Edge Enhancement Investigations by Means of Experiments and Simulations

Standard neutron imaging procedures are based on the “shadow” of the transmitted radiation, attenuated by the sample material. Under certain conditions significant deviations from pure transmission can be found in the form of enhancement or depression at the edges of the samples. These effects can limit the quantification process in the related regions. Otherwise, an enhancement and improvement of visibility can be achieved e.g. in defect analysis. In systematic studies we investigated the dependency of these effects on the specific material (mainly for common metals), such as the sample-to-detector distance, the beam collimation, the material thickness and the neutron energy. The beam lines ICON and BOA at PSI and ANTARES at TU München were used for these experiments due to their capability for neutron imaging with highest possible spatial resolution (6.5 to 13.5 micro-meter pixel size, respectively) and their cold beam spectrum. Next to the experimental data we used a McStas tool for the description of refraction and reflection features at edges for comparison. Even if minor contributions by coherent in-line propagation phase contrast are underlined, the major effect can be described by refraction of the neutrons at the sample-void interface. Ways to suppress and to magnify the edge effects can be derived from these findings.Fil: Lehmann, E.. Paul Scherrer Institut; SuizaFil: Schulz, M.. Technische Universitat Munchen; AlemaniaFil: Wang, Y.. China Insititute of Atomic Energy; ChinaFil: Tartaglione, Aureliano. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Seasonal variation of aliphatic amines in marine sub-micrometer particles at the Cape Verde islands

Monomethylamine (MA), dimethylamine (DMA) and diethylamine (DEA) were detected at non-negligible concentrations in sub-micrometer particles at the Cap Verde Atmospheric Observatory (CVAO) located on the island of São Vicente in Cape Verde during algal blooms in 2007. The concentrations of these amines in five stage impactor samples ranged from 0–30 pg m−3 for MA, 130–360 pg m−3 for DMA and 5–110 pg m−3 for DEA during the spring bloom in May 2007 and 2–520 pg m−3 for MA, 100–1400 pg m−3 for DMA and 90–760 pg m−3 for DEA during an unexpected winter algal bloom in December 2007. Anomalously high Saharan dust deposition and intensive ocean layer deepening were found at the Atmospheric Observatory and the associated Ocean Observatory during algal bloom periods. The highest amine concentrations in fine particles (impactor stage 2, 0.14–0.42 μm) indicate that amines are likely taken up from the gas phase into the acidic sub-micrometer particles. The contribution of amines to the organic carbon (OC) content ranged from 0.2–2.5% C in the winter months, indicating the importance of this class of compounds to the carbon cycle in the marine environment. Furthermore, aliphatic amines originating from marine biological sources likely contribute significantly to the nitrogen content in the marine atmosphere. The average contribution of the amines to the detected nitrogen species in sub-micrometer particles can be non-negligible, especially in the winter months (0.1% N–1.5% N in the sum of nitrate, ammonium and amines). This indicates that these smaller aliphatic amines can be important for the carbon and the nitrogen cycles in the remote marine environment

Person prominence and relation prominence : on the typology of syntactic relations with particular reference to Yucatec Maya

PM3969, ISO 639-3 : -, Maya language--Syntax1. Introduction 2. Theoretical background 2.1. The cognitive structure of a situation 2.1.1. Situation, situation core, and participants 2.1.2. Participant features 2.1.3. Participant roles 2.2. Syntactic functions 2.3. Correlation between syntactic functions and participant roles 3. Prominence in typology 3.1. Subject prominence vs. topic prominence 3.2. Reference domination vs. role domination 3.3. Person prominence vs. relation prominence 4. Languages investigated 4.1. Yucatec Maya 4.2. Samoan 4.3. Maori 4.4. Tamil 4.5. Lezgian 4.6. Korean 5. Prominence in syntactic constructions 5.1. Introduction 5.2. Higher predicates 5.2.1. Modal predicates 5.2.2. Phase predicates 5.2.3. Tense, aspect, and aktionsart auxiliaries 5.3. Possessive constructions 5.3.1. Part-whole relations 5.3.2. Ascription of possession 5.3.3. Predication of belonging 5.3.4. Ascription of property to body part 5.3.5. Affection of possessor 5.4. Mental, sensual, and emotional states and processes 5.4.1. Preliminaries 5.4.2. Sensual states and processes 5.4.3. Emotional states and processes 5.4.4. Mental states and processes 5.4.5. Conclusion 5.5. Benefactive 6. Relation prominence in YM: a historical-comparative perspective 6.1. Colonial Yucatec Maya 6.1.1. Preliminaries 6.1.2. Modal predicates 6.1.3. Phase predicates 6.1.4. Aspect auxiliaries 6.1.5. Conclusion 6.2. Cognate languages 6.2.1. Preliminaries 6.2.2. Higher predicates 6.2.3. Possessive constructions 6.2.4. Mental, sensual and emotional states and processes 6.2.5. Benefactive 6.2.6. Conclusion 7. Typology 7.1. Empirical generalizations 7.1.1. The domain of possession 136 7.1.2. Higher predicates 7.1.3. Participant roles 7.2. Grammatical correlations 7.3. Conclusion Indices Abbreviations Morpheme glosses & syntactic categories Languages Sources of data Bibliographical references LIST OF FIGURES LIST OF TABLE

