Chiral crossover in QCD at zero and non-zero chemical potentials

We present results for pseudo-critical temperatures of QCD chiral crossovers at zero and non-zero values of baryon ($B$), strangeness ($S$), electric charge ($Q$), and isospin ($I$) chemical potentials $\mu_{X=B,Q,S,I}$. The results were obtained using lattice QCD calculations carried out with two degenerate up and down dynamical quarks and a dynamical strange quark, with quark masses corresponding to physical values of pion and kaon masses in the continuum limit. By parameterizing pseudo-critical temperatures as $T_c(\mu_X) = T_c(0) \left[ 1 -\kappa_2^{X}(\mu_{X}/T_c(0))^2 -\kappa_4^{X}(\mu_{X}/T_c(0))^4 \right]$, we determined $\kappa_2^X$ and $\kappa_4^X$ from Taylor expansions of chiral observables in $\mu_X$. We obtained a precise result for $T_c(0)=(156.5\pm1.5)\;\mathrm{MeV}$. For analogous thermal conditions at the chemical freeze-out of relativistic heavy-ion collisions, i.e., $\mu_{S}(T,\mu_{B})$ and $\mu_{Q}(T,\mu_{B})$ fixed from strangeness-neutrality and isospin-imbalance, we found $\kappa_2^B=0.012(4)$ and $\kappa_4^B=0.000(4)$. For $\mu_{B}\lesssim300\;\mathrm{MeV}$, the chemical freeze-out takes place in the vicinity of the QCD phase boundary, which coincides with the lines of constant energy density of $0.42(6)\;\mathrm{GeV/fm}^3$ and constant entropy density of $3.7(5)\;\mathrm{fm}^{-3}$

Retrotransposon profiling of RNA polymerase III initiation sites

Although retroviruses are relatively promiscuous in choice of integration sites, retrotransposons can display marked integration specificity. In yeast and slime mold, some retrotransposons are associated with tRNA genes (tDNAs). In the Saccharomyces cerevisiae genome, the long terminal repeat retrotransposon Ty3 is found at RNA polymerase III (Pol III) transcription start sites of tDNAs. Ty1, 2, and 4 elements also cluster in the upstream regions of these genes. To determine the extent to which other Pol III-transcribed genes serve as genomic targets for Ty3, a set of 10,000 Ty3 genomic retrotranspositions were mapped using high-throughput DNA sequencing. Integrations occurred at all known tDNAs, two tDNA relics (iYGR033c and ZOD1), and six non-tDNA, Pol III-transcribed types of genes (RDN5, SNR6, SNR52, RPR1, RNA170, and SCR1). Previous work in vitro demonstrated that the Pol III transcription factor (TF) IIIB is important for Ty3 targeting. However, seven loci that bind the TFIIIB loader, TFIIIC, were not targeted, underscoring the unexplained absence of TFIIIB at those sites. Ty3 integrations also occurred in two open reading frames not previously associated with Pol III transcription, suggesting the existence of a small number of additional sites in the yeast genome that interact with Pol III transcription complexes

Compact realizations of optical super-resolution microscopy for the life sciences

Sandmeyer A. Compact realizations of optical super-resolution microscopy for the life sciences. Bielefeld: Universität Bielefeld; 2019

Membrane Stress Caused by Octanoic acid in Saccharomyces cerevisiae

In order to compete with petroleum-based fuel and chemicals, engineering a robust biocatalyst that can convert renewable feedstocks into biorenewable chemicals, such as carboxylic acids, is increasingly important. However, product toxicity is often problematic. In this study, the toxicity of the carboxylic acids hexanoic, octanoic, and decanoic acid on Saccharomyces cerevisiae was investigated, with a focus on octanoic acid. These compounds are completely inhibitory at concentrations of magnitude 1 mM, and the toxicity increases as chain length increases and as media pH decreases. Transciptome analysis, reconstruction of gene regulatory network, and network component analysis suggested decreased membrane integrity during challenge with octanoic acid. This was confirmed by quantification of dose-dependent and chain length-dependent induction of membrane leakage, though membrane fluidity was not affected. This induction of membrane leakage could be significantly decreased by a period of pre-adaptation, and this preadaptation was accompanied by increased oleic acid content in the membrane, significantly increased production of saturated lipids relative to unsaturated lipids, and a significant increase in the average lipid chain length in the membrane. However, during adaptation cell surface hydrophobicity was not altered. The supplementation of oleic acid to the medium not only elevated the tolerance of yeast cells to octanoic acid but also attenuated the membrane leakiness. However, while attempts to mimic the oleic acid supplementation effects through expression of the Trichoplusia ni acyl-CoA Δ9 desaturase OLE1(TniNPVE desaturase) were able to increase the oleic acid content, the magnitude of the increase was not sufficient to reproduce the supplementation effect and increase octanoic acid tolerance. Similarly, introduction of cyclopropanated fatty acids through expression of the Escherichia coli cfa gene was not helpful for tolerance. Thus, we have provided quantitative evidence that carboxylic acids damage the yeast membrane and that manipulation of the lipid content of the membrane can increase tolerance, and possibly production, of these valuable products

