OALib Journal期刊

ISSN: 2333-9721




2020 ( 73 )

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匹配條件: “ P Wall” ,找到相關結果約201114條。
Flaw Detection Capability and Sensitivity in the Inspection of Nuclear Containment Liner and Shell Mock-Ups Utilizing a Magnetostrictive Sensor (MsS) Guided Wave UT Technique  [PDF]
Brian P. Hohmann, Joseph P. Crosson, Thomas C. Esselman, James J. Wall, Mike Quarry, Luke Breon
Journal of Modern Physics (JMP) , 2014, DOI: 10.4236/jmp.2014.513119

This paper describes the results of a project on the inspection of visually inaccessible areas of nuclear containment liners and shells via the advanced Magnetostrictive sensor (MsS) Guided Wave (GW) nondestructive inspection technique. Full scale mockups that simulated shell and liner regions of interest in the containment of both a Pressurized Water Reactor (PWR) and Boiling Water Reactor (BWR) were constructed. Inspections were performed on the mock-ups in three stages to discern the signal attenuation caused by flaws and caused by concrete in the structures. The effect of concrete being in close proximity to the liner and shell was determined, and the capability to detect and size flaws via this GW technique was evaluated.

Cross-pollination of research findings, although uncommon, may accelerate discovery of human disease genes
Duda Marlena,Nelson Tristan,Wall Dennis P
BMC Medical Genetics , 2012, DOI: 10.1186/1471-2350-13-114
Abstract: Background Technological leaps in genome sequencing have resulted in a surge in discovery of human disease genes. These discoveries have led to increased clarity on the molecular pathology of disease and have also demonstrated considerable overlap in the genetic roots of human diseases. In light of this large genetic overlap, we tested whether cross-disease research approaches lead to faster, more impactful discoveries. Methods We leveraged several gene-disease association databases to calculate a Mutual Citation Score (MCS) for 10,853 pairs of genetically related diseases to measure the frequency of cross-citation between research fields. To assess the importance of cooperative research, we computed an Individual Disease Cooperation Score (ICS) and the average publication rate for each disease. Results For all disease pairs with one gene in common, we found that the degree of genetic overlap was a poor predictor of cooperation (r2=0.3198) and that the vast majority of disease pairs (89.56%) never cited previous discoveries of the same gene in a different disease, irrespective of the level of genetic similarity between the diseases. A fraction (0.25%) of the pairs demonstrated cross-citation in greater than 5% of their published genetic discoveries and 0.037% cross-referenced discoveries more than 10% of the time. We found strong positive correlations between ICS and publication rate (r2=0.7931), and an even stronger correlation between the publication rate and the number of cross-referenced diseases (r2=0.8585). These results suggested that cross-disease research may have the potential to yield novel discoveries at a faster pace than singular disease research. Conclusions Our findings suggest that the frequency of cross-disease study is low despite the high level of genetic similarity among many human diseases, and that collaborative methods may accelerate and increase the impact of new genetic discoveries. Until we have a better understanding of the taxonomy of human diseases, cross-disease research approaches should become the rule rather than the exception.
Maximal operators of Vilenkin-N?rlund means
L. E. Persson,G. Tephnadze,P. Wall
Mathematics , 2015,
Abstract: In this paper we prove and discuss some new $\left(H_{p},weak-L_{p}\right) $ type inequalities of maximal operators of Vilenkin-N\"orlund means with monotone coefficients. We also apply these results to prove a.e. convergence of such Vilenkin-N\"orlund means. It is also proved that these results are the best possible in a special sense. As applications, both some well-known and new results are pointed out.
Some new $\left(H_{p},L_{p}\right)$ type inequalities of maximal operators of Vilenkin-N?rlund means with non-decreasing coefficients
L. E. Persson,G. Tephnadze,P. Wall
Mathematics , 2015,
Abstract: In this paper we prove and discuss some new $\left(H_{p},L_{p}\right)$ type inequalities of maximal operators of Vilenkin-N\"orlund means with non-decreasing coefficients. We also apply these inequalities to prove strong convergence theorems of such Vilenkin-N\"orlund means. These inequalities are the best possible in a special sense. As applications, both some well-known and new results are pointed out.
A simple dependence between protein evolution rate and the number of protein-protein interactions
Hunter B Fraser, Dennis P Wall, Aaron E Hirsh
