9,861 research outputs found
A Roth theorem for amenable groups
No full textWe prove the following mean ergodic theorem: for any two commuting measure preserving actions {Tg} and {Sg} of a countable amenable group G on a probability space (X, A, μ), limn→∞ 1/|Φn| ∑g∈Φn φ(Tgx)ψ(SgTgx) exists in L1(X, A, μ) for any φ, ψ ∈ L2(X, A, μ), where {Φn} is any left Følner sequence for G. This generalizes Furstenberg\u27s ergodic Roth theorem, which corresponds to the case G = Z, Tg = Sg, as well as a more general result of Conze and Lesigne (which corresponds to the case G = Z with no restrictions on Tg and Sg). The limit is identified, and two combinatorial corollaries are obtained. The first of these states that in any subset E ⊂ G x G which is of positive upper density (with regard to any left Følner sequence in G x G), we may find triangular configurations of the form {(a, b), (ga, b), (ga, gb)}. This result has as corollaries Roth\u27s theorem on arithmetic progressions of length three and a theorem of Brown and Buhler guaranteeing solutions to the equation x + y = 2z in any sufficiently big subset of an abelian group of odd order. The second corollary states that if G x G x G is partitioned into finitely many cells, one of these cells contains configurations of the form {(a, b, c), (ga, b, c,), (ga, gb, c), (ga, gb, gc)}
The effect of gluconic acid on growth and intestinal microflora of weanling pigs
No full textThe effect of gluconic acid on growth and intestinal microflora of weanling pigs (Einfluss von Gluconsäure auf Wachstum und intestinale Mikroflora von Absetzferkeln). G. Biagi*, E. Vezzali, A. Piva and F.X. Roth – Bologna/Freising-Weihenstephan
The finding that antibiotics fed to farm animals as growth promoters can be responsible for the spreading of resistant bacteria and the consumer demands for a food chain free of drugs determine the need to study alternative strategies to control microbial activity in the gastrointestinal system of monogastric animals. Gluconic acid (GA) has been shown to reach the large intestine in rats where it can be fermented by the microflora (1). Aim of this study was the evaluation of the effect of feeding GA on piglet growth and intestinal microflora.
Methods: Immediately after weaning, 48 piglets were divided into 4 groups (12 animals per group, housed in individual cages) for a 6 week trial. Treatments were a commercial diet with a) no addition (control diet) or with b) 0.3%, c) 0.6%, and d) 1.2% of GA. Feed and water were provided ad libitum. Animals were weighed every week and feed consumption was recorded. At day 10 and 31, faecal samples were collected from 6 animals per group and cultured for viable bacteria (coliforms, clostridia and lactobacilli). At the end of the trial, 4 animals per group were killed. Samples of jejunum and caecum content were cultured for viable bacteria and their ammonia and volatile fatty acids (VFA) content as well as pH were determined.
Results: Feeding 0.3 and 0.6% of gluconic acid increased average daily gain (ADG) compared to control (P < 0,10), while gain to feed ratio (GF) was not influenced by treatments (Table 1). Faecal bacterial counts after 2 weeks did not show any differences. At week 5, coliforms were markedly reduced by the 0.3% GA treatment compared to control (P < 0.10) and all GA diets showed a tendential increase of the number of lactobacilli. In the caecum, clostridia were significantly reduced by GA at 0.6 and 1.2% (P < 0,10). As previously observed in the faeces, lactobacilli were tendentially increased in the caecum by GA. Ammonia concentration in the intestinal samples was not influenced by treatments. VFA in the intestine were increased by GA, but the differences observed did not reach the significance level due to the high variability. Interestingly, GA mainly increased acetic acid in the jejunum and butyric acid in the caecum.
Table 1. Live weight, average daily gain (ADG), daily feed intake and feed to gain ratio (FG) of piglets in the 6 weeks after weaning. Values are means of 12 animals ± SD.
Final live weight ADG Daily feed intake FG
(kg) (g/d) (g/d)
Control 25.08 ± 3,09 423 ± 67 704 ± 121 1.67 ± 0.06
Gluconic acid 0.3% 26.73 ± 2,73* 464 ± 55* 754 ± 108 1.62 ± 0.07
Gluconic acid 0.6% 26.85 ± 2,95* 466 ± 71* 749 ± 94 1.62 ± 0.08
Gluconic acid 1.2% 25.25 ± 2,22 428 ± 52 696 ± 68 1.63 ± 0.06
*Different from control by P < 0.10.
