: Martinez-Martin, David
name: Reifenberger, Ronald G.
name: Giessibl, Franz J.
name: Raman, Arvind
Publisher: name: Universität Regensburg
Year: 2010
Subjects: subject: 530 Physik

description: The time response of tuning-fork based sensors can be improved by operating them at higher eigenmodes because a measurement takes at least one oscillation cycle in dynamic force microscopy and the oscillation period of the second eigenmode is only about one sixth of the fundamental mode. Here we study the higher-order eigenmodes of quartz qPlus sensors [ Bettac et al., Nanotechnology 20, 264009 (2009) ; Giessibl and Reichling, Nanotechnology 16, S118 (2005) ; Giessibl, Appl. Phys. Lett. 76, 1470 (2000) ; and Giessibl, Appl. Phys. Lett. 73, 3956 (1998) ], their equivalent stiffness, and piezoelectric sensitivity, while paying special attention to the influence of the mass and rotary inertia of the sensing tip which is attached to the end of the qPlus quartz cantilever. A combination of theoretical modeling and scanning laser Doppler vibrometry is used to study the eigenmodes of qPlus sensors with tungsten tips. We find that the geometry of tungsten tips can greatly influence the shape, equivalent stiffness, and piezoelectric sensitivity of the second eigenmode of the quartz cantilever. At a critical tip length it is possible to theoretically achieve infinite equivalent stiffness and infinite piezoelectric sensitivity when the tip becomes a perfect node of vibration and beyond this critical tip length the second eigenmode loses its vibration node and the trajectory of the tip reverses with respect to the beam curvature. The findings have major implications for optimizing tip geometry for high-resolution imaging with qPlus sensors using higher eigenmodes.
Stability considerations and implementation of cantilevers allowing dynamic force microscopy with optimal resolution: the qPlus sensor
Creators: name: Giessibl, Franz J.
name: Hembacher, Stefan
name: Herz, Markus
name: Schiller, C. H.
name: Mannhart, Jochen
Publisher: name: Universität Regensburg
Year: 2004
Subjects: subject: 530 Physik

description: In frequency modulation atomic force microscopy, the stiffness, quality factor and oscillation amplitude of the cantilever are important parameters. While the first atomic resolution results were obtained with amplitudes of a few hundred ångstrom, it has subsequently been shown that smaller amplitudes should result in a better signal-to-noise ratio and an increased sensitivity to the short-range components of the tip–sample interaction. Stable oscillation at small amplitudes is possible if the product of stiffness and amplitude and the energy stored in the oscillating cantilever are large enough. For small amplitudes, stability can be achieved by using stiff cantilevers. Here, we discuss the physical requirements for small amplitude operation and present design criteria and technical details of the qPlus sensor, a self-sensing cantilever with large stiffness that allows small amplitude operation.
Morse Homology for the Yang-Mills Gradient Flow
Creators: name: Swoboda, Jan
Publisher: name: arXiv
Year: 2011
Subjects: subject: Differential Geometry (math.DG)
subject: FOS: Mathematics
subject: 58E15

description: We use the Yang-Mills gradient flow on the space of connections over a closed Riemann surface to construct a Morse-Bott chain complex. The chain groups are generated by Yang-Mills connections. The boundary operator is defined by counting the elements of appropriately defined moduli spaces of Yang-Mills gradient flow lines that converge asymptotically to Yang-Mills connections.
description: 83 pages
AFM's path to atomic resolution
Creators: name: Giessibl, Franz J.
Publisher: name: Universität Regensburg
Year: 2005
Subjects: subject: 530 Physik

description: We review progress in improving the spatial resolution of atomic force microscopy (AFM) under vacuum. After an introduction to the basic imaging principle and a conceptual comparison to scanning tunneling microscopy (STM), we outline the main challenges of AFM as well as the solutions that have evolved in the first 20 years of its existence. Some crucial steps along AFM's path toward higher resolution are discussed, followed by an outlook on current and future applications.
Simultaneous current-, force-, and work-function measurement with atomic resolution
Creators: name: Herz, Markus
name: Schiller, Christian H.
name: Giessibl, Franz J.
name: Mannhart, Jochen
Publisher: name: Universität Regensburg
Year: 2005
Subjects: subject: 530 Physik