BMC Evolutionary Biology , 2003, DOI: 10.1186/1471-2148-3-11
Abstract: In contrast to a previous study that used an incomplete set of protein-protein interactions, we observed a highly significant correlation between number of interactions and evolutionary distance to either Candida albicans or Schizosaccharomyces pombe. This study differs from the previous one in that it includes all known protein interactions from S. cerevisiae, and a larger set of protein evolutionary rates. In both evolutionary comparisons, a simple monotonic relationship was found across the entire range of the number of protein-protein interactions. In agreement with our earlier findings, this relationship cannot be explained by the fact that proteins with many interactions tend to be important to yeast. The generality of these correlations in other kingdoms of life unfortunately cannot be addressed at this time, due to the incompleteness of protein-protein interaction data from organisms other than S. cerevisiae.Protein-protein interactions tend to slow the rate at which proteins evolve. This may be due to structural constraints that must be met to maintain interactions, but more work is needed to definitively establish the mechanism(s) behind the correlations we have observed.What factors determine the rates at which different proteins evolve is a fundamental question in molecular evolution. With the advent of functional genomics, this question can now be addressed on a genome-wide scale. Different determinants of evolutionary rate revealed by analysis of functional genomic data include protein dispensability [1], transcript level [2], and number of protein-protein interactors [3].Recently, Jordan et al. [4] suggested that the correlation between a protein's evolutionary rate and its number of protein interactions arises only because a few, highly interactive proteins evolve more slowly than all other proteins. In our original analysis, a distant genomic comparison of S. cerevisiae with C. elegans was used to find approximate evolutionary rates of putatively or
Structure and Magnetism of Fe/Si Multilayers Grown by Ion-Beam Sputtering
A. Chaiken,R. P. Michel,M. A. Wall
Physics , 1995, DOI: 10.1103/PhysRevB.53.5518
Abstract: Ion-beam sputtering has been used to prepare Fe/Si multilayers on a variety of substrates and over a wide range of temperatures. Small-angle x-ray diffraction and transmission electron microscopy experiments show that the layers are heavily intermixed although a composition gradient is maintained. When the spacer layer is an amorphous iron silicide, the magnetic properties of the multilayers are similar to those of bulk Fe. When the spacer layer is a crystalline silicide with the B2 or DO$_3$ structure, the multilayers show antiferromagnetic interlayer coupling like that observed in ferromagnet/paramagnet multilayers such as Fe/Cr and Co/Cu. Depending on the substrate type and the growth temperature, the multilayers grow in either the (011) or (001) texture. The occurrence of the antiferromagnetic interlayer coupling is dependent on the crystallinity of the iron and iron silicide layers, but does not seem to be strongly affected by the perfection of the layering or the orientation of the film. Since the B2- and DO$_3$-structure Fe$\rm _x$Si$\rm _{1-x}$ compounds are known to be metallic, antiferromagnetic interlayer coupling in Fe/Si multilayers probably originates from the same quantum-well and Fermi surface effects as in Fe/Cr and Co/Cu multilayers.
The CoNFIG Catalogue - II. Comparison of Space Densities in the FR Dichotomy
Melanie A. Gendre,P. N. Best,J. V. Wall
Physics , 2010, DOI: 10.1111/j.1365-2966.2010.16413.x
Abstract: This paper focuses on a comparison of the space densities of FRI and FRII sources at different epochs, with a particular focus on FRI sources. First, we present the concluding steps in constructing the Combined NVSS-FIRST Galaxy catalogue (CoNFIG), including new VLA observations, optical identifications and redshift estimates. The final catalogue consists of 859 sources over 4 samples (CoNFIG-1, 2, 3 and 4 with flux density limits of S_1.4GHz = 1.3, 0.8, 0.2 and 0.05 Jy respectively). It is 95.7% complete in radio morphology classification and 74.3% of the sources have redshift data. Combining CoNFIG with complementary samples, the distribution and evolution of FRI and FRII sources are investigated. We find that FRI sources undergo mild evolution and that, at the same radio luminosity, FRI and FRII sources show similar space density enhancements in various redshift ranges, possibly implying a common evolution.
Structural characterization of YBa(2)Cu(3)O(7)/Y(2)O(3) composite films
P. R. Broussard,M. A. Wall,J. Talvacchio
Physics , 1997, DOI: 10.1557/JMR.1998.0133