Conclusion: The present results show how feeding GA can improve the growth performances of piglets after weaning. Nevertheless, when used at a high concentration (1.2 %) the positive effect of GA was not observed. The bacterial counts and the VFA analyses show that GA may influence the composition and the activity of the intestinal microflora. Further studies will be needed to achieve a better understanding of the mode of action of GA in pigs.
1) ASANO, T, YUASA, K, YOSHIMURA, Y, TAKENAWA, S and FUKUBA, H (1997): J. Jpn. Soc. Nutr. Food Sci. 50, 287-294.
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*Department of Physiology and Animal Production, Faculty of Veterinary Medicine, University of Bologna, Via Tolara di Sopra 50, I-40064 Ozzano Emili
GA-Fuzzy PID control simulation waveform diagram.
No full textAs is well known, the metal annealing process has the characteristics of heat concentration and rapid heating. Traditional vacuum annealing furnaces use PID control method, which has problems such as high temperature fluctuation, large overshoot, and long response time during the heating and heating process. Based on this situation, some domestic scholars have adopted fuzzy PID control algorithm in the temperature control of vacuum annealing furnaces. Due to the fact that fuzzy rules are formulated through a large amount of on-site temperature data and experience summary, there is a certain degree of subjectivity, which cannot ensure that each rule is optimal. In response to this drawback, the author combined the technical parameters of vacuum annealing furnace equipment, The fuzzy PID temperature control of the vacuum annealing furnace is optimized using genetic algorithm. Through simulation and comparative analysis, it is concluded that the design of the fuzzy PID vacuum annealing furnace temperature control system based on GA optimization is superior to fuzzy PID and traditional PID control in terms of temperature accuracy, rise time, and overshoot control. Finally, it was verified through offline experiments that the fuzzy PID temperature control system based on GA optimization meets the annealing temperature requirements of metal workpieces and can be applied to the temperature control system of vacuum annealing furnaces.</div
Joseph Roth, Soma Morgenstern i glazba
No full textObwohl Roth behauptet hat, nichts von Musik zu verstehen, hat er sich in seinen journalistischen wie erzählerischen Texten intensiver mit Musik auseinandergesetzt, als man das zunächst vermuten möchte. Am Beginn und am Ende seiner bewussten musikalischen Erfahrung steht die jüdisch-ukrainische Folklore, die ihm sein Freund Soma Morgenstern ebenso vermittelt hat wie den Kontakt zur musikalischen Moderne.Despite his claim he knew nothing about music, Joseph Roth surprisingly wrote about it quite extensively in his journalistic and literary texts. The beginning and ending of his conscious musical experience is marked by
Jewish-Ukrainian folklore, introduced to him by his friend Soma Morgenstern, who also facilitated his encounter with modernism in music.Joseph Roth je tvrdio da se nimalo ne razumije u glazbu, no u svojim se publicističkim i pripovjednim tekstovima glazbom bavio intenzivnije no što bi se očekivalo. Na početku i na kraju Rothova glazbenog iskustva stoji židovsko-ukrajinski folklor. S njime ga je, ali i s glazbenom modernom, povezao njegov prijatelj Soma Morgenstern
Effects of feeding free or microencapsulated gluconic acid on growth performance of weanling pigs
No full textOrganic acids belong to the supplements that can be used as an alternative to antibiotics fed to farm animals as growth promoters. Gluconic acid (GA) has been shown to reach the large intestine in rats where it can be fermented by the microflora (1). In piglets, when GA was fed at 0.3 and 0.6%, average daily gain of the animals was improved (2). Aim of this study was the evaluation of the effect of feeding GA in its free form or microencapsulated on piglet growth and intestinal microflora.
Methods: Immediately after weaning, 48 piglets were divided into 3 groups (16 animals per group, housed in individual cages) for a 32 d trial. Treatments were a commercial diet with a) no addition (control diet) or with b) 0.3% of microencapsulated GA (MGA), and c) 0.3% of free GA (FGA). Feed and water were provided ad libitum. Animals were weighed every week and feed consumption was recorded. At the end of the trial, 8 animals per group were killed. Samples of jejunum and caecum content were cultured for viable bacteria (coliforms, clostridia, enterococci, and lactobacilli) and the content and the mucosa from the middle section of the jejunum and from ileum and cecum were sampled for pH, ammonia and SCFA determination, and for intestinal mucosa morphology analysis.