description: The local work function of a surface determines the spatial decay of the charge density at the Fermi level normal to the surface. Here, we present a method that enables simultaneous measurements of local work-function and tip-sample forces. A combined dynamic scanning tunneling microscope and atomic force microscope is used to measure the tunneling current between an oscillating tip and the sample in real time as a function of the cantilever’s deflection. Atomically resolved work-function measurements on a silicon (111)−(7×7) surface are presented and related to concurrently recorded tunneling current and force measurements.
The Force Needed to Move an Atom on a Surface
Creators: name: Ternes, Markus
name: Lutz, Christopher P.
name: Hirjibehedin, Cyrus F.
name: Giessibl, Franz J.
name: Heinrich, Andreas J.
Publisher: name: Universität Regensburg
Year: 2008
Subjects: subject: 530 Physik

description: Manipulation of individual atoms and molecules by scanning probe microscopy offers the ability of controlled assembly at the single-atom scale. However, the driving forces behind atomic manipulation have not yet been measured. We used an atomic force microscope to measure the vertical and lateral forces exerted on individual adsorbed atoms or molecules by the probe tip. We found that the force that it takes to move an atom depends strongly on the adsorbate and the surface. Our results indicate that for moving metal atoms on metal surfaces, the lateral force component plays the dominant role. Furthermore, measuring spatial maps of the forces during manipulation yielded the full potential energy landscape of the tip-sample interaction.
On the Birch and Swinnerton-Dyer conjecture and ERG Theory.pdf
Creators: name: R. Wright, Nicholas
Publisher: name: figshare
Year: 2022
Subjects: subject: 10301 Numerical Analysis
subject: FOS: Mathematics

description: We prove the integrality and modularity of the Birch and Swinnerton-Dyer conjecture with ERG Theory. Inspection of the conjecture shows that it is a phenomenological model. Thus, a solution could be found through regression analysis. Numerical verification is possible through nominative determinism/visibility theory. By adding adaptive learning (AL) to the model, the model admits an important time variation in beliefs, which would be ruled out under rational expectations. Entropy can be given from a detailed molecular analysis of the system. In summary, perception consists of the selection, organization, and interpretation of stimuli. These factors affect the conduct of work. We include two inequalities on the log-volume change associated to appropriately chosen deformations.
Self-oscillating mode for frequency modulation noncontact atomic force microscopy
Creators: name: Giessibl, Franz J.
name: Tortonese, Marco
Publisher: name: Universität Regensburg
Year: 1997
Subjects: subject: 530 Physik

description: Frequency modulation atomic force microscopy (FM-AFM) has made imaging of surfaces in ultrahigh vacuum with atomic resolution possible. Here, we demonstrate a new approach which simplifies the implementation of FM-AFM considerably and enhances force sensitivity by directly exciting the cantilever with the thermal effects involved in the deflection measurement process. This approach reduces the mechanically oscillating mass by 6 to 8 orders of magnitude as compared to conventional FM-AFM, because external actuators and oscillating cantilever mounts are not needed. Avoiding external actuators allows the use of cantilevers with very high oscillation frequencies, which results in improved force sensitivity. Further, the implementation and operation of this new technique is significantly simplified, because external actuator, bandpass filter, and phase shifter are eliminated.
Scale without Conformal Invariance: An Example
Creators: name: Fortin, Jean-François
name: Grinstein, Benjamín
name: Stergiou, Andreas
Publisher: name: arXiv
Year: 2011
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We give an explicit example of a model in D=4-epsilon space-time dimensions that is scale but not conformally invariant, is unitary, and has finite correlators. The invariance is associated with a limit cycle renormalization group (RG) trajectory. We also prove, to second order in the loop expansion, in D=4-epsilon, that scale implies conformal invariance for models of any number of real scalars. For models with one real scalar and any number of Weyl spinors we show that scale implies conformal invariance to all orders in perturbation theory.
description: 13 pages, 2 figures, Erratum added
Anion exchange resins for the removal of microcystins from surface water
Creators: name: Dixit, Fuhar
Publisher: name: University of British Columbia
Year: 2017

