The Song Of The Brook

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Disconnection in the Alexandroff duplicate

[EN] It was demonstrated in [2] that the Alexandroff duplicate of the Čech-Stone compactification of the naturals is not extremally disconnected. The question was raised as to whether the Alexandroff duplicate of a non-discrete extremally disconnected space can ever be extremally disconnected. We answer this question in the affirmative; an example of van Douwen is significant. In a slightly different direction we also characterize when the Alexandroff duplicate of a space is a P-space as well as when it is an almost P-space.Bhattacharjee, P.; Knox, ML.; Mcgovern, WW. (2021). Disconnection in the Alexandroff duplicate. Applied General Topology. 22(2):331-344. https://doi.org/10.4995/agt.2021.14602OJS331344222P. Alexandrov and P. Urysohn, Memoire sur les espaces topologiques compacts, Verh. Akad. Wetensch. Amsterdam, 14 (1929), 1-96.K. Almontashery and L. Kalantan, Results about the Alexandroff duplicate space, Appl. Gen. Topol. 17, no. 2 (2016), 117-122. https://doi.org/10.4995/agt.2016.4521A. V. Arkhangel'skii, Topological Function Spaces, Mathematics and Its Applications, 78, Springer, Netherlands, 1992. https://doi.org/10.1007/978-94-011-2598-7G. Bezhanishvili, N. Bezhanishvili, J. Lucero-Bryan and J. van Mill, S4.3 and hereditarily extremally disconnected spaces, Georgian Mathematical Journal 22, no. 4 (2015), 469-475. https://doi.org/10.1515/gmj-2015-0041A. Caserta and S. Watson, The Alexandroff duplicate and its subspaces, Appl. Gen. Topol. 8, no. 2 (2007), 187-205. https://doi.org/10.4995/agt.2007.1880R. Engelking, On functions defined on Cartesian products, Fund. Math. 59 (1966), 221-231. https://doi.org/10.4064/fm-59-2-221-231L. Gillman and M. Jerison, Rings of Continuous Functions, Graduate Texts in Mathametics, vol. 43, Springer Verlag, Berlin-Heidelberg-New York, 1976.E. van Douwen, Applications of maximal topologies, Topology Appl. 51 (1993), 125-139. https://doi.org/10.1016/0166-8641(93)90145-4J. van Mill, Weak P-points in Čech-Stone compactifications, Trans. Amer. Math. Soc. 273 (1982), 657-678. https://doi.org/10.2307/1999934J. L. Verner, Lonely points revisited, Comment. Math. Univ. Carolin. 54, no. 1 (2013), 105-110

A study of the effects caused by freezing automatic sprinkler heads

Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1914by Wm. H. Warren.B.S

Miniature, low-power X-ray tube using a microchannel electron generator electron source

Embodiments of the invention provide a novel, low-power X-ray tube and X-ray generating system. Embodiments of the invention use a multichannel electron generator as the electron source, thereby increasing reliability and decreasing power consumption of the X-ray tube. Unlike tubes using a conventional filament that must be heated by a current power source, embodiments of the invention require only a voltage power source, use very little current, and have no cooling requirements. The microchannel electron generator comprises one or more microchannel plates (MCPs), Each MCP comprises a honeycomb assembly of a plurality of annular components, which may be stacked to increase electron intensity. The multichannel electron generator used enables directional control of electron flow. In addition, the multichannel electron generator used is more robust than conventional filaments, making the resulting X-ray tube very shock and vibration resistant

The impact of vancomycin susceptibility on treatment outcomes among patients with methicillin resistant Staphylococcus aureus bacteremia