Impact of the COVID-19 pandemic on adherence to infection prevention and control measures between 2019 and 2021 in Swiss sentinel private practices: repeated cross-sectional surveys.

The COVID-19 pandemic has shown the importance of infection prevention and control (IPC) measures in health care settings, including primary care. We aimed to describe how it influenced adherence to infection prevention and control measures in private practices in the Swiss sentinel network (Sentinella). An online cross-sectional survey was sent to the 181 Sentinella practices in 2021 that included questions on the practice's spatial organisation, staff habits and vaccination coverage, ventilation, mask wearing, hand hygiene, as well as triage and separation of patients with suspected infection. Results were compared with those of a 2019 survey conducted in the same setting. We received 127 valid questionnaires (70.2% response rate). At the time of the study, SARS-CoV-2 vaccination was underway among physicians (51.3%). Between 2019 and 2021, an absence of specific recommendations on mask wearing for staff (55.7%) changed into a recommendation for continuous wearing (93.7%); hand hygiene improved, especially upon arrival at the practice (63.9% vs 85.8%; p <0.001) and before examining patients (74.6% vs 88.2%; p <0.010); impossibility of distancing symptomatic patients dropped (27.9% vs 3.9%, p <0.001); and ventilation and cleaning improved (p <0.001). The COVID-19 pandemic led to important changes in adherence to the recommended IPC measures

Computing Stable Coalitions: Approximation Algorithms for Reward Sharing

Consider a setting where selfish agents are to be assigned to coalitions or projects from a fixed set P. Each project k is characterized by a valuation function; v_k(S) is the value generated by a set S of agents working on project k. We study the following classic problem in this setting: "how should the agents divide the value that they collectively create?". One traditional approach in cooperative game theory is to study core stability with the implicit assumption that there are infinite copies of one project, and agents can partition themselves into any number of coalitions. In contrast, we consider a model with a finite number of non-identical projects; this makes computing both high-welfare solutions and core payments highly non-trivial. The main contribution of this paper is a black-box mechanism that reduces the problem of computing a near-optimal core stable solution to the purely algorithmic problem of welfare maximization; we apply this to compute an approximately core stable solution that extracts one-fourth of the optimal social welfare for the class of subadditive valuations. We also show much stronger results for several popular sub-classes: anonymous, fractionally subadditive, and submodular valuations, as well as provide new approximation algorithms for welfare maximization with anonymous functions. Finally, we establish a connection between our setting and the well-studied simultaneous auctions with item bidding; we adapt our results to compute approximate pure Nash equilibria for these auctions.Comment: Under Revie

Effect of periodic parametric excitation on an ensemble of force-coupled self-oscillators

We report the synchronization behavior in a one-dimensional chain of identical limit cycle oscillators coupled to a mass-spring load via a force relation. We consider the effect of periodic parametric modulation on the final synchronization states of the system. Two types of external parametric excitations are investigated numerically: periodic modulation of the stiffness of the inertial oscillator and periodic excitation of the frequency of the self-oscillatory element. We show that the synchronization scenarios are ruled not only by the choice of parameters of the excitation force but depend on the initial collective state in the ensemble. We give detailed analysis of entrainment behavior for initially homogeneous and inhomogeneous states. Among other results, we describe a regime of partial synchronization. This regime is characterized by the frequency of collective oscillation being entrained to the stimulation frequency but different from the average individual oscillators frequency.Comment: Comments and suggestions are welcom