Abstract: Using 4-circle x-ray diffraction and transmission electron microscopy we have studied the microstructure and in-plane orientation of the phases present in thin film composite mixtures of YBa(2)Cu(3)O(7) and Y(2)O(3). We see a high degree of in-plane orientation and have verified a previous prediction for the in-plane order of Y(2)BaCuO(5) on (110) MgO. Transmission electron microscopy shows the composite films to be a mixture of two phases, with YBCO grain sizes of 1 micron. We have also compared our observations of the in-plane order to the predictions of a modified near coincidence site lattice model.
The Deep Diffuse Extragalactic Radio Sky at 1.75 GHz
T. Vernstrom,Ray P. Norris,Douglas Scott,J. V. Wall
Physics , 2014, DOI: 10.1093/mnras/stu2595
Abstract: We present a study of diffuse extragalactic radio emission at $1.75\,$GHz from part of the ELAIS-S1 field using the Australia Telescope Compact Array. The resulting mosaic is $2.46\,$deg$^2$, with a roughly constant noise region of $0.61\,$deg$^2$ used for analysis. The image has a beam size of $150 \times60\,$arcsec and instrumental $\langle\sigma_{\rm n}\rangle= (52\pm5)\, \mu$Jy beam$^{-1}$. Using point-source models from the ATLAS survey, we subtract the discrete emission in this field for $S \ge 150\, \mu$Jy beam$^{-1}$. Comparison of the source-subtracted probability distribution, or \pd, with the predicted distribution from unsubtracted discrete emission and noise, yields an excess of $(76 \pm 23) \, \mu$Jy beam$^{-1}$. Taking this as an upper limit on any extended emission we constrain several models of extended source counts, assuming $\Omega_{\rm source} \le 2\,$arcmin. The best-fitting models yield temperatures of the radio background from extended emission of $T_{\rm b}=(10\pm7) \,$mK, giving an upper limit on the total temperature at $1.75\,$GHz of $(73\pm10)\,$mK. Further modelling shows that our data are inconsistent with the reported excess temperature of ARCADE2 to a source-count limit of $1\, \mu$Jy. Our new data close a loop-hole in the previous constraints, because of the possibility of extended emission being resolved out at higher resolution. Additionally, we look at a model of cluster halo emission and two WIMP dark matter annihilation source-count models, and discuss general constraints on any predicted counts from such sources. Finally, we report the derived integral count at $1.4\,$GHz using the deepest discrete count plus our new extended-emission limits, providing numbers that can be used for planning future ultra-deep surveys.
Overcoming phase 1 delays: the critical component of obstetric fistula prevention programs in resource-poor countries
L Wall
BMC Pregnancy and Childbirth , 2012, DOI: 10.1186/1471-2393-12-68
Abstract: Obstetric fistulas can be prevented through contraception, avoiding obstructed labor, or improving outcomes for women who develop obstructed labor. Contraception is of little use to women who are already pregnant and there is no reliable screening test to predict obstruction in advance of labor. Improving the outcome of obstructed labor depends on prompt diagnosis and timely intervention (usually by cesarean section). Because obstetric fistulas are caused by tissue compression, the time interval from obstruction to delivery is critical. This time interval is often extended by delays in deciding to seek care, delays in arriving at a hospital, and delays in accessing treatment after arrival. Communities can reasonably demand that governments and healthcare institutions improve the second (transportation) and third (treatment) phases of delay. Initial delays in seeking hospital care are caused by failure to recognize that labor is prolonged, confusion concerning what should be done (often the result of competing therapeutic pathways), lack of women’s agency, unfamiliarity with and fear of hospitals and the treatments they offer (especially surgery), and economic constraints on access to care.Women in resource-poor countries will use institutional obstetric care when the services provided are valued more than the competing choices offered by a pluralistic medical system. The key to obstetric fistula prevention is competent obstetrical care delivered respectfully, promptly, and at affordable cost. The utilization of these services is driven largely by trust.Labor becomes obstructed when the progress of the fetus through the pelvis is arrested, in spite of ongoing, vigorous uterine contractions [1,2]. Untreated prolonged obstructed labor is one of the five most common causes of maternal mortality in poor countries (the others being hemorrhage, hypertensive disorders of pregnancy, sepsis, and complications of unsafe abortion) [2]. In addition to being a major cause of mate

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