Estimating Phase Velocity and Attenuation of Guided Waves in Acoustic Logging Data

Phase velocity and attenuation of guided waves have been estimated from multireceiver, full waveform, acoustic logging data using the extended Prony's method. Since a formation affects velocity and attenuation, estimating these quantities is important in evaluating the formation properties. The estimation is performed using an array processing technique which requires two steps: (1) the traces for all receivers are transformed into the frequency domain, and (2) for each frequency the extended Prony's method is used to determine the presence of a guided wave propagating past the array of receivers. The guided wave properties estimated by the Prony's method include amplitude, attenuation, and phase change which is related to phase velocity. An important assumption in this array processing technique is that the formation, borehole fluid, and tool are homogeneous along the receiving array. For synthetic data, the phase velocities and attenuation of the tube wave and two modes of the pseudo-Rayleigh wave are accurately estimated over many frequencies, with the exception that the low amplitude of the second mode causes its attenuation estimate to be somewhat less accurate. For laboratory data, very good estimates of the phase velocities of the tube wave and three modes of the pseudo-Rayleigh wave are obtained. Since the materials used in the laboratory experiment had very large quality factors, the attenuation could not be estimated. For field data, the dispersion of the tube wave and the velocity of the pseudo-Rayleigh wave at its cutoff are very close to those predicted by another, independent method. Accurate attenuation estimates could not be made because the data are noisy and consist of only eight traces.Massachusetts Institute of Technology. Full Waveform Acoustic Logging Consortiu

bak deletion stimulates gastric epithelial proliferation and enhances Helicobacter felis-induced gastric atrophy and dysplasia in mice

Helicobacter infection causes a chronic superficial gastritis that in some cases progresses via atrophic gastritis to adenocarcinoma. Proapoptotic bak has been shown to regulate radiation-induced apoptosis in the stomach and colon and also susceptibility to colorectal carcinogenesis in vivo. Therefore we investigated the gastric mucosal pathology following H. felis infection in bak-null mice at 6 or 48 wk postinfection. Primary gastric gland culture from bak-null mice was also used to assess the effects of bak deletion on IFN-γ-, TNF-α-, or IL-1β-induced apoptosis. bak-null gastric corpus glands were longer, had increased epithelial Ki-67 expression, and contained fewer parietal and enteroendocrine cells compared with the wild type (wt). In wt mice, bak was expressed at the luminal surface of gastric corpus glands, and this increased 2 wk post-H. felis infection. Apoptotic cell numbers were decreased in bak-null corpus 6 and 48 wk following infection and in primary gland cultures following cytokine administration. Increased gastric epithelial Ki-67 labeling index was observed in C57BL/6 mice after H. felis infection, whereas no such increase was detected in bak-null mice. More severe gastric atrophy was observed in bak-null compared with C57BL/6 mice 6 and 48 wk postinfection, and 76% of bak-null compared with 25% of C57BL/6 mice showed evidence of gastric dysplasia following long-term infection. Collectively, bak therefore regulates gastric epithelial cell apoptosis, proliferation, differentiation, mucosal thickness, and susceptibility to gastric atrophy and dysplasia following H. felis infection

Velocity Analysis of Multi-Receiver Full Waveform Acoustic Logging Data In Open and Cased Holes

Average semblance and maximum-likelihood spectral analyses are applied to synthetic and field full waveform acoustic logging data to determine formation velocities. Of particular interest is the ability of these methods to resolve the P and shear/pseudo Rayleigh arrivals in data from poorly-bonded cased boreholes. In synthetic open-hole data the velocity analyses yield results within 4% of the true velocities. Results from synthetic well-bonded cased hole data are generally as good as those from the open hole data. However, if the formation P-wave velocity is within roughly 10% of the plate velocity of the steel pipe (about 5.3-5.5 km/s), then there may be a resonance effect that appears to slow down the P wave slightly (on the order of 6%). For cased-hole models with no steel/cement bonding (the free-pipe situation), the measured P-wave velocities are typically 6 to 8% less than the actual formation velocities. If the formation S-wave velocity is greater than about 2.5 km/s, the S-wave velocity estimate may also be 6 to 8% low. Furthermore, increasing the thickness of either the cement layer or the fluid layer between the pipe and the cement further decreases the formation velocity estimates. Also, if the P-wave velocity is within roughly 15% of the velocity of the steel arrival, the P wave may not be resolved by the semblance method unless the data is first low-pass filtered. Initial tests show that this filtering process may adversely affect the final P-wave velocity estimate, but the details of this type of approach have not been studied. The P wave is resolved. by spectral analysis of the original, unfiltered data. For cased-hole models with no cement/formation bonding (the unbonded-casing situation), formation S-wave velocities are estimated to within 3% relative error, and the formation P-wave velocity is estimated to within 2% error in a slow formation. However, for P-wave velocities between 3.4 km/s and 5.94 km/a, the P wave cannot be resolved by spectral analysis, and it is resolved by the semblance method only in the model with the low velocity (3.4 km/s).Massachusetts Institute of Technology. Full Waveform Acoustic Logging ConsortiumPhillips Petroleum Fellowshi