Multiple Components of the Luminous Compact X-ray Source at the Edge of Holmberg II observed by ASCA and ROSAT

We report the results of the analysis of ASCA/ROSAT observations of the compact luminous X-ray source found at the edge of the nearby star-forming dwarf galaxy Holmberg II (UGC 4305).Our ASCA spectrum revealed that the X-ray emission extends to the hard band and can be best described by a power-law with a photon spectral index of 1.9. The ASCA spectrum does not fit with a multi-color disk blackbody. The joint ASCA-ROSAT spectrum suggests two components to the spectrum: the hard power-law component and a warm thermal plasma kT~0.3[keV]. An additional absorption over that of our galaxy is required. The wobble correction of the ROSAT HRI image has clearly unveiled the existence of an extended component which amounts to 27+/-5% of the total X-ray emission. These observations indicate that there are more than one component in the X-ray emission. The properties of the point-like component is indicative of an accretion onto an intermediate mass blackhole, unless a beaming is taking place. We argue that the extended component does not come from electron scattering and/or reflection by scattered optically-thick clouds of the central radiation. Possible explanations of this X-ray source include multiple supernova remnants feeding an intermediate-mass blackhole. (abridged)Comment: 12 pages, 6 figures accepted to Astronomical Journa

Statistics of S-matrix poles for chaotic systems with broken time reversal invariance: a conjecture

In the framework of a random matrix description of chaotic quantum scattering the positions of $S-$matrix poles are given by complex eigenvalues $Z_i$ of an effective non-Hermitian random-matrix Hamiltonian. We put forward a conjecture on statistics of $Z_i$ for systems with broken time-reversal invariance and verify that it allows to reproduce statistical characteristics of Wigner time delays known from independent calculations. We analyze the ensuing two-point statistical measures as e.g. spectral form factor and the number variance. In addition we find the density of complex eigenvalues of real asymmetric matrices generalizing the recent result by Efetov\cite{Efnh}.Comment: 4 page

Nanoparticle labels for pathogen detection through nucleic acid amplification tests

YesMagnetic nanoparticles and surface-enhanced Raman scattering (SERS) active nanoparticles were coated with short chain DNA tags. These were then used to identify a target bacterial DNA sequence. The tags function as primers in a standard PCR with the reverse primers and forward primers on the SERS nanoparticles and magnetic nanoparticles, respectively. During the PCR cycles, a composite nanostructure is formed that is both magnetically responsive and SERS active. After magnetic trapping, the intensity of the SERS signal can be related back to the concentration of the target DNA. A test assay was performed that showed a detection limit (based on the signal to noise ratio) of less than 3 zeptomole (41 pg/L). For comparison, a PCR assay based on the standard SYBR Green method was performed. This used the same primers and target DNA and had a detection limit of 10 attomoles (138 ng/L), 3,000 times less sensitive. The work documents the proof of principle study and shows for the first time the use of SERS-NP labels in the quantification of nucleic acid amplification tests and PCR

Local Fields without Restrictions on the Spectrum of 4-Momentum Operator and Relativistic Lindblad Equation

Quantum theory of Lorentz invariant local scalar fields without restrictions on 4-momentum spectrum is considered. The mass spectrum may be both discrete and continues and the square of mass as well as the energy may be positive or negative. Such fields can exist as part of a hidden matter in the Universe if they interact with ordinary fields very weakly. Generalization of Kallen-Lehmann representation for propagators of these fields is found. The considered generalized fields may violate CPT- invariance. Restrictions on mass-spectrum of CPT-violating fields are found. Local fields that annihilate vacuum state and violate CPT- invariance are constructed in this scope. Correct local relativistic generalization of Lindblad equation for density matrix is written for such fields. This generalization is particulary needed to describe the evolution of quantum system and measurement process in a unique way. Difficulties arising when the field annihilating the vacuum interacts with ordinary fields are discussed.Comment: Latex 23 pages, sent to "Foundations of Physics