Results: Feeding GA did not influence live weight, average daily gain (ADG), and daily feed intake of piglets. Feed to gain ratio (FG) was improved by GA between Day 14 and 21 (1.68, 1.44, and 1.34 for control, MGA, and FGA, respectively; P < 0.05) but differences were not significant in the period 0-32 d (Table 1). Intestinal counts of viable bacteria were not significantly influenced by treatment. Nevertheless, caecal clostridia showed a tendency towards a reduction when GA was fed (6.9, 6.4, and 6.2 log10 CFU/g for control, MGA, and FGA, respectively). Ammonia concentration in the caecum was higher when MGA was fed (P < 0.01). Compared with control, feeding MGA reduced the concentration of iso-butyric acid in jejunum and ileum (P < 0.10) but no other differences in SCFA intestinal concentrations were observed. Animals receiving the FGA diet had longer ileal villi (+ 18%; P < 0.10) and shorter caecal crypts ( 17%; P < 0.05) than control animals.
Conclusion: Despite the fact that during a previous study GA had improved piglets growth performances (2), both the free and the microencapsulated form of GA failed to enhance animal growth. Further studies will be needed to achieve a deeper understanding of the effect that GA has on growth and intestinal ecology and morphology of piglets.
1) ASANO, T, YUASA, K, YOSHIMURA, Y, TAKENAWA, S and FUKUBA, H (1997): J. Jpn. Soc. Nutr. Food Sci. 50, 287-294.
2) BIAGI, G., PIVA, A., MOSCHINI, M., VEZZALI, E., and ROTH, F. X. (2005): J. Anim. Sci. Accepted for publication
Revisiting the Nd-142 deficits in the 1.48 Ga Khariar alkaline rocks, India
No full textThe 146Sm–142Nd system plays a central role in tracing the silicate differentiation of the Earth prior to 4.1 Ga. After this time, given its initial abundance, the 146Sm can be considered to be extinct. Upadhyay et al. (2009) reported unexpected negative 142Nd anomalies in 1.48 Ga rocks of the Khariar nepheline syenite complex (India) and inferred that an early enriched, low-Sm/Nd reservoir must have contributed to the mantle source rocks of the Khariar complex. As 146Sm had been effectively extinct for about 2.6 billion years before the crystallisation of the Khariar samples, this Nd signature should have remained isolated from the convective mantle for at least that long. It was thus suggested that the source rock of Khariar samples had been sequestered in the lithospheric root of the Indian craton. Using a different chemical separation method, and a different Thermal Ionization Mass Spectrometry (TIMS) analysis protocol, the present study attempted to replicate these negative 142Nd anomalies, but none were found. To determine which data set is correct, we investigated three possible sources of bias between them: imperfect cancellation of Faraday collector efficiencies during multidynamic TIMS analysis, rapid sample fractionation between the sequential measurement of 146Nd/144Nd and 142Nd/144Nd, and non-exponential law behaviour resulting from so-called “domain mixing.” Incomplete cancellation of collector efficiencies was found unlikely to cause resolvable biases at the estimated level of variation among collector efficiencies. Even in the case of highly variable efficiency and resolvable biases, there is no reason to suspect that they would reproducibly affect only four rocks out of 10 analysed by Upadhyay et al. (2009). Although domain mixing may explain apparent “reverse” fractionation trends observed in some TIMS analyses, it cannot be the cause of the apparent negative anomalies in the study of Upadhyay et al. (2009). It was determined that rapid mass fractionation during the course of a multidynamic TIMS analysis can bias all measured Nd ratios. After applying an approximate correction for this effect, only one rock from Upadhyay et al. (2009) retained an apparent negative 142Nd anomaly. This, in conjunction with our new, anomaly-free data set measured at fractionation rates too low to cause bias, leads to the conclusion that the anomalies reported by Upadhyay et al. (2009) are a subtle and reproducible analytical artefact. The absence of negative 142Nd anomalies in these rocks relaxes the need for a mechanism (other than crust formation) that can isolate a Nd reservoir from the convective mantle for billions of years
