Diffusion-controlled annihilation A+B→0A + B \to 0: The growth of an AA particle island from a localized AA-source in the BB particle sea

We present the growth dynamics of an island of particles $A$ injected from a localized $A$-source into the sea of particles $B$ and dying in the course of diffusion-controlled annihilation $A+B\to 0$. We show that in the 1d case the island unlimitedly grows at any source strength $\Lambda$, and the dynamics of its growth {\it does not depend} asymptotically on the diffusivity of $B$ particles. In the 3d case the island grows only at $\Lambda > \Lambda_{c}$, achieving asymptotically a stationary state ({\it static island}). In the marginal 2d case the island unlimitedly grows at any $\Lambda$ but at $\Lambda < \Lambda_{*}$ the time of its formation becomes exponentially large. For all the cases the numbers of surviving and dying $A$ particles are calculated, and the scaling of the reaction zone is derived.Comment: 5 REVTEX pages, no figure

Koncentracija laktoferina u mlijeku krava tijekom involucije mliječne žlijezde s različitim bakteriološkim nalazima.

Lactoferrin is an iron-binding glycoprotein of the transferrin family, present in high concentrations in secretions from the mammary glands during the involution period, and has antimicrobial ability. To determine lactoferrin concentrations in bovine milk with different bacteriological findings, 151 quarter milk samples were collected on a dairy farm of the Holstein-Friesian breed in Vojvodina, Republic of Serbia. Classical microbiological methods were used for bacteria isolation, and ELISA analysis was used for lactoferrin concentration quantification. The most common isolated bacteria in bovine milk samples were Corynebacterium spp. (32.45%) and coagulase-negative staphylococci (4.64%) with lactoferrin concentrations of 6.0497 ± 1.6774 mg/mL and 5.2961 ± 1.3633 mg/mL, respectively. The lowest mean value of lactoferrin concentration was observed in uninfected quarters and quarters infected with environmental pathogens, while the highest concentration of lactoferrin was in udder quarters infected with Streptococcus agalactiae. One in four milk samples where Staphylococcus aureus was isolated had much lower lactoferrin concentrations (1.1736 mg/mL) than the other three samples (6.2089 ± 0.5016 mg/mL), which requires further research.Laktoferin, glikoprotein koji veže željezo, pripadnik porodice bjelančevina transferin, prisutan je u visokoj koncentraciji u sekretu mliječne žlijezde tijekom involucije i posjeduje antimikrobnu sposobnost. Radi utvrđivanja koncentracije laktoferina u mlijeku krava s različitim bakteriološkim nalazima, prikupljen je 151 pojedinačni uzorak mlijeka na farmi holštajn-frizijske pasmine na području Autonomne pokrajine Vojvodine Republike Srbije. Za identifikaciju bakterija korištene su klasične mikrobiološke metode i ELISA za određivanje koncentracije laktoferina. Najčešće izdvojene bakterije u uzorcima mlijeka krava bile su Corynebacterium spp. (32,45%) s koncentracijom laktoferina 6,0497 ± 1,6774 mg/mL i koagulaza negativni stafilokoki (4,64%) s koncentracijom laktoferina 5,2961 ± 1,3633 mg/mL. Najniža srednja vrijednost koncentracije laktoferina zabilježena je u negativnim četvrtima vimena i četvrtima inficiranim bakterijama iz okoliša, dok je najviša koncentracija laktoferina bila u četvrtima vimena inficiranima vrstom Streptococcus agalactiae. Jedan od četiriju uzoraka mlijeka gdje je bio izdvojen Staphylococcus aureus imao je znatno nižu vrijednost laktoferina (1,1736 mg/mL) od ostala tri uzorka (6,2089 ± 0,5016 mg/mL), što zahtijeva daljnja istraživanja

Asymptotic expansion for reversible A + B <-> C reaction-diffusion process

We study long-time properties of reversible reaction-diffusion systems of type A + B C by means of perturbation expansion in powers of 1/t (inverse of time). For the case of equal diffusion coefficients we present exact formulas for the asymptotic forms of reactant concentrations and a complete, recursive expression for an arbitrary term of the expansions. Taking an appropriate limit we show that by studying reversible reactions one can obtain "singular" solutions typical of irreversible reactions.Comment: 6 pages, no figures, to appear in PR

Diffusion-controlled annihilation A+B→0A + B \to 0 with initially separated reactants: The death of an AA particle island in the BB particle sea

We consider the diffusion-controlled annihilation dynamics $A+B\to 0$ with equal species diffusivities in the system where an island of particles $A$ is surrounded by the uniform sea of particles $B$. We show that once the initial number of particles in the island is large enough, then at any system's dimensionality $d$ the death of the majority of particles occurs in the {\it universal scaling regime} within which $\approx 4/5$ of the particles die at the island expansion stage and the remaining $\approx 1/5$ at the stage of its subsequent contraction. In the quasistatic approximation the scaling of the reaction zone has been obtained for the cases of mean-field ($d \geq d_{c}$) and fluctuation ($d < d_{c}$) dynamics of the front.Comment: 4 RevTex pages, 1 PNG figure and 1 EPS figur