description: Harmful algal blooms have markedly increased in frequency over the past two decades, due to rising global temperatures and chemical runoff produced by modern farming practices. Cyanobacteria, also known as the blue green algae, are an essential part of the aquatic food chain. Cyanobacterial toxins, which are released from the algal biomass, can contaminate drinking, recreational and agricultural water reserves. Such environmental and health hazards pose a serious threat to communities and many aquatic ecosystems. In particular, small, shallow lakes that are sources of drinking water for rural communities have been particularly affected by elevated levels of algal toxins. Conventional water treatment systems are inefficient in removing these toxins, and may produce hazardous by-products. Additionally, the effectiveness of chemical oxidants, like chlorine and ozone, is hindered by the presence of natural organic matter (NOM) and inorganic ions in the contaminated water. Such challenges reveal the need for alternative treatment technologies capable of removing algal toxins. Anionic ion exchange (IX) resins offer a promising and cost-effective treatment alternative for natural waters affected by high algal content and high dissolved organic carbon (DOC) levels. This research investigates the efficiency of strongly basic ion exchange resins for the removal of microcystin-LR (MCLR), the most common toxin released from the algal biomass, inorganic ions, and NOM from natural water sources. We focused specifically on optimizing resin dosage, resin regeneration, and scaling up such procedures for particular source waters. Our results showed that the resin exhibited an excellent adsorption capacity of 3850 µg/L, removing more than 80% of the MCLR within 10 minutes at examined resin dosages (10 to 1000 mg/L; 1mL of resin = 221 mg). Additionally, we examined the influence of operating parameters such as pH and adsorption capacity of the resin, as well as the impact of NOM fractions on the uptake of MCLR. The charge density and molecular weight of the source water NOM were found to play a major competitive role in the uptake of Microcystin-LR. The results of this study bring the promising potential of IX resins for the removal of Microcystins and NOM from surface waters to light.
On the ABC Conjecture The Iron Law of Sines or Using Collatz Conjecture to solve the ABC Conjecture.pdf
Creators: name: R. Wright, Nicholas
name: Steinert Wright, Nicholas R.
Publisher: name: figshare
Year: 2022
Subjects: subject: 10101 Algebra and Number Theory
subject: FOS: Mathematics

description: This proof identifies the three solutions to the three ABC-conjecture formulations. Given that the ABC-conjecture’s relevance to a slew of unsolved problems, other equations will be proven by inspection. Aside from the ABC conjecture, this proof will solve for a hypothetical Moore graph of diameter 2, girth 5, degree 57 and order 3250 (degree-diameter problem); the Collatz conjecture; and the Beal conjecture. Discussion and conclusion will review a unifying solution by spectral graph theory.
Helicity sensitive terahertz radiation detection by field effect transistors
Creators: name: Drexler, Christoph
name: Dyakonova, Nina
name: Olbrich, Peter
name: Karch, Johannes
name: Schafberger, Michael
name: Karpierz, K.
name: Mityagin, Yu
name: Lifshits, M. B.
name: Teppe, F.
name: Klimenko, O.
name: Meziani, Y. M.
name: Knap, W.
name: Ganichev, Sergey
Publisher: name: Universität Regensburg
Year: 2012
Subjects: subject: aluminium compounds, gallium arsenide, high electron mobility transistors, III-V semiconductors, terahertz wave detectors
subject: 530 Physik
subject: 85.30.Tv
subject: 07.57.Pt

description: Terahertz light helicity sensitive photoresponse in GaAs/AlGaAs high electron mobility transistors. The helicity dependent detection mechanism is interpreted as an interference of plasma oscillations in the channel of the field-effect-transistors (generalized Dyakonov-Shur model). The observed helicity dependent photoresponse is by several orders of magnitude higher than any earlier reported one. Also, linear polarization sensitive photoresponse was registered by the same transistors. The results provide the basis for a new sensitive, all-electric, room-temperature, and fast (better than 1 ns) characterisation of all polarization parameters (Stokes parameters) of terahertz radiation. It paves the way towards terahertz ellipsometry and polarization sensitive imaging based on plasma effects in field-effect-transistors.
Friction traced to the single atom
Creators: name: Giessibl, Franz J.
name: Herz, Markus
name: Mannhart, Jochen
Publisher: name: Universität Regensburg
Year: 2002
Subjects: subject: 530 Physik

description: Friction is caused by dissipative lateral forces that act between macroscopic objects. An improved understanding of friction is therefore expected from measurements of dissipative lateral forces acting between individual atoms. Here we establish atomic resolution of both conservative and dissipative forces by lateral force microscopy, presenting the resolution of atomic defects. The interaction between a single-tip atom that is oscillated parallel to an Si(111)-(7 × 7) surface is measured. A dissipation energy of up to 4 eV per oscillation cycle is found. The dissipation is explained by a “plucking action of one atom on to the other” as described by G. A. Tomlinson in 1929 [Tomlinson, G. A. (1929) Phil. Mag. 7, 905–939].
Axial charges of octet and decuplet baryons
Creators: name: Choi, Ki-Seok
name: Plessas, W.
name: Wagenbrunn, R. F.
Publisher: name: arXiv
Year: 2010
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: We present a study of axial charges of baryon ground and resonant states with relativistic constituent quark models. In particular, the axial charges of octet and decuplet $N$, $Σ$, $Ξ$, $Δ$, $Σ^*$, and $Ξ^*$ baryons are considered. The theoretical predictions are compared to existing experimental data and results from other approaches, notably from lattice quantum chromodynamics and chiral perturbation theory. The relevance of axial charges with regard to $π$-dressing and spontaneous chiral-symmetry breaking is discussed.
On the ABC Conjecture The Iron Law of Sines or Using Collatz Conjecture to solve the ABC Conjecture.pdf
Creators: name: R. Wright, Nicholas
Publisher: name: figshare
Year: 2022
Subjects: subject: 10101 Algebra and Number Theory
subject: FOS: Mathematics

