Mycorrhizal feedbacks influence global forest structure and diversity

One mechanism proposed to explain high species diversity in tropical systems is strong negative conspecific density dependence (CDD), which reduces recruitment of juveniles in proximity to conspecific adult plants. Although evidence shows that plant-specific soil pathogens can drive negative CDD, trees also form key mutualisms with mycorrhizal fungi, which may counteract these effects. Across 43 large-scale forest plots worldwide, we tested whether ectomycorrhizal tree species exhibit weaker negative CDD than arbuscular mycorrhizal tree species. We further tested for conmycorrhizal density dependence (CMDD) to test for benefit from shared mutualists. We found that the strength of CDD varies systematically with mycorrhizal type, with ectomycorrhizal tree species exhibiting higher sapling densities with increasing adult densities than arbuscular mycorrhizal tree species. Moreover, we found evidence of positive CMDD for tree species of both mycorrhizal types. Collectively, these findings indicate that mycorrhizal interactions likely play a foundational role in global forest diversity patterns and structure

Precise position sensitive spectroscopy of energetic ions with adapted pixel device

Hybridní pixelový detektor Timepix prokázal, že je velmi užitečným nástrojem v oblasti detekce ionizujícího záření a zobrazovaní. Vykazuje výjimečné schopnosti dovolující přesné měření energie částic, včetně směru jejich dopadu. Tyto schopnosti jsou dány vlastnostmi jako je velmi jemné prostorové rozlišení, či vysoké energetické rozlišeni dovolující registrovat kvantum energie od jednotlivých interagujících částic (fotonů). Spektroskopické schopnosti detektoru mohou být dále umocněny při zpracování analogového signálu ze společné elektrody pixelové matice detektoru. Tato práce se zabývá analýzou, zpracováním a využitím signálu ze společné elektrody pixelového detektoru. Výsledky získané předchozí studií jsou využitý k návrhu precizní jaderné instrumentace, která vyniká oproti ostatním již existujícím řešením díky svým vlastnostem (schopnost souběžné akvizice matic pixelového detektoru v kombinaci se záznamem signálu ze společné elektrody, vysoké spektroskopické rozlišení, vzájemná synchronizace, spouštění kombinovaného měření na základě velikosti energie interagující částice, atd.). Výsledky výzkumu a vývoje otevírají prostor pro nové využití detektoru Timepix na poli sledování těžkých nabitých iontů.NeobhájenoThe hybrid semiconductor pixel detector Timepix has proven to be a powerful tool in radiation detection and radiation imaging. Energy loss and directional sensitivity as well as particle type resolving power are possible by high resolution particle tracking and per-pixel energy and quantum-counting capability. The spectrometric resolving power of the detector can be significantly enhanced by analyzing the analog signal of the detector common sensor electrode (also called the back side pulse). The thesis deals with the study of the backs side pulse signal analysis, processing and its exploitation. The results of the study are used in the subsequent development of the precise instrumentation with enhanced parameters (e.g. simultaneous acquisition of the back side pulse waveforms as well as pixelated matrices of the Timepix detector, high spectroscopic resolution, well-done synchronization, self-trigger capability on base of particle energy, etc.) in comparison to previously available solutions. The results of the research and development open a new application of the Timepix detector for further study of energetic ion

Selected amino acids uptake by microorganisms in soil of differently managed mountain meadows

This work was aimed at determination of the effect of 13 years abandonment of previously long-term mown mountain meadows on uptake of L-glutamic acid (14CO2H[14CH2]2[NH2]14CO2H) and L-alanine (14CH314CH[NH2]14CO2H) by microbial community of Ap horizon (3–13 cm). The study plots has been located near to the experimental stand “Bílý Kříž“ which is located in the Moravian-Silesian Beskids Mountains (N 49°30’17”, E 18°32’28”), on a slope with an elevation of 825–860 m a. s. l. and southeast orientation, and soil classified as an Oxyaquic Hapludalf. The study was performed to test method for measurement of 14C-labelled amino acids uptake by soil microbial community and to increase knowledge on particular processes of N-transformation in soil of these ecosystems. The results obtained in this work showed that 13 years abandonment of mountain meadow did not significantly (P > 0.05) influence rate of glutamic acid or alanine uptake by soil microbial community. Further research including determination of amino acids use by soil microbial biomass with expression of their partitioning between production of new microbial biomass and energy metabolism is necessary

Multichannel coincidence circiut with settable threshold level for ToF AFP detector

