Correction of balloon X-ray astronomy data for the effects of atmospheric attenuation, K X-ray escape, and energy resolution

Correction of balloon X ray astronomy data for atmospheric attenuation, escape, and energy resolutio

Strategies for Increased Lactic Acid Production from Algal Cake Fermentations at Low pH by Lactobacillus casei

We explored using de-oiled algal biomass (algal cake) as a low-value substrate for production of lactic acid in fermentations with Lactobacillus casei, and strategies for increasing lactic acid production at low pH. L. casei 12A algal cake (AC) fermentations showed carbohydrate and amino acid availability limit growth and lactic acid production. These nutritional requirements were effectively addressed with enzymatic hydrolysis of the AC using α-amylase, cellulase, and pepsin. Producing 0.075 g lactic acid per g AC from AC digested with all three enzymes. We explored heterologous expression of the cellulase gene (celE) from Clostridium thermocellum and the α-amylase gene (amyA) from Streptococcus bovis in L. casei 12A. Functional activity of CelE was not detected, but low-level activity of AmyA was achieved, and increased \u3e 1.5-fold using a previously designed synthetic promoter. Nonetheless, the improvement was insufficient to significantly increase lactic acid production. Thus, substantial optimization of amyA and celE expression in L. casei 12A would be needed to achieve activities needed to increase lactic acid production from AC. We explored transient inactivation of MutS as a method for inducing hypermutability and increasing adaptability of L. casei 12A and ATCC 334 to lactic acid at low pH. The wild type cells and their ΔmutS derivatives were subject to a 100-day adaptive evolution experiment, followed by repair of the ΔmutS lesion in representative isolates. Growth studies at pH 4.0 revealed that all four adapted strains grew more rapidly, to higher cell densities, and produced significantly more lactic acid than untreated wild-type cells. The greatest increases were observed from the adapted ΔmutS derivatives. Further examination of the 12A adapted ΔmutS derivative identified morphological changes, and increased survival at pH 2.5. Genome sequence analysis confirmed transient MutS inactivation decreased DNA replication fidelity, and identified potential genotypic changes in 12A that might contribute to increased acid lactic acid resistance. Targeted inactivation of three genes identified in the adapted 12A ΔmutS derivative revealed that a NADH dehydrogenase (ndh), phosphate transport ATP-binding protein PstB (pstB), and two-component signal transduction system (TCS) quorum-sensing histidine kinase (hpk) contribute to increased acid resistance in 12A

Studies on heterotrophic nitrification in a lake. [Translation from: Z.allg.Mikrobiol. 12 567-574, 1973. ]

In a lake the nitrogen compounds are liable to regular cycling in which nitrate is reduced and ammonium oxidised. As a nitrate maximum is regularly established in the upper part of the hypolimnion of a stratified summer lake, the authors have dealt in particular with the oxidising side of the nitrogen cycle. Described here are partial results of the nitrification in Plusssee. The Plusssee was chosen, since it is almost entirely without inflows, and, lying in a wooded basin, is well protected from the wind, and therefore stably stratified. In order to determine the number of autotrophic nitrificants the distribution of the Nitrosomonas and Nitrobacter spores in the lake were analysed. From the estimates on the determination of spore numbers of the heterotrophic nitrificants, 14 species in the pure culture were isolated and examined from morphological, biochemical and taxonomic viewpoints

Enhanced structural correlations accelerate diffusion in charge-stabilized colloidal suspensions

Theoretical calculations for colloidal charge-stabilized and hard sphere suspensions show that hydrodynamic interactions yield a qualitatively different particle concentration dependence of the short-time self-diffusion coefficient. The effect, however, is numerically small and hardly accessible by conventional light scattering experiments. Applying multiple-scattering decorrelation equipment and a careful data analysis we show that the theoretical prediction for charged particles is in agreement with our experimental results from aqueous polystyrene latex suspensions.Comment: 1 ps-file (MS-Word), 14 page

Pathological regional blood flow in opiate-dependent patients during withdrawal: A HMPAO-SPECT study

