Crustal deformation at very long baseline interferometry sites due to seasonal air-mass and ground water variations

The seasonal deformation normal to the Earth's surface was calculated at stations involved or interested in very long baseline interferometry (VLBI) geodesy and at hypothetical sites in Australia and Brazil using global atmospheric pressure data, values for groundwater storage, and load Love numbers deduced from current Earth models. It was found that the annual range of deformation approached the centimeter level measuring potential of the VLBI technqiue at Greenbank, Haystack, and the Brazil site

The Superconducting Gravimeter CD-034 at Moxa Observatory: More than 20 Years of Scientific Experience and a Reanimation

In this work, advanced methods and processing schemes for the analysis of data from a Superconducting Gravimeter (SG) will be introduced and their relevance on acquired data proved. The SG CD-034 was installed on Easter of 1999 in the Geodynamic Observatory Moxa of the Friedrich Schiller University Jena, Germany. Initially, the quality of the recorded data was examined, spectra for the detection of the parasitic modes were calculated and the calibration values for the two sensors were determined. Ever since very high-quality gravity data of this SG and most of the other worldwide SGs were made available through the storage archive of the Global Geodynamics Project (GGP later changed to IGETS, International Geodynamics and Earth Tide Service) for global scientific investigations at that time. SG’s such as the one in Moxa (Germany) still deliver significant scientific value for global gravitational field studies as well as for regional/local studies which will be shortly reviewed. Examples are the detection of polar motion, the influence of continental water loading in general and in particular river basin loads, the gravimetric effect of North Sea storm surges and the study of hydro-gravimetric signals, which could be compared with satellite observations and global hydraulic models. The long-term, low-noise operation of complex SG’s requires some effort on maintenance. In order to evaluate the correct operation of the SG, new data processing steps were introduced to assist in the analysis of the data in case of issues with the instrumentation. For example, in 2012/2013 and 2020/2021 severe interference in the gravimeter electronics in Moxa led to a significant loss of data. In both cases, however, the cause could be determined, and the corresponding electronic components renewed. Since July 2021, the SG in Moxa registers again with high data quality comparable or slightly better than before the incident. Initial tests and tidal analyses confirm the validity of the old calibration factors, and the authors now look forward to the re-established long-term recording with excitement and confidence

Exploring Students\u27 Perceptions of Academically Based Living-Learning Communities

This qualitative study employed focus group interviews to explore students\u27 perceptions of three well established academically based living-learning communities at a large, land-grant university in the Midwest. Three themes emerged that illustrated students\u27 perceptions of a culture that promoted seamless learning, a scholarly environment, and an ethos of relatedness among faculty, staff, and peers. Implications for practice and future research are discussed

Results of the Australian geodetic VLBI experiment

The 250-2500 km baseline vectors between radio telescopes located at Tidbinbilla (DSS43) near Canberra, Parkes, Fleurs (X3) near Sydney, Hobart and Alice Springs were determined from radio interferometric observations of extragalactic sources. The observations were made during two 24-hour sessions on 26 April and 3 May 1982, and one 12-hour night-time session on 28 April 1982. The 275 km Tidbinbilla - Parkes baseline was measured with an accuracy of plus or minus 6 cm. The remaining baselines were measured with accuracies ranging from 15 cm to 6 m. The higher accuracies were achieved for the better instrumented sites of Tidbinbilla, Parkes and Fleurs. The data reduction technique and results of the experiment are discussed

Microbial transformation of elements: the case of arsenic and selenium

Microbial activity is responsible for the transformation of at least one third of the elements in the periodic table. These transformations are the result of assimilatory, dissimilatory, or detoxification processes and form the cornerstones of many biogeochemical cycles. Arsenic and selenium are two elements whose roles in microbial ecology have only recently been recognized. Known as “essential toxins”, they are required in trace amounts for growth and metabolism but are toxic at elevated concentrations. Arsenic is used as an osmolite in some marine organisms while selenium is required as selenocysteine (i.e. the twenty-first amino acid) or as a ligand to metal in some enzymes (e.g. FeNiSe hydrogenase). Arsenic resistance involves a small-molecularweight arsenate reductase (ArsC). The use of arsenic and selenium oxyanions for energy is widespread in prokaryotes with representative organisms from the Crenarchaeota, thermophilic bacteria, low and high G+C gram-positive bacteria, and Proteobacteria. Recent studies have shown that both elements are actively cycled and play a significant role in carbon mineralization in certain environments. The occurrence of multiple mechanisms involving different enzymes for arsenic and selenium transformation indicates several different evolutionary pathways (e.g. convergence and lateral gene transfer) and underscores the environmental significance and selective impact in microbial evolution of these two elements

Comparison of Simulator Wear Measured by Gravimetric vs Optical Surface Methods for Two Million Cycles

Understanding wear mechanisms are key for better implants Critical to the success of the simulation Small amount of metal wear can have catastrophic effects in the patient such as heavy metal poisoning or deterioration of the bone/implant interface leading to implant failure Difficult to measure in heavy hard-on-hard implants (metal-on-metal or ceramic-on-ceramic) May have only fractions of a milligram of wear on a 200 g component At the limit of detection of even high-end balances when the component is 200 g and the change in weight is on the order of 0.000 1 grams Here we compare the standard gravimetric wear estimate with A non-contact 3D optical profiling method at each weighing stop A coordinate measuring machine (CMM) at the beginning and end of the ru