Hybrid 3D visualisations of archaeological sites: dynamic 3D visualisations of Harris Matrix data for rescue town excavations, Gdansk / Szafarnia site, Poland

In our solution a rich database model is used to represent stratigraphic data. This allows for the easy selection of ranges and types of data for visualisation. Using a simple data management application, several archaeologists can easily share the same dataset, enabling group work. Using a database management system for data storage instantly gives numerous benefits, which, among others, include efficient data representation, robust data access, transactional processing and data integrity constraints (verification of possible values, their constraints, their relationships, etc.). A prototype of an X-VR based Harris Matrix visualisation system has been developed. 3D diagrams can be displayed using standard VRML plug-ins to internet browsers without installing any specific software. The system has been tested on data from Gdańsk town excavations – Szafarnia (Schaferei) site

Bolometric technique for high-resolution broadband microwave spectroscopy of ultra-low-loss samples

A novel low temperature bolometric method has been devised and implemented for high-precision measurements of the microwave surface resistance of small single-crystal platelet samples having very low absorption, as a continuous function of frequency. The key to the success of this non-resonant method is the in-situ use of a normal metal reference sample that calibrates the absolute rf field strength. The sample temperature can be controlled independently of the 1.2 K liquid helium bath, allowing for measurements of the temperature evolution of the absorption. However, the instrument's sensitivity decreases at higher temperatures, placing a limit on the useful temperature range. Using this method, the minimum detectable power at 1.3 K is 1.5 pW, corresponding to a surface resistance sensitivity of $\approx$1 $\mu\Omega$ for a typical 1 mm$\times$1 mm platelet sample.Comment: 13 pages, 12 figures, submitted to Review of Scientific Instrument

Phenomenology of a-axis and b-axis charge dynamics from microwave spectroscopy of highly ordered YBa2Cu3O6.50 and YBa2Cu3O6.993

Extensive measurements of the microwave conductivity of highly pure and oxygen-ordered \YBCO single crystals have been performed as a means of exploring the intrinsic charge dynamics of a d-wave superconductor. Broadband and fixed-frequency microwave apparatus together provide a very clear picture of the electrodynamics of the superconducting condensate and its thermally excited nodal quasiparticles. The measurements reveal the existence of very long-lived excitations deep in the superconducting state, as evidenced by sharp cusp-like conductivity spectra with widths that fall well within our experimental bandwidth. We present a phenomenological model of the microwave conductivity that captures the physics of energy-dependent quasiparticle dynamics in a d-wave superconductor which, in turn, allows us to examine the scattering rate and oscillator strength of the thermally excited quasiparticles as functions of temperature. Our results are in close agreement with the Ferrell-Glover-Tinkham sum rule, giving confidence in both our experiments and the phenomenological model. Separate experiments for currents along the $\hat a$ and $\hat b$ directions of detwinned crystals allow us to isolate the role of the CuO chain layers in \YBCO, and a model is presented that incorporates both one-dimensional conduction from the chain electrons and two-dimensional transport associated with the \cuplane plane layers.Comment: 17 pages, 13 figure

Population-level analysis of migratory phenology using genomic data in a migratory songbird

2022 Spring.Includes bibliographical references.The timing of spring migration for Nearctic-Neotropical birds is key for maximizing access to seasonal resources, such as food or territory on the breeding grounds, while minimizing risk of exposure to winter conditions. Many factors, including sex, weather, energetic condition, and food availability influence migration timing. However, the methods for disentangling within and between population drivers of migratory timing have historically been limited by challenges associated with identifying the breeding location of migrants passing through stop-over sites. For example, spring phenology hypotheses predict that the timing of migration will be driven by the date of spring onset at the breeding grounds, but spring onset often co-varies with distance to breeding site, making it difficult to disentangle the relative roles of each. Here, we utilize genomic data to identify the breeding ground of origin for over one thousand Common Yellowthroats (Geothlypas trichas) collected at key migratory stopover points to test the relative roles of sex, migration distance, and date of spring onset in driving migratory timing. We found different relationships for analyses at the species and population level. We conclude that while sex, estimated migration distance, genetic population, and breeding ground phenology are all highly significant predictors of migratory timing across the species, the relative importance each factor differs among genetically distinct populations and from the species-level pattern. Our results highlight the importance of including population-level differences when attempting to understand the multitude of factors that regulate migratory timing