Evaluation of nonmetallic thermal protection materials for the manned space shuttle. Volume 1, task 1: Assessment of technical risks associated with utilization of nonmetallic thermal protection system

Technical problems of design and flight qualification of the proposed classes of surface insulation materials and leading edge materials were reviewed. A screening test plan, a preliminary design data test plan and a design data test plan were outlined. This program defined the apparent critical differences between the surface insulators and the leading edge materials, structuring specialized screening test plans for each of these two classes of materials. Unique testing techniques were shown to be important in evaluating the structural interaction aspects of the surface insulators and a separate task was defined to validate the test plan. In addition, a compilation was made of available information on proposed material (including metallic TPS), previous shuttle programs, pertinent test procedures, and other national programs of merit. This material was collected and summarized in an informally structured workbook

Radio-frequency powered glow discharge device and method with high voltage interface

A high voltage accelerating potential, which is supplied by a high voltage direct current power supply, is applied to the electrically conducting interior wall of an RF powered glow discharge cell. The RF power supply desirably is electrically grounded, and the conductor carrying the RF power to the sample held by the probe is desirably shielded completely excepting only the conductor\u27s terminal point of contact with the sample. The high voltage DC accelerating potential is not supplied to the sample. A high voltage capacitance is electrically connected in series between the sample on the one hand and the RF power supply and an impedance matching network on the other hand. The high voltage capacitance isolates the high DC voltage from the RF electronics, while the RF potential is passed across the high voltage capacitance to the plasma. An inductor protects at least the RF power supply, and desirably the impedance matching network as well, from a short that might occur across the high voltage capacitance. The discharge cell and the probe which holds the sample are configured and disposed to prevent the probe\u27s components, which are maintained at ground potential, from bridging between the relatively low vacuum region in communication with the glow discharge maintained within the cell on the one hand, and the relatively high vacuum region surrounding the probe and cell on the other hand. The probe and cell also are configured and disposed to prevent the probe\u27s components from electrically shorting the cell\u27s components

Oral iron exacerbates colitis and influences the intestinal microbiome

Inflammatory bowel disease (IBD) is associated with anaemia and oral iron replacement to correct this can be problematic, intensifying inflammation and tissue damage. The intestinal microbiota also plays a key role in the pathogenesis of IBD, and iron supplementation likely influences gut bacterial diversity in patients with IBD. Here, we assessed the impact of dietary iron, using chow diets containing either 100, 200 or 400 ppm, fed ad libitum to adult female C57BL/6 mice in the presence or absence of colitis induced using dextran sulfate sodium (DSS), on (i) clinical and histological severity of acute DSS-induced colitis, and (ii) faecal microbial diversity, as assessed by sequencing the V4 region of 16S rRNA. Increasing or decreasing dietary iron concentration from the standard 200 ppm exacerbated both clinical and histological severity of DSS-induced colitis. DSS-treated mice provided only half the standard levels of iron ad libitum (i.e. chow containing 100 ppm iron) lost more body weight than those receiving double the amount of standard iron (i.e. 400 ppm); p<0.01. Faecal calprotectin levels were significantly increased in the presence of colitis in those consuming 100 ppm iron at day 8 (5.94-fold) versus day-10 group (4.14-fold) (p<0.05), and for the 400 ppm day-8 group (8.17-fold) versus day-10 group (4.44-fold) (p<0.001). In the presence of colitis, dietary iron at 400 ppm resulted in a significant reduction in faecal abundance of Firmicutes and Bacteroidetes, and increase of Proteobacteria, changes which were not observed with lower dietary intake of iron at 100 ppm. Overall, altering dietary iron intake exacerbated DSS-induced colitis; increasing the iron content of the diet also led to changes in intestinal bacteria diversity and composition after colitis was induced with DSS