Sea polarisation and the Drell-Hearn-Gerasimov sum-rule(s)

The Drell-Hearn-Gerasimov sum-rule is really two sum-rules: one for each of the valence and the sea/glue contributions to the nucleon wavefunction. The convergence of these sum-rules follows from the Froissart bound for spin dependent processes in QCD and is necessary for the consistency of the constituent quark model of low energy QCD. Some challenges for future polarised photoproduction experiments, for example at ELFE, are discussed.Comment: 10 pages, LaTe

Prevalencija gena za rezistenciju na meticilin i Panton-Valentine leukocidin u izolatima bakterije Staphylococcus aureus podrijetlom od goveda i ljudi.

Using the California Mastitis Test (CMT), on 46 highly productive dairy farms in Serbia, cows with milk secretion disorder were identified. Milk samples were taken from cows with positive CMT and from cows with clinical mastitis. Standard microbiological analysis of milk samples and API Staph confirmed the presence of 75 isolates of Staphylococcus aureus. Those 75 isolates, as well as 11 isolates of Staphylococcus aureus originating from humans were analyzed for the presence of genes encoding Panton-Valentine leukocidin (PVL) and PBP2A protein, responsible for methicillin resistance. The presence of gene encoding PVL was determined by PCR in 5 out of 75 (6.67%) and in 7 out of 11 (63.63%) bovine and human isolates of Staphylococcus aureus, respectively. The presence of the mecA gene was determined by PCR in 1 of 75 (1.33%) and in 2 of 11 (18.18%) bovine and human isolates of Staphylococcus aureus, respectively. The presence of the mecC gene was not determined in analyzed isolates. Further research is needed to investigate the genetic relationship between bovine and human Staphylococcus aureus isolates, to determine the exact impact of bovine Staphylococcus aureus strains from the cow udders on animal and public health.Uporabom kalifornijskog testa za upalu vimena na 46 visoko produktivnih mliječnih farmi u Srbiji identificirane su krave s poremećajem sekrecije mlijeka. Uzeti su uzorci mlijeka krava pozitivnih kalifornijskim testom i krava s kliničkim mastitisom. Standardnom mikrobiološkom pretragom uzoraka mlijeka i identifikacijom kompletom API Staph potvrđena je prisutnost 75 izolata bakterije Staphylococcus aureus. Tih 75 izolata, kao i 11 izolata te bakterije podrijetlom iz ljudi bili su analizirani lančanom reakcijom polimerazom na prisutnost gena koji kodiraju za Panton-Valentine leukocidin (PVL) i PBP2A protein odgovoran za meticilinsku rezistenciju. Prisutnost gena koji kodira za PVL dokazana je u pet od 75 (6,67%) izolata podrijetlom iz goveda i u sedam od 11 (63,63%) izolata podrijetlom iz ljudi. Prisutnost mecA gena dokazana je u jednog od 75 (1,33%) izolata podrijetlom iz goveda i u dva od 11 (18,18%) podrijetlom iz ljudi. Prisutnost mecC gena nije utvrđena u analiziranim izolatima. Potrebna su daljnja istraživanja kako bi se istražio odnos između izolata Staphylococcus aureus-a podrijetlom iz ljudi i iz goveda i odredio točan utjecaj sojeva vrste Staphylococcus aureus iz vimena krava na zdravlje životinja i zdravlje ljudi

x-Dependent Polarized Parton Distributions

Using QCD motivated and phenomenological considerations, we construct x- dependent polarized parton distributions, which evolve under GLAP evolution, satisfy DIS data and are within positivity constraints. Each flavor is done separately and the overall set can be used to predict polarization asymmetries for various processes. We perform our NLO analysis strictly in x space, avoiding difficulties in moment inversion. Small-x results and other physical considerations are discussed.Comment: 30 pages, 11 Postscript figure

Space-and time-resolved diffusion-limited binary reaction kinetics in capillaries: experimental observation of segregation, anomalous exponents, and depletion zone

An experimental investigation of one-dimensional, diffusion-limited A+B→C chemical reactions is reported. The persistence of reactant segregation and the formation of a depletion zone is observed and expressed in terms of the universal time exponents: α (motion of the boundary zone), β (width of instantaneous product formation zone), γ (rate of instantaneous local formation of product), δ (rate of instantaneous global formation of product), etc. There is good agreement with the recently predicted and/or simulated values: α =1/2, β =1/6, γ =2/3, δ =1/2, in contrast to classical predictions ( α =0, β =1/2, γ =0, δ =−1/2). Furthermore, classically the segregation would not be preserved and there would be no formation of a depletion zone and no motion (just dissipation) of the reaction zone. We also discuss the relations to electrode oxidation-reduction reactions, i.e., A+C→C where C is a catalyst, electrode, or “trap.”Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45162/1/10955_2005_Article_BF01049588.pd