<p>Abstract</p> <p>Background</p> <p>Management of methicillin-resistant <it>Staphylococcus aureus </it>(MRSA) bacteremia remains a challenge. The emergence of MRSA strains with reduced vancomycin susceptibility complicates treatment.</p> <p>Methods</p> <p>A prospective cohort study (2005-2007) of patients with MRSA bacteremia treated with vancomycin was performed at an academic hospital. Vancomycin minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined for stored MRSA isolates. Cox regression analysis was performed to predict 28-day all-cause mortality.</p> <p>Results</p> <p>One hundred sixty-three patients with MRSA bacteremia were evaluated. One hundred twelve patients (68.7%) had bacteremia due to MRSA with a vancomycin MIC ≥ 2 <it>ug</it>/mL. Among strains with a vancomycin MIC ≥ 2 <it>ug</it>/mL, 10 isolates (8.9%) were vancomycin-intermediate <it>S. aureus </it>(VISA). Thirty-five patients (21.5%) died within 28 days after the diagnosis of MRSA bacteremia. Higher vancomycin MIC was not associated with mortality in this cohort [adjusted hazard ratio (aHR), 1.57; 95% confidence interval (CI), 0.73-3.37]. Vancomycin tolerance was observed in 4.3% (7/162) of isolates and was not associated with mortality (crude HR, 0.62; 95% CI, 0.08-4.50). Factors independently associated with mortality included higher age (aHR, 1.03; 95% CI 1.00-1.05), cirrhosis (aHR, 3.01; 95% CI, 1.24-7.30), and intensive care unit admission within 48 hours after the diagnosis of bacteremia (aHR, 5.99; 95% CI, 2.86-12.58).</p> <p>Conclusions</p> <p>Among patients with MRSA bacteremia treated with vancomycin, reduced vancomycin susceptibility and vancomycin tolerance were not associated with mortality after adjusting for patient factors. Patient factors including severity of illness and underlying co-morbidities were associated with the mortality.</p

The classical ring of quotients of Cc(X)C_c(X)

[EN] We construct the classical ring of quotients of the algebra of continuous real-valued functions with countable range. Our construction is a slight modification of the construction given in [M. Ghadermazi, O.A.S. Karamzadeh, and M. Namdari, On the functionally countable subalgebra of C(X), Rend. Sem. Mat. Univ. Padova, to appear]. Dowker's example shows that the two constructions can be different.Bhattacharjee, P.; Knox, ML.; Mcgovern, WW. (2014). The classical ring of quotients of $C_c(X)$. Applied General Topology. 15(2):147-154. doi:http://dx.doi.org/10.4995/agt.2014.3181.SWORD147154152Hager, A. W., Kimber, C. M., & McGovern, W. W. (2005). Unique a-closure for some ℓ-groups of rational valued functions. Czechoslovak Mathematical Journal, 55(2), 409-421. doi:10.1007/s10587-005-0031-zHenriksen, M., & Woods, R. G. (2004). Cozero complemented spaces; when the space of minimal prime ideals of a C(X) is compact. Topology and its Applications, 141(1-3), 147-170. doi:10.1016/j.topol.2003.12.004Knox, M. L., & McGovern, W. W. (2008). Rigid extensions of ℓ-groups of continuous functions. Czechoslovak Mathematical Journal, 58(4), 993-1014. doi:10.1007/s10587-008-0064-1R. Levy and M. D. Rice, Normal $P$-spaces and the $G_delta$-topology, Colloq. Math. 44, no. 2 (1981), 227-240.Levy, R., & Shapiro, J. (2005). Rings of quotients of rings of functions. Topology and its Applications, 146-147, 253-265. doi:10.1016/j.topol.2003.03.003A. Mysior, Two easy examples of zero-dimensional spaces, Proc. Amer. Math. Soc. 92, no. 4 (1984), 615-617.Porter, J. R., & Woods, R. G. (1988). Extensions and Absolutes of Hausdorff Spaces. doi:10.1007/978-1-4612-3712-9Rudin, W. (1957). Continuous functions on compact spaces without perfect subsets. Proceedings of the American Mathematical Society, 8(1), 39-39. doi:10.1090/s0002-9939-1957-0085475-

Laboratory study on the mobility of major species in fly ash–brine co-disposal systems: up-flow percolation test