Identification of Belowground Woody Structures Using Molecular Biomarkers

Within the last two decades substantial progress has been made in understanding seed bank dynamics and the contribution of the soil seed bank to a post-disturbance plant community. There has been relatively little progress, however, in understanding perennial bud bank dynamics and the contribution of the soil bud bank to secondary succession. This lack of information is due primarily to the inability to reliably identify roots, rhizomes, and lignotubers that lie dormant beneath the soil surface. This scientific investigation, therefore, addressed the issue of identification of belowground woody structures. The first objective was to develop a methodology that utilizes molecular tools to reliably identify woody plant species from subsoil tissue samples. The second objective was to create a key in which molecular markers serve as criteria for identification and differentiation of selected tree and shrub species common to the mountains of northeast Oregon and southeast Washington. Application of restricted fragment length polymorphism (RFLP) analysis on polymerase chain reaction (PCR)-amplified rbcL gene products proved to be a reliable method to identify and differentiate 15 plants to the genus level. Two restriction enzymes, DPN II and Hha I, cut (or do not cut) the PCR-rbcL product into one to six fragments. Fragment number and length are used to develop an identification key. Plants not analyzed in this key may share the same banding patterns , resulting in a false-positive identification of unknowns. Future research needs and management implications are discussed

Modeling and measuring the non-ideal characteristics of transmission lines

We describe a simple method to experimentally determine the frequency dependencies of the per-unit-length resistance and conductance of transmission lines. The experiment is intended as a supplement to the classic measurement of the transient response of a transmission line to a voltage step or pulse. In the transient experiment, an ideal (lossless) model of the transmission line is used to determine the characteristic impedance and signal propagation speed. In our experiment, the insertion losses of various coaxial cables are measured as a function of frequency from 1 to 2000 MHz. A full distributed circuit model of the transmission line that includes both conductor and dielectric losses is needed to fit the frequency dependence of the measured insertion losses. Our model assumes physically-sensible frequency dependencies for the per-unit-length resistance and conductance that are determined by the geometry of the coaxial transmission lines used in the measurements.Comment: 10 pages, 6 figure

Magnetization Dynamics in the Lanthanide Metal Gadolinium

In this thesis we investigate the rare-earth metal Gd aiming to gain more insight into the complex interplay of physical processes leading to optically induced ultrafast magnetization dynamics. Using X-ray magnetic circular dichroism (XMCD) we study the magnetization dynamics in Gd over a wide range of time scales and pump laser fluences, while using photoemission spectroscopy (PES) we focus on the first 100 fs of the dynamics showing an increase in exchange splitting of the 5d6s bulk bands. Moreover, we analyze oscillations in the kinetic energy of the photoemitted electrons for negative pump-probe delays in our PES data. Using XMCD in reflection we find a two-step demagnetization on sub-ps and tens of ps time scales with a remagnetization on a hundred ps time scale for various pump laser fluences. An extended version of the microscopic three-temperature model (M3TM) captures the dynamics of the whole data set and suggests Elliott-Yafet-type spin-flip scattering to play a dominant role in the 100 fs to ns magnetization dynamics in Gd. On the fast time scale the demagnetization magnitude depends exponentially on the pump laser fluence implying that a complete demagnetization on that time scale in pure Gd is not physically possible. Results for varying pump photon energies indicate an influence of the initial hot electron distribution on the following dynamics, where lower pump photon energies cause a weaker demagnetization in the early sub-ps dynamics. Our PES study reveals new results particularly in the first 100 fs, where the majority-spin bulk band reacts directly to laser excitation and is not delayed as found in literature. Shifts in the minority- and majority-spin bulk band binding energies lead to a surprising increase in exchange splitting of the 5d6s valence bands in Gd for a few dozen fs after laser excitation indicating an increase in magnetization. Concurrently, the majority-spin bulk and surface states shift in opposing directions despite the same spin polarization. We find optically induced spin transfer (OISTR) between the surface and bulk states in Gd likely to account for this phenomenon. At negative pump-probe delays we observe oscillations in the kinetic energy of photoemitted electrons, a phenomenon explained in literature by ponderomotive acceleration by a transient grating formed by the interference of the incoming and reflected pump laser pulse. We observe a strong enhancement of the oscillation amplitudes on Gd in accordance with the model. We find similar oscillations on W and model parameters show the expected pump photon energy dependence. However, we see different amplitudes for electrons emitted out of different states in W with only slightly different kinetic energy, an unexpected result since photoemitted, free electrons subject to the same potential should experience the same force