The aims of the present study were to investigate regional cerebral blood flow (rCBF) in heroin-dependent patients during withdrawal and to assess the relation between these changes and duration of heroin consumption and withdrawal data. The rCBF was measured using brain SPECT with Tc-99m-HMPAO in 16 heroin-dependent patients during heroin withdrawal. Thirteen patients received levomethadone at the time of the SPECT scans. The images were analyzed both visually and quantitatively, a total of 21 hypoperfused brain regions were observed in 11 of the 16 patients. The temporal lobes were the most affected area, hypoperfusions of the right and left temporal lobe were observed in 5 and 5 patients, respectively. Three of the patients had a hypoperfusion of the right frontal lobe, 2 patients showed perfusion defects in the left frontal lobe, right parietal lobe and left parietal lobe. The results of the quantitative assessments of the rCBF were consistent with the results of the qualitative findings. The stepwise regression analysis showed a significant positive correlation (r = 0.54) between the dose of levomethadone at the time of the SPECT scan and the rCBF of the right parietal lobe. Other significant correlations between clinical data and rCBF were not found. The present results suggest brain perfusion abnormalities during heroin withdrawal in heroin-dependent patients, which are not due to the conditions of withdrawal

Long-term survival and interruption of HAART in HIV-related pulmonary hypertension

Reported here is a case of a patient with pulmonary arterial hypertension related to HIV (PAHRH) in which lipodystrophy necessitated interruption of highly active antiretroviral therapy (HAART) and long-term survival was the outcome. Although previous studies have suggested antiretroviral therapy may benefit patients with this rare complication of HIV infection, no worsening of PAHRH was observed when HAART was interrupted. Clinical and echocardiographic parameters remained stable during 7 months of follow up. In cases in which HAART is associated with relevant toxicity, interruption of HAART in patients with PAHRH can be considered, but should be used only if no alternatives are available. Close follow-up is warrante

Variations of the McEliece Cryptosystem

Two variations of the McEliece cryptosystem are presented. The first one is based on a relaxation of the column permutation in the classical McEliece scrambling process. This is done in such a way that the Hamming weight of the error, added in the encryption process, can be controlled so that efficient decryption remains possible. The second variation is based on the use of spatially coupled moderate-density parity-check codes as secret codes. These codes are known for their excellent error-correction performance and allow for a relatively low key size in the cryptosystem. For both variants the security with respect to known attacks is discussed

Infinite-dimensional diffusions as limits of random walks on partitions

The present paper originated from our previous study of the problem of harmonic analysis on the infinite symmetric group. This problem leads to a family {P_z} of probability measures, the z-measures, which depend on the complex parameter z. The z-measures live on the Thoma simplex, an infinite-dimensional compact space which is a kind of dual object to the infinite symmetric group. The aim of the paper is to introduce stochastic dynamics related to the z-measures. Namely, we construct a family of diffusion processes in the Toma simplex indexed by the same parameter z. Our diffusions are obtained from certain Markov chains on partitions of natural numbers n in a scaling limit as n goes to infinity. These Markov chains arise in a natural way, due to the approximation of the infinite symmetric group by the increasing chain of the finite symmetric groups. Each z-measure P_z serves as a unique invariant distribution for the corresponding diffusion process, and the process is ergodic with respect to P_z. Moreover, P_z is a symmetrizing measure, so that the process is reversible. We describe the spectrum of its generator and compute the associated (pre)Dirichlet form.Comment: AMSTex, 33 pages. Version 2: minor changes, typos corrected, to appear in Prob. Theor. Rel. Field

Phase Behaviour of Amphiphilic Monolayers: Theory and Simulation

Coarse grained models of monolayers of amphiphiles (Langmuir monolayers) have been studied theoretically and by computer simulations. We discuss some of the insights obtained with this approach, and present new simulation results which show that idealised models can successfully reproduce essential aspects of the generic phase behaviour of Langmuir monolayers.Comment: To appear in J. Phys.: Cond. Matte