Elastic Laboratory Measurements and Modeling of Saturated Basalts

Understanding the elastic behavior of basalt is important to seismically monitor volcanoes, subsea basalts, and carbon sequestration in basalt. We estimate the elastic properties of basalt samples from the Snake River Plain, Idaho, at ultrasonic (0.8 MHz) and seismic (2–300 Hz) frequencies. To test the sensitivity of seismic waves to the fluid content in the pore structure, measurements are performed at three saturation conditions: saturated with liquid CO2, water, and dry. When CO2 replaces water, the P-wave velocity drops, on average, by 10%. Vesicles and cracks, observed in the rock microstructure, control the relaxation of pore-fluid pressures in the rock as a wave propagates. The bulk and shear moduli of basalts saturated with liquid CO2 are not frequency dependent, suggesting that fluid pore pressures are in equilibrium between 2 Hz and 0.8 MHz. However, when samples are water saturated, the bulk modulus of the rock is frequency dependent. Modeling with Gassmann\u27s equations predicts the measured saturated rock bulk modulus for all fluids for frequencies below 20 Hz but underpredicts the water-saturated basalt bulk modulus for frequencies greater than 20 Hz. The most likely reason is that the pore-fluid pressures are unrelaxed. Instead, the ultrasonic frequency rock moduli are modeled with high-frequency elastic theories of squirt flow and Kuster–Toksöz (KT). Although KT\u27s model is based on idealized pore shapes, a combination of spheres (vesicles) and penny-shaped cracks (fractures) interpreted and quantified from petrographical data predicts the ultrasonic dry and saturated rock moduli for the measured basalts

Perceptions of an older patient on the role of the family doctor in health promotion : a qualitative case study

Introduction: Health promotion and disease prevention are important aspects of primary health care. However, limited data are available concerning the opinions of older patients towards the respective services offered by family doctors. The aim of the present study was to evaluate an older patient's perception of the role of the family doctor in promoting his health, and identify those components that are difficult to examine in quantitative research. Methods: A qualitative case study of an 80-year-old man using an in-depth interview was carried out. The interview transcript was analyzed thematically. Our patient was an 80-year-old university-educated man, with stable social and financial circumstances, living with his wife. He had retired early on grounds of ill health (tuberculosis) and had received a disability pension prior to formal retirement. At the time of the interview, his medical problems included mild prostatic hypertrophy, scoliosis and hypertension. He considered his health status to be satisfactory. He had changed family doctor five years prior to the interview, as he had been dissatisfied with the care provided. Results: We found that our patient expected the family doctor to be aware of, and to discuss, the following issues: physical activity, diet, management of stress and mental health, use of alcohol and tobacco, personal hygiene, health screening, use of medication, and social activity. At the same time, our patient perceived the doctor's role as supplementary to his own in terms of the appraisal and maintenance of his health. Conclusions: Our findings provide evidence of what is important in the promotion of health among older people

Noncontacting Benchtop Measurements of the Elastic Properties of Shales

We evaluated a laser-based noncontacting method to measure the elastic anisotropy of horizontal shale cores. Whereas conventional transducer data contained an ambiguity between phase and group velocity measurements, small laser source and receiver footprints on typical core samples ensured group velocity information in our laboratory measurements. With a single dense acquisition of group velocity versus group angle on a horizontal core, we estimated the elastic constants C11, C33, and C55 directly from ultrasonic waveforms, and C13 from a least-squares fit of modeled to measured group velocities. The observed significant P-wave velocity and attenuation anisotropy in these dry shales were almost surely exaggerated by delamination of clay platelets and microfracturing, but provided an illustration of the new laboratory measurement technique. Although challenges lay ahead to measure preserved shales at in situ conditions in the lab, we evaluated the fundamental advantages of the proposed method over conventional transducer measurements

Changes in Elastic Wave Velocity and Rock Microstructure Due to Basalt-CO\u3csub\u3e2\u3c/sub\u3e-Water Reactions

The chemical interaction between carbon dioxide, water, and basalt is a common process in the earth, which results in the dissolution of primary minerals that later precipitate as alteration minerals. This occurs naturally in volcanic settings, but more recently basalts have been suggested as reservoirs for sequestration of anthropogenic CO2. In both the natural and man-made cases, rock-fluid reactions lead to the precipitation of carbonates. Here, we quantify changes in ultrasonic wave speeds, associated with changes in the frame of whole-rock basalts, as CO2 and basalt react. After 30weeks of reactions and carbonate precipitation, the ultrasonic wave speed in dry basalt samples increases between 4% and 20% and permeability is reduced by up to an order of magnitude. However, porosity decreases only by 2% to 3%. The correlation between significant changes in wave speed and permeability indicates that a precipitate is developing in fractures and compliant pores. Thin sections, XRF-loss on ignition, and water chemistry confirm this observation. This means time-lapse seismic monitoring of a CO2-water-basalt system cannot assume invariance of the rock frame, as typically done in fluid substitution models. We conclude that secondary mineral precipitation causes a measurable change in the velocities of elastic waves in basalt-water-CO2 systems, suggesting that seismic waves could be used to remotely monitor future CO2 injection sites. Although monitoring these reactions in the field with seismic waves might be complicated due to the heterogeneous nature of basalt, quantifying the elastic velocity changes associated with rock alteration in a controlled laboratory experiment forms an important step toward field-scale seismic monitoring

A Feasibility Study of Time-Lapse Seismic Monitoring of CO\u3csub\u3e2\u3c/sub\u3e Sequestration in a Layered Basalt Reservoir

We investigate the potential of scattered seismic waves to remotely sense geological sequestration of CO2 in basalt. Numerical studies in horizontally layered models suggest that strong scattering quickly complicates the wave fields, but also provides a sensitive tool to monitor physical changes in and around the reservoir. These results go hand-in-hand with recent laboratory work and rock-physics modeling that has shown significant changes in the seismic properties of a reservoir undergoing CO2 sequestration, due to fluid substitution and mineral precipitation

Important characteristics of an entrepreneur in relation to risk taking: Czech Republic case study

New businesses arising at the market usually operate in the sector of small and medium-sized enterprises and account for a significant part of the whole global economy. Not only the success of a start-up company, but also its sequel within the SME sector are significantly influenced by entrepreneur's personality. The aim of this article is to explore the attitude to financial risk in relation to sociodemographic characteristics (gender, education, age) and the most important personality traits of entrepreneurs (risk-taking, decisiveness, optimism). We have analyzed the data collected from 1141 respondents during 2015 in 14 regions of Czech Republic. Empirical results of our paper show that the researched entrepreneurs rather can't manage financial risks in their firms regardless their gender, education, age or personality traits. Most entrepreneurs consider the importance of financial risk to increase during the crisis period. These opinions differed in relation to age, gender and such personality traits as "decisiveness" and "optimism". The results also show that the entrepreneurs try to minimise the financial risk through building-up reserves in relation to such qualities as "risk-taking" and "decisiveness" in comparison to a rather negative attitude to "optimism". © Foundation of International Studies, 2017 & CSR, 2017

Over-expression of Arabidopsis AtCHR23 chromatin remodeling ATPase results in increased variability of growth and gene expression

Plants are sessile organisms that deal with their -sometimes adverse- environment in well-regulated ways. Chromatin remodeling involving SWI/SNF2-type ATPases is thought to be an important epigenetic mechanism for the regulation of gene expression in different developmental programs and for integrating these programs with the response to environmental signals. In this study, we report on the role of chromatin remodeling in Arabidopsis with respect to the variability of growth and gene expression in relationship to environmental conditions