Using Cumulative Number Densities to Compare Galaxies across Cosmic Time

Comparing galaxies across redshifts at fixed cumulative number density is a popular way to estimate the evolution of specific galaxy populations. This method ignores scatter in mass accretion histories and galaxy-galaxy mergers, which can lead to errors when comparing galaxies over large redshift ranges (Delta z > 1). We use abundance matching in the LCDM paradigm to estimate the median change in number density with redshift and provide a simple fit (+0.16 dex per unit Delta z) for progenitors of z = 0 galaxies. We find that galaxy descendants do not evolve in the same way as galaxy progenitors, largely due to scatter in mass accretion histories. We also provide estimates for the 1-sigma range of number densities corresponding to galaxy progenitors and descendants. Finally, we discuss some limits on number density comparisons, which arise due to difficulties measuring physical quantities (e.g., stellar mass) consistently across redshifts. A public tool to calculate number density evolution for galaxies, as well as approximate halo masses, is available online.Comment: 5 pages, minor revisions to match ApJL accepted version. Code available at: http://code.google.com/p/nd-redshif

The importance of hole concentration in establishing carrier-mediated ferromagnetism in Mn doped Ge

In the present work, we have prepared Mn-doped Ge using different annealing approaches after Mn ion implantation, and obtained samples with hole concentrations ranging from 10^18 to 2.1x10^20 cm^-3, the latter being the highest reported so far. Based on the magnetotransport properties of Mn doped Ge, we argue that the hole concentration is a decisive parameter in establishing carrier-mediated ferromagnetism in magnetic Ge.Comment: 7 pages, 3 figure

Performance Analysis of a 5G Transceiver Implementation for Remote Areas Scenarios

The fifth generation of mobile communication networks will support a large set of new services and applications. One important use case is the remote area coverage for broadband Internet access. This use case ha significant social and economic impact, since a considerable percentage of the global population living in low populated area does not have Internet access and the communication infrastructure in rural areas can be used to improve agribusiness productivity. The aim of this paper is to analyze the performance of a 5G for Remote Areas transceiver, implemented on field programmable gate array based hardware for real-time processing. This transceiver employs the latest digital communication techniques, such as generalized frequency division multiplexing waveform combined with 2 by 2 multiple-input multiple-output diversity scheme and polar channel coding. The performance of the prototype is evaluated regarding its out-of-band emissions and bit error rate under AWGN channel.Comment: Presented in 2018 European Conference on Networks and Communications (EuCNC),18-21 June, 2018, Ljubljana, Sloveni

Comparison of seven portable Raman spectrometers : beryl as a case study

In this paper, a series of beryl varieties with the accent on emeralds was investigated using seven portable Raman spectrometers equipped mainly with 785- and 532-nm excitation lasers. Additionally, one dual system and a new portable sequentially shifted excitation Raman spectrometer were applied. The advantage of using handheld instrumentation for investigations to be carried out outside the laboratory is well documented. For major part of beryls (emeralds and aquamarines), the most intense Raman bands are found at correct positions +/-2 to 4cm(-1) using all the instruments (with the exception of one). Unambiguous identification of beryls is ensured by obtaining the strong characteristic of Raman features (1070 and 686 cm(-1)) of the whole spectrum. Spectroscopic performance and differences existing between the instruments not only from the construction and ergonomic point of view are discussed. All the instruments tested EzRaman-I Dual (Enwave Optronics), RaPort (EnSpectr), FirstGuard (Rigaku), FirstDefender XL and FirstDefender RM (Thermo Scientific), Inspector Raman (Delta Nu) and Bravo (Bruker) can be used for common gemmological and mineralogical work in situ. Two instruments (the RaPort and the sequentially shifted excitation Raman spectrometer Bravo) allow recording excellent quality Raman spectra comparable with laboratory dispersive Raman microspectrometers

Chaos in Symmetric Phase Oscillator Networks

Phase-coupled oscillators serve as paradigmatic models of networks of weakly interacting oscillatory units in physics and biology. The order parameter which quantifies synchronization was so far found to be chaotic only in systems with inhomogeneities. Here we show that even symmetric systems of identical oscillators may not only exhibit chaotic dynamics, but also chaotically fluctuating order parameters. Our findings imply that neither inhomogeneities nor amplitude variations are necessary to obtain chaos, i.e., nonlinear interactions of phases give rise to the necessary instabilities.Comment: 4 pages; Accepted by Physical Review Letter

Non-legislated emissions and PN of two passenger cars with gasoline-butanol blends

Increasing the sustainability of individual transportation and replacing a part of fossil energy in traffic by renewable energy carriers are worldwide important objectives. Bioalcohols are generally recognized as one of very useful alternatives. The global share of bioethanol used for transportation is continuously increasing. Butanol, a four-carbon alcohol, is considered in the last years as an interesting alternative fuel, both for diesel and for gasoline application. Its advantages for engine operation are: good miscibility with gasoline and diesel fuels, higher calorific value than ethanol, lower hygroscopicity, lower corrosivity and possibility of replacing aviation fuels. In the present work, the emissions of two gasoline vehicles – with older and with newer technology – were investigated in dynamic-, stationary and cold start operation