The detectors and signal processing chains in the experimental particle physics produce the data in the order of tens GB per hour due to high rate events. The trigger module, as one of the units for signal processing in the Time-of-Flight detector, uses the MCC (Multichannel Coincidence Circuit) for data stream reduction based on the settable threshold level used for the selection of the events related to the ongoing physical experiment. In this paper the MCC design of the circuitry and firmware is described. The performance of the MCC has been verified by measurement and the results proved the proper function of the device. The next generation of the trigger module will be based on this MCC and installed on the LHC particle detector in CERN

j-Pix — a multiplatform acquisition package for Timepix3

We present a newly developed modular and multiplatform acquisition and control package dedicated for high performance Timepix3 pixel detector. The software package was originally developed for operation at ATLAS experiment. Afterwards, it was further extended as an independent package for general purpose measurements and online visualization with Timepix3. Timepix3 detector is a semiconductor detector of 256 x 256 square pixels providing information about energy and time of arrival with time resolution less than 2 ns, which generate a high amount of data to be processed in real time with the data acquisition package. The processed data stream from the detector can be stored on a hard drive and also displayed online using graphical interface with capability to control several number of acquisitions and display measured data using variable modules. Moreover, due to the architecture it can be further extended using external libraries working independently on the software. The architecture of the acquisition package enables online processing and visualization and it is designed as cross-compatible software (supportingWindows, Linux, MacOS, etc.). All peaks in data transmission can be further balanced by several buffers in the pipelined architecture. The size of buffers is configurable and allows scalable tuning according to the available resources. The pipelined architecture exploits all advantages of multithreading

Performance of silicon photomultipliers at low temperature

The performances of silicon photomultipliers with different structures are investigated at low temperature.The first sample is a micro pixel avalanche photodiode with deep buried pixel structure from Zecotek Photonics Inc. The second and third ones are multi-pixel photo counters with a surface pixel design from Hamamatsu Photonics. The influence of temperature on the main parameters of the photodiodes such as photon detection efficiency (PDE), gain, and capacitance was studied in the temperature range from 0C to -120C

Scintillation readout with MAPD array for gamma spectrometer

In this study, we present the gamma-ray detection performance of LYSO, YSO(Ce) and BGO scintillators read out by a 9 ch. micropixel avalanche photodiode (MAPD) array with a high pixel density (PD) and photon detection efficiency (PDE). The array with an active area of 11,5x11,5mm2 was assembled using single MAPDs with an active area of 3,7x3,7mm2. It had a single output signal and was developed for gamma spectroscopy. Breakdown voltage measurements were carried out for each channel, as a result of which the optimal operating voltage for the array was found. The linearity range and energy resolution for each crystal were determined in the energy range from 30 to 1770 keV. The high pixel density of the array allowed to achieve good linearity in the studied energy range

RISEPix - A Timepix-based radiation monitor telescope onboard the RISESAT satellite

Rapid International Scientific Experiment Satellite (RISESAT) is a small Japanese experimental Earth-observing, science and technology demonstration satellite. One of the scientific instruments onboard is a miniature radiation monitor telescope RISEPix with two Timepix detectors, developed and built at the Institute of Experimental and Applied Physics, Czech Technical University in Prague. After its successful launch in January 2019, RISESAT joined two other still operational satellites with our Timepix-based radiation monitors, SATRAM onboard the ESA satellite Proba-V (launched in 2013) and the Czech VZLUSAT-1 cubesat (launched 2017). In this work, we present general technical and scientific details about the RISESAT satellite mission and the RISEPix module, and a basic comparison of space weather monitoring from SATRAM and VZLUSAT-1 radiation monitors

A program for data analysis of rare fission mode processes from neutron-induced and spontaneous fissions

Rare fission mode processes (ternary or quaternary fission) of low-energy and spontaneous fission of heavy nuclei, in which light charged particles are emitted, are the subject of intense experimental and theoretical studies, since these studies can be attributed to one of the main sources of information on the mechanism of nuclear fission. To study these processes, a detection system has been assembled, consisting of three semiconductor ΔE-E telescopes and a silicon detector. In addition, the program has been developed for proceeding experimental data. This paper has been dedicated to the program written on the basis of ROOT software consisting of many scripts to analyze and/or filtrate ternary and quaternary fission particles among different fission events. The program can proceed long collected files in ASCII and binary formats, correlate results from all detectors, give results on particle interaction time, coordinates, particle energy and its types. The performance of the program has been tested to proceed ternary fission data from 252Cf spontaneous fission source

A synchronization and data acquisition system for silicon detectors

A dedicated synchronization bus has been developed and integrated into the FITPix COMBO device. It can be used as Timepix read-out (involving back-side-pulse acquisition) or as a simple spectrometer device—Spectrig (when an external single pad sensor is connected, e.g. Δ E detector). The synchronization bus permits the implementation of a system of up to 32 distinct devices running in clock locked mode while the absolute value of the timestamp is distributed to all devices in the system. Any combination of Timepix or spectrometer devices (up to 32) can be connected-up to create a final measurement set-up. The synchronization bus has also been designed to control a trigger signal and busy signal to allow an effective filtration of unpaired events when coincidence measurement is performed. The system has been tested with a Δ E− E telescope consisting of a thin detector and Timepix. The thin detector has been used for Δ E and the Timepix detector for E measurements. The Δ E detector has an area of 10×10 mm2 and a thickness of 12 μm with non-uniformity of 8%. The area and thickness of Timepix are 14×14 mm2 and 300 μm, respectively. The detection system can provide simultaneous information about position, energy, time and type of registered particles with high synchronization accuracy. Test measurements have been carried out with an alpha particle source (Ra-226) in a vacuum and the results of these measurements are presented in this paper