Apart from the generation of fly ash, brine (hyper-saline wastewater) is also a waste material generated in South African power stations as a result of water re-use. These waste materials contain major species such as Al, Si, Na, K, Ca, Mg, Cl and SO4. The co-disposal of fly ash and brine has been practiced by some power stations in South Africa with the aim of utilizing the fly ash to capture the salts in brine. The effect of the chemical interaction of the species contained in both fly ash and brine, when co-disposed, on the mobility of species in the fly ash–brine systems is the focus of this study. The up-flow percolation test was employed to determine the mobility of some major species in the fly ash–brine systems. The results of the analysed eluates from the up-flow percolation tests revealed that some species such as Al, Ca and Na were leached from the fly ash into the brine solution while some species such as Mg, Cl and SO4 were removed to some extent from the brine solution during the interaction with fly ash. The pH of the up-flow percolation systems was observed to play a significant role on the mobility of major species from the fly ash–brine systems. The study showed that some major species such as Mg, Cl and SO4 could be removed from brine solution using fly ash when certain amount of brine percolates through the ash.Web of Scienc

The development and characterization of a 60K SNP chip for chicken

<p>Abstract</p> <p>Background</p> <p>In livestock species like the chicken, high throughput single nucleotide polymorphism (SNP) genotyping assays are increasingly being used for whole genome association studies and as a tool in breeding (referred to as genomic selection). To be of value in a wide variety of breeds and populations, the success rate of the SNP genotyping assay, the distribution of the SNP across the genome and the minor allele frequencies (MAF) of the SNPs used are extremely important.</p> <p>Results</p> <p>We describe the design of a moderate density (60k) Illumina SNP BeadChip in chicken consisting of SNPs known to be segregating at high to medium minor allele frequencies (MAF) in the two major types of commercial chicken (broilers and layers). This was achieved by the identification of 352,303 SNPs with moderate to high MAF in 2 broilers and 2 layer lines using Illumina sequencing on reduced representation libraries. To further increase the utility of the chip, we also identified SNPs on sequences currently not covered by the chicken genome assembly (Gallus_gallus-2.1). This was achieved by 454 sequencing of the chicken genome at a depth of 12x and the identification of SNPs on 454-derived contigs not covered by the current chicken genome assembly. In total we added 790 SNPs that mapped to 454-derived contigs as well as 421 SNPs with a position on Chr_random of the current assembly. The SNP chip contains 57,636 SNPs of which 54,293 could be genotyped and were shown to be segregating in chicken populations. Our SNP identification procedure appeared to be highly reliable and the overall validation rate of the SNPs on the chip was 94%. We were able to map 328 SNPs derived from the 454 sequence contigs on the chicken genome. The majority of these SNPs map to chromosomes that are already represented in genome build Gallus_gallus-2.1.0. Twenty-eight SNPs were used to construct two new linkage groups most likely representing two micro-chromosomes not covered by the current genome assembly.</p> <p>Conclusions</p> <p>The high success rate of the SNPs on the Illumina chicken 60K Beadchip emphasizes the power of Next generation sequence (NGS) technology for the SNP identification and selection step. The identification of SNPs from sequence contigs derived from NGS sequencing resulted in improved coverage of the chicken genome and the construction of two new linkage groups most likely representing two chicken micro-chromosomes.</p

Individual Differences in Sound-in-Noise Perception Are Related to the Strength of Short-Latency Neural Responses to Noise

Important sounds can be easily missed or misidentified in the presence of extraneous noise. We describe an auditory illusion in which a continuous ongoing tone becomes inaudible during a brief, non-masking noise burst more than one octave away, which is unexpected given the frequency resolution of human hearing. Participants strongly susceptible to this illusory discontinuity did not perceive illusory auditory continuity (in which a sound subjectively continues during a burst of masking noise) when the noises were short, yet did so at longer noise durations. Participants who were not prone to illusory discontinuity showed robust early electroencephalographic responses at 40–66 ms after noise burst onset, whereas those prone to the illusion lacked these early responses. These data suggest that short-latency neural responses to auditory scene components reflect subsequent individual differences in the parsing of auditory scenes