description: This proof identifies the three solutions to the three ABC-conjecture formulations. Given that the ABC-conjecture’s relevance to a slew of unsolved problems, other equations will be proven by inspection. Aside from the ABC conjecture, this proof will solve for a hypothetical Moore graph of diameter 2, girth 5, degree 57 and order 3250 (degree-diameter problem); the Collatz conjecture; and the Beal conjecture. Discussion and conclusion will review a unifying solution by spectral graph theory.
The Birch and Swinnerton-Dyer conjecture & the Conservation of Super-gravity: on Stargates and Warp Drives.pdf
Creators: name: R. Wright, Nicholas
name: Steinert Wright, Nicholas R.
Publisher: name: figshare
Year: 2022
Subjects: subject: 20102 Astronomical and Space Instrumentation
subject: FOS: Physical sciences
subject: 20199 Astronomical and Space Sciences not elsewhere classified
subject: Astrophysics
subject: 20104 Galactic Astronomy
subject: 20106 High Energy Astrophysics; Cosmic Rays
subject: 20105 General Relativity and Gravitational Waves
subject: Instrumentation, Techniques, and Astronomical Observations
subject: Solar System, Solar Physics, Planets and Exoplanets
subject: Space Science
subject: 20109 Space and Solar Physics
subject: Stars, Variable Stars
subject: Stellar Astronomy
subject: 20110 Stellar Astronomy and Planetary Systems

description: An addendum to two previously published papers: On the Birch and Swinnerton-Dyer conjecture and ERG Theory, and Planar Yang-Mills 101; respectively. I formulate a law for the conservation of supergravity, called the law of conservation of extreme grav in the Planar Yang-Mills 101 paper. I then construct a stargate or warp drive with the spatial localization problem and the circle of Apollonius. An allusion to bearing off checkers in the game of backgammon is made.
On Unit Distances in a Convex Polygon
Creators: name: Aggarwal, Amol
Publisher: name: arXiv
Year: 2010
Subjects: subject: Computational Geometry (cs.CG)
subject: FOS: Computer and information sciences

description: In 1959, Erdős and Moser asked for the maximum number of unit distances that may be formed among the vertices of a convex $n$-gon; until now, the best known upper bound has been $2πn \log_2 n + O(n)$, achieved by Füredi in 1990. In this paper, we examine two properties that any convex polygon must satisfy and use them to prove several new facts related to the question posed by Erdős and Moser. In particular, we improve on Füredi's result, and instead obtain a bound of $n \log_2 n + O(n)$; we exhibit a class of `cycles' formed by unit distances that are forbidden in convex polygons; and we provide a lower bound that shows the limitations of our methods. The second result addresses a question asked by Fishburn and Reeds regarding the possible configurations of vertices that form a convex polygon.
description: 7 pages, no figures
Advances in Atomic Force Microscopy
Creators: name: Giessibl, Franz J.
Publisher: name: Universität Regensburg
Year: 2003
Subjects: subject: 530 Physik

description: This article reviews the progress of atomic force microscopy in ultrahigh vacuum, starting with its invention and covering most of the recent developments. Today, dynamic force microscopy allows us to image surfaces of conductors and insulators in vacuum with atomic resolution. The most widely used technique for atomic-resolution force microscopy in vacuum is frequency-modulation atomic force microscopy (FM-AFM). This technique, as well as other dynamic methods, is explained in detail in this article. In the last few years many groups have expanded the empirical knowledge and deepened our theoretical understanding of frequency-modulation atomic force microscopy. Consequently spatial resolution and ease of use have been increased dramatically. Vacuum atomic force microscopy opens up new classes of experiments, ranging from imaging of insulators with true atomic resolution to the measurement of forces between individual atoms.
Symplectic groupoids and discrete constrained Lagrangian mechanics
Creators: name: Marrero, Juan Carlos
name: de Diego, David Martín
name: Stern, Ari
Publisher: name: arXiv
Year: 2011
Subjects: subject: Symplectic Geometry (math.SG)
subject: Dynamical Systems (math.DS)
subject: Optimization and Control (math.OC)
subject: FOS: Mathematics
subject: Primary 70G45, Secondary 53D17, 37M15