Educational Experiences Of Rural Minnesota High-Ability Mathematics Learners

Meeting the educational needs of rural Minnesota high school high-ability learners in mathematics can be challenging for educators. This qualitative study involved interviewing high school graduates who scored between 30 and 36 on the mathematics subtest of the ACT and high school mathematics teachers who observed high-ability mathematics students. The graduates were from four different one-section or two-section schools from three counties in rural Minnesota. The purpose of this study was to use phenomenological qualitative research methods to identify educational experiences of high-ability mathematics learners from rural one-section and two-section high schools. There were two research questions guiding this study. First, what were the classroom experiences of high-ability learners in mathematics attending one-section and two-section high schools in rural Minnesota? Second, what classroom experiences have mathematics teachers of high-ability learners in mathematics observed while teaching students attending one-section and two-section high schools in rural Minnesota? The results of the study showed the high-ability students participated in a variety of activities in high-school, had parental support, and liked being challenged academically in mathematics. The high-ability students found math easy, preferred to work independently on projects, did not see a need for technology in the mathematics classroom other than calculators, were highly motivated to learn and do well, and enjoyed being with their peers. Furthermore, the students did not feel they were behind academically in college, when compared to their peers, even though they did not have the opportunity to participate in any special programming for high-ability students while in elementary school or high school. The teachers\u27 observations supported the students\u27 experiences except the teachers said technology in the mathematics classroom was important and the students can be challenging in the classroom

Laboratory studies of the glass furnace refractory structure

The control of contact refractory life and therefore furnace life is dependent to a considerable degree on the structural commitment of the refractory as well as on its physical and chemical nature. The nature and rate of refractory degradation can be controlled to a degree by the design of the furnace structure and by the complimentary assemblage of the refractory components of a structure. This latter is particularly true in the bottom lay-up of the tank melter. Principles of refractory behavior under stress of environment are basic. They are, however, sometimes compromised in practice with negative effects on furnace life. It is the purpose of this paper to present laboratory demonstrations supporting the above thesis. Some of the specific subjects discussed include the dynamics of melter-bottom wear and approaches to the stabilization of this zonal problem. The use of mortars and sub-paving ramming mixture to control joint attack in the furnace bottom has merit. Consideration must be given to metal attack as well as to reaction between refractory and glass. Since thermal factors are of importance in control of corrosive and erosive attack, consideration must be given to thermal profiles through refractory structures

Skewness and kurtosis of net baryon-number distributions at small values of the baryon chemical potential

We present results for the ratios of mean (MB), variance (σ2B), skewness (SB) and kurtosis (κB) of net baryon-number fluctuations obtained in lattice QCD calculations with physical values of light and strange quark masses. Using next-to-leading order Taylor expansions in baryon chemical potential we find that qualitative features of these ratios closely resemble the corresponding experimentally measured cumulant ratios of net proton-number fluctuations for beam energies down to √sNN≥19.6  GeV. We show that the difference in cumulant ratios for the mean net baryon-number, MB/σ2B=χB1(T,μB)/χB2(T,μB), and the normalized skewness, SBσB=χB3(T,μB)/χB2(T,μB), naturally arises in QCD thermodynamics. Moreover, we establish a close relation between skewness and kurtosis ratios, SBσ3B/MB=χB3(T,μB)/χB1(T,μB) and κBσ2B=χB4(T,μB)/χB2(T,μB), valid at small values of the baryon chemical potential