Search results for "85"
showing 10 items of 1612 documents
Manipulation of nanoparticles of different shapes inside a scanning electron microscope
2014
In this work polyhedron-like gold and sphere-like silver nanoparticles (NPs) were manipulated on an oxidized Si substrate to study the dependence of the static friction and the contact area on the particle geometry. Measurements were performed inside a scanning electron microscope (SEM) that was equipped with a high-precision XYZ-nanomanipulator. To register the occurring forces a quartz tuning fork (QTF) with a glued sharp probe was used. Contact areas and static friction forces were calculated by using different models and compared with the experimentally measured force. The effect of NP morphology on the nanoscale friction is discussed.
Structural, energetic and kinetic database of catalytic reactions: Benzyl alcohol to benzaldehyde oxidation on MnOx clusters
2021
Abstract Data here reported are connected with the research article “Benzyl Alcohol to Benzaldehyde Oxidation on MnO x Clusters: Unraveling Atomistic Features” Gueci et al. [1] . This work described and discussed structural and energetic results, calculated by Density Functional Theory (DFT). In order to get kinetic information, DFT results were refined by an original approach, which will be shortly described in the following article. The crossed analysis of experimental and computational energetic and kinetic data allowed to (i) reconstruct the complicated lattice that connects the primary and secondary mechanisms of the reaction and (ii) identify alternative process pathways capable of by…
Narrow Band Solid-Liquid Composite Arrangements: Alternative Solutions for Phononic Crystal-Based Liquid Sensors
2019
Periodic elastic composite structures attract great attention. They offer the ability to design artificial properties to advance the control over the propagation of elastic/acoustic waves. In previous work, we drew attention to composite periodic structures comprising liquids. It was shown that the transmission spectrum of the structure, specifically a well-isolated peak, follows the material properties of liquid constituent in a distinct manner. This idea was realized in several liquid sensor concepts that launched the field of phononic crystal liquid sensors. In this work we introduce a novel concept&mdash
Validity of the Wrist-Worn Polar Vantage V2 to Measure Heart Rate and Heart Rate Variability at Rest
2021
Heart rate (HR) and heart rate variability (HRV) can be monitored with wearable devices throughout the day. Resting HRV in particular, reflecting cardiac parasympathetic activity, has been proposed to be a useful marker in the monitoring of health and recovery from training. This study examined the validity of the wrist-based photoplethysmography (PPG) method to measure HR and HRV at rest. Recreationally endurance-trained participants recorded pulse-to-pulse (PP) and RR intervals simultaneously with a PPG-based watch and reference heart rate sensor (HRS) at a laboratory in a supine position (n = 39; 5-min recording) and at home during sleep (n = 29; 4-h recording). In addition, analyses wer…
Application of WGM Resonances to the Measurement of the Temperature Increment of Ho and Ho-Yb Doped Optical Fibers Pumped at 1125 and 975 nm
2021
Optical fiber characterization using whispering gallery mode resonances of the fiber itself has been demonstrated to be a powerful technique. In this work, we exploit the thermal sensitivity of whispering gallery mode resonances to characterize the pump-induced temperature increment in holmium doped and holmium-ytterbium codoped optical fibers. The technique relies on the measurement of the resonances’ wavelength shift due to temperature variation as a function of the pump power. Holmium doped fibers were pumped to the second excited level 5I6 of the Ho3+ ion using a laser diode at 1125 nm and ytterbium-holmium codoped fibers to the 2F5/2 level of the Yb3+ ion by a laser diode at 975 nm. Ou…
Pētera Šmita sarakste ar Jāni Misiņu par latviešu valodas mācīšanu skolā, uzmanības pievēršanu tautas dziesmām, etnogrāfijai, lūgumu atsūtīt grāmatas
1916
P. Šmits vēstulē J. Misiņam izsaka pārdomas par stāvokli Rīgā, jo rit Pirmais pasaules karš, kā arī izsaka pārdomas par sava "Etnografisku rakstu krājuma" nākamā sējuma saturu, latviešu valodas mācīšanu skolā, uzmanības pievēršanu tautas dziesmām, etnogrāfijai. Vēstulē izskan lūgums atsūtīt vairākas grāmatas - kā J. Lautenbaha-Jūsmiņa, tā A. Niedras, Apsīšu Jēkaba, V. Rahmanova, H. Zālītes, E. Dinsberga, G. Merķeļa u.c. autoru, kā arī žurnālu "Druva" iznākušos numurus.
Registration of 3D and Multispectral Data for the Study of Cultural Heritage Surfaces
2013
International audience; We present a technique for the multi-sensor registration of featureless datasets based on the photogrammetric tracking of the acquisition systems in use. This method is developed for the in situ study of cultural heritage objects and is tested by digitizing a small canvas successively with a 3D digitization system and a multispectral camera while simultaneously tracking the acquisition systems with four cameras and using a cubic target frame with a side length of 500 mm. The achieved tracking accuracy is better than 0.03 mm spatially and 0.150 mrad angularly. This allows us to seamlessly register the 3D acquisitions and to project the multispectral acquisitions on th…
Ping-pong configurations and circular orders on free groups
2017
We discuss actions of free groups on the circle with "ping-pong" dynamics; these are dynamics determined by a finite amount of combinatorial data, analogous to Schottky domains or Markov partitions. Using this, we show that the free group $F_n$ admits an isolated circular order if and only if n is even, in stark contrast with the case for linear orders. This answers a question from (Mann, Rivas, 2016). Inspired by work of Alvarez, Barrientos, Filimonov, Kleptsyn, Malicet, Menino and Triestino, we also exhibit examples of "exotic" isolated points in the space of all circular orders on $F_2$. Analogous results are obtained for linear orders on the groups $F_n \times \mathbb{Z}$.
Ontology-based Integration of Web Navigation for Dynamic User Profiling
2015
The development of technology for handling information on a Big Data-scale is a buzzing topic of current research. Indeed, improved techniques for knowledge discovery are crucial for scientific and economic exploitation of large-scale raw data. In research collaboration with an industrial actor, we explore the applicability of ontology-based knowledge extraction and representation for today's biggest source of large-scale data, the Web. The goal is to develop a profiling application, based on the implicit information that every user leaves while navigating the online, with the goal to identify and model preferences and interests in a detailed user profile. This includes the identification o…
A note on Hilbert’s weak nullstellensatz
2015
In this article, through a suitable generalization of the well-known notion of spectrum of an element of an arbitrary normed algebra of Operator Theory, it will be possible to give another simple proof of the Hilbert’s Weak Nullstellensatz.