Increasing science, technology, engineering, and mathematics skills using Project Lead the Way
No full textIncludes bibliographical references
Thermally Induced In/ga Interdiffusion In Inxga1-xas/gaas Strained Single Quantum Well Grown By Lpmovpe
No full textA strained single quantum well of GaAs/InxGa1-xGa/GaAs (x=0.23) has been grown by low pressure MOVPE on a (100) GaAs substrate at 625° C. Samples were annealed under AsH3/H2 at different temperatures in the range 750 to 900° C. Since the quantum well thickness (∼80 Å) is below the critical value for this lattice mismatched system, we assume that the InGaAs layer is commensurate with the GaAs substrate. We analyse the low temperature (2 K) photoluminescence of the electron to heavy hole transition in the quantum well of these samples to study the In/Ga interdiffusion at the InGaAs/GaAs interfaces. The position in energy of the photoluminescence peaks shift to higher energies when annealing. The shifts are quantitatively interpreted in terms of changes in the quantum well profile due to the In and Ga interdiffusion. We determined the interdiffusion coefficient at 850° C to be 3×10-17 cm2/s, with an activation energy 2.07 eV. The values obtained for the In/Ga interdiffusion coefficient are larger than those published for the Al and Ga interdiffusion in AlGaAs/GaAs heterojunctions. © 1988.931-4336341Sullivan, Asbeck, Chang, Miller, Wang, (1986) Electron. Letters, 22, p. 419Adams, Band-structure engineering for low-threshold high-efficiency semiconductor lasers (1986) Electronics Letters, 22, p. 250Roth, Sacilotti, Masut, D'Arcy, Watt, Sproule, Mitchell, (1986) Appl. Phys. Letters, 48, p. 1452Characterization of GaxIn1−xAs/GaAs heterostructures grown by low pressure MOVPE (1986) Journal of Crystal Growth, 77, p. 571Roth, Sacilotti, Masut, Machado, D'Arcy, (1986) J. Appl. Phys., 60, p. 2003Roth, Masut, Sacilotti, Sproule, Mitchell, Le Page, (1987) Can. J. Phys., 65, p. 909Chang, Koma, (1976) Appl. Phys. Letters, 29, p. 138Meenan, Brown, Gavrilovic, Holonyak, Jr., Burnham, Paoli, Streifer, Thermal-anneal wavelength modification of multiple-well p-n AlxGa1−x As-GaAs quantum-well lasers (1984) Journal of Applied Physics, 55, p. 2672Schlesinger, Kuech, (1986) Appl. Phys. Letters, 49, p. 519Lee, Schlesinger, Kuech, Interdiffusion of Al and Ga in (Al,Ga)As/GaAs superlattices (1987) Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 5 B, p. 1187Fritz, Picraux, Dawson, Drummond, Laidig, Anderson, (1985) Appl. Phys. Letters, 46, p. 967Orders, Usher, (1987) Appl. Phys. Letters, 50, p. 980Anderson, Chen, Kulakovskii, Uddin, Valim, Variation of the critical layer thickness with In content in strained InxGa1−xAs-GaAs quantum wells grown by molecular beam epitaxy (1987) Applied Physics Letters, 51, p. 752Landolt-Börnstein, (1982) Numerical Data and Functional Relationships in Science and Technology, New Series, 17, p. 218. , O. Madelung, Springer, BerlinLandolt-Börnstein, (1982) Numerical Data and Functional Relationships in Science and Technology, New Series, 17, p. 297. , O. Madelung, BerlinChandrasekhar, Pollak, (1977) Phys. Rev., 15 B, p. 2127F. Iikawa, F. Cerdeira, C. Vazquez-Lopes, P. Motisuke, M.A. Sacilotti, A.P. Roth and R.A. Masut, to be publishedA.P. Roth, R.A. Masut, M.A. Sacilotti and B. Watt, unpublished, 1986;Goetz, Bimberg, Jürgensen, Selders, Solomonov, Glinskii, Razeghi, (1983) J. Appl. Phys., 54, p. 4543Bastard, Brum, (1986) IEEE J. Quantum Electron. QE-22, p. 1525Bastard, (1981) Phys. Rev., 24 B, p. 5693Bastard, (1982) Phys. Rev., 25 B, p. 7584Marzin, Charasse, Sermage, (1985) Phys. Rev., 31 B, p. 8298Ji, Huang, Reddy, Henderson, Houdre, Morkoç, (1987) J. Appl. Phys., 