description: In this article, we generalize the theory of discrete Lagrangian mechanics and variational integrators in two principal directions. First, we show that Lagrangian submanifolds of symplectic groupoids give rise to discrete dynamical systems, and we study the properties of these systems, including their regularity and reversibility, from the perspective of symplectic and Poisson geometry. Next, we use this framework -- along with a generalized notion of generating function due to Sniatycki and Tulczyjew -- to develop a theory of discrete constrained Lagrangian mechanics. This allows for systems with arbitrary constraints, including those which are non-integrable (in an appropriate discrete, variational sense). In addition to characterizing the dynamics of these constrained systems, we also develop a theory of reduction and Noether symmetries, and study the relationship between the dynamics and variational principles. Finally, we apply this theory to discretize several concrete examples of constrained systems in mechanics and optimal control.
description: 36 pages; v2: minor revisions
Wie viel Kraft ist nötig, um ein Atom zu bewegen?
Creators: name: Ternes, Markus
name: Heinrich, Andreas J.
name: Giessibl, Franz J.
Publisher: name: Universität Regensburg
Year: 2008
Subjects: subject: 530 Physik

description: Bei mechanischen Konstruktionen benötigt man umfassendes Wissen über die Kräfte, die zwischen den Bauteilen wirken. Zum Beispiel ist es wichtig zu wissen, wie viel Kraft man aufwenden muss, um zwei Einzelteile gegeneinander zu verschieben. Dies trifft auch auf der atomaren Ebene zu. Einer Forschergruppe bei IBM in Kalifornien ist es jetzt zum ersten Mal gelungen, die Kräfte zu messen, die nötig sind, um Atome oder Moleküle auf einer Kristalloberfläche zu bewegen.
Towards more inclusive research information
Creators: name: University of Milan
Publisher: name: Zenodo
Year: 2024

description:  

Signing a declaration can make a difference only if there is a supportive context to implement the resulting actions. This includes a clear vision, appropriate policies, and necessary resources. At the University of Milan, this context includes: a 16-person open science support team, Italy's most extensive institutional and data repositories, a dedicated committee representing all departments and roles, ongoing updates on open science issues, a major diamond open access university press, and a comprehensive open science training system at all levels.

Here, we will introduce our new dashboard that maps collaboration at the level of each researcher, research group and department with institutions worldwide. Based on the University’s institutional repository, AIR (https://air.unimi.it), and OpenAlex (https://openalex.org), our dashboard can exhaustively map research output by using inclusive, open, reusable, and equitable tools instead of closed and expensive bibliometric tools that do not ensure sufficient coverage of important research fields and publication outlet. After providing a live pilot demonstration, we will share some lessons learned and discuss certain limitations, some already resolved, others still in process.

Our dashboard is part of the University’s broader effort to create an open infrastructure, aligning with COARA and UNESCO recommendations, that supports more context-specific and inclusive monitoring systems fully reflecting open science governance principles.
Final Report --- Always Already Computational: Collections as Data
Creators: name: Padilla, Thomas
name: Allen, Laurie
name: Frost, Hannah
name: Potvin, Sarah
name: Russey Roke, Elizabeth
name: Varner, Stewart
Publisher: name: Zenodo
Year: 2019
Subjects: archives
libraries
museums
collections
data

description: From 2016-2018 Always Already Computational: Collections as Data documented, iterated on, and shared current and potential approaches to developing cultural heritage collections that support computationally-driven research and teaching. With funding from the Institute of Museum and Library Services, Always Already Computational held two national forums, organized multiple workshops, shared project outcomes in disciplinary and professional conferences, and generated nearly a dozen deliverables meant to guide institutions as they consider development of collections as data. This report documents the activities and impacts of the Always Already Computational project, delineates findings, and identifies areas for further inquiry. This publication is part of the Collections as Data Framework hosted at https://osf.io/mx6uk/.
About The Second Neighborhood Problem in Tournaments Missing Disjoint Stars
Creators: name: Ghazal, Salman
Publisher: name: arXiv
Year: 2011
Subjects: subject: Combinatorics (math.CO)
subject: FOS: Mathematics
subject: 05C20

description: We prove Seymour's Second Neighborhood Conjecture when the missing graph is disjoint stars under some conditions. Weaker conditions are required when n=2 or 3. In some cases, we exhibit two vertices with the desired property.