Trinity University\u27s Summer Bridge Program: Navigating the Changing Demographics in Higher Education

Our article is divided into five sections. First, our study explores the demographic, economic, and cultural changes influencing higher education. We also explain the tangible and intangible benefits of a college education for first-generation, underrepresented students (FGUS). Second, we provide a brief discussion of the history of Trinity University and our Summer Bridge program. Third, our study describes our Summer Bridge program. Fourth, the data we collected examines how our Summer Bridge students’ grades and retention rates compare to our other first-year students. And, fifth, our article concludes with a discussion of future directions for our Summer Bridge program and how it may apply to other higher educational institutions. In particular, we offer recommendations for other student affairs professionals who also will be experiencing an increase in first-generation, underrepresented students

Why won’t it Stick? Positive Psychology and Positive Education

Following the launch of the positive psychology movement teachers and educators emerged as early adopters of this fledgling science. This approach was called positive education. It describes scientifically validated programs from positive psychology, taught in schools, that have an impact on student well-being. The growing body of evidence about the reach of positive psychology has formed a convincing case to consider well-being an operational goal for educational systems. It is argued that this goal is pivotal and should be pursued in the same way in which we develop strategies to harness academic growth, school retention rates, and student engagement. National education policies can have widespread influence at the grassroots level on school improvement, good quality of classroom teaching and learning, student performance, creating confident and creative individuals and active and informed citizens, but not necessarily on the preventative skills for lifelong well-being. In this article I take stock on the positive education movement. Three approaches to positive education are identified and eight hurdles to the field are noted as reasons why positive education won’t stick in policy. Then, I reflect on two case studies: a Well-being Summit and Round Table held at Wellington College and No. 10 Downing Street and Dr. Martin Seligman’s role as Adelaide’s Thinker in Residence as examples of grass-roots initiatives in well-being. Finally, six strategies are suggested for researchers and practitioners to grow the field. Last, I argued that until research centers focus on the development of common definitions of the key terms underpinning positive psychology, positive education and well-being the impact of the movement will be limited to a handful of institutions as models of best practice

Socio-ecological influences on adolescent dietary typologies

Background: Dietary behaviours of adolescence are concerning, and this may impact long-term well-being. Aim: This study examined the socio-ecological determinants of dietary behaviours in a national prospective cohort study of English adolescents. Methods: Latent class analysis was used to identify the typologies of eight dietary behaviours: fruit, vegetable, breakfast, sugar-sweetened beverages, artificial-sweetened beverages, fast-food, bread, and milk from 7402 adolescents aged 13-15 years (mean 13.8 ± 0.45 years) (50.3% female and 71.3% white ethnicity) participating in the U.K. Millennium Cohort Study (sixth survey). Multinomial logistic regression and path analysis predicted associations between personal characteristics, individual, influential others, social environment and physical environment determinants and three distinct diet typologies: (1) healthy, (2) less-healthy and (3) mixed, (reference category = mixed). Results: Within Path analysis, the magnitudes of coefficients were small to moderate suggesting a relatively weak relationship between the variables. Model 1 reported adolescents within the less-healthy compared to mixed typology had lower levels of physical activity (β = 0.074, 95% CI = -0.115, -0.033), and have siblings (β = 0.246, 95% CI = 0.105, 0.387). Model 2 reported adolescents within the healthy compared to mixed typology had lower screen time (β = 0.104, 95% CI = 0.067, 0.141), and lower social media usage (β = 0.035, 95% CI = 0.024, 0.046). Conclusion: This study highlights the importance of considering multiple dietary determinants. These findings are likely to be useful in supporting the development of multi-faceted interventions. They emphasise the need to move away from investigating silo behaviours on individual diet components and a step towards more systems thinking to improve adolescent eating behaviours