62, p. 3366Menendez, Pinczuk, Werder, Sputz, Miller, Sivco, Cho, Large valence-band offset in strained-layer In_{x}Ga_{1-x}As-GaAs quantum wells (1987) Physical Review B, 36 B, p. 8165Greene, Bajaj, Phelps, (1984) Phys. Rev., 29 B, p. 1807Crank, (1975) The Mathematics of Diffusion, p. 1. , 2nd ed., Clarendon, OxfordCrank, (1975) The Mathematics of Diffusion, p. 19. , 2nd ed., OxfordKendall, Semiconductors and Semimetals (1968) Physics of III–V Compounds, 4, p. 163. , R.K. Willardson, A.C. Beer, Academic Press, New YorkSeo, Bhattacharya, Kothiyal, Hong, (1986) Appl. Phys. Letters, 49, p. 96
High-loading Ga-exchanged MFI zeolites as selective and coke-resistant catalysts for nonoxidative ethane dehydrogenation
No full textIn this paper, we investigated the effects of the Ga loading amount and H-2 treatment temperature for the reductive solid-state ion-exchange reaction on the generated Ga species in Ga-exchanged MFI zeolites (Ga-MFIs) as well as their catalysis for ethane dehydrogenation (EDH). For the formation of isolated Ga hydrides in the zeolites, [GaH](2+) ions were preferentially formed in the low-loading Ga-MFI (Ga/Al = 0.3) treated with H-2 at 550 degrees C, corresponding to the conventional preparation conditions, (Ga-MFI-0.3(550)), while the high Ga loading (Ga/Al = 1.0) and high-temperature H-2 treatment (800 degrees C) (Ga-MFI-1.0(800)) induced the formation of [GaH2](+) ions as the major Ga hydrides, as revealed by in situ Fourier transform infrared spectroscopy including the isotope experiment using D-2. In the context of other Ga species, such as Ga+ cations and partially reduced Ga oxides (GaOX), Ga+ cations and GaOX coexist in Ga-MFI-0.3(550), as indicated by pyridine adsorption experiments. On the other hand, GaOX was hardly observed and a larger amount of Ga+ cations was formed in Ga-MFI-1.0(800). The remaining Bronsted acid sites (BASs) were also characterized by the NH3 adsorption experiment. In the EDH reaction, Ga-MFI-1.0(800) exhibited high selectivity owing to low coke formation, resulting in the highest durability among the series of Ga-MFIs tested. Under the optimized conditions, Ga-MFI-1.0(800) exhibited the highest C2H4 formation rate among previously reported Pt-free catalysts. Based on the combined results of characterization, catalyst tests, and kinetic studies, the high selectivity and durability of Ga-MFI-1.0(800) can be ascribed to the low amount of the remaining BASs by isolated Ga species ([GaH](2+), [GaH2](+) ions and Ga+ cations) as well as the major formation of [GaH2](+) ions among isolated Ga hydrides
Element Distribution in Porous Ga Oxide Obtained by Anodizing Ga in Phosphoric Acid
No full textA STEM/EDS study of a porous Ga oxide film formed by an anodization process was conducted in this study to examine the crystalline structure of the film and the elemental distribution in the oxide film before and after heat treatment. The as-formed anodic film with a morphology resembling the well-known porous anodic Al oxide film was amorphous, crystallizing after heat treatment at 600 degrees C without changing the morphology and elemental distribution. The EDS elemental maps disclosed the duplex nature of the pore wall oxide; the phosphate anion was contaminated in the outer oxide layer next to the pores, and the inner layer consisted of relatively pure Ga oxide, practically free from phosphate. The similarity of morphology and elemental distributions between the porous anodic Al and Ga oxides suggests that the growth of both anodic oxide films proceeds under the same mechanism. In addition, crystallized porous Ga oxides are expected to be applied to fabricate various functional devices requiring geometrically controlled semiconductor nanohole arrays, such as devices for hydrogen formation. (c) 2023 The Electrochemical Society ("ECS"). Published on behalf of ECS by IOP Publishing Limited
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